Structure for sealing injection port of battery can, battery cell using same, battery pack and vehicle

Abstract

The present invention relates to a structure for sealing a lid injection port of a battery can. The present invention comprises: an injection port provided on a battery can or lid made of a metal material; a plug made of a metal material for completing the injection port; and a hot melting unit interposed between the plug and a peripheral region of the injection port, and thermally fused by heat at the periphery of the plug and the injection port. The hot melting unit may include: a first chromium plating layer applied to a periphery of the injection port; a second chromium plating layer applied to the stopper; and a hot melt layer comprising polypropylene-maleic anhydride (PP-MAH), wherein any one of the two chromium plating layers is provided as a substrate. Chromium oxide and PP-MAH of the chromium plating layer can be chemically bonded with each other through hot melting.

Description

Technical Field

[0001] The present invention relates to a structure for sealing a liquid injection port of a battery can, a battery cell using the structure, a battery pack including the battery cell, and a vehicle equipped with the battery pack. Background Art

[0002] Cylindrical battery cells, which are structures that house a jelly-roll-type electrode assembly in a cylindrical metal can, are more resistant to shock and temperature than pouch-type batteries. As a result, there is a growing demand for metal can cells as battery cells for vehicle battery packs.

[0003] The process of manufacturing a battery cell using a cylindrical battery can includes deep drawing a metal sheet to form a circular bottom and a circular tubular side wall member connected to the circular bottom, housing an electrode assembly in the battery can, and covering an open end of the side wall member with a cover.

[0004] For a structure in which the open end of the battery can is covered with a cover and the cover and the battery can are fixed, crimping or seam welding may be applied.

[0005] Crimping is a method in which, after injecting electrolyte into a battery can through the open end of the battery can, the open end is covered with a lid, and then the front end of the side wall portion of the battery can is crimped or crimped to compress and fix the lid edge. Although crimping has the advantage of not generating heat that may cause deterioration or ignition of the electrolyte filled in the battery can during processing, crimping has the disadvantage of a complicated lid fixing structure and occupies the internal volume of the battery can, thereby reducing energy density.

[0006] Reference Figures 1 to 6 Seam welding is a process of making the periphery of the top of the side wall portion 11 of the battery can 10 contact the periphery of the edge of the cover 40 and welding along the circumferential direction thereof, so that a larger volume of electrode assembly can be accommodated in the battery can due to its simple fixing structure. Therefore, in terms of the volume of the battery can, seam welding is more advantageous in ensuring the electric capacity.

[0007] However, when welding is performed by filling a battery can with an electrolyte and then covering the open end of the battery can with a lid, the electrolyte is likely to deteriorate or catch fire due to high temperature generated by welding.

[0008] Therefore, when the cover is to be fixed by seam welding the periphery of the open end of the battery can and the cover, the following method can be applied: prepare a battery can 10 having a liquid injection port at the bottom or a cover 40 having a liquid injection port 42; after accommodating the electrode assembly in the battery can and seam welding the battery can 10 and the cover, inject electrolyte through the liquid injection port 42 provided at the bottom of the cover or the battery can; after completing the liquid injection, close and seal the liquid injection port with a plug.

[0009] As a method of closing the liquid injection port 42 after injecting the electrolyte through the liquid injection port, seam welding of a metal plug, blind riveting, metal ball insertion, or the like can be used.

[0010] First, refer to Figure 1 and Figure 2 In the seam welding of the metal plug, the liquid injection port 42 provided in the battery can 10 is covered with a metal plug 50, and then the edge of the plug 50 is seam welded to the cover 40 to form a welded portion W. During the seam welding process, for example, when the battery can and the cover are made of SUS, the surface temperature may rise to 1400 degrees Celsius (which is the melting point of SUS). Such high temperature heat may cause the electrolyte to catch fire. That is, the method of sealing the liquid injection port by seam welding the metal plug directly violates the purpose of adopting the liquid injection port structure, that is, minimizing the effect of the heat generated during the seam welding of the open end circumference of the battery can with the cover on the electrolyte. In addition, although an additional structure that can prevent the electrolyte from catching fire can be applied to prevent this phenomenon, this additional structure will inevitably occupy more volume of the internal space of the battery cell, which is disadvantageous in ensuring the capacity of the battery can.

[0011] In such Figure 3 and Figure 4 In the sealing method using the blind rivet 58 shown, a heavy load is applied to the bonding area when the metal is plastically deformed in order to perform mechanical sealing. This heavy load may damage the coating formed on the surface of the cover 40 and the rivet 58 for preventing leakage. That is, when the load is reduced to prevent damage to the coating, the sealing performance is weakened; and when the load is increased to improve the sealing performance, the coating may be damaged and the seal may be broken. In addition, since the rivet is inserted into the battery can before riveting, a space for rivet insertion should be ensured inside the battery can, which may result in a reduction in the available volume inside the battery can.

[0012] In such Figure 5 and Figure 6 In the metal ball insertion method shown, the inner peripheral surface of the liquid injection port 42 must be extended in the axial direction to fix the metal ball 59. However, this structure is disadvantageous in terms of ensuring the internal volume of the battery can. In addition, since a heavy load is applied to the electrode when the ball 59 is pressed into the liquid injection port 42, there is a possibility that the electrode may be damaged. Summary of the invention

[0013] Technical issues

[0014] To solve the above problems, one object of the present invention is to provide a sealing structure for a liquid injection port, which can form a strong chemical bond between the plug and the cover to ensure reliable sealing. At the same time, during the liquid injection port closing process, no heavy load will be imposed on the cover part around the liquid injection port, and no high-temperature heating is required.

[0015] Another object of the present invention is to provide a sealing structure for a liquid injection port that can prevent electrolyte denaturation or fire by suppressing high-temperature heat, and reliably prevent leakage by chemical bonding sealing rather than relying on mechanical sealing without applying a heavy load to the bonding area of ​​the cover.

[0016] Another object of the present invention is to provide a method for sealing a liquid injection port that does not affect an electrode or an electrolyte contained in a battery can, and a sealing structure of a liquid injection port using the method.

[0017] Still another object of the present invention is to provide a sealing structure for a liquid injection port that can maximize the internal volume of a battery cell.

[0018] Another object of the present invention is to provide a battery cell using the above sealing structure.

[0019] Still another object of the present invention is to provide a battery pack including the battery cell, and a vehicle equipped with the battery pack and powered by electric energy provided by the battery pack.

[0020] The technical problem to be solved by the present invention is not limited to the above-mentioned purpose, and other purposes and advantages not mentioned in the present invention can be understood through the following description, and will be more clearly understood through the examples of the present invention. In addition, it is obvious that the purposes and advantages of the present invention can be achieved by the means indicated in the claims and their combinations.

[0021] Technical Solution

[0022] To solve the above problems, the present invention provides a sealing structure for a liquid injection port, wherein the liquid injection port provided in a battery can or a cover made of a metal material is closed with a metal stopper.

[0023] The battery can and cover may be manufactured from materials including aluminum or steel.

[0024] The plug may be manufactured from materials including aluminium or steel.

[0025] The battery can may be cylindrical.The battery can may include a circular tubular side wall portion and a bottom connected to one axial end of the side wall portion.

[0026] The cover may cover an open end disposed at the other axial end of the battery can.

[0027] The edge of the cover may be thermally bonded to the periphery of the other axial end of the side wall portion of the battery can.

[0028] Thermal bonding may be accomplished by welding, brazing or soldering.

[0029] The present invention does not exclude the method of fixing the cover to the battery can by crimping.

[0030] The liquid injection port may be provided at the lid or the bottom of the battery can.

[0031] The liquid injection port may be provided at a central portion of the cover or a central portion of the bottom.

[0032] The cross-section of the stopper covering the liquid injection port surrounds the liquid injection port and is larger than the cross-section of the liquid injection port.

[0033] The liquid injection port may be circular. The stopper may be concentric with the circular liquid injection port and may have a circular plate shape having a radius greater than that of the liquid injection port.

[0034] The periphery of the surface of the stopper facing the liquid injection port surrounds the liquid injection port and can be in close contact with the periphery of the liquid injection port of the bottom or cover of the battery can where the liquid injection port is provided.

[0035] A heat-fused portion is interposed between a surface #1 of the battery can or the lid surrounding the liquid injection port and a surface #2 of the plug in contact with the surface #1.

[0036] That is, surface #1 and surface #2 may refer to portions where the liquid injection port and the stopper are in contact with each other when the liquid injection port is closed with the stopper.

[0037] The heat-fused portion is fused to at least a portion of the surface #1 and the surface #2 in a closed loop shape surrounding the liquid injection port.

[0038] The heat-fused portion includes: a first chrome-plated layer disposed on surface #1; a second chrome-plated layer disposed on surface #2; and a heat-fused layer, both sides of which are in contact with the first chrome-plated layer and the second chrome-plated layer, respectively, and containing PP-MAH (polypropylene-maleic anhydride) bonded to the first chrome-plated layer and the second chrome-plated layer by heating.

[0039] The chrome plating layer can be formed by chromate surface treatment.

[0040] This bonding may be chemical bonding including hydrogen bonding.

[0041] That is, the heat fusion portion may refer to a region where the first chrome plating layer, the heat fusion layer, and the second chrome plating layer are stacked in a thickness direction.

[0042] The hot melt layer may include a substrate-free layer containing PP-MAH.

[0043] The area of ​​the first chrome plating layer may correspond to or be greater than the area of ​​the hot-melt layer.

[0044] The PP-MAH may be disposed on the first chrome plating layer formed on the surface #1 by insert molding.

[0045] The first chrome plating layer can serve as a base material for the PP-MAH in the hot melt layer.

[0046] The area of ​​the second chrome plating layer may correspond to or be larger than the area of ​​the hot-melt layer.

[0047] The PP-MAH may be disposed on the second chrome plating layer formed on the surface #2 by insert molding.

[0048] The second chrome plating layer can serve as a base material for the PP-MAH in the hot melt layer.

[0049] The stopper may have a central protrusion protruding toward the liquid injection port from a position facing the liquid injection port.

[0050] The central protrusion is insertable into the liquid injection port.

[0051] The central protrusion may contact an inner peripheral surface of a battery can or a cover defining the liquid injection port so that the center of the stopper and the center of the liquid injection port are aligned.

[0052] The central protrusion may penetrate the liquid injection port in a depth direction.

[0053] The central protrusion is inserted only to a predetermined depth of the liquid injection port.

[0054] The heat fusion portion may be provided between the central protrusion and an inner peripheral surface of the battery can or the cover defined by the liquid injection port.

[0055] The heat fusion portion may not be provided between the central protrusion and the inner peripheral surface of the battery can or the cover defined by the liquid injection port.

[0056] The central protrusion may not be inserted into the liquid injection port.

[0057] A recessed portion for accommodating the plug may be provided around the liquid injection port.

[0058] A protrusion that defines the recessed portion may be provided around the recessed portion.

[0059] An outer peripheral surface of the stopper may contact an inner peripheral surface of the recessed portion so that a center of the stopper and a center of the liquid injection port are aligned.

[0060] The axially outer surface of the plug received in the recessed portion may correspond to the surface of the protruding portion in the axial direction, or may be disposed further inward in the axial direction.

[0061] Surface #1 includes a surface #1-1 facing outward in the axial direction of the battery cell, and surface #2 includes a surface #2-1 facing surface #1-1 and facing inward in the axial direction of the battery cell.

[0062] Surface #1-1 may be the outer surface of the bottom or lid of the battery can, and surface #2-1 may be the bottom surface of the plug.

[0063] A heat fusion portion may be provided between surface #1-1 and surface #2-1.

[0064] Surface #1 may include surface #1-2 facing inward in the radial direction of the battery cell, and surface #2 may include surface #2-2 facing surface #1-2 and facing outward in the radial direction.

[0065] Surface #1-2 may be the inner peripheral surface of the bottom or lid of the battery can defining the liquid injection port, and surface #2-2 may be the outer peripheral surface of the central protrusion of the plug.

[0066] Surface #1-2 may be the inner peripheral surface of the protrusion of the bottom or lid of the battery can defining the recessed portion, and surface #2-2 may be the outer peripheral surface of the plug.

[0067] A heat fusion portion may be provided between surface #1-2 and surface #2-2.

[0068] The heat fusion portion may not be provided between the surface #1-2 and the surface #2-2.

[0069] The plug and the battery can or cover joined to the plug by the heat-fused portion can be electrically connected.

[0070] The electrical connection path may include a contact area between surface #1 and surface #2 where no heat fusion portion is provided.

[0071] Its electrical connection path may include a heat-fused portion including a substrate-free heat-fused layer.

[0072] The first electrode terminal may be installed at a central portion of the bottom.

[0073] The first electrode terminal may be installed at the bottom while being insulated from the bottom.

[0074] The bottom portion around the first electrode terminal may constitute the second electrode terminal, and the side wall portion connected to the bottom portion may also constitute the second electrode terminal.

[0075] An electrode assembly having a first electrode and a second electrode may be housed in the battery can.

[0076] The electrode assembly may be a jellyroll type in which a first electrode and a second electrode are separated by a separator and wound together.

[0077] The electrode assembly may be housed within the battery can while being axially aligned with the battery can.

[0078] The contact of the first electrode may be located at one axial end of the electrode assembly.

[0079] The tab may be a portion of the metal foil of the first electrode extending toward one axial end of the electrode assembly.

[0080] The joints of the first electrode may be bent in the radial direction to overlap each other, thereby forming a plane substantially perpendicular to the axial direction.

[0081] A current collector plate may be connected to the tab of the first electrode.

[0082] The current collector plate may be connected to the first electrode terminal.

[0083] Therefore, the first electrode terminal may have a first polarity.

[0084] The tap of the second electrode may be located at the other axial end of the electrode assembly.

[0085] The tab may be a portion of the metal foil of the second electrode extending toward the other axial end of the electrode assembly.

[0086] The joints of the second electrode may be bent in a radial direction to overlap each other, thereby forming a plane substantially perpendicular to the axial direction.

[0087] The contact of the second electrode may be disposed at the open end.

[0088] The cover may be connected to the contact of the second electrode.

[0089] The cover may include an electrode connecting portion thermally coupled to the second electrode tap of the electrode assembly.

[0090] The electrode connecting portion may be recessed axially inward from the cover surface.

[0091] The electrode connecting portion may extend flatly in the radial direction.

[0092] The electrode connecting portion may be connected to the second electrode tab of the electrode assembly by thermal bonding.

[0093] The thermal bonding of the cover to the second electrode terminal may be achieved by a process selected from welding, brazing and soldering.

[0094] Therefore, the cover, the side wall portion connected to the cover, and the bottom portion connected to the side wall portion may have the second polarity.

[0095] The thermally coupled portion of the electrode connecting portion and the second electrode tab may be disposed along an extending direction of the electrode connecting portion.

[0096] The thermally bonded portion may be a welding portion W formed by scanning a laser across the surface of the electrode connection portion in a radial direction.

[0097] The liquid injection port may be provided in a central portion of the cover.

[0098] The liquid injection port may be aligned with the core hollow portion of the electrode assembly.

[0099] The electrode connection portion may extend radially around the liquid injection port.

[0100] The cover may have a bottom surface extending axially outward from the electrode connecting portion.

[0101] The bottom surface may be disposed further outward than a joining region M of the cover and the battery can in the axial direction.

[0102] The axially outer surface of the plug may be disposed axially further inwardly than the bottom surface.

[0103] The liquid injection port may be provided on a protrusion that protrudes further in the axial direction than the electrode connecting portion.

[0104] The cover may be provided with two or more electrode connection portions that are recessed toward the inside of the battery can and extend in a radial direction. Four electrode connection portions may be provided.

[0105] The welded portion may be formed by irradiating a laser beam onto the surface of the electrode connecting portion along the extending direction of the electrode connecting portion.

[0106] In addition, the present invention provides a method for manufacturing a battery cell using the sealing structure of the liquid injection port.

[0107] The first embodiment of the manufacturing method includes: a battery can preparation step, an electrode assembly preparation step, a cover preparation step, a plug preparation step, an electrode assembly accommodating step, a first electrode terminal connecting step, a cover connecting step, a liquid injection step and a liquid injection port closing step.

[0108] The battery can preparation step includes preparing a battery can having a side wall portion, a bottom connected to one axial end of the side wall portion, and an open end disposed at the other axial end of the side wall portion, and sealing and insulating a first electrode terminal at the center of the bottom.

[0109] The electrode assembly preparation step includes: manufacturing an electrode assembly including a first electrode and a second electrode, wherein a connector 21 of the first electrode and a connector 22 of the second electrode are respectively arranged on both sides of the axial direction.

[0110] The electrode assembly preparing step may include bending a joint of the first electrode in a radial direction, and thermally bonding the current collector plate to the bent portion.

[0111] The cover preparation step includes manufacturing a cover including an electrode connection portion electrically connected to the contact of the second electrode and a liquid injection port provided at a central portion of the electrode connection portion.

[0112] The cover preparation step may include chromating the surface surrounding the liquid injection port.

[0113] The plug preparation steps include: performing chromate treatment on the surface of the plug; and insert-molding a hot-melt layer including PP-MAH into the chrome-plated layer formed by the chromate treatment.

[0114] The electrode assembly accommodating step includes, after the battery can preparing step and the electrode assembly preparing step, accommodating the electrode assembly in the battery can in such a manner that the tab of the first electrode faces the bottom of the battery can.

[0115] The first electrode terminal connecting step includes connecting a tab of the first electrode or a current collector plate connected to the tab to the first electrode terminal after the electrode assembly accommodating step.

[0116] The cover connecting step includes: covering the open end of the battery can with the cover so that the electrode connecting part is in close contact with the connector of the second electrode; electrically connecting the electrode connecting part to the connector of the second electrode by bonding; and bonding the outer periphery of the cover to the periphery of the open end of the battery can.

[0117] The liquid injection step includes injecting an electrolyte into the battery can through a liquid injection port after the first electrode terminal connecting step and the lid fixing step.

[0118] The liquid injection port closing step includes: covering the liquid injection port with a plug, and heating the hot melt layer using a hot melt device to form a chemical bond with a hydrogen bond between the PP-MAH and the chrome plating layer.

[0119] The second embodiment of the manufacturing method includes a battery can preparation step, an electrode assembly preparation step, a cover preparation step, a plug preparation step, a second electrode connection step, an electrode assembly accommodation and cover insertion step, a first electrode terminal connection and cover fixing step, a liquid injection step and a liquid injection port closing step.

[0120] The battery can preparation step includes preparing a battery can having a side wall portion, a bottom connected to one axial end of the side wall portion, and an open end disposed at the other axial end of the side wall portion, and sealing and insulating a first electrode terminal at the center of the bottom.

[0121] The electrode assembly preparation step includes: manufacturing an electrode assembly including a first electrode and a second electrode, wherein a connector 21 of the first electrode and a connector 22 of the second electrode are respectively arranged on both sides of the axial direction.

[0122] The electrode assembly preparing step may include bending a joint of the first electrode in a radial direction, and thermally bonding the current collector plate to the bent portion.

[0123] The cover preparation step includes manufacturing a cover including an electrode connection portion electrically connected to the contact of the second electrode and a liquid injection port provided at a central portion of the electrode connection portion.

[0124] The cover preparation step may include chromating the surface surrounding the liquid injection port.

[0125] The plug preparation steps include: performing chromate treatment on the surface of the plug; and injecting a hot melt layer insert containing PP-MAH into the chrome-plated layer formed by the chromate treatment.

[0126] The second electrode connecting step includes electrically connecting the electrode connecting portion of the cover to the connector of the second electrode by bonding after the electrode assembly preparing step and the cover preparing step.

[0127] The electrode assembly accommodating and cover inserting step includes: after the battery can preparation step and the second electrode connecting step, accommodating the electrode assembly in the battery can in such a way that the joint of the first electrode faces the bottom of the battery can, and inserting the cover into the open end of the battery can.

[0128] The first electrode terminal connecting and cover fixing step includes connecting the first electrode tab to the first electrode terminal and coupling the outer periphery of the cover to the periphery of the open end of the battery can after the electrode assembly accommodating and cover inserting steps.

[0129] The liquid injection step includes injecting an electrolyte into the battery can through a liquid injection port after the first electrode terminal connecting step and the lid fixing step.

[0130] The liquid injection port closing step includes: covering the liquid injection port with a plug, and heating the hot melt layer using a hot melt device to form a chemical bond with a hydrogen bond between the PP-MAH and the chrome plating layer.

[0131] The present invention provides a high energy density battery pack comprising the battery core.

[0132] The present invention provides a vehicle equipped with a high energy density battery pack, thereby reducing the volume or load occupied by the battery pack.

[0133] Beneficial Effects

[0134] According to the present invention, since the liquid injection port is not closed by a rivet that applies a plastic deformation load or a metal ball that applies a forced press-fit load, there is no risk of deformation of the cover or damage to the electrodes in the battery can, and since there is no need for a space for inserting rivets for riveting or a space for the metal ball to press into the battery cell, more available internal volume is ensured for the battery cell, thereby improving the energy density of the battery cell.

[0135] According to the present invention, since the liquid injection port can be closed at a lower temperature than high temperature bonding (such as welding) and medium temperature bonding (such as brazing or soldering), it is not necessary to make the liquid injection port protrude further outward than the cover or the battery can in order to prevent the heat applied when closing the liquid injection port from being transferred to the electrolyte or the electrode assembly. That is, the cover adopting this liquid injection port structure can be designed to be flat, thereby ensuring that the battery can has more internal volume while meeting the same specifications.

[0136] According to the present invention, since no external force is applied to cause deformation of the cover or the battery can, and the liquid injection port is closed by combining the plug with the cover at a temperature lower than that of soft soldering, there is no risk of deformation of the cover, damage or deformation of the electrode assembly and related components contained in the battery can, or deterioration or fire of the electrolyte.

[0137] According to the present invention, in the bonding of two metals, since the heat-melting layer is chemically bonded to the surfaces of the cap and the plug of the metal material through hydrogen bonding, the sealing strength is excellent.

[0138] According to the present invention, since the hot-melt layer is formed in the stopper by insert molding, there is no need to prepare a separate hot-melt film, thereby simplifying the sealing operation.

[0139] According to the present invention, since the PP-MAH (polypropylene-maleic anhydride) of the hot-melt layer is chemically bonded to the chrome-plated layers of the battery can and the plug, sealing is ensured and the possibility of electrolyte leakage can be greatly reduced.

[0140] In addition to the above beneficial effects, specific effects of the present invention will be further elaborated while describing the specific details of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0141] Figures 1 to 6 It is a diagram showing a method of sealing a liquid injection port of an electrolyte solution of a conventional battery can.

[0142] Figures 7 to 9 It is a diagram showing a closing structure and a closing method of a liquid injection port of an electrolyte solution of a battery can according to a first embodiment of the present invention.

[0143] Fig.10 It is a diagram showing the chemical bonding structure of chromium oxide and PP-MAH in the chromium plating layer.

[0144] Fig.11 and Fig.12 It is a figure which shows the manufacturing process of the electrolyte plug.

[0145] Fig.13 and Fig.14 1 is a diagram showing a closing structure of a liquid injection port of an electrolyte solution of a battery can according to a second embodiment of the present invention.

[0146] Fig.15 and Fig.16 1 is a diagram showing a closing structure of a liquid injection port of an electrolyte solution of a battery can according to a third embodiment of the present invention.

[0147] Fig.17 1 is a diagram showing a closing structure of a liquid injection port of an electrolyte solution of a battery can according to a fourth embodiment of the present invention.

[0148] Fig.18 is a perspective view of a battery cell according to this embodiment.

[0149] Fig.19 and Fig. 20 are perspective views showing before and after manufacturing a first electrode, a second electrode, and a separator stack of an electrode assembly to be housed in a battery can, respectively, Fig.21 yes Fig. 20 Floor plan of the structure.

[0150] Fig. 22 and Fig.23 is through Fig. 20 and Fig.21 A perspective view and a side view of an electrode assembly manufactured by winding a laminate into a core-wound type.

[0151] Fig.24 and Fig.25 is a perspective view of an electrode assembly with a current collector plate coupled to an upper portion thereof and without a current collector plate coupled to a lower portion thereof.

[0152] Fig.26 It shows that Fig.24 and Fig.25 A cross-sectional view of a process of housing an electrode assembly into a battery can.

[0153] Fig. 27 is a cross-sectional view illustrating a process of welding a first electrode terminal and a current collector plate.

[0154] Fig.28 The figure shows the process of covering the open end of the battery can with a cover.

[0155] Fig.29 is a cross-sectional view showing a process of combining an electrode connection portion of a cover with a tab of a second electrode of an electrode assembly, and combining a periphery of the cover with an open end of a battery can.

[0156] Fig.30 It is a diagram showing a process of closing the liquid injection port with a plug.

[0157] Figure 31 to Figure 33 4 are an upper perspective view, a lower perspective view, and a top view of a cover according to a fifth embodiment of the present invention, respectively.

[0158] Fig.34 and Fig.35 yes Fig.33 A cross-sectional view of the corresponding part.

[0159] Fig.36 is a perspective view showing the combination of a cover and a lower portion of an electrode assembly.

[0160] Fig.37 and Fig.38 Flowcharts respectively show methods for manufacturing a battery cell using a liquid injection port sealing structure according to a first embodiment and a second embodiment of the present invention.

[0161] Fig.39 and Fig.40 A battery pack using the battery cell according to the embodiment and a vehicle equipped with the battery pack are respectively shown.

[0162] [Explanation of Reference Numerals]

[0163] 10: Battery can 11: Side wall 12: Bottom 13: Positive terminal (first electrode terminal) 14: Terminal gasket 15: Negative terminal (second electrode terminal) 19: Insulator 20: Electrode assembly 21: First electrode 22: Second electrode 23: Metal foil 24: Active material layer 25: Coated area 26: Uncoated area 27: Notched joint 28: Separator 31: Current collector plate 32: Terminal connection portion 33: Ring portion 34: Electrode connection portion 40: Cover 41: Electrode connection portion W: Welding portion 42: Liquid injection port 43: Protrusion 44: Base surface 45: Press-fit outer wall M: Bonding area 46: Chrome plating layer (first) 47: Recess 50: Plug 51: Central protrusion 53: Chrome plating layer (second) 55: PP-MAH (hot melt layer) 58: Rivet 59: Ball 60: Hot melt device 70: Battery pack 71: Housing 72: Battery cell 80: Vehicle DETAILED DESCRIPTION

[0164] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0165] The present invention is not limited to the embodiments disclosed below, and various changes can be applied and can be implemented in various different forms. The embodiments provided here are only used to make the disclosure of the present invention complete and fully convey the scope of the invention to those skilled in the art. Therefore, the present invention is not limited to the embodiments disclosed below, and it should be understood that the present invention includes all changes and equivalents covered within the technical spirit and scope of the present invention, as well as the replacement or addition of the configuration of one embodiment with the configuration of another embodiment.

[0166] The accompanying drawings are only for the convenience of understanding the embodiments disclosed herein. It should be understood that the technical ideas disclosed herein are not limited by the accompanying drawings, and all changes, equivalents and substitutions within the spirit and technical scope of the present invention are covered. In the accompanying drawings, although the size or thickness of the components may be exaggeratedly enlarged or reduced for the convenience of understanding, this should not be interpreted as limiting the scope of protection of the present invention.

[0167] The terms used herein are only used to describe specific embodiments or examples and are not intended to limit the present invention. In addition, unless the context clearly indicates otherwise, expressions in the singular include expressions in the plural. Here, terms such as "including" and "consisting of" are intended to indicate that the features, numbers, steps, operations, components, parts, or combinations thereof described in the specification exist. That is, it should be understood that terms such as "including" and "consisting of" used herein should not exclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0168] Although terms including ordinal numbers such as "first" and "second" may be used to describe various components, the components are not limited by these terms. These terms are only used to distinguish one component from another.

[0169] It should be understood that when an element is referred to as being "connected" to another element, the element may be directly connected to the other element, or there may be an intervening element in between. On the other hand, when an element is referred to as being "directly connected" to another element, it should be understood that there is no intervening element in between.

[0170] When an element is referred to as being 'on' or 'under' another element, it should be understood that intervening elements may exist and the element may be directly on or under the other element.

[0171] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant field, and unless explicitly defined herein, terms such as those defined in commonly used dictionaries should not be interpreted in an idealized or overly formal sense.

[0172] In the description of the implementation scheme, "axial" refers to "the direction in which the axis surrounding the center of the core-wound electrode assembly extends", "radial" refers to "the direction toward (centripetal) or away from (centrifugal) the axis", and "circumferential" refers to "the direction around the axis".

[0173] The width direction of the electrode assembly in the unfolded state corresponds to the axial direction of the winding core. The length direction of the electrode assembly in the unfolded state corresponds to the circumferential direction of the winding core.

[0174] [First embodiment]

[0175] First, refer to Figures 7 to 12 The sealing structure of the liquid injection port according to the first embodiment includes: a battery can 10 or a cover 40 made of a metal material and provided with a liquid injection port 42 ; and a metal plug 50 covering and sealing the liquid injection port 42 .

[0176] According to this embodiment, the liquid injection port 42 is provided on the cover 40. However, it is apparent that the liquid injection port 42 may also be provided on the battery can 10. In the case of a cylindrical battery can, the liquid injection port 42 may be provided at the central portion of the cover 40 or the central portion of the bottom of the battery can 10.

[0177] The battery can 10 and the cover 40 may be made of aluminum, steel, or an alloy thereof. In addition, the plug 50 may also be made of aluminum, steel, or an alloy thereof. According to this embodiment, aluminum is used as an example of a material for the battery can 10 and the cover 40.

[0178] The battery can 10 may be cylindrical. The battery can 10 may include a hollow circular tubular side wall portion 11 and a bottom 12 connected to one axial end of the side wall portion 11. However, the shape of the battery can 10 of the present invention is not limited thereto, and it is apparent that a rectangular battery can is also applicable.

[0179] The cover 40 may cover the open end provided at the other axial end of the battery can 10. The cover 40 may be circular. However, the shape of the cover 40 of the present invention is not limited thereto, and a polygonal cover is also applicable.

[0180] The edge of the cover 40 may be coupled thereto while being in contact with the circumference of the other axial end of the side wall portion 11 of the battery can 10 .

[0181] The cross section of the plug covering the liquid injection port 42 surrounds and is larger than the cross section of the liquid injection port 42. In this embodiment, a circular liquid injection port 42 and a circular plate-shaped plug 50 having a radius larger than that of the liquid injection port 42 are taken as an example.

[0182] By the chromate surface treatment, a first chrome plating layer 46 is formed on the outer surface of the cover 40 provided with the liquid injection port 42 and the inner peripheral surface of the hole of the cover 40 defining the liquid injection port 42 .

[0183] A central protrusion 51 is provided at a central portion of the inner surface (bottom surface) of the stopper 50 , which corresponds to the inner diameter of the liquid injection port 42 and protrudes toward the liquid injection port 42 .

[0184] When the stopper 50 covers the liquid injection port 42 , the central protrusion 51 passes through the liquid injection port 42 and protrudes further inward than the inner surface of the cap 40 .

[0185] The second chrome plating layer 53 is formed on the inner surface (bottom surface) of the plug 50 and the outer peripheral surface of the central protrusion 51 by the chromate surface treatment.

[0186] When a chrome plating layer is formed on the cover 40 or the plug 50 made of aluminum, as Fig.10 As shown, the metal-chromium oxide will coat the aluminum surface.

[0187] When the liquid injection port 42 is covered with the plug 50 , the outer surface of the cover 40 formed with the first chrome plating layer 46 and the inner peripheral surface of the liquid injection port 42 are in contact with the bottom surface of the plug 50 formed with the second chrome plating layer 53 and the outer peripheral surface of the central protrusion 51 , respectively.

[0188] A heat-melting layer 55 is interposed between the first chrome plating layer 46 and the second chrome plating layer 53 which are in contact with each other.

[0189] The hot melt layer 55 may include a substrate-free layer including PP-MAH.

[0190] With the heat-melting layer 55 inserted, the surface of the plug 50 is pressed and heated using the heat-melting device 60. The heating temperature may be lower than the thermal decomposition temperature of the electrolyte injected into the battery can 10.

[0191] In this embodiment, the thermal decomposition temperature of the electrolyte is about 200 degrees Celsius, and the heating temperature of the hot-melt layer 55 may be lower than 200 degrees Celsius.

[0192] Results, such as Fig.10 As shown, chemical bonds including hydrogen bonds are generated between PP-MAH and the chrome-plated layer of the heat-melting layer 55, and a heat-fused portion is formed. That is, when the sealing structure of the liquid injection port according to this embodiment is adopted, a strong chemical bond is generated between the plug and the cap without applying a strong external force and high-temperature heat to the cap 40 and the plug 50, thereby reliably sealing the liquid injection port.

[0193] For process convenience, PP-MAH may be provided by insert injection molding to be pre-laminated on the bottom surface of the stopper 50 , thereby forming the hot melt layer 55 .

[0194] To achieve this, Fig.11 As shown, a second chrome plating layer 53 may be formed on the bottom surface of the stopper 50 and the outer peripheral surface of the central protrusion 51 .

[0195] In addition, if Fig.12 As shown, PP-MAH may be disposed on the bottom surface of the plug 50 coated with the second chrome plating layer 53 and the outer peripheral surface of the central protrusion 51 by insert molding to form a hot melt layer 55 .

[0196] The hot melt layer containing PP-MAH itself is a layer without a substrate. However, since the second chrome plating layer 53 acts as a substrate for PP-MAH, the hot melt layer can be laminated on the plug 50 very stably.

[0197] Therefore, if Figure 7 As shown, the heat-melting layer 55 may be provided so as to be integrally laminated on the bottom surface of the plug 50. As a result, the liquid injection port closing work can be simply completed by covering the liquid injection port 42 with the plug 50 having the heat-melting layer 55 thereon, and then pressing and heating the plug 50 with the heat-melting device 60 so that the heat-melting layer 55 is thermally bonded to the chrome-plated layer in contact with the heat-melting layer 55 through chemical bonds including hydrogen bonds.

[0198] The first embodiment uses the second chrome-plated layer 53 as a base material to laminate the hot-melt layer 55 on the second chrome-plated layer 53 of the plug 50 as an example. Since the plug 50 does not participate in the battery cell manufacturing process before the liquid injection port 42 is closed, there is no risk of damage to the hot-melt layer 55 during the manufacturing process, thereby facilitating the handling of parts.

[0199] However, it is obvious that the heat-melting layer 55 can be stacked using the first chrome-plated layer 46 of the battery can 10 as a base material. When the plug 50 is pressed and heated by the hot-melting device 60 to form a heat-fused portion, considering the heat conduction path, the heat first reaches the area between the second chrome-plated layer 53 and the heat-melting layer 55, and then reaches the area between the heat-melting layer 55 and the first chrome-plated layer 46. Therefore, when the heat-melting layer 55 stacked using the first chrome-plated layer 46 of the battery can 10 as a base material is heat-melted, it is advantageous that the chemical bond between the second chrome-plated layer 53 and the heat-melting layer 55 and the chemical bond between the heat-melting layer 55 and the first chrome-plated layer 46 can be established in a more balanced manner.

[0200] According to the first embodiment, the heat-fusible layer 55 is first stacked on the plug 50. Since the heat-fusible layer 55 stacked on the plug 50 is formed by insert molding in a mold, the alignment of the second chrome plating layer 53 and the heat-fusible layer 55 can be accurately achieved.

[0201] Reference Fig. 9 The outer end of the first chrome plating layer 46 in the radial direction provided on the outer surface of the cover 40 is applied in such a manner that the outer end of the first chrome plating layer 46 extends radially further outward than the outer end of the plug 50. Therefore, the risk of missing the first chrome plating layer 46 of the battery can 10 required for the heat-fused portion in some areas of the outer surface of the battery can 10 due to manufacturing errors of the plug 50 or the battery can 10 or assembly errors in the closing process can be prevented in advance.

[0202] Likewise, the central protrusion 51 of the stopper 50 may be manufactured to extend longer than the depth of the liquid injection port 42. Therefore, the risk of missing the second chrome plating layer 53 and the heat-melting layer 55 required for forming the heat-melted portion in some areas of the inner peripheral surface of the liquid injection port 42 due to a manufacturing error of the stopper 50 or the battery can 10 or an assembly error in the sealing process can be prevented in advance.

[0203] According to the sealing structure of the liquid injection port of the above-mentioned battery can, since the liquid injection port is sealed at the temperature required for hot melting when closing the liquid injection port, there is no possibility of electrolyte deterioration or fire, and since hot melting is performed using a component in which the PP-MAH insert is injection molded onto the plug, the sealing process is simple and reliable sealing is achieved through chemical bonding between the PP-MAH and the chrome plating layer.

[0204] [Second Embodiment]

[0205] Below, refer to Fig.13 and Fig.14 The sealing structure of the liquid injection port according to the second embodiment is described. When describing the second embodiment, the description overlapping with the first embodiment is not repeated. Therefore, the content not specifically described in the description of one embodiment can be understood from the content of other embodiments. In addition, it should be understood that the configuration of one embodiment can also be replaced, added, omitted or combined with the configuration of another embodiment.

[0206] The sealing structure of the liquid injection port according to the second embodiment is different from that of the first embodiment in that: the first chrome plating layer 46 is not provided on the inner peripheral surface of the liquid injection port 42; the second chrome plating layer 53 is not provided on the outer peripheral surface of the central protrusion 51 of the plug 50; and the hot melt layer 55 is not inserted between the inner peripheral surface of the liquid injection port 42 and the outer peripheral surface of the central protrusion 51.

[0207] In order to form a heat-fused portion between the inner peripheral surface of the liquid injection port 42 and the outer peripheral surface of the central protrusion 51, appropriate contact is required between the heat-fused layer 55 and the chrome-plated layer. However, since the plug 50 is assembled to the cap 40 in the axial direction, there is a possibility that due to manufacturing errors or assembly tolerances of the components, appropriate contact between the heat-fused layer 55 and the chrome-plated layer required for forming a heat-fused portion between the inner peripheral surface of the liquid injection port 42 and the outer peripheral surface of the central protrusion 51 facing each other in the radial direction cannot be established.

[0208] Therefore, according to the second embodiment, the elements (the first chrome plating layer, the second chrome plating layer and the heat-melting layer) for forming a heat-melting portion between the inner peripheral surface of the liquid injection port 42 and the outer peripheral surface of the central protrusion 51 are omitted, and a sealing structure is constructed in such a way that the central protrusion 51 directly contacts the inner peripheral surface of the liquid injection port 42 as an example.

[0209] The central protrusion 51 can provide a function of aligning the center of the stopper 50 with the center of the liquid injection port 42 . In addition, the outer diameter of the central protrusion 51 can be slightly larger than the inner diameter of the liquid injection port 42 so that the central protrusion 51 is press-fitted into the liquid injection port 42 .

[0210] As a result, there is no need to extend the central protrusion 51 longer than the depth of the liquid injection port 42, and in order to reduce the pressing force and ensure more space within the battery can 10, the length of the central protrusion 51 can be shorter than the depth of the liquid injection port 42, so that the central protrusion 51 is only inserted to a predetermined depth of the liquid injection port 42 in the depth direction.

[0211] Since the cover 40 can function as an electrode, and it is more desirable that the plug 50 can also function as an electrode like the cover, the second embodiment in which the plug 50 is directly in contact with the cover 40 is more advantageous than the first embodiment in which the plug 50 is connected to the cover 40 via a heat-fused portion. Obviously, the heat-fused portion does not electrically insulate the plug 50 from the cover 40.

[0212] Similar to the first embodiment, the hot melt layer 55 of the second embodiment can also use the second chrome plating layer 53 coated on the plug 50 as a base material and be stacked by insert injection molding.

[0213] [Third Embodiment]

[0214] Below, refer to Fig.15 and Fig.16 , a sealing structure of a liquid injection port according to a third embodiment will be described.

[0215] The sealing structure of the liquid injection port according to the third embodiment is different from that of the second embodiment in that a protrusion 43 protruding axially outward is provided on the radially outer side of the liquid injection port 42 of the battery can 10, and the liquid injection port 42 is provided in a recessed portion 47 recessed axially inward from the protrusion 43.

[0216] In the case where the stopper 50 covers the liquid injection port 42 , the height of the axially outer surface of the stopper 50 may correspond to or be lower than the height of the surface of the protrusion 43 .

[0217] As a result, the plug 50 does not protrude from the surface of the cover 40 at all, so that there is no risk of the seal being broken by applying an impact or external force to the portion of the plug 50 protruding from the surface of the cover 40.

[0218] The inner peripheral surface of the protrusion 43 defined by the recess 47 may contact the outer peripheral surface of the stopper 50. As a result, when the liquid injection port 42 is covered with the stopper 50, the inner peripheral surface of the protrusion 43 guides the alignment of the stopper 50 with the liquid injection port 42.

[0219] To achieve this, the upper end of the inner peripheral surface of the protrusion 43 may be provided with a tapered surface whose diameter gradually decreases axially inward from the boundary between the protrusion 43 and the recess 47. When the cover 40 is press-processed to form the protrusion 43 and the recess 47, such a tapered shape may be naturally formed.

[0220] No heat fusion portion is provided between the inner peripheral surface of the protrusion 43 and the outer peripheral surface of the plug 50. Therefore, the inner peripheral surface of the protrusion 43 can directly contact the outer peripheral surface of the plug 50, and the plug 50 can be electrically connected to the protrusion 43.

[0221] Therefore, when the height of the protrusion 43 corresponds to the plug 50, the protrusion 43 and the plug 50 itself function as an electrode terminal protruding from the surface of the cover 40. The polarity of such an electrode terminal may correspond to the polarity of the cover 40.

[0222] According to the third embodiment, the outer diameter of the plug 50 may be manufactured to correspond to or be slightly larger than the inner diameter of the protrusion 43 , so that the plug 50 is configured to be press-fitted into the recess 47 .

[0223] Meanwhile, according to the third embodiment, the structure of the protrusion 43 and the recess 47 guides the alignment of the liquid injection port 42 and the plug 50, so that the central protrusion 51 and the liquid injection port 42 do not need to be repeatedly guided. When the guidance is repeated, if a position error occurs on one side, it may be difficult to insert the plug 50.

[0224] Therefore, in contrast to the second embodiment, according to the third embodiment, the central protrusion 51 protrudes low enough not to be inserted into the liquid injection port 42, so that the central protrusion 51 can be prevented from being inserted into the liquid injection port 42 when the stacked layers (53, 55 and 46) of the heat-fused portion are in contact with each other.

[0225] To achieve this, Fig.16 As shown, the central protrusion 51 may be formed to have a height longer than the sum of the thicknesses of the second chrome plating layer 53 and the heat-melting layer 55 , and to have a height shorter than the sum of the thicknesses of the second chrome plating layer 53 , the heat-melting layer 55 , and the first chrome plating layer 46 .

[0226] Here, the diameter of the central protrusion 51 may be equal to or slightly smaller than the diameter of the liquid injection port 42. In the process of insert-molding the hot melt layer 55 into the stopper 50, the central protrusion 51 may define a radial inner boundary of the hot melt layer 55.

[0227] According to the third embodiment, the plug 50 covering the liquid injection port 42 of the cap 40 can reliably function as an electrode terminal together with the protrusion 43 while being protected by the protrusion 43 and the recessed portion 47 .

[0228] [Fourth Embodiment]

[0229] Below, refer to Fig.17 , a sealing structure of a liquid injection port according to a fourth embodiment will be described.

[0230] The sealing structure of the liquid injection port of the fourth embodiment is different from that of the third embodiment in that a plug 50 without a central protrusion 51 is used.

[0231] In addition, the sealing structure of the liquid injection port of the fourth embodiment is different from that of the third embodiment in that the hot melt layer 55 uses the first chrome plating layer 46 at the bottom of the recessed portion 47 of the cover 40 as a base material and is stacked by insert molding.

[0232] Since the inner circumferential surface of the recess 47 defines the boundary of the outer circumferential surface of the hot melt layer 55 during the insert molding process of the hot melt layer 55 , it is convenient to stack the hot melt layer 55 on the bottom (ie, surface) of the recess 47 of the cover 40 .

[0233] Furthermore, the inner diameter of the second chrome plating layer 53 coated on the bottom surface of the stopper 50 according to the fourth embodiment can be formed to be smaller than the inner diameter of the liquid injection port 42 of the cover 40. As a result, even if there is a manufacturing error or an assembly tolerance, when the bottom surface of the stopper 50 is brought into contact with the heat-melting layer 55 stacked on the cover 40 by covering the liquid injection port 42 with the stopper 50, the second chrome plating layer 53 is surely present on the entire surface of the heat-melting layer 55. Therefore, a heat-melting portion having a sufficient area can be ensured.

[0234] Compared with the third embodiment, according to the fourth embodiment, there is no need to accurately process the height of the central protrusion 51, and since the hot melt layer 55 is stacked on the surface of the recessed portion 47 of the cover 40, there is no risk of damaging the hot melt layer 55 when handling the cover 40 for the battery cell assembly.

[0235] [Fifth Embodiment]

[0236] Below, refer to Figures 18 to 30 , a method for manufacturing a battery cell using the sealing structure of the liquid injection port described above and a structure of the battery cell will be described.

[0237] Fig.18 A cylindrical battery cell is shown.

[0238] The battery cell of this embodiment may be, for example, a cylindrical battery cell having a shape factor ratio (defined as the diameter of the cylindrical battery cell divided by the height, ie, the ratio of the diameter Φ to the height H) greater than about 0.4.

[0239] Here, the form factor refers to the value representing the diameter and height of a cylindrical battery cell. The cylindrical battery cell used in the pressure tester can be, for example, a 46110 cell, a 48750 cell, a 48110 cell, a 48800 cell, or a 46800 cell. In the value representing the form factor, the first two digits represent the diameter of the cell, the next two digits represent the height of the cell, and the last digit 0 represents that the cross section of the cell is circular.

[0240] The battery cell used in the pressure tester may be an approximately cylindrical battery cell with a diameter of about 46 mm, a height of about 110 mm, and a shape factor ratio of 0.418.

[0241] A battery cell according to another embodiment may be a substantially cylindrical battery cell having a diameter of about 48 mm, a height of about 75 mm, and an aspect ratio of 0.640.

[0242] A battery cell according to yet another embodiment may be a substantially cylindrical battery cell having a diameter of about 48 mm, a height of about 110 mm, and an aspect ratio of 0.418.

[0243] A battery cell according to yet another embodiment may be a substantially cylindrical battery cell having a diameter of about 48 mm, a height of about 80 mm, and an aspect ratio of 0.600.

[0244] A battery cell according to another embodiment may be a substantially cylindrical battery cell having a diameter of about 46 mm, a height of about 80 mm, and an aspect ratio of 0.575.

[0245] Obviously, the pressure tester of the present invention can also be applied to battery cells with a shape factor ratio of about 0.4 or less, such as 18650 cells, 21700 cells, etc. For 18650 cells, the diameter is about 18 mm, the height is about 65 mm, and the shape factor ratio is 0.277. For 21700 cells, the diameter is about 21 mm, the height is about 70 mm, and the shape factor ratio is 0.300.

[0246] The battery can 10 includes a cylindrical side wall portion 11 and a bottom 12 connected to one axial end of the side wall portion 11. Here, the term "bottom" is used because the bottom 12 is placed on the ground during the battery cell assembly process, wherein, as shown in FIG. Figures 26 to 30As shown, the open end of the battery can 10 faces upward, and it should be understood that during the actual use process of the battery cell, as shown in FIG. Fig.18 As shown, the bottom portion 12 may be placed on the top portion together with the first electrode terminal 13 .

[0247] The bottom 12 and the side wall portion 11 of the battery can 10 may be integral. For example, the battery can 10 may be made of a stretched steel plate or aluminum plate material. The other end of the side wall portion 11 that is not connected to the bottom 12 in the axial direction may form an open end.

[0248] A hole is formed in the central portion of the bottom 12, and the first electrode terminal 13 can be assembled and connected to the hole. The first electrode terminal 13 can be riveted and fixed to the bottom 12 with a terminal gasket 14 interposed therebetween. The terminal gasket 14 is interposed between the first electrode terminal 13 and the bottom 12 to seal the inside and outside of the battery can 10, thereby preventing leakage of the electrolyte, and electrically insulating the first electrode terminal 13 from the bottom 12.

[0249] However, the connection method between the first electrode terminal 13 and the bottom 12 is not limited thereto. For example, when the structure can seal between the first electrode terminal 13 and the bottom 12 and electrically insulate the first electrode terminal 13 from the bottom 12, various fixing methods such as a bolt-nut fastening method, a glass sealing method, and a thermal bonding method using an insulating film such as a PP (polypropylene) material as a base material of a PP-MAH insulating gasket are also applicable.

[0250] In one embodiment, the first electrode terminal 13 may have a first polarity, and the battery can 10 may have a second polarity. Therefore, the bottom 12 of the battery can 10 and the sidewall portion 11 connected thereto may both have the second polarity.

[0251] In this way, the first electrode terminal 13 and the second electrode terminal 15 can be disposed at one axial end of the battery can 10. Therefore, the bus bar connected to the first electrode terminal 13 and the bus bar connected to the second electrode terminal 15 can be located at one axial end of the battery can 10, that is, the upper part of the battery can 10.

[0252] In one example, the first electrode terminal 13 may be a positive electrode terminal, and the second electrode terminal 15 may be a negative electrode terminal. Obviously, the opposite may also be true.

[0253] The electrode assembly 20 is contained in the battery can 10. The electrode assembly 20 is manufactured by the following steps: Fig.19 As shown, a first electrode 21, a second electrode 22 and a separator 28 having a predetermined width and extending in a length direction are prepared; a laminate is formed by sequentially stacking the first electrode 21, the separator 28, the second electrode 22 and the separator 28; and the laminate is wound into a core wrapped around a mandrel, as shown in FIG. Fig. 20 and Fig.21 shown.

[0254] The first electrode 21 may be an anode, and the second electrode 22 may be a cathode. Obviously, the opposite is also possible.

[0255] The first electrode 21 and the second electrode 22 are manufactured in the form of sheets. The electrode sheet is manufactured by applying an active material layer 24 to the surface of a metal foil 23. The electrode sheet includes a coated area 25 coated with the active material layer 24 and an uncoated area 26 not coated with the active material layer 24. The anode sheet is provided with the uncoated area 26 on one side in the width direction, and the cathode sheet is provided with the uncoated area 26 on the other side in the width direction.

[0256] The uncoated area 26 is exposed or protrudes from the laminate in the width direction. The uncoated area 26 itself functions as an electrode tab.

[0257] Notches may be formed at predetermined intervals on the uncoated region 26 to form a flag-shaped notched joint 27 .

[0258] In this embodiment, the notched joint 27 is shown in the shape of an equilateral trapezoid. However, the notched joint 27 can have various shapes, such as a semicircle, a semi-ellipse, a triangle, a rectangle, a parallelogram, etc.

[0259] Furthermore, in this embodiment, the notched joints 27 arranged in the length direction and having the same width are taken as an example. However, the width of the notched joints may be gradually widened from the core side to the outer peripheral side.

[0260] In addition, in this embodiment, the height of the notched joint 27 gradually increases from the core side to the outer peripheral side. However, the height of the notched joint may be constant or gradually decrease.

[0261] In addition, in this embodiment, the structure in which the notched joint 27 is removed at the predetermined portion of the centripetal end and the distal end of the uncoated region 26 is taken as an example. However, it is obvious that the notched joint may not be removed from the distal end of the uncoated region, and the notched joint may not be removed from the distal end of the uncoated region.

[0262] In the jellyroll type electrode assembly 20, the notched joint 27 may be bent and flattened in the radial direction. The notched joint 27 may be bent radially inward or outward. In this embodiment, as shown in FIG. Fig. 22 and Fig.23 As shown, a structure in which the notched joint 27 is bent radially inward is taken as an example.

[0263] In the process of forming the jellyroll type electrode assembly 20 by winding the laminate, the notched tabs 27 may be bent one by one. Alternatively, after the laminate is wound to form the jellyroll type electrode assembly, the notched tabs 27 may be formed by bending at one time.

[0264] The notched joint 27 of the first electrode 21 and the notched joint 27 of the second electrode 22 bent and overlapped in the radial direction as described above can provide a plane substantially perpendicular to the axial direction at each of the two axial ends of the electrode assembly 20, such as Fig.23 shown.

[0265] like Fig.24 As shown, the current collector plates 31 may be respectively coupled to substantially flat surfaces provided by bending the notched tabs 27 exposed at both axial ends of the electrode assembly 20 .

[0266] The current collector plate 31 may be manufactured by stamping, trimming, punching, and bending a metal sheet.

[0267] Reference Fig.24 The current collector plate 31 includes a terminal connection portion 32 extending radially from the center, an annular portion 33 connecting the distal edge of the terminal connection portion 32 in the circumferential direction, and an electrode connection portion 34 extending centripetally from the annular portion 33 but not connected to the terminal connection portion 32. The center of the terminal connection portion 32 covers at least a portion of the core hollow portion of the electrode assembly 20.

[0268] Before the electrode assembly 20 is inserted into the battery can 10 , the electrode connection portion 34 is bonded to the notched tab 27 of the first electrode 21 of the electrode assembly 20 using a method such as laser welding.

[0269] Unlike this embodiment, for example, in a battery cell having a different structure, the notched tab 27 of the first electrode 21 or the current collector plate 31 may be welded and electrically connected to the bottom 12 of the battery can 10. That is, it should be understood that the fifth embodiment is an example of a battery cell to which the sealing structure of the liquid injection port can be applied. In other words, it should be clearly understood that the sealing structure of the liquid injection port described above is not a technology that can be applied only to the battery cell structure disclosed in the fifth embodiment.

[0270] Reference Fig.25 , the current collector plate may not be connected to the notched tab 27 of the second electrode 22 of the electrode assembly 20. The notched tab 27 may be bonded and electrically connected to the cover 40 by direct welding or the like, which will be described later.

[0271] like Fig.26 and Fig. 27 As shown, the electrode assembly 20 is housed in the battery can 10 with the current collector plate 31 aligned with and facing the bottom 12 of the battery can 10. Here, the insulator 19 is interposed between the current collector plate 31 and the bottom 12 of the battery can 10 to electrically insulate the first current collector plate 31 from the bottom 12.

[0272] In addition, the terminal connection portion 32 of the current collector plate 31 is combined with the first electrode terminal 13 fixed to the battery can 10 by resistance welding, ultrasonic welding or laser welding. The welding device for welding the current collector plate 31 and the first electrode terminal 13 can be welded by passing through the core hollow portion of the electrode assembly 20 from the other axial end of the electrode assembly 20 to the back side of the center of the terminal connection portion 32 of the current collector plate 31. Obviously, in addition to the above-mentioned welding method, the current collector plate 31 and the first electrode terminal 13 can also be combined by brazing or soldering.

[0273] Reference Fig.28 and 29 , with the electrode assembly 20 accommodated in the battery can 10 and the first electrode 21 connected to the first electrode terminal 13 , the notched tab 27 of the second electrode 22 may be in direct contact with the cover 40 covering the open end of the battery can 10 .

[0274] When the cover 40 is in close contact with the notched connector 27, as shown in FIG. Fig.29 As shown, the laser may be irradiated onto the surface of the cover 40 in the radial direction using a scanning method to form a radially extending welding portion W. Obviously, the laser may not be irradiated onto a portion where a liquid injection port is provided in the scanning path.

[0275] Therefore, the second electrode 22 is electrically connected to the welded portion W of the notched tab 27 and the cover 40. Obviously, the notched tab 27 and the cover 40 may be combined by a method such as brazing or soldering other than welding.

[0276] Unlike this embodiment, the tab of the second electrode 22 may be bonded and electrically connected to the inner peripheral surface of the side wall portion 11 of the battery can 10 .

[0277] Furthermore, unlike the above-described embodiment, the tap of the second electrode 22 may be coupled to the cover 40 or the sidewall portion 11 of the battery can 10 through a current collector plate (not shown).

[0278] In addition, the tab of the second electrode 22 or the current collector plate connected thereto may be bonded and connected to both the inner circumferential surface of the sidewall portion 11 and the cover 40 .

[0279] In addition, a separate second electrode terminal may be provided at the cover 40 , and a tap of the second electrode 22 or the current collector plate 31 may be connected to the second electrode terminal.

[0280] Return to reference Fig.29The edge of the cover 40 is combined with the open end of the side wall portion 11 of the battery can 10 for electrical connection, sealing and fixing. Therefore, the second electrode 22 can be electrically connected to the cover 40 and the battery can 10. The combination between the cover 40 and the battery can 10 can also be electrically connected and sealed using various methods such as welding, brazing and soldering.

[0281] Obviously, unlike this embodiment, the cover 40 may be fixed to the open end of the side wall portion 11 of the battery can 10 using a compression sealing method such as crimping. It should be understood that even with this structure, the sealing structure of the liquid injection port described above is still applicable.

[0282] High temperature heat may be generated in the process of welding the cover 40 and the side wall portion 11. If an electrolyte exists in the battery can 10 during the welding process, the electrolyte may be denatured or ignite due to the high temperature heat generated in the welding process.

[0283] Therefore, after the processing of the welding portion W and the bonding area M that generate high temperature heat is completed, the electrolyte can be injected through the liquid injection port 42.

[0284] The liquid injection port 42 may be disposed at a position aligned with the core hollow portion of the electrode assembly 20. As a result, the injected electrolyte may penetrate deeply into the hollow core of the electrode assembly 20 and may be smoothly infiltrated.

[0285] After the liquid injection is completed, the liquid injection port 42 can be covered with a plug 50, and the plug 50 can be pressed and heated using the aforementioned hot melt device 60, and the hot melt layer is heated to form a Fig.30 Heat fused section shown.

[0286] Below, refer to Figure 31 to Figure 35 , the structure of the cover 40 applied to the battery cell of the fifth embodiment will be described in detail.

[0287] The cover 40 may be made of a circular metal sheet. The cover 40 has an electrode connection portion 41 that is recessed in a direction corresponding to the axial direction of the battery cell 72. The electrode connection portion 41 may be formed by molding a metal sheet using a press.

[0288] The bottom surface of the electrode connection part 41 is in close contact with and combined with the notched joint 27 of the second electrode 22 of the electrode assembly 20. The thickness of the electrode connection part 41 manufactured by press-processing the metal sheet is slightly thinner than the thickness of the metal sheet. Therefore, when the laser is irradiated onto the surface of the electrode connection part 41, the local heat generated by the laser can melt and combine the surface of the notched joint 27 in contact with the electrode connection part 41 and its bottom surface.

[0289] A plurality of electrode connection parts 41 may be provided. The fifth embodiment shows a structure in which four electrode connection parts 41 are radially arranged at equal intervals of about 90 degrees in the circumferential direction. The electrode connection parts 41 extend in the radial direction, and the welding part W for combining the electrode connection parts 41 with the notched joint 27 of the second electrode 22 of the electrode assembly 20 may have a welding line shape formed in the radial direction corresponding to the extending direction of the electrode connection parts 41, such as Fig.29 shown.

[0290] According to this embodiment, each of the plurality of electrode connecting portions 41 forms a linear weld W extending in the radial direction.

[0291] The cover 40 is provided with a base surface 44 which contacts the ground when the battery can 10 is placed with the cover 40 of the battery can 10 facing the ground. The base surface 44 is provided at a higher position than the electrode connecting portion 41 and between two adjacent electrode connecting portions 41 in the circumferential direction.

[0292] Therefore, by pressing the base surfaces 44 on both sides of the electrode connecting portion 41 in the circumferential direction with a jig, the electrode connecting portion 41 and the notched joint 27 are brought into close contact with each other, as shown in FIG. Fig.29 As shown, the electrode connection part 41 and the notched joint 27 can be welded by irradiating the laser to the surface of the electrode connection part 41. As a result, the electrode connection part 41 is closely contacted with the notched joint 27 along the length direction of the welding line on both sides of the welding line due to the pressure of the clamp on the electrode connection part 41, so that welding can be reliably performed.

[0293] A pair of electrode connection parts 41 facing each other with respect to the center of the cover 40 are arranged on a straight line passing through the center of the cover 40. Therefore, the welding line of the two electrode connection parts 41 aligned in a straight line can be formed by only one movement of the laser welding machine. For example, assuming that in the cover 40 of the fifth embodiment, the first electrode connection part, the second electrode connection part, the third electrode connection part, and the fourth electrode connection part are sequentially arranged in the circumferential direction, the first electrode connection part and the third electrode connection part can be welded at one time, and the second electrode connection part and the fourth electrode connection part can also be welded at one time.

[0294] In addition, according to this embodiment, even if the base surfaces 44 on both sides of the first electrode connecting portion and the third electrode connecting portion arranged in a straight line relative to the center of the cover 40 are pressed by a clamp, due to the large secondary moment of inertia formed by the concave shapes of the second electrode connecting portion and the fourth electrode connecting portion, the cover 40 can still behave like a rigid body and will not warp or bend despite the pressure of the clamp.

[0295] In this embodiment, by configuring the four electrode connection parts 41 as above, the four electrode connection parts 41 can be welded by two laser scanning tracks.

[0296] When the number of processed electrode connection parts 41 is excessive, the strength of the cover 40 made of the metal sheet may be weakened. In addition, when only two or three electrode connection parts 41 are formed, it is difficult to construct a cross section that ensures a sufficient secondary moment of inertia in the circumferential direction.

[0297] When the four electrode connection parts 41 on the cover 40 are formed into a "+" shape as shown in the figure, the welding process can be accurately and easily performed, the warping resistance and bending resistance of the cover 40 can also be ensured, and the strength of the cover 40 can be prevented from being weakened due to the molding process. That is, while the cover 40 functions as a current collector plate, it is preferred to maintain the strength of the original function of closing the open end of the battery can 10.

[0298] The outer edge of the cover 40 in the radial direction has a shape that can be engaged with the other axial end of the side wall portion 11 of the battery can 10. Therefore, the outer edge of the cover 40 in the radial direction is preferably provided with a rounded outer peripheral surface or inner peripheral surface.

[0299] The cover 40 according to the fifth embodiment has a rim with a circular inner surface, and the electrode connection portion 41 is recessed inwardly from the radial inner side in the axial direction more than the circular inner surface of the rim. The circular inner surface of the cover 40 contacts the axial end surface of the side wall portion 11 of the battery can 10, as shown in FIG. Fig.29 As shown, a joining region M welded by irradiating laser light from the outer peripheral side of the battery can 10 toward the radial inner side can be formed.

[0300] Here, the outer edge of the radially recessed portion for forming the electrode connecting portion 41 constitutes an outer wall. The outer wall may constitute a press-fit outer wall 45 having an outer diameter corresponding to the inner diameter of the battery can 10. As a result, when the cover 40 is assembled to the battery can 10, each press-fit outer wall 45 of the plurality of electrode connecting portions 41 is connected to and press-fitted into the inner peripheral surface of the battery can 10, as shown in FIG. Fig.29 As shown, the cover 40 is guided to be aligned with respect to the center of the battery can 10 .

[0301] According to the fifth embodiment, since the four press-fit outer walls 45 are evenly arranged in the circumferential direction and contact the battery can 10 at certain portions of the circumference of the inner circumferential surface of the battery can 10, the cover 40 can be easily press-fitted to the battery can 10 without requiring a large press-fit force.

[0302] As described above, the cover 40 according to this embodiment is advantageous in that manufacturing is facilitated because the press-fit outer wall 45 is molded simultaneously when the electrode connecting portion 41 is molded.

[0303] In addition, according to the structure of the cover 40, since the laser used to weld the cover 40 and the battery can 10 is irradiated radially, even if the inner surface of the edge of the cover 40 and certain parts of the end of the side wall portion 11 of the battery can 10 are not in close contact with each other due to unexpected errors, there is no risk that the laser will directly irradiate the interior of the battery can 10 and damage the electrode assembly 20.

[0304] According to the fifth embodiment, since the base surface 44 of the cover 40 is axially further outward than the joining area M between the cover 40 and the battery can 10, even if the battery can 10 is turned over and stands upright, the joining area M will not directly contact the ground, thereby facilitating its protection.

[0305] By applying the above-mentioned cover 40, it is not necessary to use a current collector plate to electrically connect the joint of the second electrode 22 to the battery can 10, thereby reducing the number of parts and assembly man-hours, and ensuring more internal volume to improve energy density. In addition, the cover 40 electrically connected to the battery can 10 is directly connected to the metal foil 23 of the second electrode of the electrode assembly 20 through the welding portion W extending in the radial direction, so that the current path is evenly distributed, thereby greatly reducing the internal resistance.

[0306] The liquid injection port 42 is provided at the central portion of the cover 40. The liquid injection port 42 may be provided on the bottom surface of the cover 40, that is, on a protrusion 43 that protrudes slightly upward than the electrode connection portion 41 of the cover 40. The height of the protrusion 43 is set to be lower than the height of the base surface 44, and in the case where the liquid injection port 42 is covered and closed by the stopper 50, the height of the stopper 50 may also be lower than the height of the base surface 44.

[0307] Since the protrusion 43 protrudes higher than the bottom, it is convenient for the hot melt device 60 to enter the plug when the plug 50 is thermally bonded after the electrolyte is injected through the liquid injection port 42. In addition, despite the low temperature, the heat transfer of the hot melt device 60 to the inside of the battery can 10 can be minimized.

[0308] Since the plug 50 is also located below the base surface 44 , no load is directly applied to the plug 50 even if the battery cell stands vertically with the cover 40 touching the ground.

[0309] Meanwhile, the liquid injection port 42 disposed at the center of the cover 40 may be a passage for the equipment for welding the first electrode terminal 13 and the current collector plate 31 of the first electrode 21 to enter and exit. Figure 26 to Figure 29 Different from the above assembly sequence shown in FIG. 1 , when the electrode assembly 20 is placed in the battery can, as shown in FIG. Fig.36 As shown, the cover 40 may be inserted into the battery can 10 in a state where the cover 40 is combined with the tab of the second electrode 22 of the electrode assembly 20 .

[0310] That is to say, Fig.36 As shown, in the case where the current collector plate 31 is combined with the joint of the first electrode 21 of the electrode assembly 20 and the cover 40 is combined with the joint of the second electrode 22, the electrode assembly 20 can be accommodated in the battery can 10. In addition, welding between the current collector plate 31 and the first electrode terminal 13 can be performed through the liquid injection port 42 of the cover 40 and the core hollow portion of the electrode assembly 20.

[0311] [Battery cell manufacturing method]

[0312] Since the cover 40 in the fifth embodiment not only serves as the current collector plate of the second electrode but also has the original function of the cover, the manufacturing method of the cover 40 in the fifth embodiment is different from that of the conventional battery cell provided with the second electrode current collector plate.

[0313] Furthermore, since the cover 40 is provided with the liquid injection port 42 and the liquid injection port 42 can be used as a passage for the combining process of the current collector plate 31 and the first electrode terminal 13 , the manufacturing method of the battery cell can be more diversified.

[0314] First, refer to Fig.37 An embodiment of a method for manufacturing a battery cell is described. This embodiment corresponds to Figures 26 to 30 A method for manufacturing a battery cell.

[0315] The manufacturing method includes: preparing a battery can 10 having a first electrode terminal 13 fixed thereto; and preparing an electrode assembly 20 having a first electrode 21 and a second electrode 22. Here, at one axial end of the electrode assembly 20, the first electrode 21 and the current collector plate 31 may be combined and connected.

[0316] Thereafter, the electrode assembly 20 is inserted into the battery can 10 with the current collector plate facing the bottom 12 of the battery can 10, and the current collector plate 31 of the electrode assembly 20 is coupled to the first electrode terminal 13 fixed to the bottom 12 of the battery can 10 by a method such as welding.

[0317] Thereafter, the open end of the battery can 10 is covered with the cover 40. Here, preferably, the electrode connection portion 41 of the cover 40 and the joint of the second electrode 22 of the electrode assembly 20, which are in close contact with each other, are combined, and then the periphery of the open end of the battery can 10 and the edge of the cover 40 are combined.

[0318] Thereafter, the electrolyte is injected into the battery can 10 through the liquid injection port 42 of the cover 40 .

[0319] Finally, the liquid injection port 42 of the battery can 10 is closed and sealed with the plug 50 using the above-mentioned sealing structure of the liquid injection port.

[0320] According to this manufacturing method, since the cover 40 and the second electrode 22 can be combined and the cover 40 and the battery can 10 can be combined before the electrolyte is injected into the battery can 10, and there is no need to perform a separate collector plate combining operation on the second electrode 22, the electrolyte can be prevented from being affected by the combining heat.

[0321] Next, the manufacturing method disclosed in FIG. 41 is described.

[0322] The manufacturing method includes: preparing a battery can 10 having a first electrode terminal 13 fixed thereto; and preparing an electrode assembly 20 having a first electrode 21 and a second electrode 22. Here, at one axial end of the electrode assembly 20, the first electrode 21 and the current collector plate 31 may be combined and connected. In addition, the electrode connection portion 41 of the cover 40 and the joint of the second electrode 22 may be connected to the other axial end of the electrode assembly 20.

[0323] That is, the cover 40 may be coupled to the second electrode of the electrode assembly before the electrode assembly is housed in the battery can.

[0324] Thereafter, the electrode assembly 20 is inserted into the battery can 10 with the current collector plate facing the bottom 12 of the battery can 10. During this process, the cover 40 covers the open end of the battery can 10.

[0325] Thereafter, the current collector plate 31 of the electrode assembly 20 is coupled to the first electrode terminal 13 fixed to the bottom 12 of the battery can 10 by a method such as welding, and then the periphery of the open end of the battery can 10 is coupled to the edge of the cover 40 .

[0326] Thereafter, the electrolyte is injected into the battery can 10 through the liquid injection port 42 of the cover 40 .

[0327] Finally, the liquid injection port 42 of the battery can 10 is closed and sealed with the plug 50 using the above-mentioned sealing structure of the liquid injection port.

[0328] According to this manufacturing method, there is no need to perform a separate collector plate bonding operation on the second electrode 22. Since the cover 40 and the second electrode 22 can be bonded together as well as the cover 40 and the battery can 10 can be bonded together before the electrolyte is injected into the battery can 10, the electrolyte can be prevented from being affected by the bonding heat. In addition, the assembly equipment can be further simplified by first integrating the cover 40 into the electrode assembly 20 instead of managing the cover 40 separately.

[0329] In this way, when the battery cell is manufactured using the cover 40 provided with the liquid injection port 42, the manufacturing method of the battery cell can be more diversified.

[0330] Furthermore, since neither strong pressure nor high temperature heat is applied to the cover 40 when sealing the liquid injection port 42, there is no risk of the internal structure of the battery can 10 being damaged, denatured, or catching fire due to heat.

[0331] [Battery pack and vehicle]

[0332] Reference Fig.39 The battery cell 72 using the sealing structure of the liquid injection port and / or manufactured by the manufacturing method described above can be accommodated in the housing 71 of the battery pack 70. The battery pack 70 can be constructed using a battery module as an intermediate assembly form, or directly constructed without using a battery module as shown in the figure.

[0333] Since the battery cell 72 itself is relatively large in size, there is no particular difficulty in implementing the battery pack 70 even without using an intermediate structure such as a so-called battery module. In addition, since the second electrode is connected via the cover, the battery cell 72 has a lower internal resistance and a higher energy density. Therefore, the energy density of the battery pack 70 can be achieved to be higher.

[0334] The battery pack 70 with such improved energy density can store the same amount of energy with reduced volume and weight. Fig.40 When the vehicle is used in a vehicle such as the vehicle 80 shown, which uses electricity as an energy source, the vehicle's driving range can be further extended compared to the energy.

[0335] It should be understood that the described embodiments are illustrative and non-restrictive in all aspects, and the scope of the present invention will be indicated by the claims rather than the detailed description described. Moreover, the meaning and scope of the claims described later, as well as all changes and modifications derived from equivalent concepts, should be interpreted as included within the scope of the present invention.

[0336] Although the present invention has been described with reference to the example drawings, it should be understood that the present invention is not limited to the embodiments and drawings disclosed in this specification, and those skilled in the art will recognize that various modifications can be made without departing from the scope and concept of the present invention. In addition, although the operational effects of the configuration according to the present invention are not explicitly described when describing the embodiments of the present invention, it should be recognized that the predictable effects should also be recognized by the configuration.

Claims

1. A battery cell, comprising: A battery can 10, wherein the battery can 10 is made of a metal material; A cover 40, which is made of a metal material and covers the open end of the battery can 10; a liquid injection port 42 , the liquid injection port 42 being disposed at the battery can 10 or at the cover 40 ; A plug 50, which is made of a metal material and covers the liquid injection port 42; as well as A heat-fused portion, the heat-fused portion is interposed between a surface #1 of the battery can 10 or the cover 40 surrounding the liquid injection port 42 and a surface #2 of the plug 50 in contact with the surface #1, and is fused to at least a portion of the surface #1 and the surface #2 in a closed loop shape surrounding the liquid injection port 42, wherein: The heat fusion part comprises: A first chrome plating layer 46, wherein the first chrome plating layer 46 is disposed on the surface #1; A second chrome plating layer 53, the second chrome plating layer 53 is disposed on the surface #2; and The hot-melt layer 55 has two sides that are in contact with the first chrome-plated layer 46 and the second chrome-plated layer 53 , respectively, and includes polypropylene-maleic anhydride PP-MAH that is combined with the first chrome-plated layer 46 and the second chrome-plated layer 53 by heating.

2. The battery cell according to claim 1, wherein: The PP-MAH is disposed on one of the first chrome plating layer 46 disposed on the surface #1 and the second chrome plating layer 53 disposed on the surface #2 by insert molding.

3. The battery cell according to claim 1, wherein: One of the first chrome plating layer 46 and the second chrome plating layer 53 serves as a base material of the PP-MAH of the hot melt layer 55 .

4. The battery cell according to claim 1, wherein: The hot melt layer 55 is a substrate-free layer including the PP-MAH.

5. The battery cell according to claim 1, wherein: The stopper 50 includes a central protrusion 51 inserted into the liquid injection port 42, and The central protrusion 51 contacts the inner peripheral surface of the battery can 10 or the cover 40 defining the liquid injection port 42 so that the center of the stopper 50 and the center of the liquid injection port 42 are aligned.

6. The battery cell according to claim 5, wherein: The central protrusion 51 penetrates the liquid injection port 42 in the depth direction.

7. The battery cell according to claim 5, wherein: The central protrusion 51 is inserted only to a predetermined depth of the liquid injection port 42 .

8. The battery cell according to claim 1, wherein: The stopper 50 includes a central protrusion 51 that protrudes toward the liquid injection port 42 from a position facing the liquid injection port 42 but is not inserted into the liquid injection port 42 .

9. The battery cell according to claim 1, wherein: A recessed portion 47 for accommodating the plug 50 is provided around the liquid injection port 42, and The outer peripheral surface of the stopper 50 contacts the inner peripheral surface of the recessed portion 47 so that the center of the stopper 50 and the center of the liquid injection port 42 are aligned.

10. The battery cell according to claim 1, wherein: A recessed portion 47 for accommodating the plug 50 is provided around the liquid injection port 42. A protrusion 43 is provided around the recessed portion 47 to define the recessed portion 47, and The axial outer surface of the plug 50 received in the recessed portion 47 corresponds to the surface of the protruding portion 43 in the axial direction or is disposed further inward in the axial direction.

11. The battery cell according to claim 1, wherein: The surface #1 includes a surface #1-1 facing outward in the axial direction of the battery cell, The surface #2 includes a surface #2-1 facing the surface #1-1 and facing inward in the axial direction of the battery cell, and The heat fusion portion is provided between the surface #1-1 and the surface #2-1.

12. The battery cell according to claim 11, wherein: The surface #1 includes a surface #1-2 facing inward in the radial direction of the battery cell, The surface #2 includes a surface #2-2 facing the surface #1-2 and outward in the radial direction, and The heat fusion portion is provided between the surface #1-2 and the surface #2-2.

13. The battery cell according to claim 11, wherein: The surface #1 includes a surface #1-2 facing inward in the radial direction of the battery cell, The surface #2 includes a surface #2-2 facing the surface #1-2 and outward in the radial direction, and The heat fusion portion is not provided between the surface #1-2 and the surface #2-2.

14. The battery cell according to claim 1, wherein: The plug 50 is electrically connected to the battery can 10 or the cover 40 coupled to the plug 50 through the heat fusion portion.

15. The battery cell according to claim 1, wherein: The liquid injection port 42 is provided in the cover 40, and The edge of the open end of the battery can 10 is thermally bonded to the edge of the cover 40 .

16. The battery cell according to claim 15, wherein: The battery can 10 and the cover 40 are thermally bonded by a process selected from welding, brazing, and soldering.

17. The battery cell according to claim 15, further comprising: The electrode assembly 20 is contained in the battery can 10 and includes a first electrode 21 and a second electrode 22, wherein the connector of the first electrode 21 and the connector of the second electrode 22 are respectively arranged on both sides of the axial direction. The first electrode terminal 13 is electrically insulated from and fixed to the bottom 12 of the battery can 10 which is arranged opposite to the open end in the axial direction, and The first electrode 21 of the electrode assembly 20 is connected to the first electrode terminal 13 through a current collector plate 31 coupled to a tab of the first electrode 21 .

18. The battery cell according to claim 15, further comprising: The electrode assembly 20 is contained in the battery can 10 and includes a first electrode 21 and a second electrode 22, wherein the connector of the first electrode 21 and the connector of the second electrode 22 are respectively arranged on both sides of the axial direction. The cover 40 includes an electrode connecting portion 41 thermally coupled to a joint of the second electrode 22 of the electrode assembly 20 .

19. The battery cell according to claim 18, wherein: The joint of the cover 40 and the second electrode 22 is thermally bonded by a process selected from welding, brazing and soldering.

20. The battery cell according to claim 18, wherein: The liquid injection port 42 is provided at the central portion of the cover 40, and The electrode connection portion 41 radially extends around the liquid injection port 42 .

21. The battery cell according to claim 18, wherein: The cover 40 includes a base surface 44 extending outwardly from the electrode connecting portion 41 in the axial direction, and The axially outer surface of the plug 50 is disposed more inwardly than the base surface 44 in the axial direction.

22. The battery cell according to claim 18, wherein: The liquid injection port 42 is provided on a protrusion 43 that protrudes further than the electrode connection portion 41 in the axial direction.

23. A method for manufacturing a battery cell, the method comprising the following steps: A battery can preparation step: preparing a battery can 10 having a side wall portion 11, a bottom 12 connected to one axial end of the side wall portion 11, and an open end provided at the other axial end of the side wall portion 11, and sealing and insulating a first electrode terminal 13 at the center of the bottom 12; Electrode assembly preparation step: preparing an electrode assembly 20 including a first electrode 21 and a second electrode 22, wherein a joint of the first electrode 21 and a joint of the second electrode 22 are respectively arranged on two sides of the axial direction; Cover preparation step: preparing a liquid injection port 42 and a cover 40 having a first chrome plating layer 46 around the liquid injection port 42; Plug preparation step: preparing a plug 50 having a second chrome plating layer 53; A first electrode terminal connecting step: after the battery can preparation step and the electrode assembly preparation step, the electrode assembly 20 is housed in the battery can 10 in such a manner that the joint of the first electrode 21 faces the bottom 12 of the battery can 10, and the joint of the first electrode 21 and the first electrode terminal 13 are connected; Second electrode connection step: after the electrode assembly preparation step and the cover preparation step, connecting the cover 40 to the connector of the second electrode 22; A cover fixing step: after the first electrode terminal connecting step, fixing the cover 40 to the battery can 10; a liquid injection step of injecting an electrolyte into the battery can 10 after the first electrode terminal connecting step, the second electrode connecting step, and the lid fixing step; and Liquid injection port closing step: After the liquid injection step and the plug preparation step, the liquid injection port 42 is closed with the plug 50 by heating a hot melt layer interposed between the first chrome plating layer 46 and the second chrome plating layer 53 and containing the PP-MAH to form a heat-fused portion.

24. The battery cell according to claim 23, wherein: In the plug preparation step, the hot melt layer is provided on the second chrome plating layer 53 by insert molding.

25. A battery pack comprising a battery cell according to any one of claims 1 to 22.

26. A vehicle comprising the battery pack according to claim 25.

Images