Battery cell

Abstract

The utility model relates to a battery cell. A battery cell includes a can in which an electrode assembly is housed, in which the can has a bottom member, a side wall member connected to the bottom member and extending upward therefrom in an axial direction, and a cap covering an open end of the can at an axial end opposite to the bottom member. The current collector plate is connected to an electrode tab of the electrode assembly near the open end. The current collector plate includes a central portion electrically connected to the electrode tab and a peripheral portion in electrical contact with a radially inner surface of the sidewall member of the can. The peripheral portion is also in contact with the lower side of the cover. A radially inner surface of the side wall member, a radially outer surface of the cover, and a peripheral portion of the current collector plate are all welded to each other.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority based on Korean Patent Application No. 10-2023-0059345 filed on May 8, 2023 and Korean Patent Application No. 10-2023-0135319 filed on October 11, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to the field of batteries, and particularly to a welding structure of a battery can, a current collector plate and a cover, and a battery cell applying the welding structure. Background Art

[0004] The process of manufacturing a battery cell having a cylindrical can includes deep drawing a metal sheet to form a circular bottom and a circular tubular sidewall member connected to the circular bottom, then housing an electrode assembly in the can, and then covering an open end of the sidewall member with a cap.

[0005] At the same time, a current collector plate that contacts and is electrically connected to at least one electrode connector of the electrode assembly is disposed at one of the two axial ends of the electrode assembly (i.e., at the axial end facing the open end). The current collector plate contacts and is electrically connected to the cover or sidewall member by welding the current collector plate to the cover or sidewall member.

[0006] In the process of welding the current collector plate to the cover or sidewall member, the current collector plate can be kept in close contact with the cover or sidewall member. To achieve this, a clamp that keeps the current collector plate in close contact with the cover or sidewall member may be required, and a mask that exposes the welding area may also be required.

[0007] In order to hold the collector plate on the cover or sidewall member by a mask or a clamp, a space for accommodating the mask or the mold may be provided in the tank. However, after removing the mask or the clamp, such a space will remain empty, resulting in a reduced utilization efficiency of the internal volume of the tank. This hinders the energy density per unit volume of the tank.

[0008] In addition, when completing the assembly of the cylindrical can, the process of connecting the current collector plate to the cover or sidewall member and the process of connecting the cover to the sidewall member are performed separately. This increases the man-hours involved in assembling the battery cell components, which reduces the production efficiency of the cylindrical battery cell and increases the production cost. Utility Model Content

[0009] In order to solve at least some of the above problems, the present disclosure provides a welding structure of a battery can, a current collector plate and a cover, and a battery cell to which the welding structure is applied, wherein an increased energy density per volume can be obtained without wasting or sacrificing the internal volume of the can (such as by omitting a separate welding mask or fixture in the process of welding the current collector plate to the can). Additionally or alternatively, the present disclosure may include integrating the process of welding the current collector plate to the can and the process of welding the cover to the sidewall member into a single welding process, which can advantageously improve production efficiency and reduce production costs.

[0010] In addition, or alternatively, the tank, collector plate and cover can be used as a mask and fixture according to the present disclosure, which can beneficially increase the stability of the process. The shape and / or engagement relationship between the tank, collector plate and cover of the present disclosure can also beneficially increase the effectiveness and / or durability of welding, and / or can increase process stability.

[0011] However, the technical problems solved by the present disclosure are not limited to the above-mentioned purposes, but other purposes and advantages not described in the present disclosure can be understood through the following description and examples.

[0012] According to one embodiment of the present disclosure, a battery cell is provided. The battery cell may include a can, an electrode assembly, a current collector plate and a cover. The can may have a sidewall member defining an internal volume and define an opening to the internal volume at a first end of the can along a central longitudinal axis. The electrode assembly may be accommodated in the internal volume of the can. The cover may cover the opening of the can, thereby closing the internal volume. The current collector plate may be electrically connected to the electrode assembly. In addition, the current collector plate may include a central portion and a peripheral portion, wherein the peripheral portion is positioned around the central portion and the peripheral portion is spaced farther from the central longitudinal axis than the central portion. The central portion may be electrically connected to an electrode connector of the electrode assembly. The peripheral portion may contact the radial inner surface of the sidewall member so as to be electrically connected to the can, and the peripheral portion may contact the lower side of the cover, wherein the lower side of the cover faces the internal volume in an axial direction extending parallel to the central longitudinal axis. The radial inner surface of the sidewall member, the radial outer surface of the cover and the peripheral portion of the current collector plate are preferably welded to each other.

[0013] According to some embodiments of the battery cell, the radial inner surface of the sidewall member may include a transverse step extending transversely to the central longitudinal axis. The transverse step may cause the first inner surface of the sidewall member positioned on the first side of the transverse step in the axial direction to have a first diameter, and the second inner surface of the sidewall member positioned on the second side of the transverse step in the axial direction to have a second diameter, wherein the second side of the transverse step is closer to the opening of the can than the first side. In addition, the second diameter of the second side may be greater than the first diameter of the first side. In addition, the radial outer surface of the cover and the peripheral portion of the collector plate may contact the second inner surface.

[0014] According to some of the above-mentioned schemes of the battery cell, the outer diameter of the peripheral portion of the collector plate may be greater than the first diameter of the first inner surface of the side wall member of the can. According to some other schemes of the above-mentioned schemes of the battery cell, the peripheral portion of the collector plate may be in contact with the transverse step. According to some other schemes of the above-mentioned schemes of the battery cell, the transverse step may be defined by an inclined surface extending from a first diameter of the first inner surface to a second diameter of the second inner surface. According to some other schemes of the above-mentioned schemes of the battery cell, the first thickness of the cover in the axial direction along the radial outer surface is greater than the second thickness of the side wall member in the radial direction along the second inner surface, wherein the radial direction is perpendicular to the central longitudinal axis. According to some of these schemes, the first thickness may be between one and two times the second thickness.

[0015] According to some aspects of the battery cell, the diameter of the radially outer surface of the cover may be smaller than the diameter of the adjacent portion of the radially inner surface of the sidewall member. In addition, the welding area may extend from the adjacent portion of the radially inner surface of the sidewall member to the radially outer surface of the cover.

[0016] According to some aspects of the battery cell, the cover may include an annular region extending along the radial outer surface. In addition, the thickness of the annular region of the cover in the axial direction may be less than the thickness of the central region of the cover, the central region being located along the central longitudinal axis. According to some of these aspects, an inclined surface along the underside of the cover may connect the annular region and the central region. According to other aspects, the inclined surface may contact the current collector plate.

[0017] According to some aspects of the battery cell, the current collector plate may include a step in an axial direction between the central portion and the peripheral portion such that the peripheral portion is offset relative to the central portion toward the opening of the can.

[0018] According to some embodiments of the battery cell, the longitudinal dimension of the central portion of the current collector plate may extend transversely to the axial direction, and the longitudinal dimension of the peripheral portion of the current collector plate may extend parallel to the axial direction. In this way, the peripheral portion may extend along the radial inner surface of the side wall member of the can to a terminal end of the peripheral portion adjacent to the lower side of the cover.

[0019] According to another embodiment of the present disclosure, a method for manufacturing a battery cell is provided. The method may include the following steps: positioning a cover and a current collector plate in an assembly position stacked on each other within the opening of the can. In such an assembly position, the current collector plate may be electrically connected to an electrode assembly housed within the internal volume of the can. In addition, in such an assembly position, a peripheral portion of the current collector plate may contact a radial inner surface of a side wall member of the can surrounding the opening. In addition, in such an assembly position, the cover may be positioned above the current collector plate along the central longitudinal axis of the can, so that the cover is further away from the electrode assembly than the current collector plate. Preferably, the method further includes the step of welding the radial inner surface of the side wall member, the radial outer surface of the cover, and the peripheral portion of the current collector plate to each other.

[0020] According to some aspects of the method, the step of positioning the cover and the current collector plate in an assembled position may include the step of contacting a peripheral portion of the current collector plate with a transverse step defined on a radially inner surface of a sidewall member of the can.

[0021] According to some aspects of the method, the step of positioning the cover and the current collector plate in an assembled position may include the step of contacting an inclined surface located along an underside of the cover with an annular portion of the current collector plate extending along the peripheral portion.

[0022] According to some aspects of the method, the step of welding the radial inner surface of the side wall member of the can may include the step of melting a material of an extension of the side wall member that protrudes above the cover in an axial direction extending parallel to the central longitudinal axis. As a result, the material of the extension may flow between the radial inner surface of the side wall member and the radial outer surface of the cover, thereby joining the side wall member and the cover together.

[0023] According to some aspects of the method, the step of welding the radial inner surface of the sidewall member may include the following steps: performing tack welding at a plurality of discrete locations spaced apart from one another along the sidewall member in a circumferential direction about the central longitudinal axis. The method may also include the following steps: performing continuous welding along the sidewall member to form a weld substantially surrounding the cover in a circumferential direction.

[0024] According to some aspects of the method, the step of positioning the cover and the current collector plate in the assembly position may include the step of inserting the electrode assembly in combination with the current collector plate into the interior volume of the can. According to further aspects of some of these aspects, the step of positioning the cover and the current collector plate in the assembly position may further include the step of inserting the cover into the opening of the can and contacting the current collector plate. In addition, inserting the cover into the opening and contacting the current collector plate may occur after inserting the electrode assembly in combination with the current collector plate into the can. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1is a perspective view of a cylindrical battery cell according to one aspect of the present disclosure.

[0026] Figure 2 The electrode assembly is wound and housed in Figure 1 An exploded perspective view of the tank before it was placed in the tank.

[0027] Figure 3 yes Figure 2 A perspective view of an electrode assembly in a stacked state before winding.

[0028] Figure 4 By winding Figure 3 A perspective view of a cylindrical jellyroll-type electrode assembly assembled by stacking a plurality of layers.

[0029] Figure 5 is to show the bond to Figure 4 A perspective view of a first current collector plate of an electrode tap of a first electrode of an electrode assembly.

[0030] Figure 6 is shown in conjunction with Figure 4 A perspective view of a second current collector plate of an electrode tap of a second electrode of an electrode assembly.

[0031] Figure 7 is a side sectional view showing a process of positioning an electrode assembly in which a first current collector plate and a second current collector plate are combined into a can.

[0032] Figure 8 is a side sectional view illustrating a process of combining a first current collector plate with a first electrode terminal of an electrode assembly accommodated in a can.

[0033] Fig. 9 is a side cross-sectional view showing a process of positioning a cap to cover an open end of a can having an electrode assembly accommodated therein.

[0034] Fig.10 is an enlarged side cross-sectional view of the open end of the can covered with a lid.

[0035] Fig.11 yes Fig.10 An enlarged view of the area where the side wall members, current collector plate and cover are welded together.

[0036] Fig.12 It shows the welding process Fig.11 map of the area.

[0037] Fig.13 After welding, Fig.11 The area corresponds to a photograph of a cut cross section of a battery cell.

[0038] Fig.14 is an alternative to the present disclosure Fig.11 Magnified view of the area shown in .

[0039] Fig.15A , Fig. 15B and Fig. 15C are a plurality of graphs showing the location and magnitude of stress concentrations based on different weld lengths along the peripheral bonding surface of the cover.

[0040] Fig.16 is a flow chart showing a manufacturing process of a battery cell according to the present disclosure.

[0041] Fig.17 is a perspective view of a battery pack including a plurality of battery cells according to various aspects of the present disclosure.

[0042] Fig.18 Is equipped with Fig.17 Schematic diagram of the battery pack of a car. DETAILED DESCRIPTION

[0043] 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 will be able to implement the technical ideas of the present disclosure. When describing the present disclosure, when it is determined that the detailed description of the prior art related to the present disclosure unnecessarily obscures the main points of the present disclosure, its detailed description will be omitted. Hereinafter, each scheme of the present disclosure will be described in detail with reference to the accompanying drawings. In the accompanying drawings, the same reference numerals are used to represent the same or similar parts.

[0044] Although "first", "second", etc. are used to describe various elements, these elements are not limited by these terms. Instead, such terms are only used to distinguish one element from another element, and unless otherwise specifically stated, a component identified as a first element may also be a second element, and vice versa.

[0045] Throughout the specification, unless otherwise specified, each element may be in the singular or in the plural.

[0046] Hereinafter, “arranging an element at the upper (or lower) part of a component” or “setting an element at the top (or bottom) of a component” means not only arranging the element to be in contact with the upper surface (or lower surface) of the component, but also arranging the element above the upper surface (or below the lower surface) with another element interposed therebetween.

[0047] In addition, when an element is described as being “connected to,” “coupled to,” or “contacting” a component, it should be understood that the element may be directly connected to, directly coupled to, or directly contact the component, or the element may be connected to, coupled to, or contact the component with one or more other elements interposed therebetween.

[0048] Unless the context clearly dictates otherwise, expressions in the singular form herein include expressions in the plural form.

[0049] Throughout the specification, unless specifically stated otherwise, "A and / or B" means A, B, or A and B, and "C to D" include endpoints and all intervening values.

[0050] In the description of the implementation scheme, the "axial direction" refers to the direction in which the central longitudinal axis of the winding center constituting the core-type electrode assembly extends (i.e., the direction parallel to the central longitudinal axis), while the "radial direction" refers to the direction toward (centripetal) or away from (eccentric) the axis, and the "circumferential direction" refers to the direction around the axis.

[0051] In the following, reference will be made to Figures 1 to 13 One embodiment of a battery cell to which the welding structure of the present disclosure is applied is described in detail.

[0052] The battery cell of this aspect of the present disclosure may be, for example, a cylindrical battery cell having a shape factor ratio (defined as the diameter of a cylindrical battery cell divided by its height, ie, the ratio of diameter Φ to height H) greater than about 0.4.

[0053] The shape factor refers to a value indicating the diameter and height of a cylindrical battery cell. A 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 value indicating the shape factor, the first two digits indicate the diameter of the cell, the next two digits represent the height of the cell, and the last digit 0 indicates that the cross section of the cell is circular.

[0054] The battery cell may be a substantially cylindrical cell having a diameter of approximately 46 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0055] A battery cell according to another aspect may be a nearly cylindrical cell having a diameter of about 48 mm, a height of about 75 mm, and a form factor ratio of 0.640.

[0056] A battery cell according to yet another aspect may be a nearly cylindrical cell having a diameter of about 48 mm, a height of about 110 mm, and a form factor ratio of 0.418.

[0057] A battery cell according to yet another aspect may be a nearly cylindrical cell having a diameter of about 48 mm, a height of about 80 mm, and a form factor ratio of 0.600.

[0058] A battery cell according to another aspect may be a nearly cylindrical cell having a diameter of about 46 mm, a height of about 80 mm, and a form factor ratio of 0.575.

[0059] The present disclosure can be applied in the context of battery cells having a shape factor ratio of about 0.4 or less, such as 18650 cells, 21700 cells, etc. For 18650 cells, the diameter is about 18 mm, the height is about 65 mm, and the shape factor ratio is 0.277. For 21700 cells, the diameter is about 21 mm, the height is about 70 mm, and the shape factor ratio is 0.300.

[0060] The battery cell of the present disclosure includes an electrode assembly 20 , current collector plates 31 and 32 electrically connected to the electrode assembly 20 , and a can 10 accommodating the electrode assembly 20 and the current collector plates 31 , 32 therein.

[0061] The can 10 includes a bottom member 12 , a side wall member 11 connected to the bottom member 12 and extending in the axial direction, and a cover 16 covering an open end provided at one axial end of the side wall member 11 .

[0062] The bottom member 12 may have a disc shape having a hole provided at the center thereof, and the sidewall member 11 may have a circular tube shape defining the inner volume of the can 10 .

[0063] The bottom member 12 and the side wall member 11 may be manufactured by deep drawing a metal sheet having a nickel-plated steel surface (although the material is not limited thereto), and then trimming the side wall member 11 with a punch while holding the front end of the side wall member with a blank holder.

[0064] The first electrode terminal 13 may be fitted into the hole and coupled to the hole. The first electrode terminal 13 may be riveted and fixed to the bottom member 12 with the gasket 14 interposed therebetween. Specifically, 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, thereby preventing electrolyte leakage and electrically insulating the first electrode terminal 13 from the bottom member 12.

[0065] However, the connection method between the first electrode terminal 13 and the bottom member 12 is not limited thereto. For example, if the resulting structure is capable of forming a seal between the first electrode terminal 13 and the bottom member 12 and also electrically insulating the first electrode terminal from the bottom member 12, various other fixing methods such as a bolt and nut connection method, a glass sealing method, and a chrome coating and PP MAH (maleic anhydride grafted polypropylene or maleated polypropylene) thermal bonding method may be used.

[0066] The first electrode terminal 13 may have a first polarity, and the can 10 may have a second polarity. That is, the bottom member 12 of the can 10, the side wall member 11 connected thereto, and the cover 16 (described below) connected to the side wall member 11 may all have a second polarity.

[0067] Therefore, the battery cell may have both the first electrode terminal 13 and the second electrode terminal 15, which are disposed at the axial end where the bottom member 12 is disposed (i.e., disposed at the closed end of the can 10). As a result, the battery cell may have a bus bar connected to the first electrode terminal 13 and another bus bar connected to the second electrode terminal 15, wherein both bus bars are located at the top of the battery cell.

[0068] In one example, the first electrode terminal 13 may be a cathode terminal and the second electrode terminal 15 may be an anode terminal, although they may be reversed in different examples.

[0069] The electrode assembly 20 is accommodated in the inner volume of the can 10. Figure 2 As shown, the electrode assembly 20 is manufactured by preparing a first electrode 21, a second electrode 22, and a separator 28 extending in a length direction with a predetermined width; Figure 3 As shown, a stacked body is formed by sequentially stacking a first electrode 21, a separator 28, a second electrode 22, and a separator 28; Figure 4 As shown, the laminate is wound into a shape having a winding core wound around a mandrel.

[0070] The first electrode 21 may be a positive electrode, and the second electrode 22 may be a negative electrode. However, the first electrode 21 and the second electrode 22 may be opposite.

[0071] The first electrode 21 and the second electrode 22 are manufactured in the form of sheets. The electrode sheet is manufactured by applying an active material layer 24 to the surface of a metal foil 23. The electrode sheet includes a coated area 25 coated with the active material layer 24 and an uncoated area 26 not coated with the active material layer. The positive electrode sheet is provided with the uncoated area 26 on one side in the width direction, and the negative electrode sheet is provided with the non-coated area 26 on the other side in the width direction.

[0072] The first electrode 21 and the second electrode 22 are arranged in the stack so that their uncoated regions 26 are exposed or protruded from the stack in the width direction, wherein the uncoated region 26 of the first electrode 21 protrudes at one axial end of the wound core, and the uncoated region 26 of the second electrode 22 protrudes at the opposite axial end of the core. The uncoated region 26 itself functions as at least one electrode tab 27.

[0073] Notches may be formed at predetermined intervals along the uncoated region 26 to define notched tabs 27 .

[0074] Each of the notched joints 27 can be formed in the form of a flag. In the illustrated embodiment, the notched joints 27 have the shape of an equilateral trapezoid. However, the notched joints 27 can have various shapes, such as a semicircle, a semi-ellipse, a triangle, a rectangle, a parallelogram, etc. In addition, in the illustrated embodiment, the notched joints 27 each have the same width along the length direction of the electrode. However, in another embodiment, the width of the notched joints along the length direction can gradually widen from the core side to the peripheral side.

[0075] In addition, if Figure 2 and Figure 3 As shown, the height of the notched joint 27 gradually increases from the core side to the peripheral side. However, in an alternative, the height of the notched joint may be constant or may gradually decrease.

[0076] In addition, according to this scheme, at both opposite ends of the first electrode 21 and the second electrode 22 in the length direction, the notched joint 27 may be removed from the uncoated region 26 or may not exist. However, in some schemes, when the electrode assembly 20 is wound into a jellyroll configuration, the notched joints may not be removed from either end, or they may be removed only from the uncoated region at the radially inner end or the radially outer end.

[0077] like Figure 4 As shown, in the jellyroll type electrode assembly 20, the notched joint 27 can be bent and flattened in the radial direction. That is, the notched joint 27 can be bent inward or outward in the radial direction. Although, according to various embodiments of the present disclosure, as shown in the figure, the notched joint 27 is bent inward in the radial direction.

[0078] The notched tabs 27 may be bent one by one in the process of winding the laminate to form the jellyroll-type electrode assembly 20. Alternatively, the notched tabs 27 may be formed by bending the laminate at one time after it has been wound to form the jellyroll-type electrode assembly.

[0079] The notched joints 27 of the first electrode 21 and the notched joints 27 of the second electrode 22 that are bent in the radial direction and overlap each other may be provided with a plane substantially perpendicular to the axial direction at each of opposite axial ends of the electrode assembly 20 .

[0080] like Figure 5 and Figure 6 As shown, the first current collector plate 31 and the second current collector plate may be coupled to a substantially flat surface provided by the curved notched joints 27 exposed at both axial ends of the electrode assembly 20 .

[0081] In one embodiment, the first current collector plate 31 is a positive current collector plate, and the second current collector plate 32 is a negative current collector plate. The first current collector plate 31 can be made of aluminum, and the second current collector plate 32 can be made of copper. The current collector plates 31 and 32 can be made by stamping, trimming, perforating and / or bending metal sheets.

[0082] Reference Figure 5 The first current collector plate 31 includes a terminal connection portion 312 extending from the center in the radial direction, an annular portion 313 connecting the radial outer ends of the terminal connection portion 312 and extending in the circumferential direction, and an electrode connection portion 314 extending radially inward from the annular portion 313 without being connected to the terminal connection portion 312. The center of the terminal connection portion 312 covers at least a portion of the core hollow portion along the central longitudinal axis of the electrode assembly 20.

[0083] Prior to inserting the electrode assembly 20 into the can 10, the electrode connection portion 314 is joined to the notched tab 27 of the first electrode 21 of the electrode assembly 20 using a method such as laser welding. The weld line of the laser may extend radially.

[0084] Reference Figure 6 , the second current collector plate 32 defines a hole 322 corresponding to the core hollow portion of the electrode assembly 20. The second current collector plate 32 includes an inner ring portion 321 surrounding the core hollow portion and an electrode joint connection portion 323 extending radially from the inner ring portion 321. The electrode joint connection portion 323 may be in the form of a plurality of spokes extending radially outward from the inner ring portion, wherein one or more of the spokes have a radially outer end connected to a peripheral portion of the current collector plate 32 referred to as a can connection portion 324. In addition, one or more spokes of the electrode joint connection portion 323 may have a radially outer end that does not reach the can connection portion 324. The can connection portion 324 has an outer ring shape surrounding the electrode joint connection portion 323, and the can connection portion 324 may include a step away from the electrode assembly 20 in the axial direction, so that at least the outermost periphery of the can connection portion 324 is spaced farther from the electrode assembly 20 than other portions of the can connection portion 324 including the electrode joint connection portion 323 and the inner ring portion 321.

[0085] Before the electrode assembly 20 is inserted into the can 10, the electrode tab connection portion 323 is joined to the notched tab 27 of the second electrode 22 of the electrode assembly 20 by laser welding or the like. The welding line of the laser may extend radially.

[0086] like Figure 7 and Figure 8 As shown, the electrode assembly 20 is accommodated in the can 10, and the first current collector plate 31 is aligned to face the bottom member 12 of the can 10. The insulator 19 is interposed between the first current collector plate 31 and the bottom member 12 of the can 10 to electrically insulate the first current collector plate 31 from the bottom member 12.

[0087] The terminal connection portion 312 of the first current collector plate 31 is bonded to the first electrode terminal 13 by resistance welding, ultrasonic welding, laser welding, etc. The welding device for welding the first current collector plate 31 and the first electrode terminal 13 may perform welding by approaching the inner side of the center of the terminal connection portion 312 of the first current collector plate 310 (i.e., the side of the terminal connection portion 312 facing the electrode assembly 20). Specifically, as Figure 8 As shown, the welding device can enter the position of the first current collector plate 31 from the open end of the can 10 through the core hollow portion of the electrode assembly 20. As an alternative to the above-mentioned welding method, the first current collector plate 31 and the first electrode terminal 13 can be joined to each other by brazing or welding. That is, various joining methods can be used as long as the first current collector plate 31 and the first electrode terminal 13 are both fixed to each other and electrically connected to each other.

[0088] In a case where the electrode assembly 20 is accommodated inside the can 10 , the electrode tab 27 of the second electrode 22 and the second current collector plate 32 will be arranged to face the open end of the sidewall member 11 .

[0089] After the first current collector plate 31 and the first electrode terminal 13 are combined, an electrolyte solution may be injected into the can 10. After the electrolyte solution is injected, the open end of the sidewall member 11 may be covered and closed by the cap 16, as shown in FIG. Fig. 9 shown.

[0090] The welding method of the present disclosure may also be used in conjunction with a method in which the cover 16 is first positioned to cover and close the open end of the side wall member 11, after which an electrolyte solution may be injected through the liquid injection port of the cover 16, which is then closed.

[0091] like Fig.10 As shown, the edge of the lid 16 is bonded to the edge of the side wall member 11 by seam welding using a laser, so that the can 10 can be sealed thereby.

[0092] Reference Fig.10 and Fig.11, the inner diameter expansion portion 113 may be provided at the open end of the sidewall member 11. The inner diameter expansion portion 113 may be in the form of a transverse step extending transversely to the central longitudinal axis and positioned along the radial inner surface of the sidewall member 11. Therefore, the radial inner surface of the sidewall member 11 may include a first inner surface 111 and a second inner surface 115, the first inner surface being axially positioned below the inner diameter expansion portion 113 (i.e., further away than the opening at the open end of the sidewall member 11), and the second inner surface being axially positioned above the inner diameter expansion portion 113 (i.e., closer than the opening at the open end of the sidewall member 11). The second inner surface 115 may have a larger inner diameter than the first inner surface 111. Therefore, the second thickness t2 of the sidewall member 11 measured in the radial direction at the portion where the second inner surface 115 is located is less than the first thickness (total thickness) t1 of the sidewall member 11 at the portion where the first inner surface 111 is located.

[0093] The tank connection portion 324 provided at the edge of the second current collector plate 32 and electrically connected to the tank 10 includes a first portion in contact with the second inner surface 115 of the sidewall member 11. In the first portion, a peripheral contact surface 325 is provided that faces and contacts the second inner surface 115 of the sidewall member 11 in the radial direction.

[0094] The tank connection portion 324 includes a second portion that contacts the cover 16. In the second portion, a cover contact surface 326 that faces and contacts the inner surface of the cover 16 in the axial direction (ie, the lower side of the cover 16) is provided.

[0095] The outer diameter of the outer peripheral contact surface 325 of the tank connection portion 324 is set to be larger than the inner diameter of the first inner surface 111. Therefore, the tank connection portion 324 includes a third portion that contacts the inner diameter expansion portion 113. The third portion is positioned on the opposite side of the cover contact surface 326 in the axial direction. The third portion contacts the inner diameter expansion portion 113, thereby limiting the depth of insertion of the second current collector plate 32 into the tank 10.

[0096] The second current collector plate 32 also includes a first bend 327 and a second bend 328, thereby defining a step in the axial direction. The first bend 327 is where the second current collector plate 32 extending outward in the radial direction is bent upward in the axial direction. The second bend 328 is where the upwardly bent portion of the second current collector plate 32 is bent backward in the radial direction. As a result of the axial step between the first bend 327 and the second bend 328, the peripheral portion (or tank connection portion 324) of the current collector plate 32 is offset in the axial direction toward the open end of the tank 10 relative to the central portion of the current collector plate 32. The tank connection portion 324 is connected to the electrode joint connection portion 323 through the first bend 327 and the second bend 328 and through the above-mentioned inner ring portion 321. The tank connection portion 324 is connected to the radial outer side of the second bend 328 and extends outward in the radial direction from the second bend 328, thereby providing the cover contact surface 326 of the second current collector plate 32.

[0097] The material of the second current collector plate 32 is desirably softer than that of the sidewall member 11, and therefore, the first bent portion 327 and the second bent portion 328 are elastically deformed in the process of inserting the second current collector plate 32 into the open end of the sidewall member 11. Therefore, when the outer diameter of the peripheral contact surface 325 is set to be slightly larger than the inner diameter of the second inner surface 115, the peripheral contact surface 325 is press-fitted into the second inner surface 115.

[0098] The cover 1616 includes, in order from the center to the outside in the radial direction: a cover body 160, a thickness reduction portion 161 (a portion of the cover where the thickness changes), and a coupling portion 17. That is, the cover body 160 is centered on the central area of ​​the cover 16, and the thickness reduction portion 161 is provided around the outside of the cover body 160 in the radial direction. The coupling portion 17 is positioned along the radial outside of the thickness reduction portion 161 to define an annular region of the cover 16 having a reduced thickness relative to the cover body 160. That is, the third thickness t3 of the coupling portion 17 measured in the axial direction is smaller than the fourth thickness t4 of the cover body 160 measured in the axial direction.

[0099] An outer peripheral bonding surface 171 facing the second inner surface 115 of the side wall member 11 in the radial direction is provided along the radial outer surface of the cover 16, particularly along the radial outer surface of the bonding portion 17. In addition, the lower side of the cover 16 along the bonding portion 17 includes a collector plate contact surface 173 facing downward in the axial direction to contact the cover contact surface 326 of the tank connecting portion 324 of the second collector plate 32.

[0100] The position of the reduced thickness portion 161 is selected so that at least a portion of the reduced thickness portion 161 contacts the second current collector plate 32. In the process of inserting the cover 16 into the open end of the sidewall member 11, when the reduced thickness portion 161 of the cover 16 contacts the second current collector plate 32, such contact beneficially achieves the effect of aligning the center of the cover 16 relative to the second current collector plate 32 and the central longitudinal axis. In the illustrated scheme, the alignment effect can be achieved by placing the reduced thickness portion 161 at a position corresponding to the position where the second bend 328 of the second current collector plate 32 is formed in the radial direction. In order to improve the alignment effect, the reduced thickness portion 161 is desirably in the form of an inclined surface that extends upward in the axial direction as it approaches the outside in the radial direction. In addition, in order to improve the alignment effect, an inclined surface is desirably provided on the second current collector plate 32 by the surface shape of the second bend 328 of the second current collector plate 32.

[0101] The outer peripheral bonding surface 171 of the cover 16 and the outer peripheral contact surface 325 of the second current collector plate 32 are each in contact with the second inner surface 115 of the side wall member 11 in the radial direction. In addition, in the axial direction, at least a portion of the lower side of the second current collector plate 32 along the peripheral portion thereof is in contact with the inner diameter expansion portion 113 of the side wall member 11. The cover contact surface 326 provided on the upper side of the second current collector plate 32 is in contact with the current collector plate contact surface 173 provided on the lower side of the bonding portion 17 of the cover 16.

[0102] With the second current collector plate 32 and the cover 16 inserted, an overhang 117 in the form of an extension of the side wall member 11 may be provided at the open end, the overhang 117 protruding upward in the axial direction above the cover 16 .

[0103] like Fig.11 As shown, the first height h1 of the area extending axially upward from the inner diameter expansion portion 113 is greater than the sum of the third thickness t3 of the coupling portion 17 of the cover 16 and the fifth thickness t5 of the tank connection portion 324 of the second current collector plate 32. That is, the second height h2 of the overhang portion 117 may be a length obtained by subtracting the third thickness t3 and the fifth thickness t5 from the first height h1. In one example, the first height h1 may be 1 mm, the second height h2 may be 0.2 mm, the third thickness may be 0.5 mm, and the fifth thickness t5 may be 0.3 mm.

[0104] The welding portion W is formed along the contact area between the side wall member 11, the second current collector plate 32 and the cover 16 (specifically, the area where the second inner surface 115 of the side wall member 11, the peripheral bonding surface 171 of the cover 16 and the tank connection portion 324 of the second current collector plate 32 are welded together).

[0105] The welded portion W may be formed substantially or completely along the cover 16 in the circumferential direction. Therefore, the welded portion W may also function as a sealant S that seals the contact area between the can 10 and the cover 16.

[0106] However, in another embodiment, the welded portion W may be formed only in discrete portions spaced apart from each other in the circumferential direction. For example, the welded portion W may constitute only a portion of the contact area of ​​the seal portion S between the sealed can 10 and the cover 16 .

[0107] The welding portion W may be formed by laser irradiated to weld the contact area between the can 10 and the cover 16 and the contact area between the can connection portion 324 of the second current collector plate 32 and the can 10 in the circumferential direction.

[0108] The sealing portion S may also be formed by laser welding which is continuously irradiated onto the contact area of ​​the can 10 and the cover 16 in the circumferential direction.

[0109] The welding portion W may be formed in a preliminary welding process or in a subsequent main welding process. The sealing portion S may be formed in the main welding process. In some embodiments, the welding portion W and the sealing portion S may be formed together in the main welding process.

[0110] The illustrated scheme illustrates a structure in which the contact area between the can 10 and the cover 16 and the contact area between the can 10 and the second current collector plate 32 are welded together by continuously irradiating the laser in the circumferential direction in the main welding process while keeping the energy density and scanning speed of the laser constant. As a result, a welded portion W and a sealed portion S are formed along the entirety of the side wall member 11 in the circumferential direction.

[0111] However, instead, as part of the main welding process, an alternative may include continuously irradiating the contact area of ​​the tank 10 and the cover 16 with a laser in the circumferential direction. In addition, during this process, the tank connection portion 324 of the second current collector plate 32 may also be welded to the tank 10 by increasing the energy density of the laser or reducing the scanning speed only in certain discrete portions in the circumferential direction, so that the laser further penetrates downward to form a weld portion W along these discrete portions, while the seal portion S is formed at least substantially along the entire sidewall member in the circumferential direction. The resulting discrete portions where the weld portion W is formed between the second current collector plate 32 and the tank 10 are similar to a "position weld" that fixes the two components together, while the continuous seal portion S forms a seal substantially along the entire externally exposed contact area between the tank 10 and the cover 16. In fact, similar to positioning welding, the welding method may include: first forming a plurality of discrete weld portions W between the second current collector plate 32 and the can 10 and between the cover 16 and the can 10 (e.g., by using a slower speed and / or higher energy laser irradiation at discrete positions in the circumferential direction), and then continuously performing laser irradiation along the entire exposed connection between the can 10 and the cover 16. Advantageously, the method may utilize discrete welds to at least temporarily fix the position of the second current collector plate 32 and the cover 16 relative to the can 10 while performing a subsequent sealing process by forming a continuous seal S.

[0112] As shown in the drawings, upper axial ends of the radially inner surface of the side wall member 11 and the outer peripheral joint surface 171 of the cover 16 , which are in contact with each other in the radial direction, are exposed along the outside of the battery cell.

[0113] The welded portion W is formed by laser irradiated from outside the battery cell in the axial direction, and is oriented toward the axial ends of the second inner surface 115 of the side wall member 11 and the outer peripheral joint surface 171 of the cover 16 .

[0114] Since the outer peripheral contact surface 325 of the second current collector plate 32 is axially disposed below the cover 16 and in contact with the radial inner surface of the side wall member 11, it is possible to prevent the laser from being irradiated into the inner volume of the tank through any gap that may exist between the side wall member and the cover 16. In addition, the inner diameter expansion portion 113 of the side wall member 11 also prevents the laser from being irradiated and penetrating the gap between the side wall member 11 and the cover 16 or the gap between the side wall member 11 and the second current collector plate 32.

[0115] The second current collector plate 32 may be made of a material having a higher thermal conductivity than the sidewall member 11. In addition, the second current collector plate 32 is in contact with the sidewall member 11. Therefore, when welding heat generated by the laser in the sidewall member 11 is conducted in the axial direction of the sidewall member 11, the welding heat is dispersed to and passes through the top of the electrode assembly 20 through the second current collector plate 32, so that damage to the separator caused by the welding heat can be prevented.

[0116] The second current collector plate 32 is also in contact with the cover 16. Therefore, heat generated in the cover 16 by laser welding is dispersed and transferred through the second current collector plate 32. As a result, when the contact area between the cover 16 and the sidewall member 11 is heated by laser, the sidewall member 11 may be heated first and then melted.

[0117] Therefore, when the side wall member 11 is too thin, the side wall member 11 may melt before the cover 16, and welding may not be performed smoothly. Therefore, the second thickness t2 of the side wall member 11 is preferably 0.25 mm or more. For example, the second thickness t2 may be 0.35 mm.

[0118] It is also important that the cover 16 has sufficient strength to withstand the expected increase in internal pressure within the can 10. When the cover 16 is too thin, too much bulging may occur, in which the cover 16 expands into a spherical surface profile under the high internal pressure within the can 10, thereby deteriorating the durability of the battery cell. In order to resist such bulging deformation, it is important that the cover 16 has a certain thickness. On the other hand, when the thickness of the cover 16 is too thick relative to the side wall member 11, only the side wall member 11 may initially melt during the laser welding process, thereby greatly weakening the welding process. In addition, as the thickness of the cover 16 increases, the axial length of the peripheral bonding surface 171 of the cover 16 that can be welded also increases.

[0119] Fig.15A , Fig. 15B and Fig. 15C The stress analysis results when the internal pressure in the tank 10 increases in three cases are shown. Specifically, Fig.15A The case (a) in FIG. 1 involves welding the outer peripheral joint surface 171 of the cover 16 along the entire outer peripheral joint surface 171 of the cover 16 in the axial direction to form the sealing portion S and / or the welding portion W. Fig. 15B In case (b), the top 75% of the outer peripheral bonding surface 171 of the cover 16 in the axial direction thereof is welded to form the sealing portion S and / or the welding portion W. Finally, in Fig. 15C In case (c), the top 25% in the axial direction is welded to the outer peripheral bonding surface 171 of the cover 16 to form the sealing portion S and / or the welding portion W. Fig.15A , Fig. 15B and Fig. 15C It can be confirmed that when the outer peripheral bonding surface 171 of the cover 16 is not welded along the entire axial direction thereof, a weak portion exists in the welding area of ​​the side wall member 11 and the cover 16 .

[0120] The illustrated solution relates to a structure in which the third thickness t3 of the bonding portion 17 welded to the side wall member 11 is different from the fourth thickness t4 of the cover body 160. The thicker the fourth thickness t4 is, the higher the resistance against bulging is, but the internal space of the can occupied by it also increases. In order to increase the resistance to bulging while minimizing space occupation and weight, the fourth thickness t4 is preferably as small as possible within the range of the required bulging resistance.

[0121] As a result, the fourth thickness t4 of the cover body 160, which occupies most of the cover 16, is desirably greater than the third thickness t3, so as to minimize the deformation of the cover 16 due to the internal pressure in the tank 10, while also minimizing the thickness of the welded portion along the axial dimension, so as to ensure that the seal portion S and / or the welded portion W are formed along the entire axial dimension of the peripheral bonding surface 171, thereby increasing the strength of the cover 16 itself and the bonding strength of the cover 16 with the side wall member 11. The ratio of the third thickness t3 to the fourth thickness t4 is preferably 0.4 to 0.8, more preferably 0.5 to 0.75. When the ratio is less than this range, the cover body 160 becomes too thick without increasing the bulge resistance and / or the strength of the welded portion becomes insufficient. When the ratio is greater than this range, the bulge resistance of the cover body 160 becomes insufficient and / or the peripheral bonding surface 171 of the cover 16 becomes difficult to weld along its entire axial direction.

[0122] According to the illustrated solution, the reduced thickness portion 161 can be positioned as close as possible to the welding area in the radial direction so that the maximum area of ​​the cover body 160 that resists bulging can be obtained. In addition, by selecting the position of the reduced thickness portion 161, a guiding function for aligning the center of the cover 16 while contacting the second collector plate 32 can also be provided.

[0123] The third thickness t3 of the joint portion 17 of the cover 16 may be set to be greater than the second thickness t2 of the side wall member 11. The third thickness t3 may be between one and two times the second thickness t2. For example, when the second thickness t2 is 0.35 mm, the third thickness t3 may be 0.5 mm or in the range of 0.5 mm to 0.7 mm.

[0124] When the third thickness t3 is greater than twice the second thickness t2, there is a risk that the side wall member 11 may be excessively melted before the cover 16 is melted during the process of forming the seal portion and / or the weld portion. In addition, when the third thickness t3 is greater than twice the second thickness t2, there is a risk that the seal portion and / or the weld portion will not be formed along the entire peripheral bonding surface 171 of the cover 16 in the axial direction.

[0125] When the third thickness t3 is less than the second thickness t2 (that is, when the second thickness t2 is greater than the third thickness t3), it may be difficult to ensure the strength of the edge region of the cover 16. It may also be difficult to provide a sufficient lateral step size of the inner diameter expansion portion 113 of the side wall member 11 without making the first thickness t1 of the side wall member 11 too large.

[0126] The overhang 117 can reduce the melting time difference between the sidewall member 11 and the cover 16 by delaying the melting time of the relatively thin sidewall member 11. In addition, during the welding process, the overhang 117 can be expected to melt and flow into the welding area between the radial inner surface of the sidewall member 11 and the outer peripheral joint surface 171 of the cover 16. In this regard, the diameter of the outer peripheral joint surface 171 of the cover 16 can be slightly smaller than the diameter of the second inner surface 115 of the sidewall member 11 adjacent to the outer peripheral joint surface 171. In this context, when two objects are closely spaced relative to their outer dimensions, they are "adjacent" and there is no separate intervening object between the two in the relevant plane (i.e., the radial plane orthogonal to the central longitudinal axis). The diameter of the outer peripheral joint surface 171 of the cover 16 is slightly smaller than the diameter of the second inner surface 115 of the sidewall member 11, resulting in a small gap defined between the two components. Such a gap can be used as a path for the laser used for welding to directly irradiate the second collector plate 32. As described above, at least due to the interaction between the reduced thickness portion 161 of the cover 16 and the second collector plate 32, the cover 16 is centered, and such a gap is desirably of uniform width in the radial direction along the entire circumferential direction of the cover 16. In addition, during the welding process, the material of the overhang part 117 is desirably flowed into the gap between the outer peripheral bonding surface 171 of the cover 16 and the second inner surface 115 of the side wall member 11 so as to join the cover 16 and the side wall member 11 together. In an exemplary embodiment, the height h2 of the overhang part 117 is 0.2 mm, and the thickness t3 of the bonding portion 17 of the cover 16 is 0.5 mm. When the thickness t2 of the overhang part is 0.35 mm, it can provide sufficient material when it melts during welding, thereby forming a strong bond between the cover 16 and the side wall member 11. For example, the ratio of the overhang height h2 to the thickness t3 of the bonding portion 17 can be desirably in the range of 0.2 to 1.

[0127] During the process of forming the sealing portion S and / or the welding portion W, as Fig.12 and Fig.13 As shown, Fig.11 The overhang 117 in the cover 16 can be melted. As a result, the final total height of the battery cell can be defined by the outer surface of the cover 16. That is, as shown in the illustrated scheme, the seal portion S and / or the weld portion W do not contribute to the height of the battery cell, so that the height dimension of the battery cell can be uniformly managed.

[0128] In the following, reference is made to Fig.14 , an alternative scheme of the welding structure according to the present disclosure will be described. In such a description, in order to avoid repeated descriptions, the differences from the previous scheme will be mainly described. Therefore, it should be understood that in view of the description of other schemes, it can be fully understood that there is no combination Fig.14 In addition, it should be understood that as long as it does not conflict with the spirit of the present disclosure, the above-mentioned previous scheme and the following description Fig.14 Each element of the alternatives may be replaced with each other or omitted.

[0129] The side wall member 11 includes an inner diameter expansion portion 113 at the open end of the side wall member 11. The inner diameter expansion portion 113 has an inclined or deflected surface provided on the radial inner surface of the side wall member 11 to expand the inner diameter of the side wall member 11 near the upper axial end of the side wall member 11 at the open end. That is, the inner diameter expansion portion 113 is provided along the inner surface of the side wall member 11 and has an inclined surface oriented obliquely relative to the central longitudinal axis, so that the surface extends further outward in the radial direction when approaching the upper axial end of the side wall member 11.

[0130] The second current collector plate 32 includes a first bent portion 327, which is a portion of the second current collector plate 32 extending outward in the radial direction and bent upward so as to extend in the axial direction. Therefore, the peripheral portion of the second current collector plate (i.e., the tank connection portion 324) extends in the axial direction, rather than extending in the radial direction as in some existing solutions. As a result, the peripheral contact surface 325 of the second inner surface 115 of the side wall member 11 extends along the longitudinal dimension of the peripheral portion, rather than being defined by the terminal end of the peripheral portion. In contrast, Fig.14 In the embodiment of the present invention, the peripheral portion terminates in a cover contact surface 326 which abuts the collector plate contact surface 173 on the underside of the cover 16 along the bonding portion 17 .

[0131] As described above, the can connection portion 324 of the second current collector plate 32 is connected to the electrode tap connection portion 323 through the first bent portion 327 and the inner ring portion 321 .

[0132] Since the material of the second current collector plate 32 is softer than that of the side wall member 11, the first bent portion 327 is elastically deformed in the process of inserting the second current collector plate 32 into the open end of the side wall member 11. Therefore, when the outer diameter of the outer peripheral contact surface 325 is set to be slightly larger than the inner diameter of the second inner surface 115, the outer peripheral contact surface 325 is press-fitted into the second inner surface 115 so that the outer peripheral contact surface 325 is in close contact with the second inner surface 115 in the radial direction.

[0133] In terms of size, the outer peripheral surface portion of the first bent portion 327 of the second current collector plate 32 partially overlaps with the inner diameter expansion portion 113 of the side wall member 11. Therefore, even when there is a tolerance in the size of the second current collector plate 32 or the size of the side wall member 11, the outer peripheral surface of the second current collector plate 32 will strongly contact the radial inner surface of the side wall member 11.

[0134] according to Fig.14 In the structure of the second current collector plate 32 of the scheme, the cover contact surface 326 provided at the axial outer end of the tank connection portion 324 of the second current collector plate 32 has a width in the radial dimension substantially corresponding to the fifth thickness t5 of the second current collector plate 32. Therefore, the area of ​​the portion of the second current collector plate 32 in contact with the side wall member 11 can be larger than the area of ​​the portion of the second current collector plate 32 in contact with the cover 16. Therefore, compared with some other schemes of the present disclosure, the heat generated by the laser in the side wall member 11 can be dispersed and conducted more quickly through the second current collector plate 32, and the heat generated by the laser in the cover 16 can be dispersed and conducted relatively slowly through the second current collector plate 32. Therefore, the melting time of the side wall member 11, which is relatively thinner than the bonding portion 17 of the cover 16, can be further delayed.

[0135] In addition, since a portion of welding heat transmitted through the sidewall member 11 is dispersed through the second current collector plate 32 , heat transfer to the separator 28 of the electrode assembly 20 , which contacts the first inner surface 111 of the sidewall member 11 , may be further reduced.

[0136] The reduced thickness portion 161 of the cover 16 in the modified example is arranged further outward in the radial direction than the reduced thickness portion 161 of the cover 16 of the previous scheme. Therefore, a larger area of ​​the cover body 160 can be achieved. In addition, the reduced thickness portion 161 is also provided in the form of an inclined surface so that during the insertion process of the cover 16 in contact with the second collector plate 32, the reduced thickness portion 161 can guide the center alignment of the cover 16.

[0137] According to the above-mentioned various schemes, although the range of the welding process is wide, the sealing force can be ensured without perforation or liquid leakage, and the welding performance can be improved. In addition, the process stability can be improved by preventing thermal damage to the unit components or the diaphragm caused by welding heat, and the durability can also be improved by obtaining dimensional stability and anti-bulging properties by suppressing dimensional deformation caused by internal pressure.

[0138] Below, refer to Figures 7 to 10 and Fig.16 , an example of a method for manufacturing the above-mentioned battery cell will be described.

[0139] According to the manufacturing method of the battery cell, the can 10 in which the first electrode terminal 13 is fixed to the bottom member 12 is prepared, and then the electrode assembly 20 having both ends coupled to the first and second current collector plates 31 and 32 in the axial direction is prepared.

[0140] Then, the electrode assembly 20 is accommodated in the can 10 so that the first current collector plate 31 faces the bottom member 12. As a result, the second current collector plate 32 is located on the open end side of the can 10. In the process of accommodating the electrode assembly 20 in the can 10, the outer peripheral contact surface 325 of the can connection portion 324 provided at the radial outer edge of the second current collector plate 32 in the radial direction contacts the second inner surface 115 of the sidewall member 11.

[0141] Here, the tank connection portion 324 of the second current collector plate 32 contacts the inner diameter expansion portion 113 of the sidewall member 11 , thereby improving adhesion strength of the current collector plate 32 to the radial inner surface of the sidewall member 11 and adjusting an insertion depth of the second current collector plate 32 .

[0142] Next, the first current collector plate 31 and the first electrode terminal 13 are combined.

[0143] Then, an electrolyte solution is injected into the tank 10 .

[0144] After the electrolyte injection is completed, in the case where the open end of the side wall member 11 is covered by the cover 16, the peripheral bonding surface 171 and the current collector plate contact surface 173 provided at the edge of the cover 16 are respectively in contact or facing with the second inner surface 115 of the side wall member 11 and the cover contact surface 326 of the second current collector plate 32. In this way, the thickness reduction portion 161 in the form of an inclined surface provided on the lower side of the cover 16 can be brought into contact with the second current collector plate 32 so as to align with the center of the cover 16.

[0145] After that, laser is irradiated on the contact area between the second inner surface 115 of the side wall member 11 and the outer peripheral joint surface 171 of the cover 16 from the outside of the battery cell in the axial direction to weld the radial inner surface of the side wall member 11, the outer peripheral joint surface 171 of the cover 16, and the tank connection portion 324 of the second current collector plate 32 to each other. Thus, the welding portion W combines the side wall member 11, the cover 16, and the second current collector plate 32 together.

[0146] During the welding process, the overhang 117 of the sidewall member 11 protruding outward more than the cover 16 in the axial direction may melt and flow into the welding area between the radial inner surface of the sidewall member 11 and the outer peripheral joining surface 171 of the cover 16 .

[0147] The battery cell 72 manufactured by the above-mentioned welding structure and welding process can be accommodated in the housing 71 of the battery pack 70, as shown in FIG. Fig.17The battery pack 70 may be constructed using one or more battery modules, each of which is an intermediate form of assembly containing a plurality of battery cells 72. Alternatively, as shown, the battery pack 70 may be constructed directly from a plurality of battery cells 72 without any intervening battery modules.

[0148] Since the battery cell 72 has a large volume, there is no particular difficulty in implementing the battery pack 70 even without using an intermediate structure such as a battery module. In addition, the battery cell 72 has a smaller internal resistance and a higher energy density than a conventional battery cell. Therefore, the energy density of the battery pack 70 including the battery cell 72 can be higher.

[0149] A battery pack 70 with this increased energy density can store the same amount of energy while reducing its volume and weight. Fig.18 As shown, when the battery pack 70 to which the battery cell 72 is applied is mounted on a vehicle such as an automobile 80 that uses electricity as an energy source, the driving range of the vehicle with respect to energy can be further extended.

[0150] Although the above seam welding structures and methods are disclosed in the context of cylindrical battery cans, it should be understood that within the scope of the present disclosure, such technology can be similarly applied to other battery form factors. For example, the associated battery cells do not need to have a circular cross-sectional profile orthogonal to the central longitudinal axis, but other cross-sectional shapes can be used, including elliptical, square, rectangular, partially circular, etc. In addition, the central longitudinal axis does not need to be oriented orthogonally to the bottom member and / or cover at the corresponding opposite ends. For example, the side wall member of the can (together with the internal components of the can) can form a tube extending along an axis oriented obliquely relative to the plane defined by the bottom member and / or cover. In addition, the welding techniques disclosed herein can also be used outside the context of cylindrical battery cans, and can also be applied to batteries with square and pouch-shaped form factors, for example.

[0151] Non-limiting benefits that may be provided by some or all of the embodiments of the present disclosure include improved welding performance, wherein the side wall members, the cover, and the current collector plate can all be welded to each other. Improved process stability for welding the side wall members, the cover, and the current collector plate together can also be obtained. Increased durability of the weld area between the side wall members and the cover can also be obtained. In addition, at least by welding the side wall members, the cover, and the current collector plate together as part of the same welding process, the battery cell assembly time can be greatly reduced.

[0152] The above scheme should be understood in all aspects as illustrative rather than restrictive, and the scope of the present disclosure will be represented by the claims rather than the detailed description given above. In addition, all changes and modifications derived from the meaning and scope of equivalent concepts and patent claims should be interpreted as included in the scope of the present disclosure.

[0153] As described above, the present disclosure has been described with reference to the illustrative drawings, but the present disclosure is not limited to any scheme and drawings disclosed herein, and those skilled in the art may make various modifications within the scope of the technical idea of ​​the present disclosure. In addition, when explaining the various schemes of the present disclosure, all operational effects produced by the present disclosure are not explicitly described and explained here, but those of ordinary skill in the art will recognize such predictable effects.

Claims

1. A battery cell, characterized in that: The battery unit includes: a can having a sidewall member defining an interior volume and defining an opening to the interior volume at a first end of the can along a central longitudinal axis; an electrode assembly received within the interior volume of the can; a current collector plate electrically connected to the electrode assembly; and a lid covering the opening of the can so as to close the interior volume, wherein the current collector plate includes a central portion and a peripheral portion, the central portion being electrically connected to an electrode tab of the electrode assembly, and the peripheral portion being positioned around the central portion and being spaced further from the central longitudinal axis than the central portion, the peripheral portion being in contact with a radially inner surface of the sidewall member so as to be electrically connected to the can, and the peripheral portion being in contact with a lower side of the cover facing the internal volume in an axial direction extending parallel to the central longitudinal axis, and wherein the radially inner surface of the side wall member, the radially outer surface of the cover, and the peripheral portion of the collector plate are welded to each other.

2. The battery cell according to claim 1, characterized in that: The radially inner surface of the sidewall member includes a transverse step extending transversely to the central longitudinal axis, such that a first inner surface of the sidewall member positioned on a first side of the transverse step in the axial direction has a first diameter, and a second inner surface of the sidewall member positioned on a second side of the transverse step in the axial direction has a second diameter, the second side of the transverse step being closer to the opening than the first side, and the second diameter being greater than the first diameter, and wherein the radially outer surface of the cover and the peripheral portion of the collector plate are in contact with the second inner surface.

3. The battery cell according to claim 2, characterized in that: The outer diameter of the peripheral portion of the current collector plate is greater than the first diameter of the first inner surface.

4. The battery cell according to claim 2, characterized in that: The peripheral portion of the current collector plate is in contact with the transverse step.

5. The battery cell according to claim 2, characterized in that: The transverse step is defined by a sloped surface extending from the first diameter of the first inner surface to the second diameter of the second inner surface.

6. The battery cell according to claim 2, characterized in that: A first thickness of the cover in the axial direction along the radially outer surface is greater than a second thickness of the sidewall member in a radial direction along the second inner surface, the radial direction being perpendicular to the central longitudinal axis.

7. The battery cell according to claim 6, characterized in that: The first thickness is between one and two times the second thickness.

8. The battery cell according to claim 1, characterized in that: The radially outer surface of the cover has a diameter that is smaller than a diameter of an adjacent portion of the radially inner surface of the sidewall member, and wherein a weld region extends from the adjacent portion of the radially inner surface of the sidewall member to the radially outer surface of the cover.

9. The battery cell according to claim 1, characterized in that: The cover comprises an annular region extending along the radially outer surface, and wherein a thickness of the annular region of the cover in the axial direction is smaller than a thickness of a central region of the cover located along the central longitudinal axis.

10. The battery cell according to claim 9, characterized in that: An inclined surface along the underside of the cover connects the annular region and the central region.

11. The battery cell according to claim 10, characterized in that: The inclined surface contacts the current collector plate.

12. The battery cell according to claim 1, characterized in that The current collector plate includes a step between the central portion and the peripheral portion in the axial direction such that the peripheral portion is offset relative to the central portion toward the opening of the can.

13. The battery cell according to claim 1, characterized in that The longitudinal dimension of the central portion of the collector plate extends transversely to the axial direction, and wherein the longitudinal dimension of the peripheral portion of the collector plate extends parallel to the axial direction, so that the peripheral portion extends along the radial inner surface of the side wall member of the tank to the terminal end of the peripheral portion adjacent to the lower side of the cover.

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