Processes for manufacturing battery cells

Abstract

The invention relates to a method for manufacturing battery cells (54) filled with an electrolyte and having at least one filling opening (56) on an accessible side. The following process steps are carried out: a number of battery cells (54) filled with the electrolyte are arranged on a workpiece carrier (50). The at least one filling opening (56) on each of the battery cells (54) is simultaneously closed by means of a degassing device (58). Subsequently, a forming process (16) is carried out on the battery cells (54) mounted on the workpiece carrier (50), while all battery cells (54) are degassed in parallel. Thereafter, in a dry environment (24), the at least one filling opening (56) is opened by removing the degassing device (58) and the electrolyte (20) is refilled.Then, a permanent closure of the at least one filling opening (56) is effected by joining a lid in a material-bonded manner.

Description

Technical field

[0001] Method for manufacturing battery cells filled with an electrolyte and having at least one filling opening on an accessible side. State of the art

[0002] DE 10 2014 208 225 A1 discloses a device for forming battery cells in a forming stage or forming electronics, which includes power electronics. The forming stage or forming electronics provide a regulated output voltage or a regulated output current for the series or parallel forming of the battery cells to be formed. These include integrated power electronics with power semiconductors, at least one of which influences the forming current of the battery cells to be formed with integrated power electronics.

[0003] DE 10 2014 208 214 A1 discloses a device comprising a battery cell with a first cell terminal and a second cell terminal. The battery cell has at least one communication interface for data exchange with at least one forming stage. Furthermore, the battery cell has integrated monitoring sensors and integrated battery state detection sensors with a memory for battery cell forming data.

[0004] DE 10 2017 217 318 A1 relates to a charging device and a charging method for charging at least one battery cell, in particular a forming device, as well as a forming method by which several battery cells can be charged and discharged repeatedly in a single process. A contact block electrically contacts the two terminals of the battery cell to be charged. A positioning device moves the battery cell relative to the contact block into a charging position. A connecting element establishes an electrical connection between a voltage source and the contact block. A flexible and electrically conductive connecting element of the connecting element is electrically connected to the contact block and the voltage source. The flexible connecting element allows the connected contact block to be moved in any direction relative to the connected voltage source.

[0005] WO 2018 / 162 719 A1 relates to a forming plant for forming battery cells with a forming chamber in which a contacting unit for contacting the battery cells for forming is arranged, as well as a feeding device with which battery cells arranged on a workpiece carrier can be moved in and out of the free space of the forming chamber from outside the forming chamber.

[0006] WO 2020 / 239 927 A1 relates to a product carrier system with a product carrier and with cell carriers for forming battery cells, wherein the product carrier has a guide device for receiving the cell carriers, wherein the cell carriers have contact elements for contacting an inserted battery cell and the cell carriers can be clamped in the product carrier and connections for contacting the cell carriers are centrally grouped into electrical connections on the product carrier.

[0007] DE 10 2021 203 586 A1 relates to a battery arrangement comprising at least one battery cell, a housing enclosing a volume, and at least one first electrode foil of a first electrode type, a second electrode foil of a second electrode type, and a separator material arranged between them. Furthermore, a liquid electrolyte is provided, and the battery cell has at least one first valve and one second valve. The battery also includes a first connecting line, which is connected to the volume via at least the first valve.

[0008] EP 4 099 460 A1 relates to a method for manufacturing a battery cell comprising a housing with a first volume and, in the first volume, a plurality of electrodes arranged one above the other and an electrolyte that can be introduced into the first volume through an opening in the housing. The method further comprises a process step for degassing via the opening and for sealing the opening with a sealing element that forms a non-metallic connection with the opening.

[0009] DE 10 2022 111 107 A1 relates to a closure device for temporarily sealing a degassing opening in a battery housing, comprising a closure element. This element is designed to be positioned within the degassing opening by sealing against a wall of the housing bounded by the degassing opening and having a degassing channel designed as a through-opening. The degassing channel is closed by means of a pressure relief valve of the shut-off device, which is designed such that the pressure relief valve opens when a defined overpressure prevails on an inner surface of the casing, thereby releasing the degassing channel. Description of the invention

[0010] Method for manufacturing battery cells filled with an electrolyte and having at least one filling opening on an accessible side, comprising the following process steps: a) Arranging a number of battery cells filled with electrolytes onto a workpiece carrier, b) temporary closure of at least one filling opening of all battery cells simultaneously by a degassing device, c) Performing a forming process on the number of battery cells arranged on the workpiece carrier during a parallel degassing of all battery cells, d) Opening the at least one filling port of the battery cells in a dry environment by removing the degassing device and refilling the electrolyte and e) permanent sealing of at least one filling opening of the battery cells by joining a lid in a material-bonded manner.

[0011] The method proposed according to the invention advantageously achieves that gases generated during a forming process of battery cells to be formed are drained away by applying a negative pressure and that the penetration of moisture into the interior of the battery cells is effectively prevented.

[0012] Advantageously, in the method proposed according to the invention, the at least one filling opening of each of the battery cells arranged on the workpiece carrier is closed by a closure of the degassing device according to process step b). Advantageously, in the method proposed according to the invention, the temporary closure of the at least one filling opening can be carried out simultaneously on all battery cells to be formed and degassed on a workpiece carrier.

[0013] Advantageously, in the method proposed according to the invention, the degassing device is connected to a vacuum source via an open shut-off valve during the execution of process step c), and gases generated during the forming process are extracted from the battery cells, while at the same time the ingress of moisture into the interior of the battery cells is effectively prevented.

[0014] The method proposed according to the invention is further characterized in that, during the execution of process step c), the at least one filling opening on each of the battery cells is temporarily closed via the temporary closures of the degassing device, and a microclimate is created at the battery cells. This advantageously eliminates the need for a complex drying chamber, which has a very favorable effect on manufacturing costs.

[0015] Furthermore, the invention relates to a degassing device for a forming station for battery cells that are filled with an electrolyte and have at least one filling opening, wherein a number of battery cells are mounted on a workpiece carrier for carrying out the above method, wherein the degassing device is essentially tubular and can be connected to an extraction system by means of a shut-off valve, and wherein the degassing device has a number of closures that degas the respective battery cells during the forming process.

[0016] The degassing device proposed according to the invention is further characterized in that the degassing device has several pipe sections, around the circumference of which the closures are arranged in rows. The closures can, for example, be formed on short connecting nozzles on one side of the circumference of the pipe sections. These, in turn, are advantageously placed in a sealing manner onto the filling arrangement of the prismatically shaped battery cells within an empty recess.

[0017] In the degassing device proposed according to the invention, it is further provided that it is received on a workpiece carrier in supports, such that the pipe sections are oriented above the at least one filling opening corresponding to the number of battery cells received on the workpiece carrier.

[0018] In the degassing device proposed according to the invention, it is further provided that the pipe sections are movable in a direction of rotation, such that the closures on the circumference on one side of the pipe sections close the filling opening of the number of battery cells arranged on the workpiece carrier and connect it to an extraction system.

[0019] The degassing device proposed according to the invention further provides that it is attached to an upper side of the workpiece carrier either by means of eccentric quick-release fasteners, lever mechanisms, or screws.

[0020] Furthermore, the invention relates to the use of the method for manufacturing battery cells, and furthermore, the invention relates to the use of the degassing device for manufacturing battery cells. Advantages of the invention

[0021] The quality of a battery cell depends on preventing moisture from penetrating it. This also applies during the manufacturing phase. To prevent this, either the processes must be carried out in a dry environment or the respective battery cell must be temporarily sealed. The solution proposed according to the invention uses a degassing device to temporarily seal the at least one filling opening of the battery cell after it is placed on the cell being formed and degassed during the forming process. This creates a microclimate on the workpiece carrier. Furthermore, the temporary sealing of the filling opening by means of closures provided on the degassing device prevents moisture from entering the interior of the battery cell.

[0022] The degassing unit allows the cells to be degassed during the first forming step, as it is connected to an extraction system during the forming process. Opening a shut-off valve creates a negative pressure above the degassing unit and the closures that seal the respective filling openings. This pressure allows the gases generated during the forming process to be vented, preventing moisture ingress.

[0023] Without such a degassing system, either the entire forming area would have to be located in a dry room, or temporary closures would have to be removed from each forming chamber and reinstalled after the process. With approximately 150 to 300 forming chambers per production line, this represents an enormous and extremely labor-intensive effort that is difficult to automate.

[0024] The method proposed according to the invention allows, for example, 32 prismatic cells arranged on the top side of a workpiece carrier to be connected simultaneously with a degassing device during a first forming step, so that, for example, 32 prismatic cells can be degassed batchwise during the forming process.

[0025] The degassing device proposed according to the invention is oriented above prismatic cells arranged in groups on the upper surface of the workpiece carrier. The degassing device is supported by brackets and comprises individual pipe sections. These pipe sections are interconnected. The brackets absorb the forces required for sealing between the closures, which are arranged in rows around the circumference of the pipe sections and occur when the at least one battery opening is closed. In the closed state, i.e., when the closures arranged in rows around the circumference of the pipe sections protrude into the filling openings of the battery cells, a microclimate is created within the battery cells, eliminating the need for a dry environment.

[0026] The components of the battery cell, or the electrolyte it contains, in liquid or gaseous form, can be harmful to health. This is especially true during the initial phase of the chemical process. Furthermore, these components can also be flammable. The solution proposed according to the invention allows the degassing device to seal the battery cell, which may be prismatically shaped, for example, preventing these substances from escaping into the environment and thus eliminating any health risks. Additionally, targeted degassing or venting can be carried out after the degassing device is installed. Brief description of the drawings

[0027] The invention is described in more detail below with reference to the drawings.

[0028] They show: Fig. 1. A schematic representation of a manufacturing process according to the state of the art, Fig. 2 a schematic sequence of the process steps according to the method proposed according to the invention using a degassing device and Fig. 3 a perspective view of a workpiece carrier with prismatic battery cells mounted on it in groups, as well as a degassing device associated with them.

[0029] According to the representation Fig. Figure 1 schematically depicts a prior art method for manufacturing battery cells 54, according to which the first process step involves filling 10 of the battery cells 54 with electrolyte. This filling 10 is followed by storage 12 of the battery cells 54, after which their electrical testing 14 is performed. In the subsequent process step, the battery cells 54 are formed 16 and degassed in a dry room 24 and in a dry environment 24, as is the filling 10 with electrolytes.

[0030] Following the formation 16, the battery cells 54 undergo another electrical test 18 before being refilled 20 with electrolyte in a dry room 24 or a dry environment. Also in a dry room 24 or a dry environment, the filling opening 22 is closed, in particular permanently closed, by means of a material-bonded joining process. For example, a cover is permanently welded onto the filling openings 56 of the battery cells 54. Embodiments of the invention

[0031] In the following description of embodiments of the invention, identical or similar elements are designated by the same reference numerals, and repeated descriptions of these elements are omitted in individual cases. The figures represent the subject matter of the invention only schematically.

[0032] According to the representation Fig. 2 shows that in a dry room 24 or a dry environment analogous to the representation according to Fig. 1. The filling of 10 battery cells 54 with electrolyte is carried out.

[0033] Also in a dry environment 24, a temporary closure 32 of filling openings 56 is performed (see Fig. 3) of battery cells 54, as also in Fig. Figure 3 shows the process. The temporary sealing 32 of at least one filling opening 56 on an accessible side of the, for example, prismatically shaped battery cells 54 is carried out by attaching a degassing device 58. By attaching the degassing device 58, a microclimate is created on a workpiece carrier 50 at the battery cells 54, which are to be formed and degassed in parallel with the forming process. Furthermore, by attaching a degassing device 58, the ingress of moisture into the interior of the battery cell 54 can be effectively prevented.

[0034] The degassing device 58, installed according to the method proposed in the invention, enables the degassing of the battery cells 54 during a first forming step. In the method proposed in the invention, the forming process 34 of the battery cells 54 takes place during the period in which the degassing device 58 is installed on the battery cells 54 being formed and degassed. Without the degassing device 58, either the entire forming area for the battery cells 54 would have to be located in a dry room 24 or in a dry environment, or alternatively, a temporary seal for the battery cells 54 being formed and degassed would have to be removed from each forming chamber and reinstalled after the process. With an estimated 150 to 300 forming chambers per production line, this would result in a very high, particularly labor-intensive effort.

[0035] This can be saved by the procedure proposed according to the invention as soon as, after the forming process 34 of the battery cells 54 to be formed and degassed has been carried out in a dry environment 24, a temporarily attached closure 32 is removed. The removal 36 of a temporarily effective closure 32 of the at least one filling opening 56 on the battery cells 54 is followed by a refilling 20 of electrolyte before the at least one filling opening 56 on an accessible side of a battery cell 54, for example, a prismatically shaped one, is permanently closed, for example, by means of a welding process.

[0036] The representation in Fig. Figure 3 shows a schematic representation of a possible embodiment of a degassing device with which the method proposed according to the invention is carried out.

[0037] From the representation according to Fig. Figure 3 shows that on a top surface 52 of a workpiece carrier 50, which is rectangular in shape here, a group arrangement of prismatically shaped battery cells 54 is made. On the top surface 52 of the workpiece carrier 50, there are prismatic battery cells 54 arranged in four groups 74, 76, 78, 80, i.e., a total of 32 prismatically shaped battery cells 54.

[0038] On the easily accessible upper side of each of the prismatically shaped battery cells 54 there is at least one filling opening 56.

[0039] As the perspective top view according to Fig. As further shown in Figure 3, the degassing device 58 runs above the easily accessible upper surface of the prismatically shaped battery cells 54. The degassing device 58 comprises individual pipe sections 60, connected here to one another, which are received in supports 62 when viewed in the longitudinal direction of the workpiece carrier 50. Individual closures 82 are provided on the pipe sections 60 in rows 86, enabling the temporary closure of at least one battery opening 56 of the battery cells 54. The closures 82 are advantageously arranged in rows 86 along the circumference 88 of the pipe sections 60. For the sake of clarity, only one degassing device 58 is shown; the other has been omitted for the sake of clarity in order to show the supports 62, which comprise first and second columns 64, 66 arranged parallel to each other at a height corresponding to the height of the prismatic battery cell 54.

[0040] From the perspective top view according to Fig. Figure 3 further shows that a shut-off valve 68 is arranged at one end of the degassing device 58. The degassing device 58, or the longitudinally connected pipe sections 60, can be connected to a vacuum source via the shut-off valve 68. When the at least one filling opening 56 on the top of the prismatic battery cells 54 is temporarily closed, a vacuum is created inside the battery cell 54, allowing gases generated during the forming process to be extracted via the shut-off valve 68 (which is open in this case) and the vacuum in the extraction system 70.

[0041] Out of Fig. It can further be seen from Figure 3 that the individual interconnected pipe sections 60 are advantageously placed linearly onto the filling openings 56 of the battery cells 54 with the closures 82, designed as short connecting spigots, during a linear lowering movement 30. The placement 30 of the degassing device 58 enables, in a particularly advantageous manner with regard to the cycle times to be observed during formation and the degassing that occurs in parallel, a simultaneous temporary closure of all filling openings 56 on the top side of the prismatically designed battery cells 54.

[0042] The sealing forces that occur between the closures 82 arranged in rows 86 when contacting and closing the filling openings 56 of the battery cells 54 are absorbed by the supports 62.

[0043] For example, as in Fig. Figure 3 shows that the workpiece carrier 50 is fitted on its upper side 52 with the aforementioned four groups 74, 76, 78, 80, each consisting of eight prismatic battery cells 54, and two degassing devices 58 are provided, so that with the in Fig. 3 exemplary workpiece carriers 50 simultaneously subject 32 battery cells 54 to a forming process, in which the gases generated inside the battery cells 54 during the forming process can be extracted via said degassing devices 58, which extend parallel to each other.

[0044] Another advantageous effect of the degassing device 58 proposed according to the invention is that, at the moment when the at least one filling opening 56 on the top of the easily accessible side of the prismatic battery cell 54 is closed by the closures 82 of the tube sections 60, the ingress of moisture into the interior of the battery cells 54 is excluded.

[0045] In the closed state, i.e., in the state in which the closures 82 arranged in individual rows 86 seal the filling opening 56 of the prismatic battery cells 54, a microclimate prevails within them. If the forming process 34 is now carried out with the degassing device 58 activated, the degassing devices 58, which extend parallel to each other, are connected to a vacuum source via the open shut-off valve 68, so that by applying the vacuum the gases produced during formation are drawn out of the interior of the battery cells 54 and, in addition, the ingress of moisture into them is prevented.

[0046] The degassing device 58, comprising several interconnected pipe sections 60, can be clamped to the workpiece carrier 50, for example, by means of eccentric quick-release fasteners, suitable lever mechanisms or by means of a screw connection.

[0047] With regard to the embodiment of the degassing device 58 shown here, it should be noted that the individual interconnected pipe sections 60 of the degassing device 58 are held in place by means of the supports 62. The supports 62 also absorb the sealing forces that occur as soon as the closures 82 on the circumference 88 of the pipe sections 60 close the individual filling openings 56 of the prismatically shaped battery cells 54.

[0048] Instead of the in Fig. In the view shown in Figure 3 of the workpiece carrier 50, which accommodates 32 prismatic battery cells 54, a larger or smaller number of prismatic battery cells 54 to be formed and simultaneously degassed can also be arranged on the top 52 of the workpiece carrier 50. This depends on the size of the forming chamber of the forming station used.

[0049] The invention is not limited to the embodiments described here and the aspects highlighted therein. Rather, within the scope specified by the claims, a multitude of modifications are possible that fall within the bounds of what is considered skilled in the art. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2014 208 225 A1

[0002] DE 10 2014 208 214 A1

[0003] DE 10 2017 217 318 A1

[0004] WO 2018 / 162 719 A1

[0005] WO 2020 / 239 927 A1

[0006] DE 10 2021 203 586 A1

[0007] EP 4 099 460 A1

[0008] DE 10 2022 111 107 A1

[0009]

Claims

[1] A method for producing battery cells (54) filled with an electrolyte and having at least one filling opening (56) on an accessible side, comprising the following process steps: a) Arranging a number of battery cells (54) filled with electrolyte onto a workpiece carrier (50), b) temporary closure of at least one filling opening (56) of all battery cells (54) simultaneously by a degassing device (58), c) Performing a forming process (16) on the number of battery cells (54) applied to the workpiece carrier (50) during a parallel degassing of all battery cells (54), d) Opening the at least one filling opening (56) of the battery cells (54) in a dry environment (24) by removing the degassing device (58) and refilling the electrolyte (20) and e) permanent sealing of at least one filling opening (56) of the battery cells (54) by joining a lid in a material-bonded manner. [2] Method according to claim 1, characterized by , that the at least one filling opening (56) of each of the battery cells (54) arranged on the workpiece carrier (50) is closed by a temporary closure (82) of the degassing device (58) according to process step b). [3] Method according to claims 1 to 2, characterized by , that the degassing device (58) is connected to a vacuum source via an open shut-off valve (68) during the execution of process step c) and that gases generated during the forming process are extracted from the battery cells (54). [4] Method according to claims 1 to 3, characterized by, that during the execution of process step c) the at least one filling opening (56) on each of the battery cells (54) is temporarily closed via the temporary closures (82) of the degassing direction (58) and that moisture does not enter the battery cells (54). [5] Degassing device (58) of a forming station for battery cells (54) which are filled with an electrolyte and have at least one filling opening (56), wherein a number of battery cells (54) are mounted on a workpiece carrier (50), for carrying out the method according to claims 1 to 4, characterized by , that the degassing device (58) is essentially tubular and is connected to a suction device (70) by means of a shut-off valve (68), wherein the degassing device (58) has a number of closures (82) through which the battery cells (54) are degassed during formation. [6] Degassing device (58) according to claim 5, characterized by , that the degassing device (58) comprises several pipe sections (60) on the circumference (88) of which the closures (82) are arranged in rows (86). [7] Degassing device (58) according to claims 5 to 6, characterized by , that these are received on a workpiece carrier (50) in supports (62) such that the pipe sections (60) are oriented above the at least one filling opening (56) of the battery cells (54). [8] Degassing device (58) according to claims 5 to 7, characterized by , that the pipe sections (60) can be attached linearly, such that the closures (82) on the circumference (88) of the pipe sections (60) close the filling opening (56) of the number of battery cells (54) arranged on the workpiece carrier (50) and connect to the extraction system (70). [9] Degassing device (58) according to claims 5 to 8, characterized bythat it is attached to a top side (52) of the workpiece carrier (50) by means of an eccentric quick-release fastener or by means of a lever mechanism or by means of a screw connection. [10] Use of the method according to claims 1 to 4 for the production of battery cells (54). [11] Use of the degassing device (58) according to claims 5 to 9 for the manufacture of battery cells (54).

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