Battery cell, and battery pack and vehicle comprising same

Abstract

A battery cell, according to the present invention, comprises: an electrode assembly in which a first electrode, a second electrode, and a separator interposed therebetween are wound around a winding axis; a battery housing provided with an open end portion so that the electrode assembly is inserted therein; and a housing lid coupled to the open end portion of the battery housing, wherein the open end portion has an inclined portion formed so as to be inclined from an inner surface toward an outer surface so as to guide the press-fitting of the housing lid, the housing lid comprises a lid outer portion having an abutting surface coming into contact with the open end portion, and the abutting surface may be configured so as to extend longer in the axial direction of the battery housing than the inclined portion.

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 having an improved assembly and bonding structure of a battery housing and a housing lead, a battery pack including said battery cell, and an automobile.

[0002] This application is a priority application for Korean Patent Application No. 10-2024-0182638 filed on December 10, 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, conventional cylindrical battery cells, as disclosed in Korean Published Patent No. 10-2024-0069584, include a beading section and a crimping section for assembly between a current collector, a battery housing, and a housing cover. The beading section has a shape that is pressed inward in the area between an opening formed on one side of the battery housing and a receiving section that accommodates an electrode assembly. The crimping section has a shape that extends and is bent from the beading section to wrap around the outer perimeter of the housing cover. A cylindrical battery having the beading section and the crimping section has the advantage of facilitating the fixation of the negative electrode current collector and providing excellent airtightness between the battery housing and the housing cover. However, the process for forming the beading section and the crimping section is not a simple process that requires precision. Consequently, product defects frequently occur during the beading or crimping fixation process, which can lead to a decrease in production yield. Furthermore, it has been pointed out that a cylindrical battery having the beading section and the crimping section is disadvantageous in terms of energy density. Accordingly, it is necessary to eliminate the beading part and the clamping part in the battery housing and to improve the sealing structure to be simpler.

[0009] Meanwhile, a process for sealing a battery housing that omits the beading and crimping sections and assembles the inner side of the open end of the battery housing by welding the outer side of the housing cover has recently gained prominence. However, since the welding quality in the above process depends on the precise assembly between the open end of the battery housing and the housing cover, a method to reduce the assembly tolerance between the open end of the battery housing and the housing cover is required.

[0010] The present invention was devised in consideration of the aforementioned problems and has one objective of providing a battery cell capable of improving the assembly between a battery housing and a housing lead.

[0011] According to another aspect of the present invention, one objective is to provide a battery cell capable of improving weldability between a battery housing and a housing lead, and between a battery housing and a current collector plate.

[0012] 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.

[0013] According to the present invention, 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 having an open end to allow the electrode assembly to be inserted therein; and a housing lead coupled to the open end of the battery housing, wherein the open end is formed inclined from an inner surface toward an outer surface to guide an interference fit of the housing lead, and the housing lead includes a lead outer portion having a butting surface that contacts the open end, and the butting surface may be provided as a battery cell that extends longer in the axial direction of the battery housing than the inclined portion.

[0014] The above-mentioned open end comprises: a first vertical portion forming a portion of the inner surface; an inclined portion forming the remaining portion of the inner surface and extending obliquely in the direction of the outer surface from the end of the first vertical portion; a horizontal portion extending horizontally in the direction of the outer surface from the end of the inclined portion; and a second vertical portion connected to the end of the horizontal portion and forming the outer surface, and the housing lead may have an outer portion of the lead that contacts at least a portion of the inner surface of the open end.

[0015] The above-mentioned buttock surface may include a first buttock surface arranged to be spaced apart from the inclined portion and having a predetermined gap between it and the inclined portion; and a second buttock surface arranged to be in face contact with the first vertical portion.

[0016] A weld bead may be formed in the predetermined gap provided between the inclined portion and the first butting surface.

[0017] As another example, the abutting surface may include a first abutting surface inclined to make face contact with the inclined portion; and a second abutting surface provided to make face contact with the first vertical portion.

[0018] As another example, the abutting surface may include a first abutting surface inclined to make face contact with the inclined portion; and a second abutting surface extending at the same angle as the first abutting surface and inserted into the interior of the battery housing.

[0019] The above-mentioned inclined portion may be configured such that the slope increases as it moves toward the direction in which the outer part of the lead is inserted.

[0020] The height of the above-mentioned inclined portion may be 0.1mm to 0.4mm.

[0021] The ratio of the height of the inclined portion and the length of the abutting surface of the outer side of the lead may be 1:2.5 to 1:10.

[0022] The battery housing may include a first current collector plate electrically connected to the first electrode inside the battery housing, wherein the first current collector plate may include: a central portion of the plate that contacts a first non-retaining portion extending from the first electrode; an outer portion of the plate that is offset axially from the central portion of the plate, spaced apart from the first non-retaining portion, and extends centrifugally to contact a first vertical portion of the open end; and an edge bend portion that extends obliquely toward the outer portion of the lead from the end of the outer portion of the plate that contacts the first vertical portion.

[0023] The weld filler is further included in the excess space enclosed by the first vertical section, the edge bending section, and the lead outer section, and the first vertical section, the edge bending section, and the lead outer section can be integrally welded by the weld filler.

[0024] The above welding filler can be provided in a shape that fits into the above excess space.

[0025] The above welding filler may be provided with a metal material having a lower melting point than the battery housing, the first current collector plate, and the housing lead.

[0026] The above welding filler may be configured to be located inside the battery housing to limit the depth to which the housing lead is inserted into the battery housing.

[0027] The battery housing includes a first current collector plate disposed between the electrode assembly and the housing lead inside the battery housing and electrically connected to the first electrode, wherein the housing lead has an electrolyte injection hole in the center and the first current collector plate has a center hole facing the electrolyte injection hole in the center, and the center hole may be disposed to face a cavity in the center of the winding core provided in the electrode assembly in the axial direction.

[0028] The outer part of the above lead can be provided in a 'U' shape.

[0029] The housing lead may include a lead center portion connected to the outer portion of the lead and configured to make direct axial contact with a first non-removable portion extending from the first electrode.

[0030] As another example, the housing lead may include: a lead core portion that is convexly provided at the center of the housing lead and extends from the first electrode and is spaced axially apart from the first electrode; and an electrode contact portion configured to make direct axial contact with the first electrode between the lead core portion and the outer portion of the lead.

[0031] The electrode contact portion may be configured to be divided into three regions along the circumferential direction of the housing lead.

[0032] The lead core portion is provided with an electrolyte injection hole formed through in the axial direction, and the housing lead further includes a plug cap covering the electrolyte injection hole, and the plug cap may include a cap outer portion facing the surface of the lead core portion at the outside of the electrolyte injection hole, and a cap central portion provided in a shape protruding more than the cap outer portion so as to be pressed into the electrolyte injection hole.

[0033] The outer edge of the cap is spaced from the electrolyte injection hole by 1.5 mm to 3.5 mm, and the edge of the outer edge of the cap can be welded to the lead core.

[0034] According to another aspect of the present invention, a battery pack comprising the battery cell described above may be provided.

[0035] According to another aspect of the present invention, a vehicle comprising the battery pack may be provided.

[0036] According to one aspect of the present invention, a battery cell with improved assembly between a battery housing and a housing lead can be provided.

[0037] According to another aspect of the present invention, a battery cell with improved weldability between the battery housing and the housing lead, and between the battery housing and the current collector plate, can be provided.

[0038] 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.

[0039] FIG. 1 is a perspective view of a battery cell according to a first embodiment of the present invention.

[0040] Figure 2 is a perspective view showing the battery cell of Figure 1 inverted.

[0041] FIG. 3 is a drawing showing an electrode assembly, a first current collector plate, and a second current collector plate according to a first embodiment of the present invention.

[0042] FIG. 4 is a diagram showing the main components of a battery cell according to a first embodiment of the present invention.

[0043] Figure 5 is a cross-sectional view of the battery cell of Figure 2.

[0044] Figure 6 is a partial enlarged view of Figure 5.

[0045] FIG. 7 is a drawing showing a welding filter according to a first embodiment of the present invention.

[0046] Figure 8 is an enlarged view of area A of Figure 6.

[0047] FIG. 9 is a drawing corresponding to FIG. 8, and is a partial cross-sectional view of a battery cell according to a second embodiment of the present invention.

[0048] FIG. 10 is a drawing showing the state before assembly of the housing lead and the battery housing in a battery cell according to a third embodiment of the present invention.

[0049] Figure 11 is a drawing showing the state after assembly of the housing lead and battery housing of Figure 10.

[0050] FIG. 12 is a partial cross-sectional view of a battery cell according to a fourth embodiment of the present invention.

[0051] FIG. 13 is a partial cross-sectional view of a battery cell according to the fifth embodiment of the present invention.

[0052] Fig. 14 is an enlarged view of a part of Fig. 13.

[0053] Figure 15 is a drawing showing the weld bead after welding is performed between the battery housing and the housing lead in Figure 14.

[0054] FIG. 16 is a partial cross-sectional view of a battery cell according to the sixth embodiment of the present invention.

[0055] Fig. 17 is a cutaway perspective view of the battery cell of Fig. 16.

[0056] Figure 18 is a diagram showing the configuration of the housing lead of Figure 17.

[0057] FIG. 19 is a drawing for explaining a battery pack including a battery cell according to the present invention.

[0058] FIG. 20 is a drawing for explaining a vehicle including the battery pack of FIG. 19.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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 cylindrical battery cell is referred to as the axial direction. The direction surrounding an imaginary centerline passing through the center of the cylindrical 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.

[0063] FIG. 1 is a perspective view of a battery cell according to a first embodiment of the present invention, FIG. 2 is a perspective view showing the battery cell of FIG. 1 inverted, FIG. 3 is a drawing showing an electrode assembly, a first current collector plate, and a second current collector plate according to a first embodiment of the present invention, FIG. 4 is a drawing showing the main components of a battery cell according to a first embodiment of the present invention, and FIG. 5 is a cross-sectional view of the battery cell of FIG. 2.

[0064] Referring to these drawings, a battery cell (10) according to a first embodiment of the present invention includes an electrode assembly (100), a battery housing (200), and a housing lead (300).

[0065] The electrode assembly (100) comprises a first unwound portion (111) and a second unwound portion (121). Specifically, the electrode assembly (100) has a structure in which the first electrode and the second electrode and a separator interposed between them are wound around a winding axis to define a core and an outer surface.

[0066] The electrode assembly (100) applied to the present invention may be a jelly-roll type electrode assembly (100). In this case, an additional separator may be provided on the outer surface of the electrode assembly (100) to insulate it from the battery housing (200). The electrode assembly (100) may have a wound structure well known in the art, without limitation.

[0067] 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 (the Z direction parallel to the height direction of the battery cell (10) shown in FIG. 3), there is a non-coated portion where the first electrode active material is not applied. That is, the first electrode includes a non-coated portion exposed to the outside of the separator, where the active material is not coated at the long end along the winding direction. The non-coated portion functioning as an electrode tab of the first electrode is hereinafter referred to as the first non-coated portion (111). The first non-coated portion (111) is provided on the upper side in the height direction (the Z direction parallel to the height direction of the battery cell (10) shown in FIG. 3) of the electrode assembly (100) housed within the battery housing (200). That is, the first electrode includes a first uncoated portion (111) that is exposed to the outside of the separator and has no active material layer coated on the long side end, and at least a portion of the first uncoated portion (111) is used as an electrode tab itself. The first uncoated portion (111) may be, for example, a negative electrode tab.

[0068] 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), as shown in FIG. 3. The bent plurality of segments may be overlapped in multiple layers. A first current collector plate (400) may be placed on the upper portion of the first bare portion (111). For example, the first bare portion (111) and the first current collector plate (400) may be in contact, and at least one part of the contact may be welded.

[0069] 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 (a direction parallel to the Z-axis), 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 (121). The second non-coated portion (121) is located at the bottom 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 (121) 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 (121) is used as an electrode tab itself. The second non-coated portion (121) may be, for example, a positive electrode tab.

[0070] At least a portion of the second bare portion (121) may include a plurality of segments divided along the winding direction of the electrode assembly (100), similar to the first bare 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 (500) may be disposed on the lower part of the second bare portion (121). For example, the second bare portion (121) and the second current collector plate (500) may be connected by welding.

[0071] The first non-removable portion (111) and the second non-removable portion (121) extend in opposite directions along the height direction (a direction parallel to the Z-axis) of the battery. The first non-removable portion (111) extends toward the open end (210) of the battery housing (200), and the second non-removable portion (121) extends toward the closed portion (220) located opposite the open end (210).

[0072] As illustrated in FIGS. 4 and 5, the battery housing (200) may be configured to accommodate the electrode assembly (100). The battery housing (200) is a roughly cylindrical receptacle having an open end (210) formed on one side and is made of a conductive material, such as metal. The material of the battery housing (200) may be steel, stainless steel, or nickel-plated steel.

[0073] Specifically, the battery housing (200) may include a cylindrical side wall portion, a flat closed portion (220) connected to one end of the side wall portion in the height direction (Z direction), and an open portion (210) provided at the other end of the side wall portion in the height direction. The side of the side wall portion that is not connected to the closed portion (220) may be defined as the open portion (210) of the battery housing (200). The side wall portion and the closed portion (220) may be manufactured, for example, by forming a metal sheet with nickel plated on the surface of steel using a deep drawing process, and then trimming the front end of the side wall portion forming the open portion (210) with a punch while holding it with a holder.

[0074] The battery housing (200) can accommodate an electrode assembly (100) in its internal space through the open end (210). At this time, the electrode assembly (100) can be accommodated inside the battery housing (200) such that the first non-removable portion (111) faces the open end (210) and the second non-removable portion (121) faces the closed portion (220).

[0075] The battery housing (200) can be electrically connected to the first electrode of the electrode assembly (100). As illustrated in FIG. 5, the battery housing (200) can be electrically connected to the first electrode by configuring the first non-electrical portion (111) extending from the first electrode to contact the first current collector plate (400) and the first current collector plate (400) to contact the battery housing (200). In this case, the battery housing (200) has the same polarity as the first non-electrical portion (111).

[0076] The closed portion (220) of the battery housing (200) is provided with a cell terminal (600) that is insulated from the battery housing (200) and electrically connected to a second electrode. The cell terminal (600) is made of a conductive metal material. For example, aluminum (Al) may be used as the material for the cell terminal (600). For instance, as shown in FIG. 5, the second non-circulating portion (121) is connected to a second current collector plate (500), and the second current collector plate (500) may be connected to a cell terminal (600) that is provided to pass through the closed portion (220) in an axial direction. In this case, the cell terminal (600) has the same polarity as the second electrode. Therefore, the cell terminal (600) is electrically connected to the second electrode of the electrode assembly (100) and has the same second polarity as the second electrode. These cell terminals (600) can be configured to be electrically connected to a first electrode and electrically insulated from a battery housing (200) having a first polarity.

[0077] Electrical insulation between the cell terminal (600) and the battery housing (200) can be achieved in various ways. For example, insulation can be achieved by interposing an insulator (224) between the second current collector plate (500) and the closed portion (220) of the battery housing (200), and by interposing an insulating gasket (223) between the cell terminal (600) and the battery housing (200). Alternatively, insulation can be achieved by forming an insulating coating layer on a part of the cell terminal (600). Alternatively, a method of structurally and firmly fixing the cell terminal (600) so that contact between the cell terminal (600) and the battery housing (200) is impossible may be applied. Alternatively, multiple methods among those described above may be applied together.

[0078] Meanwhile, the battery housing (200) can be sealed by attaching a housing lid (300) to the open end (210).

[0079] The housing lid (300) according to the present embodiment may be provided with a vent notch (312) configured to rupture when the pressure inside the battery housing (200) exceeds a critical value. For example, the vent notch (312) may be formed on both sides of the housing lid (300) and may be formed as at least one pattern among a continuous circular pattern, a discontinuous circular pattern, and a straight pattern on the surface of the housing lid (300). Additionally, the vent notch (312) may be formed in various other patterns.

[0080] Additionally, the housing lead (300) may be provided with an electrolyte injection hole (314) in the center. The electrolyte injection hole (314) may be configured to face a cavity (S1) formed in the center of the winding core of the electrode assembly (100). Furthermore, the first current collector plate (400) may be provided with a center hole (411) in the center facing the electrolyte injection hole (314).

[0081] For example, after attaching a housing lead (300) to the open end (210) of the battery housing (200), the electrolyte can be injected into the interior of the battery housing (200) through the electrolyte injection hole (314) and the center hole (411). The electrolyte injection hole (314) can be closed after the electrolyte injection is completed. For example, the electrolyte injection hole (314) can be sealed with a lead hole cap (315) provided in the form of a disc made of metal material. As an alternative to the present embodiment, the electrolyte injection hole (314) may be sealed by pressing a ball (not shown) into the electrolyte injection hole (314). 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 (314). Meanwhile, unlike the present embodiment, the electrolyte injection may be performed by making a terminal hole in the cell terminal (600) provided in the closed portion (220) of the battery housing (200), injecting the electrolyte, and closing the terminal hole. In this case, the lead hole cap (315) and the electrolyte injection hole (314) may be omitted from the housing lead (300).

[0082] In the battery cell (10) according to the present invention, the open end (210) is formed to be inclined from the inside toward the outside and has an inclined portion (212) that guides the press fit of the housing lid (300). Here, the inclined portion (212) may be specified as an inner surface portion of the open end (210) that is inclined with respect to the axial direction of the battery housing (see FIG. 7). Alternatively, the inclined portion (212) may be specified as a portion that is provided at the end in the height direction from the inner surface of a cylindrical side wall and is inclined with respect to the axial direction of the battery housing (200). The inclined portion (212) may take the form of a chamfer formed along the inner edge of the cylindrical side wall at the open end (210).

[0083] And the housing lid (300) includes a lid outer portion (320) having a butting surface (321, 322) facing the inner surface of the open end (210), and the butting surface (321, 322) is provided to extend longer in the axial direction (Z direction) of the battery housing (200) than the height of the inclined portion (212).

[0084] As will be described in detail later, according to the above configuration, assembly convenience and airtightness between the open end (210) of the battery housing (200) and the housing lead (300) after press fitting are increased, and alignment errors can be reduced. Accordingly, the welding quality of the battery housing (200) and the housing lead (300) can be improved.

[0085] Specifically, the housing lead (300) according to the present embodiment is provided in a roughly disc shape and is arranged so that its diameter corresponds to the inner diameter of the battery housing (200). As shown in FIGS. 5 and 6, the housing lead (300) includes a lead central portion (310) extending radially from its center and a lead outer portion (320) offset axially from the lead central portion (310) and located radially outside the lead central portion (310).

[0086] The housing lead (300) may be configured to be press-fitted into the open end (210) of the battery housing (200) such that the outer portion (320) of the lead contacts at least a portion of the inner surface of the open end (210).

[0087] As shown in FIG. 7, the open end (210) comprises a first vertical section (211) forming part of the inner surface, an inclined section (212) forming the remaining part of the inner surface and extending obliquely in the direction of the outer surface from the end of the first vertical section (211), a horizontal section (213) extending horizontally in the direction of the outer surface from the end of the inclined section (212), and a second vertical section (214) connected to the end of the horizontal section (213) and forming the outer surface.

[0088] And the outer part (320) of the housing lead (300) is provided to have a shape in which the length (D2) of the abutting surface (321, 322) is extended longer in the axial direction (Z direction) than the height (D1) of the inclined part (212).

[0089] According to the above configuration, when the housing lid (300) is press-fitted into the open end (210), the outer portion (320) of the lid can be easily inserted into the inward direction of the guide battery housing (200) on the inclined surface of the inclined portion (212). Additionally, it may be easy to align the open end (210) and the housing lid (300) so that the first horizontal portion (213) of the open end (210) and the upper surface of the outer portion (320) of the lid are located on the same plane.

[0090] To elaborate, for example, when inserting the housing lead (300) into the battery housing (200) in a state where there is no inclined portion (212) on the open end (210) as in the present embodiment, if the first vertical portion (211) of the open end (210) and the side of the outer portion (320) of the lead are misaligned even slightly in the radial direction, it is difficult to insert the housing lead (300) into the battery housing (200). At this time, if the housing lead (300) is pushed in excessively, damage and deformation of the open end (210) may occur. However, according to the present embodiment, if the first vertical portion (211) of the open end (210) and the side of the outer portion (320) of the lead are slightly misaligned just before the housing lead (300) is inserted into the battery housing (200), the lower part of the outer portion (320) of the lead may be guided along the inclined surface of the inclined portion (212) during the process of pushing the housing lead (300) into the battery housing (200), thereby inducing the first vertical portion (211) of the open end (210) and the abutting surfaces (321, 322) of the outer portion (320) of the lead to come into contact.

[0091] In addition, in this embodiment, since the outer part of the lead (320) is thicker than the height of the inclined part (212) of the open end (210), the insertion depth of the housing lead (300) can be adjusted so that the height of the horizontal part (213) of the open end (210) and the upper surface of the outer part of the lead (320) are at the same level when the first vertical part (211) of the open end (210) and the side of the outer part of the lead (320) are in contact.

[0092] That is, the abutting surfaces (321, 322) of the outer part (320) of the lead according to this embodiment may include a first abutting surface (321) that is spaced apart from the inclined part (212) and has a predetermined gap between it and the inclined part (212), as shown in FIG. 7, and a second abutting surface (322) that is arranged to make face-to-face contact with the first vertical part (211).

[0093] When the housing lid (300) is assembled to the open end (210) with the structure as described above, almost no gap occurs between the first vertical section (211) and the second butting surface (322). In this state, the first vertical section (211) and the second butting surface (322) can be strongly joined by, for example, laser welding in the gap between the inclined section (212) and the first butting surface (321). By performing laser welding in the gap in this way, the amount of the weld bead protruding out of the gap can be reduced. That is, according to the configuration of this embodiment, the weld bead fills the gap and is welded, so there is almost no change in the total height of the battery cell. For reference, in this embodiment, the height of the inclined section (212) provided in the open end (210) may be 0.1mm to 0.4mm.

[0094] The ratio of the height (D1) of the inclined portion and the length (D2) of the abutting surface of the outer side of the lead may be 1:2.5 to 1:10, and preferably 1:5.

[0095] For example, if the height (D1) of the inclined portion is excessively large, the laser is irradiated deep into the inside of the battery housing during laser welding, increasing the risk of damage to the electrode assembly and / or the first current collector plate. To reduce this risk of damage to the electrode assembly and / or the first current collector plate, the thickness of the housing lead can be increased more than the height of the inclined portion. However, as the thickness of the housing lead that is forcibly fitted into the battery housing increases, the internal space of the battery housing decreases, and thus the disadvantage of reduced energy density arises. Accordingly, the battery cell according to the present invention may have a value such that the risk of damage to the electrode assembly and / or the first current collector plate due to laser welding is minimized at a level where energy density is not reduced, and the height (D1) of the inclined portion (212) is 0.2 mm and the length (D2) of the butting surface (321, 322) is 1 mm.

[0096] Meanwhile, referring again to FIGS. 3, 5 to 8, the battery cell (10) according to the present embodiment further includes a welding filler (700) to ensure electrical connection reliability between the battery housing (200) and the first current collector plate (400). The welding filler (700) may be placed in an area where the edge of the first current collector plate (400) and the inner surface of the battery housing (200) come into contact.

[0097] Specifically, the first collector plate (400) according to the present embodiment includes a plate center portion (410), a plate outer portion (420), an inclined connecting portion (430) connecting the plate center portion (410) and the plate outer portion (420), and an edge bending portion (440).

[0098] The central portion of the plate (410) may be in contact with the first bare portion (111) and may be joined to the first bare portion (111) by, for example, laser welding or ultrasonic welding. The outer portion of the plate (420) may be axially offset from the central portion of the plate (410), spaced apart from the first bare portion (111), extended in a centrifugal direction, and arranged to be in contact with the first vertical portion (211) of the open end (210). The edge bend portion (440) may be extended obliquely toward the outer portion of the lead (320) from the end of the outer portion of the plate (420) that contacts the first vertical portion (211).

[0099] In one embodiment of the present invention, the edge bend portion (440) forms a predetermined angle with the first vertical portion (211). The predetermined angle may be an acute angle. For example, the predetermined angle may be 30° to 60°. Due to the formation of the angle, a surplus space may be formed between the edge bend portion (440) and the first vertical portion (211). A welding filler (700) may be interposed in the surplus space. When welding the first current collector plate (400) and the battery housing (200), the welding filler (700) is melted, thereby allowing the first current collector plate (400) and the battery housing (200) to be smoothly joined even if a gap exists between the inner surface of the first current collector plate (400) and the battery housing (200).

[0100] The welding filler (700) may be interposed in the excess space enclosed by the edge bend (440) of the first collector plate (400), the first vertical portion (211) of the open end (210), and the lead outer portion (320) of the housing lead (300). The welding filler (700) may be provided in a shape that fits into the excess space. By heat-melting the welding filler (700), the first vertical portion (211), the edge bend (440), and the lead outer portion (320) may be integrally joined.

[0101] The welding filler (700) may be provided with a metal material having electrical conductivity that has a lower melting point (melting point) than the battery housing (200), the second current collector plate (500), and the housing lead (300). By using the filler metal, the welding filler (700) melts at a temperature lower than the melting temperature of the battery housing (200), the first current collector plate (400), and the housing lead (300), so triple welding of the battery housing (200), the first current collector plate (400), and the housing lead (300) is possible with low output.

[0102] The welding filler (700) may be located inside the battery housing (200) to limit the depth to which the housing lead (300) is inserted into the battery housing (200). For example, the welding filler (700) is placed in the excess space formed by the first vertical portion (211) of the open end (210) and the bent portion of the first current collector plate (400). Here, the welding filler (700) may be provided in a ring shape, as shown in FIG. 8. According to the above configuration, when the housing lead (300) is inserted into the battery housing (200), when a predetermined depth is reached, the lower surface of the outer portion (320) of the lead comes into contact with the upper surface of the welding filler (700). In this way, if the insertion depth of the housing lead (300) is limited, the assembly tolerance between the housing lead (300) and the open end (210) of the battery housing (200) can be reduced.

[0103] Next, with reference to FIGS. 9 to 12, a battery cell (10) according to other embodiments of the present invention will be described.

[0104] 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.

[0105] FIG. 9 is a drawing corresponding to FIG. 8 and is a partial cross-sectional view of a battery cell (10) according to another embodiment of the present invention.

[0106] In the case of a battery cell according to the second embodiment of the present invention, the inclined portion (212A) of the open end (210) may be formed as a curved surface. As shown in FIG. 9, the inclined portion (212A) may be configured such that the slope increases as the outer portion (320) of the lead is inserted. In this case, compared to the first embodiment described above, it is advantageous to reduce the height of the slope and secure a wider contact area between the first vertical portion (211) and the second abutting surface (322), thereby further enhancing the sealing performance by the housing lead (300).

[0107] FIG. 10 is a drawing showing the state before assembly of the housing lead (300) and the battery housing (200) in a battery cell according to a third embodiment of the present invention, and FIG. 11 is a drawing showing the state after assembly of the housing lead (300) and the battery housing (200) of FIG. 10.

[0108] The outer portion (320) of the housing lead (300) according to the third embodiment of the present invention includes a first abutting surface (321A) inclined to make face contact with the inclined portion (212) of the open end (210), and a second abutting surface (322A) provided to make face contact with the first vertical portion (211).

[0109] As illustrated in FIGS. 10 and 11, when the housing lid (300) is seated on the open end (210) of the battery housing (200), the second abutting surface (322A) of the outer part (320) of the lid can be guided to be inserted into the correct position by the inclined part (212) of the open end (210), and the first abutting surface (321A) of the outer part (320) of the lid can come into face contact with the inclined part (212). In this case, the gap between the outer part (320) of the housing lid (300) and the open end (210) of the battery housing (200) is minimized and the contact area is maximized, so that airtightness can be further enhanced during welding.

[0110] FIG. 12 is a partial cross-sectional view of a battery cell (10) according to a fourth embodiment of the present invention.

[0111] According to the fourth embodiment of the present invention, the outer portion (320) of the housing lid (300) includes a first abutment surface (321B) inclined to make face contact with the inclined portion (212) of the open end (210), and a second abutment surface (322B) that extends at the same angle as the first abutment surface (321B) and is inserted into the interior of the battery housing (200).

[0112] That is, as illustrated in FIG. 12, the first butting surface (321B) and the second butting surface (322B) of the outer part of the lead (320) are arranged to extend at the same angle. In this case, when the housing lead (300) is seated on the open end (210) so that the first butting surface (321B) and the inclined portion (212) of the open end (210) come into face-to-face contact, the outer part of the lead (320) is no longer inserted into the interior of the battery housing (200). Therefore, alignment between the housing lead (300) and the open end (210) can be made easier. Meanwhile, according to the fourth embodiment, a gap exists between the first vertical portion (211) of the open end (210) and the second butting surface (322B) of the outer part of the lead (320). A welding filler (700) can be filled into the gap. That is, in the fourth embodiment, the welding filler (700) may be interposed in the excess space surrounded by the first vertical section (211), the bent section of the first collector plate (400), and the second butting surface (322B). In this case, the welding filler (700) may be heat-melted so that the battery housing (200), the housing lid (300), and the first collector plate (400) are integrally joined.

[0113] FIG. 13 is a partial cross-sectional view of a battery cell according to a fifth embodiment of the present invention, FIG. 14 is an enlarged view of a partial part of FIG. 13, and FIG. 15 is a drawing showing a weld bead after welding is performed between the battery housing and the housing lead in FIG. 14.

[0114] As illustrated in FIG. 13, the housing lead (300) according to the fifth embodiment of the present invention may be configured to be directly joined to the first non-removable portion (111) without the first collector plate (400).

[0115] When the housing lead (300) is pressed into the battery housing (200), the housing lead (300) can be pressed in, for example, until the bottom surface (axial inner surface) of the lead center (310A) is in close contact with the first bare portion (111) of the electrode assembly (100). As indicated by W1 in FIG. 13, the first bare portion (111) can be joined to the housing lead (300) by welding. The welding can be performed by a laser irradiated from the axial outer surface of the lead center (310A) from the axial outer side. The laser can be irradiated in a scanning manner along the radial direction to form a weld that extends radially. In this way, the housing lead (300) can function as a cover that closes the open end (210) of the battery housing (200) and also function as the first current collector plate (400) in the aforementioned embodiments.

[0116] Additionally, as illustrated in FIGS. 13 and 14, the outer portion of the lead (320) may include a butting surface (321C, 322C) and a curved surface (323) in sequence from the radially outer to the inner side. The butting surface (321C, 322C) and the curved surface (323) may be configured in a roughly U-shape.

[0117] A housing lid (300) having a U-shaped outer portion (320) is suitable for being pressed into the open end (210) of a battery housing (200). The curved surface (323) provides a cross-sectional shape that allows the housing lid (300) to be elastically deformed radially inward. Accordingly, when the housing lid (300) is pressed into the open end (210), the U-shaped outer portion (320) is compressed and then expanded, allowing the housing lid (300) to be fitted into the open end (210) without causing deformation of other parts as much as possible. Accordingly, a radial contact force can be secured between the first vertical portion (211) and the second abutting surface (322C) of the open end (210). In other words, during the process of pressing the housing lead (300) into the open end (210) of the battery housing (200), the butting surfaces (321C, 322C) can be strongly butted without being twisted.

[0118] A battery cell according to the present invention includes a weld bead (WB) provided in a predetermined gap between the inclined portion of the open end and the first abutting surface of the housing lead. As previously described, by performing laser welding (W2) in the gap between the inclined portion (212) of the open end (210) and the first abutting surface (321C) of the outer portion (320) of the lead, the amount of the weld bead (WB) protruding out of the gap can be reduced, as shown in FIG. 15. That is, the weld bead (WB) generated when welding the housing lead (300) to the open end (210) of the battery housing (200) fills the gap, so there is almost no change in the total height of the battery cell.

[0119]

[0120] FIG. 16 is a partial cross-sectional view of a battery cell according to a sixth embodiment of the present invention, FIG. 17 is a cutaway perspective view of the battery cell of FIG. 16, and FIG. 18 is a drawing showing the configuration of the housing lead of FIG. 17.

[0121] The battery cell according to the 6th embodiment of the present invention includes a housing lead (300A) having a U-shaped outer lead portion (320), similar to the battery cell according to the 5th embodiment described above.

[0122] That is, the outer part of the lead (320) may include a butt surface (321C, 322C) and a curved surface (323) in sequence from the radially outer side (see FIG. 15) to the inner side. The butt surface (321C, 322C) and the curved surface (323) may be configured in a roughly U-shape. Laser welding (W2) may be performed in the gap between the inclined part (212) of the open end (210) and the first butt surface (321C) of the outer part of the lead (320). The laser welding (W2) may be performed continuously along the circumferential direction of the battery housing (200).

[0123] Additionally, the housing lead (300A) of the battery cell according to the sixth embodiment of the present invention, with reference to FIGS. 16 and 17, may include a lead core portion (330) that is convexly arranged to be spaced apart from the first non-retaining portion (111) in the axial direction (Z direction) and an electrode contact portion (340) configured to make direct contact with the first non-retaining portion (111) in the axial direction between the lead core portion (330) and the lead outer portion (320).

[0124] The electrode contact portion (340) can be combined with the electrode assembly (100). The bottom surface of the electrode contact portion (340) (the surface facing the electrode assembly (100)) can be joined to the electrode assembly (100) by being welded face-to-face.

[0125] The electrode contact portion (340) may provide a bottom surface that extends flatly in the radial direction. The height of the bottom surface of the electrode contact portion (340) may be lower than the bottom surface of the lead outer portion (320). That is, the electrode contact portion (340) may protrude further toward the electrode assembly (100) than the lead outer portion (320). Accordingly, the bonding process between the electrode contact portion (340) and the electrode assembly (100) can be performed smoothly.

[0126] As in the sixth embodiment of the present invention, by combining the electrode assembly (100) and the housing lead (300A) so that the electrode contact portion (340) contacts the first non-contact portion (111), the welding process between the first current collector plate (400) and the battery housing (200) can be omitted. Accordingly, it is possible to reduce component costs and simplify the assembly process by removing the first current collector plate (400).

[0127] The electrode contact portion (340) according to the present embodiment may be provided in a form divided into three regions along the circumferential direction of the housing lead (300A). That is, the electrode contact portion (340) of the present embodiment includes a first electrode contact portion (340A), a second electrode contact portion (340B), and a third electrode contact portion (340C) as shown in FIG. 18. Specifically, the three electrode contact portions (340A, 340B, 340C) are provided discontinuously at a predetermined distance apart along the circumferential direction with respect to the lead core portion (330). The three electrode contact portions (340A, 340B, 340C) may each be formed to be recessed from the remaining parts of the housing lead (300A) and configured to be in close contact facing the first non-receptor portion (111). A bridge portion (350) is provided between two adjacent electrode contact portions (340) along the circumferential direction. The bridge portion (350) is formed convexly so as to be separated from the first non-removable portion (111). The two electrode contact portions (340) are isolated from each other by this bridge portion (350). In this embodiment, there are three bridge portions (350), and the three bridge portions (350) may be spaced apart at equal intervals along the circumferential direction relative to the lead core portion (330). Bridge portions (350) may be provided at every 120-degree angle along the circumferential direction relative to the lead core portion (330).

[0128] Although FIG. 18 shows three electrode contact portions (340) and three corresponding bridge portions (350), in other embodiments (not shown), the number of electrode contact portions and bridge portions may be more or fewer. For example, an arrangement may be provided in which bridge portions are interposed between electrode contact portions to have n-fold rotational symmetry for three or more integers n centered around the lead core portion (330).

[0129] According to this configuration, sufficient adhesion can be secured between the housing lead (300A) and the first non-contact portion (111) of the electrode assembly (100). Additionally, because the housing lead (300A) is locally in contact with the first non-contact portion (111) of the electrode assembly (100) by the three divided electrode contact portions (340) and is recessed compared to other parts, when the internal pressure of the battery housing (200) increases, the three electrode contact portions (340A, 340B, 340C) can be deformed convexly outward in the axial direction and detach from the first non-contact portion (111). That is, when a thermal event occurs in the battery cell, the housing lead (300A) expands outward due to the internal pressure of the battery housing (200), and the electrode contact portion (340) can be separated from the first non-contact portion (111). In this case, the electrical connection between the battery housing (200) and the first electrode can be severed, thereby blocking the flow of current through the battery cell. That is, a function similar to a fuse can be achieved by the above configuration.

[0130] Again, referring to FIGS. 16 to 18, the housing lead (300A) according to the present embodiment further includes an electrolyte injection hole (314) and a plug cap (360) that seals the electrolyte injection hole (314).

[0131] The above electrolyte injection hole (314) can be formed axially through the central region of the lead core portion (330).

[0132] The plug cap (360) may include a cap outer portion (361) facing the surface of the lead core portion (330) outside the electrolyte injection hole (314), and a cap central portion (362) provided in a shape protruding more than the cap outer portion (361) so as to be pressed into the electrolyte injection hole (314).

[0133] The outer cap portion (361) can be seated facing the stepped portion (331) formed in the lead core portion (330). Additionally, the sealing force can be increased by welding the end of the outer cap portion (361) and the lead core portion (330) along the perimeter of the outer cap portion (361).

[0134] The central portion of the cap (362) may be provided to protrude axially from the outer portion of the cap (361) so as to be pressed into the electrolyte injection hole (314). That is, the central portion of the cap (362) may be configured to be pressed into the interior of the electrolyte injection hole (314).

[0135] The outer cap portion (361) extends radially from the electrolyte injection hole (314) to the lead core portion (330). Due to this outer cap portion (361), the depth to which the central cap portion (362) is pressed into the electrolyte injection hole (314) may be limited. Additionally, the edge of the outer cap portion (361) where welding is performed is spaced apart from the electrolyte injection hole (314) by a predetermined distance, thereby minimizing interference with the electrolyte that may remain around the electrolyte injection hole (314) during welding. The distance between the edge of the outer cap portion (361) and the electrolyte injection hole (314) may be 1.5 mm to 3.5 mm.

[0136] The battery cell described above can be housed in the housing (2) of the battery pack (1) as illustrated in FIG. 19. The battery pack (1) may be constructed using a battery module, which is an intermediate form of assembly, or the battery pack (1) may be constructed directly without a battery module as illustrated. As in the present embodiment, the battery pack (1) in which the battery cell is housed directly in the housing (2) of the battery pack (1) without a battery module can be realized with a higher energy density.

[0137] 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. 20, the vehicle's mileage relative to energy can be further increased.

[0138] A vehicle (V) according to the first embodiment of the present invention includes a battery pack (1) according to the first embodiment of the present invention. The vehicle (V) may be configured to operate by receiving power from the battery pack (1) according to the first embodiment of the present invention.

[0139] 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.

[0140] 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 having an open end so that the electrode assembly is inserted therein; and It includes a housing lead coupled to the open end of the battery housing, and The above-mentioned open end is formed to be inclined from the inner side toward the outer side and has an inclined portion that guides the interference fit of the housing lid, and A battery cell characterized in that the housing lead comprises an outer portion of the lead having a butting surface that contacts the open end, and the butting surface extends longer in the axial direction of the battery housing than the inclined portion.

2. In Paragraph 1, The above-mentioned open end is, A first vertical section forming a part of the inner surface; The inclined portion forming the remaining part of the inner surface and extending obliquely in the direction of the outer surface from the end of the first vertical portion; A horizontal portion extending horizontally from the end of the inclined portion toward the outer surface; and a second vertical portion connected to the end of the horizontal portion and forming the outer surface, A battery cell characterized in that the housing lead has an outer portion of the lead that contacts at least a portion of the inner surface of the open end.

3. In Paragraph 2, The above butting surface is, A first abutting surface spaced apart from the inclined portion and arranged to have a predetermined gap with respect to the inclined portion; and, A battery cell characterized by including a second butt surface arranged to make face-to-face contact with the first vertical portion.

4. In Paragraph 3, A battery cell characterized by having a weld bead formed in the predetermined gap provided between the inclined portion and the first butting surface.

5. In Paragraph 2, The above butting surface is, A first butting surface inclined to make face contact with the above-mentioned inclined portion; and A battery cell characterized by including a second abutting surface arranged to make face-to-face contact with the first vertical portion.

6. In Paragraph 2, The above butting surface is, A first butting surface inclined to make face contact with the above-mentioned inclined portion; and A battery cell characterized by including a second abutting surface that extends at the same angle as the first abutting surface and is inserted into the interior of the battery housing.

7. In Paragraph 2, A battery cell characterized by the above-mentioned inclined portion being configured such that the slope increases as it moves toward the direction in which the outer part of the lead is inserted.

8. In Paragraph 1, A battery cell characterized by the height of the inclined portion being 0.1mm to 0.4mm.

9. In Paragraph 1, A battery cell characterized in that the ratio of the height of the inclined portion to the length of the abutting surface of the outer side of the lead is 1:2.5 to 1:

10.

10. In Paragraph 2, It includes a first current collector plate electrically connected to the first electrode inside the battery housing, and The above-mentioned first collector plate is, A central part of a plate in contact with a first non-removable portion extending from the first electrode; An outer plate portion offset axially from the central portion of the plate, spaced apart from the first non-removable portion, and extended in a centrifugal direction to contact the first vertical portion of the open end; and A battery cell characterized by including an edge bend portion that extends obliquely toward the outer side of the lead from the end of the outer portion of the plate that contacts the first vertical portion.

11. In Paragraph 10, It further includes a welding filler interposed in the excess space surrounded by the first vertical portion, the edge bend portion, and the lead outer portion, and A battery cell characterized by the first vertical portion, the edge bend portion, and the lead outer portion being integrally welded by the welding filler.

12. In Paragraph 11, A battery cell characterized in that the above-mentioned welding filler has a shape that fits into the above-mentioned excess space.

13. In Paragraph 11, A battery cell characterized in that the welding filler is a metal material with a lower melting point than the battery housing, the first current collector plate, and the housing lead.

14. In Paragraph 11, A battery cell characterized in that the welding filler is located inside the battery housing to limit the depth to which the housing lead is inserted into the battery housing.

15. In Paragraph 1, It includes a first current collector plate disposed between the electrode assembly and the housing lead inside the battery housing and electrically connected to the first electrode, The above housing lead is provided with an electrolyte injection hole in the center. The center of the first current collector plate is provided with a center hole facing the electrolyte injection hole, A battery cell characterized in that the center hole is positioned to face a cavity in the center of the winding core provided in the electrode assembly in the axial direction.

16. In Paragraph 1, A battery cell characterized in that the outer part of the lead is provided in a 'U' shape.

17. In Paragraph 1, The above housing lead is, A battery cell characterized by including a lead central portion connected to the outer portion of the lead and configured to make direct axial contact with a first non-removable portion extending from the first electrode.

18. In Paragraph 1, The above housing lead comprises: a lead core portion that is convexly provided, spaced axially from a first non-retaining portion located at the center of the housing lead and extending from the first electrode; and A battery cell characterized by including an electrode contact portion configured to make direct axial contact with the first non-retaining portion between the lead core portion and the lead outer portion.

19. In Paragraph 18, A battery cell characterized in that the electrode contact portion is divided into three regions along the circumferential direction of the housing lead.

20. In Paragraph 18, The above lead core portion is provided with an electrolyte injection hole formed through in the axial direction, and The above housing lead further includes a plug cap covering the electrolyte injection hole, and A battery cell characterized in that the plug cap comprises an outer cap portion facing the surface of the lead core portion at the outside of the electrolyte injection hole, and a central cap portion formed to protrude more than the outer cap portion so as to be pressed into the electrolyte injection hole.

21. In Paragraph 20, The outer edge of the above cap is spaced from the electrolyte injection hole by 1.5m to 3.5mm, and A battery cell characterized by the edge of the outer portion of the cap being welded to the lead core portion.

22. A battery pack characterized by including at least one battery cell described in any one of claims 1 to 21.

23. An automobile comprising the battery pack described in paragraph 22.

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