Planar parallel convergent gas flow electrolytic device, cell and uses thereof

Abstract

An electrolysis apparatus for producing hydrogen from water includes electrodes and a non-conductive separator layer extending in a substantially vertical plane, including macroscopic through-holes, wherein the electrodes themselves include an anode and a cathode, characterized in that each electrode is mounted on an opposite surface of the separator, and each electrode includes a plurality of fins and wherein each of the plurality of fins protrudes outward from the layer for restricting the upward movement of bubbles generated by the electrodes to a bubble flow substantially parallel to the vertical plane.

Description

[0001] The present invention relates to an electrolysis apparatus for producing hydrogen from water, comprising electrodes and a non-conductive separator layer extending in a substantially vertical plane, wherein the electrodes themselves comprise an anode and a cathode.

[0002] Renewable energy sources such as solar and wind power are becoming increasingly important in the energy mix. A significant issue associated with renewable energy is that these energy sources are often idle (in remote areas) and unschedulable (availability is out of sync with demand). The timeframe for scheduling mismatch ranges from minutes to hours in the case of solar energy due to the diurnal cycle, and from months due to seasonal variations in production and consumption.

[0003] The solution is to convert the collected energy into chemical energy for transport and storage. Both photovoltaic and wind turbines can generate electricity. Through electrolysis, this electricity can be used to separate water into hydrogen and oxygen. The hydrogen can be transported and stored via pipeline for later use, or it can be converted into other substances (such as ammonia) for transport and storage.

[0004] The high cost of electrolysis equipment, currently around €1,000 per kW of installed capacity, is a major obstacle to its widespread adoption. Significant drivers of this high cost are the use of (semi-)precious metals as catalysts and the need to separate the product gases after they have been deposited on the electrodes of the electrolysis unit.

[0005] For gas separation, three methods are described in the literature:

[0006] 1. Use of semi-permeable membranes

[0007] In this method, a membrane of a suitable material (such as Nafion®) is placed between electrodes to maintain the separation of bubbles deposited on the electrodes. The disadvantages of this method are high cost and limited membrane lifespan. It also increases the complexity of the cell structure.

[0008] 2. Force the electrolyte through the porous electrode

[0009] In this method, a pumping system is used to force the electrolyte through electrodes that have been made porous. The flow carries bubbles through the electrodes on which they precipitate and away from the opposite electrode. The disadvantages of this method are increased cost and complexity of the pumping system and increased energy required to maintain sufficient flow.

[0010] 3. Application of hydrodynamics

[0011] In this method, bubbles are kept separate by confining them to the region near the electrode on which they deposit. A drawback of this method is the need to maintain a sufficient electrolyte flow rate, which increases the cost and complexity of the system. It also requires a minimum spacing between electrodes, which reduces the efficiency of the unit.

[0012] At current cost levels, adding electrolysis to renewable energy systems to make the collected energy transportable and storable would at least double the cost of the entire system. More economical methods for electrolysis would allow renewable energy to cover a larger portion of the energy mix.

[0013] Roy E. McAlister's patent No. US 2010213052 A1 (hereinafter US'052) specifically teaches an alternative in which the electrolysis device utilizes buoyancy to separate the generated gases. In US'052, buoyancy is used to guide the flow of bubbles to the "far end" of the opposing electrode. However, it is worth noting that paragraph

[0056] of US'052 gives several reasons to believe that such a solution would require the separation element to be constructed from many parts, which seems challenging in a cost-effective manner.

[0014] US'052 in its Figure 4 Another problem with the implementation described is the mixing of the product gases, where some bubbles formed near the inner edge of the electrode component will rise through the central opening and may coalesce, causing flow disturbances.

[0015] Therefore, the object of the present invention is to provide a cost-effective alternative electrolysis device for replacing semipermeable membranes, porous electrodes and bubble confinement, while maintaining sufficient electrolyte flow.

[0016] Therefore, the present invention is characterized in that each electrode is disposed on the opposite surface of a separator layer, such as a plate, and each electrode includes a plurality of fins, wherein each of the plurality of fins protrudes outward from the separator layer to restrict the upward movement of bubbles generated by the electrodes to a bubble flow substantially parallel to a vertical plane. More preferably, the present invention relates to an electrolysis apparatus in which no space for electrolysis is provided between the electrodes and the separator.

[0017] When viewed in a transverse section, the fins can extend substantially vertically to the main plane of the partition plate. This main plane typically corresponds to the vertical plane used in operation.

[0018] Those skilled in the art will understand that the fins may alternatively project outward in the downward direction, or bend downward along their leading edges, for example, very slightly downward. In either configuration, which is vertical and angled downward relative to the main plane of the separator, the generated bubbles will be restricted in their upward movement and will follow the fins along the vertical plane.

[0019] Electrolysis apparatus can typically be used in units comprising a housing and an aqueous electrolyte solution within the housing, wherein the electrolysis apparatus is arranged within the housing such that the anode and cathode are at least partially immersed in the aqueous solution.

[0020] The simplicity of the unit design provides an opportunity to increase the operating temperature of the electrolysis unit stack while maintaining the stack lifetime. Higher operating temperatures improve catalyst efficiency, making it feasible to replace noble metals with semi-noble metals, while still achieving a limited unit overpotential at reasonable current densities.

[0021] More specifically, the electrode comprises an electrode plate and a plurality of fins protruding therefrom. These electrode plates extend in a plane substantially parallel to the plane of the separator layer. In the case of a parallel-plane electrode as described in this disclosure, this means that the flow direction is parallel to the plane of the electrode. In this disclosure, unlike US'052, the electrolyte body in contact with the opposing electrode is advantageously separated by an impermeable boundary having macroscopic vias, for example macroscopic vias with a width of 1 mm to 200 mm, and optionally forming slits the length of the proximal fins. The macroscopic vias themselves may comprise a permeable membrane, optionally made of the same material as the separator layer but porous. In such a case, the permeable membrane may be integral with the layer. Alternatively, the vias may be provided with a membrane material different from that of the separator layer. In either case, the remainder of the separator layer is designed to be impermeable to the electrolyte. The length of the via along the slit may be discontinuous or continuous. The size of the vias may be separate from any other feature in this section of the specification and may be combined with all embodiments of the invention. Advantageously, due to the design according to the invention, buoyancy is used to guide the bubble flow along a path parallel to the electrode plane, which carries the bubbles around these openings as they rise. The method of this disclosure allows for more compact and easier-to-manufacture unit designs.

[0022] In the arrangement according to the invention, the anode and cathode electrodes are placed back-to-back with an electrical insulator between them to some extent. Here, the separator layer is a plate providing such an insulator. In one example, the ions used (i.e., the electrolyte) can travel between the electrodes through holes distributed on the electrode plates. To prevent bubbles from traveling through these through-holes and mixing, a barrier can be placed directly below each opening to deflect rising bubbles around the opening. Fins can be arranged to form said barrier. Thus, more generally, the separator plate can have through-holes between a plurality of vertically spaced fins, wherein the fins are configured as barriers to prevent rising gas from exchanging through the separator plate.

[0023] To reduce stagnant bubbles (which would otherwise form at the electrodes) and thus improve the contact between the electrodes and water, the plurality of fins on each electrode can be arranged in pairs of upward-converging fins. These fins converge without meeting, thereby merging and releasing the bubble flow from the fins into a single upward flow during operation. "During operation," also separated from this option, refers to a state in which the electrolysis unit is supplied with current while at least partially immersed in water for the active separation of water into hydrogen (H2) and oxygen (O2). By providing a converging flow path for the bubbles, the gas displacement of the water is kept very close to the separator. The buoyancy effect of the rising bubbles draws preferential flow along the fins through the separator, while keeping gas exchange from one side of the separator to the other low. This allows for rapid electrolyte regeneration, which in turn improves the efficiency of the electrolysis unit.

[0024] In one example, the through-holes are macroscopic, meaning they range in width from 1 mm to 200 mm, and are optionally designed as slits with a substantially equal upward angle compared to the converging fins. This arrangement increases the cell's resistance, but with these suitable dimensions, this additional resistance is less than the typical resistance of a semipermeable membrane, and the efficiency loss is considered comparable to the loss from pumping the electrolyte solution. In some embodiments, the electrode portions are integrated into the separator. In other examples, the electrodes are fixed to the outer surface of the separator.

[0025] Optionally, the electrode comprises a metal plate, with fins disposed on such a plate and projecting outward from the partition plate by projecting outward from the metal plate. The barrier (which may be a fin) should be positioned in such a way that, in use, it deflects the bubble flow to a region or channel where the bubbles can subsequently rise unimpeded to the top of the electrode plate. This arrangement reduces the local density of the bubbles along the fins, where density should not be confused with mass density, but is simply given to indicate the local volume ratio of gas to liquid. Furthermore, turbulence is reduced near the opening at the top of the electrode plate. This reduces the mixing of product gases due to the crossing of bubbles between the back-to-back electrodes.

[0026] In one example, the surfaces of electrodes, such as fins, directly below the opening or facing the opposite electrode are covered with a suitable material to prevent air bubbles from forming in these areas. As an example, polytetrafluoroethylene (PTFE) can be used to cover these areas due to its properties as an electrical insulator and its corrosion resistance. However, those skilled in the art will understand that other materials can also be used.

[0027] Improved production performance can be found in the unit design of the electrolysis apparatus mentioned above, where plates separate the internal volumes between the anode and cathode, and the inner wall of the housing of each partition of the unit contains electrically conductive conductors, optionally covered with catalyst, which are electrically connected to the anode and cathode respectively, to improve the efficiency of the unit. More generally, the upper surfaces of the plurality of fins of each electrode can be electrically insulated, for example, by means of a non-conductive coating.

[0028] In one implementation, adjacent pairs of fins are integrally formed into V-shaped ridges. This prevents bubbles from coalescing to form individual rising bubble diffusion columns that could disturb the larger fluid flow in the unit.

[0029] In yet another embodiment, multiple pairs of fins are vertically spaced apart from each other, such that, in use, the upward bubble flow of one pair is added to the upward bubble flow of another pair, and the space between the paired fins defines a vertical bubble path parallel to the vertical plane. This further improves efficiency.

[0030] In one implementation, an alternative V-shaped ridge is proposed, wherein the fins of each electrode are at least substantially angled upwards to allow the bubble flows from the fins to merge and release into a single upward flow during use. When the cell scale increases and multiple openings in the cell, such as more than five overlapping, the V-shaped ridge can negatively impact gas separation. Gas separation is typically a critical aspect of hydrogen electrolysis, as the mixing of hydrogen and oxygen can lead to significant reactions, often in the form of explosions, negatively affecting cell performance and even causing cell failure—which is certainly undesirable.

[0031] To further prevent explosion hazards and facilitate unit expansion, particularly in the vertical direction, fins can be made to protrude slightly relative to their complementary through-holes, for example, by using protruding ends. In this context, a fin protruding end refers to the portion of the fin that extends beyond the main structure. Or, in other words, the portion of the fin that extends beyond the through-hole. By guiding fluid flow around the fins, the fin protruding ends offer advantages in controlling bubbles, thereby reducing eddies. Eddy formation adversely affects efficiency and safety by causing turbulent mixing of hydrogen and oxygen gases, leading to a potential explosion hazard. Furthermore, eddies hinder the release of bubbles from the electrode surface, thereby reducing the effective reaction area and resulting in uneven current distribution.

[0032] For the purpose of illustrating the invention, the accompanying drawings show embodiments of the disclosed subject matter. However, it should be understood that this application is not limited to the precise arrangements and means shown in the schematic diagrams:

[0033] Figure 1 A cross-section of an example arrangement of back-to-back anodes and cathodes with openings and barriers is shown.

[0034] Figure 2 An example arrangement of openings, barriers, and channels for collecting bubbles is shown, as well as the direction of bubble flow resulting from this arrangement.

[0035] Figure 3 An example arrangement of the entire collector plate, including barriers that conduct product gases to opposite sides of the electrolysis unit stack, is shown.

[0036] Figure 4 An example arrangement of a portion of a stack of collector plates, including a gas separation barrier, is shown.

[0037] Figure 5 A cross-section of an electrolysis unit with example dimensions is shown.

[0038] Figure 6 An example arrangement of openings, barriers, and channels for collecting bubbles is shown, along with the direction of bubble flow generated by the arrangement, wherein the arrangement shows fins angled upwards.

[0039] exist Figure 1 In the diagram, an electrolysis device 100 is shown in cross-section. This electrolysis device is used to produce hydrogen from water and includes electrodes and a non-conductive partition plate 3 extending in a substantially vertical plane, including macroscopic through-holes 7. In this example, the width of these through-holes is 2 mm, but these dimensions are not fixed and those skilled in the art will know that these dimensions can be varied depending on the dimensions of the unit intended for assembly. The electrodes themselves include an anode 1 and a cathode 2, characterized in that electrodes 1 and 2 are each mounted on opposite sides of the partition plate 3. Electrodes 1 and 2 each have a plurality of fins 4 and 5, and each of the plurality of fins protrudes outward from the plate 3 to restrict the upward movement of bubbles generated by the electrodes to a bubble flow substantially parallel to the vertical plane. The electrolysis device is also shown as being applied to an electrolysis device unit 1000. Furthermore, separate from this example, the plurality of fins are designed to extend to the inner wall of the unit's housing. The fins thus form a barrier by protruding from the plate of the electrodes themselves. Electrodes 1 and 2 may be formed from punched metal sheets. The through-hole 7 is shown as being disposed on the partition plate 3 between the vertically spaced fins 4 and 5. At least in this example, the upper surface of each fin is covered with an electrically insulating coating to prevent bubble formation. Suitable materials for this coating are polytetrafluoroethylene (PTFE) or perfluoroalkoxyalkane (PFA) because these materials combine excellent corrosion resistance with good electrical insulation. The coating can be applied using a powder coating technique that covers a portion of the electrode while applying the powder. This arrangement deflects the bubble flow away from the opening and towards the top of the electrode plate. This reduces the amount of bubbles that cross to the other side of the anode-cathode assembly and thus improves the separation of the product gases.

[0040] The space between the electrode plates is occupied by a partition plate 3, which serves as an electrical insulator completely covering the area of ​​the plates facing each other. The electrode plates themselves are interrupted where the through-holes extend between the partition plates 3. The exposed portions of the partition plates 3 are covered with a coating to protect them from corrosion. If PTFE or PFA is used to insulate the ridges x1, enamel is a suitable material for insulating the partition plates 3 because it can withstand the temperatures required to bake the PTFE / PFA coating and can be easily applied to metal. Furthermore, separate from the above and compatible with all embodiments, each electrode plate includes a ridge x1 projecting outward from the plate for guiding rising bubbles from the plurality of fins 4, 5 of the electrode to an outlet during use. This ridge may also be at least partially curved along the plane of the electrode.

[0041] Figure 2 One side of one of the electrodes 1 and 2 of the electrolysis apparatus 100 is shown. Here, it is shown that "the electrode includes a plate that also includes a through-hole 7.1 corresponding to the through-hole 7 of the partition plate." Note that the referenced portion can be introduced separately as a feature in the claims because it is compatible with all embodiments of the invention. In a more detailed example, fins 4 and 5 are punched from the electrode plate. Each fin is integral with the adjacent fin, forming a shallow V-shape with rounded corners. The upward angle of the two fins 4 and 5 deflects the flow of bubbles to the side and around the openings between other fins that also form a V-shape facing the top of the plate. The rounded corners are intended to limit the stretching of the material when punching the barrier. Here, "shallow" means that the angle between the overall fins is 100 to 170 degrees.

[0042] Reference Figure 3 In some implementations, a plurality of fins 4 and 5 form pairs of 45 and V-shaped fins, such as Figure 2 As described in detail, the space between the V-shaped fins defines a channel for the upward movement of the generated bubbles. Ridges x1, formed by bending a portion of the electrode plate, laterally deflect the rising bubble flow x2, thus all gas precipitated on the electrode plate exits to one side of the plate. In the assembled stack, these ridges press against the plates that separate the units. The opposing electrodes have similar ridges that deflect the bubble flow to the opposite sides of the electrode plates. This arrangement allows for the collection of product gases on opposite sides of the unit stack. The product gases can be further separated by a barrier x3 between the top of the unit stack and the containment container. A support x7 keeps the unit stack isolated from the containment container.

[0043] Each separator plate makes electrical contact with the adjacent anode and cathode via punched protrusions (also referred to as the aforementioned fins 4, 5, and ridge x1). An electrical insulator between the anode and cathode provides electrical insulation between consecutive units, eliminating the need for individual washers and further simplifying the manufacture of the stack. The unit stack can be manufactured by alternately stacking combined anode / cathode plates and separator plates between two end plates connected by a tension bar or spring.

[0044] Reference Figure 4 In the cross-section, a transverse stack of collectors and separators, y1, is visible. A gas separation barrier, y2, is placed on top of the stack. The barrier is formed of a single sheet material with sufficient elasticity to ensure an airtight fit with the top of the stack. The barrier's protrusion, y3, is fitted onto ridges that laterally deflect the bubbles (such as...). Figure 3 In the gap formed by the mark x1 in the middle.

[0045] Reference Figure 5 At the dimensions shown, the resistivity of the electrolyte (35 wt% KOH, at 50 °C and a current density of 0.5 A / cm²) contributes approximately 0.6 V to the cell overpotential, which is the same as that of a standard cell with a 4 mm gap between the electrode and the semipermeable membrane. For a forced electrolyte flow-based method, the overpotential of a standard cell with a 4 mm gap is approximately 0.4 V. When the operating temperature is increased to 150 °C (which would be impractical when using a membrane), the contribution of the electrolyte resistivity decreases to 0.3 V. Therefore, the overpotential loss of the currently disclosed arrangement is the most limited and can be completely avoided by selecting a higher operating temperature.

[0046] Reference Figure 6 The diagram shows a plurality of fins 4, 5 for each electrode, which are at least substantially angled upwards for merging and releasing the bubble flows from the fins into a single upward flow during use. This is advantageous because it promotes gas separation, and larger cells can be constructed with more significant overlap of the through-holes 7. Each fin preferably includes a protruding end 5.1 that at least partially protrudes beyond the through-hole 7, for example, at least 1 mm, to advantageously prevent one or more eddies in the upward bubble flow, ultimately preventing gas mixing.

[0047] Figure 6The following features, distinct from this particular example, are specifically illustrated and can be applied to the invention. The plurality of fins 4, 5 of each electrode can be angled upwards at least substantially relative to the horizontal plane “HZ”. In this particular example, it has been found that 25 to 45 degrees promotes stable bubble flow during use. Furthermore, guide fins x1.1 can be provided to guide and merge the bubble flow of the fins into an upward flow during use. This upward-moving bubble flow is preferably guided at an angle relative to the vertical plane to prevent eddy disturbances to the stable fluid flow along the electrode. For this purpose, guide fins x1.1, particularly their guide surfaces, can be designed to be substantially vertical to the direction in which the fins extend along the partition plate 3, at an angle of 80 to 100 degrees relative to that direction. Preferably, the distance between the ends of the successive fins of the plurality of fins 4, 5 and the guide fins x1.1 increases or remains constant in the upward direction. This advantageously accommodates increasingly larger gas flows as the flow merges. For this purpose, fins x1.1 are preferably angled at 90 to 95 degrees relative to the direction in which the fins extend along the partition plate.

[0048] The design of through-hole 7 is completely different from that of this particular illustrated example, but... Figure 6 As shown in the diagram, from a view facing the partition plate 3, each through-hole 7 is designed to extend along one of the plurality of fins 4, 5 through a slit in the partition plate 3, and the slit narrows in the direction of fin as the fins rise. Advantageously, this allows the bubble flow to become larger as the fins rise, without allowing bubbles to cross over, while also allowing efficient exchange between components dissolved in the liquid.

[0049] A particular design was found to be most favorable for the linear cumulative increase in bubble flow size. For this purpose, the slit can be designed as an irregular quadrilateral in which the angles of the quadrilaterals are not equal to each other and the height of the quadrilaterals narrows in the direction of fin rise. Figure 6 An exaggerated view of the quadrilateral is shown on the right-hand side.

[0050] Figure 7 The guide fins also allow for a tighter horizontal spacing between the fins and openings in the vertical array, resulting in more efficient utilization of the available surface area within the cell. Here, the term "array" refers to an inclined columnar structure, such as that formed by the fins. The inclined columnar structure in... Figure 6 This can also be seen in the text.

[0051] Figure 7 The diagram shows that each electrode may include additional fins 4', 5', also forming an array, such as an inclined columnar structure. This arrangement is advantageous for gas generation. However, this configuration requires a fairly large array spacing. In this particular embodiment, however, a portion of one array of fins extends vertically above the array. This is typically not the case because in other cases, bubbles would cross between the arrays. This would hinder production and disrupt fluid flow. However, in... Figure 7In this configuration, guide fins x1.1 extend between these arrays to prevent bubbles from crossing between structures. For this purpose, the length of the guide fins is preferably 80% to 120% of the length of the array (measured as the distance between the lower and upper fins in the same array). It is reasonable to assume that additional plurality of fins 4', 5' could be provided with their own guide fins x1.1' for repeatability. Figure 6 The design.

Claims

1. An electrolysis device (100) for producing hydrogen from water, comprising electrodes (1, 2) and a non-conductive separator layer (3), such as a plate, extending in a substantially vertical plane, including macroscopic through-holes (7), for example macroscopic through-holes (7) with a width of 1 mm to 200 mm, wherein the electrodes themselves comprise an anode (1) and a cathode (2). Its features The electrodes (1, 2) are each mounted on the opposite side of the separator (3), and each electrode (1, 2) includes a plurality of fins (4, 5) and each of the plurality of fins protrudes outward from the separator layer (3) so as to restrict the upward movement of the bubbles generated by the electrodes to a bubble flow substantially parallel to the vertical plane during use.

2. The electrolysis apparatus according to claim 1, wherein each electrode comprises a single plate extending in a plane parallel to the plane of the vertical plane of the separator layer (3), for example, a single plate integral with the plurality of fins of the electrode.

3. The electrolysis apparatus according to claim 2, wherein the plate of each electrode includes an outwardly projecting ridge (x1) for guiding rising bubbles from the plurality of fins (4, 5) of the electrode to an outlet during use.

4. The electrolysis apparatus according to claim 1, 2 or 3, wherein the plurality of fins (4, 5) of each electrode are at least substantially angled upward, for example, 10 to 45 degrees with respect to the horizontal plane, preferably 25 to 45 degrees, and wherein guide fins (x1.1) are provided for guiding and merging the bubble flow of the fins into an upward flow during use, wherein the guide fins are preferably angled at 80 to 100 degrees with respect to the direction in which the plurality of fins extend, more preferably 90 to 95 degrees.

5. The electrolysis apparatus according to claim 4, wherein the plurality of fins form an inclined columnar structure.

6. The electrolysis apparatus of claim 5, wherein each electrode includes a plurality of additional fins (4', 5') that also form inclined columnar structures, and wherein a portion of one of the inclined columnar structures extends vertically above the other columnar structure, and wherein the guide fins (x1.1) extend between these structures to prevent air bubbles from passing between the structures during use.

7. The electrolysis apparatus according to any one of claims 1 to 6, wherein each of the macroscopic through holes (7) is designed to extend through a slit of the partition plate (3) along one of the plurality of fins (4, 5) and the slit narrows in the direction of the rising of the fin, and wherein the through hole is preferably designed as an irregular quadrilateral with unequal angles.

8. The electrolysis apparatus according to claim 1, 2, 3 or 4, wherein the plurality of fins (4, 5) of each electrode form pairs of upward converging fins (45), and wherein the fins of each pair of fins converge without meeting, so that the bubble flow of the fins merges and releases into an upward flow in use.

9. The electrolysis apparatus according to claim 8, wherein the adjacent pairs of fins (45) are integrally formed as a V-shaped ridge (V) with a shallow angle of 100 to 170 degrees, preferably 120 to 150 degrees, between the pairs.

10. The electrolysis apparatus according to any one of claims 8 or 9, wherein the plurality of pairs of fins are vertically spaced apart from each other such that, in use, an upward bubble flow from one pair of the plurality of pairs of fins is added to an upward bubble flow from another pair, and wherein the space between the pairs of fins defines a vertical bubble path parallel to the vertical plane.

11. The electrolysis apparatus according to any one of claims 1 to 9, wherein the upper surface of the plurality of fins of each electrode is electrically insulated, for example by a non-conductive coating.

12. The electrolysis apparatus according to claim 11, wherein the through hole (7) is disposed between the vertically spaced fins of the plurality of fins, and is located vertically above each fin along the plurality of fins, wherein the fins are configured as barriers to prevent rising gas from being exchanged through the separator layer (3).

13. The electrolysis apparatus according to any one of claims 1 to 12, wherein each of the fins includes a protruding end (5.1) that protrudes at least partially beyond the through hole (7), for example, protruding beyond the through hole (7) by at least 1 mm.

14. An electrolysis apparatus unit, comprising: - A shell that defines the internal volume; - The electrolyte aqueous solution inside the shell; and - An electrolysis device (100) arranged within the housing according to any one of claims 1 to 13.

15. The unit of claim 14, wherein the sides of the housing are fluid impermeable, and wherein the side walls facing the internal volume are provided with electrical conductors associated with the electrodes to increase the total effective surface area of ​​the electrodes of the electrolysis device.

16. A stacked arrangement of electrolysis apparatus units, comprising laterally and vertically adjacent units, wherein the units are those according to claim 14 or 15.

17. Use of the electrolysis unit according to claim 14 or 15.

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