Battery cell defect inspection device and method, and system including same

Abstract

The battery cell defect inspection device and method, and a system including the same, according to the embodiments and experimental examples of the present invention can calculate the difference in resistance measured at the metal part of a battery cell before and after heating, and compare the difference with a preset reference value to determine whether a defect has occurred in the metal part of the battery cell.

Description

[Technical Field]

[0001] This application claims the benefit of the filing date of Korean Patent Application No. 10-2023-0077226, filed with the Korean Intellectual Property Office on June 16, 2023, and all of the contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a battery cell defect inspection device and method, and a system including the same, and more specifically to a battery cell defect inspection device and method for inspecting defects occurring in metal parts of battery cells, and a system including the same. [Background technology]

[0003] As fossil fuels become scarce and environmental pollution concerns soar, environmentally friendly alternative energy sources are becoming increasingly important. Among the various alternative energy sources, the demand for rechargeable lithium secondary batteries is rapidly increasing.

[0004] As a response to environmental regulations and high oil prices, lithium secondary batteries are being applied to various industrial fields, from mobile devices to automobiles, robots, energy storage devices, etc. However, as a result, lithium batteries are easily exposed to external shocks, vibrations, etc.

[0005] Therefore, defect inspection is essential for lithium batteries to maintain high performance and stability, and defect inspection of metal parts is essential because defects in the metal parts of the battery that are electrically connected to the outside can significantly reduce performance and safety.

[0006] Generally, inspection of metal parts for defects can include inspection for broken tabs and inspection for defective welds.

[0007] Conventional defect inspections of metal parts involve disassembling the completed battery cell and then conducting a vision inspection, or visually determining whether defects exist using CT scans for non-destructive testing.

[0008] However, visual inspection of metal parts for defects has the drawback of making it difficult to accurately judge quality due to the vague criteria, and CT scans for metal part defects require a long time for imaging and evaluation.

[0009] In recent years, a new inspection method has been developed that uses a probe pin to measure the resistance between welded surfaces to determine whether a battery cell is defective. However, this method has the disadvantage of a high rate of failures due to the welding surface being bent, making it difficult for the probe pin to make contact. Furthermore, in the case of defects such as weak welds and partial breaks in the tabs, the change in resistance is so small that the battery cell may be mistakenly detected as a normal battery cell. Summary of the Invention [Problem to be solved by the invention]

[0010] SUMMARY OF THE INVENTION In order to solve the above problems, an object of the present invention is to provide a method for inspecting battery cells for defects.

[0011] Another object of the present invention to solve the above problems is to provide a battery cell defect inspection device.

[0012] Another object of the present invention to solve the above problems is to provide a battery cell defect inspection system. [Means for solving the problem]

[0013] To achieve the above object, a method for inspecting a battery cell for defects according to one embodiment of the present invention includes a step of calculating a difference between resistance values ​​measured before and after heat induction of a metal part of a battery cell, and a step of comparing the difference with a predetermined reference value to inspect whether a defect has occurred in the metal part.

[0014] Here, the step of calculating the difference in the resistance values ​​may include the steps of obtaining a first resistance value of the metal part, inducing heat generation in the metal part according to heat generation conditions, obtaining a second resistance value of the metal part in which heat generation is induced, and comparing the first resistance value with the second resistance value to calculate the difference value.

[0015] In this case, the heat generation condition may include at least one condition value for maintaining a temperature change of the electrolyte in the battery cell below a preset reference value.

[0016] In addition, the step of inducing heat generation in the metal part according to the heat generation condition may include the step of inducing heat generation in the metal part by charging and discharging the battery cell according to the heat generation condition.

[0017] For example, the heat generation condition may include at least one of a magnitude of a charge / discharge current, a charge / discharge time, and an external temperature for charging / discharging the battery cell.

[0018] At this time, the heat generation condition can be changed according to attribute information of the battery cell.

[0019] On the other hand, the resistance value may be the real part of the impedance value measured at a predefined frequency.

[0020] In addition, the step of inspecting whether or not a defect has occurred in the metal part may include a step of determining that a defect has occurred in the metal part if the difference value is equal to or greater than the reference value, and a step of determining that the battery cell is normal if the difference value is less than the reference value.

[0021] To achieve the above object, according to another embodiment of the present invention, a battery cell defect inspection device includes a memory and a processor that executes at least one instruction stored in the memory, the at least one instruction including: an instruction to calculate a difference between resistance values ​​measured before and after heat generation induction of a metal part of a battery cell; and an instruction to compare the difference with a preset reference value to inspect for the presence or absence of defects in the metal part.

[0022] Here, the instruction to calculate the difference in the resistance values ​​may include an instruction to obtain a first resistance value of the metal part, an instruction to induce heat generation in the metal part according to a heat generation condition, an instruction to obtain a second resistance value of the metal part in which heat generation is induced, and an instruction to compare the first resistance value and the second resistance value to calculate the difference value.

[0023] In this case, the heat generation condition may include at least one condition value for maintaining a temperature change of the electrolyte in the battery cell below a preset reference value.

[0024] In addition, the command to induce heat generation of the metal part according to the heat generation condition may include a command to induce heat generation of the metal part by charging / discharging the battery cell according to the heat generation condition.

[0025] For example, the heat generation condition may include at least one of a magnitude of a charge / discharge current, a charge / discharge time, and an external temperature for charging / discharging the battery cell.

[0026] At this time, the heat generation condition can be changed according to attribute information of the battery cell.

[0027] On the other hand, the resistance value may be the real part of the impedance value measured at a predefined frequency.

[0028] In addition, the command to inspect whether or not a defect has occurred in the metal part may include a command to determine that a defect has occurred in the metal part if the difference value is equal to or greater than the reference value, and a command to determine that the battery cell is normal if the difference value is less than the reference value.

[0029] In order to achieve the above object, according to yet another embodiment of the present invention, a battery cell defect inspection system includes an impedance measurement device that measures the resistance value of a battery cell, a heating device that induces heat generation in a metal portion of the battery cell, and a battery cell defect inspection device that inspects whether or not defects have occurred in the metal portion of the battery cell, and the battery cell defect inspection device calculates a difference between the resistance values ​​measured by the impedance measurement device before and after heat induction in the metal portion, and compares the difference value with a preset reference value to inspect whether or not defects have occurred in the metal portion.

[0030] In this case, the battery cell defect inspection device can obtain a first resistance value of the metal part from the impedance measurement device before inducing heat generation in the metal part, transmit heat generation conditions to the heat generation device to induce heat generation in the metal part, obtain a second resistance value of the metal part in which heat generation is induced from the impedance measurement device, and compare the difference between the first resistance value and the second resistance value with the reference value to inspect whether or not a defect has occurred in the metal part.

[0031] Here, the heat generation condition may include at least one condition value for maintaining a temperature change of the electrolyte in the battery cell below a preset reference value.

[0032] Meanwhile, the heat generating device may include a charge / discharge device.

[0033] The resistance value may also be the real part of the impedance value measured at a predefined frequency. [Effects of the Invention]

[0034] The battery cell defect inspection device and method, and the system including the same, according to the embodiments and experimental examples of the present invention induce heat generation in the battery cell to be inspected and compare the impedance measurements before and after the heat generation. This increases the resistance change of the metal part inside the defective battery cell due to the heat generation, enabling highly reliable inspection of the presence or absence of defects. [Brief explanation of the drawings]

[0035] [Figure 1] 1 is a block diagram of a battery cell defect inspection system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram of a control unit in a defect inspection device according to an embodiment of the present invention. [Figure 3] FIG. 1 is a flow chart for explaining a method for inspecting a battery cell for defects using a defect inspection device according to an embodiment of the present invention. [Figure 4] FIG. 1 is a conceptual diagram of a defect inspection system for inspecting pouch-type battery cells according to an experimental example of the present invention. [Figure 5] 10 is an image showing the temperature of a defective battery cell measured during heat induction according to an experimental example of the present invention. [Figure 6] 10 is a graph showing impedance measurement results for each frequency of a normal battery cell before and after heating according to an experimental example of the present invention. [Figure 7] 10 is a graph showing the results of measuring impedance for each frequency of a defective battery cell before and after heat generation according to an experimental example of the present invention. [Figure 8] 10 is a table summarizing resistance values ​​of normal and defective battery cells before and after heat generation according to an experimental example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0036] Since the present invention can be modified in various ways and can have various embodiments, specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, it is understood that this is not intended to limit the present invention to the specific embodiments, but rather to include all modifications, equivalents, or alternatives within the spirit and technical scope of the present invention. Like reference numerals are used to refer to like elements throughout the drawings.

[0037] Terms such as "first," "second," "A," and "B" may be used to describe various components, but the components should not be limited by these terms. These terms are used only to distinguish one component from another. For example, a first component may be termed a "second component," and similarly, a second component may be termed a "first component," without departing from the scope of the present invention. The term "and / or" includes a combination of multiple associated listed items or any of multiple associated listed items.

[0038] When a component is referred to as being "coupled" or "connected" to another component, it is understood that the component may be directly coupled or connected to the other component, but that there may be other components in between. Conversely, when a component is referred to as being "directly coupled" or "directly connected" to another component, it is understood that there are no other components in between.

[0039] The terms used in this application are merely used to describe specific embodiments and are not intended to limit the present invention. The singular expressions include the plural expressions unless the context clearly indicates otherwise. It should be understood that in this application, the terms "comprise" or "have" are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and do not preclude the presence or additional possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0040] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which this invention pertains. Terms as defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning they have in the context of the relevant art, and should not be interpreted as having an ideal or overly formal meaning unless expressly defined in this application.

[0041] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0042] FIG. 1 is a block diagram of a battery cell defect inspection system according to an embodiment of the invention.

[0043] Referring to FIG. 1, a battery cell defect inspection system S according to an embodiment of the present invention can detect at least one defect occurring in a metal part inside a battery cell by inducing heat generation in the battery cell being inspected.

[0044] More specifically, the battery cell defect inspection system S may include an impedance measuring device (Electrochemical Impedance Spectroscopy (EIS)) 1000, a heat generating device 3000, and a battery cell defect inspection device 5000.

[0045] The impedance measuring device 1000 can measure the resistance value of the battery cell before and after heat generation.

[0046] To explain in more detail with reference to an embodiment, the impedance measuring device 1000 may be connected to the positive and negative electrodes of a battery cell to be tested.

[0047] For example, the battery cell may be placed on a fixing part including a plurality of measurement pins. More specifically, the battery cell may be placed on the fixing part with its positive and negative electrodes in contact with one end of each of the plurality of measurement pins. Thus, the impedance measuring device 1000 may be connected to the other ends of the plurality of measurement pins, one end of which contacts the positive and negative electrodes of the battery cell. Thus, the impedance measuring device 1000 may be electrically connected to the positive and negative electrodes of the battery cell. The fixing part may be provided in various shapes, such as a cylindrical shape, a pouch shape, or a stack shape, to improve fixing strength depending on the shape of the battery cell to be measured.

[0048] Then, the impedance measuring device 1000 may apply an AC voltage or an AC current to the battery cell before and after heating. The impedance measuring device 1000 may then measure changes in amplitude and phase of the AC voltage or AC current passing through the battery cell to calculate an impedance value for each frequency. For example, the AC voltage or AC current may be provided in the form of a sine wave.

[0049] The heat generating device 3000 may be a device that induces heat generation in a metal part within the battery cell. More specifically, the heat generating device 3000 may be electrically or physically connected to the battery cell and induce heat generation in the metal part according to a predefined heat generating condition. Here, the heat generating condition may be condition setting information for minimizing a temperature change of an electrolyte within the battery cell.

[0050] In other words, the battery cell defect inspection system according to the embodiment of the present invention can induce heat generation only in the metal parts of the battery cell in accordance with the heat generation conditions so as to minimize the temperature change of the electrolyte of the battery cell, thereby preventing the occurrence of side reactions due to the temperature change of the electrolyte when inspecting the battery cell for defects.

[0051] Meanwhile, the heat generation condition may vary depending on the attribute information of the battery cell. For example, the attribute information of the battery cell is a factor that determines the battery model, and may include the type, material of the metal part, number of tabs, etc.

[0052] According to an embodiment, the heating device 3000 may be provided as a charging / discharging device. For example, the charging / discharging device may be connected to one end of a plurality of measurement pins, one end of which contacts the positive and negative electrodes of the battery cell, respectively, as in the impedance measuring device 1000. In other words, the charging / discharging device may be electrically connected to the positive and negative electrodes of the battery cell, respectively. The charging / discharging device may then charge / discharge the battery cell according to a predetermined heating condition. As a result, metal parts within the battery cell may be heated. In this case, the heating condition may include at least one of condition information regarding the magnitude of a charging / discharging current, the time for the charging / discharging current, and the external temperature, which is used to minimize a temperature change of the electrolyte within the battery cell. Here, the magnitude of the charging / discharging current may vary depending on the number and size of tabs, which are metal parts within the battery cell.

[0053] The heat generating device 3000 is not limited to the disclosed charge / discharge device, but may be applied to various devices capable of inducing heat generation in the metal parts within the battery cell.

[0054] The defect inspection device 5000 can be linked to at least one of the impedance measurement device 1000 and the heat generation device 3000. Thus, the defect inspection device 5000 can obtain the first resistance value and the second resistance value measured before and after the heat generation of the battery cell from the impedance measurement device 1000.

[0055] According to an embodiment, the first resistance value may be the real part of an impedance value corresponding to a predefined frequency among the impedance values ​​of the impedance measuring device 1000 measured for the battery cell before heat generation.

[0056] The second resistance value may also be the real part of the impedance value corresponding to a predefined frequency among the impedance values ​​for each frequency measured by the impedance measuring device 1000 after the battery cell is heated.

[0057] Here, the predefined frequency may be defined as a specific frequency equal to or higher than a predefined reference frequency. For example, the first resistance value and the second resistance value may be the real part of the impedance value at 850 Hz, which is one of the frequencies in the high frequency range equal to or higher than 600 Hz, which is the reference frequency.

[0058] The defect inspection device 5000 then compares the first resistance value with the second resistance value to determine whether or not a defect has occurred in the metal part within the battery cell. Here, the metal part may include at least one of a tab and a lead within the battery cell. Furthermore, the defect in the metal part may include at least one of a welding defect between tabs, a welding defect between a tab and a lead, and a broken tab.

[0059] In the case of metals, as the temperature increases, the number of electron collisions increases, increasing the atomic vibration frequency and resulting in an increase in resistance. According to one embodiment, if a welding defect (such as a welding defect between tabs or between a tab and a lead) or a complete disconnection (such as a disconnection of a tab) occurs in the metal part, contact resistance occurs between the tab or the tab and the lead, and the resistance may increase significantly (by approximately 1 to 3% in the case of a disconnection) compared to a normal battery cell. Therefore, the defect inspection device according to an embodiment of the present invention measures the change in impedance of the metal part in the battery cell before and after heating, thereby amplifying minute resistance values ​​such as weak welding and partial disconnection of the tab, which are difficult to detect, and enabling stable detection of these defects.

[0060] Meanwhile, the defect inspection device 5000 can include heat generation conditions according to the attribute information of the battery cell. Thus, when inducing heat generation in the metal part of the battery cell, the defect inspection device 5000 can transmit the heat generation conditions corresponding to the attribute information of the battery cell to the heating device 3000. As a result, the heating device 3000 can heat the metal part of the battery cell according to a predefined condition value that minimizes the temperature change of the electrolyte.

[0061] FIG. 2 is a block diagram of a control unit in a defect inspection device according to an embodiment of the present invention.

[0062] Referring to FIG. 2, the defect inspection device 5000 may include a memory 100 , a processor 200 , a transceiver 300 , an input interface device 400 , an output interface device 500 and a storage device 600 .

[0063] According to the embodiment, the components 100, 200, 300, 400, 500, and 600 included in the defect inspection device 5000 are connected by a bus 700 and can communicate with each other.

[0064] The memory 100 and the storage device 600 among the above configurations 100, 200, 300, 400, 500, and 600 of the defect inspection device 5000 may be configured with at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory 100 and the storage device 600 may be configured with at least one of a read only memory (ROM) and a random access memory (RAM).

[0065] Among other things, memory 100 may contain at least one instruction that is executed by processor 200 .

[0066] According to an embodiment, the at least one instruction may include an instruction to calculate a difference between resistance values ​​measured before and after heat generation of a metal part of a battery cell; and an instruction to compare the difference with a preset reference value to check whether a defect has occurred in the metal part.

[0067] Here, the instruction to calculate the difference in the resistance values ​​may include an instruction to obtain a first resistance value of the metal part, an instruction to induce heat generation in the metal part according to a heat generation condition, an instruction to obtain a second resistance value of the metal part in which heat generation is induced, and an instruction to compare the first resistance value and the second resistance value to calculate the difference value.

[0068] In this case, the heat generation condition may include at least one condition value for maintaining a temperature change of the electrolyte in the battery cell below a preset reference value.

[0069] In addition, the command to induce heat generation of the metal part according to the heat generation condition may include a command to induce heat generation of the metal part by charging / discharging the battery cell according to the heat generation condition.

[0070] For example, the heat generation condition may include at least one of a magnitude of a charge / discharge current, a charge / discharge time, and an external temperature for charging / discharging the battery cell.

[0071] At this time, the heat generation condition can be changed according to attribute information of the battery cell.

[0072] On the other hand, the resistance value may be the real part of the impedance value measured at a predefined frequency.

[0073] In addition, the command to inspect whether or not a defect has occurred in the metal part may include a command to determine that a defect has occurred in the metal part if the difference value is equal to or greater than the reference value, and a command to determine that the battery cell is normal if the difference value is less than the reference value.

[0074] The processor 200 may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which methods according to embodiments of the present invention are performed.

[0075] The processor 200 is capable of executing at least one program command stored in the memory 100, as described above.

[0076] FIG. 3 is a flow chart for explaining a method for inspecting battery cells for defects using a defect inspection device according to an embodiment of the present invention.

[0077] 3, the processor 200 in the defect inspection device 5000 may acquire a first resistance value measured from a battery cell to be inspected (S1000). Here, the battery cell may be a battery cell in which heat generation is not induced in a metal part.

[0078] The first resistance value may also be information about the real part of an impedance value corresponding to a predefined frequency. Here, the predefined frequency may be defined as a specific frequency equal to or higher than a predefined reference frequency. For example, the specific frequency may be 850 Hz, which is one of the frequencies in the high frequency range equal to or higher than the reference frequency of 600 Hz.

[0079] According to an embodiment, the processor 200 may receive impedance values ​​for each frequency from the impedance measuring device 1000 through the transceiver 300. Then, the processor 200 may obtain a first resistance value by checking real part information of the impedance measured at a predetermined frequency among the received impedance values.

[0080] According to another embodiment, the processor 200 can receive and acquire a first resistance value, which is the real part of the impedance value corresponding to a predefined frequency, from the impedance measuring device 1000 via the transceiver device 300.

[0081] Thereafter, the processor 200 can operate the heat generating device 3000 to induce heat generation in the metal part within the battery cell (S3000).

[0082] According to an embodiment, the processor 200 may transmit a heat generation condition and an operation signal to the heat generation device 3000 using the transceiver 300. Here, the heat generation condition may be a predefined condition value for minimizing a temperature change of the electrolyte in the battery cell. According to an embodiment, if the heat generation device 3000 is a charge / discharge device, the heat generation condition may include at least one of a magnitude of a charge / discharge current, a time of the charge / discharge current, and an external temperature, which are predefined for minimizing a temperature change of the electrolyte in the battery cell.

[0083] For example, the heating condition may be pre-stored in the memory 100 in the form of a table with at least one condition value corresponding to the attribute information of the battery cell. Thus, the processor 200 can obtain the heating condition corresponding to the attribute information of the battery cell to be inspected and transmit it to the heating device 3000.

[0084] Then, the processor 200 can obtain a second resistance value measured from the heated battery cell (S5000). In other words, the battery cell may be in a state where heat generation of a metal part in the battery cell is intentionally induced by the heat-generating device 3000.

[0085] The second resistance value may be information about the real part of an impedance value corresponding to a predetermined frequency. Here, the predetermined frequency may be defined as a specific frequency equal to or higher than a predetermined reference frequency. For example, the specific frequency may be 850 Hz, which is one of frequencies in a high frequency range equal to or higher than the reference frequency of 600 Hz.

[0086] According to one embodiment, the processor 200 may receive, via the transceiver 300, impedance values ​​for each frequency of the battery cell whose metal part is heated, measured from the impedance measuring device 1000. Thereafter, the processor 200 may check the real part information of the impedance measured at a predetermined frequency among the received impedance values ​​to obtain a second resistance value.

[0087] According to another embodiment, the processor 200 can receive, via the transceiver 300, a second resistance value, which is the real part of the impedance value corresponding to a predetermined frequency among the impedance measurement values ​​of the battery cell whose metal part has been heated, from the impedance measuring device 1000.

[0088] Thereafter, the processor 200 can compare the first resistance value with the second resistance value to determine whether or not there is a defect in the metal part in the battery cell (S7000).

[0089] More specifically, the processor 200 may calculate a difference between the first resistance value and the second resistance value. Then, the processor 200 may compare the difference with a predefined reference value. The reference value may vary depending on the number and size of tabs, which are metal parts within the battery cell. For example, the reference value may be 0.007 mΩ.

[0090] According to an embodiment, if the difference value is equal to or greater than the reference value, the processor 200 may determine that a defect has occurred in the metal part of the battery cell.

[0091] According to another embodiment, if the difference value is less than the reference value, the processor 200 may determine that there is no abnormality in the metal part of the battery cell.

[0092] Battery cell defect inspection method according to an experimental example of the present invention

[0093] FIG. 4 is a conceptual diagram of a defect inspection system for inspecting pouch-type battery cells according to an experimental example of the present invention.

[0094] As shown in Figure 4, normal and defective battery cells of the same model were prepared, each containing 20 tabs and provided in a pouch. Here, the defective battery cell was a battery cell in which a 35 mm break occurred in the tab.

[0095] First, a normal battery cell was fixed to a fixture in the form of a jig. Then, an AC voltage was applied to both ends of the electrodes of the normal battery cell using the impedance measuring device 1000. Then, while changing the frequency from 1 kHz to 400 Hz, the impedance value at a predetermined reference frequency was first measured before heat generation occurred.

[0096] Thereafter, a charge / discharge device was used as the heat generating device 3000 to confirm the heat generating conditions corresponding to the attribute information of the normal battery cells.

[0097] According to the heat generation conditions, the external temperature was set to 22°C, and charging and discharging were performed by applying a charging and discharging current of 60 A for 5 seconds each.

[0098] Thereafter, the impedance measuring device 1000 was used to measure the impedance value of the normal battery cell again at the predefined reference frequency for the second time.

[0099] Thereafter, the impedance values ​​of the defective battery cells were measured individually at a predefined reference frequency before and after heat generation under the same conditions as those of the normal battery cells.

[0100] Thereafter, the defect inspection device 5000 was used to inspect the normal battery cells and the defective battery cells for the presence or absence of defects in the metal parts.

[0101] FIG. 5 is an image of measuring the temperature of a defective battery cell during heat induction according to an experimental example of the present invention.

[0102] Referring to Figure 5, the average temperature of the entire tab, which is the metal part of a normal battery cell, after charging and discharging was measured to be 25.038°C, while the average temperature of the entire tab of a defective battery cell after charging and discharging was measured to be 26.393°C. In other words, it can be seen that the average temperature of the defective battery cell after charging and discharging is 1.355°C higher than the average temperature of a normal battery cell after charging and discharging.

[0103] FIG. 6 is a graph showing the impedance measurement results for each frequency of a normal battery cell before and after heat generation according to an experimental example of the present invention, FIG. 7 is a graph showing the impedance measurement results for each frequency of a defective battery cell before and after heat generation according to an experimental example of the present invention, and FIG. 8 is a table summarizing the resistance values ​​of a normal battery cell and a defective battery cell before and after heat generation according to an experimental example of the present invention.

[0104] Referring to Figures 6 to 8, the impedance measurement graphs for normal and defective battery cells by frequency show that there is a clear difference in the real part of the impedance before and after charging and discharging in the high frequency range above the reference frequency (fs).

[0105] Based on the values ​​of the real part of the impedance of a normal battery cell and a defective battery cell at a predetermined frequency, the difference between before and after heat generation through a charge / discharge device was examined. As a result, it was confirmed that the value of the real part of the impedance of a normal battery cell before charge / discharge was 0.862 mΩ, and the value of the real part of the impedance of a defective battery cell before charge / discharge was 0.866 mΩ. In other words, it was confirmed that the value of the real part of the impedance of a defective battery cell before charge / discharge was 0.004 mΩ larger than the value of the real part of the impedance of a normal battery cell before charge / discharge.

[0106] In addition, it was confirmed that the real part of the impedance of a normal battery cell after charging and discharging was 0.871 mΩ, while the real part of the impedance of a defective battery cell after charging and discharging was 0.881 mΩ, which was 0.01 mΩ larger.

[0107] In addition, it was confirmed that the increase in the real part of the impedance of a normal battery cell before and after charging and discharging was 0.009 mΩ, while the increase in the real part of the impedance of a defective battery cell before and after charging and discharging was 0.015 mΩ, which was larger by 0.006 mΩ.

[0108] Comparing the difference in impedance between normal and defective battery cells, it was confirmed that the change in the real part of the impedance measured after heat induction of the metal parts due to charging and discharging (0.01mΩ) was 2.5 times larger than the change in the real part of the impedance measured without any separate heat induction (0.004mΩ).In addition, it was confirmed that the difference in the change in the real part of the impedance before and after charging and discharging of normal and defective battery cells (0.006mΩ) was 1.5 times larger than the change in the real part of the impedance measured without any separate heat induction (0.004mΩ).

[0109] In short, it can be confirmed that the difference in impedance between a normal battery cell and a defective battery cell is greatest in the difference in the real part of the impedance measured in the reference frequency range after the heat generation of the metal parts.

[0110] Therefore, the battery cell defect inspection method according to the experimental example of the present invention enables highly accurate determination of defects in metal parts by intentionally inducing heat generation in the metal parts within the battery cell and then determining whether or not the metal parts of the battery cell are defective based on the amount of change in the real part of the impedance before and after the heat generation.

[0111] The battery cell defect inspection device and method, and the system including the same, according to the embodiments and experimental examples of the present invention have been described above.

[0112] The battery cell defect inspection device and method, and system including the same, according to the embodiments and experimental examples of the present invention use a heating device to induce heat in metal parts within a battery cell, and determine whether or not the metal parts within the battery cell are defective based on the change in impedance of the battery cell before and after heating. This increases the resistance value of the metal parts that have become defective due to heat, thereby improving the detection ability for even minor defects such as weak welding or partial breakage of tabs.

[0113] The operations of the methods according to the embodiments and experimental examples of the present invention can be embodied as a computer-readable program or code on a computer-readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored. In addition, the computer-readable recording medium can be distributed among computer systems connected via a network, so that the computer-readable program or code can be stored and executed in a distributed manner.

[0114] Furthermore, the computer-readable recording medium may include a hardware device specially configured to store and execute program instructions, such as a ROM, a RAM, a flash memory, etc. The program instructions may include not only machine language code, such as that produced by a compiler, but also high-level language code that can be executed by a computer using an interpreter, etc.

[0115] Some aspects of the invention have been described in the context of an apparatus, but they may also be described in terms of a corresponding method, where a block or apparatus corresponds to a method step or feature of a method step. Similarly, aspects described in the context of a method may be described in terms of a corresponding block or item or feature of a corresponding apparatus. Some or all of the method steps may be performed by (or using) a hardware apparatus, such as a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, one or more of the most important method steps may be performed by such an apparatus.

[0116] Although the present invention has been described above with reference to preferred embodiments, those skilled in the art will understand that various modifications and variations can be made to the present invention without departing from the spirit and scope of the present invention as set forth in the following claims. [Explanation of symbols]

[0117] 1000: Impedance measuring device 3000: Heat generating device 5000: Defective inspection equipment 100:Memory 200: Processor 300: Transmitter / receiver 400: Input interface device 500: Output interface device 600: Storage device 700: Bus

Claims

1. Calculating a difference between the resistance values ​​measured before and after inducing heat generation in the metal part of the battery cell; and a step of comparing the difference value with a preset reference value to inspect whether or not a defect has occurred in the metal portion;

2. The step of calculating the difference in resistance value includes: obtaining a first resistance value of the metal portion; inducing heat generation in the metal part according to a heat generation condition; Obtaining a second resistance value of the metal portion in which heat generation is induced; and The method for inspecting battery cells for defects according to claim 1 , further comprising the step of comparing the first resistance value with the second resistance value to calculate the difference value.

3. The heat generation conditions are:

3. The method of claim 2, further comprising at least one condition value for maintaining a temperature change of the electrolyte in the battery cell below a predetermined reference value.

4. The step of inducing heat generation in the metal part according to the heat generation condition includes: The method for inspecting battery cells for defects according to claim 2 , further comprising the step of inducing heat generation in the metal portion by charging and discharging the battery cell in accordance with the heat generation condition.

5. The heat generation conditions are: The method of claim 4 , wherein the method comprises determining at least one of a magnitude of a charge / discharge current, a charge / discharge time, and an external temperature for charging / discharging the battery cell.

6. The heat generation conditions are: The battery cell defect inspection method according to claim 3 , wherein the defect detection value is changed in accordance with the attribute information of the battery cell.

7. The resistance value is The method for inspecting battery cells for defects according to claim 1 , wherein the value is a real part of an impedance value measured at a predefined frequency.

8. The step of inspecting whether or not defects occur in the metal part includes: determining that a defect has occurred in the metal part when the difference value is equal to or greater than the reference value; and The method for inspecting a battery cell for defects according to claim 1 , further comprising the step of determining that the battery cell is normal if the difference value is less than the reference value.

9. memory; a processor that executes at least one instruction stored in the memory; The at least one instruction: An instruction to calculate a difference between resistance values ​​measured before and after inducing heat generation in a metal part of a battery cell; and The battery cell defect inspection device includes an instruction to compare the difference value with a preset reference value to inspect whether or not a defect has occurred in the metal portion.

10. The instruction to calculate the difference in resistance values ​​includes: instructions to obtain a first resistance value of the metal portion; an instruction to induce heating of the metal part according to a heating condition; instructions for obtaining a second resistance value of the metal portion in which heating is induced; and The battery cell defect inspection device according to claim 9 , further comprising an instruction to compare the first resistance value with the second resistance value and calculate the difference value.

11. The heat generation conditions are: The device for inspecting defects in a battery cell according to claim 10, further comprising at least one condition value for maintaining a temperature change of the electrolyte in the battery cell below a preset reference value.

12. The instruction to induce heating of the metal part in accordance with the heating condition includes: The battery cell defect inspection device according to claim 10 , further comprising a command to charge / discharge the battery cell in accordance with the heat generation condition, thereby inducing heat generation in the metal portion.

13. The heat generation conditions are: The battery cell defect inspection device according to claim 12 , wherein the battery cell defect inspection device includes at least one of a magnitude of a charge / discharge current, a charge / discharge time, and an external temperature for charging / discharging the battery cell.

14. The heat generation conditions are: The battery cell defect inspection device according to claim 11 , wherein the defect detection value is changed in accordance with the attribute information of the battery cell.

15. The resistance value is The battery cell defect inspection device according to any one of claims 9 to 14, wherein the impedance is a real part of an impedance value measured at a predefined frequency.

16. The command to inspect the metal part for defects is an instruction to determine that a defect has occurred in the metal part if the difference value is equal to or greater than the reference value; and The device for inspecting a battery cell for defects according to claim 9 , further comprising an instruction for determining that the battery cell is normal if the difference value is less than the reference value.

17. an impedance measuring device for measuring the resistance of a battery cell; a heat generating device for inducing heat generation in a metal portion of the battery cell; and a battery cell defect inspection device that inspects whether or not defects occur in the metal parts of the battery cells; The battery cell defect inspection device includes: Calculating a difference between the resistance values ​​measured before and after the heat generation induction of the metal part by the impedance measuring device; A battery cell defect inspection system that compares the difference value with a preset reference value to inspect whether or not defects have occurred in the metal part.

18. The battery cell defect inspection device includes: obtaining a first resistance value of the metal part from the impedance measuring device before the heat generation of the metal part; transmitting a heat generation condition to the heat generating device to induce heat generation in the metal part; obtaining a second resistance value of the metal part in which heat generation is induced from the impedance measuring device; 18. The battery cell defect inspection system according to claim 17, wherein a difference between the first resistance value and the second resistance value is compared with the reference value to inspect whether or not a defect has occurred in the metal portion.

19. The heat generation conditions are:

20. The system for inspecting a battery cell for defects according to claim 18, further comprising at least one condition value for maintaining a temperature change of the electrolyte in the battery cell below a preset reference value.

20. The battery cell defect inspection system according to claim 17 , wherein the heat generating device includes a charging / discharging device.

21. The resistance value is 21. The battery cell defect inspection system according to claim 17, wherein the impedance is a real part of an impedance value measured at a predefined frequency.

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