Electrode assembly, battery, battery pack and vehicle

Abstract

Electrode assembly (A; 80) comprising a positive electrode (10), a negative electrode (11) and a separator (12) arranged therebetween, wherein the positive electrode (10), the negative electrode (11) and the separator (12) are wound around a winding axis (Y), wherein the negative electrode (11) has a negative active material portion coated with a negative active material and an uncoated portion (43) which is free of the negative active material, wherein the uncoated portion is located at an edge of the negative electrode (11) extending along a winding direction (X), wherein the uncoated portion (43) is designed to provide an electrical connection to the negative electrode (11), wherein the uncoated portion comprises a plurality of separate tabs (61) which are individually bendable in a radial direction, wherein a height of an outermost region having an outermost winding turn of the uncoated portion is smaller than heights of the plurality of separate tabs (61), wherein the plurality of separate tabs (61) are bent in the direction of the winding axis (Y) to form a bending surface area (F), wherein the bending surface region (F) comprises a region with a uniform number of overlap layers (b1), in which the number of overlapping layers of the separate tabs (61) is uniform, and a region with a decreasing number of overlap layers (b2) located adjacent to the region with a uniform number of overlap layers (b1), in which the number of overlapping layers of the separate tabs (61) decreases in a direction away from the region with a uniform number of overlap layers (b1), and wherein a combined thickness of the overlapping layers of the separate tabs (61) in the region with a uniform number of overlapping layers (b1) is between 50 µm and 700 µm.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to an electrode assembly, a battery and a battery pack, and a vehicle incorporating the same. STATE OF THE ART

[0002] Secondary batteries, which are easily applicable to various product groups and have electrical properties such as high energy density, are universally used not only for portable devices but also for electric vehicles (EVs) or hybrid electric vehicles (HEVs) powered by an electric power source.

[0003] These secondary batteries are attracting attention as a new energy source to improve environmental friendliness and energy efficiency because they have the primary advantage of drastically reducing the use of fossil fuels and the secondary advantage of not producing any by-products from the use of energy.

[0004] Secondary batteries currently widely used in technology include lithium-ion batteries, lithium polymer batteries, nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, and the like. A secondary battery unit, namely a unit battery, has an operating voltage of approximately 2.5V to 4.5V. Therefore, when a higher output voltage is required, a battery pack can be constructed by connecting multiple batteries in series. In addition, multiple batteries can be connected in parallel to form a battery pack according to the charge / discharge capacity required for the battery pack. Accordingly, the number of batteries included in the battery pack and the form of electrical connection can be varied according to the required output voltage and / or charge / discharge capacity.

[0005] Meanwhile, cylindrical, rectangular, and pouch-shaped batteries are known as types of secondary battery units. In the case of a cylindrical battery, a separator serving as an insulator is interposed between a positive electrode and a negative electrode, and they are wound to form an electrode assembly in a jelly-roll structure, which is inserted into a battery case to form a battery. In addition, a strip-shaped electrode tab may be connected to an uncoated portion of each of the positive electrode and the negative electrode, and the electrode tab electrically connects the electrode assembly and an electrode terminal exposed to the outside. For example, let the positive electrode terminal be a cap of a sealing body that seals the opening of the battery case, and the negative electrode terminal is the battery case.However, according to the conventional cylindrical battery having such a structure, the current collection efficiency is not good due to the large resistance and large heat generation because current is concentrated in the strip-shaped electrode tab coupled to the uncoated portion of the positive electrode and / or the uncoated portion of the negative electrode.

[0006] For small cylindrical batteries with a form factor of 1865 (diameter: 18 mm, height: 65 mm) or 2170 (diameter: 21 mm, height: 70 mm), resistance and heat are not a major problem. However, when the form factor is increased for use in electric vehicles, the cylindrical battery can ignite if excessive heat is generated around the electrode tab during a fast-charging process.

[0007] To solve this problem, a cylindrical battery (so-called tabless cylindrical battery) is provided in which the uncoated portion of the positive electrode and the uncoated portion of the negative electrode are designed to be positioned at the top and bottom of the jelly-roll electrode assembly, respectively, and the current collector is welded to the uncoated portion to improve the current collection efficiency. DESCRIPTION

[0008] Fig. 1 to Fig. 3 are diagrams showing a manufacturing process of a tabless cylindrical battery. Fig. 1 shows the structure of an electrode, Fig. 2 shows a winding process of the electrode and Fig. 3 shows a welding process of a current collector to a bent surface area of ​​an uncoated section.

[0009] With reference to Fig. 1 to Fig. 3, a positive electrode 10 and a negative electrode 11 have a structure in which a plate-shaped current collector 20 is coated with an active material 21, and have an uncoated portion 22 on a long side along the winding direction X. The long side is a direction parallel to the x-axis direction, which means a side with a relatively long length.

[0010] An electrode assembly A is manufactured by stacking the positive electrode 10 and the negative electrode 11 sequentially together with two plates of separators 12 as shown in Fig. 2, and then wound in a direction X. Meanwhile, the uncoated portions of the positive electrode 10 and the negative electrode 11 are oriented in opposite directions.

[0011] After the winding process, the uncoated portion 10a of the positive electrode 10 and the uncoated portion 11a of the negative electrode 11 are bent toward the core. Current collectors 30, 31 are then welded and coupled to the uncoated portions 10a and 11a, respectively.

[0012] An electrode tab is not separately coupled to the uncoated portion 10a of the positive electrode and the uncoated portion 11a of the negative electrode. The current collectors 30, 31 are connected to external electrode terminals, and a current path with a large cross-sectional area is formed along the winding axis direction of the electrode assembly A (see arrow), which has the advantage of reducing the battery's resistance. This is because the resistance is inversely proportional to the cross-sectional area of ​​the path through which the current flows.

[0013] In the tabless cylindrical battery, in order to improve the welding properties of the uncoated sections 10a, 11a and the current collectors 30, 31, strong pressure must be applied to the welding area of ​​the uncoated sections 10a, 11a to bend the uncoated sections 10a, 11a as flat as possible.

[0014] However, if the welding area of ​​the uncoated portions 10a, 11a is bent, the shapes of the uncoated portions 10a, 11a may be irregularly distorted and deformed. In this case, the deformed portion may come into contact with the electrode of opposite polarity to cause an internal short circuit or induce microcracks in the uncoated portions 10a, 11a. In addition, since the uncoated portion 32 adjacent to the core of the electrode assembly A is bent, all or a significant portion of the cavity 33 in the core of the electrode assembly A is blocked. In this case, it causes a problem in the electrolyte injection process. That is, the cavity 33 in the core of the electrode assembly A is used as a passage through which an electrolyte is injected. However, if the corresponding passage is blocked, electrolyte injection is difficult.In addition, while an electrolyte injector is inserted into the cavity 33, the electrolyte injector may disturb the uncoated portion 32 near the core, which may cause the uncoated portion 32 to crack.

[0015] In addition, the bent portions of the uncoated sections 10a, 11a to which the current collectors 30, 31 are welded should be overlapped in multiple layers, and there should be no empty spaces (gaps). In this way, sufficient weld strength can be obtained, and even with the latest technology, such as laser welding, laser penetration into the electrode assembly A and melting the separator or active material can be prevented.

[0016] Meanwhile, in the conventional tabless cylindrical battery, the uncoated portion 10a of the positive electrode is completely formed on the upper portion of the electrode assembly A. Therefore, when the outer periphery of the top surface of the battery case is pressed inward to form a bead portion, an upper edge portion 34 of the electrode assembly A is compressed by the battery case. This compression may cause partial deformation of the electrode assembly A, which may rupture the separator 12 and cause an internal short circuit. If a short circuit occurs inside the battery, it may cause the battery to overheat or explode. TECHNICAL TASK

[0017] The present disclosure is designed to solve the problems of the prior art, and therefore, the present description is directed to providing an electrode assembly having an improved structure of the uncoated portion to relieve stresses exerted on the uncoated portion when bending the uncoated portion exposed at both ends of the electrode assembly.

[0018] The present disclosure is also directed to providing an electrode assembly in which an electrolyte injection passage is not blocked even if the uncoated portion is bent.

[0019] The present disclosure is also directed to providing an electrode assembly including a structure capable of preventing a top edge of the electrode assembly from contacting an inner surface of a battery case when the top of the battery case is crimped.

[0020] The present disclosure is also directed to providing an electrode assembly that improves the physical properties of a weld area by applying a segment structure to the uncoated portion of the electrode and by optimizing the dimensions (width, height, separation pitch) of the segments to sufficiently increase the number of overlapping layers of the segments in an area used as a predetermined weld area.

[0021] The present disclosure is also directed to providing an electrode assembly with improved energy density and reduced resistance by applying a structure in which a current collector is welded over a large area to a bending surface region formed by bending the segments.

[0022] The present disclosure is also directed to providing a battery including a terminal and a current collector with an improved design for performing electrical wiring at an upper portion thereof.

[0023] The present disclosure is also directed to providing a battery including the electrode assembly with an improved structure, a battery pack including the battery, and a vehicle including the battery pack.

[0024] The technical problems to be solved by the present disclosure are not limited to the above, and other problems not mentioned here will be clearly understood by those skilled in the art from the following disclosure. TECHNICAL SOLUTION

[0025] The present invention is defined by the subject matter of the independent claims. Particular examples of the present invention are defined by the features of the dependent claims. Furthermore, any of the features described above may also be incorporated into the claimed subject matter, unless this is inappropriate.

[0026] An electrode assembly may include a first electrode, a second electrode, and a separator. The separator may be disposed between the first and second electrodes. The first electrode, the second electrode, and the separator may be wound around a winding axis. The first electrode may include a first active material portion and a first uncoated portion. The first active material layer may be coated with an active material (active material layer). The first uncoated portion may be free of the active material layer. The first uncoated portion may be (formed, arranged, disposed) at an edge of the first electrode, wherein the edge extends along a winding direction of the electrode assembly. The first uncoated portion may be configured to provide an electrical connection to the first electrode.The first uncoated portion may include a first portion, a second portion, and a third portion. The third portion may be disposed between the first and second portions. A height of the first portion and / or a height of the second portion may be smaller than a height of the third portion. The heights may be determined in a winding axis direction parallel to the winding axis (winding axis) of the electrode assembly. The height of the first uncoated portion may be determined as its size in the winding direction from the boundary of the active material portion or from a region where the (first) active material is deposited.

[0027] The electrode assembly may have a (generally approximately substantially) cylindrical shape and, accordingly, a cylindrical geometry. The outer periphery of the wound first and second electrodes and the separator disposed therebetween may have a generally cylindrical shape. The cylindrical geometry may define an axial direction, a radial direction, and a circumferential direction (tangential direction) according to basic mathematics. The winding axis of the electrode assembly may be parallel to the axial direction. The axial direction may correspond to the winding axis direction of the electrode assembly. The winding direction may be perpendicular to the winding axis direction. The winding direction may approximately correspond to the circumferential direction of the electrode assembly. Here, a height in the axial direction (i.e., the winding axis) may be determined unless otherwise stated.Here, a width can be specified in the winding or circumferential direction, unless otherwise specified.

[0028] The wound first and second electrodes and the separator disposed therebetween may have a cross-section corresponding to a spiral shape. A core may refer to a generally cylindrical cavity and may be referred to as a hollow core portion. The description "generally cylindrical," as used herein with reference to the wound first and second electrodes and the separator disposed therebetween, should be understood to refer to the inner and / or outer cylindrical surface, which may have a step-like transition at the terminal inner or outer winding edge, respectively, with respect to the penultimate winding. The terminal winding edge may extend (generally approximately) parallel to the winding axis. The terminal winding edge may alternatively be referred to as a short side end.The other side ends connecting between the short side ends may be referred to as long side ends. The edge extending in the winding direction and at which the uncoated portion is located may be a long side end of the first electrode.

[0029] In a rolled-out view (i.e., without winding or rolling) of the electrode assembly, each of the first electrode, the second electrode, and the separator may extend in the axial direction between two respective long side ends. Each of the first electrode, the second electrode, and the separator may extend in the winding direction between two respective short side ends. In some examples, each of the long side ends may be longer than each of the short side ends. The long side end of each of the first and second electrodes and the separator may correspond to a longer or longest side end of each of the plate-shaped first and second electrodes and the separator.For example, for a first electrode, a second electrode, or a separator that has a substantially rectangular shape before being rolled to form the electrode assembly of the battery, an edge of the rectangle formed by the unrolled separator that corresponds to the longer side of the rectangle may correspond to the respective "long side end." The long side end of each of the first and second electrodes and the separator may therefore be perpendicular to a height direction of the battery. In the direction perpendicular to the height of the battery, the first uncoated portion of the first electrode may protrude from and / or extend beyond the separator. Alternatively, the terms "long" and "short" may be nominal, and each of the short side ends may be longer than the long side ends. Each of the long side ends may be linear, curved, or patterned (e.g.,with segments as described below) or a combination thereof.

[0030] The first electrode may comprise a sheet, plate, or foil on which the active material is deposited. In general, the first electrode may be a positive electrode or a negative electrode. A region of the first electrode on which the active material is deposited (coated with the active material) may be referred to as the first active material portion. The first electrode may be coated with the active material except for the uncoated portion along the edge (which may be one of the long sides, as described above) of the first electrode. Here, an edge may refer to an end side, a terminal edge, or a boundary of the respective component.

[0031] The electrode assembly may include any of the features of an electrode assembly as disclosed herein. Each of the first electrode, the second electrode, and the separator may include any of the respective features as described below.

[0032] The first uncoated portion may be made of a conductive material to provide an electrical connection to the first electrode. The first uncoated portion may be a portion of a sheet, plate, or foil of the first electrode. The first uncoated portion may be dimensioned and arranged to provide an electrical connection to the first electrode. In particular, the first uncoated portion may be configured for electrical connection between a terminal and the first electrode. Thus, the first uncoated portion may function as a tab for the first electrode. Since the first uncoated portion is part of the first electrode, the first electrode itself may function as a tab.

[0033] The first portion, the second portion, and the third portion of the first uncoated portion may be arranged adjacent to each other in the winding direction. The first, second, and third portions may have different sizes (i.e., overall widths) in the winding direction. In the wound electrode assembly, the first uncoated portion or any of the first, second, and third portions may be bendable in the radial direction toward the winding axis (i.e., inward) or outward. Unless inappropriate or otherwise specified, terms such as "inside," "inward(outward)," "innermost" are used toward a volume center of the (wound) electrode assembly. Accordingly, terms such as "outside," "outward(outward)," "outermost" are used to indicate a direction or a direction away from the volume center of the (wound) electrode assembly.

[0034] In the wound electrode assembly, the first uncoated portion of the first electrode may initially protrude in the winding axis direction above and between end surfaces of the second electrode and the separator. The end surfaces may be collectively referred to as an end surface of the electrode assembly with reference to the cylindrical geometry. Accordingly, the wound electrode assembly may have two end surfaces and a lateral surface extending therebetween.

[0035] The first, second, and third sections of the first uncoated portion of the first electrode of the electrode assembly can be dimensioned and arranged, in particular with respect to their respective heights, to provide an optimized contact area with the first electrode. In particular, the uncoated portion can be used to provide a contact area for a current collector, as described below. The first uncoated portion can be utilized to increase the contact area compared to conventional arrangements, in particular for enlarged battery cell assemblies. The height of any or each of the first portion, second portion, and third portion can be determined as a respective dimension in the winding direction from the boundary of the active material portion or from a region in which the (first) active material is deposited.

[0036] In one aspect, an electrode assembly is provided in which a first electrode, a second electrode, and a separator disposed therebetween are wound based on a winding axis to define a core and an outer periphery, wherein the first electrode has a first active material portion coated with an active material layer and a first uncoated portion not coated with an active material layer along a winding direction, wherein at least a portion of the first uncoated portion is defined per se as an electrode tab, wherein the first uncoated portion has a first portion adjacent to the core of the electrode assembly, a second portion adjacent to the outer periphery of the electrode assembly, and a third portion disposed between the first portion and the second portion,and wherein the first section or the second section has a lower height in the winding axis direction than the third section.,

[0037] In one example, the second portion may be defined as the electrode tab in a state bent along the radial direction of the electrode assembly. Additionally or alternatively, the third portion may be defined as the electrode tab in a state bent along the radial direction of the electrode assembly. The third portion may be defined as the electrode tab in a state bent along a radial direction of the electrode assembly. In general, an electrode tab may refer to a structure that provides an electrical connection to a respective electrode, in particular for an external load or a terminal of a battery cell.

[0038] In another example, the second portion and the third portion may be defined as the electrode tab in a state bent along a radial direction of the electrode assembly.

[0039] For example, the third section may be at least partially formed into a plurality of separate tabs. The separate tabs may, for example, be bendable in the radial direction. Alternatively or additionally, at least a portion of the third section may be divided into a plurality of independently bendable segments. Here, the terms separate tab and segment may be used interchangeably. Furthermore, the separate tabs may also be referred to as foil tabs, tab fingers, various parts, separating parts, cut sections, or the like.

[0040] All or some of the separate tabs may have a polygonal shape, in particular a quadrangular shape with an inner side (i.e., a base) adjacent to a continuous (strip-shaped) part of the first uncoated portion. Each of the separate tabs may extend from the inner side in the axial direction (winding axis direction) to an outer side. All or some of the separate tabs may have a lateral side extending between the inner side and the outer side. The separate tabs may be provided sequentially along the edge of the first electrode at which the first uncoated portion is arranged. As indicated below, the separate tabs may have individually or in groups identical shapes and / or dimensions. The separate tabs may have any of the features described below.

[0041] For example, each of the plurality of separate tabs (segments) may have a geometric shape connecting one or more straight lines, one or more curves, or a combination thereof. For example, each of the separate tabs may have a non-polygonal shape, with at least one of the outer and lateral sides being non-straight. In general, any two-dimensional shape in a plan view may be considered for the separate tabs.

[0042] In one example, the third portion may be at least partially formed into a plurality of separate tabs that are individually bendable. All or some of the separate tabs may be configured to be bent. In particular, the separate tabs may be shaped (e.g., a single shape and / or according to a pattern) and / or dimensioned (e.g., with respect to heights, widths, thicknesses) such that they can be individually bent by applying an external force. Each, every, or all of the separate tabs may be bent in a state in which the electrode assembly is wound.

[0043] As stated above, the width in the winding direction may be fixed. In one example, the width of one or more or each of the plurality of separate tabs may decrease in the winding axis direction away from the active material layer. Alternatively, the width of one or more or each of the plurality of separate tabs may decrease in the winding axis direction away from the active material layer and then increase. Alternatively, the width of one or more or each of the plurality of separate tabs may increase in the winding axis direction away from the active material layer and then decrease. Alternatively, the width of one or more or each of the plurality of separate tabs may increase along the winding axis direction away from the active material layer and then remain constant. Alternatively, the width of one or more or each of the plurality of separate tabs may decrease along the winding axis direction away from the active material layer and then remain constant.Alternatively, the width of one or more or each of the plurality of separate tabs may remain unchanged along the winding axis direction.

[0044] In one example, in each of the plurality of segments, a width of a lower portion may be greater than a width of an upper portion.

[0045] In one example, in each of the plurality of segments, a width of a lower portion may be identical to a width of an upper portion.

[0046] In one example, each of the plurality of segments may have a width that gradually decreases from a lower portion to an upper portion.

[0047] In one example, each of the plurality of segments may have a width that gradually decreases and then increases from a lower portion to an upper portion.

[0048] In one example, each of the plurality of segments may have a width that gradually increases and then decreases from a lower portion to an upper portion.

[0049] In one example, each of the plurality of segments may have a width that gradually increases from a lower portion to an upper portion and is then kept constant.

[0050] In one example, each of the plurality of segments may have a width that gradually decreases from a lower portion to an upper portion and then is kept constant.

[0051] In one example, the width of at least one of the plurality of separate tabs in the winding axis direction may be smaller at an outermost location than at an innermost location. Alternatively, the width of at least one of the plurality of separate tabs in the winding axis direction may be equal to that at an innermost location. Thus, the width of any or all of the separate tabs may vary along the winding axis direction. This may be used to optimize a contact area, a tab arrangement, or the electrical connection.

[0052] For example, each of the plurality of segments may have a side formed with one or more straight lines, one or more curves, or a combination thereof.

[0053] In one example, each of the plurality of segments may have a side that is outwardly convex or inwardly convex.

[0054] In another example, a corner of a top portion of each of the plurality of segments may have a round shape.

[0055] In one example, the plurality of separate tabs may be shaped to form interior angles proximal to the active material layer that increase individually or in groups in the winding direction. The interior angles may be formed between the inner side and the lateral side of a particular separate tab in a view (in a thickness direction of the first electrode plate or in the radial direction of the wound electrode assembly). The interior angle may also be referred to below as a bottom angle. For example, the plurality of segments may have a bottom interior angle that increases individually or in groups in a direction parallel to the winding direction.

[0056] In one example, the (lower) interior angle of the plurality of segments may increase individually or in groups in a range of 60 to 85 degrees in a direction parallel to the winding direction. For example, the range may be 45 to 90 degrees, or 45 degrees or greater, 55 degrees or greater, 60 degrees or greater, 65 degrees or greater, or 70 degrees or greater, and 90 degrees or less, 85 degrees or less, 80 degrees or less, or 75 degrees or less.

[0057] In one example, the width of one or more or each of the plurality of separate tabs decreases in the winding axis direction away from the active material layer. A lower interior angle θ of a separate tab located at a position corresponding to a radial distance r from the winding axis of the electrode assembly satisfies the following formula. cos−1(0.5*Dr)≤θ≤tan−1(2*H*tanθrefer2*H−p*tanθrefer)

[0058] Here, D is a segment width of the segment in the winding direction; r is a radius of the winding turn containing the segment; H is a segment height of the segment; p is a separation distance (pitch) of the segment. Additionally or alternatively, each of the plurality of segments may have a geometric shape with a width that gradually decreases from a lower portion to an upper portion, and a lower interior angle (θ) of a segment located in a winding turn with a radius (r) based on the core of the electrode assembly may fall within an angular range of the above formula. The radial distance may be determined in the radial direction. The separation distance may imply a regular distance and refer to a distance between repeating positions of the separation tabs.

[0059] In one example, each of the plurality of segments has a side formed with one or more straight lines, one or more curves, or a combination thereof.

[0060] In one example, each of the plurality of segments has a side that is outwardly convex or inwardly convex. The side may refer to any of the outer sides and lateral sides described above.

[0061] In one example, one or more or each of the plurality of separate tabs may have a rounded corner on a respective outermost side. In other words, a corner of an upper portion of each of the plurality of segments has a rounded shape. The corner may be located between the outer side and one of the lateral sides of the respective separate tab.

[0062] For example, a cut groove may be formed between each of the separate tabs that are adjacent in the winding direction. Corners of the cut groove may be rounded. In other words, a cut groove may be arranged between segments that are adjacent to each other along the winding direction, and a lower portion of the cut groove may include a bottom portion and a round portion for connecting both ends of the bottom portion to sides of the segments on both sides of the cut groove. The cut groove may refer to a cavity that extends inward from the edge of the first electrode in the winding axis direction. Thus, a cut groove may separate two separate tabs that are adjacent along the winding direction. The cut groove may also be referred to as a notch or a recess or the like.

[0063] In one example, the corners of the cut groove may be rounded with a radius of curvature of 0 to 0.1 mm or 0.01 mm to 0.05 mm. In other words, the round portion may have a radius of curvature greater than 0 and less than or equal to 0.1 mm, more preferably 0.01 mm to 0.05 mm. The radius of curvature may be 0.02 to 0.04 mm.

[0064] In one example, the inner side (bottom portion) of the cut groove may be flat. Flat may refer to a substantially straight linear shape when viewed in the radial direction (or the thickness direction).

[0065] In one example, the plurality of separate tabs are spaced apart in the winding direction by a separation distance, which may be 0.05 to 1.00 mm. In other words, a separation distance, defined as an interval between two points where lines extending from the sides of two segments located on either side of the cut slot meet a line extending from the bottom portion of the cut slot, may be 0.05 mm to 1.00 mm.

[0066] In one example, the plurality of segments may be formed from aluminum foil. A separation distance, defined as the interval between two points where lines extending from the sides of two segments located on either side of the cut groove meet a line extending from the bottom portion of the cut groove, may be 0.5 mm to 1.00 mm.

[0067] In one example, an inner side of the cut groove may be spaced apart from the active material layer by a certain distance. In other words, the lower portion of the cut groove may be offset from the active material layer by a predetermined distance.

[0068] For example, the specific distance (a separation distance) between the lower portion of the cut groove and the active material layer may be 0.2 mm to 4 mm.

[0069] For example, one or more or each of the plurality of separate tabs may be bent at a location located on an inner side of the adjacent cut groove or offset outward from an inner side of the adjacent cut groove by 1 mm or less. In other words, a bending range of the plurality of segments in a radial direction of the electrode assembly is located in the range of 0 to 1 mm above a lower end of the cut groove.

[0070] In one example, one or more or each of the plurality of separate tabs may have a lateral side that defines the boundary of the respective separate tab in the winding direction. Optionally, the lateral side may be provided such that, after bending the respective separate tab, it forms a central angle of 45 degrees or less at the winding axis of the electrode assembly. In other words, in each of the plurality of segments, a circumferential angle of an arc formed by a lower end of the segment based on a core center of the electrode assembly may be 45 degrees or less. Further optionally, the lateral side may be provided such that, after bending the respective separate tab, it forms a constant central angle at the winding axis of the electrode assembly.

[0071] For example, for one or more or each of the plurality of separate tabs D(r), the following formula may be satisfied, where r is a distance of the respective separate tab from the winding axis of the electrode assembly in the radial direction and D(r) is a width of the respective separate tab in the winding direction. 1≤D(r)≤(2⋅π⋅r / 360°)⋅45°.

[0072] In other words, in each of the plurality of segments, assuming that a radius of one winding turn including the segment based on a core center of the electrode assembly is r and a width of the segment (segment width) in the winding direction is D(r), D(r) can satisfy the above formula.

[0073] In examples, D(r) may increase continuously or stepwise as r increases. Alternatively, D(r) may decrease continuously or stepwise as r increases. Alternatively, D(r) may increase continuously or stepwise and then decrease as r increases.

[0074] In other words, in each of the plurality of segments, as the radius (r) of the winding turn where the segment is located based on the core center of the electrode assembly increases, the width D(r) in the winding direction may gradually or stepwise increase, or vice versa.

[0075] In an example, in each of the plurality of segments, as the radius (r) of the winding turn increases where the segment is located based on the core center of the electrode assembly, the width D(r) in the winding direction gradually or stepwise increases and then gradually or stepwise decreases, or vice versa.

[0076] In one example, in the plurality of segments, the circumferential angle with respect to the core center of the electrode assembly may be substantially the same.

[0077] In examples, the widths of the plurality of separate tabs may increase at a constant rate in the winding direction of the electrode assembly. Alternatively or additionally, the widths of the plurality of separate tabs may increase in the radial direction depending on a distance r from the winding axis of the electrode assembly. Alternatively or additionally, the widths of the plurality of separate tabs may vary within a range of 1 mm to 11 mm.

[0078] In one example, the widths of the plurality of segments in the winding direction may increase at substantially the same rate along a direction parallel to the winding direction of the electrode assembly.

[0079] For example, in each of the plurality of segments where the segment is located based on the core center of the electrode assembly, as the radius (r) of the winding turn increases, the width in the winding direction may gradually or stepwise increase within the range of 1 mm to 11 mm.

[0080] In one example, in at least a partial region of the second section and / or the third section of the first uncoated section, the height of the first uncoated section, in particular of the plurality of separate tabs thereof, may change continuously or stepwise in the winding direction. In particular, the heights of the plurality of separate tabs may differ in two different regions. In other words, in at least a partial region of the third section, the height may change gradually or stepwise in the winding axis direction along a direction parallel to the winding direction.

[0081] For example, in at least a portion of the third section, the height in the winding axis direction may change gradually or stepwise along a direction parallel to the winding direction.

[0082] For example, the third section is divided into multiple regions along the winding direction. The height of the first uncoated section may differ between two different regions. The third section and optionally the second section may be divided into a plurality of regions with different heights along a direction parallel to the winding direction, and the height of the uncoated section in the plurality of regions may increase gradually or stepwise along a direction parallel to the winding direction.

[0083] In one example, in a height-variable area, the heights of the separate tabs can be gradually increased from a first height (h1) to an (N-1)-th height h N -1, where N is a height index and a natural number of 2 or more, in particular 2 to 30. A uniform height area in which the heights of the separate tabs at an Nth height h n be kept unchanged, where h n greater than h N -1. In other words, the first uncoated section may comprise a height-variable region in which the height of the segment is gradually increased from a first height (h1) to an N-1-th height (h N -1, N is a height index and a natural number of 2 or more), and a height-uniform area in which the height of the segment is defined as an Nth height (h n , greater than h N-1). The height of one or each of the separate tabs may be determined as a respective size in the winding direction from a continuous (rod-shaped) portion of the first uncoated portion, ie, from a location where the separate tabs are structurally different.

[0084] For example, N can be a natural number from 2 to 30.

[0085] In one example, separate tabs with the same height hk are arranged in the same winding turn around the winding axis. In other words, the height hk (k is a natural number from 1 to N) can be assigned to a plurality of segments, and the plurality of segments with the height hk can be arranged in at least one winding turn.

[0086] In one example, at least 90% of a hollow core portion of the electrode assembly with respect to a radial dimension in the radial direction after bending may remain uncovered by the separate tabs. In other words, if a starting radius of a winding turn comprising the segment with height h k (k is a natural number from 1 to N) contains, as r k is defined, the core of the electrode assembly cannot be separated for at least 90% or more of a diameter thereof from a bent portion of the segment located at the r k The hollow core portion may refer to a cylindrical cavity around the winding axis of the electrode assembly, around which the first electrode, the second electrode, and the separator disposed therebetween are wound. Hereinafter, the hollow core portion may also be referred to as a core.

[0087] In an example, where r kindicates a distance from the winding axis in a radial direction and r c indicates a radius of a central hollow portion of the electrode assembly and h k indicates the height of separate tabs located at r k where h k and r k may be such that they satisfy the following: 2 mm≤hk≤rk−α⋅rc(α is 0.90 to 1).

[0088] In other words, if a starting radius of a winding turn is defined as r k which defines the segment with height h k (k is a natural number from 1 to N), and a radius of the nucleus r c is, the height h k of the segment satisfy the above formula.

[0089] For example, the electrode assembly may include a tab skip region, a variable-height region, and a uniform-height region. The tab skip region may also be referred to as a segment skip region and may not have any separate tabs. The first portion may correspond to the tab skip region. In the variable-height region, the separate tabs may have variable heights. In the uniform-height region, the separate tabs may have a uniform height in a radial direction or in the winding direction. The plurality of separate tabs arranged in the variable-height region and the uniform-height region may be bent in the radial direction to form a bending surface region.In other words, the electrode assembly may include a segment skip region having no segment, a height-variable region in which segments have variable heights, and a height-uniform region in which segments have a uniform height along a radial direction based on a cross-section along the winding axis direction, and the plurality of segments may be arranged in the height-variable region and the height-uniform region and bent along the radial direction of the electrode assembly to form a bending surface region.

[0090] In one example, the third section may correspond to the variable-height region and the uniform-height region. Alternatively, the variable-height region and the uniform-height region may correspond to the second section and the third section, respectively. In further examples, the first section may not be divided into segments, and the segment skip region may correspond to the first section.

[0091] In one example, the third section may be divided into a plurality of segments that are independently bendable, and the height-variable region and the height-uniform region may correspond to the third section.

[0092] In one example, the second portion and the third portion may be divided into a plurality of segments that are independently bendable, and the height-variable region and the height-uniform region may correspond to the second portion and the third portion.

[0093] For example, in the height-variable area and the height-uniform area, a maximum height h max of the segments satisfy the following formula: hmax≤Wfoil−Wscrap,min−Wmargin,min−Wgap where W foil a width of a current collector foil before segments are formed; W scrap,min is a width corresponding to a minimum cutting waste margin when segments are formed by cutting the current collector foil; W margin,min is a width corresponding to a minimum meander edge of the separator; and W gap is a width corresponding to an insulation gap between one end of the separator and one end of the second electrode facing the first electrode, with the separator disposed therebetween. The parameters used herein may be as shown in the drawings.

[0094] For example, the first electrode is a positive electrode and the insulation gap may be in the range of 0.2 mm to 6 mm, or 2 mm or more, 3 mm or more, or 4 mm or more and 6 mm or less, 5.5 mm or less, or 5 mm or less.

[0095] For example, the first electrode is a negative electrode and the insulation gap may be in the range of 0.1 mm to 2 mm, or 0.1 mm or more, 0.2 mm or more, 0.5 mm or more, or 1 mm or more and 2 mm or less, 1.8 mm or less, 1.5 mm or less, or 1.2 mm or less.

[0096] For example, the minimum cutting waste margin may be in the range of 1.5 mm to 8 mm or 1.5 mm or more or 1.8 mm or more or 2 mm or more or 2.5 mm or more and 8 mm or less or 6 mm or less or 3 mm or less.

[0097] For example, the minimum meander margin can range from 0 to 1 mm, or 1 mm or less, or 0.8 mm or less, or 0.5 mm or less, or 0.2 mm or less. In the modification, the minimum cutting waste margin can be zero.

[0098] For example, the heights of the separate tabs (segments) arranged in the height-variable region may increase gradually or stepwise within the range of 2 mm to 10 mm, or 2 mm or more, 3 mm or more, 4 mm or more, or 5 mm or more and 10 mm or less, 8 mm or less, 6 mm or less, or 5 mm or less.

[0099] In one example, a ratio of a radial size in the radial direction (radial length) of the segment skip region to a radius of the electrode assembly excluding the core in the radial direction of the electrode assembly may be 10% to 40%, or 10% or more, 15% or more, 20% or more, or 25% or more, and 40% or less, 35% or less, 30% or less, or 25% or less.

[0100] In one example, a ratio of a radial size of the height-variable region to a radial size corresponding to the height-variable region and the height-uniform region in the radial direction of the electrode assembly may be 1% to 50%, or 1% or more, 5% or more, 10% or more, 20% or more, or 30% or more, and 50% or less, 40% or less, 35% or less, or 30% or less.

[0101] In one example, a ratio of a length of an electrode area corresponding to the segment skip region (segment skip region) to a total length of the first electrode in the winding (or radial) direction may be 1% to 30%, or 1% or more, 5% or more, 10% or more, 15% or more, or 20% or more, and 50% or less, 40% or less, 30% or less, or 25% or less.

[0102] In one example, a ratio of a length of an electrode area corresponding to the height-variable region to the total length of the first electrode in the winding (or radial) direction may be 1% to 40%, or 1% or more, 5% or more, 10% or more, or 20% or more, and 40% or less, 35% or less, or 30% or less, or 25% or less.

[0103] In one example, a ratio of a length of an electrode surface corresponding to the uniform height region to the total length of the first electrode in the winding (or radial) direction may be 50% to 90%, or 50% or more, 60% or more, or 70% or more, and 90% or less, 80% or less, or 70% or less.

[0104] For example, widths of the plurality of separate tabs in the winding direction and / or heights of the plurality of separate tabs in the winding axis direction (ie, widths of the plurality of segments in the winding direction and / or heights thereof in the winding axis direction) may gradually or stepwise increase along a direction parallel to the winding direction.

[0105] In one example, widths of the plurality of separate tabs in the winding direction and / or heights of the plurality of separate tabs in the winding axis direction (ie, widths of the plurality of segments in the winding direction and / or heights thereof in the winding axis direction) may gradually or stepwise increase and then gradually or stepwise decrease, or vice versa (ie, decrease and then increase) along a direction parallel to the winding direction.

[0106] In one example, the plurality of separate tabs may form a plurality of tab groups along a direction parallel to the winding direction of the electrode assembly. Separate tabs belonging to one of the tab groups may have an equal width in the winding direction and / or an equal height in the winding axis direction. Alternatively or additionally, separate tabs belonging to another of the tab groups may have increasing widths in the winding direction and / or increasing heights in the winding direction. Alternatively or additionally, three consecutive tab groups may have widths W1, W2, and W3, respectively, in the winding direction, wherein a ratio W3 / W2 is smaller than a ratio W2 / W1.

[0107] In other words, the plurality of segments may form a plurality of segment groups along a direction parallel to the winding direction of the electrode assembly, and segments belonging to the same segment group may be substantially equal to each other in terms of a width in the winding direction and a height in the winding axis direction.

[0108] For example, at least one of the widths of the segments belonging to the same segment group in the winding direction and their heights in the winding axis direction may gradually increase along a direction parallel to the winding direction of the electrode assembly.

[0109] For example, when three segment groups sequentially adjacent to each other in a direction parallel to the winding direction of the electrode assembly have widths in the winding direction of W1, W2, and W3, respectively, a combination of segment groups in which W3 / W2 is smaller than W2 / W1 may be included.

[0110] In one example, the first portion and / or the second portion may not be formed into separate tabs (i.e., may not have any) and may not be bent along a radial direction of the electrode assembly. For example, the first portion may not be divided into segments, and the first portion may not be bent along a radial direction of the electrode assembly.

[0111] For example, the second portion may not be divided into segments and the second portion may not be bent along a radial direction of the electrode assembly.

[0112] For example, an insulating coating layer, such as a polymer resin with an inorganic filler dispersed in the polymer resin, may be formed at a boundary between the active material layer and the first uncoated portion. In other words, an insulating coating layer may be formed at a boundary between the active material layer and an uncoated portion provided in a section where the bottom portion of the cut groove and the active material layer are separated.

[0113] In one example, the insulating coating layer may comprise a polymer resin and an inorganic filler dispersed in the polymer resin.

[0114] In another example, the insulating coating layer may be formed to cover a boundary portion of the active material layer and the first uncoated portion along the winding direction.

[0115] In yet another example, the insulating coating layer may be formed to cover the boundary portion of the active material layer and the first uncoated portion along the winding axis direction for a width of 0.3 mm to 5 mm.

[0116] In yet another example, an end of the insulation coating layer may be arranged within the range of -2 mm to 2 mm along the winding axis direction based on an end of the separator.

[0117] For example, the insulating coating layer may be exposed from the separator. In other words, the insulating coating layer may be partially uncovered or not overlapped by the separator when viewed in the radial direction (thickness direction).

[0118] For example, an inner side of a cut groove formed in the first uncoated portion and the insulating coating layer may be spaced apart by a distance of 0.5 mm to 2 mm. In other words, an inner side (i.e., a lower end) of the cut groove formed in the insulating coating layer may be spaced apart by a distance of 0.5 mm to 2 mm.

[0119] For example, one end of the insulation coating layer in the winding axis direction may be arranged within the range of -2 mm to +2 mm with respect to (based on) the inner side (lower end) of the cut groove.

[0120] For example, the second electrode may be coated with an active material layer in a second active material portion. One end of the second active material portion in the winding axis direction may overlap the insulating coating layer in a viewing direction in the radial direction. In other words, the second electrode may have a second active material portion coated with an active material layer along the winding direction, and one end of the second active material portion may be located between an upper end and a lower end of the insulating coating layer in the winding axis direction. The active material of the second electrode may be different from the active material of the first electrode. In particular, the active material of the second electrode may be configured to provide a different electrochemical potential than the active material of the first electrode.

[0121] In yet another example, the third portion and / or the second portion may each be formed into a plurality of separate tabs that are independently bendable. The electrode assembly may include a bending surface region formed by bending the plurality of separate tabs along a radial direction of the electrode assembly. In other words, the third portion and optionally the second portion may be divided into a plurality of independently bendable segments, and the electrode assembly may include a bending surface region formed by bending the plurality of segments along a radial direction of the electrode assembly.

[0122] For example, the number of segments that meet a virtual line parallel to the winding axis direction at any radial location of the bending surface region with respect to the winding axis (based on a core center) of the electrode assembly may be defined as the number of overlapping layers of segments at the corresponding radial location. Here, the bending surface region may include a uniform overlap layer number region in which the number of overlapping layers of segments is uniform along a radial direction (e.g., away from the winding axis toward an outer circumference or vice versa), and a decreasing overlap layer number region located outside the uniform overlap layer number region in which the number of overlapping layers of segments continuously (gradually) decreases in the radial direction, e.g., toward an outer circumference.

[0123] In one example, a radial size of the region with a uniform overlap layer number and the region with a decreasing overlap layer number may correspond to a radial size of a region in which the plurality of separate tabs are formed. In other words, a radial size (radial length) of the region with a uniform overlap layer number and the region with a decreasing overlap layer number based on the core center of the electrode assembly may correspond to a radial length of a radial region in which winding turns including the plurality of segments are arranged.

[0124] In another example, the electrode assembly may optionally include, in the following order, a segment skip region that has no separate tabs (segments), a variable-height region in which the separate tabs (segments) have variable heights, and a uniform-height region in which separate tabs (segments) have a uniform height along the radial direction. A radius from the winding axis of the electrode assembly or a radial location where the region with a uniform number of overlap layers begins may correspond to a radius where the variable-height region begins.

[0125] For example, in the uniform overlap layer number region, the number of overlap layers of the segments may be 10 to 35, or 10 or more, 12 or more, or 15 or more and 35 or less, 30 or less, 25 or less, or 20 or less.

[0126] In one example, the first electrode may be a positive electrode, and in the uniform overlap layer number region, an overlap thickness of the segments may range from 100 µm to 875 µm, or 100 µm or more, 200 µm or more, 400 µm or more, or 500 µm or more, and 875 µm or less, 650 µm or less, or 500 µm or less.

[0127] In another example, the first electrode may be a negative electrode, and in the uniform overlap layer number region, an overlap thickness of segments may range from 50 µm to 700 µm, or 50 µm or more, 100 µm or more, 200 µm or more, or 350 µm or more, and 700 µm or less, 600 µm or less, 500 µm or less, or 400 µm or less.

[0128] In yet another example, a ratio of a radial size (radial length) of the uniform overlap layer number region to a radial size (radial length) of the uniform overlap layer number region and the decreasing overlap layer number region may be 30% to 85%, or 30% or more, 40% or more, or 50% or more and 85% or less, 70% or less, or 60% or less.

[0129] For example, the electrode assembly may further include a current collector welded to the bending surface region. A welding region of the current collector may overlap the region with a uniform number of overlap layers in the radial direction of the electrode assembly by at least 50%. In other words, a welding region of the current collector may overlap the region with a uniform number of overlap layers by at least 50% in the radial direction of the electrode assembly.

[0130] In one example, the welding area of ​​the current collector may extend to overlap the area with a decreasing number of overlap layers. In other words, a region of the welding area of ​​the current collector that does not overlap the area with a uniform number of overlap layers may overlap the area with a decreasing number of overlap layers in the radial direction of the electrode assembly.

[0131] In another example, an edge of the current collector may be arranged at the bending surface area to cover one end of a bent portion of the outermost separate tabs in the radial direction of the electrode assembly. In other words, an edge of the current collector may be arranged at the bending surface area to cover one end of a bent portion of the outermost segment in the radial direction of the electrode assembly and welded to the bending surface area.

[0132] For example, the current collector is welded to the bending surface area in such a way that it has a welding strength of 2 kgf / cm 2 or more or 4 kgf / cm 2 or more, 6 kgf / cm 2 or more or 10 kgf / cm 2 or more. In other words, the welding strength of the current collector at the welding area can be 2 kgf / cm 2 or more or as specified.

[0133] Further preferably, a welding strength of the current collector at the welding area may be 4 kgf / cm 2 or more or as specified.

[0134] In yet another example, the first uncoated portion may be formed from a metal foil. The metal foil may have an elongation of 1.5% to 3.0% and a tensile strength of 25 kgf / mm 2 up to 35 kgf / mm 2 Elongation can be measured according to ASTM E8 / E8M-16a.

[0135] For example, the metal foil can be an aluminum foil.

[0136] For example, the first electrode may have a bulge length of less than 20 mm. The bulge length may be measured according to US Pat. No. 4,794,773.

[0137] For example, in the first active material portion, a ratio of a length of a short side along (parallel to) the winding axis direction to a length of a long side along (parallel to) the winding axis direction may be 1% to 4%, or 2% or more, or 3% or more and 4% or less.

[0138] In one example, a height of the second portion may decrease continuously (gradually) or stepwise in the radial direction or in the winding direction, e.g., from the core to the outer periphery of the electrode assembly.

[0139] In one example, the second section and the third section may be formed (divided) into a plurality of separate tabs (a plurality of segments) that are individually (independently) bendable. Widths and / or heights of the separate tabs in the second section may be greater than those of the separate tabs in the third section. In other words, the segments included in the second section may be greater than the segments included in the third section in terms of a width in the winding direction and / or a height in the winding axis direction.

[0140] In one example, the third portion may include a tab skip region (segment skip region) that does not have separate tabs (segments) along the winding direction of the electrode assembly.

[0141] For example, the third portion may include a plurality of tab skip regions (a plurality of segment skip regions) in the winding direction (i.e., along a direction parallel to the winding direction).

[0142] In one example, the plurality of tab skip regions may have widths that increase or decrease along the winding direction. In other words, the plurality of segment skip regions may have widths that gradually increase or decrease along a direction parallel to the winding direction.

[0143] For example, a height of the tab skip region may be equal to a height of the first section or the second section. In other words, a height of an uncoated section of the segment skip region may be substantially equal to a height of an uncoated section of the first section or an uncoated section of the second section.

[0144] For example, the plurality of segments may be located within a circumferential angle range preset based on a core center of the electrode assembly.

[0145] In one example, the plurality of segments may be located in at least two sectoral regions or polygonal regions arranged in a circumferential direction based on a core center of the electrode assembly.

[0146] For example, the multiple separate tabs on the winding axis of the electrode assembly can be located within a preset center angle, for example, 20 degrees or more. In other words, the sectoral area can have a circumferential angle of 20 degrees or more. The center angle can refer to an angle on the winding axis that corresponds to a sector of a circle and can also be referred to herein as the circumferential angle. The preset center angle can be 25 degrees or more, 30 degrees or more, or 40 degrees or more.

[0147] In one example, the second electrode may have a second active material portion coated with a different active material (active material layer) and a second uncoated portion. The second uncoated portion may be free of the other active material (active material layer) (i.e., not coated with the active material layer). The second uncoated portion may be arranged at an edge of the second electrode extending along the winding direction. The second uncoated portion may be configured to provide an electrical connection to the first electrode (i.e., at least a portion of the second uncoated portion may itself be defined as an electrode tab). The second uncoated portion may be partially divided into a plurality of separate tabs that are individually bendable (i.e.,The second uncoated portion may include a region divided into a plurality of segments that are individually (independently) bendable. The plurality of separate tabs may be bent along a radial direction of the electrode assembly to form a bending surface region, i.e., the plurality of segments may be bent along a radial direction of the electrode assembly to form a bending surface region.

[0148] The electrode assembly as described above may include any of the features of an electrode assembly specified below, particularly with reference to the drawings, unless technically inappropriate. The first electrode and the second electrode may be a positive electrode and a negative electrode, respectively. Alternatively, the first electrode and the second electrode may be a negative electrode and a positive electrode, respectively.

[0149] According to one aspect, an electrode assembly may include a first electrode, a second electrode, and a separator disposed therebetween. The first electrode, the second electrode, and the separator may be wound around a winding axis. The first electrode may include a first active material portion coated with an active material layer and a first uncoated portion free of the active material layer. The first uncoated portion may be located at an edge of the first electrode extending along a winding direction. The first uncoated portion may be partially formed into a plurality of separate tabs that are individually bendable in a radial direction of the electrode assembly. The plurality of separate tabs may be bent along the radial direction toward the winding axis of the electrode assembly to form a bending surface region.The bending surface region may include a uniform overlap layer number region in which the number of overlapping layers of the separate tabs may be 10 or more, and a decreasing overlap layer number region adjacent to the uniform overlap layer number region in which the number of overlapping layers of the separate tabs may decrease in the radial direction away from the uniform overlap layer number region.

[0150] Accordingly, an electrode assembly may be provided in which a first electrode, a second electrode, and a separator arranged therebetween are wound relative to a winding axis to define a core and an outer periphery, wherein the first electrode has a first active material portion coated with an active material layer and a first uncoated portion not coated with an active material layer along a winding direction, wherein the first uncoated portion has a region divided into a plurality of segments that are bendable toward the outer periphery of the electrode assembly independently of the core, wherein the plurality of segments are bent along a radial direction of the electrode assembly to form a bending surface region, and the bending surface region has a region with a uniform number of overlapping layers,in which the number of overlapping layers of the segments is 10 or more, and has a region with a decreasing number of overlapping layers arranged next to the region with a uniform number of overlapping layers, so that the number of overlapping layers of the segments gradually decreases along the radial direction away from the region with a uniform number of overlapping layers.

[0151] For example, the electrode assembly may include a tab skip region that has no separate tabs, a height-variable region in which the separate tabs have heights that gradually increase along the radial direction of the electrode assembly, and a height-uniform region in which the separate tabs have a uniform height along the radial direction of the electrode assembly. From a winding axis of the electrode assembly, a radial location where the region with a uniform overlap layer number begins corresponds to a radial location where the height-variable region begins. The tab skip region, the height-variable region, and the height-uniform region may be as described above.

[0152] The electrode assembly according to the above aspect may comprise any of the features of an electrode assembly specified above and below, particularly with reference to the drawings, unless technically inappropriate.

[0153] In particular, the electrode assembly according to the above aspect may implement any of the following features. An innermost region of the first uncoated portion may not be formed into separate tabs. A ratio of a radial size of the region with a uniform overlap layer number to a radial size of the region with a uniform overlap layer number and the region with a decreasing overlap layer number may be 30% to 85% or any other value specified above. A ratio of a length of an electrode area in the winding direction corresponding to the tab skip region to a total length of the first electrode in the winding direction may be 1% to 30% or any other value specified above.A ratio of a length of an electrode surface in the winding direction corresponding to the height-variable region to a total length of the first electrode in the winding direction may be 1% to 40% or any other value specified above. A ratio of a length of an electrode surface in the winding direction corresponding to the height-uniform region to a total length of the first electrode in the winding direction may be 50% to 90% or any other value specified above. In the region divided into the plurality of separate tabs, the widths of the separate tabs in the winding direction, the heights thereof in the winding axis direction, and / or a lower interior angle may gradually increase along a direction parallel to the winding direction.A height of the innermost region of the first uncoated portion or an outermost region of the first uncoated portion may be smaller than the heights of the plurality of separate tabs. The plurality of separate tabs may be curved toward the winding axis of the electrode assembly. At least 90% or more, based on a radial size, of a central cylindrical region surrounded by the electrode assembly may be uncovered (not covered) by the curved portion of the separate tabs.

[0154] According to another aspect, an electrode assembly may include a positive electrode, a negative electrode, and a separator disposed therebetween. The positive electrode, the negative electrode, and the separator may be wound around a winding axis. The positive electrode may include a positive active material portion coated with a positive active material and a first uncoated portion free of the positive active material. The first uncoated portion may be located at an edge of the positive electrode extending along a winding direction of the electrode assembly. The first uncoated portion may be configured to provide an electrical connection to the positive electrode. The first uncoated portion may include a plurality of separate tabs that are individually bendable in a radial direction of the electrode assembly.The plurality of separate tabs can be bent toward the winding axis to form a bending surface region. The bending surface region can include a region with a uniform overlap layer number, in which the number of overlapping layers of the separate tabs is uniform, and a region with a decreasing overlap layer number, arranged adjacent to the region with a uniform overlap layer number, in which the number of overlapping layers of the separate tabs decreases in a direction away from the region with a uniform overlap layer number. A combined thickness of the overlapping layers of the separate tabs in the region with a uniform overlap layer number is between 100 µm and 875 µm.

[0155] Accordingly, an electrode assembly can be provided in which a positive electrode, a negative electrode, and a separator arranged therebetween are wound based on a winding axis to define a core and an outer periphery, wherein the positive electrode has a first active material portion coated with an active material layer and a first uncoated portion not coated with an active material layer along a winding direction, wherein at least a part of the first uncoated portion itself is used as an electrode tab, wherein the first uncoated portion has a plurality of segments that are bendable independently of the core toward the outer periphery of the electrode assembly, wherein the plurality of segments are bent along a radial direction of the electrode assembly and overlapped into multiple layers to form a bending surface region,wherein the bending surface region has a region with a uniform number of overlap layers in which the number of overlapping layers of the segments is uniform, and a region with a decreasing number of overlap layers arranged adjacent to the region with a uniform number of overlap layers, so that the number of overlapping layers of the segments gradually decreases along the radial direction away from the region with a uniform number of overlap layers, and wherein in the region with a uniform number of overlap layers, an overlap thickness of segments is between 100 µm and 875 µm.

[0156] The electrode assembly according to the above aspect may also comprise any of the features of an electrode assembly specified above and below, particularly with reference to the drawings, unless this is technically inappropriate.

[0157] For example, the electrode assembly may further comprise a current collector welded to the uniform overlap layer count region such that at least a portion of a weld region of the current collector overlaps the uniform overlap layer count region and the overlapping layers of segments in the weld region have a thickness in the range of 100 µm to 875 µm or any other value specified herein.

[0158] According to another aspect, an electrode assembly may include a positive electrode, a negative electrode, and a separator disposed therebetween. The positive electrode, the negative electrode, and the separator may be wound around a winding axis. The negative electrode may include a negative active material portion coated with a negative active material and an uncoated portion free of the negative active material. The uncoated portion may be located at an edge of the negative electrode extending along a winding direction. The uncoated portion may be configured to provide an electrical connection to the negative electrode. The uncoated portion may include a plurality of separate tabs that are individually bendable in a radial direction. The plurality of separate tabs may be bent toward the winding axis to form a bending surface region.The bending surface region may include a region with a uniform number of overlap layers, in which the number of overlapping layers of the separate tabs is uniform, and a region with a decreasing number of overlap layers, adjacent to the region with a uniform number of overlap layers, in which the number of overlapping layers of the separate tabs decreases in a direction away from the region with a uniform number of overlap layers. A combined thickness of the overlapping layers of the separate tabs in the region with a uniform number of overlap layers may be between 50 µm and 700 µm.

[0159] Accordingly, an electrode assembly can be provided in which a positive electrode, a negative electrode, and a separator arranged therebetween are wound based on a winding axis to define a core and an outer periphery, wherein the negative electrode has a first active material portion coated with a layer of active material and a first uncoated portion not coated with a layer of active material along a winding direction, wherein at least a part of the first uncoated portion is used alone as an electrode tab, wherein the first uncoated portion has a plurality of segments that are bendable toward the outer periphery of the electrode assembly independently of the core, wherein the plurality of segments are bent along a radial direction of the electrode assembly and overlapped into multiple layers,to form a bending surface region, wherein the bending surface region has a region with a uniform number of overlap layers in which the number of overlapping layers of the segments is uniform, and a region with a decreasing number of overlap layers arranged next to the region with a uniform number of overlap layers, so that the number of overlapping layers of the segments gradually decreases along the radial direction away from the region with a uniform number of overlap layers, and in the region with a uniform number of overlap layers, an overlap thickness of segments is between 50 µm and 700 µm.

[0160] The electrode assembly according to the above aspect may also comprise any of the features of an electrode assembly specified above and below, particularly with reference to the drawings, unless this is technically inappropriate.

[0161] For example, the electrode assembly may further comprise a current collector welded to the uniform overlap layer count region such that at least a portion of a weld region of the current collector overlaps the uniform overlap layer count region and the overlapping layers of segments in the weld region have a thickness in the range of 50 µm to 700 µm or any other value specified herein.

[0162] According to another aspect, a battery is provided. The battery may include any of the aspects of an electrode assembly as described above. Furthermore, the electrode assembly of the battery may include any of the features specified above.

[0163] The battery may further comprise a battery case, a sealing body, and a terminal. The battery case may have an open first end surface and a second end surface opposite the first end surface, wherein the electrode assembly is housed within the battery case, and the battery case is electrically connected to one of the first electrode and the second electrode of the electrode assembly. The sealing body may be configured to seal the open first end surface of the battery case. The terminal may be electrically connected to the other of the first and second electrodes, and the terminal may have a surface exposed to the exterior of the battery case.

[0164] For example, a battery may be provided comprising: an electrode assembly in which a first electrode, a second electrode, and a separator disposed therebetween are wound based on a winding axis to define a core and an outer periphery, wherein the first electrode comprises a first active material portion coated with a layer of active material and a first uncoated portion not coated with a layer of active material along a winding direction, wherein at least a part of the first uncoated portion itself is defined as an electrode tab, wherein the first uncoated portion comprises a first portion adjacent to the core of the electrode assembly, a second portion adjacent to the outer periphery of the electrode assembly, and a third portion disposed between the first portion and the second portion,and wherein the first portion or the second portion has a lower height than the third portion in the winding axis direction; a battery case having an open end and a bottom portion opposite thereto, wherein the electrode assembly is housed in a space between the open end and the bottom portion, and the battery case is electrically connected to the first electrode or the second electrode to have a first polarity; a sealing body configured to seal the open end of the battery case; and a terminal electrically connected to the other of the first or second electrode to have a second polarity and configured to have a surface exposed to the outside.

[0165] In one example, a height of the second portion may be smaller than a height of the third portion, wherein the heights are determined in the winding axis direction. The battery case may include a bead portion pressed inward in a region adjacent to the first end surface, wherein the bead portion surfaces and the second portion are spaced apart by a predetermined distance. In other words, the second portion may have a smaller height than the third portion in the winding axis direction, the battery case may include a bead portion pressed inward in a region adjacent to the open end, and an inner periphery of the bead portion facing an upper edge of the electrode assembly and the second portion may be spaced apart by a predetermined distance.

[0166] The term "bead portion" may be figurative and may refer to a circumferential recess, circumferential groove, or recess formed on a sidewall of the battery can. The bead portion may be formed at a position near (near, proximal to, adjacent to) the side end surface of the battery casing. The bead portion may include any of the features described below, particularly with reference to the drawings.

[0167] For example, an indentation depth (D1) of the bead portion is greater than or equal to a distance (D2) from the inner periphery of the battery case to a boundary between the second portion and the third portion. In other words, an indentation depth (D1) of the bead portion and a distance (D2) from the inner periphery of the battery case to a boundary between the second portion and the third portion may satisfy a formula D1 ≤ D2.

[0168] In another example, the battery may further include a current collector electrically coupled to the third portion; and an insulator configured to cover the current collector and having an edge disposed and secured between the inner periphery of the bead portion and the current collector.

[0169] For example, a diameter of the current collector may be smaller than a minimum inner diameter of the inner circumference of the bead portion and a diameter of the current collector may be greater than or equal to an outermost diameter of the third portion.

[0170] In another example, the current collector may be arranged higher in the winding axis direction than the bead portion.

[0171] In one example, the sealing body may include a cap configured to seal the open end of the battery case, a gasket disposed between an edge of the cap and the open end of the battery case, and a crimp portion that is bent and extends into the battery case and configured to surround and retain the edge of the cap along with the gasket. The terminal may be the cap. The terminal may have a second polarity. The cap, the gasket, and the crimp portion may each include the respective features as described below, particularly with reference to the drawings.

[0172] In one example, the battery may further include a first current collector electrically connected to the first uncoated portion. The terminal may be a feedthrough terminal inserted into a perforation hole formed in the second end surface of the battery case. The feedthrough terminal may be insulated from the battery case and electrically connected to the first current collector, for example, by an insulator disposed between an inner surface of the bottom portion of the battery case and a top surface of the first current collector to electrically insulate the inner surface of the bottom portion of the battery case and the first current collector.In other words, the terminal may be a rivet terminal installed in a perforation hole formed in the bottom portion of the battery case to be insulated therefrom and electrically connected to the first current collector to have the second polarity.

[0173] In one example, the battery may further include an insulator disposed between an inner surface of the bottom portion of the battery case and a top surface of the first current collector to electrically isolate the inner surface of the bottom portion of the battery case and the first current collector.

[0174] For example, the insulator may have a thickness corresponding to a distance between the inner surface of the bottom portion of the battery case and the upper surface of the first current collector, and be in close contact with the inner surface of the bottom portion of the battery case and the upper surface of the first current collector.

[0175] In one example, the terminal may include a flat portion at a lower end thereof, the insulator may have an opening for exposing the flat portion, and the flat portion may be welded to the first current collector through the opening.

[0176] In one example, the second electrode may include a second active material portion coated with an active material layer and a second uncoated portion not coated with an active material layer along the winding direction, wherein the second electrode may have the first polarity, and wherein at least a portion of the second uncoated portion may be defined per se as an electrode tab, and the battery may further include a second current collector electrically connected to the second uncoated portion and having an edge at least partially coupled to a sidewall of the battery case.

[0177] In one example, the second electrode may include a second active material portion coated with a second active material and a second uncoated portion free of the second active material, wherein the second uncoated portion is located at an edge of the second electrode extending along the winding direction. The second uncoated portion may provide an electrical connection to the second electrode. The battery may further include a second current collector electrically connected to the second uncoated portion and having an edge electrically coupled to a sidewall of the battery case extending between the first end face and the second end face. The first current collector may have an outer diameter greater than or equal to that of the second current collector.

[0178] In other words, the second electrode may have a second active material portion coated with an active material layer and a second uncoated portion that is not coated with an active material layer along the winding direction, wherein the second electrode may have the first polarity, and wherein at least a portion of the second uncoated portion may be defined per se as an electrode tab, wherein the battery may further comprise a second current collector electrically connected to the second uncoated portion and having an edge at least partially coupled to a sidewall of the battery case, and wherein the first current collector may have an outer diameter that is greater than or equal to that of the second current collector.

[0179] For example, the first current collector and the second current collector may each be welded to the first uncoated portion and the second uncoated portion along a radial direction of the electrode assembly to form a respective weld pattern. A length of the weld pattern of the first current collector may be longer than a length of the weld pattern of the second current collector. The weld pattern may refer to a shape of an area in which the parts are welded together in a respective plan view (e.g., in a direction perpendicular to the area).

[0180] In other words, the first current collector and the second current collector may be welded to the first uncoated portion and the second uncoated portion, respectively, along a radial direction of the electrode assembly to form welding patterns, and a length of the welding pattern of the first current collector may be longer than a length of the welding pattern of the second current collector.

[0181] For example, the weld pattern of the first current collector and the weld pattern of the second current collector may be located at substantially the same distance from a core center of the electrode assembly.

[0182] For example, the battery case may have a bead portion that is pressed inward (pressed inward against an inner wall) adjacent to the first end surface of the battery case (i.e., the open end thereof). The edge of the second current collector may be electrically connected, e.g., welded, to the bead portion.

[0183] For example, a region of the second current collector that is in electrical contact with the second uncoated portion may be located further inward than an inner periphery of the bead portion.

[0184] In yet another example, the battery may include a cap having an edge supported by the bead portion and having no polarity, a seal disposed between the edge of the cap and the open end of the battery case, and a crimp portion that is bent and extends into the open end of the battery case and is configured to surround and retain the edge of the cap along with the seal. For example, the edge of the second current collector may be disposed and secured between the bead portion and the seal by the crimp portion.

[0185] For example, the edge of the second pantograph may be welded to the bead section.

[0186] In another aspect of the present disclosure, a battery is also provided, comprising: an electrode assembly in which a first electrode, a second electrode, and a separator disposed therebetween are wound based on a winding axis to define a core and an outer periphery, wherein the first electrode includes a first active material portion coated with an active material layer and a first uncoated portion not coated with an active material layer along a winding direction, wherein the first uncoated portion includes a region divided into a plurality of segments that are bendable independently of the core toward the outer periphery of the electrode assembly, wherein the plurality of segments are bent along a radial direction of the electrode assembly to form a bending surface portion,and the bending surface region includes a uniform overlap layer number region in which the number of overlapping layers of the segments is 10 or more, and a decreasing overlap layer number region located adjacent to the uniform overlap layer number region such that the number of overlapping layers of the segments gradually decreases along the radial direction away from the uniform overlap layer number region, a battery case having an open end and a bottom portion opposite thereto, the electrode assembly being housed in a space between the open end and the bottom portion, and the battery case being electrically connected to the first electrode or the second electrode to have a first polarity; a sealing body configured to seal the open end of the battery case; and a terminal,which is electrically connected to the other of the first electrode and the second electrode to have a second polarity, and is configured to have an outwardly exposed surface.,

[0187] The battery according to the above aspect may also include any of the battery features specified above and below, particularly with reference to the drawings, unless technically inappropriate. The battery may also include any of the aspects of an electrode assembly as described above. Furthermore, the electrode assembly of the battery may include any of the features specified above.

[0188] In another aspect of the present disclosure, a battery is also provided, comprising: an electrode assembly in which a positive electrode, a negative electrode, and a separator disposed therebetween are wound on the basis of a winding axis to define a core and an outer periphery, wherein the positive electrode has a first active material portion coated with an active material layer and a first uncoated portion not coated with an active material layer along a winding direction, wherein at least a part of the first uncoated portion itself is used as an electrode tab, wherein the first uncoated portion has a plurality of segments that are bendable toward the outer periphery of the electrode assembly independently of the core,wherein the plurality of segments are bent along a radial direction of the electrode assembly and overlap into multiple layers to form a bending surface region, wherein the bending surface region has a region with a uniform number of overlapping layers, in which the number of overlapping layers of the segments is uniform, and a region with a decreasing number of overlapping layers arranged adjacent to the region with a uniform number of overlapping layers, such that the number of overlapping layers of the segments gradually decreases along the radial direction away from the region with a uniform number of overlapping layers, and in the region with a uniform number of overlapping layers, an overlapping thickness of segments is between 100 µm and 875 µm; a battery case having an open end and a bottom portion opposite thereto,wherein the electrode assembly is housed in a space between the open end and the bottom portion, and the battery case is electrically connected to one of the first electrode and the second electrode to have a first polarity; a sealing body configured to seal the open end of the battery case; and a terminal electrically connected to the other of the first electrode and the second electrode to have a second polarity and configured to have an outwardly exposed surface.

[0189] The battery according to the above aspect may also include any of the battery features specified above and below, particularly with reference to the drawings, unless technically inappropriate. The battery may also include any of the aspects of an electrode assembly as described above. Furthermore, the electrode assembly of the battery may include any of the features specified above.

[0190] For example, the battery may further comprise a current collector welded to the uniform overlap layer number region such that at least a portion of a weld region of the current collector overlaps the uniform overlap layer number region, and the overlapping layers of segments in the weld region have a thickness in the range of 100 µm to 875 µm.

[0191] In another aspect of the present disclosure, a battery is also provided, comprising: an electrode assembly in which a positive electrode, a negative electrode, and a separator disposed therebetween are wound based on a winding axis to define a core and an outer periphery, wherein the negative electrode has a first active material portion coated with an active material layer and a first uncoated portion not coated with an active material layer along a winding direction, wherein at least a part of the first uncoated portion itself is used as an electrode tab, wherein the first uncoated portion has a plurality of segments that are bendable toward the outer periphery of the electrode assembly independently of the core,wherein the plurality of segments are bent along a radial direction of the electrode assembly and overlap into multiple layers to form a bending surface region, wherein the bending surface region has a uniform overlap layer number region in which the number of overlapping layers of the segments is uniform, and an overlap layer number decreasing region arranged adjacent to the uniform overlap layer number region, such that the number of overlapping layers of the segments gradually decreases along the radial direction away from the uniform overlap layer number region, and in the uniform overlap layer number region, an overlap thickness of segments is between 50 µm and 700 µm; a battery case having an open end and a bottom portion opposite thereto,wherein the electrode assembly is housed in a space between the open end and the bottom portion, and the battery case is electrically connected to one of the first electrode and the second electrode to have a first polarity; a sealing body configured to seal the open end of the battery case; and a terminal electrically connected to the other of the first electrode and the second electrode to have a second polarity and configured to have an outwardly exposed surface.

[0192] The battery according to the above aspect may also include any of the battery features specified above and below, particularly with reference to the drawings, unless technically inappropriate. The battery may also include any of the aspects of an electrode assembly as described above. Furthermore, the electrode assembly of the battery may include any of the features specified above.

[0193] For example, the battery may further comprise a current collector welded to the uniform overlap layer number region such that at least a portion of a welding region of the current collector overlaps the uniform overlap layer number region, and the overlapping layers of segments in the welding region have a thickness in the range of 50 µm to 700 µm.

[0194] In another aspect of the present disclosure, a battery pack is also provided that includes a plurality of batteries described above. Accordingly, the battery pack may include any of the battery features specified above and below, particularly with reference to the drawings, unless technically inappropriate. Each of the battery packs may include any of the aspects of an electrode assembly as described above. Furthermore, the electrode assembly included in the battery pack may include any of the features as specified above.

[0195] For example, a battery diameter to height ratio may be greater than 0.4 or greater than 0.42, greater than 0.44 or greater than 5 and less than 10, less than 8 or less than 6.

[0196] For example, the battery can have a form factor of 46110, 4875, 48110, 4880 or 4680.

[0197] For example, the battery may have a resistance of 4 milliohms or less. The resistance of the battery cell may be at least 0.5 mΩ, or at least 1.0 mΩ, and / or 3.8 mΩ or less, 3.5 mΩ or less, or 3 mΩ or less.

[0198] According to one example, in the battery pack, the plurality of batteries may be arranged in a predetermined number of columns such that an electrode terminal of each battery and an outer surface of a bottom portion of a battery case of each battery face upward.

[0199] According to another example, the battery pack may further include a plurality of bus bars configured to connect the plurality of batteries in series and parallel.

[0200] For example, the plurality of bus bars may be disposed at an upper portion of the plurality of batteries, and each of the bus bars may include a body portion configured to extend between the terminals of adjacent batteries; a plurality of first bus bar terminals configured to extend from one side of the body portion and electrically couple to an electrode terminal of a battery located on one side; and a plurality of second bus bar terminals configured to extend from the other side of the body portion and electrically couple to an outer surface of the bottom of the battery case of a battery located on the other side.

[0201] In another aspect of the present disclosure, a vehicle including the battery pack is also provided. BENEFICIAL EFFECTS

[0202] According to one example, since the uncoated portions protruding from the upper and lower portions of the electrode assembly are used as electrode tabs, it is possible to reduce the internal resistance of the battery and increase the energy density.

[0203] According to another example, since the structure of the uncoated portion of the electrode assembly is improved so that the electrode assembly does not interfere with the inner circumference of the battery in the process of forming the bead portion of the battery case, it is possible to prevent a short circuit in the cylindrical battery caused by partial deformation of the electrode assembly.

[0204] According to still another example, since the structure of the uncoated portion of the electrode assembly is improved, it is possible to prevent the uncoated portion from being torn when the uncoated portion is bent, and the number of overlapping layers of the uncoated portions is sufficiently increased to improve the welding strength of the current collector.

[0205] According to yet another example, it is possible to improve the physical properties of a region where the current collector is welded by applying a segment structure to the uncoated portion of the electrode and by optimizing the dimensions (width, height, separation pitch) of the segments to sufficiently increase the number of overlapping layers of the segments in a region used as a welding target area. As mentioned above, the plurality of segments may also be referred to herein as a plurality of separate tabs.

[0206] According to yet another example, it is possible to provide an electrode assembly with improved energy density and reduced resistance by applying a structure in which a current collector is welded over a large area to a bending surface area formed by bending the segments.

[0207] According to yet another example, it is possible to provide a cylindrical battery having an improved design for performing electrical wiring at an upper portion thereof.

[0208] According to yet another example, since the structure of the uncoated portion adjacent to the core of the electrode assembly is improved, it is possible to prevent the cavity in the core of the electrode assembly from being blocked when the uncoated portion is bent. Thus, the electrolyte injection process and the welding process of the battery case (or terminal) and the current collector can be easily performed.

[0209] According to still another example, it is possible to provide a cylindrical battery having a structure that has low internal resistance, prevents internal short circuit, and improves the welding strength of the current collector and the uncoated portion, and a battery pack and a vehicle including the cylindrical battery.

[0210] In particular, the present disclosure may provide a cylindrical battery having a diameter-to-height ratio of 0.4 or more and a resistance of 4 milliohms (mohm) or less, and a battery pack and vehicle incorporating the same. The resistance of the battery cell may be at least 0.5 mΩ, or at least 1.0 mΩ, and / or 3.8 mΩ or less, 3.5 mΩ or less, or 3 mΩ or less.

[0211] In addition, the present disclosure may have a variety of other effects, and such effects are described in each example, or any description that can be easily derived by a person skilled in the art is omitted for an effect. FIGURE DESCRIPTION

[0212] The accompanying drawings illustrate a preferred and, together with the foregoing disclosure, serve to provide a further understanding of the technical features of the present disclosure, and thus, the present disclosure should not be construed as limited to the drawings. Fig. 1 is a plan view showing a structure of an electrode used to manufacture a conventional tabless cylindrical battery. Fig. Figure 2 is a diagram showing an electrode winding process of the conventional tabless cylindrical battery. Fig. 3 is a diagram showing a welding process of a current collector to a bent surface area of ​​an uncoated portion in the conventional tabless cylindrical battery. Fig. 4 is a plan view showing a structure of an electrode according to the first. Fig. 5 is a plan view showing a structure of an electrode according to the second. Fig. 6 is a plan view showing a structure of an electrode according to the third. Fig. 7a is a plan view showing a structure of an electrode according to the fourth. Fig. Figure 7b is a diagram illustrating the definitions of width, height, and separation distance of a segment according to an example. As mentioned above, the plurality of segments may also be referred to herein as a plurality of separate tabs. Hereinafter, the term "segments" is used consistently and may refer to the separate tabs as specified in the claims. Fig. 7c is a diagram showing an arc formed by a bottom end of a segment that defines a width of the segment based on a core center of an electrode assembly when the electrode is wound according to an example. Fig. 7d is a diagram showing a relationship of heights h1, h2, h3, h4 of the segments, a core radius (r c ) and radii r1, r2, r3, r4 of a winding turn showing where the segments appear, according to an example of the present disclosure. Fig. 7e is a diagram for determining a maximum value (h max ) of the height (H) of the segments in a height-variable range of the segments. Fig. Figure 7f is a schematic diagram illustrating a formula for determining a lower interior angle (θ) of the segment. Fig. 7g is a plan view showing a modified structure of the electrode according to the fourth. Fig. 7h is a plan view showing an independent region where a plurality of segments may be located when the electrode according to the modification of the present disclosure is wound as an electrode assembly. Fig. 8a is a plan view showing a structure of an electrode according to the fifth. Fig. Figure 8b is a diagram showing the definitions of width, height, and separation distance of a segment according to another example. Fig. 8c is a plan view showing a modified structure of the electrode according to the fifth. Fig. 9 is a diagram showing segment structures according to various modifications of the present disclosure. Fig. Figure 10a is a diagram showing a cross-section of a bending surface area formed by bending the segment toward the core of the electrode assembly. Fig. 10b is a top perspective view schematically showing an electrode assembly in which the bending surface portion is formed. Fig. 10c is a graph showing results obtained by counting the number of overlapped layers of segments along a radial direction in a bending surface area of ​​a positive electrode formed at an upper portion of the electrode assemblies according to Examples 1-1 to 1-7 and a Comparative Example. Fig. 10d is a graph showing results obtained by counting the number of overlapping layers of segments along the radial direction in a bending surface area of ​​a positive electrode formed at an upper portion of the electrode assemblies according to Examples 2-1 to 2-5, Examples 3-1 to 3-4, Examples 4-1 to 4-3, and Examples 5-1 and 5-2. Fig. 10e is a graph showing results obtained by counting the number of overlapping layers of segments along the radial direction in a bending surface area of ​​a positive electrode formed at an upper portion of the electrode assemblies according to Examples 6-1 to 6-6 and Examples 7-1 to 7-6. Fig. 10f is a plan view of the electrode assembly showing a uniform range b1 of the number of overlapping layers and a decreasing range b2 of the number of overlapping layers in the bending surface area of ​​the segment according to an example. Fig. 11 is a sectional view showing a jelly roll type electrode assembly in which the electrode of the first example is applied to a first electrode (a positive electrode) and a second electrode (a negative electrode) along the Y-axis direction (winding axis direction). Fig. 12 is a sectional view showing a jelly roll type electrode assembly in which the electrode of the second example is applied to the first electrode (the positive electrode) and the second electrode (the negative electrode) along the Y-axis direction (winding axis direction). Fig. 13 is a sectional view showing a jelly roll type electrode assembly in which any one of the electrodes of the third to fifth examples (modifications thereof) is applied to the first electrode (the positive electrode) and the second electrode (the negative electrode) along the Y-axis direction (winding axis direction). Fig. 14 is a sectional view showing an electrode assembly according to still another example taken along the Y-axis direction (winding axis direction). Fig. 15 is a sectional view showing an electrode assembly according to still another example taken along the Y-axis direction (winding axis direction). Fig. 16 is a sectional view showing an electrode assembly according to still another example along the Y-axis direction (winding axis direction). Fig. 17 is a sectional view showing a cylindrical battery according to an example along the Y-axis direction. Fig. 18 is a sectional view showing a cylindrical battery according to another example along the Y-axis direction. Fig. 19 is a sectional view showing a cylindrical battery according to still another example along the Y-axis direction. Fig. 20 is a sectional view showing a cylindrical battery according to still another example along the Y-axis direction. Fig. 21 is a sectional view showing a cylindrical battery according to still another example along the Y-axis direction. Fig. 22 is a sectional view showing a cylindrical battery according to still another example along the Y-axis direction. Fig. 23 is a sectional view showing a cylindrical battery according to still another example along the Y-axis direction. Fig. 24 is a sectional view showing a cylindrical battery according to still another example along the Y-axis direction. Fig. 25 is a sectional view showing a cylindrical battery according to still another example along the Y-axis direction. Fig. 26 is a plan view showing a structure of a first current collector according to an example. Fig. 27 is a plan view showing a structure of a second current collector according to an example. Fig. Fig. 28 is a plan view showing a state in which a plurality of cylindrical batteries are electrically connected. Fig. 29 is a partially enlarged view of Fig. 28. Fig. 30 is a diagram schematically showing a battery pack according to an example. Fig. 31 is a diagram schematically showing a vehicle incorporating the battery pack according to an example. EXAMPLES

[0213] Hereinafter, preferred examples of the present disclosure will be described in detail with reference to the accompanying drawings. Before proceeding, it should be understood that the terms used in the specification and the appended claims should not be construed as limited to generic and literal meanings, but should be interpreted based on the meanings and concepts corresponding to technical aspects of the present disclosure, based on the principle that the inventor is permitted to define terms appropriately for the best explanation.

[0214] Therefore, the description proposed here is only a preferred example for the purpose of illustration only, which is not intended to limit the scope of the disclosure, so that it is understood that other equivalents and modifications could be made thereto without departing from the scope of the disclosure.

[0215] Additionally, to facilitate understanding of the invention, some components in the accompanying drawings may not be drawn to scale, but their dimensions may be exaggerated. Also, the same components may be assigned the same reference numerals in different examples.

[0216] When two tasks are declared to be "identical," this means that these tasks are "essentially identical." Accordingly, essentially identical tasks may include deviations that are technically considered small, for example, deviations within 5%. Also, when certain parameters are declared to be uniform within a range, this may mean that the parameters are uniform with respect to an average within the corresponding range.

[0217] First, an electrode assembly according to an example will be described. The electrode assembly may be a jelly-roll type electrode assembly in which a first electrode and a second electrode are wound in a sheet shape with a separator disposed therebetween. However, the present invention is not limited to a specific type of electrode assembly.

[0218] For example, at least one of the first electrode and the second electrode has an uncoated portion that is not coated with an active material at a long side end in the winding direction. At least a part of the uncoated portion is used per se as an electrode tab. The uncoated portion includes a core-side uncoated portion adjacent to a core of the electrode assembly, a circumferential uncoated portion adjacent to an outer periphery of the electrode assembly, and an intermediate uncoated portion disposed between the core-side uncoated portion and the circumferential uncoated portion.

[0219] For example, at least one of the core-side uncoated portion and the circumferential uncoated portion has a relatively lower height than the intermediate uncoated portion.

[0220] Fig. 4 is a plan view showing a structure of an electrode 40 according to the first.

[0221] Referring to Fig. 4, the electrode 40 of the first example includes a current collector 41 formed from a metal foil and an active material layer 42. The metal foil may be a metal with conductivity, for example, aluminum or copper, and is appropriately selected according to the polarity of the electrode 40. The active material layer 42 is formed on at least one surface of the current collector 41. The active material layer 42 is formed along the winding direction X. The electrode 40 includes an uncoated portion 43 at the long side end in the winding direction X. The uncoated portion 43 is a portion of the current collector 41 where it is not coated with active material. The portion of the current collector 41 where the active material is formed may be referred to as an active material portion.

[0222] In the electrode 40, the width of the active material portion in a direction along a short side of the current collector 41 may be 50 mm to 120 mm, and the length of the active material portion in a direction along a long side of the current collector 41 may be 3 m to 5 m. Accordingly, the ratio of the short side to the long side of the active material portion may be 1% to 4%.

[0223] For example, in the electrode 40, the width of the active material portion in a direction along a short side of the current collector 41 may be 60 mm to 70 mm, and the length of the active material portion in a direction along a long side of the current collector 41 may be 3 m to 5 m. Accordingly, the ratio of the short side to the long side of the active material portion may be 1.2% to 2.3%.

[0224] The ratio of the short side to the long side of the active material section is significantly smaller than the ratio of the short side to the long side of an active material section in the electrode used in a cylindrical battery with a form factor of 1865 or 2170, which is 6% to 11%.

[0225] For example, the current collector 41 can have an elongation of 1.5% to 3.0% and a tensile strength of 25 kgf / mm 2 up to 35 kgf / mm 2The elongation and tensile strength can be measured according to the measurement method of IPC-TM-650. The electrode 40 is manufactured by forming an active material layer 42 on the current collector 41 and then compressing it. During compression, a region of the uncoated portion 43 and a region of the active material layer 42 have different elongations. Therefore, swelling occurs on the electrode 40 after compression, and the swelling is greater because the electrode 40 is longer.

[0226] Optimizing the elongation and tensile strength of the current collector 41 reduces the warpage length after compression to less than 20 mm when the length of the electrode 40 is approximately 4 m. The warpage length is the maximum deflection amount of the electrode 20 in the winding direction X when the swollen electrode 20 is wound. The maximum deflection amount can be measured at a circumferential end. The electrode 40 with the elongation and tensile strength of the current collector 41 optimized has a small warpage length, so there is no meandering defect during notching of the uncoated portion 43 or winding of the electrode 40.

[0227] The current collector 41 is prone to breakage due to its low elongation. If the elongation of the current collector 41 is less than 1.5%, the rolling process efficiency of the current collector 41 deteriorates, and thus, when the electrode 40 coated with the active material layer 42 is compressed onto the current collector 41, separation may occur in the current collector 41. Meanwhile, if the elongation of the current collector 41 exceeds 3.0%, the active material portion of the electrode 40 is stretched more, and accordingly, the bulge length increases significantly. If the tensile strength of the current collector 41 is less than 25 kgf / mm 2 or more than 35 kgf / mm 2 , the electrode process efficiency of the electrode 40 is deteriorated.

[0228] The warpage phenomenon is particularly problematic in a positive electrode current collector formed from an aluminum foil. According to the present disclosure, when an aluminum foil with an elongation of 1.5% to 3.0% and a tensile strength of 25 kgf / mm 2 up to 35 kgf / mm 2 When used as a current collector, the warpage phenomenon can be suppressed. It is preferable that an active material layer be formed on the current collector to serve as a positive electrode.

[0229] For example, an insulating coating layer 44 may be formed at a boundary between the active material layer 42 and the uncoated portion 43. The insulating coating layer 44 is formed such that at least a portion of it overlaps the boundary between the active material layer 42 and the uncoated portion 43. The insulating coating layer 44 prevents a short circuit between two electrodes of different polarities and facing each other with a separator interposed therebetween. The insulating coating layer 44 has a width of 0.3 mm to 5 mm and can thus cover the boundary portion of the active material layer 42 and the uncoated portion 43. The width of the insulating coating layer 44 can vary in a winding direction of the electrode 40. The insulating coating layer 44 contains a polymer resin and may contain inorganic fillers such as Al2O3.The portion of the current collector 41 covered by the insulation coating layer 44 is not an area coated with an active material layer and thus can be regarded as an uncoated portion.

[0230] The uncoated portion 43 may include a core-side uncoated portion B1 adjacent to the core side of the electrode assembly, a circumferential uncoated portion B3 adjacent to the outer peripheral side of the electrode assembly, and an intermediate uncoated portion B2 disposed between the core-side uncoated portion B1 and the circumferential uncoated portion B3.

[0231] The core-side uncoated portion B1, the circumferential uncoated portion B3, and the intermediate uncoated portion B3 may be defined as an uncoated portion of a region adjacent to the core, an uncoated portion of a region adjacent to the outer periphery, and an uncoated portion of a remaining region, respectively, except for the above, when the electrode 40 is wound into a jelly-roll type electrode assembly.

[0232] In the following, the core-side uncoated section B1, the circumferential uncoated section B3 and the uncoated intermediate section B2 are referred to as a first section, a second section and a third section, respectively.

[0233] In one example, the first portion B1 may be an uncoated portion of the electrode region having an innermost winding turn and the second portion may be an uncoated portion of the electrode region having an outermost winding turn.

[0234] In another example, the boundary of B1 / B2 may be suitably defined as a location where the height (or change pattern) of the uncoated portion substantially changes from the core of the electrode assembly to the outer periphery, or a location with a certain percentage (%) based on the radius of the electrode assembly (e.g., 5% location, 10% location, 15% location of the radius, etc.).

[0235] The B2 / B3 boundary is a location where the height (or change pattern) of the uncoated portion substantially changes from the outer periphery of the electrode assembly to the core, or a location with a certain percentage (%) based on the radius of the electrode assembly (e.g., 85% location, 90% location, 95% location of the radius, etc.). When the B1 / B2 boundary and the B2 / B3 boundary are specified, the third portion B2 can be specified automatically.

[0236] If only the boundary of B1 / B2 is specified, the boundary of B2 / B3 may be suitably selected at a location near the periphery of the electrode assembly. In one example, the second portion may be defined as an uncoated portion of the electrode region that forms an outermost winding turn. Conversely, if only the boundary of B2 / B3 is specified, the boundary of B1 / B2 may be suitably selected at a location near the core of the electrode assembly. In one example, the first portion may be defined as an uncoated portion of the electrode region that forms an innermost winding turn.

[0237] In the first example, the height of the uncoated portion 43 is not constant and there is a relative difference in the winding direction X. That is, the height (length in the Y-axis direction) of the second portion B3 is relatively smaller than that of the first portion B1 and the third portion B2.

[0238] Fig. 5 is a plan view showing a structure of an electrode 45 according to the second embodiment.

[0239] With reference to Fig. 5, the electrode 45 of the second example differs from that of the first example only in that the height of the second portion B3 gradually decreases toward the outer circumference, and the other configuration is substantially the same.

[0240] In a modification, the second section B3 can be converted into a step shape (see dotted lines) in which the height decreases gradually.

[0241] Fig. 6 is a plan view showing a structure of an electrode 50 according to the third.

[0242] With reference to Fig. 6, in the electrode 50 of the third example, the heights of the first portion B1 and the second portion B3 are 0 or more and relatively smaller than those of the third portion B2. In addition, the heights of the first portion B1 and the second portion B3 may be the same as or different from each other.

[0243] For example, the height of the third portion B2 may have a step shape that gradually increases from the core to the outer periphery.

[0244] Patterns 1 to 7 classify the third section B2 based on the position where the height of the uncoated section 43 changes. For example, the number of patterns and the height (length in the Y-axis direction) and width (length in the X-axis direction) of each pattern can be adjusted to distribute the stress as much as possible during the bending process of the uncoated section 43. The stress distribution is intended to prevent the uncoated section 43 from being torn when the uncoated section 43 is bent toward the core of the electrode assembly.

[0245] The width (d B1 ) of the first section B1 is designed by applying a condition that the core of the electrode assembly is not covered when the patterns of the third section B2 are bent toward the core. The core means a hollow space present at the winding center of the electrode assembly.

[0246] In an example, the width (d B1 ) of the first section B1 increase proportionally to the bending length of sample 1. The bending length corresponds to the height of the sample based on the bending location (the bending point) of the sample.

[0247] For example, the width (d B1 ) of the first section B1 can be adjusted so that the radial width of the winding turns formed by the first section B1 is greater than or equal to the bending length of pattern 1. In a modified example, the width (d B1 ) of the first section B1 shall be adjusted so that the value obtained by subtracting the radial width of the winding turns formed by the first section B1 from the bending length of sample 1 is less than 0 or less than or equal to 10% of the radius of the core.

[0248] In a specific example, when the electrode 60 is used to manufacture an electrode assembly of a cylindrical battery having a form factor of 4680, the width (d B1 ) of the first section B1 is set to 180 to 350 mm according to the diameter of the core of the electrode assembly and the bending length of Sample 1.

[0249] In one example, the width of each pattern may be designed to form one or more winding turns of the electrode assembly.

[0250] In a modification, the height of the third portion B2 may have a step shape that increases from the core to the outer periphery and then decreases.

[0251] In another modification, the second section B3 may be modified to have the same structure as the second example.

[0252] In yet another modification, the pattern structure applied to the third section B2 can be extended to the second section B3 (see a dotted line).

[0253] Fig. 7a is a plan view showing a structure of an electrode 60 according to the fourth.

[0254] With reference to Fig. 7a, in the electrode 60 of the fourth example, the heights of the first portion B1 and the second portion B3 in the winding axis direction (Y) are 0 or more and relatively smaller than those of the third portion B2. In addition, the heights of the first portion B1 and the second portion B3 in the winding axis direction (Y) may be the same or different.

[0255] For example, at least a portion of the third section B2 may include a plurality of segments 61. As mentioned above, the plurality of segments may also be referred to herein as a plurality of separate tabs. Hereinafter, the term "segments" is used consistently and may refer to the separate tabs as specified in the claims. The plurality of segments 61 may gradually increase in height from the core to the outer periphery. The plurality of segments 61 have a geometric shape in which the width gradually decreases from bottom to top. For example, the geometric shape is a trapezoid. As explained later, the shape of the geometric figure may be modified in various ways.

[0256] Segment 61 may be formed by laser notching. Segment 61 may be formed by a known metal foil cutting process, such as ultrasonic cutting or punching.

[0257] In order to prevent the active material layer 42 and / or the insulation coating layer 44 from being damaged during bending of the uncoated portion 43, it is preferable in the fourth example to provide a predetermined gap between a bottom G (see Fig. 7b) a cut groove 63 between the segments 61 and the active material layer 42. This is because stress is concentrated near the bottom of the cut groove 63 when the uncoated portion 43 is bent. The gap is preferably 0.2 mm to 4 mm, more preferably 1.5 mm to 2.5 mm. The gap may also vary along a winding direction of the electrode 60. If the gap is set within the appropriate numerical range, the active material layer 42 and / or the insulating coating layer 44 near the bottom of the cut groove 63 can be prevented from being damaged by the stress generated during bending of the uncoated portion 43. In addition, the gap can prevent the active material layer 42 and / or the insulating coating layer 44 from being damaged due to tolerances during notching or cutting of the segments 61.The lower end of the cut groove 63 and the insulating coating layer 44 may be separated by 0.5 mm to 2.0 mm. When the electrode 60 is wound, the end of the insulating coating layer 44 may be positioned in the winding axis direction (Y) in the range of -2 mm to 2 mm along the winding axis direction with respect to the end of the separator. The insulating coating layer 44 can prevent a short circuit between two electrodes of different polarities and facing each other with a separator interposed therebetween, and can support the bending point when the segments 61 are bent. To improve the effect of preventing a short circuit between the two electrodes, the insulating coating layer 44 may be exposed from the separator.In addition, in order to further maximize the effect of preventing a short circuit between the two electrodes, the width of the insulating coating layer 44 may be increased so that its end in the winding axis direction (Y) is located higher than the lower end of the cut groove 63. In one example, the end of the insulating coating layer 44 in the winding axis direction may be located within the range of -2 mm to +2 mm with respect to the lower end of the cut groove 63.

[0258] The plurality of segments 61 may form a plurality of segment groups from the core to the outer periphery. The plurality of segments belonging to the same segment group may be substantially equal to each other with respect to at least one of a width, a height, and a separation distance. The width, height, and separation distance of segments belonging to the same segment group may be equal to each other.

[0259] Fig. Figure 7b is a diagram showing the definitions of width (D), height (H) and separation distance (P) of the trapezoidal segment 61.

[0260] With reference to Fig. 7b, the width (D), height (H), and separation distance (P) of the segment 61 are designed to prevent abnormal deformation of the uncoated portion 43, while sufficiently increasing the number of overlapping layers to prevent the uncoated portion 43 from being broken near the bending point during bending of the uncoated portion 43 and to improve sufficient welding strength of the uncoated portion 43.

[0261] The segment 61 is bent on a line G passing through the lower end of the cutting groove 63 or above the line G. The cutting groove 63 can make bending of the segment 61 in a radial direction of the electrode assembly smooth and easy.

[0262] The width (D) of the segment 61 is defined as a length between two locations where two straight lines extending from both sides 63b of the segment 61 meet a straight line extending from the lower portion 63a of the cutting groove 63. The height (H) of the segment 61 is defined as a shortest distance between the uppermost side of the segment 61 and a straight line extending from the lower portion 63a of the cutting groove 63. The separation distance (P) of the segment 61 is defined as a length between two locations where a straight line extending from the lower portion 63a of the cutting groove 63 meets straight lines extending from two sides 63b connected to the lower portion 63a.If the side 63b and / or the lower portion 63a is curved, the straight line may be replaced by a tangent line extending from the side 63b and / or the lower portion 63a at the intersection point where the side 63b and the lower portion 63a meet.

[0263] For example, the width (D) of segment 61 is at least 1 mm. If D is less than 1 mm, an area where segment 61 does not overlap enough to ensure welding strength, or an empty space (gap) may occur when segment 61 is bent toward the core.

[0264] For example, the width (D) of the segment 61 can be adaptively adjusted according to the radius of the winding turn where the segment 61 is located, so that the segment 61 overlaps slightly in the radial direction when the segment 61 is bent toward the core of the electrode assembly.

[0265] Fig. Figure 7c is a diagram showing an arc (A1A2) passing through the lower end (line segment Dab of Fig. 7b) of the segment 61 is formed, where the width (D) of the segment 61 is defined when the electrode 60 is wound according to an example, based on the core center O of the electrode assembly.

[0266] With reference to Fig. 7c, the arc (A1A2) has a length equal to the width (D) of segment 61 and has a circumferential angle (Φ) relative to the core center of the electrode assembly. The circumferential angle (Φ) can be defined as an angle between two line segments connecting both ends of the arc (A1A2) and the core center O on a plane perpendicular to the winding axis passing through the arc (A1A2).

[0267] If the length of the arc (A1A2) of segment 61 is equal, the circumferential angle (Φ) decreases as the radius (r) of the winding turn where segment 61 is located increases. Conversely, if the circumferential angle (Φ) of segment 61 is equal, the length of the arc (A1A2) increases proportionally as the radius (r) of the winding turn where segment 61 is located increases.

[0268] The circumferential angle (Φ) affects the bending quality of segment 61. In the drawing, a solid arrow indicates a direction of a force applied to bend segment 61, and a dotted arrow indicates a direction in which segment 61 is bent. The bending direction is toward the core center O.

[0269] The circumferential angle (Φ) of the segment 61 may preferably be 45 degrees or less, and more preferably 30 degrees or less, depending on a radius (r) of a winding turn at which the segment 61 is located, to thereby improve the uniformity of bending and prevent the occurrence of cracks.

[0270] In one aspect, the circumferential angle (Φ) of the segment 61 may gradually or stepwise increase or decrease along a radial direction of the electrode assembly within the above numerical range. In another aspect, the circumferential angle (Φ) of the segment 61 may gradually or stepwise increase and then gradually or stepwise decrease along a radial direction of the electrode assembly within the above numerical range, or vice versa. In another aspect, the circumferential angle (Φ) of the segment 61 may be substantially the same along a radial direction of the electrode assembly within the above numerical range.

[0271] According to the experiment, when the circumferential angle (Φ) of the segment 61 exceeds 45 degrees, the bending shape of the segment 61 is not uniform. The force applied to a central part of the segment 61 differs significantly from the force applied to a side part, so the segment 61 is not pressed evenly in the circumferential direction. In addition, if the pressing force is increased for uniform bending, there is a possibility that cracks may occur in the uncoated portion 43 near the cut groove 63.

[0272] In one example, the circumferential angle (Φ) of the segments 61 included in the electrode 60 is substantially the same, and the width of the segment 61 can be increased proportionally as the radius (r) of the winding turn where the segment 61 is located increases. The term "substantially identical" means that they are completely identical or that there is a deviation of less than 5%.

[0273] For example, if the radius of the electrode assembly is 22 mm, the radius of the core is 4 mm, and the segment 61 starts to be arranged from the winding turn located at a position where the radius is 7 mm, if the circumferential angle (Φ) of the segments 61 is constant at 28.6 degrees, the width (D) of the segment 61 can be increased proportionally according to the radius (r) of the winding turn where the segment 61 is located, as shown in Table 1 below. That is, the width of the segment 61 can be increased by 0.5 mm at substantially the same rate when the radius (r) of the winding turn increases by 1 mm.

[0274] For example, the width D(r) of the segment 61 located in a winding turn having a radius of r with respect to the core center O of the electrode assembly can be determined in a range satisfying the following formula 1. 1≤D(r)≤(2⋅π⋅r / 360°)⋅45°

[0275] For example, for each of the plurality of segments 61, as the radius (r) of the winding turn where the segment is located based on the core center of the electrode assembly increases, the width D(r) in the winding direction gradually or stepwise increases, or vice versa.

[0276] In another aspect, for each of the plurality of segments 61, as the radius (r) of the winding turn where the segment is located based on the core center of the electrode assembly increases, the width D(r) in the winding direction gradually or stepwise increases within the range of 1 mm to 11 mm, or vice versa.

[0277] In another aspect, for each of the plurality of segments 61, as the radius (r) of the winding turn where the segment is located based on the core center of the electrode assembly increases, the width D(r) in the winding direction gradually or stepwise increases and then gradually or stepwise decreases, or vice versa.

[0278] In another aspect, as the radius (r) of the winding turn where the segment is located based on the core center of the electrode assembly increases, the width D(r) of each of the plurality of segments 61 gradually or stepwise increases in the winding direction and then gradually or stepwise increases within the range of 1 mm to 11 mm, or vice versa.

[0279] In another aspect, a variation ratio of D(r) as the radius (r) of the coil turn where the segment is located based on the core center of the electrode assembly increases may be substantially the same or different depending on the radius (r).

[0280] In another aspect, a variation ratio of D(r) as the radius (r) of the coil turn where the segment is located based on the core center of the electrode assembly increases may be substantially the same or different depending on the radius (r) within the range of 1 mm to 11 mm.

[0281] With further reference to Fig. 7b, the height (H) of segment 61 may be 2 mm or more. If D2 is less than 2 mm, an area where segment 61 does not overlap enough to ensure welding strength or an empty space (gap) may occur when segment 61 is bent toward the core.

[0282] The height (H) of segment 61 can be determined by applying the condition that segment 61 does not cover the core when bent toward the core. For example, the height (H) of segment 61 can be adjusted so that the core can be opened outward by 90% or more of its diameter.

[0283] For example, the height (H) of segment 61 may gradually increase from the core to the outer circumference, depending on the radius of the core and the radius of the winding turn where segment 61 is located.

[0284] In an example, assuming that the height (H) of the segment 61 is gradually increased over N steps from h1 to h n increases as the radius of the winding turn increases, when a k-th height of the segment 61 h k is (k is a natural number from 1 to N), a starting radius of the winding turn, which includes the segment 61 with the height hk, r k and the radius of the nucleus r cis, the height h1 to h n of segment 61 to satisfy the following formula 2. 2 mm≤hk≤rk−α⋅rc(α is 0.90 to 1)

[0285] If the height (h k ) of the segment 61 satisfies formula 2, 90% or more of the diameter of the core can be opened outward even if the segment 61 is bent toward the core.

[0286] In one example, the total winding turn radius of the electrode 60 is 22 mm, the height of the segment 61 starts at 3 mm, the height of the segment 61 increases sequentially to 3 mm, 4 mm, 5 mm, and 6 mm each time the radius of the winding turn including the segment 61 increases by 1 mm, and the height of the segment 61 can be kept substantially constant at 6 mm in the remaining winding turn. That is, among the radii of all the winding turns, the radial direction width of a height-variable region of the segment 61 is 3 mm, and the remaining radial region corresponds to a uniform height region.

[0287] In this case, according to the radius (r c) of the core of the electrode assembly, the starting radius r1, r2, r3, r4 of the winding turn including the segment 61 with the height of 3 mm, 4 mm, 5 mm and 6 mm will be as shown in Table 2 below when α is 1 and the same sign condition is applied in a correct inequality of the above formula. Table 2 Segmenthöhe (mm) Element 3 (h1) 4 (h2) 5 (h3) 6 (h4) Core radius (r c )(mm) 2 5 (r1) 6 (r2) 7 (r3) 8 (r4) 2,5 5,5 (r1) 6,5 (r2) 7,5 (r3) 8,5 (r4) 3 6 (r1) 7 (r2) 8 (r3) 9 (r4) 3,5 6,5 (r1) 7,5 (r2) 8,5 (r3) 9,5 (r4) 4 7 (r1) 8 (r2) 9 (r3) 10 (r4)

[0288] When the segment 61 is arranged at the radial location shown in Table 2, the core is not covered by the segment 61 even if the segment 61 is bent toward the core. Meanwhile, r1, r2, r3, r4 shown in Table 2 can be shifted toward the core according to the α value. For example, when α is 0.90, r1, r2, r3, r4 can be shifted toward the core by 10% of the core radius. In this case, when the segment 61 is bent toward the core, 10% of the core radius is covered by the segment 61. r1, r2, r3, r4 shown in Table 2 are boundary values ​​of the location where the segment 61 starts. Accordingly, the location of the segment 61 can be shifted by a predetermined distance from the outer circumference further to the radius shown in Table 1.

[0289] Fig. Figure 7d is a diagram schematically showing the relationship between the heights h1, h2, h3, h4 of the segment, the core radius (r c) and the radius r1, r2, r3, r4 of the winding turn at which segment 61 begins to appear.

[0290] With reference to Table 2 and Fig. 7d together, if for example the radius (r c) of the core C3 is m, the starting radius r1, r2, r3, and r4 of the winding turn including the segment 61 with the height of 3 mm (h1), 4 mm (h2), 5 mm (h3), and 6 mm (h4) can be 6 mm, 7 mm, 8 mm, and 9 mm, respectively, and the height of the segment 61 can be maintained at 6 mm from the radius of 9 mm to the last winding turn. Furthermore, a winding turn with a radius of less than 6 mm (r1) cannot include the segment 61. In this example, since the segment 61 with a height of 3 mm (h1) closest to the core C is located away from the winding turn with a radius of 6 mm, even if the segment 61 is bent toward the core C, the segment 61 only covers the radial range from 3 mm to 6 mm, and the core C is essentially unshielded. According to the α value of Formula 2, the location of the segment 61 can be within 10% of the core radius (r c ) towards the core C.

[0291] In another aspect, as the starting radius (r) of the winding turn where the segment 61 is located based on the core center of the electrode assembly increases, a height of the segment 61 may increase at substantially the same rate or differently depending on the radius (r).

[0292] For example, the height (H) of segment 61 can satisfy formula 2 and at the same time the maximum height of the segment can be limited.

[0293] Fig. Figure 7e is a conceptual diagram for determining the maximum value (h max ) for the height (H) of segment 61 in the height-variable area of ​​segment 61.

[0294] With reference to Fig. 7e, in the winding structure of the electrode assembly, an electrode (E1) having the segment 61 faces an electrode (E2) of opposite polarity with the separator S arranged therebetween in the radial direction. Both surfaces of the electrode (E1) are covered with an active material layer (E 1,active ), and both surfaces of the electrode (E2) are also coated with an active material layer (E 2,active ) coated. For electrical insulation, the end (S end ) of the separator S by a length corresponding to the insulation gap (W gap ) corresponds, from the end (E 2,end ) of the electrode (E2) extend further outwards. In addition, the end of the electrode (E1) for electrical insulation does not extend further outwards to the end of the electrode (E2). Therefore, an area leading to the insulation gap (W gap) corresponds to the lower end of the uncoated section 43. When the electrodes (E1, E2) and the separator S are wound, the end (S end ) of the separator S. In order to expose the segment 61 from the separator S, an area (W margin,min ), which corresponds to the minimum meander edge of the separator S, is assigned to the uncoated section 43. In order to cut the segment 61, a minimum cutting waste edge (W scrap,min ) can be assigned to the end of the current collector foil. Therefore, the maximum height (h max ) of segment 61 in the height-variable area of ​​segment 61 can be determined by the following formula 3. In formula 3, W corresponds to foil to the width of the current collector foil before the current collector foil is cut. hmax=Wfoil−Wscrap,min−Wmargin,min−Wgap

[0295] For example, the insulation gap (Wgap ) be in the range of 0.2 mm to 6 mm if the first electrode is a positive electrode, and in the range of 0.1 mm to 2 mm if the first electrode is a negative electrode.

[0296] For example, the minimum cutting waste margin (W scrap,min ) in the range of 1.5 mm to 8 mm. The minimum cutting waste margin (W scrap,min ) may not be taken into account depending on the process of cutting the segment 61. For example, the cutting groove 63 may be formed so that the top surface of the segment 61 coincides with that of the current collector foil. In this case, W scrap,min Formula 3 must be zero.

[0297] For example, the minimum meander margin (W margin,min ) in the range of 0 to 1 mm.

[0298] In one example, the minimum cutting waste margin (W scrap,min ) 1.5 mm and the minimum meander edge (W margin,min) of the separator S can be 0.5 mm. Under these conditions, if the width (W foil ) of the current collector foil before forming the segment 61 is 8 mm to 12 mm and the insulation gap (W gap ) is 0.6 mm, 0.8 mm and 1.0 mm, the result of calculating the maximum height (h max ) of segment 61 using formula 3 as shown in Table 3 below.

[00301] Table 3 Element Separator ⇔ negativer Elektrodenspalt (mm) 0,6 0,8 1 StromabnehmerFolienbreite(mm) 8 5.4 5.2 5 9 6.4 6.2 6 10 7.4 7.2 7 11 8.4 8.2 8 12 9.4 9.2 9

[0299] Taking into account Table 3, the maximum height (h max ) of segment 61 in the height-variable range of segment 61 can be set to 10 mm. Therefore, in the height-variable range of segment 61, the height of segment 61 satisfies Formula 2 and can be increased stepwise or gradually along the radial direction of the electrode assembly in the range of 2 mm to 10 mm.

[0300] With further reference to Fig. 7b, the separation distance (P) of the segment 61 can be adjusted in the range of 0.05 to 1 mm. If the separation distance (P) is less than 0.05 mm, cracks may occur in the uncoated portion 43 near the bottom of the cut groove 63 due to stress when the electrode 60 moves in a winding process or the like. Meanwhile, if the separation distance (P) exceeds 1 mm, an empty space (gap) or an area where the segments 61 do not overlap enough to sufficiently ensure welding strength may occur when the segment 61 is bent.

[0301] Meanwhile, when the current collector 41 of the electrode 60 is formed of aluminum, the separation distance (P) is more preferably set to 0.5 mm or more. When the separation distance (P) is 0.5 mm or more, it is possible to prevent cracks from occurring in the lower portion of the cut groove 63 even when the electrode 60 moves at a speed of 100 mm / s or more under a tension of 300 gf or more during the winding process or the like.

[0302] According to the experimental results, when the current collector 41 of the electrode 60 is an aluminum foil with a thickness of 15 μm and the separation distance (P) is 0.5 mm or more, no cracks occur in the lower portion of the cut groove 63 when the electrode 60 moves under the above conditions.

[0303] As in Fig. 7b, the cut groove 63 is arranged between two segments 61 that are adjacent to each other in the winding direction X. The cut groove 63 corresponds to the space created when the uncoated portion 43 is removed. For example, the two ends of the lower portion of the cut groove 63 have a round shape. That is, the cut groove 63 includes a substantially flat lower portion 63a and a round portion 63c. The round portion 63c connects the lower portion 63a and the side 63b of the segment 61. In a modified example, the lower portion 63a of the cut groove 63 may be replaced with an arc shape. In this case, the sides 63b of the segments 61 may be smoothly connected by the arc shape of the lower portion 63a.

[0304] The radius of curvature of the round portion 63c may preferably be in the range of 0 to 0.5 mm, more preferably in the range of 0 to 0.1 mm, or even more preferably in the range of 0.01 mm to 0.05 mm. When the radius of curvature of the round portion 63c satisfies the above numerical range, it is possible to prevent cracks from occurring in the lower portion of the cut groove 63 while the electrode 60 moves in the winding process or the like.

[0305] In the plurality of segments 61, a lower interior angle (θ) may increase from the core to the outer periphery. The lower interior angle (θ) is an angle between a straight line extending from the lower portion 63a of the cut groove 63 and a straight line extending from the side portion 53b of the segment 61. When the segment 61 is symmetrical in the left and right directions, the lower interior angles (θ) on the left and right sides are substantially equal.

[0306] As the radius of the electrode assembly increases, the radius of curvature increases. As the lower inner angle (θ) of the segments 61 increases, the stresses generated in the radial and circumferential directions when the segment 61 is bent can be relieved. Furthermore, as the lower inner angle (θ) increases when the segment 61 is bent, its area overlapping with the segment 61 located on an inner side and the number of overlapping layers also increase together, ensuring uniform weld strength in the radial and circumferential directions and forming the bending surface area in a flat shape.

[0307] For example, the lower interior angle (θ) can be determined by the radius of the winding turn where the segment 61 is located and the width (D) of the segment 61.

[0308] Fig. Figure 7f is a schematic diagram for explaining a formula for determining the lower interior angle (θ) of segment 61.

[0309] With reference to Fig. 7f, the side of segment 61 coincides identically with a line segment AE and a line segment DE connecting the core center (E) with both endpoints A and D of a line segment AD corresponding to the width (D) of segment 61.

[0310] When the side of segment 61 extends in the most ideal direction, assuming that line segment EF is approximately equal to line segment AE and line segment DE, the lower interior angle (θrefer) of segment 61 can be approximately determined from the width (D) of segment 61 and the radius (r) of the winding turn where segment 61 is located using formula 4 below. θrefer=cos−1(0.5*Dr)

[0311] The angle in Formula 4 is a most ideal criterion angle for the lower interior angle (θrefer) of segment 61. Meanwhile, a separation distance (P) exists between adjacent segments 61 located in the same winding turn. The length of the separation distance (P) is indicated by p. Since the separation distance (P) exists between adjacent segments 61, the lower interior angle (θ) can be given a tolerance of 50% of the separation distance (P). That is, the width of the top surface BC of segment 61 can be increased by a maximum of p / 2 to the top surface B'C'. The lower interior angle (θ'), which represents the tolerance, can be expressed by Formula 5 below. The lower interior angle (θrefer) is the most ideal criterion angle BAG, and the lower interior angle (θ') is the angle B'AG', which represents the tolerance according to the separation distance (P). In formula 5, H corresponds to the height of segment 61, and p corresponds to the separation distance. θ'=tan−1(2*H*tanθrefer2*H−p*tanθrefer)

[0312] For example, the lower interior angle (θ) of the segment 61 located at each winding turn of the electrode assembly may satisfy the following formula 6. Then, when the segments 61 are bent toward the core center of the electrode assembly, the segments 61 adjacent in the circumferential direction do not interfere with each other and are bent smoothly. cos−1(0.5*Dr)≤θ≤tan−1(2*H*tanθrefer2*H−p*tanθrefer)

[0313] In one example, when the electrode 60 forms a winding structure with a diameter of 22 mm and a core radius of 4 mm, the lower interior angle of the segment 61 may gradually increase in the range of 60 degrees to 85 degrees in the height variable range.

[0314] Meanwhile, the lower interior angles of segment 61 on the left and right sides may differ from each other. Nevertheless, at least one of the lower interior angles on the left and right sides of segment 61 may be designed to satisfy Formula 6.

[0315] With further reference to Fig. 7a the width (d B1 ) of the first section B1 is designed so that the core of the electrode assembly is opened outward by 90% or more based on the diameter of the core when the segment 61 of the third section B2 is bent toward the core. The width (d B1) of the first section B1 may increase in proportion to the bending length of the segment 61 of group 1. The bending length corresponds to a length from the bending point to the uppermost side of the segment 61. For example, if the electrode 60 is used to manufacture an electrode assembly of a cylindrical battery with a form factor of 4680, the width (d B1 ) of the first section B1 can be adjusted to 180 mm to 350 mm according to the diameter of the core of the electrode assembly and the height of the segment 61 included in group 1.

[0316] The bending point of the segment 61 can be set at a line passing through the lower end of the cut groove 63 or at a position spaced upward from the line by a predetermined distance. When the segments 61 are bent toward the core at a position spaced a predetermined distance from the lower end of the cut groove 63, the segments can more easily overlap in the radial direction. When the segments 61 are bent, a segment located on an outer side based on the center of the core presses a segment on an inner side. Meanwhile, when the bending point is spaced a predetermined distance from the lower end of the cut groove 63, a segment on an inner side is pressed by a segment on an outer side in the winding axis direction, so the segments overlap better. For example, the separation distance of the bending point can be 1 mm or less.The minimum height of the segment 61 is 2 mm, and thus a ratio of the separation distance to the minimum height of the segment 61 can be 50% or less.

[0317] In one example, the width of each segment group can be designed to form the same winding turn of the electrode assembly. Here, the winding turn can be counted based on the end of the first section B1 when the electrode 60 is in a wound state.

[0318] In another modified example, the width of each segment group may be designed to form at least one winding turn of the electrode assembly.

[0319] In yet another modification, the width and / or height and / or separation distance of the segment 61 belonging to the same segment group may be gradually and / or stepwise and / or irregularly increased or decreased within the group or between the adjacent groups.

[0320] Groups 1 to 8 are just one example of segment groups included in the third section B2. The number of groups, the number of segments 61 included in each group, and the width of each group can be desirably adjusted so that the segments 61 overlap in multiple layers to distribute the stress as much as possible during the bending process of the uncoated section 43 and to sufficiently ensure the welding strength with a current collector.

[0321] In another modification, the height of the second section B3 may be reduced gradually or stepwise, as in the first example and the second example.

[0322] In yet another modification, the segment structure of the third section B2 is extendable to the second section B3 (see dotted line). In this case, the second section B3 may also include a plurality of segments like the third section B2. For example, the segment structure of the second section B3 may be substantially the same as the segment group on the outermost side of the third section B2. In this case, the segments included in the second section B3 and the third section B2 may be substantially equal in terms of width, height, and separation distance. In one modification, the segment of the second section B3 may have a width and / or a height and / or a separation distance that are greater than those of the third section B2.

[0323] In the third section B2, the region (groups 1 to 7) in which the height of the segment 61 gradually increases based on the winding direction of the electrode 60 is defined as a height-variable region of the segment, and the segment group at the last (group 8) may be defined as a height-uniform region in which the height of the segment is kept uniform.

[0324] That is, if in the third section B2 the height of the segment 61 gradually increases from h1 to h n is increased, corresponds to the area in which segments 61 with a height of h1 to h N -1 (N is a height index and a natural number of 2 or more), a height-variable area, and the area in which segments 61 with a height of h ncorresponds to a uniform height region. The relationship of the height-variable region and the uniform height region to the length of the electrode 60 in the winding direction will be described later with reference to specific examples.

[0325] When the electrode plate 60 is used to manufacture an electrode assembly of a cylindrical battery having a form factor of 4680, the width (d B1) of the first section B1 can be 180 to 350 mm. The width of group 1 can be 35 to 40% of the width of the first section B1. The width of group 2 can be 130 to 150% of the width of group 1. The width of group 3 can be 120 to 135% of the width of group 2. The width of group 4 can be 85 to 90% of the width of group 3. The width of group 5 can be 120 to 130% of the width of group 4. The width of group 6 can be 100 to 120% of the width of group 5. The width of group 7 can be 90 to 120% of the width of group 6. The width of group 8 can be 115 to 130% of the width of group 7. The width (d B3 ) of the second section B3 can be 180 to 350 mm, like the width of the first section B1.

[0326] The reason the widths of groups 1 to 8 do not show a constant increase or decrease pattern is that the segment width gradually increases from group 1 to group 8, but the number of segments included in the group is limited to an integer, and the thickness of the electrode exhibits a slight variation along a winding direction. Accordingly, the number of segments in a specific segment group can be reduced. Therefore, the widths of the groups can exhibit an irregular change pattern from the core to the outer circumference, as in the example above.

[0327] That is, assuming that the width in the winding direction for each of the three segment groups consecutively adjacent to each other in the circumferential direction of the electrode assembly is W1, W2, and W3, respectively, it is possible to include a combination of segment groups in which W3 / W2 is smaller than W2 / W1.

[0328] In the specific example, groups 4 to 6 correspond to the above case. 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 smaller than 120 to 130%.

[0329] According to another modification, when the uncoated portion 43 of the electrode 60 has a segment structure, the electrode 60 may include a segment skip region 64 in which some of the plurality of segments are regularly or irregularly omitted, as shown in Fig. 7g shown.

[0330] For example, the segment skip region 64 may be provided multiple times. In one example, the width of the segment skip region 64 may be constant from the core to the outer periphery. In another example, the width of the segment skip region 64 may increase or decrease regularly or irregularly from the core to the outer periphery. For example, the height of the uncoated portion present in the segment skip region 64 may correspond to the height of the first portion B1 and / or the second portion B3.

[0331] The number of segments 61 present between the segment skip areas 64 may be at least one. As in Fig. 7g, the electrode 60 may have an uncoated portion in which the number of segments 61 present between the segment skip regions 64 increases from the core to the outer periphery.

[0332] For example, the width of the segment skip area 64 may be set such that when the electrode 60 is as in Fig. 7h, segments located in each winding turn may be located in a preset independent region 66 with respect to the core center C of the electrode assembly 65.

[0333] That is, the plurality of segments 61 may be located within a plurality of independent regions 66 with respect to the core center C when the electrode assembly 65 is viewed in the winding axis direction. The number of independent regions 66 may be changed to 2, 3, 4, 5, or the like.

[0334] For example, the independent region 66 may have a sectoral shape. In this case, the angle between the independent regions 66 may be substantially the same. Additionally, the circumferential angle (δ) of the independent region 66 may be 20 degrees or more, optionally 25 degrees or more, optionally 30 degrees or more, optionally 35 degrees or more, or optionally 40 degrees or more.

[0335] In a modified example, the independent region 66 may have a geometric shape such as a square, a rectangle, a parallelogram, a trapezoid, or the like.

[0336] In the present disclosure, the shape of the segment 61 may be modified variously.

[0337] Fig. 8a is a plan view showing the structure of an electrode 70 according to the fifth.

[0338] With reference to Fig. 8a, the electrode 70 of the fifth example has substantially the same configuration as that of the first example, except that the shape of the segment 61' is different. Therefore, unless otherwise stated, the configuration of the fourth example can be equally applied to the fifth example.

[0339] Segment 61' has a geometric shape with substantially the same width at the top and bottom. For example, segment 61' may have a rectangular shape.

[0340] Fig. Figure 8b is a diagram showing the definition of the width, height and separation distance of the rectangular segment 61'.

[0341] With reference to Fig. 8b, the width (D), height (H), and separation distance (P) of the segment 61' can be adjusted to prevent the uncoated portion 43 from being abnormally deformed, while sufficiently increasing the number of overlapping layers of the uncoated portion 43 to prevent the uncoated portion 43 from being torn during bending and to improve the welding strength with a current collector. Abnormal deformation means that the uncoated portion does not maintain a straight state below the bending point and is irregularly collapsed and deformed.

[0342] The width (D) of the segment 61' is defined as a length between two points where two straight lines extending from both sides of the segment 61' meet a straight line extending from the lower portion 63a of the cutting groove 63. The height (H) of the segment 61' is defined as a shortest distance between the uppermost side of the segment 61' and the straight line extending from the lower portion 63a of the cutting groove 63. The separation distance (P) of the segment 61' is defined as a length between two points where the straight line extending from the lower portion 63a of the cutting groove 63 meets straight lines extending from two sides 63b connected to the lower portion 63a.If the side 63b and / or the lower portion 63a is curved, the straight line may be replaced by a tangent line extending from the side 63b and / or the lower portion 63a at the intersection point where the side 63b and the lower portion 63a meet.

[0343] For example, the conditions regarding the width (D), height (H), and separation distance (P) of segment 61' are essentially the same as those of the fourth example and will therefore not be described again. However, since segment 61' has a rectangular shape, the lower interior angle of segment 61' can be constant at 90 degrees.

[0344] Similar to the electrode 60 of the fourth example, the electrode 70 according to the fifth example may also include a segment skip region 64 in which some of the plurality of segments are regularly or irregularly omitted, as in Fig. 8c shown.

[0345] In addition, when the electrode 70 including the segment skip region 64 is wound into an electrode assembly, the segments may be located within a plurality of independent regions 66, as shown in Fig. 7h shown.

[0346] As in the fourth example and the fifth example, when the third section B2 and the second section B3 include a plurality of segments 61, 61', the shape of each segment 61, 61' can be modified differently.

[0347] For example, the segment can be deformed into different shapes as long as at least one of the following conditions is met. Condition 1: The width of the lower section is greater than the width of the upper part. Condition 2: The width of the lower section and the width of the upper part are equal. Condition 3: The width remains the same from bottom to top. Condition 4: The width decreases from bottom to top. Condition 5: The width decreases and then increases from bottom to top. Condition 6: The width increases and then decreases from bottom to top. Condition 7: The width increases from bottom to top and remains constant. Condition 8: The width decreases from bottom to top and remains constant. Condition 9: The interior angle of one side of the lower section and the interior angle of the other side are equal

[0348] Here, the interior angle can be defined as an angle formed by the side portion of the segment based on the width direction of the bottom portion of the segment. If the side portion is curved, the interior angle is defined as an angle between a tangent line drawn at the bottom end of the curve and the width direction of the bottom portion of the segment.

[0349] Condition 10: The interior angle of one side of the lower segment and the interior angle of the other side are different from each other.

[0350] Condition 11: The interior angle of one side of the lower segment and the interior angle of the other side of the lower segment are an acute angle, a right angle, and an obtuse angle, respectively.

[0351] Condition 12: Left and right symmetrical with respect to the winding axis direction.

[0352] Condition 13: Left and right asymmetric with respect to the winding axis direction.

[0353] Condition 14: The side section has a straight line shape.

[0354] Condition 15: The side segment is curved.

[0355] Condition 16: The side segment is convex outwards.

[0356] Condition 17: The side segment is inwardly convex.

[0357] Condition 18: The corner of the upper section and / or the lower section has a structure where a straight line meets a straight line.

[0358] Condition 19: The corner of the upper section and / or the lower section has a structure where a straight line meets a curve.

[0359] Condition 20: The corner of the upper section and / or the lower section has a structure where one curvature meets another curvature

[0360] Condition 21: The corner of the upper section and / or the lower section has a round structure.

[0361] Fig. 9 is a diagram exemplifying the shapes of segments according to modified examples of the present disclosure.

[0362] As shown in the drawing, the segment can have various geometric shapes, with a dotted line connecting the lower sections of the cutting grooves on both sides serving as the base. The geometric figure has a structure connecting one or more straight lines, one or more curves, or a combination thereof. In one example, the segment can have a polygonal shape, a circular shape, or various shapes combined therewith.

[0363] In particular, the segment may have a left-right symmetric trapezoidal shape (ⓐ); a left-right asymmetric trapezoidal shape (ⓑ); a parallelogram shape (ⓒ); a triangular shape (ⓛ); a pentagonal shape (ⓚ); an arc shape (ⓔ); or an elliptical shape (ⓕ).

[0364] Since the shape of the segment does not match the Fig. 9, it may be converted into other polygonal shapes, other circular shapes, or a combination thereof to satisfy at least one of the conditions 1 to 21 described above.

[0365] In the polygonal shapes ⓐ, ⓑ, ⓒ, ⓚ and ⓛ of the segment, the corner of the upper section and / or the lower section can be a shape where a straight line meets a straight line or a round shape (see the enlarged view of the corner of the upper section and the lower section of the shape ⓐ).

[0366] In the polygonal shapes ⓐ, ⓑ, ⓒ, ⓚ, and ⓛ of the segment and the curved shapes ⓔ and ⓕ of the segment, the interior angle (θ1) on one side of the lower portion and the interior angle (θ2) on the other side thereof may be equal to or different from each other, and the interior angle (θ1) on one side of the lower portion and the interior angle (θ2) on the other side thereof may be any of an acute angle, a right angle, or an obtuse angle, respectively. The interior angle is an angle at which the base and side of a geometric figure meet. If the side is a curve, the straight line can be replaced by a tangent line extending at a point where the base and side meet.

[0367] The shape of the side section of the segment with a polygonal shape can be modified in various ways.

[0368] In one example, the side portion of the segment shape ⓐ can be converted into an outwardly convex curve as in the shape ⓓ or into a curve inset into the segment as in the shape ⓖ or ⓙ.

[0369] In another example, the side portion of the segment shape ⓐ can be converted into a curved straight line recessed into the segment, such as in the shape ⓗ or ⓘ. Although not shown, the side portion of the segment shape ⓐ can be converted into a curved straight line that is convex outward.

[0370] In the segment shapes ⓓ, ⓖ, ⓙ, ⓗ and ⓘ in which the side portion is differently modified, the interior angle (θ1) on one side of the lower portion and the interior angle (θ2) on the other side thereof may be equal to or different from each other, and the interior angle (θ1) of one side of the lower portion and the interior angle (θ2) on the other side thereof may be any of an acute angle, a right angle or an obtuse angle, respectively.

[0371] The width of the segment can show different change patterns from bottom to top.

[0372] In one example, the width of the segment may be kept constant from bottom to top (shape ⓒ). In another example, the width of the segment may gradually decrease from bottom to top (shapes ⓐ, ⓑ, ⓓ, ⓔ, ⓕ, and ⓖ). In yet another example, the width of the segment may gradually decrease from bottom to top and then increase (shapes ⓘ and ⓙ). In yet another example, the width of the segment may gradually increase from bottom to top and then decrease (shape ⓚ). In yet another example, the width of the segment may gradually decrease from bottom to top and then be kept constant (shape ⓗ). Although not shown, the width of the segment may gradually increase from bottom to top and be kept constant.

[0373] Meanwhile, among the forms of Fig. 9, a polygonal shape with a flat top may be rotated 180 degrees. In one example, when the segment shape ⓐ, ⓑ, ⓓ, or ⓖ is rotated 180 degrees, the width of the segment may gradually increase from bottom to top. In another example, when the segment shape ⓗ is rotated 180 degrees, the width of the segment may be kept constant from bottom to top and then gradually increase.

[0374] In the above examples (modifications), according to another aspect of the present disclosure, it is possible to change the shapes of the segments 61, 61' differently depending on the region of the third section B2. In one example, a circular shape (e.g., semicircle, ellipse, etc.) that is favorable for stress distribution is applied to a region where stress is concentrated, and a polygonal shape (e.g., a rectangle, trapezoid, parallelogram, etc.) with the largest area can be applied to a region where stress is relatively low.

[0375] In the above examples (modifications), the segment structure of the third portion B2 can also be applied to the first portion B1. However, when the segment structure is applied to the first portion B1, if the segments 61, 61' of the third portion B2 are bent according to the radius of curvature of the core, the end of the first portion B1 may be bent toward the outer circumference, which is called reverse forming. Therefore, the first portion B1 does not have a segment, or even if the segment structure is applied to the first portion B1, it is desirable to control the width and / or height and / or separation distance of the segments 61, 61' as small as possible, taking into account the radius of curvature of the core, so that no reverse forming occurs.

[0376] According to yet another aspect of the present disclosure, after winding the electrode 60, 70 into an electrode assembly, the segments exposed at the upper and lower portions of the electrode assembly may be overlapped into multiple layers along the radial direction of the electrode assembly to form a bending surface region.

[0377] Fig. 10a is a schematic diagram showing a cross-section of the bending surface area F formed when the segment 61 is bent toward the core C of the electrode assembly 80. In Fig. 10a shows only a left-hand side cross-section of the bending surface region F relative to the winding axis of the electrode assembly 80. The bending surface region F can be formed at both the upper and lower portions of the electrode assembly 80. Fig. 10b is a top perspective view schematically showing the electrode assembly 80 on which the bending surface region F is formed.

[0378] With reference to Fig. 10a and Fig. 10b, the bending surface region F has a structure in which the segments 61 are overlapped into multiple layers in the winding axis direction. The overlap direction is the winding axis direction (Y). Region 1 is a segment skip region (the first section B1) that has no segment, and regions 2 and 3 are regions where the winding turn including the segment 61 is located. Region 2 is a height-variable region in which the height of the segment 61 is variable, and region 3 is a height-uniform region in which the height of the segment is kept uniform to the outer periphery of the electrode assembly. As described later, the radial lengths of region 2 and region 3 can be variable. Meanwhile, the uncoated portion (the second portion B3) included in at least one winding turn with the outermost winding turn may not include a segment structure.In this case, the second section B3 may be excluded from area 3.

[0379] In area ②, the heights of the segments 61 can be adjusted step by step from the minimum height h1 (= hmin) to the maximum height h n (= h max ) in the radius range from r1 to r n of the electrode assembly 80. The height-variable range in which the heights of the segments 61 are variable is r1 to r n . From the radius r n up to the radius R of the electrode assembly 80, the heights of the segments 61 are uniform at h n Uniform height means that the height deviation is within 5%.

[0380] At any radial location of the region 2 and the region 3, the number of overlapping layers of the segments 61 varies depending on the radial location. In addition, the number of overlapping layers of the segments 61 can be determined based on the width of the region 2, the minimum height (h1), and the maximum height (h N -1) of the segments in the height-variable range of the segment 61 and the height change amount (Δh) of the segments 61. The number of overlapping layers of the segments 61 is the number of segments that meet a virtual line when the virtual line is drawn in the winding axis direction at any radial location of the electrode assembly 80.

[0381] For example, the number of overlapping layers of the segments 61 at each position of the bending surface area F can be optimized appropriately for the required welding strength of the current collector by adjusting the height, width, and separation distance of the segment 61 according to the radius of the winding turn including the segment 61.

[0382] First, when the minimum height (h1) of the segment in the height variable region (2) of the segment 61 is the same, how the number of overlapping layers of the segments 61 is changed along the radial direction of the bending surface region F according to the change of the maximum height III of the segment 61 will be described by specific examples.

[0383] The electrode assemblies of Examples 1-1 to 1-7 are manufactured. The electrode assemblies of these examples have a radius of 22 mm and a core diameter of 4 mm. The positive electrode and the negative electrode included in the electrode assembly have the Fig. 7a. That is, the segment has a trapezoidal shape. The second section B3 of the positive electrode and the negative electrode has no segment. The length of the second section B3 is 2% to 4% compared to the total length of the electrode. The positive electrode, the negative electrode, and the separator are connected by the method described with reference to Fig. 2. The winding turns range from 48 to 56 turns, while the winding turns of these examples are 51 turns. The thicknesses of the positive electrode, the negative electrode, and the separator are 149 µm, 193 µm, and 13 µm, respectively. The thickness of the positive electrode and the negative electrode is the thickness including the thickness of the active material layer. The thicknesses of the positive electrode current collector plate and the negative electrode current collector plate are 15 µm and 10 µm, respectively. The lengths of the positive electrode and the negative electrode in the winding direction are 3948 mm and 4045 mm, respectively.

[0384] In each example, the minimum height of segment 61 is set to 3 mm, so the height-variable range (2) of segment 61 starts at a radius of 5 mm. Furthermore, in each example, the height of segment 61 is increased by 1 mm for every 1 mm increase in radius, and the maximum height of segment 61 is changed differently from 4 mm to 10 mm.

[0385] Specifically, in Example 1-1, the height-variable range (2) of segment 61 is 5 mm to 6 mm, and the height of segment 61 is variable at a radius of 3 mm to 4 mm. In Example 1-2, the height-variable range (2) of segment 61 is 5 mm to 7 mm, and the height of segment 61 is variable from 3 mm to 5 mm. In Example 1-3, the height-variable range (2) of segment 61 is 5 mm to 8 mm, and the height of segment 61 is variable from 3 mm to 6 mm. In Example 1-4, the height-variable range (2) of segment 61 is 5 mm to 9 mm, and the height of segment 61 is variable from 3 mm to 7 mm. In Example 1-5, the height-variable range (2) of segment 61 is 5 mm to 10 mm, and the height of segment 61 is variable from 3 mm to 8 mm. In Example 1-6, the height-variable range (2) of segment 61 is 5 mm to 11 mm, and the height of segment 61 is variable from 3 mm to 9 mm.In Example 1-7, the height-variable range (2) of segment 61 is 5 mm to 12 mm, and the height of segment 61 is variable from 3 mm to 10 mm. In Examples 1-1 to 1-7, the height of segment 61 is uniform from the radius corresponding to the upper limit of the height-variable range (2) to the outer circumference. In one example, in Example 1-7, the height of segment 61 located within a radius of 12 mm to 22 mm is uniform as 10 mm. Meanwhile, in the electrode assembly of Comparative Example, the height of segment 61 is maintained at a single height of 3 mm from the radius of 5 mm to the radius of 22 mm.

[0386] Fig. Figure 10c is a graph showing the results of counting the number of overlapping layers of the segments along the radial direction in the bending surface area F of the positive electrode formed at the upper portion of the electrode assemblies according to Examples 1-1 to 1-7 and the Comparative Example. The bending surface area of ​​the negative electrode shows substantially the same result. The horizontal axis of the graph is the radius based on the core center, and the vertical axis of the graph is the number of overlapping layers counted at each radius point, and it is the same in the Fig. 10d and Fig. 10e, which will be explained later.

[0387] With reference to Fig. 10c shows the uniform range b1 of the number of overlapping layers of the segment commonly used in Examples 1-1 to 1-7 and Comparative Example 1. The uniform range b1 of the number of overlapping layers is a radial region of a flat area in each diagram. The length of the uniform range b1 of the number of overlapping layers increases as the maximum height of the segment decreases, and the uniform range (b1') of the number of overlapping layers of the comparative example is the longest. Meanwhile, the number of overlapping layers of the segments increases as the maximum height III of the segment increases. That is, as the maximum height III of the segment increases, so the width of the height-variable region (2) of the segment increases, the number of overlapping layers of the segments increases, but the width of the uniform range b1 of the number of overlapping layers decreases.On an outer side of the uniform overlap layer number region b1, there appears the overlap layer number decreasing region b2, in which the number of overlapped layers decreases as the radius increases. The overlap layer number decreasing region b2 is a radial region in which the number of overlapped layers decreases as the radius of the electrode assembly increases. The uniform overlap layer number region b1 and the overlap layer number decreasing region b2 are adjacent and complementary to each other in the radial direction. That is, as the length of one region increases, the length of the other region decreases. In addition, the amount of decrease in the number of overlapped layers in the uniform overlap layer number decreasing region b2 is proportional to the distance from the uniform overlap layer number region b1.

[0388] From the perspective of the number of overlapping layers of the segments, in Examples 1-1 to 1-7, the number of overlapping layers of the segments is 10 or more in the area b1 with a uniform number of overlapping layers. A range in which the number of overlapping layers of the segments is 10 or more can be set as a preferential welding target range. The welding target range is a range in which at least a part of the current collector can be welded.

[0389] In Examples 1-1 to 1-7, the region b1 with a uniform number of overlap layers starts from a radius point where the height-variable region (2) of the segment begins. That is, the height-variable region (2) starts at a radius of 5 mm and extends to the outer perimeter.

[0390] The following Table 4 shows, in Examples 1-1 to 1-7 and Comparative Example 1 for the positive electrode, calculation results of a ratio of the length of the segment jump area (c, ① in Fig. 10a) to the radius (ba) of the electrode assembly excluding the core, a ratio (e / f) of the length of the uniform region b1 of the number of overlapping layers to the length (f) from the radius point (5 mm) at which the uniform region of the number of overlapping layers begins to an outermost point of the electrode assembly (22 mm), a ratio (d / f) of the length of the height-variable region (d) of the segment (d) to the length (f) from the radius point (5 mm) at which the uniform region of the number of overlapping layers begins to the outermost point (22 mm) of the electrode assembly, a ratio (h) of the length of the electrode region corresponding to the segment jump region (first section B1) to the total length of the electrode, a ratio (i) of the length of the electrode region corresponding to the height-variable region to the total length of the electrode, a ratio (j) of the electrode region corresponding to the uniform height region,to the total length of the electrode and the like.

[0391] Except that the negative electrode has a difference of 0.1 to 1.2% with respect to the parameter h, the remaining parameters are essentially the same as the positive electrode. The sum of the proportions h, i, and j is slightly different from 100%. This is because there is an area that has no segment in the second section B3, which corresponds to the outer circumferential uncoated portion of the electrode. For example, in Example 1-1, there is no segment in the second section B3, which corresponds to approximately 4% of the total electrode length. In Table 4, a to f are parameters based on the length in the radial direction, and h, i, and j are parameters based on the length in the longitudinal direction of the electrode before it is wound into an electrode assembly. In addition, the parameters corresponding to the ratio (%) are values ​​rounded to the first decimal place.These points are essentially the same as in Tables 5 and 6, which are explained later.

[0392] As can be seen in Examples 1-1 to 1-7 of Table 4, the number of overlapping layers of the segments is 11 to 26, and the ratio (d / f) of the height-variable region (d) to the radius region (f) containing the segment is 6% to 41%. In addition, the ratio (e / f) of the region (e) with a uniform number of overlapping layers to the radius region (f) containing the segment is 47% to 82%. In addition, the ratio (c / (ba)) of the segment skip region (c, ① in Fig. 10a) to the radius (ba) of the electrode assembly excluding the core is 15%. In addition, the ratio of the length of the electrode area corresponding to the segment skip region (first section B1) to the total length of the electrode is 6%, the ratio of the length of the electrode area corresponding to the height-variable region to the total length of the electrode is 3% to 32%, and the ratio of the length of the electrode area corresponding to the height-uniform region to the total length of the electrode is 59% to 87%.

[0393] The number of overlapping layers (g) of the uniform overlapping layer number region is 10 or more for all examples 1-1 to 1-7. The uniform overlapping layer number region (e) decreases as the height-variable region (d) of the segment increases, but the number of overlapping layers (g) of the segments increases in the uniform overlapping layer number region (e). For example, the uniform overlapping layer number region (e) in which the number of overlapping layers (g) of the segments is 10 or more can be set as a welding target region.

[0394] For cylindrical batteries with form factors of 1865 and 2170, the radius of the electrode assembly is approximately 9 mm to 10 mm. Therefore, for a conventional cylindrical battery, the radial length of the segment region (f) cannot be secured at the level of 17 mm as in Examples 1-1 to 1-7, and the length of the region (e) with a uniform overlapping layer number, where the number of overlapping segment layers is 10 or more, cannot be secured at the level of 8 mm to 14 mm. This is because, in the conventional cylindrical battery, when the core radius is 2 mm, which is the same as in Examples 1-1 to 1-7, the radial area in which the segments can be arranged is essentially only 7 mm to 8 mm. In addition, in the conventional cylindrical battery, the length of the electrode in the winding direction is 600 mm to 980 mm.Such a short electrode length is only approximately 15% to 24% of the length of the electrode used in Examples 1-1 to 1-7 (the positive electrode is 3948 mm, the negative electrode is 4045 mm). Accordingly, the numerical ranges for the parameters h, i, and j cannot be easily derived from the design specifications of the conventional cylindrical battery.

[0395] Next, it is explained through concrete examples how the number of overlapping layers of the segments in the radial direction of the bending surface area F changes according to the change of the minimum height (h1) of the segment when the maximum height (h N ) of the segment in the height-variable area of ​​the segment is equal to (② in Fig. 10a).

[0396] The electrode assemblies of Examples 2-1 to 2-5 have a radius of 22 mm and the core C has a diameter of 4 mm. In the height-variable region of the segment 61 (② in Fig. 10a) the minimum height (h1) is 4 mm and the maximum height (h N ) is changed from 6 mm to 10 mm by 1 mm. Therefore, in the electrode assemblies of Examples 2-1 to 2-5, the width of the height-variable area (② in Fig. 10a) of the segment 2 mm, 3 mm, 4 mm, 5 mm or 6 mm and the segment skip area (① of Fig. 10a) is a radial area with a radius of 2 mm to 6 mm.

[0397] The electrode assemblies of Examples 3-1 to 3-4 have a radius of 22 mm and the core C has a diameter of 4 mm. In the height-variable range (② of Fig. 10a) of segment 61, the minimum height (h1) is 5 mm and the maximum height (h N ) is changed from 7 mm to 10 mm by 1 mm. Therefore, in the electrode assemblies of Examples 3-1 to 3-4, the width of the height-variable area (② in Fig. 10a) of the segment 2 mm, 3 mm, 4 mm or 5 mm and the segment skip area (① in Fig. 10a) is a radial area with a radius of 2 mm to 7 mm.

[0398] The electrode assemblies of Examples 4-1 to 4-3 have a radius of 22 mm and the core C has a diameter of 4 mm. In the height-variable region (② in Fig. 10a) of segment 61, the minimum height (h1) is 6 mm and the maximum height (h) is changed from 8 mm to 10 mm by 1 mm. Therefore, in the electrode assemblies of Examples 4-1 to 4-3, the width of the height-variable region ② in Fig. 10a) of the segment 2 mm, 3 mm or 4 mm and the segment skip area (① in Fig. 10a) is a radius range with a radius of 2 mm to 8 mm.

[0399] The electrode assemblies of Examples 5-1 to 5-2 have a radius of 22 mm and the core C has a diameter of 4 mm. In the height-variable region (② in Fig. 10a) of segment 61, the minimum height (h1) is 7 mm and the maximum height (hN ) is changed from 9 mm to 10 mm by 1 mm. Therefore, in the electrode assemblies of Examples 5-1 to 5-2, the width of the height-variable area ② in Fig. 10a) of the segment 2 mm or 3 mm and the segment skip area (① in Fig. 10a) is a radius range with a radius of 2 mm to 9 mm.

[0400] Fig. Figure 10d is a graph showing the results of counting the number of overlapping segment layers along the radial direction in the bending surface area F of the positive electrode formed on the upper portion of the electrode assemblies of Examples 2-1 to 2-5, Examples 3-1 to 3-4, Examples 4-1 to 4-3, and Examples 5-1 to 5-2. The bending surface area of ​​the negative electrode also shows substantially the same results.

[0401] In Fig. 10d, the graph (a) shows the result of counting the number of overlapping layers of the segments along the radial direction in the bending surface area F for Examples 2-1 to 2-5, the graph (b) shows the result for Examples 3-1 to 3-4, the graph (c) shows the result for Examples 4-1 to 4-3, and the graph (d) shows the result for Example 5-1 to Example 5-2.

[0402] With reference to Fig. In Figure 10d, the uniform region b1 of the number of overlapping layers of the segment appears common in all examples. The uniform region b1 of the number of overlapping layers is a radial region of a flat area in the diagram. The length of the uniform region b1 of the number of overlapping layers increases as the maximum height (h N) of the segment decreases when the minimum height (h1) of the segment is equal. In addition, the length of the uniform area b1 of the number of overlapping layers increases when the minimum height (h1) of the segment decreases when the maximum height (h N ) of the segment is equal. Meanwhile, in the uniform range b1 of the number of overlapping layers, the number of overlapping layers of the segments increases as the maximum height (h N ) of the segment increases. Furthermore, in the examples, the area b2 with a decreasing number of overlap layers appears next to the area b1 with a uniform number of overlap layers.

[0403] In the examples, the number of overlapping layers of the segments in the area b1 with a uniform number of overlapping layers is always 10 or more. For example, the area where the number of overlapping layers of segments is 10 or more can be set as a preferential welding target area.

[0404] In the examples, the area b1 with a uniform number of overlap layers begins at a radial point where the height-variable area (② in Fig. 10a) of the segment begins. In examples 2-1 to 2-5, the height-variable area (② in Fig. 10a) of the segment at 6 mm and extends to the outer circumference. In examples 3-1 to 3-4, the height-variable area (② in Fig. 10a) of the segment at 7 mm and extends to the outer circumference. In examples 4-3 to 4-3, the height-variable area (② in Fig. 10a) of the segment at 8 mm and extends to the outer circumference. In examples 5-1 to 5-2, the height-variable area (② in Fig. 10a) of the segment at 9 mm and extends to the outer circumference.

[0405] The following Table 5 shows the results of calculating various parameters such as a ratio (e / f) of the length of the uniform region of the number of overlapping layers to the length from the radius point (6 mm, 7 mm, 8 mm, 9 mm) where the uniform region of the number of overlapping layers starts to the outermost point (22 mm) of the electrode assembly, a ratio (d / f) of the length of the height-variable region (②) to the length from the radius point (6 mm, 7 mm, 8 mm, 9 mm) where the uniform region of the number of overlapping layers starts to the outermost point (22 mm) of the electrode assembly, and the like for Examples 2-1 to 2-5, Examples 3-1 to 3-4, Examples 4-1 to 4-3, and Examples 5-1 to Example 5-2.

[0406] See Example 2-5, Example 3-4, Example 4-3 and Example 5-2 of Table 5 together with the Fig. 10a and Fig. 10d, the maximum height (h N ) of the segment in the height-variable region (2) of the segment is 10 mm, but the minimum height (h1) of the segment increases by 1 mm at 4 mm, 5 mm, 6 mm, and 7 mm, and the length of the height-variable region (2) decreases by 1 mm at 6 mm, 5 mm, 4 mm, and 3 mm. In the four examples, the ratio (e / f) of the uniform area of ​​the number of overlapping layers is the maximum in Example 2-5 as 69% and the minimum in Example 5-2 as 38%, and the number of overlapping layers of the uniform area of ​​the number of overlapping layers is the same in all examples.

[0407] From the results shown in Table 5, when the maximum height (h N) of the segment is equal to the minimum height (h1) of the segment, and the minimum height (h1) of the segment decreases, it is understood that as the width of the height-variable region (2) of the segment increases, the width of the uniform region increases proportionally to the number of overlapping layers. This is because when the minimum length (h1) of the segment is smaller, the radial position where the segment starts is closer to the core, so the region where the segments are stacked extends toward the core.

[0408] As shown in Table 5, the number of overlapping layers of the segments ranges from 16 to 26, the ratio (d / f) of the height-variable region (2) of the segment ranges from 13% to 38%, and the ratio of the region (e / f) with a uniform number of overlapping layers ranges from 31% to 69%. Furthermore, the ratio (c / (ba)) of the segment skip region (1) to the radius (ba) of the electrode assembly excluding the core ranges from 20% to 35%. In addition, the ratio of the length of the electrode area corresponding to the segment skipping area (1) to the total length of the electrode is 10% to 20%, the ratio of the length of the electrode area corresponding to the height variable area (2) to the total length of the electrode is 6% to 25%, and the ratio of the length of the electrode area corresponding to the height uniform area (2) to the total length of the electrode is 62% to 81%.

[0409] In the form factors of the 1865 and 2170 cylindrical batteries, the radius of the electrode assembly is approximately 9 mm to 10 mm. Therefore, it is impossible to secure the radial length of the segment region (f) at the level of 13 mm to 16 mm as in the examples, and it is impossible to secure the length of the segment skip region (c, ①) at the level of 4 mm to 7 mm, while the length of the region (e) with a uniform overlap layer number, in which the number of overlapping segment layers is 10 or more, is secured at the level of 5 mm to 11 mm. This is because, in the conventional cylindrical battery, when the radius of the core is 2 mm, which is the same as in the examples, the radial area in which the segments can be arranged is essentially only 7 mm to 8 mm. In addition, in the conventional cylindrical battery, the length of the electrode in the winding direction is 600 mm to 980 mm.Such a short electrode length in the examples is only approximately 15% to 24% of the electrode length (the positive electrode is 3948 mm, the negative electrode is 4045 mm). Accordingly, the numerical ranges for the parameters h, i, and j cannot be easily derived from the design specifications of the conventional cylindrical battery.

[0410] Next, it will be explained through specific examples how the number of overlapping layers of the segments is changed according to the diameter of the core C of the electrode assembly along the radial direction of the bending surface area F when the minimum height (h1) and the maximum height (h N ) of the segment are equal in the height-variable area (②) of the segment.

[0411] The electrode assemblies of Examples 6-1 to 6-6 have a radius of 22 mm, and the core C has a radius of 4 mm. In the height-variable region (2) of the segment 61, the minimum height (h1) of the segment is 3 mm, and the maximum height (h N ) of the segment is changed from 5 mm to 10 mm by 1 mm. Therefore, in the electrode assemblies of Examples 6-1 to 6-6, the width of the height-variable region (2) of the segment is 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, and 7 mm, respectively, and the segment skip region (1) is a radial region with a radius of 4 mm to 7 mm.

[0412] The electrode assemblies of Examples 7-1 to 7-6 have a radius of 22 mm, and the core C has a radius of 2 mm. In the height-variable region (2) of the segment 61, the minimum height (h1) of the segment is 3 mm, and the maximum height (h N) of the segment is changed by 1 mm from 5 mm to 10 mm. Therefore, in the electrode assemblies of Examples 7-1 to 7-6, the width of the height-variable region (2) of the segment is 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, and 7 mm, respectively, and the segment skip region (1) is a radial region with a radius of 2 mm to 5 mm.

[0413] Fig. Figure 10e is a graph showing the results of counting the number of overlapping layers of the segments along the radial direction in the bending surface area F of the positive electrode formed on the upper portion of the electrode assembly for Examples 6-1 to 6-6 and Examples 7-1 to 7-6. Essentially the same results are shown in the bending surface area of ​​the negative electrode.

[0414] In Fig. 10e, diagram (a) shows the results of counting the number of overlapping layers of segments along the radial direction in the bending surface region F for Examples 6-1 to 6-6, and diagram (b) shows the results for Examples 7-1 to 7-6.

[0415] With reference to Fig. 10e, the uniform area b1 of the number of overlapping layers of the segment appears common in all examples. The uniform area b1 of the number of overlapping layers is a radial area of ​​a flat region in the diagram. The radial length of the uniform area b1 of the number of overlapping layers increases as the maximum height (h N ) of the segment decreases when the minimum height (h1) of the segment is equal. Meanwhile, in the uniform range b1 of the number of overlapping layers, the number of overlapping layers of the segments increases when the maximum height (h N) of the segment increases. In the examples, the area b2 with decreasing number of overlap layers appears next to the area b1 with a uniform number of overlap layers.

[0416] In the examples, the number of overlapping layers of the segments in the area b1 with a uniform number of overlapping layers is 10 or more for all examples. For example, an area where the number of overlapping layers of segments is 10 or more can be set as a preferential welding target area.

[0417] In the examples, the area b1 with a uniform number of overlap layers begins from a radius point where the height-variable area (2) of the segment begins. In Examples 6-1 to 6-6, the radius where the area (2) with variable segment height begins is 7 mm, and in Examples 7-1 to 7-6, the radius where the area (2) with variable segment height begins is 5 mm.

[0418] The following Table 6 shows the results of calculation of various parameters, including a ratio (e / f) of the length of the uniform overlap layer number region to the length from the radius point (7 mm, 5 mm) at which the uniform overlap layer number region starts to the outermost point (22 mm) of the electrode assembly, a ratio (d / f) of the length of the height-variable region (②) to the length from the radius point (7 mm, 5 mm) at which the uniform overlap layer number region starts to the outermost point (22 mm) of the electrode assembly, for Examples 6-1 to 6-6 and Examples 7-1 to 7-6, and the like.

[0419] Considering examples 6-6 and 7-6 in Table 6 together with Fig. 10a are the minimum height (h1) and the maximum height (h N) of the segment in the height-variable region (②) of the segment are 3 mm and 10 mm, respectively. However, in Example 6-6, the radius of the core is larger by 2 mm compared to that of Example 7-6. Therefore, in Example 6-6, the uniform region (e) of the number of overlapping layers and the segment region (f) are smaller by 2 mm compared to those of Example 7-6, and the number of overlapping layers of the segments in the uniform region of the number of overlapping layers is the same. These results are derived from the difference in the radius of the core. From the results shown in Table 6, it is understood that when the width of the height-variable region (②) of the segment is the same, since the radius (a) of the core is smaller, the ratio (d / f) of the height-variable region (②) decreases, while the ratio (e / f) of the uniform region of the number of overlapping layers increases.

[0420] As shown in Table 6, the number of overlapping layers of the segments ranges from 13 to 26, the ratio (d / f) of the height-variable region (2) ranges from 12% to 47%, and the ratio (e / f) of the length of the region with a uniform number of overlapping layers ranges from 40% to 76%. Furthermore, the ratio (c / (ba)) of the segment skip region (1) to the radius (ba) of the electrode assembly excluding the core ranges from 15% to 17%. In addition, the ratio of the length of the electrode area corresponding to the segment skipping area (1) to the total length of the electrode is 6%, the ratio of the length of the electrode area corresponding to the height-variable area (2) to the total length of the electrode is 7% to 32%, and the ratio of the length of the electrode area corresponding to the height-uniform area (3) to the total length of the electrode is 59% to 83%.

[0421] For cylindrical batteries with form factors of 1865 and 2170, the radius of the electrode assembly is approximately 9 mm to 10 mm. Therefore, it is impossible to secure the radial length of the segment region (f) at a height of 15 mm to 17 mm and the length of the segment skip region (1) at a height of approximately 3 mm, while at the same time, the length of the region (e) with a uniform overlapping layer number, in which the number of overlapping segment layers is 10 or more, is secured at a height of 6 mm to 13 mm as in the examples. This is because in the conventional cylindrical battery, when the core radius is 2 mm to 4 mm, which is the same as in the examples, the radial range in which the segments can be arranged is essentially only 5 mm to 8 mm. In addition, in the conventional cylindrical battery, the length of the electrode in the winding direction is 600 mm to 980 mm.Such a short electrode length in the examples is only approximately 15% to 24% of the electrode length (the positive electrode is 3948 mm, the negative electrode is 4045 mm). Accordingly, the numerical ranges for the parameters h, i, and j cannot be easily derived from the design specifications of the conventional cylindrical battery.

[0422] Comprehensively considering the data in Tables 4 to 6, the number of overlapping layers of the segments in the uniform range of the number of overlapping layers of the segment can be 11 to 26. In addition, the ratio (d / f) of the height-variable region (2) of the segment can be 6% to 47%. In addition, the ratio (e / f) of the region with a uniform number of overlapping layers can be 31% to 82%. In addition, the ratio (c / (ba)) of the length of the segment skip region (1) to the radius of the electrode assembly excluding the core can be 15% to 35%. In addition, the ratio of the length of the electrode area corresponding to the segment skip region (1) to the total length (in the winding direction length) of the electrode can be 6% to 20%. In addition, the ratio of the length of the electrode area corresponding to the height-variable region (②) of the segment to the total length of the electrode can be 3% to 32%.In addition, the ratio of the length of the electrode area corresponding to the uniform height area (③) of the segment to the total length of the electrode can be 59% to 87%.

[0423] Meanwhile, the parameters described by Tables 4 to 6 can be varied according to design factors, including the radius (a) of the core; the radius (b) of the electrode assembly; the minimum height (h1) and the maximum height (h N ) in the height variable region (②) of the segment; the amount of change (Δh) of the height of the segment per 1 mm radius increase; the thickness of the positive electrode, the negative electrode, and the separator; and the like.

[0424] Therefore, within the uniform range of the number of overlapping layers of the segment, the number of overlapping layers of the segments can be expanded to 10 to 35. The ratio (d / f) of the height-variable region (2) of the segment can be expanded to 1% to 50%. In addition, the ratio (e / f) of the region with a uniform number of overlapping layers can be expanded to 30% to 85%. In addition, the ratio (c / (ba)) of the length of the segment skip region (1) to the radius of the electrode assembly excluding the core can be expanded to 10% to 40%. In addition, the ratio of the length of the electrode area corresponding to the segment skip region (1) to the total length (in the winding direction length) of the electrode can be expanded to 1% to 30%. In addition, the ratio of the length of the electrode area corresponding to the height-variable area (②) of the segment to the total length of the electrode can be extended to 1% to 40%.In addition, the ratio of the length of the electrode area corresponding to the uniform height area (3) of the segment to the total length of the electrode can be increased to 50% to 90%. In the above examples, the height index N is at the maximum height (h). N ) of the segment in the height-variable region (2) and the height-uniform region (3) ranges from 2 to 8. For example, referring to Table 4, the height index N for Examples 1-1 and 1-7 is 2 and 8, respectively. However, the height index N may vary according to the height change amount ("h") of the segment in a radial direction of the electrode assembly. When the radial length of the height-variable region (2) is fixed, the height index N increases accordingly, and vice versa, as the height change amount ("h") of the segment decreases. For example, the height index N may be expanded to the range of 2 to 20, and optionally further to the range of 2 to 30.

[0425] In the bending surface area F formed on the top and bottom of the electrode assembly, the area with uniform overlap layer number can be used as a welding target area of ​​the current collector.

[0426] For example, the welding area of ​​the current collector overlaps the area with a uniform number of overlap layers in the radial direction of the electrode assembly by at least 50%. Here, a higher overlap ratio is preferable.

[0427] For example, the remaining area of ​​the welding area of ​​the current collector that does not overlap the area with uniform overlap layer number may overlap the area with decreasing overlap layer number adjacent to the area with uniform overlap layer number in the radial direction.

[0428] More preferably, the remaining area of ​​the welding area of ​​the current collector that does not overlap the uniform overlap layer number area may overlap a portion of the decreasing overlap layer number area in which the number of overlapping layers of segments is 10 or more.

[0429] When the current collector is welded to the area where the number of overlapping segment layers is 10 or more, it is preferable in terms of weld strength and preventing damage to the separator or active material layer during welding. It is particularly useful when welding the current collector using a high-power laser with high penetration properties.

[0430] When the uniform overlap layer number region where 10 or more segments are stacked is welded to the current collector with a laser, even if the laser power is increased to improve the welding quality, the uniform overlap layer number region absorbs most of the laser energy to form weld beads, so it is possible to prevent the separator and the active material layer under the bending surface region F from being damaged by the laser.

[0431] In addition, the number of overlapping segment layers in the laser-irradiated area is 10 or more, so that weld beads with sufficient volume and thickness are formed. Accordingly, the weld strength can be sufficiently secured and the weld interface resistance can be reduced to a level suitable for rapid charging.

[0432] When welding the current collector, the laser power can be determined by the desired weld strength between the bending surface area F and the current collector. The weld strength increases proportionally with the number of overlapping segment layers. This is because with an increase in the number of overlapping layers, the volume of weld beads formed by the laser increases. Weld beads are formed when the current collector material and the segment material are fused together. Therefore, when the volume of weld beads is large, the coupling between the current collector and the bending surface area is stronger, and the contact resistance of the weld interface is reduced.

[0433] For example, the welding strength can be 2 kgf / cm 2 or more, preferably 4 kgf / cm 2or more. The maximum welding strength may depend on the performance of a laser welding device. As an example, the welding strength may preferably be 8 kgf / cm 2 or less, more preferably 6 kgf / cm 2 or less, but the present invention is not limited thereto.

[0434] When the welding strength satisfies the above numerical range, the physical properties of the welding interface do not deteriorate even if strong vibration along the winding axis direction and / or the radial direction acts on the electrode assembly, and the resistance of the welding interface may also be reduced due to the sufficient volume of the weld beads.

[0435] The laser power to meet the weld strength condition varies depending on the laser device and can be appropriately adjusted in the range of 250 W to 320 W or 40% to 100% of the maximum laser power specification provided by the corresponding device.

[0436] The welding strength can be expressed as a tensile force per unit area (kgf / cm 2) of the current collector can be defined when the current collector begins to detach from the bending surface area F. Specifically, after the current collector is completely welded, a tensile force can be applied to the current collector, but the magnitude of the tensile force can be gradually increased. When the tensile force exceeds a threshold, the segment begins to detach from the weld interface. At this time, the value obtained by dividing the tensile force applied to the current collector by the area of ​​the current collector corresponds to the weld strength.

[0437] In the bending surface area F, segments are stacked in multiple layers, and according to the above examples, the number of overlapping layers of the segments can be increased from 10 sheets minimum to 35 sheets maximum.

[0438] The thickness of the positive electrode current collector (foil) forming an uncoated portion 43 may range from 10 µm to 25 µm, and the thickness of the negative electrode current collector (foil) forming an uncoated portion 43 may range from 5 µm to 20 µm. Therefore, the bending surface area F of the positive electrode may include a range where the total overlap thickness of the segments is 100 µm to 875 µm. Furthermore, the bending surface area F of the negative electrode may include a range where the total overlap thickness of the segments is 50 µm to 700 µm.

[0439] Fig. 10f is a plan view showing an electrode assembly in which the uniform range b1 of the number of overlapping layers and the decreasing range b2 of the number of overlapping layers are illustrated in the bending surface area F of the segments 61, 61' according to an example.

[0440] With reference to Fig. 10f, the area between two circles indicated by thick solid lines corresponds to the bending area F of the segment, and the area between two circles indicated by dashed lines corresponds to the uniform area b1 of the number of overlapping layers in which the number of overlapping layers of the segments is 10 or more, and the outer area of ​​the uniform area b1 of the number of overlapping layers corresponds to the decreasing area b2 of the number of overlapping layers.

[0441] In one example, when the current collector (Pc) is welded to the bending surface region F, a weld pattern (Wp) is formed on the surface of the current collector (Pc). The weld pattern (Wp) may be a line pattern or a dot array pattern. The weld pattern (Wp) corresponds to the weld area and may overlap the uniform overlap layer number region b1 of the segment along the radial direction by 50% or more. Accordingly, a part of the weld pattern (Wp) may be included in the uniform overlap layer number region b1, and the rest of the weld pattern (Wp) may be included in the decreasing overlap layer number region b1 outside the uniform overlap layer number region b1. Of course, the entire weld pattern (Wp) may overlap the uniform overlap layer number region b1 to maximize weld strength and reduce resistance in the weld area.

[0442] The area of ​​the bending surface region F can be defined as the sum of the area of ​​the region with a uniform number of overlap layers b1 of the segment and the area of ​​the region with a decreasing number of overlap layers b2. Since the ratio (e / f) of the region with a uniform number of overlap layers b1 is 30% to 85%, preferably 31% to 82%, the ratio of the area of ​​the region with a uniform number of overlap layers b1 to the area of ​​the bending surface region F can be 9% (302 / 1002) to 72% (852 / 1002), preferably 10% (312 / 1002) to 67% (822 / 1002).

[0443] For example, the edge of the portion where the current collector (Pc) contacts the bending surface region F may cover the end of the segments 61, 61' bent toward the core C in the last winding turn of the uniform height region (3). In this case, since a welding pattern (Wp) is formed in a state where the segments 61, 61' are pressed by the current collector (Pc), the current collector (Pc) and the bending surface region F are strongly coupled. As a result, the segments 61, 61' stacked in the winding axis direction adhere closely to each other, thereby reducing the resistance at the welding interface and preventing the segments 61, 61' from lifting.

[0444] Meanwhile, the bending direction of the segment may be opposite to that described above. That is, the segment may be bent from the core to the outer circumference. In this case, the pattern in which the height of the segment is changed along the winding direction (X-axis direction) may be opposite to that of the previous examples (modified examples). For example, the height of the segment may be gradually reduced from the core to the outer circumference. In addition, the structure applied to the first section B1 and the structure applied to the second section B3 may be interchanged.For example, the height change pattern of the segment can be designed so that the height of the segment gradually decreases from the core side to the outer circumference side, but the end of the segment is not exposed from the outer circumference of the electrode assembly when the segment closest to the outer circumference of the electrode assembly is bent toward the outer circumference.

[0445] The electrode structure of the above examples (modifications) can be applied to at least one of the first electrode and the second electrode with different polarities included in the jelly-roll type electrode assembly or another type of electrode assembly known in the art. Furthermore, when the electrode structure of the above examples (modifications) is applied to any one of the first electrode and the second electrode, the conventional electrode structure can be applied to the other. Furthermore, the electrode structures applied to the first electrode and the second electrode may not be identical but may be different from each other.

[0446] For example, when the first electrode and the second electrode are a positive electrode and a negative electrode, respectively, any of the above examples (modifications) can be applied to the first electrode, and the conventional electrode structure (see Fig. 1) can be applied to the second electrode.

[0447] As another example, when the first electrode and the second electrode are a positive electrode and a negative electrode, respectively, any of the above examples (modifications) may be selectively applied to the first electrode, and any of the above examples (modifications) may be selectively applied to the second electrode.

[0448] In the present disclosure, a positive electrode active material coated on the positive electrode and a negative electrode active material coated on the negative electrode may use any active material known in the art without limitation.

[0449] In one example, the positive electrode active material may comprise an alkali metal compound represented by a general formula A[A x M y ]O 2+z (A comprises at least one element selected from Li, Na and K; M comprises at least one element selected from Ni, Co, Mn, Ca, Mg, Al, Ti, Si, Fe, Mo, V, Zr, Zn, Cu, Al, Mo, Sc, Zr, Ru and Cr; x ≥ 0, 1 ≤ x+y ≤ 2, 0.1 ≤ z ≤ 2; and the stoichiometric modulus x, y and z are selected so that the compound maintains electrical neutrality).

[0450] In another example, the active material of the positive electrode may be an alkali metal compound xLiM 1 O2-(1-x)Li2M 2 O3, which is disclosed in US6,677,082, US6,680,143, et al., where M 1 at least one element with an average oxidation state of 3; M 2 at least one element with an average oxidation state of 4; and 0 ≤ x ≤ 1).

[0451] In yet another example, the positive electrode active material may be lithium metal phosphate represented by a general formula Li a M 1 x Fe 1-x M 2 y P 1-y M 3 z O 4-z expressed (M 1 comprises at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg and Al; M 2comprises at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg, Al, As, Sb, Si, Ge, V and S; M 3 comprises a halogen element, optionally comprising F; 0 a ≤ 2, 0 ≤ x ≤ 1, o ≤ y 1, o ≤ z 1; the stoichiometric coefficient a, x, y and z are selected such that the compound maintains electrical neutrality), or Li3M2(PO4)3 (M comprises at least one element selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Al, Mg and Al).

[0452] For example, the active material of the positive electrode may comprise primary particles and / or secondary particles in which the primary particles are aggregated.

[0453] In one example, the negative electrode active material may use carbon material, lithium metal or a lithium metal compound, silicon or a silicon compound, tin or a tin compound, or the like. Metal oxides such as TiO2 and SnO2 with a potential of less than 2 V can also be used as the negative electrode active material. Both low-crystalline carbon and high-crystalline carbon or the like can be used as the carbon material.

[0454] The separator may use a porous polymer film, for example, a porous polymer film made of a polyolefin-based polymer such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, ethylene / methacrylate copolymer, or the like, or laminates thereof. As another example, the separator may use a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, or the like.

[0455] A coating layer of inorganic particles can be incorporated into at least one surface of the separator. It is also possible for the separator itself to be made from a coating layer of inorganic particles. Particles in the coating layer can be coupled with a binder, creating an interstitial volume between adjacent particles.

[0456] The inorganic particles may be made of an inorganic material having a dielectric constant of 5 or more. As a non-limiting example, the inorganic particles may comprise at least one material selected from the group consisting of Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3 (PLZT), PB(Mg3Nb 2 / 3 )O3-PbTiO3 (PMN-PT), BaTiO3, hafnium oxide (HfO2), SrTiO3, TiO2, Al2O3, ZrO2, SnO2, CeO2, MgO, CaO, ZnO and Y2O3.

[0457] The structure of the electrode assembly is described in detail below according to an example.

[0458] Fig. 11 is a sectional view showing a jelly roll type electrode assembly 80 in which the electrode 40 of the first example is applied to the first electrode (the positive electrode) and the second electrode (the negative electrode) along the Y-axis direction (winding axis direction).

[0459] The electrode assembly 80 can be formed by the method described with reference to Fig. 2. For convenience of description, the protruding structures of the first uncoated portion 43a and the second uncoated portion 43b extending from the separator are illustrated in detail, and the winding structures of the first electrode, the second electrode, and the separator are not shown. The first uncoated portion 43a, which protrudes upward, extends from the first electrode, and the second uncoated portion 43b, which protrudes downward, extends from the second electrode.

[0460] The patterns in which the heights of the first and second uncoated portions 43a, 43b change are schematically illustrated. That is, the height of the uncoated portion may vary irregularly depending on the position at which the cross section is cut. For example, in a cross section where the sides of the trapezoidal segments 61, 61' or the cutting grooves 63 are cut, the height of the uncoated portion in the cross section is lower than the height H of the segments 61, 61'. Accordingly, it is understood that the heights of the uncoated portions illustrated in the drawings showing the cross section of the electrode assembly correspond to the average of the heights (H in Fig. 7b and Fig. 8b) of the uncoated section contained in each winding turn.

[0461] With reference to Fig. 11, the first uncoated portion 43a includes a first portion B1 adjacent to the core of the electrode assembly 80, a second portion B3 adjacent to the outer periphery of the electrode assembly 80, and a third portion B2 disposed between the first portion B1 and the second portion B3.

[0462] The height (length in the Y-axis direction) of the second portion B3 is relatively smaller than the height of the third portion B2. Accordingly, an internal short circuit can be prevented from occurring because the bead portion and the second portion B3 contact each other while the bead portion of the battery case is pressed near the second portion B3.

[0463] The second uncoated portion 43b has the same structure as the first uncoated portion 43a. In a modification, the second uncoated portion 43b may have a conventional electrode structure or an electrode structure of other examples (modifications).

[0464] The ends 81 of the first uncoated portion 43a and the second uncoated portion 43b may be bent in the radial direction of the electrode assembly 80, for example, from the outer periphery toward the core. At this time, the second portion B3 may not be significantly bent.

[0465] Fig. 12 is a sectional view showing a jelly roll type electrode assembly 90 in which the electrode 45 of the second example is applied to the first electrode (the positive electrode) and the second electrode (the negative electrode) along the Y-axis direction (winding axis direction).

[0466] With reference to Fig. 12, the first uncoated portion 43a includes a first portion B1 adjacent to the core of the electrode assembly 90, a second portion B3 adjacent to the outer periphery of the electrode assembly 90, and a third portion B2 disposed between the first portion B1 and the second portion B3.

[0467] The height of the second portion B3 is relatively smaller than the height of the third portion B2 and decreases gradually or stepwise from the core to the outer periphery. Accordingly, an internal short circuit can be prevented from occurring because the bead portion and the second portion B3 touch each other while the bead portion of the battery case is pressed near the second portion B3.

[0468] The second uncoated portion 43b has the same structure as the first uncoated portion 43a. In a modification, the second uncoated portion 43b may have a conventional electrode structure or an electrode structure of other examples (modifications).

[0469] The ends 91 of the first uncoated portion 43a and the second uncoated portion 43b may be bent in the radial direction of the electrode assembly 90, for example, from the outer periphery to the core. At this time, the outermost portion 92 of the second portion B3 may not be significantly bent.

[0470] Fig. 13 is a sectional view showing a jelly roll type electrode assembly 100 in which any one of the electrodes 50, 60, 70 of the third to fifth examples (modifications thereof) is applied to the first electrode (the positive electrode) and the second electrode (the negative electrode) along the Y-axis direction (winding axis direction).

[0471] With reference to Fig. 13, the first uncoated portion 43a includes a first portion B1 adjacent to the core of the electrode assembly 100, a second portion B3 adjacent to the outer periphery of the electrode assembly 100, and a third portion B2 disposed between the first portion B1 and the second portion B3.

[0472] The height of the first section B1 is relatively smaller than the height of the third section B2. In addition, the bending length of the uncoated section 43a, located at the innermost side of the third section B2, is less than or equal to the radial length (R) of the first section B1. The bending length (H) corresponds to the distance from the bending point of the uncoated section 43a to the top of the uncoated section 43a. In a modified example, the bending length (H) may be less than the sum of the radial length (R) of the first section B1 and 10% of the radius of the core 102.

[0473] Therefore, the core 102 of the electrode assembly 100 is open to the outside by 90% or more of the diameter of the core 102, even if the third portion B2 is bent. The core 102 is a hollow space in the center of the electrode assembly 100. When the core 102 is not blocked, there is no difficulty in the electrolyte injection process, and the electrolyte injection efficiency is improved. In addition, by inserting a welding jig through the core 102, the welding process can be easily performed between the negative electrode current collector (or the positive electrode) and the battery case (or the terminal).

[0474] The height of the second portion B3 is relatively smaller than the height of the third portion B2. Accordingly, the bead portion and the second portion B3 can be prevented from contacting each other while the bead portion of the battery case near the second portion B3 is pressed to cause an internal short circuit.

[0475] In a modification, the height of the second section B3 may be reduced gradually or stepwise, unlike in Fig. 13. Also in Fig. 13, although the height of the third portion B2 is partially the same in a circumferential direction, the height of the third portion B2 may gradually or stepwise increase from the boundary between the first portion B1 and the third portion B2 to the boundary between the third portion B2 and the second portion B3. When the third portion B2 is divided into a plurality of segments, a region in which the height of the uncoated portion 43a changes corresponds to the height-variable region (② in Fig. 10a) of the segment.

[0476] The second uncoated portion 43b has the same structure as the first uncoated portion 43a. In a modification, the second uncoated portion 43b may have a conventional electrode structure or an electrode structure of other examples (modifications).

[0477] The ends 101 of the first uncoated portion 43a and the second uncoated portion 43b can be bent in the radial direction of the electrode assembly 100, for example, from the outer periphery to the core. At this time, the first portion B1 and the second portion B3 are not significantly bent.

[0478] When the third portion B2 includes a plurality of segments, the bending stress can be relieved to prevent the uncoated portion 43a from being torn or abnormally deformed near the bending point. In addition, when the width and / or height and / or separation distance of the segment are adjusted according to the numerical range of the above example, the segments are bent toward the core and overlapped in multiple layers to sufficiently ensure the welding strength, and an empty hole (gap) is not formed in the bent surface area.

[0479] Fig. 14 is a sectional view showing an electrode assembly 110 according to still another example along the Y-axis direction (winding axis direction).

[0480] With reference to Fig. 14, the electrode assembly 110 is essentially the same as the electrode assembly 100 of Fig. 13, except that the height of the second section B3 is substantially the same as the height of the outermost side of the third section B2.

[0481] The second section B3 may include a plurality of segments. The configuration of the plurality of segments is substantially the same as described in the fourth and fifth examples (modifications) with respect to electrodes.

[0482] In the electrode assembly 110, the height of the first portion B1 is relatively smaller than the height of the third portion B2. In addition, the bending length (H) of the uncoated portion located at the innermost side of the third portion B2 is less than or equal to the radial length (R) of the first portion B1. For example, the first portion B1 may be the segment skip region that does not have a segment (① in Fig. 10a). In a modified example, the bending length (H) may be less than the sum of the radial length (R) of the first section B1 and 10% of the radius of the core 102.

[0483] Therefore, the core 112 of the electrode assembly 110 is open to the outside by at least 90% or more of the diameter of the core 112, even if the third portion B2 is bent. When the core 112 is not blocked, there is no difficulty in the electrolyte injection process, and the electrolyte injection efficiency is improved. Furthermore, by inserting a welding jig through the core 112, the welding process can be easily performed between the negative electrode current collector (or the positive electrode) and the battery case (or terminal).

[0484] In a modification, the structure in which the height of the third portion B2 gradually or stepwise increases from the core to the outer periphery may be extended to the second portion B3. In this case, the height of the uncoated portion 43a may gradually or stepwise increase from the boundary between the first portion B1 and the third portion B2 to the outermost surface of the electrode assembly 110.

[0485] The second uncoated portion 43b has the same structure as the first uncoated portion 43a. In a modification, the second uncoated portion 43b may have a conventional electrode structure or an electrode structure of other examples (modifications).

[0486] The ends 111 of the first uncoated portion 43a and the second uncoated portion 43b can be bent in the radial direction of the electrode assembly 110, for example, from the outer circumference toward the core. At this time, the first portion B1 is not significantly bent.

[0487] When the third section B2 and the second section B3 include a plurality of segments, the bending stress can be relieved to prevent the uncoated sections 43a, 43b from being torn or abnormally deformed near the bending point. In addition, when the width and / or height and / or separation distance of the segment are adjusted according to the numerical range of the above example, the segments are bent toward the core and overlapped in multiple layers to sufficiently ensure the welding strength, and an empty hole (gap) is not formed in the bent surface area.

[0488] Fig. 15 is a sectional view showing an electrode assembly 120 according to still another example along the Y-axis direction (winding axis direction).

[0489] With reference to Fig. 15, the electrode assembly 120 is essentially the same as the electrode assembly 100 of Fig. 13, except that the height of the third section B2 has a pattern that increases and then gradually or stepwise decreases. The radial region in which the height of the third section B2 changes can be referred to as the height-variable region (② in Fig. 10a) of the segment. Even in this case, the height-variable region of the segment can be designed such that the uniform overlap layer number region, in which the number of overlapping layers of segments is 10 or more, appears in the above-described preferred numerical range in the bending surface region F formed by bending the third section B2.

[0490] This change in the height of the third section B2 can be achieved by using the step pattern (see Fig. 6) or adjusting the height of segments (see Fig. 7a or Fig. 8a), which are contained in the third section B2, are implemented.

[0491] In the electrode assembly 120, the height of the first portion B1 is relatively smaller than the height of the third portion B2. In addition, the bending length (H) of the uncoated portion located at the innermost side of the third portion B2 is less than or equal to the radial length (R) of the first portion B1. The area corresponding to the first portion B1 corresponds to the segment skip area, which does not have a segment (① in Fig. 10a). In a modified example, the bending length (H) may be less than the sum of the radial length (R) of the first section B1 and 10% of the radius of the core 102.

[0492] Therefore, the core 122 of the electrode assembly 120 is open to the outside by at least 90% or more of its diameter, even if the third portion B2 is bent toward the core. When the core 122 is not blocked, the electrolyte injection process is not difficult, and the electrolyte injection efficiency is improved. Furthermore, by inserting a welding jig through the core 122, the welding process can be easily performed between the negative electrode current collector (or the positive electrode) and the battery case (or terminal).

[0493] Furthermore, the height of the second portion B3 is relatively smaller than the height of the third portion B2, and preferably, no segment may be formed in the second portion B3. Accordingly, an internal short circuit can be prevented from occurring because the bead portion and the second portion B3 contact each other while the bead portion of the battery case is pressed near the second portion B3. In a modification, the height of the second portion B3 may decrease gradually or stepwise toward the outer periphery.

[0494] The second uncoated portion 43b has the same structure as the first uncoated portion 43a. In a modification, the second uncoated portion 43b may have a conventional electrode structure or an electrode structure of other examples (modifications).

[0495] The ends 121 of the first uncoated portion 43a and the second uncoated portion 43b can be bent from the outer periphery of the electrode assembly 120 toward the core. At this time, the first portion B1 and the second portion B3 are not significantly bent.

[0496] When the third portion B2 includes a plurality of segments, the bending stress can be relieved to prevent the uncoated portions 43a, 43b from being torn or abnormally deformed. In addition, when the width and / or height and / or separation distance of the segment are adjusted according to the numerical range of the above example, the segments are bent toward the core and overlapped in multiple layers to sufficiently ensure the welding strength, and an empty hole (gap) is not formed in the bent surface area.

[0497] Fig. 16 is a sectional view showing an electrode assembly 130 according to still another example along the Y-axis direction (winding axis direction).

[0498] With reference to Fig. 16, the electrode assembly 130 is substantially the same as the electrode assembly 120 of Fig. 15, except that the height of the second portion B3 has a pattern that gradually or stepwise decreases from the boundary point of the second portion B3 and the third portion B2 to the outermost surface of the electrode assembly 130.

[0499] This change in the height of the second section B3 can be achieved by extending the step pattern (see Fig. 6) contained in the third section B2 can be implemented on the second section B3, while at the same time the height of the pattern gradually or stepwise decreases toward the outer periphery. Additionally, in another modification, the change in the height of the second section B3 can be implemented by extending the segment structure of the third section B2 to the second section B3, while at the same time the height of the segments gradually or stepwise decreases toward the outer periphery.

[0500] In the electrode assembly 130, the height of the first section B1 is relatively smaller than the height of the third section B2. Furthermore, in the third section B2, the bending length (H) of the innermost uncoated section is less than or equal to the radial length (R) of the first section B1. The first section B1 corresponds to the segment skip region, which does not have a segment (① in Fig. 10a). In a modified example, the bending length (H) may be less than the sum of the radial length (R) of the first section B1 and 10% of the radius of the core 102.

[0501] Accordingly, the core 132 of the electrode assembly 130 is open to the outside by at least 90% or more of its diameter, even if the third portion B2 is bent toward the core. When the core 132 is not blocked, the electrolyte injection process is not difficult, and the electrolyte injection efficiency is improved. Furthermore, by inserting a welding jig through the core 132, the welding process can be easily performed between the negative electrode current collector (or the positive electrode) and the battery case (or terminal).

[0502] The second uncoated portion 43b has the same structure as the first uncoated portion 43a. In a modification, the second uncoated portion 43b may have a conventional electrode structure or an electrode structure of other examples (modifications).

[0503] The ends 131 of the first uncoated portion 43a and the second uncoated portion 43b can be bent from the outer periphery of the electrode assembly 130 toward the core. At this time, the first portion B1 is not significantly bent.

[0504] When the third section B2 and the second section B3 include a plurality of segments, the bending stress can be relieved to prevent the uncoated sections 43a, 43b from being torn or abnormally deformed near the bending point. In addition, when the width and / or height and / or separation distance of the segment are adjusted according to the numerical range of the example described above, the segments are bent toward the core and overlapped in multiple layers to sufficiently ensure the welding strength, and an empty hole (gap) is not formed in the bent surface area.

[0505] Meanwhile, in the previous examples (modified examples), the ends of the first uncoated portion 43a and the second uncoated portion 43b may be bent from the core toward the outer periphery. In this case, it is preferable that the second portion B3 be configured as the segment skip portion that does not have a segment (① in Fig. 10a) and is not bent toward the outer circumference. In addition, the width of the second portion B3 in the radial direction may be greater than or equal to the length in which the outermost uncoated portion (or segment) of the third portion B2 is bent. Only when the outermost uncoated portion (or segment) of the third portion B2 is bent toward the outer circumference, the end of the bent portion does not protrude toward the inner surface of the battery case beyond the outer circumference of the electrode assembly. Also, the change pattern of the segment structure may be opposite to the previous examples (modified examples). For example, the height of the segment may increase stepwise or gradually from the core to the outer circumference. That is, by arranging the segment skip region (① of Fig. 10a), the height-variable area (② of Fig. 10a) of the segment and the height-uniform area (③ of Fig. 10a) of the segment from the outer circumference of the electrode assembly to the core in the order, the uniform overlap layer number region in which the number of overlap layers of segments is 10 or more can appear in a desired numerical range in the bending surface region.

[0506] Various electrode assembly structures according to an example can be applied to a cylindrical battery.

[0507] For example, the cylindrical battery may be a cylindrical battery whose shape factor ratio (defined as a value obtained by dividing the diameter of the cylindrical battery by the height, namely a ratio of height (H) to diameter (Φ)) is greater than approximately 0.4. Here, the shape factor means a value indicating the diameter and height of a cylindrical battery.

[0508] For example, the cylindrical battery may have a diameter of 40 mm to 50 mm and a height of 60 mm to 130 mm. The form factor of the cylindrical battery according to an example may be, for example, 46110, 4875, 48110, 4880, or 4680. In the numerical value representing the form factor, the first two numbers indicate the diameter of the battery, and the remaining numbers indicate the height of the battery.

[0509] When an electrode assembly with a tabless structure is applied to a cylindrical battery with an aspect ratio of more than 0.4, the stress applied in the radial direction when the uncoated portion is bent is large, so the uncoated portion is easily torn. Furthermore, when welding the current collector to the bent surface area of ​​the uncoated portion, it is necessary to sufficiently increase the number of overlapping layers of the uncoated portion on the bent surface area to sufficiently secure the welding strength and reduce the resistance. This requirement can be achieved by the electrode and the electrode assembly according to the examples (modifications) of the present disclosure.

[0510] A battery according to an example may be a cylindrical battery having an approximately cylindrical shape, a diameter of approximately 46 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0511] A battery according to another example may be a cylindrical battery having a substantially cylindrical shape, a diameter of approximately 48 mm, a height of approximately 75 mm, and a form factor ratio of 0.640.

[0512] A battery according to yet another example may be a cylindrical battery having an approximately cylindrical shape, a diameter of approximately 48 mm, a height of approximately 110 mm, and a form factor ratio of 0.436.

[0513] A battery according to yet another example may be a cylindrical battery having an approximately cylindrical shape, a diameter of approximately 48 mm, a height of approximately 80 mm, and a form factor ratio of 0.600.

[0514] A battery according to yet another example may be a cylindrical battery having an approximately cylindrical shape, a diameter of approximately 46 mm, a height of approximately 80 mm, and a form factor ratio of 0.575.

[0515] Conventionally, batteries with a form factor ratio of approximately 0.4 or less were used. For example, 1865 batteries, 2170 batteries, etc. were conventionally used. The 1865 battery has a diameter of approximately 18 mm, a height of approximately 65 mm, and a form factor ratio of 0.277. The 2170 battery has a diameter of approximately 21 mm, a height of approximately 70 mm, and a form factor ratio of 0.300.

[0516] The cylindrical battery is described in detail below according to an example.

[0517] Fig. 17 is a sectional view showing a cylindrical battery 140 according to an example along the Y-axis direction.

[0518] With reference to Fig. 17, the cylindrical battery 140 according to one example includes an electrode assembly 141 having a first electrode, a separator, and a second electrode, a battery case 142 for accommodating the electrode assembly 141, and a sealing body 143 for sealing an open end of the battery case 142.

[0519] The battery case 142 is a cylindrical container with an opening at the top. The battery case 142 is formed from a conductive metal material, such as aluminum, steel, or stainless steel. A nickel plating layer may be formed on the surface of the battery case 142. The battery case 142 accommodates the electrode assembly 141 inside through the top opening and also accommodates the electrolyte.

[0520] The electrolyte can be a salt with a structure like A+B-. Here, A+ comprises an alkali metal cation, such as Li+, Na+, or K+, or a combination thereof. and B- comprises at least one anion selected from the group consisting of F-, Cl-, Br-, I-, NO3-, N(CN)2-, BF4-, Cl4-, Alo4-, Alcl4-, PF6-, Sbf6-, Asf6-, BF2C2O4-, BC4O8-, (CF3)2PF4-, (CF3)3PF3-, (CF3)4PF2-, (CF3)5PF-, (CF3)6P-, CF3SO3-, C4F9SO3-, CF3CF2SO3-, (CF3)2N-, (FSO2)2N-, CF3CF2 (CF3)2CO-, (CF3)2SO2CH-, (SF5)C-, (CF3)3C-, CF3SO3-, (CF3)7SO3-, CF3CO-, CH2CO-, SCN3- and (CF3)2SO2N-.

[0521] The electrolyte can also be dissolved in an organic solvent. The organic solvent can be propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), γ-butyrolactone, or a mixture thereof.

[0522] The electrode assembly 141 may have a jelly-roll shape, but the present invention is not limited thereto. The electrode assembly 141 may be manufactured by winding a laminate formed by sequentially laminating a lower separator, a first electrode, an upper separator, and a second electrode at least once based on the winding axis of the core C, as shown in Fig. 2 shown.

[0523] The first electrode and the second electrode have different polarities. That is, when one has positive polarity, the other has negative polarity. At least one of the first electrode and the second electrode may have an electrode structure according to the above examples (modifications). Furthermore, the other of the first electrode and the second electrode may have a conventional electrode structure or an electrode structure according to examples (modifications). The pair of electrodes included in the electrode assembly 141 is not limited to one pair; two or more pairs may be included.

[0524] A first uncoated portion 146a of the first electrode and a second uncoated portion 146b of the second electrode protrude from the upper and lower portions of the electrode assembly 141, respectively. The first electrode has the electrode structure of the first example (modification). Accordingly, in the first uncoated portion 146a, the height of the second portion B3 is smaller than the height of the uncoated portion of the other region. The second portion B3 is spaced from the inner periphery of the battery case 142, particularly the bead portion 147, by a predetermined distance. Therefore, the second portion B3 of the first electrode does not come into contact with the battery case 142, which is electrically connected to the second electrode, thereby preventing an internal short circuit of the battery 140.

[0525] The second uncoated portion 146b of the second electrode may have the same structure as the first uncoated portion 146a. In another modification, the second uncoated portion 146b may optionally have the structure of the uncoated portion of the electrode according to examples (modifications).

[0526] The sealing body 143 may include a cap 143a having a plate shape, a first gasket 143b for providing airtightness between the cap 143a and the battery case 142 and having insulating property, and a connecting plate 143c electrically and mechanically coupled to the cap 143a.

[0527] The cap 143a is a component made of a conductive metal material and covers the top opening of the battery case 142. The cap 143a is electrically connected to the uncoated portion 146a of the first electrode and is electrically insulated from the battery case 142 by the first seal 143b. Accordingly, the cap 143a can function as a first electrode terminal (e.g., the positive electrode) of the cylindrical battery 140.

[0528] The cap 143a is placed on the bead portion 147 formed on the battery case 142 and is secured by a crimp portion 148. The first gasket 143b may be disposed between the cap 143a and the crimp portion 148 to ensure the airtightness of the battery case 142 and the electrical insulation between the battery case 142 and the cap 143a. The cap 143a may have a protrusion 143d projecting upward from the center thereof.

[0529] The battery housing 142 is electrically connected to the second uncoated portion 146b of the second electrode. Therefore, the battery housing 142 has the same polarity as the second electrode. If the second electrode has negative polarity, the battery housing 142 also has negative polarity.

[0530] The battery case 142 has the bead portion 147 and the crimp portion 148 at the top thereof. The bead portion 147 is formed by press-fitting the periphery of the outer periphery of the battery case 142. The bead portion 147 prevents the electrode assembly 141 housed in the battery case 142 from leaking through the top opening of the battery case 142 and can function as a support portion on which the sealing body 143 is placed.

[0531] The inner periphery of the bead portion 147 is spaced from the second portion B3 of the first electrode by a predetermined distance. Specifically, the lower end of the inner periphery of the bead portion 147 is spaced from the second portion B3 of the first electrode by a predetermined distance. Since the second portion B3 has a low height, the second portion B3 is not significantly affected even when the battery case 142 is press-fitted from the outside to form the bead portion 147. Accordingly, the second portion B3 is not compressed by other components such as the bead portion 147, and thus the shape of the electrode assembly 141 is prevented from being partially deformed, thereby preventing a short circuit in the cylindrical battery 140.

[0532] For example, if the indentation depth of the bead portion 147 is defined as D1 and the radial length from the inner periphery of the battery case 142 to the boundary point of the second portion B3 and the third portion B2 is defined as D2, the formula D1 ≤ D2 may be satisfied. In this case, damage to the second portion B3 is substantially prevented when the battery case 142 is press-fitted to form the bead portion 147.

[0533] The crimping portion 148 is formed on the bead portion 147. The crimping portion 148 has an extended and curved shape to cover the outer periphery of the cap 143a disposed on the bead portion 147 and a part of the upper surface of the cap 143a.

[0534] The cylindrical battery 140 may further include a first current collector 144 and / or a second current collector 145 and / or an insulator 146.

[0535] The first current collector 144 is coupled to the upper portion of the electrode assembly 141. The first current collector 144 is made of a conductive metal material, such as aluminum, copper, steel, and nickel, and is electrically connected to the uncoated portion 146a of the first electrode. The electrical connection may be made by welding. A lead 149 may be connected to the first current collector 144. The lead 149 may extend upward above the electrode assembly 141 and be coupled to the connecting plate 143c or be directly coupled to the lower surface of the cap 143a. The lead 149 may be connected to other components by welding.

[0536] For example, the first current collector 144 may be formed integrally with the conduit 149. In this case, the conduit 149 may have an elongated plate shape extending outward from near the center of the first current collector 144.

[0537] The first current collector 144 may have a plurality of asperities (not shown) formed radially on a lower surface thereof. When the radial asperity is provided, the asperity may be pressed into the first uncoated portion 146a of the first electrode by pressing the first current collector 144.

[0538] The first current collector 144 is coupled to the end of the first uncoated portion 146a. The first uncoated portion 146a and the first current collector 144 can be coupled, for example, by laser welding. The laser welding can be performed in such a way that a base material of the current collector 144 partially melts. In a modification, the first current collector 144 and the first uncoated portion 146a can be welded in a state where a solder is interposed therebetween. In this case, the solder can have a lower melting point compared to the first current collector 144 and the first uncoated portion 146a. The laser welding can be replaced by resistance welding, ultrasonic welding, spot welding, or the like.

[0539] The second current collector 145 may be coupled to the bottom surface of the electrode assembly 141. One side of the second current collector 145 may be coupled to the second uncoated portion 146b by welding, and the other side may be coupled to the inner bottom surface of the battery case 142 by welding. The coupling structure between the second current collector 145 and the second uncoated portion 146b may be substantially the same as the coupling structure between the first current collector 144 and the first uncoated portion 146a.

[0540] The uncoated portions 146a, 146b are not limited to the illustrated structure. Accordingly, the uncoated portions 146a, 146b can selectively adopt not only a conventional uncoated portion structure but also the uncoated portion structure of the electrode according to examples (modifications).

[0541] The insulator 146 may cover the first current collector 144. The insulator 146 may cover the first current collector 144 at the upper surface of the first current collector 144, thereby preventing direct contact between the first current collector 144 and the inner periphery of the battery case 142.

[0542] The insulator 146 has a lead hole 151 so that the lead 149 extending upward from the first current collector 144 can be pulled out therethrough. The lead 149 is pulled upward through the lead hole 151 and coupled to the lower surface of the connecting plate 143c or the lower surface of the cap 143a.

[0543] A peripheral portion of the edge of the insulator 146 may be disposed between the first current collector 144 and the bead portion 147 to secure the coupled body of the electrode assembly 141 and the first current collector 144. Accordingly, in the coupled body of the electrode assembly 141 and the first current collector 144, the movement of the battery 140 in the winding axis direction Y can be restricted, thereby improving the assembly stability of the battery 140.

[0544] The insulator 146 may be made of an insulating polymer resin. In one example, the insulator 146 may be made of polyethylene, polypropylene, polyimide, or polybutylene terephthalate.

[0545] The battery case 142 may further include a vent portion 152 formed on a lower surface thereof. The vent portion 152 corresponds to a region having a smaller thickness compared to the peripheral region of the lower surface of the battery case 142. The vent portion 152 is structurally weak compared to the surrounding region. Accordingly, when an abnormality occurs in the cylindrical battery 140 and the internal pressure increases to a predetermined level or more, the vent portion 152 may be ruptured, so that the gas generated inside the battery case 142 is discharged to the outside. The internal pressure at which the vent portion 152 ruptures may be approximately 15 kgf / cm 2 up to 35 kgf / cm 2 be.

[0546] The vent portion 152 may be formed continuously or discontinuously, while drawing a circle on the bottom surface of the battery case 142. In a modification, the vent portion 152 may be formed in a straight pattern or other patterns.

[0547] Fig. 18 is a sectional view showing a cylindrical battery 150 according to another example along the Y-axis direction.

[0548] With reference to Fig. 18, the cylindrical battery 150 is essentially the same as the cylindrical battery 140 of Fig. 17, except that the electrode structure of the second example (modification) is employed in the first uncoated portion 146a of the first electrode.

[0549] With reference to Fig. 18, the first uncoated portion 146a of the first electrode may have a shape in which the height of the second portion B3 gradually or stepwise decreases toward the inner periphery of the battery case 142. For example, the virtual line connecting the upper end of the second portion B3 may have the same or a similar shape to the inner periphery of the bead portion 147.

[0550] The second portion B3 forms an inclined surface. Accordingly, when the battery case 142 is press-fitted to form the bead portion 147, the second portion B3 can be prevented from being compressed and damaged by the bead portion 147. In addition, it is possible to suppress the phenomenon of the second portion B3 coming into contact with the battery case 142 with a different polarity to cause an internal short circuit.

[0551] The remaining components of the cylindrical battery 150 are substantially the same as the example (modification) described above.

[0552] The uncoated portions 146a, 146b are not limited to the illustrated structure. Accordingly, the uncoated portions 146a, 146b may selectively include not only a conventional uncoated portion structure but also the uncoated portion structure of the electrode according to examples (modifications).

[0553] Fig. 19 is a sectional view showing a cylindrical battery 160 according to still another example along the Y-axis direction.

[0554] With reference to Fig. 19, the cylindrical battery 160 is substantially the same as the cylindrical batteries 140, 150 described above, except that the lead 149 connected to the first current collector 144 is directly connected to the cap 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 have a structure in close contact with the lower surface of the cap 143a.

[0555] In the cylindrical battery 160, the diameter of the first current collector 144 and the outermost diameter of the third portion B2 are smaller than the minimum inner diameter of the battery case 142. In addition, the diameter of the first current collector 144 may be greater than or equal to the outermost diameter of the third portion B2.

[0556] Specifically, the minimum inner diameter of the battery case 142 may be equal to the inner diameter of the battery case 142 at a position where the bead portion 147 is formed. At this time, the outermost diameter of the first current collector 144 and the third portion B2 is smaller than the inner diameter of the battery case 142 at the position where the bead portion 147 is formed. Furthermore, the diameter of the first current collector 144 may be greater than or equal to the outermost diameter of the third portion B2. The peripheral portion of the edge of the insulator 146 may be arranged between the second portion B3 and the bead portion 147 in a downwardly bent state to fix the coupled body of the electrode assembly 141 and the first current collector 144.

[0557] For example, the insulator 146 may include a portion covering the second portion B3 and a portion covering the first current collector 144, and a portion connecting these two portions may have a curved shape corresponding to the curved shape of the bead portion 147. The insulator 146 may insulate the second portion B3 and the inner periphery of the bead portion 147, while simultaneously insulating the first current collector 144 and the inner periphery of the bead portion 147.

[0558] The first current collector 144 may be positioned higher than the lower end of the bead portion 147 and may be coupled to the first portion B1 and the third portion B2. At this time, the indentation depth D1 of the bead portion 147 is less than or equal to the distance D2 from the inner periphery of the battery case 142 to the boundary between the second portion B3 and the third portion B2. Accordingly, the first portion B1, the third portion B2, and the first current collector 144 coupled thereto may be positioned higher than the lower end of the bead portion 147. The lower end of the bead portion 147 represents a bending point (B) between the portion of the battery case 142 in which the electrode assembly 141 is housed and the bead portion 147.

[0559] Since the first portion B1 and the third portion B2 occupy the inner space of the bead portion 147 in the radial direction, the empty space between the electrode assembly 141 and the cap 143a can be minimized. In addition, the connecting plate 143c located in the empty space between the electrode assembly 141 and the cap 143a is eliminated. Accordingly, the lead 149 of the first current collector 144 can be directly coupled to the bottom surface of the cap 143a. According to the above structure, the empty space in the battery can be reduced, and the energy density can be maximized accordingly to the reduction of the empty space.

[0560] In the cylindrical battery 160, the first current collector 144 and the second current collector 145 can be welded to the ends of the first and second uncoated portions 146a, 146b, respectively, in the same manner as in the above example.

[0561] The uncoated portions 146a, 146b are not limited to the illustrated structure. Accordingly, the uncoated portions 146a, 146b may selectively include not only a conventional uncoated portion structure but also the uncoated portion structure of the electrode according to examples (modifications).

[0562] Fig. 20 is a sectional view showing a cylindrical battery 170 according to still another example along the Y-axis.

[0563] According to Fig. 20, the structure of the electrode assembly of the cylindrical battery 170 is substantially the same as that of the cylindrical battery 140 of Fig. 17, and the other structure except the electrode assembly is changed.

[0564] Specifically, the cylindrical battery 170 includes a battery case 171 through which a terminal 172 is installed. The terminal 172 is installed through a perforation hole formed in the closed surface (the upper surface in the drawing) of the battery case 171. The terminal 172 is riveted to the perforation hole of the battery case 171 in a state where a second gasket 173 made of an insulating material is interposed. The terminal 172 is exposed to the outside in a direction opposite to the direction of gravity.

[0565] The terminal 172 has a terminal exposure portion 172a and a terminal insertion portion 172b. The terminal exposure portion 172a is exposed to the outside of the closed surface of the battery case 171. The terminal exposure portion 172a may be located approximately at a center portion of the closed surface of the battery case 171. The maximum diameter of the terminal exposure portion 172a may be larger than the maximum diameter of the perforation hole formed in the battery case 171. The terminal insertion portion 172b may be electrically connected to the uncoated portion 146a of the first electrode through approximately the center portion of the closed surface of the battery case 171. The bottom edge of the terminal insertion portion 172b may be riveted to the inner surface of the battery case 171.That is, the bottom edge of the terminal insertion portion 172b may have a shape curved toward the inner surface of the battery case 171. A flat portion 172c is included within the bottom edge of the terminal insertion portion 172b. The maximum diameter of the riveted lower portion of the terminal insertion portion 172b may be larger than the maximum diameter of the perforation hole of the battery case 171.

[0566] The flat portion 172c of the terminal insertion portion 172b may be welded to the center of the first current collector 144, which is connected to the first uncoated portion 146a of the first electrode. Laser welding is preferred as the welding method, but other welding methods, such as ultrasonic welding, may be used.

[0567] An insulator 174 made of an insulating material may be disposed between the first current collector 144 and the inner surface of the battery case 171. The insulator 174 covers the upper portion of the first current collector 144 and the upper edge of the electrode assembly 141. Accordingly, it is possible to prevent the second portion B3 of the electrode assembly 141 from contacting the inner surface of the battery case 171 with a different polarity and causing a short circuit.

[0568] The thickness of the insulator 174 is equal to or slightly greater than the distance between the upper surface of the first current collector 144 and the inner surface of the closed portion of the battery case 171. Accordingly, the insulator 174 can be in contact with the upper surface of the first current collector 144 and the inner surface of the closed portion of the battery case 171.

[0569] The terminal insertion portion 172b of the terminal 172 may be welded to the first current collector 144 through the perforation hole of the insulator 174. The diameter of the perforation hole formed in the insulator 174 may be larger than the diameter of the rivet portion at the lower end of the terminal insertion portion 172b. For example, the perforation hole may expose the lower portion of the terminal insertion portion 172b and the second gasket 173.

[0570] The second seal 173 is disposed between the battery case 171 and the terminal 172 to prevent the battery case 171 and the terminal 172 from electrically contacting each other with opposite polarities. Accordingly, the upper surface of the battery case 171, having a roughly flat shape, can function as a second electrode terminal (e.g., the negative electrode) of the cylindrical battery 170.

[0571] The second gasket 173 includes a gasket exposure portion 173a and a gasket insertion portion 173b. The gasket exposure portion 173a is disposed between the terminal exposure portion 172a of the terminal 172 and the battery case 171. The gasket insertion portion 173b is disposed between the terminal insertion portion 172b of the terminal 172 and the battery case 171. The gasket insertion portion 173b can be deformed together when the terminal insertion portion 172b is riveted to be in close contact with the inner surface of the battery case 171. The second gasket 173 can be made of, for example, a polymer resin with insulation.

[0572] The seal exposure portion 173a of the second seal 173 may have an expanded shape to cover the outer periphery of the terminal exposure portion 172a of the terminal 172. When the second seal 173 covers the outer periphery of the terminal 172, it is possible to prevent a short circuit from occurring while an electrical connection part, such as a bus bar, is coupled to the upper surface of the battery case 171 and / or the terminal 172. Although not shown in the drawings, the seal exposure portion 173a may have an expanded shape to cover not only the outer peripheral surface of the terminal exposure portion 172a but also part of the upper surface thereof.

[0573] When the second gasket 173 is made of a polymer resin, the second gasket 173 may be coupled to the battery case 171 and the terminal 172 by thermofusion. In this case, the airtightness can be improved at the coupling interface between the second gasket 173 and the terminal 172 and at the coupling interface between the second gasket 173 and the battery case 171. Meanwhile, when the gasket exposure portion 173a of the second gasket 173 has a shape extending toward the upper surface of the terminal exposure portion 172a, the terminal 172 may be integrally coupled to the second gasket 173 by insert molding.

[0574] In the upper surface of the battery case 171, a remaining area 175, different from the area occupied by the terminal 172 and the second seal 173, corresponds to the second electrode terminal having a polarity opposite to that of the terminal 172.

[0575] The second current collector 176 is coupled to the lower portion of the electrode assembly 141. The second current collector 176 is made of a conductive metal material, such as aluminum, steel, copper, or nickel, and is electrically connected to the second uncoated portion 146b of the second electrode.

[0576] For example, the second current collector 176 is electrically connected to the battery case 171. For this purpose, at least a portion of the edge of the second current collector 176 may be arranged and fixed between the inner surface of the battery case 171 and a first gasket 178b. In one example, at least a portion of the edge of the second current collector 176 may be fixed to the bead portion 180 by welding in a state where it is supported on the bottom surface of the bead portion 180 formed at the bottom of the battery case 171. In a modification, at least a portion of the edge of the second current collector 176 may be welded directly to the inner wall surface of the battery case 171.

[0577] The second current collector 176 may have a plurality of asperities (not shown) formed radially on a surface facing the second uncoated portion 146b. Once the asperity is formed, the asperity may be pressed into the second uncoated portion 146b by pressing the second current collector 176.

[0578] For example, the second current collector 176 and the ends of the second uncoated portion 146b may be coupled by welding, for example, laser welding. Furthermore, the welded portions of the second current collector 176 and the second uncoated portion 146b may be spaced apart from the core C by a predetermined distance based on the inner circumference of the bead portion 180.

[0579] A sealing body 178 for sealing the lower open end of the battery case 171 includes a cap 178a having a plate shape and a first gasket 178b. The first gasket 178b electrically separates the cap 178a and the battery case 171. A crimping portion 181 holds the edge of the cap 178a and the first gasket 178b together. The cap 178a includes a venting portion 179. The configuration of the venting portion 179 is substantially the same as in the above example (modification). The lower surface of the cap 178a may be positioned higher than the lower end of the crimping portion 181. In this case, a space is formed under the cap 178a, ensuring smooth venting. This is particularly useful when the cylindrical battery 170 is installed with the crimping portion 181 facing the direction of gravity.

[0580] For example, the cap 178a is made of a conductive metal material. However, since the first seal 178b is disposed between the cap 178a and the battery case 171, the cap 178a has no electrical polarity. The seal body 178 primarily seals the open end of the lower portion of the battery case 171 and functions to discharge gas when the internal pressure of the battery 170 increases above a critical value. The critical internal pressure value is 15 kgf / cm 2 up to 35 kgf / cm 2 .

[0581] For example, the terminal 172 electrically connected to the first uncoated portion 146a of the first electrode is used as the first electrode terminal. In addition, in the upper surface of the battery case 171 electrically connected to the second uncoated portion 146b of the second electrode through the second current collector 176, a part 175 other than the terminal 172 having a different polarity than the first electrode terminal is used as the second electrode terminal. When two electrode terminals are located at the upper portion of the cylindrical battery 170 as above, it is possible to dispose electrical connection components such as bus bars on only one side of the cylindrical battery 170. This can simplify the battery pack structure and improve energy density.In addition, since the portion 175 used as the second electrode terminal has a roughly flat shape, a sufficient connection area can be ensured for connecting electrical connection components such as busbars. Accordingly, the cylindrical battery 170 can reduce the resistance at the connection portion of the electrical connection components to a desired level.

[0582] Meanwhile, the structure of the uncoated portion and the structure of the electrode assembly 141 are not limited to those shown in the drawings and can be replaced by the structures of the above examples (modifications).

[0583] Fig. 21 is a sectional view showing a cylindrical battery 180 according to still another example along the Y-axis.

[0584] With reference to Fig. 21, the structure of the electrode assembly 141 of the cylindrical battery 180 is substantially the same as that of the Fig. 18, and the components other than the electrode assembly 141 are substantially the same as those shown in Fig. 20 shown cylindrical battery 170.

[0585] Accordingly, the configuration of the example (modification) with respect to the cylindrical batteries 150, 170 can be equally applied to the cylindrical battery 180.

[0586] In addition, the structure of the electrode assembly 141 and the structure of the uncoated portion are not limited to those shown in the drawing and can be replaced by the structures of the above examples (modifications).

[0587] Fig. 22 is a sectional view showing a cylindrical battery 190 according to still another example along the Y-axis.

[0588] With reference to Fig. 22 contains the cylindrical battery 190 which in Fig. 14, and the components other than the electrode assembly 110 are substantially the same as those shown in Fig. 17 illustrated cylindrical battery 140. Accordingly, the battery 140 illustrated with reference to Fig. 14 and Fig. The configuration described in section 17 can be applied to this example in essentially the same way.

[0589] With reference to the Fig. 10a and Fig. 22, the first and second uncoated portions 146a, 146b of the electrode assembly 110 are bent in the radial direction of the electrode assembly 110, for example, from the outer circumference to the core, to form a bending surface area F.

[0590] The first section B1 has a lower height than the other sections and corresponds to the segment skip area a1, which has no segment, so that it is not bent towards the core.

[0591] For example, the bending surface area F may include a segment skip area a1, a height-variable area a2 of the segment, and a height-uniform area a3 of the segment from the core to the outer circumference.

[0592] As in the Fig. 10c, Fig. 10d and Fig. As shown in Fig. 10e, the bending surface region F includes a region b1 with a uniform number of overlapping layers besides the segment skipping region a1 in which the number of overlapping layers of segments is 10 or more.

[0593] The bending surface area F may also include a region b2 with a decreasing number of overlap layers adjacent to the outer circumference of the electrode assembly 110, in which the number of overlap layers gradually decreases from segment to segment toward the outer circumference. For example, the region b1 with a uniform number of overlap layers may be set as the welding target area.

[0594] In the bending surface area F, the preferred numerical ranges of the ratio (a2 / c), which is a ratio of the height-variable area a2 to the segment-containing radius area c, the ratio (b1 / c) of the area b1 with a uniform number of overlap layers to the segment-containing radius area c, and the ratio of the area of ​​the area b1 with a uniform number of overlap layers to the area of ​​the bending surface area F have already been described above and will therefore not be described again.

[0595] The first current collector 144 may be laser welded to the bending surface area F of the first uncoated portion 146a, and the second current collector 145 may be laser welded to the bending surface area F of the second uncoated portion 146b. The welding method may be replaced by ultrasonic welding, resistance welding, spot welding, or the like.

[0596] For example, 50% or more of the welding area W of the first current collector 144 and the second current collector 145 may overlap the uniform overlap layer number b1 region of the bending surface area F. Optionally, the remaining area of ​​the welding area W may overlap the decreasing overlap layer number b2 region of the bending surface area F. In view of high welding strength, low welding interface resistance, and preventing damage to the separator or the active material layer, it is further preferable that the entire welding area W overlap the uniform overlap layer number b1 region.

[0597] For example, in the area b1 with a uniform number of overlap layers overlapping the welding area W and optionally the area b2 with a decreasing number of overlap layers, the number of overlapping layers of segments can be 10 to 35.

[0598] Optionally, when the number of overlapping segment layers in the decreasing overlap layer number region b2 overlapping the welding region W is less than 10, the laser power for welding the decreasing overlap layer number region b2 can be reduced below that of the uniform overlap layer number region b1. That is, when the welding region W simultaneously overlaps the uniform overlap layer number region b1 and the decreasing overlap layer number region b2, the laser power can be varied according to the number of overlapping segment layers. In this case, the welding strength of the uniform overlap layer number region b1 can be greater than the welding strength of the decreasing overlap layer number region b2.

[0599] In the bending surface region F formed at the upper and lower portions of the electrode assembly 110, the radial length of the segment skipping region a1 and / or the segment height variable region a2 and / or the segment height uniform region a3 may be the same as or different from each other.

[0600] In the electrode assembly 110, the height of the first section B1 is relatively smaller than that of the other sections. In addition, as shown in Fig. 14, the bending length (H) of the uncoated portion located at the innermost side of the third portion B2 is smaller than a value obtained by adding the radial length (R) of the first portion B1 and 10% of the radius of the core 112.

[0601] Accordingly, the core 112 of the electrode assembly 110 can be opened outward by at least 90% or more of its diameter, even if the first uncoated portion 146a is bent toward the core. When the core 112 is not blocked, there is no difficulty in the electrolyte injection process, and the electrolyte injection efficiency is improved. Furthermore, by inserting a welding jig through the core 112, the welding process between the second current collector 145 and the battery case 142 can be easily performed.

[0602] When the uncoated portions 146a, 146b have a segment structure, if the width and / or height and / or separation distance of the segments are adjusted to meet the numerical ranges of the above example, the segments overlap in multiple layers to sufficiently secure the welding strength when the segments are bent, and an empty space (gap) is not formed in the bent surface area F.

[0603] For example, the first current collector 144 and the second current collector 145 may have an outer diameter that encloses the ends of the segments 61, 61' (see Fig. 10f) that are bent in the last winding turn of the uniform-height region a3 of the first electrode and the second electrode. In this case, welding can be performed in a state where the segments constituting the bending surface region F are uniformly pressed by the current collector, and the densely stacked state of the segments can be well maintained even after welding. The densely stacked state means a state where there are essentially no gaps between the segments, as shown in Fig. 10a. The densely stacked state helps reduce the resistance of the cylindrical battery 190 to a level suitable for rapid charging (e.g., 4 milliohms) or below. The resistance may be at least 0.5 mΩ, or at least 1.0 mΩ, and / or 3.8 mΩ or less, 3.5 mΩ or less, or 3 mΩ or less.

[0604] The structures of the uncoated portions 146a, 146b can be changed to the structures according to the above examples (modifications). Furthermore, a conventional uncoated portion structure can be applied to any of the uncoated portions 146a, 146b without limitation.

[0605] Fig. 23 is a sectional view showing a cylindrical battery 200 according to still another example along the Y-axis.

[0606] With reference to Fig. 23 includes the cylindrical battery 200 which is Fig. 14, and the components other than the electrode assembly 110 are substantially the same as those of the electrode assembly 110 shown in Fig. 21 illustrated cylindrical battery 180. Accordingly, the battery 180 illustrated with reference to Fig. 14 and Fig. The configuration described in section 21 can be applied to this example in essentially the same way.

[0607] With reference to the Fig. 10a and Fig. 23, the first and second uncoated portions 146a, 146b of the electrode assembly 110 are bent in the radial direction of the electrode assembly 110, for example, from the outer circumference toward the core, to form a bending surface area F.

[0608] The first section B1 has a lower height than the other sections and corresponds to the segment skip area a1, which has one segment so that it is not bent towards the core.

[0609] For example, the bending surface area F may include a segment skip area a1, a height-variable area a2 of the segment, and a height-uniform area a3 of the segment from the core to the outer circumference.

[0610] As in the Fig. 10c, Fig. 10d and Fig. As shown in Fig. 10e, the bending surface region F includes a region b1 with a uniform number of overlapping layers besides the segment skipping region a1 in which the number of overlapping layers of segments is 10 or more.

[0611] The bending surface area F may also include a region b2 with a decreasing number of overlap layers adjacent to the outer circumference of the electrode assembly 110, in which the number of overlapping layers of segments decreases toward the outer circumference. For example, the region b1 with a uniform number of overlap layers may be set as the welding target area.

[0612] In the bending surface area F, the preferred numerical ranges of the ratio (a2 / c), which is a ratio of the height-variable area a2 to a radius area c including segments, the ratio (b1 / c) of the area b1 with a uniform number of overlap layers to the radius area c including segments, and the ratio of the area of ​​the area b1 with a uniform number of overlap layers to the area of ​​the bending surface area F have already been described above and will therefore not be described again.

[0613] The first current collector 144 may be laser welded to the bending surface area F of the first uncoated portion 146a, and the second current collector 176 may be laser welded to the bending surface area F of the second uncoated portion 146b. The welding method may be replaced by ultrasonic welding, resistance welding, spot welding, or the like. The welding area W of the second current collector 176 and the second uncoated portion 146b may be spaced from the inner surface of the bead portion 180 by a predetermined distance.

[0614] For example, 50% or more of the welding area W of the first current collector 144 and the second current collector 176 may overlap the region with a uniform overlap layer number b1 of the bending surface region F. Optionally, the remaining area of ​​the welding area W may overlap the area with a decreasing overlap layer number b2 of the bending surface region F. In view of high welding strength, low welding interface resistance, and preventing damage to the separator or the active material layer, it is more preferable that the entire welding area W overlaps the region with a uniform overlap layer number b1.

[0615] For example, in the area b1 with a uniform number of overlap layers overlapping the welding area W and optionally the area b2 with a decreasing number of overlap layers, the number of overlapping layers of segments can be 10 to 35.

[0616] Optionally, when the number of overlapping segment layers in the decreasing overlap layer number region b2 overlapping the welding region W is less than 10, the laser power for welding the decreasing overlap layer number region b2 can be reduced below that of the uniform overlap layer number region b1. That is, when the welding region W simultaneously overlaps the uniform overlap layer number region b1 and the decreasing overlap layer number region b2, the laser power can be varied according to the number of overlapping segment layers. In this case, the welding strength of the uniform overlap layer number region b1 can be greater than the welding strength of the decreasing overlap layer number region b2.

[0617] In the bending surface region F formed at the upper and lower portions of the electrode assembly 110, the radial length of the segment skipping region a1 and / or the segment height variable region a2 and / or the segment height uniform region a3 may be the same as or different from each other.

[0618] In the electrode assembly 110, the height of the first section B1 is relatively smaller than that of the other sections. In addition, as shown in Fig. 14, the bending length (H) of the uncoated portion located at the innermost side of the third portion B2 is smaller than a value obtained by adding the radial length (R) of the first portion B1 and 10% of the radius of the core 112.

[0619] Therefore, the core 112 of the electrode assembly 110 can be opened outward by at least 90% or more of its diameter, even if the uncoated portion 146a is bent toward the core. When the core 112 is not blocked, there is no difficulty in the electrolyte injection process, and the electrolyte injection efficiency is improved. Furthermore, by inserting a welding jig through the core 112, the welding process between the first current collector 144 and the terminal 172 can be easily performed.

[0620] When the first and second uncoated portions 146a, 146b have a segment structure, if the width and / or height and / or separation distance of the segments are adjusted to satisfy the numerical ranges of the above example, the segments overlap in multiple layers to sufficiently secure the welding strength when the segments are bent, and an empty space (gap) is not formed in the bent surface area F.

[0621] For example, in the first current collector 144 and the second current collector 176, the areas that contact the first and second uncoated sections 146a, 146 may have an outer diameter that encloses the ends of the segments 61, 61' (see Fig. 10f) that are bent in the last winding turn of the uniform-height region a3 of the first electrode and the second electrode. In this case, welding can be performed in a state where the segments constituting the bending surface region F are uniformly pressed by the current collector, and the densely stacked state of the segments can be well maintained even after welding. The densely stacked state means a state where there are essentially no gaps between the segments, as shown in Fig. 10a. The densely stacked state helps reduce the resistance of the cylindrical battery 190 to a level suitable for rapid charging (e.g., 4 milliohms) or below. The resistance may be at least 0.5 mΩ, or at least 1.0 mΩ, and / or 3.8 mΩ or less, 3.5 mΩ or less, or 3 mΩ or less.

[0622] The structures of the uncoated portions 146a, 146b can be changed to the structures according to the above examples (modifications). Furthermore, a conventional uncoated portion structure can be applied to any of the uncoated portions 146a, 146b without limitation.

[0623] Fig. 24 is a sectional view showing a cylindrical battery 210 according to still another example along the Y-axis.

[0624] With reference to Fig. 24 includes the cylindrical battery 210 which is Fig. 13, and the configuration other than the electrode assembly 100 is substantially the same as that shown in Fig. 17 illustrated cylindrical battery 140. Therefore, the arrangement described with reference to Fig. 13 and Fig. The configuration described in section 17 can be applied essentially identically in this example.

[0625] For example, the first and second uncoated portions 146a, 146b of the electrode assembly 100 are divided into a plurality of segments, and the plurality of segments are bent in a radial direction of the electrode assembly 100, for example, from the outer periphery to the core. At this time, the first portion B1 and the second portion B3 of the first uncoated portion 146a have a lower height than the other portions and do not have a segment, and thus are not significantly bent. This is the same for the second uncoated portion 146b.

[0626] In this example, the bending surface region F may also include a segment skip region a1, a segment height-variable region a2, and a segment height-uniform region a3 from the core to the outer circumference. However, since the second section B3 is not bent, the radial length of the bending surface region F may be shorter than that of the former example.

[0627] As in the Fig. 10c, Fig. 10d and Fig. As shown in Fig. 10e, the bending surface region F includes a region b1 with a uniform number of overlapping layers besides the segment skipping region a1 in which the number of overlapping layers of segments is 10 or more.

[0628] The bending surface area F may also include a region b2 with a decreasing number of overlap layers adjacent to the second section B3 of the electrode assembly 110, in which the number of overlapping layers gradually decreases from segment to segment toward the outer periphery. For example, the region b1 with a uniform number of overlap layers may be set as the welding target area.

[0629] In the bending surface area F, the preferred numerical ranges of the ratio (a2 / c), which is a ratio of the height-variable area a2 to a radius area (c) containing segments, the ratio (b1 / c) of the area b1 with a uniform number of overlap layers to the radius area (c) containing segments, and the ratio of the area of ​​the area b1 with a uniform number of overlap layers to the area of ​​the bending surface area F have already been described above and will therefore not be described again.

[0630] The first current collector 144 may be welded to the bending surface area F of the first uncoated portion 146a and the second current collector 145 may be welded to the bending surface area F of the second uncoated portion 146b.

[0631] The overlapping relationship of the region b1 with a uniform number of overlap layers and the region b2 with a decreasing number of overlap layers with the welding region W, the outer diameter of the first current collector 144 and the second current collector 145, the configuration in which the first portion B1 does not close the core by at least 10% or more of its diameter, and the like are substantially the same as described above.

[0632] Meanwhile, the second portion B3 has no segment and has a height lower than that of the third portion B2. Accordingly, when the first uncoated portion 146a is bent, the second portion B3 is substantially not bent. In addition, since the second portion B3 is sufficiently spaced from the bead portion 147, it is possible to solve the problem of the second portion B3 being damaged during the press-fitting of the bead portion 147.

[0633] The structures of the uncoated portions 146a, 146b can be changed to the structures according to the above examples (modifications). Furthermore, a conventional uncoated portion structure can be applied to any of the uncoated portions 146a, 146b without limitation.

[0634] Fig. 25 is a sectional view showing a cylindrical battery 220 according to still another example along the Y-axis.

[0635] With reference to Fig. 25 contains the cylindrical battery 220 which is Fig. 24, and the configuration other than the electrode assembly 100 is substantially the same as that shown in Fig. 21 illustrated cylindrical battery 180. Therefore, the battery 180 illustrated with reference to Fig. 21 and Fig. 24 described configuration can be applied essentially identically in this example.

[0636] For example, the first and second uncoated portions 146a, 146b of the electrode assembly 100 are divided into a plurality of segments, and the plurality of segments are bent from the outer periphery toward the core. At this time, the first portion B1 and the second portion B3 of the first uncoated portion 146a have a lower height than the other portions and do not have a segment, and thus are not significantly bent. This is the same for the second uncoated portion 146b.

[0637] Therefore, the bending surface area F in this example can be similar to the example of Fig. 24 include a segment skip region a1, a segment height-variable region a2, and a segment height-uniform region a3 from the core to the outer circumference. However, since the second section B3 is not bent, the radial length of the bending surface region F can be shorter than that of the former example.

[0638] As in the Fig. 10c, Fig. 10d and Fig. As shown in Fig. 10e, the bending surface region F includes a region b1 with a uniform number of overlapping layers besides the segment skipping region a1 in which the number of overlapping layers of segments is 10 or more.

[0639] The bending surface area F may also include a region b2 with a decreasing number of overlap layers adjacent to the second section B3 of the electrode assembly 110, in which the number of overlapping layers gradually decreases from segment to segment toward the outer periphery. For example, the region b1 with a uniform number of overlap layers may be set as the welding target area.

[0640] In the bending surface area F, the preferred numerical ranges of the ratio (a2 / c), which is a ratio of the height-variable area a2 to a radius area including segments (c), the ratio (b1 / c) of the area b1 with a uniform number of overlap layers to the radius area (c) including segments, and the ratio of the area of ​​the area b1 with a uniform number of overlap layers to the area of ​​the bending surface area F have already been described above and will therefore not be described again.

[0641] The first current collector 144 may be welded to the bending surface area F of the first uncoated portion 146a and the second current collector 176 may be welded to the bending surface area F of the second uncoated portion 146b.

[0642] The overlapping relationship of the region b1 with a uniform number of overlap layers and the region b2 with a decreasing number of overlap layers with the welding region W, the outer diameter of the first current collector 144 and the second current collector 176, the configuration in which the first portion B1 does not close the core by at least 10% or more of its diameter, and the like are substantially the same as described above.

[0643] The structures of the uncoated portions 146a, 146b can be changed to the structures according to the previous examples (modifications). Furthermore, the conventional uncoated portion structure can be applied to any of the uncoated portions 146a, 146b without limitation.

[0644] In the previous examples (modified examples), the first current collector 144 and the second current collector 176 included in the cylindrical battery 170, 180, 200, 220 including the terminal 172 may have an improved structure as shown in Fig. 26 and Fig. 27 shown.

[0645] The improved structure of the first current collector 144 and the second current collector 176 can contribute to reducing the resistance of the cylindrical battery, improving vibration resistance, and improving energy density. In particular, the first current collector 144 and the second current collector 176 are more effective when used in a large cylindrical battery with a diameter-to-height ratio greater than 0.4.

[0646] Fig. 26 is a plan view showing the structure of the first current collector 144 according to an example.

[0647] Referring to Fig. 23 and Fig. 26, the first current collector 144 may include an edge portion 144a, a first coupling portion 144b of the uncoated portion, and a terminal coupling portion 144c. The edge portion 144a is disposed on the electrode assembly 110. The edge portion 144a may have a substantially rim shape with a void (S open). In the drawings of the present disclosure, only a case where the edge portion 144a has a substantially circular edge shape is illustrated, but the present disclosure is not limited thereto. The edge portion 61 may have a substantially rectangular edge shape, a hexagonal edge shape, an octagonal edge shape, or other edge shapes other than the one illustrated. The number of the edge portion 144a may be increased to two or more. In this case, another edge portion in a edge shape may be provided on the inner side of the edge portion 144a.

[0648] The terminal coupling portion 144c may have a diameter greater than or equal to the diameter of the flat portion 172c formed on the bottom surface of the terminal 172 to secure a welding area for coupling with the flat portion 172c formed on the bottom surface of the terminal 172.

[0649] The coupling portion 144b of the first uncoated portion extends inwardly from the edge portion 144a and is coupled to the uncoated portion 146a by welding. The terminal coupling portion 144c is spaced from the coupling portion 144b of the first uncoated portion and is positioned within the edge portion 144a. The terminal coupling portion 144c may be coupled to the terminal 172 by welding. The terminal coupling portion 144c may, for example, be located approximately in the center of the interior space (S open) surrounded by the edge portion 144a. The terminal coupling portion 144c may be provided at a position corresponding to the hole formed in the core C of the electrode assembly 110. The terminal coupling portion 144c may be configured to cover the hole formed in the core C of the electrode assembly 110 so that the hole formed in the core C of the electrode assembly 110 is not exposed from the terminal coupling portion 144c. For this purpose, the terminal coupling portion 144c may have a larger diameter or a larger width than the hole formed in the core C of the electrode assembly 110.

[0650] The coupling portion 144b of the first uncoated portion and the terminal coupling portion 144c may not be directly connected, but may be arranged to be spaced apart from each other and indirectly connected by the edge portion 144a. Since the first current collector 144 has a structure in which the coupling portion 144b of the first uncoated portion and the terminal coupling portion 144c are not directly connected to each other, but are connected by the edge portion 144c as above, when an impact and / or vibration occurs on the cylindrical battery 200, it is possible to disperse the impact applied to the coupling portion between the coupling portion 144b of the first uncoated portion and the first uncoated portion 146a and the coupling portion between the terminal coupling portion 144c and the terminal 172.In the drawings of the present disclosure, only a case where four coupling portions 144b of the first uncoated portion are provided is illustrated, but the present disclosure is not limited thereto. The number of coupling portions 144b of the first uncoated portion may be selected in consideration of the manufacturing difficulty according to the complexity of the shape, electrical resistance, and space (p. open ) within the edge portion 144a may be determined differently taking into account the electrolyte impregnation and the like.

[0651] The first current collector 144 may further include a bridge portion 144d extending inward from the edge portion 144a and connected to the terminal coupling portion 144c. At least a portion of the bridge portion 144d may have a smaller cross-sectional area compared to the coupling portion 144b of the first uncoated portion and the edge portion 144a. For example, at least a portion of the bridge portion 144d may be formed to have a smaller width and / or thickness compared to the coupling portion 144b of the first uncoated portion. In this case, the electrical resistance in the bridge portion 144d increases. As a result, when a current flows through the bridge portion 144d, the relatively large resistance causes a portion of the bridge portion 144d to melt due to overcurrent heat...

Claims

[1] Electrode assembly (A; 80) comprising a positive electrode (10), a negative electrode (11) and a separator (12) arranged therebetween, wherein the positive electrode (10), the negative electrode (11) and the separator (12) are wound around a winding axis (Y), wherein the negative electrode (11) has a negative active material portion coated with a negative active material and an uncoated portion (43) which is free of the negative active material, wherein the uncoated portion is located at an edge of the negative electrode (11) extending along a winding direction (X), wherein the uncoated portion (43) is designed to provide an electrical connection to the negative electrode (11), wherein the uncoated portion comprises a plurality of separate tabs (61) which are individually bendable in a radial direction, wherein a height of an outermost region having an outermost winding turn of the uncoated portion is smaller than heights of the plurality of separate tabs (61), wherein the plurality of separate tabs (61) are bent in the direction of the winding axis (Y) to form a bending surface area (F), wherein the bending surface region (F) comprises a region with a uniform number of overlap layers (b1), in which the number of overlapping layers of the separate tabs (61) is uniform, and a region with a decreasing number of overlap layers (b2) located adjacent to the region with a uniform number of overlap layers (b1), in which the number of overlapping layers of the separate tabs (61) decreases in a direction away from the region with a uniform number of overlap layers (b1), and wherein a combined thickness of the overlapping layers of the separate tabs (61) in the region with a uniform number of overlapping layers (b1) is between 50 µm and 700 µm. [2] The electrode assembly (A; 80) according to claim 1, wherein a height of an innermost region having an innermost winding turn of the uncoated portion is smaller than heights of the plurality of separate tabs (61). [3] The electrode assembly (A; 80) of claim 1, wherein the first uncoated portion (43; 146a) comprises a first portion (B1) having an innermost winding turn, a second portion (B3) corresponding to the outermost portion, and a third portion (B2) disposed between the first portion (B1) and the second portion (B3). [4] The electrode assembly (A; 80) according to claim 3, wherein a height of the first portion (B1) is smaller than the height of the third portion (B2). [5] Electrode assembly (A; 80) according to claim 3 or 4, wherein the second portion (B3) is defined as the electrode tab in a state bent along a radial direction of the electrode assembly (A; 80); and / or wherein the third portion (B2) is defined as the electrode tab in a state bent along a radial direction of the electrode assembly (A; 80). [6] Electrode assembly (A; 80) according to one of claims 3 to 5, wherein the third section (B2) is at least partially formed with a plurality of separate tabs (61) which are individually bendable. [7] Electrode assembly (A; 80) according to claim 6, wherein a width in the winding direction (X) is determined, wherein the width of one or more or each of the plurality of separate tabs (61): decreases in the winding axis direction away from the active material layer (42); or decreases in the winding axis direction away from the active material layer (42) and then increases; or increases and then decreases in the winding axis direction away from the active material layer (42); or increases along the winding axis direction away from the active material layer (42) and then remains constant; or decreases along the winding axis direction away from the active material layer (42) and then remains constant; or remains unchanged along the winding axis direction. [8] Electrode assembly (A; 80) according to claim 6 or 7, wherein the width of at least one of the plurality of separate tabs (61) is smaller at an outermost position than at an innermost position in the winding axis direction; or the width of at least one of the plurality of separate tabs (61) at an outermost position is equal to that at an innermost position in the winding axis direction. [9] Electrode assembly (A; 80) according to one of claims 6 to 8, wherein the plurality of separate tabs (61) are shaped to form interior angles proximal to the active material layer (42) which increase individually or in groups in the winding direction (X); and / or wherein the interior angles of the plurality of separate tabs (61) increase individually or in groups in the range of 60 to 85 degrees in a direction parallel to the winding direction (X), wherein the interior angle (θ) is an angle between a straight line extending from a bottom portion (63a) of a cut groove (63) and a straight line extending from a side portion (63b) of the tab (61). [10] Electrode assembly (A; 80) according to claim 6 or claim 8, wherein the width of one or more or each of the plurality of separate tabs (61) decreases in the winding axis direction away from the active material layer (42), wherein an interior angle θ of a separate tab (61) located at a position corresponding to a radial distance r from the winding axis (Y) of the electrode assembly (A; 80) satisfies the following: cos-1(0.5∗Dr)≤θ≤tan−1(2∗H∗tanθrefer2∗H−p∗tanθrefer) where D is a width of the separate tab (61) in the winding direction (X), r is a radial distance from the winding axis (Y) of a respective separate tab (61), H is a height of the separate tab (61), and p is a separation distance of the separate tab (61). [11] Electrode assembly (A; 80) according to one of claims 6 to 10, wherein one or more or each of the plurality of separate tabs (61) has a side (63b) that is outwardly convex or inwardly convex; and / or wherein one or more or each of the plurality of separate tabs (61) has a rounded corner on a respective outer side. [12] Electrode assembly (A; 80) according to one of claims 6 to 11, wherein the cut groove (63) is formed between each of the separate tabs (61) adjacent in the winding direction (X), whereby corners of the cutting groove (63) are rounded. [13] The electrode assembly (A; 80) according to claim 12, wherein the corners of the cut groove (63) are rounded with a radius of curvature of 0 to 0.1 mm or 0.01 mm to 0.05 mm. [14] Electrode assembly (A; 80) according to claim 12 or 13, wherein an inner side of the cut groove (63) between the corners is flat; and / or wherein an inner side of the cut groove (63) is spaced from the active material layer (42) by a fixed distance, in particular by 0.2 mm to 4 mm. [15] Electrode assembly (A; 80) according to one of claims 12 to 14, wherein the plurality of separate tabs (61) are spaced apart from each other in the winding direction (X) by a separation distance (P), where the separation distance (P) is 0.05 mm to 1.00 mm. [16] Electrode assembly (A; 80) according to one of claims 12 to 15, wherein the plurality of separate tabs (61) are made of an aluminum foil. [17] The electrode assembly (A; 80) according to any one of claims 12 to 16, wherein one or more or each of the plurality of separate tabs (61) are bent at a position located on an inner side of the adjacent cut groove (63) or offset outwardly from an inner side of the adjacent cut groove (63) by 1 mm or less. [18] Electrode assembly (A; 80) according to one of claims 6 to 17, wherein one or more or each of the plurality of separate tabs (61) have lateral sides which define boundaries of the respective separate tab (61) in the winding direction (X), where: the lateral sides are provided such that, after bending the respective separate tab (61), they form a central angle of 45 degrees or less at the winding axis (Y) of the electrode assembly (A; 80); and / or the lateral sides are provided such that, after bending of the respective separate tab (61), they form central angles at the winding axis (Y) of the electrode assembly (A; 80) which remain constant. [19] Electrode assembly (A; 80) according to one of claims 6 to 18, wherein for one or more or each of the plurality of separate tabs (61) D(r) satisfies the following formula: 1≤D(r)≤(2⋅π⋅r / 360∘)⋅45∘ where r is a distance of the respective separate tab (61) from the winding axis (Y) of the electrode assembly (A; 80) in the radial direction and D(r) is a width of the respective separate tab (61) in the winding direction (X). [20] Electrode assembly (A; 80) according to claim 19, where D(r) increases continuously or stepwise as r increases; or where D(r) decreases continuously or stepwise as r increases; or where D(r) increases continuously or stepwise and then decreases as r increases. [21] Electrode assembly (A; 80) according to one of claims 6 to 20, wherein the widths of the plurality of separate tabs (61) increase in the winding direction (X) at a constant rate in the winding direction (X) of the electrode assembly (A; 80); and / or wherein the widths of the plurality of separate tabs (61) increase in the radial direction depending on a distance r from the winding axis (Y) of the electrode assembly (A; 80); and / or wherein the widths of the plurality of separate tabs (61) vary within a range of 1 mm to 11 mm. [22] Electrode assembly (A; 80) according to one of the preceding claims, wherein in at least a partial area of ​​the second section (B3) and / or the third section (B2) of the first uncoated section (43; 146a), the height of the first uncoated section (43; 146a), in particular of the plurality of separate tabs (61) thereof, changes continuously or stepwise in the winding direction (X). [23] Electrode assembly (A; 80) according to one of the preceding claims, wherein the third section (B2) is divided into several areas along the winding direction (X), wherein the height of the first uncoated portion (43; 146a) differs in two different regions, and in particular the heights of the plurality of separate tabs (61) differ in two different regions. [24] Electrode assembly (A; 80) according to one of claims 6 to 23, wherein the first uncoated portion (43; 146a) comprises: a height-variable region (②) in which the heights of the separate tabs (61) are gradually varied from a first height (h1) to an (N-1)th height h N-1 increase, where N is a height index and a natural number of 2 or more, in particular 2 to 30; and a uniform height area (3) in which the heights of the separate tabs (61) remain unchanged at an Nth height h N be kept, where h N greater than h N-1 is. [25] Electrode assembly (A; 80) according to claim 24, wherein separate tabs (61) with an equal height hk are arranged in an equal winding turn around the winding axis (Y); and / or wherein at least 90% of a hollow core portion of the electrode assembly (A; 80), with respect to a size in the radial direction, remains uncovered after bending by the separate tabs (61); and / or where rk indicates a distance from the winding axis (Y) in a radial direction and r c a radius of a central hollow portion of the electrode assembly (A; 80) and hk indicates the height of separate tabs (61) located at rk, hk and rk are such that they satisfy the following: 2 mm≤hk≤rk-α⋅rc where α is 0.90 to 1. [26] Electrode assembly (A; 80) according to one of claims 6 to 25, wherein the electrode assembly (A; 80) comprises: a tab skip area (1), for example the first section (B1), which does not have separate tabs (61); a height-variable region (2) in which the separate tabs (61) have variable heights; and a uniform height region (3) in which the separate tabs (61) have a uniform height in a radial direction or in the winding direction (X), wherein the plurality of separate tabs (61) arranged in the height-variable region (②) and the height-uniform region (®) are bent in the radial direction to form a bending surface region (F). [27] Electrode assembly (A; 80) according to claim 26, wherein the third section (B2) corresponds to the height-variable area (②) and the height-uniform area (③); or where the height-variable area (②) and the height-uniform area (③) correspond to the second section (B3) and the third section (B2) respectively. [28] Electrode assembly (A; 80) according to claim 26 or 27, where in the height-variable area (②) and the height-uniform area (③) a maximum height h max the separate tabs (61) fulfill the following formula: hmax≤Wfoil−Wscrap,min−Wmargin,min−Wgap where W foil is a width of a current collector foil before separate tabs (61) are formed; Wscrap,min a width corresponding to a minimum cutting waste margin when separate tabs (61) are formed by cutting the current collector foil; W margin,min is a width corresponding to a minimum meander edge of the separator (12); and W gap a width corresponding to an insulating gap between one end of the separator (12) and one end of the second electrode (10; 11) facing the first electrode (10; 11) with the separator (12) being interposed therebetween. [29] Electrode assembly (A; 80) according to claim 28, wherein the first electrode (10; 11) is a positive electrode (10) and the insulating gap (W gap ) is in the range of 0.2 mm to 6 mm; and / or wherein the first electrode (10; 11) is a negative electrode (11) and the insulating gap (W gap ) is in the range of 0.1 mm to 2 mm. [30] Electrode assembly (A; 80) according to claim 28 or 29, wherein: the minimum cutting waste margin (W scrap,min ) is zero or in the range of 1.5 mm to 8 mm; and / or the minimal meander edge (W margin,min ) is in the range of 0 to 1 mm; and / or [31] Electrode assembly (A; 80) according to one of claims 26 to 30, wherein: the heights of the separate tabs (61) arranged in the height-variable region (2) increase gradually or stepwise within the range of 2 mm to 10 mm; and / or a ratio of a radial size of the tab skip area (1) to a radius of the electrode assembly (A; 80) excluding a hollow core portion in the radial direction of the electrode assembly (A; 80) is 10% to 40%; and / or a ratio of a radial size of the height-variable region (2) to a radial size corresponding to the height-variable region (2) and the height-uniform region (3) in the radial direction of the electrode assembly (A; 80) is 1% to 50%; and / or a ratio of a length of an electrode region corresponding to the tab skip region (1) to a total length of a first electrode (10; 11) in the winding direction (X) is 1% to 30%, wherein the first electrode is either the positive electrode (10) or the negative electrode (11); and / or a ratio of a length of an electrode region corresponding to the height-variable region (2) to a total length of the first electrode (10; 11) in the winding direction (X) is 1% to 40%; and / or wherein a ratio of a length of an electrode region corresponding to the uniform height region (3) to a total length of the first electrode (10; 11) in the winding direction (X) is 50% to 90%. [32] Electrode assembly (A; 80) according to one of claims 6 to 31, wherein widths in the winding direction (X) and / or heights in the winding axis direction of the plurality of separate tabs (61): increase continuously or stepwise in the winding direction (X); and / or increase and then decrease in the winding direction (X); and / or decrease in the winding direction (X) and then increase. [33] Electrode assembly (A; 80) according to one of claims 6 to 32, wherein the plurality of separate tabs (61) form a plurality of tab groups along a direction parallel to the winding direction (X) of the electrode assembly (A; 80), wherein: separate tabs (61) belonging to one of the tab groups have an equal width in the winding direction (X) and / or an equal height in the winding axis direction; and / or separate tabs (61) belonging to another of the tab groups have increasing widths in the winding direction (X) and / or increasing heights in the winding direction (X); and / or three consecutive groups of tabs each have widths W1, W2 and W3 in the winding direction (X), wherein a ratio W3 / W2 is smaller than a ratio W2 / W1. [34] Electrode assembly (A; 80) according to one of the preceding claims, wherein the first portion (B1) and / or the second portion (B3) is / are not formed into separate tabs (61) and is / are not bent along a radial direction of the electrode assembly (A; 80). [35] The electrode assembly (A; 80) according to any one of the preceding claims, wherein an insulating coating layer, for example a polymer resin and an inorganic filler dispersed in the polymer resin, is formed at a boundary between the active material layer (42) and the provided first uncoated portion (43; 146a). [36] Electrode assembly (A; 80) according to claim 35, wherein: the insulation coating layer is formed to cover a boundary portion of the active material layer (42) and the first uncoated portion (43; 146a) along the winding direction (X); and / or the insulation coating layer is formed to cover the boundary portion of the active material layer (42) and the first uncoated portion (43; 146a) along the winding axis direction with a width of 0.3 mm to 5 mm; and / or one end of the insulation coating layer is arranged within the range of -2 mm to 2 mm along the winding axis direction with respect to one end of the separator (12); and / or the insulation coating layer is exposed from the separator (12); and / or an inner side of a cut groove (63) formed in the first uncoated portion (43; 146a) is formed, and the insulation coating layers are spaced apart by a distance of 0.5 mm to 2 mm; and / or one end of the insulation coating layer in the winding axis direction is arranged within the range of -2 mm to +2 mm with respect to a lower end of the cut groove (63) formed in the first uncoated portion (43; 146a). [37] The electrode assembly (A; 80) according to claim 36, wherein the second electrode (10; 11) is coated with an active material layer (42) in a second active material portion, and an end of the second active material portion in the winding axis direction overlaps the insulation coating layer in a viewing direction in a radial direction. [38] Electrode assembly (A; 80) according to one of the preceding claims, wherein the third section (B2) and / or the second section (B3) are each formed with a plurality of separate tabs (61) which are individually bendable, wherein the electrode assembly (A; 80) comprises a bending surface region (F) formed by bending the plurality of separate tabs (61) along a radial direction of the electrode assembly (A; 80). [39] The electrode assembly (A; 80) according to claim 38, wherein, when the number of the separate tabs (61) meeting a virtual line parallel to the winding axis direction at any radial location of the bending surface region (F) based on a core center of the electrode assembly (A; 80) is defined as the number of overlapping layers of the separate tabs (61) at the corresponding radial location, wherein the bending surface area (F) comprises: a region with a uniform number of overlap layers (b1), in which the number of overlapping layers of the separate tabs (61) is uniform, in particular 10 or more, or 10 to 35, along a radial direction, and a region with decreasing number of overlap layers (b2) in which the number of overlapping layers of the separate tabs (61) continuously decreases in the radial direction. [40] The electrode assembly (A; 80) according to claim 39, wherein a radial size of the region with a uniform number of overlap layers (b1) and the region with a decreasing number of overlap layers (b2) corresponds to a radial size of a region in which the plurality of separate tabs (61) are formed. [41] Electrode assembly (A; 80) according to claim 39 or 40, wherein the electrode assembly (A; 80) comprises a tab skip region (1) having no separate tabs (61), a height-variable region (2) in which separate tabs (61) have variable heights, and a height-uniform region (3) in which separate tabs (61) have a uniform height in the order along the radial direction; and / or wherein a radial position from the winding axis (Y) of the electrode assembly (A; 80) at which the region with a uniform number of overlap layers (b1) begins corresponds to a radial position at which the height-variable region (②) begins. [42] The electrode assembly (A; 80) according to claim 39, wherein a ratio of a radial size of the uniform overlap layer number region (b1) to a radial size of the uniform overlap layer number region (b1) and the decreasing overlap layer number region (b2) is 30% to 85%. [43] Electrode assembly (A; 80) according to any one of claims 38 to 42, further comprising: a current collector (41) welded to the bending surface area (F), wherein a welding region (W) of the current collector (41) overlaps the region with a uniform number of overlap layers (b1) by at least 50% in the radial direction of the electrode assembly (A; 80). [44] Electrode assembly (A; 80) according to claim 43, wherein the welding region (W) of the current collector (41) extends so as to also overlap the region with decreasing overlap layer number (b2). [45] An electrode assembly (A; 80) according to claim 43 or 44, wherein an edge of the current collector (41) is disposed on the bending surface region (F) to cover one end of a bent portion of outermost separate tabs (61) in the radial direction of the electrode assembly (A; 80). [46] Electrode assembly (A; 80) according to claim 44 or 45, wherein the current collector (41) is welded to the bending surface region (F), in particular such that it has a welding strength of 196 kPa (2 kgf / cm 2 ) or more or 392 kPa (4 kgf / cm 2 ) or more. [47] Electrode assembly (A; 80) according to one of the preceding claims, wherein the first uncoated portion (43; 146a) is made of a metal foil, in particular an aluminum foil, wherein the metal foil has an elongation of 1.5% to 3.0% and a tensile strength of 245 MPa (25 kgf / mm 2 ) up to 343 MPa (35 kgf / mm 2 ). [48] ​​The electrode assembly (A; 80) of claim 47, wherein the first electrode (10; 11) has a bulge length of less than 20 mm, the first electrode being either the positive electrode (10) or the negative electrode (11). [49] Electrode assembly (A; 80) according to one of the preceding claims, wherein the first active material section has a short side along the winding axis direction and a long side along the winding direction (X), where the size ratio of the short side to the long side is 1% to 4%. [50] Electrode assembly (A; 80) according to one of the preceding claims, wherein a height of the second portion (B3) decreases continuously or stepwise in the radial direction or winding direction (X). [51] Electrode assembly (A; 80) according to one of the preceding claims, wherein the second section (B3) and the third section (B2) are formed with a plurality of separate tabs (61) which are individually bendable, wherein widths and / or heights of the separate tabs (61) in the second section (B3) are greater than those of the separate tabs (61) in the third section (B2). [52] Electrode assembly (A; 80) according to one of claims 6 to 51, wherein the third section (B2) comprises a tab skip region (1) which has no separate tabs (61). [53] Electrode assembly (A; 80) according to claim 52, wherein: the third section (B2) comprises a plurality of tab skip regions (1) which optionally have widths that increase or decrease along the winding direction (X); and / or a height of the tab skip area (1) is equal to a height of the first section (B1) or the second section (B3); and / or the plurality of separate tabs (61) are arranged within a preset central angle, which is, for example, 20 degrees or more, on the winding axis (Y) of the electrode assembly (A; 80); and / or the plurality of separate tabs (61) are arranged in at least two circular sectoral regions or polygonal regions which are arranged in a plan view in the winding axis direction of the electrode assembly (A; 80). [54] Electrode assembly (A; 80) according to one of the preceding claims, wherein the second electrode (10; 11) has a second active material portion coated with another active material layer (42) and a second uncoated portion (145) which is free from the other active material layer (42) at an edge of the second electrode (10; 11) extending along the winding direction (X), wherein the second uncoated portion (145) is designed to provide an electrical connection to a first electrode (10; 11), the first electrode being either the positive electrode (10) or the negative electrode (11), wherein the second uncoated portion (145) is partially divided into a plurality of separate tabs (61) which are individually bendable. [55] Battery comprising: the electrode assembly (A; 80) according to any one of claims 1 to 54; a battery case (142) having an open first end surface and a second end surface opposite the first end surface, wherein the electrode assembly (A; 80) is housed in the battery case (142) and the battery case (142) is electrically connected to the positive electrode (10) or the negative electrode (10); a sealing body (143) adapted to seal the open first end surface of the battery case (142); and a terminal (172) electrically connected to the other of the positive electrode (10) and the negative electrode (11) and having a surface exposed to the outside of the battery case (142). [56] The battery according to claim 55, wherein the battery further comprises a current collector (41) welded to the uniform overlap layer number region (b1) such that at least a part of a welding region (W) of the current collector (41) overlaps the uniform overlap layer number region (b1). [57] Battery, wherein the battery case (142) has a bead portion (147) which is pressed inward at a region adjacent to the first end surface, the surface of the bead portion (147) and the second portion (B3) being spaced apart from each other by a predetermined distance. [58] The battery according to claim 57, wherein an indentation depth (D1) of the bead portion (147) is equal to or greater than a distance (D2) from the inner periphery of the battery case (142) to a boundary between the second portion (B3) and the third portion (B2). [59] A battery according to claim 57 or 58, further comprising: a current collector (41) electrically coupled to the third section (B2); and an insulator (146) configured to cover the current collector (41) and having an edge disposed and fixed between the inner periphery of the bead portion (147) and the current collector (41). [60] Battery according to claim 59, wherein a diameter of the current collector (41) is smaller than a minimum inner diameter of the inner circumference of the bead portion (147) and a diameter of the current collector (41) is equal to or larger than an outermost diameter of the third portion (B2); and / or wherein the current collector (41) is arranged higher than the bead portion (147) in the winding axis direction. [61] Battery according to one of claims 57 to 60, wherein the sealing body (143) comprises a cap (143a) forming, for example, the terminal (172), which is designed to seal the open first end side of the battery case (142), a seal (143b; 178b) arranged between an edge of the cap (143a) and the open end of the battery case (142), and a crimping portion (148) which is bent and extends into the battery case (142) and is designed to surround and hold the edge of the cap (143a) together with the seal (143b; 178b). [62] A battery according to any one of claims 57 to 61, further comprising: a first current collector (144) electrically connected to the first uncoated portion (43; 146a), wherein the terminal (172) is a through-connector inserted into a perforation hole formed in the second end face of the battery case (142), wherein the lead-through terminal is insulated from the battery case (142) and electrically connected to the first current collector (144), for example by an insulator (146) disposed between an inner surface of a lower portion of the battery case (142) and an upper surface of the first current collector (144) to electrically insulate the inner surface of the lower portion of the battery case (142) and the first current collector (144). [63] Battery according to claim 62, wherein the insulator (146) has a thickness corresponding to a distance between the inner surface of the lower portion of the battery case (142) and the upper surface of the first current collector (144) and is in close contact with the inner surface of the lower portion of the battery case (142) and the upper surface of the first current collector (144); and / or wherein the terminal (172) includes a flat portion (172c) at a lower end thereof, the insulator (146) has an opening for exposing the flat portion (172c), and the flat portion (172c) is welded to the first current collector (144) through the opening. [64] The battery of any one of claims 57 to 63, wherein the second electrode (10; 11) comprises a second active material portion coated with an active material layer (42) and a second uncoated portion (145) not coated with an active material layer (42) along the winding direction (X), the second electrode (10; 11) has a first polarity, at least a portion of the second uncoated portion (145) is defined as an electrode tab, and the battery further includes a second current collector (145; 176) electrically connected to the second uncoated portion (145) and having an edge at least partially coupled to a sidewall of the battery case (142). [65] Battery according to one of claims 62 to 64, wherein the second electrode (10; 11) has a second active material portion coated with a second active material and a second uncoated portion (145) which is free of the second active material, wherein the second uncoated portion (145) is located at an edge of the second electrode (10; 11) extending along the winding direction (X), wherein the second uncoated portion (145) provides an electrical connection to the second electrode (10; 11), wherein the battery further includes a second current collector (145; 176) electrically connected to the second uncoated portion (145) and having an edge electrically coupled to a side wall of the battery case (142) extending between the first end face and the second end face, wherein the first current collector (144) has an outer diameter equal to or greater than that of the second current collector (145; 176). [66] Battery according to claim 65, wherein the first current collector (144) and the second current collector (145; 176) are each welded to the first uncoated portion (43; 146a) and the second uncoated portion (145) along a radial direction of the electrode assembly (A; 80) to form a respective weld pattern, wherein a length of the welding pattern of the first current collector (144) is longer than a length of the welding pattern of the second current collector (145; 176). [67] A battery according to claim 66, wherein the welding pattern of the first current collector (144) and the welding pattern of the second current collector (145; 176) are arranged at substantially the same distance from the winding axis (Y) of the electrode assembly (A; 80). [68] Battery according to one of claims 65 to 67, wherein the battery case (142) has a bead portion (147) pressed inwardly adjacent to the first end surface, wherein the edge of the second current collector (145; 176) is electrically connected, in particular welded, to the bead portion (147). [69] The battery according to claim 68, wherein a portion of the second current collector (145; 176) in electrical contact with the second uncoated portion (145) is surrounded by the bead portion (147) in a plan view in the winding axis direction. [70] A battery according to claim 68 or 69, wherein the battery comprises a cap (143a) having an edge supported by the bead portion (147) and having no polarity, a gasket (143b; 178b) disposed between the edge of the cap (143a) and the open end of the battery case (142), and a crimping portion (148) which is bent and extends into the open end of the battery case (142) and is adapted to surround and hold the edge of the cap (143a) together with the gasket (143b; 178b), and the edge of the second current collector (145; 176) is disposed and fixed between the bead portion (147) and the gasket (143b; 178b) by the crimping portion (148). [71] A battery according to any one of claims 57 to 70, wherein the battery further comprises a current collector (41) having a welding region (W) welded to a region with a uniform overlap layer number (b1) of the first uncoated region, and the overlap layers of the separate tabs (61) of the negative electrode (11) in the welding region (W) have a thickness in the range of 50 µm to 700 µm. [72] Battery pack (300) comprising a plurality of batteries (301) according to any one of claims 55 to 71. [73] The battery pack (300) of claim 72, wherein a diameter to height ratio of the battery is greater than 0.

4. [74] The battery pack (300) of claim 72 or 73, wherein the battery has a form factor of 46110, 4875, 48110, 4880 or 4680. [75] The battery pack (300) according to any one of claims 72 to 74, wherein the plurality of batteries (301) are arranged in a predetermined number of columns such that a terminal (172) of each battery and an outer surface of a bottom portion of a battery case (142) of each battery face upward. [76] Battery pack (300) according to claim 75, further comprising: a plurality of busbars (210) configured to connect the plurality of batteries (301) in series and parallel, wherein the plurality of busbars (21) are arranged at an upper portion of the plurality of batteries (301), and each of the bus bars (210) includes a body portion (211) configured to extend between the terminals (172) of adjacent batteries; a plurality of first bus bar terminals (213) configured to extend from one side of the body portion (211) and electrically coupled to a terminal (172) of a battery located on one side; and a plurality of second bus bar terminals (213) configured to extend from the other side of the body portion (211) and electrically coupled to an outer surface of the bottom of the battery housing (142) of a battery located on the other side. [77] Vehicle (V) comprising the battery pack (300) according to any one of claims 72 to 76.

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