Apparatus for inspecting electrode assembly for defects before electrolyte injection and method for inspecting defects thereof

Abstract

The device for checking a failure of an electrode assembly before injection of an electrolyte of the present technology includes a short circuit tester configured to detect a short circuit of the electrode assembly by applying a predetermined voltage to a positive electrode and a negative electrode of the electrode assembly; a multimeter electrically connected to the short circuit tester and configured to measure a voltage and a current of the electrode assembly over time; and a failure determination part connected to the multimeter and configured to monitor a change in the voltage and the current measured by the multimeter, and to determine a failure type of the electrode assembly according to data on a change in the voltage and the current over a predetermined period of time. The method of checking a failure of an electrode assembly before injection of an electrolyte of the present technology includes measuring a voltage and a current of the electrode assembly over time by applying a predetermined voltage to a positive electrode and a negative electrode of the electrode assembly; and determining at least one failure type from among a false failure, a bridge failure, and a point failure according to data on a change in the voltage and the current over a predetermined period of time.

Description

TECHNICAL FIELD

[0001] The present application relates to an apparatus and method for inspecting a failure of an electrode assembly. More particularly, the present application relates to an apparatus and method for inspecting a failure of an electrode assembly capable of determining a failure type of the electrode assembly before an electrolyte is injected into the electrode assembly.

[0002] This application claims priority from Korean Patent Application No. 10-2021-0018508 filed on February 9, 2021, and the entire contents of which are incorporated herein by reference. BACKGROUND

[0003] With the technical development and increasing demand for mobile devices, the demand for secondary batteries is also rapidly increasing. Among the secondary batteries, lithium secondary batteries are widely used as energy sources for various electronic products and various mobile devices because of their high energy density and high operating voltage as well as good storage and lifespan characteristics.

[0004] An electrode assembly having a structure composed of a positive electrode, a separator, and a negative electrode to form a lithium secondary battery is mainly classified into a jelly-roll type (winding type), a stacking type (accumulation type), and a stacking / folding type, which is a type of combination of the jelly-roll type and the stacking type, according to its structure. The manufacturing method of the electrode assembly is slightly changed according to the above structure.

[0005] The electrode assembly is accommodated in a case, and the secondary battery can be classified into a prismatic type, a coin type, a cylindrical type, a pouch type, etc. according to the shape of the case. Next, a process of injecting an electrolyte into the case is performed. That is, the lithium secondary battery is manufactured by injecting the electrolyte in a state in which the electrode assembly is accommodated in the battery case and then sealing the case.

[0006] Meanwhile, the electrode assembly is subjected to a failure inspection process and then accommodated in an external material by being filled with an electrolyte and being sealed. As a method of inspecting a failure before the electrolyte is injected, a short circuit inspection for detecting a short circuit state of the electrode assembly is performed. Before the electrolyte is injected, the positive electrode and the negative electrode of the electrode assembly are electrically insulated by the separator between the positive electrode and the negative electrode. However, in the manufacturing process, for some reasons, the insulation can be damaged and a short circuit in which the positive electrode and the negative electrode are electrically connected can occur. Since the failure electrode assembly in which the short circuit has occurred reduces the manufacturing yield, the failure electrode assembly is detected by a short circuit tester and excluded from the production line.

[0007] Figure 1 FIG. 1 is a schematic view showing a configuration of a conventional short circuit tester 20.

[0008] In Figure 1In the meantime, the electrode assembly 10 is accommodated in the case 4, and an electrolyte is not injected into the case 4. The electrode assembly 10 is composed of the positive electrode 1, the separator 2, and the negative electrode 3, and the short-circuit tester 20 is electrically connected with the tabs (terminals) la and 3a of the positive electrode 1 and the negative electrode 3. The short-circuit tester is provided with a predetermined power source, and a predetermined voltage is applied from the power source to the electrode assembly 10 to detect a short-circuit state of the electrode assembly.

[0009] However, the conventional short-circuit tester detects only a magnitude of a voltage or a current of the electrode assembly 10 detected by applying a constant voltage to the electrode assembly 10 at a specific point of time, and compares a value of the magnitude with a set value to determine whether the electrode assembly 10 is PASS or FAIL. For example, when a current value is lower than the set value, "PASS" is displayed on the display panel 21 of the short-circuit tester 20, and when an overcurrent higher than the set value flows, "FAIL" is displayed on the display panel 21 of the short-circuit tester 20. However, although the conventional short-circuit tester 20 can find a failure, the conventional short-circuit tester 20 can not specifically identify a cause of the failure. To prevent a recurrence of the failure, the cause of the failure should be identified and removed. In addition, for research and development of the electrode assembly, a type of the failure needs to be clarified.

[0010] In particular, it is difficult to detect an error failure of a non-actual product failure caused by a circuit disconnection, a pin contact abnormality, etc. using the conventional short-circuit tester. When a normal electrode assembly is determined as a failure due to equipment abnormality, this becomes a factor of reducing a manufacturing yield. Alternatively, when an abnormal electrode assembly is determined as normal due to equipment abnormality, this results in the same result due to no actual inspection of the electrode assembly, resulting in a reduction in inspection accuracy.

[0011] In addition, there are several types of inherent failures in which a current exceeds a measurement upper limit due to occurrence of a short circuit and is determined as a High Fail by the short-circuit tester. For example, it is difficult for the conventional short-circuit tester to distinguish between a bridge failure in which a separation occurs in an electrode and the separated part connects a positive electrode and a negative electrode like a bridge to generate a short circuit, or a spot failure in which a spot hole is generated in a separator, and thus insulation between the positive electrode and the negative electrode is damaged.

[0012] In order to detect the above-described types of failures, a specific analysis of a change in a voltage or a current of the electrode assembly is required, but the conventional short-circuit tester calculates only a magnitude of a voltage or a current of the electrode assembly at a specific point of time to determine only PASS / FAIL, and it is difficult to measure a change in the voltage or the current with time.

[0013] Therefore, there is a need to develop a failure inspection technique capable of inspecting a short circuit or a cause of a failure of an electrode assembly before an electrolyte is injected into a secondary battery.

[0014]

PRIOR ART DOCUMENTS

[0015]

PATENT DOCUMENTS

[0016] Korean Patent Publication No. 10-1775213 SUMMARY

[0017]

DISCLOSURE

[0018]

PROBLEM TO BE SOLVED BY THE INVENTION

[0019] An object of the present invention is to provide an apparatus for inspecting a failure of an electrode assembly capable of effectively determining a failure type of the electrode assembly before an electrolyte is injected.

[0020] Another object of the present invention is to provide a method of inspecting a failure of an electrode assembly capable of detecting an error failure, a bridge failure, and a point failure that can not be determined by a conventional short circuit tester.

[0021]

TECHNICAL SOLUTION

[0022] One aspect of the present invention provides an apparatus for inspecting a failure of an electrode assembly before an electrolyte is injected, including a short circuit tester configured to detect a short circuit of the electrode assembly by applying a predetermined voltage to a positive electrode and a negative electrode of the electrode assembly; a multimeter electrically connected to the short circuit tester and configured to measure a voltage and a current of the electrode assembly over time; and a failure determination part connected to the multimeter and configured to monitor a change in the voltage and the current measured by the multimeter, and to determine a type of the failure of the electrode assembly according to data on the change in the voltage and the current over a predetermined period of time.

[0023] In an example, the multimeter can be a digital multimeter.

[0024] In a preferred example, the failure determination part can be connected to the short circuit tester and can receive information on the short circuit detection from the short circuit tester.

[0025] In an example, the failure determination part can detect the electrode assembly having an error failure by comparing the voltage waveform and the current waveform.

[0026] In particular, when a peak value is not present in the current waveform when the voltage waveform is a normal waveform, the failure determination part can determine the failure as an error failure.

[0027] In another example, when the peak value of the current waveform determined according to a type of the electrode assembly when the voltage waveform is a normal waveform is less than or equal to a predetermined size, the failure determination part can determine the failure as an error failure.

[0028] In another embodiment, the fault determining part can detect the electrode assembly having the bridge fault and the point fault according to data on variations in voltage and current of the electrode assembly having a fault determined as high by the short circuit tester for a predetermined period of time.

[0029] In a certain example, the fault determining part can determine the electrode assembly having a maximum voltage lower than a threshold maximum voltage, which is a maximum voltage at a point at which maximum voltage statistical distribution curves of the electrode assembly having the bridge fault and the electrode assembly having the point fault first overlap each other, as having the bridge fault.

[0030] Further, the fault determining part can determine the electrode assembly having a maximum voltage greater than a threshold maximum voltage, which is a maximum voltage at a point at which maximum voltage statistical distribution curves of the electrode assembly having the bridge fault and the electrode assembly having the point fault first overlap each other, as having the point fault.

[0031] Another aspect of the present application provides a method of inspecting a fault of an electrode assembly before injecting an electrolyte, including measuring voltage and current of the electrode assembly over time by applying a predetermined voltage to a positive electrode and a negative electrode of the electrode assembly; and determining at least one fault type from among a false fault, a bridge fault, and a point fault according to data on variations in the voltage and the current for a predetermined period of time.

[0032] In a certain example, in the fault inspection method, when a peak value is not present in a current waveform at a time when a voltage waveform of the electrode assembly is a normal waveform, it can be determined as the false fault.

[0033] As another example, in the fault inspection method, when a peak value of the current waveform determined according to a type of the electrode assembly is less than or equal to a predetermined size at a time when the voltage waveform of the electrode assembly is the normal waveform, it can be determined as the false fault.

[0034] In another embodiment, in the electrode assembly fault inspection method, when a maximum current value measured by the electrode assembly exceeds a set upper limit value, the electrode assembly having the bridge fault and the point fault can be detected according to data on variations in voltage of the electrode assembly for a predetermined period of time.

[0035] In a certain example, the electrode assembly having a maximum voltage lower than a threshold maximum voltage, which is a maximum voltage at a point at which maximum voltage statistical distribution curves of the electrode assembly having the bridge fault and the electrode assembly having the point fault first overlap each other, can be determined as having the bridge fault, and the electrode assembly having a maximum voltage greater than the threshold maximum voltage can be determined as having the point fault.

[0036]

Advantageous Effects

[0037] According to the present application, an error failure of an electrode assembly before an electrolyte is injected can be accurately determined, thereby improving manufacturing yield.

[0038] Further, according to the present application, a cause of failure can be effectively specified by identifying a type of inherent failure such as a bridge failure and a point failure. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 is a schematic diagram showing a configuration of a conventional short circuit tester.

[0040] Figure 2 is a schematic diagram showing a configuration of an electrode assembly failure inspection device of the present application.

[0041] Figure 3 is a graph showing a PASS / FAIL determination result of the short circuit tester of Figure 2

[0042] Figure 4 is a voltage and current waveform graph of a normal electrode assembly.

[0043] Figure 5 is a set of graphs showing a comparison between voltage current waveforms of each of a normal electrode assembly and an error failure electrode assembly measured by the electrode assembly failure inspection device of the present application.

[0044] Figure 6 is a set of graphs showing maximum voltages of bridge failures and point failures according to a frequency of each failure.

[0045] Figure 7 is a graph showing maximum voltages of bridge failures and point failures according to a frequency of each failure of another embodiment. DETAILED DESCRIPTION

[0046] Hereinafter, a detailed configuration of the present application will be described in detail with reference to the accompanying drawings and various embodiments. The embodiments described below are exemplarily shown in order to understand the present application, and the accompanying drawings are not shown in actual scale in order to help understanding of the present application, and the size of some components can be exaggerated.

[0047] While the present application is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the application to the particular forms disclosed, but on the contrary, the application is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the application.

[0048] ​The electrode assembly fault inspection device of the present invention is used for an electrode assembly before electrolyte injection. The electrode assembly before electrolyte injection includes all of the following: an electrode monomer assembly in which the positive electrode, separator, and negative electrode are laminated through a lamination process and cut into monomer units, a stacked electrode assembly in which the electrode monomer assemblies are stacked, a folded electrode assembly in which the electrode monomer assemblies are folded with separators, a stacked-folded electrode assembly in which the electrode monomer assemblies are stacked and folded with separators, and a packaged monomer in which the electrode monomer assembly is housed in a housing but is still in the stage before the electrolyte is injected. Therefore, the electrode assembly to be inspected of the present invention does not have to be housed in a housing.

[0049] Figure 2 : is a schematic diagram showing the configuration of the electrode assembly failure inspection device of the present invention.

[0050] The electrode assembly fault inspection device 100 of the present invention includes: a short circuit tester 20, which is configured to detect a short circuit of the electrode assembly 10 by applying a predetermined voltage to the positive electrode 1 and the negative electrode 3 of the electrode assembly 10; a multimeter 30, which is electrically connected to the short circuit tester 20 and is configured to measure the voltage and current of the electrode assembly 10 over time; and a fault determination part 40, which is connected to the multimeter 30 and is configured to monitor changes in the voltage and current measured by the multimeter, and determine the type of fault of the electrode assembly 10 based on data about the changes in voltage and current within a predetermined time period.

[0051] For ease of description, Figure 2 In the inspection apparatus 100 , the size of the electrode assembly 10 or the battery cell is exaggerated to be larger than the sizes of the short-circuit tester 20 , the multimeter 30 , and the fault determination part 40 .

[0052] The present invention includes a short circuit tester 20 configured to apply a predetermined voltage to the electrode assembly 10, which is housed in the case 4 or not housed in the case 4, before injecting the electrolyte. The short circuit tester 20 is provided with a predetermined power source, and thus detects a short circuit state of the electrode assembly 10 by applying a predetermined voltage from the power source to the positive electrode 1 and the negative electrode 3 of the electrode assembly 10. The short circuit tester 20 determines whether the electrode assembly is passed or failed by applying a predetermined voltage set according to the type or size of the electrode assembly 10 and measuring the current / voltage generated from the electrode assembly due to the application of the voltage and measured from the electrode assembly.

[0053] Figure 3 It shows Figure 2 A diagram showing the results of the PASS / FAIL determination of a short circuit tester.

[0054] like Figure 3As shown, 36 High Fails detected by the short circuit tester 20 are shown as an example of the fault type. The term "High Fail" refers to a fault in which a short circuit is generated in the electrode assembly 10 and the current value exceeds the measurement limit or the set current upper limit of the short circuit tester 20. However, the short circuit tester 20 can only determine pass / fail of the electrode assembly and can not identify a specific type of fault. This is because the short circuit tester 20 is set to determine pass / fail using the current or voltage value measured at a specific point in time, and even when the current / voltage value at different points in time can be measured, the corresponding digital data measured by the short circuit tester 20 is volatile without being saved due to the characteristics of the device. Therefore, it is difficult for the short circuit tester 20 to determine a specific type of fault, particularly an error fault such as a pin contact fault.

[0055] The inspection device 100 of the present application includes a multimeter 30 electrically connected to the short circuit tester 20 to measure the voltage and current of the electrode assembly 10 over time. Since the multimeter 30 is not provided with a power source, the multimeter 30 can not independently apply a voltage to the electrode assembly 10. However, when the multimeter 30 is electrically connected to the terminals of the short circuit tester 20, the multimeter 30 is in a form of being electrically connected to the electrode assembly 10 through the short circuit tester 20. Therefore, the voltage and current values that are volatile without being saved due to the short circuit tester 20 can also be continuously measured by the multimeter 30. The multimeter 30 can include a digital multimeter (DMM) capable of easily measuring voltage, current, resistance, etc.

[0056] The fault inspection device 100 of the present application further includes a fault determination part 40 connected to the multimeter 30 and configured to monitor the changes in voltage and current measured by the multimeter 30 and determine the type of fault of the electrode assembly 10 according to data on the changes in voltage and current over a predetermined period of time. The fault determination part 40 can monitor the changes in voltage and current values measured by the multimeter 30 over time and visually display the changes thereof in a graph or waveform. To this end, the fault determination part 40 includes a storage part configured to store voltage and current data received from the multimeter; a conversion part configured to convert the changes in data over time into visual information in a graph or waveform; and a determination part configured to determine the type of fault of the electrode assembly according to data on the changes in voltage and current over a predetermined period of time. For data conversion or fault determination, the fault determination part 40 is provided with predetermined software (LAP VIEW). In addition, the inspection device 100 of the present application can include a display part 50 configured to display visual information on the changes in voltage and current data over time in the form of a graph or waveform.

[0057] As described above, in the present application, the voltage and current values over time that are difficult to measure using a conventional short circuit tester can be measured by connecting the multimeter 30 to the short circuit tester 20, and the changes in voltage and current of the electrode assembly 10 can be continuously monitored by connecting the multimeter 30 to the fault determination part 40 equipped with a specific development software. In the present application, an inexpensive multimeter commonly used in the field of electrical engineering is provided as a part of the inspection device, and the fault determination part of the predetermined software determines the type of fault, so that the fault of the electrode assembly 10 can be inspected at a low cost without using an expensive tester such as an oscilloscope or a pulse tester.

[0058] The fault determination part 40 of the present application can determine the type of fault not only considering the change in voltage over a predetermined period of time but also considering the change in current over a predetermined period of time. The application time (e.g., several hundreds to several thousands of milliseconds) with which the voltage and current changes that can determine the fault can be different depending on the type of fault, the type and size of the electrode assembly 10 or the battery cell employing the same, etc.

[0059] The electrode assembly fault inspection method of the present application before the injection of an electrolyte includes measuring the voltage and current of an electrode assembly over time by applying a predetermined voltage to a positive electrode and a negative electrode of the electrode assembly, and determining a fault of at least one fault type from among a false fault, a bridge fault, and a point fault, according to data on the change in voltage and current over a predetermined period of time.

[0060] According to the inspection method of the present application, first, a predetermined voltage is applied to a positive electrode and a negative electrode of an electrode assembly to measure the voltage and current of the electrode assembly over time. The application of the voltage can be performed by a short circuit tester 20 as shown in FIG. 1. In addition, the measurement of the voltage and current of the electrode assembly over time can be performed by a digital multimeter connected to the short circuit tester. As described above, by connecting only the digital multimeter to the conventional short circuit tester, the changes in voltage and current of the electrode assembly over time can be measured without adding a separate power source or device. Figure 2

[0061] Next, the inspection method of the present application includes determining at least one fault type from among a false fault, a bridge fault, and a point fault, according to data on the change in voltage and current over a predetermined period of time. In the present application, the type of fault is determined by considering both the data of voltage and current, not the data of either one of voltage or current.

[0062] Hereinafter, the electrode assembly fault inspection process according to the present application will be described in more detail.

[0063]

Mode of the Invention

[0064] (First Embodiment) ​

[0065] First, a case of an electrode assembly having an error failure detected according to the present application will be described.

[0066] According to the present application, an electrode assembly having an error failure can be detected by comparing voltage and current waveforms. The voltage and current waveforms of a normal electrode assembly will be first described in order to identify the waveform in an error failure.

[0067] Figure 4 is a graph of the voltage and current waveforms of a normal electrode assembly for a predetermined period of time (2200 msec). The voltage and current waveforms are prepared based on data measured by a DMM-4065 (hereinafter the same) of National Instruments.

[0068] As shown, when a predetermined voltage is applied, for example, by a short circuit tester, the voltage waveform of a normal electrode assembly increases to a predetermined value determined according to the type of the electrode assembly, and then decreases after a predetermined period of time. Since the electrode assembly before electrolyte is injected is a kind of capacitor, when a voltage is applied to the electrode assembly, charges of a corresponding polarity are collected in each of the positive and negative electrodes, and thus the voltage of the predetermined value (50V in Figure 4 is measured from the electrode assembly as shown in Figure 4 At this time, as shown in Figure 4 , the current shows a predetermined peak value, and then converges to a value close to zero. Since the electrolyte is not injected, the current value is close to zero because the insulation resistance becomes close to infinity.

[0069] Figure 5 is a set of graphs showing a comparison between the voltage-current waveforms of each of a normal electrode assembly and an error failure electrode assembly measured by the electrode assembly failure inspection device 100 of the present application.

[0070] Figure 5 (a) of Figure 4 shows the voltage and current waveforms of a normal electrode assembly similar to Figure 4 . Except that the maximum voltage is 101.65V, the voltage waveform looks similar to the voltage waveform of Figure 5 . In addition, except that the peak current is 5.62mA, the current waveform also looks close to zero. On the other hand, the current waveform of the error failure electrode assembly of (b) of Figure 5 is different. The error failure is a failure due to a circuit disconnection or a pin contact failure. Thus, it can be seen that, in the case of the error failure, the voltage waveform is almost the same as that of the normal electrode assembly (normal waveform) (the maximum voltage is 101.4V), but there is no peak in the current waveform.

[0071] Therefore, according to the inspection method of the present application, in the case where the peak is not present in the current waveform when the voltage waveform of the electrode assembly is a normal waveform, it is determined as a false failure. The voltage and current waveforms can be extracted from data on changes in voltage and current monitored by the failure determination section 40 of the inspection apparatus 100 of the present application (see the above software "LAPVIEW").

[0072] Further, in the failure determination section 40 of the inspection apparatus 100 of the present application, in the case where the peak is not present in the current waveform when the voltage waveform of the electrode assembly is a normal waveform, it is determined as a false failure.

[0073] Meanwhile, depending on the type of the electrode assembly, even when the peak is present in the current waveform, the peak can be smaller than that of a normal electrode assembly. For example, even in the case of a false failure of a pin contact failure, depending on the contact state, a small peak can be measured in the current waveform, instead of no flowing current at all. Therefore, in addition to the case where the peak is not present in the current waveform, even when the peak is smaller than or equal to a predetermined size, it can be regarded as a false failure.

[0074] Therefore, according to the inspection method of the present application, in the case where the peak is not present in the current waveform when the voltage waveform of the electrode assembly is a normal waveform, it is determined as a false failure. The voltage and current waveforms can be extracted from data on changes in voltage and current monitored by the failure determination section 40 of the inspection apparatus 100 of the present application (see the above software "LAPVIEW").

[0075] Further, in the failure determination section 40 of the inspection apparatus 100 of the present application, in the case where the peak is not present in the current waveform when the voltage waveform of the electrode assembly is a normal waveform, it is determined as a false failure.

[0076] Meanwhile, in the waveforms of voltage and current monitored by the inspection apparatus 100 of the present application or the like, even when the current waveform is the same as that of a false failure, when the voltage waveform is different from a normal waveform, it is not determined as a false failure.

[0077] (Second Embodiment)

[0078] According to the present application, a bridge failure and a point failure that can not be measured with a conventional short circuit tester can be detected.

[0079] The bridge failure refers to a failure in which an electrode is separated and the separated part connects the positive and negative electrodes like a bridge to generate a short circuit, and the point failure refers to a failure in which a point-like hole is generated in a separator and thus insulation between the positive and negative electrodes is damaged.

[0080] When insulation between the positive electrode and the negative electrode is damaged, the measured current value in the electrode assembly exceeds the measurement limit of the short circuit tester or exceeds the set upper limit of the current. This is referred to as a "High Fail". Conventional short circuit testers can measure a High Fail, but can not determine whether the High Fail is a bridge failure or a point failure.

[0081] In the fault inspection method of the present application, when a predetermined voltage is applied to the electrode assembly, when the maximum current value measured from the electrode assembly exceeds the set upper limit value, the electrode assembly having a bridge failure and a point failure can be detected from data regarding voltage variation of the electrode assembly for a predetermined period of time.

[0082] The upper limit value of the maximum current value can be a set value determined as a High Fail in the short circuit tester 20. In order to obtain information about the maximum current value of the electrode assembly, the fault determination part 40 of the inspection device 100 of the present application can be connected to the short circuit tester 20 to receive information about detection of a short circuit therefrom. That is, the fault inspection device 100 of the present application can receive information about the current from, for example, the short circuit tester 20, and detect a bridge failure and a point failure from voltage data of the multimeter 30. Alternatively, a bridge failure and a point failure can be detected from voltage and current data measured by the multimeter 30.

[0083] In the case of a bridge failure, since the voltage does not significantly increase even when a voltage is applied by a short circuit tester, the maximum voltage is not greater than that in a point failure. However, when the number of electrode assemblies or battery cells to be measured increases, the maximum voltage of a point failure can not necessarily be greater than that of a bridge failure. This is because, in the case of a bridge failure, the range of variation of the maximum voltage is large depending on the resistance of the separated electrode part. Therefore, it is difficult to distinguish a bridge failure and a point failure only by the magnitude of the voltage.

[0084] In the present embodiment, in view of this, a bridge failure and a point failure are distinguished by a statistical method.

[0085] That is, first, it is determined whether the maximum current value measured from the electrode assembly exceeds the set upper limit value (for example, a current value sufficient to be determined as a High Fail in a short circuit tester).

[0086] When the maximum current value exceeds the upper limit value, a reference is made to a statistical distribution curve of the maximum voltage of a bridge failure and a point failure of the electrode assembly.

[0087] Figure 6 is a set of graphs showing the maximum voltage of a bridge failure and a point failure according to the frequency of each failure.

[0088] Figure 6The data were prepared based on the maximum voltage measured by the DMM-4065 on 164 electrode assemblies during the folding process when the test voltage of the short circuit tester 19073 (model name N2.1) was set to 50V, each of which was determined to have a high fault. Figure 6 , the X-axis represents the maximum voltage, and the Y-axis represents the number of electrode assemblies or battery cells having the corresponding maximum voltage.

[0089] like Figure 6 As shown in (a), although the maximum voltage of a point fault is generally greater than the maximum voltage of a bridge fault, it can be seen that the opposite is possible depending on the electrode assembly. Figure 6 As shown in (b), most bridge faults and point faults occur on the left and right of a point respectively (see Figure 6 The maximum voltage statistical distribution curve connecting the maximum voltages of the electrode assemblies with bridge faults and the maximum voltage statistical distribution curve connecting the maximum voltages of the electrode assemblies with point faults intersect for the first time at this point. Therefore, when the maximum voltage at the point where the maximum voltage statistical distribution curves of the two faults intersect for the first time is taken as Figure 6 When the 15V in the figure is referred to as the threshold maximum voltage, an electrode assembly having a maximum voltage lower than the threshold maximum voltage can be determined as having a bridge fault, and conversely, an electrode assembly having a maximum voltage greater than the threshold maximum voltage can be determined as having a point fault.

[0090] That is, the fault determination part 40 of the fault inspection device 100 of the present invention can determine a bridge fault or a point fault, for example, by comparing a threshold maximum voltage over time and a maximum voltage among the voltages of the electrode assembly, wherein the threshold maximum voltage is determined from a maximum voltage statistical distribution curve of bridge faults and point faults input into a storage part or another database, and the maximum voltage among the voltages of the electrode assembly is measured within a predetermined time period by a multimeter, etc.

[0091] Figure 7 is a graph illustrating another embodiment of maximum voltages of a bridge fault and a point fault according to the frequency of each fault. Figure 7 It was prepared based on data on the maximum voltage measured by the DMM-4065 for 54 electrode assemblies during the folding process when the test voltage of the short circuit tester 19073 (model name E52) was set to 200V, where each electrode assembly was determined to have a high fault failure.

[0092] It can be seen even in the present embodiment that, centered on the threshold maximum voltage (55 V) at which the maximum voltage statistical distribution curves of the two faults first intersect, the bridge fault tends to be biased to the left (lower maximum voltage), and the point fault tends to be biased to the right (higher maximum voltage).

[0093] According to the present application, therefore, the electrode assembly of the bridge fault and the point fault can be easily detected from data on the changes in the voltage and the current of the electrode assembly over a predetermined period of time.

[0094] The above description is merely an example of describing the technical spirit of the present application, and those skilled in the art will understand that various changes can be made in form and details without departing from the spirit and scope of the present application. Accordingly, the drawings disclosed herein are considered to be descriptive rather than restrictive on the technical spirit of the present application, and the scope of the technical spirit of the present application is not limited by these drawings. The scope of the present application should be interpreted by the appended claims together with the full scope of equivalents enjoyed by these claims.

[0095] [Explanation of Reference Numerals]

[0096] 1: positive electrode

[0097] 1a: positive electrode tab (terminal)

[0098] 2: separator

[0099] 3: negative electrode

[0100] 3a: negative electrode tab (terminal)

[0101] 4: case

[0102] 10: electrode assembly

[0103] 20: short circuit tester

[0104] 21: display panel

[0105] 30: multimeter

[0106] 40: fault determination portion

[0107] 50: display portion

[0108] 100: electrode assembly fault inspection device

Claims

1. A device for checking for malfunction of an electrode assembly before injecting electrolyte, the device comprising: a short circuit tester configured to detect a short circuit of the electrode assembly by applying a predetermined voltage to the positive electrode and the negative electrode of the electrode assembly; a multimeter electrically connected to the short circuit tester and configured to measure the voltage and current of the electrode assembly over time; as well as a fault determination section connected to the multimeter and configured to monitor changes in voltage and current measured by the multimeter and determine a type of fault of the electrode assembly based on data on the changes in voltage and current over a predetermined period of time, wherein the fault determination portion detects an electrode assembly having a false fault by comparing a voltage waveform and a current waveform, Here, the fault determination portion determines the fault as the false fault when a peak value of the current waveform determined according to the type of the electrode assembly is less than or equal to a predetermined size when the voltage waveform is a normal waveform.

2. The device according to claim 1, wherein The multimeter is a digital multimeter.

3. The device according to claim 1, wherein The fault determination portion is connected to the short-circuit tester and receives information on short-circuit detection from the short-circuit tester.

4. The device according to claim 1, wherein The fault determination portion determines the fault as the false fault when there is no peak in the current waveform when the voltage waveform is a normal waveform.

5. The device according to claim 1, wherein The fault determination part detects an electrode assembly having a bridge fault and a point fault based on data regarding changes in voltage and current of the electrode assembly having a fault determined as a high fault by the short circuit tester within a predetermined period of time.

6. The device according to claim 5, wherein The fault determination portion determines an electrode assembly having a maximum voltage lower than a threshold maximum voltage as having the bridge fault, wherein the threshold maximum voltage is the maximum voltage at a point where maximum voltage statistical distribution curves of the electrode assembly having the bridge fault and the electrode assembly having the point fault first overlap with each other.

7. The device according to claim 5, wherein The fault determination portion determines an electrode assembly having a maximum voltage greater than a threshold maximum voltage as having the point fault, wherein the threshold maximum voltage is the maximum voltage at a point where maximum voltage statistical distribution curves of the electrode assembly having the bridge fault and the electrode assembly having the point fault first overlap with each other.

8. A method for detecting a fault in an electrode assembly before injecting electrolyte, the method comprising: measuring a voltage and a current of the electrode assembly over time by applying a predetermined voltage to the positive electrode and the negative electrode of the electrode assembly; as well as determining at least one fault type from among a false fault, a bridge fault, and a point fault based on data on changes in voltage and current over a predetermined period of time, Here, when the voltage waveform of the electrode assembly is a normal waveform, a peak value of the current waveform determined according to the type of the electrode assembly is less than or equal to a predetermined value, it is determined to be the error fault.

9. The method according to claim 8, wherein When there is no peak in the current waveform when the voltage waveform of the electrode assembly is a normal waveform, it is determined to be the false fault.

10. The method according to claim 8, wherein When a maximum current value measured from the electrode assembly exceeds a set upper limit value, the electrode assembly having the bridge fault and the point fault is detected based on data regarding a change in voltage of the electrode assembly within a predetermined period of time.

11. The method according to claim 10, wherein: An electrode assembly having a maximum voltage lower than a threshold maximum voltage is determined to have the bridge fault, wherein the threshold maximum voltage is the maximum voltage at a point where the maximum voltage statistical distribution curves of the electrode assembly having the bridge fault and the electrode assembly having the point fault first overlap with each other.

12. The method according to claim 10, wherein: An electrode assembly having a maximum voltage greater than a threshold maximum voltage is determined to have the point fault, wherein the threshold maximum voltage is the maximum voltage at a point where the maximum voltage statistical distribution curves of the electrode assembly having the bridge fault and the electrode assembly having the point fault first overlap with each other.

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