Method of mitigating cell tab creasing and lithium ion battery

Abstract

The application relates to the technical field of lithium ion batteries, and particularly provides a method for slowing down wrinkles of an electrode sheet of a battery cell and a lithium ion battery, aiming to solve the technical problem that the existing mode is too single and cannot effectively improve the wrinkles of the electrode sheet inside the wound battery cell. To this end, the method for slowing down wrinkles of an electrode sheet of the application comprises: performing pretreatment operation on the electrode sheet, the pretreatment operation comprising at least one of water absorption rebound treatment and energy application treatment; winding the pretreated electrode sheet; performing hot pressing on the wound core after winding; assembling, casing and capacity distribution of the hot-pressed wound core. In this way, the full-electricity rebound of the electrode sheet after being made into a battery cell is reduced by pretreating the electrode sheet, thereby reducing the stress release of the electrode sheet inside the battery cell and effectively improving the wrinkles of the electrode sheet inside the battery cell.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, specifically providing a method for mitigating cell electrode wrinkling and a lithium-ion battery. Background Technology

[0002] Aluminum-cased wound cells are currently the main form of energy storage cells. However, compared with other types of cells, wound cells have less internal stress release space and are more prone to electrode wrinkling.

[0003] The existing method improves the wrinkling problem of the battery cell electrode by baking the electrode before winding it. This method is too simplistic and cannot effectively solve the problem that the wrinkles of the electrode inside the wound battery cell mainly occur at the corners and the beginning and end. Summary of the Invention

[0004] To overcome the aforementioned deficiencies, this application is proposed to provide a solution, or at least a partial solution, to the technical problem that existing methods cannot effectively improve cell electrode wrinkling. This application provides a method for mitigating cell electrode wrinkling and a lithium-ion battery.

[0005] In a first aspect, this application provides a method for mitigating cell electrode wrinkling, the method comprising:

[0006] The electrode is pretreated, and the pretreatment includes at least one of water absorption and rebound treatment and energy application treatment;

[0007] The pretreated electrode sheets are wound;

[0008] The wound core is then hot-pressed;

[0009] The hot-pressed core is assembled, placed into the shell, and fully charged.

[0010] In one embodiment of this application, the pre-processing operation of the negative electrode sheet includes: performing a pre-processing operation on the negative electrode sheet after performing rolling, slitting or die-cutting operations.

[0011] In one embodiment of this application, the energy application process includes flame treatment of the electrode;

[0012] The pretreatment operation for the electrode includes:

[0013] The negative electrode sheet is subjected to water absorption and rebound treatment;

[0014] After the negative electrode sheet undergoes water absorption and rebound treatment, it is left to stand for a first preset time before being subjected to flame treatment.

[0015] In one embodiment of this application, the water absorption and rebound treatment of the negative electrode sheet includes: placing the negative electrode sheet in a semi-enclosed space and performing a rewinding operation at a preset speed.

[0016] In one embodiment of this application, the humidity of the semi-enclosed space is 75% to 95%, the temperature of the semi-enclosed space is 20°C to 30°C, and the preset speed is 0 to 30 m / min.

[0017] In one embodiment of this application, the first preset duration is 2h to 48h.

[0018] In one embodiment of this application, when the negative electrode sheet is flame-treated, the flame temperature is 200℃~800℃ and the belt speed is 0~50m / min.

[0019] In one embodiment of this application, the winding of the pre-treated electrode sheet includes: winding the electrode sheet with a preset tension, wherein the fluctuation amplitude of the preset tension is less than or equal to a preset amplitude threshold.

[0020] In one embodiment of this application, the hot pressing time is greater than or equal to a second preset time.

[0021] In a second aspect, a lithium-ion battery is provided, which is manufactured using the aforementioned method for reducing cell electrode wrinkling.

[0022] The above-described technical solutions of this application have at least one or more of the following features. Beneficial effects:

[0023] The method for mitigating cell electrode wrinkling in this application includes: pre-treating the electrode, the pre-treatment including at least one of water absorption rebound treatment and energy application treatment; winding the pre-treated electrode; hot-pressing the wound core; assembling, casing, and fully charging the hot-pressed core. Thus, by pre-treating the electrode, the full-charge rebound after the electrode is manufactured into a cell is reduced, thereby reducing stress release of the electrode inside the cell, effectively improving the wrinkling phenomenon of the electrode inside the cell, and increasing user satisfaction. Attached Figure Description

[0024] The disclosure of this application will become more readily understood with reference to the accompanying drawings. It will be readily understood by those skilled in the art that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this application. Furthermore, similar numbers in the drawings are used to denote similar components, wherein:

[0025] Figure 1 This is a schematic diagram of the main process of a method for reducing cell electrode wrinkling in one embodiment of this application;

[0026] Figure 2 This is a complete flowchart illustrating a method for mitigating cell electrode wrinkling in one embodiment of this application;

[0027] Figure 3 This is a schematic diagram of the rebound ratio of the electrode after performing pre-rebound treatment in one embodiment of this application;

[0028] Figure 4 This is a schematic diagram of the rebound ratio of a battery cell after being fully charged in one embodiment of this application. Detailed Implementation

[0029] Some embodiments of this application are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of this application and are not intended to limit the scope of protection of this application.

[0030] In the description of this application, "module" and "processor" can include hardware, software, or a combination of both. A module can include hardware circuitry, various suitable sensors, communication ports, memory, and can also include software components, such as program code, or a combination of software and hardware. A processor can be a central processing unit, microprocessor, image processor, digital signal processor, or any other suitable processor. The processor has data and / or signal processing capabilities. The processor can be implemented in software, in hardware, or a combination of both. Non-transitory computer-readable storage media includes any suitable medium capable of storing program code, such as magnetic disks, hard disks, optical disks, flash memory, read-only memory, random access memory, etc. The term "A and / or B" means all possible combinations of A and B, such as only A, only B, or A and B. The terms "at least one A or B" or "at least one of A and B" have a similar meaning to "A and / or B" and can include only A, only B, or A and B. The singular terms "a" or "this" can also include plural forms.

[0031] The current traditional method is to bake the electrode sheets before winding them to improve the wrinkling problem of the battery cell electrode sheets. This method is too simple and cannot effectively improve the situation where the wrinkles of the electrode sheets inside the wound battery cell mainly occur at the corners and the beginning and end.

[0032] Therefore, this application proposes a method for mitigating cell electrode wrinkling and a lithium-ion battery.

[0033] See appendix Figure 1 , Figure 1 This is a schematic flowchart of the main steps of a method for mitigating cell electrode wrinkling according to an embodiment of this application.

[0034] like Figure 1As shown, the method for mitigating cell electrode wrinkling in this embodiment mainly includes the following steps S10-S40.

[0035] Step S10: Perform a pretreatment operation on the electrode, which includes at least one of water absorption rebound treatment and energy application treatment.

[0036] The water-rebound treatment primarily utilizes moisture to cause slight expansion of the electrode material, followed by natural shrinkage during the drying process, thereby releasing internal stress. This treatment helps reduce the likelihood of wrinkles forming on the electrode during subsequent processing (such as winding).

[0037] Applying energy treatment mainly involves using specific forms of energy (such as thermal, mechanical, or electromagnetic energy) to alter the physical properties of the electrode surface, increasing its flexibility and compliance. Energy treatment can include flame treatment, corona treatment, plasma treatment, infrared treatment, and uncoiling baking treatment.

[0038] Flame treatment is a method that involves briefly exposing the electrode surface to a high-temperature flame, using high-energy particles (such as oxygen, nitrogen, and other reactive species) in the flame to bombard the electrode surface, thereby altering the chemical structure and physical properties of the electrode surface.

[0039] Corona treatment uses a high-voltage power supply to generate corona discharge, creating a high-energy plasma environment on the electrode surface.

[0040] Plasma treatment utilizes low-temperature plasma generated by gas discharge to bombard the surface of the electrode.

[0041] Infrared processing uses infrared radiation electrodes.

[0042] Uncoil baking is a process in which the electrode sheets are unrolled from the roll and placed in an oven for heating.

[0043] Step S20: Wind the pretreated electrode sheet.

[0044] Step S30: Hot-press the wound core.

[0045] Step S40: Assemble the hot-pressed core, insert it into the shell, and fully charge it.

[0046] Based on steps S10-S40 above, the electrode sheets are first pre-treated, including at least one of water absorption rebound treatment and energy application treatment; the pre-treated electrode sheets are then wound; the wound core is hot-pressed; and the hot-pressed core is assembled, placed into the casing, and fully charged. In this way, by pre-treating the electrode sheets, the full-charge rebound after the electrode sheets are manufactured into the battery cell is reduced, thereby reducing stress release of the electrode sheets inside the battery cell, effectively improving the wrinkling phenomenon of the electrode sheets inside the battery cell, and increasing user satisfaction.

[0047] The following provides further explanation of steps S10 to S40.

[0048] Regarding step S10 above, in one specific embodiment of the electrode pretreatment operation, the electrode pretreatment operation includes: performing a pretreatment operation on the negative electrode after performing rolling, slitting or die-cutting operations.

[0049] Roll forming refers to the process in lithium battery production where positive and negative electrode materials are first coated onto a current collector to form electrode sheets, and then the thickness and density of the electrode sheets are adjusted through a roll forming process to achieve the desired electrochemical performance.

[0050] Slitting refers to the process of cutting large-area electrode sheets into smaller-sized electrode sheets suitable for specific battery models in order to meet the design requirements of batteries of different sizes and shapes.

[0051] Die cutting refers to the process of using a mold to directly punch out the required electrode shape from a large electrode sheet for batteries with certain special shape or size requirements.

[0052] Pre-treating negative electrode sheets after rolling, slitting, or die-cutting can effectively prevent electrode wrinkling. By selecting appropriate pre-treatment methods, the quality of the electrode sheets can be significantly improved, thereby enhancing the performance and reliability of the entire battery product.

[0053] The following details the specific methods used in this application for preprocessing the electrode sheets.

[0054] In one specific manner of pre-treating the electrode sheet, the energy application treatment includes flame treatment of the electrode sheet; the pre-treating operation of the electrode sheet includes: performing water absorption and rebound treatment on the negative electrode sheet; after the negative electrode sheet after water absorption and rebound treatment has been left to stand for a first preset time, the negative electrode sheet is then flame treated.

[0055] Specifically, the pretreatment operation for the electrode sheet can be to first perform water absorption and rebound treatment on the negative electrode sheet, then let the negative electrode sheet stand for a first preset time after the water absorption and rebound treatment, and then perform flame treatment on the negative electrode sheet.

[0056] Specifically, simply increasing the humidity of the negative electrode storage environment is sufficient to complete the pre-rebound of the electrode. This achieves the water absorption rebound treatment of the negative electrode without adding any extra procedures or costs, and can effectively release the stress accumulated inside the negative electrode.

[0057] In one specific embodiment of the water absorption and rebound treatment of the negative electrode sheet, the water absorption and rebound treatment of the negative electrode sheet includes: placing the negative electrode sheet in a semi-enclosed space and performing a rewinding operation at a preset speed.

[0058] Rewinding refers to rewinding the processed negative electrode material to facilitate storage under specified environmental conditions.

[0059] Specifically, the water absorption and rebound treatment of the negative electrode sheet is to place the negative electrode sheet in a semi-enclosed space and wind it at a preset speed. At this time, the negative electrode sheet can absorb a certain amount of water, thus achieving the effect of water absorption and rebound.

[0060] In one specific embodiment of this application, the humidity of the semi-enclosed space is 75% to 95%, the temperature of the semi-enclosed space is 20°C to 30°C, and the preset speed is 0 to 30 m / min.

[0061] Specifically, the negative electrode sheet can be placed in a semi-enclosed space with a humidity of 75% to 95% and a temperature of 20°C to 30°C, and then reverse-winded at any speed of 0 to 30 m / min. This achieves the effect of pre-rebounding water absorption on the negative electrode sheet, which helps to reduce the stress on the electrode sheet during the subsequent winding process, especially in areas where stress is concentrated, such as corners and the beginning and end ends.

[0062] In one embodiment, the negative electrode sheet after water absorption and rebound treatment is left to stand for a first preset time, which can be 2h to 48h.

[0063] For example, 6h, 10h, 24h, etc. can be used as examples of the first preset duration.

[0064] In one specific embodiment of flame treatment of the negative electrode sheet, the flame temperature is 200℃~800℃ and the belt speed is 0~50m / min.

[0065] Specifically, the negative electrode sheet can be placed on the conveyor belt of the conveyor system, and the conveyor belt can be controlled to travel at any speed between 0 and 50 m / min. This exposes the negative electrode sheet to a high-temperature flame of 200℃ to 800℃, using high-energy particles in the flame to bombard the surface of the negative electrode sheet, thereby changing its surface properties. This achieves a pre-rebound effect on the negative electrode sheet, which helps reduce stress on the electrode sheet during subsequent winding, especially in areas of stress concentration such as corners and the beginning and end points.

[0066] The above is a further explanation of step S10. Step S20 will be further explained below.

[0067] Specifically, the positive and negative electrodes and the separator can be tightly wound together in a specific order to form a complete core. During the winding process, the electrodes and separator are wound together according to a preset order and speed to form the battery cell. In this process, it is necessary to ensure that each layer of electrodes and separator fits tightly while maintaining an appropriate gap to ensure the performance and stability of the battery cell. Because pretreatment reduces the internal stress of the electrodes, tension control during the winding process becomes easier, further reducing the risk of electrode wrinkling. Pretreated electrodes are more flexible and have a more uniform stress distribution, making them less prone to wrinkling during winding and ensuring the consistency and compactness of the core structure.

[0068] In one specific embodiment of winding the pre-treated electrode sheet, winding the pre-rebounded electrode sheet includes: winding the electrode sheet with a preset tension, wherein the fluctuation amplitude of the preset tension is less than or equal to a preset amplitude threshold.

[0069] The preset amplitude threshold can be determined in advance based on experiments, and can be adjusted adaptively according to the actual use scenario.

[0070] For example, appropriate values ​​for the tension of the positive electrode, negative electrode, positive electrode separator, and negative electrode separator can be selected to test the electrode tension and separator tension of the lithium battery, thereby obtaining the fluctuation range of the electrode tension. The appropriate values ​​for the tension of the positive electrode, negative electrode, positive electrode separator, and negative electrode separator are selected based on the lowest winding tension of the electrode and separator during the winding process, that is, to avoid poor coating or misalignment under low tension. The values ​​are selected by verifying that the maximum tension will cause the core to be too tight, resulting in rebound deformation.

[0071] The above is a further explanation of step S20. Step S30 will be further explained below.

[0072] Specifically, step S30 involves placing the core in a mold at a controlled temperature for compression, allowing the electrode and separator to adhere more tightly together, thus enhancing the overall mechanical strength and electrochemical performance. Hot-pressing the core helps eliminate any tiny gaps or uneven areas that may remain after winding, ensuring a tight bond between the layers.

[0073] The hot-pressing temperature of the battery cell can be any temperature between 80℃ and 90℃. This temperature range ensures optimal bonding through hot pressing without damaging the chemical and physical properties of the internal materials (such as the positive and negative electrodes, separator, and electrolyte). Simultaneously, an appropriate hot-pressing temperature promotes intermolecular interactions between materials, improving the cell's conductivity and structural strength.

[0074] In one specific embodiment of this application, the hot pressing of the wound core is performed, and the hot pressing time is greater than or equal to a second preset time.

[0075] The second preset duration can be a time obtained through experiments, and can be adjusted adaptively according to the actual scenario. For example, 50s, 55s, 60s, etc. can be used as examples of the second preset duration.

[0076] For example, the hot-pressing time can be any time between 60 seconds and 90 seconds. This time range is chosen to ensure that the cell has enough time to adapt to temperature changes during the hot-pressing process and to achieve full bonding between the materials. In this way, sufficient hot-pressing time can ensure good contact between the electrodes and the separator inside the cell, thereby improving the cycle performance and safety of the cell.

[0077] The hot pressing pressure can range from 4000 kgf / cm². 2 ~6000 kgf / cm 2 (kgf / cm²), this pressure range is chosen to generate sufficient pressure inside the cell to promote a tight bond between the electrodes and the separator. Appropriate hot-pressing pressure ensures that the materials inside the cell do not shift or deform during the hot-pressing process, while also helping to improve the cell's compaction density and energy density.

[0078] By employing the hot-pressing step in the battery cell manufacturing process, including appropriate hot-pressing temperature, time, and pressure—three key parameters—the aim is to ensure that the battery cell achieves optimal physical and chemical properties during the hot-pressing process, thereby improving the overall quality and reliability of the battery cell.

[0079] The above is a further explanation of step S30. Step S40 will be further explained below.

[0080] Specifically, in step S40 above, the hot-pressed core can first be assembled and placed into the casing. This involves assembling the hot-pressed cell with other necessary components (such as tabs) to form a complete battery cell. During assembly, ensure the correct polarity and position of the cell to avoid short circuits and performance degradation. The assembled cell is then placed into the battery casing, which typically protects the cell from external environmental influences. Appropriate fixing methods (such as screws or welding) are used to secure the cell within the casing, ensuring it does not move or get damaged during charging and discharging.

[0081] After the hot-pressed core is assembled and placed into the casing, the assembled battery cell is sequentially subjected to liquid injection, stabilization, formation, and capacity testing processes.

[0082] Electrolyte injection involves adding an appropriate amount of electrolyte into the battery casing. The electrolyte is the medium for ion transport within the battery and has a significant impact on battery performance. During the injection process, it is necessary to control the amount and injection rate of electrolyte to avoid degrading battery performance due to excessive or insufficient electrolyte.

[0083] After electrolyte filling is completed, allow the battery to stand at room temperature for a period of time to allow the electrolyte to fully wet the materials inside the cell. The length of the standing time depends on the specifications of the cell and the type of electrolyte, and usually ranges from several hours to tens of hours.

[0084] The process of charging and discharging a battery with a small current is called formation. During formation, a series of chemical reactions occur inside the battery, forming a stable electrochemical interface. The purpose of formation is to activate the active materials inside the battery, improving its performance and stability. It is necessary to control the charging and discharging current and voltage during formation to avoid overcharging or over-discharging, which could damage the battery.

[0085] After formation, the batteries undergo capacity testing, a process known as capacity grading. During capacity grading, parameters such as capacity and internal resistance are measured to evaluate the battery's performance and quality. Based on the grading results, the batteries are classified into different grades or batches for subsequent use and management.

[0086] The sequential processes of electrolyte injection, stabilization, formation, and capacity testing for battery cells not only improve their safety and reliability but also ensure that the battery meets its expected performance specifications. Ultimately, these processed cells can be assembled into battery packs for use in various electronic devices and energy storage systems.

[0087] Specifically, the battery cells prepared according to the aforementioned method can also be disassembled. By disassembling the battery cells, the condition of the internal electrodes can be observed directly, including the flatness of the electrodes, the presence or absence of wrinkles, and the amount of wrinkles.

[0088] After disassembling the battery cell, check the wrinkles on the electrode interface. If wrinkles are present on the electrode interface, the pre-rebound operation in the pre-processing step can be further adjusted to optimize the flatness of the battery cell electrode, reduce the generation of wrinkles, and thus improve the performance and reliability of the battery cell.

[0089] According to the above scheme, the electrode wrinkling of lithium-ion batteries after full capacity testing can be significantly improved, preventing the occurrence of battery wrinkling and capacity decay.

[0090] Figure 2 This can be a complete flowchart of a method for improving cell electrode wrinkles in one embodiment of this application.

[0091] Specifically, such as Figure 2 As shown, the method to improve the wrinkles of the battery cell electrode sheets can be achieved through the following steps S1-S6.

[0092] Step S1: Perform water absorption and rebound treatment on the negative electrode.

[0093] For example, the negative electrode sheet after rolling, slitting or die-cutting can be placed in a semi-enclosed space with a humidity of ≥80% and a temperature of 20℃~30℃, and then rolled back at any speed of 0~30m / min.

[0094] Step S2: Let the negative electrode plate stand for the first preset time.

[0095] For example, after the negative electrode sheet undergoes water absorption and rebound, it can be left to stand for 2 hours to 48 hours.

[0096] Step S3: Flame treatment of the negative electrode.

[0097] For example, the negative electrode can be placed on the conveyor belt of the conveyor system, and the conveyor belt can be controlled to travel at any speed from 0 to 50 m / min, so that the negative electrode is exposed to a high-temperature flame of 200°C to 800°C, and the surface of the negative electrode is bombarded by high-energy particles in the flame to change the surface characteristics of the negative electrode.

[0098] Step S4: Wind the positive electrode, negative electrode and separator.

[0099] Specifically, this can be achieved by winding the pre-rebounded positive electrode, negative electrode, and separator with a preset tension.

[0100] Step S5: Hot press the wound core.

[0101] Specifically, the wound core can be hot-pressed according to preset hot-pressing pressure, hot-pressing time, and hot-pressing temperature to ensure that the cell has enough time to adapt to temperature changes during the hot-pressing process and to achieve full bonding between materials. In this way, sufficient hot-pressing time can ensure good contact between the electrodes and separator inside the cell, thereby improving the cycle performance and safety of the cell.

[0102] Step S6: Assemble the hot-pressed core, insert it into the shell, and fully charge it.

[0103] Specifically, the hot-pressed battery cells can be assembled with other necessary components (such as tabs) to form a complete battery cell. The assembled battery cells are then placed into the battery casing and secured inside the casing using appropriate fixing methods (such as screws, welding, etc.) to ensure that the battery cells do not move or get damaged during charging and discharging. The assembled battery cells are then subjected to electrolyte injection, resting, formation, and full-charge testing processes in sequence.

[0104] By performing a pre-rebound operation on the electrode sheets, the full-charge rebound after the electrode sheets are made into a battery cell is reduced, thereby reducing the stress release of the electrode sheets inside the battery cell and improving the wrinkling phenomenon of the electrode sheets inside the battery cell, especially in areas with stress concentration such as corners and the beginning and end ends.

[0105] Specifically, compared to the pre-rebound process of baking for electrode sheets, the pre-rebound process of water absorption for negative electrodes only requires appropriately increasing the humidity of the storage environment, without adding extra steps or costs. Compared to baking for electrode sheets, applying energy (e.g., flame treatment) to the negative electrode results in higher pre-rebound efficiency and a more controllable degree of pre-rebound. Higher pre-rebound efficiency leads to lower rebound efficiency in fully charged cells, resulting in a more significant improvement in the wrinkling problem of the negative electrode sheet. Furthermore, the thicker the electrode sheet, the more significant the improvement in electrode wrinkling using the aforementioned methods.

[0106] In existing technologies, conventional positive and negative electrode sheets are sequentially wound and hot-pressed, and the hot-pressed core is then assembled, placed into a casing, and fully charged to obtain the battery cell.

[0107] The method for improving cell electrode wrinkles according to this application will now be described in detail with reference to embodiments. Example 1

[0108] First, the rolled negative electrode sheet undergoes a pre-rebound treatment. Specifically, the rolled negative electrode sheet is placed in a semi-enclosed space with a humidity of 80±5% and a temperature of 25±5℃, and is rewound at a speed of 5m / min. Then, it is left to stand in a conventional production space for 6 hours, followed by a flame rebound treatment. The flame temperature can be 500℃, and the belt speed is 10m / min. This process yields a pre-rebound treated negative electrode sheet.

[0109] Next, the conventional positive electrode, the pre-rebound negative electrode, and the separator are wound together to obtain a wound core. The wound core is then hot-pressed. Finally, the hot-pressed core is assembled, packaged, and fully charged to obtain a fully charged battery cell. Example 2

[0110] First, the rolled negative electrode sheet undergoes a pre-rebound treatment. Specifically, the rolled negative electrode sheet is placed in a semi-enclosed space with a humidity of 90±5% and a temperature of 25±5℃, and is rewound at a speed of 10m / min. Then, it is left to stand in a conventional production space for 24 hours, followed by a flame rebound treatment. The flame temperature can be 600℃, and the conveyor belt speed is 5m / min. This process yields a pre-rebound treated negative electrode sheet.

[0111] Next, the conventional positive electrode, the pre-rebound negative electrode, and the separator are wound together to obtain a wound core. The wound core is then hot-pressed. Finally, the hot-pressed core is assembled, packaged, and fully charged to obtain a fully charged battery cell.

[0112] For example, Figure 3 This is a schematic diagram showing the rebound ratio of the negative electrode after pre-rebound treatment, where the horizontal axis represents the example number and the vertical axis represents the rebound ratio of the electrode. Figure 3 It can be seen that the rebound rate of the negative electrode corresponding to Example 1 is higher than that of the negative electrode corresponding to Example 2.

[0113] For example, Figure 4 It is an existing method (i.e.) Figure 4 Comparative Example 1) and Example 2: Schematic diagram of the rebound ratio of the battery cells after full charge and capacity testing, where the horizontal axis represents the example number and the vertical axis represents the rebound ratio of the electrode. Figure 4 It can be seen that, for the final obtained battery cell, the electrode sheet obtained in the first embodiment above has the lowest rebound rate, resulting in the fewest corresponding battery cell wrinkles; while the battery cell obtained by the existing method has the highest rebound rate, resulting in the most corresponding battery cell wrinkles. Therefore, the method of this application can effectively improve the electrode sheet wrinkles of the battery cell.

[0114] It should be noted that although the steps in the above embodiments are described in a specific order, those skilled in the art will understand that, in order to achieve the effect of this application, different steps do not necessarily have to be executed in such an order. They can be executed simultaneously (in parallel) or in other orders, and these variations are all within the scope of protection of this application.

[0115] Furthermore, this application also provides a lithium-ion battery, which is manufactured using the method for improving cell electrode wrinkles described in the foregoing embodiments.

[0116] The technical solution of this application has been described in conjunction with the specific embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of this application is obviously not limited to these specific embodiments. Without departing from the principles of this application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of this application.

Claims

1. A method for mitigating wrinkles on battery cell electrode sheets, characterized in that, The method includes: The electrode is pretreated, and the pretreatment includes at least one of water absorption and rebound treatment and energy application treatment; The pretreated electrode sheets are wound; The wound core is then hot-pressed; The hot-pressed core is assembled, placed into the shell, and fully charged.

2. The method for mitigating cell electrode wrinkling according to claim 1, characterized in that, The pre-processing operation of the negative electrode sheet includes: pre-processing the negative electrode sheet after performing rolling, slitting or die-cutting operations.

3. The method for mitigating cell electrode wrinkling according to claim 2, characterized in that, The energy application process includes flame treatment of the electrode; The pretreatment operation for the electrode includes: The negative electrode sheet is subjected to water absorption and rebound treatment; After the negative electrode sheet undergoes water absorption and rebound treatment, it is left to stand for a first preset time before being subjected to flame treatment.

4. The method for mitigating cell electrode wrinkling according to claim 3, characterized in that, The water absorption and rebound treatment of the negative electrode sheet includes: placing the negative electrode sheet in a semi-enclosed space and performing a rewinding operation at a preset speed.

5. The method for mitigating cell electrode wrinkling according to claim 4, characterized in that, The humidity of the semi-enclosed space is 75% to 95%, the temperature of the semi-enclosed space is 20°C to 30°C, and the preset speed is 0 to 30 m / min.

6. The method for mitigating cell electrode wrinkling according to claim 3, characterized in that, The first preset duration is 2h to 48h.

7. The method for mitigating cell electrode wrinkling according to claim 3, characterized in that, When the negative electrode is flame-treated, the flame temperature is 200℃~800℃ and the belt speed is 0~50m / min.

8. The method for mitigating cell electrode wrinkling according to claim 1, characterized in that, The winding of the pre-treated electrode sheet includes: winding the electrode sheet with a preset tension, wherein the fluctuation amplitude of the preset tension is less than or equal to a preset amplitude threshold.

9. The method for mitigating cell electrode wrinkling according to claim 1, characterized in that, The hot pressing time is greater than or equal to the second preset time.

10. A lithium-ion battery, said lithium-ion battery being manufactured using the method for mitigating cell electrode wrinkling as described in any one of claims 1-9.

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