Method and process arrangement for manufacturing a cell stack for a battery cell

Abstract

The invention relates to a method for producing a cell stack for a battery cell, comprising a Z-folding process, in which a separator web (1) is folded in a folding station (43) to form separator segments (3) stacked one above the other in a stacking direction, which segments merge into one another at folding edges (5), with electrode sheets (A, K) being arranged between the separator segments (3). According to the invention, before carrying out the Z-folding process, an application process takes place, in which the still unfolded separator web (1) is guided through an application station (11) in which the electrode sheets (A, K) are fixedly adhered to the separator web (1), such that the electrode sheets (A, K) are securely positioned on the separator web (1) in the Z-folding process.

Description

[0001] The invention relates to a method and a process arrangement for producing a cell stack for a battery cell according to the preamble of claim 1 and according to the preamble of claim 8.

[0002] In a process for manufacturing a cell stack for a battery cell, a Z-folding process is used. In a stacking station, a separator web is folded into separator segments stacked one on top of the other in a stacking direction. The separator segments merge into one another at the folded edges, forming a single piece of material. Electrode sheets are located between each of the stacked separator segments.

[0003] The procedure gives rise to the following problems: The first issue concerns the comparatively long process time of the Z-folding process compared to the state of the art. The Z-folding process is used to enable rapid stacking. However, there are several problems associated with this method. In Z-folding, the separator is folded into a Z shape, with the anode and cathode electrodes inserted between them. During insertion, the robot must grasp the anode or cathode and place it on the folded separator. The robot's removal of the electrode and its precise placement take time. This time increases the cycle time for assembly. This increases costs and space requirements. The robot's kinematics also require frequent maintenance and cannot be accelerated beyond a certain limit due to inertia.

[0004] The second problem concerns the inaccuracy in the placement of the electrodes in the Z-stack, which is a problem with the current technology. The robot's placement of the electrodes is monitored with a camera to check their positioning accuracy. Since stacking accuracy must be very high, it is important that the camera vision system correctly checks the position of the electrode stacks. The image processing system must check the position of the electrode stacks and transmit a signal to the robot so that it can adjust the stack position. This entire process takes time. If there is insufficient time, the stacking tolerance will not be met. For this reason, additional X-ray tests can be performed to verify the stack position.This means that the current cell assembly process requires two vision systems, one with a camera and one with X-rays, to ensure that stacks that are out of tolerance do not advance to the next cell packaging process. During the Z-folding process, the stacking table is slightly tilted to facilitate electrode placement. Due to the tilt of the stacking table, the electrode may occasionally slide downward. This means that even if the robot has correctly placed the electrode on the separator, it may still slide downward, resulting in a loss of accuracy.

[0005] The third problem concerns the fact that during the stacking process, the Z-stack forming in the stacking station is compressed to a certain package density by a hold-down device, which can lead to damage to the electrodes. Once the electrode is placed on the separator during the Z-stacking process, it is usually held in place with a clamp or hold-down device. This clamp is released, and then a new separator is placed over the already placed electrode. The same clamp is reapplied and now holds the new separator and the already formed stack together. The clamp is released again when the new electrode is placed on the last placed separator. After the electrode has been placed, the clamp is reapplied. Two problems arise during this process. The clamp must be constantly moved in and out of clamping engagement.The clamp movement required for this is generated by a spring whose stiffness decreases over time. Furthermore, the surface of the electrode and separator is constantly in contact with the clamp. This can lead to surface defects on the electrode and separator surfaces.

[0006] A fourth problem concerns the frequent interruptions of the Z-folding process in the current state of the art. Often, the electrode sheets to be stacked are not properly held by the robot's vacuum gripper and fall down. In this case, the Z-folding station must be stopped to remove the dropped electrode sheets. In some cases, the entire stack must be discarded. The overall equipment efficiency of a conventional stacking machine is a maximum of 80%. This low efficiency is primarily due to the performance of the robot arm at high process speeds. Furthermore, surface defects can occur when the vacuum gripper holds the electrode sheets.

[0007] EP 4 152 469 A1 discloses a generic method for manufacturing a cell stack for a battery cell. CN 1 12 216 858 A, EP 3 890 082 A1, and DE 10 2018 200 958 A1 disclose further methods for manufacturing such a cell stack. EP 2 892 102 B1 discloses a method for manufacturing an electrode assembly. The method comprises the following process step: forming a unit structure comprising a stacked structure formed by sequentially stacking a first electrode, a first separator, a second electrode, and a second separator. Alternatively, the unit structure may comprise a stacked structure formed by repeatedly forming the stacked structure.

[0008] The object of the invention is to provide a method and a process arrangement for producing a cell stack for a battery cell, which can be produced with greater process reliability compared to the prior art, in particular with increased storage accuracy of the electrode sheets compared to the prior art.

[0009] The object is achieved by the features of claim 1 or 8. Preferred developments of the invention are disclosed in the subclaims.

[0010] The invention is based on a method for producing a cell stack for a battery cell, in which a Z-folding process is carried out. In the Z-folding process, a separator web is folded into separator segments in a stacking station, which are stacked one on top of the other in a stacking direction. The separator segments merge into one another at folded edges, making them of the same material and integrally. Electrode sheets are arranged between the separator segments. According to the invention, an application process is carried out before the Z-folding process to increase the positional accuracy of the electrode sheets. During the application process, the still unfolded separator web is guided through an application station, in which the electrode sheets are fixedly adhered to the separator web. In this way, the electrode sheets are already securely positioned on the separator web in the Z-folding process, without there being any risk of the electrode sheets shifting during the Z-folding process.In the application step, all anodes are preferably applied on one side of the separator web and all cathodes on the other side of the separator web.

[0011] According to the invention, the anodes and cathodes are attached to the separator before it undergoes a Z-fold. There are various ways to attach the electrodes to the separator: In a first option, the electrode sheets are bonded to the separator using PVDF or another acrylic-based adhesive. The adhesive is applied to both sides of the separator using transfer rollers. Alternatively, the electrodes can be applied using electrostatic force. In this case, the separator and electrode have different electrostatic charges, which lead to electrostatic forces of attraction. In another variant, the electrodes are attached to the separator using a clamping unit. The clamping jaws of the clamping unit are only released when the Z-stack of electrode and separator is correctly positioned in the stacking magazine.

[0012] A hold-down device can be provided if necessary to compress the Z-stack forming in the stacking station. The hold-down device preferably only contacts the separator surface and not the electrode surface. This prevents damage to the electrode surface.

[0013] According to the invention, no robots are required for stack formation, so there are no suction marks on the electrode, and no positioning of the electrode on the separator is required during the stacking process. The separator attached to the electrode can be fed directly to the stacking station in a continuous process. Alternatively, it is also possible to first wind the separator web loaded with the electrodes onto a take-up roll and start the Z-stacking process at a later stage.

[0014] Since the electrodes are attached to the separator prior to Z-folding, the invention eliminates the time required to adjust the electrodes on the separator during the conventional Z-stacking process, while simultaneously increasing placement accuracy.

[0015] In the process arrangement according to the invention, the separator is unwound as an endless web (hereinafter also referred to as the separator web) from a supply reel. With the aid of dancer rolls, the separator web can be designed with a lag length to achieve a balance between the continuous separator web supply and the discontinuous loading of the separator web with the electrodes. The separator is held in a stationary state during the electrode connection.

[0016] The separator is passed through two coating rollers in the process setup. Here, the adhesive is applied to both sides of the separator. One coating roller applies the adhesive to one side of the separator, where the anode is to be attached, and the other coating roller applies the adhesive coating to the other side of the separator, where the cathode is to be attached.

[0017] The coating rollers receive the adhesive from transfer rollers. The coating rollers, for example, have a sponge-like structure that is the same size as the electrode. The sponge receives the adhesive from the transfer rollers. The transfer rollers are wetted with adhesive either by dipping or spraying. The adhesive is not applied evenly across the separator web, viewed in the conveying direction, but only in the area where the electrode is to be attached. Non-aqueous adhesives such as PVDF, aluminum oxide in an acrylic-based adhesive binder, insulating polymers such as aramid or silicone can be used as non-aqueous adhesives. Polymer electrolyte can also be used as an adhesive. Furthermore, a PVDF gel in an electrolyte can be used as an adhesive. The counterpressure roller, or the support roller for adhesive attachment, only touches the electrode when adhesive needs to be applied.It is adjustable in vertical motion. This ensures that previously applied adhesive coatings are not affected by contact with the support roller.

[0018] The electrodes can be stored in two different magazines. An active main magazine guides the electrodes toward the separator track; the respective electrode is pushed from the magazine to the separator and attached to the separator, which rests against the support roller. Once the active main magazine is empty, a buffer magazine or spare magazine is used. While the buffer magazine is in use, the active main magazine is refilled with electrodes. The electrodes to be applied to the separator track are already pre-cut.

[0019] The electrodes can be brought into contact with the separator track in various ways, such as compressed air, a pneumatic cylinder, or a mechanical lever. Once the electrodes are attached to the separator, the separator is moved again using a traction device, thus applying electrodes to a new separator section.

[0020] The separator, loaded with electrodes, can be fed directly to the Z-folding process or stored temporarily in the form of a coil. This coil can then be used to produce stacks similar to the Z-folding process. The only difference is that the electrode is already attached to the separator, and with the Z-folding process, no electrode needs to be inserted. A continuous Z-folding process is preferable because the electrodes are subject to less bending compared to winding onto a take-up roll.

[0021] Another way to attach the electrodes to the separator is through electrostatic attraction. For this purpose, the separator's surface should be positively charged. To achieve a positive charge, the separator is rubbed against a hard rubber roller, for example. The friction (or rolling) creates a positive charge on the top and bottom surfaces of the separator. Since both rubber rollers are grounded, a constant negative charge can build up on the rollers, which in turn creates a positive charge on the top and bottom surfaces of the separator. The positive charge is primarily deposited on the ceramic and PVDF coatings of the separator's surface and remains positive longer because the separator is non-conductive.

[0022] Finally, a negatively charged Teflon strip can be applied to the cathode and anode cartridges. This positively charges the cathodes and anodes. Electrostatic attraction holds the electrodes firmly to the separator. The advantage of electrostatic charging is that it can be quickly applied to both the separator and the electrodes. In this case, no adhesive is required.

[0023] It is also possible to provide a protective Teflon layer on the electrodes, which is positively charged. This protective layer can be easily peeled off once the electrostatic charge has been removed. This is done shortly before Z-folding. It is preferred if the electrodes are negatively charged without this protective layer. There are several ways to negatively charge the electrode. For example, the anode and cathode magazines can be charged with a negative charge, so that the electrode stacks are negatively charged. Alternatively, an additional Teflon protective film can be applied to the electrodes after they have been attached to the separator. The Teflon film is inherently negatively charged; in this way, the electrode, although it has no charge, is held firmly between the Teflon film and the separator.

[0024] Here, it's also possible to combine adhesive and electrostatics to hold the electrode in place. The electrostatic charge gradually decreases during the Z-folding process as the separator and electrode come into contact with the conductive stacking magazine and the conductive layer.

[0025] According to the invention, a hold-down device can be assigned to the stacking station. This hold-down device preferably only comes into contact with the separator surface, but not with the electrodes. Normally, the Z-stack formed during the Z-folding process must be compressed with the help of the hold-down device in order to achieve a predefined package density in the Z-stack. The hold-down device, located outside the stacking magazine, moves toward the separator web and comes into contact with it. The hold-down device then moves out of the stacking magazine. The hold-down device only comes into contact with one side of the separator, which is opposite the folding roller where the separator is bent for the Z-fold.

[0026] When moving towards the separator, the hold-down device is out of contact with the separator. Only when moving downwards does the hold-down device come into contact with the separator, so that there is no relative sliding movement between the separator and the hold-down device, but only pressure. This reduces surface defects in the separator. Because the electrode always remains out of contact with the hold-down device, the surface of the electrode is not damaged. Even during a reversing movement, the hold-down device initially moves slightly upwards vertically, whereby it comes out of contact with the separator (which it had previously pushed down). The hold-down device then moves horizontally back to its starting position. This means that there is no sliding contact between the separator and the hold-down device, even during the reversing movement of the hold-down device.

[0027] Once the stack is complete, the separator web is cut to length. An adhesive tape is also applied to the stack. While the adhesive tape is being applied, the stack is compressed using a pressure force to create a stable stack. During the taping process, the dancer roller moves downward, creating a lag length for the next Z-stack.

[0028] According to the invention, the process arrangement comprises a clamping unit with a number of pairs of clamping jaws arranged one behind the other. These pairs are part of a conveyor system. In principle, the separator and the electrodes can be held from both the conductor lug side and the opposite side. Two pairs of clamping jaws can convey the layered assembly consisting of separator web and electrode to the Z-folding station.

[0029] The clamps hold the electrode and separator in a Z-fold. Just before the separator is placed in the stacking magazine in a Z-fold, the clamping jaws holding the electrode and separator on the side opposite the conductor tabs are released. The electrode and separator are moved further down the stacking table or stacking magazine. The separator and coil are then positioned from the sides by the stacking table. Only then are the clamping jaws on the separator and the electrode on the conductor tab side released. This ensures that the separator and electrode are always precisely aligned. This option requires no electrostatic force or adhesive.

[0030] The hold-down device presses the separator (shortly after the clamping jaws are released) into the stacking magazine. The side plates of the stacking magazine secure the separator and the electrode terminals.

[0031] If adhesive or electrostatic force is used in addition, these forces may be weaker than in the two previous embodiments. In this case, it is possible for both pairs of jaws to be released simultaneously. However, clamps without adhesive and electrostatic force are preferable, in which the two pairs of jaws are released at different process times.

[0032] The differences between the invention and the prior art are highlighted again below: The electrodes (cathode and anode) are attached to the top and bottom of the separator before it is Z-folded. The electrodes can be attached using various methods or a combination of such methods. The electrodes can be attached by gluing, with the adhesives being binders such as PVDF or many other insulating adhesives already discussed. The method of bonding has already been explained in detail. The continuous movement of the separator is stopped shortly before bonding, with the dancer rollers holding the separator web taut. The adhesive is applied by the coating or applicator roller, which receives the adhesive from the transfer roller. The transfer roller receives the adhesive either by spraying or dipping.The adhesive is applied only to the area of the separator that will come into contact with the electrode. This is done using a sponge-like material attached to the coating roller. The separator with the bonded electrodes can go directly into the Z-folding process, or it can be rolled into a coil for storage, and the Z-folding can then be performed at a later stage.

[0033] Another method of electrode attachment uses electrostatic force. Here, the separator is electrostatically charged either positively or negatively. For example, the separator can be positively charged. The positive charge is generated by a roller that draws electrons from the separator's surface and injects a positive electrostatic charge into the separator. Alternatively, the electrodes are oppositely charged, either by a charging magazine containing the electrode sheets or by an electrostatically charged Teflon layer on the separator. This Teflon layer is removed shortly before the Z-fold. It is better to combine adhesive bonds and electrostatic charging to achieve strong adhesion between the separator and the electrode. This means that the Teflon layer usually holds the electrode to the separator through electrostatic charging.Only when this charge is removed by neutralizing the charge is the weak adhesive force sufficient to hold the electrode to the separator. It is also possible to use Teflon as an adhesive layer on the electrode surface (without touching the separator) and then charge this adhesive layer with an electrostatic charge. The electrostatic charge only needs to be neutralized if the Teflon layer covering the electrode is to be removed. If the Teflon adhesive layer is on the electrode surface, the electrostatic charge does not need to be neutralized. This electrostatic charge is neutralized over time or upon contact with the conductive stacking table or stacking magazine. The electrostatic force helps maintain strong adhesion between the electrode and separator, even when the coil is formed and later the Z-fold is performed from the coil.

[0034] Another option for attaching the electrodes to the separator track is to hold the electrode to the separator surface using clamps. These clamps move along with the separator and are removed shortly before the Z-fold. In this case, too, it would be helpful to have a weak adhesive bond or static charge on the electrode to hold the electrode in place after the clamps are removed. In most cases, the clamps hold the electrode to the separator one at a time; the clamps only need to be removed shortly before the Z-fold begins.

[0035] With the inventive solution of holding the electrode to the separator using clamps during the Z-folding process, the separator web equipped with the electrodes cannot be stored as a coil. In this case, the separator web equipped with the electrodes must be fed into the Z-folding process in a continuous process.

[0036] During the Z-folding process, the hold-down device is in contact with the separator located at the top of the stack until the next separator arrives. Unlike in the prior art, the hold-down device is not in contact with the electrode surface. This means that each separator layer required between two electrode layers (which are attached to the previous and next separator layers) can be brought into contact with the hold-down device to compress the forming Z-stack.

[0037] According to the invention, no camera system is required to determine the accuracy of electrode placement. The accuracy of electrode placement is achieved when attaching the electrode to the separator. A significantly higher production rate of parts per minute is possible compared to the prior art. No robot is required to transfer the electrode sheets to the separator, as is the case with the prior art. The electrode is already attached to the separator before it enters the Z-fold stacker. This further reduces stacking time and increases accuracy. Tilting of the stacking table is not required. The stacking table is stationary. Therefore, the Z-folding can be performed on a stacking table, and once it is finished, this table can proceed to the taping process.

[0038] The advantages of the invention are summarized below: This results in a short cycle time for stacking by Z-folding, meaning only a few stacking operations are required and the machine requires less space. Electrode surface defects resulting from the hold-down device can be avoided because the hold-down device does not touch the surface of the electrode coating. When an insulating adhesive is used, this acts like an insulating layer and increases the insulation resistance between the electrode and separator. When PVDF is used as the adhesive, the cathode conducts better. An insulating coating is preferred because this coating would prevent short circuits caused by accidental contact between the cathode and anode. When electrostatically charged, the electrodes are held firmly to the separator without the addition of inactive material.It is possible to use adhesives with a lower boiling point than 70°C, allowing them to evaporate during the curing process. It is also possible to use adhesives that dissolve in the electrolyte during electrolyte injection. In this case, the weight of the inactive component is not increased. The stacking table does not tilt. Furthermore, high accuracy in electrode placement is achieved, as the electrode does not slip on the tilted stacking table. Z-folding also eliminates the need for a costly camera. The separator can also be more firmly attached to the electrode, reducing the gaps between the cathode and anode. This extends the battery's service life.

[0039] Comparative examples not covered by the invention and an embodiment of the invention are described below with reference to the attached figures.

[0040] They show: Fig. 1 to 7 are different views illustrating a process arrangement and a method for manufacturing a cell stack.

[0041] In the Fig. Figure 1 shows a finished cell stack in which a separator sheet 1 is folded in a Z-fold to form separator segments 3 that merge into one another at fold edges 5. Between the separator segments 5, anode sheets A and cathode sheets K are arranged alternately in the stacking direction.

[0042] The following is based on the Fig. 2 and Fig. 3 describes a process arrangement according to a comparative example not covered by the invention, with which the Fig. 1 shown cell stack can be produced. The process arrangement comprises, viewed in a conveying direction FR, a unwinding roller 7, a compensating unit 9, an application station 13, an application station 11, a pulling roller arrangement 15 and a take-up roller 17 in series. From the motor-driven unwinding roller 7, the separator web 1 is continuously fed to the application station 13. The compensating device 9 arranged between the unwinding roller 7 and the application station 13 has a dancer roller arrangement 19, the operation of which is described later. The application station 13 is in the Fig. 2 is equipped with two successively arranged roller pairs, through whose roller gaps the separator web 1 is guided. Each of the roller pairs consists of an adhesive application roller 25 and a cooperating counterpressure roller 27. The application roller 25 has an application section 29 that is larger in diameter than the remaining roller diameter. With the application roller 25 rotating and the separator web advancing synchronously in the conveying direction FR, spaced-apart adhesive dots 31 can be placed on the separator web 1 with the aid of the rotating application roller.

[0043] As from the Fig. As can be seen further in Figure 2, the application rollers 25 of the two roller pairs are arranged on opposite sides of the separator web so that the adhesive dots 31 can be formed on the opposite sides of the separator web. The large-diameter application section 29 of the respective application roller 25 is in the Fig. 1 can be brought into contact with a transfer roller 33, which transfers the adhesive to the application section 29 of the application roller 25. The Fig. 2 transfer roller 33 shown below is sprayed with adhesive by means of spray nozzles 35, while the Fig. 2 upper transfer roller 33 is immersed in an adhesive bath.

[0044] Further along the separator web 1 in the conveying direction FR, there are two anode magazines 35, 37 arranged on the underside of the separator web 1, each with a counterpressure roller 36 assigned to the opposite side of the separator web. In the same way, two cathode magazines 39, 41 follow on the upper side of the separator web, each with a counterpressure roller 36 assigned to the opposite side of the separator web. The electrode magazines 35, 37, 39, 41 are components of the application station 11, in which the electrode sheets A, K are brought into adhesive connection with the separator web 1 at the adhesive points 31. For this purpose, the anode sheets A from the anode magazine 35 (main magazine) can be brought into adhesive connection with the lower side of the separator web using a contact force. In the same way, the cathode sheets K from the main cathode magazine 39 can be brought into adhesive connection with the upper separator web side using a contact pressure.As soon as the main anode magazine 35 is empty, the backup cathode magazine 37 is integrated into the application process. Similarly, the backup cathode magazine 41 is integrated into the application process as soon as the main cathode magazine 39 is empty.

[0045] In the process arrangement of the Fig. 2, the counterpressure rollers 27, 36 are adjustable transversely to the conveying direction FR between a counterpressure position shown and a retracted position. In the retracted position, contact of the respective counterpressure rollers 27, 36 with the already applied adhesive dots 31 can be avoided.

[0046] At the output side of the application station 13, the separator web 1 equipped with the electrode sheets A, K is guided through a roller gap of the pull roller arrangement 15. The pull rollers are motor-driven in the conveying direction FR, whereby the separator web 1 is pulled through the process arrangement in the conveying direction FR by means of the tensile force built up due to roller friction.

[0047] The separator web 1 is conveyed discontinuously through the application station 11 and the application station 13. If the traction force of the pull roller assembly 15 is interrupted, the separator web 1 stops moving to perform the application and application processes. After the application process is complete, the pull roller assembly 15 is driven again, whereby the separator web section bonded to the electrode sheets A, K is conveyed from the application station 13 to the take-up roll 17, and a subsequent separator web section is subjected to the application and application processes.

[0048] In the further course of the process, the separator track 1 equipped with the electrode sheets A, K is moved to the stacking station 43 ( Fig. 3). In the stacking station 43, the separator web 1 is folded on folding rollers 44 and deposited in a Z-fold under the effect of gravity into an upwardly open magazine housing 45 of the stacking station 43. The Z-folding is performed such that the electrode sheets A, K adhere only to the downward-facing sides of the separator segments 3, while the upward-facing sides of the separator segments 3 are free of electrode sheets A, K.

[0049] To increase the package density of the Z-stack being formed, the stacking station 43 has a hold-down device 47. The hold-down device 47 is arranged outside the magazine housing 45 and is adjustable in the stacking direction and transversely thereto. As can be seen from the Fig. 3, the hold-down device 47 can be adjusted inwardly via a slot-shaped access opening 49 in a magazine housing side wall and can be brought into pressure contact with the separator segment 3 located at the upper end of the stack. Since the electrode blades A, K are each positioned only on the underside of the separator segments 3, direct contact of the hold-down device 47 with the electrode blades A, K, and thus damage to the electrode blades A, K, can be prevented.

[0050] After the forming Z-stack has been pressed, the hold-down device 47 is guided out of the magazine housing 45 in a reversing direction and brought into pressure contact with a subsequent separator segment 3.

[0051] As mentioned above, the separator web 1 is fed discontinuously through the application station 11 and through the application station 13. The compensating unit 9 compensates for the continuous separator web feed via the unwinding roller 7 and the discontinuous separator web conveyance via the application station 11. For this purpose, the compensating unit 9 comprises the dancer roller assembly 19, which is arranged between deflection rollers 53, 55 spaced apart in the conveying direction FR and is mounted for vertical movement. Due to the effect of gravity, the dancer roller assembly 15 can keep the separator web 1 taut.

[0052] In the Fig. 4 shows a process arrangement according to a further comparative example not covered by the invention. The basic structure and the functioning of the Fig. The process arrangement shown in Figure 4 is identical in structure and function to the previous embodiment. Therefore, reference is made to the previous embodiment. In contrast to the previous comparative example, Fig. 4, the electrode sheets A, K are not attached to the separator web 1 by adhesive, but rather by electrostatic attraction forces. For this purpose, a charging device 57 is connected upstream of the application station 11. This charging device consists of a pair of rollers, through whose roller gap the still unloaded separator web 1 is guided. Due to frictional or rolling contact with the pair of rollers, the separator web 1 is charged with a positive electrostatic charge. According to the Fig. 4, the roller pair is grounded via a ground connection 59. In the same way, the anode and cathode magazines 35, 37, 39, 41 are also grounded via a ground connection 59, whereby the electrode sheets A, K adhere to the separator web 1 via electrostatic attraction forces. It is also possible to apply a Teflon protective layer 61 to the electrode sheets A, K, as shown in the Fig. 4. The Teflon protective layer 61 is positively charged and can be removed at the start of the Z-folding process.

[0053] In the Fig.5 to 7 show a process arrangement according to an exemplary embodiment. Accordingly, the adhesive connection between the electrode sheets A, K and the separator web 1 is provided by means of a clamping unit 63, which is arranged downstream of the anode and cathode magazines 35, 37, 39, 41 in terms of process technology. The clamping unit 63 has a plurality of clamping jaw pairs 64 arranged one behind the other in the conveying direction FR. These pairs are driven in the conveying direction FR by means of an endless conveyor belt 65. In this way, the clamping jaw pairs 64 arranged one behind the other can each be successively brought into / out of clamping engagement with the layered assemblies 67, which consist of the electrode sheets A, K and the separator web 1 and are conveyed towards the stacking station 43.

[0054] The respective layer composite 67 can not only be brought into clamping engagement with the clamping jaw pairs 64 of the clamping unit 63. In addition, the clamping unit 63, with its endless conveyor belt 65, forms a pulling device that pulls the separator web 1 in the conveying direction FR through the application station 11 to the stacking station 43. List of reference symbols 1 separator track 3 Separator segment 5 folding edges 7 Unwinding roll 9 Compensation unit 11 Application station 13 order stations 15 Drawbar 17 Take-up roll 19 Dancer roller arrangement 25 application roller 27 Counterpressure roller 29 Order section 31 adhesive dots 33 Transfer roller 35, 37 anode magazines 36 Counterpressure roller 39, 41 cathode magazines 43 Stacking station 45 magazine housing 47 hold-down clamps 49 Access opening 53, 55 pulleys 57 Charging device 59 Mass connection 61 Teflon layer 63 clamping unit 64 pair of clamping jaws 65 endless conveyor belt 67 layer composite A anode sheet K Cathode sheet FR conveying direction

Claims

[1] A method for producing a cell stack for a battery cell, comprising a Z-folding process, in which a separator web (1) is folded in a folding station (43) to form separator segments (3) stacked one above the other in a stacking direction, which segments merge into one another at folding edges (5), wherein electrode sheets (A, K) are arranged between the separator segments (3), wherein an application process takes place before carrying out the Z-folding process, in which the still unfolded separator web (1) is guided through an application station (11) in which the electrode sheets (A, K) are adhered in a fixed position to the separator web (1), so that the electrode sheets (A, K) are securely positioned on the separator web (1) in the Z-folding process, characterized byin that, in order to provide the adhesive connection between the electrode sheets (A, K) and the separator web (1), the application station (11) has a clamping unit (63) which, in terms of process technology, is arranged downstream of the anode and cathode magazines (35, 37, 39, 41), in that the clamping unit (63) has at least one pair (64) of clamping jaws, between which a layer composite (67) consisting of electrode sheet (A, K) and separator web (1) is clamped after the electrode sheet (A, K) has been brought into pressure contact with the separator web (1), in that the clamping unit (63) has a plurality of pairs of clamping jaws (64) arranged one behind the other in the conveying direction (FR), which pairs are conveyed by means of an endless conveyor belt (65) in the conveying direction (FR) to the stacking station (43), so that the pairs of clamping jaws (64) arranged one behind the other can be successively brought into / out of clamping engagement with the layer composites (67) conveyed towards the stacking station (43),and that the clamping unit (63) not only exerts a clamping force on the layer composite (67), but additionally also forms the pulling device located on the output side of the application station (11), which pulls the separator web (1) in the conveying direction (FR) through the application station (11) and further to the stacking station (43). [2] Method according to claim 1, characterized bythat after carrying out the application step, the separator web (1) is fed directly to the stacking station (43), and / or that a motor-driven unwinding roller (7) is arranged on the input side of the application station (11), from which unwinding roller the separator web (1) is continuously fed to the application station (11), that a pulling device (15), in particular a pulling roller arrangement, is arranged on the output side of the application station (11), which pulls the separator web (1) by means of pulling force in the conveying direction (FR) through the application station (11), and / or that the separator web (1) is pulled discontinuously through the application station (11), so that in the event of an interruption in the pulling force, the separator web (1) comes to a standstill in order to carry out the application process, and that after the application process has been completed, when the pulling force is applied to the electrode sheets (A,K) the applied separator web section is conveyed out of the application station (11) and a subsequent separator web section is subjected to the application process., [3] Method according to claim 2, characterized by that a compensation device (9) with a dancer roller arrangement (19) is arranged between the unwinding roller (7) and the application station (11), by means of which the continuous separator web feed by means of the unwinding roller (7) and the discontinuous separator web conveyance through the application station (11) are compensated, and that in particular the dancer roller arrangement (19) is arranged between deflection rollers (53, 55) spaced apart from one another in the conveying direction (FR) and is vertically movable and keeps the separator web (1) taut by its weight. [4] Method according to one of the preceding claims, characterized bythat, to carry out the application process, at least one anode magazine (35, 37) with a counterpressure roller (36) assigned to the opposite separator web side is arranged on one separator web side, and at least one cathode magazine (39, 41) with an assigned counterpressure roller (36) is arranged on the other separator web side, and that, in particular in the application step, the anodes (A) from the anode magazine (35, 37) are brought into adhesive connection with one separator web side by means of a contact force, and the cathodes (K) from the cathode magazine (39, 41) are brought into adhesive connection with the other separator web side by means of a contact force, and that, in particular, on one separator web side, a main anode magazine (35) and a replacement anode magazine (37) are arranged, which is integrated into the application process when the main anode magazine (35) is empty,and that in the same way on the other separator track side a main cathode magazine (35) and a spare cathode magazine (37) are arranged, which is integrated into the application process when the main cathode magazine (35) is empty., [5] Method according to one of the preceding claims, characterized bythat the application process is preceded by an application process in which, in an application station (13), the separator web (1) is coated on both sides with adhesive dots (31) spaced apart from one another in the conveying direction (FR), and that in the subsequent application process, each of the electrodes (A, K) is glued to one of the adhesive dots (31) on the separator web (1), and that, in particular for carrying out the application process, the application station (13) has two pairs of rollers, each pair of rollers consisting of an adhesive application roller (25) and a counter-pressure roller (27) cooperating therewith, and that, in particular, the application roller (25) has an application section (29) which is larger in diameter than the roller diameter, so that the adhesive dots (31) can be set when the application roller (25) is rotating and the separator web is advanced synchronously in the conveying direction (FR),and / or that the counterpressure rollers (27) are adjustable transversely to the conveying direction (FR) between a counterpressure position and a reset position in order to avoid contact of the counterpressure roller (27) with the adhesive dots (31) already set., [6] Method according to one of the preceding claims, characterized by that the electrodes (A, K) are adhesively connected to the two sides of the separator web via electrostatic attractive forces, and that in particular the application process is preceded by an electrostatic charging process in which a charging device (57), in particular a pair of charging rollers, through whose roller gap the separator web (1) is guided, is subjected to a positive electrostatic charge via frictional or rolling contact, and that in particular the electrodes (A, K) are electrostatically charged with a negative charge, whereby the electrodes (A, K) adhere to the separator web (1) via electrostatic attractive forces. [7] Method according to one of the preceding claims, characterized bythat the stacking station (43) has a stacking magazine with an upwardly open magazine housing (45), in which the separator web (1) equipped with the electrode sheets (A, K) is stacked in a Z-fold such that the electrode sheets (A, K) are only adhesively connected to the downward-facing sides of the separator segments (3), that in particular the stacking station (43) has a hold-down device (47) which, in order to increase the package density of the Z-stack, temporarily presses with a hold-down force onto the separator segment (3) located at the upper end of the stack, specifically onto the upward-facing side of the separator segment (3) which is free of electrode sheets (A, K), so that direct contact of the hold-down device (47) with the electrode sheets (A, K) is prevented, that in particular the hold-down device (47) is arranged outside the magazine housing (45) and is adjustable in the stacking direction and transversely thereto is,and that the hold-down device (47) can be adjusted inwards via an access opening (49) in a magazine housing side wall and can be brought into pressure contact with the separator segment (3) located at the upper end of the stack. [8] Process arrangement for carrying out a method according to one of the preceding claims.

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