Electrode assembly, cylindrical battery cell, battery pack including the same, and automobile

Abstract

Disclosed are an electrode assembly, a cylindrical battery cell, a battery pack including the same, and an automobile. The electrode assembly is a jelly-roll type electrode assembly having a structure in which a first electrode plate and a second electrode plate in a sheet shape and a separator film interposed therebetween are wound in one direction. At least one of the first electrode plate and the second electrode plate includes an uncoated portion in which an active material layer is not coated at a long side end portion. At least a portion of the uncoated portion can be used as an electrode tab by itself. In addition, the uncoated portion includes a core portion side uncoated portion adjacent to a core portion of the electrode assembly, a peripheral side uncoated portion adjacent to an outer peripheral surface of the electrode assembly, and an intermediate uncoated portion interposed between the core portion side uncoated portion and the peripheral side uncoated portion. It is preferable that at least one of the core portion side uncoated portion and the peripheral side uncoated portion has a relatively lower height in a winding axis direction than the intermediate uncoated portion.

Description

Technical Field

[0001] This invention relates to electrode assemblies, cylindrical battery cells, battery packs including the same, and automobiles. Background Technology

[0002] Secondary batteries, which are highly adaptable to various product groups and have high energy density and other electrical properties, are not only used in portable devices, but also widely used in electric vehicles (EVs) or hybrid electric vehicles (HEVs) driven by electric power sources.

[0003] Such secondary batteries not only have the primary advantage of significantly reducing the use of fossil fuels, but also have the advantage of producing no byproducts when using energy. Therefore, they are attracting much attention as a new energy source that is both environmentally friendly and improves energy efficiency.

[0004] Currently, widely used rechargeable batteries include lithium-ion batteries, lithium polymer batteries, nickel-cadmium batteries, nickel-metal hydride batteries, and nickel-zinc batteries. The operating voltage of a single rechargeable battery cell is approximately 2.5V to 4.5V. Therefore, when a higher output voltage is required, multiple batteries are connected in series to form a battery pack. Additionally, depending on the required charge / discharge capacity of the battery pack, multiple battery cells are sometimes connected in parallel to form a battery pack. Therefore, the number of battery cells and the electrical connection configuration within the aforementioned battery packs are varied depending on the required output voltage and / or charge / discharge capacity.

[0005] On the other hand, as types of secondary battery cells, there are cylindrical, square, and pouch-shaped batteries. In the case of a cylindrical battery cell, an electrode assembly in the form of a gel roll is formed by sandwiching an insulator, i.e., a separator, between the anode and cathode, and then inserting it into the battery casing to form a battery. Furthermore, strip-shaped electrode tabs are connected to the uncoated portions of both the anode and cathode, electrically connecting the electrode assembly to the exposed electrode terminals. For reference, the anode electrode terminal is a cover plate of a sealing body that seals the opening of the battery can, and the cathode electrode terminal is the battery can itself. However, according to conventional cylindrical battery cells with such a structure, the current is concentrated on the strip-shaped electrode tabs connected to the uncoated portions of the anode and / or cathode, resulting in high resistance, excessive heat generation, and poor current collection efficiency.

[0006] In small cylindrical battery cells with form factors of 18650 or 21700, resistance and heat generation are not major issues. However, when the form factor is increased to make the cylindrical battery cells suitable for electric vehicles, more heat is generated around the electrode tabs during rapid charging, leading to the possibility of the cylindrical battery cells catching fire.

[0007] To address this problem, a cylindrical battery (so-called tabless cylindrical battery cell) with the following structure is disclosed: an uncoated anode portion and an uncoated cathode portion are respectively provided at the upper and lower ends of a gel roll-type electrode assembly, and a current collector plate is welded to such uncoated portions to improve current collection efficiency.

[0008] Figures 1 to 3 This is a diagram illustrating the manufacturing process of a tabless cylindrical battery. Figure 1 The structure of the electrode plate is shown. Figure 2 The electrode plate winding process is shown. Figure 3 The process of welding a current collector to the bent surface of the uncoated part is shown.

[0009] Reference Figures 1 to 3 The anode plate 10 and the cathode plate 11 have a structure in which an active material 21 is coated on the sheet-like current collector 20, and an uncoated portion 22 is included on one long side along the winding direction X.

[0010] like Figure 2 As shown, electrode assembly A is manufactured by sequentially stacking the anode plate 10 and the cathode plate 11 together with two separation membranes 12 and then winding them in one direction X. At this time, the uncoated portions of the anode plate 10 and the cathode plate 11 are arranged in opposite directions to each other.

[0011] After the winding process, the uncoated portion 10a of the anode plate 10 and the uncoated portion 11a of the cathode plate 11 are bent toward the core. Then, current collectors 30 and 31 are welded to the uncoated portions 10a and 11a respectively to form a bond.

[0012] The uncoated anode portion 10a and the uncoated cathode portion 11a are not attached to additional electrode tabs. The current collectors 30 and 31 are connected to external electrode terminals. The current path is formed with a large cross-sectional area along the winding axis of the electrode assembly A (refer to the arrow), thus reducing the resistance of the battery cell. This is because resistance is inversely proportional to the cross-sectional area of ​​the current flow path.

[0013] In tabless cylindrical batteries, in order to improve the welding characteristics of uncoated portions 10a and 11a and current collectors 30 and 31, strong pressure is applied to the welding positions of uncoated portions 10a and 11a to bend the uncoated portions 10a and 11a in a flat manner as much as possible.

[0014] However, when bending the welding positions of the uncoated portions 10a and 11a, the uncoated portions 10a and 11a become irregularly skewed and deformed. In this case, the deformed portion comes into contact with an electrode of opposite polarity, causing an internal short circuit or fine cracks in the uncoated portions 10a and 11a. Furthermore, as the uncoated portion 32 adjacent to the core of electrode assembly A is bent, the cavity 33 located in the core of electrode assembly A is completely or partially blocked. In this case, problems arise during the electrolyte injection process. That is, the cavity 33 located in the core of electrode assembly A is used as a channel for injecting electrolyte. However, when this channel is blocked, it is difficult to inject electrolyte. Additionally, during the insertion of the electrolyte injector into the cavity 33, interference occurs between it and the uncoated portions 32 surrounding the core, resulting in the uncoated portions 32 being torn.

[0015] Furthermore, the bent portions of the uncoated parts 10a and 11a of the current collectors 30 and 31 need to be overlapped into multiple layers, and there should be no empty spaces (gaps). Only in this way can sufficient welding strength be obtained, and even when using the latest technologies such as laser welding, the problem of laser penetration into the interior of electrode assembly A and dissolving or evaporating the separation membrane or active material can be prevented.

[0016] Furthermore, conventional tabless cylindrical battery cells have an uncoated anode portion 10a formed entirely on the upper part of the electrode assembly A. Therefore, when the outer periphery of the upper end of the battery can is pressed inward to form a rolled edge, the upper edge region 34 of the electrode assembly A is subjected to pressure applied through the battery can. This pressure causes partial deformation of the electrode assembly A, at which point the separation membrane 12 is torn, resulting in an internal short circuit. An internal short circuit in the battery can cause it to overheat or explode.

[0017] Previous separation membranes incorporated coatings containing inorganic particles to improve the thermal shrinkage properties of porous polymer substrates. However, these were single-sided inorganic-coated separation membranes, with the coating applied only to one side of the porous polymer substrate. When such inorganic-coated separation membranes are positioned opposite the electrodes within the gel roll (J / R), one side is a fabric layer and the other side is an inorganic (ceramic) coating, resulting in asymmetrical electrolyte impregnation characteristics. This asymmetry in electrolyte impregnation leads to management challenges in designing the anode and cathode to match the separation membrane. Increased pressure / vacuum conditions are required when impregnating the electrolyte within the gel roll, increasing costs. Furthermore, inappropriate impregnation processes can result in performance degradation.

[0018] Furthermore, in the conventional case of single-sided inorganic coating of the separation membrane, one side of the membrane fabric is exposed, thus limiting its heat resistance. This results in significant shrinkage at temperatures above 130°C, posing a major problem. Consequently, under thermal shock (above 130°C), the shrinkage of the separation membrane can cause short circuits in the internal electrodes, increasing the risk of fire due to abnormal reactions (overcharging, external short circuits) as the internal temperature rises.

[0019] Furthermore, in the case of ungrooved gel rolls, after assembly, the current collector (i.e., foil folding) forms a closed structure both internally and externally. This interferes with the movement of the electrolyte towards the electrodes within the gel roll during liquid injection, resulting in uneven electrolyte impregnation characteristics. This is due to the uneven electrolyte impregnation path during impregnation. Consequently, the decreased impregnation uniformity leads to increased deviations between cells, forming an unstable solid electrolyte interphase (SEI) layer and causing increased resistance distribution. Summary of the Invention

[0020] The problem that the invention aims to solve

[0021] The present invention was developed under the prior art background described above, and the purpose of the present invention is to provide an electrode assembly with improved electrolyte impregnation characteristics.

[0022] Another technical objective of the present invention is to provide an electrode assembly having an improved uncoated portion structure in which stress pressure applied to the uncoated portion is relieved when the uncoated portion exposed at both ends of the electrode assembly is bent.

[0023] Another technical challenge of the present invention is to provide an electrode assembly that does not block the electrolyte injection channel even when the uncoated portion is bent.

[0024] Another technical challenge of the present invention is to provide an electrode assembly having the following structure: when the upper edge of the battery can is rolled up, the upper edge of the electrode assembly can be prevented from contacting the inner surface of the battery can.

[0025] Another technical challenge of the present invention is to provide an electrode assembly that increases energy density and reduces resistance.

[0026] Another technical challenge of the present invention is to provide a cylindrical battery cell including an electrode assembly with an improved structure, a battery pack including the same, and a vehicle including the battery pack.

[0027] The technical problems to be solved by the present invention are not limited to those described above. Those skilled in the art can clearly understand other problems not mentioned herein from the following description of the invention.

[0028] Methods for solving problems

[0029] This invention relates to electrode assemblies for electrochemical devices. A first aspect of the invention provides the electrode assembly comprising a first electrode plate, a second electrode plate, and a separation membrane sandwiched therebetween. The first electrode plate, the second electrode plate, and the separation membrane are wound in one direction around an axis, forming a plurality of turns. The electrode assembly is characterized in that the first electrode plate and the second electrode plate each independently include a first side portion and a second side portion, the first side portion and the second side portion being arranged opposite each other in the axial direction. The first electrode plate and the second electrode plate each independently include a first portion and a second portion on at least one surface. The first portion is an electrode active material portion coated with an electrode active material, and... The second side extends toward the first side, and the second part is an uncoated part without electrode active material, extending from the first side toward the second side to the electrode active material part of the first part. At least a portion of the uncoated part is divided into multiple segments by a cut groove of a predetermined depth. Each segment has a first end that is consistent with the first side. All or at least a portion of the segments are bent radially relative to the axis at a bending position. The bending position is any position within the segment below the first end. The end of any side of the separation membrane is located between the bending position of each segment and the boundary line of the first and second parts.

[0030] In a second aspect of the invention, in the first aspect described above, the separation membrane is characterized in that either end of the separation membrane is located between the bending position and the boundary line of the first and second portions, and the separation membrane is configured in such a way that the groove of the cut groove is not exposed.

[0031] In a third aspect of the invention, in the first aspect described above, the bending position is any position between the first end and the reference line, and the reference line is a straight line extending in the winding direction (X) at a height corresponding to the groove of the cutting groove.

[0032] In a fourth aspect of the present invention, in addition to the third aspect described above, the first electrode plate and the second electrode plate have different distances from the reference line to the first end along the winding direction.

[0033] In a fifth aspect of the present invention, in the third or fourth aspect described above, the adjacent winding segments of the bent segments continuously overlap in the radial direction or the opposite direction to form a surface region at the upper or lower end of the winding axis in the direction of the electrode assembly. When the shortest distance between the highest point in the surface region and the reference line is taken as the height (Has) of the surface region, the end of either side of the separation membrane is positioned relative to the reference line and within 90% of the height (Has) of the surface region in the first side direction of the electrode assembly or in the second side direction of the electrode assembly below the reference line.

[0034] A sixth aspect of the present invention, in any one of the first to fifth aspects, is characterized in that the uncoated portion includes a core-side uncoated portion adjacent to the core of the electrode assembly, an outer peripheral-side uncoated portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate uncoated portion sandwiched between the core-side uncoated portion and the outer peripheral-side uncoated portion, wherein at least one of the core-side uncoated portion and the outer peripheral-side uncoated portion is relatively smaller in distance from the reference line and the first side portion compared to the intermediate uncoated portion.

[0035] A seventh aspect of the present invention, in any one of the first to sixth aspects, is characterized in that the distance from the core-side uncoated portion to the reference line and the first side portion is relatively smaller compared to the intermediate uncoated portion and the outer peripheral uncoated portion.

[0036] The eighth aspect of the present invention, in the sixth or seventh aspect described above, is characterized in that the height of the uncoated portion on the core side is consistent with the reference line.

[0037] A ninth aspect of the present invention, in any one of the sixth to eighth aspects, is characterized in that the uncoated portion on the core side includes an uncoated portion of the electrode plate portion corresponding to the innermost winding of the electrode assembly, and the uncoated portion on the outer periphery side includes an uncoated portion of the electrode plate portion corresponding to the outermost winding of the electrode assembly.

[0038] The tenth aspect of the present invention, in any one of the sixth to ninth aspects, is characterized in that all or at least a portion of the intermediate uncoated portion is divided into a plurality of segments.

[0039] In an eleventh aspect of the present invention, in any one of the first to tenth aspects described above, the bending position is separated from the separation membrane by 0.1 mm or more.

[0040] The twelfth aspect of the present invention, in any one of the first to eleventh aspects described above, is characterized in that:

[0041] The end of either side of the separation membrane is located between the aforementioned bend position and the baseline or below the baseline, which is a straight line extending in the winding direction (X) at a height corresponding to the groove of the slit groove that divides the multiple sections.

[0042] In a thirteenth aspect of the present invention, in addition to the twelfth aspect described above, the bent section among the aforementioned sections is referred to as a bent section. Relative to the smallest bent section having the smallest height among the aforementioned bent sections, the end of the separation membrane in the width direction is positioned on the outer side of the electrode assembly with reference to a reference line and at less than 50% of the height of the smallest bent section, or the end of the separation membrane in the width direction is positioned on the inner side of the electrode assembly with reference to a reference line and at less than 30% of the height of the smallest bent section. The reference line is a straight line extending in the winding direction (X) at a height corresponding to the groove of the cutting groove.

[0043] The fourteenth aspect of the present invention, in addition to the thirteenth aspect, is characterized in that the distance from the first end of the minimum bending section to the reference line is 2 mm or more.

[0044] In a fifteenth aspect of the present invention, in the thirteenth or fourteenth aspect described above, the electrode assembly further includes a segment A, which has a height smaller than the minimum bending segment, or excludes a segment with a height smaller than the minimum bending segment, wherein the minimum bending segment is the minimum segment, and the height of the segment refers to the shortest distance from the baseline to the first end of the segment.

[0045] The sixteenth aspect of the present invention, in any one of the sixth to fifteenth aspects, is characterized in that at least a portion of the intermediate uncoated portion increases in height in the winding axis direction from the core side toward the outer periphery side in stages.

[0046] The seventeenth aspect of the present invention, in any one of the first to sixteenth aspects described above, is characterized in that at least one of the height in the winding axis direction and the width in the winding direction of the plurality of segments increases individually or according to each group, as the segments move from the core side toward the outer periphery side.

[0047] The eighteenth aspect of the present invention, in any one of the first to seventeenth aspects, is characterized in that the plurality of slits respectively satisfy at least one of the following conditions: a width condition of 1 mm to 6 mm in the winding direction; a height condition of 2 mm to 10 mm in the winding shaft direction; and a spacing condition of 0.05 mm to 1 mm in the winding direction.

[0048] The nineteenth aspect of the present invention, in any one of the first to eighteenth aspects, is characterized in that the plurality of segments satisfy a spacing condition of 0.05 mm to 1 mm in the winding direction, the spacing being determined according to the distance between the corners of two adjacent segments, and a chamfered reinforcement is added to the corner portion of the adjacent segments.

[0049] The twentieth aspect of the present invention, in any one of the first to nineteenth aspects described above, is characterized in that:

[0050] The above separation membrane includes:

[0051] Porous polymer substrates; and

[0052] A porous coating is located on at least one side of the aforementioned porous polymer substrate and comprises inorganic particles and adhesive polymers.

[0053] In a twenty-first aspect of the present invention, the inorganic particles described above are characterized in that the inorganic particles include inorganic particles with hydrophilic properties on their surface.

[0054] A twenty-second aspect of the present invention provides a cylindrical battery cell, characterized in that it comprises:

[0055] Electrode assembly according to any one of the first to twenty-first aspects;

[0056] A battery can housing the aforementioned electrode assembly, which is electrically connected to one of the aforementioned first electrode plate and the aforementioned second electrode plate and has a first polarity;

[0057] A sealing body that seals the open end of the aforementioned battery can; and

[0058] A terminal, which is electrically connected to another of the first electrode plate and the second electrode plate, has its surface exposed to the outside and has a second polarity.

[0059] The above-mentioned separation membrane has the following features:

[0060] Porous polymer substrates; and

[0061] A porous coating is located on both sides of the aforementioned porous polymer substrate and includes inorganic particles and adhesive polymers.

[0062] The twenty-third aspect of the present invention provides a battery pack, characterized in that it includes at least one battery cell as described in the twenty-second aspect.

[0063] The twenty-fourth aspect of the present invention provides an automobile, characterized in that it includes at least one battery pack as described in the twenty-third aspect.

[0064] Invention Effects

[0065] According to one aspect of the invention, the uncoated portions protruding from the upper and lower parts of the electrode assembly are themselves used as electrode tabs, thereby reducing the internal resistance of the battery cell and increasing the energy density.

[0066] According to another aspect of the invention, the structure of the uncoated portion of the electrode assembly is improved to prevent interference between the inner circumferential surface of the electrode assembly and the battery can during the formation of the rolled edge portion of the battery can, thereby preventing short circuits inside the cylindrical battery cell caused by partial deformation of the electrode assembly.

[0067] According to another aspect of the invention, the structure of the uncoated portion of the electrode assembly is improved to prevent the uncoated portion from tearing when bent, and the number of overlapping layers of the uncoated portion is sufficiently increased to improve the welding strength.

[0068] According to another aspect of the invention, the structure of the uncoated portion adjacent to the core of the electrode assembly is improved to prevent the cavity in the core of the electrode assembly from being blocked when the uncoated portion is bent, thereby enabling easy electrolyte injection and welding of the battery can and current collector.

[0069] According to another aspect of the present invention, a cylindrical battery cell having a structure that provides low internal resistance, prevents internal short circuits, and improves the welding strength of the current collector and the uncoated portion, a battery pack including the same, and an automobile are provided.

[0070] Furthermore, the present invention has various other effects, which will be described in the various embodiments or in relation to effects that can be easily derived by those skilled in the art, and such descriptions are omitted. Attached Figure Description

[0071] The accompanying drawings, which are attached to this specification, are used to illustrate preferred embodiments of the invention and, together with the embodiments described below, help to understand the technical concept of the invention. Therefore, the invention should not be interpreted in a way that is not limited to the matters shown in the drawings.

[0072] Figure 1 This is a top view showing the structure of the electrode plates used in the manufacture of conventional tabless cylindrical battery cells.

[0073] Figure 2 This diagram illustrates the electrode plate winding process of a conventional tabless cylindrical battery cell.

[0074] Figure 3 This illustrates the process of welding a current collector to the bent surface of the uncoated portion in a conventional tabless cylindrical battery cell.

[0075] Figure 4 This is a top view showing the structure of the electrode plate according to the first embodiment of the present invention.

[0076] Figure 5 This is a top view of the structure of the electrode plate according to the second embodiment of the present invention.

[0077] Figure 6This is a top view of the structure of the electrode plate according to the third embodiment of the present invention.

[0078] Figure 7a This is a top view of the structure of the electrode plate according to the fourth embodiment of the present invention. Figure 7b and Figure 7c This is a magnified view showing the cut-off portion in more detail.

[0079] Figure 8 This is a diagram illustrating the definitions of the slice width, height, and spacing of an embodiment of the present invention.

[0080] Figure 9a This is a top view showing the structure of the electrode plate according to the fifth embodiment of the present invention. Figure 9b and Figure 9c This is a magnified view showing the cut-off portion in more detail.

[0081] Figure 10 This is a diagram illustrating the definitions of the slice width, height, and spacing of an embodiment of the present invention.

[0082] Figure 11 It is a cross-sectional view of a gel roll electrode assembly with the electrode plate of the first embodiment applied to the first electrode plate (anode plate) and the second electrode plate (cathode plate) cut along the Y-axis direction (winding axis direction).

[0083] Figure 12 It is a cross-sectional view of a gel roll electrode assembly with the electrode plate of the second embodiment applied to the first electrode plate (anode plate) and the second electrode plate (cathode plate) cut along the Y-axis direction (winding axis direction).

[0084] Figure 13 It is a cross-sectional view of a gel roll electrode assembly, which is cut along the Y-axis direction (winding axis direction) and any one of the electrode plates of the third to fifth embodiments (variations thereof) is applied to the first electrode plate (anode plate) and the second electrode plate (cathode plate).

[0085] Figure 14 This is a cross-sectional view of an electrode assembly of another embodiment of the present invention cut along the Y-axis direction (winding axis direction).

[0086] Figure 15 This is a cross-sectional view of an electrode assembly of another embodiment of the present invention cut along the Y-axis direction (winding axis direction).

[0087] Figure 16 This is a cross-sectional view of an electrode assembly of another embodiment of the present invention cut along the Y-axis direction (winding axis direction).

[0088] Figure 17 This is a cross-sectional view of a cylindrical battery cell according to an embodiment of the present invention, cut along the Y-axis direction.

[0089] Figure 18 This is a cross-sectional view of a cylindrical battery cell of another embodiment of the present invention cut along the Y-axis direction.

[0090] Figure 19 This is a cross-sectional view of a cylindrical battery cell of another embodiment of the present invention cut along the Y-axis direction.

[0091] Figure 20 This is a cross-sectional view of a cylindrical battery cell according to another embodiment of the present invention, cut along the Y-axis.

[0092] Figure 21 This is a cross-sectional view of a cylindrical battery cell of another embodiment of the present invention cut along the Y-axis.

[0093] Figure 22 This is a cross-sectional view of a cylindrical battery cell of another embodiment of the present invention cut along the Y-axis.

[0094] Figure 23 This is a cross-sectional view of a cylindrical battery cell of another embodiment of the present invention cut along the Y-axis.

[0095] Figure 24 This is a cross-sectional view of a cylindrical battery cell of another embodiment of the present invention cut along the Y-axis.

[0096] Figure 25 This is a cross-sectional view of a cylindrical battery cell of another embodiment of the present invention cut along the Y-axis.

[0097] Figure 26 This is a diagram that schematically illustrates the structure of a battery pack according to an embodiment of the present invention.

[0098] Figure 27 This is a schematic diagram of a car that includes a battery pack according to an embodiment of the present invention.

[0099] Figure 28 and Figure 29 The electrolyte immersion amount at various positions of the electrodes in the anode and cathode of the comparative example is shown.

[0100] Figure 30 and Figure 31 The amount of electrolyte impregnation at various locations of the electrodes in the anode and cathode of Example 1 is shown.

[0101] Figure 32 and Figure 33 The amount of electrolyte impregnation at various locations of the electrodes in the anode and cathode of Example 2 is shown.

[0102] Figure 34 The locations where the impregnated samples were removed in each comparative example, Example 1, and Example 2 are shown. Detailed Implementation

[0103] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Before proceeding, the terms and words used in this specification and claims should not be limited to their ordinary or dictionary meanings. Given the principle that inventors may appropriately define terms and concepts in order to best illustrate their invention, they should be interpreted as meanings and concepts consistent with the technical concept of the present invention.

[0104] Therefore, the embodiments described in this specification and the structures shown in the accompanying drawings are only the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. It should be understood that at the time of filing this application, there may be various equivalents and modifications that can replace these.

[0105] Furthermore, to aid in understanding the invention, the accompanying drawings are not shown to scale, but rather some of the constituent elements are depicted as enlarged versions. Additionally, in different embodiments, the same symbols are used for the same constituent elements.

[0106] For ease of explanation, the direction along the length of the winding axis of the electrode assembly wound in the form of a gel roll is referred to as the axial direction Y. The direction surrounding the winding axis is referred to as the circumferential direction or surrounding direction X. The direction closer to or farther from the winding axis is referred to as the radial direction or radial direction Z. Specifically, the direction closer to the winding axis is referred to as the sphere center direction, and the direction farther from the winding axis is referred to as the circle center direction.

[0107] First, the electrode assembly of an embodiment of the present invention will be described.

[0108] The electrode assembly includes a first electrode plate, a second electrode plate, and a separation membrane sandwiched between them. The first electrode plate, the second electrode plate, and the separation membrane are wound in one direction around an axis to obtain multiple windings. In addition, the first electrode plate and the second electrode plate each independently include a first side and a second side, which are arranged on opposite sides of each other in the axial direction.

[0109] In one embodiment of the present invention, the first electrode plate and the second electrode plate are rectangular sheets. Furthermore, the first electrode plate and the second electrode plate are sheets with an aspect ratio exceeding 1. In this case, each end edge in the width direction of each electrode plate corresponds to a first side and a second side.

[0110] Figure 4 This is a top view showing the structure of the electrode plate 40 according to the first embodiment of the present invention.

[0111] Reference Figure 4 The first side portion is formed along the lowest end of the electrode active material portion 42 in the winding axis direction Y, and the second side portion is formed along the highest end of the uncoated portion 43 in the winding axis direction Y.

[0112] The first electrode plate and the second electrode plate each independently include an electrode active material portion, i.e., a first portion, covered by electrode active material on at least one side or both sides. The first portion extends a predetermined length from the second side towards the first side. Figure 4 The figure shows the shape of the electrode plate before the electrode assembly is wound up. Referring to this figure, the active material portion of the electrode has a certain width along the entire length of the electrode plate from the second side to the uncoated portion in the axial direction.

[0113] The second part described above is the uncoated portion without electrode active material. This second part constitutes an electrode tab, extending in the second lateral direction from the first side to the electrode active material portion of the first part.

[0114] In one embodiment of the present invention, at least a portion of the uncoated portion is divided into multiple segments (not shown) by a cutting groove of a predetermined depth.

[0115] The aforementioned section has a first end corresponding to the first side portion. In one embodiment of the invention, all or at least a portion of the aforementioned section is bent radially relative to the axis at a certain position, i.e., a bending position, within the section below the first end, at which point either end of the separation membrane is located between the bending position and the boundary line of the first and second portions. According to a more specific embodiment of the invention, either end of the separation membrane is located between the bending position and a reference line or below the reference line.

[0116] On the other hand, in one specific embodiment, the aforementioned bending position is a predetermined position between the aforementioned first end and the baseline.

[0117] Thus, in the current collector of the present invention, the uncoated portion comprises multiple segments, and the separation membrane is configured such that the grooves between the segments are covered by the separation membrane and are not exposed. This configuration of the separation membrane will be described in more detail below.

[0118] In this invention, the heights of the first ends of the aforementioned cut pieces are different, the shapes of each cutting groove are different, and the heights of the grooves are also different. That is, the shape and size of the cut pieces themselves, and the shape and size of the cutting grooves themselves are different from each other.

[0119] On the other hand, the height of the aforementioned cut piece is defined as the axial distance C2, D2 from the valley of the cut groove on the cut piece to the first end of the cut piece. If, based on the cut piece, the valley heights of the cut grooves on both sides are different, then the height of the cut piece is defined as the axial distance from a position equivalent to the average height of the valleys of the cut grooves on both sides to the first end of the cut piece.

[0120] On the other hand, in this invention, the aforementioned baseline is a virtual straight line extending along the winding direction X, representing the height of the corresponding cut groove.

[0121] The first electrode plate and the second electrode plate each independently include a conductive thin film, i.e., a current collector, and an electrode active material layer disposed on one or both sides of the surface of the current collector. The active material layer forms a first portion on the electrode plate.

[0122] The aspect ratio of the aforementioned sheet-shaped first and second electrode plates exceeds 1. In this case, at least one of the uncoated portion of the first and second electrode plates is formed at the long side end in the winding direction. At least a portion of the uncoated portion itself serves as an electrode tab.

[0123] In one embodiment of the present invention, the uncoated portion includes a core-side uncoated portion adjacent to the core of the electrode assembly, an outer peripheral-side uncoated portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate uncoated portion sandwiched between the core-side uncoated portion and the outer peripheral-side uncoated portion.

[0124] Preferably, at least one of the uncoated portion on the core side and the uncoated portion on the outer periphery side is relatively higher than the uncoated portion in the middle.

[0125] On the other hand, for ease of explanation, in this specification, 'height' refers to the distance (length) from a predetermined position in the winding direction x to the first side portion in the axial direction. In this specification, when describing the height of the uncoated portion / groove, the relative value of the height measured at different positions in the winding direction is more meaningful than the absolute value of such a height; therefore, when measuring the height of the uncoated portion / groove, the definition of the reference line (zero point) constituting its height measurement is omitted. In one embodiment of the invention, the height of the uncoated portion is the relative distance at a specific position based on any perpendicular line relative to the winding axis direction. For example, the reference line (zero point) for the height measurement is the second side portion.

[0126] On the other hand, more specifically, in the height of the uncoated portion mentioned above, in the interval where no sliver is formed, it refers to the distance up to the first side portion, and in the interval where a sliver is formed, the first side portion refers to the position corresponding to the first end of the sliver. The portion that forms the cutting groove between the slivers is not considered when measuring the height of the uncoated portion in the interval where the sliver is formed.

[0127] In addition, the height of the aforementioned trough is measured based on the portion of the cut groove with the lowest height.

[0128] Reference Figure 4 The electrode plate 40 of the first embodiment includes a current collector 41 made of metal foil and an active material portion 42. The metal foil is aluminum or copper, appropriately selected according to the polarity of the electrode plate 40. An electrode active material layer is formed on at least one side of the current collector 41, and an uncoated portion 43 is disposed at the long side end of the current collector in the winding direction X. The uncoated portion 43 is the area where no active material is coated. An insulating coating 44 is formed at the boundary between the active material portion 42 and the uncoated portion 43. At least a portion of the insulating coating 44 is formed overlapping the boundary between the active material portion 42 and the uncoated portion 43. The insulating coating 44 includes a polymer resin, including inorganic materials such as Al2O3.

[0129] The aforementioned uncoated portion 43 includes a core-side uncoated portion B1 adjacent to the core side of the electrode assembly, an outer peripheral-side uncoated portion B3 adjacent to the outer peripheral side of the electrode assembly, and an intermediate uncoated portion B2 sandwiched between the core-side uncoated portion B1 and the outer peripheral-side uncoated portion B3.

[0130] The uncoated portion B1 on the core side, the uncoated portion B3 on the outer periphery side, and the uncoated portion B3 in the middle are defined as the uncoated portions of the areas adjacent to the core side, the areas adjacent to the outer periphery side, and the remaining areas, respectively, when each electrode plate 40 is wound into a gel roll type electrode assembly. The boundary of B1 / B2 is appropriately defined as the position where the height (or variation pattern) of the uncoated portion substantially changes as it moves from the core side of the electrode assembly towards the outer periphery side, or as a predetermined percentage of the radius of the electrode assembly (e.g., 5%, 10%, 15% of the radius, etc.). The boundary of B2 / B3 is defined as the position where the height (or variation pattern) of the uncoated portion substantially changes as it moves from the outer periphery side of the electrode assembly towards the core side, or as a predetermined percentage of the radius of the electrode assembly (e.g., 85%, 90%, 95% of the radius, etc.). When determining the boundaries of B1 / B2 and B2 / B3, the uncoated portion B2 in the middle is automatically determined. If only the boundaries of B1 / B2 are determined, the location of the boundary of B2 / B3 near the outer periphery of the electrode assembly can be appropriately selected. Conversely, if only the boundaries of B2 / B3 are determined, the boundary of B1 / B2 can be appropriately selected near the core side of the electrode assembly. In the first embodiment, the height of the uncoated portion 43 is not fixed and varies relatively in the winding direction X. That is, the height (length in the Y-axis direction) of the uncoated portion B3 on the outer periphery is relatively lower than that of the uncoated portion B1 on the core side and the uncoated portion B2 in the middle.

[0131] Figure 5 This is a top view showing the structure of the electrode plate 45 according to the second embodiment of the present invention.

[0132] Reference Figure 5 The electrode plate 45 of the second embodiment differs from that of the first embodiment only in the point where the height of the uncoated portion B3 on the outer periphery gradually decreases as it approaches the outer periphery; the rest of the structure is substantially the same.

[0133] In one variation, the uncoated portion B3 on the outer periphery can be deformed into a stepped shape with progressively decreasing height (refer to the dashed line). In one embodiment of the invention, at least a portion of the uncoated portion in the electrode plate of the second embodiment described above is divided into multiple segments (not shown) by a cut groove of a predetermined depth.

[0134] Figure 6 This is a top view showing the structure of the electrode plate 50 according to the third embodiment of the present invention.

[0135] Reference Figure 6 In the electrode plate 50 of the third embodiment, the heights of the uncoated portion B1 on the core side and the uncoated portion B3 on the outer periphery side are relatively lower than the height of the uncoated portion B2 in the middle. Furthermore, the heights of the uncoated portion B1 on the core side and the uncoated portion B3 on the outer periphery side are either the same or different from each other.

[0136] Preferably, the height of the uncoated portion B2 in the middle has a stepped shape that increases progressively from the core side to the outer periphery side.

[0137] Patterns 1 to 7 distinguish the intermediate uncoated portion B2 by the position where the height of the uncoated portion 43 changes. Preferably, the number of patterns and the height (length in the Y-axis direction) and width (length in the X-axis direction) of each pattern are adjusted in a way that maximizes stress dispersion during the bending process of the uncoated portion 43. Stress dispersion is used to prevent tearing of the uncoated portion 43.

[0138] The width d of the uncoated portion B1 on the core side B1 It is designed to meet the condition that the pattern of the uncoated middle part B2 is bent toward the core without obscuring the voids in the core of the electrode assembly.

[0139] In one embodiment of the present invention, at least a portion of the uncoated portion of the pattern 1 to pattern 7 in the electrode plate of the third embodiment is divided into multiple segments (not shown) by a cut groove of a predetermined depth.

[0140] In one example, the width d of the uncoated portion B1 on the core side B1 The length increases proportionally to the length from the baseline of Pattern 1 to the first side or the height of the section of Pattern 1.

[0141] In a specific example, when the electrode plate 60 is used to manufacture an electrode assembly for a cylindrical unit with a form factor of 46800, the width d of the uncoated portion B1 on the core side... B1 The diameter is set to 180 to 350 mm depending on the core diameter of the electrode assembly.

[0142] In one embodiment, the width of each pattern is designed in such a way that the same coils that make up the electrode assembly are designed.

[0143] In one variation, the height of the uncoated intermediate portion B2 has a stepped shape that increases as it moves from the core side toward the outer periphery side and then decreases.

[0144] In another variation, the uncoated portion B3 on the outer periphery is modified to have the same structure as in the second embodiment.

[0145] In another variation, the pattern structure applicable to the middle uncoated portion B2 is extended to the outer peripheral uncoated portion B3 (refer to the dashed line).

[0146] Figure 7a This is a top view showing the structure of the electrode plate 60 according to the fourth embodiment of the present invention. Figure 7a The diagram shows that a section is formed in the entire uncoated section in the middle.

[0147] Reference Figure 7a In the fourth embodiment, the heights of the uncoated portion B1 on the core side and the uncoated portion B3 on the outer periphery side of the electrode plate 60 are relatively lower than the uncoated portion B2 in the middle. Furthermore, the heights of the uncoated portion B1 on the core side and the uncoated portion B3 on the outer periphery side may be the same or different.

[0148] Preferably, at least a portion of the uncoated portion B2 includes a plurality of segments 61. The plurality of segments 61 increases progressively from the core side toward the outer periphery.

[0149] In this invention, all or at least a portion of the aforementioned cut piece is bent in the radial direction (winding center direction) of the electrode assembly or in the opposite direction. The bending of the cut piece occurs at a position spaced upwards from the groove (bottom of the cut groove) at a predetermined height. In this invention, the position where the inclination of the tangent in the portion where the cut piece is actually bent in the center direction by external force begins to be 45° or less is called the bending position. The inclination of the tangent refers to the angle between the tangent at the bending position and a plane perpendicular to the winding axis of the electrode assembly. Furthermore, the line including the aforementioned bending position and horizontal to the reference line is called the bend line.

[0150] On the other hand, in this invention, the heights corresponding to the grooves of the plurality of cut slots are either the same or different from each other.

[0151] When the heights mentioned above are the same, a virtual straight line extending along the winding direction X, corresponding to the height of the groove, is used as the baseline.

[0152] If most of the groove of the cut is located at a specific height, and only a portion of the groove's height differs from the specific height, the baseline is determined by the height corresponding to the specific height. For example, if more than 50% of the groove is located at the specific height, the baseline is determined by the height corresponding to that groove's height. Alternatively, the baseline is determined by the height of the groove of the cut that occupies the longest length in the winding direction. Assuming that two-thirds of the total length occupied by the groove of the cut in the winding direction has a first height, and the height of the remaining one-third of the total length occupied by the groove of the cut in the winding direction differs from the first height, the baseline is defined as the position corresponding to the first height.

[0153] If the heights of the grooves are not concentrated at a specific height (where the most concentrated grooves are less than 50%), the baseline is determined by the average height of the grooves. Assuming the groove height is x, it occupies 30% of the length in the winding direction; the groove height is y, it occupies 30% of the length in the winding direction; and the groove height is z, it occupies 40% of the length in the winding direction, then the baseline is x*0.3 + y*0.3 + z*0.4. The height of the grooves is the relative distance at a specific position relative to any perpendicular line relative to the winding axis. For example, the height of the grooves is based on the distance from the second side to the groove.

[0154] On the other hand, in one embodiment of the invention, the bending position is located about 2 mm to 3 mm above the valley and is arranged parallel to the baseline.

[0155] On the other hand, in one embodiment of the present invention, the reference line may be the same as or different from the line extending in the winding direction Y from the position where the uncoated portion has the minimum height. In a specific embodiment, the reference line is the same as the line extending in the winding direction from the position where the uncoated portion has the minimum height.

[0156] Cut-off piece 61 is grooved using a laser. Cut-off piece 61 is formed by a known metal foil cutting process such as ultrasonic cutting or punching.

[0157] In the fourth embodiment, to prevent damage to the active material portion 42 and / or the insulating coating 44 during bending of the uncoated portion 43, a gap of a predetermined interval is preferably provided between the grooves between the segments 61 and the active material portion 42. This is because stress concentrates near the lower end of the cutting line when bending the uncoated portion 43. The gap is preferably 0.2 to 4 mm. When the gap is adjusted to this range, damage to the active material portion 42 and / or the insulating coating 44 near the lower end of the cutting line can be prevented due to stress generated during bending of the uncoated portion 43. In addition, 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, when the electrode plate 40 is wound into an electrode assembly, at least a portion of the insulating coating 44 is exposed to the outside of the separation membrane. In this case, the insulating coating 44 supports the grooves when bending the segments 61.

[0158] The gap between the grooves of the aforementioned cut piece and the aforementioned active material layer is preferably 1.0 mm or more. This is more effective when the electrode is a cathode.

[0159] The gap between the aforementioned truncated groove and the aforementioned active material layer is more preferably 2.0 mm or more. This is more effective when the electrode is an anode.

[0160] A gap smaller than the above range cannot fully exert the above-mentioned damage prevention effect, while a gap larger than the above range can only reduce the electrode capacity without increasing the damage prevention effect.

[0161] The boundary between the uncoated area where the active material layer is not applied and the area where the active material layer is applied is covered by an insulating layer, and at this time, there is also a predetermined gap between the groove of the above-mentioned cut piece and the insulating layer.

[0162] Such gaps range from 0.2mm to 1.5mm.

[0163] Gap smaller than the above range cannot fully exert the above-mentioned damage prevention effect, while gap larger than the above range will only reduce the bending support effect of the insulating coating without increasing the damage prevention effect.

[0164] Multiple segments 61 are arranged into multiple segments groups as they move from the core side to the outer periphery. Segments belonging to the same segment group have substantially the same width, height, and spacing between them.

[0165] exist Figure 7a and Figure 9a In this embodiment, an electrode assembly is formed by including the active material portion 42 of the electrode plate 60 of the fourth embodiment and / or the separation membrane SP opposite to the insulating coating 44.

[0166] Reference Figure 7b , Figure 7c , Figure 8 , Figure 9b and Figure 9c The position of the end of the electrode assembly of the present invention having a separation membrane on the uncoated portion side of the electrode plate will be described in more detail.

[0167] Referring to the above figures, and taking one embodiment of the present invention as an example, the uncoated portion includes multiple segments, and the depth of the grooves between the multiple segments is the same. The line extending from the position corresponding to the depth of the groove is called a reference line.

[0168] At this time, the aforementioned baseline corresponds to the line that connects the minimum height of the uncoated portion on the core side, the uncoated portion on the outer periphery side, and the uncoated portion in the middle to the two ends of the uncoated portion.

[0169] In this invention, the end SL in the width direction of the separation membrane is located between the bending position and the reference line DL, or is disposed from the reference line toward the inner side of the electrode assembly. Here, the outer direction of the electrode assembly refers to the direction from the active material layer of the electrode plate toward the uncoated portion, i.e., toward the first side, and the inner direction refers to the opposite direction of the outer direction, i.e., toward the second side.

[0170] Furthermore, in one embodiment of the present invention, the electrode assembly includes a surface region formed at the upper or lower end of the take-up axis direction by the continuous overlapping of adjacent winding loops in the bent segments in the radial direction or opposite direction. In this case, assuming the shortest distance between the maximum height (highest point) in the take-up axis direction of the surface region and the reference line is the height HS of the surface region, the end of the separation membrane in the width direction is located outside the electrode assembly or disposed inside the electrode assembly within 90% of the height HS of the surface region, based on the reference line.

[0171] According to one embodiment of the invention, the end of the separation membrane in the width direction is positioned close to the aforementioned reference line, so that the electrolyte flows into the electrode assembly along the valley (empty space), thus facilitating impregnation. Specifically, as the electrolyte enters the electrode assembly, it moves towards the slit groove between the segments, where it re-impregnates the end of the separation membrane positioned close to the valley, i.e., the aforementioned reference line, and finally impregnates the active material layer of the electrode. As a result, the uniformity of electrolyte impregnation within the electrode assembly is increased.

[0172] The further the end of the separation membrane in the width direction moves away from the outside of the gel roll, i.e. the outside of the electrode assembly, the more adverse the welding characteristics become. The further the end of the separation membrane in the width direction moves into the inside of the gel roll, i.e. the inside of the electrode assembly, the greater the risk of a short circuit between the anode and cathode, thus becoming a problem.

[0173] Therefore, in this invention, the end of the separation membrane in the width direction is located outside the electrode assembly with reference to the reference line, or the end of the separation membrane in the width direction is located inside the electrode assembly with reference to the reference line, and more preferably, it is configured to be 90% or less relative to the height HS of the surface area.

[0174] On the other hand, in one embodiment of the present invention, when the segment with the smallest height among the multiple bent segments is referred to as the smallest bent segment, the end of the separation membrane in the width direction is located in the outer direction (1 side direction) of the electrode assembly, based on the reference line, within 50%, 40%, 30%, 20%, or 10% of the height Ha of the smallest bent segment. Preferably, it is located in the outer direction of the electrode assembly within 30%. In this case, the separation membrane is configured such that the grooves of the cutting grooves between the segments are covered by the separation membrane and are not exposed.

[0175] If the separation membrane is positioned beyond the aforementioned range and closer to the first end of the cut piece, it may be damaged by heat during subsequent welding of the cut piece. According to another embodiment, the end of the separation membrane in the width direction is positioned within 30%, 20%, or 10% of the minimum bending cut piece height Ha, relative to the aforementioned reference line, in the inner direction (2-side direction) of the electrode assembly. Thus, when positioned below the reference line, all or at least a portion of the aforementioned grooves are exposed and not covered by the separation membrane.

[0176] According to the above Figure 7b , Figure 7c , Figure 9b Or, in group 9c, the cut piece is the minimum bending cut piece, with one end of the separation membrane in the width direction located on the outer side (1 side direction) of the electrode assembly within 30% of the height Ha of the minimum bending cut piece, based on the reference line; or with the end of the separation membrane in the width direction located on the inner side (2 side direction) of the electrode assembly within 50% or 30% of the height Ha of the minimum bending cut piece, based on the reference line. More specifically, the cut piece of group 1 is the minimum bending cut piece, with one end of the separation membrane in the width direction located on the outer side (1 side direction) of the electrode assembly within 30% of the height Ha of the minimum bending cut piece, based on the reference line. (See reference...) Figure 7b or Figure 9b If one end of the separation membrane is positioned above the baseline, then that end lies between Hb. Here, the maximum length of Hb is less than 50% of the minimum bending section height (length). Alternatively, when one end of the separation membrane is below DL, the maximum length of Hb is 30% of the minimum bending section height.

[0177] That is, in this invention, the segment constituting the reference for configuring the separation membrane refers to the segment with the smallest height among the segments forming a bend (bend), which is called the smallest bend segment.

[0178] In one specific embodiment of the present invention, the minimum bending section is 2 mm or more, and in this case, the height of the minimum bending section is higher than the height of the bending position. If the height of the section is less than 2 mm, interference between the separation membrane and the section may prevent the section from being bent smoothly. Therefore, the minimum bending section is determined to be one with a height of 2 mm or more.

[0179] According to one embodiment of the present invention, in the aforementioned minimum bending section, with the bending line as a reference, the height A from the reference line to the bending line is greater than or equal to the length from the bending line to the section height B. Alternatively, in the aforementioned minimum bending section, the height A from the reference line to the bending line as a reference is less than or equal to the length from the bending line to the section height B.

[0180] In another embodiment of the invention, the electrode assembly further includes a segment (segment A) smaller than the minimum bending segment height. In this case, segment A is not bent. In a specific embodiment, segment A is positioned closer to the core than the other segments among a plurality of segments.

[0181] In one embodiment of the present invention, the electrode assembly does not include a segment smaller than the minimum bending segment height, which is the minimum segment.

[0182] According to one embodiment of the present invention, the end of the separation membrane in the width direction is located within 3 mm or 1.5 mm of the reference line in the outer direction of the electrode assembly, or the end of the separation membrane in the width direction is located within 3 mm or 1.5 mm of the reference line in the inner direction of the electrode assembly.

[0183] Figure 8 This is a diagram illustrating the width, height, and spacing between segments 61 according to an embodiment of the present invention.

[0184] Reference Figure 8 The width C1, height C2, and spacing C3 of the section 61 are designed to prevent the uncoated portion 43 from tearing during bending and to improve welding strength. This is achieved by increasing the number of overlapping layers of the uncoated portion 43 and preventing abnormal deformation. Abnormal deformation refers to the portion C4, corresponding to the baseline DL, deforming irregularly instead of maintaining a straight line.

[0185] According to one embodiment of the present invention, it is preferable to adjust the width C1 of the cut piece 61 within the range of 1 to 6 mm. When C1 is less than 1 mm, when the cut piece 61 is bent towards the core side, areas or gaps occur where the overlap is insufficient to ensure sufficient welding strength. Conversely, when C1 exceeds 6 mm, due to the curvature of the wound electrode, the uncoated portion 43 near the reference line DL may be torn by stress when the cut piece 61 is bent. Additionally, the height C2 of the cut piece 61 is adjusted within the range of 2 mm to 10 mm. When the height C2 of the cut piece 61 is less than 2 mm, areas or gaps occur where the overlap is insufficient to ensure sufficient welding strength when the cut piece 61 cannot be bent smoothly or when the cut piece 61 is bent towards the core side. Conversely, when C2 exceeds 10 mm, it is difficult to maintain the flatness of the uncoated portion uniformly in the winding direction X to manufacture the electrode plate. That is, the height of the uncoated portion increases, resulting in wrinkling.

[0186] Additionally, the spacing C3 of the cut pieces 61 can be adjusted within the range of 0.05 to 1 mm or 0.5 mm to 1 mm. When C3 is less than 0.05 mm, when the cut piece 61 is bent, stress may cause the uncoated portion 43 near the baseline DL (near the bottom of the cut groove between two adjacent cut pieces) to tear. Conversely, when the spacing C3 exceeds 1 mm, when the cut pieces 61 are bent, areas or gaps occur where the cut pieces 61 do not overlap to a degree sufficient to ensure weld strength.

[0187] In one embodiment of the invention, the corners of the two segments are connected in a straight line. That is, the bottom portion of the cutting groove has a flat, straight line shape extending in the winding direction X. A chamfered reinforcement is added to the corner portion.

[0188] The radius r of the aforementioned chamfered reinforcement is 0.02 mm or more. When this radius is 0.02 mm or more, a reliable stress dispersion effect can be achieved. The radius of the aforementioned chamfered reinforcement is 0.1 mm or less. When this radius exceeds 0.1 mm, the stress dispersion effect no longer increases, the space near the bottom of the cut groove decreases, and the electrolyte impregnation decreases.

[0189] Re-reference Figure 7a The width d of the uncoated portion B1 on the core side B1 It is designed to be suitable for situations where the core cavity of the electrode assembly is not obstructed when the uncoated section 61 of the middle part B2 is bent toward the core side.

[0190] In one example, the width d of the uncoated portion B1 on the core side B1 It increases in proportion to the height C2 of the section 61 of group 1.

[0191] In a specific example, when the electrode plate 60 is used to manufacture an electrode assembly for a cylindrical unit with a form factor of 46800, the width d of the uncoated portion B1 on the core side... B1 The diameter is set to 180 to 350 mm depending on the core diameter of the electrode assembly.

[0192] In one embodiment, the width of each sliver group is designed in such a way that the same coils that form the electrode assembly are arranged.

[0193] In one variation, the width and / or height and / or spacing of the segments 61 belonging to the same segment group gradually and / or periodically and / or irregularly increase or decrease within the group.

[0194] Groups 1 to 7 are merely examples of cut piece groups. The number of groups and the number of cut pieces 61 included in each group are adjusted in a way that the cut pieces 61 are overlapped in multiple layers to maximize stress dispersion and ensure sufficient weld strength during the bending process of the uncoated portion 43.

[0195] In other variations, the height of the uncoated outer peripheral portion B3 gradually or gradually decreases, similar to the first and second embodiments. Furthermore, the slicing structure of the intermediate uncoated portion B2 can be extended up to the uncoated outer peripheral portion B3 (refer to the dashed line). In this case, the uncoated outer peripheral portion B3 also includes multiple segments, similar to the intermediate uncoated portion B2. In this case, the width and / or height and / or spacing of the segments in the uncoated outer peripheral portion B3 are greater than those in the intermediate uncoated portion B2.

[0196] In a specific example, when the electrode plate 60 is used to manufacture an electrode assembly of a cylindrical unit with a shape factor of 46800, it is formed into eight groups of segments. In this case, segments of groups 1 to 7 are formed in the middle uncoated portion B2, and segment of group 8 is formed in the outer peripheral uncoated portion B3 as in the modified example described above.

[0197] In a specific example, the width d of the uncoated portion B1 on the core side B1 The width of group 1 is 180–350 mm. The width of group 1 is 35–40% of the width of the uncoated core portion B1. The width of group 2 is 130–150% of the width of group 1. The width of group 3 is 120–135% of the width of group 2. The width of group 4 is 85–90% of the width of group 3. The width of group 5 is 120–130% of the width of group 4. The width of group 6 is 100–120% of the width of group 5. The width of group 7 is 90–120% of the width of group 6. The width of group 8 is 115–130% of the width of group 7.

[0198] The reason why the widths of groups 1 to 8 do not show a definite increasing or decreasing pattern is that the width of the segments gradually increases from group 1 to group 8, but the number of segments included in the group is limited to a predetermined quantity. Therefore, the number of segments in a particular segment group may decrease. Thus, the width of the group shows an irregular variation pattern as it moves from the core side towards the outer periphery side, as illustrated above.

[0199] That is, when the widths of three consecutive adjacent cut pieces in the radial direction of the electrode assembly are respectively set as W1, W2 and W3 in the winding direction, W3 / W2 includes a combination of smaller cut pieces compared to W2 / W1.

[0200] In the specific example above, groups 4 to 6 are equivalent to this. The width ratio of group 5 to group 4 is 120% to 130%, and the width ratio of group 6 to group 5 is 100% to 120%, which is less than 120% to 130%.

[0201] Figure 9aThis is a top view showing the structure of the electrode plate 70 according to the fifth embodiment of the present invention.

[0202] Reference Figure 9a Compared with the fourth embodiment, the electrode plate 70 of the fifth embodiment is substantially the same as the fourth embodiment (or its variant) except that the shape of the section 61' changes from a quadrilateral to a trapezoid.

[0203] Figure 10 This defines the width, height, and spacing of the trapezoidal segment 61'.

[0204] Reference Figure 10 Regarding the width D1, height D2, and spacing D3 of the section 61', it is designed to prevent the uncoated portion D4 around the baseline DL from being torn during the bending process of the uncoated portion 43, and to ensure sufficient welding strength, while increasing the number of overlapping layers of the uncoated portion 43 and preventing abnormal deformation of the uncoated portion 43.

[0205] Preferably, the width D1 of the cut piece 61' can be adjusted within the range of 1 mm to 6 mm. When D1 is less than 1 mm, when the cut piece 61' is bent towards the core side, an area where the cut piece 61' does not overlap to a degree sufficient to ensure welding strength or an empty space (gap) occurs. Conversely, when D1 exceeds 6 mm, due to the curvature of the wound electrode, the uncoated portion 43 around the reference line DL may be torn by stress when bending the cut piece 61'. Additionally, the height of the cut piece 61' can be adjusted within the range of 2 mm to 10 mm. When D2 is less than 2 mm, the cut piece 61' cannot be bent smoothly, or when the cut piece 61' is bent towards the core side, an area where the cut piece 61' does not overlap to a degree sufficient to ensure welding strength or an empty space (gap) occurs. Conversely, when D2 exceeds 10 mm, it is difficult to maintain the flatness of the uncoated portion 63 uniformly in the winding direction when manufacturing the electrode plate. Additionally, the spacing D3 of the segments 61' is adjusted within the range of 0.05 mm to 1 mm. When D3 is less than 0.05 mm, stress may cause the uncoated portion D4 around the baseline DL to tear when bending the segment 66'. Conversely, when D3 exceeds 1 mm, areas or gaps occur where the segments 61' do not overlap to a sufficient degree to ensure weld strength when bending the segments 61'.

[0206] When the aforementioned cut pieces are trapezoidal, the spacing D3 is defined as the distance between the corners of two adjacent cut pieces 61'. The corners of two adjacent cut pieces are connected by a straight line. That is, the bottom part of the cutting groove has a flat straight line shape extending in the winding direction X.

[0207] The aforementioned corner areas also feature chamfered reinforcement. This helps to resolve stress concentration issues that occur at the corners.

[0208] The radius r of the aforementioned chamfered reinforcement is 0.02 mm or more. When this radius is greater than or equal to this value, a reliable stress dispersion effect can be achieved.

[0209] The radius of the aforementioned chamfered reinforcement is 0.1 mm or less. When the radius exceeds 0.1 mm, the stress dispersion effect no longer increases, and the space near the bottom of the cut groove decreases, resulting in a decrease in the impregnation properties of the electrolyte.

[0210] The aforementioned spacing C3 and D3 are determined in relation to the widths C1 and D1 measured in the winding direction of adjacent segments 61 and 61'. As the width of the segments in the winding direction increases, it is preferable that the spacing between them also increases. This results in a uniform distribution of electrolyte impregnation according to the winding direction of the electrode assembly.

[0211] The width of the aforementioned cut sheet in the winding direction is set such that it gradually increases from the core side of the electrode assembly towards the outer periphery. The width of the aforementioned cut sheet in the winding direction gradually increases or increases in stages from the core side of the electrode assembly towards the outer periphery. The widths C1 and D1 of the aforementioned cut sheet in the winding direction range from 1 to 6 mm, decreasing closer to the core side and increasing closer to the outer periphery side.

[0212] Therefore, the aforementioned spacing C3 and D3 also exist in the range of 0.5 to 1 mm, gradually increasing or increasing in stages from the core side of the electrode assembly towards the outer periphery.

[0213] In the fifth embodiment, as the plurality of segments 61' move closer to the outer periphery from the core side, the lower interior angle θ of the trapezoid increases. As the radius of the electrode assembly 70 increases, the radius of curvature also increases. When the lower interior angle θ of the segments 61' increases along with the radius of the electrode assembly, stress generated in the radial and circumferential directions can be alleviated when bending the segments 61'. Furthermore, as the lower interior angle θ increases, the area and number of overlapping layers with the inner segments 61' also increase when bending the segments 61', thereby ensuring uniform welding strength in both the radial and circumferential directions and forming a flat bending surface.

[0214] In one example, when the electrode plate 70 is used to manufacture an electrode assembly for a cylindrical unit with a form factor of 46800, the inner angle of the cut 61' increases in stages from 60 degrees to 85 degrees as the radius of the electrode assembly 70 increases from 4 mm to 22 mm.

[0215] In a variation, the height of the uncoated outer peripheral portion B3 gradually or gradually decreases, similar to the first and second embodiments. Furthermore, the slicing structure of the intermediate uncoated portion B2 can be extended to the uncoated outer peripheral portion B3 (refer to the dashed line). In this case, the uncoated outer peripheral portion B3 also includes multiple segments, similar to the intermediate uncoated portion B2. In this case, the width and / or height and / or spacing of the segments in the uncoated outer peripheral portion B3 are greater than those in the intermediate uncoated portion B2.

[0216] In the fourth and fifth embodiments, when the uncoated portion B2 includes multiple segments 60 and 60', the shape of each segment 60 and 60' can be changed to a triangle, a semicircle, a semi-ellipse, a parallelogram, etc.

[0217] Furthermore, the shapes of the segments 60 and 60' can be changed to different depending on the uncoated area B2 in the middle. In one example, a chamfered shape (e.g., semicircle, semi-ellipse, etc.) that facilitates stress dispersion is suitable for areas with concentrated stress, while a polygonal shape with a large area (e.g., quadrilateral, trapezoid, parallelogram, etc.) is suitable for areas with relatively lower stress.

[0218] In the fourth and fifth embodiments, the slitting structure of the intermediate uncoated portion B2 can also be applied to the core-side uncoated portion B1. However, when the slitting structure is applied to the core-side uncoated portion B1, when the segments 60 and 60' of the intermediate uncoated portion B2 are bent according to the radius of curvature of the core, a reverse forming phenomenon can occur, where the ends of the core-side uncoated portion B1 twist outwards. Therefore, the slitting structure is not applicable to the core-side uncoated portion B1. Even if the slitting structure is applied, considering the radius of curvature of the core, it is preferable to adjust the width and / or height and / or spacing of the segments 60 and 60' to a level that prevents reverse forming.

[0219] The height of the cut piece that can undergo such reverse forming is approximately less than 3 mm. Furthermore, when the cut piece height is less than 2 mm, interference occurs between the cut piece and the separation membrane, making bending difficult. Moreover, when the cut piece height is less than 4 mm, the welding process cannot be performed smoothly. Therefore, to facilitate bending, the minimum height H of the cut piece is... min The setting is 2mm or more, or 3mm or more, or 4mm or more, or 5mm or more. Therefore, the minimum bending section height is 2mm or more, or 3mm or more, or 4mm or more, or 5mm or more.

[0220] Therefore, taking the baseline DL as a reference, in the uncoated section, there is a minimum bendable height (H) minWhen the end SL in the width direction of the separation membrane exists within ±30% of the height Ha of the minimum bending section (reference line reference) of the section with a height of 2mm, 3mm, 4mm, or 5mm or higher, the impregnation can be greatly improved. That is, when determining the minimum section for the position of the end SL in the width direction of the separation membrane, sections that will undergo reverse forming or sections that do not bend can be excluded.

[0221] From another perspective, taking the baseline DL as a reference, the minimum bending section height Ha and the aforementioned minimum bendable height H in the uncoated portion are considered. min The maximum height of the medium-sized {Ha, H} min) When the end SL of the separation membrane is present in the width direction within a range of ±30%, the impregnation property can be greatly improved.

[0222] From another perspective, taking the baseline DL as a reference, within the aforementioned minimum bendable height H... min When the end SL of the separation membrane in the width direction is present within a range of ±30%, the impregnation of the electrolyte can be greatly improved. This is within the range of ±1.5 mm, ±1.2 mm, ±0.9 mm, or ±0.6 mm of the reference line (DL).

[0223] Alternatively, the position of the end of the separation membrane in the width direction is in the range of DL±0.3Ha and exists in the range of DL±1.5mm, the position of the end of the separation membrane in the width direction is in the range of DL±0.3Ha and exists in the range of DL±1.2mm, the position of the end of the separation membrane in the width direction is in the range of DL±0.3Ha and exists in the range of DL±0.9mm, or the position of the end of the separation membrane in the width direction is in the range of DL±0.3Ha and exists in the range of DL±0.6mm.

[0224] The electrode plate structure of the above-described embodiments (modified examples) is applicable to at least one of a first electrode plate and a second electrode plate with different polarities included in a gel roll-type electrode assembly. Furthermore, if the electrode structure of the embodiments (modified examples) is applied to either the first electrode plate or the second electrode plate, a conventional electrode plate structure is applied to the other. Additionally, the structures of the electrode plates applied to the first electrode plate and the second electrode plate are different from each other.

[0225] As an example, when the first electrode plate and the second cathode plate are respectively the anode plate and the cathode plate, in one of the embodiments (modified examples) applicable to the first electrode plate, the structure of a conventional electrode plate is applied to the second electrode plate (see reference). Figure 1 ).

[0226] As another example, when the first electrode plate and the second cathode plate are respectively the anode plate and the cathode plate, one of the embodiments (modified examples) is selectively applied to the first electrode plate, and one of the embodiments (modified examples) is selectively applied to the second electrode plate.

[0227] In this invention, any active material known in the art can be used for the anodic active material coated on the anode plate and the cathode active material coated on the cathode plate.

[0228] The aforementioned anolyte active material is a layered compound such as lithium cobalt oxide (LiCoO2) or lithium nickel oxide (LiNiO2), or a compound containing one or more transfer metals, or a compound with the chemical formula Li. 1+x Mn 2-x O4 (here, x is 0 to 0.33), lithium manganese oxides such as LiMnO3, LiMn2O3, and LiMnO2 (LiMnO2), lithium copper oxides such as Li2CuO2, vanadium oxides such as LiV3O8, LiFe3O4, V2O5, and Cu2V2O7, and 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) represents lithium-type nickel oxide, with the chemical formula LiMn. 2-x M x The lithium intercalation material is a lithium manganese composite oxide represented by O2 (here, M = Co, Ni, Fe, Cr, Zn or Ta, x = 0.01 to 0.1) or Li2Mn3MO8 (here, M = Fe, Co, Ni, Cu or Zn), LiMn2O4 in which a portion of the lithium is replaced by an alkaline earth metal ion, disulfide compounds, Fe2(MoO4)3 or composite oxides formed by combinations thereof, and has the types mentioned above, but is not limited to them.

[0229] The aforementioned anode current collector has a thickness of, for example, 3 to 500 μm. There are no particular limitations on such anode current collectors, as long as they do not cause chemical changes in the battery and possess conductivity; for example, stainless steel, aluminum, nickel, titanium, plastic carbon, or aluminum can be used, or stainless steel can be surface-treated with carbon, nickel, titanium, silver, etc. The electrode current collector has fine irregularities formed on its surface, thereby improving the adhesion of the anode active material, and can be formed into various forms such as thin films, sheets, foils, meshes, porous bodies, foams, and nonwoven fabrics.

[0230] The above-mentioned anode active material particles are also mixed with a conductive material. Such a conductive material is added, for example, in an amount of 1 to 50% by weight based on the total weight of the mixture including the anode active material. Regarding such a conductive material, as long as it does not cause chemical changes in the battery and has high conductivity, it is not particularly limited. For example, natural graphite, artificial graphite and other graphites, carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black and other carbon blacks, carbon fibers, metal fibers and other conductive fibers; metal powders such as carbon fluoride, aluminum, nickel powder; conductive whiskers such as zinc oxide, potassium titanate; conductive oxides such as titanium oxide, conductive materials such as polyphenyl derivatives, etc. can be used.

[0231] In addition, the cathode is prepared by coating cathode active material particles on a cathode current collector and drying. As needed, it may also include components such as the above-mentioned conductive material, binder, solvent, etc.

[0232] The above-mentioned cathode current collector has a thickness of, for example, 3 to 500 μm. Regarding such a cathode current collector, as long as it does not cause chemical changes in the battery and has conductivity, it is not particularly limited. For example, copper, stainless steel, aluminum, nickel, titanium, plastic carbon, products obtained by surface treatment of copper or stainless steel with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. can be used. In addition, similar to the anode current collector, fine concavities and convexities are formed on the surface to strengthen the bonding force of the cathode active material, and it can be used in various forms such as films, sheets, foils, meshes, porous bodies, foams, non-woven fabric bodies, etc.

[0233] As the above-mentioned cathode active material, for example, non-graphitizable carbon, carbon such as graphite-like carbon, Li x Fe2O3(0≤x≤1), Li x WO2(0≤x≤1), Sn x Me 1-x Me' y O z (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, elements of Group 1, Group 2, Group 3 of the periodic table, halogens; 0 < x ≤ 1; 1 ≤ y ≤ 3; 1 ≤ z ≤ 8) metal composite oxides, lithium metal, lithium alloy, silicon-based alloy, tin-based alloy, SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, Bi2O5 and other oxides, conductive polymers such as polyynes, Li-Co-Ni-based materials, etc.

[0234] The binder polymer that can be used in the above-mentioned electrodes is a component that facilitates the bonding of electrode active material particles and conductive materials, as well as the bonding of electrode current collectors. For example, 1 to 50% by weight can be added based on the total weight of the mixture including the electrode active material. Examples of such adhesive polymers include those selected from polyvinylidene fluoride-co-hexafluoropropylene (PVdF), polyvinylidene fluoride-co-trichloroethylene, polymethyl methacrylate, polybutyl acrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, polyvinyl-co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, and cyanoethyl pullulan. The adhesive polymer is any one of the following groups: pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, and carboxyl methyl cellulose, or a mixture of two or more thereof, but not limited thereto.

[0235] Examples of solvents used in the above-mentioned electrode fabrication include, but are not limited to, acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone, NMP, cyclohexane, water, or mixtures thereof. Such solvents can provide an appropriate level of viscosity to form a slurry coating layer of the desired level relative to the electrode current collector surface.

[0236] The cathode comprises a current collector and an active material layer of the cathode located on at least one side of the current collector, comprising a cathode active material, an adhesive polymer, and a conductive material. The active material layer of the cathode is composed of a lower region in contact with the surface of the current collector and an upper region in contact with the surface of the lower region and extending to the surface of the active material layer of the cathode. The lower region and the upper region are each independently provided as cathode active materials, comprising at least one of graphite and silicon compounds.

[0237] The lower region mentioned above includes natural graphite as the cathode active material, and the upper region mentioned above includes artificial graphite as the cathode active material.

[0238] The aforementioned lower and upper regions are independently used as cathode active materials and also include silicon-based compounds.

[0239] The aforementioned silicon compounds include one or more of SiOx (0≤x≤2) and SiC.

[0240] According to one embodiment of the present invention, the cathode is formed by coating a lower layer slurry, which is a cathode active material for the lower layer, onto a current collector and drying it to form a lower layer region, and then coating an upper layer slurry, which is a cathode active material for the upper layer, onto the lower layer region and drying it to form an upper layer region.

[0241] Furthermore, according to one embodiment of the present invention, the cathode described above is obtained by a method comprising the following steps:

[0242] Prepare a lower layer slurry including a lower layer cathode active material and an upper layer slurry including an upper layer cathode active material;

[0243] The lower layer paste is applied to one side of the cathode current collector, and the upper layer paste is applied on top of the lower layer paste simultaneously or at a predetermined time interval; and

[0244] The lower and upper coating slurries are dried simultaneously to form an active material layer.

[0245] Thus, when manufactured using the latter method, a mixing region (intermixing section) exists in the cathode at the junction of the lower and upper regions, where these different types of active materials are mixed together. This is because when the lower slurry, which is the active material of the lower cathode, and the upper slurry, which is the active material of the upper cathode, are simultaneously or with a very short time difference coated onto the current collector and then dried simultaneously to form an active material layer, a predetermined mixing zone occurs at the cross-section where the lower and upper slurries are connected before drying, and then, as drying continues, such a mixing zone is formed in the form of a mixing region layer.

[0246] In one embodiment of the present invention, the weight ratio (or the ratio of the amount of loading per unit area) of the upper region to the lower region in the active material layer of the cathode is 20:80 to 50:50, specifically 25:75 to 50:50.

[0247] The thicknesses of the lower and upper regions of the active material layer of the cathode of the present invention may not be completely consistent with the thicknesses of the lower and upper coating slurries described above. However, after drying or selective calendering processes, the final thickness ratio of the lower and upper regions of the active material layer of the cathode of the present invention is consistent with the thickness ratio of the lower and upper coating slurries described above.

[0248] The first slurry is applied, and simultaneously or at a predetermined time difference, the second slurry is applied onto the first slurry. According to one embodiment of the invention, the predetermined time difference is less than 0.6 seconds, or 0.02 to 0.6 seconds, or 0.02 to 0.06 seconds, or 0.02 to 0.03 seconds. Since the time difference between applying the first and second slurries is caused by the coating equipment, it is preferable to apply the first and second slurries simultaneously. A device such as a double-slot die can be used in the method of applying the second slurry onto the first slurry.

[0249] In the step of forming the above-mentioned active material layer, a step of calendering the active material layer is included after the drying step. At this time, calendering is performed by a method commonly used in the art, such as a roll pressing, for example, at a pressure of 1 to 20 MPa and a temperature of 15 to 30°C.

[0250] In the step of simultaneously drying the lower and upper coating slurries to form an active material layer, the process is carried out using an apparatus that combines hot air drying and infrared drying devices, and by methods commonly used in the art.

[0251] In the aforementioned lower layer slurry solid powder, the weight percentage of the first binder polymer is the same as or greater than the weight percentage of the second binder polymer in the aforementioned upper layer slurry solid powder. According to one embodiment of the invention, the weight percentage of the first binder polymer in the aforementioned lower layer slurry solid powder is 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 aforementioned upper layer slurry solid powder.

[0252] At this time, the weight percentage of the first adhesive in the lower layer slurry and the weight percentage of the upper layer slurry are as follows: When the weight percentage of the second adhesive in the middle meets such a range, the adhesive in the lower region is not too little and the electrode layer will not detach, and the adhesive in the upper region is not too much and the resistance of the upper part of the electrode is reduced, which is beneficial to the rapid charging performance.

[0253] In the solid powder of the lower layer slurry, the weight percentage of the first binder polymer is 2 to 30% by weight, or 5 to 20% by weight, or 5 to 20% by weight; and in the solid powder of the upper layer slurry, the weight percentage of the second binder polymer is 0.5 to 20% by weight, or 1 to 15% by weight, or 1 to 10% by weight, or 2 to 5% by weight.

[0254] In all the solid powders of the aforementioned lower layer slurry and the aforementioned upper layer slurry, the total ratio (by weight) of the first binder polymer and the second binder polymer is 2 to 20% by weight or 5 to 15% by weight.

[0255] The separation membrane comprises: a porous polymer substrate; and a porous coating located on at least one or both sides of the porous polymer substrate, and comprising inorganic particles and adhesive polymers.

[0256] The aforementioned porous polymer substrate is a polyolefin porous substrate.

[0257] The aforementioned polyolefin porous substrate is in the form of a film or a non-woven web. This porous structure facilitates the smooth movement of the electrolyte between the anode and cathode, and also increases the electrolyte impregnation of the substrate itself, thereby ensuring excellent ionic conductivity, preventing an increase in the internal resistance of the electrochemical element, and thus preventing a decline in the performance of the electrochemical element.

[0258] Regarding the polyolefin porous substrate used in this invention, any planar porous substrate commonly used in electrochemical components can be used, and various materials or forms can be selected according to the desired situation.

[0259] The polyolefin porous substrate can be formed from high-density polyethylene, low-density polyethylene, linear low-density polyethylene, ultra-high molecular weight polyethylene, polypropylene, or a mixture of two or more of them. Films or non-woven webs, but not limited to these.

[0260] The aforementioned polyolefin porous substrate has a thickness of 8 to 30 μm, but this is only an example. Considering the mechanical properties or the efficient charge and discharge characteristics of the battery, a thickness outside the above range can also be selected.

[0261] The nonwoven sheet of the present invention can be formed from polyethylene (PE), polypropylene (PP), or a mixture of two or more thereof. For example, the nonwoven sheet can be produced by fiber radiation. For example, it can be produced by blending and radiation by using a melt-blowing method to manufacture the fibers of the above-mentioned materials into a fiber radiation pattern above their melting point.

[0262] The aforementioned nonwoven sheet has an elongation of 200% to 400%, more preferably 300% to 400%. When the elongation is less than 200%, the probability of contact between electrodes when penetration is not achieved increases. When the elongation is greater than 400%, the membrane extends even in the peripheral areas where penetration is not achieved, resulting in a thinner separation membrane and a decrease in barrier properties.

[0263] The aforementioned nonwoven fabric sheet has multiple pores with an average diameter of 0.1 to 10 μm. When the pore size is less than 0.1 μm, lithium ions and / or electrolyte cannot move smoothly. When the pore size is greater than 10 μm, the extension of the nonwoven fabric sheet without penetration cannot achieve the effect of the present invention of preventing contact between the anode and cathode.

[0264] Furthermore, the aforementioned nonwoven fabric sheet has a porosity of 40% to 70%. When the porosity is less than 40%, lithium ions and / or electrolyte cannot move smoothly; when the porosity is greater than 70%, the extension of the nonwoven fabric sheet without penetration fails to achieve the effect of preventing contact between the anode and cathode as required by the present invention. The nonwoven fabric sheet manufactured in this way has an air permeability of 1 to 20 seconds per 100 mL.

[0265] Furthermore, the aforementioned nonwoven fabric sheet has a thickness of 10 to 20 μm, but this is only an example and is not limited to this. Depending on the permeability of the nonwoven fabric sheet, nonwoven fabric sheets with thicknesses outside the aforementioned range can be selected.

[0266] The aforementioned nonwoven fabric sheet is bonded to a separation membrane located below the nonwoven fabric sheet by lamination. The lamination is performed in a temperature range of 100 to 150°C. When lamination is performed at a temperature below 100°C, no lamination effect occurs. When lamination is performed at a temperature above 150°C, a portion of the nonwoven fabric will melt.

[0267] The separation membrane of one aspect of the present invention, laminated under the conditions described above, exhibits higher resistivity in terms of relative non-permeability compared to conventional separation membranes made of nonwoven sheets and separation membranes in which a layer comprising inorganic particles is formed on at least one side of a thin film or nonwoven sheet.

[0268] In the aforementioned porous coating, inorganic particles are charged and in contact with each other, and are bonded together by the aforementioned adhesive polymer, thereby forming an interstitial volume between the inorganic particles. The interstitial volume between the inorganic particles becomes an empty space, thus forming pores.

[0269] The inorganic particles used in the formation of the aforementioned porous coating are inorganic particles that do not produce oxidation and / or reduction reactions, added within the operating voltage range of the inorganic particles, i.e., the electrochemical element (e.g., 0–5V based on Li / Li+). In particular, using inorganic particles with ion-transporting capabilities improves the ionic conductivity within the electrochemical element, thereby enhancing performance. Furthermore, using inorganic particles with high dielectric constants helps to increase the dissociation degree of electrolyte salts, such as lithium salts, within the liquid electrolyte, thereby improving the ionic conductivity of the electrolyte.

[0270] For the reasons stated above, the inorganic particles include inorganic particles with a dielectric constant of 5 or higher, preferably 10 or higher, inorganic particles with lithium-ion transport capability, or mixtures thereof.

[0271] Examples of inorganic particles with a dielectric constant of 5 or higher include BaTiO3, Pb(Zr,Ti)O3(PZT), and Pb 1-x La x 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, boehmite (γ-AlOOH), boehmite-like (Al2O3·H2O), diaspore (α-AlO(OH)), bayerite (α-AlO(OH)3), gibbsite (γ-AlOOH3), nordstrandite (AlO(OH)3), etc., aluminum hydroxide or their mixtures, etc.

[0272] In particular, the above-mentioned BaTiO3, Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3 (PLZT), PB(Mg 1 / 3 Nb 2 / 3O3)-PbTiO3 (PMN-PT) and inorganic particles such as hafnium dioxide (HfO2) exhibit high dielectric constant characteristics with a dielectric constant of 100 or more, and have piezoelectricity, which generates charges under a certain pressure in the case of tension or compression and generates a potential difference between the two side faces, thereby preventing short circuits inside the two electrodes caused by external shocks, and thus improving the safety of electrochemical components. In addition, when the above-mentioned high dielectric constant inorganic particles and inorganic particles with lithium ion transport ability are mixed, these enhancement effects will be doubled.

[0273] Inorganic particles with lithium ion transport ability refer to inorganic particles that contain lithium element but do not store lithium and have the function of moving lithium ions. Inorganic particles with lithium ion transport ability transport and move lithium ions due to a kind of defect existing inside the particle structure, thus increasing the lithium ion conductivity in the battery, and thereby improving the battery performance. Examples of inorganic particles with the above-mentioned lithium ion transport ability 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), 14Li2O-9Al2O3-38TiO2-39P2O5, etc., such as LiAlTiP x O ySeries of glass (0 < x < 4, 0 < y < 13), lithium lanthanum titanate (Li x La y TiO3, 0 < x < 2, 0 < y < 3), Li 3.25 Ge 0.25 P 0.75 S4 and other lithium thiophosphates 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 Li3N (Li x N y , 0 < x < 4, 0 < y < 2), SiS2 series glass such as Li3PO4 - Li2S - SiS2 (Li x Si y S z , 0 < x < 3, 0 < y < 2, 0 < z < 4), P2S5 series glass such as LiI - Li2S - P2S5 (Li x P y S z , 0 < x < 3, 0 < y < 3, 0 < z < 7) or their mixtures, etc., but not limited to this.

[0274] In one embodiment of the present invention, the inorganic particles include inorganic particles possessing hydrophilic properties. Inorganic particles possessing such hydrophilic properties include Al2O3 or aluminum hydroxide-based inorganic particles. Examples of aluminum hydroxide-based inorganic particles include boehmite (γ-AlO(OH)), boehm-like particles (Al2O3·H2O), diaspore (α-AlOOH), bayerlite (α-AlO(OH)3), gibbsite (γ-AlO(OH)3), and nordstrandite (AlO(OH)3). In the present invention, the separation membrane includes one or more inorganic particles possessing such hydrophilic properties. In particular, when a hydrophilic organic solvent, such as a carbonate-based organic solvent, is used as the electrolyte, applying inorganic particles possessing such hydrophilic properties to the porous coating of the separation membrane can improve… This invention further improves the electrolyte impregnation of electrode components. In one embodiment, when using a separation membrane substrate made of polyolefin materials, such a substrate exhibits hydrophobic properties, making it difficult to ensure adequate moisture retention through the electrolyte. In this case, by using inorganic particles with hydrophilic properties in the porous coating formed on the surface, the low moisture retention of the separation membrane caused by the hydrophobic nature of the polyolefin-based separation membrane substrate can be prevented. The size of the inorganic particles in the porous coating is not limited, but is preferably 0.001 to 10 μm to form a coating of uniform thickness and appropriate porosity. When the particle size is less than 0.001 μm, the dispersion of the inorganic particles decreases; when it exceeds 10 μm, the increased thickness of the porous coating leads to a decrease in mechanical properties, and the excessively large pore size increases the probability of internal short circuits during battery charging and discharging.

[0275] As an adhesive polymer for forming porous coatings, polymers selected from polyvinylidene fluoride-co-hexafluoropropylene (PVdF), polyvinylidene fluoride-co-trichloroethylene, polymethyl methacrylate, polybutyl acrylate, polyacrylonitrile, polyvinyl pyrrolidone, polyvinyl acetate, polyvinyl-co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetatebutyrate, and cellulose acetate propionate can be used. The adhesive polymer is any one of the following groups: propionate, cyanoethyl pullullan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullullan, and carboxyl methyl cellulose, or a mixture of two or more thereof, but not limited thereto.

[0276] The composition ratio of inorganic particles and binder polymer used in porous coatings is preferably in the range of 50:50 to 99:1, more preferably 70:30 to 95:5. When the ratio of inorganic particles to binder polymer content is less than 50:50, the content of binder polymer increases, and the improvement in the thermal safety of the separation membrane decreases. In addition, the reduction in the space between inorganic particles leads to a decrease in pore size and porosity, ultimately causing a decrease in battery performance. When the content of inorganic particles exceeds 99% by weight, the content of binder polymer is too low, and therefore the resistance to peeling of the porous coating weakens. The thickness of the porous coating is not particularly limited, but is preferably in the range of 0.01 to 20 μm. Furthermore, the pore size and porosity are not particularly limited, but the pore size is preferably in the range of 0.001 to 10 μm, and the porosity is preferably in the range of 10% to 90%. The pore size and porosity are primarily determined by the size of the inorganic particles. For example, when using inorganic particles with a diameter of less than 1 μm, the resulting pores will also be approximately less than 1 μm. This porous structure is then filled with an injected electrolyte, which facilitates ion transport. When the pore size and porosity are less than 0.001 μm and 10% respectively, it can be used as a resistive layer. When the pore size and porosity exceed 10 μm and 90% respectively, the mechanical properties decrease.

[0277] The aforementioned porous coating is formed by adding inorganic particles after dissolving or dispersing the binder polymer in a dispersion medium to obtain a slurry for forming the porous coating, and then applying such a slurry to at least one side of a substrate and drying it. As a dispersion medium, it is preferable to use a binder polymer with a similar solubility index and a low boiling point. This is to ensure uniform mixing and easy removal of the dispersion medium afterwards. Examples of usable dispersion media include, but are not limited to, acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane, water, or mixtures thereof.

[0278] Preferably, inorganic particles are added to the dispersion in which the above-mentioned adhesive polymer is dispersed in a dispersion medium, and then the inorganic particles are crushed. The crushing time is preferably 1 to 20 hours, and as described above, the particle size of the crushed inorganic particles is preferably 0.001 to 10 μm. Regarding the crushing method, general methods can be used, but ball milling is particularly preferred.

[0279] Then, the adhesive polymer dispersion containing inorganic particles is applied to at least one side of the porous polymer substrate under humidity conditions of 10 to 80% and dried. Regarding the method of applying the above dispersion to the porous polymer substrate, conventional coating methods known in the art can be used, such as dip coating, die coating, roll coating, comma coating, or a combination thereof.

[0280] In addition to the aforementioned inorganic particles and adhesive polymers, the porous coating components also include other additives such as conductive agents.

[0281] The final separation membrane produced by this invention has a thickness of 1 to 100 μm or 5 to 50 μm. When the thickness is less than 1 μm, it cannot perform its full separation membrane function, and thermal degradation of mechanical properties occurs. When the thickness exceeds 100 μm, battery characteristics are thermally degraded during efficient charge and discharge. Furthermore, it can possess a porosity of 40 to 60% and a permeability of 150 to 300 seconds / 100 mL.

[0282] According to one embodiment of the present invention, polyethylene or polypropylene series materials are used for the above-mentioned porous polymer substrate. Furthermore, Al oxide or Si oxide series coating materials are used as inorganic particles in the porous coating.

[0283] In the case of the separation membrane exemplified by this invention, porous coatings are provided on both sides of the porous polymer substrate. Therefore, a uniform solid electrolyte interface layer is formed by improving the impregnation performance with the electrolyte, ensuring adequate air permeability compared to conventional cross-sectional inorganic coating separation membranes. For example, this is within 120 s / 100 cc. Furthermore, even with inorganic porous coatings on both sides, the thickness is comparable to that of conventional cross-sectional inorganic coating separation membranes. For example, it is within ~15.0 μm.

[0284] Furthermore, when using the separator membrane of one embodiment of the present invention, the safety of the separator membrane is improved, thereby ensuring heat resistance and compression resistance. Specifically, it ensures heat resistance with a heat shrinkage rate of less than 5% based on 180°C, and ensures a penetration strength of 550 gf or more. In the event of core deformation during battery cycling using such a separator membrane, damage or penetration of the separator membrane can be prevented at the step portion.

[0285] The structure of the electrode assembly according to an embodiment of the present invention will be described in detail below.

[0286] Figure 11This is a cross-sectional view of a gel roll electrode assembly 80, which is cut along the Y-axis direction (winding axis direction) and the electrode plate 40 of the first embodiment is applied to the first electrode plate (anode plate) and the second electrode plate (cathode plate).

[0287] By reference Figure 2 The electrode assembly 80 is manufactured using the winding process described herein. For ease of explanation, the protruding structures of the uncoated portions 43a and 43b extending outward from the separation membrane are shown in detail, while the first electrode plate, the second electrode plate, and the separation membrane winding structure are omitted from the illustration. The uncoated portion 43a, protruding upward, extends from the first electrode plate, and the uncoated portion 43b, protruding downward, extends from the second electrode plate.

[0288] A schematic illustration shows the pattern of height variation of the uncoated portions 43a and 43b. That is, the heights of the uncoated portions 43a and 43b vary irregularly depending on the position of the cut section. For example, when the side portions of the trapezoidal pieces 61 and 61' are cut, the height of the uncoated portion on the section is lower than the height of the pieces 61 and 61'. Therefore, the heights of the uncoated portions 43a and 43b illustrated in the drawing showing the cross-section of the electrode assembly correspond to the heights of the uncoated portions included in each winding coil. Figure 8 C2, Figure 10 The average of D2).

[0289] Reference Figure 11 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 peripheral-side uncoated portion B3 adjacent to the outer peripheral surface of the electrode assembly 80, and an intermediate uncoated portion B2 sandwiched between the core-side uncoated portion B1 and the outer peripheral-side uncoated portion B3.

[0290] The height (length in the Y-axis direction) of the uncoated outer peripheral portion B3 is relatively lower than the height of the uncoated middle portion B2. Therefore, it is possible to prevent a short circuit from occurring inside the battery can when the uncoated outer peripheral portion B3 is pressed against the edge of the battery can.

[0291] The lower uncoated portion 43b has the same structure as the upper uncoated portion 43a. In one variation, the lower uncoated portion 43b has the structure of a conventional electrode plate or the structure of an electrode plate in another embodiment (variant).

[0292] The ends 81 of the upper uncoated portion 43a and the lower uncoated portion 43b are bent from the outer periphery of the electrode assembly 80 toward the core. At this time, the outer periphery uncoated portion B3 is not substantially bent.

[0293] Figure 12This is a cross-sectional view of a gel roll electrode assembly 90, which is cut along the Y-axis direction (winding axis direction) and the electrode plate 45 of the second embodiment is applied to the first electrode plate (anode plate) and the second electrode plate (cathode plate).

[0294] Reference Figure 12 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 peripheral-side uncoated portion B3 adjacent to the outer peripheral surface of the electrode assembly 90, and an intermediate uncoated portion B2 sandwiched between the core-side uncoated portion B1 and the outer peripheral-side uncoated portion B3.

[0295] The height of the uncoated portion B3 on the outer periphery is relatively smaller than the height of the uncoated portion B2 in the middle, and gradually or in stages decreases as it moves from the core side towards the outer periphery. Therefore, it is possible to prevent a short circuit from occurring inside the battery can when the uncoated portion B3 on the outer periphery is pressed against the edge of the battery can.

[0296] The lower uncoated portion 43b has the same structure as the upper uncoated portion 43a. In one variation, the lower uncoated portion 43b has the structure of a conventional electrode plate or the structure of an electrode plate in another embodiment (variant).

[0297] The ends 91 of the upper uncoated portion 43a and the lower uncoated portion 43b are bent from the outer periphery of the electrode assembly 90 toward the core. At this time, the outermost 92 of the outer periphery uncoated portion B3 is not bent.

[0298] Figure 13 It is a cross-sectional view of a gel roll electrode assembly 100, which is made by cutting any one of the electrode plates 50, 60, and 70 of the third to fifth embodiments (variations thereof) along the Y-axis direction (winding axis direction) and is suitable for the first electrode plate (anode plate) and the second electrode plate (cathode plate).

[0299] Reference Figure 13 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 peripheral-side uncoated portion B3 adjacent to the outer peripheral surface of the electrode assembly 100, and an intermediate uncoated portion B2 sandwiched between the core-side uncoated portion B1 and the outer peripheral-side uncoated portion B3.

[0300] The height of the uncoated portion B1 on the core side is relatively lower than the height of the uncoated portion B2 in the middle. Furthermore, the height of the innermost uncoated portion 43a in the middle uncoated portion B2 is less than or equal to the radial length R of the uncoated portion B1 on the core side. Here, the height of the uncoated portion refers to the length from the reference line DL to the first side or the height of the slice.

[0301] Therefore, even if the uncoated portion B2 is bent, the bent portion will not block the core cavity 102 of the electrode assembly 100. If the cavity 102 is not blocked, there are no difficulties in the electrolyte injection process, and the electrolyte injection efficiency can be improved. Furthermore, the welding process between the cathode-side current collector and the battery canister is easily performed by inserting the welding fixture through the cavity 102.

[0302] The height of the uncoated outer peripheral portion B3 is relatively lower than the height of the uncoated middle portion B2. Therefore, it is possible to prevent a short circuit from occurring inside the battery can when the uncoated outer peripheral portion B3 is pressed against the edge of the battery can.

[0303] In a variation, with Figure 13 Unlike the cases shown, the height of the uncoated portion B3 on the outer periphery gradually or in stages decreases. Additionally, in... Figure 13 In the middle, the height of the uncoated middle portion B2 is the same on a part of the outer periphery, but the height of the uncoated middle portion B2 gradually or in stages increases from the boundary between the uncoated middle portion B1 on the core side and the uncoated middle portion B2 to the boundary between the uncoated middle portion B2 and the uncoated outer periphery portion B3.

[0304] The lower uncoated portion 43b has the same structure as the upper uncoated portion 43a. In one variation, the lower uncoated portion 43b has the structure of a conventional electrode plate or the structure of an electrode plate in another embodiment (variant).

[0305] The ends 101 of the upper uncoated portion 43a and the lower uncoated portion 43b are bent from the outer periphery of the electrode assembly 100 toward the core. At this time, the core-side uncoated portion B1 and the outer periphery-side uncoated portion B3 are not substantially bent.

[0306] When the uncoated portion B2 comprises multiple segments, bending stress is relieved, preventing the groove portion of the uncoated portion 43 from tearing or abnormally deforming. Furthermore, when the segment width and / or height and / or spacing are adjusted according to the numerical range of the above embodiment, the segments are bent towards the core side, overlapping in multiple layers to ensure sufficient weld strength, forming empty holes (voids) on the bending surface (the surface viewed from the Y-axis).

[0307] Figure 14 This is a cross-sectional view of the electrode assembly 110 of another embodiment of the present invention, cut along the Y-axis direction (winding axis direction).

[0308] Reference Figure 14 Electrode assembly 110 and Figure 13 Compared to the electrode assembly 100, the structure is substantially the same except that the height of the uncoated portion B3 on the outer periphery is substantially the same as the height of the outermost part of the uncoated portion B2 in the middle.

[0309] The uncoated portion B3 on the outer periphery includes multiple segments. The structure of the multiple segments is substantially the same as that described in the fourth and fifth embodiments (modified examples).

[0310] In the electrode assembly 110, the height of the uncoated portion B1 on the core side is relatively lower than the height of the uncoated portion B2 in the middle. Furthermore, in the uncoated portion B2 in the middle, the height H of the innermost uncoated portion is less than or equal to the radial length R of the uncoated portion B1 on the core side. Here, the height of the uncoated portion refers to the length from the reference line DL to the first side or the height of the section.

[0311] Therefore, even if the uncoated portion B2 is bent, the bent portion does not block the core cavity 112 of the electrode assembly 110. When the cavity 112 is not blocked, there is no difficulty in the electrolyte injection process, improving the electrolyte injection efficiency. In addition, the welding process between the cathode-side current collector and the battery canister can be easily performed by inserting a welding fixture through the cavity 112.

[0312] In one variation, the structure in which the height of the intermediate uncoated portion B2 gradually or progressively increases from the core side to the outer periphery extends to the outer periphery uncoated portion B3. In this case, the height of the uncoated portion 43a gradually or progressively increases from the boundary between the core-side uncoated portion B1 and the intermediate uncoated portion B2 to the outermost surface of the electrode assembly 110.

[0313] The lower uncoated portion 43b has the same structure as the upper uncoated portion 43a. In one variation, the lower uncoated portion 43b has the structure of a conventional electrode plate or the structure of an electrode plate in another embodiment (variant).

[0314] The ends 111 of the upper uncoated portion 43a and the lower uncoated portion 43b are bent from the outer periphery of the electrode assembly 110 toward the core side. At this time, the core-side uncoated portion B1 is not bent.

[0315] When the uncoated middle portion B2 and the uncoated outer peripheral portion B3 include multiple segments, bending stress is relieved, preventing the uncoated portions 43a and 43b around the groove from being torn or abnormally deformed. Furthermore, when the segment width and / or height and / or spacing are adjusted according to the numerical range of the above embodiment, the segments are bent towards the core side and overlapped in multiple layers to sufficiently ensure welding strength, without forming holes (voids) on the bending surface (the surface viewed from the Y-axis).

[0316] Figure 15 This is a cross-sectional view of the electrode assembly 120 of another embodiment of the present invention cut along the Y-axis direction (winding axis direction).

[0317] Reference Figure 15 Electrode assembly 120 and Figure 13 Compared to the electrode assembly 100, the only difference is that the height of the uncoated middle portion B2 has a pattern of gradually or stepwise increasing and then decreasing; the rest of the structure is essentially the same.

[0318] Such a change in the height of the uncoated intermediate portion B2 is achieved by adjusting the stepped pattern included in the uncoated intermediate portion B2 (see reference). Figure 6 ) or screenshot (refer to) Figure 7a or Figure 9a It is reflected in the height of ).

[0319] In the electrode assembly 120, the height of the core-side uncoated portion B1 is relatively lower than the height of the intermediate uncoated portion B2. Furthermore, the height H of the innermost uncoated portion in the intermediate uncoated portion B2 is less than or equal to the radial length R of the core-side uncoated portion B1. Here, the height of the uncoated portion refers to the length from the reference line DL to the first side portion or the height of the section.

[0320] Therefore, even if the uncoated portion B2 bends towards the core, the bend will not block the core cavity 122 of the electrode assembly 120. When the cavity 122 is not blocked, there is no difficulty in the electrolyte injection process, improving the electrolyte injection efficiency. In addition, the welding process between the cathode-side current collector and the battery canister can be easily performed by inserting a welding fixture through the cavity 122.

[0321] Furthermore, the height of the uncoated portion B3 on the outer periphery is relatively lower than the height of the uncoated portion B2 in the middle. Therefore, it is possible to prevent a short circuit from occurring inside when the uncoated portion B3 on the outer periphery is pressed against the edge of the battery can. In a modified example, the height of the uncoated portion B3 on the outer periphery gradually or in stages towards the outer periphery.

[0322] The lower uncoated portion 43b has the same structure as the upper uncoated portion 43a. In a modified example, the lower uncoated portion 43b has the structure of a conventional electrode plate or the structure of an electrode plate in another embodiment (modified example).

[0323] The ends 121 of the upper uncoated portion 43a and the lower uncoated portion 43b are bent from the outer periphery of the electrode assembly 120 toward the core. At this time, the core-side uncoated portion B1 and the outer periphery-side uncoated portion B3 are not substantially bent.

[0324] When the uncoated portion B2 comprises multiple segments, bending stress is relieved, preventing the uncoated portions 43a and 43b from tearing or undergoing abnormal deformation. Furthermore, when the segment width and / or height and / or spacing are adjusted according to the numerical range of the above embodiment, the segments are bent towards the core side and overlapped in multiple layers to sufficiently ensure weld strength, without forming empty holes (voids) on the bending surface (the surface viewed from the Y-axis).

[0325] Figure 16 This is a cross-sectional view of the electrode assembly 130 of another embodiment of the present invention, cut along the Y-axis direction (winding axis direction).

[0326] Reference Figure 16 Electrode assembly 130 and Figure 15 Compared to electrode assembly 120, the height of the uncoated portion B3 on the outer periphery side has a pattern that gradually or gradually decreases as it approaches the outermost surface of electrode assembly 130 from the boundary position between the uncoated portion B3 on the outer periphery side and the uncoated portion B2 in the middle. The rest of the structure is substantially the same.

[0327] Such a height variation of the uncoated outer peripheral portion B3 is achieved through a stepped pattern included in the intermediate uncoated portion B2 (see reference). Figure 6 The pattern height is extended to the uncoated portion B3 on the outer periphery, and the pattern height gradually or gradually decreases as it approaches the outer periphery. In another variation, the height variation of the uncoated portion B3 on the outer periphery is achieved by extending the segment structure of the uncoated portion B2 in the middle to the uncoated portion B3 on the outer periphery, and the height of the segment gradually or gradually decreases as it approaches the outer periphery.

[0328] In the electrode assembly 130, the height of the uncoated portion B1 on the core side is relatively lower than the height of the uncoated portion B2 in the middle. Furthermore, the height H of the innermost uncoated portion in the middle uncoated portion B2 is less than or equal to the radial length R of the uncoated portion B1 on the core side. Here, the height of the uncoated portion refers to the length from the reference line DL to the first side or the height of the section.

[0329] Therefore, even if the uncoated portion B2 is bent towards the core, the bent portion does not block the core cavity 132 of the electrode assembly 120. Without blocking the cavity 132, there are no difficulties in the electrolyte injection process, improving electrolyte injection efficiency. Furthermore, the welding process between the cathode-side current collector and the battery canister is easily performed by inserting the welding fixture through the cavity 132.

[0330] The lower uncoated portion 43b has the same structure as the upper uncoated portion 43a. In one variation, the lower uncoated portion 43b has the structure of a conventional electrode plate or the structure of an electrode plate in another embodiment (variant).

[0331] The ends 131 of the upper uncoated portion 43a and the lower uncoated portion 43b are bent from the outer periphery of the electrode assembly 130 toward the core. At this time, the uncoated portion B1 on the core side is not bent.

[0332] When the uncoated middle portion B2 and the uncoated outer peripheral portion B3 include multiple segments, bending stress is relieved, preventing the groove portions of the uncoated portions 43a and 43b from tearing or abnormally deforming. Furthermore, when the segment width and / or height and / or spacing are adjusted according to the numerical range of the above embodiments, the segments are bent towards the core side and overlapped in multiple layers to sufficiently ensure welding strength, without forming empty holes (voids) on the bending surface (the surface viewed from the Y-axis).

[0333] The various electrode assembly structures of the embodiments of the present invention are applicable to gel roll-type cylindrical battery cells.

[0334] Preferably, the cylindrical battery cell is, for example, a cylindrical battery cell with a shape factor ratio (defined as the ratio of the diameter of the cylindrical battery cell to its height, i.e., the ratio of diameter Φ to height H) that is approximately greater than 0.4.

[0335] Here, the shape factor refers to the value representing the diameter and height of the cylindrical battery cell. One embodiment of the cylindrical battery cell of this invention includes, for example, 46110 cells, 48750 cells, 48110 cells, 48800 cells, and 46800 cells. In the shape factor value, the first two digits represent the diameter of the unit, the next two digits represent the height of the unit, and the final digit 0 indicates that the unit cross-section is circular.

[0336] When using electrode assemblies with tabless structures in cylindrical battery cells with a shape factor ratio exceeding 0.4, the stress applied radially when bending the uncoated portion increases, making it prone to tearing. Furthermore, to ensure sufficient weld strength and reduce resistance when welding the current collector to the bent surface of the uncoated portion, it is necessary to significantly increase the number of overlapping layers of the uncoated portion. These requirements are met by the electrode plate and electrode assembly of the embodiments (modified examples) of the present invention.

[0337] One embodiment of the present invention is a cylindrical battery cell with a diameter of approximately 46 mm, a height of approximately 110 mm, and a shape factor ratio of 0.418.

[0338] Another embodiment of the battery cell is a cylindrical battery cell that is generally cylindrical in shape, with a diameter of approximately 48 mm, a height of approximately 75 mm, and a shape factor ratio of 0.640.

[0339] Another embodiment of the battery cell is a cylindrical battery cell with a diameter of approximately 48 mm, a height of approximately 110 mm, and a shape factor ratio of 0.418.

[0340] Another embodiment of the battery cell is a cylindrical battery cell with a diameter of approximately 48 mm, a height of approximately 80 mm, and a shape factor ratio of 0.600.

[0341] Another embodiment of the battery cell is a cylindrical battery cell with a diameter of approximately 46 mm, a height of approximately 80 mm, and a shape factor ratio of 0.575.

[0342] Previously, battery cells with a shape factor ratio of approximately 0.4 or less were used. That is, examples include 18650 cells and 21700 cells. In the case of an 18650 cell, its diameter is approximately 18 mm, its height is approximately 65 mm, and its shape factor ratio is 0.277. In the case of a 21700 cell, its diameter is approximately 21 mm, its height is approximately 70 mm, and its shape factor ratio is 0.300.

[0343] The cylindrical battery cell of the present invention will now be described in detail according to an embodiment of the present invention.

[0344] Figure 17 This is a cross-sectional view of a cylindrical battery cell 140 of an embodiment of the present invention cut along the Y-axis direction.

[0345] Reference Figure 17 According to one embodiment of the present invention, the cylindrical battery cell 140 includes a first electrode plate, an electrode assembly 141 including a separation membrane and a second electrode plate, a battery can 142 for housing the electrode assembly 141, and a sealing body 143 for sealing the open end of the battery can 142.

[0346] The battery canister 142 is a cylindrical container with an opening at the top. The battery canister 142 is made of a conductive metal such as aluminum or steel. The electrode assembly 10 and the electrolyte are housed within the inner space of the battery canister 142 through the opening at the top.

[0347] Electrolytes can be those with A + B - Salts with similar structures. Among them, A... + Including Li + Na + K + Ions consisting of basic metal cations or combinations thereof. Additionally, B... - Including the choice 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 - Any one or more anions that constitute a group.

[0348] Electrolytes can also be used dissolved in organic solvents. As for organic solvents, any solvent that can be used as a solvent for electrolytes in electrochemical components is not limited to a specific component. Examples include carbonate solvents such as propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), and dipropyl carbonate (DPC), as well as dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methylpyrrolidone (NMP), ethyl methyl carbonate (EMC), γ-butyrolactone, or mixtures thereof.

[0349] The electrode assembly 141 has a gel roll shape. For example... Figure 2 As shown, the electrode assembly 141 is made by winding the laminate with the winding center C as a reference. The laminate is formed by sequentially stacking the lower separation film, the first electrode plate, the upper separation film and the second electrode plate at least once.

[0350] The first electrode plate and the second electrode plate have different polarities. That is, one is anode and the other is cathode. At least one of the first electrode plate and the second electrode plate has the structure of the electrode plate in the above embodiment (modified example). In addition, the other of the first electrode plate and the second electrode plate has the structure of a conventional electrode plate or the structure of the electrode plate in the embodiment (modified example).

[0351] The electrode assembly 141 has an uncoated portion 146a of the first electrode and an uncoated portion 146b of the second electrode protruding from its upper and lower parts, respectively. The first electrode has the electrode structure of the first embodiment (modified example). Therefore, the height of the uncoated portion B3 on the outer periphery of the uncoated portion 146a of the first electrode is lower than the height of the uncoated portion of the other parts. The uncoated portion B3 on the outer periphery is separated from the inner peripheral surface of the battery can 142, particularly the rolled edge portion 147, by a predetermined distance. Therefore, the uncoated portion B3 on the outer periphery of the first electrode does not contact the battery can 142, which is electrically connected to the second electrode, thereby preventing a short circuit inside the battery 140.

[0352] The uncoated portion 146b of the second electrode has the same height. In a modified example, the uncoated portion 146b of the second electrode has the same structure as the uncoated portion 146a of the first electrode. In other modified examples, the uncoated portion 146b of the second electrode may optionally have the uncoated portion structure of the electrode in the embodiment (modified example).

[0353] The sealing body 143 includes a cover plate 143a, a first gasket 143b that provides airtightness and insulation between the cover plate 143a and the battery canister 142, and a connecting plate 143c that is electrically and mechanically connected to the cover plate 143a.

[0354] The cover plate 143a is a component made of conductive metal and covers the upper open portion of the battery canister 142. The cover plate 143a is electrically connected to the uncoated portion 146a of the first electrode and is electrically insulated from the battery canister 142 by a first gasket 143b. Therefore, the cover plate 143a is used as the first electrode terminal of the cylindrical battery 140.

[0355] A cover plate 143a is mounted on the rolled edge portion 147 formed on the battery can 142 and is fixed by a crimping portion 148. To ensure the airtightness of the battery can 142 and to achieve electrical insulation between the battery can 142 and the cover plate 143a, a first washer 143b is sandwiched between the cover plate 143a and the crimping portion 148. The cover plate 143a has a protrusion 143d that protrudes upward from its center.

[0356] The battery canister 142 is electrically connected to the uncoated portion 146b of the second electrode. Therefore, the battery canister 142 has the same polarity as the second electrode. When the second electrode has a negative polarity, the battery canister 142 also has a negative polarity.

[0357] The battery can 142 has a rolled edge portion 147 and a crimping portion 148 at its upper end. The rolled edge portion 147 is formed by pressing the outer peripheral surface of the battery can 142 inward. The rolled edge portion 147 prevents the electrode assembly 141 housed inside the battery can detach through the upper opening of the battery can 142 and serves as a support for mounting the sealing body 143.

[0358] The inner circumferential surface of the rolled edge portion 147 is spaced apart from the uncoated outer circumferential portion B3 of the first electrode by a predetermined distance. More specifically, the lower end of the inner circumferential surface of the rolled edge portion 147 is spaced apart from the uncoated outer circumferential portion B3 of the first electrode by a predetermined distance. Furthermore, because the uncoated outer circumferential portion B3 is low in height, it is substantially unaffected when the battery can 142 is pressed in from the outside to form the rolled edge portion 147. Therefore, the uncoated outer circumferential portion B3 is not pressed by the rolled edge portion 147 or other components, thereby preventing partial deformation of the electrode assembly 141 and thus preventing short circuits inside the cylindrical battery 140.

[0359] Preferably, when the pressing depth of the rolled edge 147 is defined as D1, and the radial length from the inner circumferential surface of the battery can 142 to the boundary between the outer peripheral uncoated portion B3 and the middle uncoated portion B2 is defined as D2, the relationship D1≤D2 is satisfied. In this case, damage to the outer peripheral uncoated portion B3 can be substantially prevented when pressing the rolled edge 147 into the battery can 142.

[0360] A crimping portion 148 is formed on the upper part of the rolled edge portion 147. The crimping portion 148 has a shape that extends and bends to surround the outer peripheral surface of the cover plate 143a disposed on the rolled edge portion 147 and a portion of the upper surface of the cover plate 143a.

[0361] The cylindrical battery cell 140 also includes a first current collector 144 and / or a second current collector 145 and / or an insulator 146.

[0362] The first current collector 144 is attached to the upper part of the electrode assembly 141. The first current collector 144 is made of a conductive metal such as aluminum, copper, or nickel, and is electrically connected to the uncoated portion 146a of the first electrode plate. A lead 149 is connected to the first current collector 144. The lead 149 extends from the top of the electrode assembly 141 and is attached to the connecting plate 143c or directly to the lower surface of the cover plate 143a. The lead 149 is joined to other components by welding.

[0363] Preferably, the first collector plate 144 and the lead 149 are integrally formed. In this case, the lead 149 has a long plate shape extending outward from the center of the first collector plate 144.

[0364] The first current collector 144 has a plurality of radial protrusions and recesses (not shown) on its lower surface. With the radial protrusions and recesses, pressing the first current collector 144 presses the protrusions and recesses into the uncoated portion 146a of the first electrode.

[0365] The first current collector 144 is bonded to the end of the uncoated portion 146a of the first electrode. For example, the bonding between the uncoated portion 146a and the first current collector 144 is achieved by laser welding. Laser welding can be performed by partially melting the base material of the current collector. In a modified example, welding between the first current collector 144 and the uncoated portion 146a is performed while solder is being held between the current collector 144 and the uncoated portion 146a. In this case, the solder has a lower melting point than the current collector 144 and the uncoated portion 146a. Laser welding can be replaced by resistance welding, ultrasonic welding, etc.

[0366] The second current collector 145 is bonded to the lower surface of the electrode assembly 141. One side of the second current collector 145 is bonded to the uncoated portion 146b of the second electrode by welding, and the opposite side is bonded to the inner bottom surface of the battery canister 142 by welding. The bonding structure between the second current collector 145 and the uncoated portion 146b of the second electrode plate is substantially the same as the bonding structure between the first current collector 144 and the uncoated portion 146a of the first electrode plate.

[0367] The uncoated portions 146a and 146b are not limited to the structures shown in the figures. Therefore, the uncoated portions 146a and 146b may selectively possess the conventional uncoated portion structure and the uncoated portion structure of the electrode plate in the embodiments (modified examples).

[0368] An insulator 146 covers the first current collector 144. The insulator 146 covers the upper surface of the first current collector 144, thereby preventing direct contact between the first current collector 144 and the inner circumferential surface of the battery canister 142.

[0369] The insulator 146 has a lead hole 151 for leading out a lead 149 extending upward from the first current collector 144. The lead 149 is led out upward through the lead hole 151 and attached to the lower surface of the connecting plate 143c or the lower surface of the cover plate 143a.

[0370] The area around the edge of the insulator 146 is sandwiched between the first current collector 144 and the rolled edge 147, fixing the assembly of the electrode assembly 141 and the first current collector 144. Thus, the assembly of the electrode assembly 141 and the first current collector 144 restricts the vertical movement of the battery cell 140, thereby improving the assembly safety of the battery cell 140.

[0371] The insulator 146 is made of a polymer resin with insulating properties. In one example, the insulator 146 is made of polyethylene, polypropylene, polyimide, or polybutylene phthalate.

[0372] The battery canister 142 also includes a vent 152 formed on its lower surface. The vent 152 corresponds to a region on the lower surface of the battery canister 142 that is thinner than the surrounding region. The vent 152 is structurally more fragile than the surrounding region. Therefore, when an abnormality occurs in the cylindrical battery cell 140 and the internal pressure rises above a certain level, the vent 152 ruptures, and the gas generated inside the battery canister 142 is discharged to the outside.

[0373] The vent 152 is formed continuously or discontinuously in a circular pattern on the lower surface of the battery can 142. In a modified example, the vent 152 is formed as a straight line pattern or other patterns.

[0374] Figure 18This is a cross-sectional view of a cylindrical battery cell 150 of another embodiment of the present invention cut along the Y-axis direction.

[0375] Reference Figure 18 Cylindrical battery cell 150 and Figure 17 Compared to the cylindrical battery 140, the structure is substantially the same except that the uncoated portion 146a of the first electrode adopts the structure of the electrode plate of the second embodiment (modified example).

[0376] Reference Figure 18 The uncoated portion 146a of the first electrode has a shape in which the height of the uncoated portion B3 on the outer periphery gradually or in stages decreases as it approaches the inner periphery of the battery can 142. Preferably, the virtual line connecting the uppermost end of the uncoated portion B3 on the outer periphery has the same or similar shape as the inner periphery of the rolled edge portion 147.

[0377] The uncoated portion B3 on the outer periphery is formed with an inclined surface. Therefore, it is possible to prevent the uncoated portion B3 on the outer periphery from being damaged by the crimped portion 147 when the battery can 142 is pressed in to form the crimped portion 147. In addition, it is possible to suppress the phenomenon of short circuits occurring internally due to contact between the uncoated portion B3 on the outer periphery and the battery can 142 with different polarities.

[0378] The remaining structure of the cylindrical battery cell 150 is substantially the same as that of the embodiment (modified example) described above.

[0379] The uncoated portions 146a and 146b are not limited to the structures shown in the figures. Therefore, the uncoated portions 146a and 146b selectively possess the conventional uncoated portion structure and the uncoated portion structure of the electrode plate in the embodiments (modified examples).

[0380] Figure 19 This is a cross-sectional view of a cylindrical battery cell 160 of another embodiment of the present invention, cut along the Y-axis direction.

[0381] Reference Figure 19 Compared with the cylindrical batteries 140 and 150 described above, the cylindrical battery unit 160 differs in that the lead 149 connected to the first current collector 144 is directly connected to the cover plate 143a of the sealing body 143 through the lead hole 151 of the insulator 146, and the insulator 146 and the first current collector 144 are in close contact with the lower surface of the cover plate 143a. The rest of the structures are substantially the same.

[0382] In the cylindrical battery cell 160, the diameter of the first current collector 144 and the outermost diameter of the uncoated portion B2 are smaller than the minimum inner diameter of the battery canister 142. Furthermore, the diameter of the first current collector 144 is greater than or equal to the outermost diameter of the uncoated portion B2.

[0383] Specifically, the minimum inner diameter of the battery can 142 corresponds to the inner diameter of the battery can 142 at the location where the rolled edge portion 147 is formed. At this time, the outermost diameter of the first current collector 144 and the outermost diameter of the uncoated intermediate portion B2 are smaller than the inner diameter of the battery can 142 at the location where the rolled edge portion 147 is formed. Furthermore, the diameter of the first current collector 144 is greater than or equal to the outermost diameter of the uncoated intermediate portion B2. The area surrounding the edge of the insulator 146 is bent downwards and sandwiched between the uncoated outer peripheral portion B3 and the rolled edge portion 147, thereby securing the assembly of the electrode assembly 141 and the first current collector 144.

[0384] Preferably, the insulator 146 includes a portion covering the uncoated outer peripheral portion B3 and a portion covering the first current collector 144, and the portion connecting the two portions has a shape that is bent together with the curled edge portion 147 in accordance with the bending shape of the curled edge portion 147. The insulator 146 insulates the uncoated outer peripheral portion B3 and the inner peripheral surface of the curled edge portion 147, while also insulating the inner peripheral surface of the first current collector 144 and the curled edge portion 147.

[0385] The first current collector 144 is positioned higher than the lower end of the rolled edge portion 147, and is attached to the core-side uncoated portion B1 and the intermediate uncoated portion B2. At this time, the pressing depth D1 of the rolled edge portion 147 is less than or equal to the distance D2 from the inner circumferential surface of the battery can 142 to the boundary of the outer circumferential 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 144 attached to them are positioned higher than the lower end of the rolled edge portion 147. The lower end of the rolled edge portion 147 refers to the baseline portion between the part of the battery can 142 that houses the electrode assembly 141 and the rolled edge portion 147.

[0386] The uncoated portion B1 on the core side and the uncoated portion B2 in the middle occupy the inner space in the radial direction of the rolled edge portion 147, thus minimizing the empty space between the electrode assembly 141 and the cover plate 143a. Furthermore, the connecting plate 143c, which occupies the empty space between the electrode assembly 141 and the cover plate 143a, is omitted. Therefore, the lead 149 of the first electrode plate 144 is directly bonded to the lower surface of the cover plate 143a. With the structure described above, the empty space within the battery cell is reduced, and the energy density is maximized correspondingly to the reduced empty space.

[0387] In the cylindrical battery cell 160, the first current collector 144 and the second current collector 145 are welded to the ends of the uncoated portions 146a and 146b in the same manner as in the above embodiment.

[0388] The uncoated portions 146a and 146b are not limited to the structures shown in the figures. Therefore, the uncoated portions 146a and 146b selectively possess the conventional uncoated portion structure and the uncoated portion structure of the electrode plate in the embodiments (modified examples).

[0389] Figure 20 This is a cross-sectional view of a cylindrical battery cell 170 of another embodiment of the present invention, cut along the Y-axis.

[0390] Reference Figure 20 Cylindrical battery cell 170 and Figure 17 The cylindrical battery cell 140 shown is substantially the same in structure as the electrode assembly, with differences only in the points where the structure is changed except for the electrode assembly.

[0391] Specifically, the cylindrical battery cell 170 includes a battery can 171 with a through-hole having a rivet terminal 172. The rivet terminal 172 is located on the closed surface (upper surface of the figure) of the battery can 171. The rivet terminal 172 is riveted to the through-hole of the battery can 171 while being clamped by an insulating second washer 173. The rivet terminal 172 protrudes to the outside in the direction of gravity and the opposite direction.

[0392] The rivet terminal 172 includes a terminal protrusion portion 172a and a terminal insertion portion 172b. The terminal protrusion portion 172a protrudes to the outside of the closed surface of the battery can 171. The terminal protrusion portion 172a is located approximately at the center of the closed surface of the battery can 171. The maximum diameter of the terminal protrusion portion 172a is larger than the maximum diameter of the through hole formed in the battery can 171. The terminal insertion portion 172b penetrates approximately at the center of the closed surface of the battery can 171 and is electrically connected to the uncoated portion 146a of the first electrode plate. The terminal insertion portion 172b is rivet-attached to the inner surface of the battery can 171. That is, the end of the terminal insertion portion 172b has a twisted shape toward the inner surface of the battery can 171. The maximum diameter of the end of the terminal insertion portion 172b is larger than the maximum diameter of the through hole in the battery can 171.

[0393] The lower end face of the terminal insertion portion 172b is welded to the first current collector plate 144, which is connected to the uncoated portion 146a of the first electrode plate. An insulating cover 174 made of insulating material is sandwiched between the first current collector plate 144 and the inner side of the battery can 171. The insulating cover 174 covers the upper part of the first current collector plate 144 and the upper edge of the electrode assembly 141. This prevents a short circuit caused by contact between the uncoated portion B3 on the outer periphery of the electrode assembly 141 and the inner side of the battery can 171, which has different polarities. The terminal insertion portion 172b of the rivet terminal 172 passes through the insulating cover 174 and is welded to the first current collector plate 144.

[0394] The second washer 173 is sandwiched between the battery can 171 and the rivet terminal 172 to prevent the battery can 171 and the rivet terminal 172, which have opposite polarities, from making electrical contact with each other. Thus, the upper surface of the battery can 171, which has a generally flat shape, is used as the second electrode terminal of the cylindrical battery cell 170.

[0395] The second washer 173 includes a washer protrusion 173a and a washer insertion portion 173b. The washer protrusion 173a is sandwiched between the terminal protrusion 172a of the rivet terminal 172 and the battery can 171. The washer insertion portion 173b is sandwiched between the terminal insertion portion 172b of the rivet terminal 172 and the battery can 171. The washer insertion portion 173b is deformed together with the terminal insertion portion 172b and fits tightly against the inner surface of the battery can 171. The second washer 173 is, for example, made of an insulating polymer resin.

[0396] The washer protrusion 173a of the second washer 173 extends in a manner that covers the outer peripheral surface of the terminal protrusion 172a of the rivet terminal 172. When the second washer 173 covers the outer peripheral surface of the rivet terminal 172, it can prevent short circuits from occurring during the process of attaching electrical connection components such as busbars to the upper surface of the battery can 171 and / or the rivet terminal 172. Although not shown, the washer protrusion 173a extends in a manner that covers both the outer peripheral surface and a portion of the upper surface of the terminal protrusion 172a.

[0397] When the second gasket 173 is made of polymer resin, it is bonded to the battery can 171 and the rivet terminal 172 by heat fusion. In this case, the airtightness of the interface between the second gasket 173 and the rivet terminal 172, and between the second gasket 173 and the battery can 171, can be enhanced. On the other hand, when the gasket protrusion 173a of the second gasket 173 has a shape that extends to the upper surface of the terminal protrusion 172a, the rivet terminal 172 is integrally bonded to the second gasket 173 by insert molding.

[0398] The remaining area 175 on the upper surface of the battery can 171, excluding the area occupied by the rivet terminal 172 and the second washer 173, corresponds to a second electrode terminal having the opposite polarity to the rivet terminal 172.

[0399] The second current collector 176 is attached to the lower part of the electrode assembly 141. The second current collector 176 is made of conductive metals such as aluminum, steel, copper, and nickel and is electrically connected to the uncoated part 146b of the second electrode.

[0400] Preferably, the second current collector 176 is electrically connected to the battery canister 171. For this purpose, at least a portion of the edge of the second current collector 176 is fixed between the inner side of the battery canister 171 and the first washer 178b. In one example, at least a portion of the edge of the second current collector 176 is fixed to the rolled edge 17 by welding while supported on the lower end face of the rolled edge 180 formed at the lower end of the battery canister 171. In a modified example, at least a portion of the edge of the second current collector 176 is directly welded to the inner wall surface of the battery canister 171.

[0401] The second current collector 176 has a plurality of radial protrusions and recesses (not shown) formed on the surface opposite to the uncoated portion 146b. When the protrusions and recesses are formed, pressing the second current collector 176 will press the protrusions and recesses into the uncoated portion 146b.

[0402] Preferably, the ends of the second current collector 176 and the uncoated portion 146b are joined by welding, for example by laser welding.

[0403] The sealing body 178, which seals the lower open end of the battery canister 171, includes a cover plate 178a and a first gasket 178b. The first gasket 178b electrically separates the cover plate 178a and the battery canister 171. A crimping portion 181 secures the edge of the cover plate 178a and the first gasket 178b together. The cover plate 178a has a ventilation portion 179. The structure of the ventilation portion 179 is substantially the same as that in the above-described embodiment (modified example).

[0404] Preferably, the cover plate 178a is made of a conductive metal material. However, since the cover plate 178a and the battery canister 171 are sandwiched by a first gasket 178b, the cover plate 178a does not have electrical polarity. The sealing body 178 seals the lower opening of the battery canister 171 and functions to release gas when the internal pressure of the battery cell 170 increases to a threshold value.

[0405] Preferably, the rivet terminal 172, which is electrically connected to the uncoated portion 146a of the first electrode plate, is used as the first electrode terminal. Additionally, the portion 175 of the upper surface of the battery can 171, which is electrically connected to the uncoated portion 146b of the second electrode plate via the second current collector 176, excluding the rivet terminal 172, is used as a second electrode terminal with a polarity different from the first electrode terminal. Thus, with both electrode terminals located at the upper part of the cylindrical battery cell 170, electrical connection components such as busbars can be arranged only on one side of the cylindrical battery cell 170. This simplifies the battery pack structure and increases energy density. Furthermore, the portion 175 used as the second electrode terminal has a generally flat shape, ensuring sufficient contact area when joining electrical connection components such as busbars. Therefore, the cylindrical battery cell 170 can reduce the resistance at the contact points of the electrical connection components to a preferred level.

[0406] Furthermore, the structure of the electrode assembly 141 and the structure of the uncoated portion are not limited to the situation shown in the figure, and can be replaced by the structure of the above embodiment (modified example).

[0407] Figure 21 This is a cross-sectional view of a cylindrical battery cell 180 of another embodiment of the present invention, cut along the Y-axis.

[0408] Reference Figure 21 Cylindrical battery cell 180 and Figure 18 Compared to the cylindrical battery cell 150 shown, the electrode assembly 141 has a substantially identical structure, except for the electrode assembly 141 itself. Figure 20 The cylindrical battery cell 170 shown is essentially the same.

[0409] Therefore, the structure of the embodiments (modifications) of cylindrical battery cells 150 and 170 is also applicable to cylindrical battery cell 180.

[0410] Furthermore, the structure of the electrode assembly 141 and the structure of the uncoated portion are not limited to the structure shown in the figure, and can be replaced by the structure of the above embodiment (modified example).

[0411] Figure 22 This is a cross-sectional view of a cylindrical battery cell 190 of another embodiment of the present invention, cut along the Y-axis.

[0412] Reference Figure 22 The cylindrical battery cell 190 includes Figure 14 The electrode assembly 110 shown, except for the electrode assembly 110 itself, has the same structure as... Figure 17 The cylindrical battery cell 140 shown is essentially the same.

[0413] Reference Figure 22 The uncoated portions 146a and 146b of the electrode assembly 110 are bent from the outer periphery towards the core. At this time, the uncoated portion B1 on the core side is lower in height than the other portions, so it is not substantially bent. The first current collector 144 is welded to the bent surface of the uncoated portion 146a, and the second current collector 145 is welded to the bent surface of the uncoated portion 146b. The bent surfaces are formed in multiple layers on the upper and lower parts of the electrode assembly 110, respectively, when the uncoated portions 146a and 146b are bent.

[0414] The height of the uncoated portion B1 on the core side of the electrode assembly 110 is relatively lower than that of other portions. Additionally, as... Figure 14 As shown, the height H of the innermost uncoated portion in the middle uncoated portion B2 is less than or equal to the radial length R of the core-side uncoated portion B1. Here, the height of the uncoated portion refers to the length from the reference line DL to the first side or the height of the slice.

[0415] Therefore, even if the uncoated portion 146a is bent toward the core, the cavity 112 in the core of the electrode assembly 110 is not blocked and remains open to the upper part (refer to the dashed circle).

[0416] When the cavity 112 is not blocked, there are no difficulties in the electrolyte injection process, thus improving the electrolyte injection efficiency. In addition, the welding process between the second current collector 145 and the battery canister 142 can be easily performed by inserting a welding fixture through the cavity 112.

[0417] When the uncoated portions 146a and 146b have a slitting structure, when the width and / or height and / or spacing of the cut pieces are adjusted in a manner that satisfies the numerical range of the above embodiments, the cut pieces are overlapped into multiple layers to a degree that sufficiently ensures the welding strength when bending the cut pieces, and no empty space (gap) is formed on the bending surface.

[0418] Regarding the structure of the uncoated portions 146a and 146b, it can be arbitrarily modified to the structure of the above embodiment (modified example) differently from the structure shown in the figure. In addition, a conventional uncoated portion structure can be applied to either side of the uncoated portions 146a and 146b.

[0419] Figure 23 This is a cross-sectional view of a cylindrical battery cell 200 according to another embodiment of the present invention, cut along the Y-axis.

[0420] Reference Figure 23 The cylindrical battery cell 200 includes Figure 14 The electrode assembly 110 shown, except for the electrode assembly 110 itself, has the same structure as... Figure 21 The cylindrical battery cell 180 shown is essentially the same.

[0421] Reference Figure 23 The uncoated portions 146a and 146b of the electrode assembly 110 are bent from the outer periphery towards the core. At this time, the height of the uncoated portion B1 on the core side is lower than that of the other portions, so it is not substantially bent. The first current collector 144 is welded to the bent surface of the uncoated portion 146a, and the second current collector 176 is welded to the bent surface of the uncoated portion 146b.

[0422] The height of the uncoated portion B1 on the core side of the electrode assembly 110 is relatively lower than that of other portions. Additionally, as... Figure 14 As shown, the height H of the innermost uncoated portion in the middle uncoated portion B2 is less than or equal to the radial length R of the core-side uncoated portion B1. Here, the height of the uncoated portion refers to the length from the reference line DL to the first side portion or the height of the slice.

[0423] Therefore, even if the uncoated portions 146a and 146b are bent toward the core, the cavity 112 in the core of the electrode assembly 110 is not blocked and remains open to the upper part (refer to the dashed circle).

[0424] When the cavity 112 is not blocked, there are no difficulties in the electrolyte injection process, thus improving the electrolyte injection efficiency. In addition, the welding process between the second current collector 176 and the battery canister 171 can be easily performed by inserting a welding fixture through the cavity 112.

[0425] When the uncoated portions 146a and 146b have a slitting structure, when the width and / or height and / or spacing of the cut pieces are adjusted in a manner that satisfies the numerical range of the above embodiments, the cut pieces are overlapped into multiple layers to a degree that sufficiently ensures the welding strength when bending the cut pieces, and no empty space (gap) is formed on the bending surface.

[0426] Regarding the structure of the uncoated portions 146a and 146b, unlike the structure shown in the figure, they can be arbitrarily modified to the structure of the above embodiment (modified example). Furthermore, a conventional uncoated portion structure can be applied to either side of the uncoated portions 146a and 146b.

[0427] Figure 24 This is a cross-sectional view of the cylindrical battery cell 210 of another embodiment of the present invention, cut along the Y-axis.

[0428] Reference Figure 24 The cylindrical battery cell 210 includes Figure 13 The electrode assembly 100 shown, except for the electrode assembly 100 itself, has the same structure as... Figure 17 The cylindrical battery cell 140 shown is essentially the same.

[0429] Preferably, the uncoated portions 146a and 146b of the electrode assembly A3 are bent from the outer periphery to the core. In this case, the core-side uncoated portion B1 and the outer periphery-side uncoated portion B3 of the uncoated portion 146a are lower in height than the other portions, and therefore are not substantially bent. The same applies to the uncoated portion 146b. A first current collector 144 is welded to the bent surface of the uncoated portion 146a, and a second current collector 145 is welded to the bent surface of the uncoated portion 146b.

[0430] The height of the uncoated core portion B1 is relatively lower than that of the uncoated middle portion B2. Additionally, as... Figure 14 As shown, the height H of the innermost uncoated portion in the middle uncoated portion B2 is less than or equal to the radial length R of the core-side uncoated portion B1. Here, the height of the uncoated portion refers to the length from the baseline DL to the first side portion or the height of the section.

[0431] Therefore, even if the uncoated portions 146a and 146b are bent toward the core, the cavity 102 in the core of the electrode assembly 100 is not blocked and remains open to the upper part (refer to the dashed circle).

[0432] When the cavity 102 is not blocked, there are no difficulties in the electrolyte injection process, thus improving the electrolyte injection efficiency. In addition, the welding process between the second current collector 145 and the battery canister 142 can be easily performed by inserting a welding fixture through the cavity.

[0433] Furthermore, the height of the uncoated portion B3 on the outer periphery is relatively lower than that of the uncoated portion B2 in the middle. Therefore, the uncoated portion B3 on the outer periphery does not actually bend when the uncoated portion 146a is bent. In addition, the uncoated portion B3 on the outer periphery is sufficiently separated from the rolled edge portion 147, thus solving the problem of damage to the uncoated portion B3 on the outer periphery during the pressing of the rolled edge portion 147.

[0434] When the uncoated portions 146a and 146b have a slitting structure, and the width and / or height and / or spacing of the lower cut pieces are adjusted in a manner that satisfies the numerical range of the above embodiments, the cut pieces are overlapped into multiple layers to a degree that sufficiently ensures the welding strength when bending the cut pieces, and no empty space (gap) is formed on the bending surface.

[0435] Regarding the structure of the uncoated portions 146a and 146b, it can be arbitrarily modified to the structure of the above embodiment (modified example) different from the structure shown in the figure. In addition, conventional uncoated portion structures can be applied to either of the uncoated portions 146a and 146b.

[0436] Figure 25 This is a cross-sectional view of a cylindrical battery cell 220 of another embodiment of the present invention, cut along the Y-axis.

[0437] Reference Figure 25 The cylindrical battery cell 220 includes Figure 13 The electrode assembly 100 shown, except for the electrode assembly 100 itself, has the same structure as... Figure 21 The cylindrical battery cell 180 shown is essentially the same.

[0438] Preferably, the uncoated portions 146a and 146b of the electrode assembly 100 are bent from the outer periphery towards the core. In this case, the height of the uncoated portion B1 on the core side of the uncoated portion 146a is lower than that of the other portions, so it is not substantially bent. The same applies to the uncoated portion 146b. The first current collector 144 is welded to the bent surface of the uncoated portion 146a, and the second current collector 176 is welded to the bent surface of the uncoated portion 146b.

[0439] The height of the uncoated portion B1 on the core side of the electrode assembly 100 is relatively lower than that of the uncoated portion B2 in the middle. Additionally, as... Figure 14As shown, the height H of the innermost uncoated portion in the middle uncoated portion B2 is less than or equal to the radial length R of the core-side uncoated portion B1. Here, the height of the uncoated portion refers to the length from the baseline DL to the first side portion or the height of the section.

[0440] Therefore, even if the uncoated portion 146a is bent toward the core, the cavity 102 in the core of the electrode assembly 100 is not blocked and remains open to the upper part (refer to the dashed circle).

[0441] When the cavity 102 is not blocked, there are no difficulties in the electrolyte injection process, thus improving the electrolyte injection efficiency. In addition, the welding process between the second current collector 176 and the battery canister 171 can be easily performed by inserting a welding fixture through the cavity 102.

[0442] Furthermore, the height of the outer peripheral uncoated portion B3 of the uncoated portion 146a is relatively lower than that of the middle uncoated portion B2. Therefore, when the uncoated portion 146a is bent, the outer peripheral uncoated portion B3 does not actually bend. The same applies to the uncoated portion 146b.

[0443] When the uncoated portions 146a and 146b have a slitting structure, when the width and / or height and / or spacing of the cut pieces are adjusted in a manner that satisfies the numerical range of the above embodiments, the cut pieces are overlapped in multiple layers to a degree that sufficiently ensures the welding strength when bending the cut pieces, and no empty space (gap) is formed on the bending surface.

[0444] Regarding the structure of the uncoated portions 146a and 146b, they can be arbitrarily modified to the structure of the above embodiment (modified example), differing from the structure shown in the figure. Furthermore, conventional uncoated portion structures can be applied to either of the uncoated portions 146a and 146b.

[0445] The cylindrical battery cell of the above embodiment (modified example) is used to manufacture battery packs.

[0446] Figure 26 This is a diagram that schematically illustrates the structure of a battery pack according to an embodiment of the present invention.

[0447] Reference Figure 26 The battery pack 300 of this embodiment includes an assembly electrically connected to a cylindrical battery cell 301 and a housing 302 for housing the assembly. The cylindrical battery cell 301 is one of the battery cells in the above embodiment (modification). In the accompanying drawings, for ease of illustration, components such as busbars, cooling units, and external terminals used for electrically connecting the cylindrical battery cells 301 are omitted from the drawings.

[0448] The battery pack 300 can be installed in a car. For example, a car can be an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. Cars can be four-wheeled or two-wheeled.

[0449] Figure 27 This includes Figure 26 The diagram illustrates the 300 battery pack for a car.

[0450] Reference Figure 27 An embodiment of the present invention, a vehicle V, includes a battery pack 300 according to an embodiment of the present invention. The vehicle V receives power from the battery pack 300 according to an embodiment of the present invention to operate.

[0451] According to another aspect of the invention, the uncoated portions protruding from the upper and lower parts of the electrode assembly are themselves used as electrode tabs, thereby reducing the internal resistance of the cylindrical battery cell and increasing the energy density.

[0452] According to another aspect of the invention, the structure of the uncoated portion of the electrode assembly is improved to prevent interference between the inner circumferential surface of the electrode assembly and the battery can during the formation of the rolled edge portion of the battery can, thereby preventing short circuits inside the cylindrical battery cell caused by partial deformation of the electrode assembly.

[0453] According to another aspect of the invention, the structure of the uncoated portion of the electrode assembly is improved to prevent the uncoated portion around the groove from being torn when the uncoated portion is bent, thereby significantly increasing the number of overlapping layers of the uncoated portion and improving the welding strength.

[0454] According to another aspect of the invention, the structure of the uncoated portion adjacent to the core of the electrode assembly is improved to prevent the voids in the core of the electrode assembly from being blocked when the uncoated portion is bent, thus facilitating the electrolyte injection process and the welding process of the battery can and current collector.

[0455] According to another aspect of the present invention, it is possible to provide a cylindrical battery cell with a structure that has low internal resistance, prevents internal short circuits, and improves the welding strength of the current collector and the uncoated portion, as well as a battery pack and an automobile thereof.

[0456] As described above, although the present invention has been illustrated by way of specific embodiments and accompanying drawings, the present invention is not limited thereto. Those skilled in the art can make various modifications and variations within the equivalent scope of the technical concept of the present invention and the claims set forth below.

[0457] Example

[0458] (1) Preparation of the current collector

[0459] 1) Preparation of the anode current collector

[0460] As shown in Table 1 below, a metal thin film (15 μm thick) of aluminum material current collector was prepared, including the uncoated portion of the sections to be formed in Group 1 and Group 2.

[0461] The aforementioned metal film has a length of (B1+B2+B3)4,000 mm along the winding direction from the core to the outer periphery, and a width of 75 mm along the winding axis. The metal film is divided into the following regions: B1 is the uncoated portion on the core side, B3 is the uncoated portion on the outer periphery side, and B2 is the uncoated portion in the middle between the core side and the outer side. The lengths of B1, B2, and B3 are 350 mm, 3500 mm, and 150 mm, respectively.

[0462] The specified width from the second side to the inward side in the width direction of the aforementioned metal film is the anode active material portion, and the remainder is the uncoated portion, i.e., the first part. Compared with the middle uncoated portion, the uncoated portion on the core side and the uncoated portion on the outer periphery side have a smaller height in the winding axis direction.

[0463] 2) Preparation of the cathode current collector

[0464] Except for the case where a copper thin film (10 μm thick) is used as the current collector material and the width formed along the winding axis is 80 mm, the cathode current collector is prepared in the same manner as the anode current collector.

[0465] Table 1

[0466]

[0467] (2) Cathode manufacturing

[0468] Average particle size D 50 A slurry for the cathode active material layer was prepared by mixing 11μm earthy natural graphite, carbon black, carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBR) with water at a weight ratio of 94:1.5:2:2.5, with the remaining components (excluding water) having a concentration of 50wt%. Next, the slurry was applied to the cathode active material portion of the current collector surface of a prepared copper material using a slot coating method at an injection rate of 40 m / min. The width of the cathode active material portion was 70 mm, and the width of the uncoated portion was 10 mm, based on the take-up axis direction. The loading amount of the cathode active material was 16 mg / cm², based on the electrode area. 2 The amount of the active material layer coated with the above cathode was dried in a 60m long hot air furnace while the furnace temperature was maintained at 130°C. Then, a cathode with a density of 3.45 g / cc was obtained by rolling and pressing to achieve a target thickness of 180 μm.

[0469] Next, the uncoated intermediate section is grooved using a laser and divided into multiple segments according to the conditions in Table 1 below. At this point, the lower ends of the grooves in each segment have substantially the same height.

[0470] (3) Anode manufacturing

[0471] Li(Ni) will be used as the anode active material 0.6 Mn 0.2 Co 0.2 O2 (NCM-622), carbon black as a conductive material, and polyvinylidene fluoride (PVdF) as a binder were added to water, which served as a dispersion medium, in a weight ratio of 96:2:2 to prepare an anode active material slurry. The slurry was coated onto the surface of the prepared aluminum current collector, and the anode was manufactured by drying and calendering under the same conditions as the cathode. In the anode, with the winding axis as the reference, the width of the anode active material portion was 65 mm, and the width of the uncoated portion was 10 mm.

[0472] At this point, regarding the anode active material layer, considering the theoretical discharge capacity of NMC622 mentioned above, the NP ratio of the battery is adjusted to 1.18 (118%, approximately 27.7 cm). 2 ).

[0473] Next, the aforementioned uncoated intermediate section is grooved using a laser and divided into multiple segments according to the conditions described in Table 1 below. At this point, the lower ends of the grooves in each segment have substantially the same height.

[0474] (4) Separation membrane manufacturing

[0475] Approximately 5% by weight of polyvinylidene fluoride copolymer (PVdF-HFP) polymer was added to tetrahydrofuran (THF) and dissolved at 50°C for at least 12 hours to prepare a polymer solution. 20% by weight of BaTiO3 powder with a particle size of approximately 400 nm was added to this polymer solution and dispersed to prepare a mixed solution (BaTiO3 / PVdF-HFP = 80:20 weight ratio). The mixed solution, prepared using a doctor blade method, was coated onto both sides of a polypropylene substrate. After coating, the THF was dried, resulting in an organic / inorganic composite porous separation membrane. The final membrane thickness was approximately 30 μm. Measurements using a porosimeter showed that the pore size and porosity of the final organic / inorganic composite porous separation membrane were 0.4 μm and 60%, respectively.

[0476] (5) Electrode assembly preparation

[0477] After the above preparations were performed, a gel roll-type electrode assembly was manufactured by stacking and winding the cathode / separation membrane / anode in that order. In Example 1, the end of the separation membrane in the width direction was positioned on the outside of the electrode assembly with reference to the above-mentioned baseline and at 30% (1.5 mm) of the height of the minimum bending section (group 1).

[0478] In Example 2, the end of the separation membrane in the width direction is positioned relative to the reference line and 10% (0.5 mm) of the height of the minimum bending section (group 1) is located in the direction outside the electrode assembly.

[0479] In the comparative example, the end of the separation membrane in the width direction is positioned relative to the aforementioned reference line and 50% of the height of the aforementioned minimum bending section (group 1) is located in the direction outside the aforementioned electrode assembly.

[0480] (6) Battery manufacturing (4680 type)

[0481] In Example 1, the exposed segments of groups 1 to 7 in the upper and lower parts of the electrode assembly were bent towards the core side. Then, an anode current collector and a cathode current collector were welded to the upper and lower bending surfaces, respectively. Then, a [fabrication system / process] was manufactured. Figure 25 The structure shown is a cylindrical unit. Specifically, an electrode assembly with welded anode and cathode current collectors is inserted into a battery casing pre-installed with external terminals. The anode current collector and external terminals are welded together, and the edge of the cathode current collector is welded to the rolled edge. The battery casing is then introduced into the cavity of the electrolyte injection device, with the opening of the battery casing facing the opposite direction to gravity, thus uprighting the battery casing. Next, a non-aqueous electrolyte is prepared by dissolving LiPF6 in an organic solvent containing ethylene carbonate (EC), dimethyl carbonate (DMC), and diethyl carbonate (DEC) in a 1:2:1 (volume ratio) concentration to achieve a concentration of 1.0 M. Then, after injecting the electrolyte through the opening of the battery casing, the pressure in the cavity is increased to 800 kPa over 20 seconds and maintained for 150 seconds, followed by a 20-second reduction in pressure to -90 kPa and maintenance for 20 seconds to achieve a substantial vacuum state. After the electrolyte impregnation process is completed, the open part of the battery casing is sealed by a gasket to complete the fabrication of the cylindrical unit.

[0482] The batteries of Example 2 and Comparative Example 1 were also manufactured using substantially the same manufacturing process as described above.

[0483] (7) Evaluation of electrolyte impregnation amount

[0484] The batteries of Example 1, Example 2, and Comparative Example 1 were disassembled to obtain the anode and cathode, respectively. Then, 10cm sections were cut from the cathode and anode at a total of 9 locations.2 Nine samples were taken as follows: three samples (#1 to #3) were taken from the region adjacent to the core of the electrode assembly when the electrode was unfolded; three samples (#7 to #9) were taken from the region adjacent to the outer periphery of the electrode assembly; three samples (#4 to #6) were taken from the central region of the electrode relative to the winding direction; and when taking three samples from each sample area, one sample was taken from the lower end, center, and upper end of the active material layer along the winding axis. Furthermore, #1, #4, and #7 represent the area near one end in the electrode width direction; #3, #6, and #9 represent the area near the other end in the electrode width direction; and #2, #5, and #8 represent the middle portion. Figure 34 Please refer to the sample collection section. However, Figure 34 Based on Figure 7a Only the sample portion is shown; the appearance or values ​​of the sample portion are shown in Table 1 above.

[0485] The amount of electrolyte impregnation depends on the type of control sample and the weight difference of the sample taken. The control sample was manufactured with the same electrodes as those used in Examples 1, 2, and 1 (Comparative Example 1), and the same sampling locations were obtained for the anode and cathode that were never impregnated with electrolyte.

[0486] In the electrode assembly of Example 1, the average electrolyte impregnation amount for each part #1 to #9 was 60.3 mg, in Example 2 it was 59.6 mg, and in Comparative Example 1 it was 56.3 mg. The electrolyte impregnation amount in Examples 1 and 2 was higher than that in Comparative Example 1.

[0487] Furthermore, the total amount of electrolyte impregnation of the anode and cathode samples taken from the central position (#2) of the active material portion in the sample collection area adjacent to the core of the electrode assembly, based on the winding axis direction, is 55.1 mg in the case of the electrode assembly of Example 1, 59 mg in the case of the electrode assembly of Example 2, and 47.7 mg in the case of the electrode assembly of Comparative Example 1. This indicates that even with a relatively low electrolyte impregnation around the core of the electrode assembly, Examples 1 and 2 still have a higher amount than Comparative Example 1.

[0488] Table 2

[0489]

Claims

1. An electrode assembly comprising a first electrode plate, a second electrode plate, and a separation membrane sandwiched therebetween. The aforementioned first electrode plate, second electrode plate, and separation membrane are wound in one direction around an axis, forming multiple winding loops. The electrode assembly is characterized by the following features: The first electrode plate and the second electrode plate each independently include a first side portion and a second side portion, which are arranged on opposite sides of each other in the axial direction. The first electrode plate and the second electrode plate each independently include a first portion and a second portion on at least one surface. The first portion is an electrode active material portion coated with electrode active material and extends from the second side portion toward the first side portion. The second part described above is the uncoated portion without electrode active material, and extends from the first side portion toward the second side portion to the electrode active material portion of the first part. At least a portion of the aforementioned uncoated portion is divided into multiple segments by a cut groove of a specified depth. The aforementioned section has a first end portion that is consistent with the first side portion. All or at least a portion of the aforementioned segment is bent radially relative to the axis at the bending point, which is any location within the segment below the first end. The end of the separation membrane on either side is located between the bending position of each of the aforementioned segments and the boundary line of the first and second portions. in, The end of either side of the aforementioned separation membrane is located between the aforementioned bend position and the baseline or below the baseline, which is a straight line extending in the winding direction (X) at a height corresponding to the grooves of the slits that divide the multiple sections. The bent section among the above-mentioned sections is referred to as the bent section. Relative to the smallest bent section with the smallest height among the above-mentioned bent sections, the end of the separation membrane in the width direction is positioned on the outer side of the electrode assembly with reference to the baseline and less than 50% of the height of the smallest bent section, or the end of the separation membrane in the width direction is positioned on the inner side of the electrode assembly with reference to the baseline and within 30% of the height of the smallest bent section.

2. The electrode assembly according to claim 1, characterized in that, The end of either side of the separation membrane is located between the bending position and the boundary line of the first and second parts, and the separation membrane is configured in a manner that does not expose the groove of the cut groove.

3. The electrode assembly according to claim 1, characterized in that, The aforementioned bending position is any position between the first end and the baseline.

4. The electrode assembly according to claim 3, characterized in that, The cut pieces of the first electrode plate and the second electrode plate are each at a different distance from the reference line to the first end along the winding direction.

5. The electrode assembly according to claim 3 or 4, characterized in that, In the aforementioned bent sections, adjacent winding sections continuously overlap in the radial direction or opposite direction, forming a surface area at the upper or lower end of the winding axis of the electrode assembly. Let the shortest distance between the highest point in the aforementioned surface region and the aforementioned baseline be the height (Has) of the surface region. The end of either side of the separation membrane is positioned relative to the reference line and within 90% of the height (Has) of the surface area in the first side direction of the electrode assembly or in the second side direction of the electrode assembly below the reference line.

6. The electrode assembly according to claim 1, characterized in that, The aforementioned uncoated portion includes a core-side uncoated portion adjacent to the core of the electrode assembly, an outer peripheral-side uncoated portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate uncoated portion sandwiched between the core-side uncoated portion and the outer peripheral-side uncoated portion. At least one of the aforementioned uncoated core portion and the aforementioned uncoated outer peripheral portion has a relatively smaller distance from the reference line and the first side portion compared to the aforementioned uncoated intermediate portion.

7. The electrode assembly according to claim 6, characterized in that, The distance from the core uncoated portion to the baseline and the first side portion is relatively smaller compared to the middle uncoated portion and the outer peripheral uncoated portion.

8. The electrode assembly according to claim 7, characterized in that, The height of the uncoated portion on the core side is consistent with the baseline.

9. The electrode assembly according to claim 8, characterized in that, The aforementioned uncoated portion on the core side includes the uncoated portion of the electrode plate corresponding to the innermost winding of the electrode assembly. The aforementioned uncoated portion on the outer periphery includes the uncoated portion of the electrode plate portion corresponding to the outermost winding of the electrode assembly.

10. The electrode assembly according to claim 9, characterized in that, The aforementioned uncoated portion is divided into multiple sections, including all or at least a portion thereof.

11. The electrode assembly according to claim 10, characterized in that, The aforementioned bending point is at least 0.1 mm away from the aforementioned separation membrane.

12. The electrode assembly according to claim 1, characterized in that, The distance from the first end of the aforementioned minimum bending section to the baseline is 2 mm or more.

13. The electrode assembly according to claim 12, characterized in that, The electrode assembly described above also includes a segment with a height smaller than the minimum bending segment, i.e., segment A, or does not include a segment with a height smaller than the minimum bending segment, where the minimum bending segment is the minimum segment. The height of the segment refers to the shortest distance from the baseline to the first end of the segment.

14. The electrode assembly according to claim 6, characterized in that, At least a portion of the aforementioned uncoated intermediate portion increases in height in stages along the winding axis as it moves from the core side toward the outer periphery side.

15. The electrode assembly according to claim 13, characterized in that, At least one of the height in the winding axis direction and the width in the winding direction of the aforementioned plurality of sections increases individually or in each group, as it moves from the core side toward the outer periphery side.

16. The electrode assembly according to claim 15, characterized in that, The aforementioned multiple sections respectively satisfy at least one of the following conditions: a width condition of 1 mm to 6 mm in the winding direction; a height condition of 2 mm to 10 mm in the winding shaft direction; and a spacing condition of 0.05 mm to 1 mm in the winding direction.

17. The electrode assembly according to claim 16, characterized in that, The aforementioned multiple segments satisfy a spacing condition of 0.05 mm to 1 mm in the winding direction. The spacing is specified according to the distance between the corners of two adjacent segments, and a chamfered reinforcement is added to the corner of the adjacent segments.

18. The electrode assembly according to claim 17, characterized in that, The above separation membrane includes: Porous polymer substrates; and A porous coating is located on at least one side of the aforementioned porous polymer substrate and comprises inorganic particles and adhesive polymers.

19. The electrode assembly according to claim 18, characterized in that, The aforementioned inorganic particles include inorganic particles with hydrophilic properties on their surface.

20. A cylindrical battery cell, characterized in that, include: The electrode assembly according to any one of claims 1 to 19; A battery can housing the aforementioned electrode assembly, which is electrically connected to one of the aforementioned first electrode plate and the aforementioned second electrode plate and has a first polarity; A sealing body that seals the open end of the aforementioned battery can; and A terminal, which is electrically connected to another of the first electrode plate and the second electrode plate, has its surface exposed to the outside and has a second polarity. The above separation membrane has the following features: Porous polymer substrates; and A porous coating is located on both sides of the aforementioned porous polymer substrate and includes inorganic particles and adhesive polymers.

21. A battery pack, characterized in that, It includes at least one battery cell according to claim 20.

22. A car, characterized in that, It includes at least one battery pack as claimed in claim 21.

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