An electrolysis cell element, an electrolysis cell stack, and use of an electrolysis cell stack

Abstract

Disclosed is an electrolysis cell element (1) comprising, a support structure (2) comprising an inner aperture (3), and a bipolar plate (4) being suspended in the inner aperture (3). The support structure (2) comprises a structure core (5) and a coating (6), wherein the coating (6) includes a thermoplastic material at least partly enclosing the structure core (5) and wherein the bipolar plate (4) is suspended in the inner aperture (3) by means of the coating (6). An electrolysis cell stack (10) and use of an electrolysis cell stack (10) is also disclosed.

Description

AN ELECTROLYSIS CELL ELEMENT, AN ELECTROLYSIS CELL STACK, ANDUSE OF AN ELECTROLYSIS CELL STACKField of the invention

[0001] The invention relates to an electrolysis cell element comprising a support structure including an inner aperture and a bipolar plate. Furthermore, the invention relates to an electrolysis cell stack and use of an electrolysis cell stack.Background of the invention

[0002] In electrolysis cells and electrolysis cell stacks oxygen (02) and hydrogen (H2) is produced by electrodes - in the form of cathodes and anodes - operating in an electrolyte e.g., a liquid alkaline solution. The electrodes are separated by a diaphragm - also called a membrane separating the product gases and transporting hydroxide ions (OH-) from one electrode to the other. At least in electrolysis cell stacks, bipolar plates are arranged to ensure electrical connection between the cathodes and anodes of neighbouring cells.

[0003] Electrolysis cell stack typically comprises a number of support structures by means of which the membranes, bipolar plates and / or other components of the cell stack is fixated and between the support structures and e.g., other cell stack components sandwiched between the support structures it is known to arrange a rubber seal to ensure that the produced gasses and the electrolyte does not leak from the cell stack. However, such rubber seals are difficult to fit during assembly and vulnerable during use.

[0004] Thus, from European patent EP 2734658 B 1 it is known to cover the support structure with rubber to form this seal and to electrically insulate the support structures. However, rubber deteriorates over time when exposed to oxygen - particularly in a pressurized electrolysis system.

[0005] An object of the invention is therefore to provide for a more advantageous technique for forming an electrolysis cell element and / or an electrolysis cell stack.Summary of the invention

[0006] In an aspect, the invention relates to an electrolysis cell element comprising, a support structure comprising an inner aperture, and a bipolar plate being suspended in the inner aperture. The support structure comprises a structure core and a coating, wherein the coating includes a thermoplastic material at least partly enclosing the structure core and wherein the bipolar plate is suspended in the inner aperture by means of the coating.

[0007] Coating the structure core by means of a thermoplastic material is advantageous in that thermoplastic material is easy to mould and excellent at retaining its shape after moulding whereby is it possible to mould functional features into the coating during the moulding process or form functional features - such as complex ducts, seals, pins, depressions, flow inhibiter, turbulators or other - by means of the coating - i.e., provide the support structure with complex functional features in a simple and inexpensive way. Thus, by coating the structure core in a thermoplastic material it is possible to suspend the bipolar plate in the inner aperture of the support structure in a simple and efficient way and since another advantage of the thermoplastic material is that it is an excellent electrical insulator the coating will also ensure that the bipolar plate is electrically insulated from the structure core thus reducing the risk of getting an electric shock when touching an electrolysis cell or electrolysis cell stack containing such electrolysis cell elements. Furthermore, thermoplastic material is typically more resistant to deterioration by exposure to oxygen when the electrolysis cell element is forming part of an electrolysis cell stack - particularly a pressurized electrolysis cell system. Even further, it is advantageous to coat the structure core in a thermoplastic material in that it hereby is relatively easy to provide the support structure with the necessary production tolerances without having to machine the structure core extensively - thereby reducing production cost of the support structure.

[0008] In an exemplary embodiment of the invention, the support structure encloses the bipolar plate.

[0009] Making the support structure enclose the bipolar plate is advantageous in that the bipolar plate hereby is better supported and suspended in the support structure and in that it hereby is easier to form a strong and durable seal between neighbouring electrolysis cell element in an electrolysis cell or an electrolysis cell stack.

[0010] In an exemplary embodiment of the invention, the support structure comprises a first support structure side and a second support structure side, wherein the first support structure side is arranged on an opposite side of the support structure in relation to the second support structure side and wherein the first support structure side comprises outer sealing means arranged for sealing a primary enclosure formed by the outer sealing means when the first support structure side is pressed against a neighbouring electrolysis cell element in an electrolysis cell stack.

[0011] Making the first support structure side comprise outer sealing means is advantageous in that this makes it easy to assemble and securely seal an electrolysis cell or electrolysis cell stack containing such electrolysis cell elements.

[0012] In this context the term “sealing means” should be understood as any form of seal suited for sealing an enclosure formed by the sealing means when the side of the electrolysis cell element comprising the seal is pressed against a neighbouring electrolysis cell element in an electrolysis cell stack. I.e., the term includes any kind of gasket, O-ring, protrusion, ridge, sealant or other.

[0013] In an exemplary embodiment of the invention, the outer sealing means is extending continuously along an outer periphery of the support structure.

[0014] Making the outer sealing means extend continuously along the outer periphery of the support structure is advantageous in that this enables better utilisation of the entire support structure when used in an electrolysis cell or electrolysis cell stack.

[0015] In an exemplary embodiment of the invention, the first support structure side further comprises inner sealing means arranged for sealing a secondary enclosure formed by the inner sealing means when the first support structure side and the outersealing means is pressed against the neighbouring electrolysis cell element in an electrolysis cell stack.

[0016] Making the first support structure side also comprise inner sealing means is advantageous in that this extra seal will further reduce the risk of leakage when the electrolysis cell element is used in an electrolysis cell or electrolysis cell stack.

[0017] In an exemplary embodiment of the invention, the inner sealing means is enclosed by the outer sealing means so that an intermediate enclosure is formed between the inner sealing means and the outer sealing means when the first support structure side is pressed against the neighbouring electrolysis cell element in an electrolysis cell stack.

[0018] Forming an intermediate enclosure between the inner sealing means and the outer sealing means is advantageous in that this intermediate enclosure can be used for detecting the condition of the seals e.g., by raising the pressure in the intermediate enclosure, by detecting leakage into the intermediate enclosure, by detecting leakage out of the intermediate enclosure or other.

[0019] In an exemplary embodiment of the invention, the outer sealing means and / or the inner sealing means is formed integrally with the coating.

[0020] Forming the outer sealing means and / or the inner sealing means as an integrated part of the coating is advantageous in that this is a simple, efficient and inexpensive way of forming the sealing means.

[0021] In an exemplary embodiment of the invention, the outer sealing means and / or the inner sealing means is formed as a sealing protrusion protruding from the first support structure side.

[0022] Forming the outer sealing means and / or the inner sealing means as sealing protrusions protruding from the first support structure side is advantageous in that these sealing protrusions hereby will be forced harder against a neighbouring electrolysis cell element when the electrolysis cell elements are pressed against each other and in that it hereby is possible, in a simple manner, to form conduits betweendifferent sealing protrusions such as the outer sealing means and the inner sealing means.

[0023] In an exemplary embodiment of the invention, the support structure comprises an alignment protrusion and an alignment aperture, wherein the alignment protrusion is arranged for engaging a corresponding alignment aperture of a neighbouring electrolysis cell element in an electrolysis cell stack.

[0024] Providing the support structure with an alignment protrusion and an alignment aperture is advantageous in that it hereby is easier to align neighbouring electrolysis cell elements correctly when forming an electrolysis cell stack of these electrolysis cell elements.

[0025] In an exemplary embodiment of the invention, the alignment protrusion is formed by the coating.

[0026] Forming the alignment protrusion as an integrated part of the coating is advantageous in that this is a simple, efficient and inexpensive way of forming the alignment protrusion.

[0027] In an exemplary embodiment of the invention, the coating is electrically insulating.

[0028] Forming the coating of an electrically insulating material is advantageous in that the bipolar plate - which is used as an electrical conductor during use - is electrically insulated from the structure core whereby the risk of getting an electric shock when touching the support structure is reduced or eliminated.

[0029] In an exemplary embodiment of the invention, the structure core is made of metal, such as steel.

[0030] Forming the structure core from metal is advantageous in that metal is a strong, durable and relatively inexpensive material that relatively easily can be moulded or machined into the desired shape.

[0031] In an exemplary embodiment of the invention, the structure core is formed monolithic.

[0032] Forming the structure core monolithic - i.e., from a single piece of material - is advantageous in that a structure core without joints can be formed stronger and / or lighter thereby reducing costs and / or weight.

[0033] In an exemplary embodiment of the invention, the thermoplastic material is selected from a group consisting of: Polypropylene (PP), Polyethylene (PE), Polyphenylene sulphide (PPS), Polysulfone (PSU) and Polyphenyl sulfone (PPSU).

[0034] A common quality of PP, PE, PPS, PSU and PPSU is that these thermoplastic materials are all excellent electrical insulators that are easy to mould and thereby particularly suited for suspending a bipolar plated inside the centre aperture of a support structure. Furthermore, a common quality is that these thermoplastic materials are very resistant to deterioration due to the oxygen exposure the material is exposed to in an operating electrolysis cell stack comprising several electrolysis cell elements.

[0035] In an exemplary embodiment of the invention, the coating is enclosing between 50% and 100%, preferably between 65 and 99%, and most preferred between 80% and 99% of the structure core.

[0036] Coating a majority of the surface area of the structure core by means of the coating is advantageous in that this reduces the risk of the structure core getting in electrical contact with electrically conducting parts of the electrolysis cell stack during use and it provides better protection of structure core from harmful fluids during use in an operating electrolysis cell stack. Thus, the present coating ranges are advantageous in relation to functionality and durability.

[0037] In a further aspect, the invention relates to an electrolysis cell stack comprising, a plurality of electrolysis cell elements according to any of the previously discussed electrolysis cell elements, a plurality of cathodes, a plurality of anodes, a plurality of gas impermeable membranes, and pressing means arranged for pressingneighbouring electrolysis cell elements of the plurality of electrolysis cell elements against each other.

[0038] Forming an electrolysis cell stack by means of the previously discussed electrolysis cell elements, and cathodes, anodes, gas impermeable membranes, and pressing means is advantageous in that the bipolar plates suspended in the support structures to conduct electricity between neighbouring cathodes and anodes hereby can be electrically insulated from other parts of the cell stack in a simple and inexpensive way and in that electrolysis cell stack can be formed more inexpensive and durable because further technical features can be formed by means of the thermoplastic material.

[0039] In this context the term “pressing means” should be understood as any form of press suited for pressing neighbouring electrolysis cell elements against each other in an electrolysis cell or electrolysis cell stack. I.e., the term includes any kind of hydraulic press, pneumatic press, tie rod, bolts, brace or other.

[0040] Furthermore, in this context the term “gas impermeable” should be understood as the membrane being substantially impermeable to gas during normal use in an electrolysis cell stack. However, in certain other circumstances - e.g., if the gas impermeable membrane is not submerged in electrolyte (i.e., if the gas impermeable membrane is dry) - the membrane could - in these “unnormal” situations - be at least partly permeable to gas.

[0041] In another aspect, the invention relates to use of an electrolysis cell stack according to the preceding claim in a pressurized electrolysis system which is configured to produce hydrogen and / or oxygen.

[0042] Using the electrolysis cell stack in a pressurized electrolysis system is particularly advantageous in that the thermoplastic material coating does not deteriorate (like e.g., rubber) when exposed to oxygen - particularly pressurized oxygen - making the electrolysis system more durable and less prone to leaks.The drawings

[0042] For a more complete understanding of this disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts. The drawings illustrate embodiment of the invention and elements of different drawings can be combined within the scope of the invention:Fig. 1 illustrate elements of a part of an electrolysis cell stack in a perspective view according to an embodiment of the invention,Fig. 2 illustrates an electrolysis system according to an embodiment of the invention,Fig. 3 illustrates a front view of an electrolysis cell element according to an embodiment of the invention,Fig 4 illustrates a side view of a cross section down the middle of the electrolysis cell element disclosed in fig. 3, andFig. 5 illustrates a an enlarges cutout of the electrolysis cell element disclosed in fig. 4.Detailed description

[0043] The present invention is described in view of exemplary embodiments only intended to illustrate the principles and implementation of the present invention. The skilled person will be able to provide several embodiments within the scope of the claims.

[0045] Fig. 1 illustrates an example of a part of an electrolysis cell stack 10 of an electrolysis system 21 according to an embodiment of the invention. In this embodiment the electrolysis cell stack 10 comprises a plurality of similar adjacent electrolysis cells that are forced together by pressing means 20 e.g., in the form of hydraulics, bolts and nuts, spindles or similar arrangements (see fig. 2).

[0046] In this embodiment electrolysis cell stack 10 comprises a plurality of bipolar plates 4 suspended inside an inner aperture 3 of a support structure 2. The bipolar plate 4 may be a metal or plastic plate that is forming a gas and liquid tight barrier separating flow of gas and electrolyte on the two sides of the electrolysis cell element 1. Thus, the bipolar plate 4 fully prevents fluid flow across the electrolysis cell element 1.

[0047] In a compartment 24 on one side of the bipolar plate 4 an anode 18 is arranged and this compartment 24 is therefore referred to as an anode compartment 24. In the compartment 25 on the other side of the bipolar plate 4 a cathode 17 is arranged and this compartment 25 is therefore referred to as an anode compartment 25. Thus, in this embodiment a bipolar plate 4 forms an end wall of an anode compartments 24 and another bipolar plate 4 forms an end wall of a cathode compartments 25. The other end wall of each of these compartments 24, 25 is in this embodiment formed by a gas impermeable membrane 19.

[0048] In this embodiment the anodes 18 and cathodes 17 are electrically connected by means of the bipolar plate 4. In fig. 1, the bipolar plates 4 are illustrated with a plurality of circles which is intended to illustrate the part of the bipolar plate 4 that is electrically connected to the electrodes - i.e., the anodes 18 and cathodes 17. Thus, in this embodiment the electrolysis cell stack 10 will alternately comprise an anode compartment 24 and a cathode compartment 25. In this embodiment the electrical connection between electrodes 17, 18 and bipolar plates 4 is formed by means of spot welding, but in another embodiment the electrical connection could be established by means of regular welding, soldering, mechanical connections (screws, bolts, rivets etc.), wires or other.

[0049] In this embodiment two electrolysis cell elements 1 of the electrolysis cell stack 10 is shown, wherein each of the electrolysis cell elements 1 in this embodiment comprise an anode compartment inlet 22 and anode compartment outlet 23 being in fluid communication with the anode compartment 24 formed inside the stack 10, and a cathode compartment inlet 28 and cathode compartment outlet 29 being in fluid communication with the cathode compartment 25 also formed inside the stack 10. The inlets 22, 28 are in this embodiment located towards the bottom part of the electrolysiscell element 1 and is supplying the compartments 24, 25 with electrolyte (also referred to as lye). The compartments 24, 25 is where the electrolysis process happens i.e., the production of the gaseous hydrogen or oxygen. The produced hydrogen and oxygen are leaving the compartments 24, 25 via the outlets 23, 29 located towards the top part of the electrolysis cell element 1.

[0050] The anode compartment outlet 23 from one anode compartment 24 will in this embodiment together with anode compartment outlets 23 of other electrolysis cell elements 1 form an anode / oxygen manifold 26. In the same way, the cathode compartment outlet 23 from a cathode compartment 25 will in this embodiment together with cathode compartments outlets 29 of other electrolysis cell elements 1 form a cathode / hydrogen manifold 27.

[0051] Accordingly, a bipolar plate 4 of one electrolysis cell element 1 is on one side electrically connected to an anode 18 and on the other side electrically connected to the cathode 17, thus the bipolar plate 4 facilitates an electric connection between an anode 18 of a first cell and a cathode 17 of a second cell. As illustrated in fig. 1 the bipolar plate 4 of the left most electrolysis cell element 1 is on its left side connected to an anode 18 forming part of an adjacent cell and on its right side connected to the cathode 17 forming part of the illustrated cell. Similarly, the bipolar plate 4 of the right most electrolysis cell element 1 on fig. 1 is on its left side connected to the anode 18 forming part of the illustrated cell and on its right side connected to a cathode forming part of an adjacent cell.

[0052] In the electrolysis cell stack 10 the electrolysis cell elements 1 are forced together, e.g., via threaded rods and bolts (see fig. 2), with a gas impermeable membrane 19 therebetween. The gas impermeable membranes 19 are impermeable to gases such as hydrogen and oxygen (non-polar components) but allow passage of water and polar components (ions). Accordingly, the electrolysis cell element 1 is facilitating structural support for the compartments 24, 25. The compartments 24, 25 being defined by the bipolar plate 4 and the gas impermeable membranes 19 and establishes a fluid flow path from the compartment inlets 22, 28, through each of the compartments 24, 25 to the compartment outlets 23, 29.

[0053] In this embodiment the inlets 22, 28 to respective the compartments 24, 25 are designed to establish an even distribution of electrolyte in the compartments 24, 25 to ensure optimal gas production and optimal cooling of the compartments 24, 25. The outlets 23, 29 from the respective compartments 24, 25 should be designed to effectively evacuated gas from the compartments 24, 25 and thereby ensure that no gas pocket occurs in the compartments 24, 25. This is not desired because it will reduce efficiency of the cell stack 10 and there will be a risk of gas migrating or passing the gas impermeable membrane 19.

[0054] The gas production starts when a current is allowed to flow through the electrolysis cell stack 10. More specific, when a negative potential of a direct current power supply is applied to a cathode 17 in one end of an electrolysis cell stack 10 and a positive potential of the direct current power supply is applied to an anode 18 in the other end of the electrolysis cell stack 10.

[0055] In an embodiment, the electrolyte is an alkaline electrolyte established by adding a strong base to demineralized water such as potassium hydroxide (KOH) producing K+ cations and OH- anions when the DC power is applied. The alkaline electrolyte facilitates transport of negatively charged ions OH- through the gas impermeable membranes 19 and thus hydrogen and oxygen are produced at the electrodes according to the general principle of electrolysis (see eql and eq2 below).

[0056] Water molecules are dissociated at the cathode into H+ and OH-. Further, due to the presence of electrons e- from the direct current power source, a recombination of H+ into gaseous H2 is facilitated according to eql (1 = liquid, g = gas, ag = aqueous).EQI : 2 H2O (1) + 2 e- H2 (g) + 2 OH- (aq)

[0057] The gaseous hydrogen H2, travels upwards in the cathode compartment 25 and leaves - typically together with some electrolyte 32 - the cathode compartment 25 via the cathode compartment outlet 29.

[0058] The OH- ions in the electrolyte are attracted towards the anode 18 by the electric field and is allowed to pass through the gas impermeable membranes 19. Asmentioned, the gas impermeable membranes 19 ensures that no hydrogen or oxygen can pass, but the OH- ions can travel from the cathode compartment 25 to the anode compartment 24. At the anode 18, OH- anions are oxidised and producing oxygen while releasing electrons e- (seen eq2).EQ2: 2 OH- (aq)102 (g) + H2O (I) + 2 e-

[0059] The gaseous oxygen 02 travels upwards in the anode compartment 24 and leaves - typically together with some electrolyte 32 - the anode compartment 24 via the anode compartment outlet 23.

[0060] It should be mentioned that the electrolysis cell stack part and its components illustrated in fig. 1 is only one example of an electrolysis cell stack 10 / electrolysis cell element 1 of the present invention. Other geometric shapes may be suitable. Alternative locations of the anodes 18, cathodes 17 and gas impermeable membranes 19 may be relevant. Further it should be mentioned that an electrolysis cell element 1 according to the invention may be used for both gapped and zero-gap electrolysis cell stacks 10.

[0061] The gas impermeable membrane 19 is as mentioned impermeable to gases but must be selectively permeable to ions. Therefore, it may be of a hydrophilic material that attracts water or other polar components, like OH-, but repels non-polar components like H2 or 02. As a non-limiting example, the gas impermeable membrane 19 may be made of an open mesh polyphenylene sulphide fabric, which is coated with a mixture of polysulfone and of zirconium oxide. The gas impermeable membrane 19 may have a thickness between 0.2mm and 0.9mm such as 0.5 mm, a porosity of 55%, the same density as water and an operating temperature between 75°C and 110°C such as 80°C.

[0062] The electrodes 17, 18 may be made of a corrosion-resistant metal. The oxygen-producing anode 18 may be made of e.g., nickel, a nickel coating on a steel core or of a nickel-iron alloy coated on a simple steel or nickel plate. The hydrogenproducing cathode 17 may generally be made of a steel core with some catalytic coating. Such coatings may include plain unactivated nickel, activated nickel alloys(NiMo, NiSn, NiS) or even platinum group metals. The electrodes 17, 18 may be either solid or use thin, porous or perforated plates. For example, a thin 0.3mm pure nickel plate with 50% perforation can be used for the anode 18, while a similarly thin 0.3mm perforated nickel plate coated with NiS can be used for the cathode 17.

[0063] Fig. 2 illustrates an electrolysis system 21 according to an embodiment of the invention which in this embodiment comprises an electrolysis cell stack 10 formed by a plurality of electrolysis cell elements 1, a plurality of cathodes 17, a plurality of anodes 18, and a plurality of gas impermeable membranes 19 held and forced together by pressing means 20 which in this embodiment comprises threaded rods 30 and nuts 31 forcing two endplates of the stack 10 against each other to press neighbouring electrolysis cell elements 1 against each other.

[0064] As mentioned, the gas leaves the stack 10 via the upper manifolds 26, 27. The gas from each manifold 26, 27 is separated from the electrolyte 32 which is subsequently recirculated. In this embodiment the electrolysis system 21 also comprises an oxygen storage 36 to which the produced oxygen is led and a hydrogen storage 37 to which the produced hydrogen is led. As the gas separation is not essential for the invention, this is not described in further details.

[0065] In this embodiment the electrolysis system 21 comprises a vessel 33 to which the recirculated electrolyte 32 is led and in this embodiment demineralized water 34 and a base 35 - in this case potassium hydroxide - is mixed in the vessel 33 to form an electrolyte 32 which is led into the electrolysis cell stack 10 to enter the compartments 24, 25 through the compartment inlets 22, 28. In this embodiment the electrolysis cell stack 10 also comprise electrolyte pump means 38 - in this case in the form of a pump - arranged for controlling the flow speed of the electrolyte 32 and in another embodiment the electrolysis cell stack 10 could also comprise a heat exchanger for temperature regulation of the electrolyte 32 for increasing or decreasing the temperature of the electrolyte 32 before it is guided into the electrolysis cell stack 10. In another embodiment the electrolyte pump means 38 could be provided elsewhere in the circuit or the circulation could be driven by the gas production in the electrolysis cell stack 10.

[0066] The flow speed of gas vs electrolyte fraction is advantageous to control in that in this way it is possible to control the volume of electrolyte in the outlet manifolds 26, 27. Thus, the gas / electrolyte fraction can be controlled in various ways requiring a process system (not illustrated) which comprises a controller, pumps, sensors, valves, meters, etc.

[0067] Non-limiting examples of control of gas vs electrolyte fraction can be by controlling the power supply. This is because there is a relationship between gas production and power consumption. Alternatively, or in addition, the gas vs electrolyte fraction can be controlled by controlling the pressure in the electrolysis cell stack 10 or the flow of quantity of electrolyte 32 per unit time into the electrolysis cell stack 10.

[0068] An electrolysis system 21 is typically designed to operate at a given pressure and temperature based on a trade-off between output and cost. In this embodiment the electrolysis system 21 is designed to operate at a pressure at around 15-20 Bar but in another embodiment the electrolysis system 21 could be designed to operate at a lower pressure - such as 9- 14 Bar, 5-8 Bar, 2-4 Bar or even unpressurized - or the electrolysis system 21 could be designed to operate at a higher pressure - such as 25-35 Bar, 30- 70 Bar, 80-150 Bar or even higher. As a general rule the higher operation pressure, the more expensive electrolysis system 21 but at high pressure the gas is compressed in the stack 10 and thus higher gas production can be expected and less cost to compress the gas subsequently can be expected.

[0069] Fig. 3 illustrates a front view of an electrolysis cell element 1 according to an embodiment of the invention. In this embodiment the electrolysis cell element 1 comprises a support structure 2 formed with an inner aperture 3 in which a bipolar plate 4 is suspended so that the bipolar plate 4 forms an impermeable wall in the aperture 3. As better seen in figs. 4 and 5 the support structure 2 is in this embodiment formed by a structure core 5 provided with a coating 6 arranged so that the bipolar plate 4 is suspended in the inner aperture 3 by means of this coating 6.

[0070] In this embodiment the visible first support structure side 7 of the support structure 2 comprises outer sealing means 9 forming a primary enclosure when thefirst support structure side 7 is pressed against a neighbouring electrolysis cell elementI in an electrolysis cell stack 10 and the first support structure side 7 does in this embodiment further comprise inner sealing means 12 sealing a secondary enclosure inside the primary enclosure when the first support structure side 7 is pressed against the neighbouring electrolysis cell element 1 in an electrolysis cell stack 10 so that an intermediate enclosure 13 is formed between the inner sealing means 12 and the outer sealing means 9. However, in another embodiment the support structure 2 would only comprise the outer sealing means 9, the support structure 2 would only comprise the inner sealing means 12, the support structure 2 would not comprise any sealing means 9, 12 or the support structure 2 would comprise further sealing means. In this embodiment outer sealing means 9 is extending continuously along an outer peripheryI I of the support structure 2 but in another embodiment the outer sealing means 9 could be arranged elsewhere on the support structure 2 - such as closer to the inner aperture 23, it could be waving e.g., to pass obstacles or other.

[0071] As a non-limiting example, the outer diameter of the electrolysis cell element1 is in this embodiment around 950 mm. However, in another embodiment the outer diameter of the electrolysis cell element 1 could be bigger - such as 1,200 mm, 1,800 mm, 2,300 mm or even bigger - or smaller such as 820 mm, 690 mm, 510 mm or even smaller, e.g., depending on the electrolysis cell stack 10 capacity, manufacturing options, available space or other.

[0072] Fig 4 illustrates a side view of a cross section down the middle of the electrolysis cell element 1 disclosed in fig. 3. In this embodiment the support structure2 comprises a first support structure side 7 and a second support structure side 8 opposite the first support structure side 7 and in this embodiment the outer sealing means 9 and the inner sealing means 12 (seen more clearly in fig. 5) is only arranged on the first support structure side 7. However, in another embodiment the outer sealing means 9 and / or the inner sealing means 12 could also or instead be arranged on the second support structure side 8.

[0073] In this embodiment the width of one electrolysis cell element 1 is around 16 mm. However, in another embodiment the width of the electrolysis cell element 1could be bigger - such as 20 mm, 25 mm, 30 mm or even bigger - or smaller such as 14 mm, 12 mm, 10 mm or even smaller, e.g., depending on the electrolysis cell stack 10 capacity, manufacturing options, available space or other. An electrolysis cell stack 10 may comprise from two electrolysis cell element 1 to several hundred electrolysis cell element 1 such as from up to 100, 150, 200, 230, . . .500 or even more electrolysis cell element 1. Hence, the length of an electrolysis cell stack 10 may be from around 40 mm to e.g., 10 meters. Several stacks 10 may be connected in series or in parallel. The design of an electrolysis cell stack 10 may be determined by voltage and thus requirements to the power supply of the electrolysis system 21. Further stack design parameters may be depending on available space, required capacity, etc.

[0074] Fig. 5 illustrates a an enlarges cutout of the electrolysis cell element 1 disclosed in fig. 4. In this embodiment the outer sealing means 9 and the inner sealing means 12 are formed integrally with the coating 6 in that the sealing means 9, 12 are formed as sealing protrusions 14 protruding from the first support structure side 7, wherein these sealing protrusions 14 are formed during the process (e.g., moulding process) by which the coating 6 is applied to the structure core 5. However, in another embodiment the sealing means 9, 12 could be formed integrally with the coating 6 though a subsequent machining process, the sealing means 9, 12 could be moulded into the coating 5, the sealing means 9, 12 could be connected to the coating 5, the sealing means 9, 12 could be resting against the coating 5 and / or the sealing means 9, 12 could be formed by the entire surface of the coating 5 being forced against a neighbouring electrolysis cell element 1 in a electrolysis cell stack 10.

[0075] In this embodiment the support structure 2 further comprises two alignment protrusions 15 and two alignment apertures 16 arranged so that when the first support structure side 7 of the electrolysis cell element 1 is forced against a second support structure side 8 of a neighbouring electrolysis cell element 1 in a electrolysis cell stack 10 the alignment protrusions 15 will engage the corresponding alignment apertures 16 in the neighbouring electrolysis cell element 1 so that the electrolysis cell elements 1 are fully aligned. However, in another embodiment the electrolysis cell element 1could comprise another number of alignment protrusions 15 and alignment apertures 16 - such as one, three, five eight or even more.

[0076] In this embodiment the alignment protrusions 15 are formed integrally with the coating 6 in that the alignment protrusions 15 are formed during the process (e.g., moulding process) by which the coating 6 is applied to the structure core 5. However, in another embodiment the alignment protrusions 15 could be formed integrally with the coating 6 though a subsequent machining process, the alignment protrusions 15 could be connected to the coating 5, the alignment protrusions 15 could be formed by the structure core 5 and / or the alignment protrusions 15 could be enabled in another way.

[0077] In this embodiment the structure core 5 is made of steel but in another embodiment the structure core 5 could also or instead be made of another metal - such as aluminium, stainless steel, brass and / or other - and / or the structure core 5 could comprise another material - such as a composite material, plastic, ceramic, glass and / or other.

[0078] In this embodiment the structure core 5 is formed monolithic - i.e., in this embodiment the structure core 5 is formed from a single piece of material - but in another embodiment the structure core 5 could be formed by several parts e.g., connected by means of mutually engaging geometry, screws, bolt, rivets, adhesive or other.

[0079] In this embodiment the coating is made of a thermoplastic material in the form of Polypropylene (PP) but in another embodiment the thermoplastic material could be Polyethylene (PE), Polyphenylene sulphide (PPS), Polyphenyl sulfone (PPSU) or another polymeric thermoplastic material, e.g., depending on the specific use, the specific moulding technique, the operating pressure of the electrolysis cell stack 10 or other.

[0080] In this embodiment the coating 6 is electrically insulating and in this embodiment the bipolar plate 4 is suspended in the inner aperture 3 exclusively by means of the coating 6 so that in this embodiment the bipolar plate 4 is fully electricallyinsulated from the structure core 5. In this embodiment the bipolar plate 4 is connected to the structure core 5 by means of the coating 6 during the process (e.g., moulding process) by which the coating 6 is applied to the structure core 5. However, in another embodiment the bipolar plate 4 could be connected to the structure core 5 by means of the coating 6 though a subsequent assembly process.

[0081] In this embodiment the coating 6 in this embodiment is enclosing around 98% of the surface of the structure core 5 the coating 6, and the only part of the structure core 5 not being enclosed by the coating is in this embodiment the small taps 39 arranged along the outer periphery of the structure core 5, in that these taps 39 are used for fixating the structure core 5 during the process of applying the coating 6 to the structure core 5. However, in another embodiment the structure core 5 could be fully enclosed by the coating 6 or the coating 6 would enclose less of the structure core 5 - such as only 92%, 74%, 56% or even less.

[0082] The invention has been exemplified above with reference to specific embodiments. Details of specific embodiment have been provided in order to understand the aim of the invention and can be combined where appropriate. Please note, that detailed descriptions of well-known systems, devices, circuits, and methods have been omitted so as to not obscure the description of the invention with unnecessary details.List1. Electrolysis cell element2. Support structure3. Inner aperture4. Bipolar plate5. Structure core6. Coating7. First support structure side8. Second support structure side9. Outer sealing means10. Electrolysis cell stack11. Outer periphery of support structure12. Inner sealing means13. Intermediate enclosure14. Sealing protrusion15. Alignment protrusion16. Alignment aperture17. Cathode18. Anode19. Gas impermeable membrane20. Pressing means21. El ectroly si s sy stem22. Anode compartment inlet23. Anode compartment outlet24. Anode compartment25. Cathode compartment26. Anode / oxygen manifold27. Cathode / oxygen manifold28. Cathode compartment inlet29. Cathode compartment outlet30. Rod31. Nut32. Electrolyte33. Vessel34. Water35. Base36. Oxygen storage37. Hydrogen storage38. Electrolyte pump means39. Tap

Claims

Claims1. An electrolysis cell element (1) comprising, a support structure (2) comprising an inner aperture (3), and a bipolar plate (4) being suspended in said inner aperture (3), wherein said support structure (2) comprises a structure core (5) and a coating (6), wherein said coating (6) includes a thermoplastic material at least partly enclosing said structure core (5) and wherein said bipolar plate (4) is suspended in said inner aperture (3) by means of said coating (6).

2. An electrolysis cell element (1) according to claim 1, wherein said support structure (2) encloses said bipolar plate (4).

3. An electrolysis cell element (1) according to claim 1 or 2, wherein said support structure (2) comprises a first support structure side (7) and a second support structure side (8), wherein said first support structure side (7) is arranged on an opposite side of said support structure (2) in relation to said second support structure side (8) and wherein said first support structure side (7) comprises outer sealing means (9) arranged for sealing a primary enclosure formed by said outer sealing means (9) when said first support structure side (7) is pressed against a neighbouring electrolysis cell element (1) in an electrolysis cell stack (10).

4. An electrolysis cell element (1) according to claim 3, wherein said outer sealing means (9) is extending continuously along an outer periphery (11) of said support structure (2).

5. An electrolysis cell element (1) according to claim 3 or 4, wherein said first support structure side (7) further comprises inner sealing means (12) arranged for sealing a secondary enclosure formed by said inner sealing means (12) when said first support structure side (7) and said outer sealing means (9) is pressed against said neighbouring electrolysis cell element (1) in an electrolysis cell stack (10).

6. An electrolysis cell element (1) according to claim 5, wherein said inner sealing means (12) is enclosed by said outer sealing means (9) so that an intermediate enclosure (13) is formed between said inner sealing means (12) and said outer sealing means (9) when said first support structure side (7) is pressed against said neighbouring electrolysis cell element (1) in an electrolysis cell stack (10).

7. An electrolysis cell element (1) according to any of claim 3-6, wherein said outer sealing means (9) and / or said inner sealing means (12) is formed integrally with said coating (6).

8. An electrolysis cell element (1) according to any of claim 3-7, wherein said outer sealing means (9) and / or said inner sealing means (12) is formed as a sealing protrusion (14) protruding from said first support structure side (7).

9. An electrolysis cell element (1) according to any of the preceding claims, wherein said support structure (2) comprises an alignment protrusion (15) and an alignment aperture (16), wherein said alignment protrusion (15) is arranged for engaging a corresponding alignment aperture (16) of a neighbouring electrolysis cell element (1) in an electrolysis cell stack (10).

10. An electrolysis cell element (1) according to claim 9, wherein said alignment protrusion (15) is formed by said coating (6).

11. An electrolysis cell element (1) according to any of the preceding claims, wherein said coating (6) is electrically insulating.

12. An electrolysis cell element (1) according to any of the preceding claims, wherein said structure core (5) is made of metal, such as steel.

13. An electrolysis cell element (1) according to any of the preceding claims, wherein said structure core (5) is formed monolithic.

14. An electrolysis cell element (1) according to any of the preceding claims, wherein said thermoplastic material is selected from a group consisting of: Polypropylene (PP),Polyethylene (PE), Polyphenylene sulphide (PPS), Polysulfone (PSU) and Polyphenyl sulfone (PPSU).

15. An electrolysis cell element (1) according to any of the preceding claims, wherein said coating (6) is enclosing between 50% and 100%, preferably between 65 and 99%, and most preferred between 80% and 99% of said structure core (5).

16. An electrolysis cell stack (10) comprising, a plurality of electrolysis cell elements (1) according to any of the preceding claims, a plurality of cathodes (17), a plurality of anodes (18), a plurality of gas impermeable membranes (19), and pressing means (20) arranged for pressing neighbouring electrolysis cell elements (1) of said plurality of electrolysis cell elements (1) against each other.

17. Use of an electrolysis cell stack (10) according to claim 16 in a pressurized electrolysis system (21) which is configured to produce hydrogen and / or oxygen.

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