Redox flow stack with a one-piece frame and production method

Abstract

The invention relates to a redox flow stack (01). The stack (01) comprises a left and a right terminating element and a plurality of redox flow cells (11) arranged between these terminating elements. Each redox flow cell (11) has a left and a right cell chamber (13, 14), with corresponding electrodes (17, 18) and cell frames (15, 16), and a cell membrane (12) which separates the cell chambers (13, 14). In addition, there are cell separating elements (19) between adjacent cell chambers (13, 14). The innovation is that all the cell frames (15, 16) consist of a one-piece stack frame (02) produced by means of additive manufacturing.

Description

2024PF00388 Foreign version 1 Description TITLE Redox flow stack with one-piece frame and manufacturing process TECHNICAL AREA

[0001] The invention relates to a redox flow stack with multiple redox flow cells for use in a redox flow battery, wherein the cell frames are rigidly connected to one another. The invention further relates to a method for manufacturing such a redox flow stack. BACKGROUND

[0002] A redox flow stack is an essential component of a redox flow battery, which is an electrochemical energy storage system where the storage process is based on redox reactions. The term "redox flow stack" refers to the fact that a redox flow battery uses two electrolytes that circulate in separate circuits and react with each other within the stack. Redox flow technology enables the flexible storage of large amounts of electrical energy and is particularly interesting for integrating renewable energies into the power grid, as the actual storage of the electrically charged electrolytes takes place in arbitrarily scalable tanks, separate for the two circuits.

[0003] A redox flow stack consists of several redox flow cells connected in series. Each redox flow cell contains two electrodes separated by an ion barrier (e.g., a polymer membrane). The electrolytes stored in the tanks are pumped through the cells. The redox reaction takes place at the electrodes, with electrons being transferred between the electrolytes, thus storing or releasing electrical energy. 2024PF00388 Foreign version 2. The individual redox flow cells are always formed by two cell chambers separated by a membrane and surrounded by cell frames. The electrodes are usually located within the cell chambers. Two adjacent redox flow cells are typically separated by a separating layer, which generally extends over the entire surface, including the cell frames.

[0005] Due to the necessity of using multiple redox flow cells for the appropriate dimensioning of a redox flow stack, prior art redox flow stacks are formed by alternately stacking cell frames, separators, and membranes. The cohesion of the arrangement is ensured by tensioning via external tie rods. Furthermore, there are proposals to weld or glue separating elements or membranes to the respective cell frames. It is also suggested that the individual redox flow cells are initially formed by welding or gluing adjacent cell frames together. Regardless of the specific implementation in the prior art, it is always necessary to stack a number of elements on top of each other. Therefore, greater effort is required with regard to handling the elements and the resulting redox flow stack, as well as the typically necessary external clamping of the redox flow stack. Furthermore, a complicating factor is that electrodes are often used which are designed as three-dimensional grids or meshes and are clamped on both sides in the cell chambers for secure electrical contact (i.e., the initial height of the electrodes is greater than the thickness of the cell chambers).

[0009] To simplify the manufacturing process, the use of an additive manufacturing process is described in DE 102016007973 A1 and DE 112019001894 T5. 2024PF00388 Foreign version 3. This involves the sequential additive construction of the cell frames of the individual redox flow cells. This eliminates the otherwise existing problem of sealing between the individual redox flow cell frames.

[0010] Furthermore, it is optionally possible to produce the individual components of the redox flow stack using additive manufacturing. This means that a second conductive material is used to form the electrodes, allowing them to be built directly within the cell frame or simultaneously with the cell frame. This simplifies the manufacturing process and enables optimal contact.

[0011] The advantage of simple manufacturing, however, comes at the cost of making the electrodes difficult to build using additive manufacturing processes. In particular, the electrically conductive plastic material is not easy to process, and the necessary lattice-like structure requires complex control and slows down the build speed. VERSION OF THE INVENTION

[0012] The object of the invention is to enable a simplified manufacturing and handling of redox flow stacks.

[0013] The problem is solved by an embodiment of a redox flow stack according to the invention as described in claim 1. A method according to the invention for producing an advantageous redox flow stack is specified in claim 4. Advantageous embodiments are the subject of the dependent claims.

[0014] The redox flow stack comprises a left and a right termination element, as well as several redox flow cells arranged between these termination elements. Each redox flow cell has a left and a right cell chamber with corresponding electrodes and cell frames, and a cell membrane that... 2024PF00388 Foreign version 4 cell compartments are separated. In addition, cell separators exist between adjacent compartments. Cell chambers present.

[0015] The innovation lies in the fact that all cell frames consist of a one-piece stack frame manufactured using additive manufacturing, with the electrodes embedded under voltage.

[0016] This allows for simplified handling and leads to improved sealing, which in turn increases the performance and service life of the redox flow stack. Furthermore, with appropriate design of the stack frame, the tie rods typically used to brace the assembly can be eliminated. DESCRIPTION OF THE INVENTION

[0017] A redox flow stack of the type is used in a redox flow battery. The other design and configuration of the redox flow battery are irrelevant in this respect. What is relevant is that the redox flow stack comprises a plurality of redox flow cells, which are arranged between end elements forming the ends on both sides.

[0018] Therefore, there is a left termination element, followed by the majority of redox flow cells, as well as a right termination element.

[0019] Each redox flow cell has a left cell chamber and a right cell chamber separated by a cell membrane. The right cell chamber is surrounded by a right cell frame, and similarly, the left cell chamber by a left cell frame. Each cell chamber contains an electrode; that is, the left cell chamber contains a left electrode, and the right cell chamber contains a right electrode.

[0020] The cell chambers of adjacent redox flow cells are each separated from each other by a cell divider. 2024PF00388 Foreign version 5. Supply bores and supply channels are provided in each cell frame for the supply and removal of the two electrolytes into and out of the cell chambers. The supply bores extend through the entire redox flow stack, with typically one supply bore for the supply and one supply bore for the removal of each electrolyte. In contrast, the supply channels in each individual cell frame connect the respective cell chamber to its corresponding supply bore.

[0022] The usual stacking of the majority of cell frames is unnecessary, since according to the invention the cell frames are manufactured as a one-piece stack frame in an additive manufacturing process.

[0023] The design of the redox flow stack reduces the effort required for handling the individual components, especially the cell frames, and also eliminates the problem of potential leaks between the individual cell frames. With sufficient stability of the stack frame, the usual tie rods for bracing the assembly can be omitted. This simplifies both the manufacturing and handling of the redox flow stack. Furthermore, the elimination of the tie rods reduces the size of the redox flow stack. Typically, the electrodes are designed in a three-dimensional grid or mesh and are slightly compressed when installed in a stacked redox flow cell to ensure reliable contact between each electrode and its corresponding current plate (first left electrode or last right electrode) or the adjacent cell divider, thus guaranteeing current flow.

[0025] According to the invention, a combination of the conventional design with a stacked structure of the redox flow cells is employed, along with the proposal to produce redox flow stacks entirely using an additive manufacturing process, wherein the electrodes in the redox flow stack are enclosed in the respective cell chambers in a compressed state. This is considered to be the case when the 2024PF00388 Foreign version 6 The thickness of the respective cell chamber corresponds to at most 0.95 times the thickness of the electrode used, whereby the thickness of the electrode is determined in the unenclosed state. [0026j The design of the end elements is initially irrelevant. In any case, it must be ensured that the adjacent cell chamber is sealed on the side of the respective end element. Furthermore, the end elements preferably ensure sufficient stability for handling and operating the redox flow stack. In addition, the necessary connections for connecting external lines to the supply bores are usually provided on the end elements.

[0027] The necessary electrical connection for operating the redox flow stack is preferably arranged at the termination elements, wherein the termination elements have an electrical connection to the respective adjacent electrode.

[0028] Advantageously, the termination elements comprise an end plate and a current plate. The end plate provides the necessary stability for terminating the redox flow stack and advantageously incorporates the connections required on the redox flow stack. The current plate, on the other hand, is designed to establish the connection from a current terminal to an adjacent electrode.

[0029] It is particularly advantageous if the left end plate of the left end element and the right end plate of the right end element are part of the one-piece stack frame.

[0030] Initially, it is irrelevant how the end plates were manufactured and how they are firmly connected to the adjacent cell frame. At the very least, a material connection must exist so that, on the one hand, the tightness of the first and last cell chambers is guaranteed, and on the other hand, no other fastening or securing of the end elements is necessary (and tie rods can be dispensed with). That is to say, although all cell frames are connected by means of a 2024PF00388 Foreign version 7 Although the cell frames are manufactured using additive manufacturing processes, this does not necessarily apply to the end plates, even though they are permanently connected to the adjacent cell frames. The advantageous design of the stack frame with integrated end plates enables the beneficial, inherently stable design of the redox flow stack and thus facilitates easy handling. Furthermore, it is particularly advantageous if the height of the electrodes, when enclosed in their respective cell chambers, is at most 85% of the thickness of the uncompressed electrodes. The stack frame can be made from various materials. Generally, plastic materials are preferred for the production of cell frames and end plates. Consideration must be given to both the necessary resistance to the electrolytes used in the redox flow stack and the required suitability for the additive manufacturing process. Therefore, materials such as polyamide, polypropylene, acrylonitrile butadiene styrene, polyetheretherketone, or polyetherimide can be used.

[0034] If the end plates or the left end plate are not manufactured in the same additive manufacturing process, it is advantageous if their material matches that of the cell frames, so that, for example, trouble-free welding is possible.

[0035] According to the invention, the stack frame is assembled using an additive manufacturing process. Accordingly, an additive manufacturing facility is required for its production. Typically, assembly takes place on a build platform, where either the build platform is movable in space or a print head for producing the respective component is movable in space. It is also logical to provide that both the build platform and the print head are movable. 2024PF00388 Foreign version 8 preferably a manufacturing device is used in which the print head can be swivelled in space on a robot arm, for example.

[0036] During the fabrication of the redox flow stack, it is still necessary to insert electrodes, cell membranes, and cell separators. The fabrication process for the redox flow stack can vary, but in every case, it requires both the production of the respective cell frames using additive manufacturing and the insertion of the elements.

[0037] Due to the need to insert the additional elements, i.e., the electrodes, cell membranes, and cell separators, it is particularly advantageous if the manufacturing equipment has an additional storage device by means of which the corresponding elements can be introduced during the additive manufacturing process, depending on the sequence of steps. This can be achieved either by ensuring that the assembly platform is sufficiently accessible or, alternatively, that the storage device is movable within the space. It is also possible to ensure that both the assembly platform and the storage device are moved simultaneously.

[0038] Advantageously, the redox flow stack is built starting from the left side, beginning with the left end plate – step LA (left side step a). In one variant, the left end plate can be manufactured directly in the additive manufacturing process. In a second variant, a left end plate manufactured by other means (e.g., injection molding) is used as the starting element.

[0039] Starting from the left end plate, the first step is to place the left power plate onto the left end plate – step LB (left side step b). The support device can be used for this, which places the power plate onto the end plate from a pre-positioned position. 2024PF00388 Foreign version 9. The following steps for manufacturing the individual redox flow cells are repeated according to the number of redox flow cells, with two preferred variants for the process being proposed. First, the left cell frame is built up in the additive manufacturing process, preferably by moving and, if necessary, pivoting the printhead – step LC (left side step c). It can be provided that the left cell frame simultaneously provides a membrane recess as a step surrounding the left cell chamber for arranging the cell membrane.

[0042] In the first variant, after the left cell frame has been assembled, a left electrode is placed into the left cell chamber provided by the left cell frame – step LD (left side, step d). After the left electrode has been placed, a cell membrane is placed onto the previously inserted left electrode – step LE (left side, step e). Alternatively, it may be possible to place a left electrode and the cell membrane simultaneously.

[0043] In the first variant, after the cell membrane has been positioned, the stack frame is further assembled by manufacturing the right cell frame in the additive manufacturing process – step RC (right side step c). It can also be provided that the right cell frame has a recess for the separating element, forming a step surrounding the right cell chamber for the placement of the cell separating membrane. Analogous to the left side, the right electrode can now be inserted into the right cell chamber – step RD (right side step d) – and the cell separator can be placed on the right electrode – step RE (right side step e). It may be possible to place the right electrode and the subsequent cell separator simultaneously.

[0045] In the second variant, it is always necessary to provide a membrane recess in the left cell frame before proceeding with the further assembly of the stack frame immediately after the assembly of the left cell frame by producing the 2024PF00388 Foreign version The right cell frame is processed in the additive manufacturing process – step RC' (right side alternative step c'). It can also be provided that the right cell frame has a recess for the separating element, forming a step surrounding the right cell chamber for the placement of the cell separation membrane.

[0046] In the second variant, after the right cell frame has been assembled, a left electrode is placed into the left cell chamber provided by the left cell frame – step LD (left side, step d). After the left electrode has been placed, a cell membrane is placed onto the previously inserted left electrode – step LE (left side, step e). Alternatively, it may be possible to place a left electrode and the cell membrane simultaneously.

[0047] Analogous to the left side, the right electrode can now be inserted into the right cell chamber – step RD (right side step d) – and the cell separator placed onto the right electrode – step RE (right side step e). It may be possible to place the right electrode and the subsequent cell separator simultaneously. Furthermore, regardless of the first or second variant, it is possible to form a unit with a left electrode, a cell membrane and a right electrode, which are simultaneously inserted into the right cell frame.

[0049] In the second variant, it is also possible to insert the elements of a redox flow cell, i.e. a left electrode, a cell membrane and a right electrode, and the associated cell separator element, simultaneously into the prepared right and left cell frames.

[0050] If the number of redox flow cells in the redox flow stack is "n", then steps LA to LE are repeated n-1 times. The assembly of the redox flow cells ends with the last redox flow cell "n" and the placement of the last right electrode – step RD. 2024PF00388 Foreign version 11 After the formation of the redox flow cells, the right current plate is placed on the last right electrode - step RB. Finally, the right end plate is firmly connected to the last right cell frame. This can be done, for example, by welding.

[0053] Depending on the material chosen for the stack frame and the end plate, the end plate can also be attached to the stack frame by adhesive bonding. Preferably, at least the right end plate is also manufactured using additive manufacturing, which simplifies the process and avoids the risk of leakage. In the redox flow stack according to the invention, the electrodes are clamped in the cell chambers with slight compression. This is taken into account in the additive manufacturing process by using a hold-down device to compress the already inserted electrodes, cell membranes, and cell dividers during the assembly of the left and right cell frames, respectively. This allows for the unimpeded assembly of subsequent cell frames, including the surrounding cell membrane and cell divider.

[0056] It is considered necessary that, using the clamp, the uppermost electrode placed last is compressed to a height of no more than 90% of its original height before use in the redox flow stack. It is particularly advantageous if the compressed height corresponds to no more than 0.8 times the thickness of the electrode before use. The clamp and its arrangement on the last electrode can be implemented in various ways. In a first, particularly advantageous variant, the clamp is formed by a weight plate. For example, a metal plate can be used for this purpose, which is... 2024PF00388 Foreign version 12 of the appropriate size and mass ensures the necessary compression of at least the last electrode placed. Advantageously, the metal plate is placed on the device and, after the respective manufacturing process, removed again to form the corresponding cell frame for placing further elements of the redox flow stack.

[0058] In a second advantageous embodiment, the hold-down device is simultaneously formed by the storage device. For this purpose, it can be provided, for example, that the storage device has a corresponding flat plate at its end when no elements are to be placed on it. The storage device then generates the necessary force to compress the last electrode.

[0059] In particular, with the second variant, it must be taken into account that the advantageous additive manufacturing equipment is set up in such a way and the print head is so durable and, if necessary, pivotable that the complete production of the cell frames is possible, taking into account the hold-down device, i.e. the weight plate or the storage device. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] FIG 1 schematically shows the construction of an exemplary redox flow stack 01 with several redox flow cells 11 using a one-piece stack frame 02.

[0061] Figures 2 to 11 below illustrate the process for producing the redox flow stack from Fig. 1.

[0062] FIG 2 sketches - after steps LA and LB - in section a left end element comprising a left end plate 03 and a left current plate 05.

[0063] FIG 3 sketches - after steps LA and LB - in top view the left end element from Fig. 2 comprising the left end plate 03 and the left stream plate 05. 2024PF00388 Foreign version 13

[0064] FIG 4 sketches - after step LC - the partially manufactured part in section. Stack frame 02.1 L continues to include a first left cell frame 15.1.

[0065] FIG 5 shows - after step LC - a top view of the partially completed stack frame 02.1 L.

[0066] FIG 6 sketches - after steps LD and LE - in section the partially completed stack frame 02.1 L from Fig. 4 with the first left electrode 17.1 and the first cell membrane 12.1 in place.

[0067] FIG 7 shows – after steps LD and LE – a top view of the partially completed stack frame 02.1 L from Fig. 5 with the first cell membrane 12.1

[0068] FIG 8 sketches - after step RC - in section the partially completed stack frame 02.1 R further encompassing a first right cell frame 16.1.

[0069] FIG 9 shows - after step RC - a top view of the partially completed stack frame 02.1 R.

[0070] FIG 10 sketches - after steps RD and RE - in section the partially completed stack frame 02.1 R from Fig. 4 with support of the first right electrode 18.1 and the cell separating element 19.1-2 between first and second redox flow cell 11.1 , 11.2.

[0071] FIG 11 shows - after steps RD and RE - a top view of the partially completed stack frame 02.1 R from Fig. 9 with the cell separating element 19.1-2.

[0072] Figure 1 shows a cross-sectional sketch of an exemplary embodiment of a redox flow stack 01 according to the invention. This example comprises three redox flow cells 11 (i.e., 11.1, 11.2, 11.3). Each of these 11 comprises a left cell frame 15 (i.e., 15.1, 15.2, 15.3), which surrounds a left cell chamber 13 (i.e., 13.1, 13.3, 13.3) in which a left electrode 17 (i.e., 17.1, 17.2, 17.3) is arranged, and a right cell frame 16 (i.e., 16.1, 16.2, 16.3), which 2024PF00388 Foreign version 14 16 surrounds a right cell chamber 14 (i.e., 14.1, 14.2, 14.3) in which a right electrode 18 (i.e., 18.1, 18.2, 18.3) is arranged. The two cell chambers 13, 14 are each separated from each other by a cell membrane 12 (i.e., 12.1, 12.2, 12.3). The cell chambers (13) of adjacent redox flow cells 11 are each separated from each other by a cell divider 19 (i.e., 19.1-2, 19.2-3).

[0073] Supply channels 23 and 24 (i.e., 23a.1, 23b.1, ..., 24a.3, 24b.3) for the inflow and outflow of electrolytes are connected to cell chambers 13 and 14, respectively. Supply channels 23 and 24 run within the respective cell frames 15 and 16.

[0074] On the left side, i.e., in the lower part of the diagram, a left current plate 05 forms the beginning before the first redox flow cell 11.1. The right side, i.e., in the upper part of the diagram, is formed by a right current plate 06, which forms the end after the last redox flow cell 11.3.

[0075] Essential for the inventive embodiment of the redox flow stack 01 is the one-piece stack frame 02 produced in an additive manufacturing process. In this embodiment, the stack frame 02 comprises, in addition to the cell frames 15, 16, the left end plate 03 and the right end plate 04.

[0076] Figures 2-11 below illustrate a possible production sequence for the redox flow stack 01. Each figure shows a cross-section through the respective construction phase, followed by a top view.

[0077] The illustration of the required additive manufacturing equipment and the necessary storage device is omitted.

[0078] The assembly of the redox flow stack 01 begins with the provision of the left end plate 03 - step LA, which 03 is produced, for example, by injection molding. 2024PF00388 Foreign version 15 was manufactured. The left power plate 05 is placed on the left end plate 03 - step LB, see Figure 2.

[0079] Figure 3 shows a top view of the left end plate 03 with the left flow plate 05 placed on it. This view also sketches the section for the representation in Figure 2. The arrangement of supply bores 21, 22 is also visible, with a left supply bore 21a for the inlet to the left cell chambers 13, a left supply bore 21b for the outlet from the left cell chambers 13, a right supply bore 22a for the inlet to the right cell chamber 14, and a right supply bore 22b for the outlet from the right cell chambers 14.

[0080] The construction of the redox flow stack 01 continues with the production of the first left cell frame 15.1 using the additive manufacturing process - step LC, see Figure 4, whereby the partial stack frame 02.1 L is formed.

[0081] Figure 5 shows a top view of Figure 4.

[0082] The structure of the partial stack frame 02.1 L, comprising the left end plate 03 and the first left cell frame 15.1, is visible. The left current plate 05 is enclosed within this frame. The first left cell frame 15.1 surrounds the first left cell chamber 13.1, with two supply channels (shown here as the left supply channel 23b.1, draining from the first left cell chamber 13.1) within the left cell frame 15.1 connecting to the left supply bores 21. At the upper end (as shown), a step surrounds the first left cell chamber 13.1 to form a first membrane recess 20.1. 2024PF00388 Foreign version 16

[0084] The assembly of the redox flow stack 01 continues with the placement of a first right electrode 17.1 - step LD - and the placement of a first cell membrane - step LE, see Figure 6. Figure 7 shows a top view of Figure 6. It can be seen that the first left electrode 17.1 has a greater height than the height of the existing first left cell chamber 13.1. Therefore, in its relaxed state, the first left electrode 17.1 extends beyond the first left cell chamber 13.1. Accordingly, the first cell membrane 12.1 is also located above the intended membrane recess 20.1. The assembly of the redox flow stack 01 continues with the production of the first right cell frame 16.1 using the additive manufacturing process – step RC, see Figure 8, whereby the partial stack frame 02.1 R is formed. Figure 9 shows a top view of Figure 8. [OOEö] The structure of the partial stack frame 02.1 R, comprising the left end plate 03, the first left cell frame 15.1, and the first right cell frame 16.1, can be seen. Included within this are the left current plate 05, the first left electrode 17.1, and the first cell membrane 12.1. The first right cell frame 16.1 surrounds the first right cell chamber 14.1, with two supply channels (the right supply channel 24a.1 as an inlet to the first right cell chamber 14.1 and the right supply channel 24b.1 as an outlet from the first right cell chamber 14.1) connected to the supply bores 21 within the right cell frame 16.1. At the upper end (as shown), a step surrounding the first right cell chamber 14.1 forms a first separating element recess 30.1-2. 2024PF00388 Foreign version 17 [0091 J During the construction of the first right cell frame 16.1 - step RC - it is provided that a retainer is arranged on the first cell membrane 12.1, which causes a corresponding compression of the first left electrode 12.1. The assembly of the redox flow stack 01 continues with the placement of a first left electrode 18.1 - step RD - and the placement of a cell separation element 19.1-2 - step DE - separating the first right cell chamber 14.1 from the second left cell chamber 13.2, see Figure 10. Figure 11 shows a top view of Figure 6. It can be seen that, analogously, the first right electrode 18.1 has a greater height than the height of the existing first right cell chamber 14.1. Therefore, in its relaxed state, the first right electrode 18.1 extends beyond the first right cell chamber 14.1. Accordingly, the cell separator 19.1-2 is also located above the intended separator recess 30.1-2. The formation of the subsequent redox flow cells 11.2, 11.3 is not shown but proceeds analogously to the construction of the first redox flow cell 11.1.

[0096] Before the redox flow stack 01 is completed, the right current plate 06 must be positioned after the last right electrode 18.3 is placed, instead of a cell separator – step RB. To complete the redox flow stack 01, the right end plate 04 is then manufactured – step RA. Since the right end plate 04 cannot be fully manufactured in the presence of the retainer, it is advantageous that, after the right end plate 04 has been sufficiently assembled and the position of the right current plate 06 is secured, the retainer is removed and the right end plate 04 can be completed by compressing the last right electrode 18.3. 2024PF00388 Foreign version 18

[0098] Also not shown are the advantageous connections on the end plates 03, 04, which can optionally be incorporated directly or mounted in the end plates 03, 04. REFERENCE MARK LIST 01 Redox Flow Stack 02 Stack frames 02.1 L Construction phase Stack frame with first left cell frame 02.1 R Construction phase Stack frame with first right cell frame 03 left end plate 04 right end plate 05 left power plate 06 right power plate 11 Redox flow cell 11.1 First redox flow cell 11.2 Second redox flow cell 12 Cell membrane 12.1 first cell membrane 12.3 third cell membrane 13 left cell chamber 13.1 first left cell chamber 13.1 second left cell chamber 13.3 third left cell chamber 14 right cell chamber 14.1 first right cell chamber 14.2 second right cell chamber 15 left cell frame 15.1 first left cell frame 15.2 second left cell frame 15.3 third left cell frame 16 right cell frame 16.1 first right cell frame 16.2 second right cell frame 16.3 third right cell frame 17 left electrode 17.1 first left electrode 17.3 third left electrode 18 right electrode 18.1 first right electrode 18.3 third right electrode 2024PF00388 Foreign version 19 19 Cell separator 19.1-2 Cell separator between first and second redox flow cell 19.2-3 Cell separator between second and third redox flow cell 20 Membrane recess 20.1 first membrane recess 21 left supply borehole 21 a left supply bore inlet 21 b left supply borehole drain 22 right supply borehole 22a right supply borehole inlet 22b right supply borehole drain 23 left supply channel 23a.1 Left supply channel, inlet to first cell chamber 23b.1 Left supply channel, outflow of first cell chamber 24 right supply channel 24a.1 right supply channel inlet first cell chamber 24b.1 Right supply channel, outflow of first cell chamber 24a.3 right supply channel inlet third cell chamber 24b.3 Right supply channel, third cell chamber 30 Separating element recess 30.1 -2 T Separation element recess between first and second redox flow cell

Claims

2024PF00388 Foreign version 20 Claims What is claimed:

1. Redox flow stack (01) for use in a redox flow battery comprising - a left-hand closing element, and - a right-hand closing element and - several redox flow cells (11) arranged between the terminal elements, each (11) having a left cell chamber (13) and a left electrode (17) arranged therein and a surrounding left cell frame (15) and a right cell chamber (14) and a right electrode (18) arranged therein and a surrounding right cell frame (16) and a cell membrane (12) separating the cell chambers (13, 14), and - several cell separating elements (19), which (19) are each arranged between cell chambers (13, 14) of adjacent redox flow cells (11); wherein the cell frames (15, 16) have supply bores (21, 22) for supplying and removing electrolytes and supply channels (23, 24) for connecting the cell chambers (13, 14) to the associated supply bores (21, 22), wherein all cell frames (15, 16) consist of a one-piece stack frame (02) produced in an additive manufacturing process, characterized in that the electrodes (17, 18) are compressed to a height of at most 95% relative to a thickness in a relaxed state.

2. Redox flow stack (01) according to claim 1, wherein the termination elements each comprise an outer end plate (03, 04) and a current plate (05, 06) arranged towards the adjacent redox flow cell (11), wherein the end plates (03, 04) are part of the one-piece stack frame (02). 2024PF00388 Foreign version 21 3. Redox flow stack (01) according to claim 1 or 2, wherein the electrodes (17, 18) are compressed to a height of at most 85% relative to a strength in a relaxed state.

4. Method for producing a redox flow stack (01) according to one of the preceding claims in an additive manufacturing process, comprising the steps: LA - Assembly or provision of the left end plate (03); LB - Support of the left current plate (05); and repeating: LC - Construction of a left cell frame (15); RC' - alternative to step RC Construction of a right cell frame (16); LD - Placement of a left electrode (17); LE - layer of a cell membrane (12); RC - alternative to step RC' Construction of a right cell frame (16); RD - Placement of a right electrode (18); RE - Placement of a cell separator element (19); and finally, after a last step, RD; RB - right power plate (06); RA - Assembly or provision of the right end plate (04), wherein during the assembly of the left cell frame (15) and during the assembly of the right cell frame (16) the already inserted electrodes (17, 18) and cell membranes (12) and cell separating elements (19) and the last electrode (17, 18) in each case are compressed to a maximum of 90% of a height in the relaxed state by a hold-down device. 2024PF00388 Foreign version 22 5. The method of claim 4, wherein the left electrode (17) and the cell membrane (12) are applied simultaneously; and / or wherein the right electrode (18) and the cell separator element (19) are applied simultaneously; and / or wherein the left electrode (17) and the cell membrane (12) and the right electrode (18) are applied simultaneously; and / or the left electrode (17) and the cell membrane (12) and the right electrode (18) and the cell separating element (19) are applied simultaneously.

6. Method according to claim 4 or 5, wherein the last electrode (17, 18) is compressed to a maximum of 80% of its height in the relaxed state.

7. A method according to any one of claims 4 to 6, wherein an additive manufacturing device is used, comprising a build-up platform and at least one printhead movable in space and a depositing device, wherein the build-up or depositing of the left end plate (03) on the The assembly platform is constructed, wherein the cell frames (15, 16) are constructed using the print head, and the electrodes (17, 18) and the cell membrane (12) and the cell separating element (19) are placed by the depositing device when the assembly platform is moved and / or by moving the depositing device.

8. Method according to one of claims 4 to 7, wherein the hold-down is formed by a weight plate, in particular a metal plate, which in particular has the necessary mass for compressing the electrodes (17, 18). 2024PF00388 Foreign version 23 9. Method according to claim 8, wherein the hold-down device is placed on the storage device and subsequently removed from the assembly of the respective cell frame (15, 16).

10. Method according to any one of claims 4 to 7, wherein the storage device simultaneously forms the hold-down device.

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