WO2023028923A1

WO2023028923A1 - Measurement method and apparatus for winding electrode assembly

Info

Publication number: WO2023028923A1
Application number: PCT/CN2021/116046
Authority: WO
Inventors: 谢金潭; 陈继伟; 王绪明
Original assignee: 宁德时代新能源科技股份有限公司
Priority date: 2021-09-01
Filing date: 2021-09-01
Publication date: 2023-03-09
Also published as: CN116670885A

Abstract

A measurement method and apparatus for a winding electrode assembly (102). The measurement method comprises: acquiring pixel equivalent parameters corresponding to the ith circle of a winding reference electrode assembly (1'), the pixel equivalent parameters comprising a first pixel equivalent of a first anode pole piece (11') and a second pixel equivalent of a first cathode pole piece (12') of the reference electrode assembly (1'); during the process of winding the ith circle of an electrode assembly to be measured (1), capturing an image of a second anode pole piece (11) of the electrode assembly to be measured (1), obtaining from the image a first pixel coordinate of a width edge of the second anode pole piece (11), capturing an image of a second cathode pole piece (12) of the electrode assembly to be measured (1), and obtaining from the image a second pixel coordinate of a width edge of the second cathode pole piece (12); and, according to the first pixel equivalent and the second pixel equivalent corresponding to the ith circle of the reference electrode assembly (1'), as well as the first pixel coordinate and the second pixel coordinate of the ith circle of the electrode assembly to be measured (1), calculating, along the winding axis (K), the excess width Wi of the second anode pole piece (11) in the ith circle of the electrode assembly to be measured (1) relative to the second cathode pole piece (12).

Description

Measuring method and device for winding electrode assembly

technical field

The present application relates to the field of battery technology, in particular to a method and device for measuring a wound electrode assembly.

Background technique

As batteries such as lithium-ion have the advantages of high energy density, high power density, many cycle times, and long storage time, they have been widely used in electric vehicles.

In the production process of lithium batteries, it is necessary to wind the anode pole piece, the cathode pole piece, and the diaphragm into a battery cell. This process has various standard requirements for the pole pieces in the winding process. One of the most important requirements is that the width of the anode pole piece beyond the cathode pole piece remains consistent during the winding process, that is, the anode pole piece and the cathode pole piece Alignment in the width direction. The detection accuracy of this parameter directly affects the performance of the battery, but improving the detection accuracy of this parameter has always been a difficult problem in the industry.

Contents of the invention

The purpose of this application is to improve the performance of the battery.

According to the first aspect of the present application, a method for measuring a wound electrode assembly is provided, including:

Obtaining the pixel equivalent step: obtaining the pixel equivalent parameters corresponding to the i-th circle of the reference electrode assembly, the pixel equivalent parameters include: the first pixel equivalent of the first anode electrode piece of the reference electrode assembly and the second pixel equivalent of the first cathode electrode assembly , 1≤i≤n, and i is a natural number, n is the total number of turns;

The step of obtaining pixel coordinates: during the process of winding the i-th circle of the electrode assembly to be tested, taking an image of the second anode pole piece of the electrode assembly to be tested, and obtaining the first pixel coordinates of the width edge of the second anode pole piece from the image, And taking an image of the second cathode pole piece of the electrode assembly to be tested, and obtaining the second pixel coordinates of the width edge of the second cathode pole piece from the image;

Calculate the excess width step: calculate the first pixel equivalent and the second pixel equivalent corresponding to the i-th circle of the reference electrode assembly, and the first pixel coordinates and second pixel coordinates of the i-th circle of the electrode assembly to be tested, calculate the second pixel of the electrode assembly to be tested The excess width Wi of the second anode pole piece relative to the second cathode pole piece along the winding axis in the i circle.

In this embodiment of the present application, the first pixel equivalent is respectively obtained for each circle of the first anode pole piece in the reference electrode assembly, and the second pixel equivalent is respectively obtained for each circle of the first cathode pole piece, which can be used in the electrode assembly to be tested In the process of winding different circles, the corresponding first pixel equivalent and second pixel equivalent are used to calculate the excess width Wi of the circle, and the algorithm can automatically compensate the change of pixel equivalent in the winding process of the electrode assembly to be tested, which can improve Computation precision beyond width Wi.

By improving the calculation accuracy beyond the width Wi, the alignment of the second anode pole piece and the second cathode pole piece along the winding axis in the electrode assembly to be tested can be improved, thereby making it easier for lithium ions to intercalate into the anode activity of the second anode pole piece material area, to prevent the phenomenon of lithium ionization, and to make the cathode active material on the second cathode sheet fully play its role, thereby improving the performance of the battery cell, and improving the cycle life and fast charge capacity of the battery cell, and can also reduce Safety issues such as combustion and explosion.

In addition, the winding electrode assembly measurement method of the present application can reduce the requirements for the imaging accuracy of the first imaging component and the second imaging component, without selecting higher-precision imaging components, and without setting a driving mechanism to make the first imaging component and the second imaging component Parts movement saves space and facilitates installation in tight spaces within the winder, thereby reducing costs.

In some embodiments, the method of measuring the wound electrode assembly further includes:

Step of calibrating pixel equivalent: in the process of winding the i-th circle of the reference electrode assembly, according to the image of the first anode pole piece and the actual size of the first anode pole piece, calibrate the first pixel equivalent of the i-th circle of the reference electrode assembly; And according to the image of the first cathode pole piece and the actual size of the first cathode pole piece, the second pixel equivalent of the i-th circle of the reference electrode assembly is calibrated.

This embodiment of the present application can pre-calibrate the first pixel equivalent and the second pixel equivalent of each circle during the process of winding the reference electrode assembly, and then use the pre-calibration when winding the electrode assembly to be tested. The pixel equivalent parameter obtained can automatically compensate the change of pixel equivalent during the winding process of the electrode assembly to be tested, thereby improving the calculation accuracy beyond the width Wi, and further improving the performance, life and safety of the battery cell.

In some embodiments, according to the image of the first anode pole piece and the actual size of the first anode pole piece, demarcating the first pixel equivalent of the i-th circle of the reference electrode assembly includes:

Obtain the image of the first anode pole piece in the i-th circle, and obtain the first calibration pixel coordinates of the width edge of the first anode pole piece from the image;

measuring a first actual width of the first anode pole piece;

The first pixel equivalent is calculated according to the first calibrated pixel coordinates and the first actual width.

In this embodiment of the present application, in the process of winding the i-th circle of the reference electrode assembly, the pixel width dimension of the first anode pole piece can be obtained through the image, and the physical width dimension of the first anode pole piece can be measured, thereby calculating The first pixel equivalent. Since the overall width of the first anode electrode piece is relatively large, the measurement of the physical width dimension and the acquisition of the pixel width dimension are more accurate, and the accuracy of the first pixel equivalent calibration can be improved. Optionally, the first pixel equivalent may also be calibrated based on the portion exceeding the width Wi.

In some embodiments, according to the image of the first cathode pole piece and the actual size of the first cathode pole piece, demarcating the second pixel equivalent of the i-th circle of the reference electrode assembly includes:

Obtain the image of the first cathode pole piece in the i-th circle, and obtain the second calibration pixel coordinates of the width edge of the first cathode pole piece from the image;

measuring a second actual width of the first cathode tab;

The second pixel equivalent is calculated according to the second calibration pixel coordinates and the second actual width.

In this embodiment of the present application, in the process of winding the i-th circle of the reference electrode assembly, the pixel width dimension of the first cathode pole piece can be obtained through the image, and the physical width dimension of the first cathode pole piece can be measured, thereby calculating Second pixel equivalent. Since the overall width of the first cathode electrode piece is larger, the measurement of the physical width dimension and the acquisition of the pixel width dimension are more accurate, and the accuracy of the second pixel equivalent calibration can be improved.

After the step of calibrating the pixel equivalent, the number of turns in the winding process of the reference electrode assembly is stored in correspondence with the first pixel equivalent and the second pixel equivalent.

In this embodiment, after the pixel equivalent parameters of each circle of the reference electrode assembly are calibrated, the pixel equivalent parameters of each circle and the number of circles are stored according to the corresponding relationship, which is convenient to call when the calculation exceeds the width Wi, so as to efficiently calculate Measure the excess width Wi corresponding to each circle of the electrode assembly.

In some embodiments, the step of calculating the excess width includes:

According to the first pixel equivalent of the i-th circle of the reference electrode assembly and the first pixel coordinates of the second anode pole piece width edge of the i-th circle of the electrode assembly to be tested, the distance between the width edge of the second anode pole piece relative to the reference line The first distance L1i of ;

According to the second pixel equivalent of the i-th circle of the reference electrode assembly and the second pixel coordinates of the second cathode pole piece width edge of the i-th circle of the electrode assembly to be tested, the distance between the width edge of the second cathode pole piece relative to the reference line is obtained The second distance Li;

According to the difference between the first distance L1i and the second distance Li, the excess width Wi of the i-th circle of the second anode pole piece relative to the second cathode pole piece is calculated.

This embodiment of the present application can obtain the excess width Wi of the second anode pole piece of the i-th circle relative to the second cathode pole piece based on the pixel equivalent parameters corresponding to each i circle in the reference electrode assembly, and can accurately and conveniently calculate the excess width Wi Width Wi to improve the performance, lifetime and safety of battery cells.

In some embodiments, calculating the excess width Wi of the second anode pole piece relative to the second cathode pole piece according to the difference between the first distance L1i and the second distance Li includes:

Obtain the deviation adjustment value in advance;

The excess width Wi of the second anode pole piece relative to the second cathode pole piece is calculated by summing the difference value and the deviation adjustment value.

This embodiment of the present application considers that there is a deviation in the actual physical positions of the first photographing component and the second photographing component in the direction of the winding axis. By introducing a deviation adjustment value, the first photographing component and the second photographing component can respectively photograph The centerlines of the images are coincident so as to unify the benchmarks for obtaining the first pixel coordinates and the second pixel coordinates and improve the accuracy of calculation results.

In some embodiments, during the process of winding the electrode assembly to be tested, the step of obtaining pixel coordinates is sequentially performed from the first turn to the nth turn, and after all the steps of obtaining pixel coordinates are completed, the electrode assembly to be tested is then Execute calculations beyond the width step in each circle to get W1,W,...,Wi,Wn;

Wound electrode assembly measurement methods also include:

In the case that the difference between the maximum excess width and the minimum excess width among W1, W, .

In this embodiment of the present application, after the winding of the electrode assembly to be tested is completed, the excess width Wi of each circle is calculated separately, so as to judge whether the winding of the electrode assembly to be tested is qualified. Width Wi is compared to obtain the maximum deviation, as long as the maximum deviation does not exceed the preset deviation, it is determined that the winding is qualified. Moreover, this method can also make the overall winding process of the electrode assembly to be tested more continuous, keep the tension of the electrode piece uniform during the winding process, and improve the winding efficiency.

According to a second aspect of the present application, a wound electrode assembly measurement device is provided, comprising:

The first photographing part is configured to photograph the image of the first anode pole piece of the reference electrode assembly, or the image of the second anode pole piece of the electrode assembly to be tested;

The second photographing part is configured to photograph the image of the first cathode pole piece of the reference electrode assembly, or the image of the second cathode pole piece of the electrode assembly to be tested; and

The control part is configured to obtain the pixel equivalent parameter corresponding to the i-th circle of the winding reference electrode assembly, the pixel equivalent parameter includes: the first pixel equivalent of the first anode pole piece of the reference electrode assembly and the second pixel of the first cathode pole piece Equivalent; and in the process of winding the i-th circle of the electrode assembly to be tested, obtain the image of the second anode pole piece of the electrode assembly to be tested, obtain the first pixel coordinates of the width edge of the second anode pole piece from the image, and obtain The image of the second cathode pole piece of the electrode assembly to be tested obtains the second pixel coordinates of the width edge of the second cathode pole piece from the image; then according to the first pixel equivalent and the second pixel equivalent of the i-th circle of the reference electrode assembly, and The first pixel coordinate and the second pixel coordinate of the i-th circle of the electrode assembly to be tested are used to calculate the excess width Wi of the second anode pole piece relative to the second cathode pole piece along the winding axis in the i-th circle of the electrode assembly to be tested.

In this embodiment of the present application, the first pixel equivalent is respectively obtained for each circle of the first anode pole piece in the reference electrode assembly, and the second pixel equivalent is respectively obtained for each circle of the first cathode pole piece, which can be used in the electrode assembly to be tested In the process of winding different circles, the corresponding first pixel equivalent and second pixel equivalent are used to calculate the excess width Wi of the circle, and the algorithm can automatically compensate the change of pixel equivalent in the winding process of the electrode assembly to be tested, which can improve The calculation accuracy exceeds the width Wi, thereby improving the performance, life and safety of the battery cell.

In addition, the winding electrode assembly measurement method of the present application can reduce the requirements for the shooting accuracy of the first shooting part and the second shooting part. Parts and second camera part move, save space and facilitate installation in tight spaces in the winder, thereby reducing costs.

In some embodiments, the first imaging component and the second imaging component are fixed on the same side of the winding axis of the reference electrode assembly or the electrode assembly to be tested.

In this embodiment of the present application, the first photographing part and the second photographing part are arranged on the same side of the winding shaft, which can save space occupied in the winding machine, facilitate installation, and facilitate selection based on the installation position of the photographing part. baseline. In addition, the first photographing part and the second photographing part are fixedly arranged, and there is no need to set a driving mechanism to move the first photographing part and the second photographing part, which can further save space and facilitate installation in a narrow space in the winding machine, thereby enabling cut costs.

In some embodiments, the control components include:

The calibration unit is configured to calibrate the first pixel equivalent of the i-th circle of the reference electrode assembly according to the image of the first anode pole piece and the actual size of the first anode pole piece in the process of winding the i-th circle of the reference electrode assembly and according to the image of the first cathode pole piece and the actual size of the first cathode pole piece, demarcate the second pixel equivalent of the i-th circle of the reference electrode assembly.

In some embodiments, the wound electrode assembly measurement device further includes:

a measuring component configured to measure a first actual width of the first anode tab and a second actual width of the first cathode tab in the reference electrode assembly;

Wherein, the calibration unit is configured to acquire the image of the i-th circle of the first anode pole piece, and obtain the first calibration pixel coordinates of the width edge of the first anode pole piece from the image, according to the first calibration pixel coordinates and the first actual width, Calculate the first pixel equivalent; and acquire the image of the i-th circle of the first cathode pole piece, and obtain the second marked pixel coordinates of the width edge of the first cathode pole piece from the image, according to the second marked pixel coordinates and the second actual width , to calculate the second pixel equivalent.

This embodiment of the present application can obtain the pixel width dimensions of the first anode pole piece and the first cathode pole piece through images during the process of winding the i-th circle of the reference electrode assembly, and measure the first anode pole piece and the first cathode pole piece. The physical width dimension of the cathode pole piece, from which the first pixel equivalent and the second pixel equivalent are calculated. Since the overall width of the first anode pole piece and the first cathode pole piece is relatively large, the measurement of the physical width dimension and the acquisition of the pixel width dimension are more accurate, and the accuracy of the calibration of the first pixel equivalent and the second pixel equivalent can be improved .

The storage unit is configured to store the calibrated number of turns in the winding process of the reference electrode assembly corresponding to the first pixel equivalent and the second pixel equivalent.

In some embodiments, the control components include:

The alignment calculation unit is configured to, during the process of winding the i-th turn of the electrode assembly, according to the first pixel equivalent of the i-th turn of the reference electrode assembly and the second anode pole piece width edge of the i-th turn of the electrode assembly to be tested One pixel coordinates, obtain the first distance L1i between the width edge of the second anode pole piece with respect to the reference line; And according to the second pixel equivalent of the i-th circle of the reference electrode assembly and the second The second pixel coordinates of the width edge of the cathode pole piece obtains the second distance Li between the width edge of the second cathode pole piece relative to the reference line; then calculates the first distance according to the difference between the first distance L1i and the second distance Li The excess width Wi of the two anode pole pieces relative to the second cathode pole piece.

In some embodiments, the alignment calculation unit is configured to sum the difference value and the pre-acquired deviation adjustment value to calculate the excess width Wi of the second anode pole piece relative to the second cathode pole piece.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the accompanying drawings that need to be used in the embodiments of the present application. Obviously, the accompanying drawings described below are only some embodiments of the present application. Those of ordinary skill in the art can also obtain other drawings based on the accompanying drawings on the premise of not paying creative efforts.

FIG. 1 is an exploded view of some embodiments of battery cells in the present application.

FIG. 2 is a schematic view of some embodiments of the electrode assembly in FIG. 1 before being wound.

FIG. 3 is an enlarged view of A in FIG. 2 .

FIG. 4 is a schematic structural view of some embodiments of the electrode assembly in FIG. 1 after being wound.

Fig. 5 is a schematic structural view of some embodiments of the measuring device for the wound electrode assembly of the present application.

Fig. 6 is a schematic diagram of the size of the second anode pole piece exceeding the second cathode pole piece along the winding axis in the electrode assembly to be tested;

Fig. 7 is a schematic flowchart of some embodiments of the method for measuring a wound electrode assembly of the present application.

FIG. 8 is a schematic flowchart of another embodiment of the method for measuring a wound electrode assembly of the present application.

FIG. 9 is a schematic flow chart of calibrating the first pixel equivalent in the step of calibrating the pixel equivalent.

FIG. 10 is a schematic flow chart of calibrating the second pixel equivalent in the step of calibrating the pixel equivalent.

Fig. 11 is a schematic flowchart of some other embodiments of the method for measuring a wound electrode assembly of the present application.

Figure 12 is a flow diagram of some embodiments of the step of calculating the excess width.

Fig. 13 is a schematic diagram of the module composition of some embodiments of the device for measuring the wound electrode assembly of the present application.

Fig. 14 is a schematic diagram of the module composition of other embodiments of the wound electrode assembly measuring device of the present application.

In the drawings, the drawings are not drawn to scale.

The reference numerals in the specific embodiment are as follows:

10. Battery cell; 101. Shell; 102. Electrode assembly; 103. Adapter; 104. End cap assembly; 104A. End cap body; 104B. Positive terminal; 104C. Negative terminal; 104D. Pressure relief component;

1', reference electrode assembly; 11', first anode pole piece; 12', first cathode pole piece; 13', first diaphragm; K, winding shaft; BL, reference line;

1. The electrode assembly to be tested; 11. The second anode pole piece; 12. The second cathode pole piece; 13. The second diaphragm;

2. The first photographing component; 3. The second photographing component; 4. The control component; 41. The calibration unit; 42. The alignment calculation unit; 5. The measuring component; 6. The storage component.

Detailed ways

The implementation manner of the present application will be further described in detail below with reference to the drawings and embodiments. The detailed description and drawings of the following embodiments are used to illustrate the principles of the application, but not to limit the scope of the application, that is, the application is not limited to the described embodiments.

In the description of this application, it should be noted that, unless otherwise specified, the meaning of "plurality" is more than two; the terms "upper", "lower", "left", "right", "inner", " The orientation or positional relationship indicated by "outside" and so on are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a reference to this application. Application Restrictions.

In addition, the terms "first", "second", "third", etc. are used for descriptive purposes only and should not be construed as indicating or implying relative importance. "Vertical" is not strictly vertical, but within the allowable range of error. "Parallel" is not strictly parallel, but within the allowable range of error. The orientation words appearing in the following description are the directions shown in the figure, and do not limit the specific structure of the application.

In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be interpreted in a broad sense, for example, it can be a fixed connection or a flexible connection. Disassembled connection, or integral connection; it can be directly connected or indirectly connected through an intermediary. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific situations.

Reference herein to an "embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. The occurrences of this phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is understood explicitly and implicitly by those skilled in the art that the embodiments described herein can be combined with other embodiments.

In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two), similarly,

"Multiple groups" means more than two groups (including two groups), and "multiple pieces" means more than two pieces (including two pieces).

In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical" "Horizontal", "Top", "Bottom", "Inner", "Outer", "Clockwise", "Counterclockwise", "Axial", "Radial", "Circumferential", etc. indicate the orientation or positional relationship based on the drawings Orientation or positional relationship is only for the convenience of describing the embodiment of the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as an implementation of the present application. Example limitations.

At present, judging from the development of the market situation, the application of power batteries is becoming more and more extensive. Power batteries are not only used in energy storage power systems such as hydraulic, thermal, wind and solar power plants, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric vehicles, as well as military equipment and aerospace and other fields . With the continuous expansion of power battery application fields, its market demand is also constantly expanding.

During the use of batteries, there are problems of easy performance degradation and short cycle life, and even safety problems in some cases. Over the years, those skilled in the art have tried to solve this problem from many different angles, but the desired effect has not been achieved.

As part of the invention and creation process of the present application, the inventor has gone through numerous tests and verifications, and analyzed the electrode assembly in the battery, and found that one of the reasons for the above-mentioned problems in the battery is that the anode sheet in the electrode assembly exceeds the cathode sheet The width dimension of the anode pole piece cannot be kept consistent during the winding process, that is, the alignment accuracy of the anode pole piece and the cathode pole piece in the width direction is low. The existence of this problem may make it difficult for lithium ions to intercalate into the anode active material area of the anode pole piece, resulting in the phenomenon of lithium ionization, and it is difficult for the cathode active material of the cathode pole piece to fully play its role, thereby affecting the performance of the battery and making the battery The cycle life is greatly shortened, and the fast charging capacity of the battery is limited, and it may also cause safety problems such as combustion and explosion.

In order to solve this problem, during the winding process of the electrode assembly, the images of the anode pole piece and the cathode pole piece are respectively taken by two shooting parts at a preset distance, so as to calculate the excess of the anode pole piece relative to the cathode pole piece according to the image. width.

However, the inventor noticed that the calculated value of the above-mentioned width depends on the pixel equivalent of the photographing component, and the pixel equivalent is the actual physical size represented by a pixel in the image. However, with the continuous winding of the pole piece, the electrode assembly becomes thicker and thicker, and the distance between the two photographing parts and the corresponding pole piece is changing dynamically. Because the photographing part has the phenomenon of "near large and far small", the pixel The equivalent is also changing dynamically. If a fixed pixel equivalent is used to calculate the excess width, an error will occur in the calculation of the excess width.

In order to compensate for the change of the pixel equivalent caused by the change of the distance between the photographing part and the pole piece, if the photographing part is moved by the driving mechanism during the winding process, so that the distance between the photographing part and the pole piece is always kept at the optimum shooting focal length value, this The method also faces many problems in the actual application process. For example, the internal space of the winding machine is small and it is difficult to reserve additional space. The control accuracy of the driving mechanism is high, and the maintenance of the driving mechanism is difficult and the cost is high.

Based on the above considerations, after in-depth research, the inventor proposed the idea of layered calibration of the electrode assembly, and based on this idea, a measurement method for the winding electrode assembly was designed, including: the step of obtaining pixel equivalent, the step of obtaining pixel coordinates and the calculation Width step exceeded.

Among them, the step of obtaining pixel equivalent: obtaining the pixel equivalent parameter corresponding to the i-th circle of the winding reference electrode assembly, the pixel equivalent parameter includes: the first pixel equivalent of the first anode pole piece of the reference electrode assembly and the second pixel equivalent of the first cathode pole piece Pixel equivalent, 1≤i≤n, and i is a natural number, n is the total number of turns.

In this winding electrode assembly measurement method, the first pixel equivalent is obtained for each circle of the first anode pole piece in the reference electrode assembly, and the second pixel equivalent is respectively obtained for each circle of the first cathode pole piece. In the process of winding different turns of the electrode assembly, the corresponding first pixel equivalent and second pixel equivalent are used to calculate the excess width Wi, and the algorithm can automatically compensate the change of the pixel equivalent during the winding process of the electrode assembly, which can exceed the width Wi. Computational accuracy to improve battery performance, lifespan and safety. Moreover, the requirement on the shooting accuracy of the shooting part can be reduced, and there is no need to set a driving mechanism to move the shooting part, which is convenient for installation in the winding machine and can also reduce the cost.

In order to describe the wound electrode assembly measurement method of the present application more clearly, as shown in FIG. 1 , the structure of the smallest unit battery cell 10 in the battery will be firstly described below.

The battery cell 10 includes a casing 101, an electrode assembly 102, and an end cap assembly 104. The end cap assembly 104 is connected to the casing 101 to form the shell of the battery cell 10. The electrode assembly 102 is arranged in the casing 101, and the casing 101 Fill with electrolyte. The battery cell 10 can be square, cylindrical or other shapes.

The end cap assembly 104 is disposed on the top of the electrode assembly 102, and the end cap assembly 104 includes an end cap body 104A, a positive terminal 104B, a negative terminal 104C and a pressure relief component 104D. Wherein, the positive terminal 104B and the negative terminal 104C are respectively provided with an adapter piece 103 , and the adapter piece 103 is located between the end cap body 104A and the electrode assembly 102 . For example, the tab 102A of the electrode assembly 102 in FIG. 1 is located at the top, the cathode tab is connected to the positive terminal 104B through an adapter 103 , and the anode tab is connected to the negative terminal 104C through another adapter 103 . The pressure relief component 104D is disposed on the end cap body 104A and is configured to be activated to release the internal pressure of the battery cell 10 when the internal pressure of the battery cell 10 reaches a threshold.

According to actual usage requirements, the electrode assembly 102 can be configured as a single or multiple. As shown in FIG. 1 , at least two independently wound electrode assemblies 102 may also be provided in the battery cell 10 . The electrode assembly 102 needs to measure the excess width Wi of the anode pole piece relative to the cathode pole piece during the winding process, so it is called the electrode assembly 1 to be tested, and the standard electrode assembly used to obtain the pixel equivalent parameter is called The reference electrode assembly 1' is a normally manufactured and qualified electrode assembly used to obtain pixel equivalent parameters. In fact, the electrode assembly 1 to be tested has the same structure as the reference electrode assembly 1', and the following is only given for the convenience of description. different names and reference signs.

As shown in Fig. 2 and Fig. 3, the reference electrode assembly 1' can be made by combining the first anode pole piece 11', the first cathode pole piece 12' and the first anode pole piece 11' and the first cathode pole piece 12 'The first separator 13' is wound together to form a wound electrode assembly, as shown in FIG. 4 . For example, before winding, the first diaphragm 13 ′, the first anode pole piece 11 ′, the first diaphragm 13 ′ and the first cathode pole piece 12 ′ can be stacked in sequence from bottom to top, and the first diaphragm 13 ′ is An insulator interposed between the first anode pole piece 11' and the first cathode pole piece 12'. Wherein, the anode active material such as graphite or silicon can be coated on the first anode pole piece 11'; the cathode active material can be coated on the first cathode pole piece 12', such as ternary material, lithium manganate or lithium iron phosphate. After winding, the reference electrode assembly 1' can be a flat structure as shown in FIG. 4, or it can also be a circular structure as shown in FIG.

Similarly, the electrode assembly 1 to be tested can be formed by winding the second anode pole piece 11, the second cathode pole piece 12 and the second diaphragm 13 for isolating the second anode pole piece 11 and the second cathode pole piece 12 together. Wound electrode assembly.

As shown in FIG. 5 , taking the electrode assembly 1 to be tested as an example, the stacked second anode pole piece 11 , second cathode pole piece 12 and second separator 13 are stretched into the winding machine, and the winding shaft K Winding is carried out at the winding station as the center, the winding station can be used to wind the electrode assembly 1 to be tested, and the first photographing part 2 and the second photographing part 3 are arranged on the same side of the winding axis K, for example , the shooting component can be various cameras. In order to obtain a clear image, the first photographing part 2 and the second photographing part 3 can adopt different photographing angles. Optionally, a reference electrode assembly 1' can also be set on the winding station, so as to obtain pixel equivalent parameters during the process of winding the reference electrode assembly 1'.

The first photographing part 2 is configured to photograph the image of the second anode pole piece 11 of the electrode assembly 1 to be tested, specifically, an infrared camera can be used to photograph the second anode pole piece wound on the winding shaft K through the second diaphragm 13 11. The distance between the first photographing component 2 and the second anode electrode piece 11 is S1.

The second photographing part 3 is configured to photograph the image of the second cathode pole piece 12 of the electrode assembly 1 to be tested, specifically, the second cathode pole piece 12 to be wound on the winding shaft K can be photographed, and the second photographing part The distance between 3 and the second cathode pole piece 12 is S2.

As shown in FIG. 6 , in the process of winding the i-th turn of the electrode assembly 1 to be tested, it is necessary to make the second anode pole piece 11 relative to the second cathode pole piece 12 on both sides along the winding axis K. Width Wi. The method and device for measuring the excess width Wi will be described in detail below with reference to FIGS. 7 to 14 .

In some embodiments, as shown in FIG. 7 , the method for measuring a wound electrode assembly of the present disclosure includes:

S110. Obtaining the pixel equivalent step: obtaining the pixel equivalent parameter corresponding to the i-th circle around the reference electrode assembly 1', the pixel equivalent parameter includes: the first pixel equivalent and the first pixel equivalent of the first anode electrode piece 11' of the reference electrode assembly 1' The second pixel equivalent of the cathode electrode piece 12 ′, wherein, 1≤i≤n, and i is a natural number, and n is the total number of turns.

S120. Step of acquiring pixel coordinates: during the process of winding the i-th turn of the electrode assembly 1 to be tested, take an image of the second anode electrode piece 11 of the electrode assembly 1 to be tested, and obtain the width edge of the second anode electrode sheet 11 from the image and take an image of the second cathode pole piece 12 of the electrode assembly 1 to be tested, and obtain the second pixel coordinates of the width edge of the second cathode pole piece 12 from the image.

S130, the step of calculating the excess width: according to the first pixel equivalent and the second pixel equivalent corresponding to the i-th circle of the reference electrode assembly 1', and the first pixel coordinate and the second pixel coordinate of the i-th circle of the electrode assembly 1 to be tested, calculate The excess width Wi of the second anode pole piece 11 relative to the second cathode pole piece 12 along the winding axis K in the i-th turn of the electrode assembly 1 to be tested.

Wherein, in S101, it is assumed that the pixel equivalent parameter corresponding to the i-th circle of the winding reference electrode assembly 1' has been obtained through calibration or other methods, and stored in the storage unit 6, and before the exceeding width Wi is calculated, the control unit 4 Obtain the pixel equivalent parameter from the storage unit 6.

For example, if the excess width Wi of each circle is calculated after the winding of the electrode assembly 1 to be tested is completed, the pixel equivalent parameters of the 1st to nth circles can be calculated before, during, or after the winding of the electrode assembly 1 to be tested. Obtained at one time; if the excess width Wi of the i-th circle is calculated after the winding of the i-th circle is completed, the pixel equivalent parameter of the i-th circle can be obtained before the electrode assembly 1 to be tested is wound, before starting to wind the i-th circle, or after winding Obtained during the i-th circle.

The reference electrode assembly 1' is a standard electrode assembly manufactured to obtain pixel equivalent parameters, and the pixel equivalent is the actual physical size represented by a pixel point in the image. The pixel equivalent parameters include: the first pixel equivalent of the first anode electrode piece 11' of the reference electrode assembly 1' and the second pixel equivalent of the first cathode electrode sheet 12'. The first pixel equivalents corresponding to the first anode pole pieces 11' of the 1st to nth circles in the reference electrode assembly 1' are all different, and the second pixel equivalents corresponding to the first cathode pole pieces 12' of the 1st to nth circles are all different . Therefore, when calculating the excess width Wi of the i-th circle, the change of the shooting distance during the winding process can be compensated by adjusting the pixel equivalent parameter of each circle.

In S120, in the process of winding the i-th turn of the electrode assembly 1 to be tested, the images of the second anode electrode piece 11 and the second cathode electrode piece 12 are respectively captured by the first photographing part 2 and the second photographing part 3, Images can be numbered and named according to the number of laps. Next, the first pixel coordinates of the width edge of the second anode pole piece 11 and the second pixel coordinates of the width edge of the second cathode pole piece 12 are obtained from the image. Wherein, the first pixel coordinate represents the position of the width edge of the second anode pole piece 11 in the image, and the second pixel coordinate represents the position of the width edge of the second cathode pole piece 12 in the image.

In S130, referring to FIG. 6, the length segment between the two dotted lines indicates that the pole piece is wound around one circle. When calculating the excess width Wi of the i-th circle of the electrode assembly 1 to be tested, the basic principle adopted is to multiply the pixel equivalent by the pixel Coordinates are equal to actual physical dimensions. As shown in FIG. 6 , the second anode pole piece 11 can exceed the second cathode pole piece 12 on both sides along the winding axis K, and for the i-th turn, the excess width Wi on both sides can be the same or different.

Specifically, the first pixel equivalent corresponding to the i-th circle of the reference electrode assembly 1' is multiplied by the first pixel coordinate of the width edge of the second anode pole piece 11 in the i-th circle of the electrode assembly 1 to be tested, and the second anode pole piece 11 can be obtained The actual physical position of the width edge; the second pixel equivalent corresponding to the i-th circle of the reference electrode assembly 1' is multiplied by the second pixel coordinates of the width edge of the second cathode pole piece 12 in the i-th circle of the electrode assembly 1 to be tested, to obtain the second The actual physical position of the width edge of the cathode pole piece 12, thus, the excess width Wi of the second anode pole piece 11 relative to the second cathode pole piece 12 along the winding axis K in the i-th turn of the electrode assembly 1 to be tested can be calculated. Wherein, the winding axis K is consistent with the width direction of the second anode pole piece 11 or the second cathode pole piece 12 .

For the execution sequence of each step in this embodiment: if the excess width Wi of each circle is calculated after the winding of the electrode assembly 1 to be tested is completed, S120 is executed once for each winding circle, so as to obtain the width of each circle during the winding process. After the electrode assembly 1 to be tested is wound, S130 is performed uniformly for each circle, and S110 corresponding to each circle can be performed uniformly before winding the electrode assembly 1 to be tested, or during the winding process, or during the winding process. Execute before executing S130 after winding is completed. If the excess width Wi of the i-th turn is calculated after the winding of the i-th turn is completed, S110, S120 and S130 for the i-th turn can be executed sequentially.

In this embodiment of the present application, the first pixel equivalent is respectively obtained for each circle of the first anode pole piece 11' in the reference electrode assembly 1', and the second pixel equivalent is respectively obtained for each circle of the first cathode pole piece 12', In the process of winding different circles of the electrode assembly 1 to be tested, the corresponding first pixel equivalent and second pixel equivalent can be used to calculate the excess width Wi of the circle, and the pixel equivalent can be automatically compensated by the algorithm. The change in the winding process can improve the calculation accuracy beyond the width Wi.

By improving the calculation accuracy beyond the width Wi, the alignment of the second anode pole piece 11 and the second cathode pole piece 12 along the winding axis K in the electrode assembly 1 to be tested can be improved, thereby making it easier for lithium ions to intercalate into the second anode pole. The anode active material area of the sheet 11 prevents the phenomenon of lithium ionization, and makes the cathode active material on the second cathode sheet 12 fully play its role, thereby improving the performance of the battery cell 10 and improving the cycle of the battery cell 10 Long life and fast charging capacity can also reduce safety problems such as combustion and explosion.

In addition, the winding electrode assembly measurement method of the present application can reduce the requirements for the imaging accuracy of the first imaging component 2 and the second imaging component 3, without selecting higher-precision imaging components, and without setting a driving mechanism to make the first imaging component 2 and the second imaging component 3 The second photographing part 3 moves, saves space, and is convenient for installation in a narrow space in the winding machine, thereby reducing costs.

In some embodiments, the first pixel equivalent of the i+1th circle is smaller than the first pixel equivalent of the i-th circle, and the second pixel equivalent of the i+1th circle is greater than the second pixel equivalent of the i-th circle.

As shown in FIG. 5 , the distance between the first photographing component 2 and the second anode pole piece 11 is S1 , and the distance between the second photographing component 3 and the second cathode pole piece 12 is S2 .

As the winding thickness of the pole piece increases, S1 gradually decreases. If the first pixel equivalent remains unchanged, the actual physical size corresponding to a single pixel in the captured image will increase, so it is necessary to gradually reduce the first pixel equivalent to be accurate. The actual physical position of the width edge of the second anode pole piece 11 can be calculated accurately. Therefore, the first pixel equivalent of the i+1th circle is smaller than the first pixel equivalent of the i-th circle.

As the winding thickness of the pole piece increases, S2 gradually increases. If the second pixel equivalent remains unchanged, the actual physical size corresponding to a single pixel in the captured image will decrease. Therefore, it is necessary to gradually increase the second pixel equivalent to be accurate. The actual physical position of the width edge of the second cathode pole piece 12 can be calculated accurately. Therefore, the second pixel equivalent of the i+1th circle is greater than the second pixel equivalent of the i-th circle.

In this embodiment of the present application, by setting the first pixel equivalents of the 1st to nth circles in the reference electrode assembly 1' to gradually decrease, and the second pixel equivalents to gradually increase, it is possible to automatically compensate for the pixel equivalents to be measured. The change in the winding process of the electrode assembly 1 improves the calculation accuracy of the excess width Wi, thereby improving the performance, life and safety of the battery cell 10 .

In some embodiments, as shown in FIG. 8, the method for measuring the wound electrode assembly further includes:

S100. Step of calibrating the pixel equivalent: during the process of winding the i-th circle of the reference electrode assembly 1', according to the image of the first anode pole piece 11' and the actual size of the first anode pole piece 11', calibrate the reference electrode assembly 1 'the first pixel equivalent of the i-th circle; and according to the image of the first cathode pole piece 12' and the actual size of the first cathode pole piece 12', calibrate the second pixel equivalent of the i-th circle of the reference electrode assembly 1'.

Wherein, S100 is executed before S110. Before winding a single, multiple or batch of the same electrode assembly 1 to be tested, calibration can be performed based on the reference electrode assembly 1' in order to obtain the pixel equivalent parameters corresponding to each circle. During the calibration process, the reference electrode assembly 1' can be wound at the winding station shown in FIG. image, and measure the actual size of the first anode pole piece 11' to calibrate the first pixel equivalent of the i-th circle; or take an image of the first cathode pole piece 12' through the second photographing component 3, and measure the first cathode pole piece 12' The actual size of the pole piece 12' is to demarcate the second pixel equivalent of the i-th circle, so as to be used when calculating the excess width Wi of the i-th circle in S130.

In this embodiment of the present application, during the process of winding the reference electrode assembly 1', the first pixel equivalent and the second pixel equivalent of each circle can be pre-calibrated, and subsequently when the electrode assembly 1 to be tested is wound, it can be Using the pre-calibrated pixel equivalent parameters can automatically compensate the change of the pixel equivalent during the winding process of the electrode assembly 1 to be tested, thereby improving the calculation accuracy beyond the width Wi, and further improving the performance, life and safety of the battery cell 10 .

In some embodiments, as shown in FIG. 9, in S100, according to the image of the first anode pole piece 11' and the actual size of the first anode pole piece 11', the first pixel of the i-th circle of the reference electrode assembly 1' is marked. Equivalents include:

S101. Obtain the image of the i-th circle of the first anode pole piece 11', and obtain the first calibration pixel coordinates of the width edge of the first anode pole piece 11' from the image;

S102, measuring the first actual width of the first anode pole piece 11';

S103. Calculate a first pixel equivalent according to the first calibrated pixel coordinates and the first actual width.

Wherein, S103 is executed after S101 and S102, and the execution order of S101 and S102 is not limited.

In S101, the image of the first anode pole piece 11' photographed by the first photographing part 2 is obtained, and the first calibration pixel coordinates of the width edges on both sides of the first anode pole piece 11' are obtained from the image, so as to obtain from the image The pixel width dimension of the first anode electrode piece 11' is obtained.

In S102, the first actual width of the first anode pole piece 11' can be measured by the measuring component 5, and the measuring component 5 can be a precision image surveying instrument, thereby measuring the physical width of the first anode pole piece 11' .

In S103, specifically, the first calibration pixel coordinates of the width edges on both sides of the first anode pole piece 11' can be calculated to obtain the pixel width dimension of the first anode pole piece 11', and the first anode pole piece 11' The first pixel equivalent can be calculated by dividing the physical width dimension of the first anode electrode piece 11' by the pixel width dimension.

In this embodiment of the present application, in the process of winding the i-th circle of the reference electrode assembly 1', the pixel width dimension of the first anode pole piece 11' can be obtained through the image, and the physical width of the first anode pole piece 11' can be measured Size, from which the first pixel equivalent is calculated. Since the overall width of the first anode electrode piece 11' is relatively large, the measurement of the physical width dimension and the acquisition of the pixel width dimension are more accurate, and the accuracy of the first pixel equivalent calibration can be improved. Optionally, the first pixel equivalent may also be calibrated based on the portion exceeding the width Wi.

In some embodiments, as shown in FIG. 10, in S100, according to the image of the first cathode pole piece 12' and the actual size of the first cathode pole piece 12', the second pixel of the i-th circle of the reference electrode assembly 1' is marked. Equivalents include:

S104, acquire the image of the i-th circle of the first cathode pole piece 12', and obtain the second calibration pixel coordinates of the width edge of the first cathode pole piece 12' from the image;

S105, measuring the second actual width of the first cathode pole piece 12';

S106. Calculate a second pixel equivalent according to the second calibration pixel coordinates and the second actual width.

Wherein, S106 is executed after S104 and S105, and the execution sequence of S104 and S105 is not limited.

In S104, the image of the first cathode pole piece 12' taken by the second photographing part 3 is obtained, and the second calibration pixel coordinates of the width edges on both sides of the first cathode pole piece 12' are obtained from the image, so as to obtain from the image The pixel width dimension of the first cathode electrode piece 12' is obtained.

In S105, the second actual width of the first cathode pole piece 12' can be measured by the measuring part 5, and the measuring part 5 can be a precision image mapping instrument, thus the physical width dimension of the first cathode pole piece 12' can be measured .

In S106, specifically, the second calibration pixel coordinates of the width edges on both sides of the first cathode pole piece 12' can be calculated to obtain the pixel width dimension of the first cathode pole piece 12', and the first cathode pole piece 12' The second pixel equivalent can be calculated by dividing the physical width dimension of the first cathode electrode sheet 12' by the pixel width dimension.

In this embodiment of the present application, in the process of winding the i-th circle of the reference electrode assembly 1', the pixel width dimension of the first cathode pole piece 12' can be obtained through the image, and the physical width of the first cathode pole piece 12' can be measured Size, from which the second pixel equivalent is calculated. Since the overall width of the first cathode electrode piece 12' is relatively large, the measurement of the physical width and the acquisition of the pixel width are more accurate, and the accuracy of the second pixel equivalent calibration can be improved.

In some embodiments, as shown in Figure 11, the method for measuring the wound electrode assembly further includes:

S100', after the step of calibrating the pixel equivalent, store the number of turns in the winding process of the reference electrode assembly 1' corresponding to the first pixel equivalent and the second pixel equivalent.

Wherein, S100' is executed between S100 and S110. The "corresponding storage" here refers to storing according to the mapping relationship between the number of circles and the first pixel equivalent and the second pixel equivalent, that is, each circle corresponds to a first pixel equivalent and a second pixel equivalent. The corresponding relationship can be stored in the storage unit 6 for subsequent acquisition. The control unit 4 only needs to send the number of turns instruction to the storage unit 6, and the first pixel equivalent and the second pixel equivalent corresponding to the number of turns can be obtained by looking up the table.

In this embodiment, after the pixel equivalent parameters of each circle of the reference electrode assembly 1' are calibrated, the pixel equivalent parameters of each circle and the number of circles are stored according to the corresponding relationship, which is convenient to call when the calculation exceeds the width Wi, so as to efficiently calculate Obtain the excess width Wi corresponding to each circle of the electrode assembly 1 to be tested.

In some embodiments, as shown in FIG. 12 , the step of calculating the excess width at S130 includes:

S131. According to the first pixel equivalent of the i-th circle of the reference electrode assembly 1' and the first pixel coordinates of the width edge of the second anode pole piece 11 of the i-th circle of the electrode assembly 1 to be tested, obtain the width of the second anode pole piece 11 a first distance L1i between the edge relative to the reference line BL;

S132. According to the second pixel equivalent of the i-th circle of the reference electrode assembly 1' and the second pixel coordinates of the width edge of the second cathode pole piece 12 of the i-th circle of the electrode assembly 1 to be tested, obtain the width of the second cathode pole piece 12 a second distance L2i between the edge relative to the reference line BL;

S133 , according to the difference between the first distance L1i and the second distance L2i, calculate the excess width Wi of the second anode pole piece 11 relative to the second cathode pole piece 12 of the i-th circle.

Wherein, S133 is executed after S131 and S132, and the execution order of S131 and S132 is not limited.

In S131, the reference line BL can be selected first, and according to the first pixel coordinates of the width edge of the second anode electrode sheet 11 and the position of the reference line BL, the relationship between the width edge of the second anode electrode sheet 11 and the reference line BL in the image can be obtained. The pixel distance between; then, multiply the pixel distance of the i-th circle by the first pixel coordinates to obtain the first distance L1i between the width edge of the second anode pole piece 11 with respect to the reference line BL, the first The distance L1i is an actual physical size.

In S132, using the same reference line BL, according to the second pixel coordinates of the width edge of the second cathode electrode sheet 12 and the position of the reference line BL, the distance between the width edge of the second cathode electrode sheet 12 and the reference line BL in the image is obtained. Pixel distance; then, the pixel distance of the i-th circle is multiplied by the second pixel coordinates to obtain the second distance L2i between the width edge of the second cathode pole piece 12 with respect to the reference line BL, and the second distance L2i is actual physical size.

In S133, according to the difference between the first distance L1i and the second distance L2i, the excess width Wi of the i-th circle of the second anode pole piece 11 relative to the second cathode pole piece 12 is calculated, and the excess width of a certain side is calculated. When Wi, the pixel coordinates of the corresponding side width edges of the second anode pole piece 11 and the two cathode pole pieces 12 can be used for calculation.

This embodiment of the present application can obtain the excess width Wi of the second anode pole piece 11 of the i-th circle relative to the second cathode pole piece 12 based on the pixel equivalent parameters corresponding to each circle i in the reference electrode assembly 1', which can be accurate and convenient. The excess width Wi can be accurately calculated to improve the performance, lifespan and safety of the battery cell 10 .

In some embodiments, S133 calculates the excess width Wi of the second anode pole piece 11 relative to the second cathode pole piece 12 according to the difference between the first distance L1i and the second distance L2i, including:

Obtain the deviation adjustment value in advance;

The excess width Wi of the second anode pole piece 11 relative to the second cathode pole piece 12 is calculated by summing the difference and the deviation adjustment value.

Wherein, the deviation adjustment value can be set according to the deviation of the actual physical position of the first photographing part 2 and the second photographing part 3 in the winding axis K direction, so as to compensate the inherent error brought by the detection device, the purpose is to make the first photographing The midlines of the images captured by the component 2 and the second photographing component 3 are coincident, so as to be a reference for unified calculation of the first pixel coordinates and the second pixel coordinates.

This embodiment of the application considers that there is a deviation in the actual physical positions of the first photographing part 2 and the second photographing part 3 in the direction of the winding axis K. By introducing a deviation adjustment value, the first photographing part 2 and the second photographing part The centerlines of the images taken by the photographing components 3 are coincident so as to unify the references for obtaining the first pixel coordinates and the second pixel coordinates and improve the accuracy of the calculation results.

In some embodiments, the reference line BL is the center line of the second anode electrode piece 11 of the electrode assembly 1 to be tested located between the width edges on both sides, or the center line of the second cathode electrode piece 12 located between the width edges of the two sides Wire. Since the distance between the center line of the pole piece and the width edges on both sides of the pole piece is the same, it is possible to prevent large errors in the calculation results of the excess width Wi on both sides due to the position of the reference line BL being too close or too far away, so that both sides of the electrode assembly 1 to be tested can be Calculations beyond the width Wi are more accurate. Optionally, the reference line BL can also be selected at other positions.

In some embodiments, during the process of winding the electrode assembly 1 to be tested, the step of obtaining pixel coordinates is sequentially performed from the first turn to the nth turn, and after all the steps of obtaining pixel coordinates are completed, the electrode assembly to be tested is Each turn of 1 performs calculations beyond the width step to get W1,W2,...,Wi,Wn. Wound electrode assembly measurement methods also include:

Judging whether the difference between the maximum excess width and the minimum excess width of W1, W2,..., Wi, Wn of the electrode assembly 1 to be tested exceeds the preset deviation, and if it does not exceed, it is determined that the winding of the electrode assembly 1 to be tested is qualified, if If it exceeds, it is determined that the winding of the electrode assembly 1 to be tested is unqualified.

Wherein, in the process of winding each turn of the electrode assembly 1 to be tested, the step of acquiring pixel coordinates is sequentially performed to obtain the width of the second anode electrode piece 11 from the images captured by the first imaging component 2 and the second imaging component 3 The first pixel coordinates of the edge, and the second pixel coordinates of the width edge of the second cathode electrode piece 12 . After the electrode assembly 1 to be tested is wound, the excess width Wi of each turn is calculated separately, and whether the winding of the electrode assembly 1 to be tested is qualified is judged through S140. The preset deviation is set according to the process requirements of the electrode assembly 1 to be tested. For example, the performance of the battery cell 10 under different preset deviations is tested through experiments to obtain an acceptable preset deviation.

In this embodiment of the present application, after the winding of the electrode assembly 1 to be tested is completed, the excess width Wi of each circle is calculated separately, so as to judge whether the winding of the electrode assembly 1 to be tested is qualified. The excess width Wi is compared to obtain the maximum deviation, as long as the maximum deviation does not exceed the preset deviation, it is determined that the winding is qualified. Moreover, this method can also make the overall winding process of the electrode assembly 1 to be tested more continuous, keep the tension of the electrode piece uniform during the winding process, and improve the winding efficiency.

Optionally, the step of acquiring pixel coordinates is performed during the winding of the i-th turn of the electrode assembly 1 to be tested, and the step of calculating the excess width is performed before winding the i+1th turn. After the circle is completed, it is judged whether the excess width Wi of the circle meets the requirements, so as to meet the size requirements more strictly, and take deviation correction and adjustment measures if the requirements are not met.

Some specific examples will be given below, with reference to Figure 7 to Figure 11, the measurement method of the wound electrode assembly of the present application is as follows:

1. Start winding a reference electrode assembly 1' in the winding machine, and execute S100, the step of calibrating the pixel equivalent through the control unit 4 during each winding process. S100 includes the following steps (1)～( 3).

(1) Take the images of the first anode pole piece 11' and the first cathode pole piece 12' respectively by the first photographing part 2 and the second photographing part 3 in the process of winding the i-th circle, and from the two images The first calibration pixel coordinates of the width edge of the first anode pole piece 11' and the second calibration pixel coordinates of the first cathode pole piece 12' are respectively obtained.

(2) Measure the first actual width of the first anode pole piece 11' and the second actual width of the first cathode pole piece 12' respectively.

(3) Calculate the first pixel equivalent according to the first calibrated pixel coordinates and the first actual width; and calculate the second pixel equivalent according to the second calibrated pixel coordinates and the second actual width.

2. Execute S100', after the step of calibrating the pixel equivalent, store the number of turns in the winding process of the reference electrode assembly 1' corresponding to the first pixel equivalent and the second pixel equivalent.

3. Start winding an electrode assembly 1 to be tested in the winding machine, and execute S120 and obtain pixel coordinates during each winding process. S120 includes:

In the process of winding the i-th circle of the electrode assembly 1 to be tested, an image of the second anode pole piece 11 of the electrode assembly 1 to be tested is taken, and the first pixel coordinates of the width edge of the second anode pole piece 11 are obtained from the image, and Taking an image of the second cathode pole piece 12 of the electrode assembly 1 to be tested, and obtaining the second pixel coordinates of the width edge of the second cathode pole piece 12 from the image.

4. After the electrode assembly 1 to be tested is wound, calculate the excess width Wi of each circle respectively. The specific calculation method is:

For each turn, the step S110 of obtaining pixel equivalent and S130 of calculating the excess width are sequentially executed by the control unit 4, so as to read the pixel equivalent parameter of the layer from the storage unit 6 and use it to calculate the excess width Wi.

5. Determine whether the difference between the maximum excess width and the minimum excess width of W1, W2,...,Wi, Wn of the electrode assembly 1 to be tested exceeds the preset deviation, and if it does not exceed, it is determined that the winding of the electrode assembly 1 to be tested is qualified , if it exceeds, it is determined that the winding of the electrode assembly 1 to be tested is unqualified.

Secondly, the present disclosure provides a wound electrode assembly measuring device. In the following embodiments, since some terms have been explained in detail in the subject of the wound electrode assembly measuring method, details will not be repeated here.

In some embodiments, as shown in Figures 5 and 12, the wound electrode assembly measurement device includes:

The first photographing part 2 is configured to photograph the image of the first anode pole piece 11' of the reference electrode assembly 1', or the image of the second anode pole piece 11 of the electrode assembly 1 to be tested;

The second photographing part 3 is configured to photograph the image of the first cathode pole piece 12' of the reference electrode assembly 1', or the image of the second cathode pole piece 12 of the electrode assembly 1 to be tested; and

The control unit 4 is configured to obtain the pixel equivalent parameters corresponding to the i-th circle of the reference electrode assembly 1', the pixel equivalent parameters include: the first pixel equivalent and the first pixel equivalent of the first anode pole piece 11' of the reference electrode assembly 1' The second pixel equivalent of the cathode pole piece 12'; and in the process of winding the i-th circle of the electrode assembly under test 1, an image of the second anode pole piece 11 of the electrode assembly under test 1 is obtained, and the second anode is obtained from the image The first pixel coordinates of the width edge of the pole piece 11, and obtain the image of the second cathode pole piece 12 of the electrode assembly 1 to be tested, obtain the second pixel coordinates of the width edge of the second cathode pole piece 12 from the image; then according to the reference electrode The first pixel equivalent and the second pixel equivalent of the i-th circle of the component 1', and the first pixel coordinates and the second pixel coordinates of the i-th circle of the electrode assembly 1 to be tested are used to calculate the second The excess width Wi of the anode pole piece 11 relative to the second cathode pole piece 12 along the winding axis K.

Wherein, the first photographing part 2 and the second photographing part 3 can be various cameras, taking the electrode assembly 1 to be tested as an example, the first photographing part 2 can use an infrared camera to pass through the second diaphragm 13 to photograph the On the second anode pole piece 11, the distance between the first photographing part 2 and the second anode pole piece 11 is S1; the second photographing part 3 can photograph the second cathode pole piece 12 to be wound on the winding shaft K , the distance between the second photographing component 3 and the second cathode sheet 12 is S2. S1 and S2 can be selected according to actual needs.

In this embodiment of the present application, the first pixel equivalent is respectively obtained for each circle of the first anode pole piece 11' in the reference electrode assembly 1', and the second pixel equivalent is respectively obtained for each circle of the first cathode pole piece 12', In the process of winding different circles of the electrode assembly 1 to be tested, the corresponding first pixel equivalent and second pixel equivalent can be used to calculate the excess width Wi of the circle, and the pixel equivalent can be automatically compensated by the algorithm. The change in the winding process can improve the calculation accuracy of the excess width Wi, thereby improving the performance, life and safety of the battery cell 10 .

In addition, the winding electrode assembly measurement method of the present application can reduce the requirements for the shooting accuracy of the first shooting part 2 and the second shooting part 3, and there is no need to select higher-precision shooting parts or take macro shots, and it is not necessary to set a driving mechanism to make the second shooting part 2 The movement of the first photographing part 2 and the second photographing part 3 saves space and is convenient for installation in a narrow space in the winding machine, thereby reducing costs.

In some embodiments, as shown in FIG. 5 , the first imaging component 2 and the second imaging component 3 are fixedly arranged on the same side of the winding axis K of the reference electrode assembly 1' or the electrode assembly 1 to be tested.

Wherein, in a plane perpendicular to the winding axis K, the first photographing part 2 and the second photographing part 3 can be arranged at different positions along the circumferential direction of the winding axis K, so that the first photographing part 2 and the second photographing part 3 Shooting with different angles to get the best shooting angle. In the extending direction of the winding axis K, the first photographing component 2 and the second photographing component 3 can be located at the same position, or they can also be staggered. In order to ensure the shooting effect, a supplementary light can also be set.

In this embodiment of the present application, the first photographing part 2 and the second photographing part 3 are arranged on the same side of the winding axis K, which can save the space occupied in the winding machine, facilitate installation, and facilitate the installation position of the photographing part Select the base line BL as the basis. In addition, the first photographing part 2 and the second photographing part 3 are fixedly arranged, and there is no need to set a driving mechanism to move the first photographing part 2 and the second photographing part 3, which can further save space and facilitate installation in a narrow space in the winding machine , thereby reducing costs.

In some embodiments, as shown in FIG. 14 , the control unit 4 includes: a calibration unit 41 configured to, according to the image of the first anode electrode piece 11 ′ and The actual size of the first anode pole piece 11' is marked with the first pixel equivalent of the i-th circle of the reference electrode assembly 1'; and according to the image of the first cathode pole piece 12' and the actual size of the first cathode pole piece 12', The second pixel equivalent of the i-th circle of the reference electrode assembly 1' is calibrated.

In some embodiments, as shown in FIG. 14 , the wound electrode assembly measuring device further includes: a measuring part 5 configured to measure the first actual width and the first anode pole piece 11' in the reference electrode assembly 1'. The second actual width of the cathode tab 12'.

Wherein, the calibration unit 41 is configured to acquire the image of the i-th circle of the first anode pole piece 11', and obtain the first calibration pixel coordinates of the width edge of the first anode pole piece 11' from the image, according to the first calibration pixel coordinates and First actual width, calculate the first pixel equivalent; and acquire the image of the i-th circle of the first cathode pole piece 12', and obtain the second calibration pixel coordinates of the width edge of the first cathode pole piece 12' from the image, according to the first 2. Calibrate the pixel coordinates and the second actual width to calculate the second pixel equivalent.

Wherein, the measuring component 5 may be a precision image mapping instrument, and the first actual width and the second actual width are both physical width dimensions.

This embodiment of the present application can obtain the pixel width dimensions of the first anode pole piece 11' and the first cathode pole piece 12' through images during the i-th circle winding process of the reference electrode assembly 1', and measure the first The physical width dimensions of the anode pole piece 11 ′ and the first cathode pole piece 12 ′ are used to calculate the first pixel equivalent and the second pixel equivalent. Since the overall width of the first anode pole piece 11' and the first cathode pole piece 12' is relatively large, the measurement of the physical width dimension and the acquisition of the pixel width dimension are more accurate, and the first pixel equivalent and the second pixel equivalent can be improved. Calibration accuracy.

In some embodiments, as shown in FIG. 14 , the device for measuring the wound electrode assembly further includes: a storage unit 6 configured to store the number of turns of the calibrated reference electrode assembly 1' during the winding process with the first pixel equivalent sum The second pixel equivalent corresponds to storage.

The "corresponding storage" here refers to storing according to the mapping relationship between the number of circles and the first pixel equivalent and the second pixel equivalent, that is, each circle corresponds to a first pixel equivalent and a second pixel equivalent. The corresponding relationship can be stored in the storage unit 6 for subsequent acquisition. The control unit 4 only needs to send the number of turns instruction to the storage unit 6 to obtain the first pixel equivalent and the second pixel equivalent corresponding to the number of turns through table lookup. For example, the storage unit 6 may be a magnetic disk, a flash memory or any other non-volatile storage medium.

In some embodiments, as shown in FIG. 14 , the control unit 4 includes: an alignment calculation unit 42 configured to, during the process of winding the i-th turn of the electrode assembly 1 , according to the i-th turn of the reference electrode assembly 1 ′ One pixel equivalent and the first pixel coordinates of the width edge of the second anode pole piece 11 of the i-th circle of the electrode assembly 1 to be tested obtain the first distance L1i between the width edge of the second anode pole piece 11 with respect to the reference line BL and according to the second pixel equivalent of the second cathode pole piece 12 width edge of the i-th circle of the reference electrode assembly 1' and the second pixel coordinates of the i-th circle of the electrode assembly to be tested, the width of the second cathode pole piece 12 is obtained The second distance L2i between the edge and the reference line BL; and then calculate the excess width Wi of the second anode pole piece 11 relative to the second cathode pole piece 12 according to the difference between the first distance L1i and the second distance L2i.

In some embodiments, the alignment calculation unit 42 is configured to sum the difference and the pre-acquired deviation adjustment value to calculate the excess width Wi of the second anode pole piece 11 relative to the second cathode pole piece 12.

The control unit 4, the calibration unit 41 and the alignment calculation unit 42 in the above-mentioned embodiment may be a general-purpose processor, a programmable logic controller (Programmable Logic Controller, referred to as: PLC), a digital signal for performing the functions described in the present disclosure. Processor (Digital Signal Processor, referred to as: DSP), application specific integrated circuit (Application Specific Integrated Circuit, referred to as: ASIC), field programmable gate array (Field-Programmable Gate Array, referred to as: FPGA) or other programmable logic devices, discrete Gate or transistor logic devices, discrete hardware components, or any suitable combination thereof.

While the application has been described with reference to a preferred embodiment, various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the application. In particular, as long as there is no structural conflict, the technical features mentioned in the various embodiments can be combined in any manner. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

A method for measuring a wound electrode assembly, comprising:

The step of obtaining pixel equivalent: obtaining the pixel equivalent parameter corresponding to the i-th circle around the reference electrode assembly (1'), the pixel equivalent parameter including: the first anode pole piece (11') of the reference electrode assembly (1') The first pixel equivalent of and the second pixel equivalent of the first cathode pole piece (12'), wherein, 1≤i≤n, and i is a natural number, and n is the total number of turns;

Step of obtaining pixel coordinates: during the process of winding the i-th circle of the electrode assembly (1) to be tested, take an image of the second anode pole piece (11) of the electrode assembly (1) to be tested, and obtain the The first pixel coordinates of the width edge of the second anode pole piece (11), and take an image of the second cathode pole piece (12) of the electrode assembly (1) to be tested, and obtain the second cathode pole piece from the image (12) The second pixel coordinates of the width edge;

Calculating the excess width step: according to the first pixel equivalent and the second pixel equivalent corresponding to the i-th circle of the reference electrode assembly (1'), and the i-th circle of the electrode assembly (1) to be tested The first pixel coordinates and the second pixel coordinates are used to calculate the edge of the second anode pole piece (11) relative to the second cathode pole piece (12) in the i-th circle of the electrode assembly (1) to be tested. The excess width Wi of the winding shaft (K).
The method for measuring a wound electrode assembly according to claim 1, further comprising:

Step of calibrating pixel equivalent: during the process of winding the i-th turn of the reference electrode assembly (1'), according to the image of the first anode pole piece (11') and the first anode pole piece (11') The actual size of the reference electrode assembly (1') is demarcated the first pixel equivalent of the i-th circle; and according to the image of the first cathode pole piece (12') and the first cathode pole piece (12' ) to demarcate the second pixel equivalent of the i-th circle of the reference electrode assembly (1').
The method for measuring wound electrode assemblies according to claim 2, wherein, according to the image of the first anode pole piece (11') and the actual size of the first anode pole piece (11'), the said The first pixel equivalent of the i-th circle of the reference electrode assembly (1') includes:

Obtain the image of the first anode pole piece (11') in the i-th circle, and obtain the first calibration pixel coordinates of the width edge of the first anode pole piece (11') from the image;

Measuring the first actual width of the first anode pole piece (11');

The first pixel equivalent is calculated according to the first calibrated pixel coordinates and the first actual width.
The method for measuring wound electrode assemblies according to claim 2 or 3, wherein, according to the image of the first cathode pole piece (12') and the actual size of the first cathode pole piece (12'), the The second pixel equivalent of the i-th circle of the reference electrode assembly (1') includes:

Obtain the image of the first cathode pole piece (12') in the i-th circle, and obtain the second calibration pixel coordinates of the width edge of the first cathode pole piece (12') from the image;

Measuring the second actual width of the first cathode pole piece (12');

The second pixel equivalent is calculated according to the second calibrated pixel coordinates and the second actual width.
The method for measuring a wound electrode assembly according to any one of claims 2 to 4, further comprising:

After the step of calibrating the pixel equivalent, the number of turns in the winding process of the reference electrode assembly (1') is stored in correspondence with the first pixel equivalent and the second pixel equivalent.
The method for measuring a wound electrode assembly according to any one of claims 1 to 5, wherein the step of calculating the excess width comprises:

According to the first pixel equivalent of the i-th circle of the reference electrode assembly (1') and the first pixel of the width edge of the second anode pole piece (11) of the i-th circle of the electrode assembly (1) to be tested coordinates to obtain the first distance L1i between the width edge of the second anode pole piece (11) relative to the reference line (BL);

According to the second pixel equivalent of the i-th circle of the reference electrode assembly (1') and the second pixel coordinates of the width edge of the second cathode pole piece (12) of the i-th circle of the electrode assembly (1) to be tested, obtaining a second distance L2i between the width edge of the second cathode pole piece (12) relative to the reference line (BL);

According to the difference between the first distance L1i and the second distance L2i, the excess width Wi of the i-th circle of the second anode pole piece (11) relative to the second cathode pole piece (12) is calculated.
The method for measuring wound electrode assemblies according to claim 6, wherein, according to the difference between the first distance L1i and the second distance L2i, the relative distance between the second anode pole piece (11) and the The excess width Wi of the second cathode pole piece (12) includes:

Obtain the deviation adjustment value in advance;

Summing the difference and the deviation adjustment value to calculate the excess width Wi of the second anode pole piece (11) relative to the second cathode pole piece (12).

Wherein, the first photographing part (2) is configured to photograph the image of the first anode pole piece (11') or the second anode pole piece (11), and the second photographing part (3) is It is configured to take an image of the first cathode pole piece (12') or an image of the second cathode pole piece (12).
The method for measuring a wound electrode assembly according to any one of claims 1 to 7, wherein, in the process of winding the electrode assembly (1) to be tested, the acquisition is performed sequentially from the first turn to the nth turn The step of pixel coordinates, and after all the steps of obtaining pixel coordinates are executed, the step of calculating the width beyond the width of each circle of the electrode assembly (1) to be tested is performed to obtain W1, W2,..., Wi, Wn;

The method for measuring the wound electrode assembly also includes:

In the case that the difference between the maximum excess width and the minimum excess width among W1, W2,..., Wi, Wn of the electrode assembly (1) to be tested does not exceed a preset deviation, it is judged that the electrode assembly to be tested ( 1) The winding is qualified.
A wound electrode assembly measuring device, comprising:

The first photographing part (2) is configured to photograph the image of the first anode pole piece (11') of the reference electrode assembly (1'), or the image of the second anode pole piece (11) of the electrode assembly (1) to be tested image;

The second photographing part (3) is configured to photograph the image of the first cathode pole piece (12') of the reference electrode assembly (1'), or the image of the second cathode pole piece (12) of the electrode assembly (1) to be tested images; and

The control part (4) is configured to obtain the pixel equivalent parameter corresponding to the i-th circle of the winding reference electrode assembly (1'), the pixel equivalent parameter including: the first anode electrode piece of the reference electrode assembly (1') The first pixel equivalent of (11') and the second pixel equivalent of the first cathode pole piece (12'); and in the process of winding the i-th circle of the electrode assembly (1) to be tested, the electrode assembly to be tested is obtained (1) the image of the second anode pole piece (11), obtain the first pixel coordinates of the width edge of the second anode pole piece (11) from the image, and obtain the first pixel coordinate of the electrode assembly (1) to be tested (1) The image of the two cathode pole pieces (12), obtain the second pixel coordinates of the width edge of the second cathode pole piece (12) from the image; A pixel equivalent and the second pixel equivalent, and the first pixel coordinate and the second pixel coordinate of the i-th circle of the electrode assembly (1) to be tested are used to calculate the electrode assembly (1) to be tested The excess width Wi of the second anode pole piece (11) relative to the second cathode pole piece (12) along the winding axis (K) in the i-th turn.
The winding electrode assembly measuring device according to claim 9, wherein, the first photographing part (2) and the second photographing part (3) are fixedly arranged on the reference electrode assembly (1') or the The same side as the winding axis (K) of the electrode assembly (1) to be tested.
The wound electrode assembly measuring device according to claim 9 or 10, wherein the control part (4) comprises:

A calibration unit (41), configured to, during the process of winding the i-th turn of the reference electrode assembly (1'), according to the image of the first anode pole piece (11') and the first anode pole piece The actual size of (11') marks the first pixel equivalent of the i-th circle of the reference electrode assembly (1'); and according to the image of the first cathode sheet (12') and the first cathode electrode The actual size of the sheet (12') marks the second pixel equivalent of the i-th circle of the reference electrode assembly (1').
The wound electrode assembly measuring device according to claim 11, further comprising:

A measuring part (5), configured to measure the first actual width of the first anode pole piece (11') and the first actual width of the first cathode pole piece (12') in the reference electrode assembly (1'). 2 actual width;

Wherein, the calibration unit (41) is configured to acquire the image of the i-th circle of the first anode pole piece (11'), and obtain the first anode pole piece (11') width edge of the first anode pole piece (11') from the image A calibrated pixel coordinate, calculating the first pixel equivalent according to the first calibrated pixel coordinate and the first actual width; and acquiring an image of the i-th circle of the first cathode pole piece (12'), and The second marked pixel coordinates of the width edge of the first cathode electrode piece (12') are obtained from the image, and the second pixel equivalent is calculated according to the second marked pixel coordinates and the second actual width.
The wound electrode assembly measuring device according to claim 11 or 12, further comprising:

The storage unit (6) is configured to store the calibrated number of turns in the winding process of the reference electrode assembly (1') corresponding to the first pixel equivalent and the second pixel equivalent.
The device for measuring wound electrode assemblies according to any one of claims 9-13, wherein the control component (4) includes:

The alignment calculation unit (42) is configured to, during the process of winding the i-th turn of the electrode assembly (1), according to the first pixel equivalent and the The first pixel coordinates of the width edge of the second anode pole piece (11) of the i-th circle of the electrode assembly to be tested (1), draw the width edge of the second anode pole piece (11) relative to the reference line ( BL) between the first distance L1i; and according to the second pixel equivalent of the i-th circle of the reference electrode assembly (1') and the second cathode pole piece of the i-th circle of the electrode assembly (1) to be tested (12) The second pixel coordinates of the width edge obtain the second distance L2i between the width edge of the second cathode pole piece (12) relative to the reference line (BL); then according to the first distance The difference between L1i and the second distance L2i calculates the excess width Wi of the second anode pole piece (11) relative to the second cathode pole piece (12).
The device for measuring the wound electrode assembly according to claim 14, wherein the alignment calculation unit (42) is configured to sum the difference value and a pre-acquired deviation adjustment value to calculate the second anode The excess width Wi of the pole piece (11) relative to the second cathode pole piece (12).