Cylindrical battery roll core structure and cylindrical battery

Abstract

The utility model discloses a kind of cylindrical battery roll core structure and cylindrical battery, cylindrical battery roll core structure includes positive plate, diaphragm and negative plate, the one side of the negative plate integrally is provided with extension section, the extension section is wound to form center tube, the positive plate, the diaphragm and the negative plate are wound in the outside of the center tube and form roll core;Advantage is helpful to improve production efficiency, and reduce production cost.

Description

Technical Field

[0001] This utility model belongs to the field of battery technology, and in particular relates to a cylindrical battery core structure and a cylindrical battery. Background Technology

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

[0003] During charge-discharge cycles, the core of a cylindrical battery undergoes volume changes (expansion and contraction), generating lateral compressive stress. Because the core is encased in a steel shell, this stress is transmitted from the outside in, potentially causing internal collapse. To address this issue, the conventional method is to insert a center pin at the center of the core to improve its internal lateral rigidity. While there are various designs for the center pin, as a separate component, it requires additional assembly, increasing the complexity of the cylindrical battery assembly process, reducing production efficiency, and raising production costs. Utility Model Content

[0004] The technical problem to be solved by this utility model is to provide a cylindrical battery core structure and a cylindrical battery, which helps to improve production efficiency and reduce production costs.

[0005] The technical solution adopted by this utility model to solve the above-mentioned technical problems is as follows: a cylindrical battery core structure, including a positive electrode sheet, a separator and a negative electrode sheet, wherein an extension section is integrally provided on one side of the negative electrode sheet, the extension section is wound to form a central tube, and the positive electrode sheet, the separator and the negative electrode sheet are wound around the outside of the central tube to form a core.

[0006] Preferably, the central tube has several drainage holes on its side, and the drainage holes penetrate the inner and outer sides of the central tube.

[0007] Preferably, the extension section is provided with multiple through holes, and when the extension section is wound to form the central tube, the through holes located on the same axis constitute the drainage holes.

[0008] Preferably, all the vias are arranged in an M×N matrix, with the vias in the first to Nth columns gradually approaching the negative electrode. The lateral spacing between the nth and (n-1)th columns is L, where L satisfies the following formula:

[0009]

[0010] Where 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 2≤n≤N with n being a positive integer.

[0011] Preferably, the extension section (4) 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, comprising a steel casing, wherein the cylindrical battery core structure described above is disposed within the steel casing.

[0014] Compared with the prior art, the advantages of this utility model are:

[0015] 1. By setting an extension section on one side of the negative electrode sheet, the extension section is pre-wound to form a central tube during processing, replacing the existing central pin and playing a supporting role. This counteracts the lateral compressive stress generated during the charging and discharging of the core. There is no need to separately assemble a central pin, which simplifies the processing method, helps to improve production efficiency, and reduces production costs.

[0016] 2. By setting through holes on the extension section, when the central tube is wound to form a central tube, the through holes located on the same axis will form a drainage hole, which can play the role of liquid injection and drainage. Attached Figure Description

[0017] Figure 1 This is a cross-sectional structural diagram of the cylindrical battery in this utility model.

[0018] Figure 2 This is a schematic diagram of the cylindrical battery core structure of this utility model when unfolded;

[0019] Figure 3 This is a schematic diagram of the structure of the negative electrode sheet and the extension section when unfolded in this utility model;

[0020] Figure 4 This is a schematic diagram of the structure of the extension section during winding in this utility model;

[0021] Figure 5 This is a schematic diagram of the cylindrical battery core structure during winding in this utility model;

[0022] Figure 6 This is a schematic diagram of charge-discharge cycle tests for Examples 1 and 3 and Comparative Examples 1 and 2.

[0023] In the diagram: 1. Positive electrode plate; 2. Separator; 3. Negative electrode plate; 4. Extension section; 41. Through hole; 5. Central tube; 51. Drain hole; 6. Core; 7. Steel shell. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0025] In the description of this utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model 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. Therefore, they should not be construed as limitations on this utility model.

[0026] Example 1: As Figures 1 to 4 As shown, a cylindrical battery includes a steel casing 7, within which a cylindrical battery core structure is disposed. The cylindrical battery core structure includes a positive electrode 1, a separator 2, and a negative electrode 3. An extension section 4 is integrally disposed on one side of the negative electrode 3. The extension section 4 is wound to form a central tube 5. The positive electrode 1, separator 2, and negative electrode 3 are wound around the outside of the central tube 5 to form a core 6. The extension section 4 has at least 3 turns, and both the negative electrode 3 and the extension section 4 are made of copper foil.

[0027] The fabrication method for this cylindrical battery core structure includes the following steps:

[0028] S1. Take the positive electrode, the separator, and the negative electrode with the extended section;

[0029] S2. Stack the positive electrode, separator and negative electrode, and make the extension section staggered from the positive electrode and separator;

[0030] S3. Wind the extension section onto the winding needle to form a central tube;

[0031] S4. The stacked positive electrode, separator and negative electrode are wound around the outside of the central tube to form a core;

[0032] S5. Pull out the winding needle, wrap the winding core with glue, and obtain the cylindrical battery winding core structure.

[0033] Example 2: The rest is the same as in Example 1, except that the central tube 5 has several drainage holes 51 on its side. The drainage holes 51 penetrate the inner and outer sides of the central tube 5 and serve to drain the liquid. Since the central tube 5 is formed by winding the extension section 4, multiple through holes 41 are provided on the extension section 4. When the extension section 4 is wound to form the central tube 5, the through holes 41 located on the same axis form the drainage holes 51.

[0034] The corresponding processing method for cylindrical battery core structures includes the following steps:

[0035] S1. Take the positive electrode, the separator, and the negative electrode with the extended section;

[0036] S2. Stack the positive electrode, separator and negative electrode, and make the extension section staggered from the positive electrode and separator;

[0037] S3. Drill holes in the extension section to obtain multiple through holes;

[0038] S4. The extension section is wound onto the winding needle to form a central tube, and the through holes on the same axis form a drainage hole;

[0039] S5. The stacked positive electrode, separator and negative electrode are wound around the outside of the central tube to form a core;

[0040] S6. Pull out the winding needle, wrap the winding core with glue, and obtain the cylindrical battery winding core structure.

[0041] Or it may include the following steps:

[0042] S1. Take the positive electrode, the separator, and the negative electrode with the extended section;

[0043] S2. Drill holes in the extension section to obtain multiple through holes;

[0044] S3. Stack the positive electrode, separator and negative electrode, and stagger the extension section from the positive electrode and separator;

[0045] S4. The extension section is wound onto the winding needle to form a central tube, and the through holes on the same axis form a drainage hole;

[0046] S5. The stacked positive electrode, separator and negative electrode are wound around the outside of the central tube to form a core;

[0047] S6. Pull out the winding needle, wrap the winding core with glue, and obtain the cylindrical battery winding core structure.

[0048] Example 3: The rest is the same as in 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 defined to gradually approach the negative electrode 3. The lateral spacing between the nth column and the (n-1)th column is L, and L satisfies the following formula:

[0049]

[0050] Where 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, and 2≤n≤N with n being a positive integer.

[0051] When the extension section 4 is wound to form the central tube 5, the odd-numbered through holes 41 in the same row form a 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.

[0052] Comparative Example 1: A cylindrical battery includes a steel shell, a core, and a center pin. The core is disposed inside the steel shell and is formed by winding a positive electrode sheet, a negative electrode sheet, and a separator. The core has a center hole, and the center pin engages with the center hole of the core. The side of the center pin has no drainage holes.

[0053] The existing assembly process for center pins involves first winding the positive electrode, negative electrode, and separator onto a winding needle to form a core with a central hole. Then, the winding needle is removed, the central hole is enlarged, and finally, the center pin is pressed into the central hole. This assembly process is not only complex but also results in a low yield. Furthermore, center pins are typically made of nickel, copper, or nickel-plated steel, requiring high-precision machining or stamping processes, leading to high manufacturing costs and difficulty in ensuring good consistency. This affects the reliability of the battery cell. Therefore, the use of center pins not only increases the overall weight of the battery cell and reduces its energy density but also introduces additional safety hazards.

[0054] Comparative Example 2: The rest of the parts are the same as Comparative Example 1, except that the side of the central needle has several drainage holes.

[0055] Examples 1, 3, Comparative Example 1, and Comparative Example 2 all used the same battery system, with individual cell capacities ranging from 6 ± 0.3 Ah. The positive electrode was NCM811, the negative electrode was lithium metal foil, and the separator and casing materials were identical. All batteries were tested at 25°C, with voltage tests ranging from 3.0V to 4.35V, a charging rate of 0.5C, and a discharging rate of 1C. Batteries were considered to have reached their service life when their discharge capacity retention rate fell below 80.0%. The results are shown in the table below. Figure 6 As shown.

[0056] Support components Does it have a hole? Cycle life Example 1 Central tube none 194 Example 3 Central tube Drainage hole 232 Comparative Example 1 center needle none 27 Comparative Example 2 center needle round hole 75

[0057] As shown in the table, the battery cell using the central tube disclosed in this patent as the support structure has a significantly better cycle life than the traditional central pin structure. This indicates that the central tube support structure is beneficial to improving the internal flow state of the battery cell and reducing uneven internal resistance distribution and local polarization.

[0058] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the implementation of the present invention is not limited to the above-described manner. Any improvements made by adopting the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A cylindrical battery jelly-roll structure comprising a positive electrode sheet (1), a separator (2), and a negative electrode sheet (3), characterized by: An extension section (4) is integrally provided on one side of the negative electrode (3). The extension section (4) is wound to form a central tube (5). The positive electrode (1), the diaphragm (2) and the negative electrode (3) are wound around the outside of the central tube (5) to form a core (6).

2. The cylindrical battery cell structure according to claim 1, wherein: The central tube (5) has several drainage holes (51) on its side, and the drainage holes (51) penetrate the inner and outer sides of the central tube (5).

3. The cylindrical battery cell structure according to claim 2, wherein: The extension section (4) is provided with a plurality of through holes (41). When the extension section (4) is wound to form the central tube (5), the through holes (41) located on the same axis form the drainage holes (51).

4. The cylindrical battery cell structure according to claim 3, wherein: All the vias (41) are arranged in an M×N matrix. The vias (41) in the first to the Nth columns are defined to gradually approach the negative electrode (3). The lateral spacing between the nth column and the (n-1)th column is L, which satisfies the following formula: Where 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), and n is a positive integer and 2≤n≤N.

5. The cylindrical battery cell structure according to claim 3, wherein: The extension section (4) is wound with no less than 3 turns.

6. The cylindrical battery cell structure according to claim 1, wherein: The negative electrode (3) and the extension section (4) are copper foil.

7. A cylindrical battery comprising a steel can (7), characterised in that: The steel shell (7) is provided with a cylindrical battery core structure as described in any one of claims 1 to 6.

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