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

Abstract

The present invention discloses an electrode assembly, a battery, a battery pack including the same, and an automobile. 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 not coated with the active material layer, the first uncoated portion includes a plurality of segments that can be bent independently, a cut groove is interposed between the segments adjacent to each other in the winding direction, and a lower portion of the cut groove is formed of a round portion.

Description

[Technical Field]

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

[0002] This application claims priority based on Korean Patent Application No. 10-2021-0160823, filed on November 19, 2021, and the entire contents disclosed in the specification and drawings of that application are incorporated herein by reference. [Background technology]

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

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

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

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

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

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

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

[0010] 1 to 3, the positive electrode 10 and the negative electrode 11 have a structure in which an active material 21 is coated on a sheet-shaped current collector 20, and include a non-coating portion 22 on one long side along the winding direction (X-axis). The long side refers to the side that is parallel to the X-axis direction and has a relatively long length.

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

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

[0013] No separate electrode tabs are attached to the positive electrode uncoated region 10a and the negative electrode uncoated region 11a, and current collectors 30 and 31 are connected to external electrode terminals, forming a current path with a large cross-sectional area along the winding axis direction of electrode assembly A (see arrow), which has the advantage of reducing battery resistance, since resistance is inversely proportional to the cross-sectional area of ​​the path through which current flows.

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

[0015] However, when the welded regions of the non-coated portions 10a, 11a are bent, the patterns of the non-coated portions 10a, 11a may become irregularly distorted and deformed. This can cause internal short circuits due to contact with the electrode of the opposite polarity, or can lead to microcracks in the non-coated portions 10a, 11a. Furthermore, the non-coated portion 32 adjacent to the core of the electrode assembly A is bent, completely or partially blocking the cavity 33 in the core of the electrode assembly A. This can cause problems during the electrolyte injection process. The cavity 33 in the core of the electrode assembly A serves as a passage through which the electrolyte is injected. However, blocking this passage makes it difficult to inject the electrolyte. Furthermore, when an electrolyte injector is inserted into the cavity 33, it may interfere with the non-coated portion 32 near the core, resulting in tearing of the non-coated portion 32.

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

[0017] On the other hand, in a conventional table-less cylindrical battery, a positive electrode uncoated region 10a is formed over the entire top of the electrode assembly A. Therefore, when the outer periphery of the upper end of the battery housing is pressed inward to form a beading portion, the upper peripheral region 34 of the electrode assembly A is compressed by the battery housing. This compression partially deforms the electrode assembly A, which can cause the separator 12 to break and an internal short circuit. If a short circuit occurs inside the battery, it can lead to overheating or explosion of the battery. Summary of the Invention [Problem to be solved by the invention]

[0018] The present invention has been made in light of the background of the prior art described above, and aims to provide an electrode assembly having an improved uncoated portion structure that can alleviate stress applied to the uncoated portions exposed at both ends of the electrode assembly when the uncoated portions are bent.

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

[0020] Another object of the present invention is to provide an electrode assembly including a structure capable of preventing the peripheral edge of the upper end of the electrode assembly from contacting the inner surface of the battery housing when the upper end of the battery housing is beaded.

[0021] Another object of the present invention is to provide an electrode assembly in which the physical properties of the welding area are improved by applying a segment structure to the uncoated portion of the electrode and optimizing the dimensions (width, height, and spacing pitch) of the segments, thereby sufficiently increasing the number of stacked segments in the area used as the welding target area.

[0022] Another object of the present invention is to provide an electrode assembly in which cutting grooves are repeatedly formed in the uncoated portion of an electrode along the winding direction to form a plurality of segmented structures, and the lower structure of the cutting grooves is optimized to improve notching quality of the cutting grooves.

[0023] Another object of the present invention is to provide an electrode assembly in which a current collector is welded over a wide area to a folded surface region formed by folding a segment, thereby improving energy density and reducing resistance.

[0024] It is yet another object of the present invention to provide a battery including terminals and current collectors with improved designs that allow electrical wiring to be performed at the top.

[0025] It is yet another object of the present invention to provide a battery including an electrode assembly of an improved structure, a battery pack including the same, and a vehicle including the battery pack.

[0026] The technical problems that the present invention aims to solve are not limited to the above-mentioned problems, and other problems will be clearly understood by those skilled in the art from the following description of the invention. [Means for solving the problem]

[0027] In order to achieve the above object, an electrode assembly according to one aspect of the present invention is an electrode assembly in which a core and an outer circumferential surface are defined by winding a first electrode, a second electrode, and a separator interposed between the first and second electrodes 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 uncoated portion not coated with an active material layer, the first uncoated portion includes a plurality of segments that can be bent independently, a cutting groove is interposed between adjacent segments in the winding direction, and a lower portion of the cutting groove is formed by a round portion.

[0028] In one embodiment, the rounded portion may have a shape substantially the same as a circle having a diameter equal to the spacing pitch between adjacent segment pieces in the winding direction.

[0029] In another embodiment, the rounded portion may have a shape that approximately follows a circle whose diameter is equal to the spacing pitch between adjacent segment pieces in the winding direction.

[0030] In yet another embodiment, the rounded portion connects the sides of the segments located on both sides of the cutting groove, and the radius of curvature of the rounded portion may gradually increase and then gradually decrease from the side of one side segment to the side of the other side segment in a section corresponding to the separation pitch between adjacent segments in the winding direction.

[0031] The spacing pitch may be 0.05 mm to 2.0 mm, preferably 0.5 mm to 1.0 mm.

[0032] The kerfs may be formed by laser notching.

[0033] The side portions of the cut pieces located on both sides of the cutting groove may extend linearly and be connected to both ends of the rounded portion.

[0034] The upper portion of the segment may extend linearly along the winding direction, the side portions of the segment located on both sides of the cutting groove may extend linearly, and the upper corner of the segment where the upper portion and the side portion intersect may have a rounded shape.

[0035] To achieve the above object, a battery according to another aspect of the present invention 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 and second electrodes around a winding shaft, the first electrode including a first active material portion coated with an active material layer along the winding direction and a first uncoated portion not coated with the active material layer, the first uncoated portion including a plurality of segments that can be bent independently, and a wrap is formed between adjacent segments in the winding direction. a battery housing having an open end and a bottom portion opposite the open end, the battery housing housing containing the electrode assembly in a space between the open end and the bottom portion, the battery housing being electrically connected to one of the first electrode and the second electrode and having a first polarity; a sealing body sealing the open end of the battery housing; and a terminal having a second polarity and electrically connected to the other of the first electrode and the second electrode and having an exposed surface.

[0036] In one embodiment, the rounded portion may have a shape substantially the same as a circle having a diameter equal to the spacing pitch between adjacent segment pieces in the winding direction.

[0037] In another embodiment, the rounded portion may have a shape that approximately follows a circle whose diameter is equal to the spacing pitch between adjacent segment pieces in the winding direction.

[0038] In yet another embodiment, the rounded portion connects the sides of the segments located on both sides of the cutting groove, and the radius of curvature of the rounded portion may gradually increase and then gradually decrease from the side of one segment to the side of the other segment.

[0039] The core of the electrode assembly may have a cavity that is open to the outside without being blocked by the bent surface region.

[0040] The sealing body may include a cap plate that seals the open end of the battery housing, and a gasket that encloses the periphery of the cap plate and is crimped to the open end of the battery housing, and the terminal having the second polarity may be the cap plate.

[0041] The battery may further include a current collector electrically connected to the uncoated portion of the second electrode having the first polarity and having at least a portion of its periphery joined to a side wall of the battery housing, the sealing body including a cap plate with no polarity and a gasket enclosing the periphery of the cap plate and crimped to the open end of the battery housing, and the battery housing may include a rivet terminal having the second polarity, insulatively attached to a through hole formed in a center of the bottom, and electrically connected to the first electrode.

[0042] The technical object of the present invention is also achieved by a battery pack including a plurality of the above-described batteries, and a vehicle including the battery pack. [Effects of the Invention]

[0043] According to one aspect of the present invention, the uncoated portions protruding from the upper and lower sides of the electrode assembly are used as electrode tabs, thereby reducing the internal resistance of the battery and increasing the energy density.

[0044] In addition, according to one aspect of the present invention, by improving the structure of the uncoated portion of the electrode assembly, interference between the electrode assembly and the inner surface of the battery housing does not occur during the process of forming the beading portion of the battery housing, thereby preventing internal short circuits in cylindrical batteries due to partial deformation of the electrode assembly.

[0045] In addition, according to one aspect of the present invention, by improving the structure of the uncoated portion of the electrode assembly, it is possible to prevent the uncoated portion from tearing when being bent, and by sufficiently increasing the number of overlapping layers of the uncoated portion, it is possible to improve the welding strength of the current collector.

[0046] In addition, according to one aspect of the present invention, by applying a segment structure to the uncoated portion of the electrode and optimizing the dimensions (width, height, spacing pitch) of the segments, the number of segments stacked in the area used as the welding target area can be sufficiently increased, thereby improving the physical properties of the area where the current collector is welded.

[0047] In addition, according to one aspect of the present invention, when cutting grooves are repeatedly formed in the uncoated portion of the electrode along the winding direction to form a multi-piece structure, the quality of the cutting grooves can be improved by optimizing the lower structure of the cutting grooves.

[0048] Another object of the present invention is to provide an electrode assembly having improved energy density and reduced resistance by applying a structure in which a current collector is welded over a wide area to a folded surface region formed by folding a segment.

[0049] Furthermore, according to one aspect of the present invention, a cylindrical battery with an improved design that allows electrical wiring to be performed at the top can be provided.

[0050] In addition, according to one aspect of the present invention, by improving the structure of the uncoated portion adjacent to the core of the electrode assembly, it is possible to prevent the cavity in the core of the electrode assembly from being blocked when the uncoated portion is bent, and to facilitate the electrolyte injection process and the welding process between the battery housing (or terminal) and the current collector.

[0051] According to another aspect of the present invention, a cylindrical battery having a structure in which internal resistance is low, internal short circuits are prevented, and welding strength between a current collector and a non-coating portion is improved, and a battery pack and a vehicle including the same can be provided.

[0052] 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 same, and a vehicle.

[0053] The present invention also provides various other effects, which will be described later with reference to the embodiments, but explanations of effects that can be easily inferred by ordinary skilled artisans will be omitted.

[0054] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention, serve to further understand the technical concept of the present invention. Therefore, the present invention should not be interpreted as being limited to only the matters described in the drawings. [Brief explanation of the drawings]

[0055] [Figure 1] 1 is a plan view showing the structure of an electrode used in manufacturing a conventional tabless cylindrical battery. [Figure 2] 1 is a diagram showing the electrode winding process of a conventional tabless cylindrical battery. [Figure 3] 1 is a diagram showing a process of welding a current collector to a folded surface area of ​​a non-coating portion in a conventional tabless cylindrical battery. [Figure 4] 1 is a plan view showing the structure of an electrode according to an embodiment of the present invention; [Figure 5a] 10 is a diagram illustrating definitions of width, height, and spacing pitch of segments according to an embodiment of the present invention. [Figure 5b] FIG. 4 is a partially enlarged view showing the lower structure of the kerf groove according to the embodiment of the present invention. [Figure 5c]10A and 10B are diagrams illustrating how a laser irradiation pattern changes depending on the shape of the bottom of a cutting groove when a cut piece is notched with a laser according to an embodiment of the present invention. [Figure 6a] 10 is a diagram illustrating the arc formed by the lower end of a segment, which defines the width of the segment, when the electrode is wound according to an embodiment of the present invention, based on the center of the core of the electrode assembly. [Figure 6b] 10 is a diagram showing a schematic diagram of the relationship between the heights h1, h2, h3, and h4 of the segment portions, the core radius rc, and the radii r1, r2, r3, and r4 of the winding turns at which the segment portions begin to appear, according to an embodiment of the present invention. [Figure 6c] 10 is a conceptual diagram for determining the maximum value hmax for the height H of a segment in a segment height variable section. FIG. [Figure 6d] FIG. 10 is a schematic diagram for explaining the formula for determining the lower interior angle θ of a segment. [Figure 7a] FIG. 10 is a plan view showing an electrode structure according to another embodiment of the present invention. [Figure 7b] 7b is a top view showing the independent regions where the plurality of segmented pieces are located when the electrode shown in FIG. 7a is wound into an electrode assembly. FIG. [Figure 8a] FIG. 10 is a plan view showing the structure of an electrode according to another embodiment of the present invention. [Figure 8b] 10 is a diagram illustrating definitions of width, height, and spacing pitch of segments according to another embodiment of the present invention. [Figure 8c] FIG. 10 is a partially enlarged view showing a lower structure of a kerf groove according to another embodiment of the present invention. [Figure 8d] FIG. 10 is a plan view showing an electrode structure according to still another embodiment of the present invention. [Figure 9] 10A to 10C are diagrams illustrating various modified examples of segmented structures according to the present invention; [Figure 10a] 4 is a schematic diagram illustrating a cross section of a bent surface region formed by bending a segment toward a core of an electrode assembly according to an embodiment of the present invention; [Figure 10b] 1 is a top perspective view schematically illustrating an electrode assembly having a folded surface region formed thereon according to an embodiment of the present invention; [Figure 11a] 10 is a graph showing the results of counting the number of stacked pieces along the radial direction in the folded surface region of the positive electrode formed on the upper part of the electrode assemblies according to Examples 1-1 to 1-7 and a comparative example. [Figure 11b] 10 is a graph showing the results of counting the number of stacked pieces measured along the radial direction in the folded surface region of the positive electrode formed on the upper part of the electrode assembly 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 11c] 10 is a graph showing the results of counting the number of stacked pieces measured along the radial direction in the folded surface region of the positive electrode formed on the upper part of the electrode assemblies according to Examples 6-1 to 6-6 and 7-1 to 7-6. [Figure 12] 1 is a top view of an electrode assembly showing a uniform lamination number section b1 and a reduced lamination number section b2 in a folded surface region of a segment according to an embodiment of the present invention. [Figure 13] 1 is a cross-sectional view of a jelly-roll type electrode assembly according to an embodiment of the present invention, taken along the Y-axis direction (winding axis direction). [Figure 14] 10 is a cross-sectional view of a jelly-roll type electrode assembly according to another embodiment of the present invention, taken along the Y-axis direction (winding axis direction). FIG. [Figure 15] 10 is a cross-sectional view of a jelly-roll type electrode assembly according to yet another embodiment of the present invention, taken along the Y-axis direction (winding axis direction). FIG. [Figure 16] 10 is a cross-sectional view of a jelly-roll type electrode assembly according to yet another embodiment of the present invention, taken along the Y-axis direction (winding axis direction). FIG. [Figure 17] 1 is a cross-sectional view of a cylindrical battery according to an embodiment of the present invention taken along a Y-axis direction. [Figure 18] 4 is a cross-sectional view of a cylindrical battery according to another embodiment of the present invention taken along the Y-axis direction. FIG. [Figure 19] 10 is a cross-sectional view of a cylindrical battery according to yet another embodiment of the present invention, taken along the Y-axis direction. [Figure 20]10 is a cross-sectional view of a cylindrical battery according to yet another embodiment of the present invention, taken along the Y-axis direction. [Figure 21] FIG. 3 is a top view showing the structure of a first current collector plate according to an embodiment of the present invention. [Figure 22] FIG. 4 is a perspective view showing the structure of a second current collecting plate according to an embodiment of the present invention. [Figure 23] FIG. 10 is a top view showing a state in which a plurality of cylindrical batteries are electrically connected. [Figure 24] FIG. 24 is a partially enlarged view of FIG. 23. [Figure 25] 1 is a diagram illustrating a schematic configuration of a battery pack according to an embodiment of the present invention; [Figure 26] 1 is a schematic diagram of a vehicle including a battery pack according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0056] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and phrases used in the specification and claims should not be construed as being limited to their ordinary and dictionary meanings, but should be construed as having meanings and concepts corresponding to the technical ideas of the present invention, in accordance with the principle that the inventors themselves can appropriately define the concepts of terms in order to best describe the invention.

[0057] Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent the entire technical idea of ​​the present invention, and that there may be various equivalents and modifications that can be substituted therefor at the time of this application.

[0058] In addition, to facilitate understanding of the invention, the accompanying drawings may not be drawn to scale, and the dimensions of some components may be exaggerated. In addition, the same reference numerals may be used to refer to the same components in different embodiments.

[0059] The expression that two comparison objects are identical means that they are "substantially identical." Therefore, "substantially identical" may include deviations that are considered low in the art, for example, deviations within 5%. Furthermore, the expression that a parameter is uniform in a given region means that the parameter is uniform on average in that region.

[0060] Furthermore, although terms such as "first" and "second" are used to indicate various components, these terms are not intended to limit the components. These terms are used merely to distinguish one component from another, and unless otherwise specified, the first component can also be the second component.

[0061] Throughout the specification, unless otherwise stated, each element may be singular or plural.

[0062] When an arbitrary structure is disposed "on (or under)" a component or "above (or below)" a component, it means not only that the arbitrary structure is disposed in contact with the upper surface (or lower surface) of the component, but also that other structures may be interposed between the component and the arbitrary structure disposed above (or below) the component.

[0063] Furthermore, when a component is referred to as being "coupled," "coupled," or "connected" to another component, it does not only mean that the components are directly coupled or connected to each other, but also that other components are "interposed" between the components, or that each component is "coupled," "coupled," or "connected" through other components.

[0064] Throughout the specification, unless otherwise specified, "A and / or B" means A, B, or A and B, and "C to D" means C or more and D or less, unless otherwise specified.

[0065] For ease of explanation, in this specification, the direction along the length of the winding shaft of the electrode assembly wound into a jelly roll is referred to as the axial direction (Y-axis). The direction surrounding the winding shaft is referred to as the circumferential direction or outer circumferential direction (X-axis). The direction toward or away from the winding shaft is referred to as the radial direction. Of these, the direction toward the winding shaft is particularly referred to as the centripetal direction, and the direction away from the winding shaft is particularly referred to as the centrifugal direction.

[0066] First, an electrode assembly according to an 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 sheet-like second electrode, and a separator interposed between the first and second electrodes are wound in one direction. However, the present invention is not limited by the type of electrode assembly.

[0067] Preferably, at least one of the first and second electrodes includes an uncoated portion on a long side edge in the winding direction where no active material is coated. At least a portion of the uncoated portion itself is used as an electrode tab. The uncoated portions include a core-side uncoated portion adjacent to the core of the electrode assembly, an outer-side uncoated portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate uncoated portion interposed between the core-side uncoated portion and the outer-side uncoated portion.

[0068] Preferably, at least one of the core-side uncoated portion and the outer-periphery-side uncoated portion has a height relatively lower than that of the intermediate uncoated portion.

[0069] FIG. 4 is a plan view showing the structure of an electrode 60 according to one embodiment of the present invention.

[0070] Referring to FIG. 4, an electrode 60 according to an embodiment includes a current collector 41 made of metal foil and an active material layer 42. The metal foil may be made of a conductive metal, such as aluminum or copper, and is appropriately selected depending on the polarity of the electrode 60. 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 60 includes a non-coated portion 43 at the end of a long side in the winding direction (X-axis). The non-coated portion 43 is a portion of the current collector 41 that is not coated with an active material. The region of the current collector 41 on which the active material layer 42 is formed may be referred to as the active material portion.

[0071] In electrode 60, the width of the active material portion in the direction of the short sides of current collector 41 may be 50 mm to 120 mm, and the length of the active material portion in the direction of the long sides of current collector 41 may be 3 m to 5 m. Therefore, the ratio of the short sides to the long sides of the active material portion may be 1.0% to 4.0%.

[0072] Preferably, in electrode 60, the width of the active material portion in the direction of the short sides of current collector 41 may be 60 mm to 70 mm, and the length of the active material portion in the direction of the long sides of current collector 41 may be 3 m to 5 m. Therefore, the ratio of the short sides to the long sides of the active material portion may be 1.2% to 2.3%.

[0073] The ratio of the short side to the long side of the active material portion is significantly smaller than the 6% to 11% ratio of the long side to the short side of the active material portion of electrodes used in cylindrical batteries having 1865 or 2170 form factors.

[0074] Preferably, an insulating coating layer 44 may be formed at the boundary between the active material layer 42 and the uncoated portion 43. The insulating coating layer 44 is formed so that at least a portion thereof overlaps the boundary between the active material layer 42 and the uncoated portion 43. The insulating coating layer 44 prevents short-circuiting between two electrodes of opposite polarity facing each other via a separator. The insulating coating layer 44 may cover the boundary between the active material layer 42 and the uncoated 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 60. The insulating coating layer 44 includes a polymer resin and may also include an inorganic filler such as SiO2 or Al2O3. The portion of the current collector 41 covered by the insulating coating layer 44 may be considered an uncoated portion because it is not a region coated with an active material layer.

[0075] The uncoated portion 43 includes a core-side uncoated portion B1 adjacent to the core side of the electrode assembly, an outer-periphery-side uncoated portion B3 adjacent to the outer periphery side of the electrode assembly, and an intermediate uncoated portion B2 interposed between the core-side uncoated portion B1 and the outer-periphery-side uncoated portion B3.

[0076] The core-side uncoated area B1, the outer-periphery-side uncoated area B3, and the middle uncoated area B2 can be defined as the uncoated area adjacent to the core side, the uncoated area adjacent to the outer periphery, and the uncoated area excluding these, respectively, when the electrode 60 is wound into a jelly roll-type electrode assembly.

[0077] Hereinafter, the core-side uncoated portion B1, the outer-periphery-side uncoated portion B3, and the middle uncoated portion B2 will be referred to as the first portion, the second portion, and the third portion, respectively.

[0078] For example, the first portion B1 may be an uncoated portion of the electrode area including the innermost winding turn, and the second portion B3 may be an uncoated portion of the electrode area including the outermost winding turn. The winding turns may be counted relative to the core end of the electrode assembly.

[0079] As another example, the B1 / B2 boundary may be appropriately defined at a point where the height (or change pattern) of the uncoated portion substantially changes from the core side to the outer periphery side of the electrode assembly, or at a point that is a predetermined percentage based on the radius of the electrode assembly (e.g., 5%, 10%, 15% of the radius, etc.).

[0080] The B2 / B3 boundary may be defined as a point where the height (or variation pattern) of the uncoated portion substantially changes from the outer periphery side to the core side of the electrode assembly, or a point at a predetermined percentage of the radius of the electrode assembly (e.g., 85%, 90%, 95% of the radius, etc.). Once the B1 / B2 boundary and the B2 / B3 boundary are identified, the third portion B2 may be automatically identified.

[0081] If only the B1 / B2 boundary is specified, the B2 / B3 boundary can be appropriately selected at a point near the outer periphery of the electrode assembly. For example, the second portion can be defined as the uncoated portion of the electrode region that constitutes 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 B1 can be defined as the uncoated portion of the electrode region that constitutes the innermost winding turn.

[0082] It is not excluded that another structure is interposed between the first portion B1 and the third portion B2, and it is also not excluded that another structure is interposed between the third portion B2 and the second portion B3.

[0083] The height of the non-coating portion 43 is not constant but varies relative to the winding direction (X-axis). That is, the height (length in the Y-axis direction) of the second portion B3 is greater than or equal to 0 and is relatively shorter than the first portion B1 and the third portion B2. Here, the height of each portion may be an average height or a maximum height, and the same applies below. In the winding direction, the length of the third portion B2 is longer than the first portion B1 and the second portion B3.

[0084] The electrode 60 has a first portion B1 and a second portion B3 whose heights are equal to or greater than 0 and are relatively lower than the third portion B2. The heights of the first portion B1 and the second portion B3 may be the same or different.

[0085] Width d of the first portion B1 B1 The third part B2 is designed so that the core of the electrode assembly is not blocked when the uncoated portion of the third part B2 is bent toward the core. The core refers to the cavity present at the center of the winding of the electrode assembly.

[0086] As an example, the width d of the first portion B1 B1 can increase in proportion to the folded length of the plain portion closest to the core.

[0087] Preferably, the width d of the first portion B1 B1 The width d of the first portion B1 may be set so that the radial width of the wound turn formed by the first portion B1 is equal to or greater than the bending length of the uncoated area closest to the core. B1 can be set so that the value obtained by subtracting the radial width of the wound turn formed by the first portion B1 from the folded length of the uncoated region closest to the core is less than 0 or 10% or less of the core radius.

[0088] In a specific example, when the electrode 60 is used to manufacture an electrode assembly for a cylindrical battery with a form factor of 4680, the width d of the first portion B1 is B1 can be set to 180 mm to 350 mm depending on the diameter of the core of the electrode assembly and the bent length of the uncoated area closest to the core.

[0089] At least a portion of the uncoated portion of the third portion B2 may include a plurality of divisional segments 61. The divisional segments 61 may have heights that increase stepwise from the core side to the outer periphery. Alternatively, the divisional segments 61 may have the same height from the core side to the outer periphery. The divisional segments 61 have a geometric shape whose width decreases from bottom to top. Preferably, the geometric shape is a trapezoid. As will be described later, the geometric shape may be variously modified, such as a rectangle or a parallelogram.

[0090] The section 61 may be laser notched. The section 61 may be formed by known metal foil cutting processes such as ultrasonic cutting or punching.

[0091] To prevent damage to the active material layer 42 and / or the insulating coating layer 44 during the folding process of the uncoated portion 43, it is preferable to provide a predetermined gap between the lower end of the cut groove (G in FIG. 5a) between the adjacent cut pieces 61 and the active material layer 42. This is because stress is concentrated near the lower end of the cut groove 63 when the uncoated portion 43 is folded. The gap may vary along the winding direction of the electrode 60. The gap is preferably 0.2 mm to 4 mm, and more preferably 1.5 mm to 2.5 mm. Adjusting the gap within the above numerical range prevents damage to the active material layer 42 and / or the insulating coating layer 44 near the lower end of the cut groove 63 due to stress generated during the folding process of the uncoated portion 43. Furthermore, the gap prevents damage to the active material layer 42 and / or the insulating coating layer 44 due to tolerances during notching or cutting the cut pieces 61. In one direction parallel to the winding direction, the gap may be substantially constant or may vary. In the latter case, the gap between the plurality of segments may vary individually, in groups, or in groups of two or more groups along a direction parallel to the winding direction. The lower ends of the cut grooves 63 and the insulating coating layer 44 may be spaced apart by 0.5 mm to 2.0 mm. The distance between the lower ends of the cut grooves 63 and the insulating coating layer 44 along a direction parallel to the winding direction may be substantially uniform or may vary. In the latter case, the gap between the plurality of segments may vary individually, in groups, or in groups of two or more groups along a direction parallel to the winding direction. When the electrode 60 is wound, the end of the insulating coating layer 44 in the winding axis (Y-axis) direction may be located within a range of -2 mm to 2 mm along the winding axis direction from the end of the separator. The insulating coating layer 44 prevents short-circuiting between two electrodes of opposite polarity facing each other across the separator and supports the bending point when the segment 61 is bent. To improve the effect of preventing short circuits between the two electrodes, the insulating coating layer 44 may be exposed to the outside of the separator. Also, to further maximize the effect of preventing short circuits 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 winding axis (Y-axis) direction is positioned above the lower end 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 from the lower end 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 separator.

[0092] In one embodiment, the plurality of segment pieces 61 may be arranged in a plurality of segment groups from the core side toward the outer periphery side. At least one of the width, height, and spacing pitch of the segment pieces belonging to the same segment group may be substantially the same. Preferably, the width, height, and spacing pitch of the segment pieces belonging to the same segment group may be the same.

[0093] Preferably, the width and height of the segments belonging to the same segment group may be substantially the same.

[0094] In another embodiment, the spacing pitch of the plurality of segments may increase gradually or stepwise from the core side to the outer periphery side, in groups or in groups of two or more, or vice versa.

[0095] In yet another embodiment, the spacing pitch of the multiple segments may be such that, in groups or in groups of two or more, the spacing pitch gradually or stepwise increases from the core side to the outer periphery side and then gradually or stepwise decreases, or vice versa.

[0096] In yet another embodiment, the gap between the lower end of the cutting groove 63 and the insulating coating layer 44 or the active material layer 42 of the multiple cut pieces may increase gradually or stepwise from the core side to the outer periphery side, or vice versa.

[0097] In still another embodiment, the gap between the lower end of the cutting groove 63 and the insulating coating layer 44 or the active material layer 42 of the plurality of cut pieces may gradually or stepwise increase or decrease from the core side to the outer periphery side, or vice versa.

[0098] FIG. 5a is a diagram showing the definitions of the width D, height H and spacing pitch P of the trapezoidal segment pieces 61, and FIG. 5b is a partially enlarged view showing the lower part of the cutting groove 63.

[0099] 5a and 5b, the width D, height H, and spacing pitch P of the divided pieces 61 are designed to prevent tearing of the uncoated portion 43 near the bending point during bending and to ensure sufficient welding strength by sufficiently increasing the number of overlapping layers of the uncoated portion 43 while preventing abnormal deformation of the uncoated portion 43.

[0100] The bending of the segment 61 is performed along or above a line G passing through the lower end of the cutting groove 63. The cutting groove 63 allows the segment 61 to be smoothly and easily bent in the radial direction of the electrode assembly.

[0101] The cutting groove 63 has two segments 61 arranged on both sides thereof. The cutting groove 63 includes a side portion 63a and a round portion 63b of the segment 61. The side portion 63a extends linearly. The side portion 63a forms an acute angle with the winding direction. The round portion 63b may have a radius of curvature. Both ends of the round portion 63b are smoothly connected to the side portion 63a.

[0102] The width D of the portion 61 is defined as the length between two points where two straight lines extending from the side portion 63a of the portion 61 intersect with a straight line G extending in the winding direction through the lower end of the round portion 63b.

[0103] The height H of the portion segment 61 is defined as the shortest distance between the uppermost edge of the portion segment 61 and a straight line that passes through the lower end of the round portion 63b and extends in the winding direction.

[0104] 5b, the separation pitch P of the segment pieces 61 is defined as the length between two points where a straight line L1 connecting both end portions of the rounded portion 63b intersects with a straight line L2 extending from both side portions 63a of the cutting groove 63. In other words, the separation pitch P corresponds to the distance between two points where the radius of curvature begins to change at the bottom of the side portions 63a on both sides of the cutting groove 63.

[0105] The spacing pitch P of the segment pieces 61 may be 0.05 mm to 2.0 mm, and preferably 0.5 mm to 1.0 mm.

[0106] The rounded portion 63b may be substantially identical to a circle whose diameter is the separation pitch P. Alternatively, the rounded portion 63b may approximately follow the pattern of a circle whose diameter is the separation pitch P. Alternatively, the rounded portion 63b may connect the sides of the segment pieces 61 located on either side of the cutting groove 63, and the radius of curvature of the rounded portion 63b may gradually increase and then gradually decrease from the side of one segment piece 61 to the side of the other segment piece 61.

[0107] If a round portion 63b that is substantially identical to a circle having a diameter equal to the spacing pitch P, a round portion 63b that approximately follows the circle, or a round portion 63b whose radius of curvature gradually increases and then gradually decreases is provided at the bottom of the cutting groove 63, the notching quality can be improved during the notching process of the divided pieces 61.

[0108] In an embodiment of the present invention, the rounded portion 63b approximately follows a circle means that the radius of curvature of the rounded portion 63b gradually changes within a range of 20% based on the radius of a circle whose diameter is the separation pitch P, smoothly connecting the lower ends of the side portions 63a on both sides of the cutting groove 63.

[0109] 5c shows the results of a laser notching experiment, showing how the laser irradiation pattern changes depending on the shape of the bottom of the cutting groove 63 when notching a section 61 with a laser.

[0110] In the notching experiment, instead of a current collector foil, a thick copper plate was irradiated with a notching laser according to the shape of the section 61. The reason for using a copper plate was to observe the irradiation pattern of the notching laser.

[0111] The notching speed of a laser notching device slows down when the radius of curvature of the notching pattern changes suddenly. In other words, the irradiation interval of the notching laser becomes shorter in areas where the radius of curvature changes suddenly. This is because when the device that irradiates the notching laser passes through an area where the radius of curvature changes suddenly, the moving speed of the device is relatively slower than in areas where a linear pattern is notched, due to the precision of the notching process.

[0112] The plain portions of the electrodes processed using the notching patterns in Experiment (a) and Experiment (b) had the same spacing pitch of 0.5 mm between the segment pieces 61. That is, in Experiments (a) and (b), the side portions 63a of the segment pieces 61 located on both sides of the cutting groove 63 were the same, and the notching conditions were set so that only the pattern on the bottom of the cutting groove 63 connecting the ends of the side portions 63a was different. In Experiment (b), the radius of curvature of the rounded portion 63b was 1 / 2 (0.25 mm) of the spacing pitch.

[0113] Similarly, the plain portions of the electrodes processed using the notching patterns in Experiments (c) and (d) had the same spacing pitch of 1.0 mm between the segment pieces 61. That is, in Experiments (c) and (d), the side portions 63a of the segment pieces 61 located on both sides of the cutting groove 63 were identical, and the notching conditions were set so that only the pattern on the bottom of the cutting groove 63 connecting the ends of the side portions 63a was different. In Experiment (d), the radius of curvature of the rounded portion 63b was 1 / 2 (0.5 mm) of the spacing pitch.

[0114] Looking at the notching patterns in Experiments (a) and (c), the curvature changes abruptly in the region corresponding to the bottom corner of the kerf 63. That is, the notching pattern for forming the bottom of the kerf 63 includes a linear side section, a corner section with a small radius of curvature, and a linear bottom section. As a result, the notching speed significantly decreases at the bottom of the kerf 63, and the laser irradiation points continuously overlap.

[0115] On the other hand, the notching patterns in Experiments (b) and (d) have smooth notching patterns to form rounded portions 63b at the bottom of the kerf 63, and therefore do not have any corner structures with abrupt changes in the radius of curvature. As a result, the notching speed at the bottom of the kerf 63 does not decrease as significantly as in Experiments (a) and (c), and there are no sections where the laser irradiation points continuously overlap.

[0116] For reference, the experimental results in FIG. 5c also show data on the length of each notching section and the notching speed.

[0117] According to Experiments (a) and (c), the radius of curvature of the notching pattern for forming the lower part of the kerf 63, particularly the corner part, changes suddenly. As a result, the laser notching speed decreases in the notching region corresponding to the lower part of the kerf 63, and the laser irradiation patterns essentially overlap.

[0118] In fact, when a laser is irradiated onto a current collector foil according to the notching patterns shown in Experiments (a) and (c), heat accumulates in the area where the notching laser overlaps. As a result, when the current collector foil is detached along the notching pattern, the current collector foil does not detach locally at the bottom of the cut groove 63 or at the side 63a of the cut piece 61 in the vicinity thereof, or even if the foil detaches, the detached point becomes bent, resulting in defects.

[0119] Meanwhile, when a laser is irradiated onto an actual current collector foil according to the notch patterns shown in Experiments (b) and (d), no continuous overlapping regions of the notching laser are formed. As a result, when the current collector foil is detached along the notch pattern, the current collector foil is not locally detached from the side 63a of the divided piece 61, or defects such as bending of the detached portion do not occur.

[0120] 5a, preferably, the width D of the divided pieces 61 is 1 mm or more. If D is less than 1 mm, when the divided pieces 61 are bent toward the core, the divided pieces 61 may not overlap to an extent that sufficient welding strength can be ensured, or empty spaces (gaps) may occur.

[0121] Preferably, the width D of the segment 61 can be adaptively adjusted according to the radius of the winding turn on which the segment 61 is located so that the segment 61 can easily overlap radially when the segment 61 is bent toward the core side of the electrode assembly.

[0122] 6a shows the bottom end of the electrode segment 61 (line segment D in FIG. 5a) that defines the width D of the electrode segment 60 when the electrode 60 is wound according to an embodiment of the present invention. ab ) is a diagram showing the arc A1A2 formed by the center O of the core of the electrode assembly as a reference.

[0123] 6a, arc A1A2 has a length corresponding to width D of segment 61 and has a circumferential angle Φ relative to the center of the core of the electrode assembly. Circumferential angle Φ can be defined as the angle between two line segments connecting both ends of arc A1A2 and center O of the core on a plane perpendicular to the winding axis and passing through arc A1A2.

[0124] When the length of the arc A1A2 of the minute segment 61 is the same, the inclination angle Φ decreases as the radius r of the winding turn on which the minute segment 61 is located increases. Conversely, when the inclination angle Φ of the minute segment 61 is the same, the length of the arc A1A2 increases proportionally as the radius r of the winding turn on which the minute segment 61 is located increases.

[0125] The inclination angle Φ affects the bending quality of the segment 61. In the drawing, the solid arrow indicates the direction of the force applied to bend the segment 61, and the dotted arrow indicates the direction in which the segment 61 is bent. The bending direction is toward the center O of the core.

[0126] The circumferential angle Φ of the segment 61 may be 45° or less, preferably 30° or less, depending on the radius r of the winding turn where the segment 61 is located, in order to improve the uniformity of the folding and prevent the occurrence of cracks.

[0127] In one embodiment, the circumferential angle Φ of the segment 61 may increase or decrease gradually or stepwise along the radial direction of the electrode assembly within the above numerical range. In another embodiment, the circumferential angle Φ of the segment 61 may increase gradually or stepwise and then decrease gradually or stepwise along the radial direction of the electrode assembly within the above numerical range, or vice versa. In yet another embodiment, the circumferential angle Φ of the segment 61 may be substantially constant along the radial direction of the electrode assembly within the above numerical range.

[0128] Experiments have shown that if the circumferential angle Φ of the segment 61 exceeds 45°, the folding pattern of the segment 61 will not be uniform. The difference in force applied to the center and side edges of the segment 61 will increase, causing the segment 61 to be pressed unevenly in the circumferential direction. Furthermore, if the pressing force is increased to ensure uniform folding, cracks may occur in the plain portion 43 near the cut grooves 63.

[0129] In one example, the circular angles Φ of the segments 61 included in the electrode 60 may be substantially identical, and the widths of the segments 61 may increase proportionally as the radius r of the winding turn on which the segments 61 are located increases. "Substantially identical" means either completely identical or with a deviation of less than 5%.

[0130] For example, when the radius of the electrode assembly is 22 mm, the radius of the core is 4 mm, and the segment 61 is disposed from a winding turn located at a radius of 7 mm, if the inclination angle Φ of the segment 61 is constant at 28.6°, the width D of the segment 61 may increase proportionally depending on the radius r of the winding turn on which the segment 61 is located, as shown in Table 1 below. That is, the width of the segment 61 may increase by 0.5 mm at substantially the same rate for every 1 mm increase in the radius r of the winding turn.

[0131] [Table 1]

[0132] Preferably, the width D(r) of the segment 61 located on the winding turn having a radius r based on the center O of the core of the electrode assembly can be determined within a range that satisfies the following Equation 1.

[0133] [Formula 1] 1≦D(r)≦(2×π×r / 360°)×45°

[0134] Preferably, each of the plurality of segments 61 has a width D(r) in the winding direction that gradually or stepwise increases as the radius r of the winding turn in which the segment 61 is located increases relative to the center of the core of the electrode assembly, or vice versa.

[0135] In another embodiment, each of the plurality of segments 61 may have a width D(r) in the winding direction that gradually or stepwise increases 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 relative to the center of the core of the electrode assembly, or vice versa.

[0136] In yet another embodiment, each of the plurality of segments 61 may have a width D(r) in the winding direction that gradually or stepwise increases and then gradually or stepwise decreases as the radius r of the winding turn in which the segment 61 is located increases relative to the center of the core of the electrode assembly, or vice versa.

[0137] In yet another embodiment, each of the plurality of segments 61 may have a width D(r) in the winding direction 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 segment 61 is located increases relative to the center of the core of the electrode assembly, or vice versa.

[0138] In still 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 can be the same or different.

[0139] In still other embodiments, the rate at which the width D(r) of the segment 61 changes from 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.

[0140] 5a, the height H of the divided pieces 61 may be 2 mm or more. If D2 is less than 2 mm, when the divided pieces 61 are bent toward the core, the divided pieces 61 may not overlap to an extent that sufficient welding strength can be ensured, or empty spaces (gaps) may occur.

[0141] The height H of the segment 61 can be determined by applying the condition that the segment 61 does not block the core when bent toward the core. Preferably, the height H of the segment 61 can be adjusted so that 90% or more of the diameter of the core is open to the outside.

[0142] Preferably, the height H of the segment 61 may gradually increase from the core side to the outer periphery side depending on the radius of the winding turn on which the segment 61 is located and the radius of the core.

[0143] In one example, the height H of the segment 61 increases from h1 to h2 as the radius of the winding turn increases. N If the height is increased stepwise over N steps up to the k-th height h of the segment 61, k (k is a natural number between 1 and N), height h kThe starting radius of the winding turn containing the segment 61 is r k , the radius of the core is r c Then, the heights h1 to h2 of the segment 61 are determined so that the following formula 2 is satisfied. N can be determined.

[0144] [Formula 2] 2mm≦h k ≦r k -α×r c (Preferably, α is 0.90 to 1)

[0145] The height of the segment 61 h k If formula 2 is satisfied, even if the segment 61 is bent toward the core, 90% or more of the diameter of the core can be opened to the outside.

[0146] For example, if the radius of the entire winding turn of the electrode assembly is 22 mm, the height of the sub-segment 61 starts at 3 mm, and as the radius of the winding turn including the sub-segment 61 increases by 1 mm, the height of the sub-segment 61 increases in order from 3 mm to 4 mm, 5 mm, and 6 mm, while the height of the remaining winding turns remains substantially constant at 6 mm. That is, the radial width of the height-variable section of the sub-segment 61 within the radius of the entire winding turn is 3 mm, and the remaining radius sections correspond to uniform height sections.

[0147] In this case, the radius r of the core of the electrode assembly c The starting radii r1, r2, r3, r4 of the winding turn including the segment 61 having heights of 3 mm, 4 mm, 5 mm, and 6 mm according to the above are as shown in Table 2 below when α is 1 and the equality condition is applied in the inequality on the right.

[0148] [Table 2]

[0149] When the segment 61 is positioned at the radial position shown in Table 2, the segment 61 will not block the core even if it is bent toward the core. On the other hand, r1, r2, r3, and r4 shown in Table 2 can be shifted toward the core depending on the α value. In one example, when α is 0.90, r1, r2, r3, and r4 can be shifted toward the core by 10% of the core radius. In this case, when the segment 61 is bent toward the core, 10% of the core radius is blocked by the segment 61. r1, r2, r3, and r4 shown in Table 2 are limit values ​​for the position where the segment 61 starts. Therefore, the position of the segment 61 can be shifted a predetermined distance toward the outer periphery from the radius shown in Table 2. Figure 6b shows the relationship between the heights h1, h2, h3, and h4 of the segment 61 and the core radius r c 10 is a diagram showing a schematic diagram of the relationship between the radii r1, r2, r3, and r3 of the winding turns at which the winding segment 61 begins to appear.

[0150] Referring to Table 2 and FIG. 6b, for example, the radius r of the core C c When the value of α in Equation 2 is 3 mm, the starting radii r1, r2, r3, and r4 of the winding turn including the segment 61 with heights of 3 mm (h1), 4 mm (h2), 5 mm (h3), and 6 mm (h4) may be 6 mm, 7 mm, 8 mm, and 9 mm, respectively, and the height of the segment 61 may be maintained at 6 mm from the radius of 9 mm to the last winding turn. Furthermore, the segment 61 may not be included in a winding turn having a radius smaller than 6 mm (r1). In this example, the segment 61 with a height of 3 mm (h1) closest to the core C is located from the winding turn with a radius of 6 mm. Therefore, even if the segment 61 is bent toward the core C, it only covers the radius section from 3 mm to 6 mm, and does not substantially block the core C. The position of the segment 61 is determined by the value of α in Equation 2, depending on the core radius r. c can be shifted to the core C side within 10% of the

[0151] In other embodiments, the height of the segment 61 may increase at the same or different rates as the starting radius r of the winding turn in which the segment 61 is located increases relative to the center of the core of the electrode assembly.

[0152] Preferably, the height H of the segment 61 satisfies the formula 2, and the maximum height of the segment 61 can be limited.

[0153] FIG. 6c shows the maximum value h of the height H of the segment 61 in the height variable section of the segment 61. max FIG. 1 is a conceptual diagram for determining

[0154] Referring to FIG. 6c, in the wound structure of the electrode assembly, an electrode E1 including a segment 61 faces an electrode E2 of the opposite polarity in the radial direction with a separator S interposed therebetween. 1,active is coated on both sides of the electrode E2, and an active material layer E 2,active For electrical insulation, the edge S of the separation membrane S is coated end is the end E of electrode E2 2,end From the insulation gap W gap The end of electrode E1 may extend further outward by a length corresponding to the length of electrode E2. In addition, the end of electrode E1 does not extend further outward than the end of electrode E2 due to electrical insulation. Therefore, an insulating gap W is formed at the lower end of uncoated portion 43. gap In addition, when the electrodes E1 and E2 and the separator S are wound up, the end S of the separator S must be secured. end Therefore, in order for the segment 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 margin,min must be allocated to the plain portion 43. In addition, in order to cut the cut pieces 61, a minimum cutting scrap margin W must be provided at the end of the current collector foil. scrap,min Therefore, the maximum height h of the segment 61 must be max can be determined by the following equation 3: foil corresponds to the width of the current collector foil before it is cut.

[0155] [Formula 3] h max =W foil -W scrap,min -W margin,min -W gap

[0156] Preferably, the insulating gap W gap When the first electrode is a positive electrode, the insulating gap W may be 0.2 mm to 6 mm. gap When the first electrode is a negative electrode, the thickness may be 0.1 mm to 2 mm.

[0157] Preferably, the cutting minimum scrap margin W scrap,min The minimum cutting scrap margin W can be 1.5mm to 8mm. scrap,min may not be assigned depending on the process of forming the divided piece 61. For example, the cutting groove 63 may be formed so that the upper edge of the divided piece 61 coincides with the upper edge of the current collector foil. In this case, in Equation 3, W scrap,min can be 0.

[0158] Preferably, the minimum meandering margin W of the separation membrane margin,min can be 0 to 1 mm.

[0159] As an example, the minimum cutting scrap margin W scrap,min is 1.5 mm, and the minimum meandering margin W of the separation membrane S margin,min Under these conditions, the width W of the current collector foil before forming the divided pieces 61 may be 0.5 mm. foil is 8mm~12mm, and the insulation gap W gap When is 0.6 mm, 0.8 mm, and 1.0 mm, the maximum height h of the segment 61 is calculated using Equation 3. max The calculation results are shown in Table 3 below.

[0160] [Table 3]

[0161] Referring to Table 3, the maximum height h of the segment 61 in the height variable section of the segment 61 is maxmay 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 may increase stepwise or gradually in the radial direction of the electrode assembly from 2 mm to 10 mm. Further referring to FIG. 5a, the separation pitch P of the segment 61 may be adjusted in the range of 0.05 to 2 mm, preferably 0.5 to 1.0 mm. If the separation pitch P is less than 0.05 mm, stress may cause cracks in the uncoated portion 43 near the bottom of the cut groove 63 when the electrode 60 travels during a winding process or the like. On the other hand, if the separation pitch P exceeds 2 mm, when the segment 61 is bent, the segment 61 may not overlap to an extent sufficient to ensure sufficient welding strength, or empty spaces (gaps) may be generated.

[0162] 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 during a winding process or the like, it is possible to prevent cracks from occurring below the cutting grooves 63.

[0163] According to the experimental results, when the current collector 41 of the electrode 60 is an aluminum foil having a thickness of 15 μm and the separation pitch P is 0.5 mm or more, no cracks occur below the cutting groove 63 when the electrode 60 runs under the running conditions described above.

[0164] The lower interior angle θ of the plurality of segment pieces 61 may increase from the core side toward the outer periphery. As an example, the lower interior angle θ of the plurality of segment pieces 61 may increase gradually or in steps from the core side toward the outer periphery. The lower interior angle θ is the angle between a line extending from the lower end of the cutting groove 63 and a line extending from the side portion 63a of the segment piece 61. When the segment piece 61 is bilaterally symmetrical, the lower interior angle θ on the left and right sides is substantially the same.

[0165] As the radius of the electrode assembly increases, the radius of curvature also increases. If the lower interior angle θ of the segment 61 increases with the radius of the electrode assembly, stresses occurring in the radial and circumferential directions when the segment 61 is bent can be alleviated. Furthermore, as the lower interior angle θ increases, the overlapping area with the inner segment 61 and the number of overlapping layers also increase when the segment 61 is bent, ensuring uniform welding strength in the radial and circumferential directions and enabling the bent surface area to be formed flat.

[0166] Preferably, the lower interior angle θ can be determined by the radius of the winding turn on which the segment 61 is located and the width D of the segment 61.

[0167] FIG. 6d is a schematic diagram for explaining the formula for determining the lower interior angle θ of the segment 61.

[0168] Referring to FIG. 6d, ideally, the sides of the segment 61 coincide with the line segments AE and DE, which connect the ends A and D of the line segment AD corresponding to the width D of the segment 61 to the center E of the core.

[0169] When the side of the segment 61 extends in the most ideal direction, the lower interior angle θ of the segment 61 refer When it is assumed that the line segment EF is approximately equal to the line segments AE and DE, the width D of the line segment 61 and the radius r of the winding turn on which the line segment 61 is located can be approximately determined using the following equation 4.

[0170] [Formula 4]

number

[0171] [Formula 5]

number

[0172] [Formula 6]

number

[0173] For example, when the electrode 60 forms a winding structure with a diameter of 22 mm and a core radius of 4 mm, the lower interior angle of the segment 61 may increase gradually or stepwise in the range of 60° to 85° in the height variable section.

[0174] As another example, the lower interior angle θ of the plurality of segment pieces 61 may increase gradually or stepwise from the core side to the outer periphery side in units of one or more groups.

[0175] On the other hand, the left lower interior angle and the right lower interior angle of the segment 61 do not have to be equal. Nevertheless, the lower interior angle θ on at least one side can be designed to satisfy the above-mentioned Equation 6.

[0176] Further referring to FIG. 4, the width d of the first portion B1 B1 The width d of the first portion B1 is designed so that when the third portion B2 is bent toward the core, the core of the electrode assembly is opened to the outside by 90% or more of its diameter. B1 may increase in proportion to the bending length of the segment 61 of group 1. The bending length corresponds to the length from the bending point to the upper edge of the segment 61. Preferably, when the electrode 60 is used to manufacture an electrode assembly for a cylindrical battery of form factor 4680, the width d of the first portion B1 B1 can be set to 180 mm to 350 mm depending on the diameter of the core of the electrode assembly and the height of the segment 61 included in group 1.

[0177] The folding points of the segments 61 may be set on a line passing through the lower end of the cutting groove 63 or at a point spaced a predetermined distance above that line. If the segments 61 are folded toward the core at a point spaced a predetermined distance from the lower end of the cutting groove 63, overlapping of the segments in the radial direction becomes easier. When the segments 61 are folded, the outer segments press against the inner segments relative to the center of the core. If the folding points are spaced a predetermined distance from the lower end of the cutting groove 63, the inner segments are pressed against the outer segments in the winding axial direction, making overlapping of the segments easier. The separation distance between the folding points is preferably 1 mm or less. Since the minimum height of the segments is 2 mm, the ratio of the separation distance between the folding points to the minimum height may be 50% or less.

[0178] In one example, the width of each segment group can be designed to form the same winding turn of the electrode assembly, where the winding turns can be counted from the end of the first portion B1 of the electrode 60 in its wound state.

[0179] In another variation, the width of each segment group can be designed to comprise at least one winding turn of the electrode assembly.

[0180] In yet another variant, the width and / or height and / or spacing pitch of the segments 61 belonging to the same segment group may increase or decrease gradually and / or stepwise and / or irregularly within a group or between adjacent groups.

[0181] Groups 1 to 8 are merely examples of the segment groups included in the third portion B2. The number of groups, the number of segment segments 61 included in each group, and the width of the group may be preferably adjusted so that the segment segments 61 are overlapped in multiple layers to maximize stress distribution during the bending process of the plain portion 43 and ensure sufficient welding strength with the current collector.

[0182] When there is one segment group, the height of the segments 61 in the third portion B2 may be uniform.

[0183] The segment structure of the third portion B2 can extend to the second portion B3 (see dotted line). In this case, the second portion B3 can also include multiple segment pieces, similar to the third portion B2. Preferably, the segment structure of the second portion B3 can be substantially identical to the outermost segment group of the third portion B2. In this case, the segment pieces included in the second portion B3 and the third portion B2 can have substantially the same width, height, and spacing pitch. Alternatively, the segment pieces of the second portion B3 can have a larger width, height, and / or spacing pitch than the third portion B2.

[0184] In the third part B2, the sections (groups 1 to 7) in which the height of the segments 61 increases stepwise based on the winding direction of the electrode 60 can be defined as segment height variable sections, and the last segment group (group 8) can be defined as a uniform height section in which the height of the segments is maintained uniform.

[0185] That is, in the third portion B2, the height of the segment 61 is changed from h1 to h N When the value increases stepwise from h1 to h N-1 The section in which the segment 61 having a height (N is a high index and is a natural number equal to or greater than 2) is arranged corresponds to the height variable section, and h NThe section where the segment 61 having a height of 10 mm or less is arranged corresponds to the uniform height section. The ratio of the variable height section and the uniform height section with respect to the length of the electrode 60 in the winding direction will be described later with reference to specific examples.

[0186] When the electrode 60 is used to manufacture an electrode assembly for a cylindrical battery of form factor 4680, the width d of the first portion B1 B1 The width of group 1 may be 35-40% of the width of first portion B1. The width of group 2 may be 130-150% of the width of group 1. The width of group 3 may be 120-135% of the width of group 2. The width of group 4 may be 85-90% of the width of group 3. The width of group 5 may be 120-130% of the width of group 4. The width of group 6 may be 100-120% of the width of group 5. The width of group 7 may be 90-120% of the width of group 6. The width of group 8 may be 115-130% of the width of group 7. The width d of second portion B3 B3 The width of the first portion B1 may be 180 to 350 mm, similar to the width of the first portion B1.

[0187] The reason why the widths of Groups 1 to 8 do not show a consistent increase or decrease pattern is that although the width of the segments gradually increases from Group 1 to Group 8, the number of segments included in a group is limited to an integer, and the thickness of the electrode varies slightly in the winding direction. Therefore, the number of segments may decrease in a particular segment group. Therefore, the width of the group may show an irregular change from the core side to the outer periphery, as shown in the example above.

[0188] That is, when the winding direction widths of 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.

[0189] In the specific example described above, groups 4 to 6 fall into this case. The width ratio of group 5 to group 4 is 120 to 130%, and the width ratio of group 6 to group 5 is 100 to 120%, which is smaller than 120 to 130%.

[0190] According to yet another variation, when the plain portion 43 of the electrode 60 has a segment structure, the electrode 60 may include a segment-omitted section 64 in which some of the multiple segments are regularly or irregularly omitted, as shown in Figure 7a.

[0191] Preferably, there may be a plurality of segment-omitted sections 64. As one example, the width of the segment-omitted sections 64 may be constant from the core side to the outer periphery side. As another example, the width of the segment-omitted sections 64 may increase or decrease regularly or irregularly from the core side to the outer periphery side. Preferably, the height of the uncoated portion present in the segment-omitted sections 64 may correspond to the height of the first portion B1 and / or the second portion B3.

[0192] The number of the segment segments 61 present between the segment-free sections 64 may be at least one. The electrode 60 may include uncoated sections in which the number of the segment segments 61 present between the segment-free sections 64 increases from the core toward the outer periphery, as shown in FIG. 7a.

[0193] Preferably, the width of the segment omission section 64 can be set so that when the electrode 60 is wound, the segment located on each winding turn is located within a predetermined independent area 66 based on the center C of the core of the electrode assembly 65, as shown in Figure 7b.

[0194] That is, when the electrode assembly 65 is viewed in the winding axis direction, the plurality of segments 61 may be located within a plurality of independent regions 66 based on the center C of the core. The number of independent regions 66 may vary, such as two, three, four, or five.

[0195] Preferably, the independent regions 66 may be fan-shaped. In this case, the angles between the independent regions 66 may be substantially uniform. Furthermore, the circumferential angle δ of the independent regions 66 may be 20° or more, optionally 25° or more, optionally 30° or more, optionally 35° or more, or optionally 40° or more.

[0196] In alternative embodiments, the independent regions 66 may have the form of a geometric figure such as a square, rectangle, parallelogram, trapezoid, or the like.

[0197] In one embodiment of the present invention, the shape of the segment 61 can be varied in various ways.

[0198] FIG. 8a is a plan view showing the structure of an electrode 70 according to another embodiment of the present invention.

[0199] Referring to FIG. 8a, the electrode 70 has substantially the same configuration as the above-described embodiment except that the shape of the segment 61' is different.

[0200] The segment 61' has a geometric shape in which the width of the upper portion and the width of the lower portion are substantially the same. Preferably, the segment 61' may be rectangular.

[0201] FIG. 8b is a diagram showing the definition of the width, height and spacing pitch of the rectangular cut pieces 61', and FIG. 8c is a partially enlarged view showing the lower part of the cutting groove 63.

[0202] 8b and 8c, the width D, height H, and spacing pitch P of the divided pieces 61' are set to sufficiently increase the number of overlapping layers of the plain portion 43 to prevent tearing of the plain portion 43 during bending and to improve the welding strength with the current collector, while also preventing abnormal deformation of the plain portion 43. Abnormal deformation refers to the plain portion below the bending point being unable to maintain a straight state and collapsing, resulting in irregular deformation.

[0203] The width D of the segment 61' is defined as the length between two points where two straight lines L2 extending from both side portions 63a of the segment 61' intersect with a straight line G extending from the lower end of the round portion 63b of the cutting groove 63 in the winding direction. The height H of the segment 61' is defined as the shortest distance between the uppermost edge of the segment 61' and the straight line G extending from the lower end of the round portion 63b of the cutting groove 63 in the winding direction. The separation pitch P of the segment 61' is defined as the length between two points where a straight line L1 connecting both ends of the round portion 63b intersects with two straight lines L2 extending from the side portions 63a of the segment 61'.

[0204] Preferably, the conditions regarding the width D, height H, and spacing pitch P of the segment 61′ are substantially the same as those in the above-described embodiment, and therefore, repeated description will be omitted. However, since the segment 61′ is rectangular, the lower interior angle of the segment 61′ may be constant at 90°.

[0205] Similar to the electrode 60, the electrode 70 may also include segment-omitted sections 64 in which some of the multiple segments are omitted regularly or irregularly, as shown in FIG. 8d.

[0206] Furthermore, when an electrode 70 including a segment-free section 64 is wound into an electrode assembly, the segments may be positioned within a plurality of independent regions 66 as shown in FIG. 7b.

[0207] When the third portion B2 and the second portion B3 include a plurality of segments 61, 61' as in the above-described embodiment, the shapes of the segments 61, 61' can be variously modified.

[0208] Preferably, the segment can be deformed in various forms while satisfying at least one of the following conditions: Condition 1: The width at the bottom is wider than the width at the top. Condition 2: The width of the bottom and the width of the top are equal. Condition 3: The width remains the same from bottom to top. Condition 4: The width decreases from bottom to top. Condition 5: The width decreases and then increases from bottom to top. Condition 6: The width increases and then decreases from bottom to top. Condition 7: The width increases from bottom to top and then remains constant. Condition 8: The width decreases from bottom to top and then remains constant. Condition 9: The interior angles on one side of the lower part are the same as the interior angles on the other side. Here, the interior angle may 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 curved, the interior angle is defined as the angle between the tangent drawn at the lowest point of the curve and the width direction of the lower part of the segment. Condition 10: The interior angles on one side of the lower part are different from the interior angles on the other side. Condition 11: The interior angle on one side of the lower part and the interior angle on the other side of the lower part are each an acute angle, a right angle, or an obtuse angle. Condition 12: Symmetrical with respect to the winding axis direction. Condition 13: Asymmetrical with respect to the winding axis direction. Condition 14: The sides are straight. Condition 15: The side is curved. Condition 16: The sides are convex outward. Condition 17: The sides are convex inward. Condition 18: The upper and / or lower corners are constructed where two straight lines intersect. Condition 19: The upper and / or lower corners are structures where straight lines and curves intersect. Condition 20: The upper and / or lower corners are structures where curves intersect with each other. Condition 21: The top and / or bottom corners are rounded.

[0209] FIG. 9 is a diagram showing an example of the shape of a segment according to a modified example of the present invention.

[0210] As shown in the drawings, the cut pieces may have various geometric shapes with the dotted line connecting the bottoms of the cut grooves on both sides as the base. The geometric shapes may have a structure in which at least one straight line, at least one curved line, or a combination thereof is connected. For example, the cut pieces may have a polygonal shape, a rounded pattern, or various shapes that combine these.

[0211] Specifically, the segment may be a symmetric trapezoid (circle a); an asymmetric trapezoid (circle b); a parallelogram (circle c); a triangle (circle l); a pentagon (circle k); an arc (circle e); or an ellipse (circle f).

[0212] The shape of the segment is not limited to that shown in FIG. 9, and may be modified to other polygonal shapes, other round shapes, or a combination thereof, so long as it satisfies at least one of the above conditions 1 to 21.

[0213] In the polygonal shapes of the segments, circle a, circle b, circle c, circle k and circle l, the upper and / or lower corners may be straight line or rounded (see enlarged upper and lower corners of circle a, see Figures 5b and 8b).

[0214] In the polygonal shapes of the segments a, b, c, k, and l, and the round shapes of the segments e and f, the interior angle θ1 on one side of the lower part and the interior angle θ2 on the other side can be the same or different, and the interior angle θ1 on one side of the lower part and the interior angle θ2 on the other side can be acute, right, or obtuse. The interior angle is the angle between the base and side of a geometric figure. When the side is curved, the straight line can be replaced by a tangent extending from the intersection of the base and side.

[0215] The shape of the sides of the polygonal segment can be varied in various ways.

[0216] As an example, the side of the segment circle a can be transformed into a curve that bulges outward, as in circle d, or into a curve that concaves inward, as in circle g or circle j.

[0217] As another example, the side of the segment with the circle a shape can be transformed into a concave folded line inward, like the shape of the circle h or circle i. Although not shown, the side of the segment with the circle a shape can be transformed into a bulging folded line outward.

[0218] In the shapes of the segments with variously modified sides, circle d, circle g, circle j, circle h, and circle i, the interior angle θ1 on one side of the lower part and the interior angle θ2 on the other side may be the same or different, and the interior angle θ1 on one side of the lower part and the interior angle θ2 on the other side may be an acute angle, a right angle, or an obtuse angle, respectively.

[0219] The width of the segment may have various change patterns from the bottom to the top.

[0220] As one example, the width of the portion may be maintained constant from bottom to top (circle c). As another example, the width of the portion may gradually decrease from bottom to top (circle a, circle b, circle d, circle e, circle f, and circle g). As yet another example, the width of the portion 61 may gradually decrease and then increase from bottom to top (circle i and circle j). As yet another example, the width of the portion may gradually increase and then decrease from bottom to top (circle k). As yet another example, the width of the portion may gradually decrease from bottom to top and then remain constant (circle h). Although not shown, the width of the portion may gradually increase from bottom to top and then remain constant.

[0221] Meanwhile, among the segment shapes exemplified in Fig. 9, polygonal shapes with flattened tops may be rotated 180°. As an example, when the segment shape circle a, circle b, circle d, or circle g is rotated 180°, the width of the segment may gradually increase from bottom to top. As another example, when the segment shape circle h is rotated 180°, the width of the segment may remain constant from bottom to top and then gradually increase.

[0222] In the above-described embodiment (variant), according to another aspect of the present invention, the shape of the segments 61, 61' may be changed along the area of ​​the third portion B2. For example, a round shape (e.g., semicircular, elliptical, etc.) that is advantageous for stress dispersion may be applied to the section where stress is concentrated, and a polygonal shape (e.g., quadrilateral, trapezoid, parallelogram, etc.) with the largest possible area may be applied to the section where stress is relatively low.

[0223] In yet another embodiment, the plurality of segments may have different shapes individually, in groups, or in groups of two or more groups along a direction parallel to the winding direction of the electrode assembly.

[0224] In the above-described embodiment (variant), the division structure of the third portion B2 may also be applied to the first portion B1. However, if the division structure is applied to the first portion B1, there is a risk of reverse forming, in which the end of the first portion B1 bends toward the outer periphery when the division pieces 61, 61' of the third portion B2 are bent due to the radius of curvature of the core. Therefore, it is preferable not to apply the division structure to the first portion B1, or, even if the division structure is applied, to adjust the width and / or height and / or spacing pitch of the division pieces 61, 61' to a small level that does not cause reverse forming, taking into account the radius of curvature of the core.

[0225] According to yet another aspect of the present invention, after the electrodes 60 and 70 are wound into an electrode assembly, the exposed portions on the upper and lower sides of the electrode assembly may overlap in multiple layers along the radial direction of the electrode assembly to form a folded surface region.

[0226] FIG. 10a is a schematic diagram showing a cross section of a folded surface region F formed by bending a segment 61 toward a core C of an electrode assembly 80. In FIG. 10a, the cross section of the folded surface region F is shown only on the left side based on the winding axis of the electrode assembly 80. The folded surface region F may be formed on both the top and bottom of the electrode assembly 80. FIG. 10b is a perspective view schematically showing an electrode assembly 80 on which a folded surface region F is formed.

[0227] 10a and 10b, the folded surface region F has a structure in which the split segments 61 are stacked in multiple layers in the winding axis direction. The stacking direction is the winding axis direction (Y axis). Section 1 is a split segment-free section (first part B1) where there are no split segments, and sections 2 and 3 are sections where winding turns including split segments are located. Section 2 is a height-variable section where the height of the split segments 61 varies, and section 3 is a height-uniform section where the split segment height is maintained uniform up to the outer periphery of the electrode assembly. As will be described later, the radial lengths of sections 2 and 3 may vary. Meanwhile, the uncoated portion (second part B3) included in at least one winding turn, including the outermost winding turn, may not include a split segment structure. In this case, section 3 may be excluded from second part B3.

[0228] In the section 2, the height of the segment 61 is the radius r1 to r N The minimum height in the section is h1 (=h min ) to maximum height h N (=h max The height variable section where the height of the segment 61 changes is r1 to r N The radius r N From the radius R of the electrode assembly 80, the height of the segment 61 is h N The uniform height means that the deviation in height is within 5%.

[0229] At any radial position in the section 2 and the section 3, the number of layers of the segment 61 varies depending on the radial position. The number of layers of the segment 61 is determined by the width of the section 2, the minimum height h1 and the maximum height h2 of the segment 61 in the height variable section. N , and may vary depending on the height change Δh of the segment 61. The number of stacked segments 61 is the number of segments that intersect with an imaginary line drawn from any radial position of the electrode assembly 80 in the direction of the winding axis.

[0230] Preferably, the number of stacked segments 61 at each position of the folded surface area F can be optimized to match the required welding strength of the current collector by adjusting the height, width and spacing pitch of the segment 61 according to the radius of the winding turn containing the segment 61.

[0231] First, when the minimum height h1 of the segment 61 is the same in the height variable section (circle 2), the maximum height h N How the number of stacked segments 61 changes along the radial direction of the folded surface region F depending on the change in the thickness of the folded surface region F will be described below with reference to a specific example.

[0232] Electrode assemblies of Examples 1-1 to 1-7 were prepared. The electrode assemblies of the Examples had a radius of 22 mm and a core diameter of 4 mm. The positive and negative electrodes included in the electrode assemblies had the electrode structure shown in FIG. 4. That is, the segment shapes were trapezoidal. The second portions B3 of the positive and negative electrodes did not include the segment. The length of the second portions B3 was 3% to 4% of the overall length of the electrode. The positive and negative electrodes and separators were wound using the method described with reference to FIG. 2. The number of winding turns ranged from 48 to 56, with the number of winding turns in the Examples being 51. The thicknesses of the positive, negative, and separator were 149 μm, 193 μm, and 13 μm, respectively. The thicknesses of the positive and negative electrodes included the thickness of the active material layer. The thicknesses of the positive and negative current collector plates were 15 μm and 10 μm, respectively. The lengths of the positive electrode and negative electrode in the winding direction are 3948 mm and 4045 mm, respectively.

[0233] In each example, the height variable section (circle 2) of the segment 61 was set to a minimum height of 3 mm so that it started from a radius of 5 mm. In addition, in each example, 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 was varied from 4 mm to 10 mm.

[0234] Specifically, in Example 1-1, the height variable section (circle 2) of the minute segment 61 is 5 mm to 6 mm, and the height of the minute segment 61 varies from a radius of 3 mm to 4 mm. In Example 1-2, the height variable section (circle 2) of the minute segment 61 is 5 mm to 7 mm, and the height of the minute segment 61 varies from 3 mm to 5 mm. In Example 1-3, the height variable section (circle 2) of the minute segment 61 is 5 mm to 8 mm, and the height of the minute segment 61 varies from 3 mm to 6 mm. In Example 1-4, the height variable section (circle 2) of the minute segment 61 is 5 mm to 9 mm, and the height of the minute segment 61 varies from 3 mm to 7 mm. In Example 1-5, the height variable section (circle 2) of the minute segment 61 is 5 mm to 10 mm, and the height of the minute segment 61 varies from 3 mm to 8 mm. In Example 1-6, the height variable section (circle 2) of the segment 61 is 5 mm to 11 mm, and the height of the segment 61 varies from 3 mm to 9 mm. In Example 1-7, the height variable section (circle 2) of the segment 61 is 5 mm to 12 mm, 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 section (circle 2) to the outer periphery. For example, in Example 1-7, the height of the segment 61 is uniform at 10 mm from a radius of 12 mm to 22 mm. In contrast, the electrode assembly of the comparative example maintains the height of the segment 61 at a uniform height of 3 mm from a radius of 5 mm to a radius of 22 mm.

[0235] FIG. 11a is a graph showing the results of counting the number of stacked segments along the radial direction in the folded surface region F of the positive electrode formed on the upper part of the electrode assembly 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 based on the center of the core, and the vertical axis of the graph represents the number of stacked segments counted at each radius point. The same applies to FIGS. 11b and 11c described below.

[0236] Referring to FIG. 11a, the uniform number of layers section b1 of the divided section appears in common in Examples 1-1 to 1-7 and Comparative Example 1. The uniform number of layers section b1 is the radius section of the flat region in each graph. The length of the uniform number of layers section b1 increases as the maximum height of the divided section decreases, and the uniform number of layers section b1' of the comparative example is the longest. On the other hand, the number of layers of the divided section increases as the maximum height h of the divided section decreases. N In other words, the maximum height of the segment h N As the width of the variable height section (circle 2) of the electrode segment increases, the number of layers in the electrode segment increases, while the width of the uniform number of layers section b1 decreases. Outside the uniform number of layers section b1, a decreasing number of layers section b2 appears, in which the number of layers in the electrode segment decreases as the radius increases. The decreasing number of layers section b2 is a radial section in which the number of layers in the electrode segment decreases as the radius of the electrode assembly increases. The uniform number of layers section b1 and the decreasing number of layers section b2 are adjacent in the radial direction and are complementary to each other. In other words, as the length of one section increases, the length of the other section decreases. Furthermore, in the decreasing number of layers section b2, the decrease in the number of layers is proportional to the distance from the uniform number of layers section b1.

[0237] In terms of the number of stacked segments, Examples 1-1 to 1-7 have 10 or more stacked segments in the uniform stacked segment number section b1. The region where the number of stacked segments is 10 or more can be set as a preferred welding target region. The welding target region is a section where at least a portion of the current collector is welded.

[0238] In Examples 1-1 to 1-7, the uniform number of layers section b1 starts at the radius point where the variable height section (circle 2) of the segment starts. That is, the variable height section (circle 2) starts at a radius of 5 mm and extends toward the outer periphery.

[0239] Table 4 below shows the results of calculating the ratio of the length of the segment-free section (c, circle 1 in Figure 10a) to the radius (ba) of the electrode assembly excluding the core for the positive electrode in Examples 1-1 to 1-7 and Comparative Example 1; the ratio (e / f) of the length of the uniform number of stacks section b1 to the length (f) from the radius point (5 mm) where the uniform number of stacks section begins to the outermost point (22 mm) of the electrode assembly; the ratio (d / f) of the length of the variable height section (d) of the segment to the length (f) from the radius point (5 mm) where the uniform number of stacks section begins to the outermost point (22 mm) of the electrode assembly; the ratio (h) of the length of the electrode region corresponding to the segment-free section (first part B1) to the entire length of the electrode; the ratio (i) of the length of the electrode region corresponding to the variable height section to the entire length of the electrode; and the ratio (i) of the electrode region corresponding to the uniform height section to the entire length of the electrode.

[0240] The negative electrode has substantially the same parameters as the positive electrode, except for a difference of 0.1 to 1.2% in parameter h. The sum of the ratios h, i, and j is slightly different from 100%. This is because there is a section without a segment in the second portion B3, which corresponds to the outer uncoated portion of the electrode. For example, in Example 1-1, there is no segment in the second portion B3, which corresponds to approximately 4% of the total length of the electrode. In Table 4, a to 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 into an electrode assembly. Furthermore, parameters corresponding to ratios (%) are rounded to the nearest tenth. These are substantially the same as in Tables 5 and 6 described below.

[0241] [Table 4]

[0242] With reference to Examples 1-1 to 1-7 in Table 4, the number of laminations of the segment segments ranged from 11 to 26, and the ratio (d / f) of the variable height section (d) to the radius section (f) containing the segment segments ranged from 6% to 41%. The ratio (e / f) of the uniform lamination number section (e) to the radius section (f) containing the segment segments ranged from 47% to 82%. The ratio (c / (ba)) of the segment-free section (c, circled 1 in Figure 10a) to the radius (ba) of the electrode assembly excluding the core was 15%. The ratio of the length of the electrode region corresponding to the segment-free section (first portion B1) to the overall length of the electrode was 6%, the ratio of the length of the electrode region corresponding to the variable height section to the overall length of the electrode was 3% to 32%, and the ratio of the length of the electrode region corresponding to the uniform height section to the overall length of the electrode was 59% to 87%. The number of laminations (g) of the uniform lamination number section was 10 or more in all of Examples 1-1 to 1-7. The uniform number of layers section (e) decreases as the height variable section (d) of the segment increases, but the number of layers (g) of the segment increases in the uniform number of layers section (e). Preferably, the uniform number of layers section (e) where the number of layers of the segment (g) is 10 or more can be set as the welding target area.

[0243] Cylindrical batteries with 1865 and 2170 form factors have an electrode assembly radius of approximately 9 mm to 10 mm. Therefore, in conventional cylindrical batteries, the radial length of the segment section (f) cannot be maintained at 17 mm, as in Examples 1-1 to 1-7, and the length of the uniform stack number section (e), where the number of segment stacks is 10 or more, cannot be maintained at 8 mm to 14 mm. This is because, in conventional cylindrical batteries, if the core radius is designed to be 2 mm, as in Examples 1-1 to 1-7, the radial section in which the segment can be arranged is essentially only 7 mm to 8 mm. Furthermore, in conventional cylindrical batteries, the length of the electrode in the winding direction is approximately 600 mm to 980 mm. This short electrode length is only approximately 15% to 24% of the length of the electrodes used in Examples 1-1 to 1-7 (positive electrode: 3948 mm, negative electrode: 4045 mm). Therefore, the numerical ranges for the parameters h, i, and j cannot be easily derived from the design specifications of conventional cylindrical batteries.

[0244] Next, in the variable height section of the section (circle 2 in Figure 10a), the maximum height of the section h N When the minimum height h1 of the segment pieces is the same, how the number of stacked segment pieces changes along the radial direction of the folded surface area F when the minimum height h1 of the segment pieces is changed will be described using a specific example.

[0245] The electrode assemblies of Examples 2-1 to 2-5 have a radius of 22 mm and a diameter of the core C of 4 mm. The minimum height h1 of the height variable section of the segment 61 (circle 2 in FIG. 10a) is 4 mm, and the maximum height h N was varied in 1 mm increments from 6 mm to 10 mm. Therefore, in the electrode assemblies of Examples 2-1 to 2-5, the widths of the section with variable segment height (circled 2 in FIG. 10a) were 2 mm, 3 mm, 4 mm, 5 mm, and 6 mm, respectively, and the section without segment (circled 1 in FIG. 10a) was a radius section with a radius of 2 mm to 6 mm.

[0246] The electrode assemblies of Examples 3-1 to 3-4 have a radius of 22 mm and a diameter of the core C of 4 mm. The minimum height h1 of the height variable section of the segment 61 (circle 2 in FIG. 10a) is 5 mm, and the maximum height h N was varied in 1 mm increments from 7 mm to 10 mm. Therefore, in the electrode assemblies of Examples 3-1 to 3-4, the widths of the section with variable segment height (circled 2 in FIG. 10a) were 2 mm, 3 mm, 4 mm, and 5 mm, respectively, and the section without segment (circled 1 in FIG. 10a) was a radius section with a radius of 2 mm to 7 mm.

[0247] The electrode assemblies of Examples 4-1 to 4-3 have a radius of 22 mm and a diameter of the core C of 4 mm. The minimum height h1 of the height variable section of the segment 61 (circle 2 in FIG. 10a) is 6 mm, and the maximum height h N was varied in 1 mm increments from 8 mm to 10 mm. Therefore, in the electrode assemblies of Examples 4-1 to 4-3, the widths of the section with variable segment height (circled 2 in FIG. 10a) were 2 mm, 3 mm, and 4 mm, respectively, and the section without segment (circled 1 in FIG. 10a) was a radius section ranging from 2 mm to 8 mm.

[0248] The electrode assemblies of Examples 5-1 and 5-2 have a radius of 22 mm and a diameter of the core C of 4 mm. The minimum height h1 of the height variable section of the segment 61 (circle 2 in FIG. 10a) is 7 mm, and the maximum height h N was varied in 1 mm increments from 9 mm to 10 mm. Therefore, in the electrode assemblies of Examples 5-1 and 5-2, the widths of the section with variable segment height (circled 2 in FIG. 10a) were 2 mm and 3 mm, respectively, and the section without segment (circled 1 in FIG. 10a) was a radius section ranging from 2 mm to 9 mm.

[0249] 11b is a graph showing the results of counting the number of stacked sections measured 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 2-1 to 2-5, 3-1 to 3-4, 4-1 to 4-3, 5-1, and 5-2. Substantially the same results are shown for the folded surface region of the negative electrode.

[0250] In Figure 11b, graph (a) shows the results of counting the number of stacked pieces along the radial direction in the folded surface region F for Examples 2-1 to 2-5, graph (b) shows the results of counting the number of stacked pieces along the radial direction in the folded surface region F for Examples 3-1 to 3-4, graph (c) shows the results of counting the number of stacked pieces along the radial direction in the folded surface region F for Examples 5-1 and 5-2.

[0251] Referring to FIG. 11b, the uniform number of layers section b1 of the sub-segment appears in all examples. The uniform number of layers section b1 is a radius section of a flat area in the graph. The length of the uniform number of layers section b1 is determined by the maximum height h1 of the sub-segment when the minimum height h1 of the sub-segment is the same. N The length of the uniform stacking section b1 is the maximum height h of the N When the number of layers is the same, the number of layers of the sub-segment increases as the minimum height h1 of the sub-segment decreases. N In the example, a section b2 with a decreased number of layers appears adjacent to a section b1 with a uniform number of layers.

[0252] In the embodiment, the number of layers of the segmented pieces in the uniform layer number section b1 is all equal to or greater than 10. Preferably, the region where the number of layers of the segmented pieces is equal to or greater than 10 can be set as a preferred welding target region.

[0253] In the examples, the uniform number of layers section b1 begins at the radial point where the variable height section of the segment (circled 2 in FIG. 10a) begins. In examples 2-1 to 2-5, the variable height section of the segment (circled 2 in FIG. 10a) begins at 6 mm and extends toward the outer periphery. In examples 3-1 to 3-4, the variable height section of the segment (circled 2 in FIG. 10a) begins at 7 mm and extends toward the outer periphery. In examples 4-3 to 4-3, the variable height section of the segment (circled 2 in FIG. 10a) begins at 8 mm and extends toward the outer periphery. In examples 5-1 and 5-2, the variable height section of the segment (circled 2 in FIG. 10a) begins at 9 mm and extends toward the outer periphery.

[0254] 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 stack count section to the length from the radius point (6 mm, 7 mm, 8 mm, 9 mm) where the uniform stack count section begins to the outermost point (22 mm) of the electrode assembly, and the ratio (d / f) of the length of the variable height section (circle 2) of the segment to the length from the radius point (6 mm, 7 mm, 8 mm, 9 mm) where the uniform stack count section begins to the outermost point (22 mm) of the electrode assembly.

[0255] [Table 5]

[0256] Referring to Examples 2-5, 3-4, 4-3, and 5-2 in Table 5 along with FIGS. 10a and 11b, the maximum height h of the segment in the height variable section (circle 2) of the segment is NAlthough the thickness is the same at 10 mm, the minimum height h1 of the segment increases by 1 mm from 4 mm, 5 mm, 6 mm, and 7 mm, and the length of the height variable section (circle 2) decreases by 1 mm from 6 mm, 5 mm, 4 mm, and 3 mm. In the four examples, the ratio (e / f) of the uniform number of layers section is the highest in Example 2-5 at 69% and the lowest in Example 5-2 at 38%, and the number of layers in the uniform number of layers section is all the same. From the results shown in Table 5, the maximum height h1 of the segment segment N When the minimum length h1 of the sub-segment is the same, the width of the uniform number of layers section increases proportionally as the minimum height h1 of the sub-segment decreases and the width of the variable height section (circle 2) of the sub-segment increases. This is because the smaller the minimum length h1 of the sub-segment, the closer the radius point where the sub-segment starts to the core side, and the area where the sub-segments are stacked expands toward the core side.

[0257] Referring to Table 5, the number of layers of the segment is 16 to 26, the ratio (d / f) of the segment height variable section (circle 2) is 13% to 38%, and the ratio (e / f) of the uniform layer number section is 31% to 69%. The ratio (c / (ba)) of the segment-free section (circle 1) to the radius (ba) of the electrode assembly excluding the core is 20% to 35%. The ratio of the length of the electrode region corresponding to the segment-free section (circle 1) to the overall 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 overall length of the electrode is 6% to 25%, and the ratio of the length of the electrode region corresponding to the uniform height section (circle 3) to the overall length of the electrode is 62% to 81%.

[0258] Cylindrical batteries with 1865 and 2170 form factors have electrode assembly radii of approximately 9 mm to 10 mm. Therefore, unlike the examples, the radial length of the segment section (f) cannot be secured at 13 mm to 16 mm. The length of the segment-free section (c, circle 1) cannot be secured at 4 mm to 7 mm, while the length of the uniform-number section (e) with 10 or more segment stacks cannot be secured at 5 mm to 11 mm. This is because, in conventional cylindrical batteries, if the core radius is designed to be 2 mm as in the examples, the radius section in which segment sections can be arranged is essentially only 7 mm to 8 mm. Furthermore, in conventional cylindrical batteries, the winding length of the electrodes is approximately 600 mm to 980 mm. These short electrode lengths are only approximately 15% to 24% of the electrode lengths in the examples (3948 mm for positive electrode and 4045 mm for negative electrode). Therefore, the numerical ranges for the parameters h, i, and j cannot be easily derived from the design specifications of conventional cylindrical batteries.

[0259] Next, in the variable height section (circle 2), the minimum height h1 and maximum height h N When the diameter of the core C of the electrode assembly is the same, how the number of laminations of the segmented pieces changes along the radial direction of the folded surface area F will be explained using a specific example.

[0260] 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 61 in the height variable section (circle 2) is 3 mm, and the maximum height h N was varied in 1 mm increments from 5 mm to 10 mm. Therefore, in the electrode assemblies of Examples 6-1 to 6-6, the widths of the section (circle 2) where the height of the segment was variable were 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, and 7 mm, respectively, and the section (circle 1) where the segment was omitted was a radius section ranging from 4 mm to 7 mm.

[0261] The electrode assemblies of Examples 7-1 to 7-6 have a radius of 22 mm, and the radius of the core C is 2 mm. The minimum height h1 of the segment 61 in the height variable section (circle 2) is 3 mm, and the maximum height hN was varied in 1 mm increments from 5 mm to 10 mm. Therefore, in the electrode assemblies of Examples 7-1 to 7-6, the widths of the section (circle 2) where the height of the segment was variable were 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, and 7 mm, respectively, and the section (circle 1) where no segment was present was all the same as the radius section from 2 mm to 5 mm.

[0262] 11c is a graph showing the results of counting the number of stacked sections measured 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 6-1 to 6-6 and 7-1 to 7-6. Substantially the same results are observed in the folded surface region of the negative electrode.

[0263] In FIG. 11c, graph (a) shows the results of counting the number of stacked sections measured along the radial direction in the folded surface region F for Examples 6-1 to 6-6, and graph (b) shows the results of counting the number of stacked sections measured along the radial direction in the folded surface region F for Examples 7-1 to 7-6.

[0264] Referring to FIG. 11c, the uniform number of layers section b1 of the segment appears in all examples. The uniform number of layers section b1 is a radial section of a flat area in the graph. The radial length of the uniform number of layers section b1 is the same as the maximum height h1 of the segment when the minimum height h1 of the segment is the same. N On the other hand, in the uniform stacking section b1, the number of stacks of the sub-section increases as the maximum height h N In the example, a section b2 with a reduced number of layers is observed adjacent to the section b1 with a uniform number of layers.

[0265] In the embodiment, the number of layers of the segmented pieces in the uniform layer number section b1 is all equal to or greater than 10. Preferably, the region where the number of layers of the segmented pieces is equal to or greater than 10 can be set as a preferred welding target region.

[0266] In the examples, the uniform number of layers section b1 starts at the radius where the variable height section (circle 2) of the segment starts. In Examples 6-1 to 6-6, the radius where the variable height section (circle 2) of the segment starts is 7 mm, and in Examples 7-1 to 7-6, the radius where the variable height section (circle 2) of the segment starts is 5 mm.

[0267] Table 6 below shows the calculation results of 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 stack count section to the length from the radius point (7 mm, 5 mm) where the uniform stack count section begins to the outermost point (22 mm) of the electrode assembly, and the ratio (d / f) of the length of the variable height section (circle 2) of the segment to the length from the radius point (7 mm, 5 mm) where the uniform stack count section begins to the outermost point (22 mm) of the electrode assembly.

[0268] [Table 6]

[0269] Referring to FIG. 10a and Examples 6-6 and 7-6 in Table 6, the minimum height h1 and maximum height h2 of the segment in the variable height section (circle 2) of the segment are Nare the same, at 3 mm and 10 mm, respectively. However, Example 6-6 has a core radius that is 2 mm larger than Example 7-6. Therefore, Example 6-6 has a uniform lamination count section (e) and a segment section (f) that are 2 mm smaller than Example 7-6, but the number of laminations in the segment in the uniform lamination 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 variable height section (circle 2) of the segment is the same, as the core radius (a) becomes smaller, the ratio (d / f) of the variable height section (circle 2) decreases while the ratio (e / f) of the uniform lamination count section increases. Referring to Table 6, it can be seen that the number of laminations in the segment ranges from 13 to 26, the ratio (d / f) of the variable height section (circle 2) of the segment ranges from 12% to 47%, and the ratio (e / f) of the length of the uniform lamination count section ranges from 40% to 76%. The ratio (c / (ba)) of the segment-free section (circle 1) to the radius (ba) of the electrode assembly excluding the core is 15% to 17%. The ratio of the length of the electrode region corresponding to the segment-free section (circle 1) to the overall 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 overall 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 overall length of the electrode is 59% to 83%.

[0270] Cylindrical batteries with 1865 and 2170 form factors have an electrode assembly radius of approximately 9 mm to 10 mm. Therefore, unlike the examples, the radial length of the segment section (f) cannot be secured at 15 mm to 17 mm. It is also impossible to secure a length of approximately 3 mm for the segment-free section (circled 1) while simultaneously securing a length of 6 mm to 13 mm for the uniform-number section (e) with 10 or more segment stacks. This is because, in conventional cylindrical batteries, if the core radius is designed to be 2 mm to 4 mm, as in the examples, the radius section in which segment sections can be arranged is essentially only 5 mm to 8 mm. Furthermore, in conventional cylindrical batteries, the electrode winding length is approximately 600 mm to 980 mm. Such short electrode lengths are only approximately 15% to 24% of the electrode lengths in the examples (3948 mm for the positive electrode and 4045 mm for the negative electrode). Therefore, the numerical ranges for the parameters h, i, and j cannot be easily derived from the design specifications of conventional cylindrical batteries.

[0271] Considering the data in Tables 4 to 6 comprehensively, the number of layered segments in the uniform layered segment section may be 11 to 26. The ratio (d / f) of the variable layered segment section (circled 2) may be 6% to 47%. The ratio (e / f) of the uniform layered segment section may be 31% to 82%. The ratio (c / (ba)) of the length of the layered segment-free section (circled 1) to the radius of the electrode assembly excluding the core may be 15% to 35%. The ratio of the length of the electrode region corresponding to the layered segment-free section (circled 1) to the overall length of the electrode (length in the winding direction) may be 6% to 20%. The ratio of the length of the electrode region corresponding to the variable layered segment section (circled 2) to the overall length of the electrode may be 3% to 32%. The ratio of the length of the electrode region corresponding to the uniform layered segment section (circled 3) to the overall length of the electrode may be 59% to 87%.

[0272] Meanwhile, the parameters explained in Tables 4 to 6 are the radius of the core (a); the radius of the electrode assembly (b); the minimum height h1 and the maximum height h2 in the height variable section (circle 2) of the section. NThe change in height of the segment per 1 mm increase in radius, Δh, can vary depending on design factors including the thickness of the positive electrode, negative electrode, and separator.

[0273] Therefore, the number of layered segments in the uniform layered segment section can be expanded to 10 to 35. The ratio (d / f) of the variable layered segment section (circle 2) can be expanded to 1% to 50%. The ratio (e / f) of the uniform layered segment section can be expanded to 30% to 85%. The ratio (c / (ba)) of the length of the layered segment-free section (circle 1) to the radius of the electrode assembly excluding the core can be expanded to 10% to 40%. The ratio of the length of the electrode region corresponding to the layered segment-free section (circle 1) to the overall length of the electrode (length in the winding direction) can be expanded to 1% to 30%. The ratio of the length of the electrode region corresponding to the variable layered segment section (circle 2) to the overall length of the electrode can be expanded to 1% to 40%. The ratio of the length of the electrode region corresponding to the uniform layered segment section (circle 3) to the overall length of the electrode can be expanded to 50% to 90%. In the above-mentioned 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 height change amount Δh of the segment in the radial direction of the electrode assembly. When the radial length of the height variable section (circle 2) is fixed, as the height change amount Δh of the segment decreases, the height index N increases, and vice versa is also possible. Preferably, the height index N is 2 to 20, and optionally can be further extended to 2 to 30.

[0274] In the folded surface regions F formed on the upper and lower parts of the electrode assembly, the lamination number uniform sections can be used as welding target regions of the current collector.

[0275] Preferably, the welding region of the current collector overlaps the uniform lamination number section by at least 50% in the radial direction of the electrode assembly, and the higher the overlap ratio, the more preferable.

[0276] Preferably, the other region of the welding region of the current collector that does not overlap with the uniform lamination number section can overlap with the decreasing lamination number section adjacent to the uniform lamination number section in the radial direction.

[0277] More preferably, other regions of the welding region of the current collector that do not overlap with the uniform lamination number section can overlap with regions of the reduced lamination number section where the overlapping number of the divided segments is 10 or more.

[0278] Welding the current collector to the region where the number of laminated segments is 10 or more is preferable in terms of welding strength and preventing damage to the separator and active material layer during welding, and is particularly useful when welding the current collector using a high-power laser with high transmission characteristics.

[0279] When a uniform stacking section, in which 10 or more divided pieces are stacked, is welded to a current collector using a laser, even if the laser output is increased to improve welding quality, the uniform stacking section absorbs most of the laser energy to form a weld bead, preventing the separator and active material layer below the folded surface region F from being damaged by the laser.

[0280] In addition, the area irradiated with the laser has 10 or more stacked pieces, so the weld beads are formed with sufficient volume and thickness, ensuring sufficient weld strength and reducing the resistance of the weld interface to a level suitable for fast charging.

[0281] The laser power used to weld the current collector can be determined by the desired weld strength between the folded surface region F and the current collector. The weld strength increases in proportion to the number of stacked segments. This is because the greater the number of stacked segments, the larger the volume of the weld bead formed by the laser. The weld bead is formed as the current collector material and the segment material are melted together. Therefore, a larger volume of the weld bead provides a stronger bond between the current collector and the folded surface region, lowering the contact resistance at the weld interface.

[0282] Preferably, the welding strength is 2 kgf / cm 2 More than 4kgf / cm 2 The maximum welding strength may vary depending on the output of the laser welding device. As an example, the welding strength is preferably 8 kgf / cm 2 Less than 6kgf / cm, more preferably 2 The following may be set: However, the present invention is not limited to this.

[0283] When the weld strength satisfies the above numerical range, the physical properties of the weld interface do not deteriorate even when the electrode assembly is subjected to severe vibrations in the winding axial direction and / or radial direction, and the resistance of the weld interface can also be reduced due to the sufficient volume of the weld beads.

[0284] The laser output required to meet the welding strength requirements varies depending on the laser device, but can be appropriately adjusted within the range of 250W to 320W or within the range of 40% to 100% of the maximum laser output specification provided by the device.

[0285] The weld strength is the tensile force per unit area of ​​the current collector (kgf / cm) when the current collector begins to separate from the folded surface area F. 2 ) can be defined as the weld strength. Specifically, after welding of the current collector is completed, a tensile force is applied to the current collector and the magnitude of the force is gradually increased. When the tensile force exceeds a critical value, the pieces begin to separate from the weld interface. At this time, the tensile force applied to the current collector divided by the area of ​​the current collector corresponds to the weld strength.

[0286] The folded surface region F is formed by stacking a plurality of layers of segment pieces, and according to the above-described embodiment, the number of stacked segment pieces can be increased from a minimum of 10 to a maximum of 35.

[0287] The thickness of the positive electrode current collector (foil) constituting the uncoated portion 43 may be 10 μm to 25 μm, and the thickness of the negative electrode current collector (foil) constituting the uncoated 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 laminated thickness of the divided pieces is 100 μm to 875 μm. Also, the folded surface region F of the negative electrode may include a region where the total laminated thickness of the divided pieces is 50 μm to 700 μm.

[0288] FIG. 12 is a top view of an electrode assembly showing a uniform lamination number section b1 and a reduced lamination number section b2 in the folded surface region F of the divided segments 61 and 61' according to an embodiment of the present invention.

[0289] Referring to Figure 12, the area between the two circles indicated by the thick solid lines corresponds to the folded surface area F of the segment, the area between the two circles indicated by the dashed dotted lines corresponds to the uniform layer count section b1 where the number of layers of the segment is 10 or more, and the area outside the uniform layer count section b1 corresponds to the reduced layer count section b2.

[0290] As an example, the current collector P c is welded to the folded surface area F, the current collector P c Welding pattern W on the surface p is generated. Welding pattern W p can be an array of line patterns or dot patterns. p corresponds to the welding area and can overlap with the uniform number of layers section b1 of the divided section along the radial direction by 50% or more. Therefore, the welding pattern W p A part of the layer count uniformity section b1 is included, and the remaining welding pattern W p The welding pattern W can be included in the layer number decreasing section b2 outside the layer number uniform section b1. Of course, in order to maximize the welding strength and reduce the resistance of the welding area, p The entirety can overlap with the uniform stack number section b1.

[0291] The area of ​​the folded surface region F can be defined as the sum of the area of ​​the uniform lamination number section b1 and the area of ​​the reduced lamination number section b2 of the divided piece. The ratio (e / f) of the uniform lamination number section b1 is 30% to 85%, preferably 31% to 82%, so the ratio of the area of ​​the uniform lamination 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 ) can be.

[0292] Preferably, the current collector P c The ends of the portions that contact the folded surface region F may cover the ends of the partial segments 61, 61' that are folded toward the core C in the final winding turn of the uniform height section (circle 3). In this case, the partial segments 61, 61' are folded toward the current collector P. c The welding pattern W is pressed by p is formed, the current collector P c and the folded surface region F are strongly bonded. As a result, the divided pieces 61, 61' stacked in the winding axis direction are tightly adhered to each other, which reduces the resistance at the welding interface and prevents the divided pieces 61, 61' from lifting up.

[0293] Meanwhile, the bending direction of the split pieces may be opposite to the above-described direction. That is, the split pieces may be bent from the core side toward the outer periphery. In this case, the pattern in which the height of the split pieces changes along the winding direction (X-axis direction) may be opposite to that of the above-described embodiment (variant). For example, the height of the split pieces may decrease stepwise from the core side toward the outer periphery. Furthermore, the structure applied to the first part B1 and the structure applied to the second part B3 may be interchangeable. Preferably, the height of the split pieces may decrease stepwise from the core side toward the outer periphery, and the split piece height change pattern may be designed so that when the split piece closest to the outer periphery of the electrode assembly is bent toward the outer periphery, the end of the split piece does not protrude outside the outer periphery of the electrode assembly.

[0294] The electrode structure of the above-described embodiment (variant) may be applied to at least one of the first and second electrodes of 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 (variant) is applied to one of the first and second electrodes, a conventional electrode structure may be applied to the other. Furthermore, the electrode structures applied to the first and second electrodes may not be the same, but may be different.

[0295] As an example, when the first electrode and the second negative electrode are a positive electrode and a negative electrode, respectively, any one of the embodiments (variants) may be applied to the first electrode, and a conventional electrode structure (see FIG. 1) may be applied to the second electrode.

[0296] As another example, when the first electrode and the second electrode are a positive electrode and a negative electrode, respectively, any one of the embodiments (variants) may be selectively applied to the first electrode, and any one of the embodiments (variants) may be selectively applied to the second electrode.

[0297] 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 may be any active material known in the art without limitation.

[0298] As an example, the positive electrode active material has the general chemical formula A[A x M y ]O 2+z (A includes at least one element of Li, Na, and K; M includes at least one element selected from Ni, Co, Mn, Ca, Mg, Al, Ti, Si, Fe, Mo, V, Zr, Zn, Cu, Al, Mo, Sc, Zr, Ru, and Cr; x≧0, 1≦x+y≦2, −0.1≦z≦2; and the stoichiometric coefficients x, y, and z are selected to maintain electroneutrality of the compound).

[0299] As another example, the positive electrode active material may be an alkali metal compound xLiM disclosed in U.S. Pat. No. 6,677,082, U.S. Pat. No. 6,680,143, etc. 1 O2-(1-x)Li2M2 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) can be.

[0300] As another example, the positive electrode active material has the general 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 lithium metal phosphate represented by Li3M2(PO4)3 [M contains at least one element selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Al, Mg and Al] can be.

[0301] Preferably, the positive electrode active material may contain primary particles and / or secondary particles aggregated from primary particles.

[0302] 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, low-crystalline carbon, high-crystalline carbon, etc. can all be used.

[0303] The separator may be a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, an ethylene / methacrylate copolymer, etc., either alone or in a laminate. Alternatively, the separator may be a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc.

[0304] At least one surface of the separator may include a coating layer of inorganic particles. Alternatively, the separator itself may be made of a coating layer of inorganic particles. The particles constituting the coating layer may have a structure in which they are bound with a binder so that there is interstitial volume between adjacent particles.

[0305] The inorganic particles may be made of an inorganic material having a dielectric constant of 5 or more. Non-limiting examples of the inorganic particles include Pb(Zr,Ti)O3 (PZT), Pb 1-x La x ZR 1-y Ti y O3(PLZT), PB(Mg3Nb 2 / 3 )O3-PbTiO3 (PMN-PT), BaTiO3, hafnia (HfO2), SrTiO3, TiO2, Al2O3, ZrO2, SnO2, CeO2, MgO, CaO, ZnO, and Y2O3.

[0306] Hereinafter, the structure of an electrode assembly according to an embodiment of the present invention will be described in detail.

[0307] FIG. 13 is a cross-sectional view of a jelly roll type electrode assembly 100 in which the electrode 60 of the embodiment is applied to the first electrode (positive electrode) and the second electrode (negative electrode), taken along the Y-axis direction (winding axis direction).

[0308] Referring to FIG. 13, the uncoated 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.

[0309] The height of the uncoated portion of the first portion B1 is relatively smaller than the height of the division segment 61. In addition, in the third portion B2, the folding length of the innermost division segment 61 is equal to or shorter than the radial length R of the first portion B1. The folding length H corresponds to the distance from the point where the innermost division segment 61 is folded to the upper end of the division segment 61. In a modified example, the folding length H may be smaller than the sum of the radial length R of the winding turn formed by the first portion B1 and 10% of the radius of the core 102.

[0310] Therefore, even if the divided piece 61 is bent, 90% or more of the diameter of the core 102 of the electrode assembly 100 is open to the outside. The core 102 is a cavity in the center of the electrode assembly 100. If the core 102 is not blocked, the electrolyte injection process can be carried out without any problems, improving the efficiency of the electrolyte injection. In addition, a welding jig can be inserted through the core 102 to easily perform the welding process between the negative (or positive) electrode side current collector plate and the battery housing (or rivet terminal).

[0311] The height of the uncoated portion of the second part B3 is relatively lower than the height of the dividing piece 61. Therefore, when the beading portion of the battery housing is pressed near the wound turn of the second part B3, it is possible to prevent the beading portion from coming into contact with the upper periphery of the electrode assembly 100, which could cause an internal short circuit.

[0312] In one variation, the second portion B3 may include a segment 61, and the height of the segment 61 of the second portion B3 may decrease gradually or in steps, unlike the illustration in Fig. 13. Also, in Fig. 13, the height of the segment 61 is uniform in a portion on the outer periphery, but the height of the segment 61 may increase gradually or in steps from the boundary between the first portion B1 and the third portion B2 to the boundary between the third portion B2 and the second portion B3. The section where the height of the segment 61 changes corresponds to the segment height variable section (circled 2 in Fig. 10a).

[0313] The second uncoated portion 43b has the same structure as the first uncoated portion 43a. In one variation, the second uncoated portion 43b may have a conventional electrode structure or an electrode structure of another embodiment (variation).

[0314] The end 101 of the segment 61 may be bent in the radial direction of the electrode assembly 100, for example, from the outer periphery toward the core. At this time, the uncoated portions of the first portion B1 and the second portion B3 are not substantially bent.

[0315] The third portion B2 includes a plurality of radially arranged division segments 61, which reduces bending stress and prevents tearing or abnormal deformation of the uncoated portions 43a, 43b near the bending points. In addition, when the width, height, and / or spacing pitch of the division segments 61 are adjusted within the ranges of the above-described embodiments, the division segments 61 are overlapped to an extent that sufficient welding strength can be ensured while being bent toward the core, and no open spaces (gaps) are formed in the bending surface region F.

[0316] FIG. 14 is a cross-sectional view of an electrode assembly 110 according to yet another embodiment of the present invention, taken along the Y-axis direction (winding axis direction).

[0317] Referring to Figure 14, the electrode assembly 110 is substantially identical in configuration to the electrode assembly 100 of Figure 13, except that the second part B3 also includes a segment 61, and the height of the segment 61 of the second part B3 is substantially the same as the height of the outermost segment 61 of the third part B2.

[0318] In the electrode assembly 110, the height of the uncoated portion of the first portion B1 is relatively lower than the height of the segment 61 included in the third portion B2. Furthermore, the bent length H of the innermost segment 61 in the third portion B2 is equal to or shorter than the radial length R of the winding turn formed by the first portion B1. Preferably, the winding turn formed by the first portion B1 may be a segment-omitted section (circled 1 in FIG. 10a) without a segment. In a variant, the bent length H may be smaller than the sum of the radial length R of the winding turn formed by the first portion B1 and 10% of the radius of the core 112.

[0319] Therefore, even if the divided piece 61 included in the third part B2 is bent, 90% or more of the diameter of the core 112 of the electrode assembly 110 is open to the outside. If the core 112 is not blocked, the electrolyte injection process can be performed without any problems, improving the efficiency of the electrolyte injection. In addition, a welding jig can be inserted through the core 112 to easily perform the welding process between the negative (or positive) side current collector plate and the battery housing (or rivet terminal).

[0320] In one variation, the structure in which the height of the segment 61 included in the third portion B2 increases gradually or in steps from the core side toward the outer periphery may be extended to the winding turn formed by the second portion B3. In this case, the height of the segment 61 may increase gradually or in steps from the boundary between the first portion B1 and the third portion B2 to the outermost surface of the electrode assembly 110.

[0321] The second uncoated portion 43b has the same structure as the first uncoated portion 43a. In one variation, the second uncoated portion 43b may have a conventional electrode structure or an electrode structure of another embodiment (variation).

[0322] The end 111 of the segment 61 included in the third portion B2 may be bent in the radial direction of the electrode assembly 110, for example, from the outer periphery toward the core. At this time, the uncoated portion of the first portion B1 is not substantially bent.

[0323] The third portion B2 includes a plurality of radially arranged division segments 61, which reduces bending stress and prevents tearing or abnormal deformation of the uncoated portions 43a, 43b near the bending points. In addition, when the width and / or height and / or spacing pitch of the division segments 61 are adjusted within the ranges of the above-described embodiments, the division segments 61 are overlapped to an extent that sufficient welding strength can be ensured while being bent toward the core, and no open spaces (gaps) are formed in the bent surface area.

[0324] FIG. 15 is a cross-sectional view of an electrode assembly 120 according to yet another embodiment of the present invention, taken along the Y-axis direction (winding axis direction).

[0325] 15, the electrode assembly 120 is substantially identical in configuration to the electrode assembly 100 of FIG. 13, except that the height of the segment 61 included in the third portion B2 gradually or stepwise increases and then decreases. The radial section where the height of the segment 61 varies may be considered a variable-height section of the segment (circled 2 in FIG. 10a). In this case, too, the variable-height section of the segment 61 may be designed so that a uniform stack number section, where the number of stacked segments of the segment 61 is 10 or more, appears in the bending surface region F formed as the segment 61 is bent, within the above-mentioned preferred numerical range.

[0326] In the electrode assembly 120, the height of the uncoated portion of the first portion B1 is relatively shorter than the height of the segment 61. The bent length H of the segment 61 closest to the core 122 is equal to or shorter than the radial length R of the winding turn formed by the first portion B1. The section corresponding to the winding turn formed by the first portion B1 corresponds to the segment-omitted section (circled 1 in FIG. 10a) where no segment is present. In a modified example, the bent length H may be smaller than the sum of the radial length R of the winding turn formed by the first portion B1 and 10% of the radius of the core 102.

[0327] Therefore, even if the divided piece 61 included in the third part B2 is bent toward the core side, 90% or more of the diameter of the core 122 of the electrode assembly 120 is open to the outside. If the core 122 is not blocked, the electrolyte injection process can be performed without any problems, improving the efficiency of the electrolyte injection. In addition, a welding jig can be inserted through the core 122 to easily perform the welding process between the negative (or positive) side current collector plate and the battery housing (or rivet terminal).

[0328] In addition, the height of the uncoated portion of the second part B3 is relatively lower than the height of the dividing segment 61, and preferably, the dividing segment 61 may not be formed on the second part B3. Therefore, when the beading portion of the battery housing is pressed near the wound turn formed by the second part B3, it is possible to prevent the beading portion and the periphery of the electrode assembly 120 from coming into contact with each other and causing an internal short circuit. In one variation, the second part B3 may include a dividing segment, and the height of the dividing segment of the second part B3 may decrease gradually or in steps toward the outer periphery.

[0329] The second uncoated portion 43b has the same structure as the first uncoated portion 43a. In a modified example, the second uncoated portion 43b may have a conventional electrode structure or an electrode structure of another embodiment (modified example).

[0330] The end 121 of the segment 61 included in the third portion B2 may be bent from the outer periphery of the electrode assembly 120 toward the core. At this time, the uncoated portions of the first portion B1 and the second portion B3 are not substantially bent.

[0331] The third portion B2 includes a plurality of radially arranged divisional segments 61, which reduces bending stress and prevents tearing or abnormal deformation of the uncoated portions 43a, 43b. In addition, when the width, height, and / or spacing of the divisional segments 61 are adjusted within the ranges of the above-described embodiments, the divisional segments 61 are overlapped to an extent that sufficient welding strength can be ensured while being bent toward the core, and no open spaces (gaps) are formed in the bent surface region F.

[0332] FIG. 16 is a cross-sectional view of an electrode assembly 130 according to yet another embodiment of the present invention, taken along the Y-axis direction (winding axis direction).

[0333] Referring to FIG. 16, the electrode assembly 130 is substantially identical in configuration to the electrode assembly 120 of FIG. 15, except that the second portion B3 includes a segment 61, and the height of the segment 61 has a pattern in which it gradually or stepwise decreases from the boundary between the second portion B3 and the third portion B2 toward the outermost surface of the electrode assembly 130.

[0334] In the electrode assembly 130, the height of the uncoated portion of the first portion B1 is relatively shorter than the height of the segment 61. The bent length H of the segment 61 closest to the core 132 is equal to or shorter than the radial length R of the winding turn formed by the first portion B1. The winding turn formed by the first portion B1 corresponds to the segment-omitted section (circled 1 in FIG. 10a) where no segment is present. In a variant, the bent length H may be smaller than the sum of the radial length R of the winding turn formed by the first portion B1 and 10% of the radius of the core 102.

[0335] Therefore, even if the divided piece 61 included in the third part B2 is bent toward the core side, 90% or more of the diameter of the core 132 of the electrode assembly 130 is open to the outside. If the core 132 is not blocked, the electrolyte injection process can be performed without any problems, improving the efficiency of the electrolyte injection. In addition, a welding jig can be inserted through the core 132 to easily perform the welding process between the negative (or positive) electrode side current collector plate and the battery housing (or rivet terminal).

[0336] The second uncoated portion 43b has the same structure as the first uncoated portion 43a. In one variation, the second uncoated portion 43b may have a conventional electrode structure or an electrode structure of another embodiment (variation).

[0337] The end 131 of the segment 61 included in the third portion B2 may be bent from the outer periphery of the electrode assembly 130 toward the core. At this time, the uncoated portion of the first portion B1 is not substantially bent.

[0338] The third portion B2 includes a plurality of radially arranged division segments 61, which reduces bending stress and prevents tearing or abnormal deformation of the uncoated portions 43a, 43b near the bending points. In addition, when the width, height, and / or spacing pitch of the division segments 61 are adjusted within the ranges of the above-described embodiments, the division segments 61 are overlapped to an extent that sufficient welding strength can be ensured while being bent toward the core, and no open spaces (gaps) are formed in the bending surface region F.

[0339] Meanwhile, in the above-described embodiment (variant), the end of the portion 61 included in the third portion B2 may be bent from the core side toward the outer periphery. In this case, it is preferable that the winding turn formed by the second portion B3 be designed as a portion-omitted section (circled 1 in FIG. 10a) without a portion, and not be bent toward the outer periphery. Furthermore, the radial width of the winding turn formed by the second portion B3 may be equal to or greater than the length of the bent portion of the outermost portion. Therefore, when the outermost portion is bent toward the outer periphery, the end of the bent portion does not protrude beyond the outer periphery of the electrode assembly toward the inner surface of the battery housing. Furthermore, the structural change pattern of the portion 61 included in the third portion B2 may be opposite to that of the above-described embodiment (variant). For example, the height of the portion 61 may increase stepwise or gradually from the core side toward the outer periphery. That is, by sequentially arranging a section where segment pieces are omitted (circle 1 in Figure 10a), a section where segment piece heights are variable (circle 2 in Figure 10a), and a section where segment piece heights are uniform (circle 3 in Figure 10) from the outer periphery side to the core side of the electrode assembly, it is possible to make a uniform stack number section where the number of segment piece stacks is 10 or more appear in a preferred numerical range in the folded surface region F.

[0340] Various electrode assembly structures according to embodiments of the present invention can be applied to jelly-roll type cylindrical batteries.

[0341] Preferably, the cylindrical battery may have a form factor ratio (defined as the diameter divided by the height of a cylindrical battery, i.e., the ratio of height (H) to diameter (Φ)) of greater than about 0.4, where form factor refers to the diameter and height of a cylindrical battery.

[0342] Preferably, the diameter of the cylindrical battery may be 35 mm or more, preferably 40 mm to 50 mm. The height of the cylindrical battery may be 70 mm or more, preferably 75 mm to 90 mm. In one embodiment, the cylindrical battery may be, for example, a 46110 battery, a 4875 battery, a 48110 battery, a 4880 battery, or a 4680 battery. In the number indicating the form factor, the first two digits indicate the diameter of the battery, and the remaining digits indicate the height of the battery.

[0343] When an electrode assembly having a tabless structure is applied to a cylindrical battery with a form factor ratio exceeding 0.4, the uncoated portion is easily torn due to the large radial stress applied when the uncoated portion is bent. Furthermore, when welding a current collector plate to the bent surface area of ​​the uncoated portion, the number of layers of the uncoated portion in the bent surface area must be increased to ensure sufficient welding strength and reduce resistance. These requirements can be met by the electrode and electrode assembly according to an embodiment (variant) of the present invention.

[0344] A battery according to one embodiment of the present invention may be a generally cylindrical battery having a diameter of about 46 mm, a height of about 110 mm, and a form factor ratio of 0.418.

[0345] Another embodiment of the battery may be a generally cylindrical battery having a diameter of about 48 mm, a height of about 75 mm, and a form factor ratio of 0.640.

[0346] In yet another embodiment, the battery may be a generally cylindrical battery having a diameter of about 48 mm, a height of about 110 mm, and a form factor ratio of 0.436.

[0347] In yet another embodiment, the battery may be a generally cylindrical battery having a diameter of about 48 mm, a height of about 80 mm, and a form factor ratio of 0.600.

[0348] In yet another embodiment, the battery may be a generally cylindrical battery having a diameter of about 46 mm, a height of about 80 mm, and a form factor ratio of 0.575.

[0349] Conventionally, batteries with a form factor ratio of approximately 0.4 or less have been used. For example, 1865 batteries and 2170 batteries have been used. The 1865 battery has a diameter of approximately 18 mm, a height of approximately 65 mm, and a form factor ratio of 0.277. The 2170 battery has a diameter of approximately 21 mm, a height of approximately 70 mm, and a form factor ratio of 0.300.

[0350] Hereinafter, a cylindrical battery according to an embodiment of the present invention will be described in detail.

[0351] FIG. 17 is a cross-sectional view of a cylindrical battery 190 according to an embodiment of the present invention taken along the Y-axis direction.

[0352] Referring to FIG. 17, a cylindrical battery 190 according to one embodiment of the present invention includes an electrode assembly 110 including a first electrode, a separator, and a second electrode, a battery housing 142 that houses the electrode assembly 110, and a seal 143 that seals the open end of the battery housing 142.

[0353] The battery housing 142 is a cylindrical container with an opening at the top. The battery housing 142 is made of a conductive metal material such as aluminum, steel, or stainless steel. A nickel coating layer may be formed on the surface of the battery housing 142. The battery housing 142 accommodates the electrode assembly 110 in the internal space through the opening at the top, along with the electrolyte.

[0354] The electrolyte is A + B - where A + Li + , Na + , K. + or a combination thereof. - is F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , AlO4 - , AlCl4 - , PF6 - , SbF6 - , AsF6 - , BF2C2O4 - , BC4O8 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , CF3SO3 - , C4F9SO3 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2- , CH3CO2 - , SCN - and (CF3CF2SO2)2N - The anion comprises one or more anions selected from the group consisting of:

[0355] The electrolyte may be dissolved in an organic solvent such as propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), γ-butyrolactone, or a mixture thereof.

[0356] The electrode assembly 110 may have a jelly-roll structure. As shown in FIG. 2, the electrode assembly 110 may be manufactured by stacking a lower separator, a first electrode, an upper separator, and a second electrode in order at least once, and winding the stack around a winding center C.

[0357] The first electrode and the second electrode have opposite polarities. That is, one has a positive polarity and the other has a negative polarity. At least one of the first electrode and the second electrode may have an electrode structure according to the above-described embodiment (variant). The other of the first electrode and the second electrode may have a conventional electrode structure or an electrode structure according to the embodiment (variant). The number of electrode pairs included in the electrode assembly 110 is not limited to one, but may be two or more.

[0358] The pieces included in the third portion B2 are bent in the radial direction of the electrode assembly 110, for example, from the outer periphery toward the core, thereby forming a bent surface region F.

[0359] The first portion B1 is shorter than the other portions and corresponds to the segment omitting section a1 having no segment, and therefore is not bent toward the core side.

[0360] Preferably, the folded surface region F may include, in order from the core side to the outer periphery side, a segment-omitted section a1, a segment-height variable section a2, and a segment-height uniform section a3.

[0361] As shown in FIGS. 11a, 11b, and 11c, the folded surface region F includes a section a1 where no segment is present and a section b1 where the number of stacked segments is uniform and where the number of stacked segments is 10 or more.

[0362] The folded surface region F may also include a layer number decreasing section b2 adjacent to the outer periphery of the electrode assembly 110, where the number of layers of the segment decreases toward the outer periphery. Preferably, the layer number uniform section b1 may be set as a welding target region.

[0363] In the folded surface region F, the ratio (a2 / c) of the height variable section a2 of the segment, based on the radial length (c) in which the segment exists, the ratio (b1 / c) of the uniform number of layers section b1 of the segment, and the preferred numerical ranges of 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.

[0364] The first current collecting plate 144 may be laser welded to the bent surface area F of the first uncoated portion 146a, and the second current collecting plate 145 may be laser welded to the bent surface area F of the second uncoated portion 146b. The welding method may be ultrasonic welding, resistance welding, spot welding, or the like.

[0365] Preferably, 50% or more of the welding region W of the first current collector 144 and the second current collector 145 may overlap with the uniform lamination number section b1 of the folded surface region F. Optionally, the remaining region of the welding region W may overlap with the reduced lamination number section b2 of the folded surface region F. It is more preferable that the entire welding region W overlap with the uniform lamination number section b1 in terms of high welding strength, low resistance at the welding interface, and prevention of damage to the separator and active material layer.

[0366] Preferably, the number of layers of the divided pieces may be 10 to 35 in the uniform layer number section b1 overlapping the welding area W and optionally in the reduced layer number section b2.

[0367] Alternatively, if the number of layers in the divided section of the layer count reduction section b2 overlapping the welding area W is less than 10, the laser output in the layer count reduction section b2 can be lower than the laser output in the uniform layer count section b1. That is, if the welding area W overlaps the uniform layer count section b1 and the layer count reduction section b2 at the same time, the laser output can be changed depending on the number of layers in the divided section. In this case, the weld strength in the uniform layer count section b1 can be greater than the weld strength in the layer count reduction section b2.

[0368] In the folded surface region F formed on the upper and lower parts of the electrode assembly 110, the radial lengths of the segment-omitted section a1 and / or the segment-height variable section a2 and / or the segment-height uniform section a3 may be the same or different.

[0369] In addition, the folded surface regions F formed on the upper and lower parts of the electrode assembly 110 may have a plane-symmetrical structure. Therefore, when the upper folded surface region F is projected onto the lower folded surface region F, they may substantially overlap each other.

[0370] In the electrode assembly 110, the height of the uncoated portion of the first portion B1 is relatively lower than the other portions. Also, as shown in Fig. 14, the bent length H of the segment closest to the core is smaller than the sum of the radial length R of the winding turn formed by the first portion B1 and 10% of the radius of the core 112.

[0371] Therefore, even if the divided piece included in the third portion B2 is bent toward the core side, 90% or more of the diameter of the core 112 of the electrode assembly 110 can be open to the outside. If the core 112 is not blocked, the electrolyte injection process can be performed without any problems, improving the efficiency of the electrolyte injection. In addition, a welding jig can be inserted through the core 112 to easily perform the welding process between the second current collector plate 145 and the battery housing 142.

[0372] If the width and / or height and / or spacing pitch of the segments are adjusted to satisfy the numerical ranges of the above-mentioned embodiments, when the segments are bent, the segments overlap each other to an extent that sufficient welding strength is ensured, and no open spaces (gaps) are formed in the bent surface area F.

[0373] Preferably, the first current collector plate 144 and the second current collector plate 145 may have an outer diameter that covers the ends of the folded segments (see 61 in FIG. 12) at the final winding turn of the first and second electrodes. In this case, the segments forming the folded surface area F can be welded while being uniformly pressed by the current collector plates, and the segments can be maintained in a tightly stacked state even after welding. A tightly stacked state means that there are substantially no gaps between the segments, as shown in FIG. 10a. The tightly stacked state contributes to reducing the resistance of the cylindrical battery 190 to a level suitable for fast charging (e.g., 4 mΩ) or less.

[0374] The sealing body 143 may include a cap plate 143a, a first gasket 143b having insulating properties and providing airtightness between the cap plate 143a and the battery housing 142, and a connecting plate 143c electrically and mechanically connected to the cap plate 143a.

[0375] The cap plate 143a is a component made of a conductive metal material and covers the upper opening of the battery housing 142. The cap plate 143a is electrically connected to the bent surface region F of the first electrode and is electrically insulated from the battery housing 142 via the first gasket 143b. Therefore, the cap plate 143a can function as a first electrode terminal (e.g., a positive electrode) of the cylindrical battery 190.

[0376] The cap plate 143a is placed on a beading portion 147 formed on the battery housing 142 and fixed by a crimping portion 148. A first gasket 143b may be interposed between the cap plate 143a and the crimping portion 148 to ensure airtightness of the battery housing 142 and to provide electrical insulation between the battery housing 142 and the cap plate 143a. The cap plate 143a may have a protrusion 143d formed to protrude upward from the center thereof.

[0377] The battery housing 142 is electrically connected to the bent surface area F of the second electrode. Therefore, the battery housing 142 has the same polarity as the second electrode. If the second electrode has a negative polarity, the battery housing 142 also has a negative polarity.

[0378] The battery housing 142 has a beading portion 147 and a crimping portion 148 at its upper end. The beading portion 147 is formed by pressing in around the outer periphery of the battery housing 142. The beading portion 147 prevents the electrode assembly 110 housed inside the battery housing 142 from slipping out of the upper opening of the battery housing 142, and can also function as a support on which the sealing body 143 is placed.

[0379] The second portion B3 of the first electrode does not include a segment and may be notched in the same structure as the first portion B1. Preferably, the inner circumferential surface of the beading portion 147 is spaced a predetermined distance from the winding turn formed by the second portion B3 of the first electrode. This is because the second portion B3 is notched like the first portion B1. More specifically, the lower end of the inner circumferential surface of the beading portion 147 is spaced a predetermined distance from the winding turn formed by the second portion B3 of the first electrode. Furthermore, because the uncoated portion of the second portion B3 has a low height, the winding turn of the second portion B3 is substantially unaffected even when the battery housing 142 is pressed from the outside to form the beading portion 147. Therefore, the winding turn of the second portion B3 is not compressed by other components such as the beading portion 147, which prevents partial deformation of the electrode assembly 110 and internal short circuits in the cylindrical battery 190.

[0380] Preferably, the relationship D1≦D2 can be satisfied, where D1 is the pressing depth of the beading portion 147 and D2 is 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. In this case, when the battery housing 142 is pressed to form the beading portion 147, damage to the wound turns formed by the second portion B3 is substantially prevented.

[0381] The crimping portion 148 is formed on the upper portion of the beading portion 147. The crimping portion 148 is extended and bent to enclose the outer circumferential surface of the cap plate 143a disposed on the beading portion 147 and a part of the upper surface of the cap plate 143a.

[0382] The cylindrical battery 190 may further include a first current collector 144 and / or a second current collector 145 and / or an insulator 146 .

[0383] The first current collecting plate 144 is coupled to the upper part of the electrode assembly 110. The first current collecting plate 144 is made of a conductive metal material such as aluminum, copper, steel, nickel, etc., and is electrically connected to the bent surface region F of the first electrode. The electrical connection may be made by welding. A lead 149 may be connected to the first current collecting plate 144. The lead 149 may extend upwardly of the electrode assembly 110 and be coupled to the connection plate 143c, or may be directly coupled to the lower surface of the cap plate 143a. The lead 149 may be coupled to other components by welding.

[0384] Preferably, the first current collector 144 may 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.

[0385] The first current collecting plate 144 and the bent surface region F of the first electrode may be joined by, for example, laser welding. Laser welding may be performed by partially melting the base material of the current collecting plate. In a modified example, the first current collecting plate 144 and the bent surface region F may be welded together using solder. In this case, the solder may have a lower melting point than the first current collecting plate 144 and the first uncoated portion 146a. Laser welding may be replaced by resistance welding, ultrasonic welding, spot welding, etc.

[0386] A second current collecting plate 145 may be coupled to the lower surface of the electrode assembly 110. One surface of the second current collecting plate 145 may be coupled to the folded surface region F of the second electrode by welding, and the other surface may be coupled to the inner bottom surface of the battery housing 142 by welding. The coupling structure between the second current collecting plate 145 and the folded surface region F of the second electrode may be substantially the same as the coupling structure between the first current collecting plate 144 and the folded surface region F of the first electrode.

[0387] The insulator 146 may cover the first current collector 144. By covering the first current collector 144 on the upper surface of the first current collector 144, the insulator 146 can prevent direct contact between the first current collector 144 and the inner circumferential surface of the battery housing 142.

[0388] The insulator 146 has a lead hole 151 through which the lead 149 extending upward from the first current collector plate 144 is drawn out. The lead 149 is drawn out upward through the lead hole 151 and is coupled to the lower surface of the connecting plate 143c or the lower surface of the cap plate 143a.

[0389] The peripheral region of the insulator 146 may be interposed between the first current collector plate 144 and the beading portion 147 to fix the combination of the electrode assembly 110 and the first current collector plate 144. This limits the movement of the combination of the electrode assembly 110 and the first current collector plate 144 in the height direction of the battery 140, thereby improving the assembly stability of the battery 140.

[0390] The insulator 146 may be made of an insulating polymer resin. For example, the insulator 146 may be made of polyethylene, polypropylene, polyimide, or polybutylene terephthalate.

[0391] The battery housing 142 may further include a venting portion 152 formed on its bottom surface. The venting portion 152 corresponds to a region on the bottom surface of the battery housing 142 that is thinner than the surrounding region. The venting portion 152 is structurally weaker than the surrounding region. Therefore, if an abnormality occurs in the cylindrical battery 190 and the internal pressure increases above a certain level, the venting portion 152 may burst, allowing the gas generated inside the battery housing 142 to be released to the outside. The internal pressure at which the venting portion 152 bursts is approximately 15 kgf / cm. 2 ~35kgf / cm 2 It could be.

[0392] The vents 152 may be formed continuously or discontinuously in a circular pattern on the underside of the battery housing 142. Alternatively, the vents 152 may be formed in a linear pattern or other patterns.

[0393] FIG. 18 is a cross-sectional view of a cylindrical battery 200 according to another embodiment of the present invention, taken along the Y-axis direction.

[0394] Referring to FIG. 18, a cylindrical battery 200 has substantially the same electrode assembly structure as the cylindrical battery 190 shown in FIG. 17, but differs in that other structures except for the electrode assembly have been changed.

[0395] Specifically, the cylindrical battery 200 includes a battery housing 171 having a rivet terminal 172 extending therethrough. The rivet terminal 172 is attached through a through-hole formed in the closed surface (top surface in the drawing) of the battery housing 171. The rivet terminal 172 is riveted into the through-hole of the battery housing 171 with a second gasket 173 made of an insulating material interposed therebetween. The rivet terminal 172 is exposed outward in the direction opposite to the direction of gravity.

[0396] The rivet terminal 172 includes a terminal exposure portion 172a and a terminal insertion portion 172b. The terminal exposure portion 172a is exposed to the outside of the closed surface of the battery housing 171. The terminal exposure portion 172a may be located approximately at the center of the closed surface of the battery housing 171. The maximum diameter of the terminal exposure portion 172a may be larger than the maximum diameter of the through-hole formed in the battery housing 171. The terminal insertion portion 172b may penetrate approximately the center of the closed surface of the battery housing 171 to be electrically connected to the uncoated portion 146a of the first electrode. The lower peripheral edge of the terminal insertion portion 172b may be rivet-connected to the inner surface of the battery housing 171. That is, the lower peripheral edge of the terminal insertion portion 172b may be bent toward the inner surface of the battery housing 171. A flat portion 172c may be included on the inner side of the lower peripheral edge of the terminal insertion portion 172b. The maximum diameter of the bottom of the riveted terminal insertion portion 172b may be larger than the maximum diameter of the through hole in the battery housing 171.

[0397] The flat portion 172c of the terminal insertion portion 172b may be welded to the center of the first current collecting plate 144 connected to the bent surface region F of the first electrode. Laser welding is preferred as the welding method, but other welding methods such as ultrasonic welding may be used instead.

[0398] An insulator 174 made of an insulating material may be interposed between the first current collecting plate 144 and the inner surface of the battery housing 171. The insulator 174 covers the upper portion of the first current collecting plate 144 and the upper peripheral edge portion of the electrode assembly 110. This prevents the second portion B3 of the electrode assembly 110 from coming into contact with the inner surface of the battery housing 171, which has the opposite polarity, and causing a short circuit.

[0399] The thickness of the insulator 174 corresponds to or is slightly larger than the distance between the upper surface of the first current collector 144 and the inner surface of the closed portion of the battery housing 171. Therefore, the insulator 174 can contact the upper surface of the first current collector 144 and the inner surface of the closed portion of the battery housing 171.

[0400] The terminal insertion portion 172b of the rivet terminal 172 may be welded to the first current collecting plate 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 riveting portion at the lower end of the terminal insertion portion 172b. Preferably, the through hole may expose the lower portion of the terminal insertion portion 172b and the second gasket 173.

[0401] The second gasket 173 is interposed between the battery housing 171 and the rivet terminal 172 to prevent electrical contact between the battery housing 171 and the rivet terminal 172, which have opposite polarities. This allows the upper surface of the battery housing 171, which has a substantially flat shape, to function as a second electrode terminal (e.g., a negative electrode) of the cylindrical battery 200.

[0402] The second gasket 173 includes a gasket exposing portion 173a and a gasket inserting portion 173b. The gasket exposing portion 173a is interposed between the terminal exposing portion 172a of the rivet terminal 172 and the battery housing 171. The gasket inserting portion 173b is interposed between the terminal inserting portion 172b of the rivet terminal 172 and the battery housing 171. The gasket inserting portion 173b may be deformed during riveting of the terminal inserting portion 172b, thereby adhering closely to the inner surface of the battery housing 171. The second gasket 173 may be made of, for example, an insulating polymer resin.

[0403] The gasket exposing portion 173a of the second gasket 173 may extend to cover the outer peripheral surface of the terminal exposing portion 172a of the rivet terminal 172. When the second gasket 173 covers the outer peripheral surface of the rivet terminal 172, it is possible to prevent a short circuit from occurring during the process of connecting an electrical connection component such as a bus bar to the upper surface of the battery housing 171 and / or the rivet terminal 172. Although not shown, the gasket exposing portion 173a may extend to cover not only the outer peripheral surface of the terminal exposing portion 172a but also a portion of the upper surface.

[0404] When the second gasket 173 is made of a polymer resin, the second gasket 173 may be joined to the battery housing 171 and the rivet terminal 172 by heat sealing. In this case, the airtightness at the joining interface between the second gasket 173 and the rivet terminal 172 and at the joining interface between the second gasket 173 and the battery housing 171 is strengthened. Meanwhile, when the gasket exposed portion 173a of the second gasket 173 has a shape that extends to the upper surface of the terminal exposed portion 172a, the rivet terminal 172 may be joined integrally with the second gasket 173 by insert injection molding.

[0405] On the upper surface of the battery housing 171, a region 175 other than the region occupied by the rivet terminal 172 and the second gasket 173 corresponds to a second electrode terminal having a polarity opposite to that of the rivet terminal 172.

[0406] The second current collecting plate 176 is coupled to the lower part of the electrode assembly 141. The second current collecting plate 176 is made of a conductive metal material such as aluminum, steel, copper, or nickel, and is electrically connected to the bent surface region F of the second electrode.

[0407] Preferably, second current collecting plate 176 is electrically connected to battery housing 171. Therefore, second current collecting plate 176 may be fixed with at least a portion of its peripheral edge interposed between the inner surface of battery housing 171 and first gasket 178b. As an example, at least a portion of the peripheral edge of second current collecting plate 176 may be fixed to beading portion 180 by welding while being supported on a lower end surface of beading portion 180 formed at the lower end of battery housing 171. In a modified example, at least a portion of the peripheral edge of second current collecting plate 176 may be directly welded to the inner wall surface of battery housing 171.

[0408] Preferably, the second current collecting plate 176 and the folded surface region F of the second electrode may be joined by, for example, laser welding. In addition, the welded portion between the second current collecting plate 176 and the folded surface region F is spaced a predetermined distance from the inner circumferential surface of the beading portion 180 toward the core C.

[0409] The sealing body 178, which seals the lower open end of the battery housing 171, includes a cap plate 178a and a first gasket 178b. The first gasket 178b electrically isolates the cap plate 178a from the battery housing 171. The crimping portion 181 secures the periphery of the cap plate 178a to the first gasket 178b. The cap plate 178a is provided with a vent portion 179. The configuration of the vent portion 179 is substantially the same as in the above-described embodiment (variant). The lower surface of the cap plate 178a may be located higher than the lower end of the crimping portion 181. In this case, a space is formed below the cap plate 178a, allowing for smooth venting. This is particularly useful when the cylindrical battery 200 is installed with the crimping portion 181 facing the direction of gravity.

[0410] Preferably, the cap plate 178a is made of a conductive metal material. However, since the first gasket 178b is interposed between the cap plate 178a and the battery housing 171, the cap plate 178a does not have electrical polarity. The sealing body 178 seals the open end of the lower part of the battery housing 171 and mainly functions to discharge gas when the internal pressure of the battery 200 increases above a critical value. The critical value of the internal pressure is 15 kgf / cm. 2 ~35kgf / cm 2 is.

[0411] Preferably, the rivet terminal 172 electrically connected to the bent surface region F of the first electrode is used as the first electrode terminal. Furthermore, a portion 175 of the upper surface of the battery housing 171, excluding the rivet terminal 172, electrically connected to the bent surface region F of the second electrode through the second current collector plate 176 is used as a second electrode terminal having the opposite polarity to the first electrode terminal. When two electrode terminals are located on the upper portion of the cylindrical battery 200, electrical connection components such as bus bars can be disposed on only one side of the cylindrical battery 200. This simplifies the battery pack structure and improves energy density. Furthermore, the portion 175 used as the second electrode terminal has a substantially flat shape, ensuring a sufficient contact area for connecting electrical connection components such as bus bars. This allows the cylindrical battery 200 to reduce resistance at the contact points of the electrical connection components to a desirable level.

[0412] FIG. 19 is a cross-sectional view of a cylindrical battery 210 according to yet another embodiment of the present invention, taken along the Y-axis direction.

[0413] 19, a cylindrical battery 210 includes the electrode assembly 100 shown in FIG. 13, and other configurations except for the electrode assembly 100 are substantially the same as the cylindrical battery 190 shown in FIG. 17. Therefore, the configurations described with reference to FIGS. 13 and 17 can be applied substantially in the same manner to this embodiment.

[0414] Preferably, the first uncoated portion 146a and the second uncoated portion 146b of the electrode assembly 100 include a plurality of segment pieces 61. The segment pieces 61 are bent in the radial direction of the electrode assembly 100, for example, from the outer periphery toward the core. In this case, the uncoated portions of the first portion B1 and the second portion B3 of the first uncoated portion 146a are lower in height than the other portions and do not include segment pieces, so they are not substantially bent. The same is true for the second uncoated portion 146b.

[0415] In this embodiment, the folded surface region F formed by the segment 61 may include, from the core side to the outer periphery, a segment-free section a1, a segment-height variable section a2, and a segment-height uniform section a3. However, because the plain portion of the second portion B3 is not folded, the radial length of the folded surface region F may be shorter than in the above-described embodiment.

[0416] As shown in FIGS. 11a, 11b, and 11c, the folded surface region F includes a section a1 where no segment is present and a section b1 where the number of stacked segments is uniform and where the number of stacked segments is 10 or more.

[0417] The folded surface region F may also include a layer count decreasing section b2 in which the number of layers of the segment decreases toward the outer periphery adjacent to the winding turns of the second portion B3 of the electrode assembly 100. Preferably, the layer count uniform section b1 may be set as a welding target region.

[0418] In the folded surface region F, the ratio (a2 / c) of the height variable section a2 of the segment, based on the radial length (c) in which the segment exists, the ratio (b1 / c) of the uniform number of layers section b1 of the segment, and the preferred numerical ranges of 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.

[0419] The first current collecting plate 144 may be welded to the bent surface area F of the first uncoated portion 146a, and the second current collecting plate 145 may be welded to the bent surface area F of the second uncoated portion 146b.

[0420] The overlapping relationship between the uniform stack count section b1 and the reduced stack count section b2 and the welding area W, the outer diameters of the first current collector plate 144 and the second current collector plate 145, and the configuration in which the first portion B1 does not block the core are essentially as described above.

[0421] On the other hand, the second portion B3 does not include a divided segment, and the height of the uncoated portion is lower than that of the divided segment of the third portion B2. Therefore, when the divided segment of the third portion B2 is bent, the second portion B3 is not substantially bent. In addition, the wound turns of the second portion B3 are sufficiently spaced apart from the beading portion 147, which solves the problem of the wound turns of the second portion B3 being damaged when the beading portion 147 is pressed in.

[0422] FIG. 20 is a cross-sectional view of a cylindrical battery 220 according to yet another embodiment of the present invention, taken along the Y-axis direction.

[0423] 20, a cylindrical battery 220 includes the electrode assembly 100 shown in FIG. 13, and other configurations except for the electrode assembly 100 are substantially the same as the cylindrical battery 200 shown in FIG. 18. Therefore, the configurations described with reference to FIGS. 13 and 18 can be applied substantially similarly to this embodiment.

[0424] Preferably, the first uncoated portion 146a and the second uncoated portion 146b of the electrode assembly 100 include a plurality of divided segments 61. The divided segments 61 are bent from the outer periphery of the electrode assembly 100 toward the core to form a folded surface region F. In this case, the first portion B1 and the second portion B3 of the first uncoated portion 146a are not substantially bent toward the core because the height of the uncoated portion is lower than the other portions and they do not include divided segments. The same applies to the second uncoated portion 146b.

[0425] 19, the folded surface region F may include, from the core side to the outer periphery, a segment-free section a1, a segment-height variable section a2, and a segment-height uniform section a3. However, because the plain portion of the second portion B3 is not folded, the radial length of the folded surface region F may be shorter than in the above-described embodiment.

[0426] As shown in FIGS. 11a, 11b, and 11c, the folded surface region F includes a section a1 where no segment is present and a section b1 where the number of stacked segments is uniform and where the number of stacked segments is 10 or more.

[0427] The folded surface region F may also include a layer count decreasing section b2 in which the number of layers of the segment decreases toward the outer periphery adjacent to the winding turns of the second portion B3 of the electrode assembly 100. Preferably, the layer count uniform section b1 may be set as a welding target region.

[0428] In the folded surface region F, the ratio (a2 / c) of the height variable section a2 of the segment, based on the radial length (c) in which the segment exists, the ratio (b1 / c) of the uniform number of layers section b1 of the segment, and the preferred numerical ranges of 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.

[0429] The first current collector 144 may be welded to the bent surface area F of the first uncoated portion 146a, and the second current collector 176 may be welded to the bent surface area F of the second uncoated portion 146b.

[0430] The overlapping relationship between the uniform stack count section b1 and the reduced stack count section b2 and the welding area W, the outer diameters of the first current collector plate 144 and the second current collector plate 176, and the configuration in which the first portion B1 does not block the core are essentially as described above.

[0431] In the above-described embodiment (variant), the first current collector plate 144 and the second current collector plate 176 included in the cylindrical batteries 200, 220 including the rivet terminals 172 may have an improved structure as shown in Figures 21 and 22.

[0432] The improved structure of the first current collector plate 144 and the second current collector plate 176 can contribute to lowering the resistance of the cylindrical battery, improving vibration resistance, and increasing the energy density. The first current collector plate 144 and the second current collector plate 176 are particularly effective when applied to large cylindrical batteries with a height-to-diameter ratio of greater than 0.4.

[0433] FIG. 21 is a top view showing the structure of a first current collector plate 144 according to an embodiment of the present invention.

[0434] 20 and 21, the first current collecting plate 144 may include a peripheral portion 144a, a first non-coating portion coupling portion 144b, and a terminal coupling portion 144c. The peripheral portion 144a is disposed on the upper portion of the electrode assembly 100. The peripheral portion 144a has an empty space S therein. open The peripheral portion 144a may have a substantially rim shape formed thereon. Although the drawings only show the case where the peripheral portion 144a has a substantially circular rim shape, the present invention is not limited thereto. Unlike the illustrations, the peripheral portion 144a may have a substantially square rim shape, a hexagonal rim shape, an octagonal rim shape, or other rim shapes. The number of peripheral portions 144a may be increased to two or more. In this case, another rim-shaped peripheral portion may be included inside the peripheral portion 144a.

[0435] The terminal coupling portion 144c may have a diameter equal to or larger than the diameter of the flat portion 172c formed on the bottom surface of the rivet terminal 172 to ensure a welding area for coupling with the flat portion 172c formed on the bottom surface of the rivet terminal 172.

[0436] The first non-coating portion coupling portion 144b extends inward from the peripheral portion 144a and is coupled to the bent surface region F of the non-coating portion 146a by welding. The terminal coupling portion 144c is spaced apart from the first non-coating portion coupling portion 144b and is positioned inside the peripheral portion 144a. The terminal coupling portion 144c may be coupled to a rivet terminal 172 by welding. The terminal coupling portion 144c is, for example, in an inner space S surrounded by the peripheral portion 144a. openThe terminal coupling portion 144c may be provided at a position corresponding to a hole formed in the core C of the electrode assembly 100. The terminal coupling portion 144c may be configured to cover the hole formed in the core C of the electrode assembly 100 so that the hole formed in the core C of the electrode assembly 100 is not exposed to the outside of the terminal coupling portion 144c. Therefore, the terminal coupling portion 144c may have a diameter or width larger than the hole formed in the core C of the electrode assembly 100.

[0437] The first non-coating portion coupling portion 144b and the terminal coupling portion 144c may be spaced apart and indirectly coupled via the peripheral portion 144a. In this manner, the first current collecting plate 144 has a structure in which the first non-coating portion coupling portion 144b and the terminal coupling portion 144c are not directly coupled but are coupled via the peripheral portion 144a. This allows for dispersion of impacts applied to the coupling portion between the first non-coating portion coupling portion 144b and the first non-coating portion 146a and the coupling portion between the terminal coupling portion 144c and the rivet terminal 172 when shock and / or vibration occurs to the cylindrical battery 220. While four first non-coating portion coupling portions 144b are shown in the drawings, the present invention is not limited thereby. The number of first non-coating portion coupling portions 144b may be determined based on 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 It can be determined in various ways, taking into consideration the above.

[0438] The first current collecting plate 144 may further include a bridge portion 144d extending inward from the peripheral portion 144a and connecting to the terminal connecting portion 144c. The bridge portion 144d may have at least a portion having a smaller cross-sectional area than the first non-coating portion connecting portion 144b and the peripheral portion 144a. For example, the bridge portion 144d may have at least a portion having a smaller width and / or thickness than the first non-coating portion connecting portion 144b. In this case, electrical resistance increases in the bridge portion 144d. As a result, when current flows through the bridge portion 144d, the relatively large resistance causes a portion of the bridge portion 144d to melt due to overcurrent heating, irreversibly interrupting the overcurrent. The cross-sectional area of ​​the bridge portion 144d may be adjusted to an appropriate level in consideration of this overcurrent interruption function.

[0439] The bridge portion 144d may include a tapered portion 144e whose width gradually narrows from the inner surface of the peripheral portion 144a toward the terminal coupling portion 144c. The tapered portion 144e improves the rigidity of the component at the connection portion between the bridge portion 144d and the peripheral portion 144a. The tapered portion 144e allows, for example, a transfer device and / or a worker to grip the tapered portion 144e during the manufacturing process of the cylindrical battery 220, thereby allowing the first current collecting plate 144 and / or the combination of the first current collecting plate 144 and the electrode assembly 100 to be easily and safely transported. That is, the tapered portion 144e can prevent product defects caused by gripping portions to be welded to other components, such as the first uncoated portion coupling portion 144b and the terminal coupling portion 144c.

[0440] The first non-coating portion joining portions 144b may be provided in plurality. The first non-coating portion joining portions 144b may be disposed at equal intervals along the extension direction of the peripheral portion 144a. The first non-coating portion joining portions 144b may have substantially the same extension length. The first non-coating portion joining portions 144b may be joined to the folded surface region F of the non-coating portion 146a by laser welding. The welding may be substituted by ultrasonic welding, spot welding, etc.

[0441] The welding pattern 144f formed by welding the first non-coating portion joining portion 144b and the bent surface region F may have a structure extending along the radial direction of the electrode assembly 100. The welding pattern 144f may be an array of lines or dots.

[0442] The welding pattern 144f corresponds to a welding region. Therefore, it is preferable that the welding pattern 144f overlaps with the uniform layer count section b1 of the folded surface region F by 50% or more. The welding pattern 144f that does not overlap with the uniform layer count section b1 may overlap with the reduced layer count section b2. More preferably, the entire welding pattern 144f may overlap with the uniform layer count section b1 of the folded surface region F. It is preferable that the uniform layer count section b1 and optionally the reduced layer count section b2 of the folded surface region F below the point where the welding pattern 144f is formed have a number of laminated sections of 10 or more.

[0443] The terminal coupling portion 144c may be disposed to be surrounded by the plurality of first non-coating portion coupling portions 144b. The terminal coupling portion 144c may be coupled to the flat portion 172c of the rivet terminal 172 by welding. The bridge portion 144d may be located between a pair of adjacent first non-coating portion coupling portions 144b. In this case, the distance from the bridge portion 144d to one of the pair of first non-coating portion coupling portions 144b along the extension direction of the peripheral portion 144a may be approximately the same as the distance from the bridge portion 144d to the other of the pair of first non-coating portion coupling portions 144b along the extension direction of the peripheral portion 144a. The cross-sectional area of ​​each of the plurality of first non-coating portion coupling portions 144b may be approximately the same. The width and thickness of each of the plurality of first non-coating portion coupling portions 144b may be approximately the same.

[0444] Although not shown, a plurality of bridge portions 144d may be provided. Each of the plurality of bridge portions 144d may be disposed between an adjacent pair of first non-coating portion joining portions 144b. The plurality of bridge portions 144d may be disposed at substantially equal intervals from one another along the extension direction of the peripheral portion 144a. The distance from each of the plurality of bridge portions 144d to one of the adjacent pair of first non-coating portion joining portions 144b along the extension direction of the peripheral portion 144a may be substantially the same as the distance to the other first non-coating portion joining portion 144b.

[0445] As described above, when a plurality of first uncoated portion joining portions 144b and / or bridge portions 144d are provided, if the distance between the first uncoated portion joining portions 144b and / or the distance between the bridge portions 144d and / or the distance between the first uncoated portion joining portions 144b and the bridge portions 144d are constant, a current can smoothly flow from the first uncoated portion joining portions 144b to the bridge portions 144d or from the bridge portions 144d to the first uncoated portion joining portions 144b.

[0446] The bridge portion 144d may include a notch N formed to partially reduce the cross-sectional area of ​​the bridge portion 144d. The adjustment of the cross-sectional area of ​​the notch N can be achieved, for example, by partially reducing the width and / or thickness of the bridge portion 144d. When the notch N is provided, the electrical resistance in the region where the notch N is formed increases, thereby enabling rapid current interruption when an overcurrent occurs.

[0447] The notched portion N is preferably provided in a region corresponding to a uniform lamination section of the electrode assembly 100 to prevent foreign matter generated during breakage from entering the electrode assembly 100. This is because the number of laminations of the uncoated portion 146a is maximized in this region, allowing the overlapping laminations to function as a mask.

[0448] The notched portion N may be wrapped with insulating tape, so that heat generated at the notched portion N is not dissipated to the outside, and therefore the notched portion N breaks more quickly when an overcurrent flows through the bridge portion 144d.

[0449] FIG. 22 is a top view showing the structure of a second current collector plate 176 according to one embodiment of the present invention.

[0450] 20 and 22, the second current collecting plate 176 is disposed at the bottom of the electrode assembly 100. The second current collecting plate 176 may be configured to electrically connect the uncoated portion 146b of the electrode assembly 100 to the battery housing 171. The second current collecting plate 176 is made of a conductive metal material and is electrically connected to the bent surface region F of the uncoated portion 146b. The second current collecting plate 176 is also electrically connected to the battery housing 171. A peripheral portion of the second current collecting plate 176 may be interposed and fixed between the inner surface of the battery housing 171 and the first gasket 178b. Specifically, a peripheral portion of the second current collecting plate 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 instead, the peripheral portion of the second current collecting plate 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.

[0451] The second current collecting plate 176 may include a support portion 176a disposed at a lower portion of the electrode assembly 100, a second non-coating portion coupling portion 176b extending from the support portion 176a substantially along the radial direction of the electrode assembly 100 and coupled to the bent surface region F of the non-coating portion 146b, and a housing coupling portion 176c extending from the support portion 176a at an angle substantially toward the inner surface of the battery housing 171 relative to the radial direction of the electrode assembly 100 and coupled to the inner surface. The second non-coating portion coupling portion 176b and the housing coupling portion 176c are indirectly coupled to each other via the support portion 176a and are not directly coupled to each other. Therefore, when an external impact is applied to the cylindrical battery 220 according to one embodiment of the present invention, damage to the coupling portions between the second current collecting plate 176 and the electrode assembly 100 and between the second current collecting plate 176 and the battery housing 171 can be minimized. However, the second current collecting plate 176 according to an embodiment of the present invention is not limited to having a structure in which the second uncoated portion coupling portion 176b and the housing coupling portion 176c are indirectly coupled to each other. For example, the second current collecting plate 176 may have a structure without the support portion 176a that indirectly couples the second uncoated portion coupling portion 176b and the housing coupling portion 176c and / or a structure in which the uncoated portion 146b and the housing coupling portion 176c are directly coupled to each other.

[0452] The support portion 176a and the second non-coating portion joining portion 176b are disposed at the bottom of the electrode assembly 100. The second non-coating portion joining portion 176b is joined to the folded surface region F of the non-coating portion 146b. Not only the second non-coating portion joining portion 176b but also the support portion 176a may be joined to the non-coating portion 146b. The second non-coating portion joining portion 176b and the folded surface region F of the non-coating portion 146b may be joined by laser welding. Welding may be replaced by ultrasonic welding, spot welding, or the like. If a beading portion 180 is formed on the battery housing 171, the support portion 176a and the second non-coating portion joining portion 176b are located above the beading portion 180.

[0453] The support portion 176a has a current collecting plate hole 176d formed at a position corresponding to a hole formed in the core C of the electrode assembly 100. The core C of the electrode assembly 100 and the current collecting plate hole 176d, which are in communication with each other, can function as a passage for inserting a welding rod or irradiating a laser beam for welding between the rivet terminal 172 and the terminal coupling portion 144c of the first current collecting plate 144.

[0454] The current collecting plate hole 176d has a radius r c 0.5r to c The radius of the current collecting plate hole 176d may be 0.5r or more. c ~1.0r c In this case, when venting occurs in the cylindrical battery 220, the separator and the electrode winding structure near the core C of the electrode assembly 100 are prevented from being pushed out of the core C by the vent pressure. c When the core C is larger than 1 / 2, the core C is opened to the maximum extent, which makes it easier to inject the electrolyte in the electrolyte injection step.

[0455] When a plurality of second uncoated portion coupling portions 176b are provided, the plurality of second uncoated portion coupling portions 176b may extend radially from the support portion 176a of the second current collector plate 176 toward the sidewall of the battery housing 171. The plurality of second uncoated portion coupling portions 176b may be spaced apart from one another along the periphery of the support portion 176a.

[0456] A plurality of the housing coupling portions 176c may be provided. In this case, the plurality of housing coupling portions 176c may extend radially from the center of the second current collecting plate 176 toward the sidewall of the battery housing 171. This allows electrical connection between the second current collecting plate 176 and the battery housing 171 at multiple points. By coupling for electrical connection at multiple points, the coupling area can be maximized and electrical resistance can be minimized. The plurality of housing coupling portions 176c may be spaced apart from one another along the periphery of the support portion 176a. At least one housing coupling portion 176c may be located between adjacent second non-coating portion coupling portions 176b. The plurality of housing coupling portions 176c may be coupled to the inner surface of the battery housing 171, for example, to the beading portion 180. The housing coupling portion 176c may be coupled to the lower surface of the beading portion 180 by laser welding. The welding may be substituted by ultrasonic welding, spot welding, or the like. By welding a plurality of housing coupling portions 176c onto the beading portion 180 in this manner, the current path is dispersed radially, thereby limiting the resistance level of the cylindrical battery 220 to approximately 4 mΩ or less. In addition, by forming the lower surface of the beading portion 180 to extend in a direction approximately parallel to the upper surface of the battery housing 171, i.e., in a direction approximately perpendicular to the sidewall of the battery housing 171, and forming the housing coupling portions 176c to extend in the same direction, i.e., 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 portions of the beading portion 180 in this manner, welding between the two components is performed smoothly, thereby improving the bonding strength between the two components and minimizing the increase in resistance at the bonding site.

[0457] The housing coupling portion 176c may include a contact portion 176e coupled to the inner surface of the battery housing 171, and a coupling portion 176f connecting the support portion 176a and the contact portion 176e.

[0458] The contact portion 176e is coupled to an inner surface of the battery housing 171. If a beading portion 180 is formed in the battery housing 171, the contact portion 176e may be coupled to the beading portion 180 as described above. More specifically, the contact portion 176e may be electrically coupled to a flat portion formed on the lower surface of the beading portion 180 formed in the battery housing 171, and may be interposed between the lower surface of the beading portion 180 and the first gasket 178b. In this case, for stable contact and coupling, the contact portion 176e may extend a predetermined length in the beading portion 180 along the circumferential direction of the battery housing 171.

[0459] The connecting portion 176f may be bent at an obtuse angle. The bending point may be higher than 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 may be divided into a lower portion and an upper portion based on the bending point, and the length of the lower portion may be greater than that of the upper portion. In addition, the inclination angle based on the surface of the support portion 176a may be greater at the lower portion at the bending point than at the upper portion. When the connecting portion 176f is bent, it can buffer 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 bending point of the connecting portion 176f moves upward, deforming the connecting portion 176f, thereby buffering stress.

[0460] Meanwhile, the maximum distance from the center of the second current collector plate 176 to the end of the second uncoated portion joining portion 176b along the radial direction of the electrode assembly 100 is preferably equal to 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 uncoated portion joining portion 176b from pressing against the end of the electrode assembly 100 during a sizing process in which the battery housing 171 is compressed in the height direction.

[0461] The second non-coating portion joining portion 176b includes holes 176g. The holes 176g can be used as passages for electrolyte movement. A welding pattern 176h formed by welding the second non-coating portion joining portion 176b to the bent surface region F can have a structure extending along the radial direction of the electrode assembly 100. The welding pattern 176h can be an array of lines or dots.

[0462] The welding pattern 176h corresponds to a welding region. Therefore, it is preferable that the welding pattern 176h overlaps with the uniform lamination number section b1 of the folded surface region F located at the bottom of the electrode assembly 100 by 50% or more. The welding pattern 176h that does not overlap with the uniform lamination number section b1 may overlap with the reduced lamination number section b2. More preferably, the entire welding pattern 176h may overlap with the uniform lamination number section b1 of the folded surface region F. It is preferable that the uniform lamination number section b1 and, optionally, the reduced lamination number section b2 of the folded surface region F located above the point where the welding pattern 176h is formed have a divisional section with a lamination number of 10 or more.

[0463] The first current collector plate 144 and the second current collector plate 176 have different outer diameters. The outer diameter is the outer diameter of the contact area between the folded surface region F and the current collector plate. The outer diameter is defined as the maximum distance between two points where a line passing through the center of the core C of the electrode assembly intersects with the edge of the contact area. Because the second current collector plate 176 is located inside the beading portion, its outer diameter is smaller than that of the first current collector plate 144. In addition, the length of the welding pattern 144f of the first current collector plate 144 is longer than the length of the welding pattern 176h of the second current collector plate 176. Preferably, the welding pattern 144f and the welding pattern 176h may extend radially outward from substantially the same point relative to the center of the core C.

[0464] The cylindrical batteries 200 and 220 according to the present invention may be electrically connected at the top.

[0465] Fig. 23 is a top view showing a state in which a plurality of cylindrical batteries 200 are electrically connected, and Fig. 24 is a partially enlarged view of Fig. 23. The cylindrical battery 200 can be replaced with a cylindrical battery 220 having a different structure.

[0466] 23 and 24, a plurality of cylindrical batteries 200 may be connected in series and parallel at the top of the cylindrical batteries 200 using bus bars 210. The number of cylindrical batteries 200 may be increased or decreased depending on the capacity of the battery pack.

[0467] In each cylindrical battery 200, the rivet terminal 172 may have a positive polarity, and the flat surface 171a around the rivet terminal 172 of the battery housing 171 may have a negative polarity. Of course, the opposite is also possible.

[0468] Preferably, the cylindrical batteries 200 may be arranged in a plurality of rows and columns. In the drawings, columns are arranged in the vertical direction, and rows are arranged in the horizontal direction. Furthermore, to maximize space efficiency, the cylindrical batteries 200 may be arranged in the closest packing structure. The closest packing structure is formed when an equilateral triangle is drawn when the centers of the rivet terminals 172 exposed on the outside of the battery housing 171 are connected to each other. Preferably, the bus bars 210 connect the cylindrical batteries 200 arranged in the same column in parallel with each other, and connect the cylindrical batteries 200 arranged in two adjacent columns in series with each other.

[0469] Preferably, the bus bar 210 may include a body portion 211, a plurality of first bus bar terminals 212, and a plurality of second bus bar terminals 213 for series and parallel connection.

[0470] The body portion 211 may extend along the row of cylindrical batteries 200 between adjacent rivet terminals 172. Alternatively, the body portion 211 may extend along the row of cylindrical batteries 200 but may be bent regularly, such as in a zigzag shape.

[0471] The plurality of first bus bar terminals 212 may extend from one side of the body portion 211 and be electrically coupled to the rivet terminals 172 of the cylindrical battery 200 located on the one side. The electrical coupling between the first bus bar terminals 212 and the rivet terminals 172 may be performed by laser welding, ultrasonic welding, or the like.

[0472] The plurality of second bus bar terminals 213 may extend from the other side of the body portion 211 and be electrically coupled to the flat surface 171a around the rivet terminals 172 located on the other side. The electrical coupling between the second bus bar terminals 213 and the flat surface 171a may be performed by laser welding, ultrasonic welding, or the like.

[0473] Preferably, the body portion 211, the plurality of first bus bar terminals 212, and the plurality of second bus bar terminals 213 may be formed from a single conductive metal plate. The metal plate may be, for example, an aluminum plate or a copper plate, but the present invention is not limited thereto. Alternatively, the body portion 211, the plurality of first bus bar terminals 212, and the second bus bar terminals 213 may be manufactured as separate pieces and then joined together by welding or the like.

[0474] The cylindrical battery 200 according to the embodiment of the present invention has a structure in which resistance is minimized by expanding the welding area through the bent surface area F, multiplexing the current paths using the second current collector plate 176, and minimizing the length of the current paths. The AC resistance of the cylindrical battery 200 measured by a resistance meter between the positive and negative electrodes, i.e., between the rivet terminal 172 and the surrounding flat surface 171a, may be approximately 4 mΩ or less, which is suitable for fast charging.

[0475] In the cylindrical battery 200 according to one embodiment of the present invention, the rivet terminal 172 having a positive polarity and the flat surface 171a having a negative polarity are positioned in the same direction, so that electrical connection between the cylindrical batteries 200 can be easily achieved using the bus bar 210.

[0476] In addition, since the rivet terminal 172 of the cylindrical battery 200 and the surrounding flat surface 171a have a large area, the connection area of ​​the bus bar 210 can be sufficiently secured, thereby sufficiently reducing the resistance of the battery pack including the cylindrical battery 200.

[0477] In addition, since electrical wiring can be performed on the top of the cylindrical battery 200, the energy density per unit volume of the battery module / pack can be maximized.

[0478] The cylindrical battery according to the above-described embodiment (variant) is used to manufacture a battery pack.

[0479] FIG. 25 is a diagram schematically illustrating the configuration of a battery pack according to one embodiment of the present invention.

[0480] 25, a battery pack 300 according to an embodiment of the present invention includes an assembly of electrically connected cylindrical batteries 301 and a pack housing 302 that accommodates the assembly. The cylindrical batteries 301 may be any one of the batteries according to the above-described embodiments (variants). For convenience of illustration, components such as bus bars for electrical connection of the cylindrical batteries 301, a cooling unit, and external terminals are not shown.

[0481] The battery pack 300 is mounted on a vehicle. The vehicle may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The vehicle may be a four-wheeled vehicle or a two-wheeled vehicle.

[0482] FIG. 26 is a diagram illustrating a vehicle including the battery pack 300 of FIG.

[0483] 26, an automobile V according to an embodiment of the present invention includes a battery pack 300 according to an embodiment of the present invention. The automobile V operates by receiving a supply of power from the battery pack 300 according to an embodiment of the present invention.

[0484] According to an embodiment of the present invention, the uncoated portions protruding from the upper and lower sides of the electrode assembly are used as electrode tabs, thereby reducing the internal resistance of the battery and increasing the energy density.

[0485] Furthermore, according to one embodiment of the present invention, the structure of the uncoated portion of the electrode assembly is improved so that the electrode assembly does not interfere with the inner surface of the battery housing during the process of forming the beading portion of the battery housing, thereby preventing internal short circuits in cylindrical batteries due to partial deformation of the electrode assembly.

[0486] Furthermore, according to one embodiment of the present invention, the structure of the uncoated portion of the electrode assembly is improved to prevent the uncoated portion from being torn when the uncoated portion is bent, and the number of overlapping layers of the uncoated portion is sufficiently increased to improve the welding strength of the current collector.

[0487] In addition, according to one embodiment of the present invention, a plurality of segments are formed in the uncoated portion of the electrode, and when the electrode is wound up, the plurality of segments are aligned in a predetermined direction. In areas where no segments are arranged, the ends of the active material layer formed on the electrode are exposed between the wound turns of the separator, thereby increasing the electrolyte impregnation (speed and uniformity).

[0488] In addition, according to one embodiment of the present invention, by applying a segment structure to the uncoated portion of the electrode and optimizing the dimensions (width, height, and spacing pitch) of the segments, the number of segments stacked in the area used as the welding target area can be sufficiently increased, thereby improving the physical properties of the area where the current collector plate is welded.

[0489] In addition, the present invention can provide an electrode assembly in which cutting grooves are repeatedly formed in the uncoated portion of the electrode along the winding direction to form a multi-segment structure, and the lower structure of the cutting grooves is optimized to improve the notching quality of the cutting grooves.

[0490] Furthermore, according to one embodiment of the present invention, a structure in which a current collector plate is welded over a wide area to a folded surface region formed by bending a segmented piece is applied, thereby providing an electrode assembly with improved energy density and reduced resistance.

[0491] Furthermore, according to one embodiment of the present invention, a cylindrical battery with an improved design that allows electrical wiring to be performed at the top can be provided.

[0492] Furthermore, according to one embodiment of the present invention, the structure of the uncoated portion adjacent to the core of the electrode assembly is improved to prevent the cavity in the core of the electrode assembly from being blocked when the uncoated portion is bent, facilitating the electrolyte injection process and the welding process between the battery housing (or rivet terminal) and the current collector plate.

[0493] Furthermore, according to one embodiment of the present invention, it is possible to provide a cylindrical battery having a structure in which internal resistance is low, internal short circuits are prevented, and welding strength between a current collector plate and a non-coating portion is improved, as well as a battery pack and a vehicle including the same.

[0494] 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 same, and a vehicle.

[0495] As described above, the present invention has been described using limited embodiments and drawings, but the present invention is not limited thereto, and it goes without saying that various modifications and variations can be made by a person having ordinary knowledge in the technical field to which the present invention pertains within the technical spirit of the present invention and the equivalent scope of the claims. [Explanation of symbols]

[0496] 41 Current collector 42 Active material layer 43 Plain area 43a First plain section 43b 2nd plain area 44 insulating coating layer 60 electrodes 61-minute sections 63 Cutting groove 63a Side 63b Round section 65 Electrode assembly 66 Independent area 70 electrodes 80 Electrode assembly 100 electrode assembly 110 Electrode assembly 120 Electrode assembly 130 Electrode assembly 140 Battery 141 Electrode assembly 142 Battery Housing 143 Sealed body 144 First current collector plate 145 Second current collector plate 146 Insulators 146a First plain section 146b Second plain section 147 Beading section 148 Crimping section 149 leads 150 width contrast 151 Lead hole 152 Venting section 171 Battery housing 171a flat plane 172 Rivet terminal 172a Exposed terminal part 172b Terminal insertion part 172c flat area 173 Second gasket 173a Exposed gasket 173b Gasket insert 174 Insulators 176 Second current collector plate 178 Sealed body 179 Vent 180 Beading section 181 Crimping section 190 Cylindrical Battery 200 Cylindrical Battery 210 Busbar 211 Body 212 First bus bar terminal 213 Second bus bar terminal 220 Cylindrical Battery 300 battery pack 301 Cylindrical Battery 302 Pack Housing

Claims

1. 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 a winding direction, and a first uncoated portion not coated with an active material layer, the first plain portion includes a plurality of segments that can be bent independently, a cut groove formed by discontinuously irradiating a laser is interposed between adjacent cut pieces in the winding direction, The lower part of the cutting groove is composed of a rounded portion that does not include a straight section, the plurality of segments are folded along a radial direction to form a folded surface region; The folded surface region has a region where segments located on different winding turns are stacked in 10 or more layers in the winding axis direction.

2. The electrode assembly according to claim 1 , wherein the rounded portion has a shape substantially the same as a circle whose diameter is equal to the spacing pitch between adjacent segment pieces in the winding direction.

3. The electrode assembly according to claim 1 , wherein the rounded portion has a shape that approximately follows a circle whose diameter is equal to the spacing pitch between adjacent segment pieces in the winding direction.

4. The rounded portion connects the side portions of the cut pieces located on both sides of the cutting groove, 4. The electrode assembly according to claim 1, wherein the radius of curvature of the rounded portion gradually increases and then gradually decreases from a side of one side segment to a side of the other side segment in a section corresponding to a separation pitch between adjacent segment segments in the winding direction.

5. 4. The electrode assembly according to claim 2, wherein the spacing pitch is 0.05 mm to 2.0 mm.

6. 4. The electrode assembly according to claim 2, wherein the spacing pitch is 0.5 mm to 1.0 mm.

7. The electrode assembly according to claim 1 , wherein the side portions of the divided pieces located on both sides of the cutting groove extend linearly and are connected to both ends of the rounded portion.

8. The upper portion of the segment extends linearly along the winding direction, The side portions of the cut pieces located on both sides of the cutting groove extend linearly, The electrode assembly according to claim 1 , wherein an upper corner of the segment where the upper portion and the side portion intersect has a rounded shape.

9. 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 and second electrodes around a winding shaft, the first electrode including a first active material portion coated with an active material layer along the winding direction and a first uncoated portion not coated with the active material layer, the first uncoated portion including a plurality of segments that can be bent independently, cut grooves formed by discontinuous laser irradiation are interposed between adjacent segments in the winding direction, and lower portions of the cut grooves are formed by rounded portions that do not include straight sections, the plurality of segments are bent along a radial direction to form a folded surface region, and the folded surface region has a region in which the segments located at different winding turns are overlapped in 10 or more layers along the winding shaft; a battery housing including an open end and a bottom portion opposite the open end, the battery housing accommodating the electrode assembly in a space between the open end and the bottom portion, the battery housing being electrically connected to one of the first electrode and the second electrode and having a first polarity; a seal that seals the open end of the battery housing; a current collecting plate welded to the region overlapped by 10 or more layers; a terminal of a second polarity coupled to the current collector plate and electrically connected to the other of the first electrode and the second electrode, the terminal having an exposed surface to the outside.

10. The battery according to claim 9 , wherein the rounded portion has a shape substantially the same as a circle whose diameter is equal to the spacing pitch between adjacent segment pieces in the winding direction.

11. The battery according to claim 9 , wherein the rounded portion has a shape that approximately follows a circle whose diameter is equal to the spacing pitch between adjacent segment pieces in the winding direction.

12. The rounded portion connects the side portions of the cut pieces located on both sides of the cutting groove, 12. The battery according to claim 9, wherein the radius of curvature of the rounded portion gradually increases and then gradually decreases from a side of one side segment to a side of the other side segment in a section corresponding to a separation pitch between adjacent segment segments in the winding direction.

13. The electrode assembly has a core provided with a cavity, 12. The battery according to claim 9, wherein the cavity is not blocked by the folded surface region and is open to the outside.

14. the sealing body includes a cap plate that seals the open end of the battery housing, and a gasket that encloses the periphery of the cap plate and is crimped to the open end of the battery housing, 12. The battery of claim 9, wherein the terminal having the second polarity is the cap plate.

15. An electrode assembly in which a core and an outer peripheral surface are defined by winding a first electrode, a second electrode, and a separation membrane interposed between the first and second electrodes 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, the first plain portion including a plurality of segments that can be bent independently, cutting grooves with rounded portions at the bottom interposed between adjacent segments in the winding direction, and the plurality of segments being bent along the radial direction to form a bent surface region; a battery housing including an open end and a bottom portion opposite the open end, the battery housing accommodating the electrode assembly in a space between the open end and the bottom portion, the battery housing being electrically connected to one of the first electrode and the second electrode and having a first polarity; a seal that seals the open end of the battery housing; a terminal of a second polarity electrically connected to the other of the first electrode and the second electrode and having a surface exposed to the outside, further comprising a current collector electrically connected to an uncoated portion of the second electrode having the first polarity and having at least a portion of its periphery joined to a side wall of the battery housing; the sealing body includes a non-polarized cap plate and a gasket that encloses the periphery of the cap plate and is crimped to the open end of the battery housing; The battery housing includes a rivet terminal insulatively attached to a through hole formed in the center of the bottom, electrically connected to the first electrode, and having the second polarity.

16. A battery pack comprising a plurality of batteries according to any one of claims 9 to 11 and 15.

17. 17. A motor vehicle including the battery pack of claim 16.

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