Separator for electrically insulating electrolysis cells

Abstract

The invention relates to a separator (14) for the electrical insulation of cell component stacks (5, 6) of an electrolysis cell stack, and to an electrolysis cell stack with at least one separator (14). The separator (14) has a separator body with two opposing sides on which contact surfaces for electrolysis cells or end plates of cell component stacks (5, 6) are formed. The separator body is made entirely of an electrically insulating material or partially of different such materials.

Description

[0001] The invention relates to a separator for the electrical insulation of electrolysis cell stacks and to an electrolysis cell stack.

[0002] An electrolysis device uses electrical energy to produce substances in electrochemical reactions that are difficult or impossible to produce in larger quantities using purely chemical reactions. These electrochemical reactions take place in individual electrolysis cells of the device. Several electrolysis cells are arranged in an electrolysis cell stack (also called a cell stack), in which the individual cells are electrically connected. The individual electrolysis cells are connected in series, at least in sections. One side of each electrolysis cell represents the positive terminal, while the other side represents the negative terminal.

[0003] The electrochemical reactions can take place under pressure, so both the electrolysis cells and the cell stack must be pressure-resistant. For this purpose, the cell stack typically has a clamping device that clamps the stack and the electrolysis cells within it. Usually, the individual electrolysis cells are positioned against each other, forming the cell stack with two ends. An end plate or head plate is attached to each end, clamped by force-transmitting means such as tie rods, thereby exerting a compressive force on the electrolysis cells within the stack, clamping them against each other.

[0004] WO 2023 / 283170 concerns an electrolysis cell stack. This stack features a clamping device with two semi-cylindrical end plates. The flat ends of the end plates rest against the electrolysis cell stack and are connected by flat tension elements. This arrangement is intended to ensure the most uniform possible application of a large clamping force.

[0005] Based on this, the object of the invention is to provide a device which enables a larger number of contacting possibilities of an electrolysis cell stack while simultaneously increasing the mechanical stability of the electrolysis cell stack.

[0006] This problem is solved by a separator according to claim 1 and an electrolysis cell stack according to claim 28. Advantageous embodiments are the subject of the dependent claims and the description.

[0007] The separator according to the invention for the electrical isolation of electrolysis cells of an electrolysis cell stack comprises a separator body. This body consists of one or more electrically insulating materials. The separator body also has two opposing sides. The sides are designed with contact surfaces against which electrolysis cells or end plates of electrolysis cells or cell stacks can be placed. The two electrolysis cells or end plates adjacent to one separator are thus electrically separated from each other.

[0008] The separator body prevents current flow between two adjacent electrolysis cells or cell stacks separated by the separator. Electrolysis cells or cell stacks separated in this way can, individually, form cell sub-stacks of a larger electrolysis cell stack, which can be electrically connected in series or parallel. In this way, the separator allows for various electrical configurations of an electrolysis cell stack. The cell sub-stacks can also be clamped together by a single clamping device. Thus, the use of a separator increases the variability of electrolysis operation and enables additional degrees of freedom and design savings.

[0009] In some embodiments, the sides of the separator body on which the contact surfaces are formed can each be significantly larger than the distance between them. The separator body can, in particular, have a disc-like shape.

[0010] The contact surfaces of the separator body can be shaped, at least partially, to complement a surface on the respective electrolysis cells or end plates to which the contact surfaces can be attached. This means that the respective contact surface can be convex in areas where the surface is concave, concave where it is convex, or planar where it is planar, so that the respective contact surface, at least in the area where it is complementary, lies flat against the surface of the electrolysis cell or end plate in the unstressed state. An unstressed state is understood to be a state in which no compressive force acts on the separator body, i.e., in which the separator and the cell stacks are not yet clamped together to form a single electrolysis cell stack. Preferably, the entire contact surface of one side of the separator body is shaped to complement the surface.The separator can thus be arranged between electrolysis cells or end plates of electrolysis cell stacks, wherein the electrolysis cells or end plates in such an arrangement are positioned on opposite sides of the separator body, each resting against a contact surface of the separator body.

[0011] Depending on the surface, the contact surfaces of both sides can be identical, provided the surfaces themselves are similar. However, the contact surfaces can also be shaped differently depending on the surface to which they are attached.

[0012] The surfaces to which the contact surfaces are attached are typically the end faces of electrolysis cells or the end plates of a cell stack, each located at one end of the cell stack. The electrolysis cells and, if present, the end plates are typically arranged in a cell stack with their end faces parallel to each other in a row or stack. When the cell stacks and the separator are clamped together to form an electrolysis cell stack, the two cell stacks are also arranged parallel to each other in a row, so that the surfaces to which the separator rests are opposite each other in the electrolysis cell stack, meaning the separator is positioned between the surfaces. Accordingly, the contact surfaces on the separator body can be arranged opposite each other. This results in the separator body being subjected to the primary force transmission when the cell stacks are clamped together.The clamping force is applied directly to the separator body via the cell section stacks and efficiently transferred through the separator body.

[0013] The surfaces of the electrolysis cells or end plates, to which the contact surfaces can be attached, are generally planar, at least in the unstressed or unloaded state. The contact surfaces can also be planar. In particular, they can be arranged parallel to each other on opposite sides of the separator body, meaning the separator body can have a constant distance between the contact surfaces on opposite sides, and thus also a constant thickness. Therefore, when clamped between the cell stacks, the separator body is subjected to a surface pressure perpendicular to the contact surfaces, resulting in a particularly stable connection between the separator and the cell stacks.

[0014] Mechanical clamping of the electrolysis cells or cell component stacks and the separator to form an electrolysis cell stack during pre- and / or final assembly, as well as during electrolysis operation under pressure, can cause unwanted deformations, particularly bulges or protrusions (i.e., convex deformations), on the surface of the electrolysis cells or end plates against which the separator body's contact surfaces are pressed. In some embodiments, the contact surfaces of the separator body can be shaped to counteract such protrusions on the surface of the respective electrolysis cell or end plate by exerting a pressure force that is increased in areas with a protrusion compared to areas without. This pressure force is the counterforce that the separator body exerts against the compressive force during clamping or in the clamped state.To increase the contact force, the contact surfaces can be shaped complementarily to the surfaces of the electrolysis cells or end plates in their unstressed, undeformed state, or, in areas abutting the protrusions, they can have an excess of material compared to the unstressed, undeformed state, i.e., compared to the complementary shape. For this purpose, the contact surfaces can be planar, at least in some areas, or preferably convex. The separator body can also be lenticular, i.e., have convex contact surfaces on both sides.

[0015] In the case of convexly shaped contact surfaces, the apex of the convex contact surface can be located, in particular, in an area that, in the strained state, rests against a maximum bulge of the surface, i.e., in an area where the surface, in the strained state, exhibits a maximum deviation from its unstrained, undeformed state. A strained state is understood to be a state in which a compressive force acts on the surfaces and contact surfaces to clamp the cell stacks, i.e., they are subjected to compressive stress. The compressive force for clamping can, for example, be between 20 MPa and 50 MPa during acidic or alkaline electrolysis, especially high-pressure electrolysis.

[0016] Electrolysis cells and, if applicable, end plates can be pre-assembled into a cell stack without a separator, for example, for transport to the final assembly site. During final assembly, the cell stacks are clamped together with the separator to form an electrolysis cell stack. In this clamped state, the clamping force also acts on the separator body. The separator body thus counteracts deformations during final assembly if the electrolysis cells and end plates are undeformed after pre-assembly but before final assembly. Conversely, it can also compensate for deformations resulting from pre- and final assembly if the electrolysis cells and end plates are undeformed before pre-assembly.

[0017] In clamping devices with tie rods or anchors arranged outside the electrolysis cells and in an edge region of the end plates or head plates, usually rotationally symmetrical around the center of the end plates or head plates, a maximum bulge typically occurs near or in the center of the surface of the electrolysis cell and / or the end plate against which a contact surface is applied. Accordingly, the separator body may have the apex of the convex contact surface in the center of the respective contact surface. In embodiments, a planar region may also be provided at the apex, so that the contact surface in this region can more easily be applied to an undeformed, flat surface of the electrolysis cell or end plate.

[0018] The bulging in the center of the surfaces can be further exacerbated by overpressure in the electrolysis cells during electrolysis operation. The separator body can also counteract this deformation resulting from electrolysis. This is particularly advantageous when electrolysis in the cell stacks is carried out essentially continuously at constant electrolysis pressures.

[0019] While deformations caused by mechanical stress usually occur rotationally symmetrically around the longitudinal axis of the electrolysis cell stack, thermally induced deformations of the cell stacks or cell sub-stacks due to a temperature gradient in the direction of gravity usually affect an upper or lower region of the cell stack or cell sub-stacks. Cell stacks or cell sub-stacks with horizontally oriented longitudinal axes can, at operating temperatures above room temperature, expand more thermally in an upper region than in a lower region, causing the stack to widen longitudinally in the upper region. In certain embodiments, the contact surfaces of the separator body can be shaped in such a way as to counteract these thermally induced deformations of the electrolysis cells or end plates in a manner analogous to mechanically induced bulges.To increase the contact force in areas with thermal deformation, the contact surfaces can be shaped complementarily to the surfaces of the electrolysis cells or end plates in the undeformed state, which corresponds to the unstressed state at room temperature, or have an excess of material compared to the undeformed state in areas that are applied to the deformations.

[0020] The separator body can be wedge-shaped, in particular, so that the contact surfaces in an area located in the upper region of the electrolysis cells or, if applicable, end plates, have a greater distance from each other than in an area located in the lower region of the surfaces relative to the longitudinal axis of the cell stacks. Such separator bodies are especially advantageous when the electrolysis in the cell stacks is operated essentially continuously at constant operating temperatures, typically above 60°C.

[0021] With wedge-shaped separator bodies, however, the possibility of compensating for manufacturing tolerances or torsion of the cell stacks by shifting or rotating the separator body during assembly is eliminated. In preferred embodiments, the contact surfaces can therefore be arranged parallel to each other on opposite sides of the separator body and be rotationally symmetrical about an axis through their geometric centers of gravity. The separator body is also rotationally symmetrical, at least between the contact surfaces of the opposite sides. This allows the separator body to be rotated when clamped between the surfaces against which its contact surfaces can be applied, provided that the surfaces of the electrolysis cells or end plates are rotationally symmetrical about a longitudinal axis of the cell stacks.In a particularly preferred embodiment, the contact surfaces of the opposite sides can be planar and parallel to each other, so that the separator body can be moved and rotated for assembly along the surfaces of the electrolysis cells or end plates.

[0022] In one embodiment, at least one of the contact surfaces can be round, particularly circular, or polygonal. The shape of the separator body can correspond to the shape of the contact surface. Both contact surfaces can have the same shape or different shapes. These shapes can correspond to those of the electrolysis cells or end plates that are to be attached to the separator. That is, for electrolysis cells or end plates with, for example, a circular cross-section or circular end face, the separator body can be circular, particularly as a circular disk. A suitably adapted shape allows for particularly efficient force transmission. Furthermore, a shape adapted to the electrolysis cells offers the advantage that only minimal material is required to manufacture the separator while still ensuring continuous electrical insulation.

[0023] Preferably, the majority of a given side of the separator body also constitutes a corresponding contact surface. However, it is also possible that only a portion of a surface of the separator body constitutes a contact surface, with the remainder being an area that does not. The portion of the separator body that does not have a contact surface can be located both inside and outside an area bounded by a perimeter line that encompasses the contact surface. Furthermore, the area of ​​the separator body that does not have a contact surface can also have at least one opening or at least one free space.

[0024] Preferably, a circumferential line encompassing one of the contact surfaces includes an area that is equal to or larger than the surface of the electrolysis cell or end plate to be applied to the contact surface. The diameter of at least one contact surface can be equal to or preferably larger than the diameter of the surface of the respective electrolysis cell or end plate against which the separator body can be applied, so that, in the clamped state, the contact surface is at least partially flush with or projects beyond the outer circumference of the surface, i.e., has a projection that can preferably be formed around the entire circumference of the contact surface. If the respective surface against which a contact surface is applied is smaller than a maximum cross-section of the electrolysis cell or end plate on which the surface is formed, the diameter of the contact surface can, in embodiments, also be equal to the diameter of the cross-section of the electrolysis cell or end plate.The end plate should be the same size as, or larger than, the separator body in the clamped state, so that it is flush with or extends beyond the outer circumference of the electrolysis cell or end plate.

[0025] Such a separator body has the advantage that neither dirt nor other objects can penetrate or fall between the surfaces of the electrolysis cells or end plates, because the surfaces are covered by the mounting surfaces on their outer perimeter. Contaminants or objects that are electrically conductive or become conductive through moisture absorption can reduce the breakdown voltage for a voltage flashover and, in the worst case, lead to a voltage flashover between the electrically charged electrolysis cells or end plates during electrolysis operation. Such voltage flashovers are prevented by the separator body.

[0026] The overhang also has the advantage that manufacturing tolerances in the circumferential dimensions of the electrolysis cells or end plates can be compensated for during assembly and clamping of the cell stacks. For this purpose, the overhang in the plane of the contact surfaces is preferably larger than the manufacturing tolerance of the diameter of the surface of the electrolysis cells or end plate against which the contact surface is attached. However, the overhang is chosen to be small enough that, when clamping with tie rods or anchors, these can still be guided past the outer circumference of the separator body, thus maintaining a defined distance from the separator body. The separator body is therefore typically smaller in diameter than the end plates of the clamping device for the electrolysis cell stack.

[0027] In certain embodiments, the minimum thickness of the separator body, i.e., the minimum distance between the contact surfaces on opposite sides of the separator body, can be equal to or greater than a minimum creepage distance when clamped. If such a minimum distance is maintained, the separator body can be provided with openings, passages, gaps, or spaces of any shape, such as in segmented separator bodies, without compromising electrical safety during electrolysis operation due to creep arcing. Such a minimum thickness is also advantageous if the contact surfaces, as described above, are designed to be flush with the outer circumference of the surfaces to which they are attached, as this also prevents creep arcing at the edge of the separator body between the surfaces of the electrolysis cells or end plates.

[0028] The minimum creepage distance is the shortest path along a surface of the separator body where no creepage current exceeding 0.5 A, preferably 0.3 A, and particularly preferably 0.1 A, occurs between potentials at the end and beginning of the path, where the voltage difference between the potentials corresponds to a maximum voltage difference between the electrolysis cells or end plates, or their voltage-bearing surfaces to which the contact surfaces can be applied. The minimum creepage distance depends on the degree of contamination of the separator body surface and the tracking resistance of the material(s) from which the separator body is made. It can be determined as described in DIN EN 60664-1 2019-01.

[0029] In certain embodiments, the minimum thickness of the separator body in the clamped state can be at least equal to or greater than a minimum creepage distance for heavy fouling to increase safety. For typical electrolysis operation up to 2000 m above sea level with heavy fouling, a tracking current resistance of the separator body material below 400 V, and a maximum voltage difference between the surfaces of the electrolysis cells or end plates of up to 1.25 kV DC, the minimum creepage distance can be 20 mm; for a voltage difference of up to 1.5 kV DC, it can be 24 mm. Accordingly, the minimum thickness of the separator body can be at least 20 mm for up to 1.25 kV DC or at least 24 mm for up to 1.5 kV DC, depending on the maximum voltage difference.Heavy contamination, and therefore a high degree of contamination, means that conductive contamination or dry, non-conductive contamination that becomes conductive when exposed to moisture is present.

[0030] If the separator body, as previously described, is designed such that it projects beyond the surfaces of the electrolysis cells or end plates on its entire circumference, thus forming a continuous overhang, the shortest path along the surface of the overhang between the contact surfaces of opposite sides of the separator body—that is, from the contact surface of one side to the contact surface of the other—can correspond to at least a minimum creepage distance, particularly a minimum creepage distance for heavy fouling. This prevents flashovers at the overhang of the separator body. Furthermore, the minimum thickness of the separator body can be reduced because no fouling can penetrate between the surfaces of the electrolysis cells or end plates, and only leakage current flashovers at the overhang need to be prevented.

[0031] In some embodiments, the minimum thickness of the separator body in the clamped state can be equal to or greater than a minimum creepage distance for no or only slight contamination. This minimum creepage distance is typically smaller than the minimum creepage distance for heavy contamination, so the minimum thickness of the separator body can be less than the minimum thickness for heavy contamination. Reducing the thickness allows for material savings in the separator body without restricting design freedom with regard to perforations or openings. Furthermore, perforations, through-openings, gaps, or spaces of any shape, such as those found in segmented separator bodies, can be provided in the separator body without compromising electrical safety during electrolysis operation due to flashovers along these openings.

[0032] In a typical electrolysis operation up to 2000 m above sea level with no or only slight pollution, a tracking current resistance below 400 V and a maximum voltage difference between the surfaces of the electrolysis cells or

[0033] For end plates with a voltage difference of up to 1.25 kV DC, the minimum creepage distance can be 4.2 mm, and 5.5 mm for a voltage difference of up to 1.5 kV DC. Accordingly, the minimum thickness of the separator body can be at least 4.2 mm, preferably at least 5 mm, for voltage differences up to 1.25 kV DC, and at least 5.5 mm, preferably at least 6 mm, for voltage differences up to 1.5 kV DC, depending on the maximum voltage difference.

[0034] In embodiments where the separator body has no openings or gaps, such as spaces or crevices, in the area between the contact surfaces on opposite sides of the separator body, i.e., where it completely covers the surfaces against which it is placed, the minimum thickness of the separator body in the clamped state can also be less than a minimum creepage distance, particularly less than a minimum creepage distance with no or only slight contamination. Because the separator body has no openings or gaps, creep propagation along such openings between the opposite sides of the separator body is prevented. Creep propagation can only occur at the edge of the separator body.These problems are prevented by ensuring that the separator body's overhang is designed such that the shortest path between the surfaces of opposite sides of the separator body along the surface of the overhang corresponds to at least a minimum creepage distance, in particular a minimum creepage distance for heavy contamination. The longer this shortest path, the smaller the minimum thickness of the separator body can be.

[0035] The separator can consist of a single material, or it can be made of different materials. The material(s) must each be electrically insulating. Electrically insulating means that the material(s) have an electrical conductivity of at most 10⁻⁸ < S / m, preferably at most 10⁻¹⁰ < S / m, and particularly preferably at most 10⁻¹⁶ < S / m.

[0036] Preferably, the material(s) also exhibit high tracking resistance. Tracking resistance can be determined according to IEC standard 60112:2020 and expressed as a CTI (comparative tracking index) value, which corresponds to an upper voltage limit at which no tracking current exceeding 0.5 A occurs. Preferably, the separator material(s) have a CTI value or upper voltage limit of at least 200 V, more preferably at least 400 V, and most preferably at least 600 V. High tracking resistance reduces the minimum creepage distance, allowing for a smaller minimum separator thickness and material savings.

[0037] For a material with a tracking resistance of at least 400 V [JL1], the minimum creepage distance in a typical electrolysis operation up to 2000 m above sea level with a high degree of pollution and a maximum voltage difference of up to 1.25 V DC can be 18 mm; at a voltage difference of up to 1.5 V DC, it can be 21 mm. The minimum thickness of the separator body in the clamped state can accordingly be at least 18 mm at up to 1.25 V DC or at least 21 mm at up to 1.5 V DC in electrolysis operation, depending on the maximum voltage difference.

[0038] For a material with a tracking resistance of at least 600 V, the minimum creepage distance in typical electrolysis operation up to 2000 m above sea level with a high degree of pollution and a maximum voltage difference of up to 1.25 VDC can be 16 mm, and 19 mm for a voltage difference of up to 1.5 VDC. Accordingly, the minimum thickness of the separator body in the clamped state can be at least 16 mm for up to 1.25 VDC or at least 19 mm for up to 1.5 VDC in electrolysis operation, depending on the maximum voltage difference.

[0039] If the separator body is designed as described above, such that it is flush with the outer circumference of the electrolysis cells or end plates or projects beyond it, then no contaminants or objects can get between the electrolysis cells or end plates. This results in a very low degree of contamination or no contamination at all. Accordingly, the minimum thickness of the separator body can be reduced. In typical electrolysis operation up to 2000 m above sea level with a low degree of contamination or no contamination, a tracking resistance of at least 400 V, preferably at least 600 V, and a maximum voltage difference between the surfaces of the electrolysis cells or end plates of up to 1.25 kV DC, the minimum creepage distance can be 4.2 mm, and 5.5 mm at a voltage difference of up to 1.5 kV DC.The minimum thickness of the separator body in the clamped state can accordingly be at least 4.2 mm, preferably at least 5 mm, depending on the maximum voltage difference, at up to 1.25 kV DC or at least 5.5 mm, preferably at least 6 mm, at up to 1.5 kV DC.

[0040] Furthermore, the material or materials from which the separator body is made can exhibit high compressive strength. This compressive strength can be selected such that the separator body remains essentially undeformed in the clamped state, i.e., it is not compressed, deformed, or breaks. Essentially undeformed means that the distance between the contact surfaces of opposite sides of the separator body, and in particular the minimum thickness of the separator body, is at least 95%, preferably at least 98%, and most preferably at least 99% of the distance or minimum thickness in the unclamped state. The settling behavior during clamping is therefore so minimal that the additional clamping path required by the separator body is very small, and clamping during assembly is very simple.

[0041] Due to its high compressive strength, the separator can also transmit a large force between the electrolysis cells or end plates and counteract bulging on the surfaces to which the contact surfaces are applied. The minimum thickness of the separator body in the unstressed (i.e., unloaded) state is typically greater than the minimum thickness in the stressed (i.e., pressure-loaded) state by at least the amount by which the minimum thickness decreases due to stressing with maximum pressure compared to the unstressed state.

[0042] Preferably, the material(s) of the separator body has a compressive strength of at least 200 N / mm², more preferably a compressive strength of at least 350 N / mm². The compressive strength can be determined according to DIN EN ISO 604:2003-12.

[0043] In certain embodiments, the material(s) of the separator body can exhibit high flexural strength. Preferably, the material(s) can have a flexural strength of at least 300 N / mm², and particularly preferably at least 350 N / mm². The flexural strength can be determined according to DIN EN ISO 178:2019-08. The flexural modulus can be at least 18,000 N / mm², and preferably at least 20,000 N / mm², according to DIN EN ISO 178:2019-08.

[0044] The separator body can consist of a single monolithic component or of segments. The segments can be monolithic components or comprise subsegments. To accommodate any uneven force transmission, different materials can be used at different points on the separator.

[0045] The separator body can be made of a material with higher compressive strength than the rest of the separator body, particularly at points where maximum compressive forces occur due to the clamping and / or at points where it contacts areas with a maximally deformed surface. When clamped with externally guided tie rods or anchors, the compressive forces of the clamping act primarily on the outer surface of the electrolysis cells or end plates, so that deformations occur mainly in the center of the electrolysis cell or end plates, or on their surfaces against which the separator body can be applied. Accordingly, the separator body can have higher compressive strength in an outer area of ​​the contact surfaces and / or in the center of the contact surfaces than in the rest of the separator body. Higher compressive strengths can also be provided in areas with fasteners, openings, or recesses.In the case of separator bodies consisting of segments and / or subsegments, individual segments or subsegments may in particular be made of different materials.

[0046] According to one embodiment, the material of the separator body is at least partially a composite material, preferably a fiber-reinforced composite material, in particular a technical laminate according to DIN EN 60893-1:2004-12, in particular a glass fiber-reinforced epoxy resin material, in particular EP GC 202. These materials offer the material properties described as advantageous in the embodiment above.

[0047] In one design, the separator body is an annular disk. This disk has a central cavity and a continuous section of the separator body surrounding this cavity. Accordingly, the annular separator can have an annular contact surface on each of its two end faces. The size of this contact surface can be chosen so that the ring is flush with the outer circumference of the adjacent electrolysis cells or end plates, or it may protrude slightly. Particularly in clamping devices that are guided along the outside of the cell stack, the compressive forces are largely transmitted on the outer surface of the electrolysis cells or end plates. An annular disk separator body is therefore shaped to fully absorb these compressive forces transmitted on the outer surface while simultaneously requiring minimal material.

[0048] Preferably, the circular annular disc, without any overhang, has a ring width of at most 5%, preferably at most 3%, and particularly preferably at most 2%, of the outer diameter of the surface against which it can be placed. For a typical surface diameter between 1000 mm and 2000 mm, the circular annular disc can have a width of 50 mm to 100 mm, preferably 30 mm to 60 mm, and particularly preferably 20 mm to 40 mm. If an overhang is provided, for example to compensate for manufacturing tolerances, the ring width can be correspondingly larger by the amount of the overhang, in particular the amount of the manufacturing tolerance.

[0049] According to another embodiment, the separator body is formed from several segments. The segments may be spaced apart from each other or in contact with each other. Preferably, the separator body can be segmented such that, when the separator body is in contact with the electrolysis cells or end plates, i.e., in the installed state, the segmentation runs parallel or perpendicular to the longitudinal axis of the electrolysis cell stack. Electrolysis cell stacks are typically braced along their longitudinal axis and operated with their longitudinal axis in a horizontal orientation, as in electrolyzers with aqueous acidic or alkaline electrolytes (acidic or alkaline electrolysis), or in a vertical orientation, as in solid oxide electrolyzers.

[0050] The segments represent independent parts of the separator body. They can be manufactured, stored, and assembled independently of one another. This greatly simplifies the production of a complete separator. Furthermore, the use of segments makes it easy to construct different areas of the separator from different materials. This is particularly useful for accommodating the fact that varying forces can act on different parts of the separator. To save material and manufacturing steps, it can be advantageous for the segments to be spaced apart and not touching. However, in areas where particularly high forces are transmitted, such as the outer surface of the separator body, an arrangement where the segments touch can be beneficial.

[0051] In one embodiment, the segments are preferably made of different materials. In particular, the different materials each have a different compressive strength. By using different materials that differ in compressive strength, it is possible to selectively determine where the separator exhibits a material property that is advantageous for the overall design. Different materials can be provided within a single segment and / or different materials can be used from segment to segment.

[0052] Preferably, depending on the compressive force acting on the respective contact surface during clamping, and / or depending on any deformation of the contact surface in the clamped state, the segments exhibit a material with higher compressive strength in areas with higher compressive force and / or greater deformation than in areas with lower compressive force and / or lesser deformation. In clamping devices with external tie rods or anchors, it can be particularly advantageous for the segments to have increased compressive strength, i.e., a material with increased compressive strength, in an outer region of the separator body or the contact surfaces and / or in the center of the separator body compared to the other regions of the separator body.

[0053] Advantageously, segments within a single segment and / or from segment to segment can have materials with different flexural strengths. For example, depending on the compressive force applied to the respective contact surface during clamping and / or the deformation of the contact surface under clamping, they can exhibit higher flexural strength in areas with higher compressive force and / or greater deformation than in areas with lower compressive force and / or lesser deformation. In clamping devices with external tie rods or anchors, it can be particularly advantageous for the segments in an outer area of ​​the separator body or contact surfaces and / or in the center of the separator body to have increased flexural strength compared to the other segments of the separator body, i.e., a material with increased flexural strength.

[0054] Preferably, an inner segment of the separator body is a circular disk, while at least one outer segment is an annular disk, which is preferably arranged concentrically to the inner segment. Thus, the annular disk is arranged on the outside and the circular disk on the inside. The majority of the compressive forces are transmitted in the outer region of the annular disk. In the inner region of the circular disk, forces can arise that cause the electrolysis cells to bulge. The circular disk counteracts this bulging. The remaining free space in the radial direction between the circular disk and the at least one annular disk allows for material savings.

[0055] According to one embodiment, the circular annular discs, without any overhang, can have a ring width, i.e., a distance between the outer and inner diameters, of at most 5%, preferably at most 3%, and particularly preferably at most 2%, of the outer diameter of the surface against which they can be placed. If an overhang is provided, for example, to compensate for manufacturing tolerances, the ring width can be correspondingly larger by this overhang. The outer diameter of the circular disc can be between 5% and 80%, preferably between 10% and 50%, and particularly preferably between 10% and 30% of the outer diameter of the surface against which it can be placed.

[0056] Advantageously, the segments in the separator body are designed and arranged rotationally symmetrically. For example, several annular disks can be arranged concentrically to form the separator body. Preferably, a circular disk and at least one annular disk surrounding it can be arranged concentrically to form the separator body.

[0057] In some embodiments, the segments of a separator body can be divided into subsegments. For rotationally symmetrical segments, the division preferably runs radially, but circumferential division is also possible. Preferably, the segments are divided at uniform intervals around their circumference, with a new subsegment beginning every 60° in the circumferential direction. The segments can thus be composed of identically shaped subsegments, which are particularly easy to manufacture, transport, and assemble.

[0058] According to one embodiment, each pair of segments or subsegments has adjacent and complementary joining surfaces. The joining surfaces are advantageously arranged at locations on the separator body that do not represent contact surfaces. In the case of split segments, the joining surfaces between two adjacent subsegments can be located in the area of ​​the split or segmentation. For splits in a radial direction, these are typically the short sides of the subsegments.

[0059] The joining surfaces are preferably designed so that they can lie against each other across their entire surface, ideally over their entire area. This ensures a gap-free fit. Force transmission is thus possible perpendicular to the joining surfaces, for example, in the circumferential direction. Furthermore, a connection that covers as much of the entire surface as possible prevents the ingress of unwanted dust or similar contaminants that could cause leakage currents.

[0060] Preferably, the joining surfaces are positively interlocked, so that the movement of the subsegments relative to each other, preferably in at least two directions of movement, is blocked. Advantageously, a joining surface can have at least one undercut for this purpose. The joining surface with the undercut allows force transmission between the two respective subsegments to which the joining surface belongs. In particular, the undercut allows a force to be transmitted that has a component in the division direction and perpendicular to the division direction, especially also a tensile force.

[0061] The use of joining surfaces with undercuts allows different segments to be assembled from sub-segments and positioned as a whole between the respective electrolysis cells. These joining surfaces can be designed according to the hook-and-loop principle, where the undercuts interlock in a form-fitting manner. In addition to force transmission, the undercuts also minimize the ingress of dust or similar contaminants that could cause leakage currents between the joining surfaces.

[0062] The joining surfaces can be arranged continuously perpendicular to the contact surface or, preferably, be designed in a stepped or scarf configuration. With continuously perpendicular joining surfaces, the shortest path between the contact surfaces along a surface of the joining surfaces corresponds to the minimum distance between the contact surfaces or the minimum thickness of the separator body at the joining gap. This can be equal to or greater than a minimum creepage distance when clamped. This prevents any flashovers in the joining gap between the joining surfaces that could compromise electrical safety during electrolysis operation.

[0063] The term "seamless" means that the joining surfaces are complementary to each other and inclined to the contact surfaces, preferably at an acute angle with respect to the plane of the contact surface, in particular at an angle in the range between 5° and 40° inclusive, preferably between 10° and 30° inclusive.

[0064] Step-shaped means that the joining surfaces each have at least three sub-surfaces, each arranged at right angles or at an acute or obtuse angle to its adjacent sub-surface. Preferably, the perpendicular projections of the sub-surfaces onto the plane of the contact surfaces do not overlap in the plane of the contact surfaces. They are therefore arranged side by side. Because the projection surfaces do not overlap, it is ensured that segments or sub-segments can be brought into contact or joined with each other at the joining surfaces in a joining movement perpendicular to their contact surfaces. If the projections of the sub-surfaces overlap, the segments or sub-segments can be joined together in a joining movement parallel to the plane of the contact surfaces, provided there is sufficient clearance. This is possible, for example, if a segment or sub-segment is connected to the outer circumference of a second segment or sub-segment on its inner circumference.Subsegments are connected to this.

[0065] The surfaces of the joining surfaces can, for example, be arranged in a stepped pattern at right angles to each other, or in a sawtooth pattern at an acute or obtuse angle. Edges between the surfaces and / or edges adjacent to the contact surfaces can have a rounded contour in some embodiments.

[0066] By using slotted or stepped joining surfaces, the shortest path along the surfaces of the joining surfaces is increased compared to continuously vertical joining surfaces. Preferably, this shortest path in the clamped state is greater than a minimum creepage distance along the surface of the joining surfaces between the contact surfaces, in particular greater than or equal to a minimum creepage distance with low or no contamination. As described, this minimum creepage distance can be, for example, 4.2 mm at 4.2 mm for electrolysis operation up to 2000 m above sea level with low or no contamination, with a tracking current resistance of at least 400 V, preferably at least 600 V, and a maximum voltage difference between the surfaces of the electrolysis cells or end plates of up to 1.25 kV DC, or 5.6 mm at a voltage difference of up to 1.5 kV DC.The shortest path length can therefore be at least 4.2 mm, preferably at least 5 mm, depending on the maximum voltage difference, up to 1.25 kV DC, or at least 5.6 mm, preferably at least 6 mm, up to 1.5 kV DC. This prevents flashovers from occurring in the joint gap. The minimum distance between the contact surfaces or the minimum thickness of the separator body can thus be reduced despite the joint gaps, without compromising electrical safety.

[0067] The minimum thickness of the separator body can then be less than a minimum creepage distance along the surface of the joining surfaces between the opposing contact surfaces. In particular, it can be less than the minimum creepage distance by up to an amount by which the shortest path along the surfaces of the joining surfaces is increased compared to the minimum creepage distance. That is, if the length of the shortest paths along the surfaces of the joining surfaces in the joining gap increases by a certain amount compared to the minimum creepage distance, for example, due to a stepped or scarfed design of the joining surfaces, then the minimum thickness of the separator body can be reduced by a maximum of this amount compared to the minimum creepage distance without compromising electrical safety through flashovers in the joining gap.Reducing the thickness of the separator body has the advantage of saving material in the separator body and making it easier to assemble the separator body and mount the cell stack.

[0068] In some embodiments, the circumferential surfaces of through-openings or perforations extending from one side to the opposite side between opposing sides of the separator body, where the contact surfaces are formed, can also be stepped, chamfered, and / or have projections or recesses, such that the shortest path along the surface of these surfaces between the opposing sides of the separator body is increased compared to the minimum creepage distance, i.e., greater than the minimum creepage distance. This allows the minimum distance or minimum thickness of the separator body to be reduced by up to the amount by which the length of the shortest path exceeds the minimum creepage distance, without compromising electrical safety through flashovers on the respective surfaces.

[0069] Chamfered means that the surface is formed at an oblique angle to an adjacent contact surface. The surface can be chamfered only in the area of ​​the edge between the surface and the contact surface, i.e., the edge can be chamfered; however, the entire surface can also be chamfered relative to the contact surface. In some embodiments, the edge between the surface and the contact surface of each side can also be chamfered on both opposite sides of the separator body, segment, or subsegment.

[0070] In one embodiment, a circumferential surface of a segment is stepped or chamfered and / or has at least one circumferentially closed projection and / or at least one circumferentially closed recess or groove. "Closed around the circumference" means that the projection, recess, or groove has no beginning and no end, i.e., it is a continuous, self-contained feature. The recess or groove forms a depression on the respective circumferential surface. A circumferential surface can be a surface on an inner outer circumference of a segment or on an inner circumference of a segment. "Inner" means that the circumferential surface is not located at the edge of the separator body or on a projection of the separator body, but rather, when the separator body is placed against the electrolysis cells or end plates, it is located between the electrolysis cells or end plates.

[0071] Both stepped or chamfered surfaces, as well as projections, recesses, or grooves, increase the length of the shortest path along the surface of the circumferential area between the contact surfaces of opposite sides of the separator body. Accordingly, the minimum thickness of the separator body, segment, or subsegment can be reduced without compromising electrical safety through creepage arcs. For particularly simple, especially subtractive, manufacturing, the recesses or grooves are preferably formed on the circumferential surfaces in the area of ​​the contact surfaces, i.e., at an edge between the circumferential surface and the contact surface.

[0072] Advantageously, the separator body has a projection. At least one side of the separator body can have a free surface located beyond a circumferential line that defines the contact surface of that side. The free surface can be an extension of the contact surface, i.e., it can be formed in the plane of the contact surface. Advantageously, at least one circumferentially closed projection and / or at least one circumferentially closed recess or groove can be arranged on the free surface. While in the previous embodiment the contact surface is divided into at least two parts by the circumferential recess, in this embodiment the circumferential projection or the circumferential recess divides the free surface into two parts.

[0073] The open area at the overhang represents an area of ​​the separator body outside that part of the separator body where the mounting surfaces are located.

[0074] This is particularly relevant for an area that, in a stressed state, protrudes beyond the adjacent electrolysis cells. The projection, recess, or groove on the free surface thus prevents the occurrence of leakage currents, regardless of the separator body's orientation, by increasing the length of the shortest path along the surface of the overhang between the surfaces of the separator body's opposite sides. Consequently, the minimum thickness of the separator body, segment, or subsegment can be reduced without compromising electrical safety through flashovers. Projections and recesses offer the advantage of increasing the length of the shortest path along the surface of the overhang without increasing the length of the overhang itself, i.e., the diameter of the separator body.This saves material in the separator body and makes handling the separator body easier due to the associated weight reduction.

[0075] Recesses or grooves have the advantage over protrusions that they can be manufactured using material-saving methods, such as subtractive manufacturing, and exhibit less contamination. In its ready-to-use assembled state, the electrolysis cell stack can be arranged with its longitudinal axis horizontally, so that the separator body is positioned with its contact surfaces oriented vertically (the surface normals are oriented horizontally). While contaminants falling from above (i.e., vertically), which could result in leakage currents, can accumulate on the outer circumference of the separator body and possibly on protrusions, these contaminants cannot reach the recessed surfaces of the recess or groove. The recess or groove...The groove therefore particularly advantageously prevents the formation of a continuous layer of contamination, especially if it is designed as a circumferential closed groove, and thus reduces the occurrence of creepage currents.

[0076] In some embodiments, the projection can have an L- or T-shaped cross-section. Due to a protrusion perpendicular to a contact surface, the projection extends beyond the outer circumference of the electrolysis cell or end plate when the separator body is placed against its surface. This further reduces the ingress of contaminants between the contact surface and the surface of the electrolysis cell or end plate. It is particularly advantageous for the projection to be arranged on a larger diameter of the separator body than a recess or groove, so that the projection covers both the recess or groove and the gap between the separator body and the electrolysis cell or end plate.

[0077] If the separator body has no openings or gaps, such as spaces, cracks, or segmentations, between its opposing sides, so that the surfaces against which the separator body is placed are completely covered by the separator body, the minimum thickness of the separator body may be less than a minimum creepage distance due to the increased path length along the surface of the overhang. In particular, the minimum thickness may be less than the minimum creepage distance by up to the amount by which the shortest path length along the surfaces of the overhang between the contact surfaces is increased compared to the minimum creepage distance at the overhang. That is to say,If the shortest path along the surfaces of the overhang is increased by a certain amount by a projection or preferably by a groove or recess compared to the minimum creep distance, the minimum thickness of the separator body can be reduced by a maximum of this amount compared to the minimum creep distance without compromising electrical safety through creep arcs on the overhang.

[0078] If, on the other hand, the separator body has openings or perforations, such as gaps or slots, extending from one side of the separator body to the opposite side where the contact surfaces are formed, the minimum thickness of the separator body can be reduced compared to the minimum creepage distance, provided that the shortest path along the surface of the protrusion and the shortest paths in the openings and perforations are increased compared to the minimum creepage distance. In particular, the minimum thickness can be reduced by at most the smallest of the amounts by which the shortest path along the surfaces of the protrusion and the shortest paths along the surfaces of openings or perforations, especially along the surfaces of joining surfaces, are each increased compared to the minimum creepage distance.If the shortest path along the surfaces of the overhang is increased due to a groove or recess, the minimum thickness may be reduced, particularly with respect to a minimum creep distance for low or no contamination.

[0079] According to one embodiment, the separator, in particular the separator body, has at least one fastening means for positioning and / or attaching it to an electrolysis cell or end plate, such as screws, threaded inserts, positioning pins, or bores for these. The fastening means allow electrolysis cells or end plates to be positioned and / or attached to the separator. This ensures stable mounting not only by applying external pressure.

[0080] In another embodiment, the separator body, particularly at its edge and / or overhang, has an average surface roughness of at most 0.1 mm, preferably at most 0.05 mm. Such a smooth surface reduces the adhesion of contaminants and facilitates easy cleaning. This allows the minimum creep distances to be reduced to the minimum required for no or only minimal contamination.

[0081] The electrolysis cell stack according to the invention comprises at least two electrolysis cells, between which a separator according to one of the preceding embodiments is arranged. The electrolysis cell stack can therefore consist of two electrolysis cells separated by a separator. Alternatively, several electrolysis cells can be arranged one behind the other to form a cell sub-stack, wherein several cell sub-stacks can each be separated by a separator and clamped together to form the electrolysis cell stack. In embodiments, the cell sub-stacks can each have end plates at their ends for assembly and transport, such that an end plate rests against the separator and is electrically connected to the electrolysis cell at the end of the respective cell sub-stack. End plates at the ends of the electrolysis cell stack can be designed as end plates of a clamping device or rest against such an end plate.

[0082] The separator makes it possible to create electrolysis cells with many cell sub-stacks that can be contacted differently. Such an electrolysis cell stack, which includes at least one separator, is therefore characterized by its ability to allow for a flexible electrical configuration of the contained electrolysis cells and cell sub-stacks. Separate electrolysis cells or cell sub-stacks can be connected in series or in parallel through appropriate wiring. A series connection of two groups of several cell sub-stacks connected in parallel is also possible. By providing, for example, a switch, different cell sub-stacks can be isolated from the rest of the circuit of an electrolysis cell stack.By using a separator according to the invention, the adaptability of an electrolysis cell stack to different locations or operating modes of electrolysis, such as demand-dependent full or partial load operation, in which all or only individual cell sub-stacks are operated, is thus increased.

[0083] According to one embodiment of the electrolysis cell stack, the arrangement of electrolysis cells and separator, or electrolysis cells and separators, is clamped by a common clamping device. The clamping device can be located on the outermost electrolysis cells or end plates of the electrolysis cell stack and exerts a compressive force on the intermediate electrolysis cells and separators. Depending on the design of the clamping device, which may include, for example, tension rods or tie rods attached to end plates and running along the outside of the cell stack, the compressive force can be such that the outer areas of the electrolysis cells are primarily subjected to pressure. This results in a compressive load, particularly in the outer areas of the electrolysis cells or end plates and the separator body.Particularly at the points where the compressive force is transmitted, the separator body, according to the previously described designs, is capable of withstanding high compressive forces. Furthermore, this high compressive strength prevents the electrolysis cells or, if present, end plates in contact with the separator from bulging. This has the advantage of improving the tightness of connections that may be provided on the electrolysis cells and / or end plates, for example, for media supply or discharge, as well as the sealing between the electrolysis cells themselves.

[0084] The invention is explained below with reference to exemplary embodiments illustrated in the drawings. These show: Fig. 1 schematically shows an example of an electrolysis device with a separator and two cell stacks connected in series, Fig. 2 schematically shows an example of an electrolysis device with a separator and two cell stacks connected in parallel, Fig. 3 schematically shows another example of an electrolysis device with a separator and two cell stacks connected in series, Fig. 4 schematically shows another example of an electrolysis device with a separator and two cell stacks connected in parallel, Fig. 5a shows a schematic sectional view of embodiments of separators, Fig. 6 shows a circular disk-shaped separator, Fig. 7a shows an annular disk-shaped separator, Fig. 7b shows a separator formed from an annular disk and a circular disk, Fig. 7c shows a separator formed from two annular disks and a circular disk, Fig. 8 shows a separator with a segment divided into subsegments, Fig.9. Another separator with a segment that is divided into subsegments and has undercuts on the joining surfaces between the subsegments, Fig. 10a. Detail view of a joining surface of two separator body subsegments, Fig. 10b. Detail view of a joining surface of two separator body subsegments with undercuts, Fig. 10c. Detail view of a joining surface of two separator body subsegments with undercuts, Fig. 10e. Detail view of a joining surface of two further separator body subsegments with undercuts, Fig. 11a. Detail view of a separator having a circumferential closed groove on a clearance surface and a contact surface, Fig. 11b. Detail view of a separator having a circumferential closed projection on a clearance surface and a circumferential closed groove on a circumferential surface. and Fig.12 Minimum creepage distances depending on the voltage difference, the degree of pollution and the tracking resistance of the separator body.

[0085] Figure 1 Figure 1 shows an electrolysis device 1. The electrolysis device 1 comprises an electrolysis cell stack with two cell sub-stacks 5, 6 consisting of several electrolysis cells 7 connected in series and a separator 14, which is arranged between the cell sub-stacks 5, 6 in contact with them. The cell sub-stacks 5, 6 can be supplied with direct current for electrolysis operation via a power supply 2. For this purpose, the cell sub-stacks 5, 6 can be connected to each other in series and / or parallel in a circuit between a positive terminal 3 and a negative terminal 4 of the power supply 2, or can be switched between these configurations. Figure 1 Figure 1 shows a series circuit in which both cell sub-stacks 5, 6 are connected to the power supply 2.

[0086] The positive terminal 3 of the power supply 2 is connected to an inner end of the cell stack 5. The negative terminal 4 is connected to an inner end of the cell stack 6. The inner end is defined as the end of each cell stack 5 or 6 that is closest to, or in contact with, the separator 14.

[0087] At their outer ends, the cell stacks 5, 6 are electrically connected to each other via at least one electrical conductor 12, thus closing the circuit to the power supply 2. The outer ends are defined as those ends of the cell stacks 5, 6 that face away from the separator 14 and are located at the opposite ends of the electrolysis cell stack to which the cell stacks 5, 6 and the separator 14 are clamped.

[0088] Electrically conductive end plates (not shown) can be arranged at the inner and outer ends of the cell stacks 5, 6. These end plates are electrically connected to the electrical pole of the electrolysis cell at the respective end of the cell stack 5, 6, thus forming the ends of the cell stacks 5, 6. End plates 70 typically serve for the assembly and transport of the pre-assembled cell stacks 5, 6. Media can be supplied and / or discharged via the end plates; that is, the end plates can be designed such that liquid or gaseous media, such as oxygen and / or hydrogen in water electrolysis, can be discharged from the electrolysis cells and / or supplied via media connections on the end plates, such as an electrolyte in water electrolysis.

[0089] The cell stacks 5 and 6 can be further subdivided into substacks (not shown). The substacks can also have electrically conductive end plates at their ends, which can be the end plates of cell stacks 5 and 6, respectively, located at the inner and outer ends of the cell stack. The substacks are arranged in series with the respective cell stack and are electrically connected in series. Two end plates of opposite polarity touch each other. This subdivision into substacks simplifies the manufacturing, transport, and assembly of the cell stacks.

[0090] The clamping of the cell stacks 5, 6 and the separator 14 to the electrolysis cell stack can be achieved via a clamping device comprising two electrically conductive end plates 8, 9 and several tie rods or anchors 10, 11. The end plates 8, 9 are arranged at opposite, outer ends of the electrolysis cell stack. End plate 8 rests against cell stack 5, while end plate 9 rests against cell stack 6. The tie rods or anchors 10, 11 are arranged externally between the end plates 8, 9, i.e., outside the electrolysis cells. By tightening nuts on the tie rods or anchors 10, 11, the end plates 8, 9 can be pressed against the cell stacks 5, 6, and a compressive force can be applied via the end plates 8, 9 to the cell stacks 5, 6 and the separator 14 arranged between them, so that they are held together under pressure. The end plates 8, 9 can have connections for media supply and / oror removal. To save material, the end plates at the outer ends of the electrolysis cell stack can also each be designed as head plates 8, 9 and replace them, i.e. they can be the head plates 8, 9.

[0091] The outer ends of the cell stacks 5, 6 are electrically contacted with the end plates 8, 9. Therefore, the outer ends of the cell stacks 5, 6 can also be connected to each other via an electrical conductor 12, which electrically connects the end plates 8, 9. The conductor 12 can, for example, be a power cable or busbar that is not part of the clamping device. In this case, the tie rods or anchors 10, 11 are electrically insulated from the electrically conductive end plates 8, 9, and thus also from the outer ends of the cell stacks 5, 6. For safety, an earth connection 13 can be provided, which is connected to the conductor 12, an end plate 8, 9, or an end plate via a switching element.

[0092] When contact is made via the end plates 8, 9, the electrical conductor 12 can advantageously also be at least one of the tie rods or anchors 10, 11, which is then electrically connected to the end plates 8, 9. Additional electrical conductors that are not part of the clamping device, such as separate power cables or busbars, are then unnecessary. This means that the electrical connection between the outer ends of the cell stacks 5, 6 is then made exclusively via the electrically conductive tie rods or anchors 10, 11.

[0093] A separator 14 according to the invention is arranged between the cell stacks 5, 6. It ensures that the cell stacks 5, 6 are electrically isolated from one another. This allows the cell stacks 5, 6 to be electrically connected in series, even though they are clamped by a common clamping device. To enable force transmission between the cell stacks 5, 6, the separator body of the separator 14 is made of a flexurally and compression-resistant material. Its contact surface rests against the surfaces of the inner ends of the cell stacks 5, 6.

[0094] These surfaces can typically be surfaces on the end faces of the electrolysis cells of the respective cell stacks 5, 6, or, if end plates are present at the inner ends of the cell stacks 5, 6, surfaces on the end faces of the end plates of the cell stacks 5, 6.

[0095] The contact surfaces of the separator body are typically shaped complementarily to the surfaces to which they are attached. However, they can also have an excess of material in areas that contact mechanically and / or thermally deformed points on the surfaces, so that when the cell stacks 5, 6 are clamped, an increased contact force is exerted on these points and the deformation is counteracted.

[0096] The separator body can consist of a single, continuous, seamless component, i.e., be monolithic, or it can consist of segments. The segments can be monolithic components or consist of subsegments. The material(s) from which the separator body is made preferably has a compressive strength of at least 200 N / mm², more preferably at least 350 N / mm², and a flexural strength of at least 300 N / mm², more preferably at least 350 N / mm². It is preferably a composite material, in particular a fiber-reinforced epoxy resin, such as EP GC 202.

[0097] The material or materials from which the separator body is made also have an electrical conductivity of at most 10⁻⁸ < S / m, preferably at most 10⁻⁰ < S / m, particularly preferably at most 10⁻⁶ < S / m, and advantageously have a tracking resistance (CTI value) according to DIN EN IEC 60112:2020 of at least 200 V, preferably at least 400 V, particularly preferably at least 600 V.

[0098] Tracking resistance indicates the voltage, measured in volts, up to which the material shows no tracking (becoming conductive under voltage) when 50 drops of standardized electrolyte solutions are applied. The measurement is taken on an etched surface, with one drop falling between two platinum electrodes every 30 seconds. The failure criterion is a tracking current of 0.5 A, but stricter criteria, such as 0.3 A or 0.1 A, can also be specified. Details of the measurement procedure are known from DIN EN IEC 60112:2020.

[0099] Due to high tracking resistance, the minimum creepage distance along a surface of the separator body between the contact surfaces on opposite sides of the separator 14 is reduced, as for example in Figure 10 This allows the separator body to be manufactured with a smaller minimum thickness. Furthermore, the length of the shortest path along the surface of the separator body between the contact surfaces of opposite sides of the separator body can be increased by means of stepped, scarfed, or chamfered surfaces, as shown, for example, in Figures 8c to 8e, and / or by means of overhangs, projections, and / or recesses, as shown, for example, in Figures 9a and 9b. This also allows the separator body to be manufactured with a smaller minimum thickness, in particular a minimum thickness that is less than the minimum creepage distance for the respective electrolysis operation.

[0100] For positioning or fastening the separator body to the surfaces of the electrolysis cells or end plates, the separator may be provided with 14 fastening means, such as screws, threaded inserts, positioning pins and / or bores for these.

[0101] Figure 2Figure 15 shows another electrolysis device 15. Electrolysis device 15 includes the separator 16 and differs from electrolysis device 1 in that the two cell stacks 17 and 18, which are separated from each other by the separator 16, are connected in parallel in the power supply circuit. In this configuration as well, the separator 16 serves to distribute the forces applied by the clamping device as evenly as possible. In particular, the separator 16 prevents the electrolysis cells and any end plates of the cell stacks 17 and 18 from bulging. This increases the tightness of the electrolysis cells and, in the case of media supply and / or discharge via the end plates, also helps to ensure that the media connections on the end plates are not deformed and remain leak-proof.

[0102] The electrolysis cell stacks and cell sub-stacks 5, 6; 17, 18 in the embodiments of the Figures 1 and 2The cells are oriented horizontally in the world coordinate system with their longitudinal axes, as is common, for example, for electrolysis with aqueous acidic or alkaline electrolytes, particularly for alkaline pressure electrolysis. In electrolysis devices with solid oxide electrolytes, electrolysis cell stacks and cell sub-stacks can be operated in a vertical orientation instead of a horizontal one. They can also have a separator 14, 16 between the cell sub-stacks. The separator 14, 16 according to the invention can be used in horizontally or vertically oriented electrolysis devices for the electrical insulation of cell sub-stacks and the mechanical stabilization of the electrolysis cell stack.

[0103] In the Figures 1 and 2The inner ends of the cell stacks 5, 6; 17, 18 are each permanently connected to the poles 3, 4 of the power supply 2 via electrical conductors. However, a switching device can also be provided with which cell stacks 5, 6; 17, 18 can be disconnected from the circuit to the power supply 2. Figure 3 shows the electrolysis device 1 from Figure 1Figure 80 shows an embodiment of a switching device comprising a switch 80 and a switchable conductor 90. In the figure, the switchable conductor 90 is shown in perspective behind the insulator 14 and typically does not touch it, i.e., it is not connected to the insulator 14. The switch 80 has switching elements S1 to S4 and S7. Switching elements S1 and S2 are each arranged between an inner end of a cell stack 5, 6 and a pole 3, 4 of the power supply 2 and are configured to open and close the electrical connection between the inner end of the cell stack 5, 6 and the power supply 2. Switching elements S3 and S4 are configured to open and close the electrical connection between the switchable conductor 90 and the power supply 2.The switchable conductor 90 is connected via switching elements S3 and S4 to the electrical lines between switching elements S1 and S2 and the power supply, and is also electrically connected to conductor 12. The conductor 12 can be connected to the grounding point 13 via switching element S7.

[0104] The cell sub-stacks 5, 6 in Figure 3 They have end plates 70 at their ends, which are electrically connected to the electrical pole of the electrolysis cell at the respective end of the cell stack 5, 6 and thus form the electrical poles of the cell stacks 5, 6. In the electrolysis device of the Figure 3The conductor 12 connects opposite poles of the cell stacks 5, 6. The tie rods 10, 11 are electrically insulated from the end plates 8, 9 and thus also from the cell stacks 5, 6 and end plates 70, so that the electrical connection between the outer ends of the cell stacks 5, 6 or their poles is exclusively via the conductor 12, which can be, for example, a power cable or a busbar, and not via the tie rods or tie rods 10, 11.

[0105] In the Figure 3The first switching state is shown, in which the first cell sub-stack 5 is disconnected from the circuit between poles 3 and 4 of the power supply 2. For this, switching elements S1, S4, and S7 are open, and S2 and S3 are closed. Analogously to the first switching state, in a second switching state, the second cell sub-stack 6 can be disconnected from the circuit by opening switching elements S2, S3, and S7, and closing S1 and S4. In an initial state, both cell sub-stacks 5 and 6 can be connected in series in the circuit by closing all switching elements. Furthermore, in an off state, both cell sub-stacks 5 and 6 can be disconnected from the power supply 2 by opening all switching elements.

[0106] In the Figure 4A first switching state for a parallel circuit is shown. Switch 80 comprises switching elements S5, S6, and S7. Switching elements S5 and S6 are each arranged between an inner end of a cell stack 17, 18 and the positive terminal 3 of the power supply and are configured to open and close the electrical connection between the inner end of the respective cell stack 17, 18 and the terminal of the power supply. Switching element S7 allows the grounding 13 to be electrically connected to the drawbar or anchor 10. The electrically conductive drawbars or anchors 10, 11 are electrically connected to the end plates 8, 9, which in turn are electrically connected to the end plates 70 and thus to the outer ends of the cell stacks 17, 18. They are electrically conductive and, as an electrical conductor 12, connect the corresponding electrical terminals at the outer ends of the cell stacks 17, 18.The pull rod or pull anchor 10 is also electrically connected to the negative terminal of the power supply.

[0107] In the first switching state, the first cell sub-stack 18 is disconnected from the power supply circuit 2 by opening switching elements S1 and S7 and closing switching element S2. The second cell sub-stack 17 continues to be supplied with energy for electrolysis. In a second switching state, analogous to the first switching state, the second cell sub-stack 17 can be disconnected from the circuit by opening switching elements S2 and S7 and closing switching element S1. In an initial state, both cell sub-stacks 17 and 18 can be connected in parallel in the circuit by closing switching elements S1 and S2 and opening switching element S7. Furthermore, in an off state, both cell sub-stacks 17 and 18 can be disconnected from the power supply 2 by opening switching elements S1 and S2.

[0108] In addition to electrolysis devices such as those in the Figures 1 to 4 , in which two cell stacks 5, 6; 17, 18 are connected or switchable either in series or in parallel, electrolysis devices are also possible in which two groups of cell stacks are connected or switchable in series to each other and are electrically isolated from each other by a separator according to the invention, wherein in each of the groups several cell stacks are connected or switchable in parallel to each other and are separated from each other by separators according to the invention.

[0109] In the Figures 5a to 5j The diagrams show schematic (not to scale) embodiments of separators in a side sectional view. The separator bodies are disc-shaped and have contact surfaces 20 on each of their opposite long sides, which allow them to be placed against the surface of electrolysis cells or end plates of cell stacks.

[0110] Separator bodies can be monolithic, i.e., consisting of a single piece, or they can consist of segments. Segments can, in turn, consist of subsegments. Figures 5a to 5f They show monolithic separator bodies. Figures 5g to 5j show examples of segmented separator bodies. The segmentation can be, as in the Figures 5g and 5h As an example, the cell part stacks are arranged perpendicular to their longitudinal axis, and the separator, with its contact surfaces 20, is placed on their surfaces. However, segmentation parallel to the longitudinal axis of the cell part stacks is also possible, as in the Figures 5i, 5j , 7b, 7c, 8 and 9 The segments can touch each other or have a gap or space between them.

[0111] The contact surfaces 20 of a separator can be designed such that they completely cover the surfaces to which they are attached, as in the examples of Figures 5a to 5e, 5g and 6shown, or they can only partially cover them if, for example, they have openings or through-holes, as shown in the Figures 5f and 5h to 5j as well as 7b, 7c, 8 and 9 depicted.

[0112] The openings or through-holes are located between the opposing sides of the separator body, on which the contact surfaces 20 are formed, preferably parallel to the longitudinal axis of the cell stacks against whose surfaces the separator body with its contact surfaces 20 is placed, or to which the contact surfaces 20 are at least partially congruent. Through-holes can, for example, be formed in a monolithic separator body, as in the Figures 5f or 7a shown. Breaks can be columns or spaces between segments, as in the Figures 5i, 5j , 7b, 7c, 8 and 9shown. Perforations or openings that are formed parallel to the longitudinal axis of the cell stacks do not cause any cross-sectional weakening in the separator body in the direction of the clamping force, so that the clamping force is applied particularly advantageously to a solid area of ​​the separator body.

[0113] Figure 6 Figure 1 shows a separator whose separator body 19 has a circular disk shape. This means that the side surfaces of the separator body 19 are each circular and are spaced closer together than their diameter. The circumferential edge 21 of the separator body 19 is correspondingly much shallower than the diameter of the circle, reflecting the circular disk shape. The two side surfaces of the circular disk each form a contact surface 20 against which an electrolysis cell or end plate of a cell stack can be placed.

[0114] In order to be applied to the surfaces of the electrolysis cells or end plates, the contact surfaces 20 of the separator body 19 are designed to be complementary to the surfaces of the electrolysis cells or end plates. Figure 6The contact surfaces 20 are planar and parallel to each other on opposite sides of the separator body 19, so that they can be applied to two mutually parallel surfaces. If mechanical or thermal deformations occur on the surfaces to which the contact surfaces 20 are applied during clamping of the cell component stacks to form the electrolysis cell stack or during electrolysis operation, the contact surfaces 20 can also be designed to counteract these deformations by an excess of material, i.e., by an increased thickness of the separator body 19 in the areas that, in the clamped state and / or during operation, bear against deformed points on the surfaces. The circular disk of the separator body 19 can, for example, have a convex contact surface 20, as shown in Fig. 5b , be lenticular in shape, as in Fig. 5c or 5e , or be wedge-shaped, as in Fig. 5d or 5e, in which the installation surfaces 20 are inclined towards each other at least in sections.

[0115] In Figure 6 The separator body 19 is formed with a circumferential overhang at the edge 21 of the separator body 19. The overhang has a free surface on each of the opposite sides of the separator body 19. The free surfaces are in Figure 6 For simple manufacturing, they are each designed as an extension of the mounting surfaces 20, i.e., they run in the plane of the respective mounting surface 20. However, the free areas can also be offset inwards or outwards with respect to the plane of the mounting surface 20 and / or have recesses or projections.

[0116] Without an overhang, the shortest path along the surface of the edge 21 of the separator body 19 between the contact surfaces 20 of the opposite sides of the separator body 19, i.e., from the contact surface of one side to the contact surface of the other side, corresponds to the thickness of the separator body 19 or the distance between the contact surfaces at the edge 21 of the separator body 19. With the overhang, the length of this path is increased by the length of the paths along the free surfaces. The minimum thickness of the separator body 19 can therefore be less than a minimum creep distance. In particular, it can be smaller by up to an amount by which the length of the shortest path along the surface of the overhang at the edge 21 of the separator body 19 is increased compared to the minimum creep distance.

[0117] When the separator body 19 is installed between the cell stacks during electrolysis with aqueous acidic or alkaline electrolytes, the free surfaces are typically oriented vertically, i.e., parallel to the direction of gravity and perpendicular to the longitudinal direction of the electrolysis cell stack. This results in less dirt accumulating and adhering to these surfaces compared to horizontally oriented surfaces. Accordingly, the minimum creepage distance can be a minimum creepage distance required for low to no contamination. Furthermore, the surface of the separator body 19 can have a low surface roughness at the protrusion and on other surfaces, in particular an average roughness depth Rz of a maximum of 100 µm, preferably a maximum of 50 µm, to prevent contamination and facilitate cleaning.

[0118] In the Figure 6The open areas on the overhang are each formed with a continuous, closed groove. This allows the shortest path along the open areas to be increased by the shortest path along the surface of the groove, i.e., along the groove sides and base. The total length of the open areas can thus be reduced by this path length, saving material.

[0119] Instead of a single groove, multiple grooves or differently shaped, completely closed recesses and / or completely closed projections can also be provided. Recesses or grooves have the advantage over projections that they are particularly easy to manufacture using subtractive manufacturing processes, and that less dirt accumulates on the inner surfaces of the recesses or grooves than on projections or vertical open areas.

[0120] The overhang at the edge 21 of the separator body 19 is at least the length of a maximum manufacturing tolerance of the surface diameters of the electrolysis cells or end plates against which the separator body is placed. In the example of the Figure 6 This is the distance between the groove and the outer circumference of the contact surface of the respective side of the separator body 19. This allows the rotationally symmetrical separator body 19 to be moved and rotated for mounting between the electrolysis cells or end plates of the cell stacks, and thus to be positioned particularly easily.

[0121] Figure 7aFigure 1 shows a separator body 22. The separator body 22 is formed by an annular disk. Unlike the circular disk of the separator 19, the annular disk has a circular recess or through-opening in its center. This leaves only the circumferential, closed ring area, which has a contact surface 23 on each side of the separator body. The mean diameter of the annular disk is dimensioned such that the outer surfaces of the respective electrolysis cells or end plates bear against it. Particularly high compressive forces occur at these outer surfaces due to the clamping by the clamping device. The separator body 22 in the exemplary embodiment of Figure 7a exhibits, like the separator body 19 of the Figure 6 a protrusion at the edge, i.e. at the outer circumference, of the separator body 22.

[0122] The minimum thickness of the separator body 22 can correspond to at least a minimum creep distance. The minimum thickness in the prestressed, i.e., compression-loaded, state must be taken into account, which, due to compression of the separator body by the prestressing, may be slightly smaller than in the unprestressed state. This prevents creep from occurring either on the surface in the circular recess, i.e., on the inner circumference of the annular disk, or on the edge of the separator body 22, i.e., on the outer circumference of the annular disk. The circumferential surfaces, i.e., the surfaces on the inner and outer circumferences, of the separator body 22 are, in the example of the Figure 7aThe surface is formed continuously perpendicular to the contact surfaces 23. However, the circumferential surface on the inner circumference can also be a stepped or chamfered surface, or have at least one circumferentially closed projection and / or at least one circumferentially closed recess or groove. If the shortest path along the surface on the inner circumference is thus extended, the minimum thickness of the separator body 22 can also be less than the minimum creepage distance. Minimum creepage distances for specific operating voltages and tracking current resistance can, for example, be defined in the following examples: Figure 12 can be taken from or determined according to DIN EN 60 664-1 2019-01.

[0123] The separator body 22 can, as in the Figures 6 and 7a as exemplified, they may be monolithic or consist of segments, as in the Figures 7b, 7c, 8 and 9 Segments can in turn be segmented into subsegments, as exemplified in Figs. 8 and 9shown. The subsegments can be positively connected to each other at joining surfaces between the subsegments. They can, for example, be connected as in the Figures 10a to 10e shown, featuring stepped or scarfed joining surfaces and also joining surfaces with an undercut.

[0124] Figure 7b Figure 24 shows separator 24. Its separator body has, in addition to an annular segment 25, a circular disk-shaped segment 26 arranged concentrically to it. A gap remains between segments 25 and 26 in the radial direction to save material. In some embodiments, however, segments 25 and 26 can also be configured to be in contact with each other. They can be positively connected to one another via joining surfaces on their inner and outer circumferences. These joining surfaces can, for example, be similar to subsegments, such as stepped or scarfed surfaces, or joining surfaces with an undercut, as shown in the following. Figures 10a to 10e depicted, exhibit.

[0125] The outer segment 25, which is positioned on the outer surface of the electrolysis cells or end plates, can be made of one or more materials that have higher compressive and flexural strength than the material(s) of the inner segment 26, so that higher compressive forces can be transmitted to the segment 25 during clamping. However, in the event of thermal or mechanical deformation of the surfaces to which the separator body's contact surfaces are applied, the inner segment 26 can also be made of material(s) with a high compressive strength equal to, or even higher than, that of the outer segment 25. The same applies to the flexural strength.

[0126] In the Figure 7bThe circumferential surfaces of segments 25 and 26 are continuously perpendicular to the adjacent contact surfaces. However, the circumferential surfaces can also be stepped or chamfered, or have at least one continuous closed projection and / or at least one continuous closed recess. If the shortest path along the respective circumferential surface is thus extended, the minimum thickness of the separator body or the segments can also be less than the minimum creepage distance. In particular, it can be less than the minimum creepage distance by a maximum of the smallest of the amounts by which the shortest path along the surfaces of a projection at the edge of the separator 24 and the shortest paths along the surfaces of the circumferential surface are increased.

[0127] Figure 7cFigure 27 shows the separator. Its separator body has two concentric, annular-disc-shaped segments 28 and 29 and a centrally arranged, concentric, circular-disc-shaped segment 30. The separator body is rotationally symmetrical about an axis through the geometric centers of gravity of the two rotationally symmetrical contact surfaces formed by the segments 28, 29, and 30 on opposite sides of the separator body. A gap remains between the segments 28, 29, and 30 in the radial direction to save material. In some embodiments, however, the segments 28, 29, and 30 can also be configured to be in contact with each other. They can be positively connected to one another via joining surfaces on their inner and outer circumferences. For example, they can create stepped or scarf joint surfaces, as well as joint surfaces with an undercut, as in the Figures 10a to 10e exhibit.

[0128] The inner circumferential surfaces of segments 28, 29, 30 can be, as in the example of the Figure 7cThe segments 28, 29, 30 may be continuous and perpendicular to the adjacent contact surfaces, or be stepped or chamfered, or have at least one circumferentially closed projection and / or at least one circumferentially closed recess or groove. If the shortest path along the surfaces of the circumferential surfaces between the contact surfaces of the opposite sides of the segments 28, 29, 30 is thus lengthened, the minimum thickness of the segments 28, 29, 30, and thus the minimum thickness of the separator body at the joining surfaces, may also be smaller than the minimum creepage distance. In particular, it may be smaller than the minimum creepage distance by a maximum of the smallest of the amounts by which the shortest path along the surface of the separator projection 27 and the shortest paths along the surfaces of the circumferential surfaces of the segments 28, 29, 30 between the contact surfaces are increased.

[0129] The Figures 8 and 9Figure 1 shows another separator. Its separator body 31 has two annular disk-shaped segments and a central circular disk-shaped segment 30. The segments are as shown in Figure 2. Figure 7c The outer segment is formed, but it is subdivided into subsegments 32. In embodiments, however, more than one segment can be subdivided into subsegments, or a segment other than the outer segment can be subdivided into subsegments.

[0130] Manufacturing subsegments 32 results in less waste compared to manufacturing the entire segment from solid material, thus enabling the separator body 31 to be manufactured in a particularly material-efficient manner. In the exemplary embodiment, the subsegments 32 are Figures 8 and 9 Each is connected to the other via stepped joining surfaces; alternatively, the joining surfaces can also be scarfed. In Figure 9The joining surfaces of the subsegments 32 are designed with an undercut. This undercut allows the subsegments 32 to be positively connected to one another in such a way that the relative movement of the subsegments 32 to each other is blocked in more than one spatial direction. This makes the assembled segment mechanically more stable and easier to handle, position, and align during assembly.

[0131] The outer segment, which can be attached to the electrolysis cells or end plates in an outer area of ​​the surfaces, is made of a material with higher compressive and flexural strength than the inner annular disc segment 29, allowing higher compressive forces to be transmitted to this segment during clamping. The circular disc 30, which can be attached to the electrolysis cells or end plates in the center of the surfaces, also has higher compressive and flexural strength than the inner annular disc segment 29. This counteracts deformations in the center of the surfaces to which the separator body 31 is attached.

[0132] Figure 10aFigure 1 shows a detailed view of subsegments 33 and 34 of a separator body, each featuring stepped joining surfaces 35 and 36. The joining surfaces 35 and 36 are complementary to each other, ensuring they lie flush against each other when the two segments 33 and 34 are joined. As an alternative to stepped joining surfaces 35 and 36, the joining surfaces can also be scarfed. Each stepped joining surface 35 and 36 consists of at least three sub-surfaces. These sub-surfaces are arranged at right angles or at acute or obtuse angles to their adjacent sub-surfaces, with the projections of the sub-surfaces arranged side-by-side without overlap, perpendicular to the planes of the contact surfaces. The non-overlapping projections ensure that the subsegments 33 and 34 can be joined together in a single movement perpendicular to their contact surfaces.In some embodiments, the edges of the sub-surfaces can also be rounded.

[0133] The sub-areas can, for example, be stepped, as in Figure 10a The joining surfaces are shown to be arranged at right angles to each other, or in a sawtooth pattern at an acute or obtuse angle to each other. The stepped joining surfaces 35, 36 increase the shortest path along the surface of the joining surfaces in the joining gap between the contact surfaces compared to joining surfaces that are continuously perpendicular to the contact surfaces, where the shortest path between the contact surfaces corresponds to the minimum distance between the contact surfaces at the joining gap or the minimum thickness d of the segment at the joining gap. For stepped joining surfaces 35, 36, the length of the shortest path along the surfaces of the joining surfaces corresponds to the sum of the widths of the respective sub-surfaces of the joining surfaces. Figure 10aThe length of the shortest path in the joining gap is increased by the width b of the partial surface running parallel to the joining surfaces compared to the shortest path on joining surfaces that are continuously perpendicular to the contact surfaces.

[0134] To prevent creep propagation in the joining gap, the minimum thickness d of subsegments 33, 34 can be equal to or greater than the minimum creep distance. Due to the increased length of the shortest path in the joining gap, the minimum thickness d in the example of Figure 10a However, it may be chosen to be smaller than the minimum creep distance. In particular, it can be smaller than the minimum creep distance by a maximum amount by which the length of the shortest path along the joining surfaces is greater than the minimum creep distance.

[0135] Figure 10bFigure 41 shows a top view of a mounting surface 41, depicting subsegments 37 and 38 of a separator body, which have joining surfaces 39 and 40. Joining surfaces 39 and 40 each have undercuts, allowing them to interlock positively according to the hook-and-loop principle. This enables force transmission across the mounting surfaces, even in the circumferential direction. Consequently, the transmission of tensile forces is possible, and the subsegments 37 and 38, joined to form a single segment, can be easily positioned, aligned, and rotated between the surfaces of the electrolysis cells or end plates for assembly.

[0136] In the Figures 10c, 10d and 10e Subsegments 42, 43 with undercuts at the joining surfaces 44, 45; 47, 48 and 50, 51 are shown. In the example of the Figure 10c The joining surfaces 44, 45 and the circumferential surface 46 of the subsegments 42, 43 are formed in a step-like manner. Figure 10dThe joining surfaces 47, 48 are scarfed and the circumferential surface 49 is chamfered. The circumferential surface 49 is chamfered at the edges adjacent to the contact surfaces of both sides of the subsegments 42, 43; however, it can also be chamfered only at the edge adjacent to one of the contact surfaces, as is the case, for example, with the joining surfaces 47, 48. In the Figure 10e The joining surfaces 50, 51 are stepped and the circumferential surface 52 has a projection. When the subsegments are joined to form an annular disk-shaped segment, this projection extends over all subsegments along the entire inner and outer diameters of the annular disk segment.

[0137] In examples 10c to 10e, the length of the shortest path from contact surface to contact surface increases both in the joining gap along the joining surfaces 44, 45; 47, 48; 50, 51 and along the circumferential surface, i.e., along the surfaces on the outer and inner circumferences 46, 49, 52, compared to the shortest path along joining surfaces or circumferential surfaces that are continuously perpendicular to the contact surfaces. In particular, it can be less than the minimum creepage distance by at most the amount by which the length of the shortest path along the joining surface or circumferential surface is greater than the minimum creepage distance.

[0138] Figure 11aFigure 1 shows a lateral sectional view of two cell stacks 63 and 64, between which a separator body 53 is arranged. The separator body 53 has free areas 54 and 55, which project beyond the contact surfaces against which the outer electrolysis cells or end plates of the cell stacks 63 and 64 rest. The free areas 54 and 55 each have at least one circumferential, closed recess 56 and 57. The recesses 55 and 56 are shown in the example of the Figure 11a The recesses 56 and 57 are formed as grooves with a rectangular cross-section and a base that runs parallel to the open areas 54 and 55. However, the recesses 56 and 57 can also have other cross-sectional shapes. In some embodiments, only one of the recesses 56 or 57 may be provided, or more than one recess 56 or 57 may be provided per open area.

[0139] The recesses 56, 57 each increase the length of the shortest path at the overhang between the two contact surfaces of the separator body 53. Due to their arrangement on lateral surfaces of the separator body 53, which can be oriented parallel to the direction of gravity during electrolysis, no contaminants can fall into the recesses 56, 57 in the direction of gravity, i.e., from above. Such contaminants, if conductive or becoming conductive upon moisture absorption, could cause electrical conduction between the electrolysis cells 63, 64, resulting in leakage currents, which must be avoided.

[0140] The separator body 53 can additionally or instead of the recesses 56, 57 also have at least one circumferential, closed recess 58, 59 on a circumferential surface. These recesses or grooves also prevent the occurrence of leakage currents. They increase the length of the shortest path along the surface of the circumferential surface between the contact surfaces. In the Figure 11a The circumferential surface is a surface on the inner circumference of a segment of the separator body 53. However, a circumferential surface can also be a surface on an inner outer circumference of a segment. "Inner" means that the circumferential surface is not located at the edge or on the overhang of the separator body, but rather between the surfaces of the electrolysis cells or end plates, when the contact surfaces are in contact with these.

[0141] For simplified manufacturing, the recesses 58, 59 can be used as shown in Figure 11aThe recesses 58, 59, as shown, can be arranged on one of the mounting surfaces. This allows the recesses 58, 59, similar to the recesses 56, 57 on the free surfaces, to be manufactured particularly easily using a subtractive manufacturing process. The groove base of the recesses 58, 59 can be parallel to the mounting surfaces. Furthermore, projections can be provided on the circumferential surface in addition to or as an alternative to recesses 58, 59 to prevent creepage currents. In the example of the Figure 11a For example, the area between the recesses 58, 59 can also be referred to as a projection.

[0142] Figure 11bFigure 53 shows a lateral sectional view of two cell stacks 63, 64 between which a separator 53 is arranged. The overhang of the separator body 53 has at least one projection 60, 61 on one or both of its free surfaces. The projections 60, 61 can be present in addition to recesses 56, 57 on the free surfaces. They also increase the protection against creep. A circumferentially closed recess 62 or groove can be provided on a circumferential surface of the segment of the separator body 53. In the example of the Figure 11b The recess 62 is located on an inner circumference of a segment of the separator body, but it can also be provided on an inner outer circumference.

[0143] In Figure 12For electrolysis operation up to 2000 m above sea level and with creepage currents <0.5 A, the minimum creepage distance is shown as a function of the tracking resistance of the separator body material(s), the degree of contamination (VG), and the maximum voltage difference between the ends of the shortest path between the contact surfaces or between the electrolysis cells or voltage-bearing end plates to whose surfaces the separator body is in contact during electrolysis operation. With little to no contamination, the minimum creepage distance is less than 10 mm. The minimum distance between the contact surfaces or the minimum thickness of the separator body can therefore also be less than 10 mm. With heavy contamination and a maximum voltage difference above 1000 V DC, the minimum creepage distance is greater than 10 mm. Reference sign

[0144] 1, 15 Electrolysis device 2 Power supply 3 Positive terminal of the power supply 4 Negative terminal of the power supply 5, 6; 17, 18; 63, 64 Cell stack 7 Electrolysis cells 8, 9 End plates 10, 11 Pull rod / arbor 12 Electrical conductor 13 Grounding 14, 16, 24, 27 Separator 19, 22, 31, 53 Separator body 20, 23, 41 Mounting surface 21 Edge of the separator body 25, 26; 28, 29, 30 Segment 26, 30 Circular disc segments 25, 28, 29 Circular ring disc segments 32, 33, 34, 37, 38, 42, 43 Subsegments 35, 36, 39, 40, 44, 45, 47 Joining surfaces 48, 50, 51 46, 49, 52 Circumferential surfaces 54, 55 Free area 56, 57, 58, 59, 62 Recess 60, 61 Projection 70 End plate 80 Switch 90 Switchable conductor S1-S7 Switching elements

Claims

1. Separator (14, 16, 24, 27) for electrical insulation of electrolysis cells (7) of an electrolysis cell stack with a separator body (19, 22, 31, 53), a. which has two opposite sides on which contact surfaces (20, 23, 41) for electrolysis cells (7) or end plates of cell part stacks (5, 6; 17, 18; 63, 64) are formed, and b. which is formed entirely of an electrically insulating material or in certain areas of different such materials.

2. Separator according to the previous claim, characterized by the fact that the separator body (19, 22, 31, 53) has a disc-like shape.

3. Separator according to any of the preceding claims, characterized by the fact thatthe contact surfaces (20, 23, 41) are at least partially complementary in shape to a surface of an electrolysis cell or end plate of a cell part stack (5, 6; 17, 18; 63, 64) and / or have an excess of material in areas that can be applied to deformed points on the surfaces of an electrolysis cell or end plate of a cell part stack (5, 6; 17, 18; 63, 64).

4. Separator according to the previous claim, characterized by the fact that the mounting surfaces (20, 23, 41) are at least partially planar or convex.

5. Separator according to any of the preceding claims, characterized by the fact that the contact surfaces (20, 23, 41) of the opposite sides of the separator body (19, 22, 31, 53) are parallel to each other or form a lenticular and / or wedge-shaped separator body.

6. Separator according to any of the preceding claims, characterized by the fact thatthe mounting surfaces (20, 23, 41) and / or the separator body (19, 22, 31, 53) are rotationally symmetric.

7. Separator according to any of the preceding claims, characterized by the fact that the separator body (19, 22, 31, 53) consists of at least one material which has a tracking resistance of at least 200 V, preferably at least 400 V, particularly preferably at least 600 V.

8. Separator according to any of the preceding claims, characterized by the fact that the separator body (19, 22, 31, 53) consists of at least one material having a compressive strength of at least 200 N / mm² 2 , preferably of at least 350 N / mm 2 , has and / or a flexural strength of at least 300 N / mm 2 , preferably at least 350 N / mm 2 , exhibits.

9. Separator according to any of the preceding claims, wherein characterized by the fact thatthe separator body (19, 22, 31, 53) consists of at least one material which is a composite material, preferably a fiber composite material, in particular a glass fiber reinforced epoxy resin material.

10. Separator according to any of the preceding claims, characterized by the fact that the separator body (31, 53) is formed from several segments (32; 33, 34, 37, 38, 42, 43), wherein the segments (32; 33, 34, 37, 38, 42, 43) are spaced apart from each other or touch each other.

11. Separator according to one of the two preceding claims, characterized by the fact that the segments are divided into subsegments (32).

12. Separator according to one of claims 10 or 11, characterized by the fact that Each pair of segments or subsegments (33, 34; 37, 38; 42, 43) has complementary joining surfaces (35, 36; 39, 40; 44, 45; 47, 48; 50, 51).

13. Separator according to claim 12, characterized by the fact thatthe joining surfaces are designed in a step-like (35, 36, 44, 45; 50, 51) and / or scarfed (47, 48) form.

14. Separator according to one of claims 12 or 13, characterized by the fact that Projection surfaces of sub-areas of the joining surfaces (35, 36; 44, 45; 47, 48; 50, 51) onto the plane of a mounting surface are arranged side by side without overlap.

15. Separator according to one of claims 12 to 14, characterized by the fact that the joining surfaces (39, 40; 44, 45; 47, 48; 50, 51) each have at least one undercut that allows force transmission between the two respective segments or subsegments.

16. Separator according to any of the preceding claims, characterized by the fact thatthe length of a shortest path along a surface of passages or openings, in particular along joining surfaces, and / or along circumferential surfaces of segments between the contact surfaces of the opposite sides of the separator body (22, 31) is equal to or greater than the minimum creep distance.

17. Separator according to one of the preceding claims characterized by the fact that the surfaces of through-openings or perforations, in particular along joining surfaces, and / or the circumferential surfaces (46, 49, 52) of segments are stepped or chamfered and / or have at least one projection and / or at least one recess (58, 59, 62).

18. Separator according to any of the preceding claims, characterized by the fact thata circumferential line encompassing one of the contact surfaces (20, 23) encloses an area wherein - the area is equal in size to the surface of the electrolysis cell (7) or end plate of a cell part stack (5, 6; 17, 18; 63, 64) to be applied to the contact surface (20, 23), so that the separator body is flush with the surface when the contact surface (20) is applied to the surface, or - the area is larger than the surface of the electrolysis cells (7) or end plate of a cell part stack (5, 6; 17, 18; 63, 64) to be applied to the contact surface (20), so that the separator body (19, 22, 31, 53) has a projection that extends beyond the surface when the contact surface (20, 23, 41) is applied to the surface.

19. Separator according to claim 18, characterized by the fact thatthe separator body (19, 22, 31, 53) has a completely closed overhang and the length of the shortest path along the surface of the overhang between the plant surfaces of the opposite sides corresponds at least to the minimum creep distance.

20. Separator according to claim 19, characterized by the fact that the separator body (19, 22, 31, 53) has at least on one side a free area (54, 55) on the overhang, which is located beyond a circumferential line limiting the mounting surface (20, 23) of the side, on which at least one circumferentially closed recess (56, 57) and / or at least one circumferentially closed projection (60, 61) is present.

21. Separator according to one of claims 19 or 20, characterized by the fact thatthe separator body (19) is monolithic between the contact surfaces and the minimum distance d between the contact surfaces of the opposite sides is less than the minimum creep distance by an amount by which the length of the shortest path along the surfaces of the overhang between the contact surfaces is greater than the minimum creep distance.

22. Separator according to one of claims 19 or 20, characterized by the fact that the separator body (22, 31, 53) has at least one through-opening or perforation, in particular between joining surfaces (35, 36, 39, 40, 44, 45; 47, 48, 50, 51), and the minimum distance d between the contact surfaces of the opposite sides of the separator body is less than the minimum creep distance by at most the smallest of the amounts by which the lengths of the shortest path lengths along the surfaces of the overhang, the through-openings, perforations and circumferential surfaces are greater than the minimum creep distance.

23. Separator according to any one of the preceding claims 20 to 22, characterized by the fact that the open area (54, 55) has at least one circumferentially closed recess (56, 57) and the minimum creep distance is a minimum creep distance for low or no contamination.

24. Electrolysis cell stack comprising at least two cell sub-stacks (5, 6; 17, 18; 63, 64) between which a separator (14, 16, 24, 27) is arranged according to one of the preceding claims.

25. Electrolysis cell stack according to claim 26, characterized by the fact that the arrangement of cell part stacks (5, 6; 17, 18; 63, 63) and separator (14, 16, 24, 27,) is clamped by a common clamping device (8, 9, 10, 11).

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