Bipolar plate and electrodes assembly and method for generating a bipolar plate and electrodes assembly and electrolyser unit adapted for electrolysing water into hydrogen and oxygen

Abstract

A bipolar plate and electrodes assembly where the bipolar plate is connected to an electrode through a number of distance units is thus suggested whereby the distance units are singular, and that further, between each singular distance unit and at least one of the bipolar plate and the electrode a fusion zone is / are provided. The invention also comprises a method for generating a bipolar plate and electrodes assembly. Further an electrolyser adapted for electrolysing water into oxygen and hydrogen, is provided, whereby the electrolyser comprises a cell stack having alternatingly a diaphragm and a bipolar plate and electrode assembly and the assembly is comprised of a number of singular distance units interposed between and interconnecting bipolar plate and respective cathode and anode electrode, which distance units are adapted to be generated by way of one or more distance unit controlled generators during an assembly and fusion process.

Description

[0001] BIPOLAR PLATE AND ELECTRODES ASSEMBLY AND METHOD FOR GENERATING A BIPOLAR PLATE AND ELECTRODES ASSEMBLY AND ELECTROLYSER UNIT ADAPTED FOR ELECTROLYSING WATER INTO HYDROGEN AND OXYGEN

[0002] Background of the invention

[0003] The bipolar plate and electrode assemblies are used in electrolysers, such as water electrolysers adapted for producing hydrogen and oxygen by splitting water. Electrolysers of this kind may pre-pressurize the electrolyte and may work on pure water or work on an alkaline water composition or may work with water steam or supercritical water as the electrolyte.

[0004] In a prior art assembly of bipolar plate and electrodes, distance units are usually provided between the electrode and the bipolar plate and are comprised of so- named bumps or protrusions made in the bipolar plate and directed in normal directions away from the plate. At each side of a bipolar plate, an electrode is fastened, such as by being welded onto the top of the protrusions which extends in one direction, and an electrode is similarly fastened onto the top of protrusions which extends in the opposite direction.

[0005] As the protrusions are all of equal height away from the bipolar plate, the two electrodes will extend in parallel with the bipolar plate and equally distanced therefrom. At the top of the protrusions where the electrodes are welded to the bipolar plate, flow between a diaphragm and the electrode is somewhat hampered due to the protrusion, and this effect is referred to as shadowing, and the assumption is that the shadow effect shall hamper electrolysis at the welding points. The diaphragm is inserted between adjacent assemblies of bipolar plate and electrodes to ensure that the produced gasses at the electrodes on either side of the bipolar plate do not get mixed.

[0006] The distance between bipolar plate and electrodes allows a process fluid, such as water or alkaline rich water to flow along each electrode between an inlet and an outlet provided at electrode edge parts. At or on surfaces of the electrodes the product gasses are produced, namely oxygen at one side of the bipolar plate and hydrogen at the opposed side and the gasses are guided to respective outlets.

[0007] It is desired, that a predefined pressure force continually presses each electrode towards the diaphragm, meaning that the electrodes at each side of a diaphragm, anode and cathode respectively, should be pressed with a predetermined pressure force towards each other and thus towards the diaphragm arranged between then. In this way a zero distance or possibly well-defined non-zero distance between each electrode and its accompanying diaphragm will be more accurately reached. It should be emphasized, that the pressure forces at each side of the diaphragm are to work against each other, and thus outbalance each other and the diaphragm shall thus not move as a result of these pressures.

[0008] Between each assembly of a bipolar plate and accompanying electrodes, a diaphragm is provided, and the bipolar plate and electrodes are arranged such that at a first side of a diaphragm an anode shall reside, and at an opposed side a cathode shall reside.

[0009] Summary of the invention

[0010] A bipolar plate and electrodes assembly where the bipolar plate is connected to an electrode through a number of distance units is thus suggested whereby according to the invention the distance units are singular, and that further, between each singular distance unit and at least one of the bipolar plate and the electrode a fusion zone is / are provided.

[0011] By this arrangement it becomes possible to provide the distance units at one side of the bipolar plate independent from the placement of distance units at an opposed side. Thus, distance units may be placed in alignment with each other on the two opposed sides of the bipolar plate, or they may be placed in misalignment if this is preferred. Further, the distance units may be more freely shaped to firstly not hamper flows of electrolyte along the bipolar plate and electrode, and to secondly ensure reduced shadow effect. It becomes possible to provide distance elements with a degree of resilience such as by being shaped as springs or the like elements. With bumps or dimples or the like protrusions shaped in the bipolar plate material, resilience or spring like action is also possible however, this requires more intricate shapes which are not in any way easy to provide without formation of cracks or even rifts in the bipolar plate material, and thus remains as of now mostly a theoretical possibility. It has been suggested to use a ceramic element as diaphragm, and in such cases, it is especially important, that the distance units providing pressure from either side of a diaphragm are aligned. Freely positionable distance unit makes this an easy target to meet. It is to be understood that the term “singular” in this connection is to be understood as an element, which at some point during manufacture of the bipolar plate and electrodes assembly is not attached to or part of either electrode or the bipolar plate.

[0012] It is also an object of the invention to increase the variety of options such increased choices with respect to placement of distance units on the bipolar plate, and options regarding choice of construction material for the distance units.

[0013] [2] In an embodiment the fusion zone is adapted to be established via resistance or spot welding, laser welding, electron beam welding, friction welding, combustion- or chemical reaction welding / thermite welding (see link: https: / / www.twi- electrodeposition, or optionally, by a combination of two or more of these processes.

[0014] All of the mentioned fusion methods are usable, but each will require its unique adaptation of the distance units used, which in each case is known to the skilled artisan within each art of fusing, however the wide range of fusion possibilities, reduced shadow effect and enhanced flexibility or spring action and distance unit placement on the sides of the bipolar plate offered by the singular distance units could not have been predicted without inventive effort. It is mentioned that a fusion zone at one end of a distance unit may well be provided with a fusing process which differs from the process used at an opposed end thereof. At one end of the distance units such as the end fused to the bipolar plate, an electrical resistance welding could be used, while at the opposed end, the electrode end of a distance unit the same or another fusion process may be used. In most cases, all distance units are fused at both ends, however it is possible to omit the fusing zone at one end for some of the distance units, as long as at least one end of a distance unit is fused to its adjacent electrode or bipolar plate. In most cases one and the same fusion technique will preferably be used for fusing all of the distance units at same ends thereof, but even this is not a requirement. Possibly centrally placed distance units on a bipolar plate may be fused using one of the mentioned technique while peripherally placed distance units may be fused to electrode or bipolar plate using a completely different technique.

[0015] [3] In a further embodiment, the fusion zones between singular distance units and the bipolar plate are adapted to be established on two opposed sides of the bipolar plate, either simultaneously from the two opposed sides, or unilaterally from one side at a time.

[0016] If the distance units are fused with the bipolar plate from opposed sides simultaneously, it is preferred that the distance units on the two sides of a bipolar plate are aligned, such that the pressurization force possibly required for the provision of the fusion zones at opposed sides may out-balance each other. If alignment of distance units sitting on opposed sides of a diaphragm in a stack build is desired, this may easily be accomplished with identically made bipolar plate and electrode assemblies, however if misalignment is desired, two versions of the bipolar plate and electrode assemblies may be required. If positioning of the individual distance units on each side of the bipolar plate is a numerically controlled process, such two different versions will be easy to manufacture.

[0017] [4] In an embodiment, the distance units comprise a thread, needle or mesh like first part extending between the bipolar plate and the electrode, where the thread, needle or mesh like first part has a bipolar plate-end welding foot like protrusion extending in a direction parallel to a bipolar plate plane and has an electrode-end further protrusion extending in a direction parallel to an electrode plane, when the distance units are mounted between electrode and bipolar plate.

[0018] The distance units thus are comprised of three segments:

[0019] 1 : a thread or needle like first part, which spans the distance between the bipolar plate and electrode and this first part shall both provide an electrical connection with high conductivity, and ideally will also provide some resilience to allow the electrode to be moved towards the bipolar plate and by itself, due to a spring effect of the thread, needle or mesh like part, resume its original position and sustain a spring-driven contact between a diaphragm of an electrolyser sell and the electrode therein during such a back and forth movement,

[0020] 2: a bipolar plate-end welding foot like protrusion at one end extending in a direction parallel to a bipolar plate plane, which bipolar plate-end welding foot like protrusion is adapted to be fused with the bipolar plate,

[0021] 3: an electrode-end further protrusion at an opposed end extending in a direction parallel to an electrode plane, and also this electrode-end further protrusion is adapted to be fused to an electrode surface which surface faces the bipolar plate. The two fusion zones must be corrosion resistant with respect to the electrolytes and production gasses and the fusion zones need to not be prone to hydrogen embrittlement. It is considered that nickel and nickel alloys will be usable for the bipolar plate, the distance units and electrodes in case the electrolyser in which a bipolar plate and electrodes assembly is to be used, is an alkaline water electrolyser, such as a pressurized alkaline electrolyser.

[0022] [5] In an embodiment of the invention at least some of the bipolar end welding foot like protrusions are fused to the bipolar plate, and at least some of the electrode-end further protrusions are fused with the electrode in such a way that all of the distance units arranged between a bipolar plate and an electrode are fused with at least one of either bipolar plate or electrode.

[0023] The fusion between a number of distance unit bipolar plate-end welding foot like protrusions and the bipolar plate may be accomplished in many different ways, and spot welding (also referred to as electrical resistance welding) is a natural chois given the high penetration of this process in many parts of metal working. Preferably a bipolar plate with an array of distance units on its two opposed sides is finalized prior to the addition of an electrode on each side thereof, and the formation of fusion zones between the respective electrode and the electrode-end further protrusions of the distance elements. The formation of fusion zones between the electrode-end further protrusion and an electrode may be made with a well-known laser welding technique, in which an electrode is pressed gently against the multitude of distance units, and whereafter heat in the shape of laser light is targeted onto the desired fusion zones from the far side of the electrode (the side facing away from the bipolar plate). A partial melt of the electrode and / or the electrode-end further protrusions at the fusion zones may result from this, and also, in case the electrode is a stretch metal plate, radiation will penetrate the openings in such a stretch metal plate, and result in heating of the surfaces of the electrode-end further protrusions causing a partial melt of this surface.

[0024] A chemical reaction or combustion welding technique may alternatively be employed, in which all of or a group of the electrode-end further protrusions of the array of distance units are welded to an electrode surface during a single welding operation. Solder and / or brazing operations as well as electroplating deposition operations are also usable to accomplish the formation of fusion zones between arrays of distance units on a bipolar plate and electrode-end further protrusions thereof and an electrode. As an example, nickel brazing may be accomplished in an oven and nickel braze material may be added to either or both of electrode ends of distance units and electrode connection points in any one of well-known methods.

[0025] It is naturally also possible to fuse the electrode-end further protrusion of distance units individually or in groups onto an electrode initially, to thereby finalize an assembly of electrode and distance units. Following this operation, all or at least some of the bipolar plate-end welding foot like protrusions of the distance units are fused onto the surface of a bipolar plate in a single operational step. This fusing operation may require a fusing technique other than resistance welding or laserwelding, and a technique such as chemical reaction welding or solder / braze techniques are better utilized to ensure such a multitude of fusion zones.

[0026] [6] In an embodiment the electrode is free of cathodic or anodic coating and / or surface modifications at any point where it is fused to a further element.

[0027] Any such coating or surface modification may be avoided using masking techniques in which patches of cover material is transferred onto the surface of a metal electrode by a method such as serigraphic or ink-jet printing in a fluid or semi-fluid conditions, and then hardened into a dense bodies of cover material, hereafter the electrode is treated and receives its active surface coating / modification, only leaving the masked-out areas free of the coating / surface modification, whereafter the masking material is removed. Masking materials such as nitril or similarly polymer material or materials which solidify by heat or light or by extraction of a solvent or emulsifier are obvious choices as masking materials.

[0028] Alternatively, abrasive or chemical removal of an electrolytically active surface coating / modification layer from the electrode surfaces are performed, in areas where a fusion with a distance unit part will be performed following a surface coating / modification operation.

[0029] [7] In an embodiment the thread, needle or mesh like first part of the distance unit is curved in a plane, or in a 3D shape, optionally along like curve having a cylindrical- , conical- or hour-glass circumscribe shape to allow the electrode movability towards and away from the bipolar plate.

[0030] Different curved shapes of a thread or needle like first part of a distance unit will leave it with a spring facility, provided its base material has an elastic deformation range, which is the case for most nickel compositions and Ni based alloys, at temperatures between 10 and 150 deg. Celsius. A well-known and well tested 3D shape to render a thread or needle like metal spring, is to shape it along a box spring curve. Here it is preferred that the circumscribe shape is cylindrical-, conical or hour-glass shaped and with a circular trace in planes parallel to the bipolar or electrode planes. The trace is here understood as the perpendicular projection of 360 deg. of spring continuous thread material onto either bipolar plate or electrode plane. An advantage of such a circular trace would also reside in the simplified version of the box spring generator to be used, as opposed to box spring generators adapted to generate more square- or starshaped traces whether or not they be with cylindrical, hour-glass or conical circumscribe shapes.

[0031] Alternatives to the box-spring like element are wavy springs, Chinese lamp like shapes or simple single-string wavy flat springs.

[0032] Wavy springs are optionally wound in the manner of box-springs, however, have perturbations in the axial direction of the spring along each winding such that each winding will touch adjoining windings at a multitude of places. The wavy spring has the advantage that it supplies an even pressure along the final windings to the bipolar plate and electrode respectively. The final winding in both ends of a wavy spring will comprise bipolar plate-end welding foot like protrusion and electrode-end further protrusion respectively and to this end be generally flat with a surface plane parallel to the bipolar plate and electrode planes. The last winding in both ends may be made with a widened metal strip to ensure welding foot and further projection for enhanced attachment to bipolar plate and electrode.

[0033] Chinese lamp like springs may have top and bottom flanges folded to extend in parallel with the bipolar plate which at one end may then function as welding foot for possible resistance welding onto the bipolar plate and at an opposed end, such flanges may serve as electrode-end further protrusion for welding to an electrode.

[0034] Simple single string wavy flat springs are simple single strips of flat metal, which are shaped with undulations in the space between the bipolar plate and the electrode. Such a strip of undulating flat metal may at either end comprise a part extending along and in parallel with the bipolar plate surface, which extension may then serve as welding foot. Alternatively, any bottom or valley part of the undulation, assuming that undulating piece of flat metal is resting on the bipolar plate and touching the bipolar plate upper surface with all downward directed undulation or wave wallies, may serve as a bipolar plate-end welding foot like protrusion for the formation of a fusion zone with the bipolar plate. Likewise, any wave top may serve as an electrode-end further protrusion for attachment to the electrode, such as by any of the mentioned attachment methods.

[0035] [8] In an embodiment, a box-spring like curve of the distance unit has the bipolar plate-end welding foot like protrusion and the electrode-end further protrusion provided as circular or spirally wound extensions of the thread or needle like first part.

[0036] Preferably the bipolar plate-end welding foot like protrusion which is adapted to be fused with the bipolar plate is provided in the shape of a spiral, where the further extension is provided in the shape of a circular last winding. The spiral shall ensure a very good welding foot towards the bipolar plate. If the spiral extends in a plane inwardly from a circumscribe shape, the distance unit may be added onto the exterior of a mandrel and if the spiral extends in a plane outwardly from a circumscribe shape, the distance unit may be added to a blind-hole of a mandrel, and in either case such a mandrel may be used for spotwelding or alternatively it may be used for friction welding of a distance unit onto a bipolar plate. The circular last winding which shall reside at the electrode, establishes a fusion area without occupying a lot of real estate on the electrode.

[0037] As mentioned above, a welding foot like protrusion may be provided at the electrode end of a distance unit and in this case all distance units are spot-welded to an electrode. An anode or cathode electrode having all of the distance units attached thereto may then be added to a bipolar plate, and fusion zones provided between the distance unit bipolar plate ends (possibly shaped with a further extension).

[0038] [9] The invention also comprise a method for generating a bipolar plate and electrodes assembly whereby one or more controlled generators of distance units are provided proximal to a bipolar plate or an electrode, at least one generator is energized to produce a distance unit while drawing material from a bobbin in a first move, and that in a second move either

[0039] I. the bipolar plate-end welding foot like protrusion of a generated distance unit is urged against the bipolar plate and is fused to the bipolar plate, or

[0040] II. an electrode-end further protrusion is urged against an electrode and fused to the electrode, and that in a third move arranged to take place prior to or after the fusion move, the generated distance unit is cut free from its respective bobbin.

[0041] When the distance unit is shaped as a box spring, these operations are simple, however the distance unit may be shaped as a multilayer or single layer wave spring, or alternatively may be shaped as a Chinese lamp like element, and the formation of the distance unit may comprise both stamping and / or other shaping operations, however these operations may well be performed on thread-like or flat strip material drawn from a bobbin and in the rate at which individual elements are shaped and fastened to the bipolar plate or electrode. Fusion to the bipolar plate or electrode may be performed by resistance welding.

[0010] In an embodiment of the method, the controlled generators of distance units are arranged along one or more radial lines with respect to the bipolar plate or electrode and the bipolar plate / electrode and lines with generators are rotated with respect to each other prior to the generation and fastening of a distance unit.

[0042] With this arrangement, it will be possible to arrange distance units in concentric circles on round bipolar plates or electrodes in a most speedy way.

[0043]

[0011] In an embodiment of the method, the controlled generators are arranged along parallel chord lines with respect to the bipolar plate / electrode, and the bipolar plate / electrode and chord line are translated transversely to the parallel chord lines with respect to each other prior to the generation and fastening of a distance unit.

[0044] With these provisions it will be possible to arrange and evenly disperse distance units on rectangular or irregularly shaped bipolar plates or electrodes in a speedy manner.

[0045]

[0012] In an embodiment of the method, the controlled generators are arranged along one or more straight axes and are each movable along said axes and at least one of the generators is / are moved along the axis prior to generating and fastening of a curved distance unit to a bipolar plate or electrode.

[0046] With these provisions, a vast multitude of patterns of dispersions of distance units across bipolar plates or electrodes becomes possible.

[0047]

[0013] In an embodiment of the method for generating a bipolar plate and electrode assembly, the electrode-end further protrusion of the distance unit is flattened in a plastic deformation or in an abrasive process, in a direction parallel to the electrode , and further optionally during this process, abrasiveness of the surface parts of the electrode-end further protrusion which are adapted to face the electrode, is provided. An abrasive upper surface (the surface adapted to face an electrode) may aid in cleaning a fusion area of the electrode and ensure naked metal to metal contact between the electrode and the distance unit. This may be done in a cleaning process whereby either: the electrode and a multitude of distance units fused to a bipolar plate are pressed gently against each other while the electrode is subject to vibrations optionally in its electrode plane. Optionally such vibrations are provided in the ultrasound domain to ensure actual but only minute movement between the surface parts of the electrode and a multitude of distance unit electrode end further protrusions to also ensure that only the actual footprint of the electrode end further protrusions receive abrasive impact from the vibrations, or each distance unit which is to be fused individually onto an electrode is vibrated prior to formation of a fusion zone, such as by spot welding. This may be done by vibrating a mandrel on which the distance unit resides prior to being welded to the electrode.

[0048]

[0014] In an embodiment of the method for generating a bipolar plate and electrode assembly a plastic deformation process or an abrasive process is used on the bipolar plate-end welding foot like protrusion to thereby flatten or make the bipolar plate-end welding foot like protrusion pointy.

[0049] Either the bipolar plate-end welding foot like protrusion or the electrode end further protrusion is used in a welding process such as a resistance welding process to fuse the bipolar plate-end welding foot like protrusion to the bipolar plate or to fuse the electrode end further protrusion to the electrode at a predetermined position, and for a resistance welding process to work optimally, the welding foot like protrusion or the electrode end further protrusion is shaped according to the needs of the welding process.

[0050]

[0015] In an embodiment of the method for generating a bipolar plate and electrode assembly, the electrode-end further protrusion of all distance units mounted on a first or second side of a bipolar plate are welded to an electrode by laser welding optionally by feeding the laser radiation through a holding plate, such as a plate with through-holes at welding sites, alternatively a transparent plate, preferably with high transparency at a welding laser radiation frequency, such as a glass plate whereby the holding plate is adapted to add a predefined compression force to a surface of the electrode during the welding process.

[0051] The holding pressure is dimensioned to ensure a high probability of a contact between each welding surface of the distance units and the electrode, such that the welding will actually take place, and will take place without larger deformation of the parts being welded to each other. Further, the pressure plate may work to cool down the surroundings of the welding zone, especially areas of the electrode which surrounds the welding zones, such that the welding heat does not injures possible surface modifications or added layers during the welding process.

[0052] Not all distance units shall necessarily be welded at both ends. It will be a choice whether to weld some distance units at both ends as some can be free at the electrode or at the bipolar plate end. Such free ends will get contact to the electrode / bi polar plate anyway due to initial compression during assembly of a stack bipolar plates and electrode assemblies and diaphragms. Particularly, it is preferred not to weld long wavy springs on both electrode and bipolar plate sides, as such a welding would hamper their movement and thus spring like function. It should be emphasised that the electrode is usually an open structure, such as a stretch metal plate and laser energy may heat both electrode and the welding surface of a distance unit simultaneously from a far side of an electrode (side facing away from the bipolar plate to which the electrode is attached or adapted to be attached to).

[0053]

[0016] In an embodiment of the method for generating a bipolar plate and electrode assembly, the electrode-end further protrusions of all or some of the distance units mounted on a predefined side of a bipolar plate are welded to an electrode by chemical reaction and / or combustion welding in a simultaneous welding action.

[0054] Such a welding action may be very speedy and ensure a very uniform fusion zone between individual electrode-end further protrusions of the distance units. Preferably also in this kind of welding, a pressure plate or grid is used to ensure contact between all electrode- end further protrusions and the electrode by slightly pressurizing the electrode in the direction of the bipolar plate. Us of a grid for this purpose will allow gasses possibly being produced by the combustion welding to escape from the welding zone without causing high gas speeds, which otherwise might cause disturbances of welding actions taking place downstream of such gas streams. A plate however may be instrumental in securing some cooling of close to welding zone areas of the electrode.

[0055]

[0017] In an embodiment the bipolar plate end welding foot like protrusion of some or all distance units mounted onto an electrode are welded to the bipolar plate by chemical reaction and / or combustion welding in a simultaneous welding action.

[0056] As mentioned above, an initial step of mounting of distance units may take place onto an electrode or onto a bipolar plate. If the initial mounting is onto an electrode, there will be a need to provide fusion zones between a multitude of distance unit bipolar plate end welding foot like protrusions and a bipolar plate. This is not altogether easy, but a solder or brazing technique may be applied or a chemical reaction and / or combustion welding technique may be employed to achieve simultaneous fusion zones of all or a multitude of bipolar plate end welding foot protrusions and a bipolar plate. Possibly such an operation may take place on both sides of a bipolar plate simultaneously, which especially for a solder or brazing technique is preferred, as here the bipolar plate would most likely need to be heated up to or slightly above a melting temperature of a used solder. If a chemical reaction welding is used, it may be possible to carry out welding at first one side and then at the opposed side of a bipolar plate as heating may here be concentrated to the welding zones such that the fusion zones at a first side of a bipolar plate are not detached during the generation of fusion zones at an opposed side.

[0057]

[0018] In an embodiment of the method for generating a bipolar plate and electrode assembly, prior to any welding process between the electrode-end further protrusion and an electrode, the electrode is simultaneously pressed towards the electrode-end further protrusions and vibrated with respect to the electrode-end further protrusions, such as by vibrating the electrode. In case this vibration step is to be utilized in conjunction with the combustion welding process, it will have to be undertaken in a separate action prior to the addition of the combustible medium responsible for the combustion welding step.

[0058]

[0019] The invention also regards an electrolyser adapted for electrolysing water into oxygen and hydrogen, and comprising a cell stack having alternatingly a diaphragm and a bipolar plate and electrode assembly whereby the assembly is comprised of a number of singular distance units interposed between and interconnecting bipolar plate and respective cathode and anode electrode, which distance units are adapted to be generated by way of one or more distance unit controlled generators during an assembly and fusion process.

[0059] In such an electrolyser, there will be a very well controlled pressurization force onto the diaphragms from each of neighbouring electrodes and this will result in a more uniform zero gap relationship between diaphragm and the two electrodes on the two sides thereof. Further, having the distance units provided as singular units during manufacture and not provided as an integral part of a bipolar plate allows for easy and speedy re-design of the distance units. In this connection it also is easier to scale electrolyser units such as providing larger or smaller electrolyser units.

[0060] It should be emphasized that the term "comprises / comprising / comprised of" when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0061] Brief description of the drawings

[0062] In the following, the invention will be described in greater detail with reference to embodiments shown by the enclosed figures. It should be emphasized that the embodiments shown are used for example purposes only and should not be used to limit the scope of the invention.

[0063] Figure 1 is a schematic representation of a section through an electrolyser cell with two differently shaped distance units 3, Fig. 2 shows a schematic representation of the various flow channels and process chambers in a stack build,

[0064] Fig. 3 shows a cross sectional side view of prior art bipolar plate with integrate distance units 3,

[0065] Fig. 4 shows an enlarged section through a prior art distance unit 3,

[0066] Fig. 5 is a schematic representation of a coiling- and welding unit above a bipolar plate,

[0067] Fig. 6 is a 3D representation in sectional view of a welding mandrel with a spring thereon in a welding position,

[0068] Fig. 7 is a 3D representation of a further embodiment of an embodiment of the distance unit 3,

[0069] Fig. 8 is a 3D representation of yet a further embodiment of the distance unit 3,

[0070] Fig. 9 is a 3D representation of an hour-glass shaped distance unit 3,

[0071] Fig. 10 is a 3D representation of a box-spring like distance unit 3,

[0072] Fig. 11 is a 3D representation of a wave-shaped distance unit and

[0073] Fig. 12 shows holding plate 33 used in a welding operation.

[0074] Detailed description of the embodiments

[0075] It is to be noted that the figures and the above description have shown the example embodiments in a simple and schematic manner. Many of the specific mechanical details have not been shown since the person skilled in the art should be familiar with these details and they would just unnecessarily complicate this description. For example, the specific materials used, and the specific shaping procedure have not been described in detail since it is maintained that the person skilled in the art would be able to find suitable materials and suitable processes to manufacture the assembly according to the current invention.

[0076] A prior art bipolar plate and electrodes assembly is shown schematically in a sectional view in Fig. 3. The prior art bipolar plates 1.1 are customarily made with a circular circumference, however, may well be made as squares or rectangles in dependency of the kind of electrolyser plant in which they are to function. In Fig. 3 an edge part 21 of the prior art bipolar plate 1.1 and electrodes 2;26;27 are shown in an enlarged view in the circular close-up. The edge part 21 extends a bit beyond the extend of the two electrodes and no distance units or protrusions are allowed on the bipolar plate adjacent to the edge part 21, as this part shall be sealed to an inner periphery (not shown) of a cell stack frame member as well known in the art.

[0077] In Fig. 4 a protrusion of a prior art bipolar plate and electrodes assembly of the kind shown in Fig. 3 is shown here in sectional and enlarged view. As is clear from Figs. 3 and 4, the protrusion 18 will leave a corresponding indent 22 on its opposite side of the bipolar plate 1.1 as the protrusion 18 is shaped by the formation of an indent or “bump” in the bipolar plate. A protrusion cannot then be provided by any known reasonable deformation of the bipolar plate at the site of the corresponding indent 22 opposite the bump or protrusion 18. At the protrusion fusion zone 19 of a prior art bipolar plate 1.1 , a flat top part of the protrusion 18 is provided as seen clearly in Fig. 4, and when a prior art bipolar plate 1.1 and electrode assembly as shown in Fig. 3 is pressed against a diaphragm 30 (indicated schematically in Fig. 4), the flat top part 20 of the protrusion 18 will hamper the respective electrolyte 24; 25 from reaching the parts of the electrode 27; 2 residing between the flat top 20 and the diaphragm 30, and also any produced gasses will find it hard to escape this area. This effect is referred to as “shadow” effect of the protrusion or bump 18, and thus, a reduction in gas production is likely to be caused by this shadow effect, and no ready to implement solution to this problem is known in the prior art.

[0078] In Fig. 1 a single cell with a bipolar plate 1 and electrodes assembly 2; 26; 27 according to the invention is disclosed. Between electrodes 2 and corresponding bipolar plate 1 two different singular distance units 3 are disclosed. The distance units 3 are singular in the sense, that they are produced separately and then individually or in groups attached to the bipolar plate 1 through individual fusion zones 4 between each distance unit and a bipolar plate. The fusion zone 4 shall ensure good mechanical resistance and a low ohmic resistance between bipolar plate 1 and distance unit 3. The electric current which is to power each electrode 26;27 shall pass between the bipolar plate and the electrode through the distance units and any significant loss of power due to electric resistance between the bipolar plate and an electrode will lead to energy losses and corresponding generation of heat, which is un- desirable. The electric current shall also have to pass directly to / from the one electrode 26 to / from the other electrode 27 in a cell 28 and here propagate through the diaphragm 30. To this end the diaphragm 30 is permeable to ions and / or electrons however, any distance between the electrodes 2 in a cell 28 as well as the thickness of the diaphragm 30 will lead to resistive losses and is to be prevented. Thus, it is preferred that the anode electrode 26 and the cathode 27 in a cell 28 are urged gently against the diaphragm 30 from each side thereof.

[0079] It has recently been theorized that a controlled and well-defined small gap between electrode surface and diaphragm, may reduce the so-named cross over. Cross over results from dissolved gasses passing through the diaphragm, such that small amounts of hydrogen ventures from the cathode side of a diaphragm and into the adjacent anode side. And vice-versa, generated oxygen ventures from the anode side and through the diaphragm as dissolved gas and into the adjacent coathodic chamber. Measures, such as distance units inserted between the electrode and diaphragm is expected to counter this effect, and to ensure a uniform distance between electrode and diaphragm throughout each cell comprising such distance units, a gentle and controlled pressure force between diaphragm and electrodes on each side of the diaphragm is desired, and use of spring elements between electrode and bipolar plate on each side thereof may be instrumental in ensuring this force.

[0080] The fusion zone 4, between the bipolar plate 1 and the distance units 3, may be provided as a welding, a solder-connection or any other metal working interconnect fusion zone. If a welding zone is established, well known methods of welding, such as resistance or spot welding, laser welding, friction welding or even combustion- or chemical reaction welding may be suggested. In a friction welding process, a distance unit 3 is rotated around its length axis 29 and simultaneously pressured or forced against the bipolar plate whereby the friction between the distance unit and the bipolar plate will lead to heat generation and eventually one or both of the metal compositions of bipolar plate and distance unit will reach the melting point at which time the rotation may be stopped. This is preferably done one by one with each of the distance units. In the disclosed example, all distance units are initially added to the bipolar plate, but it is possible to initially add the distance units to the electrode one by one or a few at the time, and then in a separate procedure weld a multitude of distance units already seated on an electrode onto a surface of a bipolar plate.

[0081] Laser welding and spot welding are well known methods of welding in metal works and shall not be further commented, however it is to be mentioned that spot- or electrical resistance welding if used will allow all distance units or at least an array of distance units to be welded to the bipolar plate or an electrode in a simultaneous welding action, and this may be preferred. Also, this kind of welding may allow welding from two opposed sides of a bipolar plate to take place simultaneously in cases where distance units are initially added to the bipolar plate.

[0082] In an actual electrolyser, it is preferred to have only one kind of distance units throughout all cells, however it is an option to include differently shaped units as disclosed in Fig. 1. Such differently shaped units may be used as fluid flow guides in individual cells and may thus further improve cell performance.

[0083] Combustion- or chemical reaction welding could be used here. In this process substances which will react or combust in a highly exothermic process is / are added to the surface or surfaces which are to be united in a fusion or welding zone. Following this, the surfaces are urged against each other, and the chemical substances are caused to combust or react, leading to heat generation and formation of a short lived melting zone between the parts which result in a welding between the two parts. The process may allow all of the distance units on one side of the bipolar plate or the surface of an electrode to be fused to the plate / electrode in a single operational step, whereby initially fastening cites on the bipolar plate / electrode and / or the distance units fusing areas are pre-prepared with a combustible substance such as fine metal powder, and then placed in the presence of an oxygen rich atmosphere or an added oxygenator, whereafter the metal powder is ignited using an external energy source such as a pressure wave, heat, laser radiation, or other sorts of radiation or friction / vibrations between the parts to be fused. An oxygenator may preferably be added to the surfaces opposing the surfaces enriched with metal powder or other highly combustible material. The process may work at one side alone or both sides of the bipolar plate simultaneously.

[0084] It should be mentioned that the purpose of the fusion zone is to provide a corrosion resistant and durable electrically conducting connection between the distance units and the bipolar plate and also fusion zones between electrodes and distance units are to serve this purpose. Further, a mechanical connection is desired, however after an assembly of an electrolyser stack, it is expected that a constant pressure between the distance units and the bipolar plates will be maintained throughout the lifetime of the electrolyser, and thus only relatively small mechanical stresses are to be expected in the fusion zones.

[0085] The distance units 3 shown in Fig. 1 are shaped as a box-spring like elements. Two different circumscribe shapes are shown: a cylindrical circumscribe shape 12 and an hourglass circumscribe shape 11. Many other box-spring like shapes are possible and the two shapes are just shown as indicators of the larger design options provided here. A circular circumscribe shape with an axis running perpendicular to the bipolar plate and electrode planes is indicated however, other than circular shapes are possible, such as oval, square or even starshaped circumscribe shapes are possible options. The actual connection is provided by the needle or thread like first part 5 of the box-spring like shaped element extending between the bipolar plate 1 and the electrode 2. The thread or needle like element 5 may be shaped as seen in Fig. 1 , Fig. 2 and Figs. 9 and 10 with a number of windings of a spring-like element, but the thread or needle like first part 5 may also extend along the circumscribe surface, but comprise only one winding, or even only a fraction of a winding, such as one half or one quarter of a winding, and thus look more like an s- shaped element. In any of these cases, the thread or needle like first part 5 shall have a bipolar plate-end welding foot like protrusion 6 extending parallel to the bipolar plate 1. In Fig. 1 , the bipolar plate-end welding foot like protrusions 6 is shaped as a spirally wound extension 13 of the box-spring shaped thread or needle like first part 5. Such a flat spirally wound extension 13 of the box spring shaped thread or needle like first part 5 may also be wound externally of a circumscribe shape of the box-spring provided between bipolar plate and the electrode, which could make welding, especially spot or resistance welding particularly easy.

[0086] The thread or needle like first part 5 shall have an electrode-end further protrusion 9, which extends parallel to an electrode, and is adapted for fusion with the electrode. In the example seen in Fig. 1, the electrode-end further protrusion 9 is shaped as a circular wound extension 14. The circular wound extension 14 allows the centre of the circular extension 14 at a fusion zone 8 to remain free from contact with the distance unit 3, and open for exchange of fluid and gasses with the remaining part of the half-cell chamber in which it will be placed during use. Further, the open structure of the box-spring like distance unit 3 shall allow gasses and fluids 24, 25 to pass in a direction parallel to the bipolar plate, and only comprise a marginal fluid flow resistance to this passage. As seen in Fig. 1 and Fig. 2, the bipolar plate 1 and the electrodes at either side thereof are all arranged in parallel in this embodiment, however a non-parallel arrangement between electrode and bipolar plate is possible and this would require the thread like first part 5 of distance units to vary in length according to their placement on a bipolar plate.

[0087] The electrode 2 is a cathode electrode 27 when residing in a cathodic part of a halfcell which shall be filled with a catholyte 25 and when energized the cathode electrode 27 shall evolve hydrogen from the water in the catholyte fluid. The electrode 2 is an anode electrode 26 when residing in an anodic part of a half-cell which shall be filled with an anolyte 24 and when energized the anode electrode 26 shall evolve oxygen from the water in the anolyte fluid. The two half-cells are separated from each other by a diaphragm 30, adapted to ensure, that the formed gasses in each half-cell remain separated from each other as far as possible. In Fig. 1 electrode fusion zones 8 are indicated between the two electrodes 25, 26 and the respective electrode-end further protrusions 9 of the distance units 3. These fusion zones may be small and take up very little area on the respective electrode 25, 26. The fusion zones 8 may be generated by laser welding, by combustion- or chemical reaction welding, by electrodeposition by soldering / bracing, by friction welding, by electron beam welding or by any other known fusion technique. The electrodes 2 are customarily made from perforated sheets of metal such as stretch metal and thus represents a flat but nevertheless 3-dimensional structure. Laser welding take some adjustments of energy levels and other process parameters, however, will represent a workable way to the provision of electrode and distance unit fusion zones 8. Also, the option of fusion by combustion- or chemical reaction may be used as well as may fusion by chemical or electrochemical deposition or by solder- or brazing techniques. These fusion options offer the up-side of a process wherein all electrode to distance units connections to a given electrode and / or a given bipolar plate surface are generated simultaneously, however may not necessarily work with all possible anolytic or catholytic coatings or surface modifications often used on electrodes. It is however an option to provide the fusion between distance units and electrodes 2; 26, 27 prior to the treatment of the electrode to generate analytically or catholytically active surfaces.

[0088] Preferably, any welding or soldering onto an electrode is only carried out on an electrode site where no catalytic or anolytic layer and or surface modifications resides on the electrode surface. Any such coating / surface modification may to this end be made with the provision of blanking out or masking off the connection sites on the electrode, or alternatively the connection sites are cleaned mechanically such as by abrasion or using a chemical agent to leave a local naked metal surface ideal for welding, soldering or other fusing. Several masking techniques are available, and preferably a masking material such as nitril or latex or like polymer-based compound may be employed and applied in conventional manner such as by serigraphic or screenprint techniques, or by inkjet printing. When the catholytic / anolytic layers or surface modifications are applied to the electrode, the masked-out areas will remain naked and un-affected by the application of the layers / surface modifications, and the masking material may be either dissolved or removed by being cooled down to a temperature, where the polymer becomes brittle and may be more easily removed mechanically.

[0089] A further way of ensuring a metal-to-metal connection between the electrode and an electrode-end further protrusion 9 is to gently press an electrode towards an array of distance unit electrode-end further protrusions, and then vibrate the electrode with respect to the electrode-end further protrusions. Especially if an abrasive surface was generated on the part of the electrode-end further protrusion, adapted to be fused with the electrode, this procedure will help to remove surface deposits / modifications from the electrode surface. Surface deposits may be in the form of intentionally generated surface modifications or coatings or may be layers of corrosion or the like residing on the electrode.

[0090] Certain catalytically or anolytically active elements used in coatings of electrodes which are employed in electrolysers are temperature sensitive, which may lead to injury of larger surface parts of an electrode during a welding operation. The welding process based on exothermic chemical reactions directly on surface elements lends itself handily in ensuring both a secure welding operation while at the same time keeping the heat generation needed very local and focused on the welding cite. It is also possible to actively cool down the side of an electrode facing away from the distance units, such as by pressing a cooling plate or the like heat sink onto the electrode during a combustion or chemical reaction welding to thereby ensure that heat is not dissipated into wider areas of an electrode remote to the actual cites where welding is desired. Provided that the welding or fusion cites on electrodes are naked and with no coating / surface modification, the electrode may also, prior to a welding operation, be soaked in a cooling medium, which may adhere to a coating layer / modified surface, such as a porous surface part, but will not be present at naked welding cites with little or no porosity, in which case the cooling medium may evaporate during a welding operation and keep the electrode generally at reduced temperature, even if welding is taking place adjacent to cites comprising surface coating or modifications. The cooling medium could be a gas or preferably a liquid such as water. In the schematic representation of a cell stack in Fig. 2 only one box spring like distance unit is shown in each half-cell, however in a real-life situation, a multitude of such springs will be provided between adjacent electrode / bipolar plate pairs.

[0091] Distance elements may be centered with respect to each other on opposed sides of a bipolar plate as shown in Fig. 2 or may be off-centre with respect to each other on the opposed sides of the bipolar plate 1. Cell stack internal inflow manifolds 36 for anolyte and stack internal outflow manifold for anolyte and oxygen gas 36.1 are schematically shown, and likewise cell stack internal manifold 37 for catholyte and stack internal outflow manifold 37.2 for catholyte and hydrogen gas are schematically shown. The range of cells 28 with manifold flow channels 36; 36.1 ; 37; 37.1 are usually termed a cell stack 38. Often endplates, current injectors and possible pressure containing parts arranged externally of the cells are considered part of the stack 38, even if not disclosed in Fig. 2.

[0092] Usually, the diaphragms 30 which are arranged to keep the gasses in the two half cells of a cell 28 apart from each other, are made from a polymer substance, however it is known that certain ceramic materials may also be used for this purpose. In this case, it is important that box-spring distance units 3.1 on each side of the diaphragm are aligned with each other, not just with respect to the centre axis of the box-spring like elements, but also rotation wise, as the size of the pressure forces transmitted through the two electrodes and onto two opposed sides of a diaphragm may be larger at an intersection point between the thread or needle like first part 5 of a distance unit 3 and its electrode-end further protrusion 9, than at any other point of an electrode-end further protrusion 9 being welded to an electrode. The brittle nature of a ceramic material membrane mandates, that the forces it is subject to, from two opposed sides are well aligned. The ability to freely position the distance units on two sides of a bipolar plate will make any such constraints easier to fulfil with the distance units according to the invention than with prior art distance units of bump-like protrusionsl 8; 22 made in the bipolar plate 1.1.

[0093] Box springs 3.1 and other types of smaller springs have been produced in frog abundance throughout the latest century and there is a robust and well-established industry around facilitating continued production of springs of many kinds. Among others, there are a range of machines and machine makers focusing on speed and reliability as well as versatility in generating a series of alike box-springs from a metal thread product drawn off a bobbin 23.

[0094] In the following description, it is assumed that individual distance units are fused with the bipolar plate to begin with, and that following the establishment of an array of distance units on a bipolar plate, an electrode is added to and fused with electrode end further protrusions of such an array. However, it is just as well possible to add an array of distance units, such as one by one or in groups onto the surface of an electrode and fuse the electrode end further protrusions thereof to the electrode. Such an assembly of a multitude of distance units fused to an electrode surface may then be pressed towards a bipolar plate surface and bipolar plate ends of distance units may then, one by one, or altogether simultaneously be fused to the bipolar plate.

[0095] According to the invention one or more controlled generators 15 of box springs 3.1 or other distance units 3 are provided proximal to a bipolar plate 1, or alternatively proximal to an electrode (not shown).

[0096] The bipolar plate option is schematically illustrated in Fig. 5. In a first move, one or more generators 15 are energized to produce a box-spring like distance unit 3 while drawing thread like material for the spring from a bobbin 23. In one embodiment, the distance unit 3 is produced directly onto a spot-welding (resistance-welding) mandrel 34 seen in Fig. 6, and the mandrel 34, optionally along with the controlled generator 15 is displaced towards the bipolar plate 1, where, in a second move it is urged towards the bipolar plate 1 having the bipolar plate-end welding foot like protrusion 6 of the distance unit 3 placed at a free end part thereof. This end part shall thus urge the bipolar plate-end welding foot like protrusion 6 towards the bipolar plate 1, and the welding current is supplied to the mandrel 34 (and / or bipolar plate) in a third move. A further move will be to cut the produced box spring like distance unit 3 free from the bobbin 23, and this move may take place prior to or after a welding process.

[0097] In a slightly different procedure, the transfer and the welding operation is performed by a separately moving spot-welding unit 32. Here, the distance unit 3 exits the controlled generator 15 during its production, and is transferred onto the mandrel 34, and cut away from the connection to the bobbin 23. Now the mandrel with the distance unit in place thereon is turned towards the bipolar plate 1, and the welding unit 32 is moved with the mandrel whereby the mandrel 34 is urged towards the bipolar plate 1, and a spotwelding operation may take place. If two or more mandrels 34 are provided, one mandrel may be equipped with a distance unit exiting the controlled generator 15, while another mandrel 34 with a distance unit in place is adapted to perform the welding operation. The mandrel 34 is here described as a spot-welding or resistance welding part but it would also be an option alternatively to use a friction welding technique for the generation of a fusion zone between the distance unit 3 and bipolar plate 1.

[0098] Once a welding operation has been performed, the bipolar plate 1 and the generator 15 along with its spot-welding unit 32 / friction welding units are moved with respect to one another to a new location with respect to the bipolar plate 1. An array of controlled generators 15 and spot-welding units 32 may be provided, such as along one or more lines and the spot-welding units 32 may be movable with respect to each other along each line. Also, such an array of distance unit providers 15 may be aligned along a diameter or along a chord line of a bipolar plate 1 whereby the bipolar plate 1 may either translate or rotate with respect to such an array of distance unit providers 15 between individual spot-welding operations.

[0099] Various distance unit shapes, which are all flexible and allows flow of electrolyte and produced gasses at the electrode, are suggested.

[0100] One such distance unit shape is the wavy spring 3.2 shown in Fig. 7. The wavy spring unit 3.2 is comprised of a cylindrically shaped metal coil, with distance between individual coil turns, wherein further, each coil turn is shaped to undulate axially (in the direction of the cylindrical axis) along its turn, such that undulations in opposite axial directions touch each other in adjacent turns. The wavy spring 3.2 has the advantage that due to the multiple points of touch between consecutive turns, the spring pressure on a bipolar plate or electrode will distribute evenly along a last turn. This is also an advantage if the wavy spring is used between bipolar plate and electrode, especially if diaphragms comprised of ceramic material is employed in a stack build for water electrolysis.

[0101] A further distance unit variant is a Chinese lamp like shape 3.3 shown in Fig. 8 in a 3D projection. Here, two cylindrical tube-like structures 3.3.1 are axially aligned and interconnected by curved strands of material 3.3.2 while the cylindrical tube-like structures 3.3.1 are fused at end flanges thereof to bipolar plate 1 and electrode 2 respectively. The basic shape may be stamped out from flat metal band in a first action (not shown) which also stamps out material to leave the strands of material which interconnects the parts adapted to form the two cylindrical tube-like structures 3.3.1. In a second action the blanks may be rolled up to form the two cylindrical parts 3.3.1 and the intermediate strands, as the two cylindrical parts 3.3.1 are moved towards each other to impart a curvature to the intermediate strands of material 3.3.2. In further move, the Chinese lamp shaped distance unit is welded to one of a bipolar plate or to an electrode. In this further move, it may be an advantage to fold down, either inwards towards the centre axis or outward away from the centre axis, a flange element which will work as a welding foot protrusion, whereby such actions are well known from tin-making machinery. In a last action a bipolar plate or an electrode, whichever is missing, is welded onto all the units fastened to an electrode / bipolar plate in the named further move. It is noticed that the strands of material 3.3.2 shown in Fig. 8 are one out of a multitude of cuts in a possible blank adapted to make up the Chinese lamp shape, which will provide both a fluid flow through option and a spring like effect between the two cylindrical tubelike structures 3.3.1. The strands 3.3.1 may be made to follow a spiral path between the two cylindrical tube-like structures and followingly provide something like a boxspring having a multitude of coils running in parallel. Also, it is possible to impart a stretch metal cut-pattern on a blank between the two to be folded cylindrical tubelike structures 3.3.1 , and then stretch the two structures away from each other to make a stretch metal middle part, and then fold the Chinese lamp shape, which will comprise the two cylindrical tube-like structures having an open and thus springy stretch metal middle part.

[0102] In Fig. 9 a distance unit 3 is disclosed in a 3D projection in its placement between a bipolar plate 1 and an electrode 2. The shown distance unit shape 3.1 has an hourglass outer circumscribe shape and compares to the shape seen in Fig. 1 , upper right and lower left part. Likewise, Fig. 10 discloses a box spring like distance unit 3, wherein the circumscribe shape is circular cylindrical. In both the Fig. 9 and Fig. 10 embodiments, there is an inwardly directed welding foot spirally wound projection, and naturally an outwardly directed spirally wound projection would be possible. In case such a spirally wound projection is outwardly directed, the welding foot shown in Fig. 6 shall be made with a cavity for accepting the cylindrical / hourglass shaped part of a distance unit and have a lower outwardly directed flange adapted to force the outwardly directed spirally wound projection towards a bipolar plate or electrode.

[0103] Fig. 11 shows a further spring shape, where a flat metal band has been undulated to a wavy shape 3.4 along its length axis and placed between the bipolar plate 1 and the electrode 2. The lowermost and uppermost parts of the undulations may serve as fusion zones with bipolar plate and electrode; and possibly only a central neighbouring set of uppermost and lowermost part of an undulation serves as fusion zones, which leave the remaining point of contact with the bipolar plate and electrode free to move along the plane of the bipolar plate and electrode towards and away from the fused centrally neighbouring set of undulations.

[0104] The prior art bipolar plate 1.1 shown in Fig. 3 has an area of around 0,3 m2and the number of bipolar plate protrusions 18 towards one side thereof is 114. If box spring distance units 3.1 were used instead of the protrusions 18, it will be straight forward to calculate the ohmic resistance in the springs between the bipolar plate and the electrode.

[0105] Assuming that the springs are made with 7 windings, are made with a circumscribe diameter of 15 mm, and are made from a 0,2 mm wire, the total ohmic resistance is below 0,35 ohm. This will only invoke minor ohmic losses at a current density of 1000mA / cm In this calculation it has been assumed, that there are only negligible ohmic losses in the fusion zones between the individual springs and bipolar plat / electrode, which is a fair assumption with the use of fusion zones based on the disclosed welding or solder techniques. List of parts

[0106] 1 Bipolar plate

[0107] 1.1 Prior art bipolar plate

[0108] 2 Electrode

[0109] 3 Distance unit

[0110] 3.1 Box spring

[0111] 3.2 Wavy spring

[0112] 3.3 Chinese lamp

[0113] 3.3.1 Tube like structures

[0114] 3.3.2 Curved strands of material

[0115] 3.4 Flat wave

[0116] 4 Fusion zone

[0117] 5 Thread or needle like first part

[0118] 6 Bipolar plate-end welding foot like protrusion

[0119] 7 Bipolar plate and electrodes assembly

[0120] 8 Electrode fusion zone

[0121] 9 Electrode-end further protrusion

[0122] 10 Anode or cathode coating / surface modification

[0123] 11 Hourglass circumscribe shape

[0124] 12 Cylindrical circumscribe shape

[0125] 13 Spirally wound extension

[0126] 14 Circular wound extension

[0127] 15 Generators of distance units

[0128] 16 Coil distance unit material thickness

[0129] 17 Chord line

[0130] 18 Bipolar plate protrusion

[0131] 19 Protrusion fusion zone

[0132] 20 Shadow zone

[0133] 21 Edge part of the prior art bipolar plate

[0134] 22 Corresponding indent

[0135] 23 Bobbin

[0136] 24 Anolyte

[0137] 25 Catholyte

[0138] 26 Anode electrode

[0139] 27 Cathode electrode

[0140] 28 Single cell

[0141] 29 Distance unit length axis

[0142] 30 Diaphragm

[0143] 32 Spot welding unit

[0144] 33 Holding plate

[0145] 34 Spot welding mandrel

[0146] 36 Stack internal inflow manifold for anolyte

[0147] 36.1 Stack internal outflow manifold for anolyte and oxygen

[0148] 37 Stack internal inflow manifold for catholyte

[0149] 37.1 Stack internal outflow manifold for catholyte and hydrogen

[0150] 38 Cell stack

Claims

Claims1. Bipolar plate (1) and electrodes (2; 26; 27) assembly whereby a bipolar plate (1) is connected to an electrode (2; 26; 27) through a number of distance units (3), characterised in that the distance unites (3) are singular, and that between each singular distance unit (3) and at least one of the bipolar plate and the electrode a fusion zone (4;8) is / are provided.

2. The bipolar plate (1) and electrode assembly according to claim 1 , characterised in that the fusion zone (4;8) is adapted to be established via resistance or spot welding, laser welding, electron beam welding, friction welding, combustion- or chemical reaction welding, by brazing and / or soldering or by electrodeposition, or optionally by a combination of two or more of any of these processes.

3. The bipolar plate (1) and electrode assembly according to claim 2, characterised in that fusion zones (4) between singular distance units (3) and the bipolar plate (1) are adapted to be established on two opposed sides of the bipolar plate, either simultaneously from the two opposed sides, or unilaterally from one side at a time.

4. The bipolar plate (1) and electrode assembly according to claim, 3 characterised in that, the distance units (3) comprise a thread, needle or mesh like first part (5) extending between the bipolar plate (1) and the electrode (2;26;27), where the thread, needle or mesh like first part (5) has a bipolar plate-end welding foot like protrusion (6) extending in a direction parallel to a bipolar plate (1) plane, and has an electrode-end further protrusion (9) extending in a direction parallel to an electrode (2;26;27) plane when the distance units (3) are mounted between electrode and bipolar plate (1).

5. The bipolar plate and electrode assembly according to claim 4, characterised in that at least some of the bipolar end welding foot like protrusions (6) are fused to the bipolar plate (1), and that at least some of the electrode-end further protrusions (9) are fused with the electrode (2) in such a way that all of the distance units arranged between a bipolar plate and an electrode are fused with at least one of either bipolar plate or electrode.

6. The bipolar plate and electrode assembly according to any one of the above claims, characterised in that the electrode (2;26;27), at any point where it is fused to a further element, is free of cathodic or anodic coati ng / surf ace modification.

7. The bipolar plate and electrode assembly according to claim 6, characterised in that, the thread, needle or mesh like first part (5) of the distance unit (3) is curved in a plane, or in a 3D shape, optionally along a box-spring like curve having a cylindrical- (12), conical- or hour-glass (11) circumscribe shape (11 ; 12), to allow the electrode (2;26;27) movability towards and away from the bipolar plate (1).

8. The bipolar plate and electrode assembly according to claim 7, characterised in that the box-spring like curve of the distance unit has the bipolar plate-end welding foot end protrusion (6) and the electrode-end further protrusion (9) provided as circular (14) or spirally wound extensions (13) of the tread or needle like first part (5).

9. A method for generating a bipolar plate and electrodes assembly (7) according to any one of claims 1 - 8, characterised in that, one or more controlled generators (15) of curved distance units (3) are provided proximal to a bipolar plate (1) or an electrode (2,26,27), at least one generator (15) is energized to produce a curved distance unit (3) while drawing material from a bobbin (23) in a first move, and that in a second move eitherI. a welding foot like protrusion (6) of a generated curved distance unit (3) is urged against a bipolar plate (1), and is fused to the bipolar plate (1), orII. an electrode-end further protrusion (9) is urged against an electrode and fused to the electrode, and that in a further move arranged to take place prior to or after the fusion move, the generated curved distance unit (3) is cut free from its respective bobbin (23).

10. The method for generating a bipolar plate and electrodes assembly (7) according to claim 9, characterised in that the controlled generator or generators (15) is / are arranged along one or more radial lines and theI. bipolar plate (1) or the electrode (2; 26; 27) andII. the lines with the generators (15) are rotated with respect to each other prior to the generation and fastening of a curved distance unit (3).

11. The method for generating a bipolar plate and electrode assembly (7) according to claim 9, characterised in that the controlled generators (15) are arranged along parallel chord lines with respect to the bipolar plate or the electrode (2; 26; 27), and theI. bipolar plate (1) or the electrode (2; 26; 27) andII. chord lines with the generators (15) are translated transversely to the parallel chord lines with respect to each other prior to the generation and fastening of a curved distance unit.

12. The method for generating a bipolar plate and electrode assembly (7) according to claim 10 or claim 11 , characterised in that the controlled generators (15) are arranged along one or more straight axes and are each movable along said axes and that at least one of the generators are moved along the axis prior to generating and fastening of a curved distance unit to a bipolar plate (1) or an electrode (2; 26; 27).

13. The method for generating a bipolar plate and electrode assembly (7) according to any one of claims 9 - 12, characterised in that, in a plastic deformation process or in an abrasive process the electrode-end further protrusion (9) of the distance unit (3) is flattened in a direction parallel to the electrode (2; 26; 27), and that optionally abrasiveness of the surface parts of the electrode-end further protrusion (9) which are adapted to face the electrode (2; 26; 27) is provided.

14. The method for generating a bipolar plate and electrode assembly (7) according to any one of claims 9 - 13, characterised in that, in a plastic deformation process or in an abrasive process the bipolar plate-end welding foot like protrusion (6) or the electrode end further protrusion is flattened or made pointy.

15. The method for generating a bipolar plate and electrode assembly according to any one of claims 9 - 14, characterised in that, the electrode-end further protrusion(9) of at least some of distance units (3) mounted on a first or second side of a bipolar plate (1) are welded to an electrode (2; 26; 27) by laser welding optionally by feeding the laser radiation through a holding plate (33), such as a plate with through- holes at welding sites, alternatively a transparent plate, preferably with high transparency at a welding laser radiation frequency, whereby the holding plate (33) is adapted to add a predefined compression force to a surface of the electrode during the welding process.

16. The method for generating a bipolar plate and electrode assembly according to any one of claims 9 - 14, [alternative to claim 15] characterised in that the electrodeend further protrusions (9) of some or all distance units (3) mounted on a chosen side of a bipolar plate (1) are welded to an electrode (2;26;27) by chemical reaction and / or combustion welding in a simultaneous welding action.

17. The method for generating a bipolar plate and electrode assembly according to any one of claims 9 - 14, [alternative to claim 16] characterised in that, the bipolar plate end welding foot like protrusion (6) of some or all distance units (3) mounted onto an electrode are welded to the bipolar plate (1) by chemical reaction and / or combustion welding in a simultaneous welding action.

18. The method for generating a bipolar plate and electrode assembly as claimed in any of claims 13 - 16, characterised in that, prior to any welding process between the electrode-end further protrusion (9) and an electrode (2;26;27), the electrode (2;26;27) is simultaneously pressed towards the electrode-end further protrusions (9) and vibrated with respect to the electrode-end further protrusions, such as by vibrating the electrode (2;26;27).

19. An electrolyser unit adapted for electrolysing water into hydrogen and oxygen, and comprising a cell stack having alternatingly a diaphragm and a bipolar plate and electrode assembly whereby the assembly is comprised of a number of singular distance units interposed between and interconnecting bipolar plate and respective cathode and anode electrode, which distance units are adapted to be generated by way of one or more distance unit controlled generators during an assembly and fusion process.

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