Battery cell and method for manufacturing a battery cell

Abstract

The invention provides a welding structure of a battery tank, a collector plate and a cover, a welding method and a battery cell applying the welding structure and the welding method. The battery cell includes a can and an electrode assembly housed within the can. The can includes a bottom member, a side wall member connected to the bottom member so as to extend in an axial direction, and a cap configured to cover an open end provided at one axial end of the side wall member. The can connection portion is provided at an edge of a collector plate electrically connected to an electrode of the electrode assembly and is electrically connected to the can to abut against the can. The edge of the cover is welded and fixed. The welding includes: a plurality of first welding portions formed to be spaced apart from each other in a circumferential direction such that an edge of the open end side of the side wall member, an edge of the lid, and the can connection portion are welded together; and a second welding portion provided between the first welding portions such that at least an edge of the open end side of the side wall member and an edge of the cover are welded to the second welding portion. The first welded portions and the second welded portions are continuously formed while being alternately provided in the circumferential direction.

Description

Technical Field

[0001] The present disclosure relates to a battery cell and a method of manufacturing a battery cell.

[0002] The present disclosure relates to a battery cell, a battery pack including the battery cell, and a vehicle.

[0003] This application is based on and claims priority to Korean Patent Application No. 10-2023-0101856, filed with the Korean Intellectual Property Office on August 3, 2023, the disclosure of which is incorporated herein by reference in its entirety. In addition, this application is based on and claims priority to Korean Patent Application No. 10-2024-0102303, filed with the Korean Intellectual Property Office on August 1, 2024, the disclosure of which is incorporated herein by reference in its entirety. Background Art

[0004] The process of manufacturing a battery cell using a cylindrical can includes forming a circular bottom and a cylindrical sidewall member connected thereto by deep drawing using a metal sheet, storing an electrode assembly therein, and then covering and finishing an open end of the sidewall member with a lid.

[0005] Meanwhile, a current collector plate is provided at one of two axial ends of the electrode assembly opposite to the open end to be in electrical contact with an electrode tab of the electrode assembly. The current collector plate is connected to the lid or the sidewall member by welding or the like to be electrically connected to the lid or the sidewall member.

[0006] In the process of welding the current collector plate to the lid or the sidewall member, the current collector plate must be kept in close contact with the lid or the sidewall member. For this, a jig is required to bring the current collector plate and the lid or the current collector plate and the sidewall member into close contact, and in addition, a mask is required to expose a welding area.

[0007] In order to use the mask or the jig to bring the current collector plate into close contact with the lid or the sidewall member, a space for accommodating the mask or the jig must be provided inside the can. However, after removing the mask or the jig, the space remains empty, resulting in a problem that the internal space of the can is not effectively utilized. This hinders the design of increasing the energy density per unit volume of the can.

[0008] In addition, in order to close the open end of the cylindrical can, the process of electrically connecting the current collector plate to the lid or the sidewall member and the process of connecting the lid to the sidewall member are respectively performed. The increase in the number of such processes reduces the production efficiency of the cylindrical battery cell and increases the production cost.

[0009] Therefore, it is necessary to provide a method capable of effectively coupling the current collector plate to the can and effectively closing the open end of the can, and / or a method capable of achieving the efficiency of the welding process and the reliable strength of the welding when performing a welding process on components. Summary of the Invention

[0010] Technical problem

[0011] The present disclosure is designed to solve the problems of the related art, and thus the present disclosure aims to provide a welding structure of a battery can, a current collector plate, and a lid, and a battery cell applying the welding structure. The welding structure does not include a separate welding mask or fixture, thereby effectively utilizing the internal space of the can when welding the current collector plate disposed at the open end of the can, and enabling a design to increase the energy density per unit volume of the can.

[0012] According to another aspect, the present disclosure also aims to provide a welding structure of a battery can, a current collector plate, and a lid, and a battery cell applying the welding structure. The welding structure enhances the stability of the welding process by imparting the functions of a mask and a fixture to the can, the current collector plate, and the lid.

[0013] According to another aspect, the present disclosure also aims to provide a welding structure of a battery can, a current collector plate, and a lid, and a battery cell applying the welding structure. The welding structure integrates the process of welding the current collector plate to the can and the process of welding the lid to the sidewall member in a single welding process, thereby improving the production efficiency of the cylindrical battery cell and reducing the production cost.

[0014] According to another aspect, the present disclosure also aims to provide a welding structure of a can, a current collector plate, and a lid, and a battery cell applying the welding structure. The welding structure minimizes the generation of welding heat while welding the can, the current collector plate, and the lid together, thereby simplifying the assembly process of the current collector plate and the lid without adversely affecting the electrode assembly.

[0015] According to another aspect, the present disclosure also aims to provide a welding structure of a can, a current collector plate, and a lid, and a battery cell applying the welding structure. The welding structure can enhance the seal between the can and the lid while welding the can, the current collector plate, and the lid together.

[0016] According to another aspect, the present disclosure also aims to provide a welding structure of a can, a current collector plate, and a lid, and a battery cell applying the welding structure. The welding structure can ensure weldability, increase the stability of the process, and guarantee the durability of the welding.

[0017] According to another aspect, the present disclosure also aims to provide a welding structure of a can, a current collector plate, and a lid, and a battery cell applying the welding structure. The welding structure can perform stable and rapid welding while welding the can, the current collector plate, and the lid together, so as to be suitable for mass production.

[0018] The technical problems to be solved by the present disclosure are not limited to the above problems, and other objects and advantages of the present disclosure not mentioned above will be understood from the following description and will be more clearly understood through the embodiments of the present disclosure. In addition, it will be readily understood that the objects and advantages of the present disclosure can be achieved by the means shown in the appended claims and their combinations.

[0019] Technical solution

[0020] The above technical problems can be solved by forming a first welded portion (triple welded portion) and a second welded portion (double welded portion). In the first welded portion, the can, the current collector plate, and the lid are intermittently or partially welded together during a seam welding process for sealing the can. In the second welded portion, at least the can and the lid are welded together in the remaining seam welding section.

[0021] This can be achieved by irradiating a laser beam in a scanning manner to form the second welded portion so as to seam weld at least the can and the lid along the abutting portion extending in the circumferential direction between the can and the lid, and triple welding the can, the current collector plate, and the lid together in a section of the first welded portion using a different energy density and / or scanning speed of the laser from that in the section of forming the second welded portion.

[0022] Therefore, while maintaining the simplicity of the welding process of the can, the current collector plate, and the lid, the generation of excessive welding heat can be suppressed and the can can be reliably sealed.

[0023] Control of the energy density or the scanning speed can be performed to maintain the consistency of the generation, expansion, and solidification of the molten pool, so that the expansion of the molten pool can proceed smoothly even at the boundary between the first welded portion and the second welded portion.

[0024] Thus, seam welding can be continuously performed, and the expansion of the molten pool can proceed smoothly only in the section where triple welding is required for electrical connection to the electrode, thereby changing the welding range. Accordingly, the consistency of the generation, expansion, and solidification of the molten pool is maintained during the expansion process of the molten pool, and the expansion of the molten pool can proceed smoothly, achieving reliable sealing without any defects.

[0025] The present disclosure for solving the above problems can be applied to a battery cell, which includes an electrode assembly, a current collector plate electrically connected to the electrode assembly, and a can for accommodating the electrode assembly and the current collector plate.

[0026] The can includes a bottom member, a side wall member connected to the bottom member and extending in the axial direction, and a lid configured to cover an open end provided at one axial end of the side wall member.

[0027] The electrode assembly can be in the form of a wound core wound around a predetermined axis.

[0028] An electrode joint can be provided at one end of the two axial ends of the electrode assembly opposite to the open end, and the current collector plate can be connected to the electrode joint.

[0029] The current collector plate can include an electrode joint connection portion that is in electrical contact with the electrode joint.

[0030] The current collector plate includes a can connection portion that is in electrical contact with the can.

[0031] The can connection portion and the electrode joint connection portion can be electrically connected.

[0032] The can connection portion can be disposed more radially outward than the electrode joint connection portion.

[0033] The first welding portion is formed at a plurality of positions and spaced apart from each other in the circumferential direction. In the first welding portion, the edge of the open end of the side wall member, the edge of the lid, and the can connection portion are welded together.

[0034] The first welding portion can be formed intermittently during the process of forming the second welding portion. In the second welding portion, at least the edge of the open end of the side wall member and the edge of the lid are welded by seam welding.

[0035] The first welding portion can be provided at four or more places.

[0036] The first welding portion can be provided at 24 or more places.

[0037] The second welding portion can be provided to be connected to the first welding portion in the circumferential direction.

[0038] The second welding portion can be provided between adjacent first welding portions in the circumferential direction.

[0039] The first welding portion and the second welding portion can be formed by laser welding.

[0040] The first welding portion and the second welding portion can be formed by common scan welding (i.e., one-time scan welding).

[0041] The circumferential length of the first welding portion can be about 0.1 mm to 6 mm.

[0042] Therefore, the generation of welding heat for forming the first welding portion can be suppressed.

[0043] The output of the laser beam in the section where the first welding portion is formed can be greater than the output of the laser beam in the section where the second welding portion is formed.

[0044] The energy density of the laser irradiation area in the section where the first welding portion is formed can be higher than the energy density of the laser irradiation area in the section where the second welding portion is formed.

[0045] The laser scanning speed in the section forming the first welded portion and the laser scanning speed in the section forming the second welded portion may be constant.

[0046] The laser scanning speed in the section forming the second welded portion may be less than the laser scanning speed in the section forming the first welded portion.

[0047] The scanning speed related to the laser output in the section forming the first welded portion may be less than the scanning speed related to the laser output in the section forming the second welded portion.

[0048] The scanning speed related to the energy density in the laser irradiation area for forming the first welded portion may be less than the scanning speed related to the energy density in the laser irradiation area for forming the second welded portion.

[0049] The depth formed by the first welded portion in the axial direction may be greater than the depth formed by the second welded portion.

[0050] When observed in the circumferential direction, the cross-sectional area of the first welded portion may be greater than the cross-sectional area of the second welded portion.

[0051] In addition, third welded portions may be formed to be spaced apart from each other in the circumferential direction, in which the edges of the open ends of the side wall members and the edges of the lid are welded.

[0052] The third welded portion may be a preliminary welded portion.

[0053] The first welded portion and the second welded portion may be main welded portions. If the third welded portion is formed by preliminary welding before the main welding for forming the first welded portion and the second welded portion, the gap caused by the component tolerances of the can and the lid can be fixed, and resistance can be provided against the thermal deformation occurring during the welding process.

[0054] The main welded portion may be formed on the preliminary welded portion. Thus, the preliminary welded portion may overlap with the main welded portion.

[0055] The welding depth and / or welding area of the third welded portion may be less than the welding depth and / or welding area of the second welded portion.

[0056] The welding depth and / or welding area of the second welded portion may be less than the welding depth and / or welding area of the first welded portion.

[0057] The section in which the third welded portion is formed in the circumferential direction may be configured not to overlap with the section in which the first welded portion is formed. Thus, in the section where triple welding is performed, the laser beam does not meet the boundary surface of the third welded portion (i.e., the preliminary welded portion), enabling the molten pool to expand stably.

[0058] The section formed with the third welding portion in the circumferential direction may be configured to overlap with the section formed with the second welding portion. Since this has a normal relationship between the preliminary welding and the main welding, the sealing reliability of the second welding portion can be ensured.

[0059] The can connection portion may include a first portion in contact with the side wall member and a second portion in contact with the lid.

[0060] The first portion may include an outer abutting surface facing the inner surface of the side wall member in the radial direction. At least a part of the first section, which is an axial section of the outer abutting surface, may be in contact with the inner surface of the side wall member.

[0061] The second portion may include a lid abutting surface facing and contacting the inner surface of the lid in the axial direction.

[0062] The lid may include an outer bonding surface facing the inner surface of the side wall member in the radial direction.

[0063] The outer bonding surface of the lid may face and contact the inner surface of the side wall member in the radial direction.

[0064] The lid may include a current collector plate abutting surface defined by the axial inner surface of the lid and axially facing and contacting the lid abutting surface of the can connection portion of the current collector plate.

[0065] The outer bonding surface of the lid may be axially and radially outwardly disposed from the current collector plate abutting surface.

[0066] The lid may include an inclined surface disposed inwardly in the radial direction from the current collector plate abutting surface on the axial inner surface of the lid and axially extending inwardly when it is closer to the inside in the radial direction.

[0067] The inclined surface may contact at least one corner of the axial outer end and the radial inner end of the can connection portion of the current collector plate.

[0068] Therefore, the center of the current collector plate and the center of the lid may be aligned.

[0069] Therefore, the axial outer end of the can connection portion may receive a force acting outwardly in the radial direction.

[0070] The outer diameter of the first section of the outer abutting surface is larger than the inner diameter of the inner surface of the side wall member with which it is in contact. Therefore, the first section of the outer abutting surface can be forced against the side wall member.

[0071] The current collector plate may be softer than the side wall member of the can.

[0072] At one axial end, the inner diameter of the side wall member may expand.

[0073] The side wall member may include an inner diameter expansion portion where the inner diameter of the side wall member increases, a first inner surface provided inward in the axial direction from the inner diameter expansion portion, and a second inner surface provided outward in the axial direction from the inner diameter expansion portion, wherein the inner diameter of the second inner surface is larger than the inner diameter of the first inner surface.

[0074] The outer abutting surface of the can connection portion may face and contact the second inner surface.

[0075] The outer coupling surface of the lid may face or contact the second inner surface.

[0076] The outer diameter of the first section of the outer abutting surface may be larger than the inner diameter of the first inner surface and may correspond to or be smaller than the inner diameter of the second inner surface.

[0077] The can connection portion may be configured to axially extend outward from a bent portion obtained by bending a current collector plate extending outward in the radial direction axially outward.

[0078] If the outer diameter of the outer abutting surface is set to be slightly larger than the inner diameter of the second inner surface, the outer abutting surface may be pressed against the second inner surface during the process of inserting the current collector plate, so that the outer abutting surface and the second inner surface may be in tight radial contact.

[0079] As a result, in the state where the current collector plate is inserted, the outer diameter of the outer abutting surface may correspond to the inner diameter of the second inner surface.

[0080] The axial ends of the outer coupling surface of the lid and the inner surface of the side wall member facing each other in the radial direction may be axially outwardly exposed.

[0081] The first welding portion and the second welding portion may be formed by laser beams irradiated from the axial outer side of the battery cell to the axial ends of the outer coupling surface of the lid and the inner surface of the side wall member.

[0082] In this case, since the outer abutting surface of the current collector plate provided axially inward from the lid may face and contact the inner surface of the side wall member, the laser beam can be prevented from directly irradiating the internal space of the can.

[0083] The inner diameter expansion portion can prevent the laser that may irradiate into the gap between the side wall member and the current collector plate from penetrating to the inside.

[0084] The current collector plate may have a higher thermal conductivity than the side wall member. Therefore, the heat generated when the first welding portion and the second welding portion are formed can be dissipated to the electrode assembly through the current collector plate, thereby preventing the welding heat from damaging the separator of the electrode assembly.

[0085] A protruding portion may be provided at one axial end of the side wall member to protrude further outward in the axial direction than the lid.

[0086] During the process of forming the first welding portion and the second welding portion, the protruding portion can be melted to flow into the welding portion between the inner surface of the sidewall member and the outer bonding surface of the lid. Therefore, even if there are differences in the welding process, the welding portion can be formed on the entire outer bonding surface of the lid in the axial direction.

[0087] The protruding portion can be melted during the process of forming the first welding portion and the second welding portion in the main welding. Therefore, the height of the battery cell can be defined by the surface of the lid, and as a result, the height dimension of the battery cell can be controlled at a constant level.

[0088] The present disclosure provides a method of manufacturing the above-described battery cell.

[0089] The battery cell includes: a can including a bottom member, a sidewall member connected to the bottom member and extending in the axial direction, and a lid covering an open end provided at one axial end of the sidewall member; and an electrode assembly accommodated in the can.

[0090] The method of manufacturing the battery cell may include a preparation step of bonding a current collector plate to an electrode terminal provided at one end of the two axial ends of the electrode assembly opposite to the open end.

[0091] The manufacturing method includes a first step of inserting the current collector plate into the can and bringing an outer abutting surface of a can connection portion provided at a radially outer edge of the current collector plate into contact with an inner surface of the sidewall member.

[0092] The manufacturing method includes a second step of covering the open end of the sidewall member with the lid, bringing an outer bonding surface provided at an edge of the lid to face the inner surface of the sidewall member in the radial direction, and bringing a current collector plate abutting surface into contact with a lid abutting surface of the current collector plate in the axial direction.

[0093] The manufacturing method includes a third step of forming a welding portion at an abutting portion between the inner surface of the sidewall member and the outer bonding surface of the lid.

[0094] In this case, a protruding portion of the sidewall member that protrudes further outward than the lid in the axial direction can be melted to flow into the welding portion between the inner surface of the sidewall member and the outer bonding surface of the lid.

[0095] In the third step, while continuously irradiating a laser beam in the circumferential direction, the laser beam is irradiated onto the abutting portion between the inner surface of the sidewall member and the outer bonding surface of the lid from the axial outside in the axial direction, and welding is performed such that the first welding portion and the second welding portion alternate. In the first welding portion, the inner surface of the sidewall member, the outer bonding surface of the lid, and the can connection portion of the current collector plate are welded together, and in the second welding portion, at least the inner surface of the sidewall member and the outer bonding surface of the lid are welded together.

[0096] In this case, the first welding portion and the second welding portion may be alternately formed such that the circumferential length of the second welding portion is formed to be longer than the circumferential length of the first welding portion.

[0097] A preliminary welding step may be further performed between the second step and the third step.

[0098] In the preliminary welding step, a plurality of third welding portions may be formed to be spaced apart from each other in the circumferential direction, and in the third welding portion, the edge of the open end of the side wall member and the edge of the lid are welded.

[0099] In the third step, the intensity of the laser beam irradiated on the section for welding the first welding portion or the energy density of its laser irradiation area may be stronger or higher than the intensity of the laser beam irradiated on the section for welding the second welding portion or the energy density of its laser irradiation area.

[0100] In the third step, the moving speed of the irradiation area of the laser beam irradiated on the section for welding the first welding portion and the moving speed of the irradiation area of the laser beam irradiated on the section for welding the second welding portion may be constant.

[0101] In the third step, the scanning speed related to the output of the laser beam in the section for forming the first welding portion may be less than the scanning speed related to the output of the laser beam in the section for forming the second welding portion.

[0102] In the third step, the scanning speed related to the energy density of the laser irradiation area for forming the first welding portion may be less than the scanning speed related to the energy density of the laser irradiation area for forming the second welding portion.

[0103] Advantageous Effects

[0104] According to the present disclosure, compared with welding the entire circumferential section of the can, the current collector plate, and the lid together, it is possible to ensure the electrical connection of the current collector plate and the sealing of the can while suppressing the generation of welding heat.

[0105] On the other hand, according to the present disclosure, it is possible to sufficiently achieve the required internal resistance and reliably seal the can while suppressing the generation of welding heat.

[0106] On the other hand, according to the present disclosure, it is possible to ensure weldability, stability, and durability while welding the side wall member, the lid, and the current collector plate together.

[0107] On the other hand, according to the present disclosure, it is possible to significantly reduce the assembly work of the battery cell by welding the side wall member, the lid, and the current collector plate together.

[0108] On the other hand, according to the present disclosure, since no welding is required inside the can, the risk of foreign substances such as welding spatter infiltrating into the electrode assembly and causing defects can be eliminated.

[0109] On the other hand, according to the present disclosure, the maximum volume of the electrode assembly accommodated in the can can be ensured, thereby increasing the energy density of the battery cell.

[0110] In addition to the above effects, the specific effects of the present disclosure will be described in the following detailed description of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0111] Figure 1 is a perspective view of a cylindrical battery cell according to an embodiment.

[0112] Figure 2 is the Figure 1 exploded perspective view of the electrode assembly (not yet wound) accommodated in the can.

[0113] Figure 3 is the Figure 2 perspective view of the unwound electrode assembly in a laminated state.

[0114] Figure 4 is the Figure 3 perspective view of the electrode assembly assembled into a cylindrical wound core shape by winding the laminate in.

[0115] Figure 5 is a perspective view showing the state of the first current collector plate being coupled to the electrode tab of the first electrode of the electrode assembly.

[0116] Figure 6 is a perspective view showing the state of the second current collector plate being coupled to the electrode tab of the second electrode of the electrode assembly.

[0117] Figure 7 is a side cross-sectional view showing the process of storing the electrode assembly with the coupled current collector plates in the can.

[0118] Figure 8 is a side cross-sectional view showing the process of coupling the first current collector plate of the electrode assembly accommodated in the can to the first electrode terminal.

[0119] Figure 9 is a side cross-sectional view showing the process of covering the open end of the can accommodating the electrode assembly with a lid.

[0120] Figure 10 is a side cross-sectional view showing the state of covering the open end of the can accommodating the electrode assembly with a lid.

[0121] Figure 11 is the Figure 9 enlarged view of the rectangular area in.

[0122] Figure 12 is Figure 10 an enlarged view of the rectangular area in

[0123] Figure 13 is one in which Figure 12 an enlarged view of the portion where the current collector plate, the lid, and the can abut each other in

[0124] Figure 14 is a plan view showing the state where the lid and the can are preliminarily welded.

[0125] Figure 15 is showing Figure 14 a cross-sectional view of the configuration in

[0126] Figure 16 is a plan view showing the state where the lid and the can are permanently welded.

[0127] Figure 17 is showing Figure 16 a cross-sectional view of the configuration in

[0128] Figure 18 is showing Figure 16 a cross-sectional view of the configuration in

[0129] Figure 19 is showing Figure 16 a cross-sectional view of the configuration in

[0130] Figure 20 is showing Figure 12 an enlarged view of a modified example of the can in

[0131] Figure 21 is a flowchart showing an example of a process for manufacturing a battery cell according to an embodiment.

[0132] Figure 22 and Figure 23 show a battery pack of a battery cell to which this embodiment is applied and a vehicle equipped with such a battery pack. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0133] The above objects, features, and advantages will be described in detail below with reference to the accompanying drawings, so that those skilled in the art to which the present disclosure pertains can easily implement the technical concept of the present disclosure. In describing the present disclosure, descriptions of related known technologies that may obscure the subject matter of the present disclosure will be omitted. Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to denote the same or similar elements.

[0134] Although terms such as "first", "second" are used to describe various elements, these elements are not limited by these terms. These terms are only used to distinguish one element from another, and unless otherwise specified, the first element may also be the second element.

[0135] Throughout the specification, unless otherwise specified, each element may include a single element or multiple elements.

[0136] Hereinafter, a configuration in which an element is "in the upper (or lower) part" or "at the top (or bottom)" of a target element may mean that the element can be arranged to contact the upper surface (or lower surface) of the target element, and another element may be interposed between the target element and the element arranged at the top (or bottom) of the target element.

[0137] In addition, the expressions "an element is 'connected', 'coupled' or 'contacted' to another element" should be understood that these elements can be directly connected, coupled or contacted with each other, and another element may be "interposed" between these elements, or these elements can be "connected", "coupled" or "contacted" with each other through other elements.

[0138] When used herein, unless otherwise clearly specified, singular expressions include plural expressions. In this document, the terms "configured to have" or "include" should not be construed as necessarily including all of the respective elements or all of the respective steps described in the specification, but should be construed as capable of excluding some elements or some steps, or capable of further including additional elements or steps.

[0139] Throughout the specification, unless otherwise specified, "A and / or B" may mean A, B, or A and B, and unless otherwise specified, "C to D" may mean "equal to or greater than C and equal to or less than D".

[0140] In the description of the embodiments, the axial direction represents the direction in which the winding axis of the electrode assembly wound in a core shape extends, the radial direction represents the direction approaching (centripetal direction) or away from (centrifugal direction) the winding axis, and the circumferential direction represents the direction around the winding axis.

[0141] Hereinafter, reference will be made to Figures 1 to 19 Embodiments of a battery cell applying the welding structure of the present disclosure will be described in detail.

[0142] The battery cell of the embodiment may be, for example, a cylindrical battery cell having a shape factor ratio (defined as the ratio of the diameter (φ) to the height (H) of the cylindrical battery cell) greater than about 0.4.

[0143] Here, the form factor represents values indicating the diameter and height of a cylindrical battery cell. The cylindrical battery cell can be, for example, a 46110 cell, a 48750 cell, a 48110 cell, a 48800 cell, a 46800 cell, a 4690 cell, or a 4695 cell. In the values representing the form factor, the first two digits represent the diameter of the cell, the last two digits represent the height of the cell, and the last digit 0 indicates that the cross-section of the cell is circular.

[0144] The battery cell can be a cylindrical battery cell having a diameter of about 46 mm, a height of about 110 mm, and a form factor ratio of 0.418.

[0145] According to another embodiment, the battery cell can 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.

[0146] According to another embodiment, the battery cell can be a cylindrical battery cell having a diameter of about 48 mm, a height of about 110 mm, and a form factor ratio of 0.418.

[0147] According to another embodiment, the battery cell can be a cylindrical battery cell having a diameter of about 48 mm, a height of about 80 mm, and a form factor ratio of 0.600.

[0148] According to another embodiment, the battery cell can be a cylindrical battery cell having a diameter of about 46 mm, a height of about 80 mm, and a form factor ratio of 0.575.

[0149] The present disclosure can also be applied to battery cells having a form factor ratio of about 0.4 or less, such as 18650 cells, 21700 cells, etc. In the case of an 18650 cell, the diameter is about 18 mm, the height is about 65 mm, and the form factor ratio is 0.277. In the case of a 21700 cell, the diameter is about 21 mm, the height is about 70 mm, and the form factor ratio is 0.300.

[0150] The battery cell of the embodiment can include an electrode assembly 20, current collectors 31 and 32 electrically connected to the electrode assembly 20, and a can 10 that houses the electrode assembly 20 and the current collectors 31 and 32.

[0151] The can 10 can include a bottom member 12, a side wall member 11 connected to the bottom member 12 and extending in the axial direction, and a lid 16 that covers an open end provided at one axial end of the side wall member 11. Here, the axial direction can represent a direction parallel to the winding axis of the electrode assembly 20 of the present disclosure.

[0152] The bottom member 12 may have a disk shape with a hole formed in the center. The side wall member 11 may have the shape of a circular tube. That is, the side wall member 11 may have a hollow cylindrical shape.

[0153] The bottom member 12 and the side wall member 11 may be formed integrally. The bottom member 12 and the side wall member 11 can be manufactured by forming a nickel-plated metal sheet on a steel surface via a deep drawing process and trimming the front end of the side wall member 11 with a punch while holding the side wall member 11 with a pressing plate. In addition, the material of the can 10 is not limited to this.

[0154] The first electrode terminal 13 may be fitted into the hole. The first electrode terminal 13 may be fixed to the bottom member 12 by riveting. A washer 14 may be interposed between the first electrode terminal 13 and the can 10. The washer 14 may be interposed between the first electrode terminal 13 and the bottom member 12 to seal the portion between the inner and outer sides of the can 10, thereby preventing electrolyte leakage and electrically insulating the first electrode terminal 13 and the bottom member 12 from each other.

[0155] However, the connection method between the first electrode terminal 13 and the bottom member 12 is not limited to this. For example, various other fixing methods such as a bolt-nut joining method, a glass sealing method, or a thermal bonding method of chromium coating and PP-MAH may also be applied as long as the portion between the first electrode terminal 13 and the bottom member 12 can be sealed and the first electrode terminal 13 and the bottom member 12 can be electrically insulated from each other.

[0156] The first electrode terminal 13 may have a first polarity, and the can 10 may have a second polarity opposite to the first polarity. That is, the bottom member 12 of the can 10, the side wall member 11 connected to the bottom member 12, and the lid 16 (to be described later) connected to the side wall member 11 may all have the second polarity.

[0157] Therefore, the battery cell may have the first electrode terminal 13 and the second electrode terminal 15 both disposed at the axial end (i.e., the closed end) where the bottom member 12 is provided. Thus, the battery cell may have both a bus bar connected to the first electrode terminal 13 and a bus bar connected to the second electrode terminal 15 located at the top of the battery cell.

[0158] In one example, the first electrode terminal 13 may be a positive terminal, and the second electrode terminal 15 may be a negative terminal. In addition, the opposite case is also possible.

[0159] The electrode assembly 20 is accommodated inside the can 10. The electrode assembly 20 can be manufactured in the form of a wound core by preparing the first electrode 21, the second electrode 22, and the separator 28 having a predetermined width and extending in the longitudinal direction as Figure 2 shown, and byFigure 3 A laminate is formed by successively laminating a first electrode 21, a separator 28, a second electrode 22, and a separator 28, and then the laminate is wound around a winding axis as Figure 4 shown.

[0160] The first electrode 21 may be a positive electrode, and the second electrode 22 may be a negative electrode. Additionally, the opposite case is also possible.

[0161] The first electrode 21 and the second electrode 22 may be manufactured in the form of sheets. The electrode sheets are manufactured such that an active material layer 24 is coated on the surface of a metal foil 23. The electrode sheet has a coated area 25 coated with the active material layer 24 and an uncoated area 26 not coated with the active material layer 24. The positive electrode sheet may have an uncoated area 26 on one side in the width direction. The negative electrode sheet may have an uncoated area 26 on the other side in the width direction.

[0162] The uncoated area 26 may be exposed or protrude from the laminate in the width direction. The width direction of the laminate may represent a direction parallel to the winding axis of the electrode assembly 20. The uncoated area 26 itself may be used as an electrode tab 27.

[0163] Notches may be formed at a predetermined interval in the uncoated area 26 to form a flag-shaped notch tab 27.

[0164] This embodiment shows an example in which the notch tab 27 is configured in an equilateral trapezoid shape. However, the notch tab 27 may have various shapes such as semicircular, semi-ovoid, triangular, rectangular, and parallelogram.

[0165] Additionally, this embodiment shows an example in which the notch tab 27 provided in the longitudinal direction has the same width. However, the width of the notch tab may gradually or stepwise increase from the core to the outside.

[0166] Additionally, this embodiment shows an example in which the height of the notch tab 27 gradually increases from the core to the outside. However, the height of the notch tab may be made constant or gradually decrease.

[0167] Additionally, this embodiment shows an example in which the notch tab 27 is excluded from a predetermined section adjacent to the core and a predetermined section adjacent to the outside of the uncoated area 26. However, it is obvious that the notch tab may not be excluded from the predetermined section adjacent to the core of the uncoated area, and the notch tab may not be excluded from the predetermined section adjacent to the outside of the uncoated area.

[0168] As Figure 4 shown, in the core-type electrode assembly 20, the notch tab 27 may be radially bent and flattened. The notch tab 27 may be bent radially inward or outward. This embodiment shows an example in which the notch tab 27 is bent radially inward.

[0169] The notch joints 27 can be bent one by one during the process of forming the core-type electrode assembly 20 by winding the laminate. On the other hand, all the notch joints 27 can be bent at one time after forming the core-type electrode assembly by winding the laminate.

[0170] The notch joints 27 of the first electrode 21 and the notch joints 27 of the second electrode 22 that are radially bent and laminated as described above can provide planes substantially perpendicular to the axial direction at both axial ends of the electrode assembly 20.

[0171] As Figure 5 and Figure 6 shown, the first current collector plate 31 and the second current collector plate 32 can be coupled to the substantially flat surfaces provided by exposing through the two axial ends of the electrode assembly 20 by bending the notch joints 27.

[0172] This embodiment shows an example where the first current collector plate 31 is a positive current collector plate and the second current collector plate 32 is a negative current collector plate. The first current collector plate 31 can be made of aluminum, and the second current collector plate 32 can be made of copper.

[0173] The current collector plates 31 and 32 can be manufactured by stamping, trimming, perforating, and bending a metal sheet.

[0174] Referring Figure 5 , the first current collector plate 31 can include a terminal connection portion 312 extending radially from the center, an edge portion 313 connected to the outer end of the terminal connection portion 312 and extending in the circumferential direction, and an electrode connection portion 314 extending from the edge portion 313 toward the core portion. The electrode connection portion 314 can be spaced apart from the terminal connection portion 312 in the radial direction. The center of the terminal connection portion 312 covers at least a part of the core hollow portion of the electrode assembly 20. The central region of the terminal connection portion 312 can be coupled to the first electrode terminal 13.

[0175] Before the electrode assembly 20 is stored in the can 10, the electrode connection portion 314 can be coupled to the notch joint 27 of the first electrode 21 of the electrode assembly 20 by laser welding or the like. The welding line of the laser can extend radially.

[0176] Referring Figure 6 , the second current collector plate 32 can have a hole 322 corresponding to the core hollow portion (winding center hole) of the electrode assembly 20. The second current collector plate 32 can include an inner ring portion 321 configured to surround the core hollow portion, an electrode joint connection portion 323 extending radially from the inner ring portion 321, and a can connection portion 324 disposed more outward than the electrode joint connection portion 323 and connected to the inner ring portion 321. The can connection portion 324 can be configured to surround the edge of the second current collector plate 32.

[0177] Before inserting the electrode assembly 20 into the can 10, the electrode joint connection portion 323 can be joined to the notch joint 27 of the second electrode 22 of the electrode assembly 20 by laser welding or the like. The welding line of the laser can extend radially.

[0178] As shown in this embodiment, the first current collector plate 31 and the second current collector plate 32 can be joined to the electrode assembly 20 before inserting the electrode assembly 20 into the can 10.

[0179] In addition, the electrode assembly 20 having only the first current collector plate 31 joined thereto can be stored inside the can 10, and then the second current collector plate 32 can be inserted into the can 10 so as to join the second current collector plate 32 to the electrode assembly 20.

[0180] As Figure 7 and Figure 8 shown, the electrode assembly 20 can be stored inside the can 10 in a state where the first current collector plate 31 is aligned to face the bottom member 12 of the can 10. In this case, the insulator 19 can be interposed between the first current collector plate 31 and the bottom member 12 of the can 10 so that the first current collector plate 31 and the bottom member 12 are electrically insulated from each other. In a state where the electrode assembly 20 is inserted, the edge of the second current collector plate 32 contacts the can 10.

[0181] In addition, the terminal connection portion 312 of the first current collector plate 31 can be joined to the first electrode terminal 13 fixed to the can 10 by resistance welding, ultrasonic welding, laser welding, or the like. The welding device A for welding the first current collector plate 31 and the first electrode terminal 13 can approach the center of the terminal connection portion 312 of the first current collector plate 31 from the open end of the can 10 through the core hollow portion of the electrode assembly 20, thereby performing welding. Alternatively, a laser beam can pass through the core hollow portion of the electrode assembly 20 and irradiate the inner surface of the center of the terminal connection portion 312 of the first current collector plate 31, thereby welding the terminal connection portion 312 and the first electrode terminal 13. In addition, the first current collector plate 31 and the first electrode terminal 13 can also be joined by brazing or soldering. That is, any method can be applied as long as the first current collector plate 31 and the first electrode terminal 13 can be electrically connected and fixed to each other.

[0182] In a state where the electrode assembly 20 is accommodated inside the can 10, the electrode joint 27 of the second electrode 22 and the second current collector plate 32 can be arranged to face the open end of the side wall member 11.

[0183] After the first current collector plate 31 and the first electrode terminal 13 are joined, the electrolyte can be injected into the can 10.

[0184] As Figure 9 shown, after injecting the electrolyte, the open end of the side wall member 11 can be covered and sealed by the lid 16.

[0185] As Figure 10 shown, the edge of the lid 16 can abut against the edge of the can 10 and the second current collector plate 32.

[0186] Referring Figure 11 and Figure 12 , the side wall member 11 of the can 10 can have an inner diameter expansion portion 113 at the open end. The inner diameter expansion portion 113 can have an inclined surface provided on the inner surface of the side wall member 11 such that the inner diameter of the side wall member 11 increases as it gets closer to the outside in the axial direction. That is to say, the inner diameter expansion portion 113 can include an inclined surface which is provided on the inner surface of the side wall member 11 and extends radially outward as it gets closer to the outside in the axial direction.

[0187] Therefore, the inner surface of the side wall member 11 can include a first inner surface 111 which is axially more inwardly disposed than the inner diameter expansion portion 113, and a second inner surface 115 which is axially more outwardly disposed than the inner diameter expansion portion 113.

[0188] The outer diameter of the side wall member 11 can be uniform in the axial direction, while the inner diameter of the second inner surface 115 can be larger than the inner diameter of the first inner surface 111. Therefore, the radial thickness of the side wall member 11 in the section of the second inner surface 115 can be smaller than the radial thickness in the section of the first inner surface 111.

[0189] The can connection portion 324 provided at the edge of the second current collector plate 32 and in electrical contact with the can 10 can include a first portion which at least partially faces or contacts the inner surfaces 111, 113 or 115 of the side wall member 11. An outer abutting surface 325 can be provided on the first portion to face or contact the inner surfaces 111, 113 or 115 of the side wall member 11 in the radial direction.

[0190] The can connection portion 324 can include a second portion in contact with the lid 16. A lid abutting surface 326 can be provided on the second portion to face and contact the axial inner surface of the lid 16.

[0191] The second current collector plate 32 can include a bending portion 327. The bending portion 327 is configured such that the second current collector plate 32 extending outward in the radial direction bends outward in the axial direction. The can connection portion 324 of the second current collector plate 32 can be connected to the electrode joint connection portion 323 through the above-mentioned inner ring portion 321 and the bending portion 327.

[0192] The can connection portion 324 can be connected to the axially outer side of the bending portion 327 and can be configured to extend axially outward from the bending portion 327. Therefore, the area and axial length of the outer abutting surface 325 of the second current collector plate 32 can be further ensured.

[0193] The material of the second current collector plate 32 may be softer than the material of the side wall member 11.

[0194] The thermal conductivity of the second current collector plate 32 may be higher than the thermal conductivity of the side wall member 11.

[0195] For example, the material of the second current collector plate 32 may include copper. The material of the side wall member 11 may include iron. However, the materials of the second current collector plate 32 and the side wall member 11 of the present disclosure are not limited thereto.

[0196] The outer diameter of the outer abutting surface 325 of the can connection portion 324 may be set to be larger than the inner diameter of the first inner surface 111. The outer diameter of the outer abutting surface 325 may correspond to or be smaller than the inner diameter of the second inner surface 115.

[0197] Thus, when the second current collector plate 32 is inserted, the bending portion 327 elastically deforms, and the outer abutting surface 325 is forced against the first inner surface 111, so that the outer abutting surface 325 and the first inner surface 111 can be in close contact in the radial direction. As a result, the outer diameter of the first section a of the outer abutting surface 325 that is pressed against the first inner surface 111 in the axial direction corresponds to the inner diameter of the first inner surface 111.

[0198] As described above, the multi-stage inner surface structure of the side wall member 11 and the structure of the can connection portion 324 of the current collector plate 32 can ensure that at least the axial portion of the outer abutting surface 325 is in close contact with the inner surface of the side wall member 11.

[0199] The bending portion 327 may provide a curved surface whose outer diameter gradually decreases from the axial inner end of the can connection portion 324 toward the axial inner side. In addition, the minimum outer diameter d of the curved surface measured at the lower end of the second current collector plate 32 may be smaller than the inner diameter of the first inner surface 111. During the process of inserting the second current collector plate 32 into the inner space of the side wall member 11, this shape can guide the can connection portion 324 to be forced against the first inner surface 111. Therefore, the process of forcibly pressing the second current collector plate 32 can be more easily performed.

[0200] As a result, according to the present disclosure, as long as the dimensional relationship is maintained such that the minimum outer diameter d of the bending portion 327 is smaller than the inner diameter of the first inner surface 111 of the side wall member 11, and the outer diameter of the outer abutting surface 325 of the second current collector plate 32 is larger than the inner diameter of the first inner surface 111, even if there are dimensional tolerances of the components, the following effects can be obtained: wherein the first section a of the outer abutting surface 325 is in close contact with the first inner surface 111 of the side wall member 11 in the forced assembly portion P. In addition, such dimensional management can be easily achieved.

[0201] Therefore, in the present disclosure, even during the following welding process, a part of the laser beam L such as Figure 13Irradiated as shown into the interior of the can, it will also be blocked by the second inner surface 115, the outer abutting surface 325, and the inner diameter expansion part 113, so that the laser beam L may not reach the components accommodated inside the can 10.

[0202] The lid 16 may have, in order from the radial center to the outside, a lid body 160, a thickness reduction part 161, and a coupling part 17. That is, the thickness reduction part 161 may be disposed adjacent to the radial outside of the lid body 160, and the coupling part 17 may be disposed on the radial outside of the thickness reduction part 161.

[0203] Therefore, a first thickness t1 of the coupling part 17 measured in the axial direction may be configured to be less than a second thickness t2 of the lid body 160 measured in the axial direction.

[0204] An outer coupling surface 171 may be provided on the coupling part 17 of the lid 16 to face the second inner surface 115 of the side wall member 11 in the radial direction, so as to be close to or in contact with the second inner surface 115. In addition, a current collector plate abutting surface 173 may be provided on the axial inner surface of the coupling part 17 of the lid 16 to face and contact the lid abutting surface 326 of the can connection part 324 of the second current collector plate 32 in the axial direction.

[0205] A welding part described below may be formed between the outer coupling surface 171 of the lid 16 and the second inner surface 115 of the side wall member 11. Accordingly, even if the lid 16 and the side wall member 11 are welded to a depth of the first thickness t1, the abutting part between the lid 16 and the side wall member 11 can be completely coupled and connected. Then, even if an expansion phenomenon occurs in the lid 16 due to an increase in the internal pressure of the can 10, no stress concentration will occur at the coupling part of the can 10 and the lid 16, and the thick lid body 160 can strongly resist expansion.

[0206] The thickness reduction part 161 is a thickness changing part provided in the lid 16.

[0207] By appropriately selecting the position of the thickness reduction part 161 such that at least a part of the thickness reduction part 161 contacts the second current collector plate 32, the thickness reduction part 161 of the lid 16 can contact the second current collector plate 32 during the process of inserting the lid 16, facilitating the alignment of the lid 16.

[0208] In this embodiment, the thickness reduction part 161 is implemented in the form of an inclined surface that axially extends outward as it approaches the radial outside of the lid 16 to enhance the alignment effect.

[0209] During the process of inserting the lid 16 into the side wall member 11, the thickness reducing portion 161 in the form of an inclined surface may contact the radially inner edge of the lid contact surface 326. Accordingly, the axially outer end of the tank connection portion 324 of the second current collector plate 32 provided with the lid contact surface 326 may be radially outwardly pressed by the thickness reducing portion 161, and thus may be set to be closer to or in closer contact with the second inner surface 115 of the side wall member 11.

[0210] That is to say, during the process of inserting the lid 16 through the open end of the side wall member 11, the thickness reducing portion 161 in the form of an inclined surface may contact the tank connection portion 324 of the second current collector plate 32, thereby guiding the alignment of the lid 16 relative to the center of the second current collector plate 32, and radially outwardly pressing the axially outer end of the tank connection portion 324 of the second current collector plate 32 so that the axially outer end of the tank connection portion 324 of the second current collector plate 32 is in close contact with the second inner surface 115 of the side wall member 11.

[0211] For the lid 16 according to this embodiment, the radial position of the thickness reducing portion 161 may be set as close as possible to the welding portion, so that the area of the lid body 160 resisting expansion can be ensured to the maximum extent. In addition, this selection of the position of the thickness reducing portion 161 can also provide a guiding function for aligning the lid 16 while in contact with the second current collector plate 32.

[0212] In a state where the lid 16 is inserted through the open end of the side wall member 11, the outer engagement surface 171 of the lid 16 and the outer contact surface 325 of the second current collector plate 32 may tightly face or contact the second inner surface 115 of the side wall member 11 in the radial direction. That is to say, the outer engagement surface 171 of the lid 16 may face or contact the second inner surface 115 in the radial direction, and the outer contact surface 325 of the tank connection portion 324 may face or contact the second inner surface 115 in the radial direction at a position axially more inward than the outer engagement surface 171.

[0213] In addition, the lid contact surface 326 provided at the axially outer end of the tank connection portion 324 of the second current collector plate 32 may contact the current collector plate contact surface 173 provided on the inner surface of the joint portion 17 of the lid 16 in the axial direction.

[0214] According to this assembly structure, the insertion depth of the lid 16 can be accurately determined by the height H of the second current collector plate 32, and the height H may be affected by the axial extension length of the tank connection portion 324.

[0215] Meanwhile, due to dimensional differences caused by component manufacturing processes and the like, there may be some errors in the outer diameter of the outer joint surface 171 of the cover 16, the inner diameter of the second inner surface 115 of the side wall member 11, and / or the outer diameter of the outer abutting surface 325 of the second current collector plate 32. The occurrence of such errors may prevent the outer joint surface 171 of the cover 16 and the outer abutting surface 325 of the second current collector plate 32 from coming into close contact with the second inner surface 115 of the side wall member 11. However, according to the battery cell structure of the present disclosure described above, the structure of the forced assembly portion P and the inner diameter expansion portion 113 shown in Figure 3 can significantly reduce the risk that the laser beam L irradiated for welding penetrates into the can 10 and damages the electrode assembly 20.

[0216] According to one aspect of the present disclosure, as shown in the figure, the axial ends of the outer joint surface 171 of the cover 16 and the inner surface of the side wall member 11 that abut against each other in the radial direction may be exposed to the axial outside.

[0217] The cover 16 can be welded to the can 10 by a laser beam L irradiated from the axial outside of the battery cell onto the axial end of the abutting portion between the outer joint surface 171 of the cover 16 and the second inner surface 115 of the side wall member 11.

[0218] The second current collector plate 32 described above can be made of a material with a higher thermal conductivity than the side wall member 11. As described above, if the thermal conductivity of the side wall member 11 is relatively low, the risk of damaging the separator provided in the electrode assembly 20 due to heat conduction generated during welding can be reduced. The second current collector plate 32 can be in contact with the side wall member 11. Therefore, the welding heat generated by the laser beam on the side wall member 11 can be conducted to the electrode assembly 20 through the second current collector plate 32, and the conducted welding heat can be transferred to the separator of the electrode assembly 20 facing the side wall member 11, thereby damaging the separator. However, as described above, if the thermal conductivity of the side wall member 11 is configured to be lower than that of the second current collector plate 32, the risk of damaging the separator due to heat conduction through the side wall member 11 can be reduced.

[0219] The process of combining and electrically connecting the second current collector plate 32 to the side wall member 11 of the can 10 and the process of sealing the can 10 by bonding the edge of the cover 16 to the side wall member 11 of the can 10 can be performed together by seam welding.

[0220] By seam welding, the edge of the cover 16 can be bonded to the side wall member 11 of the can 10 to be sealed, and at the same time, the second current collector plate 32 can be bonded to the side wall member 11 of the can 10.

[0221] As Figure 14As shown, this seam welding can be performed by irradiating a laser beam L onto the abutting portion extending in the circumferential direction of the outer joint surface 171 of the lid 16 and the second inner surface 115 of the side wall member 11 (i.e., by scanning and irradiating the laser beam in the circumferential direction onto the entire abutting portion).

[0222] As the scanning irradiation progresses, the laser irradiation region B moves along the abutting portion (see C in Figure 14 ), and thus, the molten pool is continuously generated, expanded, and solidified in the circumferential direction at the abutting portion.

[0223] If the consistency of the generation, expansion, and solidification of the molten pool is ensured during one seam welding process, the quality of the welded portion between the edge of the lid 16 and the end of the side wall member 11 of the can 10 can be improved, thereby fully ensuring the required sealing performance.

[0224] According to this embodiment, preliminary welding can be performed before seam welding, thereby increasing the matching of the can 10 and the lid 16 and increasing the resistance to deformation of the can 10 and the lid 16 that may occur due to the welding heat during the main welding. In addition, the seam welding can be performed as the main welding after the above-mentioned preliminary welding.

[0225] This embodiment shows an example of performing the main welding after the preliminary welding. However, it is obvious that the seam welding can also be performed without performing the preliminary welding.

[0226] Referring to Figure 14 and Figure 15 , the preliminary welding can be performed at a plurality of positions spaced apart from each other in the circumferential direction along the abutting portion of the can 10 and the lid 16. The preliminary welding can be performed, for example, by irradiating a laser beam having a lower output or a lower energy density than the main welding to slightly fix the can 10 and the lid 16.

[0227] For reference, the energy density is proportional to the value obtained by dividing the laser output by the area of the irradiation region. That is, the higher the laser output, the higher the energy density, and the wider the irradiation region, the lower the energy density.

[0228] The preliminary welding position and the welding degree can be determined to minimize the suppression of the expansion of the molten pool that may occur at the boundary of the preliminary welding region during the main welding while improving the matching and the resistance to deformation. Therefore, when the laser is scanned in the circumferential direction during the main welding process, the consistency and stability of the molten pool can be ensured.

[0229] This embodiment shows an example in which the preliminary welding portion W3 is formed to have the minimum welding area by performing the preliminary welding at the minimum required number of positions (i.e., four positions) so that no discontinuity of welding appears on the welding interface.

[0230] Seam welding can be continuously performed as the main welding along the circumferential direction at the abutting portion, so that the first welding portion W1 in which the can 10, the second current collector plate 32, and the lid 16 are welded together is intermittently formed, and the second welding portion W2 in which at least the can 10 and the lid 16 are welded together is formed in the remaining seam welding section.

[0231] This seam welding can be performed with a laser output, irradiation area, energy density, and scanning speed that can substantially form the second welding portion W2 for sealing and fixing the can 10 and the lid 16 while minimizing the generation of welding heat. At the same time, the seam welding can be performed by intermittently changing at least one of the laser output, irradiation area, energy density, and scanning speed during the laser scanning process. By intermittently changing the conditions of the laser scanning as described above, the first welding portion W1, which is a triple welding portion in which the can 10, the lid 16, and the second current collector plate 32 are welded together, can be formed.

[0232] As the number of the first welding portions W1 increases and as the formation section of the first welding portions W1 becomes longer, the internal resistance can be reduced.

[0233] However, in order to triple-weld the can 10, the lid 16, and the second current collector plate 32 together, the welding depth must be greater than that of the second welding portion W2, or the welding cross-sectional area must be wider when observed in the circumferential direction. However, this may result in a large amount of welding heat. Therefore, preferably, the first welding portion W1 is formed to a minimum value that reduces the internal resistance to a necessary level. Refer to Figure 16 , this embodiment shows the following example: wherein, four first welding portions W1 are provided at equal intervals, and wherein each first welding portion W1 is formed in a section less than about 15 degrees in the circumferential direction.

[0234] In the section where the first welding portion W1 is formed, it is necessary to satisfy at least one of the conditions that the laser output or the energy density increases, the irradiation area decreases, and the laser scanning speed decreases compared to the section where the second welding portion W2 is formed.

[0235] At the same time, since the process of forming the first welding portion W1 is intermittently performed during the seam welding process of forming the second welding portion W2, it is desirable to continuously maintain the stability and consistency of the molten pool held in the second welding portion W2.

[0236] In view of this, this embodiment proposes a method: during the laser scanning welding process, when forming the first welding portion W1 midway through the formation of the second welding portion W2, the energy density is increased by increasing the laser output while maintaining the irradiation area and the scanning speed. According to this embodiment, when forming the second welding portion W2 midway through the formation of the first welding portion W1, the irradiation area and the scanning speed can be maintained, and the laser output can be reduced again.

[0237] In addition, in the output increasing section where the second welding portion W2 switches to the first welding portion W1 and in the output decreasing section where the first welding portion W1 switches to the second welding portion W2, it is desirable to control the output of the laser to increase or decrease continuously rather than suddenly increase or decrease in a stepwise manner.

[0238] In addition, the output increasing rate in the output increasing section can be configured to be greater than the output decreasing rate in the output decreasing section.

[0239] When the laser irradiated at the first output (lower output) in the section for forming the second welding portion W2 increases to the second output (higher output) for forming the first welding portion W1 that is higher than the first output, the output is increased very quickly at the first increasing rate / decreasing rate, so as to quickly increase the generation of welding heat. Then, the generated welding heat can be concentrated on melting the portion to be welded before being transferred to another part, so that the triple welding of the can 10, the lid 16, and the second current collector plate 32 can be reliably performed, and the side effects of the welding heat transferred to the electrode assembly can be reduced.

[0240] When the laser irradiated at the second output in the section for forming the first welding portion W1 decreases to the first output for forming the first welding portion W1, the output is decreased somewhat slowly at the second increasing rate / decreasing rate that is lower than the first increasing rate / decreasing rate, so that the molten pool can expand stably.

[0241] Referring to Figures 16 to 19 , preferably, the first welding portion W1 forming section is arranged not to overlap with the preliminary welding portion (i.e., the third welding portion W3 forming position) in the circumferential direction. That is to say, the first welding portion W1 forming section and the third welding portion W3 forming section can not overlap with each other. In other words, the third welding portion W3 forming section can be included in the second welding portion W2 forming section.

[0242] However, the third welding portion W3 can be arranged in the first welding portion W1 forming section as long as the degree of interference with the expansion of the molten pool caused by the third welding portion W3 is not large.

[0243] Referring to Figure 20 , the side wall member 11 of the can 10 can extend longer than the side wall member 11 in the previous embodiment. Therefore, asFigure 20 As shown, in a state where the second current collector plate 32 and the lid 16 are inserted into the can 20, a protruding portion 117 that further axially protrudes outward than the lid 16 can be provided at an end of the side wall member 11. The thickness of the side wall member 11 can be smaller than the thickness of the lid 16.

[0244] In this case, the protruding portion 117 can delay the melting time of the side wall member 11 that is thinner than the lid 16, thereby reducing the difference in melting time between the side wall member 11 and the lid 16. In the process of forming the welded portion, the protruding portion 117 can be melted to flow into the welded portion between the second inner surface 115 of the side wall member 11 and the outer bonding surface 171 of the lid 16 (see Figure 13 ). Therefore, even if there is a deviation in the welding process, the welded portion can be formed on the entire outer bonding surface 171 of the lid 16 in the axial direction.

[0245] As Figure 19 shown, in the section where the first welded portion W1 is formed, the protruding portion 117 can be completely melted to flow into the abutting portion of the second inner surface 115 of the side wall member 11, the outer bonding surface 171 of the lid 16, and the can connection portion 324 of the second current collector plate 32.

[0246] As Figure 17 shown, in the section where the second welded portion W2 is formed, the protruding portion 117 can be completely melted to flow into the abutting portion between the second inner surface 115 of the side wall member 11 and the outer bonding surface 171 of the lid 16. Therefore, the height of the battery cell can be defined by the outer surface of the lid 16. That is to say, according to the variant example, since the protruding portion 117 and the welded portion do not determine the height of the battery cell, the height dimension of the battery cell can be uniformly managed.

[0247] Hereinafter, a method for manufacturing the above-mentioned battery cell will be described with reference to Figure 21 .

[0248] According to the manufacturing method of the battery cell, first, a can 10 having a first electrode terminal 13 fixed to a bottom member 12, and an electrode assembly 20 having a first current collector plate 31 and a second current collector plate 32 respectively bonded to two axial ends are prepared.

[0249] Next, the electrode assembly 20 is inserted and accommodated in the can 10, and the first current collector plate 31 is oriented toward the bottom member 12. Then, the second current collector plate 32 is positioned at the open end of the can 10. In the process of storing the electrode assembly 20 in the can 10, a first section a of the outer abutting surface 325 of the can connection portion 324 provided on the radially outer edge of the second current collector plate 32 is in close contact with the first inner surface 111 of the side wall member 11.

[0250] Next, the first current collector plate 31 and the first electrode terminal 13 are joined.

[0251] In addition, an electrolyte is injected into the can 10.

[0252] After the electrolyte injection is completed, the open end of the side wall member 11 is covered with the lid 16, and the outer engagement surface 171 and the current collector plate abutment surface 173 provided on the edge of the lid 16 are brought into contact with or opposed to the second inner surface 115 of the side wall member 11 and the lid abutment surface 326 of the second current collector plate 32, respectively.

[0253] In this case, the thickness reduction portion 161 disposed in the form of an inclined surface on the axial inner surface of the lid 16 is brought into contact with the can connection portion 324 of the second current collector plate 32, thereby aligning the lid 16, and the outer abutment surface 325 of the can connection portion 324 can be pressed against the second inner surface 115 of the side wall member 11.

[0254] Next, a laser beam is irradiated from the axially outer side in the axial direction onto the abutting portion of the second inner surface 115 of the side wall member 11 and the outer engagement surface 171 of the lid 16, thereby performing welding.

[0255] In this case, the protruding portion 117 of the side wall member 11 that protrudes further outward than the lid 16 in the axial direction can be melted and flow into the welded portion between the inner surface of the side wall member 11 and the outer engagement surface 171 of the lid 16.

[0256] When performing welding, a preliminary welding process can be first performed, and then main welding can be performed.

[0257] In the preliminary welding process, the laser beam is irradiated from the axially outer side in the axial direction onto the abutting portion of the inner surface of the side wall member 11 and the outer engagement surface 171 of the lid 16 at a plurality of positions spaced apart from each other in the circumferential direction, thereby forming a plurality of preliminary welded portions W3 by welding the inner surface of the side wall member 11 and the outer engagement surface 171 of the lid 16. The preliminary welding is performed at a low output, thereby suppressing the generation of a discontinuous surface.

[0258] The preliminary welding can be omitted.

[0259] Next, in the main welding process, the laser beam is continuously irradiated from the axially outer side in the axial direction along the circumferential direction onto the abutting portion of the inner surface of the side wall member 11 and the outer engagement surface 171 of the lid 16 to form a second welded portion W2 in which at least the inner surface of the side wall member 11 and the outer engagement surface 171 of the lid 16 are welded together.

[0260] In this case, in the process of forming the second welding portion W2, at least one of the energy density and the scanning speed in the laser output, irradiation area, and irradiation area can be adjusted to intermittently increase the welding depth and / or the welding cross-sectional area so as to weld the inner surface of the side wall member 11, the outer joint surface 171 of the cover 16, and the can connection portion 324 of the second current collector plate 32 together, thereby forming the first welding portion W1 as a triple welding portion.

[0261] As Figure 22 shown, the battery cell 72 manufactured by the above welding structure and welding process can be accommodated in the housing 71 of the battery pack 70. The battery pack 70 can be configured using battery modules as an intermediate assembly form, or can be directly configured without battery modules as shown.

[0262] Since the above battery cell 72 has a large volume, there is no particular difficulty in implementing the battery pack 70 even without using the intermediate structure of the battery module. In addition, the battery cell 72 has a low internal resistance and a higher energy density. Therefore, the energy density of the battery pack 70 equipped with the battery cell 72 can be made higher.

[0263] The battery pack 70 having an increased energy density can store the same amount of energy while reducing its volume and weight. Therefore, as Figure 23 shown, if the battery pack 70 applying the battery cell 72 is installed in a vehicle (for example, a vehicle 80 using electricity as an energy source), the driving range per unit energy of the vehicle can be further increased.

[0264] It should be understood that the above embodiments are exemplary in all aspects and do not limit the present disclosure, and the scope of the present disclosure will be indicated by the claims described separately rather than the detailed description described above. In addition, the scope of the present disclosure should be construed to include all changes and variations derived from equivalent concepts, as well as the meaning and scope of the claims to be described separately.

[0265] As described above, although the present disclosure has been described with reference to limited embodiments and drawings, the present disclosure is not limited thereto, and various modifications and changes are clearly possible within the technical concept of the present disclosure for those skilled in the art. In addition, even if the effects of the configuration according to the present disclosure are not explicitly described while explaining the embodiments of the present disclosure, the effects predictable through this configuration are clearly necessarily accepted.

[0266] [Description of Reference Numerals]

[0267] 10: Can

[0268] 11: Side Wall Member

[0269] 111: First Inner Surface

[0270] 113: Inner diameter expansion part

[0271] 115: Second inner surface

[0272] 117: Protrusion part

[0273] 12: Bottom member

[0274] 13: First electrode terminal (positive terminal)

[0275] 14: Washer

[0276] 15: Second electrode terminal

[0277] 16: Cover

[0278] 160: Cover body

[0279] 161: Thickness reduction part

[0280] 17: Bonding part

[0281] 171: Outer bonding surface

[0282] 173: Current collector plate abutting surface

[0283] 19: Insulator

[0284] 20: Electrode assembly

[0285] 21: First electrode

[0286] 22: Second electrode

[0287] 23: Metal foil

[0288] 24: Active material layer

[0289] 25: Coated area

[0290] 26: Uncoated area

[0291] 27: Electrode joint (notch joint)

[0292] 28: Diaphragm

[0293] 31: First current collector plate (positive current collector plate)

[0294] 312: Terminal connection part

[0295] 313: Edge part

[0296] 314: Electrode connection part

[0297] 32: Second current collector plate (negative current collector plate)

[0298] 321: Inner ring part

[0299] 322: Hole

[0300] 323: Electrode connector connection part

[0301] 324: Tank connection part

[0302] 325: Outer abutting surface

[0303] 326: Cover abutting surface

[0304] 327: Bending part

[0305] 70: Battery pack

[0306] 71: Outer shell

[0307] 72: Battery cell

[0308] 80: Vehicle

[0309] A: Welding device

[0310] B: Laser irradiation area

[0311] C: Laser scanning path

[0312] W1: First welding part

[0313] W2: Second welding part

[0314] W3: Third welding part

Claims

1. A battery cell, comprising: a can including a bottom member, a side wall member connected to the bottom member and extending in an axial direction, and a cover configured to cover an open end provided at one axial end of the side wall member; as well as an electrode assembly, the electrode assembly being housed in the can, wherein the can connection portion is disposed on an edge of a current collecting plate electrically connected to an electrode of the electrode assembly to electrically contact the can, wherein a plurality of first welding portions are formed to be spaced apart from each other in the circumferential direction, in which the edge of the opening end of the side wall member, the edge of the cover and the tank connecting portion are welded together, and The second welding portion is continuously formed along the circumferential direction between two first welding portions adjacent to each other in the circumferential direction so as to be connected to the two first welding portions, and in the second welding portion, at least the edge of the opening end of the side wall member and the edge of the cover are welded.

2. The battery cell according to claim 1, in, third welding portions in which an edge of the opening end of the side wall member and an edge of the cover are welded are formed to be spaced apart from each other in the circumferential direction, and The welding depth of the second welding portion is greater than the welding depth of the third welding portion, or the cross-sectional area of ​​the second welding portion is greater than the cross-sectional area of ​​the third welding portion when viewed in the circumferential direction.

3. The battery cell according to claim 2, in, In the circumferential direction, the section where the third welded portion is formed does not overlap with the section where the first welded portion is formed.

4. The battery cell according to claim 2, in, In the circumferential direction, a section where the third weld portion is formed overlaps a section where the second weld portion is formed.

5. The battery cell according to claim 1, in, The welding depth of the first welding portion is greater than the welding depth of the second welding portion, or Wherein, when viewed in the circumferential direction, the cross-sectional area of ​​the first welding portion is greater than the cross-sectional area of ​​the second welding portion.

6. The battery cell according to claim 1, in, The tank connection portion comprises: an outer abutment surface in which a first section as at least a part of the axial section faces and contacts the inner surface of the sidewall member in a radial direction; and a cover abutment surface configured to face and contact an inner surface of the cover in the axial direction, and Wherein, the cover includes an outer bonding surface configured to face or contact the inner surface of the side wall member in the radial direction.

7. The battery cell according to claim 6, in, The cover includes a current collecting plate abutment surface defined by an axial inner surface of the cover and configured to face and contact the cover abutment surface of the tank connecting portion of the current collecting plate in the axial direction, and Wherein, the outer bonding surface of the cover is disposed axially more outward and radially more outward than the current collecting plate abutting surface.

8. The battery cell according to claim 7, in, The cover includes an inclined surface disposed radially more inward than the current collecting plate abutting surface on the axial inner surface of the cover, and the inclined surface extends axially inward as the inclined surface is closer to the radial inner side, and The inclined surface contacts at least one corner forming a boundary between an axially outer end and a radially inner end of the tank connecting portion of the current collecting plate.

9. The battery cell according to claim 6, in, The outer diameter of the first section of the outer abutment surface is greater than the inner diameter of the inner surface of the sidewall member in contact with the first section, so that the first section of the outer abutment surface is forcibly pressed toward the sidewall member.

10. The battery cell according to claim 6, in, The sidewall member comprises at one axial end: an inner diameter expansion portion, the inner diameter expansion portion having an inclined shape so that the inner diameter of the side wall member increases; a first inner surface disposed axially inwardly based on the inner diameter expansion portion; and a second inner surface, the second inner surface is axially arranged outwardly based on the inner diameter expansion portion, and the inner diameter of the second inner surface is greater than the inner diameter of the first inner surface, wherein the outer abutment surface of the tank connection portion faces or contacts the second inner surface, and Wherein, the outer bonding surface of the cover faces or contacts the second inner surface.

11. The battery cell according to claim 10, in, The first section of the outer abutment surface has an outer diameter that is greater than an inner diameter of the first inner surface.

12. The battery cell according to claim 10, in, The outer diameter of the outer abutment surface corresponds to or is smaller than the inner diameter of the second inner surface.

13. The battery cell according to claim 6, in, A protruding portion is provided at one axial end of the side wall member to protrude further outward than the cover in the axial direction, and wherein the protruding portion melts to flow into a welding portion of the inner surface of the side wall member and the outer joining surface of the cover.

14. The battery cell according to claim 13, in, The height of the battery cell is defined by the surface of the cover.

15. A method for manufacturing a battery cell, the battery cell comprising: a can including a bottom member, a side wall member connected to the bottom member and extending in an axial direction, and a cover configured to cover an open end provided at one axial end of the side wall member; an electrode assembly housed in the can; and a current collecting plate coupled to one side of the electrode assembly, the method comprising the following steps: A first step is to bring an outer abutment surface of a tank connection portion provided at a radially outer edge of the current collecting plate into contact with an inner surface at the open end of the side wall member; A second step of covering the open end of the side wall member with the cover so that an outer joining surface provided on an edge of the cover faces the inner surface of the side wall member in a radial direction and the inner surface of the cover contacts the cover abutting surface of the current collecting plate in an axial direction; and The third step is to irradiate the laser beam continuously in the circumferential direction, irradiate the laser beam from the axial outside in the axial direction onto the abutment portion between the inner surface of the side wall member and the outer joining surface of the cover, and perform welding so that the first welding portion and the second welding portion alternate, in the first welding portion, the inner surface of the side wall member, the outer joining surface of the cover and the tank connecting portion of the collecting plate are welded together, and in the second welding portion, at least the inner surface of the side wall member and the outer joining surface of the cover are welded together.

16. The method for manufacturing a battery cell according to claim 15, comprising the following steps: The first welded portions and the second welded portions are alternately formed such that the circumferential length of the second welded portions is formed to be longer than the circumferential length of the first welded portions.

17. The method for manufacturing a battery cell according to claim 15, further comprising the following steps: The preliminary welding step performed between the second step and the third step forms a plurality of third welding portions in which the edge of the opening end of the side wall member and the edge of the cover are welded to be spaced apart from each other in the circumferential direction.

18. The method for manufacturing a battery cell according to claim 17, in, The third step includes the step of melting a protruding portion of the side wall member that protrudes further outward than the cover in the axial direction to flow into a welded portion of the inner surface of the side wall member and the outer joining surface of the cover.

19. The method for manufacturing a battery cell according to claim 15, in, The intensity of the laser beam irradiated on the section for welding the first weld part or the energy density of the laser irradiation area of ​​the laser beam is stronger or higher than the intensity of the laser beam irradiated on the section for welding the second weld part or the energy density of the laser irradiation area of ​​the laser beam.

20. The method for manufacturing a battery cell according to claim 19, in, The moving speed of the irradiation area of ​​the laser beam irradiated onto the section for welding the first weld portion and the moving speed of the irradiation area of ​​the laser beam irradiated onto the section for welding the second weld portion are constant.

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