WO2022235032A1 - Non-destructive inspection method for internal crack in pouch-type secondary battery - Google Patents

Non-destructive inspection method for internal crack in pouch-type secondary battery Download PDF

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Publication number
WO2022235032A1
WO2022235032A1 PCT/KR2022/006240 KR2022006240W WO2022235032A1 WO 2022235032 A1 WO2022235032 A1 WO 2022235032A1 KR 2022006240 W KR2022006240 W KR 2022006240W WO 2022235032 A1 WO2022235032 A1 WO 2022235032A1
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Prior art keywords
signal
output signal
crack
difference value
inspection area
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PCT/KR2022/006240
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French (fr)
Korean (ko)
Inventor
최백영
김승곤
구상문
김정원
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주식회사 이너아이
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Publication of WO2022235032A1 publication Critical patent/WO2022235032A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4285—Testing apparatus
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
    • G01N27/82—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws
    • G01N27/90—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws using eddy currents
    • G01N27/9046—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws using eddy currents by analysing electrical signals
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to a method for non-destructive inspection of internal cracks of a pouch-type secondary battery, and more particularly, to a non-destructive internal cracking inspection method of a pouch-type secondary battery capable of accurately detecting cracks in electrodes existing inside a sealed battery case It is about the inspection method.
  • Secondary batteries are in high demand for prismatic batteries and pouch-type batteries that are thin and have excellent occupancy space in terms of battery shape, and lithium secondary batteries with high energy density, discharge voltage, and output stability in terms of materials are in high demand. .
  • secondary batteries are classified according to the structure of the electrode assembly having a positive electrode/separator/negative electrode structure.
  • a jelly roll electrode assembly in which long sheet-shaped positive electrodes and negative electrodes are wound with a separator interposed therebetween, and a predetermined size
  • a stack-type electrode assembly in which a plurality of positive and negative electrodes cut in units of , sequentially stacked with a separator interposed therebetween.
  • a plurality of positive electrodes and negative electrodes cut into units of a predetermined size are sequentially stacked with a separator interposed therebetween to manufacture a stack type electrode assembly.
  • the electrode leads are heat-sealed and connected to the electrode tabs extending from the electrode assembly.
  • the electrode assembly is accommodated and mounted in a pouch-type case with a part of the electrode lead exposed to the outside.
  • the electrode leads are thermally fused together with the pouch-type case during the mounting process of the pouch-type case.
  • an electrolyte which is a liquid electrolyte, is injected into the pouch-type case, and then the pouch-type case is sealed to complete the manufacturing.
  • An object of the present invention for solving the above problems is to provide a non-destructive testing method for internal cracks in a pouch-type secondary battery capable of accurately detecting cracks in electrodes existing inside a sealed battery case after sealing is completed.
  • An internal crack non-destructive inspection method of a pouch-type secondary battery for solving the above-described problems, an input signal sending step of sending an input signal toward the inspection area; an output signal receiving step of receiving a modified output signal while the input signal passes through the inspection area; Comparing the output signal and a preset reference signal, the asymmetry of the first output signal region of the output signal disposed on one side and the second output signal region of the output signal disposed on the other side with respect to the center line of the reference signal a first signal pattern detection step of detecting a first difference value from the reference signal by Comparing the output signal and the reference signal, and detecting a second difference value between the center value of the reference signal located on the center line of the reference signal and the center value of the output signal located on the center line of the output signal detecting a second signal pattern; a first crack state determination step of determining whether a partial crack exists in the inspection area by comparing the first difference value with a preset first allowable error value; and a second crack state determination
  • the first signal pattern detection step generates a differential signal by differentiating the output signal, and based on the center line of the reference signal, one side Based on a difference value between a first maximum peak value of a first differential signal region of the differential signal disposed on the other side and a second maximum peak value of a second differential signal region of the differential signal disposed on the other side, the first difference value can be detected.
  • a first input signal having a first frequency and a second frequency different from the first frequency are performed before the step of transmitting the input signal. It may further include; an input signal synthesizing step of synthesizing two input signals.
  • the first output signal and the second input signal are performed after the step of receiving the output signal, and are transformed from the first input signal from the output signal
  • the method may further include an output signal decomposition step of decomposing the transformed second output signal from .
  • the first frequency may be used to determine whether a partial crack exists
  • the second frequency which is higher than the first frequency, is a complete crack.
  • the first signal pattern detection step may detect the first difference value by comparing the first output signal with the reference signal
  • the second signal pattern detection step includes the second output signal and the reference signal. can be compared to detect the second difference value.
  • the present invention by detecting and analyzing the pattern of the output signal with respect to the reference signal, it is possible to more quickly and accurately detect and determine the crack state due to the partial crack or the complete crack existing in the inspection area.
  • FIG. 1 is an exemplary view showing an internal crack non-destructive testing apparatus of a pouch-type secondary battery according to an embodiment of the present invention.
  • FIG. 2 is a partial cross-sectional view for explaining the operation of the internal crack non-destructive inspection apparatus of a pouch-type secondary battery according to an embodiment of the present invention.
  • FIG 3 is a partial plan view illustrating an inspection area in which an internal crack of a pouch-type secondary battery is formed according to an embodiment of the present invention.
  • FIG. 4 is a flowchart illustrating a method for non-destructive testing of internal cracks of a pouch-type secondary battery according to an embodiment of the present invention.
  • FIG. 5 is an exemplary view showing an output signal and a reference signal according to an embodiment of the present invention when there is no crack in the inspection area.
  • FIG. 6 is an exemplary view showing an output signal and a reference signal according to an embodiment of the present invention when there is a partial crack in the inspection area.
  • FIG. 7 is an exemplary view showing an output signal and a reference signal according to an embodiment of the present invention when there is a complete crack in the inspection area.
  • FIG. 8 is for explaining the first signal pattern detection step according to an embodiment of the present invention, and is an exemplary view showing an output signal (a diagram) and a differential signal (b diagram) when there is no crack in the inspection area.
  • FIG. 9 is an exemplary diagram illustrating an output signal (a diagram) and a differential signal (b diagram) when there is a partial crack in an inspection area, for explaining the first signal pattern detection step according to an embodiment of the present invention.
  • FIG. 10 is a flowchart illustrating a method for non-destructive testing of internal cracks of a pouch-type secondary battery according to another embodiment of the present invention.
  • FIG. 11 is an exemplary view for explaining an input signal synthesis step in the internal crack non-destructive inspection method of the pouch-type secondary battery shown in FIG. 10 .
  • FIG. 12 is an exemplary view for explaining an output signal decomposition step in the internal crack non-destructive inspection method of the pouch-type secondary battery shown in FIG. 10 .
  • FIG. 1 is an exemplary view showing an internal cracking non-destructive testing apparatus for a pouch-type secondary battery according to an embodiment of the present invention
  • FIG. 2 is an operation of the internal cracking non-destructive testing apparatus for a pouch-type secondary battery according to an embodiment of the present invention
  • 3 is a partial plan view illustrating an inspection area in which internal cracks of a pouch-type secondary battery according to an embodiment of the present invention are formed.
  • the internal crack non-destructive inspection method of the pouch-type secondary battery according to an embodiment of the present invention is present inside the case 14 in the manufacturing and assembly process of the pouch-type secondary battery 10.
  • the internal crack inspection apparatus of the pouch-type secondary battery is not limited to the stack-pouch-type secondary battery 10, and may be applied to all secondary batteries having various structures and shapes.
  • the stack-type electrode A stack-pouch type secondary battery 10 having an assembly 11 and a pouch type case 14 will be described as an example.
  • the internal crack non-destructive testing apparatus of a pouch-type secondary battery for performing the internal crack non-destructive testing method of the pouch-type secondary battery according to the present invention is a transmitter 110, a receiver 120 and A control unit 130 may be included.
  • the transmitter 110 may be disposed on one side of the secondary battery 10 which is an inspection object.
  • the transmitter 110 may transmit the input signal S1 toward the inspection area CA where cracks are expected inside the secondary battery 10 .
  • the input signal S1 may pass through the inspection area CA of the secondary battery 10, and in the process of passing through the inspection area CA, the input signal S1 is reflected according to the shape and material characteristics of the material located in the inspection area CA. , can be deformed by refraction, dispersion, diffraction, and the like.
  • the input signal S1 may be transmitted to the receiver 120 as it is, and the transmitter 110 ) and when the secondary battery 10 is present between the receiving unit 120, the input signal S1 passes through the secondary battery 10 and then is transformed into an output signal S3 different from the input signal S1, like this
  • the modified output signal S3 may be transmitted to the receiver 120 .
  • An eddy current type displacement sensor may be used as the transmitter 110 .
  • a primary magnetic field (corresponding to the first signal) is formed around the coil.
  • an eddy current that interferes with the primary magnetic field by generating an induced electromotive force in the inspection area CA due to electromagnetic induction will flow
  • a transformed secondary magnetic field (corresponding to the second signal) is formed in an area opposite to the transmitter 110 with the inspection area CA interposed therebetween while the primary magnetic field is canceled by the eddy current.
  • the receiver 120 may be disposed on the other side of the secondary battery 10 as an inspection object, and may be disposed to face the transmitter 110 with the secondary battery 10 interposed therebetween.
  • the receiving unit 120 may receive the modified output signal S3 while the input signal S1 transmitted from the transmitting unit 110 passes through the inspection area CA of the secondary battery 10 .
  • the receiver 120 may also use an eddy current type displacement sensor. That is, when an eddy current that interferes with the primary magnetic field flows due to an induced electromotive force generated in the inspection area CA of the secondary battery 10 by the primary magnetic field formed through the transmitter 110 , the secondary battery 10 inspection area The receiver 120 disposed in the region opposite to the transmitter 110 with the CA interposed therebetween may receive the output signal S3 corresponding to the transformed secondary magnetic field while the primary magnetic field is canceled by the eddy current. .
  • the space between the transmitter 110 and the inspection area CA of the secondary battery 10 may be a region where only the effect of the primary magnetic field (corresponding to the first signal) exists, and in this region, the magnetic field signal strength is strong.
  • the inspection area CA of the secondary battery 10 may be a region in which the primary magnetic field formed by the transmitter 110 and the secondary magnetic field formed by the eddy current are offset, and in this region, the magnetic field signal is rapidly reduced.
  • the space between the inspection area CA of the secondary battery 10 and the receiving unit 120 may be a region where only the effect of the secondary magnetic field (corresponding to the second signal) exists, and the strength of the magnetic field signal in this region is 1 It has a smaller strength than the secondary magnetic field.
  • the inspection area CA of the secondary battery 10 is a region where cracks are expected, and the inspection area CA is a bending region of the electrode tab 12 or the electrode tab 12 and the electrode lead ( 13) may be the welding area.
  • a crack may occur in the region of the electrode tab 12 .
  • the crack may be a bending region of the electrode tab 12 in which a plurality of electrode tabs 12 are connected to one electrode lead 13 or the electrode tab 12 and the electrode. It is intensively generated in the welding area of the lead (13).
  • the crack C existing in the bending region of the electrode tab 12 has a characteristic of extending in a direction crossing the bending direction of the electrode tab 12 , and welding of the electrode tab 12 and the electrode lead 13 .
  • the crack (C) existing in the region has a characteristic of extending in the longitudinal direction of the weld. That is, cracks C generated in the bending region of the electrode tab 12 and the welding region between the electrode tab 12 and the electrode lead 13 have similar directions.
  • FIG. 4 is a flowchart illustrating a method for non-destructive testing of internal cracks of a pouch-type secondary battery according to an embodiment of the present invention.
  • the method for non-destructive inspection of internal cracks of a pouch-type secondary battery includes an input signal sending step (S120), an output signal receiving step (S130), and a first signal pattern detecting step (S151). , a second signal pattern detection step (S152), a first crack state determination step (S161), and a second crack state determination step (S162).
  • the step of transmitting the input signal ( S120 ) may be a step of transmitting the input signal ( S1 ) toward the inspection area CA where the internal crack of the secondary battery 10 is expected. That is, the transmitter 110 may transmit the input signal S1 toward the examination area CA.
  • the output signal receiving step S130 may be a step of receiving the output signal S3 modified while the input signal S1 passes through the inspection area CA. That is, the receiver 120 may receive the modified output signal S3 while passing through the inspection area CA after being transmitted from the transmitter 110 .
  • the output signal S3 may be formed in a linear form for the entire section extending from one side to the other side of the inspection area CA.
  • the method for non-destructive inspection of internal cracks of a pouch-type secondary battery according to the present invention may further include a signal alignment step.
  • the signal alignment step may be a step in which the output signal S3 and the reference signal SS are overlapped and aligned. That is, in the signal alignment step, the output signal S3 crossing the center value S3c of the output signal S3 to the center line CL of the reference signal SS crossing the center value SSc of the reference signal SS. By matching the center line of , it is possible to align the output signal S3 with the reference signal SS.
  • the first signal pattern detection step S151 may be a step of detecting a first pattern of the output signal S3 by comparing the output signal S3 with a preset reference signal SS.
  • the first signal pattern detection step S151 may detect whether the output signal S3 maintains symmetry or asymmetry with respect to the center line CL of the reference signal SS. Accordingly, the first pattern means a symmetrical or asymmetrical pattern of the output signal S3.
  • FIG. 5 is an example showing an output signal and a reference signal according to an embodiment of the present invention when there is no crack in the inspection area.
  • the output signal S3 may be divided into a first output signal region S31 and a second output signal region S32 based on the center line CL of the reference signal SS. That is, the first output signal region S31 forms one side of the output signal S3 with respect to the center line CL of the reference signal SS, and the second output signal region S32 is the reference signal SS. The other side of the output signal S3 may be formed based on the center line CL.
  • the output signal S3 may match the reference signal SS, and the first output signal area ( S31) and the second output signal region S32 may be precisely symmetrical.
  • FIG. 6 is an example showing an output signal and a reference signal according to an embodiment of the present invention when there is a partial crack in the inspection area.
  • the output signal S3 is a first output signal area S31 and
  • the second output signal region S32 may be asymmetrical. That is, the first output signal region S31 may match the reference signal SS, while the second output signal region S32 may have a first difference value 21 from the reference signal SS.
  • the first signal pattern detection step S151 a symmetrical or asymmetrical pattern of the output signal S3 may be detected, and the first output signal region S31 based on the center line CL of the reference signal SS. And it is possible to accurately detect the degree of asymmetry of the output signal S3 through the first difference value 21 due to the asymmetry of the second output signal region S32. Accordingly, it is possible to detect whether the partial crack C1 exists in the inspection area CA.
  • the first difference value 21 in the first signal pattern detection step S151 may not be easily detected because the size is small.
  • the first signal pattern detection step S151 includes means for amplifying the magnitude of the first difference value 21 due to the symmetry or asymmetry of the output signal S3 and the reference signal SS. may include more.
  • FIG. 8 is for explaining the first signal pattern detection step according to another embodiment of the present invention, and is an example showing an output signal (a diagram) and a differential signal (b diagram) when there is no crack in the inspection area
  • FIG. 9 is for explaining the first signal pattern detection step according to an embodiment of the present invention, and is an example of an output signal (a diagram) and a differential signal (b diagram) when there is a partial crack in the inspection area.
  • a differential signal S4 is generated by differentiating the output signal S3, and the differential signal S4 thus generated is By using this, the first difference value 21 due to symmetry or asymmetry between the output signal S3 and the reference signal SS can be more accurately detected.
  • the differential signal S4 generated from the output signal S3 is a first differential signal region S41 and a second differential signal region S42 with respect to the center line CL of the reference signal SS.
  • the first differential signal region S41 forms one side of the differential signal S4 with respect to the center line CL of the reference signal SS
  • the second differential signal region S42 is the reference signal SS.
  • the other side of the differential signal S4 may be formed based on the center line CL.
  • the output signal S3 may coincide with the reference signal SS as in FIG. 8 (a), and the first differential as in FIG. 8 (b)
  • the output signal S3 is the first output signal area ( S31) and the second output signal region S32 may be asymmetric, and as shown in FIG. 9(b) , the first maximum peak value S411 of the first differential signal region S41 and the second differential signal region
  • the second maximum peak value S421 of S42 may have different values (height: H1>H2). That is, based on the difference value 21" between the first maximum peak value S411 of the first differential signal region S41 and the second maximum peak value S421 of the second differential signal region S42, the first difference The value 21 can be more accurately identified and detected.
  • the second signal pattern detection step S152 may be a step of detecting a second pattern of the output signal S3 by comparing the output signal S3 with a preset reference signal SS.
  • the second signal pattern detection step S152 is performed on the center value S3c of the reference signal SS positioned on the center line CL of the reference signal SS and the center line CL of the output signal S3. It is possible to detect an interval between the positioned output signal S3 and the center value S3c. Accordingly, the second pattern refers to the degree to which the center value S3c of the output signal S3 is offset from the center value SSc of the reference signal SS.
  • the output signal S3 may match the reference signal SS, and the center value SSc of the reference signal SS and The center value S3c of the output signal S3 may coincide with each other.
  • Figure 7 is an example showing the output signal and the reference signal according to an embodiment of the present invention when there is a complete crack in the inspection area.
  • the first output signal area S31 and the second output signal area S32 of the output signal S3 may be symmetrical.
  • the center value S3c of the output signal S3 and the center value SSc of the reference signal SS may be spaced apart from each other. That is, the center value S3c of the output signal S3 may be spaced apart from the center value SSc of the reference signal SS while having the second difference value 31 .
  • the degree of offset by which the output signal S3 is spaced apart from the reference signal SS can be detected, and the center value S3c of the output signal S3 and the reference signal ( A second difference value 31 between the center values SSc of SS) may be detected. Due to this, it is possible to detect whether the perfect crack C2 exists in the inspection area CA.
  • the first crack state determination step S161 may be a step of determining whether or not the secondary battery is defective due to the partial crack C1.
  • the first allowable error value 20 means a difference value between the reference signal SS and the first allowable error signal OKS1 .
  • the secondary battery may be determined to be a good product.
  • a partial crack C2 may exist in the inspection area CA, but in this case, the partial crack C2 is the quality of the secondary battery. It can be judged as a crack to the extent that it does not affect the battery, and therefore, even in this case, the secondary battery can be judged to be a good product.
  • the partial crack C2 existing in the inspection area CA affects the quality of the secondary battery. It may be judged to be a crack to the extent that it has reached, and therefore, in this case, the secondary battery may be judged to be a defective product.
  • the second crack state determination step ( S162 ) may be a step of determining whether the secondary battery is satisfactory or not due to the complete crack ( C2 ).
  • the second difference value 31 obtained through the second signal pattern detection step S152 and the preset second tolerance value 30 it is possible to determine whether a perfect crack (C3) exists in the inspection area (CA).
  • the second allowable error value 30 means a difference value between the reference signal SS and the second allowable error signal OKS2 .
  • the secondary battery may be determined to be a good product.
  • a complete crack C3 may exist in the inspection area CA, but in this case, the perfect crack C3 is the quality of the secondary battery. It can be judged as a crack to the extent that it does not affect the battery, and therefore, even in this case, the secondary battery can be judged to be a good product.
  • the complete crack C3 existing in the inspection area CA affects the quality of the secondary battery. It may be judged to be a crack to the extent that it has reached, and therefore, in this case, the secondary battery may be judged to be a defective product.
  • the probability of defective products increases as the first difference value 21 is larger than the first allowable error value 20 in the case of partial cracks C1, and the second difference value 31 is the second difference value 31 in case of complete cracks C2.
  • FIG. 10 is a flowchart illustrating a method for non-destructive inspection of internal cracks of a pouch-type secondary battery according to another embodiment of the present invention
  • FIG. 11 is an input signal synthesis step in the method for non-destructive inspection of internal cracks of a pouch-type secondary battery shown in FIG. It is an example diagram to explain.
  • the method for non-destructive testing of internal cracks of a pouch-type secondary battery according to the present embodiment may further include an input signal synthesis step ( S210 ).
  • the input signal synthesis step ( S210 ) may be performed before the input signal transmission step ( S120 ), and may be a step of synthesizing a plurality of input signals.
  • the first input signal and the second input signal may be synthesized.
  • the first input signal may have a first frequency
  • the second input signal may have a second frequency.
  • the first frequency may be lower than the second frequency.
  • the first frequency may be 1Khz
  • the second frequency may be 3Khz.
  • the input signal S1 in which the first input signal and the second input signal are synthesized is transmitted toward the inspection area CA through the transmitter 110, and the output signal S3 transformed while passing through the inspection area CA ) may be received by the receiver 120 .
  • FIG. 12 is an exemplary view for explaining an output signal decomposition step in the internal crack non-destructive inspection method of the pouch-type secondary battery shown in FIG. 10 .
  • the method for non-destructive testing of internal cracks of the pouch-type secondary battery according to the present embodiment may further include an output signal decomposition step ( S240 ).
  • the output signal decomposition step S240 may be performed after the output signal receiving step S130 , and may be a step of decomposing the plurality of output signals S3 from the output signal S3 .
  • the output signal decomposition step S140 according to the embodiment may decompose the first output signal and the second output signal.
  • the first output signal may be an output signal transformed while the first input signal passes through the inspection area CA
  • the second output signal may be an output signal transformed while the second input signal passes through the inspection region CA. have.
  • the first difference value 21 can be detected by comparing the first output signal (the output signal corresponding to the first input signal) with the reference signal SS
  • the second difference value 31 may be detected by comparing the second output signal (an output signal corresponding to the second input signal) with the reference signal SS.
  • the partial crack C1 having a relatively small or partially formed crack in the inspection area CA uses a relatively low-frequency first output signal to obtain a symmetrical or asymmetrical pattern of the output signal S3. By acquiring it, it is possible to accurately detect the partial crack (C1) state.
  • the partial crack C1 additionally uses the differential signal S4 from the output signal S3, the state of the partial crack C1 can be more accurately detected even with a relatively low frequency.
  • the size of cracks existing in the inspection area CA is relatively It is effective in detecting complete cracks (C2) that are large or continuously long.
  • the relatively high frequency signal loss can be minimized in the process of passing through the electrode tab 12 and the reception rate of the output signal S3 received by the receiver 120 can be increased, the relatively high frequency second output By using the signal, it is possible to more accurately detect the state of the complete crack C2 in which the size of the crack existing in the inspection area CA is relatively large or continuously long.
  • crack states having various sizes and patterns existing in the inspection area CA such as partial cracks C1 and complete cracks C2, are effectively removed. can be identified and detected.
  • the present invention is industrially applicable to the field of non-destructive inspection of internal cracks of secondary batteries capable of detecting cracks in electrodes existing inside the battery case.

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Abstract

A non-destructive inspection method for an internal crack in a pouch-type secondary battery, according to the present invention, comprises an input signal transmission step, an output signal reception step, a first signal pattern detection step, a second signal pattern detection step, a first crack state determination step, and a second crack state determination step. In the input signal transmission step, an input signal is transmitted toward an inspection area. In the output signal reception step, an output signal that is transformed while passing through the inspection area is received. In the first signal pattern detection step, the output signal and a preset reference signal are compared, and a first difference value between the output signal and the reference signal is detected, the first difference value caused by asymmetry between a first output signal area of the output signal disposed on one side and a second output signal area of the output signal disposed on the other side with respect to the center line of the reference signal. In the second signal pattern detection step, the output signal and the reference signal are compared, and a second difference value between the center value of the reference signal positioned on the center line of the reference signal and the center value of the output signal positioned on the center line of the output signal is detected. In the first crack state determination step, the first difference value and a preset first tolerance value are compared to determine whether a partial crack is present in the inspection area. In the second crack state determination step, the second difference value and a preset second tolerance value are compared to determine whether a complete crack is present in the inspection area.

Description

파우치형 이차전지의 내부균열 비파괴 검사방법Non-destructive testing method for internal cracks in pouch-type secondary batteries
본 발명은 파우치형 이차전지의 내부균열 비파괴 검사방법에 관한 것으로, 상세하게는 실링이 완료되어 밀봉된 전지 케이스의 내부에 존재하는 전극의 균열을 정확하게 검출할 수 있는 파우치형 이차전지의 내부균열 비파괴 검사방법에 관한 것이다.The present invention relates to a method for non-destructive inspection of internal cracks of a pouch-type secondary battery, and more particularly, to a non-destructive internal cracking inspection method of a pouch-type secondary battery capable of accurately detecting cracks in electrodes existing inside a sealed battery case It is about the inspection method.
이차전지는 전지의 형상 면에서 얇은 두께로 우수한 점유공간을 가지는 각형 배터리와 파우치형 전지에 대한 수요가 높고, 재료 면에서는 높은 에너지 밀도, 방전 전압, 출력 안정성을 가지는 리튬 이차전지에 대한 수요가 높다.Secondary batteries are in high demand for prismatic batteries and pouch-type batteries that are thin and have excellent occupancy space in terms of battery shape, and lithium secondary batteries with high energy density, discharge voltage, and output stability in terms of materials are in high demand. .
그리고, 이차전지는 양극/분리막/음극 구조의 전극조립체가 가지는 구조에 따라서 분류되기도 하는데, 대표적으로는 긴 시트형의 양극들과 음극들을 분리막이 개재된 상태에서 권취한 젤리롤 전극조립체와, 소정 크기의 단위로 절취한 다수의 양극과 음극들을 분리막을 개재한 상태로 순차적으로 적층한 스택형 전극조립체 등이 있다.In addition, secondary batteries are classified according to the structure of the electrode assembly having a positive electrode/separator/negative electrode structure. Typically, a jelly roll electrode assembly in which long sheet-shaped positive electrodes and negative electrodes are wound with a separator interposed therebetween, and a predetermined size There is a stack-type electrode assembly in which a plurality of positive and negative electrodes cut in units of , sequentially stacked with a separator interposed therebetween.
최근에는 스택형 전극조립체를 알루미늄 라미네이트 시트의 파우치형 케이스에 내장한 구조의 스택-파우치형 배터리가 많은 관심을 모으고 있으며, 이러한 스택-파우치형 배터리는 우수한 점유공간과, 효율적인 제조비용과, 적은 중량 및 용이한 형태 변형 등을 이유로 사용량이 점차 증가하고 있다.Recently, a stack-pouch-type battery with a structure in which a stack-type electrode assembly is embedded in a pouch-type case of an aluminum laminate sheet is attracting a lot of attention. And the amount of use is gradually increasing for reasons such as easy shape deformation.
이러한 스택-파우치형 배터리의 제조 과정을 간략히 설명하면, 먼저 소정 크기의 단위로 절단한 다수의 양극과 음극들을 분리막을 개재한 상태로 순차적으로 적층하여 스택형 전극조립체를 제작한다. 이후 전극조립체로부터 연장된 전극탭들에 전극리드를 열융착하여 연결한다. 이후 전극리드의 일부를 외부로 노출시킨 상태에서 전극조립체를 파우치형 케이스에 수납 장착한다. 이때 전극리드는 파우치형 케이스의 장착 과정에서 파우치형 케이스와 함께 열융착 결합된다. 이후 파우치형 케이스의 내부로 액체 전해질인 전해액을 주입한 다음 파우치형 케이스를 실링함으로써 제조를 완료하게 된다.Briefly describing the manufacturing process of such a stack-pouch type battery, first, a plurality of positive electrodes and negative electrodes cut into units of a predetermined size are sequentially stacked with a separator interposed therebetween to manufacture a stack type electrode assembly. Thereafter, the electrode leads are heat-sealed and connected to the electrode tabs extending from the electrode assembly. Thereafter, the electrode assembly is accommodated and mounted in a pouch-type case with a part of the electrode lead exposed to the outside. At this time, the electrode leads are thermally fused together with the pouch-type case during the mounting process of the pouch-type case. After that, an electrolyte, which is a liquid electrolyte, is injected into the pouch-type case, and then the pouch-type case is sealed to complete the manufacturing.
한편, 이러한 스택-파우치형 배터리의 제조 및 조립 공정 중에는 활물질이 도포된 전극 유지부 영역과 활물질이 도포되지 않은 전극 무지부 영역 간의 연신율 차이와, 용접에 의한 물리적 외력 등의 이유로 인하여, 전극탭 영역에서는 균열(Crack)이 발생할 수 있다. 이러한 내부 균열은 저전압 불량을 야기하게 된다.On the other hand, during the manufacturing and assembly process of such a stack-pouch type battery, due to the difference in elongation between the electrode holding part region to which the active material is applied and the electrode uncoated region to which the active material is not applied, and for reasons such as physical external force due to welding, the electrode tab region Cracks may occur. These internal cracks cause low voltage failure.
이러한 상황에서 전술한 바와 같이 스택-파우치형 배터리의 제조 및 조립 공정의 특성상 균열이 예상되는 영역은 파우치형 전지 케이스의 내부에 있기 때문에, 실링이 완료되어 밀봉된 상태에서는 내부균열을 외부에서 정확히 검출하거나 판단하기에 어려움이 있다.In this situation, as described above, due to the nature of the manufacturing and assembly process of the stack-pouch type battery, the area where cracks are expected is inside the pouch type battery case. or having difficulty judging.
상술한 문제점을 해결하기 위한 본 발명의 과제는 실링이 완료되어 밀봉된 전지 케이스 내부에 존재하는 전극의 균열을 정확하게 검출할 수 있는 파우치형 이차전지의 내부균열 비파괴 검사방법을 제공함에 있다.An object of the present invention for solving the above problems is to provide a non-destructive testing method for internal cracks in a pouch-type secondary battery capable of accurately detecting cracks in electrodes existing inside a sealed battery case after sealing is completed.
본 발명의 해결과제는 이상에서 언급한 것들에 한정되지 않으며, 언급되지 아니한 다른 해결과제들은 아래의 기재로부터 당업자에게 명확하게 이해될 수 있을 것이다.The problems to be solved of the present invention are not limited to those mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.
상술한 과제를 해결하기 위한 본 발명의 실시예에 따른 파우치형 이차전지의 내부균열 비파괴 검사방법은, 검사영역을 향하여 입력신호를 발신하는 입력신호 발신단계; 상기 입력신호가 상기 검사영역을 통과하면서 변형된 출력신호를 수신하는 출력신호 수신단계; 상기 출력신호와 미리 설정된 기준신호를 비교하되, 상기 기준신호의 중심선을 기준으로 일측에 배치되는 상기 출력신호의 제1출력신호영역과 타측에 배치되는 상기 출력신호의 제2출력신호영역의 비대칭에 의한 상기 기준신호와의 제1차이값을 검출하는 제1신호패턴 검출단계; 상기 출력신호와 상기 기준신호를 비교하되, 상기 기준신호의 중심선 상에 위치하는 상기 기준신호의 중심값과 상기 출력신호의 중심선 상에 위치하는 상기 출력신호의 중심값의 제2차이값을 검출하는 제2신호패턴 검출단계; 상기 제1차이값과 미리 설정된 제1허용오차값을 비교하여, 상기 검사영역에서 부분균열의 존재 여부를 판단하는 제1균열상태 판단단계; 및 상기 제2차이값과 미리 설정된 제2허용오차값을 비교하여, 상기 검사영역에서 완전균열의 존재 여부를 판단하는 제2균열상태 판단단계;를 포함하는 것을 특징으로 한다.An internal crack non-destructive inspection method of a pouch-type secondary battery according to an embodiment of the present invention for solving the above-described problems, an input signal sending step of sending an input signal toward the inspection area; an output signal receiving step of receiving a modified output signal while the input signal passes through the inspection area; Comparing the output signal and a preset reference signal, the asymmetry of the first output signal region of the output signal disposed on one side and the second output signal region of the output signal disposed on the other side with respect to the center line of the reference signal a first signal pattern detection step of detecting a first difference value from the reference signal by Comparing the output signal and the reference signal, and detecting a second difference value between the center value of the reference signal located on the center line of the reference signal and the center value of the output signal located on the center line of the output signal detecting a second signal pattern; a first crack state determination step of determining whether a partial crack exists in the inspection area by comparing the first difference value with a preset first allowable error value; and a second crack state determination step of determining whether a complete crack exists in the inspection area by comparing the second difference value with a preset second allowable error value.
본 실시예에 따른 파우치형 이차전지의 내부균열 비파괴 검사방법에 있어서, 상기 제1신호패턴 검출단계는, 상기 출력신호를 미분하여 미분신호를 생성하고, 상기 기준신호의 중심선을 기준으로, 일측에 배치되는 상기 미분신호의 제1미분신호영역의 제1최대피크값과, 타측에 배치되는 상기 미분신호의 제2미분신호영역의 제2최대피크값과의 차이값을 바탕으로, 상기 제1차이값을 검출할 수 있다.In the non-destructive inspection method for internal cracks of a pouch-type secondary battery according to the present embodiment, the first signal pattern detection step generates a differential signal by differentiating the output signal, and based on the center line of the reference signal, one side Based on a difference value between a first maximum peak value of a first differential signal region of the differential signal disposed on the other side and a second maximum peak value of a second differential signal region of the differential signal disposed on the other side, the first difference value can be detected.
본 실시예에 따른 파우치형 이차전지의 내부균열 비파괴 검사방법에 있어서, 상기 입력신호 발신단계 이전에 수행되며, 제1주파수를 가지는 제1입력신호와 상기 제1주파수와 다른 제2주파수를 가지는 제2입력신호를 합성하는 입력신호 합성단계;를 더 포함할 수 있다.In the non-destructive testing method for internal cracks of a pouch-type secondary battery according to the present embodiment, a first input signal having a first frequency and a second frequency different from the first frequency are performed before the step of transmitting the input signal. It may further include; an input signal synthesizing step of synthesizing two input signals.
본 실시예에 따른 파우치형 이차전지의 내부균열 비파괴 검사방법에 있어서, 상기 출력신호 수신단계 이후에 수행되며, 상기 출력신호로부터 상기 제1입력신호로부터 변형된 제1출력신호와 상기 제2입력신호로부터 변형된 제2출력신호를 분해하는 출력신호 분해단계;를 더 포함할 수도 있다.In the non-destructive testing method for internal cracks of a pouch-type secondary battery according to the present embodiment, the first output signal and the second input signal are performed after the step of receiving the output signal, and are transformed from the first input signal from the output signal The method may further include an output signal decomposition step of decomposing the transformed second output signal from .
본 실시예에 따른 파우치형 이차전지의 내부균열 비파괴 검사방법에 있어서, 상기 제1주파수는 부분균열의 존재 여부를 판단하는데 이용될 수 있고, 상기 제1주파수보다 고주파인 상기 제2주파수는 완전균열의 존재 여부를 판단하는데 이용될 수 있다. 이 경우 상기 제1신호패턴 검출단계는 상기 제1출력신호와 상기 기준신호를 비교하여 상기 제1차이값을 검출할 수 있고, 상기 제2신호패턴 검출단계는 상기 제2출력신호와 상기 기준신호를 비교하여 상기 제2차이값을 검출할 수 있다.In the non-destructive inspection method for internal cracks of a pouch-type secondary battery according to the present embodiment, the first frequency may be used to determine whether a partial crack exists, and the second frequency, which is higher than the first frequency, is a complete crack. can be used to determine the presence of In this case, the first signal pattern detection step may detect the first difference value by comparing the first output signal with the reference signal, and the second signal pattern detection step includes the second output signal and the reference signal. can be compared to detect the second difference value.
본 발명에 따르면, 기준신호에 대한 출력신호의 패턴을 검출 및 분석하여, 검사영역 내 존재하는 부분균열 혹은 완전균열에 의한 균열상태를 보다 신속하고 정확하게 검출 및 판단할 수 있다.According to the present invention, by detecting and analyzing the pattern of the output signal with respect to the reference signal, it is possible to more quickly and accurately detect and determine the crack state due to the partial crack or the complete crack existing in the inspection area.
본 발명의 효과는 이상에서 언급된 것들에 한정되지 않으며, 언급되지 아니한 다른 효과들은 아래의 기재로부터 당업자에게 명확하게 이해될 수 있을 것이다.Effects of the present invention are not limited to those mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the following description.
도 1은 본 발명의 일실시예에 따른 파우치형 이차전지의 내부균열 비파괴 검사장치를 나타낸 예시도이다.1 is an exemplary view showing an internal crack non-destructive testing apparatus of a pouch-type secondary battery according to an embodiment of the present invention.
도 2는 본 발명의 일실시예에 따른 파우치형 이차전지의 내부균열 비파괴 검사장치의 작동을 설명하기 위한 부분 단면 예시도이다.2 is a partial cross-sectional view for explaining the operation of the internal crack non-destructive inspection apparatus of a pouch-type secondary battery according to an embodiment of the present invention.
도 3은 본 발명의 일실시예에 따른 파우치형 이차전지의 내부균열이 형성되는 검사영역을 나타낸 부분 평면 예시도이다.3 is a partial plan view illustrating an inspection area in which an internal crack of a pouch-type secondary battery is formed according to an embodiment of the present invention.
도 4는 본 발명의 일실시예에 따른 파우치형 이차전지의 내부균열 비파괴 검사방법을 나타낸 흐름도이다.4 is a flowchart illustrating a method for non-destructive testing of internal cracks of a pouch-type secondary battery according to an embodiment of the present invention.
도 5는 검사영역 내 균열이 없는 경우, 본 발명의 일실시예에 따른 출력신호 및 기준신호를 나타낸 예시도이다.5 is an exemplary view showing an output signal and a reference signal according to an embodiment of the present invention when there is no crack in the inspection area.
도 6은 검사영역 내 부분균열이 있는 경우, 본 발명의 일실시예에 따른 출력신호 및 기준신호를 나타낸 예시도이다.6 is an exemplary view showing an output signal and a reference signal according to an embodiment of the present invention when there is a partial crack in the inspection area.
도 7은 검사영역 내 완전균열이 있는 경우, 본 발명의 일실시예에 따른 출력신호 및 기준신호를 나타낸 예시도이다.7 is an exemplary view showing an output signal and a reference signal according to an embodiment of the present invention when there is a complete crack in the inspection area.
도 8은 본 발명의 실시예에 따른 제1신호패턴 검출단계를 설명하기 위한 것으로, 검사영역 내 균열이 없는 경우, 출력신호(a 도면) 및 미분신호(b 도면)를 나타낸 예시도이다.8 is for explaining the first signal pattern detection step according to an embodiment of the present invention, and is an exemplary view showing an output signal (a diagram) and a differential signal (b diagram) when there is no crack in the inspection area.
도 9는 본 발명의 일실시예에 따른 제1신호패턴 검출단계를 설명하기 위한 것으로, 검사영역 내 부분균열이 있는 경우, 출력신호(a 도면) 및 미분신호(b 도면)를 나타낸 예시도이다.9 is an exemplary diagram illustrating an output signal (a diagram) and a differential signal (b diagram) when there is a partial crack in an inspection area, for explaining the first signal pattern detection step according to an embodiment of the present invention. .
도 10은 본 발명의 다른 실시예에 따른 파우치형 이차전지의 내부균열 비파괴 검사방법을 나타낸 흐름도이다.10 is a flowchart illustrating a method for non-destructive testing of internal cracks of a pouch-type secondary battery according to another embodiment of the present invention.
도 11은 도 10에 도시된 파우치형 이차전지의 내부균열 비파괴 검사방법에 있어서 입력신호 합성단계를 설명하기 위한 예시도이다.11 is an exemplary view for explaining an input signal synthesis step in the internal crack non-destructive inspection method of the pouch-type secondary battery shown in FIG. 10 .
도 12는 도 10에 도시된 파우치형 이차전지의 내부균열 비파괴 검사방법에 있어서 출력신호 분해단계를 설명하기 위한 예시도이다.12 is an exemplary view for explaining an output signal decomposition step in the internal crack non-destructive inspection method of the pouch-type secondary battery shown in FIG. 10 .
이하 상술한 해결하고자 하는 과제가 구체적으로 실현될 수 있는 본 발명의 바람직한 실시예들이 첨부된 도면을 참조하여 설명된다. 본 실시예들을 설명함에 있어서, 동일 구성에 대해서는 동일 명칭 및 동일 부호가 사용될 수 있으며 이에 따른 부가적인 설명은 생략될 수 있다.Hereinafter, preferred embodiments of the present invention in which the above-described problems to be solved can be specifically realized will be described with reference to the accompanying drawings. In describing the present embodiments, the same names and reference numerals may be used for the same components, and an additional description thereof may be omitted.
도 1은 본 발명의 일실시예에 따른 파우치형 이차전지의 내부균열 비파괴 검사장치를 나타낸 예시도이고, 도 2는 본 발명의 일실시예에 따른 파우치형 이차전지의 내부균열 비파괴 검사장치의 작동을 설명하기 위한 부분 단면 예시도이며, 도 3은 본 발명의 일실시예에 따른 파우치형 이차전지의 내부균열이 형성되는 검사영역을 나타낸 부분 평면 예시도이다.1 is an exemplary view showing an internal cracking non-destructive testing apparatus for a pouch-type secondary battery according to an embodiment of the present invention, and FIG. 2 is an operation of the internal cracking non-destructive testing apparatus for a pouch-type secondary battery according to an embodiment of the present invention. 3 is a partial plan view illustrating an inspection area in which internal cracks of a pouch-type secondary battery according to an embodiment of the present invention are formed.
도 1 내지 도 3을 참조하면, 본 발명의 일실시예에 따른 파우치형 이차전지의 내부균열 비파괴 검사방법은 파우치형 이차전지(10)의 제조 및 조립 공정에서 케이스(14)의 내부에 존재하는 균열 상태를 정확히 검출하여, 검출된 균열 상태를 바탕으로 이차전지(10)의 불량 여부를 정확히 판단할 수 있도록 하는 것이다.1 to 3, the internal crack non-destructive inspection method of the pouch-type secondary battery according to an embodiment of the present invention is present inside the case 14 in the manufacturing and assembly process of the pouch-type secondary battery 10. By accurately detecting the crack state, it is possible to accurately determine whether the secondary battery 10 is defective based on the detected crack state.
이를 위한, 파우치형 이차전지의 내부균열 검사장치로는 스택-파우치형 이차전지(10)에 한정되지 않고, 다양한 구조 및 형상을 가지는 이차전지에는 모두 적용될 수 있으며, 이하에서는 설명의 편의상 스택형 전극조립체(11)와 파우치형 케이스(14)를 가지는 스택-파우치형 이차전지(10)를 예로 설명한다.For this, the internal crack inspection apparatus of the pouch-type secondary battery is not limited to the stack-pouch-type secondary battery 10, and may be applied to all secondary batteries having various structures and shapes. Hereinafter, for convenience of description, the stack-type electrode A stack-pouch type secondary battery 10 having an assembly 11 and a pouch type case 14 will be described as an example.
도 1 내지 도 3을 참조하면, 먼저 본 발명에 따른 파우치형 이차전지의 내부균열 비파괴 검사방법을 수행하기 위한 파우치형 이차전지의 내부균열 비파괴 검사장치는 발신부(110), 수신부(120) 및 제어부(130)를 포함할 수 있다.1 to 3, first, the internal crack non-destructive testing apparatus of a pouch-type secondary battery for performing the internal crack non-destructive testing method of the pouch-type secondary battery according to the present invention is a transmitter 110, a receiver 120 and A control unit 130 may be included.
발신부(110)는 검사대상물인 이차전지(10)의 일측에 배치될 수 있다. 발신부(110)는 이차전지(10) 내부에 균열이 예상되는 검사영역(CA)을 향하여 입력신호(S1)를 발신할 수 있다.The transmitter 110 may be disposed on one side of the secondary battery 10 which is an inspection object. The transmitter 110 may transmit the input signal S1 toward the inspection area CA where cracks are expected inside the secondary battery 10 .
입력신호(S1)는 이차전지(10)의 검사영역(CA)을 통과할 수 있고, 검사영역(CA)을 통과하는 과정에서 검사영역(CA)에 위치하는 소재의 형상 및 재질 특성에 따라 반사, 굴절, 분산, 회절 등에 의하여 변형될 수 있다.The input signal S1 may pass through the inspection area CA of the secondary battery 10, and in the process of passing through the inspection area CA, the input signal S1 is reflected according to the shape and material characteristics of the material located in the inspection area CA. , can be deformed by refraction, dispersion, diffraction, and the like.
즉, 입력신호(S1)는 발신부(110) 및 수신부(120)의 사이에 이차전지(10)가 없는 경우 입력신호(S1)는 그대로 수신부(120)에 전달될 수 있고, 발신부(110) 및 수신부(120)의 사이에 이차전지(10)가 존재하는 경우 입력신호(S1)는 이차전지(10)를 통과한 다음 입력신호(S1)와 다른 출력신호(S3)로 변형되고, 이렇게 변형된 출력신호(S3)가 수신부(120)에 전달될 수 있다.That is, when there is no secondary battery 10 between the transmitter 110 and the receiver 120 , the input signal S1 may be transmitted to the receiver 120 as it is, and the transmitter 110 ) and when the secondary battery 10 is present between the receiving unit 120, the input signal S1 passes through the secondary battery 10 and then is transformed into an output signal S3 different from the input signal S1, like this The modified output signal S3 may be transmitted to the receiver 120 .
발신부(110)로는 와전류식 변위센서가 사용될 수 있다. 와전류식 변위센서를 이용한 발신부(110)는 코일에 교류 전류가 가해지면, 코일 주위에 1차 자기장(제1신호에 해당)이 형성된다. 1차 자기장이 형성된 발신부(110)를 이차전지(10)의 검사영역(CA)에 인접하게 위치시키면 전자기 유도 현상에 의하여 검사영역(CA)에 유도기전력이 발생하여 1차 자기장을 방해하는 와전류가 흐르게 된다. 결국 검사영역(CA)을 사이에 두고 발신부(110)의 반대편 영역에는 1차 자기장이 와전류에 의해 상쇄되면서 변형된 2차 자기장(제2신호에 해당)이 형성된다.An eddy current type displacement sensor may be used as the transmitter 110 . In the transmitter 110 using the eddy current type displacement sensor, when an alternating current is applied to the coil, a primary magnetic field (corresponding to the first signal) is formed around the coil. When the transmitter 110 in which the primary magnetic field is formed is positioned adjacent to the inspection area CA of the secondary battery 10, an eddy current that interferes with the primary magnetic field by generating an induced electromotive force in the inspection area CA due to electromagnetic induction will flow As a result, a transformed secondary magnetic field (corresponding to the second signal) is formed in an area opposite to the transmitter 110 with the inspection area CA interposed therebetween while the primary magnetic field is canceled by the eddy current.
수신부(120)는 검사대상물인 이차전지(10)의 타측에 배치될 수 있으며, 이차전지(10)를 사이에 두고 발신부(110)를 대향하도록 배치될 수 있다. 수신부(120)는 발신부(110)에서 발신된 입력신호(S1)가 이차전지(10)의 검사영역(CA)을 통과하면서 변형된 출력신호(S3)를 수신할 수 있다.The receiver 120 may be disposed on the other side of the secondary battery 10 as an inspection object, and may be disposed to face the transmitter 110 with the secondary battery 10 interposed therebetween. The receiving unit 120 may receive the modified output signal S3 while the input signal S1 transmitted from the transmitting unit 110 passes through the inspection area CA of the secondary battery 10 .
수신부(120) 역시 와전류식 변위센서가 사용될 수 있다. 즉, 발신부(110)를 통해 형성된 1차 자기장에 의하여 이차전지(10)의 검사영역(CA)에 유도기전력이 발생하여 1차 자기장을 방해하는 와전류가 흐르게 되면, 이차전지(10) 검사영역(CA)을 사이에 두고 발신부(110)의 반대편 영역에 배치된 수신부(120)는 1차 자기장이 와전류에 의해 상쇄되면서 변형된 2차 자기장에 해당하는 출력신호(S3)를 수신할 수 있다.The receiver 120 may also use an eddy current type displacement sensor. That is, when an eddy current that interferes with the primary magnetic field flows due to an induced electromotive force generated in the inspection area CA of the secondary battery 10 by the primary magnetic field formed through the transmitter 110 , the secondary battery 10 inspection area The receiver 120 disposed in the region opposite to the transmitter 110 with the CA interposed therebetween may receive the output signal S3 corresponding to the transformed secondary magnetic field while the primary magnetic field is canceled by the eddy current. .
부가 설명하면, 발신부(110)와 이차전지(10)의 검사영역(CA) 사이 공간은 1차 자기장(제1신호에 해당)의 영향만이 존재하는 구역일 수 있고, 이 구역에서는 자기장 신호의 세기가 강한 상태를 이룬다. 또한 이차전지(10)의 검사영역(CA)은 발신부(110)에서 형성된 1차 자기장과 와전류에 의해 형성된 2차 자기장의 상쇄가 일어나는 구역일 수 있고, 이 구역에서는 자기장 신호가 급격히 감소하게 된다. 또한 이차전지(10)의 검사영역(CA)과 수신부(120) 사이 공간은 2차 자기장(제2신호에 해당)의 영향만이 존재하는 구역일 수 있고, 이 구역에서 자기장 신호의 세기는 1차 자기장 영역보다는 작은 세기를 가진다.In addition, the space between the transmitter 110 and the inspection area CA of the secondary battery 10 may be a region where only the effect of the primary magnetic field (corresponding to the first signal) exists, and in this region, the magnetic field signal strength is strong. Also, the inspection area CA of the secondary battery 10 may be a region in which the primary magnetic field formed by the transmitter 110 and the secondary magnetic field formed by the eddy current are offset, and in this region, the magnetic field signal is rapidly reduced. . In addition, the space between the inspection area CA of the secondary battery 10 and the receiving unit 120 may be a region where only the effect of the secondary magnetic field (corresponding to the second signal) exists, and the strength of the magnetic field signal in this region is 1 It has a smaller strength than the secondary magnetic field.
이에 따라, 이차전지(10)를 사이에 두고 수신부(120)를 발신부(110)의 반대편에 배치하여 이차전지(10)의 검사영역(CA)을 통과하면서 상쇄된 2차 자기장의 세기를 바탕으로 검사영역(CA) 내부에 존재하는 균열을 검출할 수 있다.Accordingly, based on the strength of the secondary magnetic field canceled while passing through the inspection area CA of the secondary battery 10 by placing the receiving unit 120 on the opposite side of the transmitting unit 110 with the secondary battery 10 interposed therebetween. It is possible to detect cracks existing inside the inspection area CA.
한편, 본 실시예에 따른 이차전지(10)의 검사영역(CA)은 균열이 예상되는 부위로서, 검사영역(CA)는 전극탭(12)의 벤딩영역 또는 전극탭(12)과 전극리드(13)의 용접영역일 수 있다.On the other hand, the inspection area CA of the secondary battery 10 according to the present embodiment is a region where cracks are expected, and the inspection area CA is a bending region of the electrode tab 12 or the electrode tab 12 and the electrode lead ( 13) may be the welding area.
예를 들면, 파우치형 이차전지(10)의 제조 및 조립 공정 중, 활물질이 도포된 전극유지부 영역과 활물질이 도포되지 않은 전극무지부 영역 간의 연신율 차이와 용접에 의한 물리적 외력 등의 이유로 인하여, 전극탭(12) 영역에서는 균열이 발생할 수 있는데, 이러한 균열은 하나의 전극리드(13)에 복수의 전극탭(12)들이 연결되는 전극탭(12)의 벤딩영역 또는 전극탭(12)과 전극리드(13)의 용접영역에서 집중적으로 발생된다.For example, during the manufacturing and assembling process of the pouch-type secondary battery 10, due to the difference in elongation between the electrode holding part region to which the active material is applied and the electrode uncoated part region to which the active material is not applied, due to reasons such as physical external force caused by welding, etc. A crack may occur in the region of the electrode tab 12 . The crack may be a bending region of the electrode tab 12 in which a plurality of electrode tabs 12 are connected to one electrode lead 13 or the electrode tab 12 and the electrode. It is intensively generated in the welding area of the lead (13).
그리고 전극탭(12)의 벤딩영역에 존재하는 균열(C)은 전극탭(12)의 벤딩방향에 대해 교차하는 방향으로 연장되는 특성을 가지고, 전극탭(12)과 전극리드(13)의 용접영역에 존재하는 균열(C)은 용접부의 길이방향으로 연장되는 특성을 가진다. 즉, 전극탭(12)의 벤딩영역 및 전극탭(12)과 전극리드(13)의 용접영역에서 발생되는 균열(C)은 유사한 방향성을 가진다.In addition, the crack C existing in the bending region of the electrode tab 12 has a characteristic of extending in a direction crossing the bending direction of the electrode tab 12 , and welding of the electrode tab 12 and the electrode lead 13 . The crack (C) existing in the region has a characteristic of extending in the longitudinal direction of the weld. That is, cracks C generated in the bending region of the electrode tab 12 and the welding region between the electrode tab 12 and the electrode lead 13 have similar directions.
이하 파우치형 이차전지의 내부균열 비파괴 검사장치를 이용한 파우치형 이차전지의 내부균열 비파괴 검사방법을 설명하면 다음과 같다.Hereinafter, a method for non-destructive inspection of internal cracks of a pouch-type secondary battery using a non-destructive inspection device for internal cracks of a pouch-type secondary battery will be described.
도 4는 본 발명의 일실시예에 따른 파우치형 이차전지의 내부균열 비파괴 검사방법을 나타낸 흐름도이다.4 is a flowchart illustrating a method for non-destructive testing of internal cracks of a pouch-type secondary battery according to an embodiment of the present invention.
도 4를 참조하면, 본 발명의 일실시예에 따른 파우치형 이차전지의 내부균열 비파괴 검사방법은 입력신호 발신단계(S120), 출력신호 수신단계(S130), 제1신호패턴 검출단계(S151), 제2신호패턴 검출단계(S152), 제1균열상태 판단단계(S161), 제2균열상태 판단단계(S162)를 포함할 수 있다.Referring to FIG. 4 , the method for non-destructive inspection of internal cracks of a pouch-type secondary battery according to an embodiment of the present invention includes an input signal sending step (S120), an output signal receiving step (S130), and a first signal pattern detecting step (S151). , a second signal pattern detection step (S152), a first crack state determination step (S161), and a second crack state determination step (S162).
입력신호 발신단계(S120)는 이차전지(10)의 내부균열이 예상되는 검사영역(CA)을 향하여 입력신호(S1)를 발신하는 단계일 수 있다. 즉, 발신부(110)는 검사영역(CA)을 향하여 입력신호(S1)를 발신할 수 있다.The step of transmitting the input signal ( S120 ) may be a step of transmitting the input signal ( S1 ) toward the inspection area CA where the internal crack of the secondary battery 10 is expected. That is, the transmitter 110 may transmit the input signal S1 toward the examination area CA.
출력신호 수신단계(S130)는 입력신호(S1)가 검사영역(CA)을 통과하면서 변형된 출력신호(S3)를 수신하는 단계일 수 있다. 즉, 수신부(120)는 발신부(110)에서 발신된 후 검사영역(CA)를 통과하면서 변형된 출력신호(S3)를 수신할 수 있다.The output signal receiving step S130 may be a step of receiving the output signal S3 modified while the input signal S1 passes through the inspection area CA. That is, the receiver 120 may receive the modified output signal S3 while passing through the inspection area CA after being transmitted from the transmitter 110 .
출력신호(S3)는 검사영역(CA)의 일측에서 타측으로 이어지는 전체 구간에 대해 선형의 형태로 형성될 수 있다.The output signal S3 may be formed in a linear form for the entire section extending from one side to the other side of the inspection area CA.
한편, 본 발명에 따른 파우치형 이차전지의 내부균열 비파괴 검사방법은 신호 정렬단계를 더 포함할 수 있다.Meanwhile, the method for non-destructive inspection of internal cracks of a pouch-type secondary battery according to the present invention may further include a signal alignment step.
신호 정렬단계는 출력신호(S3)와 기준신호(SS)를 겹쳐서 정렬하는 단계일 수 있다. 즉, 신호 정렬단계는 기준신호(SS)의 중심값(SSc)을 교차하는 기준신호(SS)의 중심선(CL)에 출력신호(S3)의 중심값(S3c)을 교차하는 출력신호(S3)의 중심선을 일치시킴으로써, 기준신호(SS)에 출력신호(S3)를 정렬시킬 수 있다.The signal alignment step may be a step in which the output signal S3 and the reference signal SS are overlapped and aligned. That is, in the signal alignment step, the output signal S3 crossing the center value S3c of the output signal S3 to the center line CL of the reference signal SS crossing the center value SSc of the reference signal SS. By matching the center line of , it is possible to align the output signal S3 with the reference signal SS.
제1신호패턴 검출단계(S151)는 출력신호(S3)와 미리 설정된 기준신호(SS)를 비교하여, 출력신호(S3)의 제1패턴을 검출하는 단계일 수 있다.The first signal pattern detection step S151 may be a step of detecting a first pattern of the output signal S3 by comparing the output signal S3 with a preset reference signal SS.
즉, 제1신호패턴 검출단계(S151)는 기준신호(SS)의 중심선(CL)을 기준으로 출력신호(S3)가 대칭을 유지하는지 혹은 비대칭을 유지하는지를 검출할 수 있다. 이에 제1패턴은 출력신호(S3)의 대칭 혹은 비대칭 패턴을 의미한다.That is, the first signal pattern detection step S151 may detect whether the output signal S3 maintains symmetry or asymmetry with respect to the center line CL of the reference signal SS. Accordingly, the first pattern means a symmetrical or asymmetrical pattern of the output signal S3.
구체적으로, 도 5는 검사영역 내 균열이 없는 경우, 본 발명의 일실시예에 따른 출력신호 및 기준신호를 나타낸 일예이다.Specifically, FIG. 5 is an example showing an output signal and a reference signal according to an embodiment of the present invention when there is no crack in the inspection area.
도 5를 참조하면, 출력신호(S3)는 기준신호(SS)의 중심선(CL)을 기준으로 제1출력신호영역(S31) 및 제2출력신호영역(S32)이 구분될 수 있다. 즉, 제1출력신호영역(S31)은 기준신호(SS)의 중심선(CL)을 기준으로 출력신호(S3)의 일측을 형성하고, 제2출력신호영역(S32)은 기준신호(SS)의 중심선(CL)을 기준으로 출력신호(S3)의 타측을 형성할 수 있다.Referring to FIG. 5 , the output signal S3 may be divided into a first output signal region S31 and a second output signal region S32 based on the center line CL of the reference signal SS. That is, the first output signal region S31 forms one side of the output signal S3 with respect to the center line CL of the reference signal SS, and the second output signal region S32 is the reference signal SS. The other side of the output signal S3 may be formed based on the center line CL.
이때, 검사영역(CA)에 균열이 존재하지 않으면, 출력신호(S3)는 기준신호(SS)에 일치될 수 있고, 기준신호(SS)의 중심선(CL)을 기준으로 제1출력신호영역(S31) 및 제2출력신호영역(S32)이 정확하게 대칭될 수 있다.At this time, if there is no crack in the inspection area CA, the output signal S3 may match the reference signal SS, and the first output signal area ( S31) and the second output signal region S32 may be precisely symmetrical.
그리고, 도 6은 검사영역 내 부분균열이 있는 경우, 본 발명의 일실시예에 따른 출력신호 및 기준신호를 나타낸 일예이다.6 is an example showing an output signal and a reference signal according to an embodiment of the present invention when there is a partial crack in the inspection area.
도 6을 참조하면, 만약 검사영역(CA)에 부분균열(C1)이 존재하면, 출력신호(S3)는 기준신호(SS)의 중심선(CL)을 기준으로 제1출력신호영역(S31) 및 제2출력신호영역(S32)이 비대칭될 수 있다. 즉, 제1출력신호영역(S31)은 기준신호(SS)에 일치되는 반면 제2출력신호영역(S32)은 기준신호(SS)로부터 제1차이값(21)을 가질 수 있다.Referring to FIG. 6 , if there is a partial crack C1 in the inspection area CA, the output signal S3 is a first output signal area S31 and The second output signal region S32 may be asymmetrical. That is, the first output signal region S31 may match the reference signal SS, while the second output signal region S32 may have a first difference value 21 from the reference signal SS.
결과적으로, 제1신호패턴 검출단계(S151)는 출력신호(S3)의 대칭 혹은 비대칭 패턴을 검출할 수 있고, 기준신호(SS)의 중심선(CL)을 기준으로 제1출력신호영역(S31) 및 제2출력신호영역(S32)의 비대칭에 의한 제1차이값(21)을 통하여 출력신호(S3)의 비대칭 정도를 정확하게 검출할 수 있다. 이로 인하여 검사영역(CA)에 부분균열(C1)이 존재하는지 여부를 검출할 수 있다.As a result, in the first signal pattern detection step S151 , a symmetrical or asymmetrical pattern of the output signal S3 may be detected, and the first output signal region S31 based on the center line CL of the reference signal SS. And it is possible to accurately detect the degree of asymmetry of the output signal S3 through the first difference value 21 due to the asymmetry of the second output signal region S32. Accordingly, it is possible to detect whether the partial crack C1 exists in the inspection area CA.
만약 검사영역(CA)에 존재하는 균열의 크기가 미세할 경우, 제1신호패턴 검출단계(S151)에서 제1차이값(21)은 그 크기가 미세하여 검출이 용이하지 않을 수 있다.If the size of the crack existing in the inspection area CA is small, the first difference value 21 in the first signal pattern detection step S151 may not be easily detected because the size is small.
이를 위해 본 실시예에 따른 제1신호패턴 검출단계(S151)는 출력신호(S3) 및 기준신호(SS)의 대칭 혹은 비대칭에 의한 제1차이값(21)의 크기를 증폭할 수 있는 수단을 더 포함할 수 있다.To this end, the first signal pattern detection step S151 according to the present embodiment includes means for amplifying the magnitude of the first difference value 21 due to the symmetry or asymmetry of the output signal S3 and the reference signal SS. may include more.
도 8은 본 발명의 다른 실시예에 따른 제1신호패턴 검출단계를 설명하기 위한 것으로, 검사영역 내 균열이 없는 경우, 출력신호(a 도면) 및 미분신호(b 도면)를 나타낸 일예이고, 도 9는 본 발명의 일실시예에 따른 제1신호패턴 검출단계를 설명하기 위한 것으로, 검사영역 내 부분균열이 있는 경우, 출력신호(a 도면) 및 미분신호(b 도면)를 나타낸 일예이다.8 is for explaining the first signal pattern detection step according to another embodiment of the present invention, and is an example showing an output signal (a diagram) and a differential signal (b diagram) when there is no crack in the inspection area, FIG. 9 is for explaining the first signal pattern detection step according to an embodiment of the present invention, and is an example of an output signal (a diagram) and a differential signal (b diagram) when there is a partial crack in the inspection area.
도 8 및 도 9를 참조하면, 본 실시예에 따른 제1신호패턴 검출단계(S151)는 출력신호(S3)를 미분하여 미분신호(S4)를 생성하고, 이렇게 생성된 미분신호(S4)를 이용함으로써, 출력신호(S3) 및 기준신호(SS)의 대칭 혹은 비대칭에 의한 제1차이값(21)을 보다 정확하게 검출할 수 있다.8 and 9, in the first signal pattern detection step S151 according to the present embodiment, a differential signal S4 is generated by differentiating the output signal S3, and the differential signal S4 thus generated is By using this, the first difference value 21 due to symmetry or asymmetry between the output signal S3 and the reference signal SS can be more accurately detected.
먼저 도 8에서와 같이, 출력신호(S3)로부터 생성된 미분신호(S4)는 기준신호(SS)의 중심선(CL)을 기준으로 제1미분신호영역(S41) 및 제2미분신호영역(S42)이 구분될 수 있다. 즉, 제1미분신호영역(S41)은 기준신호(SS)의 중심선(CL)을 기준으로 미분신호(S4)의 일측을 형성하고, 제2미분신호영역(S42)은 기준신호(SS)의 중심선(CL)을 기준으로 미분신호(S4)의 타측을 형성할 수 있다.First, as shown in FIG. 8 , the differential signal S4 generated from the output signal S3 is a first differential signal region S41 and a second differential signal region S42 with respect to the center line CL of the reference signal SS. ) can be distinguished. That is, the first differential signal region S41 forms one side of the differential signal S4 with respect to the center line CL of the reference signal SS, and the second differential signal region S42 is the reference signal SS. The other side of the differential signal S4 may be formed based on the center line CL.
이때, 검사영역(CA)에 균열이 존재하지 않으면, 도 8 (a)에서와 같이 출력신호(S3)는 기준신호(SS)에 일치될 수 있고, 도 8 (b)에서와 같이 제1미분신호영역(S41)의 제1최대피크값(S411)과, 제2미분신호영역(S42)의 제2최대피크값(S421)은 동일한 값(높이: H1=H2)을 가질 수 있다. 즉, 이때 제1차이값(21: 도 6 참조)은 제로(0)일 수 있다.At this time, if there is no crack in the inspection area CA, the output signal S3 may coincide with the reference signal SS as in FIG. 8 (a), and the first differential as in FIG. 8 (b) The first maximum peak value S411 of the signal region S41 and the second maximum peak value S421 of the second differential signal region S42 may have the same value (height: H1=H2). That is, in this case, the first difference value 21 (refer to FIG. 6 ) may be zero (0).
만약 검사영역(CA)에 부분균열(C1)이 존재하면, 도 9 (a)에서와 같이, 출력신호(S3)는 기준신호(SS)의 중심선(CL)을 기준으로 제1출력신호영역(S31) 및 제2출력신호영역(S32)이 비대칭일 수 있고, 도 9 (b)에서와 같이, 제1미분신호영역(S41)의 제1최대피크값(S411)과, 제2미분신호영역(S42)의 제2최대피크값(S421)은 서로 다른 값(높이: H1>H2)을 가질 수 있다. 즉, 제1미분신호영역(S41)의 제1최대피크값(S411)과 제2미분신호영역(S42)의 제2최대피크값(S421)의 차이값(21")을 바탕으로 제1차이값(21)을 보다 정확하게 확인 및 검출할 수 있다.If there is a partial crack C1 in the inspection area CA, as shown in FIG. 9 (a), the output signal S3 is the first output signal area ( S31) and the second output signal region S32 may be asymmetric, and as shown in FIG. 9(b) , the first maximum peak value S411 of the first differential signal region S41 and the second differential signal region The second maximum peak value S421 of S42 may have different values (height: H1>H2). That is, based on the difference value 21" between the first maximum peak value S411 of the first differential signal region S41 and the second maximum peak value S421 of the second differential signal region S42, the first difference The value 21 can be more accurately identified and detected.
제2신호패턴 검출단계(S152)는 출력신호(S3)와 미리 설정된 기준신호(SS)를 비교하여, 출력신호(S3)의 제2패턴을 검출하는 단계일 수 있다.The second signal pattern detection step S152 may be a step of detecting a second pattern of the output signal S3 by comparing the output signal S3 with a preset reference signal SS.
즉, 제2신호패턴 검출단계(S152)는 기준신호(SS)의 중심선(CL) 상에 위치하는 기준신호(SS)의 중심값(S3c)과 출력신호(S3)의 중심선(CL) 상에 위치하는 출력신호(S3)의 중심값(S3c)과의 간격을 검출할 수 있다. 이에 따라 제2패턴은 기준신호(SS)의 중심값(SSc)으로부터 출력신호(S3)의 중심값(S3c)이 오프셋(offset) 되는 정도를 의미한다.That is, the second signal pattern detection step S152 is performed on the center value S3c of the reference signal SS positioned on the center line CL of the reference signal SS and the center line CL of the output signal S3. It is possible to detect an interval between the positioned output signal S3 and the center value S3c. Accordingly, the second pattern refers to the degree to which the center value S3c of the output signal S3 is offset from the center value SSc of the reference signal SS.
구체적으로, 도 5를 참조하면, 검사영역(CA)에 균열이 존재하지 않으면, 출력신호(S3)는 기준신호(SS)에 일치될 수 있고, 기준신호(SS)의 중심값(SSc) 및 출력신호(S3)의 중심값(S3c)은 서로 일치될 수 있다.Specifically, referring to FIG. 5 , if there is no crack in the inspection area CA, the output signal S3 may match the reference signal SS, and the center value SSc of the reference signal SS and The center value S3c of the output signal S3 may coincide with each other.
그리고, 도 7은 검사영역 내 완전균열이 있는 경우, 본 발명의 일실시예에 따른 출력신호 및 기준신호를 나타낸 일예이다.And, Figure 7 is an example showing the output signal and the reference signal according to an embodiment of the present invention when there is a complete crack in the inspection area.
도 7을 추가 참조하면, 만약 검사영역(CA)에 완전균열(C2)이 존재하면, 출력신호(S3)의 제1출력신호영역(S31) 및 제2출력신호영역(S32)은 대칭될 수 있고, 이때 출력신호(S3)의 중심값(S3c) 및 기준신호(SS)의 중심값(SSc)은 서로 이격될 수 있다. 즉, 기준신호(SS)의 중심값(SSc)으로부터 출력신호(S3)의 중심값(S3c)은 제2차이값(31)을 가지면서 이격될 수 있다.Referring further to FIG. 7 , if the complete crack C2 exists in the inspection area CA, the first output signal area S31 and the second output signal area S32 of the output signal S3 may be symmetrical. In this case, the center value S3c of the output signal S3 and the center value SSc of the reference signal SS may be spaced apart from each other. That is, the center value S3c of the output signal S3 may be spaced apart from the center value SSc of the reference signal SS while having the second difference value 31 .
결과적으로, 제2신호패턴 검출단계(S152)는 기준신호(SS)로부터 출력신호(S3)이 이격된 오프셋 정도를 검출할 수 있고, 출력신호(S3)의 중심값(S3c) 및 기준신호(SS)의 중심값(SSc) 사이의 제2차이값(31)을 검출할 수 있다. 이로 인하여 검사영역(CA)에 완전균열(C2)이 존재하는지 여부를 검출할 수 있다.As a result, in the second signal pattern detection step S152, the degree of offset by which the output signal S3 is spaced apart from the reference signal SS can be detected, and the center value S3c of the output signal S3 and the reference signal ( A second difference value 31 between the center values SSc of SS) may be detected. Due to this, it is possible to detect whether the perfect crack C2 exists in the inspection area CA.
제1균열상태 판단단계(S161)는 부분균열(C1)에 의한 이차전지의 양불을 판단하는 단계일 수 있다.The first crack state determination step S161 may be a step of determining whether or not the secondary battery is defective due to the partial crack C1.
다시 도 5 및 도 6을 참조하면, 제1균열상태 판단단계(S161)는 제1신호패턴 검출단계(S151)를 통해 획득된 제1차이값(21)과 미리 설정된 제1허용오차값(20)을 비교하여, 검사영역(CA)에서 부분균열(C2)의 존재 여부를 판단할 수 있다. 제1허용오차값(20)은 기준신호(SS)와 제1허용오차신호(OKS1)와의 차이값을 의미한다.5 and 6 again, in the first crack state determination step S161, the first difference value 21 obtained through the first signal pattern detection step S151 and the preset first tolerance value 20 ), it is possible to determine whether the partial crack C2 exists in the inspection area CA. The first allowable error value 20 means a difference value between the reference signal SS and the first allowable error signal OKS1 .
만약, 도 5에서와 같이, 제1차이값(21)이 검출되지 않을 경우, 검사영역(CA)에 부분균열(C2)이 존재하지 않으므로, 이차전지는 양품으로 판단될 수 있다.If, as shown in FIG. 5 , when the first difference value 21 is not detected, since the partial crack C2 does not exist in the inspection area CA, the secondary battery may be determined to be a good product.
또한, 제1차이값(21)이 제1허용오차값(20)보다 작을 경우, 검사영역(CA)에 부분균열(C2)이 존재할 수 있지만, 이 경우 부분균열(C2)은 이차전지의 품질에 영향을 미치지 않는 정도의 균열로 판단될 수 있고, 따라서 이 경우에도 이차전지는 양품으로 판단될 수 있다.In addition, when the first difference value 21 is smaller than the first allowable error value 20, a partial crack C2 may exist in the inspection area CA, but in this case, the partial crack C2 is the quality of the secondary battery. It can be judged as a crack to the extent that it does not affect the battery, and therefore, even in this case, the secondary battery can be judged to be a good product.
만약, 도 6에서와 같이, 제1차이값(21)이 제1허용오차값(20)보다 클 경우에는, 검사영역(CA)에 존재하는 부분균열(C2)은 이차전지의 품질에 영향을 미칠 정도의 균열로 판단될 수 있고, 따라서 이 경우에는 이차전지는 불량품으로 판단될 수 있다.If, as shown in FIG. 6 , when the first difference value 21 is greater than the first allowable error value 20 , the partial crack C2 existing in the inspection area CA affects the quality of the secondary battery. It may be judged to be a crack to the extent that it has reached, and therefore, in this case, the secondary battery may be judged to be a defective product.
제2균열상태 판단단계(S162)는 완전균열(C2)에 의한 이차전지의 양불을 판단하는 단계일 수 있다.The second crack state determination step ( S162 ) may be a step of determining whether the secondary battery is satisfactory or not due to the complete crack ( C2 ).
다시 도 5 및 도 7을 참조하면, 제2균열상태 판단단계(S162)는 제2신호패턴 검출단계(S152)를 통해 획득된 제2차이값(31)과 미리 설정된 제2허용오차값(30)을 비교하여, 검사영역(CA)에서 완전균열(C3)의 존재 여부를 판단할 수 있다.5 and 7 again, in the second crack state determination step S162, the second difference value 31 obtained through the second signal pattern detection step S152 and the preset second tolerance value 30 ), it is possible to determine whether a perfect crack (C3) exists in the inspection area (CA).
제2허용오차값(30)은 기준신호(SS)와 제2허용오차신호(OKS2)와의 차이값을 의미한다.The second allowable error value 30 means a difference value between the reference signal SS and the second allowable error signal OKS2 .
만약, 도 5에서와 같이, 제2차이값(31)이 검출되지 않을 경우, 검사영역(CA)에 완전균열(C3)이 존재하지 않으므로, 이차전지는 양품으로 판단될 수 있다.If, as shown in FIG. 5 , when the second difference value 31 is not detected, since the perfect crack C3 does not exist in the inspection area CA, the secondary battery may be determined to be a good product.
또한, 제2차이값(31)이 제2허용오차값(30)보다 작을 경우, 검사영역(CA)에 완전균열(C3)이 존재할 수 있지만, 이 경우 완전균열(C3)은 이차전지의 품질에 영향을 미치지 않는 정도의 균열로 판단될 수 있고, 따라서 이 경우에도 이차전지는 양품으로 판단될 수 있다.In addition, when the second difference value 31 is smaller than the second allowable error value 30, a complete crack C3 may exist in the inspection area CA, but in this case, the perfect crack C3 is the quality of the secondary battery. It can be judged as a crack to the extent that it does not affect the battery, and therefore, even in this case, the secondary battery can be judged to be a good product.
만약, 도 7에서와 같이, 제2차이값(31)이 제2허용오차값(30)보다 클 경우에는, 검사영역(CA)에 존재하는 완전균열(C3)은 이차전지의 품질에 영향을 미칠 정도의 균열로 판단될 수 있고, 따라서 이 경우에는 이차전지는 불량품으로 판단될 수 있다.If, as shown in FIG. 7 , when the second difference value 31 is greater than the second allowable error value 30 , the complete crack C3 existing in the inspection area CA affects the quality of the secondary battery. It may be judged to be a crack to the extent that it has reached, and therefore, in this case, the secondary battery may be judged to be a defective product.
결과적으로, 부분균열(C1) 시에는 제1차이값(21)이 제1허용오차값(20)보다 클수록 불량품 확률이 커지고, 완전균열(C2) 시에는 제2차이값(31)이 제2허용오차값(30)보다 클수록 불량품 확률이 커진다.As a result, the probability of defective products increases as the first difference value 21 is larger than the first allowable error value 20 in the case of partial cracks C1, and the second difference value 31 is the second difference value 31 in case of complete cracks C2. The greater the tolerance value 30, the greater the probability of defective products.
도 10은 본 발명의 다른 실시예에 따른 파우치형 이차전지의 내부균열 비파괴 검사방법을 나타낸 흐름도이고, 도 11은 도 9에 도시된 파우치형 이차전지의 내부균열 비파괴 검사방법에 있어서 입력신호 합성단계를 설명하기 위한 예시도이다.10 is a flowchart illustrating a method for non-destructive inspection of internal cracks of a pouch-type secondary battery according to another embodiment of the present invention, and FIG. 11 is an input signal synthesis step in the method for non-destructive inspection of internal cracks of a pouch-type secondary battery shown in FIG. It is an example diagram to explain.
도 10 및 도 11을 참조하면, 본 실시예에 따른 파우치형 이차전지의 내부균열 비파괴 검사방법은 입력신호 합성단계(S210)를 더 포함할 수 있다.10 and 11 , the method for non-destructive testing of internal cracks of a pouch-type secondary battery according to the present embodiment may further include an input signal synthesis step ( S210 ).
입력신호 합성단계(S210)는 입력신호 발신단계(S120) 이전에 수행될 수 있으며, 복수의 입력신호를 합성하는 단계일 수 있다. 실시예에 따른 입력신호 합성단계(S210)는 제1입력신호 및 제2입력신호를 합성할 수 있다.The input signal synthesis step ( S210 ) may be performed before the input signal transmission step ( S120 ), and may be a step of synthesizing a plurality of input signals. In the input signal synthesis step S210 according to the embodiment, the first input signal and the second input signal may be synthesized.
제1입력신호는 제1주파수를 가질 수 있고, 제2입력신호는 제2주파수를 가질 수 있다. 이때, 제1주파수는 제2주파수보다 낮을 수 있다. 실시예에 따르면, 제1주파수는 1Khz일 수 있고, 제2주파수는 3Khz일 수 있다.The first input signal may have a first frequency, and the second input signal may have a second frequency. In this case, the first frequency may be lower than the second frequency. According to an embodiment, the first frequency may be 1Khz, and the second frequency may be 3Khz.
이와 같이, 서로 다른 주파수를 가지는 복수의 입력신호를 합성하고, 이렇게 합성된 복수의 입력신호를 검사영역(CA)에 발신함으로써, 다양한 크기 및 패턴을 가지는 균열(C)을 보다 정확히 검출할 수 있다.In this way, by synthesizing a plurality of input signals having different frequencies and transmitting the plurality of input signals thus synthesized to the inspection area CA, cracks C having various sizes and patterns can be more accurately detected. .
이처럼 제1입력신호 및 제2입력신호가 합성된 입력신호(S1)는 발신부(110)를 통하여 검사영역(CA)을 향해 발신되고, 검사영역(CA)을 통과하면서 변형된 출력신호(S3)는 수신부(120)에서 수신될 수 있다.As such, the input signal S1 in which the first input signal and the second input signal are synthesized is transmitted toward the inspection area CA through the transmitter 110, and the output signal S3 transformed while passing through the inspection area CA ) may be received by the receiver 120 .
도 12는 도 10에 도시된 파우치형 이차전지의 내부균열 비파괴 검사방법에 있어서 출력신호 분해단계를 설명하기 위한 예시도이다.12 is an exemplary view for explaining an output signal decomposition step in the internal crack non-destructive inspection method of the pouch-type secondary battery shown in FIG. 10 .
도 10 및 도 12를 참조하면, 본 실시예에 따른 파우치형 이차전지의 내부균열 비파괴 검사방법은 출력신호 분해단계(S240)를 더 포함할 수 있다.Referring to FIGS. 10 and 12 , the method for non-destructive testing of internal cracks of the pouch-type secondary battery according to the present embodiment may further include an output signal decomposition step ( S240 ).
출력신호 분해단계(S240)는 출력신호 수신단계(S130) 이후에 수행될 수 있으며, 출력신호(S3)로부터 복수의 출력신호(S3)를 분해하는 단계일 수 있다. 실시예에 따른 출력신호 분해단계(S140)는 제1출력신호 및 제2출력신호를 분해할 수 있다.The output signal decomposition step S240 may be performed after the output signal receiving step S130 , and may be a step of decomposing the plurality of output signals S3 from the output signal S3 . The output signal decomposition step S140 according to the embodiment may decompose the first output signal and the second output signal.
즉, 제1출력신호는 제1입력신호가 검사영역(CA)을 통과하면서 변형된 출력신호일 수 있고, 제2출력신호는 제2입력신호가 검사영역(CA)을 통과하면서 변형된 출력신호일 수 있다.That is, the first output signal may be an output signal transformed while the first input signal passes through the inspection area CA, and the second output signal may be an output signal transformed while the second input signal passes through the inspection region CA. have.
이에 따라, 제1신호패턴 검출단계(S151)는 제1출력신호(제1입력신호에 대응하는 출력신호)와 기준신호(SS)를 비교하여 제1차이값(21)을 검출할 수 있고, 제2신호패턴 검출단계(S152)는 제2출력신호(제2입력신호에 대응하는 출력신호)와 기준신호(SS)를 비교하여 제2차이값(31)을 검출할 수 있다.Accordingly, in the first signal pattern detection step S151, the first difference value 21 can be detected by comparing the first output signal (the output signal corresponding to the first input signal) with the reference signal SS, In the second signal pattern detection step S152 , the second difference value 31 may be detected by comparing the second output signal (an output signal corresponding to the second input signal) with the reference signal SS.
기본적으로 상대적으로 저주파의 입력신호를 이용할 경우, 전극탭(12)에 존재하는 미세 균열(C)의 크기 및 패턴 검출에 효과적이다. 따라서, 검사영역(CA) 내 존재하는 균열의 크기가 상대적으로 작거나 부분적으로 형성된 부분균열(C1)은, 상대적으로 저주파수인 제1출력신호를 이용하여 출력신호(S3)의 대칭 혹은 비대칭 패턴을 획득함으로써, 부분균열(C1) 상태를 정확히 검출할 수 있다.Basically, when a relatively low frequency input signal is used, it is effective to detect the size and pattern of the microcracks C present in the electrode tab 12 . Accordingly, the partial crack C1 having a relatively small or partially formed crack in the inspection area CA uses a relatively low-frequency first output signal to obtain a symmetrical or asymmetrical pattern of the output signal S3. By acquiring it, it is possible to accurately detect the partial crack (C1) state.
더불어, 부분균열(C1)은 출력신호(S3)로부터 추가적으로 미분신호(S4)를 이용함으로써, 상대적인 저주파수를 이용하더라도 부분균열(C1) 상태를 보다 정확하게 검출할 수 있다.In addition, since the partial crack C1 additionally uses the differential signal S4 from the output signal S3, the state of the partial crack C1 can be more accurately detected even with a relatively low frequency.
또한, 멀티 주파수 중 상대적으로 고주파수는 상대적으로 검사영역(CA)인 전극탭(12)의 형상에 의한 변형은 최소화되면서 직전성이 우수하기 때문에, 검사영역(CA) 내 존재하는 균열의 크기가 상대적으로 크거나 연속적으로 길게 형성된 완전균열(C2) 검출에 효과적이다.In addition, since the relatively high frequency among the multi-frequency is excellent in electrical resistance while the deformation due to the shape of the electrode tab 12, which is a relatively inspection area CA, is minimized, the size of cracks existing in the inspection area CA is relatively It is effective in detecting complete cracks (C2) that are large or continuously long.
상대적으로 고주파수는 전극탭(12)을 통과하는 과정에서 신호 손실이 최소화될 수 있고, 수신부(120)에서 수신되는 출력신호(S3)의 수신율이 증가될 수 있기 때문에, 상대적으로 고주파수인 제2출력신호를 이용함으로써 검사영역(CA) 내 존재하는 균열의 크기가 상대적으로 크거나 연속적으로 길게 형성된 완전균열(C2) 상태를 보다 정확히 검출할 수 있다.Since the relatively high frequency signal loss can be minimized in the process of passing through the electrode tab 12 and the reception rate of the output signal S3 received by the receiver 120 can be increased, the relatively high frequency second output By using the signal, it is possible to more accurately detect the state of the complete crack C2 in which the size of the crack existing in the inspection area CA is relatively large or continuously long.
결과적으로, 서로 다른 주파수를 갖는 복수의 입력신호(S1)를 이용함으로써, 부분균열(C1) 및 완전균열(C2)과 같이 검사영역(CA)에 존재하는 다양한 크기 및 패턴을 가지는 균열 상태를 효과적으로 확인 및 검출할 수 있다.As a result, by using a plurality of input signals S1 having different frequencies, crack states having various sizes and patterns existing in the inspection area CA, such as partial cracks C1 and complete cracks C2, are effectively removed. can be identified and detected.
상술한 바와 같이 도면을 참조하여 본 발명의 바람직한 실시예를 설명하였지만, 해당 기술 분야의 숙련된 당업자라면, 하기의 청구범위에 기재된 본 발명의 사상 및 영역으로부터 벗어나지 않는 범위 내에서 본 발명을 다양하게 수정 또는 변경시킬 수 있다.Although the preferred embodiment of the present invention has been described with reference to the drawings as described above, those skilled in the art may vary the present invention in various ways without departing from the spirit and scope of the present invention as set forth in the following claims. may be modified or changed.
본 발명은 전지 케이스의 내부에 존재하는 전극의 균열을 검출할 수 있는 이차전지의 내부균열 비파괴 검사 기술 분야에 산업상 이용가능하다.The present invention is industrially applicable to the field of non-destructive inspection of internal cracks of secondary batteries capable of detecting cracks in electrodes existing inside the battery case.

Claims (5)

  1. 검사영역을 향하여 입력신호를 발신하는 입력신호 발신단계;an input signal sending step of sending an input signal toward the inspection area;
    상기 입력신호가 상기 검사영역을 통과하면서 변형된 출력신호를 수신하는 출력신호 수신단계;an output signal receiving step of receiving a deformed output signal while the input signal passes through the inspection area;
    상기 출력신호와 미리 설정된 기준신호를 비교하되, 상기 기준신호의 중심선을 기준으로 일측에 배치되는 상기 출력신호의 제1출력신호영역과 타측에 배치되는 상기 출력신호의 제2출력신호영역의 비대칭에 의한 상기 기준신호와의 제1차이값을 검출하는 제1신호패턴 검출단계;Comparing the output signal and a preset reference signal, the asymmetry of the first output signal region of the output signal disposed on one side and the second output signal region of the output signal disposed on the other side with respect to the center line of the reference signal a first signal pattern detection step of detecting a first difference value from the reference signal by
    상기 출력신호와 상기 기준신호를 비교하되, 상기 기준신호의 중심선 상에 위치하는 상기 기준신호의 중심값과 상기 출력신호의 중심선 상에 위치하는 상기 출력신호의 중심값의 제2차이값을 검출하는 제2신호패턴 검출단계;Comparing the output signal and the reference signal, and detecting a second difference value between the center value of the reference signal located on the center line of the reference signal and the center value of the output signal located on the center line of the output signal a second signal pattern detection step;
    상기 제1차이값과 미리 설정된 제1허용오차값을 비교하여, 상기 검사영역에서 부분균열의 존재 여부를 판단하는 제1균열상태 판단단계; 및a first crack state determination step of determining whether a partial crack exists in the inspection area by comparing the first difference value with a preset first allowable error value; and
    상기 제2차이값과 미리 설정된 제2허용오차값을 비교하여, 상기 검사영역에서 완전균열의 존재 여부를 판단하는 제2균열상태 판단단계;를 포함하는 것을 특징으로 하는 파우치형 이차전지의 내부균열 비파괴 검사방법.A second crack state determination step of determining whether a complete crack exists in the inspection area by comparing the second difference value with a preset second tolerance value; Non-destructive testing method.
  2. 제1항에 있어서,According to claim 1,
    상기 제1신호패턴 검출단계는,The first signal pattern detection step,
    상기 출력신호를 미분하여 미분신호를 생성하고, 상기 기준신호의 중심선을 기준으로, 일측에 배치되는 상기 미분신호의 제1미분신호영역의 제1최대피크값과, 타측에 배치되는 상기 미분신호의 제2미분신호영역의 제2최대피크값과의 차이값을 바탕으로, 상기 제1차이값을 검출하는 것을 특징으로 하는 파우치형 이차전지의 내부균열 비파괴 검사방법.A differential signal is generated by differentiating the output signal, and the first maximum peak value of the first differential signal region of the differential signal disposed on one side and the differential signal disposed on the other side with respect to the center line of the reference signal A method for non-destructive testing of internal cracks in a pouch-type secondary battery, characterized in that the first difference value is detected based on the difference value from the second maximum peak value of the second differential signal region.
  3. 제1항에 있어서,According to claim 1,
    상기 입력신호 발신단계 이전에 수행되며, 제1주파수를 가지는 제1입력신호와, 상기 제1주파수와 다른 제2주파수를 가지는 제2입력신호를 합성하는 입력신호 합성단계;를 더 포함하는 것을 특징으로 하는 파우치형 이차전지의 내부균열 비파괴 검사방법.and an input signal synthesis step of synthesizing a first input signal having a first frequency and a second input signal having a second frequency different from the first frequency, which is performed before the step of transmitting the input signal. A non-destructive testing method for internal cracks in pouch-type secondary batteries.
  4. 제3항에 있어서,4. The method of claim 3,
    상기 출력신호 수신단계 이후에 수행되며, 상기 출력신호로부터 상기 제1입력신호로부터 변형된 제1출력신호와 상기 제2입력신호로부터 변형된 제2출력신호를 분해하는 출력신호 분해단계;를 더 포함하는 것을 특징으로 하는 파우치형 이차전지의 내부균열 비파괴 검사방법.The output signal decomposition step of decomposing the first output signal transformed from the first input signal and the second output signal transformed from the second input signal from the output signal is performed after the step of receiving the output signal; further comprising A method for non-destructive testing of internal cracks in pouch-type secondary batteries, characterized in that
  5. 제4항에 있어서,5. The method of claim 4,
    상기 제1주파수는 부분균열의 존재 여부를 판단하는데 이용되고, 상기 제1주파수보다 고주파인 상기 제2주파수는 완전균열의 존재 여부를 판단하는데 이용되며,The first frequency is used to determine whether a partial crack exists, and the second frequency, which is higher than the first frequency, is used to determine whether a complete crack exists,
    상기 제1신호패턴 검출단계는 상기 제1출력신호와 상기 기준신호를 비교하여 상기 제1차이값을 검출하고,The first signal pattern detection step detects the first difference value by comparing the first output signal with the reference signal,
    상기 제2신호패턴 검출단계는 상기 제2출력신호와 상기 기준신호를 비교하여 상기 제2차이값을 검출하는 것을 특징으로 하는 파우치형 이차전지의 내부균열 비파괴 검사방법.The second signal pattern detecting step compares the second output signal with the reference signal to detect the second difference value.
PCT/KR2022/006240 2021-03-30 2022-05-02 Non-destructive inspection method for internal crack in pouch-type secondary battery WO2022235032A1 (en)

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