Film layer thickness measurement apparatus, method, and battery cell production line

Abstract

This application discloses a film thickness measuring device, method, and production line for battery cells. The film is used in the battery cell. The film thickness measuring device includes a winding mechanism, a detection device, and a calculation unit. The winding mechanism includes a winding roller for winding the film. The detection device is used to detect the length of the film wound onto the winding roller and the corresponding rotation angle of the winding roller; or, the detection device is used to detect the length of the film unwound from the winding roller and the corresponding rotation angle of the winding roller. The calculation unit is configured to calculate the film thickness based on the film length and the rotation angle of the winding roller. By obtaining the film thickness based on the film length and the rotation angle of the winding roller, the measurement process is less likely to damage the film, is less affected by ambient light and the surface characteristics of the separator, and has better measurement accuracy.

Description

Technical Field

[0001] This application relates to the field of battery manufacturing technology, and more specifically, to a film thickness measuring device, a method, and a production line for a single battery cell. Background Technology

[0002] As a key component of a battery cell, accurately measuring the thickness of the separator is of great significance for controlling the production quality of battery cells and improving their performance.

[0003] Application content

[0004] This application provides a film thickness measurement device, method, and battery cell production line to solve the problem of film thickness measurement in battery cells.

[0005] In a first aspect, embodiments of this application provide a film thickness measuring device, the film being used in a battery cell, comprising: a winding mechanism including a winding roller for winding the film; a detection device for detecting the length of the film wound onto the winding roller and the corresponding rotation angle of the winding roller; or, the detection device for detecting the length of the film unwound from the winding roller and the corresponding rotation angle of the winding roller; and a calculation unit configured to obtain the thickness of the film based on the length of the film and the rotation angle of the winding roller.

[0006] In the above technical solution, the thickness of the film layer is calculated by detecting the length of the film layer wound onto the winding roller and the corresponding rotation angle of the winding roller, or by detecting the length of the film layer unwound from the winding roller and the corresponding rotation angle of the winding roller. Therefore, the film layer thickness measuring device of this application has the following advantages: First, in the process of film layer thickness measurement, only the length of the film layer and the rotation angle of the winding roller are measured, without squeezing the film layer, so the measurement process is less likely to damage the film layer; Second, the obtained film layer thickness reflects the overall thickness of a section of the film layer, rather than the thickness at a certain position of the film layer, so it has better reference significance for actual production, higher accuracy, and the obtained value can better guide production; Third, the measured length of the film layer has little correlation with the characteristics of the film layer surface, so the measurement process of this application is less affected by ambient light and the surface characteristics of the isolation film, and the measurement accuracy is better.

[0007] In some embodiments, the film layer is a separator for the battery cell, and the separator is used to separate the positive electrode and the negative electrode of the battery cell.

[0008] In the above technical solution, the measurement process of the film thickness measuring device is less affected by the characteristics of the isolation film itself, and can better adapt to the characteristics of the isolation film itself, resulting in higher measurement accuracy and precision.

[0009] In some embodiments, the film layer is the base film of the separator of the battery cell, and the separator is used to separate the positive electrode and the negative electrode of the battery cell.

[0010] The above technical solution can reduce the impact of the measurement error of the detection device on the measurement of the thickness of the base film, making the measured thickness of the base film more accurate.

[0011] In some embodiments, the film thickness measuring device further includes a control terminal, which is configured to determine whether the thickness of the film is within a preset range and provide a prompt.

[0012] In the above technical solution, by providing prompts, users can promptly obtain information about the thickness of the film layer without manual monitoring, which helps to improve the automation level of the film thickness measurement equipment.

[0013] In some embodiments, the detection device includes a roller that is rotatable, the film layer is supported on the roller, and the detection device is configured to calculate the length of the film layer based on the circumference of the roller and the number of rotations.

[0014] In the above technical solution, the length of the film layer is calculated based on the circumference and number of rotations of the roller, resulting in high accuracy of the detection results and minimal impact from the surface characteristics of the film layer.

[0015] In some embodiments, the film thickness measuring device further includes a tension control mechanism, which is spaced apart from the winding mechanism. The film is supported by the tension control mechanism, which is used to control the tension of the film within a set range.

[0016] In the above technical solution, the tension of the film layer is controlled by setting a tension control mechanism. On the one hand, this is beneficial for the smooth winding or unwinding of the film layer; on the other hand, it is beneficial for improving the accuracy of the measured length of the film layer.

[0017] In some embodiments, the setting range is 60 kgf to 500 kgf.

[0018] In the above technical solution, the tension on the film layer will not be too small, so the film layer is less likely to slip or shift during transportation after winding, resulting in uneven edges; the tension on the film layer will not be too large, which will cause scratches or breakage of the film layer. In addition, it is also conducive to the accurate measurement of the film layer thickness.

[0019] In some embodiments, the detection device includes an angle detection device, the winding mechanism includes a drive motor, the rotation shaft of the drive motor is connected to the winding roller to drive the winding roller to rotate, and the angle detection device is disposed on the rotation shaft of the drive motor for detecting the rotation angle of the winding roller.

[0020] In the above technical solution, by setting the angle detection device on the rotating shaft of the drive motor, the position of the angle detection device does not need to be moved when the winding roller is removed, and the angle detection device does not need to be repeatedly disassembled and installed, making it more convenient to use and lower in cost.

[0021] In some embodiments, the film thickness measuring device further includes a guide roller, which is arranged spaced apart from the winding roller, and the guide roller is rotatable and used to support the film.

[0022] In the above technical solution, by setting a guide roller to support the film layer moving along the set path, the guide roller can absorb system vibration and reduce the shaking of the film layer when it moves at high speed. At the same time, it is also used to guide the film layer to move along the set path and reduce deviation or twisting.

[0023] In some embodiments, the detection device is configured to: repeatedly detect the length of the film layer and the corresponding rotation angle of the winding roller during the process of unwinding or rewinding the film layer by the winding roller; according to the detection time sequence, the rotation angle of the winding roller detected for the first time is θ1, the length of the film layer is L1, and the rotation angle of the winding roller detected for the nth time is θ n The length of the film layer is L n , where θ n -θ n-1 =2mπ, where m is a positive integer; the calculation unit is configured to: fit the obtained data to obtain a fitting function of the length of the film layer changing with the rotation angle of the winding roller, and differentiate the fitting function to obtain a first linear function, the slope of the first linear function being the thickness of the film layer.

[0024] In the above technical solution, it is not necessary to measure or know the initial radius of the winding roller, and the detection process can begin when the film layer has been wound to any number of turns. The method has good flexibility and can be adapted to more application scenarios. By fitting the obtained data to obtain the final film thickness, the influence of measurement error can be effectively reduced, resulting in better accuracy of the obtained film thickness.

[0025] In some embodiments, the detection device is configured to: repeatedly detect the length of the film layer and the corresponding rotation angle of the winding roller during the process of unwinding or rewinding the film layer by the winding roller; according to the detection time sequence, the rotation angle of the winding roller detected for the first time is θ1, the length of the film layer is L1, and the rotation angle of the winding roller detected for the nth time is θ n The length of the film layer is L n , where θ n -θ n-1 =2mπ, where m is a positive integer; the calculation unit is configured to: calculate the length increment ΔL of the film layer detected multiple times, ΔL1 = L2 - L1, ΔL n-1 =L n -L n-1 ; Calculate the rotation angle increment Δθ of the winding roller for multiple tests, Δθ1=θ2-θ1, Δθ n-1 =θ n -θ n-1 The obtained data is fitted to obtain a second linear function that describes the change in the length increment of the film layer as a function of the rotation angle increment of the winding roller, and the slope of the second linear function is the thickness of the film layer.

[0026] In the above technical solution, it is not necessary to measure or know the initial radius of the winding roller, and the detection process can begin when the film layer has been wound to any number of turns. The method has good flexibility and can be adapted to more application scenarios. By fitting the obtained data to obtain the final film thickness, the influence of measurement error can be effectively reduced, resulting in better accuracy of the obtained film thickness.

[0027] In some embodiments, the detection device is configured to: detect the length of the film layer twice during the process of the winding roller winding a complete turn of the film layer to obtain the length change value ΔD of the film layer, and detect the rotation angle of the winding roller twice to obtain the rotation angle change value Δα of the winding roller; the calculation unit is configured to: calculate the film layer thickness t of the turn using the following formula: ΔD=(r0+(n-1)t)Δα, where r0 is the initial radius of the winding roller and n is the number of turns; calculate the film layer thickness of multiple turns, fit the obtained data to obtain a constant function of the film layer thickness changing with the number of turns, and the constant value of the constant function is the thickness of the film layer.

[0028] In the above technical solution, directly calculating the film thickness corresponding to multiple turns can easily remove values ​​with large film thickness deviations, reducing the impact of large deviations on the data fitting process. By fitting the obtained data to obtain the final film thickness, the influence of measurement errors can be effectively reduced, resulting in better accuracy of the obtained film thickness.

[0029] Secondly, embodiments of this application also provide a method for measuring film thickness, employing the film thickness measuring device described in any of the above embodiments, the film thickness measuring method comprising:

[0030] The length of the film layer wound onto the winding roller and the corresponding rotation angle of the winding roller are detected, or the length of the film layer unwound from the winding roller and the corresponding rotation angle of the winding roller are detected.

[0031] The thickness of the film layer is calculated based on the length of the film layer and the rotation angle of the winding roller.

[0032] In the above technical solution, the thickness of the film layer is calculated by detecting the length of the film layer wound onto the winding roller and the corresponding rotation angle of the winding roller, or by detecting the length of the film layer unwound from the winding roller and the corresponding rotation angle of the winding roller. Therefore, the film layer thickness measurement method of this application has the following advantages: First, in the film layer thickness measurement process, only the length of the film layer and the rotation angle of the winding roller are measured, without the need to squeeze the film layer, so the measurement process is less likely to damage the film layer; Second, the obtained film layer thickness reflects the overall thickness of a section of the film layer, rather than the thickness at a certain position of the film layer, so it has better reference significance for actual production, higher accuracy, and the obtained value can better guide production; Third, the measured length of the film layer and the characteristics of the film layer surface are less correlated, so the measurement process of this application is less affected by ambient light and the surface characteristics of the isolation film, which can effectively reduce measurement errors and improve measurement accuracy.

[0033] In some embodiments, detecting the length of the film layer wound onto the winding roller and the corresponding rotation angle of the winding roller, or detecting the length of the film layer unwound from the winding roller and the corresponding rotation angle of the winding roller, includes:

[0034] During the process of unwinding or rewinding the film layer by the winding roller, the length of the film layer and the corresponding rotation angle of the winding roller are detected multiple times.

[0035] The step of calculating the thickness of the film layer based on the length of the film layer and the rotation angle of the winding roller includes:

[0036] According to the detection time sequence, the rotation angle of the winding roller in the first detection is θ1, and the length of the film layer is L1. The rotation angle of the winding roller in the nth detection is θ. n The length of the film layer is L n , where θ n -θ n-1=2mπ, where m is a positive integer; the obtained data is fitted to obtain a fitting function of the length of the film layer changing with the rotation angle of the winding roller, and the derivative of the fitting function is obtained to obtain a first linear function, the slope of the first linear function being the thickness of the film layer.

[0037] In the above technical solution, it is not necessary to measure or know the initial radius of the winding roller, and the detection process can begin when the film layer has been wound to any number of turns. The method has good flexibility and can be adapted to more application scenarios. By fitting the obtained data to obtain the final film thickness, the influence of measurement error can be effectively reduced, resulting in better accuracy of the obtained film thickness.

[0038] In some embodiments, detecting the length of the film layer wound onto the winding roller and the corresponding rotation angle of the winding roller, or detecting the length of the film layer unwound from the winding roller and the corresponding rotation angle of the winding roller, includes:

[0039] During the process of unwinding or rewinding the film layer by the winding roller, the length of the film layer and the corresponding rotation angle of the winding roller are detected multiple times.

[0040] The step of calculating the thickness of the film layer based on the length of the film layer and the rotation angle of the winding roller includes:

[0041] According to the detection time sequence, the rotation angle of the winding roller in the first detection is θ1, and the length of the film layer is L1. The rotation angle of the winding roller in the nth detection is θ. n The length of the film layer is L n , where θ n -θ n-1 =2mπ, where m is a positive integer;

[0042] Calculate the length increment ΔL of the membrane layer for multiple measurements, ΔL1 = L2 - L1, ΔL n-1 =L n -L n-1 ; Calculate the rotation angle increment Δθ of the winding roller for multiple tests, Δθ1=θ2-θ1, Δθ n-1 =θ n -θ n-1 ;

[0043] The obtained data is fitted to obtain a second linear function that describes the change in the length increment of the film layer as a function of the rotation angle increment of the winding roller, and the slope of the second linear function is the thickness of the film layer.

[0044] In the above technical solution, it is not necessary to measure or know the initial radius of the winding roller, and the detection process can begin when the film layer has been wound to any number of turns. The method has good flexibility and can be adapted to more application scenarios. By fitting the obtained data to obtain the final film thickness, the influence of measurement error can be effectively reduced, resulting in better accuracy of the obtained film thickness.

[0045] In some embodiments, detecting the length of the film layer wound onto the winding roller and the corresponding rotation angle of the winding roller includes:

[0046] During the process of the winding roller winding a complete turn of the film layer, the length of the film layer is detected twice to obtain the length change value ΔD of the film layer, and the rotation angle of the winding roller is detected twice to obtain the rotation angle change value Δα of the winding roller.

[0047] The step of calculating the thickness of the film layer based on the length of the film layer and the rotation angle of the winding roller includes:

[0048] The film thickness t of this turn is calculated using the following formula: ΔD=(r0+(n-1)t)Δα, where r0 is the initial radius of the winding roller and n is the number of turns.

[0049] The thickness of the film layer is calculated over multiple turns. The obtained data is fitted to obtain a constant function of the film layer thickness as a function of the number of turns. The constant value of the constant function is the thickness of the film layer.

[0050] In the above technical solution, directly calculating the film thickness corresponding to multiple turns can easily remove values ​​with large film thickness deviations, reducing the impact of large deviations on the data fitting process. By fitting the obtained data to obtain the final film thickness, the influence of measurement errors can be effectively reduced, resulting in better accuracy of the obtained film thickness.

[0051] Thirdly, embodiments of this application also provide a production line for a single battery cell, including the film thickness measuring device of any of the above embodiments.

[0052] In the above technical solution, the film thickness measuring device is used to measure the thickness of the separator, which can reduce the probability of tab misalignment during the lamination and winding process, improve the yield of battery cell production process, enhance process capability, and reduce production costs. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of the structure of a film thickness measuring device provided in some embodiments of this application;

[0054] Figure 2 Schematic diagrams of the winding mechanism and angle detection device provided in some embodiments of this application;

[0055] Figure 3 Here are exploded views of the battery cell structure in some embodiments of this application;

[0056] Figure 4 This is a cross-sectional view of the electrode assembly in some embodiments of this application;

[0057] Figure 5 This is a structural block diagram of the production line for a single battery cell in some embodiments of this application.

[0058] Figure label:

[0059] 100 film thickness measuring devices; 1000 battery cell production lines;

[0060] Winding mechanism 10;

[0061] 101 winding roller; 102 drive motor; 103 rotating shaft; 104 winding mechanism; 105 unwinding mechanism;

[0062] Detection device 20; roller 201; angle detection device 202;

[0063] Computational unit 30; film layer 40;

[0064] 50 cells per battery.

[0065] Electrode assembly 501; separator 502; base film 5021; coating 5022; housing 503;

[0066] Positive electrode plate 5011; Negative electrode plate 5012;

[0067] Control terminal 60; tension control mechanism 70; roller 80. Detailed Implementation

[0068] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0069] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0070] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0071] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0072] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0073] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0074] In this application, "multiple" means two or more (including two).

[0075] Currently, judging from market trends, the application of power batteries is becoming increasingly widespread. Power batteries are not only used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, but also extensively used in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace. With the continuous expansion of power battery applications, market demand is also constantly increasing.

[0076] You can refer to Figure 3 The battery cell 50 includes a housing 503, electrode components, and an electrolyte. The electrode components include at least one electrode assembly 501. Both the electrode assembly 501 and the electrolyte are housed within the housing 503. (See reference...) Figure 4 The electrode assembly 501 includes a positive electrode 5011, a negative electrode 5012, and a separator 502. The battery cell 50 mainly relies on the movement of metal ions between the positive electrode 5011 and the negative electrode 5012 to operate.

[0077] The positive electrode 5011 includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive current collector, and the positive current collector without the positive active material layer protrudes from the positive current collector with the positive active material layer. The positive current collector without the positive active material layer serves as the positive electrode tab. Taking a lithium-ion battery as an example, the material of the positive current collector can be aluminum, and the positive active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc.

[0078] The negative electrode 5012 includes a negative current collector and a negative active material layer. The negative active material layer is coated on the surface of the negative current collector, and the negative current collector without the negative active material layer protrudes from the negative current collector with the negative active material layer. The negative current collector without the negative active material layer serves as a negative electrode tab. The material of the negative current collector can be copper, and the negative active material can be carbon or silicon, etc. The electrode assembly 501 mentioned in the embodiments of this application can be a wound or stacked structure.

[0079] As a key component of a battery cell, accurately measuring the thickness of the separator is crucial for controlling battery cell production quality and improving battery cell performance. For example, if the separator thickness is not within the preset range, it may cause misalignment of the tabs after the separator is wound into electrode assemblies, or the winding radius of the electrode assemblies may be too large or too small. This can lead to a decrease in the battery cell production process, yield rate, and overall process capability.

[0080] Methods for measuring the thickness of separator films in related technologies include contact and non-contact methods. For example, while contact thickness gauges can measure thickness to a certain extent, they suffer from low measurement efficiency and are prone to damaging the separator film. Non-contact measurement methods, such as optical measurement, can achieve rapid measurement, but are greatly affected by factors such as ambient light and the surface characteristics of the separator film (the separator film surface is usually uneven). Furthermore, the separator film is usually thin, resulting in larger measurement errors and limited measurement accuracy.

[0081] To address the aforementioned technical problems, this application proposes a film thickness measuring device capable of measuring the thickness of a release liner. The film thickness measuring device includes a detection unit that detects the length of the film layer wound onto the winding roller and the corresponding rotation angle of the winding roller; or, the detection unit detects the length of the film layer unwound from the winding roller and the corresponding rotation angle of the winding roller; then, a calculation unit calculates the film thickness based on the film layer length and the rotation angle of the winding roller.

[0082] Therefore, the film thickness measuring device of this application has the following advantages: First, the film layer does not need to be squeezed during the film thickness measurement process, so the film layer is not easily damaged during the measurement process; Second, the obtained film thickness reflects the overall thickness of a section of the film layer, rather than the thickness at a certain location of the film layer, so it has better reference significance for actual production, higher accuracy, and the obtained values ​​can better guide production; Third, the measured length of the film layer is less correlated with the characteristics of the film layer surface, so the measurement process of this application is less affected by ambient light and the surface characteristics of the isolation film, and the measurement accuracy is better.

[0083] The film thickness measuring device disclosed in this application can be used not only to measure the thickness of the separator, but also to measure the thickness of the current collector and the electrode. In some embodiments, the separator includes a base film and a coating layer disposed on the surface of the base film. The film thickness measuring device disclosed in this application can also be used to measure the thickness of the base film.

[0084] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.

[0085] Figure 1 This is a schematic diagram of the structure of a film thickness measuring device 100 provided in some embodiments of this application. The film thickness measuring device 100 includes a winding mechanism 10, a detection device 20, and a calculation unit 30.

[0086] In some embodiments, the winding mechanism 10 includes a winding roller 101 for winding the film layer 40; the detection device 20 is used to detect the length of the film layer 40 wound onto the winding roller 101 and the corresponding rotation angle of the winding roller 101; for example, relative to the initial detection position, the length of the film layer 40 wound onto the winding roller 101 is L, and the corresponding rotation angle of the winding roller 101 refers to the total rotation angle of the winding roller 101 during the process of winding the film layer 40 of length L. The calculation unit 30 is configured to obtain the thickness of the film layer 40 based on the length of the film layer 40 wound onto the winding roller 101 and the corresponding rotation angle of the winding roller 101.

[0087] In some embodiments, the winding mechanism 10 includes a winding roller 101 for winding the film layer 40; the detection device 20 is used to detect the length of the film layer 40 unwound from the winding roller 101 and the corresponding rotation angle of the winding roller 101; for example, the length of the film layer 40 unwound from the winding roller 101 relative to the initial detection position is L, and the corresponding rotation angle of the winding roller 101 refers to the total rotation angle of the winding roller 101 during the process of unwinding the film layer 40 of length L. The calculation unit 30 is configured to obtain the thickness of the film layer 40 based on the length of the film layer 40 unwound from the winding roller 101 and the corresponding rotation angle of the winding roller 101.

[0088] In other words, the winding roller 101 in this application can be either a winding roller for winding up the film layer 40 or an unwinding roller for unwinding the film layer 40.

[0089] Here, the detection device 20 may include a length detection device and an angle detection device 202. The length detection device is used to detect the length of the film layer 40, and the angle detection device 202 is used to detect the rotation angle of the winding roller 101.

[0090] For example, the length detection device can be a roller-type length measuring instrument. The film layer 40 is supported on the roller 201 of the roller-type length measuring instrument. The movement of the film layer 40 drives the roller 201 to rotate, so that the length of the film layer 40 can be calculated using the circumference and rotation angle of the roller 201.

[0091] For example, the length detection device can also be a laser displacement sensor, which scans the surface of the film layer 40 and calculates the length by integrating the displacement change. For example, the length detection device can also be an ultrasonic sensor, which measures the time difference of the reflected signal when the film layer 40 moves. For example, the length measurement device can also be a camera, which captures the texture on the film layer 40 and calculates the displacement using an image algorithm.

[0092] For example, the angle detection device 202 can be an encoder, a combination of a Hall sensor and a magnet, or a combination of a photoelectric sensor and an encoder disk. The angle detection device 202 can be disposed on the winding roller 101 or on the rotating shaft 103 connected to the winding roller 101.

[0093] It should be noted that, in the ideal case where the thickness of the film layer 40 is uniform everywhere, during the unwinding or rewinding process of the film layer 40, each time a layer of film layer 40 is added or removed from the winding roller 101, the overall radius of the winding roller 101 with the film layer 40 wound on it decreases or increases by the thickness of one layer of film layer 40. Correspondingly, the length of each turn of film layer 40 also gradually decreases or increases, and the difference in length between adjacent turns of film layer 40 wound at the same rotation angle is equal. The ratio of the difference in length between adjacent turns of film layer 40 to the rotation angle of the winding roller 101 corresponding to each detection position is the thickness of the film layer 40. Based on the above principle, the calculation unit 30 can calculate the thickness of the film layer 40 based on the detected lengths of multiple film layers 40 and the corresponding rotation angles of multiple winding rollers 101.

[0094] In the film thickness measuring device 100 with the above-described structure, the thickness of the film layer 40 is calculated by detecting the length of the film layer 40 wound onto the winding roller 101 and the corresponding rotation angle of the winding roller 101, or by detecting the length of the film layer 40 unwound from the winding roller 101 and the corresponding rotation angle of the winding roller 101. Therefore, the film thickness measuring device 100 of this application has the following advantages: First, in the process of measuring the thickness of the film layer 40, only the length of the film layer 40 and the rotation angle of the winding roller 101 are measured, without the need to squeeze the film layer 40, so the measurement process is less likely to damage the film layer 40; Second, the obtained thickness of the film layer 40 reflects the overall thickness of a section of the film layer 40, rather than the thickness at a certain position of the film layer 40, so it has better reference significance for actual production, higher accuracy, and the obtained value can better guide production; Third, the measured length of the film layer 40 has little correlation with the surface characteristics of the film layer 40, so the measurement process of this application is less affected by ambient light and the surface characteristics of the isolation film 502, and the measurement accuracy is better.

[0095] In some embodiments, reference may be made to Figure 3 and Figure 4 The membrane 40 is the separator 502 of the battery cell 50, which is used to separate the positive electrode 5011 and the negative electrode 5012 of the battery cell 50.

[0096] For example, the battery cell production line 1000 may include a production line for separator 502. The separator 502 production line may include a slitting and winding process for slitting and then winding the separator 502. The film thickness measuring device 100 is used to measure the thickness of the slitting and winding separator 502 to monitor the thickness of the produced separator 502 and adjust the production parameters of the separator 502 production line in a timely manner. For example, the thickness of the base film 5021, the processing parameters of the base film 5021, the thickness of the coating layer 5022 on the surface of the base film 5021, etc. At the same time, separators 502 that do not meet the thickness requirements will not directly enter the next process, thereby improving product quality. Alternatively, separators 502 with abnormal thickness can be specially treated, such as being individually marked and shipped for use in combination with other thicknesses.

[0097] The separator membrane is thin and has an uneven surface. Conventional optical measurement methods are highly susceptible to the surface characteristics of the separator membrane, resulting in poor accuracy and making it unsuitable for predicting the position of tabs in electrode assemblies. Contact measurement methods, on the other hand, are prone to damaging the separator membrane. In contrast, the membrane thickness measuring device 100 of this application is less affected by the characteristics of the separator membrane 502 itself, adapting well to its inherent properties and achieving higher accuracy and precision. Compared to traditional manual sampling measurements, this application allows for separator membrane 502 thickness detection without interrupting production, significantly improving production efficiency and reducing costs.

[0098] For example, the battery cell production line 1000 includes a stacking and winding process for stacking and winding the positive electrode 5011, the negative electrode 5012, and the separator 502 together. The stacking and winding process includes a film thickness measuring device 100, which is used to separately wind the separator 502 before winding it together with the positive electrode 5011 and the negative electrode 5012 to measure the thickness of the separator 502. When excessive fluctuations in the thickness of the separator 502 are detected, potentially leading to electrode misalignment, an early warning can be issued. Therefore, the film thickness measuring device of this application, used to measure the thickness of the separator 502, can reduce the probability of electrode misalignment during the stacking and winding process, improve the yield rate of the battery cell 50 production process, enhance process capability, and reduce production costs.

[0099] In some embodiments, the film layer 40 is the base film 5021 of the separator 502 of the battery cell 50, and the separator 502 is used to separate the positive electrode and the negative electrode of the battery cell 50. The battery cell 50 includes an electrode assembly 501, the electrode assembly 501 includes a separator 502, the separator 502 includes a base film 5021 and a coating 5022 disposed on the base film 5021, and the film layer 40 is the base film 5021.

[0100] For example, the base film 5021 can be a polyethylene film (PE), a polypropylene film (PP), a PP / PE / PP multilayer composite film, a polyethylene terephthalate film (PET), or a polyimide film (PI), etc. The coating 5022 can be a sprayed coating, which can be a ceramic particle sprayed coating or a fluorine-containing compound sprayed coating, etc.

[0101] Since the thickness of the base film 5021 is smaller, a small measurement error can greatly affect the measurement result when the thickness of the base film 5021 is measured directly. The thickness of the base film 5021 is measured by the film thickness measuring device 100 of this application. The thickness of the base film 5021 is calculated by measuring the length of the base film 5021 and the rotation angle of the corresponding winding roller 101. The length of the base film 5021 and the rotation angle of the winding roller 101 are relatively large, so the influence of the measurement error of the detection device 20 on the measurement of the thickness of the base film 5021 can be reduced, making the measured thickness result of the base film 5021 more accurate.

[0102] In some embodiments, reference may be made to Figure 1 The film thickness measuring device 100 also includes a control terminal 60, which is configured to determine whether the thickness of the film 40 is within a preset range and provide a prompt.

[0103] The system can provide a prompt only when the thickness of film layer 40 is outside the preset range. Alternatively, it can provide one prompt when the thickness of film layer 40 is within the preset range and another prompt when the thickness of film layer 40 is outside the preset range. The prompt can be an audible prompt, a visual prompt, or the thickness of film layer 40 can be displayed on the display terminal. When the thickness of film layer 40 is outside the preset range, a pop-up prompt can be provided; no specific restrictions are imposed here.

[0104] By providing prompts, users can promptly obtain information about the thickness of the film layer 40 without manual monitoring, which helps to improve the automation level of the film thickness measurement device 100.

[0105] In some embodiments, reference may be made to Figure 1The detection device 20 includes a roller 201, which is rotatable. The film layer 40 is supported on the roller 201. The detection device 20 is constructed such that the length of the film layer 40 is calculated based on the circumference of the roller 201 and the number of rotations.

[0106] For example, the roller 201 can be disposed among multiple guide rollers 80 and spaced apart from the winding mechanism 10. During the winding or unwinding process of the film layer 40, the film layer 40 will continuously wind onto the winding roller 101 or continuously leave the winding roller 101. The moving film layer 40 is supported on the roller 201, which will drive the roller 201 to rotate. The length of the film layer 40 can then be calculated from the circumference of the roller 201 and the number of rotations.

[0107] The circumference of roller 201 can be precisely calibrated, for example, by using a laser measuring device to measure the circumference of roller 201, ensuring that the length measurement error is within ±0.1 mm.

[0108] The length of the film layer 40 is calculated based on the circumference and number of rotations of the roller 201. The accuracy of the detection results is high and less affected by the surface characteristics of the film layer 40.

[0109] In some embodiments, reference may be made to Figure 1 The film thickness measuring device 100 also includes a tension control mechanism 70, which is spaced apart from the winding mechanism 10. The film 40 is supported by the tension control mechanism 70, which is used to control the tension of the film 40 within a set range.

[0110] For example, the tension control mechanism 70 is installed on the movement path of the film layer 40 to control the tension fluctuation of the film layer 40 within a set fluctuation range of 5%. Specifically, the tension control mechanism 70 can be a buoyancy roller, which detects tension changes and dynamically adjusts the winding mechanism 10 in conjunction with the controller.

[0111] By setting the tension control mechanism 70 to control the tension of the film layer 40, on the one hand, it is beneficial to smoothly wind up or unwind the film layer 40; on the other hand, it is beneficial to improve the accuracy of the measured length of the film layer 40.

[0112] In some embodiments, the setting range is 60 kgf to 500 kgf.

[0113] For example, the production line for the separator film 502 may include a slitting and winding process. The slitting and winding process is used to slit and then wind the separator film 502. In this process, the set range can be 300 kgf to 500 kgf. In this way, the tension on the film layer 40 will not be too small, and the separator film 502 will not easily slip or shift during transportation after winding, resulting in uneven edges. The tension on the separator film 502 will also not be too large, which would cause the separator film 502 to have scratches or breakage.

[0114] For example, the battery cell production line 1000 includes a stacking and winding process, which is used to stack and wind the positive electrode 5011, the negative electrode 5012 and the separator 502 together. The stacking and winding process includes a film thickness measuring device 100, the set range of which is 60 kgf to 250 kgf. In this way, the tension of the separator 502 will not be too high, which would cause the electrode assembly to wrinkle, nor will the tension of the separator 502 be too low, which would cause the electrode assembly 501 to be too loose, which would increase the risk of internal short circuit.

[0115] Furthermore, it also facilitates accurate measurement of the thickness of the 502 separator membrane. Depending on the actual situation, a more suitable range can be selected.

[0116] In some embodiments, reference may be made to Figure 2 The detection device 20 includes an angle detection device 202, and the winding mechanism 10 includes a drive motor 102. The rotation shaft 103 of the drive motor 102 is connected to the winding roller 101 to drive the winding roller 101 to rotate. The angle detection device 202 is located on the rotation shaft 103 of the drive motor 102 and is used to detect the rotation angle of the winding roller 101.

[0117] By setting the angle detection device 202 on the rotating shaft 103 of the drive motor 102, the position of the angle detection device 202 can be moved when the winding roller 101 is removed, and the angle detection device 202 does not need to be repeatedly disassembled and installed, making it more convenient to use and reducing the cost of use.

[0118] For example, in some other embodiments, the angle detection device 202 may be directly disposed on the winding roller 101, or the sensing element may be disposed only on the winding roller 101. The angle detection device 202 may also be disposed at equal intervals from the winding roller 101 and the rotating shaft 103. The angle detection device 202 determines the angle change of the winding roller 101 by detecting the position change of the sensing element, so as to realize the detection of the rotation angle of the winding roller 101.

[0119] In some embodiments, reference may be made to Figure 1The film thickness measuring device 100 also includes a guide roller 80, which is spaced apart from the winding roller 101. The guide roller 80 is rotatable and supports the film layer 40. The guide roller 80 can also be called a guide roller or transition roller. Multiple guide rollers 80 can be provided as needed; for example, refer to... Figure 1 The winding mechanism 10 includes a winding mechanism 104 and an unwinding mechanism 105. The winding mechanism 104 is used to wind up the film layer 40, and the unwinding mechanism 105 is used to unwind the film layer 40. A guide roller 80 is provided on the downstream side of the unwinding mechanism 105, and a guide roller 80 is provided on the upstream side of the winding mechanism 104. Guide rollers 80 can be provided on both the upstream and downstream sides of the roller 201, and guide rollers 80 can be provided on both the upstream and downstream sides of the tension control mechanism 70. Through the multi-roller layout, the internal stress of the film layer 40 can be eliminated, and the interlayer tightness and uniformity of the film layer 40 after winding can be improved.

[0120] By setting the guide roller 80 to support the film layer 40 moving along the set path, the guide roller 80 can absorb system vibration and reduce the shaking of the film layer 40 when it moves at high speed. At the same time, it is also used to guide the film layer 40 to move along the set path and reduce deviation or twisting.

[0121] In some embodiments, the detection device 20 is configured to: repeatedly detect the length of the film layer 40 and the corresponding rotation angle of the winding roller 101 during the unwinding or rewinding of the film layer 40 by the winding roller 101; according to the detection time sequence, the rotation angle of the winding roller 101 detected for the first time is θ1, the length of the film layer 40 is L1, and the rotation angle of the winding roller 101 detected for the nth time is θ1. n The length of the film layer 40 is L n , where θ n -θ n-1 =2mπ, where m is a positive integer; the calculation unit 30 is constructed to: fit the obtained data to obtain a fitting function of the length of the film layer 40 changing with the rotation angle of the winding roller 101, and differentiate the fitting function to obtain a first linear function, the slope of the first linear function being the thickness of the film layer 40.

[0122] The difference in rotation angle between the winding roller 101 in adjacent detection cycles can be equal or unequal. For example, θ1 = π, θ2 = 3π, θ3 = 5π, θ4 = 7π, ..., θ n =(2n-1)π, n is a positive integer. For example, θ1=π, θ2=3π, θ3=7π, θ4=13π,…, θ n = 2mπ + π, where m is a natural number.

[0123] In the above technical solution, it is not necessary to measure or know the initial radius of the winding roller 101, and the detection process can begin when the film layer 40 has been wound to any number of turns. The method has good flexibility and can be adapted to more application scenarios. By fitting the obtained data to obtain the final thickness of the film layer 40, the influence of measurement error can be effectively reduced, resulting in better accuracy of the obtained film layer thickness.

[0124] In some embodiments, the detection device 20 is configured to: repeatedly detect the length of the film layer 40 and the corresponding rotation angle of the winding roller 101 during the unwinding or rewinding of the film layer 40 by the winding roller 101; according to the detection time sequence, the rotation angle of the winding roller 101 detected for the first time is θ1, the length of the film layer 40 is L1, and the rotation angle of the winding roller 101 detected for the nth time is θ1. n The length of the film layer 40 is L n , where θ n -θ n-1 =2mπ, where m is a positive integer;

[0125] The calculation unit 30 is configured to calculate the length increment ΔL of the membrane layer 40 after multiple detections, where ΔL1 = L2 - L1, ΔL n-1 =L n -L n-1 ; Calculate the rotation angle increment Δθ of the winding roller for multiple tests, Δθ1=θ2-θ1, Δθ n-1 =θ n -θ n-1 The obtained data is fitted to obtain a second linear function that changes the length increment of the film layer 40 with the rotation angle increment of the winding roller 101. The slope of the second linear function is the thickness of the film layer 40.

[0126] The difference in rotation angle between the winding roller 101 in adjacent detection cycles can be equal or unequal. For example, θ1 = π, θ2 = 3π, θ3 = 5π, θ4 = 7π, ..., θ n =(2n-1)π, n is a positive integer. For example, θ1=π, θ2=3π, θ3=7π, θ4=13π,…, θ n =2mπ + π, where m is a positive integer.

[0127] In the above technical solution, it is not necessary to measure or know the initial radius of the winding roller 101, and the detection process can begin when the film layer 40 has been wound to any number of turns. The method has good flexibility and can be adapted to more application scenarios. By fitting the obtained data to obtain the final thickness of the film layer 40, the influence of measurement error can be effectively reduced, resulting in better accuracy of the obtained thickness of the film layer 40.

[0128] In some embodiments, the detection device 20 is configured to: detect the length of the film layer 40 twice to obtain the length change value ΔD of the film layer 40 during the process of the winding roller 101 winding a complete turn of the film layer 40, and detect the rotation angle of the winding roller 101 twice to obtain the rotation angle change value Δα of the winding roller 101.

[0129] The calculation unit 30 is configured to calculate the thickness t of the film layer 40 in this loop using the following formula: ΔD=(r0+(n-1)t)Δα, where r0 is the initial radius of the winding roller 101, and n is the number of loops. Here, the number of loops can be calculated by the rotation angle of the winding roller 101. For example, a rotation angle less than 2π indicates the first loop, a rotation angle greater than 2π but less than 4π indicates the second loop, and so on. For the x-th loop, Δα... x =α2-α1, for the y-th cycle, Δα y = α4 - α3, where Δα x and Δα y They can be equal or unequal; α⁴ - α² can be equal to 2mπ or not. 3- α1 can be equal to 2mπ or not, where m is a positive integer. However, the sampling positions of α2 and α1 need to be on the same circle, and the sampling positions of α4 and α3 need to be on the same circle, so that the rotation radii at the two sampling positions are theoretically equal.

[0130] The thickness of the membrane layer 40 across multiple turns is calculated. The obtained data is then fitted to obtain a constant function representing the change in membrane layer 40 thickness with the number of turns. The constant value of this constant function is the thickness of membrane layer 40. The membrane layer thickness can be calculated for multiple turns, for example, the first turn, the third turn, and the (2n-1)th turn; alternatively, different turns can be randomly selected to calculate the membrane layer thickness for each turn.

[0131] Directly calculating the thickness of film layer 40 corresponding to multiple turns can easily remove values ​​with large deviations in film layer 40 thickness, reducing the impact of large deviations on the data fitting process. By fitting the obtained data to obtain the final thickness of film layer 40, the influence of measurement errors can be effectively reduced, resulting in better accuracy of the obtained film layer 40 thickness.

[0132] A second aspect of this application also proposes a method for measuring film thickness, which employs the film thickness measuring device 100 described in the above embodiments.

[0133] In some embodiments, the film thickness measurement method includes: detecting the length of the film 40 wound onto the winding roller 101 and the corresponding rotation angle of the winding roller 101; and calculating the thickness of the film 40 based on the length of the film 40 and the rotation angle.

[0134] In some embodiments, the film thickness measurement method includes: detecting the length of the film 40 unwound from the winding roller 101 and the corresponding rotation angle of the winding roller 101; and calculating the thickness of the film 40 based on the length of the film 40 and the rotation angle of the winding roller 101.

[0135] The aforementioned film thickness measurement method calculates the thickness of the film layer 40 by detecting the length of the film layer 40 wound onto the winding roller 101 and the corresponding rotation angle of the winding roller 101, or by detecting the length of the film layer 40 unwound from the winding roller 101 and the corresponding rotation angle of the winding roller 101. Therefore, the film thickness measurement method of this application has the following advantages: First, during the film layer 40 thickness measurement process, only the length of the film layer 40 and the rotation angle of the winding roller 101 are measured, without needing to squeeze the film layer 40, thus the measurement process is less likely to damage the film layer 40; Second, the obtained film layer 40 thickness reflects the overall thickness of a section of the film layer 40, rather than the thickness at a certain location of the film layer 40, thus providing better reference for actual production, higher accuracy, and the obtained values ​​can better guide production; Third, the measured length of the film layer 40 has little correlation with the surface characteristics of the film layer 40, therefore, the measurement process of this application is less affected by ambient light and the surface characteristics of the separator 502, effectively reducing measurement errors and improving measurement precision and accuracy.

[0136] It should be noted that, in the ideal case where the thickness of the film layer 40 is equal everywhere, during the unwinding or rewinding of the film layer 40, each time a layer of film layer 40 is reduced or added on the winding roller 101, the overall radius of the winding roller 101 with the film layer 40 wound on it will decrease or increase by the thickness of one layer of film layer 40. Correspondingly, the length of each turn of film layer 40 will also gradually decrease or increase, and the difference in length between adjacent turns of film layer 40 wound at the same rotation angle is equal. The ratio of the difference in length between adjacent turns of film layer 40 to the rotation angle of the winding roller 101 corresponding to each detection position is the thickness of the film layer 40.

[0137] Based on the above principle, more specifically, detecting the length of the film layer 40 wound onto the winding roller 101 and the corresponding rotation angle of the winding roller 101, or detecting the length of the film layer 40 unwound from the winding roller 101 and the corresponding rotation angle of the winding roller 101, includes:

[0138] During the process of unwinding or rewinding the film layer 40 by the winding roller 101, the length of the film layer 40 and the corresponding rotation angle of the winding roller 101 are detected multiple times.

[0139] The thickness of the film layer 40 is calculated based on the length of the film layer 40 and the rotation angle of the winding roller 101, including:

[0140] According to the detection time sequence, the rotation angle of the winding roller 101 in the first detection is θ1, and the length of the film layer 40 is L1. The rotation angle of the winding roller 101 in the nth detection is θ1. n The length of the film layer 40 is L n , where θ n -θ n-1 =2mπ, where m is a positive integer.

[0141] A mathematical algorithm is used to fit the obtained data to obtain a fitting function of the length of the film layer 40 changing with the rotation angle of the winding roller 101. The derivative of the fitting function is used to obtain the first linear function, and the slope of the first linear function is the thickness of the film layer 40.

[0142] The difference in rotation angle between the winding roller 101 in adjacent detection cycles can be equal or unequal. For example, θ1 = π, θ2 = 3π, θ3 = 5π, θ4 = 7π, ..., θ n =(2n-1)π, n is a positive integer. For example, θ1=π, θ2=3π, θ3=7π, θ4=13π,…, θ n = 2mπ + π, where m is a natural number.

[0143] In the above technical solution, it is not necessary to measure or know the initial radius of the winding roller 101, and the detection process can begin when the film layer 40 has been wound to any number of turns. The method has good flexibility and can be adapted to more application scenarios. By fitting the obtained data to obtain the final thickness of the film layer 40, the influence of measurement error can be effectively reduced, resulting in better accuracy of the obtained film layer thickness.

[0144] Based on the above principle, more specifically, detecting the length of the film layer 40 wound onto the winding roller 101 and the corresponding rotation angle of the winding roller 101, or detecting the length of the film layer 40 unwound from the winding roller 101 and the corresponding rotation angle of the winding roller 101, includes:

[0145] During the process of unwinding or rewinding the film layer 40 by the winding roller 101, the length of the film layer 40 and the corresponding rotation angle of the winding roller 101 are detected multiple times.

[0146] The calculation of the thickness of the film layer 40 based on the length of the film layer 40 and the rotation angle of the winding roller 101 includes: according to the detection time sequence, the rotation angle of the winding roller 101 in the first detection is θ1, the length of the film layer 40 is L1, and the rotation angle of the winding roller 101 in the nth detection is θ1. n The length of the film layer 40 is L n , where θ n -θ n-1=2mπ, where m is a positive integer; calculate the length increment ΔL of the membrane layer 40 after multiple tests, ΔL1 = L2 - L1, ΔL n-1 =L n -L n-1 ; Calculate the rotation angle increment Δθ of the winding roller for multiple tests, Δθ1=θ2-θ1, Δθ n-1 =θ n -θ n-1 .

[0147] The obtained data is fitted using a mathematical algorithm to obtain a second linear function that changes the length increment ΔL of the film layer 40 with the rotation angle increment Δθ of the winding roller 101. The slope of the second linear function is the thickness of the film layer 40.

[0148] The difference in rotation angle between the winding roller 101 in adjacent detection cycles can be equal or unequal. For example, θ1 = π, θ2 = 3π, θ3 = 5π, θ4 = 7π, ..., θ n =(2n-1)π, n is a positive integer. For example, θ1=π, θ2=3π, θ3=7π, θ4=13π,…, θ n =2mπ + π, where m is a positive integer.

[0149] In the above technical solution, it is not necessary to measure or know the initial radius of the winding roller 101, and the detection process can begin when the film layer 40 has been wound to any number of turns. The method has good flexibility and can be adapted to more application scenarios. By fitting the obtained data to obtain the final thickness of the film layer 40, the influence of measurement error can be effectively reduced, resulting in better accuracy of the obtained thickness of the film layer 40.

[0150] Based on the above principle, more specifically, detecting the length of the film layer 40 wound onto the winding roller 101 and the corresponding rotation angle of the winding roller 101 includes:

[0151] During the process of winding one complete turn of the film layer 40 by the winding roller 101, the length of the film layer 40 is measured twice to obtain the length change value ΔD of the film layer 40, and the rotation angle of the winding roller 101 is measured twice to obtain the rotation angle change value Δα of the winding roller 101. The method of this embodiment is generally used in scenarios where the winding roller 101 is used to wind the film layer 40, so as to easily determine the number of turns where the detection position is located. Here, before winding, one end of the film layer 40 needs to be fixed flat on the winding roller 101 to ensure that the film layer 40 and the winding roller 101 are tightly attached without wrinkles or misalignment.

[0152] The thickness of film layer 40 is calculated based on the length of film layer 40 and the rotation angle of winding roller 101, including: calculating the thickness t of film layer 40 for that turn using the following formula: ΔD=(r0+(n-1)t)Δα, where r0 is the initial radius of winding roller 101 and n is the number of turns; here, the number of turns can be calculated by the rotation angle of winding roller 101. For example, a rotation angle less than 2π is the first turn, a rotation angle greater than 2π but less than 4π is the second turn, and so on. For the x-th turn, Δα x =α2-α1, for the y-th cycle, Δα y = α4 - α3, where Δα x and Δα y They can be equal or unequal; α⁴ - α² can be equal to 2mπ or not. 3- α1 can be equal to 2mπ or not, where m is a positive integer. However, the sampling positions of α2 and α1 need to be on the same circle, and the sampling positions of α4 and α3 need to be on the same circle, so that the rotation radii at the two sampling positions are theoretically equal.

[0153] The thickness of the multi-turn membrane layer 40 is calculated by fitting the obtained data using a mathematical algorithm to obtain a constant function of the membrane layer 40 thickness as a function of the number of turns. The constant value of the constant function is the thickness of the membrane layer 40. The membrane layer thickness can be calculated for multiple turns, for example, the thickness of the first turn, the third turn, and the (2n-1)th turn; or, different turns can be randomly selected to calculate the membrane layer thickness for that turn.

[0154] Directly calculating the thickness of film layer 40 corresponding to multiple turns can easily remove values ​​with large deviations in film layer 40 thickness, reducing the impact of large deviations on the data fitting process. By fitting the obtained data to obtain the final thickness of film layer 40, the influence of measurement errors can be effectively reduced, resulting in better accuracy of the obtained film layer 40 thickness.

[0155] In some embodiments, the mathematical algorithm is the least squares method. The least squares method can be linear or nonlinear, and the choice can be made based on the data used. Using the least squares method to fit the data is particularly effective when the length increment ΔL of the film layer 40 exhibits a strong linear relationship with the rotation angle increment Δθ of the winding roller 101. This method offers high accuracy and computational efficiency.

[0156] For example, the specific calculation process of the second linear function that uses the least squares method to fit the length increment ΔL of the film layer 40 as a function of the rotation angle increment Δθ of the winding roller 101 is as follows:

[0157] Assume the fitted model is: f(Δθ) = kΔθ + b;

[0158] For n sets of detection data (Δθ) i ΔL i If we fit these data using the function f(Δθ), then the sum of squared errors is:

[0159]

[0160] By taking the partial derivatives of S with respect to a and b respectively, and setting the partial derivatives to zero, we can obtain the normal equation system:

[0161]

[0162]

[0163] After simplification, we obtain the following system of linear equations:

[0164]

[0165] Solving the above system of linear equations will yield the slope k and the intercept b.

[0166] In other embodiments, the mathematical algorithm may also employ other more suitable algorithms, such as robust regression algorithms, nonlinear least squares methods, etc., depending on the circumstances.

[0167] like Figure 5 As shown, the third aspect of this application also proposes a production line 1000 for a single battery cell.

[0168] like Figure 5 As shown, the production line 1000 for this battery cell includes the film thickness measuring device 100 of the above-described embodiments.

[0169] For example, the battery cell production line 1000 includes a separator 502 production line, which includes the film thickness measuring device 100 of the above embodiments.

[0170] For example, the battery cell production line 1000 includes a stacking and winding process for stacking and winding the positive electrode 5011, the negative electrode 5012 and the separator 502 together. The stacking and winding process includes a film thickness measuring device 100 for measuring the thickness of the separator 502 before it is wound together with the positive electrode 5011 and the negative electrode 5012.

[0171] In some embodiments, the production line 1000 for a single battery cell may include a control terminal 60, which is connected to the detection device 20 via wired or wireless means to ensure the stability and timeliness of data transmission.

[0172] The battery cell production line 1000 is also equipped with other production and testing equipment, such as winding equipment, welding equipment, and insulation performance testing equipment.

[0173] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0174] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A film thickness measuring device, characterized in that, The film layer is used in a single battery cell and includes: A winding mechanism, the winding mechanism including a winding roller for winding the film layer; A detection device is used to detect the length of the film layer wound onto the winding roller and the corresponding rotation angle of the winding roller; or, the detection device is used to detect the length of the film layer unwound from the winding roller and the corresponding rotation angle of the winding roller. A calculation unit is configured to obtain the thickness of the film layer based on the length of the film layer and the rotation angle of the winding roller.

2. The film thickness measuring device as described in claim 1, characterized in that, The membrane is the separator of the battery cell, and the separator is used to separate the positive electrode and the negative electrode of the battery cell.

3. The film thickness measuring device as described in claim 1 or 2, characterized in that, The film layer is the base film of the separator of the battery cell, and the separator is used to separate the positive electrode and the negative electrode of the battery cell.

4. The film thickness measuring device according to any one of claims 1-3, characterized in that, It also includes a control terminal, which is configured to determine whether the thickness of the film layer is within a preset range and provide a prompt.

5. The film thickness measuring device according to any one of claims 1-4, characterized in that, The detection device includes a roller that is rotatable, and the film layer is supported on the roller. The detection device is configured to calculate the length of the film layer based on the circumference of the roller and the number of rotations.

6. The film thickness measuring device according to any one of claims 1-5, characterized in that, It also includes a tension control mechanism, which is spaced apart from the winding mechanism. The film layer is supported by the tension control mechanism, which is used to control the tension of the film layer within a set range.

7. The film thickness measuring device as described in claim 6, characterized in that, The set range is 60 kgf to 500 kgf.

8. The film thickness measuring device according to any one of claims 1-7, characterized in that, The detection device includes an angle detection device, the winding mechanism includes a drive motor, the rotation shaft of the drive motor is connected to the winding roller to drive the winding roller to rotate, and the angle detection device is located on the rotation shaft of the drive motor to detect the rotation angle of the winding roller.

9. The film thickness measuring device according to any one of claims 1-8, characterized in that, It also includes a guide roller, which is arranged spaced apart from the winding roller, and the guide roller is rotatable and used to support the film layer.

10. The film thickness measuring device according to any one of claims 1-9, characterized in that, The detection device is configured to detect the length of the film layer and the corresponding rotation angle of the winding roller multiple times during the process of unwinding or rewinding the film layer by the winding roller. According to the detection time sequence, the rotation angle of the winding roller in the first detection is θ1, and the length of the film layer is L1. The rotation angle of the winding roller in the nth detection is θ. n The length of the film layer is L n , where θ n -θ n-1 =2mπ, where m is a positive integer; The calculation unit is configured to: fit the obtained data to obtain a fitting function of the length of the film layer changing with the rotation angle of the winding roller, and differentiate the fitting function to obtain a first linear function, the slope of the first linear function being the thickness of the film layer.

11. The film thickness measuring device according to any one of claims 1-9, characterized in that, The detection device is configured to detect the length of the film layer and the corresponding rotation angle of the winding roller multiple times during the process of unwinding or rewinding the film layer by the winding roller. According to the detection time sequence, the rotation angle of the winding roller in the first detection is θ1, and the length of the film layer is L1. The rotation angle of the winding roller in the nth detection is θ. n The length of the film layer is L n , where θ n -θ n-1 =2mπ, where m is a positive integer; The calculation unit is configured to calculate the length increment ΔL of the membrane layer after multiple detections, where ΔL1 = L2 - L1, ΔL n-1 =L n -L n-1 ; Calculate the rotation angle increment Δθ of the winding roller for multiple tests, Δθ1=θ2-θ1, Δθ n-1 =θ n -θ n-1 The obtained data is fitted to obtain a second linear function that describes the change in the length increment of the film layer as a function of the rotation angle increment of the winding roller, and the slope of the second linear function is the thickness of the film layer.

12. The film thickness measuring device according to any one of claims 1-9, characterized in that, The detection device is configured to: detect the length of the film layer twice during the process of the winding roller winding a complete turn of the film layer to obtain the length change value ΔD of the film layer, and detect the rotation angle of the winding roller twice to obtain the rotation angle change value Δα of the winding roller. The calculation unit is configured to: calculate the film thickness t of the turn using the following formula: ΔD=(r0+(n-1)t)Δα, where r0 is the initial radius of the winding roller and n is the number of turns; calculate the film thickness of multiple turns, fit the obtained data to obtain a constant function of the film thickness changing with the number of turns, and the constant value of the constant function is the thickness of the film.

13. A method for measuring film thickness, characterized in that, The film thickness measurement method, using the film thickness measuring device according to any one of claims 1-12, comprises: The length of the film layer wound onto the winding roller and the corresponding rotation angle of the winding roller are detected, or the length of the film layer unwound from the winding roller and the corresponding rotation angle of the winding roller are detected. The thickness of the film layer is calculated based on the length of the film layer and the rotation angle of the winding roller.

14. The film thickness measurement method as described in claim 13, characterized in that, The detection of the length of the film layer wound onto the winding roller and the corresponding rotation angle of the winding roller, or the detection of the length of the film layer unwound from the winding roller and the corresponding rotation angle of the winding roller, includes: During the process of unwinding or rewinding the film layer by the winding roller, the length of the film layer and the corresponding rotation angle of the winding roller are detected multiple times. The step of calculating the thickness of the film layer based on the length of the film layer and the rotation angle of the winding roller includes: According to the detection time sequence, the rotation angle of the winding roller in the first detection is θ1, and the length of the film layer is L1. The rotation angle of the winding roller in the nth detection is θ. n The length of the film layer is L n , where θ n -θ n-1 =2mπ, where m is a positive integer; The obtained data is fitted to obtain a fitting function of the length of the film layer as a function of the rotation angle of the winding roller. The derivative of the fitting function is obtained to obtain a first linear function, the slope of which is the thickness of the film layer.

15. The film thickness measurement method as described in claim 13, characterized in that, The detection of the length of the film layer wound onto the winding roller and the corresponding rotation angle of the winding roller, or the detection of the length of the film layer unwound from the winding roller and the corresponding rotation angle of the winding roller, includes: During the process of unwinding or rewinding the film layer by the winding roller, the length of the film layer and the corresponding rotation angle of the winding roller are detected multiple times. The step of calculating the thickness of the film layer based on the length of the film layer and the rotation angle of the winding roller includes: According to the detection time sequence, the rotation angle of the winding roller in the first detection is θ1, and the length of the film layer is L1. The rotation angle of the winding roller in the nth detection is θ. n The length of the film layer is L n , where θ n -θ n-1 =2mπ, where m is a positive integer; Calculate the length increment ΔL of the membrane layer for multiple measurements, ΔL1 = L2 - L1, ΔL n-1 =L n -L n-1 ; Calculate the rotation angle increment Δθ of the winding roller for multiple tests, Δθ1=θ2-θ1, Δθ n-1 =θ n -θ n-1 ; The obtained data is fitted to obtain a second linear function that describes the change in the length increment of the film layer as a function of the rotation angle increment of the winding roller, and the slope of the second linear function is the thickness of the film layer.

16. The film thickness measurement method as described in claim 13, characterized in that, The detection of the length of the film layer wound onto the winding roller and the corresponding rotation angle of the winding roller includes: During the process of the winding roller winding the film layer for a complete turn, the length of the film layer is detected twice to obtain the length change value ΔD of the film layer, and the rotation angle of the winding roller is detected twice to obtain the rotation angle change value Δα of the winding roller. The step of calculating the thickness of the film layer based on the length of the film layer and the rotation angle of the winding roller includes: The film thickness t of this turn is calculated using the following formula: ΔD=(r0+(n-1)t)Δα, where r0 is the initial radius of the winding roller and n is the number of turns. The thickness of the film layer is calculated over multiple turns. The obtained data is fitted to obtain a constant function of the film layer thickness as a function of the number of turns. The constant value of the constant function is the thickness of the film layer.

17. A production line for a single battery cell, characterized in that, Includes the film thickness measuring device according to any one of claims 1-12.

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