Method and apparatus for manufacturing an electrode stack

Abstract

The invention relates to a method for manufacturing an electrode stack (2) for a lithium-ion battery of an electrically driven motor vehicle in particular, the electrode stack being composed of an anode (4) and a cathode (6), wherein the cathode (6) is provided in a first storage chamber (8) and is conveyed from the first storage chamber (8) without a fixture only in a first direction (R1) into a chamber (12), wherein the anode (4) is provided in a second storage chamber (10) and is conveyed from the second storage chamber (10) without a fixture only in a second direction (R2) into the chamber (12), wherein the cathode (6) and the anode (4) are stacked alternately in the chamber (12), and wherein the alternately stacked cathode (6) and anode (4) in the chamber (12) are aligned and pressed against each other. The invention also relates to a device (16) for manufacturing such an electrode stack (2).

Description

[0001] The present invention relates to a method and an apparatus for manufacturing an electrode stack composed of an anode and a cathode for a lithium-ion battery.

[0002] Such a lithium-ion battery has at least one battery cell in which an electrode stack is accommodated, the electrode stack having a plurality of sheet-like cathodes (cathode sheets, cathode films) and sheet-like anodes (anode sheets, anode films), wherein the cathodes and anodes are stacked, for example, one above the other, and wherein separators are respectively arranged between the cathodes and anodes.

[0003] An electrode stack having an anode and a cathode stacked one above the other is manufactured, for example, by a so-called single-piece stacking or a so-called Z-fold. Usually, the individual anodes and cathodes are moved in this case by means of a clamping system (gripping system). The clamps of the clamping system pick up the respective electrodes, i.e., the respective anodes or cathodes, convey the electrodes while holding them to the stacking position and place the electrodes there. However, such a clamping system is relatively slow. Therefore, the manufacturing process of such an electrode stack is disadvantageously time-consuming.

[0004] The technical problem to be solved by the present invention is to provide a particularly suitable method and an apparatus for manufacturing an electrode stack of a lithium-ion battery. In particular, a method and / or an apparatus are to be provided for manufacturing the electrode stack as time-saving, cost-saving and / or insensitive to errors as possible.

[0005] This technical problem is solved in terms of the method by the features of claim 1 and in terms of the apparatus by the features of claim 4. Advantageous developments and designs are the subject matters of the dependent claims.

[0006] In a method for manufacturing an electrode stack composed of an anode and a cathode for a lithium-ion battery, for example, of an electrically driven motor vehicle, cathodes are provided in a first storage chamber and anodes are provided in a second storage chamber. The cathodes are conveyed from the first storage chamber into a chamber without a clamp (i.e., without using a clamp) only in a first direction. The anodes are conveyed from the second storage chamber into the chamber without a clamp only in a second direction. The cathodes and anodes are conveyed into the chamber alternately and stacked alternately accordingly. Appropriately, a conveying device is used for conveying the anodes and cathodes, which conveying device, for example, has only rotationally driven conveying rollers.

[0007] The anode and the cathode are collectively referred to as electrodes. These electrodes are particularly designed to be sheet-like. Thus, the electrodes have relatively small dimensions in one spatial direction, in other words, the electrodes are designed to be planar. The electrodes are also referred to as electrode sheets, and the anode and the cathode are accordingly referred to as anode sheets and cathode sheets. Separators are suitably arranged respectively on the (face) side of the provided cathode, i.e., on the planar side of the cathode. In particular, the cathode is covered with separators (diaphragms) on both sides. Thus, in the electrode stack, corresponding separators are arranged between the anode and the cathode. These electrodes suitably have electrical contacts, also referred to as tabs, which are formed by the current collectors of the respective electrodes. Herein, the section of the current collector forming the contact protrudes beyond the end side of the electrode.

[0008] The composite structure composed of the diaphragm and the cathode, i.e., the coated cathode, particularly preferably has the same dimensions as the anode, with exceptions in the area of the electrical contacts if necessary. In other words, the dimensions of the composite structure composed of the diaphragm and the cathode in the plane defined by the respective cathode are the same as the dimensions of the anode in the plane defined by the respective anode. For easier understanding hereinafter, the cathode should be understood as the composite structure composed of the diaphragm and the cathode, i.e., the coated cathode. These statements about the electrodes also apply to the statements about the equipment for manufacturing the electrode stack.

[0009] In the subsequent step, the cathodes and anodes stacked alternately in the chamber are oriented in alignment particularly by means of a die and are pressed against each other particularly by means of a compression unit. In particular, the anode and the cathode are oriented in alignment with each other along their entire outer periphery, with exceptions in the area of the contacts of the anode or the cathode.

[0010] In the case of the fixture system mentioned at the beginning, the electrodes (electrode sheets) are taken out from the respective storage chambers (bins), usually lifted, conveyed, and then placed in, for example, the chamber. Herein, the respective electrodes are grasped by the fixtures. Herein, the fixtures of the fixture system grasping the respective electrodes move accordingly together during the conveyance of the electrodes. Herein, the directions of movement of the electrodes are different when moving, placing, and taking out. Thus, when the anode or the cathode is grasped, the fixture is moved in more than one direction. Compared with such a fixture system, here the cathodes and anodes are conveyed into the chamber without fixtures, i.e., without using a fixture system. The electrodes are conveyed from the storage chamber to the chamber only along their respective single directions. In particular, during this process, the electrodes are not grasped, and / or the device for conveying the electrodes is not moved. In particular, momentum, such as impact or driving the electrodes, is applied to the electrodes only along the first direction or the second direction by means of the conveying device, so that the electrodes are moved into the chamber due to their inertia. Such conveyance is particularly advantageously relatively fast. Thus, the entire process for manufacturing the electrode stack is also faster. Thus, the productivity for manufacturing the electrode stack is advantageously increased, in other words, the output is increased.

[0011] Here, the first direction and the second direction are respectively referred to as the conveying direction. For example, the first direction and / or the second direction is determined by the guide rail.

[0012] According to a suitable extended design, the first direction and the second direction extend in a common plane oriented perpendicular to the chamber bottom plate of the chamber. Here, preferably, the first direction and the second direction are oriented antiparallel to each other, or are substantially antiparallel and only slightly inclined relative to the chamber bottom plate, for example, less than 30°, especially less than 20°. In this way, the cathode and the anode are introduced into the chamber from opposite sides of the chamber. Here, the inclination of the first and / or second direction facilitates the transfer of the respective electrode into the chamber.

[0013] If the electrode is guided by means of a guide rail, the electrode is preferably conveyed such that the end side from which the electrical contact protrudes is oriented perpendicular to the conveying direction, i.e., perpendicular to the guide rail. This avoids damage to the electrical contact on the guide rail during conveyance. In the electrode stack, the electrical contacts of the anode and the cathode are arranged, for example, on a common end side of the electrode stack or on parallel and opposite end sides of the electrode stack. Therefore, the first (conveying) direction and the second (conveying) direction suitably extend substantially antiparallel and in a common plane oriented perpendicular to the chamber bottom plate of the chamber.

[0014] According to a suitable extended design, the cathode conveyed into the chamber and the anode conveyed into the chamber are pressed against the chamber bottom plate by means of an air flow. Therefore, the descent speed of the cathode and the anode is increased, so that the productivity of the electrode stack of this method is relatively high.

[0015] The device is set up and suitable for manufacturing an electrode stack composed of an anode and a cathode for a lithium-ion battery, for example, a (traction) battery of an electrically driven motor vehicle. For this purpose, the device has a chamber for accommodating the anode and the cathode, which chamber is also referred to as a production cylinder (Fertigungszylinder). In addition, the device has a fixture-free conveying device for transferring the anode and the cathode from their respective storage chambers, especially only along the first conveying direction or only along the second conveying direction, into the chamber. That is, the conveying device does not have a fixture for gripping the anode and the cathode during the transfer of the anode and the cathode into the chamber.

[0016] The device has at least two die sets arranged in the chamber, which die sets are movable parallel to the chamber bottom plate of the chamber and perpendicular to each other in order to orient the anode and the cathode accommodated in the chamber in alignment with each other. When the die sets are moved (displaced), the end sides of the cathode and the anode that abut against the respective die sets are oriented in alignment with each other. That is, the end sides of the cathode and the anode are parallel to each other and parallel to the respective die sets.

[0017] Furthermore, the device has a compression unit that can move perpendicular to the chamber bottom plate. The compression unit is used to generate a pressing force acting on the anodes and cathodes that are appropriately stacked alternately in the chamber and oriented aligned with each other.

[0018] Since the anodes and cathodes are oriented aligned with each other by means of a die, an orientation that is particularly insensitive to alignment errors of the anodes and cathodes relative to each other is achieved.

[0019] According to a suitable expansion design, the conveying device has corresponding conveying rollers that are only rotationally driven for transferring the anodes and cathodes. That is, the roller elements cannot move translationally but are fixed in position, and the roller elements are rotationally driven to transfer the anodes and cathodes. The roller elements are particularly designed as rollers, wheels, or rollers. For example, the roller elements have a rough surface such that the corresponding electrodes are conveyed due to the friction between the rotating roller elements and the electrodes. In short, the device is fixture-free. Similar to the above method, a device is thus achieved by means of which an electrode stack can be manufactured more time-efficiently compared to a device with the fixture system mentioned at the beginning.

[0020] For example, the conveying device also has guide rails by means of which the anodes or cathodes conveyed by the conveying rollers are guided into the chamber.

[0021] For example, when the die aligns the anodes and cathodes with each other, it is moved respectively towards a fixed abutment, in particular the chamber wall, where the abutment enables the end sides of the cathode and anode to be abutted against each other and aligned. However, according to a suitable design of the device, four dies are arranged in the chamber, and two of these dies can move along and against a first movement direction (displacement), and the other two dies can move along and against a second movement direction perpendicular to the first direction. In this way, each end side of the anode and cathode is oriented by means of the corresponding die. Appropriately, the first movement direction or the second movement direction lies in the plane in which the conveying direction extends. After the die squeezes the anodes and cathodes against each other, it can move away from the electrode stack. Thus, it is easy to remove the electrode stack from the chamber.

[0022] The compression unit can suitably move into the chamber and in particular between the dies that orient the anodes and cathodes.

[0023] According to an advantageous expansion design, the compression unit has air nozzles on its side facing the chamber bottom plate. Preferably, the compression unit has a plurality of air nozzles on its side facing the chamber bottom plate. These air nozzles are used to generate an air flow directed towards the chamber bottom plate. By means of the air flow, the anodes and cathodes conveyed into the chamber are pressed towards the chamber bottom plate, so that the descent speed of these anodes and cathodes is increased. Thus, the productivity of the electrode stack is advantageously increased.

[0024] According to a suitable design, at least one of the pressing dies has a void portion for accommodating the electrical contacts of the cathode and / or anode during orientation. That is, the void pressing die is placed on the side of the corresponding electrical connector. Depending on the design of the electrical contacts of the anode and cathode, in particular the arrangement, one of the pressing dies has a void portion for the electrical contacts of the anode and cathode. Alternatively, one of the pressing dies has two spaced-apart void portions, where one void portion is provided for the electrical contact of the anode and the other void portion is provided for the electrical contact of the cathode. As a further alternative, in particular two pressing dies opposite each other each have a void portion, where one of these void portions is provided for the electrical contact of the anode and the other void portion is provided for the electrical contact of the cathode.

[0025] According to a suitable design, a negative pressure can be generated by means of a roller element. Due to this negative pressure, the electrodes are separated from the electrodes stored in the corresponding storage chamber and are accelerated, i.e., momentum is applied, along the corresponding conveying direction. For this purpose, for example, one or more air channels coupled to a suction pump are arranged in the roller element. In summary, both the separation of the cathodes and the separation of the anodes provided in the corresponding storage chamber are achieved, and the conveyance of the cathodes and anodes into the chamber by means of the corresponding conveying rollers is also achieved.

[0026] According to an advantageous expansion design of the device, the chamber bottom plate is formed by a conveyor belt that is particularly height-adjustable. After the anode and cathode are pressed against each other to form an electrode stack, the electrode stack can thus simply be moved away from the pressing die by lowering the chamber bottom plate. For example, the compression unit descends together with the chamber bottom plate. In particular, in this way, the electrode stack is released from the chamber in a relatively reliable manner to prevent damage, such as damage caused by the electrode stack getting caught on one of the pressing dies or one of the fixed abutments. For example, the electrode stack is subsequently conveyed to a warehouse or provided for further assembly of a lithium-ion battery.

[0027] Embodiments of the present invention are described in more detail below with the aid of the accompanying drawings. In the drawings:

[0028] Figure 1 A flowchart showing a method for manufacturing an electrode stack is shown, where the provided anode and the provided cathode are conveyed into the chamber without a fixture.

[0029] Figure 2a A front view of a device for manufacturing an electrode stack is schematically shown, where the device has a conveying device with only rotationally driven conveying rollers for conveying the anode and cathode into the chamber of the device, and where the device has pressing dies for orienting the cathode and anode aligned with each other.

[0030] Figure 2bThe front view of the device is schematically shown, wherein the chamber bottom plate consists of a height-adjustable conveyor belt by means of which the electrode stack can be transported, and

[0031] Figure 3 The top view of the device is schematically shown, wherein the electrical contacts of the anode and the cathode are received in the cutouts of the die.

[0032] Corresponding parts and dimensions are always provided with the same reference numerals in all the drawings.

[0033] In Figure 1 The flow chart shown represents a method for manufacturing an electrode stack 2 composed of an anode 4 and a cathode 6. Here, the electrode stack 2 is provided for a lithium-ion battery not further shown, for example, a (traction) battery for a motor vehicle.

[0034] In a first step A, a sheet-like cathode 6 is provided in a first storage chamber 8, and a sheet-like anode 4 is provided in a second storage chamber 10. The anode 4 and the cathode 6 are also collectively referred to as electrodes. Here, the cathode 6 is covered with separators (diaphragms) on both sides, wherein the composite structure composed of the diaphragm and the cathode 6, i.e., the coated cathode 6, has the same dimensions as the anode 4. Therefore, in the electrode stack 2, corresponding separators are arranged between the anode 4 and the cathode 6.

[0035] In a subsequent second step B, the cathode 6 is conveyed from the first storage chamber 8 to the chamber 12 without a fixture only along a first (transport) direction R1. In a similar manner, the anode 4 is conveyed from the second storage chamber 10 to the chamber 12 without a fixture only along a second (transport) direction R2. During this process, the cathode 6 and the anode 4 are alternately stacked in the chamber 12, wherein one of the cathodes 6 is first conveyed into the chamber 12. In step B, the first direction R1 and the second direction R2 extend in a common plane perpendicular to the chamber bottom plate 14.

[0036] Here, in a third step C, the cathode 6 conveyed into the chamber 12 and the anode 4 conveyed into the chamber 12 are pressed against the chamber bottom plate 14 of the chamber 12 by means of an air flow L so as to increase the downward speed of the anode 4 and the cathode 6 towards the chamber bottom plate 14.

[0037] The cathode 6 and the anode 4 alternately stacked in the chamber 12 are aligned and oriented in a fourth step D and pressed against each other in a fifth step E. The thus formed electrode stack 2 is provided in a sixth step F for manufacturing a lithium-ion battery.

[0038] In Figure 2a 、 Figure 2b And Figure 3 The device 16 for manufacturing the electrode stack 2 according to the method especially shown in Figure 1 is schematically shown.

[0039] Device 16 has a first storage chamber 8 and a second storage chamber 10, in which the cathode 6 or the anode 4 is provided to fabricate the electrode stack 2. Here, each of the two storage chambers 8 and 10 has a lifting unit 18, and when one of the cathodes 6 or one of the anodes 4 is taken out, the cathode 6 or the anode 4 remaining in the corresponding storage chamber 8 or 10 is displaced toward the guide rail 20 of the conveying device 22 by means of this lifting unit.

[0040] The conveying device 22 also has two conveying rollers 24 designed as rollers, and the two conveying rollers are respectively arranged between the guide rails 20 and their rotation directions are respectively shown by arrows. Here, the conveying rollers 24 are position-fixed, that is, they cannot move translationally and are only rotationally driven. The conveying rollers 24 have devices such as air channels designed to be connected to a vacuum pump or an air extraction pump in a manner not shown in detail, and a negative pressure can be generated by means of this device.

[0041] When the conveying rollers 24 rotate, the anode 4 or the cathode 6 above the corresponding storage chamber 10 or 8, that is, facing the conveying device 22, is separated from the anode 4 or the cathode 6 stored in the corresponding storage chamber due to this negative pressure and is accelerated along the corresponding conveying direction R2 or R1. During this process, the guide rail 20 prevents the cathode 6 and the anode 4 from deviating uncertainly from their conveying direction R1 or R2 during their conveyance. In short, the guide rail 20 serves as a guiding device for the conveyed anode 4 and cathode 6.

[0042] In addition, the device 16 has a chamber 12 with a chamber bottom plate 14, and the conveyed anode 4 and cathode 6 are alternately introduced into this chamber 12. As Figure 2a shown, the anode 4 and the cathode 6 are arranged relative to each other uncertainly after being accommodated in the chamber 12, that is, they are not aligned in a direction perpendicular to the chamber bottom plate 14.

[0043] The device 16 also has four pressing dies 26, and for the sake of clarity, only two pressing dies are shown in Figure 2a 、 Figure 2b . Here, these pressing dies 26 can move parallel to the chamber bottom plate 14. Two of these pressing dies 26 that are opposed to each other can also move along and against a first displacement direction V1, and the other two pressing dies 26 can move along and against a second displacement direction V2 oriented perpendicular to the first displacement direction V1. In order to orient the cathode 6 and the anode 4 aligned with each other, as can be seen especially in Figure 3 , the pressing dies 26 are moved toward each other. Here, the first displacement direction V1 extends in or parallel to the plane in which the first conveying direction R1 and the second conveying direction R2 extend.

[0044] Device 16 includes a compression unit 28. The compression unit 28 has a plurality of air nozzles 32 on a side portion 30 facing the chamber bottom plate 14, and an air flow L directed towards the chamber bottom plate 14 can be generated by means of these air nozzles. By means of the air flow L, the anodes 4 and cathodes 6 delivered into the chamber 12 are pressed towards the chamber bottom plate 14, so that the downward speed of these electrodes towards the chamber bottom plate 14 is increased.

[0045] The oriented anodes 4 and cathodes 6 are squeezed against each other by means of the compression unit 28. For this purpose, the compression unit 28 moves into the chamber 12 perpendicular to the chamber bottom plate 14 and applies a squeezing force F to the anodes 4 and cathodes 6 there. P 。

[0046] The chamber bottom plate 14 consists of a height-adjustable conveyor belt. Accordingly, the electrode stack 2 formed by the mutually squeezed anodes 4 and cathodes 6 can be moved away from the mold 26 by lowering the chamber bottom plate 14 designed as a height-adjustable conveyor belt. Here, the lowering of the chamber bottom plate 14 is indicated by an arrow. The electrode stack 2 is transferred onto a conveyor belt 34 by means of the lowering conveyor belt. The conveyor belt 34 is used to transport the electrode stack 2 to a warehouse and / or other equipment for manufacturing lithium-ion batteries.

[0047] Each of the anodes 4 and each of the cathodes 6 respectively have electrical contacts 36, which are formed by the current collectors of the respective electrodes 4 or 6. Here, the electrical contacts 36 protrude beyond the end sides of the respective electrodes 4 or 6. For the sake of clarity, the electrical contacts 36 are not shown in Figure 2a and Figure 2b . As can be seen from Figure 3 , the electrical contacts of the anodes 4 and cathodes 6 are arranged on opposite, parallel-extending side portions of the electrode stack 2. Accordingly, the two opposite molds 26 respectively have cutouts 38, wherein one of these cutouts 38 is provided for receiving the electrical contact 36 of the anode 4, and the other cutout 38 is provided for receiving the electrical contact 36 of the cathode 6.

[0048] The present invention is not limited to the above embodiments. Instead, those skilled in the art can derive other variants of the present invention therefrom, as long as the technical solution of the present invention is not departed from. In particular, all the individual features described with respect to the embodiments can also be combined with each other in different ways, as long as the technical solution of the present invention is not departed from.

[0049] List of reference numerals

[0050] 2 Electrode stack

[0051] 4 Anode

[0052] 6 Cathode

[0053] 8 First storage chamber

[0054] 10 Second storage chamber

[0055] 12 Chamber

[0056] 14 Chamber bottom plate

[0057] 16 Device

[0058] 18 Lifting unit

[0059] 20 Guide rail

[0060] 22 Conveying device

[0061] 24 Conveying roller

[0062] 26 Die

[0063] 28 Compression unit

[0064] 30 Side part

[0065] 32 Air nozzle

[0066] 34 Conveyor belt

[0067] 36 Electrical contact

[0068] 38 Empty part

[0069] A Method step, providing

[0070] B Method step, conveying

[0071] C Method step, pressing

[0072] D Method step, orienting

[0073] E Method step, extruding

[0074] F Method step, providing

[0075] F P Extrusion pressure

[0076] L Air flow

[0077] R1 First direction

[0078] R2 Second direction

[0079] V1 First moving direction

[0080] V2 Second moving direction

Claims

1. A method for manufacturing an electrode stack (2) for a lithium-ion battery of an electrically driven motor vehicle in particular, the electrode stack being composed of an anode (4) and a cathode (6), - Among them, The cathode (6) is provided in a first storage chamber (8) and is conveyed from the first storage chamber (8) to the chamber (12) without a fixture only along a first direction (R1), - wherein the anode (4) is provided in a second storage chamber (10) and is conveyed from the second storage chamber (10) to the chamber (12) without a fixture only along a second direction (R2), wherein the cathode (6) and the anode (4) are alternately stacked in the chamber (12), and - wherein the cathode (6) and the anode (4) alternately stacked in the chamber (12) are aligned and pressed against each other, wherein momentum is applied to the electrodes only along the first direction or the second direction by means of a conveying device, such that the electrodes are moved into the chamber due to their inertia, wherein the conveying device (22) has corresponding rotationally driven conveying rollers (24) for transferring the anode (4) and the cathode (6).

2. The method according to claim 1, wherein The first direction (R1) and the second direction (R2) extend in a common plane oriented perpendicular to the chamber bottom plate (14).

3. The method according to claim 1 or 2, characterized in that, The cathode (6) conveyed into the chamber (12) and the anode (4) conveyed into the chamber (12) are pressed against the chamber bottom plate (14) by means of an air flow (L).

4. An apparatus (16) for manufacturing an electrode stack (2) for a lithium-ion battery of an electrically driven motor vehicle in particular, the electrode stack being composed of an anode (4) and a cathode (6), the apparatus having - a chamber (12) for accommodating the anode (4) and the cathode (6); - a fixtureless conveying device (22) for transferring the anode (4) and the cathode (6) from their respective storage chambers (8, 10) to the chamber (12); - at least two pressing dies (26) arranged in the chamber (12), which pressing dies are movable parallel to the chamber bottom plate (14) and perpendicular to each other in order to align the anode (4) and the cathode (6) accommodated in the chamber (12); and - A compression unit (28) movable perpendicular to the chamber bottom plate (14) for generating a pressing force (F P ) acting on anodes (4) and cathodes (6) stacked and oriented aligned with each other in the chamber (12) wherein the conveying device is designed to apply momentum to the electrodes only along the first direction or the second direction, such that the electrodes are moved into the chamber due to their inertia, wherein the conveying device (22) has corresponding rotationally driven conveying rollers (24) for transferring the anode (4) and the cathode (6).

5. The device (16) according to claim 4, characterized in that, Four pressing dies (26) are arranged in the chamber (12), wherein two of these pressing dies (26) can move along and against a first movement direction (V1), and the other two pressing dies (26) can move along and against a second movement direction (V2) perpendicular to the first direction (V1).

6. The device (16) according to claim 4 or 5, characterized in that, The compression unit (28) has an air nozzle (32) on its side (30) facing the chamber bottom plate (14), which air nozzle is used to generate an air flow directed towards the chamber bottom plate (14).

7. The device (16) according to claim 4 or 5, characterized in that, At least one of the pressing dies (26) has a void (38) for accommodating the electrical contacts (36) of the cathode and / or the anode (4).

8. The device (16) according to claim 4 or 5, characterized in that, A negative pressure can be generated by means of a roller element (24), wherein the anode (4) or the cathode (6) is transferred from its respective storage chamber (8, 10) into the chamber (12) due to this negative pressure.

9. The device (16) according to claim 4 or 5, characterized in that, The chamber floor (14) is formed by a conveyor belt which is in particular height-adjustable.

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