Electrolysis device

Abstract

The invention relates to an electrolysis device (60) comprising a plurality of electrolysis cells (12) which are electrically connected in series and which are arranged one after the other at least partly in a stack direction (14), wherein the series circuit can be electrically coupled to an electric energy source (16); a cell supply unit (18) for supplying the electrolysis cells (12) with at least one operating fluid for an intended operation; and supply lines (24) connected to the cell supply unit (18) and to opposite ends (20, 22) of electrolysis cells (12) arranged one after the other. According to the invention, a negative electric potential (34) of the electric energy source (16) can be electrically coupled to an electric reference potential of the cell supply unit (18).

Description

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

[0002] Electrolysis cells, which convert chemical substances into other chemical substances using electricity, are well known in the art. Typically, a chemical reaction, i.e., a substance transformation, is induced using an electric current. This process is called electrolysis. A well-known and widely used form of electrolysis is water electrolysis. In water electrolysis, water is split into its components, namely hydrogen and oxygen, using an electric current. However, other substances, such as carbon dioxide and the like, can also be subjected to electrolysis.

[0003] Typically, these are fluid substances that can be supplied via appropriate supply lines to the electrolysis cells where the actual electrolysis takes place. The electrolysis products are often also in fluid form and are removed from the electrolysis cells via additional supply lines. The supply lines are usually connected to a cell supply unit, which serves to supply the electrolysis cells with the respective substances or at least one operating material for their intended operation. "Supply" here therefore means not only supplying the operating material or the material to be electrolyzed, but also removing the respective electrolysis product.

[0004] The production of hydrogen is proving particularly interesting industrially, especially since hydrogen can be a versatile energy carrier. Hydrogen can be produced using an electrolysis device, also called an electrolyzer, using electrical energy generated from renewable sources. One possibility for producing hydrogen is to use an electrolysis device whose electrolysis cells are based on proton exchange membranes (PEMs). The principle of a PEM-based electrolysis device or PEM-based electrolysis cell is known in the art, which is why further explanations will be omitted. An electrolysis cell for producing hydrogen and oxygen from water is disclosed, for example, 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] Generic electrolysis devices typically comprise a plurality of electrolysis cells, which are usually electrically connected in series. The resulting series circuit is electrically coupled to an electrical energy source that provides a suitable electrical voltage, allowing the electrolysis cells to implement the intended electrochemical conversion process.

[0006] Furthermore, the electrolysis cells are arranged one after the other in a stacking direction, forming a cell stack. This stacked arrangement allows the consecutively arranged electrolysis cells to be directly electrically connected, thus significantly reducing the need for separate electrical connections between the electrolysis cells.

[0007] Furthermore, a supply line system (manifold) is provided within the cell stack, which serves to supply the at least one operating medium to and from the electrolysis cells. The operating medium can comprise, for example, the supplied fluid, for example water, and / or the reaction product, for example hydrogen and oxygen. The cell stack is generally operated with a specific electrolysis power so that the electrical current is as small as possible, but the electrical voltage is as high as possible. This is achieved by suitably stacking the electrolysis cells in the cell stack. This allows the 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 for this purpose can be connected to respective opposite ends of the cell stack. A cell stack can contain a plurality of electrolysis cells, for example more than 100 electrolysis cells, in particular several hundred electrolysis cells, but preferably no more than about 400 electrolysis cells. During electrolysis of water to hydrogen and oxygen, the electrical voltage across each of the electrolysis cells is approximately 1.5 V to 2.5 V. This results in a corresponding electrical voltage across the cell stack, so that the electrical voltage across the cell stack often exceeds 100 V and can even amount to several hundred volts.

[0009] In addition to the cell stack, the electrolysis system includes other components, such as pumps, heat exchangers, and separation tanks, which are required for the proper operation of the electrolysis system or the electrolysis cells. These components are summarized here by the cell supply unit, which supplies the electrolysis cells with at least one operating fluid for proper operation.

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

[0011] A correspondingly high electrical voltage occurs between the ends of the cell stack or the consecutively arranged electrolysis cells. The supply lines, which are usually made of metal, therefore require electrically insulating sections to prevent a highly conductive connection between the ends of the consecutively arranged electrolysis cells and thus between the electrical connections of the electrical energy source.

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

[0013] In order to reduce this problem, it is known in the art to determine a specific electrical conductivity of the

[0014] The goal is to keep the water flow as low as possible and to kinetically inhibit corrosion by maintaining the longest possible insulation distance or by reducing the cross-section in the area of ​​the respective insulating section, thus spreading the effect over time. However, corrosion cannot fundamentally be prevented in this way. In particular, the constant, albeit low, electrical conductivity of water, especially within the insulation gap formed by the insulating section, leads to stray currents in the water, especially within the insulation gap. As a result, the problem of corrosion persists.

[0015] The invention is based on the object of reducing the aforementioned corrosion problem.

[0016] As a solution, the invention proposes an electrolysis device according to independent claim 1.

[0017] Advantageous further training results from features of the dependent claims.

[0018] With regard to a generic electrolysis device, the invention proposes, in particular, that a negative electrical potential of the electrical energy source be electrically coupled to an electrical reference potential of the cell supply unit. During operation of the electrolysis device, the negative electrical potential of the electrical energy source is thus electrically coupled to the electrical reference potential of the cell supply unit.

[0019] The invention is based, among other things, on the idea that the inventive design of the electrolysis device can ensure that preferably the cell supply unit, and thus also the end of the cell stack formed by the successively arranged electrolysis cells, which is connected to the negative electrical potential of the electrical energy source, has the lowest electrical potential of the electrolysis device. This end of the cell stack is also referred to below as the first end.

[0020] The electrical connection can be realized by connecting the first end of the cell stack to the electrical reference potential of the cell supply unit by means of an electrical line. The electrical reference potential of the cell supply unit can, for example, be a ground potential of the cell supply unit. The electrical reference potential of the cell supply unit can, for example, be directly or indirectly electrically coupled to a ground potential. Furthermore, it can of course also be provided that the supply lines are formed at least partially from an electrically conductive material. In particular, a material of the supply lines can comprise metal.This makes it possible to provide an electrically conductive connection independently of an electrical line, even by means of at least one of the supply lines, if the at least one of the supply lines provides electrical conductivity - like the electrical line - over its entire longitudinal extent.

[0021] It goes without saying that this can only apply to the supply lines connected to the first end of the cell stack. At least the supply lines connected to the second end of the cell stack, opposite the first end of the cell stack, have an insulating section, thus preventing an electrical connection of the second end of the cell stack to the electrical reference potential of the cell supply unit.

[0022] If the electrical connection is realized by means of an electrical cable, all supply lines can have respective insulating sections, especially if they are primarily made of metal. However, the supply lines can also be made of an electrically insulating material.

[0023] In particular, the sections of the supply lines facing the cell supply unit up to the respective insulating sections, if present, do not need to have an electrical potential that is lower than the electrical potential, in particular the electrical reference potential, of the cell supply unit. This largely prevents corrosion in the area of ​​the supply lines between the respective insulating sections, if present, and the cell supply unit. The corrosion problem can therefore be shifted to the opposite side of the respective electrical insulating section, in which area a corresponding supplementary treatment can be provided in order to largely avoid or even completely prevent the corrosion here as well.

[0024] This can be achieved, among other things, by ensuring that the consecutively arranged electrolysis cells are no longer potential-free with respect to the cell supply unit. Instead, the inventive design ensures that the cell supply unit always provides the lowest electrical potential in the electrolysis device. The consecutively arranged electrolysis cells of the cell stack remain electrically connected in series.

[0025] The design according to the invention therefore makes it possible, among other things, to reduce the corrosive effect because the conditions detrimental to the corrosive effect 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 conducted through the respective supply line, particularly if it is water, in the prior art. This can lead to the release of hydrogen and hydroxide ions. The invention makes it possible to reduce the conditions relevant to the corrosive effect, namely in particular the hydroxide ions. Preferably, the hydroxide ions can be at least partially processed or consumed in the cell stack by the electrolysis cells arranged there. They are therefore no longer available for the undesirable corrosive effect.It is therefore particularly advantageous if the insulating sections are arranged as close as possible to the respective ends. Overall, the invention thus makes it possible to reduce or even completely eliminate the undesirable corrosion effect.

[0026] The electrolysis cells can, for example, be arranged consecutively in a single cell stack. Preferably, the electrolysis cells are electrically connected in series within the cell stack. The opposite ends of the cell stack, namely the first and second ends, can be connected to the respective electrical potentials of the electrical energy source. They can, for example, be connected directly to the electrical energy source. However, they are preferably connected to the electrical energy source via a control unit so that the function of the electrolysis cells can be adjusted as needed.

[0027] The electrical energy source can, for example, be any voltage or current source capable of providing sufficient power to carry out the electrolysis 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.

[0028] The supply lines have a through-opening with a suitable inner diameter or cross-section in order to be able to supply the respective operating material to the electrolysis cells with as little loss as possible and / or to discharge it from the respective electrolysis cells or the partial stacks with as little loss as possible.

[0029] According to a further development, it is proposed that a material of the supply lines comprises metal, wherein the electrolysis cells are arranged in at least two partial stacks, wherein each of the at least two partial stacks is connected to the cell supply unit by means of at least one first supply line connected to the cell supply unit and to a first end of the respective partial stack and at least one second supply line connected to the cell supply unit and to a second end of the respective partial stack opposite the first end in the stacking direction, wherein the first supply line connected to the first end of the partial stack that can be coupled to a negative electrical potential of the electrical energy source is electrically conductively connected to the cell supply unit and all other supply lines have respective electrical insulating sections.

[0030] In this refinement, the electrolysis cells of the sub-stacks are preferably still connected in series, with the respective sub-stacks also being connected in series as a whole. With regard to the connection to the cell supply unit, however, the sub-stacks are essentially connected in parallel for fluidic purposes. As a result, a stack voltage at the respective opposite ends of each sub-stack can naturally be significantly lower than the electrical voltage to be provided by the electrical energy source across the complete series connection. At the same time, the corrosive effect described above can be reduced or largely avoided.

[0031] The electrical insulating sections of the supply lines are also designed accordingly and can, for example, be made of a suitable material that can be mechanically firmly connected to the respective supply line. For example, it can be an annular section that is arranged at a respective end of a respective supply line. Furthermore, the insulating section can of course also be integrated into the supply line, so that the supply line has two supply line sections that are electrically insulated from one another and separated from one another by the insulating section. These units formed in this way are preferably connected to one another in a fluid-tight manner, wherein a substantially constant internal cross-section is preferably provided for the respective operating fluid.

[0032] The material for the electrical insulating section can be, for example, a plastic, a ceramic, or even a metal oxide such as titanium dioxide, aluminum oxide, and / or the like. Furthermore, a composite material can also be provided, which can be formed, for example, from a plastic that can be fiber-reinforced, for example. Of course, almost any combination of these can also be provided, which are preferably selected such that a chemical reaction with the respective operating fluid to be conveyed is essentially avoided.

[0033] The material of the supply line comprises at least metal. The metal can be steel, for example, particularly stainless steel. Of course, another metal, such as titanium or the like, can also be used. Of course, appropriate metal alloys can also be provided.

[0034] According to a further development, it is proposed that an electrical insulation layer be arranged on the inside of the supply line at an end of the respective insulation section facing the respective end of the respective partial stack. The insulation layer formed here makes it possible to further reduce the corrosion effect. The electrical insulation layer can be formed, for example, by a plastic, a ceramic, or the like, which is arranged on the inside of the respective supply line in the respectively predetermined area. This allows the surface area available for corrosion effects on the inside of the supply line to be further reduced.

[0035] It proves particularly advantageous if the electrical insulation layer extends from the respective insulating section to the respective end of the respective partial stack. This essentially completely prevents corrosion on the supply line side. This refinement therefore makes it possible to further improve the effect of the invention.

[0036] It is further proposed that the electrical insulation layer have a coating made of an insulating material. The coating can be formed, for example, from a plastic, a paint, a combination thereof, and / or the like. The coating can be applied to the inside of the supply line in the area of ​​the through-opening before installation on the respective supply line. The coating only needs to extend to the electrical insulation section. This allows for effective corrosion protection with limited effort.

[0037] It is also proposed that the electrical insulation layer be made of a corrosion-resistant metal-containing material. This creates a very robust surface that can be easily connected to the supply line.

[0038] The corrosion-resistant metal-containing substance is preferably a metal oxide. The metal oxide can be, for example, a ceramic material, titanium dioxide, aluminum oxide, and / or the like.

[0039] According to a further development, it is proposed that the respective ends of the partial stacks facing the respective insulating sections be electrically insulated from the electrolysis cells. This can largely prevent corrosion in the area between the insulating section and the respective end of the partial stack. The effect of the invention can thus be further improved.

[0040] It is further proposed that the cell supply unit is at least indirectly electrically grounded, i.e. the cell supply unit can be connected to an earthing system. By means of the earthing, the cell supply unit and the supply lines electrically coupled to it can be connected to a predetermined reference potential. As a result, the negative potential of the electrical energy source, which is electrically coupled to the cell supply unit via the supply lines, can also be at least indirectly grounded. Unlike in the prior art, the cell stack formed from the partial stacks is therefore at a defined electrical potential with respect to the earth potential and thus no longer has a floating potential. In this way, a defined electrical potential difference or electrical voltage can be achieved at the respective electrically insulating sections.This allows to further improve the reliability of the function of the invention.

[0041] Furthermore, it is proposed that the grounding system comprise a sacrificial anode and / or a voltage source, by means of which the cell supply unit can be subjected to an electrical potential that is negative relative to the ground potential. This makes it possible to achieve "cathodic corrosion protection." If a voltage source is used, the negative electrical potential of the voltage source can be electrically connected to the cell supply unit and to the supply lines connected to it. The negative electrical potential of the voltage source is preferably also correspondingly grounded. For the corrosion protection implemented in this way to function effectively, the voltage source can provide an electrical voltage in a range from approximately -2 V to approximately zero volts with respect to the ground potential. It is particularly advantageous if this electrical voltage is selected in a range from approximately -1 V to approximately -0.8 V.With an electrical voltage selected within this range, corrosion of stainless steel, for example, can be prevented even under maritime conditions, especially in offshore applications. In particular, external corrosion phenomena can be reduced or prevented.

[0042] To equally reduce or prevent internal corrosion phenomena, it can preferably be provided that a further electrode in the manner of a counter electrode for cathodic corrosion protection is arranged in the region of the cell supply unit. The internal corrosion phenomenon refers in particular to corrosion effects within the electrolysis device, especially within the cell supply unit. For example, this can be a titanium electrode, or titanium anode, which can be coated with a mixed oxide. The anode formed in this way is preferably arranged in a liquid phase of an oxygen separation tank of the cell supply unit.

[0043] It is particularly advantageous for the sub-stacks to be connected in parallel to the cell supply unit for power supply purposes. This ensures a good supply of at least one operating fluid to the sub-stacks. The supply can include adding or removing the operating fluid or substances generated during electrolysis.

[0044] Supply structures formed in the sub-stacks or electrolysis cells can serve as internal insulation distances. Materials used, for example, to contact the water to be electrolyzed within a respective sub-stack, except in the area of ​​the respective active cell surfaces of the respective electrolysis cells, can meet at least one of the following three requirements: The materials are non-metallic; metals with electrical potential are coated with an oxidation-stable layer such as titanium dioxide, a polymer, or the like; non-coated metals are not electrically bonded, i.e., essentially electrically potential-free, in particular floating.

[0045] The invention thus enables the electrodes of the active cell surfaces of the electrolysis cells to act as anodic counterelectrodes. This allows, for example, minimally more oxygen to be formed at the respective anodes of the electrolysis cells and minimally less hydrogen to be produced at the respective cathodes of the respective electrolysis cells. However, these changes during electrolysis do not significantly affect the efficiency and safety of the electrolysis device. Rather, the advantage of the invention outweighs the risk of foreign ions being released from metallic components due to stray currents.

[0046] The designs and advantages specified for each of the partial stacks also apply, in principle and in a correspondingly adapted manner, to the entire cell stack if no partial stacks are formed.

[0047] The features and combinations of features mentioned above in the description as well as the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the respective combination specified but also in other combinations without departing from the scope of the invention.

[0048] The exemplary embodiments explained below are preferred embodiments of the invention. The features and combinations of features specified in the description above, as well as the features and combinations of features mentioned in the following description of exemplary embodiments and / or shown alone in the figures, can be used not only in the respective combinations specified, but also in other combinations. Thus, embodiments are also encompassed by the invention or considered disclosed that are not explicitly shown and explained in the figures, but which emerge and can be produced from the explained embodiments through separate combinations of features.The features, functions, and / or effects illustrated by the exemplary embodiments may, in and of themselves, represent individual, independently considered features, functions, and / or effects of the invention, each of which also further develops the invention independently of one another. Therefore, the exemplary embodiments are intended to encompass combinations other than those in the illustrated embodiments. Furthermore, the described embodiments may also be supplemented by further features, functions, and / or effects of the invention already described.

[0049] In the figures, the same reference symbols denote the same features or functions.

[0050] They show: FIG 1 shows a schematic block diagram of an electrolysis device for electrolyzing water; FIG 2 shows a schematic sectional view of a supply line of the electrolysis device according to FIG 1 in the area of ​​an insulating section; FIG 3 a schematic block diagram such as FIG 1 a further electrolysis device for electrolyzing water, in which a cell stack is divided into four sub-stacks according to a first embodiment; and FIG 4 a schematic representation of how FIG 3 for a second embodiment of the electrolysis device.

[0051] FIG 1 shows a schematic block diagram of an electrolysis device 10 comprising a cell stack 54 comprising a plurality of electrolysis cells 12 arranged consecutively in a stacking direction 14. The electrolysis cells 12 serve, in this case, to electrochemically decompose water into its constituents, oxygen and hydrogen. The electrolysis device 10 therefore serves, in this case, to generate hydrogen and oxygen from water.

[0052] The electrolysis cells 12 are arranged directly adjacent to one another, so that the respective electrodes of the adjacent electrolysis cells 12 can make electrical contact. It is provided that an anode of a first of the electrolysis cells 12 electrically contacts a cathode of the immediately adjacent second electrolysis cell 12. As a result, the electrolysis cells 12 are electrically connected in series.

[0053] Via an internal supply structure of the cell stack 54 (not shown in detail), the electrolysis cells 12 are supplied with water to be electrolyzed, on the one hand, and with outlets for the produced substances, hydrogen and oxygen, on the other hand. This supply is designed to be connectable to opposite ends 20, 22 of the cell stack 54.

[0054] Furthermore, an electrical energy source 16 is connected to the ends 20, 22 via an electrical line 52, which in the present case provides a suitable electrical voltage with a suitable electrical power, so that the electrolysis cells 12 can be supplied with sufficient electrical energy for the intended operation.

[0055] The electrolysis device 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 materials, which in this case relate to the supply of water and the removal of hydrogen and oxygen. The cell supply unit 18 comprises several components that are required for the intended operation of the electrolysis device 10, such as pumps, heat exchangers, separation tanks, 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 fluidically couple the supply structure of the cell stack 54.The supply lines 24 are made of a metal such as stainless steel.

[0056] To prevent a short circuit between the ends 20, 22 of the cell stack 54 due to the metal supply lines 24, each of the supply lines 24 has an electrical insulation section 38. This ensures that the ends 20, 22 are electrically insulated from the cell supply unit 18 and thus also electrically insulated from each other. The supply lines 24 are located outside the cell stack 54.

[0057] In the present case, the insulating sections 38 are essentially formed from an electrical insulating material, which may be, for example, a suitable ceramic material or also a suitable plastic or composite material. FIG 2 shows a schematic sectional view of one of the supply lines 24 from FIG 1 in the area of ​​the isolation section 38. In FIG 2 The supply line 24 is shown with a first region 58 facing the end 22 of the cell stack 54, whereas an opposite second region 56 faces the cell supply unit 18. The regions 56 and 58 are electrically separated from one another 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 corresponding fluid, which in this case is water, can be conducted.

[0058] Due to the electrical voltage applied to the electrical insulation section 38, corrosion takes place in an area 64. This can be considered to be due to the fact that in the area of ​​a transition from the area 56 to the electrical insulation section 38, negative hydroxide ions are formed by electron absorption from the metal of the wall of the supply line 24 into the water flowing in the inner diameter 62, which are guided to the area 58 due to the electric field and there react electrochemically with the metal of the wall of the supply line 24, as shown in FIG 2 This causes the wall of the supply line 24 to corrode in this area 64. This is undesirable.

[0059] For this type of corrosion, it should be borne in mind that, as a rule, a direct voltage in the range of several hundred volts can be applied across the electrical insulating sections 38 during normal operation. This can result in an excess of electrons in area 56 of the electrical insulating section 38 and an electron deficiency in area 58. Due to the magnitude of the electrical voltage at the electrical insulating section 38, from a thermodynamic point of view, electrode reactions take place, as previously explained. Although the corrosion effect can be spread out over time, i.e. kinetically inhibited, by reducing the electrical voltage, it cannot be completely prevented. Even extending the insulation distance by means of the electrical insulating section 38 or reducing the inner diameter 62 can only inhibit the corrosion effect in terms of its effectiveness, but cannot prevent it.

[0060] In area 56, the hydrogen produced can be dissolved in the water or in the form of tiny bubbles and carried away with the water. The quantities produced are generally so small that the hydrogen itself does not cause any adverse effects.

[0061] However, this is not true for the hydroxide ions, which 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 electrically 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 decomposition is shown 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 virtually any other metallic material.

[0062] In addition to the release of iron, other metals that may be present in the steel can also be dissolved. This can result in cations being formed. Due to their positive charge, the metal cations tend to migrate in the opposite direction to the hydroxide ions. This can lead to what is known as rouging between the metal cations, particularly iron ions, and the hydroxide ions. Rouging refers to extremely fine iron-containing particles that can spread throughout the supply lines 24 and the components of the electrolysis device 10. They can be observed primarily in the supply lines 24, which also carry hydrogen. If this rouging reaches the oxygen-carrying part of the electrolysis device 10, the rouging can dissolve again to form ions.

[0063] 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 a decrease in the 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 on the electrodes can be converted into radicals upon contact with metal ions, which can chemically attack the membrane structure of the electrolysis cells 12 and thus impair the service life of the electrolysis cells 12.

[0064] FIG 3 now shows an electrolysis device 60 with which the aforementioned corrosion effect, which is based on FIG 2 The following explanations are based on the explanations for the FIG 1 and 2, which is why we refer to the relevant comments.

[0065] As from FIG 3 As can be seen, the electrolysis cells 12 are arranged in four partial stacks 26, 28, 30, 32. Each of the four partial stacks 26, 28, 30, 32 is connected to the cell supply unit 18 by means of two first supply lines 24 connected to the cell supply unit 18 and to a first end of the respective partial stack 26, 28, 30, 32, and two second supply lines 24 connected to the cell supply unit 18 and to a second end 22 of the respective partial stack 26, 28, 30, 32 opposite the first end 20 in the stacking direction 14. The statements regarding the FIG 1 and 2 .

[0066] The first supply line 24, which is connected to the first end 20 of the partial stack 26 coupled to a negative electrical potential 34 of the electrical energy source 60, is electrically connected to the cell supply unit 18. As a result, precisely this first end 20 of the partial stack 26 is electrically directly connected to the cell supply unit 18. All other supply lines 24 have respective electrical insulating sections 38.

[0067] In the present case, the number of electrolysis cells 12 of the sub-stacks 26, 28, 30, 32 is the same for all sub-stacks 26, 28, 30, 32. However, depending on requirements, this may also be chosen differently in other embodiments without departing from the spirit of the invention.

[0068] The partial stacks 26, 28, 30, 32 are in turn electrically connected in series, so that - from an electrical point of view - a series connection of all electrolysis cells 12 of the partial stacks 26, 28, 30, 32 - as in the cell stack 54 according to FIG 1 - is present.

[0069] This design of the electrolysis device 60 ensures that the cell supply unit 18, from an electrical perspective, has the lowest electrical potential of the entire electrolysis device 60. This electrical potential is further connected to the negative electrical potential 34 of the electrical energy source 16. The electrical energy source 16 also provides the positive electrical potential 36. Between the negative and positive electrical potentials 34, 36, the electrical energy source 16 provides the operating voltage for the intended operation of the electrolysis device 60.

[0070] In the present embodiment, it is further provided that an electrical insulation layer is formed on the respective insulating section ends 40 of the respective insulating sections 38 facing the respective ends 20, 22 of the respective partial stacks 26, 28, 30, 32 on the inside of the supply line. In this case, this layer is formed by a coating of an insulating material. The insulating material is, for example, a suitable plastic. Alternatively or additionally, however, a corrosion-resistant metal-containing material can also be provided, for example, a metal oxide or the like, in particular, for example, a ceramic material.

[0071] Furthermore, it can be provided that the respective ends 20, 22 of the partial stacks 26, 28, 30, 32, which face the respective insulating sections 38, are designed to be electrically insulated from the electrolysis cells 12. This can further reduce the corrosion effect. It is particularly advantageous if the cell supply unit 18, as shown in the present case in FIG 3 shown, is electrically grounded by means of an earthing 42.

[0072] Further training according to FIG 4 provided. FIG 4 shows in a schematic representation how FIG 3 a variant of the electrolysis device 60 according to FIG 3 , whereby in the following only the differences are a reference to the design according to FIG 3 be explained.

[0073] In FIG 4It is provided that the grounding 42 is not provided directly on the cell supply unit 18, but rather by using a voltage source 44, by means of which the cell supply unit 18 can be subjected to an electrical potential that is negative relative to the 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 from approximately -2 V to approximately zero volts.

[0074] With such an electrical voltage, the corrosion effect, for example in stainless steel, can be suppressed even better under maritime conditions, for example in offshore applications.

[0075] It proves particularly advantageous if the counter electrode for cathodic corrosion protection is also arranged in the area of ​​the cell supply unit 18. The electrode provided here for grounding 42 is formed in this case by a titanium anode coated with a mixed oxide. The titanium anode with the mixed oxide coating is arranged in a liquid phase of an oxygen separation tank (not shown) and is electrically insulated from the cell supply unit 18.

[0076] Overall, the embodiments show that the invention can achieve that the corrosion can be reduced by forming a plurality of partial stacks 26, 28, 30, 32 of the electrolysis cells 12, which are all still electrically connected in series, but are separately connected to the cell supply unit 18 via their own supply lines 24.

[0077] 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 counterelectrodes for stray currents. Thus, unwanted corrosion can be largely avoided.

[0078] The invention is not limited to the application in the electrolysis of water and can equally be used in other electrolyses to be carried out, for example carbon dioxide electrolysis or the like.

[0079] The embodiments serve solely to explain the invention and are not intended to limit it.

Claims

1. Electrolysis device (60) having - a plurality of electrolysis cells (12) that are electrically connected in series and are arranged successively at least partly in a stack direction (14), wherein the series connection is electrically couplable to an electrical energy source (16), - a cell supply unit (18) for supplying the electrolysis cells (12) for operation as intended with at least one operating material, and - supply conduits (24) connected to the cell supply unit (18) and to opposite ends (20, 22) of the successively arranged electrolysis cells (12), characterized in that a negative electric potential (34) of the electrical energy source (16) is electrically couplable to an electric reference potential of the cell supply unit (18).

2. Electrolysis device according to Claim 1, characterized in that a material of the supply conduits (24) includes metal, wherein the electrolysis cells (12) are arranged in at least two substacks (26, 28, 30, 32), each of the at least two substacks (26, 28, 30, 32) being connected to the cell supply unit (18) by means of at least one first supply conduit (24) connected to the cell supply unit (18) and to a first end (20) of the respective substack (26, 28, 30, 32) and at least one second supply conduit (24) connected to the cell supply unit (18) and to a second end (22) of the respective substack (26, 28, 30, 32) opposite the first end (20) in the stack direction (14), wherein that first supply conduit (24) which is connected to the first end (20) of that substack (26) that is couplable to a negative electric potential (34) of the electrical energy source (16) is electrically conductively connected to the cell supply unit (18) and all other supply conduits (24) have respective electrical insulating sections (38).

3. Electrolysis device according to Claim 2, characterized in that an electrical insulation layer is arranged on the inside of the supply conduit on an insulating section end (40) of the respective insulating section (38) facing the respective end (20, 22) of the respective substack (26, 28, 30, 32).

4. Electrolysis device according to Claim 3, characterized in that the electrical insulation layer extends from the respective insulating section (38) up to the respective end (20, 22) of the respective substack (26, 28, 30, 32).

5. Electrolysis device according to Claim 3 or 4, characterized in that the electrical insulation layer has a coating formed from an insulation material.

6. Electrolysis device according to any of Claims 3 to 5, characterized in that the electrical insulation layer includes a corrosion-resistant metal-containing substance.

7. Electrolysis device according to any of the preceding claims, characterized in that the respective ends (20, 22) of the substacks (26, 28, 30, 32) that face the respective insulating sections (38) are electrically insulated from the electrolysis cells (12).

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

9. Electrolysis device according to Claim 8, characterized in that the earthing (42) has a sacrificial anode and / or a voltage source (44), by means of which an electric potential that is negative with respect to the earth potential (42) is applicable to the cell supply unit (18).

10. Electrolysis device according to any of Claims 2 to 9, characterized in that the substacks (26, 28, 30, 32) are connected in parallel in terms of supply to the cell supply unit (18).

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