KR102263601B1 - Inner crack detection apparatus for battery - Google Patents

Abstract

The present invention provides a battery internal crack inspection device capable of accurately detecting cracks existing inside a sealed battery case. To this end, the battery internal crack inspection device includes a transmitter for transmitting a first signal toward an inspection area where internal cracks of the battery are expected; a receiver disposed to face the transmitter with the battery interposed therebetween and for receiving a modified second signal while the first signal passes through the inspection area; and a control unit for comparing the second signal with a preset reference judgment value to determine a crack state of the inspection area. The transmitter and the receiver are relatively moved with respect to the test area in the test progress direction. The transmitter includes a first horizontal portion disposed parallel to the direction of inspection, and a first signal transmission region having a first vertical portion shorter than the first horizontal portion.

Description

Battery internal crack inspection device {INNER CRACK DETECTION APPARATUS FOR BATTERY}

The present invention relates to a battery internal crack inspection device, and more particularly, to a battery internal crack inspection device capable of accurately detecting a crack in an electrode existing inside a sealed case.

Secondary batteries are in high demand for prismatic batteries and pouch-type batteries, which 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.

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 (winding type) electrode assembly in which a long sheet-shaped positive electrode and negative electrode are wound with a separator interposed therebetween. and a stack type (stacked type) electrode assembly in which a plurality of positive and negative electrodes cut in units of a predetermined size are sequentially stacked with a separator interposed therebetween.

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 such a stack-pouch-type battery has excellent occupancy space, efficient manufacturing cost, and low weight. And the amount of use is gradually increasing for reasons such as easy shape deformation.

Briefly describing the manufacturing process of such a stack-pouch type battery, first, a plurality of positive and negative electrodes cut into units of a predetermined size are sequentially stacked with a separator interposed therebetween to manufacture a stacked 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 lead is 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.

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 region to which the active material is applied and the electrode uncoated region to which the active material is not applied, and due to the physical external force caused by welding, the electrode tab region Cracks may occur in the electrode lead, and such cracks are intensively generated in the bending region of each electrode tab for connecting a plurality of electrode tabs stacked on one electrode lead. The cracks generated in this way cause low voltage failure.

In this situation, as described above, due to the characteristics of the manufacturing and assembling process of the stack-pouch type battery, the bending area of the electrode tabs, where cracks are expected, is inside the pouch type case. was difficult to accurately detect or judge from the outside.

Republic of Korea Patent Publication No. 2019-0107933 (published on September 23, 2019)

An object of the present invention for solving the above-described problems is to provide a battery internal crack inspection device capable of accurately detecting cracks in electrodes existing inside the sealed case after sealing is completed.

Battery internal crack inspection apparatus according to an embodiment of the present invention for solving the above-described problems, a transmitter for transmitting a first signal toward the inspection area where the internal crack of the battery is expected; a receiver disposed to face the transmitter with the battery interposed therebetween and configured to receive a modified second signal while the first signal passes through the inspection area; and a control unit for determining a crack state of the inspection region by comparing the second signal with a preset reference judgment value, wherein the transmitter and the receiver are relatively moved with respect to the inspection region along the inspection progress direction , The transmitter includes a first signal transmission region, wherein the first signal transmission region has a first horizontal portion disposed parallel to the inspection proceeding direction and a first vertical portion shorter than the first horizontal portion in the inspection proceeding direction is formed to extend elongately along, the receiving unit has a second signal receiving area, wherein the second signal receiving area is a second horizontal portion arranged parallel to the inspection proceeding direction and a second length longer than the second horizontal portion It has a portion and is formed to be elongated in a direction intersecting the inspection proceeding direction, and the first horizontal portion of the first signal transmission region and the second vertical portion of the second signal reception region are disposed to cross each other.

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In the battery internal crack inspection apparatus according to the embodiment of the present invention, the inspection region may be a bending region of electrode tabs connected to the electrode lead or a welding region of the electrode tab and the electrode lead.

In the battery internal crack inspection apparatus according to the embodiment of the present invention, the length of the first horizontal portion may exceed twice the length of the first vertical portion, preferably, the length of the first horizontal portion is 4.5 to 5.5 mm, and the length of the first vertical part may be 0.5 to 1.5 mm.

In the battery internal crack inspection apparatus according to an embodiment of the present invention, the transmitter is arranged to be spaced apart from one side of the battery at a first interval, and the receiver is spaced apart from the other side of the battery at a second interval to is disposed, and the first interval and the second interval may be independently adjusted.

In the battery internal crack inspection apparatus according to an embodiment of the present invention, the receiver preferably maintains the same height as the outer surface of the battery.

According to the present invention, by using a first signal transmission region having a first horizontal portion and a first vertical portion shorter than the first horizontal portion disposed parallel to the inspection progress direction, the method passes through the crack site existing in the bending area of the electrode tab. In the case of a pouch-type battery capable of increasing the transmission rate of the first signal and having an atypical external shape, even if the actual inspection progress direction deviates from the direction in which internal cracks are expected to exist, it is possible to determine the appropriateness of the first signal passing through the crack area. The transfer rate can be guaranteed, and accordingly, the state of internal cracks can be accurately detected and judged.

According to the present invention, a first signal transmission region having a first horizontal portion and a first vertical portion shorter than the first horizontal portion disposed parallel to the inspection proceeding direction, a second horizontal portion and a second horizontal portion disposed parallel to the inspection proceeding direction By arranging the second signal receiving areas having the second vertical portions longer than the two horizontal portions to cross each other, it is possible to prevent information loss of the second signal caused by non-uniform bending of each electrode tab and welding mismatch with the electrode leads. , it is possible to more accurately detect and determine the state of the internal crack by increasing the reception rate of the second signal received from the receiver.

1 is an exemplary view showing a battery internal crack inspection apparatus according to an embodiment of the present invention.
2 is a partial cross-sectional view illustrating a battery internal crack inspection apparatus according to an embodiment of the present invention.
3 is a partial plan view illustrating a battery internal crack inspection apparatus according to an embodiment of the present invention.
4 is an exemplary view showing a comparison of the operation by the linear first signal transmission region and the spot-type first signal transmission region according to an embodiment of the present invention.
5 is a partial cross-sectional view for explaining the operation of the receiver of the battery internal crack inspection apparatus according to an embodiment of the present invention.
6 is an exemplary view for explaining the control unit of the battery internal crack inspection apparatus according to an embodiment of the present invention.
7 is a partial cross-sectional view for explaining an operation example of the transmitter and the receiver of the battery crack inspection apparatus according to an embodiment of the present invention.

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.

1 is an exemplary view showing a battery internal crack inspection device according to an embodiment of the present invention, Figure 2 is a partial cross-sectional view showing a battery internal crack inspection device according to an embodiment of the present invention, Figure 3 is this It is a partial plan view showing a battery internal crack inspection apparatus according to an embodiment of the present invention.

The battery internal crack inspection apparatus according to an embodiment of the present invention accurately detects the crack state existing inside the case 14 in the manufacturing and assembling process of the stack-pouch type battery 10, and based on the detected crack state In this way, it is possible to accurately determine whether the battery 10 is defective.

Of course, the battery internal crack inspection apparatus according to an embodiment of the present invention is not limited to the stack-pouch type battery 10, and may be applied to all batteries having various structures and shapes. Hereinafter, for convenience of description, the stack type electrode assembly A stack-pouch-type battery 10 having (11) and a pouch-type case 14 will be described as an example.

1 to 3 , the battery internal crack inspection apparatus according to an embodiment of the present invention may include a transmitter 110 , a receiver 120 , and a controller 130 .

The transmitter 110 may be disposed on one side of the battery 10 as an inspection object.

The transmitter 110 may transmit the first signal S1 toward the inspection area CA where cracks are expected inside the battery 10 .

The first signal S1 may pass through the inspection area CA of the battery 10, and in the process of passing through the inspection area CA, the first 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.

That is, the first signal S1 may be transmitted to the receiver 120 as it is when there is no battery 10 between the transmitter 110 and the receiver 120, and the transmitter ( When the battery 10 is present between 110) and the receiver 120, the first signal S1 passes through the battery 10 and then is transformed into a second signal S2 different from the first signal S1, , the modified second signal S2 may be transmitted to the receiver 120 .

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 battery 10, an induced electromotive force is generated in the inspection area CA due to electromagnetic induction, thereby generating eddy currents that interfere with the primary magnetic field. will flow As a result, a transformed secondary magnetic field (corresponding to the second signal) is formed in the 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 battery 10 as an inspection object, and may be disposed to face the transmitter 110 with the battery 10 interposed therebetween.

The receiver 120 may receive the modified second signal S2 as the first signal S1 transmitted from the transmitter 110 passes through the inspection area CA of the 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 as an induced electromotive force is generated in the inspection area CA of the battery 10 by the primary magnetic field formed through the transmitter 110 , the battery 10 inspection area CA ), the receiver 120 disposed in the region opposite to the transmitter 110 may receive the second signal S2 corresponding to the transformed secondary magnetic field while the primary magnetic field is canceled by the eddy current.

In addition, the space between the transmitter 110 and the inspection area CA of the battery 10 may be a zone where only the effect of the primary magnetic field (corresponding to the first signal) exists, and in this zone, the magnetic field signal strength is strong Also, the inspection area CA of the 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 battery 10 and the receiver 120 may be a region where only the effect of the secondary magnetic field (corresponding to the second signal) exists, and in this region, the strength of the magnetic field signal is the primary It has a smaller strength than the magnetic field.

Accordingly, the receiver 120 is placed on the opposite side of the transmitter 110 with the battery 10 interposed therebetween and passes through the inspection area CA of the battery 10 and is inspected based on the strength of the offset secondary magnetic field. A crack existing inside the area CA can be detected.

On the other hand, the battery internal crack inspection apparatus according to the present embodiment may further include an inspection device transfer unit. The inspection device transport unit may transport the transmitter 110 and the receiver 120 , and may transport the transmitter 110 and the receiver 120 together in parallel to the inspection area CA of the battery 10 .

In addition, the battery internal crack inspection apparatus according to the present embodiment may further include a stage. The stage may fix and support the battery 10 . Of course, the stage may align the position of the battery 10 or transfer the battery 10 using a known stage transfer unit.

As a result, the battery internal crack inspection apparatus according to the present embodiment can move the transmitter 110 and the receiver 120 using the inspection device transfer unit with respect to the fixed battery 10, and the position-fixed transmitter ( The battery 10 may be moved using a stage with respect to 110 ) and the receiver 120 .

On the other hand, the inspection area CA of the 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 . ) of the welding area.

For example, during the manufacturing and assembling process of the stack-pouch type 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 due to welding , cracks may occur in the region of the electrode tab 12 , and such cracks may occur in the bending region of the electrode tab 12 or the electrode tab 12 in which a plurality of electrode tabs 12 are connected to one electrode lead 13 . It is intensively generated in the welding area of the electrode lead 13 . And 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.

Also, due to the sealed case 14, the cracks C existing in the bending area of the electrode tab 12 and the welding area between the electrode tab 12 and the electrode lead 13 cannot be identified from the outside. Therefore, the inspection area CA sets an area estimated to be a bending area of the electrode tab 12 or a welding area between the electrode tab 12 and the electrode lead 13, and is located in the thus estimated inspection area CA. Inspection is performed while relatively moving the transmitter 110 and the receiver 120 in parallel to the extension direction CL of the crack C expected for the test.

That is, the crack C existing in the inspection area CA is detected while the transmitter 110 and the receiver 120 are relatively moved along the inspection progress direction D1. The inspection progress direction D1 refers to a relative movement direction between the transmitter 110 and the receiver 120 and the inspection area CA of the battery 10 .

Here, the cracks C existing in the bending area of the electrode tab 12 and the welding area of the electrode tab 12 and the electrode lead 13 are covered by the case 14 and thus cannot be identified from the outside, as well as in the pouch. Due to the atypical characteristics of the mold case 14, the different bending characteristics for each stacked electrode tab 12, and the welding mismatch between the electrode tab 12 and the electrode lead 13, There is a difficult problem in setting the reference plane or the reference line, and in particular, for the above reasons, the crack C existing in the bending region of the electrode tab 12 may also extend in an unspecified direction. As a result, as shown in FIG. 3 , the extension direction CL of the actual crack C and the inspection progress direction D1 may deviate while forming the inclination angle α.

As such, if the extension direction CL of the actual crack C and the inspection progress direction D1 do not match while forming the inclination angle α, it is impossible to accurately detect the state of the crack C existing in the inspection area CA. cases may arise.

To this end, the transmitter 110 according to the present embodiment may be set to have a first signal transmission area SA1 that is formed to be elongated along the test proceeding direction D1.

That is, the transmitting unit 110 according to the present embodiment includes a first horizontal portion A1 disposed parallel to the inspection proceeding direction D1, and a first vertical portion B1 shorter than the first horizontal portion A1. The branch may include a first signal transmission area SA1.

3 and 4 (a), while relatively moving the transmitter 110 in the test proceeding direction D1 with respect to the test area CA of the battery 10 as described above, the first signal transmitting area SA1 ) by sending the first signal S1 to the inspection area CA, it is possible to increase the transmission rate of the first signal S1 reaching the crack C formed while having an unspecified position and direction in the inspection area CA, and thus the crack ( C) It is possible to accurately detect the crack (C) state by increasing the reception rate of the second signal (S2) passing through the site. In addition, in the case of a pouch-type battery having an atypical external shape, even if the actual inspection progress direction (D1) deviates from the expected extension direction (CL) of the crack (C), the first signal (S1) reaching the crack (C) site ) can be guaranteed.

On the other hand, as in FIG. 4 (b), if the first signal transmission area SA1" of the transmission unit has a spot shape, the transmission rate of the first spot signal reaching the crack C is extremely low. In this case, when the inspection progress direction D1 deviates from the expected extension direction CL of the crack C, the proper transmission rate of the first signal S1 reaching the crack C cannot be guaranteed. Accordingly, the reception rate of the second signal S2 passing through the crack C is lowered, resulting in the inability to accurately detect the crack C.

According to the present embodiment, when examining the crack C existing in the bending region of the electrode tab 12 of the stack-pouch type battery 10 , the length of the first horizontal portion A1 is equal to the length of the first vertical portion B1 . ) may be set to exceed twice the length of, preferably, the length of the first horizontal part (A1) may be set within the range of 4.5 to 5.5 mm, and the length of the first vertical part (B1) is 0.5 It can be set within the range of to 1.5 mm.

5 is a partial cross-sectional view for explaining the operation of the receiver of the battery internal crack inspection apparatus according to an embodiment of the present invention.

Referring to FIG. 5 , the receiver 120 according to the present embodiment may be set to have a second signal transmission area SA2 elongated in a direction intersecting the inspection progress direction D1 .

That is, the receiver 120 according to the present embodiment has a second horizontal portion A2 disposed parallel to the inspection progress direction D1 and a second vertical portion B2 longer than the second horizontal portion A2. A second signal receiving area SA2 may be provided. In this case, the second vertical portion B2 may be longer than the first vertical portion B1 .

In addition, the second vertical portion B2 of the second signal receiving area SA2 may be disposed to cross the first horizontal portion A1 of the first signal transmitting area SA1 .

5 (a), when transmitting the first signal S1 while relatively moving the transmitter 110 in the inspection progress direction D1 with respect to the bending area of the electrode tab 12, the electrode tab 12 The second signal S2 that is deformed while passing through the bending region of the electrode tab 12 passes through all the bending regions of the electrode tab 12 due to non-uniform bending of each electrode tab 12 and welding mismatch with the electrode lead 13. The second signal S2 may be displaced from the first signal S1 in a straight line. That is, a phenomenon may occur in which the second signal S2 spreads widely in a direction (left and right in the drawing) crossing the inspection proceeding direction D1. Accordingly, the reception rate of the second signal S2 received by the receiver 120 ″ may be greatly reduced.

On the other hand, as shown in FIG. 5 (b), the first horizontal portion A1 disposed parallel to the inspection progress direction D1 and the first vertical portion B1 shorter than the first horizontal portion A1 Receiving a second signal having a first signal transmission area SA1, a second horizontal portion A2 disposed parallel to the inspection proceeding direction D1, and a second vertical portion B2 longer than the second horizontal portion A2 By arranging the regions SA2 to cross each other, the second signal S2 passing through all the bending regions of the electrode tab 12 deviates from the first signal S1 on a straight line and intersects the inspection proceeding direction D1. Even if it spreads widely (left and right in the drawing), the reception rate of the second signal S2 through the receiver 120 can be greatly increased. Accordingly, it is possible to more accurately detect and determine a crack state existing in the bending region of the electrode tab 12 .

6 is an exemplary view for explaining the control unit of the battery crack inspection apparatus according to an embodiment of the present invention.

Referring additionally to FIG. 6 , the controller 130 controls the first signal S1 transmitted to the transmitter 110 to pass through the bending region of the electrode tab 12 , which is the inspection region CA, while canceling the second signal ( S2) and a preset reference judgment value SS may be compared to detect and determine a crack state existing in the inspection area CA.

First, the control unit 130 outputs the calculated signal CS based on the first signal S1 transmitted to the transmitting unit 110 and the second signal S2 canceled while passing through the inspection area CA. can For example, the control unit 130 may include a signal processing module for processing the eddy current signal, the signal processing module includes the first signal S1 transmitted to the transmitter 110 and the test area of the battery 10 . The calculated signal CS may be calculated based on the second signal S2 canceled while passing through, and the calculated calculated signal CS may be output to a terminal such as a monitor.

In addition, when the calculated signal CS exists within the allowable error value H from the reference determination value SS, the control unit 130 may determine that there is no crack or a normal state having minor cracks, and the calculated signal CS When is out of the allowable error value (H) from the reference judgment value (SS), it can be determined as a defective state in which a crack exists.

For example, as in FIG. 6 (a), the entire section of the calculation signal CS corresponding to the section of the inspection area CA exists within the allowable error value H with respect to the reference judgment value SS, and the calculated signal ( When CS) has a symmetrical structure with respect to the center line, it can be determined that there is no crack C in the inspection area CA or has insufficient cracks, and in this case, the internal crack state of the battery 10 is normal. can be judged.

In addition, as shown in FIG. 6 (b), some sections of the calculation signal CS corresponding to the section of the inspection area CA exist within the allowable error value H with respect to the reference judgment value SS, but the calculated signal ( When the remaining partial section of CS) is out of the tolerance value (H) with respect to the reference judgment value (SS), and the calculated signal (CS) forms an asymmetric structure based on the center line, cracks ( C) may be determined to be partially present, and in this case, the internal crack state of the battery 10 may be determined to be defective.

In addition, as shown in FIG. 6 ( c ), although the calculated signal CS has a symmetrical structure with respect to the center line, the entire section of the calculated signal CS corresponding to the section of the inspection area CA is the reference judgment value SS ), if it is out of the allowable error value (H), it can be determined that the crack (C) exists in whole or in part in the inspection area (CA), and in this case, the internal cracking state of the battery 10 is defective. can be judged.

7 is a partial cross-sectional view for explaining an operation example of the transmitter and the receiver of the battery internal crack inspection apparatus according to an embodiment of the present invention.

Referring to FIG. 7 , the transmitter 110 according to this embodiment may be disposed to be spaced apart from one side 14a of the case 14 by a first interval 110d, and the first interval 110d is It can be independently adjusted by the inspection device transfer unit.

In addition, the receiving unit 120 according to the present embodiment may be disposed to be spaced apart at a second interval 120d with respect to the other side 14b of the case 14, and the second interval 120d is provided by the inspection device transfer unit. can be adjusted independently.

In this way, depending on the type of the inspection area CA, the transmitter 110 and the receiver 120 may be positioned while appropriately adjusting the first interval 110d and the second interval 120d by the inspection device transfer unit. When the final position is set, the crack C existing in the inspection area CA is detected while moving along the inspection progress direction D1.

When setting such a position, the receiving unit 120 according to the present embodiment preferably maintains the same height as the other side surface 14a of the case 14 . That is, the receiver 120 may maintain a state in which the case 14 is in close contact with the other side surface 14a.

As described above, by minimizing the second interval 120d between the inspection area CA and the receiving unit 120, the electrode tab 12 due to non-uniform bending of each electrode tab 12 and welding mismatch with the electrode lead 13. Information loss of the second signal S2 that has passed through the bending region can be minimized, and a high sensitivity can be achieved by increasing the reception rate of the second signal S2.

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.

110: transmitter
120: receiver
130: control unit

Claims (7)

a transmitter for transmitting a first signal toward an inspection area where internal cracks of the battery are expected;
a receiver disposed to face the transmitter with the battery interposed therebetween and configured to receive a modified second signal while the first signal passes through the inspection area; and
Comprising a control unit for determining the crack state of the inspection area by comparing the second signal and a preset reference judgment value,
The transmitter and the receiver are relatively moved with respect to the test area along the test progress direction,
The transmitting unit has a first signal transmitting area,
The first signal transmission region has a first horizontal portion disposed parallel to the inspection proceeding direction and a first vertical portion shorter than the first horizontal portion and is formed to extend long in the inspection proceeding direction,
The receiving unit has a second signal receiving area,
The second signal receiving region has a second horizontal portion disposed parallel to the inspection proceeding direction and a second vertical portion longer than the second horizontal portion and is formed to extend in a direction crossing the inspection proceeding direction,
The battery internal crack inspection apparatus, characterized in that the first horizontal portion of the first signal transmission region and the second vertical portion of the second signal reception region are arranged to cross each other. delete According to claim 1,
The inspection area is a battery internal crack inspection apparatus, characterized in that the bending area of the electrode tabs connected to the electrode lead or the welding area between the electrode tab and the electrode lead. According to claim 1,
The length of the first horizontal portion is a battery internal crack inspection device, characterized in that more than twice the length of the first vertical portion. 5. The method of claim 4,
The length of the first horizontal part is 4.5 to 5.5 mm, and the length of the first vertical part is 0.5 to 1.5 mm. According to claim 1,
The transmitter is disposed spaced apart at a first interval with respect to one side of the battery,
The receiving unit is disposed to be spaced apart from the other side of the battery at a second interval,
The first interval and the second interval are battery internal crack inspection device, characterized in that independently controlled. According to claim 1,
The battery internal crack inspection device, characterized in that the receiver maintains the same height as the outer surface of the battery.

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