DE102022105113A1 - Redox flow battery - Google Patents

Abstract

A redox flow battery (1) comprises a number of redox flow cells (2) which are arranged in a stack in parallel planes, with a channel system for supplying and discharging the redox flow cells ( 2) is provided with electrolyte solutions. The channel system comprises at least one longitudinal channel divider (5, 15), in particular in the form of a tube insert, which divides several partial electrolyte streams, which flow at least partially parallel to one another, onto the individual redox flow cells (2) and has an elongated, in particular cylindrical basic shape with a main direction of extension normal to the planes in which the redox flow cells (2) lie.

Description

The invention relates to a redox flow battery comprising a number of redox flow cells arranged in a stack.

Redox flow batteries are batteries made up of electrochemical cells that are supplied with electrolyte solutions flowing through them. The electrolyte solutions are typically provided in tanks. Compared to accumulators, redox flow batteries have the advantage that the capacity is decoupled from the performance. A special feature of redox flow batteries is that the electrolyte solution flows through a number of cells that are operated at different electrical potentials. This can result in undesired shunt currents. Various approaches for reducing such shunt currents are described in the prior art.

In the case of one in the JP 2019-192466 A In the redox flow battery described, shunt currents are to be reduced by providing separate tanks for the supply of individual modules of the redox flow battery. A separate pump for delivering electrolyte solution is assigned to each module.

The U.S. 9,653,746 B2 , which also deals with the topic of shunt currents, proposes specially shaped flow channels for inflowing and outflowing electrolytes on the anode side or cathode side of an electrode plate of a redox flow battery to reduce them.

The WO 2007/131250 A1 discloses an electrochemical flow module with means for suppressing shunt electrical current. This device comprises a device through which a flow can take place, in which there is a layer of an electrically non-conductive liquid with a different density than an electrolyte liquid. In this way, the electrical resistance in the electrolyte liquid circuit is to be increased. The through-flow device can be designed in particular as a U-shaped tube similar to a siphon.

one in the JP 61-269866 A described redox flow battery comprises a plurality of pipelines, with an impeller arranged in a pipeline, which is made of an electrically insulating material, is intended to contribute to the reduction of unwanted electrical currents.

The JP 2003 100337 A describes a redox flow cell through which the medium flows intermittently. Suitable distribution channels are provided for the supply and removal of electrolyte solution.

The DE 35 32 696 C1 describes a possibility of pumping electrolyte together from a common reservoir into battery cells that are not electrically connected to one another. In this case, the electrolyte is fed into the individual cells in portions, with a non-conductive barrier being implemented between the electrolyte portions. The shut-off takes the form of a stratification of electrolyte and a non-conductive liquid in supply and return lines, respectively.

The invention is based on the object of specifying options for reducing shunt currents in redox flow batteries which are more advanced than the prior art and which can be implemented easily in terms of production and process engineering.

According to the invention, this object is achieved by a redox flow battery having the features of claim 1. The redox flow battery, in a basic concept known per se, comprises a number of redox flow cells which are stacked in parallel planes, are arranged, with a channel system for the supply and disposal of the redox flow cells with electrolyte solutions being provided.

The channel system of the redox flow battery according to the application comprises at least one channel longitudinal divider, which divides several partial electrolyte streams flowing at least partially parallel to one another into individual or groups of redox flow cells and an elongated, cylindrical or prismatic basic shape with a main direction of extension normal to the planes , in which the redox flow cells forming a cell stack, i.e. stack, are located.

In various possible configurations, the longitudinal channel divider is designed to divide an electrolyte stream into at least two and at most twelve partial electrolyte streams that flow at least partially parallel to one another.

According to a first possible group of configurations, the longitudinal channel divider is a channel insert which is inserted into an arrangement of a plurality of cell frames of the redox flow cells.

In particular, the redox flow battery includes a plurality of such channel inserts. With the aid of the at least one channel insert, electrolyte solution can be fed to or from the individual redox flow cells in a streamlined manner be dissipated, with the parallel connection of partial currents within the channel insert at the same time maximizing the length of electrical paths, which contributes significantly to a reduction of shunt currents. In general, the electrical main pipe resistance, which is given between the branches in the individual cells of the redox flow battery, is significantly increased compared to conventional solutions with the help of the channel insert, without accepting significant disadvantages in terms of production costs, installation space and hydraulic function to have to. All in all, almost the entire hydraulic cross-section of an undivided channel is retained with the channel insert.

For example, the channel insert has a multi-start screw geometry, in particular in the form of a four-, six-, eight- or twelve-start thread. Individual channels are thus designed as twisted angle segments over the length of the original main channel. In this case, all angular segments supply cells or groups of cells that are offset relative to one another in the longitudinal direction of the cell stack with inlets or outlets for electrolytes.

Electrolyte solution can be transferred between the main channel, the flow cross section of which is divided into a number of parallel sub-channels, and the individual redox flow cells in various ways at defined points on the cell frames of the individual cells. The division of the electrolyte flow is possible with complex shaped or geometrically very simple channel inserts. Typically, there are openings in the cell frames with, for example, a circular or square cross section, with the main channel being formed at least in sections by such openings that are aligned with one another. The transfer openings to the individual cells located on the lateral surface of the main channel can be arranged from cell to cell in the same or different angular position around the central axis of the main channel. If, for example, the centers of all transfer openings are connected to one another by a helical line, this line can approximately describe a helical line.

Simpler variants are also possible, in which transfer openings are located, for example, only in two different positions, for example in a 90-degree position or in a 180-degree position. Here, the zero degree direction is defined, for example, as the longitudinal direction of an elongated, substantially square cell frame. In the case of the 90 degree position, the transition thus takes place in the transverse direction of the cell frame. By arranging the transfer openings in positions rotated relative to one another about the longitudinal axis of the main channel, the channel insert can be geometrically designed in a particularly simple manner. In particular, the channel insert can have straight, non-twisted walls and can thus be produced efficiently as an injection molded part or in 3D printing.

Likewise, channel inserts can be realized, by means of which several sub-channels are formed which are inclined to the longitudinal axis of the channel insert, ie to a surface normal of the planes in which the redox flow cells lie, and are parallel to one another.

In this case, too, production from plastic by means of 3D printing can be considered, with the basic shape of the channel insert not necessarily being cylindrical. If the channel insert is in the form of an elongated prism, this has advantages with regard to installation in a defined angular position.

Another alternative to helically twisted channel inserts are channel inserts that have several sections parallel to the above-mentioned surface normal of the planes in which the cells of the redox flow battery are located, i.e. running in the axial direction, as well as subsequent sections to one of the redox flow cells have open tangential sections, ie opening out at one of the transfer openings. In this case, a tangential flow means that the electrolyte flows in a plane parallel to the cell frame, with the flow direction forming a right angle with the longitudinal axis of the main channel and thus also of the channel insert.

According to a second possible group of configurations, the longitudinal channel divider is formed by stacked cell frames of the redox flow cells of the stack, with only a subset of channels separated from one another by the longitudinal channel divider being connected to each redox flow cell.

In a design that is particularly advantageous in terms of flexible production, the cell frames are designed in such a way that they can be mounted in the redox flow cell stack in one of several possible orientations, in particular in orientations rotated by 180° with respect to one another different channels penetrating the cell stack are connected to the relevant redox flow cell having the cell frame.

Regardless of the exact geometry of the channel longitudinal divider or a number of inserts that have the appropriate function, i.e. function a channel insert, designs of cell frames can be advantageous in which not only four openings are present, which can be used for anolyte inflow, anolyte outflow, catholyte inflow and catholyte outflow as required. Rather, such openings, which allow transfers from the main channel into the cells, can be present multiple times, in particular double or triple.

Of the numerous openings in the cell frame, only two are contacted on one electrode side, namely an opening for the electrolyte inlet and an opening for the electrolyte outlet, while the other openings have no hydraulic function on this electrode side. The advantage of this configuration lies in the fact that a common parts concept can be implemented that significantly reduces the manufacturing effort. This applies in particular in cases where cell frames are point- or rotationally symmetrical. The selection of the appropriate openings of each cell can be done, for example, by angling the entire channel insert or an individual insert component. The active area of the redox flow cells can be somewhat reduced due to the unnecessary, ie dead, transitions in the cell frame, which has to be accepted.

If the longitudinal channel divider according to the first group of configurations is a substantially cylindrical, bolt-shaped or tubular channel insert, according to a possible development, a cylindrical main body of the channel insert that forms the mutually parallel, optionally twisted sub-channels can have an end plate in the manner of a cap or screw head with an enlarged diameter compared to the main body. At least one groove provided for receiving a seal can be formed in this closing plate.

The channel insert of the redox flow battery is, in particular, a non-conductive component made of plastic, ceramic or impregnated fiber mats that is inert to the electrolyte. Corresponding materials or combinations of materials can also be used for the cell frames, which can also act as channel longitudinal dividers.

The walls which separate the individual sub-channels formed by the longitudinal channel divider, in particular the channel insert, have a wall thickness in the range from 0.2 mm to 4 mm, for example. The basic elasticity of the plastic ensures that the duct insert can rest against the duct wall from the inside without being damaged. Optionally, the main body of the channel insert, which is star-shaped in cross-section and in particular has four to twelve rays, is surrounded by an outer ring with holes or other openings. The material of the outer ring can be selected in particular with regard to the sealing function that it has to assume. In an analogous manner, sealing strips which form the ends of the individual wings of the multi-ray channel insert can be made of a different material than the remaining sections of the wings. Likewise, the material at the front ends of the channel insert can deviate from the material from which the middle area of the channel insert is made.

In a multi-part configuration of the channel insert, individual parts of this insert can be arranged one behind the other in its axial direction and/or parts can be nested in one another. Nesting can mean, in particular, that an inner part of the channel insert can be rotated in a tubular sleeve that is perforated at the appropriate points, which means that an adjustment option is provided. By setting the appropriate angular position of the inner part, the same type of channel inserts can be used at different points in the cell stack. It is also conceivable to connect the inner part firmly, in particular in a form-fitting manner, to the shell during the course of the production of the channel insert, with the effort in terms of tools, in particular in the case of injection molding production, being minimized by the uniform basic shapes of the inner part and shell.

The diameter of the channel insert is, for example, 20 mm to 100 mm, in particular 30 mm to 50 mm. If the channel insert has a helical shape, the pitch is only 10 mm ± 2 mm, for example. With such a small gradient, neighboring cells of the cell stack can always be connected to a different channel segment of the insert. In the case of larger thread pitches, for example a pitch in the range from 50 mm to 500 mm, there can be only a single or two revolutions over the entire length of the cell stack to be measured in the normal direction of the plate-shaped cells. In such cases, several cells are typically connected in groups to the same sub-channel. For example, eight or 20 cells are combined to form a group of redox flow cells. This also applies analogously to embodiments in which the function of channel division is taken over by the stacked cell frames.

In general, the channel longitudinal divider, in particular in the form of an elongated channel insert, i.e. pipe insert, be a one-part or multi-part component of the redox flow battery, in which case electrical shunt currents are reduced in that the hydraulic splitting of electrolyte-carrying lines into mutually parallel partial channels "detours" are created for the electrical current. Thanks to the longitudinal channel divider, these “detours” can be implemented without requiring any additional installation space worth mentioning.

• 1 eine Redox-Flow-Batterie in stark vereinfachter Darstellung,
• 2 einen Kanaleinsatz der Redox-Flow-Batterie nach 1 in perspektivischer Ansicht,
• 3 bis 5 den Kanaleinsatz nach 2 in weiteren Ansichten,
• 6 ein Detail eines abgewandelten Kanaleinsatzes für eine Redox-Flow-Batterie,
• 7 einen zweiteiligen Kanaleinsatz,
• 8 einen Kanaleinsatz mit angeformter Abschlussplatte,
• 9 den Kanaleinsatz nach 8 in einer Schnittdarstellung,
• 10 und 11 weitere Kanaleinsätze mit Abschlussplatte,
• 12 einen für die Verwendung in einer Redox-Flow-Batterie geeigneten Kanaleinsatz mit unterschiedlich geformten Teilkanälen,
• 13 in einem Diagramm Verlustleistungen in verschiedenen Redox-Flow-Batterien,
• 14 einen gegenüber den Ausführungsbeispielen nach den 2 bis 11 abgewandelten Kanaleinsatz für eine Redox-Flow-Batterie in schematisierter Darstellung,
• 15 einen weiteren Kanaleinsatz in schematisierter Darstellung,
• 16 in geschnittener Darstellung einen Kanaleinsatz mit einem zentralen Strömungskanal,
• 17 und 18 in Darstellungen analog 16 mehrteilige Kanaleinsätze für Redox-Flow-Batterien,
• 19 und 20 schematisierte Ausschnitte von Redox-Flow-Batterien mit verstellbaren Kanaleinsätzen,
• 21 bis 26 verschiedene Flussplattenanordnungen von Redox-Flow-Batterien.

Several exemplary embodiments of the invention are explained in more detail below with reference to drawings. Show in it:

• 1 a redox flow battery in a highly simplified representation,
• 2 a channel use of the redox flow battery 1 in perspective view,
• 3 until 5 the channel use 2 in further views,
• 6 a detail of a modified channel insert for a redox flow battery,
• 7 a two-part channel insert,
• 8th a channel insert with a molded end plate,
• 9 the channel use 8th in a sectional view,
• 10 and 11 additional trunking inserts with end plate,
• 12 a channel insert with differently shaped sub-channels suitable for use in a redox flow battery,
• 13 in a diagram power losses in different redox flow batteries,
• 14 one compared to the embodiments according to 2 until 11 modified channel insert for a redox flow battery in a schematic representation,
• 15 another channel insert in a schematic representation,
• 16 a sectional representation of a channel insert with a central flow channel,
• 17 and 18 analogous in representations 16 multi-part channel inserts for redox flow batteries,
• 19 and 20 Schematic sections of redox flow batteries with adjustable channel inserts,
• 21 until 26 different flow plate arrangements of redox flow batteries.

Unless otherwise stated, the following explanations relate to all exemplary embodiments. Parts that correspond to one another or have the same effect in principle are identified by the same reference symbols in all figures.

A redox flow battery marked overall with the reference numeral 1, i.e. flow battery, which is located, for example, in a motor vehicle or is part of a stationary system, comprises a plurality of redox flow cells 2, which are arranged in stack form, i.e form a stack 3. Components of the individual redox flow cells 2 include cell frames 4. The cell frames 4, like the redox flow cells 2 as a whole, are arranged in mutually parallel planes. The individual redox flow cells 2 are supplied with electrolyte solution, ie with anolyte and catholyte solution, from tanks that are not shown. With regard to the basic function of the redox flow battery 1, reference is made to the prior art cited at the outset.

In the exemplary embodiments, the electrolyte solutions with which the redox flow cells 2 are supplied flow through longitudinal channel dividers 5, 15, which can be designed either as separate components ( 1 until 12 ; 14 until 22 ) are formed or formed by the entirety of the cell frames 4 ( 23 until 26 ). In the cases of 1 until 12 as well as the 14 until 20 the longitudinal channel dividers 5 are made of plastic in the form of channel inserts 5 and have an elongated, bolt-like or helical basic shape that extends in the normal direction of the redox flow cells 2 . The appropriate alignment also have strip-shaped partition plates 15, which in the cases of 21 and 22 are provided as a longitudinal channel divider 15. In the various configurations, flow directions of the electrolyte solutions are partially identified in the figures by arrows and referred to as inflow direction ZR.

The longitudinal channel divider 5, 15, in particular in the form of the channel insert 5, forms a number of partial channels K1 to K8, which are connected on the one hand to one of the electrolyte tanks of the redox flow system and on the other hand to one of the redox flow cells 2. The channel insert 5 can be a one-piece ( 2 until 6 ; 8th until 12 ; 16 until 18 ) or a multi-part component ( 1 , 7 , 17 , 18 ) act. In the exemplary embodiments, the separating plate 15 is always in one piece.

Irrespective of whether the channel insert 5 consists of one or more parts, it can form a screw geometry 6, ie the shape of a thread. In these cases it is always a multi-thread, i.e. at least two-thread. The individual threads, ie sub-channels K1 to K8, are separated from one another by walls 7. In the exemplary embodiments, the walls 7 have a wall thickness in the range from 0.2 mm to 4 mm. The walls 7 are formed onto a central core 8, which has a cylindrical basic shape and is either solid ( 2 until 12 ) or hollow ( 16 until 18 ) can be designed. In the latter case, a central flow channel 9 is formed in the core 8 .

That section of the channel insert 5 in which the sub-channels K1 to K8 are formed is referred to as the main section 10 of the channel insert 5 . The functionality of the channel insert 5 is already given by the main section 10, which is also referred to as the main body. The main body 10 can be closed off by a front end plate 11 in the manner of a screw head ( 8th until 12 ; 16 until 18 ).

In the cases of 1 until 11 There is a six thread design of the helical shaped main body 10. An eight-course design is in 14 sketched. In the embodiment after 12 only 4 sub-channels K1, K2, K3, K4 are present. The partial channels K1 to K4 are in the form of axial sections 12 extending in the longitudinal direction of the main body 10, which are partially adjoined by tangential sections 13, i.e. sections in which the electrolyte solution flows essentially in the circumferential direction of the main body 10. As in all other embodiments, either a single redox flow cell 2 or a group of redox flow cells 2 is connected to each partial channel K1 to K4. The latter case applies, for example, to design 14 to. This also applies to the embodiment according to FIG 15 , in which the individual sub-channels K1 to K4 are positioned at an angle relative to the longitudinal axis of the channel insert 5.

In the embodiment after 16 is, as well as in the embodiment 2 , a division of the electrolyte flow into six partial flows. In contrast to the variant after 2 is however in the case of 16 exactly one partial channel K6 is connected to the central flow channel 9 present here. Furthermore, in 16 a ring-shaped circumferential groove 14 can be seen, which is located in the connection plate 11 and allows the insertion of a seal. In the cases of 17 and 18 such grooves 14 are present on both main bodies 10. The 17 and 18 12 illustrate different ways of feeding electrolyte solution through one of two main bodies 10 connected to one another to the other main body 10 of the same channel insert 5.

The division of the electrolyte flow into a plurality of partial flows, which are specified by the partial channels K1 to K8, ensures that the length of electrical paths in which shunt currents can form within the redox flow battery 1 is maximized. In this context, on 13 referred. Here nZ indicates the number of redox flow cells 2 in a redox flow battery 1 . Stacks 3 with up to 200 redox flow cells 2 are considered.

The curves designated as characteristic curves KL1, KL2, KL3 show the effects of different types of grouping of cells 2. In all cases, PVZ indicates the power loss per redox flow cell 2 (in %). The power loss PVZ tends to be greater, the larger the stack 3 is, with stacks 3 formed from no more than approx. 20 redox flow cells 2 only showing a slight increase in the power loss PVZ as the stack size increases .

In the case of the uppermost dashed curve, ie the characteristic curve KL1, there is no grouping of redox flow cells 2 whatsoever. This means that the electrolytes flow through all the cells 2 one after the other. How out 13 shows that the power loss PVZ in stacks 3, which are formed from more than 20 cells 2, rises sharply with increasing stack size.

The middle, in 13 The curve drawn with a solid line, ie the characteristic curve KL2, relates to a division of the stack 3 after 20 cells 2 each. This means that blocks of 20 cells 2 are supplied jointly, in particular through one of the channels K1 to K8, with electrolyte solution. The next 20 redox flow cells 2 are connected to the next partial channel K2 to K8. Blocks of 20 are hydraulically supplied to cells 2 like a single cell. In comparison to the variant without channel division, a drastic reduction in the power loss PVZ can be observed.

The bottom dot-dash curve in 13 , i.e. the characteristic curve KL3, refers to a division of the stack 3 after eight cells 2 each. In the case of a total of 200 cells, there are 25 hydraulically parallel blocks of 8 redox flow cells 2. There are only eight sub-channels K1 to K8 available, a stack with up to 64 cells 2 can be set up in this way. Compared to the division of 20, the power dissipation PVZ is like out 13 shows, reduced again, with stack sizes from about 100 Redox flow cells 2 practically no increase in power loss PVZ can be determined.

The 21 until 26 illustrate various options for connecting the sub-channels K1 to K8 to the cell frame 4. Symmetries of the cell frame 4 are particularly advantageous in terms of production technology. Active field components of the redox flow cells 2 are not shown. In some cases ( 21 , 22 ) Already mentioned separating plates 15 are provided, which assume the function of the simplest channel inserts 5 and thus channel longitudinal dividers.

In terms of flow, the separating plates 15 represent walls 7 of the channel insert 5 or a continuation of such walls in the direction of flow ZR. The walls 7 are optional, as shown in FIG 6 emerges, completed by widenings 16, which each engage in a groove 17 of a surrounding component, such as an end plate of the stack 3, and there ensure the required tightness. In a manner not shown, such extensions 16 are also optional for the partition plates 15 of the exemplary embodiments according to FIG 21 until 26 available.

The 19 and 20 illustrate a variant of the redox flow battery 1 with adjustable channel inserts 5. In this case, there is an eighth of a main channel 18, via which electrolyte solution is supplied to the individual redox flow cells 2. Only a single segment, i.e. 45° segment, of the channel insert 5 is open in this case and can therefore be connected to a meandering channel 19, which is formed in the cell frame 4 and to the active field of the relevant redox flow cell 2, i.e. to the area in which the electrochemical reactions take place. In addition to the variants outlined in the figures, the meandering channels 19 can have a wide variety of cross-sectional shapes, for example rectangular or semicircular cross-sections, as well as arrangements and shapes on the cell frame 4, for example meandering or spiral basic shapes. As an alternative to a meander shape, a straight, elongated shape of the channels 19 can also be considered.

In the first eighth of the stack 3, in relation to its longitudinal direction, i.e. the normal direction of the levels in which the redox flow cells 2 are arranged, the 19 outlined installation position of the channel insert 5 used; in the next eighth the in 20 Sketched installation position twisted by 45 degrees, and so on. The same applies to the removal of electrolyte solution from the stack 3 . The individual cell frames 4 can be designed differently, depending on which eighth of the main channel 18 electrolytic solution is to be transferred into the meander channel 19 .

Through possible point symmetries (see for example 22 ) a number of four different variants of cell frame 4 is sufficient. The halving of main channels 18 according to 21 and 22 represents a simplified variant of the channel division according to 19 and 20 represent. In the cases of 23 until 26 eight openings arranged outside of the active field can be seen, in these cases square openings, which can be used in a variety of ways to form main channels 18 . In this case, through each cell frame 4 only one selection, namely two pieces, of the openings is actually connected to a main channel 18 and at the same time via a meandering channel 19 to the active field of the relevant redox flow cell 2 . The other openings of the same cell frame 4 have no function as far as this redox flow cell 2 is concerned and are used to supply other redox flow cells 2 that are upstream or downstream in the longitudinal direction of the stack 3 with electrolyte solution. The channel longitudinal divider 5 are in the cases of 23 until 26 formed directly by the cell frame 4.

Reference List

1

Redox flow battery

2

Redox flow cell

3

stacks

4

cell frame

5

Duct longitudinal divider, duct insert

6

screw geometry

7

wall

8th

core

9

flow channel

10

main body

11

end plate

12

axial section

13

tangential section

14

Groove in the end plate

15

Duct longitudinal divider, partition plate

16

widening

17

groove

18

main channel

19

meander channel

PVZ

dissipation

K1 to K8

sub-channels

KL1 to KL3

curve

na

Number of redox flow cells

ZR

inflow direction

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• JP 2019192466 A [0003]
• US 9653746 B2 [0004]
• WO 2007131250 A1 [0005]
• JP61269866A [0006]
• JP2003100337A [0007]
• DE 3532696 C1 [0008]

Claims (10)

Redox flow battery, with a number of redox flow cells (2), which are arranged in stack form, lying in planes parallel to one another, with a channel system for supplying and disposing of the redox flow cells (2). electrolyte solutions is provided, characterized in that the channel system comprises at least one longitudinal channel divider (5, 15), which divides several partial electrolyte streams flowing at least partially parallel to one another onto the individual redox flow cells (2) and has an elongate basic shape with a main direction of extension normal to the levels in which the redox flow cells (2) are located. redox flow battery claim 1 , characterized in that the longitudinal channel divider (5, 15) is designed for dividing an electrolyte flow into at least two and at most twelve partial electrolyte flows which flow at least partially parallel to one another. redox flow battery claim 1 or 2 , characterized in that the longitudinal channel divider (5, 15) is designed as a channel insert which is inserted into an arrangement of a plurality of cell frames (4) of the redox flow cells (2). redox flow battery claim 3 , characterized in that the channel insert (5) has a multi-threaded screw geometry (6). redox flow battery claim 3 or 4 , characterized in that the channel insert (5) has a central inner flow channel (9) and at least one radially outer sub-channel (K1, ..., K8). Redox flow battery after one of claims 3 until 5 , characterized in that the channel insert (5) has a plurality of axial sections (12), which are aligned in the normal direction of the redox flow cell stack (3), and in each case an axial section (12) subsequent to at least one of the redox flow - Cells (2) has open tangential sections (13). Redox flow battery after one of claims 3 until 6 , characterized in that the channel insert (5) is made of plastic and has flow paths separating walls (7) with a wall thickness of 0.2 mm to 4 mm. Redox flow battery after one of claims 3 until 7 , characterized in that the channel insert (5, 15) has an end plate (11) which is connected to a main body (10) designed for flow guidance and has an enlarged diameter compared to the main body (10), in which at least one groove ( 14) is formed. Redox flow battery after one of Claims 1 until 9 , characterized in that the longitudinal channel divider (5, 15) is formed by stacked cell frames (4) of the redox flow cells (2), with only a subset of each other being separated by the longitudinal channel divider (5, 15). separate main channels (18) is connected to each redox flow cell (2). redox flow battery claim 9 , characterized in that the cell frames (4) are designed such that they can each be mounted in one of several possible orientations in the redox flow cell stack (3), with different main channels (18) in the different orientations to the relevant, the cell frame (4) having redox flow cell (2) are connected.

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