Lithium battery winding device and control method thereof

Abstract

The application relates to a lithium battery winding device and a control method thereof. The device comprises: an unwinding shaft for releasing a material belt on the unwinding shaft; a winding needle for winding the material belt released by the unwinding shaft; a material belt winding drive roller located between the unwinding shaft and the winding needle, and the material belt is wound around the surface of the material belt winding drive roller; and a material belt winding drive servo motor for driving the material belt winding drive roller to rotate at a given speed, wherein the given speed is associated with the actual rotation speed of the winding needle. Through the application, the adjustment compensation of the tension and speed in the winding and acceleration stages can be realized through the material belt winding drive roller, and then the precise control of the diaphragm tension between the material belt winding drive roller and the winding needle is realized, so that the S-shaped curve in the inner circle of the battery cell is eliminated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium battery, and particularly relates to a lithium battery winding device and a control method thereof. BACKGROUND

[0002] The winding process of the lithium battery is usually a four-layer structure of positive electrode-separator-negative electrode-separator, and the extension rate (or stretchability) of the separator is larger than that of the electrode sheet. When winding, the winding acceleration is large, and the separator needs to overcome the acceleration inertia moment of all rollers to cause the separator tension of the inner circle of the battery cell to be large. However, after winding, the winder is pulled out, and the tension of the inner circle of the separator is released to a certain extent, which causes the inner circle of the separator to shrink, and the extension rate of the electrode sheet is much smaller than that of the separator, and the inner circle of the electrode sheet does not shrink relative to the separator, which causes the inner circle of the separator to squeeze the electrode sheet to form an inner circle S type.

[0003] If the inner circle S type is serious, it will cause the inner circle of the battery cell to be wrinkled after forming, and finally cause the battery cell to have insufficient capacity or other safety problems. Therefore, analyzing and researching the causes of the inner circle S type of the battery cell and the control method for eliminating the S type have very important significance for improving the consistency and safety of the battery cell quality. SUMMARY

[0004] The present application provides a lithium battery winding device and a method thereof to solve the technical problem of the inner circle of the battery cell being wrinkled after forming. The technical scheme of the present application is as follows:

[0005] According to a first aspect of an embodiment of the present application, a lithium battery winding device is provided, and the device comprises: a unwinding shaft for releasing a tape on the unwinding shaft; a winder for winding the tape released by the unwinding shaft; a tape winding drive roller located between the unwinding shaft and the winder, and the tape is wound around the surface of the tape winding drive roller; a tape winding drive servo motor for driving the tape winding drive roller to rotate at a given speed, wherein the given speed is associated with the actual rotation speed of the winder.

[0006] Further, the tape winding drive roller is arranged adjacent to the winder, and when the tape is wound, the tape directly enters the winder for winding after passing through the tape winding drive roller.

[0007] Further, when the moment of the tape winding drive roller is less than the moment limit value, the tape winding drive servo motor is used to drive the tape winding drive roller to rotate at a given speed.

[0008] Further, the given speed V=K*V1, wherein V1 is the actual rotation speed of the winder, and K is a proportional coefficient, 0

[0009] Further, when the torque of the material tape winding drive roller is greater than or equal to the torque limiting amplitude, the material tape winding drive servo motor is used to output a given torque, so that the torque of the material tape winding drive roller is less than the torque limiting amplitude.

[0010] Further, when the winding needle is in the uniform speed stage, the torque limiting amplitude is

[0011] T limit =T set +T friction

[0012] wherein T set is a torque corresponding to a material tape tension setting value, and T friction is an equivalent friction torque of all rollers between the material tape winding drive roller and the unwinding shaft.

[0013] Further, when the winding needle is in the acceleration or deceleration stage, the torque limiting amplitude is

[0014] T limit =T set +T friction +T acc

[0015] wherein T set is a torque corresponding to a material tape tension setting value, T friction is an equivalent friction torque of all rollers between the material tape winding drive roller and the unwinding shaft, and T acc is an acceleration torque compensation.

[0016] Further, the device further comprises at least one roller, which is located between the unwinding shaft and the winding needle, and the material tape is wound around the surface of the roller.

[0017] Further, the roller comprises a swing rod floating roller.

[0018] According to a second aspect of the embodiments of the present application, a lithium battery winding control method is provided, which is used for the lithium battery winding device according to any one of the first aspect of the embodiments of the present application, and the method comprises the following steps: monitoring the torque of the material tape winding drive roller; when the torque of the material tape winding drive roller is less than a torque limiting amplitude, the material tape winding drive servo motor drives the material tape winding drive roller to rotate at a given speed; and when the torque of the material tape winding drive roller is greater than or equal to the torque limiting amplitude, the material tape winding drive servo motor outputs a given torque, so that the torque of the material tape winding drive roller is less than the torque limiting amplitude.

[0019] The technical solutions provided by the embodiments of the present application at least bring the following beneficial effects:

[0020] In the embodiment of the present application, a lithium battery winding device is provided, which comprises: an unwinding shaft for releasing a material belt on the unwinding shaft; a winding needle for winding the material belt released by the unwinding shaft; a material belt winding drive roller located between the unwinding shaft and the winding needle, and the material belt is wound around the surface of the material belt winding drive roller; a material belt winding drive servo motor for driving the material belt winding drive roller to rotate at a given speed, wherein the given speed is associated with the actual rotation speed of the winding needle. Through the embodiment of the present application, the adjustment and compensation of the tension and speed in the winding and acceleration stages can be realized by the material belt winding drive roller, and then the precise control of the diaphragm tension between the material belt winding drive roller and the winding needle is realized, so as to eliminate the S-shaped curve in the inner circle of the battery cell.

[0021] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0022] The accompanying drawings incorporated in and forming a part of the specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the application; they should not be considered as unduly limiting the application.

[0023] Figure 1 is a structural schematic diagram of a lithium battery winding device provided by the embodiment of the present application;

[0024] Figure 2 is a flowchart of a lithium battery winding control method provided by the embodiment of the present application.

[0025] Reference signs:

[0026] 1-unwinding shaft 2-winding needle 3-material belt winding drive roller

[0027] 4-material belt winding drive servo motor 5-swinging rod floating roller DETAILED DESCRIPTION

[0028] In order for those skilled in the art to better understand the technical solutions of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings.

[0029] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0030] The winding process of lithium batteries typically involves winding a four-layer structure consisting of a positive electrode, a separator, a negative electrode, and another separator. The separator has a greater elongation (or elasticity) than the electrode. During the winding process, the in-winding acceleration is relatively large, and the separator has to overcome the acceleration inertia torque of all the rollers, resulting in greater tension in the separator within the cell. However, after winding, when the winding needle is pulled out, the tension in the separator within the inner ring is released to some extent, causing the separator to shrink. Since the elongation of the electrode is much smaller than that of the separator, the electrode within the inner ring does not shrink much compared to the separator. This results in the separator within the inner ring squeezing the electrode to form an inner S-shape.

[0031] If this inner S-shape is severe, it can cause wrinkles in the inner ring after the cell is formed, ultimately leading to insufficient cell capacity or other safety issues.

[0032] Based on this, embodiments of this application provide a lithium battery winding device, such as... Figure 1 As shown, the device includes: an unwinding shaft 1 for releasing the strip on the unwinding shaft 1; a winding needle 2 for winding the strip released by the unwinding shaft 1; a strip in-winding drive roller 3 located between the unwinding shaft 1 and the winding needle 2, with the strip wound around the surface of the strip in-winding drive roller 3; and a strip in-winding drive servo motor 4 for driving the strip in-winding drive roller 3 to rotate at a given speed, wherein the given speed is related to the actual rotation speed of the winding needle 2.

[0033] In the embodiments of this application, such as Figure 1 As shown, the material strip in-winding drive roller 3 can be arranged adjacent to the winding needle 2. When the material strip is being wound, after passing through the material strip in-winding drive roller 3, the material strip directly enters the winding needle 2 for winding.

[0034] In this embodiment, at least one guide roller may be included between the unwinding shaft 1 and the feed roll drive roller 3, and the guide roller may include a rocker arm floating roller 5, such as... Figure 1As shown, the unwinding shaft 1 is sequentially provided with an over roller, a swing rod floating roller 5, an over roller, an over roller, a material belt into winding driving roller 3 and a winding needle 2. The material belt is released from the unwinding shaft 1 and sequentially winds around the surface of the over roller, the swing rod floating roller 5, the material belt into winding driving roller 3, the over roller and the winding needle 2. When the winding needle 2 starts to wind the material, the material belt is released from the unwinding shaft 1 and sequentially passes through the surface of the over roller and the material belt into winding driving roller 3 and finally enters the winding needle 2 for winding.

[0035] In the embodiment of the present application, by adding a material belt into winding driving roller 3 between the over roller and the winding needle 2 and driving by the material belt into winding driving servo motor 4, the equivalent friction and inertia of all over rollers can be compensated, so as to ensure that the tension between the material belt into winding driving roller 3 and the winding needle 2 meets the process requirements.

[0036] In the embodiment of the present application, when the torque of the material belt into winding driving roller 3 is less than the torque limiting amplitude, the material belt into winding driving servo motor 4 is used to drive the material belt into winding driving roller 3 to rotate at a given speed.

[0037] In the embodiment of the present application, the material belt into winding driving servo motor 4 can be set to a speed control mode to output at a given speed.

[0038] In the embodiment of the present application, the given speed V=K*V1, wherein V1 is the actual rotating speed of the winding needle 2, and K is a proportional coefficient, 0

[0039] In the embodiment of the present application, the actual rotating speed of the winding needle 2 can be measured by a speed sensor, then the given speed can be calculated based on the above formula, and then the material belt into winding driving servo motor 4 can drive the material belt into winding driving roller 3 to rotate at the given speed.

[0040] In the embodiment of the present application, the proportional coefficient K is slightly less than 1, so that there is a slight speed difference between the material belt into winding driving roller 3 and the winding needle 2, so that the tension of the material belt such as a diaphragm between the material belt into winding driving roller 3 and the winding needle 2 can meet the process requirements.

[0041] In the embodiment of the present application, when the torque of the material belt into winding driving roller 3 is greater than or equal to the torque limiting amplitude, the material belt into winding driving servo motor 4 is used to output a given torque, so that the torque of the material belt into winding driving roller 3 is less than the torque limiting amplitude.

[0042] In the embodiment of the present application, torque limiting protection can be added in the process of following the winding needle 2 by the material belt into winding driving roller 3, so that the diaphragm tension between the material belt into winding driving roller 3 and the winding needle 2 can always meet the preset process requirements and will not fluctuate greatly.

[0043] In the embodiment of the present application, the torque limiting amplitude varies according to the running state of the winding needle 2, when the winding needle 2 is in the uniform speed stage, the torque limiting amplitude is

[0044] T limit = T set + T friction

[0045] Wherein, T set is the torque corresponding to the tension setting value of the material belt, T friction is the equivalent friction torque of all the rollers between the material belt winding drive roller 3 and the unwinding shaft 1, that is, when the winding needle 2 is in the uniform speed stage, the size of the torque limiting amplitude is the sum of the torque corresponding to the tension value of the material belt and the equivalent friction torque of the roller.

[0046] In the embodiment of the present application, when the winding needle 2 is in the acceleration or deceleration stage, the torque limiting amplitude is

[0047] T limit = T set + T friction + T acc

[0048] Wherein, T set is the torque corresponding to the tension setting value of the material belt, T friction is the equivalent friction torque of all the rollers between the material belt winding drive roller 3 and the unwinding shaft 1, T acc is the acceleration torque compensation.

[0049] In the embodiment of the present application, the acceleration torque compensation is related to the size of the equivalent inertia and angular acceleration, that is, the torque limitation in the acceleration stage also needs to consider the influence of the acceleration torque. When in the deceleration stage, the acceleration is negative, the value of the acceleration torque compensation is also negative, which is equivalent to reducing the torque; when in the acceleration stage, the acceleration is positive, the value of the acceleration torque compensation is also positive, which is equivalent to increasing the torque.

[0050] In the embodiment of the present application, the speed loop can be the main control loop and the torque loop can be the protection loop, when the speed loop is saturated, the material belt winding drive servo motor 4 outputs a given torque, so that the torque of the material belt winding drive roller 3 is less than the torque limiting amplitude, thereby playing a protection role and preventing the runaway caused by the wrong position of the speed calculation; and when the torque of the material belt winding drive roller 3 is less than the torque limiting amplitude, the speed loop is immediately desaturated, and the speed loop works.

[0051] In the embodiment of the present application, the material belt can be a diaphragm or other material belt with a certain elongation.

[0052] In the embodiment of the present application, the lithium battery winding device can be applied to the occasions of the separator tension control on all winding machines, and is also applicable to other occasions requiring stable tension control.

[0053] In the embodiment of the present application, the adjustment and compensation of the tension and speed in the winding and acceleration stages can be realized by the material tape winding drive roller 3, and then the precise control of the separator tension between the material tape winding drive roller 3 and the winding needle 2 is realized, so as to eliminate the S-shaped inner circle of the battery cell and ensure the consistency and safety of the battery cell quality.

[0054] The embodiment of the present application also provides a lithium battery winding control method, which is used for the lithium battery winding device in any of the embodiments of the present application. Figure 2 As shown in the figure, the method can include:

[0055] S201: monitoring the torque of the material tape winding drive roller 3;

[0056] S203: when the torque of the material tape winding drive roller 3 is less than the torque limiting amplitude value, the material tape winding drive servo motor 4 drives the material tape winding drive roller 3 to rotate at a given speed;

[0057] S205: when the torque of the material tape winding drive roller 3 is greater than or equal to the torque limiting amplitude value, the material tape winding drive servo motor 4 outputs a given torque, so that the torque of the material tape winding drive roller 3 is less than the torque limiting amplitude value.

[0058] In the embodiment of the present application, the torque of the material tape winding drive roller can be measured by a torque sensor.

[0059] In the embodiment of the present application, when the torque of the material tape winding drive roller 3 is less than the torque limiting amplitude value, the material tape winding drive servo motor 4 is in the speed control mode.

[0060] When the torque of the material tape winding drive roller 3 is greater than or equal to the torque limiting amplitude value, the material tape winding drive servo motor 4 outputs a given torque, so that the torque of the material tape winding drive roller 3 is less than the torque limiting amplitude value, thereby playing a protective role and preventing runaway caused by speed calculation dislocation.

[0061] The composition of the lithium battery winding control device for executing the lithium battery winding control method in the embodiment of the present application and the specific way of working have been described in detail in the above-mentioned embodiment of the lithium battery winding control device, and will not be described in detail here.

[0062] Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the application being indicated by the following claims.

[0063] It is to be understood that the application is not limited to the precise construction herein disclosed and shown in the drawings, and that various changes in shape, size and arrangements of parts can be made without departing from the scope of the application. The scope of the application is only limited by the appended claims.

Claims

1. A lithium battery winding device, characterized by, The device comprises: a releasing shaft for releasing a tape from the releasing shaft; a winding needle for winding the tape released from the releasing shaft; a tape winding drive roller located between the releasing shaft and the winding needle, the tape being wound around the surface of the tape winding drive roller; a tape winding drive servo motor for driving the tape winding drive roller to rotate, when the torque of the tape winding drive roller is less than a torque limiting amplitude, the tape winding drive servo motor is used to drive the tape winding drive roller to rotate at a given speed, wherein the given speed is associated with the actual rotation speed of the winding needle; and / or, when the torque of the tape winding drive roller is greater than or equal to the torque limiting amplitude, the tape winding drive servo motor is used to output a given torque, so that the torque of the tape winding drive roller is less than the torque limiting amplitude; when the winding needle is in the uniform speed stage, the torque limiting amplitude is T limit = T set + T friction The torque limit amplitude is T when the roll pin is in an acceleration or deceleration phase limit = T set + T friction + T acc wherein T set is the torque corresponding to the tension set value of the material web, T friction is the equivalent friction torque of all the over-rollers between the material web in-feed drive roller and the unwind shaft, T acc is the acceleration torque compensation.

2. The lithium battery winding apparatus according to claim 1, wherein The tape winding drive roller is located adjacent to the winding needle, and when the tape is wound, the tape directly enters the winding needle for winding after passing through the tape winding drive roller.

3. The lithium battery winding apparatus according to claim 1, wherein The given speed V=K*V1, wherein V1 is the actual rotation speed of the winding needle, K is a proportional coefficient, and 0 4. The lithium battery winding apparatus according to claim 1, wherein The device further comprises at least one passing roller located between the releasing shaft and the winding needle, and the tape is wound around the surface of the passing roller.

5. The lithium battery winding apparatus according to claim 4, wherein The passing roller comprises a swing rod floating roller.

6. A lithium battery winding control method for the lithium battery winding apparatus as claimed in any one of claims 1 to 5, characterized by, The method comprises: monitoring the torque of the tape winding drive roller; when the torque of the tape winding drive roller is less than the torque limiting amplitude, the tape winding drive servo motor drives the tape winding drive roller to rotate at a given speed; when the torque of the tape winding drive roller is greater than or equal to the torque limiting amplitude, the tape winding drive servo motor outputs a given torque, so that the torque of the tape winding drive roller is less than the torque limiting amplitude.

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