Diaphragm, battery roll core and battery
By introducing ceramic and adhesive layers into the separator, the problem of breakage caused by misalignment at the tail of the positive electrode sheet was solved, thereby improving battery safety and extending battery life while reducing safety hazards.
Patent Information
- Application Number
- CN202520175787.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-26
- Publication Date
- 2026-03-06
- Estimated Expiration
- 2035-01-26
AI Technical Summary
During the charging and discharging process, the positive electrode at the tail of a cylindrical soft-pack lithium-ion battery is prone to breakage due to misalignment, leading to safety hazards and shortened service life.
A separator is used, which includes a base membrane, a ceramic layer and a gel layer. The gel layer faces the positive electrode and can absorb electrolyte and swell, providing elastic buffer, releasing expansion stress and reducing the risk of electrode breakage.
It effectively reduces the risk of breakage in the misaligned area at the tail of the positive electrode, improves battery safety performance, extends service life, and saves costs.
Smart Images
Figure CN223978040U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of battery technology, and in particular to a separator, a battery core, and a battery. Background Technology
[0002] Cylindrical pouch lithium-ion batteries have shown promising prospects in recent years in applications such as e-cigarettes, smart headphones, styluses, and various smart home consumer products due to their high maturity, good consistency, high energy density, low cost, and high production efficiency.
[0003] The core structure of a cylindrical pouch lithium-ion battery consists of a positive electrode sheet, a separator, and a negative electrode sheet stacked and wound together in a specific order. During the winding process, the tail of the positive electrode sheet may shift to a certain extent relative to other or intended positions, forming a misaligned area. During the cyclic charging and discharging of the cylindrical pouch lithium-ion battery, the core structure expands and contracts to some extent. This can cause the misaligned area at the tail of the positive electrode sheet to be prone to breakage under the action of expansion stress (shear force), thus affecting battery performance, shortening lifespan, and increasing safety hazards.
[0004] Therefore, there is an urgent need to design a separator, battery core, and battery to solve the above technical problems. Utility Model Content
[0005] The primary objective of this invention is to provide a separator that can reduce the risk of breakage in the misaligned area at the tail of the positive electrode, thereby reducing battery safety hazards and extending service life.
[0006] To achieve this objective, the present invention adopts the following technical solution:
[0007] This utility model provides a diaphragm, comprising:
[0008] Base film; a ceramic layer and an adhesive layer are sequentially stacked on the base film;
[0009] Alternatively, an adhesive layer may be provided on the base film, and ceramic particles may be embedded in the adhesive layer;
[0010] The adhesive layer is disposed towards the side closest to the positive electrode sheet and is configured to adhere to the positive electrode sheet; the adhesive layer is capable of absorbing electrolyte and swelling, and the adhesive layer is elastic.
[0011] As an alternative technical solution for the diaphragm, the adhesive layer expands in volume by 70%-300% after absorbing the electrolyte.
[0012] As an alternative technical solution for the diaphragm, the base membrane is made of PP or PE.
[0013] As an alternative technical solution for the diaphragm, the ceramic layer is made of alumina, boehmite, or zirconium oxide.
[0014] As an alternative technical solution for the diaphragm, the adhesive layer is made of one of PVDF, PVDF-HFP, or PMMA.
[0015] As an optional technical solution for the diaphragm, the thickness of the base membrane is set to 5μm-20μm.
[0016] As an alternative technical solution for the diaphragm, the thickness of the adhesive layer is greater than the particle size of the ceramic particles.
[0017] As an optional technical solution for the diaphragm, the thickness of the ceramic layer is set to 1.0μm-5μm, and the thickness of the adhesive layer is set to 0.5μm-10μm.
[0018] The second objective of this invention is to provide a battery core in which the tail misalignment area of the positive electrode sheet is less prone to breakage, thereby extending battery life and reducing safety hazards.
[0019] To achieve this objective, the present invention adopts the following technical solution:
[0020] This utility model provides a battery core, which includes a positive electrode sheet, a negative electrode sheet, and a separator as described in any of the above optional technical solutions. The separator is located between the positive electrode sheet and the negative electrode sheet, and the adhesive layer on the separator is bonded to the positive electrode sheet. The side of the separator away from the adhesive layer is bonded to the negative electrode sheet.
[0021] The third objective of this invention is to provide a battery that has high safety performance, can extend service life, and save costs.
[0022] To achieve this objective, the present invention adopts the following technical solution:
[0023] This utility model provides a battery, which includes a housing, a cap assembly, and the battery core described above. The battery core is disposed inside the housing, and the housing has an opening, which is sealed by the cap assembly.
[0024] The beneficial effects of this utility model include at least the following:
[0025] This invention provides a separator comprising a base film, a ceramic layer, and a binder layer. The ceramic layer and the binder layer are sequentially stacked on the base film; alternatively, the binder layer is disposed on the base film, and ceramic particles are embedded within the binder layer. The binder layer is positioned towards the side closest to the positive electrode and is configured to adhere to the positive electrode; the binder layer is capable of absorbing electrolyte and swelling, and is elastic.
[0026] In the above description, the adhesive layer is bonded to the positive electrode sheet. When electrolyte is injected into the battery, the adhesive layer absorbs the electrolyte and swells, causing its volume to expand and its thickness to increase. This increases the distance between the positive electrode sheet and the base film, providing space for stress release in the misaligned area at the tail of the positive electrode sheet during charge-discharge cycles. This allows the expansion stress (shear force) to be released, reducing the stress on the tail of the positive electrode sheet, lowering the risk of breakage, reducing safety hazards, and extending service life. Simultaneously, the adhesive layer retains some elasticity after absorbing electrolyte and swelling, providing a buffering effect on the tail of the positive electrode sheet to release expansion stress and prevent stress concentration that could lead to breakage.
[0027] This utility model also provides a battery core, in which the tail misalignment area of the positive electrode sheet is less prone to breakage, thus extending battery life and reducing safety hazards.
[0028] This utility model also provides a battery that has high safety performance, can extend service life, and save costs. Attached Figure Description
[0029] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments of this utility model will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the content of the embodiments of this utility model and these drawings without creative effort.
[0030] Figure 1 This is a schematic diagram of the diaphragm provided in Embodiment 1 of this utility model;
[0031] Figure 2 This is a schematic diagram of the structure of the battery core provided in Embodiment 1 of this utility model.
[0032] Figure Labels
[0033] 100, Base membrane; 200, Ceramic layer; 300, Adhesive layer; 400, Positive electrode sheet; 500, Negative electrode sheet; 600, Separator. Detailed Implementation
[0034] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0035] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.
[0036] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.
[0037] In the description of this utility model, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this utility model is in use. They are used only for the convenience of describing this utility model and for 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. Furthermore, the terms "first," "second," and "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.
[0038] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set" and "connection" 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 or an electrical connection. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.
[0039] In this invention, unless otherwise explicitly 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 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 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.
[0040] The embodiments of this utility model 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 utility model, and should not be construed as limiting this utility model.
[0041] Example 1
[0042] During lithium battery manufacturing, if misalignment occurs during the winding of the positive electrode sheet, especially in the misaligned area at the tail end, this misaligned area is susceptible to additional stress and torsion during subsequent charge-discharge cycles. Long-term stress and torsion can lead to fatigue and breakage of the positive electrode sheet.
[0043] Therefore, this embodiment provides a separator that can reduce the risk of breakage in the misaligned area at the tail of the positive electrode, reduce battery safety hazards, and extend service life.
[0044] like Figure 1 As shown, the separator mainly comprises a base membrane 100, a ceramic layer 200, and a binder layer 300. The ceramic layer 200 and the binder layer 300 are sequentially stacked on the base membrane 100. The binder layer 300 is positioned towards the side closest to the positive electrode and is configured to adhere to the positive electrode; the binder layer 300 can absorb electrolyte and swell, and it is elastic.
[0045] Based on the above design, in this embodiment, the adhesive layer 300 is bonded to the positive electrode sheet. When the battery is injected with electrolyte, the adhesive layer 300 absorbs the electrolyte and swells, causing the volume of the adhesive layer 300 to expand, i.e., increasing its thickness. This increases the distance between the positive electrode sheet and the base film 100, providing space for stress release in the misaligned area at the tail of the positive electrode sheet during battery charge-discharge cycles. This allows the expansion stress (shear force) to be released, reducing the stress on the tail of the positive electrode sheet, lowering the risk of breakage, reducing safety hazards, and extending service life. Simultaneously, the adhesive layer 300, after absorbing electrolyte and swelling, possesses a certain elasticity, which allows it to buffer the tail of the positive electrode sheet, releasing expansion stress and preventing stress concentration at the tail of the positive electrode sheet that could lead to breakage.
[0046] In addition, when the adhesive layer 300 absorbs the electrolyte and swells, the volume of the separator increases. During the swelling process of the adhesive layer 300, the adhesion between the separator and the positive and negative electrodes is increased, thereby improving the adhesion between the separator and the positive and negative electrodes and thus improving the performance of the battery.
[0047] Furthermore, after the adhesive layer 300 absorbs the electrolyte and swells, it can increase the electrolyte retention of the separator, thereby reducing or avoiding lithium plating during rapid charging or high-rate discharging of the battery due to the high current density of the negative electrode and the rapid consumption of electrolyte, thus improving the safety performance of the lithium-ion battery and extending its service life.
[0048] Optionally, in this embodiment, the adhesive layer 300 expands in volume by 70%-300% after absorbing the electrolyte. When the volume expansion is less than 70%, the change in distance between the adhesive layer 300 and the base film 100 is too small, which limits its effectiveness in improving battery expansion stress. When the volume expansion is greater than 300%, the separator undergoes excessive expansion deformation, which can easily cause battery bulging and other defects. Therefore, setting the volume expansion of the adhesive layer 300 after absorbing the electrolyte to 70%-300% can improve the expansion stress in the misaligned area at the tail of the positive electrode sheet, improve the product yield of the battery, and reduce safety hazards.
[0049] Optionally, the base film 100 in this embodiment can be made of PP (Polypropylene) or PE (Polyethylene).
[0050] Optionally, the ceramic layer 200 can be made of alumina, boehmite, or zirconium oxide, which improves the high-temperature resistance and heat shrinkage resistance of the separator, effectively preventing the separator from shrinking or melting under high-temperature conditions, thereby avoiding the risk of internal short circuits in the battery. The ceramic layer 200 has high hardness and strength, effectively enhancing the puncture resistance of the separator. This helps prevent battery damage under external impact or internal pressure, further reducing the risk of battery short circuits and combustion. Simultaneously, the ceramic layer 200 stabilizes the electrolyte in the battery, preventing decomposition or leakage under high temperature or mechanical pressure, helping to maintain the battery's ion conductivity and charge / discharge performance, thus extending battery life.
[0051] Optionally, the adhesive layer 300 in this embodiment can be made of one of PVDF (Polyvinylidene Fluoride), PVDF-HFP (Polyvinylidene Fluoride-Hexafluoropropylene), or PMMA (Polymethyl Methacrylate). These materials are low in cost, readily available, and ensure a strong and stable bond between the separator and the positive electrode.
[0052] Of course, in other embodiments, the base film 100, ceramic layer 200 and adhesive layer 300 can also be made of other materials, which will not be described in detail here.
[0053] Optionally, the thickness of the base film 100 in this embodiment can be set to 5μm-20μm.
[0054] When the thickness of the base film 100 is less than 5 μm, the separator's isolation effect will be significantly reduced, making contact between the positive and negative electrodes easier and increasing the risk of internal short circuits in the battery. Simultaneously, an excessively thin base film 100 may result in insufficient mechanical strength, making it prone to breakage. During battery assembly or use, even slight vibrations or impacts can cause the separator to rupture, leading to internal short circuits or electrolyte leakage.
[0055] When the thickness of the base film 100 exceeds 20 μm, the ion migration path inside the battery becomes longer, thus increasing the battery's internal resistance. Increased internal resistance reduces the battery's charge / discharge efficiency, requiring more energy to be consumed during charging and discharging. Simultaneously, increased base film 100 thickness occupies more battery space, thereby reducing the battery's energy density. This means that, for the same volume or weight, the amount of electricity the battery can store will be reduced.
[0056] Therefore, setting the thickness of the base film 100 between 5μm and 20μm not only provides good isolation, preventing the risk of short circuits inside the battery and improving the mechanical strength of the battery, but also reduces internal resistance and increases the energy density of the battery.
[0057] Optionally, the thickness of the ceramic layer 200 in this embodiment is set to 1.0 μm-5 μm. When the ceramic layer 200 is too thick (greater than 5 μm), it will increase the resistance to ion migration, leading to an increase in the internal resistance of the battery, which in turn will affect the charging and discharging efficiency and power output of the battery. When the ceramic layer 200 is too thin (less than 1.0 μm), its isolation effect may be insufficient, increasing the risk of internal short circuits in the battery; an excessively thin ceramic layer 200 may not be able to effectively resist thermal shrinkage or deformation under high-temperature conditions, thereby affecting the safety performance of the battery.
[0058] Optionally, the thickness of the adhesive layer 300 in this embodiment is set to 0.5μm-10μm. When the adhesive layer 300 is too thick (greater than 10μm), it increases the resistance to ion migration, leading to an increase in the internal resistance of the battery. Simultaneously, an excessively thick adhesive layer 300 may subject the battery core to greater stress during bending or folding, thus affecting the battery's flexibility and durability. Furthermore, an excessively thick adhesive layer 300 also increases the material consumption of the adhesive layer 300, increasing costs. When the adhesive layer 300 is too thin (less than 0.5μm), its adhesive strength may be insufficient, making it prone to separation of the separator from the positive electrode sheet during charging and discharging due to internal stress or vibration. Additionally, an excessively thin adhesive layer 300 exhibits less volume expansion after absorbing electrolyte, making it difficult to release the expansion stress at the tail of the positive electrode sheet. Therefore, in this embodiment, the adhesive layer 300 is set to 0.5μm-10μm, which can not only reduce the internal resistance of the battery, improve the flexibility and durability of battery assembly, and save consumables, but also improve the stability of the bonding between the separator and the positive electrode sheet, improve the expansion stress at the tail of the positive electrode sheet, and reduce the defective phenomenon of the positive electrode sheet breaking at the tail of the positive electrode sheet.
[0059] like Figure 2 As shown, this embodiment also provides a battery core, which includes a positive electrode 400, a negative electrode 500, and a separator 600. The separator 600 is located between the positive electrode 400 and the negative electrode 500, and the adhesive layer 300 on the separator 600 is bonded to the positive electrode 400. The side of the separator 600 facing away from the adhesive layer 300 is bonded to the negative electrode 500. The negative electrode 500, the separator 600, and the positive electrode 400 are stacked sequentially, and then wound by a winding device to finally form a battery core.
[0060] Understandably, the positive electrode 400 is... Figure 2 The negative electrode 500 is represented by a double-dotted line. Figure 2 The diaphragm 600 is indicated by a single-dot dash. Figure 2The solid line represents the area. Furthermore, the misalignment area at the tail of the positive electrode 400 is... Figure 2 The region A is represented by a wavy line.
[0061] Because the battery core has the structure of the separator 600, the tail misalignment area of the positive electrode 400 of the battery core is less prone to breakage, thus extending the battery life and reducing safety hazards.
[0062] This embodiment also provides a battery, which includes a housing, a cap assembly, and the aforementioned battery core. The battery core is disposed inside the housing, and the housing has an opening, which is sealed by the cap assembly.
[0063] This battery has high safety performance, can extend its service life, and save costs.
[0064] Example 2
[0065] This embodiment provides a separator that differs from that of Embodiment 1 in that: in this embodiment, an adhesive layer is disposed on the base membrane, and ceramic particles are embedded within the adhesive layer. In other words, the separator in this embodiment has a two-layer structure design, one layer being the base membrane, on which a mixture of the adhesive layer and ceramic particles is bonded. This reduces the thickness of the separator, lowers the internal resistance of the battery, and improves the charging and discharging efficiency of the battery; at the same time, it saves internal battery space, allowing more electrolyte to be placed within the limited internal space of the battery, thereby increasing the battery energy density.
[0066] Optionally, this embodiment does not limit the mixing ratio of the adhesive layer and ceramic particles in the mixture, and operators can flexibly adjust it according to actual needs.
[0067] Optionally, in this embodiment, the thickness of the adhesive layer is greater than the particle size of the ceramic particles, so that the ceramic particles can be completely embedded in the adhesive layer, ensuring the stable bonding performance between the adhesive layer and the positive electrode sheet.
[0068] In this embodiment, the remaining structure of the diaphragm is the same as in Embodiment 1, so it will not be described in detail here.
[0069] Obviously, the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments. Many other equivalent embodiments may be included without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
[0070] Note that in the description of this specification, the references to terms such as "some embodiments," "other embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this utility model. 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.
Claims
1. A diaphragm, characterized in that Comprise: a base film (100); a ceramic layer (200) and a glue layer (300) are sequentially stacked on the base film (100); Or, a glue layer (300) is arranged on the base film (100), and ceramic particles are embedded in the glue layer (300); The glue layer (300) is arranged towards the side close to the positive sheet, and the glue layer (300) is configured to be bonded with the positive sheet; the glue layer (300) can absorb electrolyte and swell, and the glue layer (300) has elasticity.
2. The separator according to claim 1, characterized in that The volume of the glue layer (300) expands by 70%-300% after absorbing electrolyte.
3. The separator of claim 1, wherein The material of the base film (100) is PP or PE.
4. The separator of claim 1, wherein The material of the ceramic layer (200) is one of alumina, boehmite or zirconium oxide.
5. The separator of claim 1, wherein The material of the glue layer (300) is one of PVDF, PVDF-HFP or PMMA.
6. The separator of claim 1, wherein The thickness of the base film (100) is set to 5-20 microns.
7. The diaphragm of claim 6, wherein The thickness of the glue layer (300) is greater than the particle size of the ceramic particles.
8. The septum of claim 6, wherein, The thickness of the ceramic layer (200) is set to 1.0-5 microns, and the thickness of the glue layer (300) is set to 0.5-10 microns.
9. A battery jelly-roll, characterized by The battery roll core comprises a positive sheet, a negative sheet and the separator of any one of claims 1-8, the separator is located between the positive sheet and the negative sheet, the glue layer (300) on the separator is bonded with the positive sheet, and the side of the separator away from the glue layer (300) is bonded with the negative sheet.
10. A battery characterized by The battery comprises a shell, a cap assembly and the battery roll core of claim 9, the battery roll core is arranged in the shell, the shell has an opening, and the cap assembly is sealed to the opening.