Electrode assemblies, batteries, battery packs containing them, and automobiles

Abstract

The present invention discloses an electrode assembly, a battery, a battery pack including the same, and an automobile. The electrode assembly is an electrode assembly in which a core and an outer circumferential surface are defined by winding a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode around a winding shaft, the first electrode includes a first active material portion coated with an active material layer along the winding direction, and a first uncoated portion that is not coated with the active material layer and is exposed to the outside of the separator, the first uncoated portion includes a plurality of segments that can be independently bent, the plurality of segments are defined as electrode tabs when folded along the radial direction of the electrode assembly, and at least a portion of the first uncoated portion in which the plurality of segments are provided includes a cutout portion extending along one direction parallel to the winding direction.

Description

[Technical Field]

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

[0002] This application claims priority based on Korean Patent Application No. 10-2022-0088962, filed on 19 July 2022, and all contents disclosed in the specification and drawings of said application are incorporated herein by reference. [Background technology]

[0003] Rechargeable batteries, which offer high applicability across different product groups and possess electrical characteristics such as high energy density, are commonly used not only in portable devices but also in electric vehicles (EVs) and hybrid electric vehicles (HEVs) powered by electric drive sources.

[0004] Such secondary batteries are attracting attention not only for their primary benefit of dramatically reducing the use of fossil fuels, but also because they are environmentally friendly in that they produce no by-products from energy use, making them a promising new energy source for improving energy efficiency.

[0005] Currently, rechargeable 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 a single rechargeable battery, i.e., a single battery, is approximately 2.5V to 4.5V. Therefore, when a higher output voltage is required, multiple batteries are connected in series to form a battery pack. Alternatively, multiple batteries may be connected in parallel to form a battery pack, depending on the required charge and discharge capacity. Thus, the number of batteries included in a battery pack and the electrical connection configuration can be set in various ways depending on the required output voltage and / or charge and discharge capacity.

[0006] On the other hand, known types of rechargeable batteries include cylindrical, prismatic, and pouch-type batteries. In the case of a cylindrical battery, an insulating separator membrane is interposed between the positive and negative electrodes, and this is wound up to form a jelly-roll type electrode assembly, which is then inserted into the battery housing to constitute the battery. The battery housing is called a battery can in this industry. Strip-shaped electrode tabs are connected to the blank portions of the positive and negative electrodes, and these electrode tabs electrically connect the electrode assembly to the electrode terminals exposed on the outside. For reference, the positive electrode terminal is the cap of the sealing body that seals the opening of the battery housing, and the negative electrode terminal is the battery housing. However, with conventional cylindrical batteries having such a structure, current is concentrated in the strip-shaped electrode tabs connected to the blank portion of the positive electrode and / or the blank portion of the negative electrode, resulting in high resistance, high heat generation, and poor current collection efficiency.

[0007] In small cylindrical batteries with form factors such as 1865 (diameter: 18mm, height: 65mm) and 2170 (diameter: 21mm, height: 70mm), resistance and heat generation are not much of a problem. However, when increasing the form factor of cylindrical batteries for application in electric vehicles, a problem can arise where the cylindrical battery catches fire during the rapid charging process due to the large amount of heat generated around the electrode tabs.

[0008] To solve these problems, a cylindrical battery (a so-called tab-less cylindrical battery) has been proposed in which a blank positive electrode section and a blank negative electrode section are located at the upper and lower ends of a jelly roll-type electrode assembly, respectively, and a current collector is welded to these blank sections to improve current collection efficiency.

[0009] Figures 1 to 3 illustrate the manufacturing process of a tablet cylindrical battery. Figure 1 shows the structure of the electrodes, Figure 2 shows the electrode winding process, and Figure 3 shows the process of welding the current collector to the bent surface area of ​​the plain section.

[0010] Referring to Figures 1 to 3, the positive electrode 10 and the negative electrode 11 have a structure in which a sheet-like current collector 20 is coated with an active material layer 21, and include a plain section 22 on one of the longer sides along the winding direction (X-axis). The longer side refers to the side that is parallel to the X-axis direction and has a relatively longer length.

[0011] Electrode assembly A is manufactured by sequentially stacking the positive electrode 10 and the negative electrode 11 together with two separation films 12, as shown in Figure 2, and then winding them in one direction (the X-axis direction). At this time, the plain portion of the positive electrode 10 and the plain portion of the negative electrode 11 are positioned in opposite directions.

[0012] After the winding process, the plain portion 10a of the positive electrode 10 and the plain portion 11a of the negative electrode 11 are bent towards the core. Then, the current collectors 30 and 31 are welded to the plain portions 10a and 11a, respectively, to join them.

[0013] The blank positive electrode section 10a and the blank negative electrode section 11a are not connected to separate electrode tabs, and the current collectors 30 and 31 are connected to external electrode terminals. As a result, the 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 battery's resistance. This is because resistance is inversely proportional to the cross-sectional area of ​​the path through which the current flows.

[0014] In a tablet cylindrical battery, in order to improve the welding characteristics between the plain sections 10a and 11a and the current collectors 30 and 31, strong pressure must be applied to the welding area of ​​the plain sections 10a and 11a to bend them as flat as possible.

[0015] However, when the welded areas of the plain sections 10a and 11a are bent, the patterns of the plain sections 10a and 11a may be irregularly distorted and deformed. In this case, the deformed parts may come into contact with electrodes of opposite polarity, causing an internal short circuit, or it may induce fine cracks in the plain sections 10a and 11a. Also, the plain section 32 adjacent to the core of electrode assembly A may be bent, blocking all or a portion of the cavity 33 in the core of electrode assembly A. In this case, problems arise in the electrolyte injection process. That is, the cavity 33 in the core of electrode assembly A is used as a passage for electrolyte injection. However, if this passage is blocked, it becomes difficult to inject the electrolyte. In addition, when the electrolyte injector is inserted into the cavity 33, it may interfere with the plain section 32 near the core, potentially causing the plain section 32 to tear.

[0016] Furthermore, the bent portions of the plain sections 10a and 11a to which the current collectors 30 and 31 are welded overlap multiple times, and there should be no empty spaces (gaps). This ensures sufficient welding strength and prevents problems such as the laser penetrating the inside of the electrode assembly A and melting the separation membrane or active material when using advanced technologies such as laser welding.

[0017] Conventional tablet cylindrical batteries have a blank positive electrode area 10a formed on the upper side of the electrode assembly A. Therefore, when the outer peripheral surface of the upper end of the battery housing is pushed inward to form the beading area, the peripheral region 34 of the upper end of the electrode assembly A is subjected to pressure from the battery housing. Such pressure can partially deform the electrode assembly A, and at this time, the separator membrane 12 may rupture, potentially causing an internal short circuit. If a short circuit occurs inside the battery, it may lead to overheating or explosion of the battery.

[0018] Furthermore, if the cylindrical battery is subjected to vibration or if the electrode assembly A expands due to an increase in the number of charge-discharge cycles, stress concentrates at the welded areas of the current collectors 30 and 31. Stress exceeding the critical value induces cracks in the blank portions 10a and 11a of the electrodes and the active material layer in their vicinity. If cracks occur in the active material layer, active material debris may detach from the electrodes, causing an internal short circuit. This is because fine active material debris can penetrate the separation membrane, bringing the positive and negative electrodes into contact in localized areas.

[0019] Short circuits occurring inside cylindrical batteries can lead to serious accidents, such as battery explosions. Therefore, there is an urgent need for a solution that can prevent internal short circuits by relieving the stress generated at the welded joints of the current collectors 30 and 31. [Overview of the Initiative] [Problems that the invention aims to solve]

[0020] The present invention was conceived against the background of the prior art described above, and one objective is to provide an electrode assembly having an improved plain section structure that can alleviate the stress applied to the plain section when the plain section exposed at both ends of the electrode assembly is bent.

[0021] Another objective of the present invention is to provide an electrode assembly having a structure that can prevent damage to the active material layer when stress exceeding a critical value is concentrated in the welded region of the current collector, by releasing the stress while the plain area near the welded region fractures.

[0022] Furthermore, another objective of the present invention is to provide an electrode assembly in which the electrolyte injection passage is not blocked even when the plain portion is bent.

[0023] Furthermore, another object of the present invention is to provide an electrode assembly that includes a structure capable of preventing the upper peripheral edge of the electrode assembly from coming into contact with the inner surface of the battery housing when the upper end of the battery housing is beaded.

[0024] Furthermore, the present invention aims to provide an electrode assembly in which the physical properties of the welding area are improved by applying a segmentation structure to the plain portion of the electrode and optimizing the dimensions (width, height, and spacing pitch) of the segmentation segments to sufficiently increase the number of stacked segmentation segments in the area used as the welding target area.

[0025] Furthermore, the present invention aims to provide an electrode assembly with improved energy density and reduced resistance by applying a structure in which a current collector is welded over a wide area to a bent surface region formed by bending a segment.

[0026] Furthermore, the present invention aims to provide a battery including terminals and current collectors with an improved design that allows for electrical wiring to be performed on top.

[0027] Furthermore, the present invention aims to provide a battery including an electrode assembly with an improved structure, a battery pack including the battery, and an automobile including the battery pack.

[0028] The technical problems that this invention aims to solve are not limited to those described above, and other problems will be clearly understood by an ordinary person from the following description of the invention. [Means for solving the problem]

[0029] To achieve the above objectives, an electrode assembly according to one aspect of the present invention is an electrode assembly in which a core and an outer surface are defined by winding a first electrode, a second electrode, and a separation membrane interposed between the first electrode and the second electrode around a winding shaft, wherein the first electrode comprises a first active material portion coated with an active material layer along the winding direction and a first plain portion not coated with an active material layer, the first plain portion being exposed to the outside of the separation membrane, the first plain portion comprising a plurality of independently bendable segments, the plurality of segments being defined as electrode tabs when bent along the radial direction of the electrode assembly, and at least a portion of the first plain portion comprising the plurality of segments comprising a cut-out portion extending along one direction parallel to the winding direction.

[0030] Each of the aforementioned subsections may have the form of a geometric figure formed by connecting at least one straight line, at least one curve, or a combination thereof.

[0031] A cutting groove may be interposed between adjacent segments along the winding direction. The cutting portion may be provided in the first blank region between the bottom of the cutting groove and the first active material portion.

[0032] The cut portion can be formed continuously along one direction parallel to the winding direction of the electrode assembly in the region of the first blank portion where the plurality of sub-sections are provided.

[0033] The cut portion may be formed discontinuously along one direction parallel to the winding direction of the electrode assembly in the region of the first blank portion where the plurality of sub-sections are provided.

[0034] The cut portion includes a plurality of sub-cut portions formed discontinuously along one direction parallel to the winding direction of the electrode assembly, and the first blank portion may include sections in which the length of the sub-cut portions gradually increases or decreases along the winding direction of the electrode assembly.

[0035] The cut portion includes a plurality of sub-cut portions formed discontinuously along one direction parallel to the winding direction of the electrode assembly, and the first blank portion may include a section in which the separation distance between adjacent sub-cut portions gradually increases or decreases along the winding direction of the electrode assembly.

[0036] The cut portion includes a plurality of sub-cut portions formed discontinuously along one direction parallel to the winding direction of the electrode assembly, and the plurality of sub-cut portions may have substantially the same height in the winding axis direction.

[0037] The cut portion includes a plurality of sub-cut portions formed discontinuously along one direction parallel to the winding direction of the electrode assembly, and the first blank portion may include regions in which the heights of the sub-cut portions in the winding axis direction are different.

[0038] The cut portion includes a plurality of sub-cut portions formed discontinuously along one direction parallel to the winding direction of the electrode assembly, and the first blank portion may include a section along the winding direction of the electrode assembly in which the distance between the cutting groove and the sub-cut portions gradually increases or decreases.

[0039] Preferably, the distance between the cut portion and the bottom of the cutting groove may be 0.1 mm to 1.9 mm.

[0040] The cut portion may include an arrangement of multiple punch holes along the winding direction of the electrode assembly.

[0041] The shape of the punched hole may be circular, square, rhombus, triangular, or elliptical.

[0042] The cut portion may include an arrangement of multiple grooves along the winding direction of the electrode assembly.

[0043] The shape of the groove may be circular, square, rhombic, triangular, or elliptical.

[0044] An insulating coating layer may be formed at the boundary between the plain area in the section where the bottom of the cutting groove and the first active material are separated, and the first active material. Furthermore, the distance from the bottom of the cutting groove to the cut portion may be shorter than the distance from the cut portion to the insulating coating layer.

[0045] An electrode assembly according to one aspect of the present invention may further include a current collector welded to a bent surface region formed by bending the plurality of segmental sections along the radial direction of the electrode assembly, wherein at least a portion of the cut-out portion may be provided to overlap with the lower region of the segmental sections welded to the current collector.

[0046] The cut portion does not need to intersect with a virtual line passing through the center of the upper edge and the center of the lower edge of the segment welded to the current collector.

[0047] In an electrode assembly according to one aspect of the present invention, the second electrode includes a second active material portion coated with an active material layer along the winding direction, and a second plain portion not coated with an active material layer, the second plain portion includes a plurality of independently bendable segments, the plurality of segments defined as electrode tabs when bent along the radial direction of the electrode assembly, and at least a portion of the second plain portion comprising the plurality of segments may include a cut-out portion extending along one direction parallel to the winding direction.

[0048] An electrode assembly according to one aspect of the present invention further includes a second current collector welded to a bent surface region formed by bending a plurality of segmental segments of the second blank portion, wherein the cut portion formed in the second blank portion may be formed between the segmental segments welded to the second current collector and the second active material portion.

[0049] The cut portion formed in the second blank portion does not need to intersect with the imaginary line passing through the center of the upper edge and the center of the lower edge of the segment welded to the second current collector.

[0050] To achieve the above objectives, a battery according to another aspect of the present invention is an electrode assembly in which a core and an outer surface are defined by winding a first electrode, a second electrode, and a separator membrane interposed between the first electrode and the second electrode around a winding shaft, wherein the first electrode includes a first active material portion coated with an active material layer along the winding direction, and a first plain portion not coated with an active material layer, and includes a first plain portion exposed to the outside of the separator membrane, the first plain portion includes a plurality of independently bendable segments, and the plurality of segments are bent along the radial direction of the electrode assembly to form an electrode tab and A battery housing comprising an electrode assembly, defined as such, wherein at least a portion of the first blank portion having the plurality of segmented segments includes a segment extending in one direction parallel to the winding direction; a battery housing having an open end and a bottom facing the open end, the space between the open end and the bottom housing the electrode assembly, and electrically connected to one of the first electrode and the second electrode to have a first polarity; a seal that seals the open end of the battery housing; and a terminal electrically connected to the other of the first electrode and the second electrode, the terminal having a second polarity with its surface exposed to the outside.

[0051] The sealing body includes a cap that seals the open end of the battery housing, a gasket interposed between the periphery of the cap and the open end of the battery housing, and a crimping portion that extends inward into the battery housing and is bent to wrap around and secure the periphery of the cap together with the gasket, wherein the terminal having the second polarity may be the cap.

[0052] A battery according to one aspect of the present invention further includes a first current collector welded to a bent surface region formed by bending the plurality of segmental segments of the first blank portion along the radial direction of the electrode assembly, wherein the cutouts formed in the first blank portion may be formed between the segmental segments welded to the first current collector and the first active material portion.

[0053] The cut portion does not need to intersect with a virtual line passing through the center of the upper edge and the center of the lower edge of the segment welded to the first current collector.

[0054] The terminal may be a rivet terminal having the second polarity, electrically connected to the first current collector, and insulatedly mounted in a through hole formed in the bottom of the battery housing.

[0055] A battery according to one aspect of the present invention may further include an insulator interposed between the inner surface of the bottom of the battery housing and the upper surface of the first current collector to electrically insulate the inner surface of the bottom of the battery housing from the first current collector.

[0056] In a battery according to one aspect of the present invention, the second electrode includes a second active material portion coated with an active material layer along the winding direction, and a second plain portion not coated with an active material layer, the second electrode has the first polarity, the second plain portion includes a plurality of independently bendable segments, the plurality of segments are defined as electrode tabs when bent along the radial direction of the electrode assembly, and at least a portion of the second plain portion having the plurality of segments may include a cut-out portion extending along one direction parallel to the winding direction.

[0057] A battery according to one aspect of the present invention further includes a second current collector welded to a bent surface region formed by bending a plurality of segmental segments of the second blank portion, wherein the cutouts formed in the second blank portion may be provided between the segmental segments welded to the second current collector and the second active material portion.

[0058] The cut portion formed in the second blank portion does not need to intersect with the imaginary line passing through the center of the upper edge and the center of the lower edge of the segment welded to the second current collector.

[0059] The battery housing includes a beading portion that is pushed inward from the inner wall adjacent to the open end, and at least a portion of the periphery of the second current collector can be electrically connected to the beading portion.

[0060] A battery according to one aspect of the present invention includes a non-polarized cap whose periphery is supported by the beading portion, a gasket interposed between the periphery of the cap and the open end of the battery housing, and a crimping portion that extends inward from the open end of the battery housing, is bent, and wraps around and secures the periphery of the cap together with the gasket, wherein at least a portion of the periphery of the second current collector can be interposed and secured between the beading portion and the gasket by the crimping portion.

[0061] At least a portion of the periphery of the second current collector can be welded to the beading portion.

[0062] The technical problem of the present invention is solved by a battery pack containing multiple of the above-mentioned batteries.

[0063] Preferably, the battery may have a height-to-diameter ratio greater than 0.4.

[0064] Preferably, the form factor of the battery may be 46110, 4875, 48110, 4880, or 4680.

[0065] Preferably, the resistance of the battery may be 4 mΩ or less.

[0066] In one embodiment, the battery pack may be arranged in a predetermined number of rows, with the electrode terminals of each battery and the outer surface of the bottom of the battery housing facing upward.

[0067] In other embodiments, the battery pack may include multiple busbars connecting multiple batteries in series and parallel.

[0068] Preferably, the multiple busbars are positioned on top of the multiple batteries, and each busbar may include a body portion extending between the electrode terminals of adjacent batteries, a plurality of first busbar terminals extending to one side of the body portion and electrically coupled to the electrode terminals of the battery located on that side, and a plurality of second busbar terminals extending to the other side of the body portion and electrically coupled to the outer surface of the bottom of the battery housing of the battery located on that side.

[0069] The technical challenges of the present invention can also be achieved by an automobile including the battery pack described above. [Effects of the Invention]

[0070] According to one aspect of the present invention, the internal resistance of the battery can be reduced and the energy density increased by using the plain portions protruding from the upper and lower sides of the electrode assembly as electrode tabs.

[0071] Furthermore, according to one aspect of the present invention, by improving the structure of the plain portion of the electrode assembly, interference between the electrode assembly and the inner circumferential surface of the battery housing is prevented during the process of forming the beading portion of the battery housing, thereby preventing internal short circuits in the cylindrical battery due to partial deformation of the electrode assembly.

[0072] Furthermore, according to one aspect of the present invention, by improving the structure of the plain portion of the electrode assembly, it is possible to prevent the plain portion from tearing when bent, and to sufficiently increase the number of overlapping layers of the plain portion to improve the welding strength of the current collector.

[0073] Furthermore, according to one aspect of the present invention, by applying a segmentation structure to the plain portion of the electrode and optimizing the dimensions of the segmentation segments (width, height, and spacing pitch) to sufficiently increase the number of stacked segmentation segments in the area used as the welding target area, the physical properties of the area to which the current collector is welded can be improved.

[0074] Furthermore, according to one aspect of the present invention, when stress exceeding a critical value is concentrated in the electrode assembly where the current collector is welded, the plain area (or segment) in the welded area and / or its vicinity breaks to relieve the stress, thereby providing an electrode assembly with a structure that can prevent damage to the active material layer.

[0075] Furthermore, according to one aspect of the present invention, by applying a structure in which a current collector is welded over a wide area to a bent surface region formed by bending a segment, it is possible to provide an electrode assembly with improved energy density and reduced resistance.

[0076] Furthermore, according to one aspect of the present invention, a cylindrical battery with an improved design that allows electrical wiring to be performed on the top can be provided.

[0077] Furthermore, according to one aspect of the present invention, by improving the structure of the plain portion adjacent to the core of the electrode assembly, it is possible to prevent the cavity in the core of the electrode assembly from becoming blocked when the plain portion is bent, thereby facilitating the electrolyte injection process and the welding process between the battery housing (or terminals) and the current collector.

[0078] Furthermore, according to one aspect of the present invention, it is possible to provide a cylindrical battery having a structure with low internal resistance, prevention of internal short circuits, and improved welding strength between the current collector and the blank portion, a battery pack including the cylindrical battery, and an automobile.

[0079] In particular, the present invention can provide a cylindrical battery having a height-to-diameter ratio of 0.4 or more and a resistance of 4 mΩ or less, a battery pack including the cylindrical battery, and an automobile.

[0080] The present invention also provides a variety of other effects, which will be described later with reference to embodiments. However, effects that can be easily inferred by an ordinary person will not be described.

[0081] The following drawings accompanying this specification illustrate preferred embodiments of the invention and, together with the detailed description of the invention, are intended to further illustrate the technical idea of ​​the invention; therefore, the invention shall not be construed as being limited solely to what is shown in the drawings. [Brief explanation of the drawing]

[0082] [Figure 1] This is a plan view showing the structure of electrodes used in the manufacture of conventional tablet cylindrical batteries. [Figure 2] This diagram shows the electrode winding process for a conventional cylindrical tablet battery. [Figure 3] This diagram illustrates the process of welding a current collector to the bent surface area of ​​the plain section in a conventional tabletless cylindrical battery. [Figure 4] This is a plan view showing the structure of an electrode according to the first embodiment of the present invention. [Figure 5] This is a plan view showing the structure of an electrode according to a second embodiment of the present invention. [Figure 6] This is a plan view showing the structure of an electrode according to a third embodiment of the present invention. [Figure 7a] This is a plan view showing the structure of an electrode according to a fourth embodiment of the present invention. [Figure 7b] This figure shows the definitions of the width, height, and spacing pitch of the section according to an embodiment of the present invention. [Figure 7c] This figure shows, with respect to the center of the core of the electrode assembly, the arc formed by the lower end of the segment that defines the width of the segment when the electrode is wound according to an embodiment of the present invention. [Figure 7d] This figure schematically shows the relationship between the heights h1, h2, h3, h4 of the segmentation section, the core radius rc, and the radii r1, r2, r3, r4 of the winding turns where the segmentation section begins to appear, according to an embodiment of the present invention. [Figure 7e] This is a conceptual diagram for determining the maximum value hmax of the segmental intercept height H in the segmental intercept height variable interval. [Figure 7f] This is a schematic diagram illustrating the formula for determining the lower interior angle θ of the segment. [Figure 7g] This is a plan view showing the deformed structure of an electrode according to the fourth embodiment of the present invention. [Figure 7h] This is a top view showing independent regions where multiple segments can be located when an electrode according to a modified form of the present invention is wound up as an electrode assembly. [Figure 7i] This is a plan view showing a first example in which a cut-out portion is formed in the plain portion of an electrode according to the fourth embodiment of the present invention. [Figure 7j] This is a plan view showing a second example in which a cut-out portion is formed in the plain portion of the electrode according to the fourth embodiment of the present invention. [Figure 7k] This is a plan view showing a third example in which a cut-out portion is formed in the plain portion of the electrode according to the fourth embodiment of the present invention. [Figure 7l] This is a plan view showing a fourth example in which a cut-out portion is formed in the plain portion of the electrode according to the fourth embodiment of the present invention. [Figure 7m] This is a plan view showing a fifth example in which a cut-out portion is formed in the plain portion of the electrode according to the fourth embodiment of the present invention. [Figure 7n] This is a plan view showing a sixth example in which a cut-out portion is formed in the plain portion of the electrode according to the fourth embodiment of the present invention. [Figure 8a] This is a plan view showing the structure of an electrode according to a fifth embodiment of the present invention. [Figure 8b] This figure shows the definitions of the width, height, and spacing pitch of the section according to another embodiment of the present invention. [Figure 8c] This is a plan view showing the deformed structure of an electrode according to the fifth embodiment of the present invention. [Figure 9] This figure shows the segment structure in various modified forms according to the present invention. [Figure 10a] This is a schematic diagram showing a cross-section of a bent surface region formed as the section is folded toward the core side of the electrode assembly. [Figure 10b] This is a schematic upper perspective view showing an electrode assembly with a bent surface region formed thereon. [Figure 10c]This graph shows the results of counting the number of stacked segments along the radial direction in the bent surface region of the positive electrode formed on the upper part of the electrode assemblies according to Examples 1-1 to 1-7 and the comparative example. [Figure 10d] This graph shows the results of counting the number of stacked segments measured along the radial direction in the bent surface region of the positive electrode formed on the upper part of the electrode assemblies according to Examples 2-1 to 2-5, Examples 3-1 to 3-4, Examples 4-1 to 4-3, Examples 5-1 and 5-2. [Figure 10e] This graph shows the results of counting the number of stacked segments measured along the radial direction in the bent surface region of the positive electrode formed on the upper part of the electrode assembly according to Examples 6-1 to 6-6 and Examples 7-1 to 7-6. [Figure 10f] This is a top view of an electrode assembly according to an embodiment of the present invention, showing a uniform layer number section b1 and a decreasing layer number section b2 in the folded surface region of a segment. [Figure 11] This is a cross-sectional view of a jelly roll-type electrode assembly, in which the electrodes of the first embodiment are applied to the first electrode (positive electrode) and the second electrode (negative electrode), cut along the Y-axis direction (winding axis direction). [Figure 12] This is a cross-sectional view of a jelly roll-type electrode assembly, in which the electrodes of the second embodiment are applied to the first electrode (positive electrode) and the second electrode (negative electrode), cut along the Y-axis direction (winding axis direction). [Figure 13] This is a cross-sectional view of a jelly roll-type electrode assembly, cut along the Y-axis direction (winding axis direction), in which one of the electrodes from the third to fifth embodiments (modified forms thereof) is applied as the first electrode (positive electrode) and the second electrode (negative electrode). [Figure 14] This is a cross-sectional view of an electrode assembly according to yet another embodiment of the present invention, cut along the Y-axis direction (winding axis direction). [Figure 15] This is a cross-sectional view of an electrode assembly according to yet another embodiment of the present invention, cut along the Y-axis direction (winding axis direction). [Figure 16] This is a cross-sectional view of an electrode assembly according to yet another embodiment of the present invention, cut along the Y-axis direction (winding axis direction). [Figure 17]This is a cross-sectional view of a cylindrical battery according to one embodiment of the present invention, cut along the Y-axis. [Figure 18] This is a cross-sectional view of a cylindrical battery according to another embodiment of the present invention, cut along the Y-axis. [Figure 19] This is a cross-sectional view of a cylindrical battery according to yet another embodiment of the present invention, cut along the Y-axis. [Figure 20] This is a cross-sectional view of a cylindrical battery according to yet another embodiment of the present invention, cut along the Y-axis. [Figure 21] This is a cross-sectional view of a cylindrical battery according to yet another embodiment of the present invention, cut along the Y-axis. [Figure 22] This is a cross-sectional view of a cylindrical battery according to yet another embodiment of the present invention, cut along the Y-axis. [Figure 23] This is a cross-sectional view of a cylindrical battery according to yet another embodiment of the present invention, cut along the Y-axis. [Figure 24] This is a cross-sectional view of a cylindrical battery according to yet another embodiment of the present invention, cut along the Y-axis. [Figure 25] This is a cross-sectional view of a cylindrical battery according to yet another embodiment of the present invention, cut along the Y-axis. [Figure 26] This is a top view showing the structure of the first current collector according to an embodiment of the present invention. [Figure 27] This is a top view showing the structure of a second current collector according to an embodiment of the present invention. [Figure 28] This is a top view showing multiple cylindrical batteries electrically connected. [Figure 29] This is a magnified view of a portion of Figure 28. [Figure 30] This diagram schematically shows the configuration of a battery pack according to one embodiment of the present invention. [Figure 31] This diagram schematically shows an automobile including a battery pack according to one embodiment of the present invention. [Modes for carrying out the invention]

[0083] Preferred embodiments of the present invention will now be described in detail with reference to the attached drawings. Prior to this, terms and words used herein and in the claims shall not be interpreted in their usual and dictionary sense, but rather in a sense and concept that corresponds to the technical idea of ​​the present invention, in accordance with the principle that the inventor himself may appropriately define the concept of terms in order to best describe the invention.

[0084] Therefore, the embodiments described herein and the configurations shown in the drawings represent only one of the most preferred embodiments of the present invention and do not represent the entire technical concept of the invention. It should be understood that there are various equivalents and modifications that can be substituted for these at the time of filing this application.

[0085] Furthermore, to aid in understanding the invention, the accompanying drawings are not shown to actual scale, and the dimensions of some components may be exaggerated. Also, the same component in different embodiments may be assigned the same reference numeral.

[0086] The expression that two comparison objects are identical means that they are "substantially identical." Therefore, "substantially identical" may include deviations that are considered low in this industry, for example, deviations of 5% or less. Furthermore, when a parameter is said to be uniform in a given domain, it means that it is uniform in that domain from an average perspective.

[0087] Furthermore, while terms like "first," "second," etc., are used to indicate various components, these terms are not intended to limit the components. These terms are simply used to distinguish one component from others, and unless otherwise specified, the first component can also be the second component.

[0088] Throughout the specification, unless otherwise specified, each component may be singular or plural.

[0089] To say that any component is placed "above (or below)" or "above (or below)" a component means not only that the component is placed in contact with the upper (or lower) surface of the component, but also that other components may be interposed between the component and any component placed above (or below) it.

[0090] Furthermore, when one component is described as being "connected," "joined," or "linked" to another component, this includes not only cases where the components are directly connected to or linked to each other, but also cases where other components are "interposed" between each component, or where each component is "connected," "joined," or "linked" through other components.

[0091] Throughout this specification, "A and / or B" means A, B, or A and B unless otherwise specified, and "C-D" means C to D unless otherwise specified.

[0092] In this specification, for the sake of explanation, 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 periphery direction (X-axis). The direction approaching or moving away from the winding shaft is referred to as the radial direction. Of these, the direction approaching the winding shaft is referred to as the centripetal direction, and the direction moving away from the winding shaft is referred to as the centrifugal direction.

[0093] First, an electrode assembly according to one embodiment of the present invention will be described. The electrode assembly may be a jelly roll type electrode assembly having a structure in which a sheet-like first electrode, a second electrode, and a separation membrane interposed between the first electrode and the second electrode are wound in one direction. However, the present invention is not limited by the type of electrode assembly.

[0094] Preferably, at least one of the first electrode and the second electrode includes a plain portion at the long edge in the winding direction where the active material is not coated. At least a portion of the plain portion is used as an electrode tab. The plain portion includes a core-side plain portion adjacent to the core of the electrode assembly, an outer-circumferential plain portion adjacent to the outer surface of the electrode assembly, and an intermediate plain portion interposed between the core-side plain portion and the outer-circumferential plain portion.

[0095] Preferably, at least one of the plain core portion and the plain outer periphery portion is relatively lower in height than the intermediate plain portion.

[0096] Figure 4 is a plan view showing the structure of the electrode 40 according to the first embodiment of the present invention.

[0097] Referring to Figure 4, the electrode 40 of the first embodiment includes a current collector 41 made of metal foil and an active material layer 42. The metal foil may be a conductive metal, such as aluminum or copper, and is appropriately selected according to the polarity of the electrode 40. The active material layer 42 is formed on at least one surface of the current collector 41. The active material layer 42 is formed along the winding direction (X-axis). The electrode 40 includes a plain portion 43 at the long side end in the winding direction (X-axis). The plain portion 43 is a part of the current collector 41 that is not coated with active material. The region of the current collector 41 on which the active material layer 42 is formed may be called the active material portion.

[0098] In electrode 40, the width of the active material portion in the short-side direction of the current collector 41 can be 50 mm to 120 mm, and the length of the active material portion in the long-side direction of the current collector 41 can be 3 m to 5 m. Therefore, the ratio of the short side to the long side of the active material portion can be 1.0% to 4.0%.

[0099] Preferably, in the electrode 40, the width of the active material portion in the short-side direction of the current collector 41 may be 60 mm to 70 mm, and the length of the active material portion in the long-side direction of the current collector 41 may be 3 m to 5 m. Therefore, the ratio of the short side to the long side of the active material portion may be 1.2% to 2.3%.

[0100] The ratio of the short side to the long side of the active material portion is significantly smaller than the 6%–11% ratio of the short side to the long side of the active material portion of the electrode used in cylindrical batteries with a 1865 or 2170 form factor.

[0101] Preferably, the current collector 41 has an elongation ratio of 1.5% to 3.0% and a tensile strength of 25 gf / mm². 2 ~35 kgf / mm 2 This is possible. The elongation and tensile strength can be measured according to the IPC-TM-650 measurement method. The electrode 40 is manufactured by forming an active material layer 42 on the current collector 41 and then crimping it. During crimping, the elongation differs between the plain area 43 and the active material layer 42. Therefore, swell occurs in the electrode 40 after crimping, and the swell worsens as the electrode 40 becomes longer.

[0102] Optimization of the elongation ratio and tensile strength of the current collector 41 reduces the camber length after crimping to less than 20 mm when the length of the electrode 40 is at the 4 m level. The camber length is the maximum deflection of the electrode 40 in the winding direction (X axis) when the undulating electrode 40 is unfolded. The maximum deflection can be measured at the outer end. Because the elongation ratio and tensile strength of the current collector 41 are optimized for the electrode 40, the camber length is short, preventing meandering defects during the notching of the plain section 43 and the winding process of the electrode 40.

[0103] The current collector 41 is more prone to breakage the smaller its elongation rate. If the elongation rate of the current collector 41 is less than 1.5%, the rolling processability of the current collector 41 decreases, and there is a risk of wire breakage in the current collector 41 when the electrode 40 coated with the active material layer 42 is crimped onto the current collector 41. On the other hand, if the elongation rate of the current collector 41 exceeds 3.0%, the active material portion of the electrode 40 is excessively stretched, and the camber length increases significantly. The tensile strength of the current collector 41 is 25 kgf / mm². 2 Less than or 35 kgf / mm 2 If it exceeds this value, the electrode processability of electrode 40 deteriorates.

[0104] The camber phenomenon is particularly problematic in positive electrode current collectors made of aluminum foil. This invention achieves an elongation ratio of 1.5% to 3.0% and a tensile strength of 25 kgf / mm². 2 ~35 kgf / mm 2 By using aluminum foil as a current collector, the camber phenomenon can be suppressed. It is preferable to form an active material layer on such a current collector and use it as a positive electrode.

[0105] Preferably, an insulating coating layer 44 may be formed at the boundary between the active material layer 42 and the blank portion 43. The insulating coating layer 44 is formed so that at least a portion of it overlaps the boundary between the active material layer 42 and the blank portion 43. The insulating coating layer 44 prevents short circuits between two electrodes of opposite polarity that are facing each other with a separator film in between. The insulating coating layer 44 may cover the boundary portion between the active material layer 42 and the blank portion 43 with a width of 0.3 mm to 5 mm. The width of the insulating coating layer 44 may vary along the winding direction of the electrode 40. The insulating coating layer 44 contains a polymer resin and may contain an inorganic filler such as Al2O3. The portion of the current collector 41 covered by the insulating coating layer 44 may be considered a blank portion because it is not a region coated with the active material layer.

[0106] The plain portion 43 includes a core-side plain portion B1 adjacent to the core side of the electrode assembly, an outer-circumferential plain portion B3 adjacent to the outer-circumferential side of the electrode assembly, and an intermediate plain portion B2 interposed between the core-side plain portion B1 and the outer-circumferential plain portion B3.

[0107] The plain core portion B1, the plain outer peripheral portion B3, and the plain intermediate portion B2 can be defined as the plain region adjacent to the core, the plain region adjacent to the outer peripheral, and the plain region excluding these areas, respectively, when the electrode 40 is wound up as a jelly roll-type electrode assembly.

[0108] Hereinafter, the plain core section B1, the plain outer perimeter section B3, and the plain intermediate section B2 will be referred to as the first section, the second section, and the third section, respectively.

[0109] For example, the first portion B1 may be a plain area of ​​the electrode region including the innermost winding turn, and the second portion may be a plain area of ​​the electrode region including the outermost winding turn. The winding turns can be counted relative to the core-side end of the electrode assembly.

[0110] As another example, the B1 / B2 boundary can be appropriately defined at a point where the height (or variation pattern) of the plain area substantially changes from the core side to the outer circumference of the electrode assembly, or at a predetermined percentage point relative to the radius of the electrode assembly (e.g., 5%, 10%, 15% of the radius).

[0111] The B2 / B3 boundary can be defined at the point where the height (or variation pattern) of the plain area substantially changes from the outer circumference of the electrode assembly toward the core, or at a predetermined percentage point relative to the radius of the electrode assembly (e.g., 85%, 90%, 95% of the radius). Once the B1 / B2 boundary and the B2 / B3 boundary are identified, the third part B2 can be automatically identified.

[0112] If only the B1 / B2 boundary is specified, the B2 / B3 boundary can be appropriately selected at a point near the outer circumference of the electrode assembly. For example, the second portion can be defined as the plain area of ​​the electrode region constituting the outermost winding turn. On the other hand, if only the B2 / B3 boundary is specified, the B1 / B2 boundary can be appropriately selected at a point near the core side of the electrode assembly. For example, the first portion can be defined as the plain area of ​​the electrode region constituting the innermost winding turn.

[0113] This does not rule out the possibility of other structures intervening between the first part B1 and the third part B2. Nor does it rule out the possibility of other structures intervening between the third part B2 and the second part B3.

[0114] In the first embodiment, the height of the plain section 43 is not constant and varies relative to the winding direction (X-axis). That is, the height of the second section B3 (length in the Y-axis direction) is 0 or greater and is relatively lower than the first section B1 and the third section B2. Here, the height of each section may be the average height or the maximum height, and so on. In the winding direction, the length of the third section B2 is even longer than the first section B1 and the second section B3.

[0115] Figure 5 is a plan view showing the structure of the electrode 45 according to a second embodiment of the present invention.

[0116] Referring to Figure 5, the electrode 45 of the second embodiment differs from that of the first embodiment only in that the height of the second portion B3 gradually decreases toward the outer circumference; the other configurations are substantially the same.

[0117] In one modified form, the second part B3 can be transformed into a stepped shape with a gradually decreasing height (see dotted line).

[0118] Figure 6 is a plan view showing the structure of the electrode 50 according to the third embodiment of the present invention.

[0119] Referring to Figure 6, in the third embodiment, the electrode 50 has a height of 0 or greater for the first portion B1 and the second portion B3, and is relatively lower than the third portion B2. Also, the heights of the first portion B1 and the second portion B3 may be the same or different.

[0120] Preferably, the height of the third portion B2 may be in a stepped shape, gradually increasing from the core side towards the outer periphery.

[0121] Patterns 1 to 7 divide the third section B2 around the position where the height of the plain section 43 changes. Preferably, the number of patterns, the height (length in the Y-axis direction), and the width (length in the X-axis direction) of each pattern are adjustable so as to maximize stress distribution during the bending process of the plain section 43. Stress distribution is intended to prevent the plain section 43 from tearing when it is bent towards the core side of the electrode assembly.

[0122] Width d of the first part B1 B1 When the pattern of the third part B2 is bent toward the core side, it is designed by applying the condition that the core of the electrode assembly is not blocked. The core means a cavity existing at the winding center of the electrode assembly.

[0123] As an example, the width d of the first part B1 B1 can increase in proportion to the bending length of Pattern 1. The bending length corresponds to the height of the pattern based on the bending point of the pattern.

[0124] Preferably, the width d of the first part B1 B1 can be set such that the radial width of the winding turn formed by the first part B1 is not less than the bending length of Pattern 1. In a modified example, the width d of the first part B1 B1 can be set such that the value obtained by subtracting the radial width of the winding turn formed by the first part B1 from the bending length of Pattern 1 is less than 0 or not more than 10% of the core radius.

[0125] B1 In a specific example, when the electrode 50 is used to manufacture an electrode assembly of a cylindrical battery with a form factor of 4680, the width d of the first part B1

[0126] In an example, the width of each pattern can be designed to constitute one or more winding turns of the electrode assembly.

[0127] In another example, the height of the third part B2 can be in a stepped shape that increases from the core side toward the outer peripheral side and then decreases.

[0128] In yet another example, the second part B3 can be deformed to have the same structure as that of the second embodiment.

[0129] ​In other examples, the pattern structure applied to the third part B2 can be extended to the second part B3 (see dotted line).

[0130] Figure 7a is a plan view showing the structure of the electrode 60 according to the fourth embodiment of the present invention.

[0131] Referring to Figure 7a, in the fourth embodiment, the electrode 60 has a height of 0 or greater in the winding axis (Y-axis) direction for the first portion B1 and the second portion B3, and is relatively lower than the third portion B2. Also, the height of the first portion B1 and the height of the second portion B3 in the winding axis (Y-axis) direction may be the same or different.

[0132] Preferably, the third portion B2 may include a plurality of subsections 61 in at least a portion of its length. The subsections 61 may have a height that increases gradually from the core side to the outer periphery side. The subsections 61 have a geometric shape in which the width decreases from the bottom to the top. Preferably, the geometric shape is trapezoidal. As will be described later, the geometric shape can be varied in many ways.

[0133] The section 61 may be notched with a laser. The section 61 may be formed by known metal foil cutting processes such as ultrasonic cutting or punching.

[0134] In the fourth embodiment, when bending the plain portion 43, it is preferable to provide a predetermined gap between the bottom of the cutting groove between the segment pieces 61 (G in Figure 7b) and the active material layer 42 in order to prevent damage to the active material layer 42 and / or the insulating coating layer 44. This is because stress is concentrated near the bottom of the cutting groove 63 when the plain portion 43 is bent. The gap may vary along the winding direction of the electrode 60. The gap is preferably 0.2 mm to 4 mm, more preferably 1.5 mm to 2.5 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 bottom of the cutting groove 63 due to stress generated when bending the plain portion 43. Furthermore, the gap can prevent damage to the active material layer 42 and / or the insulating coating layer 44 due to notches or tolerances during cutting of the segment pieces 61. In one direction parallel to the winding direction, the gap may be substantially the same or vary. In the latter case, the gap between multiple segments can vary individually, in groups, or in groups of two or more along one direction parallel to the winding direction. The bottom of the cutting groove 63 and the insulating coating layer 44 can be separated by 0.5 mm to 2.0 mm. In one direction parallel to the winding direction, the separation distance between the bottom of the cutting groove 63 and the insulating coating layer 44 may be approximately the same or vary. In the latter case, the separation distance between multiple segments can vary individually, in groups, or in groups of two or more along one direction parallel to the winding direction. When the electrode 60 is wound, the end of the insulating coating layer 44 in the direction of the winding axis (Y axis) can be located in the range of -2 mm to 2 mm along the winding axis direction with respect to the end of the separation membrane. The insulating coating layer 44 can prevent short circuits between two electrodes of opposite polarity facing each other with the separation membrane in between, and can support the bending point when the segment 61 is bent. To improve the short-circuit prevention effect between the two electrodes, the insulating coating layer 44 may be exposed to the outside of the separation film. Furthermore, to further maximize the short-circuit prevention effect between the two electrodes, the width of the insulating coating layer 44 may be increased so that the end of the insulating coating layer 44 in the direction of the winding axis (Y axis) is located above the bottom of the cutting groove 63.In one example, the end of the insulating coating layer 44 in the winding axis direction may be located within a range of -2 mm to +2 mm relative to the bottom of the cutting groove 63. The thickness of the insulating coating layer 44 may be thinner than that of the active material layer. In this case, a gap may exist between the surface of the insulating coating layer 44 and the separation film.

[0135] In one embodiment, the multiple subsections 61 may form multiple subsection groups from the core side to the outer circumference side. At least one of the width, height, and spacing pitch of subsections belonging to the same subsection group may be substantially the same. Preferably, the width, height, and spacing pitch of subsections belonging to the same subsection group may be the same.

[0136] Preferably, the width and height of sections belonging to the same section group may be substantially the same.

[0137] In other forms, the segments may be arranged in groups or in groups of two or more groups, with the spacing pitch gradually or stepwise increasing from the core side to the outer periphery side, or vice versa.

[0138] In yet another form, the segments may, in groups or in groups of two or more, have a separation pitch that gradually or stepwise increases from the core side to the outer periphery side, then gradually or stepwise decreases, or vice versa.

[0139] In yet another embodiment, the gap between the bottom of the cutting groove 63 and the insulating coating layer 44 or active material layer 42 may increase gradually or stepwise from the core side to the outer circumference, or vice versa.

[0140] In yet another embodiment, the gap between the bottom of the cutting groove 63 and the insulating coating layer 44 or active material layer 42 may increase or decrease gradually or stepwise from the core side to the outer circumference, or vice versa.

[0141] Figure 7b shows the definitions of the width D, height H, and separation pitch P of the trapezoidal segment 61.

[0142] Referring to Figure 7b, the width D, height H, and separation pitch P of the segment 61 are designed to prevent the plain section 43 from tearing near the bending point during bending and to ensure sufficient welding strength, while also preventing abnormal deformation of the plain section 43 by sufficiently increasing the number of overlapping layers of the plain section 43.

[0143] The folding of the segment 61 is performed along or above the line G passing through the bottom of the cutting groove 63. The cutting groove 63 allows for smooth and easy folding of the segment 61 in the radial direction of the electrode assembly.

[0144] The width D of the segment 61 is defined by the distance between two points where two straight lines extending from the side edges 63b of the segment 61 intersect with a straight line extending from the bottom 63a of the cutting groove 63. The height H of the segment 61 is defined by the shortest distance between the uppermost edge of the segment 61 and the straight line extending from the bottom 63a of the cutting groove 63. The spacing pitch P of the segment 61 is defined by the distance between two points where a straight line extending from the bottom 63a of the cutting groove 63 intersects with two straight lines extending from the two side edges 63b connected to the bottom 63a. When the side edges 63b and / or the bottom 63a are curves, the straight lines can be replaced by tangents extending from the intersection of the side edges 63b and the bottom 63a to the side edges 63b and / or the bottom 63a.

[0145] Preferably, the width D of the segment 61 is 1 mm or more. If D is less than 1 mm, when the segment 61 is bent toward the core, the segment 61 may not overlap to a sufficient extent to ensure sufficient welding strength, or a gap may be created.

[0146] Preferably, the width D of the segment 61 can be adaptively adjusted according to the radius of the winding turn in which the segment 61 is located, so that when the segment 61 is bent toward the core side of the electrode assembly, the segment 61 easily overlaps radially.

[0147] Figure 7c shows the lower end of the segment 61 (line segment D in Figure 7b) where the width D of the segment 61 is defined when the electrode 60 is wound according to an embodiment of the present invention. ab This diagram shows the arcs A1 and A2 formed by the electrode assembly, with respect to the center O of the core.

[0148] Referring to Figure 7c, the arc A1A2 has a length corresponding to the width D of the segment 61 and has an inscribed angle Φ with respect to the center of the core of the electrode assembly. The inscribed angle Φ can be defined as the angle between two line segments connecting the ends of the arc A1A2 and the center O of the core, on a plane perpendicular to the winding axis passing through the arc A1A2.

[0149] When the lengths of the arcs A1 and A2 of the segment 61 are the same, the inscribed angle Φ decreases as the radius r of the winding turn in which the segment 61 is located increases. Conversely, when the inscribed angle Φ of the segment 61 is the same, the lengths of the arcs A1 and A2 increase proportionally as the radius r of the winding turn in which the segment 61 is located increases.

[0150] The inscribed angle Φ affects the bending quality of the segment 61. In the drawing, solid arrows indicate the direction of the force applied to bend the segment 61, and dotted arrows indicate the direction in which the segment 61 is bent. The bending direction is toward the center O of the core.

[0151] The inscribed angle Φ of the segment 61 may be 45° or less, preferably 30° or less, depending on the radius r of the winding turn in which the segment 61 is located, in order to improve the uniformity of bending and prevent the occurrence of cracks.

[0152] In one embodiment, the inscribed angle Φ of the segmentation section 61 may gradually or stepwise increase or decrease along the radial direction of the electrode assembly within the above numerical range. In another embodiment, the inscribed angle Φ of the segmentation section 61 may gradually or stepwise increase and then gradually or stepwise decrease along the radial direction of the electrode assembly within the above numerical range, and vice versa is also possible. In yet another embodiment, the inscribed angle Φ of the segmentation section 61 may be substantially the same along the radial direction of the electrode assembly within the above numerical range.

[0153] Experiments have shown that when the inscribed angle Φ of the segment 61 exceeds 45°, the folding pattern of the segment 61 becomes uneven. The difference in force applied to the central and side portions of the segment 61 becomes large, resulting in uneven pressure on the segment 61 in the circumferential direction. Furthermore, if the pressing force is increased to ensure folding uniformity, cracks may occur in the plain area 43 near the cutting groove 63.

[0154] In one example, the inscribed angles Φ of the segmental sections 61 contained within the electrode 60 are substantially identical, and the width of the segmental section 61 may increase proportionally as the radius r of the winding turn in which the segmental section 61 is located increases. Substantially identical means either completely identical or with a deviation of less than 5%.

[0155] For example, if the radius of the electrode assembly is 22 mm, the radius of the core is 4 mm, and the segment 61 is positioned from a winding turn located at a radius of 7 mm, and the inscribed angle Φ of the segment 61 is constant at 28.6°, then the width D of the segment 61 can increase proportionally with respect to the radius r of the winding turn in which the segment 61 is located, as shown in Table 1 below. That is, the width of the segment 61 can increase by 0.5 mm at substantially the same rate for every 1 mm increase in the radius r of the winding turn.

[0156] [Table 1]

[0157] Preferably, the width D(r) of the segment 61 located in a winding turn with radius r relative to the center O of the electrode assembly core can be determined within a range that satisfies the following formula 1.

[0158] [Formula 1] 1≦D(r)≦(2×π×r / 360°)×45° Preferably, each of the multiple segment sections 61 may have a winding width D(r) that increases gradually or in steps as the radius r of the winding turn in which the segment section 61 is located increases, relative to the center of the core of the electrode assembly, or vice versa.

[0159] In other embodiments, each of the multiple subsections 61 may have a winding width D(r) that increases gradually or in steps in the winding direction, ranging from 1 mm to 11 mm, as the radius r of the winding turn in which the subsection 61 is located increases with respect to the center of the core of the electrode assembly, or vice versa.

[0160] In yet another embodiment, each of the multiple subsections 61 may have a winding width D(r) that gradually or stepwise increases and then gradually or stepwise decreases as the radius r of the winding turn in which the subsection 61 is located increases with respect to the center of the core of the electrode assembly, or vice versa.

[0161] In yet another embodiment, each of the multiple subsections 61 may have a winding width D(r) that gradually or stepwise increases and then gradually or stepwise decreases in the range of 1 mm to 11 mm as the radius r of the winding turn in which the subsection 61 is located increases with respect to the center of the electrode assembly core, or vice versa.

[0162] In other embodiments, the rate at which the width D(r) of the segment 61 changes as the radius r of the winding turn in which the segment 61 is located increases may be the same or different.

[0163] In other configurations, the rate at which the width D(r) of the segment 61 changes in the range of 1 mm to 11 mm as the radius r of the winding turn in which the segment 61 is located increases may be the same or different.

[0164] Referring further to Figure 7b, the height H of the segment 61 may be 2 mm or more. If D2 is less than 2 mm, when the segment 61 is bent toward the core, the segment 61 may not overlap to a sufficient extent to ensure sufficient welding strength, or a gap may be created.

[0165] The height H of the segment 61 can be determined by applying the condition that the segment 61 does not block the core when it is folded toward the core. Preferably, the height H of the segment 61 can be adjusted so that 90% or more of the core's diameter is open to the outside.

[0166] Preferably, the height H of the segment 61 can gradually increase from the core side to the outer circumference depending on the radius of the winding turn and the radius of the core in which the segment 61 is located.

[0167] In one example, the height H of the segment 61 increases from h1 to h as the radius of the winding turn increases. N As it increases stepwise over N steps, the k-th height h of the segment 61 k (k is a natural number from 1 to N), height h k The starting radius of the winding turn is r, which includes a segment 61 having a segment 61. k , the radius of the core is r c When this is the case, the heights h1 to h of the segment 61 should satisfy the following equation 2. N This may be decided.

[0168] [Formula 2] 2mm≦h k ≤r k -α×r c (Preferably, α is 0.90 to 1) Height h of segment 61 k If equation 2 is satisfied, then even if the segment 61 is bent toward the core, the core can be open to the outside by more than 90% of its diameter.

[0169] For example, if the overall winding turn radius of the electrode assembly is 22 mm, the height of the segment 61 starts at 3 mm, and for every 1 mm increase in the radius of the winding turn containing the segment 61, the height of the segment 61 increases sequentially to 3 mm, 4 mm, 5 mm, and 6 mm, and the height can be maintained substantially the same at 6 mm in the remaining winding turns. In other words, the radial width of the variable height section of the segment 61 within the radius of the overall winding turn is 3 mm, and the remaining radial section corresponds to the uniform height section.

[0170] In this case, the radius r of the core of the electrode assembly c The starting radii r1, r2, r3, and r3 of the winding turns, which include segment 61 having heights of 3 mm, 4 mm, 5 mm, and 6 mm respectively, are as shown in Table 2 below, when α is 1 and the equality condition is applied in the inequality on the right.

[0171] [Table 2]

[0172] When the segment 61 is positioned at the radial position shown in Table 2, the core is not blocked by the segment 61 even if it is bent towards the core. On the other hand, r1, r2, r3, and r3 shown in Table 2 can be shifted towards the core depending on the α value. In one example, when α is 0.90, r1, r2, r3, and r3 can be shifted towards the core by 10% of the core radius. In this case, when the segment 61 is bent towards the core, 10% of the core radius is blocked by the segment 61. r1, r2, r3, and r3 shown in Table 2 are limit values ​​for the starting position of the segment 61. Therefore, the position of the segment 61 can be shifted by a predetermined distance towards the outer circumference from the radius shown in Table 2.

[0173] Figure 7d shows the heights h1, h2, h3, h4 of the section 61 and the core radius r. c This diagram schematically shows the relationship between the radii r1, r2, r3, and r3 of the winding turn where the segment 61 begins to appear.

[0174] Referring to Table 2 and Figure 7d, for example, the radius r of core Cc When is 3m, the starting radii r1, r2, r3, and r3 of the winding turns containing subsections 61 with heights of 3mm(h1), 4mm(h2), 5mm(h3), and 6mm(h4) can be 6mm, 7mm, 8mm, and 9mm, respectively, and the height of the subsection 61 can be maintained at 6mm from radius 9mm to the last winding turn. Also, winding turns with radii smaller than 6mm(r1) do not need to contain subsections 61. In such an example, since the subsection 61 with a height of 3mm(h1) closest to the core C is located from a winding turn with a radius of 6mm, even if the subsection 61 is bent toward the core C, it only covers the radius section from 3mm to 6mm and does not substantially block the core C. Depending on the α value in Equation 2, the position of the subsection 61 is determined by the core radius r c It can be shifted to the core C side by up to 10%.

[0175] In other embodiments, the height of the segment 61 may increase by the same or different ratio as the starting radius r of the winding turn in which the segment 61 is located increases with respect to the center of the core of the electrode assembly.

[0176] Preferably, the height H of the segment 61 satisfies formula 2, and the maximum height of the segment 61 can be limited.

[0177] Figure 7e shows the maximum value h with respect to the height H of the subsection 61 in the height-variable interval of the subsection 61. max This is a conceptual diagram for determining the outcome.

[0178] Referring to Figure 7e, in the winding structure of the electrode assembly, electrode E1, which includes the segment 61, faces electrode E2 of opposite polarity in the radial direction, with a separation membrane S in between. Active material layers E are present on both sides of electrode E1. 1,active The electrode E2 is coated with an active material layer E on both sides. 2,active It is coated. For electrical insulation, the edges S of the separator film S end This is the end of electrode E2. 2,end From the insulation gap W gapIt may extend further outward by a length corresponding to that. Also, the end of electrode E1 does not extend further outward than the end of electrode E2 for electrical insulation. Therefore, there is an insulating gap W at the lower end of the plain section 43. gap A corresponding section must be secured. Also, when electrodes E1 and E2 and the separation membrane S are wound up, the end S of the separation membrane S end This causes meandering. Therefore, for the section 61 to be exposed to the outside of the separation membrane S, the section W corresponding to the minimum meandering margin of the separation membrane S must be exposed. margin,min The blank section 43 must be allocated to it. Also, in order to cut the segment 61, a minimum cutting scrap margin W must be placed at the end of the current collector foil. scrap,min A value must be assigned. Therefore, the maximum height h of the subsection 61 in the height-variable section of the subsection 61. max This can be determined by the following equation 3. In equation 3, W foil This corresponds to the width of the current collector foil before it is cut.

[0179] [Formula 3] h max =W foil -W scrap,min -W margin,min -W gap Preferably, the insulation gap W gap The insulation gap W can be 0.2 mm to 6 mm when the first electrode is the positive electrode. gap This can be 0.1 mm to 2 mm when the first electrode is the negative electrode.

[0180] Preferably, the minimum cutting scrap margin W scrap,min This can be 1.5mm to 8mm. Minimum cutting scrap margin W scrap,min This does not have to be assigned by the process of forming the segment 61. For example, the cutting groove 63 can be formed so that the upper edge of the segment 61 coincides with the upper edge of the current collector wheel. In this case, in equation 3, W scrap,min It can be 0.

[0181] Preferably, the minimum meandering margin W of the separation membrane. margin,min It can be 0-1 mm.

[0182] As an example, the minimum cutting scrap margin W scrap,min The minimum meandering margin W of the separation membrane S is 1.5 mm. margin,min This can be 0.5 mm. Under these conditions, the width W of the current collector wheel before forming the segment 61. foil The insulation gap is 8mm to 12mm, and W gap When the dimensions are 0.6 mm, 0.8 mm, and 1.0 mm, the maximum height h of the segment 61 can be calculated using formula 3. max The results of the calculation are shown in Table 3 below.

[0183] [Table 3]

[0184] Referring to Table 3, the maximum height h of the subsection 61 in the height-variable section of the subsection 61 max The distance can be set to 10 mm. Therefore, the height of the segment 61 in the height variable section of the segment 61 satisfies Equation 2 and can be increased stepwise or gradually along the radial direction of the electrode assembly in the 2 mm to 10 mm range. Referring further to Figure 7b, the separation pitch P of the segment 61 can be adjusted from 0.05 to 1.0 mm. If the separation pitch P is less than 0.05 mm, when the electrode 60 runs during the winding process, etc., stress may cause cracks in the plain section 43 near the bottom of the cutting groove 63. On the other hand, if the separation pitch P exceeds 1 mm, when the segment 61 is bent, the segment 61 may not overlap to a degree that allows sufficient welding strength to be ensured, or gaps may be created.

[0185] On the other hand, when the current collector 41 of the electrode 60 is made of aluminum, it is more preferable to set the separation pitch P to 0.5 mm or more. When the separation pitch P is 0.5 mm or more, even if the electrode 60 travels at a speed of 100 mm / sec or more under a tension of 300 gf or more in a winding process or the like, it is possible to prevent cracks from occurring at the lower part of the cutting groove 63.

[0186] According to the experimental results, when the current collector 41 of the electrode 60 is an aluminum foil with a thickness of 15 μm and the separation pitch P is 0.5 mm or more, no cracks occur at the lower part of the cutting groove 63 when the electrode 60 travels under the above running conditions.

[0187] As shown in FIG. 7b, a cutting groove 63 is interposed between two adjacent divided sections 61 in the winding direction (X-axis). The cutting groove 63 corresponds to the space generated while the plain part 43 is removed. Preferably, the corner portions at both ends of the bottom of the cutting groove 63 are round. That is, the cutting groove 63 includes a substantially flat bottom 63a and a round portion 63c. The round portion 63c connects the bottom 63a and the side 63b of the divided section 61. In a modified example, the bottom 63a of the cutting groove 63 may be replaced with an arc shape. In this case, the sides 63b of the divided section 61 can be smoothly connected by the arc shape of the bottom 63a.

[0188] The radius of curvature of the round portion 63c can be more than 0 and 0.5 mm or less, preferably more than 0 and 0.1 mm or less, and more preferably 0.01 mm to 0.05 m. When the radius of curvature of the round portion 63c satisfies the above numerical range, it is possible to prevent cracks from occurring at the lower part of the cutting groove 63 while the electrode 60 is running in a winding process or the like.

[0189] The lower inner angle θ of the plurality of divided sections 61 can increase from the core side toward the outer peripheral side. As an example, the lower inner angle θ of the plurality of divided sections 61 can increase gradually or stepwise from the core side toward the outer peripheral side. The lower inner angle θ is the angle between a straight line extending from the bottom 63a of the cutting groove 63 and a straight line extending from the side portion 53b of the divided section 61. When the divided section 61 is symmetric about the left and right, the lower inner angles θ on the left and right are substantially the same.

[0190] If the radius of the electrode assembly increases, the radius of curvature increases. If the lower inner angle θ of the segment 61 increases with the increase in the radius of the electrode assembly, when the segment 61 is bent, the stress generated in the radial and circumferential directions can be relieved. Also, if the lower inner angle θ increases, when the segment 61 is bent, both the area overlapping with the inner segment 61 and the number of overlapping layers increase, so that the welding strength can be ensured uniformly in the radial and circumferential directions, and the bent surface region can be formed flat.

[0191] Preferably, the lower inner angle θ can be determined by the radius of the winding turn where the segment 61 is located and the width D of the segment 61.

[0192] FIG. 7f is a schematic diagram for explaining the mathematical formula for determining the lower inner angle θ of the segment 61.

[0193] Referring to FIG. 7f, it is ideal that the sides of the segment 61 coincide with the line segments AE and DE that connect the center E of the core with A and D which are the two ends of the line segment AD corresponding to the width D of the segment 61.

[0194] When the sides of the segment 61 extend in the most ideal direction, the lower inner angle θ of the segment 61 refer can be approximately determined from the width D of the segment 61 and the radius r of the winding turn where the segment 61 is located using the following mathematical formula 4 when assuming that the line segment EF is approximately equal to the line segments AE and DE.

[0195]

Equation

[0196] The angle of the mathematical formula 4 is the lower inner angle θ of the segment 61 referThis is the ideal reference angle. On the other hand, a separation pitch P exists between adjacent segment sections 61 located in the same turn. The length of the separation pitch P is denoted by p. Because the separation pitch P exists between adjacent segment sections 61, a tolerance of 50% of the separation pitch P can be given to the lower interior angle θ. That is, the width of the upper edge BC of the segment section 61 can increase by a maximum of p / 2 up to the upper edge B'C'. The lower interior angle θ', with the tolerance reflected, can be expressed by the following equation 5. Lower interior angle θ refer ∠BAG is the ideal reference angle, and the lower interior angle θ' is the angle ∠B'AG' which reflects the tolerance due to the separation pitch P. In equation 5, H is the height of the segment 61, and p corresponds to the separation pitch.

[0197]

number

[0198] Preferably, the lower interior angle θ of each segment 61 located at each winding turn of the electrode assembly can satisfy the following equation 6. This allows for smooth bending without interference between adjacent segments 61 in the circumferential direction when the segment 61 is bent toward the center of the core of the electrode assembly.

[0199]

number

[0200] For example, if the electrode 60 forms a winding structure with a diameter of 22 mm and a core radius of 4 mm, the lower inner angle of the segment 61 can be gradually or stepwise increased in the range of 60° to 85° in the height-variable section.

[0201] As another example, multiple subsections 61 may have a lower interior angle θ that gradually or stepwise increases from the core side to the outer periphery side in groups of one or more.

[0202] On the other hand, the lower interior angle on the left side of the segment 61 does not have to be equal to the lower interior angle on the right side. Nevertheless, it is still possible to design it so that at least one of the lower interior angles θ satisfies the above equation 6.

[0203] Referring further to Figure 7a, the width d of the first part B1 is B1 The design is such that when the segment 61 of the third part B2 is bent toward the core, the core of the electrode assembly is exposed outward by more than 90% relative to its diameter. B1 The width d of the first portion B1 may increase in proportion to the bend length of the segment 61 of group 1. The bend length corresponds to the length from the bend point to the upper edge of the segment 61. Preferably, when the electrode 60 is used to manufacture an electrode assembly of a cylindrical battery of form factor 4680, the width d of the first portion B1 B1 This can be set to 180 mm to 350 mm depending on the diameter of the electrode assembly core and the height of the segment 61 included in group 1.

[0204] The bending point of the segment 61 can be set on a line passing through the bottom of the cutting groove 63 or at a point a predetermined distance above that line. If the segment 61 is bent toward the core at a point a predetermined distance from the bottom of the cutting groove 63, the radial superposition of the segment segments becomes easier. When the segment 61 is bent, the outer segment segments press against the inner segment segments with respect to the center of the core. At this time, if the bending point is a predetermined distance from the bottom of the cutting groove 63, the superposition of the segment segments becomes easier as the inner segment segments are pressed in the winding axis direction by the outer segment segments. The separation distance of the bending point is preferably 1 mm or less. Since the minimum height of the segment segment is 2 mm, the ratio of the separation distance of the bending point to the minimum height may be 50% or less.

[0205] In one example, the width of each segment group may be designed to constitute the same winding turn of the electrode assembly. Here, the winding turns can be counted relative to the end of the first portion B1 in the wound state of the electrode 60.

[0206] In other modifications, the width of each segment group may be designed to constitute at least one winding turn of the electrode assembly.

[0207] In still another modification, the width and / or height and / or separation pitch of the segmented pieces 61 belonging to the same segmented piece group may increase or decrease gradually and / or stepwise and / or irregularly within the group or between adjacent groups.

[0208] Groups 1 to 8 are merely an example of the segmented piece groups included in the third portion B2. The number of groups, the number of segmented pieces 61 included in each group, and the width of the group can be preferably adjusted so that the segmented pieces 61 overlap multiplicatively to maximize the dispersion of stress during the bending process of the non-patterned portion 43 and sufficiently ensure the welding strength with the current collector.

[0209] In another modification, the height of the second portion B3 may decrease gradually or stepwise as in the first and second embodiments.

[0210] In still another modification, the slitting structure of the third portion B2 can be extended up to the second portion B3 (see the dotted line). In this case, the second portion B3 may also include a plurality of segmented pieces like the third portion B2. Preferably, the slitting structure of the second portion B3 may be substantially the same as the outermost segmented piece group of the third portion B2. In this case, the segmented pieces included in the second portion B3 and the third portion B2 may have substantially the same width, height, and separation pitch. As a modification, the segmented pieces of the second portion B3 may have a width and / or height and / or separation pitch larger than that of the third portion B2.

[0211] In the third portion B2, with reference to the winding direction of the electrode 60, the section where the height of the segmented piece 61 increases stepwise (groups 1 to 7) is defined as the height variable section of the segmented piece, and the last segmented piece group (group 8) may be defined as the height uniform section where the height of the segmented piece is maintained uniformly.

[0212] That is, in the third portion B2, when the height of the segmented piece 61 increases stepwise from h1 to h N up to, the section where the segmented pieces 61 having a height of h1 to h N-1 (N is a high index and a natural number of 2 or more) belong corresponds to the height variable section, and hN The section in which the segment 61 having a certain height is arranged corresponds to the uniform height section. The ratio of the variable height section to the uniform height section with respect to the length of the electrode 60 in the winding direction will be described later with reference to a specific embodiment.

[0213] When electrode 60 is used to manufacture an electrode assembly for a cylindrical battery of form factor 4680, the width d of the first part B1 is B1 The width can be 180-350mm. The width of Group 1 can be 35-40% of the width of Part 1 B1. The width of Group 2 can be 130-150% of the width of Group 1. The width of Group 3 can be 120-135% of the width of Group 2. The width of Group 4 can be 85-90% of the width of Group 3. The width of Group 5 can be 120-130% of the width of Group 4. The width of Group 6 can be 100-120% of the width of Group 5. The width of Group 7 can be 90-120% of the width of Group 6. The width of Group 8 can be 115-130% of the width of Group 7. The width of Part 2 B3 d B3 This can be 180-350 mm, similar to the width of the first section B1.

[0214] The reason why the widths of groups 1 to 8 do not show a constant increasing or decreasing pattern is that while the width of the segmental sections gradually increases from group 1 to group 8, the number of segmental sections within a group is limited to an integer, and the electrode thickness has a slight deviation in the winding direction. Therefore, the number of segmental sections may decrease in a particular segmental section group. Consequently, the width of the groups may show an irregular pattern of change from the core side to the outer circumference, as illustrated above.

[0215] In other words, when the winding widths for three consecutively adjacent segment groups in the circumferential 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.

[0216] In the specific example described above, groups 4 to 6 fall under the above case. The ratio of group 5 to group 4 is 120-130%, and the ratio of group 6 to group 5 is 100-120%, which is smaller than 120-130%.

[0217] In further variations, when the plain portion 43 of the electrode 60 has a segmented structure, the electrode 60 may include segmented section omission sections 64 in which some of the multiple segmented sections are omitted regularly or irregularly, as shown in Figure 7g.

[0218] Preferably, there may be multiple subsection omission sections 64. For example, the width of the subsection omission section 64 may be constant from the core side to the outer periphery side. As another example, the width of the subsection omission section 64 may increase or decrease regularly or irregularly from the core side to the outer periphery side. Preferably, the height of the blank area in the subsection omission section 64 may correspond to the height of the first section B1 and / or the second section B3.

[0219] The number of segmental segments 61 present in the segmental segment omission section 64 can be at least one. The electrode 60 may include blank sections, as shown in Figure 7g, where the number of segmental segments 61 present in the segmental segment omission section 64 increases from the core toward the outer circumference.

[0220] Preferably, the width of the segment omission section 64 can be set such that, as shown in Figure 7h, when the electrode 60 is wound, the segment located at each winding turn is located within a predetermined independent region 66 with respect to the center C of the core of the electrode assembly 65.

[0221] In other words, when the electrode assembly 65 is viewed in the direction of the winding axis, the multiple segments 61 can be located within multiple independent regions 66 with respect to the center C of the core. The number of independent regions 66 can vary to two, three, four, five, or the like.

[0222] Preferably, the independent region 66 may be sector-shaped. In this case, the angles between the independent regions 66 may be substantially the same. Also, the inscribed angle δ of the independent region 66 may be 20° or more, selectively 25° or more, selectively 30° or more, selectively 35° or more, or selectively 40° or more.

[0223] In the modified example, the independent region 66 may have the form of a geometric figure such as a square, rectangle, parallelogram, or trapezoid.

[0224] In one embodiment of the present invention, the shape of the segment 61 can be varied in many ways.

[0225] On the other hand, in the electrode assembly 65 of the present invention, a plurality of segmental segments 61 are bent radially to form a bent surface region (F in Figure 10b), and current collectors (144, 176 in Figure 23) can be welded to the bent surface region F. If vibration is applied to the electrode assembly 65 depending on the battery's operating environment, or if swelling occurs in the electrode assembly 65 due to repeated charge-discharge cycles, stress will increase at the welded areas of the current collectors 144, 176, potentially inducing cracks in the segmental segments 61 welded to the current collectors and the nearby active material layer 42 that can cause internal short circuits. For reference, vibration can be applied to the battery from a load device (e.g., an electric vehicle).

[0226] The electrode 60 according to the fourth embodiment of the present invention may include a structure that can relieve stress by providing a cut-out portion 62 at a point sufficiently separated from the active material layer 42, where the plain portion 43 and / or the segmented portion 61 break when a stress exceeding a critical value occurs at the welded portion of the current collector.

[0227] Figure 7i is a plan view showing a first example in which a cut-out portion 62 is formed on the electrode 60 according to the fourth embodiment of the present invention.

[0228] Referring to Figure 7i, in the electrode 60 of the fourth embodiment, the plain portion 43 includes a plurality of independently bendable segments 61, and at least a portion of the plain portion 43 provided with the plurality of segments 61 may include a cut-off portion 62 extending in one direction parallel to the winding direction (X-axis).

[0229] The cut portion 62 may be provided in the plain area 43 that exists between the bottom 63a of the cutting groove 63 and the active material portion on which the active material layer 42 is formed.

[0230] The cut-off portion 62 can be formed continuously along one direction parallel to the winding direction (X-axis) of the electrode assembly in the area of ​​the blank portion 43 where the multiple sub-sections 61 are provided.

[0231] Preferably, the distance from the bottom 63a of the cutting groove 63 to the cut portion 62 may be shorter than the distance from the cut portion 62 to the insulating coating layer 44. In this case, the point at which the plain portion 43 breaks can be separated from the active material layer 42 to the maximum extent possible, thereby preventing damage to the active material layer 42 and the insulating coating layer 44 when the plain portion 43 breaks.

[0232] The separation distance between the cut portion 62 and the bottom 63a of the cutting groove 63 may be between 0.1 mm and 1.9 mm. If the separation distance is less than 0.1 mm, cracks are likely to occur even with small impacts, not just at the critical stress level. If the separation distance is 1.9 mm or more, the critical stress level may be too high, and the fracture region may extend beyond the cut portion and reach the active material layer.

[0233] The cut-out portion 62 may include an arrangement of multiple punch holes 62h along the winding direction (X-axis) of the electrode assembly. For example, the shape of the punch holes 62h may be circular. The shape of the punch holes 62h can also be replaced with a square, rhombus, triangle, ellipse, or the like.

[0234] Although not shown in the diagram, the cut-out portion 62 may include an arrangement of multiple grooves along the winding direction (X-axis) of the electrode assembly. Here, the grooves represent areas where the thickness of the plain portion 43 is locally reduced. The shape of the grooves may be circular, square, rhombus, triangular, elliptical, etc.

[0235] Figure 7j is a plan view showing a second example in which a cut-out portion 62 is formed on the electrode 60 according to the fourth embodiment of the present invention.

[0236] Referring to Figure 7j, the cut-off portion 62 can be formed discontinuously along one direction parallel to the winding direction (X-axis) of the electrode assembly in the area of ​​the blank portion 43 which is provided with a plurality of segmented pieces 61.

[0237] In other words, the cut portion 62 may include a plurality of sub-cut portions 62s formed discontinuously along one direction parallel to the winding direction (X-axis) of the electrode assembly, and the plurality of sub-cut portions 62s may have substantially the same height in the winding axis direction (Y-axis).

[0238] In one embodiment, the length of the sub-cut portion 62s may gradually increase along the winding direction (X-axis) of the electrode assembly in at least a portion of the plain portion 43. Alternatively, the length of the sub-cut portion 62s may gradually decrease along the winding direction (X-axis) of the electrode assembly in at least a portion of the plain portion 43.

[0239] In other embodiments, in at least a portion of the plain area 43, the separation distance between adjacent sub-cut portions 62s along the winding direction (X-axis) of the electrode assembly may gradually increase. Alternatively, in at least a portion of the plain area 43, the separation distance between adjacent sub-cut portions 62s along the winding direction (X-axis) of the electrode assembly may gradually decrease.

[0240] Preferably, a section of plain section 43 in which the length of the sub-cut section 62s is relatively increased or the distance between adjacent sub-cut sections 62s is relatively decreased may correspond to a winding section in which the stress applied to the segment 61 welded to the current collector increases due to vibration or swelling of the electrode assembly.

[0241] Figures 7k and 7l are plan views showing a third and fourth example, respectively, in which a cut-out portion 62 is formed on the electrode 60 according to the fourth embodiment of the present invention.

[0242] Referring to Figures 7k and 7l, the cut-out portion 62 includes a plurality of sub-cut-out portions 62s formed discontinuously along one direction parallel to the winding direction (X-axis) of the electrode assembly, and the plain portion 43 may include regions in which the heights of the sub-cut-out portions 62s in the winding axis direction (Y-axis) are different.

[0243] As an example, as shown in Figure 7k, the cut portion 62 includes a plurality of sub-cut portions 62s formed discontinuously along one direction parallel to the winding direction (X-axis) of the electrode assembly, and the plain portion 43 may include a section along the winding direction (X-axis) of the electrode assembly in which the distance between the bottom 63a of the cutting groove 63 and the sub-cut portions 62s gradually decreases.

[0244] As another example, as shown in Figure 7l, the cut section 62 may include a plurality of sub-cut sections 62s formed discontinuously along one direction parallel to the winding direction (X-axis) of the electrode assembly, and the plain section 43 may include a section along the winding direction (X-axis) of the electrode assembly in which the distance between the bottom 63a of the cutting groove 63 and the sub-cut sections 62s gradually increases.

[0245] Preferably, the plain section 43 where the distance between the sub-cut section 62s and the bottom 63a of the cutting groove 63 is relatively reduced can correspond to a winding section where the stress applied to the segment 61 welded to the current collector increases due to vibration or swelling of the electrode assembly.

[0246] Figure 7m is a plan view showing a fifth example in which a cut-out portion 62 is formed on the electrode 60 according to the fourth embodiment of the present invention.

[0247] Referring to Figure 7m, the cutting section 62 includes a plurality of sub-cutting sections 62s, and the plurality of sub-cutting sections 62s may be provided at positions corresponding to the bottom 63a of the cutting groove 63.

[0248] Preferably, the sub-cut portion 62s does not need to intersect with the imaginary line L that passes through the center of the upper edge and the center of the lower edge of the segment 61.

[0249] The sub-cutting section 62s and the imaginary line L can be separated by 50% or more, based on the distance between the bottom 63a of the cutting groove 63 and the imaginary line L.

[0250] The region where the sub-cut portion 62s is located experiences a localized increase in resistance. This is because the cross-sectional area of ​​the plain portion 43 where the sub-cut portion 62 is provided is reduced. According to the fifth example, the region in which the sub-cut portion 62s overlaps with the segment 61 that forms the current path can be reduced, thereby suppressing the increase in resistance caused by the sub-cut portion 62s.

[0251] Figure 7n is a plan view showing a sixth example in which a cut-out portion 62 is formed on the electrode 60 according to the fourth embodiment of the present invention.

[0252] Referring to Figure 7n, the cut section 62 includes a plurality of sub-cut sections 62s, which may be arranged so as to overlap with the bottom 63a of the cutting grooves 63 provided on both sides of the segment 61 welded to the current collector.

[0253] Preferably, the sub-cut portion 62s does not need to intersect with the imaginary line L that passes through the center of the upper edge and the center of the lower edge of the segment 61 welded to the current collector.

[0254] The sub-cutting section 62s and the imaginary line L can be separated by 50% or more, based on the distance between the bottom 63a of the cutting groove 63 and the imaginary line L.

[0255] In the segmentation section 61 welded to the current collector, the region near the virtual line L corresponds to the main path through which the charging current and discharge current flow. By preventing the sub-cutting section 62s from intersecting the virtual line L, it is possible to suppress the increase in the resistance of the segmentation section 61 that forms the current path due to the sub-cutting section 62s.

[0256] In the first to sixth examples described above, the height of the segment 61 may be substantially the same along the winding direction (X-axis) of the electrode assembly, contrary to what is shown in the figures. Therefore, when the electrode 60 is provided with a segment 62, the height of the segment 61 may vary along the winding direction (X-axis) of the electrode assembly or be kept constant.

[0257] Figure 8a is a plan view showing the structure of the electrode 70 according to the fifth embodiment of the present invention.

[0258] Referring to Figure 8a, the electrode 70 of the fifth embodiment is substantially identical in configuration to that of the above-described embodiment, except that the shape of the segment 61' differs. Therefore, unless otherwise specified, the configuration of the fourth embodiment can be similarly applied to the fifth embodiment.

[0259] The segment 61' has a geometric shape in which the upper width and the lower width are approximately the same. Preferably, the segment 61' may be rectangular.

[0260] Figure 8b shows the definitions of the width, height, and spacing pitch of the rectangular section 61'.

[0261] Referring to Figure 8b, the width D, height H, and separation pitch P of the segment 61' are set to sufficiently increase the number of overlapping layers of the plain section 43 and to prevent abnormal deformation of the plain section 43 in order to prevent the plain section 43 from tearing during bending and to improve the welding strength with the current collector. Abnormal deformation refers to the plain section below the bending point collapsing and deforming irregularly without being able to maintain a straight line.

[0262] The width D of the segment 61' is defined by the distance between two points where two straight lines extending from the side edges of the segment 61' intersect with a straight line extending from the bottom 63a of the cutting groove 63. The height H of the segment 61' is defined by the shortest distance between the uppermost edge of the segment 61' and a straight line extending from the bottom 63a of the cutting groove 63. The spacing pitch P of the segment 61' is defined by the distance between two points where a straight line extending from the bottom 63a of the cutting groove 63 intersects with two straight lines extending from the two side edges 63b connected to the bottom 63a. When the side edges 63b and / or the bottom 63a are curves, the straight lines can be replaced by tangents extending from the intersection of the side edges 63b and the bottom 63a to the side edges 63b and / or the bottom 63a.

[0263] Preferably, the conditions relating to the width D, height H, and separation pitch P of the segment 61' are substantially the same as those of the fourth embodiment described above, so repeated explanations are omitted. However, since the segment 61' is rectangular in shape, the lower interior angle of the segment 61' may be a constant 90°.

[0264] Similar to the electrode 60 of the fourth embodiment, the electrode 70 of the fifth embodiment may also include segment omission sections 64 in which some of the multiple segments are omitted regularly or irregularly, as shown in Figure 8c.

[0265] Furthermore, when the electrode 70, which includes the segment omitted section 64, is wound up as an electrode assembly, the segment may be located within multiple independent regions 66, as shown in Figure 7h.

[0266] As in the fourth and fifth embodiments, when the third portion B2 and the second portion B3 include a plurality of subsections 61, 61', the shape of each subsection 61, 61' can be varied in many ways.

[0267] Preferably, the section can be deformed into various forms while satisfying at least one of the following conditions.

[0268] Condition 1: The width of the bottom is wider than the width of the top.

[0269] Condition 2: The width of the bottom and the width of the top are equal.

[0270] Condition 3: The width is maintained at a constant level from bottom to top.

[0271] Condition 4: The width decreases from the bottom to the top.

[0272] Condition 5: The width decreases from the bottom to the top, then increases.

[0273] Condition 6: The width increases from the bottom to the top, then decreases.

[0274] Condition 7: The width increases from the bottom to the top and then remains constant.

[0275] Condition 8: The width decreases from the bottom to the top and then remains constant.

[0276] Condition 9: The interior angle on one side of the lower section is the same as the interior angle on the other side.

[0277] Here, the interior angle can be defined as the angle formed by the side of the segment with respect to the width direction of the lower part of the segment. If the side is a curve, the interior angle is defined as the angle between the tangent line drawn at the lowest point of the curve and the width direction of the lower part of the segment.

[0278] Condition 10: The interior angle on one side of the lower section is different from the interior angle on the other side.

[0279] Condition 11: The interior angle on one side of the lower section and the interior angle on the other side of the lower section are acute, right, or obtuse, respectively.

[0280] Condition 12: It is symmetrical with respect to the winding axis direction.

[0281] Condition 13: It is asymmetrical with respect to the winding axis direction.

[0282] Condition 14: The sides are straight.

[0283] Condition 15: The sides are curved.

[0284] Condition 16: The sides are convex outwards.

[0285] Condition 17: The sides are convex inward.

[0286] Condition 18: The upper and / or lower corners are structured such that two straight lines intersect.

[0287] Condition 19: The upper and / or lower corners are structured in which a straight line and a curve intersect.

[0288] Condition 20: The upper and / or lower corners are structured in a way that curves intersect.

[0289] Condition 21: The top and / or bottom corners are rounded.

[0290] Figure 9 is an illustrative diagram showing the shape of a section according to a modified form of the present invention.

[0291] As illustrated, the section can have a variety of geometric shapes with a dotted line connecting the bottoms of the cutting grooves on both sides as its base. The geometric shape has a structure in which at least one straight line, at least one curve, or a combination thereof is connected. For example, the section can have a variety of shapes such as polygons, rounded patterns, or combinations thereof.

[0292] Specifically, the segment can be a symmetrical trapezoid (circle a); an asymmetrical trapezoid (circle b); a parallelogram (circle c); a triangular shape (circle l); a pentagon (circle k); an arc shape (circle e); or an ellipse (circle f).

[0293] The shape of the section is not limited to that shown in Figure 9, and can be modified to other polygonal shapes, other round shapes, or combinations thereof, so as to satisfy at least one of the conditions 1 to 21 described above.

[0294] In the polygonal shapes of the segmental sections, circles a, b, c, k, and l, the upper corners and / or lower corners may be the shape of two intersecting straight lines or rounded (see the enlarged view of the upper and lower corners of circle a).

[0295] In the polygonal shapes of the segmental sections, circles a, b, c, k, and l, and the round shapes of the segmental sections, circles e and f, the interior angles θ1 and θ2 on one side of the lower section may be the same or different, and these interior angles θ1 and θ2 on the other side may be acute, right, or obtuse, respectively. An interior angle is the angle between the base and the sides of a geometric figure. When the sides are curves, straight lines may be replaced by tangents extending from the intersection of the base and the sides.

[0296] The shape of the sides of polygonal segments can be varied in many ways.

[0297] For example, the side of morphological circle a of the segmental section can be transformed into a curve that bulges outward, like morphological circle d, or into a curve that is concave inward, like morphological circle g or circle j.

[0298] As another example, the side of morphological circle a of the segmental section can be deformed into a rib line that is concave inward, like morphological circle h or circle i. Although not shown, the side of morphological circle a of the segmental section can also be deformed into a rib line that bulges outward.

[0299] In the morphological forms of the segment sections, round d, round g, round j, round h, and round i, in which the sides are deformed in various ways, the interior angle θ1 on one side and the interior angle θ2 on the other side of the lower section are either the same or different, and the interior angles θ1 and θ2 on the other side of the lower section can be acute, right, or obtuse, respectively.

[0300] The width of the segment can exhibit diverse patterns of change from the bottom to the top.

[0301] As one example, the width of the segment may be kept constant from bottom to top (morphology circle c). As another example, the width of the segment may gradually decrease from bottom to top (morphology circles a, b, d, e, f, and g). As yet another example, the width of segment 61 may gradually decrease from bottom to top and then increase (morphology circles i and j). As yet another example, the width of the segment may gradually increase from bottom to top and then decrease (morphology circle k). As yet another example, the width of the segment may gradually decrease from bottom to top and then be kept constant (morphology circle h). Although not shown, the width of the segment may gradually increase from bottom to top and then be kept constant.

[0302] On the other hand, among the segmental section shapes illustrated in Figure 9, the polygonal shape with a flattened top can be rotated by 180°. For example, when segmental section shapes a, b, d, or g are rotated by 180°, the width of the segmental section may gradually increase from the bottom to the top. As another example, when segmental section shape h is rotated by 180°, the width of the segmental section may be kept constant from the bottom to the top and then gradually increase.

[0303] In the above-described embodiment (modified form), according to another embodiment of the present invention, it is also possible to change the shape of the subsections 61, 61' along the region of the third part B2. For example, a round shape (e.g., semicircular, elliptical, etc.) that is advantageous for stress distribution can be applied to sections where stress is concentrated, and a polygonal shape (e.g., quadrilateral, trapezoid, parallelogram, etc.) that maximizes the area can be applied to sections where stress is relatively low.

[0304] In other embodiments, the multiple sections may have different shapes individually, in groups, or in groups of two or more, along one direction parallel to the winding direction of the electrode assembly.

[0305] In the above-described embodiment (modified form), the segmentation structure of the third part B2 can also be applied to the first part B1. However, if the segmentation structure is applied to the first part B1, when the segmented pieces 61, 61' of the third part B2 are bent due to the radius of curvature of the core, there is a risk of reverse forming occurring, where the end of the first part B1 bends outward. Therefore, it is preferable not to apply the segmentation structure to the first part B1, or, if the segmentation structure is applied, to adjust the width and / or height and / or spacing pitch of the segmented pieces 61, 61' to a level that does not cause reverse forming, taking into account the radius of curvature of the core.

[0306] Furthermore, according to yet another aspect of the present invention, after the electrodes 60 and 70 are wound up as an electrode assembly, the segments exposed on the upper and lower sides of the electrode assembly can overlap in multiple layers along the radial direction of the electrode assembly to form a bent surface region.

[0307] Figure 10a is a schematic diagram showing a cross-section of the bent surface region F formed when the segment 61 is bent toward the core C side of the electrode assembly 80. In Figure 10a, the cross-section of the bent surface region F is shown only on the left side with respect to the winding axis of the electrode assembly 80. The bent surface region F can be formed on both the upper and lower parts of the electrode assembly 80. Figure 10b is a schematic perspective view showing the electrode assembly 80 on which the bent surface region F is formed.

[0308] Referring to Figures 10a and 10b, the bent surface region F has a structure in which the segmental segments 61 are superimposed in multiple layers in the winding axis direction. The superposition direction is the winding axis direction (Y axis). Section circle 1 is a segmental segment omitted section (first part B1) where there are no segmental segments, and sections circle 2 and 3 are sections where winding turns containing segmental segments are located. Section circle 2 is a height variable section in which the height of the segmental segments 61 changes, and section circle 3 is a height uniform section in which the height of the segmental segments is maintained uniformly up to the outer circumference of the electrode assembly. As will be described later, the radial lengths of sections circle 2 and section circle 3 may change. On the other hand, a plain section (second part B3) included in at least one winding turn, including the outermost winding turn, does not have to contain a segmental segment structure. In this case, the second part B3 can be excluded from section circle 3.

[0309] In section 2, the height of the segment 61 is equal to the radius r1~r of the electrode assembly 80. N Minimum height h1 (=h) in the interval min ) from maximum height h N ( = h max ) can change in stages up to r. The height-variable interval in which the height of the segment 61 changes is r1 to r N The radius is r. N From the radius R of the electrode assembly 80, the height of the segment 61 is h N It is maintained uniformly. Uniform height means that the height deviation is within 5%.

[0310] At any radial position in section circle 2 and section circle 3, the number of layers of subsection 61 varies depending on the radial position. Also, the number of layers of subsection 61 depends on the width of section circle 2 and the minimum height h1 and maximum height h of the subsection in the height-variable section of subsection 61. N Furthermore, it can vary depending on the change in height Δh of the segment 61. The number of stacked segments 61 is the number of segments that intersect a virtual line drawn in the winding axis direction from an arbitrary radial position of the electrode assembly 80.

[0311] Preferably, the height, width, and spacing pitch of the segmentation segments 61 can be adjusted according to the radius of the winding turn containing the segmentation segments 61, thereby optimizing the number of segments stacked at each position in the bent surface region F to match the required welding strength of the current collector.

[0312] First, when the minimum height h1 of the segment 61 is the same in the height-variable interval (circle 2), the maximum height h of the segment 61 N The following will explain, with specific examples, how the number of layers of the segment 61 changes along the radial direction of the folded surface region F due to the change in [the specified parameter].

[0313] Electrode assemblies for Examples 1-1 to 1-7 were prepared. The electrode assemblies in the examples have a radius of 22 mm and a core diameter of 4 mm. The positive and negative electrodes included in the electrode assemblies have the electrode structure shown in Figure 7a. That is, the shape of the segment is trapezoidal. The second part B3 of the positive and negative electrodes does not include the segment. The length of the second part B3 is 3% to 4% of the total length of the electrode. The positive electrode, negative electrode, and separator membrane were wound using the method described with reference to Figure 2. The number of winding turns is between 48 and 56 turns, but the number of winding turns in the examples is 51 turns. The thicknesses of the positive electrode, negative electrode, and separator membrane are 149 μm, 193 μm, and 13 μm, respectively. The thicknesses of the positive and negative electrodes include the thickness of the active material layer. The thicknesses of the positive electrode current collector and negative electrode current collector are 15 μm and 10 μm, respectively. The lengths of the positive and negative electrodes in the winding direction are 3948 mm and 4045 mm, respectively.

[0314] In each embodiment, the minimum height of the segment 61 was set to 3 mm, starting from a radius of 5 mm in the variable height section of the segment 61 (circle 2). In addition, in each embodiment, the height of the segment 61 was increased by 1 mm for every 1 mm increase in radius, and the maximum height of the segment 61 varied from 4 mm to 10 mm.

[0315] Specifically, in Example 1-1, the height variable section (circle 2) of the segment 61 is 5 mm to 6 mm, and the height of the segment 61 changes from a radius of 3 mm to 4 mm. In Example 1-2, the height variable section (circle 2) of the segment 61 is 5 mm to 7 mm, and the height of the segment 61 changes from 3 mm to 5 mm. In Example 1-3, the height variable section (circle 2) of the segment 61 is 5 mm to 8 mm, and the height of the segment 61 changes from 3 mm to 6 mm. In Example 1-4, the height variable section (circle 2) of the segment 61 is 5 mm to 9 mm, and the height of the segment 61 changes from 3 mm to 7 mm. In Example 1-5, the height variable section (circle 2) of the segment 61 is 5 mm to 10 mm, and the height of the segment 61 changes from 3 mm to 8 mm. In Examples 1-6, the height of the segment 61 is variable in the range of 5 mm to 11 mm (circle 2), and the height of the segment 61 varies from 3 mm to 9 mm. In Example 1-7, the height of the segment 61 is variable in the range of 5 mm to 12 mm (circle 2), and the height of the segment 61 varies from 3 mm to 10 mm. In Examples 1-1 to 1-7, the height of the segment 61 is uniform from the radius corresponding to the upper limit of the height variable range (circle 2) to the outer circumference. For example, in Example 1-7, the height of the segment 61 is uniformly 10 mm from a radius of 12 mm to 22 mm. On the other hand, in the comparative example electrode assembly, the height of the segment 61 was maintained at a single height of 3 mm from a radius of 5 mm to a radius of 22 mm.

[0316] Figure 10c is a graph showing the results of counting the number of layered segments along the radial direction in the folded surface region F of the positive electrode formed on the upper part of the electrode assemblies according to Examples 1-1 to 1-7 and the comparative example. Substantially the same results are shown for the folded surface region of the negative electrode. The horizontal axis of the graph represents the radius relative to the center of the core, and the vertical axis represents the number of layered segments counted at each radial point. The same applies to Figures 10d and 10e, which will be described later.

[0317] Referring to Figure 10c, the uniform number of layers of the segmental segments interval b1 appears in common in Examples 1-1 to 1-7 and Comparative Example 1. The uniform number of layers interval b1 is the radius interval of the flattened region in each graph. The length of the uniform number of layers interval b1 increases as the maximum height of the segmental segments decreases, with the uniform number of layers interval b1' in the Comparative Example being the longest. On the other hand, the number of layers of the segmental segments is equal to the maximum height of the segmental segments h N It increases as the value increases. That is, the maximum height of the segment h N As the radius increases and the width of the variable-height section of the segment (circle 2) increases, the number of stacked segment segments increases, while the width of the uniform-number-of-stacks section b1 decreases. Outside the uniform-number-of-stacks section b1, a decreasing-number-of-stacks section b2 appears where the number of stacked segment segments decreases as the radius increases. The decreasing-number-of-stacks section b2 is a radial section where the number of stacked segment segments decreases as the radius of the electrode assembly increases. The uniform-number-of-stacks section b1 and the decreasing-number-of-stacks section b2 are adjacent in the radial direction and are complementary to each other. That is, if the length of one section increases, the length of the other section decreases. Also, in the decreasing-number-of-stacks section b2, the amount of decrease in the number of stacks is proportional to the distance from the uniform-number-of-stacks section b1.

[0318] From the perspective of the number of layers of segmentation segments, Examples 1-1 to 1-7 have 10 or more layers of segmentation segments in the uniform segmentation segmentation segmentation segmentation segment b1. The region with 10 or more layers of segmentation segments can be set as a preferred welding target region. The welding target region is the section in which at least a portion of the current collector is welded.

[0319] In Examples 1-1 to 1-7, the uniform layering section b1 begins at the radius point where the variable-height section of the segment (circle 2) begins. That is, the variable-height section (circle 2) starts at a radius of 5 mm and extends outwards.

[0320] Table 4 below shows the results of calculations for Examples 1-1 to 1-7 and Comparative Example 1, including the ratio of the length of the segment omission section (c, circle 1 in Figure 10a) to the radius of the electrode assembly excluding the core (ba) relative to the positive electrode; the ratio of the length of the uniform number of layers section b1 to the length from the radius point where the uniform number of layers section begins (5 mm) to the outermost point of the electrode assembly (22 mm) (f) (e / f); the ratio of the length of the segment height variable section (d) to the length from the radius point where the uniform number of layers section begins (5 mm) to the outermost point of the electrode assembly (22 mm) (f) (d / f); the ratio of the length of the electrode region corresponding to the segment omission section (first part B1) to the total length of the electrode (h); the ratio of the length of the electrode region corresponding to the height variable section to the total length of the electrode (i); and the ratio of the electrode region corresponding to the height uniform section to the total length of the electrode (i).

[0321] The negative electrode is substantially identical to the positive electrode in all other parameters, except that it shows a difference of 0.1-1.2% with respect to parameter h. The sum of ratios h, i, and j is slightly different from 100%. This is because there is a section without a segment in the second part B3, which corresponds to the plain outer circumference of the electrode. For example, in Example 1-1, there is no segment in the second part B3, which corresponds to approximately 4% of the total length of the electrode. In Table 4, a-f are parameters based on the radial length, and h, i, and j are parameters based on the longitudinal direction of the electrode before it is wound as an electrode assembly. Also, the parameters corresponding to ratios (%) are values ​​rounded to the first decimal place. These are substantially the same in Tables 5 and 6 described later.

[0322] [Table 4]

[0323] Referring to Examples 1-1 to 1-7 in Table 4, the number of layers of segmentation segments ranges from 11 to 26, and the ratio of the height-variable section (d) to the radius section (f) containing segmentation segments (d / f) is 6% to 41%. The ratio of the uniform number of layers section (e / f) to the radius section (f) containing segmentation segments (e) is 47% to 82%. The ratio of the segmentation-omitted section (c, circle 1 in Figure 10a) to the radius (ba) of the electrode assembly excluding the core (c / (ba)) is 15%. The ratio of the length of the electrode region corresponding to the segmentation-omitted section (first part B1) to the total length of the electrode is 6%, the ratio of the length of the electrode region corresponding to the height-variable section to the total length of the electrode is 3% to 32%, and the ratio of the length of the electrode region corresponding to the height-uniform section to the total length of the electrode is 59% to 87%. The number of layers (g) in the uniform number of layers section is 10 or more in all Examples 1-1 to 1-7. The uniform layer count section (e) decreases as the variable section height section (d) increases, but the number of layers of the section (g) increases in the uniform layer count section (e). Preferably, the uniform layer count section (e) where the number of layers of the section (g) is 10 or more can be set as a welding target area.

[0324] Cylindrical batteries with form factors 1865 and 2170 have an electrode assembly radius of approximately 9mm to 10mm. Therefore, compared to conventional cylindrical batteries, it is not possible to secure a radial length of 17mm in the segment section (f) and a uniform stacking section (e) with 10 or more stacking segments in the 8mm to 14mm section compared to conventional cylindrical batteries. This is because, in conventional cylindrical batteries, if the core radius is designed to be 2mm, the same as in Examples 1-1 to 1-7, the radial section in which segment sections can be placed is effectively only 7mm to 8mm. Furthermore, in conventional cylindrical batteries, the length of the electrodes in the winding direction is in the 600mm to 980mm range. Such short electrode lengths are only about 15% to 24% of the electrode lengths used in Examples 1-1 to 1-7 (positive electrode 3948mm, negative electrode 4045mm). Therefore, the numerical ranges for parameters h, i, and j cannot be easily derived from the design specifications of conventional cylindrical batteries.

[0325] Next, in the section with variable section height (circle 2 in Figure 10a), the maximum height of the section h N When the minimum height h1 of the segment is the same, we will explain, with specific examples, how the number of stacked segments changes along the radial direction of the folded surface region F due to the change in the minimum height h1 of the segment.

[0326] The electrode assemblies of Examples 2-1 to 2-5 have a radius of 22 mm and a core C diameter of 4 mm. The minimum height h1 in the height-variable section of the segment 61 (circle 2 in Figure 10a) is the same as 4 mm, and the maximum height h N The width was varied from 6 mm to 10 mm in 1 mm increments. Therefore, in the electrode assemblies of Examples 2-1 to 2-5, the width of the variable section height section (circle 2 in Figure 10a) is 2 mm, 3 mm, 4 mm, 5 mm, and 6 mm, respectively, and the section omitted section (circle 1 in Figure 10a) is a radius section from 2 mm to 6 mm.

[0327] The electrode assemblies of Examples 3-1 to 3-4 have a radius of 22 mm and a core diameter of 4 mm. The minimum height h1 in the height-variable section of the segment 61 (circle 2 in Figure 10a) is the same as 5 mm, and the maximum height h N The width was varied from 7 mm to 10 mm in 1 mm increments. Therefore, in the electrode assemblies of Examples 3-1 to 3-4, the width of the variable section height section (circle 2 in Figure 10a) is 2 mm, 3 mm, 4 mm, and 5 mm, respectively, and the section omitted section (circle 1 in Figure 10a) is a radius section from 2 mm to 7 mm.

[0328] The electrode assemblies of Examples 4-1 to 4-3 have a radius of 22 mm and a core C diameter of 4 mm. The minimum height h1 in the height-variable section of the segment 61 (circle 2 in Figure 10a) is the same as 6 mm, and the maximum height h N The width was varied from 8 mm to 10 mm in 1 mm increments. Therefore, in the electrode assemblies of Examples 4-1 to 4-3, the width of the variable section height section (circle 2 in Figure 10a) is 2 mm, 3 mm, and 4 mm, respectively, and the section omitted section (circle 1 in Figure 10a) is a radius section from 2 mm to 8 mm.

[0329] The electrode assemblies of Examples 5-1 to 5-2 have a radius of 22 mm and a core diameter of 4 mm. The minimum height h1 in the height-variable section of the segment 61 (circle 2 in Figure 10a) is the same as 7 mm, and the maximum height h N The width was varied in 1 mm increments from 9 mm to 10 mm. Therefore, in the electrode assemblies of Examples 5-1 to 5-2, the width of the variable section height section (circle 2 in Figure 10a) is 2 mm and 3 mm, respectively, and the section omitted section (circle 1 in Figure 10a) is a radius section from 2 mm to 9 mm.

[0330] Figure 10d is a graph showing the results of counting the number of stacked segments measured radially in the bent surface region F of the positive electrode formed on the upper part of the electrode assemblies according to Examples 2-1 to 2-5, Examples 3-1 to 3-4, Examples 4-1 to 4-3, Examples 5-1 and 5-2. The results are substantially the same for the bent surface region of the negative electrode.

[0331] In Figure 10d, graph (a) shows the results of counting the number of layers of subsections along the radial direction in the folded surface region F for Examples 2-1 to 2-5, graph (b) for Examples 3-1 to 3-4, graph (c) for Examples 4-1 to 4-3, and graph (d) for Examples 5-1 and 5-2.

[0332] Referring to Figure 10d, the uniform stacking interval b1 of the subsections appears in common in all examples. The uniform stacking interval b1 is the radius interval of the flattened region in the graph. The length of the uniform stacking interval b1 is equal to the maximum height h of the subsections when the minimum height h1 of the subsections is the same. N It increases as the decrease in the number of layers decreases. Also, the length of the uniform layering interval b1 is equal to the maximum height of the subsection h. N When these are the same, the number of layers of the subsection increases as the minimum height h1 of the subsection decreases. On the other hand, in the uniform layering interval b1, the number of layers of the subsection is equal to the maximum height h of the subsection. N The value increases as the value increases. In the example, a section b2 with a decreasing number of layers appears adjacent to a section b1 with a uniform number of layers.

[0333] In the example, the number of layers of the segment in the uniform layer number section b1 is 10 or more in all cases. Preferably, the region where the number of layers of the segment is 10 or more can be set as a preferred welding target region.

[0334] In the examples, the uniform layering section b1 starts from the radius point where the variable-height section of the segment (circle 2 in Figure 10a) begins. In Examples 2-1 to 2-5, the variable-height section of the segment (circle 2 in Figure 10a) starts at 6 mm and extends outward. In Examples 3-1 to 3-4, the variable-height section of the segment (circle 2 in Figure 10a) starts at 7 mm and extends outward. In Examples 4-3 to 4-3, the variable-height section of the segment (circle 2 in Figure 10a) starts at 8 mm and extends outward. In Examples 5-1 and 5-2, the variable-height section of the segment (circle 2 in Figure 10a) starts at 9 mm and extends outward.

[0335] Table 5 below shows the results of calculating various parameters for Examples 2-1 to 2-5, Examples 3-1 to 3-4, Examples 4-1 to 4-3, Examples 5-1 and 5-2, including the ratio (e / f) of the length of the uniform layer count section to the length from the radius point where the uniform layer count section begins (6mm, 7mm, 8mm, 9mm) to the outermost point of the electrode assembly (22mm), and the ratio (d / f) of the length of the variable segment height section (circle 2) to the length from the radius point where the uniform layer count section begins (6mm, 7mm, 8mm, 9mm) to the outermost point of the electrode assembly (22mm).

[0336] [Table 5]

[0337] Referring to Examples 2-5, 3-4, 4-3, and 5-2 in Table 5, along with Figures 10a and 10d, the maximum height h of the segment in the segment height variable section (circle 2) is shown. NAlthough the width is the same at 10 mm, the minimum height h1 of the segment increases by 1 mm each time, from 4 mm, 5 mm, 6 mm, to 7 mm, while the length of the height-variable section (circle 2) decreases by 1 mm each time, from 6 mm, 5 mm, 4 mm, to 3 mm. In the four examples, the ratio of the uniform layer count section (e / f) is highest in Example 2-5 at 69% and lowest in Example 5-2 at 38%, and the number of layers in the uniform layer count section is the same in all examples. From the results shown in Table 5, the maximum height h of the segment N When these values ​​are the same, it can be seen that as the minimum height h1 of the subsection decreases and the width of the variable height subsection section (circle 2) increases, the width of the uniform stacking section also increases proportionally. The reason for this is that the smaller the minimum length h1 of the subsection, the closer the radius point where the subsection begins is to the core, and the region where the subsections are stacked expands towards the core.

[0338] Referring to Table 5, it can be seen that the number of layers of segmentation segments ranges from 16 to 26, the ratio (d / f) of the segmentation segment with variable height (circle 2) is 13% to 38%, and the ratio (e / f) of the segmentation segment with a uniform number of layers is 31% to 69%. Furthermore, the ratio (c / (ba)) of the segmentation segment omitted section (circle 1) to the radius (ba) of the electrode assembly excluding the core is 20% to 35%. In addition, the ratio of the length of the electrode region corresponding to the segmentation segment omitted section (circle 1) to the total length of the electrode is 10% to 20%, the ratio of the length of the electrode region corresponding to the height-variable section (circle 2) to the total length of the electrode is 6% to 25%, and the ratio of the length of the electrode region corresponding to the height-uniform section (circle 3) to the total length of the electrode is 62% to 81%.

[0339] Cylindrical batteries with form factors 1865 and 2170 have an electrode assembly radius of approximately 9mm to 10mm. Therefore, as in the embodiment, it is not possible to secure a radial length of 13mm to 16mm in the segment section (f), and it is not possible to secure a length of approximately 4mm to 7mm in the segment omission section (c, circle 1) while simultaneously securing a length of 5mm to 11mm in the uniform stacking section (e) where the number of stacked segments is 10 or more. In conventional cylindrical batteries, if the core radius is designed to be the same as in the embodiment (2mm), the radial section in which segments can be placed is effectively only 7mm to 8mm. Furthermore, in conventional cylindrical batteries, the length of the electrodes in the winding direction is approximately 600mm to 980mm. Such short electrode lengths are only about 15% to 24% of the electrode lengths in the embodiment (positive electrode 3948mm, negative electrode 4045mm). Therefore, the numerical ranges for parameters h, i, and j cannot be easily derived from the design specifications of conventional cylindrical batteries.

[0340] Next, in the section with variable segment height (circle 2), the minimum height h1 and maximum height h of the segment are... N When the core diameter C of the electrode assembly is the same, we will explain, with specific examples, how the number of stacked segments changes along the radial direction of the bent surface region F depending on the core diameter C of the electrode assembly.

[0341] The electrode assemblies of Examples 6-1 to 6-6 have a radius of 22 mm, and the radius of the core C is 4 mm. The minimum height h1 of the segment in the height-variable section (circle 2) of segment 61 is the same as 3 mm, and the maximum height h of the segment is the same. N The width was varied from 5 mm to 10 mm in 1 mm increments. Therefore, in the electrode assemblies of Examples 6-1 to 6-6, the width of the variable section height section (circle 2) is 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, and 7 mm, respectively, and the section omitted section (circle 1) is a radius section from 4 mm to 7 mm.

[0342] The electrode assemblies of Examples 7-1 to 7-6 have a radius of 22 mm, and the radius of core C is 2 mm. The minimum height h1 of the segment in the height-variable section (circle 2) of segment 61 is the same as 3 mm, and the maximum height h of the segment is the same.N It was changed in 1 mm units from 5 mm to 10 mm. Therefore, in the electrode assemblies of Examples 7-1 to 7-6, the widths of the height variable sections (circle 2) of the segmented pieces are 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, and 7 mm respectively, and the segmented piece omission section (circle 1) is the same as all the radius sections from a radius of 2 mm to 5 mm.

[0343] FIG. 10e is a graph showing the result of counting the number of stacked segmented pieces measured along the radial direction in the bent surface region F of the positive electrode formed on the upper part of the electrode assemblies according to Examples 6-1 to 6-6 and Examples 7-1 to 7-6. Substantially the same result appears in the bent surface region of the negative electrode.

[0344] In FIG. 10e, graph (a) shows the result of counting the number of stacked segmented pieces measured along the radial direction in the bent surface region F for Examples 6-1 to 6-6, and graph (b) shows the result for Examples 7-1 to 7-6.

[0345] Referring to FIG. 10e, a stacked number uniform section b1 commonly appears in all the examples. The stacked number uniform section b1 is the radius section of the flat region in the graph. When the minimum height h1 of the segmented piece is the same, the length in the radial direction of the stacked number uniform section b1 increases as the maximum height h N of the segmented piece decreases. On the other hand, in the stacked number uniform section b1, the number of stacked segmented pieces increases as the maximum height h N of the segmented piece increases. In the examples, a stacked number decreasing section b2 is confirmed adjacent to the stacked number uniform section b1.

[0346] In the examples, the number of stacked segmented pieces in the stacked number uniform section b1 is all 10 or more. Preferably, the region where the number of stacked segmented pieces is 10 or more can be set as a preferable welding target region.

[0347] In the examples, the uniform layering section b1 begins at the radius point where the variable-height section of the segment (circle 2) begins. In Examples 6-1 to 6-6, the radius at which the variable-height section of the segment (circle 2) begins is 7 mm, and in Examples 7-1 to 7-6, the radius at which the variable-height section of the segment (circle 2) begins is 5 mm.

[0348] Table 6 below shows the calculation results for various parameters for Examples 6-1 to 6-6 and Examples 7-1 to 7-6, including the ratio (e / f) of the length of the uniform layer count section to the length from the radius point where the uniform layer count section begins (7 mm, 5 mm) to the outermost point of the electrode assembly (22 mm), and the ratio (d / f) of the length of the variable-height section of the segment (circle 2) to the length from the radius point where the uniform layer count section begins (7 mm, 5 mm) to the outermost point of the electrode assembly (22 mm).

[0349] [Table 6]

[0350] Referring to Figure 10a and Examples 6-6 and 7-6 in Table 6, the minimum height h1 and maximum height h of the segment in the segment height variable section (circle 2) NThese are identical at 3 mm and 10 mm, respectively. However, the core radius of Example 6-6 is 2 mm larger than that of Example 7-6. Therefore, in Example 6-6, the uniform layer count section (e) and the segment section (f) are 2 mm smaller than in Example 7-6, while the number of layers of segment sections in the uniform layer count section is the same. This result is due to the difference in core radius. From the results shown in Table 6, it can be seen that when the width of the height-variable section of segment sections (circle 2) is the same, the smaller the core radius (a), the smaller the ratio of the height-variable section (circle 2) (d / f), while the ratio of the uniform layer count section (e / f) increases. Referring to Table 6, it can be seen that the number of layers of segment sections is 13 to 26, the ratio of the height-variable section of segment sections (circle 2) (d / f) is 12% to 47%, and the ratio of the length of the uniform layer count section (e / f) is 40% to 76%. Furthermore, the ratio of the segment omission section (circle 1) to the radius (ba) of the electrode assembly excluding the core (c / (ba)) is 15% to 17%. Also, the ratio of the length of the electrode region corresponding to the segment omission section (circle 1) to the total length of the electrode is 6%, the ratio of the length of the electrode region corresponding to the height-variable section (circle 2) to the total length of the electrode is 7% to 32%, and the ratio of the length of the electrode region corresponding to the height-uniform section (circle 3) to the total length of the electrode is 59% to 83%.

[0351] Cylindrical batteries with form factors 1865 and 2170 have an electrode assembly radius of approximately 9mm to 10mm. Therefore, as in the embodiment, it is not possible to secure a radial length of 15mm to 17mm for the segment section (f), and it is not possible to secure a length of approximately 3mm for the segment omission section (circle 1) while simultaneously securing a length of 6mm to 13mm for the uniform stacking section (e) where the number of stacked segments is 10 or more. In conventional cylindrical batteries, if the core radius is designed to be the same as in the embodiment (2mm to 4mm), the radial section in which segment sections can be placed is effectively only 5mm to 8mm. Furthermore, in conventional cylindrical batteries, the length of the electrodes in the winding direction is in the range of 600mm to 980mm. Such short electrode lengths are only about 15% to 24% of the electrode lengths in the embodiment (positive electrode 3948mm, negative electrode 4045mm). Therefore, the numerical ranges for parameters h, i, and j cannot be easily derived from the design specifications of conventional cylindrical batteries.

[0352] Considering the data in Tables 4 to 6 comprehensively, the number of layers of segmental segments in the uniform segmental segmental segment section can be 11 to 26. Also, the ratio (d / f) of the segmental segmental segment with variable height (circle 2) can be 6% to 47%. Also, the ratio (e / f) of the uniform segmental segmental segment can be 31% to 82%. Also, the ratio (c / (ba)) of the length of the segmental segmental segment omitted (circle 1) to the radius of the electrode assembly excluding the core can be 15% to 35%. Also, the ratio of the length of the electrode region corresponding to the segmental segmental segment omitted (circle 1) to the total length of the electrode (length in the winding direction) can be 6% to 20%. Also, the ratio of the length of the electrode region corresponding to the segmental segmental segment with variable height (circle 2) to the total length of the electrode can be 3% to 32%. Also, the ratio of the length of the electrode region corresponding to the segmental segmental segment with uniform height (circle 3) to the total length of the electrode can be 59% to 87%.

[0353] On the other hand, the parameters explained in Tables 4 to 6 are the core radius (a); the electrode assembly radius (b); and the minimum height h1 and maximum height h in the variable section of the segment height (circle 2). N; Change in intercept height Δh per 1 mm increase in radius; may vary depending on design factors including the thickness of the positive electrode, negative electrode, and separation membrane.

[0354] Therefore, the number of layers of subsections in the uniform layering section can be extended from 10 to 35. The ratio (d / f) of the variable-height subsection section (circle 2) can be extended from 1% to 50%. The ratio (e / f) of the uniform layering section can be extended from 30% to 85%. The ratio (c / (ba)) of the length of the subsection omission section (circle 1) to the radius of the electrode assembly excluding the core can be extended from 10% to 40%. The ratio of the length of the electrode region corresponding to the subsection omission section (circle 1) to the total length of the electrode (length in the winding direction) can be extended from 1% to 30%. The ratio of the length of the electrode region corresponding to the variable-height subsection section (circle 2) to the total length of the electrode can be extended from 1% to 40%. The ratio of the length of the electrode region corresponding to the uniform-height subsection section (circle 3) to the total length of the electrode can be extended from 50% to 90%. In the above-described embodiment, the maximum height h of the segment included in the height-variable section (circle 2) and the height-uniform section (circle 3) N The height index N is 2 to 8. For example, referring to Table 4, the height index N for Examples 1-1 and 1-7 is 2 and 8, respectively. However, the height index N can vary depending on the change in height Δh of the segmental section in the radial direction of the electrode assembly. When the radial length of the height-variable section (circle 2) is fixed, a decrease in the change in height Δh of the segmental section increases the height index N, and vice versa is also possible. Preferably, the index N is 2 to 20, and optionally, it can be further extended to 2 to 30.

[0355] In the bent surface regions F formed on the upper and lower parts of the electrode assembly, the uniform layer count section can be used as a welding target region for the current collector.

[0356] Preferably, the welding region of the current collector overlaps with the uniform layering section of the electrode assembly by at least 50% in the radial direction, and a higher overlap ratio is even more preferable.

[0357] Preferably, other regions of the current collector's welding area that do not overlap with the uniform layer count section may overlap with the decreasing layer count section adjacent to the uniform layer count section in the radial direction.

[0358] More preferably, other regions of the current collector's welding area that do not overlap with the uniform layer count section may overlap with regions of the decreasing layer count section where the number of overlapping segments is 10 or more.

[0359] Welding the current collector to a region with 10 or more layers of segmentation is preferable in terms of weld strength and the ability to prevent damage to the separation film and active material layer during welding. This is particularly useful when welding the current collector using a high-power laser with high transmission characteristics.

[0360] When a current collector is welded with a laser to a section with a uniform number of layers, where 10 or more sections are stacked, even if the laser output is increased to improve welding quality, the section with a uniform number of layers absorbs almost all of the laser energy and forms weld beads. This prevents the separation film and active material layer below the bent surface region F from being damaged by the laser.

[0361] Furthermore, because the laser-irradiated area has 10 or more layers of segmented material, welding beads are formed with sufficient volume and thickness. Therefore, sufficient welding strength is ensured, and the resistance at the welding interface can be reduced to a level suitable for rapid charging.

[0362] The laser output during welding of the current collector can be determined by the desired welding strength between the bent surface region F and the current collector. The welding strength increases proportionally to the number of layers of segmentation. This is because the volume of welding beads formed by the laser increases as the number of layers increases. Welding beads are formed as the current collector material and the segmentation material are melted together. Therefore, a larger volume of welding beads results in a stronger bond between the current collector and the bent surface region, and a lower contact resistance at the welding interface.

[0363] Preferably, the welding strength is 2 kgf / cm 2 or more, more preferably 4 kgf / cm 2 or more. The maximum welding strength can vary depending on the output of the laser welding apparatus. As an example, the welding strength is preferably 8 kgf / cm 2 or less, more preferably 6 kgf / cm 2 or less. However, the present invention is not limited thereto.

[0364] When the welding strength satisfies the above numerical range, even if intense vibration is applied to the electrode assembly along the winding axis direction and / or the radial direction, the physical properties of the welding interface do not deteriorate, and since the volume of the welding bead is sufficient, the resistance of the welding interface can also be reduced.

[0365] The output of the laser for satisfying the condition of the welding strength varies depending on the laser apparatus, but can be appropriately adjusted within the range of 250 W to 320 W or within the range of 40% to 100% of the maximum laser output specification provided by the corresponding apparatus.

[0366] The welding strength can be defined as the tensile force per unit area (kgf / cm 2 ) of the current collector when the current collector begins to separate from the bent surface region F. Specifically, after the welding of the current collector is completed, a tensile force is applied to the current collector and its magnitude is gradually increased. When the tensile force exceeds the critical value, the segment begins to separate from the welding interface. At this time, the value obtained by dividing the tensile force applied to the current collector by the area of the current collector corresponds to the welding strength.

[0367] The bent surface region F has segments laminated in a plurality of layers, and according to the above-described embodiment, the number of laminated segments can increase from a minimum of 10 to a maximum of 35.

[0368] The thickness of the positive electrode current collector (foil) constituting the plain portion 43 is 10 μm to 25 μm, and the thickness of the negative electrode current collector (foil) constituting the plain portion 43 may be 5 μm to 20 μm. Therefore, the folded surface region F of the positive electrode may include a region where the total stacking thickness of the segmented pieces is 100 μm to 875 μm. Also, the folded surface region F of the negative electrode may include a region where the total stacking thickness of the segmented pieces is 50 μm to 700 μm.

[0369] Figure 10f is a top view of an electrode assembly showing a uniform layer number section b1 and a decreasing layer number section b2 in the bent surface region F of the segmented sections 61 and 61' according to an embodiment of the present invention.

[0370] Referring to Figure 10f, the region between the two circles shown by the thick solid line corresponds to the folded surface region F of the segment, the region between the two circles shown by the dashed line corresponds to the uniform layer number section b1 where the number of layers of the segment is 10 or more, and the region outside the uniform layer number section b1 corresponds to the decreasing layer number section b2.

[0371] As an example, current collector P c If it is welded to the bent surface region F, the current collector P c Weld pattern W on the surface p This is generated. Weld pattern W p This can be an arrangement of line patterns or dot patterns. Welding pattern W p This corresponds to the welding area and can overlap by 50% or more with the uniform layer number section b1 along the radial direction. Therefore, welding pattern W p A portion of the weld pattern is included in the uniform layer number section b1, and the remaining weld pattern W p This may be included in the layer count reduction section b2 outside the uniform layer count section b1. Of course, in order to maximize welding strength and reduce the resistance of the welding area, the welding pattern W p The entire structure can overlap with the uniform layering interval b1.

[0372] The area of ​​the folded surface region F can be defined as the sum of the area of ​​the uniform layer number section b1 and the area of ​​the decreasing layer number section b2 of the segment. Since the ratio (e / f) of the uniform layer number section b1 is 30% to 85%, preferably 31% to 82%, the ratio of the area of ​​the uniform layer number section b1 to the area of ​​the folded surface region F is 9% (30 2 / 100 2 )~72%(85 2 / 100 2 ), preferably 10% (31 2 / 100 2 )~67%(82 2 / 100 2 ) is possible.

[0373] Preferably, current collector P c The end of the portion that contacts the bent surface region F may cover the end of the segment 61, 61' that is bent towards the core C in the last winding turn of the uniform height section (circle 3). In this case, the segment 61, 61' covers the current collector P c Weld pattern W while pressed down p As a result of the formation of the current collector P c The folded surface region F is strongly bonded to the weld surface region. As a result, the segmented sections 61 and 61' stacked in the winding axis direction are tightly bonded to each other, which reduces the resistance at the welding interface and prevents the segmented sections 61 and 61' from lifting up.

[0374] On the other hand, the bending direction of the segment may be opposite to the direction described above. That is, the segment may be bent from the core side to the outer circumference side. In this case, the pattern in which the height of the segment changes along the winding direction (X-axis direction) may be opposite to that of the embodiment (modified form) described above. For example, the height of the segment may decrease in stages from the core to the outer circumference side. Also, the structure applied to the first part B1 and the structure applied to the second part B3 can be substituted for each other. Preferably, the height change pattern of the segment may be designed so that the height of the segment decreases in stages from the core side to the outer circumference side, and when the segment closest to the outer circumference of the electrode assembly is bent to the outer circumference side, the end of the segment does not protrude outside the outer circumference of the electrode assembly.

[0375] The electrode structure of the above-described embodiment (modified form) can be applied to at least one of a first electrode and a second electrode with different polarities included in a jelly roll type or other type of electrode assembly known in the art. Furthermore, when the electrode structure of the embodiment (modified form) is applied to one of the first electrode and the second electrode, a conventional electrode structure may be applied to the other. Moreover, the electrode structures applied to the first electrode and the second electrode may not be the same, but may be different.

[0376] For example, when the first electrode and the second electrode are the positive and negative electrodes, one of the embodiments (modified forms) may be applied to the first electrode, and a conventional electrode structure (see Figure 1) may be applied to the second electrode.

[0377] As another example, when the first electrode and the second electrode are the positive and negative electrodes, one of the embodiments (modified forms) may be selectively applied to the first electrode, and the other embodiment (modified form) may be selectively applied to the second electrode.

[0378] In one embodiment of the present invention, the positive electrode active material coated on the positive electrode and the negative electrode active material coated on the negative electrode can be any active material known in the industry without limitation.

[0379] For example, the positive electrode active material is a material with the general chemical formula A[A x M y ]O 2+z The compound may contain alkali metal compounds represented as follows: (A contains at least one element from 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; stoichiometric coefficients x, y, and z are selected so that the compound maintains electrical neutrality).

[0380] 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. 1O2-(1-x)Li2M 2 O3(M 1 contains at least one element having an average oxidation state of 3; M 2 contains at least one element having an average oxidation state of 4; 0 ≦ x ≦ 1).

[0381] As 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 so that the compound maintains electrical neutrality), or Li3M2(PO4)3 [M contains at least one element selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Al, Mg and Al].

[0382] Preferably, the positive electrode active material may contain primary particles and / or secondary particles aggregated from primary particles.

[0383] As an example, as the negative electrode active material, a carbon material, a lithium metal or a lithium metal compound, silicon or a silicon compound, tin or a tin compound, etc. can be used. Metal oxides such as TiO2 and SnO2 with a potential of less than 2V can also be used as the negative electrode active material. As the carbon material, both low-crystalline carbon and high-crystalline carbon can be used.​​​As the separation membrane, porous polymer films, such as those made from polyolefin polymers like ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, or ethylene / methacrylate copolymer, can be used alone or in laminated form. As another example, the separation membrane can be made from ordinary porous nonwoven fabrics, such as nonwoven fabrics made from high-melting-point glass fibers or polyethylene terephthalate fibers.

[0385] The separation membrane may include a coating layer of inorganic particles on at least one surface. Alternatively, the separation membrane itself may consist of a coating layer of inorganic particles. The particles constituting the coating layer may have a structure in which they are bound to a binder such that an interstitial volume exists between adjacent particles.

[0386] Inorganic particles may consist of inorganic materials with a dielectric constant of 5 or more. As an unrestricted example, the inorganic particles may be Pb(Zr,Ti)O3(PZT), Pb 1-x La x ZR 1-y Ti y O3(PLZT), PB(Mg3Nb) 2 / 3 It may contain at least one substance selected from the group consisting of O3-PbTiO3(PMN-PT), BaTiO3, hafnia (HfO2), SrTiO3, TiO2, Al2O3, ZrO2, SnO2, CeO2, MgO, CaO, ZnO, and Y2O3.

[0387] The structure of an electrode assembly according to one embodiment of the present invention will be described in detail below.

[0388] Figure 11 is a cross-sectional view of a jelly roll-type electrode assembly 80, in which the electrodes 40 of the first embodiment are applied as the first electrode (positive electrode) and the second electrode (negative electrode), cut along the Y-axis direction (winding axis direction).

[0389] The electrode assembly 80 can be manufactured by the winding method described with reference to Figure 2. For the sake of explanation, the protruding structures of the first blank portion 43a and the second blank portion 43b extending to the outside of the separation membrane are shown in detail, while the illustration of the winding structure of the first electrode, the second electrode, and the separation membrane is omitted. The first blank portion 43a protruding upward extends from the first electrode, and the second blank portion 43b protruding downward extends from the second electrode.

[0390] The patterns of how the heights of the first blank section 43a and the second blank section 43b change are schematically shown. That is, the height of the blank section can change irregularly depending on the cutting position of the cross section. For example, if the sides of the trapezoidal subsections 61 and 61' or the cutting groove 63 are cut, the height of the blank section in the cross section will be lower than the height H of the subsections 61 and 61'. Therefore, the height of the blank section shown in the drawing of the cross section of the electrode assembly should be understood to correspond to the average height of the blank section included in each winding turn (H in Figures 7b and 8b).

[0391] Referring to Figure 11, the first blank portion 43a includes a first portion B1 adjacent to the core of the electrode assembly 80, a second portion B3 adjacent to the outer peripheral surface of the electrode assembly 80, and a third portion B2 interposed between the first portion B1 and the second portion B3.

[0392] The height (length in the Y-axis direction) of the second section B3 is relatively lower than the height of the third section B2. Therefore, it is possible to prevent the phenomenon of the beading portion of the battery housing coming into contact with the second section B3 and causing an internal short circuit during the process in which the beading portion is pressed against the second section B3.

[0393] The second blank portion 43b has the same structure as the first blank portion 43a. In one modified form, the second blank portion 43b may have a conventional electrode structure or an electrode structure of another embodiment (modified form).

[0394] The ends 81 of the first blank portion 43a and the second blank portion 43b can be bent radially from the electrode assembly 80, for example, from the outer circumference to the core. In this case, the second portion B3 does not need to be bent substantially.

[0395] Figure 12 is a cross-sectional view of a jelly roll-type electrode assembly 90, in which the electrodes 45 of the second embodiment are applied to the first electrode (positive electrode) and the second electrode (negative electrode), cut along the Y-axis direction (winding axis direction).

[0396] Referring to Figure 12, the first blank portion 43a of the first electrode includes a first portion B1 adjacent to the core of the electrode assembly 90, a second portion B3 adjacent to the outer peripheral surface of the electrode assembly 90, and a third portion B2 interposed between the first portion B1 and the second portion B3.

[0397] The height of the second section B3 is relatively lower than the height of the third section B2, and decreases gradually or in stages from the core side to the outer circumference. Therefore, it is possible to prevent the phenomenon of the beading portion of the battery housing coming into contact with the second section B3 and causing an internal short circuit during the process in which the beading portion is pressed near the second section B3.

[0398] The second blank portion 43b has the same structure as the first blank portion 43a. In one modified form, the second blank portion 43b may have a conventional electrode structure or an electrode structure of another embodiment (modified form).

[0399] The ends 91 of the first blank portion 43a and the second blank portion 43b can be bent radially from the electrode assembly 90, for example, from the outer circumference to the core. In this case, the outermost part 92 of the second portion B3 does not need to be bent substantially.

[0400] Figure 13 is a cross-sectional view of a jelly roll-type electrode assembly 100, cut along the Y-axis direction (winding axis direction), in which one of the electrodes 50, 60, or 70 of the third to fifth embodiments (variations thereof) is applied as the first electrode (positive electrode) and the second electrode (negative electrode).

[0401] Referring to Figure 13, the plain portion 43a of the first electrode includes a first portion B1 adjacent to the core of the electrode assembly 100, a second portion B3 adjacent to the outer peripheral surface of the electrode assembly 100, and a third portion B2 interposed between the first portion B1 and the second portion B3.

[0402] The height of the first part B1 is relatively lower than the height of the third part B2. Also, in the third part B2, the fold length of the innermost plain section 43a is the same as or shorter than the radial length R of the first part B1. The fold length H corresponds to the distance from the point where the plain section 43a is folded to the upper end of the plain section 43a. In the modified example, the fold length H may be smaller than the sum of the radial length R of the first part B1 and 10% of the radius of the core 102.

[0403] Therefore, even if the third part B2 is bent, more than 90% of the diameter of the core 102 of the electrode assembly 100 remains open to the outside. The core 102 is a cavity at the center of the electrode assembly 100. If the core 102 is not blocked, the electrolyte injection process is not hindered, and the efficiency of electrolyte injection is improved. In addition, a welding jig can be inserted through the core 102 to facilitate the welding process between the negative electrode (or positive electrode) side current collector and the battery housing (or terminal).

[0404] The height of the second section B3 is relatively lower than the height of the third section B2. Therefore, it is possible to prevent the phenomenon of the beading portion of the battery housing coming into contact with the second section B3 and causing an internal short circuit during the process in which the beading portion is pressed against the second section B3.

[0405] In one modified form, the height of the second part B3 may decrease gradually or in steps, unlike in the illustration in Figure 13. Also, in Figure 13, the height of the third part B2 is equal in a portion of the outer periphery, but the height of the third part B2 may increase gradually or in steps from the boundary between the first part B1 and the third part B2 to the boundary between the third part B2 and the second part B3. When the third part B2 is divided into multiple subsections, the section in which the height of the plain area 43a changes corresponds to the section with variable height (circle 2 in Figure 10a).

[0406] The second blank portion 43b has the same structure as the first blank portion 43a. In one modified form, the second blank portion 43b may have a conventional electrode structure or an electrode structure of another embodiment (modified form).

[0407] The ends 101 of the first blank portion 43a and the second blank portion 43b can be bent radially from the electrode assembly 100, for example, from the outer circumference to the core. In this case, the first portion B1 and the second portion B3 are not substantially bent.

[0408] When the third section B2 includes multiple subsections, the bending stress is relieved, which prevents the plain section 43a near the bending point from tearing or becoming abnormally deformed. Furthermore, when the width and / or height and / or spacing pitch of the subsections are adjusted within the numerical range of the above-described embodiment, the subsections overlap in sufficient quantities to ensure sufficient welding strength while being bent toward the core, and do not form any gaps in the bent surface region.

[0409] Figure 14 is a cross-sectional view of an electrode assembly 110 according to yet another embodiment of the present invention, cut along the Y-axis direction (winding axis direction).

[0410] Referring to Figure 14, the electrode assembly 110 is substantially identical to the electrode assembly 100 in Figure 13, except that the height of the second part B3 is substantially the same as the height of the outermost part B2.

[0411] The second part B3 may include multiple segments. The configuration of the multiple segments is substantially the same as that of the fourth and fifth embodiments (modified forms) relating to the electrodes.

[0412] In the electrode assembly 110, the height of the first portion B1 is relatively lower than the height of the third portion B2. Also, the fold length H of the plain portion located on the innermost side of the third portion B2 is the same as or shorter than the radial length R of the first portion B1. Preferably, the first portion B1 may be a segment-omitted section without segment segments (circle 1 in Figure 10a). In a modified example, the fold length H may be smaller than the sum of the radial length R of the first portion B1 and 10% of the radius of the core 112.

[0413] Therefore, even if the third portion B2 is bent, more than 90% of the diameter of the core 112 of the electrode assembly 110 remains open to the outside. If the core 112 is not blocked, the electrolyte injection process is not hindered, and the efficiency of electrolyte injection is improved. Furthermore, a welding jig can be inserted through the core 112 to facilitate the welding process between the negative electrode (or positive electrode) current collector and the battery housing (or terminal).

[0414] In one modified form, a structure in which the height of the third portion B2 gradually or stepwise increases from the core side toward the outer periphery can be extended to the second portion B3. In this case, the height of the plain portion 43a can gradually or stepwise increase from the boundary between the first portion B1 and the third portion B2 toward the outermost surface of the electrode assembly 110.

[0415] The second blank portion 43b has the same structure as the first blank portion 43a. In one modified form, the second blank portion 43b may have a conventional electrode structure or an electrode structure of another embodiment (modified form).

[0416] The ends 111 of the first blank portion 43a and the second blank portion 43b can be bent radially from the electrode assembly 110, for example, from the outer circumference to the core. In this case, the first portion B1 is not substantially bent.

[0417] When the third part B2 and the second part B3 include multiple subsections, the bending stress is relieved, which prevents the plain sections 43a and 43b near the bending point from tearing or becoming abnormally deformed. Furthermore, when the width and / or height and / or spacing pitch of the subsections are adjusted within the numerical range of the above-described embodiment, the subsections overlap in sufficient quantities to ensure sufficient welding strength while being bent toward the core, and do not form any gaps in the bent surface region.

[0418] Figure 15 is a cross-sectional view of an electrode assembly 120 according to yet another embodiment of the present invention, cut along the Y-axis direction (winding axis direction).

[0419] Referring to Figure 15, the electrode assembly 120 differs from the electrode assembly 100 in Figure 13 only in that the height of the third portion B2 has a pattern in which it gradually or stepwise increases and then decreases, while the other configurations are substantially the same. The radial section in which the height of the third portion B2 changes can be considered as the variable height section of the segment (circle 2 in Figure 10a). In this case as well, the variable height section of the segment can be designed such that in the bent surface region F formed as the third portion B2 is bent, a uniform stacking number section in which the number of stacked segments is 10 or more appears within the preferred numerical range described above.

[0420] Such height changes in the third section B2 can be achieved by adjusting the height of the staircase pattern (see Figure 6) or the segment (see Figure 7a or Figure 8a) included in the third section B2.

[0421] In the electrode assembly 120, the height of the first part B1 is relatively lower than the height of the third part B2. Also, the fold length H of the plain section located on the innermost side of the third part B2 is the same as or shorter than the radial length R of the first part B1. The section corresponding to the first part B1 corresponds to the section without a subsection (circle 1 in Figure 10a). In the modified example, the fold length H may be smaller than the sum of the radial length R of the first part B1 and 10% of the core 102 radius.

[0422] Therefore, even if the third portion B2 is bent toward the core, the core 122 of the electrode assembly 120 remains open to the outside by more than 90% of its diameter. If the core 122 is not blocked, the electrolyte injection process is not hindered, and the efficiency of electrolyte injection is improved. Furthermore, a welding jig can be inserted through the core 122 to facilitate the welding process between the negative electrode (or positive electrode) current collector and the battery housing (or terminal).

[0423] Furthermore, the height of the second portion B3 is relatively lower than the height of the third portion B2, and preferably, no segment is formed in the second portion B3. Therefore, it is possible to prevent the phenomenon of an internal short circuit occurring when the beading portion of the battery housing is pressed against the second portion B3 and the beading portion and the second portion B3 come into contact with each other. In one modified example, the height of the second portion B3 may decrease gradually or in steps toward the outer circumference.

[0424] The second blank portion 43b has the same structure as the first blank portion 43a. In a modified example, the second blank portion 43b may have a conventional electrode structure or an electrode structure of another embodiment (modified form).

[0425] The ends 121 of the first blank portion 43a and the second blank portion 43b can be bent from the outer circumference side of the electrode assembly 120 toward the core side. In this case, the first portion B1 and the second portion B3 are not substantially bent.

[0426] When the third section B2 includes multiple subsections, the bending stress is relieved, which prevents the plain sections 43a and 43b from tearing or becoming abnormally deformed. Furthermore, when the width and / or height and / or spacing pitch of the subsections are adjusted within the numerical range of the above-described embodiment, the subsections overlap in sufficient quantities to ensure sufficient welding strength while being bent toward the core, and do not form any gaps in the bent surface region.

[0427] Figure 16 is a cross-sectional view of an electrode assembly 130 according to yet another embodiment of the present invention, cut along the Y-axis direction (winding axis direction).

[0428] Referring to Figure 16, the electrode assembly 130 differs from the electrode assembly 120 in Figure 15 in that the height of the second portion B3 has a pattern in which it gradually or stepwise decreases from the boundary point between the second portion B3 and the third portion B2 toward the outermost surface of the electrode assembly 130, while the other components are substantially the same.

[0429] Such a change in the height of the second section B3 can be achieved by extending the staircase pattern included in the third section B2 (see Figure 6) to the second section B3, and by gradually or stepwise decreasing the height of the pattern toward the outer periphery. In other modifications, the change in the height of the second section B3 can also be achieved by extending the segment structure of the third section B2 to the second section B3, and by gradually or stepwise decreasing the height of the segment toward the outer periphery.

[0430] In the electrode assembly 130, the height of the first part B1 is relatively lower than the height of the third part B2. Also, the fold length H of the plain section located on the innermost side of the third part B2 is the same as or shorter than the radial length R of the first part B1. The first part B1 corresponds to a section without a subsection (circle 1 in Figure 10a). In the modified example, the fold length H may be smaller than the sum of the radial length R of the first part B1 and 10% of the core 102 radius.

[0431] Therefore, even if the third portion B2 is bent toward the core, more than 90% of the diameter of the core 132 of the electrode assembly 130 remains open to the outside. If the core 132 is not blocked, the electrolyte injection process is not hindered, and the efficiency of electrolyte injection is improved. Furthermore, a welding jig can be inserted through the core 132 to facilitate the welding process between the negative electrode (or positive electrode) side current collector and the battery housing (or terminal).

[0432] The second blank portion 43b has the same structure as the first blank portion 43a. In one modified form, the second blank portion 43b may have a conventional electrode structure or an electrode structure of another embodiment (modified form).

[0433] The ends 131 of the first blank portion 43a and the second blank portion 43b can be bent from the outer circumference side of the electrode assembly 130 toward the core side. In this case, the first portion B1 is not substantially bent.

[0434] When the third part B2 and the second part B3 include multiple subsections, the bending stress is relieved, which prevents the plain sections 43a and 43b near the bending point from tearing or becoming abnormally deformed. Furthermore, when the width and / or height and / or spacing pitch of the subsections are adjusted within the numerical range of the above-described embodiment, the subsections overlap in sufficient quantities to ensure sufficient welding strength while being bent toward the core, and do not form any gaps in the bent surface region.

[0435] On the other hand, in the above-described embodiment (modified form), the ends of the first blank portion 43a and the second blank portion 43b can be bent from the core side to the outer circumference. In this case, it is preferable that the second portion B3 is designed as a section without segmentation segments (circle 1 in Figure 10a) and is not bent to the outer circumference. Also, the radial width of the second portion B3 may be the same as or greater than the length to which the outermost blank portion (or segmentation segment) of the third portion B2 is bent. This prevents the end of the bent portion from protruding beyond the outer surface of the electrode assembly toward the inner surface of the battery housing when the outermost blank portion (or segmentation segment) of the third portion B2 is bent toward the outer circumference. Furthermore, the pattern of change in the segmentation segment structure may be the opposite of that in the above-described embodiment (modified form). For example, the height of the segmentation segment may increase stepwise or gradually from the core side toward the outer circumference. In other words, by arranging sections with omitted segments (circle 1 in Figure 10a), sections with variable segment height (circle 2 in Figure 10a), and sections with uniform segment height (circle 3 in Figure 10a) in order from the outer circumference to the core of the electrode assembly, it is possible to ensure that sections with a uniform number of layers, where the number of layered segments is 10 or more, appear in the folded surface region within a preferred numerical range.

[0436] The diverse electrode assembly structures according to embodiments of the present invention are applicable to cylindrical batteries.

[0437] Preferably, the cylindrical battery may be a cylindrical battery with a form factor ratio (defined as the ratio of the diameter to the height of the cylindrical battery, i.e., the ratio of height (H) to relative diameter (Φ)) greater than approximately 0.4. Here, the form factor refers to the values ​​indicating the diameter and height of the cylindrical battery.

[0438] Preferably, the diameter of the cylindrical battery may be 40 mm to 50 mm, and the height may be 60 mm to 130 mm. The form factor of a cylindrical battery according to one embodiment may be, for example, 46110, 4875, 48110, 4880, or 4680. In the numerical representation of the form factor, the first two digits indicate the diameter of the battery, and the remaining digits indicate the height of the battery.

[0439] When an electrode assembly with a tabless structure is applied to a cylindrical battery with a form factor ratio exceeding 0.4, the stress applied radially when bending the plain section is large, making the plain section prone to tearing. Furthermore, when welding a current collector to the bent surface region of the plain section, the number of layers of the plain section in the bent surface region must be sufficiently increased in order to ensure sufficient welding strength and reduce resistance. These requirements can be met by the electrode and electrode assembly according to an embodiment (modified form) of the present invention.

[0440] A battery according to one embodiment of the present invention may be a cylindrical battery that is substantially cylindrical in shape, with a diameter of approximately 46 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0441] A battery according to another embodiment may be a cylindrical battery that is substantially cylindrical in shape, with a diameter of approximately 48 mm, a height of approximately 75 mm, and a form factor ratio of 0.640.

[0442] Furthermore, another embodiment of the battery may be a cylindrical battery that is substantially cylindrical in shape, with a diameter of approximately 48 mm, a height of approximately 110 mm, and a form factor ratio of 0.436.

[0443] Furthermore, a battery according to another embodiment may be a cylindrical battery that is substantially cylindrical in shape, with a diameter of approximately 48 mm, a height of approximately 80 mm, and a form factor ratio of 0.600.

[0444] Furthermore, a battery according to another embodiment may be a cylindrical battery that is substantially cylindrical in shape, with a diameter of approximately 46 mm, a height of approximately 80 mm, and a form factor ratio of 0.575.

[0445] Traditionally, batteries with a form factor ratio of approximately 0.4 or less have been used. For example, 1865 batteries and 2170 batteries have been used. In the case of an 1865 battery, the diameter is approximately 18mm, the height is approximately 65mm, and the form factor ratio is 0.277. In the case of a 2170 battery, the diameter is approximately 21mm, the height is approximately 70mm, and the form factor ratio is 0.300.

[0446] The following describes in detail a cylindrical battery according to one embodiment of the present invention.

[0447] Figure 17 is a cross-sectional view of a cylindrical battery 140 according to one embodiment of the present invention, cut along the Y-axis.

[0448] Referring to Figure 17, a cylindrical battery 140 according to one embodiment of the present invention includes an electrode assembly 141 comprising a first electrode, a separator membrane, and a second electrode, a battery housing 142 housing the electrode assembly 141, and a seal 143 sealing the open end of the battery housing 142.

[0449] The battery housing 142 is a cylindrical container with an opening formed at the top. The battery housing 142 is made of a conductive metallic material such as aluminum, steel, or stainless steel. A nickel coating layer may be formed on the surface of the battery housing 142. The battery housing 142 houses the electrode assembly 141 in its inner space through the upper opening, and also houses the electrolyte together with it.

[0450] Electrolytes are, A + B - It can be a salt with a structure like this. Here, A + Li + kaNa + , K + It contains alkali metal cations such as, or ions consisting of combinations thereof. And, B - is, F - Cl - , Br - , I - NO3 - , N(CN)2 - BF4 - ClO4 - AlO4 - AlCl4 - PF6 - SbF6 - AsF6 - BF2C2O4 - BC4O8 - (CF3)2PF4 - (CF3)3PF3 - (CF3)4PF2 - (CF3)5PF - (CF3)6P - CF3SO3 - , C4F9SO3 - CF3CF2SO3 - (CF3SO2)2N - , (FSO2)2N - CF3CF2(CF3)2CO - (CF3SO2) 2CH - (SF5)3C - (CF3SO2)3C - CF3(CF2)7SO3 - CF3CO2- CH3CO2 - SCN - and (CF3CF2SO2)2N - It contains one or more anions selected from the group consisting of the following.

[0451] Furthermore, electrolytes may be used after being dissolved in an organic solvent. Suitable organic solvents include propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), γ-butyrolactone, or mixtures thereof.

[0452] The electrode assembly 141 may have a jelly-roll structure, but the present invention is not limited thereto. As shown in Figure 2, the electrode assembly 141 can be manufactured by winding a laminate formed by stacking a lower separation membrane, a first electrode, an upper separation membrane, and a second electrode in order at least once, with the laminate being wound around a winding shaft C.

[0453] The first electrode and the second electrode have different polarities. That is, if one has positive polarity, the other has negative polarity. At least one of the first electrode and the second electrode may have an electrode structure according to the embodiment (modified form) described above. The other of the first electrode and the second electrode may have a conventional electrode structure or an electrode structure according to the embodiment (modified form). The electrode assembly 141 is not limited to one electrode pair, but may have two or more.

[0454] The first blank portion 146a of the first electrode and the second blank portion 146b of the second electrode protrude from the upper and lower parts of the electrode assembly 141, respectively. The first electrode has the electrode structure of the first embodiment (modified form). Therefore, the height of the second portion B3 of the first blank portion 146a is lower than the height of the blank portions of the other parts. The second portion B3 is separated from the inner circumferential surface of the battery housing 142, particularly the beading portion 147, by a predetermined distance. Therefore, since the second portion B3 of the first electrode does not come into contact with the battery housing 142 which is electrically connected to the second electrode, an internal short circuit of the cylindrical battery 140 is prevented.

[0455] The second blank portion 146b of the second electrode may have the same structure as the first blank portion 146a. In other modified forms, the second blank portion 146b may selectively have the structure of the blank portion of the electrode according to the embodiment (modified form).

[0456] The sealing body 143 may include a plate-shaped cap 143a, a first gasket 143b that provides airtightness and insulation between the cap 143a and the battery housing 142, and a connecting plate 143c that is electrically and mechanically coupled to the cap 143a.

[0457] The cap 143a is a component made of a conductive metal material and covers the upper opening of the battery housing 142. The cap 143a is electrically connected to the first blank portion 146a of the first electrode and electrically insulated from the battery housing 142 through the first gasket 143b. Thus, the cap 143a can function as the first electrode terminal (e.g., the positive electrode) of the cylindrical battery 140.

[0458] The cap 143a is placed on a beading portion 147 formed on the battery housing 142 and secured by a crimping portion 148. A first gasket 143b may be interposed between the cap 143a and the crimping portion 148 to ensure airtightness of the battery housing 142 and to provide electrical insulation between the battery housing 142 and the cap 143a. The cap 143a may have a projection 143d that protrudes upward from its center.

[0459] The battery housing 142 is electrically connected to the second blank portion 146b of the second electrode. Therefore, the battery housing 142 has the same polarity as the second electrode. If the second electrode has negative polarity, then the battery housing 142 also has negative polarity.

[0460] The battery housing 142 is provided with a beading portion 147 and a crimping portion 148 at its upper end. The beading portion 147 is formed by pressing around the outer circumferential surface of the battery housing 142. The beading portion 147 prevents the electrode assembly 141 housed inside the battery housing 142 from coming out of the upper end opening of the battery housing 142 and can function as a support portion on which the seal 143 is placed.

[0461] The inner surface of the beading portion 147 is separated from the second portion B3 of the first electrode by a predetermined distance. More specifically, the lower end of the inner surface of the beading portion 147 is separated from the second portion B3 of the first electrode by a predetermined distance. Furthermore, because the second portion B3 is low in height, it is not substantially affected when the battery housing 142 is pushed in from the outside to form the beading portion 147. Therefore, the second portion B3 is not compressed by other components such as the beading portion 147, thereby preventing partial deformation of the electrode assembly 141 and preventing internal short circuits in the cylindrical battery 140.

[0462] Preferably, if the indentation depth of the beading portion 147 is D1 and the radial length from the inner circumferential surface of the battery housing 142 to the boundary point between the second portion B3 and the third portion B2 is D2, then the relationship "D1 ≤ D2" may be satisfied. In this case, when the battery housing 142 is pressed in to form the beading portion 147, damage to the second portion B3 is substantially prevented.

[0463] The crimping portion 148 is formed on the upper part of the beading portion 147. The crimping portion 148 has a shape that extends and bends to enclose the outer circumferential surface of the cap 143a, which is positioned on the beading portion 147, and a portion of the upper surface of the cap 143a.

[0464] The cylindrical battery 140 may further include a first current collector 144 and / or a second current collector 145 and / or an insulator 146.

[0465] The first current collector 144 is coupled to the upper part of the electrode assembly 141. The first current collector 144 is made of a conductive metallic material such as aluminum, copper, steel, or nickel, and is electrically connected to the first blank portion 146a of the first electrode. The electrical connection may be made by welding. A lead 149 may be connected to the first current collector 144. The lead 149 may extend above the electrode assembly 141 and be coupled to the coupling plate 143c, or it may be directly coupled to the lower surface of the cap 143a. The lead 149 may be coupled to other components by welding.

[0466] Preferably, the first current collector 144 can be formed integrally with the lead 149. In this case, the lead 149 may have a long plate shape extending outward from near the center of the first current collector 144.

[0467] The first current collector 144 may have a plurality of radially arranged protrusions (not shown) on its lower surface. If radial protrusions are provided, the first current collector 144 can be pressed against the protrusions to press the first blank portion 146a of the first electrode into the protrusions.

[0468] The first current collector 144 is coupled to the end of the first blank portion 146a. The coupling between the first blank portion 146a and the first current collector 144 can be performed, for example, by laser welding. Laser welding can be performed in a manner that partially melts the base material of the first current collector 144. In a modified example, the welding between the first current collector 144 and the first blank portion 146a can be performed with solder interposed. In this case, the solder may have a lower melting point than the first current collector 144 and the first blank portion 146a. Laser welding can be replaced by resistance welding, ultrasonic welding, spot welding, etc.

[0469] A second current collector 145 may be coupled to the lower surface of the electrode assembly 141. One side of the second current collector 145 may be welded to the second blank section 146b, and the other side may be welded to the inner bottom surface of the battery housing 142. The coupling structure between the second current collector 145 and the second blank section 146b may be substantially the same as the coupling structure between the first current collector 144 and the first blank section 146a.

[0470] The plain sections 146a and 146b are not limited to the illustrated structures. Therefore, the plain sections 146a and 146b may selectively have not only the conventional plain section structure but also the plain section structure of the electrode according to the embodiment (modified form).

[0471] The insulator 146 can cover the first current collector 144. By covering the upper surface of the first current collector 144 with the insulator 146, direct contact between the first current collector 144 and the inner surface of the battery housing 142 can be prevented.

[0472] The insulator 146 is provided with a lead hole 151 through which a lead 149 extending upward from the first current collector 144 is drawn out. The lead 149 is drawn out upward through the lead hole 151 and coupled to the lower surface of the connecting plate 143c or the lower surface of the cap 143a.

[0473] The peripheral region of the insulator 146 is interposed between the first current collector 144 and the beading portion 147, and can fix the connection between the electrode assembly 141 and the first current collector 144. As a result, the movement of the connection between the electrode assembly 141 and the first current collector 144 in the winding axis direction (Y axis direction) of the cylindrical battery 140 is restricted, and the assembly stability of the cylindrical battery 140 can be improved.

[0474] The insulator 146 may consist of an insulating polymer resin. For example, the insulator 146 may consist of polyethylene, polypropylene, polyimide, or polybutylene terephthalate.

[0475] The battery housing 142 may further include a vent portion 152 formed on its lower surface. The vent portion 152 corresponds to an area on the lower surface of the battery housing 142 that is thinner than the surrounding area. The vent portion 152 is structurally weaker than the surrounding area. Therefore, if an abnormality occurs in the cylindrical battery 140 and the internal pressure increases above a certain level, the vent portion 152 may rupture, and the gas generated inside the battery housing 142 may be discharged to the outside. The internal pressure at which the vent portion 152 ruptures is approximately 15 kgf / cm². 2 ~35 kgf / cm² 2 It is possible.

[0476] The vent portion 152 may be formed continuously or discontinuously in a circular pattern on the lower surface of the battery housing 142. In a modified form, the vent portion 152 may be formed in a linear pattern or other patterns.

[0477] Figure 18 is a cross-sectional view of a cylindrical battery 150 according to another embodiment of the present invention, cut along the Y-axis.

[0478] Referring to Figure 18, the cylindrical battery 150 is substantially identical to the cylindrical battery 140 in Figure 17, except that the electrode structure of the second embodiment (modified form) is adopted for the first blank portion 146a of the first electrode.

[0479] Referring to Figure 18, the first blank portion 146a of the first electrode may be in a form in which the height of the second portion B3 gradually or in steps toward the inner surface of the battery housing 142. Preferably, a virtual line connecting the uppermost ends of the second portion B3 may have the same or similar shape as the inner surface of the beading portion 147.

[0480] The second portion B3 forms an inclined surface. Therefore, when the battery housing 142 is pressed in to form the beading portion 147, the second portion B3 can be prevented from being compressed and damaged by the beading portion 147. In addition, the phenomenon of the second portion B3 coming into contact with the battery housing 142 of the opposite polarity and causing an internal short circuit can be suppressed.

[0481] The other components of the cylindrical battery 150 are substantially the same as those of the embodiment (modified form) described above.

[0482] The plain sections 146a and 146b are not limited to the illustrated structures. Therefore, the plain sections 146a and 146b may selectively have not only the conventional plain section structure but also the plain section structure of the electrode according to the embodiment (modified form).

[0483] Figure 19 is a cross-sectional view of a cylindrical battery 160 according to yet another embodiment of the present invention, cut along the Y-axis.

[0484] Referring to Figure 19, the cylindrical battery 160 is substantially identical in configuration to the cylindrical batteries 140 and 150 described above, except that the lead 149 connected to the first current collector 144 is directly connected to the cap 143a of the sealing body 143 through the lead hole 151 of the insulator 146, and the insulator 146 and the first current collector 144 are in close contact with the lower surface of the cap 143a.

[0485] In the cylindrical battery 160, the diameter of the first current collector 144 and the outermost diameter of the third portion B2 are smaller than the minimum inner diameter of the battery housing 142. Also, the diameter of the first current collector 144 may be the same as or larger than the outermost diameter of the third portion B2.

[0486] Specifically, the minimum inner diameter of the battery housing 142 may correspond to the inner diameter of the battery housing 142 at the location where the beading portion 147 is formed. In this case, the outermost diameters of the first current collector 144 and the third portion B2 are smaller than the inner diameter of the battery housing 142 at the location where the beading portion 147 is formed. Also, the diameter of the first current collector 144 may be the same as or larger than the outermost diameter of the third portion B2. The peripheral region of the insulator 146 is interposed between the second portion B3 and the beading portion 147 in a folded state at the bottom, and can fix the combined body of the electrode assembly 141 and the first current collector 144.

[0487] Preferably, the insulator 146 includes a portion that covers the second portion B3 and a portion that covers the first current collector 144, and the portion connecting these two portions may have a shape that is bent together in accordance with the bend shape of the beading portion 147. The insulator 146 can insulate the second portion B3 from the inner surface of the beading portion 147, and at the same time insulate the first current collector 144 from the inner surface of the beading portion 147.

[0488] The first current collector 144 may be positioned higher than the lower end of the beading portion 147 and may be coupled to the first portion B1 and the third portion B2. In this case, the indentation depth D1 of the beading portion 147 is less than or equal to the distance D2 from the inner circumferential surface of the battery housing 142 to the boundary between the second portion B3 and the third portion B2. Therefore, the first portion B1 and the third portion B2, and the first current collector 144 coupled to them, may be positioned higher than the lower end of the beading portion 147. The lower end of the beading portion 147 refers to the bending point B between the portion of the battery housing 142 in which the electrode assembly 141 is housed and the beading portion 147.

[0489] Since the first part B1 and the third part B2 occupy the radially inner space of the beading portion 147, the empty space between the electrode assembly 141 and the cap 143a is minimized. Furthermore, the connecting plate 143c, which was located in the empty space between the electrode assembly 141 and the cap 143a, is omitted. Therefore, the lead 149 of the first current collector 144 can be directly connected to the lower surface of the cap 143a. With this structure, the empty space within the battery is reduced, and the energy density can be maximized by the amount of this reduced empty space.

[0490] In the cylindrical battery 160, the first current collector 144 and the second current collector 145 can be welded to the ends of the first blank portion 146a and the second blank portion 146b, respectively, as in the embodiment described above.

[0491] The plain sections 146a and 146b are not limited to the illustrated structures. Therefore, the plain sections 146a and 146b may selectively have not only the conventional plain section structure but also the plain section structure of the electrode according to the embodiment (modified form).

[0492] Figure 20 is a cross-sectional view of a cylindrical battery 170 according to yet another embodiment of the present invention, cut along the Y-axis.

[0493] Referring to Figure 20, the cylindrical battery 170 differs from the cylindrical battery 140 shown in Figure 17 in that the structure of the electrode assembly is substantially the same, and other structural changes have been made excluding the electrode assembly.

[0494] Specifically, the cylindrical battery 170 includes a battery housing 171 through which terminals 172 are inserted. Terminals 172 are mounted through through holes formed in the closed surface (top surface in the drawing) of the battery housing 171. Terminals 172 are reveting the through holes in the battery housing 171 with a second gasket 173 made of an insulating material interposed between them. Terminals 172 are exposed outward in the direction opposite to the direction of gravity.

[0495] The terminal 172 includes a terminal exposure portion 172a and a terminal insertion portion 172b. The terminal exposure portion 172a is exposed to the outside of the closed surface of the battery housing 171. The terminal exposure portion 172a may be located approximately in the center of the closed surface of the battery housing 171. The maximum diameter of the terminal exposure portion 172a may be formed to be larger than the maximum diameter of the through hole formed in the battery housing 171. The terminal insertion portion 172b may penetrate approximately in the center of the closed surface of the battery housing 171 and be electrically connected to the first blank portion 146a of the first electrode. The bottom edge of the terminal insertion portion 172b may be riveted onto the inner surface of the battery housing 171. That is, the bottom edge of the terminal insertion portion 172b may have a curved shape toward the inner surface of the battery housing 171. Inside the bottom edge of the terminal insertion portion 172b is a flat portion 172c. The maximum diameter of the bottom of the riveted terminal insertion portion 172b may be even larger than the maximum diameter of the through-hole in the battery housing 171.

[0496] The flat portion 172c of the terminal insertion portion 172b can be welded to the central portion of the first current collector 144, which is connected to the first blank portion 146a of the first electrode. Laser welding is preferred as the welding method, but other welding methods such as ultrasonic welding can be used as alternatives.

[0497] An insulator 174 made of an insulating material may be interposed between the first current collector 144 and the inner surface of the battery housing 171. The insulator 174 covers the upper part of the first current collector 144 and the upper peripheral portion of the electrode assembly 141. This prevents the second portion B3 of the electrode assembly 141 from coming into contact with the inner surface of the battery housing 171, which has opposite polarity, and causing a short circuit.

[0498] The thickness of the insulator 174 corresponds to or is slightly greater than the distance between the upper surface of the first current collector 144 and the inner surface of the closing portion of the battery housing 171. Therefore, the insulator 174 can come into contact with the upper surface of the first current collector 144 and the inner surface of the closing portion of the battery housing 171.

[0499] The terminal insertion portion 172b of the terminal 172 can be welded to the first current collector 144 through a through-hole in the insulator 174. The diameter of the through-hole formed in the insulator 174 may be larger than the diameter of the rivet portion at the bottom of the terminal insertion portion 172b. Preferably, the through-hole may expose the bottom of the terminal insertion portion 172b and the second gasket 173.

[0500] The second gasket 173 is interposed between the battery housing 171 and the terminal 172, preventing the battery housing 171 and the terminal 172, which have opposite polarities, from making electrical contact. This allows the upper surface of the battery housing 171, which has a substantially flat shape, to function as the second electrode terminal (e.g., the negative electrode) of the cylindrical battery 170.

[0501] The second gasket 173 includes a gasket exposed portion 173a and a gasket inserted portion 173b. The gasket exposed portion 173a is interposed between the terminal exposed portion 172a of the terminal 172 and the battery housing 171. The gasket inserted portion 173b is interposed between the terminal inserted portion 172b of the terminal 172 and the battery housing 171. The gasket inserted portion 173b can be deformed together with the terminal inserted portion 172b during reveting to make it tightly adhere to the inner surface of the battery housing 171. The second gasket 173 may be made of, for example, an insulating polymer resin.

[0502] The gasket exposed portion 173a of the second gasket 173 may have a shape that extends to cover the outer circumferential surface of the terminal exposed portion 172a of the terminal 172. When the second gasket 173 covers the outer circumferential surface of the terminal 172, it is possible to prevent short circuits from occurring during the process of coupling electrical connection components such as busbars to the upper surface of the battery housing 171 and / or the terminal 172. Although not shown, the gasket exposed portion 173a may have a shape that extends to cover not only the outer circumferential surface of the terminal exposed portion 172a but also a part of the upper surface.

[0503] When the second gasket 173 is made of a polymer resin, the second gasket 173 can be bonded to the battery housing 171 and the terminal 172 by heat fusion. In this case, the airtightness at the bonding interface between the second gasket 173 and the terminal 172 and the bonding interface between the second gasket 173 and the battery housing 171 is enhanced. On the other hand, when the gasket exposed portion 173a of the second gasket 173 extends to the upper surface of the terminal exposed portion 172a, the terminal 172 may be integrally bonded to the second gasket 173 by insert injection molding.

[0504] On the upper surface of the battery housing 171, the area 175 other than the area occupied by terminal 172 and the second gasket 173 corresponds to the second electrode terminal having opposite polarity to terminal 172.

[0505] The second current collector 176 is coupled to the lower part of the electrode assembly 141. The second current collector 176 is made of a conductive metallic material such as aluminum, steel, copper, or nickel, and is electrically connected to the second blank portion 146b of the second electrode.

[0506] Preferably, the second current collector 176 is electrically connected to the battery housing 171. Therefore, the second current collector 176 can be fixed by interposing at least a portion of its peripheral edge between the inner surface of the battery housing 171 and the first gasket 178b. As an example, at least a portion of the peripheral edge of the second current collector 176 can be fixed to the beading portion 180 formed at the lower end of the battery housing 171 by welding, while being supported by the lower end surface of the beading portion 180. In a modified example, at least a portion of the peripheral edge of the second current collector 176 can be directly welded to the inner wall surface of the battery housing 171.

[0507] The second current collector 176 may have a plurality of radially formed bumps (not shown) on the surface facing the second blank portion 146b. If bumps are formed, the second current collector 176 can be pressed against the bumps to push the second blank portion 146b into the bumps.

[0508] Preferably, the second current collector 176 and the end of the second plain portion 146b can be joined by welding, for example, laser welding. The welded portion between the second current collector 176 and the second plain portion 146b can be spaced apart by a predetermined distance toward the core C with respect to the inner circumferential surface of the beading portion 180.

[0509] The seal 178 that seals the lower open end of the battery housing 171 includes a plate-shaped cap 178a and a first gasket 178b. The first gasket 178b electrically isolates the cap 178a from the battery housing 171. The crimping portion 181 secures the periphery of the cap 178a and the first gasket 178b together. The cap 178a is provided with a vent portion 179. The configuration of the vent portion 179 is substantially the same as that of the above-described embodiment (modified form). The lower surface of the cap 178a may be located above the lower end of the crimping portion 181. In this case, a space is formed below the cap 178a, allowing for smooth ventilation. This is particularly useful when the cylindrical battery 170 is installed so that the crimping portion 181 faces in the direction of gravity.

[0510] Preferably, the cap 178a is made of a conductive metal material. However, since the first gasket 178b is interposed between the cap 178a and the battery housing 171, the cap 178a does not have electrical polarity. The seal 178 mainly serves to seal the open end at the bottom of the battery housing 171 and to release gas when the internal pressure of the battery 170 increases above a critical value. The critical value of the internal pressure is 15 kgf / cm². 2 ~35 kgf / cm² 2 That is the case.

[0511] Preferably, the terminal 172 electrically connected to the first blank portion 146a of the first electrode is used as the first electrode terminal. In addition, the portion 175 of the upper surface of the battery housing 171, excluding the terminal 172, which is electrically connected to the second blank portion 146b of the second electrode through the second current collector 176, is used as the second electrode terminal with opposite polarity to the first electrode terminal. In this way, when the two electrode terminals are located on the upper part of the cylindrical battery 170, it is possible to arrange electrical connection components such as busbars on only one side of the cylindrical battery 170. This can lead to a simplification of the battery pack structure and an improvement in energy density. Furthermore, since the portion 175 used as the second electrode terminal has a substantially flattened shape, it is possible to secure a sufficient connection area for connecting electrical connection components such as busbars. As a result, the cylindrical battery 170 can reduce the resistance at the connection points of the electrical connection components to a desirable level.

[0512] On the other hand, the structure of the electrode assembly 141 and the structure of the plain part are not limited to those shown in the figures, and can be replaced with the structures of the above-described embodiments (modified forms).

[0513] Figure 21 is a cross-sectional view of a cylindrical battery 180 according to yet another embodiment of the present invention, cut along the Y-axis.

[0514] Referring to Figure 21, the cylindrical battery 180 has substantially the same structure as the cylindrical battery 150 shown in Figure 18 in terms of the electrode assembly 141, and the other components, excluding the electrode assembly 141, are substantially the same as the cylindrical battery 170 shown in Figure 20.

[0515] Therefore, the configurations of the embodiments (modified forms) of the cylindrical batteries 150 and 170 can be similarly applied to the cylindrical battery 180.

[0516] Furthermore, the structure of the electrode assembly 141 and the structure of the plain part are not limited to those shown in the figures, and can be replaced with the structures of the above-described embodiments (modified forms).

[0517] Figure 22 is a cross-sectional view of a cylindrical battery 190 according to yet another embodiment of the present invention, cut along the Y-axis.

[0518] Referring to Figure 22, the cylindrical battery 190 includes the electrode assembly 110 shown in Figure 14, and the other components, excluding the electrode assembly 110, are substantially the same as those of the cylindrical battery 140 shown in Figure 17. Therefore, the configurations described with reference to Figures 14 and 17 can be applied substantially similarly to this embodiment.

[0519] Referring to Figures 10a and 22, the first blank portion 146a and the second blank portion 146b of the electrode assembly 110 are bent radially, for example, from the outer circumference to the core, forming a bent surface region F.

[0520] The first section B1 is shorter in height than the other sections and corresponds to the segment omission section a1 where no segment exists, so it cannot be folded towards the core.

[0521] Preferably, the bent surface region F may include a section a1 where the segment is omitted, a section a2 where the height of the segment is variable, and a section a3 where the height of the segment is uniform, from the core side to the outer circumference.

[0522] As shown in Figures 10c, 10d, and 10e, the bent surface region F includes a uniform layering section b1 adjacent to the sectioning omission section a1, where the number of layering sections is 10 or more.

[0523] The bent surface region F may also include a layer count reduction section b2 adjacent to the outer circumference of the electrode assembly 110, where the number of layers of segmentation decreases toward the outer circumference. Preferably, the uniform layer count section b1 may be set as a welding target region.

[0524] In the folded surface region F, the preferred numerical ranges for the ratio of the height variable section a2 (a2 / c) to the radius region (c) including the segmental section, the ratio of the uniform number of layers section b1 (b1 / c) to the radius region (c) including the segmental section, and the ratio of the area of ​​the uniform number of layers section b1 to the area of ​​the folded surface region F have been described above, so a repeated explanation will be omitted.

[0525] The first current collector 144 can be laser-welded to the bent surface region F of the first plain section 146a, and the second current collector 145 can be laser-welded to the bent surface region F of the second plain section 146b. The welding method can be replaced with ultrasonic welding, resistance welding, spot welding, etc.

[0526] Preferably, 50% or more of the welding area W of the first current collector 144 and the second current collector 145 may overlap with the uniform layer number section b1 of the bent surface area F. Selectively, the remaining area of ​​the welding area W may overlap with the decreasing layer number section b2 of the bent surface area F. It is more preferable for the entire welding area W to overlap with the uniform layer number section b1 in terms of high welding strength, low resistance at the welding interface, and prevention of damage to the separation film and active material layer.

[0527] Preferably, in the uniform layer number section b1 that overlaps with the welding region W, and optionally in the decreasing layer number section b2, the number of layers of the segment can be 10 to 35.

[0528] Selectively, if the number of layers in the segment of the layer-reducing section b2 that overlaps the welding area W is less than 10, the laser output for welding the layer-reducing section b2 may be lower than the laser output for welding the layer-uniform section b1. That is, when the welding area W overlaps simultaneously with the layer-uniform section b1 and the layer-reducing section b2, the laser output can be varied according to the number of layers in the segment. In this case, the welding strength in the layer-uniform section b1 may be greater than the welding strength in the layer-reducing section b2.

[0529] In the bent surface regions F formed on the upper and lower parts of the electrode assembly 110, the radial lengths of the segment omission section a1 and / or the segment height variable section a2 and / or the segment height uniform section a3 may be the same or different.

[0530] In the electrode assembly 110, the height of the first part B1 is relatively lower than that of the other parts. Also, as shown in Figure 14, the bend length H of the plain section located on the innermost side of the third part B2 is smaller than the sum of the radial length R of the first part B1 and 10% of the radius of the core 112.

[0531] Therefore, even if the first blank portion 146a is bent toward the core, more than 90% of the diameter of the core 112 of the electrode assembly 110 can be exposed to the outside. If the core 112 is not blocked, there is no interference with the electrolyte injection process, and the efficiency of electrolyte injection is improved. In addition, a welding jig can be inserted through the core 112 to facilitate the welding process between the second current collector 145 and the battery housing 142.

[0532] If the plain sections 146a and 146b have a segmented structure, adjusting the width and / or height and / or spacing pitch of the segmented pieces to satisfy the numerical range of the above-described embodiment will result in the segmented pieces overlapping multiple times to a degree that sufficient welding strength can be ensured, without forming any gaps in the bent surface region F when the segmented pieces are bent.

[0533] Preferably, the first current collector 144 and the second current collector 145 may have an outer diameter that covers the ends of the segmental sections (see 61, 61' in Figure 10f) that are bent in the last winding turn of the uniform height section a3 of the first and second electrodes. In this case, welding is possible with the segmental sections forming the bent surface region F uniformly pressed by the current collectors, and the tightly stacked state of the segmental sections can be maintained even after welding. A tightly stacked state means a state in which there is substantially no gap between the segmental sections, as shown in Figure 10a. A tightly stacked state contributes to reducing the resistance of the cylindrical battery 190 to a level suitable for rapid charging (e.g., 4 mΩ) or below.

[0534] The structure of the plain sections 146a and 146b can be changed to the structure according to the embodiment (modified form) described above. Furthermore, it is not limited that the conventional structure of the plain section may be applied to either one of the plain sections 146a or 146b.

[0535] When blank sections 146a and 146b, which include multiple segment sections 61 and 61', are provided with cut-out sections (62 in Figures 7i to 7n), even if stress exceeding a critical value is applied to the segment sections 61 and 61' welded to the first current collector 144 and the second current collector 145 due to vibration or swelling of the electrode assembly 110, the stress is relieved by the fracture of the cut-out section 62 near the welded area. Therefore, it is possible to prevent internal short circuits from occurring due to active material debris generated as both the blank sections 146a and 146b and the active material section break due to the stress.

[0536] Figure 23 is a cross-sectional view of a cylindrical battery 200 according to yet another embodiment of the present invention, cut along the Y-axis.

[0537] Referring to Figure 23, the cylindrical battery 200 includes the electrode assembly 110 shown in Figure 14, and the other components, excluding the electrode assembly 110, are substantially the same as those of the cylindrical battery 180 shown in Figure 21. Therefore, the configurations described with reference to Figures 14 and 21 can be applied substantially similarly to this embodiment.

[0538] Referring to Figures 10a and 23, the first blank portion 146a and the second blank portion 146b of the electrode assembly 110 are bent radially, for example, from the outer circumference to the core, forming a bent surface region F.

[0539] The first section B1 is shorter in height than the other sections and corresponds to the segment omission section a1 where no segment exists, so it cannot be folded towards the core.

[0540] Preferably, the bent surface region F may include a section a1 where the segment is omitted, a section a2 where the height of the segment is variable, and a section a3 where the height of the segment is uniform, from the core side to the outer circumference.

[0541] As shown in Figures 10c, 10d, and 10e, the bent surface region F includes a uniform layering section b1 adjacent to the sectioning omission section a1, where the number of layering sections is 10 or more.

[0542] The bent surface region F may also include a layer count reduction section b2 adjacent to the outer circumference of the electrode assembly 110, where the number of layers of segmentation decreases toward the outer circumference. Preferably, the uniform layer count section b1 may be set as a welding target region.

[0543] In the folded surface region F, the preferred numerical ranges for the ratio of the height variable section a2 (a2 / c) to the radius region (c) including the segmental section, the ratio of the uniform number of layers section b1 (b1 / c) to the radius region (c) including the segmental section, and the ratio of the area of ​​the uniform number of layers section b1 to the area of ​​the folded surface region F have been described above, so a repeated explanation will be omitted.

[0544] The first current collector 144 can be laser-welded to the bent surface region F of the first plain section 146a, and the second current collector 176 can be laser-welded to the bent surface region F of the second plain section 146b. The welding method can be replaced with ultrasonic welding, resistance welding, spot welding, etc. The welding region W between the second current collector 176 and the second plain section 146b can be separated from the inner surface of the beading section 180 by a predetermined distance.

[0545] Preferably, more than 50% of the welding area W of the first current collector 144 and the second current collector 176 may overlap with the uniform layer number section b1 of the bent surface area F. Selectively, the remaining area of ​​the welding area W may overlap with the decreasing layer number section b2 of the bent surface area F. It is more preferable for the entire welding area W to overlap with the uniform layer number section b1 in terms of high welding strength, low resistance at the welding interface, and prevention of damage to the separation film and active material layer.

[0546] Preferably, in the uniform layer number section b1 that overlaps with the welding region W, and optionally in the decreasing layer number section b2, the number of layers of the segment can be 10 to 35.

[0547] Selectively, if the number of layers in the segment of the layer-reducing section b2 that overlaps the welding area W is less than 10, the laser output for welding the layer-reducing section b2 may be lower than the laser output for welding the layer-uniform section b1. That is, when the welding area W overlaps simultaneously with the layer-uniform section b1 and the layer-reducing section b2, the laser output can be varied according to the number of layers in the segment. In this case, the welding strength in the layer-uniform section b1 may be even greater than the welding strength in the layer-reducing section b2.

[0548] In the bent surface regions F formed on the upper and lower parts of the electrode assembly 110, the radial lengths of the segment omission section a1 and / or the segment height variable section a2 and / or segment height uniform section a3 may be the same or different from each other.

[0549] In the electrode assembly 110, the height of the first part B1 is relatively lower than that of the other parts. Also, as shown in Figure 14, the bend length H of the plain section located on the innermost side of the third part B2 is smaller than the sum of the radial length R of the first part B1 and 10% of the radius of the core 112.

[0550] Therefore, even if the first blank portion 146a is bent toward the core, more than 90% of the diameter of the core 112 of the electrode assembly 110 can be exposed to the outside. If the core 112 is not blocked, there is no interference with the electrolyte injection process, and the efficiency of electrolyte injection is improved. In addition, a welding jig can be inserted through the core 112 to easily perform the welding process between the first current collector 144 and the terminal 172.

[0551] When the first plain section 146a and the second plain section 146b have a segmented structure, if the width and / or height and / or spacing pitch of the segmented pieces are adjusted to satisfy the numerical range of the above-described embodiment, when the segmented pieces are bent, they overlap in sufficient quantities to ensure sufficient welding strength, and do not form any gaps in the bent surface region F.

[0552] Preferably, the first current collector 144 and the second current collector 176 may have an outer diameter such that the regions in contact with the first blank portion 146a and the second blank portion 146b cover the ends of the segmental sections (see 61, 61' in Figure 10f) that are bent in the last winding turn of the uniform height section a3 of the first and second electrodes. In this case, welding is possible with the segmental sections forming the bent surface region F uniformly pressed by the current collector, and a tightly stacked state of the segmental sections can be maintained even after welding. A tightly stacked state means a state in which there is substantially no gap between the segmental sections, as shown in Figure 10a. A tightly stacked state contributes to reducing the resistance of the cylindrical battery 200 to a level suitable for rapid charging (e.g., 4 mΩ) or below.

[0553] The structure of the plain sections 146a and 146b can be changed to the structure according to the embodiment (modified form) described above. Furthermore, it is not limited that the conventional structure of the plain section may be applied to either one of the plain sections 146a or 146b.

[0554] When blank sections 146a and 146b, which include multiple segment sections 61 and 61', are provided with cut-out sections (62 in Figures 7i to 7n), even if stress exceeding a critical value is applied to the segment sections 61 and 61' welded to the first current collector 144 and the second current collector 176 due to vibration or swelling of the electrode assembly 110, the stress is relieved by the fracture of the cut-out section 62 near the welded area. Therefore, it is possible to prevent internal short circuits from occurring due to active material debris generated as both the blank sections 146a and 146b and the active material section break due to the stress.

[0555] Figure 24 is a cross-sectional view of a cylindrical battery 210 according to yet another embodiment of the present invention, cut along the Y-axis.

[0556] Referring to Figure 24, the cylindrical battery 210 includes the electrode assembly 100 shown in Figure 13, and the other components, excluding the electrode assembly 100, are substantially the same as those of the cylindrical battery 140 shown in Figure 17. Therefore, the configurations described with reference to Figures 13 and 17 can be applied substantially similarly to this embodiment.

[0557] Preferably, the first blank portion 146a and the second blank portion 146b of the electrode assembly 100 are divided into a plurality of segments, and the plurality of segments are bent radially of the electrode assembly 100, for example, from the outer circumference to the core. In this case, the first portion B1 and the second portion B3 of the first blank portion 146a are shorter in height than the other portions and do not contain segments, and therefore are not substantially bent. The same applies to the second blank portion 146b.

[0558] In this embodiment as well, the bent surface region F may include a section a1 where the segment is omitted, a section a2 where the height of the segment is variable, and a section a3 where the height of the segment is uniform, from the core side to the outer circumference. However, since the second portion B3 is not bent, the radial length of the bent surface region F may be shorter than in the embodiment described above.

[0559] As shown in Figures 10c, 10d, and 10e, the bent surface region F includes a uniform layering section b1 adjacent to the sectioning omission section a1, where the number of layering sections is 10 or more.

[0560] The bent surface region F may also include a layer count reduction section b2 adjacent to the second portion B3 of the electrode assembly 110, where the number of layer counts decreases toward the outer periphery. Preferably, the uniform layer count section b1 may be set as a welding target region.

[0561] In the folded surface region F, the preferred numerical ranges for the ratio of the height variable section a2 (a2 / c) to the radius region (c) including the segmental section, the ratio of the uniform number of layers section b1 (b1 / c) to the radius region (c) including the segmental section, and the ratio of the area of ​​the uniform number of layers section b1 to the area of ​​the folded surface region F have been described above, so repeated explanations will be omitted.

[0562] The first current collector 144 can be welded to the bent surface region F of the first plain section 146a, and the second current collector 145 can be welded to the bent surface region F of the second plain section 146b.

[0563] The overlapping relationship between the uniform layer number section b1 and the decreasing layer number section b2 and the welding area W, the outer diameters of the first current collector 144 and the second current collector 145, and the configuration in which the first part B1 does not block more than 10% of the core diameter are essentially as described above.

[0564] On the other hand, the second part B3 does not contain any segmentation and is lower in height than the third part B2. Therefore, when the first plain part 146a is folded, the second part B3 is not substantially folded. Also, since the second part B3 is sufficiently separated from the beading part 147, the problem of the second part B3 being damaged during the process of the beading part 147 being pressed in can be solved.

[0565] The structure of the plain sections 146a and 146b can be changed to the structure according to the embodiment (modified form) described above. Furthermore, it is not limited that the conventional structure of the plain section may be applied to either one of the plain sections 146a or 146b.

[0566] When blank sections 146a and 146b, which include multiple segment sections 61 and 61', are provided with cut-out sections (62 in Figures 7i to 7n), even if stress exceeding a critical value is applied to the segment sections 61 and 61' welded to the first current collector 144 and the second current collector 145 due to vibration or swelling of the electrode assembly 100, the stress is relieved by the fracture of the cut-out section 62 near the welded area. Therefore, it is possible to prevent internal short circuits from occurring due to active material debris generated as both the blank sections 146a and 146b and the active material section break due to the stress.

[0567] Figure 25 is a cross-sectional view of a cylindrical battery 220 according to yet another embodiment of the present invention, cut along the Y-axis.

[0568] Referring to Figure 25, the cylindrical battery 220 includes the electrode assembly 100 shown in Figure 24, and the other components, excluding the electrode assembly 100, are substantially the same as those of the cylindrical battery 180 shown in Figure 21. Therefore, the configurations described with reference to Figures 21 and 24 can be applied substantially similarly to this embodiment.

[0569] Preferably, the first blank portion 146a and the second blank portion 146b of the electrode assembly 100 are divided into a plurality of segments and can be folded from the outer circumference towards the core. In this case, the first portion B1 and the second portion B3 of the first blank portion 146a are lower in height than the other portions and do not contain a segment structure, so they are not substantially folded towards the core. The same applies to the second blank portion 146b.

[0570] Therefore, in this embodiment as well, similar to the embodiment in Figure 24, the bent surface region F may include a section a1 where the segment is omitted, a section a2 where the height of the segment is variable, and a section a3 where the height of the segment is uniform, from the core side to the outer circumference. However, since the second portion B3 is not bent, the radial length of the bent surface region F may be shorter than in the embodiment described above.

[0571] As shown in Figures 10c, 10d, and 10e, the bent surface region F includes a uniform layering section b1 adjacent to the sectioning omission section a1, where the number of layering sections is 10 or more.

[0572] The bent surface region F may also include a layer count reduction section b2 adjacent to the second portion B3 of the electrode assembly 110, where the number of layer counts decreases toward the outer periphery. Preferably, the uniform layer count section b1 may be set as a welding target region.

[0573] In the folded surface region F, the preferred numerical ranges for the ratio of the height variable section a2 (a2 / c) to the radius region (c) including the segmental section, the ratio of the uniform number of layers section b1 (b1 / c) to the radius region (c) including the segmental section, and the ratio of the area of ​​the uniform number of layers section b1 to the area of ​​the folded surface region F have been described above, so repeated explanations will be omitted.

[0574] The first current collector 144 can be welded to the bent surface region F of the first plain section 146a, and the second current collector 176 can be welded to the bent surface region F of the second plain section 146b.

[0575] The overlapping relationship between the uniform layer number section b1 and the decreasing layer number section b2 and the welding area W, the outer diameters of the first current collector 144 and the second current collector 176, and the configuration in which the first part B1 does not block more than 10% of the core diameter are essentially as described above.

[0576] The structure of the plain sections 146a and 146b can be changed to the structure according to the embodiment (modified form) described above. Furthermore, it is not limited that the conventional structure of the plain section may be applied to either one of the plain sections 146a or 146b.

[0577] In the above-described embodiment (modified form), the first current collector 144 and the second current collector 176 included in the cylindrical batteries 170, 180, 200, and 220, which include the terminal 172, may have an improved structure as shown in Figures 26 and 27.

[0578] The improved structure of the first current collector 144 and the second current collector 176 can contribute to improving vibration resistance and energy density while reducing the resistance of the cylindrical battery. In particular, the first current collector 144 and the second current collector 176 are effective when applied to large cylindrical batteries with a height-to-diameter ratio greater than 0.4.

[0579] When blank sections 146a and 146b, which include multiple segmental sections 61 and 61', are provided with cut-out sections (62 in Figures 7i to 7n), even if stress exceeding a critical value is applied to the segmental sections 61 and 61' welded to the first current collector 144 and the second current collector 176 due to vibration or swelling of the electrode assembly 100, the stress is relieved by the fracture of the cut-out section 62 near the welded area. Therefore, it is possible to prevent internal short circuits from occurring due to active material debris generated as both the blank sections 146a and 146b and the active material section fracture due to the stress.

[0580] Figure 26 is a top view showing the structure of the first current collector 144 according to an embodiment of the present invention.

[0581] Referring to Figures 23 and 26, the first current collector 144 may include a peripheral portion 144a, a first blank portion connecting portion 144b, and a terminal connecting portion 144c. The peripheral portion 144a is positioned on the upper part of the electrode assembly 110. The peripheral portion 144a has an internal space S inside it. open It may have a substantially rim shape in which the peripheral edge portion 144a is formed. The drawings only show the case where the peripheral edge portion 144a is substantially circular in shape, but this does not limit the present invention. The peripheral edge portion 144a may be substantially square, hexagonal, octagonal, or any other rim shape, contrary to the figures shown. The number of peripheral edges 144a may be increased to two or more. In this case, another peripheral edge portion of the rim shape may be included inside the peripheral edge portion 144a.

[0582] The terminal coupling portion 144c may have a diameter that is the same as or larger than the diameter of the flat portion 172c formed on the bottom surface of the terminal 172, in order to secure a welding area for coupling with the flat portion 172c formed on the bottom surface of the terminal 172.

[0583] The first plain portion joining portion 144b extends inward from the peripheral portion 144a and is joined to the first plain portion 146a by welding. The terminal joining portion 144c is located inside the peripheral portion 144a, separated from the first plain portion joining portion 144b. The terminal joining portion 144c can be joined to the terminal 172 by welding. The terminal joining portion 144c is located in an inner space S surrounded, for example, by the peripheral portion 144a. open It may be located approximately in the center. The terminal coupling portion 144c may be provided at a position corresponding to a hole formed in the core C of the electrode assembly 110. The terminal coupling portion 144c may be configured to cover the hole formed in the core C of the electrode assembly 110 so that the hole is not exposed to the outside of the terminal coupling portion 144c. Therefore, the terminal coupling portion 144c may have a larger diameter or width than the hole formed in the core C of the electrode assembly 110.

[0584] The first blank portion connecting portion 144b and the terminal connecting portion 144c are not directly connected but are arranged separately and can be indirectly connected by the peripheral portion 144a. In this way, the first current collector 144 has a structure in which the first blank portion connecting portion 144b and the terminal connecting portion 144c are not directly connected but are connected through the peripheral portion 144a, so that when shock and / or vibration occurs in the cylindrical battery 200, the shock applied to the connection part between the first blank portion connecting portion 144b and the first blank portion 146a and the connection part between the terminal connecting portion 144c and the terminal 172 can be dispersed. Although four first blank portion connecting portions 144b are shown in the drawings, the present invention is not limited thereto. The number of the first blank portion connecting portions 144b is determined by the inner space S of the peripheral portion 144a, taking into consideration the difficulty of manufacturing due to the complexity of the shape, electrical resistance, and electrolyte impregnation. open Various factors can be taken into consideration when making a decision.

[0585] The first current collector 144 may further include a bridge portion 144d that extends inward from the peripheral portion 144a and is connected to the terminal coupling portion 144c. The bridge portion 144d may be formed with a cross-sectional area smaller than that of the first plain portion coupling portion 144b and the peripheral portion 144a, at least in part. For example, the bridge portion 144d may be formed with a width and / or thickness that is even smaller than that of the first plain portion coupling portion 144b, at least in part. In this case, the electrical resistance of the bridge portion 144d increases. As a result, when current flows through the bridge portion 144d, the relatively large resistance causes melting due to overcurrent heating in part of the bridge portion 144d, which irreversibly interrupts the overcurrent. The cross-sectional area of ​​the bridge portion 144d may be adjusted to an appropriate level to take such overcurrent interruption function into consideration.

[0586] The bridge portion 144d may include a tapered portion 144e whose width gradually narrows from the inner surface of the peripheral portion 144a toward the terminal coupling portion 144c. When the tapered portion 144e is provided, the rigidity of the component is improved at the connection point between the bridge portion 144d and the peripheral portion 144a. When the tapered portion 144e is provided, in the manufacturing process of the cylindrical battery 200, for example, a transfer device and / or an operator can easily and safely transfer the first current collector 144 and / or the assembly of the first current collector 144 and the electrode assembly 110 by gripping the tapered portion 144e. In other words, when the tapered portion 144e is provided, product defects that occur when gripping parts that are welded to other parts, such as the first plain portion coupling portion 144b and the terminal coupling portion 144c, can be prevented.

[0587] Multiple first plain portion joining portions 144b may be provided. Multiple first plain portion joining portions 144b may be arranged at equal intervals from one another along the extension direction of the peripheral portion 144a. The extended lengths of each of the multiple first plain portion joining portions 144b may be substantially the same. The first plain portion joining portions 144b may be joined to the bent surface region F of the first plain portion 146a by laser welding. Welding may be replaced by ultrasonic welding, spot welding, or the like.

[0588] The weld pattern 144f formed by welding the first plain joint portion 144b and the bent surface region F may have a structure that extends along the radial direction of the electrode assembly 110. The weld pattern 144f may be an arrangement of line patterns or dot patterns.

[0589] The welding pattern 144f corresponds to the welding area. Therefore, it is preferable that the welding pattern 144f overlaps with the uniform layer number section b1 of the bent surface area F by 50% or more. The welding pattern 144f that does not overlap with the uniform layer number section b1 may overlap with the decreasing layer number section b2. More preferably, the entire welding pattern 144f may overlap with the uniform layer number section b1 of the bent surface area F. It is preferable that the uniform layer number section b1 and the selectively decreasing layer number section b2 of the bent surface area F below the point where the welding pattern 144f is formed have 10 or more layers per segment.

[0590] The terminal coupling portion 144c may be arranged so as to be surrounded by a plurality of the first plain portion coupling portions 144b. The terminal coupling portion 144c may be joined to the flat portion 172c of the terminal 172 by welding. The bridge portion 144d may be located between a pair of adjacent first plain portion coupling portions 144b. In this case, the distance from the bridge portion 144d to one of the pair of first plain portion coupling portions 144b along the extension direction of the peripheral portion 144a may be substantially the same as the distance from the bridge portion 144d to the other of the pair of first plain portion coupling portions 144b along the extension direction of the peripheral portion 144a. The cross-sectional area of ​​each of the plurality of first plain portion coupling portions 144b may be formed to be substantially the same. The width and thickness of each of the plurality of first plain portion coupling portions 144b may be formed to be substantially the same.

[0591] Although not shown in the figures, there may be multiple bridge portions 144d. Each of the multiple bridge portions 144d may be positioned between adjacent pairs of first plain portion connecting portions 144b. The multiple bridge portions 144d may be positioned at approximately equal intervals from one another along the extension direction of the peripheral portion 144a. The distance from each of the multiple bridge portions 144d to one of adjacent pairs of first plain portion connecting portions 144b along the extension direction of the peripheral portion 144a may be approximately the same as the distance to the other first plain portion connecting portion 144b.

[0592] As described above, when multiple first blank section connecting portions 144b and / or bridge portions 144d are provided, if the distance between the first blank section connecting portions 144b and / or the distance between the bridge portions 144d and / or the distance between the first blank section connecting portions 144b and bridge portions 144d is kept constant, then a smooth flow of current from the first blank section connecting portions 144b to the bridge portions 144d or from the bridge portions 144d to the first blank section connecting portions 144b will be formed.

[0593] The bridge portion 144d may include a notching portion N formed to partially reduce the cross-sectional area of ​​the bridge portion 144d. Adjustment of the cross-sectional area of ​​the notching portion N can be achieved, for example, by partially reducing the width and / or thickness of the bridge portion 144d. When the notching portion N is provided, the electrical resistance in the region in which the notching portion N is formed increases, thereby enabling rapid current interruption in the event of an overcurrent.

[0594] The notch N is preferably provided in a region corresponding to the uniform layering section of the electrode assembly 110 in order to prevent foreign matter generated during fracture from flowing into the inside of the electrode assembly 110. This is because in this region, the number of layers of the segment of the first blank section 146a is maintained at its maximum, and the overlapping segment can function as a mask.

[0595] The notch N may be covered and wrapped with insulating tape. In this case, the heat generated in the notch N will not be dissipated to the outside, and when an overcurrent flows through the bridge portion 144d, the notch N will break more quickly.

[0596] Figure 27 is a top view showing the structure of the second current collector 176 according to an embodiment of the present invention.

[0597] Referring to Figures 23 and 27, the second current collector 176 is positioned at the bottom of the electrode assembly 110. The second current collector 176 may also be configured to electrically connect the plain portion 146b of the electrode assembly 110 to the battery housing 171. The second current collector 176 is made of a conductive metallic material and is electrically connected to the bent surface region F of the plain portion 146b. The second current collector 176 is also electrically connected to the battery housing 171. The peripheral portion of the second current collector 176 may be interposed and fixed between the inner surface of the battery housing 171 and the first gasket 178b. Specifically, the peripheral portion of the second current collector 176 may be interposed between the lower surface of the beading portion 180 of the battery housing 171 and the first gasket 178b. However, this does not limit the present invention, and alternatively, the peripheral portion of the second current collector 176 may be welded to the inner wall surface of the battery housing 171 in an area where the beading portion 180 is not formed.

[0598] The second current collector 176 may include a support portion 176a positioned at the bottom of the electrode assembly 110, a second plain portion connecting portion 176b extending substantially radially from the support portion 176a and coupled to the bent surface region F of the plain portion 146b, and a housing connecting portion 176c extending inclined toward the inner surface of the battery housing 171 with respect to the radial direction of the electrode assembly 110 from the support portion 176a and coupled to the inner surface. The second plain portion connecting portion 176b and the housing connecting portion 176c are indirectly connected through the support portion 176a and are not directly connected to each other. Therefore, when an external impact is applied to the cylindrical battery 200 according to one embodiment of the present invention, damage to the coupling portion between the second current collector 176 and the electrode assembly 110 and the coupling portion between the second current collector 176 and the battery housing 171 can be minimized. However, the second current collector 176 according to one embodiment of the present invention is not limited to having a structure in which the second blank portion coupling portion 176b and the housing coupling portion 176c are indirectly connected. For example, the second current collector 176 may have a structure in which there is no support portion 176a that indirectly connects the second blank portion coupling portion 176b and the housing coupling portion 176c, and / or a structure in which the blank portion 146b and the housing coupling portion 176c are directly connected.

[0599] The support portion 176a and the second plain portion connecting portion 176b are positioned at the bottom of the electrode assembly 110. The second plain portion connecting portion 176b is connected to the bent surface region F of the plain portion 146b. Not only the second plain portion connecting portion 176b, but the support portion 176a can also be connected to the plain portion 146b. The second plain portion connecting portion 176b and the bent surface region F of the plain portion 146b can be connected by laser welding. Welding can be replaced by ultrasonic welding, spot welding, etc. The support portion 176a and the second plain portion connecting portion 176b are positioned above the beading portion 180 if a beading portion 180 is formed on the battery housing 171.

[0600] The support portion 176a includes a current collector hole 176d formed at a position corresponding to a hole formed in the core C of the electrode assembly 110. The core C of the electrode assembly 110 and the current collector hole 176d, which are in communication with each other, can function as a passage for inserting a welding rod for welding between the terminal 172 and the terminal coupling portion 144c of the first current collector 144, or for irradiating with a laser beam.

[0601] The current collector hole 176d is a hole formed in the core C of the electrode assembly 110 with radius r c 0.5r c It may have a radius greater than or equal to the above. The radius of the current collector plate hole 176d is 0.5r c ~1.0r c In this case, when venting occurs in the cylindrical battery 200, the venting pressure prevents the separation membrane and electrode winding structure near the core C of the electrode assembly 110 from being pushed outwards from the core C. The radius of the current collector hole 176d is 1.0r c If the value is larger than this, the core C is opened to its maximum extent, making it easier to inject the electrolyte during the electrolyte injection process.

[0602] When multiple second blank portion connecting portions 176b are provided, the multiple second blank portion connecting portions 176b may have a configuration in which they extend substantially radially from the support portion 176a of the second current collector 176 toward the side wall of the battery housing 171. Each of the multiple second blank portion connecting portions 176b may be located spaced apart from each other along the perimeter of the support portion 176a.

[0603] Multiple housing coupling portions 176c may be provided. In this case, the multiple housing coupling portions 176c may have a configuration that extends substantially radially from the center of the second current collector 176 toward the side wall of the battery housing 171. This allows for electrical connection between the second current collector 176 and the battery housing 171 at multiple points. By performing coupling for electrical connection at multiple points in this way, the coupling area can be maximized and electrical resistance can be minimized. Each of the multiple housing coupling portions 176c may be located spaced apart from each other along the perimeter of the support portion 176a. At least one housing coupling portion 176c may be located between adjacent second plain portion coupling portions 176b. The multiple housing coupling portions 176c may be coupled to the inner surface of the battery housing 171, for example, to the beading portion 180. The housing coupling portions 176c may be coupled to the lower surface of the beading portion 180 in particular by laser welding. Welding can be replaced by ultrasonic welding, spot welding, etc. By welding multiple housing coupling portions 176c onto the beading portion 180 in this manner, the current path can be distributed radially, limiting the resistance level of the cylindrical battery 200 to approximately 4 mΩ or less. Furthermore, by shaping the lower surface of the beading portion 180 to extend in a direction substantially parallel to the upper surface of the battery housing 171, that is, in a direction substantially perpendicular to the side wall of the battery housing 171, and shaping the housing coupling portions 176c to extend in the same direction, that is, in the radial and circumferential directions, the housing coupling portions 176c can be stably contacted onto the beading portion 180. In addition, because the housing coupling portions 176c are stably contacted onto the flat portion of the beading portion 180 in this manner, welding between the two parts is performed smoothly, thereby improving the bonding force between the two parts and minimizing the increase in resistance at the joint.

[0604] The housing coupling portion 176c may include a contact portion 176e that is coupled to the inner surface of the battery housing 171, and a coupling portion 176f that connects the support portion 176a and the contact portion 176e.

[0605] The contact portion 176e is coupled to the inner surface of the battery housing 171. If a beading portion 180 is formed in the battery housing 171, the contact portion 176e may be coupled to the beading portion 180 as described above. More specifically, the contact portion 176e may be electrically connected to a flat portion formed on the lower surface of the beading portion 180 formed in the battery housing 171, and may be interposed between the lower surface of the beading portion 180 and the first gasket 178b. In this case, for stable contact and coupling, the contact portion 176e may have a form that extends for a predetermined length along the circumferential direction of the battery housing 171 in the beading portion 180.

[0606] The connecting portion 176f can be bent at an obtuse angle. The bending point may be above the midpoint of the connecting portion 176f. When the connecting portion 176f is bent, the contact portion 176e is stably supported on the flat surface of the beading portion 180. The connecting portion 176f is divided into a lower and upper part with respect to the bending point, and the length of the lower part may be greater than that of the upper part. Also, the inclination angle with respect to the surface of the support portion 176a may be even greater at the lower part of the bending point than at the upper part. When the connecting portion 176f is bent, it can buffer the pressure (force) applied vertically to the battery housing 171. For example, when pressure is transmitted to the contact portion 176e during the sizing process of the battery housing 171, and the contact portion 176e moves vertically toward the support portion 176a, the connecting portion 176f is deformed as the bending point of the connecting portion 176f moves upward, thereby buffering stress.

[0607] On the other hand, it is preferable that the maximum distance from the center of the second current collector 176 to the end of the second plain section connecting portion 176b along the radial direction of the electrode assembly 110 is the same as or smaller than the inner diameter of the battery housing 171 in the region where the beading portion 180 is formed, i.e., the minimum inner diameter of the battery housing 171. This is to prevent the end of the second plain section connecting portion 176b from pressing against the periphery of the electrode assembly 110 during the sizing process in which the battery housing 171 is compressed along the height direction.

[0608] The second plain joint 176b includes a hole 176g. The hole 176g can be used as a passage for the electrolyte to move. The weld pattern 176h formed by welding the second plain joint 176b and the bent surface region F may have a structure that extends along the radial direction of the electrode assembly 110. The weld pattern 176h may be an arrangement of line patterns or dot patterns.

[0609] The welding pattern 176h corresponds to the welding area. Therefore, it is preferable that the welding pattern 176h overlaps by 50% or more with the uniform layer number section b1 of the bent surface region F located at the bottom of the electrode assembly 110. The welding pattern 176h that does not overlap with the uniform layer number section b1 may overlap with the decreasing layer number section b2. More preferably, the entire welding pattern 176h may overlap with the uniform layer number section b1 of the bent surface region F. It is preferable that the uniform layer number section b1 and the selectively decreasing layer number section b2 of the bent surface region F located above the point where the welding pattern 176h is formed have 10 or more layers of segmented material.

[0610] The first current collector 144 and the second current collector 176 described above have different outer diameters. The outer diameter is the outer diameter of the outer edge of the contact area between the bent surface region F and the current collector. The outer diameter is defined as the maximum value of the distance between two points where a straight line passing through the center of the electrode assembly core C intersects with the edge of the contact area. Since the second current collector 176 is located inside the beading portion 180, its outer diameter is smaller than that of the first current collector 144. Also, the length of the welding pattern 144f of the first current collector 144 is even longer than the length of the welding pattern 176h of the second current collector 176. Preferably, the welding patterns 144f and 176h may extend outward from substantially the same point with respect to the center of the core C.

[0611] The cylindrical batteries 170, 180, 200, and 220 according to embodiments of the present invention can be electrically connected at the top.

[0612] Figure 28 is a top view showing multiple cylindrical batteries 200 electrically connected, and Figure 29 is a partial enlargement of Figure 28. The cylindrical battery 200 can be replaced with cylindrical batteries 170, 180, and 220 of other structures.

[0613] Referring to Figures 28 and 29, multiple cylindrical batteries 200 can be connected in series and parallel at the top of the cylindrical batteries 200 using busbars 210. The number of cylindrical batteries 200 can be increased or decreased depending on the capacity of the battery pack.

[0614] In each cylindrical battery 200, terminal 172 has positive polarity, and the flattened surface 171a around terminal 172 of the battery housing 171 may have negative polarity. Of course, the opposite is also possible.

[0615] Preferably, multiple cylindrical batteries 200 can be arranged in multiple columns and rows. In the drawing, columns are in the vertical direction and rows are in the horizontal direction. Also, in order to maximize space efficiency, the cylindrical batteries 200 can be arranged in a closest packing structure. A closest packing structure is formed when an equilateral triangle is drawn when the centers of the terminals 172 exposed on the outside of the battery housing 171 are connected. Preferably, the busbar 210 connects cylindrical batteries 200 arranged in the same column in parallel and connects cylindrical batteries 200 arranged in two adjacent columns in series.

[0616] Preferably, the busbar 210 may include a body portion 211, a plurality of first busbar terminals 212, and a plurality of second busbar terminals 213 for series and parallel connections.

[0617] The body portion 211 may extend along the row of cylindrical batteries 200 between adjacent terminals 172. Alternatively, the body portion 211 may extend along the row of cylindrical batteries 200 but be regularly bent in a zigzag pattern.

[0618] Multiple first busbar terminals 212 extend from one side of the body portion 211 and can be electrically coupled to terminals 172 of a cylindrical battery 200 located on the same side. The electrical coupling between the first busbar terminals 212 and terminals 172 can be performed by laser welding, ultrasonic welding, or the like.

[0619] Multiple second busbar terminals 213 can extend from the other side of the body portion 211 and be electrically connected to the flattened surface 171a around terminal 172 located on the other side. The electrical coupling between the second busbar terminals 213 and the flattened surface 171a can be performed by laser welding, ultrasonic welding, or the like.

[0620] Preferably, the body portion 211, the plurality of first busbar terminals 212, and the plurality of second busbar terminals 213 may be made of a single conductive metal plate. The metal plate may be, for example, an aluminum plate or a copper plate, but the present invention is not limited thereto. As a modified example, the body portion 211, the plurality of first busbar terminals 212, and the second busbar terminals 213 may be manufactured as separate pieces and then joined together by welding or the like.

[0621] The cylindrical battery 200 according to the embodiment described above has a structure in which resistance is minimized by increasing the welding area through the bent surface region F, doubling the current path using the second current collector 176, and minimizing the current path length. The AC resistance of the cylindrical battery 200, measured by a resistance meter between the positive electrode and the negative electrode, i.e., between the terminal 172 and the surrounding flattened surface 171a, can be 0.5 mΩ to 4 mΩ, preferably 1 mΩ to 4 mΩ, which is suitable for rapid charging.

[0622] In one embodiment of the present invention, the cylindrical battery 200 has a positive polarity terminal 172 and a negative polarity flattened surface 171a located in the same direction, making it easy to connect the cylindrical batteries 200 to each other using a busbar 210.

[0623] Furthermore, because the terminals 172 of the cylindrical battery 200 and the surrounding flat surface 171a have a large surface area, sufficient bonding area for the busbar 210 can be secured, and the resistance of the battery pack including the cylindrical battery 200 can be sufficiently reduced.

[0624] Furthermore, since electrical wiring can be performed on top of the cylindrical battery 200, the energy density per unit volume of the battery module / pack can be maximized.

[0625] The cylindrical battery according to the above-described embodiment (modified form) is used in the manufacture of a battery pack.

[0626] Figure 30 is a schematic diagram showing the configuration of a battery pack according to one embodiment of the present invention.

[0627] Referring to Figure 30, a battery pack 300 according to one embodiment of the present invention includes an assembly of electrically connected cylindrical batteries 301 and a pack housing 302 that houses them. The cylindrical batteries 301 may be any one of the batteries according to the embodiments (modified forms) described above. For convenience of illustration, components such as busbars, cooling units, and external terminals for the electrical connection of the cylindrical batteries 301 are not shown.

[0628] The battery pack 300 is installed in a vehicle. The vehicle may, for example, be an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The vehicle may include four-wheeled vehicles or two-wheeled vehicles.

[0629] Figure 31 is a diagram illustrating an automobile including the battery pack 300 shown in Figure 30.

[0630] Referring to Figure 31, an automobile V according to one embodiment of the present invention includes a battery pack 300 according to one embodiment of the present invention. The automobile V operates by receiving power from the battery pack 300 according to one embodiment of the present invention.

[0631] According to one embodiment of the present invention, the internal resistance of the battery can be reduced and the energy density increased by using the plain portions protruding from the upper and lower sides of the electrode assembly as electrode tabs.

[0632] Furthermore, according to one embodiment of the present invention, by improving the structure of the plain portion of the electrode assembly, interference between the electrode assembly and the inner circumferential surface of the battery housing is prevented during the process of forming the beading portion of the battery housing, thereby preventing internal short circuits in the cylindrical battery due to partial deformation of the electrode assembly.

[0633] Furthermore, according to one embodiment of the present invention, by improving the structure of the plain portion of the electrode assembly, it is possible to prevent the plain portion from tearing when bent, and to sufficiently increase the number of overlapping layers of the plain portion to improve the welding strength of the current collector.

[0634] Furthermore, according to one embodiment of the present invention, by applying a segmentation structure to the plain portion of the electrode and optimizing the dimensions of the segmentation segments (width, height, and spacing pitch) to sufficiently increase the number of stacked segmentation segments in the area used as the welding target area, the physical properties of the area to which the current collector is welded can be improved.

[0635] Furthermore, according to one embodiment of the present invention, when stress is concentrated in the region where the current collector is welded in the electrode assembly, the plain portion (or segment) in and / or near thereto breaks, thereby providing an electrode assembly having a structure that can prevent damage to the active material layer.

[0636] Furthermore, according to one embodiment of the present invention, by applying a structure in which a current collector is welded over a wide area to a bent surface region formed by bending a segment, it is possible to provide an electrode assembly with improved energy density and reduced resistance.

[0637] Furthermore, according to one embodiment of the present invention, it is possible to provide a cylindrical battery with an improved design that allows electrical wiring to be performed on top.

[0638] Furthermore, according to one embodiment of the present invention, by improving the structure of the plain portion adjacent to the core of the electrode assembly, it is possible to prevent the cavity in the core of the electrode assembly from becoming blocked when the plain portion is bent, thereby facilitating the electrolyte injection process and the welding process between the battery housing (or terminals) and the current collector.

[0639] Furthermore, according to one embodiment of the present invention, it is possible to provide a cylindrical battery having a structure with low internal resistance, prevention of internal short circuits, and improved welding strength between the current collector and the plain portion, a battery pack including the cylindrical battery, and an automobile.

[0640] In particular, the present invention can provide a cylindrical battery having a height-to-diameter ratio of 0.4 or more and a resistance of 4 mΩ or less, a battery pack including the cylindrical battery, and an automobile.

[0641] As described above, the present invention has been explained with limited embodiments and drawings, but it goes without saying that the present invention is not limited thereto, and that various modifications and variations are possible within the equivalent scope of the technical concept and claims of the present invention by persons with ordinary skill in the art to which the present invention belongs.

Claims

1. An electrode assembly having a core and an outer surface defined by winding a first electrode, a second electrode, and a separation membrane interposed between the first electrode and the second electrode around a winding shaft, The first electrode includes a first active material portion coated with an active material layer along the winding direction, and a first blank portion not coated with an active material layer, the first blank portion being exposed to the outside of the separation film. The first plain section includes a plurality of independently foldable segments, The aforementioned plurality of segments are defined as electrode tabs when bent along the radial direction of the electrode assembly, At least a portion of the area of ​​the first blank portion, which is provided with the plurality of segments, includes a cut portion that extends along one direction parallel to the winding direction, A cutting groove is interposed between adjacent segments along the winding direction, and the cutting portion is provided in the first blank area between the bottom of the cutting groove and the first active material portion. The cut portion is an electrode assembly spaced apart from the bottom of the cutting groove.

2. The electrode assembly according to claim 1, wherein each of the plurality of segments has the form of a geometric figure formed by connecting at least one straight line, at least one curve, or a combination thereof.

3. The electrode assembly according to claim 1, wherein the cut portion is formed continuously along one direction parallel to the winding direction of the electrode assembly in the region of the first blank portion where the plurality of sub-sections are provided.

4. The electrode assembly according to claim 1, wherein the cut portion is formed discontinuously along one direction parallel to the winding direction of the electrode assembly in the region of the first blank portion where the plurality of sub-sections are provided.

5. The electrode assembly according to claim 4, wherein the cut portion includes a plurality of sub-cut portions formed discontinuously along one direction parallel to the winding direction of the electrode assembly, and the first blank portion includes a section in which the length of the sub-cut portions gradually increases or decreases along the winding direction of the electrode assembly.

6. The electrode assembly according to claim 4, wherein the cut portion includes a plurality of sub-cut portions formed discontinuously along one direction parallel to the winding direction of the electrode assembly, and the first blank portion includes a section in which the separation distance between adjacent sub-cut portions gradually increases or decreases along the winding direction of the electrode assembly.

7. The electrode assembly according to claim 4, wherein the cut portion includes a plurality of sub-cut portions formed discontinuously along one direction parallel to the winding direction of the electrode assembly, and the heights of the plurality of sub-cut portions with respect to the active material layer are substantially the same in the winding axis direction.

8. The electrode assembly according to claim 4, wherein the cut portion includes a plurality of sub-cut portions formed discontinuously along one direction parallel to the winding direction of the electrode assembly, and the first blank portion includes a region in which the heights of the plurality of sub-cut portions differ in the winding axis direction relative to the active material layer.

9. The electrode assembly according to claim 4, wherein the cut portion includes a plurality of sub-cut portions formed discontinuously along one direction parallel to the winding direction of the electrode assembly, and the first blank portion includes a section in which the distance between the cutting groove and the sub-cut portions gradually increases or decreases along the winding direction of the electrode assembly.

10. The electrode assembly according to claim 1, wherein the distance between the cut portion and the bottom of the cutting groove is 0.1 mm to 1.9 mm.

11. The electrode assembly according to claim 1, wherein the cut portion includes an arrangement of a plurality of punch holes along the winding direction of the electrode assembly.

12. The electrode assembly according to claim 11, wherein the shape of the punch hole is circular, square, rhombus, triangular, or elliptical.

13. The electrode assembly according to claim 11, wherein the cut portion includes an arrangement of a plurality of grooves along the winding direction of the electrode assembly.

14. The electrode assembly according to claim 13, wherein the shape of the groove is circular, square, rhombic, triangular, or elliptical.

15. The electrode assembly according to claim 1, wherein an insulating coating layer is formed at the boundary between the plain area in the section where the bottom of the cutting groove and the first active material portion are separated and the first active material portion, and the distance from the bottom of the cutting groove to the cut portion is shorter than the distance from the cut portion to the insulating coating layer.

16. The electrode assembly further includes a current collector welded to a bent surface region formed by bending the plurality of segments along the radial direction of the electrode assembly, The electrode assembly according to claim 1, wherein at least a portion of the cut-off portion is provided so as to overlap with the lower region of the segment welded to the current collector.

17. The electrode assembly according to claim 16, wherein the cut portion does not intersect with a virtual line passing through the center of the upper edge and the center of the lower edge of the segment welded to the current collector.

18. The electrode assembly according to claim 1, wherein the second electrode includes a second active material portion coated with an active material layer along the winding direction, and a second plain portion not coated with an active material layer, the second plain portion includes a plurality of independently bendable segments, the plurality of segments defined as electrode tabs when bent along the radial direction of the electrode assembly, and at least a portion of the second plain portion comprising the plurality of segments includes a cut-out portion extending in one direction parallel to the winding direction.

19. The electrode assembly according to claim 18, further comprising a second current collector welded to a bent surface region formed by bending a plurality of segmental segments of the second blank portion, wherein the cut portion formed in the second blank portion is formed between the segmental segments welded to the second current collector and the second active material portion.

20. The electrode assembly according to claim 19, wherein the cut portion formed in the second blank portion does not intersect with a virtual line passing through the center of the upper edge and the center of the lower edge of the segment welded to the second current collector.

21. An electrode assembly having a core and an outer surface defined by winding a first electrode, a second electrode, and a separation membrane interposed between the first electrode and the second electrode around a winding shaft, wherein the first electrode includes a first active material portion coated with an active material layer along the winding direction, and a first blank portion not coated with an active material layer, the first blank portion being exposed to the outside of the separation membrane, the first blank portion including a plurality of independently bendable segments, the plurality of segments being defined as electrode tabs when bent along the radial direction of the electrode assembly, at least a portion of the first blank portion having the plurality of segments including a cut portion extending along one direction parallel to the winding direction, a cutting groove interposed between adjacent segments along the winding direction, the cut portion being located in the first blank portion region between the bottom of the cutting groove and the first active material portion, and the cut portion being spaced apart from the bottom of the cutting groove, A battery housing including an open end and a bottom facing the open end, wherein the electrode assembly is housed in the space between the open end and the bottom, and the battery housing is electrically connected to one of the first electrode and the second electrode and has a first polarity, A sealing body that seals the 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 second polarity with its surface exposed to the outside, Includes a battery.

22. The battery according to claim 21, wherein the sealing body includes a cap that seals the open end of the battery housing, a gasket interposed between the periphery of the cap and the open end of the battery housing, and a crimping portion that extends inward into the battery housing and is bent to wrap around and secure the periphery of the cap together with the gasket, and the terminal having the second polarity is the cap.

23. The battery according to claim 21, further comprising a first current collector welded to a bent surface region formed by bending the plurality of segmental segments of the first blank portion along the radial direction of the electrode assembly, wherein the cut portion formed in the first blank portion is formed between the segmental segments welded to the first current collector and the first active material portion.

24. The battery according to claim 23, wherein the cut portion does not intersect with a virtual line passing through the center of the upper edge and the center of the lower edge of the segment welded to the first current collector.

25. The battery according to claim 23, wherein the terminal is a rivet terminal that is insulatedly attached to a through hole formed in the bottom of the battery housing and is electrically connected to the first current collector and has the second polarity.

26. The battery according to claim 23, further comprising an insulator interposed between the inner surface of the bottom of the battery housing and the upper surface of the first current collector to electrically insulate the inner surface of the bottom of the battery housing and the first current collector.

27. The battery according to claim 21, wherein the second electrode includes a second active material portion coated with an active material layer along the winding direction and a second blank portion not coated with an active material layer, the second electrode has the first polarity, the second blank portion includes a plurality of independently bendable segmental segments, the plurality of segmental segments are defined as electrode tabs when bent along the radial direction of the electrode assembly, and at least a portion of the second blank portion having the plurality of segmental segments includes a cut-out portion extending along one direction parallel to the winding direction.

28. The battery according to claim 27, further comprising a second current collector welded to a bent surface region formed by bending a plurality of segmental segments of the second blank portion, wherein the cut portion formed in the second blank portion is formed between the segmental segments welded to the second current collector and the second active material portion.

29. The battery according to claim 28, wherein the cut portion formed in the second blank portion does not intersect with a virtual line passing through the center of the upper edge and the center of the lower edge of the segment welded to the second current collector.

30. The battery according to claim 28, wherein the battery housing includes a beading portion pushed inward from an inner wall adjacent to an open end, and at least a portion of the periphery of the second current collector is electrically connected to the beading portion.

31. The battery according to claim 30, wherein the sealing body includes a non-polarized cap whose periphery is supported by the beading portion, a gasket interposed between the periphery of the cap and the open end of the battery housing, and a crimping portion that extends inward from the open end of the battery housing and is bent to wrap around and secure the periphery of the cap together with the gasket, and at least a portion of the periphery of the second current collector is interposed and secured between the beading portion and the gasket by the crimping portion.

32. The battery according to claim 30, wherein at least a portion of the periphery of the second current collector is welded to the beading portion.

33. A battery pack comprising a plurality of batteries according to any one of claims 21 to 32.

34. The battery pack according to claim 33, wherein the ratio of the battery's height to its diameter is greater than 0.

4.

35. The battery pack according to claim 34, wherein the form factor of the battery is 46110, 4875, 48110, 4880, or 4680.

36. The battery pack according to claim 33, wherein the resistance of the battery is 4 mΩ or less.

37. The battery pack according to claim 33, wherein multiple batteries are arranged in a predetermined number of rows, and the terminals of each battery and the outer surface of the bottom of the battery housing are positioned facing upward.

38. The battery pack according to claim 37, comprising a plurality of busbars connecting a plurality of batteries in series and parallel, wherein the plurality of busbars are positioned on top of the plurality of batteries, and each busbar comprises a body portion extending between the terminals of adjacent batteries, a plurality of first busbar terminals extending to one side of the body portion and electrically coupled to the terminals of the battery located on that side, and a plurality of second busbar terminals extending to the other side of the body portion and electrically coupled to the outer surface of the bottom of the battery housing of the battery located on that side.

39. An automobile comprising the battery pack described in claim 33.

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