CN116783771A - Electrode assembly, battery pack including the same, and vehicle - Google Patents

Abstract

An electrode assembly, a battery pack including the battery, and a vehicle are disclosed. The electrode assembly includes a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode, the first electrode, the second electrode, and the separator being wound around one axis to define a core and an outer circumferential surface, wherein the first electrode includes an uncoated portion exposed to an outside of the separator in a winding axis direction at a long side end thereof, a portion of the uncoated portion is locally bent in a radial direction of the electrode assembly to form a bent surface region, and the uncoated portion may have a number of layers greater than or equal to 10 in a winding axis direction of the electrode assembly in a portion of the bent surface region.

Description

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

Technical field

The present disclosure relates to an electrode assembly as well as a battery, a battery pack, and a vehicle including the electrode assembly. This application claims priority from the following patent applications: Korean Patent Application No. 10-2021-0007278 filed in South Korea on January 19, 2021;

Korean Patent Application No. 10-2021-0022897 filed in South Korea on February 19, 2021;

Korean Patent Application No. 10-2021-0022894 filed in South Korea on February 19, 2021;

Korean Patent Application No. 10-2021-0022891 filed in South Korea on February 19, 2021;

Korean Patent Application No. 10-2021-0022881 filed in South Korea on February 19, 2021;

Korean Patent Application No. 10-2021-0024424 filed in South Korea on February 23, 2021;

Korean patent application number 10-2021-0030300 filed in South Korea on March 8, 2021;

Korean Patent Application No. 10-2021-0030291 filed in South Korea on March 8, 2021;

Korean Patent Application No. 10-2021-0046798 filed in South Korea on April 9, 2021;

Korean Patent Application No. 10-2021-0058183 filed in South Korea on May 4, 2021;

Korean Patent Application No. 10-2021-0077046 filed in South Korea on June 14, 2021;

Korean Patent Application No. 10-2021-0084326 filed in South Korea on June 28, 2021;

Korean Patent Application No. 10-2021-0131225 filed in South Korea on October 1, 2021;

Korean Patent Application No. 10-2021-0131215 filed in South Korea on October 1, 2021;

Korean Patent Application No. 10-2021-0131205 filed in South Korea on October 1, 2021;

Korean patent application number 10-2021-0131208 filed in South Korea on October 1, 2021;

Korean Patent Application No. 10-2021-0131207 filed in South Korea on October 1, 2021;

Korean patent application number 10-2021-0137001 filed in South Korea on October 14, 2021;

Korean Patent Application No. 10-2021-0137856 filed in South Korea on October 15, 2021;

Korean Patent Application No. 10-2021-0142196 filed in South Korea on October 22, 2021;

Korean Patent Application No. 10-2021-0153472 filed in South Korea on November 9, 2021;

Korean Patent Application No. 10-2021-0160823 filed in South Korea on November 19, 2021;

Korean Patent Application No. 10-2021-0163809 filed in South Korea on November 24, 2021;

Korean Patent Application No. 10-2021-0165866 filed in South Korea on November 26, 2021;

Korean Patent Application No. 10-2021-0172446 filed in South Korea on December 3, 2021;

Korean Patent Application No. 10-2021-0177091 filed in South Korea on December 10, 2021;

Korean Patent Application No. 10-2021-0194593 filed in South Korea on December 31, 2021;

Korean Patent Application No. 10-2021-0194610 filed in South Korea on December 31, 2021;

Korean Patent Application No. 10-2021-0194572 filed in South Korea on December 31, 2021;

Korean Patent Application No. 10-2021-0194612 filed in South Korea on December 31, 2021;

Korean Patent Application No. 10-2021-0194611 filed in South Korea on December 31, 2021; and

Korean patent application number 10-2022-0001802 filed in South Korea on January 5, 2022,

The disclosures of which are incorporated herein by reference.

Background technique

Secondary batteries that are easily applicable to various product groups and have electrical characteristics such as high energy density are commonly used not only in portable devices but also in electric vehicles (EVs) or hybrid electric vehicles (EVs) driven by electric driving sources. HEV).

Because these secondary batteries have the primary advantage of significantly reducing the use of fossil fuels and the secondary advantage of producing no by-products from the use of energy, they are attracting attention as a new energy source for improving eco-friendliness and energy efficiency. .

Currently, the secondary battery types widely used in this field include lithium-ion batteries, lithium polymer batteries, nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, etc. The operating voltage of the unit secondary battery (ie, unit cell) is about 2.5V to 4.5V. Therefore, when a higher output voltage is required, a battery pack can be configured by connecting multiple cells in series. In addition, multiple batteries can be connected in parallel to form a battery pack according to the required charge/discharge capacity of the battery pack. Therefore, the number of batteries included in the battery pack and the form of electrical connection can be variously set according to the required output voltage and/or charge/discharge capacity.

Meanwhile, as a unit secondary battery, cylindrical, rectangular, and pouch-type batteries are known. In the case of a cylindrical battery, a separator serving as an insulator is interposed between the positive and negative electrodes, and they are rolled to form an electrode assembly in the form of a roll core, which is inserted into the battery case to configure the battery. Furthermore, a strip-shaped electrode tab may be connected to the uncoated portion of each of the positive electrode and the negative electrode, and the electrode tab electrically connects the electrode assembly and the electrode terminal exposed to the outside. For reference, the positive terminal is the cap of the sealing body that seals the opening of the battery case, and the negative terminal is the battery case. However, according to the conventional cylindrical battery having such a structure, since the current is concentrated in the bar-shaped electrode joint connected to the uncoated portion of the positive electrode and/or the uncoated portion of the negative electrode, the current collection efficiency is due to large resistance and a large amount of Fever and relatively poor.

For small cylindrical cells with a form factor of 1865 (diameter: 18mm, height: 65mm) or a form factor of 2170 (diameter: 21mm, height: 70mm), resistance and heat are not major issues. However, when the form factor is increased to apply cylindrical batteries to electric vehicles, the cylindrical battery may catch fire while generating a large amount of heat around the electrode joints during the fast charging process.

In order to solve this problem, a cylindrical battery (so-called jointless cylindrical battery) is provided, in which the uncoated portion of the positive electrode and the uncoated portion of the negative electrode are designed to be positioned at the top and bottom of the core-type electrode assembly, respectively, And the current collector is welded to the uncoated part to improve the current collection efficiency.

1 to 3 are diagrams showing a process of manufacturing a jointless cylindrical battery. Figure 1 shows the structure of the electrode, Figure 2 shows the process of winding the electrode, and Figure 3 shows the process of welding the current collector to the bent surface area of the uncoated portion.

Referring to FIGS. 1 to 3 , the positive electrode 10 and the negative electrode 11 have a structure in which a sheet-like current collector 20 is coated with an active material 21 and includes an uncoated electrode at one long side along the winding direction X. Cover 22.

As shown in FIG. 2 , the electrode assembly A is manufactured by sequentially stacking the positive electrode 10 and the negative electrode 11 together with two sheets of separators 12 and then winding them in one direction X. At this time, 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 changed opposite to those shown in the figure.

After the winding process, the uncoated portion 10a of the positive electrode 10 and the uncoated portion 11a of the negative electrode 11 are bent toward the core to form a bent surface area. Thereafter, the current collectors 30, 31 are welded and coupled to the uncoated portions 10a, 11a, respectively.

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

In a jointless cylindrical battery, in order to improve the welding characteristics between the uncoated parts 10a, 11a and the current collectors 30, 31, strong pressure must be applied to the welding areas of the uncoated parts 10a, 11a to make the uncoated parts 10a and 11a are bent as flat as possible.

When the uncoated portions 10a, 11a are bent, all or most of the cavity 33 in the core of the electrode assembly A is blocked due to the bending of the uncoated portion 32 adjacent to the core of the electrode assembly A. In this case, problems are caused during electrolyte injection. That is, the cavity 33 in the core of the electrode assembly A serves as a channel for injecting electrolyte. However, electrolyte injection is difficult if the corresponding channels are blocked. Furthermore, when the electrolyte injector is inserted into the cavity 33, the electrolyte injector may interfere with the uncoated portion 32 that is bent near the core, which may cause the uncoated portion 32 to tear.

Furthermore, the bent portions of the uncoated portions 10a, 11a to which the current collectors 30, 31 are welded should overlap in multiple layers, and there should not be any empty space (gap). In this way, sufficient welding strength can be obtained, and even with the latest technology such as laser welding, laser light can be prevented from penetrating into the electrode assembly A and melting the separator or active material.

In order for the uncoated portions 10a, 11a to overlap in the same number of layers, the uncoated portions 10a, 11a located at corresponding positions based on the position of each winding turn must be bent toward the core and cover the inner winding turns The top surface of the uncoated portion is bent at . In addition, assuming that the interval between the winding turns is d, and the bending length of the uncoated portion 10a, 11a of each winding turn is e, the bending length e must be a ratio of d*n (n is greater than or A natural number equal to 2) greater length. Only in this case, a region is formed in which the uncoated portions 10a, 11a overlap in multiple layers by the same amount. Furthermore, in order to sufficiently obtain an area in which the uncoated portions 10a, 11a overlap by approximately the same amount in the radial direction of the electrode assembly, the uncoated portions 10a, 11a must have a sufficient length. However, since the electrode assembly included in the small cylindrical battery has a small radius, it is difficult to think of the motivation for the idea of designing the uncoated portions 10a, 11a with a sufficiently long bending length.

Contents of the invention

technical problem

The present disclosure aims to solve the problems of the prior art, and therefore the present disclosure relates to providing an electrode assembly having an uncoated portion bending structure, which is bent by the uncoated portions when exposed at both ends of the electrode assembly When welding the current collector, it is sufficient to ensure that the uncoated portion overlaps into an area of more than 10 layers in the radial direction of the electrode assembly, thereby preventing damage to the separator or active material layer when welding the current collector.

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

The present disclosure also relates to providing an electrode assembly with improved energy density and reduced electrical resistance.

The present disclosure is also directed to providing a cylindrical battery including an electrode assembly having an improved structure, a battery pack including the battery, and a vehicle including the battery pack.

The technical objects to be solved by the present disclosure are not limited to the above, and those skilled in the art will clearly understand other objects not mentioned herein from the following disclosure.

Technical solutions

In an aspect of the present disclosure, an electrode assembly in which a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode are wound based on an axis to define a core and a periphery, wherein the first electrode includes an uncoated portion exposed outside the separator at a long side end thereof and along a winding axis direction of the electrode assembly, and the uncoated portion A portion of the portion is bent along the radial direction of the electrode assembly to form a bent surface area including an overlapping layer of the uncoated portion, and in a local area of the bent surface area, the electrode In the direction of the winding axis of the component, the number of stacked layers of the uncoated portion is 10 or more.

In one embodiment, when the total number of winding turns of the first electrode is defined as n ₁ , and the winding turn index k at the k-th winding turn position is divided by the total number of winding turns n ₁ , it is obtained The value of is defined as the relative radial position R _1,k of the winding turn index k, based on the relative radial position area in which the uncoated part is bent, satisfying the stacking layer number of the uncoated part The length ratio of the radial region of R _1,k under the condition of 10 or more, where k is a natural number from 1 to n ₁ , may be 30% or more.

Preferably, based on the relative radial position area in which the uncoated portion is bent, the length ratio of the radial area of R _1,k that satisfies the condition that the number of stacked layers of the uncoated portion is 10 or more. Can be 30% to 85%.

In another embodiment, the second electrode may include an uncoated layer at a long end thereof and exposed outside the separator at a long end thereof along the winding axis direction of the electrode assembly. part, and a part of the uncoated part may be bent along the radial direction of the electrode assembly to form a bent surface area including an overlapping layer of the uncoated part, and in the bent In a local area of the surface area, the number of stacked layers of the uncoated portion may be 10 or more in the direction of the winding axis of the electrode assembly.

In yet another embodiment, when the total number of winding turns of the second electrode is defined as n ₂ , and the winding turn index k at the k-th winding turn position is divided by the total number of winding turns n ₂ The value obtained is defined as the relative radial position R _{2,k of the winding turn index k} , based on the relative radial position area in which the uncoated part is bent, satisfying the stacked layer of the uncoated part The length ratio of the radial region of R _{2, k} may be 30% or more under the condition that the number is 10 or more, where k is a natural number from 1 to n ₂ .

Preferably, based on the relative radial position area in which the uncoated portion is bent, the length ratio of the radial area of R _2,k satisfies the condition that the number of stacked layers of the uncoated portion is 10 or more. Can be 30% to 85%.

In yet another embodiment, in the winding structure of the first electrode, from the relative radial position R _1,1 of the first winding turn to the preset first relative radial position of the k ^*th winding turn The height of the uncoated portion of the area at position R _1,k* may be smaller than all the areas from the relative radial position R _1,k*+1 of the k*+1th winding turn to the relative radial position 1 The height of the uncoated part.

In yet another embodiment, in the winding structure of the first electrode, from the relative radial position R _1,1 of the first winding turn to the preset first relative radial position of the k ^*th winding turn The height of the uncoated portion of the area at position R _1,k* may be smaller than the height of the bent surface area formed by the overlap of the bent uncoated portions.

In yet another embodiment, the uncoated portion of the area from the relative radial position R _1,1 of the 1st winding turn to the first relative radial position R _1,k* of the k ^* th winding turn It may not be bent toward the core of the electrode assembly.

In yet another embodiment, in the winding structure of the second electrode, from the relative radial position R _2,1 of the first winding turn to the preset first relative radial position of the k ^*th winding turn The height of the uncoated portion of the area at position R _2,k* may be smaller than all the areas from the relative radial position R _2,k*+1 of the k*+1th winding turn to the relative radial position 1 The height of the uncoated part.

In yet another embodiment, in the winding structure of the second electrode, from the relative radial position R _2,1 of the first winding turn to the preset first relative radial position of the k ^*th winding turn The height of the uncoated portion of the area at position R _2,k* may be smaller than the height of the bent surface area formed by the overlap of the bent uncoated portions.

In yet another embodiment, the unscheduled area from the relative radial position R _2,1 of the first winding turn to the preset first relative radial position R _2,k* of the k ^* th winding turn is The coating portion may not be bent toward the core of the electrode assembly.

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

Preferably, each of the plurality of sections may have a geometric shape having its bend line as a base, and the geometric shapes may be connected by one or more straight lines, one or more curves, or a combination thereof And formed.

In one embodiment, the geometric shape may have a gradually or continuously decreasing width from the base to the top.

In another embodiment, the lower internal angle of the geometry between the base and the side intersecting the base may be from 60 to 85 degrees.

In yet another embodiment, the lower inner angles of the plurality of sections may gradually or gradually increase in a direction parallel to the winding direction of the electrode assembly.

In yet another embodiment, each of the plurality of sections may have a geometry with a bend line as a base, and when provided with the winding turns of the sections based on the core of the electrode assembly The radius of the center is r, the arc length of the lower part of the winding turn corresponding to the section is L _arc , and it is assumed that the side of a pair of adjacent sections in the winding turn with the radius r When the lower internal angle of the section is θ _assumption , the actual lower internal angle θ _real of the pair of adjacent sections can satisfy the following formula:

θ _real >θ _assumption

θ _assumption =90°-360°*(L _arc /2πr)*0.5.

In yet another embodiment, based on the core center of the electrode assembly, a circumferential angle corresponding to an arc length L _arc of the winding turns corresponding to the lower portion of the section may be 45 degrees or less. .

In yet another embodiment, when the formula θ _real /θ _assumptoin -1 is used to define the overlap ratio of adjacently arranged sections in the winding turns of radius r, the overlap ratio of the sections may be greater than 0 and equal to or less than 0.05.

In yet another embodiment, when a virtual circle is drawn through a pair of adjacently disposed segments in a winding turn of radius r based on the core center of the electrode assembly, the A pair of arcs can overlap each other.

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, the overlap ratio of the segment may be greater than 0 and equal to or less than 0.05.

In yet another embodiment, in the winding structure of the first electrode, from the relative radial position R _1,1 of the 1st winding turn to the first relative radial position R ₁ of the k ^*th winding turn _{, the uncoated portion of the area k*} may have a ratio of the uncoated portion of the area from the relative radial position R _1,k*+1 of the k*+1th winding turn to the relative radial position 1 The portion is of small height and may not be bent toward the core.

In yet another embodiment, the length of the first electrode corresponding to the area from the relative radial position R _1,1 to the first relative radial position R _1,k* is equal to the length of the first electrode The ratio corresponding to the length from the relative radial position R _1,k*+1 to the relative radial position 1 may be 1% to 30%.

In yet another embodiment, in the winding structure of the first electrode, the bending of the uncoated portion at the relative radial position R _{1 of the k*+1th winding turn, k*+1} The length fd _1,k*+1 may be shorter than the radial length from the relative radial position R _1,1 of the 1st winding turn to the relative radial position R _1,k* of the k*th winding turn.

In yet another embodiment, in the wound structure of the first electrode, when the radius of the core of the electrode assembly is defined as r _c , the area from the center of the core to 0.90 r _c may not be The bend of said uncoated portion located in the area from the relative radial position R _1,k*+1 of the k*+1th winding turn to the relative radial position 1 blocks.

In yet another embodiment, the bending length fd 1 _{,k*+1 of the uncoated portion at the relative radial position R 1,k*+ 1 of the k*+1th winding turn} , the core The radius r _c and the distance d _1,k*+1 from the center of the electrode assembly to the relative radial position R 1 _,k*+1 can satisfy the following formula:

fd _1,k*+1 +0.9*r _c ≤d _1,k*+1 .

In yet another embodiment, in the winding structure of the second electrode, from the relative radial position R _2,1 of the first winding turn to the preset first relative radial position of the k ^*th winding turn The uncoated portion of the area at position R _2,k* may have a greater value than the area from the relative radial position R _{2,k*+1 of the k*+1th} winding turn to the relative radial position 1 The uncoated portion has a small height and may not be bent toward the core.

In yet another embodiment, the length of the second electrode corresponding to the area from the relative radial position R _2,1 to the first relative radial position R _2,k* is equal to the length of the second electrode The ratio corresponding to the length of the area from the relative radial position R _2,k*+1 to the relative radial position 1 may be 1% to 30%.

In yet another embodiment, in the winding structure of the second electrode, the bending of the uncoated portion at the relative radial position R _{2 of the k*+1th winding turn, k*+1} The length fd _2,k*+1 may be shorter than the radial length from the relative radial position R _2,1 of the 1st winding turn to the relative radial position R _1,k* of the k*th winding turn.

In yet another embodiment, in the wound structure of the first electrode, when the radius of the core of the electrode assembly is defined as r _c , an area from the center of the core C to 0.90 r _c may The bent portion of the uncoated portion of the second electrode located in the region from the relative radial position R _2,k*+1 of the k*+1th winding turn to the relative radial position 1 block.

In yet another embodiment, the bending length fd _{2,k*+1 of the uncoated portion at the relative radial position R 2,k*+} 1 of _{the k*+1th winding turn} , the core The radius r _c and the distance d _2,k*+1 from the center of the electrode assembly to the relative radial position R 2 _,k*+1 can satisfy the following formula:

fd _2,k*+1 +0.9*r _c ≤d _2,k*+1 .

In yet another embodiment, in the winding structure of the first electrode, from the relative radial position R _{1,k*+1 of the k*+1th} winding turn to the preset k@th winding turn The uncoated portion of the area of the second relative radial position R _1,k@ may be divided into a plurality of sections, the heights of the plurality of sections gradually or gradually increase along a direction parallel to the winding direction. big.

In yet another embodiment, the radial length of the area from the relative radial position R _1,k*+1 to the second relative radial position R _1,k@ is equal to the length of the first electrode. The ratio of the radii of the wound structure excluding the core of the electrode assembly may be 1% to 56%.

In yet another embodiment, in the winding structure of the first electrode, from the relative radial position R _{1,k@+1 of the preset k@+1th} winding turn to the relative radial position 1 The uncoated portion of the area may be divided into a plurality of sections, and the heights of the plurality of sections correspond to the height from the relative radial position R _1,k@+1 to the relative radial position 1 It can be roughly the same.

In yet another embodiment, in the winding structure of the second electrode, from the relative radial position R _{2,k*+1 of the k*+1th} winding turn to the preset k@th winding turn The uncoated portion of the area of the second relative radial position R _2,k@ may be divided into a plurality of sections, the heights of the plurality of sections gradually or gradually increase along a direction parallel to the winding direction. big.

In yet another embodiment, the radial length of the area from the relative radial position R _2,k*+1 to the second relative radial position R _2,k@ is equal to the length of the second electrode. The ratio of the radii of the wound structure excluding the core of the electrode assembly may be 1% to 56%.

In yet another embodiment, in the winding structure of the second electrode, the relative radial position R2 _{,k@+1 of the second electrode from the k@} +1th winding turn to the relative radial position The uncoated portion of the area of position 1 may be divided into a plurality of sections, and the heights of the plurality of sections vary from the relative radial position _R2,k@+1 to the relative radial position 1 can be about the same height.

In yet another embodiment, in the rolled structure of the first electrode, the uncoated portion bent along the radial direction of the electrode assembly may be divided into a plurality of regions that can be bent independently. segments, and at least one of the heights in the winding axis direction and the widths in the winding direction of the plurality of sections may be gradually individually or in groups along a direction parallel to the winding direction. Or gradually increase.

In yet another embodiment, in the wound structure of the second electrode, the uncoated portion bent along the radial direction of the electrode assembly may be divided into a plurality of regions that can be bent independently. segments, and at least one of the heights in the winding axis direction and the widths in the winding direction of the plurality of sections may be gradually individually or in groups along a direction parallel to the winding direction. Or gradually increase.

In yet another embodiment, each of the plurality of sections may satisfy at least one of the following conditions: a width condition of 1 mm to 11 mm along the winding direction; 2 mm along the winding axis direction. to a height condition of 10mm; and a separation spacing condition of 0.05mm to 1mm along the winding direction.

In yet another embodiment, cutting grooves may be interposed between the plurality of sections, and there may be between the bottom of the cutting groove and the active material layer of the first electrode or the second electrode. Set with a predetermined gap.

In yet another embodiment, the gap may have a length of 0.2 mm to 4 mm.

In yet another embodiment, the plurality of sections may form a plurality of section groups along the winding direction of the electrode assembly, and the widths of sections belonging to the same section group in the winding direction, At least one of the height in the winding axis direction and the separation pitch in the winding direction may be substantially the same as each other.

In yet another embodiment, the sections belonging to the same section group may be configured such that the width in the winding direction, the height in the winding axis direction, and the separation pitch in the winding direction are within At least one of gradually or gradually increases along a direction parallel to the winding direction of the electrode assembly.

In yet another embodiment, at least a portion of the plurality of segment groups may be disposed at the same winding turn of the electrode assembly.

In yet another embodiment, the bent surface area formed by the uncoated portion of the first electrode may include a stack from the periphery of the electrode assembly to the core of the electrode assembly A number increasing region and a stacking number uniform region, the stacking number increasing region may be defined as a region in which the number of stacked layers of the uncoated portion increases toward the core of the electrode assembly, and the stacking number uniform region may It is defined as the area from the radial position where the number of stacked layers of the uncoated portion stops increasing to the radial position where the uncoated portion begins to bend, and the radial length of the uniform stacking number area is the same as The ratio of the radial length of the winding turn where the uncoated part starts to bend to the winding turn where the uncoated part ends bending may be 30% or more.

In yet another embodiment, the bent surface area formed by the uncoated portion of the second electrode may include a stack from the periphery of the electrode assembly to the core of the electrode assembly a number increasing region and a stacking number uniform region, the stacking number increasing region may be defined as a region in which the number of stacked layers of the uncoated portion increases toward the core of the electrode assembly, and the stacking number is uniform The area may be defined as an area from a radial position where the number of stacked layers of the uncoated part stops increasing to a radial position where the uncoated part starts to bend, and the diameter of the area where the number of stacked layers is uniform is The ratio of the radial length to the radial length from the winding turn where the uncoated part starts to be bent to the winding turn where the uncoated part ends being bent may be 30% or more.

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

In yet another embodiment, the uncoated portion of the first electrode may have a thickness of 10 μm to 25 μm.

In yet another embodiment, the uncoated portion of the second electrode may have a thickness of 5 μm to 20 μm.

In yet another embodiment, in the partial area of the bent surface region formed by the uncoated portion of the first electrode, the total stack thickness of the overlapping layers of the uncoated portion Can be 100μm to 975μm.

In yet another embodiment, the uncoated portion of the first electrode may be divided into a plurality of independently bendable segments, and the first electrode may include highly variable height regions of the segments. and highly uniform regions of highly uniform height of segments, and in said bent surface regions formed by bending said segments included in said highly uniform regions in said radial direction of said electrode assembly In the region, the ratio of the stack thickness of the uncoated portion of the bent surface region to the height of the section may be 1.0% to 16.3%.

In yet another embodiment, in the partial area of the bent surface area formed by the uncoated portion of the second electrode, the total stack thickness of the overlapping layers of the uncoated portion is Can be 50μm to 780μm.

In yet another embodiment, the uncoated portion of the second electrode may be divided into a plurality of independently bendable segments, and the second electrode may include highly variable height regions of the segments. and highly uniform regions of highly uniform height of segments, and in said bent surface regions formed by bending said segments included in said highly uniform regions in said radial direction of said electrode assembly In the region, the ratio of the stack thickness of the uncoated portion of the bent surface region to the height of the section may be 0.5% to 13.0%.

In another aspect of the present disclosure, there is also provided an electrode assembly in which a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode are based on The axis is wound to define a core and a periphery, wherein the first electrode includes a first uncoated portion exposed outside the separator at a long side end thereof and along a winding axis direction of the electrode assembly, and A portion of the first uncoated portion is bent along a radial direction of the electrode assembly to form a first bent surface area, and in a local area of the first bent surface area, the first uncoated portion The stack thickness of the coated part is 100 μm to 975 μm.

In one embodiment, the first uncoated portion of the first electrode may be divided into a plurality of sections that can be bent independently, and the first electrode may include a variable height of the sections. highly uniform regions of height uniformity of regions and segments, and in said bent surface regions formed by bending said segments included in said highly uniform regions in said radial direction of said electrode assembly In the area, the ratio of the stack thickness of the uncoated portion of the bent surface area to the height of the section may be 1.0% to 16.3%.

In another embodiment, the second electrode includes a second uncoated portion at a long side end thereof and exposed outside the separator along the winding axis direction of the electrode assembly, and the second electrode A portion of the two uncoated portions is bent along the radial direction of the electrode assembly to form a second bent surface area, and in a partial area of the second bent surface area, the second uncoated portion The stack thickness of the cladding is 50 μm to 780 μm.

In yet another embodiment, the second uncoated portion of the second electrode may be divided into a plurality of sections that can be bent independently, and the second electrode may include sections with variable heights. a highly uniform highly uniform region of varying regions and segments, and the segments in the highly uniform region included in the highly uniform region by bending in the radial direction of the electrode assembly In the formed area, the ratio of the stack thickness of the uncoated portion of the bent surface area to the height of the section may be 0.5% to 13.0%.

In another aspect of the present disclosure, a battery is also provided, the battery including: an electrode assembly, in which a first electrode, a second electrode and a first electrode and a second electrode are inserted between the first electrode and the third electrode. The separator between the two electrodes is wound about an axis to define a core and a periphery, wherein at least one of the first electrode and the second electrode includes a winding at a long side end thereof and along the electrode assembly The uncoated portion is exposed outside the separator in the axial direction, and at least a portion of the uncoated portion is bent along the radial direction of the electrode assembly to form a bent surface area, and on the bent surface In a partial area of the area, the number of stacked layers of the uncoated portion is more than 10; a battery case configured to accommodate the electrode assembly and be electrically connected to the first electrode and the second One of the electrodes has a first polarity; a sealing body configured to seal an open end of the battery case; a terminal electrically connected to the first electrode and the second electrode the other of which has a second polarity and is configured to have a surface exposed to the outside; and a current collector welded to the bent surface area and connected to the battery case and the terminal Either one is electrically connected, wherein the welding area of the current collector overlaps the bent surface area in which the number of stacked layers of the uncoated portion is 10 or more.

In one embodiment, the first electrode may include a first uncoated portion exposed outside the separator at a long side end thereof and along a winding axis direction of the electrode assembly; and when the first electrode The total number of winding turns of an electrode is defined as n ₁ , and the value obtained by dividing the winding turn index k at the k-th winding turn position by the total number of winding turns n ₁ is defined as the winding turn index When the relative radial position R of k _{is 1,k} , based on the relative radial position area in which the first uncoated part is bent, the condition that the number of stacked layers of the first uncoated part is 10 or more is satisfied. The length ratio of the radial regions of R _1,k , where k is a natural number from 1 to n ₁ , may be more than 30%.

In another embodiment, the second electrode may include a second uncoated portion exposed outside the separator at a long side end thereof and along the winding axis direction of the electrode assembly, and when The total number of winding turns of the second electrode is defined as n ₂ , and the value obtained by dividing the winding turn index k at the k-th winding turn position by the total number of winding turns n ₂ is defined as the winding turn index k. When the relative radial position R _2,k of the turn index k is used, based on the relative radial position area in which the second uncoated part is bent, it is satisfied that the number of stacked layers of the second uncoated part is 10 or more The length ratio of the radial zone of the condition R _{2, k} may be more than 30%, where k is a natural number from 1 to n ₂ .

In yet another embodiment, the welding area of the current collector may overlap by more than 50% with the bent surface area in which the number of stacked layers of the uncoated portion is 10 or more.

The welding strength of the welding area of the current collector may be 2kgf/cm ^or more.

Preferably, the welding strength of the welding area of the current collector can be 2kgf/cm ^or more.

Preferably, the welding zones may be spaced apart by a distance of more than 4 mm based on the core center of the electrode assembly and less than 50% of the radius of the electrode assembly.

In another aspect of the present disclosure, a battery is further provided, the battery including: an electrode assembly, in which a first electrode, a second electrode and a first electrode and a second electrode are inserted between the first electrode and the third electrode. The separator between the two electrodes is wound based on the axis to define a core and an outer circumference, wherein the first electrode is included at its long side end and is exposed to the long side end thereof along the winding axis direction of the electrode assembly. a first uncoated portion outside the separator, and a portion of the first uncoated portion is bent along the radial direction of the electrode assembly to form a first bent surface area, and in the first bent In a local area of the folded surface area, the stack thickness of the first uncoated portion is 100 μm to 975 μm; a battery case configured to accommodate the electrode assembly and be electrically connected to the first electrode and One of the second electrodes has a first polarity; a sealing body configured to seal an open end of the battery case; a terminal electrically connected to the first electrode and the the other of the second electrodes having a second polarity and configured to have a surface exposed to the outside; and a first current collector welded to the first bent surface region and connected to the The battery case and any one of the terminals are electrically connected, wherein a stack thickness of the welding area of the first current collector and the first uncoated portion in the first bent surface area is The local areas of 100 μm to 975 μm overlap.

In yet another embodiment, the first uncoated portion of the first electrode may be divided into a plurality of segments that can be bent independently, and the first electrode may include segments with variable heights. a highly uniform highly uniform region of varying regions and segments, and the highly uniform regions included in the highly uniform region by bending in the first bending surface region along the radial direction of the electrode assembly In the area formed by the sections, the ratio of the stack thickness of the uncoated portion of the first bent surface area to the height of the sections may be 1.0% to 16.3%.

Preferably, the welding strength of the first current collector may be in a range of 2kgf/cm ^or above.

In yet another embodiment, the second electrode may include a second uncoated portion at a long side end thereof and exposed outside the separator along the winding axis direction of the electrode assembly, the A portion of the second uncoated portion may be bent along the radial direction of the electrode assembly to form a second bent surface area, and in a local area of the second bent surface area, the second The stack thickness of the uncoated portion may be 50 μm to 780 μm, and the battery may include a second current collector welded to the second bent surface area and connected to the battery case and the terminal. Any one of them is electrically connected, and the welding area of the second current collector may be connected to the local area of the second bending surface area where the stack thickness of the second uncoated portion is 50 μm to 780 μm. overlap.

In yet another embodiment, the second uncoated portion of the second electrode may be divided into a plurality of sections that can be bent independently, and the second electrode may include sections with variable heights. a highly uniform highly uniform region of the variable regions and segments, and the highly uniform regions included in the highly uniform region by bending in the second bending surface region along the radial direction of the electrode assembly In the area formed by the sections, the ratio of the stack thickness of the uncoated portion of the second bent surface area to the height of the sections may be 0.5% to 13.0%.

Preferably, the welding strength of the second current collector may be in a range above 2kgf/ ^cm2 .

In yet another embodiment, the welding area of the first current collector may be connected to the local area of the first bending surface area in which the stacking thickness of the first uncoated portion is 100 μm to 975 μm. Overlap by more than 50%.

In yet another embodiment, the welding area of the second current collector may be connected to the local area of the second bending surface area in which the stacking thickness of the second uncoated portion is 50 μm to 780 μm. Overlap by more than 50%.

In yet another embodiment, the welding area of the first current collector and the welding area of the second current collector may be separated from the welding area based on the electrode assembly in the radial direction of the electrode assembly. The core centers extend at locations approximately the same distance apart.

In yet another embodiment, the extension length of the welding zone of the first current collector may be longer than the extension length of the welding zone of the second current collector.

In another aspect of the present disclosure, a battery pack including the above-mentioned battery and a vehicle including the battery pack are also provided.

beneficial effects

According to one embodiment of the present disclosure, when bending the uncoated portions exposed at both ends of the electrode assembly, it can be achieved by fully ensuring that the uncoated portions overlap into an area of more than 10 layers in the radial direction of the electrode assembly. Prevents the separator or active material layer from being damaged when welding the current collector.

According to yet another embodiment of the present disclosure, since the structure of the uncoated portion adjacent to the core of the electrode assembly is improved, it is possible to prevent the cavity in the core of the electrode assembly from being blocked when the uncoated portion is bent. Therefore, the electrolyte injection process and the process of welding the battery case and the current collector can be easily performed.

According to yet another embodiment of the present disclosure, since the bent surface area of the uncoated portion is directly welded to the current collector instead of the strip-shaped electrode tab, it is possible to provide an electrode assembly with improved energy density and reduced resistance.

According to yet another embodiment of the present disclosure, a cylindrical battery having low internal resistance and improved welding between a current collector and an uncoated portion, and a battery pack and a vehicle including the cylindrical battery can be provided Strength structure.

Furthermore, the present disclosure may have several other effects, and such effects will be described in each embodiment, or any description of related effects that can be easily inferred by those skilled in the art will be omitted.

Description of drawings

The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the foregoing disclosure, help further understand the technical features of the present disclosure, and therefore the present disclosure is not to be construed as being limited to the accompanying drawings.

FIG. 1 is a plan view showing the structure of an electrode used in manufacturing a conventional jointless cylindrical battery;

FIG. 2 is a diagram showing the electrode winding process of a conventional jointless cylindrical battery.

3 is a diagram illustrating a process of welding a current collector to a bent surface area of an uncoated portion in a conventional jointless cylindrical battery.

4 is a plan view showing the structure of an electrode according to one embodiment of the present disclosure.

5 is a diagram illustrating definitions of width, height, and separation pitch of segments according to one embodiment of the present disclosure.

6 is a diagram for explaining overlapping conditions of sections according to one embodiment of the present disclosure.

7a and 7b are views respectively showing an upper cross-sectional structure and a lower cross-sectional structure of the electrode assembly before forming a bent structure of the uncoated portion according to one embodiment of the present disclosure.

8a and 8b are respectively a cross-sectional view and a perspective view illustrating an electrode assembly in which an uncoated portion is bent to form a bent surface region according to one embodiment of the present disclosure.

Figure 9a is a cross-sectional view showing an electrode assembly with a radius of 22 mm included in a cylindrical battery with a form factor of 4680, in which the section of the first electrode is bent from the outer circumference toward the core without being bent in the circumferential direction. When overlapping, the sections overlap in the radial direction to form a bent surface area.

9b is a cross-sectional view showing an electrode assembly with a radius of 22 mm included in a cylindrical battery with a form factor of 4680, in which a section of the first electrode is bent from the outer circumference toward the core while intersecting in the circumferential direction. When folded, the sections overlap in the radial direction and circumferentially to form a bent surface area.

10 is a cross-sectional view showing a cylindrical battery according to one embodiment of the present disclosure, taken along the Y-axis direction.

11 is a cross-sectional view showing a cylindrical battery according to another embodiment of the present disclosure, taken along the Y-axis direction.

12 is a plan view showing the structure of the first current collector according to one embodiment of the present disclosure.

13 is a perspective view showing the structure of a second current collector according to one embodiment of the present disclosure.

14 is a plan view showing a state in which a plurality of cylindrical batteries are electrically connected according to one embodiment of the present disclosure.

FIG. 15 is a partial enlarged plan view illustrating in detail the electrical connections of the plurality of cylindrical batteries of FIG. 14 .

FIG. 16 is a diagram schematically showing a battery pack including a cylindrical battery according to one embodiment of the present disclosure.

17 is a diagram illustrating a vehicle including a battery pack according to one embodiment of the present disclosure.

Detailed ways

Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Before describing, it is to be understood that the terms used in the specification and appended claims should not be construed to be limited to the common and dictionary meanings, but should be based on principles that allow the inventor to appropriately define the terms to obtain the best explanation, based on The corresponding meanings and concepts of the technical aspects of the present disclosure are explained.

Accordingly, the descriptions set forth herein are of preferred embodiments for illustrative purposes only and are not intended to limit the scope of the disclosure, and it is understood that other equivalents may be made to the description without departing from the scope of the disclosure. and variants.

When it is explained that two objects are the same, this means that the objects are "approximately the same". Thus, substantially identical objects may include deviations that are considered low in the art, for example, within 5%. Furthermore, when it is explained that certain parameters are uniform in a predetermined area, this may mean that the parameters are uniform with respect to the average value in the corresponding area.

Although the terms first, second, etc. are used to describe various elements, these elements are not limited by the terms. These terms are used to distinguish one element from another element, in which case a first element may be a second element unless stated to the contrary.

Throughout this specification, unless stated otherwise, each element may be referred to in the singular or the plural.

When an element is "above (or below)" or "on (or under) another element", it can be on the upper surface (or lower surface) of the other element, and Intermediate elements may be present between one element and another element above (or below) the one element.

In addition, when an element is referred to as being "connected," "coupled," or "linked" to another element, it can be directly connected or coupled to the other element, but it is understood that intervening elements may exist between each element. Elements, or each element, may be "connected," "coupled," or "linked" to each other via another element.

Throughout the specification, "A and/or B" means A or B or both A and B, unless expressly stated otherwise, and "C to D" means C or above and D, unless expressly stated otherwise. the following.

For convenience of description, the direction along the length of the winding axis of the electrode assembly wound into a roll shape is referred to herein as the axis direction Y. Furthermore, the direction about the winding axis is referred to herein as the circumferential or peripheral direction X. Furthermore, the direction approaching or away from the winding axis is called the radial direction. Here, in particular, the direction approaching the winding axis is called the centripetal direction, and the direction away from the winding axis is called the centrifugal direction.

First, an electrode assembly according to one embodiment of the present disclosure will be described. The electrode assembly is a core-wound type electrode assembly in which first and second electrodes having a sheet shape and a separator interposed therebetween are wound based on one axis. However, the present invention is not limited to the specific type of electrode assembly, so the electrode assembly may have any wound configuration known in the art.

Preferably, at least one of the first electrode and the second electrode includes an uncoated portion whose long side end in the winding direction is not coated with the active material. At least a portion of the uncoated portion itself serves as an electrode terminal.

4 is a plan view of the structure of electrode 40 according to one embodiment of the present disclosure.

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 may be appropriately selected according to the polarity of the electrode 40 . The active material layer 42 is formed on at least one surface of the current collector 41 and includes an uncoated portion 43 at the long side end in the winding direction X. The uncoated portion 43 is an area where the active material is not coated. The insulating coating layer 44 may be formed at the boundary between the active material layer 42 and the uncoated portion 43 . The insulating coating layer 44 is formed so that at least a portion thereof overlaps the boundary between the active material layer 42 and the uncoated portion 43 . The insulating coating layer 44 may include a polymer resin and may include an inorganic filler such as Al ₂ O ₃ . The area of the uncoated portion 43 in which the insulating coating layer 44 is formed also corresponds to the uncoated portion 43 because the active material layer 42 is not present there.

Preferably, the bent portion of the uncoated portion 43 of the electrode 40 may include a plurality of sections 61 . The plurality of sections 61 may have a height that gradually increases from the core toward the periphery. The area in which the height gradually increases is the remaining area except the uncoated portion (core-side uncoated portion A) adjacent to the core of the electrode assembly. Preferably, the core-side uncoated portion A has a relatively lower height than other portions.

Section 61 may be formed by laser grooving. Section 61 may be formed by known metal foil cutting processes such as ultrasonic cutting or stamping.

When the electrode 40 is rolled, each section 61 may be bent at a bend line 62 in the radial direction of the electrode assembly, for example towards the core. The core refers to the cavity at the center of the winding of the electrode assembly. Each section 61 has a geometry using a bend line 62 as a base. In geometric shapes, the width of its lower part can be greater than the width of its upper part. Furthermore, in the geometry, the width of the lower part may gradually or gradually increase towards the upper part (not shown). Preferably, the geometric shape may have a trapezoidal shape.

In variations, the geometric shape may be formed by connecting one or more straight lines, one or more curves, or a combination thereof. In one embodiment, the geometric shape may be a geometric shape such as a triangle, a rectangle, or a parallelogram. In another embodiment, the geometric shape may have an arcuate shape such as a semicircle, a semiellipse, or the like.

In order to prevent the active material layer 42 and/or the insulating coating layer 44 from being damaged during the bending of the sections 61 , it is preferable that the bottom of the cutting groove between the sections 61 (the part indicated by D4 in FIG. 5 ) is in contact with the active material layer 42 . Predetermined gaps are provided between layers of material 42 . This is because when the uncoated portion 43 is bent, stress is concentrated near the bottom of the cutting groove. The gap is preferably 0.2mm to 4mm. If the gap is adjusted within a corresponding numerical range, the active material layer 42 and/or the insulating coating layer 44 can be prevented from being damaged near the bottom of the cutting groove due to the stress generated during the bending of the section 61 . Furthermore, the gaps prevent the active material layer 42 and/or the insulating coating layer 44 from being damaged due to tolerances during the grooving or cutting of the section 61 .

The plurality of sections 61 may form a plurality of section groups from the core to the periphery. Sections belonging to the same section group can have approximately the same width, height, and separation spacing.

FIG. 5 is a diagram illustrating definitions of width, height, and separation pitch of section 61 according to one embodiment of the present disclosure.

Referring to FIG. 5 , cutting grooves 63 are formed between the sections 61 . The edge of the lower portion of the cutting groove 63 has a rounded shape. That is, the cutting groove 63 includes a substantially flat bottom 63a and a rounded portion 63c. Rounding 63c connects bottom 63a and side 63b of section 61. In a modification, the bottom 63a of the cutting groove 63 may be replaced with a right arc shape. In this case, the side portions 63b of the sections 61 may be smoothly connected by the arcuate shape of the bottom portion 63a.

Preferably, the radius of curvature of the rounded portion 63c may be greater than 0 and less than or equal to 0.5 mm, more preferably, greater than 0 and less than or equal to 0.1 mm. More preferably, the rounded portion 63c may have a radius of curvature of 0.01 mm to 0.05 mm. When the radius of curvature of the rounded portion 63 c satisfies the above numerical range, it is possible to prevent cracks from occurring in the lower portion of the cutting groove 63 when the electrode 40 travels in a winding process or the like.

The width (D1), height (D2) and separation distance (D3) of the section 61 are designed to prevent abnormal deformation of the uncoated portion 43 as much as possible, while sufficiently increasing the number of stacked layers of the uncoated portion 43 to prevent uncoated portions 43 from being deformed. The coated portion 43 is torn during bending and improves the welding strength of the uncoated portion 43 . Abnormal deformation means that the uncoated portion below the bending point does not remain straight, but sinks and deforms irregularly. The bending point may be a point spaced below 2 mm, preferably below 1 mm, from the bottom of the cutting groove 63 (indicated by D4).

The width (D1) of the section 61 is defined as the length between two points where two straight lines extending from the two sides 63b of the section 61 intersect a straight line extending from the bottom 63a of the cutting groove 63. The height of the section 61 is defined as the shortest distance between the uppermost side of the section 61 and a straight line extending from the bottom 63 a of the cutting groove 63 . The separation distance (D3) of the section 61 is defined as the length between two points where a straight line extending from the bottom 63a of the cutting groove 63 intersects a straight line extending from the two sides 63b connected to the bottom 63a. When the side portion 63b and/or the bottom portion 63a is bent, the straight line may be replaced by a tangent line extending from the side portion 63b and/or the bottom portion 63a.

Preferably, the width (D1) of the section 61 can be adjusted in the range of 1 mm to 11 mm. If D1 is less than 1 mm, a non-overlapping area or an empty space (gap) is generated, so that the welding strength cannot be sufficiently ensured when the section 61 is bent toward the core. Meanwhile, if D1 exceeds 11 mm, when the section 61 is bent, the uncoated portion 43 near the bending point (D4) may be torn due to stress. The bending point D4 may be spaced apart from the bottom 63a of the cutting groove 63. The separation distance may be 2 mm or less, preferably 1 mm or less. Furthermore, the height of section 61 can be adjusted in the range of 2 mm to 10 mm. If D2 is less than 2 mm, a non-overlapping area or an empty space (gap) may be generated, so that the welding strength cannot be sufficiently ensured when the section 61 is bent toward the core. Meanwhile, if D2 exceeds 10 mm, it is difficult to manufacture the electrode while uniformly maintaining the flatness of the uncoated portion in the winding direction X. That is, an excessive height of the uncoated portion causes a warped surface in the uncoated portion. Furthermore, the separation distance (D3) of the sections 61 can be adjusted in the range of 0.05 mm to 1 mm. If D3 is less than 0.05 mm, cracks may occur at the uncoated portion 43 near the bottom of the cutting groove 63 due to stress when the electrode 40 travels in a winding process or the like. Meanwhile, if D3 exceeds 1 mm, a non-overlapping area or an empty space (gap) in which the sections 61 do not overlap each other may be generated, so that the welding strength cannot be sufficiently ensured when the sections 61 are bent.

Meanwhile, when the current collector 41 of the electrode 40 is made of aluminum, it is more preferable to set the separation distance D3 to 0.5 mm or more. When D3 is 0.5 mm or more, even if the electrode 40 travels at a speed of 100 mm/sec or more under a pulling force of 300 gf or more during the winding process or the like, cracks can be prevented from occurring in the lower part of the cutting groove 63 .

According to the experimental results, when the current collector 41 of the electrode 40 is an aluminum foil with a thickness of 15 μm and D3 of 0.5 mm or more, when the electrode 40 travels under the above traveling conditions, no cracks will occur in the lower part of the cutting groove 63.

Referring again to FIG. 4 , the width (d _A ) of the core side uncoated portion A is designed by applying the following condition: when the section 61 is bent toward the core, more than 90% of the core of the electrode assembly is not core side uncoated. Part A covered.

In one embodiment, the width (d _A ) of the core-side uncoated portion A may be increased in proportion to the bend length of section 61 of group 1 . The bending length corresponds to the height of the section 61 based on the bending line 62 (Fig. 4).

In a specific embodiment, when the electrode 40 is used to manufacture an electrode assembly of a cylindrical battery with a shape factor of 4680, the width (d _A ) of the uncoated portion A on the core side can be set according to the diameter of the core of the electrode assembly. is 180mm to 350mm.

Preferably, the ratio d _A /L _e of the width (d _A ) of the core side uncoated portion (A) to the long side length (L _e ) of the electrode 40 may be 1% to 30%. In a large cylindrical battery with a diameter of 46 mm, the length of the electrode 40 is quite long (from 3000 mm to 5000 mm), so the core side uncoated part (A) can be designed to be long enough. In cylindrical cells with form factor 1865 or 2170, the electrode length ranges from 600mm to 1200mm. In a typical cylindrical battery, it is difficult to design the ratio d _A /L _e within the above numerical range.

In one embodiment, the width of each segment group may be designed to constitute the same winding turn of the electrode assembly.

In another embodiment, the width of each segment group may be designed to constitute multiple turns of the electrode assembly.

In a variant, the width and/or height and/or separation spacing of sections 61 belonging to the same section group can increase or decrease gradually and/or stepwise and/or irregularly within or between groups. .

Group 1 to Group 7 are only one example of section groups. The number of groups and the number of sections 61 included in each group can be adjusted to distribute the stress as much as possible during the bending process of the uncoated portion 43 to fully ensure the welding strength and minimize the side portions of the sections 61 63b and allows the sections 61 to overlap into multiple layers in the radial direction of the electrode assembly without interfering with each other.

In a variant, some groups of sections may be removed. In this case, the height of the uncoated portion in the area where the section is removed may be the same as the height of the core-side uncoated portion A.

Preferably, the electrode 40 can be divided into a highly variable region and a highly uniform region. In the highly variable region, the height of the section 61 changes along the long side direction, and in the highly uniform region, the height of the section 61 is uniform.

In the electrode 40 , the highly variable region is a region corresponding to Group 1 to Group 7 , and the highly uniform region is a region located near the outer periphery other than Group 7 .

In a specific embodiment, the width (d _A ) of the uncoated portion A on the core side may be 180 mm to 350 mm. The width of Group 1 may be 35% to 55% of the width of the core-side uncoated portion A. The width of Group 2 may be 120% to 150% of the width of Group 1. The width of group 3 may be 110% to 135% of the width of group 2. The width of group 4 may be 75% to 90% of the width of group 3. The width of group 5 may be 120% to 150% of the width of group 4. The width of group 6 may be 100% to 120% of the width of group 5. The width of group 7 may be 90% to 120% of the width of group 6.

The reason why the widths of Group 1 to Group 7 do not show a constant increasing or decreasing pattern is that the segment width gradually increases from Group 1 to Group 7, but the number of segments included in a group is limited to an integer, and the electrode 40 The thickness has deviation along the winding direction X. Therefore, the number of segments in a specific segment group may be reduced. Therefore, from the core to the periphery, the width of the group may show an irregular changing pattern as in the above embodiments.

Assuming that the widths in the winding direction of each of the three segment groups that are continuously adjacent to each other in the circumferential direction of the electrode assembly are W1, W2, and W3 respectively, it can be included that W3/W2 is smaller than W2/W1 A combination of segment groups.

In a specific embodiment, groups 4 to 6 correspond to this situation. 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%.

Preferably, in the plurality of sections 61, the lower internal angle (θ) may increase from the core to the periphery. The lower internal angle (θ) corresponds to the angle between a straight line passing through the bend line 62 ( FIG. 4 ) and a straight line (or tangent) extending from the side 63 b of the section 61 . When the section 61 is asymmetrical in the left-right direction, the left inner corner and the right inner corner may be different from each other.

As the radius of the electrode assembly increases, the radius of curvature increases. If the lower inner angle (θ) of the section 61 increases as the radius of the electrode assembly increases, the stress generated in the radial and circumferential directions when the section 61 is bent can be alleviated. In addition, when the lower inner angle (θ) increases, when the section 61 is bent, the area of overlap between the inside and the section 61 and the number of stacked layers of the section 61 also increase, thereby ensuring that the radial and circumferential Uniform weld strength and flatten the bend surface area.

Preferably, if the angle of the lower inner angle (θ) is adjusted as the radius of the electrode assembly increases, the sections 61 may overlap in the circumferential direction as well as the radial direction of the electrode assembly when the sections 61 are bent.

(a) and (b) of FIG. 6 show an embodiment in which the sides of the section 61 bent toward the core of the electrode assembly are spaced parallel in any winding turn of radius r based on the core center and in which Embodiment in which the sides of the bent sections 61 intersect each other.

Referring to FIG. 6 , a pair of sections 61 adjacent to each other are provided in a winding turn with a radius r relative to the core center O of the electrode assembly. Adjacent sections 61 have approximately the same width and height.

In (a) of FIG. 6 , the lower inner angle θ is _assumed to be an angle assuming that the sides of the section 61 are substantially parallel. The lower internal angle θ _assumed is an angle that can be uniquely determined by the arc length L _arc corresponding to the lower part of the section 61 . Meanwhile, θ _real is the actual lower internal angle when the sides of adjacent sections 61 intersect each other.

Preferably, when the lower inner angles θ _assumption and θ _real satisfy the following formula 1, the sections 61 provided in the winding turns located at the radius r with respect to the core center O may 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 in which the section 61 is provided based on the core center of the electrode assembly.

L _arc is the length of the arc (solid line) corresponding to the lower part of the segment (dashed line) in a circle of radius r, and is uniquely determined from the width (D1) of segment 61.

'360°*(L _arc /2πr)' is the circumferential angle α of the lower part of section 61 (dashed line).

'360°*(L _arc /2πr)*0.5' is the angle between line segment OB and line segment OA in right triangle OAB.

'90°-360°*(L _arc /2πr)*0.5' is the angle between the line segment OA and the line segment AB in the right triangle OAB, which approximately corresponds to the lower interior angle (θ _assumption ) of the segment 61.

Preferably, the circumferential angle α of L _arc at any winding turn radius r may be less than or equal to 45°. If the circumferential angle α exceeds 45°, the section 61 is not easily bent. Therefore, at any radius r, L _arc is larger than 1mm (which is the lower limit of D1) and has a length below (45/360)*(2πr).

The circumferential angle α can be varied depending on the radius (r) of the winding turn in which the section 61 is located. In one aspect, the circumferential angle α of the section 61 may gradually or gradually increase in the radial direction of the electrode assembly within the above numerical range, or vice versa. In another aspect, the circumferential angle α of the section 61 may gradually increase or decrease in the radial direction of the electrode assembly within the above numerical range, and then gradually increase or decrease, or vice versa. On the other hand, the circumferential angle α of the section 61 may be substantially the same along the radial direction of the electrode assembly within the above numerical range.

Preferably, when the width of each of the plurality of sections 61 is changed along the winding direction, the circumferential angle α may be in a range of 45 degrees or less, and the width of each of the plurality of sections 61 Can be in the range of 1mm to 11mm.

In one embodiment, when r is 20 mm and the circumferential angle α is 30°, L _arc is 10.5 mm and θ _assumes approximately 75 degrees. As another example, if r is 25mm and the circumferential angle α is 25°, L _arc is 10.9mm and θ _assumes approximately 77.5 degrees.

Preferably, at any winding turn radius r, (θ _real /θ _assumption -1) may be defined as the overlap ratio of the segments 61 in the circumferential direction. The overlap ratio of the sections 61 is preferably greater than 0 and equal to or less than 0.05. The θ _assumption is the angle uniquely determined by the arc L _arc at the winding turn radius r. If the overlap ratio of the sections 61 is greater than 0.05, the sides of the sections 61 may interfere with each other when the sections 61 are bent, and therefore the sections 61 may not be easily bent.

The degree of overlap of sections 61 increases in proportion to the overlap ratio. If the sections 61 overlap each other in the circumferential direction of the winding turns, the number of stacked layers of the sections 61 can be further increased when the sections 61 are bent. Embodiments regarding this will be described later.

Preferably, when the electrode 40 is used to make an electrode assembly of a cylindrical battery with a form factor of 4680, the radius of the core is 4 mm, and the height of the section closest to the core is 3 mm, when the radius of the electrode assembly increases from 7 mm to At 22 mm, the lower inner angle of the section 61 can gradually increase in the range of 60° to 85°.

The radius range and the lower inner angle range may be determined based on the shape factor and design specifications regarding the diameter of the core, the height of the section closest to the core, the width of section 61 (D1), and the overlap ratio.

At the same time, the overlapping conditions of the sections can be changed as follows. That is, when a virtual circle passing through a pair of sections 61 adjacent to each other based on the core center O of the electrode assembly 40 is drawn as shown in (b) of FIG. 6 , if an arc passing through each section 61 If e ₁ -e ₂ and arcs e ₃ -e ₄ overlap each other, then the adjacent pair of segments may overlap each other. The overlap ratio of the section 61 may be defined as the ratio of the length of the overlapping arc e ₂ -e ₃ to the length of the arc e ₁ -e ₂ (or e ₃ -e ₄ ) when drawing multiple virtual circles with different radii the maximum value. The overlap ratio of the section 61 may be greater than 0 and equal to or less than 0.05.

The shape of section 60 may change differently depending on location. In one embodiment, rounded shapes that are beneficial to stress distribution (eg, semicircles, semiellipses, etc.) are applied to areas where stress is concentrated, and polygonal shapes with the largest area (eg, rectangles, trapezoids, parallelograms, etc.) Can be applied to areas with relatively low stress.

The segment structure can also be applied to the core-side uncoated portion A. However, if the segment structure is applied to the core-side uncoated portion A, when the segments are bent according to the curvature radius of the core, the end of the core-side uncoated portion A may be bent toward the outer circumference, which is called reverse Towards forming. Therefore, the core-side uncoated portion A does not have segments, or even if the segment structure is applied to the core-side uncoated portion A, it is desirable to control the width and/or height and/or the width and/or height of the segments 61 in consideration of the curvature radius of the core. or separation spacing so that reverse forming does not occur.

The electrode structure of the above embodiment (modification) can be applied to the first electrode and/or the second electrode having different polarities included in the core-wound electrode assembly. Furthermore, when the electrode structure of the above embodiment (modification) is applied to any one of the first electrode and the second electrode, a conventional electrode structure may be applied to the other. Furthermore, the electrode structures applied to the first electrode and the second electrode may not be the same but may be different from each other.

For example, when the first electrode and the second electrode are the positive electrode and the negative electrode respectively, any one of the above embodiments (modifications) is applied to the first electrode, and a conventional electrode structure may be applied to the second electrode (see FIG. 1 ) .

As another example, when the first electrode and the second electrode are the positive electrode and the negative electrode respectively, any one of the above embodiments (modifications) may be selectively applied to the first electrode, and may be selected to the second electrode. Any one of the above embodiments (modifications) is applicable.

In the present disclosure, the positive active material coated on the positive electrode and the negative active material coated on the negative electrode may adopt any active material known in the art without limitation.

In one embodiment, the cathode active material may include an alkali metal compound represented by the general formula A[A _{x My} ]O _2+z (A includes at least one of Li, Na, and K; M includes Ni, At least one element of Co, Mn, Ca, Mg, Al, Ti, Si, Fe, Mo, V, Zr, Zn, Cu, Al, Mo, Sc, Zr, Ru and Cr; x≥0, 1≤x +y≤2, -0.1≤z≤2; and the stoichiometric coefficients of x, y, and z are selected to maintain the electroneutrality of the compound).

In another embodiment, the cathode active material may be an alkali metal compound xLiM ¹ O ₂ -(1-x)Li ₂ M ² O ₃ (M ¹ includes at least one average Elements with an oxidation state of 3; ^M2 includes at least one element with an average oxidation state of 4; and 0≤x≤1).

In yet another embodiment, the cathode active material may be formed by the general formula Li _a M ¹ _x Fe _1-x M ² _y P _1-y M ³ _z O _4-z (M ¹ includes selected from Ti, Si, Mn, At least one element of Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg and Al; ^M2 includes selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, At least one element of Al, Mg, Al, As, Sb, Si, Ge, V and S; ^M3 includes a halogen element optionally including F; 0<a≤2, 0≤x≤1, 0≤y <1, 0≤z<1; select the stoichiometric coefficients of a, x, y, z to maintain the electrical neutrality of the compound) or Li ₃ M ₂ (PO ₄ ) ₃ (M includes selected from Ti, Si, Mn , Fe, Co, V, Cr, Mo, Ni, Al, Mg and at least one element of Al) lithium metal phosphate represented.

Preferably, the positive active material may include primary particles and/or secondary particles in which primary particles are aggregated together.

In one embodiment, the negative active material may be carbon material, lithium metal or lithium metal compound, silicon or silicon compound, tin or tin compound, etc. Metal oxides with potentials less than 2V (such as TiO ₂ and SnO ₂ ) can also be used as negative electrode active materials. As the carbon material, low crystalline carbon, high crystalline carbon, etc. can be used.

The separator may be a porous polymer film, for example, a porous polymer film made from a polyolefin-based polymer such as ethylene homopolymer, propylene homopolymer, ethylene/butylene copolymer, ethylene/hexane Ethylene copolymer, ethylene/methacrylate copolymer, etc. or laminates thereof. As another example, the separator can be made of ordinary porous non-woven fabric, for example, non-woven fabric made of glass fiber, polyethylene terephthalate fiber, etc. with a high melting point.

The separator may include a coating of inorganic particles in at least one surface thereof. It is also possible that the membrane itself is made of a coating of inorganic particles. Particles in the coating layer may be coupled with a binder so that interparticle volumes exist between adjacent particles.

The inorganic particles can be made of inorganic materials with a dielectric constant of 5 or more. In one non-limiting example, the inorganic particles may include at least one material selected from the group consisting of: Pb(Zr,Ti)O ₃ (PZT), Pb _{1- x} La _x Zr _1-y Ti _y O ₃ (PLZT), PB (Mg ₃ Nb _2/3 )O ₃ -PbTiO ₃ (PMN-PT), BaTiO ₃ , hafnium oxide (HfO ₂ ), SrTiO ₃ , TiO ₂ , Al ₂ O ₃ , ZrO ₂ , SnO ₂ , CeO ₂ , MgO, CaO, ZnO and Y ₂ O ₃ .

The electrode assembly according to the present embodiment is a core-wound electrode assembly 80 in which the electrode 40 of 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 type of electrode assembly.

7a and 7b are respectively views showing an upper cross-sectional structure and a lower cross-sectional structure of the electrode assembly 80 before forming the bent structure of the uncoated portions 43a, 43a' according to one embodiment of the present disclosure. 8a and 8b are respectively a cross-sectional view and a perspective view illustrating the electrode assembly 80 having the bent surface area F formed when the uncoated portions 43a, 43a' are bent according to one embodiment of the present disclosure.

The electrode assembly 80 may be manufactured by means of the winding method described with reference to FIG. 2 . For convenience of description, the protruding structures of the uncoated portions 43a, 43a' extending outside the separator are shown in detail, and the winding structure of the separator is not drawn. The upwardly protruding uncoated portion 43 a of the electrode assembly 80 extends from the first electrode 40 . The downwardly protruding uncoated portion 43a' of the electrode assembly 80 extends from the second electrode 40'. The end of the septum is marked by a dotted line.

A pattern of varying heights of uncoated portions 43a, 43a' is schematically shown. That is, the height of the uncoated portions 43a, 43a' may be irregularly changed depending on the position of the cut section. For example, when the side portion of the section 61 having a trapezoidal shape is cut, the height of the uncoated portion in the cross-section is lower than the height of the section 61 (D2 in FIG. 4). Furthermore, the uncoated portions 43a, 43a' are not shown at the point where the cutting groove 63 (Fig. 5) is cut.

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

Referring to Figures 7a, 7b, 8a and 8b, the uncoated portion 43a of the first electrode 40 and the uncoated portion 43a' of the second electrode 40' are bent in the radial direction to form the bent surface area F.

In the winding structure of the first electrode 40 , assuming that the total number of winding turns of the first electrode 40 is n ₁ , when the winding index k (a natural number from 1 to n ₁ ) of the kth winding turn is divided by the total The value obtained by the winding turn number n ₁ is defined as the relative radial position R _1,k region of the k-th winding turn in which the number of stacked layers of the uncoated portion 43a is 10 or more _. The ratio of the radial length to the radial length of the winding turns including the segments is more than 30%.

For reference, the relative radial position of the 1st winding turn is 1/n ₁ since the winding turn index is 1. The relative radial position of the k-th winding turn is k/n ₁ . The relative radial position of the final n _1th winding turn is 1. That is, the relative radial position increases from 1/n ₁ to 1 from the core of the electrode assembly 80 to its outer circumference.

In the winding structure of the second electrode 40', assuming that the total number of winding turns of the second electrode 40' is n ₂ , when the winding index k (a natural number from 1 to n ₂ ) of the kth winding turn is divided The value obtained with the total number of winding turns n ₂ is defined as the relative radial position R _{2,k of} the kth winding turn when the number of stacked layers of the uncoated portion is 10 or more The ratio of the radial length of the area to the radial length of the winding turns in which the segments are provided is more than 30%.

For reference, the relative radial position of the 1st winding turn is 1/n ₂ since the winding turn index is 1. The relative radial position of the k-th winding turn is k/n ₂ . The relative radial position of the final n _2nd winding turn is 1. That is, the relative radial position increases from 1/n ₂ to 1 from the core of the electrode assembly 80 to its outer circumference.

Preferably, the winding turn index k of the first electrode 40 and the second electrode 40' is understood to be a variable that can be assigned different values.

When the uncoated portions 43a, 43a' are bent in the radial direction, the bent surface areas F are formed on the upper and lower portions of the electrode assembly 80, as shown in Figures 8a and 8b.

Referring to FIGS. 8 a and 8 b , the plurality of sections 61 are overlapped into a plurality of layers in the radial direction while being bent toward the core C of the electrode assembly 80 .

The number of stacked layers of segments 61 may be defined as the number of segments 61 that intersect an imaginary line when an imaginary line is drawn along the winding axis direction (Y) at any radial point on the bending surface region F.

Preferably, the number of stacked layers of the section 61 may be more than 10 in a radius area based on at least 30% of the radial length (R ₁ ) of the winding turns including the section 61 in order to sufficiently increase the bending surface area The welding strength between F and the current collector, and prevents the separator and active material layer from being damaged during the welding process.

The current collector may be laser welded to the bent surface area F of the uncoated portion 43a, 43a&apos;. Alternatively, other known welding techniques such as resistance welding may be used. When applying laser welding, it is expected to increase the laser power to fully ensure the welding strength. If the laser power is increased, the laser light may penetrate the overlapping region of the uncoated portions 43a, 43a' into the electrode assembly 80, which may damage the separator and active material layer. Therefore, in order to prevent laser penetration, it is preferable to increase the number of stacked layers of the uncoated portions 43a, 43a' in the welding area above a certain level. In order to increase the number of stacked layers of the uncoated portions 43a, 43a', the height of the section 61 must be increased. However, if the height of the section 61 is increased, the uncoated portions 43a, 43a' may warp during the manufacturing process of the electrode 40. Therefore, it is desirable to adjust the height of section 61 to an appropriate level, preferably 2 mm to 10 mm.

If compared with R ₁ in the bending surface area F, the radius area where the number of stacked layers of the section 61 is more than 10 is designed to be more than 30%, and the area where the section 61 overlaps into more than 10 layers is lasered Welded to the current collector, even if the power of the laser is increased, the overlap of the uncoated portion sufficiently shields the laser to prevent the separator and active material layer from being damaged by the laser. In addition, since the number of stacked layers of the section 61 is larger in the laser-irradiated area, a weld bead with sufficient volume and thickness is formed. Therefore, the welding strength can be fully ensured, and the resistance of the welding interface can also be reduced.

When welding the current collector, the laser power can be determined by the desired welding strength between the bent surface area F and the current collector. The welding strength increases in proportion to the number of stacked layers of the uncoated portions 43a, 43a'. This is because as the number of stacked layers of the uncoated portions 43a, 43a' increases, the volume of the weld bead formed by the laser increases.

Preferably, the welding strength may be 2 kgf/cm ² or more, and more preferably 4 kgf/cm ² or more. If the welding strength satisfies the above numerical range, even if severe vibration is applied to the electrode assembly 80 in the winding axis direction and/or the radial direction, the characteristics of the welding interface will not be deteriorated, and the volume of the welding bead is sufficient to reduce the welding interface The resistance. The power of the laser used to achieve the above welding intensity conditions changes according to the laser equipment, and can be appropriately adjusted within the range of 250W to 320W or 40% to 100% of the maximum laser power specification.

The welding strength can be defined as the tensile force per unit area (kgf/cm ² ) of the current collector when the current collector begins to separate from the bent surface area F. Specifically, after the welding of the current collector is completed, a pulling force is applied to the current collector, but the magnitude of the pulling force gradually increases. As the pulling force increases, the uncoated portions 43a, 43a' begin to separate from the welding interface. At this time, the value obtained by dividing the tensile force applied to the current collector by the area of the current collector is the welding strength.

Preferably, the first electrode 40 may include a current collector (foil) 41 and an active material coating layer 42 formed on at least one surface of the current collector 41 . Here, the current collector 41 may have a thickness of 10 μm to 25 μm, and an interval between adjacent winding turns in the radial direction of the electrode assembly 80 may be 200 μm to 500 μm. The current collector 41 may be made of aluminum.

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

Referring to Figures 4, 7a and 7b, in the winding structure of the first electrode 40, from the relative radial position R _1,1 of the first electrode 40 to the preset first relative radial position R _1,k* The height of the uncoated portion of the region may be less than the height of the uncoated portion of the region from the relative radial position R _1,k*+1 of the k*+1th winding turn to the relative radial position 1 . The height of the uncoated portion of the area from the relative radial position R _1,1 to the preset first relative radial position R _1,k* corresponds to the height of the uncoated portion of the core-side uncoated portion A ( See Figure 4).

In the wound structure of the first electrode 40 , if there are winding turns at the outer circumference that do not include the section 61 , the relative radial position 1 may correspond to the relative radial position of the outermost winding turn including the section 61 .

Preferably, in the wound structure of the first electrode 40, the height of the uncoated portion in the area from the relative radial position R _1,1 to the first relative radial position R _1,k* may be smaller than that obtained by overlapping bends. The height of the folded surface area F formed by the folded uncoated portion.

Preferably, in the wound structure of the first electrode 40 , the uncoated portion of the area from the relative radial position R _1,1 to the first relative radial position R _1,k* may not face the core of the electrode assembly 80 Bend.

Similar to the first electrode 40, in the wound structure of the second electrode 40', the uncoated portion of the area from the relative radial position R _2,1 to the preset first relative radial position R _2,k* The height of may be less than the height of the uncoated portion of the area from the relative radial position R _2,k*+1 of the k*+1th winding turn to the relative radial position 1.

In the wound structure of the second electrode 40 ′, if there are winding turns at the outer circumference that do not include the section 61 , the relative radial position 1 may correspond to the relative radial position of the outermost winding turn including the section 61 .

Furthermore, in the area from the relative radial position R _2,1 to the preset first relative radial position R _2,k* , the height of the uncoated portion may be smaller than that formed by overlapping and bending the uncoated portion The height of the bending surface area F.

Preferably, the uncoated portion of the area from the relative radial position R _2,1 to the first relative radial position R _2,k* may not be bent toward the core of the electrode assembly.

Preferably, in the wound structure of the second electrode 40', the height of the uncoated portion in the area from the relative radial position R _2,1 to the first relative radial position R _2,k* may be smaller than the height from the relative radial position R 2,k* to the first relative radial position R 2,k*. Toward position R _2,k*+1 to the height of the uncoated portion of the area relative to radial position 1, and may not be bent toward the core.

In the wound structure of the first electrode 40 , the bending length fd _1,k*+1 of the uncoated portion relative to the radial position R _{1,k*+1 may be shorter than the bending length fd 1,k*+1} from the relative radial position R _1,1 Radial length to relative radial position R _1,k* . Therefore, the core C of the electrode assembly 80 may not be blocked by the bent portion of the uncoated portion 43 a located in the area from the relative radial position R _1,k*+1 to the relative radial position 1 .

Alternatively, more than 90% of the core C of the electrode assembly 80 based on its radius ( _rc ) may not be covered by uncoated elements located in a region from the relative radial position R _1,k*+1 to the relative radial position 1 The bent portion of the covering portion 43a blocks. That is, a radial area corresponding to at least 0 to 0.9rc of the core _C may not be blocked by the bent portion of the uncoated portion 43a.

Preferably, the bending length fd 1 _{,k*+1 of the uncoated portion 43a located at the relative radial position R 1 ,k*+1} , the radius ( _rc ) of the core, and the relative diameter from the center of the core C to the relative diameter The distance (d _{1,k*+1) to the position R 1 ,k*+1} can satisfy the following formula 2.

<Formula 2>

fd _1,k*+1 +0.9*r _c ≤d _1,k*+1

Preferably, in the wound structure of the second electrode 40', the height of the uncoated portion in the area from the relative radial position R _2,1 to the first relative radial position R _2,k* may be smaller than the height from the relative radial position R 2,k* to the first relative radial position R 2,k*. Toward position R _2,k*+1 to the height of the uncoated portion of the area relative to radial position 1, and may not be bent toward the core.

In the wound structure of the second electrode 40', the bending length fd _2,k*+1 of the uncoated portion located at the relative radial position R 2 _,k*+1 may be shorter than that from the relative radial position R _{2 ,1} to the length of the first relative radial position R _2,k* . Therefore, the core C of the electrode assembly 80 may not be blocked by the bent portion of the uncoated portion located in the area from the relative radial position R _2,k*+1 to the relative radial position 1 .

Alternatively, more than 90% of the core C of the electrode assembly 80 based on its radius ( _rc ) may not be blocked by the bent portion of the uncoated portion 43a' located at the relative radial position R _2,k*+1 .

Preferably, the bending length fd _{2,k*+1 of the uncoated portion 43a' located at the relative radial position R 2 ,k*+1} , the radius ( _rc ) of the core, and the angle from the center of the core C to the relative The distance (d _2,k*+1 ) from the radial position R 2 _,k*+1 can satisfy the following formula 3.

<Formula 3>

fd _2,k*+1 +0.9*r _c ≤d _2,k*+1

Preferably, in the winding structure of the first electrode 40, the second relative radial position R1,k@+1 of the second electrode 40' is from the preset k@+1th winding turn to the relative radial position R1 _,k@+1. The uncoated portion of position 1 is divided into a plurality of sections 61 , and the heights of the plurality of sections 61 may be substantially the same from the relative radial position R _1,k@+1 to the relative radial position 1 .

At the same time, in the winding structure of the first electrode 40, the remaining area from the relative radial position R _1,k*+1 to the preset second relative radial position R _1,k@ of the kth winding turn The coating part 43a is divided into a plurality of sections 61, the height of which may be gradually or gradually increased toward the outer circumference. Therefore, the area from the relative radial position R _1,k*+1 to the relative radial position R _1,k@ corresponds to the highly variable region.

For example, in the winding structure of the first electrode 40 with a radius of 22 mm, when the radial length of the highly variable region of the segment is defined as H ₁ and H ₁ is the same as the winding structure of the first electrode 40 except the core C When the ratio of the radii of the structure (Rr _c ) is defined as the highly variable region ratio (H ₁ /(Rr _c )), the ratio of the highly variable region can be calculated as follows by rounding to zero decimal places.

In Embodiment 1, R may be 22 mm, the core radius ( _rc ) may be 5 mm, and _Rrc may be 17 mm. The height of the section 61 can vary from 2 mm to 10 mm in 8 steps in a radius zone of 7 mm to 15 mm. After a radius of 15 mm, the height of section 61 remains at 10 mm. Since H ₁ is 8mm, the height variable area ratio can be 47% (8mm/17mm).

In Example 2, R and r _c are the same as in Example 1. The height of the section 61 can vary from 2 mm to 9 mm in 7 steps in a radius zone of 7 mm to 14 mm. After a radius of 14 mm, the height of section 61 remains at 9 mm. Since H ₁ is 7mm, the height variable area ratio can be 41% (7mm/17mm).

In Example 3, R and r _c are the same as in Example 1. The height of the section 61 can be varied in 6 steps from 2 to 8 mm in a radius zone of 7 to 13 mm. After a radius of 13 mm, the height of section 61 remains at 8 mm. Since H ₁ is 6mm, the height variable area ratio can be 35% (6mm/17mm).

In Example 4, R and r _c are the same as in Example 1. The height of the section 61 can be varied in 5 steps from 2 mm to 7 mm in a radius zone of 7 mm to 12 mm. After a radius of 12 mm, the height of section 61 remains at 7 mm. Since H ₁ is 5mm, the height variable area ratio can be 29% (5mm/17mm).

In Example 5, R and r _c are the same as in Example 1. The height of the section 61 can vary from 2 mm to 6 mm in 4 steps in a radius zone of 7 mm to 11 mm. After a radius of 11 mm, the height of section 61 remains at 6 mm. Since H ₁ is 4mm, the height variable area ratio can be 24% (4mm/17mm).

In Example 6, R and r _c are the same as in Example 1. The height of the section 61 can be varied in 3 steps from 2 mm to 5 mm in a radius zone of 7 mm to 10 mm. After a radius of 10 mm, the height of section 61 remains at 5 mm. Since H ₁ is 3mm, the height variable area ratio can be 18% (3mm/17mm).

In Example 7, R and r _c are the same as in Example 1. The height of the section 61 can be varied in 2 steps from 2 mm to 4 mm in a radius zone of 7 mm to 9 mm. After a radius of 9 mm, the height of section 61 remains at 4 mm. Since H ₁ is 2mm, the height variable area ratio can be 12% (2mm/17mm).

In Example 8, R and r _c are the same as in Example 1. The height of the section 61 can be varied in 1 step from 2 mm to 3 mm in a radius zone of 7 mm to 8 mm. After a radius of 8 mm, the height of section 61 remains at 3 mm. Since _H1 is 1mm, the height variable area ratio can be 6% (1mm/17mm).

To sum up, when R is 22mm and r _c is 5mm, if the height of the section in the radius area of 7mm to 15mm changes in the range of 2mm to 10mm in any of 1 to 8 steps, Then the highly variable area ratio may be 6% to 47%.

The numerical range of the highly variable zone ratio may vary depending on the size of the radius ( _rc ) of the core C. Since the calculation method is similar to above, only the results are disclosed.

In one embodiment, when R is 22 mm and r _c is 4 mm, if the height of the section in the radius zone of 6 mm to 14 mm is stepped in the range of 2 mm to 10 mm in any of 1 to 8 steps change, the highly variable area ratio can be 6% to 44%.

In another embodiment, when R is 22 mm and r _c is 3 mm, if the height of the section in the radius zone of 5 mm to 13 mm is in the range of 2 mm to 10 mm in any of 1 to 8 steps Changing step by step, the highly variable zone ratio can be from 5% to 42%.

In yet another embodiment, when R is 22 mm and r _c is 2 mm, if the height of the section in the radius zone of 4 mm to 12 mm is in the range of 2 mm to 10 mm in any of 1 to 8 steps Changing step by step, the highly variable zone ratio can be from 5% to 40%.

According to the above calculation example, when the radius (r _c ) of the core C changes within the range of 2 mm to 5 mm, the height variable area ratio is 5% to 47%. When the radius of the electrode assembly 80 is constant, the lower limit and the upper limit of the highly variable region ratio decrease accordingly as the radius ( _rc ) of the core C decreases.

Meanwhile, the upper and lower limits of the height variable area ratio can be changed according to the amount of height change and the amount of height change of the section 61 for every 1 mm increase in radius.

In one embodiment, when the height of the section 61 changes by 0.2 mm for every 1 mm increase in radius, the lower and upper limits of the height variable zone ratio are 1% and 9%, respectively.

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

According to the above embodiment, the highly variable region ratio is preferably 1% to 56%. If the height variable area ratio of the section 61 satisfies the above numerical range, the ratio of the relative radial positions in which the number of stacked layers of the uncoated portion 40 is 10 or more can be at least the radial direction of the winding turns of the section 61 30% of length (R ₁ ). As will be described later, this configuration provides useful effects in terms of weld strength and electrical resistance of the current collector.

Referring again to Figures 4 and 7b, in the winding structure of the second electrode 40', from the relative radial position R2 _,k*+1 to the second relative radial position R of the preset k@th winding turn The uncoated portion of the area of _2,k@ is also divided into a plurality of sections 61, and the heights of the plurality of sections 61 may gradually or gradually increase toward the outer circumference. Therefore, the area from the relative radial position R _2,k*+1 to the relative radial position R _2,k@ corresponds to the highly variable region.

In the wound structure of the second electrode 40', when the radial length of the highly variable region _is defined as H2 and _H2 is the same as the radius ( _Rrc ) of the wound structure of the second electrode 40' except the core C When the ratio of is defined as the highly variable region ratio (H ₂ /(Rr _c )), the ratio of the highly variable region is preferably 1% to 56%, similar to the first electrode.

If the height variable area ratio of the section 61 of the uncoated section 43a' satisfies the above numerical range, then compared with the radial length ( _R2 ) of the winding turns including the section 61, where the uncoated section 43a' When the number of stacked layers is 10 or more, the ratio of the radial length to the relative radial position may be at least 30%.

In the winding structure of the second electrode 40', the second electrode 40' goes from the second relative radial position R2 _{,k@+1 of the preset k@+1th} winding turn to the relative radial position 1 The uncoated portion is divided into a plurality of sections 61, and the heights of the plurality of sections 61 may be substantially the same from the relative radial position R2 _,k@+1 to the relative radial position 1.

Preferably, in the winding structure of the first electrode 40 , the uncoated portion 43 a bent toward the core is divided into a plurality of sections 61 , and the heights of the plurality of sections 61 in the winding axis direction and the winding direction At least one of the widths on may increase gradually or stepwise from the core toward the periphery, individually or in groups.

Similarly, in the wound structure of the second electrode 40', the uncoated portion 43a' bent toward the core is divided into a plurality of sections 61, and the heights and rolls of the plurality of sections 61 in the winding axis direction are At least one of the widths in the circumferential direction may increase gradually or stepwise from the core toward the periphery, individually or in groups.

Preferably, when the bent portions of the uncoated portions 43a, 43a' are divided into a plurality of sections 61, each of the plurality of sections 61 can satisfy at least one of the following conditions: in the winding direction The width of 1mm to 11mm (D1 in Figure 5) conditions; the height of 2mm to 10mm in the winding axis direction (D2 in Figure 5) conditions; and the separation spacing of 0.05mm to 1mm in the winding direction (D3 )condition.

Preferably, a predetermined gap may be provided between the bottom of the cutting groove of the section 61 (the portion indicated by D4 in FIG. 5 ) and the active material layer 42 . Preferably, the gap is 0.2mm to 4mm.

Referring to Fig. 4, when the bent portions of the uncoated portions 43a, 43a' are divided into a plurality of sections 61, the plurality of sections 61 may form a plurality of section groups from the core to the outer periphery and belong to the same section group. The sections may be identical to each other in at least one of width in the winding direction, height in the winding axis direction, and separation pitch in the winding direction.

Preferably, at least a portion of the plurality of segment groups may be disposed at the same winding turn of the electrode assembly 80 . In one embodiment, the segments included in each group may constitute at least one winding turn in the winding structure of electrode assembly 80 . In another embodiment, the segments included in each group may constitute two or more winding turns in the winding structure of electrode assembly 80 .

9 a is a partial cross-sectional view showing an electrode assembly having a radius of 22 mm and included in a cylindrical battery with a form factor of 4680, in which the uncoated portion 43 a of the first electrode 40 divided into a plurality of sections 61 is directed from the outer circumference toward the core. Bending to form a bent surface area F, in a part of the bent surface area F, the uncoated portion 43a overlaps into more than 10 layers in the radial direction, and an increase in the number of stacks occurs in the radial direction of the electrode assembly 80 Zones and stacked number of zones uniformly.

Referring to Figure 9a, the number of stacked layers of the uncoated portion 43a in the bent surface area F increases sequentially from the outer circumference of the electrode assembly 80 toward the core and reaches a maximum value, and maintains a maximum value in a predetermined radius area, and then near the core Decrease by 1 or 2. The radius area near the core may be called a stacking number reduction area.

Hereinafter, a radius area in which the number of stacked layers of the uncoated portion 43 a sequentially increases from the outer circumference toward the core of the electrode assembly 80 to a maximum value is defined as a stacking number increasing area, and in which the number of stacked layers of the uncoated portion 43 a is maintained at The area of the maximum value together with the remaining area near the core is defined as the stacking number uniform area. Since the stacked number uniform region includes a region in which the number of stacked layers of the uncoated portion 43a is maintained at a maximum value, the bent surface region F, which corresponds to the optimal welding region, is flatter than other regions.

In FIG. 9 a , the uncoated portion 43 a is divided into trapezoidal-shaped sections as shown in FIG. 5 , and only the upper portion of the uncoated portion 43 a is depicted based on the bottom 63 a of the cutting groove 63 . The uncoated portion 43 a is not shown in the portion corresponding to the cross section of the cutting groove 63 .

The actual bending points of the sections 61 are not exactly the same and are spaced a predetermined distance from the lower end of the cutting groove 63 . As the number of stacked layers of the uncoated portion 43 a increases toward the core, overlapping resistance occurs, so it is preferable to perform bending at a point spaced a predetermined distance from the lower end of the cutting groove 63 . The separation distance is 2 mm or less, preferably 1 mm or less. If there is a separation distance, the sections 61 overlap better in the radial direction.

The bent surface region F is formed when sections located at different winding turns overlap in the radial direction of the electrode assembly 80 . In the embodiment shown in Figure 9a, the sections 61 do not overlap in the circumferential direction. That is, as shown in (a) of FIG. 6 , there is a gap between the sides of the sections 61 . The conditions for the gap can be met by adjusting the width, height, separation distance, lower inner corner, etc. of the section. The bending surface area F when the sections overlap in the circumferential direction will be described later with reference to Figure 9b.

In this embodiment, the radius ( _rc ) of the core of electrode assembly 80 is 4 mm. Furthermore, the height of the sections starts from 3mm. There is no section in the uncoated portion 43a based on the radius of the electrode assembly from 4 mm to 7 mm. That is, there is a section in an area with a radius of 7 mm to 22 mm in the total radius of 22 mm of the electrode assembly, and the width of the radius area where the section 61 is present is 15 mm. If, based on the radius of the core ( _rc ), at most 10% of the core is covered by the segments, the point at which the segments are started can be moved towards the core.

In the winding structure, sections with a height of 3 mm are provided starting from the winding turns with a radius of approximately 7 mm. Starting from a 7mm radius of the rolled structure, the height of the section increases by 1mm for every 1mm increase in radius from the core towards the periphery. The periodicity of the height increments of the segments may vary in the range of 0.2 mm to 1.2 mm per unit radius (1 mm).

(a) of FIG. 9a is a case where the maximum height of the segment is 8 mm. In this case, the sections are set starting from a point where the radius of the electrode assembly is 7 mm from the center of the core. Only then, when the section with a height of 3 mm is bent towards the core, does the section not cover the core with a radius of 4 mm. When the radius increases from 7mm to 12mm, the height of the segments increases in 5 steps from 3mm to 8mm. Furthermore, the height of the segments is maintained at 8mm in the radius from 12mm to 22mm. In this embodiment, the height variable area of the segment is in the radius range of 7 mm to 12 mm, and the height variable area ratio is 28% (5/18, rounded to zero decimal places, which will apply equally below) .

(b) of FIG. 9a is a case where the maximum height of the segment is 7 mm. Furthermore, in this case, the sections are provided starting from a point where the radius of the electrode assembly is 7 mm from the center of the core. Only then, when the section with a height of 3 mm is bent towards the core, does the section not cover the core with a radius of 4 mm. When the radius increases from 7mm to 11mm, the height of the segments increases in 4 steps from 3mm to 7mm. Furthermore, the height of the segments is maintained at 7mm in the radius from 12mm to 22mm. In this embodiment, the height variable area of the segment is in the radius range of 7 mm to 11 mm, and the height variable area ratio is 22% (4/18).

(c) of FIG. 9a is a case where the maximum height of the segment is 6 mm. Furthermore, in this case, the sections are provided starting from a point where the radius of the electrode assembly is 7 mm from the center of the core. Only then, when the section with a height of 3 mm is bent towards the core, does the section not cover the core with a radius of 4 mm. When the radius increases from 7mm to 10mm, the height of the segments increases in 3 steps from 3mm to 6mm. In addition, the height of the segments is maintained at 6mm in the radius from 10mm to 22mm. In this embodiment, the height variable area of the segment is in the radius range of 7 mm to 10 mm, and the height variable area ratio is 17% (3/18).

In the embodiment shown in (a), (b) and (c) of Figure 9a, the variable height areas of the segments start from a radius of 7 mm. In addition, the highly variable region ratio is 17% to 28%. This ratio range is included in the above-described preferred range of 1% to 56%.

Referring to Fig. 9a, the number of stacked layers of the uncoated portion 43a increases sequentially from the outer periphery toward the core. Furthermore, it can be found that even if the minimum length of the sections is the same as 3mm, the maximum number of stacked layers increases to 12, 15, and 18 as the maximum length of the sections increases to 6mm, 7mm, and 8mm. Furthermore, the thickness of the bent surface area F increases in proportion to the number of stacked layers.

For example, when the maximum height of the section is 8 mm, the number of stacked layers of the uncoated portion 43 a increases to 18 from the outer circumference to the core of the electrode assembly 80 in a 7 mm radius region, and at a diameter where the increase in the number of stacked layers stops. In the 8 mm radius area facing the core, the number of stacked layers of the uncoated portion 43a is uniformly maintained at the level of 18. In this embodiment, in the uniform stacking number area, the number of stacking layers is at least 16, and the radial width thereof is 8 mm. The width of the stacked number uniform zone is 53% compared to the radial length of the winding turns including the segment (15 mm) (8/15, rounded to zero decimal places, this will apply equally below).

As another example, when the maximum height of the section is 7 mm, the number of stacked layers of the uncoated portion 43 a increases to 15 from the outer circumference to the core of the electrode assembly 80 in a 6 mm radius area, and stops from the number of stacked layers In the 9 mm radius area of the increasing radial position toward the core, the number of stacked layers of the uncoated portion 43a is uniformly maintained at the level of 15. Therefore, the radial width of the area with a uniform number of stacks is 9 mm, and in the area with a uniform number of stacks, the number of stacked layers is at least 13. The width of the uniform zone of stack count is 60% (9/15) compared to the radial length of the winding turns including the segment (15 mm).

As another example, when the maximum height of the section is 6 mm, the number of stacked layers of the uncoated portion 43a increases to 12 from the outer circumference to the core of the electrode assembly 80 in a 5 mm radius area, and stops from the number of stacked layers In the 10 mm radius area of the increasing radial position toward the core, the number of stacked layers of the uncoated portion 43a is uniformly maintained at the level of 12. Therefore, the radial width of the area with a uniform number of stacks is 10 mm, and in the area with a uniform number of stacks, the number of stacked layers is at least 11. The width of the uniform zone of stack count is 67% (10/15) compared to the radial length of the winding turns including the segment (15 mm).

According to this embodiment, it can be understood that when the minimum length of the section is 3mm and the maximum length of the section is 6mm, 7mm and 8mm, the length of the stacking number increasing zone in which the number of stacked layers gradually increases increases to 5mm, 5mm and 8mm respectively. 6 mm and 7 mm, and the ratio of the stacked number uniform area in which the number of stacked layers of the uncoated portion 43a is 10 or more is 53% to 67%.

At the same time, the thickness of the bent surface area F increases in proportion to the number of stacked layers of the uncoated portion 43a. The number of stacked layers of the uncoated portion 43a may be reduced to 10, depending on the minimum height and the maximum height of the sections in the variable height region, so the number of stacked layers of the uncoated portion 43a may be 10 to 18. In one embodiment, when the uncoated portion 43a is aluminum and its thickness is 10 μm to 25 μm, the thickness of the bent surface region F may be 100 μm to 450 μm. In another embodiment, when the uncoated portion 43a is copper and its thickness is 5 μm to 20 μm, the thickness of the bent surface region F may be 50 μm to 360 μm. If the thickness of the bent surface area F satisfies the above numerical range conditions, then when the current collector is welded to the bent surface area F using a laser, the bent surface area F fully absorbs the laser energy. Therefore, a weld bead is formed in a sufficient volume on the bent surface area F to increase the welding strength. In addition, it is possible to prevent the diaphragm and the like located under the bent surface area F from being damaged due to the welding portion being perforated by the laser.

Preferably, the current collector can be welded to the bent surface area F. Based on the radial direction, the welding area of the current collector can overlap at least partially with the area of uniform stacking number.

Preferably, 50% to 100% of the welding area of the current collector may overlap with a uniform stacking number area in the radial direction of the electrode assembly. When the overlap ratio of the welding zone is increased, it is preferable in terms of improving the welding strength and increasing the weld bead volume. In the welding area of the current collector, the remaining area that does not overlap with the area of uniform stacking number may overlap with the area of increased stacking number.

Meanwhile, as described with reference to FIG. 6 , when the section 61 of the uncoated portion 43 a is bent to form the bent surface area F, if the lower inner angle of the sections included in each section group satisfies the condition of Formula 1 , then adjacent sections 61 located in the same winding turn can overlap each other in the circumferential direction, while the sides of adjacent sections 61 intersect. In this case, the number of stacked layers of the uncoated portion 43a can be further increased in the radial direction of the electrode assembly.

Figure 9b is a cross-sectional view of the bending surface area F, illustrating an increased stacking number area and a uniform stacking number area when the sections overlap in the circumferential direction.

Referring to Fig. 9b, the number of stacked layers of the uncoated portion 43a increases sequentially from the outer periphery toward the core. As in the embodiment of Figure 9a, the height-variable area of the segment starts from a radius of 7 mm. The height of the segments starts at 3mm and increases by 1mm for every 1mm increase in radius. As the maximum value of the section height increases to 6mm, 7mm, 8mm, 9mm and 10mm, the number of stacked layers at the radial position where the stacking number uniform zone starts increases to 18, 22, 26, 30 and 34. Under the same conditions where the maximum values of the section heights are 6 mm, 7 mm and 8 mm, the number of stacked layers is 6 to 8 greater than that of the embodiment of Figure 9a. This is because the segments overlap circumferentially.

Specifically, when the maximum value of the section height is 10 mm, the number of stacked layers of the uncoated portion 43a increases to 34 from the outer periphery to the core of the electrode assembly 80 in the 9 mm radius area (number of stacked layers increase area), and in In the 6 mm radius region toward the core from the radial position where the number of stacked layers stops increasing, the number of stacked layers of the uncoated portion 43a is maintained at 34, and the number of stacked layers further increases to 39 near the core. The number of stacked layers increases near the core because the segments overlap more circumferentially as they get closer to the core. A radius region near the core in which the number of stacks is further increased may be defined as a region of additional increase in the number of stacks. In this embodiment, in the uniform stacking number area, the number of stacking layers is 34 or more, and its radial width is 6 mm. The stack number uniform area starts from a radius of 7mm and the stack number uniform area ratio compared to the radial length of the winding turns including the segment (15 mm) is 40% (6/15, rounded to zero decimal places, this will be the same applies below).

As another example, when the maximum value of the section height is 9 mm, the number of stacked layers of the uncoated portion 43a increases to 30 from the outer periphery to the core of the electrode assembly 80 in the 8 mm radius area, and in the 8 mm radius area from the number of stacked layers In the 7 mm radius region toward the core where the radial position stops increasing, the number of stacked layers of the uncoated portion 43a is maintained at 30, and then further increases to 36 near the core. Therefore, the radial width of the uniform stacking number area is 7 mm, and the number of stacking layers in the uniform stacking number area is 30 or more. The stack number uniform zone starts from a radius of 7 mm and the ratio of the stack number uniform zone compared to the radial length of the winding turns including the segment (15 mm) is 47% (7/15).

As yet another example, when the maximum value of the section height is 8 mm, the number of stacked layers of the uncoated portion 43a increases to 26 from the outer periphery to the core of the electrode assembly 80 in a 7 mm radius area, and in the 7 mm radius region from the number of stacked layers In the 8 mm region toward the core where the radial position stops increasing, the number of stacked layers of the uncoated portion 43a is maintained at 26, and then further increases to 28 near the core. Therefore, the radial width of the uniform stacking number area is 8 mm, and the number of stacking layers in the uniform stacking number area is 26 or more. The stack number uniformity zone starts from a radius of 7 mm and the ratio of the stack number uniformity zone compared to the radial length of the winding turns including the segment (15 mm) is 53% (8/15).

As yet another example, when the maximum value of the section height is 7 mm, the number of stacked layers of the uncoated portion 43a increases to 22 from the outer periphery to the core of the electrode assembly 80 in a 6 mm radius area, and in the 6 mm radius region from the number of stacked layers In the 9 mm radius region toward the core where the radial position stops increasing, the number of stacked layers of the uncoated portion 43a is maintained at 22, and then further increases to 23 near the core. Therefore, the radial width of the uniform stacking number area is 9 mm, and the number of stacking layers in the uniform stacking number area is 22 or more. The stack number uniform zone starts from a radius of 7 mm and the ratio of the stack number uniform zone compared to the radial length of the winding turns (15 mm) including the segment is 60% (9/15).

As yet another example, when the maximum value of the section height is 6 mm, the number of stacked layers of the uncoated portion 43a increases to 18 from the outer periphery to the core of the electrode assembly 80 in a 5 mm radius area, and the number of stacked layers is increased from In the 10 mm radius region toward the core where the radial position stops increasing, the number of stacked layers of the uncoated portion 43a is maintained at 18, and then further increases to 20 near the core. Therefore, the radial width of the uniform stacking number area is 10 mm, and the number of stacking layers in the uniform stacking number area is 18 or more. The stack number uniformity zone starts from a radius of 7 mm and the ratio of the stack number uniform zone compared to the radial length of the winding turns including the segment (15 mm) is 67% (10/15).

According to the embodiment shown in Figure 9b, when the minimum value of the section height is 3mm and the maximum value of the section height is 6mm, 7mm, 8mm, 9mm and 10mm, the number of stacks in which the number of stacked layers gradually increases increases. Lengths increased to 5mm, 6mm, 7mm, 8mm and 9mm. Furthermore, it can be found that the ratio of the uniform stacking number area in which the number of stacking layers is 10 or more is 40% to 67%.

Meanwhile, in the embodiment of Fig. 9b, the thickness of the bent surface area F increases in proportion to the number of stacked layers of the uncoated portion 43a. The number of stacked layers of the uncoated portion 43a is 18 to 39. In one embodiment, when the uncoated portion 43a is aluminum and its thickness is 10 μm to 25 μm, the thickness of the bent surface area F may be 180 μm to 975 μm. In another embodiment, when the uncoated portion 43a is copper and its thickness is 5 μm to 20 μm, the thickness of the bent surface region F may be 90 μm to 780 μm. If the thickness of the bent surface area F satisfies the above numerical range conditions, then when the current collector is welded to the bent surface area F using a laser, the bent surface area F fully absorbs the laser energy. Therefore, a weld bead is formed in a sufficient volume on the bent surface area F to increase the welding strength. In addition, it is possible to prevent the diaphragm and the like located under the bent surface area F from being damaged due to the welding portion being perforated by the laser.

Preferably, the welding area of the current collector may at least partially overlap with the area of uniform stacking number based on the radial direction. Preferably, 50% to 100% of the welding area of the current collector may overlap with a uniform stacking number area in the radial direction of the electrode assembly 80 . When the overlap ratio of the welding zone is increased, it is preferable in terms of welding strength. An area of the welding area of the current collector that does not overlap with the area of uniform stacking number may overlap with the area of increased stacking number.

In the embodiment shown in FIGS. 9a and 9b , it is obvious to those skilled in the art that the stacked number of uniform areas of the uncoated portion 43a can be determined according to the radius (R) of the electrode assembly, the radius ( _rc ) of the core, The minimum and maximum values of the segment height in the segment height variable region increase or decrease according to the increase in height of the segment in the radial direction of the electrode assembly.

The ratio of stacked number uniform areas is inversely proportional to the radius of the core ( _rc ). Furthermore, when the minimum heights of the segments are the same, the ratio of stacked regions with a uniform number increases as the radial width of the height-variable regions decreases. Furthermore, when the maximum heights of the segments are the same, the ratio of stacked regions with a uniform number increases as the radial width of the height-variable regions decreases.

In one embodiment, when the radius (R) of the electrode assembly is 22 mm, the radius ( _rc ) of the core is 2 mm and the height of the segment is in a radius of 9 mm to 12 mm (which is the height variable region of the segment) from When 7mm is changed to 10mm, the ratio of the stacking number uniform area can be reduced to the level of 30%.

In another embodiment, when the radius (R) of the electrode assembly is 22 mm, the radius ( _rc ) of the core is 2 mm and the height of the segment is in a radius of 5 mm to 6 mm (which is the height variable region of the segment) When changing from 3mm to 4mm, the ratio of the stacking number uniform area can be increased to the level of 85%.

Therefore, the radial length of the uniform stack number zone may be 30% or more, preferably 30% to 85%, compared to the radial length of the winding turns including the segments.

Meanwhile, as described with reference to FIGS. 9a and 9b , when the maximum height of the segments in the height-uniform region of the segments is 6 mm to 10 mm, it is possible to adjust the height of the segments in the radial direction by changing the minimum height of the segments and the height of the segments in the radial direction. The height increment adjusts the number of stacked layers of the uncoated portion 43a in the uniform stacking number area in the range of 10 to 39. The stacked number uniform area of the bending surface area F includes an area formed by the sections included in the bending height uniform area. The thickness of the bent surface area F changes according to the thickness of the material constituting the uncoated portion 43a. When the uncoated part 43a is made of aluminum and has a thickness of 10 μm to 25 μm, the stack thickness of the uncoated part in the bent surface area F is 100 μm (0.1 mm) to 975 μm (0.975 mm). In this case, the stacking thickness of the uncoated portion in the bent surface area F is the same as that in the bent surface area F formed by bending the sections with a height of 6 mm to 10 mm included in the highly uniform area. The ratio of the height is 1.0% (0.1mm/10mm) to 16.3% (0.975mm/6mm). In another embodiment, when the uncoated part 43a is made of copper and has a thickness of 5 μm to 20 μm, the stack thickness of the uncoated parts in the bent surface area F is 50 μm (0.05 mm) to 780 μm (0.780 μm). mm). In this case, the stacking thickness of the uncoated portion in the bent surface area F is the same as that in the bent surface area F formed by bending the sections with a height of 6 mm to 10 mm included in the highly uniform area. The ratio of the height is 0.5% (0.05mm/10mm) to 13.0% (0.780mm/6mm). If the ratio of the thickness of the bent surface region (F) to the height of the section included in the highly uniform region satisfies the above numerical range, desired welding strength can be achieved when the current collector is welded to the bent surface region F.

Various electrode assembly structures according to embodiments (variations) of the present disclosure may be applied to cylindrical batteries or any other batteries known in the art.

Preferably, the cylindrical battery may be, for example, a cylindrical battery having a form factor ratio (defined as the diameter of the cylindrical battery divided by the height, ie, the ratio of diameter (Φ) to height (H)) of approximately greater than 0.4.

Here, the form factor refers to a value indicating the diameter and height of a cylindrical battery. The form factor of the cylindrical battery according to one embodiment of the present disclosure may be, for example, 46110, 4875, 48110, 4880, 4680, etc. In the numerical representation of the form factor, the first two digits indicate the diameter of the cell, and the remaining digits indicate the height of the cell.

When an electrode assembly with a jointless structure is applied to a cylindrical battery with a shape factor ratio greater than 0.4, a large stress is applied in the radial direction when the uncoated portion is bent, so that the uncoated portion may be easily torn crack. In addition, when welding the current collector to the bent surface area of the uncoated part, it is necessary to sufficiently increase the number of stacked layers of the uncoated part in order to fully ensure the welding strength and reduce the resistance. This requirement can be achieved with electrodes and electrode assemblies according to embodiments (modifications) of the present disclosure.

The battery according to one embodiment of the present disclosure may be a cylindrical battery having an approximately cylindrical shape with a diameter of approximately 46 mm, a height of approximately 110 mm, and a shape factor ratio of 0.418.

The battery according to another embodiment may be a cylindrical battery having a generally cylindrical shape with a diameter of approximately 48 mm, a height of approximately 75 mm, and a form factor ratio of 0.640.

The battery according to yet another embodiment may be a cylindrical battery having an approximately cylindrical shape with a diameter of approximately 48 mm, a height of approximately 110 mm, and a form factor ratio of 0.436.

The battery according to yet another embodiment may be a cylindrical battery having an approximately cylindrical shape with a diameter of approximately 48 mm, a height of approximately 80 mm, and a form factor ratio of 0.600.

The battery according to yet another embodiment may be a cylindrical battery having an approximately cylindrical shape with a diameter of approximately 46 mm, a height of approximately 80 mm, and a form factor ratio of 0.575.

Batteries with a form factor ratio below about 0.4 have traditionally been used. That is, conventionally, for example, 1865 batteries, 2170 batteries, etc. are used. The 1865 cell has a diameter of approximately 18mm, a height of approximately 65mm, and a form factor ratio of 0.277. The 2170 cell has a diameter of approximately 21mm, a height of approximately 70mm, and a form factor ratio of 0.300.

Hereinafter, a cylindrical battery according to one embodiment of the present disclosure will be described in detail.

FIG. 10 shows a cross-sectional view of the cylindrical battery 190 taken along the Y-axis direction according to one embodiment of the present disclosure.

Referring to FIG. 10 , a cylindrical battery 190 according to one embodiment of the present disclosure includes an electrode assembly 110 having a first electrode, a separator, and a second electrode, a battery case 142 for accommodating the electrode assembly 110 , and a sealing battery case. 142 and a sealing body 143 at the open end.

The battery case 142 is a cylindrical container with an opening at the top. Battery housing 142 is made of a conductive metal material such as aluminum or steel. The battery case 142 houses the electrode assembly 110 in an interior space with a top opening and also houses the electrolyte.

The electrolyte may be a salt having a structure such as A ^{+ B-} . Here, A ⁺ includes alkali metal cations such as Li ⁺ , Na ⁺ or K ⁺ or combinations thereof. And B ^- includes at least one anion selected from the group consisting of: F ^- ; Cl ^- ; Br ^- ; I ^- ; NO ₃ ^- ; N(CN) ₂ ^- ; BF ₄ ^- ; ClO ₄ ^- ; AlO ₄ ^- ; AlCl ₄ ^- ; PF ₆ ^- ; SbF ₆ ^- ; AsF ₆ ^- ; BF ₂ C ₂ O ₄ ^- ; BC ₄ O ₈ ^- ; (CF ₃ ) ₂ PF ₄ ^- ; (CF ₃ ) ₃ PF ₃ ^- ; ( CF ₃ ) ₄ PF ₂ ^- ; (CF ₃ ) ₅ PF ^- ; (CF ₃ ) ₆ P ^- ; CF ₃ SO ₃ ^- ; C ₄ F ₉ SO ₃ ^- ; CF ₃ CF ₂ SO ₃ ^- ; (CF ₃ SO ₂ ) ₂ N ^- ; (FSO ₂ ) ₂ N ^- ; CF ₃ CF ₂ (CF ₃ ) ₂ CO ^- ; (CF ₃ SO ₂ ) ₂ CH ^- ; (SF ₅ ) ₃ C ^- ; (CF ₃ SO ₂ ) ₃ C ^- ; CF ₃ (CF ₂ ) ₇ SO ₃ ^- ; CF ₃ CO ₂ ^- ; CH ₃ CO ₂ ^- ; SCN ^- and (CF ₃ CF ₂ SO ₂ ) ₂ N ^- .

Electrolytes can also be dissolved in organic solvents. The organic solvent can be propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, Acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), γ-butyrolactone or mixtures thereof.

The electrode assembly 110 may have a core shape or any other pressed shape known in the art. As shown in FIG. 2 , the electrode assembly 110 may be manufactured by winding a laminate formed by sequentially laminating a lower separator, a first electrode, an upper separator, and a second electrode at least once based on the winding center C.

The first electrode and the second electrode have different polarities. That is, if one electrode has positive polarity, the other electrode has negative polarity. At least one of the first electrode and the second electrode may have the electrode structure according to the above embodiment (modification). Furthermore, the other one of the first electrode and the second electrode may have a conventional electrode structure or an electrode structure according to the embodiment (modification).

The uncoated portion 146a of the first electrode and the uncoated portion 146b of the second electrode protrude from the upper and lower portions of the electrode assembly 110, respectively.

The sealing body 143 may include: a cap 143a; a first gasket 143b for providing airtightness and insulation between the cap 143a and the battery case 142; and a connecting plate 143c electrically and mechanically coupled to the cap 143a.

The cap 143a is a component made of conductive metal material, and covers the top opening of the battery case 142. The cap 143a is electrically connected to the uncoated portion 146a of the first electrode and is electrically insulated from the battery case 142 by the first gasket 143b. Therefore, the cap 143a can serve as the first electrode terminal of the cylindrical battery 140.

The cap 143 a is placed on the crimp portion 147 formed on the battery case 142 and fixed by the crimp portion 148 . Between the cap 143a and the crimping part 148, a first gasket 143b may be interposed to ensure the airtightness of the battery case 142 and the electrical insulation between the battery case 142 and the cap 143a. The cap 143a may have a protrusion 143d protruding upward from the center thereof.

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

The battery case 142 includes a crimp portion 147 and a crimp portion 148 on the top thereof. The curled portion 147 is formed by press-fitting the periphery of the outer peripheral surface of the battery case 142 . The crimp portion 147 prevents the electrode assembly 110 housed inside the battery case 142 from escaping through the top opening of the battery case 142, and can serve as a support portion on which the sealing body 143 is placed.

The crimping portion 148 is formed on the curling portion 147 . The crimping portion 148 has an extended and bent shape to cover the outer periphery of the cap 143a provided on the crimp portion 147 and a part of the upper surface of the cap 143a.

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

The first current collector 144 is coupled to the upper portion of the electrode assembly 110 . The first current collector 144 is made of a conductive metal material such as aluminum, copper, nickel, etc., and is electrically connected to the bent surface region F ₁ formed when the uncoated portion 146 a of the first electrode is bent.

Lead 149 may be connected to first current collector 144 . The lead 149 may extend upward above the electrode assembly 110 and be coupled to the connecting plate 143c or directly coupled to the lower surface of the cap 143a. Leads 149 may be connected to other components by soldering.

Preferably, the first current collector 144 may be integrally formed with the lead 149 . In this case, the lead 149 may have an elongated plate shape extending outward from near the center of the first current collector 144 .

The bent surface area (F ₁ ) of the first uncoated portion 146a and the first current collector 144 may be coupled, for example, by laser welding. Laser welding may be performed in a manner that locally melts the base material of current collector 144 . Laser welding can be replaced by resistance welding, ultrasonic welding, etc.

Preferably, the uncoated portion 146a is divided into a plurality of sections, and the bent surface area (F ₁ ) is formed by bending the plurality of sections toward the core C. In the bent surface region (F ₁ ), the radial length of the region where the number of stacked layers of the uncoated portion 146a is 10 or more may be 30% or more compared to the radial length of the winding turns including the segment , more preferably 30% to 85%.

The welding area between the bent surface area (F ₁ ) of the uncoated portion 146a and the first current collector 144 may overlap by more than 50% with the stacked number uniform area (W ₁ ) of the bent surface area (F ₁ ), And more preferably, the overlap ratio is higher.

When laser welding is used to weld the bent surface area (F ₁ ) of the uncoated portion 146 a and the first current collector 144 , the welding strength may be preferably 2 kgf/cm ² or more, and more preferably 4 kgf/cm ² or more. The upper limit of welding strength may depend on the specifications of the laser welding equipment. As an example, the welding strength can be set to 8 kgf/cm ² or less, or 6 kgf/cm ² or less. The laser power used to achieve welding strength changes depending on the laser welding equipment. In one embodiment, the laser power may be in the range of 250W to 320W. In another embodiment, the laser power may be adjusted within a range of 40% to 100% of the maximum power specification of the laser welding equipment.

When the welding strength satisfies the above numerical range, even if strong vibration is applied to the electrode assembly 110 along the winding axis direction and/or the radial direction, the characteristics of the welding interface will not deteriorate, and since the volume of the weld bead is sufficient, Can reduce the resistance of the welding interface.

The second current collector 145 may be coupled to the lower surface of the electrode assembly 110 . One side of the second current collector 145 may be coupled to the bent surface area (F ₂ ) formed when the uncoated portion 146 b of the second electrode is bent by welding, and the other side may be coupled to the battery case 142 by welding. Insole surface.

Preferably, the uncoated portion 146b is divided into a plurality of sections, and the bent surface area (F ₂ ) is formed by bending the plurality of sections toward the core C. In the bent surface area (F ₂ ), the radial length of the area in which the number of stacked layers of the uncoated portion 146 b is 10 or more may be 30% or more compared to the radial length of the winding turns including the section. , more preferably 30% to 85%.

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

The welding area between the bent surface area (F ₂ ) of the uncoated portion 146 b and the second current collector 145 may overlap the stacking number uniform area (W ₂ ) by more than 50%, and more preferably, the overlap ratio is more high.

When laser welding is used to weld the bent surface area (F ₂ ) of the uncoated portion 146 b and the second current collector 145 , the welding strength may be preferably 2 kgf/cm ² or more, and more preferably 4 kgf/cm ² or more. The upper limit of welding strength may depend on the specifications of the laser welding equipment. As an example, the welding strength can be set to 8 kgf/cm ² or less, or 6 kgf/cm ² or less. The laser power used to achieve welding strength changes depending on the laser welding equipment. In one embodiment, the laser power may be in the range of 250W to 320W. In another embodiment, the laser power may be adjusted within a range of 40% to 100% of the maximum power specification of the laser welding equipment.

When the welding strength satisfies the above numerical range, even if strong vibration is applied to the electrode assembly 110 along the winding axis direction and/or the radial direction, the characteristics of the welding interface will not deteriorate, and since the volume of the weld bead is sufficient, Can reduce the resistance of the welding interface.

Insulator 146 may cover first current collector 144 . The insulator 146 may cover the first current collector 144 at an upper surface thereof, thereby preventing the first current collector 144 from directly contacting the inner periphery of the battery case 142 .

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

The peripheral area of the edge of the insulator 146 may be interposed between the first current collector 144 and the crimp portion 147 to fix the coupling of the electrode assembly 110 and the first current collector 144 . Therefore, the movement of the connection body between the electrode assembly 110 and the first current collector 144 in the height direction of the battery 140 can be restricted, thereby improving the assembly stability of the battery 140 .

The insulator 146 may be made of insulating polymer resin. In one embodiment, insulator 146 may be made of polyethylene, polypropylene, polyimide, or polybutylene terephthalate.

The battery case 142 may further include an exhaust portion 152 formed at a lower surface thereof. The exhaust portion 152 corresponds to a region having a smaller thickness than the peripheral region of the lower surface of the battery case 142 . The exhaust portion 152 is structurally weaker than the peripheral area. Therefore, when an abnormality occurs in the cylindrical battery 190 and the internal pressure increases above a predetermined level, the exhaust part 152 may rupture so that the gas generated inside the battery case 142 is discharged to the outside.

The exhaust portion 152 may be formed continuously or discontinuously while drawing a circular shape at the lower surface of the battery case 142 . In one variation, the exhaust portion 152 may be formed in a linear pattern or other pattern.

FIG. 11 shows a cross-sectional view of a cylindrical battery 200 according to another embodiment of the present disclosure taken along the Y-axis direction.

Referring to FIG. 11 , the structure of the electrode assembly of the cylindrical battery 200 is substantially the same as the structure of the electrode assembly of the cylindrical battery 190 in FIG. 10 , except that other structures except the electrode assembly have been changed.

Specifically, the cylindrical battery 200 includes a battery case 171 through which a terminal 172 is mounted. The terminal 172 is mounted on the closed surface (upper surface in the figure) of the battery case 171 . The terminal 172 is riveted to the through hole of the battery case 171 with a second gasket 173 made of an insulating material interposed therebetween. The terminal 172 is exposed to the outside in a direction opposite to the direction of gravity.

The terminal 172 includes a terminal exposed portion 172a and a terminal insertion portion 172b. The terminal exposure portion 172a is exposed to the outside of the closed surface of the battery case 171. The terminal exposure portion 172a may be located approximately at a center portion of the closed surface of the battery case 171. The maximum diameter of the terminal exposure portion 172a may be larger than the maximum diameter of the through hole formed in the battery case 171. The terminal insertion portion 172b may be electrically connected to the uncoated portion 146a of the first electrode through an approximately central portion of the closed surface of the battery case 171. The terminal insertion part 172b may be riveted to the inner surface of the battery case 171. That is, the lower edge of the terminal insertion portion 172b may have a shape curved toward the inner surface of the battery case 171. The maximum diameter of the end portion of the terminal insertion portion 172b may be larger than the maximum diameter of the through hole of the battery case 171.

The lower surface of the terminal insertion portion 172b is substantially flat, and may be welded to the center portion of the first current collector 144 connected to the 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 case 171 . Insulator 174 covers the upper portion of first current collector 144 and the top edge of electrode assembly 110 . Therefore, it is possible to prevent the uncoated portion 146a exposed at the periphery of the electrode assembly 110 from contacting the inner surface of the battery case 171 having a different polarity to cause a short circuit.

The insulator 174 is in contact with the inner surface of the closed portion of the battery case 171 and with the upper surface of the first current collector 144 . For this purpose, the insulator 174 has a thickness corresponding to the separation distance between the inner surface of the closed portion of the battery case 171 and the upper surface of the first current collector 144, or has a thickness slightly larger than the separation distance.

Preferably, the first current collector 144 may be laser welded to the bent surface region F ₁ of the uncoated portion 146 a. At this time, welding is performed in a region including a stacked number uniform region in which the number of stacked layers of the uncoated portion 146a is 10 or more in the bent surface region F ₁ of the uncoated portion 146 a.

Compared with the radial length of the winding turns including the sections, the radial length of the region where the number of stacked layers of the uncoated portion 146a is 10 or more may be 30% or more, and more preferably 30% to 85%.

The welding area between the bent surface area (F ₁ ) of the uncoated portion 146a and the first current collector 144 may overlap with the stacking number uniform area (W ₁ ) by more than 50%, and more preferably, the overlap ratio is more high.

When laser welding is used to weld the bent surface area (F ₁ ) of the uncoated portion 146 a and the first current collector 144 , the welding strength may be preferably 2 kgf/cm ² or more, and more preferably 4 kgf/cm ² or more. The upper limit of welding strength may depend on the specifications of the laser welding equipment. As an example, the welding strength can be set to 8 kgf/cm ² or less, or 6 kgf/cm ² or less. The laser power used to achieve welding strength changes depending on the laser welding equipment. In one embodiment, the laser power may be in the range of 250W to 320W. In another embodiment, the laser power may be adjusted within a range of 40% to 100% of the maximum power specification of the laser welding equipment.

When the welding strength satisfies the above numerical range, even if strong vibration is applied to the electrode assembly 110 along the winding axis direction and/or the radial direction, the characteristics of the welding interface will not deteriorate, and since the volume of the weld bead is sufficient, Can reduce the resistance of the welding interface.

The second gasket 173 is interposed between the battery case 171 and the terminal 172 to prevent the battery case 171 and the terminal 172 having opposite polarities from electrically contacting each other. Therefore, the upper surface of the battery case 171 having an approximately flat shape can be used as the second electrode terminal of the cylindrical battery 100 .

The second gasket 173 includes a gasket exposure part 173a and a gasket insertion part 173b. The gasket exposed portion 173a is interposed between the terminal exposed portion 172a of the terminal 172 and the battery case 171. The gasket insertion portion 173b is interposed between the terminal insertion portion 172b of the terminal 172 and the battery case 171. When the terminal insertion part 172b is riveted, the gasket insertion part 173b may be deformed together so as to be in close contact with the inner surface of the battery case 171. The second gasket 173 may be made of, for example, a polymer resin having insulating properties.

The gasket exposed portion 173a of the second gasket 173 may have an extended shape to cover the outer periphery of the terminal exposed portion 172a of the terminal 172. When the second gasket 173 covers the outer periphery of the terminal 172, it is possible to prevent a short circuit from occurring when an electrical connection such as a bus bar is coupled to the battery case 171 and/or the upper surface of the terminal 172. Although not shown in the figure, the gasket exposed part 173a may have an extended shape so as to cover not only the outer peripheral surface of the terminal exposed part 172a but also a part of the upper surface thereof.

When the second gasket 173 is made of polymer resin, the second gasket 173 may be coupled to the battery case 171 and the terminal 172 by thermal melting. In this case, the airtightness at the coupling interface between the second gasket 173 and the terminal 172 and the coupling interface between the second gasket 173 and the battery case 171 can be enhanced. Meanwhile, when the gasket exposed portion 173a of the second gasket 173 has a shape extending to the upper surface of the terminal exposed portion 172a, the terminal 172 may be integrally coupled with the second gasket 173 through insert injection molding.

In the upper surface of the battery case 171 , the remaining area 175 other than 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 .

The second current collector 176 is coupled to the lower portion 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 second uncoated portion 146b of the second electrode.

Preferably, the second current collector 176 is electrically connected to the battery case 171 . To this end, at least a portion of the edge of the second current collector 176 may be interposed and fixed between the inner surface of the battery case 171 and the first gasket 178b.

In one embodiment, at least a portion of the edge of the second current collector 176 may be fixed to the crimp portion 180 by welding in a state of being supported on a lower surface of the crimp portion 180 formed at the bottom of the battery case 171 . In one variation, at least a portion of the edge of the second current collector 176 may be directly welded to the inner wall surface of the battery case 171 .

Preferably, the second current collector 176 and the bent surface area (F ₂ ) of the uncoated portion 146 b may be coupled by welding (eg, laser welding). At this time, welding is performed in a region including a uniform stacking number region in which the number of stacked layers of the uncoated portion 146b is 10 or more in the bent surface region (F ₂ ) of the uncoated portion 146 b.

Compared with the radial length of the winding turns including the section, the radial length of the region where the number of stacked layers of the uncoated portion 146b is 10 or more may be 30% or more, and more preferably 30% to 85%.

The welding area between the bent surface area (F ₂ ) of the uncoated portion 146 b and the second current collector 176 may overlap with the stacking number uniform area (W ₂ ) by more than 50%, and more preferably, the overlap ratio is more high.

When laser welding is used to weld the bent surface area (F ₂ ) of the uncoated portion 146 b and the second current collector 176 , the welding strength may be preferably 2 kgf/cm ² or more, and more preferably 4 kgf/cm ² or more.

When the welding strength satisfies the above numerical range, even if strong vibration is applied to the electrode assembly 110 along the winding axis direction and/or the radial direction, the characteristics of the welding interface will not deteriorate, and since the volume of the weld bead is sufficient, Can reduce the resistance of the welding interface.

The sealing body 178 for sealing the lower open end of the battery case 171 includes a cap 178a and a first gasket 178b. The first gasket 178b electrically separates the cap 178a and the battery case 171. Crimp 181 secures the edge of cap 178a and first gasket 178b together. The cap 178a has an exhaust portion 179. The arrangement of the exhaust portion 179 is substantially the same as the above-mentioned embodiment (modification).

Preferably, cap 178a is made of conductive metallic material. However, since the first gasket 178b is interposed between the cap 178a and the battery case 171, the cap 178a does not have polarity. The sealing body 178 seals the open end of the lower portion of the battery case 171 and serves to vent gas when the internal pressure of the battery 200 increases beyond a critical value.

Preferably, the terminal 172 electrically connected to the uncoated portion 146a of the first electrode serves as the first electrode terminal. Furthermore, in the upper surface of the battery case 171 electrically connected to the uncoated portion 146b of the second electrode via the second current collector 176, the portion 175 other than the terminal 172 serves as having a different polarity from the first electrode terminal. of the second electrode terminal. If the two electrode terminals are located at the upper portion of the cylindrical battery 200 as described above, electrical connection members such as bus bars may be arranged only on one side of the cylindrical battery 200 . This simplifies the battery pack structure and improves energy density. In addition, since the portion 175 serving as the second electrode terminal has an approximately flat shape, a sufficient bonding area for bonding electrical connection components such as bus bars can be ensured. Therefore, the cylindrical battery 200 can reduce the resistance at the coupling portion of the electrical connection parts to a desired level.

In the present disclosure, even if the uncoated portions 146a, 146b are bent toward the core, the core C of the electrode assembly 110 can be opened upward without being blocked.

That is, as shown in FIG. 4 , the height of the uncoated portions of the first electrode and the second electrode (especially the height of the core-side uncoated portion A) is designed to be low and adjacent to the core-side uncoated portion A The height variable area of the section 61 is set so that by adjusting the height of the section 61 closest to the core-side uncoated portion A, even if the uncoated portion near the core of the electrode assembly 110 is bent, the core C of the electrode assembly 110 Nor will it be blocked.

When the core C is not blocked, there is no difficulty in the electrolyte injection process, and the electrolyte injection efficiency is improved. Furthermore, by inserting a welding jig through the core C, the welding process between the current collector 145 and the bottom of the battery case 142 or the welding process between the current collector 144 and the terminal 172 can be easily performed.

When the uncoated parts 146a, 146b have a segment structure, if the width and/or height of the segments and/or the separation pitch are adjusted to meet the numerical range of the above embodiment, the segments overlap in multiple layers to fully ensure The welding strength when the section is bent, and no empty space (gap) is formed on the bending surface area (F ₁ , F ₂ ).

In the present disclosure, the welding areas of the first current collector 144 and the second current collector 176 may be spaced apart by more than 4 mm in the radial direction based on the center of the core C of the electrode assembly 110 and may be spaced apart by 50% of the radius of the electrode assembly 110 % distance. The separation distance of 4 mm is determined taking into account the minimum radius of core C (2 mm) and the minimum height of section 61 (2 mm). The distance is set to be less than 50% of the radius of the electrode assembly 110 to ensure a sufficient welding area.

Furthermore, the welding area of the first current collector 144 and the welding area of the second current collector 176 may extend from positions spaced substantially the same distance from the center of the core C of the electrode assembly 110 in the radial direction of the electrode assembly. At this time, the extension length of the welding area of the first current collector 144 is preferably greater than the extension length of the welding area of the second current collector 176 .

Meanwhile, the first current collector 144 and the second current collector 176 may have new structures as shown in FIGS. 12 and 13 .

FIG. 12 is a top plan view illustrating first current collector 144 according to one embodiment of the present disclosure.

Referring to FIG. 12 , the first current collector 144 may include an edge portion 144a, a first uncoated portion coupling portion 144b, and a terminal coupling portion 144c. The edge portion 144a is provided on the electrode assembly 110. The edge portion 144a may have a substantially frame shape having an empty space S formed therein. In the drawings of the present disclosure, only the case where the edge portion 144a has a substantially circular frame shape is shown, but the present disclosure is not limited thereto. The edge portion 144a may have a generally rectangular frame shape, a hexagonal frame shape, an octagonal frame shape, or other frame shapes other than the frame shapes shown.

The diameter of the terminal coupling portion 144c may be equal to or larger than the diameter of the flat portion formed on the bottom surface of the terminal 172 in order to ensure a soldering area for coupling with the flat portion formed on the bottom surface of the terminal 172.

The first uncoated portion coupling portion 144b extends inwardly from the edge portion 144a and is coupled to the uncoated portion 146a. The terminal coupling portion 144c is spaced apart from the first uncoated portion coupling portion 144b and is positioned inside the edge portion 144a. The terminal coupling portion 144c may be coupled to the terminal 172 by welding. The terminal coupling portion 144c may, for example, be located approximately in the center of the interior space surrounded by the edge portion 144a. The terminal coupling part 144c may be provided at a position corresponding to a hole formed in the core C of the electrode assembly 110. The terminal coupling part 144c may be configured to cover the hole formed in the core C of the electrode assembly 110 so that the hole formed in the core C of the electrode assembly 110 is not exposed outside the terminal coupling part 144c. For this reason, 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.

The first uncoated portion coupling portion 144b and the terminal coupling portion 144c may not be directly connected, but may be provided spaced apart from each other and indirectly connected via the edge portion 144a. Since 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 connected to each other but are connected via the edge portion 144a as described above, when an impact and When/or vibrating, the impact 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 can be dispersed. In the drawings of the present disclosure, only the case where four first uncoated portion coupling portions 144b are provided is shown, but the present disclosure is not limited thereto. The number of the first uncoated portion coupling portions 144b may be determined differently taking into account manufacturing difficulty according to the complexity of the shape, electrical resistance, space inside the edge portion 144a considering electrolyte impregnation, and the like.

The first current collector 144 may further include a bridge portion 144d extending inwardly from the edge portion 144a and connected to the terminal coupling portion 144c. At least a portion of the bridge portion 144d may have a smaller cross-sectional area than the first uncoated portion coupling portion 144b and the edge portion 144a. For example, at least a portion of the bridge portion 144d may be formed to have a smaller width and/or thickness than the first uncoated portion coupling portion 144b. In this case, the resistance in the bridge portion 144d increases, so when the current flows through the bridge portion 144d, the relatively large resistance causes a part of the bridge portion 144d to melt due to overcurrent heating, and therefore, the overcurrent is irreversibly blocked. . Considering the overcurrent blocking function, the cross-sectional area of the bridge portion 144d can be adjusted to an appropriate level.

The bridge portion 144d may include a tapered portion 144e whose width gradually decreases from the inner surface of the edge portion 144a toward the terminal coupling portion 144c. When the tapered portion 144e is provided, the rigidity of the component can be increased at the connection between the bridge portion 144d and the edge portion 144a. When the tapered portion 144e is provided, during the manufacturing process of the cylindrical battery 200, for example, a transfer device and/or a worker can easily and safely transport the first current collector 144 and/or the first current collector 144 by clamping the tapered portion 144e. A connection body between the current collector 144 and the electrode assembly 110 . That is, when the tapered portion 144e is provided, product defects that may occur by clamping portions welded to other components such as the first uncoated portion coupling portion 144b and the terminal coupling portion 144c can be prevented.

A plurality of first uncoated portion coupling portions 144b may be provided. The plurality of first uncoated portion coupling portions 144b may be disposed at substantially regular intervals from each other in the extending direction of the edge portion 144a. The extension length of each of the plurality of first uncoated portion coupling portions 144b may be substantially equal to each other. The first uncoated portion coupling portion 144b may be coupled to the bent surface area (F ₁ ) of the uncoated portion 146a by laser welding. The welding pattern 144f formed by welding between the first uncoated portion coupling portion 144b and the bent surface area (F ₁ ) may have a structure extending in the radial direction of the electrode assembly 110. The welding pattern 144f may be a line pattern or a dot array pattern.

The terminal coupling part 144c may be provided to be surrounded by a plurality of first uncoated part coupling parts 144b. The terminal coupling portion 144c may be coupled to the terminal 172 by welding. The bridge portion 144d may be positioned between a pair of first uncoated portion coupling portions 144b adjacent to each other. In this case, the distance from the bridge portion 144d to either one of the pair of first uncoated portion coupling portions 144b along the extending direction of the edge portion 144a may be substantially equal to the distance from the bridge portion 144d along the extending direction of the edge portion 144a. The distance to the other of the pair of first uncoated portion coupling portions 144b. The plurality of first uncoated portion coupling portions 144b may be formed to have substantially the same cross-sectional area. The plurality of first uncoated portion coupling portions 144b may be formed to have substantially the same width and thickness.

Although not shown in the drawing, a plurality of bridge portions 144d may be provided. Each of the plurality of bridge portions 144d may be provided between a pair of first uncoated portion coupling portions 144b adjacent to each other. The plurality of bridge portions 144d may be provided at substantially regular intervals from each other in the extending direction of the edge portion 144a. The distance from each of the plurality of bridge portions 144d to one of the pair of first uncoated portion coupling portions 144b adjacent to each other in the extending direction of the edge portion 144a may be substantially equal to the distance from each of the plurality of bridge portions 144d. The distance from each of the two first uncoated portion coupling portions 144b to the other one of the pair of first uncoated portion coupling portions 144b.

In the case where a plurality of first uncoated portion coupling portions 144b and/or bridge portions 144d are provided as described above, if the distance between the first uncoated portion coupling portions 144b and/or the distance between the bridge portions 144d and/or the distance between the first uncoated part coupling part 144b and the bridge part 144d is formed uniformly, then the current flowing from the first uncoated part coupling part 144b to the bridge part 144d or from the bridge part can be smoothly and uniformly formed. The current flowing from the portion 144d to the first uncoated portion coupling portion 144b.

Meanwhile, the first current collector 144 and the bent surface area (F ₁ ) of the uncoated portion 146a may be coupled by welding. In this case, for example, laser welding, ultrasonic welding, spot welding, etc. can be applied. Preferably, the welding area may overlap by more than 50% with the uniform stacking area (W ₁ ) of the bent surface area (F ₁ ).

The bridge portion 144d may include a groove portion N formed to locally reduce the cross-sectional area of the bridge portion 144d. The cross-sectional area of the slotted portion N may be adjusted, for example, by locally reducing the width and/or thickness of the bridge portion 144d. When the groove portion N is provided, the resistance in the region where the groove portion N is formed increases, thereby achieving rapid current interruption when an overcurrent occurs.

The grooved portion N is preferably provided in an area corresponding to a uniform area of overlapping layer numbers of the electrode assembly 110 to prevent foreign matter generated during rupture from flowing into the electrode assembly 110 . This is because, in this area, the number of overlapping layers of the section of the uncoated portion 146a is maintained at a maximum, and therefore the overlapping section can be used as a mask. For example, the grooved portion N may be provided in a region where the number of stacked layers of the uncoated portion 146a is the largest in the uniform stacking number region.

FIG. 13 is a top plan view showing the structure of the second current collector 176 according to one embodiment of the present disclosure.

Referring to FIG. 13 , a second current collector 176 is disposed below the electrode assembly 110 . In addition, the second current collector 176 may be configured to electrically connect the uncoated portion 146b of the electrode assembly 110 and the battery case 171. The second current collector 176 is made of a conductive metal material and is electrically connected to the uncoated portion 146b. In addition, the second current collector 176 is electrically connected to the battery case 171 . The second current collector 176 may be interposed and fixed between the inner surface of the battery case 171 and the first gasket 178b. Specifically, the second current collector 176 may be interposed between the lower surface of the crimp portion 180 of the battery case 171 and the first gasket 178b. However, the present disclosure is not limited thereto, and the second current collector 176 may be welded to the inner wall surface of the battery case 171 in a region where the crimp portion 180 is not formed.

The second current collector 176 may include: a support portion 176a disposed below the electrode assembly 110; and a second uncoated portion coupling portion 176b approximately along a radial direction of the electrode assembly 110 a bent surface region ( _F2 ) extending from the support portion 176a and coupled to the uncoated portion 146b; and a housing coupling portion 176c extending from the support portion 176a approximately in the radial direction of the electrode assembly 110 and coupled to the inner surface of the battery case 171 . The second uncoated portion coupling portion 176b and the housing coupling portion 176c are indirectly connected 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 disclosure, the possibility of damaging the coupling portion of the second current collector 176 and the electrode assembly 110 and the coupling portion of the second current collector 176 and the battery case 171 can be minimized. However, the second current collector 176 of the present disclosure is not limited to a structure in which the second uncoated portion coupling portion 176b and the case coupling portion 176c are only indirectly connected. For example, the second current collector 176 may have a structure that does not include the support portion 176a for indirectly connecting the second uncoated portion coupling portion 176b and the case coupling portion 176c and/or the uncoated portion 146b and the case coupling portion 176c Structures that are directly connected to each other.

The support portion 176a and the second uncoated portion coupling portion 176b are provided below the electrode assembly 110. The second uncoated portion coupling portion 176b is coupled to the bent surface area (F ₂ ) of the uncoated portion 146b. In addition to the second uncoated portion coupling portion 176b, the support portion 176a may be coupled to the uncoated portion 146b. The second uncoated portion coupling portion 176b and the uncoated portion 146b may be coupled by welding. When the bead portion 180 is formed on the battery case 171 , the support portion 176 a and the second uncoated portion coupling portion 176 b are located at a higher position than the bead portion 180 .

The support portion 176 a has a current collector hole 176 d formed at a position corresponding to the hole formed at the core C of the electrode assembly 110 . The core C of the electrode assembly 110 and the current collector hole 176d communicated with each other may serve as a passage for inserting a welding rod between the terminal 172 and the terminal coupling portion 144c of the first current collector 144 or for irradiating a laser beam. The diameter of the current collector hole 176d may be substantially equal to or larger than the diameter of the hole formed in the core C of the electrode assembly 110. When the plurality of second uncoated portion coupling portions 176b are provided, the plurality of second uncoated portion coupling portions 176b may have an approximately radial extension from the support portion 176a of the second current collector 176 toward the side wall of the battery case 171 shape. A plurality of second uncoated portion coupling portions 176b may be positioned spaced apart from each other along the periphery of the support portion 176a.

Multiple housing couplings 176c may be provided. In this case, the plurality of case coupling portions 176 c may have a shape extending approximately radially from the center of the second current collector 176 toward the side wall of the battery case 171 . Therefore, electrical connections between the second current collector 176 and the battery case 171 can be made at multiple points. Since connections for electrical connection are made at multiple points, the connection area can be maximized, thereby minimizing resistance. A plurality of housing coupling portions 176c may be positioned spaced apart from each other along the periphery of the support portion 176a. At least one housing coupling portion 176c may be positioned between second uncoated portion coupling portions 176b adjacent to each other. The plurality of case coupling portions 176c may be coupled to, for example, the bead portion 180 in the inner surface of the battery case 171. The housing coupling portion 176c may be coupled to the lower surface of the crimp portion 180, particularly by welding. Welding may be performed using, for example, laser welding, ultrasonic welding or spot welding. By welding the case coupling portion 176c to the crimp portion 180 in this manner, the resistance level of the cylindrical battery 200 can be limited to approximately 4 milliohms or less. In addition, since the lower surface of the crimp portion 180 has a shape extending in a direction approximately parallel to the upper surface of the battery case 171 (ie, in a direction approximately perpendicular to the side wall of the battery case 171), and the case coupling portion 176c also has a shape extending in the same direction (ie, in the radial direction and the circumferential direction), so the housing coupling portion 176c can stably contact the curling portion 180. In addition, since the housing coupling portion 176c stably contacts the flat portion of the crimp portion 180, the two components can be smoothly welded, thereby improving the coupling force between the two components and reducing the increase in resistance at the coupling portion. minimize.

The case coupling part 176c may include a contact part 176e coupled to the inner surface of the battery case 171 and a connection part 176f for connecting the support part 176a and the contact part 176e.

The contact portion 176e is coupled to the inner surface of the battery case 171. In the case where the bead portion 180 is formed on the battery case 171, the contact portion 176e may be coupled to the bead portion 180 as described above. More specifically, the contact portion 176e may be electrically coupled to a flat portion formed at the lower surface of the crimp portion 180 on the battery case 171, and may be interposed between the lower surface of the crimp portion 180 and the first gasket 178b . In this case, in order to stabilize contact and coupling, the contact portion 176e may have a shape extending a predetermined length on the crimp portion 180 in the circumferential direction of the battery case 171.

Meanwhile, the maximum distance in the radial direction of the electrode assembly 110 from the center of the second current collector 176 to the end of the second uncoated portion coupling portion 176b is preferably equal to or smaller than the battery case 171 when the crimp portion 180 is formed. The inner diameter in the area is the minimum inner diameter of the battery case 171. This is to prevent the second current collector 176 from being interfered by the crimp portion 180 during the sizing process of compressing the battery case 171 in the height direction, thereby preventing the electrode assembly 110 from being pressed by the second current collector 176 .

The second uncoated portion coupling portion 176b includes a hole 176g. Holes 176g can serve as channels through which electrolyte can move. The welding pattern 176h formed by the welding between the second uncoated portion coupling portion 176b and the bent surface area ( _F2 ) may have a structure extending in the radial direction of the electrode assembly 110. The weld pattern 176h may be a line pattern or a dot array pattern.

An advantage of the cylindrical battery 200 according to one embodiment of the present disclosure is that electrical connections can be made at the upper portion thereof.

FIG. 14 is a top plan view showing a state in which a plurality of cylindrical batteries 200 are electrically connected, and FIG. 15 is a partial enlarged view of FIG. 14 .

Referring to FIGS. 14 and 15 , a plurality of cylindrical batteries 200 may be connected in series and parallel at an upper portion of the cylindrical batteries 200 using a bus bar 210 . The number of cylindrical batteries 200 may be increased or decreased in consideration of the capacity of the battery pack.

In each cylindrical battery 200, the terminal 172 may have a positive polarity, and the flat surface 171a of the battery case 171 around the terminal 172 may have a negative polarity, or vice versa.

Preferably, the plurality of cylindrical batteries 200 may be arranged in columns and rows. Columns are arranged vertically relative to the drawing, and rows are arranged left-right relative to the drawing. Furthermore, to maximize space efficiency, the cylindrical cells 200 can be arranged in the tightest package structure. When an equilateral triangle is formed by connecting the centers of the terminals 172 exposed outside the battery case 171 to each other, a tight packaging structure is formed. Preferably, the bus bar 210 connects the cylindrical batteries 200 arranged in the same column to each other in parallel, and connects the cylindrical batteries 200 arranged in two adjacent columns to each other in series.

Preferably, the bus bar 210 may include a body portion 211 for series and parallel connection, a plurality of first bus bar terminals 212 and a plurality of second bus bar terminals 213. Body portion 211 may extend along the column of cylindrical cells 200 between adjacent terminals 172 . Alternatively, the body portion 211 may extend along the rows of the cylindrical batteries 1 and may be regularly bent in a zigzag shape.

The plurality of first bus bar terminals 212 may extend from one side of the body part 211 and may be electrically coupled to the terminals 172 of the cylindrical battery 200 positioned in the extension direction. The electrical connection between the first bus bar terminal 212 and the terminal 172 can be achieved by laser welding, ultrasonic welding, or the like.

The plurality of second bus bar terminals 213 may extend from the other side of the body part 211 and may be electrically coupled to the flat surface 171a located around the terminals 172 positioned in the extending direction. The electrical connection between the second bus bar terminal 213 and the flat surface 171a may be performed by laser welding, ultrasonic welding, or the like.

Preferably, the body part 211, the plurality of first bus bar terminals 212 and the plurality of second bus bar terminals 213 may be made of one conductive metal plate. The metal plate may be, for example, an aluminum plate or a copper plate, but the present disclosure is not limited thereto. In a modified example, 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 coupled to each other by welding or the like.

The cylindrical battery 200 of the present disclosure as described above has a structure in which the current path length is minimized by enlarging the welding area by means of the bent surface areas _F1 and _F2 , multiplexing the current path by means of the second current collector 176 etc. to minimize the resistance. The AC resistance of the cylindrical battery 200 may be 0.5 milliohm to 4 milliohm (preferably 1 milliohm to 4 milliohm), suitable for fast charging.

In the cylindrical battery 200 according to the present disclosure, since the terminal 172 with positive polarity and the flat surface 171 a with negative polarity are located in the same direction, it is easy to electrically connect the cylindrical battery 200 using the bus bar 210 .

In addition, since the terminal 172 of the cylindrical battery 200 and the flat surface 171 a around the terminal 172 have a large area, the connection area of the bus bar 210 can be sufficiently ensured to sufficiently reduce the resistance of the battery pack including the cylindrical battery 200 .

The cylindrical battery according to the above embodiment (modification) can be used to manufacture a battery pack.

FIG. 16 is a diagram schematically showing a battery pack according to one embodiment of the present disclosure.

Referring to FIG. 16 , a battery pack 300 according to one embodiment of the present disclosure includes: an aggregate in which cylindrical cells 301 are electrically connected; and a battery pack case 302 for accommodating the aggregate. The cylindrical battery 301 may be any one of the batteries according to the above embodiments (modifications). In the drawing, components such as bus bars, cooling units, external terminals, etc. for electrical connection of the cylindrical battery 301 are not depicted for convenience of illustration.

The battery pack 300 can be installed in a vehicle. The vehicle may be, for example, an electric vehicle, a hybrid electric vehicle or a plug-in hybrid vehicle. Vehicles include four-wheeled vehicles or two-wheeled vehicles.

FIG. 17 is a diagram schematically showing a vehicle including the battery pack 300 of FIG. 16 .

Referring to FIG. 17 , a vehicle V according to one embodiment of the present invention includes a battery pack 300 according to one embodiment of the present disclosure. According to one embodiment of the present disclosure, the vehicle V operates by receiving power from the battery pack 300 .

According to one embodiment of the present disclosure, when bending the uncoated portions exposed at both ends of the electrode assembly, it can be achieved by fully ensuring that the uncoated portions overlap into an area of more than 10 layers in the radial direction of the electrode assembly. Prevents the separator or active material layer from being damaged when welding the current collector.

According to yet another embodiment of the present disclosure, since the structure of the uncoated portion adjacent to the core of the electrode assembly is improved, it is possible to prevent the cavity in the core of the electrode assembly from being blocked when the uncoated portion is bent. Therefore, the electrolyte injection process and the process of welding the battery case and the current collector can be easily performed.

According to yet another embodiment of the present disclosure, since the bent surface area of the uncoated portion is directly welded to the current collector instead of the strip-shaped electrode tab, it is possible to provide an electrode assembly with improved energy density and reduced resistance.

According to yet another embodiment of the present disclosure, a cylindrical battery having low internal resistance and improved welding strength between a current collector and an uncoated portion, and a battery pack and a vehicle including the cylindrical battery can be provided Structure.

The present disclosure has been described in detail. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the present disclosure, are given by way of illustration only since this disclosure will, based on this detailed description, be apparent to those skilled in the art. Various changes and variations within the scope will become apparent.

Claims (78)

1. An electrode assembly in which a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode are wound based on an axis to define a core and an outer circumference, wherein the first electrode includes an uncoated portion exposed outside the separator at a long side end thereof and along a winding axis direction of the electrode assembly, and A portion of the uncoated portion is bent in a radial direction of the electrode assembly to form a bent surface area including overlapping layers of the uncoated portion, and in a local area of the bent surface area , in the direction of the winding axis of the electrode assembly, the number of stacked layers of the uncoated portion is 10 or more. 2. The electrode assembly according to claim 1, Wherein, when the total number of winding turns of the first electrode is defined as n ₁ , and the value obtained by dividing the winding turn index k at the k-th winding turn position by the total number of winding turns n ₁ is defined When the relative radial position R _1,k of the winding turn index k, based on the relative radial position area in which the uncoated part is bent, the number of stacked layers of the uncoated part is satisfied to be 10 or more The length ratio of the radial zone of the condition R _{1, k} is 30% or more, where k is a natural number from 1 to n ₁ . 3. The electrode assembly according to claim 2, Wherein, based on the relative radial position area in which the uncoated portion is bent, all the radial areas of R _1,k satisfying the condition that the number of stacked layers of the uncoated portion is 10 or more The length ratio is 30% to 85%. 4. The electrode assembly according to claim 1, wherein the second electrode includes an uncoated portion exposed outside the separator at a long side end thereof and along the winding axis direction of the electrode assembly, and A portion of the uncoated portion is bent along the radial direction of the electrode assembly to form a bent surface area including an overlapping layer of the uncoated portion, and a portion of the bent surface area In the region, in the direction of the winding axis of the electrode assembly, the number of stacked layers of the uncoated portion is 10 or more. 5. The electrode assembly according to claim 4, Wherein, when the total number of winding turns of the second electrode is defined as n ₂ , and the value obtained by dividing the winding turn index k at the k-th winding turn position by the total number of winding turns n ₂ is defined When it is the relative radial position R _2,k of the winding turn index k, based on the relative radial position area in which the uncoated part is bent, the number of stacked layers of the uncoated part is satisfied to be 10 or more The length ratio of the radial zone of the condition R2 _,k is more than 30%, where k is a natural number from 1 to _n2 . 6. The electrode assembly according to claim 5, Wherein, based on the relative radial position area in which the uncoated portion is bent, the length ratio of the radial area of R _2,k that satisfies the condition that the number of stacked layers of the uncoated portion is 10 or more is: 30% to 85%. 7. The electrode assembly according to claim 2, Wherein, in the winding structure of the first electrode, from the relative radial position R _1,1 of the first winding turn to the preset first relative radial position R _1,k of the k ^*th winding turn The height of the uncoated portion of the area _* is smaller than the height of the uncoated portion of the area from the relative radial position R _1,k*+1 of the k*+1th winding turn to the relative radial position 1 high. 8. The electrode assembly according to claim 2, Wherein, in the winding structure of the first electrode, from the relative radial position R _1,1 of the first winding turn to the preset first relative radial position R _1,k of the k ^*th winding turn The height of the uncoated portion of the area _* is smaller than the height of the bent surface area formed by the overlap of the bent uncoated portions. 9. The electrode assembly according to claim 2, Wherein, in the winding structure of the first electrode, the area from the relative radial position R _1,1 of the first winding turn to the first relative radial position R _1,k* of the k ^* th winding turn The uncoated portion is not bent toward the core of the electrode assembly. 10. The electrode assembly according to claim 5, Wherein, in the winding structure of the second electrode, from the relative radial position R _2,1 of the first winding turn to the preset first relative radial position R _2,k of the k ^* th winding turn The height of the uncoated portion of the area _* is smaller than the height of the uncoated portion of the area from the relative radial position R _2,k*+1 of the k*+1th winding turn to the relative radial position 1 high. 11. The electrode assembly according to claim 5, Wherein, in the winding structure of the second electrode, from the relative radial position R _2,1 of the first winding turn to the preset first relative radial position R _2,k of the k ^* th winding turn The height of the uncoated portion of the area _* is smaller than the height of the bent surface area formed by overlapping the bent uncoated portions. 12. The electrode assembly according to claim 5, Wherein, in the winding structure of the second electrode, from the relative radial position R _2,1 of the first winding turn to the preset first relative radial position R _2,k of the k ^* th winding turn The uncoated portion of the _* area is not bent toward the core of the electrode assembly. 13. The electrode assembly according to claim 1 or 4, Wherein, the uncoated portion of the first electrode or the second electrode is divided into a plurality of sections that can be independently bent. 14. The electrode assembly according to claim 13, wherein each of the plurality of sections has a geometric shape having a bend line as a base, and The geometric shape is formed by connecting one or more straight lines, one or more curves, or a combination thereof. 15. The electrode assembly according to claim 14, Wherein the geometric shape has a width that gradually or continuously decreases from the base to the top. 16. The electrode assembly according to claim 15, Wherein, the lower inner angle of the geometric shape between the base and the side intersecting the base is 60 to 85 degrees. 17. The electrode assembly according to claim 16, Wherein, the lower inner angles of the plurality of sections gradually increase or gradually increase in a direction parallel to the winding direction of the electrode assembly. 18. The electrode assembly according to claim 14, wherein each of the plurality of sections has a geometric shape having a bend line as a base, and When the radius of the winding turn provided with the segment is r based on the core center of the electrode assembly, the arc length of the lower part of the winding turn corresponding to the segment is L _arc , and assuming that the radius is When the lower internal angle of the sides of a pair of adjacent sections in the winding turn r is θ _assumption , the actual lower internal angle θ _real of the adjacent pair of sections satisfies the following formula: θ _real >θ _assumption θ _assumption =90°-360°*(L _arc /2πr)*0.5. 19. The electrode assembly according to claim 18, Wherein, based on the core center of the electrode assembly, a circumferential angle corresponding to the arc length L _arc of the winding turns corresponding to the lower part of the section is 45 degrees or less. 20. The electrode assembly according to claim 18, Wherein, when the formula θ _real /θ _assumptoin -1 is used to define the overlap ratio of adjacently arranged sections in the winding turns of the radius r based on the core center of the electrode assembly, the intersection of the sections The overlap ratio is greater than 0 and equal to or less than 0.05. 21. The electrode assembly of claim 14, Wherein, when a virtual circle passing through a pair of adjacently arranged segments in a winding turn of radius r based on the core center of the electrode assembly is drawn, a pair of arcs passing through each segment intersect each other. Stack. 22. The electrode assembly according to claim 21, Wherein, when the ratio of the length of the overlapping arc and the length of the arc passing through each segment is defined as the overlap ratio, the overlap ratio of the segment is greater than 0 and equal to or less than 0.05. 23. The electrode assembly of claim 2, Wherein, in the winding structure of the first electrode, the area from the relative radial position R _1,1 of the first winding turn to the first relative radial position R _1,k* of the k ^* th winding turn The height of the uncoated portion is less than the height of the uncoated portion in the area from the relative radial position R _1,k*+1 of the k*+1th winding turn to the relative radial position 1, and Do not bend towards the core. 24. The electrode assembly according to claim 23, Wherein, the length of the first electrode corresponding to the area from the relative radial position R _1,1 to the first relative radial position R _1,k* is the same as the length of the first electrode corresponding to the area from the relative radial position R 1,1 to the first relative radial position R 1,k*. The ratio of the length of the area from the relative radial position R _1,k*+1 to the relative radial position 1 is 1% to 30%. 25. The electrode assembly of claim 2, Wherein, in the winding structure of the first electrode, the bending length fd 1,k of the uncoated portion at the relative radial position R _1,k*+1 of the k*+1th winding turn _{is *+1} is shorter than the radial length from the relative radial position R _1,1 of the 1st winding turn to the relative radial position R _1,k* of the k*th winding turn. 26. The electrode assembly of claim 2, Wherein, in the wound structure of the first electrode, when the radius of the core of the electrode assembly is defined as r _c , the area from the center of the core to 0.90 r _c is not located from the k*th The bend of the uncoated portion in the region of the relative radial position R _1,k*+1 of the +1 winding turn blocks the relative radial position 1 . 27. The electrode assembly of claim 26, Wherein, the bending length fd _{1,k*+1 of the uncoated portion at the relative radial position R 1 ,k*+1 of the k*+1th winding turn} , the radius _rc of the core and The distance d _{1 ,k*+1 from the center of the electrode assembly to the relative radial position R 1,} k*+1 satisfies the following formula: fd _1,k*+1 +0.9*r _c ≤d _1,k*+1 . 28. The electrode assembly of claim 5, Wherein, in the winding structure of the second electrode, from the relative radial position R _2,1 of the first winding turn to the preset first relative radial position R _2,k of the k ^* th winding turn The height of the uncoated portion of the area _* is smaller than the height of the uncoated portion of the area from the relative radial position R _2,k*+1 of the k*+1th winding turn to the relative radial position 1 height and does not bend towards the core. 29. The electrode assembly of claim 28, Wherein, the length of the second electrode corresponding to the area from the relative radial position R _2,1 to the first relative radial position R _2,k* is the same as the length of the second electrode corresponding to the area from the relative radial position R 2,1 to the first relative radial position R 2,k*. The ratio of the length of the area from the relative radial position R _2,k*+1 to the relative radial position 1 is 1% to 30%. 30. The electrode assembly of claim 5, Wherein, in the winding structure of the second electrode, the bending length fd 2,k of the uncoated portion at the relative radial position R _2,k*+1 of the k*+1th winding turn _{is *+1} is shorter than the radial length from the relative radial position R _2,1 of the 1st winding turn to the relative radial position R _1,k* of the k*th winding turn. 31. The electrode assembly of claim 5, Wherein, in the wound structure of the second electrode, when the radius of the core of the electrode assembly is defined as r _c , the area from the center of the core to 0.90 r _c is not covered by the second electrode The bending portion of the uncoated portion located in the area from the relative radial position R _2,k*+1 of the k*+1th winding turn to the relative radial position 1 blocks. 32. The electrode assembly of claim 31, Wherein, the bending length fd _{2,k*+1 of the uncoated portion at the relative radial position R 2 ,k*+1 of the k*+1th} winding turn, the radius r of the core _c and the distance d 2 _{,k*+1 from the center of the electrode assembly to the relative radial position R 2 ,k*+1} satisfy the following formula: fd _2,k*+1 +0.9*r _c ≤d _2,k*+1 . 33. The electrode assembly of claim 2, Wherein, in the winding structure of the first electrode, from the relative radial position R _{1,k*+1 of the k*+1th} winding turn to the preset second relative radial position of the k@th winding turn The uncoated portion of the area toward the position R _1,k@ is divided into a plurality of sections, the heights of which gradually increase or gradually increase in a direction parallel to the winding direction. 34. The electrode assembly of claim 33, Wherein, the radial length of the area from the relative radial position R _1,k*+1 to the second relative radial position R _1,k@ is the same as the winding structure of the first electrode except for the The ratio of the radii outside the core of the electrode assembly ranges from 1% to 56%. 35. The electrode assembly of claim 2, Wherein, in the winding structure of the first electrode, the unsettled area from the preset relative radial position R1 _{,k@+1 of the k@+1th winding} turn to the relative radial position 1 The coating part is divided into a plurality of sections, and the heights of the plurality of sections are substantially the same as the height from the relative radial position R _1,k@+1 to the relative radial position 1 . 36. The electrode assembly of claim 5, Wherein, in the winding structure of the second electrode, from the relative radial position R _{2,k*+1 of the k*+1th} winding turn to the preset second relative radial position of the k@th winding turn The uncoated portion of the area toward position R _2,k@ is divided into a plurality of sections, the heights of which gradually increase or gradually increase in a direction parallel to the winding direction. 37. The electrode assembly of claim 36, Wherein, the radial length of the area from the relative radial position R _2,k*+1 to the second relative radial position R _2,k@ is the same as the winding structure of the second electrode except for the The ratio of the radii outside the core of the electrode assembly ranges from 1% to 56%. 38. The electrode assembly of claim 5, Wherein, in the winding structure of the second electrode, the area of the second electrode from the relative radial position R2 _{,k@+1 of the k@+1th winding turn} to the relative radial position 1 The uncoated portion is divided into a plurality of sections, and the heights of the plurality of sections are approximately the same as the height from the relative radial position R _2,k@+1 to the relative radial position 1 . 39. The electrode assembly of claim 1, Wherein, in the rolled structure of the first electrode, the uncoated portion bent along the radial direction of the electrode assembly is divided into a plurality of sections 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 sections gradually or gradually increases in a direction parallel to the winding direction, individually or in groups. . 40. The electrode assembly of claim 4, Wherein, in the wound structure of the second electrode, the uncoated portion bent along the radial direction of the electrode assembly is divided into a plurality of sections 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 sections gradually or gradually increases in a direction parallel to the winding direction, individually or in groups. . 41. The electrode assembly of claim 13, Wherein, each of the plurality of sections satisfies at least one of the following conditions: a width condition of 1 mm to 11 mm along the winding direction; a height condition of 2 mm to 10 mm along the winding axis direction; and a separation spacing condition of 0.05mm to 1mm along the winding direction. 42. The electrode assembly of claim 13, wherein cutting grooves are inserted between the plurality of sections, and A predetermined gap is provided between the bottom of the cutting groove and the active material layer of the first electrode or the second electrode. 43. The electrode assembly of claim 32, Wherein, the gap has a length of 0.2mm to 4mm. 44. The electrode assembly of claim 13, Wherein, the plurality of sections form a plurality of section groups along the winding direction of the electrode assembly, and the width of sections belonging to the same section group in the winding direction, the winding axis direction At least one aspect of the height and the separation pitch in the winding direction is substantially the same as each other. 45. The electrode assembly of claim 44, Wherein, the sections belonging to the same section group are configured such that at least one of the width in the winding direction, the height in the winding axis direction and the separation pitch in the winding direction is along the same line as One direction parallel to the winding direction of the electrode assembly gradually or gradually increases. 46. The electrode assembly of claim 44, Wherein, at least a part of the plurality of segment groups are disposed at the same winding turn of the electrode assembly. 47. The electrode assembly of claim 1, wherein the bent surface area formed by the uncoated portion of the first electrode includes an increased stacking number area and a uniform stacking number from the outer periphery of the electrode assembly to the core of the electrode assembly district, The stacking number increasing region is defined as a region in which the stacking number of the uncoated portion increases toward the core of the electrode assembly, and the stacking number uniform region is defined as a region starting from the uncoated portion. The area from the radial position where the number of stacked layers stops increasing to the radial position where the uncoated portion begins to bend, and The ratio of the radial length of the uniform stacking area to the radial length of the winding turns from the beginning of the bending of the uncoated portion to the end of the bending of the uncoated portion is 30% or more. 48. The electrode assembly of claim 5, wherein the bent surface area formed by the uncoated portion of the second electrode includes an increased stacking number area and a uniform stacking number from the outer periphery of the electrode assembly to the core of the electrode assembly district, The stacking number increasing region is defined as a region in which the stacking number of the uncoated portion increases toward the core of the electrode assembly, and the stacking number uniform region is defined as a region starting from the uncoated portion. The area from the radial position where the number of stacked layers stops increasing to the radial position where the uncoated portion begins to bend, and The ratio of the radial length of the uniform stacking area to the radial length of the winding turns from the beginning of the bending of the uncoated portion to the end of the bending of the uncoated portion is 30% or more. 49. The electrode assembly of claim 4, Wherein, the thickness of the first electrode and the second electrode is 80 μm to 250 μm, and The spacing between the uncoated portions at adjacent winding turns in the radial direction of the electrode assembly is 200 μm to 500 μm. 50. The electrode assembly of claim 1, Wherein, the uncoated portion of the first electrode has a thickness of 10 μm to 25 μm. 51. The electrode assembly of claim 4, Wherein, the uncoated portion of the second electrode has a thickness of 5 μm to 20 μm. 52. The electrode assembly of claim 1, Wherein, in the partial area of the bent surface area formed by the uncoated portion of the first electrode, a total stack thickness of overlapping layers of the uncoated portion is 100 μm to 975 μm. 53. The electrode assembly of claim 52, Wherein, the uncoated portion of the first electrode is divided into a plurality of sections that can be bent independently, and the first electrode includes a height-variable region of the section and a height-uniform region of the section. a highly uniform region, and in a region of the bent surface region formed by bending a section included in the highly uniform region along the radial direction of the electrode assembly, the bent surface region The ratio of the stack thickness of the uncoated portion to the height of the section is 1.0% to 16.3%. 54. The electrode assembly of claim 4, Wherein, in the partial area of the bent surface area formed by the uncoated portion of the second electrode, a total stack thickness of overlapping layers of the uncoated portion is 50 μm to 780 μm. 55. The electrode assembly of claim 54, Wherein, the uncoated portion of the second electrode is divided into a plurality of sections that can be bent independently, and the second electrode includes a height-variable region of the section and a height-uniform region of the section. a highly uniform region, and in a region of the bent surface region formed by bending a section included in the highly uniform region along the radial direction of the electrode assembly, the bent surface region The ratio of the stack thickness of the uncoated portion to the height of the section is 0.5% to 13.0%. 56. An electrode assembly in which a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode are wound based on an axis to define a core and a periphery, wherein the first electrode includes a first uncoated portion exposed outside the separator at a long side end thereof and along a winding axis direction of the electrode assembly, and A portion of the first uncoated portion is bent along a radial direction of the electrode assembly to form a first bent surface area, and in a local area of the first bent surface area, the first uncoated portion The stack thickness of the coated part is 100 μm to 975 μm. 57. The electrode assembly of claim 56, Wherein, the first uncoated portion of the first electrode is divided into a plurality of sections that can be bent independently, and the first electrode includes a height-variable region of the section and a height of the section. a uniform highly uniform region, and in a region of the bent surface region formed by bending a section included in the highly uniform region along the radial direction of the electrode assembly, the bending The ratio of the stack thickness of the uncoated portion of the surface area to the height of the section is from 1.0% to 16.3%. 58. The electrode assembly of claim 56, wherein the second electrode includes a second uncoated portion exposed outside the separator at a long side end thereof and along the winding axis direction of the electrode assembly, and a portion of the second uncoated portion is bent along the radial direction of the electrode assembly to form a second bent surface area, and In the local area of the second bent surface area, the stack thickness of the second uncoated portion is 50 μm to 780 μm. 59. The electrode assembly of claim 58, Wherein, the second uncoated portion of the second electrode is divided into a plurality of sections that can be bent independently, and the second electrode includes a height-variable region of the section and a height of the section. a uniform highly uniform region, and in a region of the bent surface region formed by bending a section included in the highly uniform region along the radial direction of the electrode assembly, the bending The ratio of the stack thickness of the uncoated portion of the surface area to the height of the section is from 0.5% to 13.0%. 60. A battery, said battery comprising: An electrode assembly in which a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode are wound based on an axis to define a core and a periphery, wherein the At least one of the first electrode and the second electrode includes an uncoated portion exposed outside the separator at a long side end thereof and in a winding axis direction of the electrode assembly, and the uncoated portion At least a portion of the coated portion is bent along the radial direction of the electrode assembly to form a bent surface area, and in a local area of the bent surface area, the number of stacked layers of the uncoated portion is 10 or more; a battery case configured to house the electrode assembly and electrically connected to one of the first electrode and the second electrode to have a first polarity; a sealing body configured to seal the open end of the battery housing; a terminal electrically connected to the other of the first electrode and the second electrode to have a second polarity and configured to have a surface exposed to the outside; and a current collector welded to the bent surface region and electrically connected to any of the battery case and the terminal, Wherein, the welding area of the current collector overlaps the bent surface area where the number of stacked layers of the uncoated portion is 10 or more. 61. The battery of claim 60, wherein the first electrode includes a first uncoated portion exposed outside the separator at a long side thereof and along a winding axis direction of the electrode assembly; and When the total number of winding turns of the first electrode is defined as n ₁ , and the value obtained by dividing the winding turn index k at the k-th winding turn position by the total number of winding turns n ₁ is defined as When the relative radial position R _{1,k of the winding turn index k} , based on the relative radial position area in which the first uncoated part is bent, the number of stacked layers of the first uncoated part is: The length ratio of the radial region of R _1,k under the condition of 10 or more, where k is a natural number from 1 to n ₁ , is 30% or more. 62. The battery of claim 60, wherein the second electrode includes a second uncoated portion exposed outside the separator at a long side thereof and along the winding axis direction of the electrode assembly, and When the total number of winding turns of the second electrode is defined as n ₂ , and the value obtained by dividing the winding turn index k at the k-th winding turn position by the total number of winding turns n ₂ is defined as When the relative radial position R _{2,k of the winding turn index k} , based on the relative radial position area in which the second uncoated part is bent, the number of stacked layers of the second uncoated part is: The length ratio of the radial region of R _{2 and k} under the condition of 10 or more, where k is a natural number from 1 to n ₂ , is 30% or more. 63. The battery of claim 60, Wherein, the welding area of the current collector overlaps by more than 50% with the bent surface area in which the number of stacked layers of the uncoated portion is more than 10. 64. The battery of claim 63, Wherein, the welding strength of the current collector is in a range of 2kgf/ ^cm2 or above. 65. The battery of claim 60, Wherein, the welding areas are spaced apart by a distance of more than 4 mm based on the core center of the electrode assembly and less than 50% of the radius of the electrode assembly. 66. A battery, said battery comprising: An electrode assembly in which a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode are wound based on an axis to define a core and a periphery, wherein the The first electrode includes a first uncoated portion exposed outside the separator at a long side end thereof and along the winding axis direction of the electrode assembly, and a portion of the first uncoated portion extends along the direction of the winding axis of the electrode assembly. The electrode assembly is bent in a radial direction to form a first bent surface area, and in a local area of the first bent surface area, the stack thickness of the first uncoated portion is 100 μm to 975 μm; a battery case configured to house the electrode assembly and electrically connected to one of the first electrode and the second electrode to have a first polarity; a sealing body configured to seal the open end of the battery housing; a terminal electrically connected to the other of the first electrode and the second electrode to have a second polarity and configured to have a surface exposed to the outside; and a first current collector welded to the first bent surface region and electrically connected to any of the battery case and the terminal, Wherein, the welding area of the first current collector overlaps the local area of the first uncoated portion in the first bending surface area where the stack thickness is 100 μm to 975 μm. 67. The battery of claim 66, Wherein, the first uncoated portion of the first electrode is divided into a plurality of sections that can be bent independently, and the first electrode includes a height-variable region with a variable height of the section and a height of the section. a uniform highly uniform region, and in a region in the first bent surface region formed by bending a section included in the highly uniform region along the radial direction of the electrode assembly, the The ratio of the stack thickness of the uncoated portion of the first bent surface area to the height of the section is from 1.0% to 16.3%. 68. The battery of claim 66, Wherein, the welding strength of the first current collector is in a range of 2kgf/cm ^or above. 69. The battery of claim 66, Wherein, the second electrode includes a second uncoated portion at a long side end thereof and exposed outside the separator along the winding axis direction of the electrode assembly, and the second uncoated portion A portion of the electrode assembly is bent along the radial direction to form a second bending surface area, and in a local area of the second bending surface area, the stack thickness of the second uncoated portion 50μm to 780μm, the battery includes a second current collector welded to the second bent surface region and electrically connected to any of the battery case and the terminal, and The welding area of the second current collector overlaps the local area of the second bent surface area where the stack thickness of the second uncoated portion is 50 μm to 780 μm. 70. The battery of claim 69, Wherein, the second uncoated portion of the second electrode is divided into a plurality of sections that can be bent independently, and the second electrode includes a height-variable region of the section and a height of the section. a uniform highly uniform region, and in a region in the second bent surface region formed by bending a section included in the highly uniform region along the radial direction of the electrode assembly, the The ratio of the stack thickness of the uncoated portion of the second bent surface area to the height of the section is from 0.5% to 13.0%. 71. The battery of claim 69, Wherein, the welding strength of the second current collector is in a range of 2kgf/cm2 ^or above. 72. The battery of claim 66, Wherein, the welding area of the first current collector overlaps by 50% with the local area of the first bending surface area where the stack thickness of the first uncoated portion is 100 μm to 975 μm. above. 73. The battery of claim 69, Wherein, the welding area of the second current collector overlaps by 50% with the local area of the second bending surface area where the stack thickness of the second uncoated portion is 50 μm to 780 μm. above. 74. The battery of claim 69, wherein the welding zone of the first current collector and the welding zone of the second current collector are substantially equally spaced from a core center of the electrode assembly in the radial direction of the electrode assembly The distance the location extends. 75. The battery of claim 74, Wherein, 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. 76. The battery of claim 66, Wherein, the battery has a resistance of less than 4 milliohms. 77. A battery pack comprising a cell according to any one of claims 60 to 76. 78. A vehicle including the battery pack of claim 77.