Apparatus and method for detecting foreign matter in electrode active material

Abstract

The disclosed invention provides a detection device for an electrode, the detection device comprising: a suspension tank in which a suspension in which an electrode active material is uniformly dispersed is held; a filter having a predetermined pore diameter and filtering the suspension transferred from the suspension tank to capture foreign matter in the electrode active material; and an analyzer that analyzes the filter in which the foreign matter is captured to detect at least one of a type, a number, a shape, and a size of the foreign matter. In addition, the disclosed invention provides a method for detecting foreign matter in an electrode active material.

Description

Technical Field

[0001] The present invention relates to a device and a method for detecting foreign matter in an electrode active material.

[0002] More particularly, the present invention relates to an apparatus and method for detecting foreign matter in an electrode active material with a high detection rate.

[0003] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0026212 filed on February 27, 2023, and the entire contents of this Korean Patent Application are incorporated herein by reference. Background Art

[0004] The secondary battery is manufactured by placing an electrode assembly in a battery case and injecting an electrolyte. The electrode assembly has a structure in which a positive electrode and a negative electrode are stacked with a separator interposed therebetween.

[0005] Electrodes such as positive or negative electrodes are manufactured by coating a current collector with an active material slurry. The electrode active material may contain a small amount of foreign matter. Foreign matter in the electrode may cause low voltage defects and deteriorate the characteristics and quality of the secondary battery cell manufactured using the electrode.

[0006] Therefore, it is important to identify foreign matter that affects the characteristics of the secondary battery by detecting the type, total number, shape, size, etc. of foreign matter in the electrode active material. To this end, foreign matter in the electrode active material should be collected and detected with a high probability. In addition, preferably, a large amount of electrode active material is checked as quickly as possible to match the production speed of mass production facilities.

[0007] One of the conventional methods for detecting foreign matter in active materials is a method of filtering electrode active material powder by applying air pressure to the upper and lower sides of a metal filter. Active material powder smaller in size than the foreign matter passes through the metal filter, and the foreign matter is collected on the surface of the metal filter. Since the air pressure causes the foreign matter to be dispersed over the entire area of ​​the filter, a large-area filter is required to collect the foreign matter. Because the foreign matter is sparsely collected in a large-area filter, the collection density is increased by repeatedly attaching or separating the tape to the filter several times. The tape with the foreign matter attached can be analyzed by, for example, an X-ray fluorescence (XRF) analyzer to identify the type of the foreign matter.

[0008] However, in this method, a large amount of foreign matter may be lost during the attachment and detachment of the tape, and thus the amount or number of foreign matter in the active material cannot be accurately identified. In addition, since a metal filter is used, the foreign matter may not be properly adsorbed on the metal filter due to the magnetic properties of the foreign matter, such as weak magnetic properties or paramagnetic properties. Therefore, the detection rate (recovery rate) of foreign matter in the electrode active material is low, and thus this method is difficult to apply to the detection of foreign matter.

[0009] In order to improve this problem, there is a method of sampling an electrode active material powder containing foreign matter onto a membrane and analyzing the sampled electrode active material powder by an analyzer. However, in this case, the foreign matter in the electrode active material is detected together with the active material, so it is difficult to check a large amount of active material. Only a small amount, such as about 10 mg of sample, can be checked. In order to check a large amount of active material, the sampling area should be greatly increased. However, the XRF analyzer is limited in setting resolution and scanning speed. Therefore, it takes a long time to scan a large area of ​​sample film at a set resolution and scanning speed. Therefore, this detection method is only suitable for experiments conducted at the laboratory level, and it is difficult to quickly check a large number of samples to meet the mass production environment of the factory.

[0010] [Related technical literature]

[0011] [Patent Document]

[0012] Korean Patent Publication No. 10-2014-0048370 Summary of the invention

[0013] Technical issues

[0014] In order to solve the above-mentioned problems, the present invention is directed to providing a foreign matter detection device and method for detecting foreign matter in an electrode active material with a high detection rate.

[0015] The present invention also aims to provide a foreign matter detection device and method for quickly inspecting a large amount of electrode active materials.

[0016] Technical Solution

[0017] One aspect of the present invention provides a device for detecting foreign matter in an electrode active material, the device comprising: a suspension tank containing a suspension in which the electrode active material is uniformly dispersed; a filter having a predetermined pore size, the filter being configured to filter the suspension transmitted from the suspension tank to collect foreign matter in the electrode active material; and an analyzer configured to analyze the filter that collects foreign matter to detect at least one of the type, total number, shape and size of the matter.

[0018] In one embodiment, the suspension tank may include a stirring member configured to stir and disperse the electrode active material and the foreign matter.

[0019] In one embodiment, the suspension may be delivered to the filter at a constant flow rate.

[0020] For example, the suspension may be transferred to and filtered by the filter while being sealed relative to the outside.

[0021] For example, the device may further include a foreign matter collection kit sealed relative to the outside in addition to the liquid inlet and the liquid outlet, and a filter may be installed in a communication passage between the liquid inlet and the liquid outlet.

[0022] The liquid inlet of the foreign body collection kit and the suspension tank can be connected by a gas-tight conduit.

[0023] In one embodiment, the device may further include a peristaltic pump installed in the sealed conduit between the suspension tank and the foreign matter collection kit to transfer the suspension at a constant flow rate.

[0024] The filter may be a polymer filter.

[0025] For example, the analyzer may be an X-ray fluorescence (XRF) analyzer configured to qualitatively and quantitatively analyze secondary X-rays generated for various types of foreign matter by emitting X-rays to a filter in which the foreign matter is collected.

[0026] The area of ​​the foreign matter collection region of the filter may be set to complete the X-ray scan by the XRF analyzer within a predetermined time and under the set resolution and scanning speed conditions of the XRF analyzer.

[0027] Another aspect of the present invention provides a method for detecting foreign matter in an electrode active material, the method comprising: preparing a suspension by suspending and stirring an electrode active material in a liquid, wherein the electrode active material is uniformly dispersed in the suspension; collecting foreign matter contained in the electrode active material in a filter having a predetermined pore size by passing the suspension through a filter; and analyzing the filter in which the foreign matter is collected to detect at least one of the type, total number, shape and size of the foreign matter.

[0028] The suspension can be transferred to the filter at a constant flow rate.

[0029] For example, the suspension may be transferred to and filtered by the filter while being sealed relative to the outside.

[0030] In the method, at least one of the type and total number of foreign matter may be detected by an XRF analyzer that qualitatively and quantitatively analyzes foreign matter from secondary X-rays generated for the type of foreign matter by emitting X-rays to a filter in which the foreign matter is collected.

[0031] In this method, the area of ​​the foreign matter collection region of the filter may be set to complete the X-ray scan by the XRF analyzer within a predetermined time and under the set resolution and scanning speed conditions of the XRF analyzer.

[0032] Beneficial effects

[0033] According to the present invention, foreign matter in an electrode active material can be detected with a high probability. That is, foreign matter in an electrode active material can be detected with a high detection rate (recovery rate).

[0034] According to the present invention, foreign matter can be detected by analyzing a large amount of electrode active material.

[0035] Furthermore, according to the present invention, by taking into account the resolution or scanning speed of the analyzer, the electrode active material can be analyzed in a short time, thereby quickly detecting foreign matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a schematic diagram of an apparatus for detecting foreign matter in an electrode active material according to a first embodiment of the present invention.

[0037] Figure 2 and Figure 3 are schematic diagrams and cross-sectional views of a foreign matter collection kit included in a foreign matter detection device.

[0038] Figure 4 and Figure 5 are schematic diagrams and cross-sectional views of another example of a foreign matter collecting kit included in a foreign matter detecting device.

[0039] Figure 6 Schematic diagram of the area of ​​the foreign matter collection region of the filter applied to the present invention.

[0040] Figure 7 is a schematic diagram of a state in which a filter is attached to a membrane to be inspected.

[0041] Figure 8 is a schematic diagram of an apparatus for detecting foreign matter in an electrode active material according to a second embodiment of the present invention.

[0042] Fig. 9 is a schematic diagram illustrating the operation of a peristaltic pump.

[0043] Fig.10 is a flow chart of a method for detecting foreign matter in an electrode active material according to the present invention.

[0044] Fig.11 This is a map of foreign matter obtained by an X-ray fluorescence (XRF) analyzer.

[0045] Fig.12 This is an image of a foreign object obtained through a microscope attached to an XRF analyzer.

[0046] Fig.13 is a graph showing the correlation between the amount of foreign matter powder and the number of foreign matter. DETAILED DESCRIPTION

[0047] Hereinafter, the present invention will be described in detail. Before describing the present invention, the terms or expressions used in this specification and claims should not be interpreted as limited to those defined in commonly understood or commonly used dictionaries, and should be understood based on the meaning and concept matching corresponding to the present invention, based on the inventor of the present application can appropriately define the terms or expressions to best explain the principle of the present invention.

[0048] It should be understood that the terms "include" and / or "comprising" when used herein specify the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, but do not exclude the presence or addition of one or more features, integers, steps, operations, elements, components, or combinations thereof. It should be understood that when an element or part is referred to as being "connected" to another element or part, the element or part is directly or indirectly connected to the other element or part.

[0049] As used herein, terms such as "on" or "below", "front" or "rear" or "positioned" or "arranged" are not intended to limit the invention and should be interpreted as providing examples of terms indicating position or orientation.

[0050] Hereinafter, the present invention will be described in detail.

[0051] <Foreign matter detection device>

[0052] (First embodiment)

[0053] Figure 1 is a schematic diagram of an apparatus for detecting foreign matter in an electrode active material according to a first embodiment of the present invention. Figure 2 and Figure 3 are schematic diagrams and cross-sectional views of a foreign matter collection kit included in a foreign matter detection device.

[0054] The foreign matter detection device 10 of the first embodiment of the present invention includes: a suspension tank 100, which contains a suspension L in which an electrode active material is uniformly dispersed; a filter 350, which has a predetermined pore size and is configured to filter the suspension L transmitted from the suspension tank 100 to collect foreign matter in the electrode active material; and an analyzer 400, which is configured to analyze the filter 350 in which the foreign matter is collected to detect at least one of the type, total number, shape and size of the foreign matter.

[0055] The electrode active material may include a positive electrode active material and a negative electrode active material. The positive electrode active material may be a lithium-containing oxide, and the lithium-containing oxide may be a lithium-containing transition metal oxide.

[0056] For example, the lithium-containing transition metal oxide may include one selected from the group consisting of: Li x CoO 2 (0.5 < x < 1.3), Li x NiO 2 (0.5 < x < 1.3), Li x MnO 2 (0.5 < x < 1.3), Li x Mn 2 O 4 (0.5 < x < 1.3), Li x (Ni a Co b Mn c )O 2 (0.5 < x < 1.3, 0 < a < 1, 0 < b < 1, 0 < c < 1, a + b + c = 1), Li x Ni 1-y Co y O 2 (0.5 < x < 1.3, 0 < y < 1), Li x Co 1-y Mn y O 2 (0.5 < x < 1.3, 0 ≤ y < 1), Li x Ni 1-y Mn y O 2 (0.5 < x < 1.3, 0 ≤ y < 1), Li x (Ni a Co b Mn c )O 4 (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 O 4 (0.5 < x < 1.3, 0 < z < 2), Li x Mn 2-z Co z O 4 (0.5 < x < 1.3, 0 < z < 2), Li x CoPO 4 (0.5 < x < 1.3) and Li x FePO 4(0.5 < x < 1.3), or a mixture of two or more of them. The lithium-containing transition metal oxide may be coated with a metal such as aluminum (Al) or a metal oxide. In addition to the lithium-containing transition metal oxide, at least one of sulfides, selenides, and halides may be used.

[0057] The negative electrode active material may include a carbon material, lithium metal, silicon, tin, etc. When a carbon material is used as the negative electrode active material, both low-crystalline carbon and high-crystalline carbon may be used. Representative examples of low-crystalline carbon include soft carbon and hard carbon, and representative examples of high-crystalline carbon include condensed graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, mesophase microspheres, mesophase pitch, and high-temperature calcined carbon such as coke derived from petroleum or coal pitch.

[0058] During the preparation of the active material, it is inevitable that foreign substances are mixed into the electrode active material. There are various types of metal foreign substances as representative examples of 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 a compound. The free metal elements remaining after the formation of the compound may be foreign substances that do not participate in the electroreaction. In particular, there are a large number of such metal foreign substances in the positive electrode active material. When a secondary battery is manufactured using an electrode containing foreign substances, unexpected defects such as low voltage defects may occur. The size of the foreign substance 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 pore size less than or equal to the size of the foreign substance. The electrode active material smaller than the foreign substance can be separated from the foreign substance when passing through the filter 350. The metal foreign substances can be adsorbed and collected by a magnetic member.

[0059] As described above, in the related art, foreign substances are detected by a dry method of preparing an electrode active material in powder form and filtering the electrode active material to detect metal foreign substance powder. However, in the related method, the foreign substance loss rate is high, so the foreign substance detection rate is very low. In addition, it is difficult to detect foreign substances by quickly inspecting a large amount of electrode active material to meet the mass production rate of secondary batteries.

[0060] In the present invention, foreign substances are detected by a so-called wet detection method of preparing a suspension L by suspending the electrode active material in a liquid and continuously passing the suspension L through a filter 350 to collect foreign substances.

[0061] 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.

[0062] The suspension L in which the electrode active material is uniformly dispersed is contained in the suspension tank 100. The suspension L is a mixture of suspensions in which small particles are not dissolved but are dispersed in the liquid like muddy water. That is, in the suspension L of the electrode active material, the active material and foreign matter contained in the active material are dispersed in the liquid in an undissolved state. Therefore, when the suspension L passes through the foreign matter collecting filter 350, the foreign matter can be collected in the filter 350.

[0063] Figure 1 A suspension tank 100 is shown, which includes a stirring member 110 to stir the electrode active material and foreign matter to uniformly disperse them.

[0064] The suspension tank 100 is a type of container in which the electrode active material is suspended and stirred in a liquid to uniformly disperse the electrode active material. Figure 1 In the embodiment, the stirring member 110 includes a rotating shaft rotated by a driving source (such as a motor not shown), and a stirring blade 111 coupled to the rotating shaft. However, the structure and shape of the stirring member 110 are not limited thereto, and other types of stirring members capable of properly stirring liquids may also be adopted.

[0065] The liquid in which the electrode active material is suspended may be a liquid in which the active material and foreign matter are not dissolved but the suspended matter can float in the liquid. For example, reverse osmosis (RO) water or deionized (DI) water may be used as the liquid of the suspension. RO water is pure water prepared by filtering salt from water by applying pressure through a reverse osmosis treatment device. DI water is water from which ions are removed using an ion exchange resin. That is, purified water obtained by removing impurities such as ions, solid particles, microorganisms, and organic materials from water may be used as the liquid of the suspension.

[0066] The suspension L in which the active material and foreign matter are uniformly dispersed can be obtained by stirring. Therefore, when the suspension L in which the sample is uniformly dispersed passes through the filter 350, a large amount of sample can be filtered without clogging the filter 350. In particular, by continuously transmitting the suspension to the filter 350 at a regular flow rate, a large amount of foreign matter can be stacked and collected by the filter 350 with a limited area. According to an example embodiment, according to the present invention, a large amount (e.g., 50 to 100g) of electrode active material can be analyzed. However, the amount of active material is not limited thereto. Compared with the method in the related art in which only about 10mg sampling can be performed, a large amount of active materials can be quickly analyzed according to the present invention, and the amount of these active materials is hundreds or thousands of times or more in the related art.

[0067] The filter 350 filters the suspension transmitted from the suspension tank 100, allowing small-sized active material particles to pass through and only collecting large-sized foreign matter. To this end, the filter 350 may have a pore size corresponding to the size of the foreign matter to be collected. For example, the filter 350 may have a pore size of 45 μm to collect metal foreign matter with a length or diameter of 45 μm or more. Alternatively, the filter 350 may have a pore size of 65 μm to collect metal foreign matter with a length or diameter of 65 μm or more.

[0068] The filter 350 may include a material suitable for filtering, such as nonwoven fabrics, polymers, or stainless steel. However, it may be desirable to use a filter of a material other than metal, since a metal filter may result in magnetic repulsion of metallic foreign matter having weak magnetic properties or paramagnetic properties. For example, a polyethylene (PE) filter may be used as a polymer filter.

[0069] In order to prevent contamination of the suspension, the suspension in the suspension tank 100 can be transferred to the filter 350 while being sealed relative to the outside. In addition, in order to prevent contamination from the outside during the filtering process, the filter 350 needs to be installed in an environment that is sealed relative to the outside.

[0070] To this end, the foreign matter detection device 10 of the present invention may include an airtight conduit 200 and a foreign matter collection kit 300 .

[0071] refer to Figure 1 , the airtight conduit 200 is connected between the suspension tank 100 and the foreign matter collection kit 300. A sealing member (e.g., an O-ring) may be installed at the connection portion between the airtight conduit 200 and the suspension tank 100 and at the connection portion between the airtight conduit 200 and the foreign matter collection kit 300. By preventing the suspension from leaking using the airtight conduit 200, an appropriate amount of the suspension may be transferred to the foreign matter collection kit 300. In addition, by preventing external air from flowing in through the airtight conduit 200, mixing of unnecessary bubbles that interfere with foreign matter collection may be prevented. A pump may be used to transfer the suspension from the suspension tank 100 to the filter 350 at a regular flow rate.

[0072] The airtight conduit 200 may be formed of a flexible material. For example, the airtight conduit 200 may be a tube or hose formed of a flexible plastic resin (e.g., polyurethane resin) or silicone resin. By bending the flexible hose, the transmission path of the suspension can be freely set between the suspension tank 100 and the filter 350.

[0073] The foreign matter collecting kit 300 is a type of filter fixing device configured to protect the filter 350 from the outside and fix the filter 350 at a predetermined position to collect foreign matter in a specific area of ​​the filter 350 .

[0074] refer to Figure 2 and Figure 3 , the foreign matter collection kit 300 includes a liquid inlet I1, a liquid outlet O2, and communication channels 313 and 323 connecting the liquid inlet I1 and the liquid outlet O2. The foreign matter collection kit 300 is configured to be sealed relative to the outside except for the liquid inlet I1 and the liquid outlet O2. Therefore, the filter 350 can stably collect foreign matter while being protected from the external environment in the foreign matter collection kit 300. The filter 350 is installed in the communication channels 313 and 323.

[0075] The liquid inlet I1 of the foreign matter collection kit 300 and the suspension tank 100 are connected through the airtight conduit 200. As described above, a sealing member such as an O-ring may be installed at a connection portion between the liquid inlet I1 and the airtight conduit 200.

[0076] refer to Figure 2 and Figure 3 The foreign matter collection kit 300 includes: an upper kit part 310, which includes a hollow body having a first hollow channel 313, and the two ends of the first hollow channel 313 are respectively opened toward the upper surface 311 and the lower surface 312 of the hollow body to form a first inlet I1 and a first outlet O1; and a lower kit part 320, which includes a hollow body having a second hollow channel 323, and the two ends of the second hollow channel 323 are respectively opened toward the upper surface 321 and the lower surface 322 of the hollow body to form a second inlet I2 and a second outlet O2. The first inlet I1 and the second outlet O2 correspond to the liquid inlet I1 and the liquid outlet O2 of the foreign matter collection kit 300, respectively. In addition, the first hollow channel 313 and the second hollow channel 323 are communication channels of the foreign matter collection kit 300.

[0077] The foreign matter collecting filter 350 may be fixed between the upper and lower kit parts 310 and 320 by combining the upper and lower kit parts 310 and 320 so that the first and second hollow passages 313 and 323 are concentrically disposed.

[0078] 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 airtight conduit 200 is connected to the first inlet I1 as a liquid injection port. Therefore, the suspension flowing into the airtight conduit 200 is transmitted to the filter 350 through the first inlet I1, the first hollow channel 313 and the first outlet O1. The liquid (mainly containing electrode active materials) filtered by the filter 350 is discharged downward through the second inlet I2, the second hollow channel 323 and the second outlet O2. As described above, the foreign matter collection kit 300 is configured to allow the suspension to pass from top to bottom so that the suspension can be smoothly filtered due to gravity. Considering the flow rate and speed of the suspension, the diameter and length of the first hollow channel 313 and the second hollow channel 323 can be appropriately determined. For example, the length of the entire communication channel including the first hollow channel 313 and the second hollow channel 323 can be determined to be within the range of 45mm to 70mm, but is not limited thereto. Therefore, the total height of the foreign matter collection kit 300 including the upper kit part 310 and the lower kit part 320 may be determined to be within the range of 45 mm to 70 mm, but is not limited thereto.

[0079] The diameters of the first inlet I1, the first hollow channel 313 and the first outlet O1 and the diameters of the second inlet I2, the second hollow channel 323 and the second outlet O2 may be the same. However, as described below, the diameters of the first hollow channel 313 and the second hollow channel 323 may vary in the height direction.

[0080] Figure 2 The diameter of the foreign body collection kit is shown 1. The diameter of the filter and filter mounting groove installed in the foreign matter collection kit 2. The diameters of the first hollow channel, the second hollow channel and the foreign matter collection area 3.

[0081] In example embodiments, the upper kit part 310 and the lower kit part 320 may be coupled by fitting or threading. For example, the fitting protrusion 312a may be provided on one of the opposing surfaces of the upper kit part 310 and the lower kit part 320, the insertion groove 321a may be provided in the other surface, and the upper kit part 310 and the lower kit part 320 may be coupled to each other by inserting the fitting protrusion 312a into the insertion groove 321a (see Figure 2 and Figure 3 ). Alternatively, threads A1 and A2 that interlock with each other are provided on opposing surfaces of the upper and lower kit parts 310 and 320, and thus, the upper and lower kit parts 310 and 320 may be threadedly coupled to each other (see Figure 4 and Figure 5Here, the opposing surfaces of the upper and lower sets 310 and 320 may be horizontal surfaces. Alternatively, as Figure 4 and Figure 5 As shown, when there is a step on the opposing surfaces of the upper and lower sleeve parts 310 and 320, the opposing surfaces may be a vertical surface that is a part of the step surface. Figure 4 and Figure 5 As shown, the upper kit part 310 and the lower kit part 320 can be threadedly coupled to each other by providing threads A1 and A2 interlocking with each other on the opposing vertical surfaces of the upper kit part 310 and the lower kit part 320. Since the upper kit part 310 and the lower kit part 320 are coupled and the filter 350 is exposed only in the suspension penetration area (the first hollow channel 313 and the second hollow channel 323), foreign matter is collected only in the suspension penetration area. In addition, the upper kit part 310 and the lower kit part 320 are firmly coupled by threads or the like, so foreign matter does not spread outside the penetration area of ​​the filter 350.

[0082] The filter 350 may be concentrically installed between the first outlet O1 and the second inlet I2 to completely cover the first outlet O1 and the second inlet I2. In this case, the area of ​​the foreign matter collection region 351 of the filter 350 is the same as that of the first outlet O1 and the second inlet I2.

[0083] The receiving groove for accommodating 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, the filter receiving groove 321b may be provided only in the upper surface 321 of the lower kit part 320, and the lower surface 312 of the upper kit part 310 opposite to the upper surface 321 may be a flat surface covering only the filter 350. Conversely, the filter receiving groove 312b may be provided only in the lower surface 312 of the upper kit part 310, and the upper surface 321 of the lower kit part 320 opposite to the lower surface 312 may be a flat surface covering only the filter 350. Alternatively, as Figure 3 As shown, grooves 312b and 321b for accommodating the filter 350 may be provided in both the lower surface 312 of the upper kit part 310 and the upper surface 321 of the lower kit part 320. Due to the presence of such receiving grooves, the filter 350 may be stably placed between the upper kit part 310 and the lower kit part 320, and fixed in the receiving groove without moving when the upper kit part 310 and the lower kit part 320 are coupled to each other.

[0084] As another example, Figure 5As shown, a receiving groove 321b for accommodating the filter 350 may be provided in 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 protrusion covering part 312P configured to cover the filter 350 when inserted into the receiving groove 321b may be provided on the other upper surface 321 or the lower surface 312. In this case, when the upper kit part 310 and the lower kit part 320 are coupled to each other, the filter 350 may be stably fixed and held in the gap between the receiving groove 321b and the protrusion covering part 312P.

[0085] The material of the foreign matter collection kit 300 may be a material having high chemical resistance, high wear resistance, and high strength. For example, the foreign matter collection kit 300 may be formed of polyetheretherketone (PEEK) having high chemical resistance and strength.

[0086] Figure 4 and Figure 5 1 is a schematic diagram and a cross-sectional view of another example of a foreign matter collecting kit 300 ′ included in the foreign matter detecting device 10 .

[0087] An injection tube 314 that is in communication with the first hollow channel 313 and extends upward is provided on the upper surface 311 of the upper kit portion 310 of the foreign matter collection kit 300'. The injection tube 314 protrudes upward and is therefore easily connected to the airtight conduit 200 as described above. For example, the injection tube 314 can be tightly fitted to a polyurethane hose to maintain a sealed state, and the airtight conduit 200 is connected to the foreign matter collection kit 300'. In addition, the injection tube 314 of a predetermined length protrudes and is inserted into the airtight conduit 200 with a predetermined length, thereby preventing the risk of leakage of the suspension. In addition, the injection tube 314 extending upward serves as a funnel, thereby facilitating the injection of the suspension into the foreign matter collection kit 300' through the inlet I1' of the injection tube 314.

[0088] exist Figure 3 In the example, the first hollow channel 313 and the second hollow channel 323 have the same diameter 3. However, the diameter of the hollow channel may be changed according to its height to facilitate the flow of the suspension and the discharge of the liquid passing through the filter 350. For example, the bottom of at least one of the first hollow channel 313 and the second hollow channel 323 may be provided with a tapered channel portion 313b and 323b whose channel cross-sectional area increases toward the outlet of each of the first hollow channel 313 and the second hollow channel 323.

[0089] like Figure 5As shown, the first hollow channel 313 may include an upper channel 313a having a constant diameter and a lower channel 313b having a variable diameter. The upper channel 313a is connected to the above-mentioned injection pipe 314. The diameter of the upper channel 313a is set to be the same as the inner diameter of the injection pipe 314 to ensure a stable downward flow of the suspension. At the same time, the lower channel 313b connected to the upper channel 313a has a conical shape, and its cross-sectional area gradually increases toward the first outlet O1. That is, the lower channel 313b is a conical channel portion 313b. Therefore, the suspension flowing downward can be introduced into the filter 350 more smoothly and at a higher flow rate. In this case, the second inlet I2, the second hollow channel 323 and the second outlet O2 of the lower kit part 320 can be as shown. Figure 3 However, in this case, the diameter of the second inlet I2, etc. may be set to be the same as the diameter of the first outlet O1 of the expanded tapered passage portion 313b.

[0090] Alternatively, if Figure 5 As shown, the second hollow channel 323 may include an upper channel 323a having a constant diameter and a lower channel 323b having 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 to ensure the stable downward flow of the suspension. At the same time, the lower channel 323b connected to the upper channel 323a has a tapered shape, and its cross-sectional area gradually increases toward the second outlet O2. That is, the lower channel 323b is a tapered channel portion 323b. Therefore, the filtered suspension containing the active material can be discharged more smoothly and at a higher flow rate.

[0091] Figure 5 An example is shown in which both the first hollow channel 313 and the second hollow channel 323 include the tapered channel portion, but only one of the first hollow channel 313 and the second hollow channel 323 may include the tapered channel portion.

[0092] Figure 4 and Figure 5The foreign matter collection kit 300' includes a plurality of step portions S11, S12, S21 and S22 on the opposing surfaces of the upper kit portion 310 and the lower kit portion 320. By combining the step portions S11, S12, S21 and S22, the upper kit portion 310 and the lower kit portion 320 can be more firmly coupled, and the filter 350 can be more firmly fixed between the upper kit portion 310 and the lower kit portion 320. The upper kit portion 310 includes two step portions on the lower surface 312, so that its horizontal surface facing the lower kit portion 320 is divided into three horizontal surfaces 312-1, 312-2 and 312-3. In addition, the lower kit portion 320 includes two step portions on the upper surface 321, so that its horizontal end surface facing the upper kit portion 310 is divided into three horizontal surfaces 321-1, 321-2 and 321-3. A vertical surface is provided between adjacent horizontal surfaces among the three horizontal surfaces.

[0093] Referring to the drawings, the first lower surface step portion S11 is disposed on the outer side of the lower surface 312 of the upper set portion 310. In addition, the first upper surface step portion S21 having a shape interlocked with the first lower surface step portion S11 is disposed on the outer side of the upper surface 321 of the lower set portion 320. The first lower surface step portion S11 includes two horizontal surfaces 312-1 and 312-2 and a vertical surface therebetween, and the first upper surface step portion S22 includes two horizontal surfaces 321-1 and 321-2 and a vertical surface therebetween. In this case, the opposing vertical surfaces of the first lower surface step portion S11 and the first upper surface step portion S21 may be provided with threads A1 and A2 to interlock with each other, thereby being threadedly coupled to each other. The vertical length of the threaded portion on the vertical surface is determined by the distance that the upper set portion 310 moves downward according to the threaded coupling. As described below, the upper set portion 310 and the lower set portion 320 are coupled to each other so that the second lower surface step portion S12 and the second upper surface step portion S22 are interlocked with each other. In this case, when the second lower surface step portion S12 is in very close contact with the second upper surface step portion S22 and thus the second upper surface step portion S22 is pressurized, the filter 350 between the second lower surface step portion S12 and the second upper surface step portion S22 may be damaged. Therefore, the vertical length of the threaded portion is preferably set to be the same as the distance the upper sleeve portion 310 moves downward and the distance the second lower surface step portion S12 moves downward when the threaded connection is performed, thereby preventing the filter 350 from being over-pressurized.

[0094] The second lower surface step portion S12 connected to the first lower surface step portion S11 is disposed on the inner side of the lower surface 312 of the upper set portion 310. The second upper surface step portion S22 connected to the first upper surface step portion S21 and interlocked in shape with the second lower surface step portion S12 is disposed on the inner side of the upper surface 321 of the lower set portion 320. The filter 350 is installed between the second upper surface step portion S22 and the opposing horizontal surfaces 312-3 and 321-3 of the second lower surface step portion S12. The side surface of the filter 350 is adjusted by the vertical surface of the second upper surface step portion S22 to prevent the filter 350 from moving. When the upper set portion 310 and the lower set portion 320 are threadedly coupled to each other, the filter 350 is supported and fixed between the horizontal surfaces of the second lower surface step portion S12 and the second upper surface step portion S22 and supported and fixed by the vertical surface of the second upper surface step portion S22. Therefore, even when pressure is applied due to the downward flow of the suspension, the filter 350 can continuously filter foreign materials while being stably maintained.

[0095] For example, a filter seating sheet 360 coupled to the filter 350 while surrounding the filter 350 may be further provided and fixedly installed between the upper and lower kit parts 310 and 320 .

[0096] The area of ​​the foreign matter collection region 351 of the filter 350 may be set to an area that will be scanned by X-rays within a predetermined time according to the set resolution and scanning speed of the analyzer 400 that analyzes foreign matter by X-ray scanning.

[0097] Figure 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 Figure 7 is a schematic diagram showing a state in which the filter 350 is attached to a membrane to be inspected.

[0098] Conventionally, a dry method of filtering active material powder containing foreign matter using air pressure is adopted, and therefore, the foreign matter is spread over a wide area due to the air pressure, making it impossible to increase the collection density of the foreign matter. Therefore, it is necessary to perform the troublesome task of attaching the tape multiple times to collect the foreign matter. In this process, the loss rate of the foreign matter is high, and thus the efficiency of collecting and detecting the foreign matter is low. In addition, the foreign matter is detected together with the active material, and therefore it is difficult to detect with a narrow X-ray scanning area.

[0099] In contrast, according to the present invention, foreign matter is uniformly dispersed in the suspension tank 100 to prepare a suspension, and the suspension is continuously supplied to the filter 350, thereby helping to minimize the area of ​​the foreign matter collection region 351 of the filter 350. That is, the foreign matter is uniformly dispersed without being unevenly distributed in the suspension, thereby preventing the filter 350 from being clogged during filtration. In addition, the suspension in which the foreign matter is uniformly dispersed can be continuously supplied to the filter 350 having a pore size, thereby enabling filtering of the foreign matter so that only the foreign matter can be collected in the filter 350 in a concentrated manner. By collecting foreign matter by the wet method or the wet pretreatment method as described above, the foreign matter can be collected in a small area in a concentrated manner.

[0100] refer to Figure 6 (a), the small center circle in the large outer circle represents the boundary of the area where the filter 350 collects foreign matter. It can be seen that the diameter of the small center circle is 3 Much smaller than the diameter of the larger outer circle 2. Diameter of the center circle 3 and the diameter of the first outlet O1 of the upper sleeve part 310 and the second inlet I2 of the lower sleeve part 320 3. In an exemplary embodiment, the diameter of the center circle may be approximately 1 to 2 cm. However, the diameter 3 and the area of ​​the foreign matter collection area 351 are not limited thereto, and may be increased or decreased according to the resolution and scanning speed of the analyzer 400. As described above, even at a limited scanning speed, foreign matter can be quickly inspected by scanning a circle having a small area with X-rays. In addition, a large amount of active materials can be quickly inspected while satisfying a set resolution. As described above, according to the present invention, filtering may be performed by only a portion of the filter 350, rather than by the entire filter 350. The remaining portion of the filter 350 that is not used for filtering is fixed between the upper kit portion 310 and the lower kit portion 320.

[0101] According to the present invention, since the area of ​​the foreign matter collection area 351 can be minimized, the area of ​​the filter 350 can be reduced to match the area of ​​the foreign matter collection area 351. Figure 6 As shown in (b), in an exemplary embodiment, a filter placement sheet 360 may be provided which is coupled to the filter 350 having a small area while surrounding the filter 350. The filter placement sheet 360 is a support sheet to which the filter 350 is coupled and placed. When the filter placement sheet 360 is fixedly installed between the upper kit part 310 and the lower kit part 320, the filter 350 may be accurately positioned at a filtering position through which the suspension passes. In this case, the diameter of the filter 350 may be equal to or slightly larger than the diameter of the first outlet O1 of the upper kit part 310 and the second inlet I2 of the lower kit part 320. 3.

[0102] Figure 7 4 is a schematic diagram showing a state where the filter 350 is attached to the membrane F to be inspected. In order to perform inspection using the analyzer 400, the filter 350 may be attached to the membrane F to be inspected, and the membrane F may be analyzed by placing the membrane F into the analyzer 400. Figure 7 As shown, a small central circular portion of the filter 350 may be scanned rather than scanning the entire area of ​​the filter 350, thereby greatly improving inspection speed and efficiency.

[0103] According to the present invention, an analyzer 400 is provided, which analyzes the filter 350 in which foreign matter is collected to detect at least one of the type, total number, shape and size of the foreign matter. As described above, according to the present invention, target foreign matter can be stacked and collected in a small area. Therefore, it can be expected that the foreign matter detection efficiency will be significantly improved regardless of the type of the analyzer 400.

[0104] An X-ray fluorescence (XRF) analyzer may be used as the analyzer 400. XRF analysis is a method of analyzing a sample to be inspected by analyzing secondary fluorescent X-rays generated inside a sample when X-rays are emitted to the sample (or the sample is scanned by X-rays). Using the XRF analyzer 400, X-rays may be emitted to the filter 350 in which foreign matter is collected to qualitatively and quantitatively analyze the foreign matter based on the secondary fluorescent X-rays generated according to the type of the foreign matter. Fluorescent X-rays have different wavelengths and energies for each element. Therefore, the type of foreign matter may be identified by qualitative analysis based on the wavelength or energy of the secondary fluorescent X-rays.

[0105] In addition, the elements of foreign matter or the number of foreign matter can be identified based on the results of mapping analysis obtained based on a two-dimensional (2D) image obtained by X-ray scanning. For example, by emitting X-rays to the foreign matter collection area 351 to scan the foreign matter collection area 351, a map in which pixels are colored can be obtained. The number of foreign matter can also be identified by software using an algorithm that converts the coloring in the map into counts. Therefore, foreign matter in the electrode active material can be quantitatively analyzed.

[0106] Meanwhile, the shape and size of foreign matter can be identified using an optical microscope or an electron microscope such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM). Recently, an analyzer in which a microscope device such as an SEM is integrated into the XRF analyzer 400 has been released. Therefore, all of the types, total numbers, shapes, and sizes of foreign matter can be identified by such an analyzer. It is important to increase the degree of integration for collecting foreign matter and minimize the area of ​​the foreign matter collection area 351 to improve foreign matter detection efficiency regardless of the type of analyzer to be used, and the present invention is intended to achieve these tasks.

[0107] The foreign matter detection device 10 of the present invention can set the area of ​​the foreign matter collection region 351 of the filter 350 so that the X-ray scanning performed by the XRF analyzer 400 can be completed within a predetermined time under the set resolution and scanning speed conditions of the XRF analyzer 400. Figure 6 As shown, the area of ​​the foreign matter collection region 351 can be set to be small, and when the small area is scanned at a predetermined resolution and scanning speed using the XRF analyzer 400, the analysis can be completed within a few minutes to several tens of minutes (e.g., a few minutes to thirty minutes). Therefore, even when the above-mentioned suspension and filtration time is included, it takes less than an hour to perform one analysis, and a specific batch of electrode active materials can be quickly checked during mass production, thereby facilitating mass production.

[0108] Meanwhile, the shape of the foreign matter collecting area 351 is not limited to Figure 6 The circle shown.

[0109] That is, when the shapes of the first inlet I1 , the first hollow channel 313 , and the first outlet O1 are changed to a rectangle, an ellipse, or other shapes, the shape of the foreign matter collection area 351 may be changed to a rectangle, an ellipse, or other shapes.

[0110] The shapes of the second inlet 12, the second hollow channel 323 and the second outlet O2 may also be changed to rectangular, elliptical or other shapes.

[0111] (Second embodiment)

[0112] Figure 8 is a schematic diagram of a device 20 capable of detecting foreign matter in an electrode active material according to a second embodiment of the present invention, and Fig. 9 2 is a schematic diagram showing the operation of the peristaltic pump. The second embodiment will be described below focusing on the differences from the first embodiment.

[0113] As with the first embodiment, the foreign matter detection device 20 of the second embodiment includes a suspension tank 100, a foreign matter collection kit 300, and an analyzer 400. The second embodiment differs from the first embodiment in that a peristaltic pump 500 capable of transferring the suspension to the foreign matter collection kit 300 at a constant flow rate is further provided. Figure 8 The peristaltic pump 500 is installed in the airtight conduit 200 between the suspension tank 100 and the foreign matter collection kit 300 to transfer the suspension at a constant flow rate.

[0114] When the flow rate of the suspension transferred from the suspension tank 100 to the filter 350 varies greatly, the pores of the filter 350 may be clogged due to locally concentrated foreign matter when filtering is performed through the filter 350. Therefore, if possible, the suspension needs to be transferred to the filter 350 at a constant flow rate.

[0115] Peristaltic pump 500 is a positive displacement pump and is designed based on the principle of peristalsis. The term "peristalsis" means a series of muscle contractions by which food moves to different parts along the digestive organs. Peristaltic pump 500 moves fluid in a manner similar to the action of the digestive organs.

[0116] refer to Fig. 9 The peristaltic pump 500 includes a pump body 510 and a rotating member 520, wherein the pump body 510 includes a space 511 for accommodating a fluid (suspension) conduit 200 therein, and the rotating member 520 is accommodated in the space 511. The rotating member 520 is rotated by a driving source such as a motor and includes a roller or a shoe 521. A portion 210 of the airtight conduit 200 is disposed in the space 511 along the inner surface of the pump body 510. Fig. 9 As shown, the shoes 521 are installed at both ends of the rotating member 520 , 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 .

[0117] When using the peristaltic pump 500, only the tube (hose) is in contact with the fluid, thereby preventing the pump from being contaminated by the suspension, or the suspension from being contaminated by the pump. In addition, when the pump is not in use, backflow is prevented and a check valve is not required.

[0118] <Foreign matter detection method>

[0119] Fig.10 is a flow chart of a method for detecting foreign matter in an electrode active material according to the present invention.

[0120] The method for detecting foreign matter according to the present invention may include: preparing a suspension in which an electrode active material is uniformly dispersed by suspending and stirring the electrode active material in a liquid (S1); collecting foreign matter contained in the electrode active material in a filter having a predetermined pore size by passing the suspension through the filter (S3); and analyzing the filter in which the foreign matter is collected to detect at least one of the type, total number, shape and size of the foreign matter (S4).

[0121] For example, foreign matter can be Figure 1 or Figure 8 The foreign object detection device 10 or 20 shown detects.

[0122] First, the electrode active material is suspended and stirred in a liquid such as DI water or RO water. A positive electrode active material or a negative electrode active material can be used as the electrode active material. The method of this embodiment will be described with respect to filtering out metal foreign matter greater than or equal to a specific size from the positive electrode active material. For example, a large amount (e.g., 50 g) of the positive electrode active material is suspended in 1 L of DI water. The suspension can be prepared by stirring the active material in a suspension tank for 5 to 10 minutes so that the active material is evenly dispersed in the liquid.

[0123] The method for detecting foreign matter according to the present invention may further include transferring the suspension to the filter at a constant flow rate (S2). In this case, an airtight conduit may be used to transfer the suspension while being sealed relative to the outside. For example, a silicone tube (hose) or a polyurethane tube (hose) may be used as the airtight conduit. In order to transfer the suspension at a constant flow rate, Fig. 9 The peristaltic pump 500 can be installed between the suspension tank and the foreign matter collection kit on the airtight conduit. For example, the suspension can be transferred from the suspension tank to the foreign matter collection kit 300 at a flow rate of 500 ml / min to 1000 ml / min by the peristaltic pump 500.

[0124] When filter 350 is installed Figure 2 and Figure 4 When the filter 350 is in the foreign matter collection kit 300, filtering can be performed in an environment protected from external influences. For example, the filter 350 can be positioned between the upper kit part 310 and the lower kit part 320, and combined to fix the filter 350 between the upper kit part 310 and the lower kit part 320. When the remaining portion (or Figure 6 When the filter placement sheet 360 is placed in the receiving groove and the upper set portion 310 and the lower set portion 320 are coupled to each other, foreign matter can be prevented from being scattered outside the foreign matter collection area 351. That is, the foreign matter collection area 351 can be limited to the area where the suspension penetrates.

[0125] Furthermore, the foreign matter collection kit 300 is sealed except for an upper inlet (first inlet I1 ) of the upper kit part 310 and a lower outlet (second outlet O2 ) of the lower kit part 320 , thereby preventing contamination of the filter 350 and the like.

[0126] For example, in order to collect foreign matter with a size of 40 to 65 μm, a filter 350 with a pore size corresponding to the size of the foreign matter can be used. For example, a polymer filter with a pore size of 40 μm can be used. The foreign matter in the electrode active material is collected in the filter 350 by passing the suspension through the filter 350 (S3). When the peristaltic pump completes the suction of the suspension, the filtered liquid is fully discharged for a predetermined time period (for example, one minute) through the connecting pipe connected to the first outlet O1. By discharging the filtrate within this time period, it can be ensured that the filter 350 has enough time to fully filter out the foreign matter.

[0127] After the filtering is completed, the filter 350 in which the foreign matter is collected is analyzed to detect at least one of the type, total number, shape, and size of the foreign matter ( S4 ).

[0128] After the filtration is completed, the foreign matter collection kit 300 is disassembled to recover the filter 350. In order to check, Figure 7 As shown, the filter 350 may be attached to the membrane F to be inspected, and the membrane F may be placed into the analyzer 400 to perform the analysis.

[0129] The XRF analyzer 400 may be used to analyze foreign matter. The XRF analyzer 400 may emit X-rays to the filter 350, and qualitatively and quantitatively analyze the foreign matter based on secondary X-rays generated according to the type of foreign matter. At least one of the type and amount of foreign matter may be detected by the XRF analyzer 400. In addition, the shape and size of the foreign matter may be detected by a microscope attached to the XRF analyzer 400 or the additional analyzer 400.

[0130] As described above, according to the present invention, the area of ​​the foreign matter collection area 351 of the filter 350 can be minimized using wet pretreatment and filtration. In order to obtain a high-resolution image to be detected, the resolution of the XRF analyzer 400 is set within a predetermined range. In addition, the scanning speed of the XRF analyzer 400 is determined. When the area of ​​the foreign matter collection area 351 is small, the X-ray scanning can be completed in a short time under the set resolution and scanning speed conditions. Therefore, according to the foreign matter detection method of the present invention, the analysis speed of the XRF analyzer 400 can be improved and the analysis time can be reduced.

[0131] For example, it takes about 5-10 minutes to prepare the suspension and perform the filtration pretreatment, and the XRF analysis can be performed within 30 minutes. For example, a large amount (e.g., about 100 g) of electrode active material can be analyzed. About 100 g of active material can represent an intermediate product (batch). According to the present invention, the detection time can be reduced to check about 80 to 100 batches per day, thereby meeting the desired electrode and battery mass production rate.

[0132] In addition, according to the present disclosure, the collection efficiency can be improved to achieve a very high foreign matter detection rate. Therefore, the type, quantity, shape and size of foreign matter in the electrode active material can be detected with a high probability. Therefore, the quality of the electrode active material can be evaluated. For example, it can be determined whether the electrode active material is suitable based on the type and quantity of foreign matter. When the quality of the electrode active material is evaluated as described above, and the battery is manufactured with a suitable electrode active material, the defective battery cell rate can be greatly reduced.

[0133] Therefore, another aspect of the present invention may provide a secondary battery manufacturing method, which includes evaluating the quality of an electrode active material according to a result of detecting foreign matter by a foreign matter detection method, and manufacturing a battery using the electrode active material selected according to the evaluation result.

[0134] Fig.11 This is a map of various foreign matter obtained by XRF analyzer.

[0135] The 2D image obtained from the wavelength of the secondary fluorescence X-ray is obtained by software conversion. Fig.11 From Fig.11 It can be seen that, depending on the wavelength, various types of metallic foreign matter such as Fe, Cr, Cu, Zn, Mn, Co, Ni, and Ti are present in the positive electrode active material (see Fig.11 (a)). As described above, the type of foreign matter can be identified by the XRF analyzer 400. Fig.11 (b) is an enlarged view of the Fe mapping.

[0136] Fig.12 is an image of a foreign object obtained by a microscope attached to the XRF analyzer 400. The shape and size of the foreign object can be calculated from the image of the foreign object. The size of the foreign object can be measured by comparing the size of the image with the size of the shape of the foreign object. A calculation program can be used in this case.

[0137] The process of detecting the number of foreign objects according to the present invention will be described with reference to the following examples.

[0138] [Embodiments of the Invention]

[0139] <Example>

[0140] 100 g of NCM-based cathode active material powder was suspended in 1 L of DI water while varying the amount of foreign matter (Cu) and Figure 1The suspension 100 was stirred for 8 minutes to prepare a positive active material suspension. Pressure was applied to the suspension by a peristaltic pump to transfer the suspension to a PEEK foreign matter collection kit at a flow rate of 500 ml / min. After the suction of the suspension was completed, the filtrate was discharged for 60 seconds through a silicone tube connected to the lower part of the foreign matter collection kit. A polyethylene filter with a pore size of 40 μm was used. A 15 mm×15 mm rectangular tube was used as the first hollow channel 313, thereby minimizing the area of ​​the foreign matter collection area 351 to 15 mm×15 mm.

[0141] The foreign matter collection kit was disassembled, and the filter was analyzed by placing it in an XRF FID analyzer (EA8000, manufactured by Hitachi Co., Ltd.) while attached to the membrane to be inspected.

[0142] X-rays were emitted from the XRF analyzer to a scanning size of 15 mm × 15 mm by a mapping scanning method. The resolution was set to 30 μm / pixel, and the scanning speed was set to 5 ms.

[0143] Fig.13 is a graph showing the correlation between the amount of foreign matter powder and the number of foreign matter.

[0144] Fig.13 The correlation between the weight and quantity of copper is shown. Correlation indicates that there is a certain relationship between two variables, and a correlation coefficient representing a measure of the correlation can be calculated. The statistical method of calculating the correlation coefficient from two variable data is well known, so its detailed description is omitted here.

[0145] Fig.13 The correlation coefficient between the amount and weight of copper contained in the same type of positive electrode active material as the NCM-based positive electrode active material used for XRF analysis is shown. Fig.13 As shown, the correlation coefficient is 0.9976 which is almost close to 1. Therefore, it can be estimated that 2338 Cu powders are contained in 0.003 g of Cu.

[0146] [Table 1]

[0147] As can be seen from Table 1, the median particle size D50 of the positive electrode active material is 10.2 to 11.6 μm, and its maximum particle size is 27.5 μm, so the positive electrode active material is discharged through the filter. The copper amounts in Experimental Examples 1-3 are 2050, 2164, and 2341. In order to compare the copper amounts under the same standard, they are converted to 1809, 1967, and 2066 based on 0.003 g of Cu.

[0148] refer to Fig.13, 2338 powders are contained in 0.003 g of Cu, so in Examples 1 to 3, the foreign matter detection rates, that is, the recovery rates of foreign matter recovered from the injected foreign matter, are 77%, 84%, and 88%, respectively.

[0149] Therefore, according to the foreign matter detection method of the present invention, foreign matter can be detected with a high probability of 83% on average.

[0150] As described above, according to the foreign matter detection device and method of the present invention, foreign matter in the electrode active material can be detected quickly with a high probability, thereby greatly improving the detection reliability.

[0151] The above description is merely an example of the technical concept of the present invention, and various modifications and changes may be made by those skilled in the art without departing from the basic characteristics of the present invention.

[0152] Therefore, the drawings of the present invention set forth herein are not intended to limit the technical concept of the present invention, but are intended to describe the technical concept, and the scope of the technical concept of the present invention is not limited by the drawings. The protection scope of the present invention should be interpreted based on the attached claims, and all technical concepts within the same scope as the present invention should be interpreted as included within the scope of the present invention.

[0153] (reference numerals)

[0154] 10, 20: Foreign matter detection device

[0155] 100: Suspension tank

[0156] L: Suspension

[0157] 110: Mixing member

[0158] 200: Airtight catheter

[0159] 300, 300': Foreign matter collection kit

[0160] 310 upper kit part

[0161] 320: Lower kit part

[0162] 350: Filter

[0163] 351: Foreign matter collection area

[0164] 360: Filter placement sheet

[0165] 400: (XRF) Analyzer

[0166] F: Membrane to be inspected

[0167] 500: Peristaltic pump

Claims

1. A device for detecting foreign matter in an electrode active material, the device comprising: A suspension tank, the suspension tank containing a suspension in which an electrode active material is uniformly dispersed; a filter having a predetermined pore size and configured to filter the suspension transferred from the suspension tank to collect foreign matter in the electrode active material; as well as An analyzer configured to analyze the filter in which the foreign matter is collected to detect at least one of the type, total number, shape and size of the foreign matter.

2. The device according to claim 1, wherein: The suspension tank includes a stirring member configured to stir and disperse the electrode active material and the foreign matter.

3. The device according to claim 1, wherein: The suspension is transferred to the filter at a constant flow rate.

4. The device according to claim 1, wherein: The suspension is transferred to the filter while being sealed from the outside, and is filtered by the filter.

5. The device according to claim 1, further comprising a foreign matter collection kit, the foreign matter collection kit comprising a liquid inlet, a liquid outlet, and a communication channel, the communication channel connecting the liquid inlet and the liquid outlet, the foreign matter collection kit being sealed relative to the outside except for the liquid inlet and the liquid outlet, in, The filter is installed in the communication passage.

6. The device according to claim 5, wherein: The liquid inlet of the foreign matter collection kit is connected to the suspension tank through an airtight conduit. 7 . The apparatus according to claim 6 , further comprising a peristaltic pump installed in the sealed conduit between the suspension tank and the foreign matter collection kit to transfer the suspension at a constant flow rate.

8. The device according to claim 1, wherein: The filter comprises a polymer filter.

9. The device according to claim 1, wherein: The analyzer includes an X-ray fluorescence (XRF) analyzer configured to qualitatively and quantitatively analyze the foreign matter according to secondary X-rays generated for a type of the foreign matter by emitting X-rays to the filter in which the foreign matter is collected.

10. The device according to claim 9, wherein: The area of ​​the foreign matter collection region of the filter is set to complete an X-ray scan by the XRF analyzer under set resolution and scanning speed conditions of the XRF analyzer within a predetermined time.

11. A method for detecting foreign matter in an electrode active material, the method comprising: preparing a suspension by suspending an electrode active material in a liquid and stirring the suspension, wherein the electrode active material is uniformly dispersed in the suspension; collecting foreign matter contained in the electrode active material in the filter by passing the suspension through a filter having a predetermined pore size; and The filter having the foreign matter collected therein is analyzed to detect at least one of the type, total number, shape, and size of the foreign matter.

12. The method according to claim 11, wherein: The suspension is transferred to the filter at a constant flow rate.

13. The method according to claim 11, wherein: The suspension is transferred to the filter while being sealed from the outside and filtered by the filter.

14. The method according to claim 11, wherein: At least one of the type and total number of the foreign matter is detected by an X-ray fluorescence (XRF) analyzer that qualitatively and quantitatively analyzes the foreign matter according to secondary X-rays generated for the type of the foreign matter by emitting X-rays to the filter in which the foreign matter is collected.

15. The method according to claim 14, wherein: The area of ​​the foreign matter collection region of the filter is set to complete an X-ray scan by the XRF analyzer under set resolution and scanning speed conditions of the XRF analyzer within a predetermined time.

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