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

Abstract

To provide an electrode assembly, a battery, and a battery pack and a vehicle including the same.SOLUTION: Disclosed are an electrode assembly, a battery, and a battery pack and a vehicle including the same. The electrode assembly includes a first electrode, a second electrode, and a separator interposed between the first and second electrodes, the first electrode and the second electrode being wound around an axis to define a core and an outer circumferential surface, wherein the first electrode includes a non-coating portion exposed to an outside of the separator along a winding axis direction of the electrode assembly at an end portion of a long side of the first electrode, a portion of the non-coating portion is bent in a radial direction of the electrode assembly to form a bent surface region, and in a portion of the bent surface region, the number of stacked non-coating portions is 10 or more in the winding axis direction of the electrode assembly.SELECTED DRAWING: Figure 9a

Description

[Technical Field]

[0001] The present invention relates to an electrode assembly, a battery, a battery pack including the same, and a vehicle.

[0002] This application is a Korean Patent Application No. 10-2021-0007278 filed on January 19, 2021, Korean Patent Application No. 10-2021-0022897 filed on February 19, 2021, Korean Patent Application No. 10-2021-0022894 filed on February 19, 2021, Korean Patent Application No. 10-2021-0022891 filed on February 19, 2021, Korean Patent Application No. 10-2021-0022881 filed on February 23, 2021, Korean Patent Application No. 10-2021-0024424 filed on March 31, 2021 Korean Patent Application No. 10-2021-0030300 filed on March 8, 2021, Korean Patent Application No. 10-2021-0030291 filed on March 8, 2021, Korean Patent Application No. 10-2021-0046798 filed on April 9, 2021, Korean Patent Application No. 10-2021-0058183 filed on May 4, 2021, Korean Patent Application No. 10-2021-0077046 filed on June 14, 2021, Korean Patent Application No. 10-2021-0084326 filed on June 28, 2021, Korean Patent Application No. 10-2021-0084326 filed on October 1, 2021 10-2021-0131225, Korean Patent Application No. 10-2021-0131215 filed on October 1, 2021, Korean Patent Application No. 10-2021-0131205 filed on October 1, 2021, Korean Patent Application No. 10-2021-0131208 filed on October 1, 2021, Korean Patent Application No. 10-2021-0131207 filed on October 14, 2021, Korean Patent Application No. 10-2021-0137001 filed on October 15, 2021 137856, Korean Patent Application No. 10-2021-0142196 filed on October 22, 2021, Korean Patent Application No. 10-2021-0153472 filed on November 9, 2021, Korean Patent Application No. 10-2021-0160823 filed on November 19, 2021, Korean Patent Application No. 10-2021-0163809 filed on November 24, 2021, Korean Patent Application No. 10-2021-0165866 filed on November 26, 2021, Korean Patent Application No. 10-2021-0172446 filed on December 3, 2021,Korean Patent Application No. 10-2021-0177091 filed on December 10, 2021, Korean Patent Application No. 10-2021-0194593 filed on December 31, 2021, Korean Patent Application No. 10-2021-0194610 filed on December 31, 2021, Korean Patent Application No. 10-2021-0194572 filed on December 31, 2021, Priority is claimed based on Korean Patent Application No. 10-2021-0194612 filed on December 31, 2021, Korean Patent Application No. 10-2021-0194611 filed on December 31, 2021, and Korean Patent Application No. 10-2022-0001802 filed on January 5, 2022, and the contents disclosed in the specifications and drawings of those applications are incorporated herein in their entirety. [Background technology]

[0003] Secondary batteries, which have high applicability to each product group and electrical properties such as high energy density, are widely used not only in portable devices but also in electric vehicles (EVs) and hybrid electric vehicles (HEVs) that are driven by electrical sources.

[0004] These secondary batteries not only have the primary advantage of dramatically reducing the use of fossil fuels, but are also environmentally friendly as they do not produce any by-products from energy use, and are attracting attention as a new energy source for improving energy efficiency.

[0005] Currently, secondary batteries such as lithium ion batteries, lithium polymer batteries, nickel cadmium batteries, nickel metal hydride batteries, and nickel zinc batteries are widely used. The operating voltage of such unit secondary batteries, i.e., unit batteries, is approximately 2.5V to 4.5V. Therefore, if a higher output voltage is required, a battery pack is constructed by connecting multiple batteries in series. Alternatively, a battery pack may be constructed by connecting multiple batteries in parallel depending on the required charge / discharge capacity of the battery pack. Therefore, the number of batteries included in the battery pack and the electrical connection configuration can be variously set depending on the required output voltage and / or charge / discharge capacity.

[0006] Meanwhile, known types of unit secondary batteries include cylindrical, prismatic, and pouch-type batteries. In cylindrical batteries, a separator, an insulator, is interposed between a positive electrode and a negative electrode, which is then wound up to form a jelly-roll-shaped electrode assembly. This assembly is then inserted into a battery housing to complete the battery. Strip-shaped electrode tabs are connected to the uncoated portions of the positive and negative electrodes, electrically connecting the electrode assembly to the exposed electrode terminals. For reference, the positive electrode terminal is a sealing cap that seals the opening of the battery housing, and the negative electrode terminal is the battery housing. However, conventional cylindrical batteries with this structure suffer from problems such as high resistance, excessive heat generation, and poor current collection efficiency due to current concentration at the strip-shaped electrode tabs connected to the positive and / or negative electrode uncoated portions.

[0007] Resistance and heat generation are not a major issue for small cylindrical batteries with form factors such as 1865 (diameter: 18mm, height: 65mm) and 2170 (diameter: 21mm, height: 70mm). However, when the form factor of cylindrical batteries is increased to be used in electric vehicles, a large amount of heat is generated around the electrode tabs during the fast charging process, which can cause the cylindrical battery to catch fire.

[0008] To solve this problem, a cylindrical battery (so-called tab-less cylindrical battery) has been proposed, which has a structure in which positive and negative electrode uncoated areas are located at the top and bottom of a jelly-roll type electrode assembly, respectively, and current collectors are welded to these uncoated areas to improve current collection efficiency.

[0009] Figures 1 to 3 show the manufacturing process of a tabless cylindrical battery. Figure 1 shows the structure of the electrode, Figure 2 shows the electrode winding process, and Figure 3 shows the process of welding a current collector to the folded surface area of ​​the uncoated portion.

[0010] 1 to 3, the positive electrode 10 and the negative electrode 11 have a structure in which an active material 21 is coated on a sheet-shaped current collector 20, and include a plain portion 22 on one long side along the winding direction X.

[0011] The electrode assembly A is fabricated by sequentially stacking a positive electrode 10 and a negative electrode 11 together with two separators 12 as shown in FIG. 2 and then winding the stack in one direction (X-axis direction). In this case, the uncoated portion of the positive electrode 10 and the uncoated portion of the negative electrode 11 are arranged in opposite directions. The positions of the positive electrode 10 and the negative electrode 11 may be reversed to those shown in the figure.

[0012] After the winding process, the uncoated portion 10a of the positive electrode 10 and the uncoated portion 11a of the negative electrode 11 are folded toward the core to form folded surface regions, and then the current collectors 30 and 31 are welded to the uncoated portions 10a and 11a, respectively.

[0013] No separate electrode tabs are attached to the positive electrode uncoated region 10a and the negative electrode uncoated region 11a, and 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 electrode assembly A (see arrow), which has the advantage of reducing battery resistance, since resistance is inversely proportional to the cross-sectional area of ​​the path through which current flows.

[0014] In a table-less cylindrical battery, in order to improve the welding characteristics between the plain portions 10a, 11a and the current collectors 30, 31, strong pressure must be applied to the welding points of the plain portions 10a, 11a to bend the plain portions 10a, 11a as flat as possible.

[0015] When uncoated portions 10a and 11b are folded, uncoated portion 32 adjacent to the core of electrode assembly A is folded, blocking all or a substantial portion of cavity 33 in the core of electrode assembly A. This causes problems during the electrolyte injection process. Cavity 33 in the core of electrode assembly A serves as a passage for injecting electrolyte. However, blocking this passage makes it difficult to inject electrolyte. Furthermore, when an electrolyte injector is inserted into cavity 33, it interferes with uncoated portion 32 that is folded near the core, potentially causing tearing of uncoated portion 32.

[0016] In addition, the bent portions of the plain portions 10a and 11a where the current collectors 30 and 31 are welded must be overlapped with no open spaces (gaps), which ensures sufficient welding strength and prevents the laser from penetrating into the electrode assembly A and melting the separator or active material when using cutting-edge technology such as laser welding.

[0017] In order for the plain portions 10a, 11a to overlap with the same number of layers, the plain portions 10a, 11a at the corresponding positions must be folded toward the core based on the position of each winding turn, with the inner winding turn covering the top surface of the folded plain portion. Furthermore, if the spacing between the winding turns is d and the folding length of the plain portions 10a, 11a of each winding turn is e, the folding length e must be at least d × n (n is a natural number greater than or equal to 2). Otherwise, an area where the same number of plain portions 10a, 11a overlaps multiple times will not be created. Furthermore, to ensure that the same number of overlapping areas of the plain portions 10a, 11a are sufficiently formed in the radial direction of the electrode assembly, the lengths of the plain portions 10a, 11a must be sufficiently long. However, because the radius of the electrode assemblies included in small cylindrical batteries is small, there is no motivation to conceive of the concept of designing the folding length of the plain portions 10a, 11a to be sufficiently long. Summary of the Invention [Problem to be solved by the invention]

[0018] The present invention has been made in light of the background of the prior art as described above, and aims to provide an electrode assembly having a folded plain portion structure that can prevent damage to a separator or active material layer when welding a current collector by ensuring a sufficient area for 10 or more plain portions to overlap in the radial direction of the electrode assembly when the plain portions exposed at both ends of the electrode assembly are folded.

[0019] Another object of the present invention is to provide an electrode assembly in which the electrolyte injection passage is not blocked even when the non-coating portion is bent.

[0020] Another object of the present invention is to provide an electrode assembly having improved energy density and reduced resistance.

[0021] It is yet another object of the present invention to provide a battery including an electrode assembly with an improved structure, a battery pack including the same, and a vehicle including the battery pack.

[0022] The technical problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems will be clearly understood by those skilled in the art from the following description of the invention. [Means for solving the problem]

[0023] To achieve the above object, one aspect of the present invention provides an electrode assembly in which a first electrode, a second electrode, and a separator interposed therebetween are wound around an axis to define a core and an outer circumferential surface, wherein the first electrode includes an uncoated portion at a long side end thereof that is exposed to the outside of the separator along a winding axis direction of the electrode assembly, and a portion of the uncoated portion is folded in a radial direction of the electrode assembly to form a folded surface region including overlapping layers of the uncoated portion, and a portion of the folded surface region has 10 or more stacked uncoated portions in the winding axis direction of the electrode assembly.

[0024] In one embodiment, the total number of winding turns of the first electrode is defined as n1, and the winding turn index k (a natural number from 1 to n1) at the kth winding turn position is divided by the total number of winding turns n1 to obtain the relative radial position R with respect to the winding turn index k. 1,k If we define it as follows, R satisfies the condition that the number of layers in the plain area is 10 or more. 1,k The ratio of the length of the radial direction section to the relative radial position section where the plain portion is folded can be at least 30%.

[0025] Preferably, the number of layers in the plain area must be 10 or more. 1,k The ratio of the length of the radial section to the relative radial position section where the non-coating portion is folded may be 30% to 85%.

[0026] In another embodiment, the second electrode may include an uncoated portion at a long side end portion exposed to the outside of the separator along the winding axis direction of the electrode assembly, a portion of the uncoated portion being folded in the radial direction of the electrode assembly to form a folded surface region including overlapping layers of the uncoated portion, and a portion of the folded surface region may have 10 or more stacked uncoated portions in the winding axis direction of the electrode assembly.

[0027] In still another embodiment, the total number of winding turns of the second electrode is defined as n2, and the winding turn index k (a natural number from 1 to n2) at the k-th winding turn position is divided by the total number of winding turns n2 to obtain the relative radial position R 2,k If we define it as follows, R satisfies the condition that the number of layers in the plain area is 10 or more. 2,k The ratio of the length of the radial direction section to the relative radial position section where the plain portion is folded may be at least 30%.

[0028] Preferably, the number of layers in the plain area must be 10 or more. 2,k The ratio of the length of the radial direction section to the relative radial position section where the non-coating portion is folded may be 30% to 85%.

[0029] In still another embodiment, in the winding structure of the first electrode, the relative radial position R 1,1 to the preset first relative radius position R 1,k* The height of the plain area in the section up to the relative radial position R of the winding turn number k*+1 1,k*+1 The height of the plain area in the section from to relative radius position 1 may be lower than the height of the plain area in the section from to relative radius position 1.

[0030] In still another embodiment, in the winding structure of the first electrode, the relative radial position R of the first winding turn 1,1 The first relative radial position R of the k*th winding turn preset from 1,k* The height of the plain portion in the section up to may be lower than the folded surface region formed by overlapping folded plain portions.

[0031] In still another embodiment, in the winding structure of the first electrode, the relative radial position R of the first winding turn 1,1 The first relative radial position R of the k*th winding turn from 1,k* The uncoated portion in the section up to does not need to be folded toward the core of the electrode assembly.

[0032] In yet another embodiment, in the winding structure of the second electrode, the relative radial position R of the first winding turn 2,1 The first relative radial position R of the k*th winding turn preset from 2,k* The height of the plain area in the section up to the k*+1th winding turn is the relative radial position R 2,k*+1 The height of the plain area in the section from to relative radius position 1 may be lower than the height of the plain area in the section from to relative radius position 1.

[0033] In yet another embodiment, the relative radial position R of the first winding turn 2,1 The first relative radial position R of the k*th winding turn preset from 2,k* The height of the plain portion in the section up to can be lower than the folded surface area formed by overlapping the folded plain portion.

[0034] In yet another embodiment, the relative radial position R of the first winding turn 2,1The first relative radial position R of the k*th winding turn preset from 2,k* The uncoated portion in the section up to does not need to be folded toward the core of the electrode assembly.

[0035] Preferably, the uncoated portion of the first electrode or the uncoated portion of the second electrode may be divided into a plurality of segments that can be bent independently.

[0036] Preferably, each of the plurality of segments has a geometric shape in which the upper region of the bend line has the bend line as its base, and the geometric shape may be one or more straight lines, one or more curved lines, or a combination thereof connected together.

[0037] In one form, the geometric shapes may have a stepped or continuous decrease in width from the base to the top.

[0038] In another embodiment, the lower interior angle formed by the base of the geometrical figure and the side that intersects with the base may be 60° to 85°.

[0039] In yet another embodiment, the lower interior angle of the plurality of segments may increase stepwise or continuously along a direction parallel to the winding direction of the electrode assembly.

[0040] In yet another embodiment, each of the plurality of segments has a trapezoidal shape in which the upper region of the bend line is set to the bend line as a base, and the radius of the winding turn in which the segment is arranged is set to r, and the arc length of the winding turn corresponding to the lower portion of the segment is set to L. arc , the lower interior angle of a pair of segments arranged adjacent to a winding turn of radius r when the assumption that the sides of the segments are parallel is applied is defined as θ assumption Then, the actual lower interior angle θ of the adjacently arranged pair of segments is real may satisfy the following formula 1. [Formula 1] θ real >θ assumption θ1=90°-360°×(L arc / 2πr)×0.5

[0041] In yet another embodiment, the arc length L of the winding turn corresponding to the lower portion of the segment based on the core center of the electrode assembly arc The corresponding inscribed angle may be 45° or less.

[0042] In still another embodiment, the overlapping ratio between adjacent electrode segments arranged in a winding turn of radius r based on the core center of the electrode assembly is expressed by the formula (θ real / θ assumption -1), the overlapping ratio of the two segments can be greater than 0 and less than or equal to 0.05.

[0043] In yet another embodiment, when an imaginary circle is drawn through adjacent pairs of segments arranged in a winding turn of radius r based on the core center of the electrode assembly, pairs of arcs passing through each segment may overlap.

[0044] In yet another embodiment, when the ratio of the length of the overlapping arc to the length of the arc passing through each segment is defined as the overlap ratio of the segment, the overlap ratio of the segment may be greater than 0 and not greater than 0.05.

[0045] In still another embodiment, in the winding structure of the first electrode, the relative radial position R of the first winding turn 1,1 The first relative radial position R of the k*th winding turn from 1,k* The height of the plain area in the section up to the relative radial position R 1,k*+1 The height of the uncoated portion in the section from the center to the relative radial position 1 may be lower than the height of the uncoated portion, and the uncoated portion may not be bent toward the core side.

[0046] In yet another embodiment, the relative radial position R 1,1 From R 1,k* The length of the first electrode corresponding to the relative radial position R 1,k*+1 The length of the first electrode may be 1% to 30% of the length of the first electrode corresponding to 1.

[0047] In still another embodiment, in the winding structure of the first electrode, the relative radial position R of the k*+1-th winding turn1,k*+1 Folded length of plain part fd 1,k*+1 is the relative radial position R of the first winding turn 1,1 k*th relative radial position R 1,k* The radial length of the axial direction ...

[0048] In still another embodiment, in the winding structure of the first electrode, the core radius of the electrode assembly is r c When the definition is given, 0.9r from the center of the core c The relative radial position R of the k*+1th winding turn in the section 1,k*+1 It is not blocked by the bent part of the plain area located in the section from to 1.

[0049] In yet another embodiment, the relative radial position R of the k*+1-th winding turn 1,k*+1 Folded length of plain part fd 1,k*+1 , the radius of the core r c , and the relative radial position R 1,k*+1 is the distance d from the center of the electrode assembly 1,k*+1 may satisfy the following formula 2. [Formula 2] fd 1,k*+1 +0.90×r c ≦d 1,k*+1

[0050] In still another embodiment, in the winding structure of the second electrode, the relative radial position R of the first winding turn 2,1 The first relative radial position R of the k*th winding turn from 2,k* The height of the plain area in the section up to the k*+1th winding turn is the relative radial position R 2,k*+1 The height of the uncoated portion in the section from the center to the relative radial position 1 may be lower than the height of the uncoated portion, and the uncoated portion may not be bent toward the core side.

[0051] In yet another embodiment, the relative radial position R 2,1 From R 2,k* The length of the second electrode corresponding to the relative radial position R 2,k*+1 The length of the second electrode corresponding to the relative radial position 1 may be 1% to 30%.

[0052] In still another embodiment, in the winding structure of the second electrode, the relative radial position R of the k*+1-th winding turn 2,k*+1 The folded length of the plain part located at fd 2,k*+1 is the relative radial position R of the first winding turn 2,1 The first relative radial position R of the k*th winding turn from 2,k* The radial length of the axial direction ...

[0053] In still another embodiment, in the winding structure of the second electrode, the core radius of the electrode assembly is r c When defined as 0.90r from the center of the core c The relative radial position R of the k*+1th winding turn in the section 2,k*+1 The uncoated portion of the second electrode located in the section from the first position to the relative radial position 1 is not blocked by the bent portion.

[0054] In yet another embodiment, the relative radial position R of the k*+1-th winding turn 2,k*+1 Folded length of plain part fd 2,k*+1 , the radius of the core r c , and the relative radial position R 2,k*+1 is the distance d from the center of the electrode assembly 2,k*+1 may satisfy the following Equation 3. [Formula 3] fd 2,k*+1 +0.90×r c ≦d 2,k*+1

[0055] In still another embodiment, in the winding structure of the first electrode, the relative radial position R of the k*+1-th winding turn 1,k*+1 Pre-set from

number

number

[0056] In yet another embodiment, the relative radial position R 1,k*+1 from

number

[0057] In still another embodiment, in the winding structure of the first electrode, a predetermined

number

number

number

[0058] In still another embodiment, in the winding structure of the second electrode, the relative radial position R of the k*+1-th winding turn 2,k*+1 Pre-set from

number

number

[0059] In yet another embodiment, the relative radial position R 2,k*+1 from

number

[0060] In still another embodiment, in the winding structure of the second electrode,

number

number

number

number

[0061] In yet another embodiment, in the winding structure of the first electrode, the uncoated portion bent in the radial direction of the electrode assembly is divided into a plurality of segments that can be bent independently, and at least one of the height in the winding axis direction and the width in the winding direction of the plurality of segments may increase stepwise individually or for each group along a direction parallel to the winding direction.

[0062] In yet another embodiment, in the winding structure of the second electrode, the uncoated portion bent in the radial direction of the electrode assembly is divided into a plurality of segments that can be bent independently, and at least one of the height in the winding axis direction and the width in the winding direction of the plurality of segments may increase stepwise individually or for each group along a direction parallel to the winding direction.

[0063] In yet another embodiment, each of the plurality of segments may satisfy at least one of the following conditions: a width of 1 mm to 11 mm in the winding direction, a height of 2 mm to 10 mm in the winding axial direction, and a spacing pitch of 0.05 mm to 1 mm in the winding direction.

[0064] In still another embodiment, cutting grooves may be interposed between the plurality of cut pieces, and a predetermined gap may be provided between a lower end of the cutting groove and the active material layer.

[0065] In yet another embodiment, the length of the gap may be between 0.2 mm and 4 mm.

[0066] In yet another embodiment, the plurality of segments form a plurality of segment groups along the winding direction of the electrode assembly, and the segments belonging to the same segment group may be substantially identical to each other in at least one of their width in the winding direction, their height in the winding axial direction, and their spacing pitch in the winding direction.

[0067] In yet another embodiment, the segments belonging to the same segment group may have at least one of their width in the winding direction, their height in the winding axial direction, and their separation pitch in the winding direction increased stepwise in one direction parallel to the winding direction of the electrode assembly.

[0068] In yet another embodiment, at least some of the plurality of segment groups may be arranged on the same winding turn of the electrode assembly.

[0069] In yet another embodiment, the folded surface region formed by the uncoated portion of the first electrode includes an increasing lamination number section and a uniform lamination number section from the outer periphery side to the core side of the electrode assembly, the increasing lamination number section being defined as a section in which the number of laminations in the uncoated portion increases from 1 to a maximum value, the uniform lamination number section being defined as a section from a radial position where the number of laminations in the uncoated portion reaches a maximum value to a radial position where folding of the uncoated portion begins, and the radial length of the uniform lamination number section may be 30% or more of the radial length from the winding turn where folding of the uncoated portion begins to the winding turn where folding of the uncoated portion ends.

[0070] In yet another embodiment, the folded surface region formed by the uncoated portion of the second electrode includes a lamination number increasing section and a lamination number uniform section from the outer periphery side to the core side of the electrode assembly, the lamination number increasing section being defined as a section in which the lamination number of the uncoated portion increases from 1 to a maximum value, the lamination number uniform section being defined as a section from a radial position where the lamination number of the uncoated portion reaches a maximum value to a radial position where folding of the uncoated portion begins, and the radial length of the lamination number uniform section may be 30% or more of the radial length from the winding turn where folding of the uncoated portion begins to the winding turn where folding of the uncoated portion ends.

[0071] In yet another embodiment, the thickness of the first electrode and the thickness of the second electrode may be 80 μm to 250 μm, and the spacing between the uncoated portions located on adjacent winding turns in the radial direction of the electrode assembly may be 200 μm to 500 μm.

[0072] In yet another embodiment, the thickness of the uncoated portion of the first electrode may be 10 μm to 25 μm.

[0073] In yet another embodiment, the thickness of the uncoated portion of the second electrode may be 5 μm to 20 μm.

[0074] In still another embodiment, in a portion of the folded surface region formed by the uncoated portion of the first electrode, the total thickness of the overlapping layer of the uncoated portion may be 100 μm to 975 μm.

[0075] In yet another embodiment, the uncoated portion of the first electrode is divided into a plurality of segments that can be independent of each other, and the first electrode includes a height-variable section where the height of the segments varies and a uniform height section where the height of the segments is uniform, and in a region of the folded surface region formed by bending the segments included in the uniform height section along the radial direction of the assembly, the ratio of the lamination thickness of the uncoated portion of the folded surface region to the height of the segments may be 1.0% to 16.3%.

[0076] In still another embodiment, in a portion of the folded surface region formed by the uncoated portion of the second electrode, the total thickness of the overlapping layers of the uncoated portion may be 50 μm to 780 μm.

[0077] In yet another embodiment, the uncoated portion of the second electrode is divided into a plurality of segments that can be independent of each other, and the second electrode includes a variable height section where the height of the segments varies and a uniform height section where the height of the segments is uniform, and in a region of the folded surface region formed by bending the segments included in the uniform height section along the radial direction of the assembly, the ratio of the lamination thickness of the uncoated portion of the folded surface region to the height of the segments may be 0.5% to 13.0%.

[0078] To achieve the above object, another aspect of the present invention provides an electrode assembly in which a first electrode, a second electrode, and a separator interposed therebetween are wound around an axis to define a core and an outer peripheral surface, wherein the first electrode includes a first uncoated portion at a long side end thereof that is exposed to the outside of the separator along the winding axis direction of the electrode assembly, and a portion of the first uncoated portion is folded in the radial direction of the electrode assembly to form a first folded surface region, and a laminate thickness of the first uncoated portion in a portion of the first folded surface region is 100 μm to 975 μm.

[0079] In one embodiment, the first uncoated portion of the first electrode is divided into a plurality of segments that can be independent of each other, and the first electrode includes a height-variable section where the height of the segments varies and a uniform height section where the height of the segments is uniform, and in a region of the folded surface region formed by bending the segments included in the uniform height section along the radial direction of the assembly, the ratio of the thickness of the laminate of the uncoated portion of the folded surface region to the height of the segments may be 1.0% to 16.3%.

[0080] In another embodiment, the second electrode includes a second uncoated portion at a long side end portion exposed to the outside of the separator along the winding axis direction of the electrode assembly, a portion of the second uncoated portion being folded in the radial direction of the electrode assembly to form a second folded surface region, and a laminate thickness of the second uncoated portion in a portion of the second folded surface region may be 50 μm to 780 μm.

[0081] In yet another embodiment, the second uncoated portion of the second electrode is divided into a plurality of segments that can be independent of each other, and the second electrode includes a height-variable section where the height of the segments varies and a uniform height section where the height of the segments is uniform, and in a region of the folded surface region formed by bending the segments included in the uniform height section along the radial direction of the assembly, the ratio of the thickness of the uncoated portion lamination in the folded surface region to the height of the segments may be 0.5% to 13.0%.

[0082] To achieve the above object, according to yet another aspect of the present invention, there is provided a battery comprising an electrode assembly in which a first electrode, a second electrode, and a separator interposed therebetween are wound around an axis to define a core and an outer circumferential surface, wherein at least one of the first electrode and the second electrode includes an uncoated portion at a long side end thereof that is exposed to the outside of the separator along a winding axis direction of the electrode assembly, at least a portion of the uncoated portion being folded in a radial direction of the electrode assembly to form a folded surface region, and a portion of the folded surface region has 10 or more uncoated portions stacked thereon. a battery housing that houses the electrode assembly and is electrically connected to one of the first electrode and the second electrode and has a first polarity; a sealing body that seals an open end of the battery housing; a terminal that is electrically connected to the other of the first electrode and the second electrode and has a surface exposed to the outside and has a second polarity; and a current collector that is welded to the folded surface region and electrically connected to the battery housing and one of the terminals, wherein the welded region of the current collector overlaps with the folded surface region where the number of layers of the plain portion is 10 or more.

[0083] In one embodiment, the first electrode includes a first uncoated portion at a long side end portion exposed to the outside of the separator along the winding axis direction of the electrode assembly, and the total number of winding turns of the first electrode is defined as n1, and the winding turn index k (a natural number from 1 to n1) at the k-th winding turn position is divided by the total number of winding turns n1 to obtain a relative radial position R with respect to the winding turn index k. 1,k If the number of layers of the first plain portion is defined as 10 or more, R 1,k The ratio of the length of the radial direction section to the length of the relative radial position section where the first uncoated portion is bent may be at least 30%.

[0084] In another embodiment, the second electrode includes a second uncoated portion at a long side end portion exposed to the outside of the separator along the winding axis direction of the electrode assembly, and the total number of winding turns of the second electrode is defined as n2, and the winding turn index k (a natural number from 1 to n2) at the k-th winding turn position is divided by the total number of winding turns n2 to obtain a relative radial position R with respect to the winding turn index k. 2,k If the number of layers of the second plain portion is defined as 10 or more, R 2,k The ratio of the length of the radial direction section to the relative radial position section where the second uncoated portion is folded may be at least 30%.

[0085] In yet another embodiment, the welding region of the current collector may overlap 50% or more with the folded surface region of the plain portion having 10 or more laminations.

[0086] Preferably, the welded area of ​​the current collector has a weld strength of 2 kgf / cm 2 It could be more than that.

[0087] Preferably, the welding regions may be spaced apart at a distance of 4 mm or more in the radial direction from the core center of the electrode assembly and 50% or less of the radius of the electrode assembly.

[0088] To achieve the above object, according to yet another aspect of the present invention, there is provided a battery comprising: an electrode assembly in which a first electrode, a second electrode, and a separator interposed therebetween are wound around an axis to define a core and an outer circumferential surface, the first electrode including a first uncoated portion at a long side end thereof, the first uncoated portion being exposed to the outside of the separator along a winding axis direction of the electrode assembly, a portion of the first uncoated portion being folded in a radial direction of the electrode assembly to form a first folded surface region, and a lamination thickness of the first uncoated portion in a portion of the first folded surface region being 100 μm to 975 μm; the battery housing includes a battery housing that houses a pole assembly and is electrically connected to one of the first electrode and the second electrode and has a first polarity; a sealing body that seals an open end of the battery housing; a terminal that is electrically connected to the other of the first electrode and the second electrode and has a surface exposed to the outside and has a second polarity; and a first current collector that is welded to the first bent surface region and electrically connected to the battery housing and one of the terminals, wherein the welded region of the first current collector overlaps a portion of the first bent surface region, where the lamination thickness of the first uncoated portion is 100 μm to 975 μm.

[0089] In yet another embodiment, the first uncoated portion of the first electrode is divided into a plurality of segments that can be independent of each other, the first electrode includes a height-variable section in which the height of the segments varies and a uniform height section in which the height of the segments is uniform, and in a region of the first folded surface region formed by folding the segments included in the uniform height section along the radial direction of the assembly, the ratio of the thickness of the uncoated portion lamination of the first folded surface region to the height of the segments may be 1.0% to 16.3%.

[0090] The welding strength of the welded area of ​​the first current collector is 2 kgf / cm 2 It could be more than that.

[0091] Preferably, the welded area of ​​the first current collector has a weld strength of 2 kgf / cm 2 It could be more than that.

[0092] In yet another embodiment, the second electrode includes a second uncoated portion at a long side end portion exposed to the outside of the separator along a winding axis direction of the electrode assembly, a portion of the second uncoated portion being bent in a radial direction of the electrode assembly to form a second folded surface region, a portion of the second folded surface region having a lamination thickness of the second uncoated portion of 50 μm to 780 μm, and a second current collector welded to the second folded surface region and electrically connected to the other of the battery housing and the terminal, and a welded region of the second current collector may overlap a portion of the second folded surface region having a lamination thickness of 50 μm to 780 μm.

[0093] In yet another embodiment, the second uncoated portion of the second electrode is divided into a plurality of segments that can be independent of each other, and the second electrode includes a height-variable section in which the height of the segments varies and a uniform height section in which the height of the segments is uniform, and in a region of the second folded surface region formed by bending the segments included in the uniform height section along the radial direction of the assembly, the ratio of the thickness of the uncoated portion lamination of the second folded surface region to the height of the segments may be 0.5% to 13%.

[0094] Preferably, the welding strength of the welded area of ​​the second current collector is 2 kgf / cm 2 It could be more than that.

[0095] In still another embodiment, the welding region of the first current collector may overlap 50% or more with a portion of the first folded surface region where the lamination thickness of the first uncoated portion is 100 μm to 975 μm.

[0096] In still another embodiment, the welding region of the second current collector may overlap 50% or more with a portion of the second folded surface region where the second uncoated portion has a lamination thickness of 50 μm to 780 μm.

[0097] In yet another embodiment, the welding region of the first current collector and the welding region of the second current collector may extend in a radial direction of the electrode assembly from positions spaced apart by substantially the same distance from a core center of the electrode assembly.

[0098] In yet another embodiment, the length of the welded region of the first current collector may be longer than the length of the welded region of the second current collector.

[0099] The above object can also be achieved by a battery pack including the above-described battery, and a vehicle including the same. [Effects of the Invention]

[0100] According to one aspect of the present invention, when the uncoated portions exposed at both ends of the electrode assembly are bent, a sufficient area is secured in the radial direction of the electrode assembly so that 10 or more uncoated portions overlap, thereby preventing damage to the separator and the active material layer even when the welding power is increased.

[0101] According to another aspect of the present 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 facilitating the electrolyte injection process and the welding process of the battery housing and the current collector.

[0102] According to yet another aspect of the present invention, an electrode assembly with improved energy density and reduced resistance can be provided by directly welding a folded surface area of ​​a non-coating portion to a current collector instead of using a strip-shaped electrode tab.

[0103] According to yet another aspect of the present invention, it is possible to provide a battery having a structure in which internal resistance is low and welding strength between a current collector and an uncoated portion is improved, and a battery pack and a vehicle including the same.

[0104] The present invention also provides various other effects, which will be described later with reference to the embodiments, but explanations of effects that can be easily inferred by ordinary skilled artisans will be omitted.

[0105] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention, serve to further understand the technical concepts of the present invention. Therefore, the present invention should not be interpreted as being limited to only the matters described in the drawings. [Brief explanation of the drawings]

[0106] [Figure 1] 1 is a plan view showing the structure of an electrode plate used in manufacturing a conventional tabless cylindrical battery. [Figure 2] 1 is a diagram showing a conventional electrode plate winding process for a tabless cylindrical battery. [Figure 3] 1 is a diagram showing a process of welding a current collector to a folded surface area of ​​a non-coating portion in a conventional tabless cylindrical battery. [Figure 4] 1 is a plan view showing a structure of an electrode plate according to an embodiment of the present invention; [Figure 5] 10 is a diagram illustrating definitions of width, height, and spacing pitch of segments according to an embodiment of the present invention. [Figure 6a] 10A and 10B are diagrams for explaining overlapping conditions of the segments according to an embodiment of the present invention. [Figure 6b] 10A and 10B are diagrams for explaining overlapping conditions of the segments according to an embodiment of the present invention. [Figure 7a] 3 is a view showing an upper cross-sectional structure of an electrode assembly before a folding structure of an uncoated portion is formed according to an embodiment of the present invention; [Figure 7b] 3 is a cross-sectional view illustrating a lower portion of an electrode assembly before a folding structure of an uncoated portion is formed according to an embodiment of the present invention; [Figure 8a] 1 is a cross-sectional view of an electrode assembly in which a folded surface region is formed by folding an uncoated portion according to an embodiment of the present invention; [Figure 8b] 1 is a perspective view of an electrode assembly in which a folded surface region is formed by folding an uncoated portion according to an embodiment of the present invention; [Figure 9a]This is a cross-sectional view showing the folded surface area formed when the segments of the first electrode are folded from the outer periphery to the core without overlapping in the circumferential direction in an electrode assembly with a radius of 22 mm included in a cylindrical battery of form factor 4680. [Figure 9b] This is a cross-sectional view showing the folded surface area formed by overlapping segments in the radial and circumferential directions when segments of a first electrode are bent from the outer periphery to the core while overlapping in the circumferential direction in an electrode assembly with a radius of 22 mm included in a cylindrical battery of form factor 4680. [Figure 10] 1 is a cross-sectional view of a cylindrical battery according to an embodiment of the present invention taken along the Y-axis direction. [Figure 11] 4 is a cross-sectional view of a cylindrical battery according to another embodiment of the present invention taken along the Y-axis direction. FIG. [Figure 12] FIG. 2 is a plan view showing the structure of a first current collector according to an embodiment of the present invention. [Figure 13] FIG. 3 is a perspective view showing the structure of a second current collector according to an embodiment of the present invention. [Figure 14] 1 is a plan view illustrating a state in which a plurality of cylindrical batteries are electrically connected together according to an embodiment of the present invention; [Figure 15] FIG. 15 is an enlarged partial view of FIG. 14 showing in detail the electrical connections of multiple cylindrical batteries. [Figure 16] 1 is a diagram illustrating a battery pack including a cylindrical battery according to an embodiment of the present invention. [Figure 17] 1 is a diagram illustrating a vehicle including a battery pack according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0107] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and words used in the specification and claims should not be interpreted as being limited to their ordinary and dictionary meanings, but should be interpreted as having meanings and concepts corresponding to the technical ideas of the present invention, in accordance with the principle that the inventors themselves can appropriately define the concepts of terms in order to best explain the invention.

[0108] Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiment of the present invention and do not represent the entire technical idea of ​​the present invention, and that there may be various equivalents and modifications that can be substituted for them at the time of this application.

[0109] The expression that two comparison objects are identical means that they are "substantially identical." Therefore, "substantially identical" may include deviations that are considered low in the art, for example, deviations within 5%. Furthermore, the expression that a parameter is uniform in a given region means that the parameter is uniform on average in that region.

[0110] Furthermore, although terms such as "first" and "second" are used to indicate various components, these terms are not intended to limit the components. These terms are used merely to distinguish one component from another, and unless otherwise specified, the first component can also be the second component.

[0111] Throughout the specification, unless otherwise stated, each element may be singular or plural.

[0112] When an arbitrary structure is placed "on (or under)" a component or "above (or below)" a component, it means not only that the arbitrary structure is placed in contact with the upper surface (or lower surface) of the component, but also that other structures may be interposed between the component and the arbitrary structure placed above (or below) the component.

[0113] Furthermore, when a component is said to be "coupled," "coupled," or "connected" to another component, it does not only mean that the components are directly coupled or connected to each other, but also that other components are "intervening" between the components, or that each component is "coupled," "coupled," or "connected" through other components.

[0114] Throughout the specification, unless otherwise specified, "A and / or B" means A, B, or A and B, and "C to D" means C or more and D or less, unless otherwise specified.

[0115] For ease of explanation, in this specification, the direction along the longitudinal direction of the winding shaft of the electrode assembly wound into a jelly roll is referred to as the axial direction (Y-axis direction). The direction surrounding the winding shaft is referred to as the circumferential direction or outer circumferential direction (X-axis direction). The direction approaching or moving away from the winding shaft is referred to as the radial direction. Of these, the direction approaching the winding shaft is referred to as the centripetal direction, and the direction moving away from the winding shaft is referred to as the centrifugal direction.

[0116] First, an electrode assembly according to an embodiment of the present invention will be described. The electrode assembly is a jelly-roll type electrode assembly having a structure in which sheet-like first and second electrodes are wound in one direction with a separator interposed therebetween. However, the present invention is not limited to the specific shape of the electrode assembly, and the electrode assembly may have any winding structure known in the art.

[0117] Preferably, at least one of the first electrode and the second electrode includes a non-coated portion on a long side edge in the winding direction where the active material is not coated, and at least a portion of the non-coated portion is used as an electrode tab.

[0118] FIG. 4 is a plan view showing the structure of an electrode 40 according to an embodiment of the present invention.

[0119] Referring to FIG. 4, the electrode 40 includes a current collector 41 made of metal foil and an active material layer 42. The metal foil may be aluminum or copper, and is appropriately selected depending on the polarity of the electrode 40. The active material layer 42 is formed on at least one surface of the current collector 41 and includes a plain portion 43 at the end of the long side in the winding direction X. The plain portion 43 is an area that is not coated with an active material. An insulating coating layer 44 may be formed at the boundary between the active material layer 42 and the plain portion 43. The insulating coating layer 44 is formed so that at least a portion of the insulating coating layer 44 overlaps the boundary between the active material layer 42 and the plain portion 43. The insulating coating layer 44 includes a polymer resin and may include an inorganic filler such as Al2O3. The area of ​​the plain portion 43 where the insulating coating layer 44 is formed also corresponds to the plain portion 43 because it does not include the active material layer 42.

[0120] Preferably, the folded portion of the uncoated portion 43 of the electrode 40 may include a plurality of divided segments 61. The height of the divided segments 61 may increase stepwise from the core side toward the outer periphery. The section where the height increases stepwise is the remaining area excluding the uncoated 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 the other portions.

[0121] The section 61 may be laser notched. The section 61 may be formed by known metal foil cutting processes such as ultrasonic cutting or punching.

[0122] When the electrode 40 is wound, each segment 61 may be bent at a bending line 62 in the radial direction of the electrode assembly, for example, toward the core. The core refers to a cavity at the center of the winding of the electrode assembly. Each segment 61 has a geometric shape with the bending line 62 as its base. In the geometric shape, the width of the bottom may be wider than the width of the top. In addition, in the geometric shape, the width of the bottom may increase gradually or in steps (not shown) toward the top. Preferably, the geometric shape may be trapezoidal.

[0123] In some embodiments, the geometric shape may include at least one straight line, at least one curve, or a combination thereof. For example, the geometric shape may be a polygon such as a triangle, a rectangle, a parallelogram, etc. For other examples, the geometric shape may be an arc shape such as a semicircle, a semiellipse, etc.

[0124] To prevent damage to the active material layer 42 and / or the insulating coating layer 44 during bending of the divided pieces 61, it is desirable to provide a predetermined gap between the lower end of the cut groove (D4 in FIG. 5) between the divided pieces 61 and the active material layer 42. This is because stress is concentrated near the lower end of the cut groove when the uncoated portion 43 is bent. The gap is preferably 0.2 mm to 4 mm. By adjusting the gap within the above numerical range, it is possible to prevent damage to the active material layer 42 and / or the insulating coating layer 44 near the lower end of the cut groove due to stress generated during bending of the divided pieces 61. In addition, the gap prevents damage to the active material layer 42 and / or the insulating coating layer 44 due to tolerances during notching or cutting of the divided pieces 61.

[0125] The plurality of segment pieces 61 may be arranged into a plurality of segment piece groups from the core side toward the outer periphery side. The width, height, and spacing pitch of the segment pieces belonging to the same segment piece group may be substantially the same.

[0126] FIG. 5 is a diagram illustrating definitions of the width, height, and spacing pitch of the segment pieces 61 according to an embodiment of the present invention.

[0127] Referring to FIG. 5, a cutting groove 63 is formed between the adjacent segment pieces 61. The corners of the lower portions of the cutting groove 63 have a rounded shape. That is, the cutting groove 63 includes a substantially linear bottom portion 63a and a rounded portion 63c. The rounded portion 63c connects the bottom portion 63a to a side edge 63b of the segment piece 61. Alternatively, the bottom portion 63a of the cutting groove 63 may be shaped like an arc. In this case, the side edge 63b of the segment piece 61 can be smoothly connected by the arc shape of the bottom portion 63a.

[0128] Preferably, the radius of curvature of the rounded portion 63c is greater than 0 and not greater than 0.5 mm, more preferably greater than 0 and not greater than 0.1 mm. More preferably, the radius of curvature of the rounded portion 63c is 0.01 mm to 0.05 mm. When the radius of curvature of the rounded portion 63c is within the above range, it is possible to prevent cracks from occurring below the cutting groove 63 while the electrode 40 is traveling during a winding process or the like.

[0129] The width D1, height D2, and spacing D3 of the divided pieces 61 are designed to sufficiently increase the number of layers of the plain portion 43 to prevent tearing of the plain portion 43 during bending and to improve welding strength, while also preventing abnormal deformation of the plain portion 43. Abnormal deformation refers to the plain portion below the bending point being unable to maintain a straight state and collapsing, resulting in irregular deformation. The bending point may be a point spaced 2 mm or less, preferably 1 mm or less, from the bottom end of the cutting groove 63, designated by reference symbol D4.

[0130] The width D1 of the segment 61 is defined as the length between two points where two straight lines extending from both side edges 63b of the segment 61 intersect with a straight line extending from the bottom 63a of the cutting groove 63. The height of the segment 61 is defined as the shortest distance between the top edge of the segment 61 and a straight line extending from the bottom 63a of the cutting groove 63. The spacing pitch D3 of the segment 61 is defined as the length between two points where a straight line extending from the bottom 63a of the cutting groove 63 intersects with a straight line extending from the two side edges 63b connected to the bottom 63a. When the side edges 63b and / or the bottom edge 63a are curved, the straight lines can be replaced with tangent lines extending from the side edges 63b and / or the bottom edge 63a.

[0131] Preferably, the width D1 of the divided piece 61 can be adjusted in the range of 1 mm to 11 mm. If D1 is less than 1 mm, when the divided piece 61 is bent toward the core, a non-overlapping area or an open space (gap) that is insufficient to ensure sufficient welding strength will be generated. On the other hand, if D1 exceeds 11 mm, the uncoated portion 43 near the bending point D4 may be torn by stress when the divided piece 61 is bent. The bending point D4 may be spaced apart from the bottom 63a of the cut groove 63. The distance may be 2 mm or less, preferably 1 mm or less. In addition, the height of the divided piece 61 can be adjusted in the range of 2 mm to 10 mm. If D2 is less than 2 mm, when the divided piece 61 is bent toward the core, a non-overlapping area or an open space (gap) that is insufficient to ensure sufficient welding strength will be generated. On the other hand, if D2 exceeds 10 mm, it is difficult to manufacture an electrode plate while maintaining uniform flatness of the uncoated portion in the winding direction X. That is, the uncoated portion becomes higher, causing swell. Furthermore, the spacing pitch D3 of the divided segments 61 can be adjusted within a range of 0.05 mm to 1 mm. If D3 is less than 0.05 mm, stress may cause cracks in the uncoated portion 43 near the bottom of the cut groove 63 when the electrode 40 travels during a winding process or the like. On the other hand, if D3 exceeds 1 mm, when the divided segments 61 are bent, the divided segments 61 may not overlap enough to ensure sufficient welding strength, or empty spaces (gaps) may occur.

[0132] On the other hand, when the current collector 41 of the electrode 40 is made of aluminum, it is more preferable to set the separation pitch 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, etc., it is possible to prevent cracks from occurring below the cutting grooves 63.

[0133] According to the experimental results, when the current collector 41 of the electrode 40 is an aluminum foil having a thickness of 15 μm and D3 is 0.5 mm or more, no cracks occur below the cutting groove 63 when the electrode 40 runs under the running conditions described above.

[0134] Further referring to FIG. 4, the width d of the core-side uncoated portion A A is designed under the condition that when the divided piece 61 is bent toward the core, it does not block 90% or more of the core of the electrode assembly.

[0135] As an example, the width d of the uncoated portion A on the core side A can increase in proportion to the bending length of the segment 61 of group 1. The bending length corresponds to the height of the segment 61 from the bending point (62 in FIG. 4).

[0136] In a specific example, when the electrode 40 is used to manufacture an electrode assembly for a cylindrical battery with a form factor of 4680, the width d of the core-side uncoated portion A is A can be set to 180 mm to 350 mm depending on the diameter of the core of the electrode assembly.

[0137] Preferably, the long side length L of the electrode 40 e Width d of the uncoated area A on the core side A The ratio d A / L e The ratio d can be 1% to 30%. In a large-sized cylindrical battery with a diameter of about 46 mm, the length of the electrode 40 is quite long, at 3000 mm to 5000 mm, so the core-side uncoated portion A can be designed to be sufficiently long. In a cylindrical battery with a form factor of 1865 or 2170, the length of the electrode plate is about 600 mm to 1200 mm. In a normal cylindrical battery, the ratio d A / L e It is difficult to design within the above numerical range.

[0138] In one example, the width of each segment group can be designed to form the same winding turn of the electrode assembly.

[0139] In another example, the width of each segment group can be designed to accommodate multiple winding turns of the electrode assembly.

[0140] In a variant, the width and / or height and / or spacing pitch of the segments 61 belonging to the same segment group may increase or decrease gradually and / or stepwise and / or irregularly within or between groups.

[0141] Groups 1 to 7 are merely examples of segment groups. The number of groups and the number of segment pieces 61 included in each group can be adjusted to maximize stress distribution during the bending of the uncoated portion 43, ensure sufficient welding strength, minimize gaps between the sides 63b of the segment pieces 61, and allow the segment pieces 61 to overlap in multiple layers along the radial direction of the electrode assembly without interfering with each other.

[0142] In one modification, a portion of the segments may be removed. In this case, the height of the uncoated portion where the segments have been removed may be the same as the height of the core-side uncoated portion A.

[0143] Preferably, the electrode 40 may be divided into a height variable section in which the height of the segments 61 varies along the long side direction, and a height uniform section in which the height of the segments 61 is uniform.

[0144] In the electrode 40, the variable height section is a section corresponding to groups 1 to 7, and the uniform height section is a section located on the outer periphery side of group 7.

[0145] In a specific example, the width d of the core-side plain portion A A The width of Group 1 may be 35-55% of the width of the core-side plain portion A. The width of Group 2 may be 120-150% of the width of Group 1. The width of Group 3 may be 110-135% of the width of Group 2. The width of Group 4 may be 75-90% of the width of Group 3. The width of Group 5 may be 120-150% of the width of Group 4. The width of Group 6 may be 100-120% of the width of Group 5. The width of Group 7 may be 90-120% of the width of Group 6.

[0146] The reason why the widths of Groups 1 to 7 do not show a consistent increase or decrease pattern is that although the width of the segments gradually increases from Group 1 to Group 7, the number of segments included in a group is limited to an integer, and the thickness of electrode 40 varies along the winding direction X. Therefore, the number of segments may decrease in a particular segment group. Therefore, the width of the group may show an irregular change pattern from the core side to the outer periphery side, as shown in the example above.

[0147] In the radial direction of the electrode assembly, when the winding direction widths for three consecutively adjacent segment groups are W1, W2, and W3, respectively, the electrode assembly may include a combination of segment groups in which W3 / W2 is smaller than W2 / W1.

[0148] In the specific example described above, this applies to groups 4 to 6. The width ratio of group 5 to group 4 is 120 to 150%, and the width ratio of group 6 to group 5 is 100 to 120%, which is smaller than 120 to 150%.

[0149] Preferably, the lower interior angle θ of the plurality of segment pieces 61 increases from the core side toward the outer periphery. The lower interior angle θ corresponds to the angle formed by a line passing through the bend curve (62 in FIG. 4) and a line (or a tangent) extending from the side edge 63b of the segment piece 61. If the segment piece 61 is asymmetric, the left interior angle and the right interior angle may be different.

[0150] As the radius of the electrode assembly increases, the radius of curvature also increases. If the lower interior angle θ of the segment 61 increases with the radius of the electrode assembly, stresses occurring in the radial and circumferential directions when the segment 61 is bent can be alleviated. Furthermore, as the lower interior angle θ increases, the overlapping area with the inner segment 61 when the segment 61 is bent and the number of layers of the segment 61 also increase, thereby ensuring uniform welding strength in the radial and circumferential directions and enabling the bent surface area to be formed flat.

[0151] Preferably, by adjusting the lower interior angle θ as the radius of the electrode assembly increases, the segment pieces 61 can overlap not only in the radial direction but also in the circumferential direction when bent.

[0152] Figures 6(a) and (b) show examples in which, in any winding turn of radius r based on the core center, the sides of the segment 61 bent toward the core side of the electrode assembly are spaced apart and parallel to each other, and examples in which the sides of the bent segment 61 intersect each other.

[0153] 6, a pair of adjacent segments 61 are arranged in a winding turn of radius r relative to the core center O of the electrode assembly. The width and height of adjacent segments 61 are substantially the same.

[0154] In Figure 6(a), the lower interior angle θ assumption is the angle when the sides of the segment 61 are assumed to be substantially parallel. assumption is the arc length L corresponding to the lower part of the segment 61 arc On the other hand, θ real is the actual lower interior angle when the sides of adjacent segments 61 intersect.

[0155] Preferably, the lower interior angle θ assumption and θ real satisfies the following formula 1, the segments 61 arranged on the winding turns positioned at a radius r with respect to the core center O can overlap each other in the circumferential direction. [Formula 1] θ real >θ assumption θ assumption =90°-360°×(L arc / 2πr)×0.5 θ real >90°-360°×(L arc / 2πr)×0.5 Here, r is the radius of the winding turn on which the segment 61 is disposed relative to the core center of the electrode assembly. L arcis the length of the arc (solid line) corresponding to the lower part (dotted line) of the segment in a circle with radius r, and is uniquely determined from the width D1 of the segment 61. "360° x (L arc / 2πr) is the inscribed angle α of the arc (solid line) corresponding to the lower part (dotted line) of the arc segment 61. "360° x (L arc / 2πr)×0.5" is the angle between line segment OB and line segment OA in right-angled triangle OAB. 90°-360°×(L arc / 2πr)×0.5 is the angle between the line segments OA and AB in the right triangle OAB, and the lower interior angle θ of the segment 61 assumption corresponds approximately to

[0156] Preferably, for any winding turn radius r, L arc The inclined angle α of each of the circular segments 61 may be 45° or less. If the inclined angle α of each of the circular segments 61 exceeds 45°, the circular segments 61 will not be bent smoothly. Therefore, at any radius r, L arc is greater than 1 mm, which is the lower limit of D1, and has a length of (45 / 360) × (2πr) or less.

[0157] The inclined angle α may vary depending on the radius of the winding turn on which the segment 61 is located. In one embodiment, the inclined angle α of the segment 61 may increase gradually or stepwise along the radial direction of the electrode assembly while satisfying the above-mentioned numerical range conditions, or vice versa. In another embodiment, the inclined angle α of the segment 61 may increase gradually or stepwise along the radial direction of the electrode assembly while satisfying the above-mentioned numerical range conditions, and then decrease gradually or stepwise along the radial direction of the electrode assembly while satisfying the above-mentioned numerical range conditions, or vice versa. In yet another embodiment, the inclined angle α of the segment 61 may remain substantially constant along the radial direction of the electrode assembly while satisfying the above-mentioned numerical range conditions.

[0158] Preferably, when the width D1 of the portion 61 in the winding direction changes along the winding direction, the circumferential angle α of the portion 61 is 45° or less, and the width D1 of the portion 61 in the winding direction can be in the range of 1 mm to 11 mm.

[0159] For example, if r is 20 mm and the inclined angle α is 30°, L arc is 10.5 mm, and θ assumption is approximately 75°. As another example, if r is 25 mm and the inscribed angle α is 25°, then L arc is 10.9 mm, and θ assumption is approximately 77.5°.

[0160] Preferably, at any winding turn radius r, (θ real / θ assumption θ −1) can be defined as the overlap ratio of the component segments 61 in the circumferential direction. The overlap ratio of the component segments 61 is preferably greater than 0 and less than or equal to 0.05. assumption is the circular arc L with a winding turn radius r arc If the overlapping ratio of the segment pieces 61 is greater than 0.05, the side edges of the segment pieces 61 may interfere with each other when they are bent, and they may not be bent smoothly.

[0161] The degree of overlap of the segment pieces 61 increases in proportion to the overlap rate. If the segment pieces 61 overlap each other along the circumferential direction of the winding turn, the number of stacked segment pieces 61 when the segment pieces 61 are folded can be further increased. An embodiment of this will be described later.

[0162] Preferably, when the electrode 40 is used to manufacture an electrode assembly for a cylindrical battery with a form factor of 4680, the core radius is 4 mm, and the height of the segment closest to the core is 3 mm, the lower interior angle of the segment 61 may increase stepwise in the range of 60° to 85° as the radius of the electrode assembly increases from 7 mm to 22 mm.

[0163] The radius range and the lower interior angle range can be determined from the design specifications of the form factor, the diameter of the core, the height of the segment closest to the core, the width D1 of the segment 61, and the overlap ratio.

[0164] On the other hand, the condition for overlapping of the segments can be changed as follows. That is, as shown in FIG. 6(b), when a virtual circle passing through a pair of adjacent segments 61 is drawn with the core center O of the electrode 40 as a reference, an arc e passing through each segment is formed. 1- e2 and e 3- If the arcs e4 overlap each other, the adjacent arc segments 61 may overlap each other. The overlapping ratio of the arc segments 61 is calculated by drawing multiple imaginary circles with different radii. 1- e2 (or e 3- e4) the length of the overlapping arc e 2- The overlap ratio of the second segment 61 may be greater than 0 and less than or equal to 0.05.

[0165] The shape of the segment 61 may be changed depending on the position. For example, a round shape (e.g., semicircular, semi-elliptical, etc.) that is advantageous for stress dispersion may be applied to a section where stress is concentrated, and a polygonal shape (e.g., square, trapezoid, parallelogram, etc.) with the largest possible area may be applied to a section where stress is relatively low.

[0166] The uncoated portion separation structure can also be applied to the core-side uncoated portion A. However, if a separation structure is applied to the core-side uncoated portion A, there is a risk of reverse forming, in which the ends of the core-side uncoated portion A bend toward the outer periphery when the separation pieces are bent depending on the radius of curvature of the core. Therefore, it is preferable not to apply a separation structure to the core-side uncoated portion A, or, even if a separation structure is applied, to adjust the width, height, and / or spacing of the separation pieces 61 to a level that does not cause reverse forming, taking into account the radius of curvature of the core.

[0167] The electrode plate structure of the above-described embodiment (variant) may be applied to a first electrode and / or a second electrode having different polarities included in a jelly roll-type electrode assembly. Furthermore, when the electrode plate structure of the embodiment (variant) is applied to one of the first electrode and the second electrode, a conventional electrode plate structure may be applied to the other. Furthermore, the electrode plate structures applied to the first electrode and the second electrode may not be the same, but may be different.

[0168] As an example, when the first electrode and the second electrode are a positive electrode and a negative electrode, respectively, any one of the embodiments (variants) may be applied to the first electrode, and a conventional electrode structure (see FIG. 1) may be applied to the second electrode.

[0169] As another example, when the first electrode and the second electrode are a positive electrode and a negative electrode, respectively, any one of the embodiments (variants) may be selectively applied to the first electrode, and any one of the embodiments (variants) may be selectively applied to the second electrode.

[0170] In the present invention, the positive electrode active material coated on the positive electrode and the negative electrode active material coated on the negative electrode may be any active material known in the art without any limitation.

[0171] As an example, the positive electrode active material has the general chemical formula A[A x M y ]O 2+z (A includes at least one element of Li, Na, and K; M includes at least one element selected from Ni, Co, Mn, Ca, Mg, Al, Ti, Si, Fe, Mo, V, Zr, Zn, Cu, Al, Mo, Sc, Zr, Ru, and Cr; x≧0, 1≦x+y≦2, −0.1≦z≦2; the stoichiometric coefficients x, y, and z are selected to maintain electroneutrality of the compound).

[0172] As another example, the positive electrode active material may be an alkali metal compound xLiM disclosed in U.S. Pat. No. 6,677,082, U.S. Pat. No. 6,680,143, etc. 1 O2.(1-x)Li2M 2 O3(M 1 contains at least one element having an average oxidation state of 3; M 2 contains at least one element having an average oxidation state of 4; 0≦x≦1).

[0173] In yet another example, the positive electrode active material may be a compound represented by the general chemical formula Li a M 1 x Fe 1-x M2 y P 1-y M 3 z O 4-z (M 1 contains at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg and Al; M 2 contains at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg, Al, As, Sb, Si, Ge, V and S; M 3 contains a halogen group element selectively containing F; 0 < a ≤ 2, 0 ≤ x ≤ 1, 0 ≤ y < 1, 0 ≤ z < 1; the stoichiometric coefficients a, x, y and z are selected so that the compound maintains electrical neutrality), or it may be a lithium metal phosphate represented by Li3M2(PO4)3 [M contains at least one element selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Al, Mg and Al].

[0174] Desirably, the positive electrode active material may contain primary particles and / or secondary particles formed by aggregating primary particles.

[0175] As an example, as the negative electrode active material, a carbon material, a lithium metal or a lithium metal compound, silicon or a silicon compound, tin or a tin compound, etc. can be used. Metal oxides such as TiO2 and SnO2 with a potential of less than 2V can also be used as the negative electrode active material. As the carbon material, both low-crystalline carbon and high-crystalline carbon can be used.

[0176] As the separation membrane, a porous polymer film, for example, a porous polymer film made of a polyolefin-based polymer such as a polyethylene homopolymer, a polypropylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, an ethylene / methacrylate copolymer, etc., can be used alone or by laminating these. As another example, the separation membrane can use a normal porous non-woven fabric, for example, a non-woven fabric made of high-melting glass fibers, polyethylene terephthalate fibers, etc.

[0177] At least one surface of the separator may include a coating layer of inorganic particles. Alternatively, the separator itself may be made of a coating layer of inorganic particles. The particles constituting the coating layer may have a structure in which they are bound with a binder so that there is interstitial volume between adjacent particles.

[0178] The inorganic particles may be made of an inorganic material having a dielectric constant of 5 or more. Non-limiting examples of the inorganic particles include Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT), PB(Mg3Nb 2 / 3 )O3-PbTiO3 (PMN-PT), BaTiO3, hafnia (HfO2), SrTiO3, TiO2, Al2O3, ZrO2, SnO2, CeO2, MgO, CaO, ZnO, and Y2O3.

[0179] The electrode assembly according to the embodiment of the present invention is a jelly-roll type electrode assembly 80 in which the electrode 40 according to the embodiment is applied to a first electrode (positive electrode) and a second electrode (negative electrode). However, the present invention is not limited to the specific form of the electrode assembly.

[0180] 7a and 7b are views showing the upper and lower cross-sectional structures of electrode assembly 80 before the bent structure of uncoated portions 43a and 43a' is formed according to an embodiment of the present invention, respectively. Also, FIGS. 8a and 8b are a cross-sectional view and a perspective view, respectively, of electrode assembly 80 after uncoated portions 43a and 43a' are bent to form a folded surface region F according to an embodiment of the present invention.

[0181] The electrode assembly 80 can be manufactured using the winding method described with reference to FIG. 2. For ease of explanation, the protruding structure of the uncoated portions 43a, 43a' extending outward from the separator is shown in detail, and the winding structure of the separator is not shown in detail. The uncoated portion 43a protruding upward from the electrode assembly 80 extends from the first electrode 40. The uncoated portion 43a' protruding downward from the electrode assembly 80 extends from the second electrode 40'. The ends of the separator are indicated by dotted lines.

[0182] The varying heights of uncoated portions 43a, 43a' are shown schematically. That is, the heights of uncoated portions 43a, 43a' may vary irregularly depending on the cutting position in the cross section. For example, if the sides of trapezoidal segment 61 are cut, the height of the uncoated portions in the cross section will be lower than the height of segment 61 (D2 in FIG. 4). Also, uncoated portions 43a, 43a' are not shown at the points where the cutting grooves (63 in FIG. 5) are cut.

[0183] Hereinafter, the structural features of the uncoated portion 43a of the first electrode 40 will be described in detail with reference to the drawings. Preferably, the uncoated portion 43a' of the second electrode 40' may have substantially the same features as the uncoated portion 43a of the first electrode 40.

[0184] 7a, 7b, 8a and 8b, the uncoated portions 43a, 43a' of the first electrode 40 and the second electrode 40' are folded in the radial direction to form a folded surface region F.

[0185] In the winding structure of the first electrode 40, the total number of winding turns of the first electrode 40 is n1, and the winding turn number index k (a natural number from 1 to n1) of the kth winding turn is divided by the total number of winding turns n1 to determine the relative radial position R of the kth winding turn. 1,k When the number of layers of the non-coating portion 43a is defined as 10 or more, the relative radial position R 1,k The radial length of the section is 30% or more of the radial length of the winding turn in which the segment is included.

[0186] For reference, the relative radial position of the first winding turn is 1 / n1 because the winding turn number index is 1. The relative radial position of the kth winding turn is k / n1. The relative radial position of the last n1th winding turn is 1. That is, the relative radial position increases from 1 / n1 to 1 from the core side of the electrode assembly 80 toward the outer periphery.

[0187] In the winding structure of the second electrode 40′, the total number of winding turns of the second electrode 40′ is n2, and the winding turn number index k (a natural number from 1 to n2) at the kth winding turn position is divided by the total number of winding turns n2 to determine the relative radial position R of the kth winding turn. 2,k When the relative radius position R is defined as the number of layers of the folded part of the plain part is 10 or more, 2,k The radial length of the section is 30% or more of the radial length of the winding turn in which the segment is arranged.

[0188] For reference, the relative radial position of the first winding turn is 1 / n2 because the winding turn number index is 1. The relative radial position of the kth winding turn is k / n2. The relative radial position of the last n2th winding turn is 1. That is, the relative radial position increases from 1 / n2 to 1 from the core side of the electrode assembly 80 toward the outer periphery.

[0189] Preferably, the winding turn index k of the first electrode 40 and the winding turn index k of the second electrode 40' should be understood as variables that can be assigned different values.

[0190] When the uncoated portions 43a, 43a' are bent in the radial direction, bent surface regions F are formed on the top and bottom of the electrode assembly 80, as shown in FIGS. 8a and 8b.

[0191] 8a and 8b, a plurality of the segments 61 are folded toward the core C of the electrode assembly 80 and overlap each other in the radial direction.

[0192] The number of stacked segments 61 can be defined as the number of segments 61 that intersect with an imaginary line drawn from the winding axis direction (Y-axis direction) at any radius point on the folded surface region F.

[0193] Preferably, the number of stacked segments 61 may be 10 or more in a radial section of at least 30% based on the radial length R1 of the winding turn including the segment 61, in order to sufficiently increase the welding strength between the folded surface region F and the current collector and prevent damage to the separator and active material layer during the welding process.

[0194] The current collector may be laser welded to the folded surface region F of the uncoated portions 43a, 43a'. Alternatively, other known welding techniques, such as resistance welding, may be used. When laser welding is used, it is desirable to increase the laser output to ensure sufficient weld strength. If the laser output is increased, the laser may penetrate the overlapping region of the uncoated portions 43a, 43a' and penetrate into the electrode assembly 80, damaging the separator and active material layer. Therefore, to prevent penetration by the laser, it is desirable to increase the number of uncoated portions 43a, 43a' stacked in the welding region above a certain level. In order to increase the number of uncoated portions 43a, 43a' stacked, the height of the divided segments 61 must be increased. However, increasing the height of the divided segments 61 may cause swelling of the uncoated portions 43a, 43a' during the manufacturing process of the electrode 40. Therefore, it is desirable to adjust the height of the divided segments 61 to an appropriate level, preferably between 2 mm and 10 mm.

[0195] By designing the radius section in the folded surface region F where the number of stacked segments 61 is 10 or more to be 30% or more relative to R1 and laser welding the region where 10 or more stacked segments 61 are present to the current collector, the overlapping portions of the plain area can adequately mask the laser even when the laser output is increased, preventing damage to the separator and active material layer by the laser. Furthermore, because the number of stacked segments 61 is high in the region irradiated with the laser, weld beads are formed with sufficient volume and thickness. This ensures sufficient weld strength and reduces resistance at the weld interface.

[0196] The laser output during welding of the current collector can be determined by the desired weld strength between the folded surface region F and the current collector. The weld strength increases in proportion to the number of layers of the plain portions 43a, 43a'. This is because the volume of the weld bead formed by the laser increases as the number of layers of the plain portions 43a, 43a' increases.

[0197] Preferably, the welding strength is 2 kgf / cm 2 More preferably, 4kgf / cm 2 If the weld strength satisfies the above numerical range, the physical properties of the weld interface will not be deteriorated even if the electrode assembly 80 is subjected to severe vibrations in the axial and / or radial directions of the winding, and the resistance of the weld interface can be reduced due to the sufficient volume of the weld beads. The laser power required to achieve the above weld strength conditions varies depending on the laser device, but can be appropriately adjusted within the range of 250W to 320W or within the range of 40% to 100% of the maximum laser power specification.

[0198] The weld strength is the tensile force per unit area of ​​the current collector (kgf / cm) when the current collector begins to separate from the folded surface area F. 2 ) can be defined as the welding strength. Specifically, after welding of the current collector is completed, a tensile force is applied to the current collector and the strength is gradually increased. As the tensile force increases, the uncoated portions 43a, 43a' begin to separate from the weld interface. The tensile force applied to the current collector at this time divided by the area of ​​the current collector is the weld strength.

[0199] Preferably, the first electrode 40 includes a current collector (foil) 41 and an active material coating layer 42 formed on at least one surface thereof, the electrode current collector 41 having a thickness of 10 μm to 25 μm, and the spacing between adjacent wound turns in the radial direction of the electrode assembly 80 may be 200 μm to 500 μm. Preferably, the current collector 41 may be made of aluminum.

[0200] The second electrode 40' includes a current collector (foil) and an active material coating layer formed on at least one surface thereof, and the current collector may have a thickness of 5 μm to 20 μm, and the spacing between adjacent winding turns in the radial direction of the electrode assembly 80 may be 200 μm to 500 μm. The current collector may be made of copper.

[0201] 4, 7a, and 7b, in the winding structure of the first electrode 40, the relative radial position R 1,1 to the preset first relative radius position R 1,k* The height of the plain area in the section up to the relative radial position R of the winding turn number k*+1 1,k*+1 The height of the plain area in the section from the relative radius position R to the relative radius position 1 may be lower than that of the plain area in the section from the relative radius position R 1,1 to the preset first relative radius position R 1,k* The height of the uncoated area in the section up to corresponds to the height of the uncoated area in the core-side uncoated area A (see Figure 4).

[0202] In the winding structure of the first electrode 40, if there is a winding turn on the outer periphery that does not include a segment 61, the relative radial position 1 may correspond to the relative radial position of the outermost winding turn that includes the segment 61.

[0203] Preferably, in the winding structure of the first electrode 40, the relative radial position R 1,1 to the first relative radial position R 1,k* The height of the plain portion in the section up to can be lower than the folded surface region F formed by overlapping the folded plain portion.

[0204] Preferably, in the winding structure of the first electrode 40, the relative radial position R 1,1 to the first relative radial position R 1,k* The uncoated portion in the section up to does not need to be folded toward the core of the electrode assembly 80.

[0205] Similar to the first electrode 40, the second electrode 40′ has a winding structure with a relative radial position R 2,1 to the preset first relative radius position R 2,k* The height of the plain area in the section up to the relative radial position R of the winding turn k*+12,k*+1 The height of the plain area in the section from to relative radius position 1 may be lower than the height of the plain area in the section from to relative radius position 1.

[0206] In the winding structure of the second electrode 40', if there is a winding turn on the outer periphery that does not include a segment 61, the relative radial position 1 may correspond to the relative radial position of the outermost winding turn that includes the segment 61.

[0207] In addition, the relative radial position R 2,1 to the preset first relative radius position R 2,k* The height of the plain portion in the section up to can be lower than the folded surface region F formed by overlapping the folded plain portion.

[0208] Preferably, the relative radial position R 2,1 to the first relative radial position R 2,k* The uncoated portion in the section up to does not need to be folded toward the core of the electrode assembly.

[0209] Preferably, in the winding structure of the second electrode 40′, the relative radial position R 2,1 to the first relative radial position R 2,k* The height of the plain area in the section up to the relative radial position R 2,k*+1 The height of the uncoated portion in the section from the center to the relative radial position 1 may be lower than the height of the uncoated portion, and the uncoated portion may not be bent toward the core side.

[0210] In the winding structure of the first electrode 40, the relative radial position R 1,k*+1 Folded length of plain part fd 1,k*+1 is the relative radial position R 1,1 relative radial position R 1,k* Therefore, when the core C of the electrode assembly 80 is at the relative radial position R 1,k*+1 10. The bent portion of the non-coated portion 43a located in the section from the first radial position to the first radial position is not blocked.

[0211] Alternatively, the core C of the electrode assembly 80 may have a radius r c Based on this, 90% or more of the relative radius position R 1,k*+1The core C is not closed by the bent portion of the uncoated portion 43a located in the section from the relative radial position 1 to the relative radial position 1. That is, the core C has a radius of at least 0 to 0.9r. c The radius section corresponding to is not closed by the bent portion of the non-coated portion 43a.

[0212] Preferably, the relative radial position R 1,k*+1 The folded length fd of the plain portion 43a located at 1,k*+1 , the radius of the core r c , and the relative radial position R 1,k*+1 is the distance d away from the center of the core C 1,k*+1 may satisfy the following equation 2. [Formula 2] fd 1,k*+1 +0.9×r c ≦d 1,k*+1

[0213] Preferably, in the winding structure of the second electrode 40′, the relative radial position R 2,1 to the first relative radial position R 2,k* The height of the plain area in the section up to the relative radial position R 2,k*+1 The height of the uncoated portion in the section from the center to the relative radial position 1 may be lower than the height of the uncoated portion, and the uncoated portion may not be bent toward the core side.

[0214] In the winding structure of the second electrode 40′, the relative radial position R 2,k*+1 The folded length of the plain part located at fd 2,k*+1 is the relative radial position R 2,1 to the first relative radial position R 2,k* Therefore, the length of the core C of the electrode assembly 80 can be shorter than the length of the core C to the relative radial position R 2,k*+1 The folded portion of the plain portion located in the section from to relative radius position 1 is not blocked.

[0215] Alternatively, the core C of the electrode assembly 80 may have a radius r c Based on this, 90% or more of the relative radius position R 2,k*+1 The folded portion of the plain portion 43a' is not closed.

[0216] Preferably, the relative radial position R 2,k*+1The folded length fd of the plain portion 43a' located at 2,k*+1 , the radius of the core r c , and the relative radial position R 2,k*+1 is the distance d away from the center of the core C 2,k*+1 may satisfy the following Equation 3: [Formula 3] fd 2,k*+1 +0.9×r c ≦d 2,k*+1

[0217] Preferably, the first electrode 40 has a predetermined winding structure.

number

number

number

[0218] On the other hand, in the winding structure of the first electrode 40, the relative radial position R 1,k*+1 Pre-set from

number

number

number

[0219] For example, in the winding structure of the first electrode 40 with a radius of 22 mm, the radial length of the height variable section of the segment is defined as H1, and the radius (Rr c ) is the ratio of H1 to the height variable section (H1 / (Rr c )), the ratio of the height variable section can be calculated as follows by rounding to the nearest decimal place:

[0220] In Example 1, R is 22 mm, and the core radius r c is 5mm, Rr c The height of the segment 61 can be changed in eight steps from 2 mm to 10 mm in the radius range of 7 mm to 15 mm. After the radius reaches 15 mm, the height of the segment 61 is maintained at 10 mm. Since H1 is 8 mm, the ratio of the height variable section can be 47% (8 mm / 17 mm).

[0221] In Example 2, R and r c is the same as in Example 1. The height of the minute segment 61 can be changed in seven steps from 2 mm to 9 mm in the radius range of 7 mm to 14 mm. After the radius reaches 14 mm, the height of the minute segment 61 is maintained at 9 mm. Since H1 is 7 mm, the ratio of the height variable section can be 41% (7 mm / 17 mm).

[0222] In Example 3, R and r c is the same as in Example 1. The height of the minute segment 61 can be changed in six stages from 2 mm to 8 mm in the radius range of 7 mm to 13 mm. After the radius reaches 13 mm, the height of the minute segment 61 is maintained at 8 mm. Since H1 is 6 mm, the ratio of the height variable section can be 35% (6 mm / 17 mm).

[0223] In Example 4, R and r c is the same as in Example 1. The height of the minute segment 61 can be changed in five stages from 2 mm to 7 mm in the radius range of 7 mm to 12 mm. After the radius reaches 12 mm, the height of the minute segment 61 is maintained at 7 mm. Since H1 is 5 mm, the ratio of the height variable section can be 29% (5 mm / 17 mm).

[0224] In Example 5, R and r c is the same as in Example 1. The height of the segment 61 can be changed in four stages from 2 mm to 6 mm in the radius range of 7 mm to 11 mm. After the radius reaches 11 mm, the height of the segment 61 is maintained at 6 mm. Since H1 is 4 mm, the ratio of the height variable section can be 24% (4 mm / 17 mm).

[0225] In Example 6, R and r c is the same as in Example 1. The height of the minute segment 61 can be changed in three stages from 2 mm to 5 mm in the radius range of 7 mm to 10 mm. After the radius reaches 10 mm, the height of the minute segment 61 is maintained at 5 mm. Since H1 is 3 mm, the ratio of the height variable section can be 18% (3 mm / 17 mm).

[0226] In Example 7, R and r c is the same as in Example 1. The height of the segment 61 can be changed in two stages from 2 mm to 4 mm in the radius range of 7 mm to 9 mm. After the radius reaches 9 mm, the height of the segment 61 is maintained at 4 mm. Since H1 is 2 mm, the ratio of the height variable section can be 12% (2 mm / 17 mm).

[0227] In Example 8, R and r c is the same as in Example 1. The height of the segment 61 can be varied in one step from 2 mm to 3 mm in the radius range of 7 mm to 8 mm. After the radius reaches 8 mm, the height of the segment 61 is maintained at 3 mm. Since H1 is 1 mm, the ratio of the height variable section can be 6% (1 mm / 17 mm).

[0228] In summary, R is 22mm, r c When the radius is 5 mm, and the height of the segment changes in one of 1 to 8 steps in the range of 2 mm to 10 mm in the section of 7 mm to 15 mm radius, the ratio of the height variable section can be 6% to 47%.

[0229] The range of the ratio of the height variable section is determined by the radius r of the core C. cThe calculation method is similar to that described above, so only the results are described.

[0230] For example, R is 22 mm, r c When the radius is 4 mm, and the height of the segment changes stepwise in one of 1 to 8 steps in the range of 2 mm to 10 mm in the section of radius 6 mm to 14 mm, the ratio of the height variable section can be 6% to 44%.

[0231] Another example is when R is 22mm and r c When the radius is 3 mm, and the height of the segment changes stepwise in one of 1 to 8 steps in the range of 2 mm to 10 mm in the section of 5 mm to 13 mm radius, the ratio of the height variable section can be 5% to 42%.

[0232] As another example, if R is 22 mm and r c When the radius is 2 mm, the height of the segment changes stepwise in one of 1 to 8 steps in the range of 2 mm to 10 mm in the section of 4 mm to 12 mm radius, the ratio of the height variable section can be 5% to 40%.

[0233] From the above calculation example, the radius r of the core C c When the radius of the electrode assembly 80 is constant, the upper and lower limits of the ratio of the height variable section are determined by the radius r of the core C. c decreases as

[0234] Meanwhile, the upper and lower limits of the ratio of the height variable section may vary depending on the width of height change and the number of height changes of the segment 61 per 1 mm increase in radius.

[0235] As an example, when the height of the minute segment 61 changes by 0.2 mm per 1 mm increase in radius, the lower and upper limits of the ratio of the height variable section are 1% and 9%, respectively.

[0236] As another example, when the height of the minute segment 61 changes by 1.2 mm per 1 mm increase in radius, the lower and upper limits of the ratio of the height variable section are 6% and 56%, respectively.

[0237] From the above examples, it is preferable that the ratio of the height variable section is 1% to 56%. When the ratio of the height variable section of the sub-segment 61 satisfies the above numerical range, the ratio of the radial length of the relative radial position where the number of layers of the plain section is 10 or more can be at least 30% of the radial length R1 of the winding turn including the sub-segment 61. As will be described later, such a configuration provides useful effects in terms of the welding strength and resistance of the current collector.

[0238] 4 and 7b, the winding structure of the second electrode 40′ also has a relative radial position R 2,k*+1 Pre-set from

number

number

number

[0239] In the winding structure of the second electrode 40′, the radial length of the height variable section is defined as H2, and the radius (Rr c ) is the ratio of H2 to the height variable section (H2 / (Rr c )), the ratio of the height variable section is preferably 1% to 56%, similar to the first electrode.

[0240] When the ratio of the height-variable section of the plain portion 43a' to the segment 61 satisfies the above numerical range, the ratio of the relative radial position where the number of laminated layers of the plain portion is 10 or more can be at least 30% of the radial length R2 of the wound turn including the segment 61.

[0241] In the winding structure of the second electrode 40′,

number

number

number

[0242] Preferably, in the winding structure of the first electrode 40, the uncoated portion 43a bent toward the core is divided into a plurality of segments 61, and at least one of the height in the winding axial direction and the width in the winding direction of the plurality of segments 61 may increase gradually or in steps from the core side toward the outer periphery, individually or in groups.

[0243] 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 may increase gradually or in steps from the core side toward the outer periphery, individually or in groups.

[0244] Preferably, when the folded portions of the plain portions 43a, 43a' are divided into a plurality of segments 61, each of the segments 61 may satisfy at least one of the following conditions: a width of 1 mm to 11 mm in the winding direction (D1 in FIG. 5), a height of 2 mm to 10 mm in the winding axial direction (D2 in FIG. 5), and a spacing pitch D3 of 0.05 mm to 1 mm in the winding direction.

[0245] Preferably, a predetermined gap may be provided between the bottom of the cutting groove of the divided piece 61 (D4 in FIG. 5) and the active material layer 42. Preferably, the gap may be 0.2 mm to 4 mm.

[0246] Referring to FIG. 4, when the folded portions of the plain portions 43a, 43a' are divided into a plurality of division segments 61, the division segments 61 form a plurality of division segment groups from the core side toward the outer periphery, and the division segments belonging to the same division segment group may have at least one of the same width in the winding direction, height in the winding axial direction, and spacing pitch in the winding direction.

[0247] Preferably, at least some of the plurality of segment groups may be arranged in the same winding turn of the electrode assembly 80. As an example, the segment included in each group may constitute at least one winding turn in the winding structure of the electrode assembly 80. As another example, the segment included in each group may constitute at least two winding turns in the winding structure of the electrode assembly 80.

[0248] FIG. 9a is a partial cross-sectional view showing an electrode assembly with a radius of 22 mm included in a cylindrical battery of form factor 4680, in which the uncoated portions 43a of the first electrode 40, which are divided into a plurality of segments 61, are bent from the outer periphery toward the core to form a folded surface region F, and in part of the folded surface region F, 10 or more uncoated portions 43a are overlapped along the radial direction, resulting in an area with an increased number of layers and an area with a uniform number of layers appearing along the radial direction of the electrode assembly 80.

[0249] 9a, the number of layers of the uncoated portions 43a in the folded surface region F gradually increases from the outer periphery of the electrode assembly 80 toward the core, reaches a maximum value, and then decreases by about one or two layers near the core after maintaining the maximum value for a predetermined radius section. The radius section near the core is called the layer number decreasing section.

[0250] Hereinafter, a radial section in which the number of layers in the uncoated portion 43a gradually increases from the outer periphery of the electrode assembly 80 toward the core to a maximum value is defined as an increasing layer number section, and a section in which the number of layers in the uncoated portion 43a is maintained at the maximum value and the remaining section near the core are collectively defined as a uniform layer number section. Since the uniform layer number section includes the section in which the number of layers in the uncoated portion 43a is maintained at the maximum value, the folded surface region F is flatter than other parts, and therefore corresponds to an optimal welding region.

[0251] 5, uncoated portion 43a is divided into trapezoidal sections, and only the upper portion of uncoated portion 43a is shown relative to bottom 63a of cut groove 63. The portion of uncoated portion 43a corresponding to the cross section of cut groove 63 is not shown.

[0252] The points at which the divided pieces 61 are actually folded are not exactly the same, but are spaced a predetermined distance from the bottom end of the cutting groove 63. Since resistance to folding occurs as the number of overlaps of the uncoated portion 43a increases toward the core, it is desirable to fold the divided pieces 61 at points spaced a predetermined distance from the bottom end of the cutting groove 63. The distance is 2 mm or less, and preferably 1 mm or less. The existence of a distance allows the divided pieces 61 to be folded more smoothly in the radial direction.

[0253] The folded surface region F is formed when segments 61 located on different winding turns overlap in the radial direction of the electrode assembly 80. In the embodiment shown in FIG. 9a, the segments 61 do not overlap in the circumferential direction. That is, as shown in FIG. 6(a), gaps exist between the sides of the segments 61. The condition for the existence of gaps can be satisfied by adjusting the width, height, spacing pitch, and lower interior angle of the segments. The folded surface region F when the segments overlap in the circumferential direction will be described later with reference to FIG. 9b.

[0254] In this embodiment, the radius r of the core of the electrode assembly 80 cThe height of the segment starts from 3 mm. No segment exists in the uncoated portion 43a from 4 mm to 7 mm based on the radius of the electrode assembly. In other words, out of the total radius of the electrode assembly of 22 mm, segment exists in the section of radius 7 mm to 22 mm, and the width of the radius section where segment 61 exists is 15 mm. If the radius r of the core c If a maximum of 10% of the base is blocked by the segment, the point where the segment placement begins can be moved toward the core.

[0255] In the wound structure, a segment having a height of 3 mm is placed from the winding turn at a radius of approximately 7 mm. The height of the segment increases by 1 mm per 1 mm increase in radius from the 7 mm radius of the wound structure toward the outer periphery. The period at which the height of the segment increases can be changed within a range of 0.2 mm to 1.2 mm per unit radius (1 mm).

[0256] Figure 9a (a) shows the case where the maximum height of the segment is 8 mm. In this case, the segment is positioned from the point where the radius of the electrode assembly is 7 mm from the center of the core. Therefore, when a segment with a height of 3 mm is bent toward the core, it will not block the core with a radius of 4 mm. The height of the segment increases in five steps from 3 mm to 8 mm as the radius increases from 7 mm to 12 mm. Also, the height of the segment is maintained at 8 mm from the radius of 12 mm to 22 mm. In this embodiment, the height-variable section of the segment is from the radius of 7 mm to 12 mm, and the ratio of the height-variable section is 28% (5 / 18, rounded to the nearest decimal place, same below).

[0257] Figure 9a (b) shows the case where the maximum height of the segment is 7 mm. In this case, the segment is positioned from the point where the radius of the electrode assembly is 7 mm from the center of the core. As a result, when a segment with a height of 3 mm is bent toward the core, it will not block the core with a radius of 4 mm. The height of the segment increases in four steps from 3 mm to 7 mm as the radius increases from 7 mm to 11 mm. Also, the height of the segment is maintained at 7 mm from the radius of 11 mm to 22 mm. In this embodiment, the height-variable section of the segment is from the radius of 7 mm to 11 mm, and the ratio of the height-variable section is 22% (4 / 18).

[0258] (c) of Figure 9a shows an example where the maximum height of the segment is 6 mm. In this case, the segment is positioned from the point where the radius of the electrode assembly is 7 mm from the center of the core. Therefore, when a segment with a height of 3 mm is bent toward the core, it will not block the core with a radius of 4 mm. The height of the segment increases in three steps from 3 mm to 6 mm as the radius increases from 7 mm to 10 mm. Furthermore, the height of the segment is maintained at 6 mm from the radius of 10 mm to 22 mm. In this embodiment, the height-variable section of the segment is from the radius of 7 mm to 10 mm, and the ratio of the height-variable section is 17% (3 / 18).

[0259] In the embodiment shown in Figures 9a(a), (b), and (c), the variable height section of the segment begins at a radius of 7 mm, and the ratio of the variable height section is 17% to 28%. This ratio range falls within the above-mentioned desirable range of 1% to 56%.

[0260] 9a, the number of layers of the uncoated portion 43a increases sequentially from the outer periphery toward the core, and even if the minimum length of the segment is the same at 3 mm, as the maximum length of the segment increases to 6 mm, 7 mm, and 8 mm, the maximum number of layers increases to 12, 15, and 18. In addition, the thickness of the folded surface region F increases proportionally to the number of layers.

[0261] For example, when the maximum height of the segment is 8 mm, the number of layers in the uncoated portion 43a increases to 18 in a section with a radius of 7 mm from the outer peripheral surface of the electrode assembly 80 toward the core, and then remains uniform at 18 layers in a section with a radius of 8 mm toward the core from the radius where the increase in the number of layers stops. In this example, the uniform layer count section has at least 16 layers and a radial width of 8 mm. The width of the uniform layer count section is 53% (8 / 15, rounded to the nearest decimal place, same below) of the radial length (15 mm) of the winding turn including the segment.

[0262] As another example, when the maximum height of the segment is 7 mm, the number of layers in the uncoated portion 43a increases to 15 in a 6 mm radius section from the outer peripheral surface of the electrode assembly 80 toward the core, and then remains uniform at 15 layers in a 9 mm radius section toward the core from the radius point where the increase in the number of layers stops. Therefore, the radial width of the uniform layer number section is 9 mm, and the number of layers in the uniform layer number section is at least 13. The width of the uniform layer number section is 60% (9 / 15) of the radial length (15 mm) of the winding turn including the segment.

[0263] As another example, when the maximum height of the segment is 5 mm, the number of layers in the uncoated portion 43a increases to 12 in a 5 mm radius section from the outer peripheral surface of the electrode assembly 80 toward the core, and then remains uniform at 12 layers in a 10 mm radius section toward the core from the radius point where the increase in the number of layers stops. Therefore, the radial width of the uniform layer number section is 10 mm, and the number of layers in the uniform layer number section is at least 11. The width of the uniform layer number section is 67% (10 / 15) of the radial length (15 mm) of the winding turn including the segment.

[0264] According to the embodiment shown in Figure 9a, when the minimum length of the divided segments is 3 mm and the maximum length of the divided segments is 6 mm, 7 mm, and 8 mm, the length of the stack number increasing section where the number of layers gradually increases increases to 5 mm, 6 mm, and 7 mm, respectively, and it can be confirmed that the ratio of the stack number uniform section where the number of layers in the plain portion 43a is 10 or more is 53% to 67%.

[0265] Meanwhile, the thickness of the folded surface region F increases in proportion to the number of layers of the uncoated portion 43a. The number of layers of the uncoated portion 43a can be as low as 10 depending on the minimum and maximum heights of the segment sections in the height-variable section, so the number of layers of the uncoated portion 43a is 10 to 18. For example, when the uncoated portion 43a is made of aluminum and has a thickness of 10 μm to 25 μm, the thickness of the folded surface region F can be 100 μm to 450 μm. For another example, when the uncoated portion 43a is made of copper and has a thickness of 5 μm to 20 μm, the thickness of the folded surface region F can be 50 μm to 360 μm. When the thickness of the folded surface region F satisfies the above numerical range, the folded surface region F can sufficiently absorb the laser energy when a current collector is welded to the folded surface region F using a laser. As a result, a weld bead is formed in the folded surface region F with a sufficient volume, increasing the weld strength. In addition, it is possible to prevent the separation film and the like located under the folded surface region F from being damaged by the laser drilling of the welding portion.

[0266] Preferably, the current collector may be welded to the folded surface region F. The welded region of the current collector may at least partially overlap with the uniform lamination number section in the radial direction.

[0267] Preferably, 50% to 100% of the welding area of ​​the current collector overlaps with the uniform lamination number section in the radial direction of the electrode assembly. The greater the overlap ratio of the welding area, the more desirable it is in terms of improving the welding strength and increasing the weld bead volume. The remaining area of ​​the welding area of ​​the current collector that does not overlap with the uniform lamination number section may overlap with the increased lamination number section.

[0268] Meanwhile, as described with reference to Figure 6, when the divisional segments 61 of the uncoated portion 43a are folded to form the folded surface area F, if the lower interior angles of the divisional segments included in each divisional segment group satisfy the condition of Equation 1, the sides of adjacent divisional segments 61 located in the same winding turn may intersect and overlap each other in the circumferential direction. In this case, the number of stacked uncoated portions 43a in the radial direction of the electrode assembly is further increased.

[0269] FIG. 9b is a cross-sectional view of the folded surface region F exemplarily showing an increased lamination number section and a uniform lamination number section when the segment pieces overlap in the circumferential direction.

[0270] Referring to Figure 9b, the number of overlaps of the uncoated portion 43a increases sequentially from the outer periphery toward the core. The variable height section of the segment starts at a radius of 7 mm, as in the embodiment of Figure 9a. The segment height starts at 3 mm and increases by 1 mm for each 1 mm increase in radius. As the maximum segment height increases to 6 mm, 7 mm, 8 mm, 9 mm, and 10 mm, the number of layers at the radial position where the uniform layer number section begins increases to 18, 22, 26, 30, and 34. Under the same conditions where the maximum segment height is 6 mm, 7 mm, and 8 mm, the number of layers is 6 to 8 more than in the embodiment of Figure 9a. This is because the segment segments overlap in the circumferential direction.

[0271] Specifically, when the maximum height of the segment is 10 mm, the number of laminations in the uncoated portion 43a increases to 34 in a 9 mm radius section (the lamination number increasing section) from the outer peripheral surface of the electrode assembly 80 toward the core. It remains at 34 in a 6 mm radius section from the radius point where the increase in the lamination number stops toward the core, and then further increases to 39 near the core. The further increase in the number of laminations near the core occurs because the overlap of the segment in the circumferential direction increases toward the core. The radius section near the core where the number of laminations further increases can be defined as the lamination number additional increase section. In this example, the lamination number uniform section has at least 34 laminations and a radial width of 6 mm. The lamination number uniform section begins at a 7 mm radius and is 40% (6 / 15, rounded to the nearest decimal place; the same applies below) of the radial length (15 mm) of the winding turn including the segment.

[0272] As another example, when the maximum height of the segment is 9 mm, the number of laminations in the uncoated portion 43a increases to 30 in an 8 mm radius section from the outer peripheral surface of the electrode assembly 80 toward the core, remains at 30 in an 7 mm radius section toward the core from the radius point where the increase in the number of laminations stops, and then increases further to 36 near the core. Therefore, the uniform lamination number section has a radial width of 7 mm and a number of laminations of at least 30. The uniform lamination number section begins at a 7 mm radius and is 47% (7 / 15) of the radial length (15 mm) of the winding turn including the segment.

[0273] As another example, when the maximum height of the segment is 8 mm, the number of laminations in the uncoated portion 43a increases to 26 in a 7 mm radius section from the outer peripheral surface of the electrode assembly 80 toward the core, maintains 26 in a 8 mm radius section from the radius point where the increase in the number of laminations stops toward the core, and then increases further to 28 near the core. Therefore, the uniform lamination number section has a radial width of 8 mm and a number of laminations of at least 26. The uniform lamination number section begins at a 7 mm radius and is 53% (8 / 15) of the radial length (15 mm) of the winding turn including the segment.

[0274] As another example, when the maximum height of the segment is 7 mm, the number of overlaps of the uncoated portion 43a increases to 22 in a 6 mm radius section from the outer peripheral surface of the electrode assembly 80 toward the core, remains at 22 in a 9 mm radius section toward the core from the radius point where the increase in the number of overlaps stops, and then increases further to 23 near the core. Therefore, the uniform lamination number section has a radial width of 9 mm and a number of laminations of at least 22. The uniform lamination number section begins at a 7 mm radius and is a section that corresponds to 60% (9 / 15) of the radial length (15 mm) of the winding turn including the segment.

[0275] As another example, when the maximum height of the segment is 6 mm, the number of overlaps of the uncoated portion 43a increases to 18 in a 5 mm radius section from the outer peripheral surface of the electrode assembly 80 toward the core, remains at 18 in a 10 mm radius section toward the core from the radius point where the increase in the number of overlaps stops, and then increases further to 20 near the core. Therefore, the uniform lamination number section has a radial width of 10 mm and a number of at least 18 laminations. The uniform lamination number section begins at a 7 mm radius and is a section that corresponds to 67% (10 / 15) of the radial length (15 mm) of the winding turn including the segment.

[0276] According to the embodiment shown in Figure 9b, when the minimum value of the segment height is 3mm and the maximum value of the segment height is 6mm, 7mm, 8mm, 9mm, and 10mm, the length of the stack number increasing section where the number of layers gradually increases increases to 5mm, 6mm, 7mm, 8mm, and 9mm. It can also be seen that the ratio of the uniform stack number section where the number of layers is 10 or more is 40% to 67%.

[0277] Meanwhile, in the embodiment of FIG. 9b, the thickness of the folded surface region F increases in proportion to the number of layers of the uncoated portion 43a. The number of layers of the uncoated portion 43a is 18 to 39. For example, when the uncoated portion 43a is made of aluminum and has a thickness of 10 μm to 25 μm, the thickness of the folded surface region F may be 180 μm to 975 μm. For another example, when the uncoated portion 43a is made of copper and has a thickness of 5 μm to 20 μm, the thickness of the folded surface region F may be 90 μm to 780 μm. When the thickness of the folded surface region F satisfies the above numerical range, the folded surface region F can sufficiently absorb the laser energy when a current collector is welded to the folded surface region F using a laser. As a result, a weld bead is formed in the folded surface region F with sufficient volume, increasing the weld strength. In addition, the welded portion can be prevented from being perforated by the laser, which can damage the separator film and other components located below the folded surface region F.

[0278] Preferably, at least a portion of the welding region of the current collector may overlap with the uniform lamination number section in the radial direction. Preferably, 50% to 100% of the welding region of the current collector may overlap with the uniform lamination number section in the radial direction of the electrode assembly 80. The greater the overlap ratio of the welding region, the better in terms of weld strength. The region of the welding region of the current collector that does not overlap with the uniform lamination number section may overlap with the increasing lamination number section.

[0279] In the embodiment shown in FIGS. 9a and 9b, the uniform lamination number section of the uncoated portion 43a is formed by dividing the radius R of the electrode assembly by the radius r c It will be obvious to those skilled in the art that the minimum and maximum heights of the segment in the height variable section of the segment and the width of increase in height of the segment in the radial direction of the electrode assembly can be increased or decreased.

[0280] The ratio of the uniform number of layers is the core r c The ratio of the uniform number of layers section increases as the width of the height variable section becomes narrower when the minimum height of the sub-segment is the same. The ratio of the uniform number of layers section increases as the width of the height variable section becomes narrower when the maximum height of the sub-segment is the same.

[0281] As an example, the diameter R of the electrode assembly is 22 mm, and the radius r of the core is c When the radius of the section is 2 mm and the section height varies from 7 mm to 10 mm with a radius of 9 mm to 12 mm, the ratio of the uniform number of layers can be reduced to the 30% level.

[0282] As another example, if the diameter R of the electrode assembly is 22 mm and the radius r of the core is c When the radius of the section is 2 mm and the section height varies from 3 mm to 4 mm in the section with variable section height, the ratio of the uniform number of layers can increase up to 85%.

[0283] Therefore, the radial length of the uniform lamination number section may be 30% or more, and preferably 30% to 85%, of the radial length of the winding turn including the segment.

[0284] Meanwhile, as described above with reference to Figures 9a and 9b, when the maximum height of the segment in the uniform segment height section is 6mm to 10mm, the number of layers of the uncoated portion 43a in the uniform layer number section can be adjusted to a range of 10 to 39 by changing the minimum height of the segment and the radial increase in height of the segment. The uniform layer number section of the folded surface region F includes a section formed by folding the segment included in the uniform height section. The thickness of the folded 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 has a thickness of 10µm to 25µm, the layer thickness of the uncoated portion in the folded surface region F is 100µm (0.1mm) to 975µm (0.975mm). In this case, in the portion of the folded surface region F formed by bending a 6mm to 10mm high segment included in the uniform height section, the ratio of the laminate thickness of the uncoated portion of the folded surface region F to the height of the segment is 1.0% (0.1mm / 10mm) to 16.3% (0.975mm / 6mm). As another example, when the uncoated portion 43a is made of copper and has a thickness of 5µm to 20µm, the laminate thickness of the uncoated portion of the folded surface region F is 50µm (0.05mm) to 780µm (0.780mm). In this case, in the portion of the folded surface region F formed by bending a 6mm to 10mm high segment included in the uniform height section, the ratio of the laminate thickness of the uncoated portion of the folded surface region F to the height of the segment is 0.5% (0.05mm / 10mm) to 13.0% (0.780mm / 6mm). When the ratio of the thickness of the folded surface region F to the height of the segment included in the uniform height section satisfies the above numerical range, a desired welding strength can be achieved when welding a current collector to the corresponding folded surface region F.

[0285] The various electrode assembly structures according to the embodiments (variations) of the present invention can be applied not only to jelly-roll type cylindrical batteries but also to any batteries known in the art.

[0286] Desirably, the cylindrical battery may be, for example, a cylindrical battery having a form factor ratio (defined as the diameter of a cylindrical battery divided by its height, i.e., the ratio of height (H) to diameter (Φ)) greater than about 0.4.

[0287] Here, the form factor refers to a value indicating the diameter and height of a cylindrical battery. Form factors of a cylindrical battery according to an embodiment of the present invention may be, for example, 46110, 4875, 48110, 4880, 4680, etc. In the form factor number, the first two digits indicate the diameter of the battery, and the remaining digits indicate the height of the battery.

[0288] When an electrode assembly having a tabless structure is applied to a cylindrical battery with a form factor ratio exceeding 0.4, the uncoated portion is susceptible to tearing due to the large radial stress applied when the uncoated portion is bent. Furthermore, when welding a current collector to the bent surface area of ​​the uncoated portion, the number of layers of the uncoated portion must be increased to ensure sufficient welding strength and reduce resistance. These requirements can be met by the electrode plate and electrode assembly according to an embodiment (variant) of the present invention.

[0289] A battery according to one embodiment of the present invention may be a cylindrical battery that is roughly cylindrical, with a diameter of about 46 mm, a height of about 110 mm, and a form factor ratio of 0.418.

[0290] Another embodiment of the battery may be a cylindrical battery that is generally cylindrical, with a diameter of about 48 mm, a height of about 75 mm, and a form factor ratio of 0.640.

[0291] In yet another embodiment, the battery may be a cylindrical battery that is generally cylindrical, having a diameter of about 48 mm, a height of about 110 mm, and a form factor ratio of 0.436.

[0292] In yet another embodiment, the battery may be a cylindrical battery that is generally cylindrical, having a diameter of about 48 mm, a height of about 80 mm, and a form factor ratio of 0.600.

[0293] In yet another embodiment, the battery may be a cylindrical battery that is generally cylindrical, having a diameter of about 46 mm, a height of about 80 mm, and a form factor ratio of 0.575.

[0294] Conventionally, batteries with a form factor ratio of approximately 0.4 or less have been used. For example, 1865 batteries and 2170 batteries have been used. 1865 batteries have a diameter of approximately 18 mm and a height of approximately 65 mm, resulting in a form factor ratio of 0.277. 2170 batteries have a diameter of approximately 21 mm and a height of approximately 70 mm, resulting in a form factor ratio of 0.300.

[0295] Hereinafter, a cylindrical battery according to an embodiment of the present invention will be described in detail.

[0296] FIG. 10 is a cross-sectional view of a cylindrical battery 190 according to an embodiment of the present invention taken along the Y-axis direction.

[0297] Referring to FIG. 10, a cylindrical battery 190 according to one embodiment of the present invention includes an electrode assembly 110 including a first electrode, a separator, and a second electrode, a battery housing 142 that houses the electrode assembly 110, and a seal 143 that seals the open end of the battery housing 142.

[0298] The battery housing 142 is a cylindrical container with an opening at the top. The battery housing 142 is made of a conductive metal material such as aluminum or steel. The battery housing 142 accommodates the electrode assembly 110 in the inner space through the opening at the top, along with the electrolyte.

[0299] The electrolyte is A + B -where A + Li + , Na + , K. + or a combination thereof. - is 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 - The anion comprises one or more anions selected from the group consisting of:

[0300] The electrolyte may be dissolved in an organic solvent such as propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), γ-butyrolactone, or a mixture thereof.

[0301] The electrode assembly 110 may have, without limitation, a jelly roll structure or a structure known in the art. As shown in FIG. 2, the electrode assembly 110 may be manufactured by sequentially stacking a lower separator, a first electrode, an upper separator, and a second electrode at least once, and winding the stack around a winding center C.

[0302] The first electrode and the second electrode have opposite polarities. That is, if one has a positive polarity, the other has a negative polarity. At least one of the first electrode and the second electrode may have an electrode structure according to the above-described embodiment (variant). The other of the first electrode and the second electrode may have a conventional electrode structure or an electrode structure according to the embodiment (variant).

[0303] A first uncoated portion 146a of the first electrode and an uncoated portion 146b of the second electrode protrude from the top and bottom of the electrode assembly 110, respectively.

[0304] The sealing body 143 may include a cap 143a, a first gasket 143b having insulating properties and providing airtightness between the cap 143a and the battery housing 142, and a connecting plate 143c electrically and mechanically coupled to the cap 143a.

[0305] The cap 143a is a component made of a conductive metal material and covers the upper opening of the battery housing 142. The cap 143a is electrically connected to the first uncoated portion 146a of the first electrode and is electrically insulated from the battery housing 142 via the first gasket 143b. Therefore, the cap 143a can function as the first electrode terminal of the cylindrical battery 140.

[0306] The cap 143a is placed on a beading portion 147 formed on the battery housing 142 and fixed by a crimping portion 148. A first gasket 143b may be interposed between the cap 143a and the crimping portion 148 to ensure airtightness of the battery housing 142 and to provide electrical insulation between the battery housing 142 and the cap 143a. The cap 143a may have a protrusion 143d formed to protrude upward from the center thereof.

[0307] The battery housing 142 is electrically connected to the uncoated portion 146b of the second electrode. Therefore, the battery housing 142 has the same polarity as the second electrode. If the second electrode has a negative polarity, the battery housing 142 also has a negative polarity.

[0308] The battery housing 142 has a beading portion 147 and a crimping portion 148 at its upper end. The beading portion 147 is formed by pressing in around the outer periphery of the battery housing 142. The beading portion 147 prevents the electrode assembly 110 housed inside the battery housing 142 from slipping out of the upper opening of the battery housing 142, and can also function as a support portion on which the sealing body 143 is placed.

[0309] The crimping portion 148 is formed on the upper portion of the beading portion 147. The crimping portion 148 is extended and bent to enclose the outer circumferential surface of the cap 143a disposed on the beading portion 147 and a part of the upper surface of the cap 143a.

[0310] The cylindrical battery 140 may further include a first current collector 144 and / or a second current collector 145 and / or an insulator 146 .

[0311] The first current collector 144 has a plate shape and is coupled to the upper part of the electrode assembly 110. The first current collector 144 is made of a conductive metal material such as aluminum, copper, or nickel, and is electrically connected to a bent surface region F1 formed by bending the first uncoated portion 146a of the first electrode.

[0312] A lead 149 may be connected to the first current collector 144. The lead 149 may extend above the electrode assembly 110 and be connected to the connection plate 143c, or may be directly connected to the lower surface of the cap 143a. The connection of the lead 149 to other components may be performed by welding.

[0313] Preferably, the first current collector 144 may be integrally formed with the lead 149. In this case, the lead 149 may have a long plate shape extending outward from the center of the first current collector 144.

[0314] The folded surface region F1 of the first uncoated portion 146a may be bonded to the first current collector 144 by, for example, laser welding. Laser welding may be performed by partially melting the base material of the current collector. Laser welding may be replaced by resistance welding, ultrasonic welding, etc.

[0315] Preferably, the first uncoated portion 146a is divided into a plurality of segments, and the folded surface region F1 is formed by folding the plurality of segments toward the core C. The radial length of the folded surface region F1, where the number of layers of the first uncoated portion 146a is 10 or more, may be 30% or more, more preferably 30% to 85%, of the radial length of the wound turn including the segments.

[0316] The welding area between the folded surface region F1 of the first uncoated portion 146a and the first current collector 144 may overlap with the uniform lamination number section W1 of the folded surface region F1 by at least 50%, and the higher the overlap ratio, the more preferable.

[0317] When the folded surface area F1 of the first non-coating portion 146a and the first current collector 144 are welded by a laser, the welding strength is preferably 2 kgf / cm 2 More preferably, 4kgf / cm 2 The upper limit of the welding strength can be determined by the specifications of the laser welding equipment. For example, the welding strength is 8 kgf / cm 2 or less than 6kgf / cm 2 The laser output power required to achieve the required welding strength varies depending on the laser device. For example, the laser output power may be 250W to 320W. For another example, the laser output power may be appropriately adjusted within a range of 40% to 100% of the maximum output power specification of the laser welding device.

[0318] When the weld strength satisfies the above numerical range, the physical properties of the weld interface do not deteriorate even when the electrode assembly 110 is subjected to severe vibrations in the winding axial direction and / or radial direction, and the resistance of the weld interface can also be reduced due to the sufficient volume of the weld beads.

[0319] A plate-shaped second current collector 145 may be coupled to the lower surface of the electrode assembly 110. One surface of the second current collector 145 may be coupled by welding to a bent surface region F2 formed by bending the uncoated portion 146b of the second electrode, and the other surface may be coupled to the inner bottom surface of the battery housing 142 by welding.

[0320] Preferably, the uncoated portion 146b is divided into a plurality of segments, and the folded surface region F2 is formed by folding the plurality of segments toward the core C. In the folded surface region F2, the radial length of the uncoated portion 146b, where the number of layers is 10 or more, may be 30% or more, more preferably 30% to 85%, of the radial length of the wound turn including the segments.

[0321] The bonding structure between the second current collector 145 and the uncoated portion 146b of the second electrode may be substantially the same as the bonding structure between the first current collector 144 and the first uncoated portion 146a of the first electrode.

[0322] The welded area between the folded surface area F2 of the non-coating portion 146b and the second current collector 145 may overlap with the uniform lamination number section W2 by at least 50%, and the higher the overlap ratio, the more preferable.

[0323] When the folded surface area F2 of the non-coating portion 146b and the second current collector 145 are welded by a laser, the welding strength is preferably 2 kgf / cm 2 More preferably, 4kgf / cm 2 The upper limit of the welding strength can be determined by the specifications of the laser welding equipment. For example, the welding strength is 8 kgf / cm 2 or less than 6kgf / cm 2 The laser output power required to achieve the required welding strength varies depending on the laser device. For example, the laser output power may be 250W to 320W. For another example, the laser output power may be appropriately adjusted within a range of 40% to 100% of the maximum output power specification of the laser welding device.

[0324] When the weld strength satisfies the above numerical range, the physical properties of the weld interface do not deteriorate even when the electrode assembly 110 is subjected to severe vibrations in the winding axial direction and / or radial direction, and the resistance of the weld interface can also be reduced due to the sufficient volume of the weld beads.

[0325] The insulator 146 can cover the first current collector 144. By covering the first current collector 144 on the upper surface of the first current collector 144, the insulator 146 can prevent direct contact between the first current collector 144 and the inner circumferential surface of the battery housing 142.

[0326] The insulator 146 has a lead hole 151 through which the lead 149 extending upward from the first current collector 144 is drawn out. The lead 149 is drawn out upward through the lead hole 151 and coupled to the lower surface of the connection plate 143c or the lower surface of the cap 143a.

[0327] The peripheral region of the insulator 146 may be interposed between the first current collector 144 and the beading portion 147 to fix the combination of the electrode assembly 110 and the first current collector 144. This limits the movement of the combination of the electrode assembly 110 and the first current collector 144 in the height direction of the cylindrical battery 140, thereby improving the assembly stability of the cylindrical battery 140.

[0328] The insulator 146 may be made of an insulating polymer resin. As an example, the insulator 146 may be made of polyethylene, polypropylene, polyimide, or polybutylene terephthalate.

[0329] The battery housing 142 may further include a venting portion 152 formed on its bottom surface. The venting portion 152 corresponds to a region on the bottom surface of the battery housing 142 that is thinner than the surrounding region. The venting portion 152 is structurally weaker than the surrounding region. Therefore, if an abnormality occurs in the cylindrical battery 190 and the internal pressure increases above a certain level, the venting portion 152 may burst, causing gas generated inside the battery housing 142 to be released to the outside.

[0330] The vents 152 may be formed continuously or discontinuously in a circular pattern on the underside of the battery housing 142. Alternatively, the vents 152 may be formed in a linear pattern or other patterns.

[0331] FIG. 11 is a cross-sectional view of a cylindrical battery 200 according to another embodiment of the present invention, taken along the Y-axis direction.

[0332] Referring to FIG. 11, a cylindrical battery 200 differs from the cylindrical battery 190 shown in FIG. 10 in that the structure of the electrode assembly is substantially the same, but other structures except for the electrode assembly have been changed.

[0333] Specifically, the cylindrical battery 200 includes a battery housing 171 through which a terminal 172 is inserted. The terminal 172 is attached to the closed surface (top surface in the drawing) of the battery housing 171. The terminal 172 is riveted into a through-hole in the battery housing 171 with an insulating second gasket 173 interposed therebetween. The terminal 172 is exposed to the outside in the direction opposite to the direction of gravity.

[0334] The terminal 172 includes a terminal exposure portion 172a and a terminal insertion portion 172b. The terminal exposure portion 172a is exposed to the outside of the closed surface of the battery housing 171. The terminal exposure portion 172a may be located approximately at the center of the closed surface of the battery housing 171. The maximum diameter of the terminal exposure portion 172a may be larger than the maximum diameter of the through-hole formed in the battery housing 171. The terminal insertion portion 172b may penetrate approximately the center of the closed surface of the battery housing 171 to be electrically connected to the first uncoated portion 146a of the first electrode. The terminal insertion portion 172b may be rivet-connected to the inner surface of the battery housing 171. That is, the bottom edge of the terminal insertion portion 172b may be bent toward the inner surface of the battery housing 171. The maximum diameter of the bottom of the terminal insertion portion 172b may be larger than the maximum diameter of the through-hole in the battery housing 171.

[0335] The lower end surface of the terminal insertion portion 172b is substantially flat and may be welded to the center of the first current collector 144 connected to the first uncoated portion 146a of the first electrode. An insulator 174 made of an insulating material may be interposed between the first current collector 144 and the inner surface of the battery housing 171. The insulator 174 covers the upper portion of the first current collector 144 and the upper peripheral edge of the electrode assembly 110. This prevents the first uncoated portion 146a exposed on the outer periphery of the electrode assembly 110 from coming into contact with the inner surface of the battery housing 171, which has the opposite polarity, and causing a short circuit.

[0336] The insulator 174 contacts the inner surface of the closed portion of the battery housing 171 and the upper surface of the first current collector 144. Therefore, the insulator 174 has a thickness that corresponds to the separation distance between the inner surface of the closed portion of the battery housing 171 and the upper surface of the first current collector 144 or a thickness that is slightly larger than the separation distance.

[0337] Preferably, the first current collector 144 may be laser-welded to the folded surface region F1 of the first uncoated portion 146a in a region including a uniform layer number section where the number of layers of the first uncoated portion 146a is 10 or more in the folded surface region F1 of the first uncoated portion 146a.

[0338] The radial length of the uniform lamination number section in which the number of laminations of the first non-coating portion 146a is 10 or more may be 30% or more, more preferably 30% to 85%, of the radial length of the wound turn including the segment.

[0339] The welding area between the folded surface area F1 of the first non-coating portion 146a and the first current collector 144 may overlap with the uniform lamination number section W1 by at least 50%, and the higher the overlap ratio, the more preferable.

[0340] When the folded surface area F1 of the first non-coating portion 146a and the first current collector 144 are welded by a laser, the welding strength is preferably 2 kgf / cm 2 More preferably, 4kgf / cm 2 The upper limit of the welding strength can be determined by the specifications of the laser welding equipment. For example, the welding strength is 8 kgf / cm 2 or less than 6kgf / cm 2 The laser output power required to achieve the required welding strength varies depending on the laser device. For example, the laser output power may be 250W to 320W. For another example, the laser output power may be appropriately adjusted within a range of 40% to 100% of the maximum output power specification of the laser welding device.

[0341] When the weld strength satisfies the above numerical range, the physical properties of the weld interface do not deteriorate even when the electrode assembly 110 is subjected to severe vibrations in the winding axial direction and / or radial direction, and the resistance of the weld interface can also be reduced due to the sufficient volume of the weld beads.

[0342] The second gasket 173 is interposed between the battery housing 171 and the terminal 172 to prevent electrical contact between the battery housing 171 and the terminal 172, which have opposite polarities. This allows the upper surface of the battery housing 171, which has a substantially flat shape, to function as the second electrode terminal of the cylindrical battery 200.

[0343] The second gasket 173 includes a gasket exposing portion 173a and a gasket inserting portion 173b. The gasket exposing portion 173a is interposed between the terminal exposing portion 172a of the terminal 172 and the battery housing 171. The gasket inserting portion 173b is interposed between the terminal inserting portion 172b of the terminal 172 and the battery housing 171. The gasket inserting portion 173b may be deformed when the terminal inserting portion 172b is riveted, thereby adhering closely to the inner surface of the battery housing 171. The second gasket 173 may be made of, for example, an insulating polymer resin.

[0344] The gasket exposing portion 173a of the second gasket 173 may extend to cover the outer peripheral surface of the terminal exposing portion 172a of the terminal 172. When the second gasket 173 covers the outer peripheral surface of the terminal 172, it is possible to prevent a short circuit from occurring during the process of connecting an electrical connection component, such as a bus bar, to the upper surface of the battery housing 171 and / or the terminal 172. Although not shown, the gasket exposing portion 173a may extend to cover not only the outer peripheral surface of the terminal exposing portion 172a but also a portion of the upper surface.

[0345] When the second gasket 173 is made of a polymer resin, the second gasket 173 can be joined to the battery housing 171 and the terminal 172 by heat sealing. In this case, the airtightness at the joining interface between the second gasket 173 and the terminal 172 and at the joining interface between the second gasket 173 and the battery housing 171 is strengthened. On the other hand, when the gasket exposed portion 173a of the second gasket 173 extends to the upper surface of the terminal exposed portion 172a, the terminal 172 may be joined integrally with the second gasket 173 by insert injection.

[0346] The remaining area 175 on the top surface of the battery housing 171 excluding the area occupied by the terminal 172 and the second gasket 173 corresponds to a second electrode terminal having a polarity opposite to that of the terminal 172 .

[0347] The second current collector 176 is coupled to the lower part of the electrode assembly 110. The second current collector 176 is made of a conductive metal material such as aluminum, steel, copper, or nickel, and is electrically connected to the uncoated portion 146b of the second electrode.

[0348] Preferably, the second current collector 176 is electrically connected to the battery housing 171. Therefore, the second current collector 176 may be fixed with at least a portion of its outer edge interposed between the inner surface of the battery housing 171 and the first gasket 178b.

[0349] As an example, at least a portion of the outer edge of the second current collector 176 may be fixed to the beading portion 180 by welding while being supported on the lower end surface of the beading portion 180 formed at the lower end of the battery housing 171. In a modified example, at least a portion of the outer edge of the second current collector 176 may be directly welded to the inner wall surface of the battery housing 171.

[0350] Preferably, the second current collector 176 and the folded surface region F2 of the non-coating portion 146b may be joined by welding, for example, laser welding, in a region of the folded surface region F2 of the non-coating portion 146b that includes a uniform layer count section where the number of layers of the non-coating portion 146b is 10 or more.

[0351] The radial length of the non-coating portion 146b in which the number of layers is 10 or more may be 30% or more, more preferably 30% to 85%, of the radial length of the wound turn including the segment.

[0352] The welding area between the folded surface area F2 of the non-coating portion 146b and the second current collector 176 may overlap with the uniform lamination number section W2 by at least 50%, and the higher the overlap ratio, the more preferable.

[0353] When the folded surface region F2 of the non-coating portion 146b and the second current collector 176 are welded by a laser, the welding strength is preferably 2 kgf / cm 2 More preferably, 4kgf / cm 2 It could be more than that.

[0354] When the weld strength satisfies the above numerical range, the physical properties of the weld interface do not deteriorate even when the electrode assembly 110 is subjected to severe vibrations in the winding axial direction and / or radial direction, and the resistance of the weld interface can also be reduced due to the sufficient volume of the weld beads.

[0355] The sealing body 178 that seals the lower open end of the battery housing 171 includes a cap 178a and a first gasket 178b. The first gasket 178b electrically separates the cap 178a from the battery housing 171. A crimping portion 181 secures the periphery of the cap 178a and the first gasket 178b together. The cap 178a is provided with a vent portion 179. The configuration of the vent portion 179 is substantially the same as that of the above-described embodiment (variant).

[0356] Preferably, cap 178a is made of a conductive metal material. However, cap 178a does not have electrical polarity because first gasket 178b is interposed between cap 178a and battery housing 171. Sealing body 178 seals the open end of the lower part of battery housing 171 and functions to release gas when the internal pressure of battery 200 exceeds a critical value.

[0357] Preferably, the terminal 172 electrically connected to the first uncoated portion 146a of the first electrode is used as the first electrode terminal. Furthermore, a portion 175 of the upper surface of the battery housing 171, excluding the terminal 172, electrically connected to the uncoated portion 146b of the second electrode via the second current collector 176 is used as the second electrode terminal having the opposite polarity to the first electrode terminal. When two electrode terminals are located on the upper portion of the cylindrical battery 200, electrical connection components such as bus bars can be disposed on only one side of the cylindrical battery 200. This simplifies the battery pack structure and improves energy density. Furthermore, the portion 175 used as the second electrode terminal has a substantially flat shape, ensuring a sufficient contact area for connecting electrical connection components such as bus bars. This allows the cylindrical battery 200 to reduce resistance at the contact points of the electrical connection components to a desired level.

[0358] In the present invention, even if the non-coating portions 146a and 146b are bent toward the core side, the core C of the electrode assembly 110 is not closed but can be opened upward.

[0359] That is, as shown in FIG. 4, the height of the uncoated portions of the first and second electrodes, particularly the height of the core-side uncoated portion A, is designed to be low, and a height-adjustable section of the dividing segment 61 is disposed adjacent to the core-side uncoated portion A. By adjusting the height of the dividing segment 61 closest to the core-side uncoated portion A, the core C of the electrode assembly 110 is not blocked even if the uncoated portion near the core of the electrode assembly 110 is bent.

[0360] If the core C is not blocked, the electrolyte injection process can be carried out without any problems, improving the efficiency of the electrolyte injection. In addition, by inserting a welding jig into the core C, the welding process between the current collector 145 and the bottom surface of the battery housing 142 or the welding process between the current collector 144 and the terminal 172 can be easily carried out.

[0361] When the plain portions 146a, 146b have a divided structure, if the width and / or height and / or spacing pitch of the divided pieces are adjusted to satisfy the numerical range of the above-mentioned embodiment, when the divided pieces are bent, the divided pieces overlap each other to an extent that sufficient welding strength can be ensured, and no open spaces (gaps) are formed on the folded surface areas F1, F2.

[0362] In the present invention, the welding areas of the first current collector 144 and the second current collector 176 are spaced apart by 4 mm or more in the radial direction based on the center of the core C of the electrode assembly 110, and may be spaced apart by a distance of 50% or less of the radius of the electrode assembly 110. The 4 mm separation distance was determined in consideration of the minimum radius of the core C (2 mm) and the minimum height of the segment 61 (2 mm). The distance of 50% or less of the radius of the electrode assembly 110 was set in consideration of ensuring a sufficient welding area.

[0363] In addition, the welding area of ​​the first current collector 144 and the welding area of ​​the second current collector 176 may extend in the radial direction of the electrode assembly from positions spaced apart by substantially the same distance from the center of the core C of the electrode assembly 110. In this case, it is preferable that the extension length of the welding area of ​​the first current collector is longer than the extension length of the welding area of ​​the second current collector.

[0364] Meanwhile, the first current collector 144 and the second current collector 176 may have a new structure as shown in FIGS.

[0365] FIG. 12 is a top view showing the structure of a first current collector 144 according to an embodiment of the present invention.

[0366] 12, the first current collector 144 may include a peripheral portion 144a, a first uncoated portion coupling portion 144b, and a terminal coupling portion 144c. The peripheral portion 144a is disposed on the upper portion of the electrode assembly 110. The peripheral portion 144a may have a generally rim shape with an empty space S formed therein. Although the drawings only show the peripheral portion 144a in a generally circular rim shape, the present invention is not limited thereto. The peripheral portion 144a may have a generally square rim shape, a hexagonal rim shape, an octagonal rim shape, or other rim shapes, unlike those shown in the drawings.

[0367] The terminal coupling portion 144c may have a diameter equal to or larger than the diameter of the flat portion formed on the bottom surface of the terminal 172 to ensure a welding area for coupling with the flat portion formed on the bottom surface of the terminal 172.

[0368] The first uncoated portion coupling portion 144b extends inward from the peripheral portion 144a and is coupled to the first uncoated portion 146a. The terminal coupling portion 144c is spaced apart from the first uncoated portion coupling portion 144b and positioned inside the peripheral portion 144a. The terminal coupling portion 144c may be coupled to the terminal 172 by welding. The terminal coupling portion 144c may be positioned, for example, approximately at the center of the inner space surrounded by the peripheral portion 144a. The terminal coupling portion 144c may be provided at a position corresponding to a hole formed in the core C of the electrode assembly 110. The terminal coupling portion 144c may cover the hole formed in the core C of the electrode assembly 110 so that the hole is not exposed to the outside of the terminal coupling portion 144c. Therefore, the terminal coupling portion 144c may have a larger diameter or width than the hole formed in the core C of the electrode assembly 110.

[0369] The first uncoated portion coupling portion 144b and the terminal coupling portion 144c may be spaced apart and indirectly coupled via the peripheral portion 144a. In this manner, the first current collector 144 has a structure in which the first uncoated portion coupling portion 144b and the terminal coupling portion 144c are not directly coupled but are coupled via the peripheral portion 144a. This structure allows the cylindrical battery 200 to disperse shocks and / or vibrations applied to the coupling portion between the first uncoated portion coupling portion 144b and the first uncoated portion 146a and the coupling portion between the terminal coupling portion 144c and the terminal 172. While four first uncoated portion coupling portions 144b are illustrated in the drawings, the present invention is not limited thereto. The number of first uncoated portion coupling portions 144b may be determined in various ways, taking into consideration factors such as the difficulty of manufacturing due to the complexity of the shape, electrical resistance, and the internal space of the peripheral portion 144a in consideration of electrolyte impregnation.

[0370] The first current collector 144 may further include a bridge portion 144d extending inward from the peripheral portion 144a and connecting to the terminal coupling portion 144c. The bridge portion 144d may have a cross-sectional area smaller than that of the first non-coating portion coupling portion 144b and the peripheral portion 144a. For example, the bridge portion 144d may have a width and / or thickness smaller than that of the first non-coating portion coupling portion 144b. In this case, electrical resistance increases in the bridge portion 144d. As a result, when current flows through the bridge portion 144d, the relatively large resistance causes a portion of the bridge portion 144d to melt due to overcurrent heating, thereby irreversibly blocking the overcurrent. The cross-sectional area of ​​the bridge portion 144d may be adjusted to an appropriate level in consideration of this overcurrent blocking function.

[0371] The bridge portion 144d may include a tapered portion 144e whose width gradually narrows from the inner surface of the peripheral portion 144a toward the terminal coupling portion 144c. The tapered portion 144e improves the rigidity of the component at the connection portion between the bridge portion 144d and the peripheral portion 144a. The tapered portion 144e allows, for example, a transfer device and / or a worker to grip the tapered portion 144e during the manufacturing process of the cylindrical battery 200, thereby allowing the first current collector 144 and / or the combination of the first current collector 144 and the electrode assembly 110 to be easily and safely transported. That is, the tapered portion 144e can prevent product defects caused by gripping portions to be welded to other components, such as the first uncoated portion coupling portion 144b and the terminal coupling portion 144c.

[0372] The first non-coating portion joining portions 144b may be provided in plurality. The first non-coating portion joining portions 144b may be disposed at equal intervals along the extension direction of the peripheral edge portion 144a. The extension lengths of the first non-coating portion joining portions 144b may be approximately the same. The first non-coating portion joining portions 144b may be joined to the folded surface region F1 of the first non-coating portion 146a by welding. A weld pattern 144f formed by welding the first non-coating portion joining portions 144b to the folded surface region W1 may have a structure extending along the radial direction of the electrode assembly 110. The weld pattern 144f may be an array of lines or dots.

[0373] The terminal coupling portion 144c may be disposed to be surrounded by the plurality of first non-coating portion coupling portions 144b. The terminal coupling portion 144c may be coupled to the terminal 172 by welding. The bridge portion 144d may be located between a pair of adjacent first non-coating portion coupling portions 144b. In this case, the distance from the bridge portion 144d to one of the pair of first non-coating portion coupling portions 144b along the extension direction of the peripheral portion 144a may be approximately the same as the distance from the bridge portion 144d to the other of the pair of first non-coating portion coupling portions 144b along the extension direction of the peripheral portion 144a. The cross-sectional area of ​​each of the plurality of first non-coating portion coupling portions 144b may be approximately the same. The width and thickness of each of the plurality of first non-coating portion coupling portions 144b may be approximately the same.

[0374] Although not shown, a plurality of bridge portions 144d may be provided. Each of the plurality of bridge portions 144d may be disposed between an adjacent pair of first non-coating portion joining portions 144b. The plurality of bridge portions 144d may be disposed at substantially equal intervals from one another along the extension direction of the peripheral portion 144a. The distance from each of the plurality of bridge portions 144d to one of the adjacent pair of first non-coating portion joining portions 144b along the extension direction of the peripheral portion 144a may be substantially the same as the distance to the other first non-coating portion joining portion 144b.

[0375] As described above, when a plurality of first uncoated portion joining portions 144b and / or bridge portions 144d are provided, if the distance between the first uncoated portion joining portions 144b and / or the distance between the bridge portions 144d and / or the distance between the first uncoated portion joining portions 144b and the bridge portions 144d are constant, a current can smoothly flow from the first uncoated portion joining portions 144b to the bridge portions 144d or from the bridge portions 144d to the first uncoated portion joining portions 144b.

[0376] Meanwhile, the first current collector 144 and the folded surface region F1 of the first un-coated portion 146a may be joined by welding, for example, laser welding, ultrasonic welding, spot welding, etc. Preferably, the welded region may overlap the uniform lamination number section W1 of the folded surface region F1 by at least 50%.

[0377] The bridge portion 144d may include a notch N formed to partially reduce the cross-sectional area of ​​the bridge portion 144d. The adjustment of the cross-sectional area of ​​the notch N may be achieved, for example, by partially reducing the width and / or thickness of the bridge portion 144d. When the notch N is provided, the electrical resistance in the region where the notch N is formed increases, thereby enabling rapid current interruption when an overcurrent occurs.

[0378] The notched portion N is preferably provided in a region corresponding to the uniform lamination section of the electrode assembly 110 to prevent foreign matter generated during breakage from entering the electrode assembly 110. This is because the number of laminations of the divided segments is maximized in this region in the first uncoated portion 146a, allowing the overlapping divided segments to function as a mask. For example, the notched portion N may be provided in the region where the number of laminations of the first uncoated portion 146a is maximized in the uniform lamination section.

[0379] FIG. 13 is a top view showing the structure of a second current collector 176 according to an embodiment of the present invention.

[0380] 13, the second current collector 176 is disposed at the bottom of the electrode assembly 110. The second current collector 176 may be configured to electrically connect the uncoated portion 146b of the electrode assembly 110 to the battery housing 171. The second current collector 176 is made of a conductive metal material and is connected to the uncoated portion 146b. The second current collector 176 is electrically connected to the battery housing 171. The second current collector 176 may be interposed and fixed between the inner surface of the battery housing 171 and the first gasket 178b. Specifically, the second current collector 176 may be interposed between the lower surface of the beading portion 180 of the battery housing 171 and the first gasket 178b. However, this is not intended to limit the present invention, and the second current collector 176 may alternatively be welded to the inner wall surface of the battery housing 171 in an area where the beading portion 180 is not formed.

[0381] The second current collector 176 may include a support portion 176a disposed under the electrode assembly 110, a second non-coating portion coupling portion 176b extending from the support portion 176a generally along the radial direction of the electrode assembly 110 and coupled to the bent surface region F2 of the non-coating portion 146b, and a housing coupling portion 176c extending from the support portion 176a along the radial direction of the electrode assembly 110 and coupled to the inner surface of the battery housing 171. The second non-coating portion coupling portion 176b and the housing coupling portion 176c are indirectly connected to each other via 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, damage to the coupling portions between the second current collector 176 and the electrode assembly 110 and between the second current collector 176 and the battery housing 171 can be minimized. However, the second current collector 176 of the present invention is not limited to having a structure in which the second uncoated portion coupling portion 176b and the housing coupling portion 176c are indirectly coupled. For example, the second current collector 176 may have a structure without the support portion 176a that indirectly couples the second uncoated portion coupling portion 176b and the housing coupling portion 176c and / or a structure in which the uncoated portion 146b and the housing coupling portion 176c are directly coupled.

[0382] The support portion 176a and the second uncoated portion joining portion 176b are disposed at the bottom of the electrode assembly 110. The second uncoated portion joining portion 176b is joined to the bent surface region F2 of the uncoated portion 146b. The support portion 176a as well as the second uncoated portion joining portion 176b may be joined to the uncoated portion 146b. The second uncoated portion joining portion 176b and the uncoated portion 146b may be joined by welding. If a beading portion 180 is formed on the battery housing 171, the support portion 176a and the second uncoated portion joining portion 176b are located above the beading portion 180.

[0383] The support portion 176a includes a current collecting plate hole 176d formed at a position corresponding to a hole formed in the core C of the electrode assembly 110. The core C of the electrode assembly 110 and the current collecting plate hole 176d, which are connected to each other, may function as a passage for inserting a welding rod or irradiating a laser beam for welding between the terminal 172 and the terminal coupling portion 144c of the first current collector 144. The current collecting plate hole 176d may have a diameter approximately equal to or larger than that of the hole formed in the core C of the electrode assembly 110. When a plurality of second non-coating portion coupling portions 176b are provided, the plurality of second non-coating portion coupling portions 176b may extend radially from the support portion 176a of the second current collector 176 toward the sidewall of the battery housing 171. The plurality of second non-coating portion coupling portions 176b may be spaced apart from each other along the circumference of the support portion 176a.

[0384] A plurality of the housing coupling portions 176c may be provided. In this case, the plurality of housing coupling portions 176c may extend radially from the center of the second current collector 176 toward the sidewall of the battery housing 171. This allows electrical connection between the second current collector 176 and the battery housing 171 at multiple points. By coupling for electrical connection at multiple points, the coupling area can be maximized and electrical resistance can be minimized. The plurality of housing coupling portions 176c may be spaced apart from one another along the periphery of the support portion 176a. At least one housing coupling portion 176c may be located between adjacent second non-coating portion coupling portions 176b. The plurality of housing coupling portions 176c may be coupled to the inner surface of the battery housing 171, for example, to the beading portion 180. The housing coupling portion 176c may be coupled to the lower surface of the beading portion 180 by welding. The welding may be performed using, for example, laser welding, ultrasonic welding, or spot welding. By welding the housing coupling portion 176c onto the beading portion 180 in this manner, the resistance level of the cylindrical battery 200 can be limited to approximately 4 mΩ or less. In addition, by forming the lower surface of the beading portion 180 to extend in a direction approximately parallel to the upper surface of the battery housing 171, i.e., in a direction approximately perpendicular to the sidewall of the battery housing 171, and forming the housing coupling portion 176c to extend in the same direction, i.e., in the radial and circumferential directions, the housing coupling portion 176c can be stably contacted onto the beading portion 180. In addition, because the housing coupling portion 176c stably contacts the flat portion of the beading portion 180 in this manner, welding between the two components can be performed smoothly, thereby improving the bonding strength between the two components and minimizing an increase in resistance at the bonding site.

[0385] The housing coupling portion 176c may include a contact portion 176e coupled to the inner surface of the battery housing 171, and a coupling portion 176f connecting the support portion 176a and the contact portion 176e.

[0386] The contact portion 176e is coupled to an inner surface of the battery housing 171. If a beading portion 180 is formed in the battery housing 171, the contact portion 176e may be coupled to the beading portion 180 as described above. More specifically, the contact portion 176e may be electrically connected to a flat portion formed on the lower surface of the beading portion 180 formed in the battery housing 171, and may be interposed between the lower surface of the beading portion 180 and the first gasket 178b. In this case, for stable contact and coupling, the contact portion 176e may extend a predetermined length in the beading portion 180 along the circumferential direction of the battery housing 171.

[0387] Meanwhile, the maximum distance from the center of the second current collector 176 to the end of the second uncoated portion joining portion 176b along the radial direction of the electrode assembly 110 is preferably equal to or smaller than the inner diameter of the battery housing 171 in the area where the beading portion 180 is formed, i.e., the minimum inner diameter of the battery housing 171. This is to prevent interference between the beading portion 180 and the second current collector 176 during a sizing process in which the battery housing 171 is compressed in the height direction, thereby preventing the electrode assembly 110 from being pressed by the second current collector 176.

[0388] The second non-coating portion joining portion 176b includes holes 176g. The holes 176g can be used as passages for electrolyte movement. A welding pattern 176h formed by welding the second non-coating portion joining portion 176b to the bent surface region F2 can have a structure extending along the radial direction of the electrode assembly 110. The welding pattern 176h can be an array of lines or dots.

[0389] The cylindrical battery 200 according to an embodiment of the present invention has the advantage that electrical connections can be made at the top.

[0390] FIG. 14 is a top view showing a state in which a plurality of cylindrical batteries 200 are electrically connected, and FIG. 15 is a partially enlarged view of FIG.

[0391] 14 and 15, a plurality of cylindrical batteries 200 may be connected in series and parallel at the top of the cylindrical batteries 200 using bus bars 210. The number of cylindrical batteries 200 may be increased or decreased depending on the capacity of the battery pack.

[0392] In each cylindrical battery 200, the terminal 172 may have a positive polarity, and the flat surface 171a around the terminal 172 of the battery housing 171 may have a negative polarity. Of course, the opposite is also possible.

[0393] Preferably, a plurality of cylindrical batteries 200 may be arranged in a plurality of rows and columns. In the drawings, columns are in the vertical direction and rows are in the horizontal direction. Furthermore, to maximize space efficiency, the cylindrical batteries 200 may be arranged in the closest packing structure. The closest packing structure is formed when an equilateral triangle is drawn when the centers of the terminals 172 exposed to the exterior of the battery housing 171 are connected to each other. Preferably, the bus bars 210 connect the cylindrical batteries 200 arranged in the same column in parallel with each other and connect the cylindrical batteries 200 arranged in two adjacent columns in series with each other.

[0394] Preferably, the bus bar 210 may include a body portion 211, a plurality of first bus bar terminals 212, and a plurality of second bus bar terminals 213 for series and parallel connection. The body portion 211 may extend along the row of cylindrical batteries 200 between adjacent terminals 172. Alternatively, the body portion 211 may extend along the row of cylindrical batteries 200 but be bent regularly, such as in a zigzag shape.

[0395] The plurality of first bus bar terminals 212 may extend from one side of the body portion 211 and be electrically coupled to terminals 172 of the cylindrical battery 200 located in the extension direction. The electrical coupling between the first bus bar terminals 212 and the terminals 172 may be performed by laser welding, ultrasonic welding, or the like.

[0396] The plurality of second bus bar terminals 213 may extend from the other side of the body portion 211 and be electrically connected to the flat surface 171a around the terminals 172 positioned in the extension direction. The electrical connection between the second bus bar terminals 213 and the flat surface 171a may be performed by laser welding, ultrasonic welding, or the like.

[0397] Preferably, the body portion 211, the plurality of first bus bar terminals 212, and the plurality of second bus bar terminals 213 may be formed from a single conductive metal plate. The metal plate may be, for example, an aluminum plate or a copper plate, but the present invention is not limited thereto. Alternatively, the body portion 211, the plurality of first bus bar terminals 212, and the second bus bar terminals 213 may be manufactured as separate pieces and then joined together by welding or the like.

[0398] The cylindrical battery 200 of the present invention described above has a structure in which resistance is minimized by expanding the welding area through the folded surface regions F1 and F2, multiplexing the current path using 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 positive and negative electrodes, i.e., between the terminal 172 and the surrounding flat surface 171a, may be 0.5 mΩ to 4 mΩ, and preferably 1 mΩ to 4 mΩ, which is suitable for fast charging.

[0399] In the cylindrical battery 200 according to the present invention, the terminal 172 having a positive polarity and the flat surface 171a having a negative polarity are positioned in the same direction, so that electrical connection between the cylindrical batteries 200 can be easily realized using the bus bar 210.

[0400] In addition, since the terminal 172 of the cylindrical battery 200 and the surrounding flat surface 171a have a large area, the connection area of ​​the bus bar 210 can be sufficiently secured, thereby sufficiently reducing the resistance of the battery pack including the cylindrical battery 200.

[0401] The cylindrical battery according to the above-described embodiment (variation) is used to manufacture a battery pack.

[0402] FIG. 16 is a diagram schematically illustrating the configuration of a battery pack according to an embodiment of the present invention.

[0403] 16, a battery pack 300 according to one embodiment of the present invention includes an assembly of electrically connected cylindrical batteries 301 and a pack housing 302 that accommodates the assembly. The cylindrical batteries 301 may be any one of the batteries according to the above-described embodiments (variants). For convenience of illustration, components such as bus bars for electrical connection of the cylindrical batteries 301, a cooling unit, and external terminals are not shown.

[0404] The battery pack 300 is mounted on a vehicle. The vehicle may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The vehicle may be a four-wheeled vehicle or a two-wheeled vehicle.

[0405] FIG. 17 is a diagram illustrating a vehicle including the battery pack 300 of FIG.

[0406] 17, an automobile V according to an embodiment of the present invention includes a battery pack 300 according to an embodiment of the present invention. The automobile V operates by receiving a supply of power from the battery pack 300 according to an embodiment of the present invention.

[0407] According to one aspect of the present invention, when the uncoated portions exposed at both ends of the electrode assembly are folded, a sufficient area is secured in the radial direction of the electrode assembly so that 10 or more uncoated portions overlap, thereby preventing damage to the separator and the active material layer when the current collector is welded.

[0408] According to another aspect of the present 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 facilitating the electrolyte injection process and the welding process of the battery housing and the current collector.

[0409] According to yet another aspect of the present invention, an electrode assembly with improved energy density and reduced resistance can be provided by directly welding a folded surface area of ​​a non-coating portion to a current collector instead of using a strip-shaped electrode tab.

[0410] According to yet another aspect of the present invention, there are provided a cylindrical battery having a structure in which internal resistance is low and welding strength between a current collector and an uncoated portion is improved, a battery pack including the same, and a vehicle.

[0411] As described above, the present invention has been described using limited embodiments and drawings, but the present invention is not limited thereto, and it goes without saying that various modifications and variations can be made by a person having ordinary knowledge in the technical field to which the present invention pertains within the technical spirit of the present invention and the equivalent scope of the claims.

[0412] Furthermore, the present invention may include the following aspects. [Section 1] An electrode assembly in which a first electrode, a second electrode, and a separator interposed therebetween are wound around a shaft to define a core and an outer circumferential surface, the first electrode includes a non-coating portion at a long side end thereof, the non-coating portion being exposed to the outside of the separator along a winding axis direction of the electrode assembly; an electrode assembly, wherein a portion of the uncoated portion is folded in a radial direction of the electrode assembly to form a folded surface region including overlapping layers of the uncoated portion, and in a portion of the folded surface region, the number of stacked uncoated portions in the winding axis direction of the electrode assembly is 10 or more. [Section 2] The total number of winding turns of the first electrode is defined as n1, and the winding turn index k (a natural number from 1 to n1) at the kth winding turn position is divided by the total number of winding turns n1 to obtain the relative radial position R with respect to the winding turn index k. 1,k If we define it as follows, R satisfies the condition that the number of layers in the plain area is 10 or more. 1,k Item 2. The electrode assembly according to item 1, wherein the ratio of the length of the radial direction section to the relative radial position section where the uncoated portion is folded is at least 30%. [Section 3] R that meets the condition that the number of layers in the plain area is 10 or more 1,k Item 3. The electrode assembly according to item 2, wherein the ratio of the length of the radial direction section to the relative radial position section where the uncoated portion is bent is 30% to 85%. [Section 4] the second electrode includes a non-coating portion at a long side end thereof, the non-coating portion being exposed to the outside of the separator along the winding axis direction of the electrode assembly; 4. The electrode assembly according to any one of items 1 to 3, wherein a portion of the uncoated portion is folded in a radial direction of the electrode assembly to form a folded surface region including overlapping layers of the uncoated portion, and in a portion of the folded surface region, the number of stacked uncoated portions in the winding axis direction of the electrode assembly is 10 or more. [Section 5] The total number of winding turns of the second electrode is defined as n2, and the winding turn index k (a natural number from 1 to n2) at the kth winding turn position is divided by the total number of winding turns n2 to obtain the relative radial position R with respect to the winding turn index k. 2,k If we define it as follows, R satisfies the condition that the number of layers in the plain area is 10 or more. 2,k Item 5. The electrode assembly according to item 4, wherein the ratio of the length of the radial direction section to the relative radial position section where the uncoated portion is bent is at least 30%. [Section 6] R that meets the condition that the number of layers in the plain area is 10 or more 2,k Item 6. The electrode assembly according to item 5, wherein the ratio of the length of the radial direction section to the relative radial position section where the uncoated portion is bent is 30% to 85%. [Section 7] In the winding structure of the first electrode, the relative radial position R of the first winding turn 1,1 The first relative radial position R of the k*th winding turn preset from 1,k* The height of the plain area in the section up to the relative radial position R of the winding turn number k*+1 1,k*+1 Item 3. The electrode assembly according to item 2, wherein the height of the uncoated portion in the section from the first position to the second position is lower than the height of the uncoated portion in the section from the first position to the second position. [Section 8] In the winding structure of the first electrode, the relative radial position R of the first winding turn 1,1 The first relative radial position R of the k*th winding turn preset from1,k* Item 3. The electrode assembly according to item 2, wherein the height of the plain portion in the section up to is lower than the folded surface region formed by overlapping folded plain portions. [Section 9] In the winding structure of the first electrode, the relative radial position R of the first winding turn 1,1 The first relative radial position R of the k*th winding turn from 1,k* Item 3. The electrode assembly according to item 2, wherein the uncoated portion in the section up to is not bent toward the core of the electrode assembly. [Section 10] In the winding structure of the second electrode, the relative radial position R of the first winding turn 2,1 The first relative radial position R of the k*th winding turn preset from 2,k* The height of the plain area in the section up to the k*+1th winding turn is the relative radial position R 2,k*+1 Item 6. The electrode assembly according to item 5, wherein the height of the uncoated portion in the section from the relative radial position 1 to the relative radial position 2 is lower than the height of the uncoated portion in the section from the relative radial position 1 to the relative radial position 2. [Section 11] Relative radius position R of the first winding turn 2,1 The first relative radial position R of the k*th winding turn preset from 2,k* Item 6. The electrode assembly according to item 5, wherein the height of the plain portion in the section up to is lower than the folded surface area formed by overlapping the folded plain portion. [Section 12] Relative radius position R of the first winding turn 2,1 The first relative radial position R of the k*th winding turn preset from 2,k* Item 6. The electrode assembly according to item 5, wherein the uncoated portion in the section up to is not bent toward the core of the electrode assembly. [Section 13] Item 5. The electrode assembly according to item 1 or 4, wherein the uncoated portion of the first electrode or the uncoated portion of the second electrode is divided into a plurality of segments that can be bent independently. [Section 14] Each of the plurality of segments has a geometric shape with the bent curve as a base, Item 14. The electrode assembly according to item 13, wherein the geometrical figure is a combination of one or more straight lines, one or more curved lines, or a combination thereof. [Section 15] Item 15. The electrode assembly according to item 14, wherein the width of the geometrical shape decreases stepwise or continuously from the base to the top. [Section 16] Item 16. The electrode assembly according to item 15, wherein a lower interior angle formed by a base of the geometrical figure and a side that intersects with the base is 60° to 85°. [Section 17] Item 17. The electrode assembly according to item 16, wherein the lower interior angles of the plurality of segments increase stepwise or gradually along a direction parallel to the winding direction of the electrode assembly. [Section 18] Each of the plurality of segment pieces has a trapezoidal shape with the bend line as a base, The radius of the winding turn on which the segment is arranged based on the core center of the electrode assembly is defined as r, and the arc length of the winding turn corresponding to the lower part of the segment is defined as L. arc The lower interior angle of the segment when the assumption that the sides of a pair of segments arranged adjacent to a winding turn of radius r are parallel is applied is defined as θ assumption Then, the actual lower interior angle θ of the adjacently arranged pair of segments is real is expressed as the following formula 1 [Formula 1] θ real >θ assumption θ assumption =90°-360°×(L arc / 2πr)×0.5 Item 18. The electrode assembly according to any one of items 14 to 17, [Section 19] The arc length L of the winding turn corresponding to the lower part of the segment based on the core center of the electrode assembly arc Item 19. The electrode assembly according to item 18, wherein the corresponding inclined angle is 45° or less. [Section 20] The overlapping ratio between adjacent electrode segments arranged in a winding turn of radius r based on the core center of the electrode assembly is expressed by the formula (θ real / θ assumption Item 20. The electrode assembly according to item 18 or 19, wherein the overlapping ratio of the two segments is greater than 0 and less than or equal to 0.05 when defined as (1). [Section 21] Item 15. The electrode assembly according to item 14, wherein when a virtual circle is drawn through adjacent pairs of segments arranged in a winding turn of radius r based on the core center of the electrode assembly, pairs of arcs passing through each segment overlap. [Section 22] Item 22. The electrode assembly according to item 21, wherein the ratio of the length of the overlapping arc to the length of the arc passing through each segment is defined as the overlap ratio of the segment, and the overlap ratio of the segment is greater than 0 and less than or equal to 0.05. [Section 23] In the winding structure of the first electrode, the relative radial position R of the first winding turn 1,1 The first relative radial position R of the k*th winding turn from 1,k* The height of the plain area in the section up to the relative radial position R 1,k*+1 Item 3. The electrode assembly according to item 2, wherein the height of the uncoated portion is lower than the height of the uncoated portion in the section from to relative radial position 1 and is not bent toward the core side. [Section 24] Relative Radius Position R 1,1 From R 1,k* The length of the first electrode corresponding to the relative radial position R 1,k*+1 Item 24. The electrode assembly according to item 23, wherein the length of the first electrode corresponding to the relative radial position 1 is 1% to 30%. [Section 25] In the winding structure of the first electrode, the relative radial position R of the k*+1th winding turn 1,k*+1 Folded length of plain part fd 1,k*+1 is the relative radial position R of the first winding turn 1,1 k*th relative radial position R 1,k* Item 3. The electrode assembly according to item 2, wherein the radial length is shorter than the length of the electrode assembly. [Section 26] In the winding structure of the first electrode, the core radius of the electrode assembly is r c When defined as 0.90r from the center of the core c The relative radial position R of the k*+1th winding turn in the section 1,k*+1 Item 3. The electrode assembly according to item 2, wherein the electrode assembly is not blocked by the bent portion of the plain portion located in the section from 1 to 1. [Section 27] Relative radial position R of the k*+1th winding turn 1,k*+1 Folded length of plain part fd1,k*+1 , the radius of the core r c , and the relative radial position R 1,k*+1 is the distance d from the center of the electrode assembly 1,k*+1 is expressed by the following formula 2 [Formula 2] fd 1,k*+1 +0.90×r c ≦d 1,k*+1 Item 27. The electrode assembly according to item 26, [Section 28] In the winding structure of the second electrode, the relative radial position R of the first winding turn 2,1 The first relative radial position R of the k*th winding turn from 2,k* The height of the plain area in the section up to the k*+1th winding turn is the relative radial position R 2,k*+1 Item 6. The electrode assembly according to item 5, wherein the height of the uncoated portion in the section from to relative radial position 1 is lower than the height of the uncoated portion in the section from to relative radial position 2, and the uncoated portion is not bent toward the core side. [Section 29] Relative Radius Position R 2,1 From R 2,k* The length of the second electrode corresponding to the relative radial position R 2,k*+1 Item 29. The electrode assembly according to item 28, wherein the length of the second electrode corresponding to the relative radial position 1 is 1% to 30%. [Section 30] In the winding structure of the second electrode, the relative radial position R of the k*+1th winding turn 2,k*+1 The folded length of the plain part located at fd 2,k*+1 is the relative radial position R of the first winding turn 2,1 The first relative radial position R of the k*th winding turn from 2,k* Item 6. The electrode assembly according to item 5, wherein the radial length is shorter than the length of the electrode assembly. [Section 31] In the winding structure of the second electrode, the core radius of the electrode assembly is r c When defined as 0.90r from the center of the core c The relative radial position R of the k*+1th winding turn in the section 2,k*+1 Item 6. The electrode assembly according to item 5, wherein the uncoated portion of the second electrode located in the section from the first position to the relative radial position 1 is not blocked by the bent portion. [Section 32] Relative radial position R of the k*+1th winding turn 2,k*+1 Folded length of plain part fd 2,k*+1 , the radius of the core r c , and the relative radial position R 2,k*+1 is the distance d from the center of the electrode assembly 2,k*+1 is expressed by the following formula 3. [Formula 2] fd 2,k*+1 +0.90×r c ≦d 2,k*+1 Item 32. The electrode assembly according to item 31, [Section 33] In the winding structure of the first electrode, the relative radial position R of the k*+1th winding turn 1,k*+1 Pre-set from

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Claims

[Claim 1] An electrode assembly in which a first electrode, a second electrode, and a separator interposed therebetween are wound around a shaft to define a core and an outer circumferential surface, the first electrode includes a non-coating portion at a long side end thereof, the non-coating portion being exposed to the outside of the separator along a winding axis direction of the electrode assembly; an electrode assembly, wherein a portion of the uncoated portion is folded in a radial direction of the electrode assembly to form a folded surface region including overlapping layers of the uncoated portion, and in a portion of the folded surface region, the number of stacked uncoated portions in a winding axis direction of the electrode assembly is 10 or more.

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