Method and apparatus for analyzing deformation of secondary battery

Abstract

A method and apparatus for analyzing deformation of a secondary battery having an electrode assembly with a tab accommodated in a case, the method including: acquiring a first image by performing computed tomography imaging on the secondary battery; calculating a first position of the tab from the first image; acquiring the number of charge and discharge cycles of the secondary battery after the secondary battery is degraded by charging and discharging the secondary battery a plurality of times; acquiring a second image by performing computed tomography imaging on the degraded secondary battery; calculating a second position of the tab from the second image; and determining that the electrode assembly is deformed if the variation between the first position and the second position is greater than a reference value.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based on and claims the benefit of priority of Korean Patent Application No. 10-2023-0136717 filed in the Korean Intellectual Property Office on October 13, 2023, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure relates to a method and apparatus for analyzing deformation of a secondary battery. Background Art

[0004] Secondary batteries are subjected to continuous charging and discharging, which causes various electrochemical reactions within the battery, leading to battery degradation and performance degradation. In particular, the internal deformation of the battery during charging and discharging is a factor that affects degradation and performance degradation. In order to analyze the degradation phenomenon, destructive analysis methods are mainly used, which usually involve disassembling the battery and performing the analysis. However, this analysis method inevitably causes damage to the interior of the battery during the disassembly process, making it difficult to determine the actual cause of performance degradation, and is limited in identifying the degradation trend as charging and discharging proceed.

[0005] The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure. Summary of the invention

[0006] An embodiment includes a method for analyzing deformation of a secondary battery having an electrode assembly with a terminal tab accommodated in a housing. The method includes: acquiring a first image by performing computed tomography (CT) imaging on the secondary battery; calculating a first position of the terminal tab from the first image; acquiring the number of charge and discharge cycles of the secondary battery after the secondary battery is charged and discharged multiple times so that the secondary battery is degraded; acquiring a second image by performing CT imaging on the degraded secondary battery, calculating a second position of the terminal tab from the second image; and determining that the electrode assembly is deformed if a change between the first position and the second position is greater than a reference value.

[0007] The first position and the second position may be defined as an angle between a first straight line connecting an intersection of a core major diameter and a core minor diameter of the electrode assembly and the tab, and a second straight line connecting the intersection and a winding rear end of the electrode assembly.

[0008] The secondary battery may have a cylindrical shape.

[0009] The electrode assembly may be wound into a cylindrical shape in which a positive electrode plate, a separator, and a negative electrode plate are stacked.

[0010] The tab may include a positive electrode tab coupled to the positive electrode plate or a negative electrode tab coupled to the negative electrode plate.

[0011] The winding rear end may be a winding rear end of a positive electrode plate or a negative electrode plate.

[0012] The reference value may be 1% to 5%.

[0013] An embodiment includes an apparatus for analyzing deformation of a secondary battery, the secondary battery having an electrode assembly with a terminal tab contained in a housing. The apparatus includes: a control circuit, a processor installed in the control circuit, and a memory installed in the control circuit and operably connected to the processor, wherein the processor executes program code stored in the memory and is configured to: acquire a first image by performing computed tomography (CT) imaging on the secondary battery; calculate a first position of the terminal tab from the first image; acquire the number of charge and discharge cycles of the secondary battery after the secondary battery is charged and discharged multiple times so that the secondary battery is degraded; acquire a second image by performing CT imaging on the degraded secondary battery; calculate a second position of the terminal tab from the second image; and determine that the electrode assembly is deformed if the amount of change between the first position and the second position is greater than a reference value.

[0014] The first position and the second position may be defined as an angle between a first straight line connecting an intersection of a core major diameter and a core minor diameter of the electrode assembly and the tab, and a second straight line connecting the intersection and a winding rear end of the electrode assembly.

[0015] The secondary battery may have a cylindrical shape.

[0016] The electrode assembly may be wound into a cylindrical shape in which a positive electrode plate, a separator, and a negative electrode plate are stacked.

[0017] The tab may include a positive electrode tab coupled to the positive electrode plate or a negative electrode tab coupled to the negative electrode plate.

[0018] The winding rear end may be a winding rear end of a positive electrode plate or a negative electrode plate.

[0019] The reference value may be 1% to 5%. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Features will become apparent to those skilled in the art by describing exemplary embodiments in detail with reference to the accompanying drawings, in which:

[0021] Figure 1 is a block diagram illustrating a configuration of an apparatus for analyzing deformation of an exemplary secondary battery according to one or more embodiments of the present disclosure.

[0022] Figure 2is a flow chart illustrating a method for analyzing deformation of an exemplary secondary battery according to one or more embodiments of the present disclosure.

[0023] Figure 3A and Figure 3B are longitudinal sectional views and cross-sectional views of an exemplary secondary battery according to one or more embodiments of the present disclosure.

[0024] Figure 4A and Figure 4B is a graph showing the amount of change in the position of a tab with respect to the number of charge and discharge cycles of an exemplary secondary battery according to one or more embodiments of the present disclosure. DETAILED DESCRIPTION

[0025] In the accompanying drawings, the dimensions of layers and regions may be exaggerated for clarity of illustration. It will also be understood that when a layer or element is referred to as being "on" another layer or element, it can be directly on the other layer or element, or there can also be intervening layers. Further, it will be understood that when a layer is referred to as being "under" another layer, it can be directly under the other layer, and there can also be one or more intervening layers. In addition, it will be understood that when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or there can also be one or more intervening layers. Throughout the text, the same reference numerals refer to the same elements.

[0026] In addition, according to the present disclosure, the control unit (controller) and / or other related devices or components can be implemented using any suitable hardware, firmware (e.g., dedicated semiconductors), software, or a suitable combination of software, firmware and hardware. For example, according to the present disclosure, the control unit (controller) and / or other related devices or components can be formed on a single integrated circuit chip or formed on a separate integrated circuit chip. In addition, the various components of the control unit (controller) can be implemented on a flexible printed circuit film, and can be formed on a substrate equivalent to a carrier package, a printed circuit board or a control unit (controller). In addition, the various components of the control unit (controller) can be processes or threads running on one or more processors in one or more computing devices, executing computer program instructions and interacting with other system components for performing various functions described herein. Computer program instructions can be stored in a memory, which can be implemented in a computing device using a standard storage device (e.g., a random access memory (RAM)). Computer program instructions can also be stored in other non-temporary computer-readable media (e.g., a CD-ROM or a flash drive, etc.). In addition, one of ordinary skill in the art should recognize that, without departing from the spirit and scope of the exemplary embodiments of the present disclosure, the functionality of various computing devices may be combined or integrated into a single computing device, or the functionality of a particular computing device may be distributed across one or more other computing devices.

[0027] Figure 1 1 is a block diagram showing a configuration of an apparatus for analyzing deformation of an exemplary secondary battery (hereinafter, also referred to as a deformation analysis apparatus) 100 according to one or more embodiments of the present disclosure. Figure 1 As shown in , the deformation analysis device 100 for a secondary battery may include an input device 101, an output device 102, a control circuit 103, a central processing unit (CPU) 104, a memory 105, and a program code 106. In some embodiments, the deformation analysis device 100 may further include a CT imaging device 107 and / or a charging / discharging device 108.

[0028] The control circuit 103 may execute the program code 106 stored in the memory 105 through the CPU 104, and may control the overall operation of the deformation analysis device 100. In some embodiments, the program code 106 may include an image analysis tool, for example, "ImageJ" which is open source software that can be downloaded online. However, the specific image analysis tool may vary.

[0029] The deformation analysis device 100 may receive data or information input by a user through an input device 101 (e.g., a keyboard or a mouse), and output an image or sound through an output device 102 (e.g., a monitor or a speaker). In some examples, the deformation analysis device 100 may directly or indirectly receive a CT image from a CT imaging device 107. In some embodiments, the deformation analysis device 100 may directly or indirectly receive a charge and discharge cycle number from a charge / discharge device 108. In one or more embodiments, the deformation analysis device 100 may receive data paired with a CT image and a charge and discharge cycle number.

[0030] In the memory 105 , various settings (eg, reference values ​​or reference ratios) for implementing the embodiments of the present disclosure, such as received CT images, received charging and discharging cycle numbers, and a program code 106 for controlling the operation of the deformation analysis device 100 may be stored.

[0031] The CT imaging device 107 can acquire a first image by performing CT imaging on the secondary battery before the charge and discharge cycle is performed, acquire a second image by performing CT imaging on the secondary battery after the charge and discharge cycle is performed, and transmit the first image and the second image directly or indirectly to the deformation analysis device 100.

[0032] In some embodiments, the CT imaging device 107 may be controlled by direct control of the control circuit 103, so that the control circuit 103 may directly acquire or receive images from the CT imaging device 107. In one or more embodiments, the first image and the second image acquired from the CT imaging device 107 may be indirectly provided to the control circuit 103 through the input device 101.

[0033] The charging / discharging device 108 can charge the secondary battery to be subjected to CT imaging by providing current and voltage to the secondary battery, or can discharge the secondary battery by connecting a load to the secondary battery. In some embodiments, the charging / discharging device 108 can be controlled by direct control of the control circuit 103, so that the secondary battery can be charged or discharged by the charging / discharging device 108. In an embodiment, the secondary battery can be charged or discharged by the charging / discharging device 108 without the intervention of the control circuit 103.

[0034] In some embodiments, the charge / discharge device 108 may be controlled by direct control of the control circuit 103, so that the control circuit 103 may directly obtain or receive the charge and discharge cycle number from the charge / discharge device 108. In an embodiment, the charge and discharge cycle number obtained from the charge / discharge device 108 may be indirectly provided to the control circuit 103 through the input device 101.

[0035] In one or more embodiments, a CT image for each number of charge and discharge cycles of the secondary battery may be provided to the control circuit 103 in the form of mutually matching data. In other words, whenever a charge and discharge cycle of the secondary battery passes, CT imaging may be performed on the secondary battery, and therefore, data including the number of charge and discharge cycles and the CT image may be provided directly or indirectly to the control circuit 103. In some embodiments, CT imaging may be performed approximately every 50 to approximately 100 cycles. However, the frequency of CT imaging may vary.

[0036] Figure 2 FIG. 1 is a flow chart showing one example of a method for analyzing deformation of an exemplary secondary battery according to one or more embodiments of the present disclosure. Figure 2As shown in, a method for analyzing the deformation of an exemplary secondary battery may include: acquiring a first image by performing CT imaging on the secondary battery (step S1), which may be a first step; calculating a first position of a terminal from the first image (step S2), which may be a second step; obtaining the number of charge and discharge cycles of the secondary battery (step S3), which may be a third step; acquiring a second image by performing CT imaging on the secondary battery (step S4), which may be a fourth step; calculating a second position of the terminal from the second image (step S5), which may be a fifth step; and determining that the secondary battery is deformed if the amount of change between the first position and the second position is greater than a reference value (step S6), which may be a sixth step.

[0037] In step S1, the control circuit 103 may acquire or receive a first image from the CT imaging device 107. In some embodiments, the secondary battery may be CT imaged by the CT imaging device 107, and the first image after CT imaging may be transmitted from the CT imaging device 107 to the control circuit 103. As described above, the CT imaging device 107 may operate in response to a control signal from the control circuit 103, or may operate independently to transmit the first image directly or indirectly to the control circuit 103.

[0038] In step S2, the control circuit 103 can calculate the first position of the terminal tab in the electrode assembly from the first image. As will be explained in further detail below, the first position can be defined as the angle between a first straight line connecting the intersection of the core major diameter and the core minor diameter of the electrode assembly with the terminal tab and a second straight line connecting the intersection with the winding rear end of the electrode assembly.

[0039] In step S3, the control circuit 103 may obtain or receive the number of charge and discharge cycles of the secondary battery from the charge / discharge device 108. In one or more embodiments, the secondary battery may be charged and discharged multiple times by the charge / discharge device 108, and the number of cycles after charging and discharging may be transmitted from the charge / discharge device 108 to the control circuit 103. As described above, the charge / discharge device 108 may be operated by a control signal from the control circuit 103, or may be operated independently to charge and discharge the secondary battery multiple times, and the number of charge and discharge cycles may be transmitted directly or indirectly to the control circuit 103. In some embodiments, the secondary battery may deteriorate or age due to the charging and discharging of the secondary battery, and the housing and / or electrode assembly of the secondary battery may be deformed. In other words, as the secondary battery deteriorates, the position of the tab connected to the electrode assembly may change.

[0040] In step S4, the control circuit 103 may acquire or receive the second image from the CT imaging device 107. In an embodiment, the secondary battery may be CT imaged by the CT imaging device 107, and the second image after CT imaging may be transmitted from the CT imaging device 107 to the control circuit 103. As described above, the CT imaging device 107 may be operated by a control signal from the control circuit 103, or may be independently operated to transmit the second image directly or indirectly to the control circuit 103.

[0041] In step S5, the control circuit 103 can calculate the second position of the wiring tab from the second image. Similar to the above description, the second position can be defined as the angle between a first straight line connecting the intersection of the core long diameter and the core short diameter in the electrode assembly and the wiring tab, and a second straight line connecting the intersection and the winding rear end of the electrode assembly.

[0042] In some embodiments, the core long diameter may be referred to as the core major axis, and the core short diameter may be referred to as the core minor axis. In geometry, the major axis and minor axis of a deformed or distorted circle may represent two perpendicular diameters of an ellipse. An ellipse is a closed curve in which the sum of the distances from a point on the curve to two fixed points (called foci) remains constant. The longer diameter of an ellipse may be referred to as the major axis, and the shorter diameter may be referred to as the minor axis. That is, the major axis is the longest diameter of the ellipse, which passes through the center and the two foci, and its length may be the major diameter. In addition, the minor axis may be a minor diameter perpendicular to the major axis, which passes through the center like the major axis, and its length may be the minor axis diameter.

[0043] In general, in a completely symmetrical circle, the major axis and the minor axis can be the same because the distance through the center of the circle is always the same no matter from which direction the distance is measured. That is, if the core of the above-mentioned electrode assembly forms a perfect circle without deformation or distortion, the major axis and the minor axis can be the same. However, in most cases, as the number of charge and discharge cycles passes, the core of the electrode assembly may be deformed or distorted, and therefore, the lengths of the major axis and the minor axis may be different. In this way, the term "major diameter" may refer to the longer diameter of the ellipse corresponding to the major axis in this article, and the term "minor diameter" may refer to the shorter diameter corresponding to the minor axis in this article, but it should be understood that in some cases, the "long length" and the "short length" may be the same.

[0044] In step S6, if the change between the first position and the second position is greater than a preset reference value, the control circuit 103 may determine that the electrode assembly of the secondary battery has been deformed. In some embodiments, the control circuit 103 may output the first image and the second image, the first position and the second position, the change between the first position and the second position, the reference value, and the occurrence of deformation through the output device 102.

[0045] Various methods for analyzing deformation of a secondary battery according to the present disclosure will be explained below.

[0046] [Preparation of Secondary Battery]

[0047] A cylindrical secondary battery having a core-shaped electrode assembly accommodated in a cylindrical case (or a cylindrical can) may be first prepared.

[0048] Figure 3A and Figure 3B are longitudinal sectional views and cross-sectional views of an exemplary secondary battery according to one or more embodiments. Figure 3B The electrode assembly is greatly enlarged to show the winding state of the electrode assembly. In fact, the center of the electrode assembly has an approximately circular empty space (or core), and there is almost no empty space between the outside of the electrode assembly and the inner surface of the shell (or can). In practice, the electrode assembly can be wound into an approximately perfect circle, and Figure 3B It is shown enlarged to illustrate the winding structure as described above. In addition, a person skilled in the art will understand that the corresponding Figure 3B CT images and Figure 3B The shadows in are opposite.

[0049] In some embodiments, the core-shaped electrode assembly 30 of the secondary battery 1 can be housed in a cylindrical shell 10, and after injecting an electrolyte so that the electrode assembly 30 is immersed in the cylindrical shell 10 (optional), it can be manufactured by connecting the cap assembly 20 to the open top end of the cylindrical shell 10. In one or more embodiments, the electrode assembly 30 can be a core form manufactured by stacking the positive electrode plate 31 and the negative electrode plate 32 in a state where the separator 33 is inserted between the positive electrode plate 31 and the negative electrode plate 32 and then winding in one direction. Figure 3B , 30S refers to the winding front end where the winding of the electrode assembly 30 starts, and 30E refers to the winding rear end where the winding of the electrode assembly 30 ends. In some embodiments, the electrode assembly 30 may be in the form of an electrode core manufactured by stacking the positive electrode plate 31 and the negative electrode plate 32 with the separator 33 inserted between the positive electrode plate 31 and the negative electrode plate 32 and then winding them in one direction. Figure 3B, 30S refers to the winding front end where the winding of the electrode assembly 30 starts, and 30E refers to the winding rear end where the winding of the electrode assembly 30 ends. In an embodiment, the phrases "winding front end" and "winding rear end" may refer to specific areas during the manufacturing process of the electrode assembly. The process may involve the generation of a winding or curled electrode structure commonly used in batteries (e.g., lithium-ion battery cells). Specifically, in a circular electrode assembly of a secondary battery, the winding front end may refer to the initial part or point where the winding of the electrode plate begins. This may be where the first layer of the electrode plate is attached to the central core or diaphragm or is wrapped around the central core or diaphragm. In a circular electrode assembly of a secondary battery, the winding rear end may refer to the last part or point where the winding process ends. This may be where the last layer of the electrode plate is attached and fixed. In order to ensure that the electrode plate is firmly fixed and there are no loose ends or edges, the winding process at the winding rear end may be properly terminated.

[0050] In one or more embodiments, the cylindrical shell 10 may be made of metal (e.g., steel, stainless steel, or nickel-plated steel). In some embodiments, the cylindrical shell may include a housing portion in which the electrode assembly is accommodated and the upper portion may be open. In an embodiment, the cylindrical shell 10 may be made of metal (e.g., steel, stainless steel, or nickel-plated steel). In one or more embodiments, the cylindrical shell 10 may include a housing portion in which the electrode assembly is accommodated and the upper portion may be open. In some embodiments, the cylindrical shell may include a housing portion in which the electrode assembly may be accommodated and the upper portion thereof may be opened. In one or more embodiments, the curved curling portion may be provided to be sealed after the cap assembly 20 is coupled to the opened upper portion of the cylindrical shell 10, and in order to fix the cap assembly 20, the upper end may be bent to provide a curling portion. In an embodiment, the curling portion may be provided at a portion where the cap assembly and the cylindrical shell contact each other, and may be recessed toward the inside of the cylindrical shell. In one or more embodiments, the cylindrical shell may be used as a negative electrode terminal connected to an external circuit. In an embodiment, the cap assembly 20 may be configured so that the upper cover and the safety vent may be in close contact with an airtight gasket installed in a space formed on the inner surface of the curled portion and the curled edge portion of the cylindrical shell 10. The central portion of the upper cover may protrude upward, and therefore, may be used as a positive electrode terminal connected to an external circuit. In some embodiments, a core 34 in the form of an empty space may be provided at the center of the electrode assembly 30 wound into a core structure. In an embodiment, a center pin (not shown) made of a cylindrical metal material may be inserted into the core 34 to provide additional strength to the electrode assembly, and in some cases, the center pin may be removed after the electrode is welded to the cylindrical shell or the cap assembly. In one or more embodiments, the negative electrode tab may protrude from the lower end of the electrode assembly and be welded to the bottom surface of the cylindrical shell, and the positive electrode tab may protrude from the upper end of the electrode assembly and be welded to the cap assembly.

[0051] In some embodiments, the area of ​​the secondary battery 1 where CT imaging is performed may include a first area adjacent to the cap assembly and / or a second area adjacent to the bottom surface of the can. In other words, the first area may be approximately the upper portion of the can and the electrode assembly, and the second area may be approximately the lower portion of the can and the electrode assembly. In some examples, the area where CT imaging is performed may further include a third area, which may be approximately the middle portion of the can and the electrode assembly.

[0052] The cylindrical secondary battery described in this article is provided only by way of example for understanding the present disclosure, and the present disclosure is not limited to the cylindrical secondary battery. As an example, the present disclosure may also be applied to 18650 (18 mm in diameter, 65 mm in height) cylindrical batteries, 21700 (21 mm in diameter, 70 mm in height) cylindrical batteries, or 46800 (46 mm in diameter, 80 mm in height) cylindrical batteries, and may also be applied to cylindrical batteries to be manufactured in the future.

[0053] [First CT imaging]

[0054] When a cylindrical secondary battery is prepared in the above manner, a first image of a cross section perpendicular to the winding axis of the electrode assembly can be obtained by a CT imaging device. As described above, the first image may include an image obtained by photographing a first region (e.g., a portion above the electrode assembly), a second region (e.g., a portion below the electrode assembly), and / or a third region (e.g., a middle portion of the electrode assembly) of the secondary battery. The image obtained from the CT imaging device can be transmitted directly or indirectly to the control circuit 103 of the deformation analysis device 100 of the secondary battery.

[0055] [Calculation of the first position of the lug]

[0056] When the first image is acquired by CT imaging, the first position of the tab 311 (e.g., a positive electrode tab or a negative electrode tab) appearing on the first image can be calculated. In some embodiments, the first position can be defined as the angle (θ) between a first straight line and a second straight line, the first straight line connecting the intersection of the core long diameter and the core short diameter of the electrode assembly and the tab 311, and the second straight line connecting the intersection and the winding rear end 30E of the electrode assembly. In one or more embodiments, one end of the first straight line may face the intersection, and the other end of the first straight line may face the center of the tab, one end of the tab, or the other end of the tab. In some embodiments, one end of the second straight line may face the intersection, and the other end of the second straight line may face the winding rear end of the positive electrode plate or the winding rear end of the negative electrode plate.

[0057] [Performance of charge and discharge cycle of secondary battery]

[0058] As described above, the secondary battery can be charged and discharged by the charging / discharging device 108. When the secondary battery is charged and discharged once, it can be defined that one cycle or one life of the secondary battery has passed. In some embodiments, an image can be acquired from the CT imaging device every time the charging / discharging device passes about 50 to about 100 cycles of the secondary battery.

[0059] The charging / discharging device 108 may include a fixture on which a secondary battery is mounted, a charging circuit connected to the secondary battery to provide charging power, a discharging circuit connected to the secondary battery and operating as a load, a positive electrode pin and a negative electrode pin that connect the charging circuit or the discharging circuit to the positive electrode terminal and the negative electrode terminal of the secondary battery, respectively, and a computer capable of storing the charging / discharging time, the charging / discharging voltage, the charging / discharging current, and the number of cycles. The number of cycles obtained from the charging / discharging device may be directly or indirectly transmitted to the control circuit 103 of the deformation analysis device 100 of the secondary battery. In one or more embodiments, the number of cycles may also be manually input through an input device when the image obtained from the CT imaging device 107 is transmitted to the control circuit 103 without the intervention of the charging / discharging device 108.

[0060] [Second CT imaging]

[0061] As described above, after the secondary battery deteriorates as the charge and discharge cycles of the secondary battery proceed, a second image of a cross section perpendicular to the winding axis of the electrode assembly can be acquired by a CT imaging device. In some embodiments, the second image can be acquired by photographing a first region of the secondary battery (e.g., the portion above the housing and the electrode assembly), a second region of the secondary battery (e.g., the portion below the housing and the electrode assembly), or a third region of the secondary battery (e.g., the middle of the housing and the electrode assembly). In one or more embodiments, the second image may be an image for the same region as the region photographed when the first image was acquired. The image acquired from the CT imaging device 107 may be transmitted directly or indirectly to the control circuit 103 of the deformation analysis device 100 of the secondary battery.

[0062] [Calculation of the second position of the lug]

[0063] After acquiring the second image by CT imaging, the second position of the tab 311 (e.g., a positive electrode tab or a negative electrode tab) appearing on the second image can be calculated. In some embodiments, the second position can be defined as the angle (θ) between the first straight line and the second straight line, the first straight line connecting the intersection of the core long diameter and the core short diameter of the electrode assembly and the tab 311, and the second straight line connecting the intersection and the winding rear end 30E of the electrode assembly. In an embodiment, one end of the first straight line may face the intersection, and the other end of the first straight line may face the center of the tab, one end of the tab, or the other end of the tab. In one or more embodiments, one end of the second straight line may face the intersection, and the other end of the second straight line may face the winding rear end of the positive electrode plate or the winding rear end of the negative electrode plate.

[0064] [Determination of deformation]

[0065] As described above, after calculating the first position and the second position of the terminal tab, the deformation can be determined by the amount of change between the first position and the second position. In some embodiments, when acquiring the first image and the second image, the number of charge and discharge cycles can also be acquired. Therefore, it can be determined whether the electrode is deformed as the number of cycles of the secondary battery passes. In one or more embodiments, the amount of change (%) of the terminal tab position can be calculated using the following equation.

[0066] Amount of change in the lug position (%)=[(second position of the lug−first position of the lug) / first position of the lug]*100%.

[0067] In an embodiment, if the amount of change in the terminal tab is higher than a reference value, it can be determined that deformation has occurred in the electrode assembly. In some embodiments, the reference value may be about 1% to 5%. The above reference value may vary depending on the electrochemical properties, size, use environment, etc. of the secondary battery.

[0068] In general, if there is no deformation in the electrode assembly (e.g., electrode), there will be no change between the first position obtained from the first image of the secondary battery and the second position obtained from the second image of the secondary battery. However, as the number of charge and discharge cycles of the secondary battery increases, the electrode assembly repeatedly expands and contracts, and therefore, the electrode assembly may be deformed. In an example embodiment, the position of the terminal tab 311, the position of the winding front end 30S, or the position of the winding rear end 30E in the electrode assembly changes. In view of this, the first position of the terminal tab can be calculated from the first image, the second position of the terminal tab can be calculated from the second image, and when the amount of change between the first position and the second position is greater than a preset reference value, it can be determined that the shell and / or the electrode assembly is deformed.

[0069] Figure 4A and Figure 4B is a graph showing the change in the position of the terminal tab with respect to the number of charge and discharge cycles of an exemplary secondary battery. Figure 4A and Figure 4B In FIG. 1 , the X axis represents the number of charge and discharge cycles, the Y axis represents the amount of change (%) in the position of the terminal tab, and A1 to A7 are numbers assigned to the secondary batteries analyzed. In addition, Figure 4A The change in the positive electrode tab is shown, and Figure 4B The amount of change is shown for the negative electrode tab.

[0070] like Figure 4A and Figure 4BAs shown in , it can be seen that the amount of change in the position of the terminal tab increases with the increase in the number of charge and discharge cycles. As an example, as the number of charge and discharge cycles passes through about 650 times, the amount of change in the position of the positive electrode terminal tab may increase by about more than 4.4%, and the amount of change in the position of the negative electrode terminal tab may increase by about more than 4.6%. Therefore, in an embodiment, when the amount of change in the position of the terminal tab is higher than about 4%, it can be determined that the electrode assembly is deformed inside the housing.

[0071] As described above, according to an embodiment of the present disclosure, in an apparatus and method for analyzing deformation of a secondary battery, a first image corresponding to an initial stage of the secondary battery and a second image showing the life span of the secondary battery can be acquired in a direction perpendicular to the winding axis of the electrode assembly, a first position and a second position can be calculated from the first image and the second image, and whether the electrode assembly is deformed can be determined based on the amount of change in the first position and the second position. Therefore, according to an embodiment of the present disclosure, whether the electrode assembly provided in the secondary battery is deformed can be accurately determined in a non-destructive manner without disassembling the secondary battery.

[0072] As described above, the present disclosure provides an apparatus and method for analyzing deformation of a secondary battery, by which electrode deformation of a secondary battery can be accurately diagnosed by using a CT (Computed Tomography) image, a non-destructive analysis method.

[0073] Example embodiments have been disclosed herein, and although specific terms are employed, they are used and interpreted in a general and descriptive sense only and not for purposes of limitation. In some cases, it will be apparent to one of ordinary skill in the art at the time of filing this application that features, characteristics, and / or elements described in conjunction with a particular embodiment may be used alone or in combination with features, characteristics, and / or elements described in conjunction with other embodiments, unless otherwise specifically indicated. Therefore, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the spirit and scope of the invention as set forth in the following claims.

Claims

1. A method for analyzing deformation of a secondary battery having an electrode assembly with a terminal tab accommodated in a housing, the method comprising: acquiring a first image by performing computed tomography imaging on the secondary battery; calculating a first position of the lug from the first image; After the secondary battery is charged and discharged multiple times so that the secondary battery deteriorates, obtaining the number of charge and discharge cycles of the secondary battery; acquiring a second image by performing computer tomography imaging on the degraded secondary battery; calculating a second position of the lug from the second image; as well as If the amount of change between the first position and the second position is greater than a reference value, it is determined that the electrode assembly is deformed.

2. The method according to claim 1, wherein: The first position and the second position are defined as the angle between a first straight line connecting the intersection of the core major diameter and the core minor diameter of the electrode assembly and the wiring tab, and a second straight line connecting the intersection and the winding rear end of the electrode assembly.

3. The method according to claim 1, wherein: The secondary battery has a cylindrical shape.

4. The method according to claim 2, wherein: The electrode assembly is wound into a cylindrical shape in which a positive electrode plate, a separator, and a negative electrode plate are stacked.

5. The method according to claim 4, wherein: The tab includes a positive electrode tab coupled to the positive electrode plate or a negative electrode tab coupled to the negative electrode plate.

6. The method according to claim 4, wherein: The winding rear end is a winding rear end of the positive electrode plate or the negative electrode plate.

7. The method according to claim 1, wherein: The reference value is 1% to 5%.

8. A device for analyzing deformation of a secondary battery, the secondary battery having an electrode assembly with a terminal tab accommodated in a housing, the device comprising: Control circuit; a processor installed in the control circuit; as well as a memory installed in the control circuit and operably coupled to the processor, wherein the processor executes program code stored in the memory and is configured to: acquiring a first image by performing computed tomography imaging on the secondary battery; calculating a first position of the lug from the first image; After the secondary battery is charged and discharged multiple times so that the secondary battery deteriorates, obtaining the number of charge and discharge cycles of the secondary battery; acquiring a second image by performing computer tomography imaging on the degraded secondary battery; calculating a second position of the lug from the second image; and If the amount of change between the first position and the second position is greater than a reference value, it is determined that the electrode assembly is deformed.

9. The device according to claim 8, wherein: The first position and the second position are defined as the angle between a first straight line connecting the intersection of the core major diameter and the core minor diameter of the electrode assembly and the wiring tab, and a second straight line connecting the intersection and the winding rear end of the electrode assembly.

10. The device according to claim 8, wherein: The secondary battery has a cylindrical shape.

11. The device according to claim 9, wherein: The electrode assembly is wound into a cylindrical shape in which a positive electrode plate, a separator, and a negative electrode plate are stacked.

12. The device according to claim 11, wherein The tab includes a positive electrode tab coupled to the positive electrode plate or a negative electrode tab coupled to the negative electrode plate.

13. The device according to claim 11, wherein: The winding rear end is a winding rear end of the positive electrode plate or the negative electrode plate.

14. The device according to claim 11, wherein: The reference value is 1% to 5%.

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