Electrode assembly and cylindrical secondary battery provided with same

Abstract

In relation to a tabless secondary battery to which a cylindrical electrode assembly using an end of an electrode sheet, which is not coated with an active material, as an electrode tab is applied, the present invention provides an electrode assembly structure capable of preventing the risk of short-circuiting in a core section of the electrode assembly and additionally securing a current path in the core section to reduce the amount of heat generated due to internal resistance, and a cylindrical secondary battery to which the electrode assembly is applied. The core section of the electrode sheet is provided with a plateau which protrudes outward in the axial direction beyond a cutting groove defining a division tab and extends in the longitudinal direction. The division tab is bent inward in the radial direction. While in the unbent state, the upper end of the plateau contacts and is electrically connected to the division tab.

Description

Electrode assembly and cylindrical secondary battery having the same

[0001] This application claims the benefit of priority from Republic of Korea Patent Application No. 10-2023-0197349, dated December 29, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to an electrode assembly and a cylindrical secondary battery having the same, and more particularly, to a tab-less secondary battery using a cylindrical electrode assembly that uses an end of an electrode sheet that is not coated with an active material as an electrode tab, wherein the electrode assembly structure is capable of preventing a short circuit from occurring in a core section of the electrode assembly and reducing the amount of heat generated due to internal resistance by additionally securing a current path in the core section, and a cylindrical secondary battery using the electrode assembly.

[0003] Secondary batteries are used in a wide range of fields. Their scope of application has expanded significantly, from portable devices to energy storage media for vehicle operation.

[0004] Compared to pouch-type battery cells, cylindrical can-type battery cells are considered safer due to their metal housings. Recently, as cylindrical battery cell specifications have expanded, to increase energy density, areas of the electrode sheet that are not coated with active material are formed instead of tabs, and these areas are used as electrode tabs.

[0005] In particular, by bending the flag-shaped electrode tabs provided at the ends of the electrode assembly radially and overlapping them, the current path is dispersed, which has the advantage of lowering the internal resistance even in high-capacity battery cells.

[0006] However, since these battery cells do not form electrode tabs in the core section, the current path is not distributed to the core section, and thus the current path is not completely distributed. In particular, when using a battery cell with a small diameter, the ratio of the core section to the overall diameter of the electrode assembly is large, so the degree to which the current path is not distributed is further increased.

[0007] Meanwhile, in order to prevent the core cavity of the electrode assembly from being covered by the electrode tab during the assembly process of the battery cell, no electrode tab is provided in the core section of the electrode assembly.

[0008] If the electrode tab located radially outside the axial end of the electrode assembly where the electrode tab is not provided is bent and laid down, there is a risk that the bent electrode tab portion may come into contact with another electrode sheet inside the electrode assembly, causing a short circuit.

[0009] The present invention has been devised to solve the above-described problems, and aims to provide an electrode assembly structure that can minimize the amount of heat generated by internal resistance during a charge / discharge process by providing a path through which current can flow directly in a core section of an electrode assembly, thereby lowering internal resistance, and can prevent an electrode tab bent into a core section from causing a short circuit with another electrode inside the electrode assembly, and a cylindrical secondary battery using the same.

[0010] The technical objectives of the present invention are not limited to the purposes mentioned above. Other objectives and advantages of the present invention not mentioned above can be understood through the following description and will be more clearly understood through the embodiments of the present invention. Furthermore, it will be readily apparent that the objectives and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims.

[0011] The present invention can be applied to an electrode assembly in which an electrode sheet and a separator are laminated and then rolled into a jelly-roll shape. The jelly-roll can be rolled into a cylindrical shape.

[0012] The above electrode sheet can be extended in the longitudinal direction with a predetermined width. The winding axis can correspond to the width of the electrode sheet.

[0013] A non-coated portion not coated with an active material may be provided on one side of the width direction of the above electrode sheet.

[0014] In the above-mentioned blank portion, a first cutting groove extending axially outward at a plurality of locations spaced apart in the longitudinal direction can be provided, and the blank portion can be divided by the first cutting groove to form a plurality of split tabs.

[0015] The above-mentioned split tab may extend axially outward from the first valley, which is the lower portion of the first incision groove, and may have a predetermined height. The height of the split tab may be equal to or greater than the minimum height at which the split tab can be smoothly bent.

[0016] The above-mentioned portion has a main section in which the split tab is formed in the longitudinal direction, and a core section extending longitudinally inward from the core-side end of the main section to the core-side end of the electrode sheet.

[0017] A plurality of the above split tabs are provided in the main section. In other words, the above split tabs are not provided in the core section.

[0018] In the above core section, a plateau is provided that protrudes axially outward by a first height from the first valley of the first cut groove and extends in the longitudinal direction.

[0019] A plurality of the above split tabs are bent at a predetermined position at the lower end such that the upper ends of the split tabs face radially toward the core side of the jelly-roll.

[0020] The upper portion of the above plateau is electrically connected to the inner surface of the first split tab, which is arranged adjacent to the radially outer side of the above plateau and is bent.

[0021] The above plateau can be extended axially outward to contact the inner surface of the first split tab.

[0022] The first height of the above plateau is lower than the height of the first split tab.

[0023] The above first height can be determined at a level that can secure strength that prevents axial buckling.

[0024] The above first height may be 0.5 mm or more and 1.5 mm or less.

[0025] The height of the above first split tab may be 3 mm or more.

[0026] The upper end of the above plateau may be positioned axially further outward than the axial end of the above membrane.

[0027] The above first valley may be located axially further outward than the axial end of the membrane.

[0028] The above plateau may be provided with a plurality of elastic protrusions divided by second cut grooves extending axially outward at a plurality of locations spaced apart in the longitudinal direction.

[0029] The upper part of the above elastic protrusion can be in contact with the inner surface of the first split tab and be electrically connected.

[0030] The above plurality of elastic protrusions are elastically deformed to be curved radially inward and can be electrically connected to the inner surface of the split tab.

[0031] The above second valley may be located further outward in the axial direction than the above first valley.

[0032] The second height from the second valley of the second incision groove to the axial outer end of the elastic protrusion may be smaller than the first height.

[0033] The above second height may be 0.5 mm or more and 1.0 mm or less.

[0034] The difference between the first height and the second height may be 0.5 mm or more and 1.0 mm or less.

[0035] The above second valley may be located axially further outward than the axial end of the above membrane.

[0036] The above electrode assembly may further include a current collector plate that is axially facing and electrically connected to the outer surfaces of the plurality of split tabs by welding.

[0037] The present invention provides a battery cell that houses the electrode assembly in a can and closes the open end of the can with a cap.

[0038] In one example, the outer surfaces of the plurality of split tabs may be welded to the bottom member of the can.

[0039] In one example, the outer surfaces of the plurality of split tabs may be welded to the cap.

[0040] In one example, the central portion of the collector plate may be welded to the bottom member of the can, so that the split tab may be electrically connected to the bottom member of the can.

[0041] In one example, the central portion of the current collector plate is insulated and sealed to the central portion of the bottom member of the can and welded to the installed electrode terminal, so that the split tab can be electrically connected to the electrode terminal.

[0042] In one example, the collector plate may be bonded to the cap or can such that the split tab is electrically connected to the cap or can.

[0043] According to the present invention, a plateau having a height small enough to prevent buckling is formed in the core section of the electrode assembly, and the upper end of the plateau supports and contacts a split tab bent radially inward, thereby securing a current path to the core section, while preventing the split tab from digging into the separator, thereby preventing a phenomenon in which a short circuit occurs between different electrodes.

[0044] According to the present invention, by providing a small elastic protrusion on the upper part of the plateau, a larger contact area with the split tab can be secured, and the elastic protrusion can be deformed to further increase the buckling resistance of the plateau.

[0045] According to the present invention, a path through which current can flow directly to the core section is provided, thereby reducing internal resistance and minimizing the amount of heat generated by internal resistance during the charging and discharging process.

[0046] In addition to the effects described above, specific effects of the present invention are described below while explaining specific details for carrying out the invention.

[0047] Figure 1 is an expanded view of the first electrode sheet of the electrode assembly of the embodiment.

[0048] Figure 2 is an enlarged view of the core section of Figure 1.

[0049] Figure 3 is an enlarged view of the core section of the first electrode sheet of another embodiment.

[0050] Figure 4 is a development diagram of a state in which a first electrode sheet, a second electrode sheet, and a separator are laminated.

[0051] Fig. 5 is an enlarged view of the core section of the electrode laminate of Fig. 4.

[0052] Fig. 6 is a side view of the electrode stack of Fig. 4 viewed in the longitudinal direction.

[0053] Fig. 7 is a side view showing only the first electrode sheet near the core portion in a rolled state of an electrode laminate to which the first electrode sheet of Fig. 2 is applied.

[0054] Fig. 8 is a side view of the split tab of the first electrode sheet of Fig. 7 bent radially inward.

[0055] Fig. 9 is a side view showing only the first electrode sheet near the core portion in a rolled state of an electrode laminate to which the first electrode sheet of Fig. 3 is applied.

[0056] Fig. 10 is a side view of the split tab of the first electrode sheet of Fig. 9 bent radially inward.

[0057] Figure 11 is a perspective view of an electrode assembly showing a state in which the split tab is bent radially inward.

[0058] Fig. 12 is a perspective view showing a state in which a current collector plate is laminated on the axial end of the electrode assembly of Fig. 11 and joined to a split tab.

[0059] Figure 13 is a cross-sectional view showing a state in which the split tab of an electrode assembly without stacking the current collector plates is joined by contacting the bottom of the can.

[0060] Figure 14 is a cross-sectional view showing a state in which the current collector plates of an electrode assembly having stacked current collector plates are joined by contacting the bottom of the can.

[0061] Figure 15 is a cross-sectional view showing a state in which the current collector plate of an electrode assembly in which current collector plates are laminated is electrically connected by bonding it to a cap assembly.

[0062] Figure 16 is a cross-sectional view showing a state in which a current collector plate of an electrode assembly having a stack of current collector plates is connected to an electrode terminal provided on the bottom of a can.

[0063] Figure 17 is a cross-sectional view showing a state in which the current collector plates of an electrode assembly in which current collector plates are laminated are electrically connected by bonding them to a can.

[0064] Figure 18 is a cross-sectional view showing a state in which the split tab of an electrode assembly without stacking the current collector plates is joined by contacting the cap.

[0065] [Explanation of symbols]

[0066] 10: Electrode sheet, first electrode sheet 11: Active material 12: Non-conductive part C: Core section 13: Plateau h1: First height 131: Elastic protrusion 137: Second cut groove 139: Second valley h2: Second height M: Main section 15: Split tab, first split tab 157: First cut groove 158: First valley H: Height O: Outer circumference section 20: Second electrode sheet 30: Separator 40: Electrode assembly 50: Collector plate 60: Can 61: Bottom member 62: Electrode terminal 63: Terminal gasket 64: Insulator 65: Side wall member 66: Beading part 67: Crimping part 70: Cap 71: Cap gasket W: Joint part

[0067] The above-described objects, features, and advantages will be described in detail below with reference to the accompanying drawings, so that those skilled in the art can easily practice the technical idea of ​​the present invention. In describing the present invention, if it is determined that a detailed description of known technologies related to the present invention may unnecessarily obscure the gist of the present invention, a detailed description thereof will be omitted. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

[0068] Although terms like "first" and "second" are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless otherwise specified, a "first" component may also be a "second" component.

[0069] Throughout the specification, unless otherwise specifically stated, each element may be singular or plural.

[0070] Hereinafter, the phrase "any configuration is placed on (or below)" a component or "on (or below)" a component may mean that any configuration is placed in contact with the upper surface (or lower surface) of said component, and that other configurations may be interposed between said component and any configuration placed on (or below) said component.

[0071] Additionally, when it is described that a component is "connected," "coupled," or "connected" to another component, it should be understood that the components may be directly connected or connected to one another, but that other components may also be "interposed" between the components, or that each component may be "connected," "coupled," or "connected" through another component.

[0072] As used herein, singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, terms such as "consisting of" or "comprising" should not necessarily be construed to include all of the components or steps described in the specification, and should be construed to mean that some of the components or steps may not be included, or that additional components or steps may be included.

[0073] Throughout the specification, when we refer to "A and / or B", this means A, B, or A and B, unless otherwise stated, and when we refer to "C through D", this means C or more and D or less, unless otherwise stated.

[0074] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[0075] For convenience of explanation, in describing the embodiments, the direction of the long side of the electrode sheet is referred to as the longitudinal direction, and the direction of the short side is referred to as the width direction. When such an electrode sheet is rolled into a cylindrical shape, the longitudinal direction of the electrode sheet matches the circumferential direction or the periphery direction of the electrode assembly, and the width direction of the electrode sheet matches the axial direction of the electrode assembly. In addition, the front and back sides of the electrode sheet in the unfolded state match the inner and outer surfaces in the rolled state. The direction toward or away from the central axis of the electrode assembly is referred to as the radial direction. If the center of the electrode assembly is referred to as the core, and the outer periphery of the electrode assembly is referred to as the outer periphery, the radially inner and outer sides of the rolled electrode sheet can be referred to as the core side and the outer periphery side of the electrode sheet in the unfolded state, respectively.

[0076] Referring to FIGS. 1 to 12, the electrode assembly (40) of the embodiment can be manufactured in a cylindrical jelly-roll shape by sequentially stacking a first electrode sheet (10), a separator (30), a second electrode sheet (20), and a separator (30), and winding the first electrode sheet (10) around a core axis extending in a direction corresponding to the width direction of the electrode sheet.

[0077] The first electrode sheet (10) and the second electrode sheet (20) may have different polarities. For example, if the first electrode sheet (10) is an anode as in the embodiment, the second electrode sheet (20) may be a cathode. Since the structure of the second electrode sheet (20) corresponds to that of the first electrode sheet (10), the first electrode sheet (10) will be described below.

[0078] The above first electrode sheet (10) can be extended in the longitudinal direction with a predetermined width.

[0079] An active material (11) is coated on one or both sides of the first electrode sheet (10). A non-coated portion (12) not coated with the active material (11) may be provided on the upper portion of the first electrode sheet (10).

[0080] In the above-mentioned portion, a first cutting groove (157) extending axially outward is provided at a plurality of locations spaced apart in the longitudinal direction. The first cutting groove (157) can be formed by cutting with, for example, a knife or laser.

[0081] The above-mentioned non-woven part (12) can form a plurality of split tabs (15) that are split lengthwise by the first cutting groove (157).

[0082] The above split tab (15) may extend axially outward from the first valley (158), which is the lower portion of the first cut groove (157), and may have a predetermined height. The height of the split tab (15) may be equal to or greater than the minimum height at which the split tab (15) can be smoothly bent.

[0083] The height of the above-mentioned split tab (15) may have a shape in which the height gradually increases from the core side to the outer periphery side. This may increase gradually or stepwise. Of course, the height distribution of the split tab (15) is not limited to this. In addition, although the embodiment exemplifies that the shape of the split tab (15) is an equilateral trapezoid, the shape need not necessarily be limited to this. For example, the split tab may be configured in various shapes such as a trapezoid, a triangle, a parallelogram, or a semicircle.

[0084] The above-mentioned non-conductive section (12) can be divided into a main section (M) in which the split tab (15) is formed in the longitudinal direction, a core section (C) arranged closer to the core than the main section (M), and an outer section (O) arranged closer to the outer periphery than the main section (M).

[0085] A plurality of the above split tabs (15) are provided in the main section (M). No split tabs (15) are provided in the outer peripheral section (O) and core section (C).

[0086] The above outer circumferential section (O) may have a length approximately equal to the last turn of the electrode assembly (40). If a split tab (15) exists in the last turn of the electrode assembly (40), there is a risk that the outer circumferential split tab (15) may be deformed during the process of handling the electrode assembly (40) to assemble a battery cell. However, if the outer circumferential section (O) is provided as described above, this risk can be eliminated. The above outer circumferential section (O) may be omitted as needed.

[0087] Referring to Fig. 2, in the core section (C), a plateau is provided that protrudes axially outward by a first height (h1) from the first valley (158) of the first cut groove (157) and extends in the longitudinal direction. The first height (h1) can be determined at a level that can secure strength that prevents axial buckling of the plateau (13) during the bending and contact process of the split tab (15) described later.

[0088] The plurality of split tabs (15) are bent at a predetermined position at the lower end thereof so that the upper ends of the split tabs (15) face radially inward. Accordingly, the upper end of the plateau (13) is in contact with the inner circumferential surface (inner surface) of the bent split tabs and is electrically connected thereto.

[0089] If the split tab arranged adjacent to the core section (C) is called the first split tab (15), the upper part of the plateau (13) is in direct contact with the inner surface of the first split tab (15) and is electrically connected thereto.

[0090] For this purpose, the first height (h1) of the above plateau (13) is set lower than the height (H) of the first split tab (15).

[0091] In order to contact the inner surface of the first split tab (15), the plateau (13) can be maintained in a state of extending axially outward as shown in Fig. 8. In order to prevent buckling of the plateau (13), the first height (h1) of the plateau (13) can be set in a range of 0.5 mm or more and 1.5 mm or less.

[0092] The height (H) of the first split tab (15) may be about 3 mm or more so that the bending can be performed smoothly.

[0093] The upper end of the above plateau (13) is positioned axially further outward than the axial end of the separator (30). Accordingly, even if the plateau (13) buckles, the phenomenon of the separator (30) being deformed due to the buckling of the plateau (13) can be minimized.

[0094] The above first valley (158) is located axially further outward than the axial end of the separator (30). Accordingly, when bending the split tab (15), the phenomenon of the bent portion of the split tab (15) deforming the separator (30) can be prevented.

[0095] Referring to Fig. 3, the upper portion of the plateau (13) is divided by a second cutting groove (137) extending axially outward at a plurality of locations spaced apart in the longitudinal direction. Accordingly, an elastic protrusion (131) that is relatively more easily elastically deformed than the plateau (13) is provided between two adjacent second cutting grooves (137). As illustrated in Fig. 10, the upper portion of the elastic protrusion (131) is elastically deformed to be curved radially inward and can be in contact with and electrically connected to the inner surface of the first split tab (15).

[0096] The second valley (139) is located axially further outward than the axial end of the membrane (30). The second valley (139) is located axially further outward than the first valley (158).

[0097] The second height (h2) from the second valley (139) of the second incision groove (137) to the axial outer end of the elastic protrusion (131) may be smaller than the first height (h1).

[0098] The above second height (h2) may be 0.5 mm or more and 1.0 mm or less.

[0099] The difference between the first height (h1) and the second height (h2) may be 0.5 mm or more and 1.0 mm or less.

[0100] The above elastic protrusion (131) has second cutting grooves (137) on both sides, so that it can be deformed with relatively weak rigidity. When the above elastic protrusion (131) is elastically deformed and extends in the radial direction, not only does the contact area with the split tab (15) increase, but the buckling stability of the plateau (13) can also increase.

[0101] By winding the electrode assembly (40) in this way and bending the split tab (15), the axial end of the electrode assembly (40) can provide a flat surface as shown in FIG. 11.

[0102] Then, as illustrated in Fig. 12, a current collector plate can be laminated on the axial end of the electrode assembly, and the current collector plate (50) can be bonded to the bent portion of the flattened split tab (15). The bonding can be accomplished by a welding method that irradiates a laser to the outer surface of the current collector plate (50). Of course, the bonding or welding method is not limited thereto.

[0103] The above split tab (15) may be provided on only one end of the electrode assembly (40) or on both ends. The embodiment exemplifies an electrode assembly (40) in which split tabs (15) are formed on both ends.

[0104] Referring to FIGS. 13 to 18 below, a method for implementing cylindrical battery cells of various structures by applying the above-described electrode assembly (40) is described.

[0105] The above battery cell is manufactured by accommodating the electrode assembly (40) in a can (60) and covering the open end of the can (60) with a cap (70).

[0106] The above electrode assembly (40) can be connected to the electrode terminal of the can using a current collector plate (50), or can be directly connected to the electrode terminal using a split tab (15) without a current collector plate (50).

[0107] For example, referring to FIG. 13, the split tab (15) provided at the end of the electrode assembly (40) can be directly brought into contact with and bonded to the bottom member (61) of the can (60) without the current collector plate (50). The bonding can be performed by irradiating a laser from the outside of the bottom member (61) of the can (60) to the surface of the bottom member (61) of the can (60) and welding. Of course, the bonding or welding method is not limited thereto.

[0108] As another example, referring to FIG. 14, the central portion of the current collector (50) provided at the end of the electrode assembly (40) can be directly contacted and joined to the bottom member (61) of the can (60). As the joining method, a resistance welding method may be applied, in which a first resistance electrode is contacted to the outer central portion of the bottom member (61) of the can (60), a second resistance electrode is contacted to the inner surface of the central portion of the current collector (50) through the core cavity of the electrode assembly (40), and a high current is passed through it to weld, or an ultrasonic welding method may be applied. In the resistance welding method, a donut-shaped insulator (64) may be interposed between the current collector (50) and the bottom member (61) in order to prevent current dispersion. Of course, the joining or welding method is not limited thereto.

[0109] Next, referring to FIG. 15, the current collector plate (50) can be electrically connected to a cap (70) that covers and closes the open end of the side wall member (65) of the can (60). For example, in a state where the current collector plate (50) is first bonded to the cap (70), the open end of the side wall member (65) can be covered with the cap (70) and the crimping portion (67) can be formed. The cap (70) can be pressed by the beading portion (66) and the crimping portion (67) in a state where the edge thereof interposes the cap gasket (71).

[0110] Next, referring to FIG. 16, the central portion of the current collector plate (50) of the electrode assembly (40) can be joined to the electrode terminal (62) fixed to the central portion of the bottom member (61) of the can (60) with the terminal gasket (63) interposed therebetween. At this time, an insulator (64) can be interposed between the current collector plate (50) and the bottom member (61) of the can (60) to prevent short circuit.

[0111] Next, referring to FIG. 17, the current collector (50) extends to the compression portion of the can (60) and the cap (70), and is joined to the upper portion of the beading portion (66) of the can (60) at that portion, thereby being electrically connected to the can (60). Referring to FIG. 17, the cap (70) may be insulated from the can (60) by the cap gasket (71) and may not be electrically conductive.

[0112] Next, referring to FIG. 18, the split tab (15) of the electrode assembly (40) can be directly bonded to and electrically connected to a cap (70) that covers and closes the open end of the can (60). This bonding can be achieved by irradiating a laser onto the surface of the cap (70). In addition, the edge of the cap (70) can be fixed and electrically connected to the edge of the side wall member (65) of the can (60) by welding or the like.

[0113] It should be understood that the above-described embodiments are illustrative in all respects and not restrictive, and the scope of the present invention will be determined by the claims that follow, rather than by the detailed description set forth above. Furthermore, the meaning and scope of the claims that follow, as well as all possible modifications and variations derived from their equivalent concepts, should be construed as encompassing the scope of the present invention.

[0114] Although the present invention has been described with reference to the drawings exemplified above, it is to be understood that the present invention is not limited to the embodiments and drawings disclosed herein, and that various modifications may be made by those skilled in the art within the scope of the technical idea of ​​the present invention. Furthermore, even if the operational effects according to the configuration of the present invention have not been explicitly described while describing the embodiments of the present invention, it is natural that the effects predictable by the corresponding configuration should also be acknowledged.

Claims

1. A jelly-roll-shaped electrode sheet having a predetermined width and extending in the longitudinal direction, a non-coated portion on one side in the width direction that is not coated with an active material, and wound around a winding axis parallel to the width direction; and In an electrode assembly including a plurality of split tabs, wherein the non-conductive portion is divided by a first cutting groove extending axially outward at a plurality of locations spaced apart in the longitudinal direction; The above-mentioned portion has, in the longitudinal direction, a main section, and a core section extending from the core-side end of the main section to the core-side end of the electrode sheet in the longitudinal direction inward, A plurality of the above split tabs are provided in the above main section, In the above core section, a plateau is provided that protrudes axially outward by a first height from the first valley of the first cut groove that defines the above split tab and extends in the longitudinal direction. A plurality of said split tabs are bent at a predetermined position at the lower end so that the upper ends of said split tabs face radially toward the core side of said jelly-roll, An electrode assembly in which the upper part of the above plateau is electrically connected to the inner surface of a first split tab that is arranged adjacent to the radially outer side of the above plateau and is bent.

2. An electrode assembly according to claim 1, wherein the plateau extends axially outward.

3. An electrode assembly according to claim 1, wherein the first height of the plateau is lower than the height of the first split tab.

4. In claim 1, the electrode sheet is laminated and wound on a separator, An electrode assembly, wherein the upper portion of the above plateau is positioned axially further outside than the axial end of the separator.

5. In claim 1, the electrode sheet is laminated and wound on a separator, An electrode assembly, wherein the first valley is located axially further outside the axial end of the separator.

6. An electrode assembly according to claim 1, wherein the first height is 0.5 mm or more and 1.5 mm or less.

7. In claim 1, the plateau is provided with a plurality of elastic protrusions divided by second cutting grooves extending axially outward at a plurality of locations spaced apart in the longitudinal direction, An electrode assembly in which the upper portions of the plurality of elastic protrusions are in contact with and electrically connected to the inner surface of the first split tab.

8. An electrode assembly according to claim 7, wherein the plurality of elastic protrusions are bent radially inwardly and electrically connected to the inner surface of the split tab.

9. An electrode assembly according to claim 7, wherein the second valley is positioned further outward in the axial direction than the first valley.

10. An electrode assembly according to claim 7, wherein the second height from the second valley of the second cut groove to the axial outer end of the elastic protrusion is smaller than the first height.

11. In claim 10, the electrode sheet is laminated and wound on a separator, An electrode assembly, wherein the second valley is located axially further outside the axial end of the separator.

12. An electrode assembly according to claim 10, wherein the second height is 0.5 mm or more and 1.0 mm or less.

13. An electrode assembly according to claim 7, wherein the difference between the first height and the second height is 0.5 mm or more and 1.0 mm or less.

14. An electrode assembly according to any one of claims 1 to 13, wherein a plurality of current collector plates are welded and electrically connected to each other while facing each other in the axial direction on the outer surfaces of the split tabs.

15. An electrode assembly according to any one of claims 1 to 13; A can accommodating the above electrode assembly; and A cap for closing and closing the open end of the can; A battery cell, wherein the outer surfaces of a plurality of said split tabs are welded to the bottom member of the can.

16. An electrode assembly according to any one of claims 1 to 13; A can accommodating the above electrode assembly; and A cap for closing and closing the open end of the can; A battery cell, wherein the outer surfaces of a plurality of said split tabs are welded to the cap.

17. Electrode assembly of claim 14; A can accommodating the above electrode assembly; and A cap for closing and closing the open end of the can; A battery cell, wherein the central portion of the above current collector plate is welded to the bottom member of the can.

18. Electrode assembly of claim 14; A can accommodating the above electrode assembly; and A cap for closing and closing the open end of the can; A battery cell in which the central portion of the above current collector plate is insulated and sealed and welded to an electrode terminal installed in the central portion of the bottom member of the can.

19. Electrode assembly of claim 14; A can accommodating the above electrode assembly; and A cap for closing and closing the open end of the can; A battery cell, wherein said collector plate is electrically connected to said can or cap.

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