Battery cell, battery pack comprising same, and vehicle

Abstract

A battery module according to the present invention comprises: an electrode assembly having a winding axis about which a first electrode, a second electrode, and a separator interposed therebetween are wound; a battery housing, which accommodates the electrode assembly, is electrically connected to the second electrode, and has a closed portion having a through-hole; an electrode terminal which passes through the through-hole so as not to make contact with the inner wall of the through-hole and which is electrically connected to the first electrode; and a terminal gasket interposed between the electrode terminal and the through-hole, wherein the electrode terminal has a stepped portion at a contact interface facing the outer surface of the closed portion and making contact with the terminal gasket.

Description

Battery cells, battery packs including the same, and automobiles

[0001] The present invention relates to a battery cell, and more specifically, to a battery cell capable of actively inducing an electrical short circuit when a thermal event, such as thermal runaway, occurs in the battery cell, a battery pack including the same, and an automobile.

[0002] This application is a priority application for Korean Patent Application No. 10-2024-0195746 filed on December 24, 2024, and all contents disclosed in the specification and drawings of said application are incorporated into this application by reference.

[0003] Secondary batteries are attracting attention as a new energy source for improving eco-friendliness and energy efficiency, as they have the primary advantage of being able to drastically reduce the use of fossil fuels, as well as the advantage of not generating any by-products from the use of energy.

[0004] Cylindrical, prismatic, and pouch-type battery cells are widely known as types of secondary batteries. In the case of a cylindrical battery cell, an insulating separator is placed between the positive and negative electrodes and wound to form a jellyroll-shaped electrode assembly, which is then inserted into a housing along with an electrolyte to constitute the battery. Additionally, strip-shaped electrode tabs can be connected to the uninsulated portions of the positive and negative electrodes, and these electrode tabs electrically connect the electrode assembly with the externally exposed electrode terminals. For reference, the positive electrode terminal is the cap of the seal that seals the opening of the housing, and the negative electrode terminal is the housing.

[0005] However, conventional cylindrical batteries having such a structure had the problem that current was concentrated in the strip-shaped electrode tabs connected to the positive electrode unoccupied part and / or the negative electrode unoccupied part, resulting in high resistance, excessive heat generation, and poor current collection efficiency.

[0006] For small cylindrical batteries with 1865 or 2170 form factors, resistance and heat generation are not major issues. However, if the form factor is increased to apply cylindrical batteries to electric vehicles, a problem may arise where the cylindrical battery catches fire as a large amount of heat is generated around the electrode tabs during fast charging.

[0007] To solve these problems, a cylindrical battery (so-called tab-less cylindrical battery) is proposed that has a structure with improved current collection efficiency by designing a positive electrode-free section and a negative electrode-free section to be located at the top and bottom, respectively, of a jellyroll-type electrode assembly, and welding a current collection plate to these non-parts.

[0008] Meanwhile, a conventional tapless cylindrical battery cell, as disclosed in Korean Published Patent No. 10-2024-0059520, includes a battery can functioning as a first electrode and a bottom member of the battery can as a second electrode. A first electrode terminal is fitted into a hole provided in the bottom member of the battery can. The first electrode terminal is electrically insulated from the bottom member of the battery can by riveting it to the bottom member with a gasket interposed therebetween. The cylindrical battery cells can be connected in series and / or in parallel via a busbar to form a battery pack and used as a power source for electric vehicles, etc. When a problem such as a thermal event occurs in any one of the built-in battery cells in the battery pack, it has a thermal or electrical adverse effect on the other battery cells. Therefore, at this time, for example, it is advantageous to prevent or delay chain ignition between battery cells by causing an overcurrent to flow momentarily through the busbar connected to the battery cell where the thermal event occurred, thereby causing the busbar to fuse and interrupting the flow of current between the battery cells. However, in the case of a positive terminal with a riveting structure, when the battery cell explodes, the positive terminal and the battery can, which is the negative terminal, do not come into sufficient contact, making it difficult to induce an electrical short circuit of the battery cell. Consequently, there is an aspect where it is difficult to quickly fuse the busbar.

[0009] The present invention was devised in consideration of the aforementioned problems, and has one objective of providing a battery cell equipped with an electrode terminal of a new structure that can effectively induce contact between the battery housing and the electrode terminal when deformation occurs in the battery housing due to heat and increased internal pressure.

[0010] The technical problems that the present invention aims to solve are not limited to those described above, and other unmentioned problems will be clearly understood by those skilled in the art from the description of the invention below.

[0011] According to the present invention, a battery cell may be provided comprising: an electrode assembly in which a first electrode and a second electrode and a separator interposed between them are wound around a winding axis; a battery housing that accommodates the electrode assembly and is electrically connected to the second electrode and has a closed portion having a through hole formed therein; an electrode terminal that passes through the through hole and is electrically connected to the first electrode so as not to contact the inner wall of the through hole; and a terminal gasket interposed between the electrode terminal and the through hole, wherein the electrode terminal has a stepped portion on a contact interface facing the outer surface of the closed portion and in contact with the terminal gasket.

[0012] The above step portion may include a first layer portion extending parallel to the outer surface of the closure portion; and a second layer portion located radially inward from the first layer portion and having a shorter shortest distance to the outer surface of the closure portion than the first layer portion.

[0013] The terminal gasket may be provided to have a minimum thickness between the second layer and the outer surface of the closure portion facing each other.

[0014] The above step portion may further include a projection protruding toward the outer surface of the closure portion in the above second layer portion.

[0015] The above-mentioned step portion may be provided at a first position where a virtual line extending vertically from the end of the closure portion forming the inner wall of the through hole meets the contact interface, or at a position radially outward from the first position.

[0016] The above terminal gasket may be made of an electrical insulating material of a different material having a relatively different melting point.

[0017] The terminal gasket may include a lower layer in contact with the inner surface of the closure; and an upper layer having a lower melting point than the lower layer and in contact with the outer surface of the closure and the end of the closure.

[0018] The electrode terminal may include: a body portion inserted into the through hole; an outer flange portion extending radially from a first side of the body portion and pressing the terminal gasket against the outer surface of the closure portion; and an inner flange portion extending radially from a second side of the body portion and pressing the terminal gasket against the inner surface of the closure portion.

[0019] It includes a first current collector plate attached to one side of the electrode assembly to contact a first non-contact portion extending from the first electrode, and the electrode terminal may include a flat surface provided to make face-to-face contact with the first current collector plate on the body portion.

[0020] The terminal gasket may include: an outer gasket interposed between the outer flange portion and the outer surface of the closing portion of the battery housing; an inner gasket interposed between the inner flange portion and the inner surface of the closing portion of the battery housing; and an intermediate gasket interposed between the body portion and the through hole and connecting the outer gasket and the inner gasket.

[0021] The battery housing may include a cylindrical shape, a side wall portion extending in the axial direction; a closing portion connected to one end of the side wall portion and extending in the radial direction; and an open end provided at the other end of the side wall portion, and a housing lid covering the open end of the battery housing.

[0022] The electrode assembly may be accommodated inside the battery housing such that a second non-existent portion extending from the second electrode faces the open end.

[0023] It includes a second current collector plate disposed between the electrode assembly and the housing lead inside the battery housing and in contact with the second non-removable portion, and at least one side of the second current collector plate may be welded to the battery housing or the housing lead.

[0024] According to another aspect of the present invention, a battery pack comprising at least one of the above-described battery cells may be provided.

[0025] According to another aspect of the present invention, a vehicle comprising the battery pack may be provided.

[0026] According to one aspect of the present invention, a battery cell having an electrode terminal of a novel structure that can effectively induce contact between the battery housing and the electrode terminal when deformation occurs in the battery housing due to heat and increased internal pressure may be provided.

[0027] The effects obtainable through the present invention are not limited to those described above, and other unmentioned technical effects will be clearly understood by a person skilled in the art from the description of the invention below.

[0028] FIG. 1 is a perspective view of a battery cell according to one embodiment of the present invention.

[0029] FIG. 2 is a schematic diagram illustrating the main components of a battery cell according to an embodiment of the present invention.

[0030] Figure 3 is a cutaway perspective view of the battery cell of Figure 1.

[0031] Figure 4 is a cross-sectional view of the battery cell of Figure 1.

[0032] Figure 5 is an enlarged view of the electrode terminal portion in Figure 3.

[0033] FIGS. 6 and FIGS. 7 are process diagrams for explaining a process of assembling electrode terminals to a battery housing according to an embodiment of the present invention.

[0034] Figure 8 is an enlarged view of the electrode terminal portion of Figure 7.

[0035] Figure 9 is a diagram showing an example of contact between the end of the closure and the electrode terminal when the battery housing is deformed by heat and pressure.

[0036] FIG. 10 is a cross-sectional view showing a portion of an electrode terminal and a terminal gasket coupled to a battery housing according to another embodiment of the present invention.

[0037] FIG. 11 is a cross-sectional view showing a portion of an electrode terminal and a terminal gasket coupled to a battery housing according to another embodiment of the present invention.

[0038] FIG. 12 is a schematic diagram illustrating a battery pack according to the present invention.

[0039] Figure 13 is a diagram showing battery cells connected to the busbar in the battery pack of Figure 12.

[0040] FIG. 14 is a drawing for explaining a vehicle including the battery pack of FIG. 12.

[0041] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention. Accordingly, the embodiments described in this specification and the configurations illustrated in the drawings are merely some of the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention; therefore, it should be understood that various equivalents and modifications capable of replacing them may exist at the time of filing this application.

[0042] Additionally, to aid in understanding the invention, the attached drawings are not drawn to actual scale, and the dimensions of some components may be exaggerated. Furthermore, the same reference numerals may be assigned to identical components in different embodiments.

[0043] Meanwhile, although terms indicating directions such as up, down, left, right, front, and back may be used in the present invention, these terms are used merely for convenience of explanation and may vary depending on the position of the object or the position of the observer, as is obvious to those skilled in the art of the present invention.

[0044] In the following description, the battery cell is provided in a cylindrical shape that accommodates a jelly-roll type electrode assembly inside. In the specification of the description, the direction following the height direction of the battery cell is referred to as the axial direction. The direction surrounding an imaginary centerline passing through the center of the battery cell along the height direction is referred to as the circumferential direction or perimeter direction. The direction approaching or moving away from the centerline is referred to as the radial direction. In particular, the direction approaching the centerline is referred to as the centripetal direction, and the direction moving away from the centerline is referred to as the centrifugal direction.

[0045] FIG. 1 is a perspective view of a battery cell according to an embodiment of the present invention, FIG. 2 is a schematic diagram illustrating the main components of a battery cell according to an embodiment of the present invention, FIG. 3 is a cutaway perspective view of the battery cell of FIG. 1, and FIG. 4 is a cross-sectional view of the battery cell of FIG. 1.

[0046] Referring to these drawings, a battery cell (10) according to one embodiment of the present invention includes an electrode assembly (100), a battery housing (200), an electrode terminal (300), and a terminal gasket (400).

[0047] The electrode assembly (100) may include a first electrode, a second electrode having a polarity opposite to that of the first electrode, and a separator interposed between the first electrode and the second electrode. The first electrode may be a positive electrode and the second electrode may be a negative electrode. Conversely, the first electrode may be a negative electrode and the second electrode may be a positive electrode. The separator may be configured to cover the inner wall surface of the winding center hole of the electrode assembly (100). The separator may be configured to cover at least partially the outer circumference of the electrode assembly (100).

[0048] The above electrode assembly (100) may be, for example, a jelly roll type electrode assembly (100) formed by winding a laminate including an anode, a cathode, and a separator.

[0049] The first electrode comprises a first electrode current collector and a first electrode active material applied on one or both sides of the first electrode current collector. At one end of the first electrode in the width direction (Z direction), there exists a non-exposed portion where the first electrode active material is not applied. That is, the first electrode includes a non-exposed portion along the winding direction where the active material is not coated at the long end and is exposed to the outside of the separator. The non-exposed portion functioning as an electrode tab of the first electrode is hereinafter referred to as the first non-exposed portion (111). The first non-exposed portion (111) is provided on the upper side in the height direction (Z direction) of the electrode assembly (100) housed within the battery housing (200). That is, the first electrode includes a first non-exposed portion (111) where the active material layer is not coated at the long end and is exposed to the outside of the separator, and at least a portion of the first non-exposed portion (111) is used as an electrode tab itself. The first non-removable part (111) above may be, for example, an anode tab.

[0050] At least a portion of the first bare portion (111) may include a plurality of segments divided along the winding direction of the electrode assembly (100). In this case, the plurality of segments may be bent along the radial direction of the electrode assembly (100). The bent plurality of segments may be overlapped in multiple layers. A first current collector plate (101) may be disposed on the upper portion of the first bare portion (111). For example, the first bare portion (111) and the first current collector plate (101) may be in contact, and at least one part of the contact may be welded.

[0051] The second electrode comprises a second electrode current collector and a second electrode active material coated on one or both sides of the second electrode current collector. At the other end of the second electrode current collector in the width direction (Z direction), there exists a non-coated portion where the second electrode active material is not coated. The non-coated portion functioning as an electrode tab of the second electrode is hereinafter referred to as the second non-coated portion (112). The second non-coated portion (112) is located on the lower side of the electrode assembly (100) housed within the battery housing (200) in FIG. 3. That is, the second electrode current collector includes a second non-coated portion (112) that is exposed to the outside of the separator and where the active material layer is not coated at the long end, and at least a portion of the second non-coated portion (112) is used as an electrode tab itself. The second non-coated portion may be, for example, a negative electrode tab.

[0052] At least a portion of the second non-reinforced portion (112) may include a plurality of segments divided along the winding direction of the electrode assembly (100), similar to the first non-reinforced portion (111) described above. In this case, the plurality of segments may be bent along the radial direction of the electrode assembly (100). The bent plurality of segments may be overlapped in multiple layers. A second current collector plate (102) may be disposed on the lower part of the second non-reinforced portion (112). For example, the second non-reinforced portion (112) and the second current collector plate (102) may be connected by welding.

[0053] The battery housing (200) may be configured to accommodate the electrode assembly (100) as a cylindrical receptacle. The battery housing (200) is made of a conductive material, such as metal, for example. The material of the battery housing (200) may be steel, stainless steel, or nickel-plated steel.

[0054] As illustrated in FIGS. 2 to 4, the battery housing (200) may have a cylindrical shape and may include a side wall portion (210) extending in the axial direction (Z direction), a flat closed portion (220) connected to one end in the height direction (Z direction) of the side wall portion (210) and extending in the radial direction, and an open portion (230) provided at the other end in the height direction of the side wall portion (210).

[0055] The side of the above-mentioned side wall portion (210) that is not connected to the above-mentioned closed portion (220) can be defined as the open end (230) of the battery housing (200). The battery housing (200) can be formed by, for example, by forming a metal sheet with nickel plated on the surface of steel using a deep drawing process to integrally form the above-mentioned side wall portion (210) and the above-mentioned closed portion (220), and then forming the above-mentioned open end (230) by trimming the end of the above-mentioned side wall portion (210) located opposite the above-mentioned closed portion (220) with a punch while holding it with a holder.

[0056] The battery housing (200) can accommodate an electrode assembly (100) in its internal space through the open end (230). At this time, the electrode assembly (100) can be accommodated in the battery housing (200) such that, as shown in FIG. 2, the first unoccupied portion (111) faces the closed portion (220) and the second unoccupied portion (112) faces the open end (230). The open end (230) of the battery housing (200) can be covered by a housing lid (500).

[0057] The housing lead (500) may have an electrolyte injection hole (510) in the center. The electrolyte injection hole (510) may be configured to face a cavity (S1) formed in the center of the winding core of the electrode assembly (100). Additionally, the second current collector plate (102) may have a center hole (102a) in the center facing the electrolyte injection hole (510).

[0058] After attaching the housing lid (500) to the open end (230) of the battery housing (200), the electrolyte can be injected into the interior of the battery housing (200) through the electrolyte injection hole (510) and the center hole (102a). The electrolyte injection hole (510) can be closed after the electrolyte injection is completed. For example, the electrolyte injection hole (510) can be sealed with a lead hole cap (520) provided in the form of a disc made of metal material. As an alternative to the present embodiment, the electrolyte injection hole (510) may be sealed by pressing a ball (not shown) into the electrolyte injection hole (510). In this case, welding may be performed or an adhesive may be applied to the contact interface between the ball and the electrolyte injection hole (510).

[0059] The battery housing (200) can be electrically connected to the second electrode of the electrode assembly (100). As shown in FIGS. 3 and 4, the second non-electrical portion (112) extending from the second electrode is arranged to be in contact with the second current collector plate (102), and the second current collector plate (102) is configured to be in contact with the battery housing (200), so that the battery housing (200) can be electrically connected to the second electrode. Accordingly, the battery housing (200) has the same polarity as the second electrode.

[0060] The electrode terminal (300) may be configured to be electrically connected to the first electrode by passing through a through hole formed in the closed portion (220) of the battery housing (200) so as to have the same polarity as the first electrode.

[0061] The electrode terminal (300) is made of a conductive metal material. The electrode terminal (300) may be made of, for example, a 10-series aluminum alloy that is easy to plastically process and has low resistance.

[0062] As illustrated in FIGS. 3 and 4, a first current collector plate (101) may be positioned to contact the upper portion of a first non-contact portion (111), and an electrode terminal (300) may be positioned to contact the upper portion of the first current collector plate (101) by passing through a through hole of the closed portion (220). In this case, the electrode terminal (300) has the same polarity as the first electrode. Such an electrode terminal (300) may be configured to be electrically insulated from a battery housing (200) having a second polarity. For example, the electrode terminal (300) passes through the through hole so as not to come into contact with the inner wall of the through hole, a terminal gasket (400) is interposed between the electrode terminal (300) and the through hole, and an insulator (105) is interposed between the first current collector plate (101) and the closed portion (220) of the battery housing (200), thereby enabling electrical insulation between the electrode terminal (300) and the battery housing (200).

[0063] Referring to FIG. 5, the electrode terminal (300) includes a body portion (310), an outer flange portion (320), and an inner flange portion (330).

[0064] The above body portion (310) is configured such that at least a portion is inserted into the through hole of the closure portion (220). For example, the upper portion of the body portion (310) is located outside the closure portion (220), the lower portion is located inside the closure portion (220), and the portion between the upper portion and the lower portion is positioned in the through hole.

[0065] The above body portion (310) includes a welded portion at the lower portion. The welded portion is a part welded to the first collector plate (101) and may preferably be formed as a flat surface (331). As will be described later, the welded portion may be an area that is not deformed by plastic processing.

[0066] The outer flange portion (320) may be extended radially from the first side of the body portion (310) and arranged parallel to the outer surface of the closure portion (220). Here, the first side may be defined as the upper part of the body portion (310) in FIG. 5. The terminal gasket (400) portion interposed between the outer flange portion (320) and the outer surface of the closure portion (220) may be compressed by the outer flange portion (320).

[0067] The inner flange portion (330) may be extended radially from the second side of the body portion (310) and positioned to face the inner surface of the closure portion (220). Here, the second side may be defined as the lower end of the body portion (310) in FIG. 5. The terminal gasket portion (400) interposed between the inner flange portion (330) and the inner surface of the closure portion (220) may be compressed by the inner flange portion (330).

[0068] A recess portion (332) may be provided between the inner flange portion (330) and the flat surface (331) of the body portion (310). The recess portion (332) is a groove recessed in the direction of the central axis of the body portion (310). The recess portion (332) may have an asymmetric cross-section. In one example, the asymmetric cross-section may be approximately V-shaped or U-shaped.

[0069] The terminal gasket (400) comprises an outer gasket (410) interposed between the outer flange portion (320) and the outer surface of the closing portion (220) of the battery housing (200), an inner gasket (420) interposed between the inner flange portion (330) and the inner surface of the closing portion (220) of the battery housing (200), and an intermediate gasket (430) interposed between the body portion (310) and the through hole and connecting the outer gasket (410) and the inner gasket (420).

[0070] At least one of the outer gasket (410), the inner gasket (420), and the intermediate gasket (430) may have a thickness that varies depending on the location. Preferably, the thickness of the intermediate gasket (430) may vary depending on the location. For example, the thickness of the intermediate gasket (430) may gradually decrease as it moves toward the outside of the through hole along the axial direction (Z direction), so that it may have a minimum thickness in the terminal gasket (400).

[0071] The above-mentioned external gasket (410) may be exposed to the outside of the outer flange portion (320) of the electrode terminal (300) at least partially. The purpose of exposing the external gasket (410) is to insulate it from the closed portion (220) of the battery housing (200) having polarity opposite to that of the electrode terminal (300). For example, the exposure width (G) of the external gasket (410) may be 0.1 mm to 1 mm. If the exposure width (G) is smaller than 0.1 mm, the electrical insulation between the electrode terminal (300) and the closed portion (220) on a flat surface may be destroyed when high c-rate charging and discharging of 300 A or more occurs. Additionally, if the exposure width (G) is larger than 1 mm, the electrical insulation effect is not further increased, and rather, the contact area of ​​the component (e.g., busbar) used for electrical connection is reduced by reducing the outer surface area of ​​the closed portion (220) used as the negative electrode region.

[0072] In this embodiment, the outer gasket (410), inner gasket (420), and intermediate gasket (430) are integral. However, unlike this embodiment, the outer gasket (410) and the intermediate gasket (430) may be integral, and the inner gasket (420) may be provided separately. Alternatively, the intermediate gasket (430) and the inner gasket (420) may be integral, and the outer gasket (410) may be provided separately.

[0073] The terminal gasket (400) may be made of a polymer resin having insulating and elastic properties. In one example, the terminal gasket (400) may be made of polypropylene, polybutylene terephthalate, polyfluoroethylene, etc., but the present invention is not limited thereto.

[0074] Next, with reference to FIGS. 6 and 7, the assembly structure of the battery housing (200) and the electrode terminal (300) will be briefly described.

[0075] According to an embodiment of the present invention, the assembly structure of the electrode terminal (300) and the battery housing (200) can be formed using a corking jig (not shown) that moves up and down. First, a preform of the electrode terminal (300) is inserted by interposing a terminal gasket (400) into a through hole formed in the closed portion (220) of the battery housing (200). As shown in FIG. 6, the preform refers to the electrode terminal (300) before the corking process is performed.

[0076] Next, a corking jig is inserted into the inner space of the battery housing (200). The corking jig has a structure on the surface facing the preform that corresponds to the final shape of the electrode terminal (300) in order to form the electrode terminal (300) by pressurizing the preform.

[0077] Next, the corking jig is moved toward the preform to pressurize the lower part of the preform, thereby deforming the preform into an electrode terminal (300) riveted into a through hole of the battery housing (200).

[0078] While the shape of the preform is deformed as it is pressed by the corking jig, the outer gasket (410) interposed between the outer flange portion (320) and the outer surface of the closing portion (220) of the battery housing (200) is elastically compressed, and its thickness is reduced. In addition, the intermediate gasket (430) and the inner gasket (420) interposed between the inner wall of the through hole and the preform are elastically compressed and their thickness is reduced as they are deformed by the inner flange portion (330), as shown in FIG. 7.

[0079] Preferably, the terminal gasket (400) is sufficiently compressed so that the desired sealing strength is secured without the preform being physically damaged during the riveting process through a plastic deformation process called corking.

[0080] Preferably, the compression ratio of the terminal gasket (400) may be 30% to 90%. The minimum compression ratio corresponds to the minimum level of compression ratio required to ensure the sealing (sealing) of the electrode terminal (300). The maximum compression ratio corresponds to the maximum level of compression ratio that can be achieved without physically damaging the terminal gasket (400).

[0081] In one example, when the terminal gasket (400) is made of polybutylene terephthalate, it is preferable that the terminal gasket (400) has a compression ratio of 50% or more at the point where it is compressed to a minimum thickness.

[0082] Referring to FIG. 8, the electrode terminal of the battery cell according to the present embodiment has a step portion (340) on the contact interface facing the outer surface of the closure portion (220) and in contact with the terminal gasket (400).

[0083] The purpose of applying the step portion (340) to the electrode terminal (300) is to actively induce an electrical short circuit between the electrode terminal (300) having a first polarity and the battery housing (200) having a second polarity when a thermal event occurs in the battery cell (10), thereby fusing the busbar (20) in the battery pack (1) described later to cut off the electrical connection between the battery cells (10).

[0084]

[0085] For example, the step portion (340) includes a first layer (341) that extends parallel to the outer surface of the closed portion (220) of the battery housing (200), and a second layer (342) that is located radially inward from the first layer (341) and has a shorter shortest distance to the outer surface of the closed portion (220) than from the first layer (341).

[0086] Additionally, the step portion (340) is provided at a first position where a virtual line (CL) extending vertically from the end (220a) of the closing portion (220) forming the inner wall of the through hole meets the contact interface, or at a position radially outward from the first position.

[0087] According to the above configuration, as illustrated in FIG. 9, when a thermal event occurs in the battery cell (10) and the closure (220) swells outward, the possibility of contact between the end (220a) of the closure (220) and the electrode terminal (300) can be increased. For example, when a thermal event occurs in the battery cell (10), at least a portion of the terminal gasket (400) is thermally melted and becomes fluid. And when the battery housing (200) expands, the end (220a) of the closure (220) tilts away from the body portion (310) of the electrode terminal (300). In this case, the terminal gasket (400) is compressed by receiving pressure from the end (220a) of the tilting closure (220), and can move radially outward and radially inward relative to the first position area. If the expansion pressure of the battery housing increases further, the terminal gasket (400) may eventually break and split based on the first position area, and the closed portion may come into contact with the second layer ((342)) of the stepped portion (340).

[0088] For example, the thickness of the terminal gasket (400) region interposed between the outer surface of the closure portion (220) facing the second layer portion (342) of the electrode terminal (300) is provided to be the thinnest than other regions. That is, the terminal gasket (400) has a minimum thickness between the outer surface of the second layer portion (342) and the closure portion (220) facing each other. In this case, the possibility of contact between the electrode terminal (300) and the closure portion (220) of the battery housing (200) can be further increased.

[0089] Meanwhile, an electrode terminal (300) equipped with a stepped portion (340) may be more advantageous in terms of airtightness than an electrode terminal without a stepped portion (340). For example, as in the embodiment of FIGS. 6 and 7, an outer gasket (410) in a terminal gasket (400) is compressed by the outer flange portion (320) of the electrode terminal (300) and is interposed between the outer flange portion (320) and the outer surface of the closure portion (220). At this time, the outer gasket (410) is compressed to correspond to the shape of the stepped portion (340). In this case, the contact area between the electrode terminal (300) and the terminal gasket (400) is increased by the perimeter area of ​​the stepped surface indicated as 'D1' in FIG. 8, thereby increasing the airtightness.

[0090] In this way, according to the configuration of the stepped portion (340) of the electrode terminal (300) according to the present embodiment, the airtightness between the electrode terminal (300) and the through hole of the battery housing (200) in which the electrode terminal (300) is installed is increased, and when a thermal event such as thermal runaway of the battery cell (10) occurs, the possibility of contact between the electrode terminal (300) and the battery housing (200) is increased, so that an electrical short circuit of the battery cell (10) can be easily induced.

[0091] Next, with reference to FIGS. 10 and FIGS. 11, a battery cell according to other embodiments of the present invention will be briefly described.

[0092] Reference numbers identical to those in previous drawings indicate identical components. Duplicate descriptions of identical components will be omitted, and the explanation will focus on the differences from the previously described embodiments.

[0093] FIG. 10 is a cross-sectional view showing a portion of an electrode terminal (300) and a terminal gasket (400) coupled to a battery housing (200) according to another embodiment of the present invention.

[0094] A battery cell (10) according to another embodiment of the present invention differs from the above-described embodiment in the physical properties of the terminal gasket (400), and otherwise has substantially the same configuration.

[0095] A terminal gasket (400) according to another embodiment of the present invention may be provided with an electrical insulating material of a different material having a relatively different melting point.

[0096] Specifically, according to another embodiment of the present invention, the terminal gasket (400) of the battery cell (10) comprises a lower layer (402) and an upper layer (401) having a lower melting point than the lower layer (402). The lower layer (402) refers to an area located inside the battery housing compared to the upper layer (401).

[0097] The lower layer (402) is in contact with the inner surface of the closure (220), and the upper layer (401) has a lower melting point than the lower layer (402) and can be in contact with the outer surface of the closure (220) and the end of the closure.

[0098] For example, as illustrated in FIG. 10, the terminal gasket (400) may be divided into an upper layer (401) and a lower layer (402). The upper layer (401) may include an outer gasket (410) and an upper region of an intermediate gasket (430), and the lower layer (402) may include a lower region of an intermediate gasket (430) and an inner gasket (420).

[0099] The upper layer (401) and the lower layer (402) may be simply laminated, or their entire surface or at least a portion thereof may be bonded together by a binder. Alternatively, the boundary surface between the upper layer (401) and the lower layer (402) may be fused and integrated by heat.

[0100] The upper layer (401) has a lower melting point than the lower layer (402). Specifically, the difference in melting points between the upper layer (401) and the lower layer (402) may be 20°C or more and 90°C or less. The melting point of the upper layer (401) may be 140°C to 180°C, and the melting point of the lower layer (402) may be 210°C to 250°C.

[0101] For example, the upper layer (401) may include a polypropylene-based polymer having a melting point of 140°C to 180°C. The propylene-based polymer means containing 50% by weight or more of a propylene-derived monomer or a polypropylene segment. The upper layer (401) may also contain 80% by weight or more of polypropylene, or 90% by weight or more. Since the melting point of the upper layer (401) is lower than that of the lower layer (402), as previously mentioned, it is easy to cause contact between the battery housing (200) and the electrode terminal (300) during thermal runaway of the battery cell (10).

[0102] In the present invention, the lower layer (402) may include a polybutylene terephthalate-based polymer having a melting point of 210°C to 250°C. The polybutylene terephthalate-based polymer may include 50% by weight or more of polybutylene terephthalate segments. In a specific embodiment, the lower layer (402) may include 80% by weight or more of polybutylene terephthalate, or 90% by weight or more. When the lower layer (402) of the terminal gasket (400) includes the polybutylene terephthalate-based polymer, it is effective in increasing the high sealing power of the terminal gasket (400) and preventing electrolyte leakage.

[0103] With reference to FIG. 11, a battery cell according to another embodiment of the present invention will be briefly described.

[0104] According to another embodiment of the present invention, the stepped portion (340A) of the electrode terminal (300) of the battery cell includes a projection (343) protruding toward the outer surface of the closed portion (220) in the second layer portion (342).

[0105] In this case, when the battery housing (200) expands due to an increase in internal pressure of the battery cell (10), the possibility of contact between the end (220a) of the closure part (220) and the electrode terminal (300) increases further. In particular, the thickness of the terminal gasket (400) interposed between the projection (343) and the end (220a) of the closure part (220) forms a minimum thickness section that is the minimum thickness section compared to other sections of the terminal gasket (400). In this case, when the battery housing (200) expands, the minimum thickness section is broken by the pressure of the closure part (220), and the terminal gasket (400) separates and moves to both sides based on the minimum thickness section, allowing the projection of the electrode terminal (300) and the end (220a) of the closure part (220) to come into contact.

[0106] FIG. 12 is a schematic diagram illustrating a battery pack according to the present invention, and FIG. 13 is a diagram showing battery cells (10) connected to a busbar in the battery pack of FIG. 12.

[0107] As illustrated in FIG. 12, a battery pack (1) according to one embodiment of the present invention may include the aforementioned battery cells (10), a bus bar (20) that electrically connects the battery cells (10), and a pack housing (2) for accommodating the battery cells (10).

[0108] In the above battery cell (10), the electrode terminal (300) may have a positive polarity, and the outer surface of the closed portion (220) of the battery housing (200) may have a negative polarity, and the opposite case is also possible.

[0109] Multiple battery cells (10) can be arranged in multiple columns and rows. As another example, to maximize space efficiency, the battery cells (10) can be arranged to form an equilateral triangle when the centers of the electrode terminals (300) are connected to each other by a virtual line.

[0110] The busbar (20) can be positioned above a plurality of battery cells (10), more preferably between adjacent columns. Alternatively, the busbar (20) can be positioned between adjacent rows.

[0111] The busbar (20) connects battery cells (10) arranged in the same row in parallel with each other and connects battery cells (10) arranged in two adjacent rows in series with each other.

[0112] First connection tabs (21) extending from one side of the bus bar (20) protrude toward the electrode terminal (300) of each battery cell (10) and can be electrically connected to the electrode terminal (300). Electrical connection with the electrode terminal (300) can be achieved through laser welding, ultrasonic welding, etc. Second connection tabs (22) extending from the other side of the bus bar (20) protrude toward the outer surface of the closure (220) of the battery housing (200) of each battery cell (10) and can be electrically connected to the outer surface of the closure (220). Electrical connection with the outer surface of the closure (220) can be achieved through laser welding, ultrasonic welding, etc.

[0113] As described above, the battery cell (10) according to the present invention can easily induce an electrical short circuit on its own when a thermal event occurs. Therefore, in a battery pack (1) including battery cells (10) according to the present invention, when a thermal runaway occurs in any one battery cell (10), the first connection tab (21) or the second connection tab (22) connected thereto may be fused by the instantaneous overcurrent generated in said battery cell (10). Consequently, the electrical connection between said one battery cell (10) and other battery cells (10) may be cut off. In this way, electrical disconnection between battery cells (10) when a battery cell (10) ignites can be advantageous in delaying chain ignition or preventing explosion.

[0114] Meanwhile, the battery pack (1) may be configured using a battery module, which is an intermediate form of assembly, or the battery pack (1) may be configured directly without a battery module as illustrated. As in this embodiment, the battery pack (1) in which the battery cells are directly housed in the housing (2) of the battery pack (1) without configuring a battery module can be implemented with a higher energy density.

[0115] A battery pack (1) with such increased energy density can store the same amount of energy while reducing its volume and weight. Therefore, if a battery pack (1) with such battery cells (10) is installed in a vehicle such as a car (V) that uses electricity as an energy source, as shown in FIG. 14, the vehicle's mileage relative to energy can be further increased.

[0116] The automobile (V) according to the present invention includes a battery pack (1) according to the present invention. The automobile (V) may be configured to operate by receiving power from the battery pack (1) according to the present invention.

[0117] The embodiments described above should be understood as exemplary in all respects and not limiting, and the scope of the invention will be defined by the claims set forth below rather than by the detailed description above. Furthermore, the meaning and scope of the claims set forth below, as well as all modifications and variations derived from equivalents thereof, should be interpreted as being included within the scope of the invention.

[0118] Although the present invention has been described above with reference to the illustrated drawings, the present invention is not limited by the embodiments and drawings disclosed in this specification, and it is obvious that various modifications can be made by a person skilled in the art within the scope of the technical concept of the present invention. Furthermore, even if the effects of the configuration according to the present invention were not explicitly described while describing the embodiments of the present invention above, it is natural to acknowledge that the effects predictable by said configuration should also be recognized.

Claims

1. An electrode assembly comprising a first electrode and a second electrode and a separator interposed between them, wound around a winding axis; A battery housing that accommodates the electrode assembly and is electrically connected to the second electrode, and has a closed portion having a through hole formed therein; An electrode terminal passing through the through hole so as not to come into contact with the inner wall of the through hole and electrically connected to the first electrode; and It includes a terminal gasket interposed between the electrode terminal and the through hole, The above electrode terminal is, A battery cell characterized by having a stepped portion on the contact interface facing the outer surface of the above-mentioned closure portion and in contact with the above-mentioned terminal gasket.

2. In Paragraph 1, The above step portion is, A first layer extending parallel to the outer surface of the above-mentioned closure; and A battery cell characterized by including a second layer located radially inward from the first layer and having a shorter shortest distance to the outer surface of the closure than the first layer.

3. In Paragraph 2, A battery cell characterized in that the terminal gasket has a minimum thickness between the outer surface of the second layer and the closure portion facing each other.

4. In Paragraph 2, The above step portion is, A battery cell characterized by further including a projection protruding toward the outer surface of the closure portion in the second layer portion.

5. In Paragraph 1, A battery cell characterized in that the above-mentioned step portion is provided at a first position where a virtual line extending vertically from the end of the closure portion forming the inner wall of the through hole meets the contact interface, or at a position radially outward from the first position.

6. In Paragraph 1, A battery cell characterized in that the terminal gasket is made of an electrical insulating material of a different material having a relatively different melting point.

7. In Paragraph 1, The above terminal gasket is, A lower layer in contact with the inner surface of the above-mentioned closure; and A battery cell characterized by including an upper layer having a lower melting point than the lower layer and contacting the outer surface of the closure and the end of the closure.

8. In Paragraph 1, The above electrode terminal is, A body part inserted into the above-mentioned through hole; An outer flange portion extending radially from the first side of the body portion and pressing the terminal gasket against the outer surface of the closure portion; and A battery cell comprising an inner flange portion that extends radially from the second side of the body portion and presses the terminal gasket against the inner surface of the closure portion.

9. In Paragraph 8, It includes a first current collector plate attached to one side of the electrode assembly to contact a first non-retaining portion extending from the first electrode, and A battery cell characterized in that the electrode terminal includes a flat surface provided to make face-to-face contact with the first current collector plate in the body portion.

10. In Paragraph 8, The above terminal gasket is, An external gasket interposed between the outer flange portion and the outer surface of the closed portion of the battery housing; An internal gasket interposed between the inner flange portion and the inner surface of the closure portion of the battery housing; and A battery cell characterized by including an intermediate gasket interposed between the body portion and the through hole and connecting the outer gasket and the inner gasket.

11. In Paragraph 1, The battery housing has a cylindrical shape and comprises: a side wall portion extending in the axial direction; a closing portion connected to one end of the side wall portion and extending in the radial direction; and an open end provided at the other end of the side wall portion. A battery cell characterized by including a housing lid that covers the open end of the battery housing.

12. In Paragraph 11, A battery cell characterized in that the electrode assembly is accommodated inside the battery housing such that a second non-existent portion extending from the second electrode faces the open end.

13. In Paragraph 12, It includes a second current collector plate disposed between the electrode assembly and the housing lead inside the battery housing and in contact with the second non-removable portion, A battery cell characterized in that at least one side of the second current collector plate is welded to the battery housing or the housing lead.

14. A battery pack characterized by including at least one battery cell described in any one of claims 1 to 13.

15. An automobile characterized by including a battery pack according to paragraph 14.

Images