Method for winding electrode assembly, electrode assembly wound thereby, and battery cell containing same

Abstract

Provided are: a method for winding an electrode assembly, whereby a jelly-roll may be rapidly discharged to the outside of a can when a thermal runaway occurs, thereby preventing a side rupture phenomenon of the can; an electrode assembly wound thereby; and a battery cell containing same. Outer circumferential portion winding tensions for a separator and an electrode are greater than middle portion winding tensions for the separator and the electrode, respectively, and the middle portion winding tensions for the separator and the electrode are greater than core portion winding tensions for the separator and the electrode, respectively. In the outer circumferential portion section of winding, the separator is wound with an outer circumferential portion winding tension that is greater than the winding tensions for all sections for the electrode. In the middle portion section of winding, the separator is wound with a middle portion winding tension that is greater than the core portion winding tension for the electrode. The electrode and the separator are wound, in the core portion, the middle portion, and the outer circumferential portion sections of winding, respectively, with 300 g.f. and 250 g.f., respectively, 500 g.f. and 400 g.f., respectively, and 700 g.f. and 900 g.f., respectively.

Description

Method for winding an electrode assembly, an electrode assembly wound by the method, and a battery cell including the same

[0001] This application claims the benefit of priority from Republic of Korea Patent Application No. 10-2024-0100536, dated July 29, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a method for winding an electrode assembly, and more particularly, to a method for winding an electrode assembly capable of preventing a side rupture of a can by rapidly discharging a jelly-roll outside the can when thermal runaway occurs, an electrode assembly wound by this method, and a battery cell including the same.

[0003] With the recent surge in demand for secondary batteries, various forms of secondary batteries are being developed. Cylindrical battery cells, which house a jelly-roll-shaped electrode assembly within a cylindrical metal can, are more shock- and temperature-resistant than pouch-type batteries. Consequently, demand for can-shaped cells for use in vehicle battery packs is growing.

[0004] Conventional can-shaped battery cells electrically connect the electrodes and the can or terminals by bonding a separate tab member to the current collector of the electrode assembly and bonding the tab member to the can or terminal. However, in battery cells with this structure, the structure for electrically connecting the electrodes and terminals takes up a significant amount of internal space within the can. Furthermore, this electrical connection structure has limitations in reducing internal resistance because the current path is limited to the tab member. An electrical connection structure that makes it difficult to reduce internal resistance is unsuitable for application to large-capacity battery cells that carry high currents.

[0005] Recently, cylindrical battery cells have been developed with increasing volume to increase energy capacity. Furthermore, technological development is being focused on maximizing the internal space of cylindrical battery cells, maximizing the volume of the electrode assembly housed within the internal space.

[0006] Accordingly, a structure has recently been developed in which a non-coated portion of the current collector is exposed to the axial end of the electrode assembly, folded in a radial direction so that the folded non-coated portion forms a flat surface facing the axial direction, a current collector plate is welded to the surface, and the current collector plate is again joined to a can or a rivet terminal. According to this structure, the current path between the electrode and the can or terminal is widened to lower the internal resistance, while the space inside the can occupied by the electrical connection structure between the electrode and the can or terminal is minimized, thereby further increasing the energy density of the battery cell.

[0007] In addition, in a battery cell of this structure, the rivet terminal provided at the axial first end of the can and the end wall of the can can constitute a first electrode terminal and a second electrode terminal, respectively, so that all bus bars electrically connected to the battery cell can be placed on the upper part of the battery cell.

[0008] However, high-energy density, high-capacity battery cells generate significant heat and pressure when exposed to harsh environments, such as high temperatures or overcharge or rapid charge / discharge cycles, leading to thermal runaway. This increases the risk of lateral bursting, potentially damaging the sides or beading of the can, rather than the designed vent structure.

[0009] If a lateral burst occurs during a thermal runaway event, the flames will escape in a direction other than the vent structure, directly contacting other battery cells within the battery module or battery pack adjacent to the battery cell undergoing thermal runaway. This can cause a chain reaction of thermal runaway events.

[0010] That is, in order to improve the safety of battery modules and battery packs, there is a high need to prevent lateral bursting when thermal runaway occurs in battery cells.

[0011] The present invention has been devised to solve the above-described problems, and aims to provide a battery cell that can prevent lateral bursting of a can even when thermal runaway occurs.

[0012] The present invention aims to provide a battery cell capable of smoothly discharging heat and pressure through a designed vent structure during thermal runaway.

[0013] The present invention aims to provide an electrode assembly that can be quickly discharged outside a can during thermal runaway.

[0014] 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.

[0015] In order to solve the above-described problem, the present invention controls the winding tension of an electrode assembly wound in a jelly-roll shape so that the electrode assembly is quickly discharged to the outside through Ken's vent structure in a thermal runaway situation of a battery cell.

[0016] The above electrode assembly is assembled in a jelly-roll shape by winding the first electrode and the second electrode with the separator interposed therebetween around a core.

[0017] The above electrode assembly can be accommodated inside the can through an opening provided at the axial first end of the can.

[0018] The opening of the above can can be sealed with a cap.

[0019] In a partial example, the axial first end of the can is radially inwardly recessed to form a beading portion, the opening of the can is covered with the cap, the edge of the cap is placed on the beading portion, and the axial first end of the can is bent radially inwardly to form a crimping portion, thereby allowing the edge of the cap to be pressed axially between the beading portion and the crimping portion of the can.

[0020] In a partial example, the edge of the cap may be joined to the axial first end of the can by welding or the like.

[0021] The above electrode assembly can be wound around a core by winding a first electrode and a second electrode together, with a first separator and a second separator interposed between the first electrode and the second electrode.

[0022] The above electrode assembly is wound with a predetermined tension in each of the core section, middle section, and outer circumference section of the winding.

[0023] The above electrode assembly can be wound with different tensions in the core section, middle section, and outer circumference section of the winding.

[0024] The above electrode assembly is manufactured by winding the electrode and the separator while applying a predetermined winding tension to each of them.

[0025] In the above electrode assembly, the winding tensions applied to the electrode and the separator may be different from each other.

[0026] In the above electrode assembly, the electrode and the separator are each wound with a predetermined core winding tension in the core section, the electrode and the separator are each wound with a predetermined middle winding tension in the middle section, and the electrode and the separator are each wound with a predetermined outer winding tension in the outer peripheral section.

[0027] The above electrode assembly is wound so that the intermediate winding tension applied to the electrode in the middle section of the winding is greater than the core winding tension applied to the electrode in the core section of the winding, and so that the outer circumference winding tension applied to the electrode in the outer circumference section of the winding is greater than the intermediate winding tension applied to the electrode in the middle section of the winding.

[0028] The above electrode assembly is wound so that the intermediate winding tension applied to the separator in the middle section of the winding is greater than the core winding tension applied to the separator in the core section of the winding, and so that the outer circumferential winding tension applied to the separator in the outer circumferential section of the winding is greater than the intermediate winding tension applied to the separator in the middle section of the winding.

[0029] The above electrode assembly winds the separator in the outer peripheral section of the winding with an outer peripheral winding tension that is equal to or greater than the maximum winding tension of the entire section for the electrode.

[0030] Preferably, the electrode assembly can be wound with an outer circumferential winding tension greater than the winding tension of the entire section of the electrode, in the outer circumferential section of the winding.

[0031] The above electrode assembly can be wound with a middle section winding tension that is not less than the core section winding tension for the electrode, in the middle section of the winding.

[0032] Preferably, the electrode assembly can be wound with a middle section winding tension greater than the core section winding tension for the electrode, in the middle section of the winding.

[0033] The above electrode assembly can be wound with an intermediate winding tension greater than the winding tension of the core section and the intermediate section for the separator in the intermediate section of the winding.

[0034] The above electrode assembly can be wound with an outer circumferential winding tension greater than the winding tension of the core section and the middle section for the separator in the outer circumferential section of the winding.

[0035] The above electrode can be wound with a winding tension of 250 g.f. (gram force) or more and 550 g.f. or less in the core section of the winding, with a winding tension of 450 g.f. or more and 750 g.f. or less in the middle section of the winding, and with a winding tension of 650 g.f. or more and 950 g.f. or less in the outer peripheral section of the winding.

[0036] Preferably, the electrode can be wound with a winding tension of 250 g.f. or more and 450 g.f. or less in the core section of the winding, with a winding tension of 450 g.f. or more and 650 g.f. or less in the middle section of the winding, and with a winding tension of 650 g.f. or more and 850 g.f. or less in the outer peripheral section of the winding.

[0037] More preferably, the electrode can be wound with a winding tension of 250 g.f. or more and 350 g.f. or less in the core section of the winding, with a winding tension of 450 g.f. or more and 550 g.f. or less in the middle section of the winding, and with a winding tension of 650 g.f. or more and 750 g.f. or less in the outer peripheral section of the winding.

[0038] The above separator can be wound with a winding tension of 200 g.f. or more and 300 g.f. or less in the core section of the winding, with a winding tension of 300 g.f. or more and 500 g.f. or less in the middle section of the winding, and with a winding tension of 700 g.f. or more and 1100 g.f. or less in the outer peripheral section of the winding.

[0039] Preferably, the separator can be wound with a winding tension of 200 g.f. or more and 300 g.f. or less in the core section of the winding, with a winding tension of 350 g.f. or more and 450 g.f. or less in the middle section of the winding, and with a winding tension of 800 g.f. or more and 1000 g.f. or less in the outer peripheral section of the winding.

[0040] More preferably, the separator can be wound with a winding tension of 200 g.f. or more and 300 g.f. or less in the core section of the winding, with a winding tension of 350 g.f. or more and 450 g.f. or less in the middle section of the winding, and with a winding tension of 850 g.f. or more and 950 g.f. or less in the outer peripheral section of the winding.

[0041] An electrode assembly manufactured by a winding method according to the present invention has an outer circumferential winding tension for the electrode that is greater than the middle winding tension for the electrode, and the middle winding tension for the electrode is greater than the core winding tension for the electrode.

[0042] The above electrode assembly has an outer circumferential winding tension for the separator greater than an intermediate winding tension for the separator, and the intermediate winding tension for the separator is greater than an inner core winding tension for the separator.

[0043] The electrode assembly has a winding tension of the entire section for the electrode that is equal to or less than the winding tension of the outer circumference for the separator. Preferably, the winding tension of the entire section for the electrode is less than the winding tension of the outer circumference for the separator.

[0044] The above electrode assembly may have a core portion winding tension for the electrode that is equal to or less than a middle portion winding tension for the separator. Preferably, the core portion winding tension for the electrode may be less than the middle portion winding tension for the separator.

[0045] The above electrode assembly may have a core portion winding tension for the electrode that is greater than a core portion winding tension for the separator.

[0046] The electrode assembly may have a middle winding tension for the electrode that is greater than the core winding tension and middle winding tension for the separator. The electrode assembly may have an outer peripheral winding tension for the electrode that is greater than the core winding tension and middle winding tension for the separator.

[0047] The core winding tension of the electrode of the above electrode assembly may be 250 g.f. or more and 550 g.f. or less, the middle winding tension may be 450 g.f. or more and 750 g.f. or less, and the outer peripheral winding tension may be 650 g.f. or more and 950 g.f. or less.

[0048] Preferably, the core winding tension for the electrode of the electrode assembly may be 250 g.f. or more and 450 g.f. or less, 450 g.f. or more and 650 g.f. or less, and 650 g.f. or more and 850 g.f. or less.

[0049] More preferably, the core winding tension of the electrode of the electrode assembly may be 250 g.f. or more and 350 g.f. or less, the middle winding tension may be 450 g.f. or more and 550 g.f. or less, and the outer peripheral winding tension may be 650 g.f. or more and 750 g.f. or less.

[0050] The core winding tension of the separator of the electrode assembly may be 200 g.f. or more and 300 g.f. or less, the middle winding tension may be 300 g.f. or more and 500 g.f. or less, and the outer circumference winding tension may be 700 g.f. or more and 1100 g.f. or less. Preferably, the middle winding tension may be 350 g.f. or more and 450 g.f. or less, and the outer circumference winding tension may be 800 g.f. or more and 1000 g.f. or less. More preferably, the outer circumference winding tension may be 850 g.f. or more and 900 g.f. or less.

[0051] A battery cell including an electrode assembly according to the present invention includes a can that accommodates the electrode assembly therein through an opening provided at an axial first end, and a cap having an edge fixed to the can and covering and sealing the opening.

[0052] In a partial example, the can may have a beading portion formed by radially inwardly recessing a first axial end of the can, and a crimping portion formed by radially bending the first axial end of the can. The edge of the cap may be axially pressed between the beading portion and the crimping portion of the can.

[0053] In a partial example, the edge of the cap may be joined and fixed to the axial first end of the can by welding or the like.

[0054] An electrode assembly assembled by a winding method according to the present invention has an outer circumferential winding tension for a separator that is greater than the core and middle winding tensions for a separator and greater than the entire winding tension for an electrode, so that the outer shape of the electrode assembly is reliably maintained, and axial discharge of the core and middle portions of the electrode assembly can be smoothly achieved in a thermal runaway situation.

[0055] The electrode assembly assembled by the winding method according to the present invention has a core portion winding tension for the electrode and a core portion winding tension for the separator that are both smaller than the middle portion winding tension for the separator, so that the timing of the discharge behavior of the core portion of the electrode assembly is accelerated in a thermal runaway situation. Accordingly, the timing of the jelly-roll discharge can be advanced in a thermal runaway situation, allowing venting to occur before the internal temperature and pressure of the can rise significantly.

[0056] The electrode assembly assembled by the winding method according to the present invention has a core portion winding tension relative to the separator that is smaller than the core portion winding tension relative to the electrode, so that the timing of the discharge behavior of the core portion of the electrode assembly is accelerated in a thermal runaway situation. Accordingly, the timing of the jelly-roll discharge can be advanced in a thermal runaway situation, thereby allowing venting to occur before the internal temperature and pressure of the can rise significantly.

[0057] An electrode assembly assembled by a winding method according to the present invention has a middle section winding tension for the electrode that is greater than the core section winding tension and middle section winding tension for the separator, so that in a thermal runaway situation, the middle section of the electrode assembly can be smoothly discharged following the core section.

[0058] A battery cell comprising an electrode assembly assembled using the winding method of the present invention can prevent rapid increases in internal temperature and pressure within the can, as the electrode assembly is discharged smoothly in a thermal runaway situation. This prevents damage to the side wall of the can.

[0059] A battery module or battery pack including a battery cell having an electrode assembly assembled by a winding method according to the present invention can prevent thermal runaway from propagating and expanding to battery cells around the battery cell in which thermal runaway has occurred, since venting occurs in a designed direction without lateral damage to the can even if thermal runaway occurs in a specific battery cell.

[0060] 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.

[0061] Figure 1 is an exploded perspective view of an electrode assembly wound using a winding method according to an embodiment of the present invention.

[0062] Figure 2 is a plan view schematically illustrating the winding process of the electrode assembly.

[0063] Figure 3 is a perspective view of an electrode assembly according to an embodiment of the present invention.

[0064] Figure 4 is a perspective view of a battery cell with the electrode assembly of Figure 3 built into a can.

[0065] Figure 5 is a cross-sectional view of the battery cell of Figure 4.

[0066] Figure 6 shows a form in which the electrode assembly of the battery cell of Figure 5 is discharged in a thermal runaway situation.

[0067] Figure 7 is a cross-sectional view and an enlarged view of an electrode assembly of an embodiment.

[0068] Figure 8 is a perspective view showing the process of attaching a weight to the axial end of the electrode assembly being tested.

[0069] Figures 9 and 10 are side views and cross-sectional views showing a state in which a weight is attached to the axial end of the electrode assembly being tested.

[0070] Figure 11 is a cross-sectional perspective view of the tester's guide duct and striker.

[0071] Fig. 12 is a cross-sectional view of the guide duct and striker of Fig. 11.

[0072] Fig. 13 is a cross-sectional view showing a state in which an electrode assembly with a weight attached is placed at the drop start position of the guide duct of Fig. 12.

[0073] Figure 14 is a cross-sectional view showing a state in which the electrode assembly of Figure 13 is dropped and the striker begins to impact the core portion of the electrode assembly.

[0074] Figures 15 and 16 are X-ray photographs of the raised portion of the core of an electrode assembly after testing electrode assemblies wound with different winding tensions.

[0075] [Explanation of symbols]

[0076] 10: Can (housing) 11: Side wall 12: End wall (second electrode terminal) 13: Beading part 14: Crimping part 15: Rivet terminal (electrode terminal) 16: Terminal gasket 19: Insulator 20: Electrode assembly 21: First electrode 22: Second electrode 23: Current collector 24: Active material 25: Holding part 26: Non-conductive part 27: Electrode tab (notching tab) 28: Separator SS: Slitting surface 30: First current collector 40: Second current collector 50: Cap 51: Vent notch 55: Gasket 61: Weight 62: Attachment tape 65: Guide duct 66: Striker 70: Winding core S1: Core section S2: Middle section S3: Outer circumference section Te: Electrode winding tension Ts: Separator Winding tension

[0077] 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 a detailed description of a known technology related to the present invention is judged to 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.

[0078] 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.

[0079] Throughout the specification, unless otherwise specifically stated, each element may be singular or plural.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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 to D", this means C or more and D or less, unless otherwise stated.

[0084] In describing the embodiments, the axial direction may refer to the direction in which the axis forming the winding center of the jelly-roll type electrode assembly, i.e., the winding axis, extends. This may be understood as a concept including both directions in which the axis extends. In describing the embodiments, the radial direction or radial direction refers to a direction approaching or away from the axis. This may be understood as a concept including both directions approaching or away from the axis. In describing the embodiments, the circumferential direction or circumferential direction refers to a direction surrounding the axis.

[0085] Based on the definition of these directions, the width direction of the electrode assembly in the unfolded state corresponds to the axial direction of the jelly roll. The length direction of the electrode assembly in the unfolded state corresponds to the circumferential direction of the jelly roll. And the normal direction to the electrode surface in the unfolded state of the electrode assembly corresponds to the radial direction of the jelly roll.

[0086] Referring to FIGS. 1 to 5 below, the assembly process and structure of a cylindrical battery cell having an electrode assembly to which a winding method according to an embodiment of the present invention is applied will be described.

[0087] The battery cell of the embodiment may be, for example, a cylindrical battery cell having a form factor ratio (defined as the ratio of the diameter of the cylindrical battery cell divided by its height, i.e., the ratio of the diameter to the height) of greater than about 0.4.

[0088] Here, the form factor refers to a value indicating the diameter and height of a cylindrical battery cell. The cylindrical battery cell may be, for example, a 46110 cell, a 48750 cell, a 48110 cell, a 48800 cell, a 46800 cell, or a 46950 cell. In the numerical value indicating the form factor, the first two numbers indicate the diameter of the cell, the next two numbers indicate the height of the cell, and the last number 0 indicates that the cross-section of the cell is circular.

[0089] The above battery cell may be a cylindrical battery cell having a roughly cylindrical shape, a diameter of approximately 46 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0090] A battery cell according to another embodiment may be a cylindrical battery cell having a generally cylindrical shape, a diameter of approximately 48 mm, a height of approximately 75 mm, and a form factor ratio of 0.640.

[0091] According to another embodiment, a battery cell may be a cylindrical battery cell having a generally cylindrical shape, a diameter of approximately 48 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0092] According to another embodiment, a battery cell may be a cylindrical battery cell having a generally cylindrical shape, a diameter of approximately 48 mm, a height of approximately 80 mm, and a form factor ratio of 0.600.

[0093] According to another embodiment, a battery cell may be a cylindrical battery cell having a generally cylindrical shape, a diameter of approximately 46 mm, a height of approximately 80 mm, and a form factor ratio of 0.575.

[0094] The present invention can of course also be applied to battery cells having a form factor ratio of approximately 0.4 or less, such as 18650 cells, 21700 cells, etc. For 18650 cells, the diameter is approximately 18 mm, the height is approximately 65 mm, and the form factor ratio is 0.277. For 21700 cells, the diameter is approximately 21 mm, the height is approximately 70 mm, and the form factor ratio is 0.300.

[0095] Referring to FIGS. 4 and 5, the battery cell of the embodiment includes a housing (10) having a side wall (11) extending in the axial direction, an end wall (12) connected to an axial first end of the side wall (11), and an open end or opening provided at an axial second end of the side wall (11). The housing (10) may be a can (10) made of metal.

[0096] The above battery cell has a jelly-roll shaped electrode assembly (20) accommodated in the can (10).

[0097] The electrode assembly (20) is manufactured by preparing a first electrode (21), a second electrode (22), and a separator (28) having a predetermined width and extending in the longitudinal direction as shown in FIG. 1, and forming a laminate by stacking the first electrode (21), the separator (28), the second electrode (22), and the separator (28) in that order as shown in FIG. 2, and winding this around a core (70) to form a jelly-roll shape as shown in FIG. 3.

[0098] The above first electrode (21) may be an anode, and the above second electrode (22) may be a cathode. Of course, the opposite may also be the case.

[0099] The first electrode (21) and the second electrode (22) are manufactured in the form of a roll sheet that extends in the length direction with a predetermined width. The electrodes (21, 22) are manufactured in the form of forming an active material layer by applying an active material (24) to the surface of a metal foil constituting a current collector (23) and rolling it. The electrodes (21, 22) have a holding portion (25) region where the active material (24) is applied, and a non-coated portion (26) region where the active material (24) is not applied. The first electrode (21) has a non-coated portion (26) region at a first end of the current collector (23) in the width direction, and the second electrode (22) has a non-coated portion (26) region at a second end of the current collector (23) opposite the first end in the width direction.

[0100] The first electrode (21) and the second electrode (22) are laminated so that their uncoated portions (26) extend further outward in the width direction than the separator (28) at the first and second ends in the width direction of the electrode assembly (20), respectively. Accordingly, the uncoated portion (26) of the first electrode (21) protrudes from the axial first end of the rolled jelly-roll, and the uncoated portion (26) of the second electrode (21) protrudes from the axial second end of the jelly-roll. The uncoated portion (26) itself functions as at least one electrode tab (27).

[0101] In the above-mentioned blank portion (26), notches can be formed at a predetermined interval to form flag-shaped notching tabs (27).

[0102] In the embodiment, the above-described notching tabs (27) are implemented in the shape of an equilateral trapezoid. However, their shapes may be various shapes such as a semicircle, a semi-ellipse, a triangle, a rectangle, a parallelogram, etc.

[0103] In addition, in the embodiment, the notching tabs (27) arranged along the longitudinal direction are implemented to have the same width. However, the width of the notching tabs may be gradually or stepwise widened from the core side to the outer periphery side.

[0104] In addition, in the embodiment, the height of the notching tabs (27) is implemented to gradually increase from the core side to the outer circumference side as illustrated in Fig. 1. However, differently from this, the height of these notching tabs may be implemented to be constant or to gradually decrease.

[0105] In addition, in the embodiment, a structure is implemented in which a notching tab (27) is deleted in a predetermined section of the core side end of the above-mentioned plain portion (26) and a predetermined section of the outer side end. However, it goes without saying that, unlike this, the notching tab may not be deleted in the core side end of the plain portion, the notching tab may not be deleted in the outer side end of the plain portion, or the notching tab may not be deleted in both sides.

[0106] In the jelly-roll type electrode assembly (20), the notched tab (27) can be folded and flattened radially as shown in FIG. 3. The notched tab (27) can be folded radially inward or outward. In the embodiment, the notched tab (27) is implemented in a structure in which it is folded radially inward.

[0107] The above-mentioned notched tabs (27) may be pre-bent one by one during the process of forming a jelly-roll-shaped electrode assembly (20) by stacking and winding electrodes and separators, and then may be finally bent again after being wound in a jelly-roll shape. Alternatively, the above-mentioned notched tabs (27) may be bent all at once after stacking and winding electrodes and separators to form a jelly-roll-shaped electrode assembly.

[0108] The notching tabs (27) of the first electrode (21) and the notching tabs (27) of the second electrode (22), which are bent in the radial direction and overlapped in multiple numbers in the axial direction, can provide a plane that is substantially perpendicular to the axial direction at the axially opposite ends of the electrode assembly (20).

[0109] A first collector plate (30) and a second collector plate (40) can be joined to a substantially flat surface provided by bending the notched tabs (27) exposed at the first and second axial ends of the electrode assembly (20), respectively. The first collector plate (30) is joined at a peripheral portion to the notched tab (27) of the first electrode (21) of the electrode assembly (20) by welding or the like, and a first portion of the second collector plate (40) is joined to the notched tab (27) of the second electrode (22) of the electrode assembly (20) by welding or the like (see FIG. 5).

[0110] The above current collector plates (30, 40) can be manufactured by punching, trimming, piercing, or bending a metal sheet or metal plate. In an embodiment, the first current collector plate (30) is implemented as a positive current collector plate and the second current collector plate (40) is implemented as a negative current collector plate. The first current collector plate (30) may be made of aluminum and the second current collector plate (40) may be made of copper. However, alternatively, the first current collector plate (30) may be a negative current collector plate made of copper, and the second current collector plate (40) may be a positive current collector plate made of aluminum.

[0111] Referring to Fig. 5, the end wall (12) of the can (10) may have a disc shape with a through hole formed in the center, and the side wall (11) may have a circular tube shape surrounding the internal volume of the can (10).

[0112] An electrode terminal (15) is fitted into the above through hole. The electrode terminal (15) can be fixed to the end wall (12) with a terminal gasket (16) interposed therebetween. The terminal gasket (16) is interposed between the electrode terminal (15) and the end wall (12), sealing the inside and outside of the can (10) to prevent leakage of the electrolyte and electrically insulating the electrode terminal (15) from the end wall (12).

[0113] The electrode assembly (20) in which the collector plates (30, 40) are assembled is accommodated inside the can (10) through an opening provided at the axial second end of the can (10). The electrode assembly (20) is accommodated in the can (10) in a state in which the first collector plate (30) is aligned so as to face the end wall (12) of the can (10). Before inserting the electrode assembly (20) into the can (10), an insulator (19) may be laminated on the inner surface of the end wall (12). The insulator (19) interposed between the first collector plate (30) and the end wall (12) of the can (10) electrically insulates the first collector plate (30) from the end wall (12).

[0114] After the above electrode assembly (20) is accommodated in the can (10), the central portion of the first current collector (30) is joined to the electrode terminal (15) by resistance welding, ultrasonic welding, laser welding, or other methods. Accordingly, the first electrode (21) of the electrode assembly (20) and the electrode terminal (15) are electrically connected.

[0115] The welding device for welding the first collector plate (30) and the electrode terminal (15) can approach the back surface (surface facing the electrode assembly (20)) of the central portion (33) of the first collector plate (30) through the core hollow portion of the electrode assembly (20) from the open end of the can (10) to perform welding. Of course, in addition to this, the first collector plate (30) and the electrode terminal (15) can also be joined by brazing or soldering. In other words, various methods can be applied to the first collector plate (30) and the electrode terminal (15) as long as they are a joining method that can electrically connect them and fix them to each other.

[0116] With the electrode assembly (20) accommodated inside the can (10), the electrode tab (27) of the second electrode (22) is positioned to face the open end of the side wall (11), i.e., the opening of the housing (10). After the electrode assembly (20) is accommodated in the can (10), the second portion of the second current collector (30) is joined to the beading portion (13) of the can (10) by welding or the like. Accordingly, the second electrode (22) of the electrode assembly (20) and the can (10) are electrically connected.

[0117] When the first collector plate (30) and the second collector plate (40) are respectively connected to the electrode terminal (15) and the can (10), the electrode terminal (15) can have a first polarity, and the can (10) can have a second polarity. That is, the end wall (12) of the can (10) and the side wall (11) connected thereto can both have a second polarity.

[0118] Accordingly, the battery cell may have both the first electrode terminal (15) and the second electrode terminal (12) positioned at the axial end, i.e., the closed end, provided with the end wall (12). Then, the battery cell may have both the first bus bar connected to the first electrode terminal (15) and the second bus bar connected to the end wall (12) electrically connected to the second electrode (22) positioned at one axial side (upper) of the battery cell.

[0119] In one embodiment, the first electrode terminal (15) may be a positive terminal and the second electrode terminal may be a negative terminal. Of course, the opposite may also be true.

[0120] After the first collector plate (30) and the second collector plate (40) are respectively joined to the electrode terminal (15) and the can (10), the edge of the cap (50) covering the opening of the can (10) is placed on the beading portion (13), and a crimping portion (14) is formed to press the edge of the cap (50). The edge of the cap (50) is pressed with the gasket (55) interposed therebetween, and the can (10) is thereby sealed.

[0121] Referring to Fig. 6, the cap (50) is provided with a vent notch (51) that can be broken by the internal pressure of the can (10). When a short circuit occurs in the battery cell or a thermal runaway situation occurs due to factors such as overcharging or high temperature, the internal temperature and pressure of the can (10) rapidly increase, the vent notch (51) is broken, and the cap (50) is opened. Then, the electrode assembly (20) and gas are discharged in the axial direction through the broken cap (50). In this process of discharging the electrode assembly (20) and gas, the jelly-roll of the electrode assembly (20) is ejected in a form that rises from the core portion, as illustrated in Fig. 6 (b).

[0122] As illustrated in FIG. 2, when the electrode assembly (20) is wound, the electrodes (21, 22) and the separator (28, 28) constituting the electrode assembly (20) are each wound with tension (T) applied. Since the electrodes (21, 22) use a metal foil as a substrate, while the separator (28) uses a polymer resin material as a substrate, they complement each other in maintaining the jelly-roll construction state after being wound with tension applied. According to an embodiment, the winding tension (Te) for the electrodes (21, 22) and the winding tension (Ts) for the separator (28) are set differently, as needed.

[0123] In addition, according to the embodiment, the electrode assembly (20) is wound with different tensions in the core section (S1), the middle section (S2), and the outer circumference section (S3) of the winding, as illustrated in FIG. 7. The present invention controls the winding tensions (T) of the core section (S1), the middle section (S2), and the outer circumference section (S3) for the electrodes (21, 22) and the separator (28), respectively, so that the jelly-roll is quickly discharged into the vent path of the can (10) in a thermal runaway situation.

[0124] According to an embodiment, the electrode assembly (20) is such that the electrodes (21, 22) and the separator (28) are each wound with a predetermined core winding tension (T1) in the core section (S1), the electrodes (21, 22) and the separator (28) are each wound with a predetermined middle winding tension (T2) in the middle section (S2), and the electrodes (21, 22) and the separator (28) are each wound with a predetermined outer winding tension (T3) in the outer peripheral section (S3).

[0125] Specifically, the electrode assembly (20) is wound so that the intermediate winding tension (Te2) applied to the electrodes (21, 22) in the intermediate section (S2) of the winding is greater than the core winding tension (Te1) applied to the electrodes (21, 22) in the core section (S1) of the winding, and the outer circumferential winding tension (Te3) applied to the electrodes (21, 22) in the outer circumferential section (S3) of the winding is greater than the intermediate winding tension (Te2) applied to the electrodes (21, 22) in the intermediate section (S2) of the winding.

[0126] And the above electrode assembly (20) is wound so that the intermediate winding tension (Ts2) applied to the separator (28) in the intermediate section (S2) of the winding is greater than the core winding tension (Ts1) applied to the separator (28) in the core section (S1) of the winding, and the outer circumferential winding tension (Ts3) applied to the separator (28) in the outer circumferential section (S3) of the winding is greater than the intermediate winding tension (Ts2) applied to the separator (28) in the intermediate section (S2) of the winding.

[0127] The electrode assembly (20) winds the separator (28) in the outer circumferential section (S3) of the winding with an outer circumferential winding tension (Ts3) that is equal to or greater than the maximum winding tension (Te) of the entire sections (S1, S2, S3) for the electrodes (21, 22). Preferably, the electrode assembly (20) winds the separator (28) in the outer circumferential section (S3) of the winding with an outer circumferential winding tension (Ts3) that is greater than the winding tension (Te) of the entire sections (S1, S2, S3) for the electrodes (21, 22).

[0128] In addition, the electrode assembly (20) winds the separator (28) in the middle section (S2) of the winding with a middle section winding tension (Ts2) that is not less than the core section winding tension (Te1) for the electrodes (21, 22). Preferably, the electrode assembly (20) winds the separator (28) in the middle section (S2) of the winding with a middle section winding tension (Ts2) that is greater than the core section winding tension (Te1) for the electrodes (21, 22).

[0129] Additionally, the electrode assembly (20) winds the electrodes (21, 22) in the middle section (S2) of the winding with a middle section winding tension (Te2) that is greater than the winding tensions (Ts1, Ts2) of the core section (S1) and the middle section (S2) for the separator (28). And, in the outer section (S3) of the winding, the electrodes (21, 22) are wound with a outer section winding tension (Te3) that is greater than the winding tensions (Ts1, Ts2) of the core section (S1) and the middle section (S2) for the separator (28).

[0130] The above electrodes (21, 22) are wound with a winding tension (Te1) of 250 g.f. or more and 550 g.f. or less in the core section (S1) of the winding, with a winding tension (Te2) of 450 g.f. or more and 750 g.f. or less in the middle section (S2) of the winding, and with a winding tension (Te3) of 650 g.f. or more and 950 g.f. or less in the outer peripheral section (S3) of the winding.

[0131] Preferably, the electrodes (21, 22) are wound with a winding tension (Te1) of 250 g.f. or more and 450 g.f. or less in the core section (S1) of the winding, with a winding tension (Te2) of 450 g.f. or more and 650 g.f. or less in the middle section (S2) of the winding, and with a winding tension (Te3) of 650 g.f. or more and 850 g.f. or less in the outer peripheral section (S3) of the winding.

[0132] More preferably, the electrodes (21, 22) are wound with a winding tension (Te1) of 250 g.f. or more and 350 g.f. or less in the core section (S1) of the winding, with a winding tension (Te2) of 450 g.f. or more and 550 g.f. or less in the middle section (S2) of the winding, and with a winding tension (Te3) of 650 g.f. or more and 750 g.f. or less in the outer peripheral section (S3) of the winding.

[0133] The above separator (28) is wound with a winding tension (Ts1) of 200 g.f. or more and 300 g.f. or less in the core section (S1) of the winding, with a winding tension (Ts2) of 300 g.f. or more and 500 g.f. or less in the middle section (S2) of the winding, and with a winding tension (Ts3) of 700 g.f. or more and 1100 g.f. or less in the outer peripheral section (S3) of the winding.

[0134] Preferably, the separator (28) is wound with a winding tension (Ts1) of 200 g.f. or more and 300 g.f. or less in the core section (S1) of the winding, with a winding tension (Ts2) of 350 g.f. or more and 450 g.f. or less in the middle section (S2) of the winding, and with a winding tension (Ts3) of 800 g.f. or more and 1000 g.f. or less in the outer peripheral section (S3) of the winding.

[0135] More preferably, the separator (28) is wound with a winding tension (Ts1) of 200 g.f. or more and 300 g.f. or less in the core section (S1) of the winding, with a winding tension (Ts2) of 350 g.f. or more and 450 g.f. or less in the middle section (S2) of the winding, and with a winding tension (Ts3) of 850 g.f. or more and 950 g.f. or less in the outer peripheral section (S3) of the winding.

[0136] The electrode assembly (20) manufactured by the above-described winding method has an outer circumferential winding tension (Te3) for the electrodes (21, 22) that is greater than the middle winding tension (Te2) for the electrodes (21, 22), and the middle winding tension (Te2) for the electrodes (21, 22) is greater than the core winding tension (Te1) for the electrodes (21, 22). In addition, the outer circumferential winding tension (Ts3) for the separator (28) is greater than the middle winding tension (Ts2) for the separator (28), and the middle winding tension (Ts2) for the separator (28) is greater than the core winding tension (Ts1) for the separator (28).

[0137] The above electrode assembly (20) has a winding tension (Te) of the entire section (S1, S2, S3) for the electrodes (21, 22) that is equal to or less than the outer circumferential winding tension (Ts3) for the separator (28). Preferably, the winding tension (Te) of the entire section (S1, S2, S3) for the electrodes (21, 22) is less than the outer circumferential winding tension (Ts3) for the separator (28).

[0138] The electrode assembly (20) above has an outer circumferential winding tension (Ts3) for the separator (28) that is greater than the core winding tension (Ts1) and the middle winding tension (Ts2) for the separator (28) and is greater than the winding tension (Te) of the entire sections (S1, S2, S3) for the electrodes (21, 22), so that the outer shape of the electrode assembly (20) is maintained reliably, and axial discharge of the core section (S1) and the middle section (S2) of the electrode assembly (20) is smoothly performed in a thermal runaway situation.

[0139] The electrode assembly (20) has a core winding tension (Te1) for the electrodes (21, 22) that is equal to or less than the middle winding tension (Ts2) for the separator (28). Preferably, the core winding tension (Te1) for the electrodes (21, 22) is less than the middle winding tension (Ts2) for the separator (28).

[0140] In the above electrode assembly (20), since the core section winding tension (Te1) for the electrodes (21, 22) and the core section winding tension (Ts1) for the separator (28) are both smaller than the middle section winding tension (Ts2) for the separator (28), the timing of the discharge behavior of the core section (S1) of the electrode assembly (20) is accelerated in a thermal runaway situation. Accordingly, the timing of the jelly-roll discharge can be advanced in a thermal runaway situation, so that venting is performed before the internal temperature and pressure of the can (10) rise significantly.

[0141] The electrode assembly (20) has a core part winding tension (Te1) for the electrodes (21, 22) that is greater than the core part winding tension (Ts1) for the separator (28). That is, the electrode assembly (20) has a core part winding tension (Ts1) for the separator (28) that is smaller than the core part winding tension (Te1) for the electrodes (21, 22). Therefore, the timing of the discharge behavior of the core part section (S1) of the electrode assembly (20) is accelerated in a thermal runaway situation. Accordingly, the timing of the jelly-roll discharge can be advanced in a thermal runaway situation, so that venting is performed before the internal temperature and pressure of the can (10) rise significantly.

[0142] The electrode assembly (20) has a middle section winding tension (Te2) for the electrodes (21, 22) that is greater than the core section winding tension (Ts1) and middle section winding tension (Ts2) for the separator (28). That is, since the electrode assembly (20) has a middle section winding tension (Te2) for the electrodes (21, 22) that is greater than the core section winding tension (Ts1) and middle section winding tension (Ts2) for the separator (28), the discharge of the middle section (S2) of the electrode assembly (20) is smoothly performed following the core section (S1) in a thermal runaway situation.

[0143] The above electrode assembly (20) has an outer circumferential winding tension (Te3) for the electrodes (21, 22) greater than the core winding tension (Ts1) and the middle winding tension (Ts2) for the separator (28).

[0144] Referring to FIGS. 7 to 16, a predetermined test method is proposed to determine the relationship between the winding tension of an electrode assembly and the ease of rising of a jelly-roll. According to a tester used in the test method, a predetermined axial impact is applied around the core hollow portion of the core section (S1) of the axial first end of the electrode assembly (20) having a predetermined diameter (Di). Then, based on the rising information related to the shape of the first electrode (21) rising axially outwardly at the axial second end of the electrode assembly (20), the rate of change of the rising information according to the change in the winding tension (T) is examined, and the influence of the winding tension (T) on the thermal runaway behavior of the electrode assembly is evaluated.

[0145] The above tester is equipped with a weight (61), an attachment tape (62), a guide duct (65), and a striker (66).

[0146] A weight (61) is attached to the axial second end of the electrode assembly (20). At the axial second end of the electrode assembly (20), the non-conductive portion (26) of the second electrode (22) protrudes axially outward and is bent radially inward. In addition, the axial second end of the electrode assembly (20) has a slitting surface (SS) of the first electrode (21). The slitting surface (SS) is positioned axially inward relative to the separator (28).

[0147] Referring to FIGS. 8 to 10, the weight (61) is a metal ring having an inner diameter (Da) larger than the inner diameter (Di) of the hollow portion of the electrode assembly (20) and an outer diameter (Db) corresponding to the outer diameter (Do) of the electrode assembly (20). Accordingly, when the core section (S1) of the electrode assembly (20) rises in an impact test, it does not interfere with the weight (61). As illustrated in FIG. 9, an attachment tape (62) is wrapped around the outer circumference of the weight (61) and the outer circumference of the electrode assembly (20), and the weight (61) is attached and fixed to the axial second end of the electrode assembly (20).

[0148] Referring to FIGS. 11 to 14, the electrode assembly (20) is dropped onto the striker (66) in a posture in which the weight (61) is placed at the top. The guide duct (65) guides the electrode assembly (20) to drop accurately toward the striker (66) while maintaining the posture so that the core portion of the axial first end of the electrode assembly (20) is accurately struck by the striker (66).

[0149] The above guide duct (65) has a tubular shape with a bore of circular cross-section. The inner diameter of the guide duct (65) is set to be slightly larger than the outer diameter of the electrode assembly (20) and / or the weight (61), and the length (L) of the guide duct (65) is set so that a predetermined amount of impact can be applied to the electrode assembly (20) in consideration of the mass of the electrode assembly (20) and the weight (61).

[0150] A striker (66) is arranged at the center of the lower portion of the guide duct (65). The striker (66) may have a cylindrical shape with an outer diameter slightly larger than the inner diameter (Di) of the hollow portion of the electrode assembly (20). The outer diameter (D) of the striker (66) may be 1.03 to 1.05 times larger than the inner diameter (Di) of the electrode assembly (20) to be tested. This is the most advantageous ratio for identifying the phenomenon in which loosening begins by concentrating the impact on the inner circumference of the electrode assembly (20) where the tension is released. This is determined at a level that can strike about 1 to 3 turns of the innermost circumference, taking into account the thickness of the laminate of the rolled positive electrode, separator, negative electrode, and separator. Taking into account the deviation of the inner diameter (Di) of the electrode assembly (20), etc., the striker (66) is implemented so that the diameter of the striker (66) decreases as it goes upward in the axial direction. The diameter of the striker (66) is determined based on the inner diameter of the electrode assembly (20) to be tested and the thickness of the winding turn.

[0151] When the electrode assembly (20) is dropped and collides with the striker (66) as illustrated in FIG. 14, the core portion of the axial second end of the electrode assembly (20) rises axially outward as illustrated in FIGS. 15 and 16. Since the first electrode (21) is positioned radially inward relative to the second electrode (22), the impact of the striker (66) is generally concentrated on the first electrode (21). Accordingly, the rising information of the core portion is mainly acquired based on the first electrode (21). Of course, the rising information for the second electrode (22) can also be acquired.

[0152] Looking at FIGS. 15 and 16, it can be confirmed that the amount of rising detected from the rising result (see FIG. 16) of the electrode assembly (20) wound in a state where the winding tension (T) is set relatively small is greater than the amount of rising detected from the rising result (see FIG. 15) of the electrode assembly (20) wound in a state where the winding tension (T) is set relatively large.

[0153] Here, the number of core rise turns is measured by the number of turns at which the slitting surface (SS) of the first electrode (21) is raised. The core rise area (Ar) is calculated by multiplying the rise height of each rise turn by the width of each turn to obtain the cross-sectional area of ​​each rise turn, and then adding up the cross-sectional areas of all rise turns. The core rise height (Hr) of the electrode is measured by the height of the turn that rises the highest from the slitting surface (SS).

[0154] [Example 1]

[0155] Using the tester described above, a 4680 electrode assembly (20) with a 6 mm core wound under the following conditions was subjected to a crash test.

[0156] As Experimental Example 1, the core winding tension (Ts1) for the separator (28) of the electrode assembly (20) was set to 250 g.f., the middle winding tension (Ts2) to 400 g.f., and the outer circumference winding tension (Ts3) to 900 g.f., and the core winding tension (Te1) for the electrodes (21, 22) was set to 300 g.f., the middle winding tension (Te2) to 500 g.f., and the outer circumference winding tension (Te3) to 700 g.f., and then four electrode assemblies (20) were manufactured and tested.

[0157] As comparative example 1, the core part winding tension (Ts1) for the separator (28) of the electrode assembly (20) was set to 250 g.f., the middle part winding tension (Ts2) to 400 g.f., and the outer part winding tension (Ts3) to 900 g.f., and the core part winding tension (Te1) for the electrodes (21, 22) was set to 700 g.f., the middle part winding tension (Te2) to 900 g.f., and the outer part winding tension (Te3) to 1100 g.f., and then four electrode assemblies (20) were manufactured and tested.

[0158] And, in each test result, the results of measuring or calculating the number of core rise turns, core rise area, positive core rise height, and negative core rise height are as follows.

[0159] Comparative Example 1 Experimental Example 1 Core rise turn count Core rise area (mm) 2 ) Positive core rise height (mm) Negative core rise height (mm) Core rise turns Core rise area (mm) 2 ) Positive core rise height (mm) Negative core rise height (mm)#11536.2310.349.231564.5516.4614.45#21544.3911.648.331896.1518.0716.76#31840.119.015.921883.7012.6510.84#41436.2612.158.931776.7218.5714.86

[0160] Upon inspection, it can be confirmed that the degree of rise of the electrode assembly (20) wound under the winding tension conditions of Experimental Example 1 is greater. That is, compared to Comparative Example 1, it can be confirmed that the battery cell using the electrode assembly (20) wound under the winding conditions of Experimental Example 1 can quickly induce jelly-roll discharge in a thermal runaway situation.

[0161] [Example 2]

[0162] Next, a 4680 battery cell was manufactured with an electrode assembly (20) having a 6 mm core wound under the following conditions, and the battery cell was overcharged to induce thermal runaway.

[0163] As Experimental Example 2, the core winding tension (Ts1) for the separator (28) of the electrode assembly (20) was set to 250 g.f., the middle winding tension (Ts2) to 400 g.f., and the outer circumference winding tension (Ts3) to 900 g.f., and the core winding tension (Te1) for the electrodes (21, 22) was set to 300 g.f., the middle winding tension (Te2) to 500 g.f., and the outer circumference winding tension (Te3) to 700 g.f., and then a battery cell was manufactured using the wound electrode assembly (20) and thermal runaway was induced.

[0164] As Experimental Example 3, the core winding tension (Ts1) for the separator (28) of the electrode assembly (20) was set to 250 g.f., the middle winding tension (Ts2) to 400 g.f., and the outer circumference winding tension (Ts3) to 900 g.f., and the core winding tension (Te1) for the electrodes (21, 22) was set to 400 g.f., the middle winding tension (Te2) to 600 g.f., and the outer circumference winding tension (Te3) to 800 g.f., and then a battery cell was manufactured using the wound electrode assembly (20) and thermal runaway was induced.

[0165] As Experimental Example 4, the core winding tension (Ts1) for the separator (28) of the electrode assembly (20) was set to 250 g.f., the middle winding tension (Ts2) to 400 g.f., and the outer circumference winding tension (Ts3) to 900 g.f., and the core winding tension (Te1) for the electrodes (21, 22) was set to 500 g.f., the middle winding tension (Te2) to 700 g.f., and the outer circumference winding tension (Te3) to 900 g.f., and then a battery cell was manufactured using the wound electrode assembly (20) and thermal runaway was induced.

[0166] As comparative example 2, the core part winding tension (Ts1) for the separator (28) of the electrode assembly (20) was set to 250 g.f., the middle part winding tension (Ts2) to 400 g.f., and the outer part winding tension (Ts3) to 900 g.f., and the core part winding tension (Te1) for the electrodes (21, 22) was set to 600 g.f., the middle part winding tension (Te2) to 800 g.f., and the outer part winding tension (Te3) to 1000 g.f., and then a battery cell was manufactured using the wound electrode assembly (20) and thermal runaway was induced.

[0167] As comparative example 3, the core winding tension (Ts1) for the separator (28) of the electrode assembly (20) was set to 250 g.f., the middle winding tension (Ts2) to 400 g.f., and the outer circumference winding tension (Ts3) to 900 g.f., and the core winding tension (Te1) for the electrodes (21, 22) was set to 700 g.f., the middle winding tension (Te2) to 900 g.f., and the outer circumference winding tension (Te3) to 1100 g.f., and then a battery cell was manufactured using the wound electrode assembly (20) and thermal runaway was induced.

[0168] The rate at which lateral bursts occurred in each example and the extent of damage from lateral bursts are summarized in Table 2.

[0169] Overcharge Lateral Burst Rate Damage Risk Level Experimental Example 20% Level 0 (No pinhole, no battery cell melting, no lateral burst) Experimental Example 35% Level 1 (Pinhole in beading area) Experimental Example 411% Level 2 (Battery cell melting) Comparative Example 219% Level 2 (Battery cell melting) Comparative Example 324% Level 3 (Battery cell lateral bursting, total loss)

[0170] If we look at it, we can see that in Experimental Example 2, no lateral bursting occurs.

[0171] A battery cell having an electrode assembly (20) assembled by a winding method according to the present invention can prevent a rapid increase in the internal temperature and pressure of a can since the discharge of the electrode assembly (20) is smoothly performed in a thermal runaway situation. Accordingly, the phenomenon of the side wall of the can being damaged can be prevented. In addition, a battery module or battery pack including a battery cell having an electrode assembly (20) assembled by a winding method according to the present invention can prevent the thermal runaway from propagating and expanding to battery cells around the battery cell where the thermal runaway has occurred since the vent occurs in a designed direction without the lateral damage of the can even if a thermal runaway occurs in a specific battery cell.

[0172] 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.

[0173] 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 assembly in which a first electrode and a second electrode are wound around a core with a separator interposed therebetween; A can that houses the electrode assembly inside through an opening provided at the first axial end; and In a battery cell comprising a cap having an edge fixed to the can and covering the opening; The above electrode assembly is manufactured by winding the electrode and the separator while applying a predetermined winding tension to each of them, The above winding tension includes a core winding tension applied to the core section, an outer circumference winding tension applied to the outer circumference section, and an intermediate winding tension applied to the section between the core section and the outer circumference section. The outer circumference winding tension is greater than the middle section winding tension, and the middle section winding tension is greater than the core section winding tension. A battery cell in which the winding tension of the entire section for the above electrode is equal to or less than the winding tension of the outer circumference for the above separator.

2. A battery cell according to claim 1, wherein the winding tension of the entire section for the electrode is smaller than the winding tension of the outer circumference for the separator.

3. A battery cell according to claim 1, wherein the core winding tension for the electrode is equal to or less than the middle winding tension for the separator.

4. A battery cell according to claim 1, wherein the core winding tension for the electrode is smaller than the middle winding tension for the separator.

5. A battery cell according to claim 1, wherein the core winding tension for the electrode is greater than the core winding tension for the separator.

6. A battery cell according to claim 1, wherein the intermediate winding tension for the electrode is greater than the core winding tension and the intermediate winding tension for the separator.

7. In claim 1, the core winding tension for the electrode is 250 g.f. or more and 550 g.f. or less, The intermediate winding tension for the above electrode is 450 g.f. or more and 750 g.f. or less, A battery cell having an outer circumferential winding tension for the above electrode of 650 g.f. or more and 950 g.f. or less.

8. In claim 7, the core winding tension for the electrode is 250 g.f. or more and 450 g.f. or less, The intermediate winding tension for the above electrode is 450 g.f. or more and 650 g.f. or less, A battery cell having an outer circumferential winding tension of 650 g.f. or more and 850 g.f. or less for the above electrode.

9. In claim 8, the core winding tension for the electrode is 250 g.f. or more and 350 g.f. Below, The intermediate winding tension for the above electrode is 450 g.f. and less than or equal to 550 g.f., A battery cell having an outer circumferential winding tension of 650 g.f. or more and 750 g.f. or less for the above electrode.

10. In claim 1, the core winding tension for the separator is 200 g.f. or more and 300 g.f. Below, The intermediate winding tension for the above-mentioned separator is 300 g.f. or more and 500 g.f. or less, A battery cell having an outer circumferential winding tension of the above separator of 700 g.f. or more and 1100 g.f. or less.

11. In claim 10, the intermediate winding tension for the separator is 350 g.f. or more and 450 g.f. or less, A battery cell having an outer circumferential winding tension of the above separator of 800 g.f. or more and 1000 g.f. or less.

12. A battery cell according to claim 11, wherein the outer circumferential winding tension for the separator is 850 g.f. or more and 900 g.f. or less.

13. In claim 1, a beading portion processed by radially recessing the axial first end of the can; and Further comprising a crimping portion in which the axial first end of the can is bent radially inward; The edge of the above cap is interposed between the beading portion and the crimping portion of the can in the axial direction, the battery cell.

14. A method for winding an electrode assembly wound in a jelly-roll shape, The first electrode and the second electrode are wound around the core, and the first and second separators are interposed between the first and second electrodes and wound together. The above electrode and separator are wound while applying a predetermined winding tension to each of them. The winding is performed so that the intermediate winding tension applied in the middle section of the winding is greater than the core winding tension applied in the core section of the winding, and the outer circumference winding tension applied in the outer circumference section of the winding is greater than the intermediate winding tension applied in the middle section of the winding. A winding method for an electrode assembly, wherein the separator is wound in the outer peripheral section of the winding with an outer peripheral winding tension that is equal to or greater than the maximum winding tension of the entire section for the electrode.

15. A winding method for an electrode assembly according to claim 14, wherein the separator is wound in an outer peripheral section of the winding with an outer peripheral winding tension greater than the winding tension of the entire section for the electrode.

16. A winding method for an electrode assembly according to claim 14, wherein the separator is wound in the middle section of the winding with a middle section winding tension that is not less than the core section winding tension for the electrode.

17. A winding method for an electrode assembly according to claim 16, wherein the separator is wound in the middle section of the winding with a middle section winding tension greater than the core section winding tension for the electrode.

18. A winding method for an electrode assembly according to claim 14, wherein the electrode is wound in the middle section of the winding with a middle section winding tension greater than the winding tensions of the core section and the middle section for the separator.

19. In claim 14, the electrode has a core section of 250 g.f. Winding with a winding tension of 350 g.f. or less, and 450 g.f. in the middle section of the winding. It is wound with a winding tension of 550 g.f. or less, and 650 g.f. in the outer circumferential section of the winding. A method for winding an electrode assembly, wherein the winding is performed with a winding tension of 750 g.f. or less.

20. In claim 14, the separator has a core section of the coil of 200 g.f. Winding with a winding tension of 300 g.f. or less, and 350 g.f. in the middle section of the winding. It is wound with a winding tension of 450 g.f. or less, and 850 g.f. in the outer circumferential section of the winding. A method for winding an electrode assembly, wherein the winding is performed with a winding tension of 950 g.f. or less.

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