Electrolytic cell stack with low leakage current

Abstract

Disclosed is an electrolytic cell stack comprising: two substrates between which an element stack including an electrolytic cell is sandwiched; and at least one intermediate plate (30), which is clamped in the element stack. The intermediate plate (30) has a thickness within which at least one electrolyte supply line, a first line for discharging a first electrolytic product and a second line (33) for discharging a second electrolytic product are arranged, the at least one electrolyte supply conduit, the first conduit, and the second conduit are integrated with the supply network, the first discharge network, and the second discharge network, respectively. The length of each of said conduits (33) in the intermediate plate (30) has a greater thickness than the intermediate plate (30) and comprises a curved section (34) connecting the inlet and outlet orifices to each other.

Description

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

[0002] The overall structure of an electrolytic cell stack typically consists of electrolytic cell blocks and gaskets, with the electrolytic cells electrically connected in series and fluidly connected in parallel.

[0003] The purpose of each electrolytic cell is to facilitate the electrolysis of an electrolyte solution (alkaline water, pure water, unpurified water, salt, chloride aqueous solution, bromide aqueous solution, hydrochloric acid aqueous solution, etc.). For example, the function of an electrolytic cell stack is to promote the reaction of water dissociation to produce gaseous dihydrogen (H2) and gaseous hydrogen oxide (O2) after direct current is injected into an alkaline solution (usually potassium hydroxide (KOH) or sodium hydroxide (NaOH)).

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

[0005] The flow field material has two functions: i) to provide a metal path with low resistivity between each bipolar plate and the associated electrode, and ii) to allow proper flow of the electrolyte solution to cool the electrolytic cell stack and deliver the generated gas.

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

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

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

[0009] In addition to bipolar plates, other metal products numbered include distribution plates (which enable the supply and distribution of power to the electrolytic cells) and substrates (used to define the groups of electrolytic cells and clamp the electrolytic cells together and seal them).

[0010] Specifically, the electrolytic cell stack ends with two substrates located just before the first electrolytic cell in the stack and just after the last electrolytic cell in the stack. That is, one substrate is located upstream of the electrolytic cell block, while the other substrate is placed downstream of the electrolytic cell block to physically define the two ends of the electrolytic cell block.

[0011] To ensure ion conduction within the electrolytic cell, the electrolyte solution possesses high ionic conductivity. However, a risk exists that, due to this high ionic conductivity, leakage current can propagate through the electrolyte into the network used for supplying and discharging the two-phase mixture (one side being the electrolyte and hydrogen peroxide, and the other side being dihydrogen peroxide). These leakage currents reduce the overall efficiency of the electrolysis process.

[0012] These leakage currents can be compensated by reducing the cross-sectional area of ​​the conduit or by using conduits made of electrically insulating materials in the network used for supplying electrolytes and discharging the two-phase mixture.

[0013] The first solution results in head loss, which can lead to poor electrolyte distribution between cells and difficulty in venting gases produced during electrolysis. The second solution typically uses polymer materials, whose properties impose limitations on the pressure and temperature of the fluid flowing through the conduit.

[0014] Therefore, neither of these two solutions is optimal. Purpose of the invention

[0015] The purpose of this invention is to provide an electrolytic cell stack with improved efficiency. Summary of the Invention

[0016] To this end, the present invention provides an electrolytic cell stack comprising: two substrates sandwiching a component stack containing an electrolytic cell; and at least one intermediate plate sandwiched within the component stack. The intermediate plate has a thickness in which at least one electrolyte supply conduit, a first conduit for discharging a first electrolytic product, and a second conduit for discharging a second electrolytic product are formed, the at least one electrolyte supply conduit, the first conduit, and the second conduit being integrated with a supply network, a first discharge network, and a second discharge network, respectively. Each of these conduits formed in the intermediate plate has a length greater than the thickness of the intermediate plate and has at least one segment bent to form a U-shape having two branches extending side-by-side in the thickness direction of the intermediate plate.

[0017] Therefore, the conduits formed in the intermediate plate increase the resistance of the supply and discharge networks by increasing the length of the conduits without causing an equivalent increase in the axial dimension of the electrolyzer stack or affecting the flow rate of the fluid flowing in the networks at a given pumping capacity. Thus, this solution achieves a trade-off between the increased network resistance and the increased axial dimension of the electrolyzer stack, thereby impacting the overall efficiency of the electrolyzer stack.

[0018] The electrolytic cell stack according to the present invention may include one or more of the following optional features as needed:

[0019] - At least two intermediate plates are placed on both sides of multiple electrolytic cells;

[0020] - The plurality of electrolytic cells includes between ten and four hundred, preferably between twenty and fifty;

[0021] - The intermediate plate is one of the bipolar plates in these electrolytic cells;

[0022] - The intermediate plate is a current distribution plate that extends between the end plate and the adjacent electrolytic cell;

[0023] - The components are stacked vertically or horizontally.

[0024] Other features and advantages of the invention will become apparent when reading the following description of specific, non-limiting embodiments thereof. Attached Figure Description

[0025] Please refer to the attached diagram, in which:

[0026] Figure 1 This is an exploded view of an electrolytic cell in an electrolytic cell stack according to a specific embodiment of the present invention.

[0027] Figure 2 yes Figure 1 The presented three-dimensional diagram of the bipolar plates of the electrolytic cell.

[0028] Figure 3a yes Figure 2 A cross-sectional view of a portion of the bipolar plate shown.

[0029] Figure 3b yes Figure 2 The diagram shows a cross-sectional view of a portion of the bipolar plate, where the membrane of the electrolytic cell is also present.

[0030] Figure 3c yes Figure 1 The presented cross-sectional view of a portion of the electrolytic cell.

[0031] [ Figure 4 ] Figure 4 This includes, for example Figure 1The view shown is of the electrolytic cell stack.

[0032] Figure 5 This is a front view of the intermediate plate according to the present invention.

[0033] Figure 6 It is along Figure 5 A cross-sectional view of line VI-VI of the middle plate. Detailed Implementation

[0034] Referring to the accompanying drawings, the present invention relates to an electrolytic cell stack comprising a stack of elements extending longitudinally along a general direction A. The various elements are primarily formed from an electrolytic cell 10, which will be described below.

[0035] The electrolytic cell stack 1 includes a block 2 comprising electrolytic cells 10, each block comprising at least two electrolytic cells 10, which are continuously mounted to each other along the general direction A. Within the block 2, the electrolytic cells 10 are fluidly connected in parallel and electrically connected in series.

[0036] Two end plates or substrates 3 and 4 are placed at both ends (along the general direction A) of block 2 of electrolytic cell stack 1.

[0037] These substrates 3 and 4 form supports, and the electrolytic cell 10 is compressed between these supports, thereby sealing the electrolytic cell stack 1 and forming high-quality electrical contacts inside the electrolytic cell 10.

[0038] Furthermore, substrates 3 and 4 enable them to withstand forces generated by pressure inside block 2 as well as forces outside block 2, which are necessary to ensure the compression of block 2.

[0039] Substrates 3 and 4 can act as electrical conductors and current distributors.

[0040] Preferably, the electrolytic cell stack 1 includes a first distribution plate 5 associated with the first substrate 3 and a second distribution plate 6 associated with the second substrate 4. Thus, the distribution plates 5 and 6 will act as electrical conductors and current distributors.

[0041] 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 the block 2.

[0042] The concepts of "upstream" and "downstream" should be understood based on the normal direction of current flow through block 2.

[0043] The first distribution plate 5 of the two distribution plates is connected to the positive terminal of the electrolytic cell stack 1. A portion of the inner main surface of the first substrate 3 (facing the block 2, particularly the main surface facing the distribution plate 5) is covered with an electrical insulating material patch. This portion is, for example, arranged at the center of the inner main surface.

[0044] The second distribution plate 6 of the two distribution plates is connected to the negative terminal of the electrolytic cell stack 1. The second substrate 4 will be at the same potential and also serves as a passage for supplying the electrolyte solution and releasing the same solution loaded with the gas formed during electrolysis in block 2.

[0045] Therefore, holes are formed in the second substrate 4. These holes typically have different cross-sections between the two main surfaces of the second substrate 4. For example, the outer main surface (the main surface facing outwards from block 2) includes at least one or two holes (e.g., cylindrical) for supplying the electrolyte solution and two holes for discharging the treated electrolyte solution and electrolytic reaction products. For the same purpose, at least three or four holes, for example, holes with an elongated oval shape, are drilled on the inner main surface of the second substrate 4 (opposite to the outer main surface) to improve fluid distribution or collection. For example, the holes on the outer main surface are equipped with flanges suitable for attaching inlet and outlet pipes for the electrolyte solution.

[0046] In addition, the electrolytic cell stack 1 is supplied with direct current.

[0047] For example, the first distribution plate 5 is at a potential of several hundred volts, while the second distribution plate 6 is at a potential of 0 volts (the electrolytic cell stack 1 typically comprises between 10 and 400, preferably between 100 and 350, electrolytic cells 10, which have an electrolytic cell voltage of approximately 2 volts at the beginning of their rated life and preferably less than 1.85 volts). The supply and discharge of the electrolyte solution are carried out through the second distribution plate 6 and the second substrate 4. The second distribution plate 6 has a potential of 0 volts, which prevents any current leakage (the potential of the second distribution plate 6 is ground potential).

[0048] Inside the electrolytic cell stack 1, current flows through the electrolyte solution through membrane 11, which will be described below. Within block 2 are gaskets (described below): these gaskets are chosen to be made of a material with a resistance much higher than that of the electrolyte solution.

[0049] The electrolytic cell stack 1 includes end pads (not visible in the figure) disposed between the first distribution plate 5 and the first substrate 3. The first substrate 3 is grounded such that the potential difference at the end pads reaches the same value as the voltage applied between the positive and negative terminals of the electrolytic cell stack 1, for example, about 700 volts.

[0050] For this reason, the first substrate 3 is electrically isolated from the block 2.

[0051] For example, the electrolytic cell stack 1 includes a layer (not visible in the figure) made of an electrically insulating material, which is disposed between the first substrate 3 and the first distribution plate 5.

[0052] This layer is, for example, an additional disk or a deposit formed on the first substrate 3 and / or the first distribution plate 5.

[0053] The electrolytic cell stack 1 includes means for fixing the individual electrolytic cells 10 to each other by means of combined clamping.

[0054] For example, the fixing device includes a plurality of tie rods 7. Each tie rod 7 extends in a straight line in the stacking direction of the electrolytic cell stack 1. Therefore, each tie rod 7 extends longitudinally in the electrolytic cell stack 1 parallel to the overall direction A. Each tie rod 7 is configured as a rod.

[0055] Therefore, the pull rods 7 all extend parallel to each other. The pull rods 7 are located on the outer edge of each electrolytic cell 10. Preferably, the pull rods 7 are distributed around the block 2, and more preferably, they are distributed at regular intervals.

[0056] The pull rod 7 extends through the substrates 3 and 4 of the electrolytic cell stack 1, through specific holes in the substrates 3 and 4, and thus each has two ends located outside the block 2.

[0057] Preferably, the pull rod 7 is partially covered by a sleeve made of an electrically insulating material. This allows short circuits to be avoided between the electrolytic cells 10 in the event of contact or splashing. For example, the sleeve extends over the entire section between the two substrates 3 and 4 in the arrangement of the pull rod 7.

[0058] Preferably, the end of the pull rod 7 is threaded.

[0059] For example, the thread at the end is a rolled thread. Rolled threads will have the advantage of making the machining of the tie rod 7 easier, especially if the tie rod 7 has a large length, such as several meters.

[0060] The fixing device also includes a nut 8 that is screwed onto the end of the pull rod 7.

[0061] Nut 8 allows the two substrates 3 and 4 to be tightened together, and thus the individual electrolytic cells 10 to be tightened together, which ensures a good seal of the electrolytic cell stack 1 of the electrolytic cells 10.

[0062] Preferably, the fixing device further includes means for pre-tightening the two substrates 3 and 4 to each other and thus to pre-tightening the respective electrolytic cells 10 to each other. The pre-tightening means also makes it possible to absorb deformation and / or thickness changes of the elements constituting the electrolytic cell stack 1 caused by thermal expansion or changes in mechanical stresses (e.g., pressure inside the electrolytic cell stack 1) outside and inside the electrolytic cell stack 1.

[0063] The preload device is received on the end of the pull rod 7 such that, for a given end, the preload device is arranged between the nearest base plate (3 or 4) and the nut 8 arranged on the same end.

[0064] For example, the fixing device includes a spring washer 9, such as a Bellwell washer. The spring washer 9 is received on the end of the pull rod 7.

[0065] More precisely, here, the spring washer 9 is placed on the outer portion of each pull rod 7 as the pull rod 7 passes through the nearest substrate (3 or 4).

[0066] The fixture described in this way allows the electrolytic cell stack 1 to specifically cope with the thermal expansion and / or changes of mechanical stresses (e.g., pressure inside the electrolytic cell stack 1) both outside and inside the electrolytic cell stack 1.

[0067] In this example, all the electrolytic cells 10 in the electrolytic cell stack 1 are identical to each other, such that the following description of the electrolytic cells 10 also applies to the description of the other electrolytic cells 10.

[0068] This electrolytic cell 10 includes a central membrane 11 framed by two electrodes 12a and 12b (anode and cathode, respectively), which are themselves framed by two flow field materials 16, which are in turn framed by two bipolar plates 14. Furthermore, the electrolytic cell 10 also includes a gasket 13 (its presence already mentioned above), which is compressed between the two bipolar plates 14 of the electrolytic cell 10.

[0069] Since the membrane 11, the flow field material 16, and the electrodes 12a and 12b are known from the prior art, they will not be described in further detail here.

[0070] Since the two bipolar plates 14 of the electrolytic cell 10 are identical to each other, the following description of one bipolar plate 14 also applies to the other bipolar plate 14 of the same electrolytic cell 10. The bipolar plate 14 is made of a material capable of withstanding the predominantly corrosive environment inside the electrolytic cell 10.

[0071] The bipolar plate 14 is, for example, nickel-based and made of, for example, nickel or nickel alloy carbon steel.

[0072] The bipolar plate 14 is also configured to have two main surfaces: a first main surface facing the interior of the electrolytic cell 10 under discussion; and a second main surface facing the exterior of the electrolytic cell 10 under discussion.

[0073] As will be seen below, the bipolar plate 14 (along a plane of symmetry passing through the center of the bipolar plate under discussion) is asymmetrical. Therefore, within the same electrolytic cell 10, the first face of the described bipolar plate 14 is opposite to the second face of another bipolar plate 14 identical to the described bipolar plate. Within block 2, all bipolar plates 14 are oriented in the same manner.

[0074] In the following text, axis X and axis Y are defined as planes extending therein, forming one of the main surfaces of bipolar plate 14, and axis Z is defined as being orthogonal to the XY plane.

[0075] When the bipolar plate 14 is in the proper position in the electrolytic cell 10 (which itself is in the proper position in the electrolytic cell stack 1), the axis Z here coincides with the general direction A.

[0076] The thickness of bipolar plate 14 (along axis Z) is smaller than its other dimensions.

[0077] The bipolar plate 14 is configured to have a cross-section with a certain geometry (square, rectangle, disk, etc.) in the XY plane. Here, the bipolar plate 14 has a disk-shaped cross-section.

[0078] The outer periphery of the bipolar plate 14 is defined by the first region 21, the second region 22 and the third region 23.

[0079] Here, the first region 21 extends over the entire outer periphery of at least one of the main surfaces of the bipolar plate 14. Therefore, the first region 21 is a ring that forms the outer periphery of the main surface.

[0080] The first region 21 enables the bipolar plate 14 to withstand the dominant internal pressure within the electrolytic cell stack 1 and to improve the seal of the electrolytic cell 10 relative to the exterior of the electrolytic cell stack 1. Specifically, the first region 21 enables the increase of the strength of the bipolar plate 14, particularly its resistance to radial pressure loads applied to it (when the electrolytic cell 10 is arranged within the electrolytic cell stack 1). For example, the dimensions of the first region 21 are determined to meet standards suitable for pressurized vessels, such as standard PED 2014 / 68 / EU.

[0081] The first region 21 preferably has a texture. For example, the first region 21 includes grooves, stripes, irregularities, rough appearances, etc. on at least one of the main surfaces of the bipolar plate 14 and preferably on both main surfaces of the bipolar plate 14.

[0082] Conversely, the circular edges of the bipolar plate 14 (that is, the surfaces that join the two main surfaces of the bipolar plate 14 together) are very smooth, i.e., without texture.

[0083] Furthermore, the second zone 22 extends circumferentially so that its exterior is defined by the first zone 21. The second zone 22 is coaxial with the first zone 21.

[0084] Here, the second region 22 extends over the entire outer periphery of at least one of the main surfaces of the bipolar plate 14. Therefore, the second region 22 is a ring.

[0085] Zone 22 is smooth, meaning it has no texture.

[0086] The second zone 22 is located around the electrolyte supply channel and the channel for discharging gaseous products generated by electrolysis.

[0087] The thickness of the second region 22 (considered along axis Z) is less than the thickness of the first region 21. For example, the bipolar plate 14 is configured to have at least one shoulder between the first region 21 and the second region 22. Preferably, the bipolar plate 14 is configured to have two shoulders between the first region 21 and the second region 22. These two shoulders are identical (as in...). Figure 3a (As can be seen in the image) and formed on the two main surfaces of the bipolar plate 14. Therefore, the bipolar plate 14 is symmetrical in its first region 21 and its second region 22 in a centrally symmetrical plane parallel to the axes X and Y.

[0088] The narrowing section between the first zone 21 and the second zone 22 allows for different seals to be achieved between the two zones.

[0089] Furthermore, the third zone 23 extends circumferentially so that its exterior is defined by the second zone 22. The third zone 23 is coaxial with the second zone 22.

[0090] Here, the third region 23 extends over the entire outer periphery of the bipolar plate 14. The third region 23 is a ring.

[0091] The thickness of the third region 23 (considered along axis Z) is less than the thickness of the second region 22. For example, the bipolar plate 14 is configured to have at least one shoulder between the second region 22 and the third region 23.

[0092] Preferably, the bipolar plate 14 is configured to have a single shoulder between the second region 22 and the third region 23. This shoulder is formed on the first main surface of the bipolar plate 14, that is, on the surface facing the interior of the electrolytic cell 10. This shoulder allows for the accommodation of the membrane 11.

[0093] Preferably, the second region 22 and the third region 23 extend continuously to each other on the second main surface of the bipolar plate 14.

[0094] Therefore, there is no shoulder between the second zone 22 and the third zone 23 on the second main surface.

[0095] Therefore, it should be understood that the second surface of bipolar plate 14 does not have such a shoulder, so that the second surface of the other bipolar plate 14 of the electrolytic cell 10 under discussion also does not have such a shoulder. Thus, membrane 11 is arranged between the two bipolar plates 14 such that the membrane is contained only in the shoulder of one of the two bipolar plates 14.

[0096] Therefore, when considering the three regions mentioned above, the bipolar plate 14 is asymmetrical in the centrally symmetric plane parallel to axes X and Y (as in...). Figure 3a and Figure 3b as well as Figure 3c (It can be seen more clearly in the middle).

[0097] The third region 23 may be completely smooth (i.e., without texture), partially smooth, or completely textured. Preferably, the third region 23 has a texture on the first main surface of the bipolar plate 14. This makes it easier to hold the membrane 11 in place. On the first main surface, for example, the third region 23 may have grooves, stripes, irregularities, rough appearance, etc.

[0098] Preferably, the third region 23 is smooth on the second main surface of the bipolar plate 14.

[0099] Therefore, the thickness of the bipolar plate 14 (along axis Z) gradually decreases with the shoulder at the junction between the first region 21 and the second region 22, and also at the junction between the second region 22 and the third region 23. Thus, the bipolar plate 14 is thicker in its first region 21 than in its second region 22, and thicker in its second region than in its third region 23.

[0100] Region 21, Region 22, and Region 23 together form a convex ring 25. Therefore, the convex ring 25 forms the circumferential periphery of the bipolar plate 14.

[0101] Furthermore, the central portion 24 of the bipolar plate 14 extends such that its exterior is defined by the third region 23. The central portion 24 is coaxial with the third region 23.

[0102] The central portion 24 is solid. Therefore, the central portion 24 forms a circular platform.

[0103] The thickness of the central portion 24 (considered along axis Z) is less than the thickness of the third zone 23.

[0104] For example, the bipolar plate 14 is configured to have at least one shoulder between the third region 23 and the central portion 24. Preferably, the bipolar plate 14 is configured to have two shoulders between the third region 23 and the central portion 24. These two shoulders are identical and formed on two main surfaces of the bipolar plate 14.

[0105] The central portion 24 may optionally have at least one shoulder such that its thickness (thickness considered along axis Z) narrows in the direction of the center of the bipolar plate 14.

[0106] Therefore, the central portion 24 is the thinnest part of the bipolar plate 14 (thickness considered along axis Z).

[0107] The central portion 24 can be smooth or textured.

[0108] The central portion 24 acts as a current collector and transmits current to the flow field material 16 located on both sides of the central portion 24.

[0109] Furthermore, the bipolar plate 14 includes conduits 15 that extend entirely through it. These conduits 15 are dedicated to the supply of the electrolyte solution and the release of the electrolyte products.

[0110] For example, the bipolar plate 14 includes three to six conduits. These conduits are, for example, associated in pairs, with two pairs of conduits evenly distributed on the outer periphery of the bipolar plate 14. In this case, the bipolar plate 14 includes a pair of conduits 15 for supplying electrolyte, a first conduit 15 for discharging a first electrolysis product (a two-phase mixture of electrolyte and oxygen), and a second conduit 15 for discharging a second electrolysis product (a two-phase mixture of electrolyte and hydrogen).

[0111] For example, at least one of the catheters 15 is formed in the second zone 22. In this example, all the catheters 15 are formed in the second zone 22.

[0112] The conduit 15 may have a circular, oblong, or other different cross-sectional shapes. For example, at least one of the conduits 15 has an oblong cross-section. The conduit 15 is attached to the internal volume of the electrolytic cell 10 by a radial groove / counterhead hole extending from the conduit 15 in region 22 to the central portion 24.

[0113] In fact, compared to the convex ring 25, the central portion 24 does not actually bear large pressure. Therefore, the main function of the central portion 24 is to serve as a support for the components stacked within the electrolytic cell 10 (i.e., the flow field material 16, electrodes 12a and 12b, and membrane 11). Therefore, the forces on both sides of the central portion 24 are equal.

[0114] Therefore, the bipolar plate 14 has a specific geometry. The thickness of each of the aforementioned regions differs from one tenth of a millimeter to several millimeters. Due to the thermal expansion of the bipolar plate 14, the thickness of the aforementioned regions also has a variable value (due to thermal expansion, the variability of the thickness of each region also varies from region to region).

[0115] As indicated, the two bipolar plates 14 compress the spacer 13 between them within the electrolytic cell 10.

[0116] It should be noted that within the electrolytic cell stack 1, all bipolar plates 14 are separated in pairs by spacers 13 (because each bipolar plate 14 acts as the cathode of one electrolytic cell 10 and the anode of another adjacent electrolytic cell 10).

[0117] Advantageously, the two bipolar plates 14 compress the single gasket 13 between them.

[0118] Advantageously, all the gaskets 13 of the electrolytic cells 10 within block 2 are identical, such that the following description of one of the gaskets 13 also applies to the other gaskets 13 of the other electrolytic cells 10.

[0119] The main functions of the gasket 13 are as follows: i) to ensure the seal of each electrolytic cell 10 relative to the outside of the electrolytic cell stack 1; ii) to ensure the seal of the channel for conveying one gas generated in the block 2 relative to the channel for conveying another gas generated in the block 2; iii) to ensure the seal of the chambers that serve as the sites for the generation of the two gases in the electrolytic reaction, so as to isolate them from each other, and to ensure the seal relative to the channels just mentioned; iv) to act as an electrical insulating layer between two adjacent bipolar plates 14; and v) to define the thickness of the electrolytic cell 10 compressed along the Z direction.

[0120] Preferably, the gasket 13 is configured to have a square or rectangular cross-section (in the plane of the cross-section).

[0121] Therefore, gasket 13 is referred to as a "flat gasket".

[0122] Preferably, the gasket 13 is configured in a manner corresponding to the shape of the protruding ring 25 of the associated bipolar plate 14.

[0123] In this example, the gasket 13 is generally configured as a ring, and the associated bipolar plate 14 is in the form of a disc.

[0124] It should be noted that gasket 13 has multiple holes due to being punctured.

[0125] This ensures the supply of fluid to block 2 and the discharge of fluid from block 2. For example, the holes formed in the gasket 13 correspond to the holes formed in region 22 of the bipolar plate 14.

[0126] Gasket 13 is configured such that its diameter (the diameter of its cross section) is as constant as possible over all its inner and outer circumferences and / or its thickness (along axis Z) is as constant as possible over its entire section (and from one gasket 13 to another).

[0127] This enables the improvement of the efficiency of the electrolytic cell 10 in the electrolytic cell stack 1.

[0128] In particular, this allows the faces of the gasket 13 to be as parallel to each other as possible and to the opposite principal face of the bipolar plate 14.

[0129] Furthermore, this allows for improved sealing of the entire component.

[0130] The dimensional tolerances of gasket 13 depend on the intended application of the gasket (e.g., a thickness tolerance of + / - 0.1 mm). As described above, and as in Figure 3c As can be seen more clearly, the gasket 13 is compressed between two adjacent bipolar plates 14, and more precisely between the two outer peripheries of the opposing main surfaces of the bipolar plates 14, and more precisely between the two opposing convex rings 25 of the bipolar plates 14.

[0131] Due to the specific geometry of the bipolar plate 14 at its outer periphery (especially its convex ring 25), the bipolar plate 14 further deforms the gasket 13 by compressing it, so as to define and characterize the gasket 13 as three separate parts.

[0132] Conversely, the gasket 13 is not compressed between the central portions 24 of the two bipolar plates 14.

[0133] The diameter of the gasket 13 (along the cross section) is such that the gasket 13 extends from the lateral edge of the bipolar plate 14 to the attachment point between the third zone 23 and the central portion 24 (preferably extending beyond the third zone 23).

[0134] Therefore, each portion of the gasket 13 of the present invention achieves an individual sealing function and is characterized by a specific level of compression, which varies from portion to portion. The physical and mechanical result is that the thickness of the joint 13 is reduced depending on the portion in question.

[0135] Therefore, when the gasket 13 is in a neutral state, the gasket is in a conventional annular shape and has a substantially uniform initial thickness.

[0136] When the gasket 13 is compressed between the two bipolar plates 14:

[0137] - Between the first regions 21 of the two bipolar plates 14, the pad 13 has a corresponding textured first portion because the first portion matches the geometry of the first region 21;

[0138] Between the second regions 22 of the two bipolar plates 14, the gasket 13 has a corresponding smooth second portion, and the gasket 13 also has a greater thickness than its first portion;

[0139] Between the third region 23 of the two bipolar plates 14 and the membrane 11, the gasket 13 has a corresponding smooth and / or grooved third portion.

[0140] The gasket 13 is directly compressed between the two first zones 21 in its first part (without intermediate parts).

[0141] The gasket 13 is directly compressed between the two second zones 22 in its second part (without intermediate parts).

[0142] Conversely, the gasket 13 is not directly compressed between the two third regions 23 in its third portion. This is because the membrane 11 is also present between the two third regions 23. Therefore, the gasket 13 is directly compressed by one region of the third region 23 on one side of its surface and directly compressed by the membrane 11 on the other side, which itself is directly compressed by the third region 23 of the bipolar plate 14 on the other side.

[0143] The gasket 13 thus has a thickness in its third portion that is substantially less than the thickness of its second portion, wherein the membrane 11 fills the remainder of the space between the two third regions 23. A seal is thus achieved by the membrane 11.

[0144] Therefore, the gasket 13 is distributed across its three sections along its entire height (along axis X), and thus across the three zones of the convex ring 25.

[0145] Therefore, the portions of the electrolytic cell 10 located at the first region 21 of the two bipolar plates 14 and at the first portion of the gasket 13 prevent the electrolyte solution or gas from escaping from the electrolytic cell stack 1; in other words, these portions are specifically designed to ensure the electrolytic cell 10 is sealed relative to the external environment. For example, when measuring the seal using helium, the seal is ensured to be greater than or equal to 10. -3 mg per meter per second (mg / (m s), and preferably a seal greater than or equal to 10 -4 mg / (m s).

[0146] The first part is characterized by a texture on the bipolar plate 14, in which the gasket 13 is deformed. Through this deformation, the gasket 13 can specifically fill the hollow portion of the first part of the bipolar plate 14, and thus strengthen the seal of the electrolytic cell 10. This is because these textures constitute an additional barrier to gases and other substances reaching the outside of the electrolytic cell stack 1. This presence of texture also serves to promote friction between the electrolytic cells 10, and thus promotes the self-holding ability of multiple electrolytic cells 10 stacked to form a block 2. This advantage is increased when the block 2 is horizontal during operation.

[0147] For example, compression of gasket 13 causes gasket 13 to reach 94%, and preferably 78%, and more preferably 75% of its maximum thickness (along axis Z) in the first portion when the gasket is in its neutral state, lying flat on a flat surface without external constraints. The initial thickness is, for example, equal to or greater than 3.0 mm. Preferably, the initial thickness does not exceed 3.5 mm. As a variation, a thinner gasket may be used.

[0148] The second portion of the electrolytic cell 10, located at the second region 22 of the two bipolar plates 14 and the second part of the gasket 13, enables the prevention of any exchange between the channels for transporting hydrogen and oxygen in the electrolytic cell 10 or from the electrolytic cell 10 itself (starting from the third region 23 and the central portion 24) toward the channels.

[0149] For example, the compression of gasket 13 causes it to reach a thickness (along axis Z) of between 92% and 97% of its initial thickness (when the gasket is in a neutral state, lying flat on a flat surface without external constraints) in the second portion, and preferably 92% of its initial thickness. In all cases, the degree of compression of gasket 13 is less than in the first portion, and therefore it has a greater thickness than in the first portion.

[0150] The widening of gasket 13 between the first zone 21 and the second zone 22 allows for different seals to be produced between the first zone 21 and the second zone 22. The seal between the first zone 21 and the second zone 22 is of high quality under all circumstances.

[0151] The third portion of the electrolytic cell 10, located at the third region 23 of the two bipolar plates 14 and the third part of the gasket 13, enables the receiving of the membrane 11, as described above.

[0152] Therefore, this third part ensures the seal between the anode compartment and the cathode compartment of the electrolytic cell 10.

[0153] Therefore, it should be noted that in this third part, the membrane 11 and the gasket 13 are then compressed between the two bipolar plates 14: thus, in this part of the electrolytic cell 10, the gasket 13 is superimposed on the membrane 11.

[0154] This ensures a very good seal around the membrane 11 and around the membrane in the direction of the supply conduit and the fluid discharge conduit.

[0155] Therefore, the third portion of the gasket 13 defines a third compression zone, which is designed to hold the membrane 11 and ensure a seal of the membrane at its periphery.

[0156] For example, the compression of the gasket 13 causes the gasket 13 to reach a thickness (along axis Z) of 86% to 92% of its initial thickness (when the gasket is in a neutral state, lying flat on a flat surface without external constraints) in the third part, and preferably a thickness of 88% to 92% of its initial thickness, and more preferably a thickness of 90% of its initial thickness.

[0157] According to another aspect, gasket 13 is made of homopolymer or copolymer material, such as thermoplastic material.

[0158] For example, gasket 13 is made of a material of the polytetrafluoroethylene (PTFE or polytétrafluoroethylene) type (often abbreviated as PTFE, or more commonly known as Teflon (registered trademark)) or FKM (more commonly known as Viton (registered trademark)).

[0159] Preferably, the material is composed of polytetrafluoroethylene (PTFE) supplemented with at least one filler, or is based on PTFE, or is of a PTFE type. For example, the filler is glass fiber.

[0160] For example, the material is reinforced polytetrafluoroethylene (PTFE). For example, reinforced PTFE is PTFE reinforced with glass fiber, or PTFE reinforced with carbon fiber.

[0161] The characteristics of the gasket 13 are defined as follows:

[0162] -The material’s good behavior and good mechanical properties are maintained at the operating temperature of the electrolytic cell 10, even at high operating temperatures (typically on the order of 90 to 95 degrees Celsius), especially under long-term use.

[0163] - Tolerance to the corrosive environment inside the electrolytic cell 10, especially under long-term use;

[0164] - Excellent sealing properties;

[0165] - Excellent electrical insulation properties (provided by good resistance), even at operating temperatures and in contact with electrolyte solutions;

[0166] -Small creep allows for a good lifespan of the electrolytic cell stack 1 of the electrolytic cell 10;

[0167] - However, slight creep behavior is observed in order to optimally match the geometry of the area 21 where the gasket 13 is placed;

[0168] - Uniformity of thickness (along axis Z).

[0169] According to one option, the end gasket disposed between the first distribution plate 5 and the first substrate 3 is made of the same material as the gasket 13 of the electrolytic cell 10, which has just been described. The end gasket is, for example, the same as the gasket 13. The end gasket may optionally be made of a homopolymer or copolymer material, such as a thermoplastic material.

[0170] According to one option, the electrically insulating material layer between the first substrate 3 and the first distribution plate 5 is made of the same material as the end spacer disposed between the first distribution plate 5 and the first substrate 3. According to another option, the electrically insulating material layer between the first substrate 3 and the first distribution plate 5 is made of the same material as the spacer 13. The layer may optionally be made of a homopolymer or copolymer material, such as a thermoplastic material.

[0171] According to one option, the end gasket disposed between the second distribution plate 6 and the second substrate 4 is made of the same material as the gasket 13 of the electrolytic cell 10, which has just been described. The end gasket is, for example, the same as gasket 13. The end gasket may optionally be made of a homopolymer or copolymer material, such as a thermoplastic material.

[0172] According to one option, the patch on the inner surface of the first distribution plate 5 is either a material layer directly added to the first distribution plate 5 or formed by depositing powder, such as fluoropolymers and in particular ethylene-chlorotrifluoroethylene, such as products under the Halar brand manufactured by Solvay.

[0173] Due to the specific compression of the gasket 13 between the bipolar plates 14, the electrolytic cell 10 described herein has a very good seal.

[0174] It should be further noted that the electrolytic cell 10 is sealed by employing a single gasket 13, specifically, the gasket having three zones with different sealing and compression. The use of a single gasket 13 made of plastic (instead of the elastomers of the prior art) also makes it possible to improve the sealing of the electrolytic cell stack.

[0175] This is because the gasket 13 is better able to resist the predominantly corrosive environment inside the electrolytic cell stack 1, and even over long periods of time.

[0176] Therefore, the gasket 13 is made of a rigid material that withstands the high mechanical compression experienced by the electrolytic cell stack 1.

[0177] The electrolytic cell stack 1 also includes intermediate plates (generally indicated by 30) sandwiched within the element stack forming block 2. Each intermediate plate 30 includes an annular outer peripheral portion 31 and a disc-shaped central portion 32. The intermediate plate 30 has a thickness in which at least two electrolyte supply conduits, a first conduit for discharging a first electrolytic product, and a second conduit for discharging a second electrolytic product (all indicated by reference numeral 33) are formed, which are integrated with the supply network, the first discharge network, and the second discharge network of the electrolytic cell stack 1, respectively. The thickness of the intermediate plate 30 here has a value between a few millimeters and tens of millimeters, preferably between 50 mm and 70 mm. Each of the conduits 33 formed in the intermediate plate 30 opens near the opposite main surface of the outer peripheral portion 31 through an inlet orifice and an outlet orifice, and the length between these two orifices is greater than the thickness of the intermediate plate 30. Each conduit 33 includes a curved section 34 that engages an inlet orifice and an outlet orifice with each other, extending into a central portion 32 of the intermediate plate 30, and preferably near the center of the central portion 32. The curved section 34 thus has a U-shape with two branches extending parallel to the main surface of the intermediate plate 30 and having a first end engaged with each other by a bend, and an end opposite to the first end each having an end forming one of the orifices on the main surface of the intermediate plate 30. The intermediate plate 30 is produced from a conductive material by additive manufacturing, molding (e.g., using a sliding core die), forging, and then machining.

[0178] Intermediate plates 30 are distributed in block 2 such that two intermediate plates 30 are placed on both sides of the plurality of electrolytic cells 10. The plurality of electrolytic cells 10 preferably includes between twenty and fifty electrolytic cells 10.

[0179] The seal between each intermediate plate 30 and the electrolytic cell 10 surrounding the intermediate plate is ensured, for example, by two gaskets identical to those of gasket 13.

[0180] A method for assembling an electrolytic cell stack 1 will now be described.

[0181] According to the first step, sub-assemblies are constructed individually, each sub-assembly being formed by assembling two flow field materials 16 and two electrodes 12a, 12b on both sides of a bipolar plate 14. Strictly speaking, each sub-assembly constitutes two attached semi-electrolytic cells 10.

[0182] In the second step, the sub-assemblies are stacked sequentially, while being separated from each other by membrane 11 and gasket 13 to form the electrolytic cells 10 connected in series. The last electrolytic cell 10 at one end of block 2 is covered by a second distribution plate 6, which itself is covered by a second substrate 4, and the last electrolytic cell 10 at the other end of block 2 is covered by a first distribution plate 5, which itself is covered by a first substrate 3, thereby defining the electrolytic cell stack 1. An intermediate plate 30 is periodically inserted between two consecutive electrolytic cells 10. During this operation, it is important to note that conduits 33 and 15 are interconnected to form a supply network, a first discharge network, and a second discharge network.

[0183] During the third step, the newly assembled electrolytic cell stack 1 is compressed and placed using the pull rod 7, nut 8 and spring washer 9.

[0184] When the voltage at the terminals of each electrolytic cell 10 is different and the current is only connected to one or more points on the periphery of each distribution plate 5 and 6, this arrangement of thick distribution plates 5 and 6 and thin flat bipolar plates 14 allows for the uniformity of current in all electrolytic cells 10 of the electrolytic cell stack 1.

[0185] Furthermore, due to the specific shape and good clamping of each gasket 13, the bipolar plates 14 are highly parallel to each other within block 2. This further improves the uniformity of current in all electrolytic cells 10.

[0186] The assembly method should ideally allow each gasket 13 to specifically:

[0187] - It deforms according to the geometry applied by the bipolar plate 14 that clamps the gasket.

[0188] - Pressed into the texture of the first zone 21 to fill these textures,

[0189] - Intentionally and prematurely aging the material forming the gasket.

[0190] - To the greatest extent possible, eliminate the formation of gaskets containing plastic.

[0191] - To bring the material of the gasket into the range of elastic behavior (centered on the operating point of the electrolytic cell stack 1).

[0192] - To achieve the desired tightening value, the required seals and electrical contacts between the various components are combined to enable the desired energy performance.

[0193] The nominal operating point of the electrolytic cell stack 1 is, for example, 85 degrees Celsius at 3 MPa.

[0194] Of course, the invention is not limited to the described embodiments, but includes any variations that fall within the scope of the invention as defined by the claims.

[0195] (Multiple) end gaskets may be different from gasket 13.

[0196] The electrolytic cell stack 1 can be assembled in a different manner than that already described.

[0197] The electrolytic cell stack 1 can be used horizontally, vertically, or in any other position. The electrolytic cell stack 1 can be assembled horizontally, vertically, or in any other position. Preferably, the electrolytic cell stack 1 is assembled vertically and used horizontally.

[0198] A single conduit 33 associated with the supply of the electrolyte solution and a single conduit 33 associated with the discharge of each electrolytic product may exist. However, for redundancy in case one of the conduits 33 becomes blocked, it is preferable to have two conduits 33 associated with the supply of the electrolyte solution and / or two conduits 33 associated with the discharge of each electrolytic product. Typically, the distribution plates 5, 6 may contain only a single conduit 33, which opens at each end of its tip to a corresponding main surface in the main surface of the distribution plates 5, 6.

[0199] Similarly, for redundancy, it is preferable to have two grooves associated with each end of each conduit 33.

[0200] Each catheter 33 can be different from the others.

[0201] Each groove can be different from the others.

[0202] As mentioned above, the two distribution plates 5 and 6, each associated with one end of block 2, can be different from each other, rather than the same.

[0203] Distribution plates 5 and 6 may contain only a single reinforcing member, instead of the two reinforcing members already indicated.

[0204] The distribution plates 5 and 6 may include at least one conduit 33 that does not lead to the outer periphery of the associated main surface at least at one end of its end (and leads, for example, to the central area of ​​the main surface, such as to a reinforcement that may be present on the main surface).

[0205] For example, the distribution plates 5 and 6 may include at least one conduit 33 that leads at least one end of its ends to a reinforcement of the distribution plates 5 and 6. Optionally, the conduit 33 may open at least one end of its ends at a location sufficiently close to the outer periphery of one of the main surfaces to allow complete or near-complete drainage (drainage of liquids and / or gases) of the space present between the distribution plates 5 and 6 in question and the opposing substrates 3 and 4. Optionally, the conduit 33 may be formed as a reinforcement leading at a first end to a first main surface of the distribution plates 5 and 6, and at a second end to a reinforcement leading to a second main surface of the distribution plates 5 and 6, so as to establish communication between the two reinforcements.

[0206] The electrolytic cell stack 1 may include three electrodes: two end cathodes and one central anode.

[0207] One or more of the bipolar plates 14 may be arranged with conduits 15 having curved sections, so as to generate one or more intermediate plates 30 from this or these bipolar plates 14. In this case, the length of all or some of the conduits 15 formed in the intermediate plate 30 is greater than the thickness of the bipolar plate 14.

[0208] As a variant, one or both of the intermediate plates 30 may be formed by one or more of the distribution plates 5 and 6 extending between the end plates 3 and 4 and the adjacent electrolytic cell 10. In this case, the length of the conduit 15 formed in the distribution plates 5 and 6 is greater than the thickness of the distribution plates 5 and 6.

[0209] The spring washer 9 can be placed at both ends of the pull rod or at a single end of these ends, and / or can be replaced by any elastic compression member.

[0210] The U-shaped section does not necessarily extend all the way to the center of the middle plate.

Claims

1. An electrolytic cell stack (1), the electrolytic cell stack comprising two substrates (3, 4) sandwiching an element stack (2) including electrolytic cells (10), each electrolytic cell (10) comprising at least one electrolyte supply conduit, a first conduit for discharging a first electrolytic product and a second conduit (15) for discharging a second electrolytic product, the second conduit communicating from one electrolytic cell (10) to another electrolytic cell to form an electrolyte supply network, a first network for discharging the first electrolytic product and a second network for discharging the second electrolytic product along the electrolytic cell stack (1), characterized in that, The electrolytic cell stack (1) includes at least one intermediate plate (30) sandwiched in the element stack (2). The intermediate plate (30) has a certain thickness in which at least one electrolyte supply conduit, a first conduit for discharging the first electrolytic product, and a second conduit (33) for discharging the second electrolytic product are formed. The at least one electrolyte supply conduit, the first conduit, and the second conduit are integrated with the supply network, the first discharge network, and the second discharge network, respectively. Each of these conduits (33) formed in the intermediate plate (30) has a length greater than the thickness of the intermediate plate (30) and includes a curved section (34) that joins an inlet orifice on a first main surface of the intermediate plate and an outlet orifice on a second main surface of the intermediate plate. The curved section has a U-shaped shape with two branches that extend parallel to the main surface of the intermediate plate (30) and have a first end that joins each other through a bend. The opposite end has an end portion that forms one of the orifices on the main surface of the intermediate plate (30).

2. The electrolytic cell stack (1) as described in any of the preceding claims, comprising at least two intermediate plates (30) placed on both sides of the plurality of electrolytic cells (10).

3. The electrolytic cell stack (1) as described in claim 2, wherein, The plurality of electrolytic cells (10) includes between twenty and fifty electrolytic cells (10).

4. The electrolytic cell stack (1) as described in any one of the preceding claims, wherein, The intermediate plate (30) is a bipolar plate (14) of one of the electrolytic cells (10).

5. The electrolytic cell stack (1) as described in any one of claims 1 to 4, wherein, The intermediate plate (30) is a current distribution plate (5, 6) extending between the end plate (3, 4) and the adjacent electrolytic cell (10).

6. The electrolytic cell stack (1) as described in any one of the preceding claims, wherein, The component stack (2) is arranged vertically or horizontally.

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