Method for improving alignment of tabs of a wound battery

Abstract

The application belongs to the technical field of battery manufacturing, and discloses a method for improving the alignment of tabs of a winding battery. The method comprises the following steps: when a winding change instruction of a winding device is triggered, recording a first conveying length value L1 of raw materials after a single winding roller rotates by a preset angle Φ; after the raw material roll is replaced, recording a second conveying length value L2 of the raw materials after the single winding roller rotates by the preset angle Φ; when the absolute value of the length difference ΔL between the first conveying length value L1 and the second conveying length value L2 exceeds a preset difference ΔL0, it is determined that the tabs are deviated; and the thickness of the pole piece is adjusted according to the length difference ΔL. The method can find the tab misalignment information in time during the winding change process, and automatically adjust the alignment of the tabs according to the misalignment information, so that the adjustment accuracy is improved and the waste rate is reduced.

Description

Technical Field

[0001] This invention relates to the field of battery manufacturing technology, and in particular to a method for improving the alignment of tabs in a wound battery. Background Technology

[0002] During the winding process of wound batteries, the alignment of the tabs is greatly affected by the thickness of the incoming material. The fluctuation of the electrode thickness is mainly manifested in the replacement of the electrode roll and the separator (reduction in the speed of the roller pressing when changing the roll, batch changes of the separator, and the thinning of the separator due to the high tension of the inner ring and the pressure of the inner ring). The current industry practice is to adjust the Teflon on the winding needle or change the winding needle diameter based on the tab misalignment information of the first cell after the roll is changed. This often inevitably results in the scrapping of at least one cell to confirm the misalignment before various remedial measures are taken for the next cell. This strategy often has a lag problem. Once the electrode thickness (separator thickness) fluctuates greatly before and after the roll is changed, poor tab alignment and scrapping are often unavoidable. The more times the roll is changed, the more scraps are generated.

[0003] Therefore, there is an urgent need to propose a method that can promptly detect tab misalignment information during roll changing and automatically adjust the tab alignment based on the misalignment information. Summary of the Invention

[0004] The purpose of this invention is to provide a method for improving the alignment of tabs in wound batteries. The method provided by this invention can detect tab misalignment information in a timely manner during the winding process and automatically adjust the tab alignment according to the misalignment information, thereby improving the adjustment accuracy and reducing the scrap rate.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] This invention discloses a method for improving the alignment of tabs in a wound battery, comprising the following steps:

[0007] When the winding device’s roll change command is triggered, the first conveying length value L1 of the output material is recorded after the single roll needle rotates a preset angle Φ.

[0008] After changing the raw material roll, after the single roll needle rotates by the preset angle Φ, record the second conveying length value L2 of the output raw material after the roll change;

[0009] When the absolute value of the length difference ΔL between the first conveying length value L1 and the second conveying length value L2 exceeds the preset difference ΔL0, it is determined that the tab has deviated.

[0010] The thickness of the electrode is adjusted according to the length difference ΔL.

[0011] The beneficial effects of the method for improving the alignment of tabs in a wound battery according to the present invention are as follows: During the execution of the roll change command, the first conveying length value L1 of the output material is recorded after the single roll needle rotates by a preset angle Φ. After the material roll is changed, the second conveying length value L2 of the output material is recorded after the single roll needle rotates by a preset angle Φ. The length difference ΔL between the first conveying length value L1 and the second conveying length value L2 can clearly characterize the thickness difference of the output material before and after the roll change. If the absolute value of the length difference ΔL exceeds the preset difference ΔL0, it can be determined that the tabs will definitely be misaligned during the subsequent winding process. At this time, the thickness of the electrode sheet can be adjusted according to the length difference ΔL to correct the offset of the tabs in time. This achieves the purpose of timely detection of tab misalignment information during the roll change process and automatic adjustment of tab alignment according to the misalignment information, thereby improving the accuracy of tab correction and reducing the scrap rate.

[0012] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the winding device;

[0014] Figure 2 This is a flowchart illustrating the method for improving the alignment of tabs in a wound battery according to Embodiment 1 of the present invention.

[0015] Figure label:

[0016] 100. Cell winding needle; 200. Positive electrode sheet; 300. Negative electrode sheet; 400. Upper separator; 500. Lower separator; 600. Single-winding needle; 700. Electrode sheet shaping roller; Detailed Implementation

[0017] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0018] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0019] In the description of this embodiment, the terms "upper," "lower," "left," "right," "front," and "rear," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0020] This invention discloses a method for improving the alignment of tabs in a wound battery (hereinafter referred to as the method provided by this invention for ease of description), refer to Figure 2 As shown, the method provided by this invention includes the following steps:

[0021] S1: When the winding device’s roll change command is triggered, the single roll needle rotates 600 degrees at a preset angle Φ and the first conveying length value L1 of the output material is recorded.

[0022] S2: After changing the raw material roll, after the single roll needle rotates 600 degrees to a preset angle Φ, record the second conveying length value L2 of the output raw material after the roll change;

[0023] S3: When the absolute value of the length difference ΔL between the first conveying length value L1 and the second conveying length value L2 exceeds the preset difference ΔL0, it is determined that the electrode tab has deviated.

[0024] S4: Adjust the thickness of the electrode sheet according to the length difference ΔL.

[0025] It should be noted that the reference Figure 1 As shown, during the cell winding process, a single-winding action occurs whenever either the electrode roll (including the positive electrode 200 and the negative electrode 300) or the separator roll (including the upper separator 400 and the lower separator 500) needs to be changed. This action is used to locate the starting point of the EA (Electrical Acid) or the position of the separator adhesive tape. The single-winding process involves the single-winding needle 600 rotating to wind up the remaining portion of the old material roll when the winding equipment's change-of-roll command is triggered. After the change-of-roll is completed, a portion of the new material roll is wound up, and then the cell winding needle 100 continues winding to manufacture the cell. If the thickness of the output material remains constant, the tabs on the wound cell should be aligned correctly before and after the change-of-roll, without any deviation. However, due to manufacturing reasons, thickness deviations may occur between the new and old material rolls. In this case, tab misalignment will occur before and after the change-of-roll.

[0026] It is understood that the method disclosed in this embodiment, during the roll change command execution process, first measures the rotation of the single roll needle 600 by a preset angle Φ and records the first conveying length value L1 of the output material. After measuring the change of the material roll, after the single roll needle 600 rotates by a preset angle Φ, records the second conveying length value L2 of the output material after the roll change. The length difference ΔL between the first conveying length value L1 and the second conveying length value L2 can clearly characterize the thickness difference of the output material before and after the roll change. If the absolute value of the length difference ΔL exceeds the preset difference ΔL0, it can be determined that the tab will definitely be misaligned during the subsequent winding process. At this time, adjusting the thickness of the electrode sheet according to the length difference ΔL can correct the offset of the tab in time. This achieves the purpose of timely detection of tab misalignment information during the roll change process and automatic adjustment of the tab alignment according to the misalignment information, thereby improving the accuracy of tab error correction and reducing the scrap rate.

[0027] It should be further explained that the first conveying length value L1 and the second conveying length value L2 can be measured by a length-measuring roller installed on the conveying path of the output raw material in the winding equipment, or by installing a detector on the single-roll winding needle 600 and measuring the increase in diameter of the material wound on the single-roll winding needle 600 and converting it into the first conveying length value L1 and the second conveying length value L2. Of course, in the implementation of the method provided by the present invention, the first conveying length value L1 and the second conveying length value L2 can also be measured according to actual needs, and are not limited to the above description.

[0028] Optionally, the preset difference ΔL0 ranges from 1mm to 5mm, and the preset difference ΔL0 can be 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, 3mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm, 3.6mm, 3.7mm, 3.8mm, 3.9mm, 4mm, 4.1mm, 4.2mm, 4.3mm, 4.4mm, 4.5mm, 4.6mm, 4.7mm, 4.8mm, 4.9mm, or 5mm. Of course, the preset difference ΔL0 can also be selected from other values ​​within 1mm-5mm according to actual needs, and is not limited to the examples mentioned above. In the implementation of the method provided by this invention, the preset difference ΔL0 needs to be determined according to the actual requirements of cell winding.

[0029] Optionally, the length difference ΔL and the electrode thickness compensation value h satisfy the following relationship: h = ((ΔL / (Φ / 360)) / 6.28) × Q. Q is a compensation constant, ranging from 0.01 to 5. The compensation constant is set based on practical experience and electrode winding process requirements. In other embodiments of the present invention, the relationship between the length difference ΔL and the electrode thickness compensation value h can be modified according to actual needs. The above formula only provides one method for calculating the electrode thickness.

[0030] Optionally, the preset angle Φ can be in the range of 1080°-5400°. Specifically, the preset angle Φ can be 1080°, 1440°, 1800°, 2160°, 2520°, 2880°, 3240°, 3600°, 3960°, 4320°, 4680°, 5040°, or 5400°. Of course, the preset angle Φ can also be other values ​​within the above range, and is not limited to the examples listed above. It is understood that if the preset angle Φ is too large, it will prolong the time required to detect the first conveying length value L1 and the second conveying length value L2 during the process provided by this invention, thereby affecting the manufacturing efficiency of the battery cell. Furthermore, since the larger the angle through which a single winding needle rotates 600 revolutions, the larger the length difference ΔL between the first conveying length value L1 and the second conveying length value L2, setting the preset angle Φ too large may increase the probability of misjudgment. If the preset angle Φ is too small, although it will shorten the time required to detect the first conveying length value L1 and the second conveying length value L2, the smaller the angle through which a single winding needle rotates 600 degrees, the smaller the length difference ΔL between the first conveying length value L1 and the second conveying length value L2 will be, which will also increase the probability of misjudgment. In this embodiment, the preset angle Φ is set to 1080°-5400°, which can control the time required to detect the first conveying length value L1 and the second conveying length value L2, ensuring the manufacturing efficiency of the battery cell, while also reducing the probability of misjudgment and improving the adjustment accuracy.

[0031] It should be noted that in other embodiments of the present invention, the preset angle Φ can be selected according to actual needs and is not limited to the above limitations. For ease of data recording, the preset angle Φ is preferably an integer multiple of 360°.

[0032] Optionally, the output raw materials include at least one of the following: positive electrode sheet 200, negative electrode sheet 300, upper separator 400, or lower separator 500. It is understood that during the actual winding process, excessive thickness deviations in the positive electrode sheet 200, negative electrode sheet 300, upper separator 400, or lower separator 500 before and after rewinding can cause tab misalignment. In the actual implementation of the method provided by this invention, at least one of the following can be used to measure the first conveying length value L1 and the second conveying length value L2, thereby improving the tab correction accuracy and reducing the scrap rate.

[0033] It should be further noted that, in the implementation of the method provided by this invention, if the measured values ​​are the first conveying length L1 and the second conveying length L2 of the positive electrode 200 before and after rewinding, then the thickness of the positive electrode 200 needs to be adjusted when adjusting the electrode thickness; if the measured values ​​are the first conveying length L1 and the second conveying length L2 of the negative electrode 300 before and after rewinding, then the thickness of the negative electrode 300 needs to be adjusted when adjusting the electrode thickness; if the measured values ​​are the first conveying length L1 and the second conveying length L2 of the lower diaphragm 500 or the upper diaphragm 400 before and after rewinding, then the thickness of the positive electrode 200 or the negative electrode 300 needs to be adjusted when adjusting the electrode thickness.

[0034] Optionally, when the output material is a positive electrode 200 and / or a negative electrode 300, the length difference ΔL and the electrode thickness compensation value h satisfy the following relationship: h = ((ΔL / (Φ / 360)) / 6.28) × 3. When the length difference ΔL and the electrode thickness compensation value h satisfy the embodiment of this example, accurate compensation for the electrode misalignment can be guaranteed, thereby improving the electrode alignment of the adjusted cell.

[0035] Optionally, when the output material is an upper diaphragm 400 and / or a lower diaphragm 500, the length difference ΔL and the electrode thickness compensation value h satisfy the following relationship: h = ((ΔL / (Φ / 360)) / 6.28) × 0.035. When the length difference ΔL and the electrode thickness compensation value h satisfy the requirements of this embodiment, accurate compensation for the electrode misalignment can be guaranteed, thereby improving the electrode alignment of the adjusted cell.

[0036] Optionally, when the remaining length L3 of the output material is less than the preset length value L0, a roll-changing command is triggered on the winding equipment. It is understood that the remaining length L3 of the output material can be measured by a relevant measuring device on the feed roller. Measuring the remaining length L3 of the output material is a function inherent in existing winding equipment, and there is no need to describe or limit the specific detection method for the remaining length L3 here. By comparing the remaining length L3 of the output material with the preset length value L0, a command can be issued promptly when the winding equipment needs to change rolls, thereby facilitating the measurement of the length of the output material before and after roll-changing using the method provided by this invention.

[0037] Further optionally, the preset length value L0 is 10m-30m. The preset length value L0 can be 10m, 12m, 14m, 16m, 18m, 20m, 22m, 24m, 26m, 28m, or 30m. Of course, the preset length value L0 can also be other values ​​within the 10m-30m range according to actual needs, and is not limited to the examples above. It is understandable that an excessively large preset length L0 will result in waste of output materials, while an excessively small preset length L0 will result in insufficient time for subsequent actions after the roll change command is issued, easily increasing the roll change failure rate. In this embodiment, controlling the preset length L0 within the range can both improve the utilization rate of output materials and reduce waste, and also allow sufficient time for subsequent actions after the roll change command is issued, reducing the roll change failure rate.

[0038] Optionally, the method for adjusting the thickness of the electrode sheet is to adjust the pressure of the electrode sheet forming roller 700 on the electrode sheet in the winding equipment. It is understood that the electrode sheet forming roller 700 is a pre-existing structure in the winding equipment. The method disclosed in this invention uses the existing structure in the winding equipment to adjust the electrode sheet thickness, which means that when implementing the method of this invention, there is no need to make excessive modifications to the winding equipment, thus facilitating the implementation of the method disclosed in this invention.

[0039] Alternatively, the electrode tab alignment can be further improved by adjusting the forming pressure W (MPa) of the electrode forming roller 700. The relationship between the electrode thickness compensation value h and the forming pressure W is as follows:

[0040] In the first case: when the forming pressure W < 0.17 MPa, the electrode thickness compensation value h and the forming pressure W satisfy the following relationship: W = h × K1, where K1 is a compensation constant, and the value of K1 ranges from 8 to 13.5 depending on the electrode model and compaction.

[0041] The second case: When the forming pressure W > 0.17 MPa, the thickness compensation value h of the electrode sheet and the forming pressure W satisfy the following relationship: W = h × K2, where K2 is a compensation constant. Depending on the electrode sheet model and the compaction, the value of K2 ranges from 3.45 to 5.5.

[0042] It should be noted here that, as mentioned above, in the actual control process, after calculating the thickness compensation value h of the electrode based on the length difference ΔL and the preset angle Φ, the specific value of the shaping pressure W is calculated according to the above formula. Then, by adjusting the shaping pressure W, the thickness of the electrode is adjusted to the theoretically calculated value, thereby achieving electrode tab alignment.

[0043] Taking the above diaphragm 400 roll change as an example, the preset angle Φ is set to 5400° and the preset difference ΔL0 is 3mm.

[0044] Before the roll change, the first conveying length L1 of the upper diaphragm 400 was recorded as 3696.37 mm after the single-roll winding needle 600 rotated a preset angle of 5400°. After the roll change, the second conveying length L2 of the new upper diaphragm 400 was recorded as 3693.24 mm after the single-roll winding needle 600 rotated a preset angle of 5400°. The length difference ΔL between the first and second conveying lengths L1 and L2 was -3.12 mm. Substituting this into the formula: the electrode thickness compensation value h = ((ΔL / (Φ / 360)) / 6.28) × 0.035, we can obtain h = -0.0012. Since the length difference ΔL is negative, this indicates that the upper diaphragm 400 after the roll change is thinner than the upper diaphragm 400 before the roll change. Therefore, it is necessary to increase the forming pressure W of the electrode forming roller 700. Assuming the current forming pressure W = 0.135 MPa, and taking K1 as 8.5, substituting into the formula W1 = h × K1, we get W1 = -0.0102 MPa. Therefore, the forming pressure W of the electrode forming roller 700 after the rewinding should be 0.135 MPa - (-0.0102 MPa), that is, W = 0.1452 MPa.

[0045] If the length difference ΔL is positive, it means that the upper diaphragm 400 after the roll change is thicker than the upper diaphragm 400 before the roll change, so the forming pressure W of the electrode forming roller 700 needs to be reduced.

[0046] In addition, in order to achieve visual display or manual adjustment of the first conveying length value L1, the second conveying length value L2, the length difference ΔL, the preset difference ΔL0, the thickness of the electrode sheet, and the preset angle Φ, a display panel for the above parameters can be added to the existing winding equipment, so that operators can have a more intuitive understanding of the electrode misalignment and electrode alignment.

[0047] In the description of this specification, references to terms such as "some embodiments," "other embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0048] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for improving the alignment of tabs in a wound battery, characterized in that, Includes the following steps: When the winding device’s roll change command is triggered, the first conveying length value L1 of the output material is recorded after the single roll needle rotates a preset angle Φ. After changing the raw material roll, after the single roll needle rotates by the preset angle Φ, record the second conveying length value L2 of the output raw material after the roll change; When the absolute value of the length difference ΔL between the first conveying length value L1 and the second conveying length value L2 exceeds the preset difference ΔL0, it is determined that the tab has deviated. The thickness of the electrode is adjusted according to the length difference ΔL; The method for adjusting the thickness of the electrode sheet is as follows: the thickness compensation value h of the electrode sheet is obtained according to the relationship between the length difference ΔL, the preset angle Φ and the thickness compensation value h of the electrode sheet; The pressure of the electrode forming roller on the electrode in the winding equipment is adjusted according to the electrode thickness compensation value h. in: The length difference ΔL, the preset angle Φ, and the thickness compensation value h of the electrode sheet satisfy the following relationship: h = ((ΔL / (Φ / 360)) / 6.28) × Q, where Q is a compensation constant and its range is 0.01-5; The thickness compensation value h of the electrode sheet and the forming pressure W of the electrode sheet forming roller satisfy the following relationship: When the shaping pressure W < 0.17 MPa, the thickness compensation value h of the electrode sheet and the shaping pressure W satisfy the relationship W = h × K1, where K1 ranges from 8 to 13.

5. When the shaping pressure W > 0.17 MPa, the thickness compensation value h of the electrode sheet and the shaping pressure W satisfy the relationship W = h × K2, where K2 ranges from 3.45 to 5.

5.

2. The method for improving tab alignment of a wound battery according to claim 1, characterized in that, The range of the preset difference ΔL0 is 1mm-5mm.

3. The method for improving tab alignment of a wound battery according to claim 1, characterized in that, The range of the preset angle Φ is 1080°-5400°.

4. The method for improving the tab alignment of a wound battery according to any one of claims 1-3, characterized in that, The output raw materials include at least one of positive electrode sheet, negative electrode sheet, upper diaphragm, or lower diaphragm.

5. The method for improving tab alignment of a wound battery according to claim 4, characterized in that, When the output raw material is the positive electrode and / or the negative electrode, the length difference ΔL and the thickness compensation value h of the electrode satisfy the following relationship: h=((ΔL / (Φ / 360)) / 6.28)×3.

6. The method for improving tab alignment of a wound battery according to claim 4, characterized in that, When the output raw material is the upper diaphragm and / or the lower diaphragm, the length difference ΔL and the thickness compensation value h of the electrode sheet satisfy the following relationship: h = ((ΔL / (Φ / 360)) / 6.28) × 0.

035.

7. The method for improving the tab alignment of a wound battery according to any one of claims 1-3, characterized in that, When the remaining length L3 of the output material is less than the preset length value L0, the winding device triggers the roll change command.

8. The method for improving tab alignment of a wound battery according to claim 7, characterized in that, The preset length value L0 is 10m-30m.

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