Method for Measuring the Winding Tightness of a Lithium-Ion Battery

Abstract

The present invention provides a measuring device and method for the winding tightness of a lithium-ion battery. The measuring device includes a rotating table, a pressing structure, a measuring structure, and a winding structure. An electrode fixing structure is provided on the rotating table. The pressing structure is used to press the battery electrode to be measured. The winding structure is used to collect the winding layer released by the battery electrode to be measured. The measuring structure includes a linear driving structure, a measuring indenter, a force sensor, a displacement sensor, and a processor. The linear driving structure is used to drive the measuring indenter to move back and forth. The force sensor and the displacement sensor are arranged on the measuring indenter. Both the force sensor and the displacement sensor are electrically connected to the processor. The processor is used to obtain the load-displacement curve of the measuring indenter, and the residual displacement of different winding layers after the battery electrode to be measured is unloaded can be obtained according to the load-displacement curve. The measuring device and method for the winding tightness of the lithium-ion battery can quantitatively judge the winding tightness of the battery electrode of the ion battery.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion battery cell detection, and more specifically, to a method for measuring the winding tightness of a lithium-ion battery. Background Art

[0002] Lithium-ion batteries are widely used in modern digital products, power tools, electric bicycles and other fields. In the manufacturing process of lithium-ion battery cells, the winding process is a very important production process to ensure the production quality of wound lithium-ion batteries. The tightness of the cell winding in the cell winding process not only affects the winding diameter of the cell and the tightness of the cell entering the case, but also affects the risk of pole piece breakage during the winding process and the liquid leakage ability of the cell during the subsequent liquid injection process.

[0003] At present, the adjustment of the winding tightness of lithium-ion battery cells is mainly achieved by adjusting the respective tension sizes of the diaphragm, the positive electrode plate and the negative electrode plate during winding. The judgment result is based on that the pole piece does not break and the cell can easily enter the case, and the judgment result depends more on subjective experience. Moreover, when switching to produce cells of different models of batteries, the same winding tension will affect the actual tightness of the cells, and it is difficult to distinguish the winding tightness of cells of different models of batteries subjectively. More importantly, the tightness of the cell will have an important impact on the stress magnitude and distribution caused by the repeated expansion and contraction of the positive and negative electrode plates during the subsequent cycling process of the cell, and this part of the impact cannot be compared by a relatively quantitative method at present. Summary of the Invention

[0004] An object of an embodiment of the present invention is to provide a device for measuring the winding tightness of a lithium-ion battery, which can quantitatively judge the winding tightness of a lithium-ion battery cell.

[0005] Another object of an embodiment of the present invention is to provide a method for measuring the winding tightness of a lithium-ion battery, which can quantitatively judge the winding tightness of a lithium-ion battery cell.

[0006] To achieve the above object, the technical solution adopted by the present invention is: In the first aspect of the present invention, a device for measuring the winding tightness of a lithium-ion battery is provided, including a rotating table, a pressing structure, a measuring structure and a winding structure;

[0007] The rotating table is provided with a battery cell fixing structure for fixing the battery cell to be tested, a pressing structure for pressing the battery cell to be tested, and a winding structure for collecting the winding layer released by the battery cell to be tested. The measuring structure includes a linear driving structure, a measuring indenter, a force sensor, a displacement sensor, and a processor. The linear driving structure is used to drive the measuring indenter to move so that the measuring indenter presses the battery cell to be tested. The force sensor and the displacement sensor are arranged on the measuring indenter. The force sensor is used to detect the pressure applied by the measuring indenter, and the displacement sensor is used to detect the displacement of the measuring indenter. Both the force sensor and the displacement sensor are electrically connected to the processor, and the processor is used to obtain the load-displacement curve of the measuring indenter and the residual displacements of different winding layers of the battery cell to be tested after the measuring indenter releases the pressure.

[0008] In one embodiment, the rotating table includes a first turntable and a second turntable. The outer peripheral surfaces of the first turntable and the second turntable are both circular. The first turntable is located in the middle of the second turntable, and the first turntable is arranged on the second turntable. The battery cell fixing structure is fixed at the center of the first turntable.

[0009] In one embodiment, an angle sensor is arranged on the first turntable, and the angle sensor is used to detect the rotation angle of the first turntable.

[0010] In one embodiment, the number of the pressing structures is two. Both of the two pressing structures include a servo motor, a support shaft, and a pressing wheel. The support shaft is fixedly connected to the servo motor, and the pressing wheel is mounted on the support shaft. The two pressing structures are arranged on a straight line and are respectively located on both sides of the battery cell fixing structure.

[0011] In one embodiment, the number of the measuring structures is two. The two measuring structures are arranged on a straight line and are respectively located on both sides of the battery cell fixing structure.

[0012] In one embodiment, a first slot and a second slot are formed in the second turntable. Both the first slot and the second slot pass through the center of the second turntable, and the first slot is perpendicular to the second slot.

[0013] The two pressing structures are located in the first slot, and the two measuring structures are located in the second slot. The pressing structures and the measuring structures can be lifted in the first slot and the second slot.

[0014] In one embodiment, the winding structure includes a reel and a driving motor, and the reel is connected to the output shaft of the driving motor.

[0015] The second aspect of the present invention provides a method for measuring the winding tightness of a lithium-ion battery cell. The method uses the measuring device for the winding tightness of a lithium-ion battery cell as described above. The method includes:

[0016] S1. Fix the battery cell to be measured on the cell fixing structure, open the winding layer of the battery cell to be measured, and fix the winding layer on the winding structure;

[0017] S2. Press the battery cell to be measured on the cell fixing structure by the pressing structure;

[0018] S3. Move the measuring indenter close to the battery cell to be measured, and the linear driving structure drives the measuring indenter to apply pressure for a preset time. The processor obtains the load-displacement curve of the measuring indenter, and obtains the residual displacement of the battery cell to be measured after unloading the pressure according to the load-displacement curve;

[0019] S4. Move the measuring structure away from the battery cell to be measured, rotate the turntable by 180 degrees, and tension the winding layer released by the battery cell to be measured during rotation on the winding structure;

[0020] S5. Repeat the above S3 and S4 to obtain the load-displacement curves of the measuring indenter corresponding to different rotation times and the residual displacements of the battery cell to be measured after unloading the pressure.

[0021] In one embodiment, the direction of applying pressure by the pressing structure when pressing the battery cell to be measured is perpendicular to the direction of applying pressure by the measuring indenter of the measuring structure.

[0022] The measuring device for the winding tightness of a lithium-ion battery cell provided by the present invention includes a turntable, a pressing structure, a measuring structure and a winding structure. A cell fixing structure is arranged on the turntable. The cell fixing structure is used to fix the battery cell to be measured. The pressing structure is used to press the battery cell to be measured. The winding structure collects the winding layer released by the battery cell to be measured. The measuring structure includes a linear driving structure, a measuring indenter, a pressure sensor, a displacement sensor and a processor. The linear driving structure is used to drive the measuring indenter to move so that the measuring indenter presses the battery cell to be measured. The force sensor and the displacement sensor are arranged on the measuring indenter. The force sensor is used to detect the pressure applied by the measuring indenter. The displacement sensor is used to detect the displacement of the measuring indenter. The force sensor and the displacement sensor are both electrically connected to the processor. The processor is used to obtain the load-displacement curve of the measuring indenter, and the residual displacements of different winding layers after unloading the pressure can be obtained according to the load-displacement curve. The present invention characterizes the tightness between the winding layers of the cell by the residual displacements of different winding layers after unloading the pressure, and can quantitatively judge the size of the winding tightness of the lithium-ion battery cell.

[0023] The method for measuring the winding tightness of a lithium-ion battery provided by the present invention includes: S1. Fix the battery cell to be measured on the cell fixing structure, open the winding layer of the battery cell to be measured, and fix the winding layer on the winding structure; S2. Press the battery cell to be measured on the cell fixing structure with the pressing structure; S3. Move the measuring indenter close to the battery cell to be measured, and the linear driving structure drives the measuring indenter to apply pressure for a preset time. The processor obtains the load-displacement curve of the measuring indenter, and obtains the residual displacement of the battery cell to be measured after unloading the pressure according to the load-displacement curve; S4. Move the measuring structure away from the battery cell to be measured, rotate the rotating table by 180 degrees, and tension the winding layer released by the battery cell to be measured during the rotation on the winding structure; S5. Repeat the above S3 and S4 to obtain the load-displacement curve of the measuring indenter corresponding to different rotation times and the residual displacement of the battery cell to be measured after unloading the pressure. This method can characterize the tightness between the winding layers of the cell through the residual displacement after unloading the pressure of different winding layers, and can quantitatively judge the size of the winding tightness of the lithium-ion battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0025] Figure 1 is a schematic structural diagram of a device for measuring the winding tightness of a lithium-ion battery provided by an embodiment of the present invention;

[0026] Figure 2 is a partial structural diagram of a device for measuring the winding tightness of a lithium-ion battery provided by an embodiment of the present invention;

[0027] Figure 3 is a schematic structural diagram of the device for measuring the winding tightness of a lithium-ion battery provided by an embodiment of the present invention after rotation;

[0028] Figure 4 is a partial structural diagram of the device for measuring the winding tightness of a lithium-ion battery provided by an embodiment of the present invention after rotation.

[0029] Among them, the reference numerals in the drawings are as follows:

[0030] 1 - rotating table;

[0031] 2 - pressing structure;

[0032] 3 - measuring structure;

[0033] 4 - winding structure;

[0034] 5 - Battery cell fixing structure;

[0035] 6 - Battery cell to be tested;

[0036] 11 - First turntable;

[0037] 12 - Second turntable;

[0038] 13 - First slot;

[0039] 14 - Second slot;

[0040] 21 - First pressing structure;

[0041] 22 - Second pressing structure;

[0042] 31 - Linear drive structure;

[0043] 32 - Measuring indenter;

[0044] 33 - First measuring mechanism;

[0045] 34 - Second measuring mechanism;

[0046] 211 - Servo motor;

[0047] 212 - Support shaft;

[0048] 213 - Pressing wheel. Detailed implementation manners

[0049] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0050] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0051] It should be understood that the orientation or positional relationship indicated by terms such as "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention.

[0052] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features.

[0053] The measuring device and method for the winding tightness of a lithium-ion battery provided by the present invention will be described below in conjunction with specific embodiments.

[0054] The first aspect of the present invention provides a measuring device for the winding tightness of a lithium-ion battery, including a rotating table 1, a pressing structure 2, a measuring structure 3, and a winding structure 4. Figure 1 It is a schematic structural diagram of the measuring device for the winding tightness of a lithium-ion battery provided by an embodiment of the present invention. Please refer to Figure 1 , a battery cell fixing structure 5 is arranged on the rotating table 1. The battery cell fixing structure 5 is used to fix the battery cell 6 to be measured. The pressing structure 2 is used to press the battery cell 6 to be measured. The winding structure 4 is used to collect the winding layers released by the battery cell 6 to be measured. The measuring structure 3 includes a linear driving structure 31, a measuring pressing head 32, a pressure sensor, a displacement sensor, and a processor. The linear driving structure 31 is used to drive the measuring pressing head 32 to move back and forth. The force sensor and the displacement sensor are arranged on the measuring pressing head 32. The force sensor is used to detect the pressure applied by the measuring pressing head 32. The displacement sensor is used to detect the displacement of the measuring pressing head 32. Both the force sensor and the displacement sensor are electrically connected to the processor. The processor is used to obtain the load-displacement curve of the measuring pressing head 32 and the residual displacement of different winding layers of the battery cell 6 to be measured after the measuring pressing head releases the pressure.

[0055] In this embodiment, the rotating table 1 is used to rotate the battery cell 6 to be measured, so as to release the winding layer and facilitate the measurement of the tightness of each layer of the battery cell 6 to be measured.

[0056] The battery cell fixing structure 5 of this embodiment is used to fix the battery cell 6 to be measured. The specific form of the battery cell fixing structure 5 in this embodiment is not particularly limited. The battery cell fixing structure 5 of this embodiment can be an expansion shaft, for example, it can be a pneumatic shaft. The pneumatic shaft is inserted into the center of the battery cell 6 to be measured to fix the battery cell to be measured on the pneumatic shaft.

[0057] In this embodiment, the pressing structure 2 presses the battery cell under test 6 during the rotation of the battery cell under test 6 and the measurement of the tightness of the battery cell under test 6. There is no special limitation on the specific form of the pressing structure in this embodiment.

[0058] In this embodiment, the winding structure 4 collects the released winding layer of the battery cell under test 6 after the winding layer of the battery cell under test 6 is released and maintains the tension in the released winding layer. There is no special limitation on the specific form of the winding structure 4 in this embodiment.

[0059] The measurement structure 3 of this embodiment includes a linear drive structure 31, a measurement indenter 32, a force sensor, a displacement sensor, and a processor (not shown in the figure). The linear drive structure 31 is used to drive the measurement indenter 32 to move back and forth to apply pressure to the measurement indenter 32. The force sensor and the displacement sensor are arranged on the measurement indenter 32. The force sensor is used to detect the pressure applied by the measurement indenter 32, and the displacement sensor is used to detect the displacement of the measurement indenter 32. The processor obtains the load-displacement curve of the measurement indenter, and the residual displacement after unloading the pressure of different winding layers can be obtained according to the load-displacement curve. There is no special limitation on the specific form of the pressure sensor and the displacement sensor in this embodiment.

[0060] Please refer to Figure 1 , further, the rotating table 1 includes a first turntable 11 and a second turntable 12. The outer peripheral surfaces of the first turntable 11 and the second turntable 12 are both circular. The first turntable 11 is located in the middle of the second turntable 12. The first turntable 11 is arranged on the second turntable 12, and the battery cell fixing structure 5 is fixed at the center of the first turntable 11. The first turntable 11 is located on the second turntable 12. When fixing the winding layer of the battery cell under test 6 by opening it, the tension of the winding layer of the battery cell under test 6 can be realized by rotating the first turntable 11 and the winding structure 4.

[0061] Further, an angle sensor is arranged on the first turntable 11. The angle sensor is used to detect the rotation angle of the first turntable 11. By arranging the angle sensor, the tester can judge the rotation angle of the first turntable 11 with reference to the display value of the angle sensor, ensuring the accuracy of the whole test.

[0062] Further, the pressing structure 2 includes a first pressing structure 21 and a second pressing structure 22. Both the first pressing structure 21 and the second pressing structure include a servo motor 211, a support shaft 212, and a pressing wheel 213. The support shaft 212 is fixedly connected to the servo motor 211, and the pressing wheel 213 is mounted on the support shaft 212. The first pressing structure 21 and the second pressing structure 22 are arranged in a straight line and are respectively located on both sides of the battery cell fixing structure 5. By providing the first pressing structure 21 and the second pressing structure 22, when the second turntable 12 rotates, the first pressing structure 21 and the second pressing structure 22 press the battery cell to be tested successively, ensuring that the battery cell to be tested 6 does not loosen, and avoiding the problem that the test result is inaccurate due to the battery cell to be tested 6 not being pressed tightly during the rotation process.

[0063] Please refer to Figure 2 and Figure 3 , further, the number of the measuring structures is two. The two measuring mechanisms are respectively a first measuring mechanism 33 and a second measuring mechanism 34. The first measuring mechanism 33 and the second measuring mechanism 34 are arranged in a straight line and are respectively located on both sides of the battery cell fixing structure 5.

[0064] Preferably, the second turntable 12 is provided with a first slot 13 and a second slot 14. Both the first slot 13 and the second slot 14 pass through the center of the second turntable 12, and the first slot 13 is perpendicular to the second slot 14;

[0065] The first pressing structure 21 and the second pressing structure 22 are located in the first slot 13, and the first measuring structure 33 and the second measuring structure 34 are located in the second slot 14. The first pressing structure 21 and the second pressing structure 22, the first measuring structure 33 and the second measuring structure 34 can be lifted in the first slot 13 and the second slot 14.

[0066] The winding structure 4 of this embodiment includes a reel and a driving motor. The reel is connected to the output shaft of the driving motor. The winding structure 4 of this embodiment collects the winding layer released by the battery cell to be tested by driving the reel to rotate through the driving motor.

[0067] The second aspect of the embodiment of the present invention provides a method for measuring the winding tightness of a lithium-ion battery. The method uses the measuring device for the winding tightness of a lithium-ion battery described in the above embodiment. The method includes:

[0068] S11. Fix the battery cell to be tested on the battery cell fixing structure, open the winding layer of the battery cell to be tested, and fix the winding layer on the winding structure;

[0069] Specifically, the center of the battery cell to be measured is fixed on the cell fixing structure through the expansion shaft. After unwrapping the winding layer of the battery cell to be measured, the winding layer can be fixed on the winding structure through the guiding tape.

[0070] S12. Press the battery cell to be measured on the cell fixing structure by the pressing structure;

[0071] Specifically, after the winding layer is fixed on the winding structure through the guiding tape, the pressing structure presses the battery cell to be measured.

[0072] S13. Move the measuring indenter close to the battery cell to be measured. The linear driving structure drives the measuring indenter to apply pressure for a preset time. The processor acquires the load-displacement curve of the measuring indenter, and obtains the residual displacement of the battery cell to be measured after unloading the pressure according to the load-displacement curve;

[0073] Specifically, when the measuring indenter moves close to the battery cell to be measured, the pressure sensor and displacement sensor arranged on the measuring indenter collect the pressure on the measuring indenter and the displacement of the measuring indenter when the measuring indenter applies pressure for a preset time. The processor obtains the load-displacement curve according to the pressure and displacement collected by the pressure sensor, and then the operator can obtain the residual displacement according to the load-displacement curve.

[0074] S14. Separate the measuring structure from the battery cell to be measured, rotate the rotating table by 180 degrees, and tension the winding layer released by the battery cell to be measured during rotation on the winding structure;

[0075] Specifically, when separating the measuring structure from the battery cell to be measured and the pressing structure presses the battery cell to be measured, rotate the rotating table by 180 degrees, and tension the winding layer released by the battery cell to be measured during rotation on the winding structure.

[0076] S15. Repeat the above S13 and S14 to obtain the load-displacement curves of the measuring indenter corresponding to different rotation times and the residual displacements of the battery cell to be measured after unloading the pressure.

[0077] Specifically, the strain rate of the measuring indenter applying pressure each time is the same, and the test time can be adjusted according to the material and tightness of the battery cell to be measured. The residual displacements corresponding to different rotation times are the winding tightness degrees of the corresponding winding layers of the battery cell to be measured. In this embodiment, the magnitude of the residual displacement is used to measure the winding tightness degrees of different layers of the battery cell to be measured. The larger the residual displacement, the looser the cell; conversely, the tighter the cell.

[0078] The method for measuring the winding tightness of the lithium-ion battery in this embodiment can characterize the tightness between the winding layers of the battery cell through the residual displacement after unloading the pressure of different winding layers, enabling quantitative judgment of the winding tightness of the lithium-ion battery cell, facilitating data comparison of the winding tightness of different battery cells, and optimizing the winding tension of the battery cell according to the winding tightness.

[0079] Preferably, the direction in which the pressing structure applies pressure when pressing the battery cell to be measured is perpendicular to the direction in which the measuring head of the measuring structure applies pressure. This avoids the pressing force of the pressing structure interfering with the pressure applied by the measuring head when pressing the battery cell to be measured.

[0080] In one embodiment of the present application, the method includes:

[0081] S21. Install the battery cell 6 to be measured on the first turntable 11;

[0082] Specifically, please refer to Figure 2 , the battery cell 6 to be measured can be fixed through the cell fixing structure 5. For example, the battery cell 6 to be measured is fixed by an expansion shaft.

[0083] S22. The pressing wheel 211 of the first pressing structure 21 presses the outer layer of the battery cell 6 to be measured;

[0084] Specifically, cut the outer adhesive tape layer of the battery cell 6 to be measured, bond the separator, negative electrode sheet, and positive electrode sheet of the wound layer after cutting to the guiding tape of the winding structure 4. The guiding tape is bonded to the reel of the winding structure 4, and the reel is connected to a driving motor. Rotate the winding structure 4 clockwise to make the guiding tape in a slightly tensioned state;

[0085] S23. The first measuring structure 33 moves towards the battery cell 6 to be measured. The linear driving structure 31 drives the measuring head 32 to apply pressure for a preset time. The processor obtains the load-displacement curve of the measuring head, and obtains the residual displacement of the current winding layer of the battery cell 6 to be measured after unloading the pressure according to the load-displacement curve;

[0086] Specifically, the first measuring structure 33 moves towards the battery cell 6 to be measured. Record the position when the reading detected by the pressure sensor on the first measuring structure 33 suddenly changes as the initial position. At this time, the displacement detected by the pressure sensor is ε0. Apply pressure to the battery cell 6 to be measured at a set strain rate, unload after acting for a set time, and obtain the load-displacement curve of this process. The displacement detected by the pressure sensor after the measuring head unloads is ε t , calculate the residual displacement ε r = ε t - ε0;

[0087] S24. Keep the first pressing structure 21 pressing the battery cell 6 to be measured, so that the first measuring structure 33 moves away from the battery cell 6 to be measured. Lower the second pressing structure 22 and the second measuring structure 34 below the rotating table 1. Rotate the second turntable 12 and the first turntable 11 clockwise by 180 degrees simultaneously. Then raise the second pressing structure 22 and the second measuring structure 34 above the rotating table 1. Press the battery cell 6 to be measured with the second pressing structure 22. Release the first pressing structure 21 and rotate the winding structure 4 clockwise to tension the released winding layer.

[0088] Specifically, please refer to Figure 2 and Figure 3 , keep the first pressing structure 21 pressing the battery cell 6 to be measured, so that the first measuring structure 33 moves away from the battery cell 6 to be measured. Lower the second pressing structure 22 and the second measuring structure 34 below the rotating table 1. Rotate the second turntable 12 and the first turntable 11 clockwise by 180 degrees simultaneously. Then raise the second pressing structure 22 and the second measuring structure 34 above the rotating table 1. Press the battery cell 6 to be measured with the second pressing structure 22. Release the first pressing structure 21 and rotate the winding structure 4 clockwise to tension the released winding layer, ensuring that the winding core will not loosen during rotation, which may affect the measurement accuracy.

[0089] S25. Move the measuring head of the second measuring structure 34 towards the battery cell 6 to be measured to obtain the load-displacement curve during this process and the residual displacement of the current winding layer of the battery cell 6 to be measured.

[0090] Specifically, please refer to Figure 4 , move the measuring head of the second measuring structure 34 towards the battery cell 6 to be measured. When the force sensor on the measuring structure 3 monitors a sudden change in the reading of the pressure sensor, the displacement detected by the pressure sensor is recorded as ε0. Apply a force to the battery cell 6 to be measured at the same strain rate as in S23 for a preset time and then unload. The processor obtains the load-displacement curve during this process, where the displacement detected by the pressure sensor after the measuring head is unloaded is ε t , and calculate the residual displacement ε r = ε t - ε0;

[0091] S26. Repeat steps S24 and S25, record the load-displacement curves corresponding to different rotation times and calculate the corresponding residual displacement ε r of the current winding layer of the battery cell 6 to be measured;

[0092] S27. By plotting the residual displacements ε r corresponding to different rotation times, obtain the tightness of different layers of the battery cell 6 to be measured.

[0093] In this embodiment, the direction in which the first pressing structure 21 applies pressure when pressing the battery cell 6 to be measured is perpendicular to the direction in which the measuring indenter of the first measuring mechanism 33 applies pressure, and the direction in which the second pressing structure 22 applies pressure when pressing the battery cell 6 to be measured is perpendicular to the direction in which the measuring indenter of the second measuring mechanism 34 applies pressure.

[0094] The method for measuring the winding tightness of the lithium-ion battery can use the method of obtaining the load-displacement curve of the measuring indenter and the residual displacement of the battery cell to be measured to characterize the winding tightness between the layers of the lithium-ion battery cell, and can quantitatively judge the size of the winding tightness of the lithium-ion battery cell, which is convenient for data comparison between different winding tightnesses of the battery cells, and the winding tension can be optimized according to the winding tightness of the battery cell.

[0095] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for measuring the winding tightness of a lithium-ion battery, characterized in that, Measure with a measuring device for the winding tightness of a lithium-ion battery cell. The measuring device includes a rotating table, a pressing structure, a measuring structure, and a winding structure. A battery cell fixing structure is provided on the rotating table, and the battery cell fixing structure is used to fix the battery cell to be measured. The measuring structure includes a linear driving structure, a measuring indenter, a force sensor, a displacement sensor, and a processor. The linear driving structure is used to drive the measuring indenter to move so that the measuring indenter presses the battery cell to be measured. The force sensor and the displacement sensor are arranged on the measuring indenter. The force sensor is used to detect the pressure applied by the measuring indenter, and the displacement sensor is used to detect the displacement of the measuring indenter. Both the force sensor and the displacement sensor are electrically connected to the processor. The method includes: S1. Fix the battery cell to be measured on the battery cell fixing structure, open the winding layer of the battery cell to be measured, and fix the winding layer on the winding structure. The winding structure is used to collect the winding layer released by the battery cell to be measured. S2. Press the battery cell to be measured on the battery cell fixing structure with the pressing structure. S3. Move the measuring indenter close to the battery cell to be measured. The linear driving structure drives the measuring indenter to apply pressure for a preset time. The processor obtains the load-displacement curve of the measuring indenter, and obtains the residual displacement of the battery cell to be measured after unloading the pressure according to the load-displacement curve. S4. Move the measuring structure away from the battery cell to be measured, rotate the rotating table by 180 degrees, and tension the winding layer released by the battery cell to be measured during the rotation on the winding structure. S5. Repeat the above S3 and S4 to obtain the load-displacement curves of the measuring indenter corresponding to different rotation times and the residual displacements of the battery cell to be measured after unloading the pressure.

2. The method for measuring the winding tightness of a lithium-ion battery according to claim 1, characterized in that: The rotating table includes a first turntable and a second turntable. The outer peripheral surfaces of the first turntable and the second turntable are both circular. The first turntable is located in the middle of the second turntable. The first turntable is arranged on the second turntable, and the battery cell fixing structure is fixed at the center of the first turntable.

3. The method for measuring the winding tightness of a lithium-ion battery according to claim 2, characterized in that: An angle sensor is provided on the first turntable, and the angle sensor is used to detect the rotation angle of the first turntable.

4. The method for measuring the winding tightness of a lithium-ion battery according to claim 2, characterized in that: The number of the pressing structures is two. Both pressing structures include a servo motor, a support shaft, and a pressing wheel. The support shaft is fixedly connected to the servo motor, and the pressing wheel is installed on the support shaft. The two pressing structures are arranged on a straight line and are respectively located on both sides of the battery cell fixing structure.

5. The method for measuring the winding tightness of a lithium-ion battery according to claim 4, characterized in that: The number of the measuring structures is two. The two measuring structures are arranged on a straight line and are respectively located on both sides of the battery cell fixing structure.

6. The method for measuring the winding tightness of a lithium-ion battery according to claim 5, wherein: A first slot and a second slot are formed in the second turntable. Both the first slot and the second slot pass through the center of the second turntable. The first slot is perpendicular to the second slot. The two pressing structures are located in the first slot, and the two measuring structures are located in the second slot. The pressing structure and the measuring structure can be lifted in the first slot and the second slot.

7. The method for measuring the winding tightness of a lithium-ion battery according to claim 1, characterized in that: The winding structure includes a reel and a driving motor, and the reel is connected to the output shaft of the driving motor.

8. The method for measuring the winding tightness of a lithium-ion battery according to claim 1, characterized in that: When pressing the battery cell to be measured, the direction in which the pressing structure applies pressure is perpendicular to the direction in which the measuring head of the measuring structure applies pressure.

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