Foreign Substance Detection Device and Foreign Substance Detection Method for Electrode Active Material

Abstract

The disclosed invention provides a foreign matter detection device including: a suspension tank containing a suspension in which an electrode active material is uniformly dispersed; a filter having a predetermined pore size and filtering the suspension transferred from the suspension tank to collect foreign matter in the electrode active material; and an analyzer analyzing the filter on which the foreign matter is collected to detect at least one of the type of the foreign matter, the number of the foreign matter, the shape of the foreign matter, and the size of the foreign matter. The disclosed invention also provides a method for detecting foreign matter in an electrode active material.

Description

Technical Field

[0001] The present invention relates to a foreign substance detection device and a foreign substance detection method for an electrode active material.

[0002] More specifically, the present invention relates to a foreign substance detection device and a foreign substance detection method having excellent foreign substance detection rates for foreign substances contained in an electrode active material.

[0003] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0026212 filed on February 27, 2023, and all contents disclosed in the literature of the Korean patent application are included as part of this specification.

Background Art

[0004] A secondary battery is manufactured by accommodating an electrode assembly in a battery case and injecting an electrolyte. The electrode assembly has a structure in which a separator is interposed between a positive electrode and a negative electrode and is laminated.

[0005] Electrodes such as a positive electrode and a negative electrode are manufactured by coating a current collector with a predetermined active material slurry. The electrode active material may contain a small amount of foreign substances. Foreign substances contained in the electrode deteriorate the characteristics and quality of a secondary battery cell manufactured including the electrode, such as low voltage defects.

[0006] Therefore, it is important to detect the types, numbers, shapes, and sizes of foreign substances in the electrode active material to grasp which foreign substances affect the characteristics of the secondary battery. For this purpose, it is necessary to collect and detect foreign substances contained in the electrode active material with a high probability. Also, it is preferable to quickly inspect as much electrode active material as possible to match the production speed of mass production equipment.

[0007] As one of the conventional methods for detecting foreign substances in active materials, there is a method of filtering electrode active material powder by applying air pressure above and below a metal filter. The active material powder with a size smaller than the foreign substance passes through the metal filter, and the foreign substance is collected on the surface of the filter. Since the foreign substance spreads and disperses over the entire filter area by air pressure, a filter with a large area is required for foreign substance collection. Since foreign substances are sparsely collected on the large-area filter, the tape is repeatedly adhered to and detached from the filter several times to increase the collection density. The tape with the foreign substance attached can be analyzed with, for example, an XRF analyzer to identify the type of foreign substance and the like.

[0008] However, in such a method, a large amount of foreign substances are lost during the process of adhering and detaching the tape, and the amount and number of foreign substances in the active material cannot be accurately grasped. In addition, since a metal filter is used, foreign substances with weak magnetism or paramagnetism may not be properly adsorbed on the filter due to their magnetic properties. Therefore, the detection rate (recovery rate) of foreign substances in the electrode active material is very low, and it has been extremely difficult to apply it to actual foreign substance detection.

[0009] To improve such problems, there is a method of sampling electrode active material powder containing foreign substances on a film and analyzing it with an analyzer. However, in this case, since foreign substances that are spread and distributed in the electrode active material are detected together with the active material, it has been difficult to inspect a large amount of active material. Only a small sample size of about 10 mg level could be inspected. To perform a large number of inspections, it is necessary to significantly increase the sampling area. However, in the case of an XRF analyzer, there are limitations in the set resolution and scan speed. Therefore, it took a long time to scan a large-area sample film at the set resolution and scan speed. Therefore, such a detection method can only be applied to the extent of experiments at the laboratory level, and it has been difficult to quickly inspect a large number of samples to meet the mass production environment of the factory.

Prior Art Documents

Patent Documents

[0010] Patent Document 1 Korean Patent Publication No. 10-2014-0048370 Summary of the Invention Problems to be Solved by the Invention

[0011] The present invention has been devised to solve the above problems, and provides a foreign matter detection device and a foreign matter detection method capable of detecting foreign matters contained in an electrode active material with a high detection rate.

[0012] Further, the present invention provides a foreign matter detection device and a foreign matter detection method capable of quickly inspecting a large-capacity electrode active material. Means for Solving the Problems

[0013] A foreign matter detection device for an electrode active material according to an embodiment of the present invention includes a suspension tank containing a suspension in which the electrode active material is uniformly dispersed, a filter having a predetermined pore size for filtering the suspension transferred from the suspension tank to collect foreign matters in the electrode active material, and an analyzer for analyzing the filter on which the foreign matters are collected to detect at least one of the type, number, shape, and size of the foreign matters.

[0014] According to an embodiment, the suspension tank may include a stirring member for stirring and dispersing the electrode active material and foreign matters.

[0015] As an embodiment, the suspension may be transferred to the filter at a constant flow rate.

[0016] As an example, the suspension may be transferred and filtered to the filter in a sealed state from the outside.

[0017] As an example, it includes a foreign matter collection kit having a liquid inlet, a liquid outlet, and a flow channel connecting the liquid inlet and the liquid outlet, and being sealed except for the liquid inlet and the liquid outlet, and the filter can be installed in the liquid flow channel between the liquid inlet and the liquid outlet.

[0018] The liquid inlet of the foreign matter collection kit and the suspension tank can be connected by a sealed conduit.

[0019] As an embodiment, it may further include a peristaltic pump installed in the sealed conduit between the suspension tank and the foreign matter collection kit for transferring the suspension at a constant flow rate.

[0020] The filter can be a polymer filter.

[0021] As an example, the analyzer can be an XRF analyzer that irradiates an X-ray on the filter on which foreign matters are collected and qualitatively and quantitatively analyzes the foreign matters from the secondary X-rays generated for each type of foreign matter.

[0022] The foreign matter collection area of the filter can be set as the area within which the X-ray scan of the XRF analyzer can be completed within a predetermined time under the set resolution and set scan speed conditions of the XRF analyzer.

[0023] As another aspect of the present invention, a method for detecting foreign matters in an electrode active material includes steps of suspending the electrode active material in a liquid and stirring to produce a suspension in which the electrode active material is uniformly dispersed, passing the suspension through a filter having a predetermined pore size to collect the foreign matters in the electrode active material on the filter, and analyzing the filter on which the foreign matters are collected to detect at least one of the type, number, shape, and size of the foreign matters.

[0024] The suspension can be transferred to the filter at a constant flow rate.

[0025] As an example, the suspension can be transferred to and filtered by the filter in a state sealed from the outside.

[0026] In the foreign matter detection method, at least one of the type and the number of foreign matters can be detected by an XRF analyzer that irradiates an X-ray on the filter on which foreign matters are collected and performs qualitative and quantitative analysis of the foreign matters from the secondary X-rays generated for each type of foreign matter.

[0027] In this detection method, the foreign matter collection area of the filter can be set as the area where the X-ray scan of the XRF analyzer can be completed within a predetermined time under the set resolution and set scan speed conditions of the XRF analyzer.

Effect of the Invention

[0028] According to the present invention, foreign matters contained in the electrode active material can be detected with a high probability. That is, foreign matters contained in the electrode active material can be detected with a high detection rate (recovery rate).

[0029] Further, according to the present invention, a large amount of electrode active material can be analyzed to detect foreign matters.

[0030] Further, according to the present invention, in consideration of the resolution and scan speed of the analyzer, the electrode active material can be analyzed in a short time, and foreign matters can be detected quickly.

Brief Description of the Drawings

[0031]

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Embodiments for Carrying Out the Invention

[0032] Hereinafter, the present invention will be described in detail. Before that, the terms and words used in this specification and the claims should not be construed as being limited to their ordinary or dictionary meanings, and based on the principle that the inventor can appropriately define the concept of the terms in order to explain his invention in the best way, they can be construed as meanings and concepts consistent with the technical idea of the present invention.

[0033] In the present invention, terms such as "including" and "having" are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the presence or addition possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof. Also, when a certain part is said to be "connected" to another part, this includes being physically directly or indirectly connected.

[0034] Terms such as "upper" or "lower", "front" or "rear", or "arrangement" or "array" in the present invention are not meant to have a restrictive meaning and can be interpreted as illustrative words indicating position and orientation.

[0035] Hereinafter, the present invention will be described in detail.

[0036] <Foreign matter detection device>

[0037] (First Embodiment) FIG. 1 is a schematic diagram showing a foreign matter detection device for an electrode active material according to a first embodiment of the present invention, and FIGS. 2 and 3 are a schematic diagram and a cross-sectional view of a foreign matter collection kit included in the foreign matter detection device.

[0038] A foreign matter detection device 10 for an electrode active material according to a first embodiment of the present invention includes a suspension tank 100 containing a suspension L in which the electrode active material is uniformly dispersed, a filter 350 having a predetermined pore size and filtering the suspension L transferred from the suspension tank 100 to collect foreign matters in the electrode active material, and an analyzer 400 that analyzes the filter 350 on which foreign matters are collected to detect at least one of the type of foreign matter, the number of foreign matters, the shape of foreign matters, and the size of foreign matters.

[0039] The electrode active material may include a predetermined positive electrode active material and a negative electrode active material. The positive electrode active material may be a lithium-containing oxide, and as the lithium-containing oxide, a lithium-containing transition metal oxide may be used.

[0040] For example, the lithium-containing transition metal oxide is Li x CoO2 (0.5 < x < 1.3), Li x NiO2 (0.5 < x < 1.3), Li x MnO2 (0.5 < x < 1.3), Li x Mn2O4 (0.5 < x < 1.3), Li x (Ni a Co b Mn c )O2 (0.5 < x < 1.3, 0 < a < 1, 0 < b < 1, 0 < c < 1, a + b + c = 1), Lix Ni 1-y Co y O2 (0.5 < x < 1.3, 0 < y < 1), Li x Co 1-y Mn y O2 (0.5 < x < 1.3, 0 ≤ y < 1), Li x Ni 1-y Mn y O2 (0.5 < x < 1.3, 0 ≤ y < 1), Li x (Ni a Co b Mn c )O4 (0.5 < x < 1.3, 0 < a < 2, 0 < b < 2, 0 < c < 2, a + b + c = 2), Li x Mn 2-z Ni z O4 (0.5 < x < 1.3, 0 < z < 2), Li x Mn 2-z Co z O4 (0.5 < x < 1.3, 0 < z < 2), Li x CoPO4 (0.5 < x < 1.3) and Li x It can be any one selected from the group consisting of FePO4 (0.5 < x < 1.3) or a mixture of two or more of these. Further, the lithium-containing transition metal oxide can also be coated with a metal such as aluminum (Al) or a metal oxide. In addition to the lithium-containing transition metal oxide, one or more of sulfide, selenide, and halide can be used.

[0041] The negative electrode active material may include a carbon material, lithium metal, silicon, tin, or the like. When a carbon material is used as the negative electrode active material, both low-crystalline carbon and high-crystalline carbon can be used. Representative examples of low-crystalline carbon include soft carbon and hard carbon, and representative examples of high-crystalline carbon include natural graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, meso-carbon microbeads, mesophase pitches, and high-temperature calcined carbon such as petroleum or coal tar pitch-derived cokes.

[0042] Foreign substances are inevitably mixed into the electrode active material during the manufacturing process of the active material. Typical foreign substances include various types of metal foreign substances. For example, there are metal foreign substances such as Fe, Cu, Cr, Zn, Mn, Co, Ni, and Ti. Mn, Co, Ni, etc. can form the active material in the form of compounds. The free metal elements that are not combined can become foreign substances that cannot participate in the electrical reaction. In particular, there are many such metal foreign substances in the positive electrode active material. When manufacturing a secondary battery with an electrode containing such foreign substances, unexpected defects such as low voltage defects may occur. The size of the foreign substances is smaller than the size of the electrode active material. Therefore, the foreign substances in the active material can be collected by a filter 350 with a predetermined pore size having a pore size smaller than that of the foreign substances. The electrode active material smaller than the foreign substances can pass through the filter 350 and be separated from the foreign substances. Also, the metal foreign substances can be adsorbed and collected by a magnetic member.

[0043] As described above, conventionally, the electrode active material was in the form of powder, and a dry method was used to detect foreign substances by filtering the powder to detect metallic foreign substance powder. However, in the conventional method, the loss rate of foreign substances was high, and the foreign substance detection rate was extremely low. Alternatively, it was difficult to rapidly inspect a large volume of electrode active material to detect foreign substances in accordance with the mass production rate of secondary batteries.

[0044] The present invention detects foreign substances by a so-called wet detection method in which an electrode active material is suspended in a predetermined liquid to form a suspension L, and the suspension L is continuously passed through a filter 350 to collect foreign substances.

[0045] For this purpose, the foreign substance detection device 10 of the present invention includes a suspension tank 100, a foreign substance collection filter 350, and a foreign substance analyzer 400.

[0046] The suspension tank 100 contains a suspension L in which the electrode active material is uniformly dispersed. The suspension L means a mixture on a suspension in which small particles are spread in a liquid without being dissolved, like muddy water. That is, the active material and foreign substances contained therein in the suspension L of the electrode active material are spread in the liquid without being dissolved in the liquid. Therefore, when the suspension L is passed through a predetermined foreign substance collection filter 350, foreign substances can be collected on the filter 350.

[0047] Referring to FIG. 1, a suspension tank 100 provided with a stirring member 110 for uniformly dispersing the electrode active material and foreign substances by stirring is shown.

[0048] The suspension tank 100 is a kind of container that can uniformly disperse the electrode active material by suspending and stirring the electrode active material in a predetermined liquid. In FIG. 1, the stirring member 110 includes a rotating shaft that rotates by a predetermined drive source (not shown) such as a motor, and a stirring blade 111 coupled to the rotating shaft. However, the configuration and form of the stirring member are not limited to this, and it goes without saying that other forms of stirring members that can preferably stir the liquid can also be adopted.

[0049] The liquid in which the electrode active material is suspended may be any liquid as long as it does not dissolve the active material and foreign substances and has the property that the active material and foreign substances can float in the liquid on the suspension. For example, RO water (Reverse Osmosis water) or DI water (Deionized water) can be used as the suspension liquid. RO water is pure water produced by applying pressure with a reverse osmosis treatment device to remove salts and filtering. DI water is water from which ions have been removed by ion exchange resin. That is, purified water from which impurities such as ions, solid particles, microorganisms, and organic substances contained in water have been removed can be used as the suspension liquid.

[0050] A suspension L in which the active material and foreign substances are uniformly dispersed can be obtained by stirring. Therefore, when the suspension L in which the sample is uniformly dispersed is passed through the filter 350, a large amount of the sample can be filtered without clogging the filter 350. In particular, by continuously transferring the suspension to the filter 350 at a constant flow rate, a large amount of foreign substances can be accumulated and collected on the filter 350 with a limited area. According to an exemplary embodiment, according to the present invention, it is possible to analyze a large volume of 50 to 100 g of the electrode active material. However, the amount of the active material is not limited thereto. Compared with the conventional method that was only capable of sampling at the 10 mg level, according to the present invention, a large volume of the active material hundreds to thousands of times or more can be analyzed quickly.

[0051] The filter 350 filters the suspension transferred from the suspension tank 100, allows the active material particles with a small size to pass through, and collects only the foreign substances with a large size. For this purpose, the filter 350 may have a pore size corresponding to the size of the foreign substances to be collected. For example, in order to collect metal foreign substances having a length or diameter of 45 μm or more, a filter 350 with a pore size of 45 μm can be used. Or, in order to collect metal foreign substances having a length or diameter of 65 μm or more, a filter 350 with a pore size of 65 μm can be used.

[0052] The filter 350 can adopt materials suitable for filtering such as non-woven fabric, polymer, and stainless steel. However, since a metal filter can provide a magnetic repulsive force against metal foreign objects having weak magnetism or paramagnetism, it can be said that it is preferable to use a filter other than metal. For example, as a polymer filter, a filter made of polyethylene (PE) can be used.

[0053] To prevent contamination of the suspension, the suspension in the suspension tank 100 can be transferred to the filter 350 in a sealed state from the outside. Also, in order to prevent contamination from the outside during the filtering process, the filter 350 needs to be installed in an environment sealed from the outside.

[0054] For this purpose, the foreign object detection device 10 of the present invention can include a sealed conduit 200 and a foreign object collection kit 300.

[0055] Referring to FIG. 1, the sealed conduit 200 is connected between the suspension tank 100 and the foreign object collection kit 300. At the connection part of the sealed conduit 200 and the suspension tank 100, and at the connection part of the sealed conduit 200 and the foreign object collection kit 300, a predetermined sealing member (for example, an O-ring) can be installed for airtightness. The sealed conduit 200 can prevent leakage of the suspension and transfer a fixed amount of the suspension to the foreign object collection kit 300. Also, the sealed conduit 200 can prevent the inflow of external air and prevent the mixing of unnecessary bubbles that interfere with foreign object collection. A predetermined pump can be adopted to transfer a fixed flow rate of the suspension from the suspension tank 100 to the filter 350.

[0056] The above-mentioned sealed conduit 200 can be manufactured from a flexible material. For example, a tube or hose made of a flexible plastic resin (for example, urethane resin) or silicone resin can be used as the sealed conduit 200. By bending the flexible hose, the transfer path of the suspension can be freely set between the suspension tank 100 and the filter 350.

[0057] The foreign matter collection kit 300 is a type of filter fixture that protects the filter 350 from external influences, fixes the filter 350 in a certain position, and collects foreign matter on a specific filter area.

[0058] Referring to FIGS. 2 and 3, the foreign matter collection kit 300 includes a liquid inlet I1, a liquid outlet O2, and flow channels 313 and 323 that connect the liquid inlet I1 and the liquid outlet O2. The foreign matter collection kit 300 is configured to be sealed from the outside except for the liquid inlet I1 and the liquid outlet O2. Therefore, the filter 350 can be protected from the external environment within the foreign matter collection kit 300 and stably collect foreign matter. The filter 350 is installed in the flow channels 313 and 323.

[0059] In addition, the liquid inlet I1 of the foreign matter collection kit 300 and the suspension tank 100 are connected by a sealed conduit 200. A sealing member such as an O-ring can be installed at the connection part of the liquid inlet I1 and the sealed conduit 200 as described above.

[0060] Referring to FIGS. 2 and 3, the foreign matter collection kit 300 has a hollow main body part provided with a first hollow channel 313. Both ends of the first hollow channel 313 are opened to the upper surface 311 and the lower surface 312 of the hollow main body part respectively, forming an upper kit part 310 with a first inlet I1 and a first outlet O1, and a hollow main body part provided with a second hollow channel 323. Both ends of the second hollow channel 323 are opened to the upper surface 321 and the lower surface 322 of the hollow main body part respectively, including a lower kit part 320 with a second inlet I2 and a second outlet O2. The first inlet I1 serves as the liquid inlet I1 of the foreign matter collection kit 300, and the second outlet O2 serves as the liquid outlet. Also, the first hollow channel 313 and the second hollow channel 323 serve as the flow channels of the foreign matter collection kit 300.

[0061] The upper kit part 310 and the lower kit part 320 are joined so that the first hollow channel 313 and the second hollow channel 323 are concentrically arranged, whereby the foreign matter collection filter 350 can be fixed between the upper kit part 310 and the lower kit part 320.

[0062] The first inlet I1, the first hollow channel 313 and the first outlet O1, and the second inlet I2, the second hollow channel 323 and the second outlet O2 are concentrically arranged. The sealed conduit 200 is connected to the first inlet I1 which is a liquid injection port. Accordingly, the suspension introduced into the sealed conduit 200 is transferred to the filter 350 through the first inlet I1 - the first hollow channel 313 - the first outlet O1. The liquid (mainly containing the electrode active material) filtered by the filter 350 is discharged downward through the second inlet I2 - the second hollow channel 323 - the second outlet O2. Thus, since the foreign matter collection kit 300 allows the suspension to pass from the upper part to the lower part, it has a structure capable of smoothly filtering the suspension by gravity. The diameters and lengths of the first hollow channel 313 and the second hollow channel 323 can be suitably determined in consideration of the flow rate and flow velocity of the suspension. For example, the total length of the overall flow channel combining the first hollow channel 313 and the second hollow channel 323 can be determined in the range of 45 to 70 mm, but is not limited thereto. Accordingly, the height of the entire foreign matter collection kit 300 combining the upper kit part 310 and the lower kit part 320 can also be determined in the range of 45 to 70 mm, but is not limited thereto.

[0063] The diameters of the first inlet I1, the first hollow channel 313 and the first outlet O1, and the second inlet I2, the second hollow channel 323 and the second outlet O2 can be the same. However, as will be described later, the diameters of the first hollow channel 313 and the second hollow channel 323 can also vary along the height direction.

[0064] In FIG. 2, the diameter φ1 of the foreign matter collection kit, the diameter φ2 of the filter and the filter mounting groove provided in the foreign matter collection kit, the first hollow channel, the second hollow channel, and the diameter φ3 of the foreign matter collection region are shown respectively.

[0065] As an exemplary embodiment, the upper kit part 310 and the lower kit part 320 can be joined by a fitting connection or a screw connection. For example, among the surfaces of the upper kit part 310 and the lower kit part 320 facing each other, one surface is provided with a fitting protrusion 312a, and one of the other surfaces is provided with an insertion groove 321a. By connecting the fitting protrusion 312a to the insertion groove 321a, the upper kit part 310 and the lower kit part 320 can be joined (see FIGS. 2 and 3). Alternatively, screw threads A1 and A2 having a meshing shape with each other are provided on the opposing surfaces of the upper kit part 310 and the lower kit part 320, and the upper kit part 310 and the lower kit part 320 can be screw-connected (see FIGS. 4 and 5). Here, the opposing surfaces of the upper kit part 310 and the lower kit part 320 can be horizontal surfaces. Alternatively, as shown in FIGS. 4 and 5, when a step is formed on the opposing surfaces of the upper kit part 310 and the lower kit part 320, the opposing surfaces can be vertical surfaces that form a part of the stepped surface. Therefore, as shown in FIGS. 4 and 5, by arranging screw threads A1 and A2 having a meshing shape with each other on the opposing vertical surfaces of the upper kit part 310 and the lower kit part 320, the upper kit part 310 and the lower kit part 320 can be screw-connected. Since the upper kit part 310 and the lower kit part 320 are joined and the filter 350 is exposed only within the suspension permeation region (the first hollow channel 313, the second hollow channel 323), foreign substances are collected only in such a permeation region. Also, since the upper kit part 310 and the lower kit part 320 are firmly joined by screws or the like, foreign substances do not diffuse outside the permeation region of the filter 350.

[0066] The filter 350 can be concentrically installed between the first outlet O1 and the second inlet I2 so as to cover the entire first outlet O1 and the second inlet I2. In this case, the area of the foreign substance collection region 351 of the filter 350 is the same as the areas of the first outlet O1 and the second inlet I2.

[0067] A receiving groove for receiving the filter 350 may be provided on at least one of the upper surface 321 of the lower kit part 320 and the lower surface 312 of the upper kit part 310. For example, only a filter receiving groove 321b may be arranged on the upper surface 321 of the lower kit part 320, and the lower surface 312 of the upper kit part 310 facing it may be a flat surface simply covering the filter 350. Conversely, only a filter receiving groove 312b may be arranged on the lower surface 312 of the upper kit part 310, and the upper surface 321 of the lower kit part 320 facing it may be a flat surface simply covering the filter 350. Alternatively, as shown in FIG. 3, grooves 312b and 321b for receiving the filter 350 may be provided on both the lower surface 312 of the upper kit part 310 and the upper surface 321 of the lower kit part 320. Due to such receiving grooves, the filter 350 can be stably seated between the upper kit part 310 and the lower kit part 320, and the filter 350 can be fixed without flowing in the receiving groove when the upper kit part 310 and the lower kit part 320 are joined.

[0068] As another example, as shown in FIG. 5, a receiving groove 321b for receiving the filter 350 is provided on one of the upper surface 321 of the lower kit part 320 and the lower surface 312 of the upper kit part 310, and a protruding cover part 312P that is inserted into the receiving groove and covers the filter 350 is provided on the other of the upper surface 321 of the lower kit part 320 and the lower surface 312 of the upper kit part 310. In this case, when the upper kit part 310 and the lower kit part 320 are joined, the filter 350 can be stably fixed and maintained by the distance between the receiving groove 321b and the protruding cover part 312P.

[0069] The foreign matter collection kit 300 may be made of a material excellent in chemical resistance, abrasion resistance, and strength. For example, the foreign matter collection kit 300 may be manufactured using PEEK (Poly Ether Ether Keton) that is excellent in chemical resistance and strength.

[0070] FIGS. 4 and 5 are schematic diagrams and cross-sectional views of another example of the foreign matter collection kit 300' included in the foreign matter detection device 10.

[0071] On the upper surface 311 of the upper kit portion 310 of the foreign matter collection kit 300', an injection pipe 314 that communicates with the first hollow channel 313 and extends upward is provided. Since the injection pipe 314 protrudes upward, it is easy to couple with the above-mentioned sealed conduit 200. For example, the injection pipe 314 can be firmly fitted into a urethane hose, and the sealed conduit 200 can be connected to the foreign matter collection kit 300 while maintaining airtightness. Also, since the injection pipe 314 of a predetermined length protrudes and is inserted into the sealed conduit 200 by a certain length, the risk of leakage of the suspension can be prevented. Further, since the injection pipe 314 extended upward serves as a funnel, the operation of injecting the suspension into the foreign matter collection kit 300 at the inlet I1' of the injection pipe 314 also becomes very simple.

[0072] In the example of FIG. 3, the diameters φ3 of the first hollow channel 313 and the second hollow channel 323 were the same. However, in order to make the flow of the suspension smooth and the discharge of the liquid passing through the filter 350 smooth, the diameter of the hollow channel can be changed along the height. For example, a tapered channel portion 313b, 323b in which the channel cross-sectional area increases toward the outlet of each hollow channel can be provided at the lower part of at least one of the first hollow channel 313 and the second hollow channel 323.

[0073] As shown in FIG. 5, the first hollow channel 313 can be composed of an upper channel 313a with a constant diameter and a lower channel 313b with a variable diameter. The upper channel 313a is connected to the injection tube 314 described above. The diameter of the upper channel 313a is set to be the same as the inner diameter of the injection tube 314 for a stable downward flow of the suspension. On the other hand, the lower channel 313b following the upper channel 313a has a tapered shape in which the cross-sectional area gradually increases toward the first outlet O1. That is, the lower channel 313b becomes a tapered channel portion 313b. Thereby, the suspension flowing downward can be introduced onto the filter 350 more smoothly and with a larger flow rate. In this case, the second inlet I2, the second hollow channel 323, and the second outlet O2 of the lower kit portion 320 can have the same diameter as shown in FIG. 3. However, in this case, the diameters of the second inlet I2, etc. can be set to be the same as the diameter of the first outlet O1 of the expanded tapered channel portion 313b.

[0074] Alternatively, as shown in FIG. 5, the second hollow channel 323 can be composed of an upper channel 323a with a constant diameter and a lower channel 323b with a variable diameter. The upper channel 323a is connected to the first outlet O1 of the first hollow channel 313. The diameter of the upper channel 323a is set to a constant diameter for a stable downward flow of the suspension. On the other hand, the lower channel 323b following the upper channel 323a has a tapered shape in which the cross-sectional area gradually increases toward the second outlet O2. That is, the lower channel 323b becomes a tapered channel portion 323b. Thereby, the suspension containing the filtered active material can be discharged more smoothly and with a larger flow rate.

[0075] FIG. 5 illustrates the case where both the first hollow channel 313 and the second hollow channel 323 have tapered channel portions, but it is also possible to provide a tapered channel portion only in either the first hollow channel 313 or the second hollow channel 323.

[0076] The foreign object collection kit 300' in FIGS. 4 and 5 is provided with a plurality of stepped portions S11, S12, S21, and S22 on the opposing surfaces of the upper kit portion 310 and the lower kit portion 320. By connecting the stepped portions S11, S12, S21, and S22, the upper kit portion 310 and the lower kit portion 320 are more firmly connected, and a filter can be more firmly fixed between the upper kit portion 310 and the lower kit portion 320. The upper kit portion 310 is provided with two stepped portions on the lower surface 312, and the horizontal plane facing the lower kit portion 320 is divided into three (312-1, 312-2, 312-3). Also, the lower kit portion 320 is provided with two stepped portions on the upper surface 321, and the horizontal plane facing the upper kit portion 310 is divided into three (321-1, 321-2, 321-3). A vertical surface is arranged between adjacent horizontal planes among the three horizontal planes.

[0077] Referring to the drawings, a first lower surface stepped portion S11 is provided outside the lower surface 312 of the upper kit portion. Also, outside the upper surface 321 of the lower kit portion, a first upper surface stepped portion S21 having a shape that meshes with the first lower surface stepped portion S11 is provided. The first lower surface stepped portion S11 and the first upper surface stepped portion S21 each include two horizontal planes 312-1, 312-2, 321-1, 321-2 and one vertical surface interposed therebetween. At this time, the opposing vertical surfaces of the first lower surface stepped portion S11 and the first upper surface stepped portion S21 can be screwed together with screw threads A1, A2 that mesh with each other. The vertical length of the screw portion arranged on the vertical surface is determined by the descending distance of the upper kit portion 310 due to screw connection. As will be described later, the upper kit portion 310 and the lower kit portion 320 are connected so that the second lower surface stepped portion S12 and the second upper surface stepped portion S22 also mesh. In this case, if the second lower surface stepped portion S12 approaches the second upper surface stepped portion S22 excessively and presses, the filter 350 located therebetween may be damaged. Therefore, it is preferable that the vertical length of the screw portion is set to be the same as the descending distance of the upper kit portion 310 during screw connection and the descending distance of the second lower surface stepped portion S12, so as to avoid excessive pressing of the filter 350.

[0078] Inside the lower surface 312 of the upper kit part, a second lower surface step part S12 following the first lower surface step part S11 is provided. Also, inside the upper surface 321 of the lower kit part, a second upper surface step part S22 is provided following the first upper surface step part S21 and having a shape that meshes with the second lower surface step part S12. The filter 350 is installed between the opposing horizontal planes 312-3 and 321-3 of the second upper surface step part S22 and the second lower surface step part S12. The side surface of the filter 350 is restricted by the vertical surface of the second upper surface step part S22, preventing the movement of the filter. When the upper kit part 310 and the lower kit part 320 are screwed together, the filter is supported and fixed between the horizontal planes of the second lower surface step part S12 and the second upper surface step part S22 and by the vertical surface of the second upper surface step part S22. Thereby, even when pressure is applied by the downward flow of the suspension, the filter 350 is stably maintained, enabling continuous filtering of foreign matter.

[0079] As an example, it further includes a filter mounting sheet 360 that surrounds the foreign matter collection filter 350 and is coupled to the foreign matter collection filter 350, and the filter mounting sheet 360 can be fixedly installed between the upper kit part 310 and the lower kit part 320.

[0080] The area of the foreign matter collection region 351 of the foreign matter collection filter 350 can be set to an area where X-ray scanning can be completed within a predetermined time under the set resolution and set scan speed conditions of a foreign matter analyzer 400 that scans X-rays to analyze foreign matter.

[0081] FIG. 6 is a schematic diagram showing the area of the foreign matter collection region 351 of the filter 350 applied to the present invention, and FIG. 7 is a schematic diagram showing the state where the filter 350 is attached to an inspection film.

[0082] Conventionally, since a dry method of filtering active material powder containing foreign matter by air pressure was selected, the foreign matter could not be spread over a wide area by air pressure to increase the collection density of the foreign matter. Therefore, a complicated operation of attaching the tape several times to collect the foreign matter was required. In this process, the loss rate of the foreign matter was very high, and the collection and detection efficiency of the foreign matter was very low. Or, since the foreign matter was detected together with the active material, it was difficult to detect the foreign matter in a narrow X-ray scan area.

[0083] On the other hand, in the present invention, the foreign matter is uniformly dispersed in the suspension tank 100 to form a suspension, and by continuously introducing the suspension into the filter 350, the area of the foreign matter collection region 351 of the filter 350 can be minimized. That is, by uniformly dispersing the foreign matter, the foreign matter is prevented from being unevenly distributed in the suspension, and the filter 350 is prevented from being clogged during filtering. Further, the suspension in which the foreign matter is uniformly dispersed is continuously introduced into the filter 350 having a pore size capable of filtering the foreign matter, and only the foreign matter can be intensively collected on the filter 350. By collecting the foreign matter by such a wet method or a wet pretreatment method, the foreign matter can be intensively collected in a small area.

[0084] Referring to Fig. 6(a), the small central circle is the boundary line of the area collected by the filter 350 with respect to the large outer circle. It can be seen that the diameter φ3 of the small central circle is much smaller than the diameter φ2 of the large outer circle. The diameter φ3 of the central circle is the same as the diameter φ3 of the first outlet O1 of the upper kit part 310 and the second inlet I2 of the lower kit part 320. As an exemplary embodiment, the diameter φ3 of the central circle can be about 1 to 2 cm. However, the diameter φ3 and area of the foreign matter collection area 351 are not limited to this, and can be made larger or smaller according to the resolution and scan speed of the analyzer 400. By performing an X-ray scan on a circle with such a small area, foreign matter can be inspected quickly despite the limited scan speed. Also, a large amount of active material can be inspected quickly while satisfying the set resolution. Thus, according to the present invention, filtering can be performed only on a part of the filter 350 instead of the whole filter 350. The area of the filter 350 that is not filtered becomes the part fixed between the upper kit part 310 and the lower kit part 320.

[0085] According to the present invention, since the area of the foreign matter collection area 351 can be minimized, the filter 350 can also be made small to match its area. For example, as shown in Fig. 6(b), an exemplary embodiment may include a filter mounting sheet 360 that is joined to surround the filter 350 with a small area. The filter mounting sheet 360 is a support sheet to which the filter 350 is joined and mounted. Also, when the filter mounting sheet 360 is fixedly installed between the upper kit part 310 and the lower kit part 320, the filter can be accurately positioned at the filtering position where the suspension passes through. In this case, the diameter of the filter 350 is the same as the diameter φ3 of the first outlet O1 of the upper kit part 310 and the second inlet I2 of the lower kit part 320, or it is sufficient if it is slightly larger than that.

[0086] FIG. 7 is a schematic view showing a state in which the filter 350 is attached to the inspection film F. In order to inspect with the foreign matter analyzer 400, the filter 350 can be attached to the inspection film F, and the inspection film can be put into the analyzer 400 for analysis. As shown in the figure, instead of scanning the entire area of the filter, only a small circular portion in the center of the filter needs to be scanned, so the inspection speed and efficiency are greatly improved.

[0087] The present invention includes an analyzer 400 that analyzes the filter 350 on which foreign matters are collected to detect at least one of the type, number, shape, and size of the foreign matters. As described above, according to the present invention, target foreign matters can be accumulated and collected in a small area. Therefore, it can be expected that the foreign matter detection efficiency will be greatly improved regardless of the analyzer 400 used.

[0088] As one of the above analyzers 400, an XRF analyzer can be used. XRF (X-Ray Fluorescence) analysis is a method of analyzing a sample by analyzing secondary fluorescent X-rays generated inside the sample when irradiating (scanning) the sample to be inspected with X-rays. By using the XRF analyzer 400, the filter 350 on which foreign matters are collected is irradiated with X-rays, and the foreign matters can be qualitatively and quantitatively analyzed from the secondary fluorescent X-rays generated for each type of foreign matter. Fluorescent X-rays have different wavelengths and energies for each element. Therefore, qualitative analysis of grasping the type of foreign matter by the wavelength or energy of the secondary fluorescent X-rays is possible.

[0089] Also, the elements of the foreign matter can be identified or the number of foreign matters can be grasped by mapping analysis obtained from a two-dimensional image acquired by X-ray scanning. For example, if the foreign matter collection region 351 is irradiated with X-rays and scanned, a mapping map having shadows in pixel units can be obtained. The number of foreign matters can also be grasped by predetermined software having an algorithm for converting the shadows of the mapping map into numbers. Therefore, quantitative analysis of foreign matters in the electrode active material is also possible.

[0090] On the one hand, the shape and size of foreign objects can be grasped by, for example, optical microscopes such as SEM and TEM, or electron microscopes. In recent years, an analyzer 400 in which a microscope device such as SEM is integrated with the XRF analyzer 400 has also been put on the market. Therefore, all of the type, number, shape, and size of foreign objects can be grasped with such a single analyzer. What is important is not which analyzer to use, but rather whether the degree of accumulation of foreign object collection can be increased and the area of the foreign object collection region 351 can be minimized to improve the foreign object detection efficiency regardless of which analyzer is used. The present invention is for achieving such a problem.

[0091] The foreign object detection device 10 of the present invention can set the area of the foreign object collection region 351 of the filter 350 as the area within which the X-ray scan of the XRF analyzer 400 can be completed within a predetermined time under the set resolution and set scan speed conditions of the XRF analyzer 400. That is, as shown in FIG. 6, the area of the foreign object collection region 351 can be made small, and when scanning such a small area with an XRF analyzer 400 having a certain resolution and scan speed, the analysis can be completed within several minutes to several tens of minutes (for example, several minutes to 30 minutes). Therefore, even including the above-described suspension and filtering times, one analysis does not take one hour, so the electrode active material of a specific lot can be quickly inspected in the mass production process and can be adapted to mass production.

[0092] On the other hand, the shape of the foreign object collection region 351 is not limited to a circular shape as shown in FIG. 6.

[0093] That is, by changing the shapes of the first inlet I1, the first hollow channel 313, and the first outlet O1 to rectangular, elliptical, or other shapes, the shape of the foreign object collection region 351 can be changed to rectangular, elliptical, or any other shape as much as possible.

[0094] The shapes of the second inlet I2, the second hollow channel 323, and the second outlet O2 can also be changed to rectangular, elliptical, or other shapes.

[0095] (Second Embodiment) FIG. 8 is a schematic diagram showing a foreign matter detection device 20 for an electrode active material according to the second embodiment of the present invention, and FIG. 9 is a schematic diagram showing the operation of a peristaltic pump. In the second embodiment, the same points as those in the first embodiment are omitted from the description, and only the different points will be described.

[0096] Similar to the first embodiment, the foreign matter detection device 20 of the second embodiment also includes a suspension tank 100, a foreign matter collection kit 300, and an analyzer 400. The difference is that it is provided with a peristaltic pump 500 capable of transferring the suspension to the foreign matter collection kit 300 at a constant flow rate. Referring to FIG. 8, a peristaltic pump 500 for transferring the suspension at a constant flow rate is installed in a sealed conduit 200 between the suspension tank 100 and the foreign matter collection kit 300.

[0097] If the flow rate of the suspension transferred from the suspension tank 100 to the filter 350 fluctuates greatly, foreign matters may locally accumulate and clog the pores when filtered by the filter 350. Therefore, it is necessary to transfer the suspension to the filter 350 at a constant flow rate as much as possible.

[0098] The peristaltic pump 500 is a positive displacement pump and is designed based on the peristaltic principle. "Peristalsis" is a series of muscle contraction actions that move food along the digestive organs to other parts. The peristaltic pump 500 moves the fluid in the same way as the action of such digestive organs.

[0099] Referring to FIG. 9, the peristaltic pump 500 includes a pump body 510 having a space 511 inside for accommodating a fluid (suspension) conduit 200, and a rotating member 520 accommodated in the space. The rotating member 520 is rotated by a driving source such as a motor and includes rollers or shoes 521. A part 210 of the sealed conduit 200 is arranged along the inner surface of the pump body 510 of the space. As shown in FIG. 9, shoes 521 are installed at both ends of the rotating member, and the suspension can be transferred to the foreign matter collection kit 300 at a constant flow rate according to the rotation direction of the shoes 521.

[0100] When using the peristaltic pump 500, since only the tube (hose) comes into contact with the fluid, it is possible to prevent the suspension from contaminating the pump or being contaminated by the pump. Also, when the pump is not operating, backflow is prevented and the need for a check valve is eliminated.

[0101] <Foreign matter detection method>

[0102] FIG. 10 is a flowchart showing a method for detecting foreign matter in an electrode active material of the present invention.

[0103] The foreign matter detection method of the present invention includes a step (S1) of suspending an electrode active material in a liquid and stirring to produce a suspension in which the electrode active material is uniformly dispersed, a step (S3) of passing the suspension through a filter having a predetermined pore size and collecting foreign matter in the electrode active material on the filter, and a step (S4) of analyzing the filter on which the foreign matter is collected to detect at least one of the type, number, shape, and size of the foreign matter.

[0104] For example, foreign matter detection can be performed with a foreign matter detection device 10, 20 as shown in FIG. 1 or FIG. 8.

[0105] First, the electrode active material is suspended in a liquid such as DI water or RO water and stirred. As the electrode active material, a positive electrode active material or a negative electrode active material can be used. In the method of this embodiment, the case of filtering metal foreign matter having a specific size or more in the positive electrode active material will be described by way of example. For example, 50 to 100 g of a large-capacity positive electrode active material is suspended in 1 L of DI water. Stirring can be performed in a suspension tank for about 5 to 10 minutes to uniformly disperse the active material in the liquid and produce a suspension.

[0106] The foreign object detection method of the present invention may further include a step (S2) of transferring a suspension to a filter at a constant flow rate. At this time, a sealed conduit may be used to transfer the suspension in a state sealed from the outside. For example, a silicone tube (hose) or a urethane tube (hose) may be employed as the sealed conduit. In order to transfer the suspension at a constant flow rate, a peristaltic pump 500 as shown in FIG. 9 may be installed on the sealed conduit between the suspension tank and the foreign object collection kit. For example, the suspension may be transferred from the suspension tank to the foreign object collection kit 300 by the peristaltic pump at a flow rate of 500 to 1000 ml / min.

[0107] When the filter 350 is installed in the foreign object collection kit 300 as shown in FIGS. 2 and 4, filtering can be performed in an environment protected from the outside. For example, the filter 350 is positioned between the upper kit part 310 and the lower kit part 320, and the upper kit part 310 and the lower kit part 320 are joined to fix the filter 350 between the upper kit part 310 and the lower kit part 320. When the remaining portion of the filter 350 other than the foreign object collection region 351 (or the filter mounting sheet 360 in FIG. 6) is mounted in the mounting groove and the upper kit part 310 and the lower kit part 320 are joined, it is possible to prevent foreign objects from diffusing outside the foreign object collection region 351. That is, the foreign object collection region 351 can be limited only to the region through which the suspension permeates.

[0108] Also, since the areas other than the upper inlet (first inlet I1) of the upper kit part 310 and the lower outlet (second outlet O2) of the lower kit part 320 are sealed, it is possible to prevent contamination of the filter and the like.

[0109] For example, in order to collect foreign matter in the range of 40 to 65 μm, a filter 350 having a corresponding pore size can be used. For example, a filter made of a polymer material having a pore size of 40 μm can be used. Pass the suspension through such a filter 350 to collect the foreign matter in the electrode active material on the filter 350 (S3). When the suction of the suspension by the peristaltic pump is completed, discharge the sufficiently filtered liquid for a predetermined time (for example, 1 minute) through the connecting tube connected to the first outlet O1. By ensuring that the filtrate is discharged for a certain period of time, a sufficient margin time can be given for the foreign matter to be sufficiently filtered by the filter 350.

[0110] When the filtering is completed, analyze the filter 350 on which foreign matter has been collected to detect at least one of the type of foreign matter, the number of foreign matters, the shape of the foreign matter, and the size of the foreign matter (S4).

[0111] After the filtering is completed, disassemble the foreign matter collection kit 300 to recover the filter 350. For inspection, for example, as shown in FIG. 7, attach the filter 350 to the inspection film F and place the inspection film in the analyzer 400 for analysis.

[0112] An XRF analyzer 400 can be used for foreign matter analysis. The XRF analyzer can irradiate the filter 350 with X-rays to perform qualitative and quantitative analysis of foreign matter from the secondary X-rays generated for each type of foreign matter. The XRF analyzer 400 can detect at least one of the type of foreign matter and the number of foreign matters. Also, the shape and size of the foreign matter can be detected by a microscope attached to the XRF analyzer 400 or a separate analyzer 400.

[0113] As described above, according to the present invention, the area of the foreign matter collection region 351 of the filter 350 can be minimized by wet pretreatment and filtering. In order to obtain a detection target image with excellent resolution, the resolution of the XRF analyzer 400 is determined within a predetermined range. Also, the scan speed of the XRF analyzer 400 is determined. When the area of the foreign matter collection region 351 is small, the X-ray scan can be completed within a short time under such set resolution and set scan speed conditions. Therefore, according to the foreign matter detection method of the present invention, the analysis speed of the XRF analyzer 400 can be increased and the analysis time can be shortened.

[0114] As an example, it takes about 5 to 10 minutes for the production of the suspension and the pretreatment of filtering, and the XRF analysis can also be performed within 30 minutes. Further, for example, an electrode active material with a large capacity of about 100 g can be analyzed. This amount of active material corresponds to one semi-finished product (Lot). According to the present invention, since the detection time can be shortened, about 80 to 100 lots can be inspected in a day, which can meet the mass production speed of electrodes and batteries.

[0115] Also, the present invention has high collection efficiency and is very excellent in the detection rate of foreign matters. Therefore, the type, number, shape, size, etc. of foreign matters in the electrode active material can be detected with a high probability. Thereby, the quality of the electrode active material can be evaluated. For example, conformity and non-conformity judgments can be made according to the type and number of foreign matters. When manufacturing a battery with a suitable electrode active material by evaluating the quality in this way, the proportion of defective battery cells can be significantly reduced.

[0116] Therefore, another aspect of the present invention may provide a secondary battery manufacturing method including a step of evaluating the quality of the electrode active material according to the foreign matter detection result by the above foreign matter detection method, and a step of manufacturing a battery with the electrode active material selected according to the evaluation result.

[0117] FIG. 11 is a mapping map of a plurality of metal foreign matters obtained by an XRF analyzer.

[0118] The two-dimensional image obtained based on the wavelength of the secondary fluorescent X-ray was converted using predetermined software to obtain a mapping map as shown in FIG. 11. As shown in the figure, it can be seen that various types of metallic foreign substances such as Fe, Cr, Cu, Zn, Mn, Co, Ni, and Ti are present in the positive electrode active material according to the wavelength (see (a) in FIG. 11). Thus, the type of foreign substance can be grasped by the XRF analyzer 400. (b) in FIG. 11 is an enlarged view of the mapping map of Fe.

[0119] FIG. 12 shows an image of a foreign substance obtained with an electron microscope attached to the XRF analyzer 400. The shape and size of the foreign substance can be calculated from such an image of the foreign substance. The size of the foreign substance can be measured by comparing the size of the measured image with the size of the shape of the foreign substance. This can be obtained with a predetermined calculation program.

[0120] The detection process of the number of foreign substances according to the present invention will be described in the following examples.

[0121] <Example>

[0122] 100 g of NCM-based positive electrode active material powder with different amounts of foreign substance (Cu) added was suspended in 1 L of DI water, and stirred in a suspension tank 100 as shown in FIG. 1 for 8 minutes to produce a positive electrode active material suspension. Pressure was applied to the above suspension with a peristaltic pump, and it was transferred to a foreign substance collection kit made of PEEK at a flow rate of 500 ml / min. After the suction of the suspension was completed, the filtrate was drained for 60 seconds through a silicone tube connected to the lower part of the foreign substance collection kit. As the first hollow channel 313, a square tube of 15 mm × 15 mm was adopted, whereby the area of the foreign substance collection region 351 was minimized to 15 mm × 15 mm.

[0123] The foreign substance collection kit was disassembled, the filter was attached to a test film, and analyzed by an XRF analyzer (EA8000, manufactured by Hitachi, Ltd.).

[0124] An X-ray was irradiated at a scanning size of 15 mm × 15 mm by a mapping scanning method using an XRF analyzer. The resolution was 30 μm / pixel and the scanning speed was 5 ms.

[0125] Figure 13 is a graph showing the correlation between the amount of foreign matter powder and the number of foreign matters.

[0126] Figure 13 shows the correlation between the weight and the number of Cu. A correlation means that there is a certain relationship between two variables, and a correlation coefficient can be calculated to show the scale of the correlation. Since it is known as a statistical method to obtain the correlation coefficient from two variable data, a specific explanation thereof will be omitted.

[0127] Figure 13 shows the correlation coefficient between the number and the weight of foreign matters with respect to Cu contained in the same type of cathode active material as the NCM-based cathode active material used in the XRF analysis. As shown in the figure, the correlation coefficient is 0.9976, showing a correlation coefficient close to 1. Thus, it can be estimated that 2338 Cu powders are present in 0.003 g of Cu.

[0128]

Table 1

[0129] As can be seen from Table 1, the median particle size D50 of the cathode active material is 10.2 to 11.6 μm, and the maximum particle size is also 27.5 μm, so it can be seen that it passes through the above filter and is drained. The numbers of Cu in Experimental Examples 1 to 3 are 2050, 2164, and 2341, respectively. For comparison on the same basis, when converted based on a Cu weight of 0.003 g, they are 1809, 1967, and 2066, respectively.

[0130] Since 2338 powders are present in 0.003 g of Cu in Figure 13, the foreign matter detection rates in Experimental Examples 1 to 3, that is, the recovery rates of the foreign matters recovered from the introduced foreign matters, are 77%, 84%, and 88%, respectively.

[0131] Therefore, according to the foreign matter detection method of the present invention, it can be seen that foreign matter can be detected with a high probability of 83% on average.

[0132] From the above, according to the foreign matter detection device and the foreign matter detection method of the present invention, since foreign matter contained in the electrode active material can be quickly detected with a high probability, the detection reliability is greatly improved.

[0133] The above description is merely an illustrative explanation of the technical idea of the present invention. Those with ordinary knowledge in the technical field to which the present invention pertains can make various modifications and variations without departing from the essential characteristics of the present invention.

[0134] Therefore, the drawings disclosed in the present invention are for the purpose of explanation rather than for limiting the technical idea of the present invention, and the scope of the technical idea of the present invention is not limited by such drawings. The protection scope of the present invention should be interpreted according to the scope of the claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of rights of the present invention.

Explanation of Reference Numerals

[0135] (Explanation of Reference Numerals) 10, 20: Foreign matter detection device 100: Suspension tank L: Suspension 110: Stirring member 200: Sealed conduit 300, 300’: Foreign matter collection kit 310: Upper kit part 320: Lower kit part 350: Filter 351: Foreign matter collection area 360: Filter mounting sheet 400: (XRF) Analyzer F: Inspection film 500: Peristaltic pump

Claims

1. A suspension tank containing a suspension in which an electrode active material is uniformly dispersed, A filter having a predetermined pore size, for filtering the suspension transferred from the suspension tank to collect foreign matters in the electrode active material, An analyzer for analyzing the filter on which foreign matters are collected to detect at least one of the type, number, shape, and size of the foreign matters, an apparatus for detecting foreign matters in an electrode active material.

2. The suspension tank is provided with a stirring member for stirring and dispersing the electrode active material and foreign matters, the apparatus for detecting foreign matters in an electrode active material according to claim 1.

3. The suspension is transferred to the filter at a constant flow rate, the apparatus for detecting foreign matters in an electrode active material according to claim 1.

4. The suspension is transferred and filtered to the filter in a sealed state from the outside, the apparatus for detecting foreign matters in an electrode active material according to claim 1.

5. Further comprising a foreign matter collection kit having a liquid inlet, a liquid outlet, and a flow channel connecting the liquid inlet and the liquid outlet, and being sealed from the outside except for the liquid inlet and the liquid outlet, The filter is installed in the flow channel, the apparatus for detecting foreign matters in an electrode active material according to claim 1.

6. The liquid inlet of the foreign matter collection kit and the suspension tank are connected by a sealed conduit, the apparatus for detecting foreign matters in an electrode active material according to claim 5.

7. Further comprising a peristaltic pump installed in the sealed conduit between the suspension tank and the foreign matter collection kit for transferring the suspension at a constant flow rate, the apparatus for detecting foreign matters in an electrode active material according to claim 6.

8. The filter is a polymer filter, the apparatus for detecting foreign matters in an electrode active material according to claim 1.

9. The analyzer is an XRF analyzer for irradiating an X-ray to the filter on which foreign matters are collected and performing qualitative and quantitative analysis of the foreign matters from the secondary X-rays generated for each type of foreign matter, the apparatus for detecting foreign matters in an electrode active material according to any one of claims 1 to 8.

10. The foreign matter collection area of the filter is set as the area where the X-ray scan of the XRF analyzer is completed within a predetermined time under the set resolution and set scan speed conditions of the XRF analyzer, the apparatus for detecting foreign matters in an electrode active material according to claim 9.

11. Steps of suspending an electrode active material in a liquid and stirring to produce a suspension in which the electrode active material is uniformly dispersed, Passing the suspension through a filter having a predetermined pore size to collect foreign matter in the electrode active material on the filter; Analyzing the filter on which the foreign matter has been collected to detect at least one of the type of foreign matter, the number of foreign matters, the shape of foreign matters, and the size of foreign matters. A method for detecting foreign matter in an electrode active material, comprising the steps of:

12. The method for detecting foreign matter in an electrode active material according to claim 11, wherein the suspension is transferred to the filter at a constant flow rate.

13. The method for detecting foreign matter in an electrode active material according to claim 11, wherein the suspension is transferred and filtered to the filter in a sealed state from the outside.

14. Irradiating the filter on which foreign matter has been collected with X-rays, and detecting at least one of the type of foreign matter and the number of foreign matters by an XRF analyzer that qualitatively and quantitatively analyzes the foreign matter from the secondary X-rays generated for each type of foreign matter. The method for detecting foreign matter in an electrode active material according to claim 11.

15. The method for detecting foreign matter in an electrode active material according to claim 14, wherein the foreign matter collection region of the filter is set as the area where the X-ray scan of the XRF analyzer is completed within a predetermined time under the set resolution and set scan speed conditions of the XRF analyzer.

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