ELECTROLYSIS DEVICE

Description

[0001] The invention relates to an electrolysis device with a plurality of electrolysis cells which are electrically connected in series and which are at least partially arranged successively in a stacking direction in a cell stack, wherein the series connection can be electrically coupled to an electrical energy source, with a cell supply unit for supplying the electrolysis cells in intended operation with at least one operating substance, and with supply lines connected to the cell supply unit and to the cell stack, wherein one material of the supply lines is metal.

[0002] Electrolysis cells, which serve to convert chemical substances into other chemical substances under the influence of electricity, are well known in the art. Generally, a chemical reaction, i.e., a transformation of substances, is brought about by means of an electric current. This is called electrolysis. A well-known and widely used form of electrolysis is water electrolysis. In water electrolysis, water is broken down into its components, namely hydrogen and oxygen, using an electric current. In principle, however, other substances can also be subjected to electrolysis, for example, carbon dioxide or the like.

[0003] These are typically fluid substances that can be supplied to the electrolysis cells via appropriate supply lines, where the actual electrolysis takes place. The electrolysis products are often also in fluid form and are discharged from the electrolysis cells via further supply lines. These supply lines are generally connected to a cell supply unit, which serves to supply the electrolysis cells with the respective substances, or at least one operating substance, for their intended operation. "Supply" here therefore means not only the introduction of the operating substance or the substance to be electrolyzed, but also the removal of the respective electrolysis product.

[0004] The provision of hydrogen is proving particularly interesting from an industrial perspective, especially since hydrogen can be a versatile energy carrier. Hydrogen can be produced using an electrolysis unit, also called an electrolyzer, utilizing regeneratively generated electrical energy. One method of hydrogen production involves using an electrolysis unit whose electrolysis cells are based on proton exchange membranes (PEMs). The principle of a PEM-based electrolysis unit or PEM-based electrolysis cell is known in the prior art, so further explanation is omitted. For example, an electrolysis cell for producing hydrogen and oxygen from water is disclosed in DE 10 2011 007 759 A1. DE 10 2019 205 316 A1 also discloses a corresponding electrolysis cell for energy-efficient hydrogen production.Furthermore, DE 21 2018 000 414 U1 discloses a hydrogen production system.

[0005] Electrolysis systems of this type typically consist of multiple electrolysis cells, which are usually connected in series. This series connection is electrically coupled to an electrical power source that provides a suitable voltage, enabling the electrolysis cells to carry out the intended electrochemical conversion process.

[0006] Furthermore, the electrolysis cells are arranged consecutively in a stacking direction, forming a cell stack. This stacked arrangement allows the consecutive electrolysis cells to be electrically connected directly, thus largely eliminating the need for separate electrical connections.

[0007] Within the cell stack, a supply line system with cell connection lines (manifold) or a supply structure is provided, which serves, among other things, to supply and remove at least one operating fluid to the electrolysis cells. The operating fluid can include, for example, the supplied fluid, such as water, and / or the reaction product, such as hydrogen and oxygen. The cell stack is generally operated at a specific electrolysis power such that the electric current is as low as possible, but the electric voltage is as high as possible. This is achieved by appropriately stacking the electrolysis cells within the cell stack.This allows electrical voltages at the respective electrolysis cells in the cell stack to add up to the cell stack voltage, while the electrolysis cells connected in series in this way can be operated with essentially the same current.

[0008] The electrolysis power is provided by the energy source, which can be connected to opposite ends of the cell stack for this purpose. A cell stack can contain a large number of electrolysis cells, for example, more than 100 electrolysis cells, in particular several hundred electrolysis cells, but preferably not more than about 400 electrolysis cells. During the electrolysis of water to hydrogen and oxygen, the electrical voltage across each electrolysis cell is approximately 1.5 V to 2.5 V. The resulting electrical voltage across the cell stack is correspondingly high, often exceeding 100 V and potentially reaching several hundred volts.

[0009] The electrolysis unit comprises, in addition to the cell stack, other components such as pumps, heat exchangers, and separators, which are necessary for the intended operation of the electrolysis unit and / or the electrolysis cells. These components are combined here by the cell supply unit, which provides the electrolysis cells with at least one operating fluid for their intended operation.

[0010] The cell supply unit is connected to the electrolysis cells, which are arranged sequentially in a stacking direction, via supply lines that are connected to the opposite ends of the successive electrolysis cells. The supply lines are generally made of a material such as metal or the like.

[0011] A correspondingly high electrical voltage arises between the ends of the cell stack or the successively arranged electrolysis cells. Therefore, the supply lines, which are usually made of metal, must have electrically insulating sections to prevent a highly conductive connection between the ends of the successively arranged electrolysis cells and thus between the electrical connections of the power source.

[0012] While the application has proven effective according to the state of the art, it has been found that corrosion can occur, particularly in the section of the supply line adjacent to the electrical insulation, which is exposed to a positive electrical potential from the power source during normal operation. This is not only detrimental to the electrolysis unit itself, but can also lead to contamination of at least one operating fluid and thus to malfunctions in the intended operation of the electrolysis cells.

[0013] To mitigate this problem, it is known in the prior art to keep the specific electrical conductivity of water as low as possible and to kinetically inhibit corrosion by using the longest possible insulation distance or by reducing the cross-section in the area of ​​the respective insulating section, thus extending the effect over time. However, this does not fundamentally prevent corrosion. In particular, the always present, albeit slight, electrical conductivity of water, especially within the insulating distance formed by the insulating section, leads to stray currents in the water, particularly within the insulating distance. Therefore, the problem of corrosion persists.

[0014] The invention is based on the objective of reducing the aforementioned corrosion problem.

[0015] The invention proposes a solution in the form of an electrolysis device according to independent claim 1.

[0016] Advantageous further training opportunities arise from the characteristics of the dependent requirements.

[0017] With regard to a generic electrolysis device, the invention particularly proposes that the supply lines are connected exclusively to a first end of the cell stack, so that the first end of the cell stack is electrically coupled to the cell supply unit, wherein the first end of the cell stack can be coupled to a negative electrical potential of the electrical energy source.

[0018] The invention is based, among other things, on the idea that the inventive design of the electrolysis device allows the supply lines to be arranged or connected only at the first end of the cell stack. This enables the supply lines to be kept at essentially the same electrical potential, which preferably corresponds to an electrical reference potential of the cell supply unit, thus largely eliminating the need for insulating sections in the supply lines. The supply lines can therefore provide electrical coupling or an electrical connection between the first end of the cell stack and the cell supply unit. Preferably, one of the two electrical potentials of the electrical power source can also be connected at the first end of the cell stack.The electrical reference potential of the cell supply unit can, for example, be an electrical ground of the cell supply unit or the like. This largely avoids, if not completely prevents, the corrosion described above. Preferably, the second end of the cell stack is designed without supply lines. Only the other electrical potential of the electrical power source needs to be connected at the second end of the cell stack. Harmful, corrosion-promoting electrical potential differences in the area of ​​the supply lines can thus be largely avoided, especially since the supply lines themselves are electrically conductive.

[0019] Preferably, the negative electrical potential of the electrical power source is connected to the first end of the cell stack, and the positive electrical potential of the electrical power source is connected to the second end of the cell stack. The potential difference between the first and second electrical potentials of the electrical power source determines an electrical voltage applied to the cell stack. Due to the series connection of the electrolysis cells, a partial electrical voltage is applied to each electrolysis cell.

[0020] The design according to the invention makes it possible, among other things, to reduce the corrosive effect because the conditions detrimental to corrosion can be reduced. Due to the electrical potential difference at the insulating sections of the supply lines, an electric current can occur in the fluid flowing through the respective supply line, particularly if it is water, in the prior art. As a result, hydrogen and hydroxide ions can be released. The invention reduces or even completely eliminates the conditions relevant to the corrosive effect, namely, in particular, the presence of hydroxide ions. They are therefore no longer available for the undesirable corrosive effect. Overall, the invention thus makes it possible to reduce or even completely avoid the undesirable corrosion effect.

[0021] The electrolysis cells can, for example, be arranged sequentially in a single cell stack. Preferably, the electrolysis cells within the cell stack are electrically connected in series. The opposite ends of the cell stack, namely the first and the second end, can be connected to the respective electrical potentials of the electrical power source. They can, for example, be connected directly to the electrical power source. Preferably, however, they are connected to the electrical power source via a control unit, so that the function of the electrolysis cells can be adjusted as needed.

[0022] The electrical energy source can be, for example, any voltage or current source capable of providing sufficient power for the electrolysis process to be carried out by the electrolysis cells. The electrolysis power can be determined at a specific surface current density depending on the dimensions of the respective electrolysis cell, particularly its electrolytically effective areas.

[0023] The supply lines have a through-opening with a suitable inner diameter or cross-section in order to be able to convey the respective operating material to the electrolysis cells with as little loss as possible and / or to be able to convey it away from the respective electrolysis cells with as little loss as possible.

[0024] In principle, it is sufficient if only one of the supply lines is fully electrically conductive. Some or all of the other supply lines then do not need to provide electrical conductivity between their respective ends. These supply lines can have electrical insulating sections, so that their opposite ends are electrically isolated from each other. The electrical insulating sections of these supply lines can, for example, be made of a suitable material that can be mechanically bonded to the respective supply line. For example, it could be a ring-shaped section located at each end of a supply line.Furthermore, the insulating section can of course also be integrated into the supply line, so that the supply line has two electrically isolated supply line sections separated from each other by the insulating section. These units formed in this way are preferably fluid-tight, with a substantially constant internal cross-section preferably being provided for the respective operating fluid.

[0025] The material for the electrical insulating section can be, for example, a plastic, a ceramic, or a metal oxide such as titanium dioxide, aluminum oxide, and / or the like. Furthermore, a composite material can also be used, which, for example, could be made of a plastic that is fiber-reinforced. Of course, virtually any combination of these materials is possible, preferably selected in such a way that a chemical reaction with the operating fluid is essentially avoided.

[0026] The material of the supply line contains at least some metal. This metal could be, for example, steel, particularly stainless steel. Of course, other metals, such as titanium or similar materials, could also be used. Naturally, appropriate metal alloys could also be used.

[0027] According to a further development proposal, the cell stack is designed to include cell connection lines, also called manifolds, for fluid coupling of the electrolysis cells to the supply lines connected at the first end. This allows the supply lines to be fluidly coupled to the electrolysis cells. The cell connection lines can be provided by the cell stack itself, similar to a cell stack supply structure. Therefore, no separate supply structure needs to be provided within the cell stack to connect the electrolysis cells to the supply lines. This also simplifies the connection of the supply lines to the cell stack. The cell connection lines are preferably integrated into the cell stack. For example, each electrolysis cell could provide a section of its respective cell connection line.By stacking the electrolysis cells, the respective sections can then be fluidically connected and sealed, so that the respective cell connection lines can be formed.

[0028] It is further proposed that each cell connection line has a through-opening designed to minimize pressure drop across the lines, ensuring consistent operation of the electrolysis cells. Preferably, the pressure drop is as small as possible, ideally negligible, during normal operation of the electrolysis system. This allows the electrolysis cells to be subjected to essentially the same stress levels during normal operation, even though they are supplied via lines connected exclusively to the first end of the cell stack. For example, a sufficiently large inner diameter can be used for the cell connection lines, such that the pressure drop across a given length of the respective cell connection lines is small compared to the operating pressure at the electrolysis cells.However, it is also possible that the inner diameter of the cell connection leads depends on the distance of each lead position from the first end of the cell stack. For example, the inner diameter can decrease, at least partially, with increasing distance from the first end of the cell stack.

[0029] To further improve the effectiveness of the invention, it is proposed that the through-hole have an inner surface coated with an anodically stable layer. This anodically stable layer ensures that any hydroxide ions present find essentially no reaction partner, thus further reducing the corrosion effect. The anodically stable layer could, for example, comprise a plastic, a metal oxide such as titanium dioxide, or the like.

[0030] According to further research, it is proposed that the cell connection leads be at least partially non-metallic. For example, the cell connection leads could be made of a plastic, a ceramic material, or similar materials. This would prevent the formation of metal ions, which could lead to undesirable corrosion or the aforementioned impurities.

[0031] Furthermore, it is proposed that the cell connection leads be at least partially electrically insulated. This allows for electrical isolation of the electrolysis cells arranged consecutively or stacked, particularly in cell stack configurations. Therefore, no separate electrical insulation measures are required for supplying power to the electrolysis cells. The cell connection leads can, for example, have a layer of a suitable material on the inside of their through-holes. This layer can consist of a coating of an electrically non-conductive plastic, an electrically non-conductive ceramic material, or the like.

[0032] Furthermore, it is proposed that the supply lines be designed without insulating sections, at least in part. This allows the supply lines to be formed essentially homogeneously from a single material, for example, metal, particularly stainless steel, and enables good electrical coupling between the first end of the cell stack and the cell supply unit. Preferably, the supply lines are essentially identical, at least with respect to the material. They can also have the same internal cross-section.

[0033] It is further proposed that the cell supply unit be at least indirectly electrically grounded. This grounding allows the cell supply unit and its electrically coupled supply lines to be connected to a predetermined reference potential. This also allows the negative potential of the electrical power source, which is electrically coupled to the cell supply unit via the supply lines, to be at least indirectly grounded as well. Unlike in the prior art, the cell stack is thus at a defined electrical potential relative to ground and therefore no longer exhibits a floating potential. This largely eliminates any electrical potential difference or voltage in the vicinity of the supply lines. This further improves the reliability of the invention.

[0034] Furthermore, it is proposed that the grounding system include a sacrificial anode and / or a voltage source by means of which the cell power supply unit can be supplied with an electrical potential negative relative to ground potential. This allows for cathodic corrosion protection. If a voltage source is used, its negative potential can be electrically connected to the cell power supply unit and to the supply lines connected to it. The negative potential of the voltage source is preferably also grounded. For optimal performance of the corrosion protection achieved in this way, the voltage source can provide an electrical voltage in the range of approximately -2 V to approximately zero volts relative to ground potential. It is particularly advantageous if this voltage is selected in the range of approximately -1 V to approximately -0.8 V.By selecting an electrical voltage within this range, corrosion of materials such as stainless steel can be prevented even under marine conditions, particularly in offshore applications. In particular, this can reduce or prevent external corrosion.

[0035] To reduce or prevent internal corrosion, it is preferable to arrange an additional electrode, similar to a counter electrode used for grounding, for cathodic corrosion protection within the cell supply unit. Internal corrosion refers in particular to corrosion effects within the electrolysis unit, especially within the cell supply unit. This electrode, for example, could be a titanium electrode or titanium anode coated with a mixed oxide. Preferably, the anode formed in this way is located in the liquid phase of an oxygen separator within the cell supply unit.

[0036] It is particularly advantageous for the sub-stacks to be connected in parallel to the cell supply unit. This ensures a reliable supply of at least one operating fluid to each sub-stack. The supply can include adding or removing the operating fluid or substances generated during electrolysis.

[0037] Supply structures integrated into the cell stack or electrolysis cells, particularly the cell connection lines, can serve as internal insulation. Materials used to contact the water to be electrolyzed within the cell stack, except in the area of ​​the respective active cell surfaces of the electrolysis cells, must meet at least one of the following three requirements: The materials are non-metallic; electrically potential-stressed metals are coated with an oxidation-stable layer such as titanium dioxide, a polymer, or the like; uncoated metals are not electrically connected, i.e., essentially electrically potential-free, especially floating.

[0038] The invention makes it possible, among other things, to enable the electrodes of the active cell surfaces of the electrolysis cells to act as anodic counter electrodes. This allows, for example, a slightly higher oxygen output at the respective anodes of the electrolysis cells and a slightly lower hydrogen output at the respective cathodes. However, these changes during electrolysis do not significantly affect the efficiency and safety of the electrolysis system. Rather, the advantage of the invention is that no foreign ions can be released from metallic elements due to stray currents.

[0039] The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the figure description and / or shown in the figures alone, can be used not only in the combination specified but also in other combinations without leaving the scope of the invention.

[0040] The embodiments described below are preferred embodiments of the invention. The features and combinations of features specified above in the description, as well as those mentioned in the following description of embodiments and / or shown individually in the figures, are not only usable in the combinations specified, but also in other combinations. Thus, embodiments are also encompassed by the invention or are considered disclosed that are not explicitly shown and explained in the figures, but can be derived and generated from the described embodiments by separate combinations of features.The features, functions, and / or effects illustrated by the exemplary embodiments can each, considered independently, represent individual features, functions, and / or effects of the invention, each of which further develops the invention independently. Therefore, the exemplary embodiments are intended to include combinations other than those described in the embodiments. Furthermore, the described embodiments can also be supplemented by additional features, functions, and / or effects of the invention already described.

[0041] In the figures, the same reference symbols denote the same features or functions.

[0042] They show: FIG 1 A schematic block diagram of an electrolysis device for electrolyzing water; FIG 2 a schematic cross-sectional view of a supply line of the electrolysis plant according to FIG 1 in the area of ​​an insulating section; FIG 3 a schematic block representation such as FIG 1 a further electrolysis device for electrolyzing water, in which supply lines are connected only at a first end of a cell stack according to a first embodiment; and FIG 4 a schematic representation of FIG 3 for a second design of the electrolysis unit.

[0043] FIG 1 Figure 1 shows a schematic block diagram of an electrolysis device 10, which has a cell stack 54 comprising a plurality of electrolysis cells 12 arranged successively in a stacking direction 14. The electrolysis cells 12 serve to decompose water into its components oxygen and hydrogen by electrochemical means. The electrolysis device 10 therefore serves to produce hydrogen and oxygen from water.

[0044] The electrolysis cells 12 are arranged directly adjacent to each other, so that the respective electrodes of the adjacent electrolysis cells 12 can electrically contact each other. It is provided that an anode of the first electrolysis cell 12 electrically contacts a cathode of the immediately adjacent second electrolysis cell 12. This connects the electrolysis cells 12 in series.

[0045] The electrolysis cells 12 are supplied with water for electrolysis via an internal supply structure of the cell stack 54 (not shown in further detail), and connections for the produced substances hydrogen and oxygen are provided on the other hand. This supply is designed to be connectable at opposite ends 20 and 22 of the cell stack 54.

[0046] Furthermore, an electrical energy source 16 is connected to the ends 20, 22 via an electrical line 52, which in this case provides a suitable electrical voltage with a suitable electrical power, so that the electrolysis cells 12 can be adequately supplied with electrical energy for the intended operation.

[0047] The electrolysis unit 10 further comprises a cell supply unit 18, which serves to supply the electrolysis cells 12 or the cell stack 54 with the respective operating fluids, in this case the supply of water and the removal of hydrogen and oxygen. The cell supply unit 18 comprises several components that are necessary for the intended operation of the electrolysis unit 10, such as pumps, heat exchangers, separators, and / or the like, which are not shown in detail here. The cell supply unit 18 is connected to the cell stack 54 via supply lines 24, which are connected to the cell supply unit 18 and the opposite ends 20, 22 of the cell stack 54. The supply lines 24 thus provide the fluid coupling to the supply structure of the cell stack 54.The supply lines 24 are made of a metal such as stainless steel.

[0048] To prevent a short circuit between the ends 20 and 22 of the cell stack 54 via the metal supply lines 24, each supply line 24 has an electrical insulating section 38. This ensures that the ends 20 and 22 are electrically insulated from the cell supply unit 18 and thus also from each other. The supply lines 24 are located outside the cell stack 54.

[0049] The insulating sections 38 are in this case essentially formed from an electrical insulating material, which can be, for example, a suitable ceramic material or a suitable plastic or composite material.

[0050] FIG 2 shows a schematic sectional view of one of the supply lines 24 from FIG 1 in the area of ​​insulation section 38. In FIG 2 The supply line 24 is shown with a first section 58 facing the end 22 of the cell stack 54, whereas an opposing second section 56 faces the cell supply unit 18. The sections 56 and 58 are electrically separated from each other by the insulating section 38. This arrangement is designed to be fluid-tight overall and has a substantially constant inner diameter 62 through which the fluid, in this case water, can flow.

[0051] Due to the electrical voltage applied to the electrical insulating section 38, corrosion occurs in area 64. This can be explained by the fact that, in the area of ​​a transition from area 56 to the electrical insulating section 38, negative hydroxide ions are formed by the uptake of electrons from the metal wall of the supply line 24 into the water flowing in the inner diameter 62. These ions are then carried to area 58 by the electric field and react electrochemically with the metal wall of the supply line 24, as shown in FIG 2 As shown, this causes the wall of supply line 24 to corrode in this area 64. This is undesirable.

[0052] For this type of corrosion, it is important to consider that a DC voltage of several hundred volts can typically be present across the electrical insulating sections 38 during normal operation. This can lead to an excess of electrons in region 56 and an electron deficiency in region 58 of the electrical insulating section 38. Due to the magnitude of the electrical voltage across the electrical insulating section 38, electrode reactions occur from a thermodynamic perspective, as previously explained. While reducing the electrical voltage can extend the duration of the corrosion effect, thus inhibiting it kinetically, it cannot completely prevent it. Similarly, lengthening the insulation distance using the electrical insulating section 38 or reducing its inner diameter 62 can only inhibit the corrosion effect, but not prevent it.

[0053] In area 56, the hydrogen produced can be dissolved in the water or exist in the form of minute bubbles and be carried away with the water. The quantities produced are generally so small that the hydrogen itself has no adverse effects.

[0054] However, this does not apply to the hydroxide ions that are present in dissolved form in the water. Due to their negative charge and the direction of the electric field in the area of ​​the electrical insulating section 38, they tend to migrate from area 56 to area 58. In this area 58, the metallic material of the supply line 24 is then oxidatively decomposed. FIG 2 This degradation is illustrated for the case where the supply line 24 is made of stainless steel. However, this effect is not limited to steel, but can occur with almost any other metallic material.

[0055] Besides the release of iron, other metals that may be present in the steel can also dissolve. This process can form cations. Due to their positive charge, the metal cations tend to migrate in the opposite direction to the hydroxide ions. This can lead to the formation of so-called rouging from the metal cations, especially iron ions, and the hydroxide ions. Rouging refers to very fine iron-containing particles that can be distributed in the supply lines 24 and the components of the electrolysis unit 10. They can be observed particularly in the supply lines 24, which also carry hydrogen. If this rouging reaches the oxygen-carrying part of the electrolysis unit 10, it can dissolve again, forming ions.

[0056] Among other things, cations can then enter the electrolysis cells 12 from the oxygen side and accumulate there. This process can lead to higher cell voltages and thus reduced efficiency of the electrolysis device 10. Furthermore, damaging mechanisms for the electrolysis cells 12 can be associated with these cations. For example, hydrogen peroxide formed at the electrodes can be converted into radicals upon contact with metal ions, which can chemically attack a membrane structure of the electrolysis cells 12 and thus impair the service life of the electrolysis cells 12.

[0057] FIG 3 An electrolysis device 60 is now shown, with which the aforementioned corrosion effect, which is based on FIG 2 As explained above, this can largely be avoided. The design of the electrolysis unit 60 is based on the design of the electrolysis unit 10, as previously explained using the FIG 1 and 2explained. The following explanations are therefore based on the explanations for the FIG 1 and 2 , which is why reference is made to the relevant explanations.

[0058] As from FIG 3 As can be seen, the electrolysis cells 12 are also arranged in a cell stack 54. The supply lines 24 are connected exclusively to a first end 20 of the cell stack 54, so that the first end 20 of the cell stack 54 is electrically coupled to the cell supply unit 18. The first end 20 of the cell stack 54 is electrically coupled to a negative electrical potential 34 of the electrical energy source 16. The second end 22 of the cell stack 54 is electrically coupled to a positive electrical potential 36 of the electrical energy source 16. The statements regarding the cell supply unit 18 apply essentially to the cell supply unit 18. FIG 1 and 2 .

[0059] The electrolysis cells 12 are also electrically connected in series here, so that - from an electrical point of view - there is again a series connection of all electrolysis cells 12 of the cell stack 54 - as with the cell stack 54 according to FIG 1 - is present.

[0060] This design of the electrolysis unit 60 ensures that the cell supply unit 18 has the lowest electrical potential of the entire electrolysis unit 60. This electrical potential is also connected to the negative electrical potential 34 of the electrical power source 16. The electrical power source 16 also provides the positive electrical potential 36. Between the negative and positive electrical potentials 34, 36, the electrical power source 16 provides the operating voltage for the intended operation of the electrolysis unit 60.

[0061] The cell stack 54 has cell connection lines 40, also called manifolds, for fluid coupling of the electrolysis cells 12 with the supply lines 24 connected at the first end 20. The cell connection lines 40 are integrated into the cell stack 54, so that a corresponding external supply structure is not required.

[0062] The cell connection lines 40 each have a through-opening designed such that a pressure drop across the cell connection lines 40 allows for uniform, intended operation of the electrolysis cells 12. In the present embodiment, the pressure drop is kept as small as possible so that it can be neglected for the intended operation of the electrolysis unit 60. This allows the electrolysis cells 12 to be operated at a uniform pressure, for example. For this purpose, the cell connection lines 40 have through-openings with corresponding inner diameters, so that any pressure drop during the flow of the respective fluid can be largely disregarded. Depending on requirements, the respective inner diameter can also vary for each of the cell connection lines 40.For example, the inner diameter at the first end 20 of the cell stack 54 can be larger than at the second end 22 of the cell stack 54. In particular, the cell connection lines 40 can also be integrated, at least partially, into the electrolysis cells 12. By stacking the electrolysis cells 12, the cell connection lines 40 can also be provided simultaneously.

[0063] In this embodiment, the through-holes of the cell connection lines 40 are further provided to have an inner surface coated with an anodically stable layer. This further reduces corrosion effects. For this purpose, the cell connection lines 40 are designed to be non-metallic.

[0064] At the same time, this also ensures that the cell connection lines 40 are electrically insulated. Separate electrical insulation can therefore be omitted.

[0065] The invention also makes it possible for the supply lines 24 to be designed without insulating sections, as in this embodiment. This results in particular advantages in terms of manufacturing and operation, especially with regard to safety.

[0066] It proves particularly advantageous if the cell supply unit 18, as in the present case, is FIG 3 shown to be electrically grounded by means of an earthing connection 42.

[0067] Further training according to [relevant standard / method] is particularly advantageous FIG 4 planned. FIG 4 shows in a schematic representation how FIG 3 a variant of the electrolysis device 60 according to FIG 3 , whereby the following only mentions the differences in relation to the design according to FIG 3 will be explained.

[0068] In FIG 4It is provided that the grounding 42 is not directly connected to the cell supply unit 18, but rather via a voltage source 44, by means of which the cell supply unit 18 can be supplied with an electrical potential negative relative to ground potential. For this purpose, the voltage source 44 provides an electrical voltage of approximately -1 V to approximately -0.8 V. However, this voltage can also be selected, for example, in a range of approximately -2 V to approximately zero volts.

[0069] With such an electrical voltage setting, the corrosion effect, for example in stainless steel, can be suppressed even better under maritime conditions, for example in offshore applications.

[0070] It is particularly advantageous if the counter electrode for cathodic corrosion protection is also located in the area of ​​the cell supply unit 18. The electrode provided here for grounding 42 is formed by a titanium anode coated with a mixed oxide. The titanium anode with the mixed oxide coating is electrically insulated from the cell supply unit 18 and located in a liquid phase of an oxygen separator (not shown).

[0071] Overall, the exemplary embodiments show that the invention makes it possible to reduce corrosion by connecting all supply lines 24 on the one hand to the cell supply unit 18 and on the other hand only to the first end 20 of the cell stack 54.

[0072] The grounding or massing concept of the invention largely prevents the release of metal ions. The electrodes of the active cell surfaces of the electrolysis cells 12 can therefore act as anodic counter electrodes for stray currents. Thus, undesirable corrosion can be largely avoided.

[0073] The invention is not limited to application in the electrolysis of water and can equally be used in other electrolysis processes, for example carbon dioxide electrolysis or the like.

[0074] The exemplary embodiments serve solely to illustrate the invention and are not intended to limit it.

Claims

1. Electrolysis device (60) having - a plurality of electrolytic cells (12) which are electrically connected in series and which are arranged at least partially in a stacking direction (14) one after the other in a cell stack (54), wherein the series circuit is electrically couplable to an electrical energy source (16), - a cell supply unit (18) for supplying the electrolytic cells (12) with at least one fuel during operation as intended, and - supply lines (24) attached to the cell supply unit (18) and to the cell stack (54), wherein a material of the supply lines (24) has metal, characterized in that the supply lines (24) are attached exclusively to a first end (20) of the cell stack (54), such that the first end (20) of the cell stack (54) is electrically coupled to the cell supply unit (18), wherein the first end (20) of the cell stack (54) is couplable to a negative electrical potential (34) of the electrical energy source (16).

2. Electrolysis device according to Claim 1, characterized in that the cell stack (54) has cell attachment lines (40) for fluidically coupling the electrolytic cells (12) to the supply lines (24) attached to the first end (20).

3. Electrolysis device according to Claim 2, characterized in that the cell attachment lines (40) each have a through opening which is formed in such a way that a pressure drop at the cell attachment lines (40) allows the electrolytic cells (12) to operate uniformly as intended.

4. Electrolysis device according to Claim 2 or 3, characterized in that the through opening has an inner surface which is coated with an anodically stable layer.

5. Electrolysis device according to one of Claims 2 to 4, characterized in that the cell attachment lines (40) are designed to be at least partially non-metallic.

6. Electrolysis device according to one of Claims 2 to 5, characterized in that the cell attachment lines (40) are designed to be at least partially electrically insulated.

7. Electrolysis device according to one of the preceding claims, characterized in that the supply lines (24) are formed at least partially without insulating portions.

8. Electrolysis device according to one of the preceding claims, characterized in that the cell supply unit (18) is at least indirectly electrically grounded (42).

9. Electrolysis device according to Claim 8, characterized in that the grounding (42) has a sacrificial anode and / or a voltage source (44) by means of which the cell supply unit (18) can have a negative electrical potential applied to it relative to the ground potential (42).

10. Electrolysis device according to Claim 9, characterized in that the voltage source is designed to provide an electrical voltage in a range from -2 V to zero volts.