A lithium-ion battery cell structure and method of use thereof
By setting electrolyte replenishment holes and insulating encapsulation components on the aluminum-plastic film of lithium-ion battery cells, secondary electrolyte injection and voltage reduction operations are realized, solving the problems of electrolyte consumption and by-product formation, and extending the service life of the battery cells.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHEJIANG LIWINON ENERGY TECHNOLOGY CO LTD
- Filing Date
- 2023-02-14
- Publication Date
- 2026-07-14
AI Technical Summary
During long-term use, the lithium-ion channel impedance of existing lithium-ion battery cells increases due to electrolyte consumption and the formation of by-products, which affects the cell lifespan.
A liquid replenishment hole is set on the aluminum-plastic film and covered with an insulating encapsulation component. The electrolyte is injected a second time through the liquid replenishment hole and combined with the voltage reduction operation to extend the service life of the battery cell.
By using secondary electrolyte injection and voltage reduction, the cycle life of the battery cell was extended, the problems of lithium-ion migration obstruction and by-product formation caused by electrolyte loss were solved, and the cycle capability of the battery cell was improved.
Smart Images
Figure CN116093510B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the technical field of lithium-ion batteries, and more specifically, to a lithium-ion battery cell structure and its usage method. Background Technology
[0002] Lithium-ion batteries have stood out among chemical energy storage devices due to their advantages such as high energy density, no memory effect, long cycle life, and environmental friendliness, attracting widespread attention from industries such as electric vehicles and 3C products. To meet market demand for high energy storage, battery energy density is becoming increasingly higher, making the improvement of cell cycle life a key issue of current industry focus.
[0003] Reference Figure 1 Existing battery cells mainly consist of electrodes (not shown in the figure), electrolyte (not shown in the figure), an aluminum-plastic film that houses the electrodes and electrolyte, and positive and negative tabs that connect to the electrodes. Considering the position of the tabs, existing battery cells generally use a packaging method with... Figure 2 The aluminum-plastic film shown is used for encapsulation with deep and shallow pits.
[0004] During long-term use, the loss of positive and negative electrode materials and the consumption of electrolyte are the main factors causing the degradation of battery cell life. On the one hand, during the cell formation process, the reaction between the negative electrode material and the electrolyte produces a passivated SEI film, which continuously consumes electrolyte and reduces the conductive medium for lithium ion movement in the cell. This increases the impedance of the lithium ion channel, making it insufficient for the migration of more lithium ions, thus leading to a significant reduction in cell capacity. On the other hand, the cell material is subjected to high-voltage cycling for a long time, and the electrolyte will accelerate the formation of the by-product SEI film, which has a significant impact on the cell life.
[0005] Therefore, improvements are needed to existing lithium battery cells. Summary of the Invention
[0006] To address the shortcomings of existing technologies, this invention provides a lithium-ion battery cell structure and its usage method, which aims to improve the service life of lithium-ion batteries.
[0007] The present invention discloses a lithium-ion battery cell structure, comprising: a positive electrode tab; a negative electrode tab; an aluminum-plastic film having a shallow pit surface and a deep pit surface, wherein a liquid replenishment hole is formed on the shallow pit surface; and an insulating encapsulation component covering the liquid replenishment hole and completely sealing the liquid replenishment hole.
[0008] Preferably, the replenishment hole is a round hole.
[0009] Preferably, the insulating encapsulation component is adhesive tape.
[0010] Preferably, the distance between the liquid replenishment hole and the positive electrode tab is less than the distance between the liquid replenishment hole and the negative electrode tab.
[0011] Preferably, the diameter of the replenishment hole is 0.3-0.5 mm.
[0012] Preferably, the insulating encapsulation component has a circular, rectangular, or elliptical structure.
[0013] This invention also discloses a method for using a lithium-ion battery cell structure to maintain any of the above-mentioned lithium-ion battery cell structures, comprising the following steps:
[0014] Step 1: Reduce the voltage of the battery cell;
[0015] Step 2: Open the insulating encapsulation of the battery cell in the glove box to expose the liquid replenishment hole;
[0016] Step 3: Use a syringe to inject electrolyte into the battery cell a second time through the electrolyte filling hole. After the electrolyte filling is completed, reseal the electrolyte filling hole.
[0017] Preferably, the steps are performed using battery cells that have been cycled more than 1000 times and / or have a capacity of less than 85%.
[0018] Preferably, the electrolyte is injected a second time at 50-60% of the original standard electrolyte volume of the battery cell.
[0019] Preferably, the battery cell with the liquid replenishment hole sealed is left to stand at room temperature for more than 12 hours before the voltage reduction step is performed.
[0020] The beneficial effects of this application are as follows: the combination of the electrolyte filling hole and the insulating encapsulation makes the cell an internally closable structure. After the cell has undergone cycle aging, by opening the insulating encapsulation and injecting electrolyte into the cell through the electrolyte filling hole for a second time, combined with the operation of reducing the voltage of the cell, the problems of lithium ion migration being hindered due to electrolyte loss and the formation of by-products being accelerated by high voltage are solved, thereby increasing the cell's cycle capacity and cycle life. Moreover, this structure and method are low in cost, highly operable, and widely applicable, providing a better way to extend the life of consumer batteries. Attached Figure Description
[0021] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:
[0022] Figure 1 This is a schematic diagram of the structure of an existing battery cell in the background art;
[0023] Figure 2This is a schematic diagram of the structure of the aluminum-plastic film used for encapsulating battery cells in the background art;
[0024] Figure 3 This is a schematic diagram of the cell structure of the lithium-ion battery of the present invention;
[0025] Figure 4 This is a schematic diagram of the aluminum-plastic film structure in the cell structure of the lithium-ion battery of the present invention;
[0026] Figure 5 This is a comparison chart of capacity retention rates between cells in normal cycling and cells that have undergone secondary electrolyte injection.
[0027] Explanation of reference numerals in the attached diagram: 1. Positive tab; 2. Negative tab; 3. Aluminum-plastic film; 31. Shallow pit surface; 311. Liquid replenishment hole; 32. Deep pit surface; 4. Insulating encapsulation component. Detailed Implementation
[0028] The following drawings disclose several embodiments of the present invention. For clarity, many practical details will be described in the following description. However, it should be understood that these practical details are not intended to limit the invention. That is, in some embodiments of the invention, these practical details are not essential. Furthermore, for the sake of simplicity, some conventional structures and components will be shown in the drawings in a simple schematic manner.
[0029] It should be noted that all directional indications in the embodiments of the present invention, such as up, down, left, right, front, back, etc., are only used to explain the relative positional relationship and movement of the components in a specific posture as shown in the attached figure. If the specific posture changes, the directional indication will also change accordingly.
[0030] Furthermore, in this invention, the use of terms such as "first," "second," etc., is for descriptive purposes only and does not specifically refer to any order or sequence, nor is it intended to limit the invention. They are merely used to distinguish items or operations described using the same technical terms and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If a combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.
[0031] To further understand the invention's content, features, and effects, the following embodiments are provided, and detailed descriptions are given below in conjunction with the accompanying drawings:
[0032] Reference Figure 3 and Figure 4 This invention discloses a lithium-ion battery cell structure, including an aluminum-plastic film 3 for covering electrode sheets and electrolyte, and also including a positive electrode tab 1, a negative electrode tab 2, and an insulating encapsulator 4. The aluminum-plastic film 3 has a rectangular shallow pit surface 31 and a rectangular deep pit surface 32. During the encapsulation of the cell, the bare cell with the positive and negative electrode sheets wound together is placed in the deep pit surface 32 of the aluminum-plastic film 3, and then the aluminum-plastic film 3 is wrapped on the bare cell to form a cell with a rectangular main body. The shallow pit surface 31 and the deep pit surface 32 are respectively located on two opposite surfaces of the cell. The positive electrode tab 1 and the negative electrode tab 2 extend to the same edge of the cell. Both the positive electrode tab 1 and the negative electrode tab 2 are long strip metal sheets and are parallel to each other.
[0033] Reference Figure 3 and Figure 4 The shallow pit surface 31 of the aluminum-plastic film 3 has a liquid replenishment hole 311 that communicates with the inside of the battery cell. The liquid replenishment hole 311 can be a round hole or a polygonal hole. In this embodiment, a round hole is used because the structure of a round hole is more stable, the stress is more even, and it is not easy to break. In this embodiment, the diameter of the liquid replenishment hole 311 is 0.3-0.5mm. The liquid replenishment hole 311 is covered with an insulating encapsulation 4. In this embodiment, the insulating encapsulation 4 is made of adhesive tape. The insulating encapsulation 4 is used to completely seal the liquid replenishment hole 311. The shape of the insulating encapsulation 4 can be circular, rectangular, or... The electrolyte filling hole 311 is elliptical in shape, but rectangular in this embodiment. The filling hole 311 is located near the positive electrode tab 1, meaning the distance between the filling hole 311 and the positive electrode tab 1 is less than the distance between the filling hole 311 and the negative electrode tab 2. The insulating package 4 must meet the sealing pressure test of opening and closing the filling hole 311 for more than 5 times without leakage, so as to avoid leakage of the battery cell during use. The structure of the filling hole 311 and the insulating package 4 can be used to easily open the inside of the battery cell when necessary to replenish the electrolyte inside the battery cell.
[0034] The present invention also discloses a method for using a lithium-ion battery cell structure to maintain the aforementioned lithium-ion battery cell structure, comprising the following steps:
[0035] Step 1: Reduce the voltage of the battery cell. In this embodiment, a discharge process is used to reduce the voltage of the battery cell. Since a voltage below 2.8V will cause certain damage to the battery cell, and a voltage above 3.0V is prone to short circuit and thermal runaway, the voltage of the battery cell is limited to 2.8V-3.0V in this embodiment.
[0036] Step 2: Test the cell structure of the lithium-ion battery described above, and reserve cells that have been cycled more than 1,000 times and / or have a capacity of less than 85%.
[0037] Step 3: Open the insulating package 4 of the battery cell taken in Step 1 in the glove box to expose the liquid replenishment hole 311.
[0038] Step 4: Use a syringe to inject electrolyte a second time through the electrolyte injection hole 311, adding 50-60% of the original standard electrolyte volume of the battery cell. After the electrolyte injection is completed, reseal the electrolyte injection hole 311 with the insulating encapsulation 4.
[0039] Step 5: After sealing the liquid replenishment hole 311, let the battery cell stand at room temperature for more than 12 hours.
[0040] Two identical battery cells were subjected to a cyclic test. Cell 1 was used as a control without undergoing the above steps, while cell 2 underwent a second electrolyte injection and voltage reduction procedure after 1000 cycles. The test results are shown in Table 1. Figure 5 As shown.
[0041] Test results show that the second cell, after secondary electrolyte injection, failed after 1600-1900 cycles instead of the originally designed 1200 cycles (cell capacity less than 80% is considered failure), thus significantly extending cell lifespan. The capacity retention rate test method is as follows: the cell is fully charged and discharged three times, and the discharge amount is recorded. The average of the three discharge amounts is taken to obtain the standard capacity C1 (unit: Ah). Then, a standard charge is performed, followed by storage at a certain temperature (e.g., room temperature) for 28 days. Afterward, a standard discharge is performed to obtain the discharge capacities C2, C3, C4, ..., Cn. The cell capacity retention rate is calculated as Cn / C1 × 100%. The capacity retention rate test method is an existing method and will not be described in detail here.
[0042] Table 1 Comparison of Capacity Retention Rate Data for Normal Cycling Cells and Cells Refilled with Secondary Electrolyte
[0043]
[0044]
[0045]
[0046]
[0047]
[0048]
[0049] The implementation principle and beneficial effects of this invention are as follows: the electrolyte filling hole 311 and the insulating encapsulation 4 cooperate to make the battery cell an internally openable and closable structure. After the battery cell has undergone cycle aging, by opening the insulating encapsulation 4 and injecting electrolyte into the battery cell through the electrolyte filling hole 311 for secondary injection, combined with the operation of reducing the voltage of the battery cell, the problems of lithium ion migration being hindered due to electrolyte loss and the formation of by-products being accelerated by high voltage are solved, thereby increasing the cycle capacity and cycle life of the battery cell. Moreover, this structure and method are low in cost, highly operable, and widely applicable, providing a better method for extending the life of consumer batteries.
[0050] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.
Claims
1. A method for using a lithium-ion battery cell structure for maintaining the lithium-ion battery cell structure, the lithium-ion battery cell structure including a positive electrode tab (1), a negative electrode tab (2), an aluminum-plastic film (3), and an insulating encapsulator (4), wherein the aluminum-plastic film (3) has a shallow pit surface (31) and a deep pit surface (32), a liquid replenishment hole (311) is provided on the shallow pit surface (31), and the insulating encapsulator (4) covers the liquid replenishment hole (311) and completely seals the liquid replenishment hole (311), characterized in that, Includes the following steps: Step 1: Reduce the voltage of the battery cell, limiting it to 2.8V-3.0V; Step 2: Open the insulating encapsulation (4) of the battery cell in the glove box to expose the liquid replenishment hole (311); the insulating encapsulation (4) is adhesive tape; Step 3: Use a syringe to inject electrolyte into the cell a second time through the electrolyte filling hole (311). After the electrolyte filling is completed, reseal the electrolyte filling hole (311).
2. The method of using the lithium-ion battery cell structure according to claim 1, characterized in that, The replenishment hole (311) is a round hole.
3. The method of using the lithium-ion battery cell structure according to claim 1, characterized in that, The distance between the replenishment hole (311) and the positive electrode tab (1) is less than the distance between the replenishment hole (311) and the negative electrode tab (2).
4. The method of using the lithium-ion battery cell structure according to claim 1, characterized in that, The diameter of the replenishment hole (311) is 0.3-0.5 mm.
5. The method of using the cell structure of the lithium-ion battery according to claim 1 or 2, characterized in that, The insulating encapsulation component (4) has a circular, rectangular, or elliptical structure.
6. The method of using the lithium-ion battery cell structure according to claim 1, characterized in that, Take cells that have been cycled more than 1000 times and / or have a capacity of less than 85% and perform steps one through three.
7. The method of using the lithium-ion battery cell structure according to claim 1, characterized in that, A second electrolyte injection should be performed, using 50%-60% of the original standard electrolyte volume for the battery cell.
8. The method of using the lithium-ion battery cell structure according to claim 1, characterized in that, After sealing the liquid replenishment hole (311), the battery cell should be left to stand at room temperature for more than 12 hours before proceeding with the voltage reduction step.