Apparatus for inspecting unit cell electrode alignment

Abstract

The electrode alignment inspection device of a unit cell according to the disclosed invention comprises an LWIR vision unit (10), an alignment vision unit (20), a correction transfer unit (30), and a stack vision unit (40). The LWIR vision unit (10) is installed near a conveyor (60) through which a unit cell (50) is transported, and measures the position of the cathode equipped in the unit cell by irradiating and photographing each of the four corner portions of the unit cell with long-wavelength infrared (LWIR). The alignment vision unit (20) is installed near the conveyor so as to be located behind the LWIR vision unit (10) on the movement path of the unit cell, receives cathode position data measured from the LWIR vision unit (10), calculates the cell center position based on the cathode using the received cathode position data, and calculates an alignment correction value. The correction transfer unit (30) receives the alignment correction value from the alignment vision unit (20), transfers the unit cell by the received alignment correction value, and stacks it on the stacking table (70). The stack vision unit (40) is installed near the stacking table, measures the positive position of the stacked unit cell, receives negative position data from the alignment vision unit, and uses the measured and received positive position data and negative position data to measure the distance between the positive and negative (or negative and positive) of two adjacent unit cells, and calculates the degree of alignment between the electrodes of the unit cells based on the negative.

Description

Technology Field

[0001] The present invention relates to an apparatus for inspecting the electrode alignment of a unit cell constituting a secondary battery, and more particularly to an apparatus for inspecting the electrode alignment of a unit cell in real time during a unit cell stacking process. Background Technology

[0002] Rechargeable secondary batteries are broadly classified into cylindrical batteries, prismatic batteries, pouch-type batteries, etc., depending on their external shape. Here, in the pouch-type battery, an electrode assembly is housed in a pouch-type case, and an electrolyte, which is a liquid electrolyte, is injected into the pouch-type case and then sealed. A pouch-type battery in this sealed state is referred to as a packaging cell.

[0003] The above electrode assembly includes one or more unit cells, and the unit cells have a structure in which a first electrode (anode) and a second electrode (cathode) are alternately arranged with a separator.

[0004] Meanwhile, lithium secondary batteries using electrolytes pose a fire risk due to explosion, and the main causes are known to be overhang-related issues, such as compression caused by folding of the negative electrode plate or abnormal protrusions within the positive tab of the positive electrode plate penetrating the insulation tape and separator. Therefore, to ensure safety, manufacturers need to inspect whether the positions of the separator, positive electrode, and negative electrode are damaged and whether they are properly aligned in the correct positions during the manufacturing process.

[0005] Conventional general inspection devices involve disassembling secondary batteries to directly measure internal voltage, current, and resistance, but this makes it impossible to conduct a full inspection of all batteries. Therefore, non-destructive inspection based on X-ray and CT scans has recently been applied; however, since this also requires moving the battery to the inspection equipment for inspection, it is time-consuming to conduct a full inspection, so it is currently being used to solve battery yield issues.

[0006] Therefore, a method for inspecting batteries in real time has recently been introduced; specifically, a method in which cameras are installed on the conveyor belt through which unit cells are transported and on the table where the unit cells are stacked during the MonoCell Stack process, and inspection is performed using the camera images.

[0007] However, as mentioned above, the separator of the unit cell must be present between the electrodes. Since the separator is made of a translucent material, light is transmitted, diffused, and reflected. Consequently, if the separator is lifted or wrinkled between the electrodes, light spreads out, causing the electrodes to become invisible. Although a lifted separator does not result in a product defect, it prevents the electrodes from being measured normally, leading to over-inspection or under-inspection. Therefore, measuring the electrodes without being affected by the condition of the separator in inspection methods using camera images has long been a difficult challenge.

[0008] Electromagnetic waves are classified into infrared, visible light, and ultraviolet rays depending on their wavelength bands. Since the greater the illumination wavelength, the better the degree of penetration, it is advantageous to apply infrared cameras. However, even within infrared, the characteristics differ for each wavelength of NIR (near-infrared), SWIR (short-wave infrared), MWIR (medium-wave infrared), and LWIR (long-wave infrared), so the materials of camera sensors and lenses differ. In particular, it is known that electromagnetic waves in the LWIR wavelength band penetrate the separator material well, allowing electrodes to be measured without being affected by the condition of the separator. Therefore, a method of inspecting secondary batteries using an LWIR optical system, as described in the prior art below, has recently been introduced.

[0009] That is, due to the characteristics of a unit cell composed of an anode, a separator, a cathode, and a separator in that order, the cathode must pass through the separator to be measured. When a light source is irradiated onto the unit cell to measure as shown in Fig. 1, if the light source is in the general visible light or infrared wavelength range, the cathode is not clearly visible as shown in Fig. 2a, but if the light source is in the LWIR wavelength range, the cathode is clearly visible as shown in Fig. 2b. Prior art literature

[0010] Republic of Korea Published Patent Application No. 10-2022-0103458 (Published July 22, 2022) Republic of Korea Published Patent Application No. 10-2023-0031060 (Published March 7, 2023) The problem to be solved

[0011] The present invention has been devised in consideration of the above points, and aims to provide a device that measures a cathode using an LWIR optical system in a unit cell stacking process and inspects the electrode alignment of a unit cell in real time using the measured cathode position. means of solving the problem

[0012] A device for inspecting the electrode alignment of a unit cell according to the present invention for achieving the above objective comprises: an LWIR vision unit installed near a conveyor through which a unit cell is transported, which measures the position of a cathode equipped in the unit cell by irradiating and photographing each of the four corner portions of the unit cell with long-wavelength infrared (LWIR); an alignment vision unit installed near the conveyor so as to be positioned behind the LWIR vision unit on the movement path of the unit cell, which receives cathode position data measured by the LWIR vision unit, calculates the cell center position relative to the cathode using the received cathode position data, and calculates an alignment correction value; and a correction transport unit that receives the alignment correction value from the alignment vision unit, transports the unit cell by the amount of the received alignment correction value, and stacks it on a stacking table. and, a stack vision unit installed near the stacking table, which measures the anode position of the stacked unit cell and receives cathode position data from the alignment vision unit, and calculates the degree of alignment between electrodes between unit cells based on the cathode by measuring the distance between the anode and cathode (or cathode and anode) of two adjacent unit cells using the measured and received anode position data and cathode position data.

[0013] The above LWIR vision unit can measure a total of 8 cathode positions (A, B, C, D, E, F, G, H) by measuring points located at a certain distance along the X-axis and Y-axis from the corner points of each corner of the unit cell at each corner section.

[0014] The above alignment vision unit measures the four corner points (F1(x1,y1), F2(x2,y2), F3(x3,y3), F4(x4,y4)) of each unit cell using the cathode positions (A, B, C, D, E, F, G, H) received from the LWIR vision, and then the cell center position (F) relative to the cathode x , F y , F θ) is calculated as shown in the following mathematical formula.

[0015]

[0016]

[0017]

[0018] Here, F1(x1,y1) is an extension of and The intersection point of the extension line, F2(x2,y2), is extension and The intersection point of the extension line, F3(x3,y3), is an extension of and The intersection point of the extension line, F4(x4,y4), is an extension of and It means the intersection point of the extension of.

[0019] The above alignment vision unit is the rotation center (R(R) of the arm of the transfer part of the above correction transfer unit. x , R y Center of the unit cell (F) based on )) x , F y The center of the unit cell after rotating ) by θ (F'(F' x , F' y Calculate )) as shown in the following mathematical formula, and

[0020]

[0021]

[0022] Next, the center of the unit cell after rotation obtained by the above mathematical formula (F'(F' x , F' y )) Stack center position (S x , S y , S θ The final alignment correction value that the transfer unit moves to based on the position that the transfer unit moves to, that is, the stack center position, is calculated as shown in the following mathematical formula.

[0023]

[0024]

[0025]

[0026] Here, θ is S, the tilted angle of the stack center. θ F, which is the tilted angle of the center of the unit cell. θ It means the value after subtracting.

[0027] The above stack vision unit can calculate the distance (CA 1, 2) between the positive and negative electrodes of two adjacent unit cells (C1, C2) as shown in the following mathematical formula.

[0028]

[0029] Here, AC represents the distance between the anode and the cathode within a single unit cell, and C-Pos(Position) represents the position of the anode. Effects of the invention

[0030] According to the present invention, in a stacking process for forming an electrode assembly by stacking unit cells, the position of the electrode, particularly the cathode, of a unit cell transported by a conveyor is measured using an LWIR (long-wave infrared) optical system, and the alignment value of the unit cell is corrected using this method and positioned on a stacking table. Then, during the stacking process on the stacking table, the distance between the anode and cathode of two adjacent unit cells is measured, and the degree of alignment between the electrodes of the unit cells is calculated based on the cathode, thereby enabling real-time overhang inspection. Brief explanation of the drawing

[0031] FIG. 1 is a diagram for explaining measurement by irradiating a unit cell with a light source, FIG. 2a shows a unit cell when the light source is in the general visible light or infrared wavelength band, and FIG. 2b shows a unit cell when the light source is in the LWIR wavelength band. FIG. 3 is a block diagram of an electrode alignment inspection device of a unit cell according to an embodiment of the present invention, FIG. 4 is a schematic configuration diagram of an electrode alignment inspection device of a unit cell according to an embodiment of the present invention, illustrating that an LWIR vision unit measures a unit cell and transmits cathode position data to an alignment vision unit. FIG. 5 is a diagram illustrating an LWIR vision unit measuring a unit cell. FIG. 6 is a diagram illustrating an alignment vision unit calculating the cathode center position, FIG. 7 is a schematic configuration diagram of an electrode alignment inspection device of a unit cell according to an embodiment of the present invention, illustrating that an alignment vision unit transmits cathode data and transmits a final alignment correction value to a correction transfer unit. FIGS. 8 and 9 are drawings illustrating the alignment controller of an alignment vision unit calculating a final alignment correction value. FIG. 10 is a schematic diagram of an electrode alignment inspection device for a unit cell according to an embodiment of the present invention, illustrating that a correction transfer unit transfers a unit cell to a stacking table according to a received alignment correction value. FIG. 11 is a schematic diagram of a unit cell electrode alignment inspection device according to an embodiment of the present invention, illustrating a stack vision unit calculating the distance between electrodes of unit cells stacked on a stacking table. Figure 12 is a diagram illustrating how a stack vision unit calculates the distance between the electrodes of two adjacent unit cells to obtain an electrode alignment diagram. Specific details for implementing the invention

[0032] The above-mentioned objectives, features, and other advantages of the present invention will become more apparent by describing preferred embodiments of the present invention in detail with reference to the accompanying drawings. Hereinafter, an electrode alignment inspection device for a unit cell according to an embodiment of the present invention will be described in detail with reference to the attached drawings.

[0033] As described above, the electrode assembly has a structure in which one or more unit cells are arranged in an upward or downward direction, and the unit cells have a structure in which a first electrode (anode) and a second electrode (cathode) are alternately arranged with a separator interposed therebetween. The electrodes included in the unit cells include an anode and a cathode, wherein the cathode has a larger area than the anode and the separator has a larger area than the cathode, and the electrode assembly has a structure in which the unit cells are stacked in multiple layers based on the cathode included in the unit cells.

[0034] The electrode alignment inspection device of a unit cell according to an embodiment of the present invention measures the position of the electrode, particularly the cathode, of a unit cell transported by a conveyor during a stacking process in which unit cells are stacked to form an electrode assembly using an LWIR (long-wave infrared) optical system, corrects the alignment value of the unit cell using this measurement and positions it on a stacking table, and then calculates the alignment between the electrodes of the unit cell during the stacking process on the stacking table to perform an overhang inspection in real time. The present invention will be described in detail below.

[0035] Referring to FIG. 3, the electrode alignment inspection device of a unit cell according to an embodiment of the present invention includes an LWIR vision unit (10), an alignment vision unit (20), a correction transfer unit (30), and a stack vision unit (40).

[0036] Referring to FIGS. 3 and 4, the LWIR vision unit (10) irradiates and photographs each of the four corner portions of the unit cell (50) with long-wavelength infrared (LWIR) to measure the position of the electrodes including the positive and negative electrodes provided in the unit cell.

[0037] The LWIR vision unit (10) includes an LWIR vision (12) and an LWIR controller (14).

[0038] LWIR vision (12) is installed at a certain position on the upper part of the conveyor (60) through which the unit cell (50) is transported, and a total of four are installed: two at regular intervals on the upper part of the conveyor (60) and two at regular intervals on the lower part of the conveyor to photograph the four corner portions of the unit cell (50). Each LWIR vision (12) may include a first LWIR lamp (for coaxial lighting) located at the upper front of the conveyor to heat the upper surface of the corner portion of the unit cell (50), a second LWIR lamp (for backlighting) located at the lower rear of the conveyor to heat the rear surface of the corner portion of the unit cell (50), and an LWIR camera located at the upper part of the first LWIR lamp to photograph a thermal image of the corner portion of the unit cell (50).

[0039] The first and second LWIR lamps above are light sources that emit LWIR (Long-wave Infrared) to illuminate and heat the object. LWIR is an electromagnetic wave with a wavelength of approximately 7 to 15 nm. Through experiments conducted by the applicant, it was confirmed that electromagnetic waves in the LWIR wavelength range penetrate the separator material well, allowing the electrode to be measured without being affected by the condition of the separator. The LWIR camera captures the corner of the unit cell (50) using LWIR to obtain a thermal image of the corner of the unit cell.

[0040] As shown in FIG. 5, each of the four LWIR visions (12) measures the location of two points at each corner of the corresponding location, and thus the LWIR visions (12) measure a total of eight locations. That is, points (hereinafter referred to as 'measurement points') located a certain distance away from the corner point of each corner in the X-axis and Y-axis are measured. According to an embodiment of the present invention, points located 5 mm away from the corner point of each corner in the X-axis and Y-axis are designated as measurement points (A, B, C, D, E, F, G, H).

[0041] The LWIR controller (14) measures eight cathode positions from the image received from each LWIR vision (12) and transmits the cathode position data (Data) to the alignment vision unit (20).

[0042] Referring again to FIGS. 3 and FIGS. 4, the alignment vision unit (20) receives cathode position data measured from the LWIR vision unit (10), uses this to calculate the cell center position relative to the cathode, and then calculates an alignment correction value.

[0043] The alignment vision unit (20) includes an alignment vision (22) and an alignment controller (24).

[0044] The alignment vision (22) is installed on the upper part of the conveyor (60) so as to be located behind the LWIR vision unit (10) on the movement path of the unit cell (50), and serves to detect the unit cell (50) being transported on the conveyor (60), and typically an ultraviolet or infrared camera may be applied.

[0045] The alignment controller (24) receives cathode position data from the LWIR controller (14) of the LWIR vision unit (10) and uses it to calculate the cathode-referenced cell center position. Meanwhile, the alignment controller (24) transmits the cathode position data received from the LWIR controller (14) to the correction transfer unit (30). The method by which the alignment controller (24) calculates the cathode-referenced cell center position is as follows.

[0046] Referring to FIG. 6, the alignment controller (24) receives cathode position data of 8 points (A, B, C, D, E, F, G, H) received from the LWIR vision unit (10), and uses this to measure the 4 corner points (F1(x1,y1), F2(x2,y2), F3(x3,y3), F4(x4,y4)) of the unit cell. For each of the 4 corner points, F1(x1,y1) is an extension of and The intersection point of the extension line, F2(x2,y2), is extension and The intersection point of the extension line, F3(x3,y3), is an extension of and The intersection point of the extension line, F4(x4,y4), is an extension of and Each can be obtained from the intersection point of the extension line.

[0047] After that, from the 4 corner points (F1(x1,y1), F2(x2,y2), F3(x3,y3), F4(x4,y4) obtained from above, the center position (F) of the unit cell x , F y , F θ ) can be calculated as shown in the equation below.

[0048]

[0049]

[0050]

[0051] Here, ∠(F1~F3) is the angle formed by the line segment connecting points F1 and F2 (defined as 0 when perpendicular), and ∠(F2~F4) is the angle formed by the line segment connecting points F2 and F4 (defined as 0 when perpendicular), and therefore F θ represents the average value of the inclined angles of the two long sides of the unit cell.

[0052] Then, the final alignment correction value is calculated using the center position of the unit cell obtained from the above mathematical formula 1. Here, the final alignment correction value refers to the measured center position of the unit cell (F x , F y , F θ ) measured Stack center position (S x , S y , S θ It refers to the movement value for sending to ). The above Stack center position (S x , S y , S θ ) may be the center position of the alignment vision (42) of the alignment vision unit (20).

[0053] Referring to FIGS. 3 and 7, the correction transfer unit (30) receives the alignment correction value from the alignment vision unit (20) and transfers the unit cell by the amount of the received alignment correction value to stack it on a stacking table. Specifically, it includes a transfer unit (32) that transfers the unit cell and a transfer controller (34) that receives the alignment correction value from the alignment vision unit (20) and controls the transfer unit (32) to transfer by the amount of the alignment correction value.

[0054] The order in which the alignment vision unit (20) obtains the final alignment correction value is as follows.

[0055] First, referring to FIGS. 8 and 9, the rotation center (R(R) of the arm of the transfer unit (32) x , R y Center of the unit cell (F) based on )) x , F y If ) is rotated by θ, the center of the unit cell after rotation (F'(F' x , F' y )) is equal to Equation 2 below. Here, θ is S, the tilted angle of the Stack center. θ F, which is the tilted angle of the center of the unit cell. θ The value minus, i.e., θ = S θ - F θ It means.

[0056]

[0057]

[0058] Next, the center of the unit cell after rotation obtained by the above mathematical formula 2 (F'(F' x , F' y )) Stack center position (S x , S y , S θ The final alignment correction value that the transfer unit (32) moves to based on the stack center position, i.e., the position to which the transfer unit (32) moves, is equal to the following mathematical formula 3.

[0059]

[0060]

[0061]

[0062] As described above and illustrated in FIG. 10, the correction transfer unit (30) receives the alignment correction value from the alignment vision unit (20) and transfers the unit cell by the received alignment correction value to stack it on the stacking table (70).

[0063] Referring to FIGS. 3 and FIGS. 11, the stack vision unit (40) measures the alignment degree between the positive and negative electrodes (or between the negative and positive electrodes) in real time using positive position data and negative position data of the unit cells stacked on the stacking table (70), and specifically includes a stack vision (42) and a stack controller (44). Here, unit cells are stacked on the stacking table (70) in a stack quantity determined by model.

[0064] Stack vision (42) is installed on the upper part of the stacking table (70) and measures the positive position of the stacked unit cell, and a camera is usually applied.

[0065] As described above, the stack controller (44) receives the negative position data of the unit cell from the alignment controller (24) of the alignment vision unit (20), and uses the received negative position data and the measured positive position data to measure the degree of alignment between the electrodes between the positive and negative (or the negative and positive) in real time.

[0066] The stack controller (44) measures the alignment between the electrodes based on the negative position as follows.

[0067] Referring to FIGS. 11 and 12, the unit cell located at the top among the unit cells stacked on the stacking table (70), that is, the most recently stacked unit cell, is denoted as C2, and the unit cell located below it is denoted as C1. When AC represents the distance between the anode and the cathode within a unit cell and C-Pos (Position) represents the position of the cathode, AC1, AC2, C-Pos1, and C-Pos2 are as shown in the drawings. As illustrated, adjacent unit cells (C1, C2) are stacked alternately with the anode and cathode based on the separator.

[0068] Here, C-Pos can be measured by stack vision (42), and AC is measured by LWIR vision unit (10) and received from alignment vision unit (20).

[0069] Ultimately, the degree of alignment between electrodes of adjacent unit cells (relative to the cathode) can be calculated as shown in Equation 4 below.

[0070]

[0071] Here, CA 1,2 is the distance between the positive and negative poles of adjacent unit cells C1 and C2.

[0072] As such, according to the present invention, in a stack process for forming an electrode assembly by stacking unit cells, the position of the electrode, particularly the cathode, of a unit cell transported by a conveyor is measured using an LWIR (long-wave infrared) optical system, and the alignment value of the unit cell is corrected using this and positioned on a stacking table. Then, during the stacking process on the stacking table, the distance between the anode and cathode of two adjacent unit cells is measured to calculate the degree of alignment between the electrodes of the unit cells based on the cathode, thereby enabling real-time overhang inspection.

[0073] Although preferred embodiments of the present invention have been described above, the present invention is not limited to the specific embodiments described above. That is, those skilled in the art to which the present invention pertains can make numerous changes and modifications to the present invention without departing from the spirit and scope of the appended claims, and all such appropriate changes and modifications and equivalents should be deemed to fall within the scope of the present invention. Explanation of the symbols

[0074] 10. LWIR Vision Unit 20. Alignment Vision Unit 30. Correction Transfer Unit 40. Stack Vision Unit 50, C1, C2 : Unit cell 60. Conveyor 70. Stackable Table

Claims

Claim 1 An LWIR vision unit installed near a conveyor through which a unit cell is transported, which measures the position of a cathode equipped in the unit cell by irradiating and photographing each of the four corner portions of the unit cell with long-wavelength infrared (LWIR); an alignment vision unit installed near the conveyor so as to be positioned behind the LWIR vision unit on the movement path of the unit cell, which receives cathode position data measured by the LWIR vision unit, calculates the cell center position relative to the cathode using the received cathode position data, and calculates an alignment correction value; and a correction transport unit that receives the alignment correction value from the alignment vision unit, transports the unit cell by the amount of the received alignment correction value, and stacks it on a stacking table. The electrode alignment inspection device of a unit cell comprises: a stack vision unit installed near the stacking table, measuring the anode position of the stacked unit cell, receiving cathode position data from the alignment vision unit, and using the measured and received anode position data and cathode position data to measure the distance between the anode and cathode (or cathode and anode) of two adjacent unit cells and calculate the degree of alignment between the electrodes of the unit cells based on the cathode; wherein the stack vision unit calculates the distance (CA 1, 2) between the anode and cathode of two adjacent unit cells (C1, C2) as shown in the following mathematical formula. Here, AC represents the distance between the anode and the cathode within a single unit cell, and C-Pos(Position) represents the position of the anode. Claim 2 An electrode alignment inspection device for a unit cell according to claim 1, wherein the LWIR vision unit measures a point located at a certain distance along the X-axis and Y-axis from the corner point of each corner of the unit cell to measure a total of 8 cathode positions (A, B, C, D, E, F, G, H). Claim 3 In claim 2, the alignment vision unit measures the four corner points (F1(x1,y1), F2(x2,y2), F3(x3,y3), F4(x4,y4)) of each unit cell using the cathode positions (A, B, C, D, E, F, G, H) received from the LWIR vision, and then the cell center position (F) relative to the cathode x , F y , F θ A unit cell electrode alignment inspection device characterized by calculating ) as per the following mathematical formula. Here, F1(x1,y1) is an extension of and The intersection point of the extension line, F2(x2,y2), is extension and The intersection point of the extension line, F3(x3,y3), is an extension of and The intersection point of the extension line, F4(x4,y4), is an extension of and The intersection point of the extension of. Claim 4 In claim 3, the alignment vision unit is the rotation center (R(R) of the arm of the transfer part of the correction transfer unit. x , R y Center of the unit cell (F) based on )) x , F y The center of the unit cell after rotating ) by θ (F'(F' x , F' y Calculate )) as shown in the following mathematical formula, and Next, the center of the unit cell after rotation obtained by the above mathematical formula (F'(F' x , F' y )) Stack center position (S x , S y , S θ A unit cell electrode alignment inspection device characterized in that the final alignment correction value transferred by the transfer unit based on the position where the transfer unit moves, i.e., the stack center position, is as follows: Here, θ is S, the tilted angle of the stack center. θ F, which is the tilted angle of the center of the unit cell. θ The value minus . Claim 5 delete

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