Cylindrical battery cell, battery pack including the same, and motor vehicle

Abstract

The cylindrical battery cell includes a battery can that houses a jelly-roll type electrode assembly therein, and a cap that covers and closes the open end of the battery can. The cap is joined to the electrode tab of the electrode assembly. The cap includes two or more electrode connection portions, and each of the electrode connection portions projects axially inwardly of the battery can. The electrode connection portions are circumferentially spaced apart from each other with respect to the center of the cap, and at least two electrode connection portions are arranged to face each other with respect to the center of the cap. By having the cap function also as a current collector plate, the energy density can be increased. A manufacturing method is also disclosed, such as a battery pack including the battery cell and a vehicle equipped with the battery pack.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0068532 filed on June 3, 2022, and Korean Patent Application No. 10-2023-0026174 filed on February 27, 2023, and all the contents disclosed in the documents of the Korean patent applications are incorporated herein by reference in their entirety.

[0002] The present invention relates to a cylindrical battery cell, a manufacturing method thereof, a battery pack including the same, and a vehicle including the same.

Background Art

[0003] A cylindrical battery cell has a structure in which a jelly roll-type electrode assembly is accommodated inside a cylindrical metal can, and is more resistant to impact and temperature than a pouch-type battery. For this reason, there is an increasing demand to use can-type cells as battery cells applied to battery packs for vehicles.

[0004] However, since a can is made of metal, it may be even heavier than a pouch-type battery. For this reason, research is actively being conducted to increase the volume and internal volume of the battery can to increase the electrical capacity of the battery can.

[0005] The process of manufacturing a battery cell applying a cylindrical can includes a preparation step of deep drawing a metal sheet to form a circular bottom and a circular tubular side wall portion connected thereto, and hermetically fixing a first electrode terminal to the center of the circular bottom of the can. The above process further includes a step of preparing a jelly roll-type electrode assembly having a first current collector plate and a second current collector plate at both axial ends. The above process also includes an assembly step of accommodating the electrode assembly in the can, connecting the first current collector plate to the first electrode terminal, connecting the second current collector plate to the can or the cap, filling the inside of the can with an electrolyte, and covering the open end of the side wall portion with a cap to finish.

[0006] The cylindrical battery cell manufactured as described above must provide a space for accommodating the second current collector plate inside the can. Therefore, the volume of the electrode assembly has to be reduced accordingly, resulting in a lower energy density. Also, the traditional manufacturing process of a cylindrical battery cell requires an additional step of manufacturing the second current collector plate and connecting it to the second electrode of the electrode assembly, which causes an increase in the manufacturing cost per unit of the battery cell.

Summary of the Invention

Problems to be Solved by the Invention

[0007] The present invention was devised to solve the above-described problems. When connecting the electrode assembly to the electrode terminal of the can, the present invention aims to provide a battery cell that can provide the reliability of electrical connection between the electrode of the electrode assembly and the electrode terminal of the can, despite omitting the current collector plate.

[0008] The present invention aims to provide a battery cell that has fewer components and manufacturing steps, is simpler, and can reduce the manufacturing cost per unit.

[0009] The present invention aims to provide a battery cell with a high energy density, which is advantageous for being mounted on a vehicle, as well as a battery pack and an automobile including the same.

Means for Solving the Problems

[0010] One aspect of the present invention provides a battery cell. The battery cell may preferably include a battery can, an electrode assembly, and a cap. The battery cell preferably includes a side wall portion that extends axially between a closed end portion and an open end portion on the opposite side, and the open end portion provides an opening to the internal space of the battery can. The electrode assembly preferably includes two electrodes housed inside the battery can, and at least one tab extending from the second electrode among the two electrodes may be disposed near the open end portion of the battery can. The cap may preferably be disposed to close the open end portion of the battery can by covering the opening. The cap may preferably include a plurality of electrode connection portions that project axially into the battery can so as to make direct electrical contact with at least one tab of the second electrode. The electrode connection portions are preferably arranged circumferentially spaced apart from each other with respect to the center of the cap, and preferably, at least two electrode connection portions may be arranged on opposite sides of each other with respect to the center of the cap.

[0011] According to at least some aspects of the present invention, the electrode connection portion and the tab (etc.) of the second electrode may be connected by a welded portion.

[0012] According to at least some aspects of the present invention, the at least one tab may include a plurality of tabs extending in a radial direction perpendicular to the axial direction so as to be at least partially overlapped with each other along the axial direction.

[0013] According to at least some aspects of the present invention, each electrode connection portion may extend along the radial direction of the cap.

[0014] According to at least some aspects of the present invention, four electrode connection portions may be arranged at equal intervals in the circumferential direction. According to at least some aspects of the present invention, each electrode connection portion may linearly extend along each radial direction.

[0015] According to at least some aspects of the present invention, the electrode connection portions may be connected to each other by a protrusion of the cap in the central region in the radial direction of the cap, and the protrusion may protrude axially into the interior of the battery can.

[0016] According to at least some aspects of the present invention, the electrode connection portions may be connected to each other by a protrusion extending along the periphery of the outer region in the radial direction of the cap, and the protrusion may protrude axially into the interior of the battery can.

[0017] According to at least some aspects of the present invention, the cap may include an electrically conductive material that is electrically connected to the side wall portion at the open end of the battery can along the outer edge in the radial direction of the cap. The electrode connection portions may be integrally formed with the electrically conductive material of the cap. In some examples, each electrode connection portion can correspond to each recess formed on the outer surface of the cap that extends axially away from the interior of the battery can.

[0018] According to at least some aspects of the present invention, the cap may include a liquid injection port provided in the central portion of the cap. These liquid injection ports may be located in the central protruding region of the cap, and the central protruding region may be arranged axially further away from the interior of the battery can than each contact surface of each of the electrode connection portions. The contact surface may be in direct electrical contact with the tab (etc.) of the second electrode.

[0019] According to some aspects of the present invention, an intermediate region can be defined between axially spaced electrode connection portions. These intermediate regions may be arranged further axially away from the interior of the battery can than the contact surfaces of the electrode connection portions. In some of these aspects of the present invention, the central protruding region of the cap may be radially spaced from the intermediate region by an outer surface portion of the cap that is axially closer to the interior of the battery can than the central protruding region and the intermediate region. In other of these aspects of the present invention, the central protruding region of the cap may be directly adjacent to the intermediate region in the radial direction.

[0020] According to some aspects of the present invention, the cap may include a vent. These vents may be located radially outside the electrode connection portions.

[0021] According to some aspects of the present invention, the first electrode terminal is located along the closed end of the battery can. These electrode terminals may be electrically insulated from the closed end of the battery can. Also, the first electrode of the electrode assembly may be electrically connected to the first electrode terminal via a first current connection plate located axially between the electrode assembly and the closed end of the battery can.

[0022] According to some aspects of the present invention, the cap may be configured and arranged such that the outermost surface of the cap that is axially farthest from the interior of the battery can is axially farther away from the interior of the battery can than the open end of the battery can.

[0023] According to some aspects of the present invention, the electrode connection portions may be located on opposite sides of the center of the cap such that the straight line connecting them extends through the center of the cap.

[0024] According to some aspects of the present invention, the electrode connection portions may extend along the radial direction. Also, in some of these aspects, the electrode connection portions may linearly extend along a straight line extending through the center of the cap.

[0025] Another aspect of the present invention provides a method for manufacturing a battery cell as described above. These methods preferably include assembling the battery cell, after assembling the battery cell, joining the electrode connection part to at least one tab of the second electrode, joining the cap to the battery can, and injecting an electrolytic solution into the battery can. Assembling the battery cell preferably includes positioning the electrode assembly inside the battery can and positioning a cap to cover the opening of the open end of the battery can in order to close the open end of the battery can.

[0026] According to at least some aspects of the above invention, injecting the electrolytic solution into the battery can can be performed through a liquid injection port in the central portion of the cap. Some of these aspects may further include covering the liquid injection port with a stopper.

[0027] According to at least some aspects of the above invention, joining the plurality of electrode connection parts to at least one tab of the second electrode can be performed by irradiating a laser on the outer surface of the cap in a direction away from the inside of the battery can in the axial direction.

[0028] Another aspect of the present invention provides a battery pack including a battery cell as described above, and a vehicle including these battery packs.

Advantages of the Invention

[0029] According to some embodiments of the present invention, since the cap is fixed while being electrically directly connected to the tab of the second electrode and the cap is fixed while being electrically connected to the side wall portion of the can, a current collector plate can be omitted. Therefore, the energy density of the battery cell can be increased, the number of parts of the battery cell can be reduced, and the manufacturing process can be simplified. As a result, the manufacturing cost per unit of the battery cell can be reduced.

[0030] According to some embodiments of the present invention, since the electrode connection part of the cap connected to one or more tabs of the second electrode extends along the radial direction, the cap is electrically directly connected from the core part to the outer peripheral part of the second electrode, and the internal resistance can be greatly reduced.

[0031] According to some embodiments of the present invention, the cap is provided with a plurality of electrode connection parts extending in the radial direction, and each electrode connection part is recessed inward in the axial direction so as to protrude toward the inside of the battery can in the axial direction and protrude toward the tab of the second electrode. Therefore, the adhesion between each electrode connection part and the tab of the second electrode can be ensured, and thereby the joining quality between them can be ensured.

[0032] Also, these shapes greatly improve the torsional resistance of the cap. In addition, it can cause an increase in the connection strength between the peripheral part of the cap and the open end of the battery can. Therefore, the joining quality of the battery can and the cap can also be greatly improved.

[0033] According to some embodiments of the present invention, the electrode connection parts of the cap are radially arranged, arranged at equal intervals in the circumferential direction, and the torsional resistance can be uniformly ensured along the circumferential direction, and the current path can be uniformly distributed.

[0034] According to some embodiments of the present invention, a pair of electrode connection parts facing each other across the center of the cap are aligned in a row, and the shape of the jig for pressing the cap into the battery can or making it adhere to the electrode assembly can be simply realized, and the locus of the welding line can be simplified.

[0035] According to some embodiments of the present invention, four electrode connection parts are arranged at 90-degree intervals to increase the torsional resistance of the cap, simplify the welding process, and increase the joining strength between the tab of the second electrode and the plurality of electrode connection parts. In addition, the plastic working part of the cap can be suppressed, and the reduction of the rigidity of the cap can be suppressed.

[0036] According to some embodiments of the present invention, the centrifugal side edges of the plurality of electrode connection parts can be in contact with the inner peripheral surface of the battery can, and a press-fitting connection can be provided to guide the central alignment of the cap with respect to the battery can. In the process of pressing the can into the battery can, the center of the cap can be naturally aligned with the battery can.

[0037] According to some embodiments of the present invention, the press-in depth of the cap may be regulated by the electrode connection part, so that the adhesion between the electrode connection part and the tab (etc.) of the second electrode is ensured sufficiently, and these joints may be made.

[0038] According to the present invention, since the outermost surface of the cap, which is located further axially outside than the joint part between the cap and the battery can, is arranged between two circumferentially adjacent electrode connection parts, the joint part can be protected.

[0039] Then, when the battery can is placed correctly, that is, when the outermost surface is placed on the floor, the outermost surface will support the load of the battery cell. At this time, the outermost surfaces located on both sides in the circumferential direction of the electrode connection part exert an effect of pressing the electrode connection part toward the tab of the second electrode. Therefore, the phenomenon that the joint part between the cap and the tab of the second electrode is damaged due to vibration or impact can be minimized.

[0040] The liquid injection port provided in the central part of the cap can diversify the manufacturing process of the battery cell. Further, since the liquid injection port protrudes more than the electrode connection part, the phenomenon that the welding heat or joining heat generated when the liquid injection port is plugged with a plug is transmitted to the electrode assembly can be minimized.

[0041] When the vent provided in the cap is provided radially outside the electrode connection part or the welding part, a wider area of the cap where the pressure resistance of the battery can acts can be ensured, the vent action can occur more easily, and when the vent part is damaged by the vent, the electrical connection between the second electrode and the battery can can be interrupted.

[0042] The above object, other objects, features, and advantages of the present invention will become apparent to those skilled in the art from the following detailed description of the embodiments of the invention with reference to the drawings described below.

Brief Description of the Drawings

[0043]

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Mode for Carrying Out the Invention

[0044] The above-mentioned objects, features and advantages will be described in detail later with reference to the accompanying drawings. In the description of the present invention, when it is determined that a specific description of the known technology related to the present invention will obscure the gist of the present invention, the detailed description will be omitted. The same reference numerals in the drawings are used to indicate the same or similar components.

[0045] Although terms such as first, second, etc. are used to describe various components, these components are of course not limited by these terms. These terms are merely used to distinguish one component from another, and of course, unless otherwise stated, the first component may be the second component.

[0046] Throughout the specification, unless otherwise stated, each component may be singular or plural. Also, unless otherwise stated, a singular expression may include plural expressions.

[0047] Hereinafter, when it is stated that any configuration is arranged "above (or below)" a component or "on (or under)" a component, it means that not only is any configuration arranged in contact with the upper surface (or lower surface) of the said component, but other configurations may also be interposed between the said component and any configuration arranged "above (or below)" the said component.

[0048] Also, when a component is described as being "connected", "coupled" or "joined" to another component, it should be understood that the components may be directly connected or joined to each other, but other components may be "interposed" between the components, or the components may be "connected", "coupled" or "joined" through other components.

[0049] The singular expressions used in this specification include plural expressions unless the context clearly indicates otherwise. Terms such as "configured" or "comprising" in this application should not be construed as necessarily including all of the multiple components or multiple steps described in the specification. Some of the components or steps may not be included, or additional components or steps may be included.

[0050] In the entire specification, when it is "A and / or B", this means A, B, or A and B, unless otherwise stated. When it is "C to D", this means C or more and D or less, unless otherwise stated.

[0051] In the description of the embodiments, the axial direction refers to the direction in which the axis forming the winding center of the jelly roll type electrode assembly extends. The radial direction refers to the direction of approaching (centripetal) or moving away (centrifugal) from the axis. The circumferential direction refers to the direction surrounding the axis as the outer circumference of a circle.

[0052] The width direction in the unfolded state of the electrode assembly corresponds to the axial direction of the jelly roll. The length direction in the unfolded state of the electrode assembly corresponds to the circumferential direction of the jelly roll.

[0053] Hereinafter, with reference to FIGS. 1 to 8, the structure of the cylindrical battery cell of the embodiment according to the present invention will be described.

[0054] The battery cell of the embodiment may be, for example, a cylindrical battery cell in which the form factor ratio (the value obtained by dividing the diameter of the cylindrical battery cell by the height, that is, the ratio of the diameter (Φ) to the height (H)) is greater than approximately 0.4.

[0055] Here, the form factor means a value indicating the diameter and height of the cylindrical battery cell. The cylindrical battery cell applied to the pressure tester may be, for example, a 46110 cell, a 48750 cell, a 48110 cell, a 48800 cell, or a 46800 cell. In the numerical value indicating the form factor, the first two digits indicate the diameter of the cell in mm, the next two digits indicate the height of the cell in mm, and the last digit of 0 indicates that the cross-section of the cell is circular.

[0056] The battery cell applied to the pressure tester may be a substantially cylindrical cell with a diameter of approximately 46 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0057] A battery cell according to another embodiment may be a substantially cylindrical cell having a diameter of approximately 48 mm, a height of approximately 75 mm, and a form factor ratio of 0.640.

[0058] A battery cell according to yet another embodiment may be a substantially cylindrical cell having a diameter of approximately 48 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0059] A battery cell according to yet another embodiment may be a substantially cylindrical cell having a diameter of approximately 48 mm, a height of approximately 80 mm, and a form factor ratio of 0.600.

[0060] A battery cell according to yet another embodiment may be a substantially cylindrical cell having a diameter of approximately 46 mm, a height of approximately 80 mm, and a form factor ratio of 0.575.

[0061] The pressure tester of the present invention can of course be applied to battery cells having a form factor ratio of approximately 0.4 or less, such as 18650 cells, 21700 cells, etc. In the case of 18650 cells, the diameter is approximately 18 mm, the height is approximately 65 mm, and the form factor ratio is 0.277. In the case of 21700 cells, the diameter is approximately 21 mm, the height is approximately 70 mm, and the form factor ratio is 0.300.

[0062] The battery can 10 includes a cylindrical side wall portion 11 extending in the axial direction between a closed first end portion and an open second end portion, and a bottom portion 12 connected to one axial end portion of the side wall portion 11.

[0063] A hole may be formed in the central portion of the bottom 12, and the first electrode terminal 13 may be inserted and coupled to the hole. The first electrode terminal 13 can be riveted and fixed to the bottom 12 with the terminal gasket 14 interposed therebetween. The terminal gasket 14 is interposed between the first electrode terminal 13 and the bottom 12 to seal the inside and outside of the battery can 10, prevent leakage of the electrolyte, and electrically insulate the first electrode terminal 13 and the bottom 12.

[0064] However, the connection method between the first electrode terminal 13 and the bottom 12 is not limited thereto. For example, any structure that can seal between the first electrode terminal 13 and the bottom 12 and electrically insulate the first electrode terminal 13 and the bottom 12 can adopt various other fixing methods, such as bolt-nut connection method, glass seal method, or PP-MAH thermal bonding method, etc.

[0065] The first electrode terminal 13 has a first polarity, and the battery can 10 can have a second polarity. Accordingly, both the bottom 12 of the battery can 10 and the side wall portion 11 connected thereto can have the second polarity. Thus, the bottom 12 surrounding the first electrode terminal 13 can constitute the second electrode terminal 15, and the side wall portion 11 connected to the bottom 12 and the second electrode terminal can be formed.

[0066] Then, both the first electrode terminal 13 and the second electrode terminal 15 may be disposed at one axial end of the battery can 10. Then, the bus bar connected to the first electrode terminal 13 and the bus bar connected to the second electrode terminal 15 may both be located at one axial end of the battery can 10, that is, the upper part.

[0067] In one example, the first electrode terminal 13 may be a positive electrode terminal, and the second electrode terminal 15 may be a negative electrode terminal. Of course, the reverse may also be true.

[0068] The electrode assembly 20 is accommodated inside the battery can 10. As shown in FIG. 2, the electrode assembly 20 has a predetermined width and includes a first electrode 21, a second electrode 22, and a separator 28 extending in the length direction. As shown in FIGS. 3 and 4, after forming a laminate in which the first electrode 21, the separator 28, the second electrode 22, and the separator 28 are laminated in this order, it is manufactured in a jelly roll shape wound around a winding core shaft.

[0069] The first electrode 21 may be a positive electrode, and the second electrode 22 may be a negative electrode. Of course, the reverse may also be true.

[0070] The first electrode 21 and the second electrode 22 are manufactured in a sheet shape. The electrode sheet is manufactured in a form in which an active material layer 24 is coated on the surface of a metal foil 23. The electrode sheet includes a grounded portion 25 region where the active material layer 24 is coated and an ungrounded portion 26 region where the active material layer 24 is not coated. The positive electrode sheet has an ungrounded portion 26 region on one side in the width direction, and the negative electrode sheet has an ungrounded portion 26 region on the other side in the width direction.

[0071] The ungrounded portion 26 region is exposed or protrudes in the width direction in the laminate. The ungrounded portion 26 itself functions as an electrode tab. Here, although the electrode "tab" refers to an integrated portion of the metal foil 23 protruding outward from the electrode assembly 20, these "tabs" may be separately manufactured and have an electrically conductive configuration that is firmly electrically connected to the current collecting metal foil 23 of the electrode.

[0072] Notches can be formed in the ungrounded portion 26 at predetermined intervals to form flag-shaped notch tabs 27.

[0073] In the embodiment, it is exemplified that the notch tab 27 is an equilateral trapezoid. However, these forms may be various forms such as a semi-circular shape, an anti-elliptical shape, a triangular shape, a rectangular shape, and a parallelogram shape.

[0074] In addition, in the embodiment, an example is illustrated in which the notch tabs 27 arranged along the length direction have the same width. However, the width of the notch tabs may be gradually or stepwise widened from the core side to the outer peripheral side.

[0075] In addition, in the embodiment, an example is illustrated in which the height of the notch tab 27 gradually increases from the core side to the outer peripheral side. However, the height of these notch tabs may be constant or embodied in a form that gradually decreases.

[0076] In the jelly roll type electrode assembly 20, the notch tab 27 may be bent inward or outward in the radial direction. In the embodiment, as shown in FIGS. 5 and 6, a structure in which the notch tab 27 is bent inward in the radial direction is illustrated.

[0077] The notch tab 27 can be bent one by one in the process of winding up the laminate to form the jelly roll type electrode assembly 20. Different from this, the notch tab 27 can also be bent at once after winding up the laminate to form the jelly roll type electrode assembly.

[0078] In this way, the notch tabs 27 of the first electrode 21 and the notch tabs 27 of the second electrode 22 that overlap while being bent in the radial direction can provide planes that are substantially perpendicular to the axial direction at both axial ends of the electrode assembly 20, as shown in FIG. 6.

[0079] A current collector plate 31 may be joined to the substantially flat surface provided by bending the notch tabs 27 exposed at both axial ends of the electrode assembly 20, as shown in FIG. 7.

[0080] The current collector plate 31 can be manufactured by punching, trimming, piercing, or bending a metal sheet.

[0081] Referring to FIG. 7, the current collector plate 31 includes one or more terminal connection portions 32 extending radially from the central portion, a ring portion 33 connecting the centrifugal side edges of the terminal connection portions 32 in the circumferential direction, and an electrode connection portion 34 extending from the ring portion 33 toward the centripetal side but not connected to the terminal connection portion 32. The central portion of the terminal connection portion 32 covers at least a part of the core hollow portion of the electrode assembly 20.

[0082] Before the electrode assembly 20 is placed in the battery can 10, the electrode connection portion 34 is joined to the notch tab 27 of the first electrode 21 of the electrode assembly 20 by a method such as laser welding.

[0083] Referring to FIG. 8, a current collector plate may not be connected to the notch tab 27 of the second electrode 22 of the electrode assembly 20.

[0084] As shown in FIGS. 9 and 10, the electrode assembly 20 is housed in the battery can 10 in a state where the current collector plate 31 is aligned so as to face the bottom 12 of the battery can 10. At this time, an insulator 19 is interposed between the current collector plate 31 and the bottom 12 of the battery can 10 to electrically insulate the current collector plate 31 and the bottom 12.

[0085] Then, the terminal connection portion 32 of the current collector plate 31 is joined to the first electrode terminal 13 by a method such as resistance welding, ultrasonic welding, or laser welding. For welding the current collector plate 31 and the first electrode terminal 13, the welding device 100 can approach the back surface of the center of the terminal connection portion 32 of the current collector plate 31 axially through the core hollow portion of the electrode assembly 20 to perform welding. Of course, it goes without saying that the current collector plate 31 and the first electrode terminal 13 can also be joined by brazing or soldering methods.

[0086] Referring to FIGS. 11 and 12, the notch tab 27 of the second electrode 22 may be directly connected to a cap 40 that covers an opening defined by the open end of the battery can 10. The second electrode 22 is electrically connected via a welded portion (W) of the notch tab 27 and the cap 40. Of course, the notch tab 27 and the cap 40 may also be joined by a method such as brazing or soldering.

[0087] The cap 40 is made of an electrically conductive material. Also, the cap 40 can be integrally made of these materials. The edge of the cap 40 is joined to the side wall portion 11 of the battery can 10 to be electrically connected and sealed and fixed. Thereby, the second electrode 22 may be electrically connected to the cap 40 and the battery can 10. Various methods such as welding, brazing, and soldering can be applied to join the cap 40 and the battery can 10 so that they can be electrically connected and sealed.

[0088] The cap 40 and its assembly process shown in FIGS. 11 and 12 are illustrated as an example, and various embodiments of the structure of the cap 40 and the assembly method thereby will be described below. In the embodiments described later, although it is exemplified that these joint portions are joined by welding, it is of course understood that the present invention is not limited thereto.

[0089] [First Embodiment] Hereinafter, with reference to FIGS. 13 to 18, a first embodiment of the cap and the structure of a battery cell to which this is applied will be described.

[0090] The cap 40 can be made from a circular metal sheet. The cap 40 includes one or more electrode connection portions 41 that are recessed in a direction corresponding to the axial direction of the battery cell 72. The electrode connection portions 41 can be formed by stamping, such as pressing the metal sheet with a press and a die of one or more shapes. Thus, by these stampings, each protrusion defined by the electrode connection portion 41 on the lower side of the cap 40 can correspond to each recessed portion on the upper side of the cap.

[0091] The bottom surface of the electrode connection portion 41 defines a contact surface that is in close contact and joined to the notch tab 27 of the second electrode 22 of the electrode assembly 20, respectively. The electrode connection portion 41 manufactured by pressing the metal sheet will have a thickness slightly thinner than the thickness of the metal sheet. Thus, when a laser (L) is irradiated on the surface of the electrode connection portion 41, the local heat generated by the laser can melt and join the surface of the electrode connection portion 41 and the surface of the notch tab 27 in contact with the contact surface at the bottom of the electrode connection portion 41.

[0092] The electrode connection portions 41 are provided as a plurality of protrusions that project downward in the axial direction toward the inside of the battery can 10. In the embodiments of FIGS. 13 to 18, four electrode connection portions 41 linearly extend along each radial direction to be formed radially. These electrode connection portions 41 are preferably arranged at equal intervals in the circumferential direction with respect to the center 46 of the cap 40. In the case of these four electrode connection portions 41, they may be spaced apart at 90-degree intervals. Also, the electrode connection portions 41 are joined to each other in the central region in the radial direction of the cap 40, and the central region of the cap 40 can also form protrusions that project downward into the inside of the battery can 11 in the axial direction. These central protrusions may be continuously formed at the same depth as the electrode connection portions 41. Thus, when there are four electrode connection portions 41 at equal intervals, these electrode connection portions and the central protrusions connecting them combine to form a cross shape as shown in FIGS. 13 to 15.

[0093] The welding part (W) for joining the one or more electrode connection parts 41 to the notch tab 27 of the second electrode 22 of the electrode assembly 20 may have a linear shape formed in the radial direction so as to correspond to the extending direction of the electrode connection part 41.

[0094] According to the embodiment, the welding part (W) having a shape extending linearly and aligned in the radial direction is formed for each of the plurality of electrode connection parts 41.

[0095] The cap 40 provides an outermost surface 44 which is a surface in contact with the ground when the battery can 10 is stood upright such that the cap 40 of the battery can 10 faces the ground. Each outermost surface 44 is provided at a position further raised than the electrode connection part 41 (for example, so as to be farther from the inside of the battery can 10 in the axial direction) and is disposed between two circumferentially adjacent electrode connection parts 41.

[0096] Thereby, with the outermost surface 44 being axially pressed by a jig and the electrode connection part 41 and the notch tab 27 being in close contact, a laser is irradiated onto the surface of the electrode connection part 41 to weld the electrode connection part 41 and the notch tab 27. Then, on both opposite sides of the weld line, since the pressure of the jig presses the electrode connection part 41 against the notch tab 27 in close contact, welding can be surely performed.

[0097] A pair of electrode connection parts 41 facing each other with respect to the center 46 of the cap 40 has a form of being disposed on a straight line passing through the center 46 of the cap 40. Thereby, when forming the weld line, the weld lines of the two electrode connection parts 41 aligned in a row with each other can be formed by only one movement of the laser welder. For example, when the first electrode connection part, the second electrode connection part, the third electrode connection part, and the fourth electrode connection part are sequentially arranged along the circumferential direction in the cap 40 of the first embodiment, the first electrode connection part and the third electrode connection part may be welded at once, and the second electrode connection part and the fourth electrode connection part may be welded at once.

[0098] Also, according to the embodiment, even when the outermost surface 44 between the first electrode connection part and the third electrode connection part is pressed with a jig, due to the large secondary moment of inertia formed by the recessed shapes of the second electrode connection part and the fourth electrode connection part, the cap 40 can move as a rigid body without being twisted or bent despite the pressure of the jig. In fact, it is believed that the strength and rigidity of the cap 40 can be increased particularly efficiently without adding material and weight by having at least two electrode connection parts 41 located on opposite side surfaces of the center 46 of the cap 40 with respect to each other. In this regard, without being limited to a specific operating theory, arranging these electrode connection parts 41 along a straight line extending through the center 46 of the cap, particularly when these electrode connection parts extend along that line (and when extending from the central region of the cap 40 to the opposite side surfaces), these arrangements would define part of a cap structure similar to a reinforcing beam extending across the cap. Also, having four electrode connection parts 41 arranged at equal intervals about the center 46 and extending along two straight lines perpendicular to each other is considered to further strengthen the cap in a manner similar to a vertical beam having a moment resistance connection therebetween.

[0099] In the embodiment, as described above, by forming the four electrode connection parts 41, all four electrode connection parts 41 can be welded with two laser scan trajectories.

[0100] If the number of the electrode connection parts 41 is processed too much, the strength of the cap 40 made of a metal sheet may become weak. Also, if only two or three electrode connection parts 41 are formed, it is difficult to form a cross-section for sufficiently ensuring the secondary moment of inertia along the circumferential direction.

[0101] As in the embodiment, when four electrode connection portions 41 are formed in a cross shape or a "+" shape on the cap 40, the welding process can be performed accurately and simply, and the torsional resistance and bending resistance of the cap 40 can also be improved, and it is possible to reduce or prevent the strength of the cap 40 from being weakened by the forming process. Further, the cap 40 can not only provide the function of a current collector plate, but also maintain the strength for its original function of closing the open end of the battery can 10.

[0102] The outer edge in the radial direction of the cap 40 has a shape that can be joined to the axial end of the side wall portion 11 at the open end of the battery can 10. For this reason, the electrode connection portion 41 may be formed at a distance radially inward from the outer edge of the cap, whereby the bottom surface of the outer edge in the radial direction of the cap 40 defines a joining surface 47 having a profile that extends circularly about the center 46 of the cap 40. The joining surface 47 of the cap 40 contacts the axial end surface of the side wall portion 11 at the open end of the battery can 10 as shown in FIG. 18, and these contact surfaces can be welded by a laser that irradiates radially inward along the outer circumference of the battery can 10 to form a joint portion (M).

[0103] The outer edge in the radial direction of the electrode connection portion 41 can define a press-fitting outer wall 45 having an outer diameter corresponding to the inner diameter of the battery can 10. Therefore, when the cap 40 is assembled to the battery can 10, the press-fitting outer walls 45 of the plurality of electrode connection portions 41 slide and press against the inner circumferential surface of the battery can 10 respectively, and guide the centering of the cap 40 with respect to the battery can 10.

[0104] According to the first embodiment, the four press-fitting outer walls 45 are evenly arranged along the circumferential direction and slide with the battery can 10 in a part of the entire circumference of the inner circumferential surface. Therefore, the cap 40 can be relatively easily pressed into the battery can 10.

[0105] Thus, the cap 40 of the embodiment has the advantage that the assembly is easy because the press-fitting outer wall 45 is formed together when the electrode connection portion 41 is formed.

[0106] Furthermore, according to the structure of the cap 40 of the embodiment, since the lasers for welding the cap 40 and the battery can 10 are irradiated in a radially aligned manner, even if the joint surface 47 of the cap 40 fails to be in close contact with the axial end portion of the side wall portion 11 in one or more regions due to an unexpected error, the lasers will not be aligned to damage the electrode assembly 20 inside the battery can 10.

[0107] According to the first embodiment, since the outermost surface 44 of the cap 40 is axially further outside than the joint portion (M) between the cap 40 and the battery can 10, the battery can 10 in FIG. 18 can be turned over and properly stood up. Therefore, the joint portion (M) does not directly contact the ground, and it is easy to protect the joint portion (M).

[0108] When the above-described cap 40 is applied, it is not necessary to use a current collector plate to electrically connect the tab of the second electrode 22 to the battery can 10. Therefore, the number of parts and the assembly man-hours can be reduced, the internal volume can be further secured, and the energy density can be increased. Although the cap 40 electrically connected to the battery can 10 is directly connected to the metal foil 23 of the second electrode of the electrode assembly 20, since it is connected via a welding portion (W) that extends long in the radial direction, the current path is preferably uniformly distributed, and the internal resistance can also be greatly reduced.

[0109] [Second Embodiment] Hereinafter, with reference to FIGS. 19 to 24, a second embodiment of the cap and the structure of a battery cell to which this is applied will be described. When describing the second embodiment, the content overlapping with the above-described first embodiment can be omitted. Therefore, the portions not described in any of the embodiments can be understood from the other embodiments. Furthermore, it can be easily understood that the configuration of any one of the embodiments and the configuration of the other embodiments can be replaced with each other, added, or omitted.

[0110] The cap of the second embodiment is different from the cap of the first embodiment in that a protruding portion in the shape of an annular protrusion 48 extends along the radially outer edge region of the cap 40, and the annular protrusion 48 protrudes downward axially into the interior of the battery can 10. The annular protrusion 48 connects various electrode connection portions 41. The radially outer edge of the cap 40 is defined by the radially outer edge of the annular protrusion 48, and this outer edge is configured to be located within the inner diameter of the side wall 11. Thus, the radially outer edge constitutes a press-fitting outer wall 45.

[0111] The annular protrusion 48 may be formed together when one or more electrode connection portions 41 are formed. The outermost surface 44 of the cap 40 may be disposed on an intermediate region 49 of the cap 41 defined between circumferentially spaced-apart electrode connection portions 41 inside the annular protrusion 48 in the radial direction, and the cap 40 may have a configuration in which the bottom of the annular protrusion 48 is connected to the bottom of the electrode connection portion 41. That is, the outermost surface 44 is disposed on the intermediate region 49 of the cap 40 between the electrode connection portions 41 in the circumferential direction and inside the annular protrusion 48 in the radial direction.

[0112] Unlike the first embodiment, the cap 40 of the second embodiment can be pressed into the battery can 10 with the outer peripheral surface of the press-fitting outer wall 45 in contact with the inner peripheral surface of the battery can 10 as shown in FIG. 24. The press-fitting outer wall 45 does not regulate the press-fitting depth of the axially pressed cap 40. The press-fitting depth of the cap 40 in the second embodiment can be regulated by the electrode connection portion 41. That is, the cap 40 can be pressed until the bottom surface of the electrode connection portion 41 is in close contact with the notch tab 27 of the electrode assembly 20.

[0113] In such a state, the electrode connection portion 41 and the notch tab 27 are welded in the length direction of the electrode connection portion, that is, in the radial direction, to form a welded portion (W), and the upper end portion of the outer peripheral surface of the press-fitting outer wall 45 and the upper end portion of the side wall portion 11 of the battery can 10 are welded to form a joint portion (M).

[0114] The outermost surface 44 is located further axially outward than the axial end 39 of the press-fitting outer wall 45. That is, the height of the outermost surface 44 is higher than the height of the press-fitting outer wall 45. Therefore, even when the battery can 10 is stood up such that the cap 40 contacts the ground with the joint (M) formed between the press-fitting outer wall 45 and the side wall portion 11, the joint (M) does not directly receive a load from the ground and the joint (M) can be protected.

[0115] Further, when the outermost surface 44 contacts the ground and receives a load, these loads act axially to crimp the electrode connection portion 41 and the tab of the second electrode 22 to each other, so that the welded portion (W) of the cap 40 and the notch tab 27 is also protected.

[0116] The cap 40 of the second embodiment has a cross-section with a high second moment of inertia along the circumferential direction of the edge, so that the torsional resistance and bending resistance are even higher.

[0117] [Third Embodiment] Hereinafter, with reference to FIGS. 25 to 30, a third embodiment of the cap and the structure of a battery cell to which this is applied will be described.

[0118] Compared with the first embodiment, the cap 40 of the third embodiment further includes a liquid injection port 42 at the central portion of the cap 40. The liquid injection port 42 can be aligned with the hollow portion of the winding core of the electrode assembly 20.

[0119] The liquid injection port 42 can be provided on the central protruding region of the cap 40 such as a circular protruding portion 43 that protrudes slightly above the electrode connection portion 41 of the cap 40. The height of the protruding portion 43 is set lower than the height of the outermost surface 44. The height of the plug 50 may also be lower than the height of the outermost surface 44 in a state where the liquid injection port 42 is covered and closed by a plug 50 to be described later.

[0120] Since the protruding portion 43 protrudes higher than the bottom of the cap 40, when the electrolyte is injected through the liquid injection port 42 and then the plug 50 is covered and joined by a method such as welding, preferably, the heat for joining is not transmitted to the electrode assembly 20, reducing the risk of damaging the separator membrane.

[0121] The caps 40 of the first and second embodiments described above do not have a separate liquid injection port. Therefore, when the cap 40 is placed on the battery can 10 during the production of these embodiments, since the battery can 10 does not have a separate liquid injection port, the electrolyte injection process is performed first before covering the battery can 10 with the cap 40.

[0122] However, when the liquid injection port 42 is provided in the cap 40 as in the third embodiment, after the cap 40 is assembled on the battery can 10 to form the welded portion (W) and the joined portion (M), the electrolyte can be injected through the liquid injection port 42. Then, compared to joining the cap 40 to the battery can 10 that has already been filled with the electrolyte, the third embodiment having the liquid injection port 42 has the advantage of reducing the influence of the joining heat on the electrolyte. Furthermore, even when joining around the plug 50 and the liquid injection port 42, since the protruding portion 43 protrudes upward so as to be far from the inside of the battery can, the possibility that the joining heat of the plug 50 affects the electrolyte can also be reduced.

[0123] Since the plug 50 is also located lower than the outermost surface 44, even when the battery cell is stood with the cap 40 in contact with the ground, the plug 50 does not receive direct load.

[0124] On the other hand, the liquid injection port 42 formed in the center of the cap 40 can be a passage through which the configuration of the equipment can enter and exit for welding the first electrode terminal 13 and the current collector plate 31 of the first electrode 21. As a result, as shown in FIG. 30, the cap 40 may first be joined to the tab of the second electrode 22 of the electrode assembly 20 and then housed in the battery can 10.

[0125] That is, as shown in FIG. 30, the electrode assembly 20 can be housed in the battery can 10 in a state where the current collector plate 31 is joined to the tab of the first electrode 21 of the electrode assembly 20 and the cap 40 is joined to the tab of the second electrode 22. Then, the welding operation between the current collector plate 31 and the first electrode terminal 13 can be performed through the liquid injection port 42 of the cap 40 and the winding core hollow portion of the electrode assembly 20.

[0126] [Fourth Embodiment] Hereinafter, with reference to FIGS. 31 to 35, a fourth embodiment of the cap and the structure of the battery cell to which this is applied will be described.

[0127] Similar to the relationship between the third embodiment and the first embodiment, the cap 40 of the fourth embodiment also further includes a liquid injection port 42 at the central portion compared to the second embodiment. And, the cap of the fourth embodiment has a form in which the inner side in the radial direction of the intermediate region 49 of the cap 40 is separated from the protruding portion 43 to the outer side in the radial direction by the annular portion 55 of the cap 40 with respect to the second embodiment. As a result, both the inner side and the outer side in the radial direction of the intermediate region 49 can have an arc shape.

[0128] A vent 60 having a form of a weak or thin portion is provided along the bottom of the annular protrusion 48 of the cap 40. The vent 60 can be provided by forming notches on both sides or one side of the upper surface and the bottom surface of the annular protrusion 48. The vent 60 is provided outside the electrode connection portion 41 in the radial direction and may extend along the circumferential direction.

[0129] Preferably, the vent 60 has a strength that does not deform under the force applied when the cap 40 is pushed into the battery can 10. On the other hand, when the internal pressure suddenly increases due to a short circuit or the like occurring inside the battery can 10, the vent 60 is damaged, and the electrode connection portion 41 of the cap 40 can be separated from the push-in outer wall 45 of the cap 40. As a result, the electrical connection between the electrode connection portion 41 connected to the tab of the second electrode 22 and the battery can 10 is broken, the internal space of the battery can 10 is opened to the outside, and the gas causing the pressure resistance is discharged.

[0130] Further, the vent 60 is provided radially outside the intermediate region 49 of the cap 40 provided with the outermost surface 44. And, as described above, these outermost surfaces 44 are disposed on the intermediate region 49 of the cap 40 provided between the electrode connection portions 41 in the circumferential direction.

[0131] Therefore, when the pressure resistance of the battery can 10 increases, these pressures act on the bottom surface of the cap 40 and forcibly push up the portion of the cap 40 located radially inside the vent 60. The action of these forces occurs concentratedly in four regions located in the circumferential direction (for example, on the bottom surface of the intermediate region 49 provided between the circumferential directions of the electrode connection portions 41). Therefore, the pressure resistance of the battery can 10 can be smoothly transmitted to the vent 60, causing smooth breakage of the vent 60.

[0132] In the fourth embodiment, an example is illustrated in which the vent 60 is radially inside the press-fitting outer wall 45 of the cap 40 and is disposed radially outside the electrode connection portions 41 and the intermediate region 49 therebetween.

[0133] However, the vent 60 constituted by the cap 40 is not limited thereto. For example, the vent may be provided in the plug 50 covering the liquid injection port 42, may be constituted by the joining portion of the liquid injection port 42 and the plug 50, or may be constituted by the joining portion (M) of the cap 40 and the battery can 10. That is, according to the embodiment, by embodying the vent structure in the cap 40 itself or the joining portion of the cap 40 and other components, it is possible not to secure a separate volume for the vent structure. Thereby, the energy density of the battery cell can be further increased.

[0134] [Fifth Embodiment] Hereinafter, with reference to FIGS. 36 to 38, a fifth embodiment of the cap will be described.

[0135] The cap of the fifth embodiment is different from that of the fourth embodiment in that the protrusion 43 providing the liquid injection port 42 is directly adjacent to or directly connected to the radially inner part of the intermediate region 49 disposed between the electrode connection parts 41 in the circumferential direction.

[0136] Referring to FIG. 32, in the cap of the fourth embodiment, the protrusion 43 is surrounded by an annular part 55 of the cap 40 that radially separates the protrusion 43 from the intermediate region 49.

[0137] On the other hand, in the cap 40 of the fifth embodiment, as shown in FIG. 37, the protrusion 43 is directly connected to the intermediate region 49 of the cap 40. With such a structure, when heat is generated during welding of the plug 50 to finish the liquid injection port 42, the heat conduction path is defined so that the heat is not substantially conducted toward the electrode assembly but is conducted to the intermediate region 49. Therefore, the adverse effect of the joining heat on the electrode assembly 20 can be further reduced.

[0138] Also, similar to the above-described embodiments, as shown in FIG. 38, since the intermediate regions 49 are adjacent to both sides of the electrode connection part 41 in the circumferential direction, the heat generated when welding the electrode connection part 41 to the tab 27 of the second electrode 22 can be dissipated through the outermost surface 44 of the intermediate region 49. Therefore, the adverse effect of the joining heat on the electrode assembly 20 can be further reduced.

[0139] [Method for manufacturing a battery cell] Since the cap 40 of the above-described embodiment also functions as a current collector plate of the second electrode while having the original function of the cap, it is different from the conventional method for manufacturing a battery cell including a current collector plate for the second electrode and the manufacturing method thereof.

[0140] Also, in the embodiment of the present invention in which the cap 40 is provided with the liquid injection ports 42 and these liquid injection ports 42 can also be used as passages for the joining step of the current collector plate 31 and the first electrode terminal 13, the manufacturing method of the battery cell can be configured more flexibly.

[0141] First, a manufacturing method related to the flowchart of FIG. 39 will be described. This can be applied, for example, when the cap 40 does not have a liquid injection port 42.

[0142] This includes a step of preparing a battery can 10 with a first electrode terminal 13 fixed thereto, and a step of preparing an electrode assembly having a first electrode and a second electrode. At one axial end of the electrode assembly, the first electrode and a current collector can be joined and connected.

[0143] Next, the electrode assembly 20 is inserted into the battery can 10 such that the current collector faces the bottom 12 of the battery can 10, and the current collector plate 31 of the electrode assembly 20 is joined to the first electrode terminal 13 fixed to the bottom 12 of the battery can 10 by a method such as welding.

[0144] Next, an electrolytic solution is injected into the battery can 10 through the open end of the battery can 10.

[0145] Next, the open end of the battery can 10 is covered and shielded with a cap 40. At this time, preferably, the electrode connection portion 41 of the cap 40 and the tab of the second electrode 22 of the electrode assembly 20 are joined in a close contact state. Then, the periphery of the open end of the battery can 10 and the edge of the cap 40 are joined.

[0146] According to these manufacturing methods, separate joining operations for a current collector plate are not required for the second electrode 22.

[0147] Next, a manufacturing method related to the flowchart of FIG. 40 will be described. This can be applied, for example, when the cap 40 has a liquid injection port 42.

[0148] This includes a step of preparing a battery can 10 with a first electrode terminal 13 fixed thereto, and a step of preparing an electrode assembly having a first electrode and a second electrode. At one axial end of the electrode assembly, the first electrode and a current collector can be joined and connected.

[0149] Next, insert the electrode assembly 20 into the battery can 10 such that the current collector faces the bottom 12 of the battery can 10, and join the current collecting plate 31 of the electrode assembly 20 to the first electrode terminal 13 fixed to the bottom 12 of the battery can 10 by a method such as welding.

[0150] Next, cover and shield the open end of the battery can 10 with the cap 40. At this time, preferably, the electrode connection portion 41 of the cap 40 and the tab of the second electrode 22 of the electrode assembly 20 are joined in a state of being in close contact. Then, join the periphery of the open end of the battery can 10 and the edge of the cap 40.

[0151] Next, inject an electrolytic solution into the battery can 10 through the liquid injection port, and seal the liquid injection port 42 with a plug 50 to finish.

[0152] According to these manufacturing methods, there is no need for a separate operation of joining a current collecting plate for the second electrode 22. Moreover, before filling the inside of the battery can 10 with the electrolytic solution, the joining of the cap 40 and the second electrode 22 and the joining of the cap 40 and the battery can 10 can be performed. As a result, it is possible to prevent the joining heat from affecting the electrolytic solution.

[0153] Next, another manufacturing method regarding the flowchart of FIG. 41 will be described. This can be applied, for example, when the cap 40 is provided with the liquid injection port 42.

[0154] This includes a step of preparing the battery can 10 with the first electrode terminal 13 fixed and a step of preparing an electrode assembly including the first electrode and the second electrode. At one end in the axial direction of the electrode assembly, the first electrode and the current collector can be joined and connected. Also, at the other end in the axial direction of the electrode assembly, the electrode connection portion 41 of the cap 40 and the tab of the second electrode can be joined and connected.

[0155] That is, the cap can be joined to the second electrode of the electrode assembly first before housing the electrode assembly in the battery can.

[0156] Next, insert the electrode assembly 20 into the battery can 10 such that the current collector faces the bottom 12 of the battery can 10. During this process, the cap 40 moves to a position covering the open end of the battery can 10.

[0157] Next, join the current collector plate 31 of the electrode assembly 20 to the first electrode terminal 13 fixed to the bottom 12 of the battery can 10 by a method such as welding. Then, join the periphery of the open end of the battery can 10 and the edge of the cap 40.

[0158] Next, inject electrolyte into the battery can 10 through the liquid injection port 42 of the battery can 10, and seal the liquid injection port 42 of the battery can 10 with a plug 50 to finish.

[0159] According to such a manufacturing method, separate joining operations for a current collector plate are not required for the second electrode 22. And before filling the inside of the battery can 10 with electrolyte, joining of the cap 40 and the second electrode 22 and joining of the cap 40 and the battery can 10 can be performed. Therefore, it is possible to prevent the joining heat from affecting the electrolyte. Also, without separately managing the cap 40, it can be integrated with the electrode assembly 20 first, and the assembly equipment can be made simpler.

[0160] [Battery Pack and Vehicle] Referring to FIG. 42, the battery cell 72 to which the above-described cap is applied and / or the battery cell 72 to which the above-described manufacturing method is applied can be housed in the housing 71 of the battery pack 70. The battery pack 70 can also be configured using battery modules which are intermediate forms of assembly, or as shown in the figure, the battery pack 70 can be directly configured without battery modules.

[0161] Since the above-described battery cell 72 is large in volume by itself, it is not particularly difficult to manufacture the battery pack 70 without using an intermediate structure called a battery module. And since the second electrode of the battery cell 72 is connected via a cap, it has less internal resistance and a higher energy density. Therefore, the energy density of the battery pack 70 can be realized to be higher.

[0162] In this way, the battery pack 70 with increased energy density can store the same amount of energy and reduce its volume and weight. Therefore, when the battery pack 70 to which these battery cells 72 are applied is mounted on a vehicle such as an automobile 80 that uses electricity as an energy source as shown in FIG. 43, the mileage of the vehicle with respect to energy can be further expanded.

[0163] It should be understood that the above-described embodiments are illustrative in all respects and not restrictive, and the scope of the present invention is indicated by the claims described below rather than the above detailed description. And of course, the meaning and scope of the claims described below, as well as any changes and deformable forms conceivable from their equivalent concepts, should be construed as being included in the scope of the present invention.

[0164] As described above, the present invention has been described with reference to the illustrative drawings. However, 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 those of ordinary skill in the art within the scope of the technical idea of the present invention. Furthermore, even if the effects of the present invention due to its configuration are not explicitly described while describing the embodiments of the present invention, it is natural that the effects predictable by the configuration should also be recognized.

Claims

1. A battery can including a side wall portion extending axially between a closed first end portion and an open second end portion, wherein the open second end portion defines an opening inside the battery can; An electrode assembly including a first electrode and a second electrode, the electrode assembly being housed inside the battery can, and at least one tab extending from the second electrode being disposed near the open second end portion of the battery can; and A cap disposed to close the open second end portion of the battery can by covering the opening of the second end portion; comprising The cap includes a plurality of electrode connection portions protruding axially into the battery can so as to be in direct electrical contact with at least one tab of the second electrode, The plurality of electrode connection portions are circumferentially spaced apart from each other with respect to the center of the cap, At least two electrode connection portions are respectively disposed on both sides facing each other with respect to the center of the cap, A battery cell.

2. The plurality of electrode connection portions and at least one tab of the second electrode are connected by a welding portion, The battery cell according to Claim 1.

3. The at least one tab includes a plurality of tabs extending in a radial direction orthogonal to the axial direction, and the plurality of tabs at least partially overlap each other in the axial direction, The battery cell according to Claim 1.

4. Each of the plurality of electrode connection portions extends along the radial direction of the cap, The battery cell according to Claim 1.

5. The plurality of electrode connection portions include four electrode connection portions circumferentially spaced apart at equal intervals, The battery cell according to Claim 1.

6. Each of the plurality of electrode connection portions linearly extends along its respective radial direction, The battery cell according to Claim 5.

7. The plurality of electrode connection portions are connected to each other by a protruding portion of the cap in a central region in the radial direction of the cap, The protruding portion of the cap protrudes axially into the battery can, The battery cell according to Claim 1.

8. The plurality of electrode connection portions are connected to each other by a protruding portion of the cap extending along the periphery of an outer region in the radial direction of the cap, The protruding portion of the cap protrudes axially into the battery can, The battery cell according to Claim 1.

9. The cap includes an electrically conductive material, and the electrically conductive material along the outer edge in the radial direction of the cap is in electrical contact with the side wall portion of the battery can at the second end portion. The battery cell according to claim 1.

10. The plurality of electrode connection portions are formed integrally with the electrically conductive material of the cap. The battery cell according to claim 9.

11. Each of the plurality of electrode connection portions corresponds to each recess formed on the outer surface of the cap that extends in a direction away from the inside of the battery can in the axial direction. The battery cell according to claim 10.

12. The cap includes a liquid injection port provided at the central portion of the cap. The battery cell according to any one of claims 1 to 11.

13. The liquid injection port is disposed in a central protruding region of the cap. The central protruding region is disposed further axially outside from the inside of the battery can than the contact surface of each of the plurality of electrode connection portions. The contact surface is in direct electrical contact with at least one tab of the second electrode. The battery cell according to claim 12.

14. An intermediate region of the cap is defined between the electrode connection portions arranged at intervals in the circumferential direction. The intermediate region of the cap is disposed further axially outside from the inside of the battery can than the contact surface of the electrode connection portion. The central protruding region of the cap is disposed radially apart from the intermediate region by an outer surface portion of the cap that is disposed closer to the inside of the battery can in the axial direction than the central protruding region and the intermediate region. The battery cell according to claim 13.

15. An intermediate region of the cap is defined between the electrode connection portions arranged at intervals in the circumferential direction. The intermediate region of the cap is disposed further axially outside from the inside of the battery can than the contact surface of the electrode connection portion. The central protruding region of the cap is directly adjacent to the intermediate region in the radial direction. The battery cell according to claim 13.

16. The cap includes a vent. The vent is disposed radially outside the plurality of electrode connection portions. The battery cell according to claim 1.

17. The first electrode terminal is disposed at the closed first end portion of the battery can, and the first electrode terminal is electrically insulated from the closed first end portion of the battery can. The first electrode of the electrode assembly is electrically connected to the first electrode terminal via a first current collector plate disposed axially between the electrode assembly and the closed first end of the battery can. The battery cell according to claim 1.

18. The cap is formed and arranged such that the outermost surface of the cap disposed axially away from the inside of the battery can is disposed axially further away from the inside of the battery can than the second end of the battery can. The battery cell according to claim 1.

19. At least two of the electrode connection portions are disposed on opposite sides of the center of the cap. The straight line connecting the two electrode connection portions extends through the center of the cap. The battery cell according to claim 1.

20. At least two of the electrode connection portions extend radially. The battery cell according to claim 1.

21. At least two of the electrode connection portions linearly extend along a straight line extending through the center of the cap. The battery cell according to claim 20.

22. A method for manufacturing the battery cell according to claim 1, comprising: Positioning the electrode assembly inside the battery can, positioning the cap so as to cover the opening of the second end of the battery can, and assembling the battery cell by closing the second end of the battery can; After assembling the battery cell, joining a plurality of the electrode connection portions to at least one tab of the second electrode; Joining the cap to the battery can; and Injecting an electrolytic solution into the battery can; A method for manufacturing a battery cell.

23. Injecting the electrolytic solution into the battery can is performed through a liquid injection port provided in the central portion of the cap. The method for manufacturing a battery cell according to claim 22.

24. Covering the liquid injection port with a plug; Further comprising The method for manufacturing a battery cell according to claim 23.

25. Joining a plurality of the electrode connection portions to at least one tab of the second electrode is performed by irradiating a laser on the outer surface of the tab in a direction axially away from the inside of the battery can. The method for manufacturing a battery cell according to claim 22.

26. Including the battery cell of claim 1, A battery pack.

27. Including the battery pack of claim 26, A vehicle. ​

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