Welded structure of battery can and cap and battery cell to which this is applied

Abstract

The present invention relates to a welded structure for a battery can and a cap, and a battery cell using the same. The battery cell includes a can including a bottom member and a sidewall member connected to the bottom member and extending in an axial direction, an electrode assembly housed inside the can, and a cap covering an open end provided at one axial end of the sidewall member. A terminal connector extending outward in the axial direction is provided on a radially outer edge of a current collector plate connected to an electrode of the electrode assembly and disposed near the open end, and contacting and electrically connecting the inner circumferential surface of the sidewall member. The inner circumferential surface of the sidewall member and the outer circumferential surface of the cap are welded to form a weld, with at least a portion of the terminal connector axially interposed between the inner circumferential surface of the sidewall member and the outer circumferential surface of the cap.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0140254 dated October 27, 2022 and Korean Patent Application No. 10-2023-0071732 dated June 2, 2023, and all contents disclosed in the documents of said patent applications are incorporated herein by reference.

[0002] The present invention relates to a welded structure for a battery can and a cap, and a battery cell to which the same is applied. [Background technology]

[0003] The process of manufacturing a battery cell using a cylindrical can includes the steps of deep drawing a metal sheet to form a circular bottom member and a circular tubular side wall member connected to it, accommodating an electrode assembly therein, and then covering the open end of the side wall member with a cap to finish the process.

[0004] Meanwhile, a current collecting plate is provided at one of both axial ends of the electrode assembly toward the open end, contacting and electrically connecting with the electrode tab of the electrode assembly, and is connected to the cap or the side wall member by welding or the like so as to contact and be electrically connected with the cap or the side wall member.

[0005] Referring to FIG. 15, in the process of welding the current collecting plate 32 to the cap 40 or the side wall member 10, the current collecting plate 32 must be kept in close contact with the cap 40 or the side wall member 10. To achieve this, a jig is required to tightly contact the current collecting plate 32 with the cap 40 or the current collecting plate 32 with the side wall member 10, and a mask is also required to expose the welding area.

[0006] In order to closely attach the current collector plate to the cap or sidewall member through the mask or jig, a space must be provided inside the can to accommodate the mask or jig. However, this space remains empty after the mask or jig is removed, resulting in an inefficient use of the internal volume of the can. This hinders designs that aim to increase the energy density per unit volume of the can.

[0007] Furthermore, finishing the open end of the cylindrical can requires a process of connecting the current collector plate to the cap or the sidewall member, and a process of connecting the cap to the sidewall member. These additional steps reduce the production efficiency of cylindrical battery cells and increase the production cost.

[0008] Meanwhile, if the welding heat generated when welding the can and the cap is transferred to the electrode assembly housed inside the can, it may cause deterioration of the separator, deformation or decomposition of the internal structure, etc. Therefore, it is necessary to prevent the welding heat from being transferred to the electrode assembly. Summary of the Invention [Problem to be solved by the invention]

[0009] One aspect of the present invention has been devised to solve the above-mentioned problems, and aims to provide a welded structure for a battery can and a cap, which can be designed to increase the energy density per unit volume of the can without wasting the internal space of the can when welding a current collector plate provided at the open end of the can to the can, and a battery cell using the same.

[0010] Another aspect of the present invention is to provide a welding structure for a battery can and a cap, which integrates the process of welding the current collector plate to the can and the process of welding the cap to the side wall member into a single welding process, thereby improving the production efficiency of cylindrical battery cells and reducing the unit production cost, and a battery cell using the same.

[0011] Another aspect of the present invention is to provide a can and cap welding structure and a battery cell using the same, in which the cap also functions as a jig that presses the current collector plate, eliminating the need for a separate jig that presses the current collector plate for welding.

[0012] Another aspect of the present invention is to provide a can and cap welding structure and a battery cell using the same, which allows heat generated when welding the can and cap to be dissipated through the current collector plate, thereby minimizing damage to the electrode assembly due to heat.

[0013] The technical object of the present invention is not limited to the above-mentioned objects, and other unmentioned objects and advantages of the present invention will be understood from the following description and will become more apparent from the examples of the present invention. Furthermore, it will be easily understood that the objects and advantages of the present invention can be achieved by the means and combinations thereof set forth in the claims. [Means for solving the problem]

[0014] In order to solve the above-mentioned problems, one aspect of the present invention can be applied to a battery cell including a can including a bottom member and a sidewall member connected to the bottom member and extending in an axial direction, an electrode assembly housed inside the can, and a cap covering an open end provided at one axial end of the sidewall member.

[0015] The bottom member may be a flat circular plate, and the side wall member may be a circular tubular member. The can may be formed by deep drawing a metal sheet having nickel (Ni) plated on both surfaces of steel.

[0016] The electrode assembly may be fabricated in a jelly roll shape by sequentially stacking a first electrode, a separator, a second electrode, and a separator and winding the stack around a core.

[0017] The electrode assembly may be cylindrical.

[0018] The cap may be a circular plate made of a metal material.

[0019] A current collecting plate connected to a second electrode of the electrode assembly may be installed at one end of the electrode assembly in the axial direction.

[0020] The current collector is disposed at the open end of the can.

[0021] A terminal connection portion is provided on the radially outer edge of the current collector plate, extending outward in the axial direction and contacting and electrically connecting to the inner circumferential surface of the side wall member.

[0022] Since the terminal connecting portion extends in the axial direction, a sufficient contact area can be ensured between the terminal connecting portion and the side wall member.

[0023] The battery cell has a weld formed by welding the inner surface of the side wall member and the outer surface of the cap, with at least a portion of the terminal connection portion being interposed between the inner surface of the side wall member and the outer surface of the cap in the axial direction.

[0024] The current collecting plate may include an electrode connecting portion connected to the second electrode of the electrode assembly and extending in a radial direction.

[0025] The terminal connecting portion may be disposed radially further outward than the electrode connecting portion.

[0026] The terminal connection portion and the electrode connection portion may be connected to each other via a bent portion provided at a lower end of the terminal connection portion and changing the extending direction of the current collecting plate.

[0027] The terminal connection portion may be provided at a portion of the current collector plate that extends axially outward from the bent portion.

[0028] The side wall member may extend further outward in the axial direction than the terminal connecting portion of the current collector plate.

[0029] The portion of the side wall member that extends further outward in the axial direction melts into the welded portion during welding, thereby increasing the strength and volume of the welded portion.

[0030] The inner diameter of an inner circumferential surface of a section of the side wall member that extends axially further outward than the terminal connecting portion of the current collector plate may be larger than the inner diameter of the inner circumferential surface of the terminal connecting portion.

[0031] As a result, the side wall member does not cover the tip surface in the axial direction from outside in the axial direction the tip surface provided at the axially outer end of the terminal connecting portion of the current collector plate.

[0032] This provides a path for the axially irradiated laser to directly reach the terminal connection portion, making welding of the cap, can, and current collector plate smoother. Also, the inner circumferential surface of the sidewall member of the can first guides the insertion of the cap, and then the inner circumferential surface of the terminal connection portion of the current collector plate guides the insertion of the cap, allowing for smooth central alignment and insertion of the cap.

[0033] The outer circumferential surface of the cap may contact the inner circumferential surface of the terminal connection part, thereby aligning the center of the cap with the can and electrically connecting the terminal connection part to the cap.

[0034] The edge of the cap may be provided with an axially extending abutment portion such that the outer peripheral surface of the cap faces the inner peripheral surface of the side wall member in the radial direction.

[0035] The butt portion extends in the axial direction, so that a sufficient contact area can be secured between the terminal connecting portion and the butt portion.

[0036] The butt portion may extend further outward in the axial direction than the terminal connecting portion of the current collector plate.

[0037] The portion of the butt joint that extends further outward in the axial direction melts into the welded portion during welding, thereby increasing the strength and volume of the welded portion.

[0038] The outer diameter of the outer peripheral surface of the butt portion in a section extending axially further outward than the terminal connecting portion of the current collector plate may be smaller than the outer diameter of the outer peripheral surface of the terminal connecting portion.

[0039] As a result, the abutting portion does not cover the tip surface in the axial direction from outside in the axial direction relative to the tip surface provided on the axially outer edge of the terminal connecting portion of the current collector plate.

[0040] This provides a path through which the axially irradiated laser can directly reach the terminal connection portion, making welding of the cap, can, and current collector plate smoother.

[0041] An axially outer edge of the terminal connecting portion may be positioned further inward in the axial direction than an axially outer edge of the side wall member and an axially outer edge of the butt portion.

[0042] As a result, the inner peripheral surface of the side wall member and the outer peripheral surface of the abutting portion may face each other in the radial direction with a slight gap therebetween, axially outward of the tip end surface of the terminal connecting portion.

[0043] The welded portion may be formed by welding at least the axial outer edge of the inner surface of the side wall member, the axial outer edge of the outer surface of the butt portion, and the axial outer edge of the terminal connecting portion.

[0044] An axially inner end of the abutting portion may be connected to a curved surface portion that is convexly curved inward in the axial direction.

[0045] These curved surfaces provide an elastic force that allows the abutting portion to elastically deform in the radial direction, thereby allowing the curved surfaces of the cap to elastically crimp the terminal connecting portion of the current collector plate to the side wall member.

[0046] The cap can be inserted into the can until the inner axial end of the curved portion interferes with the current collector plate in the axial direction, thereby restricting the insertion depth of the cap relative to the open end.

[0047] Furthermore, since the cap is forcibly inserted radially inward from the terminal connection portion of the current collector plate, the curved surface portion can also apply strong pressure to the current collector plate in the axial direction.

[0048] That is, the cap can function as a jig for pressing and fixing the current collector plate in both the axial and radial directions before welding.

[0049] A receiving portion that extends flatly in the radial direction may be provided on the cap radially inward of the curved surface portion.

[0050] The curved surface portion and the receiving portion may be connected via a first inclined portion that extends more outward in the axial direction as it goes radially inward.

[0051] The first inclined portion further imparts elastic force to the butted portion.

[0052] The axially outer surface of the receiving portion may protrude further outward in the axial direction than the abutting portion of the side wall member, thereby enabling the receiving portion to protect the weld and function as a receiving surface for the battery cell.

[0053] A centripetal portion extending radially is provided radially inward of the receiving portion on the cap, and the receiving portion and the centripetal portion may be connected via a second inclined portion extending axially inward as they move radially inward.

[0054] This can further increase the overall rigidity of the cap.

[0055] The second inclined portion may have a gentler inclination than the first inclined portion.

[0056] The steep inclination of the first inclined portion provides elastic force in the radial direction, while the gentle inclination of the second inclined portion is advantageous in ensuring the rigidity of the cap.

[0057] An aspect of the present invention further provides a method for manufacturing the above-described battery cell.

[0058] This includes the steps of inserting the current collector into the can so that the outer peripheral surface of the terminal connection portion of the current collector contacts the inner peripheral surface of the side wall member, inserting the cap into the can so that the outer peripheral surface of the cap contacts the inner peripheral surface of the terminal connection portion of the current collector inserted into the can, and irradiating a laser in the axial direction to an area where the outer peripheral surface of the side wall member and the inner peripheral surface of the can face each other to form a weld.

[0059] In one aspect of the present invention, a current collecting plate is connected to an electrode tab provided at one of both axial ends of the electrode assembly that faces the open end.

[0060] The current collecting plate includes an electrode connecting portion that extends radially and contacts and is electrically connected to the electrode tab, and a terminal connecting portion that extends axially outward at the radial outer edge of the second electrode connecting portion and contacts and is electrically connected to the inner circumferential surface of the side wall member.

[0061] Then, the inner surface of the side wall member and the outer surface of the cap are welded together with at least a portion of the second terminal connecting portion interposed between the inner surface of the side wall member and the outer surface of the cap in the axial direction.

[0062] This allows the can and cap to be seam-welded in a single process of welding the inner circumferential surface of the side wall member and the outer circumferential surface of the cap, and also allows the terminal connection portion of the current collector plate to contact the side wall member and / or the cap, thereby electrically connecting them.

[0063] The cap may have an axially extending abutment portion such that its outer peripheral surface faces the inner peripheral surface of the side wall member in the radial direction.

[0064] The terminal connecting portion of the current collector plate may be interposed between an inner peripheral surface of the side wall member and an outer peripheral surface of the butting portion.

[0065] The axially outer edge of the inner peripheral surface of the side wall member and the axially outer edge of the outer peripheral surface of the butt portion 4 may be laser welded together with the second terminal connecting portion interposed therebetween.

[0066] In this case, the axial outer edge of the inner peripheral surface of the side wall member, the axial outer edge of the outer peripheral surface of the butt portion, and the axial outer edge of the second terminal connecting portion may be laser welded together.

[0067] The axially inner end of the butt portion may be connected to a curved surface portion that extends radially inward, but whose outer peripheral surface has a tangent whose inclination gradually decreases as it goes axially inward.

[0068] The insertion depth of the cap into the open end may be restricted by an axially inner end of the curved portion interfering with an electrode connecting portion of the current collector plate.

[0069] A receiving portion extending flatly in the radial direction may be provided radially inward of the curved portion of the cap, and a first inclined portion extending axially outward may be provided between the curved portion and the receiving portion, the further radially inward it goes.

[0070] As a result, the curved portion and the first inclined portion may form a gooseneck shape that is easily elastically deformed in the radial direction but has excellent elastic recovery. When the cap is inserted into the open end, the curved portion elastically deforms to allow the butt portion to displace radially inward, and the butt portion can strongly crimp the terminal connecting portion of the current collector plate radially outward. In other words, the butt portion can function as a jig that tightly presses the terminal connecting portion against the side wall member.

[0071] A centripetal portion extending flatly in the radial direction may be provided radially inward of the receiving portion on the cap, and a second inclined portion extending axially inward as it goes radially inward may be provided between the receiving portion and the centripetal portion.

[0072] The inclination of the first inclined portion may be greater than the inclination of the second inclined portion, so that when the cap is subjected to a load in the radially inward direction, deformation is more concentrated on the first inclined portion than on the second inclined portion, and the butting portion can more reliably perform the function of a jig to press the terminal connecting portion against the side wall member.

[0073] An axially outer edge of the terminal connecting portion may be disposed axially further inward than an axially outer edge of the side wall member and an axially outer edge of the butt portion.

[0074] The sidewall member and the cap may be made of the same metal material, for example, aluminum or steel.

[0075] The current collecting plate may be made of the same metal material as the side wall member and the cap.

[0076] Alternatively, the current collecting plate may be made of a different metal material from the sidewall member and the cap, for example, copper.

[0077] Then, even though they are made of different materials, the axial ends of the side wall member and the cap are welded to each other, and the current collecting plate can be maintained in a state interposed therebetween. [Effects of the Invention]

[0078] According to one aspect of the present invention, when welding the current collector plate located at the open end of the can to the can, the cap also functions as a jig, eliminating the need to provide additional space to accommodate the jig and saving internal space in the can, thereby increasing the energy density per volume of the battery cell.

[0079] Furthermore, according to one aspect of the present invention, the axial ends of the side wall member and the cap are welded together with the current collector plate interposed between them, thereby completing the process of welding the current collector plate to the can and the process of welding the cap to the side wall member in a single welding process, thereby improving the production efficiency of cylindrical battery cells and reducing the unit production cost.

[0080] In addition, according to one aspect of the present invention, since the current collector plate is tightly attached to the welded portion between the can and the cap, heat generated when welding the can and the cap is dissipated through the current collector plate, thereby preventing or minimizing the phenomenon of the welding heat being conducted through the side wall member and causing thermal damage to the separator of the electrode assembly.

[0081] Furthermore, according to one aspect of the present invention, welding is performed with the current collector plate firmly pressed between the can and the cap, so that the current collector plate acts as a barrier to prevent the welding laser from entering the inside of the cap.

[0082] The above-mentioned effects and specific effects of the present invention will be described in conjunction with the following description of the preferred embodiment of the invention. [Brief explanation of the drawings]

[0083] [Figure 1] FIG. 1 is a perspective view of a cylindrical battery cell according to an embodiment. [Figure 2] 2 is an exploded perspective view of the electrode assembly housed inside the can of FIG. 1 before being wound up. FIG. [Figure 3] FIG. 3 is a perspective view of the electrode assembly of FIG. 2 in a stacked state before being wound up. [Figure 4] FIG. 4 is a perspective view of the laminate of FIG. 3 wound up to assemble a cylindrical jelly roll-type electrode assembly. [Figure 5] 10 is a perspective view showing a state in which a first current collecting plate is joined to an electrode tab of a first electrode of the electrode assembly. FIG. [Figure 6] 10 is a perspective view showing a state in which a second current collecting plate is joined to an electrode tab of a second electrode of the electrode assembly. FIG. [Figure 7]10 is a side cross-sectional view showing a process of placing an electrode assembly to which a current collector plate is joined into a can. FIG. [Figure 8] 5A to 5C are side cross-sectional views illustrating a process of joining a first current collector plate and a first electrode terminal of an electrode assembly housed in a can. [Figure 9] 10 is a side cross-sectional view showing a process of covering the open end of the can housing the electrode assembly with a cap. FIG. [Figure 10] 10 is an enlarged cross-sectional view showing an open end portion of a battery cell in which the open end of the can is covered with a cap. FIG. [Figure 11] FIG. 10 is an enlarged cross-sectional view of the edge of the cap. [Figure 12] FIG. 4 is an enlarged cross-sectional view showing a state in which the cap is inserted into the can. [Figure 13] 11 is an enlarged view showing a side wall member, a current collector plate, and a cap portion to be welded in the battery cell of FIG. 10; [Figure 14] 14 is a view showing a state in which a side wall member, a current collecting plate, and a cap portion in FIG. 13 are welded to form a welded portion. [Figure 15] 10 is a diagram showing a coupling structure between a can and a current collector plate of a battery cell according to a comparative example; [Figure 16] 1 is a flow chart of a manufacturing process for a battery cell according to one embodiment of the present invention. [Figure 17] 1 is a diagram showing a battery pack to which a battery cell according to an embodiment of the present invention is applied; [Figure 18] 1 is a diagram showing an automobile equipped with a battery pack to which a battery cell according to an embodiment of the present invention is applied; DETAILED DESCRIPTION OF THE INVENTION

[0084] The above-mentioned objects, features, and advantages will be described in detail below with reference to the accompanying drawings, so that those skilled in the art can easily implement the technical concept of the present invention. In describing the present invention, if a detailed description of known technologies relating to the present invention is deemed to obscure the gist of the present invention, the detailed description will be omitted. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings are used to indicate the same or similar components.

[0085] Although terms such as "first" and "second" are used to describe various components, it is understood that these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless otherwise specified, a first component may also be a second component.

[0086] Throughout the specification, unless otherwise specified, each element may be singular or plural.

[0087] Hereinafter, when an arbitrary structure is arranged "on top (or bottom)" of a component or "above (or below)" a component, it means that the arbitrary structure is not only arranged in contact with the upper surface (or lower surface) of the component, but also that other structures may be interposed between the component and the arbitrary structure arranged above (or below) the component.

[0088] Furthermore, when a component is described as being "coupled," "coupled," or "connected" to another component, it should be understood that the components may be directly coupled or connected to each other, but that other components may be "intervening" between the components, or that each component may be "coupled," "coupled," or "connected" via other components.

[0089] As used herein, singular expressions include plural expressions unless the context clearly dictates otherwise. Terms such as "comprise" or "include" in this application should not be interpreted as including all of the multiple components or multiple steps described in the specification, but should be interpreted as meaning that some of the components or some of the steps may not be included, or that additional components or steps may be included.

[0090] In the entire specification, "A and / or B" means A, B, or A and B, unless otherwise specified; and "C to D" means C or more and D or less, unless otherwise specified.

[0091] In describing the embodiments, the axial direction refers to the direction in which the axis that forms the winding center of the jelly roll-type electrode assembly extends, the radial direction refers to the direction toward (centripetal) or away (centrifugal) from the axis, and the circumferential direction refers to the direction surrounding the axis.

[0092] Hereinafter, examples of battery cells to which welding structures according to embodiments of the present invention are applied will be described in detail with reference to FIGS.

[0093] The battery cell of the embodiment may be, for example, a cylindrical battery cell having a form factor ratio (defined as the diameter of a cylindrical battery cell divided by its height, i.e., the ratio of the diameter (Φ) to the height (H)) greater than approximately 0.4.

[0094] Here, the form factor refers to a value indicating the diameter and height of a cylindrical battery cell. The cylindrical battery cell may be, for example, a 46110 cell, a 48750 cell, a 48110 cell, a 48800 cell, or a 46800 cell. In the form factor value, the first two digits indicate the diameter of the cell, the next two digits indicate the height of the cell, and the final 0 indicates that the cross section of the cell is circular.

[0095] The battery cell may be a cylindrical battery cell having a substantially cylindrical shape with a diameter of approximately 46 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0096] A battery cell according to another embodiment may be a cylindrical battery cell that is approximately cylindrical, with a diameter of approximately 48 mm, a height of approximately 75 mm, and a form factor ratio of 0.640.

[0097] In yet another embodiment, the battery cell may be a cylindrical battery cell that is approximately cylindrical, has a diameter of approximately 48 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0098] In yet another embodiment, the battery cell may be a cylindrical battery cell that is approximately cylindrical, with a diameter of approximately 48 mm, a height of approximately 80 mm, and a form factor ratio of 0.600.

[0099] In yet another embodiment, the battery cell may be a cylindrical battery cell that is approximately cylindrical, with a diameter of approximately 46 mm, a height of approximately 80 mm, and a form factor ratio of 0.575.

[0100] Of course, one aspect of the present invention can be applied to battery cells with a form factor ratio of approximately 0.4 or less, such as 18650 cells and 21700 cells. For an 18650 cell, the diameter is approximately 18 mm, the height is approximately 65 mm, and the form factor ratio is 0.277. For a 21700 cell, the diameter is approximately 21 mm, the height is approximately 70 mm, and the form factor ratio is 0.300.

[0101] The battery cell of the embodiment includes an electrode assembly 20, current collector plates 31 and 32 electrically connected to the electrode assembly 20, and a can 10 that houses the electrode assembly 20 and the current collector plates 31 and 32.

[0102] The can 10 includes a bottom member 12 and an axially extending sidewall member 11 connected to the bottom member 12.

[0103] The open end provided at one end of the side wall member 11 in the axial direction is covered and sealed with a cap 16 after the electrode assembly 20 is accommodated in the can 10 .

[0104] The bottom member 12 may be disk-shaped with a hole formed in the center, and the side wall member 11 may be circular tubular.

[0105] The bottom member 12 and the side wall member 11 can be manufactured by forming a metal sheet in which the surface of steel is nickel-plated by a deep drawing process, and then trimming the leading end of the side wall member 11 with a punch while holding it with a blank holder. Of course, the material of the can 10 is not limited to this.

[0106] A first electrode terminal 13 may be inserted into the hole and coupled thereto. The first electrode terminal 13 may be riveted to the bottom member 12 with a gasket 14 interposed therebetween. The gasket 14 is interposed between the first electrode terminal 13 and the bottom member 12 to seal the inside and outside of the can 10, prevent tearing of the electrolyte, and electrically insulate the first electrode terminal 13 from the bottom member 12.

[0107] However, the method of connecting the first electrode terminal 13 and the bottom member 12 is not limited thereto. For example, various other fastening methods, such as a bolt and nut fastening method, a glass seal method, or a chrome coating and PP-MAH thermal bonding method, may be used as long as the structure can seal the gap between the first electrode terminal 13 and the bottom member 12 and electrically insulate the first electrode terminal 13 from the bottom member 12.

[0108] The first electrode terminal 13 may have a first polarity, and the battery can 10 may have a second polarity. That is, the bottom member 12 of the battery can 10, the side wall member 11 connected thereto, and the cap 16 (described later) connected to the side wall member 11 may all have the second polarity.

[0109] Accordingly, the first electrode terminal 13 and the second electrode terminal 15 may both be disposed at the axial end, i.e., the closed end, of the battery cell, where the bottom member 12 is provided. 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 the top of the battery cell.

[0110] In one example, the first electrode terminal 13 may be a positive terminal and the second electrode terminal 15 may be a negative terminal, or vice versa.

[0111] An electrode assembly 20 is accommodated within the battery can 10. The electrode assembly 20 is manufactured by preparing a first electrode 21, a second electrode 22, and a separator 28 that are each longitudinally extending and have a predetermined width, as shown in Fig. 2, stacking the first electrode 21, the separator 28, the second electrode 22, and the separator 28 in this order, as shown in Fig. 3, and then winding the stack around a core shaft to form a jelly roll, as shown in Fig. 4.

[0112] The first electrode 21 may be a positive electrode and the second electrode 22 may be a negative electrode, or vice versa.

[0113] The first electrode 21 and the second electrode 22 are fabricated in the form of sheets. The electrode sheets are fabricated by coating an active material layer 24 on the surface of a metal foil 23. The electrode sheets have a coated portion 25 where the active material layer 24 is coated and an uncoated portion 26 where the active material layer 24 is not coated. The positive electrode sheet has the uncoated portion 26 on one side in the width direction, and the negative electrode sheet has the uncoated portion 26 on the other side in the width direction.

[0114] The uncoated area 26 is exposed or protrudes in the width direction of the laminate. The uncoated area 26 itself functions as an electrode tab 27.

[0115] Notches can be formed at predetermined intervals in the plain portion 26 to form flag-shaped notched tabs 27.

[0116] In the embodiment, the notched tab 27 is shaped like an equilateral trapezoid, but may have various other shapes such as a semicircle, an inverse ellipse, a triangle, a rectangle, or a parallelogram.

[0117] In the embodiment, the notched tabs 27 arranged along the length direction have the same width. However, the width of the notched tabs may be gradually or stepwise increased from the core side to the outer periphery side.

[0118] In the embodiment, the height of the notched tabs 27 increases stepwise from the core side to the outer periphery side, but the height of the notched tabs may be constant or may decrease gradually.

[0119] In the embodiment, a structure is shown in which the notched tabs 27 are omitted from a predetermined section of the centripetal end and a predetermined section of the distal end of the non-coated portion 26. However, it goes without saying that the notched tabs at the centripetal end of the non-coated portion do not have to be omitted, and the notched tabs at the distal end of the non-coated portion do not have to be omitted.

[0120] In the jellyroll-type electrode assembly 20, the notched tabs 27 may be flattened by bending them radially, as shown in Fig. 4. The notched tabs 27 may be bent radially inward or outward. In this embodiment, the notched tabs 27 may be bent radially inward.

[0121] The notched tabs 27 may be bent one by one during the process of winding the laminate to form the jelly roll type electrode assembly 20. Alternatively, the notched tabs 27 may be bent all at once after winding the laminate to form the jelly roll type electrode assembly.

[0122] In this way, the notched tabs 27 of the first electrode 21 and the notched tabs 27 of the second electrode 22, which are folded radially and overlapped, can each provide a plane substantially perpendicular to the axial direction at both axial ends of the electrode assembly 20.

[0123] As shown in Figures 5 and 6, a first current collecting plate 31 and a second current collecting plate 32 may be bonded to the substantially flat surfaces formed by bending the notched tabs 27 exposed at both axial ends of the electrode assembly 20.

[0124] In this embodiment, the first current collector 31 is a positive current collector, and the second current collector 32 is a negative current collector. The first current collector 31 may be made of aluminum, and the second current collector 32 may be made of copper.

[0125] The current collecting plates 31, 32 can be made by stamping, trimming, piercing and bending a metal sheet.

[0126] 5, the current collecting plate 31 includes terminal connecting portions 312 extending radially from a center, a ring portion 313 circumferentially connecting the distal edges of the first terminal connecting portions 312, and a first electrode connecting portion 314 extending centripetally from the ring portion 313 but not connected to the first terminal connecting portion 312. The center of the first terminal connecting portion 312 covers at least a portion of the hollow portion of the winding core of the electrode assembly 20.

[0127] The first electrode connector 314 is joined to the notched tab 27 of the first electrode 21 of the electrode assembly 20 by laser welding or the like before the electrode assembly 20 is placed in the can 10. The laser welding lines may extend radially.

[0128] 6, the second current collecting plate 32 defines a hole 322 corresponding to the hollow portion of the winding core of the electrode assembly 20 and includes an inner ring portion 321 provided in a shape surrounding the hollow portion of the winding core, a second electrode connecting portion 323 extending radially from the inner ring portion 321, and a second terminal connecting portion 324 disposed on the distal side of the second electrode connecting portion 323 and connected to the inner ring portion 321. The second terminal connecting portion 324 has an outer ring shape surrounding the edge of the second current collecting plate 32.

[0129] The second electrode connector 323 may be joined to the notched tab 27 of the second electrode 22 of the electrode assembly 20 by a method such as laser welding before the electrode assembly 20 is placed in the can 10. The laser welding lines may extend radially.

[0130] 7 and 8, the electrode assembly 20 is housed in the can 10 with the first current collecting plate 31 aligned toward the bottom member 12 of the can 10. At this time, an insulator 19 is interposed between the first current collecting plate 31 and the bottom member 12 of the can 10 to electrically insulate the first current collecting plate 31 from the bottom member 12.

[0131] The terminal connection portion 312 of the current collector plate 31 is joined to the first electrode terminal 13 fixed to the battery can 10 by resistance welding, ultrasonic welding, laser welding, or the like. To weld the current collector plate 31 and the first electrode terminal 13, a welding device may be used from the open end of the can 10, through the hollow portion of the core of the electrode assembly 20, and approach the back surface of the center of the first terminal connection portion 312 of the first current collector plate 31. Of course, the current collector plate 31 and the first electrode terminal 13 may also be joined by other methods such as brazing or soldering. In other words, various methods may be used to join the current collector plate 31 and the first electrode terminal 13 as long as they are capable of electrically connecting and fixing them to each other.

[0132] However, the present invention does not exclude a structure in which the positive electrode tab is electrically connected directly to the positive electrode terminal without the positive electrode current collector plate.

[0133] When the electrode assembly 20 is housed inside the can 10 , the electrode tab 27 of the second electrode 22 and the second current collector plate 32 are disposed to face the open end of the sidewall member 11 .

[0134] After the first current collector plate 31 and the first electrode terminal 13 are joined, an electrolyte may be poured into the can 10. After the electrolyte is poured, the open end of the side wall member 11 is finished by being covered with a cap 16, as shown in FIG.

[0135] Of course, the welding structure according to the embodiment of the present invention can also be applied to a method in which the cap 16 is first covered, the electrolyte is poured, and the pouring hole of the cap 16 is then finished.

[0136] The edge of the cap 16 is joined to the edge of the side wall member 11 by laser seam welding, as shown in FIG. 10, so that the can 10 can be sealed.

[0137] A welding structure for a can and a cap according to one embodiment of the present invention will be described in detail below with reference to FIGS.

[0138] The second current collecting plate 32 includes a second electrode connecting portion 323 that contacts and is electrically connected to the electrode tab 27 of the second electrode 22 of the electrode assembly 20, and a second terminal connecting portion 324 that contacts and is electrically connected to the inner peripheral surface of the side wall member 11.

[0139] The second electrode connector 323 may have a circular plate structure extending in the radial direction, and the bottom surface of the second electrode connector 323 may be welded to the surface of the second electrode tab 27 by a method such as laser welding.

[0140] The second terminal connecting portion 324 extends outward in the axial direction from a bent portion 328 provided on the radially outer edge of the second electrode connecting portion 323 .

[0141] The material of the second current collector plate 32 may be softer than the material of the side wall member 11 .

[0142] If the outer diameter of the second terminal connecting portion 324 is set to be much larger than the inner diameter of the inner circumferential surface of the side wall member 11, then during the process of inserting the second current collecting plate 32, the bent portion 328 is elastically deformed, and the second terminal connecting portion 324 is pressed into the inner circumferential surface of the side wall member 11, so that the second terminal connecting portion 324 and the side wall member 11 come into close contact in the radial direction. As a result, the outer diameter of the second terminal connecting portion 324 can correspond to the inner diameter of the side wall member 11 when the second current collecting plate 32 is inserted.

[0143] When the electrode assembly 20 is housed inside the can 10 , the second electrode tab 27 and the second current collecting plate 32 are disposed toward the open end of the side wall member 11 .

[0144] The side wall member 11 extends further outward in the axial direction than the second terminal connecting portion 324 of the second current collecting plate 32. As a result, as shown in Fig. 12, the inner peripheral surface of the side wall member 11 of the can 10 first guides the insertion of the cap 40, and then the inner peripheral surface of the second terminal connecting portion 324 of the second current collecting plate 32 guides the insertion of the cap 40. In other words, the above structure is not only advantageous for welding, which will be described later, but also makes it easier to align the center of the cap by guiding the insertion of the cap 40.

[0145] The open end of the side wall member 11 is finished by being covered with a cap 40. The cap 40 is a lid for the open end having a substantially disk shape. Referring to Fig. 11, the cap 40 includes, from the outside to the inside in the radial direction, a butting portion 49, a curved portion 48, a first inclined portion 47, a receiving portion 45, a second inclined portion 43, and a centripetal portion 41, in this order.

[0146] The cap 40 has an axially extending butt portion 49 on its radially outer edge, the outer peripheral surface of which faces the inner peripheral surface of the side wall member 11 of the can 10 in the radial direction.

[0147] When the cap 40 is inserted into the can 10, the axial outer edge of the inner peripheral surface of the side wall member 11 and the axial outer edge of the outer peripheral surface of the butt portion 49 may be arranged so that their heights correspond to each other.

[0148] At least a partial section of the second terminal connecting portion 324 in the axial direction is radially interposed between the side wall member 11 and the abutting portion 49 and is radially compressed by them.

[0149] In one embodiment, the axial outer edge of the second terminal connecting portion 324 is positioned axially further inward than the axial outer edge of the side wall member 11 and the axial outer edge of the butt portion 49.

[0150] However, the present invention is not necessarily limited to these height relationships. For example, the height of the axial outer edge of the second terminal connecting portion 324 may correspond to the height of the axial outer edge of the side wall member 11 and / or the height of the axial outer edge of the abutting portion 49, and may of course protrude higher than that, if necessary.

[0151] However, if the height of the axial outer edge of the second terminal connecting portion 324 is slightly lower than the height of the axial outer edge of the side wall member 11 and the axial outer edge of the butt portion 49, a groove is formed between the axial outer edge of the side wall member 11 and the axial outer edge of the butt portion 49, and the molten metal of the axial outer edge of the side wall member 11 and the axial outer edge of the butt portion 49 melts into these grooves and welds, so that the axial outer edge of the second terminal connecting portion 324 is not exposed to the outside after welding.

[0152] A curved surface portion 48 is connected to the inner end portion in the axial direction of the butt portion 49, and extends radially inward as it goes axially inward.

[0153] The curved surface portion 48 may be downwardly convex, that is, the inclination of the tangent to the outer circumferential surface thereof may gradually decrease with increasing distance from the butt portion 49. Because the butt portion 49 extends perpendicular to the axial direction, the inclination of the tangent to the outer circumferential surface of the curved surface portion 48 may gradually decrease from 90 degrees with increasing distance from the butt portion 49.

[0154] The curved surface portion 48 may extend to a point where the inclination of the tangent is 0 degrees. More preferably, the curved surface portion 48 may extend further beyond 0 degrees, up to an angle where the inclination of the tangent corresponds to a first inclination of the first inclined portion 47, which will be described later.

[0155] The point on the curved surface portion 48 where the inclination of the tangent line becomes 0 degrees may be a portion on the curved surface portion 48 that extends to the innermost position in the axial direction.

[0156] The insertion depth of the cap 40 into the open end may be restricted by the axial inner end of the curved portion 48, i.e., the point where the inclination of the tangent becomes 0 degrees, interfering with the surface of the second electrode connecting portion 323 of the current collecting plate 32.

[0157] The cap 40 presses the second terminal connecting portion 324 of the second current collector plate 32 in the centrifugal direction, and presses the vicinity of the centrifugal side edge of the second electrode connecting portion 323 of the second current collector plate 32 inward in the axial direction. As a result, the second terminal connecting portion 324 of the second current collector plate 32 is firmly and tightly fixed between the side wall member 11 and the cap 40.

[0158] Unlike the cap 40, the second current collecting plate 32 itself does not need to have enough rigidity to exert an elastic force to strongly press the second terminal connecting portion 324 of itself against the side wall member 11.

[0159] Therefore, if the shape of the cap 40, which has higher rigidity than the second current collector plate 32, is designed to have elasticity, not only will the cap 40 be strongly pressed against the side wall member 11, but the second current collector plate 32, which must be strongly pressed against the side wall member 11 in order to be welded to it, will also be strongly pressed against the side wall member 11 by the cap 40, so that the cap 40 can also function as a jig for welding the second current collector plate 32 to the side wall member 11.

[0160] A receiving portion 45 extending horizontally in the radial direction is provided on the cap 40 radially inward of the curved surface portion 48. The surface of the receiving portion 45 has a flat ring shape, and therefore functions as a leg of the battery cell when the battery cell shown in FIG.

[0161] As shown in the figure, the axial outer surface of the receiving portion 45 is disposed at the same height as the axial outer edge of the butt portion 49, or is disposed further outward in the axial direction. Therefore, even if the battery cell shown in FIG. 1 is turned upside down and the battery cell is placed with the cap 40 in contact with the bottom, the welded portion between the cap 40 and the can 10 does not directly support the load of the battery cell, and the welded portion can be protected.

[0162] Between the curved surface portion 48 and the receiving portion 45, a first inclined portion 47 is provided, which extends radially inward and axially outward, but has a constant inclination of substantially the first inclination. In the embodiment, the first inclination is, for example, approximately 45 degrees. Then, the angle between the first inclined portion 47 and the abutting portion 49 can be approximately 45 degrees.

[0163] A centripetal portion 41 extending horizontally in the radial direction is provided radially inward of the receiving portion 45 in the cap 40. The axial inner surface of the centripetal portion 41 is positioned further axially outward than the axial inner end of the curved surface portion 48.

[0164] As a result, when the cap 40 is pressed in, the curved portion 48 may come into contact with the second current collecting plate 32 before the axial inner surface of the centripetal portion 41 comes into contact with the second current collecting plate 32. That is, according to the embodiment, the insertion depth of the cap 40 may be limited by the interference between the curved portion 48 and the second electrode connecting portion 323 of the second current collecting plate 32.

[0165] Between the receiving portion 45 and the centripetal portion 41, a second inclined portion 43 is provided, which extends inward in the axial direction as it goes inward in the radial direction, but the inclination is substantially the second inclination, and is constant. In the embodiment, the second inclination is, for example, approximately 22.5 degrees.

[0166] The second inclination may be smaller than the first inclination. This allows the radial ends of the first inclined portion 47 to deform more than the radial ends of the second inclined portion 43 when the cap 40 is subjected to a radial load. The difference in these inclinations further ensures that the butt portion 49 of the cap 40 functions as a jig to press the second terminal connecting portion 324 of the second current collecting plate 32.

[0167] The radial length of the receiving portion 45 may be at least twice as long as the length of the section occupied in the radial direction by the butt portion 49, the curved surface portion 48, and the first inclined portion 47. In this case, the receiving portion 45 has relatively higher rigidity in the radial direction, so that the radial load applied to the outer peripheral surface of the cap 40 can be concentrated in the radially outer section rather than the receiving portion 45. This difference in length also further ensures that the butt portion 49 of the cap 40 functions as a jig to press the second terminal connecting portion 324 of the second current collector plate 32.

[0168] 12, when a load is applied to the butt portion 49 in the radially inward direction, the curved portion 48 is mainly elastically deformed, and the connecting portion between the first inclined portion 47 and the receiving portion 45 is mainly elastically deformed. Furthermore, with these neck structures, the elastic deformation section is large, and therefore a large elastic force is also applied to the butt portion 49 in the direction of restoring itself further in the radially outward direction.

[0169] As a result, when the cap 40 is pressed into the open portion of the can 10, the elastic force of the cap 40 acts in a direction to restore the butt portion 49 radially outward, and the second terminal connecting portion 324 of the second current collecting plate 32 is strongly pressed against the side wall member 11 and the butt portion 49, as shown in FIG. 13 .

[0170] In this state, the axial end of the side wall member 11 and the axial end of the butt portion 49 are welded by a laser (L) irradiated in the axial direction, as shown in Fig. 13. The irradiation direction of the laser may be aligned with the axial direction.

[0171] As a result, the inner peripheral surface of the side wall member 11 and the outer peripheral surface of the cap 40 are welded together to form welded portions (W) with at least a partial section of the second terminal connecting portion 324 axially interposed between the inner peripheral surface of the side wall member 11 and the outer peripheral surface of the cap 40. A partial section of the second terminal connecting portion 324 may also be melted into these welded portions (W).

[0172] The portion of the side wall member 11 that extends further outward in the axial direction and the portion of the butt portion 49 face each other radially with a slight gap between them, providing a path through which the laser irradiated in the axial direction can directly reach the second terminal connection portion 324, allowing the second current collecting plate 32 to be heated before excessive heat is generated, making the triple welding of the cap 40, the can 10, and the second current collecting plate 32 smoother.

[0173] Furthermore, the portion of the side wall member 11 that extends further outward in the axial direction and the portion of the butt joint 49 melt into the welded portion (W) during welding, increasing the strength and volume of the welded portion (W).

[0174] The side wall member 11 and the cap 40 may be made of the same metal material, for example, aluminum or steel.

[0175] The second current collecting plate 32 may be made of the same metal material as the side wall member 11 and the cap 40. In this case, the second current collecting plate 32 may be welded together with the side wall member 11 and the cap 40 in the process of welding them together.

[0176] Alternatively, the second current collecting plate 32 may be made of a different metal material from the sidewall member 11 and the cap 40, for example, copper.

[0177] Therefore, even though the second current collecting plate 32 is made of a different material, it can be welded together in the process of welding the side wall member 11 and the cap 40. Even if the welding of the second current collecting plate 32 is somewhat insufficient due to the fact that it is made of a different material, the axial ends of the side wall member 11 and the cap 40 are welded to each other, and the current collecting plate can be maintained in a state interposed therebetween, so there is no problem with the electrical connection between the current collecting plate and the can.

[0178] An example of a method for manufacturing a battery cell according to one aspect of the present invention will now be described with reference to FIG.

[0179] First, the first electrode terminal 13 is fixed to a hole provided in the bottom member 12 of the can 10. At this time, a gasket 14 is interposed between the bottom member 12 and the electrode terminal 13 to provide electrical insulation and sealing therebetween. In the embodiment, the first electrode terminal 13 is fixed by a rivet with the gasket 14 interposed therebetween, but it goes without saying that various other known methods for fixing the first electrode terminal 13 to the bottom member 12 while providing insulation and sealing can be applied.

[0180] Next, the electrode assembly 20 with the current collectors 31 and 32 welded to both ends is inserted into the can. Then, the first current collector 31 faces and contacts the first electrode terminal 13, the second electrode connecting portion 323 of the second current collector 32 faces the open end, and the second terminal connecting portion 324 of the second current collector 32 contacts the inner circumferential surface of the sidewall member 11 of the can 10. In this state, the first current collector 31 and the first electrode terminal 13 are welded together.

[0181] Next, the cap 40 is inserted into the open end of the can 10. The outer circumferential surface of the cap 40 is provided with a curved portion 48 whose outer diameter gradually decreases inward in the axial direction, so that the inner edge of the outer axial end of the second terminal connecting portion 324 of the second current collector plate 32 is naturally pressed by the curved portion 48, and the second terminal connecting portion 324 contacts the abutment portion 49 of the cap 40 and is pressed radially outward. The cap 40 may be inserted until the curved portion 48 of the cap 40 interferes with the second electrode connecting portion 323 in the axial direction.

[0182] Next, the axial end of the side wall member 11 of the can 10 and the axial end of the butt portion 49 of the cap 40 are welded together.

[0183] 15, the battery cell of this embodiment differs from the battery cell of the comparative example in that the cap 40 also functions as a jig when welding the second current collector plate 32 to the can 10, eliminating the need to provide additional space inside the can to accommodate the jig. This makes it possible to increase the energy density relative to the volume of the battery cell without wasting internal space in the can 10.

[0184] 15, the battery cell of the embodiment accomplishes the steps of welding the second current collecting plate 32 to the can 10 and welding the cap 40 to the sidewall member 11 by welding the axial ends of the sidewall member and the cap with the second current collecting plate 32 interposed between them, in a single welding step. This improves the production efficiency of cylindrical battery cells and reduces the unit production cost.

[0185] The battery cells 72 manufactured by the above-described welding structure and welding process can be housed in a housing 71 of a battery pack 70 as shown in Fig. 17. The battery pack 70 can be constructed using a battery module, which is an intermediate form of assembly, or the battery pack 70 can be directly constructed without a battery module as shown.

[0186] The battery cell 72 has a large volume by itself, so it is not particularly difficult to implement the battery pack 70 without using an intermediate structure such as a battery module. The battery cell 72 also has low internal resistance and a high energy density. As a result, the energy density of the battery pack 70 including the battery cell 72 can be further increased.

[0187] In this way, the battery pack 70 with increased energy density can store the same amount of energy while reducing its volume and weight. Therefore, when the battery pack 70 using these battery cells 72 is installed in a vehicle such as an automobile 80 that uses electricity as its energy source, as shown in Fig. 18, the vehicle's mileage per unit of energy can be further increased.

[0188] It should be understood that the above-described embodiments are illustrative in all respects and are not limiting, and the scope of the present invention is defined by the following claims rather than the above detailed description. All modifications and variations within the meaning and scope of the following claims, as well as equivalent concepts, should be construed as being included within the scope of the present invention.

[0189] Although the present invention has been described above with reference to illustrative drawings, the present invention is not limited to the embodiments and drawings disclosed in this specification, and it is obvious that various modifications can be made by those skilled in the art within the scope of the technical concept of the present invention. Furthermore, even if the effects of the configuration of the present invention are not explicitly described and explained while the embodiments of the present invention are described above, it is natural that the effects that can be predicted by the configuration should also be recognized. [Explanation of symbols]

[0190] 10 cans 11 Side wall member 12 Bottom member 13 1st electrode terminal 14 Gasket 15 2nd electrode terminal 19 Insulator 20 Electrode assembly 21 1st electrode 22 2nd electrode 23 Metallic foil 24 Active material layer 25 Maintenance Department 26 Ignorance 27 Electrode tab (notched tab) 28 Separation membrane 31 First current collector (positive current collector) 312 1st terminal connection part 313 Ring Section 314 1st electrode connection part 32 Second current collecting plate 321 Inner ring part 322 holes 323 2nd electrode connection part 324 2nd terminal connection part 328 Bend section 40 Cap 41 Centripetal 43 2nd slope part 45 Receiving part 47 1st slope part 48 Curved part 49 Butt joint 70 Battery Pack 71 Housing 72 battery cells 80 vehicles W welded section

Claims

1. A battery cell including a can including a sidewall member extending in an axial direction, an electrode assembly accommodated inside the can, and a cap covering an open end provided at one axial end of the sidewall member, a terminal connection portion extending outward in the axial direction and contacting and electrically connecting to an inner circumferential surface of the side wall member is provided at a radially outer edge of a current collector plate connected to the electrode of the electrode assembly and disposed on the open end side; a welded portion formed by welding the inner peripheral surface of the side wall member and the outer peripheral surface of the cap, with at least a portion of the terminal connecting portion in the axial direction being interposed between the inner peripheral surface of the side wall member and the outer peripheral surface of the cap; Battery cell.

2. the current collecting plate includes an electrode connecting portion connected to an electrode of the electrode assembly and extending in a radial direction; the terminal connecting portion is disposed radially outward of the electrode connecting portion, The terminal connecting portion and the electrode connecting portion are connected to each other via a bending portion that is provided at a lower end of the terminal connecting portion and changes the extending direction of the current collecting plate. The battery cell of claim 1 .

3. The side wall member extends further outward in the axial direction than the terminal connecting portion of the current collector plate. The battery cell according to claim 1 or 2.

4. an inner diameter of an inner circumferential surface of a section of the side wall member that extends further outward in the axial direction than the terminal connecting portion of the current collector plate is larger than an inner diameter of the inner circumferential surface of the terminal connecting portion; The battery cell of claim 3 .

5. The outer peripheral surface of the cap is in contact with the inner peripheral surface of the terminal connecting portion. The battery cell according to claim 1 or 2.

6. The edge of the cap is provided with an abutment portion extending in the axial direction so that the outer peripheral surface of the abutment portion faces the inner peripheral surface of the side wall member in the radial direction. The battery cell of claim 5 .

7. The butt portion extends further outward in the axial direction than the terminal connecting portion of the current collector plate. The battery cell of claim 6 .

8. an outer diameter of an outer peripheral surface of a section of the butt portion that extends further axially outward than the terminal connecting portion of the current collector plate is smaller than the outer diameter of the outer peripheral surface of the terminal connecting portion; The battery cell of claim 6 .

9. The welded portion is formed by welding at least an axially outer edge of an inner peripheral surface of the side wall member, an axially outer edge of an outer peripheral surface of the butt portion, and an axially outer edge of the terminal connecting portion. The battery cell of claim 6 .

10. an axially inner end of the butt portion is connected to an axially inner convex curved surface portion, an inner end portion of the curved portion in the axial direction interferes with the current collector plate in the axial direction, thereby restricting the insertion depth of the cap into the open end portion; The battery cell of claim 6 .

11. a receiving portion extending flatly in the radial direction is provided on the cap radially inward of the curved surface portion, The curved surface portion and the receiving portion are connected via a first inclined portion that extends outward in the axial direction as it goes radially inward. The battery cell of claim 10.

12. The axially outer surface of the receiving portion protrudes further outward in the axial direction than the abutting portion and the side wall member. The battery cell of claim 11 .

13. a centripetal portion extending in a radial direction is provided on the cap radially inward of the receiving portion, The receiving portion and the centripetal portion are connected via a second inclined portion that extends inward in the axial direction as it goes radially inward. The battery cell of claim 11 .

14. The second inclined portion has a gentler inclination than the first inclined portion. The battery cell of claim 13 .

15. an axially outer edge of the terminal connecting portion is disposed axially further inward than an axially outer edge of the side wall member and an axially outer edge of the butt portion; The battery cell of claim 6 .

16. 3. The method for manufacturing a battery cell according to claim 1 or 2, inserting the current collecting plate into the can such that an outer circumferential surface of the terminal connecting portion of the current collecting plate contacts an inner circumferential surface of the side wall member; Inserting the cap into the can so that an outer circumferential surface of the cap contacts an inner circumferential surface of a terminal connection portion of a current collector plate inserted into the can; and irradiating a laser beam in an axial direction to a region where the outer peripheral surface of the side wall member and the inner peripheral surface of the can face each other to form a weld; A method for manufacturing a battery cell.

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