Lithium metal cutting system for negative electrodes

Abstract

The present disclosure relates to a lithium metal cutting system for a negative electrode, which includes a lithium metal supply unit that supplies lithium metal, a lithium metal transfer unit that transfers the lithium metal supplied from the lithium metal supply unit, and a lithium metal cutting unit that cuts the lithium metal transferred by the lithium metal transfer unit, wherein the lithium metal transfer unit includes a plurality of rollers and a refrigerant pipe disposed inside each of the plurality of rollers.

Description

[Technical Field]

[0001] This application claims priority rights under Korean Patent Application No. 10-2022-0132889 dated October 17, 2022, and Korean Patent Application No. 10-2023-0137115 dated October 13, 2023, and all content disclosed in the documents of said Korean patent applications is incorporated herein by reference.

[0002] This disclosure relates to a lithium metal cutting system for a negative electrode, and more specifically, to a cutting system for transporting and cutting lithium metal used in a negative electrode, and for cooling the lithium metal during transport and cutting. [Background technology]

[0003] Lithium metal is used as the negative electrode in lithium-ion batteries, and the manufacturing process of lithium-ion batteries requires cutting the lithium metal to match the cell size.

[0004] However, lithium metal has low tensile strength at room temperature and tends to adhere to substrates such as molds and knives. Therefore, when cutting lithium metal, it is necessary to frequently remove the lithium metal that adheres to these substrates, which leads to a problem of reduced cutting speed.

[0005] Furthermore, because the lithium metal adhering to the substrate is difficult to remove, there is a possibility that the cost of manufacturing secondary batteries will increase due to the lithium metal wasted during the lithium metal cutting process.

[0006] Korean Published Patent No. 10-2021-0007673 (hereinafter referred to as Patent Document 1) discloses a method for cutting lithium metal by installing a temperature control member in a cutting device, thereby preventing lithium from easily adhering to the cutting device, improving the efficiency of the lithium cutting process, and enabling easy cutting of lithium into a desired shape.

[0007] However, since Patent Document 1 only places a temperature control member in the cutting device, the problem of lithium metal adhering to rollers and other parts during the lithium metal transfer process still occurs.

[0008] Furthermore, according to Patent Document 1, the lithium metal must be cooled by the cutting device, but it is difficult to cool the lithium metal placed on the cutting device in a short time. Therefore, the lithium metal will not be sufficiently cooled unless it is left on the cutting device for a certain period of time or longer. This increases the time required for the lithium metal cutting process, which may lead to a problem where the cutting speed of the lithium metal decreases. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Korean Published Patent No. 2021-0007673 (2021.01.20) [Overview of the project] [Problems that the invention aims to solve]

[0010] The object of the present invention is to provide a lithium electrode manufacturing apparatus and lithium electrode manufacturing method that solves the above-mentioned problems, and in which the lithium metal does not adhere to rollers or the like during the transfer process of lithium metal, and the lithium metal is sufficiently cooled when it reaches the cutting device, so that the lithium metal is cooled to a desired temperature in a short time in the cutting device, thereby effectively cutting lithium metal. [Means for solving the problem]

[0011] To achieve the above object of the present invention, a lithium metal cutting system according to an embodiment of the present invention includes a lithium metal supply unit that supplies lithium metal, a lithium metal transfer unit that transfers the lithium metal supplied from the lithium metal supply unit, and a lithium metal cutting unit that cuts the lithium metal transferred by the lithium metal transfer unit. The lithium metal transfer unit can include a plurality of rollers and refrigerant pipes disposed inside each of the plurality of rollers.

[0012] In one embodiment, refrigerant is supplied to the refrigerant pipes of each of the plurality of rollers, and the temperature of the refrigerant may decrease as it goes from the lithium metal supply unit toward the lithium metal cutting unit.

[0013] In one embodiment, the temperature of the refrigerant may gradually decrease.

[0014] In one embodiment, the lithium metal cutting unit includes a cutting stage, and a cutting refrigerant pipe can be disposed inside the lithium metal cutting stage.

[0015] In one embodiment, the refrigerant is also supplied to the inside of the cutting refrigerant pipe, and the temperature of the refrigerant supplied to the inside of the cutting refrigerant pipe may be lower than or the same as the temperature of the refrigerant supplied to the adjacent refrigerant pipe.

[0016] In one embodiment, at least some of the plurality of rollers can be arranged at different heights from each other.

[0017] In one embodiment, the lithium metal supply unit includes a winding roller that winds up the lithium metal, and refrigerant can be supplied to the inside of the winding roller.

[0018] In one embodiment, refrigerant is supplied to the refrigerant pipes of each of the plurality of rollers, and the temperatures of the refrigerants can be the same as each other.

[0019] In one embodiment, the refrigerant is also supplied inside the cut refrigerant pipe. The temperature of the refrigerant supplied to the inside of the cut refrigerant pipe may be lower than or the same as the temperature of the refrigerant supplied to the adjacent refrigerant pipe. [Effects of the Invention]

[0020] The effect of this disclosure is that by cooling the lithium metal during the transfer and cutting of the lithium metal for the negative electrode, the tensile strength of the lithium metal is increased, thereby preventing the lithium metal from adhering to the substrate when the lithium metal is cut. [Brief explanation of the drawing]

[0021] [Figure 1] This figure shows a lithium metal cutting system for a negative electrode according to one embodiment of the present invention. [Figure 2] This figure shows a lithium metal cutting system for a negative electrode according to another embodiment of the present invention. [Figure 3] This figure shows a lithium metal cutting system for a negative electrode according to another embodiment of the present invention. [Figure 4] This is a photograph of a cross-section of lithium metal according to Comparative Example 1 of the present invention. [Figure 5] This is a photograph of a cross-section of lithium metal according to Comparative Example 2 of the present invention. [Figure 6] This is a photograph of a cross-section of lithium metal according to Example 1 of the present invention. [Figure 7] This is a photograph of a cross-section of lithium metal according to Example 2 of the present invention. [Modes for carrying out the invention]

[0022] An embodiment of the present invention will be described in detail below. However, the following description should be understood as illustrative to aid in understanding the present invention, and should not be understood as limiting or restricting the present invention. It should also be understood that the present invention is not limited to the accompanying drawings. A person ordinary in the art will be able to embody the present invention in various forms without departing from the technical spirit of the present invention by referring to the following description and the accompanying drawings.

[0023] negative electrode The negative electrode may contain lithium metal. The negative electrode may also be made of pure lithium metal or a lithium alloy, or it may be used after coating and drying a negative electrode active material on the lithium metal.

[0024] The lithium metal may include at least one of pure lithium, lithium alloys, or lithium metal composite oxides. The lithium alloy may include one selected from the group consisting of Al, Mg, K, Na, Ca, Sr, Ba, Si, Ge, Sb, Pb, In, and Zn. The lithium metal composite oxide may be lithium and one metal (Me) oxide (MeO) selected from the group consisting of Si, Sn, Zn, Mg, Cd, Ce, Ni, and Fe. x ) and, as an example, Li x Fe2O3 (0 < 0 ≤ 1) or Li x WO2(0 <x≦1)であってもよい。

[0025] The lithium metal according to the present invention may have a protective layer, similar to conventional lithium metals with an electrolyte. This protective layer can contain any substance that is lithium-ion conductive, does not interfere with the battery's operation, and does not react with lithium. Examples include a garnet-type ceramic protective film, a protective film composed of lithium-substituted polyacrylic acid, and a molybdenum disulfide substrate protective film. Any protective layer can be used as long as it improves the stability of the lithium metal.

[0026] The lithium metal is generally fabricated with a thickness of 3 μm or more and 500 μm or less. The lithium metal can also form fine irregularities on its surface to strengthen the binding force between the lithium metal and the negative electrode active material or the solid electrolyte, and can be used in various forms such as films, sheets, foils, nets, porous bodies, foaming agents, non-woven fabrics, etc.

[0027] Examples of the negative electrode active material include carbon such as graphitizable carbon and graphite-based carbon:Li x Fe2O3 (0 < 0 ≤ 1), Li x WO2 (0 < x ≤ 1), Sn x Me 1-x Me’ y O z (Me: Mn, Fe, Pb, Ge; Me’: Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, halogen; 0 < x ≤ 1; 1 ≤ y ≤ 3; 1 ≤ z ≤ 8), etc. metal composite oxides; lithium metal; lithium alloy; silicon-based alloy; tin-based alloy; metal oxides such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, and Bi2O5; conductive polymers such as polyacetylene; Li-Co-Ni-based materials, etc. can be used.

[0028] solid electrolyte The solid electrolyte may contain at least one or more of sulfide-based solid electrolytes, oxide-based solid electrolytes, and organic solid electrolytes. For the solid electrolyte according to the present invention, particles with a coated or modified surface can be used. Sulfide-based solid electrolytes have advantages compared to other solid electrolytes in terms of ionic conductivity and production cost. Therefore, the present invention will proceed with the description of examples where sulfide-based solid electrolytes are used.

[0029] The sulfide-based solid electrolyte has a lithium ion conductivity of 10 -2 ~10 -3It has the advantages of a high S / cm ratio, easy formation of a contact interface between the electrode and electrolyte, and good mechanical strength and flexibility. The sulfide-based solid electrolyte powder contains sulfur (S) and has the ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and can include Li-PS glass or Li-PS glass ceramic. The sulfide-based solid electrolyte is not particularly limited in this invention, and all known sulfide-based materials used in the lithium battery field can be used. As an example, sulfide-based solid electrolytes include Li6PS5Cl(LPSCl) and Thio-LISICON(Li 3.25 Ge 0.25 P 0.75 S4), Li2S-P2S5-LiCl, Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-Li2S-P2O5, LiILi3PO4-P2S5, Li2S-P2S5, Li3PS4, Li7P3S 11 , LiI-Li2S-B2S3, Li3PO4-Li2S-Si2S, Li3PO4-Li2S-SiS2, LiPO4-Li2S-SiS, Li 10 GeP2S 12 Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 Li7P3S 11 This can include things like that.

[0030] The thickness of the solid electrolyte can be selected in different ways depending on the desired characteristics of the battery. For example, the thickness after pressing and densifying may preferably be about 0.1 μm to 1000 μm, more preferably about 1 μm to 100 μm, and even more preferably about 10 μm to 50 μm.

[0031] positive electrode The positive electrode can be manufactured, for example, by coating a positive electrode current collector with a positive electrode active material composed of positive electrode active material particles, a conductive material and a binder, and a filler can be further added to the positive electrode mixture as needed.

[0032] The positive electrode current collector is generally manufactured to a thickness of approximately 3 μm to 500 μm and is not particularly limited as long as it does not cause chemical changes in the battery and has high conductivity. For example, one of the following may be used: stainless steel, aluminum, nickel, titanium, and aluminum or stainless steel surface-treated with carbon, nickel-titanium, or silver. In particular, aluminum may be used. The current collector can also have fine irregularities formed on its surface to enhance the adhesion of the positive electrode active material, and can take various forms such as film, sheet, foil, net, porous material, foaming agent, nonwoven fabric, etc.

[0033] The positive electrode active material may, for example, consist of positive electrode active material particles, as well as layered compounds such as lithium nickel oxide (LiNiO2) or compounds substituted with one or more transition metals; chemical formula Li1 +x Mn 2-x Lithium manganese oxides such as O4 (where x is between 0 and 0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiV3O4, V2O5, Cu2V2O7; Ni-site type lithium nickel oxide represented by the chemical formula LiNi1-xMxO2 (where M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and x = between 0.01 and 0.3); and LiMn 2-x M x Lithium manganese composite oxides represented by O2 (where M = Co, Ni, Fe, Cr, Zn, or Ta, and x = 0.01 or greater and 0.1 or less) or Li2Mn3MO8 (where M = Fe, Co, Ni, Cu, or Zn); LiMn2O4 in which part of the Li in the chemical formula is substituted with an alkaline earth metal ion; disulfide compounds; Fe2(MoO4)3, etc., can be composed of these, but are not limited to these.

[0034] The conductive material can usually be added in an amount of 0.1 to 30% by weight based on the total weight of the mixture containing the positive electrode active material. Such conductive materials are not particularly limited as long as they do not cause chemical changes in the battery and are conductive, and for example, graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and summer black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives can be used.

[0035] The binder contained in the positive electrode is a component that assists in the bonding of the active material to the conductive material and to the current collector, and is usually added at a concentration of 0.1 to 30% by weight based on the total weight of the mixture containing the positive electrode active material. The addition of the binder can also increase the bonding strength between the positive electrode and the solid electrolyte. The solid electrolyte can also be distributed within the positive electrode. The binder according to the present invention is not particularly limited in this invention, and known methods can be used. It may be any one selected from the group consisting of polyamide-imide (PAI), polyimide (PI), polyamide (PA), polyamic acid, polyethylene oxide (PEO), polystyrene (PS), PEP-MNB (poly(ethylene-copropyleneco-5-methylene-2-norbornene)), VDF (polyvinylidene fluoride), PVDF-HFP (poly(vinylidene fluoride-co-hexafluoropropylene)), PS-NBR (polystyrene nitrile-butadiene rubber), PMMANBR (poly(methacrylate)nitrile-butadiene rubber) and mixtures thereof, or a mixture of two or more of these.

[0036] The surface of the positive electrode active material can be coated with a substance such as LiNbO3 to form a buffer layer. The buffer layer can be formed with a buffer layer-forming material of 10 nm or less to suppress the interfacial resistance between the positive electrode and the solid electrolyte.

[0037] The aforementioned secondary battery structure is illustrative and is described exemplarily to aid in understanding this disclosure. This disclosure is for cutting lithium metal used in the negative electrode. The lithium metal cutting system for the negative electrode according to this disclosure will be described below with reference to the accompanying drawings.

[0038] Figure 1 shows a lithium metal cutting system for a negative electrode according to one embodiment of the present invention.

[0039] Referring to Figure 1, the lithium metal cutting system may include a lithium metal supply unit, a lithium metal transfer unit, and a lithium metal cutting unit. The lithium metal supply unit may include lithium metal (100) and a winding roller (110) on which the lithium metal (100) is wound. The lithium metal transfer unit may include a first roller (200a), a second roller (200b), and a third roller (200c). A first refrigerant pipe (300a) may be formed inside the first roller (200a), a second refrigerant pipe (300b) may be formed inside the second roller (200b), and a third refrigerant pipe (300c) may be formed inside the third roller (200c). The lithium metal cutting unit may include a cutting member (400) and a cutting stage (500). A cutting refrigerant pipe (510) may be formed inside the cutting stage (500).

[0040] The lithium metal supply unit is configured to supply lithium metal to the lithium metal cutting unit, and the winding roller (110) can unwind a continuous film-like lithium metal that is not cut. A refrigerant pipe (not shown) through which a refrigerant flows can be placed inside the winding roller (110). This cools the lithium metal wound on the winding roller (110) and prevents it from adhering to the lithium metal transport unit or the lithium metal cutting unit due to its low tensile strength during the transport process. In other words, the refrigerant flowing through the refrigerant pipe (not shown) inside the winding roller (110) cools the lithium metal and increases its tensile strength.

[0041] The type of refrigerant is not limited. For example, the refrigerant may include cooling water, liquid nitrogen, and liquid helium. However, this is illustrative, and the refrigerant can be any substance without limitation as long as it can achieve the purpose of cooling the lithium metal and increasing the tensile strength of the lithium metal.

[0042] The lithium metal transfer unit can transfer lithium metal supplied from the lithium metal supply unit. The lithium metal transfer unit can transfer the lithium metal to the lithium metal cutting unit. This allows a continuous film-like lithium metal to be transferred to the lithium metal cutting unit and cut.

[0043] Furthermore, the lithium metal transfer unit can also serve to cool the lithium metal while simultaneously transferring it. The first refrigerant pipe (300a), the second refrigerant pipe (300b), and the third refrigerant pipe (300c) can each contain a refrigerant. The first refrigerant pipe (300a), the second refrigerant pipe (300b), and the third refrigerant pipe (300c) can receive the refrigerant through a passage connected to the outside. Each of the refrigerants can include the aforementioned cooling water, liquid nitrogen, and liquid helium. Also, as mentioned above, the refrigerant can be any substance without limitation as long as it can cool the lithium metal and increase its tensile strength.

[0044] The first refrigerant pipe (300a), the second refrigerant pipe (300b), and the third refrigerant pipe (300c) may each carry refrigerant at different temperatures. For example, the temperature of the refrigerant may decrease as you move towards the first refrigerant pipe (300a), the second refrigerant pipe (300b), and the third refrigerant pipe (300c). The temperatures of the first to third refrigerant pipes (300a, 300b, 300c) may gradually decrease, but the temperatures of the second and third refrigerant pipes (300b, 300c) may be lower than and the same as the temperature of the first refrigerant pipe (300a). In addition, the temperatures of the first to third refrigerant pipes (300a, 300b, 300c) can be set without limitation as long as sufficient cooling is achieved to increase the tensile strength of the lithium metal.

[0045] The first to third rollers (200a, 200b, 200c) can be positioned at different heights from each other. This allows the film-like lithium metal to be transported while remaining curved to match the positions of the first to third rollers (200a, 200b, 200c). Because the lithium metal has low tensile strength, it needs to be sufficiently cooled before reaching the lithium metal cutting section. The lithium metal cutting system according to this disclosure allows the lithium metal to be cooled relatively more by the first to third rollers (200a, 200b, 200c) by exposing a larger surface area to the lithium metal transport section through the arrangement of the first to third rollers (200a, 200b, 200c) at different heights from each other.

[0046] However, in this embodiment, the temperatures of the refrigerants supplied to the first to third refrigerant pipes (300a, 300b, 300c) may be the same.

[0047] The lithium metal cutting section can cut lithium metal transmitted in film form. The lithium metal can be positioned on the cutting stage (500). At this time, a cutting refrigerant pipe (510) is formed inside the cutting stage (500), and a refrigerant may flow through the cutting refrigerant pipe (510). The cutting refrigerant pipe (510) can receive the refrigerant through a passage connected to the outside. The refrigerant may include the aforementioned cooling water, liquid nitrogen, and liquid helium. Furthermore, as described above, the refrigerant can be any substance without limitation as long as it can cool the lithium metal and achieve the objective of increasing the tensile strength of the lithium metal. The lithium metal can be cooled again on the cutting stage (500) by the cutting refrigerant pipe (510). This allows the lithium metal to increase its tensile strength on the cutting stage (500). That is, the lithium metal can be cleanly cut by the cutting member (400). Here, clean cutting means that the lithium metal is cut without adhering to the cutting member. The temperature of the refrigerant flowing through the cut refrigerant pipe (510) may be lower than or the same as the temperature of the refrigerant flowing through the refrigerant pipe of the adjacent roller.

[0048] The cutting member (400) can be any equipment capable of cutting the lithium metal. For example, a knife, a punching press, etc., can be used as the cutting member (400).

[0049] However, in this embodiment, the refrigerant may not be supplied to the lithium metal cutting section. If the lithium metal is sufficiently cooled in the lithium metal transfer section and its tensile strength can be ensured, the lithium metal transferred to the lithium metal cutting section can be cut immediately without further cooling.

[0050] Figure 2 shows a lithium metal cutting system for a negative electrode according to another embodiment of the present invention. Figure 2 may be substantially the same as Figure 1, except that five rollers are used. Therefore, a description of the redundant configuration is omitted.

[0051] Referring to Figure 2, the lithium metal cutting system may include a lithium metal supply unit, a lithium metal transfer unit, and a lithium metal cutting unit. The lithium metal supply unit may include lithium metal (100) and a winding roller (110) on which the lithium metal (100) is wound. The lithium metal transfer unit may include a first roller (200a), a second roller (200b), a third roller (200c), a fourth roller (200d), and a fifth roller (200e). A first refrigerant pipe (300a) may be formed inside the first roller (200a), a second refrigerant pipe (300b) inside the second roller (200b), a third refrigerant pipe (300c) inside the third roller (200c), a fourth refrigerant pipe (300d) inside the fourth roller (200d), and a fifth refrigerant pipe (300e) inside the fifth roller (200e). The lithium metal cutting section may include a cutting member (400) and a cutting stage (500). A refrigerant pipe (510) can be formed inside the cutting stage (500).

[0052] A refrigerant pipe (not shown) through which a refrigerant flows can be placed inside the winding roller (110). This cools the lithium metal wound on the winding roller (110), preventing it from sticking to each other in the lithium metal supply section due to its low tensile strength during the transfer process, or from sticking to the lithium metal transfer section or the lithium metal cutting section. In other words, the refrigerant flowing through the refrigerant pipe (not shown) inside the winding roller (110) cools the lithium metal, thereby increasing its tensile strength.

[0053] The lithium metal transfer unit can also serve to cool the lithium metal while simultaneously transferring it. The first to fifth refrigerant pipes (300a, 300b, 300c, 300d, 300e) can each contain a refrigerant. The first to fifth refrigerant pipes (300a, 300b, 300c, 300d, 300e) can receive the refrigerant through a passage connected to the outside. The respective refrigerants can include the aforementioned cooling water, liquid nitrogen, and liquid helium. Furthermore, as described above, the refrigerant can be any substance without limitation as long as it can achieve the objective of cooling the lithium metal and increasing its tensile strength.

[0054] The first to fifth refrigerant pipes (300a, 300b, 300c, 300d, 300e) may each carry refrigerant at different temperatures. For example, the temperature of the refrigerant may decrease as you move from the first refrigerant pipe (300a) to the fifth refrigerant pipe (300e). The temperatures of the first to fifth refrigerant pipes (300a, 300b, 300c, 300d, 300e) may decrease sequentially and gradually, but the temperatures of at least some of the refrigerant pipes may be the same. In addition, the temperatures of the first to fifth refrigerant pipes (300a, 300b, 300c, 300d, 300e) can be set without restriction as long as sufficient cooling is achieved to increase the tensile strength of the lithium metal.

[0055] The first to fifth rollers (200a, 200b, 200c, 200d, 200e) can be positioned at different heights from one another. This allows the film-like lithium metal to be transported while remaining curved to match the positions of the first to fifth rollers (200a, 200b, 200c, 200d, 200e). Because the lithium metal has low tensile strength, it needs to be sufficiently cooled before reaching the lithium metal cutting section. The lithium metal cutting system according to this disclosure allows the lithium metal to be cooled relatively more by the first to fifth rollers (200a, 200b, 200c, 200d, 200e) by exposing a larger surface area to the lithium metal transport section through the arrangement of the first to fifth rollers (200a, 200b, 200c, 200d, 200e) at different heights from one another.

[0056] Furthermore, the embodiment shown in Figure 2 allows for greater cooling of the lithium metal compared to the embodiment shown in Figure 1, due to the arrangement of more rollers.

[0057] However, in this embodiment, the temperatures of the refrigerants supplied to the first to fifth refrigerant pipes (300a, 300b, 300c, 300d, 300e) may be the same.

[0058] The lithium metal cutting section can cut lithium metal transmitted in film form. The lithium metal can be positioned on the cutting stage (500). At this time, a cutting refrigerant pipe (510) is formed inside the cutting stage (500), and refrigerant may flow through the cutting refrigerant pipe (510). The cutting refrigerant pipe (510) can receive the supply of refrigerant through a passage connected to the outside. The cutting refrigerant pipe (510) allows the lithium metal to be cooled again on the cutting stage (500). This allows the lithium metal to increase its tensile strength on the cutting stage (500). That is, the lithium metal can be cleanly cut by the cutting member (400). Here, clean cutting means that the lithium metal is cut without adhering to the cutting member. The temperature of the refrigerant flowing through the cutting refrigerant pipe (510) may be lower than or the same as the temperature of the refrigerant flowing through the refrigerant pipe of the adjacent roller.

[0059] The cutting member (400) can be any equipment capable of cutting the lithium metal. For example, a knife, a punching press, etc., can be used as the cutting member (400).

[0060] Figure 3 shows a lithium metal cutting system for a negative electrode according to another embodiment of the present invention. Figure 3 may be substantially the same as Figures 1 and 2, except that the first to nth rollers are used. Therefore, a description of the redundant configuration is omitted.

[0061] Referring to Figure 3, the lithium metal cutting system according to this disclosure is not limited by the number of rollers and can be designed in various ways. The rollers can be freely used within a range that sufficiently cools the lithium metal. For example, the first to nth rollers (200a, 200b, ..., 200n) can be used to cool the metallic lithium. Each of the first to nth rollers (200a, ..., 200n) may include a refrigerant pipe (300a, 300b, ..., 300n).

[0062] The temperature of the refrigerant flowing through the refrigerant pipes (300a, 300b, ..., 300n) may gradually decrease. That is, the temperature of the refrigerant may decrease as you move from the first refrigerant pipe (300a) to the nth refrigerant pipe (300n).

[0063] For example, if the refrigerant temperature in the first refrigerant pipe (300a) is 10°C to -10°C, the nth refrigerant pipe (300n) is set to be -40°C to -50°C. However, it is possible to make the refrigerant temperature decrease as you move from the first refrigerant pipe (300a) to the nth refrigerant pipe (300n).

[0064] It is preferable that the lithium metal (100) immediately before being cut is cooled to a temperature of approximately -10°C to -30°C. This allows the temperature of the lithium metal (100) to gradually decrease as it is transported by the rollers from room temperature, so that it reaches a temperature of -10°C to -30°C when it arrives on the cutting stage (500). The decrease in temperature of the lithium metal (100) may be at a constant rate (e.g., a specific percentage) or in increments within a certain range, and any method that ensures the temperature of the lithium metal (100) reaches a temperature range of -10°C to -30°C when it arrives on the cutting stage (500) is applicable without limitation.

[0065] If the coolant flows only to the cutting stage (500), the cooling time for the lithium metal (100) is short, and the lithium metal (100) does not become sufficiently cold. Therefore, during the process of repeatedly cutting the lithium metal (100), the cut surface is not formed smoothly. If cooling is carried out through rollers and the lithium metal (100) is transported to the cutting stage (500), the temperature of the lithium metal (100) can be lowered to the desired temperature, thus enabling the formation of a smooth cut surface.

[0066] The above description of the disclosure is illustrative and should be understood as being for the purpose of aiding the understanding of the disclosure, and not as being intended to limit the embodiments of the disclosure. Those skilled in the art will be able to appropriately modify and implement one embodiment and example of the disclosure by referring to this specification and the accompanying drawings, without departing from the technical concept of the disclosure, by omitting, changing, substituting all or part of the configuration of one embodiment and example of the disclosure, or by adding other configurations. Accordingly, the scope of protection of the disclosure should be interpreted as being within the scope of the following claims, and all technical concepts within an equivalent scope should also be interpreted as being included in the scope of the disclosure.

[0067] All terms and expressions used herein should be understood, unless otherwise defined, in a way that is generally understood by a person of ordinary skill in the art to which this disclosure pertains. Furthermore, terms and expressions used herein should be interpreted broadly and not restrictively.

[0068] In this specification, the expression “including” does not exclude the presence or addition of one or more other components other than those mentioned.

[0069] Furthermore, in this specification, singular expressions include plural forms unless explicitly excluded from the context.

[0070] The following are preferred embodiments to aid in understanding the present invention, but these embodiments are provided to make the present invention easier to understand and are not limited thereto.

[0071] [Examples] Example 1 Referring to Figure 1, a lithium metal supply unit was prepared, including lithium metal (100) and a winding roller (110) on which the lithium metal (100) was wound. Then, a lithium metal sheet was fed into a lithium metal transfer unit including a first roller (200a), a second roller (200b), and a third roller (200c). A first refrigerant pipe (300a) was formed inside the first roller (200a), a second refrigerant pipe (300b) was formed inside the second roller (200b), and a third refrigerant pipe (300c) was provided inside the third roller (200c). At this time, the refrigerant temperature of the first refrigerant pipe (300a) was set to -20°C, the refrigerant temperature of the second refrigerant pipe (300b) to -30°C, and the refrigerant temperature of the third refrigerant pipe (300c) to -40°C. After this, the lithium metal sheet was transferred to the lithium metal transfer unit at a speed of 1 cm / s. Afterward, the lithium metal sheet, cooled to -20°C, was cut with a knife.

[0072] Example 2 The lithium metal sheet was cut in the same manner as in Example 1, except that the refrigerant temperature of the first refrigerant pipe (300a) to the third refrigerant pipe (300c) was set to -30°C.

[0073] Comparative Example 1 The lithium metal sheet was cut in the same manner as in Example 1, except that a lithium metal transfer section without refrigerant pipes was used and a cooling process was omitted.

[0074] Comparative Example 2 The lithium metal sheet was cut in the same manner as in Example 1, except that instead of using refrigerant pipes, the lithium metal sheet was cooled by supporting it in liquid nitrogen for 10 seconds using a conventional liquid nitrogen cooling method.

[0075] Experimental Example 1: Cross-sectional evaluation of lithium metal sheets Cross-sections of the lithium metal sheets produced in the examples and comparative examples were photographed and are shown in Figures 4 to 7. The top of each figure shows a photograph of the upper part of the cross-section taken with an optical microscope, and the bottom shows the illuminance of the lithium metal sheet cross-section taken with a laser optical illuminometer.

[0076] Figure 4 shows a cross-section of the lithium metal sheet manufactured in Comparative Example 1 without a cooling process, confirming that the cut surface is not smooth.

[0077] Figure 5 shows a cross-section of the lithium metal sheet produced in Comparative Example 2, which was supported in liquid nitrogen and cooled. It was confirmed that the cut surface was smooth.

[0078] Figure 6 shows a cross-section of a lithium metal sheet manufactured in Example 1, which was cooled by setting the temperature of the refrigerant pipe to gradually decrease. It was confirmed that the cut surface was smoother than that of the conventional liquid nitrogen cooling method.

[0079] Figure 7 shows a cross-section of the lithium metal sheet manufactured in Example 2, which was cooled to the same temperature as the refrigerant pipe. It was confirmed that the cross-section was slightly less smooth compared to Example 1.

[0080] Each embodiment described herein can be combined with others, and, insofar as it does not contradict the other, what is described in one embodiment can be similarly applied to other embodiments, even if it is not described in another embodiment. [Explanation of Symbols]

[0081] 100: Lithium metal 110: Winding roller 200a, 200b, 200c, 200d, 200e: Rollers 1 to 5 300a, 300b, 300c, 300d, 300e: 1st to 5th refrigerant pipes 400: Cutting member 500: Cutting Stage 510: Cutting refrigerant pipe

Claims

1. Lithium metal supply unit that supplies lithium metal; A lithium metal transfer unit for transferring the lithium metal supplied from the lithium metal supply unit; and It includes a lithium metal cutting unit for cutting the lithium metal transferred by the lithium metal transfer unit, The lithium metal transfer unit is Multiple rollers; and This includes a refrigerant pipe positioned inside each of the aforementioned multiple rollers, A lithium metal cutting system for negative electrodes, characterized in that the lithium metal is cooled to a temperature of -10°C to -30°C just before it is finally cut.

2. A refrigerant is supplied to the refrigerant pipe of each of the plurality of rollers. The lithium metal cutting system for a negative electrode according to claim 1, characterized in that the temperature of the refrigerant decreases as you move from the lithium metal supply unit towards the lithium metal cutting unit.

3. The lithium metal cutting system for a negative electrode according to claim 2, characterized in that the temperature of the refrigerant gradually decreases.

4. The lithium metal cutting section includes a cutting stage, The lithium metal cutting system for a negative electrode according to claim 2, characterized in that a cutting refrigerant pipe is arranged inside the lithium metal cutting stage.

5. The refrigerant is also supplied inside the cut refrigerant pipe. The lithium metal cutting system for a negative electrode according to claim 4, characterized in that the temperature of the refrigerant supplied to the inside of the cutting refrigerant pipe is lower than or equal to the temperature of the refrigerant supplied to the adjacent refrigerant pipe.

6. The lithium metal cutting system for a negative electrode according to claim 1, characterized in that at least some of the plurality of rollers are arranged at different heights from one another.

7. The lithium metal supply unit includes a winding roller for winding up the lithium metal. The lithium metal cutting system for a negative electrode according to claim 1, characterized in that a refrigerant is supplied inside the winding roller.

8. A refrigerant is supplied to the refrigerant pipe of each of the plurality of rollers. A lithium metal cutting system for a negative electrode according to any one of claims 1 to 7, characterized in that the temperatures of the refrigerants are the same.

9. The temperatures of the refrigerants are the same, The refrigerant is also supplied inside the cut refrigerant pipe. The lithium metal cutting system for a negative electrode according to claim 4 or 5, characterized in that the temperature of the refrigerant supplied to the inside of the cutting refrigerant pipe is lower than or equal to the temperature of the refrigerant supplied to the adjacent refrigerant pipe.

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