Apparatus and method for inspecting defects of battery cells and system including the same

Abstract

According to an embodiment and an experimental example of the present invention, an apparatus and a method for inspecting a defect of a battery cell, and a system including the same, can calculate a difference between resistance values measured before and after heating of a metal portion for a battery cell; and comparing the difference value with a preset reference value to determine whether a defect occurs in the metal part of the battery cell.

Description

Technical Field

[0001] This application claims priority to and the benefit of Korean Patent Application No. 10-2023-0077226 filed in the Korean Intellectual Property Office on June 16, 2023, the entire contents of which are incorporated herein by reference.

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

[0003] With the depletion of fossil fuels and the increasing concern about environmental pollution, the demand for secondary batteries as environmentally friendly alternative energy sources is rapidly increasing. Among various alternative energy sources, the demand for rechargeable lithium secondary batteries is rapidly increasing.

[0004] As a response to today's environmental regulations and high oil prices, lithium secondary batteries are being used in a variety of industrial fields from mobile applications to vehicles, robots, and energy storage devices. In addition, lithium batteries are easily affected by external shocks, vibrations, etc.

[0005] Therefore, defect inspection is essential for lithium batteries to ensure high performance and stability. Among them, if defects occur in the metal part of the battery that is electrically connected to the outside, the performance and safety are greatly reduced, so it is necessary to inspect the defects of the metal part.

[0006] Generally, defect inspection of metal parts may include inspection of joint disconnection and inspection of welding defects.

[0007] Conventional defect inspection of metal parts may involve disassembling already manufactured battery cells and performing visual inspections, or non-destructive inspections using CT imaging to visually identify defects.

[0008] However, when visually determining whether the metal part is defective, there is a disadvantage that it is difficult to accurately judge the quality because the judgment standard is unclear. Additionally, the method of inspecting defects in the metal part by CT imaging has the disadvantage of requiring a long time for imaging and determination.

[0009] Recently, an inspection method for determining defects by measuring the resistance between welding surfaces using a probe has been used. However, the welding inspection method using a probe has a disadvantage in that the welding surface is bent due to welding, making contact with the probe difficult, resulting in a high incidence of false detection. In addition, in the case of defects such as weak welding and partial disconnection of the joint, the change in resistance is small, resulting in a defect that is erroneously detected as a normal battery cell. Summary of the invention

[0010] Technical issues

[0011] To eliminate one or more problems of the related art, embodiments of the present disclosure provide a method of inspecting a battery cell for defects.

[0012] To obviate one or more problems of the related art, embodiments of the present disclosure provide a defect inspection apparatus for a battery cell.

[0013] To eliminate one or more problems of the related art, embodiments of the present disclosure also provide a defect inspection system for a battery cell.

[0014] Technical Solution

[0015] To achieve the purpose of the present disclosure, a method for inspecting a battery cell for defects may include the following steps: calculating a difference between resistance values ​​measured before and after inducing heating of a metal part in the battery cell; and comparing the difference with a predetermined reference value to determine whether a defect occurs in the metal part.

[0016] Calculating the difference between the resistance values ​​may include the steps of: obtaining a first resistance value of the metal portion; inducing heating of the metal portion according to heating conditions; obtaining a second resistance value of the metal portion in which heating is induced; and comparing the first resistance value and the second resistance value to calculate the difference.

[0017] Here, the heating condition may include at least one condition value that ensures that a temperature change of an electrolyte in the battery cell remains below a predetermined reference level.

[0018] In addition, the step of inducing the metal portion to generate heat according to the heat generating condition may include inducing the metal portion to generate heat by charging and discharging the battery cell according to the heat generating condition.

[0019] For example, the heating condition may include at least one of the magnitude of a charge / discharge current for charging and discharging the battery cell, a charge / discharge time, and an external temperature.

[0020] Here, the heating condition may differ according to information on the properties of the battery cells.

[0021] Furthermore, the resistance value may be a value of a real part among impedance values ​​measured at a predefined frequency.

[0022] In addition, comparing the difference with a predetermined reference value to determine whether a defect has occurred in the metal part may include the following steps: when the difference is greater than or equal to the reference value, determining that a defect has occurred in the metal part; and when the difference is less than the reference value, determining that the battery cell is normal.

[0023] According to another embodiment of the present disclosure, a defect inspection device for a battery cell may include: at least one processor; and a memory configured to store at least one instruction executed by the at least one processor, and the at least one instruction may include: instructions for calculating the difference between resistance values ​​measured before and after inducing heating of a metal part in the battery cell; and instructions for comparing the difference with a predetermined reference value to determine whether a defect occurs in the metal part.

[0024] Here, the instructions for calculating the difference between resistance values ​​may include: instructions for obtaining a first resistance value of a metal part; instructions for inducing heating of the metal part according to heating conditions; instructions for obtaining a second resistance value of the metal part that induces heating; and instructions for comparing the first resistance value with the second resistance value to calculate the difference.

[0025] Here, the heating condition may include at least one condition value that ensures that a temperature change of an electrolyte in the battery cell remains below a predetermined reference level.

[0026] In addition, the instruction to induce heating of the metal portion according to the heating condition may include an instruction to induce heating of the metal portion by charging and discharging the battery cell according to the heating condition.

[0027] For example, the heating condition includes at least one of the magnitude of a charge / discharge current for charging and discharging the battery cell, a charge / discharge time, and an external temperature.

[0028] Here, the heating condition may vary according to information on the properties of the battery cells.

[0029] Furthermore, the resistance value may be a value of a real part among impedance values ​​measured at a predefined frequency.

[0030] In addition, the instructions for comparing the difference with a predetermined reference value to determine whether a defect has occurred in the metal part may include: instructions for determining that a defect has occurred in the metal part when the difference is greater than or equal to the reference value; and instructions for determining that the battery cell is normal when the difference is less than the reference value.

[0031] According to another embodiment of the present disclosure, a defect inspection system for a battery cell may include: an impedance measuring device configured to measure a resistance value of a battery cell; a heating device configured to induce heat from a metal portion of the battery cell; and a defect inspection equipment for the battery cell configured to determine whether a defect occurs in the metal portion of the battery cell, wherein the defect inspection equipment for the battery cell is further configured to: calculate a difference between resistance values ​​measured by the impedance measuring device before and after inducing heat in the metal portion; and compare the difference with a preset reference value to check whether a defect occurs in the metal portion.

[0032] Here, the defect inspection equipment for the battery cell can also be configured to: obtain a first resistance value of the metal part from an impedance measuring device before inducing heat in the metal part; send a heating condition to the heating device to induce heating of the metal part; obtain a second resistance value of the metal part in which heating is induced from the impedance measuring device; and compare the first resistance value and the second resistance value to calculate a difference to determine whether a defect occurs in the metal part.

[0033] Here, the heating condition may include at least one condition value that ensures that a temperature change of an electrolyte in the battery cell remains below a predetermined reference level.

[0034] Furthermore, the heat generating device may include a charging / discharging device.

[0035] Furthermore, the resistance value may be a value of a real part among impedance values ​​measured at a predefined frequency.

[0036] Beneficial Effects

[0037] The apparatus and method for inspecting defective battery cells according to the embodiments and experimental examples of the present invention and the system including the same can induce heat in the battery cell to be inspected, and compare the impedance measurement values ​​before and after the heat generation, so that the resistance change of the metal part inside the defective battery cell increases due to the heat generation, thereby providing highly reliable inspection of defects. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a block diagram of a defect inspection system for a battery cell according to an embodiment of the present invention.

[0039] Figure 2 is a block diagram of a processor in a defect inspection apparatus according to an embodiment of the present invention.

[0040] Figure 3 is a flowchart for explaining a method of inspecting a battery cell defect using a defect inspection apparatus according to an embodiment of the present invention.

[0041] Figure 4 is a conceptual diagram of a defect inspection system for inspecting a pouch type battery cell according to an experimental example of the present invention.

[0042] Figure 5 are images of measuring the temperature of a defective battery cell when heat is induced according to an experimental example of the present invention.

[0043] Figure 6 is a graph of impedance measurement results per frequency of a normal battery cell before and after heat generation according to an experimental example of the present invention.

[0044] Figure 7is a graph showing impedance measurement results per frequency of a defective battery cell before and after heating according to another experimental example of the present invention.

[0045] Figure 8 is a table summarizing resistance values ​​of normal battery cells and defective battery cells before and after heat generation according to an experimental example of the present invention.

[0046] 1000: Impedance measurement device 3000: Heating device

[0047] 5000: Defect inspection equipment

[0048] 100: Memory 200: Processor

[0049] 300: transceiver 400: input interface

[0050] 500: output interface 600: storage device

[0051] 700: Bus DETAILED DESCRIPTION

[0052] The present invention can be modified in various forms and has various embodiments, and its specific embodiments are shown by way of example in the accompanying drawings and will be described in detail below. However, it should be understood that it is not intended to limit the present invention to specific embodiments, but rather, the present invention will cover all modifications, equivalents and alternatives that fall within the spirit and technical scope of the present invention. Throughout the description of the drawings, the same reference numerals refer to the same elements.

[0053] It should be understood that, although terms such as first, second, A, B and the like can be used to describe various elements in this article, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, without departing from the scope of the present invention, the first element can be referred to as the second element, and similarly, the second element can be referred to as the first element. As used herein, the term "and / or" includes a combination of any item in a plurality of associated listings or a plurality of associated listings.

[0054] It will be understood that when an element is referred to as being "coupled" or "connected" to another element, it can be directly coupled or connected to the other element, or intervening elements may be present. Conversely, when an element is referred to as being "directly coupled" or "directly connected" to another element, there are no intervening elements.

[0055] The terms used in this application are only used to describe specific embodiments and are not intended to limit the present invention. If there is no obvious opposite meaning in the context, the singular form includes the plural form. In this application, it should be understood that the term "including" or "having" indicates the presence of the features, quantities, steps, operations, components, parts or combinations thereof described in the specification, but does not exclude the possibility of existing or adding one or more other features, quantities, steps, operations, components, parts or combinations thereof in advance.

[0056] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. It will also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and will not be interpreted in an idealized or overly formal sense unless explicitly defined in this article.

[0057] Hereinafter, preferred embodiments according to the present invention will be described in more detail with reference to the accompanying drawings.

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

[0059] Reference Figure 1 , the defect inspection system (S) for a battery cell according to an embodiment of the present invention can induce heating of a battery cell to be inspected and inspect at least one defect occurring in a metal part inside the battery cell.

[0060] More specifically, the defect inspection system for a battery cell may include an impedance measurement device (electrochemical impedance spectroscopy: EIS) 1000 , a heating device 3000 , and a defect inspection apparatus 5000 for a battery cell.

[0061] The impedance measuring device 1000 can measure the resistance value of the battery cell before and after heating.

[0062] As will be described in more detail according to an embodiment, the impedance measuring device 1000 may be respectively connected to an anode and a cathode of a battery cell to be inspected.

[0063] For example, a battery cell may be located on a fixture including a plurality of measuring pins. More specifically, the battery cell may be positioned on the fixture in a state where its positive and negative electrodes are in contact with one end of the plurality of measuring pins, respectively. Therefore, the impedance measuring device 1000 may be connected to the other ends of the plurality of measuring pins, one end of which is in contact with the positive and negative electrodes of the battery cell, respectively. Therefore, 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 fixture may be provided in various forms capable of improving the fixing force according to the shape of the battery cell to be measured, such as a cylindrical, pouch-shaped, or stacked type.

[0064] Thereafter, the impedance measuring device 1000 may apply an AC voltage or an AC current to the battery cell before and after heating. Thus, the impedance measuring device 1000 may measure changes in amplitude and phase of the AC voltage or AC current passing through the battery cell and 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.

[0065] The heating device 3000 may be a device that induces heating of a metal part in a 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 part according to a predefined heating condition. Here, the heating condition may be information about condition settings for minimizing temperature changes of an electrolyte in a battery cell.

[0066] In other words, the defect inspection system for a battery cell according to an embodiment of the present invention can induce heating of a metal part confined within the battery cell, so that the temperature change of the electrolyte in the battery cell can be minimized according to the heating condition. Therefore, the defect inspection system for a battery cell can prevent the occurrence of side reactions caused by the temperature change of the electrolyte when inspecting the battery cell defects.

[0067] In addition, the heating condition may vary depending on the attribute information of the battery cell. For example, the attribute information of the battery cell is an element to determine the battery model and may include the type, the material of the metal part, the number of connectors, etc.

[0068] According to an embodiment, the heating device 3000 may be configured as a charging / discharging device. For example, a charging / discharging device (like the impedance measuring device 1000) may be connected to the other end of a plurality of measuring pins whose one end contacts the positive and negative electrodes of the battery cell. In other words, the charging / discharging device may be electrically connected to the positive and negative electrodes of the battery cell, respectively. Thereafter, the charging / discharging device may charge and discharge the battery cell according to a predefined heating condition. Therefore, the metal part in the battery cell may generate heat. Here, the heating condition may include at least one condition information of the size of the charging / discharging current, the charging / discharging time, and the external temperature to minimize the temperature change of the electrolyte in the battery cell. Here, the size of the charging / discharging current may vary depending on the number and size of the joints as the metal part in the battery cell.

[0069] The heat generating device 3000 is not limited to the disclosed charging / discharging device, and may be applied to various devices capable of inducing heat generation of one or more metal parts within a battery cell.

[0070] The defect inspection apparatus 5000 may be connected to at least one of the impedance measurement device 1000 and the heating device 3000. Therefore, the defect inspection apparatus 5000 may 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 a real part of an impedance value corresponding to a predefined frequency among frequency-specific impedance values ​​measured on the battery cell by the impedance measuring device 1000 before heat generation.

[0072] Additionally, the second resistance value may be a real part of an impedance value corresponding to a predefined frequency among frequency-specific impedance values ​​measured by the impedance measuring device 1000 after heat is generated in the battery cell.

[0073] Here, the predefined frequency may be defined as a specific frequency 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 above the reference frequency 600 Hz.

[0074] Thereafter, the defect inspection device 5000 may compare the first resistance value and the second resistance value to determine whether a defect occurs in a metal part within the battery cell. Here, the metal part may include at least one of a joint and a lead inside the battery cell. Additionally, the defect in the metal part may include at least one of a welding defect between joints, a welding defect between a joint and a lead, and a disconnection of a joint.

[0075] In the case of metal, as the temperature increases, the number of collisions of electrons increases, the frequency of atoms increases, and the resistance value may increase. Here, according to one embodiment, when a welding defect (such as a welding defect between joints or a welding defect between a joint and a lead) or a complete disconnection (such as a joint disconnection) occurs in the metal part, this causes contact resistance between the joints or between the joint and the lead, and the resistance value may increase by a larger amount (about 1% to 3% in the case of disconnection) compared to a normal battery cell. Therefore, the defect inspection equipment 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, and amplify the tiny resistance values ​​in weak welds and joint disconnections that are difficult to detect, thereby enabling stable inspection of these defects.

[0076] In addition, the defect inspection device 5000 may include a heating condition according to the property information of the battery cell. Therefore, when inducing heat in the metal part within the battery cell, the defect inspection device 5000 may send the heating condition corresponding to the property information of the battery cell to the heating device 3000. Therefore, the heating device 3000 may generate heat in the metal part of the battery cell under a predetermined condition value that minimizes the temperature change of the electrolyte in the battery cell.

[0077] Figure 2 is a block diagram of a processor in a defect inspection apparatus according to an embodiment of the present invention.

[0078] Reference Figure 2 , the defect inspection apparatus 5000 may include a memory 100 , a processor 200 , a transceiver 300 , an input interface 400 , an output interface 500 , and a storage device 600 .

[0079] According to an embodiment, the respective components 100 , 200 , 300 , 400 , 500 , 600 included in the defect inspection apparatus 5000 may be connected through a bus 700 to communicate with each other.

[0080] The memory 100 and the storage device 600 among the components 100, 200, 300, 400, 500, 600 of the defect inspection apparatus 5000 may include 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 include at least one of a read-only memory (ROM) and a random access memory (RAM).

[0081] The memory 100 may include at least one instruction executed by the processor 200 .

[0082] According to an embodiment, at least one instruction may include: an instruction for calculating a difference between resistance values ​​measured before and after inducing heating of the metal part in the battery cell; and an instruction for comparing the difference with a predetermined reference value to determine whether a defect occurs in the metal part.

[0083] Here, the instructions for calculating the difference between the resistance values ​​may include: instructions for obtaining a first resistance value of the metal part; instructions for inducing heating of the metal part according to heating conditions; instructions for obtaining a second resistance value of the metal part that induces heating; and instructions for comparing the first resistance value and the second resistance value to calculate the difference.

[0084] Here, the heating condition may include at least one condition value that ensures that a temperature change of an electrolyte in the battery cell remains below a predetermined reference level.

[0085] In addition, the instruction to induce heating of the metal portion according to the heating condition may include an instruction to induce heating of the metal portion by charging and discharging the battery cell according to the heating condition.

[0086] For example, the heating condition includes at least one of the magnitude of a charge / discharge current for charging and discharging the battery cell, a charge / discharge time, and an external temperature.

[0087] Here, the heating condition may vary according to information on the properties of the battery cells.

[0088] Furthermore, the resistance value may be a value of a real part among impedance values ​​measured at a predefined frequency.

[0089] In addition, the instructions for comparing the difference with a predetermined reference value to determine whether a defect has occurred in the metal part include: instructions for determining that a defect has occurred in the metal part when the difference is greater than or equal to the reference value; and instructions for determining that the battery cell is normal when the difference is less than the reference value.

[0090] Furthermore, the processor 200 may represent a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which the method according to the embodiment of the present invention is executed.

[0091] As described above, the processor 200 may execute at least one program command stored in the memory 100 .

[0092] Figure 3 is a flowchart for explaining a method of inspecting a battery cell defect using a defect inspection apparatus according to an embodiment of the present invention.

[0093] Reference Figure 3, the processor 200 in the defect inspection apparatus 5000 may obtain a first resistance value measured from a battery cell as an inspection target (S1000). Here, the battery cell may be a battery cell that does not induce heat generation of a metal portion.

[0094] In addition, the first resistance value may be a real part of an impedance value corresponding to a predefined frequency. Here, the predefined frequency may be defined as a specific frequency 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 above a reference frequency of 600 Hz.

[0095] According to an embodiment, the processor 200 may receive an impedance value for each frequency from the impedance measuring device 1000 through the transceiver 300. Thereafter, the processor 200 may obtain a first resistance value by obtaining a real part of the impedance measured at a predefined frequency among the received impedance values.

[0096] According to another embodiment, the processor 200 may receive and obtain a first resistance value from the impedance measuring device 1000 through the transceiver 300 , where the first resistance value is a real part of an impedance value corresponding to a predefined frequency.

[0097] Thereafter, the processor 200 may operate the heating device 3000 to induce heating of the metal portion within the battery cell ( S3000 ).

[0098] According to an embodiment, the processor 200 may send at least one heating condition and an operation signal to the heating device 3000 using the transceiver 300. Here, the heating condition may be a predefined condition value to minimize the temperature change of the electrolyte in the battery cell. According to an embodiment, when the heating device 3000 is a charging / discharging device, the heating condition may include at least one of the size of the charging / discharging current, the charging / discharging time, and the external temperature that are predefined to minimize the temperature change of the electrolyte in the battery cell.

[0099] For example, according to the property information of the battery cell, the heating condition may be pre-stored in the memory 100 in the form of a table of at least one condition value. Therefore, the processor 200 may obtain the heating condition corresponding to the property information of the battery cell as the inspection target, and send the heating condition to the heating device 3000.

[0100] Thereafter, the processor 200 may obtain a second resistance value measured from the heating battery cell (S5000). In other words, the battery cell may be in a state where the heating device 3000 intentionally induces heating of a metal portion within the battery cell.

[0101] The second resistance value may be real part information of the impedance value corresponding to the predefined frequency. Here, the predefined frequency may be defined as a specific frequency higher than the predefined reference frequency. For example, the specific frequency may be 850 Hz, which is one of the frequencies in the high frequency range above the reference frequency of 600 Hz.

[0102] According to one embodiment, the processor 200 may receive a frequency-specific impedance value of a battery cell where a metal part generates heat measured by the impedance measuring device 1000 through the transceiver 300. Thereafter, the processor 200 may obtain a second resistance value by obtaining a real part of the impedance measured at a predefined frequency among the received impedance values.

[0103] According to another embodiment, the processor 200 may receive a second resistance value which is a real part of an impedance value corresponding to a predefined frequency among frequency-specific impedance values ​​of the battery cell in which the metal part generates heat, from the impedance measuring device 1000 through the transceiver 300 .

[0104] Thereafter, the processor 200 may compare the first resistance value and the second resistance value to determine whether the metal portion within the battery cell is defective ( S7000 ).

[0105] In more detail, the processor 200 may calculate a difference between the first resistance value and the second resistance value. Thereafter, the processor 200 may compare the difference with a predefined reference value. Here, the reference value may vary depending on the number and size of the joints that may serve as the metal part in the battery cell. For example, the reference value may be 0.007 mΩ.

[0106] According to one embodiment, when the difference is greater than or equal to the reference value, the processor 200 may determine that a defect has occurred in the metal part of the battery cell.

[0107] According to another embodiment, when the difference is less than the reference value, the processor 200 may determine that there is no abnormality in the metal portion of the battery cell.

[0108] Method for inspecting defective battery cells according to experimental example of the present invention

[0109] Figure 4 is a conceptual diagram of a defect inspection system for inspecting a pouch type battery cell according to an experimental example of the present invention.

[0110] like Figure 4 As shown, normal cells and defective battery cells of the same model including 20 joints are prepared and provided in the form of a bag. Here, the defective battery cell is a battery cell having a 35 mm break in the joint.

[0111] First, a normal battery cell is fixed to a clamp-shaped fixture. Then, an AC voltage is applied to both terminals of the electrodes of the normal battery cell using the impedance measuring device 1000. Thereafter, while changing the frequency from 1Khz to 400hz, the impedance value at a predetermined reference frequency is first measured before heat generation.

[0112] Thereafter, a heating condition corresponding to the property information of the normal battery cells is determined using the charging / discharging device as the heating device 3000 .

[0113] According to the heating condition, the external temperature was set to 22° C., and charging and discharging were performed by applying a charging current and a discharging current of 60 A for 5 seconds, respectively.

[0114] Thereafter, the impedance value of the normal battery cell at the predefined reference frequency is measured again for a second time using the impedance measuring device 1000 .

[0115] Thereafter, under the same conditions as the normal battery cells, the impedance values ​​of the defective battery cells at the predefined reference frequency are measured before and after heating, respectively.

[0116] Thereafter, using the defect inspection apparatus 5000 , defects in the metal parts of the normal battery cells and the defective battery cells are respectively inspected.

[0117] Figure 5 are images of measuring the temperature of a defective battery cell when heat is induced according to an experimental example of the present invention.

[0118] Reference Figure 5 As a result of measuring the temperature of the entire metal joint after charging and discharging of the normal battery cell, 25.038° C. was obtained as an average temperature, and as a result of measuring the temperature of the entire joint after charging and discharging of the defective battery cell, 26.393° C. was obtained as an average temperature. In other words, it can be understood that the average temperature of the defective battery cell after charging and discharging is 1.355° C. higher than the average temperature of the normal battery cell after charging and discharging.

[0119] Figure 6 is a graph of impedance measurement results per frequency of a normal battery cell before and after heat generation according to an experimental example of the present invention. Figure 7 is a graph showing impedance measurement results per frequency of a defective battery cell before and after heating according to another experimental example of the present invention. Figure 8 is a table summarizing resistance values ​​of normal battery cells and defective battery cells before and after heat generation according to an experimental example of the present invention.

[0120] exist Figures 6 to 8, according to the impedance measurement curve graphs at each frequency of the normal battery cell and the defective battery cell, in the high frequency region above the reference frequency (fs), obvious differences are shown in the real part values ​​of the impedance before charging / discharging and the real part values ​​of the impedance after charging / discharging.

[0121] Therefore, based on the value of the real part of the impedance of the normal battery cell at the predefined frequency and the value of the real part of the impedance of the defective battery cell at the predefined frequency, the difference before and after the heat is induced using the charging and discharging device is studied. The real part of the impedance of the normal battery cell before charging / discharging is 0.862mΩ, and the real part of the impedance of the defective battery cell before charging / discharging is 0.866mΩ. In other words, it can be understood that the real part of the impedance of the defective battery cell before charging / discharging is 0.004mΩ greater than the real part of the impedance of the normal battery cell before charging / discharging.

[0122] In addition, the real part of the impedance of the normal battery cell after charging / discharging is 0.871 mΩ, and the real part of the impedance of the defective battery cell after charging / discharging is 0.881 mΩ, from which it can be understood that the real part of the impedance of the defective battery cell after charging / discharging is 0.01 mΩ larger than that of the normal battery cell.

[0123] In addition, the increase in the real part of the impedance of the normal battery cell before and after charging and discharging is 0.009 mΩ, while the increase in the real part of the impedance of the defective battery cell before and after charging and discharging is 0.015 mΩ, which means that the increase in the real part of the impedance of the defective battery cell is 0.006 mΩ greater than the increase in the real part of the impedance of the normal battery cell.

[0124] Therefore, as a result of comparing the impedance difference between the normal battery cell and the defective battery cell, it can be understood that the difference (0.01 mΩ) between the normal battery cell and the defective battery cell in the real part of the impedance measured after inducing heat in the metal portion by charging / discharging increases by 2.5 times, compared to the difference (0.004 mΩ) between the normal battery cell and the defective battery cell in the real part of the impedance measured without inducing heating of the metal portion. In addition, the difference (0.006 mΩ) between the change in the real part of the impedance before and after charging / discharging of the normal battery cell and the change in the real part of the impedance before and after charging / discharging of the defective battery cell is shown as 1.5 times the difference (0.004 mΩ) in the change in the real part of the impedance measured without inducing any heat.

[0125] In summary, it can be understood that the impedance difference between the normal battery cell and the defective battery cell shows the maximum difference in the real part value of the impedance measured at the reference frequency range after inducing heating of the metal portion.

[0126] Therefore, the method for inspecting defective battery cells according to the experimental example of the present invention can intentionally induce heat generation in the metal part of the battery cell, and determine whether the metal part of the battery cell is defective based on the change in the real part of the impedance before and after the heat generation, thereby being able to inspect defects in the metal part with high precision.

[0127] The apparatus and method for inspecting defective battery cells according to the embodiments and experimental examples of the present invention, and the system including the apparatus have been described.

[0128] According to the embodiments and experimental examples of the present invention, an apparatus and method for inspecting defective battery cells and a system including the apparatus can induce heat in a metal part of a battery cell using a heating device, and determine whether the metal part of the battery cell is defective based on the amount of change in impedance before and after the heat generation, and thereby improve the inspection capability even for micro defects such as weak welding or disconnection of a joint part by increasing the resistance value of the defective metal part due to heat generation.

[0129] The operation of the method according to the embodiment of the present invention and the experimental example can be implemented as a computer-readable program or code on a computer-readable recording medium. The computer-readable recording medium includes all types of recording devices in which data readable by a computer system is stored. In addition, the computer-readable recording medium can be distributed in a network-connected computer system to store and execute the computer-readable program or code in a distributed manner.

[0130] In addition, the computer readable recording medium may include hardware devices such as ROM, RAM, flash memory, etc. that are specifically configured to store and execute program instructions. The program instructions may include not only machine language codes created by a compiler, but also high-level language codes that can be executed by a computer using an interpreter.

[0131] Although some aspects of the present invention have been described in the context of an apparatus, it may also be represented by a description according to a corresponding method, wherein a box or apparatus corresponds to a method step or a feature of a method step. Similarly, the aspects described in the context of a method may also represent features of a corresponding box or project or a corresponding apparatus. 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 important method steps may be performed by such an apparatus.

[0132] Hereinabove, the present invention has been described with reference to exemplary embodiments thereof, but those skilled in the art will appreciate that various corrections and changes may be made to the present invention within the scope without departing from the spirit and scope of the invention described in the appended claims.

Claims

1. A method for inspecting battery cell defects, the method comprising the following steps: The difference between the resistance values ​​measured before and after inducing heating of the metal part is calculated for the battery cell object; as well as The difference is compared with a predetermined reference value to determine whether a defect occurs in the metal portion.

2. The method according to claim 1, wherein: The step of calculating the difference between the resistance values ​​comprises the following steps: obtaining a first resistance value of the metal portion; inducing the metal portion to generate heat according to a heating condition; obtaining a second resistance value of the metal portion that induces heat generation; and The first resistance value and the second resistance value are compared to calculate the difference value.

3. The method according to claim 1, wherein: The heating condition includes at least one condition value that ensures that a temperature change of an electrolyte in the battery cell remains below a predetermined reference level.

4. The method according to claim 2, wherein: The step of inducing the metal portion to generate heat according to the heating condition includes inducing the metal portion to generate heat by charging and discharging the battery cell according to the heating condition.

5. The method according to claim 4, wherein: The heating condition includes at least one of a magnitude of a charge and discharge current for charging and discharging the battery cell, a charge and discharge time, and an external temperature.

6. The method according to claim 3, wherein: The heat generation condition differs according to information about the property of the battery cell.

7. The method according to claim 1, wherein: The resistance value is a value of a real part of an impedance value measured at a predefined frequency.

8. The method according to claim 1, wherein: The step of determining whether a defect occurs in the metal part comprises the following steps: when the difference is greater than or equal to the reference value, determining that a defect has occurred in the metal portion; and When the difference is less than the reference value, it is determined that the battery cell is normal.

9. A battery cell defect inspection device, the device comprising: Memory; as well as a processor that executes at least one instruction stored in the memory, The at least one instruction includes: An instruction for calculating, for a battery cell, a difference between resistance values ​​measured before and after heating of the metal portion is induced; and Instructions for comparing the difference with a predetermined reference value to determine whether a defect occurs in the metal portion.

10. The device according to claim 9, wherein: The instructions for calculating the difference between the resistance values ​​include: an instruction for obtaining a first resistance value of the metal portion; an instruction for inducing heating of the metal portion according to a heating condition; instructions for obtaining a second resistance value of the metal portion that induces the heat generation; and Instructions for comparing the first resistance value to the second resistance value to calculate the difference.

11. The device according to claim 9, wherein: The heating condition includes at least one condition value that ensures that a temperature change of an electrolyte in the battery cell remains below a predetermined reference level.

12. The device according to claim 10, wherein: The instructions to induce heating of the metal portion according to the heating condition include instructions to induce heating of the metal portion by charging and discharging the battery cell according to the heating condition.

13. The device according to claim 12, wherein: The heating condition includes at least one of a magnitude of a charge and discharge current for charging and discharging the battery cell, a charge and discharge time, and an external temperature.

14. The device according to claim 11, wherein: The heat generation condition differs according to information about the property of the battery cell.

15. The apparatus according to claim 9, wherein: The resistance value is a value of a real part of an impedance value measured at a predefined frequency.

16. The apparatus according to claim 9, wherein: The instructions for determining whether a defect occurs in the metal portion include: instructions for determining that a defect has occurred in the metal portion when the difference is greater than or equal to the reference value; and An instruction for determining that the battery cell is normal when the difference is less than the reference value.

17. A battery cell defect inspection system, the system comprising: an impedance measuring device, the impedance measuring device being configured to measure the resistance value of the battery cell; a heat generating device configured to induce heat generation from a metal portion of the battery cell; as well as a defect inspection device for a battery cell, the defect inspection device for a battery cell being configured to determine whether a defect occurs in the metal portion of the battery cell, Wherein, the battery cell defect inspection device is further configured as follows: calculating a difference between resistance values ​​measured by the impedance measuring device before and after inducing heating of the metal portion; as well as The difference is compared with a preset reference value to check whether a defect occurs in the metal part.

18. The system of claim 17, wherein: The battery cell defect inspection device is further configured as follows: obtaining a first resistance value of the metal portion from the impedance measuring device before inducing the metal portion to generate heat; sending a heating condition to the heating device to induce heating of the metal part; obtaining a second resistance value of the metal portion that induces heat generation from the impedance measuring device; as well as The first resistance value and the second resistance value are compared to calculate the difference, thereby determining whether a defect occurs in the metal portion.

19. The system of claim 18, wherein: The heating condition includes at least one condition value that ensures that a temperature change of an electrolyte in the battery cell remains below a predetermined reference level.

20. The system of claim 17, wherein: The heating device includes a charging and discharging device.

21. The system of claim 17, wherein: The resistance value is a value of a real part of an impedance value measured at a predefined frequency.

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