DE102022106048A1 - Flow frame for an electrochemical cell - Google Patents

Abstract

The invention relates to a flow frame (10) for an electrochemical cell, wherein the flow frame defines at least one electrode space (14) for receiving an electrode, comprising at least one supply channel system (16) for supplying electrolyte into the electrode space, the supply channel system having a fluid connection (20 ), which is fluidly connected to the electrode space via feed channel structures (22), and at least one return channel system (18) for returning electrolyte from the electrode space, the return channel system comprising a fluid connection (24), which is connected to the electrode space via return channel structures (26). is fluidly connected, wherein the supply channel structures and/or the return channel structures comprise a plurality of secondary channels (32) which exit at separate positions of the respective fluid connection and open into the electrode space via inflow areas (34).

Description

The invention relates to a flow frame for an electrochemical cell, in particular for a redox flow battery stack. The invention also relates to an electrochemical cell, in particular a redox flow battery cell.

Redox flow batteries are electrochemical energy storage devices with flowable, in particular liquid, storage media in which a redox-active material or a redox-active substance is dissolved in a liquid electrolyte. The electrolytes (called anolyte or catholyte depending on polarity) are provided separately, e.g. stored in separate tanks and, if necessary, fed to an electrochemical energy conversion unit (the so-called cell of the redox flow battery) for the charging or discharging process. During the charging or discharging process, the redox-active materials in the cell are oxidized or reduced in separate half-cells. Chemical energy is converted into electrical energy during the discharging process and electrical energy is converted back into chemical energy during the charging process. A particular advantage of redox flow batteries is that performance (number and size of electrochemical energy converters/cells) and capacity (electrolyte volume, size and number of tanks) can be adjusted independently of one another, allowing centralized and decentralized storage systems on a scale of a few kilowatts up to megawatts can be achieved.

A redox flow battery usually includes a large number of identical cells, which are fluidically connected in parallel and electrically in series. The cells are in particular assembled into a stack, the so-called cell stack, and pressed using a bracing system and, if necessary, braced using tie rods. The bracing system usually includes end plates, for example made of plastic and/or non-ferrous metals such as aluminum, between which the individual cells are arranged. In addition, the bracing system can have insulating plates for separating the current-carrying individual cells from the end plates, current collectors with electrical connections for discharging or supplying the charging or discharging current as well as media connections for supplying and discharging the electrolyte (anolyte/catholyte).

To electrically connect the individual cells to one another, a so-called bipolar plate, for example made of a graphite-plastic composite material, is usually arranged between two individual cells. Each individual cell is made up of two half cells that are separated by an ion-conducting membrane.

The half cells in turn each comprise a flow frame and an electrode, which is usually arranged in a frame opening of the flow frame. In this respect, the frame opening forms an electrode space for receiving an electrode and defines the actual effective space or effective area of the half cell, i.e. the active area in which the electrochemical processes take place. In addition, the known flow frames generally include an integrated feed channel system for feeding electrolyte into the electrode space and a return channel system for returning electrolyte from the electrode space. These channel systems usually include a fluid connection (primary channel), for example in the form of a through hole in the flow frame, from which an individual channel (secondary channel) extends, which ultimately opens into the electrode space via fan-shaped or comb-shaped distribution structures. Such a flow frame is, for example US 2018/0062188 A1 known.

However, in the known systems there are regularly high pressure drops across the primary and secondary channels, which can limit the efficiency of the redox flow battery stack and the entire redox flow battery system, particularly with high electrolyte volume flows. In addition, in the known systems, the distribution of the electrolyte in the effective space is often uneven, which can also have a negative effect on the performance of the battery.

The present invention is concerned with the task of improving the electrolyte management in a redox flow battery. In particular, high electrolyte volume flows should be able to be conducted efficiently and homogeneously through the effective spaces of a redox flow battery cell. Flexible scaling of the redox flow battery is also desirable.

This task is solved by a flow frame with the features of claim 1. The flow frame is designed for use in an electrochemical cell, in particular for use in a cell of a redox flow battery.

The flow frame delimits a frame opening for receiving an electrode. The frame opening therefore forms an electrode space for receiving the electrode. In particular, the electrode space defines the actual effective space of a half cell comprising such a flow frame.

The flow frame comprises at least one feed channel system formed in the flow frame for feeding electrolyte into the electrode space. The feed channel system includes a fluid connection (primary channel), through which electrolyte can be supplied to the flow frame. The fluid connection is fluidly connected to the electrode space via supply channel structures. The feed channel structures thus open into the electrode space.

The flow frame also includes at least one return channel system formed in the flow frame for returning electrolyte from the electrode space. The return channel system also includes a fluid connection (primary channel) through which electrolyte can be removed from the flow frame. The fluid connection is fluidly connected to the electrode space via return channel structures.

The fluid connections are connected to the electrode space in particular via the channel structures (supply channel structures or return channel structures) in such a way that electrolyte can be supplied to the electrode space, in particular an electrode arranged therein, and removed from it again via the channel systems. In particular, the fluid connections can be designed in the form of through holes in the flow frame.

The supply channel structures and/or the return channel structures comprise a plurality of secondary channels (fluid channels) which exit at different and separate positions of the respective fluid connection. Viewed the other way around, the secondary channels open into the respective fluid connection at different positions and separately from each other. At their other end, the secondary channels open into the electrode space or into the frame opening via inflow areas, in particular comprising distribution structures for distributing fluid. The secondary channels extend in particular from the respective fluid connection to the respective inflow area.

In the proposed flow frame, not only a single channel extends from a fluid connection, which then branches out, for example in a tree-like manner. Instead, a plurality of fluid channels (secondary channels) are provided, which extend from the fluid connection at different positions and are therefore fluidly connected in parallel. In particular, the secondary channels themselves have no branches. With such a flow frame, a total pressure drop between the fluid connection and the electrode space is reduced because a total electrolyte volume flow is divided into a plurality of secondary channels (segmented fluid guidance). This allows the peripheral energy requirements of a redox flow battery system to be reduced because, for example, lower pump pressures are required, which has a positive effect on the energy consumption of the peripheral units and the overall system efficiency. In addition, such a flow frame makes it possible to pass high electrolyte volume flows, for example to achieve high electrical current densities [>200 A/cm ² ], through a redox flow stack, without causing any significant loss of performance and/or an uneven distribution of the electrolyte in the electrode space in the individual cells in the stack. A design with a plurality of secondary channels also promotes a compact structure of the supply and return channel structures and thus a compact structure of the entire flow frame (material cost savings).

The flow frame can be manufactured, for example, using an injection molding process. Beneficial materials for the flow frame include polypropylene, polyethylene or polyamide.

The fluid connections can in particular be designed in the form of through holes in the flow frame. In this respect, the secondary channels can extend radially from the through hole at different positions. The flow frames can in particular be stacked on top of one another in a stack in such a way that the through holes of the flow frames are aligned with one another, so that an electrolyte line passing through the stack is formed. Preferably, the supply channel structures and the return channel structures are formed in the flow frame, for example in the form of local recesses on the surface of the flow frame. The channel structures and/or the through holes can already be produced when the flow frame is initially formed (for example in an injection molding process). However, it is also conceivable that the channel structures and/or the through holes are created in a frame surface of the flow frame by material-removing processes, e.g. drilling, punching or milling.

For a homogeneous fluid distribution in the electrode space, it can be advantageous if the supply channel system and the return channel system are designed such that the supply channel structures and the return channel structures open into the electrode space on opposite sides. In addition, it can be advantageous if a number of the secondary channels of the supply channel structures and a number of secondary channels of the return channel structures are the same. In particular, the supply channel structures and the return channel structures can be arranged point-symmetrically to an electrode space center.

A particularly homogeneous distribution of electrolyte in the electrode space can also be promoted by the fact that each secondary electrode nal flows into the electrode space via its own inflow area. In this respect, a number of secondary channels and inflow areas are preferably identical. The inflow areas of the secondary channels are preferably spatially separated from one another. The secondary channels therefore preferably open into the electrode space at separate positions. This allows high local shunt currents to be reduced when the electrolyte enters the electrode space.

In addition, it can be advantageous if the secondary channels are fluidically and electrically insulated from one another along their, in particular complete, course from the fluid connection to the electrode space. In particular, the secondary channels can be fluidically and electrically insulated from one another along their course from the fluid connection to the electrode space by material sections of the flow frame, in particular in the form of webs.

As part of an advantageous development, the secondary channels can in turn each have a plurality of, in particular parallel, subchannels or can be formed thereby. Such additional division into sub-channels further reduces the overall pressure drop. In addition, in such a configuration, a channel width per channel (subchannel) is smaller than the channel width of an individual channel with a comparable overall flow cross section to the sum of the subchannels of a secondary channel. This makes it possible to seal the secondary channels or sub-channels in a simple manner with soft sealing materials, in particular flat seals, since the small channel width prevents the sealing materials from sinking into the channels, for example when pressing in the stack, or at least to an acceptable level can be reduced. In this context, it can be advantageous if a channel width of the sub-channels is between 1 and 6 mm, preferably between 2 and 4 mm and/or a channel depth (or height) of the sub-channels is between 0.3 and 4 mm, preferably between 0 .5 and 2 mm.

The subchannels can fundamentally have the same flow cross section, in particular the same channel width and/or channel depth. It is also conceivable that a subset of the subchannels of a flow channel have a different flow cross section. It is also conceivable that a subchannel has a varying channel width and/or channel depth along its course within a secondary channel segment.

The sub-channels in turn preferably open into the respective fluid connection at different positions, in particular separately from one another. In other words, the sub-channels extend in particular from different positions of the fluid connection.

The subchannels can extend along the entire length of a respective secondary channel. In particular, the subchannels can be fluidically and electrically insulated from one another along their entire course from the fluid connection to the electrode space. For example, the subchannels can be separated from one another at least in sections by webs. The webs can be formed by material sections of the flow frame. The webs can serve as support surfaces for optional sealing elements such as flat gaskets.

However, in order to enable compensation of any pressure differences between the sub-channels, it may be advantageous if at least a subset of the sub-channels of at least a subset of the secondary channels are connected to one another via at least one transverse channel. This can be achieved, for example, by interrupting at least sections of webs that separate adjacent subchannels. It is also conceivable that transverse channels of different widths are provided.

As part of an advantageous development, the secondary channels can comprise a plurality of secondary channel segments, which are arranged one behind the other along the extension of the secondary channel from the fluid connection to the electrode space. In other words, a respective secondary channel can be divided along its course into several sections, which in their entirety form the secondary channel. The secondary channels can be designed in such a way that different segments are passed through along their extension from the fluid connection to the electrode space.

The secondary channel segments can in turn have the subchannels described above. In this context, it is possible for the secondary channel segments of a secondary channel to each have the same number of subchannels. However, it is also possible for the number of subchannels to vary between the secondary channel segments of a secondary channel. Preferably, a number and configuration of the subchannels is selected such that a pressure drop is as homogeneous as possible across all secondary channels.

Homogenization of the fluid flow through a secondary channel can be promoted in particular by having at least one secondary channel segment of the secondary channel has a smaller number of subchannels than a secondary channel segment lying along the extension of the secondary channel from the fluid connection to the inflow area in front of this secondary channel segment. In this respect, a number of subchannels can also decrease along the extent of the secondary channel from the fluid connection to the inflow region. In particular, at least a subset of the secondary channels can be designed such that a number of subchannels initially decreases and then increases again along the course of the secondary channel from the fluid channel to the electrode space, in particular does not increase from segment to segment.

The secondary channel segments can be designed such that at least a subset of the secondary channel segments of a secondary channel have a different orientation. In this respect, adjacent secondary channel segments can be arranged at an angle to one another, for example, run orthogonally to one another.

Homogenization of the fluid flow in the secondary channels can further be promoted in that at a connection point, in particular a deflection point, of two adjacent secondary channel segments of a secondary channel, the subchannels are fluidly connected to one another via a grid-like channel network. For example, the webs described above can be interrupted in sections between adjacent sub-channels in such a way that a grid-like channel network is formed. Such a design also enables pressure differences between the sub-channels to be equalized.

As part of an advantageous embodiment, the at least one supply channel system and/or the at least one return channel system, in particular the secondary channels, can be designed such that a pressure difference between the fluid connection and the respective inflow area of the secondary channels into the electrode space is between 0 and 10%, in particular between 0.1 and 1.0%.

In order to achieve the most homogeneous possible pressure drop across all secondary channels from their branch from the fluid connection to the entry into the electrode space, it can also be advantageous if the at least one supply channel system and / or the at least one return channel system, in particular the secondary channels, in particular one Configuration of the subchannels are designed such that a difference between the partial volume flows through the secondary channels is less than 10%, preferably less than 1%, in particular between 0.1 and 0.8%.

For a homogeneous distribution of electrolyte liquid in the electrode space, it can also be advantageous if segmented fluid guidance also takes place at the level of the primary channels, i.e. at the level of the fluid connections. For this purpose, as part of an advantageous development, the flow frame can have a plurality of feed channel systems described above and a plurality of return channel systems described above. In this respect, the flow frame can include several fluid connections for supplying electrolyte into the flow frame and several fluid connections for returning electrolyte from the flow frame. It is, for example, conceivable that the flow frame comprises at least two fluid connections, which are connected to the electrode space with the feed channel structures described above, and at least two fluid connections, which are connected to the electrode space with the return channel structures described above. Such a segmented fluid supply and fluid return further reduces the pressure drop, so that even high electrolyte volume flows can be conducted efficiently through the electrode space.

Advantageously, the flow frame can comprise a plurality of flow frame segments, each of which has a supply channel system and a return channel system. The flow frame segments can in particular be arranged next to one another along a frame axis. In particular, the flow frame segments each define an electrode space segment, with the electrode space segments forming the electrode space as a whole.

The flow frame segments can be designed in such a way that the electrode space segments of the flow frame segments as a whole form a continuous electrode space. For example, it is conceivable that the electrode space segments are open on one or both sides when viewed along the frame axis, so that the size of the electrode space can be variably changed by assembling several flow frame segments. If the flow frame is used as intended, a single electrode can then be provided, for example, which fills the electrode space, in particular completely.

It is also conceivable that the electrode space segments are fluidically separated from one another. In this respect, the flow frame segments can be designed in such a way that they limit a respective electrode space segment to the outside. For example, the flow frame may include a plurality of separate frame openings, each frame opening forming an electrode space segment. Each electrode space segment then has, in particular, a supply channel system and a return channel Channel system assigned in order to be able to supply electrolyte to the electrode space segment or to be able to remove it from it. If the flow frame is used as intended, an electrode can then be arranged in each electrode space segment.

The flow frame can basically be formed in one piece. In this respect, the flow frame segments can be formed by sections of the flow frame. However, it is also possible for the flow frame to be modularly composed of the flow frame segments. In particular, the flow frame segments can be formed by frame elements that are provided separately from one another and are connected to one another in a fluid-tight manner to form the flow frame. The frame elements can then in particular each enclose or at least partially delimit at least one frame opening, which forms an electrode space segment. The frame elements can, for example, be connected to one another in a materially bonded manner, for example by welding and/or gluing. It is also conceivable that the frame elements are connected in a fluid-tight manner by means of sealing elements. Such a modular design makes it possible to variably enlarge the electrode space and thus an effective effective area of a half cell in a simple manner and still achieve a low overall pressure drop.

As part of an advantageous embodiment, the flow frame segments can be designed to be identical to one another. Such a flow frame can be provided comparatively inexpensively, since economies of scale can be exploited in production due to a large number of identical parts (only one tool, mass production of identical parts).

Depending on an orientation of the flow frame segments in the flow frame, a relative arrangement of the fluid connections can then be changed. It is, for example, conceivable that the flow frame segments are arranged next to one another in the same orientation along the frame axis. Then, for example, for adjacent flow frame segments, i.e. those lying next to one another along the frame axis, a relative arrangement of the fluid connections can be identical. In this respect, the flow frame segments can in particular be designed and arranged such that a fluid connection of a flow frame segment that is fluidly connected to the electrode space is arranged next to a fluid connection of an adjacent flow frame that is fluidly separated from the electrode space. In particular, fluid connections that are fluidly connected to the electrode space and fluid connections that are fluidly separated from the electrode space segment can, in particular, alternate when viewed along the frame axis.

It is also conceivable that adjacent flow frame segments are rotated by 180° relative to one another about an axis of rotation. The axis of rotation can correspond to the frame axis. The axis of rotation can also run orthogonally to a frame plane spanned by the flow frame. The axis of rotation can also run orthogonally to the frame axis and lie in the frame plane. For example, it is conceivable that adjacent flow frame segments are arranged in such a way that a relative arrangement of the fluid connections is reversed in adjacent flow frame segments, i.e. those lying next to one another along the frame axis. In this respect, the flow frame segments can in particular be designed and arranged such that, in the case of adjacent flow frame segments, fluid connections of the same category (fluid connections fluidly connected to the electrode space or fluid connections fluidly separated from the electrode space) lie next to one another along the frame axis. This enables a particularly simple and space-saving fluid distribution to the fluid connections, since supply or return fluid connections are then preferably next to one another.

The task mentioned at the beginning is also achieved by an electrochemical cell according to claim 15. In particular, the electrochemical cell is a cell of a redox flow battery. The cell includes a first and a second half cell. The cell also includes a membrane disposed between the first and second half cells. The membrane is in particular designed to be ion-permeable at least in sections. Each half cell includes a flow frame described above and an electrode arranged in the electrode space of this flow frame. Preferably, the electrode completely fills the electrode space. The electrode can be, for example, a felt electrode, for example made of a carbon material.

As part of an advantageous embodiment, the flow frame of the first half-cell and the flow frame of the second half-cell are designed to be identical to one another, with the flow frame of the second half-cell being folded by 180° around one of its outer edges relative to the flow frame of the first half-cell.

For use in a redox flow battery, it can also be advantageous if a majority of the cells described above are stacked to form a cell stack. In order to solve the problem, a cell stack is also proposed which contains a majority of those described above Cells included. The cells are stacked on top of one another in particular along a stacking direction that is orthogonal to the frame plane spanned by the flow frame. A bipolar plate is arranged between neighboring cells. A bipolar plate is therefore assigned to two adjacent half cells.

The invention is explained in more detail below with reference to the figures.

• 1 vereinfachte schematische Darstellung einer Ausgestaltung eines Flussrahmens in einer Draufsicht und vergrößerte Ausschnitte zur Erläuterung einer beispielhaften Ausgestaltung der Kanalstrukturen;
• 2 vereinfachte schematische Darstellung zur Erläuterung einer beispielhaften Ausgestaltung eines Sekundärkanals;
• 3 vereinfachte schematische Darstellung zur Erläuterung einer Verbindung zweier Sekundärkanal-Segmente;
• 4 vereinfachte schematische Darstellung einer weiteren Ausgestaltung eines Flussrahmens;
• 5 vereinfachte schematische Darstellung einer weiteren Ausgestaltung eines Flussrahmens;
• 6 vereinfachte schematische Darstellung einer Ausgestaltung eines aus mehreren Rahmenelementen modular aufgebauten Flussrahmens; und
• 7 vereinfachte schematische Darstellung einer weiteren Ausgestaltung eines aus mehreren Rahmenelementen modular aufgebauten Flussrahmens.

Show it:

• 1 simplified schematic representation of an embodiment of a flow frame in a top view and enlarged details to explain an exemplary embodiment of the channel structures;
• 2 simplified schematic representation to explain an exemplary embodiment of a secondary channel;
• 3 simplified schematic representation to explain a connection between two secondary channel segments;
• 4 simplified schematic representation of a further embodiment of a flow frame;
• 5 simplified schematic representation of a further embodiment of a flow frame;
• 6 simplified schematic representation of an embodiment of a river frame constructed modularly from several frame elements; and
• 7 Simplified schematic representation of a further embodiment of a river frame constructed modularly from several frame elements.

In the following description and in the figures, the same reference numbers are used for identical or corresponding features.

The 1 shows a simplified schematic representation of an embodiment of a flow frame, which is designated overall by the reference number 10. The flow frame 10 is used in a cell of a redox flow battery (not shown) already mentioned above, in particular in a redox flow battery stack.

The flow frame 10 delimits a frame opening 12, in the example in the middle. The frame opening serves to accommodate an electrode (not shown) and therefore forms an electrode space 14 of the flow frame 10. The electrode space 14 forms the actual effective space of the flow frame 10, i.e. the area in in which the electrochemical processes take place.

The flow frame 10 also includes a supply channel system 16 for supplying electrolyte into the electrode space 14 and a return channel system 18 for returning electrolyte from the electrode space 14.

The feed channel system 16 comprises a fluid connection 20 for supplying electrolyte liquid into the flow frame 10. The feed channel system 16 also includes feed channel structures 22, via which the fluid connection 20 is fluidly connected to the electrode space 14 (explained in detail below). In an analogous manner, the return channel system 18 comprises a fluid connection 24 for removing electrolyte liquid from the flow frame 10 and return channel structures 26, via which the fluid connection 24 is fluidly connected to the electrode space 14.

By way of example and preferably, the fluid connection 20 of the supply channel system 16 and the fluid connection 24 of the return channel system 18 are diagonally opposite one another with respect to the electrode space 14 (cf. 1 ). Supply channel structures 22 and return channel structures 26 thus open into the electrode space 14 on opposite sides. Advantageously, the supply channel system 16 and the return channel system 18 can be arranged point-symmetrically to a center point of the electrode space 14.

In the example shown, the flow frame 10 also includes two further fluid connections 28, 30, which are not connected to the electrode space 14 via channel structures. The further fluid connections 28, 30 are, for example and preferably, also diagonally opposite one another.

By way of example and preferably, the fluid connections 20, 24, 28, 30 are designed in the form of through holes in the flow frame 10. The flow frame 10 can in particular be made of polypropylene, polyethylene, or polyamide, for example by injection molding.

In a redox flow stack (not shown), the flow frames 10 are in particular stacked on top of one another in such a way that the fluid connections 20, 24, 28, 30 of adjacent flow frames 10 are aligned with one another, so that an electrolyte line running through the stack is formed. As already mentioned, two flow frames 10 are preferably provided in a cell, which are arranged mirror-inverted. In this respect, the fluid connections 28, 30, without channel structures of a flow frame 10, can be connected to the fluid connections 20, 24 with channel structures 22, 26 of the second flow frame 10 of a cell can be fluidly connected, in particular aligned with one another.

In an exemplary application situation of the flow frame 10 in a redox flow battery, the fluid connection 20 can serve to supply one of the two electrolytes used in the redox flow battery (e.g. the catholyte) into the electrode space 14 (catholyte supply) and the fluid connection 24 can be used to return this electrolyte from the electrode space 14. The other two fluid connections 28, 30 (without channel structures) can then serve in particular to forward the other electrolyte (e.g. the anolyte) to the adjacent flow frame 10 of the cell.

How out 1 As can be seen, the supply channel structures 22 and the return channel structures 26 each comprise a plurality of, in the example shown, four, secondary channels 32, which branch off from the respective fluid connection 20, 24 at different and separate positions (see section I in 1 ). The secondary channels 32 can in this respect drain fluid from the fluid connection 20 in parallel (supply channel system) or supply the fluid connection 24 (return channel system).

The secondary channels 32 open into the electrode space 14 via separate, spatially separated inflow areas 34. The inflow areas 34 can include distribution structures for distributing electrolyte liquid into the electrode space 14.

The secondary channels 32 are fluidically and electrically insulated from one another along their entire course from the fluid connection 20, 24 to the inflow areas 34, for example and preferably by material sections 36 of the flow frame 10.

The secondary channels 32 in turn each comprise a plurality of sub-channels 38, in particular running parallel to one another (see section II in 1 ). The sub-channels 38 themselves open into the fluid connection 20, 24 at different and separate positions (see section II in 1 ). The sub-channels 38 are separated from one another at least in sections by material sections 40 of the flow frame 10 (webs 42).

Specifically, the sub-channels 38 can be formed at least in sections by local recesses in a frame surface of the flow frame 10. For example, it is conceivable that the flow frame 10 with the channel structures 22, 26 is manufactured in an injection molding process.

As in 1 , Section II, shown, the webs 42 can be interrupted in sections. The sub-channels 38 can therefore be fluidly connected to one another through transverse channels 44. In principle, it is also conceivable that the sub-channels 38 are fluidically and electrically insulated from one another along their entire course.

The 2 shows a simplified schematic representation of an exemplary course of a secondary channel 32, the sub-channels 38 being represented in simplified form by arrow lines. The secondary channel 32 includes several, for example four, secondary channel segments 46-1, 46-2, 46-3, 46-4, each of which has a plurality of subchannels 38. In the specific example, the first secondary channel segment 46-1 comprises two subchannels 38, the second secondary channel segment 46-2 three subchannels 38, the third secondary channel segment 46-3 two subchannels 38 and the fourth secondary channel segment 46-4 four subchannels 38. In this respect, the number of sub-channels 38 can vary along a course of the secondary channel 32 from the fluid connection 20, 24 to the inflow region 34. As illustrated in the transition from the second secondary channel segment 46-2 to the third secondary channel segment 46-3, the number of subchannels 38 can in particular also decrease along the course from the fluid connection 20, 24 to the electrode space 14, further in particular and then increase again.

As in 2 shown schematically, the secondary channel segments 46-1, 46-2, 46-3, 46-4 can be arranged at an angle to one another, for example run orthogonally to one another. Advantageously, at connection points 48 of two secondary channel segments 46, in particular at deflection points of two secondary channel segments 46, the subchannels 38 can be fluidically connected to one another by a grid-like channel network 50 (cf. 3 ). For example, the webs 42 can be interrupted in sections in such a way that a grid-like channel network 50 is formed.

In the example shown, the subchannels 38 each have the same channel width. However, in embodiments not shown, it is also possible for the sub-channels 38 to have different channel widths and/or channel depths. It is also possible for a channel width of a subchannel 38 to change during the transition from a secondary channel segment 46 to another secondary channel segment 46. It is also conceivable that a subchannel 38 has a varying channel width along its course within a secondary channel segment 46.

By way of example and preferably, a channel width of the subchannels 38 is between 1 and 6 mm, preferably between 2 and 4 mm and / or a channel depth (or height) of the sub-channels 38 between 0.3 and 4 mm, preferably between 0.5 and 2 mm.

As already mentioned, the segmented fluid guidance described above at the level of the secondary channels 32 can optionally also continue at the level of the primary channels (fluid connections 20, 24, 28, 30). An exemplary embodiment of such a further development with segmented fluid supply and fluid return is in 4 until 7 shown.

At the in 4 In the embodiment shown, the flow frame 10 includes, for example, two feed channel systems 16-1, 16-2 explained above and two return channel systems 18, 1, 18-2 explained above. In this respect, two separate feed channel systems 16-1, 16-2 are provided for the electrode space 14 in order to be able to supply electrolyte liquid to the electrode space 14, as well as two separate return channel systems 18, 1, 18-2 in order to be able to remove electrolyte liquid from the electrode space 14 . The corresponding supply channel structures 22-1, 22-2 and the return channel structures 26-1, 26-2 are in the 4-7 shown in simplified form as a single line, but in particular include the plurality of secondary channels 32 and subchannels 38 described above.

With those in the 4 and 5 In the embodiments shown, the flow frame 10 comprises two flow frame segments 52-1, 52-2, which run along a frame axis 54 (cf. double arrow 54 in 4 ) are arranged next to each other. Each of these flow frame segments 52-1, 52-2 includes one of the feed channel systems 16-1, 16-2 described above and one of the return channel systems 18-1, 18-2. In the example, each flow frame segment 52-1, 52-2 also includes the two already mentioned fluid connections 28-1, 28-2, 30-1, 30-2 without channel structures. As explained above, the fluid connections 28-1, 28-2, 30-1, 30-2 are preferably designed in the form of through holes in the flow frame 10 and thus form fluid passages.

The flow frame 10 can basically be formed in one piece. In this respect, the flow frame segments 52-1, 52-2 can be formed by sections of the flow frame 10. However, the flow frame segments 52-1, 52-2 can advantageously be formed by frame elements 56-1, 56-2 which are provided separately from one another and which are connected to one another in a fluid-tight manner to form the flow frame 10 (in 4 and 5 highlighted by the dash-dotted central axis 57). For example, the frame elements 56-1, 56-2 can be connected to one another in a materially bonded manner, for example by welding and/or gluing. It is also possible for the frame elements 56-1, 56-2 to be connected to one another in a fluid-tight manner via corresponding sealing elements.

How out 4 As can be seen, each flow frame segment 52-1, 52-2 or each frame element 56-1, 56-2 delimits an electrode space segment 58-1, 58-2, the electrode space segments 58-1, 58-2 forming the electrode space 14 in their entirety.

The 4 shows an exemplary embodiment in which the relative arrangement of the fluid connections 20, 24, 28, 30 is identical in both flow frame segments 52-1, 52-2. When used as intended, for example, the fluid connections 20-1, 20-2 can serve as a catholyte supply and the fluid connections 24-1, 24-2 can serve as a catholyte return. Then the fluid connections 28-1, 28-2 can serve as anolyte supply and the fluid connections 30-1, 30-2 can serve as anolyte return. It is of course also possible that the catholyte and anolyte are swapped.

The 5 shows a further embodiment in which the relative arrangement of the fluid connections 20, 24, 28, 30 is swapped in the two flow frame segments 52-1, 52-2. In such a configuration, the return fluid connections 24-1, 24-2 are arranged next to one another, which enables simple fluid removal.

By way of example, the flow framework can be according to 4 be formed by two mutually identical frame elements 56-1, 56-2, the frame element 56-2, which is the in 4 right flow frame segment 52-2 forms, compared to the frame element 56-1, which is the in 4 Left flow frame segment 52-1 forms, by 180 ° to a frame plane orthogonal to a frame plane spanned by the flow frame 10 (in 1 the axis of rotation corresponding to the drawing plane).

The 6 and 7 show further embodiments of a modular river frame 10 consisting of several frame elements 56-1, 56-2 6 In the embodiment shown, the frame elements 56-1, 56-2 each delimit an electrode space segment 58-1, 58-2 that is open on one or both sides, so that in the end a continuous electrode space 14 is formed. Such a modular structure makes it possible to add optional additional frame elements (in 6 indicated for example by the frame element 56-3' shown in dashed lines) to flexibly enlarge the electrode space 14.

At the in 7 In the embodiment shown, the frame elements 56-1, 56-2 each delimit an electrode space segment 58-1, 58-2, so that the flow frame 10 ultimately comprises a plurality of fluidically separated electrode space segments 58-1, 58-2, which in their entirety then Form electrode space 14. Also at the in 7 In the embodiment shown, the effective electrode space 14 can be enlarged overall by adding optional further frame elements 56-3' and thus further electrode space segments 58-3'.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed 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.

Cited patent literature

• US 20180062188 A1 [0005]

Claims (15)

Flow frame (10) for an electrochemical cell, in particular for a cell of a redox flow battery, wherein the flow frame (10) defines at least one electrode space (14) for receiving an electrode, comprising: - at least one feed channel system (16, 16-1 , 16-2) for supplying electrolyte into the electrode space (14), the supply channel system (16, 16-1, 16-2) comprising a fluid connection (20, 20-1, 20-2), which has supply channel structures (22 , 22-1, 22-2) is fluidly connected to the electrode space (14); - at least one return channel system (18, 18-1, 18-2) for returning electrolyte from the electrode space (14), the return channel system (18, 18-1, 18-2) having a fluid connection (24, 24-1, 24 -2), which is fluidly connected to the electrode space (14) via return channel structures (26, 26-1, 26-2); characterized in that the supply channel structures (16, 16-1, 16-2) and/or the return channel structures (18, 18-1, 18-2) comprise a plurality of secondary channels (32) which are at separate positions of the respective fluid connection ( 20, 24) and flow into the electrode space (14) via inflow areas (34). Flow frame (10). Claim 1 , each secondary channel (32) opening into the electrode space (14) via its own inflow area (34), in particular the inflow areas (34) of the secondary channels (32) being spatially separated from one another. Flow frame (10) according to one of the preceding claims, wherein the secondary channels (32) are fluidically and electrically insulated from one another along their course from the fluid connection (20, 24) to the electrode space (14). Flow frame (10) according to one of the preceding claims, wherein the secondary channels (32) each have a plurality of, in particular parallel, sub-channels (38). Flow frame (10). Claim 4 , wherein the sub-channels (38) extend at separate positions of the respective fluid connection (20, 24) and/or wherein the sub-channels (38) of a secondary channel (32) are separated from one another at least in sections along their longitudinal extent by webs (42). Flow frame (10) according to one of the Claims 4 or 5 , wherein the subchannels (38) of at least a subset of the secondary channels (32) are connected to one another via at least one transverse channel (44). Flow frame (10) according to one of the preceding claims, wherein the secondary channels (32) each comprise a plurality of secondary channel segments (46-1, 46-2, 46-3, 46-4) which run along the extent of the respective secondary channel ( 32) are arranged one behind the other from the fluid connection (20, 24) to the electrode space (14). Flow frame (10). Claim 7 , wherein at least one secondary channel segment (46-3) of at least one secondary channel (32) has a smaller number of sub-channels (38) than one along the extent of this secondary channel (32) from the fluid connection (20, 24) to the inflow region (34 ) secondary channel segment (46-2) lying in front of this secondary channel segment (46-3). Flow frame (10) according to one of the Claims 7 or 8th , wherein at least a subset of the secondary channel segments (46-1, 46-2, 46-3, 46-4) of a secondary channel (32) have a different orientation. Flow frame (10) according to one of the Claims 7 until 9 , wherein at a connection point (48), in particular a deflection point, of two secondary channel segments (46-1, 46-2, 46-3, 46-4) of a secondary channel (32), the subchannels (38) are connected via a grid-like channel network (50). are connected to each other. Flow frame (10) according to one of the preceding claims, wherein the at least one supply channel system (16) and/or the at least one return channel system (18) are designed such that a pressure difference between the fluid connection (20, 24) and the inflow area (34) of a respective secondary channel (32) is between 0 and 10%, preferably between 0.1 and 1.0%. Flow frame (10) according to one of the preceding claims, wherein the at least one supply channel system (16) and/or the at least one return channel system (18) are designed such that a difference between the partial volume flows through the individual secondary channels is less than 10%, preferably less than 1%. , in particular between 0.1 and 0.8%. Flow frame (10) according to one of the preceding claims, wherein the flow frame (10) comprises at least two flow frame segments (52-1, 52-2) which are arranged next to one another along a frame axis (54), each of these flow frame segments (52-1, 52-2) defines an electrode space segment (58-1, 58-2), the electrode space segments (58-1, 58-2) forming the electrode space (14) in their entirety, and each of these flow frame segments (52-1, 52-2) comprises a supply channel system (16) and a return channel system (18). Flow frame (10) according to one of the preceding claims, wherein the electrode space segments (58-1, 58-2) form a continuous electrode space (14) or wherein the electrode space segments (58-1, 58-2) are fluidically separated from one another. Electrochemical cell, in particular for a redox flow battery, comprising a first and a second half cell, a membrane being arranged between the first and the second half cell, each half cell having a flow frame (10) according to one of the preceding claims and one in which Electrode space (14) of this flow frame (10) comprises an electrode arranged.

Images