Electrode assembly, cylindrical battery cell and battery pack comprising battery cell

Abstract

An electrode assembly includes a first electrode plate, a second electrode plate, and a separator interposed between the first electrode plate and the second electrode plate, in which a first side of the first electrode plate and a first side of the second electrode plate are arranged in opposite directions, a first side of the separator protruding beyond a second side of the first electrode plate, and a second side of the separator protruding beyond the second side of the second electrode plate. And a separator protruding from the first side of the first electrode plate and disposed on the electrode active material portion of the second electrode plate, and a second side of the separator protruding beyond the second side of the second electrode plate and disposed on the uncoated portion of the first electrode plate. According to one aspect of the present invention, uncoated portions protruding from the top and bottom of the electrode assembly can be used as electrode tabs to reduce the internal resistance of the battery cell and increase the energy density. According to another aspect of the present invention, a structure of an uncoated portion of an electrode assembly is improved to prevent interference, particularly interference between an uncoated portion of an electrode plate and a separator, during formation of a hemming portion of a battery can, thereby reducing melting and damage of the separator when bending and welding the uncoated portion.

Description

Technical Field

[0001] This application claims priority to Korean Patent Application No. 10-2022-0183529, filed in Korea on December 23, 2022, the disclosure of which is incorporated herein by reference. The present disclosure relates to an electrode assembly, a cylindrical battery cell, a battery pack, and a vehicle including the battery pack. Background Art

[0002] Since secondary batteries are easily applicable to different types of products and have electrical characteristics such as high energy density, they are generally applied not only to portable devices but also to electric vehicles (EVs) or hybrid electric vehicles (HEVs) powered by a power source.

[0003] Secondary batteries significantly reduce the use of fossil fuels, and in addition to the main advantages, they do not generate by-products due to energy use. From this perspective, secondary batteries are regarded as a new energy source with eco-friendliness and improved energy efficiency.

[0004] Currently widely used types of secondary batteries include lithium-ion batteries, lithium polymer batteries, nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, etc. A single secondary battery cell or a single battery cell has an operating voltage of about 2.5 V to 4.5 V. Therefore, when a higher output voltage is required, a plurality of battery cells may be connected in series to form a battery pack. In addition, a battery pack may be formed by connecting a plurality of battery cells in parallel according to the charge / discharge capacity required for the battery pack. Therefore, the number and electrical connection type of the battery cells included in the battery pack may be set differently according to the required output voltage and / or charge / discharge capacity.

[0005] In addition, cylindrical, square, and pouch-type battery cells are referred to as types of single secondary battery cells. For example, a cylindrical battery cell is manufactured by winding a positive electrode and a negative electrode with a separator or insulator interposed therebetween to form a wound-core type electrode assembly and placing the electrode assembly in a battery can. In addition, uncoated portions of each of the positive electrode and the negative electrode may be connected to bar-type electrode connectors, and the electrode connectors electrically connect the electrode assembly to exposed electrode terminals. For reference, the positive electrode terminal is a cover plate of a sealing body that seals an opening portion of the battery can, and the negative electrode terminal is the battery can. A conventional cylindrical battery cell having such a structure has a high resistance and a low current collection efficiency, and generates a large amount of heat due to current concentration on the bar-type electrode connectors connected to the uncoated portion of the positive electrode and / or the uncoated portion of the negative electrode.

[0006] Resistance and heat generation issues are not critical for small cylindrical battery cells with 18650 or 21700 form factors. However, as the form factor of cylindrical battery cells applied to electric vehicles increases, a large amount of heat may be generated near the electrode joints during rapid charging, leading to fires in the cylindrical battery cells.

[0007] To solve this problem, a cylindrical battery cell (so-called jointless cylindrical battery cell) having a structure for improved current collection efficiency has been proposed by designing such that the uncoated portion of the positive electrode and the uncoated portion of the negative electrode are located at the upper and lower ends of the wound-core type electrode assembly, respectively, and welding the current collector plates to the uncoated portions.

[0008] Figures 1 to 3 is a diagram showing the process of manufacturing a jointless cylindrical battery cell. Figure 1 shows the structure of the electrode plates, Figure 2 shows the process of winding the electrode plates, and Figure 3 shows the process of welding the current collector plates to the bent surfaces of the uncoated portions.

[0009] Referring to Figures 1 to 3 , the first electrode plate 10 and the second electrode plate 11 have a structure in which the active material 21 is coated on the sheet-like current collector 20, and the uncoated portion 22 exists on the long sides along the length direction X.

[0010] As Figure 2 shown, the electrode assembly A is manufactured by sequentially stacking the first electrode plate 10 and the second electrode plate 11 together with two sheets of separator 12 and winding them along the length direction X. In this case, the uncoated portions of the first electrode plate 10 and the second electrode plate 11 are arranged in opposite directions.

[0011] After the winding process, the uncoated portion 10a of the first electrode plate 10 and the uncoated portion 11a of the second electrode plate 11 are bent toward the core. Subsequently, the current collector plates 30, 31 are connected to the uncoated portions 10a, 11a by welding, respectively.

[0012] No electrode joints are connected to the uncoated portion 10a of the positive electrode and the uncoated portion 11a of the negative electrode, and the current collector plates 30, 31 are connected to the external electrode terminals. Since the current path is formed along the winding axis direction Y' (see arrow) of the electrode assembly A with a large cross-sectional area, the resistance of the battery cell is reduced. This is because the resistance is inversely proportional to the cross-sectional area of the channel through which the current flows.

[0013] In the jointless cylindrical battery cell, in order to improve the welding characteristics of the uncoated portions 10a, 11a and the current collector plates 30, 31, it is necessary to bend the uncoated portions 10a, 11a as flat as possible by applying a strong pressure to the welding positions of the uncoated portions 10a, 11a.

[0014] However, when the welding positions of the uncoated portions 10a and 11a are bent, the uncoated portions 10a and 11a may be deformed into irregular shapes. In this case, when the deformed portions come into contact with the electrode plates of the opposite polarity, internal short circuits or microcracks may occur in the uncoated portions 10a and 11a. In addition, when the uncoated portion 32 adjacent to the core of the electrode assembly A is bent, all or most of the cavity 33 at the core of the electrode assembly A is blocked. In this case, problems occur during the electrolyte solution injection process. That is, the cavity 33 at the core of the electrode assembly A serves as a channel for injecting the electrolyte solution. However, when the corresponding channel is blocked, it is difficult to inject the electrolyte solution. In addition, during the process of inserting the electrolyte injector into the cavity 33, the uncoated portion 32 may be torn due to interference between the electrolyte injector and the uncoated portion 32 near the core.

[0015] In addition, the bent portions of the uncoated portions 10a and 11a to which the current collectors 30 and 31 are welded should be overlapped in multiple layers without blank spaces (gaps) in order to obtain sufficient welding strength and prevent ablation of the separator or the active material due to laser penetration into the electrode assembly A when using state-of-the-art technologies such as laser welding.

[0016] In addition, the conventional jointless cylindrical battery cell has the positive electrode uncoated portion 10a over the entire upper region of the electrode assembly A. Therefore, when the curled edge portion is formed by curling the outer peripheral surface at the upper end of the battery can, the upper edge region 34 of the electrode assembly A is squeezed by the battery can. This squeezing may cause local deformation of the electrode assembly A, and in this case, the separator 12 may be torn, resulting in an internal short circuit. When a short circuit occurs in the battery, the battery may generate heat or explode.

[0017] In addition, in the case of a non-notch wound core, after assembly, the current collector foil is folded to form an internal and external closed structure, which hinders the movement of the electrolyte solution towards the electrodes inside the wound core during the electrolyte solution injection process, resulting in non-uniform electrolyte wetting characteristics. It is caused by non-uniform electrolyte wetting paths when injecting the electrolyte solution. Therefore, the low wetting uniformity increases the non-uniformity in the battery, leading to an unstable solid electrolyte interface (SEI) layer and increased resistance variation.

[0018] In addition, in existing electrode assemblies, the positive electrode has a smaller area than the negative electrode (particularly the area of the electrode active material portion), and particularly in the width direction, the separator covers all of the electrode active material portions of the first electrode plate and the electrode active material portion of the second electrode plate. In this case, when the lower end portion of the electrode assembly is flattened by bending the uncoated portions of each electrode plate, the bent uncoated portions may contact the ends of the separator, and the separator may melt due to the heat applied during welding of the uncoated portions, resulting in damage. Summary of the Invention

[0019] Technical Problem

[0020] The present disclosure is designed in the above background, and thus the present disclosure relates to providing an electrode assembly having improved electrolyte wetting characteristics.

[0021] The present disclosure also relates to providing an electrode assembly having an improved uncoated portion structure to reduce the stress applied to the uncoated portions exposed at both ends of the electrode assembly when the uncoated portions are bent.

[0022] The present disclosure also relates to providing an electrode assembly in which an electrolyte solution injection channel is not blocked when the uncoated portion is bent.

[0023] The present disclosure also relates to providing an electrode assembly including a structure for preventing contact between the upper edge of the electrode assembly and the inner surface of the battery can when the upper end of the battery can is curled.

[0024] The present disclosure also relates to providing an electrode assembly having a higher energy density and a lower resistance.

[0025] The present disclosure also relates to providing a cylindrical battery cell including an electrode assembly having an improved structure, a battery pack including the cylindrical battery cell, and a vehicle including the battery pack.

[0026] However, the technical problems to be solved by the present disclosure are not limited to the above problems, and those skilled in the art will clearly understand these and other problems from the following description.

[0027] Technical Solution

[0028] The present disclosure relates to an electrode assembly for an electrochemical device. A first aspect of the present disclosure relates to an electrode assembly, and the electrode assembly includes a first electrode plate, a second electrode plate, and a separator between the first electrode plate and the second electrode plate, wherein the first electrode plate is a positive electrode plate and the second electrode plate is a negative electrode plate, or the first electrode plate is a negative electrode plate and the second electrode plate is a positive electrode plate.

[0029] Among them, each of the first electrode plate, the second electrode plate, and the separator independently has a strip shape with an aspect ratio greater than 1, and the first electrode plate, the second electrode plate, and the separator are stacked such that their respective length directions are parallel to each other.

[0030] Among them, each of the first electrode plate, the second electrode plate, and the separator independently has a first side and a second side. Among them, the first side is the first end in the thickness direction, and the second side is the second end disposed at a position opposite to the first side.

[0031] Among them, the first electrode plate and the second electrode plate include a first portion and a second portion on at least one side surface. The first portion is an electrode active material portion coated with an electrode active material and extends from the second side toward the first side, and the second portion is an uncoated portion not coated with an electrode active material and extends from the first side toward the second side to the electrode active material portion.

[0032] Among them, in the electrode assembly, the first sides of the first electrode plate and the second electrode plate are arranged facing opposite directions.

[0033] And among them, in the electrode assembly, the first side of the separator protrudes beyond the second side of the first electrode plate and is disposed on the electrode active material portion of the second electrode plate, and the second side of the separator protrudes beyond the second side of the second electrode plate and is disposed on the uncoated portion of the first electrode plate. In a specific embodiment of the present disclosure, the second electrode plate is a negative electrode plate, and the first electrode plate is a positive electrode plate.

[0034] According to a second aspect of the present disclosure, in the first aspect, based on the width direction, the width of the electrode active material portion of the first electrode plate is narrower than the width of the electrode active material portion of the second electrode plate, and both ends of the electrode active material portion of the first electrode plate in the width direction are disposed between both ends of the electrode active material portion of the second electrode plate in the width direction.

[0035] According to a third aspect of the present disclosure, in the first aspect or the second aspect, at least a part of the uncoated portion of at least one of the first electrode plate and the second electrode plate is divided into a plurality of segments by a cutting groove with a predetermined depth.

[0036] According to a fourth aspect of the present disclosure, in the third aspect, each of the plurality of segments has a square or rectangular, trapezoidal, triangular, parallelogram, semi-circular or semi-ovoid or semi-elliptical structure.

[0037] According to a fifth aspect of the present disclosure, in the fourth aspect, the first electrode plate has first electrode plate segments, and wherein the separator is arranged to cover the slotted valleys of the cutting grooves of the segments.

[0038] According to a sixth aspect of the present disclosure, in any one of the first to fifth aspects, the electrode assembly has a plurality of winding turns by winding the first electrode plate, the second electrode plate, and the separator around an axis in the length direction.

[0039] According to a seventh aspect of the present disclosure, in the fifth aspect, the electrode assembly has a plurality of winding turns by winding the first electrode plate, the second electrode plate, and the separator around an axis in the length direction,

[0040] and wherein all or at least some of the segments are bent radially with respect to the axis at a bending point, where the bending point is any point within the segment.

[0041] According to an eighth aspect of the present disclosure, in the seventh aspect, the second side of the separator is disposed on the uncoated portion of the first electrode plate and is interposed between the electrode active material portion and the bending point.

[0042] According to a ninth aspect of the present disclosure, in the eighth aspect, the bending point is spaced apart from the second side of the separator by 0.1 mm or more.

[0043] According to a tenth aspect of the present disclosure, in any one of the first to ninth aspects, the uncoated portion of at least one of the first electrode plate and the second electrode plate includes a core-side uncoated portion adjacent to the core of the electrode assembly, an outer-periphery-side uncoated portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate uncoated portion between the core-side uncoated portion and the outer-periphery-side uncoated portion,

[0044] wherein at least one of the core-side uncoated portion and the outer-periphery-side uncoated portion has a shorter distance from the electrode active material portion to the first side than the intermediate uncoated portion,

[0045] and wherein the electrode active material portion has a constant width from the core side to the outer-periphery side with reference to the thickness direction.

[0046] According to an eleventh aspect of the present disclosure, in any one of the first to tenth aspects, the uncoated portion of at least one of the first electrode plate and the second electrode plate includes a core-side uncoated portion adjacent to the core of the electrode assembly, an outer-periphery-side uncoated portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate uncoated portion between the core-side uncoated portion and the outer-periphery-side uncoated portion,

[0047] Among them, the uncoated part on the core side has a shorter distance from the electrode active material part to the first side than the uncoated part in the middle and the uncoated part on the outer peripheral side, and among them, the electrode active material part has a constant width in the thickness direction from the core side to the outer peripheral side.

[0048] According to the twelfth aspect of the present disclosure, in the tenth or eleventh aspect, the uncoated part on the core side includes the uncoated part of the electrode plate part corresponding to the innermost wound turn of the electrode assembly, and the uncoated part on the outer peripheral side includes the uncoated part of the electrode plate part corresponding to the outermost wound turn of the electrode assembly.

[0049] According to the thirteenth aspect of the present disclosure, in the eleventh or twelfth aspect, all or at least a part of the uncoated part in the middle is divided into a plurality of segments.

[0050] According to the fourteenth aspect of the present disclosure, in the tenth or eleventh aspect, at least a part of the uncoated part in the middle has a height that gradually increases in the winding axis direction from the core side toward the outer peripheral side.

[0051] According to the fifteenth aspect of the present disclosure, in the thirteenth or fourteenth aspect, at least a part of the uncoated part in the middle has a height that gradually increases in the winding axis direction from the core side toward the outer peripheral side.

[0052] According to the sixteenth aspect of the present disclosure, in any one of the third to fifteenth aspects, the slotted valley of each segment and the electrode active material part are spaced apart from each other by a predetermined distance.

[0053] According to the seventeenth aspect of the present disclosure, in any one of the first to sixteenth aspects, the separator includes a porous polymer substrate; and a porous coating on at least one surface of the porous polymer substrate, and the porous coating includes inorganic particles and a binder polymer.

[0054] According to the eighteenth aspect of the present disclosure, in the seventeenth aspect, the inorganic particles include inorganic particles having hydrophilicity on the surface.

[0055] The nineteenth aspect of the present disclosure relates to a cylindrical battery cell, and the cylindrical battery cell includes an electrode assembly according to any one of the first to eighteenth aspects;

[0056] A battery can that houses the electrode assembly and is electrically connected to one of the first electrode plate and the second electrode plate, and the battery can is of the first polarity; a sealing body that seals the open end of the battery can; and a terminal that is electrically connected to the other of the first electrode plate and the second electrode plate and has an exposed surface, and the terminal is of the second polarity.

[0057] The twentieth aspect of the present disclosure relates to a battery pack, and the battery pack includes a cylindrical battery cell according to the nineteenth aspect.

[0058] Advantageous Effects

[0059] According to one aspect of the present disclosure, using the uncoated portions protruding at the upper and lower portions of the electrode assembly as electrode joints can reduce the internal resistance of the battery cell and increase the energy density.

[0060] According to another aspect of the present disclosure, the improved uncoated portion structure of the electrode assembly can prevent interference between the uncoated portion of the electrode plate and the separator during the process of forming the curled portion of the battery can, thereby reducing melting and damage of the separator during bending and welding of the uncoated portion.

[0061] According to another aspect of the present disclosure, the improved uncoated portion structure of the electrode assembly can prevent the uncoated portion from tearing when bending the uncoated portion, and sufficiently increase the number of overlapping layers of the uncoated portion, thereby resulting in improved welding strength. In addition, when forming a cutting groove in the uncoated portion of the electrode plate, the grooved valley can be formed as deep as possible (i.e., minimizing the distance between the grooved valley and the electrode active material portion), thereby achieving deeper grooving.

[0062] According to another aspect of the present disclosure, the improved uncoated portion structure adjacent to the core of the electrode assembly can prevent the cavity at the core of the electrode assembly from being blocked when bending the uncoated portion, making it easy to perform the electrolyte solution injection process and the welding process of the battery can and the current collector plate.

[0063] According to another aspect of the present disclosure, a cylindrical battery cell having a structure for achieving low internal resistance, preventing internal short circuit, and improving the welding strength of the current collector plate and the uncoated portion can be provided, as well as a battery pack and a vehicle including the cylindrical battery cell.

[0064] In addition, the present disclosure can have many other effects, and the effects will be described in each embodiment, or the corresponding description will be omitted regarding the effects that can be easily inferred by those skilled in the art. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] The drawings illustrate exemplary embodiments of the present disclosure and are used together with the following detailed description to provide a further understanding of the technical aspects of the present disclosure, and thus the present disclosure should not be construed as being limited to the drawings.

[0066] Figure 1 is a plan view showing the structure of an electrode plate for manufacturing a conventional jointless cylindrical battery cell.

[0067] Figure 2 is a view showing the process of winding an electrode plate of a conventional jointless cylindrical battery cell.

[0068] Figure 3 Shows the process of welding a current collector plate to the bent surface of an uncoated portion in a conventional jointless cylindrical battery cell.

[0069] Figure 4 Is a plan view showing the structure of an electrode plate according to a first embodiment of the present disclosure.

[0070] Figure 5 Is a plan view showing the structure of an electrode plate according to a second embodiment of the present disclosure.

[0071] Figure 6 Is a plan view showing the structure of an electrode plate according to a third embodiment of the present disclosure.

[0072] Figure 7a Is a plan view showing the structure of an electrode plate according to a fourth embodiment of the present disclosure, Figure 7b Is a plan view showing the structure of an electrode plate according to a fifth embodiment of the present disclosure.

[0073] Figure 7c Is an enlarged sectional view in segments.

[0074] Figure 8 Shows a cross-section of an electrode assembly illustrating a conventional stacking structure.

[0075] Figure 9a And Figure 9b Shows a cross-section of an electrode assembly illustrating a stacking structure according to the present disclosure.

[0076] Figure 10a And Figure 10b Shows the definition of the width, height, and pitch of segments according to an embodiment of the present disclosure.

[0077] ​ Is a cross-sectional view of a wound-core type electrode assembly including a first electrode plate (positive electrode plate) and a second electrode plate (negative electrode plate) using the electrode plate of the first embodiment, taken along the Y-axis direction (winding axis direction).

[0078] ​ Is a cross-sectional view of a wound-core type electrode assembly including a first electrode plate (positive electrode plate) and a second electrode plate (negative electrode plate) using the electrode plate of the second embodiment, taken along the Y-axis direction (winding axis direction).

[0079] ​ Is a cross-sectional view of a wound-core type electrode assembly including a first electrode plate (positive electrode plate) and a second electrode plate (negative electrode plate) using any one of the electrode plates of the third to fifth embodiments (their variants), taken along the Y-axis direction (winding axis direction).

[0080] ​ It is a cross-sectional view taken along the Y-axis direction (winding axis direction) of an electrode assembly according to another embodiment of the present disclosure.

[0081] ​ It is a cross-sectional view taken along the Y-axis direction (winding axis direction) of an electrode assembly according to another embodiment of the present disclosure.

[0082] ​ It is a cross-sectional view taken along the Y-axis direction (winding axis direction) of an electrode assembly according to another embodiment of the present disclosure.

[0083] ​ It is a cross-sectional view taken along the Y-axis direction of a cylindrical battery cell according to an embodiment of the present disclosure.

[0084] ​ It is a cross-sectional view taken along the Y-axis direction of a cylindrical battery cell according to another embodiment of the present disclosure.

[0085] ​ It is a cross-sectional view taken along the Y-axis direction of a cylindrical battery cell according to another embodiment of the present disclosure.

[0086] ​ It is a cross-sectional view taken along the Y-axis direction of a cylindrical battery cell according to another embodiment of the present disclosure.

[0087] ​ It is a cross-sectional view taken along the Y-axis direction of a cylindrical battery cell according to another embodiment of the present disclosure.

[0088] ​ It is a cross-sectional view taken along the Y-axis direction of a cylindrical battery cell according to another embodiment of the present disclosure.

[0089] ​ It is a cross-sectional view taken along the Y-axis direction of a cylindrical battery cell according to another embodiment of the present disclosure.

[0090] ​ It is a cross-sectional view taken along the Y-axis direction of a cylindrical battery cell according to another embodiment of the present disclosure.

[0091] ​ It is a cross-sectional view taken along the Y-axis direction of a cylindrical battery cell according to another embodiment of the present disclosure.

[0092] ​ It is a diagram schematically showing the configuration of a battery pack according to an embodiment of the present disclosure.

[0093] ​FIG. is a diagram schematically showing a vehicle including a battery pack according to an embodiment of the present disclosure.

[0094] ​ Capacity retention characteristics according to an example and a comparative example are shown.

[0095] ​ Photographic images of an electrode assembly according to the present disclosure before and after winding are shown.

[0096] ​ Collection positions of each electrolyte-filled sample in an example and a comparative example are shown. DETAILED DESCRIPTION

[0097] Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Before the description, it should be understood that terms or words used in the specification and the appended claims should not be construed as limited to general and dictionary meanings, but should be interpreted based on meanings and concepts corresponding to technical aspects of the present disclosure on the basis of the principle that allows the inventor to appropriately define terms for the best interpretation.

[0098] Therefore, the embodiments described herein and the illustrations shown in the drawings are exemplary embodiments for describing technical aspects of the present disclosure and are not intended to be restrictive. Thus, it should be understood that various other equivalents and modifications can be made thereto when this application is filed.

[0099] In addition, to assist in understanding the present disclosure, some elements may be shown in the drawings in an enlarged size rather than an actual scale. In addition, the same elements in different embodiments may be given the same reference numerals.

[0100] (Definition)

[0101] For ease of description, in this specification, a sheet-like structure such as a first electrode plate, a second electrode plate, and a separator, or an electrode assembly including stacked first electrode plate, second electrode plate, and separator is in a strip shape with an aspect ratio greater than 1. Here, the direction based on the longer side of the horizontal side and the vertical side is called the length direction X, and the direction perpendicular to the length direction (i.e., the direction based on the shorter side) is called the width direction Y. In addition, the electrode assembly can be wound into a core shape, and the direction of the length direction along the winding axis of the electrode assembly is called the axial direction Y'. The axial direction can be the same as the width direction. In addition, the direction around the winding axis is called the circumferential direction X'. The circumferential direction can be the same as the length direction. In addition, the direction facing the winding axis or the direction away from the winding axis is called the radial direction Z. In particular, the direction facing the winding axis is called the centripetal direction, and the direction away from the winding axis is called the centrifugal direction.

[0102] First, the structure of the electrode assembly according to an embodiment of the present disclosure will be described.

[0103] The electrode assembly includes a first electrode plate, a second electrode plate, and a separator between the first electrode plate and the second electrode plate. In the present disclosure, each of the first electrode plate, the second electrode plate, and the separator independently has a strip shape with an aspect ratio greater than 1. In the electrode assembly, the first electrode plate, the second electrode plate, and the separator may be stacked such that their length directions are parallel to each other.

[0104] The first electrode plate and the second electrode plate include a current collector such as a conductive foil, and an electrode active material portion with a predetermined thickness at a second portion on at least one surface of the current collector. In an embodiment of the present disclosure, the first electrode plate may be a positive electrode plate, and the second electrode plate may be a negative electrode plate. Conversely, the first electrode plate may be a negative electrode plate, and the second electrode plate may be a positive electrode plate. In a specific embodiment of the present disclosure, the first electrode plate may be a positive electrode plate, and the second electrode plate may be a negative electrode plate.

[0105] Each of the first electrode plate, the second electrode plate, and the separator independently has a first side as one end in the width direction and a second side as the other end opposite to the first side. The sides that are the ends of the first electrode plate and the second electrode plate in the width direction correspond to the first side and the second side, respectively. In the first electrode plate and the second electrode plate, the first side is included in the uncoated portion of each electrode plate, and the second side is included in the electrode active material portion of each electrode plate. The first side and the second side are arranged on opposite sides in the width direction Y.

[0106] Each electrode plate includes a first portion and a second portion on at least one surface. The first portion is a coated electrode active material portion and extends from the second side toward the first side. In an embodiment of the present disclosure, in each electrode plate, the electrode active material portion may have a constant width along the length direction X. The second portion is an uncoated portion without an electrode active material portion and extends from the first side toward the second side to the electrode active material portion. As described below, in each electrode plate, the uncoated portion may not have a constant width along the length direction. That is, the distance from the boundary Bou between the electrode active material portion and the uncoated portion to the second side may not be constant. Each electrode plate may independently have electrode active material portions on two surfaces, and when the electrode active material portions are present on two surfaces, the electrode active material portions on the front surface and the back surface are arranged at facing positions. That is, in each electrode plate, the uncoated portion does not have an electrode active material portion on both surfaces of the current collector. The uncoated portion itself may be set as an electrode terminal or may be divided into segments as described below, and the segments may be set as electrode terminals.

[0107] In addition, in the electrode assembly, the first sides of the first electrode plate and the second electrode plate are arranged to face opposite directions (see ​ and ​ ).

[0108] In addition, in the electrode assembly, based on the width direction, the width of the electrode active material portion of the first electrode plate is narrower than the width of the electrode active material portion of the second electrode plate, and both ends of the electrode active material portion of the first electrode plate in the width direction are provided between both ends of the electrode active material portion of the second electrode plate in the width direction (see ​ and ​ ).

[0109] In the electrode assembly, the first side of the separator extends beyond the second side of the first electrode plate and is disposed on the electrode active material portion of the second electrode plate. In addition, the second side of the separator extends beyond the second side of the second electrode plate and is disposed on the uncoated portion of the first electrode plate (see ​ and ​ ).

[0110] In a specific embodiment of the present disclosure, the second electrode plate is preferably a negative electrode plate. When designing the battery, considering the NP ratio, the capacity of the positive electrode is high, and in order to ensure the capacity of the positive electrode, it is necessary to design such that the size (width) of the negative electrode is larger than the size (width) of the positive electrode. In order to improve the wetting performance of the electrode assembly by exposing a predetermined portion of the negative electrode active material portion of the negative electrode plate without directly contacting the positive electrode and the negative electrode, the surface of the electrode active material portion of the positive electrode plate can be completely covered by the separator, and a part of the surface of the electrode active material portion of the negative electrode plate can be exposed. In addition, the width of the electrode active material portion of the positive electrode plate can be narrower than the width of the electrode active material portion of the negative electrode plate, and based on the width, the positive electrode active material portion can be arranged so as not to deviate from the negative electrode active material portion.

[0111] In addition, in an embodiment of the present disclosure, at least a part of the uncoated portion of at least one of the first electrode plate and the second electrode plate is divided into a plurality of segments by cutting grooves with a predetermined depth. For example, the uncoated portion of the positive electrode may have a plurality of segments on all or at least a part of the second side. At the same time or independently thereof, the uncoated portion of the negative electrode may have a plurality of segments on all or at least a part of the second side. Each of the plurality of segments may have a square or rectangular, trapezoidal, triangular, parallelogram, semi-circular or semi-ovoid or semi-elliptical structure.

[0112] ​ is a plan view showing the structure of the electrode plate 40 according to the first embodiment of the present disclosure. The electrode plate can be applied to the first electrode plate or the second electrode plate or both.

[0113] Reference ​ , the second side is the side formed along the lowermost end portion of the electrode active material portion 42 in the winding axis direction Y, and the first side is the side formed along the uppermost end portion of the uncoated portion 43 in the winding axis direction Y.

[0114] Each electrode plate independently includes an electrode active material portion or a first portion on at least one surface or both surfaces. The first portion extends a predetermined length from the second side toward the first side. ​ The shape of the electrode plate before winding the electrode assembly is shown. Reference ​ , the electrode active material portion may have a constant width over the entire length of the electrode plate in the axial direction from the second side to the starting point of the uncoated portion.

[0115] Reference ​ , the electrode plate according to an embodiment of the present disclosure is the second electrode plate or the first electrode plate or both. The electrode plate 40 includes a current collector 41 formed of a metal foil and an electrode active material portion 42. The metal foil may be aluminum or copper and is appropriately selected according to the polarity of the electrode plate 40. The electrode active material portion is formed on at least one surface of the current collector 41, and the uncoated portion 43 is provided at an end of the long side of the current collector in the length direction X. The uncoated portion 43 is a portion where the electrode active material is not coated.

[0116] In an embodiment of the present disclosure, an insulating coating 44 may be formed at the boundary between the electrode active material portion 42 and the uncoated portion 43. At least a part of the insulating coating 44 overlaps the boundary between the electrode active material portion 42 and the uncoated portion 43. The insulating coating 44 may include a polymer resin and / or an inorganic substance such as Al2O3.

[0117] In an embodiment of the present disclosure, the uncoated portion 43 includes a core-side uncoated portion B1 adjacent to the core of the electrode assembly, an outer-periphery-side uncoated portion B3 adjacent to the outer periphery of the electrode assembly, and an intermediate uncoated portion B2 between the core-side uncoated portion B1 and the outer-periphery-side uncoated portion B3.

[0118] When each electrode plate 40 is wound into a core-type electrode assembly, the uncoated portion B1 on the core side, the uncoated portion B3 on the outer peripheral side, and the uncoated portion B2 in the middle can be defined as the uncoated portion of the area adjacent to the core, the uncoated portion of the area adjacent to the outer periphery, and the uncoated portion of the remaining area other than them, respectively. The B1 / B2 boundary can be appropriately defined as the point where the height (or varying pattern) of the uncoated portion substantially changes from the core of the electrode assembly toward the outer periphery or the point based on a predetermined percentage of the radius of the electrode assembly (e.g., 5%, 10%, 15% of the radius). The B2 / B3 boundary can be defined as the point where the height (or varying pattern) of the uncoated portion substantially changes from the outer periphery of the electrode assembly toward the core or the point based on a predetermined percentage of the radius of the electrode assembly (e.g., 85%, 90%, 95% of the radius). When the B1 / B2 boundary and the B2 / B3 boundary are specified, the uncoated portion B2 in the middle can be automatically specified. When only the B1 / B2 boundary is specified, the B2 / B3 boundary can be appropriately selected from points near the outer periphery of the electrode assembly. Conversely, when only the B2 / B3 boundary is specified, the B1 / B2 boundary can be appropriately selected from points near the core of the electrode assembly. In the first embodiment, the height of the uncoated portion 43 is non-uniform and has a relative difference along the winding direction X'. That is, the height (length in the Y-axis direction) of the uncoated portion B3 on the outer peripheral side is smaller than the uncoated portion B1 on the core side and the uncoated portion B2 in the middle. In the embodiments of the present disclosure, in the electrode plate according to the first embodiment, at least a part of the uncoated portion can be divided into a plurality of segments by a cutting groove (not shown) with a predetermined depth.

[0119] ​ is a plan view showing the structure of an electrode plate 45 according to a second embodiment of the present disclosure.

[0120] Referring to ​ , the electrode plate 45 of the second embodiment has substantially the same configuration as the first embodiment, except that the height of the uncoated portion B3 on the outer peripheral side gradually decreases toward the outer periphery. In a variant, the uncoated portion B3 on the outer peripheral side can be changed to a stepped shape with a gradually decreasing height (see the dashed line). In the embodiments of the present disclosure, in the electrode plate according to the second embodiment, at least a part of the uncoated portion can be divided into a plurality of segments by a cutting groove (not shown) with a predetermined depth.

[0121] ​ is a plan view showing the structure of an electrode plate 50 according to a third embodiment of the present disclosure. Referring to ​, the electrode plate 50 of the third embodiment has a core-side uncoated portion B1 and a peripheral-side uncoated portion B3 with heights less than that of the middle uncoated portion B2. Additionally, the heights of the core-side uncoated portion B1 and the peripheral-side uncoated portion B3 may be equal or different. Preferably, the height of the middle uncoated portion B2 may have a stepped shape that gradually increases from the core towards the periphery.

[0122] Patterns 1 to 7 are divisions of the middle uncoated portion B2 based on the positions where the height of the uncoated portion 43 changes. Preferably, the number of patterns, as well as the height (length in the Y direction) and width (length in the X direction) of each pattern, can be adjusted to dissipate stress as much as possible during the bending of the uncoated portion 43. Stress dissipation is to prevent the uncoated portion 43 from tearing.

[0123] The width d of the core-side uncoated portion B1 is designed on the condition that the cavity at the core of the electrode assembly is not blocked when the pattern of the middle uncoated portion B2 bends towards the core. B1 。

[0124] In the electrode plate according to the third embodiment, at least a part of the uncoated portion can be divided into multiple segments by a cutting groove (not shown) with a predetermined depth.

[0125] In the example, the width d of the core-side uncoated portion B1 B1 can be increased proportionally to the height of the uncoated portion of Pattern 1 or the height of the segments of Pattern 1.

[0126] In a specific example, when the electrode plate 60 is used to manufacture an electrode assembly for a cylindrical battery cell with a 46800 form factor, according to the core diameter of the electrode assembly, the width d of the core-side uncoated portion B1 B1 can be set to 180 mm to 350 mm.

[0127] In the embodiment, the width of each pattern can be designed to form the same winding turn of the electrode assembly.

[0128] In a variant, the height of the middle uncoated portion B2 may have a stepped shape that increases from the core towards the periphery and then decreases.

[0129] In another variant, the peripheral-side uncoated portion B3 can be modified to have the same structure as that of the second embodiment.

[0130] In yet another variant, the pattern structure applied to the middle uncoated portion B2 can extend to the peripheral-side uncoated portion B3 (see the dashed line).

[0131] ​ is a plan view showing the structure of the electrode plate 60 according to the fourth embodiment of the present disclosure, and ​is a plan view showing the structure of the electrode plate 70 according to the fifth embodiment of the present disclosure. ​ and ​ is shown to be formed in segments over the entire area of the intermediate uncoated portion.

[0132] Referring to ​ , the electrode plate 60 of the fourth embodiment has a core-side uncoated portion B1 and an outer-periphery-side uncoated portion B3 with a height less than that of the intermediate uncoated portion B2. Additionally, the height of the core-side uncoated portion B1 and the height of the outer-periphery-side uncoated portion B3 may be equal or different.

[0133] Preferably, at least a part of the intermediate uncoated portion B2 may include a plurality of segments 61. The height of the plurality of segments 61 may gradually increase from the core to the outer periphery.

[0134] The segments 61 may be formed by laser grooving. The segments 61 may be formed by known metal foil cutting processes such as ultrasonic cutting or stamping.

[0135] In the fourth embodiment, a predetermined gap preferably exists between the grooved valleys of the segments 61 and the electrode active material portion 42 to prevent damage to the active material portion 42 and / or the insulating coating 44 during bending of the uncoated portion 43. This is because when the uncoated portion 43 is bent, stress concentrates at the lower end of the cutting line. The gap is preferably from 0.2 mm to 4 mm. When the gap is adjusted to the corresponding numerical range, damage to the active material portion 42 and / or the insulating coating 44 near the lower end of the cutting line due to stress can be prevented during bending of the uncoated portion 43. Additionally, the gap can prevent damage to the active material portion 42 and / or the insulating coating 44 due to tolerances during grooving or cutting of the segments 61. Preferably, at least a part of the insulating coating 44 may be exposed to the outside of the separator when the electrode plate 40 is wound into the electrode assembly. In this case, the insulating coating 44 can support the grooved valleys during bending of the segments 61.

[0136] The gap between the grooved valleys of the segments and the electrode active material portion may preferably be 1.0 mm or more. This will be more effective when the corresponding electrode is a negative electrode.

[0137] The gap between the grooved valleys of the segments and the electrode active material portion may more preferably be 2.0 mm or more. This will be more effective when the corresponding electrode is a positive electrode.

[0138] When the gap is less than the above range, the above anti-damage effect cannot be fully exerted, and when the gap is greater than the above range, the anti-damage effect does not increase, and the capacity of the electrode decreases.

[0139] The boundary region between the uncoated portion where the electrode active material portion is not coated and the coated portion where the electrode active material portion is coated can be covered by an insulating layer, and in this case, a predetermined gap can exist between the segmented slotted valleys and the insulating layer. The gap can be from 0.2 mm to 1.5 mm.

[0140] When the gap is less than the above range, the above anti-damage effect cannot be fully exerted, and when the gap is greater than the above range, the anti-damage effect is not increased, and the segmented bending support effect of the insulating coating is reduced.

[0141] A plurality of segments 61 can form a plurality of segment groups from the core to the outer periphery. The widths, heights, and pitches of the segments in the same segment group can be substantially equal.

[0142] ​ is a plan view showing the structure of the electrode plate 70 according to the fifth embodiment of the present disclosure.

[0143] Referring to ​ , except that the shape of the segment 61' changes from a rectangle to a trapezoid, the electrode plate 70 of the fifth embodiment is basically the same as the fourth embodiment (or variant).

[0144] Subsequently, the electrode assembly according to the embodiments of the present disclosure will be described in more detail. ​ A cross-section of an electrode assembly showing a conventional stacked structure is shown. Referring to ​ , based on the width direction, the electrode active material portions of the first electrode and the second electrode are completely covered by the separator, and each of the two ends of the separator extends outward from the electrode active material portion.

[0145] ​ and ​ A cross-section of an electrode assembly showing the stacked structure according to the present disclosure is shown. Referring to ​ and ​ , the first side of the first electrode plate and the first side of the second electrode plate are arranged facing opposite directions, and based on the width direction, the width of the electrode active material portion of the first electrode plate is narrower than the width of the electrode active material portion of the second electrode plate. The two ends of the electrode active material portion of the first electrode plate in the width direction are provided between the two ends of the electrode active material portion of the second electrode plate in the width direction. As described above, in the present disclosure, preferably, the second electrode plate is a negative electrode plate, and the first electrode plate is a positive electrode plate.

[0146] In the electrode assembly, the first side of the separator extends beyond the second side of the first electrode plate and is provided on the electrode active material portion of the second electrode plate. In addition, the second side of the separator extends beyond the second side of the second electrode plate and is provided on the uncoated portion of the first electrode plate.

[0147] Subsequently, reference will be made to ​ and ​ to describe in more detail the position of the separator in the electrode assembly of the present disclosure.

[0148] Referring to ​ and ​ , a first side SP1 of the separator as an end portion extends outward from a second side of the first electrode plate E1 and is disposed on an electrode active material portion of the second electrode plate E2.

[0149] In an embodiment of the present disclosure, the distance L1 between the first side of the separator and the boundary Bou between the electrode active material portion and the uncoated portion of the second electrode plate can be at most about 3.0 mm. When the distance from the first side of the separator to the boundary Bou is greater than the above range, the width of the positive electrode active material portion is much smaller than that of the negative electrode active material portion, making it difficult to set an optimal NP ratio. In addition, the distance L1 can be 0.3 mm or more, 0.5 mm or more, or 1.0 mm or more. When the distance L1 is insufficient, due to the low exposure of the separator and the electrode active material portion of the second electrode plate (e.g., the negative electrode plate), the electrolyte wetting improvement effect cannot be fully exerted during the injection of the electrolyte solution.

[0150] In addition, the distance L2 between the second side of the first electrode plate and the first side of the separator is preferably at least 1.0 mm. For example, the distance L2 can be 1.2 mm or more, 1.5 mm or more, 2.0 mm or more, or 2.5 mm or more. When the distance is too short, the separator may not be able to sufficiently insulate the positive electrode from the negative electrode. In addition, the distance L2 is not limited to a specific range, but can be 5.0 mm or less, or 4.5 mm or less, or 4.0 mm or less, or 3.5 mm or less, or 3.0 mm or less, or 2.5 mm or less, or 2.0 mm or less. When L2 is too large, the NP ratio may not be properly designed, and due to the too narrow width of the positive electrode, the battery may not have sufficient capacity.

[0151] In addition, in a specific embodiment of the present disclosure, the ratio of the distance L1:L2 can be set to 2:1 to 3:1.

[0152] Returning to reference ​ and ​ , a second side SP2 of the separator extends outward from a second side of the second electrode plate E2 and is disposed on an uncoated portion of the first electrode plate E1. Additionally, in a specific embodiment of the present disclosure, the uncoated portion of the first electrode plate can include a plurality of segments, and in this case, the second side of the separator can be arranged to cover the slotted valleys of the cut grooves of the segments of the uncoated portion of the first electrode plate. In an embodiment of the present disclosure, the positions of the slotted valleys between the plurality of segments can be the same.

[0153] In the present disclosure, the electrode assembly can be formed into a wound-core type by winding a first electrode plate, a second electrode plate, and a separator around an axis in one direction, and the wound-core type electrode assembly can have a plurality of winding turns. In the wound-core type electrode assembly, all or at least some of the segments can be radially bent relative to the axis at a bending point, which is any point within the segment. In the present disclosure, the bending point can be any point between the slotted valley and the uppermost end of each segment, and the distance between the uppermost end of the segment and the bending point can be shorter than the distance between the uppermost end of the segment and the slotted valley.

[0154] More specifically, the second side, which is the other end of the separator, can be located between the bending point of the first electrode plate and Bou (the boundary line between the electrode active material portion and the uncoated portion), and further extend beyond the second side of the second electrode plate.

[0155] Subsequently, the uncoated portions of each electrode plate and the size and shape of the segments will be described in more detail.

[0156] In addition, in the present disclosure, the first electrode plate or the second electrode plate or both can have uncoated portions with different heights in the length direction. Additionally, the segments of the uncoated portions can be different in height in the length direction. The shape of each cutting groove can be different, or it can be different in height at the slotted valley. That is, the shape and size of the segments and the shape and size of the cutting grooves can be different.

[0157] In an embodiment of the present disclosure, the uncoated portion includes a core-side uncoated portion adjacent to the core of the electrode assembly, an outer-periphery-side uncoated portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate uncoated portion between the core-side uncoated portion and the outer-periphery-side uncoated portion.

[0158] Preferably, at least one of the core-side uncoated portion or the outer-periphery-side uncoated portion can be smaller in height than the intermediate uncoated portion.

[0159] In the present disclosure, the height of the uncoated portion and the height of the segment refer to the distance from the boundary line Bou between the electrode active material portion and the uncoated portion to the first side. More specifically, in the region where no segments are formed, the height of the uncoated portion refers to the distance from the boundary between the electrode active material portion and the uncoated portion to the first side, and in the region where segments are formed, the first side refers to the position corresponding to the uppermost end of the segment, and the cutting groove portion between the segments is not considered when measuring the height of the uncoated portion in the region where segments are formed.

[0160] In addition, the height of the slotted valley is based on the portion of the cutting groove having the lowest height.

[0161] In the present disclosure, the electrode assembly can be wound into a core type, and in this case, all or at least some of the segments are bent in the radial direction of the electrode assembly (towards the winding center) or in the direction opposite to the radius. The bending of the segments can be performed at a bending point spaced apart from a predetermined height above the slotted valley (the bottom of the cut groove). In the present disclosure, the bending point refers to the point at which the slope of the tangent starts to reach 45° or less when the segment is bent towards the center by an external force. The slope of the tangent refers to the angle between the tangent at the bending point and the plane perpendicular to the winding axis of the electrode assembly.

[0162] In addition, in the present disclosure, the heights corresponding to the slotted valleys of the plurality of cut grooves can be equal or different.

[0163] In addition, in an embodiment of the present disclosure, the bending point can be located at about 2 mm to 3 mm above the slotted valley.

[0164] In the present disclosure, the second side of the separator can be disposed on the uncoated portion of the first electrode plate and at a position lower than the height of the bending point of the segment of the first electrode plate.

[0165] According to an embodiment of the present disclosure, it is possible to control the second side of the separator to be located below the bending point, that is, adjacent to the electrode active material portion, to allow the electrolyte solution to flow into the electrode assembly along the slotted valley (blank space), thereby having a beneficial effect on electrolyte wetting. Specifically, the electrolyte solution is fed into the electrode assembly, and in this case, the electrolyte solution moves into the cut grooves between the segments, and in this case, the electrolyte solution penetrates again into the end portion of the separator near the slotted valley, and finally penetrates into the active material portion of the electrode. As a result, the uniformity of electrolyte wetting within the electrode assembly is increased.

[0166] When the ends of the separator in the width direction are further away in the outward direction of the electrode assembly, the welding characteristics may be adversely affected, and when the ends of the separator in the width direction are closer to the inside of the core, that is, located at an inner position of the electrode assembly, the risk of short - circuit between the positive and negative electrodes is higher.

[0167] Therefore, the present disclosure is characterized in that, as described above, the two ends of the separator in the width direction are controlled to be disposed at specific positions of the first electrode plate and the second electrode plate.

[0168] According to another specific embodiment of the present disclosure, the electrode assembly is wound into a core type, and among the "bent segments" in the uncoated portion of each electrode plate, the "segment having the minimum height" is referred to as the "minimum bent segment".

[0169] In a particular embodiment of the present disclosure, the minimum bent segment in each electrode plate may be 2 mm or greater, and in this case, the height of the minimum bent segment is higher than the height of the bending point. When the height of the segment in the electrode plate is less than 2 mm, there is a possibility that the bending of the segment may not proceed smoothly due to interference between the separator and the segment. In each electrode plate, the minimum bent segment may be determined among segments having a height of 2 mm or greater.

[0170] In addition, in an embodiment of the present disclosure, each electrode plate may further include a segment (segment A) having a height less than the minimum bent segment. In this case, segment A is not bent. In a particular embodiment, segment A may be arranged closer to the core than the other segments among the plurality of segments.

[0171] In an embodiment of the present disclosure, each electrode plate does not include a segment having a height less than the minimum bent segment, and the minimum bent segment may be the minimum segment.

[0172] In an embodiment of the present disclosure, the second side of the separator may be provided at a position less than 50%, 40% or less, 30% or less, 20% or less, or 10% or less of the height Ha of the minimum bent segment of the first electrode plate. Preferably, the second side of the separator may be located on the uncoated portion of the first electrode plate within 30% of the height Ha of the minimum bent segment. In this case, the separator may be arranged such that the grooved valley of the cut groove between the segments of the first electrode plate is covered by the separator to avoid exposure. When the position of the second side of the separator is outside the above range, there is a risk that the separator may be thermally damaged when the segments are welded in a subsequent step.

[0173] According to ​ , the segment 1 of the first electrode plate may be the minimum bent segment, and the second side of the separator may be located at less than 50% or 30% or less of the height Ha of the minimum bent segment. More specifically, the segment 1 may be the minimum bent segment, and the second side of the separator may be located on the uncoated portion of the positive electrode within 30% of the height Ha of the minimum bent segment.

[0174] According to an embodiment of the present disclosure, the second side of the separator may be located within a maximum of 3 mm or a maximum of 1.5 mm from the Bou of the first electrode plate.

[0175] ​ FIG. [FIG. number] is a diagram showing the definition of the width, height, and pitch (i.e., the distance between segments 61) of segment 61 according to an embodiment of the present disclosure.

[0176] Refer to ​, the width C1, height C2, and pitch C3 of the segment 61 are designed to prevent the uncoated portion 43 from tearing when the uncoated portion 43 is bent, sufficiently increasing the number of overlapping layers of the uncoated portion 43 to improve the welding strength and preventing abnormal deformation of the uncoated portion 43. Abnormal deformation refers to irregular deformation caused by the collapse of the C4 portion that fails to maintain a straight state.

[0177] According to an embodiment of the present disclosure, preferably, the width C1 of the segment 61 can be adjusted within a range between 1 mm and 6 mm. When C1 is less than 1 mm, there may be areas or blank spaces (gaps) that do not overlap to an extent that can ensure sufficient welding strength when the segment 61 is bent toward the core. On the contrary, when C1 is greater than 6 mm, due to the curvature of the wound electrode, when the segment 61 is bent, the uncoated portion 43 near the slotted valley may be torn by stress. Additionally, the height C2 of the segment 61 can be adjusted within a range between 2 mm and 10 mm. When the height C2 of the segment 61 is less than 2 mm, the bending of the segment 61 is not completed smoothly, or there are areas or blank spaces (gaps) that do not overlap to an extent that can ensure sufficient welding strength when the segment 61 is bent toward the core. On the contrary, when C2 is greater than 10 mm, it is difficult to manufacture the electrode plate while evenly maintaining the flatness of the uncoated portion in the winding direction X. That is, swelling occurs due to the large height of the uncoated portion.

[0178] In addition, the pitch C3 of the segment 61 can be adjusted within a range between 0.05 mm and 1 mm or between 0.5 mm and 1 mm. When C3 is less than 0.05 mm, when the segment 61 is bent, the uncoated portion 43 near the slotted valley may be torn by stress. On the contrary, when the pitch C3 is greater than 1 mm, there may be areas or blank spaces (gaps) that do not overlap the segment 61 to an extent that can ensure sufficient welding strength when the segment 61 is bent.

[0179] In an embodiment of the present disclosure, the corners of two segments can be connected to each other in a straight line. That is, the bottom of the cutting groove can have a flat straight shape extending along the winding direction X. A circular reinforcement can be added to the corner A.

[0180] The radius r of the circular reinforcement can be 0.02 mm or greater. When the corresponding radius is greater than the above range, the stress dissipation effect will be clearly exerted. The radius of the circular reinforcement can be 0.1 mm or less. When the corresponding radius is greater than 0.1 mm, the stress dissipation effect no longer increases, and the space near the bottom of the cutting groove decreases, resulting in poor electrolyte wetting.

[0181] Return reference ​The width d of the uncoated portion B1 on the core side is designed on the condition that the cavity at the core of the electrode assembly is not blocked when the segment 61 of the uncoated portion B2 in the middle is bent towards the core. B1 .

[0182] In the example, the width d of the uncoated portion B1 on the core side B1 can be increased proportionally to the height C2 of the segment 61 of Group 1.

[0183] In a specific example, when the electrode plate 60 is used to manufacture an electrode assembly for a cylindrical battery cell with a 46800 form factor, depending on the core diameter of the electrode assembly, the width d of the uncoated portion B1 on the core side B1 can be set to 180 mm to 350 mm.

[0184] In an embodiment, the width of each segment group can be designed to form the same winding turn of the electrode assembly.

[0185] In a variant, the width and / or height and / or pitch of the segments 61 in the same segment group can increase or decrease gradually and / or stepwise and / or irregularly within the group.

[0186] Groups 1 to 7 are examples of segment groups. The number of groups and the number of segments 61 in each group can be adjusted so that the segments 61 overlap in multiple layers to maximize stress dissipation during the bending of the uncoated portion 43 and ensure sufficient welding strength.

[0187] In another variant, in the same manner as in the first and second embodiments, the height of the uncoated portion B3 on the outer peripheral side can gradually or stepwise decrease. Additionally, the segment structure of the middle uncoated portion B2 can extend to the uncoated portion B3 on the outer peripheral side (see the dashed line). In this case, in the same manner as the middle uncoated portion B2, the uncoated portion B3 on the outer peripheral side can include multiple segments. In this case, the segments of the uncoated portion B3 on the outer peripheral side can be larger than the middle uncoated portion B2 in terms of width and / or height and / or pitch.

[0188] In a specific example, when the electrode plate 60 is used to manufacture an electrode assembly for a cylindrical battery cell with a 46800 form factor, the segments can be formed into 8 groups. In this case, the segments of Groups 1 to 7 can be formed in the middle uncoated portion B2 in the same manner as in the above variant, and the segments of Group 8 can be formed in the uncoated portion B3 on the outer peripheral side.

[0189] In a specific example, the width d of the uncoated portion B1 on the core side B1It can be from 180 mm to 350 mm. The width of Group 1 can be 35% to 40% of the width of the uncoated portion B1 on the core side. The width of Group 2 can be 130% to 150% of the width of Group 1. The width of Group 3 can be 120% to 135% of the width of Group 2. The width of Group 4 can be 85% to 90% of the width of Group 3. The width of Group 5 can be 120% to 130% of the width of Group 4. The width of Group 6 can be 100% to 120% of the width of Group 5. The width of Group 7 can be 90% to 120% of the width of Group 6. The width of Group 8 can be 115% to 130% of the width of Group 7.

[0190] The widths of Group 1 to Group 8 do not show a pattern of uniform increase or decrease because the width of the segments gradually increases from Group 1 to Group 8, but the number of segments in the group is limited to an integer. Therefore, the number of segments in a specific segment group can be reduced. Thus, the width of the group can have an irregular change from the core to the outer periphery as in the above example.

[0191] That is, when the widths in the winding direction of each of three consecutive adjacent segment groups in the radial direction of the electrode assembly are W1, W2, and W3, the uncoated portion can include a combination of segment groups having a W3 / W2 less than W2 / W1.

[0192] In the above specific example, Group 4 to Group 6 correspond to this. The width ratio of Group 5 to Group 4 is 120% - 130%, and the width ratio of Group 6 to Group 5 is 100% - 120%, that is, a value less than 120% - 130%.

[0193] ​ The definition of the width, height, and pitch of the trapezoidal segment 61' is shown.

[0194] Referring to ​ , the width D1, height D2, and pitch D3 of the segment 61' are designed to prevent the uncoated portion D4 near the slotted valley from tearing during the bending of the uncoated portion 43, sufficiently increasing the number of overlapping layers of the uncoated portion 43 to ensure sufficient welding strength and preventing abnormal deformation of the uncoated portion 43.

[0195] Preferably, the width D1 of the segment 61' can be adjusted within the range between 1 mm and 6 mm. When D1 is less than 1 mm, there may be an area or blank space (gap) where the segment 61' is not overlapped to an extent that can ensure sufficient welding strength when the segment 61' is bent toward the core. On the contrary, when D1 is greater than 6 mm, due to the curvature of the wound electrode, when the segment 61' is bent, the uncoated portion D4 near the slotted valley may be torn by stress. In addition, the height of the segment 61' can be adjusted within the range between 2 mm and 10 mm. When D2 is less than 2 mm, the bending of the segment 61' may not be completed smoothly, or there may be an area or blank space (gap) where the segment 61' is not overlapped to an extent that can ensure sufficient welding strength when the segment 61' is bent toward the core. On the contrary, when D2 is greater than 10 mm, it is difficult to manufacture the electrode plate while uniformly maintaining the flatness of the uncoated portion 43 in the winding direction. In addition, the pitch D3 of the segment 61' can be adjusted within the range between 0.05 mm and 1 mm or between 0.5 mm and 1 mm. When D3 is less than 0.05 mm, the uncoated portion D4 near the slotted valley may be torn by stress when the segment 61' is bent. On the contrary, when D3 is greater than 1 mm, there may be an area or blank space (gap) where the segment 61' is not overlapped to an extent that can ensure sufficient welding strength when the segment 61' is bent.

[0196] When the segment shape is trapezoidal, the pitch D3 can be defined as the distance between the corners of two adjacent segments 61'. The corners of two adjacent segments can be connected to each other in a straight line shape. That is, the bottom of the cut groove can have a flat straight shape extending along the winding direction X.

[0197] A circular reinforcement can be further provided to the corner. Therefore, the stress concentration that may occur at the corner can be reduced.

[0198] The radius r of the circular reinforcement can be 0.02 mm or more. When the corresponding radius is greater than the above range, the stress dissipation effect can be clearly exerted.

[0199] The radius of the circular reinforcement can be 0.1 mm or less. When the corresponding radius is greater than 0.1 mm, the stress dissipation effect no longer increases, and the space near the bottom of the cut groove decreases, resulting in poor electrolyte wetting.

[0200] The pitch C3 and the pitch D3 can be determined relative to the magnitudes C1 and D1 of the widths measured in the winding direction of the adjacent segments 61 and 61' that define the pitch. For example, as the width of the segment in the winding direction increases, the pitch between the segments preferably tends to increase. Therefore, a uniform electrolyte wetting distribution can be achieved along the winding direction of the electrode assembly.

[0201] The width of the segments in the winding direction can be set to gradually increase from the core of the electrode assembly towards the outer periphery. The width of the segments in the winding direction can gradually or stepwise increase from the core of the electrode assembly towards the outer periphery. For example, the widths C1 and D1 of the segments in the winding direction can be in the range between 1 mm and 6 mm, and can decrease towards the core and increase towards the outer periphery.

[0202] Therefore, the pitches C3 and D3 can be in the range between 0.5 mm and 1 mm, and can gradually or stepwise increase from the core of the electrode assembly towards the outer periphery.

[0203] In the fifth embodiment, the plurality of segments 61' can have a lower inner angle θ of a trapezoid that increases from the core to the outer periphery. When the radius of the electrode assembly 70 increases, the curvature increases. When the lower inner angle θ of the segment 61' increases as the radius of the electrode assembly increases, the stress generated in the radial and circumferential directions when bending the segment 61' can be reduced. Additionally, as the lower inner angle θ increases, when the segment 61' is bent, the overlapping area and the number of overlapping layers with the inner segments 61' increase, so that uniform welding strength in the radial and circumferential directions can be ensured and a flat bent surface can be formed.

[0204] In an example, in the case where the electrode plate 70 is used for an electrode assembly of a cylindrical battery cell having a 46800 form factor, when the radius of the electrode assembly 70 increases from 4 mm to 22 mm, the inner angle of the segment 61' can gradually increase in the range between 60° and 85°.

[0205] In a variant, in the same manner as in the first and second embodiments, the height of the uncoated portion B3 on the outer peripheral side can gradually or stepwise decrease. Additionally, the segmented structure of the middle uncoated portion B2 can extend to the uncoated portion B3 on the outer peripheral side (see the dashed line). In this case, in the same manner as the middle uncoated portion B2, the uncoated portion B3 on the outer peripheral side can include a plurality of segments. In this case, the segments of the uncoated portion B3 on the outer peripheral side can be larger than those of the middle uncoated portion B2 in terms of width and / or height and / or pitch.

[0206] As in the fourth and fifth embodiments, when the middle uncoated portion B2 includes a plurality of segments 60, 60', the shape of each segment 60, 60' can be changed to a triangle, a semicircle, a semi-oval or semi-ellipse, a parallelogram, or any other shape.

[0207] In addition, the shapes of the segments 60 and 60' can be changed differently according to the area of the uncoated portion B2 in the middle. In the example, the stress concentration region can have a circular shape (e.g., semi-circular, semi-ovoid, or semi-elliptical) that is conducive to stress dissipation, and the less stressed region can have a polygon (e.g., square, rectangle, trapezoid, parallelogram) that is as wide as possible.

[0208] In the fourth and fifth embodiments, the segmented structure of the uncoated portion B2 in the middle can also be applied to the uncoated portion B1 on the core side. However, when the segmented structure is applied to the uncoated portion B1 on the core side, reverse forming may occur, that is, when bending the segments 60 and 60' of the uncoated portion B2 in the middle according to the curvature of the core, the end of the uncoated portion B1 on the core side bends outward toward the periphery. Therefore, preferably, the uncoated portion B1 on the core side does not have a segmented structure, or even if the uncoated portion B1 on the core side has a segmented structure, it is also preferable to adjust the width and / or height and / or pitch of the segments 60 and 60' in consideration of the curvature of the core to avoid reverse forming.

[0209] When the height of the segment is less than about 3 mm, reverse forming may occur. In addition, when the height of the segment is less than 2 mm, interference between the segment and the diaphragm may occur, which hinders bending. Furthermore, when the height of the segment is less than 4 mm, the process of welding the segments may not be carried out smoothly. Therefore, considering bending, the minimum height H of the segment min can be 2 mm or greater, or 3 mm or greater, or 4 mm or greater, or 5 mm or greater. Therefore, the height of the minimum bending segment can be 2 mm or greater, or 3 mm or greater, or 4 mm or greater, or 5 mm or greater.

[0210] Therefore, when the second side of the diaphragm exists within the range of ±30% of the height of the minimum bending segment Ha among the segments having a height equal to or greater than the minimum bendable height H min (e.g., 2 mm, 3 mm, 4 mm, or 5 mm) in the uncoated portion, wetting can be significantly enhanced. That is, when determining the minimum segment that defines the position of the end SL of the diaphragm in the width direction, segments with a risk of reverse forming or unbent segments can be excluded.

[0211] Described from another perspective, when the second side of the diaphragm exists within the range of ±30% of the greater of the height Ha of the minimum bending segment and the minimum bendable height H min {max(Ha, H min )} existing in the uncoated portion, wetting can be significantly enhanced.

[0212] Described from another perspective, when the second side of the diaphragm is located at the minimum bendable height H minWhen within the range of ±30% thereof, electrolyte wetting can be significantly enhanced. The second side of the separator can be within the range of ±1.5 mm of the boundary (the boundary between the uncoated portion and the electrode active material portion), or within the range of ±1.2 mm of the boundary, or within the range of ±0.9 mm of the boundary, or within the range of ±0.6 mm of the boundary.

[0213] Alternatively, the position of the second side of the separator can be within the range of ±0.3 Ha of the boundary and also within the range of ±1.5 mm of the boundary, or the position of the second side of the separator can be within the range of ±0.3 Ha of the boundary and also within the range of ±1.2 mm of the boundary, or the position of the second side of the separator can be within the range of ±0.3 Ha of the boundary and also within the range of ±0.9 mm of the boundary, or the position of the second side of the separator can be within the range of ±0.3 Ha of the boundary and also within the range of ±0.6 mm of the boundary.

[0214] In the above embodiments (variations), the first electrode plate can be the positive electrode plate, and the second electrode plate can be the negative electrode plate. Alternatively, the first electrode plate can be the negative electrode plate, and the second electrode plate can be the positive electrode plate. In a specific embodiment of the present disclosure, the first electrode plate is the positive electrode plate, and the second electrode plate is the negative electrode plate.

[0215] In the present disclosure, the positive electrode active material coated on the positive electrode plate and the negative electrode active material coated on the negative electrode plate can include any active material known in the art without limitation.

[0216] The positive electrode active material can include a lithium insertion material as the main component, such as layered compounds such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or compounds substituted with one or more transition metals; the chemical formula Li 1+x Mn 2-x O4 (where x is from 0 to 0.33), lithium manganese oxide (LiMnO2) of LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiFe3O4, V2O5, Cu2V2O7; represented by the chemical formula LiNi 1-x M x O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga, x = 0.01 to 0.3) of N-site type lithium nickel oxide; represented by the chemical formula LiMn 2-x M xLithium manganese composite oxides represented by O2 (where M = Co, Ni, Fe, Cr, Zn or Ta, x = 0.01 to 0.1) or Li2Mn3MO8 (where M = Fe, Co, Ni, Cu or Zn); LiMn2O4 in which alkaline earth metal ions partially substitute for lithium; disulfide compounds; Fe2(MoO4)3 or its composite oxides, but not limited thereto.

[0217] The thickness of the positive electrode current collector can be, for example, 3 μm to 500 μm. The positive electrode current collector is not limited to a specific type and can include materials having conductive properties without causing any chemical changes in the battery, such as stainless steel, aluminum, nickel, titanium, sintered carbon, or aluminum or stainless steel treated with carbon, nickel, titanium or silver on the surface. The electrode current collector can have microtextures on the surface to increase the adhesion strength of the positive electrode active material and can be in various forms, such as films, sheets, foils, meshes, porous bodies, foams, non-woven fabrics.

[0218] The positive electrode active material particles can also include a conductive material. Based on the total weight of the mixture containing the positive electrode active material, the conductive material is added in an amount of, for example, 1 wt% to 50 wt%. The conductive material is not limited to a specific type and can include materials having high conductivity without causing any chemical changes in the battery, such as: graphite such as natural graphite and artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black; conductive fibers such as carbon fibers and metal fibers; fluorocarbon; metal powders such as aluminum powder and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive oxides such as titanium oxide; conductive materials such as polyphenylene derivatives.

[0219] In addition, in the present disclosure, the negative electrode plate is made by coating negative electrode active material particles on a negative electrode current collector and drying, and may also include a conductive material, a binder and a solvent as described above when necessary.

[0220] The thickness of the negative electrode current collector can be, for example, 3 μm to 500 μm. The negative electrode current collector is not limited to a specific type and can include materials having conductive properties without causing any chemical changes in the corresponding battery, such as copper, stainless steel, aluminum, nickel, titanium, sintered carbon, or copper or stainless steel and aluminum cadmium alloy treated with carbon, nickel, titanium or silver on the surface. Additionally, in the same manner as the positive electrode current collector, the negative electrode current collector can have microtextures on the surface to increase the adhesion strength of the negative electrode active material and can be in various forms, such as films, sheets, foils, meshes, porous bodies, foams, non-woven fabrics.

[0221] The negative electrode active material can include, for example: carbon such as non-graphitized carbon and graphite-based carbon; such as Li x Fe2O3 (0 ≤ x ≤ 1), Li xWO2 (0 ≤ x ≤ 1), Sn x Me 1-x Me' y O z (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, Group 1, 2, and 3 elements in the periodic table, halogens; 0 < x ≤ 1; 1 ≤ y ≤ 3; 1 ≤ z ≤ 8) such as metal composite oxides; lithium metal; lithium alloys; silicon-based alloys; tin-based alloys; oxides such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, Bi2O5; conductive polymers such as polyacetylene; Li-Co-Ni-based materials.

[0222] The binder polymer that can be used in the electrode is a component that helps to bond the electrode active material particles to the conductive material and to the electrode current collector, and is added, for example, in an amount of 1 wt% to 50 wt% based on the total weight of the mixture including the electrode active material. The binder polymer can include, for example, any one selected from the group consisting of polyvinylidene fluoride-hexafluoropropylene copolymer (PVdF), polyvinylidene fluoride-trichloroethylene copolymer, polymethyl methacrylate, polybutyl acrylate, polyacrylonitrile, polyvinyl pyrrolidone, polyvinyl acetate, polyethylene-vinyl acetate copolymer, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, and carboxymethyl cellulose or a mixture thereof, but is not limited thereto.

[0223] Non-limiting examples of the solvents for manufacturing the electrode can include acetone, tetrahydrofuran, dichloromethane, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane, water, or a mixture thereof. These solvents can provide an appropriate level of viscosity to form a slurry coating on the surface of the electrode current collector at a desired level.

[0224] The negative electrode plate includes a current collector; and a negative electrode active material portion having a predetermined thickness on at least one surface of the current collector and including a negative electrode active material, a binder polymer, and a conductive material, wherein the negative electrode active material portion can include a lower layer region in contact with the current collector and an upper layer region in contact with the lower layer region, and wherein the negative electrode active material portion extends to the surface, and each of the lower region and the upper region can independently include at least one of graphite or a silicon-based compound as the negative electrode active material.

[0225] The lower layer region can include natural graphite as the negative electrode active material, and the upper layer region can include artificial graphite as the negative electrode active material.

[0226] Each of the lower region and the upper region may independently further include a silicon-based compound as the negative electrode active material.

[0227] The silicon-based compound may include at least one of SiOx (0 ≤ x ≤ 2) or SiC.

[0228] According to an embodiment of the present disclosure, the negative electrode may be manufactured by: coating a slurry for the lower layer including the negative electrode active material for the lower layer on a current collector and drying the slurry to form a lower region, and then coating a slurry for the upper layer including the negative electrode active material for the upper layer on the lower region and drying the slurry to form an upper region.

[0229] In addition, according to an embodiment of the present disclosure, the negative electrode may be manufactured by a method including the following steps: preparing a slurry for the lower layer including the negative electrode active material for the lower layer and a slurry for the upper layer including the negative electrode active material for the upper layer;

[0230] coating the slurry for the lower layer on one surface of the negative electrode current collector, and simultaneously or at a predetermined time interval coating the slurry for the upper layer on the slurry for the lower layer; and

[0231] simultaneously drying the coated slurry for the lower layer and the coated slurry for the upper layer to form an active material portion.

[0232] When manufactured using the latter method, a mixed region where different types of active materials are mixed together may exist at the interface between the lower region and the upper region in the negative electrode. When the slurry for the lower layer including the negative electrode active material for the lower layer and the slurry for the upper layer including the negative electrode active material for the upper layer are simultaneously or continuously coated on the current collector at a very short time interval and simultaneously dried to form an active material portion, the slurry for the lower layer and the slurry for the upper layer are mixed together at the interface before and after drying, and a mixed region is formed in a layered form.

[0233] In the active material portion of the negative electrode according to an embodiment of the present disclosure, the weight ratio (or the loading amount ratio per unit area) of the upper region to the lower region may be from 20:80 to 50:50, specifically from 25:75 to 50:50.

[0234] The thicknesses of the lower region and the upper region of the active material portion of the negative electrode of the present disclosure may not exactly match the thicknesses of the coated slurry for the lower layer and the coated slurry for the upper layer. However, after a drying or selective rolling process, the thickness ratio of the lower region and the upper region of the negative electrode active material portion of the present disclosure finally obtained may match the thickness ratio of the coated slurry for the lower layer and the coated slurry for the upper layer.

[0235] Apply the first slurry, and simultaneously or at a predetermined time interval, apply the second slurry on the first slurry. According to an embodiment of the present disclosure, the predetermined time interval may be 0.6 seconds or less, or from 0.02 seconds to 0.6 seconds, or from 0.02 seconds to 0.06 seconds, or from 0.02 seconds to 0.03 seconds. The time interval for applying the first slurry and the second slurry is attributed to the coater, and more preferably, the first slurry and the second slurry may be applied simultaneously. The method of applying the second slurry on the first slurry may use a dual-slot die.

[0236] The step of forming the active material layer may further include a step of rolling the active material portion after the drying step. In this case, the rolling may be performed by a method commonly used in the art such as roll pressing, and for example, may be performed at a pressure from 1 MPa to 20 MPa and a temperature from 15 °C to 30 °C.

[0237] The step of forming the active material portion by simultaneously drying the coating slurry for the lower layer and the coating slurry for the upper layer may be performed by a method commonly used in the art using a combination of a hot air dryer and an infrared dryer.

[0238] The weight percentage of the first binder polymer in the solids of the slurry for the lower layer may be equal to or greater than the weight percentage of the second binder polymer in the solids of the slurry for the upper layer. According to an embodiment of the present disclosure, the weight percentage of the first binder polymer in the solids of the slurry for the lower layer may be 1.0 to 4.2 times, or 1.5 to 3.6 times, or 1.5 to 3 times greater than the weight percentage of the second binder polymer in the solids of the slurry for the upper layer.

[0239] In this case, when the ratio of the weight percentage of the first binder in the coating slurry for the lower layer to the weight percentage of the second binder in the coating slurry for the upper layer satisfies the above range, the amount of the binder in the lower layer region is not too low, so peeling of the electrode layer does not occur, and the amount of the binder in the upper layer region is not too high, so the resistance of the upper part of the electrode is reduced and the fast charging performance can be improved.

[0240] The weight percentage of the first binder polymer in the solids of the slurry for the lower layer may be 2 wt% to 30 wt%, or 5 wt% to 20 wt%, or 5 wt% to 20 wt%, and the percentage (by weight) of the second binder polymer in the solids of the slurry for the upper layer may be 0.5 wt% to 20 wt%, or 1 wt% to 15 wt%, or 1 wt% to 10 wt%, or 2 wt% to 5 wt%.

[0241] The total percentage (by weight) of the first binder polymer and the second binder polymer in the total solids of the slurry for the lower layer and the slurry for the upper layer may be 2 wt% to 20 wt%, or 5 wt% to 15 wt%.

[0242] The separator has a porous polymer substrate; and a porous coating on at least one or both surfaces of the porous polymer substrate, the porous coating comprising inorganic particles and a binder polymer.

[0243] The porous polymer substrate may be a polyolefin-based porous substrate.

[0244] The polyolefin-based porous substrate may be in the form of a film or a nonwoven web. With the porous structure, smooth movement of the electrolyte solution between the positive and negative electrodes can be achieved, increasing the electrolyte wetting of the substrate itself to ensure high ionic conductivity, and preventing an increase in the internal resistance of the electrochemical device to prevent deterioration of the performance of the electrochemical device.

[0245] The polyolefin porous substrate used in the present disclosure may include any planar porous substrate commonly used in electrochemical devices, and its material or shape can be variously selected according to the purpose.

[0246] Non-limiting examples of the polyolefin porous substrate may include films or nonwoven webs of high-density polyethylene, low-density polyethylene, linear low-density polyethylene, ultra-high molecular weight polyethylene, polypropylene, or mixtures thereof, but are not limited thereto.

[0247] The thickness of the polyolefin porous substrate may be 8 μm to 30 μm, but this is provided by way of example, and thicknesses outside the above range may be used in view of the mechanical properties of the battery or the high-rate charge and discharge characteristics.

[0248] The nonwoven sheet according to the present disclosure may be formed of polyethylene (PE), polypropylene (PP), or a mixture thereof. For example, the nonwoven sheet may be made by fiber spinning. For example, the nonwoven sheet may be made by interweaving the melt-spun fibers of the above materials, and the melt-spun fibers of the above materials are produced by melt blowing at the melting point or above the melting point.

[0249] The nonwoven sheet may have an elongation of 200% to 400%, more preferably 300% to 400%. When the elongation is less than 200%, in the case of a nail penetrating the battery, the contact probability between the electrodes increases, and when the elongation is greater than 400%, the area adjacent to the nail penetration area is also stretched, the separator becomes thinner and the barrier decreases.

[0250] The nonwoven sheet has a plurality of pores with an average diameter of 0.1 μm to 10 μm. When the pore diameter is less than 0.1 μm, smooth movement of lithium ions and / or the electrolyte solution cannot be achieved, and when the pore diameter is greater than 10 μm, the effect of preventing contact between the positive and negative electrodes of the present disclosure may not be achieved by stretching the nonwoven sheet in the case of a nail penetrating the battery.

[0251] In addition, the nonwoven sheet may have a porosity of 40% to 70%. When the porosity is less than 40%, smooth movement of lithium ions and / or electrolyte solution may not be achieved, and when the porosity is greater than 70%, the stretching of the nonwoven sheet in the case of a nail penetrating the battery may not achieve the effect of preventing contact between the positive electrode and the negative electrode of the present disclosure. The nonwoven sheet may have an air permeability of 1 to 20 seconds / 100 mL.

[0252] In addition, the thickness of the nonwoven sheet may be 10 μm to 20 μm, but this is provided by way of example, and the thickness is not limited to the above range. Depending on the permeability of the nonwoven sheet, a nonwoven sheet having a thickness other than the above thickness may be used.

[0253] The nonwoven sheet may be laminated to a component of the separator below the nonwoven sheet. Lamination may be performed in a temperature range of 100°C to 150°C, and when lamination is performed below 100°C, no lamination effect occurs, and when lamination is performed above 150°C, part of the nonwoven fabric melts.

[0254] The separator according to an embodiment of the present disclosure laminated and joined under the above conditions has improved nail penetration resistance when compared with a conventional separator of a nonwoven sheet and a separator having a layer including inorganic particles on at least one surface of a film or a nonwoven sheet.

[0255] The inorganic particles packed in contact with each other in the porous coating may be held together by a binder polymer to form an interstitial volume between the inorganic particles, and the interstitial volume between the inorganic particles may become a void space that will form pores.

[0256] The inorganic particles used to form the porous coating may also include inorganic particles, that is, inorganic particles that do not undergo oxidation and / or reduction reactions within the operating voltage range of the electrochemical device (for example, 0 to 5V vs Li / Li+). In particular, using inorganic particles having the ability to transport ions can contribute to increased ionic conductivity and improved performance in the electrochemical device. In addition, using inorganic particles with a high dielectric constant as the inorganic particles helps to increase the degree of dissociation of electrolyte salts (such as lithium salts) in the liquid electrolyte, thereby increasing the ionic conductivity of the electrolyte solution.

[0257] For the above reasons, the inorganic particles may include high dielectric constant inorganic particles having a dielectric constant of 5 or greater, preferably 10 or greater, inorganic particles having the ability to transport lithium ions, and combinations thereof.

[0258] Non-limiting examples of inorganic particles having a dielectric constant of 5 or greater may include BaTiO3, Pb(Zr,Ti)O3 (PZT), Pb 1-x Lax Zr 1-y Ti y O3 (PLZT), PB(Mg 1 / 3 Nb 2 / 3 )O3 - PbTiO3 (PMN - PT), hafnium dioxide (HfO2), SrTiO3, SnO2, CeO2, MgO, NiO, CaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiC, aluminum hydroxides such as boehmite (γ - AlO(OH)), pseudo - boehmite (Al2O3·H2O), diaspore (α - AlO(OH)), bayerite (α - AlO(OH)3), gibbsite (γ - AlO(OH)3), nordstrandite (AlO(OH)3) or mixtures thereof.

[0259] In particular, inorganic particles such as BaTiO3, Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3 (PLZT), PB(Mg 1 / 3 Nb 2 / 3 )O3 - PbTiO3 (PMN - PT) and hafnium oxide (HfO2) can exhibit high dielectric constant characteristics with a dielectric constant of 100 or greater, and have piezoelectricity in which a potential difference occurs between two surfaces due to charges generated when stretched or compressed by applying a predetermined pressure, thereby preventing internal short - circuiting of the two electrodes in the case of an external shock, which helps to improve the safety of the electrochemical device. Additionally, when high - dielectric - constant inorganic particles are used together with inorganic particles having the ability to transport lithium ions as described above, their synergistic effect can be amplified.

[0260] Inorganic particles having the ability to transport lithium ions refer to inorganic particles that contain but do not store lithium and have the function of transporting lithium ions. Since inorganic particles having the ability to transport lithium ions can transport and deliver lithium ions through a type of defect present in the particle structure, the conductivity of lithium ions in the battery can be improved, thereby helping to improve battery performance. Non - limiting examples of inorganic particles having the ability to transport lithium ions can include lithium phosphate (Li3PO4), lithium titanium phosphate (Li x Ti y (PO4)3, 0 < x < 2, 0 < y < 3), lithium aluminum titanium phosphate ((Li x Al y Ti z (PO4)3, 0 < x < 2, 0 < y < 1, 0 < z < 3), (LiAlTiP) such as 14Li2O - 9Al2O3 - 38TiO2 - 39P2O5x O y base glass (0 < x < 4, 0 < y < 13), lanthanum lithium titanate (Li x La y TiO3, 0 < x < 2, 0 < y < 3), such as Li 3.25 Ge 0.25 P 0.75 germanium lithium thiophosphate such as Li x Ge y P z S w , 0 < x < 4, 0 < y < 1, 0 < z < 1, 0 < w < 5), lithium nitride such as Li x N y , 0 < x < 4, 0 < y < 2), SiS2-based glass such as Li3PO4-Li2S-SiS2 (Li x Si y S z , 0 < x < 3, 0 < y < 2, 0 < z < 4), P2S5-based glass such as LiI-Li2S-P2S5 (Li x P y S z , 0 < x < 3, 0 < y < 3, 0 < z < 7) or a mixture thereof.

[0261] In an embodiment of the present disclosure, the inorganic particles may include inorganic particles having hydrophilicity. The inorganic particles having hydrophilicity may include, for example, Al2O3 or aluminum hydroxide-based inorganic particles, and the aluminum hydroxide-based inorganic particles may include, for example, boehmite (γ-AlO(OH)), pseudo-boehmite (Al2O3·H2O), diaspore (α-AlO(OH)), bayerite (α-AlO(OH)3), gibbsite (γ-AlO(OH)3), and nordstrandite (AlO(OH)3). In the present disclosure, the separator may include at least one type of inorganic particles having hydrophilicity. In particular, when a hydrophilic organic solvent such as a carbonate-based organic solvent is used as the organic solvent of the electrolyte solution, using inorganic particles having hydrophilicity in the porous coating of the separator can further improve the electrolyte wetting of the electrode assembly. In an embodiment of the present disclosure, when a polyolefin-based separator substrate is used, since the separator substrate exhibits hydrophobicity, it may be difficult to ensure sufficient electrolyte wetting. In this case, when inorganic particles having hydrophilicity are applied to the porous coating on the surface, the low wetting of the separator caused by the hydrophobicity of the polyolefin-based separator substrate can be prevented. The particle size of the inorganic particles of the porous coating is not limited to a specific range, but may preferably be 0.001 μm - 10 μm to form a coating with a uniform thickness and obtain the best porosity. When the particle size is less than 0.001 μm, it will cause poor dispersion of the inorganic particles, and when the particle size is greater than 10 μm, the thickness of the porous coating increases, and the mechanical properties decrease, and due to the too large pore size, the probability of internal short circuit during battery charge / discharge is high.

[0262] The binder polymer for forming the porous coating may include any one selected from the group consisting of: polyvinylidene fluoride-hexafluoropropylene copolymer (PVdF), polyvinylidene fluoride-trichloroethylene copolymer, polymethyl methacrylate, polybutyl acrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, polyethylene-vinyl acetate copolymer, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, and carboxymethyl cellulose, or a mixture thereof, but is not limited thereto.

[0263] The composition ratio of inorganic particles to binder polymer in the porous coating is preferably in the range of, for example, between 50:50 and 99:1, and more preferably between 70:30 and 95:5. When the ratio of inorganic particles to binder polymer is less than 50:50, the amount of binder polymer increases and the improvement in the thermal safety of the separator may decrease. Additionally, the interstitial volume between the inorganic particles decreases, and the pore size and porosity decrease, and as a result, the battery performance may decrease. When the amount of inorganic particles is greater than 99 parts by weight, the peel resistance of the porous coating may become weak due to the too low amount of binder polymer. The thickness of the porous coating is not limited to a specific range, but is preferably in the range between 0.01 μm and 20 μm. Additionally, the pore size and porosity are not limited to a specific range, but the pore size is preferably in the range between 0.001 μm and 10 μm, and the porosity is preferably in the range between 10% and 90%. The pore size and porosity mainly depend on the size of the inorganic particles, and when inorganic particles having a particle size of, for example, 1 μm or less are used, the size of the formed pores is also about 1 μm or less. The pore structure is filled with an electrolyte solution to be injected later, and the filled electrolyte solution functions in ion transport. When the pore size is less than 0.001 μm and the porosity is less than 10%, the porous coating can act as a resistance layer, and when the pore size is greater than 10 μm and the porosity is greater than 90%, the mechanical properties may decrease.

[0264] The porous coating can be formed by dissolving or dispersing a binder polymer in a dispersion medium, adding inorganic particles to prepare a slurry for forming the porous coating, coating the slurry on at least one surface of a substrate, and drying the slurry. The dispersion medium preferably has a solubility index similar to the binder polymer to be used and a low boiling point. This is to ensure the homogeneity of the mixture and to make it easy to remove the dispersion medium later. Non-limiting examples of available dispersion media can include acetone, tetrahydrofuran, dichloromethane, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane, water, or a mixture thereof.

[0265] It is preferable to grind the inorganic particles after adding them to a dispersion in which the binder polymer is dispersed in a dispersion medium. In this case, as described above, the grinding time is preferably 1 to 20 hours, and the particle size of the ground inorganic particles is preferably 0.001 μm to 10 μm. Commonly used methods can be used for grinding, and in particular, ball milling is preferred.

[0266] Subsequently, a binder polymer dispersion containing dispersed inorganic particles is coated and dried on at least one surface of a porous polymer substrate under humidity conditions of 10% to 80%. The coating method for coating the dispersion on the porous polymer substrate may include known coating methods commonly used in the art, such as dip coating, die coating, roll coating, comma coating, or a combination thereof.

[0267] In addition to inorganic particles and binder polymers, the porous coating may further include additives such as conductive materials.

[0268] The thickness of the separator finally manufactured according to the present disclosure may be 1 μm to 100 μm, or 5 μm to 50 μm. When the thickness is less than 1 μm, the function of the separator cannot be fully exerted, resulting in deterioration of mechanical properties, and when the thickness is greater than 100 μm, the characteristics of the battery may deteriorate during high-rate charging and discharging. In addition, the separator may have a porosity of 40% to 60% and a gas permeability of 150 to 300 seconds / 100 mL.

[0269] According to an embodiment of the present disclosure, the porous polymer substrate may include a polyethylene or polypropylene-based material. In addition, in the porous coating, the inorganic particles may include a coating material based on Al oxide or Si oxide.

[0270] When using the separator according to an embodiment of the present disclosure, since the porous polymer substrate has porous coatings on both sides, a uniform solid electrolyte interface (SEI) layer can be formed through improved electrolyte wetting performance, and a higher gas permeability than that of a conventional separator having an inorganic coating on one surface can be ensured. For example, the gas permeability may be equal to or less than 120 s / 100 cc. In addition, the inorganic porous coatings formed on both surfaces may be at the thickness level of a conventional separator having an inorganic coating on one surface. For example, the thickness may be equal to or less than 15.0 μm.

[0271] In addition, when using the separator according to an embodiment of the present disclosure, the stability of the separator can be improved, thereby ensuring heat resistance and compressive characteristics. Specifically, heat resistance characteristics with a thermal shrinkage characteristic of 5% or less can be ensured based on 180 °C, a puncture strength of 550 gf or more can be ensured, and damage or puncture of the separator at the stepped portion can be prevented when the core is deformed during battery cycling using the separator.

[0272] Hereinafter, the structure of the electrode assembly according to an embodiment of the present disclosure will be described in detail.

[0273] ​It is a cross-sectional view of the core-type electrode assembly 80 taken along the Y-axis direction (winding axis direction) according to an embodiment of the present disclosure.

[0274] The electrode assembly 80 can be fabricated by the winding process described by ​ For ease of description, the protruding structures of the uncoated portions 43a, 43b extending beyond the separator are shown in detail, and the illustration of the winding structure of the first electrode plate, the second electrode plate, and the separator is omitted. In ​ , the upwardly protruding uncoated portion 43a can extend from the first electrode plate, and the downwardly protruding uncoated portion 43b can extend from the second electrode plate.

[0275] ​ The height change pattern of the uncoated portions 43a, 43b is schematically shown. That is, the height of the uncoated portions 43a, 43b can change irregularly according to the position where the cross-section is taken. For example, when the sides of the trapezoidal segments 61, 61' are cut, the height of the uncoated portion in the cross-section is less than the height of the segments 61, 61'. Therefore, the height of the uncoated portions 43a, 43b shown in the drawings depicting the cross-section of the electrode assembly should be understood as corresponding to the average value of the height of the uncoated portions included in each winding turn ( ​ C2 in ​ D2 in ).

[0276] Referring to ​ , the uncoated portion 43a of the first electrode plate includes a core-side uncoated portion B1 adjacent to the core of the electrode assembly 80, an outer-periphery-side uncoated portion B3 adjacent to the outer peripheral surface of the electrode assembly 80, and an intermediate uncoated portion B2 between the core-side uncoated portion B1 and the outer-periphery-side uncoated portion B3.

[0277] Here, the height (length in the Y-axis direction) of the outer-periphery-side uncoated portion B3 is less than the height of the intermediate uncoated portion B2. Therefore, an internal circuit short circuit that occurs when the outer-periphery-side uncoated portion B3 presses against the curled portion of the battery can is prevented.

[0278] Here, the lower uncoated portion 43b has the same structure as the upper uncoated portion 43a. In a variant, the lower uncoated portion 43b can have a conventional electrode plate structure or an electrode plate structure of other embodiments (variants).

[0279] In addition, the ends 81 of the upper uncoated portion 43a and the lower uncoated portion 43b can be bent from the outer periphery of the electrode assembly 80 toward the core. In this case, the outer-periphery-side uncoated portion B3 can be substantially not bent.

[0280] ​FIG. is a cross-sectional view of a wound core type electrode assembly 90 including a first electrode plate and a second electrode plate using the electrode plate 45 of the second embodiment, taken along the Y-axis direction (winding axis direction).

[0281] Referring ​ , the uncoated portion 43a of the first electrode plate includes a core-side uncoated portion B1 adjacent to the core of the electrode assembly 90, an outer-periphery-side uncoated portion B3 adjacent to the outer peripheral surface of the electrode assembly 90, and an intermediate uncoated portion B2 between the core-side uncoated portion B1 and the outer-periphery-side uncoated portion B3.

[0282] Here, the height of the outer-periphery-side uncoated portion B3 is less than the height of the intermediate uncoated portion B2 and gradually or stepwise decreases from the core toward the outer periphery. Therefore, it is possible to prevent an internal circuit short circuit from occurring when the outer-periphery-side uncoated portion B3 presses against the curled portion of the battery can.

[0283] Here, the lower uncoated portion 43b has the same structure as the upper uncoated portion 43a. In a variant, the lower uncoated portion 43b may have a conventional electrode plate structure or an electrode plate structure of other embodiments (variants). Additionally, the ends 91 of the upper uncoated portion 43a and the lower uncoated portion 43b may be bent from the outer periphery of the electrode assembly 90 toward the core. In this case, the outermost side 92 of the outer-periphery-side uncoated portion B3 may be substantially not bent.

[0284] ​ FIG. is a cross-sectional view of a wound core type electrode assembly 100 including a first electrode plate (positive electrode plate) and a second electrode plate (negative electrode plate) using any one of the electrode plates 50, 60, 70 of the third to fifth embodiments (variants), taken along the Y-axis direction (winding axis direction).

[0285] Referring ​ , the uncoated portion 43a of the first electrode plate includes a core-side uncoated portion B1 adjacent to the core of the electrode assembly 100, an outer-periphery-side uncoated portion B3 adjacent to the outer peripheral surface of the electrode assembly 100, and an intermediate uncoated portion B2 between the core-side uncoated portion B1 and the outer-periphery-side uncoated portion B3.

[0286] Here, the height of the core-side uncoated portion B1 is less than the height of the intermediate uncoated portion B2. Additionally, the length of the innermost uncoated portion 43a in the intermediate uncoated portion B2 is equal to or less than the radial length R of the core-side uncoated portion B1. Therefore, when the intermediate uncoated portion B2 is bent, the bent portion does not block the cavity 112 at the core of the electrode assembly 110. When the cavity 112 is not blocked, there is no difficulty in the electrolyte injection process, and the electrolyte solution injection efficiency is improved. Additionally, by inserting a welding jig through the cavity 112, the welding process can be easily performed between the current collector plate of the negative electrode and the battery can.

[0287] In addition, the height of the uncoated portion B3 on the outer peripheral side is smaller than the height of the uncoated portion B2 in the middle. Therefore, it is possible to prevent an internal circuit short circuit from occurring when the uncoated portion B3 on the outer peripheral side presses on the curled portion of the battery can.

[0288] In a variant, different from ​ the height of the uncoated portion B3 on the outer peripheral side can gradually or stepwise decrease. In addition, in ​ the height of the uncoated portion B2 in the middle in a part of the outer periphery is equal, but the height of the uncoated portion B2 in the middle can gradually or stepwise increase from the boundary between the uncoated portion B1 on the core side and the uncoated portion B2 in the middle to the boundary between the uncoated portion B2 in the middle and the uncoated portion B3 on the outer peripheral side.

[0289] Here, the lower uncoated portion 43b has the same structure as the upper uncoated portion 43a. In a variant, the lower uncoated portion 43b can have a conventional electrode plate structure or an electrode plate structure of other embodiments (variants).

[0290] Here, the ends 101 of the upper uncoated portion 43a and the lower uncoated portion 43b can be bent from the outer periphery of the electrode assembly 100 toward the core. In this case, the uncoated portion B1 on the core side and the uncoated portion B3 on the outer peripheral side are substantially not bent.

[0291] Here, when the uncoated portion B2 in the middle includes a plurality of segments, the bending stress can be reduced, thereby preventing tearing or abnormal deformation of the slotted valley portion of the uncoated portion 43. In addition, when adjusting the width and / or height and / or pitch of the segments according to the numerical range of the above-described embodiment, the segment multi-layers sufficiently overlap to ensure the welding strength when the segments are bent toward the core and no empty holes (gaps) are formed on the bending surface (the surface observed from the Y-axis).

[0292] ​ FIG. is a cross-sectional view taken along the Y-axis direction (winding axis direction) of an electrode assembly 110 according to another embodiment of the present disclosure.

[0293] Referring to ​ the electrode assembly 110 is substantially the same as the electrode assembly 100 of ​ except that the height of the uncoated portion B3 on the outer peripheral side is substantially equal to the outermost height of the uncoated portion B2 in the middle.

[0294] The uncoated portion B3 on the outer peripheral side can include a plurality of segments. For details of the plurality of segments, the descriptions of the fourth and fifth embodiments (variants) are substantially equally applicable.

[0295] Here, in the electrode assembly 110, the height of the uncoated portion B1 on the core side is less than the height of the intermediate uncoated portion B2. Additionally, the length H of the innermost uncoated portion in the intermediate uncoated portion B2 is equal to or less than the radial length R of the uncoated portion B1 on the core side.

[0296] Therefore, when the intermediate uncoated portion B2 is bent, the bent portion does not block the cavity 112 at the core of the electrode assembly 110. When the cavity 112 is not blocked, the electrolyte injection process has no difficulty, and the electrolyte solution injection efficiency is improved. Additionally, by inserting the welding jig through the cavity 112, the welding process can be easily performed between the current collector plate of the negative electrode and the battery can.

[0297] In a variant, the structure in which the height of the intermediate uncoated portion B2 gradually or stepwise increases from the core toward the outer periphery can extend to the outer peripheral uncoated portion B3. In this case, the height of the uncoated portion 43a can gradually or stepwise increase from the boundary between the uncoated portion B1 on the core side and the intermediate uncoated portion B2 to the outermost surface of the electrode assembly 110.

[0298] Here, the lower uncoated portion 43b has the same structure as the upper uncoated portion 43a. In a variant, the lower uncoated portion 43b can have a conventional electrode plate structure or the electrode plate structure of other embodiments (variants).

[0299] The ends 111 of the upper uncoated portion 43a and the lower uncoated portion 43b can be bent from the outer periphery of the electrode assembly 110 toward the core. In this case, the uncoated portion B1 on the core side is substantially not bent.

[0300] When the intermediate uncoated portion B2 and the outer peripheral uncoated portion B3 include multiple segments, the bending stress can be reduced, thereby preventing tearing or abnormal deformation in the uncoated portions 43a, 43b near the slotted valley. Additionally, when the width and / or height and / or pitch of the segments are adjusted according to the numerical ranges of the above-described embodiments, the segment layers sufficiently overlap to ensure the welding strength when the segments are bent toward the core and no empty holes (gaps) are formed on the bending surface (the surface observed from the Y-axis).

[0301] ​ is a cross-sectional view taken along the Y-axis direction (the winding axis direction) of an electrode assembly 120 according to another embodiment of the present disclosure.

[0302] Refer to ​ and the electrode assembly 120 has substantially the same configuration as the ​ electrode assembly 100, except for the pattern of the height of the intermediate uncoated portion B2 that gradually or stepwise increases and then decreases.

[0303] The height change of the middle uncoated portion B2 can be adjusted by adjusting the stepped pattern included in the middle uncoated portion B2 (see ​ ), or the height of the segmented portions (see ​ or ​ ).

[0304] In the electrode assembly 120, the height of the core-side uncoated portion B1 is less than the height of the middle uncoated portion B2. Additionally, the height H of the innermost uncoated portion in the middle uncoated portion B2 is equal to or less than the radial length R of the core-side uncoated portion B1.

[0305] Therefore, when the middle uncoated portion B2 is bent towards the core, the bent portion does not block the cavity 122 at the core of the electrode assembly 120. When the cavity 122 is not blocked, the electrolyte injection process has no difficulty, and the electrolyte solution injection efficiency is improved. Additionally, by inserting a welding jig through the cavity 122, the welding process can be easily performed between the current collector plate of the negative electrode and the battery can.

[0306] Furthermore, the height of the outer peripheral-side uncoated portion B3 is less than the height of the middle uncoated portion B2. Therefore, it is possible to prevent an internal circuit short circuit from occurring when the outer peripheral-side uncoated portion B3 presses on the curled portion of the battery can. In a variant, the height of the outer peripheral-side uncoated portion B3 can gradually or stepwise decrease towards the outer periphery.

[0307] Here, the lower uncoated portion 43b has the same structure as the upper uncoated portion 43a. In a variant, the lower uncoated portion 43b can have a conventional electrode plate structure or the electrode plate structure of other embodiments (variants).

[0308] Here, the ends 121 of the upper uncoated portion 43a and the lower uncoated portion 43b can be bent from the outer periphery of the electrode assembly 120 towards the core. In this case, the core-side uncoated portion B1 and the outer peripheral-side uncoated portion B3 are substantially not bent.

[0309] Here, when the middle uncoated portion B2 includes a plurality of segments, the bending stress can be reduced, thereby preventing tearing or abnormal deformation of the uncoated portions 43a, 43b. Additionally, when adjusting the width and / or height and / or pitch of the segments according to the numerical ranges of the above-described embodiments, the segmented layers sufficiently overlap to ensure the welding strength when the segments are bent towards the core and no empty holes (gaps) are formed on the bent surface (the surface observed from the Y-axis).

[0310] ​ is a cross-sectional view taken along the Y-axis direction (the winding axis direction) of an electrode assembly 130 according to another embodiment of the present disclosure.

[0311] Referring to ​ , the electrode assembly 130 has the same as​ has a configuration substantially the same as that of the electrode assembly 120, except that the height of the uncoated portion B3 on the outer peripheral side gradually or stepwise decreases from the boundary between the uncoated portion B3 on the outer peripheral side and the uncoated portion B2 in the middle toward the outermost surface of the electrode assembly 130.

[0312] The change in the height of the uncoated portion B3 on the outer peripheral side can be achieved by extending the stepped pattern (see ​ ) included in the uncoated portion B2 in the middle to the uncoated portion B3 on the outer peripheral side and gradually or stepwise decreasing the height of the pattern toward the outer periphery. Additionally, in another variant, the change in the height of the uncoated portion B3 on the outer peripheral side can be achieved by extending the segmented structure of the uncoated portion B2 in the middle to the uncoated portion B3 on the outer peripheral side and gradually or stepwise decreasing the height of the segments toward the outer periphery.

[0313] In the electrode assembly 130, the height of the uncoated portion B1 on the core side is less than the height of the uncoated portion B2 in the middle. Additionally, the height H of the innermost uncoated portion in the uncoated portion B2 is equal to or less than the radial length R of the uncoated portion B1 on the core side.

[0314] Therefore, when the uncoated portion B2 in the middle is bent toward the core, the bent portion does not block the cavity 132 at the core of the electrode assembly 120. When the cavity is not blocked, there is no difficulty in the electrolyte injection process, and the electrolyte solution injection efficiency is improved. Additionally, by inserting the welding jig through the cavity 132, the welding process can be easily performed between the current collector plate of the negative electrode and the battery can.

[0315] Here, the lower uncoated portion 43b has the same structure as the upper uncoated portion 43a. In a variant, the lower uncoated portion 43b can have a conventional electrode plate structure or an electrode plate structure of other embodiments (variants).

[0316] Here, the ends 131 of the upper uncoated portion 43a and the lower uncoated portion 43b can be bent from the outer periphery of the electrode assembly 130 toward the core. In this case, the uncoated portion B1 on the core side is substantially not bent.

[0317] When the uncoated portion B2 in the middle and the uncoated portion B3 on the outer peripheral side include multiple segments, the bending stress can be reduced, thereby preventing tearing or abnormal deformation of the grooved valley portions of the uncoated portions 43a, 43b. Additionally, when adjusting the width and / or height and / or pitch of the segments according to the numerical ranges of the above - described embodiments, the segmented layers fully overlap to ensure the welding strength when the segments are bent toward the core and no empty holes (gaps) are formed on the bending surface (the surface observed from the Y - axis).

[0318] Various electrode assembly structures according to the embodiments of the present disclosure can be applied to wound - core type cylindrical battery cells.

[0319] Preferably, the cylindrical battery cell can be, for example, a cylindrical battery cell 10 having a form factor ratio greater than about 0.4 (defined as the value obtained by dividing the diameter of the cylindrical battery cell by its height, i.e., the ratio of the diameter Φ to the height H).

[0320] Here, the form factor refers to the value indicating the diameter and height of the cylindrical battery cell. The cylindrical battery cell according to an embodiment of the present disclosure can be, for example, a 46110 cell, a 48750 cell, a 48110 cell, a 48800 cell, or a 46800 cell. In the numbers representing the form factor, the first two numbers indicate the diameter of the cell, the next two numbers indicate the height of the cell, and the last number 0 indicates that the cross-section of the cell is circular.

[0321] When an electrode assembly with a jointless structure is applied to a cylindrical battery cell having a form factor ratio greater than 0.4, the uncoated portion is prone to being torn due to the high stress applied in the radial direction when bending the uncoated portion. In addition, it is necessary to increase the number of overlapping layers of the uncoated portion to an amount sufficient to ensure sufficient welding strength and reduce resistance when welding the current collector plate to the bent surface of the uncoated portion. These requirements can be met by the electrode plate and the electrode assembly according to an embodiment (variant) of the present disclosure.

[0322] The battery cell according to an embodiment of the present disclosure can be a cylindrical battery cell having an approximately cylindrical shape, having a diameter of about 46 mm, a height of about 110 mm, and a form factor ratio of 0.418.

[0323] The battery cell according to another embodiment can be a cylindrical battery cell having an approximately cylindrical shape, having a diameter of about 48 mm, a height of about 75 mm, and a form factor ratio of 0.640.

[0324] The battery cell according to another embodiment can be a cylindrical battery cell having an approximately cylindrical shape, having a diameter of about 48 mm, a height of about 110 mm, and a form factor ratio of 0.418.

[0325] The battery cell according to another embodiment can be a cylindrical battery cell having an approximately cylindrical shape, having a diameter of about 48 mm, a height of about 80 mm, and a form factor ratio of 0.600.

[0326] The battery cell according to another embodiment can be a cylindrical battery cell having an approximately cylindrical shape, having a diameter of about 46 mm, a height of about 80 mm, and a form factor ratio of 0.575.

[0327] Conventionally, battery cells having a ratio of form factor of about 0.4 or less have been used. That is, for example, 18650 cells and 21700 cells have been used. The 18650 cell has a diameter of about 18 mm, a height of about 65 mm, and a ratio of form factor of 0.277. The 21700 cell has a diameter of about 21 mm, a height of about 70 mm, and a ratio of form factor of 0.300.

[0328] Hereinafter, a cylindrical battery cell according to an embodiment of the present disclosure will be described in detail.

[0329] ​ is a cross-sectional view taken along the Y-axis direction of a cylindrical battery cell 140 according to an embodiment of the present disclosure.

[0330] Referring to ​ , a cylindrical battery cell 140 according to an embodiment of the present disclosure includes: an electrode assembly 141 including a first electrode plate, a separator, and a second electrode plate; a battery can 142 that houses the electrode assembly 141; and a seal 143 that seals an open end of the battery can 142.

[0331] The battery can 142 is a cylindrical container having an opening at the top. The battery can 142 is made of a metal having conductive properties, such as aluminum or steel. The battery can 142 houses the electrode assembly 141 together with an electrolyte in an internal space through the top opening.

[0332] The electrolyte may be a salt having a structure such as A + B - . Here, A + includes an alkali metal cation, such as Li + , Na + , K + , or a combination thereof, and B - includes at least one anion selected from the group consisting of: F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , AlO4 - , AlCl4 - , PF6 - , SbF6 - , AsF6 - , BF2C2O4 - , BC4O8 - , (CF3)2PF4 - , (CF3)3PF3- ,(CF3)4PF2 - ,(CF3)5PF - ,(CF3)6P - ,CF3SO3 - ,C4F9SO3 - ,CF3CF2SO3 - ,(CF3SO2)2N - ,(FSO2)2N - ,CF3CF2(CF3)2CO - ,(CF3SO2)2CH - ,(SF5)3C - ,(CF3SO2)3C - ,CF3(CF2)7SO3 - ,CF3CO2 - ,CH3CO2 - ,SCN - and (CF3CF2SO2)2N - 。

[0333] The electrolyte can be dissolved in an organic solvent. The organic solvent is not limited to a specific type and can include solvents for electrolyte solutions of electrochemical devices. For example, the organic solvent can include carbonate-based solvents, including propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), and dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), γ-butyrolactone, or a mixture thereof.

[0334] The electrode assembly 141 can have a wound core shape. As ​ shown, the electrode assembly 141 can be manufactured by stacking a lower separator, a first electrode plate, an upper separator, and a second electrode plate in sequence at least once to form a stacked body and winding the stacked body around a winding center C.

[0335] The first electrode plate and the second electrode plate have different polarities. That is, one is of positive polarity and the other is of negative polarity. At least one of the first electrode plate and the second electrode plate can have the electrode plate structure according to the above embodiments (variations). In addition, the other of the first electrode plate and the second electrode plate can have a conventional electrode plate structure or an electrode plate structure according to the embodiments (variations).

[0336] The uncoated portion 146a of the first electrode plate and the uncoated portion 146b of the second electrode plate protrude from the upper and lower portions of the electrode assembly 141, respectively. The first electrode plate has the electrode plate structure of the first embodiment (variant). Therefore, the uncoated portion 146a of the first electrode plate has a height of the outer peripheral side uncoated portion B3 that is smaller than the height of the other uncoated portion. The outer peripheral side uncoated portion B3 is spaced apart from the inner peripheral surface (especially the crimped portion 147) of the battery can 142 by a predetermined distance. Therefore, contact between the outer peripheral side uncoated portion B3 of the first electrode plate and the battery can 142 electrically connected to the second electrode plate can be avoided, thereby preventing an internal short circuit of the battery cell 140.

[0337] The uncoated portion 146b of the second electrode plate has an equal height. In a variant, the uncoated portion 146b of the second electrode plate may have the same structure as the uncoated portion 146a of the first electrode plate. In another variant, the uncoated portion 146b of the second electrode plate may selectively have the uncoated portion structure of the electrode plate according to the embodiment (variant).

[0338] The sealing body 143 may include a cover plate 143a, a first gasket 143b that provides sealing between the top plate 143a and the battery can 142 and has insulating properties, and a connection plate 143c that is electrically and mechanically coupled to the top plate 143a.

[0339] The cover plate 143a is a component made of a metal having conductive properties and covers the top opening portion of the battery can 142. The cover plate 143a is electrically connected to the uncoated portion 146a of the first electrode plate and is electrically isolated from the battery can 142 by the first gasket 143b. Therefore, the cover plate 143a can be used as the first electrode terminal of the cylindrical battery cell 140.

[0340] The cover plate 143a is mounted on the crimped portion 147 of the battery can 142 and is fixed by a crimped portion 148. The first gasket 143b may be provided between the cover plate 143a and the crimped portion 148 to ensure the sealing of the battery can 142 and the electrical insulation between the battery can 142 and the cover plate 143a. The cover plate 143a may have a protruding portion 143d that protrudes upward from the central portion.

[0341] The battery can 142 is electrically connected to the uncoated portion 146b of the second electrode plate. Therefore, the battery can 142 has the same polarity as the second electrode plate. When the second electrode plate has a negative polarity, the battery can 142 also has a negative polarity.

[0342] The battery can 142 has a curled edge portion 147 and a crimped portion 148 at the upper end. The curled edge portion 147 is formed by curling around the outer peripheral surface of the battery can 142. The curled edge portion 147 can prevent the electrode assembly 141 housed in the battery can 142 from slipping out through the top opening portion of the battery can 142, and can be used as a support on which the sealing body 143 is mounted.

[0343] The inner peripheral surface of the curled edge portion 147 is spaced apart from the uncoated portion B3 on the outer peripheral side of the first electrode plate by a predetermined distance. More specifically, the lower end of the inner peripheral surface of the curled edge portion 147 is spaced apart from the uncoated portion B3 on the outer peripheral side of the first electrode plate by a predetermined distance. In addition, since the uncoated portion B3 on the outer peripheral side has a small height, when the battery can 12 is curled inward to form the curled edge portion 147, the uncoated portion B3 on the outer peripheral side is substantially not affected. Therefore, the uncoated portion B3 on the outer peripheral side is not squeezed by other components such as the curled edge portion 147, thereby preventing partial deformation of the electrode assembly 141 and preventing internal short circuit of the cylindrical battery cell 140.

[0344] Preferably, when the curling depth of the curled edge portion 147 is defined as D1 and the radial length from the inner peripheral surface of the battery can 142 to the boundary between the uncoated portion B3 on the outer peripheral side and the uncoated portion B2 in the middle is defined as D2, the relational expression D1 ≤ D2 can be satisfied. In this case, when the battery can 142 is curled to form the curled edge portion 147, the uncoated portion B3 on the outer peripheral side can be substantially prevented from being damaged.

[0345] The crimped portion 148 is formed on the curled edge portion 147. The crimped portion 148 extends and bends to cover the outer peripheral surface of the cover plate 143a on the curled edge portion 147 and a part of the upper surface of the cover plate 143a.

[0346] The cylindrical battery cell 140 may further include a first current collector plate 144 and / or a second current collector plate 145 and / or an insulator 146.

[0347] The first current collector plate 144 is connected to the upper part of the electrode assembly 141. The first current collector plate 144 is made of a metal having conductive properties such as aluminum, copper, nickel, etc., and is electrically connected to the uncoated portion 146a of the first electrode plate. The lead wire 149 may be connected to the first current collector plate 144. The lead wire 149 may extend upward from the electrode assembly 141 and be connected to the connection plate 143c or directly to the lower surface of the cover plate 143a. The connection between the lead wire 149 and other components can be achieved by welding.

[0348] Preferably, the first current collector plate 144 may be integrally formed with the lead wire 149. In this case, the lead wire 149 may have a long plate shape extending outward from the center of the first current collector plate 144.

[0349] The first current collector plate 144 may have a plurality of uneven portions (not shown) formed radially on its lower surface. When there are radial uneven portions, the uneven portions can be imprinted on the uncoated portion 146a of the first electrode plate by pressing the first current collector plate 144.

[0350] The first current collector plate 144 is connected to the end of the uncoated portion 146a of the first electrode plate. The connection between the uncoated portion 146a and the first current collector plate 144 can be achieved, for example, by laser welding. Laser welding can be completed by melting a part of the current collector plate substrate. In a variant, the welding between the first current collector plate 144 and the uncoated portion 146a can be completed with solder interposed therebetween. In this case, the solder may have a lower melting point than the first current collector plate 144 and the uncoated portion 146a. Laser welding can be replaced by resistance welding, ultrasonic welding, etc.

[0351] The second current collector plate 145 may be connected to the lower surface of the electrode assembly 141. The surface of the second current collector plate 145 can be connected to the uncoated portion 146b of the second electrode plate by welding, and the opposite surface can be connected to the inner bottom surface of the battery can 142 by welding. The connection structure between the second current collector plate 145 and the uncoated portion 146b of the second electrode plate can be substantially the same as the connection structure between the first current collector plate 144 and the uncoated portion 146a of the first electrode plate.

[0352] The uncoated portions 146a, 146b are not limited to the shown structure. Therefore, the uncoated portions 146a, 146b can selectively have not only the conventional uncoated portion structure but also the uncoated portion structure of the electrode plate according to the embodiment (variant).

[0353] The insulator 146 can cover the first current collector plate 144. Since the insulator 146 covers the first current collector plate 144 on the upper surface of the first current collector plate 144, direct contact between the first current collector plate 14 and the inner peripheral surface of the battery can 142 can be prevented.

[0354] The insulator 146 has a lead hole 151, and the lead 149 extending upward from the first current collector plate 144 is pulled outwards through the lead hole 151. The lead 149 extends upward through the lead hole 151 and is connected to the lower surface of the connection plate 143c or the lower surface of the cover plate 143a.

[0355] The edge region of the insulator 146 can be disposed between the first current collector plate 144 and the crimped portion 147 to fix the combination of the electrode assembly 141 and the first current collector plate 144. Therefore, the assembly stability of the battery cell 140 can be improved by the limited movement of the combination of the electrode assembly 141 and the first current collector plate 144 in the height direction of the battery cell 140.

[0356] The insulator 146 can be made of a polymer resin having insulating properties. In an example, the insulator 146 can include polyethylene, polypropylene, polyimide, or polybutylene terephthalate.

[0357] The battery can 142 can further include an exhaust portion 152 in the lower surface. The exhaust portion 152 corresponds to a region having a thickness smaller than that of the surrounding region on the lower surface of the battery can 142. The exhaust portion 152 is structurally fragile compared to the surrounding region. Therefore, when the internal pressure rises above a predetermined level due to a failure or mistake in the cylindrical battery cell 140, the exhaust portion 152 may rupture to discharge the gas generated in the battery can 142.

[0358] The exhaust portion 152 can be formed continuously or discontinuously in a circular pattern on the lower surface of the battery can 142. In a variant, the exhaust portion 152 can be formed in a straight line pattern or any other pattern.

[0359] ​ is a cross-sectional view taken along the Y-axis direction of a cylindrical battery cell 150 according to another embodiment of the present disclosure.

[0360] Referring to ​ [[ID=!6]]In addition to using the electrode plate structure of the second embodiment (variant) in the uncoated portion 146a of the first electrode plate, the cylindrical battery cell 150 has the same configuration as the ​ cylindrical battery cell 140.

[0361] Referring to ​ the uncoated portion 146a of the first electrode plate can have an outer peripheral side uncoated portion B3 whose height gradually or stepwise decreases toward the inner peripheral surface of the battery can 142. Preferably, the imaginary line connecting the uppermost ends of the outer peripheral side uncoated portion B3 can have the same or similar shape as the inner peripheral surface of the crimped portion 147.

[0362] The outer peripheral side uncoated portion B3 forms an inclined surface. Therefore, when the battery can 142 is crimped to form the crimped portion 147, damage to the outer peripheral side uncoated portion B3 due to the extrusion of the crimped portion 147 can be prevented. In addition, an internal short circuit caused by contact between the outer peripheral side uncoated portion B3 and the battery can 142 having a different polarity can be suppressed.

[0363] The remaining configuration of the cylindrical battery cell 150 is substantially the same as the previous description (variant).

[0364] The uncoated portions 146a, 146b are not limited to the structures shown. Therefore, the uncoated portions 146a, 146b can selectively have not only the conventional uncoated portion structure but also the uncoated portion structure of the electrode plate according to the embodiment (variant).

[0365] ​ FIG. 3 is a cross-sectional view taken along the Y-axis direction of a cylindrical battery cell 160 according to another embodiment of the present disclosure.

[0366] Referring to ​ FIG. 3, when the cylindrical battery cell 160 is compared with the above-described cylindrical battery cells 140 and 150, the configurations are substantially the same except that the lead wire 149 connected to the first current collector plate 144 is directly connected to the cover plate 143a of the sealing body 143 through the lead wire hole 151 of the insulator 146, and the insulator 146 and the first current collector plate 144 are in close contact with the lower surface of the cover plate 143a.

[0367] In the cylindrical battery cell 160, the diameter of the first current collector plate 144 and the outermost diameter of the middle non-coated portion B2 are smaller than the minimum inner diameter of the battery can 142. Additionally, the diameter of the first current collector plate 144 may be equal to or greater than the outermost diameter of the middle non-coated portion B2.

[0368] Specifically, the minimum inner diameter of the battery can 142 may correspond to the inner diameter of the battery can 142 at the position where the crimped portion 147 is formed. In this case, the diameter of the first current collector plate 144 and the outermost diameter of the middle non-coated portion B2 are smaller than the inner diameter of the battery can 142 at the position where the crimped portion 147 is formed. Additionally, the diameter of the first current collector plate 144 may be equal to or greater than the outermost diameter of the middle non-coated portion B2. The edge region of the insulator 146 may be bent downward and disposed between the outer peripheral non-coated portion B3 and the crimped portion 147 to fix the combination of the electrode assembly 141 and the first current collector plate 144.

[0369] Preferably, the insulator 146 may include a portion covering the outer peripheral non-coated portion B3 and a portion covering the first current collector plate 144, and the portion connecting the two portions may have a bent shape to conform to the curved shape of the crimped portion 147. The insulator 146 may insulate the outer peripheral non-coated portion B3 from the inner peripheral surface of the crimped portion 147, and may also insulate the first current collector plate 144 from the inner peripheral surface of the crimped portion 147.

[0370] The first current collector plate 144 may be located at a position higher than the lower end of the crimped portion 147 and is connected to the core-side uncoated portion B1 and the intermediate uncoated portion B2. In this case, the crimping depth D1 of the crimped portion 147 is equal to or less than the distance D2 from the inner peripheral surface of the battery can 142 to the boundary between the outer peripheral side uncoated portion B3 and the intermediate uncoated portion B2. Therefore, the core-side uncoated portion B1, the intermediate uncoated portion B2, and the first current collector plate 144 connected thereto may be located at a position higher than the lower end of the crimped portion 147. The lower end of the crimped portion 147 refers to the grooved valley portion between the portion of the battery can 142 that houses the electrode assembly 141 and the crimped portion 147.

[0371] Since the core-side uncoated portion B1 and the intermediate uncoated portion B2 occupy the internal space of the crimped portion 147 in the radial direction, the blank space between the electrode assembly 141 and the cover plate 143a can be minimized. Additionally, the connection plate 143c located in the blank space between the electrode assembly 141 and the cover plate 143a is omitted. Therefore, the lead 149 of the first electrode plate 144 can be directly connected to the lower surface of the cover plate 143a. With the above structure, the blank space inside the battery cell can be reduced, and the energy density can be maximized as much as the reduced blank space.

[0372] In the cylindrical battery cell 160, the first current collector plate 144 and the second current collector plate 145 can be welded to the ends of the uncoated portions 146a, 146b in the same manner as in the above-described embodiment.

[0373] The uncoated portions 146a, 146b are not limited to the shown structure. Therefore, the uncoated portions 146a, 146b can selectively have not only the conventional uncoated portion structure but also the uncoated portion structure of the electrode plate according to the embodiment (variant).

[0374] <UNK> ​ is a cross-sectional view taken along the Y-axis of a cylindrical battery cell 170 according to another embodiment of the present disclosure.

[0375] Referring to ​ when comparing the cylindrical battery cell 170 with the ​ shown cylindrical battery cell 140, the structure of the electrode assembly is basically the same, and the difference between them is that the remaining structure except the electrode assembly is changed.

[0376] Specifically, the cylindrical battery cell 170 includes a battery can 171 with a riveted terminal 172 installed therethrough. The riveted terminal 172 is installed on the closed surface (the upper surface in the figure) of the battery can 171. The riveted terminal 172 is riveted into a through-hole of the battery can 171, and a second washer 173 with insulating properties is inserted between the riveted terminal 172 and the battery can 171. The riveted terminal 172 is exposed to the outside in a direction opposite to the direction of gravity.

[0377] The riveted terminal 172 includes a terminal exposed portion 172a and a terminal inserted portion 172b. The terminal exposed portion 172a is exposed to the outside of the closed surface of the battery can 171. The terminal exposed portion 172a may be located at a substantially central portion of the closed surface of the battery can 171. The maximum diameter of the terminal exposed portion 172a may be greater than the maximum diameter of the through-hole of the battery can 171. The terminal inserted portion 172b may pass substantially through the central portion of the closed surface of the battery can 171 and be electrically connected to the uncoated portion 146a of the first electrode plate. The terminal inserted portion 172b may be riveted to the inner surface of the battery can 171. That is, the end of the terminal inserted portion 172b may have a bent shape toward the inner surface of the battery can 171. The maximum diameter of the end of the terminal inserted portion 172b may be greater than the maximum diameter of the through-hole of the battery can 171.

[0378] The bottom surface of the terminal inserted portion 172b may be welded to the first current collector plate 144, and the first current collector plate 144 is connected to the uncoated portion 146a of the first electrode plate. An insulating cover 174 made of an insulating material may be provided between the first current collector plate 144 and the inner surface of the battery can 171. The insulating cover 174 covers the top of the first current collector plate 144 and the upper edge of the electrode assembly 141. Therefore, a short circuit caused by contact between the uncoated portion B3 on the outer peripheral side of the electrode assembly 141 and the inner surface of the battery can 171 with a different polarity can be prevented. The terminal inserted portion 172b of the riveted terminal 172 may be welded to the first current collector plate 144 through the insulating cover 174.

[0379] The second washer 173 is provided between the battery can 171 and the riveted terminal 172 to prevent electrical contact between the battery can 171 and the riveted terminal 172 with opposite polarities. Therefore, the upper surface of the battery can 171 having an approximately flat shape can be used as the second electrode terminal of the cylindrical battery cell 170.

[0380] The second washer 173 includes a washer exposed portion 173a and a washer insertion portion 173b. The washer exposed portion 173a is disposed between the terminal exposed portion 172a of the riveted terminal 172 and the battery can 171. The washer insertion portion 173b is disposed between the terminal insertion portion 172b of the riveted terminal 172 and the battery can 171. When the riveted terminal insertion portion 172b is inserted, the washer insertion portion 173b can be deformed together and be in close contact with the inner surface of the battery can 171. The second washer 173 may include, for example, a polymer resin having insulating properties.

[0381] The washer exposed portion 173a of the second washer 173 may extend to cover the outer peripheral surface of the terminal exposed portion 172a of the riveted terminal 172. When the second washer 173 covers the outer peripheral surface of the riveted terminal 172, a short circuit can be prevented during the process of connecting an electrical connection component such as a bus bar to the upper surface of the riveted terminal 172 and / or the battery can 171. Although not shown, the washer exposed portion 173a may extend to cover the outer peripheral surface and a part of the upper surface of the terminal exposed portion 172a.

[0382] When the second washer 173 includes a polymer resin, the second washer 173 can be joined to the battery can 171 and the riveted terminal 172 by heat fusion. In this case, the sealing performance at the joining interface between the second washer 173 and the riveted terminal 172 and at the joining interface between the second washer 173 and the battery can 171 can be enhanced. In addition, when the washer exposed portion 173a of the second washer 173 extends to the upper surface of the terminal exposed portion 172a, the riveted terminal 172 and the second washer 173 can be joined together integrally by insert molding.

[0383] The remaining area 175 except for the area occupied by the riveted terminal 172 and the second washer 173 on the upper surface of the battery can 171 corresponds to a second electrode terminal having a polarity opposite to that of the riveted terminal 172.

[0384] The second current collector plate 176 is joined to the lower portion of the electrode assembly 141. The second current collector plate 176 is made of a conductive metal such as aluminum, steel, copper, nickel, etc., and is electrically connected to the uncoated portion 146b of the second electrode plate.

[0385] Preferably, the second current collector plate 176 is electrically connected to the battery can 171. To this end, at least a part of the edge region of the second current collector plate 176 may be fixed between the inner surface of the battery can 171 and the first gasket 178b. In an example, at least a part of the edge region of the second current collector plate 176 may be fixed to the curled portion 180 by welding while being supported on the bottom surface of the curled portion 180 at the lower end of the battery can 171. In a variant, at least a part of the edge region of the second current collector plate 176 may be directly welded to the inner wall surface of the battery can 171.

[0386] The second current collector plate 176 may have a plurality of uneven portions (not shown) radially formed on the surface opposite to the uncoated portion 146b. When forming the uneven portions, the uneven portions may be imprinted on the uncoated portion 146b by pressing the second current collector plate 176.

[0387] Preferably, the ends of the second current collector plate 176 and the uncoated portion 146b may be joined by welding (e.g., laser welding).

[0388] The seal 178 that seals the bottom open end of the battery can 171 includes a cover plate 178a and a first gasket 178b. The first gasket 178b electrically isolates the cover plate 178a from the battery can 171. The crimping portion 181 fixes the edge of the cover plate 178a and the first gasket 178b together. The cover plate 178a has an exhaust portion 179. The configuration of the exhaust portion 179 is substantially the same as that of the above-described embodiment (variant).

[0389] Preferably, the cover plate 178a is made of a conductive metal. However, since the first gasket 178b is provided between the cover plate 178a and the battery can 171, the cover plate 178a does not have an electrode property. The seal 178 seals the open end on the bottom of the battery can 171 and performs an exhaust function when the internal pressure of the battery cell 170 rises above a threshold value.

[0390] Preferably, the riveting terminal 172 electrically connected to the uncoated portion 146a of the first electrode plate serves as the first electrode terminal. Additionally, in the battery can 171 electrically connected to the uncoated portion 146b of the second electrode plate through the second current collector plate 176, the portion 175 of the upper surface of the battery can 171 excluding the riveting terminal 172 serves as the second electrode terminal having a polarity different from that of the first electrode terminal. When the two electrode terminals are located at the upper part of the cylindrical battery cell 170, electrical connection components such as busbars can be placed only on one side of the cylindrical battery cell 170. This can simplify the battery pack structure and improve the energy density. Additionally, since the portion 175 serving as the second electrode terminal is approximately flat in shape, sufficient welding area can be ensured when welding electrical connection components such as busbars. Therefore, the cylindrical battery cell 170 can reduce the resistance at the welding portion of the electrical connection component to a desired level.

[0391] Furthermore, the structure of the electrode assembly 141 and the uncoated portion structure are not limited to the shown structures and can be replaced by the structures of the above embodiments (variations).

[0392] ​ is a cross-sectional view taken along the Y-axis of a cylindrical battery cell 180 according to another embodiment of the present disclosure.

[0393] Referring to ​ , in the structure of the electrode assembly 141, the cylindrical battery cell 180 is substantially the same as the ​ shown cylindrical battery cell 150, and the remaining configuration except for the electrode assembly 141 is substantially the same as the ​ shown cylindrical battery cell 170.

[0394] Therefore, the exemplary configurations (variations) of the cylindrical battery cells 150 and 170 can be equivalently applied to the cylindrical battery cell 180.

[0395] Furthermore, the structure of the electrode assembly 141 and the uncoated portion structure are not limited to the shown structures and can be replaced by the structures of the above embodiments (variations).

[0396] ​ is a cross-sectional view taken along the Y-axis of a cylindrical battery cell 190 according to another embodiment of the present disclosure.

[0397] Referring to ​ , the cylindrical battery cell 190 includes ​ the shown electrode assembly 110, and the remaining configuration except for the electrode assembly 110 is substantially the same as the ​ shown cylindrical battery cell 140.

[0398] Referring to ​, the uncoated portions 146a, 146b of the electrode assembly 110 are bent from the outer periphery toward the core. In this case, since the height of the uncoated portion B1 on the core side is lower than that of other regions, the uncoated portion B1 on the core side is substantially not bent. The first current collector plate 144 can be welded to the bent surface of the uncoated portion 146a, and the second current collector plate 145 can be welded to the bent surface of the uncoated portion 146b. When bending the uncoated portions 146a, 146b, the bent surfaces can be formed on the top and bottom of the electrode assembly 110 by multi-layer overlapping.

[0399] The electrode assembly 110 has a height of the uncoated portion B1 on the core side that is smaller than that of other regions. In addition, as ​ shown, the height H of the innermost uncoated portion in the middle uncoated portion B2 is equal to or less than the radial length R of the uncoated portion B1 on the core side. Therefore, when the uncoated portion 46a is bent toward the core, the cavity 112 at the core of the electrode assembly 110 can be opened upward without being blocked (see the dashed circle).

[0400] When the cavity 112 is not blocked, there is no difficulty in the electrolyte injection process, and the electrolyte solution injection efficiency is improved. In addition, by inserting the welding jig through the cavity 112, the welding process can be easily performed between the second current collector plate 145 and the battery can 142.

[0401] In the case where the uncoated portions 146a, 146b have a segmented structure, when adjusting the width and / or height and / or pitch of the segments to meet the numerical range of the above embodiments, the segmented multi-layers fully overlap to ensure the welding strength when the segments are bent and no blank space (gap) is formed on the bent surface.

[0402] The structure of the uncoated portions 146a, 146b can be changed to the structure of the above embodiments (variations) opposite to the shown structure. In addition, the present disclosure does not exclude applying a conventional uncoated portion structure to any one of the uncoated portions 146a, 146b.

[0403] ​ is a cross-sectional view taken along the Y-axis of a cylindrical battery cell 200 according to another embodiment of the present disclosure.

[0404] Referring to ​ , the cylindrical battery cell 200 includes ​ the electrode assembly 110 shown, and the remaining configuration except for the electrode assembly 110 is substantially the same as that of the ​ cylindrical battery cell 180 shown.

[0405] Referring to ​, the uncoated portions 146a, 146b of the electrode assembly 110 are bent from the outer periphery toward the core. In this case, since the height of the uncoated portion B1 on the core side is lower than that of other regions, the uncoated portion B1 on the core side is substantially not bent. The first current collector plate 144 is welded to the bent surface of the uncoated portion 146a, and the second current collector plate 176 can be welded to the bent surface of the uncoated portion 146b.

[0406] The electrode assembly 110 has a height of the uncoated portion B1 on the core side that is smaller than that of other regions. In addition, as ​ shown, the height H of the innermost uncoated portion in the intermediate uncoated portion B2 is equal to or less than the radial length R of the uncoated portion B1 on the core side. Therefore, when the uncoated portions 146a, 146b are bent toward the core, the cavity 112 at the core of the electrode assembly 110 can be opened upward without being blocked (see the dashed circle).

[0407] When the cavity 112 is not blocked, there is no difficulty in the electrolyte injection process, and the injection efficiency of the electrolyte solution is improved. In addition, by inserting the welding jig through the cavity 112, the welding process can be easily performed between the second current collector plate 176 and the battery can 171.

[0408] In the case where the uncoated portions 146a, 146b have a segmented structure, the width and / or height and / or pitch of the segments are adjusted to meet the numerical range of the above-described embodiments, and the segmented layers overlap sufficiently to ensure the welding strength when the segments are bent and no empty holes (gaps) are formed on the bent surface.

[0409] The structure of the uncoated portions 146a, 146b can be changed to the structure according to the above-described embodiments (variations) opposite to the shown structure. In addition, the present disclosure does not exclude applying a conventional uncoated portion structure to any one of the uncoated portions 146a, 146b.

[0410] ​ is a cross-sectional view taken along the Y-axis of a cylindrical battery cell 210 according to another embodiment of the present disclosure.

[0411] Referring to ​ , the cylindrical battery cell 210 includes ​ the electrode assembly 100 shown, and the remaining configuration except for the electrode assembly 100 is substantially the same as that of the ​ cylindrical battery cell 140 shown.

[0412] Preferably, the uncoated portions 146a, 146b of the electrode assembly 100 are bent from the outer periphery toward the core. In this case, since the height of the core-side uncoated portion B1 and the outer-periphery-side uncoated portion B3 of the uncoated portion 146a is lower than that of other regions, the core-side uncoated portion B1 and the outer-periphery-side uncoated portion B3 are substantially not bent. The same applies to the uncoated portion 146b. The first current collector plate 144 can be welded to the bent surface of the uncoated portion 146a, and the second current collector plate 145 can be welded to the bent surface of the uncoated portion 146b.

[0413] The height of the core-side uncoated portion B1 is lower than that of the intermediate uncoated portion B2. In addition, as ​ shown, the height H of the innermost uncoated portion in the intermediate uncoated portion B2 is equal to or less than the radial length R of the core-side uncoated portion B1.

[0414] Therefore, when the uncoated portions 146a, 146b are bent toward the core, the cavity 102 at the core of the electrode assembly 100 can be opened upward without being blocked (see the dashed circle).

[0415] When the cavity 102 is not blocked, the electrolyte injection process has no difficulty, and the electrolyte solution injection efficiency is improved. In addition, by inserting the welding jig through the cavity, the welding process can be easily performed between the second current collector plate 145 and the battery can 142.

[0416] In addition, the height of the outer-periphery-side uncoated portion B3 is lower than that of the intermediate uncoated portion B2. Therefore, when the uncoated portion 146a is bent, the outer-periphery-side uncoated portion B3 is substantially not bent. In addition, since the outer-periphery-side uncoated portion B3 is sufficiently spaced from the crimped portion 147, damage to the outer-periphery-side uncoated portion B3 during the crimping process of forming the crimped portion 147 can be prevented.

[0417] In the case where the uncoated portions 146a, 146b have a segmented structure, when the width and / or height and / or pitch of the segments are adjusted to meet the numerical range of the above-described embodiments, the segmented layers sufficiently overlap to ensure the welding strength when the segments are bent and no empty holes (gaps) are formed on the bent surface.

[0418] The structure of the uncoated portions 146a, 146b can be changed to the structure according to the above-described embodiments (variations) opposite to the shown structure. In addition, the present disclosure does not exclude applying a conventional uncoated portion structure to any one of the uncoated portions 146a, 146b.

[0419] ​ is a cross-sectional view taken along the Y-axis of a cylindrical battery cell 220 according to another embodiment of the present disclosure.

[0420] Refer to​ , the cylindrical battery cell 220 includes ​ the electrode assembly 100 shown, and the remaining configuration except for the electrode assembly 100 is substantially the same as that of ​ the cylindrical battery cell 180 shown.

[0421] Preferably, the uncoated portions 146a, 146b of the electrode assembly 100 are bent from the outer periphery toward the core. In this case, since the height of the core-side uncoated portion B1 of the uncoated portion 146a is lower than other regions, the core-side uncoated portion B1 is substantially not bent. The same applies to the uncoated portion 146b. The first current collector plate 144 can be welded to the bent surface of the uncoated portion 146a, and the second current collector plate 176 can be welded to the bent surface of the uncoated portion 146b.

[0422] The electrode assembly 100 has a core-side uncoated portion B1 with a height less than the height of the middle uncoated portion B2. Additionally, as ​ shown, the height H of the innermost uncoated portion in the middle uncoated portion B2 is equal to or less than the radial length R of the core-side uncoated portion B1. Thus, when the uncoated portion 146a is bent toward the core, the cavity 102 at the core of the electrode assembly 100 can be opened upward without being blocked (see the dashed circle).

[0423] When the cavity 102 is not blocked, there is no difficulty in the electrolyte injection process, and the electrolyte solution injection efficiency is improved. Additionally, by inserting the welding jig through the cavity 102, the welding process can be easily performed between the second current collector plate 176 and the battery can 171.

[0424] Furthermore, the height of the outer peripheral side uncoated portion B3 of the uncoated portion 146a is less than the height of the middle uncoated portion B2. Thus, when the uncoated portion 146a is bent, the outer peripheral side uncoated portion B3 is substantially not bent. The same applies to the uncoated portion 146b.

[0425] In the case where the uncoated portions 146a, 146b have a segmented structure, when the width and / or height and / or pitch of the segments are adjusted to meet the numerical range of the above-described embodiments, the segmented layers sufficiently overlap to ensure welding strength when the segments are bent and no empty holes (gaps) are formed on the bent surface.

[0426] The structure of the uncoated portions 146a, 146b can be changed to the structure according to the above-described embodiments (variations) opposite to the shown structure. Additionally, the present disclosure does not exclude applying a conventional uncoated portion structure to any one of the uncoated portions 146a, 146b.

[0427] The cylindrical battery cell according to the above-described embodiments (variations) can be used to manufacture a battery pack.

[0428] ​ is a diagram schematically showing a configuration of a battery pack according to an embodiment of the present disclosure.

[0429] Referring ​ , a battery pack 300 according to an embodiment of the present disclosure includes a group of cylindrical battery cells 301 electrically connected to each other and a battery pack housing 302 accommodating the group of cylindrical battery cells 301. The cylindrical battery cells 301 are any one of the battery cells according to the above-described embodiment (variant). In the drawings, for ease of explanation, components such as bus bars for electrical connection of the cylindrical battery cells 301, a cooling unit, and external terminals are omitted.

[0430] The battery pack 300 can be installed in a vehicle. The vehicle can be, for example, an electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. The vehicle includes a four-wheel vehicle or a two-wheel vehicle.

[0431] ​ is a diagram showing a vehicle including ​ the battery pack 300.

[0432] Referring ​ , a vehicle V according to an embodiment of the present disclosure includes a battery pack 300 according to an embodiment of the present disclosure. According to an embodiment of the present disclosure, the vehicle V is operated by electric power supplied from the battery pack 300.

[0433] According to the present disclosure, using uncoated portions protruding from the upper and lower portions of the electrode assembly as electrode joints can reduce the internal resistance of the cylindrical battery cell and increase the energy density.

[0434] According to another aspect of the present disclosure, an improved uncoated portion structure of the electrode assembly can prevent interference between the electrode assembly and the inner peripheral surface of the battery can during the process of forming the curled portion of the battery can, thereby preventing an internal short circuit of the cylindrical battery cell that may occur due to partial deformation of the electrode assembly.

[0435] According to another aspect of the present disclosure, an improved uncoated portion structure of the electrode assembly can prevent the uncoated portion near the slotted valley from tearing when the uncoated portion is bent, and sufficiently increase the number of overlapping layers of the uncoated portion, thereby causing improved welding strength.

[0436] According to another aspect of the present disclosure, an improved uncoated portion structure adjacent to the core of the electrode assembly can prevent the cavity at the core of the electrode assembly from being blocked when the uncoated portion is bent, making it easy to perform the electrolyte solution injection process and the welding process between the battery can and the current collector plate.

[0437] According to another aspect of the present disclosure, a cylindrical battery cell having a structure for achieving a low internal resistance, preventing an internal short circuit, and improving the welding strength of a current collector plate and an uncoated portion, a battery pack including the cylindrical battery cell, and a vehicle can be provided.

[0438] Although the present disclosure has been described above with respect to a limited number of embodiments and drawings, the present disclosure is not limited thereto, and it is obvious that those skilled in the art can make various changes and modifications within the scope of the technical aspects of the present disclosure and the appended claims and their equivalents.

[0439] ​

[0440] ​

[0441] ​

[0442] As shown in [Table 1] below, a metal foil (thickness 15 μm) (e.g., aluminum) for a current collector is prepared, including an uncoated portion where a Group 1 segment and a Group 2 segment will be formed.

[0443] In the metal foil, the length in the winding direction from the core to the outer periphery is (B1 + B2 + B3) 4,000 mm, and the width in the winding axis direction is 75 mm. The metal foil includes a core-side uncoated portion B1, an outer-periphery-side uncoated portion B3, and an intermediate uncoated portion B2 between the core-side portion and the outer-periphery-side portion. The length of B1 is 350 mm, the length of B2 is 3500 mm, and the length of B3 is 150 mm.

[0444] A predetermined width of the metal foil inward from the second side in the width direction is defined as a positive electrode active material portion, and the remaining portion is defined as an uncoated portion or a first portion, and the heights of the core-side uncoated portion and the outer-periphery-side uncoated portion in the winding axis direction are less than the height of the intermediate uncoated portion.

[0445] ​

[0446] The negative electrode current collector is prepared in the same manner as the positive electrode current collector, except that a copper foil (thickness 10 μm) is used as the current collector and the width in the winding axis direction is 80 mm.

[0447] [Table 1]

[0448]

[0449] ​

[0450] The average particle size (D 50) Earthen natural graphite with a size of 11 μm, carbon black, carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBR) are mixed with water at a weight ratio of 94:1.5:2:2.5 to prepare a slurry for the negative electrode active material portion, such that the concentration of the remaining components except water is 50 wt%. Subsequently, the slurry is coated on the surface of the prepared copper current collector for the negative electrode active material portion using a slot die at a traveling speed of 40 m / min. Based on the winding axis direction, the width of the negative electrode active material portion is 70 mm, and the width of the uncoated portion is 10 mm. Based on the electrode area, the loading amount of the negative electrode active material is 16 mg / cm 2 . The copper foil coated with the slurry for the negative electrode active material portion is dried while passing through a 60 m long hot air oven, and in this case, the temperature of the oven is adjusted to maintain 130 °C. Subsequently, roll pressing is performed to a target thickness of 180 μm to obtain a negative electrode with a density of 3.45 g / cc.

[0451] Subsequently, the middle uncoated portion is divided into multiple segments by laser slitting to meet the requirements of Table 1 below. In this case, the lower ends of the slitting valleys of each segment are adjusted to have substantially the same height.

[0452] ​

[0453] Li(Ni 0.6 Mn 0.2 Co 0.2 )O2 (NCM-622) as the positive electrode active material, carbon black as the conductive material, and polyvinylidene fluoride (PVdF) as the binder are added to water as the dispersion medium at a weight ratio of 96:2:2 to prepare a positive electrode active material slurry. The slurry is coated on the surface of the prepared aluminum current collector and dried and rolled under the same conditions as the negative electrode to manufacture a positive electrode. In the positive electrode, based on the winding axis direction, the width of the positive electrode active material portion is 65 mm, and the width of the uncoated portion is 10 mm.

[0454] In this case, considering the theoretical discharge capacity of NMC 622, the positive electrode active material portion is adjusted such that the NP ratio of the battery is 1.18 (118%, approximately 〈0000107〉27.7 cm 2 ).

[0455] Subsequently, the middle uncoated portion is divided into multiple segments by laser slitting to meet the requirements in Table 1 below. In this case, the lower ends of the slitting valleys of each segment are adjusted to have substantially the same height.

[0456] ​

[0457] About 5wt% of polyvinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP) polymer is added to tetrahydrofuran (THF) and dissolved at 50°C for about 12 hours or longer to prepare a polymer solution. BaTiO3 powder with a particle size of about 400nm is added to the polymer solution with a total solid of 20wt% and dispersed to prepare a mixture solution (BaTiO3 / PVdF-HFP=80:20 (weight ratio)). The mixture solution is coated on both surfaces of a polypropylene substrate using a doctor blade method. After coating, THF is dried to obtain a final organic / inorganic composite porous diaphragm. The thickness of the final diaphragm is about 30μm. As measured with a porometer, the final organic / inorganic composite porous diaphragm has a pore size of 0.4μm and a porosity of 60%.

[0458] ​

[0459] The prepared negative electrode, separator, and positive electrode are stacked and wound in this order to produce a jellyroll-type electrode assembly. ​ The structures shown in FIG are stacked, and the comparative example is ​ In the example, L1 is 2.5 mm, and L2 is 1.5 mm. In the comparative example, the positive electrode, the negative electrode, and the separator are arranged so that the surface of the negative electrode active material part and the positive electrode active material part are covered by the separator. ​ It was confirmed that the lengths from both ends of the top / bottom of the electrode assembly to the end of the separator were approximately 1.0 mm and 1.5 mm, respectively.

[0460] ​

[0461] The exposed segments 1 to 7 at the upper and lower portions of the electrode assembly are bent toward the core, and the positive and negative current collecting plates are welded to the upper and lower bent surfaces, respectively. ​A cylindrical battery cell of the structure shown. That is, an electrode assembly including a welded positive current collector plate and a welded negative current collector plate is inserted into a battery case in which external terminals are pre-installed, the positive current collector plate is welded to the external terminals, and the edge of the negative current collector plate is welded to the crimped portion. Subsequently, the battery case is placed upright in the chamber of an electrolyte injector, where the opening portion of the battery case faces the direction opposite to gravity. Subsequently, 1.0 M LiPF6 is dissolved in an organic solvent in which ethylene carbonate (EC), dimethyl carbonate (DMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:2:1 to prepare a non-aqueous electrolyte solution. Subsequently, the electrolyte solution is injected through the opening portion of the battery case, the pressure of the chamber is increased to 800 kPa within 20 seconds and maintained for 150 seconds, then the pressure of the chamber is reduced to -90 kPa within 20 seconds and the chamber is maintained in a substantially vacuum state for 20 seconds. After the electrolyte solution filling process is completed, the opening portion of the battery case is sealed using a gasket through a sealing body to complete the manufacture of the cylindrical battery cell.

[0462] The above manufacturing method is basically equally applicable to manufacturing the batteries of the comparative examples.

[0463] ​

[0464] Disassemble the batteries of each of the examples and comparative examples to obtain the positive and negative electrodes. Subsequently, each of the negative and positive electrodes is cut into samples with a size of 10 cm at a total of nine points. 2 The nine samples include three samples (#1 to #3) obtained from the region near the core of the electrode assembly based on the winding direction when the electrode is unwound, three samples (#7 to #9) obtained from the region near the outer periphery of the electrode assembly, and three samples (#4 to #6) obtained from the central region of the electrode. And when collecting every three samples from each sample collection region, each sample is obtained from the lower end, the center, and the upper end of the active material layer in the winding axis direction. In addition, #1, #4, and #7 indicate the regions near one end of the electrode in the width direction, #3, #6, and #9 indicate the regions near the other end of the electrode in the width direction, and #2, #5, and #8 indicate the intermediate regions. ​ Shows the positions where the samples are obtained. In this case, ​ Shows based on ​ the positions where the samples are obtained, and the above [Table 1] shows the shapes or numerical values of the samples.

[0465] The amount of the filled electrolyte is determined by measuring the weight of the sample filled with the electrolyte solution, washing each sample with dimethyl carbonate (DMC), drying at 150 °C, measuring the weight of the dried sample, and calculating the weight difference before and after filling.

[0466] For each of #1 to #9 in the positive electrode of the example, the filled electrolyte amount was 21.7 mg, and that of the comparative example was 20.7 mg. In addition, the average amount of the electrolyte filled in #1 to #9 of the negative electrode of the example was 35.6 mg, and that of the comparative example was 33.2 mg.

[0467] Therefore, it was confirmed that the electrode assembly of the example having the features of the present disclosure exhibited better electrolyte wetting than the comparative example.

[0468] [Table 2]

[0469]

[0470] ​

[0471] The capacity retention rate was evaluated using the batteries fabricated in the examples and comparative examples. To measure the life characteristics and capacity retention rate of each battery, constant current charging up to 4.25 V at 1.0 C was performed from the first cycle to the 100th cycle, and constant current discharging up to 2.5 V was performed. In the present disclosure, the capacity retention rate can be defined by Equation 1 below.

[0472] [Equation 1]

[0473] Capacity retention rate (%) = [Discharge capacity at the 100th cycle / Discharge capacity at the first cycle] X 100

[0474] ​ is a graph showing a comparison of the battery capacities between the batteries of the examples and comparative examples. Referring to ​ , the battery according to the present disclosure exhibits electrical and chemical properties superior to those of a battery having conventional structural features such as in the comparative example. In ​ , the solid line indicates the battery of the example, and the dashed line indicates the battery of the comparative example. Therefore, it was confirmed that the battery according to the present disclosure is advantageous for improving stability as compared with the related art because the electrochemical performance does not deteriorate and there is little or no damage to the separator when fabricating the electrode assembly.

Claims

1. An electrode assembly, the electrode assembly comprising: A first electrode plate, a second electrode plate, and a separator between the first electrode plate and the second electrode plate, wherein the first electrode plate is a positive electrode plate and the second electrode plate is a negative electrode plate, or the first electrode plate is a negative electrode plate and the second electrode plate is a positive electrode plate, wherein each of the first electrode plate, the second electrode plate, and the separator independently has a strip shape with an aspect ratio greater than 1, and the first electrode plate, the second electrode plate, and the separator are stacked such that their respective length directions are parallel to each other, wherein each of the first electrode plate, the second electrode plate, and the separator independently has a first side and a second side, wherein the first side is the first end in the thickness direction, and the second side is the second end disposed at a position opposite to the first side, wherein the first electrode plate and the second electrode plate include a first portion and a second portion on at least one side surface, the first portion is an electrode active material portion coated with an electrode active material and extends from the second side toward the first side, and the second portion is an uncoated portion not coated with an electrode active material and extends from the first side toward the second side to the electrode active material portion, wherein in the electrode assembly, the first sides of the first electrode plate and the second electrode plate are arranged facing in opposite directions, and wherein in the electrode assembly, the first side of the separator protrudes beyond the second side of the first electrode plate and is disposed on the electrode active material portion of the second electrode plate, and the second side of the separator protrudes beyond the second side of the second electrode plate and is disposed on the uncoated portion of the first electrode plate.

2. The electrode assembly according to claim 1, wherein, The second electrode plate is a negative electrode plate.

3. The electrode assembly according to claim 1, wherein, Based on the width direction, the width of the electrode active material portion of the first electrode plate is narrower than the width of the electrode active material portion of the second electrode plate, and the two ends of the electrode active material portion of the first electrode plate in the width direction are disposed between the two ends of the electrode active material portion of the second electrode plate in the width direction.

4. The electrode assembly according to claim 1, wherein, At least a portion of the uncoated portion of at least one of the first electrode plate and the second electrode plate is divided into a plurality of segments by cutting grooves with a predetermined depth.

5. The electrode assembly according to claim 4, wherein, Each of the plurality of segments has a quadrilateral, trapezoidal, triangular, parallelogram, semi-circular, semi-ovoid, or semi-elliptical structure.

6. The electrode assembly according to claim 5, wherein, The first electrode plate has a first electrode plate segment, and wherein the separator is disposed to cover the grooved valley of the cutting groove of the segment.

7. The electrode assembly according to claim 1, wherein, The electrode assembly has a plurality of winding turns by winding the first electrode plate, the second electrode plate, and the separator around an axis in the length direction.

8. The electrode assembly according to claim 6, wherein, The electrode assembly has a plurality of winding turns by winding the first electrode plate, the second electrode plate, and the separator around an axis in the length direction, and wherein all or at least some of the segments are bent radially with respect to the axis at a bending point, wherein the bending point is any point within the segment.

9. The electrode assembly according to claim 8, wherein, The second side of the separator is disposed on the uncoated portion of the first electrode plate and is interposed between the electrode active material portion and the bending point.

10. The electrode assembly according to claim 9, wherein, The bending point is spaced apart from the second side of the separator by 0.1 mm or more.

11. The electrode assembly according to claim 1, wherein, The uncoated portion of at least one of the first electrode plate and the second electrode plate includes a core-side uncoated portion adjacent to the core of the electrode assembly, an outer-periphery-side uncoated portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate uncoated portion between the core-side uncoated portion and the outer-periphery-side uncoated portion. Wherein at least one of the core-side uncoated portion and the outer-periphery-side uncoated portion has a shorter distance from the electrode active material portion to the first side than the intermediate uncoated portion, and Wherein the electrode active material portion has a constant width in the thickness direction from the core side to the outer periphery side.

12. The electrode assembly according to claim 1, wherein, The uncoated portion of at least one of the first electrode plate and the second electrode plate includes a core-side uncoated portion adjacent to the core of the electrode assembly, an outer-periphery-side uncoated portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate uncoated portion between the core-side uncoated portion and the outer-periphery-side uncoated portion. Wherein the core-side uncoated portion has a shorter distance from the electrode active material portion to the first side than the intermediate uncoated portion and the outer-periphery-side uncoated portion, and Wherein the electrode active material portion has a constant width in the thickness direction from the core side to the outer periphery side.

13. The electrode assembly according to claim 11 or 12, wherein, The core-side uncoated portion includes an uncoated portion of the electrode plate portion corresponding to the innermost wound turn of the electrode assembly, and the outer-periphery-side uncoated portion includes an uncoated portion of the electrode plate portion corresponding to the outermost wound turn of the electrode assembly.

14. The electrode assembly according to claim 12, wherein, All or at least a part of the intermediate uncoated portion is divided into a plurality of segments.

15. The electrode assembly according to claim 11 or 12, wherein, At least a part of the intermediate uncoated portion has a height that gradually increases in the winding axis direction from the core side toward the outer periphery side.

16. The electrode assembly according to claim 4, wherein, The slotted valley of each segment and the electrode active material portion are spaced apart from each other by a predetermined distance.

17. The electrode assembly according to claim 1, wherein, The separator includes a porous polymer substrate; and a porous coating on at least one surface of the porous polymer substrate, the porous coating including inorganic particles and a binder polymer.

18. The electrode assembly according to claim 17, wherein, The inorganic particles include inorganic particles having hydrophilicity on the surface.

19. A cylindrical battery cell, the cylindrical battery cell comprising: The electrode assembly according to any one of claims 1 to 18; A battery can that houses the electrode assembly and is electrically connected to one of the first electrode plate and the second electrode plate, the battery can being of a first polarity; A sealing body for sealing an open end of the battery can; And A terminal that is electrically connected to the other of the first electrode plate and the second electrode plate and has an exposed surface, the terminal being of a second polarity.

20. A battery pack, the battery pack including at least one battery cell according to claim 19.

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