Battery cell and lithium battery
By designing that the spacing between the positive and negative electrodes of the battery cell is greater than one-third of the outer diameter of the coil core, the problem of short circuit and fire in the needle-punching test is solved, and the test pass rate and safety performance are improved.
Patent Information
- Application Number
- CN202421008546.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-10
- Publication Date
- 2025-04-04
- Estimated Expiration
- 2034-05-10
AI Technical Summary
During needle-punching test, lithium batteries are prone to short-circuit because the positive and negative electrode ears are pierced by steel needles at the same time, which causes rapid temperature rise, fire or explosion, resulting in test failure.
A battery cell is designed, wherein the positive electrode ear and the negative electrode ear are connected to the coil core, and the spacing between the positive projection of the positive electrode ear on the axial end surface of the core and the positive projection of the negative electrode ear on the axial end surface is greater than one-third of the outer diameter of the coil core, thereby reducing the probability that the steel needle pierces the positive electrode ear and the negative electrode ear at the same time during needle puncture test.
By increasing the spacing between the positive electrode ear and the negative electrode ear, the possibility of steel needle piercing at the same time during needle puncture test is reduced, thereby improving the pass rate of the needle puncture test of lithium batteries and improving the safety performance of lithium batteries.
Smart Images
Figure CN222720483U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of lithium batteries, in particular to a battery cell and a lithium battery with a higher needle puncture test pass rate. Background Art
[0002] Lithium batteries have advantages such as high voltage, high capacity, and long cycle, and have been widely used. However, with the increase in battery safety accidents of electronic products, consumers have higher requirements for the battery safety of electronic products. The needle penetration test is a test method for the safety performance of lithium batteries. Due to structural reasons, when lithium batteries are subjected to needle penetration tests, it is easy for the positive and negative ears to be pierced by the steel needle at the same time, resulting in an internal short circuit in the battery cell, causing the battery cell temperature to rise rapidly, causing the battery to catch fire or even explode, and then leading to the failure of the needle penetration test. Utility Model Content
[0003] The main purpose of the utility model is to provide a battery cell, aiming to solve the problem of low pass rate of lithium battery needle puncture test.
[0004] To achieve the above-mentioned purpose, one aspect of the utility model proposes a battery cell, including a winding core, a positive electrode tab and a negative electrode tab, the positive electrode tab and the negative electrode tab are respectively connected to the winding core, and the distance between the orthographic projection of the positive electrode tab on the axial end face of the winding core and the orthographic projection of the negative electrode tab on the axial end face is greater than one third of the outer diameter of the winding core.
[0005] In some embodiments, the spacing between the orthographic projection of the positive electrode tab on the axial end surface of the winding core and the orthographic projection of the negative electrode tab on the axial end surface is greater than or equal to half of the outer diameter of the winding core and less than or equal to the outer diameter of the winding core.
[0006] In some embodiments, the distance from at least one of the orthographic projection of the positive electrode tab on the axial end face of the core and the orthographic projection of the negative electrode tab on the axial end face to the central axis of the core is greater than one-third of the outer diameter of the core and less than or equal to one-half of the outer diameter of the core.
[0007] In some embodiments, a distance between an orthographic projection of the positive electrode tab on the axial end surface of the winding core and an orthographic projection of the negative electrode tab on the axial end surface is greater than 5 mm and less than or equal to 13 mm.
[0008] In some embodiments, a distance between an orthographic projection of the positive electrode tab on the axial end surface of the winding core and an orthographic projection of the negative electrode tab on the axial end surface is greater than 13 mm and less than or equal to 26 mm.
[0009] In some embodiments, at least one of the distance from the orthogonal projection of the positive electrode tab on the axial end surface of the winding core to the central axis of the winding core and the distance from the orthogonal projection of the negative electrode tab on the axial end surface to the central axis of the winding core is greater than 5 mm.
[0010] In some embodiments, the distance from the orthographic projection of the positive electrode tab on the axial end surface of the winding core to the central axis of the winding core is greater or less than the distance from the orthographic projection of the negative electrode tab on the axial end surface to the central axis of the winding core.
[0011] In some embodiments, the outer diameter of the winding core is 15 mm to 26 mm.
[0012] In some embodiments, the outer profile of the winding core is cylindrical.
[0013] In some embodiments, the winding core is formed by winding a positive electrode sheet, a separator, and a negative electrode sheet stacked in sequence, the positive electrode tab is connected to the positive electrode sheet, and the negative electrode tab is connected to the negative electrode sheet.
[0014] In another aspect of the present invention, a lithium battery is provided. The lithium battery comprises a housing and the battery cell as described above, wherein the battery cell is disposed in the housing.
[0015] Compared with the existing battery cells, the spacing between the positive electrode tab on the axial end face of the winding core and the negative electrode tab on the axial end face of the battery cell of the utility model is greater than one third of the outer diameter of the winding core. Since the diameter of the steel needle used in the puncture test of lithium batteries ranges from 1mm to 5mm, and the diameter of the conventional winding core ranges from 15mm to 26mm, in the battery cell structure, the spacing between the positive electrode tab on the axial end face of the winding core and the negative electrode tab on the axial end face is greater than one third of the outer diameter of the winding core, which can ensure sufficient avoidance space between the positive electrode tab and the negative electrode tab, thereby reducing the problem of the steel needle piercing the positive electrode tab and the negative electrode tab at the same time during the puncture test, thereby improving the pass rate of the puncture test and improving the safety performance of the lithium battery using the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 This is a schematic diagram of the battery structure of an embodiment of the utility model;
[0017] Figure 2 This is a schematic diagram of the battery cell structure of another embodiment of the utility model;
[0018] Figure 3 This is a schematic diagram of a battery cell structure according to another embodiment of the utility model.
[0019] Description of Figure Numbers:
[0020] Winding core 100; positive electrode sheet 110; separator 120; negative electrode sheet 130; positive electrode tab 200; negative electrode tab 300.
[0021] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION
[0022] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the scheme in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.
[0023] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, top, bottom, side...) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.
[0024] It should also be noted that when an element is referred to as being "fixed on" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element at the same time. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element at the same time.
[0025] In addition, the descriptions involving "first", "second", etc. in the embodiments of the present invention are only for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features.
[0026] Regarding the technical defects existing in relevant technologies, such as Figure 1 As shown, this embodiment provides a battery cell, a battery cell winding core 100, a positive electrode tab 200 and a negative electrode tab 300 of this embodiment. The winding core 100 is formed by winding a positive electrode sheet 110, a separator 120 and a negative electrode sheet 130 stacked in sequence. The positive electrode tab 200 is connected to the positive electrode sheet 110, and the negative electrode tab 300 is connected to the negative electrode sheet 130.
[0027] Among them, the outer diameter of the core 100 is 15mm to 26mm. The distance between the orthographic projection of the positive electrode tab 200 on the axial end face of the core 100 and the orthographic projection of the negative electrode tab 300 on the axial end face is greater than one-third of the outer diameter of the core 100. It should be noted that the definition of the outer diameter of the core 100 varies according to actual conditions. When the core 100 is cylindrical, the outer diameter of the core 100 refers to the diameter of the core 100. When the core 100 is an elliptical cylinder, the outer diameter of the core 100 refers to the minimum diameter of the core 100. It should be noted that the following embodiments are described using the cylindrical core 100 as an example.
[0028] Since the diameter of the steel needle used in the puncture test of lithium batteries ranges from 1mm to 5mm, and the diameter of the conventional winding core 100 ranges from 15mm to 26mm, in the battery cell structure, the distance between the orthographic projection of the positive electrode tab 200 on the axial end face of the winding core 100 and the orthographic projection of the negative electrode tab 300 on the axial end face is greater than one-third of the outer diameter of the winding core 100, thereby ensuring sufficient avoidance space between the positive electrode tab 200 and the negative electrode tab 300, thereby reducing the problem of the steel needle piercing the positive electrode tab 200 and the negative electrode tab 300 at the same time during the puncture test.
[0029] Exemplarily, according to actual design requirements, for example: when the positive electrode tab 200 or the negative electrode tab 300 is connected to the outermost periphery of the winding core 100, taking the diameter of the winding core 100 as an example, the distance between the orthographic projection of the positive electrode tab 200 on the axial end face of the winding core 100 and the orthographic projection of the negative electrode tab 300 on the axial end face is greater than 13 mm and less than or equal to 26 mm.
[0030] Another example: Figure 2 As shown, when the positive electrode tab 200 or the negative electrode tab 300 is connected to a region relatively close to the central axis of the winding core 100, in order to maximize the spacing between the positive projection of the positive electrode tab 200 on the axial end surface of the winding core 100 and the negative electrode tab 300 on the axial end surface, the spacing between the positive projection of the positive electrode tab 200 on the axial end surface of the winding core 100 and the negative electrode tab 300 on the axial end surface is greater than or equal to one-half of the outer diameter of the winding core 100 and less than or equal to the outer diameter of the winding core 100. In this way, even if the diameter of the winding core 100 is the minimum 15 mm, the spacing between the positive projection of the positive electrode tab 200 on the axial end surface of the winding core 100 and the negative electrode tab 300 on the axial end surface is between 7.5 mm and 15 mm, so that the positive electrode tab 200 and the negative electrode tab 300 are sufficient to avoid the steel needle during the needle penetration test.
[0031] In some embodiments, the distance from at least one of the orthographic projection of the positive electrode tab 200 on the axial end surface of the core 100 and the orthographic projection of the negative electrode tab 300 on the axial end surface to the central axis of the core 100 is greater than one-third of the outer diameter of the core 100 and less than or equal to one-half of the outer diameter of the core 100. When the diameter of the core 100 is the smallest specification of 15 mm, the spacing between the orthographic projection of the positive electrode tab 200 on the axial end surface of the core 100 and the orthographic projection of the negative electrode tab 300 on the axial end surface is greater than 5 mm and less than or equal to 7.5 mm. When the diameter of the core 100 is the largest specification of 26 mm, the spacing between the orthographic projection of the positive electrode tab 200 on the axial end surface of the core 100 and the orthographic projection of the negative electrode tab 300 on the axial end surface is greater than 8 mm and less than or equal to 13 mm.
[0032] In some embodiments, since the puncture test of the lithium battery is to insert the steel needle from the center of the lithium battery, in order to avoid the steel needle, at least one of the distance from the positive electrode tab 200 on the axial end face of the core 100 to the central axis of the core 100 and the distance from the negative electrode tab 300 on the axial end face to the central axis of the core 100 is greater than 5 mm. According to actual design requirements, the distance from the positive electrode tab 200 on the axial end face of the core 100 to the central axis of the core 100 is greater than the distance from the negative electrode tab 300 on the axial end face to the central axis of the core 100. Of course, it can also be set that the distance from the positive electrode tab 200 on the axial end face of the core 100 to the central axis of the core 100 is less than the distance from the negative electrode tab 300 on the axial end face to the central axis of the core 100.
[0033] In some embodiments, Figure 3 As shown, in order to maximize the avoidance space between the positive electrode tab 200 and the negative electrode tab 300, the positive electrode tab 200 and the negative electrode tab 300 are both connected to the positive electrode sheet 110 and the negative electrode sheet 130 on the periphery of the winding core 100, so that the orthographic projection of the positive electrode tab 200 on the axial end face of the winding core 100 and the orthographic projection of the negative electrode tab 300 on the axial end face are arranged relatively in the radial direction of the winding core 100. In the present embodiment, the spacing between the orthographic projection of the positive pole tab 200 on the axial end face of the winding core 100 and the orthographic projection of the negative pole tab 300 on the axial end face is close to the outer diameter of the winding core 100, thereby maximizing the avoidance space between the positive pole tab 200 and the negative pole tab 300. Therefore, the winding core 100 of the present embodiment adopts the smallest specification of 15mm, and the avoidance space between the positive pole tab 200 and the negative pole tab 300 is also nearly 15mm. Therefore, even if a 5mm diameter steel needle is used for the puncture test, since the avoidance space between the positive pole tab 200 and the negative pole tab 300 is much larger than the diameter of the steel needle, the battery cell of the present embodiment can also pass the puncture test smoothly.
[0034] In summary, when designing the battery cell structure, the embodiments of the utility model adjust the positions of the positive and negative electrode tabs so that the horizontal spacing between the positive and negative electrode tabs after winding is greater than the diameter of the test steel needle, thereby reducing the probability of the steel needle penetrating the positive and negative electrode tabs at the same time during the puncture test, thereby improving the pass rate of the puncture test and the safety performance of the lithium battery.
[0035] In some embodiments, a lithium battery is provided. The lithium battery of this embodiment uses the battery cell of the above embodiment, so as to have a higher pass rate of the needle puncture test and improve the safety performance of the electronic device (such as a tablet computer or a smart phone, etc.) using the lithium battery.
[0036] The above description is only a partial or preferred embodiment of the present invention. Neither the text nor the drawings can limit the scope of protection of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the overall concept of the present invention, or direct / indirect application in other related technical fields are included in the scope of protection of the present invention.
Claims
1. A battery cell, comprising a winding core, a positive electrode tab and a negative electrode tab, wherein the positive electrode tab and the negative electrode tab are respectively connected to the winding core, characterized in that: The distance between the orthographic projection of the positive electrode tab on the axial end surface of the winding core and the orthographic projection of the negative electrode tab on the axial end surface is greater than one third of the outer diameter of the winding core.
2. The battery cell according to claim 1, characterized in that: The spacing is greater than or equal to one half of the outer diameter of the winding core and less than or equal to the outer diameter of the winding core.
3. The battery cell according to claim 1, characterized in that: The distance from at least one of the orthographic projection of the positive electrode tab on the axial end face of the core and the orthographic projection of the negative electrode tab on the axial end face to the central axis of the core is greater than one-third of the outer diameter of the core and less than or equal to one-half of the outer diameter of the core.
4. The battery cell according to claim 1, characterized in that: The spacing is greater than 5 mm and less than or equal to 13 mm.
5. The battery cell according to claim 1, characterized in that: The spacing is greater than 13 mm and less than or equal to 26 mm.
6. The battery cell according to claim 1, characterized in that: At least one of the distance from the orthographic projection of the positive electrode tab on the axial end surface of the winding core to the central axis of the winding core and the distance from the orthographic projection of the negative electrode tab on the axial end surface to the central axis of the winding core is greater than 5 mm.
7. The battery cell according to claim 6, characterized in that: The distance between the orthographic projection of the positive electrode tab on the axial end surface of the winding core and the central axis of the winding core is greater than or less than the distance between the orthographic projection of the negative electrode tab on the axial end surface and the central axis of the winding core.
8. The battery cell according to any one of claims 1 to 7, characterized in that: The outer contour of the winding core is cylindrical; and / or the outer diameter of the winding core is 15 mm to 26 mm.
9. The battery cell according to any one of claims 1 to 7, characterized in that: The winding core is formed by winding a positive electrode sheet, a separator, and a negative electrode sheet stacked in sequence, the positive electrode tab is connected to the positive electrode sheet, and the negative electrode tab is connected to the negative electrode sheet.
10. A lithium battery, characterized in that: The invention comprises a shell and a battery cell as claimed in any one of claims 1 to 9, wherein the battery cell is arranged in the shell.