Cutting die suitable for pole piece slitting, equipment suitable for pole piece slitting and pole piece slitting method

Abstract

The invention relates to the technical field of batteries, in particular to a cutting die suitable for pole piece slitting, equipment suitable for pole piece slitting and a pole piece slitting method. The cutting die comprises a base plate, and the base plate is provided with at least one contour cutting part, a cutting edge of which has a contour matched with a to-be-cut waste area between the two adjacent pole pieces, and a cutting edge of which has a cutting edge matched with the to-be-cut waste area between the two adjacent pole pieces. The cutting edge of the linear cutting part is linear and extends in the width direction of the base plate, the linear cutting part and the contour cutting parts are arranged in a mutually separated mode, and the orthographic projection of the end, close to the contour cutting parts, of the cutting edge of the linear cutting part on the base plate is larger than the orthographic projection of the end, close to the contour cutting parts, of the linear cutting part on the base plate. And the orthographic projection of the cutting edge contour falling into the contour cutting part on the substrate extends in the direction of the linear cutting part to form an area.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium ion batteries, in particular to a knife die suitable for cutting of an electrode sheet, an equipment suitable for cutting of an electrode sheet and a method for cutting of an electrode sheet. BACKGROUND

[0002] In the process of manufacturing lithium batteries, the forming of the electrode sheet is one of the key steps. Currently, the common electrode sheet die-cutting processes in the industry mainly include three types: adhesive plate knife die-cutting, hardware die-cutting and laser die-cutting.

[0003] Among them, the adhesive plate knife die-cutting occupies an irreplaceable position in the small-batch and multi-variety battery production scenarios due to its low manufacturing cost, short cycle, and convenient changeover. Referring to FIG. 1, a traditional adhesive plate knife die is composed of a PVC adhesive plate and a white steel blade embedded on the surface of the adhesive plate. The white steel blade forms a closed shape consistent with the outer contour shape of an electrode sheet. Referring to FIG. 2, the contour forming of a single electrode sheet (including the main body part and the tab part) can be completed by one stamping action, which belongs to a typical "one-time die-cutting forming" process. Figure 1 Figure 2 However, the present application found that this process has inherent technical defects during the research of the present application: in order to ensure the die-cutting size accuracy (which can only be controlled within ±0.2mm) and adapt to the fluctuations of the material flatness, die-cutting machine traction accuracy, etc., a certain safety distance must be reserved between adjacent electrode sheets. This reserved area becomes waste after die-cutting. The existence of waste directly leads to the following problems: Significant waste of valuable raw materials such as positive and negative electrode foils, low material utilization, and high production cost.

[0004] Waste materials are prone to produce metal dust (powder) during die-cutting and waste removal. These dusts may adhere to the surface of the electrode sheet, causing internal short circuit in the subsequent battery assembly, which seriously threatens the safety and service life of the battery.

[0005] Although the hardware die-cutting and laser die-cutting technologies can achieve "nest cutting" without or with little waste, thereby solving the above problems, their equipment purchase cost is high, the mold making is complex and long, and the changeover flexibility is poor. For many small and medium-sized battery factories or research and development trial production stages, the economic efficiency is poor, and it is difficult to completely replace the adhesive plate knife die. SUMMARY

[0006] One of the purposes of the embodiments of the present application is to provide a knife die suitable for cutting of an electrode sheet, an equipment suitable for cutting of an electrode sheet and a method for cutting of an electrode sheet. The technical solution is beneficial to reduce the waste of electrode sheet cutting.

[0007] One of the purposes of the embodiments of the present application is to provide a knife die suitable for cutting of an electrode sheet, an equipment suitable for cutting of an electrode sheet and a method for cutting of an electrode sheet. The technical solution is beneficial to reduce the waste of electrode sheet cutting.

[0008] ​In a first aspect, the embodiments of the present application provide a die suitable for cutting of pole pieces, comprising a base plate, wherein the base plate is provided with: at least one profiled cutting portion, the cutting edge of which matches the profile of the waste area to be cut between two adjacent pole pieces; a linear cutting portion, the cutting edge of which is linear and extends along the width direction of the base plate, wherein the linear cutting portion is arranged separately from each profiled cutting portion, and the end of the cutting edge of the linear cutting portion close to each profiled cutting portion is projected onto the base plate within the area formed by the projection of the cutting edge profile of the profiled cutting portion along the direction of the linear cutting portion.

[0009] Optionally, a V-shaped or circular-arc-shaped protruding blade is arranged on the cutting edge of each profiled cutting portion, wherein the V-shaped or circular-arc-shaped protruding blade is arranged within the area formed by the projection of the cutting edge of the linear cutting portion onto the base plate.

[0010] Optionally, the included angle of the V-shaped protruding blade is in the range of 30° to 150°.

[0011] Optionally, two opposite profiled cutting portions are included, wherein the linear cutting portion is arranged on the same side of the two profiled cutting portions.

[0012] Optionally, the two ends of the projection of the cutting edge of the linear cutting portion onto the base plate are respectively projected onto the area formed by the projection of the cutting edge profile of the two profiled cutting portions along the direction of the linear cutting portion.

[0013] Optionally, the profiled cutting portion and / or the linear cutting portion is a white steel blade.

[0014] Optionally, the base plate is a PVC plate.

[0015] In a third aspect, the embodiments of the present application provide a device suitable for cutting of pole pieces, for cutting a continuous sheet-shaped base material into a plurality of independent pole pieces, wherein the device comprises: a unwinding device for unwinding the continuous sheet-shaped base material; a traction device for guiding the base material to move along a cutting path; the die according to any one of claims 1 to 7, which is arranged above the cutting path and the cutting edges of the profiled cutting portions and the linear cutting portion are directed towards the base material; and a driving device for driving the die to perform a die-cutting movement towards the base material.

[0016] Optionally, along the traction direction of the substrate, each of the contour cutting portions is located in front of the linear cutting portion.

[0017] Thirdly, embodiments of the present invention provide a method for cutting electrodes using any of the above-described die-cutting techniques suitable for electrode cutting.

[0018] As can be seen from the above, by applying the die-cutting structure of this embodiment, the first contour cutting part and the linear cutting part, which are separately set on the die, act on different areas between two adjacent electrodes, and combined with the traction motion of the slitting equipment, the electrode is slitted through multiple punching steps. Furthermore, using the scheme of this embodiment, there is no waste material between the main bodies of each pair of adjacent electrodes obtained by slitting, which helps to reduce waste loss in production and lower production costs. More importantly, the cutting path of the linear cutting part must overlap with the end of the path formed by the previous punching of the first contour cutting part, thereby cleanly separating the electrode and ensuring the integrity of the electrode contour. Attached Figure Description

[0019] The accompanying drawings, which are provided to further illustrate the invention and form part of this application, do not constitute an undue limitation of the invention.

[0020] Figure 1 A schematic diagram of the structure of an existing electrode sheet slitting die. Figure 2 For application Figure 1 The diagram shows the principle of electrode cutting using a rubber sheet die. Figure 3 This is a schematic diagram of the structure of a die for cutting electrode sheets according to Embodiment 1 of the present invention; Figure 4 For application Figure 3 The diagram shown illustrates the punching principle during the first punching cut when the die is used to cut the electrode sheet. Figure 5 For application Figure 3 The diagram shown illustrates the punching principle during the second punching process when the die is used to cut the electrode sheet. Figure 6 For application Figure 3 The diagram shown illustrates the punching principle during the third punching process when the die is used to cut the electrode sheet. Figure 7 For application Figure 3 The diagram shown illustrates the punching principle during the fourth punching step in electrode sheet slitting using a die-cutting mold. Figure 8 This is a schematic diagram of the structure of a die for cutting electrode sheets according to Embodiment 2 of the present invention; Figure 9 For application Figure 8The first punching principle diagram when the knife die shown is used to perform the first time of punching when the pole piece is slitting; Figure 10 For application Figure 8 The second punching principle diagram when the knife die shown is used to perform the second time of punching when the pole piece is slitting; Figure 11 For application Figure 8 The third punching principle diagram when the knife die shown is used to perform the third time of punching when the pole piece is slitting; Figure 12 For application Figure 8 The fourth punching principle diagram when the knife die shown is used to perform the fourth time of punching when the pole piece is slitting.

[0021] Reference signs: 11: substrate; 12: first profile cutout; 13: linear cut-off part; 14: second profile cutout; 15: V-shaped outer protruding blade; 21: current collector exposed area; 29: polar active material layer; 22: first tab part; 23: first pole piece; 24: second tab part; 25: second pole piece; 26: third tab part; 27: third pole piece; 28: fourth tab part. DETAILED DESCRIPTION

[0022] The present application will be described in detail below with reference to the accompanying drawings and specific embodiments, which are intended to explain the present application, but not as a limitation of the present application.

[0023] Examples of embodiments of the present application are described in detail below, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout the drawings.

[0024] The embodiments described below with reference to the accompanying drawings of the present specification are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application. In the description of the present application, it is understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0025] In addition, the terms "first", "second", etc. are used only for descriptive purposes and should not be construed as indicating or implying relative importance or an indicated number of the technical features indicated. Therefore, the features defined as "first", "second", etc. can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.

[0026] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above-mentioned terms in the present application can be understood according to the specific circumstances.

[0027] Embodiment one: knife die suitable for cutting of pole piece

[0028] Reference Figures 3 to 7 The present embodiment provides a knife die suitable for cutting of pole piece, which is different from the traditional one-time punching forming knife die in structure design.

[0029] The knife die of the present embodiment is used to cut the continuous sheet-shaped base material in roll form into independent pole pieces, each pole piece including a main body portion coated with a layer of polar active material 29 on the surface, and a current collector exposed tab portion.

[0030] The knife die includes a base plate 11, at least one profile cutout portion (referred to as first profile cutout portion 12) and a linear cutting portion 13 are arranged on the base plate 11.

[0031] The edge shape of each first profile cutout portion 12 matches the profile of the waste area to be cut between the adjacent two pole pieces. The edge of the linear cutting portion 13 is linear, and is arranged separately from each first profile cutout portion 12.

[0032] This structure divides the punching action into two parts: the first profile cutout portion 12 at the end is responsible for cutting off the waste at the end of the pole piece (the end or bottom of the tab portion), and the linear cutting portion 13 is responsible for separating the pole pieces.

[0033] The end of the blade of the linear cutting portion 13 near the first profile cutting portion 12 falls within the region formed by the extension of the normal projection of the blade profile of the first profile cutting portion 12 on the substrate 11 along the direction of the linear cutting portion 13. The end of the blade of the linear cutting portion 13 is located inside the cutting track formed by the last time the first profile cutting portion 12 is punched. With this arrangement, the cutting path of the first profile cutting portion 12 is ensured to cover the end of the cutting path of the linear cutting portion 13 from the structure of the die, step punching is achieved, and burrs or scraps are avoided.

[0034] Taking the jelly-roll polar piece with the tab part located at the width end of the polar piece as an example, a certain width of the current collector bare area 21 (i.e., the area where both surfaces are not coated with the polar active material layer 29) is reserved at the first length edge side of the jelly-roll polar piece, and the polar active material layer 29 is coated on both surfaces of the other areas of the polar piece. When the polar piece is slitting, the waste is cut off at the first length edge side of the jelly-roll polar piece to form the tab part of the polar piece, and the linear cutting portion 13 along the width edge of the jelly-roll polar piece cuts off the adjacent two polar pieces.

[0035] Taking the slitting of the polar piece with the above structure as an example, the die of the embodiment includes a first profile cutting portion 12 and a linear cutting portion 13.

[0036] After the slitting device is started, the jelly-roll polar piece moves along the traction direction, the blade profile of the first profile cutting portion 12 on the die is above the current collector bare area 21 at the first length edge side of the jelly-roll polar piece, the blade of the linear cutting portion 13 on the die is linear and extends along the width direction of the jelly-roll polar piece and is above the polar active material layer 29 coating area of the polar piece, and the end near the first profile cutting portion 12 is above the current collector bare area 21 at the first length edge side. It is assumed that the jelly-roll polar piece moves from back to front along the traction direction, the linear cutting portion 13 is in front of the first profile cutting portion 12, so that the jelly-roll polar piece passes through the first profile cutting portion 12 first and then passes through the linear cutting portion 13. The end of the normal projection of the linear cutting portion 13 near the current collector bare area 21 is located inside the current collector bare area 21 and does not exceed the first length edge of the jelly-roll polar piece, and the other end exceeds the main part of the polar piece being slitted.

[0037] At the punching station, when the first profile cutting portion 12 is punched for the first time, the waste at the end of the first polar piece 23 at the first length edge is cut off, and the profile line of the front end of the first tab part 22 of the first polar piece 23 is punched. At this time, the punching object below the blade of the linear cutting portion 13 in front is empty, and the main part of the first polar piece 23 is connected to the jelly-roll polar piece.

[0038] After the base material has advanced by one tab pitch in the pulling direction, the connection between the main body of the first tab 23 and the main body of the second tab 25, which has been punched out of the contour line between the tab portions, reaches the linear cutting portion 13, and the third punching is performed: The linear cutting portion 13 cuts the connection between the main body of the first tab 23 and the main body of the second tab 25, and the first tab 23 is separated. The front end of the main body of the second tab 25 is located at the frontmost position, and the rear end is connected to the unwound tab. The first contour cutting portion 12 cuts the waste area between the rear end of the second tab 24 and the front end of the third tab 26 and the waste area outside the top end of the second tab 24, and punches the contour line of the front end of the third tab 26 and the entire contour line of the second tab.

[0039] After the base material has advanced by one tab pitch in the pulling direction, the connection between the main body of the first tab 23 and the main body of the second tab 25, which has been punched out of the contour line between the tab portions, reaches the linear cutting portion 13, and the third punching is performed: The linear cutting portion 13 cuts the connection between the main body of the first tab 23 and the main body of the second tab 25, and the first tab 23 is separated. The front end of the main body of the second tab 25 is located at the frontmost position, and the rear end is connected to the unwound tab.

[0040] The first contour cutting portion 12 cuts the waste area between the rear end of the second tab 24 and the front end of the third tab 26 and the waste area outside the top end of the second tab 24, and punches the contour line of the front end of the third tab 26 and the entire contour line of the second tab.

[0041] After the base material has advanced by one tab pitch in the pulling direction, the connection between the main body of the first tab 23 and the main body of the second tab 25, which has been punched out of the contour line between the tab portions, reaches the linear cutting portion 13, and the third punching is performed: The linear cutting portion 13 cuts the connection between the main body of the first tab 23 and the main body of the second tab 25, and the first tab 23 is separated. The front end of the main body of the second tab 25 is located at the frontmost position, and the rear end is connected to the unwound tab.

[0042] The first contour cutting portion 12 cuts the waste area between the rear end of the second tab 24 and the front end of the third tab 26 and the waste area outside the top end of the second tab 24, and punches the contour line of the front end of the third tab 26 and the entire contour line of the second tab.

[0043] Through repeating the above-mentioned cycle of "contour punching -> traction -> straight cutting and next contour punching", combined with the intermittent traction movement of the base material, the continuous slitting production of the pole piece can be realized.

[0044] As can be seen from the above, by applying the knife die structure of the embodiment, the first contour cutting part 12 and the linear cutting part 13 arranged separately on the knife die act on different regions between the adjacent two pole pieces, respectively, and through multiple steps of punching, the slitting of a pole piece is realized in combination with the traction movement of the slitting equipment. Moreover, by adopting the scheme of the embodiment, there is no waste material between the main body parts of the adjacent two pole pieces obtained by slitting, which is beneficial to reduce the waste loss in production and reduce the production cost. More importantly, the cutting path of the linear cutting part 13 must cover the end of the path formed by the last punching of the first contour cutting part 12, so as to cleanly separate the pole pieces and ensure the integrity of the pole piece contour.

[0045] As an illustration of the embodiment, a V-shaped outward protruding blade 15 protruding outward in the direction of the main body part of the pole piece to be slitted is arranged on the cutting edge of the first contour cutting part 12, and the V-shaped outward protruding blade 15 is located in the region where the normal projection of the cutting edge of the linear cutting part 13 on the substrate 11 is located.

[0046] The V-shaped outward protruding blade 15 forms a V-shaped notch concave inward on the outer contour of the main body part of the pole piece when cutting. First, the V-shaped outward protruding blade 15 forms a stress concentration point when punching, so that the punching force required in the cutting process is reduced, which is beneficial to protect the knife die cutting edge and the base material. Secondly, the V-shaped notch provides clear path guidance for the subsequent linear cutting, ensuring that the cutting trajectory of the linear cutting part 13 can accurately connect the cut region. More importantly, the arrangement of the V-shaped outward protruding blade 15 on the cutting edge of the first contour cutting part 12 avoids the material tearing or micro-continuous material phenomenon that is easy to occur at the corner of the right-angle cutting, and ensures the integrity and size consistency of the pole piece contour. In the actual slitting process, the V-shaped outward protruding blade 15 contacts the substrate before the linear cutting part 13 and completes the contour cutting of the outside of the lug, creating favorable cutting conditions for the subsequent linear cutting.

[0047] The detailed pole piece slitting principle is as follows: In the first punching, the first contour cutting part 12 cuts off the waste material of the first length edge of the unwound pole piece, and obtains the contour line of the front end of the first lug part 22 of the first pole piece 23. The V-shaped outward protruding blade 15 on the cutting edge of the first contour cutting part 12 punches a V-shaped notch concave inward in the direction of the main body part at the connection between the main body part and the front end waste of the first pole piece 23.

[0048] After the base material continues to advance along the traction direction by one pole piece spacing, the position where the V-shaped notch has been punched out is just moved to the position below the linear cutting part 13. In the second punching: The linear cutting section 13 cuts precisely along the position of the V-shaped notch formed in the previous step, separating the main body of the first pole piece 23 from the front end waste material; Meanwhile, the first profile cutting section 12 acts on the waste material area between the two pole lug portions of the next set of adjacent first pole piece 23 and second pole piece 25 and the top end of the first pole lug portion 22, cutting the waste material and simultaneously punching a V-shaped notch at the connection between the main body portions of the next set of adjacent first pole piece 23 and second pole piece 25.

[0049] After the substrate continues to advance by one pole piece interval, the area where the V-shaped notch has been punched by the previous cutting is moved precisely below the linear cutting section 13, and when the third cutting is performed: The linear cutting section 13 cuts precisely along the position of the V-shaped notch formed in the previous step, separating the main body of the first pole piece 23 from the front end waste material;

[0050] Meanwhile, the first profile cutting section 12 acts on the waste material area between the two pole lug portions of the next set of adjacent first pole piece 23 and second pole piece 25 and the top end of the first pole lug portion 22, cutting the waste material and simultaneously punching a V-shaped notch at the connection between the main body portions of the next set of adjacent first pole piece 23 and second pole piece 25.

[0051] By repeating the above-mentioned cycle of profile cutting and V-shaped notch pre-cutting between the main body portions of adjacent two pole pieces, pulling, linear cutting, and profile cutting of the end portions of the next set of adjacent two pole pieces and V-shaped notch pre-cutting between the main body portions of adjacent two pole pieces, and combining with the intermittent pulling movement of the substrate, the continuous slitting production of pole pieces can be realized.

[0052] As can be seen from the above, in the first profile cutting section 12 of the present embodiment, the unwound pole piece first passes through the first profile cutting section 12 with a V-shaped convex blade 15, and then passes through the linear cutting section 13. The V-shaped convex blade 15 first punches a V-shaped notch at both ends of the pole piece, releasing part of the stress and defining the corner profile in advance. Then, the linear cutting section cuts at the position of the V-shaped notch, at this time, the cutting is performed on the material that has been partially "isolated" and has less constraint, the cutting force is smaller, the cutting is smoother, and the impact on the tooling and equipment is smaller. It can effectively avoid the generation of burrs at the corner of the pole piece due to material pulling, and the impact on the tooling and equipment is smaller. It can effectively avoid the generation of burrs or micro-continuous material at the corner of the pole piece, significantly improving the cutting quality and yield. And using the V-shaped notch pre-punched by the V-shaped convex blade 15 to position the slitting line between the main body portions of adjacent two pole pieces, the dependence of the system on the pulling precision of the equipment is reduced, the process is robust, and stable production is easy to achieve.

[0053] As a further limitation of the first profile cutout 12 blade structure, the present embodiment provides a specific implementation.

[0054] Embodiment two: knife die suitable for cutting of pole piece.

[0055] Referring to Figures 8 to 12 as shown.

[0056] As an example of the present embodiment, in order to improve the quality of the pole piece, during the coating of the pole piece, a bare area 21 of the current collector, which is not coated with active material, is reserved on the metal foil current collector (such as copper foil, aluminum foil) on both lengthwise side edges, wherein if the lengthwise edge is preset as a tab portion, the width of the bare area 21 of the current collector bare area 21 is slightly greater than the length of the tab portion, so that after cutting along the top end of the tab portion, the outer edge of the wound pole piece is left with a side material allowance; even if only one end of the pole piece is led out as a tab, the metal foil edge on the other side of the wound pole piece without the tab (i.e. the bottom of each pole piece or the side of the tab-free portion) is also reserved with a narrow bare area 21 of the current collector, which is not coated with active material (commonly known as a safety edge or margin).

[0057] The knife die of the present embodiment is provided with opposite first profile cutout 12 and second profile cutout 14, which are respectively located above the bare area 21 of the two lengthwise edges of the unwound pole piece. The profile of the blade of each profile cutout is designed according to the area of the two widthwise end portions of the two pole pieces to be cut off, and the profile can be selected but is not limited to a closed shape, so that the cut-off waste falls automatically without being connected to the edge allowance on the two lengthwise edge sides of the unwound pole piece for stable traction, which is beneficial to maintaining the stability of the traction and avoiding increasing the traction burden. The present embodiment takes the profile of the blade of each profile cutout as a closed surrounding shape as an example, but in practice it can also be set as a non-closed shape, in which case the cut-off waste is connected to the allowance edge of the two lengthwise edges of the unwound pole piece.

[0058] The linear cutting portion 13 on the base plate 11 of the die of the present embodiment extends along the width direction of the unwound pole piece, and is located on one side of the region between the first profile cutting portion 12 and the second profile cutting portion 14. When installed on the slitting device, if the unwound pole piece moves from back to front under the traction, the linear cutting portion 13 is located in the region in front of the first profile cutting portion 12 and the second profile cutting portion 14. The orthographic projection of the two end portions of the blade edge of the linear cutting portion 13 on the base plate 11 falls within the region formed by the extension of the orthographic projection of the blade edge profile of the profile cutting portion on the base plate 11 along the direction in which the linear cutting portion 13 is located. The two end portions of the blade edge of the linear cutting portion 13 are respectively located inside the cutting track formed by the last time stamping of the first profile cutting portion 12 and the second profile cutting portion 14. With this arrangement, the cutting path of the first profile cutting portion 12 and the second profile cutting portion 14 respectively covers the two end portions of the cutting path of the linear cutting portion 13, step stamping is achieved, and continuous material or burrs are avoided.

[0059] Suppose that the current pole piece is a width end portion with a tab, and the die of Embodiment 2 is used for the working principle of pole piece slitting as follows: After the slitting device is started, the unwound pole piece moves along the traction direction, the first profile cutting portion 12 and the second profile cutting portion 14 on the die are respectively located above the current collector bare area 21 on both length edge sides of the unwound pole piece, the orthographic projection region of the blade edge profile of the profile cutting portion on the pole piece is located within the current collector bare area 21 on both length edge sides of the unwound pole piece, and does not exceed the two length edges. The linear cutting portion 13 on the die extends along the width direction of the unwound pole piece, the length of the blade edge of the linear cutting portion 13 is less than the width of the unwound pole piece, and the orthographic projection of the blade edge of the linear cutting portion 13 on the pole piece exceeds the coating width of the polar active material layer 29 of the pole piece and is located within the blanking area on both length edge sides of the pole piece, and does not exceed the two length edges of the pole piece. In this way, stamping is performed using the die of the present embodiment, the first profile cutting portion 12, the second profile cutting portion 14, and the linear cutting portion 13 all act on the two length edges of the unwound pole piece, and after each stamping, a predetermined length edge allowance is left on both length edges of the unwound pole piece to ensure the stability of the unwound traction.

[0060] At the stamping station, when stamping for the first time: The first profile cutting portion 12 cuts off the waste material of the end portion of the first pole piece 23 on the first length edge of the unwound pole piece, and forms the profile line of the front end of the first tab 22 of the first pole piece 23; the second profile cutting portion 14 cuts off the waste material of the bottom of the front half of the main body portion of the first pole piece 23 on the second length edge side; at this time, the blade edge of the linear cutting portion 13 in front is below the stamping object, and the main body portion of the first pole piece 23 is connected to the unwound pole piece.

[0061] After the substrate continues to advance by one tab pitch in the pulling direction, the connection position between the main body of the first tab 23 and the main body of the second tab 25, which have been punched out of the contour lines of the front end of the second tab 24 and the rear end of the first tab 22, reaches below the linear cutting portion 13, and a third punching is performed: The linear cutting portion 13 cuts the connection between the front end edge of the main body of the first tab 23 and the front end waste, and punches one edge of the main body of the first tab 23, and the rear end of the first tab 23 is still connected to the unwound tab; The first contour cutting portion 12 cuts the waste area between the rear end of the first tab 22 and the front end of the second tab 24, and cuts the waste area outside the top end of the first tab 22, and punches the contour line of the front end of the second tab 24 and punches the entire contour line of the first tab 22; The second contour cutting portion 14 cuts the waste area outside the remaining rear half of the bottom of the main body of the first tab 23 and the front half of the bottom of the main body of the second tab 25, After the substrate continues to advance by one tab pitch in the pulling direction, the connection position between the main body of the first tab 23 and the main body of the second tab 25, which have been punched out of the contour lines of the front end of the second tab 24 and the rear end of the first tab 22, reaches below the linear cutting portion 13, and a third punching is performed: The linear cutting portion 13 cuts the connection between the front end edge of the main body of the first tab 23 and the front end waste, and punches one edge of the main body of the first tab 23, and the rear end of the first tab 23 is still connected to the unwound tab;

[0062] The first contour cutting portion 12 cuts the waste area between the rear end of the first tab 22 and the front end of the second tab 24, and cuts the waste area outside the top end of the first tab 22, and punches the contour line of the front end of the second tab 24 and punches the entire contour line of the first tab 22; The second contour cutting portion 14 cuts the waste area outside the remaining rear half of the bottom of the main body of the first tab 23 and the front half of the bottom of the main body of the second tab 25,

[0063] By repeating the above punching process, combined with the intermittent pulling movement of the substrate, the continuous slitting production of the tab can be realized.

[0064] In addition to the application benefits of the die of the first embodiment, the die of the present embodiment can also cut off the waste material at the bottom end of the adjacent two pole pieces, the first profile cutting portion 12 and the second profile cutting portion 14 respectively perform secondary punching on the profile position of the linear cutting portion 13 at the top end and the bottom end of the pole piece in the last punching, ensuring that the waste material outside the profile of the separated pole piece is cut off completely, and improving the cutting effect of the pole piece. On the other hand, the die of the second embodiment leaves a predetermined length edge allowance on both length edge sides of the unwound pole piece after punching to ensure the traction stability of the unwound pole piece, thereby further ensuring the cutting effect.

[0065] As an illustration of the present embodiment, the opposite blade edges of the first profile cutting portion 12 and the second profile cutting portion 14 are respectively provided with outwardly protruding V-shaped protruding blades 15, the two V-shaped protruding blades 15 are opposite to each other, which can be but not limited to mirror symmetry, and both of the V-shaped protruding blades 15 are located in the area where the normal projection of the blade edge of the linear cutting portion 13 on the substrate 11 is located. The two V-shaped protruding blades 15 form two opposite V-shaped cutouts at the top and bottom of the outer profile of the main body of the pole piece when cutting. The working principle and benefits thereof are described in detail in the corresponding description of the first embodiment.

[0066] The detailed pole piece cutting principle is as follows: In the first punching, the first profile cutting portion 12 and the second profile cutting portion 14 cut off the waste material of the first length edge of the unwound pole piece, obtaining the profile line of the front end of the first pole lug 22 of the first pole piece 23 and the bottom end profile line of the first pole piece 23. The V-shaped protruding blades 15 on the blade edge profile of the first profile cutting portion 12 and the second profile cutting portion 14 respectively punch to form two V-shaped cutouts respectively located at the top and bottom of the main body of the pole piece at the connection between the main body of the first pole piece 23 and the front end waste material, and the two V-shaped cutouts are opposite to each other.

[0067] After the substrate continues to move forward by one pole piece pitch in the traction direction, the positions where the two opposite V-shaped cutouts have been punched out are just moved to the position below the linear cutting portion 13. In the second punching: The linear cutting portion 13 accurately cuts along the connecting line between the two opposite V-shaped cutouts formed in the last step to separate the main body of the first pole piece 23 from the front end waste material; At the same time, the first profile cutting portion 12 acts on the waste material area between the two pole lug portions of the adjacent first pole piece 23 and second pole piece 25 and the waste material area outside the top end of the first pole lug 22 to cut off the waste material, and punches out a V-shaped cutout at the connection between the top ends of the main bodies of the adjacent first pole piece 23 and second pole piece 25; The second profile cutting section 14 acts on the waste area outside the rear half of the main body of the adjacent first pole piece 23 and the front half of the main body of the second pole piece 25, cutting the waste material while punching a V-shaped cut opposite to the V-shaped cut at the top end between the connecting part of the main body of the adjacent first pole piece 23 and the second pole piece 25.

[0068] After the substrate continues to advance in the pulling direction by one pole piece interval, the area where two opposite V-shaped cuts have been punched by the previous punching is just moved to below the linear cutting section 13, and when the third punching is performed: The linear cutting section 13 accurately cuts along the connecting line between the two V-shaped cuts formed in the previous step, cutting the connecting part between the main bodies of the first pole piece 23 and the second pole piece 25, and the first pole piece 23 is separated.

[0069] At the same time, the first profile cutting section 12 acts on the waste area between the two pole lug parts of the adjacent second pole piece 25 and third pole piece 27 and the waste area outside the top end of the second pole lug part 24, cutting the waste material while punching a V-shaped cut between the top ends of the main bodies of the adjacent second pole piece 25 and third pole piece 27; The second profile cutting section 14 acts on the waste area outside the rear half of the main body of the adjacent second pole piece 25 and the front half of the main body of the third pole piece 27, cutting the waste material while punching a V-shaped cut opposite to the V-shaped cut at the top end between the bottom ends of the main bodies of the adjacent second pole piece 25 and third pole piece 27.

[0070] By repeating the above-mentioned "profile punching and pre-cutting of two opposite V-shaped cuts between the main bodies of the adjacent two pole pieces, pulling, linear cutting, and profile punching of the end parts of the next adjacent two pole pieces and pre-cutting of two opposite V-shaped cuts between the main bodies of the adjacent two pole pieces" cycle, combined with the intermittent pulling movement of the substrate, the continuous slitting production of the pole pieces can be realized.

[0071] As can be seen from the above, due to the V-shaped convex edges 15 arranged on the cutting edges of the first profile cutting part 12 and the second profile cutting part 14, the unwound pole piece first passes through the profile cutting part with the V-shaped convex edges 15, and then passes through the linear cutting part 13. The V-shaped convex edges 15 first punch out V-shaped notches at both ends of the pole piece, release part of the stress, and define the corner profile in advance. Then, the linear cutting part punches at the position of the connecting line between the two V-shaped notches, at this time, the cutting is performed on the material which has been partially "isolated" and has less constraint, the cutting force is smaller, the cutting is smoother, the burr caused by material pulling at the corner can be effectively avoided, the impact on the tooling and equipment is also smaller. The burr or micro-continuous material at the corner of the pole piece is effectively avoided, and the cutting quality and yield are significantly improved. Moreover, the two opposite V-shaped notches pre-punched by the two opposite V-shaped convex edges 15 can be used to position the split line between the main bodies of the two adjacent pole pieces, the dependence of the system on the traction accuracy of the equipment is further reduced, and the process robustness is stronger, and stable production is easier to achieve.

[0072] The V-shaped convex edges 15 on the cutting edges of each profile cutting part in the first embodiment and the second embodiment can be formed by bending a knife in actual production, and the included angle of the V-shaped convex edges 15 is controlled to be between 30° and 150°.

[0073] The inventor found during the research of the present application that when the included angle is less than 30°, the V-shaped convex edges 15 of the cutting edge are too sharp, although the cutting resistance is small, the wear resistance and strength of the sharp corner part of the cutting edge will decrease in continuous punching, which affects the service life of the tooling; when the included angle is greater than 150°, the V-shaped feature of the cutting edge tends to be flat, the effect of guiding the cutting path and stress concentration will be weakened, which is closer to linear cutting, and is not conducive to avoiding corner burrs. Therefore, by limiting the included angle to be between 30° and 150°, a balance between the cutting quality and the service life of the tooling can be achieved.

[0074] As an equivalent alternative, each V-shaped convex edge 15 can also be implemented as a circular arc convex edge. The circular arc convex edge is formed by a corresponding grinding process, and the radius of the circular arc can be adjusted according to the thickness and characteristics of the pole piece material.

[0075] ​As can be seen from the above, whether it is a V-shaped angle within a specific angle range or a circular arc structure, the convex geometry can concentrate stress on the blade tip during punching. This effectively reduces the total pressure required during the punching process, making the punching action more labor-saving and smooth. Moreover, the V-shaped or circular arc convex blade cuts before the linear cutting portion 13, forming a regular guide cut at the corner of the profile between the two adjacent pole pieces. This allows the straight blade of the subsequent linear cutting portion 13 to accurately "blend" into the pre-cut path, thereby ensuring smooth transition of the two cutting actions in mechanical structure, and fundamentally avoiding burrs or incomplete cutting of the connecting material at the key corner position. Moreover, the 30° to 150° included angle range and the circular arc alternative provided by the embodiment of the application provide flexibility for the design of the die to adapt to different pole piece materials (such as graphite, silicon-carbon negative electrode, etc. corresponding foil) and thickness requirements. For harder or thicker materials, a design with a slightly larger angle or a slightly larger circular arc radius can be selected to balance the cutting effect and blade strength.

[0076] As an example of the present embodiment, each profile cutting portion and / or linear cutting portion 13 in embodiments one and two is implemented by a white steel blade nested on the base plate 11.

[0077] As an example of the present embodiment, the base plate 11 on the die can be but is not limited to a PVC plate.

[0078] Embodiment three: a pole piece slitting device.

[0079] The present embodiment provides a pole piece slitting device for implementing the pole piece slitting process described in embodiment one or embodiment two.

[0080] The slitting device comprises: A rack: as the support body of the device.

[0081] A unwinding device: arranged at one end of the rack, for carrying and unwinding the continuous pole piece substrate in a roll.

[0082] A traction device: arranged downstream of the unwinding device, for guiding and accurately controlling the intermittent movement of the substrate along the predetermined slitting path. The traction device can use high-precision clamping traction rollers or synchronous belt traction mechanisms to ensure the accuracy of the pole piece step distance.

[0083] A die assembly: the core working component. It comprises: A die holder: fixedly installed on the rack.

[0084] A die as described in any one of embodiments one and two: arranged above the slitting path by the die holder, with the blade of the die facing the substrate.

[0085] Driving device: connected with the die, used to drive the die to perform the punching motion perpendicular to the base material direction. The driving device can be preferably a servo motor driven press or a pneumatic cylinder to ensure the stability and controllability of the punching force.

[0086] Control unit: electrically connected with the unwinding device, the traction device and the die driving device, used to control the action sequence and timing of each execution component to ensure the accurate performance of the slitting process cycle.

[0087] The working process of the equipment is programmed and controlled by the control unit, and the specific process is as follows: Loading and initialization: install the roll-shaped base material on the unwinding device, and pull it through the traction device to lay it on the slitting path below the die.

[0088] Start the cycle: the control unit issues instructions, and the equipment starts to run automatically.

[0089] First traction: the traction device acts to drive the base material to advance accurately by a preset tab pitch.

[0090] First cutting: the driving device of the die starts to push the die down to cut. In this process: The profile cutting part cuts out the profile of the current tab end (tab ear area or safety edge) on the base material.

[0091] Due to the setting of the traction step, the linear cutting part 13 may not participate in effective cutting or perform preliminary cutting this time.

[0092] Second traction: after the first cutting is completed, the die retreats, and the traction device acts again to advance the base material by a tab pitch.

[0093] Second cutting: the die is pressed down again to perform cutting. This time: The profile cutting part cuts the end profile of the next group of tabs.

[0094] At the same time, the linear cutting part 13 accurately cuts along the path end (or V-shaped guide cut) formed by the previous profile cutting part to separate a complete tab.

[0095] Cycle and material collection: repeat the traction-cutting cycle steps. The qualified tabs completely separated are collected by the downstream collection device (such as a belt conveying line or a material box). The waste generated by the cutting is removed by a special waste collection system (such as a negative pressure adsorption device).

[0096] The slitting equipment provided in the embodiment has the following significant advantages by integrating the innovative die: Thanks to the waste-free slitting design of the die, the equipment can greatly reduce the waste of raw materials in the tab production process and significantly reduce the production cost.

[0097] The precise traction control of the device is combined with the step-by-step cutting structure of the die, which fundamentally avoids the corner burr and micro-continuous material problems of the pole piece, and ensures the consistency of the size and contour of the pole piece in batch production.

[0098] The device decomposes the complex cutting process into simple repeated steps, reduces the extreme requirement for the precision of a single punching action, makes the whole system run more stably, has a lower failure rate, and is easy to realize long-time continuous automatic production.

[0099] By replacing different dies, the device can quickly adapt to the production needs of pole pieces of different specifications and different tab designs, and the type replacement is convenient, which is very suitable for small-batch, multi-variety battery research and manufacturing scenarios.

[0100] In summary, the device embodiment provides an advanced solution for the high-quality, low-cost and flexible production of lithium battery pole pieces.

[0101] The above-described embodiments do not constitute a limitation on the protection scope of the technical solutions. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the above-described embodiments shall be included in the protection scope of the technical solutions.

Claims

1. A knife die suitable for slitting of electrode segments, comprising a base plate, characterized in that, The substrate is provided with: at least one profiled cutting portion, the profile of the cutting edge of which matches the region of the waste material to be cut between the two adjacent pole pieces; a linear cutting portion, the cutting edge of which is linear and extends along the width direction of the substrate, wherein the linear cutting portion is provided separately from each profiled cutting portion, and the end of the cutting edge of the linear cutting portion, which is proximal to each profiled cutting portion, is projected onto the substrate, and the projection falls within the region formed by the projection of the profile of the cutting edge of the profiled cutting portion onto the substrate along the direction in which the linear cutting portion is located.

2. The cutting die suitable for cutting pole pieces according to claim 1, wherein: a V-shaped or circular-arc-shaped protruding blade is provided on the cutting edge of each profiled cutting portion, the blade protruding outward from the profile of the cutting edge, the V-shaped or circular-arc-shaped protruding blade is located in the region in which the projection of the cutting edge of the linear cutting portion onto the substrate is located.

3. The cutting die suitable for cutting pole pieces according to claim 2, wherein: the included angle of the V-shaped protruding blade ranges from 30° to 150°.

4. The cutting die suitable for cutting pole pieces according to claim 2 or 3, wherein: two opposite profiled cutting portions are included, the linear cutting portion is located on the same side of the two profiled cutting portions.

5. The cutting die suitable for cutting pole pieces according to claim 4, wherein: the two ends of the projection of the cutting edge of the linear cutting portion onto the substrate fall within the regions formed by the projections of the profiles of the cutting edges of the two profiled cutting portions onto the substrate along the direction in which the linear cutting portion is located.

6. The cutting die suitable for cutting pole pieces according to claim 1 or 2 or 3, wherein: the profiled cutting portion and / or the linear cutting portion is a white steel blade.

7. The cutting die suitable for cutting pole pieces according to claim 1 or 2 or 3, wherein: the substrate is a PVC plate.

8. An apparatus for slitting electrode sheets, used to slit a continuous sheet-like substrate into a plurality of independent electrode sheets, characterized in that, The device comprises: an unwinding device for unwinding the continuous sheet-shaped substrate; a traction device for guiding the movement of the substrate along a cutting path; the cutting die according to any one of claims 1 to 7, which is arranged above the cutting path and has the cutting edges of the profiled cutting portions and the linear cutting portion facing the substrate; and a driving device for driving the cutting die to perform a punching movement towards the substrate.

9. The device for cutting pole pieces according to claim 8, wherein: each profiled cutting portion is located in front of the linear cutting portion along the traction direction of the substrate.

10. A method for cutting pole pieces using the cutting die suitable for cutting pole pieces according to claims 1 to 7.

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