DE102023201992A1 - Stack arrangement for electrochemical energy conversion - Google Patents

Abstract

The invention relates to a stack arrangement (12) for electrochemical energy conversion with a number of cells (14) stacked one above the other, wherein the cells (14) each have a membrane (16) to which a cathode functional surface (20) and an anode functional surface (22) are assigned, and bipolar plates (24) and/or monopolar plates (48) and/or polar plates (49) are arranged between the cells (14). Within the stack arrangement (12) there are either sub-stacks (74, 76, 78) with a number of cells (14) or cells (14) arranged in reverse order (105) with respect to one another, or a combination of both, wherein an electrochemically active surface (18) of the cells (14) is divided into several galvanically isolated segments (62, 64, 66, 68). Furthermore, the invention relates to the use of the stack arrangement (12) for producing hydrogen in an electrolysis device or a fuel cell for converting hydrogen into electrical current and to the use of the stack arrangement (12) in electrochemical systems for converting gaseous or liquid media into electrical current and to the use of the stack arrangement (12) in a redox flow system.

Description

Technical area

The invention relates to at least one stack arrangement for electrochemical energy conversion, which is formed from several cells stacked one above the other, wherein the cells each have a membrane to which a cathode and an anode are assigned and plates, monopolar plates or bipolar plates are provided between the cells in the at least one stack arrangement. Furthermore, the invention relates in particular to the use of the stack arrangement for generating H ₂ in an electrolysis device or a fuel cell for converting H ₂ into electrical current or in electrochemical systems for converting gaseous or liquid media into electrical current or in redox flow systems.

State of the art

Stack arrangements, in particular for electrolysis, for example the subgroups PEM stack arrangements (polymer electrolyte membrane or proton exchange membrane, AEM stack arrangements (anion exchange membrane), SOC stack arrangements (solid oxide cell) and AEL stack arrangements (alkaline electrolysis), are usually designed as vertical stack arrangements of individual cells. The individual cells are stacked vertically on top of each other. The core of an individual cell in the stack arrangement is a membrane that is provided with electrodes for anode and cathode on its top and bottom. A membrane designed in this way is, for example, the CCM (catalyst coated membrane), but other variants such as CCS (catalyst coated substrate) are also conceivable. When an electrical voltage is applied, water supplied in the case of electrolysis is broken down into the components H ₂ and O _2. To prevent the product gases from mixing, a seal is provided on both sides of the membrane. which can also take on the function of a frame and which also ensures the connection to the corresponding media channels and/or contains them. The voltage required per cell results from the thermoneutral voltage and losses of the electrochemical process as well as the existing contact resistances. Typical voltage values per cell are in the range of 1.5 volts to 2.3 volts.

By stacking several identically constructed cells, i.e. the stack arrangement, and an electrical series connection, for example by means of a monopolar and/or bipolar plate, the voltage of a stack arrangement increases to n · cell voltage, where n = number of cells.

The current remains the same in such an electrical series connection; with an increased cell area, the stack arrangement current increases proportionally. The stack arrangement voltage is limited by an upper limit, which is determined by the maximum number of stackable cells per stack arrangement of typically less than 300 cells due to mechanical limitations, so that usually only a stack arrangement voltage of < 600 volts can be achieved.

The demand for electrolysis capacity is increasing, while the achievable hydrogen production costs (LCOH, Levelized Cost of Hydrogen) are a key driver for successful distribution. The efficiency of electrolysis plants is crucial for increasing the performance of electrolysis, in particular the achievable efficiencies along the process chain, including, for example, power electronics.

For larger solar parks, the use of direct current systems with the highest possible voltage is increasingly being sought, and wind turbines in the electrolysis environment will also be using direct current distribution with a high voltage in the future (for example offshore wind turbines). The transport of high power is generally more advantageous for the efficiency of the transmission at high voltages and correspondingly low currents, since the current is quadratically included in the power loss. Smaller cable cross-sections therefore save weight and costs.

For the process chain in electrolysis plants, it can be deduced that the highest possible voltages should be aimed for, for example by exploiting the low-voltage limit, which is 1500 volts. But even above the low-voltage limit, a medium-voltage level of, for example, 10 kV up to a maximum of approx. 54 kV direct current is conceivable as a direct supply source.

Such a voltage level can and is usually achieved by connecting several stack arrangements in series. However, such an electrical series connection involves risks if, for example, one or more stack arrangements (stacks) fail and the entire circuit is no longer closed and/or the minimum required voltage is not reached when stacks are bridged. Furthermore, relatively large busbars are required to handle the currents that arise, which are material-intensive and therefore expensive. At higher voltages, the higher insulation required can tion strength can usually be achieved more cheaply in comparison.

Description of the invention

According to the present invention, a stack arrangement for electrochemical energy conversion is proposed, with a number of cells stacked one above the other, wherein the cells each have a membrane to which a cathode and an anode are assigned and polar plates, bipolar plates and/or monopolar plates are arranged between the cells, wherein the electrochemically active surfaces of the cells are divided into several galvanically separated segments. Within the stack arrangement, either sub-stack arrangements with a number of cells or cells are arranged in reverse order with respect to one another within a cell layer and are electrically connected in series.

By arranging sub-stack arrangements or cells in reverse order, i.e. with different polarity with respect to the arrangement of the positive and negative poles, as proposed according to the invention, a significant increase in the voltage can be achieved, which is represented by the stack arrangement proposed according to the invention. In particular, when the sub-stack arrangements or the cells formed within the stack arrangement are electrically connected in series, a significant increase in the stack arrangement voltage of up to 1.5 kV (low voltage) or more (medium voltage) can be achieved.

In an advantageous development of the stack arrangement proposed according to the invention, the sub-stack arrangements with a number of cells or sub-cells are electrically connected in series at the cell level.

In an advantageous development of the stack arrangement proposed according to the invention, for example, the sub-stack arrangements are electrically connected in series via segmented monopolar plates, which are used as upper end plates and/or lower end plates.

The stack arrangement proposed according to the invention in the field of electrolysis is further characterized in that the media supply comprises at least one H ₂ O supply or feed line, at least one H ₂ O and/or O ₂ outlet and at least one H ₂ outlet.

In an advantageous development of the stacking arrangement proposed according to the invention, media connections are spatially shown from the connection field of the electrical contacts of the stacking arrangement with negative pole and positive pole, in particular in the area of the lower end plate of the stacking arrangement.

Furthermore, the stack arrangement proposed according to the invention can have media connections for sub-stack arrangements, which are returned and/or collected outside the stack arrangement to improve the insulation properties. By arranging the sub-cells or sub-stacks in an alternating sequence, a reduction in the number of busbars required can be achieved, since this function is taken over by the segmentation of the monopolar plate or bipolar plate. At the same time, the alternating arrangement requires different media areas within a cell layer. The stack arrangement according to the invention enables the required media areas to be reduced, for example to just two media areas, by spatially offsetting the oppositely polarized sub-cells or sub-stacks. This is accompanied by a reduction in the required sealing surface. In an alternative embodiment, several media areas per cell layer are possible. This can be achieved according to the invention by increasing the number of media supply lines or discharge lines, which can take the required insulation distances into account.

Furthermore, the stack arrangement proposed according to the invention comprising sub-stack arrangements and/or sub-cells arranged in reverse sequence within a stack arrangement can achieve a reduction in construction costs.

The invention further relates to a cell for electrochemical energy conversion with an electrochemically active surface, wherein the electrochemically active surface is divided into several galvanically separated segments. The stack arrangement proposed according to the invention can advantageously be constructed from such cells, preferably manufactured as sheet metal components, in a corresponding height or taking into account spatial requirements.

In a further advantageous embodiment of the stack arrangement proposed according to the invention, the electrochemically active surface of the cells in the membrane is divided into several arbitrarily configured segments in a one-dimensional division, for example into at least one segment, or in a multi-dimensional division into at least two segments. Furthermore, the solution proposed according to the invention can be used for sub-stack arrangements in the reverse sequence or by arranging individual cells in reverse order, a meandering current path can be achieved, for example from the top to the bottom or a horizontal or spirally extending current path within the stack arrangement. This allows the electrical path within the stack arrangement to be minimized, as well as the parasitic losses.

In a further advantageous manner, in the stack arrangement proposed according to the invention, sub-cells can be formed at the cell level, which have inverted stacked cell sections. This results in a smaller voltage difference between the sub-cells within a cell level and to the adjacent cell level. The electrical connection is only made between two sub-cells at a time, without the need for external busbars, but for example only by insulating the areas of the mono- and/or bipolar plates. This also results in simplified assembly of the stack arrangement due to a reduced number of parts or components. The stack arrangement proposed according to the invention can advantageously comprise sub-cells that can be electrically contacted via segmented polar plates or connected in series. A cell for electrochemical energy conversion with an electrochemically active surface is advantageously used, wherein the electrochemically active surface is divided into several galvanically separated segments. These arbitrarily shaped segments can comprise one to four segments in a one-dimensional division or at least two segments in a multi-dimensional division, wherein the segments have the same electrochemically active surface or approximately the same electrochemically active surface.

The segments are galvanically separated by a galvanic subdivision between adjacent cathode functional surfaces or anode functional surfaces and porous transport layers or gas diffusion layers. The galvanic subdivision can be carried out at the level of the anode functional surface and/or the cathode functional surface by interrupting the coating and/or passivation. Furthermore, the galvanic subdivision at the level of the porous media transport layers, namely the gas diffusion layer and/or the porous transport layer, can be provided by an electrically insulating intermediate layer or porous stabilization layer. The electrically insulating intermediate layer stabilizes the membrane of the cells, can comprise passivated carbon foam or can be designed as at least one plastic component with an integrated flow field.

The galvanic separation can take place on the polar plate, formed by monopolar plates and/or bipolar plates, using an IMS (Isolated Metal Substrate) process and/or a local passivation of the material of the polar plate, for example the monopolar plate and/or the bipolar plate. Different media areas can be present in the area of a cell layer.

The at least one stack arrangement can comprise sub-stacks that are formed from at least two segments that are either electrically connected in series at the level of the at least one stack arrangement or are electrically connected as a series connection of all segments per cell. By spatially offsetting or alternating positioning of the sub-cells or the sub-stacks in the at least two different media areas, the sub-cells or the sub-stacks share the required media connections.

The media supply is spatially separated from the connection field of the stack arrangement with negative pole and positive pole.

Furthermore, the invention relates to the use of the stack arrangement in electrochemical systems for producing hydrogen in an electrolysis device or a fuel cell for converting hydrogen into electrical current. A further use of the stack arrangement proposed according to the invention is in converting gaseous and/or liquid media into electrical current. A further use of the stack arrangement proposed according to the invention is in its use in redox flow systems for temporarily storing electrical current, in particular wet cells of vanadium redox flow batteries, zinc-bromine accumulators, polysulfite-bromite accumulators, NICD accumulators and lignin batteries.

Advantages of the invention

The stack arrangement proposed according to the invention makes it possible to multiply the stack arrangement voltage, i.e. the voltage that can be delivered by the stack arrangement. Within the at least one stack arrangement proposed according to the invention, a division into several, preferably an x · y number of sub-stacks takes place, the design of which can be one-dimensional or multi-dimensional. The individual sub-stacks or sub-cells are in turn connected in series with one another, so that the voltage level delivered by the stack arrangement proposed according to the invention is increased by a factor of x · y.

Due to the alternating sequence of sub-cells or sub-stacks, different media are required for adjacent sub-cells or sub-stacks. The design of the individual media areas and the sealing of the media areas against each other within a level can be optimized and their number reduced.

The stack arrangement proposed according to the invention can be used to achieve an electrical series connection of several sub-cells within a cell layer of the stack arrangement and several sub-stack arrangements (substacks) within a stack arrangement. The solution proposed according to the invention can achieve a significant increase in the stack voltage that can be achieved with a conventional stack arrangement beyond the usually achievable 600 volts, while maintaining a maximum number of cells per stack arrangement. In general, the maximum number of cells per stack arrangement is determined by the tolerances during stacking and their area to height ratio. The solution proposed according to the invention can be used to change the ratio of current to voltage per stack arrangement in favor of a higher voltage, which is usually more favorable for the connection to the electrical system and in particular to the power electronics. This achieves an improved connection of the at least one stack arrangement to the power electronics, including more favorable cabling (because the cross-section is reduced). A higher voltage at the stack level enables higher availability in an electrolysis system, for example when several of these stacks are connected in parallel in a larger overall system using (automatic) isolating devices for each stack, by making it possible to isolate individual stacks. This can be the case, for example, due to a defect that has occurred and/or during maintenance and repair work. In this case, there is no longer any need to shut down the entire system. This only reduces the total current within the system, which can usually be controlled very dynamically by the power electronics, particularly in the case of PEM electrolyzers.

The solution proposed according to the invention can contribute to improving process chain efficiency by enabling a higher voltage level, with a possible direct connection to medium-voltage direct current systems that operate at a voltage level of, for example, 10 kV. In such a process chain, the lossy conversion of direct current into alternating current and, after transport, from alternating current back into direct current can be reduced, optimized by simplified DC/DC conversion, or dispensed with entirely. This is particularly advantageous for renewable energy sources that generate direct current, such as photovoltaics, and for the production of green hydrogen from renewable energies.

Compared to a series connection of several stack arrangements (stacks), the invention offers the decisive advantage that the end plates, media connections and thinner connection cross-sections of the power supply only need to be provided once. At the cell level, a better ratio of the active area to the total area and a reduction in the required sealing area can also be achieved. This applies in comparison to the series connection of several stack arrangements, in which each stack arrangement requires the media channels that usually run laterally and corresponding sealing elements. The system voltage thus increases while the number of components (number of cells or sub-stack arrangements connected electrically in series) remains the same.

A higher voltage at stack level enables higher availability in an electrolysis facility when several of these stack arrangements are connected in parallel in a large overall system using (automatic) isolating devices for each stack arrangement due to the possibility of isolating individual stacks. This may be necessary due to a defect and/or during maintenance and repair work without the need to shut down the entire system. The elimination only reduces the total current within the system, which can usually be controlled highly dynamically by the power electronics, particularly in the example of PEM electrolyzers.

By designing the stacking of a stack arrangement according to the invention in such a way that it is very similar to the process of a prior art stack, it is possible to achieve a higher voltage at similar manufacturing costs. It is also conceivable that the area of the stack arrangement proposed according to the invention is larger than in the prior art, while the number of work steps remains the same. This makes it possible to reduce costs. In the case of prior art stack arrangements, however, an increase in the stack area leads to an increase in current with a proportional increase in power, i.e. the current to voltage ratio deteriorates, which has a negative effect on power losses.

Short description of the drawings

Embodiments of the invention are explained in more detail with reference to the drawings and the following description.

• 1 den Aufbau einer Stapelanordnung einer Elektrolyseeinrichtung mit ihren wesentlichen Komponenten in Seitenansicht,
• 2 eine Draufsicht auf die mindestens eine Stapelanordnung einer Elektrolyseeinrichtung gemäß 1,
• 3 eine Segmentierung eines elektrochemisch aktiven Teils in beispielsweise sechs Segmente mit versetzter Verschaltung,
• 4 umgekehrt gestapelte Zellenabschnitte mit Darstellung der Dichtung für zwei verschiedene Medienbereiche auf einer Zellebene,
• 5, 6, 7 Ausführungsvarianten von Unterstapelanordnungen,
• 8 eine weitere Ausführungsvariante einer Zellanordnung auf Zellebene mit sieben Segmenten und einem zentralen Medienkanal,
• 9 einen Querschnitt durch die Zellanordnung gemäß 8,
• 10 eine Stapelanordnung, bei der eine Anzahl von Unterstapelanordnungen in umgekehrter Orientierung zueinander in einer Stapelanordnung aufgenommen ist, mit einer getrennten Medienversorgung sowie in elektrischer Verschaltung,

They show:

• 1 the structure of a stack arrangement of an electrolysis device with its essential components in side view,
• 2 a plan view of the at least one stack arrangement of an electrolysis device according to 1 ,
• 3 a segmentation of an electrochemically active part into, for example, six segments with staggered wiring,
• 4 inverted stacked cell sections showing the seal for two different media areas on one cell level,
• 5 , 6 , 7 Design variants of sub-stack arrangements,
• 8 another variant of a cell arrangement at cell level with seven segments and a central media channel,
• 9 a cross section through the cell arrangement according to 8 ,
• 10 a stacking arrangement in which a number of sub-stack arrangements are accommodated in a stacking arrangement in reverse orientation to each other, with a separate media supply and in electrical interconnection,

1 shows a stack arrangement 12 of an electrolysis device 10. In the 1 A large number of individual cells 14 are arranged one above the other in the schematically illustrated stack arrangement 12. The individual cells 14 each comprise a membrane 16 which comprises an electrochemically active surface 18 where the electrochemical reaction takes place. On both sides of the membrane 16 there is a cathode functional surface 20 and an anode functional surface 22. The surface coated with electrodes on both sides takes part in the electrochemical reaction as an electrochemically active surface 18. For the electrochemical conversion of H ₂ O to H ₂ and O ₂ , a media supply 36, in particular an H ₂ O media supply, is required on the one hand, and a power connection and a media discharge are also required. In the area in which this is fulfilled, the chemical reaction itself takes place, in particular on the electrochemically active surface 18. The membrane 16 is therefore a CCM membrane (catalyst coated membrane). From the illustration according to 1 , which only shows a section of the stack arrangement 12, it can be seen that the individual cells 14 are each separated from one another by bipolar plates 24. The bipolar plates 24 can either be individual components or a bipolar plate 24 can be composed of a pair of monopolar plates 48, which may be (partially) electrically insulated from one another by a passivation layer, depending on the design variant.

The 1 The schematically shown stack arrangement 12 comprises an upper end plate 26 and a second, lower end plate 28. The end plates 26, 28 can also be designed as monopolar plates 48.

The individual membranes 16 with cathode functional surface 20 and anode functional surface 22 can further be equipped with at least one gas diffusion layer 50 and/or a porous stabilization layer 88, as in 1 Their respective design, in particular the porosity, can be different. The stack arrangement 12 according to 1 is designed in a stack height of 30. According to the stack height of 30, a number of individual cells 14 are stacked on top of each other. A voltage of between 1.5 volts and 2.3 volts is required per cell 14. The voltage that the 1 The required stacking arrangement 12 depends on the number of individual cells 14 stacked on top of one another in accordance with the stacking height 30. The stacking height 30 can result from a specification of the height or from a limitation of the number of cells 14 as well as from mechanical or process-related limitations.

Seals or frames 32 are located on both sides of the membrane 16. The sealing and frame functions are often realized by one and the same component.

From the top view according to 2 It can be seen that a sealing line 38 runs on the anode side, while a second sealing line 40 is provided on the cathode side. Both sealing lines 38, 40 surround the electrochemically active surface 18, which is undivided here. In the plan view according to 2 Within the stack arrangement 12 or the cell 14 shown in the top view, media connections 36 with an H ₂ O supply line 42 are provided at the anode inlet, while an (H ₂ O, O ₂ ) outlet 44 is provided at the anode outlet. The (H ₂ ) outlet (possibly with H ₂ O) at the cathode outlet is designated with reference number 46. In the case of a fuel cell, the media directions are reversed accordingly.

The 1 and 2 The stack arrangement 12 shown therefore has a seal 32 or a frame enclosed, undivided electrochemically active surface 18.

Embodiments of the invention

In the following description of the embodiments of the invention, identical or similar elements are designated by identical reference numerals, whereby a repeated description of these elements is omitted in individual cases. The figures only represent the subject matter of the invention schematically.

In order to enable a good installation within the at least one stack arrangement 12 and at the same time to ensure the correct media supply 36, as in 3 For example, the electrochemically active surface 18 of each individual cell 14 is divided in such a way that according to 3 For example, six segments (62, 64, 66, ..) can be formed. In the top view according to 3 It is shown that the electrochemically active surface 18 of the cell 14 has six segments (62, 64, 66, ..), whereby three segments lying one above the other are enclosed by the sealing line 40 (cathode) and three more of the segments are enclosed by the sealing line 38 (anode). For example, monopolar plates 48 serving as busbars at cell level 110 are shown in the plan view according to 3 the segments 62, 64, 66 are connected to one another, wherein the second segment 64 is laterally offset from the first segment 62 and the third segment 66. 3 shows further that the three segments 62, 64, 66, including the offset second segment 64, are each electrically connected in series via busbars 110 designed as monopolar plates 48. The media supply 36 here comprises the H ₂ O supply line 42, the H ₂ O, O ₂ outlet 44 and an H ₂ outlet 46. 4 shows inverted stacked cell sections with seals for two different media areas on one cell level.

4 it can be seen that the cell 14 has sealing structures which separate the individual gas spaces within the cell 14 from each other. In reverse order 105, in the illustration according to 4 For example, cathode functional surfaces 20 and anode functional surfaces 22 are arranged on the membrane 16. The cell 14 as shown in 4 can be limited by the schematically indicated lower end plate 28 including galvanic isolation 60 and on the upper side either by a bipolar plate 24 or a monopolar plate 48. The sealing structures as shown in 4 coincide with the galvanic isolation 60, negative and positive poles are also identified here in reverse order 105 by the reference numerals 70 and 72.

5 , 6 and 7 show design variants of sub-cell arrangements, each with, for example, two by three segments with alternating arrangement of adjacent segments or sub-cells, each of which is designed in different segmentation schemes or series connection concepts.

5 shows an arrangement of segments, here numbers 1, 2 and 3 as well as A, B and C, which are arranged in two different media areas. From 6 It is clear that segments 1, 2 and 3 as well as A, B and C can each be combined to form sub-stack arrangements within a stack arrangement 12. The illustrated segmentation schemes of three segments each can therefore be combined to form two sub-stack arrangements, with two segments or sub-cells being arranged in one media area and the third segment in the other media area (reverse sequence 105). It is possible to implement a series connection as a sub-stack of three segments for the stack arrangement 12 and/or to implement the electrical series connection of segments 1, 2 and 3 as well as A, B and C at cell level 111. The 6 and 7 show different designs for the arrangement or the reverse sequence 105 of the alternating arrangement of the six segments in the two media areas, which enable different designs of the electrical connection. 6 and 7 It can be seen that in these segmentation schemes, segments 1 to 6 are each connected to busbars 110 and, furthermore, the upper and lower cell levels 126, 128 are connected in series with a busbar 110. In 7 opposing cells 14 are connected to each other by the busbars 110, while in the segmentation scheme according to 7 In the uppermost cell level 126 and the lowermost cell level 128 there is a cross-connection of segments 4 and 5 and 2 and 3.

By displaying two cell levels 126, 128 (cf. 9 ) also shows the different electrical connections between the first cell level 126 and the second cell level 128 as examples, which can always be the same for adjacent cell levels (cf. 6 ) or alternate between neighboring cell levels (cf. 7 ). In the 5 , 6 , and 7 Understack busbars are designated with reference number 80.

8 shows a possible segmentation scheme for a cell arrangement 112 in the cell plane 111. According to this segmentation scheme, the cell arrangement 112 comprises seven subcells 92, 94, 96, 98, 100, 102, 104, all of which have a substantially triangular contour 114. Accordingly, the outer contour 116 of the cell arrangement 112 corresponds to 8 essentially an approximate circular shape. Position 42 designates H ₂ O media channels as supply lines, the media/(O ₂ ) discharge lines are designated with reference numeral 118. The channels are ideally designed to be functionally interchangeable. On their outer sides, the sub-cells 92, 94, 96, 98, 100, 102, 104, which are designed in a triangular contour 114, each comprise said H ₂ O media channels 118, while reference numeral 120 designates H ₂ discharge lines.

An electrical contact of the individual sub-cells 92 to 104 according to the cell arrangement 112 in the illustration in 8 takes place on their upper side 122 and on their lower side 124. For example, the connection to the underlying cell level and/or a lower end plate 28 can be made via the lower side 124 of the sub-cell 92. The electrical contact to the cell level above and/or upper end plate 26 can be made via the upper side 122. In the case of cell levels, these are each rotated by one segment to form stacks (approx. 51.4°), which creates a spiral-shaped current flow within the stack arrangement 12 when an odd number of sub-cells, in this case seven, are used. The remaining sub-cells of the cell level(s) are each electrically insulated from the level(s) above or below.

According to the illustration 9 is a lateral surface sectional view of the cell arrangement 112 according to the illustrations in 8 in a schematic manner. The section shown shows a first cell level 126 and a second cell level 128 arranged underneath. The 9 The cell level 126 shown here is limited to three subcells, namely the first subcell 92, the second subcell 94 and the third subcell 96, as well as for the second cell level 128, the seventh subcell 104, the first subcell 92 and the second subcell 94. In the representation according to 9 the two cell levels 126, 128 with the seven sub-cells 92, 94, 96, 98, 100, 102, 104 are rotated by 360°/7 against each other, so that a spiral-shaped current flow of the current in the stack arrangement 12 is possible without having to install additional busbars within the stack arrangement 12. This explains the odd number of sub-cells 92, 94, 96, 98, 100, 102, 104 within the cell level 111, as shown in 9 Only contact areas 132 between the 9 superimposed cell levels 126, 128 are required.

For reasons of clarity, feeds between cell levels and media channels that run within the seal or the frame structure 32 are shown in the lateral surface section according to 9 not shown. Only an H ₂ outlet 46 in the form of a bore is indicated. From the illustration according to 9 It follows that, by reference to 8 a voltage in the cell levels 126, 128 is thus multiplied sevenfold, thus being 14 volts instead of 2 volts, which simultaneously represents a differential voltage for the two cell levels 126, 128, which is to be provided by the insulation. Insulation could be limited to an upper and a lower mono- and/or bipolar plate 48/24, see the symmetrical division according to 8 . Every second of the sub-cells 92, 94, 96, 98, 100, 102, 104 is constructed upside down. The membrane 16, the mono- and/or bipolar plate 48, optionally with the insulator 130 and in this case two frames 32 continue to cover a complete cell level 126, 128 as one component each. Only the porous transport layer 88 (porous transport layer in the case of electrolyzers) or the media transport layers 50 (gas diffusion layer in the case of electrolyzers) are arranged in alternating order.

10 shows a stack arrangement in which a number of sub-stack arrangements are accommodated in a stack arrangement in reverse orientation to each other, with a separate media supply and electrical interconnection.

10 It can be seen that in this embodiment of the stack arrangement 12 media connections 36 in the form of a pipe system are decoupled from an electrical contact 82. The media connections 36 comprise the H ₂ O supply line 42, the H ₂ O, O ₂ outlet 44 and the H ₂ outlet 46. 10 It can be seen that in this embodiment of the at least one stack arrangement 12, several sub-stack arrangements 74, 76, 78, .. are arranged in a reverse sequence 105 with respect to the plus and minus poles 70, 72. A reverse sequence 105 of the sub-stack arrangements 74, 76, 78, .., as shown in 10 is shown, is intended that, with respect to the segments 62, 64, 66, 68, negative poles 70 and positive poles 72 are present in alternating sequence next to one another on the upper end plate 26, designed as a monopolar plate 48. The same applies analogously to the second, lower end plate 28, which can also be represented by a monopolar plate 48. Each of the sub-stacks 74, 76, 78, .. is made up of a number of cells 14 stacked one above the other. By the reverse sequence 105 of, for example, an even number of sub-stack arrangements 74, 76, 78, .. and their electrical connection in series via correspondingly segmented end plates 26, 28, a multiplication of the stack arrangement voltage can be achieved. The exemplary design variant shown in accordance with 3 It can be seen that the media connections 36, which are mostly located at the bottom, can be mechanically separated from the electrical contacts 82 located at the top (cf. position of the positive poles 72 and the negative poles 70).

The invention is not limited to the embodiments described here and the aspects highlighted therein. Rather, a large number of modifications are possible within the scope specified by the claims, which are within the scope of expert action.

Claims (23)

Stack arrangement (12) for electrochemical energy conversion with a number of cells (14) stacked one above the other, wherein the cells (14) each have a membrane (16) to which a cathode functional surface (20) and an anode functional surface (22) are assigned, and polar plates (49) as bipolar plates (24) and/or monopolar plates (48) or multipolar plates are arranged between the cells (14), wherein an electrochemically active surface (18) of the cells (14) is divided into several galvanically separated segments (62, 64, 66, 68), characterized in that within the stack arrangement (12) either sub-stack arrangements (74, 76, 78) with a number of cells (14) are electrically connected in series or cells (14) are arranged in the reverse sequence (105) with respect to one another and are electrically connected in series. Stacking arrangement (12) according to Claim 1 , characterized in that the sub-stack arrangements (74, 76, 78) are electrically connected in series with one another and/or sub-cells (92, 94, 96) at the cell level (111). Stacking arrangement (12) according to the Claims 1 and 2 , characterized in that the sub-stack arrangements (74, 76, 78) are electrically connected in series via segmented polar plates (49) as upper end plate (26) and/or lower end plate (28). Stacking arrangement (12) according to the Claims 1 until 3 , characterized in that the subcells (92, 94, 96) are electrically contacted via segmented polar plates (49) and/or are electrically connected in series. Cell (14) for electrochemical energy conversion with an electrochemically active surface (18), characterized in that the electrochemically active surface (18) is divided into several galvanically separated segments (62, 64, 66, 68). Stacking arrangement (12) according to the Claims 1 until 4 , characterized in that the electrochemically active surface (18) of the cell (14) is divided into several arbitrarily shaped segments (62, 64, 66, 68) in a one-dimensional division into one to four segments or in a multi-dimensional division into at least two segments. Stacking arrangement (12) according to Claim 6 , characterized in that the segments (62, 64, 66, 68) have the same electrochemically active area (18) or approximately the same electrochemically active area (18). Stacking arrangement (12) according to the Claims 1 until 4 , characterized in that a galvanic separation (60) of the segments (62, 64, 66, 68) is carried out by a galvanic subdivision between adjacent cathode functional surfaces (20) and/or anode functional surfaces (22) as well as gas diffusion layers (50) or porous transport layers (51). Stacking arrangement (12) according to Claim 8 , characterized in that the galvanic subdivision at the level of the anode functional surface (22) and/or the cathode functional surface (20) is carried out by an interruption of the coating and/or a passivation. Stacking arrangement (12) according to Claim 8 , characterized in that the galvanic subdivision at the level of the media transport layers, in particular the gas diffusion layer (50) and the porous transport layer (51) is carried out by an electrically insulating intermediate layer or a porous stabilization layer (88). Stacking arrangement (12) according to Claim 10 , characterized in that the porous stabilization layer (88) stabilizes the membrane (16) of the cells (14). Stacking arrangement (12) according to Claim 10 , characterized in that the porous stabilization layer (88) comprises passivated carbon foam or is formed as at least one plastic component with an integrated flow field. Stacking arrangement (12) according to the Claims 1 until 4 , characterized in that the galvanic isolation (60) on the polar plate (49), in particular a monopolar plate (48) and/or bipolar plate (24), is carried out by an IMS (Isolated Metal Substrate) process and/or a local passivation of the material of the polar plate (49). Stacking arrangement (12) according to the Claims 1 until 4 , characterized in that in different media areas are present in a cell (14). Stacking arrangement (12) according to one of the Claims 1 until 4 , characterized in that in the at least one stack arrangement (12) at least two sub-stack arrangements (74, 76) with at least two segments (62, 64, 66, 68) are formed, which are either electrically connected in series at the level of the at least one stack arrangement (12) or are electrically connected in series as a series connection of all segments (62, 64, 66, 68) per cell (14). Stacking arrangement (12) according to the Claims 1 until 4 , characterized in that by a spatial offset or an alternating positioning of the subcells (92, 94, 96, 98) or the substacks (74, 76, 78) in the at least two different media areas, the subcells (92, 94, 96, 98) or substacks (74, 76, 78) share the required media connections (36, 42, 44, 46). Stacking arrangement (12) according to the Claims 1 until 4 , characterized in that a media supply (36) is arranged spatially separable from the connection field of the stack arrangement (12) into negative pole (70) and positive pole (72). Stacking arrangement (12) according to Claim 16 , characterized in that the media supply (36) comprises an H ₂ O supply/supply line (42), an H ₂ O and O ₂ outlet (44) and an H ₂ outlet (46). Stacking arrangement (12) according to Claim 16 , characterized in that the media supply (36) is returned outside the stack arrangement (12) in the case of several connections on the stack arrangement (12). Stacking arrangement (12) according to the Claims 1 until 4 , characterized in that insulation distances for the media connections (36, 42, 44, 46) are represented by a further distant junction. Use of the stacking arrangement (12) according to one of the Claims 1 until 20 in electrochemical systems for converting gaseous or liquid media into electrical current. Use of the stacking arrangement (12) according to one of the Claims 1 until 20 to produce H ₂ in an electrolysis device or a fuel cell to convert hydrogen into electrical current. Use of the stacking arrangement (12) according to one of the Claims 1 until 20 in redox flow systems, especially wet cells of vanadium redox flow batteries, zinc-bromine batteries, polysulfite-bromite batteries, NICD batteries and lignin batteries.

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