Battery cell, lithium ion battery and electric equipment

Abstract

The utility model discloses a battery cell, a lithium ion battery and electric equipment, the battery cell comprises a pole piece and a diaphragm, the diaphragm and the pole piece are laminated and wound, and the pole piece comprises a winding starting end and a winding ending end; the winding starting end and the winding ending end are respectively provided with an isolation belt for isolating the diaphragm from the pole piece. According to the technical scheme provided by the utility model, the isolation belts are arranged at the winding starting end and the winding ending end for isolating the diaphragm from the pole piece, so that the problem that burrs on the edge of the pole piece pierce the diaphragm is effectively solved; an effective physical isolation layer is formed between the winding starting end and the winding ending end, possibly generating burrs, of the pole piece and the diaphragm, direct contact between the burrs and the diaphragm is blocked, and the risk that the burrs of the pole piece pierce the adjacent diaphragm under the action of thermal stress is avoided, so that the risk of short circuit in a battery cell is reduced, the safety performance of the battery cell is improved, and the service life of the battery cell is prolonged.

Description

Technical Field

[0001] This utility model relates to the field of lithium-ion battery technology, and in particular to a battery cell, a lithium-ion battery, and an electrical device. Background Technology

[0002] With the widespread adoption of electric vehicles and portable electronic devices, lithium-ion batteries have become the mainstream electrochemical energy storage device due to their advantages such as high energy density, long cycle life, and low self-discharge rate. The safety and reliability of lithium-ion batteries are crucial for their large-scale application, especially in high-power and high-energy-density applications where battery safety performance cannot be ignored.

[0003] Currently, mainstream lithium-ion batteries adopt a wound-core structure design, which typically consists of a positive electrode, a negative electrode, a separator, and an electrolyte. In the traditional wound-core structure, the positive and negative electrode sheets are processed into the required shape and size through processes such as laser cutting, die cutting, or mechanical cutting, and then wound together with the separator to form the battery cell.

[0004] However, burrs often appear on the end faces or planes after the electrodes are cut, and these burrs are often difficult to completely avoid. During use, the battery cell generates heat due to charging and discharging. When the temperature rises, the electrodes will deform and expand, causing the existing burrs to pierce the adjacent separator under thermal stress. Once the separator is pierced, it will not only cause a local short circuit, but may also trigger thermal runaway, leading to separator melting holes. Utility Model Content

[0005] The main purpose of this invention is to propose a battery cell that aims to solve the problem of electrode burrs piercing the diaphragm under thermal stress, leading to diaphragm melting holes.

[0006] To achieve the above objectives, this utility model proposes a battery cell, comprising an electrode and a separator, wherein the separator and the electrode are stacked and wound together, and the electrode includes a winding start end and a winding end; both the winding start end and the winding end are provided with an isolation strip for isolating the separator and the electrode.

[0007] In some embodiments, the insulating strip includes a first insulating strip and a second insulating strip, wherein the first insulating strip is disposed between the starting end of the winding of the diaphragm and the electrode sheet, and the second insulating strip is disposed between the ending end of the winding of the diaphragm and the electrode sheet.

[0008] In some embodiments, the first isolation strip and the second isolation strip respectively cover the first and second ends of the diaphragm.

[0009] In some embodiments, the insulating strip includes a first insulating strip and a second insulating strip, wherein the first insulating strip covers the starting end of the winding of the electrode sheet; and the second insulating strip covers the ending end of the winding of the electrode sheet.

[0010] In some embodiments, the length of the isolation strip is 8 to 16 mm; the thickness of the isolation strip is 10 to 20 μm.

[0011] In some embodiments, the insulating strip is an insulating adhesive layer.

[0012] In some embodiments, the first insulating strip extends 2-5 mm beyond the starting end of the winding of the electrode sheet, and the second insulating strip extends 2-5 mm beyond the ending end of the winding of the electrode sheet.

[0013] In some embodiments, the electrode includes a positive electrode and a negative electrode, and the separator is disposed between the positive electrode and the negative electrode to separate the positive electrode and the negative electrode;

[0014] The first insulating strip includes a first sub-insulating strip and a second sub-insulating strip. The first sub-insulating strip covers the starting end of the winding of the positive electrode sheet, and the second sub-insulating strip is disposed between the separator and the starting end of the winding of the negative electrode sheet.

[0015] The second insulating strip includes a third sub-insulating strip and a fourth sub-insulating strip. The third sub-insulating strip covers the winding end of the positive electrode sheet, and the fourth sub-insulating strip is disposed between the separator and the winding end of the negative electrode sheet.

[0016] This utility model further proposes a lithium-ion battery, including a casing and a battery cell as described in the foregoing embodiment, wherein the casing forms a mounting cavity and the battery cell is disposed within the mounting cavity.

[0017] The present invention further proposes an electrical device, including the lithium-ion battery of the aforementioned embodiment.

[0018] The beneficial effects of this utility model are as follows: by setting an isolation strip at the starting end and the ending end of winding to isolate the separator and the electrode, the problem of burrs on the edge of the electrode piercing the separator is effectively solved. Specifically, by setting the isolation strip, an effective physical isolation layer is formed between the starting end and the ending end of winding where burrs may be generated on the electrode and the separator, blocking the direct contact between the burrs and the separator, avoiding the risk of the burrs on the electrode piercing the adjacent separator under thermal stress, thereby reducing the risk of internal short circuit in the cell and improving the safety performance and service life of the cell. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the battery cell structure in one embodiment of the present invention;

[0020] Figure 2 This is a schematic diagram of the battery cell structure in another embodiment of the present invention;

[0021] Figure 3 This is a schematic diagram of the battery cell structure in one embodiment of the present invention;

[0022] Figure 4 This is a schematic diagram of the battery cell structure in another embodiment of the present invention;

[0023] Figure 5 This is a schematic diagram of the battery cell structure in another embodiment of the present invention.

[0024] Explanation of icon numbers:

[0025] 100, Electrode; 100a, Winding start end; 100b, Winding end;

[0026] 110. Positive electrode plate; 110a. Starting end of winding the positive electrode plate; 110b. Ending end of winding the positive electrode plate; 120. Negative electrode plate; 120a. Starting end of winding the negative electrode plate; 120b. Ending end of winding the negative electrode plate;

[0027] 200. Diaphragm;

[0028] 300. Isolation strip;

[0029] 310. First isolation zone; 311. First sub-isolation zone; 312. Second sub-isolation zone;

[0030] 320. Second isolation zone; 323. Third sub-isolation zone; 324. Fourth sub-isolation zone.

[0031] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0032] The solutions in 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 a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this utility model.

[0033] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0034] It should also be noted that when a component is described as "fixed to" or "set on" another component, it can be directly on the other component or there may be an intervening component present. When a component is described as "connected to" another component, it can be directly connected to the other component or there may be an intervening component present.

[0035] Furthermore, the use of terms such as "first" and "second" in this utility model is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this utility model.

[0036] The electrode sheets are cut to a predetermined length, then stacked with the separator 200 and wound to form a core. This core is then placed into a housing, the tabs are treated accordingly, and electrolyte is injected into the housing for sealing, forming a single battery cell. During cycling, the battery heats up and expands. This expansion can cause burrs at the electrode cutting locations to puncture adjacent separators 200, potentially leading to thermal runaway, partial circuit breakage, or separator 200 perforation, posing safety hazards. Therefore, this invention proposes a battery cell with an insulating strip at the electrode cutting locations to physically separate burrs from the separator 200, thereby improving the cell's safety performance and lifespan. See details... Figure 1 An embodiment of this utility model proposes a battery cell, including an electrode 100 and a separator 200. The separator 200 and the electrode 100 are stacked and wound together. The electrode 100 includes a winding start end 100a and a winding end end 100b. Both the winding start end 100a and the winding end end 100b are provided with a separating strip for isolating the separator 200 and the electrode 100.

[0037] In this embodiment, the electrode 100 serves to carry the electrochemical reaction and conduct current, and is mainly composed of a current collector and an active material layer. The materials that can be used depend on different properties. For example, the positive electrode 110 can use aluminum foil as the current collector and be coated with positive active materials such as lithium nickel cobalt manganese oxide or lithium iron phosphate; the negative electrode 120 can use copper foil as the current collector and be coated with negative active materials such as graphite or silicon carbide.

[0038] In this embodiment, the diaphragm 200 serves to isolate the positive and negative electrodes, prevent short circuits, and allow lithium ions to pass through. It can be made of polymer materials such as polyethylene (PE), polypropylene (PP), or PE / PP composite film, and its thickness is usually 10-25 micrometers.

[0039] In this embodiment, the main function of the insulating tape 300 is to separate the burrs at the starting end 100a and the ending end 100b of the electrode 100 from the diaphragm 200. Its material can be insulating materials such as hot melt adhesive, polyimide tape, or fluoroplastic tape. The shape of the insulating tape 300 in this embodiment is not particularly limited; its main purpose is to cover the burrs and isolate the area. That is, its shape can be adjusted according to actual conditions and can be strip-shaped, sheet-shaped, or other suitable shapes. The width can be determined according to the distribution range of the burrs.

[0040] It should be noted that in this embodiment, an isolation strip 300 is provided between the starting end 100a of the winding of the electrode 100, the ending end 100b of the winding of the electrode 100 and the diaphragm 200. The isolation strip 300 may be attached to the diaphragm 200 or attached to the electrode 100. No particular limitation is made here.

[0041] Due to manufacturing requirements, the electrode 100 is cut to a predetermined length, resulting in microscopic burrs and irregular structures at its edges. During battery charge-discharge cycles, the electrode 100 undergoes thermal expansion due to temperature increases and absorbs electrolyte, causing volume changes. These factors can further accentuate the existing burrs and potentially puncture adjacent separators 200. By providing an insulating strip 300 between the starting end 100a and the ending end 100b of the electrode 100 and the separator 200, a physical insulating layer is formed, preventing direct contact between the burrs and the separator 200 and avoiding the risk of the burrs of the electrode 100 puncturing adjacent separators 200 under thermal stress.

[0042] Specifically, when the battery cell undergoes thermal expansion during cycling, the burrs will first come into contact with the insulating strip 300. Due to the flexibility and thickness of the insulating strip 300, the burrs will embed themselves into it under pressure and be blocked. Their sharp tips are absorbed and passivated by the insulating strip 300, preventing them from penetrating further into the separator 200. Simultaneously, the insulating properties of the insulating strip 300 ensure that even if the burrs are in complete contact with the insulating strip 300, no electrical short circuit will be formed. This design fully utilizes the principle of physical barrier, effectively improving the mechanical safety of the battery cell while maintaining its normal electrochemical performance.

[0043] The beneficial effects of this utility model are as follows: by setting an isolation strip 300 at the starting end 100a and the ending end 100b of the winding to isolate the separator 200 from the electrode 100, the problem of burrs on the edge of the electrode 100 piercing the separator 200 is effectively solved. Specifically, by setting the isolation strip 300, an effective physical isolation layer is formed between the starting end 100a and the ending end of the winding where burrs may be generated on the electrode 100 and the separator 200, blocking the direct contact between the burrs and the separator 200, avoiding the risk of the burrs of the electrode 100 piercing the adjacent separator 200 under thermal stress, thereby reducing the risk of internal short circuit in the battery cell and improving the safety performance and service life of the battery cell.

[0044] Furthermore, the technical solution of this utility model has a simple structure and is easy to implement. It only requires adding an insulating strip 300 at a specific position on the electrode 100, without changing the basic structure and manufacturing process of the battery cell. The increase in cost is limited, but the safety performance is significantly improved. At the same time, this design is applicable to various types of lithium-ion batteries, including but not limited to cylindrical, prismatic, and pouch batteries, and has broad applicability and promotional value. Through the implementation of this utility model, the risk of safety accidents caused by internal short circuits in batteries can be significantly reduced.

[0045] See Figure 1 , Figure 2 and Figure 3 In this embodiment, the isolation strip 300 includes a first isolation strip 310 and a second isolation strip 320. The first isolation strip 310 is disposed between the starting end 100a of the diaphragm 200 and the winding end 100b of the electrode 100.

[0046] In this embodiment, the cell isolation structure proposed by this invention employs two independent isolation strips 300 to protect different parts of the electrode 100. Specifically, the isolation strips 300 are divided into a first isolation strip 310 and a second isolation strip 320. The first isolation strip 310 is specifically positioned between the separator 200 and the winding start end 100a of the electrode 100 to protect the electrode 100 from burrs that may be generated at the initial winding position. The second isolation strip 320 is specifically positioned between the separator 200 and the winding end end 100b of the electrode 100 to protect the electrode 100 from burrs that may be generated at the winding end position. This partitioned arrangement can specifically address potential safety hazards that may occur at different positions of the electrode 100.

[0047] It should be noted that this embodiment only uses one electrode 100 as an example. Of course, in other embodiments, there can be multiple electrodes 100, such as a positive electrode 110 and a negative electrode 120. In this case, the number of first isolation strips 310 and second isolation strips 320 can be multiple. Accordingly, the first isolation strip 310 and the second isolation strip 320 can be respectively provided at the winding start end 100a and winding end end 100b of each electrode 100. For example, in a battery cell containing a positive electrode 110 and a negative electrode 120, the first isolation strip 310 can be provided at the winding start end 110a of the positive electrode and the second isolation strip 320 can be provided at the winding end end 110b of the positive electrode; similarly, the first isolation strip 310 can be provided at the winding start end 120a of the negative electrode and the second isolation strip 320 can be provided at the winding end end 120b of the negative electrode, thereby forming a complete protection system.

[0048] The first insulating strip 310 and the second insulating strip 320 can be made of the same or different materials, selected according to the differences in characteristics between the starting and ending ends of the electrode 100. For example, considering that the starting end 100a is usually located inside the cell and bears greater pressure, the first insulating strip 310 can be made of a material with higher strength and better elasticity; while the ending end 100b is usually located on the outer layer of the cell, the second insulating strip 320 can be made of a material with better insulation and stability. This differentiated design can further improve the isolation effect and provide more effective protection for the special needs of different locations.

[0049] Through the synergistic effect of the first isolation strip 310 and the second isolation strip 320, the cell structure provided in this embodiment can form a complete safety protection system throughout the entire process of winding the electrode 100, effectively avoiding the risk of internal short circuit in the cell caused by the burrs of the electrode 100 piercing the separator 200, and significantly improving the safety performance and service life of the cell.

[0050] In some embodiments, the first isolation strip 310 and the second isolation strip 320 are respectively wrapped around the first and last ends of the diaphragm 200. In this embodiment, the first isolation strip 310 is wrapped around one end of the diaphragm 200, and the second isolation strip 320 is wrapped around the other end of the diaphragm 200. Specifically, an isolation strip 300 is provided between the starting end 100a and the ending end 100b of the electrode winding and the diaphragm 200, as in the previous embodiment. At the same time, the isolation strip 300 is also attached to the end face and the other surface of the diaphragm 200. That is, a complete isolation strip 300 can be used, starting from between the diaphragm 200 and the starting end 100a of the electrode winding, and pasted around the end face and the other surface of the diaphragm 200 to achieve the effect of wrapping the end of the diaphragm 200.

[0051] Continue reading Figure 2In this embodiment, the isolation strip 300 includes a first isolation strip 310 and a second isolation strip 320. The first isolation strip 310 covers the winding start end 100a of the electrode 100; the second isolation strip 320 covers the winding end end 100b of the electrode 100.

[0052] In this embodiment, the insulating strip 300 is directly wrapped around the cut end of the electrode 100 to form a comprehensive protective structure. Unlike the previous embodiments, the insulating strip 300 in this embodiment not only covers the contact surface between the electrode 100 and the diaphragm 200, but also completely wraps around the edge area of ​​the electrode 100, providing more comprehensive isolation and protection.

[0053] Specifically, in this embodiment, the first insulating strip 310 and the second insulating strip 320 can be affixed to the winding start end 100a and winding end end 100b of the electrode 100, similar to stickers. This sticker-like insulating strip 300 can be pre-prepared to an appropriate size and shape and directly affixed to the corresponding position on the electrode 100 before the cell winding assembly. The insulating strip 300 can adopt a U-shaped design, covering one side of the electrode 100 to the edge and then to the other side, forming complete edge protection. This covering design ensures that all areas of the electrode 100 edge that may generate burrs are effectively isolated, preventing damage to the separator 200 in any direction.

[0054] Of course, in other embodiments, the initial shape of the first insulating strip 310 and the second insulating strip 320 can be liquid. The first insulating strip 310 is attached to the starting end 100a of the winding of the electrode 100, and the second insulating strip 320 is attached to the ending end 100b of the winding of the electrode 100. The liquid material can be hot melt adhesive, UV-curable adhesive, or other curable insulating material. This liquid material can be precisely applied to the edge of the electrode 100 by coating, spraying, dispensing, etc., and then a strong insulating layer is formed by heat treatment, UV irradiation, or natural curing. The advantage of this method is that the liquid material can better penetrate and fill the tiny gaps and irregular structures at the edge of the electrode 100, forming a seamless protective layer after curing, providing a tighter coating effect.

[0055] Furthermore, the liquid insulating material can automatically adjust to the actual shape of the electrode 100 edge before curing, adapting to possible slight differences between different batches of electrode 100 and achieving a more customized protective effect. This method is particularly suitable for large-scale production scenarios, enabling highly efficient and consistent application of the insulating strip 300 through automated equipment.

[0056] The encapsulated isolation strip 300 design in this embodiment, whether using pre-made stickers or liquid-cured methods, can provide more comprehensive protection than simple covering, effectively preventing any part of the edge of the electrode 100 from directly contacting the separator 200, thereby minimizing the risk of internal short circuits and improving the safety performance of the battery cell.

[0057] See Figure 4 In this embodiment, the electrode 100 is arranged in segments, and each segment of the electrode 100 is provided with an isolation strip 300 at both ends.

[0058] Due to the processing technology, the electrode 100 needs to be cut to a fixed length during the winding process. If the isolation tape 300 is attached to both ends of each section of electrode 100, the process will be very complicated, increasing production time and cost, and it will also be difficult to guarantee the consistency of the attachment accuracy.

[0059] This embodiment employs a highly efficient continuous processing method. Specifically, the raw material electrode 100 is first cut into multiple segments of a fixed length. Then, adjacent segments of electrode 100 are spaced approximately 3-5 cm apart, and within this space, an insulating strip 300 is used to bond the two segments together, forming a continuous structure. Finally, the insulating strip 300 is cut in the middle. This method allows for simultaneous protection of two segments of electrode 100 with the insulating strip 300 in a single cutting operation: both the tail end of the first segment and the head end of the second segment are protected by the insulating strip 300.

[0060] This process can be carried out continuously. After processing two sections of electrode 100, the connection between the next section of electrode 100 and the previous section is processed in the same way. This ensures that both ends of all sections of electrode 100 are protected by the insulating strip 300. This continuous processing method significantly improves production efficiency, reduces the number of processes, and ensures the accuracy and consistency of the insulating strip 300 attachment position.

[0061] See Figure 1 In this embodiment, the length of the isolation strip 300 is 8-16 mm; the thickness of the isolation strip 300 is 10-20 μm.

[0062] In this embodiment, the length of the isolation strip 300 is 8–16 mm, sufficient to cover the winding start end 100a and winding end end 100b. The length A (A mm) of the isolation strip 300 can be 8 mm, 10 mm, 12 mm, 14 mm, or 16 mm. The thickness of the isolation strip 300 is 10–20 μm, sufficient to cover the length of the burr. The thickness B (B μm) of the isolation strip 300 can be 10 μm, 16 μm, or 20 μm. This embodiment conducted 15 sets of example tests and 2 sets of comparative experiments on different size specifications of the isolation strip 300. The specific data are shown in the table below:

[0063]

[0064]

[0065] As can be seen from Examples 1-15 and Comparative Examples 1-2 above, A is between 8-16mm and B is between 10-20μm, the cell has good safety performance, and there is no 200 melting hole phenomenon in the diaphragm after cycling.

[0066] Test methods and equipment: At an ambient temperature of 25℃, the lithium-ion battery was disassembled, and the positive electrode 100, negative electrode 100, and separator 200 were removed. The adhesive tape attached to the separator 200 was checked to see if it had fallen off.

[0067] When the length of the separator 300 is less than 8 mm (e.g., 6 mm in Comparative Example 1), it cannot completely cover the burr area at the edge of the electrode 100, leading to melting holes in the separator 200 during cycling. Similarly, when the separator 300 is not used at all (Comparative Example 2), the same melting hole problem occurs. In contrast, all embodiments with separator 300 lengths in the range of 8-16 mm and thicknesses in the range of 10-20 μm exhibit excellent performance, completely covering the edge of the electrode 100 and effectively preventing melting holes in the separator 200 during battery cycling.

[0068] Furthermore, the isolation strip 300 is an insulating adhesive layer. In this embodiment, the insulating adhesive layer can be hot melt adhesive, green adhesive, or yellow adhesive, etc. Taking hot melt adhesive as an example, hot melt adhesive is an adhesive material that is solid at room temperature, softens and melts when heated to a certain temperature, and then quickly solidifies after cooling.

[0069] Specifically, the hot melt adhesive material selected in this embodiment has good insulation properties and flexibility, and can remain stable in high-temperature environments without decomposing or releasing harmful substances. The thickness of the hot melt adhesive insulating tape 300 remains between 10-20 μm, and the length is 8-16 mm, consistent with the dimensional parameters in the aforementioned embodiments.

[0070] Hot melt adhesive has excellent adhesion properties, which can firmly adhere to the surface of electrode 100 and is not easy to fall off during long-term use of the battery. Secondly, after the hot melt adhesive softens when heated, it can penetrate into the tiny gaps and irregular structures on the surface of electrode 100, and form a seamless protective layer after cooling and solidification, providing a more comprehensive isolation effect. In addition, the hot melt adhesive material has a certain degree of self-adaptability, which can maintain good elastic deformation ability during the expansion and contraction of the battery during cycling, and will not crack due to repeated stress.

[0071] See Figure 1 In this embodiment, the first isolation strip 310 extends 2-5 mm beyond the starting end 100a of the electrode 100, and the second isolation strip 320 extends 2-5 mm beyond the ending end 100b of the electrode 100.

[0072] In this embodiment, the insulating strip 300 not only covers the cut edge of the electrode 100, but also extends 2-5 mm outward from the starting end 100a and the ending end of the electrode 100, respectively. Figure 1 As shown in the diagram, C. For example, when the insulating strip 300 extends 2mm beyond the edge of the electrode 100, it provides basic edge protection. This moderate extension completely covers any burrs that may be present at the edge of the electrode 100 without excessively increasing the size and weight of the cell. The design extending beyond 2mm is suitable for small cells with strict space and weight requirements, such as mobile phone batteries and wearable device batteries.

[0073] When the isolation band 300 extends 3mm beyond the edge of the electrode 100, it provides more comprehensive protection. This moderate extension not only effectively covers the burr area but also provides sufficient protection margin for minor displacements that may occur in the electrode 100 during cycling.

[0074] When the isolation strip 300 extends 5mm beyond the edge of the electrode 100, it provides maximum safety. This significant extension ensures adequate protection even under extreme conditions such as high temperature, high pressure, and severe vibration. Even if the electrode 100 undergoes significant displacement or deformation during cycling, the 5mm extension of the isolation strip 300 still ensures complete isolation of the burr area.

[0075] Through system testing and analysis of different extension lengths, this embodiment determines the optimal range for the isolation strip 300 to extend 2-5mm beyond the edge of the electrode 100, providing flexible selection space for cell design in different application scenarios.

[0076] See Figure 5 In this embodiment, the electrode 100 includes a positive electrode 110 and a negative electrode 120, and the separator 200 is disposed between the positive electrode 110 and the negative electrode 120 to separate the positive electrode 110 and the negative electrode 120.

[0077] The first isolation strip 310 includes a first sub-isolation strip 311 and a second sub-isolation strip 312. The first sub-isolation strip 311 covers the winding start end 110a of the positive electrode sheet, and the second sub-isolation strip 312 is disposed between the separator 200 and the winding start end 120a of the negative electrode sheet.

[0078] The second isolation strip 320 includes a third sub-isolation strip 323 and a fourth sub-isolation strip 324. The third sub-isolation strip 323 covers the winding end 110b of the positive electrode sheet, and the fourth sub-isolation strip 324 is disposed between the separator 200 and the winding end 120b of the negative electrode sheet.

[0079] In this embodiment, the isolation strip 300 can be configured in a hybrid manner, that is, different isolation strategies are used for different positions of the electrode 100. Specifically, for the positive electrode 110, due to its material properties and the special nature of its burr morphology, a wrapping isolation method is adopted, that is, the first sub-isolation strip 311 completely wraps the starting end 110a of the positive electrode winding, and the third sub-isolation strip 323 completely wraps the ending end 110b of the positive electrode winding, forming all-round protection. This wrapping design can ensure that all areas on the edge of the positive electrode 110 that may generate burrs are effectively isolated, which is particularly suitable for dealing with the small burrs that are easily generated by the aluminum foil current collector of the positive electrode 110.

[0080] For the negative electrode 120, due to the characteristics of its copper foil current collector, the burrs are usually relatively coarse but few in number. A simple covering isolation method is adopted, that is, the second sub-isolation strip 312 is set between the separator 200 and the winding start end 120a of the negative electrode, and the fourth sub-isolation strip 324 is set between the separator 200 and the winding end end 120b of the negative electrode. This design can effectively isolate the burrs of the negative electrode 120 and minimize the use of additional materials, thus maintaining the energy density of the cell.

[0081] This hybrid configuration fully considers the different characteristics and safety requirements of the positive and negative electrode plates 120, achieving targeted protection and optimizing material usage and manufacturing processes while ensuring cell safety.

[0082] Regarding the key dimensional relationships during the battery cell winding process, the following related formulas exist:

[0083] The diaphragm 200 pre-wound is nπd longer than the negative electrode sheet 120 pre-wound (n is the number of turns, between 3 and 5, and d is the diameter of the circle), ensuring sufficient insulation protection in the innermost layer of the cell to prevent direct contact between the positive and negative electrodes at the initial position inside.

[0084] The negative electrode 120 is longer than the positive electrode 110 by mπd (m is the number of turns, between 2 and 3 turns, and d is the diameter of the circle). This is called "excessive negative electrode design". The purpose is to prevent lithium ions from depositing at the edge of the positive electrode during charging and forming lithium dendrites, thereby improving the safety performance and cycle life of the battery cell.

[0085] The adhesive tape covering the pre-wound section of the separator 200 (i.e., the insulating tape 300) must be n / m*d longer than the positive electrode insertion point (n > m). This ensures that the insulating tape 300 of sufficient length is used to protect the critical positive electrode insertion point of the cell, forming multiple safety safeguards. Since n is greater than m, this ratio guarantees that the coverage length of the insulating tape 300 is always greater than the necessary minimum length, providing additional safety margins.

[0086] This utility model further proposes a lithium-ion battery, including a casing and a battery cell as described in the foregoing embodiments. The specific structure of the battery cell is as described in the foregoing embodiments. Since the lithium-ion battery adopts all the technical solutions of all the foregoing embodiments, it has at least all the technical effects brought about by the technical solutions of the foregoing embodiments, and will not be described in detail here. The casing forms a mounting cavity, and the battery cell is disposed within the mounting cavity.

[0087] This invention further applies the aforementioned cell technology to a complete lithium-ion battery product, resulting in a lithium-ion battery with high safety performance. The lithium-ion battery comprises two main parts: an outer casing and an inner cell. The casing has a mounting cavity for accommodating the cell, which is then installed within the mounting cavity.

[0088] The casing can be made of different materials and shapes depending on the application requirements, such as metal casing (e.g., aluminum casing, steel casing), plastic casing, or flexible packaging. Regardless of the casing form, the internal battery cell adopts the structural design described in the aforementioned embodiments, that is, an isolation strip 300 is provided at the winding start end 100a and winding end end 100b of the electrode 100, which effectively solves the problem of burrs on the edge of the electrode 100 puncturing the separator 200.

[0089] The present invention further proposes an electrical device, including the lithium-ion battery of the aforementioned embodiment.

[0090] In this embodiment, the present invention applies the aforementioned high-safety-performance lithium-ion battery to various electrical devices, forming a terminal product with higher safety and reliability. These electrical devices can be consumer electronics (such as smartphones, tablets, laptops, smartwatches, etc.), power tools (such as electric drills, chainsaws, etc.), electric vehicles (such as electric bicycles, electric motorcycles, electric cars, etc.), outdoor equipment (such as portable power supplies, lighting equipment, etc.), or large-scale energy storage systems, etc.

[0091] Thanks to the lithium-ion battery proposed in this invention, this electrical device offers significant advantages in safety performance. Specifically, because both the starting end 100a and the ending end 100b of the electrode 100 inside the battery cell are equipped with insulating strips 300, the problem of burrs on the edge of the electrode 100 puncturing the separator 200 is effectively prevented, fundamentally eliminating the risk of thermal runaway caused by internal short circuits. This allows the electrical device to maintain a stable and safe operating state even under extreme conditions such as high-temperature environments, prolonged use, frequent charging and discharging, or severe vibration.

[0092] The above description is only a part or preferred embodiment of this utility model. Neither the text nor the drawings should limit the scope of protection of this utility model. All equivalent structural transformations made using the content of this utility model specification and drawings under the overall concept of this utility model, or direct / indirect applications in other related technical fields, are included within the scope of protection of this utility model.

Claims

1. A battery cell, comprising an electrode and a separator, wherein the separator is stacked and wound with the electrode, and the electrode includes a winding start end and a winding end; characterized in that, Both the starting end and the ending end of the winding are provided with isolation strips to separate the diaphragm from the electrode.

2. The battery cell according to claim 1, characterized in that, The insulating strip includes a first insulating strip and a second insulating strip. The first insulating strip is disposed between the starting end of the winding of the diaphragm and the electrode sheet, and the second insulating strip is disposed between the ending end of the winding of the diaphragm and the electrode sheet.

3. The battery cell according to claim 2, characterized in that, The first isolation strip and the second isolation strip respectively cover the first and second ends of the diaphragm.

4. The battery cell according to claim 1, characterized in that, The insulating strip includes a first insulating strip and a second insulating strip, wherein the first insulating strip covers the starting end of the winding of the electrode sheet; and the second insulating strip covers the ending end of the winding of the electrode sheet.

5. The battery cell according to claim 1, characterized in that, The length of the isolation strip is 8–16 mm; the thickness of the isolation strip is 10–20 μm.

6. The battery cell according to any one of claims 1 to 5, characterized in that, The isolation strip is an insulating adhesive layer.

7. The battery cell according to claim 2, characterized in that, The first insulating strip extends 2-5 mm beyond the starting end of the winding of the electrode sheet, and the second insulating strip extends 2-5 mm beyond the ending end of the winding of the electrode sheet.

8. The battery cell according to claim 2 or 3, characterized in that, The electrode includes a positive electrode and a negative electrode, and the separator is disposed between the positive electrode and the negative electrode to separate the positive electrode and the negative electrode; The first insulating strip includes a first sub-insulating strip and a second sub-insulating strip. The first sub-insulating strip covers the starting end of the winding of the positive electrode sheet, and the second sub-insulating strip is disposed between the separator and the starting end of the winding of the negative electrode sheet. The second insulating strip includes a third sub-insulating strip and a fourth sub-insulating strip. The third sub-insulating strip covers the winding end of the positive electrode sheet, and the fourth sub-insulating strip is disposed between the separator and the winding end of the negative electrode sheet.

9. A lithium-ion battery, characterized in that, It includes a housing and a battery cell as described in any one of claims 1 to 8, wherein the housing has a mounting cavity and the battery cell is disposed within the mounting cavity.

10. An electrical appliance, characterized in that, Including the lithium-ion battery as described in claim 9.

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