Method for processing lithium metal of negative electrode in electrode assembly

Abstract

Provided is a method for processing lithium metal of a negative electrode in an electrode assembly. The processing method includes: a supply step of separating a first raw material composed of lithium metal having a first protective layer bonded to one surface thereof and a second raw material composed of a second protective layer to supply the raw material so that the lithium metal is positioned between the first protective layer and the second protective layer; a cutting step of pressing the supplied raw materials using a cutter on the first and second protective layers to cut the lithium metal; and a recovery step of separating the first raw material and the second raw material after cutting to recover the raw material. The method for processing lithium metal according to an embodiment of the present invention is effective in processing lithium metal extending in the longitudinal direction applied as a negative electrode to a stack-folding type electrode assembly, and can produce processed lithium metal with high reliability.

Description

Method for processing lithium metal for negative electrode of electrode assembly

[0001] The present invention relates to a method for processing lithium metal for use as a negative electrode of an electrode assembly. Specifically, the present invention relates to a method for processing lithium metal that extends in the longitudinal direction and is applied as a negative electrode in a stack-folding type electrode assembly.

[0002] This application claims the benefit of priority from Republic of Korea Patent Application No. 10-2023-0166957, dated November 27, 2023, and all contents of that Republic of Korea patent application are incorporated herein by reference.

[0003] Interest in energy storage technology has been growing steadily. As applications expand to include energy storage for mobile phones, camcorders, laptops, and even electric vehicles, research and development efforts on batteries are becoming increasingly concrete. Electrochemical devices are receiving the most attention in this regard, and with the recent trend toward miniaturization and weight reduction in electronic devices, the development of secondary batteries, which are compact, lightweight, and capable of high-capacity recharge and discharge, is becoming a focus of interest.

[0004] Additionally, secondary batteries are also classified based on the structure of the electrode assembly of the positive electrode / separator / cathode structure. Representative examples of electrode assemblies include jelly-roll electrode assemblies, which are structures in which long sheet-shaped positive and negative electrodes are rolled up with a separator between them, and stacked electrode assemblies, which are structures in which multiple positive and negative electrodes cut into units of a predetermined size are sequentially stacked with a separator between them.

[0005] However, these conventional electrode assemblies have several problems.

[0006] First, the jelly-roll electrode assembly is made by tightly winding long sheet-shaped positive and negative electrodes into a cylindrical or oval cross-section. In this structure, stress caused by expansion and contraction of the electrodes during charging and discharging accumulates inside the electrode assembly, and when the stress accumulation exceeds a certain limit, deformation of the electrode assembly occurs. Furthermore, the deformation of the electrode assembly may cause an uneven gap between the electrodes, which may rapidly reduce the performance of the battery and lead to a problem of threatening the safety of the battery due to an internal short circuit. In addition, since the jelly-roll electrode assembly must wind long sheet-shaped positive and negative electrodes, it is difficult to quickly wind the assembly while maintaining a constant gap between the positive and negative electrodes, which also leads to a problem of reduced productivity.

[0007] Second, the stacked electrode assembly requires sequentially stacking a plurality of positive and negative electrode units. This requires a separate transfer process for the electrode plates for manufacturing the units, and the sequential stacking process requires significant time and effort, resulting in low productivity.

[0008] To solve these problems, an advanced stack-folding electrode assembly, which is a hybrid of the jelly-roll type and the stack type, has been developed. The stack-folding electrode assembly has a structure in which bi-cells or full cells, which are stacked with a separator interposed between a predetermined number of positive and negative electrodes, are wound using a long, continuous separator sheet (folding separator).

[0009] The above stack-folding type electrode assembly generally connects the electrodes of each layer by extending a separator, which is easier to fold than the electrodes. At this time, the electrodes of each layer are supplied in a cut state for forming the electrode assembly, similar to the stack-type electrode assembly. In the relevant technical field, when a secondary battery is composed only of materials that are easy to cut or not easy to fold among the various electrode materials that constitute the secondary battery, such a general stack-folding type electrode assembly is more suitable. On the other hand, lithium metal, which is well known as an anode material of secondary batteries in the relevant technical field, has physical properties such as high ductility and viscosity, making it difficult to process, such as cutting, and is relatively easy to fold, and thus may not be suitable for the existing stack-folding type electrode assembly.

[0010] Currently, various studies are being conducted on a new type of stack-folding electrode assembly, which is manufactured using only one negative electrode structure having a longitudinally extended shape by sandwiching the negative electrode lithium metal between two separators. The inventors of the present invention have completed the present invention by studying a method for effectively processing lithium metal applicable to the above-described new type of stack-folding electrode assembly.

[0011] [Prior Art Literature]

[0012] [Patent Document]

[0013] (Patent Document 1) Korean Patent No. 10-2022-0035741

[0014] The present invention seeks to provide a method for processing a longitudinally extended lithium metal applied as a negative electrode in a stack-folding type electrode assembly.

[0015] According to the first aspect of the present invention,

[0016] The present invention provides a method for processing lithium metal for a negative electrode of an electrode assembly.

[0017] In one specific embodiment of the present invention, the method comprises a supply step of separating a first raw material composed of lithium metal having a first protective layer bonded to one surface and a second raw material composed of a second protective layer, and supplying the raw material so that the lithium metal is positioned between the first protective layer and the second protective layer; a cutting step of pressing the supplied raw material with a cutter on the first protective layer and the second protective layer to cut the lithium metal; and a recovery step of separating the first raw material and the second raw material after the cutting to recover the raw material.

[0018] In one specific example of the present invention, the first raw material is supplied and recovered by a first roll set, the second raw material is supplied and recovered by a second roll set, and each of the first roll set and the second roll set is composed of a plurality of rolls capable of moving the raw material.

[0019] In one specific example of the present invention, the first protective layer and the second protective layer are polymer protective films made of different materials.

[0020] In one specific example of the present invention, the first protective layer is a polyolefin-based polymer protective film.

[0021] In one specific example of the present invention, the second protective layer is a polyester-based polymer protective film.

[0022] In one specific example of the present invention, in the cutting step, the first raw material and the second raw material are positioned apart from each other before being pressed by the cutting machine.

[0023] In one specific embodiment of the present invention, the cutter is composed of a cutting portion and a supporting portion, and the cutting portion and the supporting portion are positioned on opposite sides with respect to the lithium metal.

[0024] In one specific embodiment of the present invention, the cutting portion includes a protruding cutting blade, and the cutting portion moves toward the support portion to pressurize the raw material to cut the lithium metal.

[0025] In one specific example of the present invention, the internal space between the protruding cutting blades and the cutting blades in the cutting section is filled with a cushioning material.

[0026] In one specific example of the present invention, the lithium metal is cut by the pressure of a protruding cutting blade and ultrasonic waves.

[0027] In one specific example of the present invention, each of the first roll set and the second roll set includes a dancer roll capable of controlling the tension of a raw material running on the rolls, and by the dancer roll, the first raw material running on the first roll set and the second raw material running on the second roll set have different tensions.

[0028] In one specific example of the present invention, the first raw material running in the first roll set has a tension of 20 N / m to 40 N / m.

[0029] In one specific example of the present invention, the second raw material running in the second roll set has a tension of 40 N / m to 60 N / m.

[0030] In one specific example of the present invention, the tension of the first raw material is reduced by 10% to 20% when in contact with the cutter compared to when in motion.

[0031] In one specific embodiment of the present invention, the cutting step cuts lithium metal to form a tab.

[0032] In one embodiment of the present invention, the cutting step cuts lithium metal to form tabs and chamfers.

[0033] In one specific embodiment of the present invention, a pair of tabs adjacent to the chamfer are spaced an equal distance from the chamfer.

[0034] In one embodiment of the present invention, the tab is positioned closer to one of a pair of adjacent chamfers relative to the tab.

[0035] In one specific example of the present invention, when an area divided by four chamfers is viewed as one unit area, the cutter cuts two or more unit areas at a time.

[0036] In one specific example of the present invention, through the cutting step, a unit area without a tab is manufactured, and the unit area without a tab is manufactured by moving only one unit area after cutting and then performing a duplicate cut.

[0037] In one specific embodiment of the present invention, in the recovery step, the cut lithium metal pieces of the first raw material are removed.

[0038] In one specific example of the present invention, the first raw material from which lithium metal pieces have been removed in the recovery step is recovered by separating it into processed lithium metal and the first protective layer.

[0039] In one specific example of the present invention, the cutting blade has an asymmetrical shape on both sides based on the end of the cutting blade.

[0040] In one specific example of the present invention, the process of separating the first raw material and the second raw material in the recovery step is monitored through a sensor.

[0041] In one specific example of the present invention, when the lithium metal and the second protective layer come into contact, the cutting blade generates ultrasonic waves.

[0042] A method for processing lithium metal according to one specific example of the present invention is effective in processing lithium metal extended in the longitudinal direction to be applied as a negative electrode in a stack-folding type electrode assembly, and can produce a processed lithium metal with high reliability.

[0043] According to the above lithium metal processing method, the processing speed is improved through a continuous process, and defects such as lithium metal sticking to the processing device or wrinkles occurring in the manufactured lithium metal can be minimized, so the above lithium metal processing method can be suitable for mass production.

[0044] FIG. 1 is a schematic drawing showing the structure of an electrode assembly including a cathode structure with lithium metal interposed between two separators and a cathode according to one specific example of the present invention.

[0045] FIG. 2 is a schematic diagram illustrating the structure of lithium metal processed for application to an electrode assembly according to one specific example of the present invention. In FIG. 2, the lithium metal has tabs formed in each layer, and the positions corresponding to the stack portions are illustrated.

[0046] FIG. 3 is a schematic diagram illustrating the structure of lithium metal processed for application to an electrode assembly according to one specific example of the present invention. The lithium metal in FIG. 3 is divided into a portion with tabs and a portion without tabs, with the portion with tabs illustrating a position corresponding to a stack portion and the portion without tabs illustrating a position corresponding to a wrapping portion.

[0047] FIG. 4 is a schematic drawing of a structure of a device capable of implementing a method for processing lithium metal according to one specific example of the present invention.

[0048] FIG. 5 is an enlarged view of a cutting position in a lithium metal processing device according to one specific example of the present invention.

[0049] Fig. 6 is a schematic diagram illustrating a cutting process of lithium metal according to one specific example of the present invention. Fig. 6(a) shows the position of the cut portion before cutting, and Fig. 6(b) shows the position of the cut portion during cutting.

[0050] FIG. 7 is a schematic drawing of a cutting part including a cutting blade and a buffer material according to one specific example of the present invention.

[0051] FIG. 8 is a drawing schematically showing the shape of the tip of a cutting blade in a cutting section according to one specific example of the present invention.

[0052] Hereinafter, specific examples will be described in detail with illustrative drawings. When assigning reference numerals to components in each drawing, it should be noted that, where possible, identical components will be assigned the same reference numerals, even if they appear in different drawings. Furthermore, when describing specific examples, if a detailed description of a related known configuration or function is deemed to hinder understanding of the specific example, such detailed description will be omitted.

[0053] Additionally, terms such as first, second, A, B, (a), (b), etc. may be used to describe components of a specific example. These terms are only intended to distinguish the components from other components, and the nature, order, or sequence of the components are not limited by the terms. When a component is described as being "connected," "coupled," or "connected" to another component, it should be understood that the component may be directly connected or connected to the other component, but another component may also be "connected," "coupled," or "connected" between each component.

[0054] Components included in one specific example and components with common functions will be described using the same names in other specific examples. Unless otherwise stated, the descriptions given in one specific example may also apply to other specific examples, and specific descriptions will be omitted to the extent of overlap.

[0055]

[0056] The present invention relates to a method for processing lithium metal for use as an anode of an electrode assembly. According to one embodiment of the present invention, the lithium metal processing method may be suitable for processing lithium metal applied to a novel stack-folding electrode assembly. The novel stack-folding electrode assembly may be, for example, an electrode assembly manufactured using only one anode structure in which the lithium metal of the anode is sandwiched between two separators. Such an electrode assembly is characterized by the use of lithium metal that is sufficiently extended in the longitudinal direction. Due to its ductility and high viscosity, lithium metal is not easily processed, such as by cutting. Furthermore, longer lithium metals are more difficult to handle, which may result in defects occurring during or before or after the processing. The term "processing" herein refers to the process of converting lithium metal supplied as a raw material into a specification suitable for application to an electrode assembly, wherein the lithium metal may be cut to form tabs. According to the lithium metal processing method according to one embodiment of the present invention, defects, such as lithium metal sticking to a processing device or wrinkles occurring in the manufactured lithium metal, can be minimized.

[0057] In this specification, the terms “length direction,” “width direction,” and “thickness direction” (or “height direction”) are used. In this specification, drawings such as FIGS. 1, 4, 5, and 6 are front views, and based on the front views, the “length direction” means the left-right direction in the drawings, the “width direction” means the front-back direction in the drawings, and the “thickness direction” (or “height direction”) means the up-down direction in the drawings. In this specification, drawings such as FIGS. 2 and 3 are plan views, and drawings such as FIG. 7 are bottom views, and based on the plan views and bottom views, the “length direction” means the left-right direction in the drawings, the “width direction” means the up-down direction in the drawings, and the “thickness direction” (or “height direction”) means the front-back direction in the drawings.

[0058] In this specification, the term "adjacent" refers to the object closest to the reference among multiple objects. If multiple objects are located on either side of the reference, adjacent objects are selected for each direction. Adjacent objects do not necessarily touch the reference.

[0059] The term "bonding" in this specification refers to two materials being in contact with a certain degree of adhesiveness. For example, the first raw material exists with a first protective layer bonded to one surface of lithium metal, meaning that the lithium metal is in contact with the first protective layer with a certain degree of adhesiveness, and the first protective layer can be separated from the lithium metal as needed.

[0060]

[0061] To facilitate understanding of the present invention, a novel stack-folding electrode assembly suitable for application of lithium metal processed by the lithium metal processing method of the present invention will first be described in detail. The stack-folding electrode assembly described below is merely an example, and the lithium metal processing method according to one specific embodiment of the present invention can be effectively applied when processing lithium metal extending in the longitudinal direction.

[0062] The above stack-folding electrode assembly includes a positive electrode, a negative electrode, and a separator. In the electrode assembly, the positive electrode and the separator are not particularly limited as long as they are materials commonly used in the relevant technical field, but lithium metal is used as the negative electrode. In the present specification, lithium metal may be broadly interpreted as long as it does not have significant physical properties compared to lithium metal, even if some components are added to lithium or it is in the form of an alloy with some metal, and thus the same problems may occur when applied to a conventional electrode assembly as lithium metal. In the present specification, the negative electrode may be referred to as a lithium metal layer because it includes lithium metal, and the negative electrode and the separator may be referred to as an negative electrode structure because they are supplied as a single, integrated configuration.

[0063] The above negative electrode is sandwiched between two separators to form a negative electrode structure. The negative electrode structure has a structure extending in the longitudinal direction, and the electrode assembly includes only one negative electrode structure. The basic electrode assembly structure is formed by folding the negative electrode structure having the structure extending in the longitudinal direction to fix the positive electrode therein. The step of sandwiching the negative electrode, lithium metal, between the two separators is a step after processing the lithium metal using a lithium metal processing method according to one specific example of the present invention. For example, the negative electrode structure can be manufactured by positioning the lithium metal between two separators and then pressing it from both sides.

[0064] The above-described negative electrode structure includes one stack initiation portion, multiple stack portions, multiple folding portions, and one wrapping portion according to a position in the electrode assembly. The stack initiation portion may be included in the stack portion as it has no special difference in function from the stack portion. When the stack initiation portion is specified, the stack portion refers to a stack portion other than the stack initiation portion. In the above-described negative electrode structure, the stack portion, the folding portion, and the wrapping portion are units that distinguish positions having different functions according to the longitudinal direction of the negative electrode structure. Here, the stack portion located at one end of the negative electrode structure is the stack initiation portion. The stack portion, the folding portion, and the wrapping portion are not distinguished by material but by position.

[0065] The above stack portion refers to a cathode structure at a position where the positive electrode is stacked, and has a mainly straight shape based on Fig. 1. The above folding portion refers to a cathode structure at a position connecting the stack portions, and has a mainly curved shape based on Fig. 1. The above wrapping portion refers to a cathode structure at a position that wraps the stacked structure of the positive and negative electrode structures from the point where the uppermost stack portion ends, and has a mixture of straight and curved shapes based on Fig. 1.

[0066] As shown in Fig. 1, the cathode structure has a stack initiation portion positioned at one end in the longitudinal direction and a wrapping portion positioned at the other end. In addition, a folding portion and a stack portion are alternately positioned between the stack initiation portion and the wrapping portion, and the stack initiation portion is in contact with the folding portion and the wrapping portion is in contact with the stack portion. Since the stack portion is substantially the same in length as the positive electrode, the length of each stack portion is substantially the same. However, the stack initiation portion positioned at the starting point of the stacked structure may have a different length from the positive electrode depending on the position of the starting point.

[0067] The above-described negative electrode structure forms an electrode assembly together with a plurality of positive electrodes. To facilitate understanding of the structure of the electrode assembly, FIG. 1 provides an exemplary structure of an electrode assembly including a negative electrode structure with lithium metal interposed between two separators, and a positive electrode. Since the negative electrode structure includes a negative electrode (110) and a separator (120), the electrode assembly (100) includes a positive electrode (130), a negative electrode (110), and a separator (120).

[0068] The electrode assembly (100) has a plurality of stack sections sequentially positioned in a thickness direction in parallel by a folding section. In addition, at least one positive electrode is positioned between stack sections adjacent to each other in the thickness direction. The electrode assembly (100) may have a structure in which the outer surface in the thickness direction and length direction is surrounded by a wrapping section or the like.

[0069] Since the stack portion and the positive electrode of the negative electrode structure are sequentially and alternately stacked inside the electrode assembly (100), the negative electrode structure including the folding portion has a zigzag shape. In other words, the folding portions sequentially positioned from the stack portion located at one end of the negative electrode structure are alternately positioned on the left or right side of the electrode assembly. If the stack portion and the positive electrode of the negative electrode structure are not alternately stacked, and two or more of the stack portions or the positive electrode are sequentially stacked, a potential difference may not occur between the sequentially stacked layers, which may lower the efficiency of the battery.

[0070] In the above electrode assembly (100), the negative electrode (110) does not include a current collector that supports lithium metal. Since the negative electrode (110) does not include a current collector, the loading amount of the negative electrode active material within the electrode assembly can be improved, thereby contributing to improved battery performance. When the negative electrode (110) is mainly composed of lithium metal, the lithium metal may not be easy to process, such as cutting, due to its high ductility and viscosity. However, in the electrode assembly (100), the negative electrode is applied in the form of a negative electrode structure in which the lithium metal (110) is sandwiched between separators (120), thereby making up for the insufficient physical properties of the lithium metal (110) within the electrode assembly.

[0071] The electrode assembly (100) may form tabs on each of the positive electrode (130) and the negative electrode (110) to electrically connect to the outside of the lithium secondary battery. The tabs may be formed in each layer, and a plurality of positive electrode tabs and a plurality of negative electrode tabs may be joined together and connected to a lead. The lead transmits electric energy generated in the lithium secondary battery to the outside. The tabs on the positive electrode (130) may be mainly formed on a non-coated portion of the current collector where the positive electrode active material is not applied. In contrast, since the tabs on the negative electrode (110) do not include a current collector that supports lithium metal, the tabs may be formed by cutting the lithium metal.

[0072] The positive electrode tab and the negative electrode tab may be formed in the same or opposite directions. As described above, since the tabs of each layer must be bonded one by one for each positive electrode tab and each negative electrode tab, the positive electrode tab is positioned to overlap each positive electrode tab in the thickness direction, and the negative electrode tab is positioned to overlap each negative electrode tab in the thickness direction. If the positive electrode tab and the negative electrode tab overlap, an electrical short circuit may occur, so the positive electrode tab and the negative electrode tab do not overlap each other in the thickness direction. Fig. 1 shows the position of the negative electrode tab (110T) formed on the lithium metal in the electrode assembly (100). The present invention has little to do with the positive electrode tab, so the positive electrode tab is not shown in Fig. 1. As shown in Fig. 1, the negative electrode tab (110T) is positioned to overlap each negative electrode tab in the thickness direction. If the positive electrode tab and the negative electrode tab are positioned in opposite directions, they do not overlap each other in the thickness direction, so the positive electrode tab and the negative electrode tab can be freely arranged in each layer. Alternatively, if the positive and negative tabs are positioned in the same direction, the positive and negative tabs may be positioned on one side of the center so as not to overlap each other.

[0073] The lithium metal (110) applied to the electrode assembly (100) may have a shape as shown in FIG. 2 or FIG. 3. FIG. 2 and FIG. 3 provide exemplary structures of lithium metal processed for application to the electrode assembly. The lithium metal (110) in FIG. 2 has tabs (110T) formed in each layer, and the positions corresponding to the stack portion are illustrated. The lithium metal (110) in FIG. 3 is divided into a portion where the tabs (110T) are formed and a portion where the tabs (110T) are not formed, and the portion where the tabs (110T) are formed shows a position corresponding to the stack portion, and the portion where the tabs (110T) are not formed shows a position corresponding to the wrapping portion.

[0074] According to one specific example of the present invention, the processed lithium metal (110) includes a chamfer (110C) together with a tab (110T). The chamfer (110C) may be positioned at a corner portion of the electrode assembly (100), and the corner portion of the electrode assembly (100) may be cut by the chamfer (110C) to form a slanted surface. The chamfer (110C) may serve as a reference for dividing each layer in the electrode assembly (100). The lithium metal (110) may be folded based on a pair of chamfers (110C) facing each other in the width direction of the lithium metal (110). Since the above chamfer (110C) can be a reference for dividing each layer, in order for the tabs (110T) to be positioned so as to overlap each other in the thickness direction in the electrode assembly (100), a pair of tabs (110T) adjacent to the chamfer (110C) can be positioned at the same position from the chamfer (110C). As shown in Fig. 3, the chamfer (110C) can also be formed uniformly in the wrapping portion. The reason why the chamfer (110C) is formed in the wrapping portion is due to the processing of lithium metal according to one specific example of the present invention, which will be described in detail below. The chamfer (110C) formed in the wrapping portion cannot be a reference for dividing each layer.

[0075]

[0076] The present invention provides a method for processing a lithium metal extending in the longitudinal direction, such as a negative electrode used in the electrode assembly described above. The method is divided into a supply step, a cutting step, and a recovery step. According to one specific embodiment of the present invention, the supply step separately supplies a first raw material composed of lithium metal having a first protective layer bonded to one surface, and a second raw material composed of a second protective layer. The supply step refers to a step up to the step of positioning the raw material in front of a cutter before the cutting step. In the raw material positioned in front of the cutter by the supply step, the lithium metal is positioned between the first protective layer and the second protective layer. Before positioning in front of the cutter, the lithium metal may not be positioned between the first and second protective layers. The fact that the lithium metal is positioned between the first and second protective layers does not mean that the lithium metal is in contact with the first and second protective layers. According to one specific embodiment of the present invention, since the first protective layer is supplied in a state of being in contact with the lithium metal, even if it is in contact with the lithium metal, the second protective layer, which is supplied separately, is positioned apart from the lithium metal. The above second protective layer can come into contact with lithium metal when cut.

[0077] According to one specific embodiment of the present invention, the cutting step pressurizes the raw material supplied through the supply step with a cutting device on the first protective layer and the second protective layer to cut the lithium metal. Here, “on the first protective layer and the second protective layer” means an opposite direction not facing the lithium metal in the first protective layer and the second protective layer. The cutting device may be composed of a cutting portion including an actual cutting means and a supporting portion not including the cutting portion. When the cutting portion is located on the first protective layer, the supporting portion may be located on the second protective layer, and when the cutting portion is located on the second protective layer, the supporting portion may be located on the first protective layer. As the cutting portion in the cutting device moves toward the supporting portion, the raw material between the cutting portion and the supporting portion may be pressed, thereby cutting the lithium metal. At this time, the first protective layer and the second protective layer may not be cut.

[0078] According to one specific embodiment of the present invention, the recovery step separates and recovers the first and second raw materials after cutting in the cutting step. Even if the first and second raw materials are separated, the recovery step requires separating the processed lithium metal and supplying it to the next step, taking into account the subsequent steps of processing the lithium metal. Here, the next step may include, for example, bonding the processed lithium metal between two separators to manufacture the anode structure described above.

[0079] According to one specific embodiment of the present invention, in the recovery step, the cut lithium metal pieces of the first raw material are removed. The lithium metal pieces refer to the portions of the lithium metal supplied as raw material that are not utilized as the negative electrode after being cut. If the lithium metal is cut to match the width of the supplied raw material when cutting, the lithium metal pieces may not be connected as one, making removal difficult. Therefore, it may be preferable to cut the lithium metal slightly inward from the width of the supplied raw material when cutting so that the lithium metal pieces are connected as one. The method for removing the lithium metal pieces from the first raw material is not particularly limited.

[0080] According to one specific embodiment of the present invention, in the recovery step, the first raw material from which lithium metal fragments have been removed is recovered by separating the processed lithium metal from the first protective layer. Even if the lithium metal fragments are recovered from the first raw material, the processed lithium metal may still be bonded to the first protective layer. Only by separating the processed lithium metal from the first protective layer can the processed lithium metal be supplied to the next step in the electrode assembly manufacturing process.

[0081] The above lithium metal processing method can be implemented by a roll processing device. According to one specific example of the present invention, the first raw material of the first roll is supplied and recovered by a first roll set, and the second raw material is supplied and recovered by a second roll set. Each of the first roll set and the second roll set is composed of a plurality of rolls capable of moving the raw material. The plurality of rolls can individually have various functions. Since the above lithium metal processing method is implemented by a roll processing device, lithium metal can be continuously processed.

[0082] To help understand the structure of the above roll processing device, FIG. 4 provides the structure of an exemplary device that can implement a method for processing lithium metal according to one embodiment of the present invention. The roll processing device includes a first roll set (210) located at the top and a second roll set (220) located at the bottom, and includes a cutter (230) for cutting lithium metal. In some cases, the first roll set may be located at the bottom of the roll processing device, and the second roll set may be located at the top of the roll processing device. The first roll set (210) and the second roll set (220) are not named according to their positions, but are determined according to the moving target. The first roll set (210) moves a first raw material including lithium metal and a first protective layer, and the second roll set moves a second raw material including a second protective layer.

[0083] The first roll set (210) includes a winder (211), a driving roll (212), and an alignment roll (213). Similarly, the second roll set (220) includes a winder (221), a driving roll (222), and an alignment roll (223). The second roll set (220) is not necessarily formed symmetrically with the first roll set (210), and its configuration can be freely adjusted depending on the type of applied material. The winders (211, 221) serve to supply or recover the first raw material or the second raw material. The first raw material and the second raw material can be supplied in a roll form and recovered in a roll form by the winders (211, 221). The driving rolls (212, 222) serve to move the first raw material and the second raw material, and are arranged between the winders (211, 221) and the alignment rolls (213, 223). The above-described driving rolls (212, 222) can determine the movement paths of the first and second raw materials, and may be composed of multiple rolls with various functions. The above-described alignment rolls (213, 223) serve to determine the positions of the first and second raw materials in front of the cutter. Here, “in front of the cutter” may mean the area between the cutting section (231) and the support section (232) of the cutter (230), as shown in FIG. 4.

[0084] The above cutter (230) includes a cutting portion (231) and a supporting portion (232). The cutting portion (231) includes a cutting means such as a cutting blade, and the supporting portion (232) supports the raw material so that it can be pressed by the movement of the cutting portion (231). In order to pressurize the raw material located between the cutting portion (231) and the supporting portion (232), the cutting portion (231) and the supporting portion (232) are positioned on opposite sides with respect to lithium metal. The cutting portion (231) may be positioned on the upper side of the raw material, and the supporting portion (232) may be positioned on the lower side of the raw material, or vice versa in some cases.

[0085] To help understand the position where the lithium metal is cut in the above-described roll processing device, FIG. 5 provides an enlarged drawing of the cutting position in the processing device of the lithium metal according to one embodiment of the present invention. According to FIG. 5, the first raw material and the second raw material are separated by the alignment rolls (213, 223) and placed between the cutting portion (231) and the support portion (232). The first raw material is supplied in a state where the first protective layer (111) is bonded to one surface of the lithium metal (110), and at this time, the lithium metal (110) is located between the first protective layer (111) and the second protective layer (112). In the cutting device (230), the cutting portion (231) is located at the upper end of the first protective layer (111), and the support portion (232) is located at the lower end of the second protective layer (112). According to one specific example of the present invention, the cutting portion (231) includes a cutting blade (231K) protruding toward the first protective layer (111). The cutting blade (231K) may protrude by an appropriate length for cutting the lithium metal (110) between the first protective layer (111) and the second protective layer (112), for example, 0.5 mm to 3 mm, 1 mm to 2 mm, and specifically, about 1.5 mm.

[0086] Before pressurizing with a cutter (230), it is preferable that the first raw material and the second raw material are positioned apart from each other. The first raw material is composed of a first protective layer (111) and lithium metal (110), and the second raw material is composed of a second protective layer (112). The second protective layer (112) serves to protect the lithium metal (110) from sticking to the cutter (230) during cutting. The second protective layer (112) adheres to the lithium metal (110) only during cutting, and it is advantageous to position the first raw material and the second raw material apart from each other in order to be easily detached. According to one specific example of the present invention, in the cutting step, the first raw material and the second raw material are positioned apart from each other by 5 cm or more before pressurizing with a cutter. Specifically, the distance between the first raw material and the second raw material may be 5 cm or more, 5 cm to 20 cm, or 5 cm to 15 cm. At the above-mentioned distance, attachment and detachment of the second protective layer (112) through cutting can be facilitated.

[0087] To help understand the process of cutting lithium in the above-described roll processing device, FIG. 6 provides a schematic diagram of a cutting process of lithium metal according to an embodiment of the present invention. Specifically, FIG. 6(a) shows the position of the cutting portion before cutting, and FIG. 6(b) shows the position of the cutting portion during cutting. As shown in FIG. 6, the cutting portion (231) can move toward the support portion (232) to pressurize the raw material and cut the lithium metal (110). Moving the cutting portion (231) rather than the support portion (232) can make the cutting position clearer and can be advantageous for detaching the lithium metal (110) from the second protective layer (112) after cutting. After the cutting is completed, the cutting portion (231) returns to its original position, so that the lithium metal (110) is detached and separated from the second protective layer (112).

[0088] For cutting, when the cutting part (231) moves toward the support part (232), the protruding cutting blade (231K) pulls and moves the first raw material while making contact with the first protective layer (111). The sharp cutting blade (231K) may have difficulty transmitting sufficient force to pull and move the first raw material because the contact area with the first protective layer (111) is small. In addition, when cutting, if only the cutting blade (231K) portion protrudes, defects such as wrinkles forming in the lithium metal located inside the cutting blade (231K) may occur. According to one specific example of the present invention, the internal space between the protruding cutting blade (231K) and the cutting blade (231K) in the cutting part (231) is filled with a buffer material. To help understand the position of the buffer material in the cutting part (231), FIG. 7 provides a drawing schematically showing a cutting part including a cutting blade and a buffer material according to one specific example of the present invention. The above drawing 7 shows a shape of the cut portion (231) when viewed from the first protective layer (111) to clearly indicate the position of the buffer material (231F). The buffer material (231F) is not particularly limited as long as it has a supporting force that does not interfere with cutting by the cutting blade (231K) while pressing the first protective layer (111) to a certain extent. For example, a sponge can be used as the buffer material (231F). In order to increase cutting efficiency, ultrasonic waves can be applied to the cutting blade (231K), and stress resulting from ultrasonic cutting can be alleviated in the area where the buffer material (231F) is located.

[0089] According to one specific example of the present invention, the lithium metal (110) is cut by the pressure of a protruding cutting blade (231K) and ultrasonic waves. When ultrasonic waves are applied to the cutting blade (231K), cutting efficiency can be increased. According to one specific example of the present invention, when the lithium metal (110) and the second protective layer (112) come into contact, ultrasonic waves are irradiated through the cutting blade (231K). As described above, when the cutting part (231) moves toward the support part (232) for cutting, the protruding cutting blade (231K) may move while pulling the first raw material while in contact with the first protective layer (111). If the cutting blade irradiates ultrasonic waves at this time, the lithium metal may be damaged during the movement. According to one specific example of the present invention, the irradiation depth of the ultrasonic waves is 50% to 150%, 55% to 140%, and 60% to 130% of the sum of the thicknesses of the first raw material and the second raw material. The irradiation depth of the ultrasonic waves refers to the distance from the cutting blade (231K) to the location where the ultrasonic waves are transmitted.

[0090] According to one specific example of the present invention, the cutting blade (231K) has an asymmetrical shape on both sides based on the end of the cutting blade (231K). To help understand the shape of the end of the cutting blade (231K), FIG. 8 provides a drawing schematically showing the shape of the end of the cutting blade in a cutting section according to one specific example of the present invention. That the cutting blade (231K) has an asymmetrical shape means that the angles (a1, a2) from the horizontal line tangent to the end of the cutting blade to the cutting are different on both sides, as shown in the broken line in FIG. 8. Since the cutting blade (231K) has an asymmetrical shape, even if the thickness of the cutting blade (231K) is thick, excellent cutting efficiency can be maintained. If the thickness of the cutting blade (231K) is thickened, the durability of the cutting blade (231K) can be improved. The cutting blade (231K) can be positioned so that the larger side (a1) of the two angles of the cutting blade (231K) faces the processed lithium metal, and the smaller side (a2) faces the lithium metal piece. The angle (a1) of the larger side of the cutting blade can be close to 90 degrees. Cutting the lithium metal piece with the cutting blade with the smaller angle can facilitate the removal of the lithium metal piece.

[0091] In order to increase the processing efficiency of the lithium metal (110), the first protective layer (111) and the second protective layer (112) may use polymer films made of different materials. The first protective layer (111) moves in a bonded state with the lithium metal from supply to recovery, and since it directly contacts the cutting blade (231K) of the cutting part during cutting, it requires a different functionality from the second protective layer (112) that is briefly bonded to the lithium metal during cutting and then separated.

[0092] According to one specific example of the present invention, the first protective layer (111) is a polyolefin-based polymer protective film. The polyolefin-based polymer protective film may be, for example, a polyethylene protective film or a polypropylene protective film. The polyolefin-based polymer protective film has a certain degree of adhesiveness with the lithium metal (110) and can serve to support the lithium metal (110) when the lithium metal (110) moves between rolls. In addition, the polyolefin-based polymer protective film has an appropriate level of durability, so that the lithium metal (110) is not cut even when pressure is applied with a cutting blade (231K) to cut the lithium metal. In addition, the polyolefin-based polymer protective film does not have an excessively high release peeling force with respect to the lithium metal, so that the lithium metal (110) can be separated without damage during the recovery process.

[0093] According to one specific example of the present invention, the second protective layer (112) is a polyester-based polymer protective film. The polyester-based polymer protective film may be, for example, a polyethylene terephthalate protective film. The polyester-based polymer protective film has sufficient durability to support the lithium metal (110) during cutting, while also being capable of separating the lithium metal (110) without damage after cutting.

[0094] In the present invention, the first raw material and the second raw material may have an appropriate thickness in consideration of their respective functionality. According to one specific example of the present invention, the thickness of the lithium metal (110) constituting the first raw material is 10 µm to 90 µm, 20 µm to 80 µm, or 30 µm to 70 µm. The thickness of the lithium metal (110) may be appropriately adjusted in consideration of the specifications of the electrode assembly to which it is applied. According to one specific example of the present invention, the thickness of the first protective layer (111) constituting the first raw material is 10 µm to 50 µm, 15 µm to 45 µm, or 20 µm to 40 µm. Within the above-described thickness range, the first protective layer (111) can secure sufficient functionality in the processing of the lithium metal (110) according to one specific example of the present invention. According to one specific example of the present invention, the thickness of the second protective layer (112) constituting the second raw material is 50 µm to 100 µm, 55 µm to 95 µm, or 60 µm to 90 µm. Within the above-described thickness range, the second protective layer (112) can secure sufficient functionality in processing lithium metal (110) according to one specific example of the present invention.

[0095] Since the first protective layer (111) and the second protective layer (112) must ultimately be separated from the lithium metal (110), the release peel strength with respect to the lithium metal (110) can be an important criterion for selecting a material. Since the second protective layer (112) is only briefly bonded to the lithium metal (110) when cut and must be immediately separated from the lithium metal (110) thereafter, the release peel strength of the second protective layer (112) with respect to the lithium metal (110) may be lower than that of the first protective layer (111). According to one specific example of the present invention, the second protective layer (112) has a release peel strength of 20 gf / in or less, 5 gf / in to 20 gf / in, 6 gf / in to 17 gf / in, 7 gf / in to 15 gf / in, or 8 gf / in to 12 gf / in. The above release peel strength can be measured according to ASTM D3330 standard. For example, the release peel strength refers to the force to peel the release film, which is attached to a Tesa7475 standard adhesive tape by pressing it back and forth three times with a load of 2 kg, stored at a temperature of 25°C for 24 hours, and then measured according to the peeling speed using a measuring device (AR-1000, Chem Instrument Co.) at a temperature of 25°C. Specifically, the release peel strength can be measured at a peeling speed of 0.3 m / min in an atmosphere of 25°C and 50% RH after stored for 24 hours. According to one specific example of the present invention, the release peel strength of the first protective layer (111) is greater than the release peel strength of the second protective layer (112). Specifically, the release strength of the first protective layer (111) is greater than 1, 1.1, 1.2, 1.3, 1.4, or more, and less than 2, 1.9, 1.8, 1.7, or less, and 1.6 times the release strength of the second protective layer (112), and may be greater than 1 and less than 2, 1.2 to 1.9, or 1.4 to 1.8 times the release strength of the second protective layer (112).The difference in the peel strength between the first protective layer (111) and the second protective layer (112) is due to the difference in functionality between the first protective layer (111) and the second protective layer (112).

[0096] The first protective layer (111) or the second protective layer (112) may form a coating layer on the surface that comes into contact with the lithium metal (110) to add functionality such as a release strength. The coating layer is not particularly limited as long as it secures the functionality required for the present invention. According to one specific example of the present invention, the coating layer includes silicon. It may be more preferable that the coating layer be applied to the second protective layer (112).

[0097] In a lithium metal processing method according to one embodiment of the present invention, the first raw material and the second raw material can be supplied and recovered in different states. The first raw material and the second raw material running in the lithium metal processing device (200) can have different tensions. In a roll processing device, which is one embodiment of the lithium metal processing device (200), each of the first roll set (210) and the second roll set (220) includes a dancer roll that can adjust the tension of the raw material running on the roll. The dancer roll can be one or more of the running rolls (220) in FIG. 4, and adjusts the tension of the raw material by moving the roll body.

[0098] According to one specific example of the present invention, the first raw material running on the first roll set (210) has a tension of 20 N / m to 40 N / m, 25 N / m to 40 N / m, 25 N / m to 35 N / m. According to one specific example of the present invention, the second raw material running on the second roll set (220) has a tension of 40 N / m to 60 N / m, 45 N / m to 60 N / m, 45 N / m to 55 N / m. The tension may be determined by a value indicated on the roll processing device (Manufacturer: ARISE, Product Name: W500). The lithium metal included in the first raw material basically cannot increase the tension due to its physical properties. The tension range of the first raw material described above is a possible value by bonding the lithium metal (110) to the first protective layer (111). However, if the tension is increased excessively, the lithium metal (110) in the first raw material may be damaged. In contrast, since the second raw material is composed only of the second protective layer (112) without lithium metal, the tension can be set higher.

[0099] When cutting lithium metal (110), as shown in FIG. 6, as the cutting part (231) moves toward the support part (232), the first raw material in contact with the cutting blade also moves toward the second raw material, so that the first raw material and the second raw material are joined. At this time, if the tension of the first raw material is maintained as is, the lithium metal (110) may be damaged by the movement of the cutting part (231). According to one specific example of the present invention, the tension of the first raw material decreases by 10% to 20%, 12.5% ​​to 20%, and 15% to 20% when in contact with the cutter (231) compared to when in motion. By reducing the tension of the first raw material when in contact with the cutter (231), damage to the lithium metal (110) of the first raw material can be minimized, and thereafter, when separated from the cutter (231), the tension can be increased again, so that the first raw material can be more easily separated from the second raw material.

[0100] A roll processing device (200) according to one embodiment of the present invention may further include components such as an encoder and an EPC in addition to a dancer roll in a running roll. The encoder serves to convert a signal into information. The EPC (Edge Position Controller) serves to determine the center of the raw material while the roll is running. According to one embodiment of the present invention, the roll processing device (200) includes a sensor that checks whether the first raw material and the second raw material are well separated in the recovery step after cutting. After cutting, when the cutting unit (231) returns to the original position, if the first raw material is not well separated from the second raw material, continuous damage to lithium metal may occur in the future process. Therefore, it is necessary to check whether the first raw material is well separated from the second raw material through the sensor. If the first raw material is not well separated from the second raw material, measures such as stopping the device to separate the first raw material or momentarily increasing the tension of the first and second raw materials to separate them can be taken.

[0101] In a method for processing lithium metal according to one specific embodiment of the present invention, a lithium metal (110) is cut in a cutting step to form a negative electrode tab (110T). The negative electrode tabs (110T) are positioned side by side in the thickness direction as shown in FIG. 1. The negative electrode tabs (110T) positioned side by side in the thickness direction can be subsequently bonded and connected to a lead. In the cutting step, the lithium metal (110) is cut to form a chamfer (110C) together with the negative electrode tab (110T). The chamfer (110C) can then serve as a reference for dividing each layer in the electrode assembly (100).

[0102] According to one specific example of the present invention, a pair of adjacent tabs (110T) with respect to the chamfer (110C) are spaced at the same distance from the chamfer. This means that a pair of adjacent tabs (110T) with respect to the chamfer (110C) are positioned at symmetrical distances. By positioning the tabs (110T) in this manner, when folding with respect to the chamfer (110C) for the purpose of manufacturing the electrode assembly (100), the tabs (110T) of each layer can be positioned side by side in the thickness direction.

[0103] According to one specific example of the present invention, the tab (110T) is positioned closer to one of a pair of adjacent chamfers (110C) based on the tab. This means that a pair of adjacent chamfers (110C) based on the tab are positioned at a non-symmetrical distance. As shown in FIG. 1, when the negative electrode tab (110C) is not positioned at the center of each layer but is offset to one side, the lithium metal (110) of the negative electrode may have a structure as shown in FIGS. 2 and 3 when unfolded. When the negative electrode tab (110C) is formed in this form, it may be a structure advantageous for positioning the positive electrode tab in the same direction. However, when processing the lithium metal (110) to extend in the longitudinal direction as in one specific example of the present invention, such an asymmetrical structure requires special attention.

[0104] According to one specific example of the present invention, when processing lithium metal and cutting based on one layer in the electrode assembly, it is impossible to manufacture a negative electrode tab (110T) that is biased to one side in one layer. This is because, when manufacturing the electrode assembly, the lithium metal is folded rather than cut for each layer. Therefore, it may be desirable to cut at least two layers at once. According to one specific example of the present invention, when the area divided by four chamfers (110C) is viewed as one unit area, the cutter (230) cuts two or more unit areas at once. The unit area may mean one layer to be applied to the electrode assembly. Since the processed lithium metal (110) as in FIG. 2 has a structure that is repeated every two unit areas, the cutting blade (231K) may be configured as in FIG. 7. In the case of having a cutting blade (231K) as in Fig. 7, a tab (110T) can be formed by cutting by running the roll in two unit areas.

[0105] When the tab (110T) in each layer has an asymmetrical structure, the lithium metal (110) applied to the tab-less wrapping portion can be processed even through the cutting blade (231K) forming the tab. According to one specific example of the present invention, the tab-less unit region is manufactured by moving only one unit region after cutting and performing overlapping cuts. As described above, when the cutting blade (231K) as in FIG. 7 is provided, the tab (110T) can be formed by driving the roll and cutting two unit regions at a time. However, in contrast, when the roll is driven by moving one unit region at a time, two cuts are overlapped in the unit region. Since the two cuts are cut to form tabs at different positions, the tab formed by the first cut is removed by the second cut. At this time, in order to perfectly cut the tab, it is preferable that the tab be offset to one side of the unit region so that the tab does not pass through the center of the unit region. Since the chamfer (110C) is formed through cutting, if the unit area is not driven as a unit, the chamfer (110C) may be formed in an unnecessary location, which may be undesirable.

[0106]

[0107] Although the specific examples described above have been limited to specific examples and drawings, those skilled in the art will recognize that various modifications and variations can be made based on the above teachings. For example, appropriate results can still be achieved even if the described techniques are performed in a different order than described, and / or components of the described systems, structures, devices, circuits, etc. are combined or combined in a different manner than described, or are replaced or substituted with other components or equivalents.

[0108] [Explanation of symbols]

[0109] 100: (Stack-folding) electrode assembly

[0110] 110: Lithium metal (cathode)

[0111] 110T: Lithium metal tab (negative tab)

[0112] 111: First protective layer

[0113] 112: Second protective layer

[0114] 120: Membrane

[0115] 130: Bipolar

[0116] 200: Lithium metal processing device

[0117] 210: First roll set

[0118] 211: Winder (for supplying and recovering the first raw material)

[0119] 212: (First raw material) driving roll

[0120] 213: Alignment roll (of the first raw material)

[0121] 220: Second roll set

[0122] 221: Winder (for supplying and recovering secondary raw materials)

[0123] 222: (second raw material) driving roll

[0124] 223: Alignment roll (of the second raw material)

[0125] 230: Cutter

[0126] 231: (Cutting part of cutter)

[0127] 231K: (Cutting edge) cutting edge

[0128] 231F: Buffer (at the cut)

[0129] 232: (Cutter's) support

[0130] a1: First angle of the cutting blade

[0131] a2: Second angle of the cutting blade

Claims

1. A supply step of separating a first raw material composed of lithium metal having a first protective layer bonded to one side and a second raw material composed of a second protective layer, and supplying the raw materials so that the lithium metal is positioned between the first protective layer and the second protective layer; A cutting step of cutting lithium metal by applying pressure to the supplied raw material through a cutter on the first protective layer and the second protective layer; and A method for processing lithium metal for an anode of an electrode assembly, comprising: a recovery step of recovering raw materials by separating the first raw material and the second raw material after cutting; 2. In claim 1, The above first raw material is supplied and recovered by the first roll set, The above second raw material is supplied and recovered by the second roll set, A method for processing lithium metal for an anode of an electrode assembly, characterized in that each of the first roll set and the second roll set comprises a plurality of rolls capable of moving raw materials.

3. In claim 1, A method for processing lithium metal for an anode of an electrode assembly, characterized in that the first protective layer and the second protective layer are polymer protective films made of different materials.

4. In claim 3, A method for processing lithium metal for a negative electrode of an electrode assembly, characterized in that the first protective layer is a polyolefin-based polymer protective film.

5. In claim 4, A method for processing lithium metal for a negative electrode of an electrode assembly, characterized in that the second protective layer is a polyester-based polymer protective film.

6. In claim 1, A method for processing lithium metal for a negative electrode of an electrode assembly, characterized in that in the above cutting step, the first raw material and the second raw material are positioned apart from each other before being pressurized by a cutting machine.

7. In claim 6, The above cutter is composed of a cutting part and a supporting part, A method for processing lithium metal for a negative electrode of an electrode assembly, characterized in that the cutting portion and the supporting portion are located on opposite sides with respect to the lithium metal.

8. In claim 7, The above cutting portion includes a protruding cutting blade, A method for processing lithium metal for an anode of an electrode assembly, characterized in that the cutting part moves toward the support part to pressurize the raw material and cut the lithium metal.

9. In claim 8, A method for processing lithium metal for an anode of an electrode assembly, characterized in that the internal space between the protruding cutting blades and the cutting blades in the above-mentioned cutting section is filled with a buffer material.

10. In claim 7, A method for processing lithium metal for a negative electrode of an electrode assembly, characterized in that the lithium metal is cut by the pressure of a protruding cutting blade and ultrasonic waves.

11. In claim 2, Each of the first roll set and the second roll set includes a dancer roll capable of controlling the tension of the raw material running on the roll, A method for processing lithium metal for an anode of an electrode assembly, characterized in that the first raw material running in the first roll set and the second raw material running in the second roll set have different tensions by the dancer rolls.

12. In claim 11, A method for processing lithium metal for a negative electrode of an electrode assembly, characterized in that the first raw material running in the first roll set has a tension of 20 N / m to 40 N / m.

13. In claim 11, A method for processing lithium metal for a negative electrode of an electrode assembly, characterized in that the second raw material running in the second roll set has a tension of 40 N / m to 60 N / m.

14. In claim 11, A method for processing lithium metal for a negative electrode of an electrode assembly, characterized in that the tension of the first raw material is reduced by 10% to 20% when in contact with a cutter compared to when running.

15. In claim 1, A method for processing lithium metal for an anode of an electrode assembly, characterized in that the above cutting step cuts the lithium metal to form a tab.

16. In claim 15, A method for processing lithium metal for an anode of an electrode assembly, characterized in that the above cutting step cuts the lithium metal to form tabs and chamfers.

17. In claim 16, A method for processing lithium metal for a negative electrode of an electrode assembly, characterized in that a pair of adjacent tabs are spaced apart from the chamfer by the same distance.

18. In claim 17, A method for processing lithium metal for a negative electrode of an electrode assembly, characterized in that the tab is positioned closer to one of a pair of adjacent chamfers with respect to the tab.

19. In claim 16, A method for processing lithium metal for an anode of an electrode assembly, characterized in that when an area divided by four chamfers is viewed as one unit area, the cutting machine cuts two or more unit areas at a time.

20. In claim 19, Through the above cutting step, a unit area without a tab is manufactured, A method for processing lithium metal for an anode of an electrode assembly, characterized in that the unit area without the tab is manufactured by moving only one unit area after cutting and then cutting repeatedly.

21. In claim 1, A method for processing lithium metal for an anode of an electrode assembly, characterized in that in the above recovery step, the cut lithium metal pieces of the first raw material are removed.

22. In claim 21, A method for processing lithium metal for an anode of an electrode assembly, characterized in that the first raw material from which lithium metal pieces have been removed in the above recovery step is recovered by separating it into processed lithium metal and a first protective layer.

23. In claim 8, A method for processing lithium metal for a negative electrode of an electrode assembly, characterized in that the cutting blade has an asymmetrical shape on both sides with respect to the tip of the cutting blade as a standard.

24. In claim 1, A method for processing lithium metal for a negative electrode of an electrode assembly, characterized in that the process of separating the first raw material and the second raw material in the above recovery step is checked through a sensor.

25. In claim 10, A method for processing lithium metal for a negative electrode of an electrode assembly, characterized in that when the lithium metal and the second protective layer come into contact, the cutting blade generates ultrasonic waves.

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