Battery cell, method for manufacturing battery cell, battery pack, and vehicle

Abstract

A battery cell, a method for manufacturing a battery cell, a battery pack, and a vehicle. A cylindrical battery cell includes a battery can, and a cap, in which a jellyroll-type electrode assembly is housed, the cap covering and closing the open end of the battery can. The cap is joined to a connector of an electrode of the electrode assembly. The cap includes two or more electrode connecting portions, each of which protrudes into the interior of the battery can in an axial direction. The electrode connecting portions are spaced apart from each other in a circumferential direction around the center of the cap, and at least two of the electrode connecting portions are positioned on opposite sides of the center of the cap. The cap serves as both a current collector plate and a cap, thereby increasing energy density. A manufacturing method is also disclosed, as is a battery pack including the battery cell and a vehicle equipped with the battery pack.

Description

Technical Field

[0001] The present invention relates to a cylindrical battery cell and a method for manufacturing the same, a battery pack including the same, and a vehicle including the same. Background Art

[0002] Cylindrical battery cells have a structure in which a jellyroll-type electrode assembly is housed inside a cylindrical metal can, which is more robust against impacts and high temperatures than pouch-type batteries. Consequently, demand for can-type cells as battery cells for battery packs in vehicles is increasing.

[0003] However, since the can is made of metal, the can-type cell may be heavier than the pouch-type battery. Therefore, research related to increasing the electrical capacity by increasing the internal volume of each battery can is being actively conducted.

[0004] The process of manufacturing a battery cell using a cylindrical can may include a can preparation operation, which deep-draws a metal sheet to form a circular bottom and a circular tubular sidewall connected to the circular bottom, and positions, insulates, and seals a first electrode terminal in the center of the circular bottom of the can. The process also includes an operation of preparing a jellyroll-type electrode assembly having opposite ends in an axial direction, with a first current collector plate and a second current collector plate respectively disposed at the opposite ends. The process also includes an assembly operation, which houses the electrode assembly in the can, connects the first current collector plate to the first electrode terminal, connects the second current collector plate to the can or cap, fills the interior of the can with electrolyte, and closes the open end of the sidewall with a cap to complete the manufacture of the battery cell.

[0005] In the cylindrical battery cell manufactured as described above, since the space for accommodating the second current collector plate must be provided inside the can, the volume of the electrode assembly is inevitably reduced by the same amount as the space, resulting in a decrease in energy density. In addition, the conventional process for manufacturing cylindrical battery cells includes an additional process of manufacturing the second current collector plate and connecting the second current collector plate to the second electrode of the electrode assembly, which increases the manufacturing cost of the battery cell. Summary of the Invention

[0006] The present invention can advantageously provide a battery cell in which reliability of electrical connection between electrodes of the electrode assembly and the electrode terminals of the battery can is still provided despite the omission of a current collector plate for connecting the electrode assembly to the electrode terminals of the battery can.

[0007] The present invention can also advantageously provide a battery cell that can reduce manufacturing costs by reducing the number of components and manufacturing man-hours and by being simple.

[0008] The present invention can also advantageously provide a battery cell that has high energy density and is advantageously mounted in a vehicle, and a battery pack and a vehicle including the battery cell.

[0009] One aspect of the present invention provides a battery cell. Such a battery cell advantageously comprises a battery can, an electrode assembly and a cap. The battery can preferably comprises a sidewall extending in an axial direction between a closed end and an opposite open end, wherein the open end defines an opening into the interior of the battery can. The electrode assembly preferably comprises two electrodes housed within the interior of the battery can such that at least one tab extending from a second of the electrodes is positioned proximate to the open end of the battery can. The cap is preferably positioned to close the open end of the battery by covering the opening. The cap preferably comprises a plurality of electrode connecting portions protruding into the interior of the battery can in an axial direction so as to be in direct electrical contact with at least one tab of the second electrode. Such electrode connecting portions are preferably spaced apart from each other in a circumferential direction around the center of the cap, and at least two of the electrode connecting portions are preferably positioned on opposite sides of the center of the cap.

[0010] According to at least some aspects of the present invention, the electrode connection portion and the joint(s) of the second electrode may be connected by a weld portion.

[0011] According to at least some aspects of the present invention, the at least one joint may include a plurality of joints extending in a radial direction orthogonal to the axial direction, such that the joints at least partially overlap one another along the axial direction.

[0012] According to at least some aspects of the present invention, each of the electrode connection portions may be elongated in a radial direction of the cap.

[0013] According to at least some aspects of the present invention, there may be four electrode connection portions spaced equidistantly in the circumferential direction. According to some such aspects, each of the electrode connection portions may be linearly elongated along a respective radial direction.

[0014] According to at least some aspects of the present invention, the electrode connection portions may be coupled to each other in a radially central region of the cap by a protruding portion of the cap that protrudes into the interior of the battery can in the axial direction.

[0015] According to at least some aspects of the present invention, the electrode connection portions may be coupled to each other by a protruding portion of the cap extending circumferentially around a radially outer region of the cap, the protruding portion protruding into the interior of the battery can in the axial direction.

[0016] According to at least some aspects of the present invention, the cap may include a conductive material that electrically contacts the sidewall of the battery can along a radially outer edge of the cap at the second end of the opening. The electrode connection portion may be integrally formed with the conductive material of the cap. In some examples, each of the electrode connection portions may correspond to a corresponding recess formed in an outer surface of the cap that faces away from the interior of the battery can in an axial direction.

[0017] According to at least some aspects of the present invention, the cap may include a liquid inlet in a central portion of the cap. Such a liquid inlet may be positioned on a central protruding region of the cap, which may be positioned further away from the interior of the battery can in the axial direction than a corresponding contact surface of each of the electrode connecting portions. Such a contact surface may be a contact surface that is in direct electrical contact with the contact(s) of the second electrode.

[0018] According to some of the above-mentioned aspects of the present invention, the middle region of the cap may be defined between the circumferentially spaced electrode connection portions. Such an middle region may be arranged to be further away from the interior of the battery can along the axial direction than the contact surface of the electrode connection portion. In some such aspects of the present invention, the central protruding region of the cap may be radially spaced apart from the middle region by a portion of the outer surface of the cap, the portion of the outer surface of the cap being arranged to be closer to the interior of the battery can along the axial direction than both the central protruding region and the middle region. In other such aspects of the present invention, the central protruding region of the cap may be directly adjacent to the middle region in the radial direction.

[0019] According to at least some aspects of the present invention, the cap may include a vent.Such a vent may be positioned radially outward from the electrode connection portion.

[0020] According to at least some aspects of the present invention, the first electrode terminal is positioned along the closed end of the battery can. Such an electrode terminal can be electrically insulated from the closed end of the battery can. In addition, the first electrode of the electrode assembly can be electrically connected to the first electrode terminal via a first current collector plate positioned axially between the electrode assembly and the closed end of the battery can.

[0021] According to at least some aspects of the present invention, the cap may be constructed and arranged so that an outermost end of the cap axially distal to the interior of the battery can may be axially spaced further from the interior of the battery can than an open end of the battery can.

[0022] According to at least some aspects of the present invention, at least two of the electrode connection portions may be positioned on opposite sides of the center of the cap such that a straight line connecting the at least two of the electrode connection portions will extend through the center of the cap.

[0023] According to at least some aspects of the present invention, the electrode connection portion can be elongated along a radial direction. Additionally, in some such aspects, the electrode connection portion can be elongated linearly along a line extending through the center of the cap.

[0024] Another aspect of the present invention provides a method for manufacturing a battery cell as described above. This method ideally includes assembling the battery cell, and then, after assembling the battery cell, joining the electrode connecting portion to at least one tab of the second electrode, joining the cap to the battery can, and injecting electrolyte into the battery can. Assembly of the battery cell preferably includes positioning the electrode assembly inside the battery can and positioning the cap to cover an opening at the open end of the battery can, thereby sealing the open end of the battery can.

[0025] According to at least some aspects of the above invention, the electrolyte can be injected into the battery can via a liquid inlet in the central portion of the cap. Some such aspects can also include covering the liquid inlet with a plug.

[0026] According to at least some aspects of the above invention, joining the plurality of electrode connecting portions to the at least one tab of the second electrode may be performed by laser irradiating the outer surface of the cap facing away from the interior of the battery can in the axial direction.

[0027] Other aspects of the present invention provide a battery pack including the battery unit described above, and a vehicle including such a battery pack.

[0028] According to some embodiments of the present invention, since the cap is directly electrically connected and fixed to the tab of the second electrode, and the cap is electrically connected and fixed to the sidewall of the can, the current collector plate can be omitted. Consequently, the energy density of the battery cell can be increased, the number of components of the battery cell can be reduced, and the manufacturing process can be simplified. Consequently, the manufacturing cost of the battery cell can be reduced.

[0029] According to some embodiments of the present invention, since the electrode connection portion of the cap connected to one or more tabs of the second electrode extends in the radial direction, the cap is electrically connected directly from the winding center of the second electrode to its periphery, so that the internal resistance can be significantly reduced.

[0030] According to some embodiments of the present invention, since the cap is provided with a plurality of electrode connecting portions extending in a radial direction, and each of the electrode connecting portions is recessed downward so that the (one or more) joints protrude into the interior of the battery can along the axial direction and toward the second electrode, the adhesion between each electrode connecting portion and the (one or more) joints of the second electrode can be ensured by a good quality joint therebetween.

[0031] This shape is believed to significantly improve the cap's resistance to deformation. Furthermore, it is believed this also increases the strength of the connection between the cap's perimeter and the open end of the battery can. Consequently, the quality of the bond between the battery can and the cap can be significantly improved.

[0032] According to some embodiments of the present invention, since the electrode connection portions of the cap are radially arranged at equal intervals in the circumferential direction, deformation resistance can be uniformly ensured in the circumferential direction, and current paths can be uniformly distributed.

[0033] According to some embodiments of the present invention, since a pair of electrode connecting portions facing each other across the center of the cap are aligned in a line, the shape of the fixture for press-fitting the cap into the battery can or pressing the cap against the electrode assembly can be simply achieved, and the trajectory of the welding line can be simplified.

[0034] According to some embodiments of the present invention, since the four electrode connectors are arranged at 90-degree intervals, the deformation resistance of the cap can be enhanced, the welding process can be simplified, and the bonding strength between the multiple electrode connection portions and the (one or more) joints of the second electrode can be increased. In addition, the location of plastic deformation of the cap is advantageously minimized, thereby reducing any degradation of the rigidity of the cap.

[0035] According to some embodiments of the present invention, the radially outer sides of the plurality of electrode connection portions may contact the inner circumferential surface of the battery can to provide a press-fit connection, which guides the cap to align with the center of the battery can. Thus, during press-fitting of the cap into the battery can, the center of the cap can naturally align with the battery can.

[0036] According to some embodiments of the present invention, since the press-fit depth of the cap is limited by the electrode connecting portion, the electrode connecting portion and the joint(s) of the second electrode can be joined with adhesion therebetween being sufficiently ensured.

[0037] According to some embodiments of the present invention, since the outermost surface of the cap is positioned axially above the joint portion that combines the cap and the battery can, such joint portion can be protected.

[0038] Then, when the battery can is properly placed, that is, when the outermost surface is placed on the floor, the outermost surface supports the load of the battery cell. In this case, the outermost surfaces positioned on both sides of each electrode connection portion in the circumferential direction have the effect of pressing the electrode connector toward the tab of the second electrode. Therefore, possible damage to the joint portion between the cap and the (one or more) tabs of the second electrode due to vibration or impact can be minimized.

[0039] The liquid inlet can be provided in the central portion of the cap, which can diversify the process of manufacturing the battery cell. In addition, by protruding the liquid inlet from the electrode connecting portion, any transfer of welding heat or joining heat to the electrode assembly when the liquid inlet is sealed with a plug can be minimized.

[0040] When the vent is positioned radially outside the electrode connection portion or weld, the cap region where the internal pressure of the battery acts can be more widely secured. This facilitates venting, and if the vent region is damaged by venting, electrical connection between the second electrode and the battery can be prevented. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The above and other objects, features and advantages of the present invention will become more apparent to those skilled in the art through the following detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings, in which:

[0042] Figure 1 is a perspective view showing a cylindrical battery cell according to an embodiment;

[0043] Figure 2 and Figure 3 are perspective views respectively showing states before and after lamination of a first electrode, a second electrode, and a separator for manufacturing an electrode assembly to be housed in a battery can;

[0044] Figure 4 It shows Figure 3 A plan view of the stacked state;

[0045] Figure 5 and Figure 6 They are shown by Figure 3 and Figure 4 A perspective view and a side view of an electrode assembly manufactured by winding a stack of layers into a core form;

[0046] Figure 7 and Figure 8 is a perspective view illustrating a state in which a current collector plate is joined to an upper portion of an electrode assembly and the current collector plate is not joined to a lower portion of the electrode assembly;

[0047] Figure 9 It shows that Figure 7 and Figure 8 A cross-sectional view showing a process in which an electrode assembly is housed in a battery can;

[0048] Figure 10 is a cross-sectional view illustrating a process of welding a first electrode terminal to a current collector plate;

[0049] Figure 11 is a cross-sectional view showing a process of placing a cap on a battery can;

[0050] Figure 12 is a cross-sectional view showing a state in which a cap is joined to a tab of a second electrode of an electrode assembly and the cap is joined to an edge of a battery can;

[0051] Figures 13 to 15 are a top perspective view, a bottom perspective view, and a plan view showing a cap according to a first embodiment, respectively;

[0052] Figure 16 It is along Figure 15 a cross-sectional view taken along line XVI-XVI of ;

[0053] Figure 17 It is along Figure 15 a cross-sectional view taken along line XVII-XVII;

[0054] Figure 18 is a cross-sectional view showing a process in which a battery can can be assembled using the cap according to the first embodiment;

[0055] Figures 19 to 21 are a top perspective view, a bottom perspective view, and a plan view showing a cap according to a second embodiment, respectively;

[0056] Figure 22 It is along Figure 21 a cross-sectional view taken along line XXII-XXII;

[0057] Figure 23 It is along Figure 21 a cross-sectional view taken along line XXIII-XXIII;

[0058] Figure 24 is a cross-sectional view showing a process in which a battery can is assembled using the cap according to the second embodiment;

[0059] Figure 25 and Figure 26 are a top perspective view and a plan view showing a cap according to a third embodiment, respectively;

[0060] Figure 27 It is along Figure 26 a cross-sectional view taken along line XXVII-XXVII;

[0061] Figure 28 and Figure 29 is a cross-sectional view showing a process in which a battery can is assembled using the cap according to the third embodiment;

[0062] Figure 30 is a perspective view showing a state in which a tab and a cap of a second electrode of an electrode assembly are first joined before the electrode assembly is housed in a battery can;

[0063] Figure 31 and Figure 32 are a top perspective view and a plan view showing a cap according to a fourth embodiment, respectively;

[0064] Figure 33 It is along Figure 32 a cross-sectional view taken along line XXXIII-XXXIII;

[0065] Figure 34 and Figure 35 is a cross-sectional view showing a process in which a battery can is assembled using the cap according to the fourth embodiment;

[0066] Figure 36 is a top perspective view showing a cap according to a fifth embodiment;

[0067] Figure 37 It is along Figure 36 a cross-sectional view taken along line XXXVII-XXXVII;

[0068] Figure 38 It is along Figure 36 a cross-sectional view taken along line XXXVIII-XXXVIII;

[0069] Figures 39 to 41 is a flow chart illustrating an embodiment of a method of assembling a battery cell using a cap according to an embodiment of the present invention; and

[0070] Figure 42 is a perspective view showing a battery pack using a battery cell according to an embodiment of the present invention; and

[0071] Figure 43 It is shown equipped with Figure 42 Diagram of the battery pack of a vehicle. DETAILED DESCRIPTION

[0072] The above objects, features and advantages will be described in detail below with reference to the accompanying drawings. In describing the present invention, detailed descriptions of known technologies related to the present invention are omitted where they may unnecessarily obscure the subject matter of the present invention. In the accompanying drawings, the same reference numerals are used to represent the same or similar parts.

[0073] Although "first", "second", etc. can be used to describe various components, these components are not limited by these terms. These terms are only used to distinguish one component from another component, and unless otherwise specified, the first component can be the second component, and vice versa.

[0074] Throughout the specification, unless otherwise specified, each component may be singular or plural. In addition, unless the context clearly indicates otherwise, the singular expressions used herein include the plural expressions.

[0075] Hereinafter, the arrangement of any component on the "upper portion (or lower portion)" or "upper (or lower)" of a component means that the component is placed in contact with the upper (or lower) surface of the component. In addition, this may mean that other components may be inserted between the component and any component disposed on (or below) the component.

[0076] In addition, when a component is described as being “linked,” “coupled,” or “connected” to another component, the components may be directly connected or connected to each other, but other components may be “interposed” between the respective components, or the respective components may be “linked,” “coupled,” or “connected” through other components.

[0077] Throughout the specification, when “A and / or B” is stated, it means A, B, or A and B unless otherwise specified; and when a range of “C to D” is stated, it means C or more and D or less unless otherwise specified.

[0078] In describing the embodiments, the axial direction refers to the direction in which the axis of the winding center constituting the jellyroll-type electrode assembly extends, the radial direction refers to the direction toward or away from the axis, and the circumferential direction refers to the direction along the periphery of a circle centered on and surrounding the axis.

[0079] The width direction of the electrode assembly before being wound into the winding core corresponds to the axial direction of the winding core. The length direction of the electrode assembly before being wound into the winding core corresponds to the circumferential direction of the winding core.

[0080] In the following, reference will be made to Figures 1 to 8 The structure of a cylindrical battery cell according to an embodiment of the present invention is described.

[0081] The shape factor of a battery cell refers to a value indicating the diameter and height of a cylindrical battery cell. A cylindrical battery cell according to an embodiment of the present invention may be, for example, a 46110 cell, a 48750 cell, a 48110 cell, a 48800 cell, or a 46800 cell. In the numerical value indicating the shape factor, the first two digits indicate the diameter of the cell in mm, the next two digits indicate the height of the cell in mm, and the last digit ('0') indicates that the cross-section of the cell is circular.

[0082] The battery cell according to an embodiment of the present invention may be a cylindrical battery cell having a substantially cylindrical shape, a diameter of about 46 mm, a height of about 110 mm, and a shape factor ratio of 0.418.

[0083] A battery cell according to another embodiment may be a cylindrical battery cell having a diameter of about 48 mm, a height of about 75 mm, and a form factor ratio of 0.640.

[0084] A battery cell according to another embodiment may be a generally cylindrical battery cell having a diameter of about 48 mm, a height of about 110 mm, and a form factor ratio of 0.418.

[0085] A battery cell according to another embodiment may be a generally cylindrical battery cell having a diameter of about 48 mm, a height of about 80 mm, and a form factor ratio of 0.600.

[0086] A battery cell according to another embodiment may be a cylindrical battery cell having a substantially cylindrical shape, a diameter of about 46 mm, a height of about 80 mm, and a form factor ratio of 0.575.

[0087] Conventionally, battery cells with a form factor ratio of approximately 0.4 or less have been used. Specifically, conventionally, 18650 cells, 21700 cells, and the like have been used. The 18650 cell has a diameter of approximately 18 mm, a height of approximately 65 mm, and a form factor ratio of 0.277. The 21700 cell has a diameter of approximately 21 mm, a height of approximately 70 mm, and a form factor ratio of 0.300.

[0088] The battery can 10 includes a cylindrical sidewall 11 extending in an axial direction between a closed first end and an open second end, wherein the closed first end is defined by a bottom 12 connected to an end portion of one side of the sidewall 11 in the axial direction.

[0089] A hole may be formed in the center portion of the bottom 12, and the first electrode terminal 13 may be fitted into and coupled to the hole. The first electrode terminal 13 may be riveted and fixed to the bottom 12 with the terminal gasket 14 inserted therebetween. The terminal gasket 14 may be inserted between the first electrode terminal 13 and the bottom 12 and may seal the interior and exterior of the battery can 10 to prevent leakage of the electrolyte and electrically insulate the first electrode terminal 13 from the bottom 12.

[0090] However, the connection method between the first electrode terminal 13 and the bottom 12 is not limited thereto. For example, various other fixing methods, such as a bolt-nut coupling method, a glass sealing method, and a maleic anhydride grafted polypropylene (PP-MAH) thermal bonding method, may be used, in which a structure forms a seal between the first electrode terminal 13 and the bottom 12 and also electrically insulates the first electrode terminal 13 from the bottom 12.

[0091] The first electrode terminal 13 may have a first polarity, and the battery can 10 may have a second polarity. Therefore, both the bottom 12 of the battery can 10 and the sidewall 11 connected to the bottom 12 may have the second polarity. Therefore, the bottom 12 surrounding the periphery of the first electrode terminal 13 may constitute the second electrode terminal 15, and the sidewall 11 connected to the bottom 12 may also constitute the second electrode terminal.

[0092] Then, both the first electrode terminal 13 and the second electrode terminal 15 may be provided at an end portion of one side of the battery can 10 in the axial direction. Then, in the battery can 10, both the bus bar connected to the first electrode terminal 13 and the bus bar connected to the second electrode terminal 15 may be positioned at an end portion of one side of the battery can 10 in the axial direction, for example, at the top of the battery can 10.

[0093] In one example, the first electrode terminal 13 may be a positive electrode terminal, and the second electrode terminal 15 may be a negative electrode terminal. Of course, the reverse is also possible.

[0094] The electrode assembly 20 is housed in the interior of the battery can 10. The electrode assembly 20 is manufactured by preparing a first electrode 21, a second electrode 22, and a separator 28, which extend in a longitudinal direction with a predetermined width (eg, Figure 2 As shown), a laminate is formed by laminating components in the following order: a first electrode 21, a separator 28, a second electrode 22, and a separator 28, as shown Figure 3 and Figure 4 The stack is then wound around a winding center axis to form a core configuration.

[0095] The first electrode 21 may be a positive electrode, and the second electrode 22 may be a negative electrode. Of course, the reverse is also possible.

[0096] Each of the first electrode 21 and the second electrode 22 is manufactured in the form of an electrode sheet. 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 portion 25 coated with the active material layer 24 and an uncoated portion 26 not coated with the active material layer 24. The positive electrode sheet is provided with the uncoated portion 26 on one side along the width direction, and the negative electrode sheet is provided with the uncoated portion 26 on the opposite side along the width direction.

[0097] In the stack, the uncoated portion 26 is exposed or protrudes in the width direction. The uncoated portion 26 itself serves as an electrode tab. Although the electrode "tab" used herein may be an integral part of the metal foil 23 protruding outward from the electrode assembly 20, such a "tab" may also be a separately formed conductive component that is securely and electrically connected to the current collecting metal foil 23 of the electrode.

[0098] The notched joint 27 shaped like a flag may be formed by forming notches at predetermined intervals in the uncoated portion 26 .

[0099] In some embodiments, the notched tabs 27 may each have an isosceles trapezoidal shape. However, the notched tabs 27 may have various shapes such as a semicircle, a semi-ellipse, a triangle, a rectangle, and a parallelogram.

[0100] In addition, in some embodiments, the notch joints 27 may be arranged along the length direction and have the same width as each other. However, the width of the notch joints 27 may be gradually or stepwise widened from the winding center to the periphery.

[0101] Additionally, in some embodiments, the notch joint 27 may have a height that gradually increases from the center of the winding to the periphery. However, the height of the notch joint 27 may alternatively be constant or gradually decrease.

[0102] In the electrode assembly 20 in the form of a jellyroll, the notch tab 27 may be bent radially inward or outward in the radial direction. Figure 5 and Figure 6 shown.

[0103] The notch tabs 27 may be bent one by one during the process of winding the stack to form the electrode assembly 20 having the jellyroll configuration. Alternatively, the notch tabs 27 may be bent all at once after the electrode assembly is wound into the jellyroll configuration.

[0104] In this way, as Figure 6 As shown, the notch joints 27 of the first electrode 21 and the notch joints 27 of the second electrode 22 bent and overlapped in the radial direction may define planes substantially perpendicular to the axial direction at both ends of the electrode assembly 20 along the axial direction.

[0105] like Figure 7 As shown, the current collector plate 31 may be joined to a substantially flat surface defined by radially curved notched tabs 27 exposed at both ends of the electrode assembly 20 .

[0106] The current collector plate 31 may be manufactured by stamping, trimming, perforating, and / or bending a metal sheet.

[0107] Reference Figure 7The current collector plate 31 includes one or more terminal connector portions 32 extending radially from a central portion of the current collector plate 31, an annular portion 33 circumferentially interconnecting radially outer ends of the terminal connector portions 32, and one or more electrode connector portions 34 extending radially inward from the annular portion 33 but not connected to the terminal connector portions 32. The central portion of the terminal connector portion 32 covers at least a portion of the hollow portion of the winding center of the electrode assembly 20.

[0108] Before the electrode assembly 20 is inserted into the battery can 10 , the electrode connector portion 34 is joined to the notch tab 27 of the first electrode 21 of the electrode assembly 20 by laser welding or the like.

[0109] Reference Figure 8 , the current collector plate may not be connected to the notch tab 27 of the second electrode 22 of the electrode assembly 20 .

[0110] like Figure 9 and Figure 10 As shown, the electrode assembly 20 is housed in the battery can 10 in a state where the current collector plate 31 is aligned to face the bottom 12 of the battery can 10. In this case, the insulator 19 is inserted between the first current collector plate 31 and the bottom 12 of the battery can 10 to electrically insulate the first current collector plate 31 from the bottom 12.

[0111] In addition, the terminal connector portion 32 of the current collector plate 31 is joined to the first electrode terminal 13 by resistance welding, ultrasonic welding, or laser welding. The welding device 100 for welding the current collector plate 31 to the first electrode terminal 13 performs welding by axially approaching the inner surface of the center of the terminal connector portion 32 of the current collector plate 31 through the hollow portion of the winding center of the electrode assembly 20. Alternatively, the current collector plate 31 and the first electrode terminal 13 can be joined by brazing, soldering, or the like.

[0112] Reference Figure 11 and Figure 12 , the notch tab 27 of the second electrode 22 can be directly connected to the cap 40 covering the opening defined by the open end of the battery can 10. The second electrode 22 is electrically connected to the cap 40 via a weld portion W between the cap 40 and the notch tab 27. Alternatively, the notch tab 27 and the cap 40 can be joined by brazing, soldering, or the like.

[0113] The cap 40 is formed of a conductive material. Alternatively, the cap 40 may be integrally formed of such a material. The edge of the cap 40 engages and electrically connects to the sidewall 11 of the battery can 10, securing and sealing the cap. Thus, the second electrode 22 can be electrically connected to the cap 40 and the battery can 10. Various methods capable of achieving electrical connection and sealing, such as welding, brazing, and soldering, can be used to join the cap 40 and the battery can 10.

[0114] Figure 11 and Figure 12 The cap 40 and the example of the assembly process thereof are shown for illustration purposes only. Hereinafter, various embodiments of the structure and assembly method of the cap 40 will be described. Although the joining portion described below is joined by welding, the present invention is not limited thereto.

[0115] [First embodiment]

[0116] In the following, reference is made to Figures 13 to 18 , a first embodiment of a cap and a structure of a battery cell in which the cap is used will be described.

[0117] The cap 40 can be made of a circular sheet of metal. The cap 40 includes one or more electrode connection portions 41 that are recessed in a direction corresponding to the axial direction of the battery cell 72. The electrode connection portions 41 can be formed by stamping, i.e., by pressing a metal sheet using a press and one or more forming dies. Therefore, due to this stamping, each protrusion defined by the electrode connection portion 41 on the underside of the cap 40 corresponds to a corresponding recess in the upper side of the cap.

[0118] The bottom of the electrode connecting portion 41 defines a corresponding contact surface that is in close contact with and bonded to the notch joint 27 of the second electrode 22 of the electrode assembly 20. The thickness of the electrode connecting portion 41, which is manufactured by pressing the metal sheet, is slightly less than the thickness of the metal sheet. Therefore, when the surface of the electrode connecting portion 41 is irradiated by the laser L, the localized heat generated by the laser can melt and bond the surfaces of the electrode connecting portion 41 and the notch joint 27 that are in contact with the bottom contact surface of the electrode connecting portion 41.

[0119] The electrode connecting portions 41 are provided as a plurality of protrusions protruding downward in the axial direction into the interior of the battery can 10. Figures 13 to 18 In the present embodiment shown, four electrode connecting portions 41 are radially formed by linearly elongating along corresponding radial directions. Such electrode connecting portions 41 are preferably equally spaced at equal intervals in the circumferential direction around the center 46 of the cap 40. In the case of four such electrode connecting portions 41, the intervals may be 90-degree intervals. In addition, the electrode connecting portions 41 may be joined to each other in the radial center region of the cap 40 so that the center region of the cap 40 also defines a protrusion protruding downwardly into the interior of the battery can 10 in the axial direction. Such a center protrusion may be formed to be at the same depth as the electrode connecting portions 41 and to be continuous with each of them. Thus, in the case of four equally spaced electrode connecting portions 41, such electrode connecting portions and the center protrusion joining them together define a cross shape, as shown in FIG. Figures 13 to 15 shown.

[0120] The welding portion W for joining one or more of the electrode connecting portions 41 to the notch joint 27 of the second electrode 22 of the electrode assembly 20 may have a linear shape formed along the radial direction to correspond to the extension direction of the corresponding electrode connecting portion 41. According to the present embodiment, the welding portion W having a linear, radially oriented extended shape may be formed for each of the plurality of electrode connecting portions 41.

[0121] The cap 40 provides an outermost surface 44, which is a surface that will contact the floor when the battery can 10 is placed upright so that the cap 40 of the battery can 10 faces the floor. Each outermost surface 44 is provided at a higher position than the electrode connecting portion 41 (i.e., farther from the interior of the battery can 10 in the axial direction) and is provided between two adjacent electrode connecting portions 41 in the circumferential direction.

[0122] Therefore, in a state where the electrode connecting portion 41 is brought into close contact with the notch joint 27 by pressing the outermost surface 44 in the axial direction using a jig, the electrode connecting portion 41 and the notch joint 27 can be welded together by irradiating the surface of the electrode connecting portion 41 with laser light. Then, since the pressure of the jig presses the electrode connecting portion 41 against the notch joint 27 on the opposite side of the weld line, welding can be performed reliably.

[0123] The pair of electrode connection parts 41 on opposite sides of the center 46 of the cap 40 have a shape in which the pair of electrode connection parts 41 are arranged along a straight line passing through the center 46 of the cap 40. Therefore, when forming a weld line, the weld line for two of the electrode connection parts 41 aligned along the line can be formed with only a single movement of the laser welding machine. When the first electrode connection part, the second electrode connection part, the third electrode connection part, and the fourth electrode connection part are sequentially arranged along the circumferential direction of the cap 40 of the first embodiment, the first electrode connection part and the third electrode connection part can be welded at once, and the second electrode connection part and the fourth electrode connection part can be welded at once.

[0124] Furthermore, according to this embodiment, when the outermost surface 44 between the first and third electrode connection portions is pressed using a jig, the cap 40 can behave as a rigid body without twisting or bending despite the pressure of the jig because the secondary moment of inertia created by the concave shapes of the second and fourth electrode connection portions is large. In fact, it is believed that by positioning at least two electrode connection portions 41 on opposite sides of the center 46 of the cap 40, the strength and rigidity of the cap 40 can be particularly effectively increased without increasing material and weight. In this regard, without being limited to a particular operating theory, it is believed that arranging such electrode connection portions 41 along a straight line extending through the center 46 of the cap is particularly advantageous, especially when such electrode connection portions extend along this line (and can even extend from the central region to opposite sides of the cap 40), because such an arrangement will define a portion of the cap structure similar to a reinforcing beam extending across the cap. Additionally, having four electrode connection portions 41 equally spaced about the center 46 so as to extend along two straight lines orthogonal to each other is believed to strengthen the cap even further, similar to vertical beams with moment resisting connections between them.

[0125] As described above, four electrode connection portions 41 are formed in the present embodiment so that all four electrode connection portions 41 can be welded via two laser scanning tracks.

[0126] When the number of electrode connection parts 41 is excessive, there is a problem that the strength of the cap 40 may be weakened. In addition, when only two or three electrode connection parts 41 are formed, it is difficult to create a cross section that provides sufficient secondary moment of inertia in the circumferential direction.

[0127] When the four electrode connection portions 41 are formed in a cross or "+" shape in the cap 40, as in this embodiment, the welding process can be performed accurately and conveniently, which can provide increased resistance to twisting and bending of the cap 40 and reduce or prevent the weakening of the cap 40 due to the pressing process. In addition, the cap 40 can not only function as a current collector plate, but also maintain the strength of its original function of closing the open end of the battery can 10.

[0128] The radially outer periphery of the cap 40 has a shape configured to be joined to the axial end of the side wall 11 at the open end of the battery can 10. To this end, the electrode connection portion 41 can be formed to be spaced radially inward from the outer periphery of the cap so that the lower surface of the cap 40 defines a base surface 47 having a circular contour extending around the center 46 of the cap 40 along the radially outer periphery. Figure 18As shown, the abutment surface 47 of the cap 40 can contact the axial end surface along the edge of the side wall 11 at the open end of the battery can 10, and these contact surfaces can be welded together by a laser guided radially inward along the outer periphery of the battery can 10 to form a joining portion M.

[0129] The radially outer sides of the electrode connection portions 41 may define press-fitting outer walls 45 having an outer diameter corresponding to the inner diameter of the battery can 10. Therefore, when the cap 40 is assembled to the battery can 10, the press-fitting outer walls 45 of the plurality of electrode connection portions 41 each come into contact with the inner peripheral surface of the battery can 10 and are press-fitted while sliding against the inner peripheral surface of the battery can 10, so as to guide alignment of the cap 40 relative to the battery can 10.

[0130] According to the first embodiment, the four press-fit outer walls 45 are evenly distributed in the circumferential direction and contact the battery can 10 over a portion of the entire periphery of the inner peripheral surface. Therefore, the cap 40 can be press-fitted into the battery can 10 relatively easily.

[0131] As described above, the cap 40 of the present embodiment has an advantage of easy assembly because the press-fit outer walls 45 are pressed together when the electrode connecting portion 41 is pressed.

[0132] In addition, according to the structure of the cap 40 in the present embodiment, since the laser used to weld the cap 40 to the battery can 10 is directed in the radial direction, if it is found that the base surface 47 of the cap 40 is not in close contact with the axial end surface of the side wall 11 in one or more areas, the laser will not be directed so that it will damage the electrode assembly 20 positioned inside the battery can 10.

[0133] According to the first embodiment, since even when Figure 18 When the battery can 10 is inverted and stood upright, the outermost surface 44 of the cap 40 is located further outward in the axial direction than the engaging portion M. Therefore, the engaging portion M does not directly contact the floor, making it easier to protect the engaging portion M.

[0134] When using the cap 40 described above, there is no need to use a current collector plate to electrically connect the second electrode 22 tab to the battery can 10. Consequently, the number of components and assembly man-hours can be reduced, and a larger internal volume can be created, thereby increasing energy density. Since 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 via the radially extending weld portion W, the current path is preferably evenly distributed, significantly reducing internal resistance.

[0135] [Second embodiment]

[0136] In the following, reference is made to Figures 19 to 24 Next, a second embodiment of a cap and the structure of a battery cell using the cap will be described. In describing the second embodiment, overlapping content with the first embodiment will be omitted. Therefore, content not described in one embodiment will be understood from the other embodiments. Furthermore, it will be readily understood that components of one embodiment may be substituted for, added to, or omitted from components of other embodiments.

[0137] The cap of the second embodiment differs from the cap of the first embodiment in that a protrusion portion in the form of an annular protrusion 48 extends along the radially outer peripheral region of the cap 40, with the annular protrusion 48 protruding downwardly in the axial direction into the interior of the battery can 10. The annular protrusion 48 connects the respective electrode connection portions 41. The radially outer periphery of the cap 40 is defined by the radially outer periphery of the annular protrusion 48, and the outer periphery of the annular protrusion 48 is configured to be positioned within the inner diameter of the sidewall 11 of the battery can 10. Thus, the radially outer periphery constitutes the press-fit outer wall 45.

[0138] The annular protrusion 48 may be formed simultaneously with the formation of one or more electrode connection portions 41. The outermost surface 44 of the cap 40 may be located on a middle region 49 of the cap 40 defined between the circumferentially spaced electrode connection portions 41 and radially inside the annular protrusion 48, and the cap 40 may have a shape in which the bottom of the annular protrusion 48 is connected to the bottom of the electrode connection portion 41. That is, the outermost surface 44 is located on the middle region 49 of the cap 40 that is positioned between the electrode connection portions 41 in the circumferential direction and radially inside the annular protrusion 48.

[0139] Different from the first embodiment, Figure 24 As shown, in the cap 40 of the second embodiment, the outer periphery of the press-fit outer wall 45 can contact the inner peripheral surface of the battery can 10 and can be press-fitted into the battery can 10. The press-fit outer wall 45 does not limit the press-fit depth of the cap 40 in the axial direction. In the second embodiment, the press-fit depth of the cap 40 can be limited by the electrode connection portion 41. That is, the cap 40 can be press-fitted to a position where the bottom of the electrode connection portion 41 is in close contact with the notch joint 27 of the electrode assembly 20.

[0140] In the above state, the electrode connecting part 41 and the recess joint 27 are welded along the length direction of the electrode connecting part, that is, welded in the radial direction to form a welding part W, and the upper end portion of the outer peripheral surface of the press-fit outer wall 45 and the upper end portion of the side wall 11 of the battery can 10 are welded to form a joining part M.

[0141] The outermost surface 44 is axially located above the axial end 39 of the press-fit outer wall 45. That is, the height of the outermost surface 44 is higher than the height of the press-fit outer wall 45. Therefore, in a state where the engaging portion M is formed on the press-fit outer wall 45 and the side wall 11, even when the battery can 10 is erected to allow the cap 40 to contact the floor, the engaging portion M does not directly receive a load from the floor, so that the engaging portion M can be protected.

[0142] In addition, since the outermost surface 44 contacts the floor to receive the load and applies the load in the axial direction in which the joint of the electrode connecting portion 41 and the second electrode 22 is pressed together, the weld portion W between the cap 40 and the notch joint 27 is also protected.

[0143] Since the cross section of the cap 40 of the second embodiment has a high second-order moment of inertia in the circumferential direction of the edge, it is strong in resistance to deformation and bending.

[0144] [Third embodiment]

[0145] In the following, reference is made to Figures 25 to 30 , a third embodiment of the cap and the structure of a battery cell using the cap will be described.

[0146] When compared with the first embodiment, the cap 40 of the third embodiment further includes a liquid inlet 42 provided at a central portion of the cap 40. The liquid inlet 42 may be aligned with a hollow portion of a winding center of the electrode assembly 20.

[0147] The liquid inlet 42 may be provided on a central protruding area of ​​the cap 40, such as a circular protrusion 43 that slightly protrudes upward from the electrode connection portion 41 of the cap 40. The height of the protrusion 43 is set to be lower than the height of the outermost surface 44. In a state where the liquid inlet 42 is covered and closed by a stopper 50 (which will be described below), the height of the stopper 50 may also be lower than the height of the outermost surface 44.

[0148] Since the protrusion 43 protrudes upward so as to be higher than the bottom of the cap 40, when the electrolyte is injected through the liquid inlet 42 and then the liquid inlet 42 is covered with the plug 50 and joined by welding, the heat used for joining is preferably not transferred to the electrode assembly 20, thereby reducing the risk of damaging the separator.

[0149] The cap 40 of the first and second embodiments described above is not provided with a separate liquid inlet. Therefore, when the cap 40 is positioned on the battery can 10 during the manufacture of those earlier embodiments, the electrolyte injection process can be performed first before covering the battery can 10 with the cap 40 because there is no separate liquid inlet in the battery can 10.

[0150] However, when the liquid inlet 42 is provided in the cap 40, as in the third embodiment, the electrolyte can be injected through the liquid inlet 42 even after the cap 40 is assembled to the battery can 10 and the welded portion W and the joined portion M are formed. Therefore, when compared to joining the cap 40 to the battery can 10 in a state where the electrolyte has already been injected, the third embodiment having the liquid inlet 42 may advantageously result in a reduction in any thermal effects on the electrolyte caused by the joining. Furthermore, even when the stopper 50 is joined to the periphery of the liquid inlet 42, since the protrusion 43 protrudes upward away from the interior of the battery can, the possibility of the joining heat applied to the stopper 50 affecting the electrolyte should be reduced.

[0151] Since the plug 50 is also positioned lower than the outermost surface 44 , the plug 50 does not directly receive a load even when the battery unit is erected with the cap 40 contacting the floor.

[0152] On the other hand, the liquid inlet 42 formed in the central portion of the cap 40 may be a passage through which equipment for welding the first electrode terminal 13 to the current collector plate 31 of the first electrode 21 may enter and exit. Figure 30 As shown, the cap 40 may first be attached to the battery can 10 in a state where it has been connected to the tab of the second electrode 22 of the electrode assembly 20. That is, as shown in FIG. Figure 30 As shown, the electrode assembly 20 can be housed in the battery can 10 in a state where the current collector plate 31 is bonded to the tab of the first electrode 21 of the electrode assembly 20 and the cap 40 is bonded to the tab of the second electrode 22. In addition, the process of welding the current collector plate 31 to the first electrode terminal 13 can be performed through the liquid inlet 42 of the cap 40 and the hollow portion of the winding center of the electrode assembly 20.

[0153] [Fourth embodiment]

[0154] In the following, reference is made to Figures 31 to 35 , a fourth embodiment of the cap and the structure of a battery cell using the cap will be described.

[0155] Similar to the relationship between the third embodiment and the first embodiment, the fourth embodiment is further provided with a liquid inlet 42 in the central portion of the cap 40, as compared to the second embodiment. In addition, as compared to the second embodiment, the cap of the fourth embodiment has a shape in which the radially inner side of the middle region 49 of the cap 40 is radially spaced outward from the protrusion 43 by the annular portion 55 of the cap 40. Therefore, both the radially inner side and the radially outer side of the middle region 49 can have an arcuate shape.

[0156] A vent 60 in the form of a weak or thin portion is positioned along the bottom of the annular protrusion 48 of the cap 40. The vent 60 may be formed by forming a recess in either or both of the upper and lower surfaces of the annular protrusion 48. The vent 60 is positioned radially outside each of the electrode connecting portions 41, where it may extend around the electrode connecting portion 41 in the circumferential direction.

[0157] The vent 60 preferably has sufficient strength so as not to deform due to any force applied when the cap 40 is press-fitted into the battery can 10. On the other hand, when the internal pressure increases rapidly due to a short circuit in the battery can 10, the vent 60 becomes disconnected to separate the electrode connection portion 41 of the cap 40 from its press-fit outer wall 45. As a result, the electrical connection between the battery can 10 and the electrode connection portion 41 of the tab connected to the second electrode 22 is disconnected, while also opening the internal space of the battery can 10 to the outside, thereby discharging the gas causing the internal pressure.

[0158] In addition, exhaust port 60 is provided radially outside middle region 49 of cap 40 where outermost surface 44 is located. In addition, as described above, outermost surface 44 is located on middle region 49 of cap 40 between electrode connecting portions 41 in the circumferential direction.

[0159] Therefore, when the internal pressure of the battery can 10 increases, the internal pressure is applied to the lower side of the cap 40, forcibly moving the portion of the cap 40 located radially inward of the vent 60 upward. This force acts strongly in the circumferential direction at four locations (i.e., on the lower side of the intermediate region 49 of the cap 40 located circumferentially between the electrode connecting portions 41). Therefore, the internal pressure of the battery can 10 can be smoothly transmitted to the vent 60, causing the vent 60 to rupture smoothly.

[0160] In the fourth embodiment, the vent 60 is provided radially inwardly of the press-fit outer wall 45 of the cap 40 and radially outwardly of the electrode connection portion 41 and the intermediate region 49 located between the electrode connection portions 41. However, the vent 60 formed in the cap 40 is not limited thereto. For example, the vent may be provided in the plug 50 covering the liquid inlet 42, may be formed in the joint between the liquid inlet 42 and the plug 50, or may be formed by the joint 24 between the cap 40 and the battery can 10. That is, according to this embodiment, by implementing the vent structure in the cap 40 or in the joint between the cap 40 and other components, it is possible to avoid providing a separate volume for the vent structure. Therefore, the energy density of the battery cell can be further improved.

[0161] [Fifth embodiment]

[0162] In the following, reference is made to Figures 36 to 38 , a fifth embodiment of the cap will be described.

[0163] The cap of the fifth embodiment differs from the fourth embodiment in that a protrusion 43 providing a liquid inlet 42 is directly adjacent to or connected to the radially inner side of an intermediate region 49 circumferentially positioned between the electrode connecting portions 41 .

[0164] Reference Figure 32 In the cap of the fourth embodiment, the protrusion 43 is surrounded by an annular portion 55 of the cap 40, which radially separates the protrusion 43 from the intermediate region 49. Figure 37 As shown, in the cap 40 of the fifth embodiment, the protrusion 43 is directly connected to the middle region 49 of the cap 40. Due to the above structure, when heat is generated during the welding of the plug 50 to close the liquid inlet 42, the heat conduction path is defined to transfer the heat directly to the middle region 49 without substantially conducting it to the electrode assembly 20. Therefore, any negative impact of the joining heat on the electrode assembly 20 can be advantageously reduced.

[0165] In addition, it should be noted that in all the above embodiments, Figure 38 As shown, since both sides of each electrode connecting portion 41 are adjacent to the middle region 49 in the circumferential direction, the heat generated when the electrode connecting portion 41 is welded to the tab 27 of the second electrode 22 is dissipated through the outermost surface 44 of the middle region 49. Therefore, any negative impact of the joining heat on the electrode assembly 20 can be advantageously reduced.

[0166] [Method of Manufacturing Battery Cell]

[0167] Since the caps 40 of the above embodiments each have the natural function of a cap while serving as a current collector plate for the second electrode, the method of manufacturing a battery cell is different from a conventional method of manufacturing a battery cell involving a conventional current collector plate for the second electrode.

[0168] Additionally, in embodiments of the present invention in which the cap 40 includes the liquid inlet 42 , the liquid inlet 42 may serve as a passage for the process of joining the current collector plate 31 to the first electrode terminal 13 , which may result in greater flexibility in the method of manufacturing battery cells.

[0169] First, combine Figure 39 This manufacturing method can be used when the cap 40 does not include a liquid inlet 42.

[0170] The manufacturing method includes preparing a battery can 10 to which a first electrode terminal 13 is fixed, and preparing an electrode assembly having a first electrode and a second electrode. The first electrode and a current collector may be connected and joined to one end of the electrode assembly in an axial direction.

[0171] Next, the electrode assembly 20 is inserted into the battery can 10 with the current collector facing the bottom 12 of the battery can 10 , and the current collector plate 31 of the electrode assembly 20 is joined (by welding, etc.) to the first electrode terminal 13 fixed to the bottom 12 of the battery can 10 .

[0172] Then, the electrolyte is injected into the battery can 10 through the open end of the battery can 10 .

[0173] Subsequently, the open end of the battery can 10 is closed by covering the open end of the battery can 10 with the cap 40. In this case, bonding is performed while the electrode connecting portion 41 of the cap 40 is in close contact with the joint (one or more) of the second electrode 22 of the electrode assembly 20. Then, the periphery of the open end of the battery can 10 is bonded to the periphery of the cap 40.

[0174] According to the above-described manufacturing method, a bonding process of a separate current collector plate for the second electrode 22 is not required.

[0175] Next, we will combine Figure 40 Another manufacturing method is described in the flowchart of FIG. This manufacturing method can be used when the cap 40 includes a liquid inlet 42 .

[0176] The manufacturing method includes preparing a battery can 10 to which a first electrode terminal 13 is fixed, and preparing an electrode assembly having a first electrode and a second electrode. The first electrode and a current collector may be connected and joined to one end of the electrode assembly in an axial direction.

[0177] Next, the electrode assembly 20 is inserted into the battery can 10 when 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 (by welding or the like) to the first electrode terminal 13, which is fixed to the bottom 12 of the battery can 10.

[0178] Subsequently, the open end of the battery can 10 is closed by covering the open end of the battery can 10 with the cap 40. In this case, bonding is performed while the electrode connecting portion 41 of the cap 40 is in close contact with the joint (one or more) of the second electrode 22 of the electrode assembly 20. Then, the periphery of the open end of the battery can 10 is bonded to the periphery of the cap 40.

[0179] Then, the electrolyte is injected into the battery can 10 through the liquid inlet, after which the liquid inlet is closed and sealed with the stopper 50 .

[0180] According to the above-described manufacturing method, a separate current collector plate bonding process is not required for the second electrode 22. In addition, the bonding between the cap 40 and the second electrode 22 and the bonding between the cap 40 and the battery can 10 can be performed before the inside of the battery can 10 is filled with electrolyte. Therefore, it is possible to prevent the bonding heat from affecting the electrolyte.

[0181] Next, we will combine Figure 41 The flowchart of FIG. 1 illustrates another manufacturing method. This manufacturing method can be applied to a case where the cap 40 is provided with a liquid inlet 42 .

[0182] The manufacturing method includes preparing a battery can 10 to which the first electrode terminal 13 is fixed, and preparing an electrode assembly having a first electrode and a second electrode. The first electrode and the current collector may be connected and joined to one end of the electrode assembly in the axial direction. In addition, the electrode connecting portion 41 of the cap 40 and the (one or more) joints of the second electrode may be connected and joined to the other axial end of the electrode assembly. That is, before the electrode assembly is housed in the battery can, the cap may first be joined to the second electrode of the electrode assembly.

[0183] Next, the electrode assembly 20 is inserted into the battery can 10 while the current collector faces the bottom 12 of the battery can 10. In the above process, the cap 40 moves to a position covering the open end of the battery can 10.

[0184] Next, the current collector plate 31 of the electrode assembly 20 is joined (by welding, etc.) to the first electrode terminal 13 fixed to the bottom 12 of the battery can 10. The periphery of the open end of the battery can 10 is then joined to the periphery of the cap 40.

[0185] Then, the electrolyte is injected into the battery can 10 through the liquid inlet 42 , and then the liquid inlet is closed and sealed with the plug 50 .

[0186] According to the above-described manufacturing method, a separate current collector plate bonding process for the second electrode 22 is not required. In addition, the bonding between the cap 40 and the second electrode 22, and the bonding between the cap 40 and the battery can 10, can be performed before the interior of the battery can 10 is filled with electrolyte. Therefore, the heat of the bonding can be prevented from affecting the electrolyte. In addition, the cap 40 is first integrated into the electrode assembly 20, eliminating the need to manage the cap 40 separately, thereby further simplifying the assembly equipment.

[0187] [Battery Pack and Vehicle]

[0188] Reference Figure 42, the battery cell 72 to which the above-described cap is applied and / or the battery cell 72 to which the above-described manufacturing method is applied can be housed in the housing 71 of the battery pack 70. The battery pack 70 can be formed using battery modules, each of which is an intermediate form of assembly, or as shown in the drawings, the battery pack 70 can be directly formed without battery modules.

[0189] Because the battery cells 72 themselves are relatively large, manufacturing the battery pack 70 without using an intermediate structure such as a battery module is not particularly difficult. Furthermore, since the second electrodes of the battery cells 72 are connected via the caps, internal resistance is low and energy density is high. Consequently, the resulting battery pack 70 is expected to achieve a higher energy density.

[0190] The battery pack 70 with increased energy density can store the same amount of energy while having a reduced volume and weight. Figure 43 As shown, when the battery pack 70 using the battery cells 72 is installed in a vehicle such as a vehicle 80 that uses electricity as an energy source, the energy of the vehicle can be further increased, thereby increasing the mileage of the vehicle.

[0191] It should be understood that the described embodiments are illustrative in all aspects and not restrictive, and the scope of the present invention will be indicated by the appended claims rather than the detailed description described. In addition, the meaning and scope of the appended claims and all changes and modifications derived from equivalent concepts should be interpreted as being included within the scope of the present invention.

[0192] Although the present invention has been described with reference to the exemplary drawings, it should be understood that the present invention is not limited to the embodiments and drawings disclosed in this specification, and it will be understood by those skilled in the art that various modifications are possible without departing from the scope and concept of the present invention. In addition, although all operational effects of the configuration according to the present invention are not explicitly described when describing the embodiments of the present invention, it should be understood that the predictable effects from the configuration are also recognized.

Claims

1. A battery cell, comprising: a battery can including a sidewall extending in an axial direction between a closed first end and an open second end, the open second end defining an opening into an interior of the battery can; an electrode assembly comprising a first electrode and a second electrode, the electrode assembly being received within the interior of the battery can such that at least one tab extending from the second electrode is positioned proximate the open second end of the battery can; as well as a cap positioned to close the open second end of the battery can by covering the opening at the second end, wherein the cap comprises a plurality of electrode connection portions protruding into the interior of the battery can along the axial direction so as to be in direct electrical contact with the at least one tab of the second electrode, The plurality of electrode connection portions are spaced apart from each other in a circumferential direction around the center of the cap, and, at least two of the electrode connection portions are positioned on opposite sides of a center of the cap relative to each other, wherein the plurality of electrode connection portions and the at least one joint of the second electrode are connected via a welding portion, wherein the plurality of electrode connection portions are coupled to each other in a radially central region of the cap through a protruding portion of the cap, wherein the cap comprises a liquid inlet in a central portion of the cap, and wherein the liquid inlet is positioned on a central protruding area of ​​the cap, the central protruding area being arranged to be further away from the interior of the battery can along the axial direction than a corresponding contact surface of each of the plurality of electrode connecting portions, the contact surface being in direct electrical contact with the at least one joint of the second electrode.

2. The battery cell according to claim 1, wherein The at least one joint includes a plurality of joints extending along a radial direction orthogonal to the axial direction, such that the plurality of joints at least partially overlap each other along the axial direction.

3. The battery cell according to claim 1, wherein Each of the plurality of electrode connection portions is elongated along a radial direction of the cap.

4. The battery cell according to claim 1, wherein The plurality of electrode connecting portions include four electrode connecting portions that are equally spaced apart in the circumferential direction.

5. The battery cell according to claim 4, wherein: Each of the plurality of electrode connection portions is linearly elongated along a corresponding radial direction. The battery cell according to claim 1 , wherein: The protruding portion of the cap protrudes into the interior of the battery can along the axial direction.

7. The battery cell according to claim 1, wherein: The protruding portion of the cap protrudes into the interior of the battery can along the axial direction.

8. The battery cell according to claim 1, wherein The cap includes a conductive material, and wherein the conductive material is in electrical contact with a sidewall of the battery can at the second end along a radially outer edge of the cap.

9. The battery cell according to claim 8, wherein: The plurality of electrode connection portions are integrally formed using the conductive material of the cap.

10. The battery cell according to claim 9, wherein Each of the plurality of electrode connecting portions corresponds to a corresponding recess formed in an outer surface of the cap facing away from the interior of the battery can in the axial direction.

11. The battery cell according to claim 1, wherein The middle region of the cap is defined between circumferentially spaced electrode connecting portions, the middle region of the cap is arranged to be further away from the interior of the battery can along the axial direction than the contact surfaces of the electrode connecting portions, and wherein the central protruding region of the cap is radially spaced from the middle region to a portion of the outer surface of the cap that is arranged to be closer to the interior of the battery can along the axial direction than the central protruding region and the middle region.

12. The battery cell according to claim 1, wherein The middle region of the cap is defined between circumferentially spaced electrode connecting portions, the middle region of the cap is arranged to be further away from the interior of the battery can along the axial direction than the contact surface of the electrode connecting portions, and wherein the central protruding region of the cap is directly adjacent to the middle region in the radial direction.

13. The battery cell according to claim 1, wherein: The cap includes a vent, and The exhaust port is positioned radially outward from the plurality of electrode connection portions.

14. The battery cell according to claim 1, wherein: A first electrode terminal is positioned along the closed first end of the battery can, the first electrode terminal being electrically insulated from the closed first end of the battery can, and The first electrode of the electrode assembly is electrically connected to the first electrode terminal via a first current collector plate positioned between the electrode assembly and the closed first end of the battery can in the axial direction.

15. The battery cell according to claim 1, wherein The cap is constructed and arranged so that an outermost end of the cap, which is away from the interior of the battery can in the axial direction, is spaced farther from the interior of the battery can in the axial direction than the second end of the battery can.

16. The battery cell according to claim 1, wherein At least two of the electrode connection portions are positioned on opposite sides of a center of the cap such that a straight line connecting at least two of the electrode connection portions extends through the center of the cap.

17. The battery cell according to claim 1, wherein At least two of the electrode connecting portions are elongated in a radial direction.

18. The battery cell according to claim 17, wherein: At least two of the electrode connection portions are linearly elongated along a straight line extending through a center of the cap.

19. A method for manufacturing a battery cell, the method comprising the steps of: assembling the battery cell according to claim 1 by positioning the electrode assembly inside the battery can and positioning the cap to cover the opening at the second end of the battery can, thereby closing the second end of the battery can; after assembling the battery cell, joining the plurality of electrode connecting portions to the at least one tab of the second electrode; engaging the cap to the battery can; as well as Electrolyte is injected into the battery can.

20. The method according to claim 19, wherein The electrolyte is injected into the battery can through the liquid inlet.

21. The method according to claim 20, further comprising the steps of: The liquid inlet was covered with a stopper.

22. The method according to claim 19, wherein The step of joining the plurality of electrode connecting portions to the at least one tab of the second electrode is performed by laser irradiating an outer surface of the cap facing away from the interior of the battery can in the axial direction.

23. A battery pack comprising the battery cell according to claim 1.

24. A vehicle comprising the battery pack according to claim 23.

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