A battery core winding method

Abstract

A battery cell winding method comprises the following steps: a single-pole sheet unwinding mechanism and a composite-pole sheet unwinding mechanism output a single-pole sheet and a composite-pole sheet, respectively; the single-pole sheet and the composite-pole sheet are intermittently composited at an intermittent composite mechanism to form an integral composite sheet; the single-pole sheet and the integral composite sheet are towed by first and second material belt traction mechanisms, respectively; the composite process of the intermittent composite mechanism includes a composite time period and a non-compounding time period; during the composite time period, the traction speed of the first material belt traction mechanism is the same as the traction speed of the second material belt traction mechanism, and the intermittent composite mechanism composites the composite-pole sheet and the single-pole sheet together; during the non-compounding time period, the traction speed of the first material belt traction mechanism is greater than the traction speed of the second material belt traction mechanism, and the intermittent composite mechanism does not composite the single-pole sheet and the composite-pole sheet; the integral composite sheet is wound at a winding mechanism to form a battery cell. The present invention can flexibly adjust the compensation value of the inner and outer layer electrode sheet lengths, improve the battery cell winding quality, and has a wide compatibility range.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium batteries, and in particular relates to a battery cell winding method for winding composite pole pieces and conventional pole pieces. Background Art

[0002] Lithium battery cells are primarily manufactured using two processes: winding and lamination. The winding process involves winding the electrode sheets and separators using a winder to create a battery cell. Compared to lamination, the winding process is more efficient and therefore more widely used. Traditionally, the positive and negative electrode sheets and two separators are unwound separately, then wound on a winding needle to form a battery cell. This process, due to the large number of strips, struggles with winding accuracy and efficiency. To address these challenges, a new approach has emerged, combining the separator and the negative electrode sheet to form a negative electrode sheet. This composite electrode sheet features a separator-electrode-separator structure. After the separator and negative electrode sheet are thermally laminated, the composite electrode sheet and the positive electrode sheet are then wound on a winding needle to form a battery cell. Because the separator and negative electrode sheet are pre-laminated, only the composite electrode sheet and positive electrode sheet need to be wound on the winding needle to form the battery cell. This reduces the number of strips and improves winding accuracy and efficiency. However, when winding composite pole pieces and single pole pieces, there is a problem of wrinkling due to the length difference between the inner and outer layers, which affects the winding quality. Chinese invention patent application No. 2023114421908 discloses a battery cell winding method that can achieve compensation for the length difference of the pole pieces through special winding. However, the pole piece length compensation value of this method is inconvenient to adjust, and the battery compatibility range is limited. Moreover, with the improvement of battery cell energy density, silicon-based negative pole pieces with high energy density are gradually being promoted. Since silicon-based negative pole pieces have a higher expansion rate, there are also higher requirements for controlling the length of positive and negative pole pieces inside lithium batteries. Summary of the Invention

[0003] The object of the present invention is to provide a battery cell winding method for winding composite pole pieces and conventional pole pieces, which is convenient for adjusting the compensation length of inner and outer pole pieces and improving the winding accuracy.

[0004] In order to achieve the above objectives, the present invention adopts the following technical solutions:

[0005] A battery cell winding method uses a battery cell winding device to wind a composite electrode sheet and a single electrode sheet into a battery cell. The battery cell winding device includes a single electrode sheet unwinding mechanism, a composite electrode sheet unwinding mechanism, a first material strip pulling mechanism, a second material strip pulling mechanism, an intermittent compounding mechanism, and a winding mechanism.

[0006] The battery core winding method comprises the following steps:

[0007] The single pole piece unwinding mechanism outputs the single pole piece, and the composite pole piece unwinding mechanism outputs the composite pole piece;

[0008] The single-pole sheet and the composite electrode sheet are intermittently composited at the intermittent composite mechanism to obtain an integral composite sheet; the single-pole sheet is pulled by the first material belt traction mechanism, and the integral composite sheet is pulled by the second material belt traction mechanism; the process of the intermittent composite mechanism composites the single-pole sheet and the composite electrode sheet, including a composite time period and a non-composite time period. During the composite time period, the traction speed of the first material belt traction mechanism is the same as the traction speed of the second material belt traction mechanism, and the intermittent composite mechanism composites the composite electrode sheet and the single-pole sheet together. During the non-composite time period, the traction speed of the first material belt traction mechanism is greater than the traction speed of the second material belt traction mechanism, and the intermittent composite mechanism does not composite the single-pole sheet and the composite electrode sheet.

[0009] The integral composite sheet is wound at the winding mechanism to form a battery core.

[0010] Furthermore, the composite electrode sheet includes a negative electrode sheet and a diaphragm composited on both sides of the negative electrode sheet, and the single electrode sheet is a positive electrode sheet; or, the composite electrode sheet includes a positive electrode sheet and a diaphragm composited on both sides of the positive electrode sheet, and the single electrode sheet is a negative electrode sheet.

[0011] Furthermore, in the non-composite time period, the traction speed difference is adjusted according to the required length compensation value, and the traction speed difference=the traction speed of the first material belt traction mechanism-the traction speed of the second material belt traction mechanism.

[0012] Furthermore, the length compensation value=traction speed difference×the duration of the non-compound time period.

[0013] Furthermore, the first material strip traction mechanism is located downstream of the single-pole sheet unwinding mechanism; the intermittent composite mechanism is located downstream of the first material strip traction mechanism and is arranged adjacent to the material strip traction mechanism; the second material strip traction mechanism is located downstream of the intermittent composite mechanism.

[0014] Furthermore, a tension control mechanism is provided between the winding mechanism and the second material strip traction mechanism.

[0015] Furthermore, the first material strip traction mechanism includes a pair of traction rollers arranged opposite to each other, and the single-pole sheet passes through the gap between the two traction rollers.

[0016] Furthermore, the second material strip traction mechanism is a vacuum traction roller.

[0017] Furthermore, the intermittent composite mechanism includes a pair of pressing rollers, and the composite pole piece and the single pole piece pass through the gap between the two pressing rollers.

[0018] As can be seen from the above technical solution, the present invention controls the pulling speed of the single-pole sheet and the overall composite sheet, making the pulling speed of the single-pole sheet greater than that of the overall composite sheet during the non-composite period. This adjusts the compensation value of the inner and outer electrode sheet lengths, improves the winding quality of the battery cell, and alleviates battery quality issues caused by the different expansion rates of the positive and negative electrode sheets. Furthermore, adjusting the pulling speed allows for flexible adjustment of the compensation length of the single-pole sheet, adapting to different battery models and sizes, and providing compatibility with a wide range of batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 A schematic diagram of the structure of an overall composite sheet formed by combining a composite electrode sheet and a single electrode sheet;

[0021] Figure 2 A simplified structural diagram of a winding device used in a winding method according to an embodiment of the present invention;

[0022] Figure 3 Schematic diagram of the status of single pole piece and composite pole piece in the non-composite time period.

[0023] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings. DETAILED DESCRIPTION

[0024] The present invention is described in detail below in conjunction with the accompanying drawings. When describing the embodiments of the present invention in detail, for the convenience of explanation, the drawings showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. It should be noted that the drawings are simplified and all use non-precise scales, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. At the same time, in the description of this application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features; the terms "positive", "negative", "bottom", "upper", "lower", etc. indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0025] Figure 1 The figure is a schematic diagram of the structure of the overall composite sheet after the composite electrode and the single electrode are combined together. Figure 1 As shown, the integrated composite sheet includes a composite electrode sheet 20 and a unipolar sheet 10. The unipolar sheet 10 is a conventional electrode sheet, i.e., one with an active material coated on a current collector. The composite electrode sheet 20 is a composite structure formed by covering the surface of a conventional electrode sheet 20b with a separator 20a. The separator 20a and the conventional electrode sheet 20b can be combined to form an integrated structure through a pressing process such as hot pressing. The composite electrode sheet of this embodiment is a composite structure consisting of a negative electrode sheet and a separator, with the separator covering both surfaces of the negative electrode sheet. The unipolar sheet 10 is the positive electrode sheet.

[0026] like Figure 2 As shown, the battery cell winding equipment used in the winding method of this embodiment includes a single-pole sheet unwinding mechanism 1, a composite electrode sheet unwinding mechanism 2, a first material strip traction mechanism 3, a second material strip traction mechanism 4, an intermittent composite mechanism 5, a tension control mechanism 6 and a winding mechanism 7.

[0027] The single-pole sheet unwinding mechanism 1 is used to output the single-pole sheet 10. The single-pole sheet roll is installed at the single-pole sheet unwinding mechanism 1. The single-pole sheet unwinding mechanism 1 outputs the single-pole sheet outward by rotating the roll. The composite electrode sheet unwinding mechanism 2 is used to output the composite electrode sheet 20. The diaphragm and the conventional electrode sheet can be compounded together at other stations to form a roll. The roll is installed at the composite electrode sheet unwinding mechanism 2, and the composite electrode sheet is output outward by the composite electrode sheet unwinding mechanism 2. In this embodiment, the composite electrode sheet has been compounded and made into a roll at other stations. In other embodiments, the composite electrode sheet can also be directly output after the diaphragm and the conventional electrode sheet are compounded on site by the compounding device on the battery cell winding equipment. In this case, the compounding device is equivalent to the composite electrode sheet unwinding mechanism 2. The specific structure of the compounding device for compounding composite electrode sheets can refer to the structure of the first compounding device disclosed in the Chinese invention patent application No. 2023114421908. The structure of the compounding device can also be the structure of other existing winding equipment, as long as the diaphragm and the conventional electrode sheet can be compounded together.

[0028] The first material strip pulling mechanism 3 of this embodiment includes a pair of opposing pulling rollers, with the monopole sheet 10 passing through the gap between the two pulling rollers. The first material strip pulling mechanism 3 is disposed downstream of the monopole sheet unwinding mechanism 1 and is used to pull the monopole sheet 10. The pulling speed of the monopole sheet 10 can be controlled by the first material strip pulling mechanism 3.

[0029] The intermittent composite mechanism 5 is arranged downstream of the first material strip pulling mechanism 3, and the intermittent composite mechanism 5 and the first material strip pulling mechanism 3 are arranged adjacent to each other, and the single pole piece 10 and the composite pole piece 20 are composited together at the intermittent composite mechanism 5. The first material strip pulling mechanism 3 is close to the intermittent composite mechanism 5, and the two are arranged adjacent to each other, which can accurately control the compensation length of the single pole piece. The intermittent composite mechanism 5 uses an intermittent composite method to composite the composite pole piece 20 and the single pole piece 10 together to form an integral composite piece. The intermittent composite mechanism 5 has a composite time period and a non-composite time period when it is working. During the composite time period, the intermittent composite mechanism 5 presses the composite pole piece 20 and the single pole piece 10 together to form a composite section A on the integral composite piece (see Figure 1 During the non-combination period, the intermittent recombination mechanism 5 does not perform any operation on the composite electrode sheet 20 and the single-pole sheet 10, thereby forming an uncombined segment B on the overall composite sheet, where the composite electrode sheet 20 and the single-pole sheet 10 are separated from each other. On the overall composite sheet, the composite segments A and the uncombined segments B are arranged alternately, with one composite segment A followed by an uncombined segment B, and another uncombined segment B followed by a composite segment A, and this process repeats.

[0030] The intermittent lamination mechanism 5 may be a thermal lamination mechanism that laminates the composite electrode sheet 20 and the monopole sheet 10 together through hot pressing. Because the diaphragm in the composite electrode sheet 20 itself is also viscous, in some embodiments, the intermittent lamination mechanism 5 may be a pressure lamination mechanism that laminates the composite electrode sheet 20 and the monopole sheet 10 together through pressure. The intermittent lamination mechanism 5 of this embodiment includes a pair of opposing hot pressing rollers. The composite electrode sheet 20 and the monopole sheet 10 pass through the gap between the hot pressing rollers. When the two hot pressing rollers are pressed together, the composite electrode sheet 20 and the monopole sheet 10 are laminated together to form a composite segment A.

[0031] The second material belt pulling mechanism 4 is disposed downstream of the intermittent laminating mechanism 5. The second material belt pulling mechanism 4 is used to pull the entire composite sheet. The pulling speed of the entire composite sheet can be controlled by the second material belt pulling mechanism 4. In this embodiment, the second material belt pulling mechanism 4 is a vacuum pulling roller. The second material belt pulling mechanism 4 is disposed downstream of the intermittent laminating mechanism 5. By pulling the entire composite sheet, it can pull the composite electrode sheet 20. At the same time, it does not affect the feeding of the single-pole sheet 10 by the first material belt pulling mechanism 3, allowing the first material belt pulling mechanism 3 to accurately control the length compensation value of the single-pole sheet 10.

[0032] Tension control mechanism 6 is located downstream of second strip pulling mechanism 4, between second strip pulling mechanism 4 and winding mechanism 7. Tension control mechanism 6 is used to adjust the tension of the composite sheet. The structure of tension control mechanism 6 of the present invention is similar to that of tension control mechanisms in conventional battery cell winding equipment.

[0033] The whole composite sheet is sent to the winding mechanism 7 after passing through the tension control mechanism 6, and is wound by the winding needle of the winding mechanism 7 to form a battery core.

[0034] The battery cell winding equipment of the present invention also includes a correction mechanism, a buffer roller, a cutter mechanism, etc. The structures of these mechanisms are the same as the existing structures in the existing battery cell winding equipment and can be set accordingly as needed. The present invention does not improve these mechanisms and will not be elaborated here.

[0035] The following combination Figure 2 and Figure 3 , the specific steps of the battery cell winding method of the present application are described. The battery cell winding method of the present invention includes the following steps:

[0036] The single-pole sheet unwinding mechanism 1 and the composite pole sheet unwinding mechanism 2 output the single-pole sheet 10 and the composite pole sheet 20 respectively. The single-pole sheet 10 is pulled by the first material belt pulling mechanism 3, and the second material belt pulling mechanism 4 pulls the entire composite sheet.

[0037] The single pole piece 10 and the composite pole piece 20 are intermittently composited at the intermittent composite mechanism 5 to obtain an integral composite piece;

[0038] The whole composite sheet is wound at the winding mechanism 7 to form a battery core;

[0039] The process of the intermittent composite mechanism 5 composites the single pole piece 10 and the composite pole piece 20 includes a composite time period and a non-composite time period. In the composite time period, the traction speed of the first material belt traction mechanism 3 and the traction speed of the second material belt traction mechanism 4 are the same. The intermittent composite mechanism 5 composites the composite pole piece 20 and the single pole piece 10 (see Figure 2 ), forming a composite section A on the overall composite sheet; in the non-composite time period, the traction speed of the first material belt traction mechanism 3 is greater than the traction speed of the second material belt traction mechanism 4, such as Figure 3 As shown, when the pulling speed of the first material belt pulling mechanism 3 is greater than the pulling speed of the second material belt pulling mechanism 4, the length of the single-pole sheet 10 sent to the intermittent compounding mechanism 5 during the non-compounding time period is slightly longer than the length of the composite electrode sheet 20, thereby achieving length compensation of the single-pole sheet. During the non-compounding time period, the intermittent compounding mechanism 5 does not compound the single-pole sheet 10 and the composite electrode sheet 20. The single-pole sheet 10 and the composite electrode sheet 20 are separated from each other, forming an uncompounded section B on the overall composite sheet. During the non-compounding time period, the pulling speed difference is adjusted according to the required length compensation value. The length compensation value = pulling speed difference × the length of the non-compounding time period. The pulling speed difference = pulling speed of the first material belt pulling mechanism - pulling speed of the second material belt pulling mechanism. The length compensation value is set according to production requirements. The length compensation value of battery cells of different sizes and models is different, and is not limited here.

[0040] By controlling the pulling speeds of the first and second pulling mechanisms, the present invention adjusts the compensation value for the inner and outer electrode lengths, thereby improving battery quality issues caused by the different expansion rates of the positive and negative electrode sheets. Furthermore, adjusting the pulling speed allows for flexible adjustment of the compensation length of each electrode sheet, adapting to batteries of different models and sizes, and providing wide compatibility.

[0041] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is to be construed in the widest manner consistent with the principles and novel features disclosed herein.

Claims

1. A battery core winding method, characterized in that: The composite electrode sheet and the single electrode sheet are wound into a battery cell using a battery cell winding device, wherein the battery cell winding device includes a single electrode sheet unwinding mechanism, a composite electrode sheet unwinding mechanism, a first material strip pulling mechanism, a second material strip pulling mechanism, an intermittent compounding mechanism, and a winding mechanism; The battery core winding method comprises the following steps: The single pole piece unwinding mechanism outputs the single pole piece, and the composite pole piece unwinding mechanism outputs the composite pole piece; The single-pole sheet and the composite pole sheet are intermittently composited at the intermittent composite mechanism to obtain an integral composite sheet; the single-pole sheet is pulled by the first material belt traction mechanism, and the integral composite sheet is pulled by the second material belt traction mechanism; the process of the intermittent composite mechanism compounding the single-pole sheet and the composite pole sheet includes a compounding time period and a non-compounding time period, in which the traction speed of the first material belt traction mechanism is the same as the traction speed of the second material belt traction mechanism, and the intermittent composite mechanism compounds the composite pole sheet and the single-pole sheet together, in the non-compounding time period, the traction speed of the first material belt traction mechanism is greater than the traction speed of the second material belt traction mechanism, and the intermittent composite mechanism does not compound the single-pole sheet and the composite pole sheet; in the non-compounding time period, the traction speed difference is adjusted according to the required length compensation value, the traction speed difference = the traction speed of the first material belt traction mechanism - the traction speed of the second material belt traction mechanism, and the length compensation value = the traction speed difference × the duration of the non-compounding time period; The integral composite sheet is wound at the winding mechanism to form a battery core.

2. The battery core winding method according to claim 1, wherein: The composite electrode sheet includes a negative electrode sheet and a separator composited on both sides of the negative electrode sheet, and the single electrode sheet is a positive electrode sheet; Alternatively, the composite electrode sheet includes a positive electrode sheet and a separator composited on both sides of the positive electrode sheet, and the single electrode sheet is a negative electrode sheet.

3. The battery core winding method according to claim 1, wherein: The first material strip traction mechanism is located downstream of the single-pole sheet unwinding mechanism; the intermittent composite mechanism is located downstream of the first material strip traction mechanism and is arranged adjacent to the first material strip traction mechanism; the second material strip traction mechanism is located downstream of the intermittent composite mechanism.

4. The battery core winding method according to claim 1, wherein: A tension control mechanism is provided between the winding mechanism and the second material strip traction mechanism.

5. The battery core winding method according to claim 1, wherein: The first material strip traction mechanism includes a pair of traction rollers arranged opposite to each other, and the monopole sheet passes through the gap between the two traction rollers.

6. The battery core winding method according to claim 1, wherein: The second material belt traction mechanism is a vacuum traction roller.

7. The battery core winding method according to claim 1, wherein: The intermittent composite mechanism includes a pair of pressing rollers, and the composite pole piece and the single pole piece pass through the gap between the two pressing rollers.

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