Secondary battery and method for manufacturing the same

Abstract

Some embodiments of a secondary battery may include an electrode assembly with an electrode tab bundle on one side, electrode leads welded to the electrode tab bundle, and an adhesive layer located between the electrode tab bundle and the electrode leads and below the front edge of the electrode leads. Some embodiments of a secondary battery can prevent the electrode tab bundle from breaking and thus prevent a decrease in the performance of the secondary battery.

Description

Technical Field

[0001] This disclosure claims the benefit of priority based on Korean Patent Application No. 10-2024-0042963 filed on March 29, 2024, and all the contents of Korean Patent Application No. 10-2024-0042963 are incorporated by reference into this disclosure.

[0002] The present invention relates to a secondary battery and a method for manufacturing the same.

Background Art

[0003] In recent years, in order to reduce carbon emissions while reducing dependence on fossil fuels, there has been an increasing interest in secondary batteries that can be repeatedly used for a long time through recharge. In particular, lithium secondary batteries among secondary batteries are secondary batteries that use lithium ions as ions, are excellent in energy density and lifespan, and research and development on them are actively being conducted. As a result, lithium secondary batteries are being used in various fields such as portable electronic devices, vehicles, and ESS.

[0004] Lithium secondary batteries are classified into cylindrical, prismatic, and pouch types according to the shape of the battery case. Pouch-type lithium secondary batteries use a film as the battery case, and the assembly process is simpler than that of cylindrical and prismatic types that use a can as the battery case, and they are excellent in heat dissipation performance, lifespan performance, and energy density. Also, the designs of small and medium to large-sized pouch-type lithium secondary batteries are almost similar, which is also advantageous in leading the market. As a result, many developments have been made on pouch-type lithium secondary batteries.

[0005] In pouch-type lithium secondary batteries, an electrode assembly consisting of multiple positive electrodes, multiple negative electrodes, and multiple separator films is typically located inside a film. On one side of the electrode assembly, there is an electrode tab bundle to which multiple electrode tabs are welded. The electrode tab bundle is welded to the electrode lead and electrically connected to it. However, during the manufacturing process of the electrode lead, such as by mold notching, burrs are generated on one side. Conventionally, workers would visually check which side of the electrode lead was free of burrs and insert the electrode lead so that this side was in contact with the electrode tab bundle.

[0006] However, if a worker made a mistake, the burrs on the electrode leads would come into contact with the electrode tab bundle, as shown in Figure 1. Therefore, conventionally, there was a risk that the electrode tab bundle could be torn due to worker error. If a secondary battery was manufactured with a torn electrode tab bundle, the performance of the secondary battery would inevitably deteriorate. [Overview of the project] [Problems that the invention aims to solve]

[0007] The technical concept of this invention aims to solve the problem of a secondary battery in which the electrode tab bundle does not break and performance does not deteriorate. Another problem that the technical concept of this invention aims to solve is to provide a method for manufacturing a secondary battery that can prevent the electrode tab bundle from breaking. [Means for solving the problem]

[0008] Some embodiments of the present invention that can solve the above problems are as follows.

[0009] A secondary battery according to some embodiments may include an electrode assembly with an electrode tab bundle on one side, an electrode lead welded to the electrode tab bundle, and an adhesive layer located between the electrode tab bundle and the electrode lead, and below the front edge of the electrode lead.

[0010] In some embodiments, the distance from the adhesive layer to the multiple electrodes included in the electrode assembly may be shorter than the distance from the welded portion to the multiple electrodes included in the electrode assembly.

[0011] In some embodiments, the adhesive layer may be separated from the weld.

[0012] In some embodiments, the adhesive layer may be non-conductive.

[0013] In some embodiments, the adhesive layer may have portions that do not overlap with the electrode leads in a direction parallel to the thickness direction of the electrode leads.

[0014] A method for manufacturing a secondary battery according to some embodiments includes a first step of providing an electrode assembly including an electrode tab bundle on one side; a second step of applying an adhesive layer to the electrode tab bundle; and a third step of welding the electrode tab bundle to an electrode lead, wherein the second step is performed before the third step, and the adhesive layer in the second step can be applied so as to be located below the front edge of the electrode lead to be welded in the third step.

[0015] In some embodiments, the adhesive layer can be applied in the second step such that the distance from the adhesive layer to the multiple electrodes included in the electrode assembly is shorter than the distance from the weld formed by welding in the third step to the multiple electrodes included in the electrode assembly.

[0016] In some embodiments, the welding in the third step may not be performed on the adhesive layer.

[0017] In some embodiments, the adhesive layer in the second step may be non-conductive.

[0018] In some embodiments, the adhesive layer can be applied in the second step such that there is a portion that does not overlap with the electrode lead to be welded in the third step, in a direction parallel to the thickness direction of the electrode lead.

[0019] In some embodiments, the welding in the third step may be one or more of laser welding, resistance welding, and ultrasonic welding.

Advantages of the Invention

[0020] Some embodiments of the present invention can prevent the electrode tab bundle from breaking and the performance of the secondary battery from degrading. Some embodiments of the present invention can prevent the electrode tab bundle from breaking and can prevent the position of the electrode lead before welding with the electrode tab bundle from being changed after welding.

[0021] The effects of the embodiments of the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly derived and understood by those with ordinary knowledge in the technical field to which the embodiments of the present invention belong from the following description. That is, the unintended effects associated with implementing the embodiments of the present invention can also be clearly derived and understood by those with ordinary knowledge in the technical field to which the embodiments of the present invention belong.

Brief Description of the Drawings

[0022] [Figure 1] The drawing for explaining the conventional problem. [Figure 2] A schematic side view for explaining some embodiments. [Figure 3] A schematic top view for explaining some embodiments.

Modes for Carrying Out the Invention

[0023] The terms and words used in this specification should not be construed as being limited to their ordinary or dictionary meanings, but can be construed as meanings consistent with the technical idea of the present invention based on the principle that the inventor can appropriately define the meanings of the terms and words in order to explain his own invention in the best way.

[0024] In this specification, terms such as "comprising" and "having" are intended to specify that the features, numbers, steps, operations, components, parts, or combinations thereof described in the specification exist, and can be understood as not precluding the existence or addition possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof. Also, when a part such as a layer, film, region, or plate is said to be "on" another part, this includes not only the case where it is directly on the other part, but also the case where there is another part in between. Conversely, when a part such as a layer, film, region, or plate is said to be "under" another part, it includes not only the case where it is directly under the other part, but also the case where there is another part in between.

[0025] The embodiments and drawings are merely examples of the present invention and do not represent all of the technical ideas of the present invention, so there can be various equivalents and modifications that can replace them.

[0026] Also, in the description of the present invention, when it is determined that a specific description of a known configuration or function may obscure the gist of the present invention, the detailed description thereof is omitted.

[0027] The drawings are provided to more fully explain the present invention to an ordinary technician, so the shapes, sizes, and numbers of the components in the drawings may be exaggerated, omitted, or shown schematically for a clearer explanation. The shapes, sizes, ratios, and numbers of each component in the drawings do not fully reflect the actual shapes, sizes, ratios, and numbers of each component.

[0028] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0029] One aspect of the present invention relates to a secondary battery.

[0030] Figure 2 is a schematic side view for explaining some embodiments. Figure 3 is a schematic top view for explaining some embodiments.

[0031] In this specification, the direction substantially parallel to the longitudinal direction of the electrode lead 120 is defined as the X direction, the direction substantially parallel to the thickness direction of the electrode lead 120 is defined as the Y direction, and the direction substantially parallel to the width direction of the electrode lead 120 is defined as the Z direction.

[0032] The electrode assembly 100 includes an electrode tab bundle 110 on one side. The electrode tab bundle 110 may consist of multiple electrode tabs that have been ultrasonically welded, laser welded, or resistance welded. In some embodiments, the electrode assembly 100 may consist of multiple positive electrodes and multiple negative electrodes stacked with a separator membrane in between.

[0033] The electrode tab bundle 110 may be a positive electrode tab bundle and / or a negative electrode tab bundle. In some embodiments, the electrode assembly 100 may include a positive electrode tab bundle on one side and a negative electrode tab bundle on the other side. In some embodiments, the electrode assembly 100 may include a positive electrode tab bundle and a negative electrode tab bundle on one side, and the positive electrode tab bundle and the negative electrode tab bundle may be separated from each other. As a non-limiting example, the positive electrode tab bundle may be an aluminum tab bundle. As a non-limiting example, the negative electrode tab bundle may be a copper tab bundle.

[0034] The electrode tab bundle 110 is welded to the electrode lead 120. The electrode tab bundle 110 and the electrode lead 120 are melted during welding and then cooled to form a welded joint 140. The welded joint 140 electrically connects the electrode tab bundle 110 and the electrode lead 120.

[0035] The electrode leads 120 may be positive and / or negative leads. In non-limiting examples, the positive lead may be an aluminum lead or a nickel lead. In non-limiting examples, the negative lead may be a copper lead or a nickel lead. In some embodiments, the electrode leads 120 may be surrounded by insulating tape 150. The insulating tape 150 can maintain the sealing of the battery case while insulating the electrode leads 120 from the battery case by being heat-fused to the battery case when the electrode assembly 100 is housed inside the battery case and the battery case is sealed.

[0036] The adhesive layer 130 is located between the electrode tab bundle 110 and the electrode lead 120, and below the front edge 120E of the electrode lead 120. The adhesive layer 130 prevents the electrode tab bundle 110 from being torn by the burr of the electrode lead 120, even if the worker is unable to detect the burr of the electrode lead 120 and the burr of the electrode lead 120 comes into contact with the electrode tab bundle 110. This prevents a decrease in the performance of the secondary battery. In most cases, the burr of the electrode lead 120 is formed on the front edge 120E of the electrode lead 120. Therefore, it may be preferable for the adhesive layer 130 to be located below the front edge 120E of the electrode lead 120.

[0037] In some embodiments, the distance from the adhesive layer 130 to the multiple electrodes included in the electrode assembly 100 may be shorter than the distance from the welded portion 140 to the multiple electrodes included in the electrode assembly 100. As described above, since the burrs of the electrode lead 120 are formed in a region close to the multiple electrodes included in the electrode assembly 100, it may be preferable that the distance from the adhesive layer 130 to the multiple electrodes included in the electrode assembly 100 be shorter than the distance from the welded portion 140 to the multiple electrodes included in the electrode assembly 100.

[0038] In some embodiments, the adhesive layer 130 may be nonconductive. If the adhesive layer 130 is nonconductive, it may be preferable that the adhesive layer 130 be separated from the weld 140. This is because if the nonconductive adhesive layer 130 overlaps with the weld 140, the electrical connection between the electrode lead 120 and the electrode tab bundle 110 may become poor.

[0039] In some embodiments, the adhesive layer 130 may include one or more of the following: cyanoacrylate-based instant adhesives; hot melt adhesives such as ethylene vinyl acetate-based, polyolefin-based, styrene block copolymer-based, polyamide-based, polyester-based, and urethane-based adhesives; and pressure-sensitive adhesives such as acrylic resin, butyl rubber, and vinyl acetate.

[0040] The thickness of the adhesive layer 130 is sufficient to cover the burrs. In some embodiments, the thickness of the adhesive layer 130 can be in the range of approximately 350 μm to approximately 500 μm.

[0041] In some embodiments, the adhesive layer 130 may have portions that do not overlap with the electrode lead 120 in the Y direction. The burrs on the electrode lead 120 may be formed so as not to overlap with the electrode lead 120 in the Y direction. Therefore, it may be preferable for the adhesive layer 130 to have portions that do not overlap with the electrode lead 120 in the Y direction.

[0042] Another aspect of the present invention relates to a method for manufacturing a secondary battery.

[0043] In some embodiments, a method for manufacturing a secondary battery includes a first step of providing an electrode assembly 100 including an electrode tab bundle 110 on one side; a second step of applying an adhesive layer 130 to the electrode tab bundle 110; and a third step of welding the electrode tab bundle 110 to an electrode lead 120, wherein the second step may be performed before the third step, and the adhesive layer 130 in the second step may be applied so as to be located below the front edge 120E of the electrode lead 120 that will be welded in the third step. Because the electrode tab bundle 110 is welded to the electrode lead 120 after the adhesive layer 130 has been applied to the electrode tab bundle 110, it is possible to prevent the electrode tab bundle 110 from being torn by the burrs of the electrode lead 120, even if the worker cannot detect burrs on the electrode lead 120 and the burrs of the electrode lead 120 come into contact with the electrode tab bundle 110. Furthermore, since the electrode tab bundle 110 is bonded to the electrode lead 120 via the adhesive layer 130 before the electrode tab bundle 110 is welded to the electrode lead 120, it is possible to prevent the position of the electrode lead from changing, and the welding between the electrode tab bundle 110 and the electrode lead 120 can be performed more precisely. As described above, in most cases, burrs on the electrode lead 120 are formed on the front edge 120E of the electrode lead 120. Therefore, it may be preferable in the second step to apply the adhesive layer 130 so that it is located below the front edge 120E of the electrode lead 120 that will be welded in the third step.

[0044] In some embodiments, the adhesive layer 130 can be applied such that the distance from the adhesive layer 130 to the multiple electrodes included in the electrode assembly 100 is shorter than the distance from the welded portion 140 formed by welding in the third step to the multiple electrodes included in the electrode assembly 100. As described above, since the burrs of the electrode lead 120 are formed in areas close to the multiple electrodes included in the electrode assembly 100, it may be preferable in the second step to apply the adhesive layer 130 such that the distance from the adhesive layer 130 to the multiple electrodes included in the electrode assembly 100 is shorter than the distance from the welded portion 140 formed by welding in the third step to the multiple electrodes included in the electrode assembly 100.

[0045] In some embodiments, the adhesive layer 130 can be applied in the second step such that there is a portion that does not overlap with the electrode lead 120 to be welded in the third step in the Y direction. As described above, the burrs on the electrode lead 120 may be formed so as not to overlap with the electrode lead 120 in the Y direction. Therefore, it may be preferable in the second step to apply the adhesive layer 130 so that there is a portion that does not overlap with the electrode lead 120 to be welded in the third step in the Y direction.

[0046] In some embodiments, welding may not be performed on the adhesive layer 130 in the third step. As described above, if the adhesive layer 130 is non-conductive, it may be preferable not to weld to the adhesive layer 130 in the third step in order to ensure good electrical connection between the electrode lead 120 and the electrode tab bundle 110.

[0047] In some embodiments, welding in the third step may be one or more of laser welding, resistance welding, and ultrasonic welding. As a non-limiting example, ultrasonic welding may be performed by scanning ultrasound at less than 20 kHz, 15 kHz or less, or 10 kHz or less. As a non-limiting example, laser welding may be performed at 10 7 W / cm 2 This can be done at the following energy densities.

[0048] The above description is for illustrative purposes only. The scope of the present invention should be interpreted by the claims, and all technical ideas within the same or equivalent scope should be interpreted as being included within the scope of the present invention. [Explanation of symbols]

[0049] 100: Electrode assembly 110: Electrode tab bundle 120: Electrode Lead 120E: Front edge of electrode lead 130: Adhesive layer 140: Welded section 150: Insulating tape

Claims

1. An electrode assembly including an electrode tab bundle on one side, Electrode leads welded to the electrode tab bundle, It is located between the electrode tab bundle and the electrode lead, A secondary battery comprising an adhesive layer located beneath the front edge of the electrode lead.

2. The secondary battery according to claim 1, wherein the distance from the adhesive layer to the plurality of electrodes included in the electrode assembly is shorter than the distance from the welded portion to the plurality of electrodes included in the electrode assembly.

3. The secondary battery according to claim 1, wherein the adhesive layer is separated from the welded portion.

4. The secondary battery according to claim 1, wherein the adhesive layer is non-conductive.

5. The secondary battery according to claim 1, wherein the adhesive layer has portions that do not overlap with the electrode leads in a direction parallel to the thickness direction of the electrode leads.

6. The first step is to provide an electrode assembly including an electrode tab bundle on one side, The second step is to apply an adhesive layer to the electrode tab bundle, The third step includes welding the electrode tab bundle to the electrode lead, The aforementioned second step is performed before the aforementioned third step. A method for manufacturing a secondary battery, comprising applying the adhesive layer in the second step so that it is located below the front edge of the electrode lead to be welded in the third step.

7. The method for manufacturing a secondary battery according to claim 6, wherein in the second step, the adhesive layer is applied such that the distance from the adhesive layer to the plurality of electrodes included in the electrode assembly is shorter than the distance from the welded portion formed by welding in the third step to the plurality of electrodes included in the electrode assembly.

8. The method for manufacturing a secondary battery according to claim 6, wherein in the third step, the welding is not performed on the adhesive layer.

9. The method for manufacturing a secondary battery according to claim 6, wherein the adhesive layer in the second step is non-conductive.

10. The method for manufacturing a secondary battery according to claim 6, wherein in the second step, the adhesive layer is applied such that there is a portion that does not overlap with the electrode lead to be welded in the third step in a direction parallel to the thickness direction of the electrode lead.

11. The method for manufacturing a secondary battery according to claim 6, wherein the welding in the third step is one or more of laser welding, resistance welding, and ultrasonic welding.

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