Cylindrical secondary battery

Abstract

Embodiments of the present invention relate to a cylindrical secondary battery. The present invention comprises: an electrode assembly having a shape wound in one direction, comprising a negative electrode plate, a positive electrode plate, and a separator interposed between the negative electrode plate and the positive electrode plate; a metal finishing tape attached to the outer surface of the electrode assembly to wrap at least a portion of the electrode assembly; a cylindrical can having one side open to accommodate the electrode assembly together with an electrolyte; and a cap assembly coupled to the open side of the can to seal the can. According to the present invention, applying a metallic tape to the winding finish portion of an electrode assembly has the effect of improving the quality variation of the substrate finish structure caused by long-axis variation. In addition, the metallic tape acts as an additional terminal tab (substrate tab), thereby having the effect of improving cell performance variation.

Description

Technology Field

[0001] An embodiment of the present invention relates to a cylindrical secondary battery capable of improving cell performance variation. Background Technology

[0002] Generally, a cylindrical secondary battery includes a cylindrical electrode assembly, a cylindrical can that accommodates the electrode assembly and electrolyte, and a cap assembly that is coupled to the upper opening of the can to seal the can and allow current generated from the electrode assembly to flow to an external device. Among these, the electrode assembly is formed by rolling a negative electrode substrate and a positive electrode substrate into a cylindrical shape, and attaching tape or the like to prevent the rolled ends from unraveling.

[0003] With the recent demand for high-output, high-capacity batteries, there is a growing need to efficiently design the internal space of cylindrical cans. Accordingly, there is a need to improve the substrate finishing structure.

[0004] The information described above disclosed in the background technology of this invention is intended only to enhance understanding of the background of the present invention and may therefore include information that does not constitute prior art. The problem to be solved

[0005] The objective of the present invention is to provide a cylindrical secondary battery capable of improving cell performance variation. means of solving the problem

[0006] A cylindrical secondary battery according to an embodiment of the present invention comprises: an electrode assembly having a shape wound in one direction, comprising a negative electrode plate, a positive electrode plate, and a separator interposed between the negative electrode plate and the positive electrode plate; a metal finishing tape attached to the outer surface of the electrode assembly to wrap at least a portion of the electrode assembly; a cylindrical can having one side open to accommodate the electrode assembly together with an electrolyte; and a cap assembly coupled to the open side of the can to seal the can.

[0007] The above-mentioned sealing tape includes a metal region that contacts one side of the inner surface of the can, and an adhesive region formed on the metal region and attached to the electrode assembly.

[0008] The adhesive area is characterized by being repeatedly formed on the metal area with a preset shape and spacing.

[0009] The adhesive area above includes at least one of a vertical line, a horizontal line, a grid, or a dot shape.

[0010] The above-mentioned finishing tape is characterized by being attached to at least a portion of the outer end, which is the wound end of the electrode assembly.

[0011] The length (L2) of the finishing tape is characterized by being 10 to 100% of the length (L1) of the electrode assembly based on the winding axis direction of the electrode assembly.

[0012] The above finishing tape is characterized by being a plurality of individual tapes. Effects of the invention

[0013] According to an embodiment of the present invention, applying a metallic tape to the winding finish portion of an electrode assembly has the effect of improving the quality variation of the substrate finish structure caused by long-axis variation. In addition, the metallic tape acts as an additional terminal tab (substrate tab), thereby having the effect of improving cell performance variation. Brief explanation of the drawing

[0014] Figure 1 is a cross-sectional view illustrating a typical cylindrical secondary battery. FIG. 2 is a simplified plan view illustrating an electrode assembly according to one embodiment of the present invention. FIG. 3 is a simplified perspective view of an electrode assembly according to FIG. 1. Figure 4 is a plan view showing an enlarged view of one area of ​​Figure 3. FIGS. 5 to 7 are perspective views briefly illustrating the attachment forms of a finishing tape according to various embodiments of the present invention. FIGS. 8 to 10 are plan views illustrating parts of a finishing tape according to various embodiments of the present invention. Specific details for implementing the invention

[0015] The embodiments of the present invention are provided to more fully explain the invention to those skilled in the art, and the following embodiments may be modified in various different forms, and the scope of the invention is not limited to the following embodiments. Rather, these embodiments are provided to make the disclosure more faithful and complete and to fully convey the spirit of the invention to those skilled in the art.

[0016] Additionally, in the drawings below, the thickness or size of each layer is exaggerated for convenience and clarity of explanation, and like reference numerals in the drawings refer to like elements. As used herein, the term "and / or" includes any one of the listed items and all combinations of one or more thereof. Furthermore, in this specification, the meaning of "connected" refers not only to cases where Member A and Member B are directly connected, but also to cases where Member C is interposed between Member A and Member B so that Member A and Member B are indirectly connected.

[0017] The terms used herein are for describing specific embodiments and are not intended to limit the invention. As used herein, the singular form may include the plural form unless the context clearly indicates otherwise. Additionally, as used herein, "comprise, include" and / or "comprising, including" specify the presence of the mentioned features, numbers, steps, actions, parts, elements, and / or groups thereof, and do not exclude the presence or addition of one or more other features, numbers, actions, parts, elements, and / or groups.

[0018] Although terms such as "first," "second," etc. are used in this specification to describe various components, parts, regions, layers, and / or parts, it is obvious that these components, parts, regions, layers, and / or parts should not be limited by these terms. These terms are used solely to distinguish one component, part, region, layer, or part from another region, layer, or part. Accordingly, the first component, part, region, layer, or part described below may refer to the second component, part, region, layer, or part without departing from the teachings of the present invention.

[0019] Spatial terms such as "beneath," "below," "lower," "above," and "upper" may be used to facilitate understanding of one element or feature depicted in the drawings and another element or feature. These spatial terms are intended to facilitate understanding of the invention according to various process or usage conditions of the invention and are not intended to limit the invention. For example, if an element or feature in the drawings is inverted, an element or feature described as "beneath" or "below" becomes "upper" or "on top." Therefore, "beneath" is a concept that encompasses "upper" or "below."

[0020] Hereinafter, a cylindrical secondary battery according to an embodiment of the present invention will be described in detail with reference to the attached drawings.

[0021] Figure 1 is a cross-sectional view illustrating a typical cylindrical secondary battery.

[0022] As illustrated in FIG. 1, a general cylindrical secondary battery (10) may include a cylindrical can (100) having an opening formed at one end in the longitudinal direction, an electrode assembly (300) accommodated inside the can, and a cap assembly (500) inserted into the opening.

[0023] The can (100) includes a circular bottom portion (110) and a side portion (130) extending upward from the bottom portion (110), and the upper part of the side portion (130) is in an open shape (hereinafter referred to as the opening). In the manufacturing process of the secondary battery (B), an electrode assembly (300) is inserted into the can (100) along with an electrolyte through the opening of the can (100). The can (100) may be formed of steel, steel alloy, nickel-plated steel, nickel-plated steel alloy, aluminum, aluminum alloy, or an equivalent thereof, but the material is not limited thereto.

[0024] A cap assembly (500) is inserted into the opening of the can (100). An anti-detachment structure may be formed on the upper part of the can (100) so that the inserted cap assembly (500) does not escape to the outside through the opening of the can (100). For example, the anti-detachment structure may be a beading part (132) and a crimping part (134).

[0025] The electrode assembly (300) includes a negative electrode plate (310) coated with a negative electrode active material (e.g., graphite, carbon, etc.) on a negative electrode substrate (negative electrode non-coated portion), a positive electrode plate (320) coated with a positive electrode active material (e.g., transition metal oxide (LiCoO2, LiNiO2, LiMn2O4, etc.)), and a separator (330) disposed between the negative electrode plate (310) and the positive electrode plate (320) to prevent short circuits and allow only the movement of lithium ions. The negative electrode plate (310), the positive electrode plate (320), and the separator (330) can be wound into a roughly cylindrical shape and then secured with a finishing tape (see FIG. 2, described later) to maintain the wound state. In this state, the electrode assembly (300) can be accommodated inside a can (100).

[0026] The negative substrate of the negative plate (310) may be copper (Cu) or nickel (Ni) foil, the positive substrate of the positive plate (320) may be aluminum (Al) foil, and the separator (330) may be polyethylene (PE) or polypropylene (PP), but the above materials are not limited in the present invention. A negative tab (340) extending downward by a certain length may be welded to the negative plate (310), and a positive tab (350) extending upward by a certain length may be welded to the positive plate (320), but the reverse is also possible. The negative tab (340) may be made of copper or nickel, and the positive tab (350) may be made of aluminum, but the above materials are not limited in the present invention. The negative tab (340) may be welded to the bottom portion (110) of the can (100), in which case the can (100) may operate as a negative electrode. Conversely, the positive tab (350) can be welded to the bottom portion (110) of the can (100), in which case the can (100) can operate as a positive electrode.

[0027] Additionally, a first insulating plate (360) and a second insulating plate (370) may be provided on the upper and lower portions of the electrode assembly (300). The first insulating plate (360) prevents the positive plate (320) from electrically contacting the bottom portion (110) of the can (100), and the second insulating plate (370) prevents the negative plate (310) from electrically contacting the cap assembly (500).

[0028] Meanwhile, the aforementioned finishing tape (400) is attached to the wound end of the electrode assembly (300) so that the electrode assembly (300) does not unravel while wound.

[0029] FIG. 2 is a simplified plan view illustrating an electrode assembly according to one embodiment of the present invention. FIG. 3 is a simplified perspective view illustrating an electrode assembly according to FIG. 1. FIG. 4 is a plan view showing an enlarged area of ​​FIG. 3. FIG. 5 to 7 are simplified perspective views illustrating attachment forms of a finishing tape according to various embodiments of the present invention.

[0030] As illustrated in FIGS. 2 and 3, the electrode assembly (300) is wound in a cylindrical shape with a separator (330) interposed between the negative plate (310) and the positive plate (320). Assuming that a virtual central axis exists in the longitudinal direction of the electrode assembly (300), this central axis becomes the winding axis (A). The electrode assembly (300) is secured by a finishing tape (400) so as not to unravel. For convenience, the winding start portion of the electrode assembly (300) is defined as the inner end portion of the electrode assembly (300), and the winding end portion is defined as the outer end portion. The finishing tape (400) is attached to cover a portion based on the winding axis direction of the electrode assembly (300), and is attached to wrap around the outer surface of the electrode assembly (300). Accordingly, the finishing tape (400) may be formed in a rectangular shape and attached in a wound form around the outer surface of the electrode assembly (300), or may be formed in a cylindrical shape and inserted into the outer surface of the electrode assembly (300).

[0031] If the length in the winding axis direction of the electrode assembly (300) is denoted as L1, the length L2 of the finishing tape (400) based on the same direction may be 10 to 100% of L1. For example, as shown in FIG. 3, the length L2 of the finishing tape (400) may be approximately 60% of the length of L1. Or, as shown in FIG. 5, the length L2 of the finishing tape (400a) may be approximately 80% of the length of L1, and as shown in FIG. 6, the length L2 of the finishing tape (400b) may be approximately 20% of L1. Or, as shown in FIG. 7, the finishing tape (400c) may be composed of a plurality of tapes having a length L2 that is approximately 20% of the length of L1 and attached to the electrode assembly (300). In this case, the finishing tape (400c) may be spaced apart from each other and may be attached adjacent to the negative tab (340) and the positive tab (350). Alternatively, the finishing tape (400c) may be positioned close to the middle part of L1.

[0032] Additionally, as illustrated in FIG. 4, the finishing tape (400) may include a metal region (410) and an adhesive region (420). The metal region (410) may be made of the same or similar material as the electrode plate placed at the outermost edge in the last turn of the electrode assembly (300). For example, as in FIG. 1, the negative tab (340) is in contact with the can (100) so that the polarity of the can (100) becomes negative, so the negative plate (310) may be placed at the outermost edge in FIG. 2. In this case, the metal region (410) may be made of the same or similar material as the substrate of the negative plate (310). In this case, the metal region (410) may be any one of copper, nickel, or an alloy of copper and nickel.

[0033] The adhesive region (420) can be formed by applying, coating, or attaching an adhesive material onto the metal region (410). The adhesive region (420) can be made of a material that reacts with the electrolyte within the operating temperature range of the secondary battery to have adhesive properties. For example, the adhesive region (420) can be made of an acrylic or PVdF-based binder material.

[0034] At this time, the adhesive region (420) serves to fix the electrode assembly (300) so that the outer end of the electrode assembly (300) does not unravel while in a wound state. In addition, since the metal region (410) is a metal material that is a conductor, it can come into contact with the can (100) and function as a substrate tab. That is, since the metal region (410) is made of the same material as the negative electrode substrate, the negative electrode substrate of the can (100) and the negative electrode plate (310) can be electrically connected by the metal region (410). That is, since the metal region (410) enables the movement of electrons, it can function as a tab. If the diameter of the electrode assembly (300) is small, the can (100) and the negative electrode substrate cannot come into contact, so it cannot function as a tab. However, if the finishing tape (400) has a metal region (410), the problem of the negative electrode substrate not coming into contact with the can (100) and thus not functioning as a substrate tab due to changes in diameter can be improved.

[0035] The adhesive area (420) can be formed on the metal area (410) with a predetermined spacing. For example, as shown in FIG. 4, the adhesive area (420) can be formed on the metal area (410) in the form of a plurality of vertical lines having a predetermined width. Thus, the finishing tape (400) can be in a form where the metal area (410) and the adhesive area (420) are arranged alternately. That is, the shape of the metal area (410) is revealed only in the parts where the adhesive area (420) is not formed.

[0036] However, the arrangement of the metal region (410) and the adhesive region (420) is not limited to the above-described embodiment.

[0037] FIGS. 8 to 10 are plan views illustrating parts of a finishing tape according to various embodiments of the present invention.

[0038] As illustrated in FIG. 8, in another embodiment of the present invention, the finishing tape (400d) may have adhesive areas (420d) formed in the form of a plurality of horizontal lines having a predetermined width on a metal area (410d). Thus, the finishing tape (400d) may be in a form where the metal area (410d) and the adhesive area (420d) are arranged alternately.

[0039] Alternatively, as illustrated in FIG. 9, in another embodiment of the present invention, the finishing tape (400e) may have an adhesive area (420e) formed in a grid shape on a metal area (410e). Thus, it may appear as if the metal area (410e) is arranged on the adhesive area (420e) in a plurality of rectangular shapes.

[0040] Alternatively, as illustrated in FIG. 10, in another embodiment of the present invention, the finishing tape (400f) may have adhesive areas (420f) formed in the shape of a plurality of dots having a predetermined size on a metal area (410f). The adhesive areas (420f) may be arranged on the metal area (410f) at regular intervals.

[0041] However, the form of the finishing tape (400d~400f) is not limited to the embodiments described above.

[0042] As described above, applying a metallic finishing tape to the winding finish of the electrode assembly has the effect of improving the quality variation of the substrate finish structure caused by long-axis variation. In addition, the metallic finishing tape acts as an additional terminal tab (substrate tab), which has the effect of improving cell performance variation.

[0043] The above description is merely one embodiment for implementing the present invention, and the present invention is not limited to the above-described embodiment. The technical spirit of the present invention extends to the scope in which various modifications can be made by anyone with ordinary knowledge in the field to which the invention belongs, without departing from the essence of the invention as claimed in the following patent claims. Explanation of the symbols

[0044] 10: Cylindrical secondary battery 100: Can 300: Electrode assembly 310: Cathode plate 320: Positive plate 330: Separator 400a~400f: Finishing tape 410: Metal area 420: Adhesion area

Claims

Claim 1 A cylindrical secondary battery comprising: an electrode assembly having a negative electrode plate, a positive electrode plate, and a separator interposed between the negative electrode plate and the positive electrode plate, and having a shape wound in one direction; a metal finishing tape attached to the outer surface of the electrode assembly to wrap at least a portion of the electrode assembly; a cylindrical can having one side open to accommodate the electrode assembly together with an electrolyte; and a cap assembly coupled to the open side of the can to seal the can, wherein the finishing tape comprises a metal region and a plurality of adhesive regions spaced apart from each other on the metal region. Claim 2 A cylindrical secondary battery according to claim 1, wherein the metal region contacts one side of the inner circumferential surface of the can, and the adhesive region is attached to the electrode assembly. Claim 3 In claim 2, the adhesive region is repeatedly formed on the metal region to have a preset shape and spacing, forming a cylindrical secondary battery. Claim 4 In claim 3, the adhesive area comprises at least one of a vertical line, a horizontal line, a grid, and a dot shape, forming a cylindrical secondary battery. Claim 5 In claim 1, the finishing tape is attached to at least a portion of the outer end, which is the wound end of the electrode assembly, of a cylindrical secondary battery. Claim 6 A cylindrical secondary battery according to claim 1, wherein the length (L2) of the finishing tape is 10 to 100% of the length (L1) of the electrode assembly based on the winding axis direction of the electrode assembly. Claim 7 A cylindrical secondary battery according to claim 6, characterized in that the sealing tape is a plurality of pieces. Claim 8 A cylindrical secondary battery according to claim 1, wherein the metal region is connected to an electrode plate positioned at the outermost edge in the last turn of the electrode assembly. Claim 9 A cylindrical secondary battery according to claim 8, wherein the metal region is made of the same material as the electrode plate placed at the outermost edge in the last turn of the electrode assembly. Claim 10 A cylindrical secondary battery according to claim 1, wherein the negative electrode plate comprises the entire outer surface of the electrode assembly. Claim 11 A cylindrical secondary battery according to claim 1, wherein the adhesive region is made of a material having adhesive properties that reacts with the electrolyte. Claim 12 A cylindrical secondary battery according to claim 1, wherein the adhesive region is made of a material having adhesive properties that reacts with the electrolyte.

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