Apparatus for detecting defects of battery cell and method for detecting defects of battery cell

Abstract

An apparatus for detecting a defect of a battery cell according to one embodiment of the present disclosure comprises: a magnetic field measurement unit for measuring a magnetic field generated by a current flowing in the battery cell; the supporting part is used for supporting the magnetic field measuring part; and a mounting portion on which the battery cell is placed, in which the magnetic field measuring portion includes: a first measuring member for scanning one surface of the battery cell; a second measuring member for scanning the other surface of the battery cell facing the one surface; and a third measurement member coupled between the first measurement member and the second measurement member, and the first measurement member, the second measurement member, and the third measurement member are integrated as a whole.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the priority of Korean Patent Application No. 10-2022-0180417 filed on December 21, 2022, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0002] The present disclosure relates to a device for detecting defects in a battery cell and a method for detecting defects in a battery cell. More specifically, the present disclosure relates to a device for detecting defects in a battery cell and a detection method thereof as follows: the device detects abnormal current in a battery cell, a defective battery cell and / or detects defective parts by applying a 3D magnetic field scanning sensor and determining the abnormal current. Background Art

[0003] X-ray CT is a conventional non-contact, non-destructive analysis method for battery cells that requires a long analysis time, thus making it impossible to perform real-time analysis of various defect causes. In addition, visual inspections such as X-ray CT are not effective for verifying degradation or defects (lithium deposition, tab breakage, etc.) of battery cells, so disassembly analysis is required. In order to overcome the shortcomings of this X-ray CT analysis, research has been conducted to analyze defects by visualizing the current distribution inside the battery cell, however, in the measurement of the induced magnetic field induced by MRI, electromagnetic waves cannot penetrate the battery cell, and it is also difficult to obtain high resolution due to the ferromagnetic materials contained in the battery cell.

[0004] Therefore, it is necessary to develop diagnostic techniques and test methods for diagnosing degradation and defects of battery cells through nondestructive analysis. As a method for detecting such changes, recent research has introduced a technique using magnetic field imaging (MFI) to detect defects through changes in the magnetic field formed during the charging and discharging of the battery cells.

[0005] Figure 1An apparatus 1 for detecting defects of a battery cell according to the prior art is shown. Imaging of the flow of current by MFI measurement is performed on a cross section of the battery cell. In other words, the magnetic field is measured while the current flows through the battery cell, and then the current value is calculated and imaged using the current-magnetic field relationship (Biot-Savart law). However, according to this prior art, the measuring unit is only present on the top surface, so only 2D cross-sectional measurements can be performed on the battery cell. In addition, the magnetic field can only be detected on the surface of the battery cell (i.e., the surface facing the magnetic field detection device), and the magnetic field cannot be detected on the side surface or bottom surface of the battery cell. The magnetic field measurement performed by the apparatus for detecting defects of the battery cell according to the prior art is limited to a 2D cross section, and only the surface current can be observed, so there are limitations in detecting disconnection / foreign objects inside the battery cell. Summary of the invention

[0006] Technical issues

[0007] One object of the present disclosure is to provide an apparatus for detecting defects in a battery cell and a method for detecting defects in a battery cell. Another object of the present disclosure is to provide a technique for sensing abnormal current in a battery cell, particularly in 3D when applying magnetic field imaging techniques. A further object of the present disclosure is to use a more efficient method to calculate abnormal current in a battery cell and determine the abnormal current, thereby more effectively (i.e., faster and more accurately) detecting defects in a battery cell.

[0008] However, the technical problems to be solved by the embodiments of the present disclosure are not limited to the above problems, but can be variously extended within the scope of the technical concept included in the present disclosure.

[0009] Technical Solution

[0010] According to one embodiment of the present disclosure, there is provided an apparatus for detecting defects of a battery cell, the apparatus comprising: a magnetic field measuring portion, the magnetic field measuring portion measuring a magnetic field generated by a current flowing through the battery cell; a supporting portion, the supporting portion supporting the magnetic field measuring portion; and a mounting portion, the battery cell being placed on the mounting portion, wherein the magnetic field measuring portion comprises: a first measuring member, the first measuring member scanning one side of the battery cell; a second measuring member, the second measuring member scanning the other side of the battery cell opposite to the one side; and a third measuring member, the third measuring member being connected between the first measuring member and the second measuring member, and wherein the first measuring member, the second measuring member and the third measuring member are integrated into one body.

[0011] The magnetic field measuring part may include the first, second, and third measuring members, and may simultaneously scan the top, bottom, and side surfaces of the battery cell.

[0012] A third measuring member is provided, and the third measuring member can connect one end of the first measuring member with one end of the second measuring member.

[0013] Two third measuring members are provided, wherein one third measuring member can connect one end of the first measuring member with one end of the second measuring member, and the other third measuring member can connect the other end of the first measuring member with the other end of the second measuring member.

[0014] The mounting portion is a support member having a plate shape on which the battery cell is placed, and includes the support member suspended at a predetermined distance upward from a bottom surface, and the second measuring member may be arranged below the support member.

[0015] The support member may have a low magnetic permeability (μ) so that the influence of the support member on the magnetic field scanning of the second measuring member is minimized.

[0016] The apparatus for detecting defects in a battery cell may further include a processing unit that converts the measured magnetic field data to determine whether there is a defect in the battery cell or to determine a defective location of the battery cell.

[0017] Each of the first, second, and third measuring members has a shape of a bar or a rod, and the magnetic field measuring part may move in a longitudinal direction of the battery cell to scan the battery cell.

[0018] The first measuring member, the second measuring member and the third measuring member may each independently generate magnetic field data.

[0019] A three-dimensional magnetic field vector value may be generated from magnetic field data independently generated by each of the first measurement member, the second measurement member, and the third measurement member.

[0020] The magnetic field data may be a magnetic field image (MFI).

[0021] The types of defects detected above may include at least one of the following: a folded portion of an electrode plate of the battery cell; a disconnected portion of the electrode plate; a portion where the electrode active material is unevenly coated on the coated portion of the electrode plate; a disconnected portion of an electrode lead or electrode tab of the battery cell; and a portion in which multiple electrode plates stacked therein are misaligned.

[0022] According to another embodiment of the present disclosure, a method for detecting defects in a battery cell is provided, the method comprising the following steps: receiving magnetic field data measured by a magnetic field measuring unit; deriving a three-dimensional magnetic field vector value for each of a plurality of sub-regions of the battery cell from the received magnetic field data; converting the derived magnetic field vector value into a three-dimensional induced current vector value; determining whether the induced current value corresponds to a current value within a normal range by comparing the induced current vector value with a predetermined current vector threshold; and detecting whether there is a defect in the battery cell or detecting a defective portion of the battery cell.

[0023] The step of converting the derived magnetic field vector value into an induced current vector value may comprise the step of multiplying the induced current vector value by a correction factor.

[0024] The step of determining whether the induced current value corresponds to a current value within a normal range may include the following steps: if the induced current vector value is greater than a predetermined upper current vector threshold, or if the induced current vector value is less than a predetermined lower current vector threshold, determining that there is a current abnormality in the battery cell.

[0025] Beneficial effects

[0026] According to the present disclosure, when the magnetic field imaging technology is applied to detect defects of battery cells, the battery cells can be inspected more accurately from multiple angles, thereby making it possible to ensure the reliability of the quality of the produced battery cells.

[0027] Furthermore, a high-reliability preliminary inspection can be performed at the battery cell level, so that when inspecting a battery module or battery pack, the inefficiency problem of the entire battery module or battery pack being discarded due to one defective battery cell can also be solved.

[0028] Effects obtainable by the present disclosure are not limited to the above-mentioned effects, but other additional effects not mentioned herein will be clearly understood by those skilled in the art from the description of the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A device for detecting defects of a battery cell according to the prior art is shown.

[0030] Figure 2 is a perspective view schematically showing an apparatus for detecting defects of a battery cell according to an embodiment of the present disclosure.

[0031] Figure 3 yes Figure 2 A front view of a device for detecting defects of a battery cell.

[0032] Figure 4 is an example of a magnetic field image generated by the MFI method.

[0033] Figure 5 An example of the final current vector value (I) is shown.

[0034] Figure 6 Examples of defect types in battery cells are shown. DETAILED DESCRIPTION

[0035] Hereinafter, the embodiments disclosed in the present specification will be described in detail with reference to the accompanying drawings, however, the same or similar constituent elements are given the same or similar reference numerals, and their repeated description will be omitted.

[0036] The suffixes "component" and / or "unit" of the constituent elements used in the following description are only given or used for the convenience of describing this specification, and these suffixes themselves do not have a meaning or function of distinguishing one from another. In addition, terms such as "...component" or "...unit" described in this specification refer to a unit for performing at least one function or operation, which can be implemented by hardware, by software, or by a combination of hardware and software.

[0037] In the following description of the present disclosure, if it is determined that a detailed description of the known functions and structures incorporated herein may make the subject matter of the present disclosure unclear, the detailed description thereof will be omitted. In addition, the drawings are only for facilitating the understanding of the embodiments disclosed in this specification, but the technical concepts disclosed herein are not limited by the drawings, but should be understood to include all changes, equivalents and substitutes contained in the spirit and scope of the present disclosure.

[0038] In the present specification, terms such as “including” or “having” are intended to specify the presence of features, numbers, steps, operations, components, parts, or a combination thereof described in the specification, but it should be understood that this does not preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or a combination thereof.

[0039] Hereinafter, an apparatus 100 for detecting defects of a battery cell according to an embodiment of the present disclosure will be described.

[0040] Figure 2 is a perspective view schematically illustrating an apparatus 100 for detecting defects of a battery cell according to an embodiment of the present disclosure. Figure 3 yes Figure 2 FIG. 1 is a front view of an apparatus 100 for detecting defects of a battery cell.

[0041] According to an embodiment of the present disclosure, the device 100 for detecting defects of a battery cell generally includes: a magnetic field measuring part 110; a supporting part 120, to which the magnetic field measuring part 110 is connected to fix and support the magnetic field measuring part 110; a mounting part 130, on which the battery cell 10 is placed; and a processing unit 140 and / or a storage unit 140.

[0042] The magnetic field measuring part 110 is arranged near the battery cell 10 and is spaced apart from the battery cell 10 by a predetermined distance. A current is applied to the battery cell 10, and the current flows through the battery cell 10 between the positive electrode lead 12 and the negative electrode lead 12 of the battery cell 10, thereby inducing a magnetic field. The magnetic field measuring part 110 measures the magnetic field induced by the current flowing through the battery cell 10. The body 11 of the battery cell 10 may be scanned, and the body 11, the positive electrode lead 12 and the negative electrode lead 12, and the positive electrode tab and the negative electrode tab may also be scanned as a whole.

[0043] In the apparatus 100 for detecting defects of a battery cell according to an embodiment of the present disclosure, the magnetic field measuring unit 110 is capable of scanning the battery cell 10 in three dimensions at a time. For example, the magnetic field measuring unit 110 may have a “ More specifically, the magnetic field measuring unit 110 includes: a first measuring member 111 for scanning one side of the battery cell 10, a second measuring member 112 for scanning the other side of the battery cell 10 opposite to the one side, and one or two third measuring members 113 connected between the first measuring member 111 and the second measuring member 112.

[0044] The first measuring member 111 and the second measuring member 112 may be arranged in parallel with each other. In addition, a third measuring member 113 may be connected between one end of the first measuring member 111 and one end of the second measuring member 112. Thus, the magnetic field measuring unit 110 has a “ Alternatively, the two third measuring members 113 may be respectively coupled between one end of the first measuring member 111 and one end of the second measuring member 112 and between the other end of the first measuring member 111 and the other end of the second measuring member 112. Therefore, the magnetic field measuring part 110 may have a square shape.

[0045] Each of the first, second, and third measuring members 111 , 112 , and 113 includes a scanning unit that scans a magnetic field on a surface facing the battery cell 10 .

[0046] The first measuring member 111, the second measuring member 112 and the third measuring member 113 are integrated into one body. More specifically, the first measuring member 111, the second measuring member 112 and the third measuring member 113 may be formed in one piece, or may be manufactured separately and then connected together. In addition, each of the first measuring member 111, the second measuring member 112 and the third measuring member 113 may have the shape of a rod or a bar. Alternatively, each of the first measuring member 111, the second measuring member 112 and the third measuring member 113 may have the shape of a plate. In the former case, the magnetic field measuring part 110 may scan the magnetic field of the battery cell 10 while moving along the longitudinal direction of the battery cell 10. In the latter case, if each of the first measuring member 111, the second measuring member 112 and the third measuring member 113 can cover the battery cell 10, it is possible to scan the magnetic field of the battery cell 10 at one time without moving the magnetic field measuring part 110.

[0047] For example, the first measuring member 111 may scan the top surface of the battery cell 10, and the second measuring member 112 may scan the bottom surface of the battery cell 10. In addition, the third measuring member 113 may scan both sides or one side of the battery cell 10. However, the present disclosure is not limited to the above case, and when scanning the upright battery cell 10, various modifications and changes may be made, for example, the first measuring member 111 and the second measuring member 112 may scan both sides of the battery cell 10, respectively, and the third measuring member 113 may scan the top surface or the bottom surface of the battery cell 10.

[0048] In addition, the first measuring member 111, the second measuring member 112 and the third measuring member 113 simultaneously scan the battery cell 10, wherein the first measuring member 111, the second measuring member 112 and the third measuring member 113 each independently generate magnetic field data from the battery cell 10. For the magnetic field data, refer to the content described later.

[0049] The support part 120 is connected and fixed to the magnetic field measuring part 110 to support the magnetic field measuring part 110. Figure 3 In the exemplary embodiment of FIG. 1 , a case where the support portion 120 is connected to the first measurement member 111 is illustrated, but the present disclosure is not limited thereto. Instead, the support portion 120 may be connected to at least one of the first measurement member 111 , the second measurement member 112 , and the third measurement member 113 .

[0050] When the magnetic field measuring part 110 scans the battery cell 10 while moving, the supporting part 120 may further include a driving member. By the driving member included in the supporting part 120, the magnetic field measuring part 110 may scan the battery cell 10 while moving in the longitudinal direction.

[0051] The battery cell 10 is mounted on a mounting portion 130 including a support member 131. The mounting portion 130 generally includes a support member 131, a pillar member 132, and a table 133. The battery cell 10 is placed on the plate-shaped support member 131. The support member 131 can be suspended and positioned at a predetermined distance upward from the bottom surface (e.g., the table 133) by the pillar member 132. The second measuring member 112 of the magnetic field measuring unit 110 is arranged on the bottom surface of the support member 131. Thus, not only the first measuring member 111 can be arranged on one side of the battery cell 10, but also the second measuring member 112 opposite thereto can be arranged on the other side of the battery cell 10 opposite to the one side.

[0052] Meanwhile, the support member 131 is positioned between the second measuring member 112 of the magnetic field measuring part 110 and the battery cell 10. The support member 131 has low magnetic permeability (μ) so that magnetic field scanning of the second measuring member 112 is not affected by the support member 131 or such an effect is minimized.

[0053] Data containing the magnetic field value of the battery cell 10 measured by scanning at the magnetic field measuring section 110 (hereinafter referred to as "magnetic field data") can be transmitted to the processing unit 140 and / or the storage unit 140 by wired or wireless means. The processing unit 140 and / or the storage unit 140 can be provided separately, or can be integrated into one device. The processing unit 140 and / or the storage unit 140 can be, for example, a computer, a laptop computer, or various control devices suitable for implementing the environment and corresponding processes of the present invention.

[0054] The magnetic field data scanned by the magnetic field measuring unit 110 may be transmitted in a wired manner through a data transmission line (not shown) provided on the support unit 120 connected to the magnetic field measuring unit 110. Alternatively, the magnetic field measuring unit 110 or the support unit 120 connected thereto may include a separate transceiver (not shown) to wirelessly transmit the magnetic field data scanned by the magnetic field measuring unit 110 in real time (for example, by repeating the following method: scanning a certain part of the battery cell 10 and transmitting the magnetic field data), or transmit after the entire scan is completed.

[0055] In addition, the magnetic field data transmitted from the magnetic field measuring section 110 may be the magnetic field value itself, or may be a magnetic field image generated by the MFI method (for example, see Figure 4 ). Alternatively, the magnetic field data transmitted from the magnetic field measurement unit 110 is the magnetic field value itself, and the processing unit 140 can generate a magnetic field image using the MFI method. The unit of the magnetic field value is T, for example.

[0056] Regarding the processing unit 140 and / or the storage unit 140 , refer to the method for detecting defects of a battery cell described later.

[0057] Next, a method for detecting a defect of a battery cell according to an embodiment of the present disclosure will be described. The method for detecting a defect of a battery cell is performed in the processing unit 140 of the device 100 for detecting a defect of a battery cell. In addition, data may be sent / received in the storage unit 140 and stored in the storage unit 140. That is, the processing unit 140 may cooperate with the storage unit 140 to perform the method for detecting a defect of a battery cell.

[0058] First, step (S110) is performed: receiving magnetic field data from the magnetic field measuring unit 110 to the processing unit 140 and / or the storage unit 140. Regarding the transmission of magnetic field data from the magnetic field measuring unit 110, refer to the above-mentioned part.

[0059] In addition, step (S120) is performed: a magnetic field vector value is derived for each of the multiple sub-regions of the battery cell from the received magnetic field data. The processing unit 140 generates a three-dimensional magnetic field vector value B=(B x , B y , B z ). These three-dimensional magnetic field vector values ​​are magnetic field vector values ​​at the x-axis position, y-axis position, and z-axis position of the battery cell 10. The area of ​​the battery cell 10 may be divided into a plurality of sub-areas in three dimensions, and a magnetic field vector value B may be generated for each area. In the apparatus 100 for detecting defects of a battery cell of the present disclosure, since the magnetic field measuring unit 110 scans the battery cell 10 in three dimensions, such a three-dimensional magnetic field vector value B can be generated based on the magnetic field data received from the magnetic field measuring unit 110.

[0060] Regarding the generation of the magnetic field vector value B, for example, each magnetic field image generated from the first measurement member 111, the second measurement member 112, and the third measurement member 113 of the magnetic field measurement unit 110 may be divided into Figure 4 The grid shape shown, then, the three-dimensional vector value B can be derived from the corresponding magnetic field image value of each region.

[0061] In addition, for example, the three-dimensional magnetic field vector value B can be generated by a method of weighting, summing and correcting the magnetic field data received from the first measuring member 111, the second measuring member 112 and the third measuring member 113 of the magnetic field measuring unit 110. For example, since the first measuring member 111 and the second measuring member 112 are located on two opposite surfaces of the battery cell 10, the three-dimensional magnetic field vector value B can be derived by combining them.

[0062] However, the present disclosure is not limited to the above case, but any method capable of generating a three-dimensional magnetic field vector value B = (B x , By ,B z ) methods are sufficient.

[0063] Next, a step (S130) is performed: converting the derived magnetic field vector value into induced current data. Since it is calculated from the magnetic field vector value, the induced current data becomes an induced current vector value (hereinafter referred to as "current vector value").

[0064] The three-dimensional magnetic field vector value B at the x-axis position, y-axis position and z-axis position of the battery cell 10 = (B x , B y , B z ) is converted into a current vector value I0 = (I 0x , I 0y , I 0z ). That is, the converted current value refers to the current value flowing at the corresponding x-axis position, y-axis position, and z-axis position of the battery cell 10. The process of converting the magnetic field into current follows the Biot-Savart Law of the following mathematical equation 1.

[0065] [Mathematical equation 1]

[0066] Wherein, B is the magnetic field, I is the current, μ0 is the magnetic permeability in free space, and r is the diameter (ie, the distance from the corresponding area of ​​the battery cell 10 to the magnetic field measuring part 110 ).

[0067] In addition, when converting the corresponding magnetic field into current, the final current vector value I can be derived by multiplying the correction coefficient (α). This is a coefficient for correcting the error between the current value actually flowing in the relevant area of ​​the battery cell 10 and the current value derived from the magnetic field due to factors such as related equipment or the surrounding environment. If correction is not required, the correction coefficient can be set to α = 1.

[0068] [Mathematical equation 2] I = (I x , I y , I z ) = αI0

[0069] Figure 5 An example of a final current vector value I is shown.

[0070] In addition, the above process is performed according to the magnetic field data transmitted from the first measuring member 111, the second measuring member 112 and the third measuring member 113, respectively, to derive I D1 ,I D2 ,I D3. I D1 ,I D2 ,I D3 Currents derived from the magnetic field data of the first measurement member 111 , the second measurement member 112 , and the third measurement member 113 are respectively shown in sequence.

[0071] Next, a step (S140) is performed: determining whether the induced current value corresponds to a current value within a normal range. By comparing the derived induced current vector value with a current vector threshold, it is possible to determine whether an abnormal current exists.

[0072] By placing the corresponding I D1 ,I D2 ,I D3 The current threshold I of a normal battery cell TH Compare to determine whether there is abnormal current. That is, if it exceeds the current threshold I of a normal battery cell TH , it can be determined that the current is abnormal. In addition, the current threshold of a normal battery cell can be set as the upper current threshold I TH-high and / or lower current threshold I TH-low In this case, if I is greater than the upper current threshold I TH-high Or less than the lower current threshold I TH-low , it can be determined as current abnormality. In addition, by changing the current threshold I TH To set the corresponding I D1 ,I D2 ,I D3 .

[0073] Next, step (S150) is performed: a defect in the battery cell 10 is detected. For example, if it is determined in step (S140) that it is an abnormal current, it can be determined that the corresponding battery cell 10 is defective. In addition, for example, since the battery cell 10 is divided into a plurality of sub-regions and a current vector value I is derived for each sub-region, the sub-region in which the abnormal current is detected can be determined as a defective region.

[0074] For reference, defects of the battery cell 10 may include, for example: folding of the electrode plate 11a or disconnection of the electrode plate 11a (e.g., perforation or tearing, etc.); poor coating of the electrode active material on the coated portion of the electrode plate 11a; disconnection of the electrode tab or electrode lead; or misalignment of a plurality of electrode plates stacked inside the battery cell 10. As an example, Figure 6 A state in which the electrode plate is folded at the folded portion P is shown.

[0075] When the defect of the battery cell 10 is detected using the apparatus 100 for detecting a defect of the battery cell and the method for detecting a defect of the battery cell according to the present disclosure, it is possible to quickly determine whether the battery cell 10 and / or the connection portion of the battery cell 10 has a defect, compared to the prior art. At the same time, it is possible to more accurately determine whether the battery cell 10 and / or the connection portion of the battery cell 10 has a defect. Thus, the reliability of the quality of the produced battery cells can be ensured.

[0076] Although the present invention has been described in detail above in conjunction with its preferred embodiments, those skilled in the art will appreciate that the scope of the present disclosure is not limited thereto, but that various modifications and improvements may be made to these embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

[0077] [Explanation of Reference Numerals]

[0078] 10: Battery Cell

[0079] 11: Main body

[0080] 12: Electrode lead

[0081] 100: Device for detecting defects in battery cells

[0082] 110: Magnetic field measurement unit

[0083] 111: First measuring member

[0084] 112: Second measuring member

[0085] 113: The third measuring member

[0086] 120: Support

[0087] 130: Installation

[0088] 131: Supporting member

[0089] 132: Support component

[0090] 133: Countertop

[0091] 140: Processing unit / storage unit

Claims

1. A device for detecting defects of a battery cell, comprising: a magnetic field measuring unit that measures a magnetic field generated by a current flowing through the battery cell; a supporting portion, the supporting portion supporting the magnetic field measuring portion; as well as a mounting portion on which the battery cell is placed, The magnetic field measuring unit includes: a first measuring member that scans one side of the battery cell; a second measuring member that scans the other side of the battery cell opposite to the one side; and a third measuring member that is connected between the first measuring member and the second measuring member, and Wherein, the first measuring member, the second measuring member and the third measuring member are integrated into one.

2. The device for detecting defects of a battery cell according to claim 1, wherein: The magnetic field measuring part includes the first, second, and third measuring members, and simultaneously scans a top surface, a bottom surface, and a side surface of the battery cell.

3. The device for detecting defects of a battery cell according to claim 1, wherein: A third measuring member is provided, and the third measuring member connects one end of the first measuring member and one end of the second measuring member.

4. The device for detecting defects of a battery cell according to claim 1, wherein: Two third measuring members are provided, wherein one third measuring member connects one end of the first measuring member with one end of the second measuring member, and the other third measuring member connects the other end of the first measuring member with the other end of the second measuring member.

5. The device for detecting defects of a battery cell according to claim 1, wherein: The mounting portion is a support member having a plate shape on which the battery cell is placed, and the mounting portion includes the support member suspended at a predetermined distance upward from a bottom surface, and The second measuring member is arranged below the supporting member.

6. The device for detecting defects of a battery cell according to claim 1, wherein: The support member has a low magnetic permeability (μ) so that the influence of the support member on the magnetic field scanning of the second measuring member is minimized.

7. The device for detecting defects of a battery cell according to claim 1, The device also includes a processing unit, which converts the measured magnetic field data to determine whether there is a defect in the battery cell or to determine the defective location of the battery cell.

8. The device for detecting defects of a battery cell according to claim 1, wherein: Each of the first measuring member, the second measuring member, and the third measuring member has a shape of a bar or a rod, and The magnetic field measuring part moves in a longitudinal direction of the battery cell to scan the battery cell.

9. The device for detecting defects of a battery cell according to claim 1, wherein: The first measuring member, the second measuring member and the third measuring member each independently generate magnetic field data.

10. The device for detecting defects of a battery cell according to claim 9, wherein: A three-dimensional magnetic field vector value is generated from the magnetic field data independently generated by each of the first measurement member, the second measurement member, and the third measurement member.

11. The device for detecting defects of a battery cell according to claim 1, wherein: The magnetic field data is a magnetic field image (MFI).

12. The device for detecting defects of a battery cell according to claim 1, wherein: The types of defects detected include at least one of the following: a folded portion of an electrode plate of the battery cell; a disconnected portion of the electrode plate; a portion where an electrode active material is unevenly applied to a coating portion of the electrode plate; a disconnected portion of an electrode lead or an electrode tab of the battery cell; and a portion in which a plurality of stacked electrode plates are misaligned.

13. A method for detecting defects in a battery cell, the method comprising the following steps: receiving magnetic field data measured by a magnetic field measuring unit; deriving a three-dimensional magnetic field vector value for each of a plurality of sub-regions of the battery cell from the received magnetic field data; converting the derived magnetic field vector value into a three-dimensional induced current vector value; determining whether the induced current value corresponds to a current value within a normal range by comparing the induced current vector value with a predetermined current vector threshold; as well as Detect whether there is a defect in the battery cell or detect the defective part of the battery cell.

14. The method for detecting defects of a battery cell according to claim 13, wherein: The step of converting the derived magnetic field vector value into an induced current vector value comprises the step of multiplying the induced current vector value by a correction factor.

15. The method for detecting defects of a battery cell according to claim 13, wherein: The step of determining whether the induced current value corresponds to a current value within a normal range includes the following steps: if the induced current vector value is greater than a predetermined upper current vector threshold, or if the induced current vector value is less than a predetermined lower current vector threshold, determining that there is a current abnormality in the battery cell.

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