EP4085487A1

EP4085487A1 - Modular flow frame for an electrochemical cell, flow frame electrode unit, cell, cell stack, and method for producing a flow frame

Info

Publication number: EP4085487A1
Application number: EP21835687.1A
Authority: EP
Inventors: Andreas Schiegl; Udo Martin; Lars KÜHNLE; Christian Teufel
Original assignee: J Schmalz GmbH
Current assignee: J Schmalz GmbH
Priority date: 2020-12-18
Filing date: 2021-12-09
Publication date: 2022-11-09
Also published as: AU2021399753A1; US20240047710A1; KR20230122091A; CN116686126A; WO2022128737A1; JP2024500031A; DE102020134157A1; AU2021399753A9

Abstract

The invention relates to a modular flow frame (10) for an electrochemical cell, in particular for a cell of a redox flow battery stack, comprising a frame main part (14) which defines a frame opening (18), wherein the frame main part has a profiled cross-section, preferably a substantially U-shaped profiled cross-section, which is open on one side in the direction of the frame opening such that a profiled receiving area (26) which is open towards the frame opening is formed. The modular flow frame additionally comprises an insert (16) which is arranged in the profiled receiving area of the frame main part, wherein the insert has channel structures for distributing fluids in the frame opening. The invention additionally relates to a flow frame electrode unit, a cell, a cell stack, and a method for producing a flow frame.

Description

Title : Modular Flux Frame for an Electrochemical

Cell, flux frame electrode unit, cell, cell stack, and method for producing a flux frame

description

The invention relates to a modular flow frame for an electrochemical cell, in particular for a redox flow battery stack. The invention also relates to a flux frame electrode unit, a cell, a cell stack and a method for producing a flux frame.

Redox flow batteries are electrochemical energy stores with free-flowing, especially 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. B. stored in separate tanks and, if required, fed to an electrochemical energy converter unit (the so-called cell of the redox flow battery) for the charging or discharging process. When loading or During the discharging process, the redox-active materials in the cell are oxidized in separate half-cells or reduced . Here, chemical energy is converted into electrical energy during the discharging process and electrical energy is converted back into chemical energy during the charging process. In particular, one advantage of redox flow batteries is that the power (number and size of the electrochemical energy converters/cells) and capacity (electrolyte volume, size and number of tanks) can be adjusted independently of one another, enabling centralized and decentralized storage systems on a few kilowatt scale up to megawatts can be realized .

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 a stack, the so-called Cell stack, assembled and pressed using a bracing system and, if necessary. braced by means of tie rods. The bracing system usually includes end plates made of plastic and/or non-ferrous metals such as aluminum, between which the individual cells are arranged. In addition, the bracing system can be fitted with plastic insulating plates to separate the current-carrying individual cells from the end plates, Current collectors with electrical connections for deriving or Have supply of charging or discharging current and media connections for the supply and removal of the electrolyte (anolyte / catholyte).

To electrically connect the individual cells to one another, a so-called bipolar plate, e.g. arranged from a graphite plastic composite material. Each individual cell is made up of two half-cells, which are separated by an ion-conducting membrane. For their part, the half-cells generally comprise a flux frame and an electrode on which the redox processes take place. In a cell stack, the individual components are stacked between the end plates in the following order: bipolar plate, flux frame with electrode, membrane, flux frame with electrode, bipolar plate, flux frame with electrode, etc.

Together with the electrodes, the flux frames define the actual effective space of each half-cell, ie the active area in which the electrochemical processes take place. Here, the flux frames fulfill several functions. In particular, the flux frames serve on the one hand to fluidly seal the active space against the environment with the help of seals integrated in the flux frame surfaces (sealing function) and on the other hand to electrically insulate the half-cells of a cell from one another (isolation function). In addition, the flow frames usually include integrated flow channels for inflow and outflow Dissipation and for the distribution of the electrolyte in the effective space of the cell (fluid distribution function).

known, e.g. from US 2018/0062188 A1 are one-piece, plate-shaped flow frames which include integrated flow channels for supplying and removing electrolyte and for distributing the electrolyte over a wide area in the effective space of the cell. Also known from US 2016/0006046 A1 is a one-piece flux frame made of an elastomer material, in which distribution channel structures for the electrolyte are incorporated. The known flux frames are comparatively complex to manufacture because of their structure. Such flux frames are usually produced by machining (milling, drilling, etc.) or by means of injection molding or injection compression molding processes. While machining is comparatively time-consuming and expensive due to the high level of equipment required and long machine running times, injection molding processes involve high investment costs for tools and high technological challenges in terms of shape, evenness, dimensional accuracy, surface quality, etc. disadvantageous . Particularly in the case of injection molding processes, the size of the flux frame and the specific design of the channel structures are determined by the injection molding tool used and cannot be changed without major investment outlay.

The present invention is concerned with the task of providing a configuration for a redox flow battery that can be flexibly adapted to various requirements enable . In particular, a flow frame is to be provided which can be produced inexpensively and flexibly adapted to different requirements.

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

The flux frame has a modular structure and includes a frame base body which delimits a frame opening, preferably in the middle. In particular, the frame opening defines the actual effective space of the cell.

Viewed in the circumferential direction around the frame opening, the basic frame body has, at least in sections, a cross-sectional profile that is open on one side, namely in the direction of the frame opening, so that a profile receiving space that is open toward the frame opening is formed. The profile receiving space can, in particular, completely or partially encircle the frame opening.

The flux frame also includes an insert, which is arranged in the profile receiving space of the frame body. In this respect, the profile receiving space forms in particular a type of receiving pocket for the insert. The insert is in particular designed separately in that the insert for assembling the flux frame as a separate Element is provided and then inserted into the profile receiving space.

The insert comprises channel structures for the distribution of fluids, in particular over a wide area, in the frame opening. In particular, the insert includes channel structures for the areal distribution of electrolyte liquid in the active space. The channel structures can preferably be comb-shaped or fan-shaped, which enables a homogeneous distribution of a fluid, in particular electrolyte fluid, in the frame opening. In particular, the insert also has channel structures for supplying and/or removing the fluid. For this purpose, it can also be advantageous if the basic frame body has corresponding fluid channels for feeding the channel structures of the insert, in particular in the form of bores.

The insert serves as a spacer within the profile receiving space and for distributing the electrolyte liquid in the active space. The insert can in particular be loosely inserted into the profile receiving space, that is to say it can be joined to the basic frame body in a non-destructively detachable manner. However, it is also conceivable that the insert is firmly connected to the basic frame body, for example by welding and/or gluing. The insert can completely or partially surround the frame opening. The insert can in particular be designed in the form of a one-part or multi-part insert frame. The insert is preferably received in a form-fitting manner in the profile receiving space of the basic frame body. In addition, it can be advantageous if the insert is designed and arranged in the profile receiving space of the frame body in such a way that the insert does not protrude from the profile receiving space. In this respect, the insert can be enclosed on three sides by the basic frame body and sealed by it.

With such a modular flow frame, the sealing function and fluid distribution function are distributed to different components—frame base body and insert—and thus decoupled from one another. A high degree of flexibility can be achieved in this way. In particular, such a modular structure makes it possible to produce flux frames with individually adapted properties in a simple and at the same time inexpensive manner. For example, by using different inserts, it is possible to adjust a flow profile through the frame opening as required—for example as a function of an electrolyte used—without the basic shape of the frame body having to be changed. This makes it possible, for example, to provide a uniform type of basic frame body into which different inserts can then be inserted, depending on the requirement.

Due to the fact that the insert is formed separately from the basic frame body, the basic frame body and the insert can be made of different materials, in particular. This makes it possible for the respective functions of the frame body or depositors Choosing individually advantageous materials and combining them in a flow frame. For example, it is conceivable that the frame base body is made of a comparatively soft material in order to achieve a good sealing effect on neighboring components (e.g. on the membrane, bipolar plate or other flow frame when used in a cell stack), while the insert is made of a comparatively hard material is made to provide a sufficient mechanical dimensional stability of the channel structures, which is required for a reliable electrolyte flow.

A flux frame that is modularly constructed from the frame base body and insert can also be produced in a simple and cost-effective manner. Due to the fact that no fluid distributor structures have to be integrated in the basic frame body, the basic frame body can be produced from profile elements which are of comparatively simple design and can therefore be produced inexpensively. For this purpose, it is particularly advantageous if the cross-sectional profile of the basic frame body is designed to be extrudable, ie is designed in such a way that the cross-sectional profile can be produced by means of an extrusion process.

Preferably, the cross-sectional profile is essentially U-shaped. The cross-sectional profile then includes, in particular, two long legs and one short leg. The long legs can be of the same length or of different lengths. Within the meaning of the invention, U-shaped does not rule out that the basic frame body seen in cross section, has local recesses and/or projections on its outside.

Within the framework of a preferred embodiment, the basic frame body can comprise a plurality of extruded profile parts. This makes it possible to produce basic frame bodies of different sizes and geometries in a simple and cost-effective manner, and thus to implement redox flow cells with different active effective areas and thus different outputs. Only the insert with the electrolyte distribution structures has to be varied and adapted accordingly. The profile parts have, in particular, a cross-sectional profile that is open on one side, so that a profile part receiving space is formed in each case. The profile part receiving spaces of the profile parts then provide the profile receiving space of the basic frame body. The extruded profile parts preferably already have the desired cross-sectional profile of the basic frame body, for example a substantially U-shaped cross-sectional profile. Basically, it is also conceivable that the profile parts from several extruded profile segments of different geometry, z. B. L-profiles are assembled.

In particular, at least a subset, but preferably all profile parts of the basic frame body have the same cross-sectional profile. In this respect, the individual profile parts are preferably identical in their basic shape and differ only in their length. With such a design, it is possible in particular to produce the profile parts using the same extrusion die, e.g. by cutting a corresponding endless profile strand to length.

The basic frame body can be composed of a plurality of profile parts. The profile parts are preferably connected to one another at their ends to form the basic frame body. The profile part receiving spaces of the profile parts then together form a profile receiving space of the frame base body that completely surrounds the frame opening. For example, a basic frame body with a rectangular basic shape can be composed of two short profile parts and two long profile parts.

It is also possible for the profile parts to be connected to one another via connecting parts. In particular, the basic frame body can comprise two profile parts and two connecting parts connecting the profile parts to one another. The connecting parts are then in particular designed and arranged between the profile parts in such a way that they engage with a respective end section in the profile receiving part spaces of the profile parts, in particular in a form-fitting manner. In this respect, the connecting parts together with the profile parts form the basic frame body. In particular, the connecting parts are not completely accommodated in the profile part receiving spaces, but rather form a part of the structure directly delimiting the frame opening with a central section. The connecting parts and the Profile parts are formed separately in particular in that the profile parts and the connecting parts for assembling the flux frame are provided as separate elements and are joined together. For a secure connection, it can also be advantageous if the connection parts have connection contours, for example tap in the form of connecting, have. Then the profile elements corresponding counter-connection contours, for example. in the form of corresponding recesses, into which the connection contours engage in the assembled configuration. The connecting parts can, for example. be produced by means of extrusion processes or injection molding processes. In an embodiment with connecting parts, the insert comprises, in particular, a plurality of separate insert parts, one insert part being arranged in each profile part receiving space of the two profile parts.

The profile parts are preferably connected to one another in a fluid-tight manner. For this purpose, it can be advantageous in an embodiment of the frame body without connecting parts if the profile parts are cut to length at their ends with a miter and are connected to one another in a material-locking manner, e.g. by gluing and/or welding. In an embodiment of the basic frame body with connecting parts, the profile parts can be connected to one another in a fluid-tight manner via the connecting parts. Preferably, the connecting parts are firmly connected to the profile parts, for example by welding and/or gluing. Because the connecting parts engage in the profile receiving spaces of the profile parts, a comparatively large connecting surface is provided, which promotes reliable sealing.

The channel structures of the insert can run inside the insert. To this extent, the channel structures can be internal, ie surrounded by insert material. However, it is preferred if the channel structures of the insert are formed by recesses on the outside of the insert. In this respect, the channel structures are preferably formed on the outside on a surface of the insert. Such external channel structures are relatively easy to produce, for example. by machining the outside of the insert or by embossing. In such an embodiment, the channel structures are then open on one side. In particular, the external channel structures are then closed by an inner wall of the basic frame body when the insert is installed as intended in the basic frame body, so that closed fluid channels are formed in cooperation with the basic frame body.

In this context, it can also be advantageous if the insert has sealing contours on its outer surface for sealing against the basic frame body. Sealing contours are preferably provided for sealing the, in particular external, channel structures of the insert. For this purpose, the sealing contours in particular be arranged in such a way that they enclose a channel structure between them, in particular follow a course of the channel structure. An advantageous embodiment of the sealing contours can consist in particular in that the insert has at least one, in particular peripheral, projection on its outside. With the intended arrangement of the insert in the profile receiving space, the at least one projection of the insert can then dig into the preferably softer frame base body and in this way provide a sealing effect. Alternatively or additionally, it is also possible for the basic frame body to have corresponding counter-seal contours. For example, the basic frame body can have at least one corresponding, in particular circumferential, groove on its inner wall facing the profile receiving space, into which the at least one projection of the insert engages when the insert is arranged as intended in the profile receiving space. Of course, it is also possible for the insert to have at least one groove and for the basic frame body to have at least one projection.

In order to ensure a good sealing effect between the depositor and the frame body and between adjacent frame bodies, for example. when using the flux frame in a cell stack, it can also be advantageous if the frame base body is made of an elastomer that is chemically resistant to the electrolyte, in particular consists of it. At a If the basic frame body is configured from profile parts, it is particularly preferred if the profile parts are made of an elastomer that is chemically resistant to the electrolyte and at the same time extrudable. Preferably, the frame body or the profile parts are made of a thermoplastic elastomer, in particular thermoplastic polyethylene (TPE), thermoplastic polystyrene (TPS), thermoplastic polyurethane (TPU), a thermoplastic vulcanizate (TPV) or combinations of these materials.

It is particularly advantageous if the elastomer from which the basic frame body or the profile parts are produced, has a Shore hardness in the range from 40 to 90 Shore A, preferably in the range from 50 to 80 Shore A. Such an elastomer is soft enough to achieve a good seal between the frame body and adjacent components (e.g. inserts, bipolar plate, membrane, etc.), but still has sufficient mechanical strength, e.g. in order to provide sufficient dimensional stability when the basic frame body is later pressed in a cell stack.

In particular, the insert is made from a different material than the basic frame body. The insert is preferably made of a plastic that is harder and/or stiffer than the material of the basic frame body. The combination of softer frame base material and harder insert material can create a good seal between the two Components are achieved, for example. via the sealing contours described above. In addition, by forming the insert from a comparatively hard material, it can be ensured that a cross section of the channel structures of the insert does not or is changed only very slightly. In this way, a reliable flow of fluid can be ensured. The insert is preferably made from a thermoplastic material, in particular from polypropylene (PP), polyethylene (PE) and/or polyvinyl chloride (PVC). The depositors can easily mechanically, for example. be manufactured by milling or, in the case of larger quantities, by a cost-effective injection molding process.

The insert can be designed in one piece, in particular monolithically, for example in the form of an insert frame. This enables easy handling of the insert when assembling the flux frame.

However, the insert can also be made in several parts. In particular, the insert can comprise at least two, preferably two or four, separately formed insert parts. The inserts can then easily be placed separately in the profile receiving space of the frame body or are inserted into the profile part receiving spaces of the profile parts. A multi-part design of the insert makes it possible to easily adapt an electrolyte distribution in the active space to different requirements (e.g. depending on the electrolyte used or depending on the size and geometry of the frame body, etc. ) flexible to adapt . For example, a flow profile of the electrolyte liquid in the active space can be adjusted individually through a specific arrangement and configuration of the insert parts. In particular, it is conceivable that a set of standard insert parts is provided, which can then be flexibly combined depending on requirements. Such a modular structure from standard components is particularly cost-effective. In principle, it is conceivable, for example, for insert parts with different channel structures to be provided at different positions around the frame opening. It is also conceivable that only a subset of the insert parts has channel structures at all. The insert parts can in particular have different geometries, for example rectangular, L-shaped, or trapezoidal basic shapes. It is also possible for the insert parts to have differently shaped channel structures.

In an embodiment of the basic frame body with a rectangular basic shape, it can be particularly advantageous if, preferably only, those insert parts which are arranged on the longitudinal sides of the basic frame body have channel structures for distributing the fluid in the frame opening. The electrolyte then only has to cover a comparatively short flow path through an electrode arranged in the frame opening (namely along the short sides of the flux frame) so that the pressure drop when flowing through the electrode is small.

The insert parts are preferably connected to one another in a fluid-tight manner when arranged as intended in the frame base body. For this purpose, the insert parts can be connected to one another to form an insert frame, in particular in a material-locking and/or positive-locking manner, for example via tongue-and-groove connections.

As part of an advantageous development of the flow frame, the flow frame can have a receiving area for receiving a bipolar plate (bipolar plate receiving area) and/or have a receiving area for receiving a membrane (membrane receiving area). When using the flow frame in a cell or a cell stack, a membrane or be arranged a bipolar plate. The recording areas enable easy positioning of the bipolar plate or Membrane and at the same time promote a secure, position-accurate mounting of the membrane or bipolar plate . In particular, a bipolar plate receiving area and a membrane receiving area are formed on opposite outer sides of the flow frame.

A preferred embodiment consists in that the respective receiving area is formed by a recess on an outer side of the basic frame body. In particular, the frame body at least one those outer sides which are oriented parallel to a frame plane spanned by the frame opening have a recess bordering the frame opening and surrounding it. Preferably, the recess is stepped in cross-section viewed along the direction of rotation. In this respect, the basic frame body has in particular an edge which extends orthogonally to the plane of the frame and surrounds the frame opening and which forms a stop for the bipolar plate or the membrane. A recess forming the bipolar plate receiving area and a recess forming the membrane receiving area are arranged in particular on opposite outer sides of the frame base body.

If the basic frame body is composed of several profile parts, the profile parts can have a stepped recess, at least on one of those outer sides which are oriented orthogonally to the open side, in particular on both opposite outer sides, which extends along the entire longitudinal extension of the profile parts . Such a profile part is then designed so that it can be extruded.

To seal a arranged in the bipolar plate receiving area bipolar plate or. to seal a membrane arranged in the membrane receiving area, it can also be advantageous if the basic frame body has peripheral sealing lips for fluid-tight sealing of a bipolar plate and/or membrane lying thereon. For sealing flux frames arranged next to each other, e .g . B. when used in a cell stack, it can also be advantageous if the frame base body has a groove surrounding the frame opening on one of those outer sides which are oriented parallel to a frame plane spanned by the frame opening and on the opposite outer side a corresponding, the frame opening has a peripheral projection. In this respect, the frame body is designed in particular in such a way that flux frames arranged next to one another can be connected to one another in the manner of tongue and groove, in particular in a fluid-tight manner.

If the basic frame body is composed of several profile parts, the individual profile parts on one of those outer sides which are oriented orthogonally to the open side can extend along their longitudinal extent, in particular from their respective first end to the second end Have a groove and have a corresponding projection on their opposite outside. Such a profile part is designed to be extrudable.

To solve the problem mentioned at the outset, a flux frame-electrode unit is also proposed, which in particular comprises a flux frame described above and an electrode. The electrode is preferably arranged within the frame opening, ie in particular bordered by the flux frame. In particular, the electrode is designed and arranged in such a way that it Completely fills the frame opening. The electrode can in particular be a felt electrode, preferably made of a carbon material, for example. from a graphite felt z.

Within the scope of an advantageous embodiment, the electrode can in particular be designed and arranged in such a way that the electrode is flush with the inner edges of the frame base body facing the frame opening. In such an embodiment, the profile receiving space is closed by the electrode on its open side. Electrolyte liquid flowing through the channel structures of the insert in the direction of the frame opening can then be taken up directly by the electrode and reduced or dissolved in it. to be oxidized.

As part of an alternative advantageous embodiment, the electrode can also be designed and arranged in such a way that the electrode penetrates in sections into the profile receiving space of the frame base body. A penetration depth is preferably 1 to 5 mm. In this way, it can be ensured in particular that an electrolyte liquid flowing out of the channel structures of the insert first hits the electrode, so that any electrical potential differences between the electrolyte and the cell that may be present there can be reduced. For this purpose, it can also be advantageous if the electrode is taken in a form-fitting manner in the profile receiving space. Furthermore, a cell for a redox flow battery is proposed, which comprises a first and a second flow frame electrode unit explained above. The cell also includes a membrane, which is arranged between the first and the second flux frame electrode assembly. In particular, the flux frame electrode units each form a half cell of the cell. The membrane enables ion exchange between the half-cells. For this purpose, the membrane is designed to be ion-conducting, in particular made from an ion-conducting material. The membrane is preferably accommodated in an above-described membrane accommodation area of the flow frame.

Within the framework of an advantageous embodiment of such a cell, the two flux frames can be of identical design. The flux frame of the second flux frame-electrode unit can then be folded around one of its outer edges by 180°, in particular relative to the flux frame of the first flux frame-electrode unit. In such an embodiment, only one flux frame type is required for the construction of a cell, which enables the cell to be manufactured particularly cost-effectively.

For use in a redox flow battery, it can be particularly advantageous if a plurality of the cells described above are stacked to form a cell stack. It is therefore proposed to solve the problem, a cell stack, which a plurality of includes cells described above. In particular, the cells are stacked on top of one another along a stacking direction that is orthogonal to the stacking direction that is orthogonal to the frame plane spanned by the flux frame. A bipolar plate is in each case arranged between adjacent cells. In this respect, a bipolar plate is assigned to two adjacent half-cells. The bipolar plates are preferably arranged in the bipolar plate receiving areas described above.

In particular, a respective bipolar plate completely covers the frame opening of the adjacent flux frames. In order to ensure a good seal between the flux frame and the bipolar plate or between the flux frame and the membrane, it can be particularly advantageous if the bipolar plates and/or the membranes are designed and arranged in such a way that - viewed in the stacking direction - they are in a direction orthogonal to the stacking direction with the respective insert of the adjacent flux frame - Partially overlapping the electrode units. The bipolar plate and/or the membrane extend radially beyond the frame opening in particular in such a way that they partially cover the insert of the adjoining flux frame when viewed in the stacking direction. When the components in the cell stack are pressed, the bipolar plate or Membrane supported by the insert. In this way, a homogeneous force distribution can be achieved, which ensures good sealing between the individual components of a cell stack, in particular between the bipolar plate, frame base, insert and membrane. favored . An overlap between the bipolar plate and insert or between membrane and insert 1 to 40 mm, in particular 5 to 15 mm.

A further advantageous development of the cell stack can consist in the fact that a respective flow frame is connected in a fluid-tight manner to the other flow frame belonging to the same cell and/or to the flow frame of an adjacent cell. In particular, the flux frames can be connected to one another and sealed from one another via the tongue and groove connection described above. In principle, however, there is also the possibility that the individual flux frames on the surrounding surfaces, e.g. are joined together in a fluid-tight manner by means of welding and/or gluing. Additional sealing lips can reduce the surface forces for pressing the components of the cell stack

(Frame body, insert, membrane, bipolar plate, etc.) can be reduced to one another.

The task stated at the outset is also achieved by using a flow frame as described above in a redox flow battery, in particular in a cell of a redox flow battery. As already explained, the modular design of the flux frame makes it possible to implement redox flow batteries with different active effective areas and thus power in a simple and cost-effective manner. For the rest, reference is made to the features and advantages explained above in connection with the flux frame. In order to produce a flux frame as described above, a method is proposed in particular, which comprises the following steps. The features and advantages explained above in connection with the flux frame as such can be used to design the method.

According to the method, a plurality of profile parts is provided. For this purpose, in particular, a profile strand is extruded, which has a cross-sectional profile that is open on one side, preferably essentially U-shaped, so that a profile part receiving space that is open on one side is formed. The extruded profile is then cut to length to form the profile parts according to a desired size of the later flux frame.

Fluid channel structures can optionally be produced in at least a subset of the profile parts. For this purpose, in particular locally defined recesses can be produced in the corresponding profile parts, preferably by drilling or punching.

For further assembly, it can be advantageous if the profile parts are placed in an assembly device.

The assembly device is designed in particular in such a way that it defines a rectangular receiving space whose inner circumference essentially corresponds to an outer dimension of the future frame body. In a further process step, the profile parts are connected to the frame base body in a fluid-tight manner, in particular in a material-tight manner, at connecting sections. For this purpose, after cutting to length, connection contours can be produced at the respective ends, in particular at the front sides, of the profile parts, for example by cutting or punching out. Within the framework of an advantageous embodiment, the profile parts can first be mitred to length at the respective end faces and then connected to one another at their end faces by welding and/or gluing. The profile parts can also be connected to one another via the connecting parts described above. Then the profile parts and the connecting parts are first joined together mechanically and then connected to one another with a material fit.

According to the method, a depositor or a plurality of insert parts are provided and inserted into the profile receiving spaces of the profile parts.

According to an advantageous embodiment of the method, the depositor or the insert parts are inserted into the profile part receiving spaces of the individual profile parts before the profile parts are connected to form the basic frame body. However, it is also possible that the depositor or the inserts are inserted into the profile receiving space of the frame body only after the profile parts have been connected to form the frame body. In an optional further process step, the insert or the insert parts can be connected to the profile parts, in particular in a materially bonded manner, preferably in the course of connecting the profile parts to form the basic frame body.

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

Show it:

FIG. 1 outlined representation of an embodiment of a flux frame in a plan view;

FIG. 2 Sketched representation of the flux frame according to FIG. 1 in a sectional view along the sectional plane II-II shown in FIG. 1;

FIGS. 3a-e sketched representations of different configurations of a basic frame body in a sectional view corresponding to the sectional plane II-II drawn in FIG. 1;

FIGS. 4a-c sketched representations of different configurations of an insert part in a plan view;

Figure 5 outlined representation of another

Design of a flux frame in a Sectional view corresponding to section plane II-II shown in FIG. 1;

FIG. 6 sketched representation of a section of a redox flow cell in a sectional view along a sectional plane corresponding to the sectional plane II-II shown in FIG. 1;

FIGS. 7a-b sketched representations of two configurations of a half-cell;

Figure 8 Sketched representation of another

Configuration of a flux frame in a plan view;

FIG. 9 sketched representation of the flux frame according to FIG. 8 in a sectional view along the sectional plane IX-IX drawn in FIG. 8; and

Figure 10 Sketched representation of another

Configuration of the flux frame in a view corresponding to FIG.

In the following description and in the figures, the same reference symbols are used for identical or corresponding features. FIG. 1 shows an embodiment of a flux frame, which is denoted overall by reference number 10 . The flux frame 10 is designed in particular for use in a redox flow cell 12, which is described in detail below and shown in sections in FIG.

The flux frame 10 has a modular structure and comprises a frame base body 14 and an insert 16 arranged in the frame base body 14 (indicated by dashed lines in FIG. 1).

As can be seen from FIG. 1, the basic frame body 14 delimits a central frame opening 18 which defines the actual effective space of the cell 12 (explained in more detail below). The basic frame body 14 consists of a plurality, in the example shown four, profile parts 15-

1, 15-2, 15-3, 15-4 compound. The profile parts 15-1, 15-2, 15-3, 15-4 are produced by way of example and preferably by means of an extrusion process (see below). In the example shown, the basic frame body 14 and the frame opening 18 each have a rectangular basic shape. In this respect, two long profile parts 15-2, 15-4 and two short profile parts 15-1, 15-3 are provided. In the case of configurations that are not shown, however, other polygonal geometries are also conceivable.

As can be seen from Figure 1, the profile parts 15-1, 15-

2, 15-3, 15-4, for example, cut to length at their respective ends 20 to miter and to the frame base body 14 tied together. By way of example and preferably, the profile parts 15-1, 15-2, 15-3, 15-4 are connected to one another in a fluid-tight manner, for example by means of gluing and/or welding.

As can be seen from FIG. 2, the profile parts 15-1, 15-2, 15-3, 15-4 and thus the basic frame body 14 composed of them, viewed in the circumferential direction around the frame opening 18, have a cross-sectional profile that is open on one side in the direction of the frame opening 18 . In the example shown, the cross-sectional profile is essentially U-shaped with a short leg 22 and two long legs 24-1, 24-2.

As can be seen from FIGS. 2 and 3a to 3e, the profile parts 15-1, 15-2, 15-3, 15-4 each delimit an internal profile part receiving space 26', which is open on one side through a profile opening 28. If the profile parts 15 - 1 , 15 - 2 , 15 - 3 , 15 - 4 are assembled to form the basic frame body 14 , a profile receiving space 26 encircling the frame opening 18 and open in the direction of the frame opening 18 is formed.

FIGS. 3a to 3e show further exemplary cross-sectional profiles which the basic frame body 14 can have. For example, the basic frame body 14 can be formed mirror-symmetrically to a frame plane spanned by the frame opening 18 (cf. FIGS. 3a and 3b). It is also possible for the frame base body 14 to have recesses on its outer sides 30, 32 oriented orthogonally to the plane of the frame 70', 72', 82 or projections 78, 84 (cf. FIGS. 3b to 3e, described in detail below). As shown in FIG. 3c, the profile part receiving space 26' can also have an internal step 34.

The frame base body 14 is made, for example and preferably, from a thermoplastic elastomer with a Shore hardness of 50 to 80 Shore A.

As can be seen from FIG. 2, the insert 16 mentioned above is arranged in the profile receiving space 26 of the basic frame body 14 . The insert 16 is formed separately from the frame base body 14 and is inserted into the profile receiving space 26 for assembling the flux frame 10 (explained in more detail below in relation to the manufacturing method).

By way of example and preferably, the insert 16 is made from a more rigid material than the basic frame body 14 , in particular from polypropylene (PP), polyethylene (PE) and/or polyvinyl chloride (PVC).

As can be seen from FIG. 1, the insert 16 is designed, for example, in such a way that it completely surrounds the frame opening 18 . In the example shown, the insert 16 is also dimensioned such that it does not protrude from the profile receiving space 26 and is positively received in the profile receiving space 26 (cf. FIG. 2). As shown in FIG. 2, the insert 16 comprises channel structures 36, explained in more detail below, which are designed to distribute electrolyte liquid in the frame opening 18. The insert 16 can be designed in such a way that channel structures 36 are provided along its entire circumference. By way of example and preferably, however, the channel structures 36 are only arranged on the longitudinal sides 38 - 1 , 38 - 2 of the flux frame 10 .

The insert 16 can be designed in one piece, for example in the form of an insert frame (shown as an example in FIG. 1). In an alternative embodiment, the insert 16 can also be formed from a plurality of separately provided insert parts 16'. These can be inserted separately from one another in the profile receiving space 26 and optionally connected to one another in a fluid-tight manner, in particular in a materially bonded manner.

In principle, the insert parts 16′ can be configured differently. A selection of exemplary configurations of the insert parts 16' is shown in FIGS. 4a to 4c. For example, the inserts 16' can have a trapezoidal (see FIG. 4a) or rectangular (see FIG. 4b) or L-shaped (see FIG. 4c) basic shape. Depending on the requirements, different insert parts 16' can be used and combined with one another. The insert parts 16′ shown in FIGS. 4a to 4c each include the channel structures 36 mentioned above. In the example shown, the channel structures 36 include a fluid connection 40, a fluid guide 42—meandering in the example shown—and comb-shaped distributor structures 44, which open into the frame opening 18 when the insert parts 16′ are installed as intended. This configuration of the channel structures 36, 40, 42, 44, which is only shown as an example for the insert parts 16' in the figures, can also be provided in a corresponding manner in the case of a one-piece design of the insert 16.

The channel structures 36, 40, 42, 44 are, for example and preferably, formed by corresponding recesses 46 on an outer side 48 of the insert 16 or of the insert parts 16' (cf. FIG. 2). When the insert 16 or the insert parts 16' are installed as intended in the profile receiving space 26, the channel structures 36, 40, 42, 44 are then closed by an inner wall 50 of the basic frame body 14 (cf. FIG. 2). In the example shown in FIG. 1, the basic frame body 14 has corresponding bores 52 for feeding the channel structures 36 with electrolyte liquid. As shown by way of example in FIG. 5, the insert 16 or the insert parts 16′ can have optional projections 54-1, 54- on its outer side 48—for sealing the channel structures 36 and/or fluid passages 52, which will be explained in more detail below, with respect to the frame base body 14. 2 such that a channel structure 36 to be sealed between the projections 54-

1, 54-2 is included. When the insert 16 or the insert parts 16' are installed as intended in the profile receiving space 26, the projections 54-1, 54-2 of the insert 16 can then dig into the inner wall 50 of the softer basic frame body 14 and thus provide a sealing effect. It is also possible for the frame base body 14 to have corresponding grooves 56-1, 56-2 on the inner wall 50 of the frame base body 14 facing the profile receiving space 26, in which grooves the projections 54-1, 54-2 engage.

As already mentioned, a flow frame 10 described above is used in particular for use in a redox flow cell 12. A section of a possible embodiment of such a cell 12 is shown in outline in FIG. FIG. 6 shows the cell 12 in a sectional view along a sectional plane corresponding to the sectional plane II-II in FIG.

The cell 12 comprises two half-cells 58-1, 58-2, between which a membrane 60 is arranged. Each half cell 58-1, 58-2 comprises a flux frame electrode unit 62-1, 62-

2, which in turn each have a flux frame 10 and a comprises an electrode 64 arranged in the frame opening 18 of the flux frame 10 (described in detail below with reference to FIGS. 7a and 7b). As can be seen from FIG. 6, in the example shown the flux frames 10 of the two flux frame-electrode units 62-1, 62-2 are identical to one another, but are folded relative to one another by 180° about the membrane plane. The membrane 60 is preferably designed and arranged in such a way that the frame opening 18 and the electrode 64 arranged therein are, in particular completely, covered by the membrane 60 .

In a redox flow battery, a plurality of such cells 12 are preferably stacked on top of one another in a stacking direction 66 to form a cell stack (not shown) and pressed against one another by a bracing system (not shown). In such a cell stack, a bipolar plate 68 is provided between the individual cells, which electrically connects two adjacent cells 12 . Two such bipolar plates 68 are shown in FIG. Preferably, a bipolar plate 68 also completely covers frame opening 18 .

As can be seen from FIG. 7a, which shows a half-cell 58-1 of the cell 12 according to FIG Outside 32 of the frame body 14 is formed. In an analogous manner, in the example shown, the bipolar plate 68 is also arranged in a corresponding bipolar plate receiving area 72 which is formed on the opposite outer side 30 of the basic frame body 14 .

Specifically, the membrane receiving area 70 and the bipolar plate receiving area 72 are formed by a stepped recess 70', 72' viewed in cross section on those outer sides 30, 32 of the frame base body 14 which are oriented parallel to a frame plane spanned by the frame opening 18 (see also FIG. 2). The respective stepped recess 70', 72' adjoins the frame opening 18 and preferably completely surrounds it. As shown in Figures 7a and 2, an edge 74 or 76 is formed by the stepped recesses 70', 72', which extends orthogonally to the frame plane spanned by the frame opening 18 and forms a stop for the membrane 60 or the bipolar plate 68 forms.

By way of example and preferably, the insert 16 and the membrane receiving area 70 or the bipolar plate receiving area 72 are matched to one another in such a way that a membrane 60 or bipolar plate 68 lying against the respective edge 74 or 76 partially overlaps the insert 16 when viewed in the stacking direction 66 ( cf. Figure 7a). As can be seen from FIGS. 3a to 3e, fundamentally different configurations of the frame base body 14 are conceivable with respect to the receiving regions 70 , 72 . The configurations of the receiving areas 70, 72 or Recesses 70', 72' regardless of the other design features of the frame base body 14 specifically shown in the relevant figures (e.g. relative thickness of the legs 24-1, 24-2 or the presence of other contour elements such as projections 78, 84 or recesses 82 ) be provided . In a first embodiment according to FIG. 3a, neither membrane receiving area 70 nor bipolar plate receiving area 72 are provided. membrane 60 or Bipolar plates 69 are then in particular in contact with the two planar outer sides 30 , 32 of the frame base body 14 . In a further embodiment according to FIG. 3b, a stepped recess 70 or 72' is provided, ie both membrane receiving area 70 and bipolar plate receiving area 72. It is also possible for a stepped recess 70', 72' to be provided on only one of the outer sides 30, 32, which then forms either a membrane receiving area 70 or a bipolar plate receiving area 72 (cf. FIGS. 3c and 3d). As shown in FIG. 3e by way of example for a recess 72', within such a stepped recess 70' or 72', a local projection 78 can also be provided, which can serve in particular as a sealing lip and/or positioning aid. Such a projection 78 can be provided in the membrane receiving area 70 and/or in the bipolar plate receiving area 72 .

Two exemplary configurations of a flux frame electrode unit 62 are described below with reference to FIGS. 7a and 7b, which differ only in the specific configuration and arrangement of the electrode 64. FIG. In both cases, the electrode 64 is exemplary and preferably designed as a felt electrode, for example. made from a graphite felt z.

In the embodiment shown in FIG. 7a (corresponds to the embodiment shown in FIG. 6), the electrode 64 is designed and arranged in such a way that it is flush with the inner edges 80 of the frame base body 14 facing the frame opening 18 . Viewed in cross section, the electrode 64 is flush with the free ends 80 of the two long legs 24 - 1 , 24 - 2 of the frame base body 14 . In this respect, the profile opening 28 is closed by the electrode 64 . In the example shown, the insert 16 is dimensioned in such a way that it lies directly against the electrode 64 .

In the embodiment according to FIG. 7b, the electrode 64 is designed and arranged in such a way that it partially penetrates into the profile receiving space 26 of the frame base body 14 and is received there in a form-fitting manner. As can be seen from FIG. 7b, the insert 16 and the electrode 64 are also designed here in such a way that the electrode 64 is in direct contact with the insert 16. To seal flux frames 10 arranged next to one another, for example when used in a cell stack mentioned above, the frame base bodies 14 of the flux frames 10 can be connected to one another in a fluid-tight manner in the manner of tongue and groove. FIG. 3e shows an exemplary configuration of such a tongue and groove connection in cross section. In the example shown, the basic frame body 14 has a groove 82 surrounding the frame opening 18 on a first outer side 32 and a corresponding projection 84 (tongue) surrounding the frame opening on the opposite outer side 30 .

As shown by way of example in FIG. 8, the profile parts 15-2, 15-4 can also be connected to one another via connecting elements 86-1, 86-2. In the example shown, the flux frame 14 is composed of two profile parts 15-2, 15-4 and two connecting parts 86-1, 86-2. The connecting parts 86-1, 86-2 are arranged between the profile parts 15-2, 15-4 and engage with a respective end section 88 in the profile receiving spaces 26' of the profile parts 15-2, 15-4 (in Figure 9a by way of example for a junction shown) . By way of example and preferably, the connecting parts 86-1, 86-2 are cohesively connected to the profile parts 15-2, 15-4. In the example shown in FIG. 8, an insert part 16′-1, 16′-2 is arranged in the profile receiving spaces 26′ of the two profile parts 15-2, 15-4 Channel structures 36 have. For the further configuration of the profile parts 15-2, 15-4 and the insert parts 16'-1, 16'-2, reference is made to the configurations described above.

As shown by way of example in FIG. 10, the connecting parts 86-1, 86-2 can also have connecting contours, for example in the form of connecting pins 90, on their end sections 88. Then the profile parts 15-2, 15-4 preferably each have corresponding recesses 92, in which the connecting pins 90 are positively received when arranged as intended.

An embodiment of a method for producing the flux frame according to FIG. 1 is described below. According to the method, first the profile parts 15-1, 15-2, 15-3, 15-4 and the insert 16 or the insert parts 16' are produced.

In order to produce the profile parts 15-1, 15-2, 15-3, 15-4, a profile strand which has the desired cross-sectional profile (cf. FIGS. 3a to 3e) is first extruded and cut to length according to a desired size of the future frame body 14. To produce the flux frame 10 shown in FIG. 1, two short profile parts 15-1, 15-3 and two long profile parts 15-2, 15-4 are produced, for example. The respective ends 20 of the profile parts 15-1, 15-2, 15-3, 15-4 connecting contours 21 are then produced (cf. FIG. 1). By way of example and preferably, the connection contours 21 are produced in that the profile parts 15-1, 15-2, 15-3, 15-4 are mitred to length at their ends 20, for example by cutting or punching. In an optional further step, at least in a subset of the profile parts 15-1, 15-2, 15-3, 15-4 - to produce the embodiment shown in Figure 1, in the long profile parts 15-2, 15-4 - recesses 52 generated for the electrolyte supply, for example by drilling or punching.

The insert 16 or the inserts 16′ are produced, for example, by primary shaping, reshaping, cutting or by injection molding processes.

The profile parts 15-1, 15-2, 15-3, 15-4 and the insert 16 or the insert parts 16' are then assembled to form the flux frame 10. For this purpose, the insert 16 or the insert parts 16' are first inserted into the profile part receiving spaces 26' of the profile parts 15-1, 15-2, 15-3, 15-4. In a further process step, the profile parts 15-1, 15-2, 15-3, 15-4 are connected at their ends 20 to the frame base body 14 in a fluid-tight manner, for example by welding and/or gluing. Optionally, in the same work step, the inserts 16' can also be cohesively connected to one another and/or to the profile parts 15-1, 15-2, 15-3, 15-4. In an alternative embodiment of the method, the insert parts 16′ can also be inserted into the profile receiving space 26 only after the profile parts 15-1, 15-2, 15-3, 15-4 have been connected.

To produce the flux frame shown in Figure 8

10, two profile parts 15-2, 15-4 and two insert parts 16'-1, 16'-2 are first produced in the manner described above. In addition, the connecting parts 86-1, 86-2 are produced, for example by means of an injection molding process. To the

When mounting the frame base body 14, the insert parts 16'-1, 16'-2 are then first inserted into the profile part receiving spaces 26' of the profile parts 15-2, 15-4 and then the profile parts 15-2, 15-4 with the connecting parts 86 -1, 86-2 joined together and connected to each other in a cohesive manner.

Claims

Claims Modular flow frame (10) for an electrochemical cell (12), in particular for a cell (12) of a redox flow battery, comprising

- a basic frame body (14) which defines a frame opening (18), wherein the basic frame body (14) has a cross-sectional profile which is open on one side in the direction of the frame opening (18) and is preferably essentially U-shaped, so that a ) toward open profile receiving space (26) is formed;

- An insert (16) which is arranged in the profile receiving space (26) of the frame base body (14), the insert (16) having channel structures (36) for the distribution of fluids in the frame opening (18). A flux frame (10) according to claim 1, wherein said frame body (14) comprises a plurality of extruded profile parts (15-1, 15-2, 15-3, 15-4), said profile parts (15-1, 15-2, 15-3, 15-4) each delimit a profile part receiving space (26'), in particular the profile parts (15-1, 15-2, 15-3, 15-4) having the same cross-sectional profile. 43 flux frame (10) according to claim 2, wherein the frame body (14) two profile parts (15-2, 15-4) and two the profile parts (15-2, 15-4) interconnecting connecting parts (86-1, 86-2 ) Includes, wherein the connecting parts (86-1, 86-2) with a respective end portion (88) in the

Profile parts receiving spaces (26') of the profile parts (15-2, 15-4) engage. Flux frame (10) according to one of claims 2 or 3, wherein the profile parts (15-1, 15-2, 15-3, 15-4) with each other and/or the profile parts (15-2, 15-3) with the connecting parts (86-1, 86-2) are fluid-tightly connected. Flux frame (10) according to one of the preceding claims, wherein the channel structures (36, 40, 42, 44) of the insert (16) are formed by recesses (46) on the outside (48) of the insert (16). Flow frame (10) according to one of the preceding claims, wherein the insert (16) has sealing contours (54-1, 54-2) on its outer side (48) for sealing, in particular the channel structures (36), against the frame base body (14), in particular wherein the basic frame body (14) has corresponding counter-seal contours (56-1, 56-2). Flux frame (10) according to any one of the preceding claims, wherein the frame body (14) is made of an elastomer, preferably of a 44 thermoplastic elastomer, more preferably made of thermoplastic polyethylene (TPE), thermoplastic polystyrene (TPS), thermoplastic polyurethane (TPU) and / or of a thermoplastic vulcanizate (TPV). Flow frame (10) according to one of the preceding claims, wherein the insert (16) is made of a plastic that is harder and/or stiffer, in particular compared to the material of the frame base body, preferably of a thermoplastic plastic, more preferably of polypropylene (PP), Polyethylene (PE) and/or polyvinyl chloride (PVC) . Flux frame (10) according to one of the preceding claims, wherein the insert (16) is designed in multiple parts, comprising at least two insert parts (16 '), in particular wherein the insert parts (16') to an insert frame cohesively and / or positively, preferably via a groove -and- spring connections, are connected. Flux frame (10) according to Claim 8, in which the basic frame body (14) has a rectangular basic shape and in which those insert parts (16') which are arranged on the longitudinal sides (38-1, 38-2) of the basic frame body (14) have channel structures ( 36) for distributing a fluid in the frame opening (18). Flow frame (10) according to any one of the preceding claims, wherein the frame body (14) at least on one those outer sides (30, 32) which are oriented parallel to a frame plane spanned by the frame opening 18, in particular on both opposite outer sides (30, 32) , a stepped recess (70', 72 ') having. Flow frame electrode unit (62-1, 62-2), comprising a flow frame (10) according to any one of the preceding claims and one, preferably the frame opening

(18) filling electrode (64), in particular the electrode (64) being designed and arranged in such a way that the electrode (64) is flush with the inner edges (80) of the frame base body (14) facing the frame opening (18) or the electrode (64) being designed and arranged in such a way that the electrode (64) partially penetrates into the profile receiving space (26) of the frame base body (14). Cell (12) for a redox flow battery, comprising a first and a second flux frame electrode unit (62-1, 62-2) according to claim 12, wherein between the first and the second flux frame electrode unit (62 -1, 62-2) a membrane (60) is arranged, in particular wherein the flux frame (10) of the second flux frame-electrode unit (62-2) is relative to the flux frame (10) of the first flux frame-electrode unit (62 -1) is folded 180° around one of its outer edges. Cell stack for a redox flow battery, comprising a plurality of cells (12) according to claim 13, wherein the cells (12) are stacked on top of one another along a stacking direction (66), in particular wherein a bipolar plate (68) is arranged and wherein the bipolar plates (68) and/or the membranes (60) are designed and arranged in such a way that, when viewed in the stacking direction (66), they are in a direction orthogonal to the stacking direction (66) with the respective insert (16) of the adjoining flux frame electrode units (62-1, 62-2) partially overlap, in particular with an overlap being 1 to 40 mm, preferably 5 to 15 mm. Method for producing a flux frame (10) according to one of Claims 1 to 11, comprising the following steps: a) providing a plurality of profile parts (15-1, 15-2, 15-3, 15-4), wherein a profile strand is extruded which has a cross-sectional profile that is open on one side and is preferably essentially U-shaped, so that a profile part receiving space (26') that is open on one side is formed, and wherein the profile strand for forming the profile parts (15-1, 15-2, 15-3 , 15-4) is cut to length; b) placing the insert (16) or the insert parts (16') in the profile part receiving spaces (26') of the profile parts (15-1, 15-2, 15-3, 15-4); 47 c) Fluid-tight, in particular cohesive, connection of the profile parts (15-1, 15-2, 15-3, 15-4) to connection sections (21, 88, 90, 92).