Leakage proof and assembly optimized electrolysis cell and electrolysis cell stack

Abstract

This invention concerns an electrolysis cell comprising an anode compartment with an anode in contact with an anode support, a cathode compartment with a cathode in contact with a cathode support, a separator between the anode and the cathode compartment and a sealing member for sealing an electrolyte in the anode and the cathode compartment, wherein the sealing member comprises a polymer blend of at least two different polymers A and B, wherein the polymer A is selected from the group consisting of polymers according to the following formula 1, (1) wherein n = 10 – 20.000, m = 0, 1 or 2, each R1 is independently selected from the group consisting of C1-C3-Alkyl or a further polymer chain according to formula 1, X is independently selected from the group consisting of S, O, SO2, CH2, CO, or isomeric forms or mixtures thereof; and polymer B is selected from the group consisting of synthetic elastomeric rubbers or mixtures thereof. Furthermore, the invention is directed to an electrolyser stack comprising two or more of the inventive electrolysis cells.

Description

[0001] Leakage proof and assembly optimized electrolysis cell and electrolysis cell stack

[0002] The invention relates to an electrolysis cell comprising an anode compartment with an anode in contact to an anode support, a cathode compartment with a cathode in contact to a cathode support, a separator between the anode and the cathode compartment and a sealing member for sealing an electrolyte in the anode and the cathode compartment, wherein the sealing member comprises a polymer blend of at least two different polymers A and B, wherein the polymer A is selected from the group consisting of polymers according to the following formula 1 , formula 1, and polymer B is selected from the group consisting of synthetic elastomeric rubbers or mixtures thereof. Furthermore, the invention is directed to an electrolyser stack comprising two or more of the inventive electrolysis cells.

[0003] Hydrogen is a versatile molecule and widely used in industrial processes, e.g. in chemical synthesis, in metal processing or petroleum refining. Besides fulfilling the task of a chemical reaction partner, nowadays the role of hydrogen as a “green” energy storage mean has become highly important, because hydrogen is principally able to offer an environmentally friendly alternative to the use of hydrocarbon-based energy molecules. In the energy storage cycle electrical energy can be converted to chemically stable hydrogen molecules or electrical energy can be generated by the controlled breakdown of said molecules. The latter process is for instance performed in fuel cells, wherein the first process is performed on an industrial scale in single electrolysis cells or in electrolysis cell stacks, wherein in the latter form several electrolysis cells are physically connected. The fundamental set-up of electrolysis cells and electrolysis cell stacks is known for decades, nevertheless, the high importance to shift a major part of the energy system to green solutions and the increasing demand for hydrogen in new applications still drives the optimization of the cell design, in order to achieve higher electric efficiencies in the electrolytic conversion and an easier cell assembly and maintenance including a longer cell service life. In this aspect special attention has to be drawn to the mechanical sealing of the individual electrolytic cell, because the sealing of each cell compartment with respect to the cell outside is one of the weakest spots in cell design and a pre-requisite for a save and long term stable electrolytic process.

[0004] The different strategies in sealing of electrolysis cells and electrolysis cell-stacks are also discussed in the patent literature.

[0005] EP 0 402 909 Al, for instance, discloses a gasket for sealing adjacent flat members of an electrolytic cell, at least one of the flat members being a cell separator and the other being a cell frame member, or a liner for the cell frame member, the gasket comprising a one-piece laminated structure of a picture frame configuration, having at least two layers of a polymeric sealing material, or an elastomeric sealing material, and a reinforcing scrim material interposed therebetween, and a plurality of pointed pegs or pins projecting in a direction generally normal from the gasket structure for mating with holes in the cell frame member or the cell frame liner.

[0006] US 10 749 153 A describes a sealant for an electrochemical device in which a non-aqueous electrolysis solution is used, comprising: a conjugated diene polymer (A); an aromatic vinyl- conjugated diene block polymer (B); and a hydrogenated amine-modified aromatic vinyl-conjugated diene block polymer (C).

[0007] Furthermore, GB837865A discloses an electrolyser of the filter press form of construction, in which the disc shaped cells arranged in series in a pack are each subdivided by a diaphragm the edge whereof is gripped between adjacent cell frames which are themselves in contact with either of two electrodes and reciprocally insulated electrically by means of a packing or gasket, characterized in that the insulating packing or gasket consists of a deformable core which is wrapped with a foil or film of poly-fluoro-ethylene. EP 2 872 675 Bl discloses an electrolysis cell, comprising an anode compartment shell and a cathode compartment shell, which are physically separated by a membrane and equipped with an insulating frame, the insulating frame being arranged between anode compartment shell and the membrane, said insulating frame having a geometric form with comers and being of a flat design and having an anode and a cathode side as well as an outer and inner end face, the insulating frame being characterised in that it has an edge area directly adjoining the inner end face, characterised in that the edge area has corner expansion joints in the form of material cutouts arranged so as to face away from the membrane in the installed condition designed so as to compensate linear expansion of the insulating frame, wherein one of the comer expansion joints is located directly in each corner of the edge area and at a pointed angle to the outer end face of the insulating frame.

[0008] Such solutions, known from the prior art, may offer further potential for improvement, especially regarding the ease of assembly and the operational safety of the electrolysis cells even at high pressures and temperatures.

[0009] It is therefore the task of the present invention to at least partially overcome the disadvantages known from the prior art. In particular, it is the task of the present invention to disclose an electrolysis cell design with an improved sealing of the cell compartments. Furthermore, it is the task of the present invention to provide electrolyser cell stacks based on the inventive cells which are easily up-scalable, simple to manufacture and maintain, less prone to leakages and with good corrosion resistance for a long service life.

[0010] The task is solved by the features of the independent claims, directed to the electrolysis cell according to the invention and the electrolysis cell stack according to the invention. Preferred embodiments of the invention are described in the dependent claims, in the description or in the figures, whereby further features described or shown in the dependent claims or in the description or in the figures may individually or in any combination constitute an object of the invention if the context does not clearly indicate the contrary.

[0011] According to the invention the problem is solved by an electrolysis cell comprising an anode compartment with an anode in contact with an anode support, a cathode compartment with a cathode in contact with a cathode support, a separator between the anode and the cathode compartment and a sealing member for sealing an electrolyte in the anode and the cathode compartment, wherein the sealing member comprises a polymer blend of at least two different polymers A and B, wherein the polymer A is selected from the group consisting of polymers according to the following formula 1 5formula 1, wherein n = 10 - 20.000, m = 0, 1 or 2, each R1is independently selected from the group consisting of Cl-C3-Alkyl or a further polymer chain according to formula 1, X is independently selected from the group consisting of S, O, SO2, CH2, CO, or isomeric forms or mixtures thereof and polymer B is selected from the group consisting of synthetic elastomeric rubbers or mixtures thereof, wherein the weight ratio of the polymers A and B in the blend, calculated as the weight of polymer A divided by the weight of polymer B, is larger than or equal to 1 and smaller than or equal to 20 and the weight contribution of polymer A and B in the polymer blend is larger than 70.0 weight-%.

[0012] Surprisingly it has been found that the electrolysis cell according to the invention, and here especially the sealing member material, combines several advantages with respect to the known sealing members of the prior art. The sealing member provides corrosion resistance against harsh process media utilized in a wide range of different electrolysis processes with the elasticity required to create a reliable seal. These benefits can be optioned even at high temperatures and high internal cell pressures. The sealing member minimizes assembly efforts, because the sealing member can be moulded at reasonable costs into a single piece with a shape preferred for easy assembly such as one including clips or mushroom heads for simple fastening and / or, if required, be moulded onto or around other components such as bipolar plates (BPP), frames, or diaphragms. An extensive manual handling during stack / cell assembly can thus be avoided. In addition, the sealing member prepared from such polymer blend features a very good corrosion resistance, which significantly prolongs the service life of the electrolysis cell when compared to standard EPDM sealing members as polymers like polyphenylene sulphide or polysulfone polymer provides protection for the elastomeric polymers like EPDM against chemical attack. Service life of 5-10 years can easily be achieved. The sealing members according to the invention show an improved elasticity & resilience, wherein the polymer blend exhibits an elasticity approaching that of hard elastomers and can thus be used as sealing members with good sealing properties.

[0013] Such behavior of a sealing member in the surrounding of an electrolysis cell is advantageous compared to standardly used material like EPDM gaskets. Sealing members made from EPDM alone are a well-known and widely used gasket material for various applications throughout the industry. The production process typically involves e.g. injection molding of the uncured EPDM into the required shape, followed by a curing step, also possible by ’’cure in place“ processes. This freedom in design makes application straightforward and EPDM gaskets require relatively small gasket stress / compression force to achieve high tightness with common flange designs like raised face or flat face. Nevertheless, EPDM suffers from long-term corrosive attack, especially under hot caustic and oxidizing conditions, limiting its lifetime and increasing the risk of leaks. It is not expected to match the service lifetime of other components of the electrolysis cell such as the separator or diaphragm and thus increases the amount of required service & maintenance cycles when compared to gaskets with longer service life-times.

[0014] Besides pure EPDM-sealing members, expanded strips made from PTFE can also be used. Expanded PTFE (ePTFE) is produced by extruding and stretching pure PTFE resin. It is well- known for its excellent corrosion stability. Unlike EPDM, however, the material has to be cut from sheet material or used as sealing cord in a more labor-intensive application process, involving cutting and layering. Expanded PTFE is known to require a higher amount of seal stress to create a tight seal, being significantly higher than EPDM gaskets, yet may unfavourably exhibit gas diffusion rates exceeding those of EPDM or other gaskets. It also needs to be used in sufficient thickness or in combination with an isolation frame to provide sufficient electric isolation, increasing its material cost, but suffers from its lack of elasticity / high compression set. ePTFE does not exhibit significant flexibility. During creation of a seal, it irreversible deforms and, as a result, the seal cannot be reused after opening of the cell (e.g. for inspection or maintenance), and a new seal needs to be used. ePTFE strips also comprise a tendency to creep under pressure, necessitating more complex flange face designs like tongue and groove. They require much higher forces to achieve tightness. In addition, a potential EU ban on PF AS materials could affect its future availability.

[0015] The electrolysis cell according to the invention can, for instance, be a water electrolysis cell or a chlor-alkali (CA) cell. A water electrolysis cell is able to generate oxygen and hydrogen from water, and a CA cell is able to generate chlorine from aqueous halide salt solutions by the application of a DC electrical power. The water electrolyser can be of the PEM-(Polymer Electrolyte Membrane), AEM (Anion Exchange Membrane) or the alkaline-type. PEM and AEM electrolysers are able to process pure water as the electrolyte. The electrodes for the PEM-type are made from noble metals, and the separator is a proton-conducting membrane usually made from a perfluorinated sulfonic acid polymer. The electrodes for the AEM type are made from non-noble metals, and the separator is a hydroxide-conducting membrane. Preferably the water electrolysis cell is a cell for alkaline electrolysers or AWEs. AWEs preferably use aqueous KOH solutions. The chemistry of the reaction allows the use of cheap non-noble electrodes, e.g. based on nickel. The Chlor-alkaline electrolyser cell (CA) can be of the NaCl- or KCl-type, using respective salt solutions. It can also be of the HCl-type, using aqueous hydrochloric acid as electrolyte. Preferably, the electrolysis cell is an AWE or CA cell.

[0016] The electrolysis cell comprises an anode compartment with an anode in contact with an anode support and a cathode compartment with a cathode in contact with a cathode support. In the anode compartment in the case of an AWE cell the oxidation of the hydroxide ions in the electrolyte to oxygen and water is performed. The reaction takes place at the anode electrode, which is either directly or indirectly connected to the DC power source. The electrode is in electrical contact to an electrically conducting support, wherein in case of a combination of several cells to a stack the support is called a bipolar plate, because electrodes are present on both sides of the support. At both ends of the stack the cells comprise an end plate. In the case of a single cell, only one electrode, the anode, is present at the anode support and attached or fixed at one or more positions to the support. The anode electrode can for instance be a nickel-electrode. The anode compartment is filled during the reaction with the alkaline aqueous electrolyte. The reaction products e.g. electrolyte (or anolyte) and oxygen leave, at least in part, the anode compartment. In the cathode compartment of e.g. an AWE the reduction of the water in the electrolyte to hydrogen and hydroxide ions is performed. The reaction takes place at the cathode electrode, which is either directly or indirectly connected to the DC power source. The cathode is in electrical contact to an electrically conducting support, wherein in case of a combination of several cells to a stack the support is called a bipolar plate, because electrodes are present on both sides of the support. In the case of a single cell, only one electrode, the cathode, is present at the cathode support and attached or fixed at one or more positions to the support. The cathode electrode can for instance be a nickel-electrode. The cathode compartment is filled during the reaction with the electrolyte. The reaction products hydrogen and electrolyte (catholyte) leave, at least in part, the cathode compartment.

[0017] The electrolysis cell comprises a separator between the anode and the cathode compartment.

[0018] The anode and the cathode compartments are physically separated by a separator, wherein the separator is a porous diaphragm (in the case of AWE) or is an ion-selective membrane (in the case of PEM, AEM and CA) allowing electrolyte and / or ions, respectively, to pass from the anode to the cathode side or vice versa. At the same time the separator prohibits a cross-over flow of reaction gases like oxygen and hydrogen between the anode and the cathode compartment.

[0019] A sealing member for sealing an electrolyte in the anode and the cathode compartment is present in the electrolysis cell. The sealing member can for instance be arranged between the electrically conducting anode support and the electrically conducting cathode support. The sealing member can be configured for sealing the electrolyte in the anode compartment and the electrolyte in the cathode compartment. The anode and the cathode compartment combined can form together with the separator an electrolysis cell volume. This cell volume is separated with respect to the cell surrounding by the sealing member, e.g. in the form of a gasket. The sealing member is electrically isolating the anode and the cathode in the cell. The sealing member can be a single- or a multi-part item. The sealing member may be formed by a gasket between the bipolar plates, by a frame and a gasket between the bipolar plates, or by a frame around at least one support or bipolar plate with gaskets in between. The seal or the gasket is a polymeric seal or gasket and the seal is in direct or indirect physical contact with the supports or, in case of a stack, the bipolar plates. The sealing member can be arranged in between the supports and prevents any leakage of electrolyte or gas from the cell volume to the surrounding. Preferably, the seal or gasket is arranged at the outer circumference of the support, e.g. 0,5 cm to 2 cm away from the outer circumference of the support or flush with the outer circumference or protruding beyond the outer circumference. This seal forms as such or as a part of a more sophisticated combination of a frame and a gasket the pressure bearing part or, e.g. further in combination with a pressure ring, e.g. a metallic hoop, part of the pressure bearing part of the cell in case that the inner cell volume and the outer surrounding of the cell comprise a pressure difference. Usually, AWEs for instance are performed at an operating pressure higher than standard pressure, i.e. the hydrogen and / or oxygen has a gas pressure higher than ambient. Therefore, the sealing member has at least to withstand this inner cell to surrounding pressure difference during operation.

[0020] The sealing member comprises a polymer blend of at least two different polymers A and B. The sealing member comprises at least two different polymers, wherein the distribution of the two polymers throughout the sealing member is homogeneous on the pm to mm scale. The term blend describes that the sealing member can for instance be formed by blending or mixing the two polymers, e.g. in a dry particular form, or in a liquid state or dispersed, followed by forming the sealing member, e.g. by heat and / or pressure treatment of the polymer mixture. The heat and / or pressure treatment establishes covalent or van-der-Waals interactions between the different polymer species and forms a coherent polymer blend, wherein one polymer is for instance embedded in a micro-meter or sub-micro-meter particular form in a continuum of the other polymer. The term blend especially excludes an inhomogeneous distribution of the polymer A and B throughout the sealing member, e.g. in the form of separate polymer layers, an inner core made of one of the polymers and a surrounding made from the other polymer or the distribution of macroscopic polymer particles within the other polymer, such as reinforcing fibers of one polymer in the other polymer. A polymer blend can for instance be assumed in cases, wherein on a cubic-millimetre scale throughout the sealing member the same concentration of polymer A and B is present. The use of a polymer blend especially assures that the sealing member comprises homogeneous stability, elasticity, and resistance to chemical degradation. Such homogeneous properties are not achievable by an inhomogeneous distribution of one polymer in the other polymer.

[0021] Polymer A can form a continuous phase and polymer B can form a disperse phase within the continuous phase of polymer A. Polymer B can be mostly or fully encapsulated by the continuous phase of polymer A. The disperse phase can be formed by polymer B only or by polymer B and other polymers C, D, etc. For example, the disperse phase can be formed by polymer B, polymers B and C, polymers B and D, polymers B, C and D, etc.

[0022] Polymers C, D, etc. can be selected from the same group as polymer B, i.e. synthetic elastomeric rubbers or mixtures thereof, or from other groups.

[0023] Each polymer B, C, D, etc. can form a disperse phase within the continuous phase of polymer A. Additionally, or alternatively, there may be a disperse phase of one or more additional polymers C, D, etc. within the disperse phase of another polymer. Such a dispersion structure is also referred to as a sea / island / lake structure. For example, polymer B can form a disperse phase within the continuous phase of polymer A and polymer C can form a disperse phase within the disperse phase of polymer B.

[0024] The continuous and disperse phases can be identified in the morphology of the sealing member when observed with a transmission electron microscope.

[0025] The number average particle size of the disperse phase formed at least by polymer B is preferably 1000 nm or less, and more preferably 700 nm or less in order to exhibit excellent toughness and flexibility. The lower limit of the number average disperse particle size of the disperse phase is preferably 5 nm or more.

[0026] The number average particle size of the disperse phase can be identified as follows. For example, an ultrathin section is cut out using an ultramicrotome, and a sample obtained by staining the ultrathin section with ruthenium tetroxide or the like and an unstained sample are observed with a transmission electron microscope at a magnification of 5000 to 10000 times. From the obtained image, 10 random different disperse phases are selected, the major diameter and the minor diameter of each disperse phase are determined to take average values, and the number average value of these average values can be calculated as the number average disperse particle size of the disperse phase. The identification of the components constituting the disperse phase can be determined by comparing a phase contrast difference in an unstained sample with a phase contrast difference in a sample stained with ruthenium tetroxide or the like.

[0027] The polymer A is selected from the group consisting of polymers according to the following formula 1 wherein n = 10 - 20.000, m = 0, 1 or 2, each R1is independently selected from the group consisting of Cl-C3-Alkyl or a further polymer chain according to formula 1, X is independently selected from the group consisting of S, O, SO2, CH2, CO, or isomeric forms or mixtures thereof. The polymer can be a “simple” polymer just comprising sulfur-heteroatoms. Nevertheless, also polymers are possible comprising besides sulfur also sulfur oxides, alkylenes, oxygen, or CO-bridging groups in the polymeric chain. Mixtures of different X may be present, e.g. in the form of SO2- and -O- bridging units in the polymer. The side groups R1may be present at different positions at the aromatic ring. In case that more than one side group R1is present the R1can be the same but do not have to be the same. The side group R1can also be formed by covalently crosslinking another polymer to that unit. In the latter case a branching of the polymer is generated. Isomeric variants of the monomeric unit encompass the attachment of the bridging group at different positions of the aromatic ring structure. Mixtures of the polymer A may include polymeric chains according to the above depicted Markush formulae, but different chemical compositions.

[0028] One member of the polymer A group may be a polyphenylene sulfide, wherein the polyphenylene sulfide comprises repeating units according to the following formula:

[0029] The index n in this case can for instance be in the range from 100 - 40.000. R1can be selected from the group consisting of hydrogen or C1-C3 alkyl. The aromatic ring may comprise 1 or 2 R1, wherein the R1can independently be selected from that group. This polymer can further be branched, wherein at least one monomer comprises more than one linkage to other polymers, e.g.

[0030] In this case single linear polymer chains comprises cross-links.

[0031] Other structures according to formula 1 may further comprise partial oxidation products of the polysulfide, wherein a non-aromatic carbon atom or the sulphur is further oxidized or a linkage between different monomers is established by an -O- moiety. Possible derivatives may include:

[0032] Oxidized groups represented by SO2 or CO in the chain may be evenly distributed as indicated by the Markus formulae. In addition, it is also possible that the oxidized groups are randomly distributed throughout the polymeric chain. In this case only some of the groups in the chain are oxidized. Without being bound by the theory, it is believed that the polymer A adds chemical resistance to the polymer. The polymer can be used as a blend of several of the above depicted structures. The polymer A can be incorporated into the polymer blend as a powder, followed by a thermal and / or mechanical treatment.

[0033] The polymer B is selected from the group consisting of synthetic elastomeric rubbers or mixtures thereof. The second component of the polymer blend is a synthetic elastomeric rubber. This means, that the rubber is made from monomers under controlled chemical conditions. The term elastomeric means, that the rubber as such comprises an elastic modulus of larger or equal to 1 MPa and smaller or equal to 50 MPa. The elastomeric rubber can, for instance, be selected from the group consisting of ethylene-propylene-diene monomer (EPDM) rubber, EPDM rubber derivatives, fluoro-elastomer rubbers, FKM (a family of fluorocarbon-based fluoro-elasto- mer materials), NBR (Nitrile rubber, also known as nitrile butadiene rubber), Viton / FKM or SBR (styrene-butadiene rubber). Especially preferred are EPDM rubbers, wherein these rubbers are copolymers of three different monomers, i.e. a ethylene, a propylene and a non-conjugated diene monomer. The diene monomer enables vulcanization of the monomers into a polymeric rubber. The vulcanization can be performed by a cross-liking with sulphur, peroxides, phenolic resins or via radiation curing. Possible non-conjugated dienes may be selected from the group consisting of 2-ethylidene-5-norbornene (ENB), dicyclopentadiene (DCPD), 2-vinyl-5-nor- bomene (VNB), 1,4-hexadiene (HD) and 2-methylidene-5-norbornene (MNB) or mixtures thereof. Possible EPDM rubber derivatives are selected from the group consisting of partially fluorinated EPDM-rubbers, epoxidized EPDM or EPDM functionalised by other functional groups such as carboxylic groups. Especially preferred are epoxidized EPDM rubbers, wherein the polymers of group B may or may not comprise epoxidation. All the other rubbers in the above defined list may also the further functional moieties as defined for the EPDM rubber.

[0034] The weight ratio of the polymers A and B in the blend, calculated as the weight of polymer A divided by the weight of polymer B, is larger than or equal to 0.3 and smaller than or equal to 5. The polymeric components in the blend have to be present in a certain weight ratio in order to provide the necessary elasticity and the chemical resistance of the resulting polymer and the resulting sealing member. The polymer A and the polymer B are used in maximum weight ratio of a 4: 1, wherein the polymer B is present in a lower quantity, compared to the polymer A. In this case the ratio is larger than 1. The polymer B may also be present in a higher quantity, compared to the polymer A. In this case, the ratio is smaller than 1. For the calculation of this polymer-ratio only the weights of the polymer A and the polymer B are counted. The quantitative weight contribution of the single components in the polymer blend can for instance be calculated via a NIR-calibration method. Preferably, this ratio can be larger than or equal to 0.5 and smaller than or equal to 2.

[0035] The weight contribution of polymer A and B in the polymer blend is larger than 70.0 weight- %. The polymers in the group A and B comprise at least 80 weight-% of all polymers in the polymer blend. This means, that the blend is mainly made from polymer A and polymer B. Other polymers, if present, just form minor components in this blend. In this ratio the weight of non-polymeric re-enforcements, like metals or glass-fibres, are not accounted.

[0036] Without being bound by the theory, it seems also to be possible, to slightly alter the group of polymer A and to achieve, within the limitations of the disclosed invention, also a favourable electrolysis cell. In this case, a similar class of aromatic ether-sulfons seems to be able to achieve similar mechanical and chemical properties in the context of an electrolysis cell. Such monomers, similar to those monomeric units forming the polymers in group A, comprise a sulfur-dioxide moiety, ether-linkages and aromatic-rings in the monomer and, consequently, in the polymer chain. Nevertheless, the monomer structure is slightly different compared to the structure displayed by formula 1. An electrolysis cell comprises an anode compartment with an anode in contact with an anode support, a cathode compartment with a cathode in contact with a cathode support, a separator between the anode and the cathode compartment and a sealing member for sealing an electrolyte in the anode and the cathode compartment, wherein the sealing member comprises a polymer blend of at least two different polymers A and B, wherein the polymer A is selected from the group consisting of polymers according to the following formula 2 formula 2, wherein n = 10 - 20.000, m = 0, 1 or 2, each R1is independently selected from the group con- sisting of Cl-C3-Alkyl or a further polymer chain according to formula 2, Z is selected from the group consisting of nothing, -SO2-, -C(CH3)2- or isomeric forms or mixtures thereof and polymer B is selected from the group consisting of synthetic elastomeric rubbers or mixtures thereof, wherein the weight ratio of the polymers A and B in the blend, calculated as the weight of polymer A divided by the weight of polymer B, is larger than or equal to 1 and smaller than or equal to 20 and the weight contribution of polymer A and B in the polymer blend is larger than 70.0 weight-%. By integration of the Z-moieties into chemical formula 2 inter alia the following monomeric unit and polymers derived therefrom are achievable: polyethersulfone (PESU, PES, poly(oxy-l,4-phenylsulfonyl-l,4-phenyl), polyphenylenesulfone (PPSU) polysulfone (PSU, poly(oxy-l,4-phenylensulfonyl-l,4-phenylenoxy-l,4-phenylenisopropy- liden- 1 ,4-phenylen)

[0037] It was found that also polymers from this group of monomers result, within the limitation of the invention at hand, in suitable electrolytic cells. Furthermore, it is also possible to assume that the preferred embodiments disclosed for polymers A derived from formula 1 are workable considering polymers in the group A and polymer blends based on such monomers derived from formula 2, or mixtures of polymer A as derived from monomers according to formula 1 and / or 2.

[0038] In a preferred embodiment of the electrolysis cell the polymer A is polyphenylene sulfide (PPS). Highly resistant but elastic sealing members can be achieved in cases, wherein polymer A is a PPS. The PPS-polymer is a polymer as defined above but may also include the branched PPS- polymers and the oxidized PPS-polymers as outlined above. Preferably, polymer B can be an EPDM-rubber or an EPDM-rubber derivative in this case.

[0039] In a further preferred embodiment of the electrolysis cell, the weight ratio of the polymers A and B in the blend is larger than or equal to 3 and smaller than or equal to 10. For long term stable sealing members, which are able withstanding also the attack of corrosive electrolytes and gases at harsh reaction conditions, it has been found suitable to form the polymer blend in above defined weight ratios. In this case the major component of the blend is polymer A, wherein the polymer B is present at a lower weight. Surprisingly, the corrosion resistance and elasticity is very high at this ratio, resulting in an easy, error forgiving assembly of the cells or the cell stacks at improved leakage rates. In addition, in the case of a maintenance of the cell, the sealing member can be re-used. Within a further aspect of the electrolysis cell the polymer blend comprises a filler material in a concentration of larger than or equal to 0.5 weight-% and smaller than or equal to 20 weight- %, wherein the filler material is selected from the group consisting of ZrCE, BaSCU, TiCE, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, Zirconium hydroxide, Barium hydroxide, titanium hydroxide, potassium titanate, wollastonite, ceramic whiskers, aramid-, PPS-, PSU-, PES-, PPSU-, glass-, alumina-, silicon-, carbide-, ceramic-, metal- or carbon-fibers, or mixtures of at least two members of that list. Besides the selection and the weight contribution of polymers in the group A and B it is also possible to tailor the mechanical properties of the sealing member by integration of filler material. The filler material may be integrated in the polymer blend and may help to further enhance the mechanical stability of the sealing member. The weight contribution of the filler material is given with respect to the overall weight of the sealing member.

[0040] In another characteristics of the electrolysis cell the polymer blend comprises polymer A in a concentration of larger than or equal to 50.0 weight-% and smaller than or equal to 95.0 weight- % and polymer B in a concentration of larger than or equal to 5.0 weight-% and smaller than or equal to 50.0 weight-%, wherein the weight-% are calculated with respect to the sum of the polymeric components of the blend. For sealing members especially in an AWE electrolysis, it has been found suitable to use polymer blends comprising mainly polymer A, e.g. in the form of PPS, and to use polymer B with a lower weight contribution. This weight ratio between the polymers results in very elastic, but resistant sealing members. The sealing members can withstand longer contact times with alkaline solutions and the overall cell can be operated at higher temperatures and pressures. Preferably, the polymer blend comprises polymer A in a concentration of larger than or equal to 52.0 weight-% and smaller than or equal to 75.0 weight-% and polymer B in a concentration of larger than or equal to 23.0 weight-% and smaller than or equal to 45.0 weight-%. Further preferred, the polymer blend comprises polymer A in a concentration of larger than or equal to 55.0 weight-% and smaller than or equal to 69.0 weight-% and polymer B in a concentration of larger than or equal to 29.0 weight-% and smaller than or equal to 42.0 weight-%.

[0041] In another preferred characteristics of the electrolysis cell the sealing member comprises an elastic modulus, measured according to DIN EN ISO 527-1 :2019, of larger than or equal to 0.2 GPa and smaller than or equal to 2.0 GPa. Based on the use of the specific polymeric blend, very chemically resistant sealing members can be achieved, wherein the chemical resistance is only minimally influencing the good elastic properties of the sealing member. The achievable elastic modulus is sufficient to seal also very difficult to seal geometries in the electrolytic cell, e.g. in the case of rough surfaces or edges in or on the surfaces to seal. The sealing member is easily adjustable during assembly and in the course of a maintenance, the sealing member can be temporarily removed and replaced into the same spot. Furthermore, within this modulus range, larger pressure difference occurring during electrolysis can be equilibrated throughout the cell structure and the mechanical forces to assemble electrolysis cell stacks can be kept low. Further preferred, the elastic modulus can be larger than or equal to 0.5 GPa and smaller than or equal to 1.4 GPa, furthermore preferred, larger than or equal to 0.75 GPa and smaller than or equal to 1.3 GPa.

[0042] Within a referred aspect of the electrolysis cell the sealing member comprises a tensile strength, measured according to DIN EN ISO 527-1 :2019, of larger than or equal to 20 MPa and smaller than or equal to 45 MPa. The inventive sealing member comprises an exceptional resistance with respect to the electrolyte and the reaction gases, nevertheless, this chemical robustness does not influence the mechanical properties of the sealing member. Very high tensile strength can be achieved, even without the integration of reinforcing fibers or particles. Lower tensile strength can be disadvantageous, because the needed mechanical long-term stability is not achieved and there is a probability of mechanical failure of the sealing member. Higher tensile strength may be disadvantageous because the sealing member may be too stiff. In another preferred characteristics of the electrolysis cell, the sealing member comprises a sealing member main body and one or more sealing lips extending from the sealing member main body, wherein the cross-sectional area of the sealing member main body is larger than or equal to 15 mm2and smaller than or equal to 500 mm2. Based on the elasticity and chemical resistance, it has been found useful to establish a sealing member in the form of a three-dimensional body instead of a two-dimensional film. The three-dimensional body exhibits a sealing member main body comprising the major weight of the sealing member. The sealing member main body can be defined as the structural part of the sealing member comprising the smallest surface area with respect to the volume of that structural part. The sealing member main body can for instance be present in the form of a closed ring structure, wherein from the ring structure protrusions extend. In this case the main body is the ring structure, wherein the protrusions do not belong to the sealing member main body. Smaller cross-sectional areas of the sealing member main body can be disadvantageous, because the sealing member main body may be too small to achieve a sufficient mechanically stable seal. Larger sealing member main bodies may be disadvantageous, because the necessary mechanic forces to squeeze the sealing member in place may be too high. Examples of the definition of the sealing member main body are given below in the figure description. In case that the cross-sectional area of the sealing member main body varies along the sealing member main body, an average cross-sectional area of the sealing member main body is calculated. Preferably, the cross-sectional area of the sealing member main body is larger than or equal to 30 mm2and smaller than or equal to 400 mm2, further preferred, the cross-sectional area of the sealing member main body is larger than or equal to 50 mm2and smaller than or equal to 300 mm2.

[0043] Within a preferred embodiment of the electrolysis cell, the sealing lips are arranged only on one surface of the sealing member main body. For a proper sealing of the electrolysis cell, it has been found suitable that sealing lips are present on one surface side of the sealing member main body, only. The arrangement of the sealing lips on the main body result in a sealing situation, wherein the sealing lips just contact one surface of the electrolysis cell. The other surface contacted by the sealing member is not in contact with a sealing lip. In case that the sealing member is arranged between two bipolar plates, just one of the bipolar plates is in contact with the sealing lips, wherein the other bipolar plate is in contact with the sealing member main body, only. Such a design of a sealing member may increase the overall flexibility of the sealing member and may result in a more stable sealing situation compared to sealing member comprising sealing lips on both sides of the sealing member main body.

[0044] In a preferred embodiment of the electrolysis cell the sealing lips comprise a cross-section selected from the group consisting of trapezoidal, convex, rectangular or triangular and the cross- sectional area of the sealing lips is larger than or equal to 0.5 mm2and smaller than or equal to 5 mm2. Especially in cases, wherein the sealing member is intended to seal the electrolysis cell between the bipolar plates such configuration of the sealing lips is favorable. Based on the elasticity of the sealing member, relatively small sealing lips are sufficient to seal the overall cell volume. The mechanical pressure on the sealing member is reduced and the lifetime, even under harsh environmental conditions, is prolonged.

[0045] In another preferred aspect of the electrolysis cell, the sealing member main body comprises a recess, wherein the recess is configured to mechanically fix a part of the separator to the sealing member main body. Besides the sealing of the electrolysis cell, the mechanical properties of the sealing member enable the integration of further functions. One possibility is the mechanical fixing of the separator within the cell. The interaction with the separator is established by a recess within the sealing member main body, wherein the separator extends into the recess. This set-up enables an easy assembly of the electrolysis cell or cell stacks and prevents unintended movements of the separator in the cell, even in case of fluctuating pressure or temperature conditions. The mechanical interaction is established by the recess walls in the sealing member main body, wherein the wall is in close surface contact to the separator. The separator is clamped between the recess walls of the sealing member main body in case that a mechanical force is acting on the sealing member. The overall elasticity range of the sealing member enablers a tight clamping of the separator, without risking a mechanical damage of the separator.

[0046] In another embodiment of the electrolysis cell one or more recess extensions expand from the sealing member main body into the recess, wherein the recess extensions comprise a cross- sectional area of larger than or equal to 0.25 mm2and smaller or equal to 4 mm2. For an improved mechanical fixation of the separator in the sealing member it has been found useful, that the recess walls in the sealing member main body are not flat. One or both recess walls comprise extensions directed into the recess and configured to mechanically interact with the separator. These extensions mechanically fix the separator in position and, at the same time, allow the influx of electrolyte between the extensions. This allows for a larger contact area between the electrolyte and the separator. The latter is able to increase the electrical performance of the electrolysis cell. The above defined cross-sectional areas enable a secure support of the separator and enough space for guiding the electrolyte into and through the recess.

[0047] In a further preferred embodiment of the electrolysis cell, the sealing member main body may comprise at least a cavity extending from one surface of the sealing member main body to another surface of the sealing member main body, wherein the cavity comprises a cross-sectional area of larger or equal to 100 mm2and smaller or equal to 40000 mm2. It has been found useful, to also integrate further functions in the sealing member main body. Based on the chemical composition, preferred mechanical and chemical characteristics are achieved, allowing a mechanical weakening of the sealing member main body by forming a hole in the main body. In case of a cell stack these holes may form a manifold, allowing for the distribution of educts to the cell or the removal of products from the cell. Such additional functions are not possible, because the gaskets materials according to the state of the art are either too low in elasticity or become too brittle in harsh chemical surroundings. Small sealing member main body walls are sufficient to guarantee good mechanical and chemical sealing properties. Preferably, the cavity comprises a cross-sectional area of larger or equal to 200 mm2and smaller or equal to 20000 mm2., further preferred, a cross-sectional area of larger or equal to 450 mm2and smaller or equal to 10000 mm2. These cross-sectional areas are in the right range to provide a sufficient media supply to and from the cell and, at the same time, do not weaken the gasket characteristics too much.

[0048] Within a preferred aspect of the electrolysis cell, the sealing member is in contact with the anode support and the cathode support and at least an extension part of the sealing member extends to and beyond a contact surface of the anode support and the cathode support to an electrolysis cell surrounding. Besides providing a mechanical sealing of the electrolyte within the electrolysis cell, it is also possible to use the sealing member to electrically isolate the bipolar plates. The sealing member provides a proper electrical isolation of, for instance, bipolar plates, and also supports a mechanical protection of the bipolar plates outside of the electrolysis cell. The sealing member can extend to one or both sides out of the sealing region of the bipolar plates and can protect the outer bipolar plate circumference from a mechanical or electrical contact. Short circuits are avoided by the integration of such extended sealing member. Such additional protection is possible, because the sealing member provides the proper elastic properties, preventing any leakage of the electrolyte out of the electrolysis cell.

[0049] Within a further preferred embodiment of the electrolysis cell the anode support and / or the cathode support comprise a groove configured to encompass at least a part of the sealing member. The mechanical properties of the sealing member enable a flexible and secure sealing also in cases, wherein the sealing member is arranged within a groove in a part of the electrolysis cell. The groove may for instance be present in one or in two of the bipolar plates or electrode supports and the sealing member is at least partially arranged in the groove. The sealing member is flexible enough to provide a proper adaptation to the groove surface, even at high operational pressures in the cell, and the sealing member is also rigid enough to enable a long-term stable sealing by maintaining the same position during cell operation. Due to the fact that sealing member is chemically resistant also at harsh process conditions, there is no risk that the surface properties of the sealing member degrade over time, resulting in a failure of the sealing.

[0050] An electrolyser stack is further within the scope of the invention, wherein the electrolyser stack comprises two or more electrolysis cells according to the invention. The electrolysis cell according to the invention can preferably be used in the form of an electrolysis cell stack. Each cell of the electrolyser stack needs to be hydraulically sealed against the environment as well as (in the case of bipolar filter press design with bipolar plates) against the other cells. This requires, depending on the specific type and design of electrolyser, one or several sealing members such as gaskets, e.g. field gaskets, gaskets along the circumference of the cell, and / or internal gaskets, to seal internal feed and outlet manifolds. To withstand the harsh process conditions in AWE, i.e. hot caustics, hydrogen and oxygen, the gasket does not only need to provide sufficient sealing (i.e., a low leakage rate) but also needs to be sufficiently corrosion proof in order to minimize failure rate and maximize lifetime. The sealing member used in the inventive electrolysis cell provides the required mechanical properties and chemical resistance and, therefore, large cell stack can easily be assembled and maintained throughout the operational lifetime. Preferably, the electrolysis cell stack comprises more than 20, further preferred more than 100 and even more preferred more than 300 individual electrolysis cells. Preferably, a single cell within the cell stack may comprise a cell volume of larger than or equal to 0.015 m3and smaller than or equal to 0,2 m3.

[0051] In addition, it is further within the scope of the invention to disclose the use of a sealing member comprising a polymer blend of at least two different polymers A and B, wherein the polymer A is selected from the group consisting of polymers according to the following formula 1 , formula 1 wherein n = 10 - 20.000, m = 0, 1 or 2, each R1is independently selected from the group consisting of Cl-C3-Alkyl or a further polymer chain according to formula 1, X is independently selected from the group consisting of S, O, SO2, CH2, CO, or isomeric forms or mixtures thereof; and polymer B is selected from the group consisting of synthetic elastomeric rubbers or mixtures thereof, wherein the weight ratio of the polymers A and B in the blend, calculated as the weight of polymer A divided by the weight of polymer B, is larger than or equal to 0.3 and smaller than or equal to 5 and the weight contribution of polymer A and B in the polymer blend is larger than 70.0 weight-% or wherein the polymer A is selected from the group consisting of polysulfone, poly sulfone derivatives or mixtures thereof and polymer B is selected from the group consisting of an ethylene-propylene-diene monomer (EPDM) rubber, EPDM rubber derivative or mixtures thereof, wherein the weight ratio of the polymers A and B in the blend, calculated as the weight of polymer A divided by the weight of polymer B, is larger than or equal to 1 and smaller than or equal to 20 and the weight contribution of polymer A and B in the polymer blend is larger than 80.0 weight-%, in the sealing of alkaline water electrolysis cells, alkaline water electrolysis cell stacks, chlor-alkali electrolysis cells, chloralkali electrolysis cell stacks or heat exchanger, especially plate heat exchanger, wherein the heat exchanger modify the temperature of electrolyte originated from electrolysis cells.

[0052] Polymer A can form a continuous phase. Polymer B, and optionally other polymers, can form a disperse phase, as discussed above.

[0053] Examples and preferred embodiments of the present invention are shown and discussed in the context of the following figures.

[0054] Figure 1 shows a schematic representation of a cell-stack of two electrolysis cells according to the invention;

[0055] Figure 2 shows another schematic representation of a cell-stack of two electrolysis cells according to the invention; Figure 3 shows a schematic representation of a sealing member for sealing electrolysis cells according to the invention;

[0056] Figure 4 shows another schematic representation of a sealing member for sealing electrolysis cells according to the invention;

[0057] Figure 5 shows a schematic representation of a cell-stack of two electrolysis cells according to the invention in a top down view;

[0058] Figure 6 shows a schematic representation of a sealing member in a top view.

[0059] Figure 7 shows a schematic representation of a polymer blend used in a sealing member, according to the invention.

[0060] Figure 8 shows schematic representations of various polymer blends used in a sealing member, according to the invention.

[0061] Figure 1 shows a schematic representation of a cell-stack of two electrolysis cells 100 according to the invention. Two electrolysis cells 100 in physical contact to each other are depicted in this figure, wherein the combination of two or more electrolysis cells 100 form the stack. Each electrolysis cell 100 comprises an anode compartment with an anode 60 in contact with an anode support 10, a cathode compartment with a cathode 40 in contact with a cathode support 20. In case of the cell stack the supports 10 are present in the form of a bipolar plate. The anode 60 and cathode 40 are interchangeable by reversing the electrical polarity. In between the anode 60 and the cathode 40 a separator 50 is present and the separator 50 defines in combination with the anode support 10 and the cathode support 10 the cathode compartment and the anode compartment. The compartments can also be symmetrical in nature, i.e. the anode compartment can be the cathode compartment just by reversing the polarity of the anode / cathode 40, 60. Each compartment comprises a sealing member 20, wherein the sealing member 20 can for instance be clamped in between the anode / cathode supports. The sealing member can be in physical contact with the separator 50. The anode 60 and the cathode 40 may both be in contact with an elastic element 30, wherein this element allows for the control of the physical contact of the supports 10 and the electrodes in the form of the anode 60 and the cathode 40 and the separator 50. Based on the inventive composition of the sealing member 20, highly elastic and chemical resistant sealing members, e.g. in the form of gaskets, can be obtained. The properties of the polymer allow for instance a molding of the sealing member 20. For the sealing of electrolysis cells 100, different gaskets forms or designs can be pre-processed and the electrolysis cell 100 or the electrolysis cell 100 stack can be easily assembled. The elasticity of the sealing member 20 allows an efficient sealing of the electrolysis cell 100 even under harsh process conditions. The sealing members 20 provide an exceptional dimensional stability and the sealing members 20 can even be re-used in the course of a maintenance operation. The cell stack may provide more than 50, preferably more than 100 and more preferred more than 300 individual electrolysis cells 100. Without being bound to the theory it seems reasonable, that the outstanding mechanical and chemical properties of the sealing member 20 are based on the use of a polymer blend, wherein at least a homogeneous polymer blend of polymer A and polymer B are present. The sealing member 20 can be formed from a single peace or may be present in the form of a sealing arrangement, including more than one physical entity. The sealing member 20 also shows a recess 95 and recess extensions 96. The recess 95 is able to accommodate the separator 50, and the recess extensions 96 may alter the mechanical pressure on the separator 50 while providing electrolyte to the separator.

[0062] Figure 2 shows another schematic representation of a cell-stack of two electrolysis cells 100 according to the invention. This figure also shows the fundamental design of an electrolysis cell including bipolar plates in the form of anode / cathode support 10, the sealing member 20, an elastic element 30 in contact with the anode / cathode support and the anode 60 or the cathode and the separator 50. In this case, the sealing member 20 comprises an extension part 90. The extension part 90 comprises a further function. The overall cell compartment is sealed by the sealing member 20 and, in addition, the anode / cathode supports 10 are further isolated. It is also possible, that the extension part 90 extends beyond the bipolar plates in the form of anode support 10 and cathode support 10. In this case the anode / cathode support 10 can be protected with respect to any mechanical interference from outside of the electrolysis cell 100. In the sealing - 1 - member main body 70, a recess 95 may be present, wherein the recess 95 is adapted to interact with the separator 50. The separator 50 can be clamped between the recess 95 and the an- ode / cathode support 10 and the recess extensions 96 come in physical contact with the separator 50. Such a construction may further mechanically stabilize the separator 50 set-up. In principle, it is possible to omit the recess extensions and mechanically grip the separator by the recess 95, only. Nevertheless, the recess extensions 96 may alter the mechanical pressure on the separator 50 and enhance the contact area of the separator 50 and the electrolyte and improve the electrical performance of the electrolysis cell 100.

[0063] Figure 3 shows a schematic representation of a sealing member 20 for sealing electrolysis cells 100 according to the invention. The sealing member 20 comprises a sealing member main body 70 and sealing lips 80 extending from sealing member main body 70. In addition, an extension part 90 extends from the sealing member main body 70, wherein the extension part 90 is able to further protrude between the bipolar plates or anode / cathode supports 10. The sealing lips 80 may be used to further tailor the physical properties of the sealing member 20. The sealing lips 80 may alter the mechanical pressure for assembling the electrolysis cell 100 or for forming the overall electrolysis cell 100 stack. In this case, the sealing lips comprise an approximately rectangular cross-section. The size and the form of the sealing lips 80 cross section may be used to further tailor the mechanical stability, tightness and the forces necessary for assembling the electrolysis cell 100. In the sealing member main body 70 a recess 95 may be present, wherein the recess 95 is adapted to interact with the separator 50. The separator 50 can be clamped between the recess 95 and the anode / cathode support 10 and the recess extensions 96 come in physical contact with the separator 50 (not shown). Such a construction may further mechanically stabilize the separator 50 set-up. In principle, it is possible to omit the recess extensions and mechanically grip the separator by the recess 95, only. Nevertheless, the recess extensions 96 may alter the mechanical pressure on the separator 50 (not shown) and enhance the contact area of the separator 50 and the electrolyte and improve the electrical performance of the electrolysis cell 100. Figure 4 shows another schematic representation of a sealing member 20 for sealing electrolysis cells 100 according to the invention. The sealing member 20 can be arranged between the an- ode / cathode support 10 and comprises the same functional features as described for figure 3. The sealing member 20 comprises a sealing member main body 70, sealing lips 80 extending from the surface of the sealing member main body 70 and an extension part 90. In the sealing member main body 70 a recess 95 is present, wherein the recess 95 is adapted to interact with the separator 50 (not shown). The separator 50 can be clamped into the recess 95 and the recess extensions 96 come in physical contact with the separator 50. Such a construction may further mechanically stabilize the separator 50 set-up. In principle, it is possible to omit the recess extensions and mechanically grip the separator by the recess 95, only. Nevertheless, the recess extensions 96 may enhance the contact area of the separator 50 and the electrolyte and improve the electrical performance of the electrolysis cell 100.

[0064] Figure 5 shows a schematic representation of a cell-stack of two electrolysis cells 100 according to the invention in a top-down view. In this figure, the arrangement of the sealing members 20 can be seen.

[0065] Figure 6 shows a schematic representation of a sealing member 20 in a top view on a an- ode / cathode support 10. This specific sealing member 20 comprises additional cavities 75, wherein the cavities 75 are suitable to be used as liquid or gas manifolds interconnecting several electrolysis cells 100. The manifolds are generated by physical connecting the individual cavities 75 in the sealing members 20.

[0066] Figure 7 shows a schematic representation of a polymer blend used in a sealing member, according to the invention. Polymer A can form a continuous phase 201 and polymer B can form a disperse phase 202. Figure 8 shows schematic representations of various polymer blends used in a sealing member, according to the invention.

[0067] As shown in figure 8 a), polymer A can form a continuous phase 201, polymers B and C can form disperse phases 202, 203 within the continuous phase 201 of polymer A.

[0068] As shown in figure 8 b), polymer A can form a continuous phase 201, polymer B can form a disperse phase 202 within the continuous phase 201 of polymer A and polymer C can form a disperse phase 203 within the disperse phase 202 of polymer B.

[0069] As shown in figure 8 c), polymer A can form a continuous phase 201, polymers B, C and D can form disperse phases 202, 203, 204 within the continuous phase 201 of polymer A and polymer E can form a disperse phase 205 within the disperse phases 202, 203 of polymers B and C. These examples are shown for illustrative purposes only and are not meant to limit the scope of the invention which is defined in the appended claims.

[0070] List of References

[0071] 100 Electrolysis cell

[0072] 10 Anode / Cathode support

[0073] 20 Sealing member

[0074] 30 Elastic element

[0075] 40 Cathode

[0076] 50 Separator

[0077] 60 Anode

[0078] 70 Sealing member main body

[0079] 75 Cavity

[0080] 80 Sealing lips

[0081] 90 Extension part

[0082] 95 Recess

[0083] 96 Recess extension

[0084] 201 Continuous phase of polymer A

[0085] 202 Disperse phase of polymer B

[0086] 203 Disperse phase of polymer C

[0087] 204 Disperse phase of polymer D

[0088] 205 Disperse phase of polymer E

Claims

Claims1. Electrolysis cell (100) comprising an anode compartment with an anode (60) in contact with an anode support (10), a cathode compartment with a cathode (40) in contact with a cathode support (10), a separator (50) between the anode and the cathode compartment and a sealing member (20) for sealing an electrolyte in the anode and the cathode compartment, characterized in that the sealing member (20) comprises a polymer blend of at least two different polymers A and B, wherein the polymer A is selected from the group consisting of polymers according to the following formula 1, formula 1 wherein n = 10 - 20.000, m = 0, 1 or 2, each R1is independently selected from the group consisting of Cl-C3-Alkyl or a further polymer chain according to formula 1, X is independently selected from the group consisting of S, O, SO2, CH2, CO, or isomeric forms or mixtures thereof; and polymer B is selected from the group consisting of synthetic elastomeric rubbers or mixtures thereof, wherein the weight ratio of the polymers A and B in the blend, calculated as the weight of polymer A divided by the weight of polymer B, is larger than or equal to 0.3 and smaller than or equal to 5 and the weight contribution of polymer A and B in the polymer blend is larger than 70.0 weight-%.

2. Electrolysis cell according to claim 1, wherein polymer A is polyphenylene sulfide (PPS) or a polyphenylene sulfide derivative.

3. Electrolysis cell according to any one of the preceding claims, wherein the weight ratio of the polymers A and B in the blend is larger than or equal to 0.4 and smaller than or equal to 2.

4. Electrolysis cell according to any one of the preceding claims, wherein the polymer blend comprises a filler material in a concentration of larger than or equal to 0.5 weight-% and smaller than or equal to 20 weight-%, wherein the filler material is selected from the group consisting of ZrCh, BaSC , TiCh, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, Zirconium hydroxide, Barium hydroxide, titanium hydroxide, potassium titanate, wollastonite, ceramic whiskers, aramid-, PPS-, PSU-, PES-, PPSU-, glass-, alumina-, silicon-, carbide- , ceramic-, metal- or carbon-fibers, or mixtures of at least two members of that list.

5. Electrolysis cell according to any one of the preceding claims, wherein the sealing member (20) comprises an elastic modulus, measured according to DIN EN ISO 527-1 :2019, of larger than or equal to 0.2 GPa and smaller than or equal to 2.0 GPa.

6. Electrolysis cell according to any one of the preceding claims, wherein the sealing member (20) comprises a tensile strength, measured according to DIN EN ISO 527-1 :2019, of larger than or equal to 20 MPa and smaller than or equal to 45 MPa.

7. Electrolysis cell according to any one of the preceding claims, wherein the sealing member (20) comprises a sealing member main body (70).

8. Electrolysis cell according to claim 7, wherein the sealing member (20) comprises one or more sealing lips (80) extending from the sealing member main body (70), wherein the cross- sectional area of the sealing member main body (70) is larger than or equal to 15 mm2and smaller than or equal to 500 mm2.

9. Electrolysis cell according to claim 8, wherein the sealing lips (80) are arranged only on one surface of the sealing member main body (70).

10. Electrolysis cell according to claim 8 or 9, wherein the sealing lips (80) comprise a cross-section selected from the group consisting of trapezoidal, convex, rectangular or triangular and the cross-sectional area of the sealing lips (80) is larger than or equal to 0.5 mm2and smaller than or equal to 5 mm2.

11. Electrolysis cell according to any one of claims 7 to 10, wherein the sealing member main body (70) comprises a recess (95), wherein the recess (95) is configured to mechanically fix a part of the separator (50) to the sealing member main body (70).

12. Electrolysis cell according to claim 11, wherein one or more recess extensions (96) expand from the sealing member main body (70) into the recess (95), wherein the recess extensions (96) comprise a cross-sectional area of larger than or equal to 0.25 mm2and smaller or equal to 4 mm2.

13. Electrolysis cell according to any one of claims 7 to 12, wherein the sealing member main body (70) comprises at least a cavity (75) extending from one surface of the sealing member main body (70) to another surface of the sealing member main body (70), wherein the cavity (75) comprises a cross-sectional area of larger or equal to 100 mm2and smaller or equal to 40000 mm2.

14. Electrolysis cell according to any one of the preceding claims, wherein the sealing member (20) is in contact with the anode support (10) and the cathode support (10) and at least an extension part (90) of the sealing member (20) extends to and beyond a contact surface of the anode support (10) and the cathode support (10) to an electrolysis cell surrounding.

15. Electrolysis cell according to any one of the preceding claims, wherein the anode support (10) and / or the cathode support (10) comprise a groove configured to encompass at least a part of the sealing member (20).

16. Electrolyser stack comprising two or more electrolysis cells (100) according to any one of the preceding claims.

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