Battery and manufacturing method thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HUIZHOU EVE POWER CO LTD
- Filing Date
- 2026-02-02
- Publication Date
- 2026-04-21
Smart Images
Figure CN121905931A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of battery technology, and in particular to a battery and a method for manufacturing the same. Background Technology
[0002] In the production process of wound batteries, negative electrode, separator, positive electrode, and another separator are stacked sequentially. By applying winding tension to both ends of the stacked multilayer electrodes and separators using a winding machine, the multilayer electrodes and separators can be wound into a battery cell. However, after winding is completed, the winding tension at the end of the winding is removed as the electrode is cut, which can easily lead to poor adhesion of the outermost electrode covering the winding structure. Consequently, in subsequent formation and aging processes, gas can easily accumulate at the poorly adhered locations, resulting in defects such as uneven lithium intercalation, lithium plating, and bubble spots. Summary of the Invention
[0003] This application provides a battery and a method for manufacturing the same.
[0004] The battery according to the embodiments of this application includes a cell assembly, which includes a first electrode, a first separator, a second electrode, and a second separator that are sequentially stacked and wound relative to a winding center. The first electrode covers the second electrode at the winding tail end, and one of the first separator and the second separator covers the first electrode at the winding tail end. At the winding tail end, the distance A of the first electrode extending beyond the second electrode is greater than or equal to a first preset distance D1; and / or, the distance B of the first separator and the second separator covering the first electrode is greater than or equal to a second preset distance D2.
[0005] In the battery of this application embodiment, the distance A of the first electrode extending beyond the second electrode at the winding tail end is greater than or equal to a first preset distance D1, so that the portion of the first electrode that lacks tension and is difficult to fit tightly at the winding tail end extends beyond the area where the first electrode and the second electrode are opposite; and / or, at the winding tail end, the distance B of one of the first and second separators covering the first electrode extending beyond the first electrode is greater than or equal to a second preset distance D2, so that the first electrode can also be subjected to the winding tension of the outer separator and fit tightly with the inner separator and the first electrode at the winding tail end. Thus, the cell assembly can fit tightly in the area where the first electrode and the second electrode are opposite and the electrochemical reaction occurs, solving the problems of uneven lithium intercalation, lithium plating, bubble spots and other defects caused by gas accumulation at poor bonding locations.
[0006] In some implementations, the first preset distance D1 satisfies: D1≥5mm.
[0007] In this way, the part of the first electrode that lacks tension at the winding end extends beyond the area where the first and second electrodes are opposite each other, while the area where the first and second electrodes are opposite each other and generate an electrochemical reaction can be tightly bonded, reducing the risk of defects such as uneven lithium intercalation, lithium plating, and bubble spots caused by poor bonding.
[0008] In some embodiments, when the battery cell assembly is in a flattened state, the first electrode includes a first region and a second region. The first region overlaps with the second electrode, and the second region is offset from the second electrode in the length direction of the second electrode. On one side of the battery cell assembly, a winding tail end is formed. The distance A between the end of the second region and the end of the second electrode is greater than or equal to a first preset distance D1.
[0009] In this way, an electrochemical reaction can occur between the first region and the second electrode to achieve the charging and discharging of the battery. The second region is offset from the second electrode, so even if the second region has poor adhesion after the winding tension is removed, it can avoid defects such as gas accumulation, uneven lithium intercalation, lithium plating, and bubble spots that may occur due to the electrochemical reaction of the positive and negative electrodes.
[0010] In some embodiments, the winding tail of one of the first diaphragm and the second diaphragm is located on the outermost layer of the cell assembly winding structure and covers the second region.
[0011] Thus, by covering the second region at the winding tail end with the first and second diaphragms, the first electrode sheet is prevented from being exposed, thereby providing protection.
[0012] In some implementations, the second preset distance D2 satisfies: D2≥5mm.
[0013] Thus, by having one of the first diaphragm and the second diaphragm covering the first electrode sheet, the distance B beyond the first electrode sheet is greater than or equal to the second preset distance D2, and the second preset distance D2 is greater than or equal to 5mm, thereby generating a certain winding tension in the first diaphragm (or the second diaphragm) covering the first electrode sheet at the winding tail end, tightly wrapping the first electrode sheet and the second electrode sheet at the winding tail end.
[0014] In some embodiments, when the cell assembly is in a flattened state, one of the first diaphragm and the second diaphragm covering the first electrode includes a third region and a fourth region. The third region overlaps with the first electrode, and the fourth region is offset from the first electrode in the length direction of the first electrode and forms a wound tail end on one side of the cell assembly. The distance B between the end of the fourth region and the end of the first electrode is greater than or equal to a second preset distance D2.
[0015] Thus, since the end of the fourth region extends far beyond the end of the first electrode, even if the winding tail of the fourth region does not fit well after the winding tension of the winding machine is removed, the third region and the first electrode can still fit tightly together.
[0016] In some implementations, the fourth region is located on the outermost layer of the cell assembly winding structure in the wound state.
[0017] In this way, the diaphragm in the fourth region can provide sufficient insulation protection for the battery cell assembly.
[0018] In some embodiments, on the side of the cell assembly corresponding to the winding tail end, the distance B between the end of the fourth region and the end of the first electrode is greater than or equal to a second preset distance D2, and the distance A between the end of the first electrode and the end of the second electrode is greater than or equal to a first preset distance D1, wherein the first preset distance D1 satisfies: D1≥5mm.
[0019] Thus, the outermost first or second diaphragm can provide a certain winding tension, so that the first electrode and the second electrode are in contact, while ensuring that the part of the first electrode that forms the winding tail and is prone to losing tension is offset by a large distance from the second electrode, and the area where the first electrode and the second electrode are opposite can be tightly wound.
[0020] In some embodiments, on the side of the cell assembly corresponding to the winding tail end, the distance B between the end of the fourth region and the end of the first electrode is greater than or equal to a second preset distance D2, and the end of the first electrode extends beyond the end of the second electrode, and the distance between the end of the first electrode and the end of the second electrode is less than the second preset distance D2.
[0021] In this way, the outermost first or second diaphragm can provide a certain winding tension, so that the first and second electrodes can be attached together, while the second electrode can overlap with the first electrode as much as possible, and the structural and material redundancy can be reduced.
[0022] In some implementations, when the cell assembly is in a flattened state, on the side of the cell assembly corresponding to the winding center, the distance between the end of the first electrode and the end of the second electrode is less than the distance A by which the first electrode extends beyond the second electrode at the winding tail end. Both the first diaphragm and the second diaphragm extend beyond the ends of the first electrode and the second electrode, and the maximum distance between the ends of the first diaphragm and the two ends of the first electrode and the second electrode is less than the distance B by which the first electrode is extended beyond the first diaphragm or the second diaphragm at the winding tail end.
[0023] In this way, the second electrode can overlap with the first electrode as much as possible, and the first and second diaphragms can play a sufficient protective role, while reducing structural and material redundancy.
[0024] The battery manufacturing method of this application is used to manufacture a battery. The battery includes a cell assembly. The cell assembly includes a first electrode, a first separator, a second electrode, and a second separator that are sequentially stacked and wound relative to a winding center. The first electrode covers the second electrode at the winding tail end, and one of the first separator and the second separator covers the first electrode at the winding tail end. The battery manufacturing method includes: Confirm the first preset distance D1 and / or the second preset distance D2; Cut the winding tail end of the battery cell assembly so that the distance between the first electrode and the second electrode is greater than or equal to a first preset distance D1; and / or so that the distance between the first diaphragm and the second diaphragm covering the first electrode and the distance between them is greater than or equal to a second preset distance D2.
[0025] Thus, by ensuring that the distance between the first electrode and the second electrode at the winding end is greater than or equal to a first preset distance D1; and / or that the distance between the first diaphragm and the second diaphragm covering the first electrode is greater than or equal to a second preset distance D2, the areas of the first electrode and the second electrode can fit tightly together, thereby reducing the risks of gas accumulation, uneven lithium intercalation, lithium plating, bubble spots, etc.
[0026] In some embodiments, the battery manufacturing method further includes: The first and second electrode sheets are wound using a winding machine; The winding tail end of the second electrode sheet is first cut using a cutting machine; After the second electrode is wound at the winding tail end, the cutting position of the first electrode at the winding tail end is confirmed so that the dimension between the position of the outermost layer of the first electrode wound on the winding needle and the cutting position is greater than or equal to the first preset distance D1. The first electrode is cut at the cutting position.
[0027] Thus, when the winding end of the first electrode is cut, the winding end of the second electrode is already wound on the winding needle and covered by the outermost layer of the first electrode wound on the winding needle. This ensures that the opposing portions of the first and second electrodes have a certain winding tension, allowing for a tight fit and reducing the risk of uneven lithium intercalation, lithium plating, and bubble spots. The distance A between the winding end of the first electrode (i.e., the cutting position) and the winding end of the second electrode is greater than or equal to the dimension between the cutting position and the position where the outermost layer of the first electrode is wound on the winding needle when it is cut. This ensures that the distance A is greater than or equal to the first preset distance D1 and facilitates operation.
[0028] In some embodiments, the battery manufacturing method further includes: Collect defective battery cells and assemblies that have already been manufactured; Measure and count the length of the defective area at the winding tail end of multiple defective products, and determine the first preset distance D1 or the second preset distance D2 based on the length of the defective area.
[0029] In this way, the distance between the first electrode and the second electrode is greater than the defect length of previous defective products, or the distance between the outermost first diaphragm or second diaphragm and the first electrode is greater than the defect length of existing defective products, thereby reducing the influence of the first electrode or adhesive film portion that is prone to losing winding tension, and ensuring that the inner second electrode and the first electrode are tightly bonded.
[0030] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description
[0031] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, wherein: Figure 1 This is a schematic diagram of the battery structure at the beginning of winding according to the embodiments of this application; Figure 2 This is a schematic diagram of the structure of the battery according to an embodiment of this application, after the first electrode sheet is cut after winding; Figure 3 This is a schematic diagram of the battery cell assembly according to an embodiment of this application in a flattened state; Figure 4 This is a schematic diagram of the structure of a battery cell assembly in a flattened state, based on existing technology. Figure 5 This is a schematic diagram of the battery cell assembly in a flattened state according to another embodiment of this application; Figure 6 This is a flowchart of a battery manufacturing method according to an embodiment of this application.
[0032] Explanation of reference numerals in the attached figures: 100-Battery, 10-Cell assembly, 11-First electrode, 111-First region, 112-Second region, 113-Tangent position, 12-First separator, 123-Third region, 124-Fourth region, 13-Second electrode, 14-Second separator, 101-Wound tail end, 102-Wound center, 30-Defective product, 31-Defect, 200-Winding needle. Detailed Implementation
[0033] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.
[0034] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.
[0035] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.
[0036] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.
[0037] The following disclosure provides many different embodiments or examples for implementing different structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.
[0038] The battery 100 in this application embodiment can be a battery cell, and the battery cell can be a secondary battery 100. The secondary battery 100 refers to a type of battery cell that can be used repeatedly through charging and discharging. For example, the battery cell can be a lithium-ion battery 100, a sodium-ion battery 100, a magnesium-ion battery 100, a lithium-sulfur battery 100, a nickel-metal hydride battery 100, etc.
[0039] The battery 100 in this embodiment can also be a battery device, which includes one or more battery cells, which can be connected in series, parallel, or mixed. In the case where the battery device includes multiple battery cells, at least one of the battery cells has the cell assembly 10 of this embodiment.
[0040] Please see Figures 1-3 The battery 100 of this application includes a cell assembly 10. The cell assembly 10 includes a first electrode 11, a first separator 12, a second electrode 13, and a second separator 14, which are stacked and wound relative to a winding center 102 in sequence. The first electrode 11 covers the second electrode 13 at the winding tail end 101. One of the first separator 12 and the second separator 14 covers the first electrode 11 at the winding tail end 101. At the winding tail end 101, the distance A of the first electrode 11 beyond the second electrode 13 is greater than or equal to a first preset distance D1. And / or, the distance B of the first separator 12 and the second separator 14 covering the first electrode 11 is greater than or equal to a second preset distance D2.
[0041] In the battery 100 of this application embodiment, the distance A of the first electrode 11 extending beyond the second electrode 13 at the winding tail end 101 is greater than or equal to a first preset distance D1, so that the portion of the first electrode 11 that lacks tension and is difficult to fit tightly at the winding tail end 101 extends beyond the area where the first electrode 11 and the second electrode 13 are opposite; and / or, at the winding tail end 101, the distance B of the first separator 12 and the second separator 14 covering the first electrode 11 extending beyond the first electrode 11 is greater than or equal to a second preset distance D2, so that the first electrode 11 can also be subjected to the winding tension of the outer separator at the winding tail end 101 and fit tightly with the inner separator and the first electrode 11. Thus, the cell assembly 10 can fit tightly in the area where the first electrode 11 and the second electrode 13 are opposite and an electrochemical reaction occurs, solving the problems of uneven lithium intercalation, lithium plating, bubble spots and other defects caused by gas accumulation at poor fitting locations.
[0042] Specifically, the battery cell assembly 10 can be a cylindrical or flat wound structure. For ease of winding, the first electrode 11, the first separator 12, the second electrode 13, and the second separator 14 are all long rectangular sheets. During the manufacturing process of the battery 100, the first electrode 11, the first separator 12, the second electrode 13, and the second separator 14 can be wound using a winding machine. The first electrode 11, the first separator 12, the second electrode 13, and the second separator 14 are stacked and wound around the winding needle 200 of the winding machine as the winding center 102.
[0043] One of the first electrode 11 and the second electrode 13 is a negative electrode, and the other is a positive electrode. For example, the first electrode 11 is a negative electrode. The negative electrode (first electrode 11) extends beyond the positive electrode (second electrode 13) at the winding end 101 and covers the positive electrode, so that the more chemically active positive electrode material is not easily exposed.
[0044] It should be noted that the first electrode 11 covering the second electrode 13 means that the winding end 101 of the first electrode 11 can cover the winding end 101 of the second electrode 13, and the first electrode 11 and the second electrode 13 are separated by the first diaphragm 12, rather than the first electrode 11 directly contacting and wrapping the second electrode 13.
[0045] The distance A of the first electrode 11 extending beyond the second electrode 13 refers to the distance between the edge of the first electrode 11 and the edge of the second electrode 13 on the side corresponding to the formation of the winding tail end 101 when the cell assembly 10 is in a flattened state. Similarly, the distance by which one of the first separator 12 and the second separator 14 extends beyond the first electrode 11 refers to the distance between the edge of the first separator 12 or the second separator 14 that covers the first electrode 11 and the edge of the first electrode 11 when the cell assembly 10 is in a flattened state.
[0046] In some embodiments, such as Figure 2 As shown, the first preset distance D1 can be determined based on the distance between the position of the outermost layer of the first electrode 11 wound on the winding needle 200 when the first electrode 11 is cut, and the position where the winding tail 101 of the first electrode 11 is cut off. The position of the outermost layer of the first electrode 11 wound on the winding needle 200 when the first electrode 11 is cut off refers to the position where the outermost layer of the first electrode 11 is tangent to the spool formed by the first electrode 11, the diaphragm, and the second electrode 12 already wound on the winding needle 200. For ease of explanation, this position is marked as the tangent position 113 in the following description and figures.
[0047] In other embodiments, such as Figure 4 As shown, the first preset distance D1 or the second preset distance D2 can be the length of the area where defects occur at the winding tail end 101 of the cell assembly 10 in the flattened state of the wound battery, in the wound type battery with defects such as uneven lithium intercalation, lithium plating, and bubble spots.
[0048] Please see Figures 2-4 In some implementations, the first preset distance D1 satisfies: D1≥5mm.
[0049] In this way, the portion of the first electrode 11 lacking tension at the winding end 101 extends beyond the area where the first electrode 11 and the second electrode 13 are opposite each other, while the areas where the first electrode 11 and the second electrode 13 are opposite each other and generate an electrochemical reaction can be tightly bonded, reducing the risk of defects such as uneven lithium intercalation, lithium plating, and bubble spots caused by poor bonding.
[0050] In this embodiment, the distance A between the first electrode 11 and the second electrode 13 and the first preset distance D1 satisfy: A≥D1≥5mm.
[0051] Specifically, such as Figure 2 and Figure 3 As shown, the first preset distance D1 can be the distance between the winding center 102 and the position where the first electrode 11 is cut off at the winding tail end 101 in the winding machine used to wind the battery cell assembly 10. For example, the first preset distance D1 can be 5mm, 6mm, 7.5mm, 9mm, 11mm, 16mm, 20mm, etc. Further, the first preset distance D1 can be less than 40mm.
[0052] like Figure 3 and Figure 4 As shown, the first preset distance D1 can also be the length of the defective area at the winding tail end in existing defective products. Combined with... Figure 2When the first electrode 11 is cut, if the distance between the outermost layer of the first electrode 11 wound on the winding needle 200 (tangential position 113) and the position where the first electrode 11 is cut at the winding end 101 is large, for example, when the distance between the tangential position 113 and the position where the first electrode 11 is cut at the winding end 101 is greater than 35mm, a first preset distance D1 can be determined based on the length of the defective area in existing defective products. For example, the first preset distance D1 can be 5mm, 5.5mm, 8mm, 10mm, 13mm, 19mm, etc.
[0053] Taking the first preset distance D1 as 5mm as an example, the distance A of the first electrode 11 beyond the second electrode 13 can be 5mm, 5.1mm, 4.8mm, 7mm, 16mm, etc.
[0054] Please see Figures 1-3 In some embodiments, when the cell assembly 10 is in a flattened state, the first electrode 11 includes a first region 111 and a second region 112. The first region 111 overlaps with the second electrode 13, and the second region 112 is offset from the second electrode 13 in the length direction of the second electrode 13. It is also formed on one side of the cell assembly 10 corresponding to the winding tail end 101. The distance A between the edge of the second region 112 and the edge of the second electrode 13 is greater than or equal to a first preset distance D1.
[0055] In this way, an electrochemical reaction can occur between the first region 111 and the second electrode 13 to achieve the charging and discharging of the battery 100. The second region 112 is offset from the second electrode 13. Even if the second region 112 has poor adhesion after the winding tension is removed, it can avoid defects such as gas accumulation, uneven lithium intercalation, lithium plating, and bubble spots that occur with the electrochemical reaction of the positive and negative electrodes.
[0056] Specifically, a first diaphragm 12 is spaced between the first region 111 and the second electrode 13. In the wound state, the first region 111, the first diaphragm 12, the second electrode 13, and the second diaphragm 14 are tightly wound and closely fitted. The end of the second region 112, which corresponds to the second region 112, forms one side edge of the wound tail 101, and the end of the second electrode 13, which corresponds to the second electrode 13, forms one side edge of the wound tail 101. The ends of the first region 112 and the second electrode 13 can both be straight edges, and the distance A between the end of the second region 112 and the end of the second electrode 13 can be the vertical distance between the two straight edges in the flattened state.
[0057] The edge of the second region 112 corresponding to the winding tail 101 is the position where the first electrode 11 is cut off. When the winding is finished and the first electrode 11 is cut off, the end of the second electrode 13 can be wound on the outer peripheral surface of the inner winding structure and covered by the first region 111.
[0058] In some embodiments, the winding tail 101 of one of the first diaphragm 12 and the second diaphragm 14 is located on the outermost layer of the winding structure of the cell assembly 10 and covers the second region 112.
[0059] Thus, by having the first diaphragm 12 and the second diaphragm 14 cover the second region 112 at the winding tail end 101, the first electrode 11 is prevented from being exposed, thus providing protection.
[0060] Specifically, the first electrode 11 can be a negative electrode, coated with a negative electrode active material, such as a carbon material, a silicon-based material, or a metal oxide. The second electrode 13 can be a positive electrode, coated with a positive electrode active material, such as a lithium-containing metal oxide. The first electrode 11 and the second electrode 13, the first separator 12 and the second separator 14 can be insulating films.
[0061] Please see Figure 4 and Figure 5 In some implementations, the second preset distance D2 satisfies: D2≥5mm.
[0062] Thus, by covering one of the first electrode 11 with the first diaphragm 12 and the second diaphragm 14, the distance B beyond the first electrode 11 is greater than or equal to the second preset distance D2, and the second preset distance D2 is greater than or equal to 5mm, so that the first diaphragm 12 (or the second diaphragm 14) covering the first electrode 11 at the winding tail end 101 can generate a certain winding tension, which tightly wraps the first electrode 11 and the second electrode 13 at the winding tail end 101.
[0063] In this embodiment, the first diaphragm 12 and the second diaphragm 14 cover one of the first electrode 11, and the distance B beyond the first electrode 11 and the second preset distance D2 satisfy: B≥D2≥5mm.
[0064] Specifically, the second preset distance D2 can be determined based on the length of the defective winding end in existing defective products. For example, the second preset distance D2 can be 5mm, 7mm, 15mm, 21mm, 23mm, 28mm, 30mm, etc. Taking the first diaphragm 12 covering the first electrode 11 and the second preset distance D2 being 5mm as an example, the distance B of the first diaphragm 12 extending beyond the first electrode 11 at the winding end 101 can be 5mm, 5.2mm, 6.3mm, 8mm, 13mm, 14mm, etc.
[0065] Please see Figure 5In some embodiments, when the cell assembly 10 is in a flattened state, one of the first separator 12 and the second separator 14 covering the first electrode 11 includes a third region 123 and a fourth region 124. The third region 123 overlaps with the first electrode 11, and the fourth region 124 is offset from the first electrode 11 along the length direction of the first electrode 11 and is formed on one side of the cell assembly 10 corresponding to the winding tail end 101. The distance B between the end of the fourth region 124 and the end of the first electrode 11 is greater than or equal to a second preset distance D2.
[0066] Thus, since the end of the fourth region 124 extends far beyond the end of the first electrode 11, even if the winding tail end 101 of the fourth region 124 does not fit well after the winding tension of the winding machine is removed, the third region 123 and the first electrode 11 can still fit tightly together.
[0067] Specifically, the end of the fourth region 124, that is, the fourth region 124, forms one side edge of the coiled tail 101, and the end of the first electrode 11, that is, the first electrode 11, forms one side edge of the coiled tail 101. The ends of the first region 112 and the first electrode 11 can both be straight edges, and the distance B between the end of the fourth region 124 and the end of the first electrode 11 can be the vertical distance between the two straight edges in the flattened state.
[0068] Taking the first diaphragm 12 covering the first electrode 11 at the winding tail end 101 as an example, the first diaphragm 12 includes a first region 111 that overlaps with the first electrode 11, and a fourth region 124 that is offset from the first electrode 11. In the flattened state, the projection of the fourth region 124 along the thickness direction is completely outside the projection area of the first electrode 11.
[0069] In some embodiments, the fourth region 124 is located on the outermost layer of the wound structure of the cell assembly 10 in the wound state. In this way, the separator of the fourth region 124 can provide sufficient insulation protection for the cell assembly 10.
[0070] Please see Figure 5 In some embodiments, on the side of the cell assembly 10 corresponding to the formation of the winding tail end 101, the distance B between the end of the fourth region 124 and the end of the first electrode 11 is greater than or equal to the second preset distance D2, and the distance A between the end of the first electrode 11 and the end of the second electrode 13 is greater than or equal to the first preset distance D1, wherein the first preset distance D1 satisfies: D1≥5mm.
[0071] Thus, the outermost first diaphragm 12 or second diaphragm 14 can provide a certain winding tension, so that the first electrode 11 and the second electrode 13 are in contact, while ensuring that the part of the first electrode 11 that forms the winding tail 101 and is prone to losing tension is offset by a large distance from the second electrode 13, and the area where the first electrode 11 and the second electrode 13 are opposite can be tightly wound.
[0072] Specifically, the first preset distance D1 can be the distance between the winding center 102 and the cutting position of the first electrode 11, or it can be the length of the defective area at the winding end in an existing defective product. For example, if both the first preset distance D1 and the second preset distance D2 are 5mm, the distance A between the end of the first electrode 11 and the end of the second electrode 13, and the distance B between the end of the fourth region 124 and the end of the first electrode 11, can both be equal to 5mm. Alternatively, if the first preset distance D1 is 10mm, the distance A between the end of the first electrode 11 and the end of the second electrode 13 can be 10mm, 12mm, 15mm, 16mm, etc.; and if the second preset distance D2 is 12mm, the distance B between the edge of the fourth region 124 and the edge of the first electrode 11 can be 12mm, 13mm, 15mm, 20mm, etc.
[0073] In some embodiments, on the side of the cell assembly 10 corresponding to the formation of the winding tail end 101, the distance B between the end of the fourth region 124 and the end of the first electrode 11 is greater than or equal to a second preset distance D2, the end of the first electrode 11 extends beyond the end of the second electrode 13, and the distance between the end of the first electrode 11 and the end of the second electrode 13 is less than the second preset distance D2.
[0074] Thus, the outermost first diaphragm 12 or second diaphragm 14 can provide a certain winding tension, so that the first electrode 11 and the second electrode 13 can be attached together, and the second electrode 13 can overlap with the first electrode 11 as much as possible, thereby reducing structural and material redundancy.
[0075] In this embodiment, the distance between the end of the first electrode 11 and the end of the second electrode 13 is less than the distance B between the end of the fourth region 124 and the end of the first electrode 11. For example, if the second preset distance D2 is determined to be 6mm based on the length of the defective region in the defective product, then the distance B between the end of the fourth region 124 and the end of the first electrode 11 is greater than or equal to 6mm, and the distance between the end of the first electrode 11 and the end of the second electrode 13 is less than 5mm.
[0076] Please see Figure 3 and Figure 5In some embodiments, when the cell assembly 10 is in a flattened state, on the side of the cell assembly 10 corresponding to the formation of the winding center 102, the distance between the end of the first electrode 11 and the end of the second electrode 13 is less than the distance A by which the first electrode 11 extends beyond the second electrode 13 at the winding tail end 101. Both the first diaphragm 12 and the second diaphragm 14 extend beyond the ends of the first electrode 11 and the second electrode 13, and the maximum distance between the ends of the first diaphragm 12 and the second diaphragm 14 and the two ends of the first electrode 11 and the second electrode 12 is less than the distance B by which the first electrode 11 is extended beyond the first diaphragm 12 or the second diaphragm 14 at the winding tail end 101.
[0077] In this way, the second electrode 13 can overlap with the first electrode 11 as much as possible, and the first diaphragm 12 and the second diaphragm 14 can play a sufficient protective role, while reducing structural and material redundancy.
[0078] Specifically, in the flattened state, the first electrode 11, the first diaphragm 12, the second electrode 13, and the second diaphragm 14, corresponding to one end forming the winding center 102, first contact the winding needle 200 of the winding machine and are wound on the innermost side. The edge of the first electrode 11 on this side may extend beyond the edge of the second electrode 13 on the same side, and the edges of the first diaphragm 12 and the second diaphragm 14 on this side may both extend beyond the edge of the first electrode 11 on the same side. For example, the range of the first preset distance D1 and the second preset distance D2 is both greater than or equal to 5mm. On the side of the cell assembly 10 corresponding to the winding center 102, the distance A of the first electrode 11 extending beyond the second electrode 13 is less than 5mm, and the distance of the edges of the first diaphragm 12 and the second diaphragm 14 extending beyond the first electrode 11 is also less than 5mm.
[0079] Please see Figure 5 and Figure 6 The battery 100 manufacturing method of this application is used to manufacture a battery 100. The battery 100 includes a cell assembly 10. The cell assembly 10 includes a first electrode 11, a first separator 12, a second electrode 13, and a second separator 14 that are sequentially stacked and wound relative to a winding center 102. The first electrode 11 covers the second electrode 13 at the winding tail end 101. One of the first separator 12 and the second separator 14 covers the first electrode 11 at the winding tail end 101. The battery 100 manufacturing method includes: Step S10: Confirm the first preset distance D1 and / or the second preset distance D2; Step S20: Cut off the winding tail end 101 of the cell assembly 10 so that the distance A of the first electrode 11 beyond the second electrode 13 is greater than or equal to the first preset distance D1; and / or so that the distance B of the first diaphragm 12 and the second diaphragm 14 covering the first electrode 11 is greater than or equal to the second preset distance D2.
[0080] Thus, by winding the tail end 101, the distance A of the first electrode 11 extending beyond the second electrode 13 is greater than or equal to the first preset distance D1; and / or, the distance B of the first diaphragm 12 and the second diaphragm 14 covering the first electrode 11 is greater than or equal to the second preset distance D2, so that the areas of the first electrode 11 and the second electrode 13 can fit tightly together, thereby reducing the risk of gas accumulation, uneven lithium intercalation, lithium plating, bubble spots, etc.
[0081] In step S20, cutting off the winding tail end 101 of the cell assembly 10 means cutting off the first electrode 11, the first separator 12, the second electrode 13 and the second separator 14, as well as other structures in the cell assembly 10 (such as another separator).
[0082] Please see Figure 2 In some embodiments, the battery manufacturing method further includes: The first electrode 11 and the second electrode 13 are wound using a winding machine (not shown in the figure); The winding tail end 101 of the second electrode 13 is first cut using a cutting machine (not shown in the figure); After the winding tail 101 of the second electrode 13 is completed, the cutting position of the winding tail 101 of the first electrode 11 is confirmed so that the dimension between the position of the outermost layer of the first electrode 11 wound on the winding needle 200 and the cutting position is greater than or equal to the first preset distance D1. The first electrode 11 is cut at the cutting position.
[0083] Thus, when the winding tail 101 of the first electrode 11 is cut, the winding tail 101 of the second electrode 13 is already wound on the winding needle 200 and covered by the outermost layer of the first electrode 11 wound on the winding needle 200, thereby ensuring that the part of the first electrode 11 that is opposite to the second electrode 13 has a certain winding tension and can fit tightly, thereby reducing the risk of uneven lithium intercalation, lithium plating, bubble spots, etc.
[0084] In addition, the distance A between the winding tail end 101 of the first electrode 11 (i.e., the cutting position) and the winding tail end 101 of the second electrode 13 is greater than or equal to the dimension between the cutting position and the position where the outermost layer of the first electrode is wound on the winding needle when it is cut (i.e., the tangent position 113), thereby ensuring that the distance A is greater than or equal to the first preset distance D1, and is easy to operate.
[0085] Specifically, the first electrode 11, the first diaphragm 12, the second electrode 13, and the second diaphragm 14, stacked sequentially, can be wound into a cylindrical or spool shape using a winding machine. The winding center 102 is also the central axis of the winding needle 200 of the winding machine. In the later stage of winding, the second electrode 13 is cut off first, and the first electrode 11 continues to be wound. When the distance between the outermost layer of the first electrode 11 wound on the winding needle 200 and the cutting position is greater than or equal to the first preset distance D1, the first electrode 11 is then cut off. As explained above, when confirming the cutting position of the winding tail end 101 of the first electrode 11, the position of the outermost layer of the first electrode 11 wound on the winding needle 200 refers to the tangent position 113 of the outermost layer of the first electrode 11 on the wound spool.
[0086] The first diaphragm 12 and the second diaphragm 14 can be cut at the same time as the first electrode 11 is cut, or they can be cut before or after the first electrode is cut. The cut positions of the first electrode 11, the first diaphragm 12, and the second diaphragm 14 can be staggered.
[0087] The position where the first electrode 11 is cut can be determined according to the specifications and dimensions of the battery 100 and the models of the winding and cutting machines that match the corresponding specifications.
[0088] Please see Figure 4 In some embodiments, the battery manufacturing method further includes: Collect 30 defective battery cell assemblies from the manufactured products; Measure and count the length of the area where defects 31 are generated at the winding tail end of multiple defective products 30, and determine the first preset distance D1 or the second preset distance D2 based on the length of the area where defects 31 are generated by the defective products 30.
[0089] In this way, the distance A of the first electrode 11 beyond the second electrode 13 is greater than the length of the area where the defect 31 occurs in the previous defective product 30, or the distance of the outermost first diaphragm 12 or second diaphragm 14 beyond the first electrode 11 is greater than the length of the area where the defect 31 occurs in the existing defective product 30, thereby reducing the influence of the first electrode 11 or the adhesive film portion that is prone to losing winding tension, and ensuring that the inner second electrode 13 is tightly attached to the first electrode 11.
[0090] Specifically, defective product 30 refers to a product in the prior art batteries that suffers from uneven lithium intercalation, lithium plating, or bubble spots due to poor adhesion between the first and second electrodes at the winding tail end. Defect 31 can manifest as lithium intercalation, lithium plating, bubble spots, etc. By measuring the length along the winding direction of the defective area on one side of the cell assembly corresponding to the winding tail end in the flattened state from a certain number of defective products, and by statistical methods for selection and calculation, a preset distance can be determined.
[0091] Optionally, combined Figure 3 and Figure 4 Based on the statistical length of the defects in the first and second electrodes at the winding tail end of the defective product, a first preset distance D1 can be obtained. At the winding tail end 101, the distance A of the first electrode 11 exceeding the second electrode 13 is greater than or equal to the first preset distance D1. Optionally, combined Figure 4 and Figure 5 The second preset distance D2 can be obtained based on the statistical length of the defects generated at the winding tail end of the first electrode and the second electrode in the defective product. The distance B of the first electrode 11 covered by the first diaphragm 12 and the second diaphragm 14 is greater than or equal to the second preset distance D2.
[0092] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with the described embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0093] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.
Claims
1. A battery, characterized in that, The battery includes a cell assembly, which includes a first electrode, a first separator, a second electrode, and a second separator that are sequentially stacked and wound relative to a winding center. The first electrode covers the second electrode at the winding tail end, and one of the first separator and the second separator covers the first electrode at the winding tail end. Wherein, at the winding tail end, the distance A of the first electrode extending beyond the second electrode is greater than or equal to a first preset distance D1; and / or, the distance B of the first electrode extending beyond the first electrode, which is either the first diaphragm or the second diaphragm, is greater than or equal to a second preset distance D2.
2. The battery according to claim 1, characterized in that, The first preset distance D1 satisfies: D1≥5mm.
3. The battery according to claim 2, characterized in that, When the cell assembly is in a flattened state, the first electrode includes a first region and a second region. The first region overlaps with the second electrode, and the second region is offset from the second electrode in the length direction of the second electrode. The second region is located on one side of the cell assembly corresponding to the winding tail end. The distance A between the end of the second region and the end of the second electrode is greater than or equal to the first preset distance D1.
4. The battery according to claim 3, characterized in that, The winding tail end of one of the first diaphragm and the second diaphragm is located on the outermost layer of the cell assembly winding structure and covers the second region.
5. The battery according to claim 1, characterized in that, The second preset distance D2 satisfies: D2≥5mm.
6. The battery according to claim 5, characterized in that, When the cell assembly is in a flattened state, one of the first diaphragm and the second diaphragm covering the first electrode includes a third region and a fourth region. The third region overlaps with the first electrode, and the fourth region is offset from the first electrode in the length direction of the first electrode and is located on the side of the cell assembly corresponding to the winding tail end. The distance B between the end of the fourth region and the end of the first electrode is greater than or equal to the second preset distance D2.
7. The battery according to claim 6, characterized in that, The fourth region is located on the outermost layer of the battery cell assembly winding structure in the wound state.
8. The battery according to claim 6, characterized in that, On the side of the cell assembly corresponding to the winding tail end, the distance A between the end of the first electrode and the end of the second electrode is greater than or equal to a first preset distance D1, wherein the first preset distance D1 satisfies: D1≥5mm.
9. The battery according to claim 6, characterized in that, On the side of the cell assembly corresponding to the winding tail end, the end of the first electrode extends beyond the end of the second electrode, and the distance A between the end of the first electrode and the end of the second electrode is less than the second preset distance D2.
10. The battery according to claim 1, characterized in that, When the battery cell assembly is in a flattened state, on the side of the battery cell assembly corresponding to the winding center, the distance between the end of the first electrode and the end of the second electrode is less than the distance A by which the first electrode extends beyond the second electrode at the winding tail end. Both the first diaphragm and the second diaphragm extend beyond the ends of the first electrode and the second electrode, and the maximum distance between the ends of the first diaphragm and the two ends of the first electrode and the second electrode is less than the distance B by which the first electrode is extended beyond the first diaphragm or the second diaphragm at the winding tail end.
11. A method for manufacturing a battery, characterized in that, The battery manufacturing method is used to manufacture a battery, the battery including a cell assembly, the cell assembly including a first electrode, a first separator, a second electrode, and a second separator sequentially stacked and wound relative to a winding center, the first electrode covering the second electrode at the winding tail end, and one of the first separator and the second separator covering the first electrode at the winding tail end, the battery manufacturing method including: Confirm the first preset distance D1 and / or the second preset distance D2; Cut off the winding tail end of the cell assembly so that the distance by which the first electrode extends beyond the second electrode is greater than or equal to the first preset distance D1; and / or so that the distance by which either the first diaphragm or the second diaphragm covers the first electrode extends beyond the first electrode is greater than or equal to the second preset distance D2.
12. The battery manufacturing method according to claim 11, characterized in that, The battery manufacturing method further includes: The first electrode and the second electrode are wound using a winding machine; The winding tail end of the second electrode sheet is first cut using a cutting machine; After the second electrode is wound at the winding tail end, the cutting position of the winding tail end of the first electrode is confirmed so that the dimension between the position of the outermost layer of the first electrode wound on the winding needle and the cutting position is greater than or equal to the first preset distance D1. The first electrode is cut at the cutting position.
13. The battery manufacturing method according to claim 11, characterized in that, The battery manufacturing method further includes: Collect defective products from the manufactured battery cell assemblies; Measure and count the length of the defective area at the winding tail end of the multiple defective products, and determine the first preset distance D1 or the second preset distance D2 based on the length of the defective area.