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

Abstract

Disclosed are an electrode assembly, a battery, a battery pack including the same, and an automobile. An electrode assembly, which defines a core portion and an outer circumferential surface by winding a first electrode, a second electrode, and a separator interposed therebetween about an axis, is characterized in that the first electrode includes an uncoated portion exposed to an outside of the separator in a winding axis direction of the electrode assembly at a long side end portion, a portion of the uncoated portion is bent in a radial direction of the electrode assembly to form a bent surface area including a plurality of layers of the uncoated portion, and a number of the layers of the uncoated portion in the winding axis direction of the electrode assembly is 10 or more in a portion of the bent surface area.

Description

Technical Field

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

[0002] In addition to portable devices, secondary batteries, which are highly adaptable to various product groups and have high energy density and other electrical properties, are also widely used in electric vehicles (EVs) or hybrid electric vehicles (HEVs) driven by electric drive sources.

[0003] Such secondary batteries not only have the primary advantage of significantly reducing the use of fossil fuels, but also the advantage of not producing any byproducts when using energy. Therefore, they have attracted much attention as a new energy source that is environmentally friendly and improves energy efficiency.

[0004] Currently, widely used rechargeable batteries include lithium-ion batteries, lithium polymer batteries, nickel-cadmium batteries, nickel-metal hydride batteries, and nickel-zinc batteries. The operating voltage of a single rechargeable battery, or a single cell, is approximately 2.5V to 4.5V. Therefore, if a higher power voltage is required, multiple batteries are sometimes connected in series to form a battery pack. Furthermore, depending on the required charge / discharge capacity of the battery pack, multiple batteries are sometimes connected in parallel to form a battery pack. Therefore, depending on the required power voltage and / or charge / discharge capacity, the number of batteries included in the above-mentioned battery packs and the electrical connection method can be designed in various ways.

[0005] On the other hand, as types of unit secondary battery cells, cylindrical, square, and pouch batteries are disclosed. Cylindrical batteries have a separator membrane, serving as an insulator, sandwiched between the anode and cathode, and this membrane is rolled up to form a gel-roll-shaped electrode assembly, which is then inserted into the battery casing to form the battery. Furthermore, the uncoated portions of both the anode and cathode can be connected to strip electrode tabs, which electrically connect the electrode assembly to the exposed electrode terminals. For reference, the anode electrode terminal is a cover for sealing the opening of the battery casing, and the cathode electrode terminal is the battery casing itself. However, according to existing cylindrical batteries with this structure, the current is concentrated at the strip electrode tabs connected to the uncoated portions of the anode and / or the uncoated portions of the cathode, resulting in high resistance, excessive heat generation, and low current collection efficiency.

[0006] For small cylindrical batteries with form factors of 1865 (diameter: 18mm, height: 65mm) or 2170 (diameter: 21mm, height: 70mm), resistance and heat generation are not major issues. However, when the form factor is increased to make cylindrical batteries suitable for electric vehicles, a lot of heat is generated around the electrode tabs during fast charging, which may lead to the possibility of the cylindrical battery catching fire.

[0007] To address this issue, a cylindrical battery with an improved current-collecting efficiency (a so-called tabless cylindrical battery) has been disclosed. The battery is designed with an uncoated anode and an uncoated cathode located at the upper and lower ends of a gel roll-type electrode assembly, respectively, and the current collector is welded to such uncoated portions.

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

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

[0010] like Figure 2 As shown, electrode assembly A is manufactured by sequentially stacking the anode 10 and cathode 11 together with two separation membranes 12 and then winding them in one direction X. In this case, the uncoated portions of the anode 10 and cathode 11 are arranged in opposite directions. The positions of the anode 10 and cathode 11 can be changed to the opposite positions shown in the illustration.

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

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

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

[0014] When the uncoated portions 10a and 11a are bent, the uncoated portion 32 adjacent to the core of electrode assembly A may block all or most of the cavity 33 located in the core of electrode assembly A. This causes problems in the electrolyte injection process. Specifically, the cavity 33 in the core of electrode assembly A is used as a channel for injecting electrolyte. However, if the corresponding channel is blocked, it is difficult to inject electrolyte. Furthermore, during the insertion of the electrolyte injector into the cavity 33, interference occurs with the uncoated portion 32 bent near the core, potentially causing the uncoated portion 32 to tear.

[0015] Furthermore, the bent portions of the uncoated parts 10a and 11a used for welding current collectors 30 and 31 need to overlap multiple layers without any gaps. Only in this way can sufficient welding strength be obtained, and even when using the latest technologies such as laser welding, the problem of laser penetration into the electrode assembly A and melting and separating the film or active material can be prevented.

[0016] In order for the uncoated portions 10a and 11a to overlap to the same number of layers, based on the position of each winding ring, the uncoated portion 10a and 11a at that position must bend towards the core while covering the uncoated portion of the winding ring inside it. Furthermore, when the interval between the winding rings is set to d, and the bending length of the uncoated portion 10a and 11a of each winding ring is set to e, the bending length e must have a value of d. A length of n (where n is a natural number greater than 2) or more is required. Only in this way can regions with multiple overlapping layers of uncoated portions 10a and 11a be generated in the same quantity. Furthermore, in order to sufficiently obtain regions with an equal number of overlapping layers of uncoated portions 10a and 11a in the radial direction of the electrode assembly, the lengths of the uncoated portions 10a and 11a need to be sufficiently long. However, in the case of electrode assemblies including small cylindrical batteries, the radius is small, and there is no motivation to derive a concept that designs the bending lengths of the uncoated portions 10a and 11a to be sufficiently long. Summary of the Invention

[0017] The problem that the invention aims to solve

[0018] The present invention was made in the context of the prior art as described above, and its object is to provide an electrode assembly having an uncoated portion bending structure in which, when bending the uncoated portions exposed at both ends of the electrode assembly, more than 10 uncoated portions are sufficiently overlapped in the radial direction of the electrode assembly, thereby preventing damage to the separation membrane or active material layer when welding the current collector.

[0019] Another technical problem of the present invention is to provide an electrode assembly that will not be blocked even if the uncoated part is bent.

[0020] Another technical challenge of the present invention is to provide an electrode assembly that increases energy density and reduces resistance.

[0021] Another technical challenge of the present invention is to provide a battery including an electrode assembly with an improved structure, a battery pack including the battery, and a vehicle including the battery pack.

[0022] The technical problem to be solved by the present invention is not limited to the above-mentioned technical problem. Those skilled in the art can clearly understand other technical problems not mentioned through the invention description below.

[0023] Methods for solving problems

[0024] To achieve the aforementioned technical problem, an electrode assembly of one side of the present invention defines the core and outer peripheral surface by winding a first electrode, a second electrode, and a separation membrane between them around an axis. The electrode assembly is characterized in that the first electrode includes an uncoated portion at its long side end that protrudes to the outside of the separation membrane along the winding axis direction of the electrode assembly. A portion of the uncoated portion is bent in the radial direction of the electrode assembly to form a bent surface region including overlapping layers of the uncoated portion. In a portion of the bent surface region, the number of layers of the uncoated portion in the winding axis direction of the electrode assembly is 10 or more.

[0025] In one aspect, defining the total number of winding turns of the first electrode as n1, the value obtained by dividing the winding turn index k at the k-th winding turn position by the total number of winding turns n1 is defined as the relative radius position R relative to the winding turn index k. 1，k At that time, relative to the radius position range of the uncoated part being bent, R satisfies the condition that the number of layers of the uncoated part is 10 or more. 1，k The length ratio of the radius direction interval is at least 30%, where k is a natural number from 1 to n1.

[0026] Preferably, R is a region of relative radius relative to the uncoated portion being bent, where the number of layers in the uncoated portion is 10 or more. 1，kThe ratio of the radius direction interval length is 30% to 85%.

[0027] In another aspect, the second electrode includes an uncoated portion at its long side end that protrudes to the outside of the separation membrane along the winding axis of the electrode assembly. A portion of the uncoated portion is bent in the radial direction of the electrode assembly to form a bent surface region comprising an overlapping layer of the uncoated portion. In a portion of the bent surface region, the number of layers of the uncoated portion in the winding axis direction of the electrode assembly is 10 or more.

[0028] In another aspect, defining the total number of winding turns of the second electrode as n2, the value obtained by dividing the winding turn index k at the k-th winding turn position by the total number of winding turns n2 is defined as the relative radius position R relative to the winding turn index k. 2，k At that time, relative to the relative radius position range where the uncoated portion is bent, R satisfies the condition that the number of layers of the uncoated portion is 10 or more. 2，k The length ratio of the radius direction interval is at least 30%, where k is a natural number from 1 to n².

[0029] Preferably, R is a region of relative radius relative to the uncoated portion that is bent, where the number of layers of the uncoated portion is 10 or more. 2，k The length ratio of the radial direction interval is 30% to 85%.

[0030] In another aspect, in the aforementioned winding structure of the first electrode, from the relative radius position R of the first winding loop... 1，1 To the preset kth The first relative radius position R of the winding loop 1，k The height of the uncoated portion of the section up to this point is less than the number of turns k. +1 relative radius position R 1，k +1 The height of the uncoated portion within the interval of relative radius position 1.

[0031] In another aspect, in the aforementioned winding structure of the first electrode, from the relative radius position R of the first winding loop... 1，1 To the preset kth The first relative radius position R of the winding loop 1，k The height of the uncoated portion of the preceding section is lower than the height of the aforementioned bent surface area formed by the overlap of the uncoated portions of the bend.

[0032] In another aspect, in the aforementioned winding structure of the first electrode, from the relative radius position R of the first winding loop... 1，1up to the kth The first relative radius position R of the winding loop 1，k The section up to this point does not bend towards the core of the electrode assembly.

[0033] In another aspect, in the winding structure of the second electrode, from the relative radius position R of the first winding loop... 2，1 To the preset kth The first relative radius position R of the winding loop 2，k The height of the uncoated portion of the interval up to this point is lower than that of the kth section. +1 winding loop relative radius position R 2，k +1 The height of the uncoated portion within the interval of relative radius position 1.

[0034] On another side, from the relative radius position R of the first winding loop 2，1 To the preset kth The first relative radius position R of the winding loop 2，k The height of the uncoated portion of the preceding section is lower than the height of the uncoated portion of the bent surface area formed by the overlap of the uncoated portions of the bend.

[0035] On another side, from the relative radius position R of the first winding loop 2，1 To the preset kth The first relative radius position R of the winding loop 2，k The uncoated portion of the section up to this point does not bend toward the core of the electrode assembly.

[0036] Preferably, the uncoated portion of the first or second electrode is divided into multiple segments that can be bent independently of each other.

[0037] Preferably, the multiple segments each have a geometric shape with a bend line as the base, and the geometric shape is formed by connecting one or more straight lines, one or more curves, or a combination thereof.

[0038] In one side view, the width of the aforementioned geometric figure decreases in stages or continuously as it moves from the bottom to the top.

[0039] In another aspect, the lower interior angle between the base of the aforementioned geometric figure and the side intersecting the base is between 60 and 85 degrees.

[0040] In another aspect, the lower inner angles of the aforementioned plurality of segments increase in stages or gradually along a direction parallel to the winding direction of the aforementioned electrode assembly.

[0041] On another side, multiple segments each have a trapezoidal shape with a bend line as the base. The radius of the winding loop of the segment, positioned relative to the core center of the aforementioned electrode assembly, is defined as r. The arc length of the winding loop corresponding to the lower part of the segment is defined as L. arc The lower interior angle is set as θ when the application of the slice is assumed to be parallel to the sides of a pair of slices adjacent to a winding loop of radius r. assumption At that time, the actual lower interior angle θ of the pair of adjacent segments is... real Satisfy the following mathematical expression:

[0042] θ real >θ assumption

[0043] θ assumption =90°-360° (L) arc / 2πr) 0.5.

[0044] Taking the core center of the aforementioned electrode assembly as a reference, the arc length L of the winding loop corresponding to the lower part of the aforementioned section is... arc The corresponding circumferential angle is less than 45 degrees.

[0045] In another aspect, taking the core center of the aforementioned electrode assembly as a reference, the overlap rate of adjacent segments arranged in a winding loop of radius r is defined by the mathematical formula (θ). real / θ assumptoin When -1), the overlap rate of the cut is greater than 0 and less than 0.05.

[0046] In another aspect, when drawing a hypothetical circle through a pair of adjacent segments arranged in a winding loop of radius r, with the core center of the aforementioned electrode assembly as a reference, the pair of arcs through each segment overlap each other.

[0047] In another aspect, when the overlap rate of a segment is defined as the ratio of the length of the overlapping arc to the length of the arc passing through each segment, the overlap rate of the segment is greater than 0 and less than 0.05.

[0048] In another aspect, in the aforementioned winding structure of the first electrode, from the relative radius position R of the first winding loop... 1，1 up to the kth The first relative radius position R of the winding loop 1，k The uncoated portion of the section up to this point has a height lower than the relative radius position R. 1，k +1 The height of the uncoated portion within the range of relative radius position 1, without bending towards the core.

[0049] In another aspect, relative to the radius position R 1，1 To R 1，k The length of the aforementioned first electrode relative to the relative radius position R 1，k +1 The ratio of the length of the first electrode to that of 1 is 1% to 30%.

[0050] In another aspect, in the winding structure of the aforementioned first electrode, the kth... +1 winding loop relative radius position R 1，k +1 Uncoated part bending length fd 1，k +1 The relative radius position R of the first winding loop 1，1 Up to the kth Relative radius positions R 1，k Its radial length is short.

[0051] In another aspect, within the winding structure of the first electrode described above, the core radius of the electrode assembly is defined as r. c From the center of the core to 0.90r c The interval was not located at the k-th position. +1 winding loop relative radius position R 1，k +1 The bends in the uncoated section of the interval up to 1 are covered.

[0052] In yet another aspect, the kth +1 winding loop relative radius position R 1，k +1 Uncoated part bending length fd 1，k +1 The radius r of the core c and relative radius position R 1，k +1 The distance d separated from the center of the electrode assembly 1，k +1 Satisfy the following mathematical expression:

[0053] fd 1，k +1 +0.90 r c ≤d1，k +1 .

[0054] In another aspect, in the aforementioned winding structure of the second electrode, the relative radius position R of the first winding loop... 2，1 Up to the kth The first relative radius position R of the winding loop 2，k The uncoated portion of the interval, whose height is lower than the kth... +1 winding loop relative radius position R 2，k +1 The height of the uncoated portion within the range of relative radius position 1, without bending towards the core.

[0055] In another aspect, relative to the radius position R 2，1 To R 2，k The length of the aforementioned second electrode relative to the relative radius position R 2，k +1 The ratio of the length of the second electrode to that of 1 is 1% to 30%.

[0056] In another aspect, in the winding structure of the aforementioned second electrode, located at the kth... +1 winding loop relative radius position R 2，k +1 The bending length fd of the uncoated part 2，k +1 The relative radius position R of the first winding loop 2，1 Up to the kth The first relative radius position R of the winding loop 2，k Its radial length is short.

[0057] In another aspect, in the winding structure of the second electrode described above, the core radius of the electrode assembly is defined as r. c At that time, from the center of the core to 0.90r c The interval is not located at the kth position. +1 winding loop relative radius position R 2，k +1 The bend in the uncoated portion of the second electrode within the range of relative radius 1 is shielded.

[0058] In yet another aspect, the kth +1 winding loop relative radius position R 2，k +1 Uncoated part bending length fd 2，k +1 The radius r of the core c and relative radius position R 2，k +1 The distance d separated from the center of the electrode assembly 2，k +1 Satisfy the following mathematical expression:

[0059] fd 2，k +1 +0.90 r c ≤d 2，k +1 .

[0060] In another aspect, in the winding structure of the aforementioned first electrode, the kth... +1 winding loop relative radius position R 1，k +1 To the preset second relative radius position R of the k@th winding turn 1，k@ The uncoated portion of the interval is cut into multiple segments, and its height gradually or in stages increases along a direction parallel to the winding direction.

[0061] In another side view, the relative radius position R 1，k +1 To R 1，k@ The ratio of the radial length of the interval to the radius of the winding structure of the first electrode excluding the core is 1% to 56%.

[0062] In another aspect, in the aforementioned winding structure of the first electrode, from the preset relative radius position R of the k@+1th winding turn... 1，k@+1 The uncoated portion of the first electrode up to relative radius position 1 is divided into multiple segments, the height of which varies from relative radius position R. 1，k@+1 They are essentially the same up to the relative radius position 1.

[0063] In yet another aspect, in the aforementioned winding structure of the second electrode, the kth... +1 winding loop relative radius position R 2，k +1 To the preset second relative radius position R of the k@th winding turn 2，k@The uncoated portion of the section is divided into multiple segments, and its height increases in stages or gradually along a direction parallel to the winding direction.

[0064] In another side view, the relative radius position R 2，k +1 To R 2，k@ The ratio of the radial length of the interval to the radius of the winding structure of the second electrode excluding the core is 1% to 56%.

[0065] In another aspect, in the winding structure of the aforementioned second electrode, from the second relative radius position R of the k@+1th winding turn... 2，k@+1 The uncoated portion of the second electrode up to relative radius position 1 is divided into multiple segments, the height of which starts from the relative radius position R of the k@+1th winding turn. 2，k@+1 They are essentially the same up to the relative radius position 1.

[0066] In another aspect, in the winding structure of the first electrode, the uncoated portion bent in the radial direction of the electrode assembly is divided into multiple segments that can be bent independently. At least one of the height in the winding axis direction and the width in the winding direction of the multiple segments is gradually or gradually increased in stages along a direction parallel to the winding direction, either individually or in groups.

[0067] In another aspect, in the winding structure of the second electrode, the uncoated portion bent in the radial direction of the electrode assembly is divided into multiple segments that can be bent independently. At least one of the height in the winding axis direction and the width in the winding direction of the multiple segments is gradually or gradually increased in stages along a direction parallel to the winding direction, either individually or in groups.

[0068] In another side, multiple segments respectively satisfy at least one of the following conditions: a width condition of 1 mm to 11 mm in the winding direction; a height condition of 2 mm to 10 mm in the winding axis direction; and a separation spacing condition of 0.05 mm to 1 mm in the winding direction.

[0069] In another aspect, a cut-off groove is located between the aforementioned plurality of segments, and a predetermined gap is provided between the lower end of the cut-off groove and the active material layer of the first electrode or the second electrode.

[0070] On another side, the length of the aforementioned gap is 0.2 to 4 mm.

[0071] On another side, multiple strips are formed into multiple strip groups along the winding direction of the aforementioned electrode assembly. For strips belonging to the same strip group, at least one of the following is substantially the same: width in the winding direction, height in the winding axis direction, and separation distance in the winding direction.

[0072] In another aspect, for cut pieces belonging to the same cut piece group, as they approach a direction parallel to the winding direction of the aforementioned electrode assembly, at least one of the following—width in the winding direction, height in the winding axis direction, and separation spacing in the winding direction—gradually or progressively increases.

[0073] On another side, at least a portion of the multiple slit groups are configured on the same winding as the electrode assembly.

[0074] In another aspect, the bending surface region formed by the uncoated portion of the first electrode includes a layer number increasing interval and a layer number uniform interval from the outer periphery to the core of the electrode assembly. The layer number increasing interval is defined as the interval in which the layer number of the uncoated portion increases as it approaches the core of the electrode assembly. The layer number uniform interval is defined as the interval from the position where the layer number increase of the uncoated portion stops to the radius position where the uncoated portion begins to bend. The ratio of the radial length of the layer number uniform interval to the radial length from the winding loop where the uncoated portion begins to bend to the winding loop where the uncoated portion ends to bend is 30% or more.

[0075] In another aspect, the bending surface region formed by the uncoated portion of the second electrode extends from the outer periphery of the electrode assembly to the core side and includes a layer number increasing interval and a layer number uniform interval. The layer number increasing interval is defined as the interval from when the layer number of the uncoated portion increases from 1 to its maximum value. The layer number uniform interval is defined as the interval from the radius position where the layer number of the uncoated portion reaches its maximum value to the radius position where the uncoated portion begins to bend. The ratio of the radial length of the layer number uniform interval to the radial length from the starting bend of the uncoated portion to the ending bend of the uncoated portion is 30% or more.

[0076] In another aspect, the thickness of the first electrode and the second electrode is 80 μm to 250 μm, and the spacing between the uncoated portions of adjacent windings in the radial direction of the electrode assembly is 200 μm to 500 μm.

[0077] In another aspect, the thickness of the uncoated portion of the first electrode is 10 μm to 25 μm.

[0078] In another aspect, the thickness of the uncoated portion of the second electrode is 5 μm to 20 μm.

[0079] In another aspect, in a portion of the bent surface region formed by the uncoated portion of the first electrode, the total stack thickness of the overlapping layers of the uncoated portion is 100 μm to 975 μm.

[0080] In another aspect, the uncoated portion of the first electrode is divided into multiple segments that can be independently divided. The first electrode includes a height-variable range of segments with variable height and a height-uniform range of segments with uniform height. In the bending surface region, the segments included in the height-uniform range are bent along the radial direction of the component to form a region. The ratio of the uncoated portion stack thickness of the bending surface region to the height of the segments is 1.0% to 16.3%.

[0081] In another aspect, in a portion of the bent surface region formed by the uncoated portion of the second electrode, the total stack thickness of the overlapping layers of the uncoated portion is 50 μm to 780 μm.

[0082] In another aspect, the uncoated portion of the second electrode is divided into multiple segments that can be independently divided. The second electrode includes a height-variable range of segments with variable height and a height-uniform range of segments with uniform height. In the bending surface region, the segments included in the height-uniform range are bent along the radial direction of the assembly to form a region. The ratio of the uncoated portion stack thickness of the bending surface region to the height of the segments is 0.5% to 13.0%.

[0083] To address the aforementioned technical challenges, another aspect of the present invention provides an electrode assembly that defines a core and an outer peripheral surface by winding a first electrode, a second electrode, and a separation membrane between them around an axis. This electrode assembly is characterized in that the first electrode includes a first uncoated portion at its long side end that protrudes outside the separation membrane along the winding axis of the electrode assembly. A portion of the first uncoated portion is bent in the radial direction of the electrode assembly to form a first bent surface region. In a portion of the first bent surface region, the stack thickness of the first uncoated portion is between 100 μm and 975 μm.

[0084] In one side, the first uncoated portion of the first electrode is divided into a plurality of segments that can be independently divided into each other. The first electrode includes a height-variable range of segments with variable height and a height-uniform range of segments with uniform height. In the bending surface region, the segments included in the height-uniform range are bent along the radial direction of the component to form a region. The ratio of the uncoated portion stack thickness of the bending surface region to the height of the segments is 1.0% to 16.3%.

[0085] In another aspect, the second electrode includes a second uncoated portion at its long side end that protrudes to the outside of the separation membrane along the winding axis of the electrode assembly. A portion of the second uncoated portion is bent in the radial direction of the electrode assembly to form a second bent surface region. In a portion of the second bent surface region, the stacking thickness of the second uncoated portion is 50 μm to 780 μm.

[0086] In another aspect, the second uncoated portion of the second electrode is divided into multiple segments that can be independently divided. The second electrode includes a height-variable range of segments with variable height and a height-uniform range of segments with uniform height. In the bending surface region, the segments included in the height-uniform range are bent along the radial direction of the assembly to form a region. The ratio of the uncoated portion stack thickness in the bending surface region to the height of the segments is 0.5% to 13.0%.

[0087] To achieve the aforementioned technical challenges, another aspect of the battery of the present invention includes: an electrode assembly that defines a core and an outer peripheral surface by being wound around an axis with a first electrode, a second electrode, and a separator membrane between them. At least one of the first and second electrodes includes an uncoated portion at its long side end that protrudes beyond the separator membrane along the winding axis of the electrode assembly. At least a portion of the uncoated portion is bent in the radial direction of the electrode assembly to form a bent surface region. The number of layers of the uncoated portion in a portion of the bent surface region is 10 or more. The battery casing houses the electrode assembly and is electrically connected to one of the first and second electrodes, thus having a first polarity; a sealing body seals the open end of the battery casing; a terminal is electrically connected to the other of the first and second electrodes and has a second polarity with its surface exposed to the outside; and a current collector is welded to the bent surface area and electrically connected to either the battery casing or the terminal, wherein the welded area of ​​the current collector overlaps with the bent surface area where the number of layers of the uncoated portion is 10 or more.

[0088] In one side, the first electrode includes a first uncoated portion at its long side end that protrudes to the outside of the separation membrane along the winding axis direction of the electrode assembly. The total number of winding turns of the first electrode is defined as n1. The value obtained by dividing the winding turn index k at the k-th winding turn position by the total number of winding turns n1 is defined as the relative radius position R relative to the winding turn index k. 1，k At that time, relative to the relative radius position range where the first uncoated portion is bent, R satisfies the condition that the number of layers of the first uncoated portion is 10 or more. 1，k The length ratio of the radius direction interval is at least 30%, where k is a natural number from 1 to n1.

[0089] In another aspect, the second electrode includes a second uncoated portion at its long side end that protrudes to the outside of the separation membrane along the winding axis direction of the electrode assembly. The total number of winding turns of the second electrode is defined as n2, and the value obtained by dividing the winding turn index k at the k-th winding turn position by the total number of winding turns n2 is defined as the relative radius position R relative to the winding turn index k. 2，k At that time, relative to the relative radius position range where the second uncoated portion is bent, R satisfies the condition that the number of layers of the second uncoated portion is 10 or more. 2，k The length ratio of the radius direction interval is at least 30%, where k is a natural number from 1 to n².

[0090] In another aspect, the welding area of ​​the current collector overlaps by more than 50% with the bending surface area of ​​the uncoated part having a layer count of 10 or more.

[0091] In another aspect, the weld strength of the welded area of ​​the aforementioned current collector is 2 kgf / cm². 2 above.

[0092] To achieve the aforementioned technical challenges, another aspect of the battery of the present invention includes: an electrode assembly that defines a core and an outer peripheral surface by being wound around an axis with a first electrode, a second electrode, and a separating membrane between them; the first electrode having a first uncoated portion exposed to the outside of the separating membrane along the winding axis of the electrode assembly at its long side end; a portion of the first uncoated portion being bent in the radial direction of the electrode assembly to form a first bent surface region; the overlap thickness of the first uncoated portion in a portion of the first bent surface region being 100 μm to 975 μm; and a battery casing for housing the upper... The electrode assembly is electrically connected to one of the first electrode and the second electrode and has a first polarity; a sealing body seals the open end of the battery casing; a terminal is electrically connected to the other of the first electrode and the second electrode and has a second polarity exposed to the outside; and a first current collector is welded to the first bent surface area and electrically connected to either the battery casing or the terminal, wherein the welding area of ​​the first current collector overlaps with a portion of the first bent surface area, the first uncoated portion having a stack thickness of 100 μm to 975 μm.

[0093] In another aspect, the first uncoated portion of the first electrode is divided into multiple segments that can be independently divided. The first electrode includes a height-variable range of segments with variable height and a height-uniform range of segments with uniform height. In the first bending surface region, the segments included in the height-uniform range are bent along the radial direction of the component to form a region. The ratio of the uncoated portion stack thickness of the first bending surface region to the height of the segments is 1.0% to 16.3%.

[0094] In another aspect, the second electrode includes a second uncoated portion at its long side end that protrudes to the outside of the separation membrane along the winding axis of the electrode assembly. A portion of the second uncoated portion is bent in the radial direction of the electrode assembly to form a second bent surface region. The stack thickness of the second uncoated portion in a portion of the second bent surface region is 50 μm to 780 μm. The battery includes a second current collector that is soldered to the second bent surface region and electrically connected to another of the battery casing or the terminals. The soldering area of ​​the second current collector overlaps with a portion of the second bent surface region where the stack thickness of the second uncoated portion is 50 μm to 780 μm.

[0095] In another aspect, the second uncoated portion of the second electrode is divided into multiple segments that can be independently divided. The second electrode includes a height-variable range of segments with variable height and a height-uniform range of segments with uniform height. In the second bending surface region, the segments included in the height-uniform range are bent along the radial direction of the assembly to form a region. The ratio of the uncoated portion stack thickness of the second bending surface region to the height of the segments is 0.5% to 13.0%.

[0096] In another aspect, the welding area of ​​the first current collector overlaps by more than 50% with a portion of the first bent surface area of ​​the first uncoated portion, which has an overlap thickness of 100 μm to 975 μm.

[0097] In another aspect, the weld strength of the welded area of ​​the first current collector is 2 kgf / cm². 2 above.

[0098] In another aspect, the welding area of ​​the second current collector overlaps by more than 50% with a portion of the second bent surface area of ​​the second uncoated portion, which has an overlap thickness of 50 μm to 780 μm.

[0099] In another aspect, the weld strength of the welded area of ​​the second current collector is 2 kgf / cm². 2 above.

[0100] The aforementioned technical challenges can be achieved through a battery pack including the aforementioned battery and a vehicle including the battery pack.

[0101] Invention Effects

[0102] According to one aspect of the invention, when bending the uncoated portions exposed at both ends of the electrode assembly, it is possible to sufficiently ensure that more than 10 uncoated portions overlap in the radial direction of the electrode assembly, thereby preventing damage to the separation membrane or active material layer even when the welding power is increased.

[0103] According to another aspect of the invention, the structure of the uncoated portion adjacent to the core of the electrode assembly is improved, preventing the cavity in the core of the electrode assembly from being blocked when the uncoated portion is bent, and enabling easy electrolyte injection and welding of the battery casing and current collector.

[0104] According to another aspect of the invention, instead of strip-shaped electrode tabs, the bent surface area of ​​the uncoated portion is directly welded to the current collector, thereby providing an electrode assembly that increases energy density and reduces resistance.

[0105] According to another aspect of the present invention, it is possible to improve the structure of a battery having low internal resistance and improved welding strength of the current collector and uncoated portion, as well as the battery pack and automobile.

[0106] In addition, the present invention can achieve various other effects, which are described in the various embodiments, or the corresponding descriptions are omitted for effects that can be easily deduced by those skilled in the art. Attached Figure Description

[0107] Preferred embodiments of the invention are illustrated in the accompanying drawings, which serve to further explain the technical concept of the invention together with the detailed description of the invention that follows. Therefore, the invention should not be construed as being limited to the scope shown in these drawings.

[0108] Figure 1 This is a top view showing the electrode plate structure used in the manufacture of existing tabless cylindrical batteries.

[0109] Figure 2 This diagram illustrates the electrode plate winding process of a conventional tabless cylindrical battery.

[0110] Figure 3 The process of welding a current collector in the bent surface area of ​​the uncoated portion of a conventional tabless cylindrical battery is shown.

[0111] Figure 4 This is a top view showing the electrode plate structure according to a first embodiment of the present invention.

[0112] Figure 5 This is a diagram illustrating the definition of the width, height, and separation interval of a slice according to an embodiment of the present invention.

[0113] Figure 6 This is a diagram illustrating the overlapping conditions of the slices in an embodiment of the present invention.

[0114] Figure 7a and Figure 7b These are diagrams showing the upper and lower cross-sectional structures of the electrode assembly before the bending structure of the uncoated portion is formed according to an embodiment of the present invention.

[0115] Figure 8a and Figure 8b These are, respectively, a cross-sectional view and a perspective view of an electrode assembly formed by bending an uncoated portion to create a bent surface region according to an embodiment of the present invention.

[0116] Figure 9a This is a cross-sectional view of the bent surface region formed when the segments of the first electrode are bent from the outer periphery to the core side without overlapping in the circumferential direction in an electrode assembly including a cylindrical battery with a shape factor of 4680 and a radius of 22 mm.

[0117] Figure 9b This is a cross-sectional view showing the bent surface region formed by overlapping the segments of the first electrode in the radial and circumferential directions when the segments are bent from the outer periphery to the core side in an electrode assembly including a cylindrical battery with a shape factor of 4680 and a radius of 22 mm.

[0118] Figure 10 This is a cross-sectional view of a cylindrical battery cut along the Y-axis according to an embodiment of the present invention.

[0119] Figure 11 This is a cross-sectional view of a cylindrical battery cut along the Y-axis according to another embodiment of the present invention.

[0120] Figure 12 This is a top view showing the structure of the first current collector according to an embodiment of the present invention.

[0121] Figure 13 This is a perspective view showing the structure of the second current collector according to an embodiment of the present invention.

[0122] Figure 14 This is a top view showing the state in which multiple cylindrical batteries are electrically connected according to an embodiment of the present invention.

[0123] Figure 15 Is Figure 14 The image shows a detailed enlarged top view of the electrical connections of multiple cylindrical batteries.

[0124] Figure 16 This is a diagram illustrating a battery pack including a cylindrical battery according to an embodiment of the present invention.

[0125] Figure 17 This is a diagram illustrating a car that includes a battery pack according to an embodiment of the present invention. Detailed Implementation

[0126] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Before proceeding, the terms and words used in this specification and claims should not be limited to their ordinary or dictionary meanings. Given the principle that inventors may appropriately define terms and concepts in order to best illustrate their invention, they should be interpreted as meanings and concepts consistent with the technical concept of the present invention.

[0127] Therefore, the embodiments described in this specification and the configuration shown in the accompanying drawings are only one of the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. It should be understood that at the time of filing this application, there may be various equivalents and multiple modifications that can replace these.

[0128] First, an electrode assembly according to an embodiment of the present invention will be described. The electrode assembly may be a gel roll type electrode assembly having a first electrode in a sheet shape, a second electrode, and a separation membrane sandwiched between them, wound around a central axis. However, the present invention is not limited to a specific type of electrode assembly; therefore, the described electrode assembly may have any winding structure known in the art.

[0129] Preferably, at least one of the first electrode and the second electrode includes an uncoated portion at the long side end in the winding direction that is not coated with active material. At least a portion of the uncoated portion is used as an electrode tab in itself.

[0130] Figure 4 This is a top view showing the structure of the electrode 40 according to an embodiment of the present invention.

[0131] Reference Figure 4The electrode 40 includes a current collector 41 made of metal foil and an active material layer 42. The metal foil is made of aluminum or copper, appropriately selected according to the polarity of the electrode 40. The active material layer 42 is formed on at least one side of the current collector 41, and includes an uncoated portion 43 at the long side end in the winding direction X. The uncoated portion 43 is the area where no active material is coated. An insulating coating 44 is formed at the boundary between the active material layer 42 and the uncoated portion 43. At least a portion of the insulating coating 44 overlaps with the boundary between the active material layer 42 and the uncoated portion 43. The insulating coating 44 includes a polymer resin and includes an inorganic filter such as Al2O3. The region of the uncoated portion 43 where the insulating coating 44 is formed also lacks the active material layer 42, and is therefore equivalent to the uncoated portion 43.

[0132] Preferably, the bent portion in the uncoated portion 43 of the electrode 40 includes a plurality of segments 61. The plurality of segments 61 increase in height in stages from the core side toward the outer periphery side. The area in which the height increases in stages is the remaining area excluding the uncoated portion region adjacent to the core side of the electrode assembly (core-side uncoated portion A). Preferably, the height of the core-side uncoated portion A is relatively lower than that of the other portions.

[0133] The cut piece 61 can be obtained by laser engraving. The cut piece 61 can be formed by known metal foil cutting processes such as ultrasonic cutting or trimming.

[0134] When the electrode 40 is wound up, each piece 61 bends at the bending line 62 in the radial direction of the electrode assembly, for example, towards the core side. The core refers to the cavity located at the winding center of the electrode assembly. Each piece 61 has a geometric shape with the bending line 62 as its base. In the geometric shape, the width of the lower part is greater than the width of the upper part. In addition, in the geometric shape, the width of the lower part gradually or stepwise (not shown) increases towards the upper part. Preferably, the geometric shape is trapezoidal.

[0135] In variations, the geometric figure has at least one straight line, at least one curve, or a combination thereof. In one example, the geometric figure is a polygon such as a triangle, quadrilateral, or parallelogram. In another example, the geometric figure has an arc shape such as a semicircle or semi-ellipse.

[0136] When bending the cut piece 61, in order to prevent damage to the active material layer 42 and / or the insulating coating 44, it is preferable to bend the cut piece 61 at the lower end of the cut groove between the cut pieces 61. Figure 5A predetermined gap is maintained between the portion referred to as D4 and the active material layer 42. This is because stress concentrates around the lower end of the cut groove when the uncoated portion 43 is bent. The gap is preferably 0.2 to 4 mm. When the gap is adjusted to this range, damage to the active material layer 42 and / or the insulating coating 44 around the lower end of the cut groove due to stress generated during the bending process of the cut piece 61 can be prevented. In addition, the gap can prevent damage to the active material layer 42 and / or the insulating coating 44 caused by indentations or cutting tolerances of the cut piece 61.

[0137] Multiple segments 61 are arranged into multiple segments groups as they move from the core side to the outer periphery. Segments belonging to the same segment group have substantially the same width, height, and spacing.

[0138] Figure 5 This is a diagram illustrating the definition of the width, height, and spacing of the cutout 61 in an embodiment of the present invention.

[0139] Reference Figure 5 A cut-off groove 63 is formed between the segments 61. The lower corner portion of the cut-off groove 63 has a chamfered shape. That is, the cut-off groove 63 includes a substantially straight bottom 63a and a chamfered portion 63c. The chamfered portion 63c connects the bottom 63a and the side 63b of the segment 61. In a modified example, the bottom 63a of the cut-off groove 63 can be replaced with an arc shape. In this case, the side 63b of the segment 61 can be smoothly connected by the arc shape of the bottom 63a.

[0140] Preferably, the radius of curvature of the chamfered portion 63c is greater than 0 and less than 0.5 mm, more preferably greater than 0 and less than 0.1 mm. Even more preferably, the chamfered portion 63c may have a radius of curvature of 0.01 mm to 0.05 mm. When the radius of curvature of the chamfered portion 63c meets the above-mentioned numerical range, cracks can be prevented from appearing at the lower part of the cut-off groove 63 during the travel of the electrode 60 in the winding process or the like.

[0141] To prevent the uncoated portion 43 from tearing during bending and to improve welding strength, the width D, height H, and separation interval P of the cut piece 61 are designed to sufficiently increase the number of overlapping layers of the uncoated portion 43 and to prevent abnormal deformation of the uncoated portion 43. Abnormal deformation refers to the uncoated portion at the bottom of the bent section sinking and deforming irregularly instead of maintaining a straight line. The bent section is the portion that separates from the lower end of the cut groove 63 indicated by D4 by 2 mm or less, preferably by 1 mm or less.

[0142] The width D1 of the segment 61 is defined as the length between the two points where two straight lines extending from the two side edges 63b of the segment 61 intersect and a straight line extending from the bottom 63a of the cut-off groove 63. The height of the segment 61 is defined as the shortest distance between the uppermost edge of the segment 61 and the straight line extending from the bottom 63a of the cut-off groove 63. The spacing D3 of the segments 61 is defined as the length between the two points where a straight line extending from the bottom 63a of the cut-off groove 63 intersects and a straight line extending from the two side walls 63b connected to the bottom 63a. When the side edges 63b and / or the bottom 63a are curved, the straight lines can be replaced by lines extending from the side edges 63b and / or the bottom 63a.

[0143] Preferably, the width D1 of the cut piece 61 can be adjusted within the range of 1 mm to 11 mm. When D1 is less than 1 mm, when the cut piece 61 is bent towards the core side, areas that do not overlap sufficiently to ensure welding strength or empty spaces (gaps) may occur. Conversely, when D1 exceeds 11 mm, when the cut piece 61 is bent, the uncoated portion 43 around the bending portion D4 may be torn due to stress. The bending portion D4 separates from the bottom 63a of the cutting groove 63. The separation distance is 2 mm or less, preferably 1 mm or less. In addition, the height of the cut piece 61 can be adjusted within the range of 2 mm to 10 mm. When D2 is less than 2 mm, when the cut piece 61 is bent towards the core side, areas that do not overlap sufficiently to ensure welding strength or empty spaces (gaps) may occur. Conversely, when D2 exceeds 10 mm, it is difficult to maintain the flatness of the uncoated portion uniformly in the winding direction X to manufacture the electrode plate. That is, the height of the uncoated portion becomes larger, resulting in undulations. Furthermore, the spacing D3 between the cut pieces 61 can be adjusted within the range of 0.05 mm to 1 mm. When D3 is less than 0.05 mm, stress occurs when the electrode 40 travels through processes such as winding, causing cracks to form on the uncoated portion 43 around the lower end of the cutting groove 63. Conversely, when D3 exceeds 1 mm, areas or gaps may occur where the cut pieces 61 do not overlap to a degree sufficient to ensure weld strength when bent.

[0144] On the other hand, when the current collector 41 of the electrode 40 is made of aluminum, it is preferable to set the separation distance D3 to 0.5 mm or more. When D3 is 0.5 mm or more, even if the electrode 40 travels at a speed of 100 mm / sec or more under a tension of 300 gf or more during a winding process or the like, it is possible to prevent cracks from forming at the lower part of the cut-off groove 63.

[0145] According to the experimental results, when the current collector 41 of the electrode 40 is an aluminum foil with a thickness of 15 μm and D3 is 0.5 mm or more, no cracks are generated in the lower part of the cut-off groove 63 when the electrode 40 moves under the above-mentioned walking conditions.

[0146] Referring again to 4, the width d of the uncoated portion A on the core side A It is designed to meet the condition that the core of the electrode assembly is not obscured by more than 90% when the cut piece 61 is bent toward the core side.

[0147] In one example, the width d of the uncoated portion A on the core side A The bending length increases proportionally to the bending length of section 61 in group 1. The bending length is equivalent to the length of the bending section ( Figure 4 The height of the section 61 is based on 62).

[0148] In a specific example, when using electrode 40 in the manufacture of an electrode assembly for a cylindrical battery with a form factor of 4680, the width d of the uncoated portion A on the core side is determined according to the diameter of the electrode assembly core. A Set to 180mm to 350mm.

[0149] Preferably, the width d of the uncoated portion A on the core side is... A The length L of the long side of electrode 40 e The ratio d A / L e The ratio ranges from 1% to 30%. In large cylindrical batteries with a diameter of approximately 46 mm, the length of the electrode 40 is 3000 mm to 5000 mm, which is quite long, allowing for a sufficiently long uncoated portion A on the core side. Cylindrical batteries with a form factor of 1865 or 2170 have electrode plates with lengths ranging from 600 mm to 1200 mm. In typical cylindrical batteries, it is difficult to achieve a ratio d... A / L e The design is for the numerical range described above.

[0150] In one embodiment, the width of each sliver group is designed to form the same winding loop for the electrode assembly.

[0151] In another embodiment, the width of each sliver group is designed to form multiple turns of the electrode assembly.

[0152] In one variation, the width and / or height and / or spacing of the segments 61 belonging to the same segment group gradually and / or periodically and / or irregularly increases or decreases within or between groups.

[0153] Groups 1 to 7 are merely examples of cutter groups. The number of groups and the number of cutters 61 included in each group can be adjusted to maximize stress dispersion during the bending process of the uncoated portion 43, fully ensure weld strength, minimize the gap between the sides 63b of the cutters 61, ensure that the cutters 61 do not have gaps between them, and overlap in multiple layers along the radial direction of the electrode assembly.

[0154] In one variation, a portion of the cut pieces can be removed. In this case, the height of the uncoated portion of the removed cut piece is the same as the height of the uncoated portion A on the core side.

[0155] Preferably, the electrode 40 is divided into a height variable range where the height of the slice 61 changes along the long side direction and a height uniform range where the height of the slice 61 is uniform.

[0156] In electrode 40, the height variable range corresponds to the ranges from group 1 to group 7, and the height uniform range is the range closer to the outer periphery than group 7.

[0157] In a specific example, the width d of the uncoated portion A on the core side A The width is 180~350mm. The ratio of the width of the uncoated core A to the width of group 1 is 35~55%. The ratio of the width of group 1 to the width of group 2 is 120~150%. The ratio of the width of group 2 to the width of group 3 is 110~135%. The ratio of the width of group 3 to the width of group 4 is 75~90%. The ratio of the width of group 4 to the width of group 5 is 120~150%. The ratio of the width of group 5 to the width of group 6 is 100~120%. The ratio of the width of group 6 to the width of group 7 is 90~120%.

[0158] The reason why the widths of groups 1 to 7 do not show a definite increasing or decreasing pattern is that the width of the cut pieces gradually increases from group 1 to group 7, but the number of cut pieces included in the group is limited to a predetermined quantity, and the thickness of electrode 40 varies depending on the winding direction X. Therefore, the number of cut pieces in a particular cut piece group can be reduced. Thus, the width of the group shows an irregular variation pattern from the core side to the outer periphery side, as illustrated above.

[0159] When the widths of three adjacent cut pieces in the radial direction of the electrode assembly are set to W1, W2 and W3 respectively in the winding direction, the combination of cut pieces where W3 / W2 is smaller than W2 / W1 is included.

[0160] In the specific example above, groups 4 to 6 are equivalent to this. The width ratio of group 5 relative to group 4 is 120-150%, and the width ratio of group 6 relative to group 5 is 100-120%, with values ​​less than or equal to 120-150%.

[0161] Preferably, the lower interior angle θ of the plurality of segments 61 increases as they move from the core side to the outer periphery. The lower interior angle θ corresponds to the bend line ( Figure 4 The angle between the straight line of section 62) and the straight line (or connection) extending from the side 63b of section 61. In the case that section 61 is asymmetrical, the left interior angle and the right interior angle are different from each other.

[0162] As the radius of the electrode assembly increases, the radius of curvature also increases. When the lower interior angle θ of the piece 61 increases along with the radius of the electrode assembly, the stress generated in the radial and circumferential directions can be alleviated when the piece 61 is bent. In addition, as the lower interior angle θ increases, the area overlapping with the inner piece 61 and the number of layers of the piece 61 also increase when the piece 61 is bent, thereby ensuring uniform welding strength in the radial and circumferential directions and forming a flat bending surface area.

[0163] Preferably, as the radius of the electrode assembly increases, when the lower inner angle θ is adjusted, the cut piece 61 overlaps not only in the radial direction of the electrode assembly but also in the circumferential direction when it is bent.

[0164] Figure 6 (a) and (b) show examples where the sides of the segments 61 bent toward the core of the electrode assembly are parallel to each other and where the sides of the bent segments 61 intersect each other, respectively, in any winding loop with radius r and reference to the core center.

[0165] Reference Figure 6 With the core center O of the electrode assembly as a reference, a pair of segments 61 are arranged adjacent to a winding coil of radius r. The width and height of the adjacent segments 61 are substantially the same.

[0166] exist Figure 6 In (a), the lower interior angle θ assumption This is the angle assuming the sides of slice 61 are substantially parallel. Lower interior angle θ assumption It is based on the arc length L corresponding to the lower part of the section 61. arc And the angle that can be fixed. Conversely, θ real It is the actual lower interior angle when the sides of adjacent segments 61 intersect each other.

[0167] Preferably, the lower interior angle θ assumption and θ real When the following mathematical formula 1 is satisfied, with the core center O as the reference, the segments 61 arranged to be located on the winding loop at radius r overlap each other in the circumferential direction:

[0168] <Mathematical Formula 1>

[0169] θ real >θ assumption

[0170] θ assumption =90°-360° (L) arc / 2πr) 0.5

[0171] θreal >90°-360° (L) arc / 2πr) 0.5.

[0172] Here, r is the radius of the winding loop of the slice 61, which is configured with the core center of the electrode assembly as a reference.

[0173] L arc It is the length of the arc (implementation) in a circle with radius r that corresponds to the lower part (dashed line) of the slice, which is fixed based on the width D1 of slice 61.

[0174] '360° (L) arc / 2πr)' is the inscribed angle α of the arc (solid line) corresponding to the lower part (dashed line) of segment 61.

[0175] '360° (L) arc / 2πr) The angle between line segments OB and OA in right triangle OAB at 0.5'.

[0176] '90°-360° (L) arc / 2πr) 0.5' is the angle between line segments OA and AB in right triangle OAB, and the lower interior angle θ of segment 61. assumption Similarly, they correspond.

[0177] Preferably, in any winding radius r, L arc The circumferential angle α is less than 45°. When the circumferential angle α exceeds 45°, the bending of the section 61 cannot be achieved well. Therefore, in any radius r, L arc It is greater than the lower limit of D1, which is 1mm, and has (45 / 360). Lengths below (2πr).

[0178] The circumferential angle α varies depending on the radius of the winding loop in which the piece 61 is located. On one side, the circumferential angle α of the piece 61 satisfies the aforementioned numerical range, gradually or intermittently increasing, or vice versa, along the radial direction of the electrode assembly. On another side, the circumferential angle α of the piece 61 satisfies the aforementioned numerical range, gradually or intermittently increasing, or gradually or intermittently decreasing, or vice versa, along the radial direction of the electrode assembly. On yet another side, the circumferential angle α of the piece 61 satisfies the aforementioned numerical range and remains substantially the same along the radial direction of the electrode assembly.

[0179] Preferably, when the winding direction width D1 of the cut piece 61 varies along the winding direction, the circumferential angle α of the cut piece 61 is less than 45 degrees, and the winding direction width D1 of the cut piece 61 is in the range of 1m to 11mm.

[0180] In one example, when r is 20 mm and the circumferential angle α is 30°, L arc It is 10.5mm, θ assumption It is approximately 75 degrees. As another example, when r is 25 mm and the circumferential angle α is 25°, L... arc It is 10.9 mm, θ assumption It is approximately 77.5 degrees.

[0181] Preferably, in any winding radius r, θ real / θ assumption -1 is defined as the overlap rate of the slice 61 in the circumferential direction. The overlap rate of the slice 61 is preferably greater than 0 and less than 0.05. θ assumption It passes through the arc L within the radius r of the winding loop. arc The angle is fixed. When the overlap rate of the cut piece 61 is greater than 0.05, the sides interfere with each other and cannot be bent well when bending the cut piece 61.

[0182] The degree of overlap of the segments 61 increases proportionally to the overlap rate. When the segments 61 overlap each other along the circumferential direction of the winding loop, the number of layers of the segments 61 is further increased when bending the segments 61. An embodiment of this will be described later.

[0183] Preferably, when manufacturing an electrode assembly for a cylindrical battery with a shape factor of 4680, the electrode 40 is used, the radius of the core is 4 mm, and the height of the segment closest to the core is 3 mm. When the radius of the electrode assembly increases from 7 mm to 22 mm, the lower inner angle of the segment 61 is increased in stages in the range of 60 degrees to 85 degrees.

[0184] The aforementioned radius range and lower interior angle range are determined based on the shape factor and the diameter of the core, the height of the section closest to the core, the width D1 of section 61, and the design shape of the overlap ratio.

[0185] On the other hand, the conditions for overlapping cuts can be changed as follows. That is, as... Figure 6 As shown in (b), when drawing a hypothetical circle passing through a pair of adjacent segments 61 with the core center O of the electrode assembly 40 as a reference, the arc e passing through each segment... 1- e2 and e 3- When e4 overlaps, adjacent pairs of segments 61 overlap. The overlap rate of segment 61 is defined as the overlapping arc e when multiple hypothetical circles with different radii are drawn. 2- e3 and arc e 1-e2 or e 3- The maximum value among the length ratios of e4. The overlap rate of slice 61 is greater than 0 and less than 0.05.

[0186] The shape of the segment 61 changes depending on its location. In one example, areas with concentrated stress are suitable for chamfered shapes that facilitate stress dispersion (e.g., semicircles, semi-ellipses, etc.), while areas with relatively low stress are suitable for polygonal shapes (e.g., quadrilaterals, trapezoids, parallelograms, etc.).

[0187] The uncoated portion slitting structure can also be applied to the uncoated core portion A. However, when the slitting structure is applied to the uncoated core portion A, a reverse forming phenomenon can occur when the cut piece is bent according to the radius of curvature of the core, causing the end of the uncoated core portion A to twist outwards. Therefore, the slitting structure is not suitable for the uncoated core portion A. Even if the slitting structure is applied, considering the radius of curvature of the core, it is preferable to adjust the width and / or height and / or spacing of the cut piece 61 to a level that prevents reverse forming.

[0188] The electrode plate structure of the above-described embodiments (modified examples) can be applied to a first electrode and / or a second electrode of different polarities included in a gel roll-type electrode assembly. Furthermore, if the electrode structure of the embodiments (modified examples) is applied to either the first or second electrode, a conventional electrode plate structure can be applied to the other electrode. Moreover, the electrode plate structures applied to the first and second electrodes can be different and not identical to each other.

[0189] As an example, when the first electrode and the second electrode are respectively the anode and the cathode, any one of the embodiments (modified examples) can be used in the first electrode, and an existing electrode structure (see reference) can be used in the second electrode. Figure 1 ).

[0190] As another example, when the first electrode and the second electrode are the anode and the cathode, respectively, any one of the embodiments (modified examples) can be selectively applied to the first electrode, and any one of the embodiments (modified examples) can be selectively applied to the second electrode.

[0191] In this invention, the anodic active material coated on the anode and the cathode active material coated on the cathode can be any active material known in the art, without limitation.

[0192] In one example, the anolyte may include a material with the general chemical formula A[A] x M y O 2+zThe represented alkali metal compound (A includes at least one or more elements of Li, Na, and K; M includes at least one or more elements 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; the stoichiometric coefficients x, y, and z are selected in such a way that the compound maintains electrical neutrality).

[0193] In another example, the anode active material can be an alkali metal compound xLiM disclosed in US6,677,082, US6,680,143, etc. 1 O2(1 - x)Li2M 2 O3(M 1 includes at least one or more elements having an average oxidation state of 3; M 2 includes at least one or more elements having an average oxidation state of 4; 0≤x≤1).

[0194] In yet another example, the anode active material can be a general chemical formula LiaM 1 x Fe 1x M 2 yP 1y M 3 zO 4z (M 1 includes at least one or more elements selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg, and Al; M 2 includes at least one or more elements selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg, Al, As, Sb, Si, Ge, V, and S; M 3 includes halogen elements selectively including F; 0 < a≤2, 0≤x≤1, 0≤y < 1, 0≤z < 1; the stoichiometric coefficients a, x, y, and z are selected in such a way that the compound maintains electrical neutrality) or lithium metal phosphate represented by Li3M2(PO4)3 [M includes at least one element selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Al, Mg, and Al].

[0195] Preferably, the anode active material can include primary particles and / or secondary particles aggregated from primary particles.

[0196] In one example, the cathode active material can be carbon, lithium metal or lithium metal compounds, silicon or silicon compounds, tin or tin compounds, etc. Metal oxides such as TiO2 and SnO2 with a potential less than 2V can also be used as cathode active materials. Low-crystallinity carbon and high-crystallinity carbon can be used as carbon materials.

[0197] The separation membrane can be a porous polymer film, such as a porous polymer film made of polyolefin polymers such as ethylene monomer polymers, propylene monomer polymers, ethylene / butene copolymers, ethylene / hexene copolymers, and ethylene / methacrylate copolymers, or they can be used in layers. As another example, the separation membrane can be made of common porous nonwoven fabrics, such as nonwoven fabrics made of high-melting-point glass fibers or polyethylene terephthalate fibers.

[0198] At least one surface of the separation membrane may include a coating of inorganic particles. Furthermore, the separation membrane itself may be composed of a coating of inorganic particles. The particles constituting the coating may have a structure bonded to a binder to create an interstitial volume between adjacent particles.

[0199] Inorganic particles can be composed of inorganic materials with a dielectric constant of 5 or higher. As a non-limiting example, the aforementioned inorganic particles may include those selected from Pb(Zr,Ti)O3 (PZT), Pb... 1x La x Zr 1y Ti y O3 (PLZT), PB (Mg3Nb) 2 / 3 At least one substance in the group consisting of O3PbTiO3 (PMNPT), BaTiO3, hafnia (HfO2), SrTiO3, TiO2, Al2O3, ZrO2, SnO2, CeO2, MgO, CaO, ZnO and Y2O3.

[0200] The electrode assembly of this embodiment is a gel roll type electrode assembly 80 that applies the electrode 40 of this embodiment to the first electrode (anode) and the second electrode (cathode). However, the present invention is not limited to the specific type of electrode assembly.

[0201] Figure 7a and Figure 7b The upper and lower cross-sectional structures of the electrode assembly 80 before the bending structure of the uncoated portions 43a and 43a' is formed according to an embodiment of the present invention are shown respectively. Additionally, Figure 8a and Figure 8b These are cross-sectional and perspective views of an electrode assembly 80 formed by bending uncoated portions 43a and 43a' to create a bent surface region F according to embodiments of the present invention.

[0202] Electrode assembly 80 through Figure 2 The membrane is manufactured using the winding process described herein. For ease of explanation, the protruding structures of the uncoated portions 43a and 43a' extending outward from the separation membrane are shown in detail, while detailed illustrations of the winding structure of the separation membrane are omitted. The uncoated portion 43a protruding towards the upper part of the electrode assembly 80 extends from the first electrode 40. The uncoated portion 43a' protruding towards the lower part of the electrode assembly 80 extends from the second electrode 40'. The end positions of the separation membrane are shown by dashed lines.

[0203] A schematic illustration shows the pattern of varying heights of the uncoated portions 43a and 43a'. That is, the heights of the uncoated portions 43a and 43a' vary irregularly depending on the position of the cut section. For example, when the side of the trapezoidal segment 61 is cut, the height of the uncoated portion on the cut section is lower than the height of the segment 61. Figure 4 D2). Additionally, the cut-off slot ( Figure 5 63) The uncoated portions 43a and 43a' on the cut-off parts are not shown.

[0204] Hereinafter, with reference to the accompanying drawings, the structural features of the uncoated portion 43a of the first electrode 40 will be described in detail. Preferably, the uncoated portion 43a' of the second electrode 40' also has substantially the same features as the uncoated portion 43a of the first electrode 40.

[0205] Reference Figure 7a , Figure 7b , Figure 8a and Figure 8b The uncoated portions 43a and 43a' of the first electrode 40 and the second electrode 40' are bent in the radial direction to form a bent surface region F.

[0206] In the winding structure of the first electrode 40, when the total number of winding turns of the first electrode 40 is set to n1, the winding turn index k (a natural number from 1 to n1) of the kth winding turn is divided by the total number of winding turns n. 1而 The value of the operation is defined as the relative radius position R of the k-th winding loop. 1，k For the uncoated portion 43a, the number of layers is 10 or more at the radius position R. 1，k The ratio of the radial length of the interval to the radial length of the winding including the slice is 30% or more.

[0207] For reference, since the winding number index is 1, the relative radius position of the first winding is 1 / n1. The relative radius position of the kth winding is k / n1. The relative radius position of the final n1th winding is 1. That is, the relative radius position increases from 1 / n1 to 1 from the core side of the electrode assembly 80 to the outer periphery.

[0208] In the winding structure of the second electrode 40', when the total number of winding turns of the second electrode 40' is set to n2, the value obtained by dividing the winding turn index k (a natural number from 1 to n2) by the total number of winding turns n2 at the k-th winding turn position is defined as the relative radius position R of the k-th winding turn. 2，k At that time, the relative radius position R of the uncoated bending part has a layer count of 10 or more. 2，k The ratio of the radial length of the interval to the radial length of the winding ring with the cut pieces is more than 30%.

[0209] For reference, since the winding number index is 1, the relative radius position of the first winding is 1 / n². The relative radius position of the kth winding is k / n². The relative radius position of the last n²th winding is 1. That is, the relative radius position increases from 1 / n² to 1 from the core side of the electrode assembly 80 to the outer periphery.

[0210] Preferably, the winding number index k of the first electrode 40 and the second electrode 40' should be understood as a variable that can be assigned different values ​​to each other.

[0211] When the uncoated portions 43a and 43a' are bent in the radial direction, such as Figure 8a and Figure 8b As shown in the figure, bent surface regions F are formed on the upper and lower parts of the electrode assembly 80.

[0212] Reference Figure 8a and Figure 8b Multiple segments 61 are bent toward the core C side of the electrode assembly 80 and overlapped in multiple layers along the radial direction.

[0213] The number of layers of the cut piece 61 is defined as the number of cut pieces 61 that intersect the assumed line when a hypothetical line is drawn at any radius on the bending surface region F in the winding axis direction Y.

[0214] Preferably, regarding the number of layers of the cut sheet 61, in order to sufficiently increase the welding strength between the bending surface area F and the current collector and to prevent damage to the separation membrane and active material layer during the welding process, the number of layers is 10 or more in a radius range of at least 30% or more, based on the radial length R1 of the winding loop including the cut sheet 61.

[0215] The current collector is laser-welded to the bent surface area F of the uncoated portions 43a and 43'a. As a countermeasure, other known welding techniques such as resistance welding can be used. When laser welding is applied, it is preferable to increase the laser power to ensure sufficient weld strength. When the laser power is increased, the laser penetrates through the overlapping area of ​​the uncoated portions 43a and 43a' and into the interior of the electrode assembly 80, thereby damaging the separation membrane, active material layer, etc. Therefore, to prevent laser penetration, it is preferable to increase the number of overlapping layers of the uncoated portions 43a and 43a' in the welding area to a certain extent. To increase the number of overlapping layers of the uncoated portions 43a and 43a', it is necessary to increase the height of the cut-off piece 61. However, when the height of the cut-off piece 61 is increased, undulations occur in the uncoated portions 43a and 43a' during the manufacturing process of the electrode 40. Therefore, the height of the cut-off piece 61 is preferably adjusted to an appropriate level, preferably between 2 mm and 10 mm.

[0216] In the bending surface region F, the radius of the area where the number of stacked pieces 61 is 10 or more is designed to be 30% or more relative to R1. When laser welding is performed on the area where 10 or more stacked pieces 61 are overlapped and the current collector, even with increased laser power, the overlapping parts of the uncoated portion sufficiently block the laser, preventing damage to the separation membrane and active material layer caused by the laser. Furthermore, the large number of stacked pieces 61 in the laser-irradiated area results in sufficient volume and thickness of the weld bead. Therefore, sufficient weld strength is ensured, and the resistance of the weld interface is reduced.

[0217] When welding the current collector, the laser power is determined based on the desired weld strength between the bent surface region F and the current collector. The weld strength increases proportionally to the number of layers of the uncoated portions 43a and 43a'. This is because the more layers of the uncoated portions 43a and 43a' are stacked, the larger the volume of the weld bead formed by the laser becomes.

[0218] Preferably, the welding strength is 2 kgf / cm. 2 The above is preferred, with 4 kgf / cm² being more ideal. 2 The above applies. When the welding strength meets the above-mentioned numerical range, even if significant vibration is applied to the electrode assembly 80 along the winding axis and / or radial direction, the physical properties of the weld interface will not decrease, and the weld volume is sufficient, thereby reducing the resistance of the weld interface. The power of the laser used to achieve the above-mentioned welding strength conditions varies depending on the laser device and can be appropriately adjusted within the range of 250W to 320W or within 40% to 100% of the maximum laser power specification.

[0219] Weld strength is defined as the tensile force per unit area of ​​the current collector when it begins to separate from the bent surface region F (kgf / cm²). 2Specifically, after the current collector is welded, tension is applied to it and gradually increased. When the tension is high, the uncoated portions 43a and 43a' begin to separate from the weld interface. At this point, the weld strength is calculated by dividing the tension applied to the current collector by the area of ​​the current collector.

[0220] Preferably, the first electrode 40 includes a current collector (foil) 41 and an active material coating 42 forming at least one side thereof. The thickness of the current collector 41 is 10 μm to 25 μm, and the spacing between adjacent windings of the electrode assembly 80 in the radial direction is 200 μm to 500 μm. Preferably, the current collector 41 is made of aluminum.

[0221] The second electrode 40' includes a current collector (foil) and an active material coating formed on at least one side thereof. The thickness of the current collector is 5 to 20 μm, and the spacing between adjacent windings in the radial direction of the electrode assembly 80 is 200 to 500 μm. The current collector is copper.

[0222] Reference Figure 4 , Figure 7a and Figure 7b In the winding structure of the first electrode 40, from the relative radius position R of the first electrode 40 1，1 To the preset first relative radius position R 1，k The height of the uncoated section up to this point is less than the number of winding turns k. +1 relative radius position R 1，k +1 The height of the uncoated portion up to relative radius position 1. From relative radius position R 1，1 To the preset first relative radius position R 1，k The height of the uncoated portion in the preceding section corresponds to the height of the uncoated portion A on the core side (see reference). Figure 4 ).

[0223] Preferably, in the winding structure of the first electrode 40, from the relative radius position R 1，1 To the first relative radius position R 1，k The height of the bent surface area F formed by the overlap of the uncoated portion of the previous section with the uncoated portion of the bent section is lower.

[0224] Preferably, in the winding structure of the first electrode 40, from the relative radius position R 1，1 To the first relative radius position R 1，k The uncoated portion in the preceding section does not bend toward the core of the electrode assembly 80.

[0225] Similar to the first electrode 40, in the winding structure of the second electrode 40', from the relative radius position R 2，1 To the preset first relative radius position R 2，k The height of the uncoated section up to this point is lower than the winding loop k. +1 relative radius position R 2，k +1 The height of the uncoated portion of the interval up to the relative radius position 1.

[0226] Additionally, from the relative radius position R 2，1 To the preset first relative radius position R 2，k Compared to the bent surface area F formed by the overlap of the uncoated portion of the bend and the remaining section, the height of the uncoated portion is lower.

[0227] Preferably, from the relative radius position R 2，1 To the first relative radius position R 2，k The uncoated portion of the section up to this point does not bend toward the core of the electrode assembly.

[0228] Preferably, in the winding structure of the second electrode 40', from the relative radius position R 2，1 To the first relative radius position R 2，k The height of the uncoated portion of the preceding section is lower than the relative radius position R. 2，k +1 The height of the uncoated portion up to the relative radius position 1, without bending towards the core.

[0229] In the winding structure of the first electrode 40, the relative radius position R 1，k +1 Uncoated part bending length fd 1，k +1 Relative radius position R 1，1 To relative radius position R 1，k The length in the radial direction is short. Therefore, the core C of the electrode assembly 80 is not located at the relative radial position R. 1，k +1 The bend in the uncoated portion 43a within the range of relative radius position 1 is shielded.

[0230] As a countermeasure, the core C of the electrode assembly 80 is positioned at their radius r c Based on the baseline, not more than 90% of the area is located at the relative radius position R.1，k +1 The bent portion of the uncoated portion 43a within the range of relative radius position 1 is shielded. That is, the core C is at least equivalent to 0 to 0.9r. c The radius range is not obscured by the bend of the uncoated part 43a.

[0231] Preferably, it is located at a relative radius position R 1，k +1 The bending length fd of the uncoated part 43a 1，k +1 The radius r of the core c and relative radius position R 1，k +1 The distance d separated from the center of core C 1，k +1 Satisfying the following mathematical expression 2:

[0232] <Mathematical Formula 2>

[0233] fd 1，k +1 +0.9 r c ≤d 1，k +1 .

[0234] Preferably, in the winding structure of the second electrode 40', the relative radius position R 2，1 To the first relative radius position R 2，k The height of the uncoated portion of the preceding section is lower than the relative radius position R. 2，k +1 The height of the uncoated portion within the range of relative radius position 1, without bending towards the core.

[0235] In the winding structure of the second electrode 40', located at the relative radius position R 2，k +1 The bending length fd of the uncoated part 2，k +1 Relative radius position R 2，1 To the first relative radius position R 2，k The length is short. Therefore, the core C of the electrode assembly 80 is not located at the relative radius position R. 2，k +1 The uncoated portion of the section within the relative radius position 1 is covered by the bend.

[0236] As a countermeasure, the core C of the electrode assembly 80 is positioned at their radius r c Based on the baseline, not more than 90% of the area is located at the relative radius position R. 2，k +1 The uncoated portion 43a' is covered by the bend.

[0237] Preferably, it is located at a relative radius position R 2，k +1 The bending length fd of the uncoated part 43a' 2，k +1 The radius r of the core c and relative radius position R 2，k +1 The distance d separated from the center of core C 2，k +1 Satisfying the following mathematical expression 3:

[0238] <Mathematical Formula 3>

[0239] fd 2，k +1 +0.9 r c ≤d 2，k +1 .

[0240] Preferably, in the winding structure of the first electrode 40, from the preset second relative radius position R of the k@+1th winding turn 1，k@+1 The uncoated portion of the first electrode 40 up to the relative radius position 1 is divided into multiple segments 61, the height of which varies from the relative radius position R. 1，k@+1 They are essentially the same up to the relative radius position 1.

[0241] On the other hand, in the winding structure of the first electrode 40, the relative radius position R 1，k +1 To the preset second relative radius position R of the k@th winding turn 1，k@ The uncoated portion 43a of the preceding section is divided into multiple segments 61, the height of which increases gradually or in stages towards the outer periphery. Therefore, from the relative radius position R... 1，k +1 To R 1，k@The interval up to that point is equivalent to a highly variable interval.

[0242] For example, in the winding structure of the first electrode 40 with a radius of 22 mm, the radial length of the variable height range of the cut piece is defined as H1, and H1 is compared with the radius Rr of the winding structure of the first electrode 40 excluding the core C. c The ratio is defined as the highly variable range ratio H1 / Rr. c When the height variable interval ratio is rounded to the nearest whole number, it is calculated as follows.

[0243] In Example 1, R is 22 mm, and the core radius r c It is 5mm, Rr c The height of the section 61 varies in eight stages, from a radius of 7mm to 15mm, and then to 2mm to 10mm. The height of the section 61 remains at 10mm after the radius of 15mm. H1 is 8mm, therefore the ratio of the variable height range is 47% (8mm / 17mm).

[0244] In Example 2, R and r c Same as Example 1. The height of the section 61 varies in seven stages, from a radius of 7 mm to 14 mm to 2 mm to 9 mm. After the radius of 14 mm, the height of the section 61 remains at 9 mm. H1 is 7 mm, so the ratio of the variable height range is 41% (7 mm / 17 mm).

[0245] In Example 3, R and r c Same as Example 1. The height of the section 61 varies in six stages, from a radius of 7 mm to 13 mm to 2 mm to 8 mm. After the radius of 13 mm, the height of the section 61 remains at 8 mm. H1 is 6 mm, so the ratio of the variable height range is 35% (6 mm / 17 mm).

[0246] In Example 4, R and r c Same as Example 1. The height of the section 61 varies in five stages, from a radius of 7 mm to 12 mm to 2 mm to 7 mm. After the radius of 12 mm, the height of the section 61 remains at 7 mm. H1 is 5 mm, so the ratio of the variable height range is 29% (5 mm / 17 mm).

[0247] In Example 5, R and r c Same as Example 1. The height of the section 61 varies in four stages, from a radius of 7 mm to 11 mm to a radius of 2 mm to 6 mm. After the radius of 11 mm, the height of the section 61 remains at 6 mm. H1 is 4 mm, so the ratio of the variable height range is 24% (4 mm / 17 mm).

[0248] In Example 6, R and r c Same as in Example 1. The height of the section 61 varies in three stages: from a radius of 7 mm to 10 mm, to a radius of 2 mm to 5 mm. After the radius of 10 mm, the height of the section 61 remains at 5 mm. H1 is 3 mm, so the ratio of the variable height range is 18% (3 mm / 17 mm).

[0249] In Example 7, R and r c Same as in Example 1. The height of the section 61 varies in two stages: from a radius of 7 mm to 9 mm to a radius of 2 mm to 4 mm. After the radius of 9 mm, the height of the section 61 remains at 4 mm. H1 is 2 mm, so the ratio of the variable height range is 12% (2 mm / 17 mm).

[0250] In Example 8, R and r c Same as in Example 1. The height of the section 61 changes in stages from a radius of 7 mm to 8 mm to a range of 2 mm to 3 mm. After the radius of 8 mm, the height of the section 61 remains at 3 mm. H1 is 1 mm, so the ratio of the variable height range is 6% (1 mm / 17 mm).

[0251] In summary, R is 22mm, r c When the radius is 5mm, the height of the section in the range of 7mm to 15mm varies from 2mm to 10mm to any one of the stages from stage 1 to stage 8, and the height variable range ratio is 6% to 47%.

[0252] The numerical range of the highly variable interval ratio depends on the radius r of the core C. c The value changes depending on the size. The calculation is similar to the above, so only the results are disclosed.

[0253] In one example, R is 22 mm, r c When the radius is 4mm, the height of the section in the range of 6mm to 14mm changes in stages from stage 1 to stage 8 in the range of 2mm to 10mm, and the ratio of the variable height range is 6% to 44%.

[0254] In another example, R is 22 mm, r c When the height of the section in the radius range of 5mm to 13mm is 3mm, and the height of the section changes in stages from 2mm to 10mm to any one of stages from stage 1 to stage 8, the ratio of the variable height range is 5% to 42%.

[0255] In yet another example, R is 22 mm, r cWhen the height of the section in the radius range of 4mm to 12mm is 2mm, and the height of the section changes in stages from stage 1 to stage 8 in the range of 2mm to 10mm, the ratio of the variable height range is 5% to 40%.

[0256] From the above calculation example, in the core C, the radius r c When varying within the range of 2mm to 5mm, the height variable range ratio is 5% to 47%. With a fixed radius of electrode assembly 80, the height varies with the radius r of the core C. c As the ratio of highly variable intervals decreases, both the lower and upper limits gradually decrease.

[0257] On the other hand, the upper and lower limits of the height variable interval ratio change according to the height change width and the number of height changes of the section 61 when the radius increases by 1 mm.

[0258] In one example, when the height of the slice 61 changes by 0.2 mm for every 1 mm increase in radius, the lower and upper limits of the ratio of the variable height range are 1% and 9%, respectively.

[0259] In another example, when the height of the section 61 changes by 1.2 mm for every 1 mm increase in radius, the lower and upper limits of the height variable range ratio are 6% and 56%, respectively.

[0260] As can be seen from the above examples, the height variable range ratio is preferably between 1% and 56%. When the height variable range ratio of the cut-off piece 61 meets the above numerical range, the ratio of the radial length of the uncoated portion 40 at the relative radial position where the number of layers is 10 or more is at least 30% relative to the radial length R1 of the winding including the cut-off piece 61. As will be described later, such a structure can improve useful effects on the welding strength and resistance of the current collector.

[0261] Re-reference Figure 4 and Figure 7b In the winding structure of the second electrode 40', the relative radius position R 2，k +1 To the preset second relative radius position R of the k@th winding turn 2，k@ The uncoated portion of the preceding section is divided into multiple segments 61, the height of which increases gradually or in stages towards the outer periphery. Therefore, from the relative radius position R... 2，k +1 To R 2，k@ The interval up to that point is equivalent to a highly variable interval.

[0262] In the winding structure of the second electrode 40', the radial length of the height-variable range is defined as H2, and H2 is interposed with the radius Rr of the winding structure of the second electrode 40' excluding the core C. c The ratio is defined as the highly variable range ratio H2 / (Rr) c When the highly variable range ratio is used, it is preferably 1% to 56%, similar to that of the first electrode.

[0263] When the ratio of the height variable interval of the slice 61 relative to the uncoated portion 43a' satisfies the above-mentioned numerical range, the ratio of the relative radius position of the uncoated portion 40 with a stack number of 10 or more sheets to the radial length R2 of the winding loop including the slice 61 is at least 30%.

[0264] In the winding structure of the second electrode 40', from the relative radius position R of the k@+1th winding turn 2，k@+1 The uncoated portion of the second electrode 40' up to the relative radius position 1 is divided into multiple segments 61, the height of which varies from the relative radius position R. 2，k@+1 They are essentially the same up to the relative radius position 1.

[0265] Preferably, in the winding structure of the first electrode 40, the uncoated portion 43a bent toward the core side is divided into a plurality of segments 61, and at least one of the height in the winding axis direction and the width in the winding direction of the plurality of segments 61 increases gradually or in stages, either individually or according to each group, as they move from the core side toward the outer periphery side.

[0266] Similarly, in the winding structure of the second electrode 40', the uncoated portion 43a' bent toward the core side is divided into a plurality of segments 61, and at least one of the height in the winding axis direction and the width in the winding direction of the plurality of segments 61 increases gradually or in stages, either individually or according to each group, as they move from the core side toward the outer periphery side.

[0267] Preferably, when the bent portions of the uncoated portions 43a and 43a' are divided into multiple segments 61, the multiple segments 61 respectively satisfy at least one of the following conditions: a width of 1 to 11 mm in the winding direction ( Figure 5 D1 condition; height of 2 to 10 mm in the winding axis direction ( Figure 5 The D2 condition; and the D3 condition of a separation distance of 0.05 to 1 mm in the winding direction.

[0268] Preferably, the bottom of the cutting groove of the cut piece 61 ( Figure 5 The portion referred to by D4 has a predetermined gap with the active material layer 42. Preferably, the gap is 0.2 to 4 mm.

[0269] Reference Figure 4When the bent portions of the uncoated portions 43a and 43a' are divided into multiple segments 61, the multiple segments 61 form multiple segments groups as they move from the core side to the outer periphery side. At least one of the following is the same for the segments belonging to the same segments group: width in the winding direction, height in the winding axis direction, and separation spacing in the winding direction.

[0270] Preferably, at least a portion of the plurality of cutter groups are arranged in the same winding coil as the electrode assembly 80. In one example, the cutters comprising each group form at least one winding coil in the winding structure of the electrode assembly 80. In another example, the cutters comprising each group form at least two winding coils in the winding structure of the electrode assembly 80.

[0271] Figure 9a The following is a partial cross-sectional view: In an electrode assembly with a radius of 22 mm in a cylindrical battery having a shape factor of 4680, the uncoated portion 43a of the first electrode 40, which is divided into multiple segments 61, is bent from the outer periphery to the core to form a bent surface region F. A portion of the bent surface region F is overlapped with more than 10 uncoated portions 43a along the radial direction, forming a layer number increasing interval and a layer number uniform interval along the radial direction of the electrode assembly 80.

[0272] Reference Figure 9a In the bending surface region F, the number of layers in the uncoated portion 43a increases from the outer periphery of the electrode assembly 80 towards the core side, and when the maximum value is reached, the maximum value is maintained within a specified radius range and decreases by 1 to 2 layers around the core.

[0273] Next, the radius range from which the number of layers in the uncoated portion 43a increases towards its maximum value from the outer periphery of the electrode assembly 80 towards the core is defined as the layer number increasing range. The range in which the number of layers in the uncoated portion 43a remains at its maximum value and the remaining range around the core are added together to define the layer number uniform range. The layer number uniform range includes the range in which the number of layers in the uncoated portion 43a remains at its maximum value, thus the bending surface region F is flatter than other parts, achieving the optimal welding area.

[0274] exist Figure 9a In the middle, the uncoated part 43a is as follows Figure 5 The section shown is divided into a trapezoidal shape. Only the upper part of the uncoated portion 43a is shown, with the bottom 63a of the cut-off groove 63 as a reference. The portion corresponding to the cross-section of the cut-off groove 63 is not shown as the uncoated portion 43a.

[0275] The actual bending points of the cut piece 61 are not entirely the same, and they are separated by a predetermined distance from the lower end of the cutting groove 63. As the number of overlaps of the uncoated portions 43a increases closer to the core side, resistance to overlap is generated. Therefore, it is preferable to bend at the point where the cut piece 61 is separated by a predetermined distance from the lower end of the cutting groove 63. The separation distance is 2 mm or less, preferably 1 mm or less. When a separation distance exists, the overlap of the cut pieces 61 can be performed more effectively in the radial direction.

[0276] The bent surface region F is formed by overlapping segments located on different winding loops in the radial direction of the electrode assembly 80. Figure 9a In the illustrated embodiment, the segments 61 do not overlap in the circumferential direction. That is, as shown... Figure 6 Thus, (a) there is a gap between the sides of the cut piece 61. The conditions for the existence of the gap can be adjusted by adjusting the width, height, spacing, and lower inner angle of the cut pieces. Regarding the bending surface area F when the cut pieces overlap in the circumferential direction, refer to Figure 9b Then it will be discussed.

[0277] In this embodiment, the radius r of the core of the electrode assembly 80 c The thickness is 4mm. Furthermore, the height of the cut-off piece begins at 3mm. Based on the radius of the electrode assembly, there are no cut-off pieces in the uncoated portion 43a up to 4mm and 7mm. That is, within the total radius of the electrode assembly (22mm), there are cut-off pieces in the range from 7mm to 22mm, and the width of the radius range containing the cut-off piece 61 is 15mm. If, based on the radius r of the core... c Based on this, if a maximum of 10% is obscured by the cut-off piece, the part where the cut-off piece is first configured will move towards the core side.

[0278] In the winding structure, a segment with a height of 3 mm is arranged starting from the winding coil at a position with an approximate radius of 7 mm. Starting from the radius of 7 mm of the winding structure, the height of the segment increases by 1 mm for every 1 mm increase in radius from the core side to the outer periphery side. The period of increase in segment height can be varied from 0.2 mm to 1.2 mm per unit radius (1 mm).

[0279] Figure 9a(a) represents the case where the maximum height of the cutter is 8 mm. In this case, the cutter is positioned with a radius of 7 mm from the center of the core. Only in this way can the cutter with a height of 3 mm not obstruct the core with a radius of 4 mm when bent towards the core. When the radius increases from 7 mm to 12 mm, the height of the cutter increases in 5 stages from 3 mm to 8 mm. In addition, the height of the cutter remains at 8 mm up to the radius of 12 mm to 22 mm. In this embodiment, the variable range of the cutter height is from a radius of 7 mm to 12 mm, and the variable height range ratio is 28% (5 / 18, rounded to the first decimal place, the same applies below).

[0280] Figure 9a (b) represents the case where the maximum height of the cutter is 7 mm. In this case, the cutter is positioned starting at a point where the radius of the electrode assembly becomes 7 mm from the center of the core. Only in this way can the cutter with a height of 3 mm not obstruct the core with a radius of 4 mm when bent towards the core. When the radius increases from 7 mm to 11 mm, the height of the cutter increases in four stages from 3 mm to 7 mm. Furthermore, when the radius is from 11 mm to 22 mm, the height of the cutter remains at 7 mm. In this embodiment, the variable range of the cutter height is from a radius of 7 mm to 11 mm, and the ratio of the variable height range is 22% (4 / 18).

[0281] Figure 9a (c) represents the case where the maximum height of the slice is 6 mm. In this case, the slice is positioned at a point with a radius of 7 mm from the center of the core. Only in this way can the 3 mm high slice not obstruct the 4 mm radius core when bent towards the core. When the radius increases from 7 mm to 10 mm, the slice height increases in three stages from 3 mm to 6 mm. Furthermore, when the radius is from 10 mm to 22 mm, the slice height remains at 6 mm. In this embodiment, the variable range of the slice height is from a radius of 7 mm to 10 mm, and the variable height range ratio is 17% (3 / 18).

[0282] exist Figure 9a In the embodiments shown in (a), (b), and (c), the variable height range of the slice begins with a radius of 7 mm. Furthermore, the ratio of the variable height range is 17% to 28%. Such a ratio range includes the aforementioned preferred range of 1% to 56%.

[0283] Reference Figure 9a As the number of layers in the uncoated portion 43a increases from the outer periphery towards the core, even though the minimum length of the cut piece is 3 mm, the maximum number of layers increases to 12, 15, and 18 as the maximum length of the cut piece increases to 6 mm, 7 mm, and 8 mm. Furthermore, the thickness of the bending surface region F increases proportionally to the number of layers.

[0284] As an example, when the maximum height of the cut piece is less than 8 mm, the number of layers in the uncoated portion 43a increases to 18 sheets within a 7 mm radius from the outer peripheral surface of the electrode assembly 80 towards the core. Within an 8 mm radius from the point where the increase in the number of layers stops, the number of layers in the uncoated portion 43a remains uniformly at 18 sheets. In this example, the number of layers in the uniform layer count range is at least 16 sheets, and the radial width is 8 mm. The ratio of the width of the uniform layer count range to the radial length of the winding loop including the cut piece (15 mm) is 53% (8 / 15, rounded to the nearest whole number, the same applies below).

[0285] As another example, when the maximum height of the cut piece is 7 mm, the number of layers in the uncoated portion 43a increases to 15 sheets within a 6 mm radius from the outer peripheral surface of the electrode assembly 80 towards the core. Within a 9 mm radius from the point where the increase in the number of layers stops, the number of layers in the uncoated portion 43a remains uniformly at 15 sheets. Therefore, the radial width of the uniform layer count interval is 9 mm, and the number of layers in the uniform layer count interval is at least 13 sheets. The ratio of the width of the uniform layer count interval to the radial length of the winding loop including the cut piece (15 mm) is 60% (9 / 15).

[0286] As another example, when the maximum height of the cut piece is less than 5 mm, the number of layers in the uncoated portion 43a increases to 12 sheets within a 5 mm radius from the outer peripheral surface of the electrode assembly 80 towards the core. Within a 10 mm radius from the point where the increase in the number of layers stops, the number of layers in the uncoated portion 43a remains uniformly at 12 sheets. Therefore, the radial width of the uniform layer count interval is 10 mm, and the number of layers within the uniform layer count interval is at least 11 sheets. The ratio of the width of the uniform layer count interval to the radial length of the winding loop including the cut piece (15 mm) is 67% (10 / 15).

[0287] According to the embodiments, when the minimum length of the cut piece is 3mm and the maximum length of the cut piece is 6mm, 7mm and 8mm, the length of the interval of increasing number of layers gradually increases to 5mm, 6mm and 7mm respectively, and the ratio of the uniform interval of 10 or more layers in the uncoated part 43a is 53% to 67%.

[0288] On the other hand, the thickness of the bent surface region F increases proportionally to the number of layers of the uncoated portion 43a. In the variable height range, depending on the minimum and maximum height of the cut piece, the number of layers of the uncoated portion 43a decreases to 10, thus the number of layers of the uncoated portion 43a is between 10 and 18. In one example, when the uncoated portion 43a is aluminum and its thickness is between 10 μm and 25 μm, the thickness of the bent surface region F is between 100 μm and 450 μm. In another example, when the uncoated portion 43a is copper and its thickness is between 5 μm and 20 μm, the thickness of the bent surface region F is between 50 μm and 360 μm. When the thickness of the bent surface region F meets the above-mentioned numerical range, when the current collector is welded to the bent surface region F using a laser, the bent surface region F sufficiently absorbs the laser energy. As a result, the weld bead in the bent surface region F is formed with sufficient volume, thereby increasing the weld strength. In addition, the welding area is perforated by laser to prevent damage to the separation membrane and other components located in the lower part of the bending surface area F.

[0289] Preferably, the current collector is welded to the bent surface region F. At least a portion of the welded region of the current collector overlaps with a uniformly stacked interval based on the radial direction.

[0290] Preferably, in the radial direction of the electrode assembly, 50% to 100% of the welding area of ​​the current collector overlaps with the uniform layer number interval. A higher overlap ratio of the welding area is more beneficial for improving welding strength and increasing weld volume. Within the welding area of ​​the current collector, the remaining area that does not overlap with the uniform layer number interval overlaps with the interval where the layer number increases.

[0291] On the other hand, refer to Figure 6 As explained, when the uncoated portion 43a is bent to form the bent surface region F, including when the lower inner angles of the pieces in each piece group satisfy the condition of Formula 1, the sides of adjacent pieces 61 located on the same winding loop intersect and overlap each other in the circumferential direction. In this case, the number of layers of the uncoated portion 43a in the radial direction of the electrode assembly is further increased.

[0292] Figure 9b This is an illustrative cross-sectional view of the bent surface region F, showing the intervals of increasing and uniform stacking numbers, when the slices are overlapped in the circumferential direction.

[0293] Reference Figure 9b From the outer periphery to the core, the number of overlaps in the uncoated portion 43a increases. The variable height range of the sectional section is related to... Figure 9aThe embodiments similarly start with a radius of 7 mm. The height of the slice starts at 3 mm, and increases by 1 mm for every 1 mm increase in radius. When the maximum slice height is increased to 6 mm, 7 mm, 8 mm, 9 mm, and 10 mm, the number of layers at the radius position starting from the uniform layer number interval increases to 18, 22, 26, 30, and 34, respectively. Under the same conditions where the maximum slice height is 6 mm, 7 mm, and 8 mm, the same as... Figure 9a Compared to the previous embodiment, the number of layers increases by 6 to 8. This is because the cuts are overlapped in the circumferential direction.

[0294] Specifically, when the maximum cut height is 10 mm, the number of layers in the uncoated portion 43a increases to 34 sheets in a 9 mm radius range from the outer peripheral surface of the electrode assembly 80 towards the core (the increasing layer count range). In a 6 mm radius range from the point where the increase in layer count stops, the number of layers in the uncoated portion 43a remains at 34 sheets. Then, the number of layers around the core further increases to 39 sheets. The increase in the number of layers around the core is because the overlap of the cut pieces in the circumferential direction increases as it approaches the core. In this example, the number of layers in the uniform layer count range is at least 34 sheets, and the radial width is 6 mm. The uniform layer count range starts at a radius of 7 mm and has a ratio of 40% (6 / 15, rounded to the first decimal place, the same applies below) to the radial length of the winding loop including the cut piece (15 mm).

[0295] As another example, when the maximum cut height is 9 mm, the number of layers in the uncoated portion 43a increases to 30 sheets in a radius of 8 mm from the outer peripheral surface of the electrode assembly 80 towards the core. In a radius of 7 mm from the point where the increase in the number of layers stops, the number of layers in the uncoated portion 43a remains at 30 sheets, and then further increases to 36 sheets around the core. Therefore, the radial width of the uniform layer count interval is 7 mm, and the number of layers in the uniform layer count interval is at least 30 sheets. The ratio of the uniform layer count interval starting from a radius of 7 mm to the radial length of the winding loop including the cut piece (15 mm) is 47% (7 / 15).

[0296] As another example, when the maximum height of the cut piece is less than 8 mm, the number of overlaps in the uncoated portion 43a increases to 26 sheets in a 7 mm radius section from the outer peripheral surface of the electrode assembly 80 towards the core. The number of overlaps in the uncoated portion 43a remains at 26 sheets in a 8 mm radius section from the radius where the increase in the number of overlaps stops, and then further increases to 28 sheets around the core. Therefore, the radial width of the uniform overlap range is 8 mm, and the number of overlaps in the uniform overlap range is at least 26 sheets. The ratio of the uniform overlap range starting from a radius of 7 mm to the radial length of the winding loop including the cut piece (15 mm) is 53% (8 / 15).

[0297] As another example, when the maximum height of the cut piece is less than 7 mm, the number of overlaps in the uncoated portion 43a increases to 22 sheets in a 6 mm radius range from the outer peripheral surface of the electrode assembly 80 towards the core. In a 9 mm radius range from the radius where the increase in the number of overlaps stops, the number of overlaps in the uncoated portion 43a remains at 22 sheets, and further increases to 23 sheets around the core. Therefore, the radial width of the uniform overlap range is 9 mm, and the number of overlaps in the uniform overlap range is at least 22 sheets. The uniform overlap range is a range starting from a radius of 7 mm, with a ratio of 60% (9 / 15) to the radial length of the winding loop including the cut piece (15 mm).

[0298] As another example, when the maximum cut height is 6 mm, the number of overlaps in the uncoated portion 43a increases to 18 sheets within a 5 mm radius from the outer peripheral surface of the electrode assembly 80 towards the core. Within a 10 mm radius from the point where the increase in the number of overlaps stops, the number of overlaps in the uncoated portion 43a remains at 18 sheets, and then further increases to 20 sheets around the core. Therefore, the radial width of the uniform overlap range is 10 mm, and the number of overlaps in the uniform overlap range is at least 18 sheets. The uniform overlap range starts from a radius of 7 mm and is 67% (10 / 15) of the radial length of the winding loop including the cut piece (15 mm).

[0299] according to Figure 9b The illustrated embodiments confirm that when the minimum cut height is 3m and the maximum cut height is 6mm, 7mm, 8mm, 9mm, and 10mm, the length of the interval for gradually increasing the number of layers increases to 5mm, 6mm, 7mm, 8mm, and 9mm. Furthermore, the percentage of uniform intervals with 10 or more layers is 40% to 67%.

[0300] On the other hand, Figure 9b In the embodiments, the thickness of the bent surface region F increases proportionally to the number of layers of the uncoated portion 43a. The number of layers of the uncoated portion 43a is 18 to 39. In one example, when the uncoated portion 43a is aluminum and its thickness is 10 μm to 25 μm, the thickness of the bent surface region F is 180 μm to 975 μm. In another example, when the uncoated portion 43a is copper and its thickness is 5 μm to 20 μm, the thickness of the bent surface region F is 90 μm to 780 μm. When the thickness of the bent surface region F meets the above-mentioned numerical range, when the current collector is welded to the bent surface region F using a laser, the bent surface region F sufficiently absorbs the laser energy. As a result, the weld bead in the bent surface region F is formed with sufficient volume, thereby increasing the weld strength. In addition, by perforating the welded area with a laser, damage to the separation membrane and the like located in the lower part of the bent surface region F is prevented.

[0301] Preferably, at least a portion of the welding area of ​​the current collector overlaps with the uniform layer number interval along the radial direction. More preferably, 50% to 100% of the welding area of ​​the current collector 80 along the radial direction overlaps with the uniform layer number interval. A higher overlap ratio of the welding area is more beneficial for improving welding strength. Within the welding area of ​​the current collector, areas that do not overlap with the uniform layer number interval overlap with intervals that increase the layer number.

[0302] Figure 9a and Figure 9b In the illustrated embodiment, those skilled in the art will understand that the uniformity range of the number of layers in the uncoated portion 43a depends on the radius R of the electrode assembly and the radius r of the core. c The minimum and maximum values ​​of the cut section height within the variable range, and the increase or decrease of the cut section height in the radial direction of the electrode assembly.

[0303] The ratio of uniformly stacked intervals to core r c The radius is inversely proportional. Furthermore, when the minimum height of the cut section is the same, the smaller the width of the height-variable section, the greater the increase in the ratio of uniform layer count intervals. Also, when the maximum height of the cut section is the same, the smaller the width of the height-variable section, the greater the increase in the ratio of uniform layer count intervals.

[0304] In one example, the diameter R of the electrode assembly is 22 mm, and the radius r of the core is... c With a radius of 2mm, from 9mm to 12mm, when the height of the cut section changes from 7mm to 10mm in the variable height range, the ratio of the uniform stacking number range can be reduced to about 30%.

[0305] In another example, the diameter R of the electrode assembly is 22 mm, and the radius r of the core is... c With a radius of 2mm, from 5mm to 6mm, when the height of the cut section changes from 3mm to 4mm in the variable height range, the ratio of the uniform stacking range increases to about 85%.

[0306] Therefore, the ratio of the radial length of the uniform stacking interval to the radial length of the winding including the slice is 30% or more, preferably 30% to 85%.

[0307] On the other hand, as referenced Figure 9a and Figure 9bAs explained, when the maximum height of the cut piece in the uniform height range is 6 mm to 10 mm, by changing the maximum height of the cut piece and the amount of cut piece increase in the radial direction, the number of layers of the uncoated portion 43a in the uniform layer number range can be adjusted to a range of 10 to 39. The uniform layer number range of the bent surface region F includes the region formed by bending the cut piece in the uniform height range. The thickness of the bent surface region F varies depending on the thickness of the material constituting the uncoated portion 43a. When the uncoated portion 43a is made of aluminum and its thickness is 10 μm to 25 μm, the uncoated portion layer thickness of the bent surface region F is 100 μm (0.1 mm) to 975 μm (0.975 mm). In this case, in the portion including the bent surface region F formed by bending a section with a height of 6 mm to 10 mm within a uniform height range, the ratio of the uncoated portion thickness of the bent surface region F to the height of the section is 1.0% (0.1 mm / 10 mm) to 16.3% (0.975 mm / 6 mm). In another example, when the uncoated portion 43a is made of copper and its thickness is 5 μm to 20 μm, the uncoated portion thickness of the bent surface region F is 50 μm (0.05 mm) to 780 μm (0.780 mm). In this case, in the portion including the bent surface region F formed by bending a section with a height of 6 mm to 10 mm within a uniform height range, the ratio of the uncoated portion thickness of the bent surface region F to the height of the section is 0.5% (0.05 mm / 10 mm) to 13.0% (0.780 mm / 6 mm). When the ratio of the thickness of the bent surface region F to the height of the segment included in the height uniform range meets the above-mentioned numerical range, the preferred welding strength is achieved when the current collector is welded to the bent surface region F.

[0308] The various electrode assembly structures of the embodiments (modifications) of the present invention are applicable to gel roll type cylindrical batteries or any battery known in the art.

[0309] Preferably, the cylindrical battery has a shape factor ratio (defined as the ratio of the diameter of the cylindrical battery to its height, i.e., the ratio of diameter Φ to height H) that is approximately greater than 0.4.

[0310] Here, the shape factor refers to the value representing the diameter and height of the cylindrical battery. For example, the shape factor of the cylindrical battery in one embodiment of the present invention is 46110, 4875, 48110, 4880, 4680, etc. In the shape factor values, the first two digits represent the diameter of the battery, and the remaining digits represent the height of the battery.

[0311] When using electrode assemblies with tabless structures in cylindrical batteries with a shape factor ratio exceeding 0.4, the stress applied radially to the uncoated portion is relatively large when bending it, making the uncoated portion prone to tearing. Furthermore, to ensure sufficient weld strength and reduce resistance when welding current collectors to the bent surface region of the uncoated portion, it is necessary to significantly increase the number of layers in the uncoated portion. These requirements can be met by the electrode plate and electrode assembly according to embodiments (modified examples) of the present invention.

[0312] According to one embodiment of the present invention, the battery is generally cylindrical in shape, and may be a cylindrical battery with a diameter of about 46 mm, a height of about 110 mm, and a shape factor ratio of 0.418.

[0313] According to another embodiment, the battery is generally cylindrical in shape, and may be a cylindrical battery with a diameter of about 48 mm, a height of about 75 mm, and a shape factor ratio of 0.640.

[0314] According to another embodiment, the battery is generally cylindrical in shape, and may be a cylindrical battery with a diameter of about 48 mm, a height of about 110 mm, and a shape factor ratio of 0.436.

[0315] According to another embodiment, the battery is generally cylindrical in shape, and may be a cylindrical battery with a diameter of about 48 mm, a height of about 80 mm, and a shape factor ratio of 0.600.

[0316] According to another embodiment, the battery is generally cylindrical in shape, and may be a cylindrical battery with a diameter of about 46 mm, a height of about 80 mm, and a shape factor ratio of 0.575.

[0317] Previously, batteries with a form factor ratio of approximately 0.4 or less were used. That is, batteries such as 1865 and 2170 were previously used. An 1865 battery has a diameter of approximately 18 mm and a height of approximately 65 mm, with a form factor ratio of 0.277. A 2170 battery has a diameter of approximately 21 mm and a height of approximately 70 mm, with a form factor ratio of 0.300.

[0318] The cylindrical battery according to an embodiment of the present invention will now be described in detail.

[0319] Figure 10 This is a cross-sectional view of a cylindrical battery 190 cut along the Y-axis according to an embodiment of the present invention.

[0320] Reference Figure 10According to an embodiment of the present invention, a cylindrical battery 190 includes an electrode assembly 110 comprising a first electrode, a separation membrane and a second electrode, a battery housing 142 for housing the electrode assembly 110 and a sealing member 143 for sealing the open end of the battery housing 142.

[0321] The battery casing 142 is a cylindrical container with an opening at the top. The battery casing 142 is made of a conductive metal such as aluminum or steel. The battery casing 142 houses the electrode assembly 110 and the electrolyte in its inner space through the opening at the top.

[0322] Electrolytes can be those with A + B - Salts with similar structures. Among them, A... + Including Li + Na + K + Ions consisting of basic metal cations or combinations thereof. Additionally, B... - Including the choice of F - Cl - ,Br - I - NO3 - N(CN)2 - BF4 - ClO4 - AlO4 - AlCl4 - PF6 - SbF6 - AsF6 - BF2C2O4 - BC4O8 - (CF3)2PF4 - (CF3)3PF3 - (CF3)4PF2 - (CF3) 5PF - (CF3) 6P - CF3SO3 - C4F9SO3, CF3CF2SO3 - (CF3SO2)2N - (FSO2)2N - CF3CF2(CF3)2CO - (CF3SO2)2CH - (SF5) 3C - (CF3SO2)3C - CF3(CF2)7SO3 - CF3CO2 -CH3CO2, SCN - and (CF3CF2SO2)2N - Any one or more anions that constitute a group.

[0323] Electrolytes can also be used in organic solvents. Suitable organic solvents include propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-pyrrolidone (NMP), ethyl methyl carbonate (EMC), γ-butyrolactone, or mixtures thereof.

[0324] The electrode assembly 110 can be any shape as long as it has a gel roll shape or a shape known in the art. For example... Figure 2 As shown, an electrode assembly 110 can be manufactured by winding a stack of a lower separation membrane, a first electrode, an upper separation membrane, and a second electrode at least once, with the winding center C as the reference.

[0325] The first and second electrodes have different polarities. That is, if one is anodic, the other is cathodic. At least one of the first and second electrodes may have an electrode structure according to the above-described embodiments (variables). Furthermore, the other of the first and second electrodes may have a conventional electrode structure or an electrode structure according to the embodiments (variables).

[0326] The electrode assembly 110 has an uncoated portion 146a of the first electrode and an uncoated portion 146b of the second electrode protruding from its upper and lower parts, respectively.

[0327] The seal 143 may include a plate-shaped cover 143a, a first gasket 143b that provides airtightness and insulation between the cover 143a and the battery housing 142, and a connecting plate 143c that is electrically and mechanically connected to the cover 143a.

[0328] The cover 143a is a component made of conductive metal and covers the upper opening of the battery casing 142. The cover 143a is electrically connected to the uncoated portion 146a of the first electrode and electrically insulated from the battery casing 142 by the first pad 143b. Therefore, the cover 143a can function as the first electrode terminal of the cylindrical battery 140.

[0329] The cover 143a is placed on the rolled edge 147 formed on the battery housing 142 and is fixed by the clamping part 148. A first pad 143b can be clamped between the cover 143a and the clamping part 148 to ensure the airtightness of the battery housing 142 and to achieve electrical insulation between the battery housing 142 and the cover 143a. The cover 143a may have a protrusion 143d that protrudes upward from its center.

[0330] The battery casing 142 is electrically connected to the uncoated portion 146b of the second electrode. Therefore, the battery casing 142 has the same polarity as the second electrode. If the second electrode is cathode, then the battery casing 142 is also cathode.

[0331] The battery housing 142 has a rolled edge portion 147 and a clamping portion 148 at its upper end. The rolled edge portion 147 is formed by pressing the outer circumference of the battery housing 142 inward. The rolled edge portion 147 prevents the electrode assembly 110 housed inside the battery housing 142 from leaking out through the upper opening of the battery housing 142, and also functions as a support portion for placing the sealing member 143.

[0332] A clamping portion 148 is formed on the upper part of the rolled edge portion 147. The clamping portion 148 has a shape that extends and bends in a manner that surrounds the outer peripheral surface of the cover 143a disposed on the rolled edge portion 147 and a portion of the upper surface of the cover 143a.

[0333] The cylindrical battery 140 may also include a first current collector 144 and / or a second current collector 145 and / or an insulator 146.

[0334] The first current collector 144 is plate-shaped and attached to the upper part of the electrode assembly 110. The first current collector 144 is made of a conductive metal such as aluminum, copper, or nickel, and is electrically connected to the bent surface area F1 formed by bending the uncoated portion 146a of the first electrode.

[0335] The first current collector 144 may be connected to a lead 149. The lead 149 may extend upwards towards the electrode assembly 110 and be attached to the connecting plate 143c, or may be directly attached to the lower surface of the cover 143a. The lead 149 may be attached to other components by soldering.

[0336] Preferably, the first current collector 144 can be integrally formed with the lead 149. In this case, the lead 149 can have a long plate-like shape extending outward from the center of the first current collector 144.

[0337] The bonding between the bent surface region F1 of the uncoated portion 146a and the first current collector 144 is achieved, for example, by laser welding. Laser welding can be performed by melting the wood portion of the current collector. Laser welding can also be replaced by resistance welding, ultrasonic welding, etc.

[0338] Preferably, the uncoated portion 146a is divided into multiple segments, and the bending surface region F1 is formed by bending the multiple segments toward the core C. In the bending surface region F1, the ratio of the radial length of the uncoated portion 146a with 10 or more layers to the radial length of the winding including the segments is 30% or more, more preferably 30% to 85%.

[0339] The welding area between the bent surface region F1 of the uncoated part 146a and the first current collector 144 overlaps with the uniform layer number interval W1 of the bent surface region F1 by at least 50%, and the higher the overlap ratio, the better.

[0340] When the bending surface region F1 of the uncoated portion 146a is formed by laser welding between the first current collector 144 and the uncoated portion 146a, the welding strength is preferably 2 kgf / cm². 2 More preferably 4 kgf / cm 2 The above. The upper limit of weld strength is determined by the specifications of the laser welding equipment. In one example, the weld strength is 8 kgf / cm². 2 Below, or 6 kgf / cm 2 The laser power used to indicate welding strength varies depending on the laser device. For example, the laser power ranges from 250W to 320W. As another example, the ratio of the laser power to the maximum power specification parameter of the laser welding device can be appropriately adjusted within a range of 40% to 100%.

[0341] When the welding strength meets the above-mentioned numerical range, even if there is a large vibration along the winding axis and / or radial direction towards the electrode assembly 110, the physical properties of the welding interface will not decrease, the volume of the weld bead is sufficient, and the resistance of the welding interface can be reduced.

[0342] A second current collector 145 having a plate shape is attached to the lower surface of the electrode assembly 110. One side of the second current collector 145 is attached to the bent surface area F2 formed by bending the uncoated portion 146b of the second electrode by welding, and the opposite side is attached to the inner bottom surface of the battery casing 142 by welding.

[0343] Preferably, the uncoated portion 146b is divided into multiple segments, and the bending surface region F2 is formed by bending the multiple segments toward the core C. In the bending surface region F2, the ratio of the radial length of the uncoated portion 146b with a stack number of 10 or more sheets to the radial length of the winding including the segments is 30% or more, more preferably 30% to 85%.

[0344] The bonding structure between the second current collector 145 and the uncoated portion 146b of the second electrode is substantially the same as the bonding structure between the first current collector 144 and the uncoated portion 146a of the first electrode.

[0345] The welding area between the bent surface area F2 of the uncoated part 146b and the second collector 145 overlaps with the uniform layer number interval W2 by at least 50%, and the higher the overlap ratio, the better.

[0346] When welding the bent surface region F2 of the uncoated portion 146b and the second current collector 145 using a laser, the weld strength is preferably 2 kgf / cm². 2 The above is preferred, with 4 kgf / cm² being more ideal. 2 The above applies. The upper limit of weld strength is determined based on the specifications of the laser welding equipment. In one example, the weld strength is 8 kgf / cm². 2 Below, or 6 kgf / cm 2 The laser power used to indicate welding strength varies depending on the laser device. For example, the laser power ranges from 250W to 320W. As another example, the ratio of the laser power to the maximum power specification parameter of the laser welding device can be appropriately adjusted within a range of 40% to 100%.

[0347] When the welding strength meets the above-mentioned numerical range, even if a large vibration is applied to the electrode assembly 110 according to the winding axis direction and / or radial direction, the physical properties of the welding interface will not decrease, the volume of the weld bead is sufficient, and the resistance of the welding interface can be reduced.

[0348] Insulator 146 may cover the first current collector 144. Insulator 146 covers the first current collector 144 above the first current collector 144, thereby preventing direct contact between the first current collector 144 and the inner surface of the battery casing 142.

[0349] The insulator 146 has a lead hole 151 to allow the lead 149 extending upward from the first current collector 144 to be pulled out. The lead 149 is pulled out upward through the lead hole 151 and attached to the lower surface of the connecting plate 143c or the lower surface of the cover 143a.

[0350] The perimeter of the insulator 146 is sandwiched between the first current collector 144 and the rolled edge 147, which can fix the combination of the electrode assembly 110 and the first current collector 144. As a result, the movement of the combination of the electrode assembly 110 and the first current collector 144 in the height direction of the battery 140 is restricted, thereby improving the assembly stability of the battery 140.

[0351] Insulator 146 may be made of an insulating polymer resin. In one example, insulator 146 may be made of polyethylene, polypropylene, polyimide, or polybutylene terephthalate.

[0352] The battery casing 142 may also include a vent 152 formed on its lower surface. The vent 152 corresponds to a region on the lower surface of the battery casing 142 that is thinner than the surrounding region. The vent 152 is structurally more fragile than the surrounding region. Therefore, if the cylindrical battery 190 malfunctions and the internal pressure increases to a certain level, the vent 152 will rupture, allowing the gas generated inside the battery casing 142 to escape to the outside.

[0353] The vent 152 can be formed continuously or discontinuously on the lower surface of the battery casing 142 in a circular pattern. In a modified example, the vent 152 can be formed as a straight line pattern or other patterns.

[0354] Figure 11 This is a cross-sectional view of a cylindrical battery 200 according to another embodiment of the present invention, cut along the Y-axis.

[0355] Reference Figure 11 ,and Figure 10 Compared to the cylindrical battery 190 shown, the structure of the electrode assembly of the cylindrical battery 200 is substantially the same, except that the remaining structure is different.

[0356] Specifically, the cylindrical battery 200 includes a battery housing 171 through which terminals 172 are provided. Terminals 172 are provided on the closed surface of the battery housing 171 (the upper surface of the drawing). Terminals 172 are riveted to the through hole of the battery housing 171 with an insulating second pad 173 placed in place. Terminals 172 protrude outwards in the direction of gravity and the opposite direction.

[0357] Terminal 172 includes a terminal protrusion 172a and a terminal insertion portion 172b. The terminal protrusion 172a protrudes outward from the closed surface of the battery housing 171. The terminal protrusion 172a may be located approximately at the center of the closed surface of the battery housing 171. The maximum diameter of the terminal protrusion 172a may be larger than the maximum diameter of the through hole formed in the battery housing 171. The terminal insertion portion 172b penetrates approximately at the center of the closed surface of the battery housing 171, thereby enabling electrical connection with the uncoated portion 146a of the first electrode. The lower edge of the terminal insertion portion 172b may be riveted to the inner surface of the battery housing 171. That is, the lower edge of the terminal insertion portion 172b may have a shape that curves towards the inner surface of the battery housing 171. The maximum diameter of the end of the terminal insertion portion 172b is larger than the maximum diameter of the through hole in the battery housing 171.

[0358] The lower cross-section of the terminal insertion portion 172b is substantially flat and is welded to the central portion of the first current collector 144, which is connected to the uncoated portion 146a of the first electrode. An insulator 174, made of insulating material, is located between the first current collector 144 and the inner surface of the battery casing 171. The insulator 174 covers the upper portion of the first current collector 144 and the upper edge portion of the electrode assembly 110. This prevents the uncoated portion 146a exposed on the outer periphery of the electrode assembly 110 from contacting the inner surface of the battery casing 171, which has a different polarity, and thus preventing a short circuit.

[0359] The insulator 174 contacts the inner side of the closing portion of the battery casing 171 and the top surface of the first current collector 144. For this purpose, the insulator 174 has a thickness corresponding to the separation distance between the inner side of the closing portion of the battery casing 171 and the top surface of the first current collector 144, or a thickness slightly thicker than the separation distance.

[0360] Preferably, the first current collector 144 is laser-welded to the bent surface region F1 of the uncoated portion 146a. At this time, the welding is performed in the bent surface region F1 of the uncoated portion 146a, which includes a region with a uniform number of layers of 10 or more of the uncoated portion 146a.

[0361] The ratio of the radial length of the uniform interval of the number of layers in the uncoated portion 146a, which has 10 or more layers, to the radial length of the winding coil including the cut piece, is 30% or more, more preferably 30% to 85%.

[0362] The welding area between the bent surface area F1 of the uncoated part 146a and the first current collector 144 overlaps with the uniform layer number interval W1 by at least 50%, and the higher the overlap ratio, the better.

[0363] When welding the bent surface region F1 of the uncoated portion 146a and the first current collector 144 using a laser, the preferred welding strength is 2 kgf / cm². 2 The above is preferred, with 4 kgf / cm² being more ideal. 2 The above. The upper limit of weld strength is determined by the specifications of the laser welding equipment. In one example, the weld strength is 8 kgf / cm². 2 Below, or 6 kgf / cm 2 The laser power used to indicate welding strength varies depending on the laser device. For example, the laser power ranges from 250W to 320W. As another example, the laser power can be appropriately adjusted within a range of 40% to 100% relative to the maximum power specification of the laser welding device.

[0364] When the welding strength meets the above-mentioned numerical range, even if a large vibration is applied to the electrode assembly 110 along the winding axis and / or radial direction, the physical properties of the welding interface will not decrease, the volume of the weld bead is sufficient, and the resistance of the welding interface can be reduced.

[0365] The second pad 173 is located between the battery casing 171 and the terminal 172, thereby preventing the battery casing 171 and the terminal 172, which have different polarities, from making electrical contact with each other. Thus, the upper surface of the battery casing 171, which has a generally flat shape, can function as the second electrode terminal of the cylindrical battery 200.

[0366] The second pad 173 includes a pad protrusion 173a and a pad insertion portion 173b. The pad protrusion 173a is sandwiched between the terminal protrusion 172a of the terminal 172 and the battery housing 171. The pad insertion portion 173b is sandwiched between the terminal insertion portion 172b of the terminal 172 and the battery housing 171. The pad insertion portion 173b deforms together with the terminal insertion portion 172b during reveting, so that it can fit tightly against the inner surface of the battery housing 171. The second pad 173 may, for example, be made of an insulating polymer resin.

[0367] The exposed portion 173a of the second pad 173 may have a shape that extends to cover the outer peripheral surface of the exposed portion 172a of the terminal 172. When the second pad 173 covers the outer peripheral surface of the terminal 172, short circuits can be prevented during the process of attaching electrical connection components such as buses to the upper surface of the battery housing 171 and / or the terminal 172. Although not shown in the figures, the exposed portion 173a may have a shape that extends to cover not only the outer peripheral surface of the exposed portion 172a but also a portion of the upper surface.

[0368] When the second pad 173 is made of a polymer resin, it can be thermally bonded to the battery housing 171 and the terminal 172. This enhances the airtightness of the interface between the second pad 173 and the terminal 172, as well as the interface between the second pad 173 and the battery housing 171. Alternatively, when the exposed portion 173a of the second pad 173 extends to the upper surface of the exposed portion 172a of the terminal, the terminal 172 can be integrally bonded to the second pad 173 via insert injection molding.

[0369] On the upper surface of the battery housing 171, the remaining area 175, excluding the area occupied by the terminal 172 and the second pad 173, corresponds to a second electrode terminal having the opposite polarity to the terminal 172.

[0370] The second current collector 176 is attached to the lower part of the electrode assembly 110. The second current collector 176 is made of conductive metals such as aluminum, steel, copper, and nickel, and is electrically connected to the uncoated part 146b of the second electrode.

[0371] Preferably, the second current collector 176 is electrically connected to the battery housing 171. For this purpose, the second current collector 176 is fixed such that at least a portion of its edge is located between the inner side surface of the battery housing 171 and the first pad 178b.

[0372] In one example, at least a portion of the edge of the second current collector 176 can be fixed to the rolled edge 17 by welding while supported by the lower end face of the rolled edge 180 formed at the lower end of the battery housing 171. In a modified example, at least a portion of the edge of the second current collector 176 can be directly welded to the inner wall surface of the battery housing 171.

[0373] Preferably, the second current collector 176 and the bent surface region F2 of the uncoated portion 146b are joined by welding, for example by laser welding. In this case, the welding is performed in the bent surface region F2 of the uncoated portion 146b, including a region with a uniform number of layers of the uncoated portion 146b, where the number of layers is 10 or more.

[0374] The number of layers in the uncoated portion 146b is 10 or more, and the ratio of its radial length to the radial length of the winding including the cut piece is 30% or more, more preferably 30% to 85%.

[0375] The welding area between the bent surface area F2 of the uncoated part 146b and the second collector 176 overlaps with the uniform layer number interval W2 by at least 50%, and the higher the overlap ratio, the better.

[0376] When welding the bent surface region F2 of the uncoated portion 146b and the second current collector 176 using a laser, the preferred welding strength is 2 kgf / cm².2 The above is preferred, with 4 kgf / cm² being more ideal. 2 above.

[0377] When the welding strength meets the above-mentioned numerical range, even if a large vibration is applied to the electrode assembly 110 along the winding axis and / or radial direction, the physical properties of the welding interface will not decrease, the volume of the weld bead is sufficient, and the resistance of the welding interface can be reduced.

[0378] The seal 178 for sealing the lower open end of the battery housing 171 includes a cover 178a and a first gasket 178b. The first gasket 178b electrically separates the cover 178a from the battery housing 171. A clamping part 181 simultaneously secures the edge of the cover 178a and the first gasket 178b. The cover 178a is provided with a vent 179. The configuration of the vent 179 is substantially the same as that in the above-described embodiment (modified example).

[0379] Preferably, the cover 178a is made of a conductive metal. However, a first gasket 178b is sandwiched between the cover 178a and the battery housing 171, so the cover 178a does not have electrical polarity. The seal 178 mainly functions to seal the open end at the bottom of the battery housing 171 and to release gas when the internal pressure of the battery 200 increases above a threshold.

[0380] Preferably, the terminal 172, which is electrically connected to the uncoated portion 146a of the first electrode, is used as the first electrode terminal. Furthermore, the portion 175 of the upper surface of the battery casing 171, excluding the terminal 172, which is electrically connected to the second uncoated portion 146b of the second electrode via the second current collector 176, is used as a second electrode terminal with a polarity different from the first electrode terminal. In this way, with both electrode terminals located on the upper part of the cylindrical battery 200, electrical connection components such as busbars can be arranged only on one side of the cylindrical battery 200. This simplifies the battery pack structure and increases energy density. Furthermore, the portion 175 used as the second electrode terminal has a generally flat shape, ensuring a sufficient contact area suitable for joining electrical connection components such as busbars. Therefore, the cylindrical battery 200 can reduce the resistance at the contact points of the electrical connection components to an optimal level.

[0381] In this invention, even if the uncoated portions 146a and 146b are bent toward the core, the core C of the electrode assembly 110 will not be blocked and will remain open to the upper part.

[0382] That is, such as Figure 4As shown in the figure, the height of the uncoated portion of the first and second electrodes, especially the height of the uncoated portion A on the core side, is designed to be lower. The height of the segment 61 is arranged in a variable range adjacent to the uncoated portion A on the core side. The height of the segment 61 closest to the uncoated portion A on the core side is adjusted so that even if the uncoated portion around the core of the electrode assembly 110 is bent, the core C of the electrode assembly 110 can be prevented from being blocked.

[0383] When the core C is not blocked, there are no difficulties in the electrolyte injection process, which can improve the electrolyte injection efficiency. In addition, the welding process between the current collector 145 and the bottom of the battery casing 142 or between the current collector 144 and the terminal 172 is easily achieved by inserting a welding fixture into the core C.

[0384] When the uncoated portions 146a and 146b satisfy the slitting structure, when the width and / or height and / or spacing of the lower surface segments are adjusted in a manner that satisfies the numerical range of the above embodiment, the segments are overlapped into multiple layers when they are bent, so as to ensure sufficient welding strength of the segments, and no empty spaces (gaps) are formed on the bent surface areas F1 and F2.

[0385] On the other hand, the first current collector 144 and the second current collector 176 may have Figure 12 and Figure 13 This new structure is shown.

[0386] Figure 12 This is a top top view showing the structure of the first current collector 144 according to an embodiment of the present invention.

[0387] Reference Figure 12 The first current collector 144 may include a contour portion 144a, a first uncoated portion joining portion 144b, and a terminal joining portion 144c. The contour portion 144a is disposed on the upper part of the electrode assembly 110. The contour portion 144a may have a generally rim shape with an empty space S formed therein. The accompanying drawings of the present invention only show the case where the contour portion 144a has a generally circular rim shape, but the present invention is not limited to this. Unlike the shape shown in the drawings, the contour portion 144a may also have a generally quadrilateral rim shape, a hexagonal rim shape, an octagonal rim shape, or other rim shapes.

[0388] To ensure sufficient welding area for bonding with the flat portion formed on the bottom surface of terminal 172, the terminal bonding portion 144c may have a diameter that is the same as or larger than the diameter of the flat portion formed on the bottom surface of terminal 172.

[0389] The first uncoated portion 144b extends inward from the contour portion 144a and engages with the uncoated portion 146a. The terminal engagement portion 144c is separate from the first uncoated portion 144b and is located inside the contour portion 144a. The terminal engagement portion 144c can be engaged with the terminal 172 by welding. The terminal engagement portion 144c can be located, for example, approximately at the center of the inner space surrounded by the contour portion 144a. The terminal engagement portion 144c can be provided at a position corresponding to the hole formed in the core portion C of the electrode assembly 110. The terminal engagement portion 144c can be configured to cover the hole formed in the core portion C of the electrode assembly 110 to prevent the hole formed in the core portion C of the electrode assembly 110 from being exposed on the outside of the terminal engagement portion 144c. For this purpose, the terminal engagement portion 144c can have a larger diameter or width than the hole formed in the core portion C of the electrode assembly 110.

[0390] The first uncoated portion joint 144b and the terminal joint 144c are not directly connected, but are configured to be separate from each other, and can be indirectly connected through the contour portion 144a. Thus, the first current collector 144 has a structure in which the first uncoated portion joint 144b and the terminal joint 144c are not directly connected but connected through the contour portion 144a, thereby dispersing the impact applied to the joint between the first uncoated portion joint 144b and the first uncoated portion 146a and the joint between the terminal joint 144c and the terminal 172 in the event of impact and / or vibration of the cylindrical battery 200. Only the case where there are four first uncoated portion joints 144b is shown in the accompanying drawings, but the present invention is not limited to this. Considering the manufacturing difficulty based on shape complexity, resistance, and the inner space of the contour portion 144a considering electrolyte impregnation, the number of the first uncoated portion joints 144b can be determined to be various numbers.

[0391] The first current collector 144 may further include a bridging portion 144d extending inward from the profile portion 144a and connecting to the terminal connection portion 144c. The bridging portion 144d may be formed such that at least a portion thereof has a smaller cross-sectional area than both the first uncoated connection portion 144b and the profile portion 144a. For example, the bridging portion 144d may be formed such that at least a portion thereof has a smaller width and / or thickness than the first uncoated connection portion 144b. In this case, the resistance of the bridging portion 144d increases, thereby causing overcurrent heating and melting in a portion of the bridging portion 144d when current flows through it, thus irreversibly cutting off the overcurrent. Considering this overcurrent cutting-off function, the cross-sectional area of ​​the bridging portion 144d can be adjusted to an appropriate level.

[0392] The aforementioned bridging portion 144d may have a tapered portion 144e whose width gradually narrows from the inner side of the contour portion 144a toward the terminal joint portion 144c. With the tapered portion 144e provided, the rigidity of the component at the connection between the bridging portion 144d and the contour portion 144a can be improved. With the tapered portion 144e provided, during the manufacturing process of the cylindrical battery 200, for example, a conveying device and / or an operator can hold the tapered portion 144e, thereby enabling simple and safe transport of the first current collector 144 and / or the assembly of the first current collector 144 and the electrode assembly 110. That is, with the tapered portion 144e provided, product defects that may occur when handling portions such as the first uncoated portion joint 144b and the terminal joint portion 144c that are welded to other components can be prevented.

[0393] Multiple first uncoated portion joints 144b may be provided. These multiple first uncoated portion joints 144b may be arranged at equal intervals separated from each other along the extension direction of the contour portion 144a. The extension length of each of the multiple first uncoated portion joints 144b may be approximately the same. The first uncoated portion joints 144b may be joined to the bent surface region F1 of the uncoated portion 146a by welding. The weld pattern 144f formed between the first uncoated portion joints 144b and the bent surface region W1 may have a structure extending in the radial direction of the electrode assembly 110. The weld pattern 144f may be an arrangement of line patterns or dot patterns.

[0394] The terminal joint 144c can be configured to be surrounded by a plurality of the aforementioned first uncoated joints 144b. The terminal joint 144c can be joined to the terminal 172 by welding. The bridging portion 144d can be located between a pair of adjacent first uncoated joints 144b. In this case, the distance from the bridging portion 144d along the extension direction of the contour portion 144a to any one of the pair of first uncoated joints 144b can be approximately the same as the distance from the bridging portion 144d along the extension direction of the contour portion 144a to the remaining one of the pair of first uncoated joints 144b. The cross-sectional area of ​​each of the plurality of first uncoated joints 144b can be formed to be approximately the same. The width and thickness of each of the plurality of first uncoated joints 144b can be formed to be approximately the same.

[0395] Although not shown, multiple bridging portions 144d may be provided. Each of the multiple bridging portions 144d may be configured between a pair of adjacent first uncoated portion joints 144b. The multiple bridging portions 144d may be configured at approximately the same intervals along the extending direction of the profile portion 144a. The distance from each of the multiple bridging portions 144d to any one of the pairs of adjacent first uncoated portion joints 144b along the extending direction of the profile portion 144a may be approximately the same as the distance to the remaining first uncoated portion joint 144b.

[0396] As described above, when multiple first uncoated portion joints 144b and / or bridging portions 144d are provided, if the distance between the multiple first uncoated portion joints 144b and / or the distance between the multiple bridging portions 144d and / or the distance between the first uncoated portion joints 144b and the bridging portions 144d is formed to a certain extent, the flow of current from the first uncoated portion joints 144b to the bridging portions 144d or from the bridging portions 144d to the first uncoated portion joints 144b can be smoothly and uniformly formed.

[0397] On the other hand, the bonding between the first current collector 144 and the bent surface region F1 of the uncoated portion 146a is achieved by welding. In this case, laser welding, ultrasonic welding, spot welding, etc., can be used, for example. Preferably, the welding area overlaps with the uniform layer number interval W1 of the bent surface region F1 by at least 50%.

[0398] The bridging portion 144d may include a recessed portion N formed by locally reducing the cross-sectional area of ​​the bridging portion 144d. The cross-sectional area of ​​the recessed portion N can be adjusted, for example, by locally reducing the width and / or thickness of the bridging portion 144d. With the recessed portion N provided, the resistance in the region where the recessed portion N is formed increases, thereby allowing for rapid current interruption in the event of an overcurrent.

[0399] To prevent impurities generated during breakage from flowing into the electrode assembly 110, it is preferable that the grooved portion N is provided in a region of the electrode assembly 110 corresponding to the uniform layer number range. This is because in this region, the layer number of the multiple segments of the uncoated portion 146a remains at its highest, thereby allowing the overlapping segments to function as a mask. For example, the grooved portion N can be provided in the region where the layer number of the uncoated portion 146a is the largest in the uniform layer number range.

[0400] Figure 13 This is a top top view showing the structure of the second current collector 176 according to an embodiment of the present invention.

[0401] Reference Figure 13The second current collector 176 is disposed at the lower part of the electrode assembly 110. Furthermore, the second current collector 176 can be configured to electrically connect the uncoated portion 146b of the electrode assembly 110 and the battery housing 171. The second current collector 176 is made of a conductive metal material and is electrically connected to the uncoated portion 146b. The second current collector 176 is also electrically connected to the battery housing 171. The second current collector 176 can be fixed between the inner surface of the battery housing 171 and the first pad 178b. Specifically, the second current collector 176 can be positioned between the lower surface of the rolled edge portion 180 of the battery housing 171 and the first pad 178b. It should be noted that the present invention is not limited to this; alternatively, the second current collector 176 can also be welded to the inner wall surface of the battery housing 171 in the area where the rolled edge portion 180 is not formed.

[0402] The second current collector 176 may include a support portion 176a disposed at the lower part of the electrode assembly 110, a second uncoated portion joint portion 176b extending from the support portion 176a substantially along the radial direction of the electrode assembly 110 and coupled to the bent surface region F2 of the uncoated portion 146b, and a housing joint portion 176c extending from the support portion 176a substantially along the radial direction of the electrode assembly 110 and coupled to the inner surface of the battery housing 171. The second uncoated portion joint portion 176b and the housing joint portion 176c are indirectly connected through the support portion 176a and are not directly connected to each other. Therefore, when an external impact is applied to the cylindrical battery 200 of the present invention, the possibility of damage to the joint portion of the second current collector 176 with the electrode assembly 110 and the joint portion of the second current collector 176 with the battery housing 171 can be minimized. It should be noted that the second current collector 176 of the present invention is not limited to a structure in which the second uncoated portion joint 176b and the housing joint 176c are indirectly connected. For example, the second current collector 176 may also have a structure without a support portion 176a that indirectly connects the second uncoated portion joint 176b and the housing joint 176c, and / or a structure in which the uncoated portion 176b and the housing joint 176c are directly connected to each other.

[0403] The aforementioned support portion 176a and the second uncoated portion joint portion 176b are disposed at the lower part of the electrode assembly 110. The aforementioned second uncoated portion joint portion 176b is joined to the bent surface region F2 of the uncoated portion 146b. In addition to the aforementioned second uncoated portion joint portion 176b, the aforementioned support portion 176a may also be joined to the uncoated portion 146b. The aforementioned second uncoated portion joint portion 176b and the uncoated portion 146b are joined by laser welding. When the battery housing 171 has a rolled edge portion 180, the aforementioned support portion 176a and the second uncoated portion joint portion 176b are located above the rolled edge portion 180.

[0404] The aforementioned support portion 176a has a current collector hole 176d formed at a position corresponding to the hole formed in the core portion C of the electrode assembly 110. The core portion C of the electrode assembly 110 and the current collector hole 176d, which are interconnected, can function as a welding rod for welding between the terminal 172 and the terminal joint portion 144c of the first current collector 144, or as a channel for irradiating a laser beam. The aforementioned current collector hole 176d has a diameter that is approximately the same as or larger than the hole formed in the core portion C of the electrode assembly 110. When the aforementioned second uncoated portion joint portion 176b is provided with multiple openings, the multiple second uncoated portion joint portions 176b can have a shape that extends substantially radially from the support portion 176a of the second current collector 176 toward the sidewall of the battery casing 171. Each of the aforementioned multiple second uncoated portion joint portions 176b can be positioned separately from each other along the periphery of the support portion 176a.

[0405] Multiple housing joints 176c may be provided. In this case, the multiple housing joints 176c may have a shape that extends generally radially from the center of the second current collector 176 toward the sidewall of the battery housing 171. This allows for electrical connection between the second current collector 176 and the battery housing 171 at multiple locations. By achieving the connection at multiple locations, the connection area is maximized and the resistance is minimized. Each of the multiple housing joints 176c may be positioned separately from each other along the periphery of the support portion 176a. At least one housing joint 176c may be located between adjacent second uncoated portion joints 176b. The multiple housing joints 176c may be joined to, for example, a rolled edge portion 180 on the inner surface of the battery housing 171. In particular, the multiple housing joints 176c may be joined to the lower surface of the rolled edge portion 180 by welding. Welding may be performed using laser welding, ultrasonic welding, or spot welding. By welding the housing joint 176c to the rolled edge 180 in this way, the resistance of the cylindrical battery 200 can be limited to about 4 mΩ or less, preferably 0.5 mΩ or more and 4 mΩ or less, and more than 1 mΩ or less and 4 mΩ or less. Furthermore, the shape of the rolled edge 180 extending in a direction substantially parallel to the upper surface of the battery housing 171 (i.e., in a direction substantially perpendicular to the sidewall of the battery housing 171) and the housing joint 176c extending in the same direction (i.e., in both the radial and circumferential directions) allows the housing joint 176c to stably contact the rolled edge 180. Moreover, by ensuring stable contact between the housing joint 176c and the flat portion of the rolled edge 180, welding between the two components can be smoothly achieved, thereby increasing the bonding force between the two components and minimizing the increase in resistance at the joint.

[0406] The aforementioned housing joint 176c may include a contact portion 176e attached to the inner side of the battery housing 171 and a connecting portion 176f connecting the support portion 176a and the contact portion 176e.

[0407] The aforementioned contact portion 176e is bonded to the inner side surface of the battery housing 171. When the battery housing 171 has a rolled edge portion 180, as described above, the contact portion 176e can be bonded to the rolled edge portion 180. More specifically, the contact portion 176e can be electrically bonded to a flat portion formed on the lower surface of the rolled edge portion 180 of the battery housing 171, and can be sandwiched between the lower surface of the rolled edge portion 180 and the first pad 178b. In this case, to achieve stable contact and bonding, the contact portion 176e can have a shape extending a predetermined length from the rolled edge portion 180 along the circumferential direction of the battery housing 171.

[0408] On the other hand, preferably, the maximum distance from the center of the second current collector 176 to the end of the second uncoated portion joint 176b along the radial direction of the electrode assembly 110 is formed to be the same as or smaller than the inner diameter of the battery housing 171 in the region where the rolled edge 180 is formed, i.e., the minimum inner diameter of the battery housing 171. This is so that when the shaping process of compressing the battery housing 171 along the height direction is performed, a gap is generated between the second current collectors 176 by the rolled edge 180, thereby preventing the second uncoated portion joint 176b from pressing against the edge of the electrode assembly 110.

[0409] The second uncoated portion joint 176b includes a hole 176g. The hole 176g can be used as a channel for electrolyte movement. The weld pattern 176h formed by welding the second uncoated portion joint 176b to the bent surface region W2 can have a structure extending in the radial direction of the electrode assembly 110. The weld pattern 176h can be an arrangement of line patterns or dot patterns.

[0410] The cylindrical battery 200 according to an embodiment of the present invention has the advantage of being able to make electrical connections at the top.

[0411] Figure 14 This is a top top view showing the electrical connection of multiple cylindrical batteries 200. Figure 15 yes Figure 14 A magnified view of a portion of the image.

[0412] Reference Figure 14 as well as Figure 15 Multiple cylindrical batteries 200 can be connected in series and in parallel at the top of the cylindrical batteries 200 via a bus 210. The number of cylindrical batteries 200 can be increased depending on the capacity of the battery pack.

[0413] In each cylindrical battery 200, terminal 172 is anode, and the flat surface 171a around terminal 172 of battery casing 171 can be cathode. Of course, the opposite is also possible.

[0414] Preferably, the multiple cylindrical batteries 200 can be configured as multiple columns and rows. Columns are shown vertically in the figure, and rows are shown horizontally in the figure. Furthermore, to maximize space efficiency, the multiple cylindrical batteries 200 can be configured as a closest packing structure. The closest packing structure is formed when the centers of the terminals 172 exposed to the outside of the battery housing 171 are connected to each other, forming an equilateral triangle shape. Preferably, the bus 210 connects the multiple cylindrical batteries 200 arranged in the same column side by side, and connects the multiple cylindrical batteries 200 arranged in two adjacent columns in series.

[0415] Preferably, for series and parallel connections, the bus 210 may include a main body 211, a plurality of first bus terminals 212, and a plurality of second bus terminals 213. The main body 211 may extend along the columns of the plurality of cylindrical batteries 200 between adjacent terminals 172. Alternatively, the main body 211 may extend along the columns of the plurality of cylindrical batteries 200 and bend regularly in a zigzag pattern.

[0416] Multiple first bus terminals 212 can extend to one side of the main body 211 and be electrically connected to terminals 172 of the cylindrical battery 200 located in the extending direction. The electrical connection between the first bus terminals 212 and terminals 172 can be achieved by laser welding, ultrasonic welding, or the like.

[0417] Multiple second bus terminals 213 can extend to the other side of the main body 211 and be electrically coupled to a flat surface 171a surrounding a terminal 172 located in the extending direction. The electrical coupling between the second bus terminals 213 and the flat surface 171a can be achieved by laser welding, ultrasonic welding, or the like.

[0418] Preferably, the main body 211, the plurality of first bus terminals 212, and the plurality of second bus terminals 213 can be constructed from a single conductive metal plate. The metal plate can be, for example, an aluminum plate or a copper plate, but the invention is not limited thereto. In a variation, the main body 211, the plurality of first bus terminals 212, and the second bus terminals 213 can be manufactured as separate blocks and then joined together by welding or the like.

[0419] The cylindrical battery 200 of the present invention described above has a structure in which resistance is minimized by increasing the welding area based on the bending surface regions F1 and F2, multiplexing the current path of the second current collector 176, and minimizing the length of the current path. The AC resistance of the cylindrical battery 200, measured by a resistance meter between the anode and cathode (i.e., between the terminal 172 and its surrounding flat surface 171a), can be approximately 4 mΩ or less suitable for fast charging, or 0.5 mΩ or more and 4 mΩ or less, preferably 1 mΩ or more and 4 mΩ or less.

[0420] According to the cylindrical battery 200 of the present invention, the terminal 172 having an anode and the flat surface 171a having a cathode are located in the same direction, so the electrical connection of multiple cylindrical batteries 200 can be easily realized by using the bus 210.

[0421] Furthermore, the cylindrical battery 200 has a large area of ​​terminal 172 and its surrounding flat surface 171a, thus ensuring sufficient bonding area of ​​bus 210 and significantly reducing the resistance of the battery pack including the cylindrical battery 200.

[0422] The cylindrical battery according to the above embodiments (modifications) can be used to manufacture battery packs.

[0423] Figure 16 This is a diagram that briefly illustrates the configuration of a battery pack according to an embodiment of the present invention.

[0424] Reference Figure 16 According to an embodiment of the present invention, the battery pack 300 includes an assembly of cylindrical batteries 301 electrically connected to each other and a housing 302 for housing the assembly. The cylindrical batteries 301 can be any one of the batteries according to the above-described embodiments (variations). In the accompanying drawings, for ease of illustration, components such as buses, cooling units, and external terminals for electrically connecting the multiple cylindrical batteries 301 are omitted.

[0425] The battery pack 300 can be installed in a vehicle. For example, the vehicle can be an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. Vehicles can be four-wheeled or two-wheeled.

[0426] Figure 17 It is used to illustrate including Figure 16 A picture of a car with a 300 battery pack.

[0427] Reference Figure 17 A vehicle V according to one embodiment of the present invention includes a battery pack 300 according to one embodiment of the present invention. The vehicle V receives power from the battery pack 300 according to one embodiment of the present invention for operation.

[0428] According to one aspect of the invention, when bending the uncoated portions exposed at both ends of the electrode assembly, it is ensured that the uncoated portions overlap by more than 10 sheets in the radial direction of the electrode assembly, thereby preventing damage to the separation membrane or active material layer during the welding of the current collector.

[0429] According to another aspect of the invention, the structure of the uncoated portion adjacent to the core of the electrode assembly is improved to prevent the cavity in the core of the electrode assembly from being blocked when the uncoated portion is bent, thereby enabling easy electrolyte injection and welding of the battery casing and current collector.

[0430] According to another aspect of the invention, instead of strip-shaped electrode tabs, the bent surface area of ​​the uncoated portion is directly welded to the current collector, thereby increasing energy density and providing an electrode assembly with reduced resistance.

[0431] According to another aspect of the invention, a cylindrical battery, including its battery pack, and an automobile can be provided with low internal resistance and improved weld strength between the current collector and the uncoated portion.

[0432] As described above, although the present invention has been illustrated with limited embodiments and drawings, the present invention is not limited thereto. Those skilled in the art to which this invention pertains should be able to make various modifications and variations within the technical concept and scope equivalent to the claims.

Claims

1. An electrode assembly defining a core and an outer peripheral surface by means of a first electrode, a second electrode, and a separation membrane intermediately therebetween, wound around an axis, characterized in that... The first electrode described above includes an uncoated portion at its long side end that protrudes to the outside of the separation membrane along the winding axis direction of the electrode assembly. in, A portion of the uncoated portion is bent in the radial direction of the electrode assembly to form a bent surface region including an overlapping layer of the uncoated portion. In a portion of the bent surface region, the number of layers of the uncoated portion in the winding axis direction of the electrode assembly is 10 or more. The current collector is welded to the bent surface area. Wherein, at least a portion of the welding area of ​​the current collector overlaps with a portion of the bending surface area, and Wherein, a portion of the bent surface region is spaced apart from the core of the electrode assembly in the radial direction.

2. The electrode assembly according to claim 1, characterized in that, Define the total number of winding turns of the first electrode as n1, and define the value obtained by dividing the winding turn index k at the k-th winding turn position by the total number of winding turns n1 as the relative radius position R relative to the winding turn index k. 1，k At that time, the R value that satisfies the condition that the number of layers of the uncoated part is 10 or more is within the relative radius position range of the uncoated part being bent. 1，k The length ratio of the radius direction interval is at least 30%, where k is a natural number from 1 to n1.

3. The electrode assembly according to claim 2, characterized in that, R, relative to the radius range of the uncoated portion being bent, satisfies the condition that the number of layers of the uncoated portion is 10 or more. 1，k The ratio of the radial direction interval length is 30% to 85%.

4. The electrode assembly according to claim 1, characterized in that, The second electrode described above includes an uncoated portion at its long side end that protrudes to the outside of the separation membrane along the winding axis direction of the electrode assembly. A portion of the uncoated portion is bent in the radial direction of the electrode assembly to form a bent surface region including an overlapping layer of the uncoated portion. In a portion of the bent surface region, the number of layers of the uncoated portion is 10 or more in the winding axis direction of the electrode assembly.

5. The electrode assembly according to claim 4, characterized in that, Define the total number of winding turns of the second electrode as n2, and define the value obtained by dividing the winding turn index k at the k-th winding turn position by the total number of winding turns n2 as the relative radius position R relative to the winding turn index k. 2，k At that time, relative to the relative radius position range where the uncoated portion is bent, R satisfies the condition that the number of layers of the uncoated portion is 10 or more. 2，k The length ratio of the radial direction interval is at least 30%, where k is a natural number from 1 to n².

6. The electrode assembly according to claim 5, characterized in that, The R value that satisfies the condition that the number of layers of the uncoated portion is 10 or more relative to the relative radius position range of the bent uncoated portion mentioned above. 2，k The length ratio of the radial direction interval is 30% to 85%.

7. The electrode assembly according to claim 2, characterized in that, In the winding structure of the first electrode described above, from the relative radius position R of the first winding loop 1，1 To the preset first relative radius position R of the k*th winding turn 1，k* The height of the uncoated portion of the preceding section is lower than the relative radius position R of the number of winding turns k*+1. 1，k*+1 The height of the uncoated portion within the interval of relative radius position 1.

8. The electrode assembly according to claim 2, characterized in that, In the winding structure of the first electrode described above, from the relative radius position R of the first winding loop 1，1 To the preset first relative radius position R of the k*th winding turn 1，k* The height of the uncoated portion of the preceding section is lower than the height of the aforementioned bent surface area formed by the overlap of the uncoated portions of the bend.

9. The electrode assembly according to claim 2, characterized in that, In the winding structure of the first electrode described above, from the relative radius position R of the first winding loop 1，1 To the first relative radius position R of the k*th winding turn 1，k* The section up to this point does not bend towards the core of the electrode assembly.

10. The electrode assembly according to claim 5, characterized in that, In the winding structure of the second electrode, from the relative radius position R of the first winding loop 2，1 To the preset first relative radius position R of the k*th winding turn 2，k* The height of the uncoated portion of the preceding interval is lower than the relative radius position R of the (k*+1)th winding turn. 2，k*+1 The height of the uncoated portion within the interval of relative radius position 1.

11. The electrode assembly according to claim 5, characterized in that, From the relative radius position R of the first winding loop 2，1 To the preset first relative radius position R of the k*th winding turn 2，k* The height of the uncoated portion of the preceding section is lower than the height of the bent surface area formed by the overlap of the uncoated portions of the bend.

12. The electrode assembly according to claim 5, characterized in that, From the relative radius position R of the first winding loop 2，1 To the preset first relative radius position R of the k*th winding turn 2，k* The uncoated portion of the section up to this point does not bend toward the core of the electrode assembly.

13. The electrode assembly according to claim 1 or 4, characterized in that, The uncoated portion of the first or second electrode is divided into multiple segments that can be bent independently of each other.

14. The electrode assembly according to claim 13, characterized in that, Each of the multiple segments has a geometric shape with a bend line as its base. The above geometric figures are formed by connecting one or more straight lines, one or more curves, or combinations thereof.

15. The electrode assembly according to claim 14, characterized in that, As the geometric figure moves from the bottom to the top, its width decreases in stages or continuously.

16. The electrode assembly according to claim 15, characterized in that, The lower interior angle between the base of the above geometric figure and the side that intersects the base is between 60 and 85 degrees.

17. The electrode assembly according to claim 16, characterized in that, The lower inner angles of the aforementioned plurality of segments increase in stages or gradually along a direction parallel to the winding direction of the aforementioned electrode assembly.

18. The electrode assembly according to claim 14, characterized in that, Each of the multiple segments has the shape of a trapezoid with a bend line as its base. Let r be the radius of the winding coil in which the slice is positioned with reference to the core center of the aforementioned electrode assembly, and let L be the arc length of the winding coil corresponding to the lower part of the slice. arc The lower interior angle is set as θ when the application of the slice is assumed to be parallel to the sides of a pair of slices adjacent to a winding loop of radius r. assumption At that time, the actual lower interior angle θ of the pair of adjacent segments is... real Satisfy the following mathematical expression: i real >θ assumption i assumption =90°-360°*(L arc / 2πr)*0.

5.

19. The electrode assembly according to claim 18, characterized in that, Taking the core center of the aforementioned electrode assembly as a reference, the arc length L of the winding loop corresponding to the lower part of the aforementioned section is... arc The corresponding inscribed angle is less than 45 degrees.

20. The electrode assembly according to claim 18, characterized in that, Taking the core center of the aforementioned electrode assembly as a reference, the overlap rate of adjacent segments arranged in a winding loop of radius r is defined by the mathematical formula (θ). real / θ assumptoin When -1), the overlap rate of the cut is greater than 0 and less than 0.

05.

21. The electrode assembly according to claim 14, characterized in that, When drawing a hypothetical circle through a pair of adjacent segments arranged in a winding loop of radius r, with the core center of the aforementioned electrode assembly as a reference, the pair of arcs through each segment overlap each other.

22. The electrode assembly according to claim 21, characterized in that, When the overlap rate of a segment is defined as the ratio of the length of the overlapping arc to the length of the arc passing through each segment, the overlap rate of the segment is greater than 0 and less than 0.

05.

23. The electrode assembly according to claim 2, characterized in that, In the winding structure of the first electrode described above, from the relative radius position R of the first winding loop 1，1 To the first relative radius position R of the k*th winding turn 1，k* The uncoated portion of the section up to this point has a height lower than the relative radius position R. 1，k*+1 The height of the uncoated portion within the range of relative radius position 1, without bending towards the core.

24. The electrode assembly according to claim 23, characterized in that, relative radius position R 1，1 To R 1，k* The length of the aforementioned first electrode relative to the relative radius position R 1，k*+1 The ratio of the length of the first electrode to that of 1 is 1% to 30%.

25. The electrode assembly according to claim 2, characterized in that, In the winding structure of the first electrode described above, the relative radius position R of the (k*+1)th winding loop is... 1，k*+1 Uncoated part bending length fd 1，k*+1 The relative radius position R of the first winding loop 1，1 To the k*th relative radius position R 1，k* Its radial length is short.

26. The electrode assembly according to claim 2, characterized in that, In the winding structure of the first electrode described above, the core radius of the electrode assembly is defined as r. c From the center of the core to 0.90r c The interval was not located at the relative radius position R of the (k*+1)th winding loop. 1，k*+1 The bends in the uncoated section of the interval up to 1 are covered.

27. The electrode assembly according to claim 26, characterized in that, The relative radius position R of the (k*+1)th winding loop 1，k*+1 Uncoated part bending length fd 1，k*+1 The radius r of the core c and relative radius position R 1，k*+1 The distance d separated from the center of the electrode assembly 1，k*+1 Satisfy the following mathematical expression: fd 1，k*+1 +0.90*r c ≤d 1，k*+1 。 28. The electrode assembly according to claim 5, characterized in that, In the winding structure of the second electrode described above, the relative radius position R of the first winding loop... 2，1 To the first relative radius position R of the k*th winding turn 2，k* The uncoated portion of the interval, whose height is lower than the relative radius position R of the k*+1th winding turn. 2，k*+1 The height of the uncoated portion within the range of relative radius position 1, without bending towards the core.

29. The electrode assembly according to claim 28, characterized in that, relative radius position R 2，1 To R 2，k* The length of the aforementioned second electrode relative to the relative radius position R 2，k*+1 The ratio of the length of the second electrode to that of 1 is 1% to 30%.

30. The electrode assembly according to claim 5, characterized in that, In the winding structure of the second electrode described above, the relative radius position R located at the (k*+1)th winding loop is... 2，k*+1 The bending length fd of the uncoated part 2，k*+1 The relative radius position R of the first winding loop 2，1 To the first relative radius position R of the k*th winding turn 2，k* Its radial length is short.

31. The electrode assembly according to claim 5, characterized in that, In the winding structure of the second electrode described above, the core radius of the electrode assembly is defined as r. c At that time, from the center of the core to 0.90r c The interval is not located at the relative radius position R of the (k*+1)th winding loop. 2，k*+1 The bend in the uncoated portion of the second electrode within the range of relative radius 1 is shielded.

32. The electrode assembly according to claim 31, characterized in that, The relative radius position R of the (k*+1)th winding loop 2，k*+1 Uncoated part bending length fd 2，k*+1 The radius r of the core c and relative radius position R 2，k*+1 The distance d separated from the center of the electrode assembly 2，k*+1 Satisfy the following mathematical expression: fd 2，k*+1 +0.90*r c ≤d 2，k*+1 。 33. The electrode assembly according to claim 2, characterized in that, In the winding structure of the first electrode described above, the relative radius position R of the (k*+1)th winding loop is... 1，k*+1 To the preset second relative radius position R of the k@th winding turn 1，k@ The uncoated portion of the interval is cut into multiple segments, and its height gradually or in stages increases along a direction parallel to the winding direction.

34. The electrode assembly according to claim 33, characterized in that, Relative radius position R 1，k*+1 To R 1，k@ The ratio of the radial length of the interval to the radius of the winding structure of the first electrode excluding the core is 1% to 56%.

35. The electrode assembly according to claim 2, characterized in that, In the winding structure of the first electrode described above, from the preset relative radius position R of the k@+1th winding turn... 1，k@+1 The uncoated portion of the first electrode up to relative radius position 1 is divided into multiple segments, the height of which varies from relative radius position R. 1，k@+1 They are essentially the same up to the relative radius position 1.

36. The electrode assembly according to claim 5, characterized in that, In the winding structure of the second electrode described above, the relative radius position R of the (k*+1)th winding loop is... 2，k*+1 To the preset second relative radius position R of the k@th winding turn 2，k@ The uncoated portion of the section is divided into multiple segments, and its height increases in stages or gradually along a direction parallel to the winding direction.

37. The electrode assembly according to claim 36, characterized in that, Relative radius position R 2，k*+1 To R 2，k@ The ratio of the radial length of the interval to the radius of the winding structure of the second electrode excluding the core is 1% to 56%.

38. The electrode assembly according to claim 5, characterized in that, In the winding structure of the second electrode described above, from the second relative radius position R of the k@+1th winding turn 2，k@+1 The uncoated portion of the second electrode up to relative radius position 1 is divided into multiple segments, the height of which starts from the relative radius position R of the k@+1th winding turn. 2，k@+1 They are essentially the same up to the relative radius position 1.

39. The electrode assembly according to claim 1, characterized in that, In the winding structure of the first electrode described above, the uncoated portion bent in the radial direction of the electrode assembly is divided into multiple segments that can be bent independently. At least one of the height in the winding axis direction and the width in the winding direction of the multiple sections is increased individually or in groups along a direction parallel to the winding direction, either gradually or in stages.

40. The electrode assembly according to claim 4, characterized in that, In the winding structure of the second electrode described above, the uncoated portion bent in the radial direction of the electrode assembly is divided into multiple segments that can be bent independently. At least one of the height in the winding axis direction and the width in the winding direction of the multiple sections is increased individually or in groups along a direction parallel to the winding direction, either gradually or in stages.

41. The electrode assembly according to claim 13, characterized in that, The multiple cut pieces each satisfy at least one of the following conditions: a width condition of 1 mm to 11 mm in the winding direction; a height condition of 2 mm to 10 mm in the winding axis direction; and a separation distance condition of 0.05 mm to 1 mm in the winding direction.

42. The electrode assembly according to claim 13, characterized in that, The cut-off groove is located between the above-mentioned multiple cut pieces. A predetermined gap exists between the lower end of the cut-off groove and the active material layer of the first electrode or the second electrode.

43. The electrode assembly according to claim 42, characterized in that, The length of the aforementioned gap is 0.2 mm to 4 mm.

44. The electrode assembly according to claim 13, characterized in that, Multiple strips are formed into multiple strip groups along the winding direction of the electrode assembly. For strips belonging to the same strip group, at least one of the following is substantially the same: width in the winding direction, height in the winding axis direction, and separation distance in the winding direction.

45. The electrode assembly according to claim 44, characterized in that, For cut pieces belonging to the same cut piece group, as they approach a direction parallel to the winding direction of the aforementioned electrode assembly, at least one of the following—width in the winding direction, height in the winding axis direction, and separation spacing in the winding direction—gradually or in stages increases.

46. ​​The electrode assembly according to claim 44, characterized in that, At least a portion of the multiple cut pieces are configured on the same winding as the electrode assembly.

47. The electrode assembly according to claim 1, characterized in that, The bent surface region formed by the uncoated portion of the first electrode includes a layer number increasing range and a layer number uniform range from the outer periphery to the core of the electrode assembly. The aforementioned range of increasing layer count is defined as the range in which the layer count of the uncoated portion increases as it approaches the core of the electrode assembly. The aforementioned range of uniform layer count is defined as the range from the position where the increase in the layer count of the uncoated portion stops to the radius position where the uncoated portion begins to bend. The ratio of the radial length of the uniformly stacked interval to the radial length from the start of the bend in the uncoated portion to the end of the bend in the uncoated portion is 30% or more.

48. The electrode assembly according to claim 5, characterized in that, The bent surface region formed by the uncoated portion of the second electrode includes a region of increasing layer count and a region of uniform layer count from the outer periphery of the electrode assembly toward the core. The aforementioned range of increasing layer count is defined as the range in which the layer count of the uncoated portion increases as it approaches the electrode assembly. The aforementioned range of uniform layer count is defined as the range from the position where the increase in the layer count of the uncoated portion stops to the radius position where the uncoated portion begins to bend. The ratio of the radial length of the uniformly stacked interval to the radial length from the start of the bend in the uncoated portion to the end of the bend in the uncoated portion is 30% or more.

49. The electrode assembly according to claim 4, characterized in that, The thickness of the first electrode and the second electrode mentioned above is 80 μm to 250 μm. The spacing between the uncoated portions of adjacent winding loops in the radial direction of the aforementioned electrode assembly is 200 μm to 500 μm.

50. The electrode assembly according to claim 1, characterized in that, The thickness of the uncoated portion of the first electrode is 10 μm to 25 μm.

51. The electrode assembly according to claim 4, characterized in that, The thickness of the uncoated portion of the second electrode is 5 μm to 20 μm.

52. The electrode assembly according to claim 1, characterized in that, In a portion of the bent surface region formed by the uncoated portion of the first electrode, the total stack thickness of the overlapping layers of the uncoated portion is between 100 μm and 975 μm.

53. The electrode assembly according to claim 52, characterized in that, The uncoated portion of the first electrode is divided into multiple segments that can be independently divided. The first electrode includes a height-variable range of segments with variable height and a height-uniform range of segments with uniform height. In the bending surface region, the segments included in the height-uniform range are bent along the radial direction of the assembly to form a region. The ratio of the uncoated portion stack thickness of the bending surface region to the height of the segments is 1.0% to 16.3%.

54. The electrode assembly according to claim 4, characterized in that, In a portion of the bent surface region formed by the uncoated portion of the second electrode, the total stack thickness of the overlapping layers of the uncoated portion is 50 μm to 780 μm.

55. The electrode assembly according to claim 54, characterized in that, The uncoated portion of the second electrode is divided into multiple segments that can be independently divided. The second electrode includes a height-variable range of segments with variable height and a height-uniform range of segments with uniform height. In the bending surface region, the segments included in the height-uniform range are bent along the radial direction of the component to form a region. The ratio of the uncoated portion stack thickness of the bending surface region to the height of the segments is 0.5% to 13.0%.

56. An electrode assembly that defines a core and an outer peripheral surface by being wound around an axis via a first electrode, a second electrode, and a separation membrane between them. The electrode assembly is characterized by the following features: The first electrode described above includes a first uncoated portion at its long side end that protrudes to the outside of the separation membrane along the winding axis direction of the electrode assembly. A portion of the aforementioned first uncoated portion is bent in the radial direction of the aforementioned electrode assembly to form a first bent surface region. In a portion of the aforementioned first bent surface region, the stack thickness of the aforementioned first uncoated portion is 100 μm to 975 μm. in, The current collector is welded to the first bent surface area. Wherein, at least a portion of the welding area of ​​the current collector overlaps with a portion of the area of ​​the first bent surface region, and Wherein, a portion of the first bent surface region is spaced apart from the core of the electrode assembly in the radial direction.

57. The electrode assembly according to claim 56, characterized in that, The first uncoated portion of the first electrode is divided into multiple segments that can be independently divided. The first electrode includes a height-variable range of segments with variable height and a height-uniform range of segments with uniform height. In the bending surface region, the segments included in the height-uniform range are bent along the radial direction of the component to form a region. The ratio of the uncoated portion stack thickness of the bending surface region to the height of the segments is 1.0% to 16.3%.

58. The electrode assembly according to claim 56, characterized in that, The second electrode described above includes a second uncoated portion at its long side end that protrudes to the outside of the separation membrane along the winding axis direction of the electrode assembly. A portion of the aforementioned second uncoated portion is bent in the radial direction of the aforementioned electrode assembly to form a second bent surface region. In a portion of the second bent surface region, the thickness of the second uncoated portion is between 50 μm and 780 μm.

59. The electrode assembly according to claim 58, characterized in that, The second uncoated portion of the second electrode is divided into multiple segments that can be independently divided. The second electrode includes a height-variable range of segments with variable height and a height-uniform range of segments with uniform height. In the bending surface region, the segments included in the height-uniform range are bent along the radial direction of the component to form a region. The ratio of the uncoated portion stack thickness of the bending surface region to the height of the segments is 0.5% to 13.0%.

60. A battery, characterized in that, include: An electrode assembly is defined by winding around an axis with a first electrode, a second electrode, and a separation membrane between them to define a core and an outer peripheral surface. At least one of the first electrode and the second electrode includes an uncoated portion exposed to the outside of the separation membrane along the winding axis of the electrode assembly at its long side end. At least a portion of the uncoated portion is bent in the radial direction of the electrode assembly to form a bent surface region. The number of layers of the uncoated portion in a portion of the bent surface region is 10 or more. The battery casing houses the electrode assembly and is electrically connected to one of the first electrode and the second electrode, thus having a first polarity. A sealing body that seals the open end of the aforementioned battery casing; A terminal, electrically connected to the first electrode and another electrode of the second electrode, having a second polarity with its surface exposed to the outside; and A current collector, which is welded to the aforementioned bent surface area and electrically connected to either the aforementioned battery casing or the aforementioned terminals. The welding area of ​​the aforementioned current collector overlaps with the bent surface area of ​​the aforementioned uncoated portion where the number of layers is 10 or more. Wherein, a portion of the bent surface region is spaced apart from the core of the electrode assembly in the radial direction.

61. The battery according to claim 60, characterized in that, The first electrode described above includes a first uncoated portion at its long side end that protrudes to the outside of the separation membrane along the winding axis direction of the electrode assembly. The total number of winding turns of the first electrode is defined as n1. The value obtained by dividing the winding turn index k at the k-th winding turn position by the total number of winding turns n1 is defined as the relative radius position R relative to the winding turn index k. 1，k At that time, relative to the relative radius position range where the first uncoated portion is bent, R satisfies the condition that the number of layers of the first uncoated portion is 10 or more. 1，k The length ratio of the radius direction interval is at least 30%, where k is a natural number from 1 to n1.

62. The battery according to claim 60, characterized in that, The second electrode described above includes a second uncoated portion at its long side end that protrudes to the outside of the separation membrane along the winding axis direction of the electrode assembly. The total number of winding turns of the second electrode is defined as n2. The value obtained by dividing the winding turn index k at the k-th winding turn position by the total number of winding turns n2 is defined as the relative radius position R relative to the winding turn index k. 2，k At that time, relative to the relative radius position range where the second uncoated portion is bent, R satisfies the condition that the number of layers of the second uncoated portion is 10 or more. 2，k The length ratio of the radial direction interval is at least 30%, where k is a natural number from 1 to n².

63. The battery according to claim 60, characterized in that, The welding area of ​​the current collector overlaps by more than 50% with the bending surface area of ​​the uncoated part having a layer count of 10 or more.

64. The battery according to claim 63, characterized in that, The weld strength of the welded area of ​​the aforementioned current collector is 2 kgf / cm. 2 above.

65. A battery, characterized in that, It includes: An electrode assembly is defined by winding around an axis with a first electrode, a second electrode, and a separation membrane between them to define a core and an outer peripheral surface. The first electrode includes a first uncoated portion at its long side end that protrudes to the outside of the separation membrane along the winding axis of the electrode assembly. A portion of the first uncoated portion is bent in the radial direction of the electrode assembly to form a first bent surface region. The overlap thickness of the first uncoated portion in a portion of the first bent surface region is 100 μm to 975 μm. The battery casing houses the electrode assembly and is electrically connected to one of the first electrode and the second electrode, thus having a first polarity. A sealing body that seals the open end of the aforementioned battery casing; A terminal, electrically connected to the first electrode and another electrode of the second electrode, having a second polarity exposed to the outside; and The first current collector is soldered to the first bent surface area and electrically connected to either the battery casing or the terminal. The welding area of ​​the first current collector overlaps with a portion of the first bent surface area, which has a laminate thickness of 100µm to 975µm for the first uncoated portion. Wherein, a portion of the first bent surface region is spaced apart from the core of the electrode assembly in the radial direction.

66. The battery according to claim 65, characterized in that, The first uncoated portion of the first electrode is divided into multiple segments that can be independently divided. The first electrode includes a height-variable range of segments with variable height and a height-uniform range of segments with uniform height. In the first bending surface region, the segments included in the height-uniform range are bent along the radial direction of the component to form a region. The ratio of the uncoated portion stack thickness of the first bending surface region to the height of the segments is 1.0% to 16.3%.

67. The battery according to claim 65, characterized in that, The welding strength of the welding area of ​​the first current collector is 2 kgf / cm². 2 above.

68. The battery according to claim 65, characterized in that, The second electrode includes a second uncoated portion at its long side end that protrudes to the outside of the separation membrane along the winding axis of the electrode assembly. A portion of the second uncoated portion is bent in the radial direction of the electrode assembly to form a second bent surface region. The stacking thickness of the second uncoated portion in a portion of the second bent surface region is 50 μm to 780 μm. The battery includes a second current collector welded to the second bent surface area and electrically connected to either the battery casing or another of the terminals. The welding area of ​​the second current collector overlaps with a portion of the second bent surface area, which has a layer thickness of 50 μm to 780 μm.

69. The battery according to claim 68, characterized in that, The second uncoated portion of the second electrode is divided into multiple segments that can be independently divided. The second electrode includes a height-variable range of segments with variable height and a height-uniform range of segments with uniform height. In the second bending surface region, the segments included in the height-uniform range are bent along the radial direction of the component to form a region. The ratio of the uncoated portion stack thickness of the second bending surface region to the height of the segments is 0.5% to 13%.

70. The battery according to claim 68, characterized in that, The welding strength in the welding area of ​​the second current collector mentioned above is 2 kgf / cm. 2 above.

71. The battery according to claim 65, characterized in that, The welding area of ​​the first current collector overlaps by more than 50% with a portion of the first bent surface area of ​​the first uncoated portion, which has a layer thickness of 100µm to 975µm.

72. The battery according to claim 68, characterized in that, The welding area of ​​the second current collector overlaps by more than 50% with a portion of the second bent surface area of ​​the second uncoated portion, which has a layer thickness of 50 μm to 780 μm.

73. A battery pack, characterized in that, It includes the battery according to any one of claims 60 to 72.

74. A car, characterized in that, It includes the battery pack as described in claim 73.

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