Battery cell tab defect detection method and tab defect detection device

Abstract

A battery cell tab defect detection method and a tab defect detection device, relating to the field of batteries. The tab defect detection method comprises: obtaining a first image of a first side of a tab stack of the battery cell, and a second image of a second side opposite the first side, the first and second sides being two faces parallel to a stacking direction of the tab stack and extending along a height direction of the tab; obtaining a first detection result based on the first image, and a second detection result based on the second image, the first and second detection results indicating: whether a tab in the tab stack has a first type defect, and a position of the first type defect, the first type defect comprising a tab line abnormality, and the position of the first type defect indicating the relative position of the first type defect on the height of the tab; and, based on the first and the second detection result, determining whether or not the tab stack has a defect in a fold to a membrane region. Said method can more accurately detect a tab folding defect, so as to determine whether or not a battery cell meets requirements.

Description

Battery cell tab defect detection method and tab defect detection equipment

[0001] Cross-references to related publications

[0002] The embodiments of the present disclosure are based on and claim the priority of Chinese patent application with application number 202410030247.1, application date January 9, 2024, and application name “Tap Defect Detection Method and Tab Defect Detection Device”. The entire content of the Chinese patent application is hereby introduced into the present disclosure as a reference. Technical Field

[0003] The present disclosure relates to the field of batteries, and in particular to a method and device for detecting tab defects in battery cells. Background Art

[0004] Lithium-ion battery cell production processes primarily involve winding and lamination. In both winding and lamination processes, the thinness and low strength of the cathode and anode tabs (e.g., made of aluminum or copper foil) can easily lead to defects such as folding and wrinkling during cell production. Therefore, it is necessary to detect tab folding defects to determine cell quality.

[0005] Summary of the Invention

[0006] In view of the above problems, the present disclosure provides a tab defect detection method and a tab defect detection device for a battery cell, which can more accurately detect tab folding defects to determine whether the battery cell is qualified.

[0007] In a first aspect, the present disclosure provides a method for detecting tab defects in a battery cell, comprising: obtaining a first image of a first side of a tab stack of the battery cell and a second image of a second side of the tab stack opposite to the first side, wherein the first side and the second side are two surfaces parallel to the stacking direction of the tab stack and extending along the height direction of the tabs in the tab stack; obtaining a first detection result of tab defect detection based on the first image and a second detection result of tab defect detection based on the second image, wherein the first detection result and the second detection result indicate: whether a first type of defect exists in the tab in the tab stack; and the position of the first type of defect, the first type of defect including tab line abnormality, the position of the first type of defect indicating the relative position of the first type of defect at the height of the tab; and determining whether the tab stack has a fold-over to membrane area defect based on the first detection result and the second detection result.

[0008] In the first aspect mentioned above, since the defect detection results and defect positions of the first image and the second image of the two sides of the tab stack are comprehensively considered to determine whether the tab stack has a fold-over to the membrane area defect, it is possible to avoid judging a slight fold or wrinkle defect of a certain layer of tab as a serious defect (i.e., a fold-over to the membrane area defect), thereby significantly improving the yield of the battery cell and reducing the workload of manual secondary re-judgment.

[0009] In a second aspect, a tab defect detection device for a battery cell is provided, comprising: a first camera, located at a position opposite to a first side surface of a tab stack of the battery cell, for capturing a first image of the first side surface; a second camera, located at a position opposite to a second side surface of the tab stack, for capturing a second image of the second side surface, wherein the first side surface and the second side surface are two surfaces parallel to a stacking direction of the tab stack and extending along a height direction of the tab in the tab stack; a controller, communicatively connected to the first camera and the second camera, for obtaining the first image and the second image, and transmitting the first image and the second image to a processing unit. a processor, communicatively connected to the controller, for performing tab defect detection based on the first image to obtain a first detection result; and performing tab defect detection based on the second image to obtain a second detection result, wherein the first detection result and the second detection result indicate: whether the tab in the tab stack has a first type of defect; and the position of the first type of defect, wherein the first type of defect includes an abnormal tab line, and the position of the first type of defect indicates the relative position of the first type of defect at the height of the tab; the controller is also used to determine whether the tab stack has a fold-over to membrane area defect based on the first detection result and the second detection result.

[0010] The above description is only an overview of the technical solution of the present disclosure. In order to more clearly understand the technical means of the present disclosure, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present disclosure more obvious and easy to understand, the specific implementation methods of the present disclosure are listed below.

[0011] It should be understood that the above general description and the following detailed description are merely exemplary and explanatory, and are not intended to limit the technical solutions of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present disclosure. The same reference numerals are used throughout the drawings to denote the same components. In the drawings:

[0013] FIG1 is a schematic top view of a battery cell according to one embodiment of the present disclosure.

[0014] FIG2 is a schematic flowchart of a method for detecting tab defects in a battery cell according to an embodiment of the present disclosure.

[0015] FIG. 3 is a schematic diagram for explaining an example of a defect position determination criterion according to an embodiment of the present disclosure.

[0016] FIG. 4 is a schematic diagram for explaining an example of a defect position determination criterion according to an embodiment of the present disclosure.

[0017] FIG. 5 is a schematic diagram for explaining an example of a defect position determination criterion according to an embodiment of the present disclosure.

[0018] FIG. 6 is a schematic diagram for explaining an example of a defect position determination criterion according to an embodiment of the present disclosure.

[0019] FIG7 is a schematic flowchart of a method for detecting tab defects in a battery cell according to another embodiment of the present disclosure.

[0020] FIG8 is a schematic flow chart for illustrating a method for determining whether a tab is folded into a film region according to an embodiment of the present disclosure.

[0021] FIG. 9 is a schematic diagram showing the structure of a tab defect detection device according to an embodiment of the present disclosure.

[0022] The reference numerals in the specific embodiment are as follows: battery cell 1; battery cell body 10, first tab stack 11, second tab stack 12, diaphragm 13, first side 111, second side 112; tab defect detection device 300; first camera 301, second camera 303, controller 303, processor 304. DETAILED DESCRIPTION

[0023] The following embodiments of the technical solution of the present disclosure are described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present disclosure and are therefore only examples and are not intended to limit the scope of protection of the present disclosure.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present disclosure belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure; the terms "including" and "having" and any variations thereof in the specification and claims of the present disclosure and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0025] In the description of the embodiments of the present disclosure, technical terms such as "first" and "second" are used solely to distinguish between different objects and should not be understood to indicate or imply relative importance or to implicitly specify the quantity, specific order, or primary and secondary relationship of the technical features indicated. In the description of the embodiments of the present disclosure, "plurality" means more than two, unless otherwise specifically defined.

[0026] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present disclosure. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0027] In the description of the embodiments of the present disclosure, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0028] In the description of the embodiments of the present disclosure, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0029] In the description of the embodiments of the present disclosure, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the embodiments of the present disclosure.

[0030] In the description of the embodiments of the present disclosure, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and they can refer to internal connectivity between two components or interaction between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present disclosure based on specific circumstances.

[0031] The manufacturing methods for bare battery cells primarily include winding and lamination. The battery cell tabs are typically die-cut to retain only the portion of the metal foil needed to pass current. This portion of the foil is known as the tab. Because the metal foil used for the tabs is extremely thin and inherently weak, the tabs are prone to defects such as folding, wrinkling, and inward shrinkage during the production process.

[0032] For example, during the winding process, multiple layers of tabs overlap after winding (hereinafter referred to as tab stacking), making it difficult to detect the degree to which each layer of tabs is folded inward or longitudinally through imaging. Since the tab metal foil (e.g., copper foil, aluminum foil) is thin and light, even a small external force collision during material handling can cause tab deformation on the entire batch of materials. In addition, during the winding process, the tabs move at high speed during feeding and passing the rollers, and the distance between the tabs and the winding plate is small. Therefore, the tabs are also prone to interference damage, resulting in folding of the tab tails.

[0033] In previous methods for detecting defects in the tabs of bare cells, the left and right sides of the tab stack are photographed using, for example, a 2D camera or a charge-coupled device (CCD) camera. The tab stack image on one of the left and right sides is then inspected using an algorithm such as an artificial intelligence (AI) algorithm. When the similarity between the detected feature and the feature in the defect library reaches a set threshold, the judgment result is output.

[0034] However, previous tab defect detection methods only consider images of a single tab stack, failing to determine the extent of the detected defects' impact on battery cell safety and quality. In actual production, due to the unique characteristics of tab materials, even minor folds or wrinkles in the tab stack can be detected by the algorithm, resulting in a decrease in yield. In some cases, this yield reduction necessitates a manual re-inspection, increasing the workload.

[0035] In light of the above, the present disclosure was developed. This disclosure comprehensively considers images of the left and right sides of the tab stack to determine whether a tab in the tab stack is likely to fold over into the diaphragm area. Only if this is likely, the battery cell is deemed unqualified. This significantly improves product yield and reduces the workload of manual secondary re-evaluation.

[0036] A battery cell is the component where electrochemical reactions occur. A battery cell is primarily composed of a positive electrode sheet and a negative electrode sheet wound or stacked, typically with a separator between them. The portions of the positive and negative electrode sheets containing active material form the main body of the battery cell, while the portions of the positive and negative electrode sheets without active material each form a tab. The positive and negative tabs can be located together at one end of the main body or separately at opposite ends. During the battery's charge and discharge process, the positive and negative active materials react with the electrolyte, and the tabs connect to the battery's electrode terminals to form a current circuit.

[0037] FIG1 is a schematic top view of a battery cell 1. The battery cell 1 includes a cell body 10, a first tab stack 11, and a second tab stack 12. For example, the first tab stack 11 and the second tab stack 12 may correspond to a cathode tab stack and an anode tab stack, respectively. In FIG1 , the first tab stack 11 and the second tab stack 12 are stacked in a direction perpendicular to the paper, but this stacking is not shown in the figure. The first tab stack 11 has a first side surface 111 (the right side surface in the figure) and a second side surface 112 (the left side surface in the figure). The second tab stack 12 also has a first side surface and a second side surface (not marked with reference numerals in the figure).

[0038] The first tab stack 11 and the second tab stack 12 may be in a substantially trapezoidal shape, however, the present disclosure is not limited thereto, and the first tab stack 11 and the second tab stack 12 may be in any shape such as a rectangle.

[0039] As shown in FIG1 , the first tab stack 11 and the second tab stack 12 have a tab height H, which represents the height from the surface of the battery cell 1 to the tab end (top end). In addition, the first tab stack 11 and the second tab stack 12 have a tab width W, which represents the length of the tab end between the first side 111 and the second side 112.

[0040] In Figure 1, the outermost layer of the surface of the battery cell 1 is covered with a diaphragm 13, which is used to protect the battery cell 1 and isolate and insulate the battery cell 1 from the outside world. In the present disclosure, the area where the diaphragm 13 is located may also be referred to as a membrane area, a diaphragm area, or a diaphragm area. If a tab in the tab stack is folded onto the membrane area, even if the tab has not yet scratched the diaphragm but only touched the diaphragm, the present disclosure will also regard this situation as a tab stack or tab folding onto the membrane area defect. This is because during the subsequent battery production or use process, the tab may eventually scratch the diaphragm, thereby posing a risk of battery short circuit.

[0041] On the contrary, if there is no defect of folding to the membrane area, then even if a tab in the tab stack has a defect such as folding, wrinkling, or shrinking, since such a minor defect will not have a substantial impact on the subsequent production and use of the battery, the present disclosure considers the battery cell 1 in this case to be qualified. Shrinking refers to the situation in which a tab of a layer is not visible in the image of the tab stack due to the indentation of the tab.

[0042] Therefore, according to the present disclosure, first, a defect detection algorithm such as an AI detection algorithm is used to determine whether visual defects such as folding and wrinkling exist for a first image of the first side 111 and a second image of the second side 112 of the tab stack 11 or 12. Then, the determination results for the first side 111 and the second side 112 are combined to determine whether a tab fold-to-film region defect exists in the tab stack.

[0043] The following describes a tab defect detection method according to an embodiment of the present disclosure in conjunction with Figures 1 and 2. Figure 2 is a flow chart of a tab defect detection method for a battery cell according to an embodiment of the present disclosure.

[0044] As shown in FIG2 , the tab defect detection method includes steps 201, 202, and 203. 201: obtaining a first image of a first side surface 111 of a tab stack of a battery cell and a second image of a second side surface 112 of the tab stack opposite to the first side surface, wherein the first side surface and the second side surface are two surfaces of the tab stack that are parallel to the stacking direction of the tab stack (the direction perpendicular to the paper in FIG1 ) and extend along the height direction of the tab in the tab stack (the up and down extension direction of the arrow of the height H as shown in FIG1 ); 202: obtaining a first detection result of tab defect detection based on the first image and a second detection result of tab defect detection based on the second image, wherein the first detection result and the second detection result indicate: whether there is a first type defect in the tab in the tab stack; and the position of the first type defect if the first type defect exists, the first type defect includes an abnormality in the tab line, and the position of the first type defect indicates the relative position of the first type defect at the height of the tab; 203: determining whether there is a folded-to-membrane area defect in the tab stack based on the first detection result and the second detection result.

[0045] In the above method, the first side surface and the second side surface can be either side surface of the same tab stack 11 or 12. The first side surface can be the left side surface and the second side surface can be the right side surface; alternatively, the first side surface can be the right side surface and the second side surface can be the left side surface. Furthermore, the above method can be performed on each of the tab stacks 11 and 12 to determine whether the tab stacks 11 and 12 of the battery cell 1 have a fold-over-film region defect. If neither tab stack 11 or 12 has a fold-over-film region defect, it can be determined that the battery cell 1 does not have a tab fold-over-film region defect.

[0046] In the present disclosure, tab line abnormalities refer to abnormalities in the edge lines of each layer of the tabs in the tab stack in the first image and the second image due to defects such as folding and wrinkling. Such abnormalities can be detected by analyzing the images using an algorithm such as an AI algorithm. In one embodiment, for example, the relative position of the first type of defect at the height of the tab can represent the distance (for example, expressed in millimeters or centimeters) from the position of the defect to the root of the tab (i.e., the position of the tab stack 11 and 12 flush with the surface of the battery cell 1), or it can represent the ratio of the distance from the position of the defect to the root of the tab to the height of the tab.

[0047] In the above embodiment, as an example, if the distance from the location of the defect to the base of the tab is less than or equal to a specific distance threshold (e.g., 1 mm, 2 mm, etc.), it can be determined that the tab stack has a fold-over-film region defect. As another example, if the defect location is represented by the above ratio, if the above ratio in one or both of the first and second test results is less than or equal to a specific ratio threshold (e.g., 1 / 5, 1 / 4, etc.), it can be determined that the tab stack has a fold-over-film region defect.

[0048] In the above embodiment, since the defect detection results and defect positions of the first image and the second image of the two sides of the tab stack are comprehensively considered to determine whether the tab stack has a fold-to-film area defect, it is possible to avoid judging a slight fold or wrinkle defect of a certain layer of the tab as a serious defect (i.e., a fold-to-film area defect), thereby significantly improving the yield of the battery cell and reducing the workload of manual secondary re-judgment.

[0049] More specifically, in previous techniques, only one-side images of the tab stack were used to determine whether defects such as folding or wrinkling were present. If such defects were present, the tab stack was considered defective and the battery cell was deemed unqualified. In the above-described embodiments of the present disclosure, if a tab in the tab stack has tab line abnormalities, which may indicate defects such as folding or wrinkling, then images of both sides of each tab stack are further used to comprehensively determine whether a fold-to-film region defect is likely present. This allows the severity of tab line abnormalities to be differentiated, allowing many tab line abnormalities that do not materially affect the safety of the battery cell during subsequent production and use to be deemed acceptable.

[0050] In one embodiment, the tab defect detection method may further include: in response to determining that the tab stack has a fold-over to film region defect, determining that the tab defect detection result of the battery cell is unqualified.

[0051] Therefore, the tab defect detection result of the battery cell is determined to be unqualified only when it is determined that the tab stack has a defect of folding to the membrane area. This can improve the yield of qualified products and reduce unnecessary manual secondary re-judgment.

[0052] In one embodiment, step 203 of determining whether the tab stack has a fold-over to film region defect may include: when both the first test result and the second test result indicate that a tab in the tab stack has a first type defect, determining whether the first type defect indicated in the first test result and the first type defect indicated in the second test result correspond to the same tab; when the first type defect indicated in the first test result and the first type defect indicated in the second test result correspond to the same tab, determining whether the position of the first type defect indicated in the first test result and the position of the first type defect indicated in the second test result meet a first standard; and when the first standard is met, determining that the tab stack has a fold-over to film region defect.

[0053] In the above embodiment, for example, whether the first type defects in the first detection result and the second detection result correspond to the same tab (i.e., tabs in the same layer) can be determined based on which tab layer in the image of the tab stack the tab corresponding to the first type defect is located.

[0054] Since the first type of defect indicated in the first test result and the first type of defect indicated in the second test result correspond to the same pole lug, the appropriate defect location judgment standard (for example, the above-mentioned first standard) that conforms to the actual situation can be determined based on the original shape (that is, the shape without defects such as folding or wrinkling) and size of the same pole lug and actual engineering experience, and then the presence of a fold-to-membrane area defect in the pole lug stack can be determined based on whether the position of the first type of defect indicated in the first test result and the position of the first type of defect indicated in the second test result meet the defect location judgment standard, thereby improving the accuracy of the fold-to-membrane area defect judgment.

[0055] In the above embodiment, as an example, the first criterion may indicate that the distance between the location of the first type defect indicated in the first test result and the base of the tab, and the distance between the location of the first type defect indicated in the second test result and the base of the tab, are both less than or equal to a specific distance threshold (e.g., 1 mm, 2 mm, etc.). As another example, where the defect location is represented by the above ratio, the first criterion may indicate that the ratio of the distance between the location of the first type defect indicated in the first test result and the base of the tab relative to the height of the tab, and the ratio of the distance between the location of the first type defect indicated in the second test result and the base of the tab relative to the height of the tab, both do not exceed a first threshold. The first threshold may be less than or equal to 1 / 2. For example, the first threshold may be 1 / 2, 2 / 5, etc.

[0056] FIG3 is a schematic diagram illustrating a defect location determination criterion according to an embodiment of the present disclosure. This defect location determination criterion is a specific example of the first criterion in the above-described embodiment. In this example, as shown in FIG3 , if the first-type defects on the left and right sides of the tab stack 12 correspond to the same tab, and the ratio of the distance of the first-type defects on both the left and right sides from the base of the tab to the height of the tab does not exceed a first threshold value (e.g., 1 / 2H as shown in FIG3 ), the end of the tab may be folded over or contact the membrane 13 on the surface of the battery cell 1.

[0057] In the above embodiment, as another example, when the defect position is represented by the above ratio, the first criterion may indicate that the ratio of the distance from the base of the tab to the height of the tab of the first type defect indicated in the first test result to the ratio of the distance from the base of the tab to the height of the tab does not exceed a second threshold, and the ratio of the distance from the base of the tab to the height of the tab of the first type defect indicated in the second test result to the ratio of the distance from the base of the tab to the height of the tab does not exceed a third threshold. The second threshold may be, for example, a threshold greater than 1 / 2 (e.g., 4 / 5, 2 / 3, etc.), and the third threshold may be, for example, a threshold less than 1 / 2 (e.g., 1 / 3, 2 / 5, etc.).

[0058] FIG4 is a schematic diagram illustrating a defect location determination criterion according to another embodiment of the present disclosure. This defect location determination criterion is another specific example of the first criterion in the above-mentioned embodiment. In this example, as shown in FIG4 , when the first type defects on the left and right sides of the tab stack 12 correspond to the same tab, if the ratio of the distance from the base of the tab to the height of the tab indicated in the first test result to the distance from the base of the tab to the height of the tab does not exceed a second threshold value (e.g., 4 / 5H as shown on the left side of the tab stack 12 in FIG4 ), and the ratio of the distance from the base of the tab to the height of the tab indicated in the second test result to the distance from the base of the tab to the height of the tab does not exceed a third threshold value (e.g., 1 / 3H as shown on the right side of the tab stack 12 in FIG4 ), then the end of the tab is likely to be folded over or in contact with the membrane 13 on the surface of the battery cell 1.

[0059] Note that the dashed triangle shown in FIG4 merely schematically illustrates one possible folding condition of a tab in a certain layer of the tab stack 12. In practice, depending on the original shape of the tab and the folding condition, the folded portion of a tab in a certain layer may be any other shape, such as a partial shape of a trapezoid, a partial shape of a rectangle, or other polygonal or irregular shapes.

[0060] According to one embodiment of the present disclosure, the first and second test results can also indicate whether the tab stack has a second type of defect, wherein the second type of defect can include a missing tab line. In a side view of the tab stack, when a tab is completely folded or retracted, it is characterized by a missing tab line, which can also be referred to as a missing tab or tab layer.

[0061] According to the above embodiment, when there is a missing tab line, the situation of the missing tab and the location of the first type of defect can be comprehensively considered to determine whether the tab stack has a folded-to-film area defect, thereby determining whether the defect exists more comprehensively and accurately.

[0062] According to one embodiment of the present disclosure, determining whether a tab stack has a fold-over-film region defect may include: if a first test result indicates the presence of a first type defect and a second test result indicates the presence of a second type defect, determining whether the first type defect and the second type defect correspond to the same tab; if the first type defect and the second type defect correspond to the same tab, determining whether a ratio of a distance from a location of the first type defect indicated in the first test result to a base of the tab relative to a height of the tab does not exceed a fourth threshold; and if the ratio does not exceed the fourth threshold, determining that the tab stack has a fold-over-film region defect. The fourth threshold may be, for example, a ratio less than or equal to 1 / 3.

[0063] According to the above embodiment, when there is a missing tab line, based on a specific defect position threshold, the situation of the missing tab and the location of the first type of defect are comprehensively considered to determine whether the tab stack has a folded-over to the membrane area defect, thereby determining whether the defect exists more comprehensively and accurately.

[0064] FIG5 is a schematic diagram illustrating a defect location determination criterion in another embodiment of the present disclosure. This defect location determination criterion is an example of the determination criteria in the aforementioned embodiment for a case where a tab line is missing on one side of a tab stack. In this example, as shown in FIG5 , a second-type defect (i.e., a missing tab line, also known as a missing tab or tab layer) exists on the left side of the tab stack, and a first-type defect (i.e., a tab line abnormality such as a fold or wrinkle) exists on the right side. The second-type defect on the left side of the tab stack 12 shown in FIG5 and the first-type defect on the right side correspond to the same tab. In this case, if the ratio of the distance from the base of the tab to the height of the tab indicated in the first detection result on the right side does not exceed a fourth threshold (e.g., 1 / 3H as shown on the right side of the tab stack 12 in FIG5 ), then the end of the tab is likely to be folded over or in contact with the membrane 13 on the surface of the battery cell 1.

[0065] According to one embodiment of the present disclosure, determining whether a tab stack has a fold-over-film region defect may include: when a first test result indicates the presence of a first type defect and a second test result indicates the tab corresponding to the first type defect does not have either the first type defect or the second type defect, determining whether a ratio of a distance from a location of the first type defect indicated in the first test result to a base of the tab relative to a height of the tab does not exceed a fifth threshold; and if the ratio does not exceed the fifth threshold, determining that the tab stack has a fold-over-film region defect. The fifth threshold may be, for example, a ratio less than or equal to 1 / 5.

[0066] According to the above embodiment, if a first-type defect exists on one side of a tab stack, and the tab corresponding to the first-type defect has neither a first-type defect nor a second-type defect on the other side, it can be determined whether the ratio of the distance from the location of the first-type defect on the one side to the base of the tab relative to the height of the tab does not exceed a fifth threshold. If this ratio does not exceed the fifth threshold, then the tab stack likely has a fold-over-to-film region defect. Thus, if a first-type defect exists on one side of a tab but not on the other, the presence of a fold-over-to-film region defect can be determined by comprehensively considering the conditions on both sides, thereby more comprehensively and accurately determining whether the defect exists.

[0067] FIG6 shows a schematic diagram for illustrating a defect location determination criterion in another embodiment of the present disclosure. The defect location determination criterion is an example of a determination criterion in the above embodiment in which a first type defect exists on one side of the tab stack, and the tab corresponding to the first type defect does not have either a first type defect or a second type defect on the other side. In this example, as shown in FIG6 , the tab in the tab stack does not have a first type defect or a second type defect on the left side, and the tab has a first type defect on the right side. If the ratio of the distance of the position of the first type defect on the right side from the root of the tab to the height of the tab does not exceed the fifth threshold value (for example, 1 / 5H shown on the right side of the tab stack 12 in FIG6 ), then the end of the tab may be folded over or contact the membrane 13 on the surface of the battery cell 1.

[0068] FIG7 is a method for detecting tab defects of a battery cell according to another embodiment of the present disclosure, as shown in FIG7 , comprising the following steps:

[0069] Step 701: Using a visual defect AI detection algorithm, the obtained left and right images of the tab stack of the battery cell are respectively inspected to obtain corresponding inspection results;

[0070] Step 702: Determine defect results of the left and right images of the tab stack based on the detection results;

[0071] Step 703: Output defect results of the left and right images of the tab stack respectively.

[0072] FIG8 shows a method for determining whether a tab is folded into a film region according to an embodiment of the present disclosure, and as shown in FIG8 , the method includes the following steps:

[0073] Step 801, obtaining a left side image of a tab stack of a battery cell;

[0074] Step 802, obtaining a right side image of the tab stack of the battery cell;

[0075] Step 803: Use the visual defect AI detection algorithm to detect the left image and the right image respectively to obtain detection results;

[0076] Step 804: Determine whether both the left and right images have visual defects based on the detection results. If so, that is, both have visual defects, and proceed to step 805. If not, that is, there is a visual defect on one side of the tab stack and the tab stack may be missing on the other side, and proceed to step 807.

[0077] Step 805, outputting the defect locations in the left and right images respectively;

[0078] Step 806: Determine whether the defect positions in the left and right images meet the set values; if so, that is, they meet the set values, an NG result is output; if not, that is, they do not meet the set values, an OK result is output;

[0079] Here, the set value is within the area of ​​1 / 2 tab height from the tab base, or within the area of ​​4 / 5 tab height from the tab base on one side, and within the area of ​​1 / 3 tab height from the tab base on the other side.

[0080] Step 807, determining whether there is a missing tab on the other side of the tab stack; if so, that is, there is a missing tab, proceeding to step 808; if not, that is, there is no missing tab, proceeding to step 810;

[0081] Step 808, outputting the location where the tab is missing;

[0082] Step 809, determining whether the position of the missing tab meets the set value; if so, that is, it meets the set value, an NG result is output; if not, that is, it does not meet the set value, an OK result is output;

[0083] Here, the set value is within the area of ​​1 / 3 of the tab height from the tab base.

[0084] Step 810 , outputting a location where a visual defect exists on one side of the tab stack;

[0085] Step 811, determine whether the position of the visual defect meets the set value; if so, it meets the set value and outputs an NG result; if not, it does not meet the set value and outputs an OK result.

[0086] Here, the set value is within the area of ​​1 / 5 of the tab height from the tab base.

[0087] The above describes several specific examples of the method for detecting tab defects in battery cells according to the present disclosure. Through the above-described tab defect detection method, a tab stack is determined to have a fold-to-film defect only when any of the aforementioned multiple situations in which a tab or tab layer in the tab stack may have a fold-to-film defect occurs. Thus, a large number of other cases in which only minor defects in the tab or tab layer exist are determined to have no fold-to-film defect and are deemed qualified. This can significantly improve the yield rate of battery cells and reduce the cost of manual secondary re-determination of battery cell qualification.

[0088] According to another aspect of the present disclosure, as shown in FIG9 , a tab defect detection device 300 for a battery cell 1 is further provided, comprising: a first camera 301, located at a position opposite to a first side surface of a tab stack of the battery cell 1 (the right side surface of the tab stack 12 in the figure), for capturing a first image of the first side surface; a second camera 302, located at a position opposite to a second side surface of the tab stack (the left side surface of the tab stack 12 in the figure), for capturing a second image of the second side surface, wherein the first side surface and the second side surface are two surfaces parallel to the stacking direction of the tab stack and extending along the height direction of the tab in the tab stack; a controller 303, communicating with the first camera 301 and the second camera 302, for obtaining the first image and the second image. The processor 304 is in communication with the controller 303 and is configured to perform tab defect detection based on the first image to obtain a first detection result; and perform tab defect detection based on the second image to obtain a second detection result, wherein the first detection result and the second detection result indicate: whether the tab in the tab stack has a first type of defect; and the position of the first type of defect when the first type of defect exists, wherein the first type of defect includes tab line abnormality, and the position of the first type of defect indicates the relative position of the first type of defect at the height of the tab; the controller 303 is further configured to determine whether the tab stack has a fold-over to membrane area defect based on the first detection result and the second detection result.

[0089] In FIG. 9 , in order to highlight the tab defect detection apparatus 300 as the main drawing object, the battery cell 1 is drawn smaller, and the second tab stack 12 having defects and the first tab stack 11 having no defects are shown.

[0090] In the above embodiment, the controller 303 may be, for example, a programmable logic controller (PLC), configured to perform logical judgment operations and control the first camera 301 and the second camera 302 . For example, the controller 303 may instruct the first camera 301 and the second camera 302 to capture and transmit images. In addition, the controller 303 may also send instructions to and control other devices on the production line of the battery cell 1 .

[0091] The processor 304 can be, for example, a central processing unit (CPU), and can receive the first image and the second image from the first camera 301 and the second camera 302 from the controller 303, and perform operations such as image recognition, analysis, and defect detection on the first image and the second image by using algorithms such as AI image analysis algorithms, and can also send recognition results and detection results to the controller 303.

[0092] In the above embodiment, since the tab defect detection equipment 300 comprehensively considers the defect detection results and defect positions of the first image and the second image of the two sides of the tab stack to determine whether the tab stack has a fold-over to the membrane area defect, it can avoid judging a slight fold or wrinkle defect of a certain layer of the tab as a serious defect (i.e., a fold-over to the membrane area defect), thereby significantly improving the yield of the battery cell and reducing the workload of manual secondary re-judgment.

[0093] According to one embodiment of the present disclosure, in the tab defect detection device 300 , the controller 303 may also be configured to determine that the tab defect detection result of the battery cell 1 is unqualified in response to determining that the tab stack has a fold-to-film region defect.

[0094] According to one embodiment of the present disclosure, in the tab defect detection device 300, in order to determine whether the tab stack has a fold-over to film region defect, the controller 303 can be further used to determine whether the first type defect indicated in the first detection result and the first type defect indicated in the second detection result correspond to the same tab when both the first detection result and the second detection result indicate that the tab in the tab stack has a first type defect; when the first type defect indicated in the first detection result and the first type defect indicated in the second detection result correspond to the same tab, determine whether the position of the first type defect indicated in the first detection result and the position of the first type defect indicated in the second detection result meet a first standard; and when the first standard is met, determine whether the tab stack has a fold-over to film region defect.

[0095] In the above embodiment, for example, whether the first type defects in the first detection result and the second detection result correspond to the same tab (i.e., tabs in the same layer) can be determined based on which tab layer in the image of the tab stack the tab corresponding to the first type defect is located.

[0096] Since the first type of defect indicated in the first test result and the first type of defect indicated in the second test result correspond to the same pole lug, the appropriate defect location judgment standard (for example, the above-mentioned first standard) that conforms to the actual situation can be determined based on the original shape (that is, the shape without defects such as folding or wrinkling) and size of the same pole lug and actual engineering experience, and then the presence of a fold-to-membrane area defect in the pole lug stack can be determined based on whether the position of the first type of defect indicated in the first test result and the position of the first type of defect indicated in the second test result meet the defect location judgment standard, thereby improving the accuracy of the fold-to-membrane area defect judgment.

[0097] In the above embodiment, as an example, the first criterion may indicate that the distance between the location of the first type defect indicated in the first test result and the root of the tab, and the distance between the location of the first type defect indicated in the second test result and the root of the tab are both less than or equal to a specific distance threshold (e.g., 1 mm, 2 mm, etc.). As another example, when the defect location is represented by the above ratio, the first criterion may indicate that the ratio of the distance between the location of the first type defect indicated in the first test result and the root of the tab relative to the height of the tab, and the ratio of the distance between the location of the first type defect indicated in the second test result and the root of the tab relative to the height of the tab, do not exceed a first threshold, and the first threshold may be less than or equal to 1 / 2. For example, the first threshold may be 1 / 2, 2 / 5, etc.

[0098] According to one embodiment of the present disclosure, in the tab defect detection device 300, in order to determine whether the position of the first type defect indicated in the first detection result and the position of the first type defect indicated in the second detection result meet the first standard, the controller 303 can be further used to: determine whether the ratio of the distance from the position of the first type defect indicated in the first detection result to the root of the tab to the height of the tab does not exceed a second threshold; and determine whether the ratio of the distance from the position of the first type defect indicated in the second detection result to the root of the tab to the height of the tab does not exceed a third threshold, wherein the second threshold is greater than 1 / 2 (for example, 4 / 5, 2 / 3, etc.), and the third threshold is less than 1 / 2 (for example, 1 / 3, 2 / 5, etc.).

[0099] According to an embodiment of the present disclosure, in the tab defect detection device 300 , the first detection result and the second detection result may further indicate whether the tab stack has a second type defect, wherein the second type defect may include missing tab lines.

[0100] According to the above embodiment, the tab defect detection device 300 can determine whether there is a folded-to-film area defect in the tab stack when there is a missing tab line by comprehensively considering the situation of the missing tab and the location of the first type of defect, thereby determining whether the defect exists more comprehensively and accurately.

[0101] According to one embodiment of the present disclosure, in the tab defect detection device 300, to determine whether a tab stack has a fold-over-film region defect, the controller 303 may further be configured to: if a first detection result indicates the presence of a first type defect and a second detection result indicates the presence of a second type defect, determine whether the first type defect and the second type defect correspond to the same tab; if the first type defect and the second type defect correspond to the same tab, determine whether the ratio of the distance from the location of the first type defect indicated in the first detection result to the base of the tab relative to the height of the tab does not exceed a fourth threshold; and if the ratio does not exceed the fourth threshold, determine that the tab stack has a fold-over-film region defect. The fourth threshold may be, for example, a ratio less than or equal to 1 / 3.

[0102] According to the above embodiment, the tab defect detection device 300 can determine whether the tab stack has a folded-over to the membrane area defect based on a specific defect position threshold when there is a missing tab line, taking into account the situation of the missing tab and the location of the first type of defect, thereby determining whether the defect exists more comprehensively and accurately.

[0103] According to one embodiment of the present disclosure, in the tab defect detection device 300, to determine whether a tab stack has a fold-over-film region defect, the controller 303 may further be configured to: when a first detection result indicates the presence of a first type defect and a second detection result indicates the tab corresponding to the first type defect does not have either the first type defect or the second type defect, determine whether the ratio of the distance from the location of the first type defect indicated in the first detection result to the base of the tab to the height of the tab does not exceed a fifth threshold; and if the ratio does not exceed the fifth threshold, determine that the tab stack has a fold-over-film region defect. The fifth threshold may be, for example, a ratio less than or equal to 1 / 5.

[0104] According to the above embodiment, in the tab defect detection device 300, if a first-type defect exists on one side of a tab stack, and the tab corresponding to the first-type defect has neither a first-type defect nor a second-type defect on the other side, the controller 303 can determine whether the ratio of the distance from the location of the first-type defect on the one side to the base of the tab relative to the height of the tab does not exceed a fifth threshold. If this ratio does not exceed the fifth threshold, then the tab stack likely has a fold-over-film region defect. Thus, if a first-type defect exists on one side of a tab but not on the other, the presence of a fold-over-film region defect can be determined by comprehensively considering the conditions on both sides, thereby more comprehensively and accurately determining whether the defect exists.

[0105] The first to fifth thresholds and all other thresholds described in this disclosure are adjustable parameters that can be specifically determined by those skilled in the art based on the shape and size of the specific tab and engineering practice experience, and all the above thresholds are merely examples, which do not constitute a limitation on the scope of patent protection of this disclosure.

[0106] It should be understood that “one embodiment” or “an embodiment” mentioned throughout the specification means that specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present disclosure. Therefore, “in one embodiment” or “in an embodiment” appearing throughout the specification does not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner. It should be understood that in the various embodiments of the present disclosure, the size of the serial numbers of the above-mentioned steps / processes does not mean the order of execution, and the execution order of each step / process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present disclosure. The serial numbers of the embodiments of the present disclosure are for description only and do not represent the advantages and disadvantages of the embodiments.

[0107] It should be noted that, in the disclosure, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not preclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0108] In the several embodiments provided in the present disclosure, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as: multiple units or components can be combined, or can be integrated into another system, or some features can be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the components shown or discussed can be through some interfaces, and the indirect coupling or communication connection of the devices or units can be electrical, mechanical or other forms.

[0109] The units described above as separate components may or may not be physically separate, and the components shown as units may or may not be physical units; they may be located in one place or distributed across multiple network units; some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment. In addition, the functional units in the various embodiments of the present disclosure may all be integrated into one processing unit, or each unit may be separately used as a unit, or two or more units may be integrated into one unit; the above-mentioned integrated units may be implemented in the form of hardware or in the form of hardware plus software functional units.

[0110] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present disclosure, and they should all be included in the scope of the claims and specification of the present disclosure. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present disclosure is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A method for detecting ear defects of a battery cell, comprising: Obtaining a first image of a first side of an ear stack of the battery cell and a second image of a second side of the ear stack opposite to the first side, wherein the first side and the second side are two surfaces parallel to the stacking direction of the ear stack and extending along the height direction of the ears in the ear stack; Obtaining a first detection result for detecting ear defects based on the first image and a second detection result for detecting ear defects based on the second image, wherein the first detection result and the second detection result indicate whether there are first-type defects in the ears in the ear stack; and the positions of the first-type defects, the first-type defects include abnormal ear lines, and the positions of the first-type defects indicate the relative positions of the first-type defects in the height of the ears; and Based on the first detection result and the second detection result, determining whether there is a defect of the ear stack folding into the film area.

2. The method according to claim 1, wherein, It further comprises: In response to determining that there is a defect of the ear stack folding into the film area, determining that the detection result of the ear defects of the battery cell is unqualified.

3. The method according to claim 1 or 2, wherein The determining whether there is a defect of the ear stack folding into the film area includes: When both the first detection result and the second detection result indicate that there are first-type defects in the ears in the ear stack, determining whether the first-type defects indicated in the first detection result and the first-type defects indicated in the second detection result correspond to the same ear; When the first-type defects indicated in the first detection result and the first-type defects indicated in the second detection result correspond to the same ear, determining whether the position of the first-type defects indicated in the first detection result and the position of the first-type defects indicated in the second detection result meet a first standard; and When the first standard is met, determining that there is a defect of the ear stack folding into the film area.

4. The method according to any one of claims 1 to 3, wherein, The determining whether the position of the first-type defects indicated in the first detection result and the position of the first-type defects indicated in the second detection result meet the first standard includes: Determining whether the ratio of the distance from the position of the first-type defects indicated in the first detection result to the root of the ear to the height of the ear does not exceed a first threshold; and Determining whether the ratio of the distance from the position of the first-type defects indicated in the second detection result to the root of the ear to the height of the ear does not exceed the first threshold, wherein the first threshold is less than or equal to 1 / 2.

5. The method according to claim 3 or 4, wherein, The determining whether the position of the first-type defects indicated in the first detection result and the position of the first-type defects indicated in the second detection result meet the first standard further includes: Determining whether the ratio of the distance from the position of the first-type defects indicated in the first detection result to the root of the ear to the height of the ear does not exceed a second threshold; and Determine whether the ratio of the distance between the position of the first type of defect indicated in the second detection result and the root of the tab to the height of the tab does not exceed a third threshold value. Wherein, the second threshold value is greater than 1 / 2, and the third threshold value is less than 1 / 2.

6. The method according to any one of claims 1 to 5, wherein The first detection result and the second detection result also indicate whether there is a second type of defect in the tab stack, wherein the second type of defect includes the absence of tab lines.

7. The method according to claim 6, wherein The determination of whether there is a defect of the tab stack being folded to the film area includes: When the first detection result indicates the existence of a first type of defect and the second detection result indicates the existence of a second type of defect, determine whether the first type of defect and the second type of defect correspond to the same tab; When the first type of defect and the second type of defect correspond to the same tab, determine whether the ratio of the distance between the position of the first type of defect indicated in the first detection result and the root of the tab to the height of the tab does not exceed a fourth threshold value; and When it does not exceed the fourth threshold value, determine that there is a defect of the tab stack being folded to the film area.

8. The method according to claim 6 or 7, wherein The determination of whether there is a defect of the tab stack being folded to the film area further includes: When the first detection result indicates the existence of a first type of defect and the second detection result indicates that there are no first type of defects and second type of defects in the tab corresponding to the first type of defect, determine whether the ratio of the distance between the position of the first type of defect indicated in the first detection result and the root of the tab to the height of the tab does not exceed a fifth threshold value; and When it does not exceed the fifth threshold value, determine that there is a defect of the tab stack being folded to the film area.

9. A tab defect detection device for a battery cell includes: A first camera, located at a position opposite to the first side of the tab stack of the battery cell, for taking a first image of the first side; A second camera, located at a position opposite to the second side of the tab stack, for taking a second image of the second side, wherein the first side and the second side are two surfaces parallel to the stacking direction of the tab stack and extending along the height direction of the tabs in the tab stack; A controller, communicatively connected to the first camera and the second camera, for obtaining the first image and the second image, and transmitting the first image and the second image to a processor; A processor, communicatively connected to the controller, for performing tab defect detection based on the first image to obtain a first detection result; and performing tab defect detection based on the second image to obtain a second detection result, wherein the first detection result and the second detection result indicate whether there is a first type of defect in the tabs in the tab stack; and the position of the first type of defect, wherein the first type of defect includes abnormal tab lines, and the position of the first type of defect indicates the relative position of the first type of defect in the height of the tab. The controller is further configured to determine whether there is a defect that the tab stack is folded into the film area based on the first detection result and the second detection result.

10. The device according to claim 9, wherein the controller is further configured to determine that the tab defect detection result of the battery cell is unqualified in response to determining that there is a defect that the tab stack is folded into the film area.

11. The device according to claim 9 or 10, wherein, To determine whether there is a defect that the tab stack is folded into the film area, the controller is further configured to: When both the first detection result and the second detection result indicate that there is a first type of defect in the tabs in the tab stack, determine whether the first type of defect indicated in the first detection result and the first type of defect indicated in the second detection result correspond to the same tab; When the first type of defect indicated in the first detection result and the first type of defect indicated in the second detection result correspond to the same tab, determine whether the position of the first type of defect indicated in the first detection result and the position of the first type of defect indicated in the second detection result meet a first criterion; and When the first criterion is met, determine that there is a defect that the tab stack is folded into the film area.

12. The apparatus according to any one of claims 9 to 11, wherein, To determine whether the position of the first type of defect indicated in the first detection result and the position of the first type of defect indicated in the second detection result meet the first criterion, the controller is further configured to: Determine whether the ratio of the distance of the position of the first type of defect indicated in the first detection result from the root of the tab to the height of the tab does not exceed a first threshold; and Determine whether the ratio of the distance of the position of the first type of defect indicated in the second detection result from the root of the tab to the height of the tab does not exceed the first threshold, where the first threshold is less than or equal to 1 / 2.

13. The device according to claim 11 or 12, wherein, For determining whether the position of the first type of defect indicated in the first detection result and the position of the first type of defect indicated in the second detection result meet the first criterion, the controller is further configured to: Determine whether the ratio of the distance of the position of the first type of defect indicated in the first detection result from the root of the tab to the height of the tab does not exceed a second threshold; and Determine whether the ratio of the distance of the position of the first type of defect indicated in the second detection result from the root of the tab to the height of the tab does not exceed a third threshold, where the second threshold is greater than 1 / 2 and the third threshold is less than 1 / 2.

14. The device according to any one of claims 9 to 13, wherein, The first detection result and the second detection result also indicate whether there is a second type of defect in the tab stack, where the second type of defect includes missing tab lines.

15. The device according to claim 14, wherein To determine whether there is a defect that the tab stack is folded into the film area, the controller is further configured to: When the first detection result indicates the existence of a first type of defect and the second detection result indicates the existence of a second type of defect, determine whether the first type of defect and the second type of defect correspond to the same tab; When the first type of defect and the second type of defect correspond to the same tab, determine whether the ratio of the distance from the position of the first type of defect indicated in the first detection result to the root of the tab to the height of the tab does not exceed a fourth threshold value; and When it does not exceed the fourth threshold value, determine that there is a defect of the tab stack folding to the film area.

16. The device according to claim 14 or 15, wherein, To determine whether there is a defect of the tab stack folding to the film area, the controller is further configured to: When the first detection result indicates the existence of a first type of defect and the second detection result indicates that there are no first type of defects and second type of defects in the tab corresponding to the first type of defect, determine whether the ratio of the distance from the position of the first type of defect indicated in the first detection result to the root of the tab to the height of the tab does not exceed a fifth threshold value; and When it does not exceed the fifth threshold value, determine that there is a defect of the tab stack folding to the film area.

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