Battery cell detection method, battery cell detection device and battery cell deviation correction method

Abstract

The invention relates to the technical field of batteries, and discloses a battery cell detection method, a battery cell detection device and a battery cell deviation rectifying method.The battery cell detection method comprises the steps that an end face image of a battery cell is obtained, two feature areas which are in one-to-one correspondence with tabs of two polarities are recognized, a datum point of the center of the end face is determined according to the end face image, and the datum point of the center of the end face is obtained; the two feature regions are respectively arranged on two sides of the reference point; rotating the end face image to enable the arrangement direction of the two characteristic areas and the reference line to form a set included angle, enabling the reference line to pass through the reference point, and initially adjusting the angle of the end face image to enable the two tabs with opposite polarities to be located in the middle position between the two forbidden areas theoretically; the two prohibited areas are not overlapped with the two prohibited areas under the condition that the alignment degree meets the requirement; and judging whether the two characteristic areas are overlapped with the two prohibited areas, if yes, judging that the battery cell is unqualified, preventing the battery cell with poor alignment from flowing out, and the two prohibited areas are located on the reference line and symmetrically distributed on the two sides of the reference point.

Description

[0001] This application is a divisional application. The application number of the original application is 202411478608.5 and the original application date is October 2024. On the 22nd, the original application was titled A battery cell detection method, a battery cell detection device and a battery cell deviation correction method ”, all the contents of the original application The contents are incorporated into this application by reference. Technical Field

[0002] The present invention relates to the technical field of batteries, and in particular to a battery cell detection method, a battery cell detection device and a battery cell deviation correction method. Background Art

[0003] In the production process of cylindrical batteries (such as top-flow cylindrical batteries), the positive and negative tabs are set on the same side of the battery cell. However, during the winding process of the battery cell, the tabs may deviate from the ideal position, resulting in the tab alignment not being within a reasonable range, which in turn leads to safety issues such as short circuit, excessive internal resistance, and poor appearance. However, it is difficult to effectively detect the tab alignment with traditional technical solutions. Summary of the invention

[0004] The invention discloses a battery cell detection method, a battery cell detection device and a battery cell deviation correction method, which are used for effectively detecting the alignment of tabs.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] In a first aspect, a method for detecting a battery cell is provided, wherein the end face of the battery cell is provided with pole ears with opposite polarities; the method comprises: obtaining an end face image of the battery cell, identifying two characteristic regions corresponding to the pole ears of two polarities one to one, and determining a reference point of the center of the end face according to the end face image, wherein the two characteristic regions are arranged on both sides of the reference point; rotating the end face image so that the arrangement direction of the two characteristic regions forms a set angle with a reference line, the set angle is between 85° and 95°, and the reference line passes through the reference point, and the angle of the end face image is firstly rotated. Perform preliminary adjustments so that theoretically the two pole ears with opposite polarities are centered between the two prohibited areas, and the two will not overlap with the two prohibited areas when the alignment meets the requirements; determine whether the two characteristic areas overlap with the two prohibited areas. If so, the battery cell is determined to be unqualified, wherein the two prohibited areas are located on the reference line and symmetrically distributed on both sides of the reference point. Each of the prohibited areas is a sector with the reference point as the center and the reference line as the axis of symmetry, and the circumferential angle corresponding to the prohibited area is between 5° and 20°. The area adjacent to the reference line is designated as a prohibited area. Once the two characteristic areas overlap with the prohibited area, it indicates that there is a risk of the two characteristic areas being too close and the alignment is poor. This part of the battery cell is regarded as a seriously defective product and is determined to be unqualified, effectively screening out seriously defective products and preventing them from flowing out.

[0007] In a second aspect, a battery cell detection device is provided, wherein the end face of the battery cell is provided with a pole ear with opposite polarity; the battery cell detection device comprises: an image acquisition unit and a processing unit; the image acquisition unit is used to acquire the end face image of the battery cell, identify two characteristic areas corresponding to the pole ears of two polarities one to one, and determine the reference point of the center of the end face according to the end face image, wherein the two characteristic areas are arranged on both sides of the reference point; the processing unit is used to adjust the end face image so that the arrangement direction of the two characteristic areas is at a set angle with a reference line, and the reference line passes through the reference point, and determines whether the two characteristic areas overlap with two prohibited areas. If so, the battery cell is determined to be unqualified, wherein the two prohibited areas are located on the reference line and symmetrically distributed on both sides of the reference point. Each prohibited area is a sector with the reference point as the center and the reference line as the axis of symmetry, and the circumferential angle corresponding to the prohibited area is between 5° and 20°; the set angle is between 85° and 95°.

[0008] The advantages of the battery cell detection device and the above-mentioned battery cell detection method over the prior art are the same, which will not be described in detail here.

[0009] In a third aspect, a cell correction method based on the above-mentioned cell detection method comprises: when the absolute value of the difference between the initial angle and the set angle is greater than 0, controlling the driving component to drive the cell to rotate the angle of the difference, and the rotation direction of the cell is the same as the rotation direction of the end face image, so as to perform preliminary correction on the cell, wherein the initial angle refers to the angle between the arrangement direction of the two feature areas before the end face image is rotated and the reference line; when the focus parts of the two feature areas are located on the same side of the reference point in the direction of the reference line, rotating the cell so that the focus parts of the two feature areas are equal in area or the corresponding circumferential angles are the same, so as to achieve the desired correction. The alignment deviation of the battery cell is dispersed to the two characteristic areas so that the position deviation of the two characteristic areas is minimized; or, when the focus parts of the two characteristic areas are located on different sides of the reference point in the direction of the reference line, the battery cell is rotated to make the areas of the characteristic areas in the four dangerous areas approach each other, thereby dispersing the alignment deviation of the battery cell to the two characteristic areas so that the position deviation of the two characteristic areas is minimized, thereby dispersing the alignment deviation of the battery cell to the two characteristic areas so that the position deviation of the two characteristic areas is minimized; wherein the focus part refers to a larger part of the overlapping part of each characteristic area with the dangerous areas on both sides. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1A schematic diagram of an end face image obtained in the battery cell detection method provided in an embodiment of the present application;

[0011] Figure 2 A schematic diagram of identifying a characteristic area S in the battery cell detection method provided in an embodiment of the present application;

[0012] Figure 3 A schematic diagram showing a rotated end face image in a battery cell detection method provided in an embodiment of the present application;

[0013] Figure 4 Express Figure 3 Schematic diagram of region division of the image shown;

[0014] Figure 5 express Figure 4 Position relationship diagram of the forbidden area D and the characteristic area S;

[0015] Figure 6 express Figure 4 Schematic diagram of the tangent position relationship of the characteristic area S;

[0016] Figure 7 A schematic diagram showing the positional relationship between the first midline and the second midline of the feature area S;

[0017] Figure 8 express Figure 4 Position relationship diagram of the ideal area T and the characteristic area S of the middle tab;

[0018] Fig. 9 express Figure 4 Position relationship diagram of the middle ear danger area G and the characteristic area S;

[0019] Fig.10 express Figure 3 A position relationship diagram of each characteristic area S and the corresponding virtual welding area W;

[0020] Fig.11 A flow chart showing an application scenario of the battery cell detection method and the battery cell deviation correction method provided in an embodiment of the present application;

[0021] Fig.12 express Fig.11 A schematic diagram of the structure of the image acquisition unit used in step S3;

[0022] Fig.13 express Fig.11 Schematic diagram of the structure of the image acquisition unit used in step S6. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] In order to have a clearer understanding of the battery cell detection method provided in the embodiment of the present application, its background is briefly introduced below. The battery cell of a cylindrical battery (such as a top-flow cylindrical battery) can be a wound battery cell, for example, by winding the positive electrode sheets and the negative electrode sheets that are alternately stacked in sequence to form a roughly cylindrical wound battery cell, wherein a diaphragm is provided between adjacent positive electrode sheets and negative electrode sheets for insulating the positive electrode sheets and the negative electrode sheets, and in order to form good insulation, the length of the diaphragm can be greater than the length of the positive electrode sheets and the negative electrode sheets.

[0025] refer to Figure 1 The end face 10 of the wound battery cell is provided with a pole ear P with opposite polarity, and the pole ear P may include a plurality of positive pole ears P1 connected to the positive electrode sheet (refer to Figure 1 ) and multiple negative electrode tabs P2 connected to the negative electrode plate, the positive electrode tab P1 and the negative electrode tab P2 are arranged on the same side of the battery cell; for example, the material of the positive electrode tab P1 can be copper, and the material of the negative electrode tab P2 can be aluminum, but not limited to this, the material of the positive electrode tab P1 and the negative electrode tab P2 can be adjusted as needed.

[0026] Before winding, the above multiple positive electrode tabs P1 (reference Figure 1 ) are sequentially arranged at intervals on the edge of the positive electrode sheet, and multiple negative electrode tabs P2 (reference Figure 1 ) are sequentially arranged at intervals on the edge of the negative electrode sheet. After the battery cell is wound and formed, the alignment of the multiple positive electrode tabs P1 corresponding to the positive electrode sheets from the inner layer to the outer layer should be within a reasonable range in theory, and the negative electrode tab P2 should also meet similar requirements. However, in the actual winding process, the inner positive electrode tab P1 and the outer positive electrode tab P1 are prone to misalignment, which in turn causes the positive electrode tab P1 to gradually shift, and the alignment does not meet the requirements, which may cause the distance between the positive electrode tab P1 and the negative electrode tab P2 to be too close, resulting in safety issues such as short circuit of the battery cell, excessive internal resistance and poor appearance.

[0027] In order to solve the above problems, the battery cell detection method provided in the embodiment of the present application includes: referring to Figure 1 , obtain the end face image of the battery cell, and then refer to Figure 2, identify two characteristic regions S corresponding to the two polarity tabs P one to one, such as the two characteristic regions S are the positive characteristic region S1 corresponding to the positive tab P1, and the negative characteristic region S2 corresponding to the negative tab P2, and determine the reference point O at the center of the end face according to the end face image, wherein the two characteristic regions S are arranged on both sides of the reference point O, and the reference point O is used as a reference point in subsequent steps; reference Figure 3 , rotate the end face image so that the arrangement direction of the two characteristic areas S is at a set angle b with the reference line L1, and the reference line L1 passes through the reference point O. In this step, the angle of the end face image is preliminarily adjusted so that theoretically the positive electrode tab P1 and the negative electrode tab P2 are centered between the two prohibited areas D, and the two will not overlap with the two prohibited areas D when the alignment meets the requirements; next, determine whether the two characteristic areas S overlap with the two prohibited areas D. If so, the battery cell is determined to be unqualified, wherein the two prohibited areas D are located on the reference line L1 and are symmetrically distributed on both sides of the reference point O, the prohibited area D1 is located on the left side of the reference point O, and the prohibited area D2 is located on the right side of the reference point O. The area adjacent to the reference line L1 is designated as a prohibited area D. Once the positive characteristic area S1 overlaps with at least one of the prohibited area D1 and the prohibited area D2, or the negative characteristic area S2 overlaps with at least one of the prohibited area D1 and the prohibited area D2, it means that there is a risk that the positive characteristic area S1 and the negative characteristic area S2 are too close to each other. These cells are regarded as seriously defective products and are judged as unqualified, effectively screening out seriously defective products and preventing them from flowing out. Among them, after performing the above-mentioned rotation of the end face image and preliminarily adjusting the angle of the end face image, the positive characteristic area S1 can be located above the reference L1, and the negative characteristic area S2 can be located below the reference L1, and an additional detection step can be added: by judging whether the positive characteristic area S1 and the negative characteristic area S2 meet the above rules according to the colors of the two characteristic areas S, if not, the cell is judged to be unqualified.

[0028] Combination Figure 4 and Figure 5 In a specific embodiment, each forbidden area D is a sector with the reference point O as the center and the reference line L1 as the axis of symmetry. Figure 5In the figure, both are fan-shaped and symmetrical about the reference line L1. Theoretically, after the battery cell is wound, multiple positive pole tabs P1 form a fan-shaped area with the reference point O as the center, and multiple negative pole tabs P2 also form a fan-shaped area with the reference point O as the center. Therefore, the two characteristic areas S are theoretically fan-shaped; the prohibited area D is also fan-shaped and is set in the above manner. The two prohibited areas D can theoretically be located exactly in the middle of the positive characteristic area S1 and the negative characteristic area S2, and are adapted to the fan-shaped shape of the characteristic area S, which has a relatively balanced warning effect on the two characteristic areas S. The so-called "theoretically" refers to the situation where the positive pole tab P1 and the negative pole tab P2 do not deviate during the winding process. The circumferential angle corresponding to each prohibited area D can be between 5° and 20°, for example, it can be 5°, 8°, 11°, 15°, 18° and 20°, etc. If the circumferential angle corresponding to the prohibited area D is too large, it will cause the characteristic area S to enter the prohibited area D too easily, causing the battery cells that actually meet the performance requirements to be eliminated. If the circumferential angle corresponding to the prohibited area D is too small, the distance between the two characteristic areas S will be close enough, and the positive electrode tab P1 and the negative electrode tab P2 will be prone to short circuit, but the characteristic area S still will not enter the prohibited area D, causing defective products to flow out.

[0029] In a specific embodiment, the angle b is set between 85° and 95°, for example, it can be 85°, 90° and 95°, so that the arrangement direction of the two feature areas S is close to perpendicular to the reference line L1 or completely perpendicular to the reference line L1. Therefore, each feature area S is theoretically located in the center of the two prohibited areas D to avoid one side of the feature area S being too inclined toward the reference line L1 and too easily entering the prohibited area D.

[0030] In a specific embodiment, the arrangement direction of the two feature regions S refers to the direction of the line connecting the centroids K of the two feature regions S. For example, Figure 3 The direction of the line L2 connecting the centroid K1 of the positive electrode characteristic region S1 and the centroid K2 of the negative electrode characteristic region S2 is used as the arrangement direction of the positive electrode characteristic region S1 and the negative electrode characteristic region S2.

[0031] refer to Figure 2When identifying two characteristic regions S, due to the redundancy of the length of the diaphragm between the positive electrode sheet and the negative electrode sheet, the redundant part covers the end face 10 of the battery cell, so it is difficult to distinguish the boundary between the tab P and the diaphragm. If the line connecting the geometric centers of the inscribed rectangle of the characteristic region S is selected as the arrangement direction of the two characteristic regions S, it is difficult to determine the position of the inscribed rectangle, but when determining the centroid K, there are equal probability offset errors on different edges of the characteristic region S, which can offset each other. In theory, the position offset of the centroid K is small. Therefore, the position of the centroid K can be determined more accurately. The line connecting the two centroids K can more accurately reflect the arrangement direction of the two characteristic regions S, and the characteristic region S is not easy to tilt to one side.

[0032] In a specific embodiment, determining the reference point O according to the end face image specifically includes: identifying the contour M of the end face 10, and using the center of the circumscribed circle or the center of the inscribed circle of the contour M of the end face 10 as the reference point O. During the winding process of the battery cell, due to various errors, the contour M of the final end face 10 is not a standard circle. Therefore, using the center of the circumscribed circle or the center of the inscribed circle of the contour M of the end face 10 as the reference point O can more accurately reflect the center position of the end face 10.

[0033] In a specific embodiment, each feature region S has two tangent lines passing through the reference point O, for example, Figure 6 , the positive characteristic region S1 has tangent L6 and tangent L7 passing through the reference point O, and the negative characteristic region S2 has tangent L9 and tangent L10 passing through the reference point O; the above method also includes: judging whether the angle between each tangent and the reference line L1 is within the first threshold range, if not, judging that the battery cell is unqualified, if the angle between the tangent L6 and the reference line L1 is too small, or the angle between the tangent L7 and the reference line L1 is too large, it indicates that the positive characteristic region S1 is too inclined to one side of the tangent L6, and the judgment method of the tangent L9 and the tangent L10 is similar.

[0034] Determine whether the angle between adjacent tangents of two characteristic regions S is within the second threshold range. If not, the battery cell is determined to be unqualified. For example, if the angle between the tangent L7 of the positive characteristic region S1 and the tangent L9 of the negative characteristic region S2 is too small, it indicates that the positive characteristic region S1 and the negative characteristic region S2 are too close, and a short circuit between the positive electrode tab P1 and the negative electrode tab P2 is likely to occur. Therefore, the battery cell is determined to be unqualified. Determine whether the angle between the two tangents of each characteristic region S is within the third threshold range. If not, the battery cell is determined to be unqualified. For example, if the angle between the tangent L6 and the tangent L7 of the positive characteristic region S1 is too large, it indicates that the misalignment between the positive electrode plates of different layers of the positive characteristic region S1 may be too large. If the angle between the tangent L6 and the tangent L7 is too small, it indicates that the area of ​​the positive characteristic region S1 that can be used for welding the current collecting plate is too small. Therefore, determining the battery cell to be unqualified can prevent defective products from flowing out.

[0035] In a specific embodiment, the first threshold range is greater than or equal to 17.5° and less than or equal to 22.5°, for example, it can be 17.5°, 19°, 20°, 21° or 22.5°; the second threshold range is greater than or equal to 35° and less than or equal to 55°, for example, it can be 35°, 40°, 45°, 50° and 55°, etc.; the third threshold range is greater than or equal to 35° and less than or equal to 55°, for example, it can be 35°, 40°, 45°, 50° and 55°, etc.

[0036] In a specific embodiment, each feature area S has an inner peripheral edge close to the reference point O and an outer peripheral edge away from the reference point O, and has a first center line and a second center line, the first center line is a line connecting the reference point O and the midpoint of the inner peripheral edge, and the second center line is a line connecting the reference point O and the midpoint of the outer peripheral edge; for example, referring to Figure 7, the positive characteristic region S1 has an inner peripheral edge V1 close to the reference point O, and has an outer peripheral edge V2 far away from the reference point O, the inner peripheral edge V1 and the outer peripheral edge V2 are both close to arcs, the line connecting the reference point O and the inner peripheral edge V1 forms a first center line L4, and the line connecting the reference point O and the outer peripheral edge V2 forms a second center line L5; the above method also includes: judging whether the angle between the first center line and the second center line of each characteristic region S is within the fourth threshold range, if not, the battery cell is judged to be unqualified. If the angle between the first center line L4 and the second center line L5 of the above positive characteristic region S1 is too large, it indicates that during the winding process of the battery cell, the position deviation between the outer ring positive pole ear P1 and the inner ring positive pole ear P1 is large, that is, the alignment is poor, therefore, this type of battery cell is judged to be unqualified, which can prevent defective products from flowing out. Among them, the fourth threshold range can be greater than or equal to 0° and less than or equal to 20°, for example, it can be 0°, 5°, 10°, 15° and 20°, etc. If the upper limit value of the fourth threshold range is too large, it may cause the battery cell with poor alignment of the tab P to flow out.

[0037] In a specific embodiment, the method further includes: determining whether the ratio of the area of ​​each characteristic region S to the area of ​​the corresponding ideal tab region T is within a fourth threshold range, and if not, determining that the battery cell is unqualified, wherein the two ideal tab regions T are symmetrically distributed on both sides of the reference line L1, and each ideal tab region T is spaced apart from the prohibited regions D on both sides in the circumferential direction, and the circumferential direction is the direction surrounding the reference point O. For example, reference Figure 4 and Figure 8 The positive electrode ideal lug region T1 corresponding to the positive electrode characteristic region S1 and the negative electrode ideal lug region T2 corresponding to the negative electrode characteristic region S2 are symmetrically distributed on both sides of the reference line L1. The positive electrode ideal lug region T1 is spaced apart from the prohibited region D1 and the prohibited region D2 in the circumferential direction, and the negative electrode ideal lug region T2 is spaced apart from the prohibited region D1 and the prohibited region D2 in the circumferential direction. The overlap between the positive electrode characteristic region S1 and the positive electrode ideal lug region T1 is determined by determining the ratio of the area of ​​the positive electrode characteristic region S1 to the area of ​​the positive electrode ideal lug region T1. If the area ratio is too small, it indicates that the positive electrode characteristic region S1 deviates from the positive electrode ideal lug region T1 by a large amount, and such battery cells are determined to be unqualified, which can prevent the outflow of defective battery cells.

[0038] In a specific embodiment, each ideal tab region T is a sector with the reference point O as the center. When there is no deviation between the inner and outer tabs P, the characteristic region S is a sector. The sector structure of the ideal tab region T is used as a standard figure for comparison with the characteristic region S, which can effectively feedback the degree of deviation of the characteristic figure. The circumferential angle corresponding to the ideal tab region T is between 40° and 50°, for example, it can be 40°, 45° and 50°, etc., wherein the symmetry axis of the ideal tab region T is perpendicular to the reference line L1. Among them, the positive ideal tab region T1 and the negative ideal tab region T2 can both be figures symmetrical about the vertical line L3, and the vertical line L3 passes through the reference point O and is perpendicular to the reference line L1.

[0039] In a specific embodiment, the fourth threshold range is greater than or equal to 80% and less than or equal to 100%, for example, it can be 80%, 85%, 90%, 95% and 100%, etc. If the lower limit of the fourth threshold range is too small, it may result in the failure to remove the battery cells with a large deviation between the characteristic area S and the ideal tab area T, resulting in the outflow of defective products.

[0040] In a specific embodiment, the method further includes: determining whether the area ratio of each characteristic region S to the area ratio of the corresponding dangerous region G is within a fifth threshold range, and if not, determining that the battery cell is unqualified, wherein a dangerous region G is set at adjacent positions on both sides of each prohibited region D in the circumferential direction, and the circumferential direction is the direction surrounding the reference point O. For example, referring to Figure 4 and Fig. 9 , with the reference point O as the origin, the reference line L1 as the horizontal axis, and the vertical line L3 as the vertical axis, a coordinate system is formed. The four dangerous areas G are the dangerous area G1 located in the first quadrant, the dangerous area G2 located in the second quadrant, the dangerous area G3 located in the third quadrant, and the dangerous area G4 located in the fourth quadrant. Taking the positive characteristic area S1 as an example, if the positive characteristic area S1 is located in the dangerous area G1 or the dangerous area G2 too much, that is, the area accounts for too much, it means that at least one side of the positive characteristic area S1 is too close to the negative characteristic area S2, which is easy to cause a short circuit. This type of battery cell is judged as unqualified, which can prevent the outflow of defective products.

[0041] In a specific embodiment, each dangerous area G is a sector with the reference point O as the center, and the corresponding circular angle is between 5° and 20°, for example, it can be 5°, 10°, 15° and 20°, etc. If the circular angle is too small, the characteristic area S is likely to occupy too large an area in the dangerous area G, and the characteristic area S is likely to enter the prohibited area D, resulting in the battery cells that meet the use requirements being judged as unqualified, causing waste. If the above circular angle is too large, it will occupy too much space in the prohibited area D or the ideal area T of the tab, resulting in qualified battery cells being included in defective products, or the defective products cannot be effectively eliminated.

[0042] In a specific embodiment, the fifth threshold range is greater than or equal to 0 and less than or equal to 50%, for example, it can be 50%, 40%, 30%, 20% and 15%. If the upper limit value is set too high, defective products whose two feature areas S are too close to each other may not be eliminated.

[0043] In a specific embodiment, when an ideal lug area T is provided between two prohibited areas D, the ideal lug area T is located between two dangerous areas G on the same side of the reference line L1, and is arranged adjacent to the dangerous area G. The three-level areas of the ideal lug area T, the dangerous area G that allows partial occupation, and the prohibited area D that is absolutely prohibited from being occupied are used to judge whether the characteristic area S is in a suitable position step by step. This can avoid excessive elimination of battery cells that meet the use requirements, and avoid the outflow of battery cells that do not meet the use requirements, and can achieve a better balance between the two.

[0044] refer to Fig.10 In a specific embodiment, the method further includes: determining whether each virtual welding area W is completely filled with the corresponding characteristic area S, and if not, determining that the battery cell is unqualified, wherein two virtual welding areas W are symmetrically arranged on both sides of the reference line L1 and are spaced apart from the reference line L1, and the virtual welding areas W are such as the positive electrode virtual welding area W1 corresponding to the positive electrode characteristic area S1 and the negative electrode virtual welding area W2 corresponding to the negative electrode characteristic area S2. If the virtual welding area W is not completely filled with the characteristic area S, it may cause the diaphragm welded to the surface of the end face 10 to be easily short-circuited with the electrode tab P and the electrode piece of different polarity when welding the collector plate and the tab P.

[0045] Based on the same inventive concept, an embodiment of the present application also provides a battery cell detection device, wherein the end face of the battery cell is provided with a pole ear P with opposite polarities; the battery cell detection device includes: an image acquisition unit and a processing unit; the image acquisition unit is used to acquire the end face image of the battery cell, identify two characteristic areas S corresponding to the pole ears of two polarities one to one, and determine the reference point O of the end face center according to the end face image, wherein the two characteristic areas S are arranged on both sides of the reference point O; the processing unit is used to adjust the end face image so that the arrangement direction of the two characteristic areas S is at a set angle b with the reference line L1, and the reference line L1 passes through the reference point O, and judge whether the two characteristic areas S overlap with the two prohibited areas D. If so, the battery cell is judged to be unqualified, wherein the two prohibited areas D are located on the reference line L1 and are symmetrically distributed on both sides of the reference point O. The area adjacent to the reference line L1 is designated as a prohibited area D. Once the positive characteristic area S1 overlaps with at least one of the prohibited area D1 and the prohibited area D2, or the negative characteristic area S2 overlaps with at least one of the prohibited area D1 and the prohibited area D2, it means that there is a risk that the positive characteristic area S1 and the negative characteristic area S2 are too close to each other. These battery cells will be regarded as seriously defective products and judged as unqualified, effectively screening out seriously defective products and preventing them from flowing out.

[0046] In a specific embodiment, each feature region S has two tangent lines passing through the reference point O, for example, Figure 6 , the positive characteristic region S1 has tangents L6 and L7 passing through the reference point O, and the negative characteristic region S2 has tangents L9 and L10 passing through the reference point O; the processing unit is also used for:

[0047] Determine whether the angle between each tangent and the reference line L1 is within the first threshold range. If not, the battery cell is determined to be unqualified. If the angle between the tangent L6 and the reference line L1 is too small, or the angle between the tangent L7 and the reference line L1 is too large, it indicates that the positive characteristic area S1 is too inclined to one side of the tangent L6, and the determination method of the tangent L9 and the tangent L10 is similar; Determine whether the angle between the adjacent tangents of the two characteristic areas S is within the second threshold range. If not, the battery cell is determined to be unqualified. For example, if the angle between the tangent L7 of the positive characteristic area S1 and the tangent L9 of the negative characteristic area S2 is too small, it indicates that the positive characteristic area S1 If the distance to the negative electrode characteristic area S2 is too close, a short circuit between the positive electrode tab P1 and the negative electrode tab P2 is likely to occur. Therefore, the battery cell is judged to be unqualified. It is determined whether the angle between the two tangents of each characteristic area S is within the third threshold range. If not, the battery cell is judged to be unqualified. For example, if the angle between the tangent L6 and the tangent L7 of the positive electrode characteristic area S1 is too large, it indicates that the misalignment between the positive electrode sheets of different layers in the positive electrode characteristic area S1 may be too large. If the angle between the tangent L6 and the tangent L7 is too small, it indicates that the area of ​​the positive electrode characteristic area S1 that can be used for welding the current collecting plate is too small. Therefore, the battery cell is judged to be unqualified to prevent defective products from flowing out.

[0048] In a specific embodiment, each feature area S has an inner peripheral edge close to the reference point O and an outer peripheral edge away from the reference point O, and has a first center line and a second center line, the first center line is a line connecting the reference point O and the midpoint of the inner peripheral edge, and the second center line is a line connecting the reference point O and the midpoint of the outer peripheral edge; for example, referring to Figure 7 , the positive characteristic region S1 has an inner peripheral edge V1 close to the reference point O, and has an outer peripheral edge V2 far away from the reference point O, the inner peripheral edge V1 and the outer peripheral edge V2 are both close to arcs, the line connecting the reference point O and the inner peripheral edge V1 forms a first center line L4, and the line connecting the reference point O and the outer peripheral edge V2 forms a second center line L5; the processing unit is also used to: determine whether the angle between the first center line and the second center line of each characteristic region S is within the fourth threshold range, if not, the battery cell is determined to be unqualified. If the angle between the first center line L4 and the second center line L5 of the above-mentioned positive characteristic region S1 is too large, it indicates that during the winding process of the battery cell, the position deviation between the outer ring of the positive pole ear P1 and the inner ring of the positive pole ear P1 is large, that is, the alignment is poor, therefore, this type of battery cell is determined to be unqualified, which can prevent defective products from flowing out. Among them, the fourth threshold range can be greater than or equal to 0° and less than or equal to 20°, for example, it can be 0°, 5°, 10°, 15° and 20°, etc. If the upper limit value of the fourth threshold range is too large, it may cause the battery cell with poor alignment of the tab P to flow out.

[0049] In a specific embodiment, the processing unit is further used to: determine whether the ratio of the area of ​​each characteristic region S to the area of ​​the corresponding ideal tab region T is within a fourth threshold range, and if not, determine that the battery cell is unqualified, wherein the two ideal tab regions T are symmetrically distributed on both sides of the reference line L1, and each ideal tab region T is spaced from the prohibited regions D on both sides in the circumferential direction, and the circumferential direction is the direction around the reference point O. For example, reference Figure 4 and Figure 8 The positive electrode ideal lug region T1 corresponding to the positive electrode characteristic region S1 and the negative electrode ideal lug region T2 corresponding to the negative electrode characteristic region S2 are symmetrically distributed on both sides of the reference line L1. The positive electrode ideal lug region T1 is spaced apart from the prohibited region D1 and the prohibited region D2 in the circumferential direction, and the negative electrode ideal lug region T2 is spaced apart from the prohibited region D1 and the prohibited region D2 in the circumferential direction. The overlap between the positive electrode characteristic region S1 and the positive electrode ideal lug region T1 is determined by determining the ratio of the area of ​​the positive electrode characteristic region S1 to the area of ​​the positive electrode ideal lug region T1. If the area ratio is too small, it indicates that the positive electrode characteristic region S1 deviates from the positive electrode ideal lug region T1 by a large amount, and such battery cells are determined to be unqualified, which can prevent the outflow of defective battery cells.

[0050] In a specific embodiment, the processing unit is further used to: determine whether the area ratio of each characteristic region S to the area ratio of the corresponding dangerous region G is within the fifth threshold range, and if not, determine that the battery cell is unqualified, wherein a dangerous region G is set at adjacent positions on both sides of each prohibited region D in the circumferential direction, and the circumferential direction is the direction surrounding the reference point O. For example, referring to Figure 4 and Fig. 9 , with the reference point O as the origin, the reference line L1 as the horizontal axis, and the vertical line L3 as the vertical axis, a coordinate system is formed. The four dangerous areas G are the dangerous area G1 located in the first quadrant, the dangerous area G2 located in the second quadrant, the dangerous area G3 located in the third quadrant, and the dangerous area G4 located in the fourth quadrant. Taking the positive characteristic area S1 as an example, if the positive characteristic area S1 is located in the dangerous area G1 or the dangerous area G2 too much, that is, the area accounts for too much, it means that at least one side of the positive characteristic area S1 is too close to the negative characteristic area S2, which is easy to cause a short circuit. This type of battery cell is judged as unqualified, which can prevent the outflow of defective products.

[0051] In a specific embodiment, the processing unit is further used to: determine whether each virtual welding area W is completely filled with the corresponding characteristic area S, and if not, determine that the battery cell is unqualified, wherein the two virtual welding areas W are symmetrically arranged on both sides of the reference line L1 and are spaced apart from the reference line L1. If the virtual welding area W is not completely filled with the characteristic area S, it may cause the diaphragm welded to the surface of the end face 10 to short-circuit with the pole piece of different polarity with the pole piece P when welding the collector plate and the pole tab P.

[0052] Based on the same inventive concept, an embodiment of the present application also provides a cell correction method based on the cell detection method provided in the above embodiment, and the cell correction method includes: when the absolute value of the difference between the initial angle a and the set angle b is greater than 0, controlling the driving component to drive the cell to rotate the angle of the difference to perform preliminary correction on the cell, and the rotation direction of the cell is the same as the rotation direction of the end face image, wherein the initial angle refers to the angle between the arrangement direction of the two feature areas S before the end face image is rotated and the reference line L1; when the focus parts of the two feature areas S are located on the same side of the reference point O in the direction of the reference line L1, rotating the cell so that the focus parts of the two feature areas S are equal in area or the corresponding circular angles are the same, thereby dispersing the alignment deviation of the cell to the two feature areas, so that the position deviation of the two feature areas is minimized as much as possible, and the circular angle corresponding to each focus part refers to the tangent of the focus part passing through the reference point O The angle between the line and the boundary of the corresponding dangerous area G, such as the angle d formed by the tangent line L0 of the focus part of the positive characteristic area S located in the dangerous area G1 and the corresponding boundary of the dangerous area G1, is the circumferential angle corresponding to the focus part of the positive characteristic area S1; or, when the focus parts of two characteristic areas S are located on different sides of the reference point O in the direction of the reference line L1, the battery cell is rotated so that the areas of the characteristic areas S in the four dangerous areas G tend to be close, so that the alignment deviation of the battery cell is dispersed to the two characteristic areas, so that the position deviation of the two characteristic areas is minimized as much as possible; wherein, the focus part refers to a larger part of the overlapping part of each characteristic area S with the dangerous areas G on both sides, for example, the overlapping area of ​​the positive characteristic area S1 with the dangerous area G1 is larger than the overlapping area with the dangerous area G2, then the overlapping part of the positive characteristic area S1 with the dangerous area G1 is the focus part of the positive characteristic area S1.

[0053] For example, refer to Fig.11 , in a specific battery cell production line, the following steps are performed in sequence:

[0054] S1. Using a winding mechanism to wind a pole piece assembly to form a battery cell, the pole piece assembly includes positive pole pieces and negative pole pieces that are alternately arranged in sequence, a separator is provided between the positive pole pieces and the negative pole pieces, and the battery cell tab P formed by winding stands on the end surface 10 of the battery cell and has not been flattened;

[0055] S2, unloading the wound battery cell to a conveying mechanism, such as a conveyor belt;

[0056] S3, after the battery cell is transferred to the first inspection station, the battery cell inspection method is used to inspect whether the battery cell is qualified. If it is unqualified, step S31 is executed to discard the unqualified battery cell. Otherwise, step S4 is executed;

[0057] S4, using the cell deviation correction method provided in the above embodiment to correct the cell deviation, so that the tab P can be aligned with the leveling mechanism;

[0058] S5, controlling the flattening mechanism to flatten the tab P, for example, by gradually pushing down the tab P from the outer periphery to the reference point O along the radial direction of the end face 10 of the battery cell through the flattening structure with an arc-shaped notch, so that the tab P falls on the end face 10 of the battery cell to facilitate subsequent welding with the collector plate;

[0059] S6, after the battery cell is transferred to the second inspection station, the battery cell inspection method is used to inspect whether the battery cell is qualified. If it is unqualified, step S61 is executed to discard the unqualified battery cell. Otherwise, step S7 is executed;

[0060] S7. Use the cell correction method provided in the above embodiment to correct the cell so that the tab P can be rotated to the angle required for unloading. The correction mechanism used can be a cell picking robot arm.

[0061] Wherein, both step S3 and step S6 can be detected by CCD (Charge-Coupled Device).

[0062] When executing the above-mentioned battery cell detection method in step S3, the following method can be used: Fig.12 The image acquisition unit shown. Fig.12 The image acquisition unit includes a camera 03 and a light source 02. The camera 03 can be an industrial array camera with the above-mentioned charge coupled device, and is arranged toward the end face 10 of the battery cell 01. The camera 03 and the light source 02 can be arranged coaxially with the battery cell 01, and the light source 02 has a channel in the middle for transmitting light to the camera 03. The light source 02 here can be a 0° blue annular light source, so that the edge of the standing tab P can reflect light, thereby facilitating the identification of the characteristic area S of the tab P. The distance from the light source 02 to the end face 10 can be between 5 mm and 20 mm, for example, it can be 5 mm, 10 mm, 15 mm, and 20 mm, etc. If the distance is too close, the light source 02 may interfere with the tab P, and it is difficult for the camera 03 to capture the edge of the tab P. If the distance is too large, it is difficult for the light source 02 to illuminate the edge of the tab P.

[0063] When executing the above-mentioned battery cell detection method in step S6, the following method may be used: Fig.13 The image acquisition unit shown. Fig.13 ,and Fig.12 The difference between the image acquisition units shown is that the camera 03 can use an industrial FA (Factory Automation) lens, and the light source 02 uses a spherical integrating light source, so that the light can evenly illuminate the end face 10 of the battery cell 01, so that the flattened pole ear P can evenly reflect light.

[0064] Furthermore, in step S3 and step S6, the overall deviation trend of the tab P can be statistically calculated based on the detection results of multiple battery cells, and the deviation trend can be fed back to the winding mechanism for adaptive deviation correction by the winding mechanism.

[0065] Obviously, those skilled in the art can make various changes and modifications to the embodiments of the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A battery cell detection method, characterized in that: The end surface of the battery cell is provided with a pole ear with opposite polarity; The method comprises: Acquire an end face image of the battery cell, identify two characteristic regions corresponding to the tabs of two polarities, and determine a reference point at the center of the end face according to the end face image, wherein the two characteristic regions are arranged on both sides of the reference point; Rotating the end face image so that the arrangement direction of the two characteristic regions forms a set angle with a reference line, and the reference line passes through the reference point; Determine whether the two characteristic areas overlap with the two prohibited areas, and if so, determine that the battery cell is unqualified, wherein the two prohibited areas are located on the reference line and symmetrically distributed on both sides of the reference point; Each of the forbidden areas is a sector with the reference point as the center and the reference line as the axis of symmetry, and the circumferential angle corresponding to the forbidden area is between 5° and 20°; The set angle is between 85° and 95°.

2. The battery cell detection method according to claim 1, characterized in that: Each of the characteristic regions has two tangent lines passing through the reference point; The method further comprises: Determine whether the angle between each of the tangent lines and the reference line is within a first threshold range, and if not, determine that the battery cell is unqualified; Determine whether the angle between the adjacent tangent lines of the two characteristic regions is within a second threshold range, and if not, determine that the battery cell is unqualified; It is determined whether the angle between the two tangent lines of each characteristic region is within a third threshold range; if not, the battery cell is determined to be unqualified.

3. The battery cell detection method according to claim 2, characterized in that: The first threshold range is greater than or equal to 17.5° and less than or equal to 22.5°; The second threshold range is greater than or equal to 35° and less than or equal to 55°; The third threshold range is greater than or equal to 35° and less than or equal to 55°.

4. The battery cell detection method according to claim 1, characterized in that: Each of the feature areas has an inner peripheral edge close to the reference point and an outer peripheral edge far from the reference point, and has a first center line and a second center line, the first center line is a line connecting the reference point and the midpoint of the inner peripheral edge, and the second center line is a line connecting the reference point and the midpoint of the outer peripheral edge; The method further comprises: It is determined whether the angle between the first center line and the second center line of each of the characteristic regions is within a fourth threshold range; if not, the battery cell is determined to be unqualified.

5. The battery cell detection method according to claim 4, characterized in that: The fourth threshold range is greater than or equal to 0° and less than or equal to 20°.

6. The battery cell detection method according to any one of claims 1 to 5, characterized in that: The method further comprises: Determine whether the ratio of the area of ​​each of the characteristic regions to the area of ​​the corresponding ideal lug region is within a fourth threshold range; if not, determine that the battery cell is unqualified, wherein the two ideal lug regions are symmetrically distributed on both sides of the reference line, and each of the ideal lug regions is spaced apart from the prohibited regions on both sides in the circumferential direction, and the circumferential direction is the direction surrounding the reference point.

7. The battery cell detection method according to claim 6, characterized in that: Each of the ideal tab regions is a sector with the reference point as the center, and the corresponding circumferential angle is between 40° and 50°, wherein the symmetry axis of the ideal tab region is perpendicular to the reference line.

8. The battery cell detection method according to claim 6, characterized in that: The fourth threshold range is greater than or equal to 80% and less than or equal to 100%.

9. The battery cell detection method according to any one of claims 1 to 8, characterized in that: The method further comprises: Determine whether the area ratio of each characteristic area to the corresponding danger area is within the fifth threshold range; if not, determine that the battery cell is unqualified, wherein one danger area is set at adjacent positions on both sides of each prohibited area in the circumferential direction, and the circumferential direction is the direction surrounding the reference point.

10. The battery cell detection method according to claim 9, characterized in that: Each of the danger zones is a sector with the reference point as the center, and the corresponding circular angle is between 5° and 20°.

11. The battery cell detection method according to claim 9, characterized in that: The fifth threshold range is greater than or equal to 0 and less than or equal to 50%.

12. The battery cell detection method according to claim 9, characterized in that: When an ideal tab area is provided between two prohibited areas, the ideal tab area is located between the two dangerous areas on the same side of the reference line and is provided adjacent to the dangerous area.

13. The battery cell detection method according to any one of claims 1 to 12, characterized in that: The method further comprises: It is determined whether each virtual welding area is completely filled by the corresponding characteristic area. If not, the battery cell is determined to be unqualified, wherein the two virtual welding areas are symmetrically arranged on both sides of the reference line and are spaced apart from the reference line.

14. A battery cell detection device, characterized in that: The end surface of the battery cell is provided with a pole ear with opposite polarity; The battery cell detection device comprises: an image acquisition unit and a processing unit; The image acquisition unit is used to acquire the end face image of the battery cell, identify two characteristic regions corresponding to the pole ears of two polarities one to one, and determine the reference point of the center of the end face according to the end face image, wherein the two characteristic regions are arranged on both sides of the reference point; The processing unit is used to adjust the end face image so that the arrangement direction of the two characteristic areas is at a set angle with the reference line, and the reference line passes through the reference point, and judge whether the two characteristic areas overlap with the two prohibited areas. If so, the battery cell is judged to be unqualified, wherein the two prohibited areas are located on the reference line and symmetrically distributed on both sides of the reference point; Each of the forbidden areas is a sector with the reference point as the center and the reference line as the axis of symmetry, and the circumferential angle corresponding to the forbidden area is between 5° and 20°; The set angle is between 85° and 95°.

15. The battery cell detection device according to claim 14, characterized in that: Each of the characteristic regions has two tangent lines passing through the reference point; The processing unit is also used for: Determine whether the angle between each of the tangent lines and the reference line is within a first threshold range, and if not, determine that the battery cell is unqualified; Determine whether the angle between the adjacent tangent lines of the two characteristic regions is within a second threshold range, and if not, determine that the battery cell is unqualified; It is determined whether the angle between the two tangent lines of each characteristic region is within a third threshold range; if not, the battery cell is determined to be unqualified.

16. The battery cell detection device according to claim 14, characterized in that: Each of the feature areas has an inner peripheral edge close to the reference point and an outer peripheral edge far from the reference point, and has a first center line and a second center line, the first center line is a line connecting the reference point and the midpoint of the inner peripheral edge, and the second center line is a line connecting the reference point and the midpoint of the outer peripheral edge; The processing unit is also used for: It is determined whether the angle between the first center line and the second center line of each of the characteristic regions is within a fourth threshold range; if not, the battery cell is determined to be unqualified.

17. The battery cell detection device according to claim 14, characterized in that: The processing unit is also used for: Determine whether the ratio of the area of ​​each of the characteristic regions to the area of ​​the corresponding ideal lug region is within a fourth threshold range; if not, determine that the battery cell is unqualified, wherein the two ideal lug regions are symmetrically distributed on both sides of the reference line, and each of the ideal lug regions is spaced apart from the prohibited regions on both sides in the circumferential direction, and the circumferential direction is the direction surrounding the reference point.

18. The battery cell detection device according to claim 14, characterized in that: The processing unit is also used for: Determine whether the area ratio of each characteristic area to the corresponding danger area is within the fifth threshold range; if not, determine that the battery cell is unqualified, wherein one danger area is set at adjacent positions on both sides of each prohibited area in the circumferential direction, and the circumferential direction is the direction surrounding the reference point.

19. The battery cell detection device according to claim 14, characterized in that: The processing unit is also used for: It is determined whether each virtual welding area is completely filled by the corresponding characteristic area. If not, the battery cell is determined to be unqualified, wherein the two virtual welding areas are symmetrically arranged on both sides of the reference line and are spaced apart from the reference line.

20. A cell deviation correction method based on the cell detection method according to any one of claims 9 to 12, characterized in that: include: When the absolute value of the difference between the initial angle and the set angle is greater than 0, the driving component is controlled to drive the battery cell to rotate by the angle of the difference, and the rotation direction of the battery cell is the same as the rotation direction of the end face image, wherein the initial angle refers to the angle between the arrangement direction of the two characteristic areas before the end face image is rotated and the reference line; When the focus portions of the two characteristic regions are located on the same side of the reference point in the reference line direction, the battery cell is rotated so that the focus portions of the two characteristic regions have equal areas or the corresponding circumferential angles are the same; or When the concerned parts of two characteristic regions are located on different sides of the reference point in the direction of the reference line, rotating the battery cell so that the characteristic regions in the four dangerous regions tend to be close in area; The focus portion refers to a portion with a larger area among the overlapping portions of each of the feature regions and the dangerous regions on both sides.

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