Core shaping system and method

Abstract

This application relates to the field of battery technology and discloses a core forming system and method. The core forming system includes a stretching device, a rolling device, and a hot pressing device. The stretching device is located upstream of the rolling device or at the same station as the rolling device. The rolling device includes a rolling platform, a roller, and a rolling traction mechanism. The rolling traction mechanism is connected to the roller and drives the roller to move to roll the core. The hot pressing device is located downstream of the rolling device. The stretching, rolling, and hot pressing devices realize the stretching, rolling, and hot pressing of the core. The core can be stretched and shaped before hot pressing and shaping after winding, which can effectively solve the problems of stress release in the electrode sheets and separators and / or the problem of free movement of the separator in the core, avoiding subsequent abnormalities such as wrinkles in the electrode sheets or separators, core deformation, or displacement.

Description

Technical Field

[0001] This application relates to the field of battery manufacturing technology, and in particular to a core shaping system and method. Background Technology

[0002] In lithium battery production, the main methods for manufacturing cores are winding and stacking. The winding method involves using a winding needle to wind the positive electrode sheet, separator, and negative electrode sheet into a basic core. In current manufacturing processes, after the positive and negative electrode sheets and separator are wound, the core is directly transferred to a hot press for hot pressing and shaping. However, after the core is unwound from the winding needle, the electrode sheets and separator experience stress release and / or are in a free-moving state, making them prone to wrinkling, deformation, or displacement. This is especially likely to occur near the corners of the core and the first fold of the innermost electrode, leading to electrode deformation and overall core deformation. This can cause battery interface performance failure, and even short circuits due to direct contact between the positive and negative electrodes, resulting in battery safety performance failure. Summary of the Invention

[0003] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a core shaping system and method that can effectively solve the problems of cell electrode / separator wrinkling, core deformation, and electrode displacement.

[0004] The core forming system according to an embodiment of this application includes a stretching device, a rolling device, and a hot pressing device, wherein: the stretching device is located upstream of the rolling device or at the same station as the rolling device, and the stretching device is used to stretch the core radially along the cylindrical core; the rolling device includes a rolling platform, a roller, and a rolling traction mechanism, the rolling platform is provided with a first plane for bearing the core stretched by the stretching device, and the rolling traction mechanism is connected to the roller and drives the roller to move in a direction parallel to the first plane to roll the stretched core; the hot pressing device is located downstream of the rolling device and is used to receive the core rolled by the rolling device and perform hot pressing.

[0005] The core shaping system of this application embodiment has at least the following beneficial effects: the core is stretched, rolled and hot-pressed by a stretching device, a rolling device and a hot-pressing device, and can be stretched and shaped first and then rolled before hot-pressing and shaping after the core is wound. This can effectively solve the problems of stress release in the electrode and separator in the core and / or the problem of free movement of the separator, avoid subsequent abnormalities such as wrinkles in the electrode or separator, core deformation or displacement, improve battery interface performance and safety performance failure, and improve cell quality.

[0006] According to some embodiments of this application, the stretching device includes a stretching traction mechanism and two support members. The stretching traction mechanism is connected to at least one of the support members and is capable of moving the two support members apart or toward each other along the rolling direction of the roller.

[0007] According to some embodiments of this application, the tensioning device further includes an installation platform and a limiting member, as well as two tensioning traction mechanisms. The tensioning traction mechanisms are movably connected to the installation platform, and each tensioning traction mechanism is connected to the support member. The limiting member is connected to the installation platform and is located on the side opposite to each other of the tensioning traction mechanisms, for supporting the tensioning traction mechanisms.

[0008] According to some embodiments of this application, the support member has a long rod-shaped structure, and the opposite sides of the two support members are provided with arc surfaces.

[0009] According to some embodiments of this application, the support member has an internal airflow channel, and a plurality of air outlets are provided on the opposite side of the support member. The air outlets are radially connected to the airflow channel, and the airflow channel is adapted to connect to an air source.

[0010] According to some embodiments of this application, the roller pressing device includes two rollers and two roller pressing traction mechanisms. Each roller is connected to one roller pressing traction mechanism. The roller pressing traction mechanism can adjust the stroke of the roller. The stroke includes a first stroke in which the roller moves in a direction parallel to the roller pressing platform and a second stroke in which the roller moves in a direction perpendicular to the roller pressing platform.

[0011] According to some embodiments of this application, the hot pressing device includes a heating mechanism, a first pressure plate, a second pressure plate, and a pressure plate driving mechanism. The heating mechanism is used to heat at least one of the first pressure plate and the second pressure plate. The first pressure plate and the second pressure plate are arranged facing each other. The first pressure plate is used to carry the core. The pressure plate driving mechanism is connected to and drives the second pressure plate to move between a first position and a second position to press the core. When the second pressure plate is in the first position, there is a minimum distance L between the first pressure plate and the second pressure plate.

[0012] According to some embodiments of this application, the hot pressing device further includes a limiting mechanism connected to the pressure plate driving mechanism, the limiting mechanism being used to limit the stroke of the pressure plate driving mechanism in driving the second pressure plate.

[0013] According to some embodiments of this application, a pair of shaping molds are respectively connected to the sides of the first pressure plate and the second pressure plate facing each other, the two pairs of shaping molds are aligned with each other, the shaping mold on the first pressure plate protrudes from the first pressure plate by a height of H1, the shaping mold on the second pressure plate protrudes from the second pressure plate by a height of H2, wherein H1+H2≤L.

[0014] According to some embodiments of this application, the shaping mold is provided with a shaping surface, the shaping surface is an arc surface, and the shaping surfaces of a pair of shaping molds face each other and can be enclosed to form a semi-circular arc surface.

[0015] The core shaping method provided in this application includes the following steps:

[0016] Stretching: The cylindrical core after being released from the winding needle is stretched radially to a set stroke, and the cylindrical core is stretched into a core having a width direction along the stretching direction.

[0017] Rolling: Rolling the core along the width direction of the stretched core;

[0018] Hot pressing: The core after roll pressing is hot pressed to shape it.

[0019] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of a core shaping system according to an embodiment of this application;

[0021] Figure 2 This is a schematic diagram of the tensioning device in the embodiments of this application;

[0022] Figure 3 This is a schematic diagram of the state of the stretching device when it is used to stretch the core in the embodiments of this application;

[0023] Figure 4 This is a schematic diagram of the roller pressing device in the embodiments of this application;

[0024] Figure 5 This is a schematic diagram of a roller pressing a core under tension.

[0025] Figure 6 This is a schematic diagram of the hot pressing device in the embodiments of this application;

[0026] Figure 7 This is a schematic diagram of a shaping mold in a hot pressing device.

[0027] Figure label:

[0028] Tensioning device 100, tensioning traction mechanism 101, support 102, mounting platform 103, limiting component 104, arc surface 105, air outlet 106.

[0029] Roller pressing device 200, roller pressing platform 201, roller 202, vertical traction mechanism 203, horizontal traction mechanism 204;

[0030] Hot pressing device 300, heating mechanism 301, first pressure plate 302, second pressure plate 303, shaping mold 304, shaping surface 305, pressure plate driving mechanism 306, limiting mechanism 307;

[0031] Conveyor belt 400, core 500, side 501. Detailed Implementation

[0032] The following will clearly and completely describe the concept and technical effects of this application in conjunction with embodiments, so as to fully understand the purpose, features and effects of this application. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are all within the scope of protection of this application.

[0033] In the description of the embodiments of this application, if directional descriptions are involved, such as "up", "down", "front", "back", "left", "right" etc., indicating the directional or positional relationship based on the directional or positional relationship shown in the drawings, it is only for the convenience of describing this application and simplifying the description, and is not intended to indicate or imply that the device or device referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0034] In the description of the embodiments of this application, if a feature is referred to as "setting," "fixing," "connecting," or "installing" on another feature, it can be directly set, fixed, or connected to the other feature, or it can be indirectly set, fixed, connected, or installed on the other feature. In the description of the embodiments of this application, if "several" is involved, it means one or more; if "multiple" is involved, it means two or more; if "greater than," "less than," or "exceeds," it should be understood as excluding the stated number; if "above," "below," or "within," it should be understood as including the stated number. If "first" or "second" is involved, it should be understood as used to distinguish technical features, and not as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the order of the indicated technical features.

[0035] In the current manufacturing process, after the positive and negative electrode sheets and separator are wound, the core is directly transferred to a hot press for hot pressing and shaping. This manufacturing process easily leads to wrinkling and deformation of the electrode sheets / separator and free displacement of the electrode sheets, especially near the corners of the core (between the large plane of the core and the arc of the corner, where there is a height difference and uneven stress on the electrode sheets) and the first fold of the innermost electrode sheet. Therefore, this manufacturing process restricts the performance of the battery cell, and the deformation problem is particularly serious after winding thicker battery cells.

[0036] This application provides a core forming system, including a stretching device, a rolling device, and a hot pressing device, which can effectively solve the problems of cell electrode / separator wrinkling, core deformation, and electrode displacement, thereby improving the cell interface performance and safety performance. The embodiments of this application are described below with reference to the accompanying drawings:

[0037] Figure 1 This is a schematic diagram of the structure of a core shaping system according to an embodiment of this application, with reference to... Figures 1 to 3 The core shaping system of this application includes a stretching device 100, a rolling device 200, and a hot pressing device 300. The stretching device 100 is used to stretch and pull the core 500 after winding, stretching the core 500 from the wound circular or elliptical cylindrical shape along the radial direction by a set distance to form a relatively flat structure, thereby achieving the initial shaping of the core 500 to facilitate subsequent rolling. The rolling device 200 is used to roll and shape the stretched and shaped core 500. The hot pressing device 300 is used to hot press and shape the rolled core 500.

[0038] In this embodiment, after the core 500 is formed by winding, the core 500 has a cylindrical structure and leaves a central hole in the middle left by the removal of the winding needle.

[0039] The roller pressing device 200 includes a roller pressing platform 201, a roller bar 202, and a roller pressing traction mechanism. The roller pressing platform 201 is provided with a first plane, which is used to support the core 500 stretched by the stretching device 100. The roller bar 202 is parallel to the roller pressing platform 201. The roller pressing traction mechanism is connected to the roller bar 202 and drives the roller bar 202 to move in a direction parallel to the first plane to press the stretched core 500.

[0040] The stretching device 100 can be located upstream of the rolling device 200, or the stretching device 100 and the rolling device 200 can be located at the same station. Here, "station" refers to each position occupied by the workpiece (or assembly unit) and the movable part of the fixture or equipment relative to the fixed part of the equipment after the workpiece is clamped once, in order to complete a certain process. "Process" refers to a portion of the technological steps continuously completed by the workpiece being processed or assembled at a station. In the embodiments of this application, the core 500 can complete the stretching process via the stretching device 100 and the rolling process via the rolling device 200. The stretching device 100 can be located upstream of the rolling device 200, so that the core 500 occupies different positions in the fixed part of the core forming system (e.g., frame or ground) during the stretching and rolling processes. After stretching, the core 500 can be transferred to the rolling platform 201 for rolling. In other embodiments, the stretching device 100 can also be located at the same station as the rolling device 200, so that the core 500 occupies the same position in the fixed part of the core forming system (e.g., frame or ground) during the stretching and rolling processes. For example, the core 500 can be stretched and rolled sequentially above the rolling platform 201, and can be rolled without transfer after stretching.

[0041] The hot pressing device 300 is located downstream of the rolling device 200 and is used to receive the core 500 after it has been rolled by the rolling device 200 and perform hot pressing. Thus, the core 500 is stretched, rolled, and hot pressed by the stretching device 100, the rolling device 200, and the hot pressing device 300. After the core 500 is wound, it can be stretched and shaped first, stretching the core 500 from the wound circular or elliptical cylindrical shape along the radial direction by a set distance, forming a certain width in the stretching direction, and forming two opposing large surfaces in the thickness direction perpendicular to the stretching direction. This stretches the core 500 into a relatively flat structure, achieving the initial shaping of the core 500. Then, it is rolled and hot pressed to fix the shape. This can effectively solve the problems of stress release during winding of the electrode and separator in the core 500 and / or the problem of free movement of the separator, avoiding subsequent abnormalities such as wrinkles of the electrode or separator, deformation or displacement of the core 500.

[0042] Among them, reference Figure 2In some embodiments, the stretching device 100 includes a stretching traction mechanism 101 and two support members 102. The support members 102 are adapted to be inserted into the axial hole of the core 500. The stretching traction mechanism 101 is connected to at least one support member 102 and can make the two support members 102 move apart or toward each other along the rolling direction of the roller 202. Thus, by driving the movement of the support members 102 to stretch and pull the core 500, the winding stress of the electrode and the separator can be released while the free displacement of the electrode can be avoided by stretching and pulling, thus achieving the initial shaping of the core 500. Then, the core is rolled by the rolling device 200, which effectively eliminates the problem of wrinkling and deformation of the electrode / separator.

[0043] In some embodiments, the stretching device 100 further includes a mounting platform 103 and a limiting member 104. The limiting member 104 is connected to the mounting platform 103 and can limit the maximum distance between the two support members 102 by limiting the stretching traction mechanism 101. For example, the stretching device 100 may include two stretching traction mechanisms 101, which are movably connected to the mounting platform 103. Each stretching traction mechanism 101 is connected to a support member 102 and drives the support member 102 to move, thereby stretching the core 500. The limiting member 104 includes two members, which are respectively connected to the mounting platform 103 and located on the opposite side of the stretching traction mechanisms 101. They are used to hold the stretching traction mechanism 101 at a set position to limit the maximum stroke of the two stretching traction mechanisms 101 moving in opposite directions, thereby limiting the maximum distance between the two support members 102 and avoiding damage to the core 500.

[0044] Alternatively, the tensioning device 100 may include a tensioning traction mechanism 101 connected to one of the support members 102 and used to drive the support member 102 to move relative to the other support member 102. The tensioning device 100 may also include a limiting member 104 connected to the mounting platform 103 and located on the side of the tensioning traction mechanism 101 away from the other support member 102. The limiting member 104 is used to hold the tensioning traction mechanism 101 at a set position to limit its maximum stroke away from the other support member 102, thereby limiting the maximum distance between the two support members 102 and avoiding damage to the core 500.

[0045] The tensioning and traction mechanism 101 can be a linear motion mechanism such as a linear motor or cylinder, having a base and an output section. It is mounted on the mounting platform 103 via the base, and the movement of the output section drives the movement of the corresponding support member 102. The limiting member 104 can be a block-shaped or columnar protrusion fixedly connected to the mounting platform 103 as described above, used to hold the output section of the tensioning and traction mechanism 101, achieving mechanical limiting. Alternatively, the tensioning and traction mechanism 101 can also limit the maximum spacing of the support members 102 by presetting its own stroke, with the limiting member 104 serving as a mechanical limit to improve the mechanism's safety. The power element in the tensioning and traction mechanism 101 can be a servo motor, which has high control precision, thereby improving the control precision of the stroke of the corresponding support member 102. This effectively avoids damage to the core 500 due to excessive tension stroke of the support member 102, and also avoids poor shaping of the core 500 due to insufficient tension stroke of the support member 102, which would affect subsequent rolling.

[0046] In some embodiments, the support member 102 has a long rod-like structure, suitable for insertion into the innermost coil of the core 500 along the axial direction. The tensioning and traction mechanism 101 is connected to the support member 102 via a connector, thereby driving the support member 102 to move apart, thus stretching and tractioning the wound core 500 radially. The opposing sides of the two support members 102 are provided with arc surfaces 105. The arc surfaces 105 can be provided on the support members 102 in various ways. For example, the support member 102 can be a rod-like structure with a circular or elliptical cross-section, thus having an arc surface 105 on its outer surface; or, the support member 102 can be a rod-like structure with an approximately polygonal cross-section, with rounded corners, thus forming arc surfaces 105 at the corners. This reduces damage to the electrode or separator membrane caused by the support member 102 during the stretching process. The axial ends of the support member 102 can also be rounded to reduce damage to the electrode or separator membrane during axial movement.

[0047] The support member 102 can adopt a relatively flat rod-shaped structure, that is, the dimension of the support member 102 along the stretching direction is larger than the dimension perpendicular to the stretching direction. The flat rod-shaped structure can reduce the contact area between the side of the support member 102 along the stretching direction and the inner ring of the core 500 while ensuring the strength of the support member 102. This reduces the gap between the electrodes at the corner of the inner ring of the core 500, reduces the lithium ion transmission distance, and thus mitigates lithium plating caused by the long lithium ion transmission distance.

[0048] In addition, the support 102 may be made of a wear-resistant material or the outer surface of the support 102 may be provided with a protective layer made of a wear-resistant material, such as a polymer plastic or Teflon material, which can effectively reduce the wear of the support 102 and reduce replacement costs.

[0049] In some embodiments, the support member 102 is provided with an airflow channel inside, and a plurality of air outlets 106 are provided on the opposite side of the support member 102. The air outlets 106 are radially connected to the airflow channel. The airflow channel is suitable for connecting to an air source. Therefore, when the support member 102 is retracted, the air source is connected and air is blown through the air outlets 106, which can effectively reduce the adsorption of the support member 102 on the electrode or separator, ensure that the support member 102 is smoothly detached from the core 500, and reduce the probability of wrinkles or damage to the electrode or separator.

[0050] In some embodiments, the rolling device 200 includes two rollers 202 and two rolling traction mechanisms. The rollers 202 are used to roll the core 500. Each roller 202 is connected to a rolling traction mechanism. The rollers 202 are parallel to the rolling platform 201 to ensure uniform force on the core 500. The rolling traction mechanism can adjust the stroke of the rollers 202, thereby rolling the stretched core 500. The stroke of the rollers 202 includes a first stroke in which the rollers 202 move in a direction parallel to the rolling platform 201, and a second stroke in which the rollers 202 move in a direction perpendicular to the rolling platform 201. Therefore, the position of the roller 202 relative to the core 500 and the relative position between the two rollers 202 can be adjusted by the first stroke, and the position of the roller 202 pressing down toward the core 500 can be adjusted by the second stroke, thereby determining the thickness of the core 500 being rolled. Then, by adjusting the first stroke, the roller 202 rolls the core 500 in a direction parallel to the rolling platform 201. The first stroke and the second stroke can be reasonably adjusted according to the required stretching width and rolling thickness of the core 500.

[0051] The roller pressing traction mechanism may include a vertical traction mechanism 203 and a horizontal traction mechanism 204. The vertical traction mechanism 203 drives the roller 202 to move in a direction perpendicular to the roller pressing platform 201, and the horizontal traction mechanism 204 drives the roller 202 to move in a direction parallel to the roller pressing platform 201. The start and stop of the vertical traction mechanism 203 adjusts the second stroke of the roller 202 to prevent damage caused by overpressure on the core 500. The start and stop of the horizontal traction mechanism 204 adjusts the first stroke of the roller 202 to maintain a set distance between the two rollers 202 to prevent collision damage. Both the vertical traction mechanism 203 and the horizontal traction mechanism 204 can be servo motors, which have high control precision, thereby improving the corresponding positional accuracy of the roller 202.

[0052] In the configuration where the stretching device 100 is positioned upstream of the rolling device 200, the stretching device 100 may be equipped with a transfer mechanism connected to the stretching traction mechanism 101. This transfer mechanism moves the stretching traction mechanism 101, along with the support member 102, above the rolling platform 201, thereby maintaining the stretching traction on the core 500 before rolling. Thus, during rolling, the support member 102 can be disengaged from the core 500 after the roller 202 has moved to a set position parallel to the rolling platform 201. This allows the core 500 to remain stretched during the first half of the rolling process. After the support member 102 disengages from the core 500, the roller 202 continues rolling to the edge of the core 500. This significantly improves the wrinkling deformation of the inner ring of the core 500 electrode and the positioning of the electrode, and also facilitates the shaping of the corners of the core 500. This rolling process can be controlled by starting and stopping the rolling traction mechanism. The transfer mechanism can be implemented using commonly used mechanisms for transferring items in mechanized equipment, such as linear motors, multi-axis robotic arms, etc.

[0053] After the core 500 has completed the stretching and rolling shaping process, the hot pressing device 300 can further apply force to the core 500 under high temperature and high pressure conditions, so that the core 500 is shaped, preventing the core 500 from deforming and the electrode from shifting, and can also solidify the bonding effect between the electrode and the separator. In some embodiments of the core forming system, the hot pressing device 300 includes a heating mechanism 301, a first pressure plate 302, a second pressure plate 303, and a pressure plate driving mechanism 306. The heating mechanism 301 is used to heat at least one of the first pressure plate 302 and the second pressure plate 303. The first pressure plate 302 and the second pressure plate 303 are arranged facing each other. The first pressure plate 302 is used to carry the core 500. The pressure plate driving mechanism 306 is connected to and drives the second pressure plate 303 to move between a first position and a second position to press the core 500. When the second pressure plate 303 is in the first position, there is a minimum distance L between the first pressure plate 302 and the second pressure plate 303, and the core 500 is hot-pressed between the first pressure plate 302 and the second pressure plate 303.

[0054] The method for shaping the core 500 using the core shaping system of the above embodiment may include the following steps:

[0055] The core 500, after being detached from the winding needle, is stretched radially by the stretching device 100 for a set stroke to form a core 500 with a set width in the stretching direction and a set thickness perpendicular to the stretching direction; the stretching traction mechanism 101 drives two support members 102 to extend into the inner circle of the core 500, and drives at least one support member 102 to move radially along the core 500 for a set stroke to increase the distance between the two support members 102 and stretch the core 500 radially.

[0056] Rolling is performed by placing the stretched core 500 on a rolling platform 201, with the width direction of the core 500 parallel to the rolling platform 201. The rolling traction mechanism adjusts the movement of the rollers 202 to achieve rolling of the stretched core 500. The support member 102 and the core 500 can be placed together on the rolling platform 201. With the support member 102 inside the core 500 and moved to its maximum distance from it, the two rollers 202 roll the core 500 from the middle of its width direction towards the side 501. When the rollers 202 reach a set position, the two support members 102 can be pulled out first, and the rollers 202 continue rolling towards the edge of the core 500's width direction. The surface detached from the core; preferably, the width of the core 500 is L1, and along the width direction, the roller 202 moves to a distance of L2 between itself and the edge of the core 500, satisfying: 0.1≤L2 / L1≤0.3, when the two support members 102 are pulled out, the roller 202 continues to roll along the edge of the core 500 in the width direction, to avoid the support members 101 and the roller 202 jointly squeezing the inner layer of the core 500 and causing wrinkles; more preferably, before the two support members 102 are pulled out, the two support members 102 move towards each other by a set distance L3, preferably, L3 satisfies: 0.05≤L3 / L1≤0.3, to avoid the movement of the inner layer of the core 500 caused by the support members 102 being pulled out, which would cause wrinkles.

[0057] Hot pressing: The heating mechanism 301 heats the first pressure plate 302 and / or the second pressure plate 303, transferring the rolled core 500 onto the first pressure plate 302 of the hot pressing device 300. The second pressure plate 303 moves toward the first pressure plate 302 along the thickness direction of the core 500 to a first position, so as to hot press the rolled core 500 between the first pressure plate 302 and the second pressure plate 303, thereby achieving hot pressing and shaping of the core 500.

[0058] In practice, the support member 102 can be detached from the core 500 before the stretched core 500 is fed into the rolling platform 201 of the rolling device 200 for rolling. For example, refer to Figure 1 In some embodiments, the shaping system may include a conveyor belt 400, a stretching device 100, a rolling device 200, and a hot pressing device 300 arranged along the conveyor belt 400. The conveyor belt 400 is used to sequentially transport the core 500 to the stretching device 100, the rolling device 200, and the hot pressing device 300. The rolling platform 201 and the first pressure plate 302 are located below the conveyor belt 400, the roller 202 is located above the conveyor belt 400 corresponding to the rolling platform 201, and the second pressure plate 303 is located above the conveyor belt 400 corresponding to the position of the first pressure plate 302. The conveyor belt 400 can transfer the core 500 above the rolling platform 201 or the hot pressing platform and hold it for a set time for rolling or hot pressing.

[0059] In some embodiments, the hot pressing device 300 further includes a limiting mechanism 307, which can be connected to the pressure plate driving mechanism 306. The limiting mechanism 307 is used to limit the stroke of the pressure plate driving mechanism 306 driving the second pressure plate 303, thereby controlling the minimum distance between the first pressure plate 302 and the second pressure plate 303 required for hot pressing, so as to determine the pressure applied to the core 500 and effectively prevent the core 500 from being damaged by overpressure. In other embodiments, the limiting mechanism 307 can also be disposed between the first pressure plate 302 and the second pressure plate 303, connected to the first pressure plate 302 or the second pressure plate 303, and can abut against the first pressure plate 302 and the second pressure plate 303 when the first pressure plate 302 and the second pressure plate 303 move towards each other to the minimum distance, so as to achieve mechanical limiting and effectively avoid overpressure of the core 500.

[0060] Due to the unique structure of the core 500, there are two corners on the edge of the core 500 in the width direction. Before shaping, the electrode / separator of the core 500 is prone to wrinkling and deformation, and the electrode is prone to free displacement. This is especially likely to occur near the corners of the bare cell (between the large plane of the core 500 and the arc transition area of ​​the corner, where there is a height difference and uneven stress on the electrode) and the first fold of the innermost electrode. Therefore, during the later use of the cell, the corners usually fail first, showing abnormalities such as black spots and lithium plating, thus affecting the service life of the cell. In some embodiments, a pair of shaping molds 304 are respectively connected to the side of the first pressure plate 302 and the second pressure plate 303 facing each other, and the two pairs of shaping molds 304 are aligned with each other. The shaping mold 304 on the first pressure plate 302 protrudes from the first pressure plate 302 by a height of H1, and the shaping mold 304 on the second pressure plate 303 protrudes from the second pressure plate 303 by a height of H2, where H1 + H2 ≤ L. This avoids interference between the shaping mold 304 and the movement of the second pressure plate 303 before it reaches the first position, ensuring that the core 500 is fully heat-pressed and that the force is evenly distributed across all parts. The two pairs of shaping molds 304 are used to hold the side corners of the core 500 in the width direction during the heat-pressing process. Therefore, the corners of the core 500 can also be stressed during heat pressing, achieving a comprehensive heat-pressing and shaping effect. This reduces the probability of the aforementioned problems occurring at the corners during later use of the battery cell, thereby effectively improving the quality of the battery cell.

[0061] After the core 500 is stretched and rolled, an arc-shaped outer surface is generally formed at the corner of the edge in the width direction. In order to optimize the hot pressing effect at the corner, in some embodiments, the shaping mold 304 is provided with a shaping surface 305. The shaping surface 305 is an arc-shaped surface, and the shaping surfaces 305 in a pair of shaping molds 304 face each other and can be enclosed to form a semi-circular arc surface 105, which matches the shape of the corner formed after the core 500 is rolled. Thus, the corner can be heated and stressed evenly during the hot pressing process, thereby improving the shaping effect of the core 500.

[0062] The core shaping system of this application embodiment realizes the sequential stretching and shaping, roll forming and hot pressing of the core 500 through the traction device, the rolling device 200 and the hot pressing device 300, which solves the problems of cell electrode / separator wrinkles, core 500 deformation and electrode displacement, thereby improving the cell interface performance and safety performance and improving the cell quality.

[0063] The embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application. Furthermore, unless otherwise specified, the embodiments and features described in the embodiments of this application can be combined with each other.

Claims

1. A core shaping system, characterized by, The device comprises a stretching device (100), a rolling device (200) and a hot-pressing device (300), wherein: The stretching device (100) is arranged at an upstream station of the rolling device (200) or at the same station as the rolling device (200), and is used to stretch a cylindrical core (500) in the radial direction of the core (500); The rolling device (200) comprises a rolling platform (201), a roller (202) and a rolling traction mechanism, the rolling platform (201) is provided with a first plane for carrying the core (500) stretched by the stretching device (100), the rolling traction mechanism is connected to the roller (202) and drives the roller (202) to move in a direction parallel to the first plane to roll the stretched core (500); wherein the stretching device (100) comprises a stretching traction mechanism (101) and two support members (102), the stretching traction mechanism (101) is connected to at least one of the support members (102) and can make the two support members (102) move away from or towards each other in the rolling direction of the roller (202); the support members (102) are placed on the rolling platform (201) together with the core (500), and after the roller (202) moves to a set position in a direction parallel to the first plane, the support members (102) are separated from the core (500); The hot-pressing device (300) is arranged at a downstream station of the rolling device and is used to receive the core (500) rolled by the rolling device (200) and perform hot-pressing.

2. The core shaping system of claim 1, wherein The stretching device (100) further comprises a mounting platform (103) and a limiting member (104), and two stretching traction mechanisms (101), the stretching traction mechanisms (101) are movably connected to the mounting platform (103), each stretching traction mechanism (101) is connected to the support member (102), and the limiting member (104) is connected to the mounting platform (103) and located on a side away from the stretching traction mechanisms (101) to abut against the stretching traction mechanisms (101).

3. The core shaping system of claim 1, wherein The support members (102) have a long rod structure, and the sides away from each other of the two support members (102) are provided with arc surfaces (105).

4. The core shaping system of claim 1, wherein The support members (102) are provided with airflow channels inside and a plurality of air outlets (106) on the sides away from each other, the air outlets (106) are connected to the airflow channels in the radial direction of the airflow channels, and the airflow channels are adapted to be connected to a gas source.

5. The core sizing system of claim 1, wherein The roller pressing device (200) comprises two roller rods (202) and two roller pressing traction mechanisms, each roller rod (202) is connected to one roller pressing traction mechanism, the roller pressing traction mechanism can adjust the stroke of the roller rod (202), the stroke comprises a first stroke in which the roller rod (202) moves in a direction parallel to the roller pressing platform (201) and a second stroke in which the roller rod (202) moves in a direction perpendicular to the roller pressing platform (201).

6. The core sizing system of claim 1, wherein The hot pressing device (300) comprises a heating mechanism (301), a first pressing plate (302), a second pressing plate (303) and a pressing plate driving mechanism (306), the heating mechanism (301) is used for heating at least one of the first pressing plate (302) and the second pressing plate (303), the first pressing plate (302) and the second pressing plate (303) are oppositely arranged, the first pressing plate (302) is used for carrying the roll core (500), the pressing plate driving mechanism (306) is connected to and drives the second pressing plate (303) to move between a first position and a second position to press the roll core (500), when the second pressing plate (303) is located at the first position, the first pressing plate (302) and the second pressing plate (303) have a minimum distance L.

7. The core shaping system of claim 6, wherein The hot pressing device (300) further comprises a limiting mechanism (307), the limiting mechanism (307) is connected to the pressing plate driving mechanism (306), and the limiting mechanism (307) is used for limiting the stroke of the pressing plate driving mechanism (306) for driving the second pressing plate (303) to move.

8. The core shaping system of claim 6, wherein The first pressing plate (302) and the second pressing plate (303) are respectively connected to a pair of shaping molds (304) on the side facing each other, the two pairs of shaping molds (304) are aligned with each other, the height of the shaping mold (304) on the first pressing plate (302) protruding from the first pressing plate (302) is H1, and the height of the shaping mold (304) on the second pressing plate (303) protruding from the second pressing plate (303) is H2, wherein H1+H2≤L.

9. The core shaping system of claim 8, wherein The shaping mold (304) is provided with a shaping surface (305), the shaping surface (305) is an arc surface, and the shaping surfaces (305) in one pair of shaping molds (304) face each other and can be combined to form a semicircular arc surface.

10. A method for shaping a core, characterized in that, The method comprises the following steps: Stretching: two supporting members (102) are used to stretch the cylindrical roll core after the roll needle to a set stroke in the radial direction, so that the cylindrical roll core is stretched into the roll core with a set width in the stretching direction; Rolling: the support (102) and the roll core are placed on a rolling platform (201), the roll core is rolled by a roller (202) along the width direction of the stretched roll core, and the support (102) is separated from the roll core after the roller (202) moves to a set position along a direction parallel to the rolling platform (201), and the roller (202) continues to roll to the edge of the roll core after the support (102) is separated from the roll core; Hot pressing: the roll core after rolling is hot pressed and shaped.

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