REDOX FLOW CELL AND METHOD FOR ITS ASSEMBLY AS WELL AS REDOX FLOW BATTERY

Description

[0001] The present invention relates to a redox flow cell with an electrode module and a membrane module. The electrode module comprises an electrode frame in which an electrode is arranged. The membrane module comprises a membrane frame with a membrane firmly seated therein. The invention further relates to a redox flow battery and a method for assembling a redox flow cell, wherein the assembly simultaneously leads to the sealing of an electrode in an electrode module of the redox flow cell.

[0002] Electrical cells known as redox flow cells are known from the prior art and can be used to form redox flow batteries. In the term "redox," "red" stands for reduction, which involves the uptake of electrons, while "ox" stands for oxidation, which involves the loss of electrons. Redox flow cells store electrical energy in chemical compounds by dissolving the reactants in a solvent. Two energy-storing electrolytes circulate in two separate circuits, between which ion exchange takes place within the cell via a membrane. The energy-storing electrolytes are preferably stored outside the cell in separate tanks.

[0003] Redox flow cells preferably have an electrode frame that surrounds a metallic electrode of the cell. The electrode frame provides a support frame for the electrode and also serves as a seal. A circumferential seal is required between the electrode frame and the electrode. Since the electrolyte to be sealed is chemically aggressive, the choice of sealing material is limited. The typically thin walls of the electrode frame and the electrode also restrict the choice of a suitable sealing system. Sealing solutions that utilize conventional molded seals are known from the prior art. These molded seals are typically secured by a groove in the electrode frame. For a force-fitting connection, an undercut groove in the electrode frame is required, which, due to the closed circumferential groove, increases manufacturing complexity.Since the electrode frame typically has a wall thickness of less than 3 mm, a form-fitting groove connection is hardly feasible due to its delicate design. State-of-the-art sealing solutions also include so-called formed-in-place (FIP) seals, which are applied using dispensing processes that often prove economically unviable due to relatively long cycle times. Furthermore, the geometry of the sealing profile can only be influenced to a limited extent. Sealing systems with formed-in-place and FIP seals require an additional element to generate the seal preload. Sealing compounds with elastic adhesives are also used. Due to the chemical aggressiveness of the electrolyte, leaching of the adhesive can occur.In addition, the significantly different thermal expansion rates of the thermoplastic electrode frame and the metallic electrode lead to significant shear stresses in the adhesive bead, especially in large formats. Both effects significantly reduce the service life of such a sealing system.

[0004] EP 2 693 087 A1 discloses a sealing material for a thin plate element, such as in a cell of a redox flow battery. The annular sealing material comprises a lateral sealing body arranged on one side of the thin plate element. The front and rear sides of the thin plate element are arranged on two sealing legs branching off from the lateral sealing body.

[0005] WO 2014 / 198364 A1 shows an electrode module for a redox flow battery. The electrode module comprises an electrode and a sealing frame. The electrode is to be connected to the sealing frame in such a way that the resulting electrode module can be easily used in redox flow cells. For this purpose, the electrode is mechanically connected to the sealing frame. A multi-lip seal is preferably arranged on the sealing frame, which rests against a membrane. The sealing frame preferably has a circumferential groove that tapers conically towards the outside. The groove preferably has an undercut.

[0006] WO 2013 / 016919 A1 shows a flow battery stack with a flow frame and a collector plate arranged within the flow frame. An ion exchange membrane is arranged between the collector plates, forming a cavity in which an electrolyte is housed with the collector plate. An electrode is arranged within the cavity. Two groups of flow openings are formed on the sides of the flow frame.

[0007] EP 2 432 043 A1 discloses a sealing frame for use in a battery, which has a base body enclosing an opening. A triggering region is formed at one edge of the opening. Adjacent to the triggering region, a continuous discharge opening is formed in the base body. A cell with a cell housing is surrounded by a sealing seam. The cell is placed against the sealing frame such that the cell housing extends into the opening in order to apply the sealing seam to the seal, wherein in the triggering region, the sealing seam is not subjected to the seal. At least one circumferential, elastically compressible seal is provided, which encompasses the opening.

[0008] EP 3 113 272 A1 discloses a frame body for a cell of a redox flow battery. The frame body comprises an opening formed within the frame body and a distributor through which an electrolyte can pass. A slot connecting the distributor and the opening has a pair of sidewalls that oppose each other in a cross-section orthogonal to a direction in which the electrolyte flows.

[0009] The applicant's German patent application No. 10 2021 105 597.0, which was still unpublished at the time of filing, shows an electrode module for a redox flow cell. This electrode module comprises a frame with a circumferential seal arranged on an inner circumference of the frame, which seal has at least two inwardly directed elastic sealing lips. A circumferential groove is formed between two of the sealing lips. The electrode module also comprises an electrode having an outer circumference, with which the electrode sits in the groove of the seal. Furthermore, a redox flow cell and a method for assembling an electrode module for the redox flow cell are described.

[0010] The object of the present invention, based on the prior art, is to provide a construction and a method for assembly in order to be able to fix an electrode of a redox flow cell tightly and securely in an electrode frame.

[0011] The stated object is achieved by a redox flow cell according to the appended claim 1, by a redox flow battery according to the appended independent claim 9 and by a method according to the appended independent claim 10.

[0012] The redox flow cell according to the invention is a wet cell and thus an electrical accumulator. The redox flow cell stores electrical energy in chemical compounds, with the reactants dissolved in a solvent in two energy-storing electrolytes. The two energy-storing electrolytes circulate in two separate circuits, between which an ion exchange takes place in the cell through a membrane. The redox flow cell is preferably formed by an organic flow cell made of non-toxic components. The redox flow cell is defined by at least one electrode, which is formed in an electrode module.

[0013] The electrode module of the redox flow cell comprises an electrode frame, which forms a support frame and also a sealing frame. For this purpose, the electrode frame comprises a seal, which is arranged on an inner circumference of the electrode frame. The seal is formed circumferentially on this inner circumference of the electrode frame and directed inwards. The seal has at least one holding frame and a first elastic sealing lip. The holding frame is preferably oriented in a direction perpendicular to a main extension plane of the electrode frame, with one side surface of the holding frame facing inwards, i.e. towards a central axis of the electrode frame, which is oriented perpendicular to the main extension plane of the electrode frame. The holding frame has, on its inner circumference, an at least partially circumferential snap-in nose for circumferentially receiving an electrode.The snap-in lug is preferably formed on the inward-facing side surface of the holding frame so that it is aligned with the central axis of the electrode frame. The holding frame is preferably, but not necessarily, completely circumferential, so that it has a frame-like shape. The snap-in lug is preferably completely circumferential or, alternatively, preferably circumferential with interruptions, whereby the electrode can be snapped into the seal with less force during assembly. The elastic snap-in lug allows slight displacements and temperature-related changes in size of the electrode in the main extension plane of the electrode. The first elastic sealing lip is arranged within the inner circumference of the holding frame so that it describes a smaller circumference than the holding frame. The first elastic sealing lip is designed for lateral sealing and lateral support of the electrode.The first elastic sealing lip is preferably also oriented in a direction perpendicular to the main extension plane of the electrode frame. The first elastic sealing lip preferably runs parallel to the holding frame. The holding frame lies in a plane which is preferably oriented parallel to a plane in which the first elastic sealing lip lies and which is also parallel to the main extension plane of the electrode frame. With respect to an axis which is arranged perpendicular to the main extension plane of the electrode frame, the first elastic sealing lip is arranged axially offset from the holding frame, such that the electrode can be received axially between the holding frame and the first elastic sealing lip.The preferably plate-shaped electrode forms a component of the electrode module and has an outer periphery with which the electrode is snapped behind the snap-in lug of the holding frame, whereby the electrode is pressed laterally against the first sealing lip. The snap-in lug is pressed against an outer periphery and against a first side surface of the electrode, while the first elastic sealing lip is pressed against a second side surface of the electrode, which is opposite the first side surface. The first elastic sealing lip preferably lies completely against the electrode. The electrode is preferably metallic. The electrode is held and fixed by the holding frame and the first elastic sealing lip and sealed at least by the first sealing lip. The electrode lies in one plane together with the electrode frame. This plane represents the main extension plane of the electrode frame, the seal, and the electrode.The seal encloses the electrode. The electrode frame encloses the seal and the electrode inside. The seal is resistant to the chemically aggressive electrolytes of the redox flow cell.

[0014] The redox flow cell also comprises a membrane module firmly connected to the electrode module. The membrane module comprises a membrane frame and a membrane firmly seated in the membrane frame. The membrane is preferably welded into the membrane frame. The membrane lies in the same plane as the membrane frame. This plane represents the main extension plane of the membrane frame and the membrane. The electrode module and the membrane module are preferably firmly connected to one another by firmly connecting the electrode frame of the electrode module and the membrane frame of the membrane module, with the electrode frame and the membrane frame being arranged in alignment with one another.

[0015] The electrode is clamped or pressed between at least partially circumferentially arranged pressure elements of the membrane frame, on the one hand, and the first elastic sealing lip of the seal of the electrode frame, on the other hand. The pressure elements are arranged at least partially circumferentially around the central axis of the electrode frame, namely axially indirectly adjacent to the first sealing lip. With respect to the central axis of the electrode frame, the electrode is arranged axially between the circumferentially arranged pressure elements of the membrane frame, on the one hand, and the first elastic sealing lip of the seal of the electrode frame, on the other hand. The circumferentially arranged pressure elements of the membrane frame are preferably formed by pronounced features of the membrane frame, which, in the case of the preferably rectangular electrode, are present on each of the four sides of the rectangle.The circumferentially arranged pressure elements of the membrane frame are preferably formed by raised domes. The circumferentially arranged pressure elements are preferably not circumferentially closed in their entirety in order to form flow channels for an electrolyte.

[0016] A particular advantage of the redox flow cell is that the seal, together with the pressure elements of the membrane frame, enables both sealing of the electrode and its secure storage. The electrode can be quickly and easily mounted in the electrode frame, with a preload force already generated by the seal itself. The electrode can also be removed from the electrode frame if necessary.

[0017] In preferred embodiments, the pressing elements are pressed against an upper side of the preferably plate-shaped electrode, while the first elastic sealing lip is pressed against an underside of the electrode. The electrode is thus force-fitted between the pressing elements on the one hand and the first elastic sealing lip on the other. This leads to the advantage that the electrode is fixed in a direction perpendicular to its main plane of extension and is also securely sealed. The snap-in nose presses against the outer circumference of the electrode and also at least slightly against the upper side of the electrode.

[0018] The snap-in tab allows the electrode to be mounted into the electrode frame with minimal effort, whereby the above-described preferred orientation of the holding frame in a direction perpendicular to the main extension plane of the electrode frame ensures that the holding frame, with the snap-in tab formed thereon, springs back. The snap-in tab formed on the holding frame preferably rests completely circumferentially on the electrode, so that the snap-in tab holds the electrode and, in special embodiments, additionally seals it.

[0019] The first elastic sealing lip preferably has a plurality of sealing lugs configured to extend completely around the circumference. The sealing lugs bear completely against the electrode. The sealing lugs preferably lie together in a plane that is parallel to the main extension plane of the electrode frame. With respect to an axis that is arranged perpendicular to the main extension plane of the electrode frame, the sealing lugs are preferably arranged radially next to one another and coaxially. The sealing lugs have different circumferences. The formation of the plurality of sealing lugs increases the sealing effect of the first sealing lip with respect to the electrode. The sealing lugs are preferably arranged axially next to the contact pressure elements of the membrane frame. The sealing lugs preferably each have a flat, rounded, triangular, or pointed cross-section. The first elastic sealing lip preferably has three of the circumferential sealing lugs.A middle sealing lug forms a primary sealing path, and the two outer sealing lugs form a secondary sealing path. The middle sealing lug preferably has a rounded cross-section. The two outer sealing lugs preferably have a flat cross-section, so that they are pressed against the electrode with a larger surface area than the middle sealing lug, creating a large sealing surface while also smoothing out any unevenness in the electrode.

[0020] The seal preferably has a second elastic sealing lip, which is arranged between the holding frame and the first elastic sealing lip. The second elastic sealing lip is designed to be circumferential and preferably lies completely against the electrode. The second elastic sealing lip is preferably designed to be completely circumferential around the central axis of the electrode frame. With respect to the central axis of the electrode frame, the second elastic sealing lip is arranged in the radial direction between the holding frame and the first elastic sealing lip. The second elastic sealing lip and the first elastic sealing lip preferably lie together in a plane which is parallel to the main extension plane of the electrode frame.

[0021] In a further developed embodiment, the seal has a third elastic sealing lip, which is arranged within an inner circumference of the first elastic sealing lip. The third elastic sealing lip is designed to be circumferential and preferably lies completely against the electrode. The third elastic sealing lip is preferably designed to be completely circumferential around the central axis of the electrode frame. With respect to the central axis of the electrode frame, the third elastic sealing lip is arranged radially inward next to the first elastic sealing lip. The third elastic sealing lip and the first elastic sealing lip preferably lie together in a plane which is parallel to the main extension plane of the electrode frame.

[0022] According to a preferred embodiment, the second elastic sealing lip and / or the third elastic sealing lip form tertiary sealing paths. The second elastic sealing lip and the third elastic sealing lip are preferably located radially on either side of the first elastic sealing lip. The second elastic sealing lip and / or the third elastic sealing lip increase the sealing effect of the seal against the electrode and the force on the electrode against the contact elements of the membrane frame. The second elastic sealing lip and / or the third elastic sealing lip are preferably each oriented opposite an electrolyte to be sealed.

[0023] In preferred embodiments, the seal is attached to the inner circumference of the electrode frame in a form-fitting and / or material-fitting manner. This attachment ensures secure fixation and sealing of the electrode seated in the seal against the electrode frame.

[0024] In particularly preferred embodiments, the seal is attached as an injection-molded part to the inner circumference of the electrode frame. This ensures that the seal is positively and firmly bonded to the inner circumference of the electrode frame.

[0025] The electrode frame preferably has a stop on its inner circumference that laterally delimits the inner circumference. The stop is preferably formed circumferentially around the inner circumference. The stop forms a support for the seal. A circumferential concave edge is preferably formed between the inner circumference and the stop. The inner circumference is preferably formed such that a dropped solder on the circumference lies in the main extension plane of the electrode frame. The stop is preferably aligned perpendicular to the inner circumference of the electrode frame such that the circumferential concave edge has an angle of 90°. The seal is preferably seated in the circumferential concave edge. The circumferential concave edge ensures secure and tight fixation of the seal in the electrode frame.

[0026] In modified embodiments, the seal is introduced as an injection-molded part into the circumferential concave edge of the electrode frame, whereby it is firmly and tightly connected to the electrode frame.

[0027] The seal is preferably elastic and preferably made of a polymer. The polymer is particularly preferably a thermoplastic elastomer (TPE), an ethylene propylene diene rubber (EPDM), or a fluororubber (FKM). The seal or polymer is preferably acid-resistant.

[0028] The electrode frame is preferably made of a plastic, particularly preferably a thermoplastic. The electrode frame is preferably acid-resistant.

[0029] The membrane frame is preferably made of a plastic, particularly preferably a thermoplastic. The membrane frame is preferably acid-resistant.

[0030] The metallic electrode preferably consists of a copper-zinc alloy or graphite. However, the electrode can also be made of another metal. The electrode is preferably porous. The electrode is preferably formed by a thin-walled structure. The electrode preferably has the shape of a rectangular plate. In this respect, the electrode has the shape of a flat cuboid.

[0031] The membrane is preferably made of a plastic. The membrane is preferably microporous and forms an ion-selective separator. The membrane is preferably in the shape of a rectangular plate. In this respect, the membrane has the shape of a flat cuboid.

[0032] The redox flow battery according to the invention comprises a plurality of the redox flow cells according to the invention. The redox flow cells are preferably arranged in alignment with one another. Thus, the membrane modules and the electrode modules of all the redox flow cells are preferably arranged in alignment with one another. One of the membrane modules is arranged between two of the electrode modules. Electrolytes can circulate between the electrodes. The redox flow cells are preferably designed identically. The redox flow cells of the redox flow battery are preferably designed according to one of the preferred embodiments described above.

[0033] The method according to the invention is used to assemble a redox flow cell. In one step of the method, a metallic electrode for the redox flow cell is provided. In addition, an electrode frame for the electrode, into which the electrode is to be inserted, is provided. The electrode frame comprises a seal arranged on an inner circumference of the electrode frame and formed circumferentially. The seal has at least one holding frame and a first elastic sealing lip. On an inner circumference of the holding frame, an at least partially circumferential snap-in nose is formed for circumferentially receiving the electrode. The first sealing lip is arranged within the inner circumference of the holding frame and formed for lateral sealing and lateral support of the electrode. In a further step, the electrode is pressed into the seal over the snap-in nose.For this purpose, the electrode is placed over the electrode frame and a force is exerted on the electrode in a direction perpendicular to the main plane of extension. The outer circumference of the electrode snaps behind the snap-in lug of the holding frame and is thus pressed laterally against the first elastic sealing lip. The electrode frame and the electrode inserted therein form an electrode module of the redox flow cell to be assembled. A membrane module is also provided. The membrane module comprises a membrane frame and a membrane. The membrane sits firmly in the membrane frame. The membrane frame has circumferentially arranged pressure elements. In a further step, the electrode module and the membrane module are firmly connected to one another, whereby the electrode is clamped between the circumferentially arranged pressure elements of the membrane frame on the one hand and the first elastic sealing lip of the seal of the electrode frame on the other.

[0034] The redox flow cell to be assembled is preferably the redox flow cell according to the invention described above or one of the preferred embodiments of the redox flow cell according to the invention described above.

[0035] In this respect, the electrode to be provided for the process, the electrode frame to be provided for the process and the membrane module to be provided for the process preferably also have the features described in connection with the redox flow cell according to the invention.

[0036] Further details, advantages, and developments of the invention will become apparent from the following description of a preferred embodiment of the invention, with reference to the drawings. They show: Fig. 1 shows an illustration of a section of a preferred embodiment of a method according to the invention for assembling a redox flow cell; Fig. 2 shows a first step of theFig. 1 illustrated section of the method; Fig. 3 a second step of the Fig. 1 illustrated section of the method; Fig. 4 a third step of the Fig. 1 illustrated section of the method; Fig. 5 a step of a further section of the method; and Fig. 6 the in Fig. 1 to Fig. 5 Redox flow cell assembled using the method illustrated.

[0037] Fig. 1 illustrates a section of a preferred embodiment of a method according to the invention for assembling a redox flow cell. In this section, an electrode module of the redox flow cell is assembled. First, a rectangular electrode frame 01 and a rectangular electrode 02 are provided. The electrode frame 01 has a circumferentially formed elastic seal 03 (shown in Fig. 2 ) on.

[0038] A broad, horizontal arrow 04 symbolizes the sequence of this section of the method, in which the electrode 02 is pressed into the electrode frame 01, resulting in an electrode module 10. The electrode module 10 forms a component of a preferred embodiment of a redox flow cell according to the invention (shown in Fig. 6 ). The sequence of this section of the procedure, symbolized by the arrow 04, is described in individual steps in the Figures 2 to 5 shown for a section AA.

[0039] Fig. 2 shows a first step of the Fig. 1illustrated method. In this step, the provided electrode frame 01 and the provided electrode 02 are present. The electrode 02 has been positioned centrally above the electrode frame 01. The sectional view of the electrode frame 01 shows a cross-section of the inner circumferential seal 03. The seal 03 is attached to the inner circumference of the electrode frame 01, which is delimited on one side by a stop 06, by injection molding, in a material-to-material manner to the electrode frame 01 and the stop 06.

[0040] The seal 03 comprises a holding frame 07. The holding frame 07 has a partially circumferential snap lug 08 on its inner circumference for circumferentially receiving the electrode 02. The seal 03 also comprises a first elastic sealing lip 09, which is circumferential and has a central circumferential sealing lug 12 and two outer circumferential sealing lugs 13. The central sealing lug 12 has a rounded cross-section. The two outer sealing lugs 13 have a flat cross-section. The seal 03 also comprises a second elastic sealing lip 14, which is circumferential and is arranged between the first elastic sealing lip 07 and the first elastic sealing lip 09. The seal 03 further comprises a third elastic sealing lip 16, which is circumferential and is arranged within an inner circumference of the first elastic sealing lip 09.

[0041] Fig. 3shows a second step of the Fig. 1 The electrode 02 has already been partially pressed into the seal 03, namely into the snap-in lug 08 of the surrounding holding frame 07, so that the holding frame 07 is slightly sprung outward.

[0042] Fig. 4 shows a third step of the Fig. 1 The method illustrated above. The electrode 02 has been pressed further into the seal 03, so that the snap-in lug 08 of the holding frame 07 is snapped over the electrode 02, so that the electrode 02 is pressed with its underside against the first elastic sealing lip 09, against the second elastic sealing lip 14, and against the third elastic sealing lip 16. The electrode module 10 is thus assembled.

[0043] Fig. 5 shows a step of a further section of the method, which corresponds to the Fig. 1 to Fig. 4illustrated section of the method follows. In this step, a membrane module 20 is placed on the electrode module 10 in order to connect the membrane module 20 to the electrode module 10. The membrane module 20 comprises a membrane frame 21 and a membrane 22, which sits firmly in the membrane frame 21. The membrane frame 21 has circumferentially arranged pressure elements 23 in the form of domes. When the membrane module 20 is placed on the electrode module 10, the pressure elements 23 abut the electrode 02, so that the latter is clamped between the pressure elements 23 and the first elastic sealing lip 09. The result is the assembled redox flow cell.

[0044] Fig. 6 shows the according to the Fig. 1 to Fig. 5Redox flow cell assembled according to the method illustrated. The electrode 02 is snapped behind or below the snap-in nose 08, so that the electrode 02 is fixed by the holding frame 07. The electrode 02 is sealed by the first elastic sealing lip 09, the second elastic sealing lip 14, and the third elastic sealing lip 16.

[0045] A dashed, slightly curved arrow 24 symbolizes the flow and pressure effect of a first medium (not shown) flowing through the redox flow cell during operation. This pressure effect increases, among other things, the sealing effect of the second elastic sealing lip 14. A dashed arrow 26, sharply curved at the end, symbolizes the flow and pressure effect of a second medium (not shown) flowing through the redox flow cell during operation. This pressure effect increases, among other things, the sealing effect of the third elastic sealing lip 16. List of reference symbols

[0046] 01 Electrode frame 02 Electrode 03 Seal 04 Arrow 05- 06 Stop 07 Holding frame 08 Snap-in nose 09 First elastic sealing lip 10 Electrode module 11- 12 Middle sealing nose 13 Outer sealing noses 14 Second elastic sealing lip 15- 16 Third elastic sealing lip 17- 18- 19- 20 Membrane module 21 Membrane frame 22 Membrane 23 Contact elements 24 Arrow 25- 26 Arrow

Claims

1. A redox flow cell, comprising: - an electrode module (10), which comprises an electrode frame (01) having a seal (03) extending around its inner circumference, wherein the seal (03) has at least one holding frame (07) and a first resilient sealing lip (09); wherein an at least partially circumferential snap-action catch (08) for receiving an electrode (02) is formed on the inner circumference of the holding frame (07); wherein the first resilient sealing lip (09) is arranged within the inner circumference of the holding frame (07) and is designed for sealing and supporting the electrode (02); and wherein the electrode module (10) further comprises the electrode (02), the outer circumference of which is snapped behind the snap-action catch (08) of the first resilient sealing lip (07), so that the electrode (02) is pressed against the first resilient sealing lip (09); and - a membrane module (20) connected to the electrode module (10), which comprises a membrane frame (21) and a membrane (22), wherein the membrane (22) is firmly seated in the membrane frame (21); wherein the electrode (02) is clamped between circumferentially arranged pressing elements (23) of the membrane frame (21) and the first resilient sealing lip (09) of the seal (03) of the electrode frame (01).

2. The redox flow cell according to claim 1, characterised in that the pressing elements (23) are pressed against an upper side of the electrode (02) and in that the first resilient sealing lip (09) is pressed against an underside of the electrode (02).

3. The redox flow cell according to claim 1 or 2, characterised in that the first resilient sealing lip (09) has a plurality of circumferentially formed sealing catches (12, 13).

4. The redox flow cell according to any one of claims 1 to 3, characterised in that the seal (03) comprises a second resilient sealing lip (14) that is formed circumferentially and is arranged between the holding frame (07) and the first resilient sealing lip (09).

5. The redox flow cell according to any one of claims 1 to 4, characterised in that the seal (03) comprises a third resilient sealing lip (16) that is formed circumferentially and is arranged inside the inner circumference of the first resilient sealing lip (09).

6. The redox flow cell according to any one of claims 1 to 5, characterised in that the seal (03) is attached in a form-fitting and / or material-fitting manner to the inner circumference of the electrode frame (01).

7. The redox flow cell according to any one of claims 1 to 6, characterised in that the seal (03) is attached to the inner circumference of the electrode frame (01) as an injection-moulded part.

8. The redox flow cell according to any one of claims 1 to 7, characterised in that the electrode frame (01) has on its inner circumference a stop (06) laterally delimiting the inner circumference, wherein a circumferential concave edge is formed between the inner circumference and the stop (06), the seal (03) being seated in said edge.

9. A redox flow battery comprising a plurality of redox flow cells according to any one of claims 1 to 8, wherein one of the membrane modules (20) is arranged respectively between two of the electrode modules (10).

10. A method for installing a redox flow cell, comprising the following steps: - providing an electrode (02); - providing an electrode frame (01) for the electrode (02), which comprises a seal (03) extending around an inner circumference of the electrode frame (01), wherein the seal (03) has at least one holding frame (07) and a first resilient sealing lip (09); wherein an at least partially circumferential snap-action catch (08) for receiving an electrode (02) is formed on the inner circumference of the holding frame (07); wherein the first resilient sealing lip (09) is arranged within the inner circumference of the holding frame (07) and is designed for sealing and supporting the electrode (02); - pressing the electrode (02) over the snap-action catch (08) of the holding frame (07), so that the electrode (02) snaps with its outer circumference behind the snap-action catch (08) of the holding frame (07) and the electrode (02) is pressed laterally against the first resilient sealing lip (09), so that the electrode frame (01) and the electrode (02) introduced therein form an electrode module (10); - providing a membrane module (20) which comprises a membrane frame (21) and a membrane (22), wherein the membrane (22) is firmly seated in the membrane frame (21), and wherein the membrane frame (22) has circumferentially arranged pressing elements (23); and - connecting the electrode module (10) to the membrane module (20), so that the electrode (02) is clamped between the pressing elements (23) of the membrane frame (21) and the first resilient sealing lip (09) of the seal (03) of the electrode frame (01).