Processing method of roll core structure, cylindrical battery roll core structure and cylindrical battery

Abstract

The invention discloses a processing method of a roll core structure, a cylindrical battery roll core structure and a cylindrical battery. The processing method of the roll core structure comprises the following steps: S1, taking a positive plate, a diaphragm and a negative plate with an extension section; s2, stacking the positive plate, the diaphragm and the negative plate, and enabling the extension section to be staggered from the positive plate and the diaphragm; s3, winding the extension section on a winding needle to form a central tube; s4, winding the stacked positive plate, diaphragm and negative plate on the outer side of the central tube to form a winding core; s5, drawing out the winding needle, and encapsulating the winding core to obtain a cylindrical battery winding core structure; the method has the advantages that the processing procedure can be simplified, the production efficiency can be improved, and the production cost can be reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, and in particular relates to a processing method of a winding core structure, a cylindrical battery winding core structure, and a cylindrical battery. Background Art

[0002] Cylindrical batteries, with their advantages of compact size, high energy density, simple structure, and mature manufacturing, have become a mainstream technology solution in the power battery and energy storage fields. With the continuous development of battery technology, the widespread use of high-energy-density materials such as high-nickel cathodes and silicon-based anodes has significantly increased the energy density of cylindrical battery cells. However, while battery performance has been optimized, internal mechanical stress has become increasingly prominent.

[0003] During the charge and discharge cycle of a cylindrical battery, the core will undergo volume changes (expansion and contraction), generating lateral extrusion stress. Since a steel shell is provided on the outside of the core, the extrusion stress will be transmitted from the outside to the inside, which may cause the inside of the core to collapse. In order to solve this problem, the current conventional method is to insert a center needle at the center of the core to improve the lateral rigidity of the core. Although there are many designs for the center needle, the center needle, as an independent component, requires additional assembly, which increases the assembly process of the cylindrical battery, making the assembly process more complicated, reducing production efficiency and increasing production costs. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a processing method of a roll core structure, a cylindrical battery roll core structure and a cylindrical battery, which can simplify the processing steps, help improve production efficiency, and reduce production costs.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is: a processing method for a winding core structure, comprising the following steps: S1, taking a positive electrode sheet, a diaphragm and a negative electrode sheet with an extension section; S2, stacking the positive electrode sheet, the diaphragm and the negative electrode sheet, and staggering the extension section with the positive electrode sheet and the diaphragm; S3, winding the extension section onto a winding needle to form a central tube; S4, winding the stacked positive electrode sheet, the diaphragm and the negative electrode sheet on the outside of the central tube to form a winding core; S5, pulling out the winding needle, wrapping the winding core with glue, and obtaining a cylindrical battery winding core structure.

[0006] And a processing method for a winding core structure, comprising the following steps: S1, taking a positive electrode sheet, a separator and a negative electrode sheet with an extension section; S2, stacking the positive electrode sheet, the separator and the negative electrode sheet, and staggering the extension section with the positive electrode sheet and the separator; S3, punching holes in the extension section to obtain multiple through holes; S4, winding the extension section onto a winding needle to form a central tube, and the through holes located on the same axis constitute drainage holes; S5, winding the stacked positive electrode sheet, the separator and the negative electrode sheet onto the outside of the central tube to form a winding core; S6, pulling out the winding needle, wrapping the winding core with glue, and obtaining a cylindrical battery winding core structure.

[0007] And a processing method for a winding core structure, comprising the following steps: S1, taking a positive electrode sheet, a separator and a negative electrode sheet with an extension section; S2, punching holes in the extension section to obtain multiple through holes; S3, stacking the positive electrode sheet, the separator and the negative electrode sheet, and staggering the extension section with the positive electrode sheet and the separator; S4, winding the extension section onto a winding needle to form a central tube, and the through holes located on the same axis constitute drainage holes; S5, winding the stacked positive electrode sheet, the separator and the negative electrode sheet onto the outside of the central tube to form a winding core; S6, pulling out the winding needle, wrapping the winding core with glue, and obtaining a cylindrical battery winding core structure.

[0008] Preferably, all the through holes are arranged in an M×N matrix, and the through holes from the first column to the Nth column are gradually close to the negative electrode sheet, and the lateral spacing between the nth column and the (n-1th column is L, and L satisfies the following formula:

[0009]

[0010] Wherein, M is the number of rows, N is the number of columns, d is the inner diameter of the central tube, μ is the thickness of the extension section, and n is a positive integer and 2≤n≤N.

[0011] Preferably, the extension section is wound with no less than 3 turns.

[0012] Preferably, the negative electrode sheet and the extension section are copper foil.

[0013] And a cylindrical battery core structure, which is obtained by using the above-mentioned processing method of a core structure.

[0014] And a cylindrical battery, comprising a steel shell, wherein the cylindrical battery core structure is arranged inside the steel shell.

[0015] Compared with the prior art, the advantages of the present invention are:

[0016] 1. By providing an extension section on one side of the negative electrode sheet, the extension section is pre-rolled to form a center tube during processing, replacing the existing center pin, playing a supporting role and offsetting the lateral extrusion stress generated by the winding core during charging and discharging. The center pin does not need to be separately assembled, which can simplify the processing process, help improve production efficiency, and reduce production costs.

[0017] 2. By setting through holes on the extension section, when winding to form a central tube, the through holes located on the same axis will form drainage holes, which can play a role in liquid injection and drainage. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the cross-sectional structure of the cylindrical battery in the present invention.

[0019] Figure 2 Schematic diagram of the structure of the winding core structure of the present invention when it is unfolded;

[0020] Figure 3 Schematic diagram of the structure of the negative electrode sheet and the extension section when unfolded in the present invention;

[0021] Figure 4 This is a schematic structural diagram of the extension section during winding in the present invention;

[0022] Figure 5 This is a schematic diagram of the structure of the winding core structure of the present invention when it is wound;

[0023] Figure 6 Schematic diagram of charge-discharge cycle test of Examples 1 and 3 and Comparative Examples 1 and 2.

[0024] In the figure: 1. positive electrode sheet; 2. diaphragm; 3. negative electrode sheet; 4. extension section; 41. through hole; 5. center tube; 51. drainage hole; 6. winding core; 7. steel shell. DETAILED DESCRIPTION

[0025] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0026] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are 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 direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the present invention.

[0027] Example 1: As shown in the figure, a cylindrical battery comprises a steel shell 7, within which is disposed a cylindrical battery core 6 structure. The cylindrical battery core 6 structure comprises a positive electrode sheet 1, a separator 2, and a negative electrode sheet 3. An extension section 4 is integrally provided on one side of the negative electrode sheet 3. The extension section 4 is wound to form a central tube 5. The positive electrode sheet 1, separator 2, and negative electrode sheet 3 are wound around the outer side of the central tube 5 to form the core 6. The extension section 4 is wound at least three times, and both the negative electrode sheet 3 and the extension section 4 are made of copper foil.

[0028] The processing method of the cylindrical battery core structure includes the following steps:

[0029] S1. Take the positive electrode sheet, the separator and the negative electrode sheet with the extension section;

[0030] S2, stack the positive electrode sheet, separator and negative electrode sheet, and stagger the extension section with the positive electrode sheet and separator;

[0031] S3, winding the extension section onto the winding needle to form a central tube;

[0032] S4, winding the stacked positive electrode sheet, separator, and negative electrode sheet on the outside of the central tube to form a winding core;

[0033] S5. Pull out the winding needle and wrap the core with glue to obtain a cylindrical battery core structure.

[0034] Example 2: The remainder of the embodiment is identical to Example 1, except that a plurality of drainage holes 51 are provided on the side of the central tube 5. These holes 51 extend through both the inner and outer sides of the central tube 5 and serve to drain the liquid during injection. Since the central tube 5 is formed by winding the extension 4, the plurality of through holes 41 provided on the extension 4 ensure that, when the extension 4 is wound to form the central tube 5, the through holes 41 located on the same axis form the drainage holes 51.

[0035] The processing steps of the corresponding cylindrical battery core structure processing method include the following steps:

[0036] S1. Take the positive electrode sheet, the separator and the negative electrode sheet with the extension section;

[0037] S2, stack the positive electrode sheet, separator and negative electrode sheet, and stagger the extension section with the positive electrode sheet and separator;

[0038] S3, punching holes on the extension section to obtain multiple through holes;

[0039] S4, winding the extension section onto the winding needle to form a central tube, and the through holes located on the same axis form drainage holes;

[0040] S5, winding the stacked positive electrode sheet, separator, and negative electrode sheet on the outside of the central tube to form a winding core;

[0041] S6. Pull out the winding needle and wrap the core with glue to obtain a cylindrical battery core structure.

[0042] Or include the following steps:

[0043] S1. Take the positive electrode sheet, the separator and the negative electrode sheet with the extension section;

[0044] S2, punching holes on the extension section to obtain multiple through holes;

[0045] S3, stacking the positive electrode sheet, the separator and the negative electrode sheet, and staggering the extension section with the positive electrode sheet and the separator;

[0046] S4, winding the extension section onto the winding needle to form a central tube, and the through holes located on the same axis form drainage holes;

[0047] S5, winding the stacked positive electrode sheet, separator, and negative electrode sheet on the outside of the central tube to form a winding core;

[0048] S6. Pull out the winding needle and wrap the core with glue to obtain a cylindrical battery core structure.

[0049] Example 3: The rest of the structure is the same as Example 2, except that all through holes 41 are arranged in an M×N matrix. The through holes 41 in the first to Nth columns are gradually closer to the negative electrode sheet 3. The lateral spacing between the nth column and the (n-1th) column is L, and L satisfies the following formula:

[0050]

[0051] Wherein, M is the number of rows, N is the number of columns, d is the inner diameter of the central tube 5 , μ is the thickness of the extension section 4 , 2≤n≤N and n is a positive integer.

[0052] When the extension section 4 is wound to form the central tube 5 , the odd-numbered through holes 41 in the same row form one drainage hole 51 , and the even-numbered through holes 41 in the same row form another drainage hole 51 . At this time, the central tube 5 has two rows of drainage holes 51 .

[0053] Comparative Example 1: A cylindrical battery, including a steel shell, a winding core and a center needle. The winding core is arranged in the steel shell, and the winding core is formed by winding a positive electrode sheet, a negative electrode sheet and a separator. The winding core has a center hole, and the center needle is snap-fitted with the center hole of the winding core. There is no drainage hole on the side of the center needle.

[0054] When assembling an existing center pin, the positive electrode sheet, negative electrode sheet, and separator must first be wound onto the pin to form a core with a center hole. The pin is then removed, the center hole is expanded, and the center pin is pressed into the center hole. This assembly process is not only complex but also has a low yield rate. Furthermore, the center pin is typically made of nickel, copper, or nickel-plated steel, requiring high-precision turning or stamping processes. This processing is costly and difficult to ensure good consistency, which can affect the reliability of the battery cell. Therefore, the installation of the center pin not only increases the overall mass of the battery cell and reduces its energy density, but also creates additional safety risks.

[0055] Comparative Example 2: The rest of the components are the same as those of Comparative Example 1, except that a plurality of drainage holes are provided on the side of the central needle.

[0056] Example 1, Example 3, Comparative Example 1 and Comparative Example 2 use the same battery system, and the capacity of the single battery is within the range of 6±0.3Ah. The positive electrode of the battery is NCM811, the negative electrode is lithium metal foil negative electrode, the diaphragm, steel shell materials, etc. are consistent, all batteries are tested in an environment of 25°C, the voltage test range is 3.0V~4.35V, the charging rate is 0.5C, and the discharge rate is 1C. When the battery discharge capacity retention rate is lower than 80.0%, it is determined that the battery has reached the end of its service life. The results are shown in the following table and Figure 6 shown.

[0057] Support Is there a hole Cycle life Example 1 Center tube none 194 Example 3 Center tube drainage holes 232 Comparative Example 1 Center needle none 27 Comparative Example 2 Center needle round hole 75

[0058] As can be seen from the table, the cycle life of the battery cell using the central tube disclosed in this patent as the support structure is significantly better than that of the traditional central pin structure, indicating that the central tube support structure is beneficial to improving the internal flow state of the battery cell and reducing the uneven distribution of internal resistance and local polarization.

[0059] The present invention is described above by way of example in conjunction with the accompanying drawings. It is obvious that the implementation of the present invention is not limited to the above-mentioned method. As long as various improvements are made using the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the scope of protection of the present invention.

Claims

1. A method for processing a core structure, characterized in that: The following steps are involved: S1. Take the positive electrode sheet, the separator and the negative electrode sheet with the extension section; S2, stack the positive electrode sheet, separator and negative electrode sheet, and stagger the extension section with the positive electrode sheet and separator; S3, winding the extension section onto the winding needle to form a central tube; S4, winding the stacked positive electrode sheet, separator, and negative electrode sheet on the outside of the central tube to form a winding core; S5. Pull out the winding needle and wrap the core with glue to obtain a cylindrical battery core structure.

2. A method for processing a core structure, characterized in that: The following steps are involved: S1. Take the positive electrode sheet, the separator and the negative electrode sheet with the extension section; S2, stack the positive electrode sheet, separator and negative electrode sheet, and stagger the extension section with the positive electrode sheet and separator; S3, punching holes on the extension section to obtain multiple through holes; S4, winding the extension section onto the winding needle to form a central tube, and the through holes located on the same axis form drainage holes; S5, winding the stacked positive electrode sheet, separator, and negative electrode sheet on the outside of the central tube to form a winding core; S6. Pull out the winding needle and wrap the core with glue to obtain a cylindrical battery core structure.

3. A method for processing a core structure, characterized in that: The following steps are involved: S1. Take the positive electrode sheet, the separator and the negative electrode sheet with the extension section; S2, punching holes on the extension section to obtain multiple through holes; S3, stacking the positive electrode sheet, the separator and the negative electrode sheet, and staggering the extension section with the positive electrode sheet and the separator; S4, winding the extension section onto the winding needle to form a central tube, and the through holes located on the same axis form drainage holes; S5, winding the stacked positive electrode sheet, separator, and negative electrode sheet on the outside of the central tube to form a winding core; S6. Pull out the winding needle and wrap the core with glue to obtain a cylindrical battery core structure.

4. A method for processing a winding core structure according to claim 2 or 3, characterized in that: All the through holes are arranged in an M×N matrix, and the through holes from the first column to the Nth column are gradually close to the negative electrode sheet. The lateral spacing between the nth column and the (n-1th column) is L, and L satisfies the following formula: Wherein, M is the number of rows, N is the number of columns, d is the inner diameter of the central tube, μ is the thickness of the extension section, and n is a positive integer and 2≤n≤N.

5. A method for processing a winding core structure according to any one of claims 1 to 3, characterized in that: The number of turns of the extension section is not less than 3 turns.

6. A method for processing a winding core structure according to any one of claims 1 to 3, characterized in that: The negative electrode sheet and the extension section are copper foil.

7. A cylindrical battery core structure, characterized by: The core structure is obtained by processing the core structure according to any one of claims 1 to 3.

8. A cylindrical battery comprising a steel shell, characterized in that: The cylindrical battery core structure as claimed in claim 6 is arranged in the steel shell.

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