Battery cell and battery cell manufacturing method

Abstract

According to the present disclosure, a battery cell manufacturing device can be provided, the device comprising: a moving unit for transporting a battery cell that includes a cell tab on which a barcode is displayed; and a recognition device which faces the movement path of the battery cell transported by the moving unit, and which recognizes the barcode, wherein the recognition device includes a guide unit, which sprays air toward the cell tab so as to prevent the cell tab from bending.

Description

Battery cell and battery cell manufacturing method

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0154348 dated November 4, 2024, and all contents disclosed in the document of said Korean patent application are incorporated herein as part of this specification.

[0002] The present disclosure relates to a battery cell and a method for manufacturing a battery cell.

[0003] Battery cells (secondary batteries) are rechargeable and dischargeable, so they are widely used in mobile devices such as digital cameras, mobile phones, and laptops. In particular, they are recently attracting attention as an energy source for electric vehicles and Energy Storage Systems (ESS).

[0004] Battery cells can be classified according to the shape of the case into cylindrical battery cells or prismatic battery cells in which the electrode assembly is embedded in a cylindrical or prismatic metal can, and pouch-type batteries in which the electrode assembly is embedded in a pouch-type case made of a film sheet.

[0005] Cylindrical battery cells include rivet terminals that serve to transmit current from the electrode assembly to the outside. During the manufacturing process of cylindrical battery cells, a welding process is performed between the current collector plate and the rivet terminals to electrically connect the rivet terminals and the current collector plate.

[0006] Meanwhile, ultrasonic welding may be applied in the process of welding current collector plates and rivet terminals. During this process, burrs—foreign substances formed by the deformation of a portion of the current collector plate due to friction between the welding rod and the plate—may form on the plate where the welding rod makes contact. These burrs can occur in a small, thin, thread-like form and are highly likely to detach from the current collector plate. If the burrs detach from the current collector plate and remain inside the battery cell, it may cause defects in the battery cell.

[0007] The present disclosure is designed to solve at least some of the problems of the prior art as described above. In a method for manufacturing a battery cell, the burr generated during the welding process is formed into a bulk form, thereby reducing the possibility of the burr detaching from the current collector plate.

[0008] A battery cell manufacturing method according to one embodiment of the present disclosure comprises an alignment step of butting a first current collector plate electrically connected to an electrode assembly and a rivet terminal together and aligning them, and a welding step of welding the rivet terminal and the first current collector plate by ultrasonic welding, wherein the rivet terminal includes a terminal groove in which a portion of the surface facing the first current collector plate is recessed inward, and the welding step may be a step of butting a welding rod at a welding point of the first current collector plate positioned to correspond to the terminal groove.

[0009] According to one embodiment, the first width, which is the depth of the terminal groove, may be equal to or smaller than the second width, which is the thickness of the first current collector plate.

[0010] According to one embodiment, the diameter of the terminal groove may be larger than the diameter of the front end of the welding rod.

[0011] According to one embodiment, the diameter of the terminal groove may be equal to or larger than the sum of the diameter of the tip of the welding rod and twice the second width.

[0012] According to one embodiment, the welding step may include a pressing step of pressing the first collector plate toward the terminal groove with the tip of the welding rod, and a friction step of rotating or vibrating the welding rod to cause friction between the first collector plate and the rivet terminal.

[0013] According to one embodiment, the first collector plate before the pressurization step is performed may be flat.

[0014] According to one embodiment, the first current collector plate may include a protrusion that is partially bent after the welding step and received in the terminal groove.

[0015] According to one embodiment, the protrusion may include a shape corresponding to the terminal groove.

[0016] A battery cell according to one embodiment of the present disclosure comprises an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, a can accommodating the electrode assembly, a rivet terminal electrically connected to the electrode assembly and at least a portion of which is accommodating the can, and a first current collector plate electrically connected to the electrode assembly and the rivet terminal, wherein the rivet terminal includes a terminal groove in which a portion of the surface facing the first current collector plate is recessed inward, and a first width, which is the depth of the terminal groove, is equal to or smaller than a second width, which is the thickness of the first current collector plate, and the first current collector plate may include a protrusion in which at least a portion is bent and accommodating the terminal groove.

[0017] According to one embodiment, at least a portion of the protrusion of the first collector plate may be ultrasonically welded to the rivet terminal.

[0018] According to one embodiment, the protrusion may include a shape corresponding to the terminal groove.

[0019] According to one embodiment, the protrusion may be formed by bending the first collector plate during the ultrasonic welding process.

[0020] According to one embodiment of the present disclosure, the possibility of burrs detaching from the current collector plate of a battery cell is reduced, thereby reducing defects in the battery cell.

[0021] FIG. 1 is a cross-sectional view illustrating a cross-section of a battery cell according to one embodiment of the present disclosure.

[0022] FIG. 2 is a cross-sectional view illustrating a welding step during the manufacturing process of a battery cell according to one embodiment of the present disclosure.

[0023] FIG. 3 is a flowchart illustrating a method for manufacturing a battery cell according to one embodiment of the present disclosure.

[0024] Figure 4 is a cross-sectional view illustrating the process of welding a current collector plate and a rivet terminal during the manufacturing process of a conventional battery cell.

[0025] FIG. 5 is a cross-sectional view illustrating the process of welding a first current collector plate and a rivet terminal during the manufacturing process of a battery cell according to one embodiment of the present disclosure.

[0026] Figure 6 is an enlarged cross-sectional view of A in Figure 5.

[0027] FIG. 7 is a cross-sectional view illustrating the process of welding a first current collector plate and a rivet terminal during the manufacturing process of a battery cell according to one embodiment of the present disclosure.

[0028] Figure 8 is an enlarged cross-sectional view of B in Figure 7.

[0029] FIG. 9(a) is an enlarged photograph of one side of a current collector plate welded to a rivet terminal of a conventional battery cell, and FIG. 9(b) is an enlarged photograph of one side of a current collector plate welded to a rivet terminal of a battery cell according to one embodiment of the present disclosure.

[0030] FIG. 10 (a) is a three-dimensional view of one side of a current collector plate welded to a rivet terminal of a conventional battery cell, and FIG. 10 (b) is a three-dimensional view of one side of a current collector plate welded to a rivet terminal of a battery cell according to one embodiment of the present disclosure.

[0031] In describing the embodiments of the present disclosure, the terms used have been selected to be as widely used as possible, taking into account their functions within the present disclosure; however, these terms may vary depending on the intent of those skilled in the art, case law, the emergence of new technologies, etc. Additionally, in specific cases, terms may be selected at the applicant's discretion, and in such cases, their meanings may be described in detail in the relevant explanatory section. Therefore, the terms used in the present disclosure are not merely names, but may be defined based on their meanings and the overall content of the present disclosure.

[0032] The suffix "part" for components used in this specification is assigned or used interchangeably solely for the sake of ease of drafting the specification and may not have a distinct meaning or role in itself. Furthermore, in describing the embodiments included in this disclosure, if it is determined that a detailed description of related prior art could obscure the essence of the embodiments included in this disclosure, such detailed description may be omitted. Additionally, the attached drawings are intended only to facilitate understanding of the embodiments included in this disclosure, and the technical concept of this disclosure is not limited by the attached drawings; it should be understood that the technical concept and scope of this disclosure include all modifications, equivalents, and substitutions.

[0033] Terms including ordinal numbers, such as first, second, etc., may be used to describe various components, but said components are not limited by said terms, and said terms may be used only for the purpose of distinguishing one component from another.

[0034] When it is stated that a component is "connected" or "connected" to another component, it can be understood that it may be directly connected or connected to that other component, or that there may be other components in between. On the other hand, when it is stated that a component is "directly connected" or "directly connected" to another component, it can be understood that there are no other components in between.

[0035] In this specification, singular expressions may include plural expressions unless the context clearly indicates otherwise.

[0036] Terms such as "comprising" or "having" as used in this specification are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should not be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0037] The expression "at least one of a, b, and c" as described in this specification may include 'a alone', 'b alone', 'c alone', 'a and b', 'a and c', 'b and c', or 'a, b, and c all'.

[0038] Embodiments of the present disclosure are described below with reference to the attached drawings so that those skilled in the art can easily implement them. However, the present disclosure may be embodied in various different forms and is not limited to the embodiments described herein.

[0039] Embodiments of the present disclosure will be described in detail below with reference to the drawings.

[0040] FIG. 1 is a cross-sectional view illustrating a cross-section of a battery cell (1) according to one embodiment of the present disclosure, and FIG. 2 is a cross-sectional view illustrating a welding step (S300) during the manufacturing process of a battery cell (1) according to one embodiment of the present disclosure.

[0041] Referring to FIGS. 1 and 2, a battery cell (1) according to one embodiment of the present disclosure may include an electrode assembly (100). The electrode assembly (100) may include a positive electrode (110), a negative electrode (120), and a separator (130). The separator (130) may be interposed between the positive electrode (110) and the negative electrode (120). The electrode assembly (100) may have a plurality of positive electrodes (110), negative electrodes (120), and separators (130) stacked alternately. The electrode assembly (100) may be wound to form a jelly roll. At this time, a central hole (140), which is a predetermined empty space, may be formed in the center of the electrode assembly (100). The central hole (140) may be a central empty space formed during the winding process of the electrode assembly (100) and may be formed along the longitudinal direction of the electrode assembly (100).

[0042] A battery cell (1) according to one embodiment of the present disclosure may include a can (200). The can (200) may accommodate an electrode assembly (100). The can (200) may be composed of a conductive material through which current can flow. The can (200) may be configured to be cylindrical to accommodate an electrode assembly (100) in the form of a jelly roll inside. The can (200) may be configured to seal an internal space. The can (200) may include a first surface (210) facing upward and a second surface (220) facing downward. The can (200) may be sealed after accommodating the electrode assembly (100) and the electrolyte. The first surface (210) may seal the upper part of the can (200) with a rivet terminal (500), which will be described later, inserted therein. The second surface (220) may be composed of a cap plate to seal the lower part of the can (200).

[0043] In describing the battery cell (1) of the present disclosure in this specification, the electrode assembly (100) and the can (200) are described as a jelly roll and a cylinder, respectively, but their shapes may be appropriately modified to achieve the purpose of the present disclosure. For example, the electrode assembly (100) may have a unidirectional stacked shape, and the can (200) may be formed as a rectangular shape.

[0044] The battery cell (1) of the present disclosure may include a rivet terminal (500). The rivet terminal (500) may be electrically connected to an electrode assembly (100). A first current collector plate (300), to be described later, may be interposed between the rivet terminal (500) and the electrode assembly (100). The rivet terminal (500) may be composed of a conductive material to allow electricity to flow. At least a portion of the rivet terminal (500) may be received by a can (200). In other words, at least a portion of the rivet terminal (500) may be exposed to the outside of the can (200). The rivet terminal (500) may be configured to discharge electrical energy of the electrode assembly (100) to the outside.

[0045] The battery cell (1) of the present disclosure may include a current collector plate (300, 400). The current collector plate (300, 400) may be electrically connected to the negative electrode (120) or the positive electrode (110) of the electrode assembly (100). The current collector plate (300, 400) may include a first current collector plate (300) and a second current collector plate (400). The first current collector plate (300) may be electrically connected to the positive electrode (110) of the electrode assembly (100), and the second current collector plate (400) may be electrically connected to the negative electrode (120) of the electrode assembly (100). However, the case in which the first current collector plate (300) is connected to the negative electrode (120) and the second current collector plate (400) is connected to the positive electrode (110) is not excluded. The first current collector plate (300) is electrically connected to the electrode assembly (100) and can be electrically connected to the rivet terminal (500). For example, the first current collector plate (300) can be welded to a plurality of positive electrodes (110) of the electrode assembly (100) and can be welded to the rivet terminal (500). At this time, the second current collector plate (400) can be electrically connected to a part of the can (200).

[0046] Hereinafter, the specific shape of the rivet terminal (500) and the first collector plate (300) and the welding step (S300) of welding the rivet terminal (500) and the first collector plate (300) will be described in detail.

[0047] FIG. 3 is a flowchart illustrating a method for manufacturing a battery cell (1) according to an embodiment of the present disclosure; FIG. 4 is a cross-sectional view illustrating the process of welding a current collector plate (300') and a rivet terminal (500') during the manufacturing process of a conventional battery cell (1); FIG. 5 is a cross-sectional view illustrating the process of welding a first current collector plate (300) and a rivet terminal (500) during the manufacturing process of a battery cell (1) according to an embodiment of the present disclosure; FIG. 6 is an enlarged cross-sectional view illustrating A of FIG. 5; FIG. 7 is a cross-sectional view illustrating the process of welding a first current collector plate (300) and a rivet terminal (500) during the manufacturing process of a battery cell (1) according to an embodiment of the present disclosure; FIG. 8 is an enlarged cross-sectional view illustrating B of FIG. 7; FIG. 9 (a) is a photograph taken by enlarging one side of a current collector plate welded to a rivet terminal (500) of a conventional battery cell (1); FIG. Figure 9(b) is a magnified photograph of one side of a current collector plate welded to a rivet terminal (500) of a battery cell (1) according to one embodiment of the present disclosure, Figure 10(a) is a three-dimensional photograph of one side of a current collector plate welded to a rivet terminal (500) of a conventional battery cell (1), and Figure 10(b) is a three-dimensional photograph of one side of a current collector plate welded to a rivet terminal (500) of a battery cell (1) according to one embodiment of the present disclosure.

[0048] FIGS. 5 and FIGS. 7 illustrate a welding step (S300), and the process of FIGS. 5 and FIGS. 7 can be performed in sequence.

[0049] With reference to FIGS. 3 to 10 and FIGS. 1 to 2, a battery cell (1) and a method for manufacturing the battery cell (1) according to one embodiment of the present disclosure will be described in detail.

[0050] A method for manufacturing a battery cell (1) according to one embodiment of the present disclosure may include an alignment step (S200). A shearing process (S100) may be performed prior to performing the alignment step (S200). For example, the shearing process (S100) may be a step of inserting an electrode assembly (100) into a can (200) or inserting a rivet terminal (500) into a can (200). The alignment step (S200) may be a step of aligning a first current collector plate (300) electrically connected to the electrode assembly (100) and a rivet terminal (500) by butting them against each other. FIG. 5 may illustrate the state after the alignment step (S200) is performed. The first current collector plate (300) may include a welding point (310) to which a welding rod (600) contacts, and the rivet terminal (500) may include a terminal groove (550) to be described later. The alignment step (S200) may be a step in which the welding point (310) and the terminal groove (550) of the rivet terminal (500) are aligned side by side, and the rivet terminal (500) and the first collector plate (300) are butted against each other.

[0051] A method for manufacturing a battery cell (1) according to one embodiment of the present disclosure may include a welding step (S300). The welding step (S300) may be a step of welding a rivet terminal (500) and a first current collector plate (300). At this time, the welding method may be ultrasonic welding. Ultrasonic welding may be a method of joining two materials by causing friction between two materials with a welding rod (600). At this time, ultrasonic welding may cause friction through the vibration or rotation of the welding rod (600) while the welding rod (600) is in contact with at least one of the materials to be welded. The front end (610) of the welding rod in contact with the material to be welded may include various shapes to prevent slipping. Referring to FIGS. 9 and 10, a grid pattern may be formed on one side of the welded first current collector plate (300) by welding, such as the front end (610) of the welding rod. However, since this shape is merely an example, it is not necessarily limited to a grid pattern.

[0052] Referring to FIGS. 1 and 5, a rivet terminal (500) according to one embodiment of the present disclosure may include a terminal head (510), a terminal shaft (520), a terminal base (530), and a terminal wing (540). The terminal head (510) may be an area that protrudes upward from the can (200) and is exposed. The terminal shaft (520) may be an axis extending downward from the terminal head (510) and may penetrate the first surface (210), which is the upper surface of the can (200). The terminal base (530) may be an area that protrudes downward and is a part that contacts the first collector plate (300). The terminal wing (540) may be a part that protrudes to the side of the terminal shaft (520) and is caught on one surface of the can (200) so that the rivet terminal (500) inserted into the can (200) does not detach from the can (200).

[0053] Referring to FIGS. 5 and 6, a rivet terminal (500) according to one embodiment of the present disclosure may include a terminal groove (550). The terminal groove (550) may be formed in a region facing the first collector plate (300). The terminal groove (550) may be formed by the aforementioned region being recessed inward. The inner side referred to herein may mean the inner side of the rivet terminal (500).

[0054] A welding step (S300) according to one embodiment of the present disclosure may be a step of butting a welding rod (600) against a welding point (310) of a first collector plate (300) positioned to correspond to a terminal groove (550). The welding point (310) may be a portion where the welding rod (600) is seated and is positioned to correspond to the terminal groove (550). A portion of the first collector plate (300) including the welding point (310) may be deformed and melted by friction and / or pressure by the welding rod (600) and fused with the rivet terminal (500).

[0055] For example, a welding step (S300) according to one embodiment of the present disclosure may include a pressurizing step (S310) and a friction step (S320). Referring to FIGS. 5 and 6, the pressurizing step (S310) may be a step of pressing the first collector plate (300) toward the terminal groove (550) with the tip (610) of the welding rod. The first collector plate (300) before the pressurizing step (S310) is performed may be flat. Referring to FIGS. 7 and 8, the friction step (S320) may be a step of rotating or vibrating the welding rod (600) to cause friction between the first collector plate (300) and the rivet terminal (500).

[0056] According to one embodiment of the present disclosure, the first collector plate (300) may form a protrusion (320) by means of a pressurizing step (S310) and / or a friction step (S320). At least a portion of the first collector plate (300) corresponding to the terminal groove (550), which was flat, may be bent to form a protrusion (320) that is received in the terminal groove (550). That is, the protrusion (320) may be a portion formed by bending the first collector plate (300) during the ultrasonic welding process. At least a portion of the protrusion (320) may be ultrasonically welded to the first collector plate (300).

[0057] A first collector plate (300) according to one embodiment of the present disclosure may include a protrusion (320) after a welding step (S300). The protrusion (320) is received in a terminal groove (550) and may include a shape corresponding to the terminal groove (550). The protrusion (320) may be deformed to fit into the terminal groove (550) by the pressure and / or frictional force of the welding rod (600). However, a slight gap between the protrusion (320) and the terminal groove (550) that may occur during the production process may be allowed.

[0058] In a method for manufacturing a battery cell (1) according to one embodiment of the present disclosure, a subsequent process (S400) may be performed after a welding step (S300). For example, the subsequent process (S400) may be a step of injecting an electrolyte into the interior of a can (200) or sealing a second surface (220) on the bottom of a can (200).

[0059] Referring to FIG. 6, the first width (t1), which is the depth of the terminal groove (550) according to one embodiment of the present disclosure, may be equal to or smaller than the second width (t2) of the first collector plate (300). If the first width (t1) is larger than the second width (t2), the first collector plate (300) may be plastically deformed during the welding process and cut before welding. That is, the area of ​​the first collector plate (300) corresponding to the terminal groove (550) may be cut because it is excessively sunk into the inner side of the terminal groove (550) by the welding rod (600). Therefore, the first width (t1) may be formed to be equal to or smaller than the second width (t2) to prevent this phenomenon.

[0060] Referring to FIG. 8, the diameter (d1) of the terminal groove (550) according to one embodiment of the present disclosure may be larger than the diameter (d2) of the tip (610) of the welding rod. For example, if the cross-section of the tip (610) of the welding rod is circular, the cross-section of the terminal groove (550) may also be formed circular. In this case, the diameter (d1) of the terminal groove (550) may be formed larger than the diameter (d2) of the tip (610) of the welding rod so that the tip (610) of the welding rod can be sufficiently accommodated in the terminal groove (550) during the welding process. Specifically, the diameter (d1) of the terminal groove (550) may be equal to or larger than the size of the sum of the diameter (d2) of the tip (610) of the welding rod and twice the second width (t2). The diameter (d1) of the terminal groove (550) may have a sufficient length to accommodate the tip of the weld and the protrusion (320) inside the terminal groove (550).

[0061] Referring to FIG. 4, since the conventional rivet terminal (500') does not include a terminal groove (550), ultrasonic welding was performed by butting a flat current collector plate (300') against one side of the flat rivet terminal (500'). As a result, it can be confirmed that a small, thin burr (B') like a thread may be generated, as shown in FIG. 9 (a) and FIG. 10 (a). Since such a burr (B') is formed thinly and protrudes upward from the current collector plate, it can be easily detached from the current collector plate (300') and may cause internal defects in the battery cell (1).

[0062] According to the battery cell (1) and the method for manufacturing the battery cell (1) according to one embodiment of the present disclosure, the burr (B) formed during the welding process can be formed in a bulk form. That is, the burr (B) formed by the battery cell (1) and the method for manufacturing the battery cell (1) according to the present disclosure can have sufficient thickness and mass so as not to be easily detached from the first current collector plate (300). Referring to FIG. 9(b) and FIG. 10(b), the burr (B) according to one embodiment of the present disclosure is formed with a thickness and mass greater than that of a conventional burr (B') so that it may not be easily detached from the first current collector plate (300). Therefore, defects in the battery cell (1) that may be caused by the burr (B) can be reduced.

[0063] Although the present disclosure has been illustrated and described in connection with preferred embodiments to illustrate the principles of the present disclosure, the present disclosure is not limited to the configuration and operation as illustrated and described. Rather, those skilled in the art will understand that numerous changes and modifications to the present disclosure are possible without departing from the spirit and scope of the appended claims.

Claims

1. An alignment step of butting a first current collector plate electrically connected to an electrode assembly and a rivet terminal together; and A welding step of welding the above rivet terminal and the above first collector plate by ultrasonic welding; Includes, The above rivet terminal includes a terminal groove in which a portion of the surface facing the first current collector plate is recessed inward, and A battery cell manufacturing method in which the welding step is a step of butting a welding rod against a welding point of the first current collector plate positioned to correspond to the terminal groove.

2. In Paragraph 1, A method for manufacturing a battery cell in which the first width, which is the depth of the terminal groove, is equal to or smaller than the second width, which is the thickness of the first current collector plate.

3. In Paragraph 2, A method for manufacturing a battery cell in which the diameter of the terminal groove is larger than the diameter of the front end of the welding rod.

4. In Paragraph 3, A method for manufacturing a battery cell in which the diameter of the terminal groove is equal to or greater than the size of the sum of the diameter of the tip of the welding rod and twice the second width.

5. In Paragraph 1, The above welding step is, A pressing step of pressing the first collector plate toward the terminal groove with the tip of the welding rod and A method for manufacturing a battery cell comprising a friction step of rotating or vibrating the welding rod to cause friction between the first collector plate and the rivet terminal.

6. In Paragraph 5, A method for manufacturing a battery cell in which the first current collector plate is flat before the above-mentioned pressurization step is performed.

7. In Paragraph 1, A method for manufacturing a battery cell in which the first current collector plate includes a protrusion that is partially bent and received in the terminal groove after the welding step.

8. In Paragraph 7, A method for manufacturing a battery cell in which the above-mentioned protrusion includes a shape corresponding to the above-mentioned terminal groove.

9. An electrode assembly comprising an anode, a cathode, and a separator interposed between the anode and the cathode; A can accommodating the above electrode assembly; A rivet terminal electrically connected to the electrode assembly and having at least a portion accommodated in the can; and A first current collector plate electrically connected to the electrode assembly and the rivet terminal; Includes, The above rivet terminal includes a terminal groove in which a portion of the surface facing the first current collector plate is recessed inward, and The first width, which is the depth of the terminal groove, is equal to or smaller than the second width, which is the thickness of the first collector plate, and The above first collector plate is a battery cell comprising a protrusion that is at least partially bent and received in the terminal groove.

10. In Paragraph 9, The first current collector plate is a battery cell in which at least a portion of the protrusion is ultrasonically welded to the rivet terminal.

11. In Paragraph 9, The above-mentioned protrusion is a battery cell having a shape corresponding to the terminal groove.

12. In Paragraph 9, The above protrusion is a battery cell formed by bending the first collector plate during the ultrasonic welding process.

Images