Lithium battery winding pole piece cutting method

Abstract

The invention discloses a lithium battery winding pole piece cutting method which comprises the steps that a winding machine is used for winding a winding pole piece in the winding direction, the winding pole piece is provided with at least one first blank area and at least one second blank area in the winding direction, the first blank area is used for arranging a pole lug, and the second blank area is the cutting position of the winding pole piece; a second blank area, closest to the winding machine, of the winding pole piece is cut in the winding direction, the winding pole piece is cut into a front pole piece and a rear pole piece, and the front pole piece is connected with the winding machine; separating the front pole piece from the rear pole piece by a first distance; sticking an adhesive tape at the first interval to connect the front pole piece and the rear pole piece, wherein the adhesive tape has certain transparency; after the winding machine finishes winding the front pole piece, finding out a first distance by utilizing a transparency detection device; and cutting off the adhesive tape in the first interval. The position of the first interval can be accurately recognized, the foil area can be prevented from being cut when the adhesive tape is cut off, and the reject ratio of products is reduced.

Description

Technical Field

[0001] This application relates to the field of lithium batteries, and particularly to a method for cutting a wound pole piece of a lithium battery. Background Art

[0002] In the existing method, when winding the wound pole piece of a lithium-ion battery, the distance from the fixed length of the tab to the cutting position is obtained, and the cutting is made to the middle position of the adhesive tape according to this distance. However, in the actual operation process, the foil areas for welding the tabs and cutting the adhesive tape are not the same. Affected by the error of the running length of the wound pole piece, the skew of the tabs, etc., it is easy to cut into the foil area, and then burrs, metal particles, etc. will be generated in the foil area. Currently, there is a lack of an effective method for identifying the cutting method. After these defective products flow into the subsequent processes, it will cause safety risks such as poor voltage drop of the final battery product, overheating and explosion, micro-short circuit, self-discharge, and failure of the entire PACK battery pack. Summary of the Invention

[0003] The purpose of this application is to provide a method for cutting a wound pole piece of a lithium battery, which is not easy to cut into the foil area and can reduce the defective rate of the product.

[0004] To achieve the above purpose, this application provides a method for cutting a wound pole piece of a lithium battery, including: Using a winding machine to wind the wound pole piece along the winding direction. The wound pole piece is provided with at least one first blank area and at least one second blank area along the winding direction. The first blank area is used to set the tab, and the second blank area is the cutting position of the wound pole piece; Cutting the second blank area closest to the winding machine along the winding direction of the wound pole piece. The wound pole piece is cut into a front pole piece and a rear pole piece, and the front pole piece is connected to the winding machine; Separating the front pole piece and the rear pole piece by a first distance; Sticking a tape at the first distance to connect the front pole piece and the rear pole piece. The tape has a certain transparency; After the winding machine finishes winding the front pole piece, using a transparency detection device to find the first distance; Cutting off the tape within the first distance.

[0005] Compared with the prior art, in the present application, the wound pole piece is cut into a front pole piece and a rear pole piece in the second blank area, the front pole piece and the rear pole piece are separated by a first distance, a tape is attached at the first distance to connect the front pole piece and the rear pole piece. After the winding machine finishes winding the front pole piece, the transparency detection device is used to find the first distance, and the tape is cut within the first distance. Since the wound pole piece is not transparent while the tape has a certain transparency, the transparency detection device can accurately distinguish between the two, so as to accurately identify the location of the first distance, and avoid cutting the foil area when cutting the tape, reducing the defect rate of the product.

[0006] Optionally, when attaching the tape at the first distance, the winding of the winding machine is paused; After attaching the tape at the first distance, the winding machine is used to continue winding the front pole piece.

[0007] Optionally, separating the front pole piece and the rear pole piece by the first distance includes: Pressing the front pole piece and moving the front pole piece along the winding direction; And / or, Pressing the rear pole piece and moving the rear pole piece in a direction opposite to the winding direction.

[0008] Optionally, the width of the first distance along the winding direction is 4 - 5 mm.

[0009] Optionally, the transparency detection device is used to detect the positions of both edges of the first distance along the winding direction; According to the positions of both edges of the first distance along the winding direction, the middle position of the first distance along the winding direction is determined, and the tape is cut perpendicular to the winding direction at the middle position.

[0010] Optionally, the transparency detection device is an opposed fiber optic, the opposed fiber optic includes a transmitting end and a receiving end, and the wound pole piece is arranged on the optical path between the transmitting end and the receiving end.

[0011] Optionally, the optical path of the transmitting end and the receiving end is perpendicular to the plane where the wound pole piece is located. Description of the Drawings Figure 1 It is a schematic diagram of the wound pole piece involved in the present application.

[0012] Figure 2 It is a schematic diagram of the cut wound pole piece involved in the present application.

[0013] Figure 3 It is a schematic diagram of the prior art using the tab to secondarily cut the wound pole piece.

[0014] Figure 4 It is a schematic diagram of the ear being deflected when the prior art uses secondary cutting to wind the pole piece with the tab.

[0015] Figure 5 It is a flowchart of the method for cutting the wound pole piece of the lithium battery according to the embodiment of the present application.

[0016] Figure 6 It is a schematic diagram of secondary cutting and winding the pole piece according to the embodiment of the present application. Detailed implementation mode

[0017] To describe in detail the technical content, structural features, achieved purposes and effects of the present application, the following will be described in detail in conjunction with the implementation modes and with reference to the accompanying drawings.

[0018] Please refer to Figure 1 , at least one first blank area 11 and at least one second blank area 12 are arranged on the wound pole piece 1 along the winding direction F1. The first blank area 11 is used to arrange the tab 2, and the second blank area 12 is the cutting position of the wound pole piece 1. Among them, between two adjacent second blank areas 12 and between the second blank area 12 near the end of the core pole piece 1 and the end of the wound pole piece 1, one or more first blank areas 11 can be arranged, which can be adjusted according to actual situations and are not specifically limited.

[0019] Please refer to Figures 1 to 4 , in a method for cutting a wound pole piece of a lithium battery in the prior art, the wound pole piece 1 is first cut into a front pole piece 13 and a rear pole piece 14 in the second blank area 12, and then the front pole piece 13 and the rear pole piece 14 are pulled apart by a first distance J1 in the winding direction F1, and a layer of tape 3 is pasted at the first distance J1 to connect the front pole piece 13 and the rear pole piece 14; the distance D1 between the tab 2 arranged on the first blank area 11 and the tape 3 arranged on the second blank area 12 is determined, and the midpoint position of the first distance J1 along the winding direction F1 is obtained through the distance D1, and the tape 3 is cut at the midpoint position (that is, along the winding direction F1, the tape is cut at a distance of D1 from the tab 2). Because the tab 2 is prone to deflection when welded to the first blank area 11, the distance measurement is inaccurate, and the distance from the tab 2 to the cutting position is much larger than the width of the first distance J1 along the winding direction F1, and the related measurement errors are easily ignored. This solution is likely to cut into the foil area of the front pole piece 13 and / or the rear pole piece 14, resulting in burrs, metal particles, etc. on the front pole piece 13 and / or the rear pole piece 14, affecting the normal operation of the subsequent processes.

[0020] In this regard, please refer to Figure 1 , Figure 2 , Figure 5 and Figure 6 , the present application discloses a method for cutting a wound pole piece of a lithium battery, including: S1. Use a winding machine (not shown in the figure) to wind the wound pole piece 1 along the winding direction F1.

[0021] S2. Cut the second blank area 12 of the wound pole piece 1 that is closest to the winding machine along the winding direction F1. The wound pole piece 1 is cut into a front pole piece 13 and a rear pole piece 14, and the front pole piece 13 is connected to the winding machine.

[0022] S3. Separate the front pole piece 13 and the rear pole piece 14 by a first distance J1.

[0023] In some embodiments, step S3 includes: pressing the front pole piece 13 and moving the front pole piece 13 along the winding direction F1, and / or pressing the rear pole piece 14 and moving the rear pole piece 14 in the direction opposite to the winding direction F1.

[0024] Specifically, tools such as a pressure roller can be used to press the front pole piece 13 and / or the rear pole piece 14. This is a well-known technical means for those skilled in the art and will not be elaborated here.

[0025] Please refer to Figure 6 , in some embodiments, the width D2 of the first distance J1 along the winding direction F1 is 4 - 5 mm. Ensure that when the tape 3 is attached, the tape 3 can connect the front pole piece 13 and the rear pole piece 14, and the second blank area 12 at the first distance J1 will not be cut when the tape 3 is cut later.

[0026] S4. Attach the tape 3 at the first distance J1 to connect the front pole piece 13 and the rear pole piece 14. The tape 3 has a certain transparency.

[0027] In some embodiments, when attaching the tape 3 at the first distance J1, the winding of the winding machine is paused; after attaching the tape 3 at the first distance J1, the winding machine is used to continue winding the front pole piece 13, ensuring that when the tape 3 is attached, the tape 3 can be accurately attached to the first distance J1 and connect the front pole piece 13 and the rear pole piece 14, guaranteeing the normal operation of subsequent operations.

[0028] S5. After the winding machine finishes winding the front pole piece 13, use the transparency detection device 4 to find the first distance J1.

[0029] Please refer to Figure 6, in some embodiments, the transparency detection device 4 is an opposed fiber optic, and the opposed fiber optic includes a transmitting end 41 and a receiving end 42. The receiving end 42 determines the photosensitive value according to the intensity of the laser emitted from the transmitting end 41. The greater the intensity of the received laser, the higher the photosensitive value. Therefore, when an object blocks the laser emitted by the transmitting end 41, whether the part blocking the laser is fully transparent, semi-transparent or opaque can be known through the photosensitive value of the opposed fiber optic. The wound pole piece 1 is arranged on the optical path G1 between the transmitting end 41 and the receiving end 42 of the transparency detection device 4. That is to say, the light emitted by the transmitting end 41 will shine on the wound pole piece 1. When the corresponding position of the wound pole piece 1 is transmissive, at least part of the light will be received by the receiving end 42. When the corresponding position of the wound pole piece 1 is non-transmissive, the receiving end 42 cannot receive the light from the transmitting end 41. When the first spacing J1 after the tape 3 is pasted passes through the optical path G1 of the opposed fiber optic, the photosensitive value of the opposed fiber optic is relatively high (for example, the photosensitive value is 4095, of course, depending on the transparency of the specific tape 3). When the front pole piece 13 and the rear pole piece 14 pass through the optical path G1 of the opposed fiber optic, since the front pole piece 13 and the rear pole piece 14 are basically non-transmissive, the light emitted from the transmitting end 41 will be blocked by the front pole piece 13 and the rear pole piece 14. At this time, the photosensitive value of the opposed fiber optic is relatively low (for example, the photosensitive value is 0).

[0030] It can be understood that the transparency detection device 4 can move relative to the wound pole piece 1 to perform detection at different positions in the winding direction F1.

[0031] Optionally, the optical path G1 between the transmitting end 41 and the receiving end 42 is perpendicular to the plane where the wound pole piece 1 (the unwound planar part) is located.

[0032] S6, cut the tape 3 within the first spacing J1.

[0033] Please refer to Figure 6 , specifically, use the transparency detection device 4 to detect the positions of both edges of the first spacing J1 along the winding direction F1; determine the middle position Z1 of the first spacing J1 along the winding direction F1 according to the positions of both edges of the first spacing J1 along the winding direction F1, and cut the tape 3 perpendicular to the winding direction F1 at the middle position Z1.

[0034] Since there is a difference in transparency between the tape 3 and the front pole piece 13 and the rear pole piece 14, the transparency detection device 4 can detect the position and length D2 of the first spacing J1, and then the middle position Z1 of the first spacing J1 can be obtained and the tape 3 can be cut at the middle position Z1, which can prevent the wound pole piece 1 from being slightly deflected and cutting into the second blank area 12 when the winding machine winds the wound pole piece 1.

[0035] When the transparency detection device 4 is the above-mentioned opposed fiber optic, the calculation effect of the length D2 of the first spacing J1 is more accurate.

[0036] Compared with the prior art, in the present application, the wound pole piece 1 is cut into a front pole piece 13 and a rear pole piece 14 in the second blank area 12, and the front pole piece 13 and the rear pole piece 14 are separated by a first distance J1. A tape 3 is attached at the first distance J1 to connect the front pole piece 13 and the rear pole piece 14. After the winding machine finishes winding the front pole piece 13, the transparency detection device 4 is used to find the first distance J1, and the tape 3 is cut within the first distance J1. Since the wound pole piece 1 does not have transparency while the tape 3 has a certain transparency, the transparency detection device 4 can accurately distinguish the two, so as to accurately identify the location of the first distance J1, and avoid cutting the foil area when cutting the tape 3, reducing the defective rate of the product. At the same time, in the present application, the part of the wound pole piece 1 that directly contacts the separator after cutting can be the tape instead of the second blank area 12 or the coating dressing area, completely eliminating the risk of piercing and short circuit caused by the direct contact of the coating dressing area or the second blank area 12 with the separator.

[0037] The above-disclosed are only the preferred embodiments of the present application, and of course cannot be used to limit the scope of rights of the present application. Therefore, equivalent changes made according to the scope of the patent of the present application still fall within the scope covered by the present application.

Claims

1. A method for cutting a lithium battery wound pole piece, characterized in that, Including: Using a winding machine to wind the wound pole piece along the winding direction. The wound pole piece is provided with at least one first blank area and at least one second blank area along the winding direction. The first blank area is used to set the tab, and the second blank area is the cutting place of the wound pole piece. Cutting the second blank area closest to the winding machine along the winding direction of the wound pole piece. The wound pole piece is cut into a front pole piece and a rear pole piece, and the front pole piece is connected to the winding machine. Separating the front pole piece and the rear pole piece by a first distance. Sticking a tape at the first distance to connect the front pole piece and the rear pole piece. The tape has a certain transparency. After the winding machine finishes winding the front pole piece, using a transparency detection device to find the first distance. Cutting off the tape within the first distance.

2. The lithium battery winding pole piece cutting method according to claim 1, characterized in that When sticking the tape at the first distance, pausing the winding of the winding machine. After sticking the tape at the first distance, using the winding machine to continue winding the front pole piece.

3. The method for cutting a wound pole piece of a lithium battery according to claim 2, wherein The separating the front pole piece and the rear pole piece by the first distance includes: Pressing the front pole piece and moving the front pole piece along the winding direction. And / or Pressing the rear pole piece and moving the rear pole piece in a direction opposite to the winding direction.

4. The method for cutting a wound pole piece of a lithium battery according to claim 1, wherein, Including: The width of the first distance along the winding direction is 4 - 5 mm.

5. The method for cutting a lithium battery wound pole piece according to claim 1, wherein, Using the transparency detection device to detect the positions of both edges of the first distance along the winding direction. Determining the middle position of the first distance along the winding direction according to the positions of both edges of the first distance along the winding direction, and cutting off the tape perpendicular to the winding direction at the middle position.

6. The method for cutting a wound pole piece of a lithium battery according to claim 1 or 5, wherein The transparency detection device is an opposed fiber optic. The opposed fiber optic includes a transmitting end and a receiving end, and the wound pole piece is arranged on the optical path between the transmitting end and the receiving end.

7. The method for cutting a wound pole piece of a lithium battery according to claim 6, wherein The optical path of the transmitting end and the receiving end is perpendicular to the plane where the wound pole piece is located.

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