Battery cell defect detection device and battery cell defect detection method

Abstract

A battery cell defect detection device according to one embodiment of the present invention includes a magnetic field measurement unit that measures a magnetic field generated by a current flowing through a battery cell; a support unit that supports the magnetic field measurement unit; and a mounting unit on which the battery cell is placed, wherein the magnetic field measurement unit includes a first measurement member that scans one side of the battery cell, a second measurement member that scans the other side of the battery cell opposite to the one side, and a third measurement member that is 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.

Description

[Technical Field]

[0001] [Cross-reference of related applications] This application claims priority under Korean Patent Application No. 10-2022-0180417 dated December 21, 2022, and all content disclosed in the said Korean Patent Application is incorporated herein as part of this specification.

[0002] The present invention relates to a battery cell defect detection device and a battery cell defect detection method, and more specifically, to a battery cell defect detection device and method that detects abnormal currents and defective battery cells and / or defective locations through the application of a 3D magnetic field scanning sensor and abnormal current determination. [Background technology]

[0003] Conventional non-contact, non-destructive analysis methods for battery cells, such as X-ray CT, require long analysis times, making real-time analysis of various defect causes impossible. Furthermore, visual detection methods like X-ray CT are ineffective for verifying battery cell degradation and defects (lithium deposition, tab breakage, etc.), requiring decomposition analysis. To overcome these shortcomings of X-ray CT, research has progressed on analyzing defects through visualization of the internal current distribution of battery cells. However, MRI-induced magnetic field measurement has been difficult to achieve high resolution due to the inability of electromagnetic waves to penetrate battery cells and the presence of ferromagnetic materials within the battery cells.

[0004] Therefore, there is a need to develop diagnostic techniques and testing methods for cell degradation and defects through non-destructive analysis. As a way to detect such changes, research has recently been progressing on techniques that utilize magnetic field imaging (MFI) to detect defects through changes in the magnetic field formed during the charging and discharging of battery cells.

[0005] Figure 1 shows a conventional battery cell defect detection device 1. It performs imaging of the current flow in the cross-section of the battery cell using MFI measurement. That is, after measuring the magnetic field while current is flowing through the battery cell, the current value is calculated using the current-magnetic field relationship (Biot-Savart Law) and then visualized. However, with this conventional technology, the measurement unit is located only on the top surface, and only 2D cross-sectional measurement of the battery cell is possible. Therefore, only the magnetic field detection of the surface of the battery cell (i.e., the surface facing the magnetic field detection device) is possible, and magnetic field detection of the sides or bottom of the battery cell is impossible. Conventional battery cell defect detection devices have limitations in detecting internal defects such as broken wires or foreign objects because magnetic field measurement is limited to the 2D cross-section and only the surface current is observed. [Overview of the project] [Problems that the invention aims to solve]

[0006] This invention provides an apparatus and a method for detecting defects in battery cells, and aims to provide a technology for sensing abnormal currents within battery cells, particularly by applying magnetic field imaging techniques in 3D. The aim is to detect defects within battery cells more effectively, i.e., more quickly and accurately, through more efficient methods for calculating and determining abnormal currents within battery cells.

[0007] However, the problems that the embodiments of the present invention aim to solve are not limited to those described above, and can be extended in various ways within the scope of the technical ideas included in the present invention. [Means for solving the problem]

[0008] A battery cell defect detection device according to one embodiment of the present invention includes: a magnetic field measuring unit for measuring a magnetic field generated by an electric current flowing through a battery cell; a support unit for supporting the magnetic field measuring unit; and a mounting unit on which the battery cell is placed, wherein the magnetic field measuring unit 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 opposite to the one surface, and a third measuring member coupled between the first measuring member and the second measuring member, and the first measuring member, the second measuring member, and the third measuring member can be integrated.

[0009] The magnetic field measuring unit can simultaneously scan the top, bottom, and side surfaces of the battery cell using the first measuring member, the second measuring member, and the third measuring member.

[0010] A third measuring member is provided, which can connect one end of the first measuring member and one end of the second measuring member.

[0011] Two third measuring members are provided, one of which connects one end of the first measuring member to one end of the second measuring member, and the other which can connect the other end of the first measuring member to the other end of the second measuring member.

[0012] The mounting portion includes a receiving member having a plate shape on which the battery cell is placed, and which is positioned in the air at a predetermined distance from the bottom surface in the upward direction, and the second measuring member can be positioned below the receiving member.

[0013] In the magnetic field scanning of the second measuring member, the receiving member can have a low magnetic permeability (μ) so as to minimize the influence of the receiving member.

[0014] The system may further include a processing unit that converts the measured magnetic field data to determine whether or not there are defects in the battery cell or the location of any defects in the battery cell.

[0015] Each of the first measuring member, the second measuring member, and the third measuring member is bar-shaped or rod-shaped, and scanning of the battery cell can be performed by moving the magnetic field measuring member in the length direction of the battery cell.

[0016] Each of the first measuring member, the second measuring member, and the third measuring member can individually generate magnetic field data.

[0017] Three-dimensional magnetic field vector values can be generated from the magnetic field data individually generated from each of the first measuring member, the second measuring member, and the third measuring member.

[0018] The magnetic field data may be Magnetic Field Imaging (MFI).

[0019] The types of detected defects may include at least one selected from the group consisting of a bent portion of an electrode plate of the battery cell, a broken portion of the electrode plate, a portion of a coating part of the electrode plate where an electrode active material is unevenly applied, a broken portion of an electrode lead or an electrode tab of the battery cell, and a portion where stacked electrode plates are misaligned.

[0020] The method may comprise the steps of: receiving magnetic field data measured by a magnetic field measurement 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; comparing the induced current vector value with a predetermined current vector threshold to determine whether the induced current value falls within a normal range of current values; and detecting the presence or absence of a defect in the battery cell or a defective portion of the battery cell.

[0021] The step of converting the derived magnetic field vector value into the induced current vector value may include the step of multiplying the induced current vector value by a correction coefficient.

[0022] The step of determining whether the induced current value falls within the normal range may include determining that there is a current abnormality in the battery cell if the induced current vector value is greater than a predetermined upper limit current vector threshold or if the induced current vector value is less than a predetermined lower limit current vector threshold. [Effects of the Invention]

[0023] According to the present invention, when detecting defects in battery cells by applying magnetic field imaging techniques, it is possible to inspect the battery cells more precisely from multiple angles, thereby ensuring reliability regarding the quality of the battery cells produced.

[0024] At the same time, since reliable pre-inspection is possible at the battery cell level, the inefficiency of having to discard an entire battery module or battery pack due to a single defective cell, which occurs when inspecting at the battery module or battery pack level, can be resolved.

[0025] The 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 claims. [Brief explanation of the drawing]

[0026] [Figure 1] This shows a conventional battery cell defect detection device. [Figure 2] This is a schematic perspective view showing a battery cell defect detection device according to one embodiment of the present invention. [Figure 3] Figure 2 is a front view of the battery cell defect detection device. [Figure 4] This is an example of a magnetic field image generated using the MFI (Multi-Film Injection) method. [Figure 5] An example of the final current vector value I is shown. [Figure 6] Here are some examples of battery cell defects. [Modes for carrying out the invention]

[0027] The embodiments disclosed herein will now be described in detail with reference to the attached drawings, but identical or similar components will be given the same or similar reference numerals, and redundant explanations will be omitted.

[0028] The suffixes "component" and / or "part" used with respect to components in the following description are added or used interchangeably solely for the sake of ease of specification preparation and do not have any distinct meaning or role in themselves. Furthermore, terms such as "...component" and "...part" used in the specification refer to a unit that processes at least one function or operation, which can be implemented in hardware, software, or a combination of hardware and software.

[0029] Furthermore, in describing the embodiments disclosed herein, if a specific description of the relevant prior art is deemed to detract from the essence of the embodiments disclosed herein, such detailed description will be omitted. The accompanying drawings are provided to facilitate understanding of the embodiments disclosed herein and should not be understood as limiting the technical ideas disclosed herein, but rather as including all modifications, equivalents, or substitutions that fall within the concept and technical scope of the present invention.

[0030] In this application, terms such as “including” should be understood to indicate the presence of features, figures, steps, actions, components, parts, or combinations thereof described in the specification, and not to preemptively exclude the possibility of the presence or addition of one or more other features, figures, steps, actions, components, parts, or combinations thereof.

[0031] The following describes a battery cell defect detection device 100 according to one embodiment of the present invention.

[0032] Figure 2 is a schematic perspective view of a battery cell defect detection device 100 according to one embodiment of the present invention. Figure 3 is a front view of the battery cell defect detection device 100 shown in Figure 2.

[0033] A battery cell defect detection device 100 according to one embodiment of the present invention includes a magnetic field measuring unit 110, a support unit 120 to which the magnetic field measuring unit 110 is connected and which fixes and supports the magnetic field measuring unit 110, a mounting unit 130 on which the battery cell 10 is placed, and a processing unit 140 and / or a storage unit 140.

[0034] The magnetic field measuring unit 110 is positioned near the battery cell 10 at a predetermined distance from the battery cell 10. When current is applied to the battery cell 10, current flows through the battery cell 10 with the positive electrode lead 12 and the negative electrode lead 12 in between, and a magnetic field is induced from this current. The magnetic field measuring unit 110 measures the magnetic field induced from the current flowing through the battery cell 10. The main body 11 of the battery cell 10 can be scanned, or the main body 11, the positive electrode lead 12 and the negative electrode lead 12, and the positive electrode tab and the negative electrode tab can be scanned as a whole.

[0035] In a battery cell defect detection device 100 according to one embodiment of the present invention, the magnetic field measuring unit 110 can scan the battery cell 10 in three dimensions at once. The magnetic field measuring unit 110, for example, [ka] It can have a letter shape or a rectangular shape. More specifically, the magnetic field measuring unit 110 includes a first measuring member 111 that scans one surface of the battery cell 10, a second measuring member 112 that scans the other surface of the battery cell 10 opposite to the first surface, and one or two third measuring members 113 coupled between the first measuring member 111 and the second measuring member 112.

[0036] The first measuring member 111 and the second measuring member 112 can be arranged parallel to each other. Furthermore, a third measuring member 113 can be coupled between one end of the first measuring member 111 and one end of the second measuring member 112. This allows the magnetic field measuring unit 110 to... [ka] It has a rectangular shape. Alternatively, the two third measuring members 113 can be connected between one end of the first measuring member 111 and one end of the second measuring member 112, respectively, and also between the other end of the first measuring member 111 and the other end of the second measuring member 112. This allows the magnetic field measuring unit 110 to have a rectangular shape.

[0037] Each of the first measuring member 111, the second measuring member 112, and the third measuring member 113 includes a scanner unit that scans the magnetic field on the surface facing the battery cell 10.

[0038] The first measuring member 111, the second measuring member 112, and the third measuring member 113 are integrated into one. More specifically, the first measuring member 111, the second measuring member 112, and the third measuring member 113 may be formed as a single unit, or they may be individually manufactured and joined together. Also, each of the first measuring member 111, the second measuring member 112, and the third measuring member 113 may be in the shape of a bar or rod. Alternatively, each of the first measuring member 111, the second measuring member 112, and the third measuring member 113 may be in the shape of a plate. In the former case, the magnetic field measuring unit 110 can scan the magnetic field of the battery cell 10 while moving along the length of the battery cell 10. In the latter case, if the first measuring member 111, the second measuring member 112, and the third measuring member 113 are each capable of covering the battery cell 10, the magnetic field of the battery cell 10 can be scanned at once without moving the magnetic field measuring unit 110.

[0039] For example, the first measuring member 111 can scan the top surface of the battery cell 10, and the second measuring member 112 can scan the bottom surface of the battery cell 10. Furthermore, the third measuring member 113 can scan both sides or one side of the battery cell 10. However, the present invention is not limited to the above, and various modifications and changes are possible, such as when scanning the battery cell 10 in an upright position, allowing the first measuring member 111 and the second measuring member 112 to scan both sides of the battery cell 10, and allowing the third measuring member 113 to scan the top or bottom surface of the battery cell 10.

[0040] Furthermore, the first measuring member 111, the second measuring member 112, and the third measuring member 113 simultaneously scan the battery cell 10, and each of them individually generates magnetic field data from the battery cell 10. For details regarding the magnetic field data, please refer to the description below.

[0041] A support portion 120 is connected to and fixed to the magnetic field measuring unit 110 so as to support the magnetic field measuring unit 110. In the example shown in Figure 3, the support portion 120 is connected to the first measuring member 111, but the present invention is not limited thereto, and the support portion 120 can be connected to at least one of the first measuring member 111, the second measuring member 112, and the third measuring member 113.

[0042] When the magnetic field measuring unit 110 scans the battery cell 10 while moving it, the support unit 120 may further include a drive member. The drive member included in the support unit 120 allows the magnetic field measuring unit 110 to scan the battery cell 10 while moving it in the longitudinal direction.

[0043] The battery cell 10 is mounted on a mounting section 130 which includes a receiving member 131. The mounting section 130 broadly includes the receiving member 131, a column member 132, and a table 133. The battery cell 10 is placed on the plate-shaped receiving member 131. The receiving member 131 can be positioned in the air at a predetermined distance above its bottom surface (e.g., the table 133) by the column member 132. The second measuring member 112 of the magnetic field measuring section 110 is positioned on the lower surface of the receiving member 131. This allows the first measuring member 111 to be positioned on one side of the battery cell 10, as well as the second measuring member 112 to be positioned on the other side of the battery cell 10 opposite to the first measuring member 111.

[0044] On the other hand, a receiving member 131 is positioned between the second measuring member 112 of the magnetic field measuring unit 110 and the battery cell 10. The receiving member 131 has a low magnetic permeability (μ) so that the magnetic field scanning of the second measuring member 112 is not affected by the receiving member 131, or the effect is minimized.

[0045] Data including the magnetic field value of the battery cell 10 measured by scanning with the magnetic field measuring unit 110 (hereinafter referred to as "magnetic field data") is transmitted by wired or wireless connection to the processing unit 140 and / or storage unit 140. The processing unit 140 and / or storage unit 140 may be provided separately or integrated into a single device. The processing unit 140 and / or storage unit 140 may be, for example, a computer, a laptop computer, or various control devices applicable to the environment and process in which the present invention is implemented.

[0046] The magnetic field data scanned by the magnetic field measuring unit 110 can also be transmitted by wire 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 data scanned by the magnetic field measuring unit 110 can be transmitted wirelessly in real time (for example, by repeatedly scanning a certain portion of the battery cell 10 and transferring the magnetic field data) or after the scanning is completed.

[0047] Furthermore, the magnetic field data transmitted from the magnetic field measurement unit 110 may be the magnetic field value itself, or it may be a magnetic field image generated using the MFI method (see, for example, Figure 4). Alternatively, the magnetic field data transmitted from the magnetic field measurement unit 110 may be the magnetic field value itself, and the processing unit 140 may generate a magnetic field image using the MFI method. The unit of the magnetic field value is, for example, T.

[0048] For the processing unit 140 and / or storage unit 140, refer to the battery cell defect detection method described later.

[0049] The following describes a battery cell defect detection method according to one embodiment of the present invention. The battery cell defect detection method is performed in the processing unit 140 of the battery cell defect detection device 100. Data transmission, reception, and storage can be performed in the storage unit 140. In other words, the processing unit 140 can perform the battery cell defect detection method in conjunction with the storage unit 140.

[0050] First, the magnetic field measurement unit 110 receives magnetic field data in the processing unit 140 and / or storage unit 140 (S110). For details on the transmission of magnetic field data from the magnetic field measurement unit 110, please refer to the section described above.

[0051] Furthermore, a step (S120) is performed to derive magnetic field vector values ​​for each of the multiple sub-regions of the battery cell from the received magnetic field data. The processing unit 140 derives a three-dimensional magnetic field vector value B=(B) from the magnetic field data received from the magnetic field measurement unit 110.x B y B z The three-dimensional magnetic field vector values ​​are the magnetic field vector values ​​at the x-axis, y-axis, and z-axis positions of the battery cell 10. The region of the battery cell 10 can be divided into multiple sub-regions in three dimensions, and magnetic field vector values ​​B can be generated for each region. The battery cell defect detection device 100 of the present invention has a magnetic field measuring unit 110 that scans the battery cell 10 in three dimensions, so it is possible to generate such three-dimensional magnetic field vector values ​​B from the magnetic field data received from the magnetic field measuring unit 110.

[0052] For example, to generate the magnetic field vector value B, the magnetic field images generated by the first measuring member 111, the second measuring member 112, and the third measuring member 113 of the magnetic field measuring unit 110 can be divided into a grid as shown in Figure 4, and then a three-dimensional vector value B can be derived from the magnetic field image value in each region.

[0053] Furthermore, a three-dimensional magnetic field vector value B can be generated by weighting and summing 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, and correcting the result. For example, since the first measuring member 111 and the second measuring member 112 are located on opposite sides of the battery cell 10, they can be combined to derive a three-dimensional magnetic field vector value B.

[0054] However, the present invention is not limited to the above, and the three-dimensional magnetic field vector value B = (B x B y B z Any method that can generate ) is sufficient.

[0055] Next, the derived magnetic field vector value is converted into induced current data (S130). Since it is calculated from the magnetic field vector value, the induced current data becomes the induced current vector value (hereinafter referred to as "current vector value").

[0056] Three-dimensional magnetic field vector value B=(B at the x-axis position, y-axis position, and z-axis position of the battery cell 10 x , B y , B z ), for each component, convert it to current vector value I0=(I 0x , I 0y , I 0z ). That is, the converted current value means the current value flowing at the said x-axis position, y-axis position, and z-axis position of the battery cell 10. The process of converting magnetic field to current follows the Biot-Savart Law of Mathematical Formula 1 below.

Numerical Formula

[0057] Here, B is the magnetic field, I is the current, μ0 is the permeability in free space, and r is the distance (that is, the distance from the said region of the battery cell 10 to the magnetic field measuring instrument 110).

[0058] Furthermore, when converting the magnetic field to current, the final current vector value I can be derived by multiplying a correction coefficient (α). This is a coefficient for correcting the error between the current value actually flowing in the said region of the battery cell 10 and the current value induced from the above magnetic field due to the said device or the surrounding environment, etc. When no correction is required, the correction coefficient may be set to α=1.

Numerical Formula

[0059] FIG. 5 shows an example of the final current vector value I.

[0060] Furthermore, the above process is performed respectively on the magnetic field data respectively transmitted from the first measurement member 111, the second measurement member 112, and the third measurement member 113, to derive I D1 , I D2 , I D3 . I D1 , I D2 , I D3These terms, I, are derived from the first measuring member 111, the second measuring member 112, and the third measuring member 113, respectively.

[0061] Next, a step (S140) is performed to determine whether the induced current value falls within the normal range. The derived induced current vector value can be compared with the current vector threshold to determine whether or not there is an abnormal current.

[0062] Each I D1 , I D2 , I D3 Regarding the current threshold I of a normal cell, TH The presence or absence of a current abnormality is determined by comparing it with the current threshold I of a normal cell. TH If it exceeds this, it can be determined that there is a current abnormality. Also, the current threshold of a normal cell is the upper current threshold I( TH-high ) and / or lower current threshold I( TH-low ) can be set accordingly. In this case, I is the upper limit current threshold I( TH-high If it is greater than ), the lower current threshold I( TH-low If it is smaller than ), it can be determined that there is a current abnormality. Also, each I D1 , I D2 , I D3 For this, the current threshold I TH You can also set them differently.

[0063] Next, a step (S150) is performed to detect defects in the battery cell 10. For example, if an abnormal current is detected in step S140, it can be determined that the battery cell 10 is defective. Alternatively, for example, the battery cell 10 can be divided into multiple sub-regions, and a current vector value I can be derived for each sub-region. In this case, the sub-region where the abnormal current was detected can be determined to be the defective part.

[0064] For reference, possible defects in the battery cell 10 include, for example, bending of the electrode plate 11a, disconnection of the electrode plate 11a (e.g., perforation or tear), poor coating of the electrode active material on the coating portion of the electrode plate 11a, disconnection of the electrode tab or electrode lead, or poor alignment of the multiple electrode plates stacked inside the battery cell 10. Figure 6 shows an example where the electrode plate is bent at the bending portion (P).

[0065] When detecting defects in a battery cell 10 using the battery cell defect detection device 100 and battery cell defect detection method according to the present invention, it is possible to quickly determine the presence or absence of defects in the battery cell 10 and / or the bonding sites of the battery cell 10 compared to the conventional technology. On the other hand, it is possible to more accurately determine the presence or absence of defects in the battery cell 10 and / or the bonding sites of the battery cell 10. This also ensures reliability regarding the quality of the produced battery cells.

[0066] Although preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto. Various modifications and improvements made by those skilled in the art, utilizing the basic concepts of the present invention as defined in the following claims, also fall within the scope of the present invention. [Explanation of Symbols]

[0067] 10 battery cells 11 Main unit 12 electrode leads 100 Battery cell defect detection device 110 Magnetic field measurement section 111 First measuring member 112 Second measuring member 113 Third measuring member 120 Support part 130 Mounting part 131 Receiving member 132 Column members 133 Tables 140 Processing Unit / Storage Unit

Claims

1. A magnetic field measuring unit that measures the magnetic field generated by the current flowing through a battery cell; A support for the magnetic field measuring unit; and The mounting portion on which the battery cell is placed includes, The magnetic field measuring unit 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 opposite to the first surface, and a third measuring member coupled between the first measuring member and the second measuring member. The first measuring member, the second measuring member, and the third measuring member are integrated into a battery cell defect detection device.

2. The battery cell defect detection device according to claim 1, wherein the magnetic field measuring unit simultaneously scans the top surface, bottom surface, and side surface of the battery cell with the first measuring member, the second measuring member, and the third measuring member.

3. A battery cell defect detection device according to claim 1, further comprising a third measuring member connecting one end of the first measuring member and one end of the second measuring member.

4. The battery cell defect detection device according to claim 1, further comprising two third measuring members, one connecting one end of the first measuring member to one end of the second measuring member, and the other connecting the other end of the first measuring member to the other end of the second measuring member.

5. The mounting portion includes a receiving member having a plate shape on which the battery cell is placed, and which is positioned in the air at a predetermined distance from the bottom surface in an upward direction. A battery cell defect detection device according to any one of claims 1 to 4, wherein the second measuring member is positioned below the receiving member.

6. The battery cell defect detection device according to claim 1, further comprising a processing unit that converts the measured magnetic field data into induced current vector values ​​and determines whether or not there is a defect in the battery cell or the location of the defect in the battery cell.

7. Each of the first measuring member, the second measuring member, and the third measuring member is bar-shaped or rod-shaped. The battery cell defect detection device according to claim 1, wherein the magnetic field measuring unit scans the battery cell by moving in the longitudinal direction of the battery cell.

8. The battery cell defect detection device according to claim 1, wherein each of the first measuring member, the second measuring member, and the third measuring member individually generates magnetic field data.

9. The battery cell defect detection device according to claim 8, wherein a three-dimensional magnetic field vector value is generated from magnetic field data individually generated from each of the first measuring member, the second measuring member, and the third measuring member.

10. The battery cell defect detection device according to claim 6, wherein the magnetic field data is a magnetic field image (MFI).

11. The battery cell defect detection device according to claim 1, wherein the types of defects to be detected include at least one of the following: a bent portion of the electrode plate of the battery cell, a broken portion of the electrode plate, a portion of the coating of the electrode plate in which the electrode active material is unevenly applied, a broken portion of the electrode lead or electrode tab of the battery cell, and a portion of the stacked electrode plates being misaligned.

12. A step of receiving magnetic field data generated by the current flowing through the battery cell, measured by the magnetic field measurement unit; A step of deriving three-dimensional magnetic field vector values ​​for each of the multiple sub-regions of the battery cell from the received magnetic field data; A step of converting the derived magnetic field vector value into a three-dimensional induced current vector value; A step of comparing the induced current vector value with a predetermined current vector threshold to determine whether the induced current value falls within the normal range; and A battery cell defect detection method, comprising the step of using the result of a step of determining whether the induced current value falls within the normal range of current values ​​to detect whether the battery cell has a defect or the location of the defect in the battery cell.

13. The battery cell defect detection method according to claim 12, wherein the step of converting the derived magnetic field vector value into an induced current vector value includes the step of multiplying the induced current vector value by a correction coefficient.

14. The battery cell defect detection method according to claim 12, wherein the step of determining whether the induced current value falls within the normal range of current values ​​includes the step of determining that there is a current abnormality in the battery cell if the induced current vector value is greater than a predetermined upper limit current vector threshold or the induced current vector value is less than a predetermined lower limit current vector threshold.

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