Cylindrical battery cell having current interruption function, battery pack including battery cell, and vehicle equipped with battery pack

Abstract

Provided is a battery cell having a current interruption function that is achieved by pressure. The battery cell includes a current collecting plate in which at least a portion of a circumferential region is bonded to an electrode assembly and thereby electrically connected to a first electrode of the electrode assembly, and at least a portion of a central region is bonded to and thereby electrically connected to a first electrode terminal mounted to a first end wall of a can. The first end wall partitions and shields the inner space of the can from the outside, and swells outward when the internal pressure of the can increases. The current collecting plate includes a fracture-inducing portion that is disposed in the central region and extends in a circumferential direction so as to surround a terminal bonding portion bonded to the first electrode terminal. The fracture-inducing portion fractures as bulging deformation of the first end wall increases.

Description

Cylindrical battery cell having current blocking function, battery pack including same, and vehicle equipped with said battery pack

[0001] This application claims the benefit of priority from Republic of Korea Patent Application No. 10-2024-0093728, dated July 16, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a cylindrical battery cell, and more particularly, to a battery cell having a current blocking function implemented by pressure, a battery pack including the same, and a vehicle equipped with the battery pack.

[0003] With the proliferation of electric vehicles, the capacity of cylindrical battery cells, manufactured using cylindrical battery cans as housings, is increasing. Furthermore, as battery cell sizes increase, it has become possible to position both the first and second electrode terminals on the top surface of a cylindrical battery cell. With both electrode terminals positioned on the top of the battery cell, multiple cylindrical battery cells can be mounted vertically, and bus bars for both electrode terminals can be positioned on top of the battery cells, further simplifying the structure of vehicle battery packs.

[0004] Referring to FIGS. 1 and 2, a conventional cylindrical battery cell has a structure in which a first end wall (12) connected to an axial first end of a side wall (11) of a cylindrical can (10) and extending radially is disposed at the bottom, a jelly-roll-shaped electrode assembly (20) is accommodated in the internal space of the can (10), and an opening provided at an axial second end of the side wall (11) is covered and finished with a cap assembly (90).

[0005] Referring to FIG. 3, the cap assembly (90) has a positive terminal (91) positioned at the top, a current blocking disk (93) positioned at the bottom, an inversion disk (92) positioned between the positive terminal (91) and the current blocking disk (93), and an insulating spacer (94) that maintains a distance between the current blocking disk (93) and the inversion disk (92).

[0006] The central portion of the positive terminal (91) protrudes upward to provide a terminal surface, and the edge is joined to the edge of the inverted disk (92). An exhaust hole (910) through which vent gas can be discharged is formed between the central portion and the edge.

[0007] The above-mentioned inversion disk (92) includes a vent notch portion (923) that can be broken when the internal pressure of the can (10) becomes high, an inversion portion (921) that extends downwardly inwardly in the radial direction from the vent notch portion (923), and a joint portion (922) arranged in the central portion.

[0008] The edge of the current blocking disk (93) is insulated and separated from the reversing disk (92) by the insulating spacer (94), and a joint (934) is provided in the center to be joined to the joint (922), and a fracture-inducing portion (935) with weakened strength is provided around the joint (922).

[0009] The positive electrode collector plate (30) is connected to the positive electrode of the electrode assembly (20) and to the edge of the current blocking disk (93).

[0010] Accordingly, in a normal state, the positive electrode of the electrode assembly (20) is electrically connected to the current blocking disk (93) through the positive electrode collector (30), the current blocking disk (93) is electrically connected to the reverse disk (92) through the joint portion (934, 922), and the current blocking disk (93) is electrically connected to the positive electrode terminal (91) through the joint portion at the edge.

[0011] When an overcurrent flows between the positive electrode of the electrode assembly (20) and the positive electrode terminal (91), the temperature of the neck portion of the positive electrode collector (30) that implements a fuse function rapidly rises and begins to melt, thereby cutting off the current.

[0012] When the pressure inside the can rises, the inverting portion (921) of the inverting disk (92) that seals the internal space of the can from the external space is inverted, causing the joint portions (922, 934) to rise upward. At this time, the rupture inducing portion (935) is broken, and the current between the positive electrode of the electrode assembly (20) and the positive electrode terminal (91) is cut off.

[0013] If the pressure in the internal space of the can (10) further increases even after the inversion part (921) is inverted by internal pressure, the vent notch part (923) of the inversion disk (92) is broken, the internal space of the can is opened to the external space, and the vent gas inside the can (10) is discharged to the outside through the exhaust hole (910).

[0014] However, the cap assembly (90) structure of this conventional battery cell is disadvantageous for application to a high-capacity battery cell with high energy density because it takes up a lot of internal space of the battery cell.

[0015] The present invention has been derived to solve the above-described problems, and aims to provide a battery cell having a high energy density while having a structure capable of cutting off current due to an increase in internal pressure of the battery cell.

[0016] The present invention aims to provide a battery cell having a compact structure comprising a rupture structure capable of cutting off current due to an increase in internal pressure and a fuse structure due to overcurrent.

[0017] The present invention seeks to provide a battery cell capable of preventing explosion due to increased internal pressure.

[0018] The present invention provides a battery pack including a high energy density battery cell having a structure capable of preventing thermal runaway and explosion due to overcurrent and pressure increase, and a vehicle equipped with such a battery pack.

[0019] 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.

[0020] The present invention, in order to solve the above-described problem, provides a current collector plate manufactured in a substantially flat shape and provided with a rupture structure capable of interrupting current by breaking due to an increase in internal pressure of a battery cell.

[0021] Additionally, the collector plate may include a fuse structure for overcurrent protection. The fuse structure may be implemented independently so as not to affect the operation of the rupture structure.

[0022] The battery cell may include a housing having a side wall extending in an axial direction and surrounding an internal space in a circumferential direction, a first end wall connected to a first end of the side wall in the axial direction and extending radially to cover the internal space, and a second end wall connected to a second end of the side wall in the axial direction opposite the first end and extending radially to cover the internal space.

[0023] The above housing may be, for example, a can.

[0024] The first end wall can shield and partition the internal space and the external space of the can. In other words, the first end wall serves as a partition that maintains a pressure difference between the internal space and the external space.

[0025] The battery cell may include a first electrode terminal installed through the first end wall so as to be electrically insulated from the first end wall.

[0026] The above first end wall can form a second electrode terminal having a different polarity from the first electrode terminal.

[0027] The above first end wall can be electrically connected to the side wall.

[0028] In some examples, the bulging resistance of the first end wall may be designed to be smaller than the bulging resistance of the second end wall.

[0029] Specifically, the average thickness of the first end wall may be thinner than the average thickness of the second end wall. Accordingly, when the internal pressure increases, the bulging phenomenon of the first end wall may be induced more than that of the second end wall.

[0030] In some examples, the radius of curvature of the side wall with respect to the central axis of the internal space may be smaller than the average radius of curvature of the first end wall with respect to a center existing on an imaginary axis extending along the axial direction of the central axis. For example, the first end wall may have a flat plate shape substantially perpendicular to the central axis, and the side wall may have a cylindrical shape parallel to the central axis. Accordingly, when the internal pressure increases, the bulging phenomenon of the first end wall may be induced more than that of the side wall.

[0031] In some examples, either the first end wall or the second end wall may be monolithically connected to the side wall.

[0032] Specifically, the first end wall can be connected to the side wall in a monolithic manner.

[0033] In some examples, at least one of the first end wall and the second end wall may be coupled to the side wall.

[0034] Specifically, the second end wall can be combined with the side wall.

[0035] The above-mentioned joining method may be compression fixation through beading and crimping processing.

[0036] The above-mentioned joining method may be bonding. Specifically, the joining method may include any one of welding, brazing, and soldering.

[0037] In some examples, either the first end wall or the second end wall may include a vent notch portion formed to have a reduced thickness and extending circumferentially.

[0038] Specifically, the vent notch portion may be provided on the first end wall. The vent notch portion may extend to surround the first electrode terminal.

[0039] An electrode assembly including a first electrode and a second electrode can be accommodated in the above internal space.

[0040] The first electrode terminal may be electrically connected to the first electrode, and the first end wall may be electrically connected to the second electrode.

[0041] The above electrode assembly may have a structure in which a separator is interposed between the first electrode and the second electrode and is wound around a core hollow portion extending in the axial direction.

[0042] The electrode tab of the first electrode may be arranged at the axial first end of the electrode assembly. Specifically, the electrode tab may include a portion of the current collector of the first electrode, on which no active material is applied, exposed to the axial first end of the electrode assembly.

[0043] The current collector of the first electrode exposed to the axial first end of the electrode assembly may be provided by being bent in a radial direction. Specifically, the bending direction may be a direction toward the central axis of the battery cell.

[0044] The first electrode terminal and the first electrode of the electrode assembly are electrically connected to each other through the current collector plate.

[0045] The above-mentioned current collector plate includes a central portion facing the first electrode terminal in the axial direction and a peripheral portion surrounding the central portion.

[0046] At least a portion of the peripheral portion is electrically connected to the first electrode by being joined, and at least a portion of the central portion is electrically connected to the first electrode terminal by being joined.

[0047] Specifically, the terminal joint positioned in the central portion and joined to the first electrode terminal can be welded to the first electrode terminal.

[0048] Specifically, the peripheral portion of the current collector plate can be joined to the electrode tab. More specifically, the electrode tab, which is bent radially, can be joined such that the surface facing the axial outer side is in contact with the axial inner surface of the peripheral portion.

[0049] The electrode joint positioned on the above-mentioned circumference and joined to the electrode tab can be welded to the electrode tab. Specifically, the welding can be penetration welding using a laser irradiated onto the surface of the first collector plate.

[0050] The above electrode joints may be in a radially extended form. A plurality of the above electrode joints may be spaced apart from each other along the circumferential direction.

[0051] The above-mentioned current collector plate includes a fracture-inducing portion extending circumferentially to surround the terminal joint.

[0052] In some examples, the thickness of the fracture inducing portion may be thinner than the thickness of the central portion radially outer and inner.

[0053] In some examples, the tensile strength of the fracture inducing portion, measured radially, may be lower than the tensile strength of the central portions radially outer and inner therefrom.

[0054] In some examples, the fracture inducing portion may extend in an open loop or closed loop form along an imaginary fracture line surrounding the terminal joint.

[0055] In some examples, the fracture inducing portion may extend continuously or discretely along a virtual fracture line surrounding the terminal joint.

[0056] In some examples, the central portion and the peripheral portion may be spaced apart from each other radially.

[0057] In some examples, the terminal junction and the electrode junction may be spaced apart from each other in a radial direction.

[0058] The above-mentioned fracture-inducing portion can be arranged radially between the terminal joint portion and the electrode joint portion.

[0059] The above-mentioned collector plate may further include a bridge arranged radially between the central portion and the peripheral portion.

[0060] Preferably, the fracture inducing portion may be provided in the central portion.

[0061] In some examples, the bridge may extend longitudinally with a predetermined width. A first longitudinal end of the bridge may be connected to the peripheral portion, and a second longitudinal end of the bridge may be connected to the central portion. The peripheral portion and the central portion may be electrically connected to each other by the bridge.

[0062] In some examples, the bridge may extend radially, a radially inner end of the bridge may be connected to the central portion, and a radially outer end of the bridge may be connected to the peripheral portion.

[0063] Specifically, the above bridges may be arranged in multiple spaced apart configurations along the circumferential direction. More specifically, the plurality of above bridges may extend radially from the terminal joint.

[0064] Preferably, the bridge may be a fuse structure of the collector plate.

[0065] Preferably, the tensile strength of the fracture inducing portion measured in the radial direction may be lower than the sum of the tensile strengths of all bridges measured in the radial direction.

[0066] The present invention further provides a battery pack comprising the battery cell and a pack case housing the battery cell.

[0067] The present invention further provides a vehicle equipped with the battery pack and driven by power from the battery pack.

[0068] The battery cell of the present invention can induce bulging of the first end wall as the internal pressure increases. Accordingly, the first electrode terminal fixed to the first end wall moves axially outward, and the terminal joint portion of the central portion of the first collector plate joined thereto also moves axially outward. On the other hand, the electrode joint portion of the peripheral portion of the first collector plate is joined to the electrode tab of the electrode assembly, thereby preventing axial movement. Accordingly, a tensile force is applied to the fracture-inducing portion in a radial direction. When the fracture-inducing portion is fractured by the tensile force, the electrical connection between the first electrode of the electrode assembly and the first electrode terminal can be cut off.

[0069] According to the present invention, since the electrode tab of the first electrode of the electrode assembly is bent radially inward, when the central portion of the first collector plate tries to move axially outward, the peripheral portion of the first collector plate is very effectively prevented from moving radially inward as well. In addition, since the electrode joint extends radially, the peripheral portion of the first collector plate can be more strongly fixed.

[0070] According to the present invention, the fracture-inducing portion is arranged radially between the electrode joint portion and the terminal joint portion, so that a tensile force acting in the radial direction can be concentrated on the fracture-inducing portion.

[0071] According to the present invention, the bridge of the first collector plate is arranged radially outside the central portion and can perform a fuse function independently of the rupture inducing portion.

[0072] According to the present invention, the bridge of the first collector plate extends radially around the terminal joint, so that when bulging of the first end wall occurs, the tensile force can be concentrated on the blocking induction portion.

[0073] According to the present invention, both the fuse structure and the rupture structure are implemented on a substantially flat first collector plate, thereby minimizing the internal volume of the battery cell occupied by the above structure. Consequently, the energy density of the battery cell can be increased.

[0074] According to the present invention, by implementing both a fuse structure and a rupture structure in the first collector plate, thermal runaway of a battery cell can be prevented, and by forming a notched vent portion in the first end wall of the can, when the internal pressure of the can increases, the first end wall ruptures to discharge vent gas, thereby preventing explosion of the can, and in particular, the phenomenon of the side wall of the can rupturing can be prevented.

[0075] The battery cell of the present invention has a large capacity with high energy density while having a structure that prevents thermal runaway and explosion, and is therefore very advantageous for use in a vehicle battery pack.

[0076] Vehicles equipped with battery packs using the above battery cells can reduce the volume of the battery pack, thereby securing more interior space in the vehicle, and can further extend the vehicle's driving range due to its high energy density.

[0077] 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.

[0078] Figure 1 is a perspective view showing a comparative form of a cylindrical battery cell.

[0079] Figure 2 is a cross-sectional view of the battery cell of Figure 1.

[0080] Figure 3 is an enlarged view of the cap assembly portion of the battery cell of Figure 2.

[0081] Figure 4 is an exploded perspective view of an electrode assembly housed inside a can of a battery cell of an embodiment before winding.

[0082] Fig. 5 is a perspective view of the electrode assembly of Fig. 4 in a pre-winding laminated state.

[0083] Fig. 6 is a perspective view of an assembled cylindrical jelly-roll-shaped electrode assembly by winding up the laminate of Fig. 5.

[0084] Fig. 7 is a perspective view showing a state in which a first collector plate is joined to an electrode tab provided at an axial first end of an electrode assembly facing the first end wall of a can.

[0085] Fig. 8 is a perspective view showing a state in which a second collector plate is joined to an electrode tab provided on an axial second end of an electrode assembly facing a second end wall or opening of a can.

[0086] Fig. 9 is a cross-sectional view of a battery cell of the first embodiment.

[0087] Fig. 10 is a cross-sectional view of a battery cell of the second embodiment.

[0088] Figure 11 is a plan view of the first collector plate.

[0089] Figure 12 is a cross-sectional view taken along line XII-XII of Figure 11.

[0090] Figure 13 is a cross-sectional view taken along line XIII-XIII of Figure 11.

[0091] Figure 14 is an enlarged cross-sectional view of the axial first end portion of the battery cell before the internal pressure increases.

[0092] Fig. 15 is a cross-sectional view of the battery cell of Fig. 14 in which the internal pressure has increased and the first end wall has bulged.

[0093] Fig. 16 is a cross-sectional view showing a state in which the internal pressure of the battery cell of Fig. 15 further increases and the fracture inducing portion of the first collector plate is fractured.

[0094] Fig. 17 is a drawing showing a battery pack having the battery cell of Fig. 10 built into a pack housing.

[0095] Fig. 18 is a drawing showing a vehicle equipped with the battery pack of Fig. 17.

[0096] [Explanation of symbols]

[0097] 10: Can 11: Side wall 113: Beading part 115: Crimping part 12: First end wall 13: Vent notch part 15: Cap gasket 16: Second end wall 17: First electrode terminal 170: Terminal gasket 19: Insulator 20: Electrode assembly 21: First electrode 22: Second electrode 23: Metal foil (current collector) 24: Active material layer (active material) 25: Holding part 26: Non-coated part 27: Electrode tab (notched tab) 28: Separator 29: Core hollow part 30: First current collector 31: Peripheral part 310: First electrode junction part 32: Central part 320: Terminal junction part 33: Bridge 34: Fracture inducing part 40: Second current collector 41: Center part 410: Second electrode junction 42: Frame 43: Connection 70: Battery pack 71: Pack case 72: Battery cell 80: Vehicle 90: Cap assembly 91: Positive terminal 910: Exhaust hole 92: Inverting disk 921: Inverting portion 922: Joint 923: Vent notch portion 93: Current blocking disk 934: Joint 935: Fracture inducing portion 94: Insulating spacer

[0098] 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.

[0099] 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.

[0100] Throughout the specification, unless otherwise specifically stated, each element may be singular or plural.

[0101] 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.

[0102] Additionally, when it is described that a component is "connected," "coupled," or "contacted" with another component, it should be understood that the components may be directly connected or in contact with each other, but that other components may also be "interposed" between the components, or that each component may be "connected," "coupled," or "contacted" through another component.

[0103] 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.

[0104] 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.

[0105] In describing the embodiment, the axial direction refers to the direction in which the axis forming the winding center of the jelly-roll type electrode assembly extends, the radial direction (radial direction) refers to the direction closer to or farther from the axis, and the circumferential direction (circumferential direction) refers to the direction surrounding the axis.

[0106] Hereinafter, a cylindrical battery cell according to an embodiment of the present invention will be described with reference to FIGS. 4 to 16.

[0107] Referring to FIGS. 8 and 9, a cylindrical battery cell according to an embodiment of the present invention includes an electrode assembly (20), a current collector (30, 40) electrically connected to the electrode assembly (20), and a can (10) that accommodates the electrode assembly (20) and the current collector (30, 40).

[0108] Referring to FIGS. 4 to 6, the electrode assembly (20) is prepared by preparing a first electrode (21), a second electrode (22), and a separator (28) that extend in the longitudinal direction with a predetermined width (see FIG. 4), and then stacking them in the order of the first electrode (21), the separator (28), the second electrode (22), and the separator (28) as shown in FIG. 5, and manufacturing them in the form of a jelly-roll wound around a core shaft (see FIG. 6).

[0109] 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.

[0110] The first electrode (21) and the second electrode (22) are manufactured in the form of sheets that extend in the longitudinal direction with a predetermined width. The electrode sheet is manufactured in the form in which an active material (24) is applied to the surface of a current collector (23) such as a metal foil. The current collector has a holding portion (25) region where the active material (24) is applied, and a non-conductive portion (26) region where the active material (24) is not applied. The current collector (23) of the first electrode (21) has a non-conductive portion (26) region at a first end in the width direction, and the current collector (23) of the second electrode (22) has a non-conductive portion (26) region at a second end in the width direction.

[0111] The non-conductive portion (26) region of the current collector (23) of the first electrode (21) and the second electrode (22) is exposed or protrudes from the laminated body as the first end and the second end in the width direction, respectively, as shown in Fig. 5. The non-conductive portion (26) itself functions as an electrode tab (27).

[0112] In the above-mentioned blank portion (26), notches can be formed at a predetermined interval to form flag-shaped electrode tabs (27).

[0113] In the embodiment, the electrode tabs (27) are exemplified as having an equilateral trapezoidal shape. However, their shapes may be various, such as a semicircle, a semi-ellipse, a triangle, a rectangle, or a parallelogram.

[0114] In addition, in the embodiment, a form in which the electrode tabs (27) arranged along the longitudinal direction have the same width is exemplified. However, the width of the electrode tabs may be gradually or stepwise widened from the core side to the outer periphery side.

[0115] In addition, in the embodiment, a form in which the height of the electrode tabs (27) gradually increases from the core side to the outer circumference side is exemplified. However, the height of these electrode tabs may be implemented in a form in which they are constant or gradually decrease.

[0116] In addition, in the embodiment, a structure is exemplified in which the electrode tab (27) is deleted in a predetermined section of the centrifugal end of the non-conductive portion (26) and a predetermined section of the centrifugal end. However, it is of course possible that the electrode tab may not be deleted in the centrifugal end of the non-conductive portion, or that the electrode tab may not be deleted in the centrifugal end of the non-conductive portion, or that neither may be deleted.

[0117] In the jelly roll-shaped electrode assembly (20), the electrode tab (27) can be bent radially and flattened as shown in Fig. 6. The electrode tab (27) can be bent radially inward or outward. Preferably, the electrode tab (27) can be bent radially inward.

[0118] The above electrode tabs (27) can be bent one by one during the process of forming a jelly roll-shaped electrode assembly (20) by winding the laminate. Alternatively, the electrode tabs (27) can be bent all at once after the laminate is wound to form a jelly roll-shaped electrode assembly.

[0119] The electrode tabs (27) of the first electrode (21) and the electrode tabs (27) of the second electrode (22), which are bent and overlapped in the radial direction in this way, can provide a first plane and a second plane that are substantially perpendicular to the axial direction at the axial ends of the electrode assembly (20), respectively.

[0120] The electrode tabs (27) exposed at both axial ends of the electrode assembly (20) are bent to provide substantially flat first and second surfaces, and a first collector plate (30) and a second collector plate (40) can be joined to them, as shown in FIGS. 7 and 8.

[0121] In the embodiment, the first collector plate (30) is exemplified as a positive collector plate and the second collector plate (40) is a negative collector plate. However, the first collector plate (30) may be a negative collector plate and the second collector plate (40) may be a positive collector plate.

[0122] The second collector plate (40) may include a copper material, and the first collector plate (30) may include an aluminum material. However, the materials are not limited thereto.

[0123] The above-mentioned collector plate (30, 40) can be manufactured by punching, trimming, piercing, drawing or bending a metal plate or metal sheet.

[0124] Referring to FIGS. 7, 11 to 13, the first collector plate (30) includes a central portion (32) provided at a portion corresponding to the core hollow portion (29) of the electrode assembly (20), and a peripheral portion (31) provided around the central portion (32). The central portion (32) is disposed at the center of the first collector plate (30) and is provided in a form that axially covers at least a portion of the core hollow portion (29) of the electrode assembly (20). In an embodiment, the central portion (32) is implemented in the form of a substantially circular plate or flat plate. The peripheral portion (31) is spaced apart from the central portion (32) in the radial direction and surrounds the central portion (32). In an embodiment, the peripheral portion (31) is implemented in the form of a substantially circular ring that is concentric with the central portion (32).

[0125] The central portion (32) and the peripheral portion (31) are physically and electrically connected to each other through a bridge (33). The bridge (33) is disposed radially between the central portion (32) and the peripheral portion (31). The bridge (33) has a predetermined width in the circumferential direction and extends radially by a predetermined length. A first longitudinal end of the bridge (33) provided on the radially outer side is connected to the peripheral portion (31), and a second longitudinal end of the bridge (33) provided on the radially inner side is connected to the central portion (32). A plurality of bridges (33) are provided, and the plurality of bridges (33) are spaced apart from each other along the circumferential direction. Preferably, the plurality of bridges (33) may extend radially from a terminal connection portion (320) provided on the central portion (32) and be spaced apart from each other at equal intervals in the circumferential direction. More preferably, the plurality of bridges (33) may include at least one pair of bridges (33) arranged substantially in the same straight line with the terminal joint (320) as the center.

[0126] In some examples, the terminal joint (320) may be an area provided at the center of the central portion (32). That is, the remaining area of ​​the central portion (32) and the terminal joint (320) area may be formed in the same flat plate, as illustrated in FIG. 9.

[0127] In some examples, the terminal joint (320) may be in the form of a circular protrusion protruding upward from the center of the central portion (32). That is, as illustrated in FIGS. 7 and 12 to 14, an area in which the upper surface of the center of the central portion (32) protrudes upward and the lower surface is sunken upward may constitute the terminal joint (320). The terminal joint (320) may be fitted into a groove provided on the bottom surface of the first electrode terminal (17).

[0128] The above peripheral portion (31) and the central portion (32) are electrically connected to each other by the bridge (33). If the peripheral portion (31) and the central portion (32) are electrically connected to each other only through the bridge (33), the width and length of the bridge (33) can be appropriately adjusted to provide a fuse function to the bridge (33).

[0129] The first plane provided by the electrode tabs (27) of the first electrode (21) bent radially inward faces the circumference (31) in the axial direction.

[0130] The first current collector plate (30) is electrically connected to the first electrode (21) of the electrode assembly (20) by being joined to the electrode tabs (27) of the first electrode (21) at the first electrode joints (310) provided on at least a portion of the circumferential portion (31). The first electrode joints (310) may be portions that are penetratedly welded to the electrode tabs (27) by a laser irradiated onto the surface of the first current collector plate (30). Each first electrode joint (310) extends in the radial direction, and a plurality of first electrode joints (310) are spaced apart from each other along the circumferential direction of the circumferential portion (31).

[0131] In order to further secure the bonding area of ​​the first electrode joint (310) of the first collector plate (30), the radially inner peripheral portion of the peripheral portion (31) extends radially inwardly in the region between the plurality of bridges (33) in the circumferential direction. That is, the peripheral portion (31) has a ring-shaped main body portion extending in the circumferential direction and a fan-shaped extension portion connected to the inner periphery thereof. The first electrode joint (310) can be formed radially on the main body portion and the extension portion.

[0132] A terminal connection portion (320) is provided in the central portion (32) of the first current collector plate (30), which faces the first electrode terminal (17) in the axial direction and is connected to the first electrode terminal (17). The terminal connection portion (320) may be a portion where the central portion (32) is welded to the first electrode terminal (17). Accordingly, the first electrode terminal (17) and the first electrode (21) of the electrode assembly (20) are electrically connected to each other through the first current collector plate (30).

[0133] The first collector plate (30) includes a fracture-inducing portion (34) extending circumferentially to surround the terminal joint portion (320). Preferably, the fracture-inducing portion (34) may be provided in the central portion (32). Accordingly, the bridge (33) and the fracture-inducing portion (34) may be arranged to be spatially spaced from each other.

[0134] In the embodiment, the fracture-inducing portion (34) is implemented by notching the surface of the first collector plate (30) to make it thinner. Accordingly, the thickness of the fracture-inducing portion (34) is configured to be thinner than the thickness of the first collector plate (30) portions on the radially outer and inner sides adjacent thereto. Then, the stress generated by the tensile force applied radially around the terminal joint portion (320) can be amplified in the fracture-inducing portion (34).

[0135] However, the method of implementing the fracture induction unit (34) is not limited to this.

[0136] In addition to this, the material constituting the fracture-inducing portion (34) may be configured to be different from the material of the radially outer and inner portions of the adjacent first collector plate (30), so that the tensile strength of the fracture-inducing portion (34) is weaker than the tensile strength of the material of the radially outer and inner portions of the adjacent first collector plate (30), thereby implementing the fracture-inducing portion (34).

[0137] The above-mentioned fracture-inducing portion (34) is extended in a closed loop shape along a virtual fracture line surrounding the terminal joint portion (320). However, if fracture can be induced along the fracture line, the fracture-inducing portion (34) can also be extended in an open loop shape.

[0138] The above-mentioned fracture-inducing portion (34) extends continuously along an imaginary fracture line surrounding the terminal joint portion (320). However, if fracture can be induced along the intended fracture line, the fracture-inducing portion (34) can also be extended discretely.

[0139] The above-described rupture inducing unit (34) can be implemented independently of the function of the fuse of the bridge (33) described above, and can be implemented in a way that minimizes the influence of the rupture inducing unit (34) on the fuse function of the bridge (33).

[0140] Specifically, since the bridge (33) has a large strength to resist the tensile force applied in the radial direction, the bridge (33) can have almost no influence on the rupture phenomenon of the rupture-inducing portion (34) due to the tensile force. To this end, within the range where the function of the fuse can be implemented, the width of the bridge (33) can be set as large as possible, and the length can be set as short as possible. In addition, the rupture-inducing portion (34) can be set to have a material or thickness that does not significantly increase the electrical resistance compared to the radially outer and inner portions thereof.

[0141] In a state where the first collector plate (30) is installed in the battery cell, the portions that fix the first collector plate (30) are the terminal joint (320) and the first electrode joint (310). According to an embodiment, around the terminal joint (320), the first electrode joint (310) is spaced apart from the terminal joint (320) in the radial direction. And the fracture inducing portion (34) is disposed between the terminal joint (320) and the first electrode joint (310) in the radial direction.

[0142] Accordingly, when the terminal joint (320) moves along the axial direction so as to be relatively distant from the first electrode joint (310), a tensile force is generated between the first electrode joint (310) and the terminal joint (320) radially centered on the terminal joint (320), and this tensile force acts on the fracture inducing portion (34).

[0143] Meanwhile, referring to FIG. 8, the second collector plate (40) includes a ring-shaped center portion (41) having a hole formed in the center, and a rim portion (42) surrounding the center portion (41) on the radially outer side of the center portion (41). The center portion (41) and the rim portion (42) are spaced apart from each other in the radial direction. The center portion (41) and the rim portion (42) are physically and electrically connected to each other through a plurality of connecting portions (43) extending radially with respect to the central axis.

[0144] In the above center portion (41), a plurality of second electrode joints (410) are provided that are penetrately welded to the electrode tabs (27) of the second electrode (22) of the electrode assembly (20) by radially extending laser welding lines. The plurality of second electrode joints (410) are spaced apart from each other along the circumferential direction, avoiding the connection portion (43).

[0145] The above-mentioned edge portion (42) is electrically connected to the can (10) by being joined to the side wall (11) and / or the second end wall (16) of the can (10).

[0146] Referring to FIGS. 9 and 10, the battery cell includes a can (10) having an internal space that accommodates the electrode assembly (20).

[0147] The can (10) has a side wall (11) extending along an axial direction and surrounding an internal space in a circumferential direction, a first end wall (12) connected to a first end of the side wall in the axial direction and extending radially to cover the internal space, and a second end wall (16) connected to a second end of the side wall in the axial direction opposite to the first end in the axial direction and extending radially to cover the internal space.

[0148] The first electrode terminal (17), which is electrically connected to the first electrode (21) of the electrode assembly (20), is installed through the can (10). The first electrode terminal (17) is installed through the first end wall (12) so as to be electrically insulated from the first end wall (12). The first electrode terminal (17) is installed in the central portion of the first end wall (12).

[0149] Between the first end wall (12) and the first electrode terminal (17), a terminal gasket (170) having electrical insulation and high sealing properties is press-fitted.

[0150] The first end wall (12) seals and partitions the internal space of the can from the external space of the can. In other words, the first end wall (12) serves as a partition that maintains a pressure difference between the internal space of the can (10) and the external space.

[0151] According to the present invention, in order to form an opening for inserting an electrode assembly (20) into the internal space of the can (10), at least one of the first end wall (12) and the second end wall (16) can be assembled with the side wall (11). In the embodiment, the second end wall (16) is assembled and connected with the side wall (11).

[0152] In a state where the electrode assembly (20) is accommodated in the internal space of the can (10), the first collector plate (30) installed at the axial first end of the electrode assembly (20) faces the first end wall (12) and the first electrode terminal (17), and the second collector plate (40) installed at the axial second end of the electrode assembly (20) faces the second end wall (16) or the opening.

[0153] The first end wall (12) may be connected to the side wall (11) before inserting the electrode assembly (20) into the internal space of the can (10).

[0154] The above first end wall (12) may be manufactured as a separate part from the side wall (11) and then connected to the axial first end of the side wall (11), or may be formed integrally with the side wall (11) from the beginning and connected in a monolithic manner.

[0155] The present invention utilizes a phenomenon in which a first end wall (12) bulges outward in the axial direction when the internal pressure of the can (10) increases, thereby causing the fracture-inducing portion (34) of the first current collector (30) to fracture due to the deformation, thereby interrupting the current between the first electrode terminal (17) and the first electrode (21) of the electrode assembly (20). To this end, it is preferable to control the deformation resistance of the first end wall (12) below a certain level so that the deformation of the first end wall (12) can increase in response to the increase in the internal pressure of the can (10).

[0156] According to the present invention, the bulging resistance of the first end wall (12) can be set to be smaller than the bulging resistance of the second end wall (16). Accordingly, when the internal pressure of the can (10) increases, the bulging phenomenon of the first end wall (12) can be induced more than that of the second end wall (16).

[0157] According to an embodiment, the average thickness of the first end wall may be thinner than the average thickness of the second end wall. The structure in which the first end wall (12) is formed integrally with the side wall (11) and connected in a monolithic form is advantageous in that the thickness of the first end wall (12) is configured to be thinner compared to the structure in which the edge of the first end wall (12) is bonded to the side wall (11).

[0158] According to the present invention, the bulging resistance of the first end wall (12) can be set to be smaller than the bulging resistance of the side wall (11). Accordingly, when the internal pressure increases, the bulging phenomenon of the first end wall (12) can be induced more than that of the side wall (11).

[0159] According to an embodiment, the radius of curvature of the side wall (11) with respect to the central axis of the internal space may be smaller than the average radius of curvature of the first end wall (12) with respect to a center existing on an imaginary axis extending along the axial direction of the central axis.

[0160] For example, when the side wall (11) is in the form of a tube having a first diameter and the first end wall (12) has a shape substantially corresponding to a portion of the surface of a sphere having a second diameter, a case in which the second diameter is significantly larger than the first diameter can be exemplified. Specifically, when the first end wall (12) has a flat plate shape substantially perpendicular to the central axis, the second diameter may be close to infinity, while the first diameter may be approximately 46 mm.

[0161] In the embodiment, the second collector plate (40) can be electrically connected to the side wall (11) by having the edge portion (42) bonded to the side wall (11) or by having the edge portion (42) bonded to the second end wall (16) bonded to the side wall (11). In addition, the first end wall (12) can be electrically connected to the side wall (11). Accordingly, the first end wall (12) can form a second electrode terminal having a different polarity from the first electrode terminal (17).

[0162] In order to electrically insulate the first collector plate (30) from the first end wall (12), an insulator (19) is interposed between the first collector plate (30) and the first end wall (12) in the axial direction. The insulator (19) is not interposed in the area where the terminal joint (320) of the first collector plate (30) and the first electrode terminal (17) face each other in the axial direction.

[0163] The terminal joint (320) of the first collector plate (30) is joined to the bottom surface of the first electrode terminal (17) by welding or the like. The joint strength thereof is sufficiently high to resist the radial tensile force applied to the first collector plate (30) until the fracture inducing portion (34) of the first collector plate (30) described above is fractured.

[0164] In a state where the electrode assembly (20) is inserted into the can (10) and the terminal connection portion (320) of the first collector plate (30) is connected to the first electrode terminal (17), the second end wall (16) can be connected to the axial second end portion of the side wall (11).

[0165] In the battery cell structure of the first embodiment illustrated in Fig. 9, the edge of the second end wall (16) is axially and radially wrapped and compressed by the beading portion (113) and crimping portion (115) of the side wall (11) with the cap gasket (15) interposed therebetween. At this time, the edge portion (42) of the second collector plate (40) is interposed between the beading portion (113) and the edge of the second end wall (16) in the axial direction and can be brought into close contact with the side wall surface of the beading portion (113).

[0166] Accordingly, the second electrode (22) of the electrode assembly (20) is electrically connected to the second collector plate (40), the side wall (11), and the first end wall (12).

[0167] In the battery cell structure of the second embodiment illustrated in Fig. 10, the edge of the second end wall (16) is joined to the axial second end of the side wall (11). And the edge portion (42) of the second current collector (40) is welded together to the joint portion of the side wall (11) and the second end wall (16).

[0168] Accordingly, the second electrode (22) of the electrode assembly (20) is electrically connected to the second collector plate (40), the second end wall (16), the side wall (11), and the first end wall (12).

[0169] Meanwhile, in the embodiment, either the first end wall (12) or the second end wall (16) has a vent notch portion (13) that is ruptured when the internal pressure rises above the reference pressure to open the internal space of the can (10) to the outside. The vent notch portion (13) may be in the form of a notch formed to have a reduced thickness and extending in the circumferential direction.

[0170] In the first embodiment shown in Fig. 9, the vent notch portion (13) is provided on the second end wall (16).

[0171] In the second embodiment illustrated in Fig. 10, the vent notch portion (13) is provided in the first end wall (12). The vent notch portion (13) may extend in a closed loop shape along the circumferential direction to surround the first electrode terminal. The vent notch portion (13) may have a closed loop or an open loop shape. For example, the vent notch portion (13) may extend in an "O" or "C" shape. Accordingly, when the pressure inside the battery cell exceeds a predetermined dangerous pressure value, the vent notch portion (13) is damaged, opening the first end wall (12), so that the pressure inside the battery cell is released to the external space.

[0172] Referring to Fig. 14, in a normal state, the first end wall (12) of the battery cell maintains a flat shape without being deformed, and the first collector plate (30) having a central portion (32) joined to the first electrode terminal (17) and a peripheral portion (31) joined to the electrode tab (27) of the first electrode (21) of the electrode assembly (20) also maintains a flat shape and electrically connects the first electrode terminal (17) and the first electrode (21) of the electrode assembly (20).

[0173] When an abnormal situation occurs in which an overcurrent flows between the first electrode terminal (17) and the first electrode (21) of the electrode assembly (20), the amount of heat generated by the bridge (33) of the first collector plate (30), which constitutes a relatively narrow current path, rapidly increases, and the bridge (33) begins to fuse. On the other hand, the rupture inducing portion (34) may not undergo any significant change compared to the bridge (33). When an overcurrent continues to flow, the bridge (33) is completely melted, and the electrical connection between the central portion (32) and the peripheral portion (31) of the first collector plate (30) is broken, and the current between the first electrode terminal (17) and the first electrode (21) of the electrode assembly (20) is cut off.

[0174] According to an embodiment, in order to prevent the fusing function of the bridge (33) from being affected by the fracture-inducing portion (34), a virtual fracture line surrounding the terminal junction (320) is set in a closed loop shape, and an area where this virtual fracture-inducing portion is formed is arranged in an area forming a closed loop in a member constituting the central portion of the first collector plate. Then, even if a fracture-inducing portion (34) is formed along the virtual fracture-inducing portion, in which the thickness of the member becomes thinner, the current resistance can be suppressed from increasing in the area, so that the fracture-inducing portion (34) does not affect the fusing function of the bridge (33).

[0175] Meanwhile, as the pressure inside the can (10) increases significantly, the first end wall (12) bulges outward in the axial direction as illustrated in Fig. 15. In particular, the central portion of the first end wall (12) where the first electrode terminal (17) is installed is offset the furthest outward in the axial direction. Accordingly, the terminal joint (320) of the first collector plate (30) joined to the first electrode terminal (17) is also offset outward in the axial direction.

[0176] In contrast, since the peripheral portion (31) of the first collector plate (30) is fixed to the electrode tab (27) that is bent radially by the first electrode junction (310), the bridge (33) of the first collector plate (30) strongly pulls the edge of the central portion (32) radially outward. The force that pulls the edge of the central portion (32) radially outward from the terminal junction (320) gradually increases as the internal pressure of the can (10) increases.

[0177] When the tensile force becomes greater than the yield strength of the fracture-inducing portion (34), the fracture-inducing portion (34) is eventually fractured as illustrated in Fig. 16. Accordingly, the electrical connection between the portion of the central portion (32) of the first collector plate (30) where the terminal connection portion (320) is provided and the edge of the central portion (32) is broken, and the current between the first electrode terminal (17) and the first electrode (21) of the electrode assembly (20) is cut off.

[0178] The above bridge (33) has sufficient strength to withstand tensile force acting in the radial direction. In addition, the bridge (33) extends radially with respect to the terminal joint (320) and also extends in a mutually opposite manner, so that the tensile force is not dispersed due to the bridge (33). That is, according to the embodiment, the influence of the bridge (33) on the fracture inducing action of the fracture inducing portion (34) can be minimized.

[0179] For reference, in order to lower the yield strength of the above-mentioned fracture-inducing portion (34), it is preferable that the above-mentioned fracture-inducing portion (34) be positioned as close as possible to the terminal joint portion (320).

[0180] The above battery cell (72) can be accommodated in a pack housing (71) of a battery pack (70) as illustrated in FIG. 17. The battery pack (70) may be configured using a battery module, which is an intermediate form of assembly, or the battery pack (70) may be configured directly without a battery module as illustrated.

[0181] Since the battery cell (72) described above has a large volume in itself, there is no particular difficulty in implementing a battery pack (70) even without using an intermediate structure called a battery module. Furthermore, the battery cell (72) has low internal resistance and a higher energy density. Accordingly, the energy density of a battery pack (70) equipped with the battery cell (72) can be implemented even higher.

[0182] A battery pack (70) with such a high energy density can store the same amount of energy while reducing its volume and weight. Therefore, when a battery pack (70) equipped with such battery cells (72) is installed in a vehicle, such as an automobile (80) that uses electricity as its energy source, as illustrated in FIG. 10, the vehicle's mileage relative to its energy consumption can be further increased.

[0183] 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.

[0184] 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 current collector that electrically connects the electrode terminal provided in the housing and the electrode of the electrode assembly accommodated in the housing. A central portion having a terminal connection portion that is joined to the electrode terminal so as to be electrically connected to the electrode terminal; A peripheral portion spaced apart from the radial outer side of the central portion, surrounding the central portion, and electrically connected to the electrode; and A bridge extending longitudinally between the central portion and the peripheral portion in a radial direction to connect the central portion and the peripheral portion, and electrically connecting the central portion and the peripheral portion; A current collector plate having a fracture-inducing portion extending circumferentially to surround the terminal joint portion in the central portion.

2. In claim 1, the thickness of the fracture-inducing portion is thinner than the thickness of the central portion on the radially outer and inner sides thereof.

3. In claim 1, the tensile strength of the fracture-inducing portion measured in the radial direction is lower than the tensile strength of the central portion on the outer and inner sides in the radial direction.

4. In claim 1, the fracture-inducing portion is a current collector plate that extends in an open loop or closed loop shape along an imaginary fracture line surrounding the terminal joint.

5. In claim 1, the fracture-inducing portion is a current collector plate that extends continuously or discretely along an imaginary fracture line surrounding the terminal joint.

6. In any one of claims 1 to 5, the bridge has a predetermined width and extends in the longitudinal direction, A current collector plate, wherein the longitudinal first end of the bridge is connected to the peripheral portion and the longitudinal second end of the bridge is connected to the central portion.

7. In any one of claims 1 to 5, the bridge extends radially, A current collector plate, wherein the radially inner end of the bridge is connected to the central portion, and the radially outer end of the bridge is connected to the peripheral portion.

8. A collector plate according to any one of claims 1 to 5, wherein the bridges are arranged in a plurality of spaced apart configurations along the circumferential direction.

9. A side wall extending along the axis and surrounding the internal space in the circumferential direction, A first end wall connected to the axial first end of the side wall and extending radially to cover the internal space; A can having a second end wall connected to the second axial end of the side wall opposite the first end and extending radially to cover the internal space; An electrode assembly having a first electrode and a second electrode and accommodated in the internal space; A first electrode terminal installed through the first end wall so as to be electrically insulated from the first end wall and electrically connected to the first electrode; and A current collector plate according to any one of claims 1 to 5, wherein at least a portion of the peripheral portion is electrically connected to the first electrode by being joined, and at least a portion of the central portion is electrically connected to the first electrode terminal by being joined, The first end wall is a battery cell that shields and partitions the internal space and the external space of the can.

10. A battery cell according to claim 9, wherein the average thickness of the first end wall is thinner than the average thickness of the second end wall.

11. A battery cell according to claim 9, wherein the bulging resistance of the first end wall is smaller than the bulging resistance of the second end wall.

12. In claim 9, a battery cell in which the radius of curvature of the side wall with respect to the central axis of the internal space is smaller than the average radius of curvature of the first end wall with respect to a center existing on an imaginary axis extending along the axial direction of the central axis.

13. A battery cell according to claim 9, wherein either the first end wall or the second end wall is monolithically connected to the side wall.

14. A battery cell according to claim 13, wherein the first end wall is connected to the side wall in a monolithic manner.

15. A battery cell according to claim 9, wherein at least one of the first end wall and the second end wall is connected to the side wall.

16. A battery cell according to claim 15, wherein the second end wall is connected to the side wall.

17. A battery cell according to claim 9, wherein one of the first end wall and the second end wall includes a vent notch portion formed to have a reduced thickness and extending in the circumferential direction.

18. In claim 9, the electrode assembly has a structure in which a separator is interposed between the first electrode and the second electrode and is wound around a core hollow portion extending in the axial direction. The electrode tab of the first electrode is arranged at the axial first end of the electrode assembly, The periphery of the above current collector plate is a battery cell joined to the above electrode tab.

19. In claim 18, the electrode tab is provided such that the current collector of the first electrode, to which the active material is not applied, is bent radially from the axial first end of the electrode assembly, A battery cell, wherein the surface of the bent electrode tab facing the axial outer side is in contact with the axial inner surface of the peripheral portion of the current collector plate.

20. A battery pack comprising the battery cell of claim 9 and a pack case containing the battery cell.

21. A vehicle equipped with the battery pack of claim 20 and driven by power from the battery pack.

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