Lithium battery roll core

Abstract

The utility model discloses a lithium battery roll core which comprises an insulating diaphragm, a negative plate and a positive plate which are sequentially coated from outside to inside, the negative plate comprises a negative electrode material area coated with an active material layer and a negative electrode lug, and the positive plate comprises a positive electrode material area coated with an active material layer and a positive electrode lug; and the bottom of the positive electrode lug is higher than the top of the negative electrode material area. According to the utility model, by optimizing the structural design of the lithium battery roll core, burrs on the tab of the positive plate are effectively prevented from puncturing the diaphragm in the battery assembling and using processes, so that the risk of short circuit of the battery is obviously reduced. The improvement not only ensures the stability and the reliability of the battery, but also remarkably improves the service life and the safety performance of the battery, and provides a more reliable power supply solution for application in the fields of new energy automobiles, energy storage and the like.

Description

Technical Field

[0001] The utility model belongs to the technical field of lithium batteries, and particularly relates to a lithium battery core. Background Art

[0002] With the increasing global attention to environmental protection and sustainable development, the new energy industry has entered a golden period of rapid development. Especially in the fields of new energy vehicles and energy storage, lithium-ion batteries have become the core power source and energy storage carrier in these fields due to their excellent performance such as high energy density, long life, and fast charging. However, while bringing convenience, the safety issues of lithium-ion batteries have become increasingly prominent, becoming a key factor restricting their further development and application.

[0003] The safety performance of lithium-ion batteries mainly includes their performance under extreme conditions such as short circuit, overcharging, over-discharging, and high temperature. Among them, short circuit is one of the most common faults of lithium-ion batteries. Once a short circuit occurs, a large amount of heat will be generated inside the battery, triggering thermal runaway of the battery and even potentially causing serious consequences such as fire or explosion.

[0004] During the manufacturing process of lithium-ion batteries, burrs on the battery electrode sheets are a problem that cannot be ignored. Due to limitations in manufacturing processes, burrs will be generated during the cutting, winding, etc. of battery electrode sheets. These burrs are likely to pierce the separator during subsequent battery assembly and use, resulting in direct contact between the positive and negative electrodes, thus triggering a short circuit. Therefore, reducing the short circuit rate of lithium-ion batteries and improving the safety of batteries have become urgent technical problems to be solved in the current new energy industry.

[0005] In response to the above problems, there are currently some technical solutions that attempt to reduce the short circuit rate of lithium-ion batteries by improving manufacturing processes, increasing material purity, optimizing battery structures, etc. However, these methods still have some limitations in practical applications, such as high manufacturing costs, complex processes, and unstable effects. Summary of the Utility Model

[0006] In view of the deficiencies of the prior art, the utility model provides a lithium battery core, and this structure can effectively reduce the short circuit rate during the manufacturing process of lithium-ion batteries.

[0007] The utility model is realized through the following technical solutions:

[0008] A lithium battery core includes an insulating separator, a negative electrode sheet, and a positive electrode sheet that are sequentially coated from the outside to the inside; the negative electrode sheet includes a negative electrode material area coated with an active material layer and a negative electrode tab, and the positive electrode sheet includes a positive electrode material area coated with an active material layer and a positive electrode tab; the bottom height of the positive electrode tab is higher than the top height of the negative electrode material area.

[0009] Among them, the bottom height of the positive electrode tab is higher than the top height of the negative electrode material area, which can effectively prevent the burrs on the positive electrode tab from piercing the separator during battery assembly and use.

[0010] Preferably, the height of the positive electrode tab ≤ 10 mm.

[0011] Preferably, the compaction density of the positive electrode sheet ≤ 2.6 g / cc.

[0012] Preferably, the phase difference between the negative electrode material area and the positive electrode material area ≥ 2.5 mm.

[0013] Preferably, the positive electrode sheet further includes a ceramic area, and the ceramic area is located at the blank space above the positive electrode material area.

[0014] Preferably, the phase difference between the total height of the ceramic area and the positive electrode material area and the height of the negative electrode material area ≥ 0.5 mm.

[0015] The beneficial effects of the present utility model are as follows:

[0016] By optimizing the structural design of the lithium battery core, the present utility model effectively prevents the burrs on the positive electrode tab from piercing the separator during battery assembly and use, thereby significantly reducing the risk of battery short circuit. This improvement not only ensures the stability and reliability of the battery, but also significantly improves the service life and safety performance of the battery, providing a more reliable power supply solution for applications in the fields of new energy vehicles and energy storage. The lithium battery core of the present utility model also has the advantages of simple manufacturing process and controllable cost. Compared with traditional solutions, the present utility model can significantly reduce the short circuit rate without complex adjustment of the manufacturing process or introduction of expensive equipment, so it has higher feasibility and economy in production practice. Description of the Drawings

[0017] Figure 1 is a schematic structural diagram of the lithium battery core of the present utility model;

[0018] Figure 2 is a schematic structural diagram of the lithium battery core before improvement;

[0019] In the figure: 1, separator; 2, negative electrode sheet; 3, positive electrode sheet; 4, negative electrode material area; 5, negative electrode tab; 6, positive electrode material area; 7, positive electrode tab; 8, ceramic area. Detailed Embodiments

[0020] The following further describes the present utility model in detail with reference to the drawings and specific embodiments.

[0021] Embodiment 1

[0022] A lithium battery core, as Figure 1As shown in the figure, it includes an insulating diaphragm 1, a negative electrode sheet 2, and a positive electrode sheet 3 that are sequentially coated from the outside to the inside; the negative electrode sheet 2 includes a negative electrode material area 4 coated with an active material layer and a negative electrode tab 5, and the positive electrode sheet 3 includes a positive electrode material area 6 coated with an active material layer and a positive electrode tab 7; wherein, the bottom height of the positive electrode tab 7 is higher than the top height of the negative electrode material area 4, and the height of the positive electrode tab 7 does not exceed 10 mm.

[0023] And the compaction density of the positive electrode sheet 3 cannot be too high, not higher than 2.6 g / cc, otherwise it is easy to break the tape during the preparation process, resulting in inability to produce, and it will also affect the rate / cycle performance of the battery cell.

[0024] As Figure 1 shown, the height of the laser cut of the positive electrode tab 7 is adjusted to make the height of the positive electrode sheet 3 higher than the height of the negative electrode sheet 2. The structure of the lithium battery core before improvement is as Figure 2 shown, compared with Figure 1 , in this core structure, the height of the laser cut of the positive electrode tab 7 is lower than the height of the negative electrode material area 4. At this time, the laser cut tab will make burrs or molten beads easily pierce the diaphragm 1, resulting in a short circuit of the lithium-ion battery.

[0025] From Figure 1 and Figure 2 comparison, it can be seen that after adjusting the position of the laser cut of the positive electrode tab 7, the height of the positive electrode sheet 3 is higher than the height of the negative electrode sheet 2, thereby effectively reducing the short circuit caused by the laser cut tab.

[0026] In addition, in this embodiment, the phase difference between the negative electrode material area and the positive electrode material area cannot be less than 2.5 mm, so that the negative electrode material area 4 can still wrap the positive electrode material area 6, avoiding the lack of sufficient lithium intercalation sites in the negative electrode during lithium-ion charging, which may cause lithium deposition.

[0027] As Figure 1 shown, in this embodiment, the positive electrode sheet 3 further includes a ceramic area 8 located in the blank area above the positive electrode material area 6. The ceramic area 8 is composed of PVDF (polyvinylidene fluoride) and boehmite mixed in proportion, and the proportion is between 2:8 and 1:9; and, the phase difference between the height of the ceramic area 8 + the positive electrode material area 6 and the height of the negative electrode material area 4 ≥ 0.5 mm.

[0028] The embodiments described above are only a part of the embodiments of the present invention, not all of the embodiments. The detailed description of the embodiments of the present invention is not intended to limit the scope of the present invention claimed, but only represents the selected embodiments of the present invention. The protection scope of the present invention shall be subject to the scope claimed in the claims. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

Claims

1. A lithium battery core, characterized in that: It includes an insulating diaphragm, a negative electrode sheet and a positive electrode sheet which are sequentially coated from the outside to the inside; the negative electrode sheet includes a negative electrode material area coated with an active material layer and a negative electrode tab, and the positive electrode sheet includes a positive electrode material area coated with an active material layer and a positive electrode tab; the bottom height of the positive electrode tab is higher than the top height of the negative electrode material area.

2. A lithium battery roll core according to claim 1, characterized in that: The height of the positive electrode tab is ≤10 mm.

3. A lithium battery roll core according to claim 1, characterized in that: The compaction density of the positive electrode sheet is ≤2.6 g / cc.

4. A lithium battery roll core according to claim 1, characterized in that: The phase difference between the negative electrode material area and the positive electrode material area is ≥2.5mm.

5. The lithium battery roll core according to claim 1, characterized in that: The positive electrode sheet also includes a ceramic area, and the ceramic area is located in the blank area above the positive electrode material area.

6. A lithium battery roll core according to claim 5, characterized in that: The phase difference between the total height of the ceramic area and the positive electrode material area and the height of the negative electrode material area is ≥0.5 mm.

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