Foreign Substance Collection Kit for Electrode Active Material

Abstract

The disclosed invention provides a foreign matter collection kit for an electrode active material, including: a hollow main body portion having a first hollow channel, both ends of the first hollow channel being respectively opened on the upper surface and the lower surface of the hollow main body portion to form a first inlet and a first outlet, an upper kit portion; a lower kit portion having a hollow main body portion with a second hollow channel, both ends of the second hollow channel being respectively opened on the upper surface and the lower surface of the hollow main body portion to form a second inlet and a second outlet; and a foreign matter collection filter fixed between the upper kit portion and the lower kit portion by connecting the upper kit portion and the lower kit portion so that the first hollow channel and the second hollow channel are concentrically arranged, the foreign matter collection filter having a predetermined pore size.

Description

Technical Field

[0001] The present invention relates to a foreign matter collection kit.

[0002] More specifically, it relates to a foreign matter collection kit for collecting foreign matters contained in an electrode active material.

[0003] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0026229 filed on February 27, 2023, and all the 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 matters. Foreign matters 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 components, number, shape, and size of foreign matters in the electrode active material to grasp which foreign matters affect the characteristics of the secondary battery. For this purpose, it is necessary to collect and detect the foreign matters 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 an active material, there is a method of filtering electrode active material powder by applying air pressure above and below a metal filter. The active material powder 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 collecting the foreign substance. Since the foreign substance is sparsely collected on the filter with a large area, 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 components of the foreign substance and the like.

[0008] However, in such a method, a large amount of foreign substances are lost in 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, there are cases where foreign substances with weak magnetism or paramagnetism are not properly adsorbed onto 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 the electrode active material powder containing foreign substances on a film and analyzing it with an analyzer. However, in this case, since the 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. For a large amount 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 level of experiments in a laboratory, and it has been difficult to quickly inspect a large amount of samples to meet the mass production environment of a factory.

[0010] Instead of detecting foreign matter in the conventional dry method, if an electrode active material containing foreign matter is manufactured as a suspension and the suspension is passed through a filter to collect the foreign matter, the foreign matter in the active material can be intensively collected with a filter of a small area, so that the foreign matter detection rate can be significantly increased. For such wet detection of foreign matter, a foreign matter detection instrument (kit) is required that can maintain and protect the foreign matter collection filter in a sealed state from the outside and can continuously introduce the suspension into the foreign matter collection filter.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0012] The present invention has been devised to solve the above problems, and is for providing a foreign matter collection kit that can maintain and protect a foreign matter collection filter in a sealed state from the outside during wet detection of foreign matter.

[0013] Also, the present invention is for providing a foreign matter collection kit that can continuously introduce a suspension into a foreign matter collection filter.

[0014] Also, the present invention is for providing a foreign matter collection kit that can position a foreign matter collection filter in a kit so as to collect foreign matter on a predetermined minimum foreign matter collection area.

Means for Solving the Problems

[0015] The foreign matter collection kit for an electrode active material according to an embodiment of the present invention has a hollow main body portion provided with a first hollow channel, and both ends of the first hollow channel are respectively opened on the upper surface and the lower surface of the hollow main body portion to form a first inlet and a first outlet. An upper kit portion, a hollow main body portion provided with a second hollow channel, both ends of the second hollow channel are respectively opened on the upper surface and the lower surface of the hollow main body portion to form a second inlet and a second outlet. A lower kit portion, and a foreign matter collection filter fixed between the upper kit portion and the lower kit portion by connecting the upper kit portion and the lower kit portion so that the first hollow channel and the second hollow channel are concentrically arranged, the foreign matter collection filter having a predetermined pore size.

[0016] The first inlet, the first hollow channel, and the first outlet, and the second inlet, the second hollow channel, and the second outlet may be concentrically arranged.

[0017] As an example, the diameters of the first inlet, the first hollow channel, and the first outlet, and the second inlet, the second hollow channel, and the second outlet may be the same.

[0018] As an exemplary embodiment, one of the opposing surfaces of the upper kit portion and the lower kit portion is provided with a fitting protrusion, and the other surface is provided with an insertion groove. The upper kit portion and the lower kit portion may be coupled by coupling the fitting protrusion to the insertion groove.

[0019] As an exemplary embodiment, the opposing surfaces of the upper kit portion and the lower kit portion are provided with screw threads that mesh with each other, and the upper kit portion and the lower kit portion may be screwed together.

[0020] The foreign matter collection area of the foreign matter collection filter may 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 that scans X-rays to analyze foreign matters.

[0021] The foreign matter collection filter is concentrically installed between the first outlet and the second inlet so as to cover the entire first outlet and the second inlet, and the area of the foreign matter collection region of the foreign matter collection filter may be the same as the areas of the first outlet and the second inlet.

[0022] As an example, it further includes a filter mounting sheet that surrounds the foreign matter collection filter and is coupled to the foreign matter collection filter, and the filter mounting sheet may be fixedly installed between the upper kit portion and the lower kit portion.

[0023] The foreign matter collection filter may be a polymer filter.

[0024] At least one of the upper surface of the lower kit portion and the lower surface of the upper kit portion may be provided with a receiving groove for receiving the foreign matter collection filter.

[0025] As another example, one of the upper surface of the lower kit portion and the lower surface of the upper kit portion is provided with a receiving groove for receiving the foreign matter collection filter, and the other of the upper surface of the lower kit portion and the lower surface of the upper kit portion is provided with a protruding cover portion that is inserted into the receiving groove and covers the foreign matter collection filter.

[0026] The upper surface of the upper kit portion may be provided with an injection pipe that communicates with the first hollow channel and extends upward.

[0027] At least one of the first hollow channel and the second hollow channel may be provided with a tapered channel portion whose channel cross-sectional area increases toward the outlet of the hollow channel at the lower part of the hollow channel.

[0028] As an exemplary embodiment, a first lower surface step portion is provided on the outside of the lower surface of the upper kit portion, a first upper surface step portion having a shape that meshes with the first lower surface step portion is provided on the outside of the upper surface of the lower kit portion, and the opposing vertical surfaces of the first lower surface step portion and the first upper surface step portion may be screw-coupled.

[0029] As a specific embodiment, a second lower surface step portion following the first lower surface step portion is provided inside the lower surface of the upper kit portion, and a second upper surface step portion that follows the first upper surface step portion and meshes with the second lower surface step portion is provided inside the upper surface of the lower kit portion, and the foreign matter collection filter may be installed between the opposing horizontal planes of the second upper surface step portion and the second lower surface step portion.

Effects of the Invention

[0030] According to the present invention, the foreign matter collection filter can be maintained and protected inside the kit in a sealed state from the outside during wet detection of foreign matter.

[0031] Also, according to the present invention, a suspension can be continuously introduced into the foreign matter collection filter, and a large-capacity electrode active material can be rapidly analyzed and inspected.

[0032] Also, according to the present invention, the foreign matter collection filter can be positioned inside the kit so as to be able to collect foreign matter in a predetermined minimum foreign matter collection region area. Thereby, considering the resolution and scan speed of the analyzer, the electrode active material can be analyzed within a short time, and foreign matter can be detected rapidly.

[0033] By applying the foreign matter collection kit of the present invention to a wet detection method, foreign matter contained in the electrode active material can be detected with a high probability.

Brief Description of the Drawings

[0034]

Figure 1

Figure 2

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Figure 8

Embodiments for Carrying Out the Invention

[0035] Hereinafter, the present invention will be described in detail. Before that, terms and words used in this specification and the claims should not be construed as being limited to their ordinary or dictionary meanings. 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.

[0036] 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.

[0037] Terms such as "upper" or "lower", "front" or "rear", or "arrangement" or "array" in the present invention are not construed in a restrictive sense and can be interpreted as examples of words indicating position and orientation.

[0038] Hereinafter, the present invention will be described in detail.

[0039] FIG. 1 is a schematic diagram showing a foreign object detection device for an electrode active material that wet-detects foreign objects using the foreign object collection kit of the present invention, and FIGS. 2 and 3 are a schematic diagram and a cross-sectional view of the foreign object collection kit according to the first embodiment of the present invention.

[0040] The foreign object detection device may include a suspension tank 10 containing a suspension L in which an electrode active material is uniformly dispersed, a filter 150 having a predetermined pore size and filtering the suspension L transferred from the suspension tank 10 to collect foreign objects in the electrode active material, and an analyzer 30 that analyzes the filter on which foreign objects are collected to detect at least one of the type of foreign object, the number of foreign objects, the shape of the foreign object, and the size of the foreign object.

[0041] 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.

[0042] 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), Li x 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 may be any one selected from the group consisting of FePO4 (0.5 < x < 1.3) or a mixture of two or more thereof. Further, the lithium-containing transition metal oxide can also be coated with a metal or metal oxide such as aluminum (Al). In addition to the lithium-containing transition metal oxide, one or more of sulfide, selenide, and halide can be used.

[0043] 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.

[0044] Foreign substances are inevitably mixed into the above 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 that of the electrode active material. Therefore, the foreign substances in the active material can be collected by a filter 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 above filter and be separated from the foreign substances. Also, the metal foreign substances can be adsorbed and collected by a magnetic member.

[0045] As described above, conventionally, the electrode active material was in powder form, and the powder was filtered to detect foreign substances by a dry method for detecting metal foreign powder. However, in the conventional method, the loss rate of foreign substances was large and the foreign substance detection rate was very low. Alternatively, it was difficult to quickly inspect a large-capacity electrode active material to detect foreign substances in accordance with the mass production speed of secondary batteries.

[0046] The above foreign substance detection device detects foreign substances by a so-called wet detection method in which the electrode active material is suspended in a predetermined liquid to form a suspension L, and the suspension L is continuously passed through a filter to collect the foreign substances.

[0047] The suspension tank 10 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 the liquid without being dissolved, like muddy water. That is, the active material and the foreign substances contained therein in the suspension L of the electrode active material are spread in the liquid in a state of not being dissolved in the liquid. Therefore, when the suspension L is passed through a predetermined foreign substance collection filter, the foreign substances can be collected on the filter.

[0048] Referring to FIG. 1, a suspension tank 10 is shown which is provided with a stirring member 11 for uniformly dispersing an electrode active material and foreign matter by stirring.

[0049] The suspension tank 10 is a kind of container capable of uniformly dispersing the electrode active material by suspending the electrode active material in a predetermined liquid and stirring it. In FIG. 1, the stirring member 11 includes a rotating shaft rotated by a predetermined driving source (not shown) such as a motor, and a stirring blade 11a 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 capable of suitably stirring the liquid can also be adopted.

[0050] The liquid in which the electrode active material is suspended may be a liquid having the property that the active material and foreign matter can float in the liquid on the suspension without dissolving the active material and foreign matter. 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 pressure treatment device to remove salts and filtering. DI water is water from which ions have been removed by an 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.

[0051] A suspension L in which the active material and foreign matter are uniformly dispersed by stirring can be obtained. Therefore, when a suspension in which the sample is uniformly dispersed is passed through a filter, a large amount of the sample can be filtered without clogging the filter. In particular, by continuously transferring the suspension to the filter at a constant flow rate, a large amount of foreign matter can be accumulated and collected on a filter with a limited area. According to an exemplary embodiment, according to the foreign matter detection device, analysis of a large-capacity electrode active material of 50 to 100 g is possible. However, the amount of the active material is not limited thereto. Compared with the conventional method in which only sampling at the 10 mg level was possible, according to the foreign matter detection device, hundreds to thousands of times or more of the active material can be analyzed. Also, a large-capacity active material can be quickly inspected and analyzed.

[0052] Filter 150 filters the suspension transferred from suspension tank 10, allows the active material particles with small sizes to pass through, and collects only the foreign matters with large sizes. For this purpose, the filter 150 may have a pore size corresponding to the size of the foreign matters to be collected.

[0053] The pore size may be in the range of 30 to 90 μm. More specifically, the pore size may be 30 to 90 μm, 30 to 80 μm, 30 to 50 μm, 50 to 90 μm, 60 to 90 μm, 40 to 80 μm, 40 to 60 μm, 45 to 65 μm, or 50 to 70 μm.

[0054] When the pore size is less than the lower limit, a part of the electrode active material (for example, the positive electrode active material) that must be drained through the filter may also be collected by the filter. In this case, the positive electrode active material collected by the filter during the X-ray scan by the XRF analyzer can hide the foreign matters to be detected, and the foreign matter detection rate may decrease.

[0055] When the pore size exceeds the upper limit, the foreign matters to be detected are drained without being collected by the filter, and the foreign matter detection rate may decrease.

[0056] Filter 150 may adopt those suitable for filtering, such as non-woven fabric, polymer, and stainless steel. However, since a metal filter can provide a magnetic repulsive force to metal foreign matters 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.

[0057] To prevent contamination of the suspension, the suspension in suspension tank 10 can be transferred to the filter in a sealed state from the outside. Also, in order to prevent contamination from the outside during the filtering process, the filter needs to be installed in an environment sealed from the outside.

[0058] For this purpose, the foreign object detection device may include a sealed conduit 20 and the foreign object collection kit 100 of the present invention.

[0059] Referring to FIG. 1, the sealed conduit 20 is connected between the suspension tank 10 and the foreign object collection kit 100. At the connection part of the sealed conduit 20 and the suspension tank 10 and at the connection part of the sealed conduit and the foreign object collection kit 100, a predetermined sealing member (for example, an O-ring) may be installed for airtightness. The sealed conduit 20 can prevent leakage of the suspension and transfer a fixed amount of the suspension to the foreign object collection kit. Also, the sealed conduit 20 can prevent the inflow of external air and prevent the mixing of unnecessary bubbles that interfere with foreign object collection. A predetermined pump may be employed to transfer a fixed flow rate of the suspension from the suspension tank 10 to the filter.

[0060] The sealed conduit 20 may be manufactured from a flexible material. For example, a tube or hose (hose) made of a flexible plastic resin (for example, urethane resin) or silicone resin can be used as the sealed conduit. By bending the flexible hose, the transfer path of the suspension can be freely set between the suspension tank 10 and the filter 150.

[0061] The foreign object collection kit 100 of the present invention is a type of filter fixture that protects the filter from external influences and also fixes the filter in a certain position to collect foreign objects on a specific filter area.

[0062] Hereinafter, the foreign object collection kit of the present invention will be described in detail.

[0063] (First Embodiment) The foreign object collection kit 100 according to the present invention includes a liquid inlet, a liquid outlet, and a flow channel connecting the liquid inlet and the liquid outlet. The foreign object collection kit 100 is configured to be sealed from the outside except for the liquid inlet and the liquid outlet. Therefore, the filter 150 can be protected from the external environment inside the foreign object collection kit 100 and stably collect foreign objects. The filter is installed in the flow channel.

[0064] In addition, the liquid inlet of the foreign matter collection kit 100 and the suspension tank 10 are connected by a sealed conduit 20. A sealing member such as an O-ring can be installed at the connection between the liquid inlet and the sealed conduit as described above.

[0065] Referring to FIGS. 2 and 3, the foreign matter collection kit 100 of the first embodiment has a hollow main body portion provided with a first hollow channel 113. Both ends of the first hollow channel 113 are opened to the upper surface 111 and the lower surface 112 of the hollow main body portion respectively, forming an upper kit portion 110 with a first inlet I1 and a first outlet O1, and a hollow main body portion provided with a second hollow channel 123. Both ends of the second hollow channel 123 are opened to the upper surface 121 and the lower surface 122 of the hollow main body portion respectively, and includes a lower kit portion 120 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 100, and the second outlet O2 serves as the liquid discharge port. Also, the first hollow channel and the second hollow channel serve as the flow channels of the foreign matter collection kit 100.

[0066] By connecting the upper kit portion 110 and the lower kit portion 120 such that the first hollow channel 113 and the second hollow channel 123 are concentrically arranged, the foreign matter collection filter 150 can be fixed between the upper kit portion 110 and the lower kit portion 120.

[0067] The first inlet I1, the first hollow channel 113, and the first outlet O1, and the second inlet I2, the second hollow channel 123, and the second outlet O2 are concentrically arranged. The sealed conduit 20 is connected to the first inlet I1 which is a liquid inlet. Therefore, the suspension introduced into the sealed conduit 20 is transferred to the foreign matter collection filter 150 through the first inlet I1 - the first hollow channel 113 - the first outlet O1. The liquid filtered by the filter (mainly containing the electrode active material) is discharged downward through the second inlet I2 - the second hollow channel 123 - the second outlet O2. In this way, since the foreign matter collection kit 100 allows the suspension to pass from the upper part to the lower part, it has a structure that can smoothly filter the suspension by gravity. The diameters and lengths of the first hollow channel 113 and the second hollow channel 123 can be suitably determined in consideration of the flow rate and flow velocity of the suspension. For example, the total length of the entire flow channel combining the first hollow channel and the second hollow channel can be determined in the range of 45 to 70 mm, but it is not limited thereto. Accordingly, the height of the entire foreign matter collection kit 100 combining the upper kit part 110 and the lower kit part 120 can also be determined in the range of 45 to 70 mm, but it is not limited thereto.

[0068] The diameters φ3 of the first inlet I1, the first hollow channel 113, and the first outlet O1, and the second inlet I2, the second hollow channel 123, and the second outlet O2 can be the same. However, as will be described later, the diameters of the first hollow channel and the second hollow channel can also vary along the height direction.

[0069] Figure 2 shows the diameter φ1 of the foreign matter collection kit 100, the diameter φ2 of the filter and the filter mounting groove provided in the foreign matter collection kit 100, the first hollow channel, the second hollow channel, and the diameter φ3 of the foreign matter collection area, respectively.

[0070] As an exemplary embodiment, the upper kit portion 110 and the lower kit portion 120 can be joined by fitting or screwing. For example, a fitting protrusion 112a is provided on one of the opposing surfaces of the upper kit portion 110 and the lower kit portion 120, and an insertion groove 121a is provided on one of the other surfaces. By joining the fitting protrusion 112a to the insertion groove 121a, the upper kit portion 110 and the lower kit portion 120 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 portion 110 and the lower kit portion 120, and the upper kit portion 110 and the lower kit portion 120 can be screwed together (see the second embodiment described later). Here, the opposing surfaces of the upper kit portion 110 and the lower kit portion 120 can be horizontal surfaces. Alternatively, as shown in the second embodiment, when a step is formed on the opposing surfaces of the upper kit portion 110 and the lower kit portion 120, the opposing surfaces can be vertical surfaces that form a part of the stepped surface. Therefore, by arranging screw threads having a meshing shape with each other on the opposing vertical surfaces of the upper kit portion 110 and the lower kit portion 120, the upper kit portion 110 and the lower kit portion 120 can be screwed together. Since the upper kit portion 110 and the lower kit portion 120 are joined and the filter 150 is exposed only within the suspension permeation region (the first hollow channel and the second hollow channel), foreign matter is collected only in such a permeation region. Also, since the upper kit portion 110 and the lower kit portion 120 are firmly joined by screws or the like, foreign matter does not diffuse outside the permeation region of the filter.

[0071] The filter 150 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 matter collection region 151 of the filter is the same as the areas of the first outlet O1 and the second inlet I2.

[0072] At least one of the upper surface 121 of the lower kit part 120 and the lower surface 112 of the upper kit part 110 may be provided with a receiving groove for receiving the filter. For example, a filter receiving groove 121b may be disposed only on the upper surface 121 of the lower kit part 120, and the lower surface 112 of the upper kit part 110 facing it may be a flat surface simply covering the filter. Conversely, a filter receiving groove 112b may be disposed only on the lower surface 112 of the upper kit part 110, and the upper surface 121 of the lower kit part 120 facing it may be a flat surface simply covering the filter. Alternatively, as shown in FIG. 3, grooves 112b and 121b for receiving the filter may be provided on both the lower surface 112 of the upper kit part 110 and the upper surface 121 of the lower kit part 120. With such a receiving groove, the filter can be stably seated between the upper kit part 110 and the lower kit part 120, and the filter can be fixed without flowing in the receiving groove when the upper kit part 110 and the lower kit part 120 are joined.

[0073] The foreign matter collection kit 100 may be made of a material excellent in chemical resistance, abrasion resistance, and strength. For example, the foreign matter collection kit 100 may be manufactured using PEEK (Poly Ether Ether Keton) which is excellent in chemical resistance and strength.

[0074] FIG. 4 is a schematic diagram showing the area of the foreign matter collection region of the foreign matter collection filter according to the present invention, and FIG. 5 is a schematic diagram showing a state in which the foreign matter collection filter is attached to an inspection film.

[0075] Conventionally, since a dry method of filtering active material powder containing foreign matter by air pressure was selected, the foreign matter could not spread over a wide area by air pressure to increase the collection density of the foreign matter. Therefore, a complicated operation of attaching a 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 foreign matter collection and detection efficiency was very low. Alternatively, since the foreign matter was detected together with the active material, it was difficult to detect the foreign matter with a narrow X-ray scan area.

[0076] On the one hand, the foreign matter detection device can minimize the area of the foreign matter collection region of the filter by uniformly dispersing foreign matter in a suspension tank to form a suspension and continuously introducing the suspension into the filter. That is, by uniformly dispersing foreign matter, the foreign matter is prevented from being concentrated and distributed in the suspension, and the filter is prevented from clogging during filtering. In addition, the suspension in which foreign matter is uniformly dispersed is continuously introduced into a filter having a pore size capable of filtering foreign matter, and only foreign matter can be intensively collected on the filter. By collecting foreign matter by such a wet method or wet pretreatment method, foreign matter can be intensively collected in a small area.

[0077] Referring to Fig. 4(a), the small central circle with respect to the large outer circle is the boundary line of the region 151 where the filter is collected. 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 of the central circle φ3 is the same as the diameters of the first outlet O1 of the upper kit part 110 and the second inlet I2 of the lower kit part 120. As an exemplary embodiment, the diameter of the central circle φ3 can be about 1 to 2 cm. However, the diameter and area of the foreign matter collection region 151 are not limited thereto, and can be made larger or smaller according to the resolution and scan speed of the analyzer. 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. In addition, 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 instead of the entire filter. The region of the filter that is not filtered becomes the part fixed between the upper kit part 110 and the lower kit part 120.

[0078] According to the present invention, since the area of the foreign matter collection region 151 can be minimized, the filter can also be made small to match that area. For example, as shown in Fig. 4(b), an exemplary embodiment may include a filter mounting sheet 160 that is joined surrounding the small-area filter.

[0079] That is, the filter mounting sheet 160 surrounds the foreign matter collection filter 150 and is coupled to the foreign matter collection filter. The filter mounting sheet 160 can be fixedly installed between the upper kit part 110 and the lower kit part 120. The filter mounting sheet 160 is a support sheet to which the foreign matter collection filter is coupled and mounted. Also, when the filter mounting sheet 160 is fixedly installed between the upper kit part 110 and the lower kit part 120, the foreign matter collection filter 150 can be accurately positioned at the filtering position through which the suspension passes. In this case, the diameter of the filter is the same as or slightly larger than the diameters of the first outlet O1 of the upper kit part 110 and the second inlet I2 of the lower kit part 120, which is sufficient.

[0080] Figure 5 is a schematic diagram showing a state in which the filter is attached to the inspection film. In order to inspect with a foreign matter analyzer, the filter 150 can be attached to the inspection film F, and the inspection film F can be put into the analyzer for analysis. As shown in the figure, instead of scanning the entire area of the filter, only the small circular portion in the center of the filter needs to be scanned, so the inspection speed and efficiency are greatly improved.

[0081] As described above, the area of the foreign matter collection region 151 of the foreign matter collection filter can be set to an area where the X-ray scan can be completed within a predetermined time under the set resolution and set scan speed conditions of the foreign matter analyzer that scans the X-ray to analyze foreign matters.

[0082] (Second Embodiment) Figures 6 and 7 are a schematic diagram and a cross-sectional view of a foreign matter collection kit 200 according to the second embodiment of the present invention.

[0083] In the second embodiment, an injection tube 214 that communicates with the first hollow channel 213 and extends upward is provided on the upper surface 211 of the upper kit portion 210 of the foreign matter collection kit 200. Since the injection tube 214 protrudes upward, it is easy to couple with the above-described sealed conduit 20. For example, the injection tube 214 can be firmly fitted into a urethane hose, and the sealed conduit 20 can be connected to the foreign matter collection kit 200 while maintaining the airtightness. Further, since the injection tube 214 of a predetermined length protrudes and is inserted into the sealed conduit 20 by a certain length, the risk of leakage of the suspension can be prevented. Further, since the injection tube 214 extending upward serves as a funnel, the operation of injecting the suspension into the foreign matter collection kit 200 at the inlet I1' of the injection tube 214 is also very simple.

[0084] In the examples of FIGS. 2 and 3, the diameters of the first hollow channel 113 and the second hollow channel 123 were the same. However, in order to make the flow of the suspension smooth and the discharge of the liquid passing through the filter smooth, the diameter of the hollow channel can be changed along the height. For example, in the present embodiment, a tapered channel portion 213b, 223b in which the channel cross-sectional area increases toward the outlet of each hollow channel may be provided at the lower part of at least one of the first hollow channel 213 and the second hollow channel 223.

[0085] As shown in FIGS. 6 and 7, the first hollow channel 213 can be composed of an upper channel 213a with a constant diameter and a lower channel 213b with a variable diameter. The upper channel 213a is connected to the injection tube 214 described above. The diameter of the upper channel 213a is set to be the same as the inner diameter of the injection tube 214 for a stable downward flow of the suspension. On the other hand, the lower channel 213b following the upper channel 213a has a tapered shape in which the cross-sectional area gradually increases toward the first outlet O1. That is, the lower channel becomes a tapered channel portion 213b. Thereby, the suspension flowing downward can be introduced onto the filter more smoothly and with a larger flow rate. In one aspect, the second inlet I2, the second hollow channel 223, and the second outlet O2 of the lower kit portion 220 can have the same diameter as shown in FIG. 3. However, in this case, the diameter of the second inlet I2 and the like can be set to be the same as the diameter of the first outlet O1 of the tapered channel portion of the upper kit portion 210 that has been expanded.

[0086] Alternatively, as shown in FIGS. 6 and 7, the second hollow channel 223 can be composed of an upper channel 223a with a constant diameter and a lower channel 223b with a variable diameter. The upper channel 223a is connected to the first outlet O1 of the first hollow channel 113. The diameter of the upper channel 223a is set to a constant diameter for a stable downward flow of the suspension. On the other hand, the lower channel 223b following the upper channel 223a has a tapered shape in which the cross-sectional area gradually increases toward the second outlet O2. That is, the lower channel becomes a tapered channel portion 223b. Thereby, the suspension containing the filtered active material can be discharged more smoothly and with a larger flow rate.

[0087] FIG. 7 illustrates the case where both the first hollow channel 213 and the second hollow channel 223 have tapered channel portions, but it is also possible to provide a tapered channel portion only in either the first hollow channel or the second hollow channel.

[0088] The foreign object collection kit 200 of FIGS. 6 and 7 is provided with a plurality of stepped portions S11, S12, S21, and S22 on the opposing surfaces of the upper kit portion 210 and the lower kit portion 220. By the connection between the stepped portions S11, S12, S21, and S22, the upper kit portion 210 and the lower kit portion 220 are more firmly connected, and the filter 250 can be more firmly fixed between the upper kit portion 210 and the lower kit portion 220. The upper kit portion 210 is provided with two stepped portions on the lower surface 212, and the horizontal plane facing the lower kit portion 220 is divided into three (212a, 212b, 212c). Also, the lower kit portion 220 is provided with two stepped portions on the upper surface 221, and the horizontal plane facing the upper kit portion 210 is divided into three (221a, 221b, 221c). A vertical plane is arranged between the adjacent horizontal planes among the three horizontal planes.

[0089] Referring to the drawings, a first lower surface stepped portion S11 is provided outside the lower surface 212 of the upper kit portion. Also, outside the upper surface 221 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 and one vertical plane interposed therebetween. At this time, the opposing vertical planes of the first lower surface stepped portion S11 and the first upper surface stepped portion S21 can be screw-coupled with screw threads A1, A2 that mesh with each other. The vertical length of the screw portion arranged on the vertical plane is determined by the descending distance of the upper kit portion 210 due to the screw connection. As will be described later, the upper kit portion 210 and the lower kit portion 220 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 250 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 210 at the time of screw connection and the descending distance of the second lower surface stepped portion S12, and is set so as to avoid excessive pressing of the filter.

[0090] Inside the lower surface 212 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 221 of the lower kit part, a second upper surface step part S22 following the first upper surface step part S21 and having a shape meshing with the second lower surface step part S12 is provided. The filter 250 is installed between the opposing horizontal planes 212c and 221c of the second upper surface step part S22 and the second lower surface step part S12. The side surface of the filter 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 210 and the lower kit part 220 are screwed together, the filter 250 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 is stably maintained and can continuously filter foreign substances.

[0091] The second upper surface step part S22 forms a receiving groove in which the foreign substance collection filter 250 is received. In this case, the second lower surface step part S12 inserted into the second upper surface step part S22 is inserted into the receiving groove and serves as a protruding cover that covers the filter. When the upper kit part 210 and the lower kit part 220 are joined, the foreign substance collection filter 250 can be stably fixed and maintained by the interval between the receiving groove and the protruding cover.

[0092] As described above, when the foreign substance collection filters 150 and 250 are installed in the foreign substance collection kits 100 and 200 of the present invention, filtering can be performed in an environment protected from the outside. For example, a filter is positioned between the upper kit parts 110 and 210 and the lower kit parts 120 and 220, and the upper kit parts 110 and 210 and the lower kit parts 120 and 220 are joined to fix the filter between the upper and lower kit parts. The remaining part of the filter outside the foreign substance collection area (or the filter mounting sheet 160 in FIG. 4) is mounted in the mounting groove, and when the upper and lower kit parts are joined, it is possible to prevent foreign substances from diffusing outside the foreign substance collection area. That is, the foreign substance collection area can be restricted only to the area through which the suspension permeates.

[0093] Referring back to FIG. 1, the foreign object detection device includes an analyzer that analyzes the foreign object collection filter to detect at least one of the type of foreign object, the number of foreign objects, the shape of the foreign object, and the size of the foreign object. According to the foreign object collection kits 100 and 200 of the present invention, target foreign objects can be accumulated and collected in a small area. Therefore, it can be expected that the foreign object detection efficiency will be significantly improved regardless of the analyzer used.

[0094] As one of the above analyzers, an XRF analyzer can be used. XRF (X-Ray Fluorescence) analysis is a method of analyzing a sample by irradiating (scanning) the sample to be inspected with X-rays and analyzing the secondary fluorescent X-rays generated inside the sample. By using an XRF analyzer, the filter on which foreign objects are collected can be irradiated with X-rays, and the foreign objects can be qualitatively and quantitatively analyzed from the secondary fluorescent X-rays generated for each type of foreign object. Fluorescent X-rays have different wavelengths and energies for each element. Therefore, qualitative analysis of grasping the type of foreign object by the wavelength or energy of the secondary fluorescent X-ray is possible.

[0095] Also, the elements of the foreign object can be identified or the number of foreign objects can be grasped by mapping analysis obtained from the two-dimensional image acquired by X-ray scanning. For example, if the foreign object collection area is irradiated with X-rays and scanned, a mapping map having shadows in pixel units can be obtained. The number of foreign objects can also be grasped by a predetermined software having an algorithm for converting the shadows of the mapping map into numbers. Therefore, quantitative analysis of foreign objects in the electrode active material is also possible.

[0096] On the other hand, the shape and size of the foreign object can be grasped by, for example, an optical microscope such as an SEM or a TEM or an electron microscope. In recent years, an analyzer in which a microscope device such as an SEM is integrated with an XRF analyzer has also been put on the market. Therefore, all of the type of foreign object, the number of foreign objects, the shape of the foreign object, and the size of the foreign object can be grasped by such one analyzer. What is important is not which analyzer is used, but rather whether any analyzer can be used to increase the integration degree of foreign object collection, minimize the area of the foreign object collection area, and improve the foreign object detection efficiency. The present invention achieves such a problem.

[0097] The foreign matter collection kits 100 and 200 of the present invention can set the area of the foreign matter collection region of the filter 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. That is, as shown in FIG. 4, the area of the foreign matter collection region can be a small area. When scanning such a small area with an XRF analyzer 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-mentioned suspension and filtering times, it does not take one hour for one analysis, so the electrode active material of a specific lot can be quickly inspected in the mass production process and can meet the requirements of mass production.

[0098] On the other hand, the shape of the foreign matter collection region is not limited to a circular shape as shown in FIG. 4. That is, by changing the shapes of the first inlet I1, the first hollow channel 113, and the first outlet O1 to a rectangular shape, an elliptical shape, or other shapes, the shape of the foreign matter collection region can be changed to any rectangular shape, elliptical shape, or other shapes.

[0099] The shapes of the second inlet I2, the second hollow channel 123, and the second outlet O2 can also be changed to a rectangular shape, an elliptical shape, or other shapes.

[0100] <Example>

[0101] 0.0034 g of foreign matter (Cu) was added to 100 g of NCM-based positive electrode active material powder and suspended in 1 L of DI water, and stirred in the suspension tank 10 as shown in FIG. 1 for 8 minutes to produce a positive electrode active material suspension. Pressure was applied to the suspension with a peristaltic pump and transferred to a PEEK-made foreign matter collection kit 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 matter collection kit. As the first hollow channel 113, a square tube of 15 mm × 15 mm was adopted, whereby the area of the foreign matter collection region 151 was minimized to 15 mm × 15 mm.

[0102] The foreign matter collection kit was disassembled, the filter was attached to the inspection film, and analyzed in an XRF analyzer (EA8000, manufactured by Hitachi, Ltd.).

[0103] The XRF analyzer irradiated X-rays on a scanning size of 15 mm × 15 mm in a mapping scanning method. The resolution was 30 μm / pixel, and the scanning speed was 5 ms.

[0104] Figure 8 is a graph showing the correlation between the amount of foreign matter powder and the number of foreign matters.

[0105] Figure 8 shows the correlation between the weight and the number of Cu. The 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, specific explanations about it are omitted.

[0106] Figure 8 shows the correlation coefficient between the number and 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 pieces of Cu powder exist in 0.003 g of Cu.

[0107] [Table 1]

[0108] 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. The average foreign matter size is 57 to 85 μm.

[0109] The number of Cu foreign matters collected by the filter and measured by the XRF analyzer varies depending on the pore size of the filter. To compare on the same basis, the number of each measured Cu is converted based on a Cu weight of 0.003 g.

[0110] Since there are 2338 powders in Cu 0.003 g in Figure 8, the foreign matter detection rates of Comparative Example 1, Examples 1 to 3, and Comparative Example 2, that is, the recovery rates of the foreign matters recovered from the introduced foreign matters, are 43%, 88%, 81%, 60%, and 19% respectively.

[0111] From the above, if a filter with a pore size suitable for the average size of the foreign matters is selected, the foreign matters can be detected with a high probability of 60% or more, preferably 80% or more.

[0112] From the above, when detecting foreign matters using the foreign matter collection kit of the present invention, the foreign matters contained in the electrode active material can be quickly detected with a high probability, so the detection reliability is greatly improved.

[0113] The above description merely exemplarily explains 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.

[0114] Therefore, the drawings disclosed in the present invention are for explanation purposes 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 by 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

[0115] 100: Foreign matter collection kit L: Suspension 110: Upper kit part 111: Upper surface 112: Lower surface 113: First hollow channel 120: Lower kit part 121: Upper surface 122: Lower surface 123: Second hollow channel 150: Filter 151: Foreign matter collection area 160: Filter mounting sheet F: Inspection film 200: Foreign matter collection kit 210: Upper kit part 211: Upper surface 212: Lower surface 213: First hollow channel 220: Lower kit part 221: Upper surface 222: Lower surface 223: Second hollow channel 250: Filter

Claims

1. It has a hollow main body portion with a first hollow channel, and both ends of the first hollow channel are respectively opened on the upper surface and the lower surface of the hollow main body portion to form an upper kit portion with a first inlet and a first outlet, and It has a hollow main body portion with a second hollow channel, and both ends of the second hollow channel are respectively opened on the upper surface and the lower surface of the hollow main body portion to form a lower kit portion with a second inlet and a second outlet, and A foreign matter collection filter fixed between the upper kit portion and the lower kit portion by combining the upper kit portion and the lower kit portion so that the first hollow channel and the second hollow channel are concentrically arranged, the foreign matter collection filter having a predetermined pore size.

2. The foreign matter collection kit according to claim 1, wherein the first inlet, the first hollow channel, and the first outlet, and the second inlet, the second hollow channel, and the second outlet are concentrically arranged.

3. The foreign matter collection kit according to claim 2, wherein the diameters of the first inlet, the first hollow channel, and the first outlet, and the second inlet, the second hollow channel, and the second outlet are the same.

4. One of the opposing surfaces of the upper kit portion and the lower kit portion is provided with a fitting protrusion, and the other surface is provided with an insertion groove, and the upper kit portion and the lower kit portion are combined by coupling the fitting protrusion to the insertion groove. The foreign matter collection kit according to claim 1.

5. The opposing surfaces of the upper kit portion and the lower kit portion are provided with screw threads that mesh with each other, and the upper kit portion and the lower kit portion are screwed together. The foreign matter collection kit according to claim 1.

6. The foreign matter collection area of the foreign matter collection filter is set to an area where X-ray scanning is completed within a predetermined time under the set resolution and set scan speed conditions of a foreign matter analyzer that scans X-rays to analyze foreign matters. The foreign matter collection kit according to claim 1.

7. The foreign matter collection filter is concentrically installed between the first outlet and the second inlet so as to cover the entire first outlet and the second inlet, The area of the foreign matter collection area of the foreign matter collection filter is the same as the areas of the first outlet and the second inlet. The foreign matter collection kit according to claim 6.

8. It further includes a filter mounting sheet that surrounds the foreign matter collection filter and is coupled to the foreign matter collection filter. The foreign matter collection kit according to claim 6, wherein the filter mounting sheet is fixedly installed between the upper kit part and the lower kit part.

9. The foreign matter collection kit according to claim 1, wherein the foreign matter collection filter is a polymer filter.

10. The foreign matter collection kit according to claim 1, wherein at least one of the upper surface of the lower kit part and the lower surface of the upper kit part is provided with a receiving groove for receiving the foreign matter collection filter.

11. One of the upper surface of the lower kit part and the lower surface of the upper kit part is provided with a receiving groove for receiving the foreign matter collection filter, The foreign matter collection kit according to claim 1, wherein the other one of the upper surface of the lower kit part and the lower surface of the upper kit part is provided with a protruding cover part that is inserted into the receiving groove and covers the foreign matter collection filter.

12. The foreign matter collection kit according to claim 1, wherein an injection pipe that communicates with the first hollow channel and extends upward is provided on the upper surface of the upper kit part.

13. The foreign matter collection kit according to any one of claims 1 to 12, wherein at least one of the first hollow channel and the second hollow channel is provided with a tapered channel part whose channel cross-sectional area increases toward the outlet of the hollow channel at the lower part.

14. A first lower surface step part is provided on the outside of the lower surface of the upper kit part, A first upper surface step part having a shape that meshes with the first lower surface step part is provided on the outside of the upper surface of the lower kit part, The foreign matter collection kit according to claim 1, wherein the opposing vertical surfaces of the first lower surface step part and the first upper surface step part are screwed together.

15. A second lower surface step part following the first lower surface step part is provided inside the lower surface of the upper kit part, A second upper surface step part that follows the first upper surface step part and meshes with the second lower surface step part is provided inside the upper surface of the lower kit part, The foreign matter collection kit according to claim 14, wherein the foreign matter collection filter is installed between the opposing horizontal surfaces of the second upper surface step part and the second lower surface step part.

Images