CN116670885A

CN116670885A - Coiled electrode assembly measuring method and device

Info

Publication number: CN116670885A
Application number: CN202180083170.9A
Authority: CN
Inventors: 谢金潭; 陈继伟; 王绪明
Original assignee: Contemporary Amperex Technology Co Ltd
Current assignee: Contemporary Amperex Technology Co Ltd
Priority date: 2021-09-01
Filing date: 2021-09-01
Publication date: 2023-08-29
Also published as: WO2023028923A1

Abstract

A method and apparatus for measuring a wound electrode assembly (102), wherein the method for measuring comprises: acquiring a pixel equivalent parameter corresponding to the ith turn of the coiled reference electrode assembly (1'), comprising: referring to a first pixel equivalent of a first anode electrode sheet (11 ') and a second pixel equivalent of a first cathode electrode sheet (12 ') of the electrode assembly (1 '); in the process of winding the ith circle of the electrode assembly (1) to be measured, shooting an image of a second anode pole piece (11) of the electrode assembly (1) to be measured, obtaining a first pixel coordinate of the width edge of the second anode pole piece (11) from the image, shooting an image of a second cathode pole piece (12) of the electrode assembly (1) to be measured, and obtaining a second pixel coordinate of the width edge of the second cathode pole piece (12) from the image; according to the first pixel equivalent and the second pixel equivalent corresponding to the ith circle of the reference electrode assembly (1') and the first pixel coordinate and the second pixel coordinate of the ith circle of the electrode assembly (1) to be detected, calculating the exceeding width Wi of the second anode pole piece (11) in the ith circle of the electrode assembly (1) to be detected relative to the second cathode pole piece (12) along the winding axis (K).

Description

Coiled electrode assembly measuring method and device

Technical Field

The application relates to the technical field of batteries, in particular to a method and a device for measuring a winding electrode assembly.

Background

With the advantages of high energy density, high power density, multiple recycling times, long storage time and the like of batteries such as lithium ions, the lithium ion battery has been widely applied to electric automobiles.

In the production process of lithium batteries, an anode pole piece, a cathode pole piece and a diaphragm are required to be wound into a battery core. This procedure has various standard requirements for the pole pieces during winding, one of the important requirements being that the width dimension of the anode pole pieces beyond the cathode pole pieces remain consistent during winding, i.e. the degree of alignment of the anode pole pieces with the cathode pole pieces in the width direction. The accuracy of detection of this parameter directly affects the performance of the battery, but improving the accuracy of detection of this parameter has been a problem in the industry.

Disclosure of Invention

The application aims to improve the performance of a battery.

According to a first aspect of the present application, there is provided a wound electrode assembly measurement method comprising:

a step of acquiring pixel equivalent: obtaining a pixel equivalent parameter corresponding to the ith turn of the coiled reference electrode assembly, wherein the pixel equivalent parameter comprises: referring to a first pixel equivalent of a first anode pole piece and a second pixel equivalent of a first cathode pole piece of the electrode assembly, i is more than or equal to 1 and less than or equal to n, wherein i is a natural number, and n is a total number of turns;

Acquiring pixel coordinates: in the process of winding the ith circle of the electrode assembly to be measured, shooting an image of a second anode pole piece of the electrode assembly to be measured, obtaining a first pixel coordinate of the width edge of the second anode pole piece from the image, shooting an image of a second cathode pole piece of the electrode assembly to be measured, and obtaining a second pixel coordinate of the width edge of the second cathode pole piece from the image;

calculating the excess width: and calculating the exceeding width Wi of the second anode pole piece in the ith circle of the electrode assembly to be measured relative to the second cathode pole piece along the winding shaft according to the first pixel equivalent and the second pixel equivalent corresponding to the ith circle of the reference electrode assembly and the first pixel coordinate and the second pixel coordinate of the ith circle of the electrode assembly to be measured.

According to the embodiment of the 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, so that the exceeding width Wi of the circle can be calculated by adopting the corresponding first pixel equivalent and second pixel equivalent in the process of winding different circles of the electrode assembly to be detected, the change of the pixel equivalent in the process of winding the electrode assembly to be detected can be automatically compensated through an algorithm, and the calculation accuracy of the exceeding width Wi can be improved.

Through improving the calculation accuracy beyond width Wi, the alignment degree of a second anode pole piece and a second cathode pole piece in the electrode assembly to be detected along a winding shaft can be improved, so that lithium ions are easier to be embedded into an anode active material area of the second anode pole piece, the phenomenon of lithium separation is prevented, cathode active materials on the second cathode pole piece fully play a role, the performance of a battery monomer is improved, the cycle life and the quick charge capacity of the battery monomer are improved, and the safety problems such as combustion, explosion and the like can be reduced.

In addition, the measuring method of the winding electrode assembly can reduce the requirement of the shooting precision of the first shooting part and the second shooting part, does not need to select shooting parts with higher precision, does not need to arrange a driving mechanism to enable the first shooting part and the second shooting part to move, saves space, and is convenient to install in a narrow space in a winding machine, so that the cost can be reduced.

In some embodiments, the coiled electrode assembly measurement method further comprises:

calibrating pixel equivalent: in the process of winding the ith circle of the reference electrode assembly, calibrating a first pixel equivalent of the ith 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; and calibrating a second pixel equivalent of the ith circle of the reference electrode assembly according to the image of the first cathode plate and the actual size of the first cathode plate.

According to the embodiment of the application, the first pixel equivalent and the second pixel equivalent of each circle can be calibrated in advance in the process of winding the reference electrode assembly, and the pre-calibrated pixel equivalent parameters can be adopted in the subsequent process of winding the electrode assembly to be tested, so that the change of the pixel equivalent in the winding process of the electrode assembly to be tested can be automatically compensated, the calculation accuracy exceeding the width Wi is improved, and the performance, the service life and the safety of the battery cell are further improved.

In some embodiments, calibrating the first pixel equivalent of the i-th turn of the reference electrode assembly based on the image of the first anode electrode sheet and the actual size of the first anode electrode sheet comprises:

acquiring an image of a first anode pole piece of an ith circle, and obtaining a first calibration pixel coordinate of the width edge of the first anode pole piece from the image;

measuring a first actual width of the first anode sheet;

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

This embodiment of the present application is capable of obtaining a pixel width dimension of the first anode electrode sheet through an image and measuring a physical width dimension of the first anode electrode sheet in the process of winding the i-th turn of the reference electrode assembly, thereby calculating the first pixel equivalent. Because the whole width of the first anode plate is relatively larger, 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. Alternatively, the first pixel equivalent may also be scaled based on the excess width Wi portion.

In some embodiments, calibrating the second pixel equivalent of the i-th turn of the reference electrode assembly based on the image of the first cathode electrode sheet and the actual size of the first cathode electrode sheet comprises:

acquiring an image of the ith circle of first cathode pole piece, and obtaining a second calibration pixel coordinate of the width edge of the first cathode pole piece from the image;

measuring a second actual width of the first cathode sheet;

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

This embodiment of the present application can obtain the pixel width dimension of the first cathode electrode sheet through an image during the i-th turn of the winding reference electrode assembly and measure the physical width dimension of the first cathode electrode sheet, thereby calculating the second pixel equivalent. Because the whole width of the first cathode plate 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 of the reference electrode assembly during winding is stored in correspondence with the first pixel equivalent and the second pixel equivalent.

In the embodiment, after the pixel equivalent parameter of each circle of the reference electrode assembly is calibrated, the pixel equivalent parameter of each circle is stored according to the corresponding relation with the circle number, so that the pixel equivalent parameter of each circle is conveniently called when the excess width Wi is calculated, and the excess width Wi corresponding to each circle of the electrode assembly to be measured is calculated efficiently.

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

obtaining a first distance L1i between the width edge of the second anode pole piece and the reference line according to the first pixel equivalent of the ith circle of the reference electrode assembly and the first pixel coordinate of the width edge of the second anode pole piece of the ith circle of the electrode assembly to be detected;

obtaining a second distance Li between the width edge of the second cathode pole piece relative to the datum line according to the second pixel equivalent of the ith circle of the reference electrode assembly and the second pixel coordinate of the width edge of the second cathode pole piece of the ith circle of the electrode assembly to be detected;

and calculating the exceeding width Wi of the ith circle of second anode pole piece relative to the second cathode pole piece according to the difference value of the first distance L1i and the second distance Li.

According to the embodiment of the application, the exceeding width Wi of the second anode pole piece of the ith circle relative to the second cathode pole piece can be obtained based on the corresponding pixel equivalent parameter of each i circle in the reference electrode assembly, and the exceeding width Wi can be accurately and conveniently calculated, so that the performance, the service life and the safety of the battery cell are improved.

In some embodiments, calculating the excess width Wi of the second anode electrode sheet relative to the second cathode electrode sheet based on the difference between the first distance L1i and the second distance Li comprises:

acquiring a deviation adjusting value in advance;

and summing the difference value and the deviation adjustment value, and calculating the exceeding width Wi of the second anode pole piece relative to the second cathode pole piece.

In the embodiment of the application, the deviation adjustment value is introduced to allow the central lines of the images shot by the first shooting component and the second shooting component to coincide so as to unify the references for obtaining the first pixel coordinate and the second pixel coordinate and improve the accuracy of the calculation result in consideration of the deviation of the actual physical positions of the first shooting component and the second shooting component in the winding axis direction.

In some embodiments, in the process of winding the electrode assembly to be measured, the step of acquiring the pixel coordinates is sequentially performed from the 1 st turn to the nth turn, and after all the steps of acquiring the pixel coordinates are performed, the step of calculating the excess width is performed for each turn of the electrode assembly to be measured, so as to obtain W1, W, …, wi, wn;

the wound electrode assembly measurement method further includes:

and when the difference between the maximum exceeding width and the minimum exceeding width in the W1, W, … of the electrode assembly to be tested is not more than the preset deviation, judging that the electrode assembly to be tested is qualified in winding.

According to the embodiment of the application, after the electrode assembly to be measured is wound, the exceeding width Wi of each circle is calculated respectively, so that whether the electrode assembly to be measured is wound is qualified or not is judged. In addition, the method can enable the whole winding process of the electrode assembly to be measured to be more continuous, keep the tension of the pole piece uniform in the winding process, and improve the winding efficiency.

According to a second aspect of the present application, there is provided a wound electrode assembly measuring apparatus comprising:

a first photographing part configured to photograph an image of a first anode tab of a reference electrode assembly or an image of a second anode tab of an electrode assembly to be measured;

a second photographing part configured to photograph an image of a first cathode tab of the reference electrode assembly or an image of a second cathode tab of the electrode assembly to be measured; and

a control part configured to acquire a pixel equivalent parameter corresponding to an i-th turn of the winding reference electrode assembly, the pixel equivalent parameter including: referring to a first pixel equivalent of a first anode electrode sheet and a second pixel equivalent of a first cathode electrode sheet of the electrode assembly; in the process of winding the ith circle of the electrode assembly to be measured, acquiring an image of a second anode pole piece of the electrode assembly to be measured, acquiring a first pixel coordinate of the width edge of the second anode pole piece from the image, acquiring an image of a second cathode pole piece of the electrode assembly to be measured, and acquiring a second pixel coordinate of the width edge of the second cathode pole piece from the image; and calculating the exceeding width Wi of the second anode pole piece in the ith circle of the electrode assembly to be measured relative to the second cathode pole piece along the winding shaft according to the first pixel equivalent and the second pixel equivalent of the ith circle of the reference electrode assembly and the first pixel coordinate and the second pixel coordinate of the ith circle of the electrode assembly to be measured.

According to the embodiment of the 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, so that the exceeding width Wi of the circle can be calculated by adopting the corresponding first pixel equivalent and second pixel equivalent in the process of winding different circles of the electrode assembly to be detected, the change of the pixel equivalent in the winding process of the electrode assembly to be detected can be automatically compensated through an algorithm, the calculation precision of the exceeding width Wi can be improved, and the performance, the service life and the safety of a battery cell are improved.

In addition, the measuring method of the winding electrode assembly can reduce the requirement on the shooting precision of the first shooting part and the second shooting part, does not need to select a shooting part with higher precision or shoot with a micro distance, does not need to arrange a driving mechanism to enable the first shooting part and the second shooting part to move, saves space, and is convenient to install in a narrow space in a winding machine, so that the cost can be reduced.

In some embodiments, the first photographing part and the second photographing part are fixedly disposed at the same side of the winding shaft of the reference electrode assembly or the electrode assembly to be measured.

According to the embodiment of the application, the first shooting component and the second shooting component are arranged on the same side of the winding shaft, so that the space occupied in the winding machine can be saved, the installation is convenient, and the reference line can be conveniently selected based on the installation position of the shooting components. In addition, the first shooting part and the second shooting part are fixedly arranged, a driving mechanism is not required to be arranged to enable the first shooting part and the second shooting part to move, space can be further saved, installation in a narrow space in a winding machine is facilitated, and therefore cost can be reduced.

In some embodiments, the control component comprises:

a calibration unit configured to calibrate a first pixel equivalent of the ith turn of the reference electrode assembly according to the image of the first anode electrode sheet and the actual size of the first anode electrode sheet in the process of winding the ith turn of the reference electrode assembly; and calibrating a second pixel equivalent of the ith circle of the reference electrode assembly according to the image of the first cathode plate and the actual size of the first cathode plate.

In some embodiments, the coiled electrode assembly measurement device further comprises:

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

the calibration unit is configured to acquire an image of the ith circle of first anode pole piece, obtain a first calibration pixel coordinate of the width edge of the first anode pole piece from the image, and calculate a first pixel equivalent according to the first calibration pixel coordinate and a first actual width; and acquiring an image of the first cathode pole piece of the ith circle, obtaining second calibration pixel coordinates of the width edge of the first cathode pole piece from the image, and calculating second pixel equivalent according to the second calibration pixel coordinates and the second actual width.

The embodiment of the application can obtain the pixel width sizes of the first anode pole piece and the first cathode pole piece through images in the process of winding the ith turn of the reference electrode assembly, and measure the physical width sizes of the first anode pole piece and the first cathode pole piece, thereby calculating the first pixel equivalent and the second pixel equivalent. Because the whole width of the first anode pole piece and the first cathode pole piece is relatively larger, 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.

and a storage part configured to store the number of turns of the calibrated reference electrode assembly during winding in correspondence with the first pixel equivalent and the second pixel equivalent.

In some embodiments, the control component comprises:

An alignment degree calculating unit configured to obtain a first distance L1i between the width edge of the second anode electrode sheet and the reference line according to a first pixel equivalent of the i-th turn of the reference electrode assembly and a first pixel coordinate of the width edge of the second anode electrode sheet of the i-th turn of the electrode assembly to be measured in the process of winding the i-th turn of the electrode assembly; obtaining a second distance Li between the width edge of the second cathode pole piece relative to the datum line according to a second pixel equivalent of the ith circle of the reference electrode assembly and a second pixel coordinate of the width edge of the second cathode pole piece of the ith circle of the electrode assembly to be detected; and then, calculating the exceeding width Wi of the second anode pole piece relative to the second cathode pole piece according to the difference value of the first distance L1i and the second distance Li.

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

In the embodiment of the application, the deviation adjusting value is introduced to allow the central lines of the images shot by the first shooting component and the second shooting component to coincide so as to unify the references for obtaining the first pixel coordinate and the second pixel coordinate and improve the accuracy of the calculation result in consideration of the deviation of the actual physical positions of the first shooting component and the second shooting component in the winding axis direction.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments of the present application will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present application, and other drawings may be obtained according to the drawings without inventive effort for a person skilled in the art.

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

Fig. 2 is a schematic view of some embodiments of the electrode assembly of fig. 1 prior to winding.

Fig. 3 is an enlarged view at a of fig. 2.

Fig. 4 is a schematic view of some embodiments of the electrode assembly of fig. 1 after being wound.

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

FIG. 6 is a schematic illustration of the dimensions of a second anode electrode sheet in an electrode assembly to be tested along a winding axis beyond the second cathode electrode sheet;

fig. 7 is a flow chart of some embodiments of a coiled electrode assembly measurement method of the present application.

Fig. 8 is a flow chart of another embodiment of a method for measuring a wound electrode assembly according to the present application.

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

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

Fig. 11 is a flow chart of still another embodiment of the measuring method of the wound electrode assembly of the present application.

FIG. 12 is a flow chart of some embodiments of the step of calculating the excess width.

Fig. 13 is a schematic block diagram of some embodiments of a coiled electrode assembly measuring device according to the present application.

Fig. 14 is a schematic block diagram showing another embodiment of a measuring apparatus for a rolled electrode assembly according to the present application.

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

Reference numerals in the specific embodiments are as follows:

10. a battery cell; 101. a housing; 102. an electrode assembly; 103. an adapter; 104. an end cap assembly; 104A, an end cap body; 104B, positive terminal; 104C, a negative terminal; 104D, a pressure relief component;

1', a reference electrode assembly; 11', a first anode pole piece; 12', a first cathode sheet; 13', a first separator; K. a winding shaft; BL, datum line;

1. an electrode assembly to be tested; 11. a second anode sheet; 12. a second cathode sheet; 13. a second diaphragm;

2. a first photographing part; 3. a second photographing part; 4. a control part; 41. a calibration unit; 42. an alignment degree calculation unit; 5. a measuring part; 6. a storage unit.

Detailed Description

Embodiments of the present application are described in further detail below with reference to the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are provided to illustrate the principles of the application and are not intended to limit the scope of the application, i.e., the application is not limited to the embodiments described.

In the description of the present application, it is to be noted that, unless otherwise indicated, the meaning of "plurality" is two or more; the terms "upper," "lower," "left," "right," "inner," "outer," and the like are merely used for convenience in describing the present application and to simplify the description, and do not denote or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus are not to be construed as limiting the present application.

Furthermore, the terms "first," "second," "third," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. The "vertical" is not strictly vertical but is within the allowable error range. "parallel" is not strictly parallel but is within the tolerance of the error. The directional terms appearing in the following description are those directions shown in the drawings and do not limit the specific structure of the application.

In the description of the present application, it should also be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be directly connected or indirectly connected through an intermediate medium. The specific meaning of the above terms in the present application can be understood as appropriate by those of ordinary skill in the art.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearances of such phrases 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. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.

In describing embodiments of the present application, the term "plurality" refers to more than two (including two), and similarly,

"multiple sets" refers to more than two sets (including two sets) and "multiple sheets" refers to more than two sheets (including two sheets).

In the description of the embodiments of the present application, the orientation or positional relationship indicated by the technical terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. are based on the orientation or positional relationship shown in the drawings, and are merely for convenience of description and simplification of the description, and do not indicate or imply that the apparatus or element referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the embodiments of the present application.

Currently, the application of power batteries is more widespread from the development of market situation. The power battery is not only applied to energy storage power supply systems such as hydraulic power, firepower, wind power and solar power stations, but also widely applied to electric vehicles such as electric bicycles, electric motorcycles, electric automobiles, and the like, and a plurality of fields such as military equipment, aerospace, and the like. With the continuous expansion of the application field of the power battery, the market demand of the power battery is also continuously expanding.

In the use process of the battery, the problems of easy performance reduction and easy cycle life shortening exist, and even in some cases, the safety exists. Those skilled in the art have attempted to solve this problem from many different angles for many years, but have not achieved the intended effect.

As part of the inventive process of the present application, the inventors have undergone numerous experiments and verifications and analysis of the electrode assembly in the battery, and found that one of the causes of the above problems in the battery is: the width dimension of the anode pole piece exceeding the cathode pole piece in the electrode assembly cannot be kept consistent in the winding process, namely the alignment precision of the anode pole piece and the cathode pole piece in the width direction is lower. The existence of the problem can make lithium ions difficult to be inserted into an anode active material area of an anode pole piece to cause a lithium ion separation phenomenon, and cathode active materials of a cathode pole piece are difficult to fully play a role, so that the performance of a battery is influenced, the cycle life of the battery is also greatly shortened, the quick charge capacity of the battery is limited, and safety problems such as combustion, explosion and the like can be caused.

In order to solve the problem, images of the anode and cathode electrode sheets are photographed by two photographing parts, respectively, by a preset distance during the winding of the electrode assembly, so as to calculate the exceeding width of the anode electrode sheet relative to the cathode electrode sheet according to the images.

However, the inventors have noted that the calculated value of the above-described width dimension depends on the pixel equivalent of the photographing section, which is the actual physical dimension represented by one pixel point in the image. However, as the pole pieces are continuously wound, the electrode assembly becomes thicker, the distance between the two photographing components and the corresponding pole pieces is dynamically changed, and the pixel equivalent is dynamically changed due to the fact that the photographing components are in a 'near-large-far-small' state, and if the fixed pixel equivalent is adopted to calculate the excess width, the excess width calculation is caused to generate errors.

In order to compensate the problem that the pixel equivalent changes due to the change of the distance between the shooting component and the pole piece, if the shooting component is moved by the driving mechanism in the winding process, so that the distance between the shooting component and the pole piece always keeps the optimal shooting focal length value, the mode also faces a plurality of problems in the practical application process, for example, the internal space of the winding machine is narrow, an extra space is difficult to leave, the control precision requirement on the driving mechanism is high, and the driving mechanism is difficult to maintain and has high cost.

Based on the above consideration, the inventor has made intensive studies to propose a concept of performing layered calibration on an electrode assembly, and has designed a measuring method of a wound electrode assembly based on the concept, comprising: a step of acquiring pixel equivalent, a step of acquiring pixel coordinates and a step of calculating the excess width.

Wherein, the step of obtaining pixel equivalent comprises the following steps: obtaining a pixel equivalent parameter corresponding to the ith turn of the coiled reference electrode assembly, wherein the pixel equivalent parameter comprises: referring to the first pixel equivalent of the first anode pole piece and the second pixel equivalent of the first cathode pole piece of the electrode assembly, i is more than or equal to 1 and less than or equal to n, wherein i is a natural number, and n is the total number of turns.

According to the measuring method of the winding electrode assembly, the first pixel equivalent is respectively obtained for each circle of the first anode pole piece in the reference electrode assembly, the second pixel equivalent is respectively obtained for each circle of the first cathode pole piece, the exceeding width Wi can be calculated by adopting the corresponding first pixel equivalent and second pixel equivalent in the process of winding the electrode assembly to be measured for different circles, the change of the pixel equivalent in the winding process of the electrode assembly can be automatically compensated through an algorithm, and the calculating precision of the exceeding width Wi can be improved, so that the performance, the service life and the safety of the battery are improved. In addition, the requirement on the shooting precision of the shooting component can be reduced, a driving mechanism is not required to be arranged to enable the shooting component to move, the shooting component is convenient to install in a winding machine, and the cost can be reduced.

In order to more clearly explain the measuring method of the wound electrode assembly of the present application, as shown in fig. 1, the structure of the minimum unit cell 10 in the battery will be first described.

The battery cell 10 includes a case 101, an electrode assembly 102, and an end cap assembly 104, the end cap assembly 104 is connected with the case 101 to form a housing of the battery cell 10, the electrode assembly 102 is disposed in the case 101, and the case 101 is filled with an electrolyte. The battery cell 10 may be square, cylindrical or other shape.

An end cap assembly 104 is provided atop the electrode assembly 102, the end cap assembly 104 including an end cap body 104A, a positive terminal 104B, a negative terminal 104C, and a pressure relief member 104D. Wherein, the positive terminal 104B and the negative terminal 104C are respectively provided with a adaptor 103, and the adaptor 103 is located between the end cover body 104A and the electrode assembly 102. For example, in fig. 1, tab 102A of electrode assembly 102 is positioned on top, the cathode tab is connected to positive terminal 104B by one adapter 103, and the anode tab is connected to negative terminal 104C by another adapter 103. A pressure relief member 104D is provided to the end cap body 104A and is configured to be actuated to relieve the internal pressure of the battery cell 10 when the internal pressure of the battery cell 10 reaches a threshold value.

The electrode assembly 102 may be provided in a single or in a plurality according to actual use requirements. As shown in fig. 1, at least two independently wound electrode assemblies 102 may also be provided within the battery cell 10. The electrode assembly 102 is required to measure the excess width Wi of the anode electrode sheet relative to the cathode electrode sheet during the winding process, and is therefore referred to as an electrode assembly 1 to be measured, while the standard electrode assembly used to obtain the pixel equivalent parameter is referred to as a reference electrode assembly 1', which is a normally manufactured and qualified electrode assembly for winding used to obtain the pixel equivalent parameter, and in fact, the electrode assembly 1 to be measured has the same structure as the reference electrode assembly 1', and is given different names and reference numerals for convenience of description only.

As shown in fig. 2 and 3, the reference electrode assembly 1 'may be formed by winding a first anode electrode sheet 11', a first cathode electrode sheet 12', and a first separator 13' for separating the first anode electrode sheet 11 'and the first cathode electrode sheet 12' together, as shown in fig. 4. For example, before winding, the first separator 13', the first anode electrode sheet 11', the first separator 13', and the first cathode electrode sheet 12' may be stacked in this order from bottom to top, with the first separator 13' being an insulator interposed between the first anode electrode sheet 11' and the first cathode electrode sheet 12 '. Wherein the first anode sheet 11' may be coated with an anode active material such as graphite or silicon; the first cathode sheet 12' may be coated with a cathode active material such as a ternary material, lithium manganate or lithium iron phosphate. After winding, the reference electrode assembly 1' may have a flat structure as shown in fig. 4, or may have a circular structure as shown in fig. 5.

Similarly, the electrode assembly 1 to be measured may be formed into a rolled electrode assembly by rolling the second anode electrode sheet 11, the second cathode electrode sheet 12, and the second separator 13 for separating the second anode electrode sheet 11 and the second cathode electrode sheet 12 together.

As shown in fig. 5, taking the electrode assembly 1 to be measured as an example, the second anode sheet 11, the second cathode sheet 12, and the second separator 13, which are stacked, extend into the winder and are wound around the winding shaft K at a winding station where the electrode assembly 1 to be measured is wound, and the first photographing part 2 and the second photographing part 3 are provided on the same side of the winding shaft K, and for example, the photographing parts may be various cameras. In order to obtain clear images, the first photographing part 2 and the second photographing part 3 may employ different photographing angles. Optionally, a reference electrode assembly 1 'may also be provided on the winding station to obtain pixel equivalent parameters during winding of the reference electrode assembly 1'.

The first photographing part 2 is configured to photograph an image of the second anode electrode sheet 11 of the electrode assembly 1 to be measured, and in particular, the second anode electrode sheet 11 wound on the winding shaft K may be photographed through the second separator 13 using an infrared camera, and the distance between the first photographing part 2 and the second anode electrode sheet 11 is S1.

The second photographing part 3 is configured to photograph an image of the second cathode sheet 12 of the electrode assembly 1 to be measured, in particular, the second cathode sheet 12 to be wound onto the winding shaft K may be photographed, and a distance between the second photographing part 3 and the second cathode sheet 12 is S2.

As shown in fig. 6, in winding the electrode assembly 1 to be measured in the ith turn, it is necessary to have the second anode electrode sheet 11 with respect to the second cathode electrode sheet 12 to have an excess width Wi on both sides along the winding axis K. The method and apparatus for measuring the excess width Wi are described in detail below in connection with fig. 7-14.

In some embodiments, as shown in fig. 7, the wound electrode assembly measurement method of the present disclosure includes:

s110, acquiring pixel equivalent: obtaining pixel equivalent parameters corresponding to the ith circle of the winding reference electrode assembly 1', wherein the pixel equivalent parameters comprise: referring to the first pixel equivalent of the first anode electrode sheet 11' and the second pixel equivalent of the first cathode electrode sheet 12' of the electrode assembly 1', wherein i is 1.ltoreq.n, and i is a natural number, n is the total number of turns.

S120, acquiring pixel coordinates: in the process of winding the ith circle of the electrode assembly 1 to be measured, an image of the second anode electrode plate 11 of the electrode assembly 1 to be measured is shot, a first pixel coordinate of the width edge of the second anode electrode plate 11 is obtained from the image, an image of the second cathode electrode plate 12 of the electrode assembly 1 to be measured is shot, and a second pixel coordinate of the width edge of the second cathode electrode plate 12 is obtained from the image.

S130, calculating an excess width: and calculating the exceeding width Wi of the second anode pole piece 11 in the ith circle of the electrode assembly 1 to be measured along the winding axis K relative to the second cathode pole piece 12 according to the first pixel equivalent and the second pixel equivalent corresponding to the ith circle of the reference electrode assembly 1' and the first pixel coordinate and the second pixel coordinate of the ith circle of the electrode assembly 1 to be measured.

In S101, it is assumed that the pixel equivalent parameter corresponding to the i-th turn of the wound reference electrode assembly 1' has been obtained by calibration or other methods, stored in the storage section 6, and the pixel equivalent parameter is acquired from the storage section 6 by the control section 4 before the excess width Wi is calculated.

For example, if the excess width Wi of each turn is calculated after the electrode assembly 1 to be measured is wound, the pixel equivalent parameters of the 1 st to n th turns may be obtained at one time before, during or after the winding of the electrode assembly 1 to be measured; if the excess width Wi of the ith turn is calculated after the completion of the winding of the ith turn, the pixel equivalent parameter of the ith turn may be obtained before the winding of the electrode assembly 1 to be measured, before the winding of the ith turn is started, or during the winding of the ith turn.

The reference electrode assembly 1' is a standard electrode assembly fabricated to obtain a pixel equivalent parameter, and the pixel equivalent is the actual physical size represented by one pixel point in the image. The pixel equivalent parameters include: reference is made to a first pixel equivalent of the first anode electrode sheet 11' and a second pixel equivalent of the first cathode electrode sheet 12' of the electrode assembly 1 '. The first pixel equivalent of the first anode electrode sheet 11' of the 1 st to n th turns in the reference electrode assembly 1' is different, and the second pixel equivalent of the first cathode electrode sheet 12' of the 1 st to n th turns is different. Thus, when calculating the excess width Wi of the ith turn, the variation in the photographing distance during winding can be compensated by the adjustment of the pixel equivalent parameter for each turn.

In S120, during the process of winding the electrode assembly 1 to be measured in the ith turn, the images of the second anode electrode tab 11 and the second cathode electrode tab 12 are photographed by the first photographing part 2 and the second photographing part 3, respectively, and the images may be numbered and named by the number of turns. Next, the first pixel coordinates of the width edge of the second anode electrode tab 11 and the second pixel coordinates of the width edge of the second cathode electrode tab 12 are obtained from the image. Wherein the first pixel coordinates represent the position of the width edge of the second anode electrode sheet 11 in the image and the second pixel coordinates represent the position of the width edge of the second cathode electrode sheet 12 in the image.

In S130, referring to fig. 6, the length between the two broken lines represents one winding of the pole piece, and in calculating the excess width Wi of the i-th winding of the electrode assembly 1 to be measured, the basic principle adopted is that the pixel equivalent times the pixel coordinate is equal to the actual physical size. As shown in fig. 6, the second anode electrode sheet 11 may exceed the second cathode electrode sheet 12 on both sides along the winding axis K, and the exceeding width Wi of both sides may be the same or different for the i-th turn.

Specifically, the actual physical position of the width edge of the second anode electrode piece 11 can be obtained by multiplying the first pixel equivalent corresponding to the ith circle of the electrode assembly 1' by the first pixel coordinate of the width edge of the second anode electrode piece 11 in the ith circle of the electrode assembly 1 to be measured; the actual physical position of the width edge of the second cathode electrode sheet 12 can be obtained by multiplying the second pixel equivalent corresponding to the ith turn of the electrode assembly 1' by the second pixel coordinate of the width edge of the second cathode electrode sheet 12 in the ith turn of the electrode assembly 1 to be measured, and thus, the exceeding width Wi of the second anode electrode sheet 11 in the ith turn of the electrode assembly 1 to be measured relative to the second cathode electrode sheet 12 along the winding axis K can be calculated. The winding axis K corresponds to the width direction of the second anode electrode sheet 11 or the second cathode electrode sheet 12.

The execution sequence of the steps in this embodiment is as follows: if the excess width Wi of each turn is calculated after the electrode assembly 1 to be measured is wound, S120 is performed once for each turn to obtain an image of each turn during the winding process, S130 is uniformly performed for each turn after the electrode assembly 1 to be measured is wound, and S110 corresponding to each turn may be uniformly performed before the electrode assembly 1 to be measured is wound, or performed during the winding process, or performed before S130 is performed after the winding process is completed. If the excess width Wi of the turn is calculated after the completion of the winding of the i-th turn, then S110, S120 and S130 may be sequentially performed for the i-th turn.

According to the embodiment of the 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', so that the exceeding width Wi of the circle can be calculated by adopting the corresponding first pixel equivalent and second pixel equivalent in the process of winding the electrode assembly 1 to be measured in different circles, the change of the pixel equivalent in the winding process of the electrode assembly 1 to be measured can be automatically compensated through an algorithm, and the calculation precision of the exceeding width Wi can be improved.

By improving the calculation accuracy exceeding the width Wi, the alignment degree of the second anode pole piece 11 and the second cathode pole piece 12 in the electrode assembly 1 to be measured along the winding axis K can be improved, so that lithium ions are easier to be embedded into an anode active material area of the second anode pole piece 11, the phenomenon of lithium separation is prevented, cathode active materials on the second cathode pole piece 12 fully play a role, the performance of the battery cell 10 is improved, the cycle life and the quick charge capacity of the battery cell 10 are improved, and the safety problems such as combustion, explosion and the like can be reduced.

In addition, the measuring method of the winding electrode assembly can reduce the requirement of the shooting precision of the first shooting part 2 and the second shooting part 3, does not need to select shooting parts with higher precision, does not need to arrange a driving mechanism to enable the first shooting part 2 and the second shooting part 3 to move, saves space, and is convenient to install in a narrow space in a winding machine, thereby reducing cost.

In some embodiments, the first pixel equivalent of the i+1th turn is less than the first pixel equivalent of the i th turn, and the second pixel equivalent of the i+1th turn is greater than the second pixel equivalent of the i th turn.

As shown in fig. 5, the distance between the first photographing part 2 and the second anode electrode sheet 11 is S1, and the distance between the second photographing part 3 and the second cathode electrode sheet 12 is S2.

Along with the increase of the winding thickness of the pole piece, the S1 is gradually reduced, if the first pixel equivalent is kept unchanged, the actual physical size corresponding to a single pixel point in the photographed image is increased, so that the first pixel equivalent needs to be gradually reduced to accurately calculate the actual physical position of the width edge of the second anode pole piece 11. Thus, the first pixel equivalent of the i+1th turn is smaller than the first pixel equivalent of the i-th turn.

Along with the increase of the winding thickness of the pole piece, S2 gradually increases, if the second pixel equivalent is kept unchanged, the actual physical size corresponding to a single pixel point in the photographed image will decrease, so that the second pixel equivalent needs to be gradually increased to accurately calculate the actual physical position of the width edge of the second cathode pole piece 12. Thus, the second pixel equivalent of the i+1th turn is larger than the second pixel equivalent of the i-th turn.

In this embodiment of the present application, by setting the first pixel equivalent of the 1 st to n th turns in the reference electrode assembly 1' to be gradually reduced and the second pixel equivalent to be gradually increased, the variation of the pixel equivalent during the winding of the electrode assembly 1 to be measured can be automatically compensated, thereby improving the calculation accuracy of the excess width Wi and further improving the performance, life and safety of the battery cell 10.

In some embodiments, as shown in fig. 8, the wound electrode assembly measurement method further includes:

s100, calibrating pixel equivalent: calibrating a first pixel equivalent of the ith circle of the reference electrode assembly 1 'according to the image of the first anode electrode piece 11' and the actual size of the first anode electrode piece 11 'in the process of winding the ith circle of the reference electrode assembly 1'; and the second pixel equivalent of the i-th turn of the reference electrode assembly 1' is calibrated according to the image of the first cathode sheet 12' and the actual size of the first cathode sheet 12 '.

Wherein S100 is performed before S110, and before winding a single, multiple or a batch of the same electrode assemblies 1 to be measured, calibration may be performed based on the reference electrode assembly 1' in order to obtain the pixel equivalent parameter corresponding to each turn. During the calibration process, the reference electrode assembly 1' may be wound at the winding station shown in fig. 5, and during the process of winding the ith turn, an image of the first anode electrode sheet 11' may be photographed by the first photographing part 2 and the actual size of the first anode electrode sheet 11' may be measured to calibrate the first pixel equivalent of the ith turn; or the image of the first cathode tab 12 'is photographed by the second photographing part 3 and the actual size of the first cathode tab 12' is measured to mark the second pixel equivalent of the ith turn for use in calculating the excess width Wi of the ith turn in S130.

The embodiment of the application can pre-calibrate the first pixel equivalent and the second pixel equivalent of each circle in the process of winding the reference electrode assembly 1', and can automatically compensate the change of the pixel equivalent in the winding process of the electrode assembly 1 to be measured by adopting the pre-calibrated pixel equivalent parameters when the electrode assembly 1 to be measured is wound, thereby improving the calculation precision of the exceeding width Wi and further improving the performance, service life and safety of the battery cell 10.

In some embodiments, as shown in fig. 9, calibrating the first pixel equivalent of the i-th turn of the reference electrode assembly 1' in S100 based on the image of the first anode electrode sheet 11' and the actual size of the first anode electrode sheet 11' includes:

s101, acquiring an image of a first anode pole piece 11 'of an ith circle, and obtaining a first calibration pixel coordinate of the width edge of the first anode pole piece 11' from the image;

s102, measuring a first actual width of the first anode pole piece 11';

s103, calculating a first pixel equivalent according to the first calibration pixel coordinates and the first actual width.

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

In S101, an image of the first anode electrode sheet 11' photographed by the first photographing part 2 is acquired, and first calibrated pixel coordinates of both side width edges of the first anode electrode sheet 11' are obtained from the image, so that the pixel width dimension of the first anode electrode sheet 11' is obtained from the image.

In S102, the first actual width of the first anode electrode sheet 11 'may be measured by the measuring means 5, and the measuring means 5 may be a precision image type surveying instrument, whereby the physical width dimension of the first anode electrode sheet 11' is measured.

In S103, specifically, the first calibration pixel coordinates of the width edges of the two sides of the first anode pole piece 11 'may be differentiated to obtain the pixel width dimension of the first anode pole piece 11', and the physical width dimension of the first anode pole piece 11 'may be divided by the pixel width dimension of the first anode pole piece 11', so as to calculate the first pixel equivalent.

This embodiment of the present application is capable of obtaining the pixel width dimension of the first anode electrode sheet 11' through an image during the i-th turn of the winding reference electrode assembly 1' and measuring the physical width dimension of the first anode electrode sheet 11', thereby calculating the first pixel equivalent. Because the overall width of the first anode pole piece 11' is relatively large, the measurement of the physical width dimension and the obtaining of the pixel width dimension are more accurate, and the accuracy of the first pixel equivalent calibration can be improved. Alternatively, the first pixel equivalent may also be scaled based on the excess width Wi portion.

In some embodiments, as shown in fig. 10, calibrating the second pixel equivalent of the i-th turn of the reference electrode assembly 1' in S100 based on the image of the first cathode sheet 12' and the actual size of the first cathode sheet 12' includes:

S104, acquiring an image of the ith circle of first cathode pole piece 12', and obtaining a second calibration pixel coordinate of the width edge of the first cathode pole piece 12' from the image;

s105, measuring a second actual width of the first cathode pole piece 12';

s106, calculating a second pixel equivalent according to the second calibration pixel coordinates and the second actual width.

Wherein S106 is performed after S104 and S105, and the order of execution of S104 and S105 is not limited.

In S104, an image of the first cathode sheet 12' photographed by the second photographing part 3 is acquired, and second calibrated pixel coordinates of both side width edges of the first cathode sheet 12' are obtained from the image, so that the pixel width size of the first cathode sheet 12' is obtained from the image.

In S105, the second actual width of the first cathode sheet 12 'may be measured by the measuring part 5, and the measuring part 5 may be a precision image type surveying instrument, thereby measuring the physical width dimension of the first cathode sheet 12'.

In S106, specifically, the second nominal pixel coordinates of the two side edges of the first cathode pole piece 12 'may be differentiated to obtain the pixel width dimension of the first cathode pole piece 12', and the physical width dimension of the first cathode pole piece 12 'may be divided by the pixel width dimension of the first cathode pole piece 12', so as to calculate the second pixel equivalent.

This embodiment of the present application can obtain the pixel width dimension of the first cathode electrode sheet 12' through an image during the i-th turn of the winding reference electrode assembly 1', and measure the physical width dimension of the first cathode electrode sheet 12', thereby calculating the second pixel equivalent. Because the overall width of the first cathode plate 12' is larger, the measurement of the physical width dimension and the obtaining of the pixel width dimension are more accurate, and the accuracy of the second pixel equivalent calibration can be improved.

In some embodiments, as shown in fig. 11, the wound electrode assembly measurement method further includes:

s100', after the step of calibrating the pixel equivalent, the number of turns during the winding of the reference electrode assembly 1' is stored in correspondence with the first pixel equivalent and the second pixel equivalent.

Wherein S100' is performed between S100 and S110. The term "corresponding storage" as used herein refers to storage according to a mapping relationship between the number of turns and the first and second pixel equivalents, i.e. each turn corresponds to one first and one second pixel equivalent. The correspondence relationship may be stored in the storage unit 6, and when the control unit 4 is later acquired, the first pixel equivalent and the second pixel equivalent corresponding to the number of turns may be acquired by a table look-up method only by sending a turn command to the storage unit 6.

In this embodiment, after the pixel equivalent parameter of each circle of the reference electrode assembly 1' is calibrated, the pixel equivalent parameter of each circle is stored in a corresponding relation with the circle, so that the pixel equivalent parameter of each circle is convenient to retrieve when calculating the excess width Wi, so as to efficiently calculate the excess width Wi corresponding to each circle of the electrode assembly 1 to be measured.

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

s131, obtaining a first distance L1i between the width edge of the second anode electrode plate 11 relative to the reference line BL according to the first pixel equivalent of the ith circle of the reference electrode assembly 1' and the first pixel coordinate of the width edge of the second anode electrode plate 11 of the ith circle of the electrode assembly 1 to be detected;

s132, obtaining a second distance L2i between the width edge of the second cathode pole piece 12 relative to the datum line BL according to the second pixel equivalent of the ith circle of the reference electrode assembly 1' and the second pixel coordinate of the width edge of the second cathode pole piece 12 of the ith circle of the electrode assembly 1 to be detected;

s133, calculating the exceeding width Wi of the ith circle of second anode pole piece 11 relative to the second cathode pole piece 12 according to the difference value of the first distance L1i and the second distance L2 i.

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

In S131, a reference line BL may be first selected, and a pixel distance between the width edge of the second anode electrode sheet 11 and the reference line BL in the image may be obtained according to the first pixel coordinate of the width edge of the second anode electrode sheet 11 and the position of the reference line BL; next, the pixel distance of the i-th turn is multiplied by the first pixel coordinate to obtain a first distance L1i between the width edge of the second anode tab 11 and the reference line BL, where the first distance L1i is the actual physical dimension.

In S132, the same reference line BL is adopted, and a pixel distance between the width edge of the second cathode sheet 12 and the reference line BL in the image is obtained according to the second pixel coordinate of the width edge of the second cathode sheet 12 and the position of the reference line BL; next, the pixel distance of the i-th turn is multiplied by the second pixel coordinate to obtain a second distance L2i between the width edge of the second cathode tab 12 and the reference line BL, where the second distance L2i is the actual physical dimension.

In S133, according to the difference between the first distance L1i and the second distance L2i, the excess width Wi of the ith turn of the second anode electrode sheet 11 relative to the second cathode electrode sheet 12 is calculated, and when calculating the excess width Wi of a certain side, the pixel coordinates of the corresponding side width edges of the second anode electrode sheet 11 and the second cathode electrode sheet 12 can be used for calculation.

The embodiment of the application can obtain the exceeding width Wi of the second anode pole piece 11 of the ith circle relative to the second cathode pole piece 12 based on the corresponding pixel equivalent parameter of each i circle in the reference electrode assembly 1', and can accurately and conveniently calculate the exceeding width Wi so as to improve the performance, service life and safety of the battery cell 10.

In some embodiments, S133 calculating 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 includes:

acquiring a deviation adjusting value in advance;

the difference and the deviation adjustment value are summed to calculate the excess width Wi of the second anode electrode sheet 11 relative to the second cathode electrode sheet 12.

Wherein the deviation adjustment value can be set according to the deviation of the actual physical positions of the first photographing part 2 and the second photographing part 3 in the direction of the winding axis K to compensate for the inherent error brought by the detection device, so that the central lines of the images photographed by the first photographing part 2 and the second photographing part 3 respectively coincide to uniformly calculate the reference when the first pixel coordinates and the second pixel coordinates.

This embodiment of the present application allows the center lines of the respective photographed images of the first photographing part 2 and the second photographing part 3 to coincide by introducing the deviation adjustment value in consideration of the deviation of the actual physical positions of the first photographing part 2 and the second photographing part 3 set in the winding axis K direction, so that the references for obtaining the first pixel coordinates and the second pixel coordinates are unified, and the accuracy of the calculation result is improved.

In some embodiments, the reference line BL is a center line of the second anode tab 11 of the electrode assembly 1 to be measured between both side width edges, or a center line of the second cathode tab 12 between both side width edges. Because the distances between the center line of the pole piece and the width edges at the two sides of the pole piece are consistent, the larger error of the calculation result of the width Wi exceeding the two sides due to the too close or too far position of the datum line BL is prevented, and the calculation result of the width Wi exceeding the two sides of the electrode assembly 1 to be measured can be more accurate. Alternatively, the reference line BL may be selected at other positions.

In some embodiments, in the process of winding the electrode assembly 1 to be measured, the step of acquiring the pixel coordinates is sequentially performed from the 1 st turn to the n th turn, and after all the steps of acquiring the pixel coordinates are performed, the step of calculating the excess width is performed for each turn of the electrode assembly 1 to be measured, so as to obtain W1, W2, …, wi, wn. The wound electrode assembly measurement method further includes:

judging whether the difference between the maximum exceeding width and the minimum exceeding width in the W1, W2, …, wi, wn of the electrode assembly 1 to be measured exceeds a preset deviation, if not, judging that the electrode assembly 1 to be measured is qualified in winding, and if so, judging that the electrode assembly 1 to be measured is unqualified in winding.

Wherein, in the process of winding each turn of the electrode assembly 1 to be measured, the step of acquiring pixel coordinates is sequentially performed to obtain a first pixel coordinate of the width edge of the second anode electrode sheet 11 and a second pixel coordinate of the width edge of the second cathode electrode sheet 12 from the images shot by the first shooting part 2 and the second shooting part 3. After the electrode assembly 1 to be measured is wound, the excess width Wi of each turn is calculated, and whether the electrode assembly 1 to be measured is wound is qualified is determined through S140. The preset deviation is set according to the process requirements of the electrode assembly 1 to be measured, for example, the performances of the battery cells 10 under different preset deviations are tested through experiments to obtain acceptable preset deviations.

After the electrode assembly 1 to be measured is wound, the excess width Wi of each circle is calculated respectively, so that whether the electrode assembly 1 to be measured is wound is qualified or not is judged, and the excess widths Wi corresponding to all circles can be compared by the method to obtain the maximum deviation, so that the winding is judged to be qualified as long as the maximum deviation does not exceed the preset deviation. Moreover, the method can further enable the whole winding process of the electrode assembly 1 to be measured to be more continuous, keep the tension of the pole piece uniform in the winding process, and improve the winding efficiency.

Optionally, the step of acquiring the pixel coordinates is performed during the winding of the electrode assembly 1 to be measured for the ith turn, and the step of calculating the excess width is performed before the winding for the (i+1) th turn, which is advantageous in judging whether the excess width Wi of the turn satisfies the requirement after each winding, so as to more strictly satisfy the dimensional requirement, and taking corrective adjustment measures in case the requirement is not satisfied.

Some specific examples will be given below, referring to fig. 7 to 11, the measuring method of the rolled electrode assembly of the present application is as follows:

1. winding of one reference electrode assembly 1' is started in the winder, and the step of calibrating pixel equivalent is performed by the control part 4 during each winding, S100 including the following steps (1) to (3).

(1) In the process of winding the ith circle, the first shooting part 2 and the second shooting part 3 respectively shoot images of the first anode pole piece 11 'and the first cathode pole piece 12', and respectively obtain a first calibration pixel coordinate of the width edge of the first anode pole piece 11 'and a second calibration pixel coordinate of the first cathode pole piece 12' from the two images.

(2) The first actual width of the first anode electrode sheet 11 'and the second actual width of the first cathode electrode sheet 12' are measured, respectively.

(3) Calculating a first pixel equivalent according to the first calibrated pixel coordinates and the first actual width; and calculating a second pixel equivalent according to the second calibrated pixel coordinates and the second actual width.

2. After the step of calibrating the pixel equivalent, the number of turns during the winding of the reference electrode assembly 1 'is stored corresponding to the first pixel equivalent and the second pixel equivalent, S100' is performed.

3. Starting winding one electrode assembly 1 to be measured in a winding machine, and performing S120 a step of acquiring pixel coordinates during each winding, S120 including:

in the process of winding the ith circle of the electrode assembly 1 to be measured, an image of the second anode electrode plate 11 of the electrode assembly 1 to be measured is shot, a first pixel coordinate of the width edge of the second anode electrode plate 11 is obtained from the image, an image of the second cathode electrode plate 12 of the electrode assembly 1 to be measured is shot, and a second pixel coordinate of the width edge of the second cathode electrode plate 12 is obtained from the image.

4. After the electrode assembly 1 to be measured is wound, the excess width Wi of each circle is calculated respectively, and the specific calculation method is as follows:

the step of acquiring pixel equivalent S110 and the step of calculating the excess width S130 are sequentially performed by the control section 4 for each turn to read the pixel equivalent parameter of the layer from the storage section 6 and to calculate the excess width Wi.

5. Judging whether the difference between the maximum exceeding width and the minimum exceeding width in the W1, W2, …, wi, wn of the electrode assembly 1 to be measured exceeds a preset deviation, if not, judging that the electrode assembly 1 to be measured is qualified in winding, and if so, judging that the electrode assembly 1 to be measured is unqualified in winding.

Next, the present disclosure provides a wound electrode assembly measuring apparatus, and in the following embodiments, since some terms have been explained in detail in the subject of the wound electrode assembly measuring method, a detailed description thereof will be omitted.

In some embodiments, as shown in fig. 5 and 12, the wound electrode assembly measuring apparatus includes:

a first photographing part 2 configured to photograph an image of a first anode tab 11 'of the reference electrode assembly 1', or an image of a second anode tab 11 of the electrode assembly 1 to be measured;

a second photographing part 3 configured to photograph an image of the first cathode tab 12 'of the reference electrode assembly 1', or an image of the second cathode tab 12 of the electrode assembly 1 to be measured; and

a control part 4 configured to acquire pixel equivalent parameters corresponding to the i-th turn of the winding reference electrode assembly 1', the pixel equivalent parameters including: referring to the first pixel equivalent of the first anode electrode tab 11' and the second pixel equivalent of the first cathode electrode tab 12' of the electrode assembly 1 '; in the process of winding the ith circle of the electrode assembly 1 to be measured, acquiring an image of the second anode electrode plate 11 of the electrode assembly 1 to be measured, acquiring a first pixel coordinate of the width edge of the second anode electrode plate 11 from the image, acquiring an image of the second cathode electrode plate 12 of the electrode assembly 1 to be measured, and acquiring a second pixel coordinate of the width edge of the second cathode electrode plate 12 from the image; and calculating the exceeding width Wi of the second anode pole piece 11 in the ith circle of the electrode assembly 1 to be measured along the winding axis K relative to the second cathode pole piece 12 according to the first pixel equivalent and the second pixel equivalent of the ith circle of the reference electrode assembly 1' and the first pixel coordinate and the second pixel coordinate of the ith circle of the electrode assembly 1 to be measured.

The first photographing part 2 and the second photographing part 3 may be various cameras, taking the electrode assembly 1 to be measured as an example, the first photographing part 2 may photograph the second anode electrode piece 11 wound on the winding shaft K through the second diaphragm 13 by using an infrared camera, and the distance between the first photographing part 2 and the second anode electrode piece 11 is S1; the second photographing part 3 may photograph the second cathode sheet 12 to be wound on the winding shaft K, and a distance between the second photographing part 3 and the second cathode sheet 12 is S2. S1 and S2 can be selected according to actual requirements.

According to the embodiment of the 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', so that the exceeding width Wi of the circle can be calculated by adopting the corresponding first pixel equivalent and second pixel equivalent in the process of winding the electrode assembly 1 to be tested for different circles, the change of the pixel equivalent in the winding process of the electrode assembly 1 to be tested can be automatically compensated through an algorithm, the calculation precision of the exceeding width Wi can be improved, and the performance, the service life and the safety of the battery cell 10 are improved.

In addition, the measuring method of the winding electrode assembly can reduce the requirement of the shooting precision of the first shooting part 2 and the second shooting part 3, does not need to select a shooting part with higher precision or shoot with a micro distance, does not need to arrange a driving mechanism to enable the first shooting part 2 and the second shooting part 3 to move, saves space, and is convenient to install in a narrow space in a winding machine, thereby reducing cost.

In some embodiments, as shown in fig. 5, the first photographing part 2 and the second photographing part 3 are fixedly provided at the same side of the winding axis K of the reference electrode assembly 1' or the electrode assembly 1 to be measured.

Wherein the first photographing part 2 and the second photographing part 3 may be disposed at different positions of the winding axis K in the circumferential direction in a plane perpendicular to the winding axis K such that the first photographing part 2 and the second photographing part 3 have different angle photographing to obtain an optimal photographing angle. The first photographing part 2 and the second photographing part 3 may be located at the same position in the extending direction of the winding shaft K, or may be disposed to be offset. In order to ensure the shooting effect, a light supplementing lamp can be arranged.

This embodiment of the present application provides the first photographing part 2 and the second photographing part 3 on the same side of the winding axis K, which can save space occupied in the winding machine, facilitate installation, and facilitate selection of the reference line BL based on the installation position of the photographing parts. In addition, the first shooting part 2 and the second shooting part 3 are fixedly arranged, a driving mechanism is not required to be arranged to enable the first shooting part 2 and the second shooting part 3 to move, space can be further saved, installation in a narrow space in a winding machine is facilitated, and therefore cost can be reduced.

In some embodiments, as shown in fig. 14, the control part 4 includes: a calibration unit 41 configured to calibrate a first pixel equivalent of an i-th turn of the reference electrode assembly 1 'according to an image of the first anode electrode sheet 11' and an actual size of the first anode electrode sheet 11 'during the winding of the i-th turn of the reference electrode assembly 1'; and the second pixel equivalent of the i-th turn of the reference electrode assembly 1' is calibrated according to the image of the first cathode sheet 12' and the actual size of the first cathode sheet 12 '.

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

The calibration unit 41 is configured to acquire an image of the ith circle of first anode pole piece 11', obtain a first calibration pixel coordinate of the width edge of the first anode pole piece 11' from the image, and calculate a first pixel equivalent according to the first calibration pixel coordinate and the first actual width; and acquiring an image of the ith circle of the first cathode pole piece 12', obtaining second calibration pixel coordinates of the width edge of the first cathode pole piece 12' from the image, and calculating second pixel equivalent according to the second calibration pixel coordinates and the second actual width.

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

This embodiment of the present application is capable of obtaining the pixel width dimensions of the first anode electrode tab 11' and the first cathode electrode tab 12' by image and measuring the physical width dimensions of the first anode electrode tab 11' and the first cathode electrode tab 12' during the i-th turn of the winding reference electrode assembly 1', thereby calculating the first pixel equivalent and the second pixel equivalent. Because the overall width of the first anode electrode piece 11 'and the first cathode electrode piece 12' is relatively larger, the measurement of the physical width dimension and the obtaining 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.

In some embodiments, as shown in fig. 14, the wound electrode assembly measuring apparatus further includes: and a storage part 6 configured to store the number of turns of the calibrated reference electrode assembly 1' during winding in correspondence with the first pixel equivalent and the second pixel equivalent.

The term "corresponding storage" as used herein refers to storage according to a mapping relationship between the number of turns and the first and second pixel equivalents, i.e. each turn corresponds to one first and one second pixel equivalent. The correspondence relationship may be stored in the storage unit 6, and when the storage unit 6 is subsequently acquired, the control unit 4 may acquire the first pixel equivalent and the second pixel equivalent corresponding to the number of turns by using a table look-up method only by sending a turn command to the storage unit 6. For example, the storage section 6 may be a magnetic disk, a flash memory, or any other nonvolatile storage medium.

In some embodiments, as shown in fig. 14, the control part 4 includes: an alignment degree calculating unit 42 configured to obtain a first distance L1i between the width edge of the second anode electrode sheet 11 with respect to the reference line BL according to a first pixel equivalent of the i-th turn of the reference electrode assembly 1' and a first pixel coordinate of the width edge of the second anode electrode sheet 11 of the i-th turn of the electrode assembly 1 to be measured during the winding of the i-th turn of the electrode assembly 1; obtaining a second distance L2i between the width edge of the second cathode pole piece 12 relative to the reference line BL according to a second pixel equivalent of the width edge of the second cathode pole piece 12 of the ith circle of the reference electrode assembly 1' and a second pixel coordinate of the ith circle of the electrode assembly 1 to be detected; and then, calculating the exceeding width Wi of the second anode pole piece 11 relative to the second cathode pole piece 12 according to the difference value of the first distance L1i and the second distance L2 i.

In some embodiments, the alignment calculation unit 42 is configured to sum the difference value with a previously 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.

Wherein the deviation adjustment value can be set according to the deviation of the actual physical positions of the first photographing part 2 and the second photographing part 3 in the direction of the winding axis K to compensate the inherent error brought by the detection device, so that the central lines of the images photographed by the first photographing part 2 and the second photographing part 3 are overlapped to uniformly calculate the reference when the first pixel coordinate and the second pixel coordinate.

The control unit 4, calibration unit 41 and alignment calculation unit 42 in the above embodiments may be general purpose processors, programmable logic controllers (Programmable Logic Controller, abbreviated as PLCs), digital signal processors (Digital Signal Processor, abbreviated as DSPs), application specific integrated circuits (Application Specific Integrated Circuit, abbreviated as ASICs), field-programmable gate arrays (fields-Programmable Gate Array, abbreviated as FPGAs) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or any suitable combination thereof for performing the functions described in the present disclosure.

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, the technical features mentioned in the respective embodiments may be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions falling within the scope of the claims.

Claims

A wound electrode assembly measurement method, comprising:

a step of acquiring pixel equivalent: acquiring pixel equivalent parameters corresponding to the ith turn of the coiled reference electrode assembly (1'), wherein the pixel equivalent parameters comprise: 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 '), wherein i is more than or equal to 1 and less than or equal to n, i is a natural number, and n is a total number of turns;

acquiring pixel coordinates: in the process of winding an ith circle of an electrode assembly (1) to be measured, shooting an image of a second anode pole piece (11) of the electrode assembly (1) to be measured, obtaining a first pixel coordinate of the width edge of the second anode pole piece (11) from the image, shooting an image of a second cathode pole piece (12) of the electrode assembly (1) to be measured, and obtaining a second pixel coordinate of the width edge of the second cathode pole piece (12) from the image;

Calculating the excess width: according to the first pixel equivalent and the second pixel equivalent corresponding to the ith circle of the reference electrode assembly (1'), and the first pixel coordinate and the second pixel coordinate of the ith circle of the electrode assembly (1) to be detected, calculating the exceeding width Wi of the second anode pole piece (11) relative to the second cathode pole piece (12) along the winding axis (K) in the ith circle of the electrode assembly (1) to be detected.
The wound electrode assembly measurement method according to claim 1, further comprising:

calibrating pixel equivalent: -during winding of the ith turn of the reference electrode assembly (1 '), calibrating a first pixel equivalent of the ith turn of the reference electrode assembly (1') according to the image of the first anode electrode sheet (11 ') and the actual dimensions of the first anode electrode sheet (11'); and a second pixel equivalent of the ith turn of the reference electrode assembly (1 ') is defined based on the image of the first cathode sheet (12 ') and the actual size of the first cathode sheet (12 ').
The coiled electrode assembly measurement method according to claim 2, wherein the scaling of the first pixel equivalent of the i-th turn 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 ') comprises:

Acquiring an image of the first anode pole piece (11 ') of the ith circle, and obtaining a first calibration pixel coordinate of the width edge of the first anode pole piece (11') from the image;

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

and calculating the first pixel equivalent according to the first calibration pixel coordinates and the first actual width.
A coiled electrode assembly measurement method according to claim 2 or 3, wherein the mapping of the second pixel equivalent of the i-th turn of the reference electrode assembly (1 ') based on the image of the first cathode sheet (12 ') and the actual size of the first cathode sheet (12 ') comprises:

acquiring an image of the first cathode pole piece (12 ') of the ith circle, and obtaining a second calibration pixel coordinate of the width edge of the first cathode pole piece (12') from the image;

measuring a second actual width of the first cathode sheet (12');

and calculating the second pixel equivalent according to the second calibration pixel coordinates and the second actual width.
The wound electrode assembly measurement method according to any one of claims 2 to 4, further comprising:

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

according to the first pixel equivalent of the ith circle of the reference electrode assembly (1') and the first pixel coordinate of the width edge of the second anode pole piece (11) of the ith circle of the electrode assembly (1) to be detected, a first distance L1i between the width edge of the second anode pole piece (11) relative to a datum line (BL) is obtained;

obtaining a second distance L2i between the width edge of the second cathode pole piece (12) relative to the datum line (BL) according to the second pixel equivalent of the ith circle of the reference electrode assembly (1') and a second pixel coordinate of the width edge of the second cathode pole piece (12) of the ith circle of the electrode assembly (1) to be detected;

and calculating the exceeding width Wi of the second anode pole piece (11) relative to the second cathode pole piece (12) of the ith circle according to the difference value of the first distance L1i and the second distance L2 i.
The wound electrode assembly measurement method according to claim 6, wherein calculating the excess width Wi of the second anode sheet (11) relative to the second cathode sheet (12) from the difference of the first distance L1i and the second distance L2i comprises:

Acquiring a deviation adjusting value in advance;

and summing the difference value and the deviation adjustment value, and calculating the exceeding 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 an image of the first anode electrode sheet (11 ') or the second anode electrode sheet (11), and the second photographing part (3) is configured to photograph an image of the first cathode electrode sheet (12') or an image of the second cathode electrode sheet (12).
The rolled electrode assembly measurement method according to any one of claims 1 to 7, wherein the step of acquiring pixel coordinates is performed sequentially from 1 st turn to nth turn during the rolling of the electrode assembly (1) to be measured, and after all the steps of acquiring pixel coordinates are performed, the step of calculating the excess width is performed for each turn of the electrode assembly (1) to be measured to obtain W1, W2, …, wi, wn;

the wound electrode assembly measurement method further includes:

and judging that the electrode assembly (1) to be measured is wound to be qualified under the condition that the difference between the maximum exceeding width and the minimum exceeding width in W1, W2 and …, wi and Wn of the electrode assembly (1) to be measured does not exceed a preset deviation.
A wound electrode assembly measurement device, comprising:

a first photographing part (2) configured to photograph an image of a first anode tab (11 ') of a reference electrode assembly (1'), or an image of a second anode tab (11) of an electrode assembly (1) to be measured;

a second photographing part (3) configured to photograph an image of a first cathode tab (12 ') of the reference electrode assembly (1'), or an image of a second cathode tab (12) of the electrode assembly (1) to be measured; and

a control part (4) configured to acquire a pixel equivalent parameter corresponding to an i-th turn of the wrap-around reference electrode assembly (1'), the pixel equivalent parameter including: a first pixel equivalent of a first anode electrode sheet (11 ') and a second pixel equivalent of a first cathode electrode sheet (12 ') of the reference electrode assembly (1 '); in the process of winding the ith circle of the electrode assembly (1) to be measured, acquiring an image of a second anode pole piece (11) of the electrode assembly (1) to be measured, acquiring a first pixel coordinate of the width edge of the second anode pole piece (11) from the image, acquiring an image of a second cathode pole piece (12) of the electrode assembly (1) to be measured, and acquiring a second pixel coordinate of the width edge of the second cathode pole piece (12) from the image; and calculating the exceeding width Wi of the second anode pole piece (11) relative to the second cathode pole piece (12) along the winding axis (K) in the ith circle of the electrode assembly (1) to be detected according to the first pixel equivalent and the second pixel equivalent of the ith circle of the reference electrode assembly (1') and the first pixel coordinate and the second pixel coordinate of the ith circle of the electrode assembly (1) to be detected.
The coiled electrode assembly measuring device according to claim 9, wherein the first photographing part (2) and the second photographing part (3) are fixedly provided on the same side of the reference electrode assembly (1') or the coiling axis (K) of the electrode assembly (1) to be measured.
The rolled electrode assembly measuring device according to claim 9 or 10, wherein the control member (4) comprises:

a calibration unit (41) configured to calibrate a first pixel equivalent of an i-th turn of the reference electrode assembly (1 ') according to an image of the first anode electrode sheet (11') and an actual size of the first anode electrode sheet (11 ') during a winding of the i-th turn of the reference electrode assembly (1'); and a second pixel equivalent of the ith turn of the reference electrode assembly (1 ') is defined based on the image of the first cathode sheet (12 ') and the actual size of the first cathode sheet (12 ').
The wound electrode assembly measurement device of claim 11, further comprising:

a measuring member (5) configured to measure a first actual width of the first anode electrode sheet (11 ') and a second actual width of the first cathode electrode sheet (12 ') in the reference electrode assembly (1 ');

wherein the calibration unit (41) is configured to acquire an image of the first anode pole piece (11 ') of the ith circle, obtain a first calibration pixel coordinate of the width edge of the first anode pole piece (11') from the image, and calculate the first pixel equivalent according to the first calibration pixel coordinate and the first actual width; and acquiring an image of the first cathode pole piece (12 ') of the ith circle, obtaining second calibration pixel coordinates of the width edge of the first cathode pole piece (12') from the image, and calculating the second pixel equivalent according to the second calibration pixel coordinates and the second actual width.
The wound electrode assembly measurement device according to claim 11 or 12, further comprising:

and a storage unit (6) configured to store the number of turns of the calibrated reference electrode assembly (1') during winding in correspondence with the first pixel equivalent and the second pixel equivalent.
The wound electrode assembly measurement device according to any one of claims 9 to 13, wherein the control member (4) includes:

an alignment degree calculating unit (42) configured to derive a first distance L1i between a width edge of the second anode electrode sheet (11) with respect to a reference line (BL) from the first pixel equivalent of the i-th turn of the reference electrode assembly (1') and a first pixel coordinate of the width edge of the second anode electrode sheet (11) of the i-th turn of the electrode assembly (1) to be measured in a process of winding the i-th turn of the electrode assembly (1); obtaining a second distance L2i between the width edge of the second cathode pole piece (12) relative to the datum line (BL) according to the second pixel equivalent of the ith circle of the reference electrode assembly (1') and a second pixel coordinate of the width edge of the second cathode pole piece (12) of the ith circle of the electrode assembly (1) to be detected; and then, calculating the exceeding width Wi of the second anode pole piece (11) relative to the second cathode pole piece (12) according to the difference value of the first distance L1i and the second distance L2 i.
The wound electrode assembly measurement device according to claim 14, wherein the alignment calculation unit (42) is configured to calculate an excess width Wi of the second anode sheet (11) relative to the second cathode sheet (12) by summing the difference value with a previously acquired deviation adjustment value.