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

Abstract

The present invention discloses an electrode assembly, a battery, a battery pack including the same, and an automobile. At least one of a first electrode and a second electrode of an electrode assembly includes an uncoated portion at a long side end thereof that is exposed to the outside of a separator along a longitudinal direction of the electrode assembly, and at least a portion of the uncoated portion is bent in a radial direction of the electrode assembly to form a bent surface, and the bent surface includes an area along the radial direction where the number of overlapping layers of the uncoated portion is maintained at a standard number. A welding area of ​​a current collector plate welded to the bent surface overlaps with an area where the number of overlapping layers of the uncoated portion is maintained at a standard number.

Description

[Technical field]

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

[0002] This application claims priority to Korean Patent Application No. 10-2021-0142196 filed on October 22, 2021 and Korean Patent Application No. 10-2022-0002970 filed on January 7, 2022, the entire contents of which are incorporated herein by reference in their entirety in the specification and drawings. [Background technology]

[0003] Batteries have high applicability for each product group, electrical properties such as high energy density, and can be repeatedly charged and discharged. They are widely used in electric vehicles (EVs) and hybrid electric vehicles (HEVs) that are driven by electric drive sources.

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

[0005] Currently, batteries such as lithium ion batteries, lithium polymer batteries, nickel cadmium batteries, nickel metal hydride batteries, and nickel zinc batteries are widely used. The operating voltage of such batteries is about 2.5V to 4.5V. Therefore, when a higher output voltage is required, a battery pack is constructed by connecting multiple batteries in series. In addition, a battery pack may be constructed by connecting multiple batteries in parallel according to the charge / discharge capacity required for the battery pack. Therefore, the number of batteries included in the battery pack and the electrical connection form may be variously set according to the required output voltage and / or charge / discharge capacity.

[0006] Meanwhile, known types of batteries include cylindrical, prismatic and pouch-type batteries. In the case of a cylindrical battery, a separator, which is an insulator, is interposed between a positive electrode and a negative electrode, and the separator is wound to form a jelly-roll-type electrode assembly, which is then inserted into a battery housing to form a battery. A strip-shaped electrode tab is connected to each uncoated portion of the positive electrode and the negative electrode, and the electrode tab electrically connects the electrode assembly to an electrode terminal exposed to the outside. For reference, the positive electrode terminal is a cap plate of a sealing body that seals an opening of the battery housing, and the negative electrode terminal is the battery housing. However, according to a conventional cylindrical battery having such a structure, current is concentrated in the strip-shaped electrode tab connected to the positive electrode uncoated portion and / or the negative electrode uncoated portion, which results in high resistance, high heat generation and poor current collection efficiency.

[0007] Resistance and heat generation are not a big issue for small cylindrical batteries with form factors such as 1865 and 2170. However, when the form factor of a cylindrical battery is increased to be used in an electric vehicle, a large amount of heat is generated around the electrode tabs during the fast charging process, which can cause the cylindrical battery to catch fire.

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

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

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

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

[0012] After the winding process, the uncoated portion 10a of the positive electrode 10 and the uncoated portion 11a of the negative electrode 11 are folded toward the core side. Then, the current collector plates 30 and 31 are welded and joined to the uncoated portions 10a and 11a, respectively.

[0013] No separate electrode tabs are attached to the positive electrode uncoated region 10a and the negative electrode uncoated region 11a, and the current collecting plates 30 and 31 are connected to external electrode terminals, and a current path is formed with a large cross-sectional area along the winding axis direction of the electrode assembly A (see arrow), 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.

[0014] In order to improve the welding characteristics between the uncoated portions 10a, 11a and the current collector plates 30, 31 in a tabless cylindrical battery, strong pressure must be applied to the welding points of the uncoated portions 10a, 11a to bend the uncoated portions 10a, 11a as flat as possible.

[0015] When the uncoated portions 10a, 11b are folded, the uncoated portion 32 adjacent to the core of the electrode assembly A is folded, completely or partially blocking the cavity 33 in the core of the electrode assembly A. In this case, a problem occurs in the electrolyte injection process. That is, the cavity 33 in the core of the electrode assembly A is used as a passage through which the electrolyte is injected. However, if the passage is blocked, it is difficult to inject the electrolyte. In addition, when an electrolyte injector is inserted into the cavity 33, it interferes with the uncoated portion 32 that is folded near the core, which may cause a problem of the uncoated portion 32 being torn.

[0016] In addition, the bent portions of the blank portions 10a, 11a where the current collector plates 30, 31 are welded must overlap in multiple places without leaving any open spaces (gaps). This ensures sufficient welding strength and prevents the laser from penetrating into the electrode assembly A and melting the separator or active material when using the latest technology such as laser welding.

[0017] In order for the uncoated portions 10a, 11a to overlap with the same number of layers, the uncoated portions 10a, 11a at the corresponding positions based on the positions of the respective winding turns must be folded toward the core and the inner winding turn must cover the top surface of the folded uncoated portion. In addition, when the distance between the uncoated portions of adjacent winding turns in the radial direction is d and the folding length of the uncoated portions 10a, 11a of each winding turn is e, the folding length e must be d×n (n is a natural number of 2 or more). Otherwise, there will be no area where the uncoated portions 10a, 11a overlap in the same number. In addition, in order to sufficiently form an area where the uncoated portions 10a, 11a overlap in the same number in the radial direction of the electrode assembly, the lengths of the uncoated portions 10a, 11a must be sufficiently long. However, since the radius of the electrode assembly included in a small cylindrical battery is small, there is no motivation to come up with the concept of designing the bent length of the uncoated portions 10a, 11a to be sufficiently long. Summary of the Invention [Problem to be solved by the invention]

[0018] The present invention has been made in light of the background of the prior art as described above, and has an object to provide an electrode assembly having a plain-portion folding structure that can prevent damage to a separator or an active material layer even when welding power is increased by sufficiently securing an area where the plain portions overlap by more than a minimum number of layers in the radial direction of the electrode assembly when the plain portions exposed at both ends of the electrode assembly are folded.

[0019] Another object of the present invention is to provide an electrode assembly having a plain portion bent structure that ensures sufficient overlapping area of ​​a standard number of plain portions that are approximately the same, making welding work easy and enabling uniform welding.

[0020] It is yet another object of the present invention to provide an electrode assembly in which an electrolyte injection passage is not blocked even when the uncoated portion is folded.

[0021] Another object of the present invention is to provide an electrode assembly in which an axial dimension of the electrode assembly is reduced to improve energy density and uncoated portions are densely laminated to reduce resistance.

[0022] It is yet another object of the present invention to provide a cylindrical battery including an electrode assembly of an improved structure, a battery pack including the same, and a vehicle including the battery pack.

[0023] The technical problem that the present invention is to solve is not limited to the above-mentioned problem, and other problems will be clearly understood by those skilled in the art from the following description of the invention. [Means for solving the problem]

[0024] In order to achieve the above object, an electrode assembly according to one aspect of the present invention is 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 around a single axis to define a core and an outer circumferential surface, and at least one of the first electrode and the second electrode includes a plain portion at a long side end thereof that is exposed to the outside of the separator along a longitudinal direction of the electrode assembly.

[0025] Preferably, the uncoated portion may itself be used as an electrode tab. At least a portion of the uncoated portion may be bent in a radial direction of the electrode assembly to form a bent surface, and the bent surface may include a first region extending in a radial direction where the number of overlapping layers of the uncoated portion is equal to or greater than a minimum number.

[0026] The number of overlapping layers of the uncoated portion may be defined as the number of uncoated portions intersecting an imaginary line drawn parallel to an axial direction of the electrode assembly at one point on the bent surface.

[0027] The folded surface may be formed by folding the non-coated portion based on a predetermined folding point.

[0028] The minimum number may be ten.

[0029] The folded surface may include a second region extending in a radial direction while maintaining a number of overlapping layers of the uncoated portion substantially equal to a reference number, and the second region may be included in the first region.

[0030] The reference number may be a maximum number of overlapping layers under design conditions of the non-coating portion, and may be equal to or greater than a minimum number, i.e., 10 or more.

[0031] The first region may include a first varying region in which the number of overlapping layers gradually increases in the radial direction, and a second varying region in which the number of overlapping layers gradually decreases in the radial direction.

[0032] The second region may be between the first and second variation regions.

[0033] For the sake of convenience, the total number of winding turns of the electrode including the uncoated portion is defined as n i (When i is 1, that is, n 1 is the factor for the first electrode, when i is 2, i.e., n 2 means that it is a factor related to the second electrode), then the winding turn index k (1 to n) at the kth winding turn position i (a natural number) is the total number of winding turns n i The relative radial position R for the winding turn index k is calculated by dividing the value by i,k It is defined as:

[0034] Here, k is a value obtained by counting the number of winding turns that appear in a cross section when the electrode assembly is cut along the axial direction. The cross section may be defined as a winding turn counting cross section. In the cross section, the winding turn counting cross section may be a right cross section or a left cross section based on the axial direction. For example, if a total of 50 winding turns appear in the right cross section or the left cross section, a winding turn index k from 1 to 50 may be assigned to each winding turn.

[0035] Meanwhile, the number of winding turns appearing in the right cross section or the left cross section may differ depending on the cutting position of the electrode assembly, and therefore the cutting position for obtaining the cross section of the electrode assembly is set so that the right cross section and the left cross section are bilaterally symmetrical with respect to the axial direction.

[0036] In the following description, the winding structure is a structure that appears on a winding turn counting cross section, and the number of winding turns or winding turn index is a value determined based on the winding structure that appears on the winding turn counting cross section.

[0037] Preferably, the number of overlapping layers of the plain part is 10 or more. i,k The ratio of the length of the radial section to the radius of the electrode assembly may be at least 25%.

[0038] Preferably, at least a portion of the uncoated portion is bent toward the core of the electrode assembly. The bent portion of the uncoated portion is referred to as a bent portion.

[0039] Preferably, the thickness of the first electrode and the second electrode is 80 μm to 250 μm. In the winding structure of the first electrode and the second electrode, the distance between the uncoated portions of the kth winding turn and the k+1th winding turn adjacent in the radial direction is 200 μm to 500 μm.

[0040] Preferably, in the winding structure of the first electrode, the relative radial position R 1,1 to the first relative radial position R 1,k* The height of the plain area in the section (A in Fig. 4) up to the k*+1th winding turn index is the relative radial position R1,k*+1 From the above R 1,k*+1 Relative radial position R located on the outer side of the 1,last The height of the plain area in the section up to may be lower.

[0041] The relative radial position R 1,last indicates the relative radial position of the uncoated portion of the first electrode that is bent toward the core with respect to the outermost winding turn index.

[0042] In one example, the relative radial position R 1,last can be 1.

[0043] As another example, the relative radial position R 1,last is R 1,n1-p It can be. R 1,n1-p indicates the relative radial position of the winding turn obtained by subtracting p turns from the outermost winding turn of the first electrode. The number of p turns is the number of turns that does not include the blank portion that is bent based on the outermost winding turn, and is a natural number of 1 or more. For example, the outermost winding turn of the first electrode, n turns, 1 th winding turn and n 1 -If there is no blank portion to be folded in the first winding turn, p is 2.

[0044] In addition, in the winding structure of the first electrode, the relative radial position R of the first winding turn 1,1 The first relative radial position R of the k*th winding turn preset from 1,k* In the section up to this point, the height of the plain portion may be lower than the folded surface formed by overlapping the folded plain portions.

[0045] In addition, in the winding structure of the first electrode, the relative radial position R of the first winding turn 1,1 The first relative radial position R of the k*th winding turn from 1,k* In the section up to, the uncoated portion does not need to be folded toward the core of the electrode assembly.

[0046] Preferably, in the winding structure of the second electrode, the relative radial position R of the first winding turn 2,1The first relative radial position R of the k*th winding turn preset from 2,k* The height of the plain area in the section (A' in Figure 4) up to the k*+1th winding turn is the relative radial position R 2,k*+1 From the above R 2,k*+1 Relative radial position R located on the outer side of the 2,last The height of the plain area in the section up to may be lower.

[0047] R 2,last indicates the relative radial position of the uncoated portion of the second electrode that is bent toward the core with respect to the outermost winding turn index.

[0048] In one example, the relative radial position R 2,last can be 1.

[0049] As another example, the relative radial position R 2,last is R 2,n2-p It can be. R 2,n2-p indicates the relative radial position of the winding turn obtained by subtracting p turns from the outermost winding turn of the second electrode. The number of p turns is the number of turns that does not include the blank portion that is bent based on the outermost winding turn, and is a natural number of 1 or more. For example, 2 th winding turn and n 2 -If there is no blank portion to be folded in the first winding turn, p is 2.

[0050] In addition, in the winding structure of the second electrode, the relative radial position R of the first winding turn 2,1 The first relative radial position R of the k*th winding turn preset from 2,k* In the section up to this point, the height of the plain portion may be lower than the folded surface formed by overlapping the folded plain portions.

[0051] In addition, in the winding structure of the second electrode, the relative radial position R of the first winding turn 2,1 The first relative radial position R of the k*th winding turn preset from 2,k* In the section up to, the uncoated portion does not need to be folded toward the core of the electrode assembly.

[0052] Preferably, the uncoated portion of the first electrode or the uncoated portion of the second electrode may be divided into a plurality of segments at a folded portion.

[0053] According to one example, each of the plurality of segments may be a rectangle, a trapezoid, a triangle, a parallelogram, a semicircle, or a semi-ellipse.

[0054] Preferably, each of the plurality of segments is a trapezoid, and a lower interior angle θ of the trapezoid may increase from the core side to the outer periphery side of the plurality of segments individually or for each group.

[0055] Preferably, in the winding structure of the first electrode, the relative radial position R of the first winding turn 1,1 The first relative radial position R of the k*th winding turn from 1,k* The height of the plain part in the section up to the k*+1th winding turn is the relative radial position R 1,k*+1 From the above R 1,k*+1 Relative radial position R located on the outer side of the 1,last The height of the uncoated portion of the section up to the core side must be lower than the height of the uncoated portion of the section up to the core side, and the uncoated portion does not have to be bent toward the core side.

[0056] The relative radial position R 1,last indicates the relative radial position of the uncoated portion of the first electrode that is bent toward the core with respect to the outermost winding turn index.

[0057] In one example, the relative radial position R 1,last can be 1.

[0058] As another example, the relative radial position R 1,last is R 1,n1-p It can be. R 1,n1-p indicates the relative radial position of the winding turn obtained by subtracting p turns from the outermost winding turn of the first electrode. The number of p turns is the number of turns that does not include the blank portion that is bent based on the outermost winding turn, and is a natural number of 1 or more. For example, the outermost winding turn of the first electrode, n turns, 1 th winding turn and n 1-If there is no blank portion to be folded in the first winding turn, p is 2.

[0059] Preferably, in the winding structure of the first electrode, the relative radial position R of the k*+1-th winding turn 1,k*+1 The folded length of the plain part in fd 1,k*+1 is the relative radial position R of the first winding turn 1,1 k*th relative radial position R 1,k* The radial length to the A ) may be the same as or shorter than

[0060] Preferably, in the winding structure of the first electrode, the cavity in the core of the electrode assembly is located at a relative radial position R of the k*+1th winding turn. 1,k*+1 ~R 1,last Therefore, the bent portion of the first electrode uncoated portion located in the section is not blocked.

[0061] Preferably, in the winding structure of the second electrode, the relative radial position R of the first winding turn 2,1 The first relative radial position R of the k*th winding turn from 2,k* The height of the plain part in the section up to the k*+1th winding turn is the relative radial position R 2,k*+1 From the above R 2,k*+1 Relative radial position R located on the outer side of the 2,last The height of the uncoated portion of the section up to the core side must be lower than the height of the uncoated portion of the section up to the core side, and the uncoated portion does not have to be bent toward the core side.

[0062] R 2,last indicates the relative radial position of the uncoated portion of the second electrode that is bent toward the core with respect to the outermost winding turn index.

[0063] In one example, the relative radial position R 2,last can be 1.

[0064] As another example, the relative radial position R 2,last is R 2,n2-p It can be. R 2,n2-pindicates the relative radial position of the winding turn obtained by subtracting p turns from the outermost winding turn of the second electrode. The number of p turns is the number of turns that does not include the blank portion that is bent based on the outermost winding turn, and is a natural number of 1 or more. For example, the outermost winding turn of the second electrode, n turns, is 2 th winding turn and n 2 -If there is no blank portion to be folded in the first winding turn, p is 2.

[0065] Preferably, in the winding structure of the second electrode, the relative radial position R of the k*+1-th winding turn 2,k*+1 The folded length of the plain part located at fd 2,k*+1 is the relative radial position R of the first winding turn 2,1 The first relative radial position R of the k*th winding turn from 2,k* The radial length to the A’ ) may be the same as or shorter than

[0066] Preferably, in the winding structure of the second electrode, the cavity in the core of the electrode assembly is located at a relative radial position R of the k*+1th winding turn. 2,k*+1 ~Relative radial position R 2,last The bent portion of the second electrode uncoated portion located in the section is not blocked.

[0067] Preferably, in the winding structure of the first electrode, the relative radial position R of the k*+1-th winding turn 1,k*+1 The second relative radial position R of the k@th winding turn preset from 1,k@ The uncoated portion in the section up to is divided into a plurality of segments, the height of which may increase stepwise or gradually toward the outer periphery.

[0068] Preferably, in the winding structure of the first electrode, a relative radial position R of a preset k@+1-th winding turn 1,k@+1 From R 1,k@+1 Relative radial position R located on the outer side of the 1,last The uncoated portion of the first electrode is divided into a plurality of segments, and the heights of the plurality of segments are set at the relative radial positions R 1,k@+1 Relative radial position R1,last may be approximately the same.

[0069] R 1,last indicates the relative radial position of the uncoated portion of the first electrode that is bent toward the core with respect to the outermost winding turn index.

[0070] In one example, the relative radial position R 1,last can be 1.

[0071] As another example, the relative radial position R 1,last is R 1,n1-p It can be. R 1,n1-p indicates the relative radial position of the winding turn obtained by subtracting p turns from the outermost winding turn of the first electrode. The number of p turns is the number of turns that does not include the blank portion that is bent based on the outermost winding turn, and is a natural number of 1 or more. For example, the outermost winding turn of the first electrode, n turns, 1 th winding turn and n 1 -If there is no blank portion to be folded in the first winding turn, p is 2.

[0072] Preferably, in the winding structure of the second electrode, the relative radial position R of the k*+1-th winding turn 2,k*+1 The second relative radial position R of the k@th winding turn preset from 2,k@ The uncoated portion in the section up to is divided into a plurality of segments, the height of which may increase stepwise or gradually toward the outer periphery.

[0073] Preferably, in the winding structure of the second electrode, the second relative radial position R of the k@+1-th winding turn 2,k@+1 From R 2,k@ Relative radial position R located on the outer side of the 2,last The uncoated portion of the second electrode is divided into a plurality of segments, and the height of each segment is the relative radial position R of the k@+1th winding turn. 2,k@+1 Relative radial position R 2,last may be approximately the same.

[0074] R 2,lastindicates the relative radial position of the uncoated portion of the second electrode that is bent toward the core with respect to the outermost winding turn index.

[0075] In one example, the relative radial position R 2,last can be 1.

[0076] As another example, the relative radial position R 2,last is R 2,n2-p It can be. R 2,n2-p indicates the relative radial position of the winding turn obtained by subtracting p turns from the outermost winding turn of the second electrode. The number of p turns is the number of turns that does not include the blank portion that is bent based on the outermost winding turn, and is a natural number of 1 or more. For example, the outermost winding turn of the second electrode, n turns, is 2 th winding turn and n 2 -If there is no blank portion to be folded in the first winding turn, p is 2.

[0077] Preferably, in the winding structure of the first electrode, the uncoated portion bent toward the core side is divided into a plurality of segments, and at least one of the height in the winding axial direction and the width in the winding direction of the plurality of segments may increase stepwise from the core side to the outer periphery, either individually or for each group.

[0078] Preferably, in the winding structure of the second electrode, the uncoated portion bent toward the core side is divided into a plurality of segments, and at least one of the height in the winding axial direction and the width in the winding direction of the plurality of segments may increase stepwise from the core side to the outer periphery, either individually or for each group.

[0079] Desirably, when the folded portion of the plain portion is divided into a plurality of segments, each of the plurality of segments can satisfy at least one of the following conditions: a width D1 of 1 mm to 11 mm in the winding direction, a height D2 of 2 mm to 10 mm in the winding axial direction, and a spacing pitch D3 of 0.05 mm to 1 mm in the winding direction.

[0080] Preferably, a predetermined gap G may be provided between a lower end D4 of the cut groove of the divided piece and the active material layer.

[0081] Preferably, an insulating coating layer is formed in a boundary region between the non-coating portion and the active material layer, and a predetermined gap G may be provided between a lower end D4 of the cut groove of the divided piece and the insulating coating layer.

[0082] The gap G may be between 0.2 mm and 4 mm.

[0083] Preferably, when the folded portion of the plain portion is divided into a plurality of segments, the plurality of segments form a plurality of segment groups from the core side toward the outer periphery side, and the segments belonging to the same segment group may be identical to each other in at least one element of the width in the winding direction, the height in the winding axial direction, and the separation pitch in the winding direction.

[0084] Preferably, the one or more elements that are the same in the segments belonging to the same segment group may increase gradually or stepwise from the core side toward the outer periphery side.

[0085] Preferably, the segments belonging to the same segment group may have at least one of the width in the winding direction, the height in the winding axial direction, and the separation pitch in the winding direction gradually or stepwise increasing from the core side to the outer periphery side.

[0086] In one example, at least some of the multiple segment groups may be disposed on the same winding turn of the electrode assembly.

[0087] The segments belonging to the same segment group may constitute a part or all of the same winding turn and a part of the winding turn adjacent thereto.

[0088] The segments belonging to the same segment group may constitute the entirety of the same winding turn, part or all of the winding turn adjacent thereto on the core side, and part or all of the winding turn adjacent thereto on the outer circumferential side.

[0089] The above objectives are achieved by a cylindrical battery including the above-mentioned electrode assembly. the cylindrical battery includes 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 around one axis to define a core and an outer circumferential surface, the electrode assembly including an uncoated portion exposed to the outside of the separator along a longitudinal direction of the electrode assembly at a long side end of at least one of the first electrode and the second electrode, at least a portion of the uncoated portion being folded in a radial direction of the electrode assembly to form a folded surface, the folded surface including a region (second region) in which a number of overlapping layers of the uncoated portion is maintained constant at a reference number along the radial direction; a battery housing in which the electrode assembly is housed and electrically connected to one of the first electrode and the second electrode and has a first polarity; a sealing body that seals an open end of the battery housing; a terminal that is electrically connected to the other of the first electrode and the second electrode, the surface of which is exposed to the outside and has a second polarity; and a current collector that is welded to overlap at least a portion of the region and is electrically connected to one of the battery housing or the terminal.

[0090] Preferably, the total number of winding turns of the electrode including the uncoated portion is n i (When i is 1, it means that it is a factor related to the first electrode, and when i is 2, it means that it is a factor related to the second electrode), then the winding turn index k (1 to n) at the kth winding turn position is i (a natural number) is the total number of winding turns n i The relative radial position R for the winding turn index k is calculated by dividing the value by i,k If we define it as R, which satisfies the condition that the number of overlapping layers of the plain part is 10 or more, i,k The ratio of the length of the radial section to the radius of the electrode assembly may be at least 25%.

[0091] The second region and the welding region of the current collector plate may overlap by 50% or more in a radial direction of the electrode assembly.

[0092] The overlap ratio of the welding area may be determined as a ratio of an area of ​​the welding area that belongs to the second area to an entire area of ​​the welding area. The welding area may be an area where a weld bead is substantially formed.

[0093] The above object is also achieved by a battery pack including the above-mentioned cylindrical battery, and a vehicle including the same. Effect of the Invention

[0094] According to one aspect of the present invention, when uncoated portions exposed at both ends of an electrode assembly are bent, a sufficient area is ensured in the radial direction of the electrode assembly where the uncoated portions overlap by at least a minimum number of layers, thereby preventing damage to a separator or an active material layer even when welding power is increased. The minimum number of layers may be 10 layers.

[0095] According to another aspect of the present invention, when bending the uncoated portion, an area in which the number of overlapping layers of the uncoated portion is kept constant at a reference number is sufficiently secured in the radial direction of the electrode assembly, thereby enabling easy and precise welding. The reference number may be 10 or more.

[0096] In addition, according to one aspect of the present invention, by improving the structure of the uncoated portion adjacent to the core of the electrode assembly, it is possible to prevent the cavity in the core of the electrode assembly from being blocked when the uncoated portion is bent, thereby facilitating the electrolyte injection process and the welding process of the battery housing and the current collector plate.

[0097] In addition, according to one aspect of the present invention, an electrode assembly having improved energy density and reduced resistance can be provided by directly welding a bent surface of an uncoated portion to a current collecting plate instead of using a strip-shaped electrode tab.

[0098] In addition, according to one aspect of the present invention, it is possible to provide a cylindrical battery having a structure with low internal resistance and improved welding strength between a current collector plate and an uncoated portion, and a battery pack and a vehicle including the same.

[0099] The present invention has various other effects, which will be described later with reference to the embodiments, but the description of the effects that can be easily inferred by ordinary skilled artisans will be omitted.

[0100] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention, serve to further understand the technical ideas of the present invention. Therefore, the present invention should not be interpreted as being limited only to the matters described in the drawings. [Brief description of the drawings]

[0101] [Figure 1] FIG. 1 is a plan view showing the structure of an electrode used in the manufacture of a conventional tabless cylindrical battery. [Diagram 2] FIG. 1 is a diagram showing an electrode winding process for a conventional tabless cylindrical battery. [Diagram 3] 1 is a diagram showing a process of welding a current collector plate to a bent surface of a non-coating portion in a conventional tabless cylindrical battery. [Figure 4] FIG. 2 is a plan view showing a structure of an electrode according to an embodiment of the present invention. [Diagram 5] FIG. 2 is a diagram illustrating the definition of the width, height, and spacing pitch of segments according to an embodiment of the present invention. [Figure 6] 2 is a view showing a wound turn structure of a first electrode in an upper portion of an electrode assembly according to an embodiment of the present invention. FIG. [Figure 7] 4 is a view showing a wound turn structure of a second electrode at a lower portion of an electrode assembly according to an embodiment of the present invention. FIG. [Figure 8] This is a partial cross-sectional view showing an electrode assembly with a radius of 22 mm contained in a cylindrical battery of form factor 4680, in which the uncoated portion of the first electrode is bent from the outer periphery side to the core side, and the radial length of the relative radial position section where 10 or more sheets overlap is 25% or more based on the radius of the electrode assembly. [Figure 9] 1 is a cross-sectional view of a cylindrical battery according to an embodiment of the present invention taken along a Y-axis direction. [Figure 10]FIG. 4 is a cross-sectional view of a cylindrical battery according to another embodiment of the present invention taken along the Y-axis direction. [Figure 11] FIG. 2 illustrates a battery pack including a cylindrical battery according to an embodiment of the present invention. [Figure 12] FIG. 1 illustrates a vehicle including a battery pack according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0102] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings. Prior to this, the terms and words used in the present specification and claims are not to be construed as being limited to their ordinary and dictionary meanings, but are to be construed as having meanings and concepts corresponding to the technical ideas of the present invention, in accordance with the principle that the inventors themselves can appropriately define the concepts of terms in order to best describe the invention.

[0103] Therefore, it should be understood that the embodiment described in this specification and the configurations shown in the drawings are merely the most preferred embodiment of the present invention and do not represent the entire technical idea of ​​the present invention, and therefore there may be various equivalents and modifications that can be substituted therefor at the time of this application.

[0104] In addition, in order to facilitate understanding of the invention, the accompanying drawings may not be drawn to scale, and the dimensions of some components may be exaggerated. Also, the same reference numerals may be used to refer to the same components in different embodiments.

[0105] First, an electrode assembly according to an embodiment of the present invention will be described. The electrode assembly is a jelly-roll type electrode assembly in which a sheet-like first electrode and a sheet-like second electrode are wound around one axis with a separator interposed therebetween to define a core and an outer circumferential surface.

[0106] For ease of explanation, in this specification, the direction along the length of the winding shaft of the electrode assembly wound into a jelly roll is referred to as the axial direction (Y axis). The direction surrounding the winding shaft is referred to as the circumferential direction or outer circumferential direction (X axis direction). The direction approaching the winding shaft or away from the winding shaft is referred to as the radial direction or radial direction (Z axis direction). Of these, the direction approaching the winding shaft is referred to as the centripetal direction, and the direction away from the winding shaft is referred to as the centrifugal direction. Thus, it can be understood that the width direction of the electrode assembly before winding corresponds to the winding axial direction and the Y axis, and the length direction of the electrode assembly before winding corresponds to the outer circumferential direction and the X axis.

[0107] Preferably, at least one of the first electrode and the second electrode includes a plain area where no active material is coated on a long side end in the winding direction. At least a part of the plain area is used as an electrode tab by itself. According to an embodiment, the first electrode includes a plain area at an upper end in the drawing, and the second electrode includes a plain area at a lower end in the drawing.

[0108] FIG. 4 is a plan view showing the structure of an electrode 40 according to an embodiment of the present invention.

[0109] Referring to FIG. 4, the electrode 40 of the first embodiment includes a current collector 41 made of a metal foil, and an active material layer 42. The metal foil may be aluminum or copper, and is appropriately selected according to the polarity of the electrode 40. The active material layer 42 is formed on at least one surface of the current collector 41, and includes a non-coated portion 43 at a long side end in the winding direction X. The non-coated portion 43 is an area where the active material is not coated. For reference, the winding direction X of the electrode 40 that is unrolled before winding corresponds to the outer circumferential direction (circumferential direction) surrounding the central axis of the cylindrical electrode assembly after winding. An insulating coating layer 44 may be formed at the boundary between the active material layer 42 and the non-coated portion 43. The insulating coating layer 44 is formed so that at least a portion of the insulating coating layer 44 overlaps with the boundary between the active material layer 42 and the non-coated portion 43. The insulating coating layer 44 includes a polymer resin, and is preferably made of SiO 2 , Al 2 O 3 The resin may contain inorganic fillers such as

[0110] Desirably, the folded portion of the uncoated portion 43 of the electrode 40 may include a plurality of divided segments 61. The plurality of divided segments 61 may have a height that increases stepwise from the core side toward the outer periphery in at least a portion of the winding direction. The section where the height increases stepwise may be present in other regions except for the uncoated region adjacent to the core side of the electrode assembly (core-side uncoated portion A). Desirably, the core-side uncoated portion A has a height that is relatively lower than other portions. The number of winding turns included in the core-side uncoated portion A may be preset.

[0111] The section 61 may be laser notched. The section 61 may be formed by known metal foil cutting processes such as ultrasonic cutting or stamping.

[0112] In order to prevent damage to the active material layer 42 and / or the insulating coating layer 44 during the folding process of the plain portion 43, it is preferable to provide a certain gap between the lower end of the cut groove between the divided pieces 61 (D4 in FIG. 5, the portion shown by the dashed line in FIG. 6 and FIG. 7) and the active material layer 42 and / or the insulating coating layer 44. This is because stress is concentrated near the lower end of the cut groove when the plain portion 43 is folded. The gap is preferably 0.2 mm to 4 mm. By adjusting the gap to the above numerical range, it is possible to prevent damage to the active material layer 42 and / or the insulating coating layer 44 near the lower end of the cut groove due to stress generated during the folding process of the plain portion 43. The cut groove may be replaced by a cut line. The cut line may be formed by cutting the plain portion 43 with a cutter, and the plain portion 43 is not substantially removed at the portion where the cut line is formed. In the present invention, the cut line is also regarded as an equivalent of the cut groove.

[0113] The plurality of segment pieces 61 may be arranged into a plurality of segment piece groups from the core side toward the outer periphery side. The width, height, and spacing pitch of the segment pieces belonging to the same segment piece group may be substantially the same.

[0114] FIG. 5 is a diagram illustrating the definition of the width, height, and spacing pitch of the segment pieces 61 according to an embodiment of the present invention.

[0115] 5, the width D1, height D2 and spacing D3 of the divided pieces 61 are designed to prevent the uncoated portion 43 from tearing during bending and to improve the weld strength by sufficiently increasing the number of overlapping layers of the uncoated portion 43 and to prevent abnormal deformation of the uncoated portion 43. Abnormal deformation means that the uncoated portion below the bending point D4 cannot maintain a straight state and collapses, becoming irregularly deformed.

[0116] Desirably, the width D1 of the divided piece 61 can be adjusted in the range of 1 mm to 11 mm. If D1 is less than 1 mm, when the divided piece 61 is bent toward the core, an area that does not overlap to an extent that sufficient welding strength can be ensured or an empty space (gap) will be generated. On the other hand, if D1 exceeds 11 mm, there is a risk that the uncoated portion 43 near the bending point D4 will break due to stress when the divided piece 61 is bent.

[0117] The height of the divided piece 61 can be adjusted within a range of 2 mm to 10 mm. If D2 is less than 2 mm, when the divided piece 61 is bent toward the core, a region that does not overlap to an extent that sufficient welding strength can be ensured or an empty space (gap) will be generated. On the other hand, if D2 exceeds 10 mm, it is difficult to manufacture an electrode while maintaining uniform flatness of the uncoated portion in the winding direction X. In other words, the uncoated portion becomes higher and swells.

[0118] The separation pitch D3 of the divided pieces 61 can be adjusted in the range of 0.05 mm to 1 mm. If D3 is less than 0.05 mm, the uncoated portion 43 near the bending point D4 may be broken due to stress when the divided pieces 61 are bent, and the impregnation of the electrolyte may decrease. On the other hand, if D3 exceeds 1 mm, the impregnation of the electrolyte does not increase any more, but when the divided pieces 61 are bent, there is a risk that an area where the divided pieces 61 do not overlap to an extent that sufficient welding strength can be ensured or an empty space (gap) may occur.

[0119] Referring further to FIG. 4, the width (length in the winding direction) d of the core-side plain portion A A is designed so that the cavity of the core of the electrode assembly is not blocked when the divided piece 61 is bent towards the core.

[0120] In one example, the width d of the core-side plain portion A A may increase in proportion to the bending length of the portion segment 61 of group 1. The bending length corresponds to the height D2 of the portion segment 61 based on the bending point (D4 in FIG. 5).

[0121] In a specific example, when the electrode 40 is used to manufacture an electrode assembly for a cylindrical battery of form factor 4680, the width d of the core-side blank portion A is A can be set to 180 mm to 350 mm depending on the diameter of the core of the electrode assembly.

[0122] In one example, the width of each segment group can be designed to accommodate the same winding turn of the electrode assembly.

[0123] The same winding turn may belong to one segment group.

[0124] Less than one winding turn may belong to one segment group.

[0125] One or more winding turns may belong to one segment group, where the one or more winding turns may include partial winding turns, which are winding turns represented by a natural number less than 1, such as 5 / 10 turns, 4 / 10 turns, 3 / 10 turns, etc.

[0126] In a modified example, the width and / or height and / or spacing pitch of the segments 61 belonging to the same segment group may increase or decrease gradually and / or stepwise and / or irregularly within the group.

[0127] Groups 1 to 7 are merely examples of segment groups. The number of groups and the number of segment pieces 61 included in each group may be adjusted so that the segment pieces 61 are overlapped in multiple layers to maximize stress dispersion during the bending process of the plain portion 43 and ensure sufficient welding strength.

[0128] In a modified embodiment, a portion of the group of segments may be removed. In this case, the height of the uncoated portion from which the segments have been removed may be the same as the height of the core-side uncoated portion A.

[0129] The partial group may include a group that constitutes the outermost winding turn.

[0130] After the predetermined section, the height of the segments may be maintained substantially uniform up to the outer periphery of the electrode assembly. In the illustrated example, the height of the segments located on the outer periphery side of group 7 may be substantially uniform.

[0131] In a specific example, the width d of the core-side plain portion A A may be 180-350mm. The width of group 1 may be 35-55% of the width of core-side plain portion A. The width of group 2 may be 120-150% of the width of group 1. The width of group 3 may be 110-135% of the width of group 2. The width of group 4 may be 75-90% of the width of group 3. The width of group 5 may be 120-150% of the width of group 4. The width of group 6 may be 100-120% of the width of group 5. The width of group 7 may be 90-120% of the width of group 6.

[0132] The reason why the widths of groups 1 to 7 do not show a constant increase or decrease pattern is that although the widths of the sub-segments gradually increase from group 1 to group 7, the number of sub-segments included in a group is limited to an integer. Therefore, the number of sub-segments may decrease in a particular sub-segment group. Therefore, the widths of the groups may show an irregular change from the core side to the outer periphery side, as shown in the above example.

[0133] That is, when the winding direction widths of three adjacent segment groups that are consecutively adjacent in the radial direction of the electrode assembly are W1, W2, and W3, respectively, the combination of segment groups may include one in which W3 / W2 is smaller than W2 / W1.

[0134] In the specific example described above, this applies to groups 4 to 6. The width ratio of group 5 to group 4 is 120 to 150%, and the width ratio of group 6 to group 5 is 100 to 120%, which is smaller than 120 to 150%.

[0135] Preferably, the lower interior angle θ of the trapezoid of the plurality of segment pieces 61 may increase from the core side toward the outer periphery. As the radius of the electrode assembly increases, the radius of curvature increases. If the lower interior angle θ of the segment pieces 61 increases with the increase in the radius of the electrode assembly, stresses occurring in the radial and circumferential directions when the segment pieces 61 are bent can be alleviated. In addition, if the lower interior angle θ increases, the overlapping area and the number of overlapping layers with the inner segment pieces 61 when the segment pieces 61 are bent also increase, so that uniform welding strength can be secured in the radial and circumferential directions, and the bent surface can be formed flat. In addition, the gap between adjacent segment pieces in the bent state can be reduced.

[0136] In one example, when the electrode 40 is used to manufacture an electrode assembly for a cylindrical battery of form factor 4680, the interior angle of the segment 61 may increase stepwise in the interval of 60° to 85° as the radius of the electrode assembly 40 increases from 4 mm to 22 mm.

[0137] In the present invention, the shape of the segment 61 can be changed to a triangle, a semicircle, a semi-ellipse, a parallelogram, or the like.

[0138] In addition, the shape of the segment 61 may be changed to be different depending on the position. For example, a round shape (e.g., semicircle, semiellipse, etc.) that is advantageous for dispersing stress may be applied to a section where stress is concentrated, and a polygonal shape (e.g., square, trapezoid, parallelogram, etc.) with the largest possible area may be applied to a section where stress is relatively low.

[0139] The division structure of the uncoated portion can also be applied to the core-side uncoated portion A. However, if a division structure is applied to the core-side uncoated portion A, a phenomenon called reverse forming may occur in which the end of the core-side uncoated portion A bends toward the outer periphery when the division piece is bent depending on the curvature radius of the core. Therefore, it is preferable not to apply a division structure to the core-side uncoated portion A, or, even if a division structure is applied, to adjust the width and / or height and / or spacing pitch of the division pieces 61 to a level that does not cause reverse forming, taking into account the curvature radius of the core.

[0140] The electrode structure of the above-mentioned embodiment (variant) may be applied to the first electrode and / or the second electrode having different polarities included in the jelly roll type electrode assembly. In addition, when the electrode structure of the embodiment (variant) is applied to one of the first electrode and the second electrode, a conventional electrode structure may be applied to the other. In addition, the electrode structures applied to the first electrode and the second electrode may not be the same, but may be different.

[0141] As an example, when the first electrode and the second electrode are positive and negative electrodes, respectively, any one of the embodiments (variations) may be applied to the first electrode, and a conventional electrode structure (see FIG. 1) may be applied to the second electrode.

[0142] As another example, when the first electrode and the second electrode are a positive electrode and a negative electrode, respectively, any one of the embodiments (variants) may be selectively applied to the first electrode, and any one of the embodiments (variants) may be selectively applied to the second electrode.

[0143] In the present invention, the positive electrode active material coated on the positive electrode and the negative electrode active material coated on the negative electrode may be any active material known in the art without any limitations.

[0144] As an example, the positive electrode active material can be represented by the general chemical formula A[A x M y ]O 2+z(A contains at least one element of Li, Na, and K; M contains at least one element selected from Ni, Co, Mn, Ca, Mg, Al, Ti, Si, Fe, Mo, V, Zr, Zn, Cu, Al, Mo, Sc, Zr, Ru, and Cr; x≧0, 1≦x + y≦2, -0.1≦z≦2; the stoichiometric coefficients x, y, and z are selected such that the compound maintains electrical neutrality) may contain an alkali metal compound represented thereby.

[0145] As another example, the positive electrode active material is an alkali metal compound xLiM disclosed in U.S. Patent No. 6,677,082, U.S. Patent No. 6,680,143, etc. 1 O 2 -(1 - x)Li 2 M 2 O 3 (M 1 contains at least one element having an average oxidation state of 3; M 2 contains at least one element having an average oxidation state of 4; 0≦x≦1) may be.

[0146] As yet another example, the positive electrode active material is generally represented by the chemical formula Li a M 1 x Fe 1-x M 2 y P 1-y M 3 z O 4-z (M 1 contains at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg, and Al; M 2 contains at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg, Al, As, Sb, Si, Ge, V, and S; M 3 contains a halogen group element selectively containing F; 0 < a≦2, 0≦x≦1, 0≦y < 1, 0≦z < 1; the stoichiometric coefficients a, x, y, and z are selected such that the compound maintains electrical neutrality), or Li 3 M 2 (PO 4 ) 3[M includes at least one element selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Al, Mg, and Al].

[0147] Desirably, the positive electrode active material may include primary particles and / or secondary particles formed by aggregation of the primary particles.

[0148] For example, the negative electrode active material may be a carbon material, lithium metal or a lithium metal compound, silicon or a silicon compound, tin or a tin compound, etc. 2 , SnO 2 Metal oxides such as the following can also be used as the negative electrode active material. As the carbon material, either low crystalline carbon or high crystalline carbon can be used.

[0149] The separator may be a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, an ethylene / methacrylate copolymer, etc., used alone or in combination. As another example, the separator may be a conventional porous nonwoven fabric, for example, a nonwoven fabric made of a high melting point glass fiber, a polyethylene terephthalate fiber, etc.

[0150] At least one surface of the separation membrane may include a coating layer of inorganic particles. Alternatively, the separation membrane itself may be made of a coating layer of inorganic particles. The particles constituting the coating layer may have a structure in which they are bound with a binder such that there is an interstitial volume between adjacent particles.

[0151] The inorganic particles may be made of an inorganic material having a dielectric constant of 5 or more. As a non-limiting example, the inorganic particles may be 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 , hafnia (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 composition may include at least one material selected from the group consisting of:

[0152] The electrode assembly according to one embodiment is a jelly-roll type electrode assembly 80 in which the electrode 40 according to the embodiment is applied to a first electrode (positive electrode) and a second electrode (negative electrode).

[0153] FIG. 6 is a diagram showing the wound turn structure of the first electrode (positive electrode) in the upper part of the electrode assembly 80, and FIG. 7 is a diagram showing the wound turn structure of the second electrode (negative electrode) in the lower part of the electrode assembly 80.

[0154] The electrode assembly 80 can be manufactured by the winding method described with reference to FIG. 2. For ease of explanation, the protruding structure of the uncoated portions 43a, 43a' extending outward from the separator is shown in detail, and a detailed illustration of the separator winding structure is omitted. The uncoated portion 43a protruding to the upper side of the electrode assembly 80 is extended from the first electrode 40. The uncoated portion 43a' protruding to the lower side of the electrode assembly 80 is extended from the second electrode 40'. The end positions of the separator are indicated by dashed lines.

[0155] The pattern in which the height of uncoated portions 43a, 43a' varies is illustrated diagrammatically. That is, the height of uncoated portions 43a, 43a' may vary irregularly depending on the cutting position of the cross section. As an example, if a side edge of trapezoidal segment 61 is cut, the height of the uncoated portions in the cross section will be lower than the height of segment 61. Therefore, it should be understood that the height of uncoated portions 43a, 43a' illustrated in the drawing showing the cross section of electrode assembly 80 corresponds to the average height (D2 in FIG. 5) of the uncoated portions included in each winding turn.

[0156] Hereinafter, the structural characteristics of the uncoated portion 43a of the first electrode 40 will be described in detail with reference to the drawings. Preferably, the uncoated portion 43a' of the second electrode 40' may have substantially the same characteristics as the uncoated portion 43a of the first electrode 40.

[0157] 6 and 7, the uncoated portions 43a, 43a' of the first electrode 40 and the second electrode 40' may themselves be used as electrode tabs.

[0158] In the winding structure of the first electrode 40, the total number of winding turns of the first electrode 40 is n 1 Let the winding turn number index k(1 to n 1 (a natural number) is the total number of winding turns n 1 The relative radial position R of the kth winding turn is calculated by dividing the value by 1,k When the number of overlapping layers of the folded part of the plain part is defined as 10 or more, the relative radius position R 1,k The length of the section (referred to as the first region) in the radial direction is 25% or more based on the radius of the electrode assembly 80 .

[0159] For reference, the relative radial position of the first winding turn is 1 / n 1 The relative radial position of the kth winding turn is k / n 1 The last n 1 The relative radial position of the th winding turn is 1. That is, the relative radial position is 1 / n from the core side of the electrode assembly 80 toward the outer periphery. 1 to 1.

[0160] In the winding structure of the second electrode 40′, the total number of winding turns of the second electrode 40′ is n 2 The winding turn index k(1 to n 2 (a natural number) is the total number of winding turns n 2 The relative radial position R of the kth winding turn is calculated by dividing the value by 2,k When the number of overlapping layers of the folded part of the plain part is defined as 10 or more, the relative radius position R 2,k The radial length of the section (referred to as a first region) is 25% or more based on the radius of the electrode assembly 80 .

[0161] For reference, the relative radial position of the first winding turn is 1 / n 2 The relative radial position of the kth winding turn is k / n 2 The last n 2 The relative radial position of the th winding turn is 1. That is, the relative radial position is 1 / n from the core side of the electrode assembly 80 toward the outer periphery. 2 to 1.

[0162] Preferably, the winding turn index k of the first electrode 40 and the winding turn index k of the second electrode 40' should be understood as variables which can be assigned different values.

[0163] When welding the current collector plate (see 30 and 31 in FIG. 3) to the bent surface of the uncoated portions 43a and 43a', it is preferable to increase the output of the laser in order to secure sufficient welding strength. If the output of the laser is increased, the laser may penetrate the overlapping region of the uncoated portions 43a and 43a' into the inside of the electrode assembly 80, damaging the separator, active material, etc. Therefore, in order to prevent the laser from penetrating, it is preferable to increase the number of overlapping layers of the uncoated portions 43a and 43a' to more than the minimum number. In order to increase the number of overlapping layers of the uncoated portions 43a and 43a', the height of the divided pieces 61 must be increased. However, if the height of the divided pieces 61 is increased, there is a risk that swells will occur in the uncoated portions 43a and 43a' during the manufacturing process of the electrode 40. Therefore, it is preferable to adjust the height of the divided pieces 61 to an appropriate level.

[0164] As described above, if the ratio of the radial length of the relative radial position section where the number of overlapping layers of the folded parts of the uncoated portion is 10 or more is designed to be 25% or more based on the radius of the electrode assembly, and the current collecting plates are laser welded so that the area where 10 or more folded parts of the uncoated portion overlap with at least a portion of the welding area, the overlapping areas of the uncoated portion can adequately mask the laser even if the laser output is increased, thereby preventing damage to the separator, active material, etc. by the laser.

[0165] Preferably, the laser output is adjusted to 260 W or more, but the present invention is not limited thereto. When the laser output is increased to 260 W or more, the welding strength can be sufficiently increased. In one example, the welding strength is increased to 2 kgf / cm 2 It can be increased to more than 100%.

[0166] On the other hand, in the winding structure of the first electrode 40, the number of overlapping layers of the folded portion of the non-coated portion is 10 or more, and the relative radial position R 1,k The length of the section (referred to as the second region) in the radial direction is 25% or more based on the radius of the electrode assembly 80.

[0167] In the wound structure of the first electrode 40, the certain number may be the maximum number of overlapping layers under the design conditions of the uncoated portion of the first electrode 40.

[0168] In the winding structure of the second electrode 40′, the number of overlapping layers of the folded portion of the non-coated portion is 10 or more, and the relative radial position R 2,k The length of the section (referred to as the second region) in the radial direction is 25% or more based on the radius of the electrode assembly 80.

[0169] In the wound structure of the second electrode 40', the certain number may be the maximum number of overlapping layers under the design conditions of the uncoated portion of the second electrode 40'.

[0170] When welding a current collecting plate to the bent surface of the non-coated portion, it is preferable that all overlapping layers of the bent surface corresponding to the welding point are welded. Therefore, if the welding strength is increased according to the number of overlapping layers, all overlapping layers can be welded together. However, if there are areas where the number of overlapping layers differs in the area where welding is performed, some areas will be over-welded and other areas will be under-welded. Therefore, in the embodiment, it is intended to secure an additional area in the radial direction of the electrode assembly where the number of overlapping layers is constant while being equal to or greater than the minimum number (10). This is achieved by a pattern in which the height of the non-coated portion is gradually increased from the core side to the outer shell side and then maintained constant. A specific embodiment of this will be described later.

[0171] Desirably, the first electrode 40 includes a current collector 41 and an active material coating layer 42 formed on at least one surface thereof, the current collector 41 having a thickness of 10 μm to 25 μm, and the interval between uncoated portions of adjacent wound turns in the radial direction of the electrode assembly 80 may be 200 μm to 500 μm. The current collector 41 of the first electrode 40 may be made of aluminum.

[0172] The second electrode 40' includes a current collector and an active material coating layer formed on at least one surface of the current collector, the current collector having a thickness of 5 μm to 20 μm, and the spacing between uncoated portions of adjacent wound turns in the radial direction of the electrode assembly 80 may be 200 μm to 500 μm. The current collector of the second electrode 40' may be made of copper.

[0173] Preferably, in the winding structure of the first electrode 40, the relative radial position R of the first electrode 40 1,1 to the first relative radial position R 1,k* Section r up to A The height of the plain part is the relative radial position R of the winding turn number k*+1. 1,k*+1 The height of the plain area in the section from the relative radius position R to the relative radius position 1 may be lower than that of the plain area in the section from the relative radius position R 1,1 to the first relative radial position R 1,k* The height of the uncoated area in the section up to corresponds to the height of the uncoated area of ​​the core-side uncoated area A (see FIG. 4).

[0174] In the embodiment, the relative radial position 1 is R 1,last It can be replaced by R 1,last indicates the relative radial position of the uncoated portion of the first electrode 40 that is bent toward the core side with respect to the outermost winding turn index. 1,last is R 1,n1-p It can be. R 1,n1-p indicates the relative radial position of the winding turn obtained by subtracting p turns from the outermost winding turn of the first electrode. The number of p turns is the number of turns that does not include the blank portion that is bent based on the outermost winding turn. For example, the outermost winding turn of the first electrode, n 1 th winding turn and n 1 -If there is no blank portion to be folded in the first winding turn, p is 2.

[0175] Preferably, in the winding structure of the first electrode 40, the relative radial position R 1,1 to the first relative radial position R 1,k* The height of the plain portion in section A up to the folded portion can be lower than the folded surface B formed by overlapping the folded plain portions.

[0176] Preferably, in the winding structure of the first electrode 40, the relative radial position R 1,1 to the first relative radial position R 1,k* In the section up to , the uncoated portion does not need to be folded toward the core of the electrode assembly 80.

[0177] Similar to the first electrode 40, the second electrode 40′ has a winding structure with a relative radial position R 2,1 to the first relative radial position R 2,k* The height of the plain area in the section up to the k*+1 winding turn is the relative radial position R 2,k*+1 may be lower than the height of the uncoated area in the section from to relative radial position 1.

[0178] In the embodiment, the relative radial position 1 is R 2,last It can be replaced by R 2,lastindicates the relative radial position of the uncoated portion of the second electrode that is bent toward the core with respect to the outermost winding turn index. 2,last is R 2,n2-p It can be. R 2,n2-p indicates the relative radial position of the winding turn obtained by subtracting p turns from the outermost winding turn of the second electrode. The number of p turns is the number of turns that does not include the blank portion that is bent based on the outermost winding turn. For example, the outermost winding turn of the second electrode, n 2 th winding turn and n 2 -If there is no blank portion to be folded in the first winding turn, p is 2.

[0179] Preferably, the relative radial position R 2,1 to the first relative radial position R 2,k* In the section up to this point, the height of the plain portion may be lower than the folded surface formed by overlapping the folded plain portion.

[0180] Preferably, the relative radial position R 2,1 to the first relative radial position R 2,k* The uncoated portion in the section up to (A' in FIG. 4) does not need to be folded toward the core of the electrode assembly.

[0181] During the manufacturing process of the secondary battery, including the process of inserting the electrode assembly 80 into the battery housing, unintentional deformation or buckling may occur in the uncoated portion located in one or more winding turns including the last winding turn. Therefore, the uncoated portion located in one or more winding turns including the last winding turn may have a low height like the uncoated portion that is not bent in the core side section (see A, A' in FIG. 4). According to such a structure of the uncoated portion, the uncoated portion located in one or more winding turns including the last winding turn does not need to be bent.

[0182] In the following, a structure will be described in which the uncoated portion is formed high up to the portion corresponding to the last winding turn and the uncoated portion is folded, however, it is of course possible that the uncoated portion located at one or more winding turns including the last winding turn is low like the uncoated portion on the core side and does not need to be folded.

[0183] Preferably, in the winding structure of the first electrode 40, the relative radial position R 1,1 to the first relative radial position R 1,k* The height of the plain area in the section up to the relative radial position R 1,k*+1 The height of the uncoated portion in the section from to relative radial position 1 may be lower than the height of the uncoated portion, and it does not have to be bent toward the core side.

[0184] In the winding structure of the first electrode 40, the relative radial position R 1,k*+1 The folded length of the plain part located at fd 1,k*+1 is the relative radial position R 1,1 Relative radial position R 1,k* Radial length r up to A Therefore, the cavity C in the core of the electrode assembly 80 can be located at a relative radial position R 2,k*+1 3 and 4. The bent portion of the non-coated portion 43a located in the section of relative radial position 1 is not shielded.

[0185] Preferably, in the winding structure of the second electrode 40′, the relative radial position R 2,1 to the first relative radial position R 2,k* The height of the plain area in the section up to the relative radial position R 2,k*+1 The height of the uncoated portion in the section from to relative radial position 1 may be lower than the height of the uncoated portion, and it does not have to be bent toward the core side.

[0186] In the winding structure of the second electrode 40′, the relative radial position R 2,k*+1 The folded length of the plain part located at fd 2,k*+1 is the relative radial position R 2,1 to the first relative radial position R 2,k* Length r' A’ Therefore, the cavity C in the core of the electrode assembly 80 can be located at a relative radial position R 2,k*+1Therefore, it is not blocked by the bent portion of the plain area located in the range of relative radial position 1.

[0187] 4 and 6, in the winding structure of the first electrode 40, the relative radial position R 1,k*+1 The second relative radial position R of the k@th winding turn preset from 1,k@ The uncoated portion in the section up to is divided into a plurality of segments 61, the height of which can increase stepwise or gradually toward the outer periphery.

[0188] In addition, in the winding structure of the first electrode 40, the relative radial position R of the preset k@+1-th winding turn 1,k@+1 The uncoated portion of the first electrode 40 is divided into a plurality of segments 61 from the relative radial position R 1,k@+1 to relative radial position 1 may be approximately the same.

[0189] 4 and 7, in the winding structure of the second electrode 40′, the relative radial position R 2,k*+1 The second relative radial position R of the k@th winding turn preset from 2,k@ The uncoated portion in the section up to is divided into a plurality of segments 61, the height of which can increase stepwise or gradually toward the outer periphery.

[0190] In addition, in the winding structure of the second electrode 40′, the relative radial position R of the preset k@+1-th winding turn 2,k@+1 The uncoated portion of the second electrode 40′ is divided into a plurality of segments 61 from the relative radial position R 2,k@+1 to relative radial position 1 may be approximately the same.

[0191] Preferably, in the winding structure of the first electrode 40, the uncoated portion 43a bent toward the core side is divided into a plurality of segments 61, and at least one of the height in the winding axial direction and the width in the winding direction of the plurality of segments 61 may increase stepwise from the core side to the outer periphery, either individually or for each group.

[0192] Similarly, in the winding structure of the second electrode 40', the uncoated portion 43a' bent toward the core side is divided into a plurality of segments 61, and at least one of the height in the winding axial direction and the width in the winding direction of the plurality of segments 61 may increase stepwise from the core side to the outer periphery, either individually or by group.

[0193] Desirably, when the folded portions of the plain portions 43a, 43a' are divided into a plurality of divided segments 61, each of the plurality of divided segments 61 can satisfy at least one of the following conditions: a width condition of 1 mm to 11 mm in the winding direction, a height condition of 2 mm to 10 mm in the winding axial direction, and a spacing pitch condition of 0.05 mm to 1 mm in the winding direction.

[0194] Preferably, a predetermined gap may be provided between the lower end (D4 in FIG. 5) of the cut groove of the divided piece 61 and the active material layer 42. Preferably, the gap may be 0.2 mm to 4 mm.

[0195] Preferably, the boundary between the active material layer 42 and the uncoated portion may be covered with an insulating coating layer 44. In the case of a structure in which the insulating coating layer 44 is formed, a predetermined gap may be provided between the lower end (D4 in FIG. 5) of the cut groove of the divided piece 61 and the insulating coating layer 44. Preferably, the gap may be 0.2 mm to 4 mm.

[0196] Referring to FIG. 4, when the folded portions of the uncoated portions 43a, 43a' are divided into a plurality of division segments 61, the division segments 61 form a plurality of division segment groups from the core side toward the outer periphery, and the division segments belonging to the same division segment group may have at least one of the width in the winding direction, the height in the winding axial direction, and the spacing pitch in the winding direction that is the same as each other.

[0197] Desirably, at least some of the multiple segment groups may be disposed on the same winding turn of the electrode assembly 80 .

[0198] The segments belonging to the same winding turn may belong to the same segment group.

[0199] The segments belonging to the same segment group may constitute the same winding turn.

[0200] The segments belonging to the same segment group may constitute a part of the same winding turn and a part of an adjacent winding turn.

[0201] The segments belonging to the same segment group may constitute the entirety of the same winding turn and a part of the adjacent winding turn.

[0202] The segments belonging to the same segment group may constitute the entirety of the same winding turn, part or all of the winding turn adjacent thereto on the core side, and part or all of the winding turn adjacent thereto on the outer circumferential side.

[0203] FIG. 8 is a partial cross-sectional view showing an electrode assembly with a radius of 22 mm included in a cylindrical battery of form factor 4680, in which the uncoated portion 43a of the first electrode 40 is bent from the outer periphery side to the core side to overlap 10 or more sheets, and the radial length of the relative radial position section is 25% or more based on the radius of the electrode assembly (a concept including the hollow portion of the core).

[0204] The radius of the hollow portion in the core of the electrode assembly is 4 mm. The uncoated portion 43a is divided into a number of segments along the winding direction. The segments are arranged from a winding turn located at a radius of 7 mm to a winding turn located at a radius of 22 mm of the electrode assembly. The height of the segments starts at 3 mm and increases by 1 mm for each 1 mm increase in radius, up to 6 mm, 7 mm, or 8 mm.

[0205] In Fig. 8, the top cross-sectional view shows an embodiment in which the height of the sub-segments increases from 3 mm to 8 mm from a radius of the electrode assembly of 7 mm to 12 mm, and remains constant at 8 mm from a radius of 13 mm to 22 mm. The middle cross-sectional view shows an embodiment in which the height of the sub-segments increases from 3 mm to 7 mm from a radius of the electrode assembly of 7 mm to 11 mm, and remains constant at 7 mm from a radius of 12 mm to 22 mm. The bottom cross-sectional view shows an embodiment in which the height of the sub-segments increases from 3 mm to 6 mm from a radius of the electrode assembly of 7 mm to 10 mm, and remains constant at 6 mm from a radius of 11 mm to 22 mm.

[0206] The discussion of the first electrode 40 with reference to FIG. 8 may be applied substantially equally to the second electrode.

[0207] 8, it can be seen that the number of overlapping layers of the uncoated portion 43a gradually increases from the outer periphery side toward the core side, and the maximum number of overlapping layers increases as the maximum height of the uncoated portion 43a increases.

[0208] For example, when the length (height) of the uncoated portion 43a increases from 3 mm to 8 mm, the number of overlapping layers of the uncoated portion 43a increases to 18 up to a section 7 mm from the outer circumferential surface of the electrode assembly, and the number of overlapping layers of the uncoated portion 43a is maintained constant at 18 from the section 7 mm beyond. In this embodiment, 18 is the maximum number of overlapping layers, which corresponds to the reference number of the present invention. The section where the maximum number of overlapping layers is maintained includes an 11 mm point corresponding to the midpoint of the radius of the electrode assembly. In addition, in the radius section adjacent to the core, the number of overlapping layers of the uncoated portion 43a decreases from 18 to 16. Of the relative radial position section (first region) where the number of overlapping layers of the uncoated portion 43a is 10 or more, the radial length of the relative radial position section (second region) where the number of overlapping layers of the uncoated portion 43a is uniform at a level of 16 to 18 is 8 mm, which is 36.4% of the radius of the electrode assembly, 22 mm.

[0209] The section in which the number of superposed layers is uniform may include a section in which the number of superposed layers is maintained at a maximum, and a section in the vicinity of the core in which the number of superposed layers decreases from the maximum value by a level of 1 to 3 layers.

[0210] As another example, when the length (height) of the uncoated portion 43a increases from 3 mm to 7 mm, the number of overlapping layers of the uncoated portion 43a increases to 15 up to a section 6 mm from the outer circumferential surface of the electrode assembly, and is maintained constant at 15 from the section 6 mm onward. In this embodiment, 15 is the maximum number of overlapping layers, which corresponds to the reference number of the present invention. The section where the maximum number of overlapping layers is maintained includes an 11 mm point corresponding to the midpoint of the radius of the electrode assembly. In addition, in a radius section adjacent to the core, the number of overlapping layers of the uncoated portion 43a decreases from 15 to 13. Among the relative radial position section (first region) where the number of overlapping layers of the uncoated portion 43a is 10 or more, the radial length of the relative radial position section (second region) where the number of overlapping layers of the uncoated portion 43a is uniform at a level of 13 to 15 is 9 mm, which is 40.9% of the radius of the electrode assembly, 22 mm.

[0211] As another example, when the length (height) of the uncoated portion 43a increases from 3 mm to 6 mm, the number of overlapping layers of the uncoated portion 43a increases to 12 up to a section of 5 mm from the outer circumferential surface of the electrode assembly, and is maintained constant at 12 layers after the section of 5 mm. In this embodiment, 12 is the maximum number of overlapping layers, which corresponds to the reference number of the present invention. The section where the maximum number of overlapping layers is maintained includes an 11 mm point corresponding to the midpoint of the radius of the electrode assembly. In addition, in the radius section adjacent to the core, the number of overlapping layers of the uncoated portion 43a decreases from 12 to 11. Among the relative radial position section (first region) where the number of overlapping layers of the uncoated portion 43a is 10 or more, the radial length of the relative radial position section (second region) where the number of overlapping layers of the uncoated portion 43a is uniform at a level of 11 to 12 is 10 mm, which is 45.5% of the radius of the electrode assembly, 22 mm.

[0212] According to the embodiment, when the maximum length (height) of the uncoated portion 43a is 6mm to 8mm, the length of the section where the number of overlapping layers gradually increases increases from 5mm to 7mm as the maximum length (height) of the uncoated portion 43a increases (higher). Also, the length of the section where the number of overlapping layers is uniform increases from 8mm to 10mm as the maximum length (height) of the uncoated portion 43a decreases (lower). In particular, the ratio of the radial length of the relative radial position section where the number of overlapping layers of the uncoated portion 43a is uniform and is 10 or more satisfies the condition of 25% or more based on the radius of the electrode assembly.

[0213] Compared to the above-described embodiment, when the maximum length (height) of the uncoated portion 43a is between 4 mm and 5.5 mm, the ratio of the radial length of the relative radial position section in which the number of overlapping layers of the uncoated portion 43a is uniformly maintained at 10 or more slightly exceeds 25%, and the number of overlapping layers is maintained at a level of 10 to 12.

[0214] Unlike the above-described embodiment, if the maximum length (height) of the non-coated portion 43a is 4 mm or less, there will be no section in which the number of overlapping layers of the non-coated portion 43a is 10 or more.

[0215] On the other hand, if the folded surface is formed under constant conditions without changing the length (height) of the uncoated portion 43a, the ratio of the radial length of the relative radial position section where the number of overlapping layers of the uncoated portion 43a is maintained uniform when the number of overlapping layers is 10 or more decreases significantly, making it difficult to satisfy the condition of 25% or more.

[0216] For example, if the length (height) of the uncoated portion 43a is constant and is 5.5 mm or more, and the folded surface is formed in a constant state, the ratio of the radial length of the relative radial position section where the number of overlapping layers of the uncoated portion 43a is maintained uniformly when the number of overlapping layers is 10 or more may be less than 25%.

[0217] As shown in Figure 4, if the height of the uncoated portion increases from the core side toward the outer periphery and is maintained constant from a certain radius point, even if the height of the uncoated portion is low at 3mm in the radius section adjacent to the core, the height of the uncoated portion can be gradually or stepwise increased to 6mm, 7mm, or 8mm, or even 9mm or 10mm along the centrifugal direction, thereby ensuring a wide area where the number of overlapping layers exceeds the minimum number (10) and is maintained uniformly at the standard number (maximum value). For reference, 10mm corresponds to the maximum design height of the uncoated portion. The height of the uncoated portion can be gradually or stepwise increased every time the radius increases by 1mm or every time the number of winding turns increases at a certain interval.

[0218] Various electrode assembly structures according to the embodiments (variations) of the present invention are applicable to jelly-roll type cylindrical batteries.

[0219] Desirably, the cylindrical battery may be, for example, a cylindrical battery having a form factor ratio (defined as the diameter divided by the height of a cylindrical battery, i.e., the ratio of height (H) to diameter (Φ)) greater than about 0.4.

[0220] Here, the form factor refers to a value indicating the diameter and height of a cylindrical battery. A cylindrical battery according to an embodiment of the present invention may be, for example, a 46110 battery, a 4875 battery, a 48110 battery, a 4880 battery, or a 4680 battery. In the value indicating the form factor, the first two digits indicate the diameter of the battery, and the remaining digits indicate the height of the battery.

[0221] When an electrode assembly having a tabless structure is applied to a cylindrical battery with a form factor ratio exceeding 0.4, the stress applied in the radial direction when the plain part is bent is large, and the plain part is easily broken. Also, when welding a current collector to the bent surface of the plain part, the number of overlapping layers of the plain part must be increased sufficiently to ensure sufficient welding strength and reduce resistance. These requirements can be achieved by the electrode and electrode assembly according to the embodiment (variant) of the present invention.

[0222] A battery according to one embodiment of the present invention may be a generally cylindrical battery having a diameter of about 46 mm, a height of about 110 mm, and a form factor ratio of 0.418.

[0223] Another embodiment of the battery may be a generally cylindrical battery having a diameter of about 48 mm, a height of about 75 mm, and a form factor ratio of 0.640.

[0224] In yet another embodiment, the battery may be a generally cylindrical battery having a diameter of about 48 mm, a height of about 110 mm, and a form factor ratio of 0.436.

[0225] In yet another embodiment, the battery may be a generally cylindrical battery having a diameter of about 48 mm, a height of about 80 mm, and a form factor ratio of 0.600.

[0226] In yet another embodiment, the battery may be a generally cylindrical battery having a diameter of about 46 mm, a height of about 80 mm, and a form factor ratio of 0.575.

[0227] Conventionally, batteries with a form factor ratio of about 0.4 or less have been used. That is, conventionally, for example, 1865 batteries, 2170 batteries, etc. have been used. In the case of an 1865 battery, the diameter is about 18 mm, the height is about 65 mm, and the form factor ratio is 0.277. In the case of a 2170 battery, the diameter is about 21 mm, the height is about 70 mm, and the form factor ratio is 0.300.

[0228] Hereinafter, a cylindrical battery according to an embodiment of the present invention will be described in detail.

[0229] FIG. 9 is a cross-sectional view of a cylindrical battery 190 according to an embodiment of the present invention taken along the Y-axis direction.

[0230] Referring to FIG. 9, a cylindrical battery 190 according to one embodiment of the present invention includes an electrode assembly 80 including a first electrode, a separator, and a second electrode, a battery housing 142 that houses the electrode assembly 80, and a seal 143 that seals an open portion of the battery housing 142.

[0231] The battery housing 142 is a cylindrical container with an opening at the top. The battery housing 142 is made of a conductive metal material such as aluminum or steel. The battery housing 142 accommodates the electrode assembly 80 in the inner space through the top opening, and also accommodates an electrolyte.

[0232] The electrolyte is A + B - In this case, the salt may have the structure: + Li + , Na + , K + or a combination thereof. - 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 - 、(SF5 ) 3 C - , (CF 3 SO 2 ) 3 C - , C.F. 3 (CF 2 ) 7 SO 3 - , C.F. 3 CO 2 - , C.H. 3 CO 2 - , SCN - and (CF 3 CF 2 SO 2 ) 2 N - The anion includes one or more anions selected from the group consisting of:

[0233] The electrolyte may be dissolved in an organic solvent for use. The organic solvent may be propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), γ-butyrolactone, or a mixture thereof.

[0234] The electrode assembly 80 may have a jelly roll structure. The electrode assembly 80 may be manufactured by sequentially stacking a lower separator, a first electrode, an upper separator, and a second electrode at least once, and winding the stack around a winding center C, as shown in FIG.

[0235] The first electrode and the second electrode have different polarities. That is, if one has a positive polarity, the other has a negative polarity. At least one of the first electrode and the second electrode may have an electrode structure according to the above-mentioned embodiment (variant). Also, the other of the first electrode and the second electrode may have a conventional electrode structure or an electrode structure according to the embodiment (variant).

[0236] An uncoated portion 43a of the first electrode and an uncoated portion 43a' of the second electrode protrude from the top and bottom of the electrode assembly 80, respectively.

[0237] The sealing body 143 may include a cap plate 143a, a first gasket 143b having insulating properties and providing airtightness between the cap plate 143a and the battery housing 142, and a connecting plate 143c electrically and mechanically connected to the cap plate 143a.

[0238] The cap plate 143a is a part made of a conductive metal material and covers the upper opening of the battery housing 142. The cap plate 143a is electrically connected to the uncoated portion 43a of the first electrode and is electrically insulated from the battery housing 142 via a first gasket 143b. Therefore, the cap plate 143a can function as a first electrode terminal of the cylindrical battery 190.

[0239] The cap plate 143a is placed on a beading portion 147 formed on the battery housing 142 and fixed by a crimping portion 148. A first gasket 143b may be interposed between the cap plate 143a and the crimping portion 148 to ensure airtightness of the battery housing 142 and to provide electrical insulation between the battery housing 142 and the cap plate 143a. The cap plate 143a may have a protrusion 143d formed to protrude upward from the center thereof.

[0240] The battery housing 142 is electrically connected to the uncoated portion 43a' of the second electrode. Therefore, the battery housing 142 has the same polarity as the second electrode. If the second electrode has a negative polarity, the battery housing 142 also has a negative polarity.

[0241] The battery housing 142 has a beading portion 147 and a crimping portion 148 at the upper end. The beading portion 147 is formed by pressing around the outer periphery of the battery housing 142. The beading portion 147 prevents the electrode assembly 80 accommodated inside the battery housing 142 from slipping out of the upper opening of the battery housing 142, and can function as a support on which the sealing body 143 is placed.

[0242] The crimping portion 148 is formed on the upper portion of the beading portion 147. The crimping portion 148 is extended and bent to enclose the outer circumferential surface of the cap plate 143a disposed on the beading portion 147 and a part of the upper surface of the cap plate 143a.

[0243] The cylindrical battery 190 may further include a first current collector 30 and / or a second current collector 31 and / or an insulator 146 .

[0244] The first current collecting plate 30 is coupled to an upper portion of the electrode assembly 80. The first current collecting plate 30 is made of a conductive metal material such as aluminum, copper, nickel, etc., and is electrically connected to a bent surface formed by bending the uncoated portion 43a of the first electrode. A lead 149 may be connected to the first current collecting plate 30. The lead 149 may extend upwardly of the electrode assembly 80 and be coupled to the connection plate 143c, or may be directly coupled to a lower surface of the cap plate 143a. The lead 149 may be coupled to other components by welding.

[0245] Preferably, the first current collecting plate 30 may be integrally formed with the lead 149. In this case, the lead 149 may be in the form of a long plate extending outward from the center of the first current collecting plate 30.

[0246] The bent surface of the non-coating portion 43a may be joined to the first current collecting plate 30 by, for example, laser welding. Laser welding may be performed by partially melting the base material of the current collecting plate. Laser welding may be replaced by resistance welding, ultrasonic welding, etc.

[0247] At least a part of the welded region of the first current collector plate 30 can overlap with a section (first region) of the uncoated portion 43a where the number of overlapping layers is 10 or more on the bent surface of the uncoated portion 43a.

[0248] Desirably, at least a portion of the welded area of ​​the first current collecting plate 30 may overlap with a section (second area) where the number of overlapping layers of the uncoated portion 43a is 10 or more on the folded surface of the uncoated portion 43a and is uniformly maintained at a standard number along the radial direction.

[0249] The radius section corresponding to the second region is 25% or more based on the radius of the electrode assembly. The reference number corresponds to the maximum number of overlapping layers of the non-coating portion 43a. The overlapping ratio between the welding region and the second region may be at least 50% or more.

[0250] A second current collecting plate 31 may be coupled to a lower surface of the electrode assembly 80. One surface of the second current collecting plate 31 may be coupled by welding to a bent surface formed by bending the uncoated portion 43a' of the second electrode, and the other surface may be coupled by welding to an inner bottom surface of the battery housing 142. The coupling structure between the second current collecting plate 31 and the uncoated portion 43a' of the second electrode may be substantially the same as the coupling structure between the first current collecting plate 30 and the uncoated portion 43a of the first electrode.

[0251] The insulator 146 may cover the first current collecting plate 30. The insulator 146 may cover the first current collecting plate 30 on the upper surface of the first current collecting plate 30, thereby preventing direct contact between the first current collecting plate 30 and the inner peripheral surface of the battery housing 142.

[0252] The insulator 146 has a lead hole 151 through which the lead 149 extending upward from the first current collecting plate 30 is pulled out. The lead 149 is pulled out upward through the lead hole 151 and coupled to the lower surface of the connection plate 143c or the lower surface of the cap plate 143a.

[0253] The peripheral region of the insulator 146 may be interposed between the first current collecting plate 30 and the beading portion 147 to fix the combination of the electrode assembly 80 and the first current collecting plate 30. This limits the movement of the combination of the electrode assembly 80 and the first current collecting plate 30 in the height direction of the battery 190, thereby improving the assembly stability of the battery 190.

[0254] The insulator 146 may be made of an insulating polymer resin. In one example, the insulator 146 may be made of polyethylene, polypropylene, polyimide, or polybutylene terephthalate.

[0255] The battery housing 142 may further include a venting portion 152 formed on the lower surface thereof. The venting portion 152 corresponds to a region on the lower surface of the battery housing 142 that is thinner than the surrounding region. The venting portion 152 is structurally weaker than the surrounding region. Therefore, if an abnormality occurs in the cylindrical battery 190 and the internal pressure increases above a certain level, the venting portion 152 may burst and gas generated inside the battery housing 142 may be discharged to the outside.

[0256] The vents 152 may be formed continuously or discontinuously in a circle on the underside of the battery housing 142. In a variation, the vents 152 may be formed in a linear pattern or other patterns.

[0257] FIG. 10 is a cross-sectional view of a cylindrical battery 200 according to another embodiment of the present invention taken along the Y-axis direction.

[0258] 10, a cylindrical battery 200 is different from the cylindrical battery 190 shown in FIG. 9 in that the structure of the electrode assembly 80 is substantially the same, but other structures except for the electrode assembly have been changed.

[0259] Specifically, the cylindrical battery 200 includes a battery housing 171 having a rivet terminal 172 penetrating therethrough. The rivet terminal 172 is attached to a closed surface (top surface in the drawing) of the battery housing 171. The rivet terminal 172 is riveted into a through hole of the battery housing 171 with an insulating second gasket 173 interposed therebetween. The rivet terminal 172 is exposed to the outside in the direction opposite to the direction of gravity.

[0260] The rivet terminal 172 includes a terminal exposure portion 172a and a terminal insertion portion 172b. The terminal exposure portion 172a is exposed to the outside of the closed surface of the battery housing 171. The terminal exposure portion 172a may be located at an approximately central portion of the closed surface of the battery housing 171. The maximum diameter of the terminal exposure portion 172a may be larger than the maximum diameter of a through hole formed in the battery housing 171. The terminal insertion portion 172b may penetrate approximately the central portion of the closed surface of the battery housing 171 and be electrically connected to the uncoated portion 43a of the first electrode. The terminal insertion portion 172b may be rivet-coupled to the inner surface of the battery housing 171. That is, the peripheral portion of the terminal insertion portion 172b may have a shape bent toward the inner surface of the battery housing 171. The maximum diameter of the peripheral portion of the terminal insertion portion 172b may be larger than the maximum diameter of the through hole of the battery housing 171.

[0261] A lower end surface of the terminal insertion portion 172b is substantially flat and may be welded to the first current collecting plate 30 connected to the uncoated portion 43a of the first electrode. An insulator 174 made of an insulating material may be interposed between the first current collecting plate 30 and the inner surface of the battery housing 171. The insulator 174 covers an upper portion of the first current collecting plate 30 and an upper peripheral edge portion of the electrode assembly 80. This prevents the uncoated portion on the outer periphery of the electrode assembly 80 from coming into contact with the inner surface of the battery housing 171 having the opposite polarity, causing a short circuit.

[0262] The terminal insertion portion 172b of the rivet terminal 172 may be laser-welded to the first current collecting plate 30 through the insulator 174. The laser welding may be replaced by ultrasonic welding, resistance welding, or the like.

[0263] At least a part of the welded region of the first current collector plate 30 can overlap with a section (first region) of the uncoated portion 43a where the number of overlapping layers is 10 or more on the bent surface of the uncoated portion 43a.

[0264] Desirably, at least a portion of the welded area of ​​the first current collecting plate 30 may overlap with a section (second area) where the number of overlapping layers of the uncoated portion 43a is 10 or more on the folded surface of the uncoated portion 43a and is uniformly maintained at a standard number along the radial direction.

[0265] The radius section corresponding to the second region is 25% or more based on the radius of the electrode assembly. The reference number corresponds to the maximum number of overlapping layers of the non-coating portion 43a. The overlapping ratio between the welding region and the second region may be at least 50% or more.

[0266] The second gasket 173 is interposed between the battery housing 171 and the rivet terminal 172 to prevent electrical contact between the battery housing 171 and the rivet terminal 172, which have opposite polarity. This allows the upper surface of the battery housing 171, which has a substantially flat shape, to function as a second electrode terminal of the cylindrical battery 200.

[0267] The second gasket 173 includes a gasket exposing portion 173a and a gasket inserting portion 173b. The gasket exposing portion 173a is interposed between the terminal exposing portion 172a of the rivet terminal 172 and the battery housing 171. The gasket inserting portion 173b is interposed between the terminal inserting portion 172b of the rivet terminal 172 and the battery housing 171. The gasket inserting portion 173b may be deformed during riveting of the terminal inserting portion 172b and may be closely attached to the inner surface of the battery housing 171. The second gasket 173 may be made of, for example, a polymer resin having insulating properties.

[0268] The gasket exposing portion 173a of the second gasket 173 may have a shape extended to cover an outer circumferential surface of the terminal exposing portion 172a of the rivet terminal 172. When the second gasket 173 covers the outer circumferential surface of the rivet terminal 172, it is possible to prevent a short circuit from occurring during the process of connecting an electrical connection component such as a bus bar to the upper surface of the battery housing 171 and / or the rivet terminal 172. Although not shown, the gasket exposing portion 173a may have a shape extended to cover not only the outer circumferential surface of the terminal exposing portion 172a but also a part of the upper surface.

[0269] When the second gasket 173 is made of a polymer resin, the second gasket 173 may be joined to the battery housing 171 and the rivet terminal 172 by thermal sealing. In this case, airtightness is enhanced at the joining interface between the second gasket 173 and the rivet terminal 172 and at the joining interface between the second gasket 173 and the battery housing 171. Meanwhile, when the gasket exposing portion 173a of the second gasket 173 has a shape that extends to the upper surface of the terminal exposing portion 172a, the rivet terminal 172 may be joined integrally with the second gasket 173 by insert injection.

[0270] A region 175 on the upper surface of the battery housing 171 excluding the region occupied by the rivet terminal 172 and the second gasket 173 corresponds to a second electrode terminal having a polarity opposite to that of the rivet terminal 172 .

[0271] The second current collecting plate 31 is coupled to the lower part of the electrode assembly 80. The second current collecting plate 31 is made of a conductive metal material such as aluminum, steel, copper, nickel, etc., and is electrically connected to the uncoated portion 43a' of the second electrode.

[0272] Desirably, the second current collecting plate 31 is electrically connected to the battery housing 171. Therefore, the second current collecting plate 31 may be fixed with at least a portion of a peripheral portion interposed between the inner surface of the battery housing 171 and the first gasket 178b. In one example, at least a portion of a peripheral portion of the second current collecting plate 31 may be fixed to the beading portion 180 by welding while being supported on a lower end surface of the beading portion 180 formed at the lower end of the battery housing 171. In a modified embodiment, at least a portion of a peripheral portion of the second current collecting plate 31 may be directly welded to the inner wall surface of the battery housing 171.

[0273] Preferably, the second current collecting plate 31 and the bent surface of the non-coating portion 43a' are joined by welding, for example, laser welding, which can be substituted by ultrasonic welding, resistance welding, or the like.

[0274] The welded region of the second current collector plate 31 can at least partially overlap a section (first region) of the uncoated portion 43a' where the number of overlapping layers is 10 or more on the bent surface of the uncoated portion 43a'.

[0275] Desirably, at least a portion of the welding area of ​​the second current collecting plate 31 may overlap with a section (second area) where the number of overlapping layers of the uncoated portion 43a' is 10 or more on the folded surface of the uncoated portion 43a' and is uniformly maintained at a standard number along the radial direction.

[0276] The radius section corresponding to the second region is 25% or more based on the radius of the electrode assembly. The reference number corresponds to the maximum number of overlapping layers of the non-coating portion 43a'. The overlapping ratio between the welding region and the second region may be at least 50% or more.

[0277] The sealing body 178 that seals the lower open end of the battery housing 171 includes a cap plate 178a and a first gasket 178b. The first gasket 178b electrically separates the cap plate 178a from the battery housing 171. A crimping portion 181 fixes the periphery of the cap plate 178a and the first gasket 178b together. The cap plate 178a is provided with a venting portion 179. The configuration of the venting portion 179 is substantially the same as that of the above-described embodiment (variant).

[0278] Preferably, the cap plate 178a is made of a conductive metal material. However, the cap plate 178a does not have electrical polarity because the first gasket 178b is interposed between the cap plate 178a and the battery housing 171. The seal 178 seals the open end of the lower part of the battery housing 171 and functions to discharge gas when the internal pressure of the battery 200 increases above a critical value.

[0279] Preferably, the rivet terminal 172 electrically connected to the uncoated portion 43a of the first electrode is used as the first electrode terminal. Also, a portion 175 of the upper surface of the battery housing 171 electrically connected to the uncoated portion 43a' of the second electrode through the second current collector 31, excluding the rivet terminal 172, is used as a second electrode terminal having the opposite polarity to the first electrode terminal. In this way, when the two electrode terminals are located at the upper portion of the cylindrical battery 200, it is possible to arrange electrical connection parts such as a bus bar only on one side of the cylindrical battery 200. This can simplify the structure of the battery pack and improve the energy density. Also, since the portion 175 used as the second electrode terminal has a substantially flat shape, it is possible to secure a sufficient joining area when joining electrical connection parts such as a bus bar. As a result, the cylindrical battery 200 can reduce the resistance at the joining portion of the electrical connection parts to a desired level.

[0280] In the present invention, even if the uncoated portions 43a, 43a' are folded toward the core side, the cavity 112 of the core C of the electrode assembly 80 is not closed and can be open to the upper side.

[0281] By designing the height of the uncoated portions 43a, 43a', particularly the height of the uncoated portion on the core side, to be low for each relative radial position based on the winding turn index of the first electrode and the second electrode, the cavity 112 in the core of the electrode assembly 80 is not blocked even if the uncoated portion near the core of the electrode assembly 80 is bent.

[0282] If the cavity 112 is not blocked, the electrolyte injection process can be performed without any problems, and the efficiency of the electrolyte injection can be improved. Also, by inserting a welding jig through the cavity 112, the welding process between the current collector 31 in Fig. 9 and the bottom surface of the battery housing 142 or between the current collector 30 in Fig. 10 and the rivet terminal 172 can be easily performed.

[0283] When the uncoated portions 43a, 43a' have a divided structure, by adjusting the width and / or height and / or spacing pitch of the divided pieces to satisfy the numerical range of the above-mentioned embodiment, when the divided pieces are bent, the divided pieces overlap each other to an extent that sufficient welding strength can be ensured, and no open space (gap) is formed on the bent surface.

[0284] The cylindrical battery according to the above-described embodiment (variation) can be used to manufacture a battery pack.

[0285] FIG. 11 is a diagram illustrating a schematic configuration of a battery pack according to an embodiment of the present invention.

[0286] 11, a battery pack 300 according to an embodiment of the present invention includes an assembly of electrically connected cylindrical batteries 301, and a pack housing 302 that accommodates the cylindrical batteries 301. The cylindrical battery 301 may be any one of the batteries 190 and 200 according to the above-described embodiments (variants). For convenience of illustration, components such as a bus bar for electrical connection of the cylindrical battery 301, a cooling unit, and external terminals are not shown.

[0287] The battery pack 300 may be installed in a vehicle. The vehicle may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The vehicle may include a four-wheeled vehicle or a two-wheeled vehicle.

[0288] FIG. 12 is a diagram for explaining a vehicle including the battery pack 300 of FIG.

[0289] 12, an automobile V according to an embodiment of the present invention includes a battery pack 300 according to an embodiment of the present invention. The automobile V operates by receiving power from the battery pack 300 according to an embodiment of the present invention.

[0290] According to one aspect of the present invention, when the uncoated portions exposed at both ends of the electrode assembly are bent, a sufficient area is secured in the radial direction of the electrode assembly in which 10 or more uncoated portions overlap, thereby preventing damage to the separator and active material layer even when the welding output is increased.

[0291] In addition, according to one aspect of the present invention, by improving the structure of the uncoated portion adjacent to the core of the electrode assembly, it is possible to prevent the cavity in the core of the electrode assembly from being blocked when the uncoated portion is bent, thereby facilitating the electrolyte injection process and the welding process of the battery housing and the current collector plate.

[0292] In addition, according to one aspect of the present invention, an electrode assembly having improved energy density and reduced resistance can be provided by directly welding a bent surface of an uncoated portion to a current collecting plate instead of using a strip-shaped electrode tab.

[0293] In addition, according to one aspect of the present invention, it is possible to provide a cylindrical battery having a structure with low internal resistance and improved welding strength between a current collector plate and an uncoated portion, and a battery pack and a vehicle including the same.

[0294] As described above, the present invention has been described using limited embodiments and drawings. However, the present invention is not limited thereto, and it goes without saying that various modifications and variations can be made by a person having ordinary knowledge in the technical field to which the present invention belongs within the technical spirit of the present invention and the equivalent scope of the claims. [Explanation of symbols]

[0295] 10 positive electrode 11 Negative electrode 12 Separation membrane 20 Current collector 21 Active material 22 Plain area 30 Current collector, first current collector 31 Current collector, second current collector 32 Plain section 33 Cavity 40 Electrode assembly, electrode 41 Current collector 42 Active material layer 42 Active material coating layer 43 Plain section 44 Insulating coating layer 61 min section 80 Electrode assembly 112 Cavity 142 Battery housing 143 Sealed body 146 Insulators 147 Beading Section 148 Crimping section 149 Leads 151 Lead hole 152 Venting section 171 Battery housing 172 Rivet terminal 173 Second Gasket 174 Insulators 178 Sealed body 179 Venting Section 180 Beading section 181 Crimping section 190 Cylindrical Battery 200 Cylindrical Battery 300 Battery Pack 301 Cylindrical Battery 302 Pack Housing

Claims

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 around a single axis to define a core and an outer circumferential surface, At least one of the first electrode and the second electrode includes a non-coated portion at a long side end, At least a portion of the uncoated portion is exposed to the outside of the separator along a longitudinal direction of the electrode assembly, At least a portion of the uncoated portion is bent in a radial direction of the electrode assembly to form a bent surface, The folded surface has a first region in which the number of overlapping layers of the non-coating portion is equal to or greater than the minimum number, the first region extending along the radial direction, The total number of winding turns of the electrode including the uncoated portion is n ｉ Then, the winding turn index k at the kth winding turn position is expressed as the total number of winding turns n ｉ The value obtained by dividing the value by the winding turn index k is the relative radial position R ｉ，ｋ Define it as: the ratio of the length of the radial section of Ri,k that satisfies the condition that the number of overlapping layers of the non-coating portion is 10 or more to the radius of the electrode assembly is at least 25%; When i is 1, it means that it is a factor for the first electrode, when i is 2, it means that it is a factor for the second electrode, when i is 1, it means that n １ means the total number of turns of the first electrode, and when i is 2, n ２ means the total number of winding turns of the second electrode, k is a natural number from 1 to n, The number of overlapping layers of the uncoated portion is defined as the number of uncoated portions intersecting an imaginary line drawn at one point on the bent surface in parallel with an axial direction of the electrode assembly.

2. The electrode assembly of claim 1 , wherein the bent surface is formed by bending the uncoated portion based on a predetermined bending point (D4).

3. The electrode assembly of claim 1 , wherein the minimum number is ten.

4. the folded surface includes a second region in which the number of overlapping layers of the non-coating portion is maintained constant at a reference number along a radial direction, The electrode assembly of claim 1 , wherein the second region is included in the first region.

5. The electrode assembly according to claim 4 , wherein the reference number is equal to or greater than a minimum number.

6. The electrode assembly of claim 4 , wherein the first region includes a first varying region in which the number of overlapping layers gradually increases in a radial direction, and a second varying region in which the number of overlapping layers gradually decreases in a radial direction.

7. The electrode assembly of claim 6 , wherein the second region is between the first and second variation regions.

8. 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 around a single axis to define a core and an outer circumferential surface, At least one of the first electrode and the second electrode includes a non-coated portion at a long side end, At least a portion of the uncoated portion is exposed to the outside of the separator along a longitudinal direction of the electrode assembly, At least a portion of the uncoated portion is bent in a radial direction of the electrode assembly to form a bent surface, the folded surface includes a second region in which the number of overlapping layers of the non-coating portion is maintained substantially constant at a reference number along a radial direction, The total number of winding turns of the electrode including the uncoated portion is n ｉ Then, the winding turn index k at the kth winding turn position is expressed as the total number of winding turns n ｉ The value obtained by dividing the value by the winding turn index k is the relative radial position R ｉ，ｋ Define it as: The reference number is 10 or more, a ratio of a length of a radial section of the relative radial position R i,k where the number of overlapping layers of the non-coating portion satisfies the reference number is at least 25% with respect to a radius of the electrode assembly; When i is 1, it means that it is a factor for the first electrode, when i is 2, it means that it is a factor for the second electrode, when i is 1, it means that n １ means the total number of turns of the first electrode, and when i is 2, n ２ means the total number of winding turns of the second electrode, k is a natural number from 1 to n, The number of overlapping layers of the uncoated portion is defined as the number of uncoated portions intersecting an imaginary line drawn at one point on the bent surface in parallel with an axial direction of the electrode assembly.

9. The thickness of the first electrode and the second electrode is 80 μm to 250 μm; 9. The electrode assembly according to claim 1, wherein the distance between the uncoated portions located on adjacent winding turns in the radial direction of the electrode assembly is 200 μm to 500 μm.

10. In the winding structure of the electrode including the uncoated portion, the relative radial position R of the first winding turn ｉ，１ The first relative radial position R of the k*th winding turn preset from ｉ，ｋ＊ The height of the plain part in the section up to the k*+1th winding turn is the relative radial position R ｉ，ｋ＊＋１ from the relative radial position R ｉ，ｌａｓｔ It is lower than the height of the plain area in the section up to The relative radial position R ｉ，ｌａｓｔ is the relative radial position R ｉ，ｋ＊＋１ 9. The electrode assembly according to claim 1, wherein the folded uncoated portion is located on the outermost winding turn relative to the outermost winding turn.

11. Relative Radial Position R ｉ，ｌａｓｔ The electrode assembly of claim 10 , wherein:

12. Relative Radial Position R ｉ，ｌａｓｔ is R ｉ，ｎｉ－ｐ 11. The electrode assembly of claim 10, wherein p is the number of winding turns without uncoated portions that form a folded surface, including the outermost winding turns.

13. In the winding structure of the electrode including the uncoated portion, the relative radial position R of the first winding turn ｉ，１ The first relative radial position R of the k*th winding turn preset from ｉ，ｋ＊ 9. The electrode assembly according to claim 1, wherein a height of the uncoated portion in the section from to is lower than a folded surface formed by overlapping the folded uncoated portions.

14. In the winding structure of the electrode including the uncoated portion, the relative radial position R of the first winding turn ｉ，１ The first relative radial position R of the k*th winding turn preset from ｉ，ｋ＊ The electrode assembly according to claim 10 , wherein the height of the uncoated portion in the section up to is lower than a folded surface formed by overlapping the folded uncoated portions.

15. In the winding structure of the electrode including the uncoated portion, the relative radial position R of the first winding turn ｉ，１ The first relative radial position R of the k*th winding turn from ｉ，ｋ＊ The electrode assembly according to claim 1 , wherein the uncoated portion is not folded toward the core of the electrode assembly in the section up to .

16. In the winding structure of the electrode including the uncoated portion, the relative radial position R of the first winding turn ｉ，１ The first relative radial position R of the k*th winding turn from ｉ，ｋ＊ The electrode assembly of claim 10 , wherein the uncoated portion is not folded toward the core of the electrode assembly in the section up to .

17. The electrode assembly according to claim 1 , wherein a folded portion of the uncoated portion of the first electrode or the uncoated portion of the second electrode is divided into a plurality of segments.

18. 18. The electrode assembly of claim 17, wherein each of the plurality of segments is a rectangle, a trapezoid, a triangle, a parallelogram, a semicircle, or a semi-ellipse.

19. The electrode assembly of claim 17 , wherein each of the plurality of segments is a trapezoid, and a lower interior angle of the trapezoid increases from a core side to an outer periphery side of the plurality of segments individually or for each group.

20. In the winding structure of the electrode including the uncoated portion, the relative radial position R of the k*+1-th winding turn ｉ，ｋ＊＋１ The folded length of the plain part in fd ｉ，ｋ＊＋１ is the relative radial position R of the first winding turn ｉ，１ k*th relative radial position R ｉ，ｋ＊ The electrode assembly of claim 10, wherein the radial length is equal to or less than the radial length up to the

21. In the winding structure of the electrode including the uncoated portion, the cavity in the core of the electrode assembly is located at the relative radial position R of the k*+1th winding turn. ｉ，ｋ＊＋１ from the relative radial position R ｉ，ｌａｓｔ is not shielded by the bent portion of the plain area located in the section up to The relative radial position R ｉ，ｌａｓｔ is the relative radial position R ｉ，ｋ＊＋１ 11. The electrode assembly according to claim 10, wherein the folded uncoated portion is located on the outermost winding turn relative to the outermost winding turn.

22. In the winding structure of the electrode including the uncoated portion, the relative radial position R of the k*+1-th winding turn ｉ，ｋ＊＋１ The second relative radial position R of the k@th winding turn preset from ｉ，ｋ＠ 11. The electrode assembly according to claim 10, wherein the uncoated portion in the section up to is divided into a plurality of segments, the heights of which increase stepwise or gradually toward the outer periphery.

23. In the winding structure of the electrode including the uncoated portion, a relative radial position R of a predetermined k@+1-th winding turn ｉ，ｋ＠＋１ from the relative radial position R ｉ，ｌａｓｔ The uncoated portion of the first electrode is divided into a plurality of segments, and the heights of the plurality of segments are different from each other by the relative radial position R ｉ，ｋ＠＋１ from the relative radial position R ｉ，ｌａｓｔ are almost identical up to The relative radial position R ｉ，ｌａｓｔ is the relative radial position R ｉ，ｋ＊＋１ 23. The electrode assembly of claim 22, wherein the folded uncoated portion is located on the outermost winding turn relative to the outermost winding turn.

24. The relative radial position R ｉ，ｌａｓｔ The electrode assembly of claim 23 , wherein:

25. The relative radial position R ｉ，ｌａｓｔ is R ｉ，ｎ１－ｐ 24. The electrode assembly of claim 23, wherein p is the number of winding turns without uncoated portions that form a folded surface, including the outermost winding turns.

26. 9. The electrode assembly according to claim 1, wherein in the winding structure of the electrode including the uncoated portion, the uncoated portion bent toward the core side is divided into a plurality of segments, and at least one of the height in the winding axial direction and the width in the winding direction of the plurality of segments increases stepwise from the core side to the outer periphery individually or for each group.

27. The electrode assembly according to claim 17, wherein when the folded portion of the uncoated portion is divided into a plurality of segments, each of the plurality of segments satisfies at least one of the following conditions: a width condition of 1 mm to 11 mm in the winding direction, a height condition of 2 mm to 10 mm in the winding axial direction, and a spacing pitch condition of 0.05 mm to 1 mm in the winding direction.

28. The electrode assembly according to claim 17, wherein a predetermined gap is provided between a lower end (D4) of the cut groove of the divided piece and the active material layer.

29. an insulating coating layer is formed at the boundary between the non-coated portion and the active material layer; 18. The electrode assembly according to claim 17, wherein a predetermined gap is provided between the lower end (D4) of the cutting groove of the divided piece and the insulating coating layer.

30. The electrode assembly of claim 28, wherein the gap is between 0.2 mm and 4 mm.

31. The electrode assembly of claim 17, wherein when the folded portion of the uncoated portion is divided into a plurality of segments, the plurality of segments form a plurality of segment groups from the core side toward the outer periphery, and the segments belonging to the same segment group have at least one element of the width in the winding direction, the height in the winding axial direction, and the separation pitch in the winding direction that is the same as each other.

32. The electrode assembly according to claim 31 , wherein in the segments belonging to the same segment group, the one or more elements that are the same increase stepwise from the core side toward the outer periphery side.

33. The electrode assembly of claim 31 , wherein at least some of the plurality of segment groups are disposed on the same winding turn of the electrode assembly.

34. 32. The electrode assembly of claim 31, wherein the same winding turn belongs to one segment group.

35. 32. The electrode assembly according to claim 31, wherein the segments belonging to the same segment group constitute a part or all of the same winding turn and a part of an adjacent winding turn.

36. The electrode assembly of claim 31, wherein the segments belonging to the same segment group constitute all of the same winding turn, some or all of the winding turn adjacent to it on the core side, and some or all of the winding turn adjacent to it on the outer circumferential side.

37. 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 around one axis to define a core and an outer circumferential surface, the electrode assembly including a non-coated portion exposed to the outside of the separator along a longitudinal direction of the electrode assembly at a long side end of at least one of the first electrode and the second electrode, at least a portion of the non-coated portion being bent in a radial direction of the electrode assembly to form a bent surface, the bent surface including a region in which a number of overlapping layers of the non-coated portion is maintained constant at a reference number along the radial direction; a battery housing in which the electrode assembly is housed and which is electrically connected to one of the first electrode and the second electrode and has a first polarity; a seal for sealing an open end of the battery housing; a terminal electrically connected to the other of the first electrode and the second electrode, the terminal having a surface exposed to the outside and having a second polarity; a current collector plate welded to at least partially overlap the region and electrically connected to either the battery housing or the terminal; Including, When the total number of winding turns of the electrode including the uncoated portion is denoted by n i , the winding turn index k at the kth winding turn position is divided by the total number of winding turns n i to define the relative radial position R i,k for the winding turn index k. The ratio of the length of the radial section of R i,k which satisfies the condition that the number of overlapping layers of the uncoated portion is 10 or more is at least 25% with respect to the radius of the electrode assembly, When i is 1, it means that it is a factor related to the first electrode, when i is 2, it means that it is a factor related to the second electrode, when i is 1, n 1 means the total number of winding turns of the first electrode, when i is 2, n 2 means the total number of winding turns of the second electrode, k is a natural number from 1 to n, The number of overlapping layers of the uncoated portion is defined as the number of uncoated portions intersecting an imaginary line parallel to an axial direction of the electrode assembly at one point on the bent surface.

38. 38. The battery of claim 37, wherein said area overlaps with the welded area of ​​said current collector plate by 50% or more.

39. A battery pack comprising the battery of claim 37 or 38.

40. 40. A motor vehicle comprising the battery pack of claim 39.

Images