Apparatus for manufacturing secondary battery and method for manufacturing secondary battery using the same

Abstract

An apparatus for manufacturing a secondary battery according to an exemplary embodiment includes an analyzer configured to generate a merged image including multiple portions of the sheet of material based on multiple images of the sheet of material, and to determine a spatial frequency of periodic defects in the sheet of material based on the merged image.

Description

[Technical Field]

[0001] The present invention relates to an apparatus for manufacturing a secondary battery and a method for manufacturing a secondary battery using the same. This application claims the benefit of Korean Application No. 10-2023-0037224 filed on March 22, 2023, and Korean Application No. 10-2023-0102390 filed on August 4, 2023, which are incorporated herein by reference in their entireties. [Background technology]

[0002] Secondary batteries, unlike primary batteries, can be charged and discharged multiple times. Secondary batteries are widely used as energy sources for a variety of wireless devices, such as handsets, laptops, and wireless vacuum cleaners. In recent years, improvements in energy density and economies of scale have dramatically reduced the manufacturing costs of electrically powered hybrid electric vehicles (HEVs) and battery electric vehicles (BEVs). As the driving range of BEVs has increased to the same level as that of fuel-powered vehicles, the primary use of secondary batteries has shifted from mobile devices to mobility.

[0003] The basic unit of a secondary battery is the battery cell, which can be classified according to the shape of the battery case into cylindrical batteries, in which the electrode assembly is housed in a cylindrical metal can, prismatic batteries, in which the electrode assembly is housed in a prismatic metal can, and pouch batteries, in which the electrode assembly is housed in an aluminum laminate sheet pouch case. Summary of the Invention [Problem to be solved by the invention]

[0004] The problem to be solved by the technical idea of ​​the present invention is to provide an apparatus for manufacturing a secondary battery with improved reliability and a method for manufacturing a secondary battery using the same. [Means for solving the problem]

[0005] To solve the above-mentioned problems, an apparatus for manufacturing a secondary battery according to an exemplary embodiment of the present invention includes a first roll and a second roll configured to move a sheet of material, an inspector configured to generate a plurality of images by photographing a plurality of portions of the sheet of material, some of the plurality of images including periodic defects, and an analyzer configured to generate a merged image including the plurality of portions of the sheet of material based on the plurality of images of the sheet of material, and the analyzer is configured to determine the spatial frequency of the periodic defects in the sheet of material based on the merged image.

[0006] The merged image is created by merging multiple images along a first direction, which is the elongation direction of the sheet of material.

[0007] Each of the plurality of images includes an identifying mark from one of the first roll and the second roll, and the analyzer merges the plurality of images based on the identifying mark.

[0008] The analyzer prevents overlapping of portions of the sheet of material in the merged image based on the identifying indicia.

[0009] The merged image is elongated in a first direction, which is the elongation direction of the sheet of material, and in a second direction perpendicular to the first direction.

[0010] Determining the spatial frequencies of the periodic defects includes performing a Fourier transform in a first direction on the merged image to generate a frequency domain image of the merged image.

[0011] The Fourier transform is a discrete Fourier transform.

[0012] The analyzer is configured to determine that at least one of the first roll and the second roll corresponds to frequencies in the frequency domain image having intensities above a threshold.

[0013] Performing a Fourier transform on the merged image includes dividing the merged image into a plurality of pixel arrays elongated in a first direction and arranged in a second direction, and performing a Fourier transform on each of the plurality of pixel arrays.

[0014] The Fourier transform is a fast Fourier transform.

[0015] Performing a Fourier transform on the merged image includes generating a compressed image by adding values ​​of pixels that overlap in the second direction in the merged image, and performing a Fourier transform on the compressed image.

[0016] The apparatus further includes a pressure roll configured to apply pressure to the sheet of material.

[0017] The apparatus further includes a die coater configured to coat the sheet of material with the electrode slurry.

[0018] According to an exemplary embodiment, an apparatus for manufacturing a secondary battery is provided, the apparatus including: a conveyor belt configured to move a sheet of material; an inspector configured to generate a plurality of images by photographing a plurality of portions of the sheet of material; and an analyzer configured to generate a merged image including the plurality of portions of the sheet of material based on the plurality of images of the sheet of material, the analyzer configured to analyze spatial frequencies of periodic defects in the sheet of material based on the merged image.

[0019] The apparatus further includes a laser notcher configured to apply a laser to the sheet of material.

[0020] According to an exemplary embodiment, a method for manufacturing a secondary battery is provided, the method including the steps of photographing multiple portions of a sheet of material to generate multiple images of the sheet of material, the sheet of material being moved by a first roll and a second roll, generating a merged image including the multiple portions of the sheet of material based on the multiple images of the sheet of material, and performing frequency analysis on the merged image.

[0021] Each of the plurality of images includes an identification mark from one of the first roll and the second roll, and the plurality of images are merged based on the identification mark.

[0022] The method further includes determining a spatial frequency of periodic defects in the sheet of material based on a frequency analysis of the merged image.

[0023] The merged image is elongated in a first direction that is the extension direction of the sheet of material and a second direction perpendicular to the first direction, and the step of determining the spatial frequency of the periodic defects includes performing a Fourier transform on the merged image along the first direction to generate a frequency domain image of the merged image.

[0024] The Fourier transform is a fast Fourier transform.

[0025] Performing a Fourier transform on the merged image includes dividing the merged image into a plurality of pixel arrays elongated in a first direction and arranged in a second direction, and performing a Fourier transform on each of the plurality of pixel arrays.

[0026] Performing a Fourier transform on the merged image includes generating a compressed image by adding values ​​of pixels that overlap in the second direction in the merged image, and performing a Fourier transform on the compressed image.

[0027] The method further includes determining that at least one of the first roll and the second roll corresponds to a frequency having an intensity above a threshold in the frequency domain image as the cause of the periodic defects.

[0028] The method further includes generating an alarm that includes information about the cause of the periodic defect.

[0029] According to an exemplary embodiment, a method for manufacturing a secondary battery is provided, the method including the steps of photographing multiple portions of a sheet of material to generate multiple images of the sheet of material, the sheet of material being unwound from a first roll of material by an unwinder and wound onto a second roll of material by a rewinder, generating a merged image including the multiple portions of the sheet of material based on the multiple images of the sheet of material, performing a Fourier transform on the merged image to generate a frequency domain image of the merged image, and determining a cause of periodic defects in the sheet of material based on the frequency domain image.

[0030] The frequency domain image represents the intensity-frequency distribution, and the cause of the periodic defects is determined based on a comparison of the intensity of the frequency domain image with a threshold value. [Effects of the Invention]

[0031] According to an exemplary embodiment of the present invention, in addition to detecting defects in a material sheet involved in the manufacture of a secondary battery, factors that induce periodic defects in the material sheet can be identified by performing frequency analysis on an image of the material sheet containing information about the defects, thereby enabling the factors that induce periodic defects to be promptly repaired and improving the reliability of an apparatus for manufacturing a secondary battery and a method for manufacturing a secondary battery using the same.

[0032] The effects that can be obtained from the exemplary embodiments of the present invention are not limited to the effects described above, and other effects not mentioned will be clearly derived and understood from the following description by a person having ordinary skill in the art to which the exemplary embodiments of the present disclosure belong. In other words, unintended effects accompanying the implementation of the exemplary embodiments of the present disclosure can also be derived from the exemplary embodiments of the present disclosure by a person having ordinary skill in the art. [Brief explanation of the drawings]

[0033] [Figure 1] 1 is a flowchart illustrating a method for manufacturing a secondary battery according to an exemplary embodiment. [Figure 2] 1 is a diagram illustrating an apparatus for manufacturing a secondary battery according to an exemplary embodiment; [Figure 3] 1 is a diagram illustrating a method for manufacturing a secondary battery according to an exemplary embodiment; [Figure 4] 1 is a diagram illustrating a method for manufacturing a secondary battery according to an exemplary embodiment; [Figure 5] 1 is a flowchart illustrating a method for manufacturing a secondary battery according to an exemplary embodiment. [Figure 6] 1 is a diagram illustrating a method for manufacturing a secondary battery according to an exemplary embodiment; [Figure 7] 1 is a flowchart illustrating a method for manufacturing a secondary battery according to an exemplary embodiment. [Figure 8] 1 is a diagram illustrating a method for manufacturing a secondary battery according to an exemplary embodiment; [Figure 9] 1 is a diagram illustrating an apparatus for manufacturing a secondary battery according to another exemplary embodiment; [Figure 10] 1 is a diagram illustrating an apparatus for manufacturing a secondary battery according to another exemplary embodiment; [Figure 11] 1 is a diagram illustrating an apparatus for manufacturing a secondary battery according to another exemplary embodiment; [Figure 12]1 is a diagram illustrating an apparatus for manufacturing a secondary battery according to another exemplary embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0034] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Before that, the terms and words used in the specification and claims of this application should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted as meanings and concepts that are consistent with the technical idea of ​​the present invention based on the principle that the inventor can appropriately define the concept of the term to best describe his / her invention.

[0035] Therefore, the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiment of the present invention and do not represent the entire technical idea of ​​the present invention, and there may be various equivalents and modifications that can replace them at the time of this application.

[0036] Furthermore, in the description of the present invention, if it is determined that a specific description of related publicly known structures or functions may obscure the gist of the present invention, the detailed description will be omitted.

[0037] Since the embodiments of the present invention are provided to explain the present invention in more detail to those skilled in the art, the shapes and sizes of components in the drawings may be exaggerated, omitted, or shown in a schematic manner for clearer explanation. Therefore, the sizes and proportions of each component do not completely reflect the actual sizes and proportions.

[0038] (First embodiment) FIG. 1 is a flowchart illustrating a method for manufacturing a secondary battery according to an exemplary embodiment.

[0039] FIG. 2 is a diagram illustrating an apparatus 100 for manufacturing a secondary battery according to an exemplary embodiment.

[0040] 3 and 4 are diagrams illustrating a method for manufacturing a secondary battery according to an exemplary embodiment.

[0041] 1 to 3, in P110, a plurality of images IMG1, IMG2, IMG3, IMG4, IMG5, IMG6, IMG7, IMG8, ​​and IMG9 (hereinafter referred to as IMG1 to IMG9) may be generated. The plurality of images IMG1 to IMG9 may represent different portions of the material sheet SM1 processed by the apparatus 100 for manufacturing a secondary battery. Each of the plurality of images IMG1 to IMG9 may be generated by the inspector 180 of the apparatus 100 for manufacturing a secondary battery.

[0042] According to an exemplary embodiment, an apparatus 100 for manufacturing a secondary battery may include an unwinder 110 , a plurality of rolls 120 , 130 , 150 , 160 , pressure rolls 141 , 143 , a rewinder 170 , an inspector 180 , and an analyzer 190 .

[0043] The unwinder 110 may be configured to rotate the material roll RI1 so that the material sheet SM1 is unwound from the material roll RI1. The material roll RI1 and the material sheet SM1 may include materials to be processed by a roll-to-roll process. The material roll RI1 and the material sheet SM1 may include, but are not limited to, electrodes such as positive and negative electrodes, pouch films, and separators.

[0044] The sheet of material SM1 may be moved by rotationally driving the multiple rolls 120, 130, 150, and 160. The multiple rolls 120, 130, 150, and 160 may be interposed between the unwinder 110 and the rewinder 170. The multiple rolls 120, 130, 150, and 160 may have different diameters. Some of the multiple rolls 120, 130, 150, and 160 may have different circumferences. Some of the multiple rolls 120, 130, 150, and 160 may have the same circumference and diameter.

[0045] The rolls 120, 130, 150, 160 may have synchronized circumferential speeds, i.e., at least some of the rolls 120, 130, 150, 160 may have different diameters, but the circumferential speeds of each of the rolls 120, 130, 150, 160 may be substantially the same, thereby allowing at least some of the rolls 120, 130, 150, 160 to have different rotation frequencies.

[0046] The pressure rolls 141 and 143 may be interposed between the rolls 120 and 130 and the rolls 150 and 160. The diameter of each of the pressure rolls 141 and 143 may be larger than the diameter of each of the rolls 120, 130, 150, and 160. Either one of the pressure rolls 141 and 143 may rotate, or the other may be stopped. The pressure rolls 141 and 143 may rotate in the opposite direction to each other or in the same direction to each other.

[0047] Each of the pressure rolls 141 and 143 can apply pressure to the material sheet SM1 transmitted by the rotation of the rolls 120 and 130. This allows the material sheet SM1 to undergo either a flattening process or a roll pressing process.

[0048] The material sheet SM1 is stored in a rolled state for a certain period of time, and therefore contains curl. Such curl can cause reliability problems in processes for manufacturing secondary batteries, such as packaging an electrode assembly using a pouch film. The flattening process for the material sheet SM1 can remove or reduce the curl formed on the material sheet SM1, thereby improving the reliability of secondary battery manufacturing.

[0049] Here, the pouch film PF may include an inner resin layer, a metal layer, and an outer resin layer. The inner resin layer may have thermal adhesive properties, which allows the pouch film PF to be sealed. The inner resin layer may include, for example, a polyolefin-based material. The metal layer may include any one of an alloy of iron, carbon, chromium, and manganese, an alloy of iron, chromium, and nickel, and aluminum.

[0050] Pouch film PF may be used to manufacture pouch-type battery cells. A battery cell is the basic unit of a lithium-ion battery, i.e., a secondary battery. A battery cell includes an electrode assembly, an electrolyte, and a case. Battery cells are classified into lithium-ion batteries, lithium-ion polymer batteries, and lithium polymer batteries depending on the configuration of the electrode assembly and electrolyte. Lithium-ion polymer batteries are easy to manufacture and have little risk of electrolyte leakage, and are therefore gaining market share in secondary batteries.

[0051] The pouch-type battery cell may include an electrode assembly and a pouch case that houses the electrode assembly. The pouch case may be provided by a forming process and a sealing process of a pouch film PF.

[0052] The thickness of the positive electrode plate may be in the range of about 3 μm to about 500 μm. The positive electrode plate may not induce chemical changes in the final secondary battery and may have high conductivity. The positive electrode plate may include, for example, stainless steel, nickel, titanium, calcined carbon, and aluminum. The positive electrode plate may also include stainless steel surface-treated with carbon, nickel, titanium, silver, or the like. The surface of the positive electrode plate may include a micro-textured structure to enhance the adhesive strength of the active material. The positive electrode plate may have the shape of a film, sheet, foil, net, porous material, foam, nonwoven fabric, or the like.

[0053] The thickness of the negative electrode plate may be in the range of about 3 μm to about 500 μm. The negative electrode plate may not induce chemical changes in the final secondary battery and may have high conductivity. The negative electrode plate may include copper, stainless steel, aluminum, nickel, titanium, calcined carbon, and aluminum-cadmium alloy. The negative electrode plate may include stainless steel surface-treated with carbon, nickel, titanium, silver, or the like. The surface of the negative electrode plate may include a micro-textured structure to enhance the adhesion of the active material. The negative electrode plate may have the form of a film, sheet, foil, net, porous material, foam, nonwoven fabric, or the like.

[0054] The positive electrode active material is a material capable of undergoing an electrochemical reaction. The positive electrode active material may be a lithium transition metal oxide. Examples of the positive electrode active material include layered compounds such as lithium cobalt oxide (LiCoO2) and lithium nickel oxide (LiNiO2) substituted with one or more transition metals; lithium manganese oxide substituted with one or more transition metals; and lithium manganese oxides with the chemical formula LiNi 1-y M y Lithium nickel-based oxide represented by LiO2 (wherein M is any one of Co, Mn, Al, Cu, Fe, Mg, B, Cr, Zn, and Ga, and 0.01≦y≦0.7); 1+z Ni 1 / 3 Co 1 / 3 Mn 1 / 3 O2, Li 1+z Ni 0.4 Mn 0.4 Co 0.2 Li like O2 1+z Ni b Mn c Co 1-(b+c+d) M d O (2-e) A e (wherein -0.5≦z≦0.5, 0.1≦b≦0.8, 0.1≦c≦0.8, 0≦d≦0.2, 0≦e≦0.2, b+c+d<1, M is any one of Al, Mg, Cr, Ti, Si, and Y, and A is any one of F, P, and Cl); lithium nickel cobalt manganese composite oxide represented by the chemical formula Li1+x M 1-y M’ y PO 4-z X z (Here, M is a transition metal, more specifically, any one of Fe, Mn, Co, and Ni; M’ is any one of Al, Mg, and Ti; X is any one of F, S, and N; -0.5 ≦ x ≦ +0.5, 0 ≦ y ≦ 0.5, and 0 ≦ z ≦ 0.1.) It may contain olivine-type lithium metal phosphate represented by

[0055] The negative electrode active material may contain carbon such as non-graphitized carbon and graphite-based carbon. For example, the negative electrode active material is Li x Fe2O3 (0 ≦ x ≦ 1), Li x WO2 (0 ≦ x ≦ 1), Sn x Me 1-x Me’ y O z (Here, Me is any one of Mn, Fe, Pb, and Ge; Me’ is any one of Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, and halogen; 0 < x ≦ 1; 1 ≦ y ≦ 3; 1 ≦ z ≦ 8.) It may contain metal composite oxides such as. The negative electrode active material may contain, for example, lithium metal; lithium alloy; silicon-based alloy; tin-based alloy. The negative electrode active material may contain metal oxides such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, Bi2O5. The negative electrode active material may contain, for example, conductive polymers such as polyacetylene; and Li-Co-Ni-based materials, etc.

[0056] The roll press process is a process in which pressure is applied to an electrode plate coated with an active material to flatten the surface of the secondary battery electrode and make it lighter and thinner. The roll press process can strengthen the bonding force between the surface of the electrode plate and the active material. The strengthened bonding force between the surface of the electrode plate and the active material can promote the movement of lithium ions in the electrode, thereby improving the output and performance of the final secondary battery.

[0057] The sheet of material SM1 delivered by the rolls 150, 160 may be wound up by a rewinder 170. The winding of the sheet of material SM1 may provide a roll of material RO1.

[0058] Inspector 180 may be configured to inspect the appearance of sheet of material SM1. Inspector 180 may be configured to inspect the appearance of sheet of material SM1 in a non-contact manner, such as an image-based vision inspection device. Inspector 180 may include one or more cameras. Inspector 180 may be configured to determine defects in multiple portions of sheet of material SM1, such as foreign matter, dirt, surface defects, scratches, dents, perforations, protrusions, depressions, nucleated scratches, and non-nucleated scratches, based on multiple images IMG1-IMG9 captured by the one or more cameras. Inspector 180 may be configured to determine the uniformity of the distribution of a coating layer containing an active material and a binder. Inspector 180 may be configured to determine the locations of defects D1, D2, and D3 in multiple images IMG1-IMG9 based on two-dimensional light intensity profiles (or two-dimensional reflectance profiles) of the multiple images IMG1-IMG9.

[0059] Analyzer 190 may be configured to analyze the inspection results of inspector 180. More specifically, analyzer 190 may generate a merged image MIMG in P120, perform frequency analysis on the merged image MIMG in P130, determine spatial frequencies of periodic defects in P140, and determine causes of the periodic defects in P150.

[0060] The analyzer 190 may be a computing device such as a workstation computer, desktop computer, laptop computer, or tablet computer. The analyzer 190 may be configured as separate hardware or as separate software included in a single piece of hardware. The analyzer 190 may be a simple controller, a complex processor such as a microprocessor, a central processing unit (CPU), a graphics processing unit (GPU), a software-configured processor, dedicated hardware, or firmware. The analyzer 190 may be implemented, for example, by a general-purpose computer or application-specific hardware such as a digital signal processor (DSP), a field programmable gate array (FPGA), or an application-specific integrated circuit (ASIC).

[0061] In some embodiments, the operations of analyzer 190, described below, may be implemented as instructions stored on a machine-readable medium, which may be read and executed by one or more processors. Here, a machine-readable medium may include any mechanism for storing and / or transmitting information in a form readable by a machine (e.g., a computing device). For example, a machine-readable medium may include read-only memory (ROM), random access memory (RAM), magnetic disk storage media, optical storage media, flash memory devices, electrical, optical, acoustical, or other forms of radio signals (e.g., carrier waves, infrared signals, digital signals, etc.), and any other signals.

[0062] Analyzer 190 may be configured with firmware, software, routines, and instructions to perform the operations described for analyzer 190 or any of the steps described below, however, this is for convenience of explanation and it should be understood that the operations of analyzer 190 described above may be caused by a computing device, processor, controller, or other device executing firmware, software, routines, instructions, and the like.

[0063] Subsequently, a merged image MIMG may be generated in P120. The analyzer 190 may be configured to merge the plurality of images IMG1-IMG9 to generate the merged image MIMG. Each of the plurality of images IMG1-IMG9 may extend in an X direction and a Y direction. The X direction may be the extension direction of the sheet of material SM1. The X direction may be the direction of movement of the sheet of material SM1. The Y direction may be substantially perpendicular to the X direction. The Y direction may be the width direction of the sheet of material SM1. Each of the plurality of images IMG1-IMG9 may correspond to a field of view of the inspector 180 and thereby include a portion of the sheet of material SM1. The analyzer 190 may stitch the plurality of images IMG1-IMG9 in the X direction to provide the merged image MIMG.

[0064] Each of the plurality of images IMG1-IMG9 may represent a defect D1, D2, D3 in the sheet of material SM1, such that the merged image MIMG may also include defects D1, D2, D3.

[0065] Within the merged image MIMG, each of the defects D1, D2, and D3 may be repeated periodically. Within the merged image MIMG, each of the defects D1, D2, and D3 may be repeated with a predetermined spatial period in the X direction. As such, each of the defects D1, D2, and D3 may be referred to as a periodic defect.

[0066] For example, defect D1 may be repeated with a spatial period T1, defect D2 may be repeated with a spatial period T2, and defect D3 may be repeated with a spatial period T3. The spatial periods T1, T2, and T3 may be different from one another. The spatial period T1 may be shorter than the spatial period T2. The spatial period T2 may be shorter than the spatial period T3.

[0067] Each of the spatial periods T1, T2, and T3 may correspond to a spatial frequency defined as its reciprocal. The units of the spatial periods T1, T2, and T3 may be m, or the spatial periods T1, T2, and T3 may be standardized dimensionless quantities. Thus, the units of the spatial frequencies may be 1 / m, or the spatial frequencies may be standardized dimensionless quantities. For example, if the spatial period T1 is approximately 1 / 2 [m], the spatial period T2 is approximately 2 [m], and the spatial period T3 is approximately 4 [m], the spatial frequency corresponding to the spatial period T1 is approximately 2 [m]. -1 ], and the spatial frequency corresponding to the spatial period T2 is approximately 1 / 2[m -1 ], and the spatial frequency corresponding to the spatial period T3 is approximately 1 / 4 [m -1 ] may also be used.

[0068] 1-4, frequency analysis may be performed on the merged image MIMG in P130. The merged image MIMG may include multiple pixels in the X and Y directions. Defects D1, D2, and D3 may be represented by coordinates based on pixel locations in the merged image MIMG. Here, the pixel locations may be represented by a local coordinate system specific to each of the multiple images IMG1-IMG9, or by a global coordinate system common to the entire merged image MIMG.

[0069] In the merged image MIMG, the value of a pixel having defects D1, D2, D3 may be, for example, 1, and the value of a pixel not having defects D1, D2, D3 may be, for example, 0. The pixel values ​​are non-limiting examples, and the pixels may have any value to distinguish between the presence and absence of defects D1, D2, D3.

[0070] In the present example, a compressed image CIMG may be generated for frequency analysis of the merged image MIMG. The compressed image CIMG may be generated by adding values ​​of overlapping pixels in the Y direction. Thus, the compressed image CIMG may contain the same number of pixels as the merged image MIMG in the X direction, or may contain fewer pixels (e.g., one) than the merged image MIMG in the Y direction. The analyzer 190 may be configured to perform a Fourier transform in the X direction on the compressed image CIMG.

[0071] In Figure 3, because there are no overlapping defects in the Y direction, the value of the pixel overlapping each of defects D1, D2, and D3 may be 1. Unlike what is shown in Figure 3, if there is an additional defect in merged image MIMG that overlaps with a portion of defects D1, D2, and D3, the value of the corresponding pixel in condensed image CIMG may be 2 or greater.

[0072] The Fourier transform of the compressed image CIMG may be a discrete Fourier transform, such as a fast Fourier transform. The Fourier transform of the compressed image CIMG may be a short time Fourier transform. The Fourier transform of P130 may provide an intensity-spatial frequency graph such as that shown in FIG. 4. An intensity-spatial frequency graph such as that shown in FIG. 4 may be referred to as a frequency domain image.

[0073] Next, in P140, spatial frequencies of the periodic defects may be determined. The spatial frequencies of the periodic defects may be spatial frequency values ​​that exceed a threshold intensity in the frequency domain image. For example, in FIG. 4, the intensities corresponding to spatial frequencies f1, f2, and f3 exceed the threshold CP, so each of spatial frequencies f1, f2, and f3 may be a spatial frequency of a periodic defect.

[0074] Signals having an intensity below the threshold value C may be treated as noise in determining the spatial frequency of the periodic defects, and signals having values ​​below the lower frequency limit fc1 or above the upper frequency limit fc2 may be treated as noise due to the absence of elements of the apparatus 100 for manufacturing secondary batteries having a corresponding spatial frequency.

[0075] Subsequently, in P150, a cause of the periodic defects may be determined. Determining the cause of the periodic defects may include calculating spatial periods T1, T2, and T3 based on the spatial frequencies f1, f2, and f3. According to an exemplary embodiment, the spatial periods T1, T2, and T3 may be the reciprocals of the spatial frequencies f1, f2, and f3.

[0076] Determining the cause of the periodic defects may include determining which of the rolls 120, 130, 150, 160 and pressure rolls 141, 143 have periods similar to the spatial periods T1, T2, and T3. Here, "similar periods" refers to periods within a range determined from the spatial periods T1, T2, and T3 calculated from the spatial frequencies f1, f2, and f3. The range determined from the spatial periods T1, T2, and T3 includes systematic errors, negligence errors, and accidental errors that inevitably occur in calculating the spatial periods T1, T2, and T3. The range determined from each of the spatial periods T1, T2, and T3 includes the spatial periods T1, T2, and T3 and may include upper limits greater than the spatial periods T1, T2, and T3, respectively, and lower limits less than the spatial periods T1, T2, and T3, respectively.

[0077] According to an exemplary embodiment, the spatial periods T1, T2, and T3 may correspond to characteristic lengths of the plurality of rolls 120, 130, 150, and 160 and the pressure rolls 141 and 143. According to an exemplary embodiment, the spatial periods T1, T2, and T3 may be the same as the circumference of some of the plurality of rolls 120, 130, 150, and 160 and the pressure rolls 141 and 143. Additionally, multiples (e.g., 2x, 3x, 4x, etc.) of the spatial periods T1, T2, and T3 may be the same as the circumference of some of the plurality of rolls 120, 130, 150, and 160 and the pressure rolls 141 and 143.

[0078] Therefore, elements (i.e., the multiple rolls 120, 130, 150, 160 and pressure rolls 141, 143) having a characteristic length (e.g., circumference) within a set range from the spatial periods T1, T2, T3, or having a characteristic length (e.g., circumference) within a set range from a multiple (e.g., 2x, 3x, 4x, etc.) of the spatial periods T1, T2, T3 may be determined to be the cause of the periodic defect.

[0079] In the roll-to-roll process, if a defect factor occurs in the multiple rolls 120, 130, 150, 160 and the pressure rolls 141, 143, the defect factor induces repeated periodic defects D1, D2, D3 in the material sheet SM1. Therefore, prompt detection and repair of the periodic defects D1, D2, D3 is an essential element for improving the yield of secondary batteries.

[0080] The apparatus 100 for manufacturing a secondary battery according to the exemplary embodiment and the method for manufacturing a secondary battery using the same may determine in real time the occurrence of periodic defects D1, D2, and D3 and factors of the apparatus 100 for manufacturing a secondary battery that cause the periodic defects D1, D2, and D3. In particular, even in the case of defects with a long occurrence period (i.e., a long characteristic length), such as defects induced by the pressure rolls 141 and 143, the occurrence of periodic defects and the factors that cause them may be determined. This may improve the yield and reliability of secondary battery manufacturing.

[0081] An alarm may then be generated. The alarm may include information about the occurrence and cause of the periodic defect (i.e., the element of the apparatus 100 for manufacturing secondary batteries that triggers the periodic cause). The alarm can notify an operator of the occurrence and cause of the periodic defect. The analyzer 190 may be configured to generate a signal to generate an alarm to notify an operator when the cause of the periodic defect is determined in P150. Furthermore, the analyzer 190 may generate an interrupt signal to stop operation of the element of the apparatus 100 for manufacturing secondary batteries. The interrupt signal may be transmitted from the analyzer 190 to a controller (e.g., a programmable logic controller (PLC)) configured to control the element of the apparatus 100 for manufacturing secondary batteries. This can prevent additional defects from occurring in the sheet of material SM1 due to the cause of the periodic defect.

[0082] (Second embodiment) FIG. 5 is a flowchart illustrating a method for manufacturing a secondary battery according to an exemplary embodiment.

[0083] FIG. 6 is a diagram illustrating a method for manufacturing a secondary battery according to an exemplary embodiment.

[0084] The method of Fig. 5 is substantially the same as that described with reference to Figs. 1 to 4, except that frequency analysis is performed on the merged image at P131. The method of Fig. 5 may be performed by the apparatus 100 for manufacturing a secondary battery of Fig. 2.

[0085] 2, 5, and 6, the frequency analysis for the merged image of P131 may be performed directly on the merged image MIMG without generating a compressed image CIMG (see FIG. 3). According to an exemplary embodiment, the analyzer 190 may divide the merged image MIMG into a plurality of pixel arrays PA1, PA2, ..., PAN-1, PAN. According to an exemplary embodiment, the analyzer 190 may perform a Fourier transform on each of the plurality of pixel arrays PA1, PA2, ..., PAN-1, PAN of the merged image MIMG.

[0086] Each of the multiple pixel arrays PA1, PA2, ..., PAN-1, PAN may include the same number of pixels as the merged image MIMG in the X direction. Each of the multiple pixel arrays PA1, PA2, ..., PAN-1, PAN may include fewer pixels (e.g., one) than the merged image MIMG in the Y direction. Each of the multiple pixel arrays PA1, PA2, ..., PAN-1, PAN may be arranged in the Y direction.

[0087] Thus, in P150, determining the cause of the periodic defect may determine the Y-direction coordinate of the cause in addition to determining the cause of the periodic defect among the plurality of rolls 120, 130, 150, 160 and the pressure rolls 141, 143. This allows the plurality of rolls 120, 130, 150, 160 and the pressure rolls 141, 143 to be repaired quickly.

[0088] (Third embodiment) FIG. 7 is a flowchart illustrating a method for manufacturing a secondary battery according to an exemplary embodiment.

[0089] FIG. 8 is a diagram illustrating a method for manufacturing a secondary battery according to an exemplary embodiment.

[0090] The method of Fig. 7 is substantially the same as that described with reference to Figs. 1 to 4, except that frequency analysis is performed on the merged image in P121. The method of Fig. 7 may be performed by the apparatus 100 for manufacturing a secondary battery of Fig. 2.

[0091] Referring to Figures 2, 7 and 8, multiple images IMG1', IMG2', IMG3', IMG4', IMG5', IMG6', IMG7', IMG8', IMG9' (hereinafter referred to as IMG1' to IMG9') may include overlapping areas OV1, OV2, OV3, OV4, OV5, OV6, OV7, OV8 (hereinafter referred to as OV1 to OV8). More specifically, overlap area OV1 may be included in each of images IMG1' and IMG2', overlap area OV2 may be included in each of images IMG2' and IMG3', overlap area OV3 may be included in each of images IMG3' and IMG4', overlap area OV4 may be included in each of images IMG4' and IMG5', overlap area OV5 may be included in each of images IMG5' and IMG6', overlap area OV6 may be included in each of images IMG6' and IMG7', overlap area OV7 may be included in each of images IMG7' and IMG8', and overlap area OV8 may be included in each of images IMG8' and IMG9'.

[0092] The capture rate at which multiple images IMG1'-IMG9' are generated by inspector 180 may be synchronized to the transport speed of sheet of material SM1 so that overlap regions OV1-OV8 are minimized. If uncorrected, overlap regions OV1-OV8 can distort the spatial periodicity of defects D1, D2, and D3.

[0093] According to an exemplary embodiment, the plurality of images IMG1′-IMG9′ may further include, in addition to portions of the sheet of material SM1, a drive shaft DS of any one of the plurality of rolls 120, 130, 150, 160 and pressure rolls 141, 143. The drive shaft may include an identification mark IM, such that the plurality of images IMG1′-IMG9′ may include the identification mark IM. Analyzer 190 may be configured to determine overlap regions OV1-OV8 based on the size and shape of the identification mark IM appearing in the plurality of images IMG1′-IMG9′.

[0094] According to an exemplary embodiment, in P121, the analyzer 190 may be configured to prevent overlapping of the overlapping regions OV1 to OV8 when generating the merged image MIMG, thereby preventing distortion of the spatial frequency of periodic defects due to the overlapping regions OV1 to OV8 and improving the reliability of the apparatus 100 for manufacturing a secondary battery and the method for manufacturing a secondary battery using the same.

[0095] (Fourth embodiment) FIG. 9 is a diagram illustrating an apparatus 200 for manufacturing a secondary battery according to another exemplary embodiment.

[0096] 9, the apparatus 200 for manufacturing a secondary battery may be a coater apparatus. The apparatus 200 for manufacturing a secondary battery may include an unwinder 210, a plurality of rolls 220 and 240, die coaters 231 and 233, a rewinder 250, an inspector 260, and an analyzer 270.

[0097] The unwinder 210 may be configured to rotate the material roll RI2 so that the material sheet SM2 is unwound from the material roll RI2. The material roll RI2 and the material sheet SM2 may include a positive electrode plate or a negative electrode plate.

[0098] The material sheet SM2 may be moved by rotationally driving the multiple rolls 220, 240. The multiple rolls 220, 240 may be interposed between the unwinder 210 and the rewinder 250. The multiple rolls 220, 240 may have different diameters. The multiple rolls 220, 240 may have different circumferences. Some of the multiple rolls 220, 240 may have the same circumference and diameter.

[0099] The rolls 220, 240 may have synchronized peripheral speeds, i.e., at least some of the rolls 220, 240 may have different diameters, but the peripheral speeds of the rolls 220, 240 may be substantially the same, so that at least some of the rolls 220, 240 may have different rotational speeds from one another.

[0100] The die coaters 231 and 233 may be interposed between the roll 220 and the roll 240. Each of the die coaters 231 and 233 may be configured to discharge an electrode slurry. The electrode slurry discharged by the die coaters 231 and 233 may be coated onto the material sheet SM2.

[0101] The sheet of material SM2 transmitted by the roll 240 may be wound up by the rewinder 250. The winding of the sheet of material SM2 may provide a roll of material RO2.

[0102] Inspector 260 may be configured to inspect the appearance of sheet of material SM2. Inspector 260 and analyzer 270 may be substantially similar to inspector 180 and analyzer 190, respectively, of Figure 2. According to an exemplary embodiment, analyzer 270 may be configured to perform the methods of Figures 1, 5, and 7.

[0103] (Fifth embodiment) FIG. 10 is a diagram illustrating an apparatus 300 for manufacturing a secondary battery according to another exemplary embodiment.

[0104] Referring to FIG. 10, an apparatus 300 for manufacturing a secondary battery may be a slitting apparatus.

[0105] According to an exemplary embodiment, an apparatus 300 for manufacturing a secondary battery may include an unwinder 310 , a plurality of rolls 320 , 330 , 340 , 360 , a slitter 350 , a rewinder 370 , an inspector 380 , and an analyzer 390 .

[0106] The unwinder 310 may be configured to rotate the material roll RI3 such that the material sheet SM3 is unwound from the material roll RI3. The material roll RI3 and the material sheet SM3 may include a positive electrode plate or a negative electrode plate.

[0107] The sheet of material SM3 may be moved by rotationally driving the multiple rolls 320, 330, 340, and 360. The multiple rolls 320, 330, 340, and 360 may be interposed between the unwinder 310 and the rewinder 370. The multiple rolls 320, 330, 340, and 360 may have different diameters. The multiple rolls 320, 330, 340, and 360 may have different circumferences. Some of the multiple rolls 320, 330, 340, and 360 may have the same circumference and diameter.

[0108] The rolls 320, 330, 340, 360 may have synchronized peripheral speeds, i.e., at least some of the rolls 320, 330, 340, 360 may have different diameters, but the peripheral speeds of each of the rolls 320, 330, 340, 360 may be substantially the same, so that at least some of the rolls 320, 330, 340, 360 may have different rotational speeds from one another.

[0109] Slitter 350 may be interposed between rolls 320, 330, 340 and roll 360. Slitter 350 may cut sheet of material SM3 to provide multiple sheets of material SM3'. Each of the multiple sheets of material SM3' may have a width smaller than that of sheet of material SM3. For convenience of illustration, sheet of material SM3 is shown as being separated into two sheets of material SM3', but this does not in any way limit the technical concept of the present invention. Based on what is described herein, one of ordinary skill in the art can easily arrive at an embodiment in which sheet of material SM3 is separated into three or more sheets of material SM3'.

[0110] The sheet of material SM3' transmitted by the roll 360 may be wound up by a rewinder 370. The winding of the sheet of material SM3' may provide a roll of material RO3.

[0111] Inspectors 380 may be configured to inspect the appearance of sheet of material SM3'. Each of inspectors 380 may be substantially similar to inspector 180 of Figure 2, and analyzer 390 may be substantially similar to analyzer 190 of Figure 2. According to an exemplary embodiment, analyzer 390 may be configured to perform the methods of Figures 1, 5, and 7.

[0112] (Sixth embodiment) FIG. 11 is a diagram illustrating an apparatus 400 for manufacturing a secondary battery according to another exemplary embodiment.

[0113] According to an exemplary embodiment, the apparatus 400 for manufacturing secondary batteries may include a drive wheel 410 , a conveyor belt 420 , a notching device 430 , inspectors 441 , 443 , and an analyzer 450 .

[0114] Conveyor belt 420 may transport sheet of material SM4 by rotation of drive wheel 410. Sheet of material SM4 may be one of a separator membrane, a pouch film, and an electrode.

[0115] The notching device 430 may be disposed on the conveyor belt 420. According to an exemplary embodiment, the notching device 430 may be, but is not limited to, a laser notcher configured to irradiate the material sheet SM4 with a laser. The notching device 430 may also include a punching knife. The notching device 430 may remove the uncoated portions of the material sheet SM4 except for the portions for joining the tabs. Separated material SM4' may be provided by the notching device 430 processing the material sheet SM4. The separated material SM4' may have a size and shape for use in an electrode of a battery cell.

[0116] According to an exemplary embodiment, inspector 441 may be configured to inspect the appearance of sheet of material SM4. Inspector 443 may be configured to inspect separated material SM4'. Each of inspectors 441, 443 may be substantially similar to inspector 180 of FIG. 2, and analyzer 450 may be substantially similar to analyzer 190 of FIG. 2. According to an exemplary embodiment, analyzer 450 may be configured to perform the methods of FIGS. 1, 5, and 7.

[0117] Seventh embodiment FIG. 12 is a diagram illustrating an apparatus 500 for manufacturing a secondary battery according to another exemplary embodiment.

[0118] According to an exemplary embodiment, the apparatus 500 for manufacturing secondary batteries may include a drive wheel 510 , a conveyor belt 520 , an inspector 530 , and an analyzer 540 .

[0119] The conveyor belt 520 may transport the material MM by rotation of the drive wheel 510. The material MM may be a secondary battery cell.

[0120] A battery cell is the basic unit of a lithium-ion battery, i.e., a secondary battery, and includes an electrode assembly, an electrolyte, and a case.

[0121] Depending on the shape of the battery case, battery cells are classified into cylindrical batteries in which the electrode assembly is housed in a cylindrical metal can, prismatic batteries in which the electrode assembly is housed in a prismatic metal can, and pouch batteries in which the electrode assembly is housed in a pouch case made of aluminum laminate sheet.

[0122] The electrode assembly housed in the battery case includes a positive electrode, a negative electrode, and a separator interposed between the positive and negative electrodes. Electrode assemblies are classified into jelly roll and stack types depending on the assembly form. The jelly roll type is a rolled-up assembly of a positive electrode, a negative electrode, and a separator interposed between them. The stack type is a stacked assembly of multiple positive electrodes, multiple negative electrodes, and multiple separators interposed between them.

[0123] The positive electrode may include a positive electrode current collector and a positive electrode active material, and the negative electrode may include a negative electrode current collector and a negative electrode active material.

[0124] According to an exemplary embodiment, the apparatus 500 for manufacturing a secondary battery may be configured to perform a battery assembly process. According to an exemplary embodiment, the apparatus 500 for manufacturing a secondary battery may be configured to perform any one of an electrode stacking process, a pouch cutting process, a pouch forming process, an electrolyte injection process, an activation process, an aging process, and a degassing process.

[0125] The electrode stacking process may provide an electrode assembly by stacking a positive electrode, a negative electrode, and a separator. The pouch cutting process may cut a pouch film to a specified size. The pouch forming process may form the pouch film into a shape suitable for housing the electrode assembly. The electrolyte injection process may inject an electrolyte into the battery case. The activation process may perform an initial charge and discharge on the battery cell. In the activation process, an SEI (Solid Electrolyte Interphase) layer may be formed. The aging process may store the battery in a controlled temperature and humidity environment for a predetermined time (e.g., 30 minutes to 3 hours). The degassing process may cut out air pockets and remove unwanted gas after the electrolyte injection.

[0126] According to an exemplary embodiment, inspector 530 may be configured to inspect the appearance of material MM. Inspector 530 may be substantially the same as inspector 180 of Figure 2, and analyzer 540 may be substantially the same as analyzer 190 of Figure 2. According to an exemplary embodiment, analyzer 540 may be configured to perform the methods of Figures 1, 5, and 7.

[0127] The present invention has been described in more detail above through the drawings, embodiments, etc. However, the configurations described in the drawings or embodiments in this specification are merely one embodiment of the present invention and do not fully represent the technical ideas of the present invention, and therefore, various equivalents and modifications may exist that can replace them at the time of this application.

Claims

1. a first roll and a second roll configured to move a sheet of material; an inspector configured to generate a plurality of images by photographing a plurality of portions of the sheet of material, some of the plurality of images including periodic defects; and an analyzer configured to generate a merged image including the plurality of portions of the sheet of material based on the plurality of images of the sheet of material; The apparatus for manufacturing a secondary battery, wherein the analyzer is configured to determine a spatial frequency of the periodic defects in the sheet of material based on the merged image.

2. The apparatus for manufacturing a secondary battery according to claim 1 , wherein the merged image is generated by merging the plurality of images along a first direction that is an extension direction of the material sheet.

3. each of the plurality of images includes an identification mark of one of the first roll and the second roll; The apparatus for manufacturing a secondary battery according to claim 1 or 2, wherein the analyzer merges the plurality of images based on the identification mark.

4. The apparatus for manufacturing a secondary battery according to claim 3 , wherein the analyzer prevents overlapping of the portions of the sheet of material in the merged image based on the identification mark.

5. the merged image is elongated in a first direction that is the elongation direction of the sheet of material and in a second direction perpendicular to the first direction; 3. The apparatus for manufacturing a secondary battery of claim 1, wherein determining the spatial frequency of the periodic defects comprises performing a Fourier transform on the merged image in the first direction to generate a frequency domain image of the merged image.

6. The apparatus for manufacturing a secondary battery according to claim 5 , wherein the Fourier transform is a discrete Fourier transform.

7. The apparatus for manufacturing a secondary battery according to claim 5 , wherein the Fourier transform is a fast Fourier transform.

8. 6. The apparatus for manufacturing a secondary battery of claim 5, wherein the analyzer is configured to determine that at least one of the first roll and the second roll corresponds to a frequency having an intensity above a threshold in the frequency domain image.

9. performing the Fourier transform on the merged image Dividing the merged image into a plurality of pixel arrays elongated in the first direction and arranged in the second direction; and performing a Fourier transform on each of the plurality of pixel arrays.

10. performing a Fourier transform on the merged image; generating a compressed image by adding values ​​of pixels that overlap in the second direction in the merged image; and performing a Fourier transform on the compressed image.

11. The apparatus for manufacturing a secondary battery according to claim 1 or 2, further comprising a pressure roll configured to pressurize the material sheet.

12. The apparatus for manufacturing a secondary battery according to claim 1 or 2, further comprising a die coater configured to coat the material sheet with an electrode slurry.

13. a conveyor belt configured to move the sheet of material; an inspector configured to generate a plurality of images by photographing a plurality of portions of the sheet of material; an analyzer configured to generate a merged image including the plurality of portions of the sheet of material based on the plurality of images of the sheet of material; The apparatus for manufacturing a secondary battery, wherein the analyzer is configured to analyze a spatial frequency of periodic defects in the sheet of material based on the merged image.

14. The apparatus for manufacturing a secondary battery according to claim 13 , further comprising a laser notcher configured to irradiate the sheet of material with a laser.

15. photographing a plurality of portions of a sheet of material to generate a plurality of images of the sheet of material, the sheet of material being moved by a first roll and a second roll; generating a merged image including the plurality of portions of the sheet of material based on the plurality of images of the sheet of material; and performing frequency analysis on the merged image.

16. each of the plurality of images includes an identification mark of one of the first roll and the second roll; The method for manufacturing a secondary battery according to claim 15 , wherein the plurality of images are merged based on the identification mark.

17. 17. The method for manufacturing a secondary battery according to claim 15 or 16, further comprising the step of determining a spatial frequency of periodic defects in the sheet of material based on the frequency analysis of the merged image.

18. the merged image is elongated in a first direction that is the elongation direction of the sheet of material and in a second direction perpendicular to the first direction; 20. The method for manufacturing a secondary battery of claim 17, wherein determining the spatial frequency of the periodic defects includes performing a Fourier transform on the merged image in the first direction to generate a frequency domain image of the merged image.

19. 20. The method for manufacturing a secondary battery according to claim 18, wherein the Fourier transform is a fast Fourier transform.

20. performing the Fourier transform on the merged image Dividing the merged image into a plurality of pixel arrays elongated in the first direction and arranged in the second direction; and performing a Fourier transform on each of the plurality of pixel arrays.

21. performing a Fourier transform on the merged image; generating a compressed image by adding values ​​of pixels that overlap in the second direction in the merged image; and performing a Fourier transform on the compressed image.

22. 20. The method for manufacturing a secondary battery of claim 18, further comprising determining that at least one of the first roll and the second roll corresponds to a frequency having an intensity above a threshold in the frequency domain image as the cause of the periodic defects.

23. The method of manufacturing a secondary battery according to claim 22, further comprising the step of generating an alarm containing information regarding the cause of the periodic defect.

24. photographing a plurality of portions of a sheet of material to generate a plurality of images of the sheet of material, the sheet of material being unwound from a first roll of material by an unwinder and rewound onto a second roll of material by a rewinder; generating a merged image including the plurality of portions of the sheet of material based on the plurality of images of the sheet of material; performing a Fourier transform on the merged image to generate a frequency domain image of the merged image; and determining a cause of periodic defects in the sheet of material based on the frequency domain image.

25. the frequency domain image represents an intensity frequency distribution; 25. The method of manufacturing a secondary battery of claim 24, wherein the cause of the periodic defects is determined based on a comparison of the intensity of the frequency domain image to a threshold.

Images