Method for removing bad pole pieces, die-cutting device, winding device and battery production system

Abstract

The present application relates to the technical field of defect detection, and provides a method for rejecting bad pole pieces, a die-cutting device, a winding device and a battery production system. The method for rejecting bad pole pieces comprises the following steps: performing defect detection on the pole piece material strip; based on detecting the existence of defects in the pole piece unit, affixing a defect label to the defective pole piece unit, and cutting at least one pole ear of one of the pole piece units to form a structural defect mark; performing defect label detection and structural defect mark detection on the pole ears of the pole piece units in the process of being wound into an electrode assembly; based on detecting the existence of defective labels in the pole piece units, separately winding the pole piece units affixed with the defective labels; based on detecting the existence of structural defect marks on the pole ears, identifying the defective pole piece units; judging whether the defective pole piece units are separately wound, and if not separately wound, rejecting the electrode assembly formed by winding the defective pole piece units.

Description

Technical Field

[0001] The present application relates to the field of defect detection technology, and in particular provides a method for rejecting bad pole pieces, a die-cutting device, a winding device and a battery production system. Background Art

[0002] Energy conservation and emission reduction are the key to the sustainable development of the automobile industry. Electric vehicles have become an important part of the sustainable development of the automobile industry due to their advantages in energy conservation and environmental protection. For electric vehicles, battery technology is an important factor in their development.

[0003] During the production process of battery cells, the pole pieces need to be wound to form electrode assemblies for subsequent assembly. In order to reduce the defective rate of battery cells, the defects of the pole pieces need to be marked before winding the pole pieces; once defects are found, a section of the pole piece unit that can be wound to form a complete electrode assembly needs to be scrapped.

[0004] In the related art, the method of marking the defects of the electrode piece is mainly to use a labeling machine to affix a defective label to the defective electrode piece unit; however, during the labeling operation of the labeling machine, the defective label is prone to problems such as missing or falling off, which will cause the defective electrode piece unit to be wound to form an electrode assembly, thereby increasing the defective rate of the produced battery cells. Summary of the invention

[0005] The purpose of the embodiments of the present application is to provide a method for rejecting defective pole pieces, a die-cutting device, a winding device and a battery production system, aiming to solve the problem of missing or falling labels when labeling defective pole piece units in related technologies.

[0006] To achieve the above purpose, the technical solution adopted in the embodiment of the present application is:

[0007] In a first aspect, an embodiment of the present application provides a method for rejecting bad electrode pieces, comprising:

[0008] Defect detection is performed on a pole piece strip having a plurality of continuously distributed pole piece units;

[0009] Based on the detection of the defect in the pole piece unit, a defect label is attached to the defective pole piece unit, and at least one pole ear of one of the pole piece units is cut to form a structural defect mark;

[0010] Conduct defect label detection on the electrode unit in the process of being wound into an electrode assembly;

[0011] Based on the detection of the defective label on the pole piece unit, the pole piece unit with the defective label is wound separately;

[0012] Perform structural defect identification detection on the pole lugs of the pole piece units in the process of being wound into an electrode assembly;

[0013] Based on the detection of the structural defect mark of the pole ear, the defective pole piece unit is identified;

[0014] It is determined whether the defective pole piece unit is wound separately. If not, the electrode assembly formed by winding the defective pole piece unit is discarded.

[0015] Beneficial effects of the embodiments of the present application: The method for removing defective pole pieces provided in the embodiments of the present application, after detecting defects in the pole piece unit, forms a structural defect mark by attaching a defect label to the defective pole piece unit and cutting at least one pole ear of one of the pole piece units; thereby, in the process of identifying the defective pole piece unit by detecting the defective label and winding it separately, if the defective label falls off or is missed, the defective pole piece unit will not be wound separately but will be wound to form an electrode assembly; at this time, the defective pole piece unit is identified by detecting the structural defect mark and it is determined whether the defective pole piece unit is wound separately. If it is wound separately, it means that the defective label is attached normally. If it is not wound separately, it means that the defective label falls off or is missed. The electrode assembly formed by winding the defective pole piece unit is removed to reduce the defective rate of the battery cells finally produced.

[0016] In some embodiments, the specific steps of cutting at least one pole ear of one pole piece unit and forming a structural defect mark include:

[0017] At least one pole ear of a defective pole piece unit is cut to form a structural defect mark.

[0018] By adopting the above technical solution, the pole ear of the defective pole piece unit can be cut to form a structural defect mark, so that the pole piece unit where the pole ear with the structural defect mark is located is the defective pole piece unit.

[0019] In some embodiments, the specific steps of identifying a defective pole piece unit include:

[0020] After identifying that the pole lug has a structural defect mark, it is determined that the pole piece unit where the pole lug is located is a defective pole piece unit.

[0021] By adopting the above technical solution, when it is identified that a pole lug has a structural defect mark, it can be determined that the pole piece unit where the pole lug with the structural defect mark is located has a defect.

[0022] In some embodiments, the specific steps of cutting at least one pole ear of one pole piece unit and forming a structural defect mark include:

[0023] At least one pole ear of the next pole piece unit distributed in the pole piece unit with defects is cut to form a structural defect mark.

[0024] By adopting the above technical solution, the pole ear of the next pole piece unit distributed to the defective pole piece unit can be cut to form a structural defect mark, thereby, the next pole piece unit of the pole piece unit where the pole ear with the structural defect mark is located is the defective pole piece unit.

[0025] In some embodiments, the specific steps of identifying a defective pole piece unit include:

[0026] After the structural defect mark is identified, the next pole piece unit of the pole piece unit where the pole lug is located is determined to be a defective pole piece unit.

[0027] By adopting the above technical solution, when it is identified that a pole lug has a structural defect mark, it can be determined that the next pole piece unit of the pole piece unit where the pole lug with the structural defect mark is located has a defect.

[0028] In some embodiments, the defect detection of a pole piece strip having a plurality of continuously distributed pole piece units further includes:

[0029] The pole piece strip is die-cut to form pole ears, and at the same time, the last pole ear on the corresponding pole piece unit can be cut to form a structural defect mark.

[0030] By adopting the above-mentioned technical solution, the pole ear can be cut to form a structural defect mark during the die-cutting process of the pole piece material strip, which can effectively reduce the process flow; at the same time, cutting the last pole ear on the pole piece unit to form a structural defect mark can facilitate the observation of the structural defect mark.

[0031] In some embodiments, performing structural defect identification detection on the pole lug of the pole piece unit in the process of being wound into an electrode assembly includes:

[0032] Get the image of the tab to be tested.

[0033] Inputting the image of the pole lug to be tested into an image classification model to obtain a detection result of the image of the pole lug to be tested, wherein the image classification model is trained using a sample set, and the sample set includes pole lug images marked with multiple classification labels;

[0034] Multiple classification labels include defect type and defect location;

[0035] The detection result is at least one of multiple classification labels.

[0036] By adopting the above technical solution, information such as defect type and defect orientation can be determined based on the image of the tab to be tested.

[0037] In some embodiments, in the distribution direction of the pole piece units, the structural defect mark is located at at least one side corner of the pole lug.

[0038] By adopting the above technical solution, a structural defect mark can be formed by cutting at least one side corner of the pole lug.

[0039] In some embodiments, in the distribution direction of the pole piece unit, the structural defect mark forms a first straight edge, and in the distribution direction perpendicular to the pole piece unit, the structural defect mark forms a second straight edge; wherein an angle α is formed between the first straight edge and the second straight edge, 60°≤α≤120°.

[0040] By adopting the above technical solution, by limiting the angle α between the first straight edge and the second straight edge to be greater than or equal to 60° and less than or equal to 120°, the probability of the tab being folded due to the angle of the structural defect mark formed by cutting being too large or too small can be reduced.

[0041] In some embodiments, a chamfer is formed at a connection between the first straight edge and the second straight edge.

[0042] By adopting the above technical solution, the first straight edge and the second straight edge are cut to form a chamfer, so as to reduce the probability of excess material being generated between the first straight edge and the second straight edge.

[0043] In some embodiments, in a distribution direction perpendicular to the pole piece unit, the structural defect marker is located at an end of the pole ear that is opposite to the pole piece unit.

[0044] By adopting the above technical solution, a structural defect mark can also be formed by cutting at one end of the pole ear facing away from the pole piece unit.

[0045] In some embodiments, the structural defect identification includes a first identification hole and a second identification hole that are connected to each other, the first identification hole is connected to the outside in a distribution direction perpendicular to the pole piece unit; the second identification hole is an arc-shaped hole.

[0046] By adopting the above technical solution, the probability of excess material being generated in the second marking hole can be effectively reduced by cutting the inner second marking hole into an arc-shaped hole.

[0047] In some embodiments, the structural defect mark is an arc-shaped structural mark.

[0048] By adopting the above technical solution, the probability of forming waste material can be effectively reduced by cutting the structural defect mark to form an arc-shaped structural mark.

[0049] In some embodiments, in the distribution direction of the pole piece unit, the pole ear has a width D, the structural defect mark has a width d, and 1mm≤d≤3D / 4.

[0050] By adopting the above-mentioned technical solution, the width of the structural defect mark is limited to greater than or equal to 1 mm, so as to reduce the difficulty of cutting and the probability that the structural defect mark is too narrow and difficult to identify; at the same time, the width of the structural defect mark is limited to less than or equal to 3D / 4, so that the width of the structural defect mark does not exceed three quarters of the width of the pole ear, so as to reduce the probability of the pole ear folding.

[0051] In some embodiments, in a distribution direction perpendicular to the pole piece unit, the pole ear has a height H, the structural defect mark has a height h, and 1 mm≤h≤H / 2.

[0052] By adopting the above-mentioned technical solution, the height of the structural defect mark is limited to greater than or equal to 1 mm, so as to reduce the difficulty of cutting and the probability that the structural defect mark is too small to be difficult to identify; at the same time, the height of the structural defect mark is limited to less than or equal to H / 2, so that the height of the structural defect mark does not exceed half of the height of the pole ear, so as to reduce the probability of the pole ear folding.

[0053] In some embodiments, the structural defect marker is located in the middle of the tab.

[0054] By adopting the above technical solution, a hole-shaped structural defect mark can also be cut in the middle of the tab.

[0055] In a second aspect, the embodiment of the present application further provides a die-cutting device, comprising:

[0056] A winding unit, used for pulling the pole sheet strip along a preset direction;

[0057] The die-cutting unit is used to die-cut the pole ear on the pole piece strip to produce a plurality of continuously distributed pole piece units; the die-cutting unit is also used to cut the pole ear to form a structural defect mark;

[0058] The defect detection unit is used to detect the connection defects of the pole piece unit and feed back to the die-cutting unit for cutting to form a structural defect mark;

[0059] A marking unit, used to attach a defect label to a defective electrode unit;

[0060] A second control unit is communicatively connected with the winding unit, the die-cutting unit, the defect detection unit and the marking unit;

[0061] When the defect detection unit detects that a pole piece unit has a defect, the marking unit affixes a defect label to the defective pole piece unit, and the die-cutting unit cuts on the pole ear to form a structural defect mark.

[0062] Beneficial effects of the embodiments of the present application: The die-cutting device provided in the embodiments of the present application can utilize the die-cutting unit to die-cut the pole ears on the pole piece material strip. According to the feedback from the defect detection unit, the die-cutting unit can also simultaneously cut the pole ears to form a structural defect mark, and the marking unit can also affix a defect label to the defective pole piece unit, thereby facilitating the identification of defects and the removal of bad products in subsequent winding operations.

[0063] In a third aspect, the present application also provides a winding device, including:

[0064] Anode unwinding unit, used for unwinding anode pole pieces;

[0065] Cathode unwinding unit, used for unwinding cathode electrode sheet;

[0066] An isolation film unwinding unit, used for unwinding the isolation film;

[0067] A winding needle is used to separate the anode electrode sheet and the cathode electrode sheet with a separator and to wind them to prepare an electrode assembly;

[0068] A label detection unit, used to detect defective labels on the anode pole piece when the winding needle is winding the anode pole piece, and / or used to detect defective labels on the cathode pole piece when the winding needle is winding the cathode pole piece; wherein the defective labels include structural defect marks cut on the pole ears of the anode pole piece and / or the pole ears of the cathode pole piece and defective labels attached to the anode pole piece and / or the cathode pole piece;

[0069] The third control unit is communicatively connected with the anode unwinding unit, the cathode unwinding unit, the isolation film unwinding unit, the winding needle and the identification detection unit.

[0070] Beneficial effects of the embodiments of the present application: The winding device provided in the embodiments of the present application utilizes a label detection unit to identify defective labels so as to separately wind up defective cathode plates and / or anode plates.

[0071] In a fourth aspect, an embodiment of the present application further provides a battery production system, comprising a die-cutting device as described above and / or a winding device as described above.

[0072] Beneficial effects of the embodiments of the present application: The battery production system provided in the embodiments of the present application, based on the die-cutting device and / or the winding device as described above, has a lower defective rate of products produced by the battery production system. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or related technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0074] Figure 1 A flow chart of a method for rejecting bad electrode pieces provided in an embodiment of the present application;

[0075] Figure 2 A flowchart of the specific steps of detecting structural defects on the pole lugs of the pole piece unit in the process of being wound into an electrode assembly in the method for rejecting bad pole pieces provided in an embodiment of the present application;

[0076] Figure 3 A schematic diagram of the structure of a pole piece unit provided in an embodiment of the present application;

[0077] Figure 4 A schematic diagram of a structure in which a structure defect mark is formed at the top corner of a pole ear of a pole piece unit provided in an embodiment of the present application;

[0078] Figure 5 for Figure 4 A local enlarged schematic diagram of point A;

[0079] Figure 6 A schematic diagram of a structure in which another structural defect mark is formed at the top corner of the pole ear of the pole piece unit provided in an embodiment of the present application;

[0080] Figure 7 A schematic diagram of a structure in which a pole ear of a pole piece unit provided in an embodiment of the present application forms a structural defect mark on a side away from the pole piece unit;

[0081] Figure 8 A schematic diagram of a structure in which a structure defect mark is formed in the middle of a pole ear of a pole piece unit provided in an embodiment of the present application;

[0082] Fig. 9 A schematic diagram of a die-cutting device provided in an embodiment of the present application;

[0083] Fig.10 A schematic diagram of a winding device provided in an embodiment of the present application.

[0084] Among them, the reference numerals in the figure are:

[0085] 10. Pole sheet strip;

[0086] 100, pole piece unit; 110, pole ear; 111, structural defect mark; 111a, first straight edge; 111b, second straight edge; 111c, chamfer; 1111, first identification hole; 1112, second identification hole; 112, defect label;

[0087] X, distribution direction;

[0088] 1000. Die-cutting device;

[0089] 1100, winding unit; 1200, die-cutting unit; 1300, defect detection unit; 1400, marking unit; S, preset direction;

[0090] 2000, winding device;

[0091] 2100, anode unwinding unit; 2200, cathode unwinding unit; 2300, winding needle; 2400, label detection unit; 2410, sensor; 2420, visual sensing device. DETAILED DESCRIPTION

[0092] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0093] In the description of the present application, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", 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 present application 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 operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0094] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0095] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0096] At present, from the perspective of market development, the application of power batteries is becoming more and more extensive. Power batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, as well as military equipment and aerospace and other fields. With the continuous expansion of the application field of power batteries, the market demand is also constantly expanding.

[0097] During the production process of battery cells, the pole pieces need to be wound to form electrode assemblies for subsequent assembly. In order to reduce the defective rate of battery cells, the defects of the pole pieces need to be marked before winding the pole pieces; once defects are found, a section of the pole piece unit that can be wound to form a complete electrode assembly needs to be scrapped.

[0098] In the related art, the method of marking the defects of the electrode piece is mainly to use a labeling machine to affix a defective label to the defective electrode piece unit; however, during the labeling operation of the labeling machine, the defective label is prone to problems such as missing or falling off, which will cause the defective electrode piece unit to be wound to form an electrode assembly, thereby increasing the defective rate of the produced battery cells.

[0099] Based on the above considerations, in order to solve the problem of missing or falling labels when labeling defective pole piece units, a method for removing defective pole pieces is designed. When the pole piece strip is subjected to defect detection, defective labels can be affixed to the pole piece units distributed on the pole piece strip to identify the defective pole piece units. At the same time, the pole ears of the pole piece units can be cut to form structural defect marks. The defective pole piece units are identified by detecting the defective marks, and it is determined whether the defective pole piece units are wound separately. If they are not wound separately, it is a case of missing or falling labels for the defective labels. Thus, the electrode assemblies formed by the defective pole piece units are removed to avoid the situation where the defective labels are missed or fallen, and the electrode assemblies formed by the defective pole piece units are wound and assembled into battery cells, which leads to an increase in the defective rate of battery cells.

[0100] Figure 1 This is a flow chart of a method for rejecting bad electrode pieces according to an embodiment of the present application; Figure 3 This is a schematic diagram of the structure of the pole piece unit 100 provided in the embodiment of the present application. Figure 1 and Figure 3 The present application provides a method for rejecting bad electrode pieces, comprising the following steps:

[0101] Step S100, performing defect detection on a pole piece strip 10 having a plurality of continuously distributed pole piece units 100;

[0102] Step S200: based on the detection of the defect of the pole piece unit 100, a defect label 112 is attached to the defective pole piece unit 100, and at least one pole ear 110 of one of the pole piece units 100 is cut to form a structural defect mark 111;

[0103] Step S300, performing defect label 112 detection on the electrode unit 100 in the process of being wound into an electrode assembly;

[0104] Step S400, based on detecting that a defective label 112 exists in the electrode unit 100, the electrode unit 100 with the defective label 112 is wound separately;

[0105] Step S500, performing a structural defect mark 111 detection on the pole ear 110 of the pole piece unit 100 in the process of being wound into an electrode assembly;

[0106] Step S600, based on detecting that the pole lug 110 has a structural defect mark 111, identifying the pole piece unit 100 with a defect;

[0107] Step S700: determine whether the defective pole piece unit 100 is wound separately. If not, the electrode assembly formed by winding the defective pole piece unit 100 is discarded.

[0108] The electrode strip 10 may be a strip for forming a cathode electrode or an anode electrode. The electrode unit 100 refers to a section of the electrode strip 10 that can be wound to form an electrode assembly. It should be understood that the electrode strip 10 may be divided into a plurality of electrode units 100.

[0109] It can be understood that in step S100, the defect detection of the pole piece strip 10 can be performed by visual inspection; by visually inspecting the pole piece unit 100, it is determined whether the current pole piece unit 100 has defects.

[0110] In step S200, the defect label 112 may be a marking structure attached to the electrode unit 100 by a labeling device; illustratively, the marking structure may be a yellow adhesive label.

[0111] At the same time, in step S200, at least one pole ear 110 of one of the pole piece units 100 is cut to form a structural defect mark 111; optionally, at least one pole ear 110 of the defective pole piece unit 100 can be cut to form a structural defect mark 111; or, the pole ear 110 of the next pole piece unit 100 of the defective pole piece unit 100 can be cut to form a structural defect mark 111.

[0112] The operation of cutting the tab 110 to form the structural defect mark 111 can be performed by setting a cutting station and cutting through a cutting device; or, the operation of cutting the tab 110 to form the structural defect mark 111 can be performed simultaneously during the process of die-cutting the tab 110 .

[0113] Optionally, any part of the tab 110 may be cut to form a structural defect mark 111; meanwhile, the cut structural defect mark 111 may be in any shape, such as a hole shape, a groove shape, etc. The structural defect mark 111 may be composed of a hole structure or a groove structure; or, the structural defect mark 111 may be formed by a combination of multiple hole structures or multiple groove structures.

[0114] In step S300, the method of detecting the defect label 112 of the electrode unit 100 in the process of being wound into an electrode assembly can be performed by visual detection or sensor detection. Taking sensor detection as an example, the electrode unit 100 in the process of being wound into an electrode assembly is sensed to see whether there is a defect label 112. If a defect label 112 is present, the electrode unit 100 with the defect label 112 is defective.

[0115] In step S400, the pole piece unit 100 with the defect label 112 is wound separately; it can be understood that the defect label 112 is affixed to the pole piece unit 100 to mark the defect, thereby achieving the purpose of removing the defective pole piece unit 100, preventing it from being wound to form an electrode assembly, and then further assembled to form a battery cell, thereby reducing the defective rate of the battery cell.

[0116] In step S500, the structure defect mark 111 of the pole lug 110 of the pole piece unit 100 in the process of being wound into an electrode assembly can be detected by visual inspection; by visually inspecting the pole lug 110, it is determined whether the current pole lug 110 has the structure defect mark 111.

[0117] It should be understood that when the pole piece material strip 10 is subjected to defect detection, the pole piece material strip 10 will be unwound, so that the pole piece units 100 in the unwinding process can be detected in sequence. At the same time, the pole piece material strip 10 that has completed the detection will be rewound, so that during the unwinding process, the pole piece unit 100 located in the outermost layer will be rewound and wound into the innermost layer, and during the unwinding process, the pole piece unit 100 located in the innermost layer will be rewound and wound in the outermost layer.

[0118] In step S600, based on detecting the presence of a structural defect mark 111 on the pole lug 110, a defective pole piece unit 100 is identified; it is understandable that the structural defect mark 111 can be defined; illustratively, the pole piece unit 100 to which the pole lug 110 where the structural defect mark 111 is located belongs can be defined as a defective pole piece unit 100, or the next pole piece unit 100 of the pole piece unit 100 to which the pole lug 110 where the structural defect mark 111 is located can be defined as a defective pole piece unit 100, etc.

[0119] In step S700, the defective electrode unit 100 identified by detecting the structural defect mark 111 in step S600 is judged whether it is wound separately. If the electrode unit 100 is wound separately, it means that the defect label 112 is successfully attached, and after the defect label 112 is detected, the electrode unit 100 is wound separately to be rejected.

[0120] If the electrode unit 100 is not wound separately, it means that the defective label 112 is not successfully attached, or it falls off after being attached, so that the defective electrode unit 100 is not detected by the defective label 112, and then the defective electrode unit 100 is wound to form an electrode assembly. Therefore, in step S700, when the structural defect mark 111 is detected and it is determined that the defective electrode unit 100 marked by the structural defect mark 111 is not wound separately, it means that the label is missed or dropped; at this time, the electrode assembly formed by the defective electrode unit 100 can be discarded to prevent it from being further assembled to form a battery cell.

[0121] The method for rejecting defective pole pieces provided in the embodiment of the present application, after detecting that a pole piece unit 100 has a defect, forms a structural defect mark 111 by attaching a defect label 112 to the defective pole piece unit 100 and cutting at least one pole ear 110 of one of the pole piece units 100; thus, in the process of identifying the defective pole piece unit 100 by detecting the defective label 112 and winding it separately, if the defective label 112 falls off or is missed, the defective pole piece unit 100 will not be wound separately but will be wound to form an electrode assembly; at this time, the defective pole piece unit 100 is identified by detecting the structural defect mark 111 and it is determined whether the defective pole piece unit 100 is wound separately. If it is wound separately, it means that the defective label 112 is attached normally. If it is not wound separately, it means that the defective label 112 falls off or is missed, and the electrode assembly formed by winding the defective pole piece unit 100 is rejected to reduce the defective rate of the battery cells finally produced.

[0122] Please refer to Figure 1 and Figure 3 In some embodiments, the specific steps of cutting at least one pole ear 110 of one pole piece unit 100 and forming a structural defect mark 111 include:

[0123] At least one pole ear 110 of the defective pole piece unit 100 is cut to form a structural defect mark 111 .

[0124] It can be understood that the defective pole piece unit 100 is cut to form a structural defect mark 111, thereby, the pole piece unit 100 to which the pole ear 110 with the structural defect mark 111 belongs is defective; in this way, the defective pole piece unit 100 can be quickly determined.

[0125] Optionally, one of the pole ears 110 of the defective pole piece unit 100 may be cut to form a structural defect mark 111, for example, the first pole ear 110 (referring to the first pole ear 110 located in the unwinding direction during the inspection of the pole piece strip 10), the last pole ear 110 or any pole ear 110 of the defective pole piece unit 100 may be cut to form a mark; or, two or more pole ears 110 of the defective pole piece unit 100 may be cut to form a structural defect mark 111.

[0126] Please refer to Figure 1 and Figure 3 In some embodiments, the specific steps of identifying a defective pole piece unit 100 include:

[0127] After identifying that the pole tab 110 has a structural defect mark 111 , it is determined that the pole piece unit 100 where the pole tab 110 is located is a defective pole piece unit 100 .

[0128] It can be understood that since the structural defect mark 111 is formed on the pole ear 110 of the defective pole piece unit 100, after identifying that the pole ear 110 has the structural defect mark 111, it can be determined that the pole piece unit 100 where the pole ear 110 is located is a defective pole piece unit 100, so that the pole piece unit 100 can be subsequently discarded.

[0129] Please refer to Figure 1 and Figure 3 In some embodiments, the specific steps of cutting at least one pole ear 110 of one pole piece unit 100 and forming a structural defect mark 111 include:

[0130] At least one pole ear 110 of the next pole piece unit 100 distributed in the defective pole piece unit 100 is cut to form a structural defect mark 111.

[0131] It can be understood that the next pole piece unit 100 distributed in the defective pole piece unit 100 is cut to form a structural defect mark 111. Therefore, when a structural defect mark 111 is detected on the pole ear 110 of a section of pole piece unit 100, it can be determined that the next pole piece unit 100 of the pole piece unit 100 has a defect.

[0132] Exemplarily, during the inspection of the electrode strip 10, the electrode strip 10 in the form of a winding body is unwound and then rewound at the next location; when it is detected that one of the electrode units 100 has a defect, the pole ear 110 of the next pole unit 100 (that is, a pole unit 100 upstream in the unwinding direction) of the defective pole unit 100 can be cut to form a structural defect mark 111. It should be understood that after the electrode strip 10 is inspected and rewound at the next location, the wound body that has been inspected is used to wind to form an electrode assembly. At this time, in the winding direction of winding to form an electrode assembly, the pole unit 100 to which the pole ear 110 with the structural defect mark 111 belongs is located downstream of the defective pole unit 100; after the structural defect mark 111 is identified, a pole unit 100 upstream of the pole unit 100 to which the pole ear 110 with the structural defect mark 111 belongs should be rewound separately.

[0133] Please refer to Figure 1 and Figure 3 In some embodiments, the specific steps of identifying a defective pole piece unit 100 include:

[0134] After the structural defect mark 111 is identified, it is determined that the next pole piece unit 100 of the pole piece unit 100 where the pole ear 110 is located is a defective pole piece unit 100 .

[0135] With such arrangement, during the process of winding into an electrode assembly, after identifying that the pole tab 110 has a structural defect mark 111 , it can be determined that the next pole piece unit 100 of the pole tab 110 having the structural defect mark 111 is defective.

[0136] Please refer to Figure 1 and Figure 3 In some embodiments, the defect detection of the pole piece strip 10 having a plurality of continuously distributed pole piece units 100 further includes:

[0137] The pole piece strip 10 is die-cut to form the pole lug 110 , and at the same time, the last pole lug 110 on the corresponding pole piece unit 100 can be cut to form a structural defect mark 111 .

[0138] It is understandable that during defect detection of the pole piece strip 10 having a plurality of continuously distributed pole piece units 100 , the pole piece strip 10 is die-cut to cut out the pole lugs 110 and form a plurality of distributed pole piece units 100 .

[0139] With such an arrangement, the pole ear 110 can be cut to form a structural defect mark 111 simultaneously during the die-cutting process of the pole piece material strip 10, which can effectively reduce the process flow; at the same time, cutting the structural defect mark 111 on the last pole ear 110 on the pole piece unit 100 can facilitate the observation of the structural defect mark 111.

[0140] Please refer to Figure 2 and Figure 3 In some embodiments, the structure defect mark 111 detection of the pole ear 110 of the pole piece unit 100 in the process of being wound into an electrode assembly includes the following steps:

[0141] Step S301, obtaining an image of the electrode tab 110 to be tested,

[0142] Step S302, input the image of the pole lug 110 to be tested into the image classification model to obtain the detection result of the image of the pole lug 110 to be tested, wherein the image classification model is trained using a sample set, and the sample set includes the image of the pole lug 110 marked with multiple classification labels; the multiple classification labels include defect type and defect orientation; the detection result is at least one of the multiple classification labels.

[0143] In step S301 , the image of the electrode tab 110 to be tested may be an image obtained by photographing the electrode tab 110 using an imaging device.

[0144] In the above, the image classification model is obtained by pre-training the initial network model with a sample set, and the sample set includes a plurality of tab 110 images, and these tab 110 images are annotated with classification labels, and each tab 110 image is annotated with a classification label.

[0145] Exemplarily, the multiple classification labels may include defect type, defect orientation, etc. The image classification model may detect the input image of the electrode tab 110 to be tested to obtain a detection result. The detection result may be at least one of the defect type and defect orientation.

[0146] With such an arrangement, the defect type and defect orientation information can be determined based on the image of the pole ear 110 to be tested, so that the defective pole piece unit 100 can be individually wound and removed later. At the same time, manual tracing can also be performed based on the defect type and defect orientation information.

[0147] Please refer to Figures 3 to 5 In some embodiments, in the distribution direction X of the pole piece unit 100 , the structural defect mark 111 is located at at least one side corner of the pole ear 110 .

[0148] It can be understood that the pole ear 110 is generally a rectangular structure or a trapezoidal structure, and one end of the pole ear 110 is connected to the pole piece unit 100 . Therefore, the two angular structures formed by the other end of the pole ear 110 facing away from the pole piece unit 100 are the apex angles of the pole ear 110 .

[0149] The structural defect mark 111 is opened at the top corner of the pole ear 110, that is, the pole ear 110 is cut from the side facing away from the pole piece unit 100 to the side where the pole ear 110 intersects with the pole piece unit 100. The slot structure formed by cutting off the top corner part here is the structural defect mark 111.

[0150] Optionally, the structural defect mark 111 may be cut at one of the top corners of the tab 110; or, the structural defect mark 111 may be cut at both top corners of the tab 110. At the same time, the top corners of the tab 110 may be cut to form an arc groove, or may be cut to form a rectangular groove or other configurations.

[0151] In some embodiments, the cutting position of the structural defect mark 111 can be defined. For example, when the defect label is formed on the upstream side of the tab 110 in the unwinding direction, the defect position can be considered to be upstream of the tab 110 with the structural defect mark 111; when the defect label is formed on the downstream side of the tab 110 in the unwinding direction, the defect position can be considered to be downstream of the tab 110 with the structural defect mark 111.

[0152] Please refer to Figures 4 to 6In some embodiments, in the distribution direction X of the pole piece unit 100, the structural defect mark 111 forms a first straight edge 111a, and in the distribution direction X perpendicular to the pole piece unit 100, the structural defect mark 111 forms a second straight edge 111b; wherein an angle α is formed between the first straight edge 111a and the second straight edge 111b, 60°≤α≤120°.

[0153] It can be understood that the first straight edge 111 a and the second straight edge 111 b intersect, and thus a portion of the electrode tab 110 can be removed by cutting to form the first straight edge 111 a and the second straight edge 111 b to form the structural defect mark 111 .

[0154] The angle α formed between the first straight edge 111a and the second straight edge 111b is limited to be greater than or equal to 60° and less than or equal to 120°, so as to reduce the probability of the tab 110 being folded when the angle α is too small or too large.

[0155] Please refer to Figure 6 In some embodiments, a chamfer 111c is formed at a connection point between the first straight edge 111a and the second straight edge 111b.

[0156] It can be understood that by cutting between the first straight edge 111a and the second straight edge 111b to form a chamfer 111c, the cutting between the first straight edge 111a and the second straight edge 111b is smoother. Compared with the situation where burrs or waste materials are easily generated when the first straight edge 111a and the second straight edge 111b are cut to form a right angle, an acute angle, or an obtuse angle, the method of cutting to form the chamfer 111c can effectively reduce the probability of waste materials or burrs being generated between the first straight edge 111a and the second straight edge 111b.

[0157] Please refer to Figure 7 In some embodiments, in the distribution direction X perpendicular to the pole piece unit 100 , the structural defect mark 111 is located at one end of the pole ear 110 facing away from the pole piece unit 100 .

[0158] In this embodiment, the structural defect mark 111 can also be formed at the end of the pole ear 110 facing away from the pole piece unit 100; the structural defect mark 111 can be cut to form a variety of slot structures such as rectangular slots and arc slots, but is not limited to. In some embodiments, the structural defect mark 111 can also be defined, for example, the structural defect mark 111 of different configurations formed by cutting corresponds to the type information of the defect, the location information of the defect in the pole piece unit 100, etc.

[0159] Please refer to Figure 7In some embodiments, the structural defect marker 111 includes a first marking hole 1111 and a second marking hole 1112 that are connected to each other. The first marking hole 1111 is connected to the outside in a distribution direction X perpendicular to the pole piece unit 100; the second marking hole 1112 is an arc-shaped hole.

[0160] Optionally, the first identification hole 1111 may be, but not limited to, a polygonal hole such as an arc hole, a rectangular hole, etc. The second identification hole 1112 is an arc hole, and illustratively, the second identification hole 1112 may be, but not limited to, a semicircular hole, an arc hole, etc.

[0161] By configuring in this way, the probability of generating residual material in the second identification hole 1112 can be effectively reduced by cutting the inner second identification hole 1112 to form an arc-shaped hole.

[0162] Please refer to Figure 6 or Figure 7 In some embodiments, the structural defect mark 111 is an arc-shaped structural mark.

[0163] Optionally, the structural defect mark 111 in the shape of an arc structure mark can be formed at at least one vertex corner of the pole ear 110 , or the structural defect mark 111 in the shape of an arc structure mark can also be formed on the side of the pole ear 110 facing away from the pole piece unit 100 .

[0164] In this way, by cutting the structural defect mark 111 to form an arc-shaped structural mark, the probability of forming waste material can be effectively reduced.

[0165] Please refer to Figure 4 and Figure 5 In the distribution direction X of the pole piece unit 100, the pole ear 110 has a width D, and the structural defect mark 111 has a width d, 1mm≤d≤3D / 4.

[0166] In this way, the width of the structural defect mark 111 is limited to be greater than or equal to 1 mm (hereinafter expressed in mm) to reduce the difficulty of cutting and the probability that the structural defect mark 111 is too narrow and difficult to identify; at the same time, the width of the structural defect mark 111 is limited to be less than or equal to 3D / 4, so that the width of the structural defect mark 111 does not exceed three quarters of the width of the pole ear 110, so as to reduce the probability of the pole ear 110 being folded.

[0167] Please refer to Figure 4 and Figure 5 In some embodiments, in the distribution direction X perpendicular to the pole piece unit 100 , the pole ear 110 has a height H, the structural defect mark 111 has a height h, and 1mm≤h≤H / 2.

[0168] In this way, the height of the structural defect mark 111 is limited to be greater than or equal to 1 mm, so as to reduce the difficulty of cutting and reduce the probability that the structural defect mark 111 is too small to be difficult to identify; at the same time, the height of the structural defect mark 111 is limited to be less than or equal to H / 2, so that the height of the structural defect mark 111 does not exceed half of the height of the pole ear 110, so as to reduce the probability of the pole ear 110 being folded.

[0169] Please refer to Figure 8 In some embodiments, the structural defect mark 111 is located in the middle of the tab 110 .

[0170] Optionally, one or more structural defect marks 111 may be provided in the middle of the tab 110. The structural defect marks 111 provided in the middle of the tab 110 may be, but are not limited to, circular hole marks, rectangular hole marks, bar hole marks, wavy hole marks, and other configuration marks; marks of different configurations may be used, or two or more marks may be combined to define different combinations of structural defect marks 111, so that the location of the existing defect, the type of defect, and other information may be determined by identifying the structural defect marks 111.

[0171] Below, the method for removing bad electrode pieces according to the embodiment of the present application will be described in detail based on specific implementation methods.

[0172] In this embodiment, the method for removing bad electrode pieces includes the following steps:

[0173] Step S10, performing defect detection on a pole piece strip 10 having a plurality of continuously distributed pole piece units 100;

[0174] Step S20: based on the detection of the defect in the pole piece unit 100, a defect label 112 is attached to the defective pole piece unit 100, and the last pole ear 110 of the defective pole piece unit 100 is cut to form a structural defect mark 111;

[0175] Step S30, performing defect label 112 detection on the electrode unit 100 in the process of being wound into an electrode assembly;

[0176] Step S40, based on detecting that there is a defective label 112 in the pole piece unit 100, winding the pole piece unit 100 with the defective label 112 attached separately;

[0177] Step S50, performing a structural defect mark 111 detection on the pole ear 110 of the pole piece unit 100 in the process of being wound into an electrode assembly;

[0178] Step S60, identifying a structural defect mark 111;

[0179] Step S70, identifying the defective pole piece unit 100 according to the structural defect mark 111; that is, the pole piece unit 100 where the pole ear 110 with the structural defect mark 111 is located is the defective pole piece unit 100;

[0180] Step S80 , determining whether the defective pole piece unit 100 is wound separately; if not, discarding the electrode assembly formed by winding the defective pole piece unit 100 .

[0181] If it is not wound separately, it means that a defective label 112 is missed during the process of affixing in step S20, or a label is lost in a subsequent step.

[0182] Please refer to Figure 3 and Fig. 9 In the second aspect, the embodiment of the present application further provides a die-cutting device 1000, including a winding unit 1100, a die-cutting unit 1200, a defect detection unit 1300, a marking unit 1400 and a second control unit (not shown in the figure).

[0183] The winding unit 1100 is used to pull the pole piece strip 10 along a preset direction S; the die-cutting unit 1200 is used to die-cut the pole ear 110 on the pole piece strip 10 to produce a plurality of continuously distributed pole piece units 100; the die-cutting unit 1200 is also used to cut and form a structural defect mark 111 on the pole ear 110.

[0184] The defect detection unit 1300 is used to perform connection defect detection on the pole piece unit 100 and feed back to the die-cutting unit 1200 for cutting to form a structural defect mark 111; the marking unit 1400 is used to attach a defect label 112 to the pole piece unit 100 with defects.

[0185] The second control unit is communicatively connected with the winding unit 1100, the die-cutting unit 1200, the defect detection unit 1300 and the marking unit 1400; when the defect detection unit 1300 detects that the pole piece unit 100 has a defect, the marking unit 1400 affixes a defect label 112 to the defective pole piece unit 100, and at the same time the die-cutting unit 1200 cuts the pole ear 110 to form a structural defect mark 111.

[0186] A missing label sensor may be arranged behind the marking unit 1400 to determine whether a missing label occurs.

[0187] After the die-cutting device 1000 is used to die-cut and cut the pole piece unit 100 on the pole piece strip 10 to form the structural defect mark 111, the following steps may also be included:

[0188] The electrode strip 10 that is in the process of being wound to form an electrode assembly is inspected for defective labels 112. Based on the detection of the presence of defective labels 112 on the electrode units 100 distributed on the electrode strip 10, it can be determined that the electrode unit 100 with the defective label 112 is a defective electrode unit 100, and the electrode unit 100 is wound separately to be removed.

[0189] Then continue to detect the structural defect mark 111 of the pole piece strip 10. Based on the detection of the structural defect mark 111 on the pole ear 110 of the pole piece unit 100 distributed on the pole piece strip 10, take the structural defect mark 111 formed on the pole ear 110 of the defective pole piece unit 100 as an example, identify whether the defective pole piece unit 100 is wound separately. If it is not wound separately, the electrode assembly formed by the defective pole piece unit 100 is discarded; thereby reducing the probability of missing or falling off the label during the process of attaching the defective label 112, resulting in the defective pole piece unit 100 being wound to form an electrode assembly and increasing the probability of defective rate of the electrode assembly.

[0190] The die-cutting device 1000 provided in the embodiment of the present application can utilize the die-cutting unit 1200 to die-cut the pole ear 110 on the pole piece strip 10. According to the feedback from the defect detection unit 1300, the die-cutting unit 1200 can also simultaneously cut the pole ear 110 to form a structural defect mark 111, and the marking unit 1400 can also attach a defect label 112 to the defective pole piece unit 100, thereby facilitating the identification of defects and the removal of bad products in subsequent winding operations.

[0191] Please refer to Figure 3 and Fig.10 In the third aspect, the embodiment of the present application also provides a winding device 2000, including an anode unwinding unit 2100, a cathode unwinding unit 2200, an isolation film unwinding unit (not shown in the figure), a winding needle 2300, a label detection unit 2400 and a third control unit (not shown in the figure).

[0192] The anode unwinding unit 2100 is used to unwind the anode electrode sheet, the cathode unwinding unit 2200 is used to unwind the cathode electrode sheet, and the separator unwinding unit is used to unwind the separator; the winding needle 2300 is used to separate the anode electrode sheet and the cathode electrode sheet with the separator and wind them to prepare the electrode assembly;

[0193] The label detection unit 2400 is used to detect defective labels on the anode electrode sheet when the winding needle 2300 is winding the anode electrode sheet, and / or, to detect defective labels on the cathode electrode sheet when the winding needle 2300 is winding the cathode electrode sheet; wherein the defective labels include a structural defect mark 111 cut and formed on the anode electrode sheet's tab 110 and / or the cathode electrode sheet's tab 110 and a defective label 112 attached to the anode electrode sheet and / or the cathode electrode sheet;

[0194] The third control unit is in communication connection with the anode unwinding unit 2100 , the cathode unwinding unit 2200 , the separator unwinding unit, the winding needle 2300 , and the identification detection unit.

[0195] Among them, the label detection unit 2400 may include a sensor 2410 for detecting defective labels 112, and the label detection unit 2400 may also include a visual sensing device 2420 for detecting the structural defect mark 111 on the pole ear 110. The image of the pole ear 110 is obtained by the visual sensing device 2420 for analysis to identify the structural defect mark 111.

[0196] In the case where the previously defective electrode unit 100 (which may be the electrode unit 100 of the cathode electrode or the electrode unit 100 of the anode electrode, and the cathode electrode is used as an example below) is marked by cutting to form a structural defect mark 111, the label detection unit 2400 can be used to detect the structural defect mark 111. When the structural defect mark 111 is formed on the electrode ear 110 of the electrode unit 100 of the defective cathode electrode, the label detection unit 2400 can feedback an electrical signal and stop the anode unwinding unit 2100 and the isolation film unwinding unit from unwinding, and the anode electrode and the isolation film are in a state of being disconnected from the winding needle 2300; while the cathode unwinding unit 2200 continues to unwind the cathode electrode, and the winding needle 2300 winds up one electrode unit 100 of the cathode electrode alone, so that the defective electrode unit 100 is wound up alone to be rejected.

[0197] The winding device 2000 provided in the embodiment of the present application utilizes the label detection unit 2400 to identify defective labels so as to separately wind up the defective cathode electrode sheet and / or anode electrode sheet.

[0198] Please refer to Fig. 9 and Fig.10 In a fourth aspect, an embodiment of the present application further provides a battery production system (not shown in the figure), comprising the die-cutting device 1000 as described above and / or the winding device 2000 as described above.

[0199] The battery production system provided in the embodiment of the present application, based on the die-cutting device 1000 and / or the winding device 2000 as described above, has a lower defective rate of products produced by the battery production system.

[0200] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for removing bad electrode pieces, characterized in that: include: Defect detection is performed on a pole piece strip having a plurality of continuously distributed pole piece units; Based on the detection of the defect in the pole piece unit, a defect label is attached to the defective pole piece unit, and at least one pole ear of one of the pole piece units is cut to form a structural defect mark; Conduct defect label detection on the electrode unit in the process of being wound into an electrode assembly; Based on the detection of the defective label on the pole piece unit, the pole piece unit with the defective label is individually wound; Perform structural defect identification detection on the pole lugs of the pole piece units in the process of being wound into an electrode assembly; Based on detecting that the pole lug has the structural defect mark, identifying the pole piece unit with the defect; It is determined whether the defective pole piece unit has been wound separately. If it has not been wound separately, it has been wound to form an electrode assembly, and the electrode assembly formed by winding the defective pole piece unit is discarded.

2. The method for removing bad electrode pieces according to claim 1, characterized in that: The specific steps of cutting at least one pole ear of one pole piece unit and forming a structural defect mark include: At least one pole ear of a defective pole piece unit is cut to form a structural defect mark.

3. The method for removing bad electrode pieces according to claim 2, characterized in that: The specific steps of identifying the defective pole piece unit based on detecting the presence of the structural defect mark on the pole lug include: After identifying that the pole lug has the structural defect mark, it is determined that the pole piece unit where the pole lug is located is the defective pole piece unit.

4. The method for removing bad electrode pieces according to claim 1, characterized in that: The specific steps of cutting at least one pole ear of one pole piece unit and forming a structural defect mark include: At least one pole ear of the next pole piece unit distributed in the pole piece unit with defects is cut to form a structural defect mark.

5. The method for removing bad electrode pieces according to claim 4, characterized in that: The specific steps of identifying the defective pole piece unit based on detecting the presence of the structural defect mark on the pole lug include: After the structural defect mark is identified, the next pole piece unit of the pole piece unit where the pole lug is located is determined to be the defective pole piece unit.

6. The method for removing bad electrode pieces according to any one of claims 2 to 5, characterized in that: In the defect detection of a pole piece strip having a plurality of continuously distributed pole piece units, it also includes: The pole piece strip is die-cut to form pole ears, and at the same time, the last pole ear on the corresponding pole piece unit is cut to form a structural defect mark.

7. The method for removing bad electrode pieces according to claim 1, characterized in that: The step of detecting structural defects on the pole lugs of the pole piece units in the process of being wound into an electrode assembly also includes: Get the image of the tab to be tested. Inputting the image of the pole lug to be tested into an image classification model to obtain a detection result of the image of the pole lug to be tested, wherein the image classification model is trained using a sample set, and the sample set includes pole lug images marked with multiple classification labels; The multiple classification labels include defect type and defect orientation; The detection result is at least one of the multiple classification labels.

8. The method for removing bad electrode pieces according to claim 1, characterized in that: In the distribution direction of the pole piece units, the structural defect mark is located at at least one side corner of the pole lug.

9. The method for removing bad electrode pieces according to claim 8, characterized in that: In the distribution direction of the pole piece unit, the structural defect mark forms a first straight edge, and in the distribution direction perpendicular to the pole piece unit, the structural defect mark forms a second straight edge; wherein an angle α is formed between the first straight edge and the second straight edge, 60°≤α≤120°.

10. The method for removing bad electrode pieces according to claim 9, characterized in that: A chamfer is formed at a connection between the first straight edge and the second straight edge.

11. The method for removing bad electrode pieces according to claim 1, characterized in that: In a distribution direction perpendicular to the pole piece unit, the structural defect mark is located at an end of the pole ear that is opposite to the pole piece unit.

12. The method for removing bad electrode pieces according to claim 11, characterized in that: The structural defect mark includes a first marking hole and a second marking hole that are connected to each other. The first marking hole is connected to the outside in a distribution direction perpendicular to the pole piece unit; the second marking hole is an arc-shaped hole.

13. The method for removing bad electrode pieces according to claim 8 or 11, characterized in that: The structural defect mark is an arc-shaped structural mark.

14. The method for rejecting bad electrode pieces according to any one of claims 8 to 11, characterized in that: In the distribution direction of the pole piece unit, the pole ear has a width D, the structural defect mark has a width d, and 1mm≤d≤3D / 4.

15. The method for rejecting bad electrode pieces according to any one of claims 8 to 11, characterized in that: In a distribution direction perpendicular to the pole piece unit, the pole ear has a height H, and the structural defect mark has a height h, 1mm≤h≤H / 2.

16. The method for removing bad electrode pieces according to claim 1, characterized in that: The structural defect mark is located in the middle of the pole lug.

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