Negative electrode, negative electrode sheet, and electrode assembly

Abstract

The present invention provides a negative electrode, a negative electrode sheet, and an electrode assembly that enable efficient processing by performing a non-contact notching process, do not generate lithium dust, and can improve the complex problems that may arise from lithium metal during future bonding processes with leads. The negative electrode according to various embodiments includes a first metal layer formed of lithium metal and a second metal layer formed of a material other than lithium metal, which is at least partially overlapped and bonded to the first metal layer, wherein the second metal layer may be interposed between a plurality of first metal layers, or the first metal layer may be interposed between a plurality of second metal layers. Other embodiments are also possible.

Description

TECHNICAL FIELD

[0001] Mutual citation with related applications

[0002] This application claims priority based on Korean Patent Application Nos. 10-2024-0065416, 10-2024-0094209, and 10-2025-0065353, filed with the Korean Intellectual Property Office on May 20, 2024, July 17, 2024, and May 20, 2025, respectively, the entire contents of which are incorporated herein by reference.

[0003] Technical field

[0004] The present application relates to a negative electrode, a negative electrode sheet, and an electrode assembly. BACKGROUND ART

[0005] In recent years, demand for mobile devices such as smartphones, tablet PCs, and wireless earphones has been increasing. In addition, as the development of electric vehicles, energy storage batteries, robots, and satellites is fully underway, research on high-performance secondary batteries capable of repeated charging and discharging as an energy source is being actively conducted.

[0006] Secondary batteries currently commercialized include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium secondary batteries. Among these, lithium secondary batteries have advantages such as almost no memory effect compared to nickel-based secondary batteries, allowing free charging and discharging, a very low self-discharge rate, and high energy density. SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] On the other hand, lithium metal batteries sometimes use lithium metal as the anode. While lithium metal is advantageous for increasing the energy density of batteries, it is more brittle and prone to burning than copper (Cu), which was previously the main material used, making it difficult to handle in some cases.

[0008] Furthermore, in order to prevent the lithium metal from burning off during the notching process that forms the tab on the negative electrode, the release film is sometimes applied in layers while the material is being punched with a puncher. However, this is uneconomical as the release film is consumed, the process speed slows down due to the deceleration of the puncher, and there is a potential problem that the remaining scrap after punching must be processed separately.

[0009] Furthermore, if a non-contact method (e.g., laser use) is applied during the notching process instead of a contact method such as a notching device, there is a possibility that lithium dust (hume) may be generated due to the direct application of energy to the lithium metal, which could lead to safety problems.

[0010] Various embodiments of this application enable efficient processes by performing a non-contact notching process, do not generate lithium dust, and can provide a negative electrode, negative electrode sheet, and electrode assembly that can improve the complex problems that may arise from lithium metal during future bonding processes with leads. [Means for solving the problem]

[0011] An anode according to one embodiment of this application includes a first metal layer formed of lithium metal and a plurality of second metal layers formed of a material other than lithium metal, which overlap and bond with a portion of the first metal layer, and the first metal layer may be interposed between the plurality of second metal layers.

[0012] In a negative electrode according to one embodiment of this application, the plurality of second metal layers may be formed of a metal material that is less reactive than lithium metal.

[0013] In a negative electrode according to one embodiment of the present application, each of a plurality of second metal layers includes a first region overlapping with the first metal layer and a second region other than the first region, and at least one of the plurality of second metal layers may be formed such that the length in the width direction of the first region is shorter than the length in the width direction of the second region.

[0014] In a negative electrode according to one embodiment of this application, at least one first region of a plurality of second metal layers can be embedded in the first metal layer.

[0015] In a negative electrode according to one embodiment of this application, the first regions of each of the multiple second metal layers can have substantially the same widthwise length from one another.

[0016] In a negative electrode according to one embodiment of this application, a negative electrode tab can be included in at least one second region of a plurality of second metal layers.

[0017] In a negative electrode according to one embodiment of this application, at least one second region among a plurality of second metal layers may include a margin region which is a region other than the region corresponding to the negative electrode tab.

[0018] An anode according to one embodiment of this application may include a plurality of first metal layers formed of lithium metal, a second metal layer formed of a material other than lithium metal, which includes a first region overlapping with at least one of the plurality of first metal layers and a second region other than the first region, interposed between the plurality of first metal layers and bonded to the plurality of first metal layers, and a margin region provided adjacent to at least one of the plurality of first metal layers in the second region.

[0019] In the negative electrode according to one embodiment of this application, the second metal layer may be formed of a metal material that is less reactive than lithium metal.

[0020] A negative electrode according to one embodiment of this application may further include a negative electrode tab formed in a second region.

[0021] In a negative electrode according to one embodiment of this application, when viewed from the thickness direction of one of the first metal layers, at least a portion of the margin region may be provided between the negative electrode tab and one of the first metal layers, or between the negative electrode tab and the first region.

[0022] In a negative electrode according to one embodiment of this application, at least a portion of the first region of the second metal layer may include one or more of a predetermined pattern structure and a surface-treated region.

[0023] In a negative electrode according to one embodiment of this application, the length in the width direction of the first region of the second metal layer may be formed to be shorter than the length in the width direction of the second region.

[0024] A negative electrode sheet according to one embodiment of this application includes a first metal layer and a second metal layer that overlaps and is bonded to a portion of one side edge of the first metal layer, the second metal layer includes a first region that overlaps with the first metal layer and a second region which is the region other than the first region, a negative electrode tab including a first tab, a second tab and a third tab is formed in the second region, the second and third tabs which are mutually adjacent on both sides with respect to the first tab are each located at a predetermined distance from the first tab, and the first length which is the distance between the first tab and the second tab may be formed to be longer than the second length which is the distance between the first tab and the third tab.

[0025] In a negative electrode sheet according to one embodiment of this application, the second metal layer may be formed of a metal material that is less reactive than the first metal layer.

[0026] An electrode assembly according to one embodiment of this application includes a positive electrode, a negative electrode, and a separator membrane, wherein the negative electrode includes a first metal layer made of lithium metal and a second metal layer that overlaps and is bonded to a portion of one side edge of the first metal layer, the second metal layer being made of a metal material less reactive than lithium metal, the negative electrode is interposed between two separator membranes to form a negative electrode structure, the negative electrode structure includes a stack portion and a folding portion, and the electrode assembly may have a structure in which the stack portion and the positive electrode are alternately and sequentially stacked.

[0027] In an electrode assembly according to one embodiment of this application, the stacking portion and the folding portion may each be provided in multiple units.

[0028] In an electrode assembly according to one embodiment of this application, the negative electrode includes a plurality of second metal layers, and the first metal layer may be interposed between the plurality of second metal layers.

[0029] In an electrode assembly according to one embodiment of this application, the negative electrode includes a plurality of first metal layers, and a second metal layer may be interposed between the plurality of first metal layers.

[0030] In an electrode assembly according to one embodiment of this application, the positive electrode includes a positive electrode active material layer containing a positive electrode active material and a positive electrode current collector supporting the positive electrode active material layer, wherein the positive electrode active material may contain a sulfur compound. [Effects of the Invention]

[0031] According to various embodiments of this disclosure, it is possible to provide a negative electrode, negative electrode sheet, or electrode assembly that maximizes energy density while minimizing the occurrence of defects that may occur in the manufacturing process of a battery using lithium metal as the main material for the negative electrode. For example, an efficient process can be achieved by performing a non-contact notching process, which does not generate lithium dust and can improve the complex problems caused by lithium metal in the process of joining it with leads in the future.

[0032] The drawings shown in this application are of embodiments of this application, and the proportions of width, width, or thickness (or height) of each component are for illustrative purposes only and may differ from actual proportions. In addition, in the coordinate system shown in the drawings, each axis may be perpendicular to the others, the direction indicated by the arrow may be the + direction, and the direction directly opposite to the direction indicated by the arrow (rotated 180 degrees) may be the - direction. [Brief explanation of the drawing]

[0033] [Figure 1]This is a plan view illustrating at least a portion of the negative electrode according to one embodiment of this application. [Figure 2] This figure illustrates a part of the manufacturing process of the negative electrode sheet according to the first embodiment of this application. [Figure 3] This figure illustrates a part of the manufacturing process of the negative electrode sheet according to the first embodiment of this application. [Figure 4] This figure illustrates a part of the manufacturing process of the negative electrode sheet according to the second embodiment of this application. [Figure 5] This figure illustrates a part of the manufacturing process of the negative electrode sheet according to the second embodiment of this application. [Figure 6] This figure illustrates a part of the manufacturing process of the negative electrode sheet according to the second embodiment of this application. [Figure 7] This figure illustrates a part of the manufacturing process of the negative electrode sheet according to the third embodiment of this application. [Figure 8] This figure illustrates a part of the manufacturing process of a negative electrode sheet according to one embodiment of this application. [Figure 9] Figure 8 is a plan view illustrating a part of the manufacturing process of a negative electrode sheet according to one embodiment of this application. [Figure 10] This is a plan view illustrating at least a portion of the negative electrode sheet according to one embodiment of this application. [Figure 11] This is a plan view illustrating, in one embodiment of the present application, how a negative electrode sheet is cut to form a negative electrode. [Figure 12] This is a plan view illustrating at least a portion of the negative electrode according to one embodiment of this application. [Figure 13] This figure illustrates a part of the manufacturing process of the negative electrode sheet according to the fourth embodiment of this application. [Figure 14] This figure illustrates a part of the manufacturing process of the negative electrode sheet according to the fourth embodiment of this application. [Figure 15] This figure illustrates a part of the manufacturing process of the negative electrode sheet according to the fifth embodiment of this application. [Figure 16]This figure illustrates a part of the manufacturing process of the negative electrode sheet according to the fifth embodiment of this application. [Figure 17] This figure illustrates a part of the manufacturing process of the negative electrode sheet according to the fifth embodiment of this application. [Figure 18] This figure illustrates a part of the manufacturing process of the negative electrode sheet according to the sixth embodiment of this application. [Figure 19] This figure illustrates a part of the manufacturing process of a negative electrode sheet according to one embodiment of this application. [Figure 20] This figure illustrates a part of the manufacturing process of a negative electrode sheet according to one embodiment of this application. [Figure 21] Figure 20 is a plan view illustrating a part of the manufacturing process of a negative electrode sheet according to one embodiment of this application. [Figure 22] This is a plan view illustrating at least a portion of the negative electrode sheet according to one embodiment of this application. [Figure 23] This is a plan view illustrating, in one embodiment of the present application, how a negative electrode sheet is cut to form a negative electrode. [Figure 24] This is a plan view illustrating at least a portion of the negative electrode according to one embodiment of this application. [Figure 25] This figure illustrates a part of the manufacturing process of the negative electrode sheet according to the seventh embodiment of this application. [Figure 26] This figure illustrates a part of the manufacturing process of the negative electrode sheet according to the seventh embodiment of this application. [Figure 27] This figure illustrates a part of the manufacturing process of the negative electrode sheet according to the eighth embodiment of this application. [Figure 28] This figure illustrates a part of the manufacturing process of the negative electrode sheet according to the eighth embodiment of this application. [Figure 29] This figure illustrates a part of the manufacturing process of the negative electrode sheet according to the eighth embodiment of this application. [Figure 30] This figure illustrates a part of the manufacturing process of the negative electrode sheet according to the ninth embodiment of this application. [Figure 31]This figure illustrates a part of the manufacturing process of a negative electrode sheet according to one embodiment of this application. [Figure 32] This figure illustrates a part of the manufacturing process of a negative electrode sheet according to one embodiment of this application. [Figure 33] Figure 32 is a plan view illustrating a part of the manufacturing process of a negative electrode sheet according to one embodiment of this application. [Figure 34] This is a plan view illustrating at least a portion of the negative electrode sheet according to one embodiment of this application. [Figure 35] This is a plan view illustrating, in one embodiment of the present application, how a negative electrode sheet is cut to form a negative electrode. [Figure 36] This is a plan view illustrating at least a portion of an electrode assembly according to one embodiment of this application. [Modes for carrying out the invention]

[0034] Prior to a detailed description of the present invention, terms and words used herein and in the claims may not be construed to be limited to their ordinary or dictionary meanings. Furthermore, the inventors should interpret them in a sense and concept consistent with the technical idea of ​​this application, based on the principle that terms can be appropriately defined in terms of concepts in order to best describe their invention. The embodiments described herein and configurations shown in the drawings are merely the most preferred embodiments of this application and may not represent all of the technical idea of ​​this application. Accordingly, at the time of filing of this application, there may be a variety of equivalents and variations that can substitute for them.

[0035] The same reference numerals or symbols in the drawings attached to this specification may indicate parts or components that perform substantially the same function. For convenience of explanation and understanding, different embodiments may also be described using the same reference numerals or symbols. That is, even if components with the same reference numerals are illustrated in multiple drawings, not all of the drawings may represent a single embodiment.

[0036] In the following description, singular expressions include plural expressions unless the context clearly indicates otherwise. Terms such as “contains” or “constitutes” are intended to specify the existence of features, figures, stages, operations, components, parts, or combinations thereof described in the specification, and should not be understood as preemptively excluding the existence or possibility of adding one or more different features, figures, stages, operations, components, parts, or combinations thereof.

[0037] Furthermore, in the following explanation, terms such as top, upper, lower, lower, side, front, and rear are used based on the direction shown in the drawing, and may be expressed differently if the direction of the object changes.

[0038] Furthermore, within this specification and the claims, terms containing an ordinal number after a dash, such as "1-1" and "1-2," may be used to distinguish between components. Such ordinal numbers may be used to distinguish identical or similar components from one another, and the use of such ordinal numbers should not restrict the meaning of the terms. For example, components combined with such ordinal numbers should not be restricted in terms of their order of use or arrangement by the number.

[0039] In this specification, "battery" may be used interchangeably with "cell." Furthermore, "battery" or "cell" may be a general term referring to these units, namely a battery cell, a battery module containing a battery cell, or a battery pack.

[0040] This application provides at least one of a negative electrode, a negative electrode sheet, and an electrode assembly that enables an efficient process by performing a non-contact notching process, does not generate lithium dust, and can improve the complex problems that arise from lithium metal during the subsequent bonding process with leads.

[0041] Figure 1 is a plan view illustrating at least a portion of the negative electrode 10 according to one embodiment of this application.

[0042] In one embodiment, the negative electrode 10 may include a first metal layer 100 and a second metal layer 200.

[0043] In one embodiment of the negative electrode 10, the second metal layer 200 can be formed by overlapping and bonding with a portion of the first metal layer 100.

[0044] For example, the second metal layer 200 may protrude in one direction from one side edge of the first metal layer 100.

[0045] Furthermore, for example, in the negative electrode 10, the second metal layer 200 may overlap and bond with a portion of one side edge of the first metal layer 100.

[0046] In one embodiment of the negative electrode 10, the second metal layer 200 may be formed of a metal material that is less reactive than the first metal layer 100.

[0047] For example, the first metal layer 100 may be formed of lithium metal (Li metal). The second metal layer 200 may be formed of a material other than lithium metal.

[0048] For example, the second metal layer 200 may be formed from another metal that is less reactive than lithium (Li) metal.

[0049] For example, the second metal layer 200 may be formed from at least one of the following materials: copper (Cu), nickel (Ni), or stainless steel.

[0050] In one embodiment, the second metal layer 200 can have a variety of structures. The second metal layer 200 may include one or more of a predetermined pattern structure and a surface-treated region. One or more of the predetermined pattern structure and the surface-treated region may be included in at least a portion of the first region 210.

[0051] For example, at least a portion of the second metal layer 200 (for example, at least a portion of the portion in contact with the first metal layer 100) may include a predetermined pattern structure. The pattern structure may be, for example, a mesh structure or a structure in which a grid pattern is formed on the surface, and all of these structures may be present. For example, a mesh structure may mean a structure in which a plurality of holes are formed, and a grid pattern may mean a structure in which a plurality of grooves are formed. Through this, the contact area between the first metal layer 100 and the second metal layer 200 can be maximized, thereby improving the bonding strength.

[0052] Furthermore, at least a portion of the second metal layer 200 (for example, at least a portion of the area of ​​the second metal layer 200 that is in contact with the first metal layer 100) may be surface-treated. Surface treatment can be carried out, for example, by plasma treatment. If surface-treated, it can have a different surface roughness than other areas. Through such appropriate surface treatment, the bonding strength between the first metal layer 100 and the second metal layer 200 can be improved. In this specification, reactivity can mean the property of oxidizing to become a cation, and low reactivity can mean a relatively low tendency to become a cation.

[0053] On the other hand, in the negative electrode 10 according to one embodiment, the second metal layer 200 may be formed of a metal material that does not easily react with the first metal layer 100 upon contact.

[0054] For example, the second metal layer 200 may not contain aluminum (Al), which can undergo an alloying reaction with lithium metal. In this specification, "not containing a particular substance" means "substantially not containing," which preferably means 0% by weight, but can also mean containing 1% or less by weight, 0.5% or less by weight, or 0.1% or less by weight relative to the total weight.

[0055] In one embodiment of the negative electrode 10, the second metal layer 200 may include a first region 210 (e.g., overlapping region) that overlaps with the first metal layer 100 and a second region 220 (e.g., non-overlapping region) that is a region other than the first region 210. For example, with respect to the thickness direction of the first metal layer 100 (e.g., the +Z axis direction in Figure 1), the second metal layer 200 may include a first region 210 (e.g., overlapping region) that overlaps with the first metal layer 100 and a second region 220 (e.g., non-overlapping region) that is a region other than the first region 210 (i.e., a region that does not overlap with the first metal layer 100).

[0056] In other words, unless otherwise specified in this specification, the first region 210 of the second metal layer 200 may mean an overlapping region where multiple components overlap, and the second region 220 of the second metal layer 200 may mean a non-overlapping region other than the first region 210.

[0057] In this specification, the thickness of the first metal layer 100 is not particularly limited, but in order to be free-standing, it may be, for example, 10 μm to 200 μm, 15 μm to 180 μm, 20 μm to 150 μm, 25 μm to 130 μm, 30 μm to 100 μm, 35 μm to 80 μm, or 40 μm to 60 μm. Also in this specification, the thickness of the second metal layer 200 is not particularly limited, but in order to improve energy density, it may be, for example, 5 μm to 20 μm, 6 μm to 18 μm, 7 μm to 16 μm, 8 μm to 14 μm, or 9 μm to 12 μm, or 10 μm or less. In this specification, unless otherwise defined, thickness may mean the length in the thickness direction as described above (e.g., the +Z axis direction in Figure 1).

[0058] In one example, the thickness of the first metal layer 100 may be greater than the thickness of the second metal layer 200. This can improve the tensile strength of the negative electrode 10.

[0059] In one embodiment, the length W1 of the first region 210 in a first direction (e.g., the width direction) (e.g., the +Y axis direction in Figure 1) may be shorter than the length W2 of the second region 220 in a first direction (e.g., the width direction).

[0060] For example, if the widthwise length W1 of the first region 210 is excessively short, it may be difficult to ensure the bonding stability between the first metal layer 100 and the second metal layer 200. Conversely, if it is excessively long, unnecessary manufacturing costs may be incurred, potentially lowering the energy density of the battery. As a result, the widthwise length W1 of the first region 210 in one embodiment may be approximately 0.5 mm to 20 mm.

[0061] For example, the widthwise length W2 of the second region 220 may be longer than the minimum required length (e.g., about 8 mm) of the negative electrode tab (e.g., see 230 in Figure 10) for joining with the negative electrode lead. Thus, in the negative electrode 10 according to one embodiment, if the widthwise length W2 of the second region 220 is formed to be longer than the minimum required length of the negative electrode tab, damage to the first metal layer 100 can be prevented by performing the process for forming the negative electrode tab only in the second region 220 and not performing a separate process for forming the negative electrode tab in the first region 210.

[0062] In the negative electrode 10 according to one embodiment, the ratio W2 / W1 of the length W2 in the width direction of the second region 220 to the length W1 in the width direction of the first region 210 may be greater than 1 and less than or equal to 20.

[0063] In the negative electrode 10 according to another embodiment, the ratio W2 / W1 of the widthwise length W2 of the second region 220 to the widthwise length W1 of the first region 210 may be between 2 and 18.

[0064] Furthermore, in the negative electrode 10 according to another embodiment, the ratio W2 / W1 of the widthwise length W2 of the second region 220 to the widthwise length W1 of the first region 210 may be 5 or more and 16 or less.

[0065] In the negative electrode 10 according to various embodiments of this disclosure, the ratio W2 / W1 of the widthwise length W2 of the second region 220 to the widthwise length W1 of the first region 210 satisfies a predetermined range, thereby maximizing the capacity while minimizing the size of the negative electrode 10.

[0066] In the negative electrode 10 according to one embodiment, the length W1 of the first region 210 in the width direction and the length W of the entire second metal layer 200 in the width direction T the ratio W1 / W T may be 0.01 to 0.1.

[0067] In the negative electrode 10 according to one embodiment, the length W1 of the first region 210 in the width direction and the length W of the entire second metal layer 200 in the width direction T the ratio W1 / W T may be 0.02 to 0.09.

[0068] In the negative electrode 10 according to one embodiment, the length W1 of the first region 210 in the width direction and the length W of the entire second metal layer 200 in the width direction T the ratio W1 / W T may be 0.03 to 0.08.

[0069] In the negative electrode 10 according to one embodiment, the length W1 of the first region 210 in the width direction and the length W of the entire second metal layer 200 in the width direction T the ratio W1 / W T may be 0.04 to 0.07.

[0070] In various embodiments of the present disclosure, the length W1 of the first region 210 in the width direction and the length W of the entire second metal layer 200 in the width direction T the ratio W1 / W T can ensure sufficient bonding strength between the first metal layer 100 and the second metal layer 200 by satisfying a condition within a certain range.

[0071] In the negative electrode 10 according to one embodiment, the first region 210 of the second metal layer 200 may be embedded in the first metal layer 100.

[0072] For example, the first surface (e.g., top surface) of the second metal layer 200 and the first surface (e.g., top surface) of the first metal layer 100 may be formed to be located substantially on the same plane.

[0073] For example, the second metal layer 200 may have a first region 210 embedded in the first metal layer 100, and may not have an upper step between the second metal layer 200 and the first metal layer 100.

[0074] Through this configuration, even when the first metal layer 100 and the second metal layer 200 are rewinded after being joined, it is possible to effectively prevent not only the problem of meandering movement, where the alignment between the two metal layers 100 and 200 becomes misaligned, but also the problem of the electrodes twisting due to meandering.

[0075] Furthermore, when unwinding is performed after rewinding as described above to manufacture the negative electrode structure described later (e.g., see 10A in Figure 36), the problem of the first metal layer 100 and the second metal layer 200 becoming meandering can be prevented.

[0076] Furthermore, through this configuration, if there is a step between the upper surface of the first metal layer 100 and the second metal layer 200 (especially if it is thicker than the thickness of the positive electrode (see 30 in Figure 36), as described later), it is possible to prevent the stack portion 10A_S of the negative electrode structure (e.g., see negative electrode structure 10A in Figure 36) from protruding excessively, thereby preventing a decrease in the energy density per unit volume of the battery cell.

[0077] In one embodiment of the negative electrode 10, a negative electrode tab (see 230 in Figure 10) may be formed in the second region 220 of the second metal layer 200. For example, a negative electrode tab (see 230 in Figure 10) can be formed by performing a notching process on the second region 220 of the second metal layer 200. That is, the negative electrode 10 may include a negative electrode tab (see 230 in Figure 10) formed in the second region 220 of the second metal layer 200.

[0078] In one embodiment of the negative electrode 10, a plurality of negative electrode tabs (see 230 in Figure 10) may be formed. Here, the notching process is not particularly limited, but can be performed by a contact method such as a notching device or a non-contact method utilizing a laser. The negative electrode 10 may include a plurality of negative electrode tabs (230 in Figure 10) formed in the second region 220 of the second metal layer 200.

[0079] In various embodiments, the second metal layer 200 is formed of a metal material that is relatively less reactive than lithium metal, so that even if the notching process is performed in a non-contact manner, the occurrence of safety problems due to dust can be minimized.

[0080] On the other hand, the negative electrode 10 in the various embodiments of this disclosure may mean a negative electrode sheet used to manufacture multiple electrode assemblies (e.g., the negative electrode sheet 10S in Figure 10), or a form obtained by cutting a negative electrode sheet to a certain size, i.e., a portion of a negative electrode sheet, used to manufacture one electrode assembly or one battery cell.

[0081] Figures 2 and 3 illustrate a part of the manufacturing process of the negative electrode sheet (see 10S in Figure 10) according to the first embodiment of this application.

[0082] On the other hand, the manufacturing process for the negative electrode sheet (see 10S in Figure 10) can be carried out in a roll-to-roll manner, at least in part. The roll-to-roll method may be one of a continuous process in which a sheet material is processed to have a new function by applying tension to it with rolls (e.g., unwinding rolls and rewinding rolls). Because the roll-to-roll method processes the material continuously, it may be advantageous for mass production. The description of the negative electrode 10 described herein may be referenced to the description of the negative electrode sheet (see 10S in Figure 10), unless otherwise consistent.

[0083] In one embodiment, the first metal layer 100 may be in sheet form and can be transported in a specific direction via a transport roll (not shown). For example, referring to Figure 2, the first metal layer 100 can be transported in the +X direction.

[0084] Unless otherwise specified herein, the direction parallel to the direction in which the first metal layer 100 is transported may be referred to as the machine direction (MD). For example, in Figure 2, the machine direction of the first metal layer 100 may be the +X direction (or the -X direction). Also, unless otherwise specified herein, the direction perpendicular to the machine direction MD on a plane parallel to the first metal layer 100 may be referred to as the transverse direction (TD). For example, in Figure 2, the transverse direction of the first metal layer 100 may mean the +Y direction (or the -Y direction).

[0085] In one embodiment, the second metal layer 200 may be in sheet form. For example, the second metal layer 200 may be transported in the same direction as the first metal layer 100 (i.e., the machine direction) via a transport roll (not shown) while remaining positioned on the first metal layer 100 so as to overlap a portion of one side edge of the first metal layer 100. For example, referring to Figure 2, the second metal layer 200 may be transported in the +X direction, similar to the direction in which the first metal layer 100 is transported.

[0086] A method for manufacturing a negative electrode sheet according to one embodiment (see 10S in Figure 10) may include providing a first metal layer 100 and a second metal layer 200. One or more of the first metal layer 100 and the second metal layer 200 may be provided by the roll-to-roll method described above.

[0087] In one embodiment, referring to Figure 3, the first metal layer 100 and the second metal layer 200 can be rolled simultaneously by a roller R. Specifically, the roller R can apply pressure to the overlapping region of the first metal layer 100 and the second metal layer 200 to join them together. The roller R is positioned in the thickness direction (e.g., the +Z axis direction) of the overlapping portion of the first metal layer 100 and the second metal layer 200, and can pressurize the first metal layer 100 and the second metal layer 200 simultaneously. On the other hand, unless otherwise specifically limited herein, the thickness direction may be perpendicular to either the machine direction MD or the vertical direction TD.

[0088] Figures 4 to 6 illustrate a part of the manufacturing process of the negative electrode sheet (see 10S in Figure 10) according to the second embodiment of this application.

[0089] Referring to Figure 4, in a method for manufacturing a negative electrode sheet according to one embodiment, the roller R can roll a portion of one side edge of the first metal layer 100 as it is transported in the +X axis direction. In this case, unlike the method described with reference to Figure 3, the object rolled by the roller R may be the first metal layer 100 before it overlaps with the second metal layer 200.

[0090] Referring to Figure 5, a groove H can be formed in the first metal layer 100 by the pressure of the roller R, and the second metal layer 200 can be positioned at a location corresponding to the formed groove H.

[0091] Referring to Figure 6, after the second metal layer 200 is placed in the groove H of the first metal layer 100, the first metal layer 100 and the second metal layer 200 can be joined together by a joining means such as a laser device LA. In Figure 6, a laser device LA is illustrated as an exemplary joining means, but other joining means are not limited to this in the various embodiments of this disclosure, and welding devices and the like may be used as joining means.

[0092] Figure 7 illustrates a part of the manufacturing process of the negative electrode sheet (see 10S in Figure 10) according to the third embodiment of this application.

[0093] Referring to Figure 7, in various embodiments of the negative electrode sheet, the first metal layer 100 and the second metal layer 200 can be joined using a binder B. For example, as shown in Figure 4, after a roller R rolls a portion of one side edge of the first metal layer 100, the binder B can be applied to the groove H formed by the rolling, and the first metal layer 100 and the second metal layer 200 can be joined by positioning the second metal layer 200 at a position corresponding to the groove H to which the binder B has been applied.

[0094] In this embodiment, the binder B may be made of a material that can have a predetermined adhesive strength without chemically reacting with one or more of the first metal layer 100 and the second metal layer 200.

[0095] Binder B includes, for example, polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-co-trichloroethylene, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate. It may contain one or more selected from the group consisting of propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, carboxyl methyl cellulose, acrylonitrile-styrene-butadiene copolymer, polyimide, and styrene-butadiene rubber (SBR).

[0096] Figure 8 illustrates a part of the manufacturing process of a negative electrode sheet 10S according to one embodiment of this application. Unless otherwise specified herein, the negative electrode sheet 10S can mean a state in which a first metal layer 100 and a second metal layer 200 are bonded together. Here, "bonded" does not simply mean a state in which the first metal layer 100 and the second metal layer 200 are in surface contact, but can mean a state in which the second metal layer 200 is attached to the first metal layer 100 by a mechanical or chemical bonding method (e.g., rolling, laser bonding, binder bonding, etc.).

[0097] Figure 9 is a plan view of Figure 8 and illustrates a part of the manufacturing process of the negative electrode sheet 10S according to one embodiment of this application.

[0098] Referring to Figure 8, in one embodiment, the first metal layer 100 and the second metal layer 200 can be joined to each other to form a joint boundary line CL.

[0099] A method for manufacturing a negative electrode sheet 10S according to one embodiment may include the steps of joining a first metal layer 100 and a second metal layer 200 to each other, and forming a joining boundary line CL by joining the first metal layer 100 and the second metal layer 200 to each other.

[0100] The joint boundary line CL may, for example, correspond to the edge of the first metal layer 100 that overlaps with the second metal layer 200. For example, the joint boundary line CL may correspond to the line of the edge of the first metal layer 100 that overlaps with the second metal layer 200, with respect to the thickness direction of the first metal layer 100 (e.g., the +Z axis direction in Figure 8).

[0101] Referring to Figures 8 and 9, a notching process can be performed on the negative electrode sheet 10S according to one embodiment using a laser device LA.

[0102] For example, the laser L generated by the laser device LA may be irradiated onto a second region 220 of the second metal layer 200, thereby partially cutting the second region 220 to form a negative electrode tab (see 230 in Figure 10).

[0103] Figure 10 is a plan view illustrating at least a portion of the negative electrode sheet 10S according to one embodiment of this application. Figure 11 is a plan view illustrating, in one embodiment of this application, how the negative electrode sheet (see 10S in Figure 10) is cut to form the negative electrode 10.

[0104] In one embodiment, the negative electrode sheet 10S may have a negative electrode tab 230 formed in the second region 220, including a first tab 231, a second tab 232, and a third tab 233. That is, the negative electrode sheet 10S according to the embodiment may include a negative electrode tab 230 formed in the second region 220.

[0105] For example, the second tab 232 and the third tab 233, which are adjacent to each other on both sides of the first tab 231, can each be positioned at a predetermined distance from the first tab 231.

[0106] For example, the first length W is the distance between the first tab 231 and the second tab 232. 12 The second length W is between the first tab 231 and the third tab 233. 13 It can be formed to be longer than this. Such a structure may be advantageous for aligning the tabs when manufacturing the negative electrode structure (see 10A in Figure 36), which includes the folding and stacking sections described later, by varying the distance between the tabs.

[0107] On the other hand, the negative electrode sheet 10S according to one embodiment may further include a margin region 235, which is a region in the second region 220 other than the region corresponding to the negative electrode tab 230. Referring to Figure 10, at least a portion of the margin region 235 may be provided between the negative electrode tab 230 and the first metal layer 100. For example, when viewed from the thickness direction of the first metal layer 100 (i.e., the +Z axis direction), at least a portion of the margin region 235 may be provided between the negative electrode tab 230 and the first metal layer 100. Also, referring to Figure 10, at least a portion of the margin region 235 may be provided between the negative electrode tab 230 and the first region 210.

[0108] For example, when viewed from the thickness direction of the first metal layer 100 (i.e., the +Z axis direction), at least a portion of the margin region 235 may be provided between the negative electrode tab 230 and the first region 210. That is, referring to Figure 10, the first region 210 may be provided between the margin region 235 and the first metal layer 100. When viewed from the thickness direction of the first metal layer 100 (i.e., the +Z axis direction), the first region 210 may be provided between the margin region 235 and the first metal layer 100. Through this, even if the manufacturing process of the negative electrode sheet 10S is carried out in a roll-to-roll manner, the stretching of the first metal layer 100, which is lithium metal, in the mechanical direction MD is suppressed, and an advantageous effect can be obtained during the continuous notching process.

[0109] In other words, the negative electrode sheet 10S according to one embodiment may include a margin region 235 which is part of the second region 220. For example, the margin region 235 may be provided adjacent to the first metal layer 100. Here, the margin region 235 may be a region in the second region 220 other than the region where the negative electrode tab 230 is formed by the notching process. Also, the negative electrode sheet 10S may be in a state where the negative electrode tab 230 has not been formed, and the negative electrode tab 230 can be formed by performing the notching process all at once while multiple negative electrode sheets 10S are stacked in one direction (for example, in the thickness direction of the first metal layer 100 (i.e., the +Z axis direction)) or folded. Through this, the process can be simplified and the tab alignment mismatch phenomenon that occurs when the negative electrode tab 230 is formed in advance can be minimized. In particular, such an effect may be highlighted in bidirectional batteries.

[0110] A bidirectional battery can mean a battery in which a positive electrode tab (not shown) connected to a positive electrode (e.g., see positive electrode 30 in Figure 36) and a negative electrode tab 230 protrude from one side of the main body of an electrode assembly (e.g., see electrode assembly 1 in Figure 36) in opposite directions. Alternatively, a bidirectional battery may be a battery in which a positive electrode lead connected to one or more positive electrode tabs and protruding from one side of the main body of an electrode assembly (e.g., see electrode assembly 1 in Figure 36), and a negative electrode lead connected to one or more negative electrode tabs 230 and protruding from one side of the main body of an electrode assembly, both oriented in opposite directions.

[0111] In one embodiment, the negative electrode sheet 10S may be cut via a cutting machine (not shown) according to predetermined rules. The predetermined rules are not limited but may, for example, be for standardizing the negative electrodes 10 to be formed, as can be seen in Figure 11. The cutting machine may, but is not limited to, one or more of the following: blade contact and laser non-contact cutting methods. For example, referring to Figure 11, the negative electrode sheet 10S may be cut along the vertical direction TD (e.g., the +Y axis direction), thereby forming individual negative electrodes 10.

[0112] A method for manufacturing the negative electrode 10 according to one embodiment may include the method for manufacturing the negative electrode sheet 10S described above. The method for manufacturing the negative electrode 10 may also include cutting the negative electrode sheet 10S.

[0113] In one embodiment, the negative electrode 10 may include a margin region 235 in the second region 220, which is a region other than the negative electrode tab 230. Referring to Figure 11, at least a portion of the margin region 235 may be provided between the negative electrode tab 230 and the first metal layer 100. When viewed from the thickness direction of the first metal layer 100 (i.e., the +Z axis direction), at least a portion of the margin region 235 may be provided between the negative electrode tab 230 and the first metal layer 100. Also referring to Figure 11, at least a portion of the margin region 235 may be provided between the negative electrode tab 230 and the first region 210. When viewed from the thickness direction of the first metal layer 100 (i.e., the +Z axis direction), at least a portion of the margin region 235 may be provided between the negative electrode tab 230 and the first region 210. That is, referring to Figure 11, the first region 210 may be provided between the margin region 235 and the first metal layer 100. When viewed from the thickness direction of the first metal layer 100 (i.e., the +Z axis direction), the first region 210 can be provided between the margin region 235 and the first metal layer 100. Through this, the first metal layer 100, which is lithium metal, can be protected during the notching process, improving the stability of the process and improving the tensile strength of the negative electrode 10. In addition, through the margin region 235, it is possible to prevent lithium dendrites from directly contacting the positive electrode tab connected to the positive electrode (see 30 in Figure 36) and causing a short circuit. In particular, it is possible to effectively prevent the occurrence of a short circuit even in a unidirectional battery where the positive electrode tab and the negative electrode tab 230 are facing the same direction.

[0114] A unidirectional battery can mean a battery in which the positive electrode tab and the negative electrode tab 230 protrude from one side of the main body of the electrode assembly (see Figure 36-1) in the same direction. In other examples, a unidirectional battery may be a battery in which the positive electrode leads connected to one or more positive electrode tabs and protruding from one side of the main body of the electrode assembly (see Figure 36-1), and the negative electrode leads connected to one or more negative electrode tabs 230 and protruding from one side of the main body of the electrode assembly (see Figure 36-1), all oriented in the same direction.

[0115] On the other hand, as shown in Figure 11, cutting the negative electrode sheet 10S so that two tabs 230 are contained within one negative electrode 10 is merely illustrative. According to other embodiments, the negative electrode sheet 10S may also have cut points formed in units of three or more tabs (e.g., 10) to facilitate the formation of a negative electrode structure 10A as shown in Figure 36, which will be described later.

[0116] For example, the negative electrode sheet 10S can be cut into predetermined units after forming an electrode assembly (e.g., electrode assembly 1 in Figure 36) by interposing a positive electrode (e.g., positive electrode 30 in Figure 36) between two surfaces formed by a bend. Alternatively, in another example, the negative electrode sheet 10S may be cut in advance at a stage before interposing the positive electrode.

[0117] Figure 12 is a plan view illustrating at least a portion of the negative electrode 10 according to one embodiment of this application.

[0118] In one embodiment, the negative electrode 10 may include a plurality of second metal layers (e.g., a second-first metal layer 200a and a second-second metal layer 200b).

[0119] In one embodiment of the negative electrode 10, the first metal layer 100 may be interposed between a plurality of second metal layers (e.g., a second-first metal layer 200a and a second-second metal layer 200b).

[0120] For example, the negative electrode 10 according to one example may include a first metal layer 100 and a second metal layer 200 which includes a second-first metal layer 200a and a second-second metal layer 200b.

[0121] For example, each of the second-first metal layer 200a and the second-second metal layer 200b may overlap and bond with a portion of the first metal layer 100. Each of the second-first metal layer 200a and the second-second metal layer 200b may project in one direction from one side edge of the first metal layer 100.

[0122] For example, in the negative electrode 10, the second-first metal layer 200a and the second-second metal layer 200b can each overlap and bond with a portion of one side edge of the first metal layer 100.

[0123] In one embodiment of the negative electrode 10, the first metal layer 100 may be interposed between the second-first metal layer 200a and the second-second metal layer 200b.

[0124] In one embodiment of the negative electrode 10, the second-first metal layer 200a and the second-second metal layer 200b may be formed by overlapping and joining with a portion of the first metal layer 100. For example, each of the multiple second metal layers (e.g., the second-first metal layer 200a and the second-second metal layer 200b) may protrude in one direction from one side edge of the first metal layer 100.

[0125] According to various embodiments, the contents of the aforementioned second metal layer 200 can be referenced, as long as each of the multiple second metal layers (e.g., second-1 metal layer 200a and second-2 metal layer 200b) is not contradictory.

[0126] In one embodiment of the negative electrode 10, the tensile strength of the negative electrode 10 can be improved by interposing the first metal layer 100 between a plurality of second metal layers (e.g., the second-first metal layer 200a and the second-second metal layer 200b).

[0127] For example, multiple second metal layers (e.g., 2-1 metal layer 200a and 2-2 metal layer 200b) may be formed from other metals that are less reactive than lithium (Li) metal.

[0128] For example, multiple second metal layers (e.g., 200a, 200b) may be formed from at least one material selected from copper (Cu), nickel (Ni), or stainless steel.

[0129] In one embodiment, the second metal layers (e.g., 200a, 200b) can each have a variety of structures independently. Each of the second metal layers (e.g., 200a, 200b) may include one or more of a predetermined pattern structure and a surface-treated region. One or more of the predetermined pattern structure and surface-treated region may be included in the first regions 210a, 210b of the second metal layer (e.g., 200a, 200b).

[0130] For example, each second metal layer (e.g., 200a, 200b) can independently include a predetermined pattern structure in at least a portion of its area (e.g., at least a portion of the area in contact with the first metal layer 100). The pattern structure may be, for example, a mesh structure or a structure with a grid pattern formed on its surface, or it may have all of these structures. For example, a mesh structure may mean a structure with multiple holes, and a grid pattern may mean a structure with multiple grooves. Through this, the contact area between the first metal layer 100 and the second metal layer (e.g., 200a, 200b) can be maximized to improve the bonding strength.

[0131] Furthermore, at least a portion of the second metal layer (e.g., 200a, 200b) (for example, at least a portion of the area of ​​the second metal layer (e.g., 200a, 200b) that is in contact with the first metal layer 100) may be surface-treated. Surface treatment can be carried out, for example, by plasma treatment. If surface-treated, it can have a different surface roughness than other areas. Through such appropriate surface treatment, the bonding strength between the first metal layer 100 and the second metal layer (e.g., 200a, 200b) can be improved.

[0132] In one embodiment, each of the multiple second metal layers (e.g., 2-1 metal layer 200a and 2-2 metal layer 200b) may include first regions 210a, 210b (e.g., overlapping regions) that overlap with the first metal layer 100, and second regions 220a, 220b (e.g., non-overlapping regions) that are regions other than the first regions 210a, 210b. For example, with respect to the thickness direction of the first metal layer 100 (e.g., the +Z axis direction in Figure 12), each of the multiple second metal layers (e.g., 2-1 metal layer 200a and 2-2 metal layer 200b) may include first regions 210a, 210b (e.g., overlapping regions) that overlap with the first metal layer 100, and second regions 220a, 220b (e.g., non-overlapping regions) that are regions other than the first regions 210a, 210b.

[0133] In one embodiment, at least one of a plurality of second metal layers (e.g., 2-1 metal layer 200a and 2-2 metal layer 200b) has a widthwise length W of the first region 210a, 210b (e.g., overlapping region) that overlaps with the first metal layer 100. a1 , W b1 The widthwise length W of the second region 220a, 220b (e.g., non-overlapping region), which is a region other than the first region 210a, 210b. a2 , W b2 It can be formed to be shorter than that.

[0134] In the second metal layer 200a of one embodiment, the length W in the width direction of the first region 210a a1 The length W is the width direction of the second region 220a. a2 It may be shorter than that. Also, in the second-second metal layer 200b, the length W in the width direction of the first region 210b b1 The width direction length W of the second region 220b is b2 It may be shorter than the length W in the width direction of the first region 210a, 210b. a1 , W b1 The length W in the width direction of the second region 220a, 220b a2 , W b2 By making it shorter, the size of the negative electrode 10 can be minimized while maximizing the capacity.

[0135] In the second metal layer 200a according to one embodiment, the length W in the width direction of the second region 220a a2 and the width direction length W of the first region 210a a1 The ratio W a2 / W a1 This can be greater than 1 and less than or equal to 20, 2 or more and less than or equal to 18, or 5 or more and less than or equal to 16. Also, in the second-second metal layer 200b, the length W in the width direction of the second region 220b is... b2 and the width direction length W of the first region 210b b1 The ratio W b2 / W b1 The ratio W may be greater than 1 and less than or equal to 20, 2 or more and less than or equal to 18, or 5 or more and less than or equal to 16. a2 / W a1 , W b2 / W b1 If the above range is met, the capacity can be maximized while minimizing the size of the negative electrode 10.

[0136] In the second-first metal layer 200a according to one embodiment, the length W in the width direction of the first region 210a a1 and the width direction length W of the second-first metal layer 200a aT The ratio W a1 / W aT This can be 0.01~0.1, 0.02~0.09, 0.03~0.08, or 0.04~0.07. Also, in the second-second metal layer 200b, the length W in the width direction of the first region 210b is... b1 and the width direction length W of the second-second metal layer 200b bT The ratio W b1 / W bT The ratio W may be 0.01-0.1, 0.02-0.09, 0.03-0.08, or 0.04-0.07. a1 / W aT , W b1 / W bT If the above range is met, sufficient bonding strength can be ensured between the first metal layer 100 and the second-first metal layer 200a, and between the first metal layer 100 and the second-second metal layer 200b.

[0137] In one embodiment of the negative electrode 10, a first region 210a, 210b (e.g., overlapping region) that overlaps with at least one of a plurality of second metal layers (e.g., second-first metal layer 200a and second-second metal layer 200b) with the first metal layer 100 may be embedded in the first metal layer 100.

[0138] In one embodiment of the negative electrode 10, the first region 210a of the second-first metal layer 200a may be embedded in the first metal layer 100. For example, the upper surface of the second-first metal layer 200a and the upper surface of the first metal layer 100 may be located on the same plane. That is, the first region 210a of the second-first metal layer 200a may be embedded in the first metal layer 100, and there may not be an upper step between the second-first metal layer 200a and the first metal layer 100.

[0139] In one embodiment of the negative electrode 10, the first region 210b of the second-second metal layer 200b may be embedded in the first metal layer 100. The lower surface of the second-second metal layer 200b and the lower surface of the first metal layer 100 can be substantially coplanar. For example, the second-second metal layer 200b may not have a lower step between the second-second metal layer 200b and the first metal layer 100, even though the first region 210b is embedded in the first metal layer 100.

[0140] Through the configurations of the second-first metal layer 200a and the second-second metal layer 200b described above, the first metal layer 100 may be rewinded after being joined to the second-first metal layer 200a or the second-second metal layer 200b. In this case, not only is the problem of meandering, where the alignment between the metal layers is misaligned, but the problem of the electrodes twisting due to meandering can also be prevented. Furthermore, through this configuration, as described above, when unwinding is performed after rewinding to manufacture the negative electrode structure (see 10A in Figure 36) described later, the problem of meandering can be prevented. In addition, through this configuration, if there is a step (especially if it is thicker than the thickness of the positive electrode (see 30 in Figure 36) described later), the problem of the stack portion 10A_S of the negative electrode structure (see 10A in Figure 36) excessively protruding and reducing the energy density per unit volume of the battery cell can be prevented.

[0141] In a negative electrode 10 according to one embodiment, the first regions 210a and 210b (e.g., overlapping regions) of a plurality of second metal layers (e.g., second-first metal layer 200a and second-second metal layer 200b) that overlap with the first metal layer 100 have substantially the same widthwise length W. a1 , W b1 It can have.

[0142] In the negative electrode 10 according to one embodiment, the length W in the width direction of the first region 210a of the second-first metal layer 200a a1 and the width direction length W of the first region 210b of the second-second metal layer 200b b1 They can be substantially identical. Substantially identical means that the length W in the width direction of the first region 210a of the second-first metal layer 200a is the same. a1 and the width direction length W of the first region 210b of the second-second metal layer 200b b1 Whether they are the same or different, it can be said that R, calculated using Equation 1 below, is 10% or less. Such a configuration may be advantageous for manufacturing a negative electrode structure including the folding and stacking sections described later (see 10A in Figure 36).

[0143] [Formula 1] R=|W a1 -W b1 | / W a1 ×100

[0144] In Equation 1, W a1 This is the length in the width direction of the first region 210a of the second-first metal layer 200a, and W b1 This can mean the length in the width direction of the first region 210b of the second-second metal layer 200b.

[0145] Referring to Figure 12, in the negative electrode 10 according to one embodiment, the length W in the width direction of the second region 220a of the second-first metal layer 200a is shown. a2 and the width direction length W of the second region 220b of the second metal layer 200b b2 They can be substantially identical. Substantially identical means that the length W in the width direction of the second region 220a of the second-first metal layer 200a is substantially identical. a2 and the width direction length W of the second region 220b of the second metal layer 200b b2 Whether they are the same or different, it can be said that R' calculated using equation 2 below is 10% or less.

[0146] [Formula 2] R'=|W a2 -W b2 | / W a2 ×100

[0147] In Equation 2, W a2 This is the widthwise length of the second region 220a of the second-first metal layer 200a, and W b2 This can mean the length in the width direction of the second region 220b of the second-2 metal layer 200b.

[0148] Unlike Figure 12, in the negative electrode 10 according to another embodiment, the widthwise length W of the second region 220a of the second-first metal layer 200a a2 and the width direction length W of the second region 220b of the second metal layer 200b b2 These can differ. For example, the widthwise length W of the second region 220a of the second-first metal layer 200a. a2This is the widthwise length W of the second region 220b of the second-second metal layer 200b. b2 It may be larger than this. Here, a negative electrode tab (see 230a in Figure 22) described later may be formed on the second-first metal layer 200a, which has a larger length in the width direction, and a negative electrode tab described later may not be formed on the second-second metal layer 200b, which has a smaller length in the width direction. In one example, the length W in the width direction of the second region 220b of the second-second metal layer 200b. b2 This is the widthwise length W of the first region 210b of the second-second metal layer 200b. b1 It can be shorter than that. For example, in this case, the second-second metal layer 200b may only exist in the first region 210b.

[0149] In one example, the thickness of the first metal layer 100 may be greater than the thickness of one or more of the second metal layers (e.g., the second-first metal layer 200a and the second-second metal layer 200b). For example, the thickness of the first metal layer 100 may be greater than the sum of the thicknesses of the second-first metal layer 200a and the second-second metal layer 200b. Through this, the tensile strength of the negative electrode 10 can be improved.

[0150] In a negative electrode 10 according to one embodiment, negative electrode tabs (first negative electrode tab (230a in Figure 22), second negative electrode tab) can be formed in at least a portion of one or more second regions 220a, 220b (e.g., non-overlapping regions) of a plurality of second metal layers (e.g., second-first metal layer 200a and second-second metal layer 200b). For example, negative electrode tabs (first negative electrode tab (230a in Figure 22), second negative electrode tab) can be formed by performing a notching process on one or more second regions 220a, 220b (e.g., non-overlapping regions) of the second metal layers (e.g., second-first metal layer 200a and second-second metal layer 200b). In other words, the negative electrode 10 may include negative electrode tabs (first negative electrode tab (230a in Figure 22), second negative electrode tab) formed in one or more second regions 220a, 220b (e.g., non-overlapping regions) of the second metal layer (e.g., second-first metal layer 200a and second-second metal layer 200b).

[0151] In the negative electrode 10 according to one embodiment, the negative electrode tabs (first negative electrode tab (230a in Figure 22), second negative electrode tab) can each be formed independently in multiple units. Here, the notching process is not particularly limited, but can be performed by a contact method such as a notching device or a non-contact method utilizing a laser. The negative electrode 10 may include multiple negative electrode tabs (first negative electrode tab (230a in Figure 22), second negative electrode tab) formed in one or more second regions 220a, 220b (e.g., non-overlapping regions) of the second metal layer (e.g., second-1 metal layer 200a and second-2 metal layer 200b).

[0152] In various embodiments, the second metal layer (e.g., the second-first metal layer 200a and the second-second metal layer 200b) is formed of a metal material that is relatively less reactive than lithium metal, so that even if the notching process is performed in a non-contact manner, the occurrence of safety problems due to dust can be minimized.

[0153] Figures 13 and 14 illustrate a part of the manufacturing process of a negative electrode sheet (see 10S in Figure 22) according to the fourth embodiment of this application, and the explanation therefor can be found in the explanations in Figures 2 and 3, to the extent that they do not contradict each other. Referring to Figure 13, the second-first metal layer 200a and the second-second metal layer 200b may be positioned above or below the first metal layer 100, respectively, while sandwiching the first metal layer 100, so as to overlap a portion of one side edge of the first metal layer 100. The second-first metal layer 200a and the second-second metal layer 200b may be transported in the same direction via a transport roll (not shown). Furthermore, the transport direction of the first metal layer 100 may be the same as the transport direction of the second-first metal layer 200a and the second-second metal layer 200b.

[0154] In one embodiment, referring to Figure 14, the first metal layer 100 and the second-first metal layer 200a, and the first metal layer 100 and the second-second metal layer 200b can each be rolled by a roller R. Specifically, the overlapping regions of the first metal layer 100 and the second-first metal layer 200a, and the first metal layer 100 and the second-second metal layer 200b can be joined together by applying pressure with the roller R.

[0155] Figures 15 to 17 illustrate a part of the manufacturing process of a negative electrode sheet (see 10S in Figure 22) according to the fifth embodiment of this application. The rollers R can roll a portion of one side edge of the first metal layer 100 as it is transported in the +X axis direction. Multiple rollers R are provided to roll the entire upper and lower surfaces of the first metal layer 100. Referring to Figure 16, the first metal layer 100 can have a first groove H1 formed on the upper side and a second groove H2 formed on the lower side formed by the rollers R. The second-first metal layer 200a can be introduced into the first groove H1, and the second-second metal layer 200b can be introduced into the second groove H2. Referring to Figure 17, the second-first metal layer 200a introduced into the first groove H1 and the second-second metal layer 200b introduced into the second groove H2 can each be joined to the first metal layer 100 via a joining means such as a laser device LA.

[0156] Figure 18 illustrates a part of the manufacturing process of a negative electrode sheet (see 10S in Figure 22) according to the sixth embodiment of this application. Referring to Figure 18, after the roller R rolls a portion of one side edge of the first metal layer 100 as shown in Figures 15 and 16, the binder B can be applied to the first groove H1 and second groove H2 formed by the rolling, and the second-first metal layer 200a and second-second metal layer 200b can be introduced onto the binder B and joined to the first metal layer 100.

[0157] Figures 19 and 20 illustrate a part of the manufacturing process of the negative electrode sheet 10S according to one embodiment of this application. Figure 21 is a plan view of Figure 20 and illustrates a part of the manufacturing process of the negative electrode sheet 10S according to one embodiment of this application.

[0158] Referring to Figure 19, the first metal layer 100 and the second-first metal layer 200a can be joined to each other using the method described above to form a joint boundary line CL. The joint boundary line CL can represent the end line of the first metal layer 100 in the region where the first metal layer 100 and the second-first metal layer 200a overlap. The second-second metal layer 200b can also be joined to the first metal layer 100 in the same way as the second-first metal layer 200a to form a joint boundary line CL. For example, the joint boundary line CL can represent the end line of the first metal layer 100 in the region where the first metal layer 100 and the second-first metal layer 200a overlap, with respect to the thickness direction of the first metal layer 100 (e.g., the +Z axis direction in Figure 19), and the same may be true for the second-second metal layer 200b.

[0159] Referring to Figures 20 and 21, a notching process can be performed on the negative electrode sheet 10S according to one embodiment using a laser device LA.

[0160] For example, the laser L generated in the laser device LA may irradiate the second region 220a of the second-first metal layer 200a, thereby partially cutting the second region 220a to form the first negative electrode tab (see 230a in Figure 22). The second-second metal layer 200b may be similar to the second-first metal layer 200a.

[0161] Figure 22 is a plan view illustrating at least a portion of the negative electrode sheet 10S according to one embodiment of this application. Figure 23 is a plan view showing how the negative electrode sheet (see 10S in Figure 22) is cut to form the negative electrode 10 according to one embodiment of this application.

[0162] In one embodiment, the negative electrode sheet 10S may have a first negative electrode tab 230a formed in the second region 220a of the second-first metal layer 200a, which includes a first tab 231a, a second tab 232a, and a third tab 233a. That is, the negative electrode sheet 10S may include a first negative electrode tab 230a formed in the second region 220a of the second-first metal layer 200a.

[0163] For example, in the second-first metal layer 200a, the second tab 232a and the third tab 233a, which are mutually adjacent on both sides with respect to the first tab 231a, can each be positioned at a predetermined distance from the first tab 231a. For example, the first length W is the distance between the first tab 231a and the second tab 232a. a12 The second length W is the distance between the first tab 231a and the third tab 233a. a13 It can be formed to be longer than that.

[0164] Although not shown separately in Figure 22, the second-second metal layer 200b, like the second-first metal layer 200a, may have a second negative electrode tab formed in the second region 220b of the second-second metal layer 200b, including a first tab, a second tab, and a third tab. That is, the negative electrode sheet 10S according to the embodiment may include a second negative electrode tab formed in the second region (220b in Figure 20) of the second-second metal layer 200b.

[0165] For example, in the 2-2 metal layer 200b, the second and third tabs, which are mutually adjacent on both sides of the first tab, can each be positioned at a predetermined distance from the first tab. For example, the 1b length, which is the distance between the first and second tabs, can be formed to be longer than the 2b length, which is the distance between the first cap and the third tab. Varying the distances between tabs in this way can be advantageous for aligning the tabs.

[0166] A negative electrode sheet 10S according to one embodiment may include negative electrode tabs (first negative electrode tab 230a, second negative electrode tab) formed in at least one second region (220a, 220b in Figure 20) of a plurality of second metal layers (second-first metal layer 200a, second-second metal layer 200b).

[0167] While not particularly limited, the first negative electrode tab of the second-first metal layer 200a and the second negative electrode tab of the second-second metal layer 200b may be joined in at least some areas at corresponding positions. For example, the first tab 231a of the second-first metal layer 200a may be joined to the first tab of the second-second metal layer 200b in at least some areas. This simplifies the tab structure and improves ease of manufacturing.

[0168] In one embodiment, the negative electrode sheet 10S may include margin regions (first margin region 235a, second margin region) provided adjacent to the first metal layer 100 in at least one second region (220a, 220b in Figure 20) of a plurality of second metal layers (second-first metal layer 200a, second-second metal layer 200b).

[0169] Specifically, the negative electrode sheet 10S according to one embodiment may further include a first margin region 235a, which is a region in the second region 220a of the second-first metal layer 200a other than the region corresponding to the first negative electrode tab 230a. Referring to Figure 22, at least a portion of the first margin region 235a may be provided between the first negative electrode tab 230a and the first metal layer 100. When viewed from the thickness direction of the first metal layer 100 (i.e., the +Z axis direction), at least a portion of the first margin region 235a may be provided between the first negative electrode tab 230a and the first metal layer 100. Also, referring to Figure 22, at least a portion of the first margin region 235a may be provided between the first negative electrode tab 230a and the first region 210 of the second-first metal layer 200a.

[0170] For example, when viewed from the thickness direction of the first metal layer 100 (i.e., the +Z axis direction), at least a portion of the first margin region 235a may be provided between the first negative electrode tab 230a and the first region 210a of the second-first metal layer 200a. That is, referring to Figure 22, the first region 210a of the second-first metal layer 200a may be provided between the first margin region 235a and the first metal layer 100. When viewed from the thickness direction of the first metal layer 100 (i.e., the +Z axis direction), the first region 210a of the second-first metal layer 200a may be provided between the first margin region 235a and the first metal layer 100. Through this, if the manufacturing process of the negative electrode sheet 10S is carried out in a roll-to-roll manner, the stretching of the first metal layer 100, which is lithium metal, in the mechanical direction MD is suppressed, and an advantageous effect can be obtained during the continuous notching process.

[0171] The above description relating to the second-first metal layer 200a may also apply to the second-second metal layer 200b. Specifically, in the description relating to the second-first metal layer 200a, the second-first metal layer 200a may be the second-second metal layer 200b, the first negative electrode tab 230a may be the second negative electrode tab, and the first margin region 235a may be the second margin region. In one embodiment of the negative electrode sheet 10S, each of the second region 220a of the second-first metal layer 200a and the second region (220b in Figure 20) of the second-second metal layer 200b may include a margin region (e.g., 235a) provided adjacent to the first metal layer 100. Here, the margin region (e.g., 235a) may be a region other than the region in the second region 220a of the second-first metal layer 200a and the second region (220b in Figure 20) of the second-second metal layer 200b where the negative electrode tabs (e.g., first negative electrode tab 230a, second negative electrode tab) are formed by the notching process. Furthermore, as mentioned above, multiple negative electrode sheets 10S can be stacked in one direction (for example, according to the thickness direction of the first metal layer 100 (i.e., the +Z axis direction) or folded) and the notching process can be performed all at once to form the negative electrode tabs (e.g., first negative electrode tab 230a, second negative electrode tab). Through this, the process can be simplified and the tab alignment mismatch phenomenon that occurs when the negative electrode tabs (e.g., first negative electrode tab 230a, second negative electrode tab) are formed in advance can be minimized.

[0172] A negative electrode sheet 10S according to one embodiment can be cut via a cutting machine (not shown) according to predetermined rules. The predetermined rules are not limited but may be, for example, for standardizing the negative electrodes 10 to be formed, see Figure 23. The cutting machine may be, but is not limited to, one or more of the following: blade contact and laser non-contact cutting methods. Referring to Figure 23, the negative electrode sheet 10S may be cut along the vertical direction TD (e.g., the +Y axis direction), thereby forming individual negative electrodes 10.

[0173] In one embodiment, the negative electrode sheet 10 may include negative electrode tabs (first negative electrode tab 230a, second negative electrode tab) formed in at least one second region (220a, 220b in Figure 20) of the plurality of second metal layers (second-first metal layer 200a, second-second metal layer 200b). In addition, the negative electrode 10 in one embodiment may include margin regions (first margin region 235a, second margin region) provided adjacent to the first metal layer 100 in at least one second region (220a, 220b in Figure 20) of the plurality of second metal layers (second-first metal layer 200a, second-second metal layer 200b).

[0174] In one embodiment, the negative electrode 10 may include margin regions (first margin region 235a, second margin region) in at least one second region (220a, 220b in Figure 20) among a plurality of second metal layers (second-first metal layer 200a, second-second metal layer 200b), which are regions other than the negative electrode tabs (first negative electrode tab 230a, second negative electrode tab).

[0175] Specifically, in one embodiment, the negative electrode 10 may include a first margin region 235a, which is a region other than the first negative electrode tab 230a in the second region 220a of the second-first metal layer 200a. Referring to Figure 23, at least a portion of the first margin region 235a may be provided between the first negative electrode tab 230a and the first metal layer 100. When viewed from the thickness direction of the first metal layer 100 (i.e., the +Z axis direction), at least a portion of the first margin region 235a may be provided between the first negative electrode tab 230a and the first metal layer 100. Also, referring to Figure 23, at least a portion of the first margin region 235a may be provided between the first negative electrode tab 230a and the first region 210 of the second-first metal layer 200a. When viewed from the thickness direction of the first metal layer 100 (i.e., the +Z axis direction), at least a portion of the first margin region 235a may be provided between the first negative electrode tab 230a and the first region 210a of the second-first metal layer 200a. That is, referring to Figure 23, the first region 210a of the second-first metal layer 200a may be provided between the first margin region 235a and the first metal layer 100. When viewed from the thickness direction of the first metal layer 100 (i.e., the +Z axis direction), the first region 210a of the second-first metal layer 200a may be provided between the first margin region 235a and the first metal layer 100. Through this, the first metal layer 100, which is lithium metal, can be protected during the notching process, improving process stability and improving the tensile strength of the negative electrode 10.

[0176] The above description regarding the second-first metal layer 200a may also apply to the second-second metal layer 200b. Specifically, in the description regarding the second-first metal layer 200a, the second-first metal layer 200a may be the second-second metal layer 200b, the first negative electrode tab 230a may be the second negative electrode tab, and the first margin region 235a may be the second margin region.

[0177] Furthermore, the margin regions (first margin region 235a, second margin region) prevent lithium dendrites from directly contacting the positive electrode tab connected to the positive electrode (see 30 in Figure 36), thus preventing short circuits. In particular, short circuits can be effectively prevented even in unidirectional batteries where the positive electrode tab and the negative electrode tab (first negative electrode tab 230a, second negative electrode tab) face the same direction.

[0178] On the other hand, as illustrated in Figure 23, cutting the negative electrode sheet 10S so that two tabs 230 are contained within one negative electrode 10 is merely illustrative. According to other embodiments, the negative electrode sheet 10S may also have cut points formed in units of three or more tabs (e.g., 10) to facilitate the formation of a negative electrode structure 10A as shown in Figure 36, which will be described later.

[0179] For example, the negative electrode sheet 10S may be cut into predetermined units after a positive electrode (e.g., the positive electrode 30 in Figure 36) is interposed between two surfaces formed by a bend. In another example, the negative electrode sheet 10S may be cut in advance at a stage before the positive electrode is interposed.

[0180] Figure 24 is a plan view illustrating at least a portion of the negative electrode 10 according to one embodiment of this application.

[0181] In one embodiment, the negative electrode 10 may include a plurality of first metal layers (e.g., a first-first metal layer 100a and a first-second metal layer 100b). In the negative electrode 10, a second metal layer 200 may be interposed between a plurality of first metal layers (e.g., a first-first metal layer 100a and a first-second metal layer 100b).

[0182] For example, the negative electrode 10 according to one example may include a first metal layer 100 and a second metal layer 200, which include a first-1 metal layer 100a and a first-2 metal layer 100b. For example, the second metal layer 200 may be formed by overlapping and bonding with a portion of each of the first-1 metal layer 100a and the first-2 metal layer 100b. The second metal layer 200 may protrude in one direction from one side end of each of the first-1 metal layer 100a and the first-2 metal layer 200b. Also, for example, in the negative electrode 10, the second metal layer 200 may be formed by overlapping and bonding with a portion of each of the first-1 metal layer 100a and the first-2 metal layer 100b.

[0183] In one embodiment of the negative electrode 10, the second metal layer 200 may be interposed between the first-first metal layer 100a and the first-second metal layer 100b.

[0184] In one embodiment of the negative electrode 10, the second metal layer 200 may be formed by overlapping and joining with a portion of the first-1 metal layer 100a and the first-2 metal layer 100b. For example, the second metal layer 200 may project in one direction from one side end of each of the multiple first metal layers (e.g., the first-1 metal layer 100a and the first-2 metal layer 100b).

[0185] According to various embodiments, each of the multiple first metal layers (e.g., 1-1 metal layer 100a and 1-2 metal layer 100b) can refer to the contents of the first metal layer 100 described above, as long as they do not contradict each other.

[0186] In the negative electrode 10 according to one embodiment, interposing a second metal layer 200 between a plurality of first metal layers (e.g., 1-1 metal layer 100a and 1-2 metal layer 100b) provides various advantages. For example, when the positive electrode faces both sides of the negative electrode 10, the positive electrode can fully utilize the area of ​​the first metal layers (e.g., 1-1 metal layer 100a and 1-2 metal layer 100b), shortening the overall length of the battery cell and thus improving the energy density per unit weight and energy density per unit volume. Furthermore, minimizing the bias of the negative electrode tab (see 230 in Figure 34) to one side may enable a simpler process or design. Additionally, the tensile strength of the negative electrode 10 can be improved.

[0187] For example, multiple first metal layers (e.g., 1-1 metal layer 100a and 1-2 metal layer 100b) may be formed of lithium metal (Li metal).

[0188] According to various embodiments, the second metal layer 200 may be formed from a material other than lithium metal. For example, the second metal layer 200 may be formed from another metal that is less reactive than lithium (Li) metal. Alternatively, for example, the second metal layer 200 may be formed from at least one of copper (Cu), nickel (Ni), or stainless steel.

[0189] In one embodiment, the second metal layer 200 can have a variety of structures. The second metal layer 200 may include one or more of a predetermined pattern structure and a surface-treated region. One or more of the predetermined pattern structure and the surface-treated region may be included in at least a portion of the first region 210.

[0190] For example, at least a portion of the second metal layer 200 (for example, at least a portion of the portion in contact with the first metal layer (1-1 metal layer 100a or 1-2 metal layer 100b)) may include a predetermined pattern structure. The pattern structure may be, for example, a mesh structure or a structure with a grid pattern formed on its surface, and all of these structures may be present. For example, a mesh structure may mean a structure with multiple holes, and a grid pattern may mean a structure with multiple grooves. Through this, the contact area between the first metal layer (1-1 metal layer 100a or 1-2 metal layer 100b) and the second metal layer 200 can be maximized to improve bonding strength.

[0191] Furthermore, at least a portion of the second metal layer 200 (for example, at least a portion of the portion of the second metal layer 200 that is in contact with the first metal layer (the 1-1 metal layer 100a or the 1-2 metal layer 100b)) may be surface-treated. Surface treatment can be carried out, for example, by plasma treatment. Surface treatment can result in a different surface roughness than other areas. Through such appropriate surface treatment, the bonding strength between the first metal layer 100 and the second metal layer 200 can be improved.

[0192] In one example, the thickness of the first metal layer (1-1 metal layer 100a or 1-2 metal layer 100b) may be greater than the thickness of the second metal layer 200. Also, for example, the thicknesses of 1-1 metal layer 100a and 1-2 metal layer 100b may each be greater than the thickness of the second metal layer 200. Through this, the tensile strength of the negative electrode 10 can be improved.

[0193] In one embodiment of the negative electrode 10, the second metal layer 200 may include a first region 210 (e.g., overlapping region) that overlaps with a plurality of first metal layers (e.g., the 1-1 metal layer 100a or the 1-2 metal layer 100b) and a second region 220 (e.g., non-overlapping region) that is a region other than the first region 210. For example, with respect to the thickness direction of the first metal layer (e.g., the +Z axis direction in Figure 24), the second metal layer 200 may include a first region 210 (e.g., overlapping region) that overlaps with a plurality of first metal layers (e.g., the 1-1 metal layer 100a or the 1-2 metal layer 100b) and a second region 220 (e.g., non-overlapping region) that is a region other than the first region 210.

[0194] In one embodiment, if there are multiple first metal layers 100, the second metal layer 200 can have a first region 210 and a second region 220 determined based on each first metal layer 100. For example, the first region 210 where the second metal layer 200 overlaps with the first-first metal layer 100a (e.g., overlapping region) and the first region 210 where the second metal layer 200 overlaps with the first-second metal layer 100b (e.g., overlapping region) may be the same. However, although the drawings show the first region 210 where the second metal layer 200 overlaps with the first-first metal layer 100a (e.g., overlapping region) and the first region 210 where the second metal layer 200 overlaps with the first-second metal layer 100b (e.g., overlapping region) as the same, the representation is not limited to this, and they may be different.

[0195] On the other hand, if the negative electrode 10 according to one embodiment includes a plurality of first metal layers 100, the relationship between the second metal layer 200 and the first region 210 (e.g., overlapping region) and the second region 220 (e.g., non-overlapping region) of each first metal layer 100 can independently satisfy the above conditions.

[0196] In one embodiment, at least one of the second metal layer 200 and a plurality of first metal layers (e.g., 1-1 metal layer 100a and 1-2 metal layer 100b) may be formed such that the widthwise length W1 of the overlapping first region (e.g., overlapping region) is shorter than the widthwise length W2 of the second region (e.g., non-overlapping region), which is a region other than the first region (e.g., overlapping region).

[0197] For example, in each of the second metal layer 200 and the first-first metal layer 100a and the second metal layer 200 and the first-second metal layer 100b, the widthwise length W1 of the first region 210 may be shorter than the widthwise length W2 of the second region 220, and the ratio W2 / W1 of the widthwise length W2 of the second region 220 to the widthwise length W1 of the first region 210 may also satisfy the aforementioned range. Furthermore, in each of the second metal layer 200 and the first-first metal layer 100a and the second metal layer 200 and the first-second metal layer 100b, the widthwise length W1 of the first region 210 and the aforementioned ratio W2 / W1 may independently satisfy the aforementioned conditions.

[0198] In one embodiment of the negative electrode 10, the first region 210 (e.g., overlapping region) of the second metal layer 200 may be embedded in at least one of a plurality of first metal layers 100a, 100b.

[0199] In one embodiment of the negative electrode 10, the first region 210 of the second metal layer 200 may be embedded in the 1-1 metal layer 100a and the 1-2 metal layer 100b. For example, the first region 210 of the second metal layer 200 may be embedded while superimposed on the 1-1 metal layer 100a and the 1-2 metal layer 100b.

[0200] On the other hand, in the negative electrode 10 according to one embodiment, a plurality of first metal layers 100a, 100b may be joined at least in part in areas other than the area that fills the first region 210 (e.g., overlapping region) of the second metal layer 200. For example, a plurality of first metal layers 100a, 100b may be joined at least partially in positions corresponding to the second region 220 (e.g., non-overlapping region) of the second metal layer 200.

[0201] In one embodiment of the negative electrode 10, the first-1 metal layer 100a and the first-2 metal layer 100b may be joined at least in part in areas other than the area in which the first region 210 of the second metal layer 200 is embedded. For example, the first-1 metal layer 100a and the first-2 metal layer 100b may be joined at least in part in a position corresponding to the second region 220 (e.g., non-overlapping region) of the second metal layer 200. That is, the first-1 metal layer 100a and the first-2 metal layer 100b may be in contact with each other and laminated in a region that does not correspond to the first region 210 of the second metal layer 200 (i.e., the second region 220 (e.g., non-overlapping region)).

[0202] In the negative electrode 10 according to one embodiment, a negative electrode tab (see 230 in Figure 34) may be formed in at least a portion of the second region 220 (e.g., non-overlapping region) of the second metal layer 200. For example, a negative electrode tab (see 230 in Figure 34) can be formed by performing a notching process on the second region 220 of the second metal layer 200. That is, the negative electrode 10 may include a negative electrode tab (see 230 in Figure 34) formed in the second region 220 of the second metal layer 200.

[0203] In one embodiment of the negative electrode 10, a plurality of negative electrode tabs (see 230 in Figure 34) may be formed. Here, the notching process is not particularly limited, but can be performed by a contact method such as a notching device or a non-contact method utilizing a laser. The negative electrode 10 may include a plurality of negative electrode tabs (230 in Figure 34) formed in the second region 220 of the second metal layer 200.

[0204] In various embodiments, the second metal layer 200 is formed of a metal material that is relatively less reactive than lithium metal, so that even if the notching process is performed in a non-contact manner, the occurrence of safety problems due to dust can be minimized.

[0205] Figures 25 and 26 illustrate a part of the manufacturing process of a negative electrode sheet (see 10S in Figure 34) according to the seventh embodiment of this application, and the description thereof can be made by referring to the description in Figures 13 and 14, to the extent that it does not contradict the description. Referring to Figure 25, the second metal layer 200 may overlap with a portion of one side edge of the first metal layer 100a and the first metal layer 100b, respectively. Also, with the second metal layer 200 placed between the first metal layer 100a and the first metal layer 100b, the first metal layer 100a and the first metal layer 100b may be positioned above or below the second metal layer 200, respectively. The first metal layer 100a and the first metal layer 100b may be transported in the same direction via a transport roll (not shown).

[0206] For example, the transport direction of the second metal layer 200 may be the same as the transport direction of the first-first metal layer 100a and the first-second metal layer 100b. On the other hand, as will be described later, when the second metal layer 200 is introduced to the first-first metal layer 100a and the first-second metal layer 100b, the first-first metal layer 100a and the first-second metal layer 100b may come into contact with each other and be laminated together.

[0207] In one embodiment, referring to Figure 26, the first-first metal layer 100a and the second metal layer 200, and the first-second metal layer 100b and the second metal layer 200 can each be rolled by a roller R. Specifically, the overlapping regions of the first-first metal layer 100a and the second metal layer 200, and the first-second metal layer 100b and the second metal layer 200 can be joined together by applying pressure with the roller R.

[0208] Figures 27 to 29 illustrate a part of the manufacturing process of a negative electrode sheet (see 10S in Figure 34) according to the eighth embodiment of this application. The roller R can roll a portion of one side edge of each of the first-1 metal layer 100a and the first-2 metal layer 100b that are being transported in the +X direction. Multiple rollers R are provided to roll the lower surface of the first-1 metal layer 100a and the upper surface of the first-2 metal layer 100b, respectively. Referring to Figure 28, the first-1 metal layer 100a has groove A H on its lower side due to the roller R.A A first- and second metal layer 100b may be formed, and the upper side of the first B groove H is formed by the roller R. B Groove A H may be formed. A and groove H B A second metal layer 200 can be introduced into each of them. Referring to Figure 29, groove A H A and groove H B The second metal layer 200 introduced therein can be bonded to the first-1 metal layer 100a and the first-2 metal layer 100b via bonding means such as a laser device LA.

[0209] Figure 30 illustrates a part of the manufacturing process of the negative electrode sheet (see 10S in Figure 34) according to the ninth embodiment of this application. Referring to Figure 30, as shown in Figures 27 and 28, the roller R rolls a portion of one side edge of the first-first metal layer 100a and the first-second metal layer 100b, and then the A groove H is formed by rolling. A and groove H B Binder B can be applied to each of the layers, and a second metal layer 200 can be introduced onto the binder B to bond with the first-first metal layer 100a and the first-second metal layer 100b.

[0210] Figures 31 and 32 illustrate a part of the manufacturing process of the negative electrode sheet 10S according to one embodiment of this application. Figure 33 is a plan view of Figure 32 and illustrates a part of the manufacturing process of the negative electrode sheet 10S according to one embodiment of this application.

[0211] Referring to Figure 31, the first-first metal layer 100a and the second metal layer 200 can be joined to each other in the manner described above, forming a joint boundary line CL. The joint boundary line CL can represent the end line of the second metal layer 200 in the region where the first-first metal layer 100a and the second metal layer 200 overlap. For example, the joint boundary line CL can represent the end line of the first-first metal layer 100a in the region where the first-first metal layer 100a and the second metal layer 200 overlap, with reference to one thickness direction of the first metal layer (e.g., the +Z axis direction in Figure 31). The first-second metal layer 100b may be similar to the first-first metal layer 100a.

[0212] Referring to Figures 32 and 33, a notching process can be performed on the negative electrode sheet 10S according to one embodiment using a laser device LA.

[0213] For example, the laser L generated by the laser device LA may be irradiated onto a second region 220 of the second metal layer 200, thereby partially cutting the second region 220 to form a negative electrode tab (see 230 in Figure 34).

[0214] Figure 34 is a plan view illustrating at least a portion of the negative electrode sheet 10S according to one embodiment of this application. Figure 35 is a plan view illustrating, in one embodiment of this application, how the negative electrode sheet (see 10S in Figure 34) is cut to form the negative electrode 10.

[0215] In one embodiment, the negative electrode sheet 10S may have a negative electrode tab 230 formed in the second region 220 of the second metal layer 200. Specifically, the negative electrode tab 230 may include a first tab 231, a second tab 232, and a third tab 233 formed in the second region 220 of the second metal layer 200. That is, the negative electrode sheet 10S according to the embodiment may include a negative electrode tab 230 formed in the second region 220.

[0216] For example, in the second metal layer 200, the second tab 232 and the third tab 233, which are adjacent to each other on both sides with respect to the first tab 231, can each be positioned at a predetermined distance from the first tab 231. For example, the first length W is the distance between the first tab 231 and the second tab 232. 12 The second length W is the distance between the first tab 231 and the third tab 233. 13 It can be formed to be longer than this. Varying the distance between tabs in this way can be advantageous for aligning the tabs.

[0217] In one embodiment, the negative electrode sheet 10S may further include a margin region 235, which is a region in the second region 220 other than the region corresponding to the negative electrode tab 230. Referring to Figure 34, at least a portion of the margin region 235 may be provided between the negative electrode tab 230 and the first metal layer (1-1 metal layer 100a or 1-2 metal layer 100b). When viewed from one thickness direction of the first metal layer (1-1 metal layer 100a or 1-2 metal layer 100b) (i.e., the +Z axis direction), at least a portion of the margin region 235 may be provided between the negative electrode tab 230 and the first metal layer (1-1 metal layer 100a or 1-2 metal layer 100b). Also, referring to Figures 32 and 34, at least a portion of the margin region 235 may be provided between the negative electrode tab 230 and the first region 210.

[0218] For example, when viewed from one thickness direction (i.e., the +Z axis direction) of the first metal layer (1-1 metal layer 100a or 1-2 metal layer 100b), at least a portion of the margin region 235 may be provided between the negative electrode tab 230 and the first region 210. That is, referring to Figure 34, the first region 210 may be provided between the margin region 235 and one of the first metal layers (1-1 metal layer 100a or 1-2 metal layer 100b). When viewed from one thickness direction (i.e., the +Z axis direction) of the first metal layer (1-1 metal layer 100a or 1-2 metal layer 100b), the first region 210 may be provided between the margin region 235 and one of the first metal layers (1-1 metal layer 100a or 1-2 metal layer 100b). Through this process, if the manufacturing process of the negative electrode sheet 10S is carried out using a roll-to-roll method, the stretching of the first metal layer (1-1 metal layer 100a or 1-2 metal layer 100b), which is lithium metal, in the mechanical direction MD is suppressed, and advantageous effects can be obtained during the continuous notching process.

[0219] Although Figure 34 shows only the first metal layer 100a, it will be obvious to those skilled in the art that the second metal layer 100b may be similar to the first metal layer 100a.

[0220] In one embodiment, the negative electrode sheet 10S may include a margin region 235 provided adjacent to at least one of the first metal layers (1-1 metal layer 100a or 1-2 metal layer 100b) in the second region 220. Here, the margin region 235 may be a region in the second region 220 other than the region where the negative electrode tab 230 is formed by the notching process. Multiple negative electrode sheets 10S can be stacked in one direction (for example, according to one of the thickness directions (i.e., the +Z axis direction) of the first metal layer (1-1 metal layer 100a or 1-2 metal layer 100b) or folded) and the notching process can be performed all at once to form the negative electrode tab 230, thereby simplifying the process and minimizing the tab alignment mismatch phenomenon that occurs when the negative electrode tab 230 is formed in advance.

[0221] A negative electrode sheet 10S according to one embodiment can be cut via a cutting machine (not shown) according to predetermined rules. The predetermined rules are not limited but may be, for example, for standardizing the negative electrodes 10 to be formed, see Figure 35. The cutting machine may be, but is not limited to, one or more of the following: blade contact and laser non-contact cutting methods. Referring to Figure 35, the negative electrode sheet 10S can be cut along the vertical direction TD (e.g., the +Y axis direction), thereby forming individual negative electrodes 10.

[0222] In one embodiment, the negative electrode sheet 10 may include a negative electrode tab 230 formed in the second region 220. In addition, in the second embodiment, the negative electrode sheet 10 may include a margin region 235 provided adjacent to at least one of the plurality of first metal layers (first-first metal layer 100a or first-second metal layer 100b) in the second region 220.

[0223] In one embodiment, the negative electrode 10 may include a margin region 235 in the second region 220, which is a region other than the negative electrode tab 230. Referring to Figure 35, at least a portion of the margin region 235 may be provided between the negative electrode tab 230 and one of the first metal layers (1-1 metal layer 100a or 1-2 metal layer 100b). When viewed from the thickness direction (i.e., the +Z axis direction) of one of the first metal layers (1-1 metal layer 100a or 1-2 metal layer 100b), at least a portion of the margin region 235 may be provided between the negative electrode tab 230 and one of the first metal layers (1-1 metal layer 100a or 1-2 metal layer 100b). Also referring to Figure 35, at least a portion of the margin region 235 may be provided between the negative electrode tab 230 and the first region 210. When viewed from one of the thickness directions (i.e., the +Z axis direction) of the first metal layer (1-1 metal layer 100a or 1-2 metal layer 100b), at least a portion of the margin region 235 may be provided between the negative electrode tab 230 and the first region 210. That is, referring to Figure 35, the first region 210 may be provided between the margin region 235 and one of the first metal layers (1-1 metal layer 100a or 1-2 metal layer 100b). When viewed from one of the thickness directions (i.e., the +Z axis direction) of the first metal layer (1-1 metal layer 100a or 1-2 metal layer 100b), the first region 210 may be provided between the margin region 235 and one of the first metal layers (1-1 metal layer 100a or 1-2 metal layer 100b). Through this process, the first metal layer (1-1 metal layer 100a or 1-2 metal layer 100b), which is lithium metal, can be protected during the notching process, improving process stability and increasing the tensile strength of the negative electrode 10.

[0224] Furthermore, the margin region 235 prevents lithium dendrites from directly contacting the positive electrode tab connected to the positive electrode (see 30 in Figure 36), thus preventing short circuits. In particular, it can effectively prevent short circuits even in unidirectional batteries where the positive electrode tab and the negative electrode tab 230 face the same direction.

[0225] Although Figure 35 shows only the first metal layer 100a, it will be obvious to those skilled in the art that the second metal layer 100b may be similar to the first metal layer 100a.

[0226] On the other hand, as illustrated in Figure 35, cutting the negative electrode sheet 10S so that two tabs 230 are contained within one negative electrode 10 is merely illustrative. In other embodiments, the negative electrode sheet 10S may also have cut points in units of three or more tabs (e.g., 10) to facilitate the formation of a negative electrode structure 10A as shown in Figure 36, which will be described later.

[0227] For example, the negative electrode sheet 10S can be cut into predetermined units after forming an electrode assembly (e.g., electrode assembly 1 in Figure 36) by interposing a positive electrode (e.g., positive electrode 30 in Figure 36) between two surfaces formed by a bend. Alternatively, as another example, the negative electrode sheet 10S may be cut in advance at a stage before interposing the positive electrode.

[0228] Figure 36 is a plan view illustrating at least a portion of an electrode assembly 1 according to one embodiment of this application.

[0229] In various embodiments, the electrode assembly 1 may include a positive electrode 30, a negative electrode sheet 10S, and a negative electrode structure 10A comprising separation membranes 21 and 22.

[0230] In one embodiment, the negative electrode structure 10A may have a structure in which a negative electrode sheet 10S is interposed between two separation membranes 21 and 22.

[0231] In one embodiment, the negative electrode structure 10A may have a structure in which, instead of a negative electrode sheet 10S, a negative electrode 10 cut in the negative electrode sheet 10S is interposed between two separation membranes 21 and 22.

[0232] In one embodiment, the positive electrode 30 may include a positive electrode active material layer and a positive electrode current collector supporting the positive electrode active material layer. For example, the positive electrode 30 may have a structure in which the positive electrode active material layer is formed on at least one or both sides of the positive electrode current collector. The positive electrode active material layer includes a positive electrode active material and may further include a positive electrode binder, conductive material, and additives as needed.

[0233] The positive electrode current collector according to one embodiment is not particularly limited as long as it supports the positive electrode active material layer and is conductive without physical or chemical changes to the components contained in the electrode assembly 1 and the battery cell. For example, the positive electrode current collector can be made of aluminum, stainless steel, nickel, titanium, copper, palladium, calcined carbon, carbon, nickel, or silver, or surface-treated copper, stainless steel, or aluminum-cadmium alloy. The positive electrode current collector may also have fine irregularities formed on its surface, and its form can be diverse, such as a film, sheet, foil, mesh, net, or foam.

[0234] A positive electrode active material according to one embodiment may include a compound capable of reversibly intercalating and deintercalating lithium ions, sodium ions, or potassium ions. For example, a lithium, sodium, or potassium compound used as a positive electrode active material may have a layered structure, a crystalline structure, or a combination thereof. Furthermore, in this specification, the term "lithium compound" may encompass all forms of compounds in which auxiliary elements, coating elements, and doping elements are introduced or substituted around a main active element. The main active element may include, for example, one or more elements selected from the group consisting of nickel (Ni), cobalt (Co), manganese (Mn), and aluminum (Al). Auxiliary elements, coating elements, and doping elements are elements that can be combined with the main active element to improve the structural and chemical stability of the positive electrode active material, and can be distinguished by the manner in which they are combined with the main active element. Here, being combined with the main active element may include not only chemical bonding with the main active element, but also being present on the surface of the positive electrode active material or penetrating from the surface. Furthermore, for example, each of the auxiliary elements, coating elements, and doping elements may independently include one or more elements selected from the group consisting of Group 1 elements, Group 2 elements, Group 13 elements, Group 14 elements, Group 15 elements, Group 16 elements, and transition metals, excluding lithium. Specifically, for example, the auxiliary elements, coating elements, and doping elements may each independently include one or more selected from the group consisting of sodium (Na), magnesium (Mg), calcium (Ca), yttrium (Y), titanium (Ti), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), iron (Fe), copper (Cu), silver (Ag), zinc (Zn), boron (B), gallium (Ga), carbon (C), silicon (Si), tin (Sn), strontium (Sr), barium (Ba), radium (Ra), phosphorus (P), and zirconium (Zr).For example, the positive electrode active material may include one or more selected from the group consisting of nickel-cobalt-manganese oxide (NCM), nickel-cobalt-aluminum oxide (NCA), nickel-cobalt-manganese-aluminum oxide (NCMA), cobalt oxide (LCO), manganese oxide (LMO), and iron phosphate (LFP) bonded with lithium, sodium, or potassium.

[0235] The positive electrode active material according to one embodiment may contain a sulfur compound. The sulfur compound may be inorganic sulfur (Elemental sulfur, S8) or an organic sulfur compound Li2S x (x is, for example, 1 or more and 8 or less) and carbon-sulfur polymer ((C2S y ) n y = 2.5 to 50, n can include one or more of the following: 1 or more to 1, 000 or less, 1 or more to 100 or less, or 1 or more to 50 or less. If the positive electrode active material contains a sulfur compound, electrode assembly 1 can be applied to a lithium-sulfur (Li-S) battery.

[0236] A positive electrode binder according to one embodiment may include compounds that can improve the internal bonding force of the positive electrode active material layer and improve the adhesion force of the positive electrode active material layer to the positive electrode current collector. Examples of positive electrode binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, styrene butadiene rubber (SBR), polyethylene oxide, carboxymethyl cellulose (CMC), cellulose acetate, cellulose acetate butylate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, and cyanoethyl sucrose. It may contain one or more selected from the group consisting of sucrose, pullulan, polymethyl methacrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, and polyarylate.

[0237] The conductive material according to one embodiment may include a compound capable of improving the conductivity of the positive electrode active material layer and the mobility of ions or electrons. The conductive material may include, for example, carbon-based conductive materials such as graphite, carbon black, acetylene black, Ketjen black, graphene, carbon nanotube (CNT), VGCF (vapor-grown carbon fiber) and carbon fiber, and / or metal-based conductive materials including tin, tin oxide, titanium oxide, and perovskite materials such as LaSrCoO3 and LaSrMnO3. The carbon nanotube (CNT) may include one or more selected from the group consisting of Multi-Walled Carbon Nanotube (MWCNT) and Single-Walled Carbon Nanotube (SWCNT) according to the number of walls.

[0238] The separators 21 and 22 according to one embodiment may mean that a membrane that prevents an electrical short circuit between the cathode and the anode and allows electron transfer substances to pass through is provided in a sheet form. Here, the electron transfer substance is, for example, lithium ion (Li + ), sodium ion (Na + ) or potassium ion (K + ). The separators 21 and 22 are not particularly limited as long as they are those used in the relevant technical field, and those having low resistance to the movement of electrolyte ions and excellent moisture retention capacity (wettability) for the electrolyte (especially the electrolytic solution) are preferable. As the separators 21 and 22, a porous polymer film, for example, a porous polymer film made of a polyolefin material such as an ethylene polymer, a propylene polymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, or an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof may be used independently of each other.

[0239] The negative electrode structure 10A may be formed by the negative electrode 10 (or negative electrode sheet 10S) according to the embodiment of the present application. For example, the negative electrode 10 (or negative electrode sheet 10S) forming the negative electrode structure 10A may include a first metal layer 100 and a second metal layer 200 that is overlapped and joined to a partial region of one side end of the first metal layer 100. For example, the negative electrode 10 (or negative electrode sheet 10S) forming the negative electrode structure 10A may be interposed between two separation films 21 and 22, as illustrated in Figure 36. The negative electrode 10 (or negative electrode sheet 10S) according to one embodiment includes a plurality of second metal layers 200, and the first metal layer 100 may be interposed between the plurality of second metal layers 200. The negative electrode 10 (or negative electrode sheet 10S) according to another embodiment includes a plurality of first metal layers 100, and the second metal layer 200 may be interposed between the plurality of first metal layers 100.

[0240] The electrode assembly 1 according to one embodiment may be manufactured by, for example, bending the negative electrode structure 10A in a zigzag manner (folding), then inserting the positive electrode 30 cut to an appropriate size into the space formed by the bending. Since the negative electrode 10 (or negative electrode sheet 10S) forming the negative electrode structure 10A includes the first metal layer 100, it can be formed into a bent shape due to its brittle characteristic.

[0241] Compared with the negative electrode structure 10A, the positive electrode 30 is not easy to fold but is relatively easy to cut, so it can be used after being cut to an appropriate size as described above.

[0242] On the other hand, the negative electrode structure 10A including the sheet-shaped negative electrode 10 may be bent, and after an appropriate number of positive electrodes 30 are inserted between the surfaces formed by the bending, it may be cut within an appropriate range. For example, referring to Figure 36, after four positive electrodes 30 are inserted so that the negative electrode structure 10A entirely wraps the positive electrodes 30, both ends of the negative electrode structure 10A may be cut to manufacture individual electrode assemblies 1.

[0243] In one embodiment, the negative electrode structure 10A may include a stack portion 10A_S and a folding portion 10A_F. Multiple stack portions 10A_S and folding portions 10A_F may be provided. The stack portion 10A_S can form a stacked structure with the inserted positive electrode 30, and the folding portion 10A_F may represent a region in which the negative electrode structure 10A is folded. The electrode assembly 1 may have a structure in which the stack portions 10A_S of the negative electrode structure 10A and the positive electrode 30 are alternately stacked in sequence.

[0244] The electrode assembly 1 according to one embodiment is not limited to the method described above and can be assembled in a variety of ways. For example, the electrode assembly 1 can be assembled by first manufacturing a mono-cell by sequentially stacking a separation membrane, a negative electrode 10 (for example, each negative electrode 10 shown in Figures 11, 23, and 35), the separation membrane, and a positive electrode, or by sequentially stacking a bi-cell by sequentially stacking a negative electrode 10 (for example, each negative electrode 10 shown in Figures 11, 23, and 35), the separation membrane, and a positive electrode, then attaching a half-cell in which the separation membrane, negative electrode 10, and separation membrane are sequentially stacked to the mono-cell or bi-cell, and repeatedly stacking the mono-cell or bi-cell until the attached half-cell is reached. Alternatively, the electrode assembly 1 can be assembled by, for example, alternately stacking the negative electrode 10 (for example, each negative electrode 10 shown in Figures 11, 23, and 35) and positive electrode in a zigzag pattern between long sheet-like separation membranes. Even in the assembly method described above, the negative electrode 10 can minimize the double selection phenomenon due to its unique structure, and damage to its appearance during stacking can be reduced. The electrode assembly 1 according to one embodiment can be built into a case together with the electrolyte to manufacture a battery cell. Furthermore, a battery module, battery pack, or energy storage device can be manufactured using the battery cell.

[0245] In one embodiment, the battery cell may include a case containing the electrode assembly 1. The battery cell may also include an electrolyte within the case. The electrolyte may include one or more substances that are solid and liquid in a normal temperature and atmospheric pressure environment. For example, the electrolyte may include a liquid substance. The electrolyte may include a conductive salt and a solvent.

[0246] Conductive salts can contain electron transfer substances, such as MCl, MBr, MI, MClO4, MBF4, MB 10 Cl 10 The conductive salt may contain one or more of the following: MB(Ph)4 (where Ph is the phenol group), MC4BO8, MPF6, MCF3SO3, MCF3CO2, MAsF6, MSbF6, MAlCl4, MSO3CH3, MSO3CF3, MSCN, MC(CF3SO2)3, MN(CF3SO2)2, MN(C2F5SO2)2, MN(SO2F)2, chloroborane metal (M), lower aliphatic carboxylic acid metal (M), tetraphenylborate metal (M), and metal (M)imide, but is not particularly limited as long as it is readily soluble in organic solvents, and metal (M) is one of lithium (Li), sodium (Na), and potassium (K). The concentration of the conductive salt may be varied in the range of 0.1 to 10 M depending on various factors such as the solubility of the salt, the conductivity of the dissolved salt, the charging and discharging conditions of the battery, the operating temperature, and other factors known in the field of lithium secondary batteries.

[0247] The solvent may include one or more carbonate-based solvents, ether-based solvents, and ester-based solvents. The electrolyte may further include a suitable solvent considering appropriate viscosity and electrical conductivity.

[0248] The carbonate solvent may include one or more cyclic carbonate solvents and linear carbonate solvents. The cyclic carbonate solvent may include, for example, one or more of the following: ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate (1,2-BC), 2,3-butylene carbonate (2,3-BC), 1,2-pentylene carbonate (1,2-PTC), 2,3-pentylene carbonate (2,3-PTC), and vinylene carbonate (VC). Linear carbonate solvents may include, for example, one or more of the following: methyl carbonate, ethyl carbonate, dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC), and ethyl propyl carbonate (EPC).

[0249] The ether solvent may contain one or more of the following: dimethyl ether, diethyl ether, dipropyl ether, methylethyl ether, methylpropyl ether, and ethylpropyl ether.

[0250] The ester solvent may include one or more linear ester solvents and cyclic ester solvents. For example, the linear ester compound may include one or more of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate. The cyclic ester compound may also include one or more of gamma-butyrolactone, gamma-valerolactone, gamma-caprolactone, sigma-valerolactone, and epsilon-caprolactone.

[0251] In one embodiment, the electrolyte may optionally include the aforementioned sulfur compounds. In another embodiment, the electrolyte may optionally further include nitrate or nitrite compounds. For example, nitric acid or nitrite compounds may include, but are not particularly limited, inorganic nitric acid or nitrite compounds such as lithium nitrate (LiNO3), potassium nitrate (KNO3), cesium nitrate (CsNO3), barium nitrate (Ba(NO3)2), ammonium nitrate (NH4NO3), lithium nitrite (LiNO2), potassium nitrite (KNO2), cesium nitrite (CsNO2), and ammonium nitrite (NH4NO2); organic nitric acid or nitrite compounds such as methyl nitrate, dialkylimidazolium nitrate, guanidine nitrate, imidazolium nitrate, pyridinium nitrate, ethyl nitrate, propyl nitrate, butyl nitrate, pentyl nitrate, and octyl nitrate; and one or more organic nitro compounds such as nitromethane, nitropropane, nitrobutane, nitrobenzene, dinitrobenzene, nitropyridine, dinitropyridine, nitrotoluene, and dinitrotoluene.

[0252] In one embodiment, the electrolyte may further contain other additives to improve charge-discharge characteristics, flame retardancy, etc. Other additives may include, but are not limited to, one or more of the following: pyridine, triethyl phosphite, triethanolamine, cyclic ether, ethylenediamine, n-glyme, hexaphosphate triamide, nitrobenzene derivatives, sulfur, quinone imine dye, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, aluminum trichloride, fluoroethylene carbonate (FEC), and propensultone (PRS).

[0253] The negative electrode 10, negative electrode sheet 10S, and electrode assembly 1 according to one embodiment of this application can be widely applied in green technology fields such as electric vehicles, battery charging stations, and solar and wind power generation utilizing batteries. Furthermore, the negative electrode 10, negative electrode sheet 10S, and electrode assembly 1 according to one embodiment of this application can be applied to eco-friendly electric vehicles or hybrid vehicles that suppress air pollution and greenhouse gas emissions and prevent climate change.

[0254] Although various embodiments of this application have been described in detail above, the scope of rights of this application is not limited thereto, and it will be obvious to anyone with average knowledge of the art that various modifications and variations are possible without departing from the technical idea of ​​this application as described in the claims. Furthermore, some components may be omitted in the embodiments described above, and each embodiment may be implemented in combination with one another. [Explanation of symbols]

[0255] 1: Electrode assembly, 10: Negative electrode 10S: Negative electrode sheet, 100: First metal layer 100a: 1st-1st metal layer, 100b: 1st-2nd metal layer 200: 2nd metal layer, 200a: 2nd-1st metal layer 200b: 2nd-2nd metal layer, 210: 1st region 220: Second region, 230: Negative electrode tab

Claims

1. A first metal layer formed of lithium metal, It includes a plurality of second metal layers formed from a material other than lithium metal, which overlap and bond with a portion of the first metal layer, The first metal layer is a negative electrode interposed between the plurality of second metal layers.

2. The negative electrode according to claim 1, wherein the plurality of second metal layers are formed of a metal material less reactive than lithium metal.

3. Each of the plurality of second metal layers includes a first region that overlaps with the first metal layer and a second region that is a region other than the first region. The negative electrode according to claim 1 or 2, wherein at least one of the plurality of second metal layers is formed such that the length in the width direction of the first region is shorter than the length in the width direction of the second region.

4. The negative electrode according to claim 3, wherein at least one first region of the plurality of second metal layers is embedded in the first metal layer.

5. The negative electrode according to claim 3, wherein each of the first regions of the plurality of second metal layers has substantially the same widthwise length from one another.

6. The negative electrode according to claim 3, comprising a negative electrode tab formed in at least one second region of the plurality of second metal layers.

7. The negative electrode according to claim 6, wherein at least one of the plurality of second metal layers includes a margin region which is a region other than the region corresponding to the negative electrode tab.

8. Multiple first metal layers formed of lithium metal, A second metal layer is formed from a material other than lithium metal, and includes a first region that overlaps with at least one of the plurality of first metal layers and a second region that is a region other than the first region, and is interposed between the plurality of first metal layers and bonded to the plurality of first metal layers. A negative electrode comprising a margin region provided adjacent to at least one of the plurality of first metal layers in the second region.

9. The negative electrode according to claim 8, wherein the second metal layer is formed of a metal material that is less reactive than lithium metal.

10. The negative electrode according to claim 8, further comprising a negative electrode tab formed in the second region.

11. The negative electrode according to claim 10, wherein, when viewed from the thickness direction of one of the first metal layers, at least a portion of the margin region is provided between the negative electrode tab and one of the first metal layers, or between the negative electrode tab and the first region.

12. The negative electrode according to claim 8, wherein at least a portion of the first region includes one or more of a predetermined pattern structure and a surface-treated region.

13. The length in the width direction of the first region is formed to be shorter than the length in the width direction of the second region, the negative electrode according to claim 8.

14. It includes a first metal layer and a second metal layer that overlaps and is bonded to a portion of one side edge of the first metal layer. The second metal layer includes a first region that overlaps with the first metal layer and a second region that is a region other than the first region. A negative electrode sheet having a negative electrode tab formed in the second region, including a first tab, a second tab, and a third tab, wherein the second and third tabs, which are mutually adjacent on both sides with respect to the first tab, are each positioned at a predetermined distance from the first tab, and the first length, which is the distance between the first and second tabs, is formed to be longer than the second length between the first and third tabs.

15. The negative electrode sheet according to claim 14, wherein the second metal layer is formed of a metal material that is less reactive than the first metal layer.

16. It includes a positive electrode, a negative electrode, and a separation membrane, The negative electrode includes a first metal layer made of lithium metal and a second metal layer that overlaps and is bonded to a portion of one side edge of the first metal layer, wherein the second metal layer is made of a metal material less reactive than lithium metal and is interposed between the two separation membranes to form the negative electrode structure. The negative electrode structure includes a stacking portion and a folding portion, An electrode assembly having a structure in which the stack portion and the positive electrode are alternately stacked in sequence.

17. The electrode assembly according to claim 16, wherein the stack portion and the folding portion are each provided in multiple units.

18. The electrode assembly according to claim 16, wherein the negative electrode includes a plurality of second metal layers, and the first metal layer is interposed between the plurality of second metal layers.

19. The electrode assembly according to claim 16, wherein the negative electrode comprises a plurality of first metal layers, and the second metal layer is interposed between the plurality of first metal layers.

20. The positive electrode includes a positive electrode active material layer containing a positive electrode active material and a positive electrode current collector supporting the positive electrode active material layer. The electrode assembly according to claim 16, wherein the positive electrode active material contains a sulfur compound.

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