KR20220095318A - Eddy current sensor for detecting crack of pouch type battery cell and method for detecting crack of battery cell using the same - Google Patents

Abstract

The present invention relates to an eddy current sensor for inspecting cracks in a pouch-type battery cell and a method for inspecting cracks in a battery cell using the same that can easily detect the presence and location of cracks on electrodes, electrode tabs, or welds. According to the present invention, an eddy current sensor for inspecting cracks in a battery cell comprises: a probe; a transmission unit disposed in the probe and having a structure in which a transmission coil for inducing eddy currents in a battery cell to be evaluated is wound; and a reception unit having a structure in which a reception coil disposed in the probe and disposed in a region spaced apart from the transmission unit to generate inductor power by an eddy current induced in the battery cell by the transmission coil is wound.

Description

Eddy current sensor for crack inspection of pouch-type battery cell and crack inspection method of battery cell using same

The present invention relates to an eddy current sensor for inspecting cracks in pouch-type battery cells and a method for inspecting cracks in battery cells using the same.

As the price of energy sources increases due to the depletion of fossil fuels and interest in environmental pollution is increased, the demand for eco-friendly alternative energy sources is becoming an indispensable factor for future life, and in particular, technology development for mobile devices. As energy consumption and demand increase, the demand for secondary batteries as an energy source is rapidly increasing.

Typically, in terms of battery shape, there is a high demand for prismatic secondary batteries and pouch-type secondary batteries that can be applied to products such as mobile phones with thin thickness, and lithium ion batteries with high energy density, discharge voltage, and output stability in terms of materials. Demand for lithium secondary batteries such as ion polymer batteries is high.

Secondary batteries are classified according to the structure of the positive electrode, the negative electrode, and the electrode assembly having a separator structure interposed between the positive electrode and the negative electrode. Typically, long sheet-type positive and negative electrodes are wound with a separator interposed between them A jelly-roll (winding type) electrode assembly of one structure, a stacked (stacked) 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, positive and negative electrodes of a predetermined unit A stack-folding type electrode assembly having a structure in which unit cells such as bi-cells or full cells are stacked in a state where they are stacked with a separator interposed therebetween may be mentioned.

In addition, the secondary battery is manufactured by injecting an electrolyte, which is a liquid electrolyte, in a state in which the electrode assembly is accommodated in the battery container, and sealing the battery container.

During the manufacturing process of the electrode or the assembly process of the electrode assembly, cracks may occur on the electrode, tab, and welding part due to the difference in elongation of the holding part and the uncoated part, physical external force caused by welding, etc. causes

However, when a crack occurs inside a battery cell, it is difficult to select a defect through a vision inspection, and when sealing is completed, it is difficult to non-destructively detect a crack inside a sealed battery cell.

Accordingly, there is a need to develop a technology for an apparatus and method capable of non-destructively detecting defects such as cracks inside a battery cell.

Korean Patent Registration No. 10-2023739

In order to solve the problems of the prior art as described above, the present invention provides an eddy current sensor for crack inspection of a pouch-type battery cell capable of non-destructively detecting cracks in a pouch-type battery cell, and a crack inspection method of a battery cell using the same. would like to provide

The present invention is to solve the above problems, and provides an eddy current sensor for inspecting cracks inside a battery cell. In one example, the eddy current sensor of the battery cell according to the present invention includes a probe; a transmitter disposed on the probe and having a structure in which a transmitter coil for inducing an eddy current in a battery cell to be evaluated is wound; and a receiver disposed in the probe, disposed in a region spaced apart from the transmitter, and having a structure in which a receiving coil is wound to generate induced electromotive force by an eddy current induced in a battery cell by the transmitting coil. At this time, the interval between the transmitter and the receiver is in the range of 2 to 15 mm, and the ratio (S1/R1) of the width (S1) of the transmitter on which the transmitter coil is wound and the width (R1) of the receiver on which the receiver coil is wound is 1.5 to It is characterized in that it is in the range of 10.

In a specific example, the ratio (S1/R1) of the width S1 of the transmitter to the width R1 of the receiver is in the range of 1.5 to 5.

In addition, the width S1 of the transmitter may be in the range of 20 to 150 mm, and the width R2 of the receiver may be in the range of 5 to 100 mm.

In another example, the number of turns of the transmitting coil wound on the transmitting unit is in the range of 30 to 200 turns, and the number of turns of the receiving coil wound around the receiving unit is in the range of 60 to 400 turns.

In another example, the diameter D1 of the transmitting coil is in the range of 0.01 to 2.0 mm, and the diameter D2 of the receiving coil is in the range of 0.01 to 1.0 mm.

Furthermore, the present invention provides a method for inspecting cracks inside a battery cell using an eddy current sensor. In one example, the method comprising: inducing an eddy current in a battery cell to be evaluated using an eddy current sensor and then detecting a signal change due to the induced eddy current; and determining whether a battery cell to be evaluated is cracked based on the distribution of amplitude and phase difference of the detected signal.

In this case, the battery cell to be evaluated may be a pouch-type battery cell.

In a specific example, detecting the signal change may include disposing the eddy current sensor on the shoulder line region of the pouch-type battery cell in a non-contact manner.

According to the eddy current sensor for crack inspection of a battery cell of the present invention and a crack inspection method of a battery cell using the same, the presence and location of cracks occurring on electrodes, electrode tabs, or welds can be easily detected.

In particular, in the eddy current sensor, the transmitter and the receiver are spaced apart, and the ratio (S1/R1) of the width (S1) of the transmitter on which the transmitter coil is wound and the width (R1) of the receiver on which the receiver coil is wound (S1/R1) is in the range of 1.5 to 10 In this case, the difference between the normal signal and the bad signal can be greatly increased to increase the accuracy of the inspection.

1 is a schematic diagram illustrating a crack detection principle using an eddy current.
2 is a schematic diagram of an eddy current sensor according to an embodiment of the present invention.
3 is a view showing an embodiment of inspecting a battery cell for cracks using an eddy current sensor according to another embodiment of the present invention.
4 is a graph showing a result of checking whether a battery cell is cracked using an eddy current sensor according to an embodiment of the present invention.
5 is a graph showing a result of checking whether a battery cell is cracked using an eddy current sensor according to a comparative form.
6 is a schematic diagram of an eddy current sensor according to another embodiment of the present invention.
7 is a graph showing a result of checking whether a battery cell is cracked using an eddy current sensor according to another embodiment of the present invention.

Since the present invention can have various changes and can have various forms, specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to the specific disclosed form, it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

In the present application, terms such as "comprise" or "have" are intended to designate that a feature, number, step, operation, component, part, or a combination thereof described in the specification exists, but one or more other features It is to be understood that it does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof. Also, when a part of a layer, film, region, plate, etc. is said to be “on” another part, it includes not only the case where the other part is “directly on” but also the case where there is another part in between. Conversely, when a part of a layer, film, region, plate, etc. is said to be “under” another part, it includes not only cases where it is “directly under” another part, but also cases where another part is in between. In addition, in the present application, “on” may include the case of being disposed not only on the upper part but also on the lower part.

The present invention provides an eddy current sensor for crack inspection of a pouch-type battery cell and a crack inspection method of a battery cell using the same.

In general, a secondary battery is manufactured by injecting an electrolyte, which is a liquid electrolyte, in a state in which the electrode assembly is accommodated in the battery container, and sealing the battery container. During the manufacturing process of the electrode or the assembly process of the electrode assembly, cracks may occur on the electrode, tab, and welding part due to the difference in elongation of the holding part and the uncoated part, physical external force caused by welding, etc. causes However, when a crack occurs inside a battery cell, it is difficult to select a defect through a vision inspection, and when sealing is completed, it is difficult to non-destructively detect a crack inside a sealed battery cell.

Accordingly, the present invention provides an eddy current sensor for inspecting cracks in a battery cell capable of non-destructively detecting cracks in a battery cell, and a method for inspecting cracks in a battery cell using the same. In particular, in the eddy current sensor, the transmitter and the receiver are spaced apart, and the ratio (S1/R1) of the width (S1) of the transmitter on which the transmitter coil is wound and the width (R1) of the receiver on which the receiver coil is wound (S1/R1) is in the range of 1.5 to 10 In this case, the difference between the normal signal and the bad signal can be greatly increased to increase the accuracy of the inspection.

Hereinafter, an eddy current sensor for crack inspection of a pouch-type battery cell and a crack inspection method of a battery cell using the same will be described in detail.

The present invention uses the crack detection principle using eddy currents. 1 is a schematic diagram illustrating a crack detection principle using an eddy current.

Referring to FIG. 1 , when an alternating current flows through the coil, a primary magnetic field is generated around the coil. When the transmitting coil forming the primary magnetic field is brought to a conductor, an induced electromotive force is generated in the conductor by electromagnetic induction phenomenon, and this induced electromotive force is Lenz's law As a result, a current that interferes with the primary magnetic field flows, and this current is called an eddy current. A secondary magnetic field that interferes with the primary magnetic field is generated by the eddy current. At this time, the eddy current changes according to a change in the state, position, defect, material, etc. of the conductor, which causes a change in the secondary magnetic field, and the change in the secondary magnetic field causes a change in the primary magnetic field. This in turn causes a change in the impedance of the coil, and the voltage and phase of the circuit of the test device for measuring it also change. Accordingly, the change in the circuit value is amplified and the signal shape is output in a readable form.

That is, the eddy current sensor according to the present invention induces an eddy current on the surface to be inspected by adding an alternating current to the transmitting coil, and the receiving coil generates an induced electromotive force by the eddy current induced in the battery cell by the transmitting coil. On the other hand, the voltage (V) for the induced electromotive force and the alternating current (I) added to the transmitting coil are transmitted to the data processing device connected to the eddy current sensor according to the present invention to calculate the impedance value (Z = V / I). can In addition, it is possible to determine whether there is a crack inside the battery cell through the analysis of the impedance value.

In the present invention, the crack inside the battery cell means a crack generated on the electrode, the electrode tab, and the welding part. In a specific example, the cracking of the electrode means that an electrode manufactured through an electrode process such as drying and rolling after an electrode mixture including an electrode active material, a binder, and a conductive material is applied on a current collector during the electrode process , means a crack on the current collector caused by a difference in elongation between the current collector and the electrode mixture. In addition, the crack of the electrode tab may be a crack generated due to vibration or external force during welding due to the accumulation of stress in the wrinkles of the electrode swell and boundary part caused by the difference in elongation between the holding part and the uncoated part. Furthermore, the cracks on the welds may be unwelded parts caused by insufficient welding during welding, or cracks occurring during the welding process.

Cracks generated on the above-listed electrodes, electrode tabs, and welds can be observed from the outside of the battery cell because the inside of the battery cell is covered by the battery case when the electrode assembly is sealed with a battery case such as a laminate sheet. They are impossible cracks. However, if the eddy current sensor for crack inspection inside the battery cell of the present invention is used, there is an effect of detecting the cracks. Meanwhile, by measuring the impedance value of the battery cell with the eddy current sensor according to the present invention, and inputting the impedance value measured by the eddy current sensor into the discrimination function, it is possible to quickly and accurately inspect the state of the battery metal part.

In one example, the eddy current sensor according to the present invention includes a probe; a transmitter disposed on the probe and having a structure in which a transmitter coil for inducing an eddy current in a battery cell to be evaluated is wound; and a receiver disposed in the probe, disposed in a region spaced apart from the transmitter, and having a structure in which a receiving coil is wound to generate induced electromotive power by an eddy current induced in a battery cell by the transmitting coil. The transmitting coil and the receiving coil may be disposed in a non-contact state while being spaced apart from each other by a predetermined distance on the metal part of the battery cell to be measured. The transmitting coil and the receiving coil may be provided in a cylindrical shape, a rectangular pole, a polygonal pole, etc., and may be wound around the probe so that a magnetic field is formed in the longitudinal direction of the transmitting coil and the receiving coil.

In a specific example, the distance between the transmitter and the receiver is in the range of 2 to 15 mm. More specifically, the distance between the transmitter and the receiver may be in the range of 2 to 15 mm, in the range of 5 to 14 mm, in the range of 8 to 12 mm, or an average of 10 mm. On the other hand, when the distance between the transmitter and the receiver is less than 2 mm, the magnetic field generated in the transmitting coil and the magnetic field received in the receiving coil may interfere with each other, so it is preferable that the transmitter and the receiver are spaced apart from each other in the above-described range. In addition, if the distance between the transmitter and the receiver exceeds 15 mm, the magnetic field of the transmitter may not reach the object to be evaluated because the distance between the transmitter and the object to be evaluated is too great, and it is difficult to receive a signal generated from the object to be evaluated. can Therefore, the interval between the transmitter and the receiver is preferably within the above-described range.

In addition, in the eddy current sensor according to the present invention, the ratio (S1/R1) of the width S1 of the transmitter on which the transmitter coil is wound and the width R1 of the receiver on which the receiver coil is wound (S1/R1) may be in the range of 1.5 to 10. Specifically, the ratio (S1/R1) of the width (S1) of the transmitter on which the transmitter coil is wound and the width (R1) of the receiver on which the receiver coil is wound (S1/R1) is in the range of 1.5 to 8, in the range of 1.5 to 6, in the range of 1.5 to 5, It may be in the range of 1.7 to 4 and 1.9 to 3, for example, the width ratio (S1/R1) may be 2. If the width (S1) of the transmitter is less than 1.5 times the width (R1) of the receiver, the widths of the transmitter and receiver are similar to each other, so that the area of the primary magnetic field generated in the transmitter coil and the secondary generated in the receiver coil are similar. The areas of the magnetic fields may be similar to each other. Accordingly, it may not be easy to distinguish between a normal signal and a bad signal. That is, it may be difficult to detect cracks inside the battery cell. In addition, when the width (S2) of the transmitter exceeds 10 times the width (R2) of the receiver, the width (R2) of the receiver compared to the width (S2) of the transmitter is too small, so the eddy current induced in the battery cell to be evaluated It may be difficult to detect a signal change by

In a specific example, the width S1 of the transmitter is in the range of 20 to 150 mm, and the width R1 of the receiver is in the range of 5 to 100 mm. More specifically, the width S1 of the transmitter on which the transmitter coil is wound may be in the range of 20 to 150 mm, in the range of 35 to 130 mm, in the range of 50 to 110 mm, in the range of 65 to 100 mm, in the range of 75 to 95 mm, or in the range of 80 mm. have. In addition, the width R1 of the receiver on which the receiving coil is wound may be in the range of 5 to 100 mm, in the range of 10 to 80 mm, in the range of 15 to 60 mm, in the range of 20 to 50 mm, in the range of 30 to 45 mm, or in the range of 40 mm. For example, the eddy current sensor according to the present invention has a structure in which the width S1 of the transmitter is 80 mm and the width R1 of the receiver is 40 mm.

On the other hand, in the eddy current sensor according to the present invention, the width S1 of the transmitter corresponds to the length L of the evaluation region of the battery cell to be evaluated, or has a length of 0.9 to 1.2 times the length L . Here, the evaluation area of the battery cell means a terrace area of the pouch-type battery cell. Specifically, the evaluation region of the battery cell is a terrace region of the battery cell, and refers to a length in a direction perpendicular to a direction in which the electrode leads protrude. For example, the length of the battery cell L: the transmitter S1: the receiver R1 may have a ratio of 2.25:2:1.

In another example, in the eddy current sensor according to the present invention, the transmitting unit and the receiving unit have a structure in which winding grooves are formed in regions in which the transmitting coil and the receiving coil are wound, respectively. Specifically, the winding groove may have a structure formed along the outer peripheral surfaces of the transmitter and receiver of the probe. By the winding groove, the transmitting coil and the receiving coil may be wound around the probe more stably.

In addition, in the eddy current sensor according to the present invention, the ratio (N1/N2) of the number of turns (N1) of the receiving coil wound on the receiving unit to the number of turns (N2) of the transmitting coil wound on the transmitting unit (N1/N2) can have a range of 2 to 5 have. Alternatively, the ratio (N1/N2) may be in the range of 3 to 4, in the range of 3.5 to 3.8, or about 3.75.

In a specific example, the number of turns (N2) of the transmitting coil wound on the transmitter may be in the range of 30 to 200 turns, and the number of turns (N1) of the receiving coil wound around the receiver may be in the range of 60 to 400 turns. The number of turns N2 of the transmitting coil wound around the transmitting unit may be in the range of 30 to 180 turns, in the range of 40 to 160, in the range of 50 to 140, in the range of 60 to 120 turns, in the range of 70 to 100 turns, or about 80 turns. . In addition, the number of turns (N2) of the receiving coil wound on the receiving unit may be in the range of 60 to 400 turns, in the range of 120 to 380 turns, in the range of 180 to 360 turns, in the range of 240 to 340 turns, in the range of 280 to 320 turns, or about 300 turns. have. For example, the number of turns of the transmitting coil wound on the transmitter may be 80, and the number of turns of the receiving coil wound on the receiver may be 300.

In the eddy current sensor according to the present invention, since the transmitting coil and the receiving coil are wound in the transmitting unit and the receiving unit, respectively, as described above, it is possible to increase the accuracy of the crack inspection of the battery cell to be evaluated. Specifically, since the receiving coil is wound more than the transmitting coil, it is possible to effectively receive the eddy current signal generated in the battery cell.

In another example, at this time, the diameter of the transmitting coil and the receiving coil has a range of 0.01 to 2 mm. In a specific example, the ratio (D1/D2) of the diameter (D1) of the transmitting coil to the diameter (D2) of the receiving coil is in the range of 1.5 to 5.0.

In a specific example, the diameter of the transmitting coil has a structure larger than the diameter of the receiving coil. This is to generate a stronger and more uniform magnetic field in the battery cell to be evaluated. In a specific example, the diameter of the transmitting coil is in the range of 0.05 to 1.5 mm, in the range of 0.08 to 1.3 mm, in the range of 0.1 to 1.0 mm, in the range of 0.12 to 0.8 mm, in the range of 0.15 to 0.5 mm, and in the range of 0.18 to 0.3 mm. For example, the diameter of the transmission coil may be about 0.2 mm. In addition, the diameter of the receiving coil is in the range of 0.01 to 1.5 mm, in the range of 0.02 to 1.0 mm, in the range of 0.03 to 0.5 mm, in the range of 0.04 to 0.2 mm, in the range of 0.05 to 0.1 mm, in the range of 0.06 to 0.08 mm. For example, the diameter of the receiving coil may be about 0.07 mm.

Furthermore, the eddy current sensor according to the present invention can adjust the distance between the transmitter and the receiver. In a specific example, the receiver may be installed at the lower end of the transmitter to be slidable up and down. The transmitter may have a structure in which a groove is formed along the length of the probe from one end. In addition, the receiving unit may be partially or entirely inserted into the groove formed in the transmitting unit. In this case, the perimeter of the receiver is formed to correspond to the inner perimeter of the groove formed in the transmitter. However, it is preferable that the groove of the transmitter has a structure formed larger than the circumference of the receiver. That is, the receiver has a structure that is slidably installed in the groove of the transmitter. Accordingly, the eddy current sensor according to the present invention can easily adjust the distance between the transmitter and the receiver.

In addition, the present invention provides a method for inspecting cracks in a battery cell using the above-described eddy current sensor.

In one example, the method for inspecting cracks in a battery cell according to the present invention includes the steps of inducing an eddy current in a battery cell to be evaluated using an eddy current sensor, and then detecting a signal change due to the induced eddy current; and determining whether a battery cell to be evaluated is cracked based on the distribution of amplitude and phase difference of the detected signal.

Furthermore, in the determining whether the battery cell is cracked, when the measurement signal of the battery cell to be evaluated is out of the range of the reference signal based on the reference signal of the normal battery cell, it may be determined as defective.

Meanwhile, the battery cell to be evaluated may be a pouch-type unit cell. In a specific example, the pouch-type battery cell has a structure in which an electrode assembly having a cathode/separator/cathode structure is embedded in a laminate sheet casing in a state in which it is connected to electrode leads formed outside of the casing. In this case, the electrode leads may be drawn out of the sheet and extend in the same direction or opposite directions.

Furthermore, the step of detecting the signal change further includes the process of non-contact disposing of the eddy current sensor in the shoulder line region of the pouch-type battery cell.

The width S1 of the transmitter may correspond to the length L of the evaluation region of the battery cell to be evaluated, or may be 0.9 to 1.2 times as long as the length L. Here, the evaluation area of the battery cell means a terrace area of the pouch-type battery cell. Specifically, the evaluation region of the battery cell is a terrace region of the battery cell, and refers to a length in a direction perpendicular to a direction in which the electrode leads protrude. For example, the length of the battery cell L: the transmitter S1: the receiver R1 may have a ratio of 2.25:2:1.

The method for inspecting cracks in a battery cell according to the present invention can easily detect the presence and location of cracks occurring on electrodes, electrode tabs, or welds. In particular, the method for inspecting cracks in a battery cell using an eddy current according to the present invention has an effect of increasing the accuracy of inspecting cracks in a battery cell by using two eddy current sensors arranged side by side.

Hereinafter, various types of the eddy current sensor for crack inspection inside a battery cell according to the present invention will be described in detail.

(First embodiment)

2 is a schematic diagram of an eddy current sensor according to an embodiment of the present invention. Referring to FIG. 2 , the eddy current sensor 100 according to the present invention includes a probe 110 ; a transmitter 120 disposed in the probe 110 and having a structure in which a transmitting coil 121 for inducing an eddy current in a battery cell to be evaluated is wound; and a receiving coil 131 disposed in the probe 110, disposed in a region spaced apart from the transmitting unit 120, and generating induced electromotive power by an eddy current induced in a battery cell by the transmitting coil 121 is wound It is configured to include a receiving unit 130 of the structure.

Specifically, when an alternating current is applied to the transmitting coil 121 , a primary magnetic field is formed around the transmitting coil 121 . In the drawings, the coil is in the shape of a spring, but is not limited thereto. When the coil in which the primary magnetic field is formed is brought to a battery cell, which is an object to be inspected, an eddy current that interferes with the primary magnetic field flows by generating an induced electromotive force in the battery cell due to electromagnetic induction. In this way, the transmitting coil 121 induces an eddy current in the battery cell to be evaluated.

In addition, the receiving coil 131 is located below the transmitting coil 121 , but is located closer to the battery cell, which is an object to be inspected, compared to the transmitting coil 121 . The receiving coil 131 serves to generate induced electromotive force by the eddy current induced in the battery cell by the transmitting coil 121 .

In the receiving coil 131 , the eddy current induced by the transmitting coil 121 is formed due to factors such as the state, location, defect, and material of the battery cell as the object to be inspected. generate induced electromotive force. On the other hand, the voltage (V) for the induced electromotive force and the alternating current (I) added to the transmitting coil are transmitted to the data processing device connected to the eddy current sensor according to the present invention to calculate the impedance value (Z = V / I). can In addition, it is possible to determine whether there is a crack inside the battery cell through the analysis of the impedance value.

On the other hand, the eddy current sensor 100 according to the present invention has a structure in which the transmitter 120 and the receiver 130 are spaced apart from each other at intervals of 2 to 15 mm. The transmitter 120 and the receiver 130 may be disposed on the same plane, but in this case, the magnetic field generated by the transmitting coil 121 and the magnetic field received by the receiving coil 131 may interfere with each other. . In addition, when the distance between the transmitter 120 and the receiver 130 exceeds 15 mm, the distance between the transmitter 120 and the battery cell to be evaluated increases, so that an eddy current is applied to the entire metal part to be evaluated in the battery cell. may not be induced. Therefore, it is preferable that the transmitter 120 and the receiver 130 be spaced apart from each other within the above-described range. For example, the transmitter 120 and the receiver 130 have a structure spaced apart from each other by an interval of about 10 mm.

In addition, in the eddy current sensor 100 according to the present invention, the ratio (S1/R1) of the width S1 of the transmitter to the width R1 of the receiver is in the range of 1.5 to 10. For example, the ratio (S1/R1) of the width S1 of the transmitter to the width R1 of the receiver is two.

Specifically, the eddy current sensor 100 according to the present invention has a structure in which the width S1 of the transmitter is in the range of 20 to 150 mm, and the width R1 of the receiver is in the range of 5 to 100 mm. For example, in the eddy current sensor 100 according to the present invention, the width S1 of the transmitter 120 is 80 mm, and the width R1 of the receiver 130 is 40 mm. In the eddy current sensor 100 according to the present invention, since the width S1 of the transmitter 120 and the width R1 of the receiver 130 have the above ratio and length, the difference between the normal signal and the bad signal is greatly increased and inspected It has the effect of improving the accuracy of

Example 1

The crack test inside the battery cell was performed using the eddy current sensor of 1st Embodiment. For reference, in the eddy current sensor of the first embodiment, the distance between the transmitter and the receiver was 10 mm, the width S1 of the transmitter was 80 mm, and the width R1 of the receiver was 40 mm.

In addition, two pouch-type battery cells having a front (terrace area) length of 90 mm of the battery cell were prepared. In one of these battery cells, a notch defect having a size of 10 mm was formed in the electrode tab portion.

3 is a view showing an embodiment of inspecting a battery cell for cracks using an eddy current sensor according to another embodiment of the present invention. The crack test inside the battery cell 1 was performed using the eddy current sensor 100 . Specifically, after the eddy current sensor 100 was spaced apart from the battery cell 1 to be measured at an interval of about 1.5 mm, AC power was applied to the eddy current sensor to test for cracks inside the battery cell.

And, the result is shown in FIG. In FIG. 4 , the x-axis represents the normal battery cell and the abnormal battery cell, and the y-axis represents the resistance value of the eddy current sensor. It can be seen that the resistance values of the normal battery cell and the abnormal battery cell in which the crack occurred are significantly different. That is, it can be confirmed that the eddy current sensor for inspecting cracks inside a battery cell according to the present invention has excellent inspection accuracy when inspecting cracks inside a battery cell.

Comparative Examples 1-4

Four types of eddy current sensors were prepared to inspect the cracks inside the battery cell. The specific form of the eddy current sensor is shown in Table 1 below.

Distance between transmitter and receiver (mm) Width of transmitter (mm) Width of receiver (mm) note Comparative Example 1 0 80 40 insert type Comparative Example 2 20 80 40 Comparative Example 3 10 60 60 Comparative Example 4 10 100 10

A crack test inside the battery cell was performed in the same manner as in Example 1. And, the result is shown in FIG. 5A to 5D are graphs of results of internal crack inspection of a battery cell using Comparative Examples 1 to 4, respectively.

Referring to FIG. 5 , it can be seen that the resistance values of the normal battery cells and the defective battery cells in which cracks occur are almost the same. That is, in the eddy current sensor of the comparative example, it is difficult to distinguish between a normal battery cell and an abnormal battery cell when inspecting cracks inside the battery cell, and it is determined that the accuracy of the crack inspection is low.

(Second embodiment)

6 is a schematic diagram of an eddy current sensor according to another embodiment of the present invention. Referring to FIG. 6 , in the eddy current sensor 200 according to the present invention, the number of turns N1 of the transmitting coil 221 wound around the transmitting unit 220 is the number of turns N1 of the receiving coil 231 wound around the receiving unit 230 . The ratio of players N2 (N2/N1) ranges from 2 to 5. Specifically, the number of turns N1 of the transmitting coil 221 wound around the transmitting unit 220 is in the range of 30 to 200 turns, and the number of windings N1 of the receiving coil 231 wound around the receiving unit 230 is 60 to 200. 400 times range. For example, the number of turns of the transmitting coil 221 wound around the transmitting unit 220 is 80, and the number of windings of the receiving coil 221 wound around the receiving unit 220 is 300.

In the eddy current sensor 200 according to the present invention, the transmitting coil 221 and the receiving coil 231 are wound around the transmitting unit 220 and the receiving unit 230, respectively, as described above. accuracy can be improved. Specifically, since the receiving coil 231 is wound more than the transmitting coil 221 , there is an effect that an eddy current signal generated in the battery cell can be effectively received.

The description of each configuration has been described above, and a detailed description of each configuration will be omitted.

Example 2

The crack test inside the battery cell was performed using the eddy current sensor of 2nd Embodiment. For reference, in the eddy current sensor of the second embodiment, the distance between the transmitter and the receiver was 10 mm, the width S1 of the transmitter was 80 mm, and the width R1 of the receiver was 40 mm.

In addition, the number of turns of the transmitting coil wound on the transmitter was 80, and the number of turns of the receiving coil wound on the receiver was 300. Furthermore, the diameters of the transmitting coil and the receiving coil were 0.2 mm and 0.07 mm, respectively.

And, the crack test inside the battery cell was performed in the same manner as in Example 1. And, the result is shown in FIG.

Referring to FIG. 7 , it can be seen that the resistance values of the normal battery cells and the abnormal battery cells in which cracks occur are significantly different. That is, it can be confirmed that the eddy current sensor for the crack inspection inside the battery cell according to the present invention has excellent inspection accuracy when inspecting the crack inside the battery cell.

Above, the present invention has been described in more detail through drawings and examples. However, the configuration described in the drawings or embodiments described in the present specification is only one embodiment of the present invention and does not represent all the technical spirit of the present invention, so at the time of the present application, various equivalents and It should be understood that there may be variations.

1: battery cell
100, 200: eddy current sensor
110, 210: probe
120, 220: transmitter
121, 221: transmitting coil
130, 230: receiver
131, 231: receiving coil

Claims (12)

probe;
a transmitter disposed on the probe and having a structure in which a transmitter coil for inducing an eddy current in a battery cell to be evaluated is wound; and
It is disposed on the probe, it is disposed in a region spaced apart from the transmitter, and includes a receiver having a structure in which a receiving coil is wound to generate induced electromotive power by an eddy current induced in a battery cell by the transmitting coil,
The distance between the transmitter and the receiver is in the range of 2 to 15 mm,
The ratio (S1/R1) of the width (S1) of the transmitting unit on which the transmitting coil is wound and the width (R1) of the receiving unit on which the receiving coil is wound (S1/R1) is in the range of 1.5 to 10. Eddy current for crack inspection inside the battery cell sensor.
The method of claim 1,
An eddy current sensor in which the ratio (S1/R1) of the width (S1) of the transmitter and the width (R1) of the receiver is in the range of 1.5 to 5.
The method of claim 1,
The width (S1) of the transmitter is in the range of 20 to 150 mm eddy current sensor.
The method of claim 1,
The width (R1) of the receiver is in the range of 5 to 100 mm eddy current sensor.
The method of claim 1,
An eddy current sensor in which the number of turns of the transmitting coil wound on the transmitting unit is in the range of 30 to 200 turns.
The method of claim 1,
An eddy current sensor in which the number of turns of the receiving coil wound on the receiving unit is in the range of 60 to 400 turns.
The method of claim 1,
An eddy current sensor in which the ratio (D1/D2) of the diameter (D1) of the transmitting coil wound around the transmitter and the diameter (D2) of the receiving coil wound around the receiving coil is in the range of 1.5 to 5.0.
8. The method of claim 7,
The diameter (D1) of the transmitting coil is in the range of 0.01 to 2.0 mm,
An eddy current sensor with a diameter (D2) of the receiving coil in the range of 0.01 to 1.0 mm.
A method for inspecting cracks inside a battery cell using the eddy current sensor according to claim 1 .
10. The method of claim 9,
Inducing an eddy current in a battery cell to be evaluated using an eddy current sensor, and then detecting a signal change due to the induced eddy current; and
and determining whether the battery cell to be evaluated is cracked based on the distribution of amplitude and phase difference of the detected signal.
11. The method of claim 10,
A battery cell to be evaluated is a method for inspecting cracks inside a battery cell, characterized in that it is a pouch-type battery cell.
12. The method of claim 11,
The step of detecting the signal change includes the process of non-contact disposing of an eddy current sensor on a shoulder line region of a pouch-type battery cell.

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