Battery cell, battery pack comprising the battery cell, and vehicle

Abstract

A battery cell includes a battery case 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 open end portion provided at the other end portion of the side wall portion in the axial direction; an electrode assembly in which a first electrode and a second electrode and a separator provided between the first electrode and the second electrode are wound around a winding axis, and the electrode assembly is accommodated in the battery case so that a tab of the second electrode faces the open end portion; and a cover covering the open end portion and electrically connected to the second electrode, wherein the cover is provided with an abutment surface in contact with an 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 a length of a peripheral portion in a radial direction increases, the cover is electrically assembled with the battery case, and has a protrusion in which a portion of the side wall portion on the open end side protrudes outward in the radial direction, and at least a portion of the abutment surface and at least a portion of an inner surface of the protrusion engage with each other.

Description

Technical Field

[0001] This disclosure relates to battery cells, battery packs including the battery cells, and vehicles.

[0002] This application is based on and claims priority to Korean Patent Application No. 10-2024-0195743, filed with the Korean Intellectual Property Office on December 24, 2024, the disclosure of which is incorporated herein by reference in its entirety. Background Technology

[0003] Secondary batteries, which have high applicability to product groups and electrical characteristics such as high energy density, are typically used not only in portable devices, but also in electric vehicles (EVs) or hybrid electric vehicles (HEVs) powered by electric power sources.

[0004] These secondary batteries are attracting attention as a new energy source for improving eco-friendliness and energy efficiency because they not only have the major advantage of significantly reducing the use of fossil fuels, but also do not produce byproducts from energy use.

[0005] Currently widely used rechargeable batteries include lithium-ion batteries, lithium polymer batteries, nickel-cadmium batteries, nickel-metal hydride batteries, and nickel-zinc batteries. The operating voltage of these rechargeable battery cells is approximately 2.5 V to 4.5 V.

[0006] Therefore, when a higher output voltage is required, multiple battery cells are connected in series to form a battery module or battery pack. Alternatively, depending on the required charge / discharge capacity, multiple battery cells can be connected in parallel to form a battery module or battery pack. Thus, the number of battery cells included in a battery module or battery pack and their electrical connections can vary depending on at least one of the required output voltage and the required charge / discharge capacity.

[0007] Cylindrical, prismatic, and pouch-type battery cells are known as battery cell types. In the case of cylindrical battery cells, a separator, which serves as an insulator, is inserted between the positive and negative electrode plates and wound to form a wound electrode assembly, which is then inserted into the battery casing along with the electrolyte to form a battery.

[0008] In one embodiment, the battery casing of the cylindrical battery cell may have an open shape on one side, and the cover can be welded to one side of the battery casing. However, if the contact area between the battery casing and the cover is insufficient, there is a problem of deteriorated weldability between the battery casing and the cover, resulting in reduced weld strength, or product defects such as increased electrolyte leakage.

[0009] Recently, seam welding has been studied as an alternative to beading and crimping methods for joining the cover and battery casing. Seam welding is a process of welding the battery casing and cover together by joining the inner circumferential surface of the battery casing's sidewall and the outer circumferential surface of the cover. Furthermore, to increase the strength of the seam weld, the contact area at the joint between the battery casing and the cover should be wide to minimize the gap between them. Summary of the Invention

[0010] Technical issues

[0011] This disclosure aims to solve the above-mentioned problems, and therefore aims to provide a welding structure for a battery housing and a cover that maximizes the contact area between the battery housing and the cover, as well as a battery cell using the welding structure.

[0012] Specifically, this disclosure aims to provide a battery cell in which, although the sidewall portion of the battery housing is deformed during the process of pressing the cover into the battery housing, the mating surface of the cover is formed by the expected degree of deformation of the sidewall portion, thereby having a wide contact area between the mating surface of the cover and the battery housing.

[0013] In addition, this disclosure aims to provide a new interference fit shape between a battery casing and a cover that can increase the contact area between the battery casing and the cover and enhance the welding strength, as well as a battery cell using the new interference fit shape.

[0014] In addition, this disclosure aims to provide a battery cell that ensures the reliability of the electrical connection between the electrode assembly and the battery housing when the electrode assembly is connected to the battery housing and the electrode terminals, while omitting the current collector.

[0015] In addition, this disclosure aims to provide a battery cell that is economical in terms of manufacturing process and manufacturing cost by omitting the current collector.

[0016] However, the technical problems to be solved by this disclosure are not limited to those described above, and other problems not mentioned herein will be clearly understood by those skilled in the art based on the following description of this disclosure.

[0017] Technical solution

[0018] To achieve these objectives, according to one aspect of this disclosure, a battery cell, a battery pack including the battery cell, and a vehicle are provided according to the following embodiments.

[0019] According to a first embodiment, a battery cell is provided, comprising: a battery housing including a sidewall portion, a bottom connected to one axial end of the sidewall portion, and an open end portion disposed at another axial end of the sidewall portion; an electrode assembly in which a first electrode, a second electrode, and a diaphragm inserted between the first electrode and the second electrode are wound around a winding axis, and the electrode assembly is housed inside the battery housing such that the tab of the second electrode faces the open end portion; and a cover covering the open end portion of the battery housing and electrically connected to the second electrode, wherein the cover has a mating surface contacting the inner peripheral surface of the sidewall portion and an electrode connection portion electrically connected to the tab of the second electrode, wherein the mating surface is inclined relative to the axial direction such that the length of the radial peripheral portion is increased, wherein the cover is assembled to the battery housing by an interference fit, and thus a protrusion is provided, in which a portion of the sidewall portion of the battery housing on the open end side protrudes radially outward, and wherein at least a portion of the mating surface and at least a portion of the inner peripheral surface of the protrusion are engaged.

[0020] According to the second embodiment, in the first embodiment, there may be substantially no gap between at least a portion of the mating surface and the inner peripheral surface of the protrusion.

[0021] According to the third embodiment, in either the first or the second embodiment, the gap between at least a portion of the mating surface and the inner peripheral surface of the protrusion can be 10 μm or less.

[0022] 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 opening end side, in which the length of the radial peripheral portion increases outward along the axial direction.

[0023] According to the fifth embodiment, in any one of the first to fourth embodiments, the mating surface may have an inclined surface with a slope of 1° to 30° relative to the axial direction.

[0024] According to the sixth embodiment, in any one of the first to fifth embodiments, the thickness of the mating surface can be greater than the thickness of the sidewall portion.

[0025] According to the seventh embodiment, in any of the first to fifth embodiments, the protrusion can be formed by deformation of the sidewall portion of the battery housing on the opening end side when the cover and the battery housing are interference-fitted into each other.

[0026] According to the eighth embodiment, in any one of the first to seventh embodiments, the interference fit of the cap can be in the range of 30 μm to 250 μm on one side.

[0027] According to the ninth embodiment, in any one of the first to eighth embodiments, the pressing depth of the cover into the battery housing can be determined by the connection portion between the electrode connection portion of the cover and the tab of the second electrode of the electrode assembly housed in the battery housing.

[0028] According to the tenth embodiment, in any of the first to ninth embodiments, the cover may have a support surface that extends radially flat and is radially more inward than the mating surface, and the support surface may be connected to the mating surface via a curved surface provided at the axial inner end of the mating surface.

[0029] According to the eleventh embodiment, in the tenth embodiment, the electrode connection portion may be provided at a position that is recessed in the axial direction and is radially more inward than the support surface, and the axial inner surface of the electrode connection portion may be provided axially more inward than the axial inner end of the curved surface.

[0030] According to the twelfth embodiment, in the eleventh embodiment, the current collector can be joined to the tab of the second electrode for electrical connection, and the electrode connection portion can be joined to the current collector for electrical connection to the tab of the second electrode.

[0031] According to the thirteenth embodiment, in either the eleventh or twelfth embodiment, the electrode connection portion can be directly coupled to the tab of the second electrode for electrical connection.

[0032] According to the fourteenth embodiment, in the thirteenth embodiment, the junction between the electrode connection portion and the tab of the second electrode can extend radially.

[0033] According to the fifteenth embodiment, in either the thirteenth or fourteenth embodiment, the electrode connection portion and the tab of the second electrode can be joined by a welding portion formed by a laser irradiating the surface of the electrode connection portion in a radial direction.

[0034] According to the sixteenth embodiment, in any one of the first to fifteenth embodiments, a liquid injection port may be provided at the central portion of the electrode connection portion.

[0035] According to the seventeenth embodiment, in the sixteenth embodiment, the liquid injection port may be provided on a flat portion that protrudes further outward in the axial direction than the electrode connection portion, and the flat portion is formed around the liquid injection port.

[0036] According to the eighteenth embodiment, in any one of the first to sixteenth embodiments, the protrusion may further include a placement portion that is recessed inward in the axial direction and extends flat in the radial direction.

[0037] According to the nineteenth embodiment, in any one of the first to eighteenth embodiments, the cover may have a support surface that extends radially flat and is radially more inward than the mating surface, and the electrode connection portion may be provided as a plurality of electrode connection portions that are radially more inward than the support surface, and each of the plurality of electrode connection portions may be recessed into the battery housing and extend radially.

[0038] According to the twentieth embodiment, in the nineteenth embodiment, a plurality of electrode connection portions may be arranged radially around the center of the cover.

[0039] According to the twenty-first embodiment, in either the nineteenth or twentyth embodiment, the electrode connection portions may be arranged at equal intervals along the circumferential direction.

[0040] According to the twenty-second embodiment, in any one of the nineteenth to twenty-first embodiments, three electrode connection portions may be provided at 120° intervals.

[0041] According to the twenty-third embodiment, in any one of the first to twenty-second embodiments, the cover may include an exhaust portion, and the exhaust portion may be disposed radially further outward than the electrode connection portion.

[0042] According to the twenty-fourth embodiment, in the twenty-third embodiment, the cover may have a support surface that extends radially flat and is radially more inward than the mating surface, the electrode connection portion may be disposed at a position that is axially recessed and radially more inward than the support surface, and the vent portion may be disposed on the support surface.

[0043] According to the twenty-fifth embodiment, in any one of the first to twenty-fourth embodiments, a first electrode terminal may be provided at the bottom of the battery casing. The first electrode terminal is electrically insulated from the bottom and fixed to the bottom, and the first electrode of the electrode assembly may be electrically connected to the first electrode terminal.

[0044] According to the twenty-sixth embodiment, a battery pack is provided, which includes battery cells according to any one of the first to twenty-fifth embodiments.

[0045] According to the twenty-seventh embodiment, a vehicle is provided that includes a battery pack according to the twenty-sixth embodiment.

[0046] Beneficial effects

[0047] The battery cell according to the embodiments of this disclosure can have excellent welding strength due to the large contact area between the battery casing and the cover.

[0048] Specifically, in the battery cell according to the embodiments of the present disclosure, when the battery casing and the cover are interference-fitted, the battery casing deforms according to the shape of the cover, and the shape of the cover is designed to minimize the gap between it and the deformed battery casing, so that the weld strength between the battery casing and the cover can be excellent.

[0049] According to embodiments of the present disclosure, a battery cell with a novel appearance can be provided by providing a novel interference fit connection between the battery casing and the cover.

[0050] According to embodiments of this disclosure, the battery cell can ensure economic feasibility in terms of manufacturing processes and costs by omitting the current collector.

[0051] According to embodiments of this disclosure, the battery cell can prevent electrolyte leakage by welding the battery casing and cover. Additionally, this can reduce the occurrence of product defects.

[0052] However, the effects obtained through this disclosure are not limited to those described above, and other technical effects not mentioned herein will be clearly understood by those skilled in the art based on the following description of this disclosure. Attached Figure Description

[0053] The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the foregoing disclosure, serve to provide a further understanding of the technical features of the present disclosure; therefore, the present disclosure is not to be construed as limited to the drawings.

[0054] Figure 1 A battery casing according to an embodiment of the present disclosure is shown schematically.

[0055] Figure 2 An exploded perspective view of an electrode assembly according to an embodiment of the present disclosure is shown schematically.

[0056] Figure 3 A laminate of an electrode assembly according to an embodiment of the present disclosure is shown schematically.

[0057] Figure 4 An electrode assembly manufactured by winding the laminate of the electrode assembly into a core form, according to an embodiment of the present disclosure, is illustrated schematically.

[0058] Figure 5 An electrode assembly manufactured by winding the laminate of the electrode assembly into a core form, according to an embodiment of the present disclosure, is illustrated schematically.

[0059] Figure 6 The illustration schematically shows an embodiment of the present disclosure in which a current collector is attached to one surface of a wound-core electrode assembly and not attached to the other surface.

[0060] Figure 7 The illustration schematically shows an embodiment of the present disclosure in which a current collector is attached to one surface of a wound-core electrode assembly and not attached to the other surface.

[0061] Figure 8 The process of accommodating an electrode assembly into a battery casing according to an embodiment of the present disclosure is illustrated schematically.

[0062] Figure 9 The process of welding the first electrode terminal and the current collector according to an embodiment of the present disclosure is illustrated schematically.

[0063] Figure 10 The process of pressing the cover into the battery housing according to an embodiment of the present disclosure is illustrated schematically.

[0064] Figure 11 The cover is schematically shown according to an embodiment of the present disclosure.

[0065] Figure 12 The cover is schematically shown according to an embodiment of the present disclosure.

[0066] Figure 13 A cross-section of the cover according to an embodiment of the present disclosure is shown schematically.

[0067] Figure 14 The illustration schematically shows the state in which the cover is pressed into the battery housing according to an embodiment of the present disclosure.

[0068] Figure 15 An enlarged view schematically illustrates the engagement of a cover that is press-fitted into a battery housing according to an embodiment of the present disclosure.

[0069] Figure 16 An enlarged view schematically illustrates the engagement of a cover that is press-fitted into a battery housing according to an embodiment of the present disclosure.

[0070] Figure 17 The cap is schematically attached to the cover according to an embodiment of the present disclosure.

[0071] Figure 18 A battery pack according to an embodiment of the present disclosure is illustrated schematically.

[0072] Figure 19 A vehicle according to an embodiment of the present disclosure is shown schematically. Detailed Implementation

[0073] It should be understood that the terms used in the specification and appended claims should not be construed as limited to their general or dictionary meanings, but rather are interpreted according to their meanings and concepts corresponding to the technical aspects of this disclosure, based on the principle that inventors are allowed to appropriately define terms for the best interpretation.

[0074] The terminology used herein is for describing exemplary embodiments only and is not intended to limit this disclosure. Unless the context clearly indicates otherwise, singular expressions include plural expressions.

[0075] <Definition>

[0076] Throughout the specification, when a component is referred to as "including" a part, it means that it may include other parts, rather than excluding other parts, unless otherwise expressly stated.

[0077] Throughout this instruction manual, unless otherwise expressly stated, each component may be singular or plural.

[0078] Throughout this specification, when any configuration is positioned on the “upper (or lower)” or “top (or bottom)” of a component, it means not only that any configuration is positioned to contact the upper (or lower) surface of the component, but also that other configurations may be inserted between the component and any configuration positioned above (or below) the component.

[0079] Throughout the specification, when describing a component as “connected,” “joined,” or “in contact” with another component, the components may be directly connected or in contact with each other, but it should be understood that other components may be “inserted” between each component, or each component may be “connected,” “joined,” or “in contact” with another component.

[0080] Throughout the specification, when “A and / or B” is mentioned, it means A, B or both A and B unless otherwise expressly stated, and when “C to D” is mentioned, it means C or more and D or fewer unless otherwise expressly stated.

[0081] Throughout the specification, the axial direction refers to the axial direction extending from the axis of the winding center that forms the core-type electrode assembly, the radial direction refers to the direction closer to or further away from the winding axis, and the circumferential direction refers to the direction around the axis.

[0082] The embodiments described in this specification and the configurations shown in the accompanying drawings are only some of the most preferred embodiments of this disclosure and are not intended to fully represent the technical aspects of this disclosure. Therefore, it should be understood that various equivalents and modifications may be made thereto when this application is filed.

[0083] <Battery casing and first electrode terminal>

[0084] In the following text, reference will be made to Figures 1 to 17 The structure of a battery cell according to an embodiment of the present disclosure is described.

[0085] The battery cell disclosed herein can be, for example, a cylindrical battery cell with a form factor ratio (defined as a value obtained by dividing the diameter of a cylindrical battery cell by its height, i.e., the ratio of diameter Φ to height H) greater than about 0.4.

[0086] Here, the shape factor refers to the values ​​representing the diameter and height of the cylindrical battery cell. The cylindrical battery cell can be, for example, a 46110 cell, a 48750 cell, a 48110 cell, a 48800 cell, or a 46800 cell. In the shape factor value, the first two digits indicate the cell's diameter, the last two digits indicate the cell's height, and the last digit, 0, indicates that the cell's cross-section is circular.

[0087] The battery cell can be a cylindrical battery cell with a generally cylindrical shape having a diameter of about 46 mm, a height of about 110 mm, and a form factor ratio of 0.418.

[0088] According to another embodiment, the battery cell can be a cylindrical battery cell with a generally cylindrical shape having a diameter of about 48 mm, a height of about 75 mm, and a form factor ratio of 0.640.

[0089] According to another embodiment, the battery cell can be a cylindrical battery cell with a generally cylindrical shape having a diameter of about 48 mm, a height of about 110 mm, and a form factor ratio of 0.418.

[0090] According to another embodiment, the battery cell can be a cylindrical battery cell with a generally cylindrical shape having a diameter of about 48 mm, a height of about 80 mm, and a form factor ratio of 0.600.

[0091] According to another embodiment, the battery cell can be a cylindrical battery cell with a generally cylindrical shape having a diameter of about 46 mm, a height of about 80 mm, and a form factor ratio of 0.575.

[0092] Reference Figure 1 The battery housing 10 disclosed herein includes a cylindrical sidewall portion 11, a bottom 12 connected to one axial end of the sidewall portion 11, and an open end provided at the other axial end of the sidewall portion 11.

[0093] The bottom 12 and the side wall portion 11 can be manufactured by forming a conductive metal sheet through a deep drawing process, and then trimming the front end of the side wall portion 11 with a punch while it is held in place by a blank holder.

[0094] Alternatively, the bottom 12 and the side wall portion 11 can be manufactured by forming a conductive metal sheet through a deep drawing process, supporting the front end of the side wall portion 11 with a jig, and then machining it perpendicular to the bottom 12 using a cutting device.

[0095] In embodiments of this disclosure, the conductive metal sheet may include, for example, aluminum, steel, stainless steel, etc., but is not limited thereto.

[0096] In embodiments of this disclosure, when the battery housing 10 is manufactured by trimming, the battery housing 10 may include: a first vertical portion forming a portion of the inner peripheral surface of the sidewall portion; an inclined portion forming the remainder of the inner peripheral surface of the sidewall portion and extending inclinedly outward in the axial direction from the end of the first vertical portion, such that the length of the radial peripheral portion increases; a horizontal portion extending horizontally outward in the radial direction from the end of the inclined portion; and a second vertical portion connected to the end of the horizontal portion and forming the outer surface of the sidewall portion.

[0097] In embodiments of this disclosure, when the inclined portion is included, the cover 40 can be easily inserted axially into the battery housing 10 via the inclined portion when it is interference-fitted into the opening end.

[0098] In embodiments of this disclosure, the height of the inclined portion can be in the range of 0.1 mm to 0.4 mm, or 0.15 mm to 0.3 mm.

[0099] In embodiments of this disclosure, the sidewall portion 11 of the battery housing 10 may have a chamfered shape with the edge on the open end side being chamfered, a rounded shape, or an angled shape in which the horizontal and vertical portions of the sidewall portion 11 are perpendicular to each other by being processed by a cutting device.

[0100] Specifically, in embodiments of this disclosure, 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 chamfer or a rounded shape.

[0101] A hole is formed in the central portion of the bottom 12, and the first electrode terminal 13 can be fitted into this hole. The first electrode terminal 13 can be riveted and fixed to the bottom 12, and a terminal washer 14 is inserted between the first electrode terminal 13 and the bottom 12. The terminal washer 14 can be inserted between the first electrode terminal 13 and the bottom 12 to seal the inside and outside of the battery housing 10, thereby preventing electrolyte leakage and electrically insulating the first electrode terminal 13 from the bottom 12.

[0102] However, the connection method between the first electrode terminal 13 and the bottom 12 is not limited to this. For example, various other fixing methods can be applied, such as bolt-nut connection, glass sealing, or chrome coating & PP-MAH thermal bonding, as long as the structure can provide a seal between the first electrode terminal 13 and the bottom 12 and electrically insulate the first electrode terminal 13 from the bottom 12.

[0103] The first electrode terminal 13 may have a first polarity, and the battery casing 10 may have a second polarity. Therefore, both the bottom 12 of the battery casing 10 and the side wall portion 11 connected to the bottom 12 may have a second polarity.

[0104] Therefore, 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 battery housing 10 may have both a busbar connected to the first electrode terminal 13 and a busbar connected to the second electrode terminal 15 located at one axial end of the battery housing 10.

[0105] In embodiments of this disclosure, the first electrode terminal 13 can be the positive terminal, and the second electrode terminal 15 can be the negative terminal. Of course, the reverse is also possible.

[0106] <Electrode Assembly>

[0107] In embodiments of this disclosure, the electrode assembly 20 is housed within the battery casing 10. The electrode assembly 20 is manufactured in the form of a core by means of: preparing as... Figure 2 The first electrode 21, the second electrode 22, and the diaphragm 28, which extend along the length direction and have predetermined widths, are shown, and are transmitted through, as... Figure 3 The first electrode 21, the diaphragm 28, the second electrode 22 and the diaphragm 28 are laminated in the order shown to form a laminate, and then the laminate is wound around a mandrel.

[0108] In embodiments of this disclosure, the first electrode 21 can be a positive electrode, and the second electrode 22 can be a negative electrode. Of course, the reverse is also possible.

[0109] In embodiments of this disclosure, the first electrode 21 and the second electrode 22 are manufactured in the form of sheets. The electrode sheets can be manufactured by coating an active material layer 24 onto the surface of a metal foil 23. The electrode sheets can have a coated portion 25 with the active material layer 24 and an uncoated portion 26 without the active material layer 24. The positive electrode sheet can have an uncoated portion 26 on one side in the width direction, and the negative electrode sheet can have an uncoated portion 26 on the other side in the width direction.

[0110] In embodiments of this disclosure, a positive electrode can be manufactured by coating a positive electrode current collector with a composition for forming a positive electrode, the composition comprising a positive electrode active material, a binder, a conductive agent, and a solvent.

[0111] In embodiments of this disclosure, the positive electrode active material can be any conventional positive electrode active material that can be used as the positive electrode in a conventional electrochemical device. For example, the positive electrode active material can be lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium iron oxide, or a lithium composite oxide combining any of these.

[0112] At this point, the positive electrode active material can be included in an amount of 80 wt% to 99 wt%, preferably 85 wt% to 98 wt%, based on the total weight of the solid contents of the composition used to form the positive electrode. When the content of the positive electrode active material meets the above range, excellent capacity characteristics can be exhibited.

[0113] There are no particular restrictions on the positive current collector, as long as it is conductive and does not cause chemical changes in the battery. Examples of suitable materials for the positive current collector may include stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel with surface treatments of carbon, nickel, titanium, silver, etc.

[0114] Binders are components that facilitate the bonding of active materials and conductive agents, as well as their bonding with current collectors, and are typically added in amounts from 1 wt% to 30 wt% based on the total weight of the solid contents of the composition used to form the positive electrode. Examples of binders may include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene propylene diene monomer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluororubber, and various copolymers.

[0115] Conductive agents can be added in amounts typically from 1 wt% to 30 wt% based on the total weight of the solid contents of the composition used to form the positive electrode.

[0116] There are no particular limitations on conductive agents, as long as they are conductive without causing chemical changes in the battery. Examples of conductive agents can include: graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermally cracked black; conductive fibers such as carbon fibers or metal fibers; fluorocarbon compounds; metal powders such as aluminum powder and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides, such as titanium oxide; and conductive materials such as polystyrene derivatives. Specific examples of commercially available conductive agents include acetylene black series products such as those from Chevron Chemical, Denka Singapore Private Limited, or Gulf Oil, Ketjen black EC series products (from Armak), Vulcan XC-72 (from Cabot), and Super P (from Timcal).

[0117] In addition, if necessary, the positive electrode active material layer may optionally also include a dispersant.

[0118] Dispersants can be used without any particular restrictions, as long as they are used as dispersants for the positive electrode, and, for example, aqueous or organic dispersants can be used selectively as needed. Preferably, examples of dispersants may include: cellulose-based compounds, polyoxyethylene, polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl acetal, polyvinyl ether, polyvinyl sulfonic acid, polyvinyl chloride (PVC), polyvinylidene fluoride, chitosan, starch, linear starch, polyacrylamide, poly-N-isopropylacrylamide, poly-N,N-dimethylacrylamide, polyethyleneimine, polyoxyethylene, poly(2-methoxyethoxyethylene), poly(acrylamide-co-diallyldimethylammonium chloride), acrylonitrile / butadiene / styrene (ABS) polymers, mixtures of acrylonitrile / styrene / acrylate (ASA) polymers and propylene carbonate, styrene / acrylonitrile (SAN) copolymers, methyl methacrylate / acrylonitrile / butadiene / styrene (MABS) polymers, styrene-butadiene rubber, nitrile rubber, and fluororubber, and any one or mixtures of two or more of these may be used. Hydrogenated nitrile butadiene rubber (H-NBR) can be used. When the positive electrode active material layer also includes a dispersant, the dispersibility of the components of the positive electrode active material layer, especially the conductive agent, can be improved, but this is not the only possibility.

[0119] In addition, the solvent may be a solvent commonly used in the art, such as dimethyl sulfoxide (DMSO), isopropanol, N-methylpyrrolidone (NMP), acetone or water, and one or more of these solvents may be used alone or as a mixture of two or more thereof. In view of the coating thickness and manufacturing yield of the slurry, the amount of the solvent used is sufficient to dissolve or disperse the positive electrode active material, the conductive agent and the binder, and obtain a viscosity that can achieve excellent thickness uniformity during the subsequent coating for manufacturing the positive electrode.

[0120] The negative electrode according to the present disclosure can be manufactured by coating a composition for forming a negative electrode, which includes a negative electrode active material, a binder, a conductive agent and a solvent, onto a negative current collector. In addition, if necessary, the composition for forming a negative electrode may optionally further include a dispersant.

[0121] As the negative electrode active material, a compound capable of reversibly intercalating and deintercalating lithium can be used. Preferably, the negative electrode may also use silicon-based negative electrode active materials exhibiting high capacity characteristics, carbon-based negative electrode active materials, and the following negative electrode active materials, for example, metal composite oxides such as Li x Fe₂O₃ (0≤x≤1), Li x WO₂ (0≤x≤1), Sn x Me 1-x Me' y O z (Me: Mn, Fe, Pb or Ge; Me': Al, B, P, Si, elements of Groups 1, 2 and 3 of the Periodic Table of the Elements, halogens; 0<x≤1; 1≤y≤3; 1≤z≤8); lithium metal; lithium alloys; tin-based alloys; metal oxides such as SnO, SnO₂, PbO, PbO₂, Pb₂O₃, Pb₃O₄, Sb₂O₃, Sb₂O₄, Sb₂O₅, GeO, GeO₂, Bi₂O₃, Bi₂O₄ and Bi₂O₅; conductive polymers, for example, polyacetylene; Li-Co-Ni based materials; titanium oxides; and lithium titanium oxides. The silicon-based negative electrode active material may include at least one selected from the group consisting of Si, SiO x (0.1<x<5), Si-metal alloys, silicon oxide particles doped or chemically bonded with a metal such as Mg (SiO x , 0.1<x<5), and alloys of Si and SiO x (0.1<x<5). The carbon-based negative electrode active material may include at least one selected from the group consisting of natural graphite, artificial graphite, amorphous hard carbon, low-crystalline soft carbon, carbon black, acetylene black, Ketjen black, Super P, graphene and fibrous carbon.

[0122] There are no particular limitations on the negative electrode current collector, as long as it has high conductivity without causing chemical changes in the battery. Examples of suitable materials for the negative electrode current collector include copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., and aluminum-cadmium alloys. Furthermore, the negative electrode current collector can typically have a thickness from 3 μm to 500 μm, and similar to the positive electrode current collector, fine irregular structures can be formed on its surface to enhance the adhesion of the negative electrode active material. For example, the negative electrode current collector can be used in various forms, such as membranes, sheets, foils, meshes, porous bodies, foams, and nonwoven fabrics.

[0123] The conductive agent, binder, solvent, or dispersant included in the composition for forming the negative electrode may be used without particular limitation, as long as they are generally used in the composition for forming the electrode, and for example, the conductive agent, binder, solvent, or dispersant specified in the composition for forming the positive electrode described above may be used.

[0124] In embodiments of this disclosure, the uncoated portion 26 may be exposed or protrude from the laminate in the width direction, such as... Figure 2 and Figure 3 As shown. The uncoated portion 26 itself can be used as an electrode tab.

[0125] In embodiments of this disclosure, cuts may be formed at predetermined intervals in the uncoated portion 26 to form flag-shaped cut tabs 27.

[0126] In embodiments of this disclosure, the notched tab 27 can be in the shape of an equilateral trapezoid, such as... Figure 2 and Figure 3 As shown. However, they can be various shapes, such as semicircles, semi-ovals, triangles, rectangles, and parallelograms.

[0127] In embodiments of this disclosure, the slit tabs 27 may have the same width arranged along the length direction. However, the width of the slit tabs may gradually or progressively increase from the core side toward the outer periphery.

[0128] In embodiments of this disclosure, the height of the cut tabs 27 can gradually increase from the winding side toward the radially outer peripheral side. However, the height of these cut tabs 27 can be made constant or gradually decrease.

[0129] In embodiments of this disclosure, the notched tab 27 may be omitted from a predetermined section of the radially inner end and a predetermined section of the radially outer end of the uncoated portion 26. However, it is apparent that the notched tab may not be removed from the radially inner end of the uncoated portion, and the notched tab may not be removed from the radially outer end of the uncoated portion.

[0130] In embodiments of this disclosure, the cut-out tabs 27 of the wound-core type electrode assembly 20 can be bent and flattened radially. The cut-out tabs 27 can be bent radially inward or outward. For example, as... Figure 4 and Figure 5 As shown, the notched tab 27 can bend radially inward.

[0131] In embodiments of this disclosure, the slit tabs 27 may be bent one after another during the winding of the laminate to form a core-type electrode assembly 20. Alternatively, the slit tabs 27 may be bent all at once after the laminate has been wound to form the core-type electrode assembly.

[0132] In embodiments of this disclosure, the notched tabs 27 of the first electrode 21 and the notched tabs 27 of the second electrode 22, which are radially bent and overlapped in this manner, can each provide a plane substantially perpendicular to the axial direction at both axial ends of the electrode assembly 20, such as... Figure 5 As shown.

[0133] In embodiments of this disclosure, the current collector 31 can engage with a substantially flat surface provided by bending the cut-out tabs 27 exposed at the two axial ends of the electrode assembly 20, such as Figure 6 As shown.

[0134] In embodiments of this disclosure, the manifold 31 can be manufactured by stamping, trimming, perforating, and bending metal sheets.

[0135] In embodiments of this disclosure, reference is made to Figure 6 The current collector 31 may include a terminal connection portion 32 extending radially from a central portion, an annular portion 33 connecting the centrifugal edge of the terminal connection portion 32 in the circumferential direction, and an electrode connection portion 34 extending from the annular portion 33 toward the center and not connected to the terminal connection portion 32. The central portion of the terminal connection portion 32 may cover at least a portion of the hollow core of the electrode assembly 20.

[0136] In embodiments of this disclosure, before the electrode assembly 20 is placed into the battery housing 10, the electrode connection portion 34 can be joined to the cut tab 27 of the first electrode 21 of the electrode assembly 20 by means of laser welding or the like.

[0137] In embodiments of this disclosure, reference is made to Figure 7 The current collector may not be connected to the cutout tab 27 of the second electrode 22 of the electrode assembly 20. Of course, this disclosure is not limited to the structure in which the current collector is not connected to the cutout tab 27 of the second electrode 22.

[0138] In embodiments of this disclosure, such as Figure 8 and Figure 9As shown, the electrode assembly 20 can be housed in the battery housing 10 when the current collector 31 is aligned to face the bottom 12 of the battery housing 10. At this time, an insulator 19 can be inserted between the current collector 31 and the bottom 12 of the battery housing 10 to electrically insulate the current collector 31 from the bottom 12.

[0139] In embodiments of this disclosure, the terminal connection portion 32 of the current collector 31 can be joined to the first electrode terminal 13 fixed to the battery casing 10 by resistance welding, ultrasonic welding, or laser welding. For example... Figure 9 As shown, the welding equipment for forming a weld between the current collector 31 and the first electrode terminal 13 can pass through the hollow core of the electrode assembly 20 from the other axial end of the electrode assembly 20 and approach the rear surface of the center of the terminal connection portion 32 of the current collector 31 to perform welding. Obviously, the current collector 31 and the first electrode terminal 13 can also be joined by brazing or soldering. That is, the current collector 31 and the first electrode terminal 13 can be joined by various methods, as long as they can be electrically connected and fixed to each other.

[0140] Reference Figure 10 With the electrode assembly 20 housed within the battery casing 10 and the first electrode 21 connected to the first electrode terminal 13, the notched tab 27 of the second electrode 22 can be directly connected to the cover 40, which is press-fitted through the open end of the battery casing 10. Therefore, the second electrode 22 is electrically connected to the cover 40 via a weld between the notched tab 27 and the cover 40. Clearly, in addition to welding, other joining methods such as brazing or soldering can also be applied to the notched tab 27 and the cover 40.

[0141] In embodiments of this disclosure, the edge of the cover 40 is joined to the side wall portion 11 of the battery housing 10 for electrical connection and sealing. Therefore, the second electrode 22 can be electrically connected to the cover 40 and the battery housing 10. Various methods that allow for electrical connection and sealing (e.g., fusion welding, brazing, and soldering) can be applied to the treatment of the joint M between the cover 40 and the battery housing 10. This will be described in detail later.

[0142] <cover>

[0143] In the following text, reference will be made to Figures 11 to 17 The structure of the cover and the battery cell using the cover is described in this disclosure.

[0144] In embodiments of this disclosure, the cover 40 can be manufactured by pressing a circular metal sheet.

[0145] In embodiments of this disclosure, the cover 40 has a generally disc-shaped form in order to block the opening end of the battery housing 10.

[0146] In embodiments of this disclosure, such as Figure 13 As shown, the cover 40 may include, from the radially outer side to the inner side, a mating surface 48, a curved surface 47, a first inclined surface 46, a supporting surface 45, a second inclined surface 49, and an electrode connection portion 41.

[0147] In embodiments of this disclosure, such as Figures 11 to 13 As shown, the cover 40 can have a cross-sectional shape that is asymmetrical relative to the radial inner center in the A'A direction. That is, as... Figure 13 As shown, the cover 40 may include a mating surface 48, a curved surface 47, a supporting surface 45, and a bridging element 44 from the radially outer to the inner side.

[0148] In embodiments of this disclosure, a mating surface 48 is disposed on the radial outer edge of the cover 40, and the outer peripheral surface of the mating surface 48 extends to contact the inner peripheral surface of the sidewall portion of the battery housing 10. Specifically, the mating surface 48 is inclined relative to the axial direction, thereby increasing the length of the radial peripheral portion, and at least a portion of the mating surface 48 and at least a portion of the inner peripheral surface of the sidewall portion 11 (that is, at least a portion of the protrusion 11a) contact and engage with each other.

[0149] In embodiments of this disclosure, the cover 40 covers the open end of the battery housing 10, and the cover 40 can be pressed into place through the open end. Thereafter, at least a portion of the mating surface 48 and at least a portion of the protrusion 11a can be joined for electrical connection and sealing. This joining can be achieved by various methods that allow electrical connection and sealing, such as welding, particularly butt welding, brazing, and soldering, and preferably laser welding.

[0150] In embodiments of this disclosure, the thickness of the mating surface 48 is greater than the thickness of the sidewall portion 11 of the battery housing 10 facing the mating surface 48, or the hardness of the mating surface 48 of the cover 40 is greater than the hardness of the sidewall portion 11 of the battery housing 10. Therefore, the cover 40 is assembled to the battery housing 10 by an interference fit, such that the sidewall portion 11 of the battery housing 10 on the open end side has a radially outwardly projecting protrusion 11a, and at least a portion of the mating surface 48 contacts at least a portion of the inner circumferential surface of the protrusion 11a. At this time, compared to before the interference fit, the mating surface 48 can have a reduced axial angle (θ), thereby further increasing the contact area between the mating surface 48 and the protrusion 11a.

[0151] In embodiments of this disclosure, the roundness (or smoothness) of the cover 40 is better than the roundness of the sidewall portion 11 on the opening end side of the battery housing 10. Therefore, when the cover 40 is assembled to the battery housing 10 by an interference fit, the sidewall portion 11 on the opening end side of the battery housing 10 can have a roundness similar to that of the cover 40.

[0152] In embodiments of this disclosure, there may be substantially no gap between at least a portion of the mating surface 48 and the inner peripheral surface of the protrusion 11a. Here, "substantially" means the error difference in the measuring device when measuring the gap between the cover 40 and the sidewall portion 11. For example, the gap between at least a portion of the mating surface 48 and the inner peripheral 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 mating surface 48, or they may be in complete contact with each other.

[0153] In embodiments of this disclosure, the gap between at least a portion of the mating surface 48 and the inner peripheral surface of the protrusion 11a can 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).

[0154] In embodiments of this disclosure, as described above, when manufacturing the battery housing 10 by trimming, the battery housing 10 may include: a first vertical portion that forms part of the inner peripheral surface of the sidewall portion based on the case where the cover 40 is not pressed into place; an inclined portion that forms the remaining portion of the inner peripheral surface of the sidewall portion and extends inclinedly outward in the axial direction from the end of the first vertical portion, thereby increasing the length of the radial peripheral portion; a horizontal portion that extends horizontally outward in the radial direction from the end of the inclined portion; and a second vertical portion that connects to the end of the horizontal portion and forms the outer surface of the sidewall portion.

[0155] Furthermore, in embodiments of this disclosure, when as Figure 16 When the cover 40 is pressed into the trimmed battery housing 10, the protrusion 11a may also include an inclined portion 11b at the end on the opening side, in which the length of the radial peripheral portion increases outward along the axial direction.

[0156] In this configuration, the mating surface 48 engages with the inner circumferential surface of the protrusion 11a that connects to the inclined portion 11b, such that the gap between at least a portion of the mating surface 48 and the inner circumferential surface of the protrusion 11a can be substantially nonexistent, or can be 10 μm or less. That is, the inclined portion 11b and the mating surface 48 can remain in contact with each other. Furthermore, due to the presence of the inclined portion 11b, as described above, when the cover 40 is interference-fitted into the battery housing 10, the cover 40 can be easily inserted into the battery housing 10.

[0157] In embodiments of this disclosure, the mating surface 48 may have a slope of 1° to 30° or 5° to 25° relative to the axial direction. For example, the mating surface 48 may have a shape similar to a truncated cone side surface rather than a cylindrical side surface. In this case, the angle of the mating surface 48 relative to the axial direction can be obtained by measuring the angle (θ) formed between the cross-section of the mating surface 48 and the winding axis, such as... Figure 13 As shown. Alternatively, the angle formed between the mating surface 48 and the winding axis can be obtained by measuring the angle formed between a plane tangent to any point on the mating surface 48 and the winding axis.

[0158] In embodiments of this disclosure, the thickness of the mating surface 48 can be greater than the thickness of the sidewall portion 11. Because the mating surface 48 is thicker than the sidewall portion 11, when the cover 40 is interference-fitted into the battery housing 10, the sidewall portion of the battery housing 10 on the open end side can more easily protrude radially outward.

[0159] In embodiments of this disclosure, the thickness of the mating surface 48 can 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.

[0160] In embodiments of this disclosure, the thickness of the sidewall portion 11 can be in the range of 0.35 mm to 0.45 mm, or 0.37 mm to 0.42 mm. However, in this case, the thickness of the mating surface 48 can be greater than the thickness of the sidewall portion 11.

[0161] In embodiments of this disclosure, the cover 40 is assembled to the battery housing 10 by an interference fit, such that the sidewall portion 11 of the battery housing 10 on the open end side has as... Figure 14 The protrusion 11a shown is radially outward.

[0162] Specifically, the protrusion 11a can be formed by the deformation of the side wall portion 11 on the open end side of the battery housing 10 when the cover 40 and the battery housing 10 are assembled together by an interference fit. Therefore, the battery housing 10 can have a deformed cylindrical shape, wherein the protrusion 11a is provided on the side wall portion on the open end side.

[0163] In embodiments of this disclosure, the shape of the protrusion 11a may vary depending on the shape of the mating surface 48 of the cover 40, but may be, for example, a partial shape of an ellipsoid or a partial shape of a cone.

[0164] In embodiments of this disclosure, the interference fit amount of the cover 40, based on one side, can be in the range of 30 μm to 250 μm, or 50 μm to 200 μm. In this case, the interference fit amount can refer to half the difference between the outer diameter of the cover 40 and the diameter (or inner diameter) of the inner surface of the battery housing 10 before the interference fit. Because the interference fit amount of the cover 40 satisfies the above range, the connection between the cover 40 and the battery housing 10 can be more excellent, while reducing mechanical damage to the battery cells.

[0165] In embodiments of this disclosure, the curved surface 47 may have a downwardly convex cross-sectional shape that is connected to the lower end of the mating surface 48 of the cover 40 (that is, the axially inner end of the mating surface 48) and extends radially inward as it moves axially inward.

[0166] In embodiments of this disclosure, the curved surface 47 may extend to the point where the slope of the tangent becomes 0 degrees. The point where the slope of the tangent on the curved surface 47 becomes 0 degrees may be a portion extending axially from the curved surface 47 to its innermost side. More preferably, the curved surface 47 may increase in a direction where the slope of the tangent increases beyond 0 degrees. In this case, the slope of the curved surface 47 may increase continuously, increase discontinuously, or remain constant.

[0167] Furthermore, the curved surface 47 can be spaced apart from the electrode assembly 20. For example, a separation distance can be ensured between the curved surface 47 and the electrode assembly 20. Because the separation distance is ensured, welding heat will not be transferred to the electrode assembly during seam welding, and physical damage to the electrode assembly, such as cracks or deformation, can be prevented, especially in the uncoated areas.

[0168] In embodiments of this disclosure, the curved surface 47 may have a U-shaped bend to enhance weldability during seam welding. The shape of the curved surface 47 may be adapted to press the cover 40 through the open end of the battery housing 10. Furthermore, the insertion depth of the cover 40 may not be adjusted due to interference between the curved surface 47 and the electrode assembly 20.

[0169] In embodiments of this disclosure, a first inclined surface 46 may be disposed between a curved surface 47 and a supporting surface 45. As the first inclined surface 46 moves radially inward, it extends axially outward, and the slope of the first inclined surface 46 may be substantially constant or vary to a second slope. For example, the slope of the first inclined surface 46 may be approximately 10° to 50°, such as approximately 50°.

[0170] In embodiments of this disclosure, the first inclined surface 46 and the curved surface 47 can provide a cross-sectional shape that allows the cover 40 to elastically deform radially inward. Therefore, when the cover 40 is pressed into the open end, the deformation of the cover 40 can be slightly altered. Furthermore, in embodiments of this disclosure, because the thickness of the sidewall portion 11 of the battery housing 10 is thinner than the mating surface 48 of the cover 40, the sidewall portion 11 of the battery housing 10 on the open end side is modified to form a protrusion 11a. Even at this time, due to the first inclined surface 46 and the curved surface 47 of the cover 40, the U-shape is compressed and then unfolded, causing the slope (θ) of the mating surface 48 to decrease slightly, and the sidewall portion 11 to protrude radially outward, thereby ensuring radial adhesion between the sidewall portion 11 of the battery housing and the mating surface 48 of the cover. In this process, the mating surface 48 can firmly abut against the sidewall portion without deformation. In this case, tack welding is not required, and the laser used for butt welding does not enter the internal space of the battery housing 10, thus preventing damage to the electrode assembly 20. Furthermore, there is no issue of the welded portion becoming too thin, thus ensuring sufficient weld strength.

[0171] In embodiments of this disclosure, the mating surface 48 can be ensured to be, for example, 0.7 mm or longer.

[0172] In embodiments of this disclosure, the support surface 45, which extends horizontally in the radial direction, is positioned radially inwardly than the curved surface 47 on the cover 40. The support surface 45 is connected to the radially inner end of the first inclined surface 46 and can extend horizontally inwardly from the connection portion.

[0173] In embodiments of this disclosure, the surface of the support surface 45 has a flat planar shape, and therefore, when the battery cell is as follows... Figure 2 As shown, when the battery is upright with the cover 40 placed on the bottom, the support surface 45 can be used as the foot of the battery cell.

[0174] In embodiments of this disclosure, reference is made to Figure 14 The axial outer surface of the supporting surface 45 can be positioned further outward in the axial direction than the axial outer end of the mating surface 48. Therefore, even when... Figure 2 When the battery cell is erected with the cover 40 in contact with the bottom, it can also prevent the welded part of the cover 40 and the battery casing 10 from directly contacting the bottom, thereby protecting the welded part.

[0175] In embodiments of this disclosure, the electrode connection portion 41, extending horizontally in the radial direction, is disposed further inward in the radial direction than the support surface 45 on the cover 40. (Refer to...) Figure 14The axial inner surface (i.e., the bottom surface) of the electrode connection portion 41 can be axially further inward than the point with a slope of 0 at the axial inner end of the curved surface 47. In other words, the electrode connection portion 41 can be radially further inward at the axially recessed position than the support surface 45, and the axial inner surface of the electrode connection portion 41 can be axially further inward than the axial inner end of the curved surface 47.

[0176] In embodiments of this disclosure, the pressing depth of the cover 40 into the battery housing 10 can be determined by the connection portion between the electrode connection portion 41 of the cover 40 and the tab of the second electrode 22 of the electrode assembly 20 housed in the battery housing 10. That is, the bottom surface of the electrode connection portion 41 can be configured to be closest to the electrode assembly 20 compared to the remaining bottom surface of the cover 40. In this case, when the electrode connection portion 41 is engaged with the electrode assembly 20, the remaining portion of the cover 40, excluding the electrode connection portion 41, can be spaced apart from the electrode assembly 20.

[0177] In embodiments of this disclosure, the electrode connection portion 41 can be in close contact with the tab of the second electrode 22 of the electrode assembly 20, and they can be joined together. Their joining can be achieved by welding. The weld portion W of the electrode connection portion 41 and the tab 27 of the second electrode 22 can be formed by laser light irradiating the axially outer surface of the electrode connection portion 41 from the axially outer side, such as... Figure 17 As shown. The laser can irradiate in a scanning manner along the radial direction to form a weld portion W that extends longer along the radial direction. The electrode connection portion 41 can be connected to the electrode assembly 20 face-to-face. The electrode connection portion 41 can be connected to the metal foil 23.

[0178] Thus, the cover 40 serves as a cover to close the opening end of the battery casing 10, and also functions as a current collector for the second electrode 22. Therefore, the cover 40 can have a second polarity, and the side wall portion 11 welded to the cover 40 and the bottom portion 12 connected to the side wall portion 11 can also have a second polarity.

[0179] In embodiments of this disclosure, the electrode connection portion 41 may extend radially outward to at least half the radius of the battery housing 10. Preferably, the electrode connection portion 41 may extend to at least 0.7 times the radius of the battery housing 10. The electrode connection portion 41 may extend radially flat.

[0180] In embodiments of this disclosure, the electrode connection portion 41 may occupy at least 50% of the total area of ​​the battery casing 10.

[0181] In embodiments of this disclosure, since the electrode connection portion 41 of the cover 40 can have a bottom surface shape that extends horizontally with sufficient width, the welding area with the tab of the second electrode 22 can be adequately ensured. In this case, the height of the bottom surface of the electrode connection portion 41 can be lower than the height of the lower end of the curved surface 47. That is, the electrode connection portion 41 can protrude more inwardly in the axial direction than the curved surface 47. Then, the lower end of the curved surface 47 can be spaced apart from the electrode assembly 20 housed inside the battery casing 10 by a separation distance in the axial direction, while ensuring that the bottom surface of the electrode connection portion 41 can be in close contact with the electrode assembly 20.

[0182] In embodiments of this disclosure, the current collector 31 can be electrically connected to the tab of the second electrode 22, and the electrode connection portion 41 can be electrically connected to the current collector 31 to the tab of the second electrode 22. That is, the current collector 31 can be soldered to the tab of the second electrode 22, and the electrode connection portion 41 of the cover 40 can be soldered to the current collector 31.

[0183] In another embodiment of this disclosure, the electrode connection portion 41 can be directly engaged with the tab of the second electrode 22 to be electrically connected.

[0184] Specifically, a structure can exist in which the tab of the second electrode 22 is welded to the electrode connection portion 41 of the cover 40 for electrical connection without a separate current collector 31. That is, since the cover 40 can be coupled to the battery housing 10 to cover the opening end of the battery housing 10 and can be simultaneously electrically connected to the electrode assembly 20, a separate current collector 31, such as a negative current collector 31, is not required. In other words, the cover 40 of this disclosure can be configured as a so-called integrated cover capable of performing the function of a current collector together. Therefore, the joint between the cover 40 and the battery housing 10 is simplified, and a current collector 31 is not required when the electrode assembly 20 is electrically connected to the cover 40. This reduces the number of components and assembly time, and ensures more internal volume, thereby further increasing energy density.

[0185] In embodiments of this disclosure, the junction between the electrode connection portion 41 and the tab of the second electrode 22 can extend radially. That is, the electrode connection portion 41 can extend toward the flat portion 43 and the support surface 45. Specifically, the electrode connection portion 41 can extend centripetally toward the flat portion 43, and the electrode connection portion 41 can extend radially toward the support surface 45. In this case, the weld length (LFW, cover foil tab weld) between the electrode connection portion 41 and the metal foil 23 can be ensured to be longer, thereby reducing the internal resistance of the battery cell.

[0186] In embodiments of this disclosure, multiple electrode connection portions 41 are provided, which can be arranged radially relative to the center of the cover 40 and at equal intervals in the circumferential direction.

[0187] In embodiments of this disclosure, three electrode connection portions 41 may be provided at 120° intervals.

[0188] In embodiments of this disclosure, three electrode connection portions 41 may be provided. When three electrode connection portions 41 are provided, the multiple electrode connection portions 41 can form a plane, thereby more easily ensuring the stable flatness of the electrode assembly 20. In addition, the cover 40 is ensured to adhere by the welding position of the cut tab 27 that only partially contacts the second electrode, and it can also ensure that the cover 40 is resistant to bulging due to the internal pressure of the battery cell.

[0189] In embodiments of this disclosure, the cover 40 may further include at least one bridging member 44. Multiple bridging members 44 may be provided, for example, three. The bridging member 44 extends radially from the flat portion 43. The bridging member 44 may be configured to separate two adjacent electrode connections 41. The bridging member 44 extends from the flat portion 43 toward the mating surface 48.

[0190] In embodiments of this disclosure, the plurality of electrode connections 41 can be more reliably separated and spaced apart by bridging members 44. In this way, bridging members 44 can enhance the rigidity of the cover 40.

[0191] In embodiments of this disclosure, the upper surface of the bridging member 44 may be formed more outward in the axial direction than the upper surface of the electrode connection portion 41, but more inward in the axial direction than the upper surface of the flat portion 43. When the bridging member 44 is formed in this manner, the rigidity of the cover 40 can be further enhanced.

[0192] In embodiments of this disclosure, the protrusion height of the bridging member 44 may correspond to or be lower than the protrusion height of the supporting surface 45.

[0193] In embodiments of this disclosure, the protrusion height of the bridging member 44 corresponds to the protrusion height of the supporting surface 45, such that they can form a single plane. In this case, when the battery housing 10 is erected with its cover 40 facing the floor, the bridging member 44 can also contact the floor together with the supporting surface 45.

[0194] In embodiments of this disclosure, if the height of the bridging member 44 is lower than the height of the support surface 45, the support surface 45 may provide an annular support surface.

[0195] In embodiments of this disclosure, a second inclined surface 49 may be provided between the support surface 45 and the electrode connection portion 41. The second inclined surface 49 extends axially inward as it moves radially inward and has a substantially constant or varying inclination as a third inclination. For example, the absolute value of the third inclination may be approximately 75 degrees. The absolute value of the second inclination of the first inclined surface 46 may be less than the absolute value of the third inclination of the second inclined surface 49. That is, the second inclined surface 49 may be steeper than the first inclined surface 46. Therefore, the radial length of the support surface 45 and the electrode connection portion 41 can be maximized.

[0196] <Liquid Inlet>

[0197] In embodiments of this disclosure, the cover 40 may further include a liquid inlet 42 at the central portion of the cover 40. When the cover 40 covers the open end of the battery housing 10, the liquid inlet 42 may be aligned with the hollow core of the electrode assembly 20 housed in the battery housing 10.

[0198] In embodiments of this disclosure, the liquid inlet 42 may be provided on the bottom surface of the cover 40, that is, on the flat portion 43 that protrudes further outward in the axial direction than the electrode connection portion 41 of the cover 40, such as... Figure 13 As shown, the height of the flat portion 43 may be lower than the height of the supporting surface 45. The flat portion 43 may be connected to the radial edge of the electrode connection portion 41 and has a shape that extends axially outward when it moves radially inward.

[0199] In embodiments of this disclosure, the liquid inlet 42 can be covered and sealed with a cap 50, such as... Figure 17 As shown, the edge of the cap 50 can be sealed and closed with the edge of the liquid inlet 42. The seal can be achieved by seam welding or various other sealing methods known in the art.

[0200] In embodiments of this disclosure, the cap 50 may be in the form of a plug and may be provided by deep-drawing a thin metal sheet with a thickness of 0.3 mm.

[0201] In embodiments of this disclosure, when the liquid inlet 42 is covered and sealed by the cap 50, the height of the cap 50 may also be lower than the height of the support surface 45. The cap 50 is also positioned lower than the support surface 45, and therefore, the cap 50 is not subjected to direct load even when the battery cell is erected with the cap 40 in contact with the floor.

[0202] In embodiments of this disclosure, the flat portion 43 protrudes axially outward more than the bottom of the cap (i.e., the electrode connection portion 41). Therefore, the edge of the liquid inlet 42 is spaced apart from the cut tab 27 of the second electrode 22. Thus, when electrolyte is injected through the liquid inlet 42, and then the cap 50 is covered and joined by welding or the like, the impact of the final joining process of the cap 50 on battery performance (e.g., damage to the separator due to joining heat transferred to the electrode assembly 20) can be minimized.

[0203] Furthermore, in another embodiment of this disclosure, the cover 40 may not include a separate liquid injection port. In this case, when manufacturing the battery cell, if there is no separate liquid injection port at the bottom 12 of the battery housing 10, the electrolyte injection process can be performed first before covering the battery housing 10 with the cover 40.

[0204] However, when the cap 40 also includes a liquid inlet 42, electrolyte can be injected through the liquid inlet 42 even after the cap 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 cap 40 to the battery housing 10 with the electrolyte already injected, it can be ensured that the heat of joining does not affect the electrolyte at all. Furthermore, since the flat portion 43 protrudes upwards even when the periphery of the cap 50 and the liquid inlet 42 are joined, the possibility of the heat of joining the cap 50 affecting the electrolyte can be reduced.

[0205] On the other hand, in embodiments of this disclosure, the liquid inlet 42 formed at the center of the cover 40 can be used as a channel through which a device for welding the first electrode terminal 13 to the manifold 31 of the first electrode 21 can pass.

[0206] Therefore, even after the cover 40 is attached to the battery housing 10, the welding equipment can be introduced into the battery housing 10 through the liquid injection port 42 to attach the first electrode 21 and the first electrode terminal 13.

[0207] In embodiments of this disclosure, the flat portion 43 may further include a mounting portion 43a, which is axially recessed and extends radially flat. In embodiments of this disclosure, the mounting portion 43a can minimize interference with the electrolyte when the cap 50 is welded to the liquid inlet 42.

[0208] In embodiments of this disclosure, the longer the length of the placement portion 43a formed from the liquid injection port 42 to the flat portion 43, the better the weldability with the cap 50 can be achieved.

[0209] <Exhaust Section>

[0210] In embodiments of this disclosure, an exhaust portion 60 may be formed on the upper surface of the cover 40. When a thermal event occurs in the battery cell, the exhaust portion 60 may be disrupted by the internal pressure of the high-temperature exhaust gas, thereby allowing the exhaust gas to be discharged from the battery cell to the outside.

[0211] In embodiments of this disclosure, the cover 40 may include a support surface 45 that extends radially inward and is radially flat compared to the mating surface 48, the electrode connection portion 41 may be disposed at a position radially inward compared to the support surface 45, and the vent portion 60 may be disposed on the support surface.

[0212] In embodiments of this disclosure, the venting portion 60 may be disposed radially outward along the circumferential direction than the electrode connection portion 41. The venting portion 60 may be implemented as a soft or thin portion of the two surfaces of the support surface 45 with cuts made.

[0213] In the embodiments of this disclosure, the venting portion 60 has strength that prevents deformation due to applied force when the cover 40 is pressed into the battery housing 10, and when the internal pressure fluctuates due to short circuits or other reasons occurring inside the battery housing 10, the venting portion 60 is disrupted to separate the electrode connection portion 41 of the cover 40 from the mating surface 48 of the cover 40. Therefore, the electrode connection portion 41 connected to the tab of the second electrode 22 is electrically disconnected from the battery housing 10, and the internal space of the battery housing 10 opens to the outside, allowing the gas causing the internal pressure to be released.

[0214] In embodiments of this disclosure, the vent 60 may be disposed near the central portion of the support surface 45 in the radial direction, so as to be radially spaced from the first inclined surface 46 and the second inclined surface 49. In this case, even if the support surface 45 is subjected to pressure, the pressure is transmitted to the first inclined surface 46 and the second inclined surface 49 and does not affect the vent 60. Therefore, the force applied when the cover 40 is joined to the battery housing 10 and the electrode assembly 20 will not deform the vent 60.

[0215] In embodiments of this disclosure, the exhaust portion 60 may be disposed radially further outward than the bridging member 44. Furthermore, these bridging members 44 may be disposed circumferentially between the electrode connection portions 41.

[0216] Therefore, in the embodiments of this disclosure, when the internal pressure of the battery casing 10 increases, this pressure is smoothly transmitted to the lower space of the bridging member 44 disposed circumferentially between the electrode connection portions 41, and serves as a force for lifting the bridging member 44 upward. Furthermore, the force is concentrated at three points along the circumferential direction. Therefore, the internal pressure of the battery casing 10 can be smoothly transmitted to the vent portion 60, thereby causing a smooth rupture of the vent portion 60.

[0217] In embodiments of this disclosure, the burst pressure of the battery casing 10 can be controlled by controlling the venting portion 60 and its width. For example, the venting portion 60 can be set to operate when the pressure inside the battery casing 10 is 15 kgf / cm². 2 Up to 35 kgf / cm 2 The vent 60 ruptures when the pressure inside the battery casing 10 abnormally increases, allowing all internal gases to escape to the outside. The vent 60 can be formed by making cuts to partially reduce the thickness of the cover 40. The vent 60 can have a thickness gradient. A thickness gradient means that when inspecting the cross-section of the vent 60, it is formed at an angle relative to a predetermined horizontal plane. When the pressure inside the battery casing 10 abnormally increases, the vent 60 ruptures, thereby allowing all internal gases to be released to the outside.

[0218] In embodiments of this disclosure, the vent 60 may be provided on the support surface 45 in the form of a thin-walled portion. However, the vent 60 formed by the cover 40 is not limited to this. For example, the vent may be provided in the cap 50 covering the liquid inlet 42, may be formed by the joint between the liquid inlet 42 and the cap 50, or may be formed by the joint M between the cover 40 and the battery housing 10.

[0219] <Battery and Vehicle>

[0220] Reference Figure 18 The battery cell 72 with the aforementioned cover can be housed within the casing 71 of the battery pack 70. The battery pack 70 can be configured using a battery module as an intermediate component, or it can be configured directly without the battery module shown.

[0221] Because the battery cell 72 itself has a large volume, there are no particular difficulties in realizing the battery pack 70 even without using intermediate structures such as battery modules. Furthermore, because the second electrode is connected via a cover, the battery cell 72 can have low internal resistance and even higher energy density. In addition, the structure of the vent 60 is located within the cover 40, not occupying separate space, thereby further ensuring energy density. Therefore, the energy density of the battery pack 70 equipped with the battery cell 72 can be achieved to be even higher.

[0222] A battery pack 70 with increased energy density in this way can store the same amount of energy while reducing its size and weight. Therefore, as... Figure 19 As shown, if a battery pack 70 using these battery cells 72 is installed in a vehicle such as an electric vehicle 80 that uses electricity as an energy source, the vehicle's range per unit of energy can be further extended.

[0223] It should be understood that the above embodiments are exemplary and not restrictive in all respects, and the scope of this disclosure will be indicated by the described claims rather than the detailed description above. Furthermore, the meaning and scope of the described claims, as well as all variations and modifications derived from equivalent concepts, should be construed as being included within the scope of this disclosure.

[0224] The present disclosure has been described above with reference to the illustrated drawings. However, it is obvious that the present disclosure is not limited to the embodiments and drawings disclosed in this specification, and various modifications can be made by those skilled in the art within the scope of the technical concept of the present disclosure. Furthermore, even if the effects of the configuration according to the present disclosure are not explicitly described in the foregoing description of the embodiments of the present disclosure, it should be understood that the effects predicted by the corresponding configuration are obvious.

Claims

1. A battery cell, the battery cell comprising: A battery housing, the battery housing including a side wall portion, a bottom portion connected to one axial end of the side wall portion, and an open end portion disposed at the other axial end of the side wall portion; An electrode assembly in which a first electrode, a second electrode, and a diaphragm inserted between the first electrode and the second electrode are wound around a winding axis, and the electrode assembly is housed inside the battery casing such that the tab of the second electrode faces the opening end. as well as A cover, which covers the opening end of the battery housing and is electrically connected to the second electrode, The cover has a mating surface that contacts the inner peripheral surface of the sidewall portion and an electrode connection portion that is electrically connected to the tab of the second electrode. The mating surface is inclined relative to the axial direction, which increases the length of the radial periphery. The cover is assembled to the battery housing via an interference fit, and thus a protrusion is provided, in which a portion of the sidewall portion of the battery housing on the open end side protrudes radially outward, and Wherein, at least a portion of the mating surface and at least a portion of the inner peripheral surface of the protrusion are engaged.

2. The battery cell according to claim 1, in, There is substantially no gap between at least a portion of the mating surface and the inner circumferential surface of the protrusion.

3. The battery cell according to claim 1, in, The gap between at least a portion of the mating surface and the inner circumferential surface of the protrusion is 10 μm or less.

4. The battery cell according to claim 1, in, The protrusion further includes an inclined portion at the end on the opening end side, wherein the length of the radial peripheral portion increases outward along the axial direction in the inclined portion.

5. The battery cell according to claim 1, in, The mating surface has a slope of 1° to 30° relative to the axial direction.

6. The battery cell according to claim 1, in, The thickness of the mating surface is greater than the thickness of the sidewall portion.

7. The battery cell according to claim 1, in, The protrusion is formed by the deformation of the sidewall portion of the battery housing on the opening end side when the cover and the battery housing are interference-fitted into each other.

8. The battery cell according to claim 1, in, The interference fit of the cap is in the range of 30 μm to 250 μm on one side.

9. The battery cell according to claim 1, in, The pressing depth of the cover into the battery housing is determined by the connection between the electrode connection portion of the cover and the tab of the second electrode of the electrode assembly housed in the battery housing.

10. The battery cell according to claim 1, in, The cover has a support surface that extends radially flat and is radially more inward than the mating surface, and The support surface is connected to the mating surface via a curved surface located at the axial inner end of the mating surface.

11. The battery cell according to claim 10, in, The electrode connection portion is located at a position that is recessed axially and further inward in the radial direction than the support surface, and The inner axial surface of the electrode connection is positioned further inward in the axial direction than the inner axial end of the curved surface.

12. The battery cell according to claim 11, in, The current collector is coupled to the tab of the second electrode for electrical connection, and The electrode connection portion is joined to the current collector to be electrically connected to the tab of the second electrode.

13. The battery cell according to claim 11, in, The electrode connection portion is directly coupled to the tab of the second electrode for electrical connection.

14. The battery cell according to claim 13, in, The junction between the electrode connection portion and the tab of the second electrode extends radially.

15. The battery cell according to claim 13, in, The electrode connection portion and the tab of the second electrode are joined by a welding portion, which is formed by a laser irradiating the surface of the electrode connection portion in a radial direction.

16. The battery cell according to claim 1, in, A liquid injection port is provided at the central part of the electrode connection.

17. The battery cell according to claim 16, in, The liquid injection port is disposed on a flat portion that protrudes outward in the axial direction from the electrode connection portion, and the flat portion is formed around the liquid injection port.

18. The battery cell according to claim 16, in, The protrusion also includes a mounting portion that is axially recessed and extends flatly in the radial direction.

19. The battery cell according to claim 1, in, The cover has a support surface that extends radially flat and is radially more inward than the mating surface. The electrode connection portion is arranged in a plurality of electrode connection portions that are radially further inward than the supporting surface, and Each of the plurality of electrode connections is recessed into the battery casing and extends radially.

20. The battery cell according to claim 19, in, The plurality of electrode connections are arranged radially around the center of the cover.

21. The battery cell according to claim 19, in, The electrode connections are arranged at equal intervals along the circumferential direction.

22. The battery cell according to claim 19, in, Three electrode connections are provided at 120° intervals.

23. The battery cell according to claim 1, in, The cover includes a vent, and The exhaust portion is positioned radially further outward than the electrode connection portion.

24. The battery cell according to claim 23, in, The cover has a support surface that extends radially flat and is radially more inward than the mating surface. The electrode connection portion is located at a position that is recessed axially and radially more inward than the support surface. The exhaust section is disposed on the support surface.

25. The battery cell according to claim 1, in, The bottom of the battery casing is provided with a first electrode terminal, which is electrically insulated from and fixed to the bottom. The first electrode of the electrode assembly is electrically connected to the first electrode terminal.

26. A battery pack comprising battery cells according to any one of claims 1 to 25.

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

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