Cylindrical battery cells, and battery packs and automobiles containing them.

Abstract

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

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0068532 filed on June 3, 2022 and Korean Patent Application No. 10-2023-0026174 filed on February 27, 2023, and all the contents disclosed in the documents of the Korean patent applications are included as part of this specification.

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

Background Art

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

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

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

[0006] As described above, cylindrical battery cells require space inside the can to accommodate the second current collector plate, which necessitates a reduction in the volume of the electrode assembly, resulting in lower energy density. Furthermore, the traditional manufacturing process for cylindrical battery cells requires an additional step of fabricating the second current collector plate and connecting it to the second electrode of the electrode assembly, which increases the unit cost of manufacturing the battery cell. [Overview of the project] [Problems that the invention aims to solve]

[0007] The present invention was devised to solve the above-mentioned problems, and aims to provide a battery cell that can provide reliable electrical connection between the electrodes of the electrode assembly and the electrode terminals of the can, even though a current collector plate is omitted when connecting the electrode assembly to the electrode terminals of the can.

[0008] This invention aims to provide a battery cell that has fewer parts and manufacturing steps, is simpler to use, and can reduce the unit cost of manufacturing.

[0009] The present invention aims to provide a battery cell with high energy density that is advantageous for mounting in a vehicle, as well as a battery pack and an automobile containing the same. [Means for solving the problem]

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

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

[0012] According to at least some aspects of the present invention, the at least one tab may include a plurality of tabs extending radially perpendicular to the axial direction so that they overlap each other at least partially along the axial direction.

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

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

[0015] According to at least some aspects of the present invention, the electrode connecting portions may be connected to each other by protrusions of the cap in the radial central region of the cap, and the protrusions may project axially toward the interior of the battery can.

[0016] According to at least some aspects of the present invention, the electrode connecting portions may be connected to one another by projections extending around the radially outer region of the cap, the projections may project axially toward the interior of the battery can.

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

[0018] According to at least some aspects of the present invention, the cap may include a liquid filling port located in the center of the cap. These liquid filling ports may be located in a central protruding region of the cap, and the central protruding region may be located further axially from the inside of the battery can than each of the contact surfaces of each of the electrode connecting portions. The contact surfaces may be in direct electrical contact with the tab(e.g.) of the second electrode.

[0019] According to some aspects of the present invention, the space between circumferentially separated electrode connecting portions can be defined as an intermediate region. These intermediate regions may be located further from the inside of the battery can than the contact surface of the electrode connecting portions in the axial direction. In some aspects of these aspects of the present invention, the central protruding region of the cap may be radially separated from the intermediate region by the outer surface portion of the cap, which is located closer to the inside of the battery can than the central protruding region and the intermediate region in the axial direction. In other aspects of these aspects of the present invention, the central protruding region of the cap may be directly adjacent to the intermediate region in the radial direction.

[0020] According to at least some aspects of the present invention, the cap may include vents. These vents may be located radially outward from the electrode connection portion.

[0021] According to at least some aspects of the present invention, the first electrode terminals are located along the closed end of the battery can. These electrode terminals can be electrically insulated from the closed end of the battery can. The first electrode of the electrode assembly may also be electrically connected to the first electrode terminals via a first current connecting plate located axially between the electrode assembly and the closed end of the battery can.

[0022] According to at least some aspects of the present invention, the cap may be configured and arranged such that the outermost surface of the cap that is axially furthest from the inside of the battery can is located further axially from the inside of the battery can than the open end of the battery can.

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

[0024] According to at least some aspects of the present invention, the electrode connecting portion may extend radially. In some of these aspects, the electrode connecting portion may extend linearly along a straight line extending through the center of the cap.

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

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

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

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

Effect of the Invention

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

[0030] According to some embodiments of the present invention, the electrode connection portion of the cap connected to one or more tabs of the second electrode extends radially, so that the cap is electrically directly connected from the core portion to the outer circumference portion of the second electrode, thereby greatly reducing internal resistance.

[0031] According to some embodiments of the present invention, the cap is provided with a plurality of radially extending electrode connecting portions, and each electrode connecting portion is recessed in the axial direction so as to protrude axially toward the inside of the battery can, and protrudes toward the tab of the second electrode. This ensures tight contact between each electrode connecting portion and the tab of the second electrode, thereby ensuring the quality of the bond between them.

[0032] Furthermore, these shapes significantly improve the torsional resistance of the cap. They also increase the connection strength between the periphery of the cap and the open end of the battery case. Therefore, the quality of the bond between the battery case and the cap can be greatly improved.

[0033] According to some embodiments of the present invention, the electrode connecting portions of the cap are arranged radially and at equal intervals in the circumferential direction, ensuring uniform torsional resistance along the circumferential direction, and allowing for a uniform distribution of the current path.

[0034] According to some embodiments of the present invention, a pair of electrode connecting portions facing each other across the center of the cap are aligned in a line, and the shape of the jig can be simply realized for pressing the cap into the battery can or for making it tightly attached to the electrode assembly, thereby simplifying the trajectory of the welding line.

[0035] According to some embodiments of the present invention, four electrode connecting portions are arranged at 90-degree intervals, increasing the torsional resistance of the cap, simplifying the welding process, and increasing the joint strength between the tab of the second electrode and the multiple electrode connecting portions. Furthermore, it is possible to suppress plastic deformation of the cap and prevent a decrease in the rigidity of the cap.

[0036] According to some embodiments of the present invention, a press-fit connection can be provided in which the centrifugal edges of a plurality of electrode connecting portions contact the inner circumferential surface of the battery can, guiding the center alignment of the cap relative to the battery can. During the process of pressing the can into the battery can, the center of the cap can be naturally aligned with the battery can.

[0037] According to some embodiments of the present invention, the depth of insertion of the cap is restricted by the electrode connecting portion, so that sufficient adhesion is ensured between the electrode connecting portion and the tab (etc.) of the second electrode, and the joining may be performed in this manner.

[0038] According to the present invention, the outermost surface of the cap, which is located further outward in the axial direction than the joint between the cap and the battery can, is positioned between two circumferentially adjacent electrode connecting portions, thereby protecting the joint portion.

[0039] When the battery can is placed correctly, that is, with its outermost surface facing the floor, the outermost surface supports the load of the battery cells. At this time, the outermost surfaces located on both sides of the circumferential direction of the electrode connection exert a pressure on the electrode connection towards the tab of the second electrode. Therefore, the phenomenon of damage to the joint between the cap and the tab of the second electrode due to vibration or shock can be minimized.

[0040] The liquid injection port located in the center of the cap allows for diversification of the battery cell manufacturing process. Furthermore, by having the liquid injection port protrude beyond the electrode connection portion, the phenomenon of welding heat or joining heat generated when the liquid injection port is sealed with a stopper being transferred to the electrode assembly can be minimized.

[0041] If the vent provided in the cap is located radially outward from the electrode connection or weld, a larger area of ​​the cap on which the pressure resistance of the battery can acts can be secured, the venting action can occur more easily, and if the vented area is damaged by the vent, the electrical connection between the second electrode and the battery can can be interrupted.

[0042] The above-mentioned and other objectives, features and advantages of the present invention will become apparent to those skilled in the art through the detailed description of embodiments of the invention below, with reference to the drawings described later. [Brief explanation of the drawing]

[0043] [Figure 1] This is a perspective view of the cylindrical battery cell of the embodiment. [Figure 2] This is a perspective view showing the state of the electrode assembly before the first electrode, second electrode, and separation membrane are laminated, in order to fabricate the electrode assembly that will be housed in the battery can. [Figure 3] This is a perspective view showing the state after the first electrode, second electrode, and separation membrane have been laminated, in order to fabricate an electrode assembly that will be housed in a battery case. [Figure 4] Figure 3 is a plan view of the stacked state. [Figure 5] Figures 3 and 4 show perspective views of electrode assemblies fabricated by winding the laminated material into a jelly roll. [Figure 6] Figures 3 and 4 are side views of an electrode assembly fabricated by winding the laminated material into a jelly roll. [Figure 7] This is a perspective view showing the electrode assembly with a current collector plate attached to the upper part and no current collector plate attached to the lower part. [Figure 8] This is a perspective view showing the electrode assembly with a current collector plate attached to the upper part and no current collector plate attached to the lower part. [Figure 9] Figures 7 and 8 are multi-view diagrams showing the process of housing the electrode assemblies into the battery case. [Figure 10] This is a cross-sectional view showing the process of welding the first electrode terminal to the current collector plate. [Figure 11] This is a cross-sectional view showing the process of placing a cap on a battery can. [Figure 12] This is a cross-sectional view showing the cap joined to the tab of the second electrode of the electrode assembly and then joined to the axial edge of the battery can. [Figure 13] This is a top perspective view of the cap of the first embodiment. [Figure 14] This is a lower perspective view of the cap of the first embodiment. [Figure 15] This is a plan view of the cap of the first embodiment. [Figure 16] This is a cross-sectional view of the area taken from line XVI-XVI in Figure 15. [Figure 17] This is a cross-sectional view of the area taken from line XVII-XVII in Figure 15. [Figure 18] This is a cross-sectional view showing the process of assembling a battery can by applying the cap of the first embodiment. [Figure 19] This is a top perspective view of the cap of the second embodiment. [Figure 20] This is a lower perspective view of the cap of the second embodiment. [Figure 21] This is a plan view of the cap of the second embodiment. [Figure 22] This is a cross-sectional view of the area taken from the line XXII-XXII in Figure 21. [Figure 23] This is a cross-sectional view of the area taken from the line XXIII-XXIII in Figure 21. [Figure 24] This is a cross-sectional view showing the process of assembling a battery can by applying the cap of the second embodiment. [Figure 25] This is a top perspective view of the cap of the third embodiment. [Figure 26] This is a plan view of the cap of the third embodiment. [Figure 27] This is a cross-sectional view of the area taken from the line XXVII-XXVII in Figure 26. [Figure 28] This is a cross-sectional view showing the process of assembling a battery can by applying the cap of the third embodiment. [Figure 29] This is a cross-sectional view showing the process of assembling a battery can by applying the cap of the third embodiment. [Figure 30] This is a perspective view showing the electrode assembly with the tab and cap of the second electrode already joined together, before it is placed in the battery case. [Figure 31] This is a top perspective view of the cap of the fourth embodiment. [Figure 32] This is a plan view of the cap of the fourth embodiment. [Figure 33] This is a cross-sectional view of the area taken from the line XXXIII-XXXIII in Figure 32. [Figure 34] This is a cross-sectional view showing the process of assembling a battery can by applying the cap of the fourth embodiment. [Figure 35] This is a cross-sectional view showing the process of assembling a battery can by applying the cap of the fourth embodiment. [Figure 36] This is a top perspective view of the cap of the fifth embodiment. [Figure 37] This is a cross-sectional view of the area taken from the line XXXVII-XXXVII in Figure 36. [Figure 38] This is a cross-sectional view of the area taken from the line XXXVIII-XXXVIII in Figure 36. [Figure 39] This flowchart shows an example of a method for assembling a battery cell with the cap from the example applied. [Figure 40] This flowchart shows an example of a method for assembling a battery cell with the cap from the example applied. [Figure 41] This flowchart shows an example of a method for assembling a battery cell with the cap from the example applied. [Figure 42] This is a perspective view of a battery pack to which the battery cells of the embodiment are applied. [Figure 43] Figure 42 is a diagram showing a vehicle equipped with a battery pack. [Modes for carrying out the invention]

[0044] The aforementioned objectives, features, and advantages will be described in detail later with reference to the attached drawings. In describing the present invention, if a specific description of known technology according to the present invention is deemed to obscure the gist of the present invention, the detailed description will be omitted. The same reference numerals in the drawings are used to indicate the same or similar components.

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

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

[0047] In the following, the placement of any configuration "above (or below)" a component or "above (or below)" a component means not only that the configuration is placed in contact with the upper (or lower) surface of the component, but also that other configurations may be interposed between the component and any configuration placed on (or below) it.

[0048] Furthermore, where it is stated that one component is “linked,” “joined,” or “connected” to another component, it should be understood that the components may be directly linked or connected to one another, but may also be “interposed” between each component, or each component may be “linked,” “joined,” or “connected” through other components.

[0049] As used herein, singular expressions include plural expressions unless the context clearly indicates otherwise. Terms such as “composed of” or “including” in this application should not be construed as necessarily including all of the multiple components or stages described in the specification, and should be construed as meaning that some of the components or stages may not be included, or that further components or stages may be included.

[0050] 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 greater and D or less unless otherwise specified.

[0051] In describing the embodiments, the axial direction refers to the direction in which the axis forming the winding center of the jelly roll type electrode assembly extends, the radial direction refers to the direction in which the axis approaches (centripetal) or moves away from (centrifugal) the axis, and the circumferential direction refers to the direction surrounding the axis, with the axis being the outer circumference of a circle.

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

[0053] The structure of a cylindrical battery cell according to an embodiment of the present invention will be described below with reference to Figures 1 to 8.

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

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

[0056] The battery cell used in the pressure tester may be a cylindrical battery cell that is roughly cylindrical in shape, with a diameter of approximately 46 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0057] The battery cell according to another embodiment may be a cylindrical battery cell that is substantially cylindrical in shape, with a diameter of substantially 48 mm, a height of substantially 75 mm, and a form factor ratio of 0.640.

[0058] Furthermore, a battery cell according to another embodiment may be a cylindrical battery cell that is substantially cylindrical in shape, with a diameter of substantially 48 mm, a height of substantially 110 mm, and a form factor ratio of 0.418.

[0059] Furthermore, a battery cell according to another embodiment may be a cylindrical battery cell that is substantially cylindrical in shape, with a diameter of substantially 48 mm, a height of substantially 80 mm, and a form factor ratio of 0.600.

[0060] Furthermore, a battery cell according to another embodiment may be a cylindrical battery cell that is substantially cylindrical in shape, with a diameter of substantially 46 mm, a height of substantially 80 mm, and a form factor ratio of 0.575.

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

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

[0063] A hole may be formed in the center of the bottom portion 12, and the first electrode terminal 13 may be inserted into the hole and connected. The first electrode terminal 13 can be fixed to the bottom portion 12 by riveting it with a terminal gasket 14 interposed between them. The terminal gasket 14 is interposed between the first electrode terminal 13 and the bottom portion 12 to seal the inside and outside of the battery can 10, prevent electrolyte leakage, and electrically insulate the first electrode terminal 13 from the bottom portion 12.

[0064] However, the method of connecting the first electrode terminal 13 and the bottom portion 12 is not limited to this. For example, any other fixing method that can be used to electrically insulate the first electrode terminal 13 and the bottom portion 12 by sealing the space between them is also applicable, such as a bolt-nut connection method, a glass seal method, or a PP-MAH thermal bonding method.

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

[0066] In this case, the battery can 10 may have both the first electrode terminal 13 and the second electrode terminal 15 positioned at one axial end. In this case, the busbar connected to the first electrode terminal 13 and the busbar connected to the second electrode terminal 15 may both be located at one axial end, i.e., the upper part, of the battery can 10.

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

[0068] An electrode assembly 20 is housed inside the battery can 10. As shown in Figure 2, the electrode assembly 20 is prepared by preparing a first electrode 21, a second electrode 22, and a separation membrane 28 that have a predetermined width and extend in the longitudinal direction. As shown in Figures 3 and 4, a laminate is formed by stacking the first electrode 21, separation membrane 28, second electrode 22, and separation membrane 28 in that order, and then this is wound around a core shaft to produce a jelly roll.

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

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

[0071] The plain area 26 is exposed or protrudes in the width direction of the laminate. The plain area 26 itself functions as an electrode tab. Although here the term "electrode tab" refers to the integrated portion of the metal foil 23 that protrudes outward from the electrode assembly 20, these "tabs" may be separately manufactured and have an electrically conductive configuration that is firmly electrically coupled to the current-collecting metal foil 23 of the electrode.

[0072] Notches can be formed in the plain portion 26 at predetermined intervals to create flag-shaped notched tabs 27.

[0073] In the embodiment, the notched tab 27 is exemplified as being in the shape of an equilateral trapezoid. However, these shapes may be of various forms, such as semicircular, inverted elliptical, triangular, rectangular, or parallelogram shapes.

[0074] Furthermore, in the embodiment, a configuration is shown in which 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 wider from the core side to the outer circumference side.

[0075] Furthermore, in the embodiment, a configuration is shown in which the height of the notched tab 27 gradually increases from the core side to the outer circumference side. However, the height of these notched tabs may be constant or gradually decrease.

[0076] In the jelly roll type electrode assembly 20, the notched tab 27 may be bent radially inward or outward. In the embodiment, as shown in Figures 5 and 6, a structure in which the notched tab 27 is bent radially inward is exemplified.

[0077] The notched tabs 27 can be bent one by one during the process of winding up the laminate to form the jelly roll-type electrode assembly 20. Alternatively, the notched tabs 27 can also be bent all at once after winding up the laminate to form the jelly roll-type electrode assembly.

[0078] 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 overlapping, can provide substantially perpendicular planes to the axial direction at both axial ends of the electrode assembly 20, as shown in Figure 6.

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

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

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

[0082] The electrode connecting portion 34 is joined to the notched tab 27 of the first electrode 21 of the electrode assembly 20 by a method such as laser welding before the electrode assembly 20 is placed in the battery can 10.

[0083] Referring to Figure 8, a current collector plate does not need to be connected to the notched tab 27 of the second electrode 22 of the electrode assembly 20.

[0084] As shown in Figures 9 and 10, the electrode assembly 20 is housed in the battery can 10 with the current collector plate 31 aligned so that it faces the bottom 12 of the battery can 10. At this time, an insulator 19 is interposed between the current collector plate 31 and the bottom 12 of the battery can 10 to electrically insulate the current collector plate 31 from the bottom 12.

[0085] The terminal connection portion 32 of the current collector plate 31 is joined to the first electrode terminal 13 by resistance welding, ultrasonic welding, or laser welding. For welding the current collector plate 31 and the first electrode terminal 13, the welding apparatus 100 can approach the back surface of the center of the terminal connection portion 32 of the current collector plate 31 in the axial direction via the hollow core portion of the electrode assembly 20 and perform the welding. Of course, the current collector plate 31 and the first electrode terminal 13 can also be joined by brazing or soldering.

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

[0087] The cap 40 is made of an electrically conductive material. The cap 40 can also be manufactured integrally from these materials. The edge of the cap 40 is joined to the side wall 11 of the battery can 10, electrically connecting and sealing it. This allows the second electrode 22 to be electrically connected to both the cap 40 and the battery can 10. Various methods can be applied to join the cap 40 and the battery can 10, such as welding, brazing, or soldering, which electrically connect and seal the components.

[0088] The cap 40 and its assembly process shown in Figures 11 and 12 are illustrative examples, and various embodiments of the structure of the cap 40 and the assembly method thereof will be described below. In the embodiments described later, these joints are shown to be joined by welding, but it goes without saying that the present invention is not limited thereto.

[0089] [First Embodiment] In the following, with reference to Figures 13 to 18, we will describe a first embodiment of the cap and the structure of a battery cell to which it is applied.

[0090] The cap 40 can be manufactured from a circular metal sheet. The cap 40 comprises one or more electrode connectors 41 recessed in a direction corresponding to the axial direction of the battery cell 72. The electrode connectors 41 can be formed by stamping, such as pressing the metal sheet with a press and one or more shaped dies. Thus, these stampings allow each protrusion defined by the electrode connectors 41 on the lower side of the cap 40 to correspond to each recess on the upper side of the cap.

[0091] The bottom surface of the electrode connecting portion 41 defines a contact surface that is in close contact with and joined to the notched tab 27 of the second electrode 22 of the electrode assembly 20. The electrode connecting portion 41, which is manufactured by press-forming a metal sheet, is slightly thinner than the thickness of the metal sheet. As a result, when a laser (L) is irradiated onto the surface of the electrode connecting portion 41, the localized heat generated by the laser can melt and join the electrode connecting portion 41 and the surface of the notched tab 27 that is in contact with the contact surface of the bottom surface of the electrode connecting portion 41.

[0092] The electrode connecting portion 41 is provided as a plurality of protrusions that project downward in the axial direction toward the interior of the battery can 10. In the embodiments shown in Figures 13 to 18, four electrode connecting portions 41 are formed radially by extending linearly along their respective radial directions. Preferably, these electrode connecting portions 41 are arranged at equal intervals in the circumferential direction with respect to the center 46 of the cap 40. In the case of these four electrode connecting portions 41, they may be spaced at 90-degree intervals. The electrode connecting portions 41 are also connected to each other in the central radial region of the cap 40, and the central region of the cap 40 can similarly form protrusions that project downward in the axial direction toward the interior of the battery can 11. These central protrusions may be formed continuously with the same depth as the electrode connecting portions 41. Therefore, when there are four electrode connecting portions 41 at equal intervals, these electrode connecting portions and the central protrusions connecting them align to form a cross shape, as shown in Figures 13 to 15.

[0093] The welded portion (W) for joining one or more electrode connecting portions 41 to the notched tab 27 of the second electrode 22 of the electrode assembly 20 may have a linear shape formed radially so as to correspond to the extending direction of the electrode connecting portion 41.

[0094] According to the embodiment, a welded portion (W) with a linear, radially aligned and extending shape is formed for each of the multiple electrode connecting portions 41.

[0095] The cap 40 provides the outermost surface 44 that contacts the ground when the battery can 10 is placed upright with the cap 40 facing the floor. Each outermost surface 44 is positioned higher than the electrode connecting portion 41 (for example, further away from the inside of the battery can 10 in the axial direction) and is located between two adjacent electrode connecting portions 41 in the circumferential direction.

[0096] This allows the outermost surface 44 to be pressed axially with a jig, bringing the electrode connection portion 41 and the notched tab 27 into close contact, and then a laser is irradiated onto the surface of the electrode connection portion 41 to weld the electrode connection portion 41 and the notched tab 27. As a result, on both opposing sides of the welding line, the pressure from the jig presses the electrode connection portion 41 tightly against the notched tab 27, ensuring reliable welding.

[0097] The pair of electrode connecting portions 41 facing each other with respect to the center 46 of the cap 40 are arranged in a manner that they lie on a straight line passing through the center 46 of the cap 40. This allows the welding line of the two electrode connecting portions 41 aligned in a line to be formed with only one movement of the laser welding machine when forming a welding line. For example, if the first electrode connecting portion, second electrode connecting portion, third electrode connecting portion, and fourth electrode connecting portion are arranged sequentially along the circumferential direction of the cap 40 in the first embodiment, the first electrode connecting portion and the third electrode connecting portion may be welded at the same time, and the second electrode connecting portion and the fourth electrode connecting portion may be welded at the same time.

[0098] Furthermore, according to the embodiment, even when the outermost surface 44 between the first electrode connection and the third electrode connection is pressed with a jig, the second moment of inertia formed by the recessed shape of the second and fourth electrode connection is large, allowing the cap 40 to move as a rigid body without twisting or bending despite the pressure of the jig. In fact, it is believed that the strength and rigidity of the cap 40 can be increased particularly efficiently without adding material and weight by having at least two electrode connections 41 located on opposing sides of the center 46 of the cap 40. In this regard, without being limited to a specific operating theory, arranging these electrode connections 41 along a straight line extending through the center 46 of the cap, in particular, if these electrode connections extend along that line (and from the central region of the cap 40 to the opposing sides), these arrangements would define part of the cap structure similar to a reinforcing beam extending across the cap. Furthermore, having four electrode connecting portions 41 arranged at equal intervals around the center 46, extending along two mutually orthogonal straight lines, is considered to further reinforce the cap, similar to a vertical beam with moment-resistive coupling between them.

[0099] In this embodiment, by configuring four electrode connecting portions 41 as described above, all four electrode connecting portions 41 can be welded in two laser scan trajectories.

[0100] If too many electrode connecting portions 41 are processed, the strength of the cap 40 made from the metal sheet may be weakened. Also, if only two or three electrode connecting portions 41 are formed, it is difficult to construct a cross-section that ensures a sufficient second moment of inertia along the circumferential direction.

[0101] As shown in the embodiment, by arranging the four electrode connecting portions 41 on the cap 40 in a cross shape or a "+" shape, the welding process can be performed accurately and simply, the torsional and bending resistance of the cap 40 can be improved, and the weakening of the cap 40's strength due to the molding process can be reduced or prevented. Furthermore, the cap 40 not only provides the function of a current collector plate, but also maintains the strength necessary for its original function of closing the open end of the battery can 10.

[0102] The radial outer edge of the cap 40 has a shape that allows it to be joined to the axial end of the side wall portion 11 at the open end of the battery can 10. For this reason, the electrode connecting portion 41 may be formed radially inward from the outer edge of the cap, thereby defining a joining surface 47 on the bottom surface of the radial outer edge of the cap 40, which has a circular profile extending from the center 46 of the cap 40. As shown in Figure 18, the joining surface 47 of the cap 40 is in contact with the axial end surface of the side wall portion 11 at the open end of the battery can 10, and these contact surfaces can be welded by a laser irradiated radially inward along the outer circumference of the battery can 10 to form a joint (M).

[0103] The radial outer edge of the electrode connecting portion 41 can define a recessed outer wall 45 with an outer diameter corresponding to the inner diameter of the battery can 10. Therefore, when the cap 40 is assembled onto the battery can 10, the recessed outer walls 45 of the multiple electrode connecting portions 41 slide against the inner circumferential surface of the battery can 10 and are pushed in, guiding the center alignment of the cap 40 relative to the battery can 10.

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

[0105] Thus, the cap 40 of the embodiment has the advantage of being easy to assemble because the recessed outer wall 45 is formed at the same time as the electrode connecting portion 41 is formed.

[0106] Furthermore, according to the structure of the cap 40 in the embodiment, since the laser is aligned radially and irradiated to weld the cap 40 and the battery can 10, even if, due to unforeseen errors, the joining surface 47 of the cap 40 does not come into close contact with the axial end of the side wall portion 11 in one or more areas, the laser will not be aligned in a way that damages the electrode assembly 20 inside the battery can 10.

[0107] According to the first embodiment, the outermost surface 44 of the cap 40 is located further outward in the axial direction than the joint (M) between the cap 40 and the battery can 10, so that the battery can 10 in Figure 18 can be turned upside down and stood upright correctly. Therefore, the joint (M) does not come into direct contact with the ground, and it is easy to protect the joint (M).

[0108] By applying the cap 40 described above, it is not necessary to use a current collector plate to electrically connect the tab of the second electrode 22 to the battery can 10. Therefore, the number of parts and assembly steps can be reduced, further internal volume can be secured, and energy density can be increased. The cap 40, which is electrically connected to the battery can 10, is directly connected to the metal foil 23 of the second electrode of the electrode assembly 20, but because it is connected via a radially extending weld (W), the current path is preferably uniformly distributed, and internal resistance can be greatly reduced.

[0109] [Second Example] In the following, a second embodiment of the cap and the structure of a battery cell to which it is applied will be described with reference to Figures 19 to 24. In describing the second embodiment, any content that overlaps with the first embodiment described above can be omitted. Therefore, any part not described in one embodiment can be understood from the other embodiments. Furthermore, it is easy to understand that the configurations of one embodiment and the configurations of other embodiments can be substituted for, added to, or omitted from each other.

[0110] The cap of the second embodiment differs from the cap of the first embodiment in that an annular projection 48 extends along the radial outer edge region of the cap 40, and the annular projection 48 protrudes downward in the axial direction toward the interior of the battery can 10. The annular projection 48 connects various electrode connecting parts 41. The radial outer edge of the cap 40 is defined by the radial outer edge of the annular projection 48, and this outer edge is configured to be located within the inner diameter of the side wall 11. Thus, the radial outer edge constitutes a recessed outer wall 45.

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

[0112] Unlike the first embodiment, the cap 40 of the second embodiment can be pressed into the battery can 10 by the outer surface of the pressing outer wall 45 contacting the inner surface of the battery can 10, as shown in Figure 24. The pressing outer wall 45 does not restrict the depth to which the cap 40 is pressed in axially. The depth to which the cap 40 is pressed in in the second embodiment can be restricted by the electrode connecting portion 41. That is, the cap 40 can be pressed in until the bottom surface of the electrode connecting portion 41 is in close contact with the notched tab 27 of the electrode assembly 20.

[0113] In this state, the electrode connecting portion 41 and the notched tab 27 are welded together in the longitudinal direction, i.e., radial direction, of the electrode connecting portion to form a welded portion (W), and the upper end of the outer peripheral surface of the closet outer wall 45 and the upper end of the side wall portion 11 of the battery can 10 are welded together to form a joint portion (M).

[0114] The outermost surface 44 is located further outward in the axial direction than the axial end 39 of the closet outer wall 45. In other words, the height of the outermost surface 44 is greater than the height of the closet outer wall 45. Therefore, even when the battery can 10 is placed upright with the cap 40 in contact with the ground while the joint (M) is formed between the closet outer wall 45 and the side wall portion 11, the joint (M) does not receive a load directly from the ground, thus protecting the joint (M).

[0115] Furthermore, the outermost surface 44 is in contact with the ground and receives loads, and these loads act axially, pressing the electrode connecting portion 41 and the tabs of the second electrode 22 together, thus protecting the welded portion (W) of the cap 40 and the notched tab 27.

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

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

[0118] Compared to the first embodiment, the cap 40 of the third embodiment is further provided with a liquid injection port 42 in the center of the cap 40. The liquid injection port 42 can be aligned with the hollow portion of the core of the electrode assembly 20.

[0119] The liquid injection port 42 can be provided on a central protruding region of the cap 40, such as a circular protrusion 43 that protrudes slightly above the electrode connecting portion 41 of the cap 40. The height of the protrusion 43 is set lower than the height of the outermost surface 44. When the liquid injection port 42 is covered and closed by a stopper 50, which will be described later, the height of the stopper 50 may also be lower than the height of the outermost surface 44.

[0120] Since the protruding portion 43 protrudes higher than the bottom of the cap 40, when the stopper 50 is covered and joined by welding or other means after the electrolyte is injected through the injection port 42, preferably the heat for joining is not transferred to the electrode assembly 20, reducing the risk of damaging the separation membrane.

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

[0122] However, as in the third embodiment, if the cap 40 is provided with a liquid injection port 42, the electrolyte can be injected through the liquid injection port 42 even after the cap 40 has been assembled onto the battery can 10 and the welded portion (W) and joint portion (M) have been formed. Compared to joining the cap 40 to the battery can 10 which has already been injected with electrolyte, the third embodiment, which is equipped with a liquid injection port 42, has the advantage of reducing the effect of joining heat on the electrolyte. Furthermore, even when joining the stopper 50 and the area around the liquid injection port 42, the protruding portion 43 protrudes upward so as to be far from the inside of the battery can, thus reducing the possibility that the joining heat of the stopper 50 will affect the electrolyte.

[0123] Since the plug 50 is positioned lower than the outermost surface 44, the plug 50 does not bear any direct load even when the battery cell is upright with the cap 40 in contact with the ground.

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

[0125] In other words, as shown in Figure 30, the electrode assembly 20 can be housed in the battery can 10 with the current collector plate 31 attached to the tab of the first electrode 21 and the cap 40 attached to the tab of the second electrode 22. The welding of the current collector plate 31 and the first electrode terminal 13 can be performed through the liquid injection port 42 of the cap 40 and the hollow core portion of the electrode assembly 20.

[0126] [Fourth embodiment] In the following, with reference to Figures 31 to 35, a fourth embodiment of the cap and the structure of a battery cell to which it is applied will be described.

[0127] Similar to the relationship between the third embodiment and the first embodiment, the cap 40 of the fourth embodiment also has a liquid injection port 42 in the center compared to the second embodiment. Furthermore, the cap of the fourth embodiment has a shape in which the radially inner side of the intermediate region 49 of the cap 40 is separated radially outward from the protruding portion 43 by the annular portion 55 of the cap 40. As a result, both the radially inner and outer sides of the intermediate region 49 can have an arc shape.

[0128] A vent 60 having the shape of a weak or thin portion is provided along the bottom of the annular projection 48 of the cap 40. The vent 60 can be provided by forming notches on both sides or one side of the upper and bottom surfaces of the annular projection 48. The vent 60 is provided radially outward from the electrode connecting portion 41 and may extend along the circumferential direction.

[0129] Preferably, the vent 60 has sufficient strength to withstand the force applied when the cap 40 is pressed into the battery can 10 without deforming. On the other hand, when the internal pressure increases rapidly due to a short circuit or the like inside the battery can 10, the vent 60 may break, separating the electrode connecting portion 41 of the cap 40 from the outer wall 45 of the cap 40. This breaks the electrical connection between the electrode connecting portion 41, which is connected to the tab of the second electrode 22, and the battery can 10, opening the internal space of the battery can 10 to the outside and releasing the gas that caused the pressure buildup.

[0130] Furthermore, the vent 60 is provided radially outward from the intermediate region 49 of the cap 40 on which the outermost surface 44 is provided. As described above, these outermost surfaces 44 are positioned on the intermediate region 49 of the cap 40, which is provided between the electrode connecting portions 41 in the circumferential direction.

[0131] Therefore, when the pressure resistance of the battery can 10 increases, these pressures act on the bottom surface of the cap 40, forcibly pushing upward the portion of the cap 40 located radially inward of the vent 60. The action of these forces is concentrated in four circumferential regions (for example, on the bottom surface of the intermediate region 49 provided between the circumferential electrode connecting portion 41). Thus, the pressure resistance of the battery can 10 is smoothly transmitted to the vent 60, causing the vent 60 to rupture smoothly.

[0132] In the fourth embodiment, the vent 60 is positioned radially inside the recessed outer wall 45 of the cap 40, and radially outside the electrode connecting portion 41 and the intermediate region 49 between them.

[0133] However, the vent 60 formed by the cap 40 is not limited to this. For example, the vent may be provided on the stopper 50 that covers the liquid injection port 42, or it may be formed at the joint between the liquid injection port 42 and the stopper 50, or it may be formed at the joint (M) between the cap 40 and the battery can 10. In other words, according to the embodiment, by realizing the vent structure in the cap 40 itself or at the joint between the cap 40 and other parts, it is possible to avoid separately allocating volume for the vent structure. This makes it possible to further increase the energy density of the battery cell.

[0134] [Fifth Example] The fifth embodiment of the cap will be described below with reference to Figures 36 to 38.

[0135] The cap of the fifth embodiment differs from that of the fourth embodiment in that the protrusion 43 providing the liquid injection port 42 is directly adjacent to or directly connected to the radially inner portion of the intermediate region 49, which is positioned between the electrode connecting portions 41 in the circumferential direction.

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

[0137] On the other hand, in the fifth embodiment, as shown in Figure 37, the cap 40 has a projection 43 that is directly connected to the intermediate region 49 of the cap 40. This structure defines the heat conduction path so that when heat is generated during welding of the stopper 50 to finish the liquid injection port 42, the heat is not substantially conducted to the electrode assembly but is conducted to the intermediate region 49. Thus, the adverse effects of the joining heat on the electrode assembly 20 can be further reduced.

[0138] Furthermore, as is also the case in the above embodiment, as shown in Figure 38, the electrode connecting portion 41 has intermediate regions 49 adjacent to both sides in the circumferential direction. Therefore, the heat generated when welding the electrode connecting portion 41 to the tab 27 of the second electrode 22 can be dissipated through the outermost surface 44 of the intermediate region 49. Thus, the adverse effects of bonding heat on the electrode assembly 20 can be further reduced.

[0139] [Method for manufacturing battery cells] The cap 40 in the above-described embodiment retains its original function as a cap while also functioning as a current collector plate for the second electrode. Therefore, its manufacturing method differs from conventional methods for manufacturing battery cells equipped with a current collector plate for the second electrode.

[0140] Furthermore, in embodiments of the present invention in which the cap 40 is equipped with an injection port 42, and these injection ports 42 can be used as passages for the joining process between the current collector plate 31 and the first electrode terminal 13, the method for manufacturing a battery cell can be configured even more flexibly.

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

[0142] This includes the steps of preparing a battery can 10 with the first electrode terminal 13 fixed to it, and preparing an electrode assembly comprising the first electrode and the second electrode. The first electrode and the current collector can be joined and connected at one axial end of the electrode assembly.

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

[0144] Next, electrolyte is poured into the battery container 10 through the open end of the battery container 10.

[0145] Next, the open end of the battery can 10 is covered and shielded with the cap 40. Preferably, the electrode connecting portion 41 of the cap 40 and the tab of the second electrode 22 of the electrode assembly 20 are joined in close contact. Then, the area around the open end of the battery can 10 and the edge of the cap 40 are joined.

[0146] According to these manufacturing methods, there is no need for separate joining work of the current collector plate for the second electrode 22.

[0147] Next, a manufacturing method relating to the flowchart in Figure 40 will be described. This can be applied, for example, when the cap 40 is equipped with a liquid injection port 42.

[0148] This includes the steps of preparing a battery can 10 with the first electrode terminal 13 fixed to it, and preparing an electrode assembly comprising the first electrode and the second electrode. The first electrode and the current collector can be joined and connected to one axial end of the electrode assembly.

[0149] Next, the electrode assembly 20 is inserted into the battery can 10 so that the current collector faces the bottom 12 of the battery can 10, and the current collector plate 31 of the electrode assembly 20 is joined to the first electrode terminal 13 fixed to the bottom 12 of the battery can 10 by welding or other means.

[0150] Next, the open end of the battery can 10 is covered and shielded with the cap 40. Preferably, the electrode connecting portion 41 of the cap 40 and the tab of the second electrode 22 of the electrode assembly 20 are joined in close contact. Then, the area around the open end of the battery can 10 and the edge of the cap 40 are joined.

[0151] Next, electrolyte is poured into the battery can 10 through the liquid injection port, and the liquid injection port 42 is sealed with the stopper 50 to complete the process.

[0152] According to these manufacturing methods, a separate current collector plate joining process is unnecessary for the second electrode 22. Moreover, the joining of the cap 40 to the second electrode 22 and the joining of the cap 40 to the battery can 10 can be performed before filling the battery can 10 with electrolyte. As a result, it is possible to prevent the joining heat from affecting the electrolyte.

[0153] Next, another manufacturing method relating to the flowchart in Figure 41 will be described. This can be applied, for example, when the cap 40 is equipped with a liquid inlet 42.

[0154] This includes the steps of preparing a battery can 10 with the first electrode terminal 13 fixed to it, and preparing an electrode assembly comprising the first electrode and the second electrode. The first electrode and the current collector can be joined and connected to one axial end of the electrode assembly. The electrode connecting portion 41 of the cap 40 and the tab of the second electrode can be joined and connected to the other axial end of the electrode assembly.

[0155] In other words, the cap can be joined to the second electrode of the electrode assembly before the electrode assembly is housed in the battery case.

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

[0157] Next, the current collector plate 31 of the electrode assembly 20 is joined to the first electrode terminal 13 fixed to the bottom 12 of the battery can 10 by welding or other means. Then, the area around the open end of the battery can 10 and the edge of the cap 40 are joined together.

[0158] Next, electrolyte is poured into the battery can 10 through the liquid filling port 42 of the battery can 10, and the liquid filling port 42 of the battery can 10 is sealed with a stopper 50 to complete the process.

[0159] According to this manufacturing method, there is no need for separate joining of the current collector plate for the second electrode 22. Furthermore, the joining of the cap 40 to the second electrode 22 and the joining of the cap 40 to the battery can 10 can be performed before filling the inside of the battery can 10 with electrolyte. This prevents the joining heat from affecting the electrolyte. In addition, the cap 40 can be integrated into the electrode assembly 20 beforehand without separate management, further simplifying the assembly equipment.

[0160] [Battery pack and vehicle] Referring to Figure 42, the battery cell 72 to which the aforementioned cap is applied and / or the battery cell 72 to which the aforementioned manufacturing method is applied can be housed in the housing 71 of the battery pack 70. The battery pack 70 can also be constructed using battery modules, which are an intermediate form of assembly, or, as shown in the figure, the battery pack 70 can be constructed directly without battery modules.

[0161] Because the aforementioned battery cell 72 has a large volume on its own, there is no particular difficulty in manufacturing the battery pack 70 without using an intermediate structure called a battery module. Furthermore, since the second electrode of the battery cell 72 is connected via a cap, it has low internal resistance and a higher energy density. Therefore, a higher energy density can be realized in the battery pack 70.

[0162] Thus, a battery pack 70 with increased energy density can store the same amount of energy while reducing its volume and weight. Therefore, when a battery pack 70 to which these battery cells 72 are applied is installed in a vehicle such as an electric automobile 80, as shown in Figure 43, the vehicle's energy mileage can be further extended.

[0163] The embodiments described above should be understood to be illustrative and not limiting in all respects, and the scope of the present invention is indicated more by the claims described below than by the detailed description above. The meaning and scope of the claims described below, as well as any modifications and deformable forms conceived from their equivalent concepts, should be interpreted as being included within the scope of the present invention.

[0164] As described above, the present invention has been explained with reference to the illustrative drawings. However, the present invention is not limited to the embodiments and drawings disclosed herein, and it is obvious to an ordinary person skilled in the art that various modifications can be made 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 embodiments of the present invention are described above, it is natural to acknowledge that predictable effects can be obtained from such configuration.

Claims

1. A battery can including a side wall portion extending axially between a closed first end and an open second end, wherein the open second end defines an opening inside the battery can; An electrode assembly comprising a first electrode and a second electrode, which is housed inside the battery can, wherein at least one tab extending from the second electrode is positioned near the open second end of the battery can; and A cap positioned to cover the opening at the second end, thereby closing the open second end of the battery can; Includes, The cap includes a plurality of electrode connecting portions that protrude axially into the battery can so as to be in direct electrical contact with at least one tab of the second electrode, The multiple electrode connecting portions are arranged circumferentially, spaced apart from each other with respect to the center of the cap. At least two electrode connecting portions are arranged on opposite sides of the center of the cap, Multiple electrode connecting portions are connected to each other by protrusions of the cap in the radial central region of the cap. The protruding portion of the cap is a battery cell that protrudes axially into the interior of the battery can.

2. A battery can including a side wall portion extending axially between a closed first end and an open second end, wherein the open second end defines an opening inside the battery can; An electrode assembly comprising a first electrode and a second electrode, which is housed inside the battery can, wherein at least one tab extending from the second electrode is positioned near the open second end of the battery can; and A cap positioned to cover the opening at the second end, thereby closing the open second end of the battery can; Includes, The cap includes a plurality of electrode connecting portions that protrude axially into the battery can so as to be in direct electrical contact with at least one tab of the second electrode, The multiple electrode connecting portions are arranged circumferentially, spaced apart from each other with respect to the center of the cap. At least two electrode connecting portions are arranged on opposite sides of the center of the cap, The multiple electrode connecting portions are connected to each other by protrusions of the cap that extend around the radially outer region of the cap. The protruding portion of the cap is a battery cell that protrudes axially into the interior of the battery can.

3. A battery can including a side wall portion extending axially between a closed first end and an open second end, wherein the open second end defines an opening inside the battery can; An electrode assembly comprising a first electrode and a second electrode, which is housed inside the battery can, wherein at least one tab extending from the second electrode is positioned near the open second end of the battery can; and A cap positioned to cover the opening at the second end, thereby closing the open second end of the battery can; Includes, The cap includes a plurality of electrode connecting portions that protrude axially into the battery can so as to be in direct electrical contact with at least one tab of the second electrode, The multiple electrode connecting portions are arranged circumferentially, spaced apart from each other with respect to the center of the cap. At least two electrode connecting portions are arranged on opposite sides of the center of the cap, The cap includes a liquid injection port provided in the center of the cap, The liquid injection port is located in the central protruding region of the cap. The aforementioned central protruding region is positioned further outward in the axial direction from the inside of the battery can than the contact surfaces of each of the multiple electrode connecting portions. The contact surface is in direct electrical contact with at least one tab of the second electrode. Between the electrode connecting portions, which are spaced apart in the circumferential direction, the intermediate region of the cap is defined. The intermediate region of the cap is positioned further outward in the axial direction from the inside of the battery can than the contact surface of the electrode connecting portion. The central protruding region of the cap is positioned closer to the interior of the battery can in the axial direction than the central protruding region and the intermediate region, and the battery cell is positioned radially away from the intermediate region by the outer surface of the cap.

4. Multiple electrode connecting portions and at least one tab of the second electrode are connected by a welded portion. A battery cell according to any one of claims 1 to 3.

5. The at least one tab includes a plurality of tabs extending radially perpendicular to the axial direction, and the plurality of tabs overlap each other at least partially in the axial direction. A battery cell according to any one of claims 1 to 3.

6. Each of the multiple electrode connections extends along the radial direction of the cap, A battery cell according to any one of claims 1 to 3.

7. The multiple electrode connecting portions include four electrode connecting portions spaced equally apart in the circumferential direction. A battery cell according to any one of claims 1 to 3.

8. Each of the multiple electrode connections extends linearly along its respective radial direction. The battery cell according to claim 7.

9. The cap comprises an electrically conductive material, and the electrically conductive material along the radial outer edge of the cap is in electrical contact with the side wall portion of the battery can at the second end. A battery cell according to any one of claims 1 to 3.

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

11. Each of the multiple electrode connecting portions is a recessed portion formed on the outer surface of the cap. The battery cell according to claim 10.

12. The cap includes a liquid inlet provided in the center of the cap. The battery cell according to claim 1 or 2.

13. The liquid injection port is located in the central protruding region of the cap. The aforementioned central protruding region is positioned further outward in the axial direction from the inside of the battery can than the contact surfaces of each of the multiple electrode connecting portions. The contact surface is in direct electrical contact with at least one tab of the second electrode. The battery cell according to claim 12.

14. Between the electrode connecting portions, which are spaced apart in the circumferential direction, the intermediate region of the cap is defined. The intermediate region of the cap is positioned further outward in the axial direction from the inside of the battery can than the contact surface of the electrode connecting portion. The central protruding region of the cap is located further axially closer to the interior of the battery can than the central protruding region and the intermediate region, and is radially separated from the intermediate region by the outer surface of the cap. The battery cell according to claim 13.

15. Between the electrode connecting portions, which are spaced apart in the circumferential direction, the intermediate region of the cap is defined. The intermediate region of the cap is positioned further outward in the axial direction from the inside of the battery can than the contact surface of the electrode connecting portion. The central protruding region of the cap is directly adjacent to the intermediate region in the radial direction. The battery cell according to claim 13.

16. The aforementioned cap includes a vent. The vent is positioned radially outward from the plurality of electrode connecting portions. The battery cell according to claim 1.

17. The first electrode terminal is located at the closed first end of the battery can, and the first electrode terminal is electrically insulated from the closed first end of the battery can. The first electrode of the electrode assembly is electrically connected to the first electrode terminal via a first current collector plate positioned axially between the electrode assembly and the closed first end of the battery can. A battery cell according to any one of claims 1 to 3.

18. The cap is formed and positioned such that its outermost surface, which is axially positioned away from the inside of the battery can, is positioned even further axially from the inside of the battery can than the second end of the battery can. A battery cell according to any one of claims 1 to 3.

19. At least two of the electrode connecting portions are arranged on opposite sides of the center of the cap. The straight line connecting the two electrode connecting portions extends through the center of the cap. A battery cell according to any one of claims 1 to 3.

20. At least two of the electrode connecting portions extend radially, A battery cell according to any one of claims 1 to 3.

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

22. A method for manufacturing a battery cell according to any one of claims 1 to 3, Assembling a battery cell by positioning the electrode assembly inside the battery can, positioning the cap so as to cover the opening at the second end of the battery can, and closing the second end of the battery can; After assembling the battery cell, the plurality of electrode connecting portions are joined to at least one tab of the second electrode; Joining the cap to the battery can; and Pouring electrolyte into the aforementioned battery container; including, A method for manufacturing battery cells.

23. The electrolyte is poured into the battery case through the pouring port located in the center of the cap. A method for manufacturing a battery cell according to claim 22.

24. Cover the aforementioned injection port with a stopper; Further including, A method for manufacturing a battery cell according to claim 23.

25. Joining the multiple electrode connecting portions to at least one tab of the second electrode is done by irradiating the outer surface of the tab with a laser in a direction away from the inside of the battery can in the axial direction. A method for manufacturing a battery cell according to claim 22.

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

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

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