Battery roll core, battery monomer and method for preventing collapse of central hole of battery

Abstract

The invention discloses a battery roll core, a battery monomer and a method for preventing collapse of a battery center hole, a diaphragm is subjected to empty rolling to form a primary winding part, an opening support ring sleeves the primary winding part, then the diaphragm is subjected to empty rolling to form a secondary winding part, the two winding parts and the opening support ring are used for supporting the center hole, and a center needle does not need to be inserted. A central pore channel can be kept unblocked, and electrolyte can be fully infiltrated; a continuous and stable support is provided in a battery cycle process, and the problem of cell collapse caused by expansion of a negative electrode material is effectively inhibited; the reserved space is obviously reduced, so that the energy density of the battery is improved; the defect that a large insertion hole needs to be reserved in a traditional center pin technology is overcome, pole piece damage possibly caused by the center pin insertion procedure is eliminated, and material loss in the production process is reduced. And while the supporting effect is ensured, the simplification of the production process and the improvement of the battery performance are realized.

Description

Technical Field

[0001] This invention belongs to the field of battery manufacturing, specifically relating to a battery core, a battery cell, and a method for preventing the collapse of the battery center hole. Background Technology

[0002] During the winding and charging / discharging processes of a battery, the stability of the center hole directly affects the cycle life and safety performance of the cell. The collapse of the center hole is essentially an instability phenomenon of a multi-layered composite material structure under complex stress. The forces involved mainly originate from variations in electrode thickness during charging and discharging, and uneven stress distribution at electrode insertion and termination points.

[0003] If the negative electrode material has a high volume expansion rate during lithium intercalation, it is prone to radial stress accumulation in the electrode sheet during long-term cycling, which can lead to instability and collapse of the core center hole structure.

[0004] When the central hole of the battery collapses, it manifests as wrinkles on the electrode facing the inner circle. The electrode at the wrinkled area is prone to light transmission and breakage. The broken electrode is very likely to cut the separator, allowing light to pass through and ultimately causing a short circuit inside the battery, resulting in a safety risk.

[0005] Currently, the common method to prevent the collapse of the center hole is the center pin technology. While the existing center pin technology can maintain the cavity structure during winding, it requires reserving excessive space to achieve production feasibility. Furthermore, the center pin is prone to scratching the electrode sheet during the extraction process, resulting in a high production yield loss. Summary of the Invention

[0006] This invention provides a battery core, a battery cell, and a method for preventing the collapse of the battery center hole. The method involves empty winding of a diaphragm to form a primary winding section, followed by empty winding of the diaphragm again to form a secondary winding section after an open support ring is fitted over the primary winding section. The two winding sections and the open support ring are used to support the center hole, eliminating the need to insert a center pin and overcoming the shortcomings described in the prior art.

[0007] The technical solution adopted in this invention is as follows: A battery core includes a positive electrode, a negative electrode, a first separator, a second separator, and an open support ring. The first and second separators are stacked and wound to form a primary winding section, which is located at the center of the battery core. The open support ring is fitted onto the primary winding section, and the first and second separators are wound again to form a secondary winding section. The open support ring is wrapped between the secondary winding section and the primary winding section. In the winding structure after the secondary winding section, the negative electrode is inserted between the first and second separators, and in the subsequent winding structure, the positive electrode is inserted between the first and second separators. The open support ring fitted onto the primary winding section forms uniform support, avoiding rigid friction damage between the traditional center pin and the electrode during the manufacturing process. Moreover, the diameter of the center hole formed by the primary winding section can be the same as the diameter of a conventional center hole, without affecting the loss of capacity and energy density. Furthermore, the open support ring has separators on both sides, which can ensure electrolyte wetting without affecting the winding tension.

[0008] As a preferred embodiment of the present invention, the number of turns of the primary winding portion is 2-10 turns.

[0009] As a preferred embodiment of the present invention, the central angle corresponding to the opening of the open support ring is 1°-180°; the thickness of the open support ring is 0.1~5mm; and the width is 2~60mm. The size of the opening is determined according to the equipment and the collapse control results. When it is fitted into the primary winding section, the opening is aligned with the winding position of the diaphragm. The open support ring has a certain degree of hardness, rigidity, resistance to high and low temperatures, and good chemical stability to resist the expansion force of the electrode sheet and withstand the baking temperature.

[0010] As a preferred embodiment of the present invention, the number of winding turns of the secondary winding section is 2-20.

[0011] The present invention also provides a battery cell, including a housing assembly and the aforementioned battery core, wherein the battery core is disposed within the housing assembly.

[0012] The present invention also provides a method for preventing the collapse of the center hole of a battery, the steps of which are as follows: After the first and second separators are stacked, they are first wound several times to form a primary winding section. The primary winding section is located at the center of the battery core and has a central hole. An open support ring is fitted onto the primary winding section; the open support ring is fitted onto the primary winding section with its opening facing the diaphragm in-winding position, and evenly supports the primary winding section. The first and second diaphragms are wound together again to form a secondary winding section. The secondary winding section wraps around the open support ring, so that the open support ring is wrapped between the primary winding section and the secondary winding section. The open support ring has diaphragms on both sides, which ensures that the electrolyte is wetted without affecting the winding tension. The negative electrode sheet is inserted between the first and second separators and wound up. The positive electrode is then inserted between the first and second diaphragms and wound until completion. An open support ring is wound synchronously with the electrode, providing central support and ensuring a balance between support strength and electrolyte permeation.

[0013] As a preferred embodiment of the present invention, the number of turns of the primary winding portion is 2-10 turns.

[0014] As a preferred embodiment of the present invention, the central angle corresponding to the opening of the open support ring is 1°-180°; the thickness of the open support ring is 0.1~5mm; and the width is 2~60mm.

[0015] The beneficial effects of this invention are as follows: 1. It can keep the central channel unobstructed, ensuring that the electrolyte can fully wet the surface; 2. Provides continuous and stable support during battery cycling, effectively suppressing cell collapse caused by the expansion of negative electrode materials; 3. Compared with traditional center pin technology, it can significantly reduce the reserved space, thereby improving battery energy density; 4. It overcomes the shortcomings of traditional center pin technology, which requires a large insertion gap. The large gap reserved in traditional designs due to production losses actually weakens the support effect. 5. It eliminates potential electrode damage caused by the center pin insertion process, reducing material waste during production.

[0016] 6. While ensuring the supporting effect, the production process was simplified and the battery performance was improved. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the assembly of the open support ring, the primary winding part, and the secondary winding part of the present invention.

[0019] Figure 2 This is a schematic diagram of the structure of the open support ring of the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Traditional center pin structure experiment: After the battery core is wound, a center pin is inserted into the center hole of the core. After the battery is wound, the empty separator at the center hole is prone to loosening due to the lack of internal support, making it difficult to insert the center pin and easily damaging the electrode assembly, resulting in a high production loss rate. To reduce production losses, the diameter of the center pin should be reduced. However, after reducing the diameter of the center pin to 50%-70% of the winding pin, there is no significant difference in the collapse of the center hole of the battery with and without a center pin.

[0022] Experiments on traditional center pin structures with different diameters: When the diameter of the center pin is reduced to 50%-70% of the coiled pin diameter, there is no significant difference in the collapse of the center hole between batteries with and without center pins. To further improve the abnormality of center hole collapse, center pins with diameters as close as possible to the coiled pin diameter were manually inserted into the center hole. The experimental results showed that when the diameter of the center pin is close to more than 80% of the coiled pin diameter, the number of collapse cycles of the center hole is significantly reduced, and the length of light transmission on the electrode is also significantly reduced. As the diameter of the center pin gradually approaches the coiled pin diameter, the number of collapse cycles of the center hole also gradually decreases, from 3-4 cycles in fresh batteries to 1-2 cycles, and the length of light transmission on the electrode also gradually decreases. After cycling, the light transmission phenomenon of the battery electrode gradually decreases from linear light transmission to point light transmission.

[0023] However, to insert into the center hole, a larger gap must be reserved to account for production losses, and reserving a larger gap actually weakens the support effect.

[0024] This invention provides an embodiment of a battery winding core, such as... Figure 1 As shown, it includes a first separator 1, a second separator 2, and an open support ring 3; the first separator 1 and the second separator 2 are stacked and wound 2-10 turns to form a primary winding part. The primary winding part is located at the center of the battery core, and the center of the primary winding part is a central hole. The diameter of the central hole can be the same as that of a conventional central hole, so as not to affect the loss of capacity and energy density.

[0025] An open support ring is fitted onto the primary winding section, such as... Figure 2As shown, the central angle corresponding to the opening of the open support ring is 1°-180°, the thickness is 0.1~5mm, and the width is 2~60mm. The size of the opening is determined according to the equipment and collapse control results. When it is fitted into the primary winding section, the opening is aligned with the in-winding position of the diaphragm. The open support ring has a certain degree of hardness, rigidity, resistance to high and low temperatures, and good chemical stability to resist the expansion force of the electrode sheet and withstand the baking temperature.

[0026] The first and second diaphragms are wound again for 2-20 turns to form a secondary winding section; the open support ring is wrapped between the secondary winding section and the primary winding section; both sides of the open support ring have diaphragms, which can ensure electrolyte wetting and not affect the winding tension.

[0027] In the winding structure after the secondary winding section, the negative electrode sheet is inserted between the first diaphragm and the second diaphragm, and in the subsequent winding structure, the positive electrode sheet is inserted between the first diaphragm and the second diaphragm.

[0028] The present invention also provides an embodiment of a battery cell, including a housing assembly and the aforementioned battery core, wherein the battery core is disposed within the housing assembly.

[0029] The present invention also provides an embodiment of a method for preventing the collapse of the central hole of a battery, the steps of which are as follows: After the first and second separators are stacked, they are first wound 2-10 times to form a primary winding section. The primary winding section is located at the center of the battery core and has a central hole; the diameter of the central hole is the same as that of a conventional central hole.

[0030] An open support ring is fitted onto the primary winding section; the open support ring is fitted onto the primary winding section with its opening facing the diaphragm in-winding position, and evenly supports the primary winding section. The first and second diaphragms are wound together again to form a secondary winding section. The secondary winding section wraps around the open support ring, so that the open support ring is wrapped between the primary winding section and the secondary winding section. The open support ring has diaphragms on both sides, which ensures that the electrolyte is wetted without affecting the winding tension. The negative electrode sheet is inserted between the first and second diaphragms and wound up. The positive electrode is then inserted between the first and second separators and wound until completion. An open support ring is wound synchronously with the electrode, providing central support and ensuring a balance between support strength and electrolyte penetration. The open support ring fits tightly to the electrode, preventing collapse due to uneven force during electrode insertion or electrode expansion, as there is no space for displacement. Compared to traditional center pin technology, this invention significantly reduces the required space, increases energy density, and avoids electrode damage caused by center pin insertion, thus reducing production losses.

[0031] In this specification, the terms "an embodiment," "example," "specific example," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. 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.

[0032] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A battery core, characterized in that: The battery includes a positive electrode, a negative electrode, a first separator, a second separator, and an open support ring. The first and second separators are stacked and wound into a primary winding section, which is located at the center of the battery core. The open support ring is fitted onto the primary winding section, and the first and second separators are wound again to form a secondary winding section. The open support ring is wrapped between the secondary winding section and the primary winding section. In the winding structure after the secondary winding section, the negative electrode is inserted between the first and second separators, and in the subsequent winding structure, the positive electrode is inserted between the first and second separators.

2. The battery core according to claim 1, characterized in that: The number of turns in the primary winding section is 2-10.

3. The battery core according to claim 1 or 2, characterized in that: The central angle corresponding to the opening of the open support ring is 1°-180°; the thickness of the open support ring is 0.1~5mm; and the width is 2~60mm.

4. The battery core according to claim 3, characterized in that: The number of turns in the secondary winding section is 2-20.

5. A single battery cell, characterized in that: It includes a housing assembly and a battery core as described in any one of claims 1-4, wherein the battery core is disposed within the housing assembly.

6. A method for preventing the collapse of the center hole of a battery, characterized in that, The steps are as follows: After the first and second separators are stacked, they are first wound several times to form a primary winding section. The primary winding section is located at the center of the battery core and has a central hole. The open support ring is fitted onto the primary winding section; The first and second diaphragms are wound together again to form a secondary winding section. The secondary winding section wraps around the open support ring, so that the open support ring is wrapped between the primary winding section and the secondary winding section. The negative electrode sheet is inserted between the first and second separators and wound up. Then the positive electrode sheet is inserted between the first and second separators and continued to be wound until the winding is finished.

7. The method for preventing the collapse of the battery center hole according to claim 6, characterized in that: The number of turns in the primary winding section is 2-10.

8. The method for preventing the collapse of the battery center hole according to claim 6, characterized in that: The central angle corresponding to the opening of the open support ring is 1°-180°; the thickness of the open support ring is 0.1~5mm; and the width is 2~60mm.

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