Battery cell, battery pack comprising same, and vehicle

Abstract

The present invention provides a battery cell comprising: a battery housing provided with a side wall portion, a bottom portion connected to one end portion of the side wall portion in an axial direction, and an opening end portion provided at the other end portion of the side wall portion in the axial direction; an electrode assembly in which first and second electrodes and a separator disposed therebetween are wound around a winding axis, and which is accommodated in the battery housing so that a tab of the second electrode faces the opening end portion; and a lid covering the opening end portion and electrically connected to the second electrode, wherein the lid is provided with an abutment surface coming into contact with inner surface of the side wall portion, and an electrode connecting portion electrically connected to the tab of the second electrode, the abutment surface is inclined with respect to the axial direction so that the length of the circumferential portion in the radial direction increases, the lid is electrically assembled with the battery housing and has a protrusion in which a portion of the side wall portion at the opening end side protrudes outward in the radial direction, and at least part of the abutment surface and at least part of the inner surface of the protrusion are bonded to each other.

Description

Battery cells, battery packs including the same, and automobiles

[0001] The present invention relates to a battery cell, a battery pack including the same, and an automobile.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0195743 filed on December 24, 2024, and all contents disclosed in the document of said Korean patent application are incorporated herein as part of this specification.

[0003]

[0004] Secondary batteries, which possess electrical characteristics such as high energy density and high applicability across product categories, are widely applied not only to portable devices but also to electric vehicles (EVs) and hybrid electric vehicles (HEVs) driven by electric power sources.

[0005] These secondary batteries are attracting attention as a new energy source for improving eco-friendliness and energy efficiency, as they not only have the primary advantage of being able to drastically reduce the use of fossil fuels but also the advantage of not generating any by-products from the use of energy.

[0006] Currently, widely used types of secondary batteries include lithium-ion batteries, lithium-polymer batteries, nickel-cadmium batteries, nickel-hydrogen batteries, and nickel-zinc batteries. The operating voltage of these unit secondary battery cells is approximately 2.5V to 4.5V.

[0007] Therefore, if a higher output voltage is required, a battery module or battery pack is configured by connecting multiple battery cells in series. Additionally, a battery module or battery pack is configured by connecting multiple battery cells in parallel depending on the required charge / discharge capacity. Accordingly, the number of battery cells included in the battery module or battery pack and the electrical connection type can be varied according to at least one of the required output voltage and charge / discharge capacity.

[0008] Cylindrical, prismatic, and pouch-type battery cells are known as types of battery cells. In the case of a cylindrical battery cell, an insulating separator is interposed between a positive plate and a negative plate, and this is wound to form a jelly-roll type electrode assembly, which is then inserted into a battery housing along with an electrolyte to constitute a battery.

[0009] In one embodiment, one side of the battery housing of a cylindrical battery cell may be open, and a lid may be welded to one side of the battery housing. However, if the contact area between the battery housing and the lid is insufficient, the weldability between the battery housing and the lid is poor, leading to problems such as reduced welding strength or increased product defects like electrolyte leakage.

[0010] Recently, seam welding processes are being studied as a method for joining leads and battery housings, instead of forming beads or crimping. This seam welding process involves welding the battery housing and the lead, joining the inner surface of the sidewall of the battery housing with the outer surface of the lead for assembly and welding. Meanwhile, to increase the strength of the seam welding process, the contact area of ​​the joint between the battery housing and the lead must be large, thereby minimizing the gap between the lead and the battery housing.

[0011]

[0012] The present invention was developed to solve the aforementioned problems and aims to provide a welding structure of a battery housing and a lead that maximizes the contact area between the battery housing and the lead, and a battery cell to which the same is applied.

[0013] Specifically, the present invention aims to provide a battery cell with a large contact area between the abutting surface of a lead and the battery housing by forming an abutting surface of the lead by anticipating the degree of deformation of the side wall portion, even though the side wall portion of the battery housing is deformed during the process of pressing the lead into the battery housing.

[0014] Furthermore, the present invention aims to provide a new interference fit shape of a battery housing and a lead that can increase the contact area between the battery housing and the lead and increase welding strength, and a battery cell to which the same is applied.

[0015] In addition, the present invention aims to provide a battery cell in which the reliability of the electrical connection between the electrode assembly and the battery housing is ensured while omitting the current collector when connecting the electrode assembly to the battery housing and the electrode terminal.

[0016] In addition, the present invention aims to provide a battery cell that is economical in terms of manufacturing process and manufacturing cost by eliminating the current collector plate.

[0017] However, the technical problems that the present invention aims to solve are not limited to those described above, and other unmentioned problems will be clearly understood by those skilled in the art from the description of the invention below.

[0018]

[0019] To achieve these objectives, according to one aspect of the present invention, a battery cell of the following embodiment, a battery pack including the same, and a vehicle are provided.

[0020] According to a first embodiment, a battery cell is provided comprising: a battery housing having a side wall portion, a bottom portion connected to one axial end of the side wall portion, and an open end provided at the other axial end of the side wall portion; an electrode assembly in which a first electrode and a second electrode and a separator interposed between them are wound around a winding axis, and the tab of the second electrode is oriented toward the open end; and a lead covering the open end of the battery housing and electrically connected to the second electrode; wherein the lead has a butting surface in contact with the inner circumferential surface of the side wall portion and an electrode connection portion electrically connected to the tab of the second electrode, the butting surface is inclined with respect to the axial direction such that the length of the radial circumferential portion is increased, and the lead is assembled with the battery housing by an interference fit, so that a portion of the side wall portion on the open end side of the battery housing has a protrusion protruding radially outward, and at least a portion of the butting surface and at least a portion of the inner circumferential surface of the protrusion are joined.

[0021] According to the second embodiment, in the first embodiment, there may be substantially no gap between at least a portion of the abutting surface and the inner circumferential surface of the protrusion.

[0022] According to the third embodiment, in any one of the first and second embodiments, the gap between at least a portion of the abutting surface and the inner circumferential surface of the protrusion may be 10 μm or less.

[0023] According to the fourth embodiment, in any one of the first to third embodiments, the protrusion may further include an inclined portion at the end on the open end side in which the length of the radial circumference increases axially outward.

[0024] According to the fifth embodiment, in any one of the first to fourth embodiments, the abutting surface may have an inclined surface with an inclination of 1° to 30° with respect to the axial direction.

[0025] According to the sixth embodiment, in any one of the first to fifth embodiments, the thickness of the abutting surface may be thicker than the thickness of the side wall portion.

[0026] According to the seventh embodiment, in any one of the first to fifth embodiments, the protrusion may be formed by deforming the sidewall portion of the open end of the battery housing as the lead and the battery housing are assembled by press fitting together.

[0027] According to the eighth embodiment, in any one of the first to seventh embodiments, the interference fit amount of the lead may be within the range of 30 μm to 250 μm based on one side.

[0028] According to the ninth embodiment, in any one of the first to eighth embodiments, the insertion depth of the lead into the battery housing may be determined by the electrode connection portion of the lead and the tab connection portion of the second electrode of the electrode assembly accommodated in the battery housing.

[0029] According to the 10th embodiment, in any one of the 1st to 9th embodiments, the lead is provided with a support surface that extends radially flatly from the abutting surface in the radial direction, and the support surface may be connected to the abutting surface through a curved surface provided at the axially inner end of the abutting surface.

[0030] According to the 11th embodiment, in the 10th embodiment, the electrode connection portion is provided at a position that is axially recessed from the radially inner side of the support surface, and the axially inner surface of the electrode connection portion may be positioned further inward in the axial direction than the axially inner end of the curved surface.

[0031] According to the 12th embodiment, in the 11th embodiment, a current collector plate is bonded to the tab of the second electrode and electrically connected, and the electrode connection portion may be bonded to the current collector plate and electrically connected to the tab of the second electrode.

[0032] According to the 13th embodiment, in any one of the 11th to 12th embodiments, the electrode connection portion may be electrically connected by being directly bonded to the tab of the second electrode.

[0033] According to the 14th embodiment, in the 13th embodiment, the joint portion of the electrode connection portion and the tab of the second electrode may be extended in the radial direction.

[0034] According to the 15th embodiment, in any one of the 13th to 14th embodiments, the electrode connection portion and the tab of the second electrode may be joined by a weld formed by a laser irradiated on the surface of the electrode connection portion along the radial direction.

[0035] According to the 16th embodiment, in any one of the 1st to 15th embodiments, a liquid injection port may be provided in the central portion of the electrode connection portion.

[0036] According to the 17th embodiment, in the 16th embodiment, the injection port may be provided on a protrusion that protrudes further axially outward than the electrode connection portion around the injection port.

[0037] According to the 18th embodiment, in any one of the 1st to 16th embodiments, the protrusion may further include a sealing weld portion that is recessed inward in the axial direction and extends flatly in the radial direction.

[0038] According to the 19th embodiment, in any one of the 1st to 18th embodiments, the lead is provided with a support surface that extends radially flatly inward from the butting surface, and a plurality of electrode connections are provided radially inward from the support surface, and each of the plurality of electrode connections may be recessed into the battery housing and extended radially.

[0039] According to the 20th embodiment, in the 19th embodiment, the plurality of electrode connections may be arranged radially with respect to the center of the lead.

[0040] According to the 21st embodiment, in any one of the 19th to 20th embodiments, the electrode connecting portions may be arranged at equal intervals in the circumferential direction.

[0041] According to the 22nd embodiment, in any one of the 19th to 21st embodiments, the electrode connection portion may be provided in three portions spaced 120° apart.

[0042] According to the 23rd embodiment, in any one of the 1st to 22nd embodiments, the lead includes a vent portion, and the vent portion may be provided radially outward from the electrode connection portion.

[0043] According to the 24th embodiment, in the 23rd embodiment, the lead is provided with a support surface that extends radially inward from the butting surface and is flat in the radial direction, the electrode connection portion is provided at a position that is axially recessed from the support surface and the vent portion may be provided on the support surface.

[0044] According to the 25th embodiment, in any one of the 1st to 24th embodiments, the bottom portion of the battery housing is provided with a first electrode terminal that is electrically insulated from and fixed to the bottom portion, and the first electrode of the electrode assembly may be electrically connected to the first electrode terminal.

[0045] According to the 26th embodiment, a battery pack comprising a battery cell according to any one of the 1st to 25th embodiments is provided.

[0046] According to the 27th embodiment, a vehicle comprising a battery pack according to the 26th embodiment is provided.

[0047]

[0048] A battery cell according to one embodiment of the present invention may have excellent welding strength because the contact area between the battery housing and the lead is wide.

[0049] Specifically, in a battery cell according to one embodiment of the present invention, as the battery housing and the lead are press-fitted, the battery housing is deformed according to the shape of the lead, and the shape of the lead is designed to have a small gap with the deformed battery housing, so that the welding strength between the battery housing and the lead can be excellent.

[0050] A battery cell according to one embodiment of the present invention provides a new battery housing and a lead interference fit coupling form, thereby providing a battery cell with a new appearance.

[0051] A battery cell according to one embodiment of the present invention can omit a current collector, thereby ensuring economic efficiency in the manufacturing process and manufacturing costs.

[0052] In a battery cell according to one embodiment of the present invention, leakage of the electrolyte can be prevented by welding the battery housing and the lead. In addition, this has the effect of reducing the occurrence of product defects.

[0053] However, the effects obtainable through the present invention are not limited to those described above, and other unmentioned technical effects will be clearly understood by those skilled in the art from the description of the invention below.

[0054]

[0055] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the aforementioned description; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings.

[0056] FIG. 1 schematically shows a battery housing according to one embodiment of the present invention.

[0057] FIG. 2 schematically shows an exploded perspective view of an electrode assembly according to one embodiment of the present invention.

[0058] FIG. 3 schematically shows a laminate of an electrode assembly according to one embodiment of the present invention.

[0059] FIG. 4 schematically shows an electrode assembly produced by winding a laminate of an electrode assembly according to one embodiment of the present invention into a jelly-roll shape.

[0060] FIG. 5 schematically shows an electrode assembly produced by winding a laminate of an electrode assembly according to one embodiment of the present invention into a jelly-roll shape.

[0061] FIG. 6 schematically illustrates a jelly-roll type electrode assembly according to one embodiment of the present invention, in which a current collector plate is attached to one side and not attached to the other side.

[0062] FIG. 7 schematically illustrates a jelly-roll type electrode assembly according to one embodiment of the present invention, in which a current collector plate is attached to one side and not attached to the other side.

[0063] FIG. 8 schematically illustrates the process of housing an electrode assembly according to one embodiment of the present invention in a battery housing.

[0064] FIG. 9 schematically illustrates the process of welding a first electrode terminal and a current collector plate according to one embodiment of the present invention.

[0065] FIG. 10 schematically illustrates the process of pressing a lead into a battery housing according to one embodiment of the present invention.

[0066] FIG. 11 schematically shows a lead according to one embodiment of the present invention.

[0067] FIG. 12 schematically shows a lead according to one embodiment of the present invention.

[0068] FIG. 13 schematically shows a cross-section of a lead according to one embodiment of the present invention.

[0069] FIG. 14 schematically shows a lead according to one embodiment of the present invention pressed into a battery housing.

[0070] FIG. 15 schematically shows an enlarged view of the joint portion of a lead according to one embodiment of the present invention that is pressed into a battery housing.

[0071] FIG. 16 schematically shows an enlarged view of the joint portion of a lead according to one embodiment of the present invention that is pressed into a battery housing.

[0072] FIG. 17 schematically shows a lid with a stopper attached according to one embodiment of the present invention.

[0073] FIG. 18 schematically illustrates a battery pack according to one embodiment of the present invention.

[0074] FIG. 19 schematically illustrates an automobile according to one embodiment of the present invention.

[0075]

[0076] Terms and words used in this specification and claims shall not be interpreted as being limited to their ordinary or dictionary meanings, but shall be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0077] The terms used in this specification are used merely to describe exemplary embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise.

[0078] <Definition>

[0079] Throughout this specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0080] Throughout the entire specification, unless specifically stated otherwise, each component may be singular or plural.

[0081] Throughout the entire specification, the statement that any configuration is disposed on the "upper (or lower)" of a component or on the "upper (or lower)" of a component may mean not only that any configuration is disposed in contact with the upper (or lower) surface of said component, but also that another configuration may be interposed between said component and any configuration disposed on (or below) said component.

[0082] Throughout this specification, where it is stated that one component is "connected," "coupled," or "connected" to another component, it should be understood that said components may be directly connected or connected to each other, but that other components may be "interposed" between each component, or that each component may be "connected," "coupled," or "connected" through other components.

[0083] Throughout the entire specification, "A and / or B" means A, B, or A and B unless specifically stated otherwise, and "C to D" means C or more and D or less unless specifically stated otherwise.

[0084] Throughout the entire specification, the term "axial direction" refers to the axial direction in which the axis forming the winding center of the jelly-roll type electrode assembly extends, the term "radial direction" refers to the direction toward or toward the winding axis, and the term "circumferential direction" refers to the direction surrounding the axis.

[0085] The embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the present invention and do not represent all aspects of the technical concept of the present invention; therefore, it should be understood that various equivalents and modifications that can replace them may exist at the time of filing this application.

[0086]

[0087] <Battery housing and first electrode terminal>

[0088] Hereinafter, the structure of a battery cell according to an embodiment of the present invention will be described with reference to FIGS. 1 to 17.

[0089] The battery cell of the present invention may be, for example, a cylindrical battery cell in which the ratio of the form factor (defined as the ratio of the diameter of the cylindrical battery cell to the height, i.e., the ratio of the diameter (Φ) to the height (H)) is approximately greater than 0.4.

[0090] Here, the form factor refers to a value representing the diameter and height of a cylindrical battery cell. The cylindrical battery cell may be, for example, a 46110 cell, a 48750 cell, a 48110 cell, a 48800 cell, or a 46800 cell. In the numerical 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 indicates that the cross-section of the cell is circular.

[0091] The battery cell may be a cylindrical battery cell that is approximately cylindrical in shape, with a diameter of approximately 46 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0092] A battery cell according to another embodiment may be a cylindrical battery cell having a roughly cylindrical shape, with a diameter of approximately 48 mm, a height of approximately 75 mm, and a form factor ratio of 0.640.

[0093] A battery cell according to another embodiment may be a cylindrical battery cell having a diameter of approximately 48 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0094] A battery cell according to another embodiment may be a cylindrical battery cell having a diameter of approximately 48 mm, a height of approximately 80 mm, and a form factor ratio of 0.600.

[0095] A battery cell according to another embodiment may be a cylindrical battery cell having a diameter of approximately 46 mm, a height of approximately 80 mm, and a form factor ratio of 0.575.

[0096]

[0097] Referring to FIG. 1, the battery housing (10) of the present invention has a cylindrical side wall portion (11), a bottom portion (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).

[0098] The bottom portion (12) and the side wall portion (11) can be manufactured by forming a conductive metal sheet using a deep drawing process and trimming the front end of the side wall portion (11) with a punch while holding it with a blank holder.

[0099] Alternatively, the bottom portion (12) and the side wall portion (11) may be manufactured by forming a conductive metal sheet using a deep drawing process, supporting the leading edge of the side wall portion (11) through a jig, and then processing it with a cutting means so that it is perpendicular to the bottom portion (12).

[0100] In one embodiment of the present invention, the conductive metal sheet may include, for example, aluminum, steel, stainless steel, etc., but is not limited thereto.

[0101] In one embodiment of the present invention, when the battery housing (10) is manufactured by trimming, the battery housing (10) may comprise a first vertical portion forming a portion of the inner surface of the side wall portion, an inclined portion forming the remaining portion of the inner surface of the side wall portion and extending obliquely from the end of the first vertical portion outwardly in the axial direction such that the length of the radial circumference portion increases, a horizontal portion extending horizontally from the end of the inclined portion outwardly in the radial direction, and a second vertical portion connected to the end of the horizontal portion and forming the outer surface of the side wall portion.

[0102] In one embodiment of the present invention, when the inclined portion is included, when the lead (40) is press-fitted into the open end, the lead can be easily inserted into the axial inner side of the battery housing (10) by the inclined portion.

[0103] In one embodiment of the present invention, the height of the inclined portion may be in the range of 0.1 mm to 0.4 mm, or 0.15 mm to 0.3 mm.

[0104] In one embodiment of the present invention, the shape of the side wall portion (11) of the battery housing (10) may have a chamfered shape such as a beveled edge at the open end, a rounded shape, or an angled shape in which the horizontal and vertical portions of the side wall portion (11) are perpendicular to each other by processing with a cutting means.

[0105] Specifically, in one embodiment of the present invention, when the battery housing (10) is manufactured by trimming, the inclined portion of the battery housing (10) may have a chamfered shape such as a bevel or a rounded shape.

[0106] A hole is formed in the central part of the bottom portion (12), and a first electrode terminal (13) can be fitted into the hole. The first electrode terminal (13) can be fixed by riveting to the bottom portion (12) with a terminal gasket (14) interposed therebetween. The terminal gasket (14) is interposed between the first electrode terminal (13) and the bottom portion (12) to seal the inside and outside of the battery housing (10) to prevent leakage of the electrolyte and to electrically insulate the first electrode terminal (13) and the bottom portion (12).

[0107] However, the method of connecting the first electrode terminal (13) and the bottom part (12) is not limited to this. For instance, if there is a structure that can seal the space between the first electrode terminal (13) and the bottom part (12) and electrically insulate the first electrode terminal (13) and the bottom part (12), various other fixing methods, such as a bolt-nut connection method, a glass seal method, or a chrome coating & PP-MAH heat bonding method, can also be applied.

[0108] The first electrode terminal (13) may have a first polarity, and the battery housing (10) may have a second polarity. Accordingly, the bottom portion (12) of the battery housing (10) and the side wall portion (11) connected thereto may both have a second polarity.

[0109] Accordingly, the battery housing (10) may have both a first electrode terminal (13) and a second electrode terminal (15) disposed at one axial end. In this case, the busbar connected to the first electrode terminal (13) and the busbar connected to the second electrode terminal (15) may both be located at one axial end of the battery housing (10).

[0110] In one embodiment of the present invention, the first electrode terminal (13) may be a positive terminal and the second electrode terminal (15) may be a negative terminal. Of course, the opposite may also be true.

[0111]

[0112] Electrode Assembly

[0113] In one embodiment of the present invention, an electrode assembly (20) is accommodated in the battery housing (10). The electrode assembly (20) is prepared by preparing a first electrode (21), a second electrode (22), and a separator (28) that have a predetermined width and extend in the longitudinal direction as shown in FIG. 2, and then forming a laminate by stacking the first electrode (21), the separator (28), the second electrode (22), and the separator (28) in the order shown in FIG. 3, and then winding the laminate around a core axis to produce a jelly-roll shape.

[0114] In one embodiment of the present invention, the first electrode (21) may be an anode and the second electrode (22) may be a cathode. Of course, the opposite may also be true.

[0115] In one embodiment of the present invention, the first electrode (21) and the second electrode (22) are manufactured in the form of a sheet. The electrode sheet may be manufactured in a form in which an active material layer (24) is coated on the surface of a metal foil (23). The electrode sheet may have a retaining portion (25) region coated with the active material layer (24) and a non-retaining portion (26) region not coated with the active material layer (24). The positive electrode sheet may have a non-retaining portion (26) region on one side in the width direction, and the negative electrode sheet may have a non-retaining portion (26) region on the other side in the width direction.

[0116]

[0117] In one embodiment of the present invention, the anode can be manufactured by coating an anode forming composition comprising an anode active material, a binder, a conductive material, and a solvent, etc., onto an anode current collector.

[0118] In one embodiment of the present invention, the positive active material may be a conventional positive active material that can be used in the positive of a conventional electrochemical device. For example, the positive active material may be lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium iron oxide, or a lithium composite oxide that is a combination of these.

[0119] At this time, the positive active material may be included in an amount of 80 to 99 weight%, preferably 85 to 98 weight%, based on the total weight of the solid content of the composition for forming the positive electrode. When the content of the positive active material satisfies the above-described range, excellent capacity characteristics can be exhibited.

[0120] The above positive current collector is not particularly limited as long as it is conductive without causing chemical changes in the battery. For example, the above positive current collector may be made of stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel with a surface treated with carbon, nickel, titanium, silver, etc.

[0121] The above binder is a component that assists in the bonding of the active material and the conductive material, and in the bonding to the current collector, and can typically be added in an amount of 1% to 30% by weight based on the total solid weight of the anode-forming composition. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluororubber, and various copolymers.

[0122] The above conductive material can typically be added in an amount of 1% to 30% by weight based on the total solid content weight of the anode-forming composition.

[0123] Such conductive materials are not particularly limited as long as they are conductive without causing chemical changes in the battery, and for example, carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black; conductive fibers such as carbon fibers or metal fibers; metal powders such as carbon fluoride, aluminum, or nickel powder; conductive whiskies such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives may be used. Specific examples of commercially available conductive materials include acetylene black series products such as Chevron Chemical Company, Denka Black (Singapore Private Limited), and Gulf Oil Company, Ketjenblack, EC series (Armak Company products), Vulcan XC-72 (Cabot Company products), and Super P (Timcal products).

[0124] In addition, the above-mentioned positive active material layer may optionally include a dispersant as needed.

[0125] The above-mentioned dispersant may be used without special restrictions as long as it is used as a dispersant for the anode, and, for example, an aqueous dispersant or an organic dispersant may be selectively used as needed. Preferably, the dispersant is a cellulose-based compound, polyalkylene oxide, polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl acetal, polyvinyl ether, polyvinyl sulfonic acid, polyvinyl chloride (PVC), polyvinylidene fluoride, chitosans, starch, amylose, polyacrylamide, poly-N-isopropylacrylamide, poly-N,N-dimethylacrylamide, polyethyleneimine, polyoxyethylene, poly(2-methoxyethoxyethylene), poly(acrylamide-co-diallyldimethylammonium chloride), acrylonitrile / butadiene / styrene (ABS) polymer, a mixture of acrylonitrile / styrene / acrylate ester (ASA) polymer and propylene carbonate, styrene / acrylonitrile (SAN) copolymer, Examples include methyl methacrylate / acrylonitrile / butadiene / styrene (MABS) polymer, styrene butadiene rubber, nitrile butadiene rubber, fluororubber, etc., and any one or more of these may be used. Hydrogenated nitrile butadiene rubber (H-NBR) may be used. If the anode active material layer further includes a dispersant, the dispersibility of the components of the anode active material layer, particularly the conductive material, may be increased, but is not limited thereto.

[0126] In addition, the above solvent may be a solvent generally used in the relevant technical field, and may include dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water, and one of these alone or a mixture of two or more may be used. The amount of the above solvent used is sufficient if it has a viscosity that dissolves or disperses the anode active material, conductive material, and binder, taking into account the coating thickness of the slurry and the manufacturing yield, and subsequently provides excellent thickness uniformity when coated for anode manufacturing.

[0127] The cathode according to the present invention can be manufactured by coating a cathode-forming composition comprising the above-described cathode active material, binder, conductive material, and solvent, etc., onto a cathode current collector. Additionally, the cathode-forming composition may optionally further include a dispersant as needed.

[0128] As the above-mentioned negative electrode active material, a compound capable of reversible intercalation and deintercalation of lithium may be used. Preferably, the negative electrode is a silicon-based negative electrode active material, a carbon-based negative electrode active material, Li exhibiting high capacity characteristics. x Fe2O3(0≤x≤1), Li x WO2(0≤x≤1), Sn x Me 1-x Me y O z(Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, Group 1, 2, and 3 elements of the periodic table, halogens; 0 <x≤1; 1≤y≤3; 1≤z≤8) 등의 금속 복합 산화물; 리튬 금속; 리튬 합금; 주석계 합금; SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, 및 Bi2O5등의 금속 산화물; 폴리아세틸렌 등의 도전성 고분자; Li-Co-Ni 계 재료; 티타늄 산화물; 리튬 티타늄 산화물 등의 음극 활물질을 더 사용할 수 있다. 상기 규소계 음극 활물질은 Si, SiOx(0.1<x<5), Si-금속 합금, Mg와 같은 금속이 도핑 또는 화학 결합된 실리콘 산화물 입자(SiOx, 0.1<x<5) 및 Si와 SiOx(0.1<x<5)의 합금으로 이루어진 군에서 선택된 하나 이상을 포함할 수 있다. 상기 탄소계 음극 활물질은 천연 흑연, 인조 흑연, 비정질 하드카본(hard carbon), 저결정질 소프트카본(soft carbon), 카본 블랙, 아세틸렌 블랙, 케첸 블랙, 수퍼 P, 그래핀 (graphene), 및 섬유상 탄소로 이루어진 군으로부터 선택되는 하나 이상을 포함할 수 있다.

[0129] The above-mentioned negative current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., and aluminum-cadmium alloy may be used. In addition, the above-mentioned negative current collector may typically have a thickness of 3 μm to 500 μm, and, similar to the positive current collector, fine irregularities may be formed on the surface of the current collector to strengthen the bonding strength of the negative active material. For example, it may be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0130] The conductive material, binder, solvent, or dispersant included in the above-described cathode-forming composition may be applied without special limitations as long as it is conventionally usable in the electrode-forming composition, and for example, the conductive material, binder, solvent, or dispersant described in the above-described anode-forming composition may be applied.

[0131]

[0132] In one embodiment of the present invention, the unexposed portion (26) region may be exposed or protrude in the width direction from the laminate as shown in FIGS. 2 and 3. The unexposed portion (26) itself may function as an electrode tab.

[0133] In one embodiment of the present invention, notches may be formed at predetermined intervals in the blank portion (26) to form flag-shaped notching tabs (27).

[0134] In one embodiment of the present invention, the notching tabs (27) may be in the shape of an isosceles trapezoid as shown in FIGS. 2 and 3. However, their shape may be various shapes such as a semicircle, a semi-ellipse, a triangle, a rectangle, a parallelogram, etc.

[0135] In one embodiment of the present invention, the notching tabs (27) may have a uniform width arranged along the longitudinal direction. However, the width of the notching tabs may gradually or stepwise widen from the core side to the outer circumference side.

[0136] In one embodiment of the present invention, the height of the notching tab (27) may be gradually increased from the winding side toward the radial outer side. However, the height of these notching tabs (27) may be implemented in a constant or gradually decreasing form.

[0137] In one embodiment of the present invention, the structure may be such that a notching tab (27) is omitted in a predetermined section of the radially inner end and a predetermined section of the radially outer end of the bare portion (26). However, it is obvious that a notching tab may not be removed from the radially inner end of the bare portion, and a notching tab may not be removed from the radially outer end of the bare portion.

[0138]

[0139] In one embodiment of the present invention, the notching tab (27) of the jelly-roll type electrode assembly (20) may be flattened by being folded radially. The notching tab (27) may be folded radially inward or outward. For example, as shown in FIGS. 4 and 5, the notching tab (27) may be folded radially inward.

[0140] In one embodiment of the present invention, the notching tabs (27) may be folded one by one during the process of winding the laminate to form a jelly-roll type electrode assembly (20). Alternatively, the notching tabs (27) may be folded all at once after winding the laminate to form a jelly-roll type electrode assembly.

[0141] In one embodiment of the present invention, the notching tabs (27) of the first electrode (21) and the notching tabs (27) of the second electrode (22), which are thus radially bent and stacked, can each provide a plane substantially perpendicular to the axial direction at both axial ends of the electrode assembly (20) as shown in FIG. 5.

[0142] In one embodiment of the present invention, a collector plate (31) can be bonded to a substantially flat surface provided by bending a notching tab (27) exposed at both axial ends of the electrode assembly (20), as shown in FIG. 6.

[0143] In one embodiment of the present invention, the current collector plate (31) can be manufactured by punching, trimming, piercing, and folding a metal sheet.

[0144] In one embodiment of the present invention, referring to FIG. 6, the current collector plate (31) may have a terminal connection portion (32) extending radially from the center, a ring portion (33) connecting the centrifugal edge of the terminal connection portion (32) in a circumferential direction, and an electrode connection portion (34) extending from the ring portion (33) toward the center but not connected to the terminal connection portion (32). The center of the terminal connection portion (32) may cover at least a portion of the core hollow of the electrode assembly (20).

[0145] In one embodiment of the present invention, the electrode connecting portion (34) may be joined to the notching tab (27) of the first electrode (21) of the electrode assembly (20) by means such as laser welding before the electrode assembly (20) is placed in the battery housing (10).

[0146] In one embodiment of the present invention, referring to FIG. 7, a current collector plate may not be connected to the notching tab (27) of the second electrode (22) of the electrode assembly (20). Of course, the present invention is not limited to a structure in which a current collector plate is not connected to the notching tab (27) of the second electrode (22).

[0147] In one embodiment of the present invention, as shown in FIGS. 8 and 9, the electrode assembly (20) can be received in the battery housing (10) in a state where the current collector plate (31) is aligned toward the bottom portion (12) of the battery housing (10). At this time, an insulator (19) can be interposed between the current collector plate (31) and the bottom portion (12) of the battery housing (10) so that the current collector plate (31) and the bottom portion (12) are electrically insulated.

[0148] In one embodiment of the present invention, the terminal connection portion (32) of the current collector plate (31) can be joined to the first electrode terminal (13) fixed to the battery housing (10) by means such as resistance welding, ultrasonic welding, or laser welding. As shown in FIG. 9, a welding device for forming the welded portion between the current collector plate (31) and the first electrode terminal (13) can perform welding by approaching the back side of the center of the terminal connection portion (32) of the current collector plate (31) through the hollow portion of the core of the electrode assembly (20) from the axial other end of the electrode assembly (20). Of course, in addition to this, the current collector plate (31) and the first electrode terminal (13) can also be joined by brazing or soldering methods. That is, various methods can be applied to the current collector plate (31) and the first electrode terminal (13) as long as there is a joining method that can electrically connect and mutually fix them.

[0149] Referring to FIG. 10, with the electrode assembly (20) housed in the battery housing (10) and the first electrode (21) connected to the first electrode terminal (13), the notching tab (27) of the second electrode (22) can be directly connected to a lead (40) that is pressed in through the open end of the battery housing (10). Accordingly, the second electrode (22) is electrically connected through the welded portion of the notching tab (27) and the lead (40). Of course, other joining methods such as brazing or soldering can also be applied to the notching tab (27) and the lead (40) in addition to the welding method.

[0150] In one embodiment of the present invention, the edge of the lead (40) is joined to the side wall portion (11) of the battery housing (10) to be electrically connected and sealed. Accordingly, the second electrode (22) can be electrically connected to the lead (40) and the battery housing (10). Various methods capable of electrically connecting and sealing the joint portion (M) between the lead (40) and the battery housing (10), such as welding, brazing, and soldering, can also be applied. This will be described in detail later.

[0151]

[0152] <Lead>

[0153] Hereinafter, the structure of the lead of the present invention and a battery cell to which it is applied will be described with reference to FIGS. 11 to 17.

[0154] In one embodiment of the present invention, the lead (40) can be manufactured by forming a circular metal sheet with a press.

[0155] In one embodiment of the present invention, the lead (40) has a substantially disc shape so as to be able to block the open end of the battery housing (10).

[0156] In one embodiment of the present invention, the lead (40) may include, in order from the radially outer side to the inner side as shown in FIG. 13, a butt surface (48), a curved surface (47), a first inclined surface (46), a support surface (45), a second inclined surface (49), and an electrode connection part (41).

[0157] In one embodiment of the present invention, the lead (40) may have a cross-sectional shape in the A'A direction that is asymmetric with respect to the radial inner center, as shown in FIG. 11 to 13. That is, as shown in FIG. 13, the lead (40) may include a butt surface (48), a curved surface (47), a support surface (45), and a bridge (44) from the radially outer side to the inner side.

[0158] In one embodiment of the present invention, the abutting surface (48) is provided on the radial outer edge of the lead (40), and the outer surface of the abutting surface (48) extends to contact the inner surface of the side wall portion of the battery housing (10). Specifically, the abutting surface (48) is inclined with respect to the axial direction so as to increase the length of the radial circumference portion, and at least a portion of the abutting surface (48) and at least a portion of the inner surface of the side wall portion (11), that is, at least a portion of the protrusion (11a), are joined together.

[0159] In one embodiment of the present invention, the lead (40) covers the open end of the battery housing (10), and the lead (40) can be pressed in through the open end. Subsequently, at least a portion of the butt surface (48) and at least a portion of the protrusion (11a) can be joined to be electrically connected and sealed. The joining can be performed using various methods capable of electrically connecting and sealing, such as welding, specifically butt welding, brazing, and soldering, and preferably by laser welding.

[0160] In one embodiment of the present invention, the thickness of the abutting surface (48) is greater than the thickness of the side wall portion (11) of the battery housing (10) facing it, or the hardness of the abutting surface (48) of the lead (40) is superior to the hardness of the side wall portion (11) of the battery housing (10), so that the lead (40) is assembled with the battery housing (10) by a press fit, and the side wall portion (11) of the open end of the battery housing (10) has a protrusion (11a) that protrudes radially outward, and at least a part of the abutting surface (48) and at least a part of the inner circumference of the protrusion (11a) come into contact. At this time, the axial angle (θ) of the abutting surface (48) may be reduced compared to before the press fit, and thereby the contact area between the abutting surface (48) and the protrusion (11a) may be further increased.

[0161] In one embodiment of the present invention, the circularity (or roundness) of the lead (40) is superior to the circularity of the open end sidewall (11) of the battery housing (10), so that when the lead (40) is assembled with the battery housing (10) by an interference fit, the open end sidewall (11) of the battery housing (10) can be similar to the circularity of the lead (40).

[0162] In one embodiment of the present invention, there may be no gap between at least a portion of the abutting surface (48) and the inner surface of the protrusion (11a). In this case, the meaning of "substantially" may refer to the difference in error of the measuring instrument when measuring the gap between the lead (40) and the side wall (11). For example, the gap between at least a portion of the abutting surface (48) and the inner surface of the protrusion (11a) may be less than 10%, less than 9%, less than 8%, less than 7%, less than 6%, less than 5%, less than 4%, less than 3%, less than 2%, less than 1% of the thickness of the abutting surface (48), or may be in complete contact.

[0163] In one embodiment of the present invention, the gap between at least a portion of the abutting surface (48) and the inner surface of the protrusion (11a) may be 10 μm or less, 9 μm or less, 8 μm or less, 7 μm or less, 6 μm or less, 5 μm or less, 4 μm or less, 3 μm or less, 2 μm or less, 1 μm or less, or 0 μm (complete contact).

[0164] In one embodiment of the present invention, when the battery housing (10) is manufactured by trimming as described above, the battery housing (10) may comprise a first vertical portion forming a portion of the inner circumference of the side wall portion based on the case where the lead (40) is not pressed in, an inclined portion forming the remaining portion of the inner circumference of the side wall portion and extending obliquely from the end of the first vertical portion outward in the axial direction such that the length of the radial circumference portion increases, a horizontal portion extending horizontally from the end of the inclined portion outward in the radial direction, and a second vertical portion connected to the end of the horizontal portion and forming the outer surface of the side wall portion.

[0165] Meanwhile, in one embodiment of the present invention, when a lead (40) is pressed into a battery housing (10) that has been trimmed as shown in FIG. 16, the protrusion (11a) may further include an inclined portion (11b) at the end of the open end side in which the length of the radial circumference increases axially outward.

[0166] In this case, the abutting surface (48) is joined to the inner surface of the protrusion (11a) connected to the inclined portion (11b), so that there is substantially no gap between at least a part of the abutting surface (48) and the inner surface of the protrusion (11a), or the gap is 10 μm or less. That is, the inclined portion (11b) and the abutting surface (48) may not come into contact with each other. Meanwhile, due to the presence of the inclined portion (11b), as described above, the lead (40) can be easily inserted in the inner direction of the battery housing (10) when press-fitted into the battery housing (10).

[0167]

[0168] In one embodiment of the present invention, the abutting surface (48) may have an inclination of 1° to 30° or 5° to 25° with respect to the axial direction. For example, the abutting surface (48) may have a shape such as the side of a truncated cone rather than a cylindrical side shape. In this case, the angle of the abutting surface (48) with respect to the axial direction can be derived by measuring the angle (θ) formed between the cross-section of the abutting surface (48) and the winding axis, as shown in FIG. 13. Alternatively, the angle formed between the abutting surface (48) and the winding axis may be derived by measuring the angle formed between the plane contacting any point on the abutting surface (48) and the winding axis.

[0169] In one embodiment of the present invention, the thickness of the abutting surface (48) may be thicker than the thickness of the side wall portion (11). By making the thickness of the abutting surface (48) thicker than the thickness of the side wall portion (11), the side wall portion at the open end of the battery housing (10) may protrude radially outward more easily when the lead (40) is press-fitted into the battery housing (10).

[0170] In one embodiment of the present invention, the thickness of the abutting surface (48) may be in the range of 0.4 mm to 2 mm, 0.6 mm to 1.5 mm, or 0.8 mm to 1.2 mm.

[0171] In one embodiment of the present invention, the thickness of the side wall portion (11) may be in the range of 0.35 mm to 0.45 mm or 0.37 mm to 0.42 mm. However, the thickness of the abutting surface (48) may be greater than the thickness of the side wall portion (11).

[0172] In one embodiment of the present invention, the lead (40) is assembled with the battery housing (10) by an interference fit, so that the open end side wall (11) of the battery housing has a protrusion (11a) that protrudes radially outward as shown in FIG. 14.

[0173] Specifically, the protrusion (11a) may be formed by deforming the sidewall (11) on the open end side of the battery housing (10) as the lead (40) and the battery housing (10) are assembled by press fitting. Accordingly, the battery housing (10) may have a deformed cylindrical shape with a protrusion (11a) provided on the sidewall on the open end side.

[0174] In one embodiment of the present invention, the shape of the protrusion (11a) may vary depending on the shape of the butt surface (48) of the lead (40), but, for example, it may be part of an ellipsoid or part of a cone.

[0175] In one embodiment of the present invention, the pressure fit amount of the lead (40) may be within the range of 30 μm to 250 μm or 50 μm to 200 μm based on one side. In this case, the pressure fit amount may mean half the difference between the outer diameter of the lead (40) and the inner diameter (or inner diameter) of the battery housing (10) based on the time prior to the pressure fit. By satisfying the above-described range for the pressure fit amount of the lead (40), the degree of connection between the lead (40) and the battery housing (10) can be better, while mechanical damage to the battery cell can be reduced.

[0176] In one embodiment of the present invention, the curved surface (47) may have a downwardly convex cross-sectional shape that is connected to the lower end of the butting surface (48) of the lead (40), that is, the axial inner end of the butting surface (48), and extends radially inward as it extends axially inward.

[0177] In one embodiment of the present invention, the curved surface (47) may be extended to a point where the slope of the tangent line becomes 0 degrees. The point where the slope of the tangent line becomes 0 degrees on the curved surface (47) may be the part that extends to the innermost part in the axial direction on the curved surface (47). More preferably, the curved surface (47) may extend beyond 0 degrees and increase in the direction where the slope of the tangent line increases. At this time, the slope of the curved surface (47) may increase continuously, increase discontinuously, or remain constant.

[0178] Meanwhile, the curved surface (47) may be spaced apart from the electrode assembly (20). For example, a separation distance may be secured between the curved surface (47) and the electrode assembly (20). As the separation distance is secured, welding heat is not transferred to the electrode assembly during seam welding, and physical damage such as cracking or warping can be prevented in the electrode assembly, particularly in the unwelded area.

[0179] In one embodiment of the present invention, the curved surface (47) may have the shape of a U-shaped bend to improve weldability during seam welding. Due to the shape of the curved surface (47), the lead (40) may be suitable for press-fitting through the open end of the battery housing (10). Additionally, the insertion depth of the lead (40) may not be restricted due to interference between the curved surface (47) and the electrode assembly (20).

[0180]

[0181] In one embodiment of the present invention, the first inclined surface (46) may be provided between the curved surface (47) and the support surface (45). The first inclined surface (46) extends axially outward as it moves radially inward, and its slope may be substantially constant or change to a second slope. For example, the slope of the first inclined surface (46) may be approximately 10° to 50°, for example, around 50°.

[0182] In one embodiment of the present invention, the first inclined surface (46) and the curved surface (47) may provide a cross-sectional shape in which the lead (40) can be elastically deformed radially inward. Accordingly, when the lead (40) is pressed into an open end, the deformation of the lead (40) may change slightly. Meanwhile, in one embodiment of the present invention, since the thickness of the side wall portion (11) of the battery housing (10) is thinner than the abutting surface (48) of the lead (40), the side wall portion (11) on the open end side of the battery housing (10) changes to form a protrusion (11a). Even at this time, due to the first inclined surface (46) and the curved surface (47) of the lead (40), the U-shape is compressed and then spread out, causing the inclination (θ) of the abutting surface (48) to decrease slightly, and the side wall portion (11) protrudes radially outward, thereby securing a radial contact force between the side wall portion (11) of the battery housing and the abutting surface (48) of the lead. In this process, the abutting surfaces (48) can be strongly abutted without twisting. In this case, tack welding is not required, and the laser of the butt weld does not enter the internal space of the battery housing (10), so damage to the electrode assembly (20) is not caused. Also, there is no concern that the weld thickness will become thin, so it has sufficient welding strength.

[0183] In one embodiment of the present invention, the butt joint surface (48) can be secured to be longer than, for example, 0.7 mm.

[0184] In one embodiment of the present invention, a support surface (45) extending horizontally in the radial direction is provided radially inward from the curved surface (47) in the lead (40). The support surface (45) is connected to the radially inward end of the first inclined surface (46) and can extend horizontally radially inward from the connection point.

[0185] In one embodiment of the present invention, the surface of the support surface (45) has a flat planar shape, so when the battery cell is set up so that the lead (40) is placed on the floor as shown in FIG. 2, it can serve as the foot of the battery cell.

[0186] In one embodiment of the present invention, with reference to FIG. 14 and the like, the axial outer surface of the support surface (45) may be positioned further outward in the axial direction than the axial outer end of the butt surface (48). Thus, even if the battery cell is placed upright as shown in FIG. 2 so that the lead (40) touches the floor and the battery cell is placed thereon, the welded portion between the lead (40) and the battery housing (10) can be prevented from directly touching the floor, thereby protecting the welded portion.

[0187] In one embodiment of the present invention, an electrode connection portion (41) extending horizontally in the radial direction is provided on the lead (40) radially inward from the support surface (45). Referring to FIG. 14, the axial inner surface, i.e., the bottom surface, of the electrode connection portion (41) may be positioned further inward in the axial direction than the point where the slope is zero among the axial inner ends of the curved surface (47). That is, the electrode connection portion (41) is provided at a position that is axially recessed radially inward from the support surface (45), and the axial inner surface of the electrode connection portion (41) may be positioned further inward in the axial direction than the axial inner end of the curved surface (47).

[0188] In one embodiment of the present invention, the insertion depth of the lead (40) into the battery housing (10) may be determined by the electrode connection portion (41) of the lead (40) and the tab connection portion of the second electrode (22) of the electrode assembly (20) accommodated in the battery housing (10). That is, the bottom surface of the electrode connection portion (41) may be provided closest to the electrode assembly (20) than the remaining bottom surface of the lead (40). In this case, when the electrode connection portion (41) is coupled with the electrode assembly (20), the remaining portion of the lead (40), excluding the electrode connection portion (41), may be spaced apart from the electrode assembly (20).

[0189] In one embodiment of the present invention, the electrode connecting portion (41) may be in close contact with the tab of the second electrode (22) of the electrode assembly (20), and they may be joined together. The joining may be achieved by welding. The weld (W) between the electrode connecting portion (41) and the notching tab (27) of the second electrode (22) may be formed by a laser irradiated from the axial outer surface of the electrode connecting portion (41) from the axial outer side, as shown in FIG. 17. The laser may be irradiated in a scanning manner along the radial direction to form a weld (W) that extends radially. The electrode connecting portion (41) may be joined face-to-face with the electrode assembly (20). The electrode connecting portion (41) may be joined with the metal foil (23).

[0190] As such, the lead (40) functions as a cover that closes the open end of the battery housing (10), while also functioning as a collector plate for the second electrode (22). Accordingly, the lead (40) can have a second polarity, and the side wall (11) welded thereto and the bottom part (12) connected thereto can also have a second polarity.

[0191] In one embodiment of the present invention, the electrode connection portion (41) may be extended radially outward by more than half the radius of the battery housing (10). Preferably, the electrode connection portion (41) may be extended by more than 0.7 times the radius of the battery housing (10). The electrode connection portion (41) may be extended flatly in the radial direction.

[0192] In one embodiment of the present invention, the electrode connection portion (41) may occupy 50% or more of the total area of ​​the battery housing (10).

[0193] In one embodiment of the present invention, the electrode connection portion (41) of the lead (40) may have a flat, extended bottom surface shape with sufficient width, thereby sufficiently securing a welding area with the tab of the second electrode (22). At this time, the height of the bottom surface of the electrode connection portion (41) may be lower than the height of the lower end of the curved surface (47). That is, the electrode connection portion (41) may protrude further inward in the axial direction than the curved surface (47). Then, the lower end of the curved surface (47) may be spaced apart in the axial direction from the electrode assembly (20) housed inside the battery housing (10), while the bottom surface of the electrode connection portion (41) may be in close contact with the electrode assembly (20).

[0194] In one embodiment of the present invention, a current collector plate (31) may be joined to the tab of the second electrode (22) and electrically connected, and the electrode connection part (41) may be joined to the current collector plate (31) and electrically connected to the tab of the second electrode (22). That is, the current collector plate (31) may be welded to the tab of the second electrode (22), and the electrode connection part (41) of the lead (40) may be welded to the current collector plate (31).

[0195] In another embodiment of the present invention, the electrode connection portion (41) may be electrically connected by being directly bonded to the tab of the second electrode (22).

[0196] Specifically, the structure may have a tap of the second electrode (22) welded to the electrode connection portion (41) of the lead (40) to be electrically connected without a separate current collector plate (31). That is, since the lead (40) is coupled to the battery housing (10) to cover the open end of the battery housing (10) and simultaneously electrically connected to the electrode assembly (20), a current collector plate (31), for example, a negative current collector plate (31), may not be separately provided. In other words, the lead (40) of the present invention may be provided as a so-called integrated lead that can perform the function of a current collector plate. Accordingly, the joint portion between the lead (40) and the battery housing (10) is simplified, and since there is no need to use a current collector plate (31) when electrically connecting the electrode assembly (20) to the lead (40), the number of parts and assembly steps are reduced, and the internal volume is further secured to increase energy density.

[0197] In one embodiment of the present invention, the joint portion of the electrode connection part (41) and the tab of the second electrode (22) may be extended in a radial direction. That is, the electrode connection part (41) may be extended toward the flat part (43) and the support surface (45). Specifically, the electrode connection part (41) may be extended in a centripetal direction toward the flat part (43), and the electrode connection part (41) may be extended radially toward the support surface (45). In this case, since the length of the welding length (LFW, Lid Foil tab Welding) between the electrode connection part (41) and the metal foil (23) can be secured long, the internal resistance of the battery cell can be reduced.

[0198] In one embodiment of the present invention, the electrode connecting portion (41) is a plurality of and may be arranged radially with respect to the center of the lead (40) and arranged at equal intervals in the circumferential direction.

[0199] In one embodiment of the present invention, the electrode connection portion (41) may be provided in three portions spaced 120° apart.

[0200] In one embodiment of the present invention, the electrode connection portion (41) may be provided in three parts. When the electrode connection portion (41) is provided in three parts, the multiple electrode connection portions (41) can form a single plane, thereby making it easier to secure stable flatness with the electrode assembly (20). Additionally, the lead (40) locally contacts only the welding position of the notching tab (27) of the second electrode to secure adhesion, and the resistance to bulging of the lead (40) due to the internal pressure of the battery cell can be secured.

[0201] In one embodiment of the present invention, the lead (40) may further include at least one bridge (44). The bridge (44) may be provided in multiple numbers, for example, three. The bridge (44) may extend radially from the flat portion (43). The bridge (44) may be formed to partition two adjacent electrode connection portions (41). The bridge (44) may extend from the flat portion (43) toward the abutting surface (48).

[0202] In one embodiment of the present invention, a plurality of electrode connection parts (41) can be more clearly partitioned and spaced apart by the bridge (44). In this way, the bridge (44) can reinforce the rigidity of the lead (40).

[0203] In one embodiment of the present invention, the upper surface of the bridge (44) may be formed axially outward from the upper surface of the electrode connection part (41) but axially inward from the upper surface of the flat part (43). When the bridge (44) is formed in this way, the rigidity of the lead (40) can be reinforced more strongly.

[0204] In one embodiment of the present invention, the protrusion height of the bridge (44) may correspond to or be lower than the protrusion height of the support surface (45).

[0205] In one embodiment of the present invention, the protrusion height of the bridge (44) corresponds to the protrusion height of the support surface (45), so that they can form a single plane. In this case, when the battery housing (10) is set up so that the lead (40) of the battery housing (10) faces the floor, the bridge (44) can also come into contact with the floor together with the support surface (45).

[0206] In one embodiment of the present invention, if the height of the bridge (44) is lower than that of the support surface (45), the support surface (45) may provide an annular support surface.

[0207] In one embodiment of the present invention, between the support surface (45) and the electrode connection part (41), a second inclined surface (49) may be provided, which extends axially inward as it moves radially inward, and whose slope is substantially constant or changes to a third slope. For example, the absolute value of the third slope may be approximately 75 degrees. The absolute value of the second slope of the first inclined surface (46) may be smaller than the absolute value of the third slope of the second inclined surface (49). That is, the second inclined surface (49) may be steeper than the first inclined surface (46). Accordingly, the radial length of the support surface (45) and the electrode connection part (41) can be maximized.

[0208]

[0209] <Injection point>

[0210] In one embodiment of the present invention, the lead (40) of the present invention may further include an injection port (42) in the central part of the lead (40). When the lead (40) covers the open end of the battery housing (10), the injection port (42) may be aligned with the core hollow of the electrode assembly (20) housed in the battery housing (10).

[0211] In one embodiment of the present invention, the injection port (42) may be provided on a flat portion (43) that protrudes axially outward from the bottom surface of the lead (40), i.e., the electrode connection portion (41) of the lead (40), as shown in FIG. 13, etc. The height of the flat portion (43) may be lower than the height of the support surface (45). The flat portion (43) may be connected to the central edge of the electrode connection portion (41) and has a shape that extends axially outward as it moves inward in the radial direction.

[0212] In one embodiment of the present invention, the injection port (42) may be closed by covering it with a stopper (50) as shown in FIG. 17, etc. The rim portion of the stopper (50) may be sealed with the rim portion of the injection port (42). The sealing may be achieved by seam welding or by applying various other known sealing methods.

[0213] In one embodiment of the present invention, the plug (5) may be in the form of a plug and may be provided by deep drawing a thin metal sheet of 0.3 mm.

[0214] In one embodiment of the present invention, the height of the stopper (50) may also be lower than the height of the support surface (45) when the stopper (50) is covered and closed over the injection port (42). Since the stopper (50) is also positioned lower than the support surface (45), the stopper (50) may not receive a direct load even when the battery cell is set up so that the lid (40) touches the ground.

[0215] In one embodiment of the present invention, the flat portion (43) protrudes axially outwardly higher than the bottom of the lead, i.e., the electrode connection portion (41). Accordingly, the rim portion of the injection port (42) is spaced apart from the notching tab (27) of the second electrode (22). Therefore, after injecting the electrolyte through the injection port (42), when the plug (50) is placed over the injection port (42) and joined by means such as welding, the impact that the finishing joining process of the plug (50) may have on the battery performance, such as damage to the separator, can be minimized by transferring the joining heat toward the electrode assembly (20).

[0216] Meanwhile, in another embodiment of the present invention, the lead (40) may not include a separate injection port. In this case, when manufacturing a battery cell, if there is no separate injection port such as the bottom portion (12) of the battery housing (10), the process of injecting the electrolyte may be performed first before covering the battery housing (10) with the lead (40).

[0217] However, if the lead (40) further includes an injection port (42), the electrolyte can be injected through the injection port (42) even after the lead (40) is pressed into the battery housing (10) and the welded portion (W) and the joint portion (M) are formed. Then, compared to joining the lead (40) to the battery housing (10) in a state where the electrolyte has been injected, the heat from the joining can be prevented from affecting the electrolyte at all. In addition, when joining the plug (50) and the injection port (42), the flat portion (43) protrudes upward, so the possibility of the heat from the joining of the plug (50) affecting the electrolyte can also be reduced.

[0218] In one embodiment of the present invention, meanwhile, the injection port (42) formed in the center of the lead (40) may serve as a passage through which equipment configuration for welding the first electrode terminal (13) and the current collector plate (31) of the first electrode (21) can pass.

[0219] Accordingly, even after the lead (40) is joined to the battery housing (10), it is possible to join the first electrode (21) and the first electrode terminal (13) by introducing the welding equipment into the battery housing (10) through the injection port (42).

[0220] In one embodiment of the present invention, the flat portion (43) may further include a seating portion (43a) that is recessed inward in the axial direction and extends flatly in the radial direction. In one embodiment of the present invention, due to the seating portion (43a), interference with the electrolyte can be minimized when welding a plug (5) to the injection port (42).

[0221] In one embodiment of the present invention, the longer the length of the formed seating portion (43a) from the injection port (42) to the flat portion (43), the better the weldability with the plug (50) can be.

[0222]

[0223] Ventbu

[0224] In one embodiment of the present invention, the vent portion (60) may be formed on the upper surface of the lead (40). When a thermal event occurs in the battery cell, the vent portion (60) may be broken by the internal pressure of the high-temperature venting gas, and accordingly, the venting gas may be discharged from the battery cell to the outside.

[0225] In one embodiment of the present invention, the lead (40) is provided with a support surface (45) that extends radially and flatly from the butt surface (48) in the radially inner direction, the electrode connection portion (41) is provided at a position that is axially recessed from the support surface (45) in the radially inner direction, and the vent portion (60) may be provided on the support surface.

[0226] In one embodiment of the present invention, the vent portion (60) may be provided along the circumferential direction radially outward from the electrode connection portion (41). The vent portion (60) may be implemented as a soft portion or a thin portion in which both surfaces of the support surface (45) are notched.

[0227] In one embodiment of the present invention, the strength of the vent portion (60) is such that it does not deform under the force applied when the lead (40) is pressed into the battery housing (10), and it breaks when the internal pressure increases rapidly due to a short circuit or the like inside the battery housing (10), thereby separating the electrode connection portion (41) of the lead (40) and the abutting surface (48) of the lead (40). Accordingly, the electrical connection between the electrode connection portion (41) connected to the tab of the second electrode (22) and the battery housing (10) is severed, and the internal space of the battery housing (10) is opened to the outside, allowing the gas that caused the internal pressure to be discharged.

[0228] In one embodiment of the present invention, the vent portion (60) may be provided near the center of the support surface (45) in the radial direction, so as to be spaced apart from the first inclined surface (46) and the second inclined surface (49) in the radial direction. In this case, even if the support surface (45) is pressed, the pressing force is transmitted to the first inclined surface (46) and the second inclined surface (49) and does not affect the vent portion (60). Therefore, the force applied when joining the lead (40) to the battery housing (10) and the electrode assembly (20) may not deform the vent portion (60).

[0229] In one embodiment of the present invention, the vent portion (60) may be provided radially outward from the bridge (44). And these bridges (44) may be provided circumferentially between the electrode connection portions (41).

[0230] In one embodiment of the present invention, when the internal pressure of the battery housing (10) increases, this pressure is smoothly transmitted to the lower space of the bridge (44) positioned between the electrode connection parts (41) in the circumferential direction and acts as a force to lift the bridge (44) upward. In addition, the action of this force occurs intensively at three locations along the circumferential direction. Therefore, the internal pressure of the battery housing (10) is smoothly transmitted to the vent part (60), thereby inducing smooth rupture of the vent part (60).

[0231] In one embodiment of the present invention, the rupture pressure of the battery housing (10) can be controlled by controlling the vent portion (60) and the width, etc. For example, the vent portion (60) is such that the pressure inside the battery housing (10) is 15 to 35 kgf / cm² 2 It can be set to rupture when within the range. The vent portion (60) can be formed by notching to partially reduce the thickness of the lead (40). The vent portion (60) may have a thickness gradient. A thickness gradient means that when checking the cross-section of the vent portion (60), it is formed at a certain angle relative to a predetermined horizontal plane. This vent portion (60) ruptures when the pressure inside the battery housing (10) rises abnormally, thereby releasing all the internal gas to the outside.

[0232] In one embodiment of the present invention, the vent portion (60) may be provided in the form of a thin-walled portion on the support surface (45). However, the vent portion (60) formed by the lid (40) is not limited thereto. For example, the vent portion may be provided in a stopper (50) covering the liquid injection port (42), may be formed by the joint portion between the liquid injection port (42) and the stopper (50), or may be formed by the joint portion (M) between the lid (40) and the battery housing (10).

[0233]

[0234] Battery Packs and Cars

[0235] Referring to FIG. 18, the battery cell (72) with the lead applied as described above can be accommodated in the housing (71) of the battery pack (70). The battery pack (70) may be constructed using a battery module, which is an intermediate form of assembly, or the battery pack (70) may be constructed directly without a battery module as illustrated.

[0236] Since the aforementioned battery cell (72) itself has a large volume, there is no particular difficulty in implementing the battery pack (70) even without using an intermediate structure called a battery module. Furthermore, since the second electrode of the battery cell (72) is connected through a lead, the internal resistance is low and the energy density can be higher. Additionally, since the vent portion (60) structure is provided on the lead (40) so as not to occupy a separate space, the energy density can be further secured. Accordingly, the energy density of the battery pack (70) equipped with the battery cell (72) can be implemented at a higher level.

[0237] A battery pack (70) with such increased energy density can store the same amount of energy while reducing its volume and load. Therefore, if a battery pack (70) with such battery cells (72) is installed in a vehicle such as an electric vehicle (80) that uses electricity as an energy source, as shown in FIG. 19, the vehicle's mileage relative to energy can be further increased.

[0238] The embodiments described above should be understood as exemplary in all respects and not limiting, and the scope of the invention will be defined by the claims set forth below rather than by the detailed description above. Furthermore, the meaning and scope of the claims set forth below, as well as all modifications and variations derived from equivalents thereof, should be interpreted as being included within the scope of the invention.

[0239] Although the present invention has been described above with reference to the illustrated drawings, the present invention is not limited by the embodiments and drawings disclosed in this specification, and it is obvious that various modifications can be made by a person skilled in the art within the scope of the technical concept of the present invention. Furthermore, even if the effects of the configuration according to the present invention were not explicitly described while describing the embodiments of the present invention above, it is natural to acknowledge that the effects predictable by said configuration should also be recognized.

Claims

1. A battery housing having a side wall portion, a bottom portion connected to one axial end of the side wall portion, and an open end provided at the other axial end of the side wall portion; An electrode assembly in which a first electrode and a second electrode and a separator interposed between them are wound around a winding axis, and the tab of the second electrode is received inside a battery housing such that it faces the open end; and A lead covering the open end of the battery housing and electrically connected to the second electrode; comprising The above lead has a butt surface that contacts the inner surface of the side wall portion and an electrode connection portion that is electrically connected to the tab of the second electrode, and The above-mentioned butt surface is inclined with respect to the axial direction so that the length of the radial perimeter increases, and The above lead is assembled with the battery housing by an interference fit, and a portion of the side wall on the open end side of the battery housing is provided with a protrusion that protrudes radially outward. A battery cell characterized in that at least a portion of the abutting surface and at least a portion of the inner circumferential surface of the protrusion are joined.

2. In Claim 1 A battery cell characterized by having substantially no gap between at least a portion of the abutting surface and the inner circumferential surface of the protrusion.

3. In Claim 1, A battery cell characterized by a gap of 10 μm or less between at least a portion of the abutting surface and the inner circumferential surface of the protrusion.

4. In Claim 1, A battery cell characterized by the above-mentioned protrusion further including an inclined portion at the end of the open end side in which the length of the radial circumference increases axially outward.

5. In Claim 1, A battery cell characterized in that the above-mentioned abutting surface has an inclination of 1° to 30° with respect to the axial direction.

6. In Claim 1, A battery cell characterized in that the thickness of the abutting surface is thicker than the thickness of the side wall.

7. In Claim 1, A battery cell characterized in that the above-mentioned protrusion is formed by deforming the sidewall portion of the open end of the battery housing as the above-mentioned lead and the above-mentioned battery housing are assembled by press fitting together.

8. In Claim 1, A battery cell characterized by the interference fit amount of the above lead being within the range of 30 μm to 250 μm based on one side.

9. In Claim 1, A battery cell characterized in that the insertion depth of the lead into the battery housing is defined by the electrode connection portion of the lead and the tab connection portion of the second electrode of the electrode assembly accommodated in the battery housing.

10. In Claim 1, In the above lead, the radially inner side compared to the abutting surface is provided with a support surface that extends flatly in the radial direction, and A battery cell characterized in that the support surface is connected to the abutting surface through a curved surface provided at the axial inner end of the abutting surface.

11. In Claim 10, The electrode connection portion is provided at a position that is axially recessed radially inward from the support surface, and A battery cell characterized in that the axial inner surface of the electrode connection portion is positioned further inward in the axial direction than the axial inner end of the curved surface.

12. In Claim 11, A current collector plate is bonded to the tab of the second electrode and electrically connected, and A battery cell characterized in that the electrode connection portion is bonded to the current collector plate and electrically connected to the tab of the second electrode.

13. In Claim 11, A battery cell characterized in that the electrode connection portion is directly bonded to the tab of the second electrode and electrically connected.

14. In Claim 13, A battery cell characterized in that the joint portion of the electrode connection portion and the tab of the second electrode are extended in the radial direction.

15. In Claim 13, A battery cell characterized in that the electrode connection portion and the tab of the second electrode are joined by a weld formed by a laser irradiated on the surface of the electrode connection portion along the radial direction.

16. In Claim 1, A battery cell characterized by having a liquid injection port provided in the central part of the electrode connection portion.

17. In Claim 16, A battery cell characterized in that the above-mentioned injection port is provided on a flat portion that protrudes further axially outward than the electrode connection portion around the circumference of the above-mentioned injection port.

18. In Claim 16, A battery cell characterized by the above-mentioned protrusion being recessed inward in the axial direction and further including a seating portion that extends flatly in the radial direction.

19. In Claim 1, In the above lead, the radially inner side compared to the abutting surface is provided with a support surface that extends flatly in the radial direction, and The above electrode connection portions are provided in multiple numbers radially inward from the support surface, and A battery cell characterized in that the plurality of electrode connection portions are each recessed into the inner side of the battery housing and extended in the radial direction.

20. In Claim 19, A battery cell characterized in that the plurality of electrode connections are arranged radially with respect to the center of the lead.

21. In Claim 19, A battery cell characterized by the electrode connection portions being arranged at equal intervals in the circumferential direction.

22. In Claim 19, A battery cell characterized by having three electrode connections spaced at 120° intervals.

23. In Claim 1, The above lead includes a vent portion, and A battery cell characterized in that the above-mentioned vent portion is provided radially outward from the above-mentioned electrode connection portion.

24. In Claim 23, In the above lead, the radially inner side compared to the abutting surface is provided with a support surface that extends flatly in the radial direction, and The electrode connection portion is provided at a position that is axially recessed radially inward from the support surface, and A battery cell characterized in that the above-mentioned vent portion is provided on a support surface.

25. In Claim 1, The bottom portion of the battery housing is provided with a first electrode terminal that is electrically insulated from and fixed to the bottom portion, and A battery cell characterized in that the first electrode of the above electrode assembly is electrically connected to the first electrode terminal.

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

27. An automobile comprising the battery pack of claim 26.

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