Secondary battery sealing portion thickness measuring method and secondary battery sealing portion thickness measuring device

Abstract

A secondary battery sealing portion thickness measuring method of the present invention comprises: a first thickness measuring step for, by using a pair of distance measuring sensors, measuring the thickness of a verification sample which is formed from the same material as a pouch of a secondary battery; a second thickness measuring step for measuring the thickness of a sealing portion of the secondary battery by using the pair of distance measuring sensors; a deviation calculation step for calculating a deviation by using the difference between the measured thickness of the verification sample and a prestored reference thickness of the verification sample; and a thickness correction step for correcting the thickness measurement value of the sealing portion of the secondary battery by using the calculated deviation.

Description

Method for measuring thickness of secondary battery sealing part and device for measuring thickness of secondary battery sealing part

[0001] The present invention relates to a method for measuring the thickness of a secondary battery sealing part and a device for measuring the thickness of a secondary battery sealing part. More specifically, the invention relates to a method and device for measuring the thickness of a secondary battery sealing part that can accurately measure the thickness of the sealing part by minimizing measurement errors caused by the refraction of a laser beam through the correction of measurement deviations due to temperature changes of the sensor using a verification sample made of the same material as the actual secondary battery.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2025-0013332 dated February 3, 2025, and all contents disclosed in the document of said Korean patent application are incorporated herein as part of this specification.

[0003] The importance of the secondary battery industry is increasing day by day, driven by the rapid growth of the electric vehicle and energy storage system (ESS) markets. In particular, pouch-type secondary batteries are gaining prominence due to their high energy density and excellent heat dissipation characteristics, making product quality control increasingly critical. Among these factors, the quality of the sealing portion of pouch-type batteries is a key element that directly affects battery safety and lifespan.

[0004] Figures 1 and 2 are front views schematically showing the appearance of a general secondary battery sealing thickness measuring device (10).

[0005] In the inspection of the sealing part of a pouch-type battery, it is very important to precisely measure the thickness and width of the seal. Currently, an automatic inspection method using an upper sensor (11) and a lower sensor (12) installed on a measuring device (10) is widely used for inspecting the sealing part of a pouch-type battery. This method has the advantage of enabling non-contact measurement, which can prevent product damage, and allows for full inspection.

[0006] Referring to FIGS. 1 and 2, the measuring device (10) is installed such that an upper sensor (11) and a lower sensor (12) face each other, and the thickness of the sealing part (1) is measured as a pouch-type battery (2) is transported between them by a transport device (not shown). The sensors measure the height of the object to be measured using a laser beam (L) and calculate the thickness of the sealing part (1) through the difference in measurement values ​​between the upper sensor (11) and the lower sensor (12).

[0007] FIG. 3 is a plan view schematically showing the appearance of a metal specimen (20) that is generally used for deviation correction.

[0008] Referring to FIG. 3, the current measurement system can correct existing measurement values ​​using the measured thickness and temperature values ​​of the metal specimen (20) using the upper sensor (11) and the lower sensor (12). Specifically, a method is used to correct the measurement value of the actual pouch-type battery (2) using the deviation between the measured value of the metal specimen (20) and the actual thickness value of the metal specimen. The metal specimen (20) is mounted on a mounting base (14) and can be moved into the space between the upper sensor (11) and the lower sensor (12) by the driving unit (16).

[0009] However, this measurement method has the following problems.

[0010] First, the sensor (11, 12) has a characteristic in that the measured value changes according to the temperature change. Specifically, the sensor experiences a change in the measured value of about 4 μm per 1°C change in temperature. To solve this problem, the deviation is corrected using a metal specimen (20), but this is not a perfect solution.

[0011] Second, an error of about 36 μm to 37 μm occurs due to the refraction of the laser beam (L) in the polymer (PET; Polyethylene terephthalate) layer coated on the surface of the pouch-type battery (2). This is a problem that cannot be completely solved even by deviation correction using a metal specimen (20). In particular, since the metal specimen (20) and the actual pouch-type battery (2) have different materials, the degree of change in the measured value due to temperature change is different from each other, making accurate correction difficult.

[0012] Third, in order to check the performance of the sensors (11, 12), there is the inconvenience of having to stop production and mount the actual pouch-type battery (2) on the measuring device (10) to measure it. This can lead to a decrease in productivity.

[0013] Due to these issues, quality control of the sealing part of pouch-type batteries is difficult, which can have a negative impact on product reliability and production efficiency.

[0014] Therefore, there is a need to develop new technology that can effectively correct measurement errors caused by temperature changes in the sensor and continuously monitor sensor performance without interrupting production.

[0015] The present invention aims to solve the problems that occur in the conventional process of measuring the thickness of a secondary battery sealing part.

[0016] The purpose of the present invention is to provide a method and device for measuring the thickness of a secondary battery sealing part that can accurately measure the thickness of the sealing part by correcting the measurement deviation caused by the temperature change of the sensor through one embodiment of the invention.

[0017] Specifically, through one embodiment of the present invention, the purpose is to provide a method and device for measuring the thickness of a secondary battery sealing portion that can minimize measurement errors caused by laser beam refraction and accurately measure the thickness of the sealing portion by correcting measurement deviations due to temperature changes of the sensor using a verification sample made of the same material as the pouch of an actual secondary battery.

[0018] In addition, the present invention aims to provide a method and device for measuring the thickness of a secondary battery sealing portion, which, through an embodiment of the present invention, can check the performance of the sensor without stopping production and monitor the state of the sensor using a plurality of verification samples having different thicknesses.

[0019] In addition, the present invention aims to provide a more precise method and device for measuring the thickness of a secondary battery sealing portion by measuring the thickness of a sealing portion at different locations, such as an electrode-side sealing portion with protruding electrode leads and a non-electrode-side sealing portion without protruding electrode leads, through an embodiment of the present invention.

[0020] To achieve the aforementioned objective, according to one embodiment of the present invention, a method for measuring the thickness of a sealing portion of a secondary battery pouch is provided, comprising: a first thickness measurement step of measuring the thickness of a verification sample of the same material as the pouch of the secondary battery using a pair of distance measuring sensors; a second thickness measurement step of measuring the thickness of the sealing portion of the secondary battery using the pair of distance measuring sensors; a deviation calculation step of calculating a deviation using the difference between the measured thickness of the verification sample and a reference thickness of the verification sample stored in advance; and a thickness correction step of correcting the measured thickness of the sealing portion of the secondary battery using the calculated deviation.

[0021] In the first thickness measurement step, the verification sample is placed between a pair of distance measuring sensors, and before measuring the thickness of the verification sample, the driving unit moves the mounting plate on which the verification sample is mounted into the field of view of the pair of distance measuring sensors; and after measuring the thickness of the verification sample, the driving unit returns the mounting plate to its original position.

[0022] In the first thickness measurement step above, the thickness of a plurality of samples having different thicknesses can be measured.

[0023] The above verification sample may be cut from the sealing portion of the secondary battery.

[0024] The above verification sample may include a sealing portion formed by overlapping pouch films and heat-sealing the overlapping area.

[0025] Before the first thickness measurement step, the cell preparation step of preparing a verification sample made of the same material as the secondary battery; and the cell mounting step of mounting the verification sample on the mounting base are further included, wherein the cell preparation step of preparing the verification sample may provide a plurality of verification samples having different thicknesses.

[0026] The cell preparation step above may prepare at least one of a first verification sample comprising an electrode-side sealing portion in which the positive lead is exposed; a second verification sample comprising an electrode-side sealing portion in which the negative lead is exposed; and a third verification sample comprising a non-electrode-side sealing portion in which the positive lead and the negative lead are not exposed.

[0027] The above deviation calculation step may include: a step of calculating the difference between the thickness measured for each of the plurality of verification samples and the preset reference thickness of each verification sample; a step of calculating the average value of the calculated differences and setting it as the deviation; and a step of correcting the thickness measurement value of the sealing portion of the secondary battery using the set deviation.

[0028] It may further include a performance check step for checking the performance of a pair of distance measuring sensors based on the thickness values ​​of each of the plurality of verification samples measured in the first thickness measurement step.

[0029] The above performance check step may include: a step of comparing the difference between each thickness measured for the plurality of verification samples and a preset reference thickness; a step of determining that there is an abnormality in a verification sample if only the difference of some of the plurality of verification samples deviates from the reference range; and a step of determining that there is an abnormality in the pair of distance measuring sensors if the difference of all of the plurality of verification samples deviates from the reference range.

[0030] To achieve the aforementioned purpose, according to another embodiment of the present invention, a secondary battery sealing thickness measuring device is provided, comprising: a driving unit having a mounting base on which a verification sample made of the same material as the secondary battery is mounted; a pair of distance measuring sensors arranged to measure the thickness of the sealing part of the secondary battery or the verification sample, respectively; and a control unit arranged to calculate a deviation between the thickness of the verification sample measured by the pair of distance measuring sensors and a preset reference thickness, and to correct the measured value of the thickness of the sealing part of the secondary battery using the calculated deviation.

[0031] The above verification sample includes a sealing portion heat-fused with a pouch film in a stacked state, and a pair of distance measuring sensors may include an upper distance measuring sensor located on the upper part of the sealing portion or the verification sample and a lower distance measuring sensor located on the lower part of the sealing portion or the verification sample.

[0032] The above verification samples are a plurality of samples, and the plurality of verification samples may include at least one of a first verification sample comprising an electrode-side sealing portion in which an anode lead is exposed; a second verification sample comprising an electrode-side sealing portion in which a cathode lead is exposed; and a third verification sample comprising a non-electrode-side sealing portion in which the anode lead and the cathode lead are not exposed.

[0033] The control unit may be configured to calculate the difference between the thickness measured for each of the plurality of verification samples and the preset reference thickness of each verification sample, calculate the average value of the calculated differences and set it as a deviation, and correct the thickness measurement value of the sealing portion of the secondary battery using the set deviation.

[0034] The control unit may be configured to compare the difference between each thickness measured for the plurality of verification samples and a preset reference thickness, and to determine an abnormality in the verification samples if only some of the differences among the plurality of verification samples fall outside the reference range, and to determine an abnormality in the pair of distance measuring sensors if the differences of all the plurality of verification samples fall outside the reference range.

[0035] The above driving unit may be configured to alternately repeat moving the mounting bracket on which the verification sample is mounted so that it comes within the field of view of the pair of distance measuring sensors, or returning it to its original position.

[0036] As described above, the method and device for measuring the thickness of a secondary battery sealing portion according to one embodiment of the present invention have the following effects.

[0037] By using a verification sample made of the same material as the actual secondary battery pouch to correct measurement deviations caused by temperature changes in the sensor, measurement errors caused by the refraction of the laser beam can be minimized, thereby enabling accurate measurement of the thickness of the sealing portion.

[0038] Accordingly, errors caused by laser refraction that occurred when using conventional metal specimens can be eliminated. In addition, since sensor performance can be checked without stopping production, the floating time per lane required in conventional technology becomes unnecessary, thereby significantly improving productivity.

[0039] In addition, the status of the sensor can be monitored using multiple verification samples with different thicknesses. This allows for accurate determination of whether the cause of an anomaly in measurement values ​​lies in the verification samples or the measurement sensor, thereby enabling prompt and precise action.

[0040] In addition, to accurately measure sealing portions of various thicknesses, a plurality of verification samples corresponding to the electrode side where the electrode lead is protruding or the non-electrode side where the electrode lead is not protruding are provided, thereby enabling more precise measurements from the thickness values ​​of the sealing portions that differ by location.

[0041] In addition, the reliability of the measurement can be improved by using multiple verification samples.

[0042] Figures 1 and 2 are front views schematically showing the appearance of a general secondary battery sealing thickness measuring device.

[0043] Figure 3 is a plan view schematically showing the appearance of a metal specimen generally used for deviation correction.

[0044] FIG. 4 is a flowchart showing the steps of a method for measuring the thickness of a secondary battery sealing portion according to one embodiment of the present invention.

[0045] FIG. 5 is a conceptual block diagram showing the configurations of a secondary battery sealing thickness measuring device according to one embodiment of the present invention.

[0046] FIGS. 6 and 7 are front views schematically showing the appearance of a secondary battery sealing thickness measuring device according to one embodiment of the present invention.

[0047] FIG. 8 is a partial enlarged view schematically showing a part of the configuration of a secondary battery sealing thickness measuring device according to one embodiment of the present invention.

[0048] FIG. 9 is a plan view schematically showing the appearance of verification samples used in the method for measuring the thickness of a secondary battery sealing portion according to one embodiment of the present invention.

[0049] FIG. 10 is a schematic plan view showing the appearance of a secondary battery for preparing verification samples used in a method for measuring the thickness of a secondary battery sealing portion according to one embodiment of the present invention.

[0050] Hereinafter, a method (100) for measuring the thickness of a secondary battery sealing part and a device (200) for measuring the thickness of a secondary battery sealing part according to one embodiment of the present invention will be described in detail with reference to the attached drawings.

[0051] Additionally, identical or corresponding components are assigned the same or similar reference numbers regardless of drawing symbols, and redundant descriptions thereof are omitted; furthermore, for the convenience of explanation, the size and shape of each illustrated component may be exaggerated or reduced.

[0052] FIG. 4 is a flowchart showing the steps of a method (100) for measuring the thickness of a secondary battery sealing portion according to one embodiment of the present invention. FIG. 5 is a block diagram conceptually showing the configurations of a device (200) for measuring the thickness of a secondary battery sealing portion according to one embodiment of the present invention.

[0053] Referring to FIGS. 4 and 5, a method (100) for measuring the thickness of a secondary battery sealing portion related to one embodiment of the present invention includes a first thickness measurement step (M03), a second thickness measurement step (M04), a deviation calculation step (M05), and a thickness correction step (M06).

[0054] In addition, the method (100) for measuring the thickness of a secondary battery sealing portion related to one embodiment of the present invention can be performed using a secondary battery sealing portion thickness measuring device (200) related to one embodiment of the present invention.

[0055] FIGS. 6 and FIGS. 7 are front views schematically showing the appearance of a secondary battery sealing part thickness measuring device (200) according to one embodiment of the present invention.

[0056] A secondary battery sealing thickness measuring device (200) related to one embodiment of the present invention includes a driving unit (210), a pair of distance measuring sensors (221, 222), and a control unit (240).

[0057] FIG. 8 is a partial enlarged view schematically showing a part configuration of a secondary battery sealing part thickness measuring device (200) according to one embodiment of the present invention, FIG. 9 is a plan view schematically showing the appearance of verification samples (250) used in a secondary battery sealing part thickness measuring method according to one embodiment of the present invention, and FIG. 10 is a plan view schematically showing the appearance of a secondary battery (300) for preparing verification samples (250) used in a secondary battery sealing part thickness measuring method (100) according to one embodiment of the present invention.

[0058] For reference, as shown in FIG. 6, the Z-axis direction is the direction of gravity, the Y-axis direction is the direction of transport of the secondary battery (300), and the X-axis direction is the direction of transport (entry / retraction) of the mounting stand (212). For example, the direction of transport of the secondary battery (300) and the direction of transport of the mounting stand (212) can be orthogonal.

[0059] Specifically, the first thickness measurement step (M03) is a step of measuring the thickness of a verification sample (250) made of the same material as the pouch (360) of the secondary battery (300) using a pair of distance measuring sensors (221, 222). The verification sample (250) may be placed on a mounting base (212). When measuring the thickness, the verification sample (250) is placed between the pair of distance measuring sensors (221, 222), and the driving unit (210) is configured to move the mounting base (212) into the field of view of the pair of distance measuring sensors (221, 222) before measuring the thickness of the verification sample (250). Additionally, the driving unit (210) may return the mounting base (212) to its original position after the thickness measurement of the verification sample (250) is completed.

[0060] The second thickness measurement step (M04) is a step of measuring the thickness of the actual sealing portion (320) of the secondary battery (300) using a pair of distance measuring sensors (221, 222). At this time, the pair of distance measuring sensors (221, 222) can measure the thickness of the actual sealing portion (320) using a laser beam (L). In addition, the pouch (360) of the secondary battery (300) to be measured may be provided to accommodate an electrode assembly (318) and an electrolyte (not shown) inside. Referring to FIGS. 6 and FIGS. 10, the actual sealing portion (320) may include one or more of the electrode-side sealing portions (311, 312) and non-electrode-side sealing portions (322, 324) of the secondary battery (300). For example, in the second thickness measurement step, only the thickness of one or more of the electrode-side sealing portions (311, 312) and non-electrode-side sealing portions (322, 324) may be measured individually. As another example, in the second thickness measurement step, while transporting the secondary battery (300) between a pair of distance measuring sensors (221, 222), the thickness of the electrode-side sealing portions (311, 312) and non-electrode-side sealing portions (322, 324) may be measured continuously in a scanning manner.

[0061] For example, after the first thickness measurement step, and after the second thickness measurement step, the first thickness measurement step may be performed, and after the second thickness measurement step, the first thickness measurement step may be performed.

[0062] Here, a pair of distance measuring sensors (221, 222) includes two distance measuring sensors (221, 222) spaced apart with the actual sealing part (330) and the verification sample (250) in between, respectively, during the first thickness measurement step and the second thickness measurement step. During each thickness measurement step, the two spaced distance measuring sensors (221, 222) can measure the thickness by irradiating a laser beam (L) toward both sides of the actual sealing part (330) and the verification sample (250), respectively. This arrangement structure enables accurate thickness measurement by measuring the distance from both sides of the object to be measured.

[0063] A pair of distance measuring sensors (221, 222) includes an upper distance measuring sensor (221) positioned above the actual sealing part (320) and the verification sample (250) during the first thickness measurement step and the second thickness measurement step, and a lower distance measuring sensor (222) positioned below the actual sealing part (320) and the verification sample (250). Each distance measuring sensor (221, 222) is equipped with a light-emitting part (not shown) that emits a laser beam (L) and a light-receiving part (not shown) that receives the reflected laser beam (L). Specifically, the light-emitting part of the upper distance measuring sensor (221) emits a laser beam (L) toward the upper surface of the verification sample (250), and the light-receiving part of the upper distance measuring sensor (221) receives the laser beam (L) reflected from the upper surface to measure the distance between the upper distance measuring sensor (221) and the upper surface of the verification sample (250). Likewise, the light-emitting part of the lower distance measuring sensor (222) irradiates a laser beam (L) toward the lower surface of the verification sample (250), and the light-receiving part of the lower distance measuring sensor (222) receives the laser beam (L) reflected from the lower surface to measure the distance between the lower distance measuring sensor (222) and the lower surface of the verification sample (250).

[0064] The control unit (240) can calculate the thickness of the verification sample by calculating the value obtained by subtracting the distance to the upper surface and the distance to the lower surface, respectively, from the reference distance between a pair of distance measuring sensors (221, 222).

[0065] The deviation calculation step (M05) is a step of calculating the deviation using the difference between the thickness of the measured verification sample (250) and the previously stored reference thickness. Here, the previously stored reference thickness may be the value of the thickness of the verification sample (250) measured by a pair of distance measuring sensors (221, 222) when the reference temperature is at.

[0066] The thickness correction step (M06) is a step of correcting the actual thickness measurement value of the sealing part (320) of the secondary battery (300) using the calculated deviation. At this time, the control unit (240) can correct the actual thickness measurement value of the sealing part (320) measured in the second thickness measurement step (M04) using the deviation set in the deviation calculation step (M05).

[0067] Accordingly, the present invention can minimize measurement errors caused by the refraction of the laser beam (L) and improve the accuracy of thickness measurement by correcting deviations using a verification sample (250) made of the same material and process as the actual secondary battery (300) through this configuration.

[0068] Meanwhile, the method (100) for measuring the thickness of a secondary battery sealing portion of the present invention may further include a cell preparation step (M01) and a cell mounting step (M02).

[0069] The cell preparation step (M01) is a step of preparing a verification sample (250) of the same material as the secondary battery (300). The verification sample (250) can be prepared in two ways. First, the verification sample (250) can be prepared by cutting from the actual sealing portion (320) of the pouch (360) of the actual secondary battery (300). This is the method to obtain the most accurate reference value. Second, the sealing portion (253) of the sample can be formed by overlapping and heat-fusing pouch films used in the production of the pouch (360) of the secondary battery (300).

[0070] Here, the pouch film may include an outer layer, an intermediate layer, and an inner layer. For example, the outer layer may include a PET (polyethylene terephthalate) material, the intermediate layer may include an aluminum foil, and the inner layer may include a PP (polypropylene) or modified PP material. At this time, the sealing portion (253) of the sample must be formed under the same process conditions as the actual sealing portion (320) of the secondary battery (300).

[0071] In the cell preparation step (M01), a plurality of verification samples (250) having different thicknesses may be prepared. Specifically, the plurality of verification samples (250) may include a first verification sample comprising an electrode-side sealing portion (311) in which the positive lead (331) is exposed. That is, the first verification sample may be a part of the sealing portion formed on the outer periphery where the positive lead (331) is located. The plurality of verification samples (250) may include a second verification sample comprising an electrode-side sealing portion (312) in which the negative lead (333) is exposed. That is, the second verification sample may be a part of the sealing portion formed on the outer periphery where the negative lead (333) is located. The plurality of verification samples (250) may include a third verification sample comprising a non-electrode-side sealing portion (322, 324). In the cell preparation step (M01), the electrode side sealing portions (311, 312) can be prepared by cutting out the sealing portions that do not overlap with the positive lead (331) or the negative lead (333).

[0072] Additionally, the thickness of the sealing portions at different locations of the secondary battery (300) may vary. For example, the thickness of the electrode-side sealing portion (311) near the positive electrode lead (331) may be 900 μm to 960 μm, the thickness of the electrode-side sealing portion (312) near the negative electrode lead (333) may be 620 μm to 680 μm, and the thickness of the non-electrode-side sealing portions (322, 324) may be 230 μm to 300 μm. This range of sealing portion thicknesses is an optimized value that can minimize the overall volume of the secondary battery while ensuring airtightness and mechanical strength of the secondary battery.

[0073] The cell mounting step (M02) is a step of mounting a prepared verification sample (250) onto a mounting base (212). The mounting base (212) may include a first mounting member (214) and a second mounting member (215). The first mounting member (214) is provided to secure one end of the verification sample (250) onto the mounting base (212). The second mounting member (215) is provided to secure the other end of the verification sample (250) onto the mounting base (212).

[0074] Additionally, the deviation calculation step (M05) may include the step of calculating the difference between the thickness measured for each of the plurality of verification samples (250) and the pre-stored reference thickness of each verification sample (250), the step of calculating the average value of the calculated differences and setting it as the deviation, and the step of correcting the actual sealing portion (320) thickness measurement value of the secondary battery (300) using the set deviation.

[0075] Specifically, the control unit (240) can calculate a value obtained by subtracting the reference thickness of the verification sample (250) from the measured thickness for each verification sample (250), and calculate the arithmetic mean of the multiple difference values ​​thus calculated to set as the final deviation value. For example, if the measured thickness of the first verification sample is 930 μm and the reference thickness is 920 μm, the deviation value may be 10 μm.

[0076] Meanwhile, the method (100) for measuring the thickness of a secondary battery sealing part of the present invention may further include a performance inspection step for checking the performance of a pair of distance measuring sensors (221, 222) based on the thickness values ​​of each of the plurality of verification samples (250) measured in the first thickness measurement step (M03).

[0077] In the performance check stage, the difference between the thickness measured for each of the multiple verification samples (250) and the preset reference thickness is compared, and if only some of the differences among the multiple verification samples (250) fall outside the reference range, it is determined that there is an abnormality in the verification sample, and if all of the differences among the multiple verification samples (250) fall outside the reference range, it is determined that there is an abnormality in the pair of distance measuring sensors (221, 222).

[0078] Additionally, if only some of the multiple verification samples (250) fall outside the reference range, it is determined that the problem is due to deformation or damage to the verification samples, and the verification samples are replaced. On the other hand, if the measured values ​​of all verification samples fall outside the reference range, it is determined that the sensor needs calibration, and sensor calibration can be performed.

[0079] Accordingly, the present invention can improve the reliability of the measurement system by checking the state of the sensor based on the thickness of the verification sample (250) through this configuration.

[0080] Hereinafter, the configuration of a secondary battery sealing part thickness measuring device (200) according to one embodiment of the present invention will be described in more detail.

[0081] Meanwhile, referring again to FIGS. 4 to 9, a secondary battery sealing thickness measuring device (200) according to one embodiment of the present invention includes a driving unit (210), a pair of distance measuring sensors (221, 222), and a control unit (240).

[0082] The driving unit (210) is provided with a mounting base (212) on which a verification sample (250) made of the same material as the secondary battery (300) is mounted. That is, the driving unit (210) is configured to alternately move the mounting base (212) on which the verification sample (250) is mounted so that it comes within the field of view of a pair of distance measuring sensors (221, 222) or return it to its original position. For example, the driving unit (210) may include a servo motor and a linear guide to precisely control the position of the mounting base (212).

[0083] The mounting base (212) may include a first mounting member (214) and a second mounting member (215). The first mounting member (214) is provided to secure one end of the verification sample (250) onto the mounting base (212). The second mounting member (215) is provided to secure the other end of the verification sample (250) onto the mounting base (212). As shown in FIG. 8, the verification sample (250) is firmly secured between the first mounting member (214) and the second mounting member (215), and the sealing portion (253) of the sample is provided to be accurately positioned on the measurement path of the laser beam (L).

[0084] A pair of distance measuring sensors (221, 222) includes an upper distance measuring sensor (221) and a lower distance measuring sensor (222). A pair of distance measuring sensors (221, 222) are configured to measure the thickness of the sealing portion (253) of the sample of the verification sample (250) or the actual sealing portion (320) of the secondary battery (300).

[0085] Referring to FIGS. 6 and 7, a pair of distance measuring sensors (221, 222) can measure the thickness of the actual sealing portion (320) of a secondary battery (300) being produced using a laser beam (L). Additionally, a pair of distance measuring sensors (221, 222) can measure the thickness of the sealing portion (253) of a sample of a verification sample (250) for thickness correction. For example, the upper distance measuring sensor (221) irradiates a laser beam (L) from the top, and the lower distance measuring sensor (222) irradiates a laser beam (L) from the bottom, and the thickness of the object to be measured can be measured by comparing the distance values ​​measured by each of the pair of distance measuring sensors (221, 222) with the distance values ​​when there is no object to be measured.

[0086] The control unit (240) can receive thickness information of a verification sample (250) measured by a pair of distance measuring sensors (221, 222). The control unit (240) calculates the deviation between the thickness of the verification sample (250) measured by the pair of distance measuring sensors (221, 222) and a pre-stored reference thickness, and uses the calculated deviation to correct the actual thickness measurement value of the sealing part (320) of the secondary battery (300). The control unit (240) can perform measurements at regular intervals and monitor environmental conditions to ensure measurement reliability.

[0087] Meanwhile, the control unit (240) may be configured to include a processing device such as a microchip. Specifically, the control unit (240) may be implemented as a microcontroller unit (MCU) including a central processing unit (CPU), random access memory (RAM), read-only memory (ROM), etc. Additionally, the control unit (240) may incorporate a high-speed analog-to-digital converter (ADC) and a digital-to-analog converter (DAC) to enable fast processing of analog sensor signals and precise motor control.

[0088] As shown in FIG. 10, the secondary battery (300) includes an electrode-side sealing portion (311) with a positive lead (331) exposed, an electrode-side sealing portion (312) with a negative lead (333) exposed, and non-electrode-side sealing portions (322, 324). The sealing portions (311, 312, 320) may have different thicknesses. At this time, a plurality of verification samples (250) may be provided to correspond to the actual thicknesses of the sealing portions (311, 312, 320), respectively.

[0089] Referring to FIGS. 8 and 9, a plurality of verification samples (250) may be provided. The plurality of verification samples (250) may include a first verification sample comprising an electrode-side sealing portion (311) where a positive lead (331) is located, a second verification sample comprising an electrode-side sealing portion (312) where a negative lead (333) is located, and a third verification sample comprising non-electrode-side sealing portions (322, 324).

[0090] Specifically, a plurality of verification samples (250) may be provided to have different thicknesses in order to accurately measure the thickness of the electrode-side sealing portions (311, 312) and non-electrode-side sealing portions (322, 324) of the secondary battery (300). For example, the electrode-side sealing portion (311) where the positive lead (331) is located may have a thickness of 680 μm, and the non-electrode-side sealing portions (322, 324) may have a thickness of 230 μm to 300 μm.

[0091] The above control unit (240) is configured to calculate the difference between the thickness measured for each of the plurality of verification samples (250) and the pre-stored reference thickness of each verification sample (250), calculate the average value of the calculated differences and set it as a deviation, and use the set deviation to correct the actual thickness measurement value of the sealing part (320) of the secondary battery (300).

[0092] Accordingly, the present invention can correct measurement errors caused by changes in sensor temperature while minimizing measurement errors caused by refraction of the laser beam (L) through this configuration, thereby enabling accurate measurement of the thickness of the actual sealing portion (320) of the secondary battery (300).

[0093] Specifically, the control unit (240) is configured to determine the state of the sensor by comparing the difference between the thickness measured for each of the multiple verification samples (250) and a pre-stored reference thickness. For example, the control unit (240) is configured to determine that there is an abnormality in the verification sample (250) if only some of the differences among the multiple verification samples (250) fall outside the reference range. That is, if only one of the multiple verification samples (250) falls outside the reference range, the control unit (240) determines that there is a problem with the verification sample (250) and can output a signal to replace the verification sample (250).

[0094] On the other hand, the control unit (240) is configured to determine that there is an abnormality in a pair of distance measuring sensors (221, 222) when the difference between all of the multiple verification samples (250) falls outside the reference range. For example, if the measurement values ​​of all verification samples (250) fall outside the reference range, the control unit (240) may determine that calibration of the pair of distance measuring sensors (221, 222) is required and output a sensor check signal.

[0095] Therefore, the present invention can accurately determine whether the cause of an abnormality in the measurement value is in the verification sample (250) or the measurement sensor (221, 222) when an abnormality occurs due to this configuration, thereby enabling quick and accurate action.

[0096] Meanwhile, the driving unit (210) is configured to alternately move the mounting stand (212) on which the verification sample (250) is mounted so that it comes within the field of view of a pair of distance measuring sensors (221, 222) or return it to its original position. Specifically, the driving unit (210) can move the mounting stand (212) in the forward and backward directions using the driving force of a servo motor.

[0097] For example, the driving unit (210) can repeat the operation of moving the mounting base (212) into the field of view of a pair of distance measuring sensors (221, 222) to measure the thickness of the verification sample (250) and then returning the mounting base (212) to its original position. At this time, the movement speed and measurement cycle of the mounting base (212) can be controlled by the control unit (240).

[0098] Accordingly, the present invention can continuously monitor the state of the sensor by periodically measuring the thickness of the verification sample (250) through this configuration, thereby improving the reliability of the thickness measurement of the actual sealing part (320) of the secondary battery (300).

[0099] The preferred embodiments of the present invention described above are disclosed for illustrative purposes only, and those skilled in the art with ordinary knowledge of the present invention will be able to make various modifications, changes, and additions within the spirit and scope of the present invention, and such modifications, changes, and additions should be considered to fall within the scope of the following claims.

[0100] According to the method and apparatus for measuring the thickness of a secondary battery sealing portion according to one embodiment of the present invention, the thickness of the sealing portion can be accurately measured by using a verification sample of the same material as the pouch of an actual secondary battery to correct the measurement deviation caused by the temperature change of the sensor.

Claims

1. A method for measuring the thickness of the sealing portion of a pouch of a secondary battery, A first thickness measurement step of measuring the thickness of a verification sample of the same material as the pouch of a secondary battery using a pair of distance measuring sensors; A second thickness measurement step of measuring the thickness of the sealing portion of the secondary battery using the above pair of distance measuring sensors; A deviation calculation step for calculating a deviation using the difference between the thickness of the verification sample measured above and the reference thickness of the verification sample stored in advance; and A method for measuring the thickness of a secondary battery sealing portion, characterized by including a thickness correction step of correcting the measured thickness value of the secondary battery sealing portion using the deviation calculated above.

2. In Paragraph 1, The first thickness measurement step is, The above verification sample is placed between a pair of distance measuring sensors, and Before measuring the thickness of the verification sample, the driving unit moves the mounting bracket on which the verification sample is mounted into the field of view of the pair of distance measuring sensors; and A method for measuring the thickness of a secondary battery sealing portion, characterized by including the step of, after measuring the thickness of the verification sample, the driving unit returning the mounting base to its original position.

3. In Paragraph 2, A method for measuring the thickness of a secondary battery sealing portion, characterized by measuring the thickness of a plurality of samples having different thicknesses in the first thickness measurement step.

4. In Paragraph 1, A method for measuring the thickness of a secondary battery sealing portion, characterized in that the above-mentioned verification sample is cut from the sealing portion of the secondary battery.

5. In Paragraph 1, A method for measuring the thickness of a secondary battery sealing portion, characterized in that the above-mentioned verification sample includes a sealing portion formed by stacking pouch films and heat-fusing them.

6. In Paragraph 3, Before the first thickness measurement step above, A cell preparation step for preparing a verification sample of the same material as the secondary battery; and The method further includes a cell mounting step of mounting the verification sample on the mounting stand; and The cell preparation step for preparing the above verification sample is, A method for measuring the thickness of a secondary battery sealing portion, characterized by preparing multiple verification samples having different thicknesses.

7. In Paragraph 6, The above cell preparation step is, A first verification sample including an electrode-side sealing portion with an exposed positive lead; A second verification sample comprising an electrode-side sealing portion with an exposed cathode lead; and A method for measuring the thickness of a secondary battery sealing portion, characterized by preparing at least one of a third verification sample comprising: a non-electrode side sealing portion in which the positive lead and the negative lead are not exposed.

8. In Paragraph 3, The above deviation calculation step is, A step of calculating the difference between the thickness measured for each of the plurality of verification samples and the preset reference thickness of each verification sample; A step of calculating the average value of the differences calculated above and setting it as the deviation; and A method for measuring the thickness of a secondary battery sealing portion, characterized by including the step of correcting the measured value of the thickness of the secondary battery sealing portion using the deviation set above.

9. In Paragraph 3, A method for measuring the thickness of a secondary battery sealing portion, characterized by further including a performance inspection step for checking the performance of a pair of distance measuring sensors based on the thickness values ​​of each of the plurality of verification samples measured in the first thickness measurement step.

10. In Paragraph 9, The above performance check step is, A step of comparing the difference between each thickness measured for the plurality of verification samples and a preset reference thickness; A step of determining an abnormality in a verification sample when only the difference of some of the above plurality of verification samples deviates from a reference range; and A method for measuring the thickness of a secondary battery sealing portion, characterized by including the step of determining an abnormality in the pair of distance measuring sensors when the difference between all of the plurality of verification samples exceeds a reference range.

11. A device for measuring the thickness of a sealing portion of a secondary battery, A driving unit equipped with a mounting bracket on which a verification sample made of the same material as the secondary battery is mounted; A pair of distance measuring sensors arranged to measure the thickness of each of the sealing portion of the secondary battery or the verification sample; and A secondary battery sealing part thickness measuring device characterized by including: a control unit configured to calculate a deviation between the thickness of the verification sample measured by the above-mentioned pair of distance measuring sensors and a preset reference thickness, and to correct the measured value of the sealing part thickness of the secondary battery using the calculated deviation.

12. In Paragraph 11, The above verification sample is, It includes a sealing portion heat-fused with pouch films in a stacked state, A secondary battery sealing thickness measuring device characterized by comprising a pair of distance measuring sensors including an upper distance measuring sensor located above the sealing part or the verification sample and a lower distance measuring sensor located below the sealing part or the verification sample.

13. In Paragraph 12, The above verification samples are multiple, and The above plurality of verification samples are, A first verification sample including an electrode-side sealing portion with an exposed positive lead; A second verification sample comprising an electrode-side sealing portion with an exposed cathode lead; and A secondary battery sealing thickness measuring device characterized by including at least one of a third verification sample comprising a non-electrode side sealing portion in which the positive lead and the negative lead are not exposed.

14. In Paragraph 13, The above control unit is, Calculate the difference between the thickness measured for each of the above plurality of verification samples and the preset reference thickness of each verification sample, and The average value of the differences calculated above is calculated and set as the deviation, A secondary battery sealing thickness measuring device characterized by being configured to correct the measured value of the secondary battery sealing thickness using the above-determined deviation.

15. In Paragraph 13, The above control unit is, By comparing the difference between the thickness of each of the plurality of verification samples and a preset reference thickness, if the difference of only some of the plurality of verification samples deviates from the reference range, it is determined that the verification sample is abnormal. A secondary battery sealing thickness measuring device characterized by being configured to determine an abnormality of the pair of distance measuring sensors when the difference between all of the above-mentioned multiple verification samples deviates from a reference range.

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