Apparatus and method for inspecting defect of battery cell, and system comprising same

Abstract

An apparatus and a method for inspecting a defect of a battery cell, and a system comprising same, according to an embodiment and an experimental example of the present invention, can calculate a difference value of resistance values measured in a metal part before and after heat generation with respect to the battery cell, and compare the difference value with a preset reference value to determine whether a defect occurs in the metal part in the battery cell.

Description

Device and method for inspecting defects in battery cells, and system including the same

[0001] This application claims the benefit of Korean Patent Application No. 10-2023-0077226 filed with the Korean Intellectual Property Office on June 16, 2023, the entire disclosure of which is incorporated herein by reference.

[0002] The present invention relates to a device and method for inspecting defects in a battery cell, and a system including the same, and more particularly, to a device and method for inspecting defects occurring in a metal part of a battery cell, and a system including the same.

[0003] As fossil fuels deplete and concerns about environmental pollution grow, the importance of environmentally friendly alternative energy sources is growing. Among various alternative energy sources, demand for rechargeable lithium secondary batteries is rapidly increasing.

[0004] Lithium secondary batteries are being used in a wide range of industries, from mobile devices to automobiles, robots, and energy storage devices, as a response to environmental regulations and high oil prices. Consequently, lithium batteries are vulnerable to external shocks and vibrations.

[0005] Therefore, lithium batteries require defect inspection to ensure high performance and stability. In particular, defects in the metal parts of the battery, which are electrically connected to the outside world, can significantly degrade performance and safety. Therefore, defect inspection of these metal parts is essential.

[0006] Typically, defect inspection of metal parts may include tab break inspection and weld defect inspection.

[0007] Conventional defect inspection of metal parts involves disassembling manufactured battery cells and then performing a vision inspection, or using CT scanning for non-destructive testing to visually determine whether there are any defects.

[0008] However, visually assessing metal defects has the disadvantage of being difficult to accurately assess due to the vague criteria for assessment. Furthermore, the method of inspecting metal defects using CT scans suffers from the long processing times required for both imaging and assessment.

[0009] Recently, inspection methods using probe pins to measure resistance between weld surfaces have been utilized to determine defects. However, this welding inspection method using probe pins has the disadvantage of a high rate of false detection due to the formation of warpage in the weld surface caused by welding, making probe pin contact difficult. Furthermore, in the case of defects such as weak welds and partial tab disconnection, the resistance changes are minimal, leading to false detection of normal battery cells.

[0010] The purpose of the present invention to solve the above problems is to provide a method for inspecting defects in a battery cell.

[0011] Another object of the present invention to solve the above problems is to provide a device for inspecting defects in a battery cell.

[0012] Another object of the present invention to solve the above problems is to provide a system for inspecting defects in battery cells.

[0013] A method for inspecting a defect in a battery cell according to one embodiment of the present invention for achieving the above object includes a step of calculating a difference value between resistance values ​​measured before and after inducing heat generation in a metal portion of a battery cell, and a step of inspecting whether a defect has occurred in the metal portion by comparing the difference value with a preset reference value.

[0014] Here, the step of calculating the difference between the resistance values ​​may include the step of obtaining a first resistance value of the metal portion, the step of inducing heat generation in the metal portion according to a heat generation condition, the step of obtaining a second resistance value of the metal portion in which heat generation is induced, and the step of calculating the difference value by comparing the first resistance value and the second resistance value.

[0015] At this time, the heating condition may include at least one condition value that ensures that the temperature change of the electrolyte in the battery cell is maintained below a preset reference size.

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

[0017] For example, the above-mentioned heating condition may include at least one of the size of the charge / discharge current, the charge / discharge time, and the external temperature for charging / discharging the battery cell.

[0018] At this time, the above heating conditions can be changed according to the property information of the battery cell.

[0019] Meanwhile, the above resistance value may be a real part value of an impedance value measured at a predetermined frequency.

[0020] In addition, the step of checking whether 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 greater than or equal to 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]

[0022] According to another embodiment of the present invention for achieving the above object, a device for inspecting a defect in a battery cell includes a memory, a processor for executing at least one command stored in the memory, and the at least one command includes a command for calculating a difference value between resistance values ​​measured before and after inducing heat generation in a metal portion of a battery cell; and a command for inspecting whether a defect has occurred in the metal portion by comparing the difference value with a preset reference value.

[0023] Here, the command to calculate the difference between the resistance values ​​may include a command to obtain a first resistance value of the metal part, a command to induce heat generation in the metal part according to a heat generation condition, a command to obtain a second resistance value of the metal part in which heat generation is induced, and a command to compare the first resistance value and the second resistance value to calculate the difference value.

[0024] At this time, the heating condition may include at least one condition value that ensures that the temperature change of the electrolyte in the battery cell is maintained below a preset reference size.

[0025] In addition, the command to induce heat generation in the metal part according to the heat generation condition may include a command to induce heat generation in the metal part by performing charging and discharging on the battery cell according to the heat generation condition.

[0026] For example, the above-mentioned heating condition may include at least one of the size of the charge / discharge current, the charge / discharge time, and the external temperature for charging / discharging the battery cell.

[0027] At this time, the above heating conditions can be changed according to the property information of the battery cell.

[0028] Meanwhile, the above resistance value may be a real part value of an impedance value measured at a predetermined frequency.

[0029] In addition, the command to check whether 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 greater than or equal to the reference value, and a command to determine that the battery cell is normal if the difference value is less than the reference value.

[0030]

[0031] According to another embodiment of the present invention for achieving the above object, a system for inspecting a defect in a battery cell includes an impedance measuring device for measuring a resistance value of a battery cell, a heating device for inducing heating of a metal portion of the battery cell, and a defect inspection device for inspecting whether a defect has occurred in the metal portion of the battery cell, wherein the defect inspection device for the battery cell calculates a difference value between resistance values ​​measured before and after inducing heating of the metal portion by the impedance measuring device, and compares the difference value with a preset reference value to inspect whether a defect has occurred in the metal portion.

[0032] At this time, the defect inspection device of the battery cell can obtain a first resistance value of the metal part from the impedance measuring device before inducing heat generation in the metal part, transmit a heat generation condition to the heat generation device to induce heat generation in the metal part, obtain a second resistance value of the metal part where heat generation is induced from the impedance measuring device, and compare a difference value between the first resistance value and the second resistance value with the reference value to inspect whether a defect has occurred in the metal part.

[0033] Here, the heating condition may include at least one condition value that ensures that the temperature change of the electrolyte in the battery cell is maintained below a preset reference size.

[0034] Meanwhile, the heating device may include a charging / discharging device.

[0035] Additionally, the resistance value may be a real part of an impedance value measured at a predetermined frequency.

[0036] A device and method for inspecting a battery cell for defects according to embodiments and experimental examples of the present invention, and a system including the same, induce heat generation in a battery cell as a test subject and compare impedance measurement values ​​before and after the generation, thereby increasing the resistance change of a metal part inside a defective battery cell due to the heat generation, thereby enabling a highly reliable inspection for defects.

[0037] FIG. 1 is a block diagram of a battery cell defect inspection system according to an embodiment of the invention.

[0038] Figure 2 is a block diagram of a control unit in a defect inspection device according to an embodiment of the present invention.

[0039] FIG. 3 is a flowchart for explaining a method for inspecting a battery cell for defects using a defect inspection device according to an embodiment of the present invention.

[0040] FIG. 4 is a conceptual diagram of a defect inspection system for inspecting a pouch-shaped battery cell according to an experimental example of the present invention.

[0041] Figure 5 is an image showing the temperature of a defective battery cell measured when heat generation is induced according to an experimental example of the present invention.

[0042] Figure 6 is a graph showing the results of impedance measurement by frequency of a normal battery cell before and after heating according to an experimental example of the present invention.

[0043] Figure 7 is a graph showing the results of impedance measurement by frequency of a defective battery cell before and after heating according to an experimental example of the present invention.

[0044] Figure 8 is a table summarizing the resistance values ​​of normal battery cells and defective battery cells before and after heating according to an experimental example of the present invention.

[0045] 1000: Impedance measuring device 3000: Heating device

[0046] 5000: Defect Inspection Device

[0047] 100: Memory 200: Processor

[0048] 300: Transmitter / receiver device 400: Input interface device

[0049] 500: Output interface device 600: Storage device

[0050] 700: Bus

[0051] The present invention is susceptible to various modifications and embodiments. Specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention. Throughout the description of each drawing, similar reference numerals have been used to designate similar components.

[0052] Terms such as "first," "second," "A," and "B" may be used to describe various components, but these components should not be limited by these terms. These terms are used solely to distinguish one component from another. For example, without departing from the scope of the present invention, the first component could be referred to as the "second component," and similarly, the second component could also be referred to as the "first component." The term "and / or" includes any combination of multiple related items listed or any one of multiple related items listed.

[0053] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0054] The terminology used in this application is only used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, it should be understood that the terms "comprise" or "have" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0055] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0056] Hereinafter, a preferred embodiment according to the present invention will be described in detail with reference to the attached drawings.

[0057]

[0058] Fig. 1 is a block diagram of a battery cell defect inspection system according to an embodiment of the invention.

[0059] 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 a battery cell that is an inspection target.

[0060] To be more specific, the battery cell defect inspection system (S) may include an impedance measuring device (Electrochemical Impedance Spectroscopy; EIS, 1000), a heating device (3000), and a battery cell defect inspection device (5000).

[0061] The impedance measuring device (1000) can measure the resistance values ​​of a battery cell before and after heating.

[0062] To explain in more detail according to an embodiment, the impedance measuring device (1000) can be connected to the positive and negative poles of the battery cell, which is the subject of inspection, respectively.

[0063] For example, the battery cell may be positioned on a fixing member including a plurality of measuring pins. More specifically, the battery cell may be positioned on the fixing member with the positive and negative electrodes each in contact with one end of the plurality of measuring pins. Accordingly, the impedance measuring device (1000) may be connected to the other ends of the plurality of measuring pins, each of which has one end in contact with the positive and negative electrodes of the battery cell. Accordingly, the impedance measuring device (1000) may be electrically connected to the positive and negative electrodes of the battery cell, respectively. Here, the shape of the fixing member may be provided in various shapes that can improve the fixing force depending on the shape of the battery cell to be measured, such as a cylindrical shape, a pouch shape, a stack shape, etc.

[0064] Thereafter, the impedance measuring device (1000) can apply an AC voltage or AC current to the battery cell before and after heating. Accordingly, the impedance measuring device (1000) can measure changes in the amplitude and phase of the AC voltage or AC current passing through the battery cell, thereby calculating impedance values ​​for each frequency. For example, the AC voltage or AC current can be provided in the form of a sine wave.

[0065] The heating device (3000) may be a device that induces heating of a metal portion within the battery cell. More specifically, the heating device (3000) may be electrically or physically connected to the battery cell and may induce heating of the metal portion according to predetermined heating conditions. Here, the heating conditions may be condition setting information for minimizing temperature changes of an electrolyte within the battery cell.

[0066] In other words, the battery cell defect inspection system according to an embodiment of the present invention can induce heat generation limited to metal parts within the battery cell, so as to minimize temperature changes in the electrolyte of the battery cell, depending on the heat generation conditions. Accordingly, the defect inspection system can prevent the occurrence of side reactions due to temperature changes in the electrolyte during defect inspection of the battery cell.

[0067] Meanwhile, heating conditions may vary depending on the battery cell's property information. For example, the battery cell's property information may include factors that determine the battery model, such as the type, metal material, and number of tabs.

[0068] 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 the other ends of a plurality of measuring pins, each of which has one end in contact with the positive and negative poles of the battery cell, similar to the impedance measuring device (1000). In other words, the charging / discharging device may be electrically connected to the positive and negative poles of the battery cell, respectively. Thereafter, the charging / discharging device may charge / discharge the battery cell according to a predetermined heating condition. Accordingly, a metal part within the battery cell may be heated. At this time, the heating condition may include at least one condition information among the magnitude of the charging / discharging current, the time of the charging / discharging current, and the external temperature 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 the tabs, which are metal parts within the battery cell.

[0069] The heating device (3000) is not limited to the disclosed charging / discharging device, and can be applied to various devices capable of inducing heat generation in a metal part within the battery cell.

[0070] The defect inspection device (5000) can be linked with at least one of the impedance measurement device (1000) and the heating device (3000). Accordingly, the defect inspection device (5000) can obtain the first resistance value and the second resistance value measured before and after heating of the battery cell from the impedance measurement device (1000).

[0071] According to an embodiment, the first resistance value may be the real part of an impedance value corresponding to a predetermined frequency among the frequency-dependent impedance values ​​of the impedance measuring device (1000) measured for the battery cell before heating.

[0072] Additionally, the second resistance value may be the real part of an impedance value corresponding to a predetermined frequency among the impedance values ​​for each frequency of the impedance measuring device (1000) measured after heating the battery cell.

[0073] Here, the defined frequency can be defined as a specific frequency higher than a defined reference frequency. For example, the first resistance value and the second resistance value can be the real part of the impedance value at 850 Hz, which is one of the frequencies in the high-frequency range higher than the reference frequency of 600 Hz.

[0074] Thereafter, the defect inspection device (5000) can compare the first resistance value and the second resistance value to determine whether a defect has occurred in the metal portion within the battery cell. Here, the metal portion may include at least one of a tab and a lead within the battery cell. In addition, the defect in the metal portion may include at least one of a welding defect between tabs, a welding defect between a tab and a lead, and a disconnection of a tab.

[0075] In the case of metal, as the temperature increases, the number of collisions of electrons increases, the vibration frequency of atoms increases, and the resistance value may increase. At this time, according to one embodiment, if a welding defect (welding defect between tabs or welding defect between tabs and leads, etc.) or a complete disconnection (tab disconnection, etc.) occurs in the metal part, a contact resistance occurs between the tabs or the tabs and leads, and the resistance value may increase by a greater amount (about 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 can measure the impedance change of the metal part in the battery cell before and after heating, thereby amplifying the micro resistance value of weak welding and tab partial disconnection that are difficult to detect, thereby enabling stable defect detection of these.

[0076] Meanwhile, the defect inspection device (5000) may include heating conditions according to the attribute information of the battery cell. Accordingly, when heating is induced in a metal portion within the battery cell, the defect inspection device (5000) may transmit heating conditions corresponding to the attribute information of the battery cell to the heating device (3000). Accordingly, the heating device (3000) may heat the metal portion of the battery cell at predefined condition values ​​that minimize temperature changes in the electrolyte.

[0077]

[0078] Figure 2 is a block diagram of a control unit in a defect inspection device according to an embodiment of the present invention.

[0079] Referring to FIG. 2, the defect inspection device (5000) may include a memory (100), a processor (200), a transmission / reception device (300), an input interface device (400), an output interface device (500), and a storage device (600).

[0080] According to an embodiment, each of the components (100, 200, 300, 400, 500, 600) included in the defect inspection device (5000) is connected by a bus (bus, 700) and can communicate with each other.

[0081] Among the above components (100, 200, 300, 400, 500, 600) of the defect inspection device (5000), the memory (100) and the storage device (600) 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).

[0082] Among these, the memory (100) may include at least one command executed by the processor (200).

[0083] According to an embodiment, at least one command may include a command to calculate a difference value between resistance values ​​measured before and after inducing heat generation in a metal portion, targeting a battery cell; and a command to compare the difference value with a preset reference value to check whether a defect has occurred in the metal portion.

[0084] Here, the command to calculate the difference between the resistance values ​​may include a command to obtain a first resistance value of the metal part, a command to induce heat generation in the metal part according to a heat generation condition, a command to obtain a second resistance value of the metal part in which heat generation is induced, and a command to compare the first resistance value and the second resistance value to calculate the difference value.

[0085] At this time, the heating condition may include at least one condition value that ensures that the temperature change of the electrolyte in the battery cell is maintained below a preset reference size.

[0086] In addition, the command to induce heat generation in the metal part according to the heat generation condition may include a command to induce heat generation in the metal part by performing charging and discharging on the battery cell according to the heat generation condition.

[0087] For example, the above-mentioned heating condition may include at least one of the size of the charge / discharge current, the charge / discharge time, and the external temperature for charging / discharging the battery cell.

[0088] At this time, the above heating conditions can be changed according to the property information of the battery cell.

[0089] Meanwhile, the above resistance value may be a real part value of an impedance value measured at a predetermined frequency.

[0090] In addition, the command to check whether 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 greater than or equal to the reference value, and a command to determine that the battery cell is normal if the difference value is less than the reference value.

[0091] The processor (200) may mean 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.

[0092] As described above, the processor (200) can execute at least one program command stored in the memory (100).

[0093]

[0094] FIG. 3 is a flowchart for explaining a method for inspecting a battery cell for defects using a defect inspection device according to an embodiment of the present invention.

[0095] Referring to FIG. 3, the processor (200) within the defect inspection device (5000) can obtain a first resistance value measured from a battery cell that is a subject of inspection (S1000). Here, the battery cell may be a battery cell in which no heat generation is induced in the metal portion.

[0096] Additionally, the first resistance value may be real-valued information of an impedance value corresponding to a predetermined frequency. Here, the predetermined frequency may be defined as a specific frequency higher than a predetermined reference frequency. For example, the specific frequency may be 850 Hz, which is one of the frequencies in the high-frequency range higher than the reference frequency of 600 Hz.

[0097] According to one embodiment, the processor (200) may receive impedance values ​​for each frequency from the impedance measuring device (1000) through the transceiver device (300). Thereafter, 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.

[0098] According to another embodiment, the processor (200) may receive and obtain a first resistance value, which is a real part of an impedance value corresponding to a predetermined frequency, from an impedance measuring device (1000) through a transceiver device (300).

[0099] Thereafter, the processor (200) can operate the heating device (3000) to induce heating of the metal part within the battery cell (S3000).

[0100] 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 to minimize a temperature change of the electrolyte within the battery cell. According to an embodiment, when the heat generation device (3000) is a charge / discharge device, the heat generation condition may include at least one of a size of a charge / discharge current, a time of the charge / discharge current, and an external temperature, which are predefined to minimize a temperature change of the electrolyte within the battery cell.

[0101] For example, a heating condition may be pre-stored in the memory (100) in the form of a table with at least one condition value according to the attribute information of the battery cell. Accordingly, the processor (200) may obtain a heating condition corresponding to the attribute information of the battery cell being inspected and transmit it to the heating device (3000).

[0102] Thereafter, 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 heating of the metal portion within the battery cell is intentionally induced by the heating device (3000).

[0103] The second resistance value may be the real part information of the impedance value corresponding to a predetermined frequency. Here, the predetermined frequency may be defined as a specific frequency higher than a predetermined reference frequency. For example, the specific frequency may be 850 Hz, which is one of the frequencies in the high-frequency range higher than the reference frequency of 600 Hz.

[0104] According to one embodiment, the processor (200) can receive, through the transceiver (300), the frequency-dependent impedance value of the battery cell in which the metal part is heated, measured from the impedance measuring device (1000). Thereafter, the processor (200) can obtain a second resistance value by checking the real part information of the impedance measured at a predetermined frequency among the received impedance values.

[0105] According to another embodiment, the processor (200) may receive, through the transceiver (300), from the impedance measuring device (1000), a second resistance value, which is a real part of an impedance value corresponding to a predetermined frequency among impedance measurement values ​​of the battery cell in which the metal part is heated.

[0106] Thereafter, the processor (200) can determine whether there is a defect in the metal part within the battery cell by comparing the first resistance value and the second resistance value (S7000).

[0107] More specifically, the processor (200) can calculate a difference between the first resistance value and the second resistance value. Thereafter, the processor (200) can compare the difference with a predetermined reference value. Here, the reference value may vary depending on the number and size of the metal parts and tabs within the battery cell. For example, the reference value may be 0.007 mΩ.

[0108] According to one embodiment, if the difference value is greater than or equal to the reference value, the processor (200) may determine that a defect has occurred in the metal portion of the battery cell.

[0109] According to another embodiment, if the difference value is less than the reference value, the processor (200) can determine that there is no abnormality in the metal part of the battery cell.

[0110]

[0111] Method for inspecting defects in battery cells according to an experimental example of the present invention

[0112] FIG. 4 is a conceptual diagram of a defect inspection system for inspecting a pouch-shaped battery cell according to an experimental example of the present invention.

[0113] As shown in Fig. 4, normal and defective battery cells of the same model, each containing 20 tabs and provided in a pouch form, were prepared. Here, the defective battery cell is a battery cell with a 35 mm short circuit in the tab.

[0114] First, a normal battery cell was fixed to a jig-shaped fixture. Then, using an impedance measuring device (1000), an AC voltage was applied to both electrodes of the normal battery cell. Then, while varying the frequency from 1 kHz to 400 Hz, the impedance value at a predefined reference frequency before heat generation was measured for the first time.

[0115] Afterwards, using a charging / discharging device as a heating device (3000), the heating conditions corresponding to the attribute information of the normal battery cell were confirmed.

[0116] According to the heating conditions, the external temperature was set to 22℃, and charging and discharging were performed by applying a charge and discharge current of 60A for 5 seconds each.

[0117] Afterwards, using the impedance measuring device (1000), the impedance value at the predefined reference frequency of the normal battery cell was measured a second time.

[0118] Thereafter, the impedance values ​​of the defective battery cells before and after heating were individually measured at a predefined reference frequency under the same conditions as the normal battery cells.

[0119] Afterwards, using a defect inspection device (5000), the occurrence of defects in the metal parts of normal and defective battery cells was inspected.

[0120]

[0121] Figure 5 is an image showing the temperature of a defective battery cell measured when heat generation is induced according to an experimental example of the present invention.

[0122] Referring to Fig. 5, the average temperature of the entire tab, which is the metal part of a normal battery cell after charge and discharge, was measured to be 25.038℃, and the average temperature of the entire tab of a defective battery cell after charge and discharge was measured to be 26.393℃. In other words, it can be confirmed that the average temperature of a defective battery cell after charge and discharge is 1.355℃ higher than the average temperature of a normal battery cell after charge and discharge.

[0123]

[0124] FIG. 6 is a graph showing the results of impedance measurement by frequency of a normal battery cell before and after heating according to an experimental example of the present invention, FIG. 7 is a graph showing the results of impedance measurement by frequency of a defective battery cell before and after heating 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 heating according to an experimental example of the present invention.

[0125] Referring to FIGS. 6 to 8, when examining the impedance measurement graphs for a normal battery cell and a defective battery cell by frequency, it can be confirmed 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).

[0126] Accordingly, based on the values ​​of the real part of the impedance at a predetermined frequency in a normal battery cell and a defective battery cell, the difference values ​​before and after inducing heat generation through a charge / discharge device were examined. As a result, it was confirmed that the real part of the impedance of the normal battery cell before charge / discharge was 0.862 mΩ, and the real part of the impedance of the defective battery cell before charge / discharge was 0.866 mΩ. In other words, it was confirmed that the real part of the impedance of the defective battery cell before charge / discharge was 0.004 mΩ larger than the real part of the impedance of the normal battery cell before charge / discharge.

[0127] In addition, the real part value of the impedance of a normal battery cell after charge and discharge was 0.871 mΩ, and the real part value of the impedance of a defective battery cell before charge and discharge was 0.881 mΩ, confirming that the real part value of the impedance of the defective battery cell after charge and discharge was 0.01 mΩ larger.

[0128] In addition, the increase in the real part of the impedance of a normal battery cell before and after charging and discharging was 0.009 mΩ, and the increase in the real part of the impedance of a defective battery cell before and after charging and discharging was 0.015 mΩ, confirming that the increase in the real part of the impedance of the defective battery cell was 0.006 mΩ greater.

[0129] Accordingly, as a result of comparing the impedance difference between a normal battery cell and a defective battery cell, it can be confirmed that the change in the real part of the impedance measured after inducing heat generation in the metal part due to charge and discharge (0.01 mΩ) increased by 2.5 times compared to the change in the real part of the impedance measured without a separate heat generation induction (0.004 mΩ). In addition, it can be confirmed that the difference in the change in the real part of the impedance before and after charge and discharge of each of the normal battery cell and the defective battery cell (0.006 mΩ) also increased by 1.5 times compared to the change in the real part of the impedance measured without a separate heat generation induction (0.004 mΩ).

[0130] In summary, the difference in impedance between a normal battery cell and a defective battery cell can be confirmed to be the greatest in the difference in the real part of the impedance measured in the reference frequency range after heat generation in the metal part.

[0131] Therefore, the method for inspecting a defect in a battery cell according to an experimental example of the present invention intentionally induces heat generation in a metal part within a battery cell, and then determines whether the metal part of the battery cell is defective based on the amount of change in the real part of the impedance before and after the heat generation, thereby enabling highly accurate determination of defects in the metal part.

[0132]

[0133] The above has described a device and method for inspecting a battery cell for defects according to embodiments and experimental examples of the present invention, and a system including the same.

[0134] A device and method for inspecting defects in a battery cell according to embodiments and experimental examples of the present invention, and a system including the same, induces heating of a metal part within a battery cell using a heating device, and determines whether a metal part within the battery cell is defective based on the amount of change in impedance of the battery cell before and after heating, thereby increasing the resistance value of the metal part where a defect occurs due to heating, thereby improving the detection ability even for micro-defects such as weak welding or tab disconnection.

[0135]

[0136] The operations of the methods according to the embodiments and experimental examples of the present invention can be implemented as computer-readable programs or codes on a computer-readable recording medium. Computer-readable recording media include all types of recording devices that store data that can be read by a computer system. Furthermore, computer-readable recording media can be distributed across network-connected computer systems, allowing computer-readable programs or codes to be stored and executed in a distributed manner.

[0137] Additionally, the computer-readable recording medium may include hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, etc. The program instructions may include not only machine language codes produced by a compiler, but also high-level language codes that can be executed by a computer using an interpreter, etc.

[0138] While some aspects of the present invention have been described in the context of a device, they may also represent a description of a corresponding method, wherein a block or device corresponds to a method step or a feature of a method step. Similarly, aspects described in the context of a method may also be described as a corresponding block or item or a feature of a corresponding device. Some or all of the method steps may be performed by (or using) a hardware device, such as, for example, a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, one or more of the most significant method steps may be performed by such a device.

[0139] Although the present invention has been described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various modifications and changes may be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below.

Claims

1. A step for calculating the difference between the resistance values ​​measured before and after inducing heat generation in the metal part of the battery cell; and A method for inspecting defects in a battery cell, comprising a step of comparing the difference value with a preset reference value to inspect whether a defect has occurred in the metal part.

2. In claim 1, The step of calculating the difference between the above resistance values ​​is: A step of obtaining a first resistance value of the metal portion; A step of inducing heat generation in the metal part according to the heat generation conditions; A step of obtaining a second resistance value of the metal part in which heat generation is induced; and A method for inspecting a battery cell for defects, comprising the step of comparing the first resistance value and the second resistance value to calculate the difference value.

3. In claim 1, The above heating conditions are: A method for inspecting a battery cell for defects, comprising at least one condition value that ensures that a temperature change of an electrolyte within the battery cell is maintained below a preset standard size.

4. In claim 2, The step of inducing heat generation in the metal part according to the above heat generation conditions is: A method for inspecting defects in a battery cell, comprising a step of performing charging and discharging on the battery cell according to the above-mentioned heating conditions, thereby inducing heat generation in the metal part.

5. In claim 4, The above heating conditions are: A method for inspecting a defect in a battery cell, comprising at least one of the size of a charge / discharge current, a charge / discharge time, and an external temperature for charging / discharging the battery cell.

6. In claim 3, The above heating conditions are: A method for inspecting defects in a battery cell, which changes according to the property information of the battery cell.

7. In claim 1, The above resistance value is, A method for inspecting defects in a battery cell, the real part of the impedance value measured at a predetermined frequency.

8. In claim 1, The step of inspecting whether there is a defect in the above metal part is as follows: A step of determining that a defect has occurred in the metal part when the difference value is greater than or equal to the reference value; and A method for inspecting a battery cell for defects, comprising a step of determining that the battery cell is normal if the difference value is less than the reference value.

9. Memory; a processor for executing at least one instruction stored in the memory; At least one of the above commands, A command to calculate the difference between the resistance values ​​measured before and after inducing heat generation of a metal part for a battery cell; and A battery cell defect inspection device, comprising a command to compare the difference value with a preset reference value and inspect whether a defect has occurred in the metal part.

10. In claim 9, The command to calculate the difference between the above resistance values ​​is: A command to obtain a first resistance value of the above metal part, A command to induce heat generation in the metal part according to the heat generation conditions; A command to obtain a second resistance value of the metal part in which heat is induced, and A device for inspecting a battery cell for defects, comprising a command to compare the first resistance value and the second resistance value and calculate the difference value.

11. In claim 9, The above heating conditions are: A device for inspecting defects in a battery cell, comprising at least one condition value that ensures that a temperature change in an electrolyte within the battery cell is maintained below a preset reference size.

12. In claim 10, A command to induce heat generation in the metal part according to the above heat generation conditions is: A device for inspecting defects in a battery cell, comprising a command to perform charging and discharging on the battery cell according to the above-mentioned heating conditions, thereby inducing heating in the metal part.

13. In claim 12, The above heating conditions are: A device for inspecting defects in a battery cell, comprising at least one of the size of a charge / discharge current, a charge / discharge time, and an external temperature for charging / discharging the battery cell.

14. In claim 11, The above heating conditions are: A device for inspecting defects in a battery cell, which changes according to the property information of the battery cell.

15. In claim 9, The above resistance value is, A device for inspecting defects in battery cells, which is the real number of impedance values ​​measured at a predetermined frequency.

16. In claim 9, The command to inspect for defects in the above metal part is: A command to determine that a defect has occurred in the metal part if the difference value is greater than or equal to the reference value, and A device for inspecting a battery cell for defects, comprising a command for determining that the battery cell is normal when the difference value is less than the reference value.

17. Impedance measuring device for measuring the resistance value of battery cells; A heating device that induces heating of the metal part of the battery cell; and Including a device for inspecting defects in a battery cell to determine whether a defect occurs in a metal part of the battery cell, The above battery cell defect inspection device is, The difference value between the resistance values ​​measured before and after the heating of the metal part is calculated by the impedance measuring device, A battery cell defect inspection system that compares the above difference value with a preset reference value to inspect whether a defect has occurred in the metal part.

18. In claim 17, The above battery cell defect inspection device is, Before inducing heat generation in the metal part from the impedance measuring device, the first resistance value of the metal part is obtained, By transmitting the heating condition to the above heating device, heating is induced in the metal part, From the above impedance measuring device, the second resistance value of the metal part in which heat generation is induced is obtained, A battery cell defect inspection device that compares the difference between the first resistance value and the second resistance value with the reference value to inspect whether a defect has occurred in the metal part.

19. In claim 18, The above heating conditions are: A battery cell defect inspection system comprising at least one condition value that ensures that a temperature change of an electrolyte within the battery cell is maintained below a preset reference size.

20. In claim 17, The above heating device is a battery cell defect inspection system including a charging / discharging device.

21. In claim 17, The above resistance value is, A battery cell defect inspection system, which is a real-valued impedance value measured at a predetermined frequency.

Images