Secondary battery

Abstract

A secondary battery includes an electrode assembly including a negative electrode plate, a positive electrode plate, and a separator interposed between the negative electrode plate and the positive electrode plate; an adhesive to fix the separator on one surface of the electrode assembly perpendicular to a surface of the separator; a case to accommodate the electrode assembly; a negative electrode lead wire drawn from the negative electrode plate; and a positive electrode lead wire drawn from the positive electrode plate.

Description

Technical Field

[0001] An aspect of the embodiments of this disclosure relates to a secondary battery. Background Technology

[0002] Unlike non-rechargeable primary batteries, secondary batteries can be charged and discharged. Low-capacity secondary batteries are widely used in small portable electronic devices, such as mobile phones and portable cameras, while high-capacity secondary batteries are typically used to power the motors of hybrid vehicles and electric vehicles. Secondary batteries are classified into cylindrical, prismatic, and polymer types based on their external shape. In the case of polymer batteries, the electrode assembly is encased in a pouch, allowing for high energy density and reduced space usage, but potentially making them relatively more susceptible to external shocks.

[0003] The information disclosed in this background section is intended to enhance the understanding of the background technology of this disclosure, and therefore may contain information that does not constitute prior art. Summary of the Invention

[0004] One or more embodiments of this disclosure relate to a secondary battery with improved safety.

[0005] According to one or more embodiments of the present disclosure, a secondary battery includes: an electrode assembly including a negative electrode plate, a positive electrode plate, and a separator between the negative electrode plate and the positive electrode plate; an adhesive on a surface of the electrode assembly perpendicular to the separator for fixing the separator; a housing for housing the electrode assembly; a negative electrode lead extending from the negative electrode plate; and a positive electrode lead extending from the positive electrode plate.

[0006] In one embodiment, the diaphragm may include multiple diaphragms, the electrode assembly may be stacked in the order of negative electrode plate, one of the multiple diaphragms, positive electrode plate and another of the multiple diaphragms, and the adhesive may cover at least two adjacent diaphragms of the multiple diaphragms.

[0007] In one embodiment, at least two adjacent diaphragms may have ends that are clustered together, and an adhesive may be applied to the edges of the ends.

[0008] In one embodiment, the electrode assembly may be wound into an elongated oval shape as viewed in a plane perpendicular to the winding direction of the electrode assembly, having a flat portion defined by two opposing flat outer surfaces, and a curved portion connecting the two opposing flat outer surfaces to each other from one side and the opposite side, respectively, and an adhesive may be located on the flat portion.

[0009] In one embodiment, the adhesive may be spaced apart from the curved portion.

[0010] In one embodiment, the adhesive may be located on the outer portion of the electrode assembly away from the center of the electrode assembly.

[0011] In one embodiment, the adhesive may be spaced apart from the edge of the electrode assembly.

[0012] In one embodiment, the adhesive may be applied along the winding direction of the electrode assembly.

[0013] In one embodiment, the adhesive may be applied in dots.

[0014] In one embodiment, the adhesive may be divided into multiple segments.

[0015] In one embodiment, the adhesive may be located in multiple rows.

[0016] In one embodiment, the adhesive may include a fluorescent material.

[0017] In one embodiment, the adhesive may be applied across the winding direction of the electrode assembly.

[0018] In one embodiment, the adhesive can be applied linearly.

[0019] In one embodiment, the adhesive may cover an area of ​​a surface as a whole. Attached Figure Description

[0020] The above and other aspects and features of this disclosure will become clear from the accompanying drawings and from the following detailed description of exemplary, non-limiting embodiments.

[0021] Figure 1 The diagram schematically illustrates the disassembly state of a secondary battery according to an embodiment of the present disclosure.

[0022] Figure 2 The lower surface of the electrode assembly of a secondary battery according to an embodiment of the present disclosure is schematically shown.

[0023] Figure 3 schematically showing along Figure 2 The cross section taken from line III-III in the diagram.

[0024] Figure 4A This is a view illustrating the drop test results of an electrode assembly for a secondary battery according to an embodiment of the present disclosure.

[0025] Figure 4B This is a view illustrating the drop test results of an electrode assembly for a secondary battery based on a comparative example.

[0026] Figures 5-9 The lower surface of the electrode assembly of a secondary battery according to various other embodiments of the present disclosure is schematically shown. Detailed Implementation

[0027] In the following detailed description, embodiments will be referenced to the accompanying drawings, in which the same reference numerals consistently denote the same elements. However, this disclosure may be embodied in various different forms and should not be construed as being limited to the embodiments illustrated herein. Rather, these embodiments are provided as examples so that this disclosure will be exhaustive and complete, and will fully convey to those skilled in the art the aspects and features of this disclosure. Therefore, processes, elements, and techniques not essential for a full understanding of the aspects and features of this disclosure by those of ordinary skill in the art may not be described. Unless otherwise stated, the same reference numerals denote the same elements throughout the drawings and written description, and therefore redundant descriptions are not required.

[0028] When an embodiment can be implemented differently, the specific process sequence may differ from the described sequence. For example, two consecutively described processes may be performed simultaneously or substantially simultaneously, or they may be performed in the reverse order of the described sequence.

[0029] In the accompanying drawings, for clarity, the relative dimensions, thicknesses, and ratios of elements, layers, and regions may be enlarged and / or simplified. For ease of interpretation, spatial relative terms such as “below,” “under,” “down,” “below,” “above,” and “above” may be used herein to describe the relationship of an element or feature illustrated in the figures to other elements or features. It will be understood that, in addition to the orientations shown in the figures, spatial relative terms are intended to include different orientations of the device in use or operation. For example, if the device in the figures is flipped, an element described as “below,” “under,” or “below” other elements or features is oriented “above” that other element or feature. Thus, the illustrative terms “below” and “below” can include orientations above and below. The device may be oriented in other ways (e.g., rotated 90 degrees or in other orientations) and the spatial relative terms used herein should be interpreted accordingly.

[0030] In the diagram, the x-axis, y-axis, and z-axis are not limited to the three axes of a Cartesian coordinate system and can be interpreted in a broader sense. For example, the x-axis, y-axis, and z-axis can be perpendicular or substantially perpendicular to each other, or they can represent different directions that are not perpendicular to each other.

[0031] It will be understood that although the terms “first,” “second,” “third,” etc., may be used herein to describe various elements, components, regions, layers, and / or sections, these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are used to distinguish one element, component, region, layer, or section from other elements, components, regions, layers, or sections. Therefore, the first element, component, region, layer, or section discussed below may be referred to as the second element, component, region, layer, or section without departing from the spirit and scope of this disclosure.

[0032] It will be understood that when an element or layer is referred to as being "on" other elements or layers, "connected to" or "attached to" other elements or layers, it can be directly on other elements or layers, directly connected to or attached to other elements or layers, or one or more intermediate elements or layers may exist. Similarly, when a layer, area, or element is referred to as being "electrically connected" to other layers, areas, or elements, it can be directly electrically connected to other layers, areas, or elements, and / or can be indirectly electrically connected to one or more intermediate layers, areas, or elements between them. Furthermore, it will be understood that when an element or layer is referred to as being "between two elements or layers," it can be the only element or layer between the two elements or layers, or one or more intermediate elements or layers may exist.

[0033] The terminology used herein is for describing particular embodiments and is not intended to limit this disclosure. As used herein, the singular forms “a” and “an” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprising,” “including,” “having,” and “having,” when used in this specification, expressly indicate the presence of the stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. For example, the expression “A and / or B” means A, B, or A and B. Expressions such as “at least one of…”, when preceding a series of elements, modify the entire series of elements and do not modify individual elements within the series. For example, the expressions “at least one of a, b, or c”, “at least one of a, b, and c”, and “at least one selected from the group including a, b, and c” mean only a, only b, only c, both a and b, both a and c, both b and c, all of a, b, and c, or variations thereof.

[0034] As used herein, the terms “substantially,” “approximately,” and similar terms are used as approximate terms rather than terms of degree and are intended to account for inherent deviations in measured or calculated values ​​that would be recognized by one of ordinary skill in the art. Furthermore, when describing embodiments of this disclosure, the use of “may” means “one or more embodiments of this disclosure.” As used herein, the terms “use” and “be used” may be considered synonymous with the terms “utilize” and “be exploited,” respectively. Additionally, the term “exemplary” is intended to refer to an example or illustration.

[0035] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It will be further understood that terms, such as those defined in common dictionaries, shall be interpreted as having the same meaning as they have in the context of the relevant technology and / or this specification, and shall not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0036] Figure 1 The diagram schematically illustrates the disassembled state of a secondary battery 100 according to an embodiment of the present disclosure. Figure 2 The lower surface of the electrode assembly 110 of a secondary battery 100 according to an embodiment of the present disclosure is schematically shown. Figure 3 schematically showing along Figure 2 The cross section taken from line III-III in the diagram.

[0037] See Figure 1 The secondary battery 100 according to an embodiment of the present disclosure includes an electrode assembly 110 and an adhesive 120 (e.g., see...). Figure 2 ), housing 130, negative electrode lead 140 and positive electrode lead 150.

[0038] The electrode assembly 110 includes a negative electrode plate 111, a positive electrode plate 112, and a diaphragm 113.

[0039] The negative electrode plate 111 may include a negative electrode coated portion and a negative electrode uncoated portion. The negative electrode coated portion may include a negative electrode active material coated on the negative electrode current collector. For example, the negative electrode current collector may include (e.g., may be made of) a thin conductive metal plate, such as copper or nickel foil or mesh, but this disclosure is not limited thereto. The negative electrode uncoated portion may not be coated with a negative electrode active material. For example, the negative electrode active material may include, but is not limited to, carbon-based materials, Si, Sn, tin oxide, tin alloy composites, transition metal oxides, lithium metal nitrites, or metal oxides.

[0040] The positive electrode plate 112 may include a positive electrode coated portion and a positive electrode uncoated portion. The positive electrode coated portion may include a positive electrode active material coated on the positive electrode current collector. For example, the positive electrode current collector may include (e.g., may be made of) a highly conductive thin metal plate, such as aluminum foil or mesh, but this disclosure is not limited thereto. The positive electrode uncoated portion may not be coated with a positive electrode active material. For example, the positive electrode active material may include, but is not limited to, oxometalates, such as composite metal oxides, such as LiCoO2, LiMn2O4, LiNiO2, LiNiMnO2, etc.

[0041] A diaphragm 113 is positioned between the negative electrode plate 111 and the positive electrode plate 112 to prevent or substantially prevent electrical short circuits between them. For example, the diaphragm 113 may include, but is not limited to, polyethylene, polypropylene, or porous copolymers of polyethylene and polypropylene. Furthermore, to effectively prevent electrical short circuits between the negative electrode plate 111 and the positive electrode plate 112, the diaphragm 113 may be formed to be wider than both the negative electrode plate 111 and the positive electrode plate 112 (e.g., in the y-axis direction) (see, for example, [reference needed]). Figure 3 In other words, when the negative electrode plate 111, the diaphragm 113, and the positive electrode plate 112 are stacked in this order, the edge of the diaphragm 113 can protrude much more than the edges of the negative electrode plate 111 and the positive electrode plate 112 (e.g., in the y-axis direction).

[0042] Depending on the manufacturing method, the electrode assembly 110 can be classified into so-called wound type and stacked type. In the accompanying drawings, the electrode assembly 110 is illustrated by way of example as wound type. Hereinafter, for convenience, the electrode assembly 110 will be described in detail in the context of wound type with reference to the accompanying drawings.

[0043] In this configuration, the electrode assembly 110 is stacked in the order of negative electrode plate 111, diaphragm 113, positive electrode plate 112, and diaphragm 113, and then wound around an axis. Here, the electrode assembly 110 can be wound generally into an elongated or elliptical shape when viewed in a plane perpendicular to or substantially perpendicular to the axis. In the following, in the electrode assembly 110, the portion having two opposing flat or substantially flat outer surfaces is referred to as the flat portion 110A, the portion connecting the outer surfaces to each other on one side (e.g., the left side of the figure) is referred to as the first curved portion 110B, and the portion connecting the outer surfaces to each other on the other side (e.g., the right side of the figure) is referred to as the second curved portion 110C (e.g., see...). Figure 2 ).

[0044] Adhesive 120 is applied to a surface of electrode assembly 110 that is perpendicular to or substantially perpendicular to diaphragm 113 (e.g., one end in the y-axis direction), or in other words, the upper surface (e.g., upper end) and / or the lower surface (e.g., lower end) of electrode assembly 110, and is used to secure diaphragm 113. Although adhesive 120 is illustrated as being applied to the lower surface of electrode assembly 110, adhesive 120 may also be applied to the upper surface of electrode assembly 110. For convenience, referring to the accompanying drawings, adhesive 120 will be described in detail as being applied to the lower surface of electrode assembly 110. However, adhesive 120 applied to the upper surface of electrode assembly 110 may be the same as or substantially the same as adhesive 120 applied to the lower surface of electrode assembly 110, and therefore its redundant description need not be repeated.

[0045] Adhesive 120 may be applied to cover at least two adjacent diaphragms 113 to secure the diaphragms 113 together.

[0046] More specifically, the diaphragm 113 may be assembled together on the lower surface of the electrode assembly (e.g., in the y-axis direction), and the adhesive 120 may be applied to the edges of the diaphragm 113 (e.g., see...). Figure 3 Therefore, it is possible to prevent or substantially prevent the adhesive 120 from flowing into the electrode assembly 110 and unintentionally contaminating the negative electrode plate 111 and the positive electrode plate 112.

[0047] Here, due to the curvature of the first curved portion 110B and the second curved portion 110C, it may be difficult to collect (e.g., aggregate) the diaphragm 113 uniformly or substantially uniformly. Therefore, for ease of manufacture, an adhesive 120 may be applied to the flat portion 110A. For example, the adhesive 120 may be applied to be spaced approximately 4 mm from the first curved portion 110B and the second curved portion 110C.

[0048] However, in another embodiment, adhesive 120 may be applied to the first curved portion 110B and / or the second curved portion 110C.

[0049] Furthermore, in the event of an external impact, the diaphragm 113 at the outer portion of the electrode assembly 110 may be more prone to deformation or damage compared to the diaphragm 113 at the center. Therefore, it may be necessary to apply the adhesive 120 closer to the outer portion of the electrode assembly 110 (e.g., in the y-axis direction). However, when the adhesive 120 flows down one side of the electrode assembly 110 from its upper and / or lower surfaces, it may be difficult to insert the electrode assembly 110 into the housing 130 in subsequent processes. Therefore, it may be necessary to apply the adhesive 120 slightly spaced from the edges of the electrode assembly 110. For example, the adhesive 120 may be applied to be spaced approximately 0.1 to 0.2 mm from the edges of the electrode assembly 110.

[0050] However, in another embodiment, the adhesive 120 may be applied to the center of the electrode assembly 110, the adhesive 120 may be applied adjacent to the edge of the electrode assembly 110, and / or may be applied on the edge of the electrode assembly 110.

[0051] In addition, to more firmly secure the diaphragm 113 as a whole, the adhesive 120 may be applied along the winding direction (e.g., the direction in which the edges of the diaphragm 113 are connected to each other).

[0052] In this regard, in the accompanying drawings, the adhesive 120 is illustrated as being applied in the form of dots, but this disclosure is not limited thereto, and in another embodiment, the adhesive 120 may be applied linearly (e.g., along the winding direction).

[0053] In addition, Figure 2 In this embodiment, the adhesive 120 is illustrated as being divided into a total of three segments at the flat portion 110A (e.g., in or on the flat portion 110A), or in other words, divided into a segment 120B adjacent to the first curved portion 110B, a segment 120C adjacent to the second curved portion 110C, and a segment 120A in between, and then applied. However, in another embodiment, for example, the adhesive 120 may be divided into a total of two segments, such as a segment 120B adjacent to the first curved portion 110B and a segment 120C adjacent to the second curved portion 110C, and then applied. Furthermore, the adhesive 120 may also be divided into two or more segments and applied to only one of the two or more segments, or the adhesive 120 may be applied continuously to these segments from the segment 120B adjacent to the first curved portion 110B to the segment 120C adjacent to the second curved portion 110C.

[0054] In addition, Figure 2In this embodiment, adhesive 120 is illustrated as being applied in two rows. However, in another embodiment, to reduce the amount of adhesive used, adhesive 120 may be applied in one row, or to further secure the diaphragm 113 at the center, adhesive 120 may be applied in three or more rows.

[0055] The adhesive 120 may include a fluorescent material. In this case, visual inspection can be performed while the adhesive is in the applied state by irradiating it with ultraviolet light in a subsequent process to determine whether the adhesive is contaminated by whether it emits light. As another example, for visual inspection, the adhesive 120 itself may have a color different from that of the electrode assembly 110 and / or the colors of other adjacent components.

[0056] The housing 130 houses the electrode assembly 110. More specifically, the housing 130 includes a first pouch member 131 primarily surrounding (e.g., around its periphery) one side of the electrode assembly 110, and a second pouch member 132 primarily surrounding (e.g., around its periphery) the opposite side of the electrode assembly 110. The first pouch member 131 and the second pouch member 132 may be connected (e.g., joined or attached to each other) along their edges. The first pouch member 131 and the second pouch member 132 may be manufactured separately and connected to each other, or they may be manufactured integrally so that they can be folded relative to each other. An embodiment of the latter is illustrated in... Figure 1 middle.

[0057] The negative electrode lead 140 extends from the negative electrode plate 111 of the electrode assembly 110 and passes between the first bag member 131 and the second bag member 132. In this case, to prevent or substantially prevent electrical short circuits with the housing 130, the negative electrode lead 140 may include an insulating member in the portion that contacts the housing 130.

[0058] The positive electrode lead 150 extends from the positive electrode plate 112 of the electrode assembly 110 and passes between the first bag member 131 and the second bag member 132. In this case, to prevent or substantially prevent electrical short circuits with the housing 130, the positive electrode lead 150 may include an insulating member in the portion that contacts the housing 130.

[0059] Figure 4A This is a view illustrating the drop test results of an electrode assembly 110 for a secondary battery 100 according to an embodiment of the present disclosure. Figure 4B This is a view illustrating the drop test results of an electrode assembly for a secondary battery (e.g., an electrode assembly to which no adhesive has been applied, on its upper surface (e.g., the upper end) and / or lower surface (e.g., the lower end)) according to a comparative example.

[0060] The drop test was performed under the same conditions on the electrode assembly 110 of the secondary battery 100 according to an embodiment of the present disclosure and the electrode assembly according to a comparative example, performing 48 repeated free drops from a height of 1.52m.

[0061] As a result, in the electrode assembly 110 of the secondary battery 100 according to an embodiment of the present disclosure, no deformation, wrinkling or curling of the separator occurs.

[0062] However, in the electrode assembly according to the comparative example, diaphragm curling and exposure of the negative electrode plate were observed (e.g., see...). Figure 4B (The part circled in dashed circles). In this case, it causes an electrical short circuit between the negative electrode plate and the positive electrode plate.

[0063] Therefore, through drop testing, it is confirmed that the electrode assembly 110 can be more effectively protected from external impacts in relation to the secondary battery 100 according to an embodiment of the present disclosure.

[0064] Figures 5 to 9 The lower surface of the electrode assembly of a secondary battery according to various other embodiments of the present disclosure is schematically shown.

[0065] Figures 5 to 9 The embodiments shown may differ from those described above. Figures 1 to 3 The described embodiment differs in that the adhesive 120 can be applied across the winding direction of the electrode assembly, rather than along the winding direction of the electrode assembly 110.

[0066] For more details, see Figure 5 In one embodiment, an adhesive (e.g., a pattern represented by thick lines) is applied between two opposing flat or substantially flat outer surfaces of the electrode assembly, and is applied perpendicular to or substantially perpendicular to the winding direction of the electrode assembly. For example, suppose... Figure 2 In the embodiment shown, the adhesive 120 is applied in a "-" shape. Figure 5 In the illustrated embodiment, the adhesive 120 can be considered to be applied in an "l" shape. Similar to the embodiments described above, the adhesive can be applied in dots or linearly.

[0067] See Figure 6 In one embodiment, an adhesive (e.g., a pattern represented by thick lines) is applied between two opposing flat or substantially flat outer surfaces of the electrode assembly, and is applied at an angle relative to the winding direction of the electrode assembly. Returning to the example above, Figure 6 In the illustrated embodiment, the adhesive 120 can be considered to be applied in a " / " shape. Similar to the embodiments described above, the adhesive can be applied in dots or linearly.

[0068] See Figure 7 In one embodiment, the adhesive (e.g., a pattern represented by thick lines) is applied in a zigzag pattern to a flat or substantially flat portion of the electrode assembly. For example, depending on the viewing angle, the adhesive may be considered to be applied in a “V” shape, a “W” shape, an “N” shape, an “M” shape, a “Z” shape, and / or the like. Similar to the embodiments described above, the adhesive may be applied in dots or may be applied linearly.

[0069] exist Figure 7 In the embodiments shown, the adhesive is illustrated as being linearly connected, in Figure 8 In the embodiments shown, the adhesive (e.g., a pattern represented by thick lines) is connected in a curved shape (e.g., a curved line). For example, depending on the viewing angle, the adhesive can be perceived as being applied in an "S" shape. Similar to the embodiments described above, the adhesive can be applied in the form of dots, or it can be applied linearly.

[0070] In one embodiment, such as Figure 9 In the embodiments shown, the adhesive may be applied as a whole to a suitable area (e.g., a predetermined area or a specific area). In the figures, the adhesive is illustrated as being applied within a flat or substantially flat portion of the electrode assembly, but in another embodiment, the adhesive may be applied to a flat or substantially flat portion of the electrode assembly and toward a first curved portion and / or a second curved portion.

[0071] In addition to the above, see also Figures 5 to 9 Features other than the form of adhesive application in the described embodiments may be found in the above-mentioned examples. Figures 1 to 3 The described embodiments are characterized by the same or substantially the same features; therefore, their redundant descriptions will not be repeated. See above. Figures 5 to 9 This section primarily describes some of the differences between them; other differences, if any, are within the scope of modifications that would naturally be expected by a person skilled in the art to address the corresponding differences.

[0072] As described above, in one or more embodiments of this disclosure, by applying an adhesive to the upper and / or lower surfaces of the electrode assembly to secure the separator, electrical short circuits between the negative and positive electrode plates due to deformation (e.g., curling) or damage to the separator caused by external impact can be prevented or substantially prevented, thereby providing a secondary battery with improved safety.

[0073] Although some embodiments have been described, those skilled in the art will readily understand that various modifications can be made to the embodiments without departing from the spirit and scope of this disclosure. It will be understood that the description of features or aspects within each embodiment should generally be considered applicable to other similar features or aspects in other embodiments, unless otherwise stated. Therefore, as will be apparent to those skilled in the art, the features, characteristics, and / or elements described with respect to a particular embodiment may be used alone or in combination with features, characteristics, and / or elements described with respect to other embodiments, unless specifically indicated otherwise. Therefore, it will be understood that the foregoing is illustrative of various exemplary embodiments and should not be construed as limiting to the specific embodiments disclosed herein, and various modifications to the disclosed embodiments and other exemplary embodiments are intended to be included within the spirit and scope of this disclosure as defined by the appended claims and their equivalents.

Claims

1. A secondary battery, comprising: Electrode assembly, wound around an axis and comprising: Negative electrode plate; Positive electrode plate; and A diaphragm is located between the negative electrode plate and the positive electrode plate; An adhesive is applied to the surface of the electrode assembly perpendicular to the axis to secure the diaphragm. Housing that houses the electrode assembly; The negative electrode lead extends from the negative electrode plate; and A positive electrode lead is drawn out from the positive electrode plate; The diaphragm includes multiple diaphragms. The adhesive covers at least two of the plurality of diaphragms, and The at least two diaphragms have ends that are joined together on the surface of the electrode assembly perpendicular to the axis, and the adhesive is applied to the edges of the ends.

2. The secondary battery according to claim 1, The electrode assembly is stacked in the following order: the negative electrode plate, one of the plurality of diaphragms, the positive electrode plate, and another of the plurality of diaphragms. The adhesive covers at least two adjacent septa of the plurality of septa.

3. The secondary battery of claim 2, wherein the at least two adjacent separators have ends that are aggregated together, and the adhesive is applied to the edges of the ends.

4. The secondary battery of claim 1, wherein the electrode assembly is wound into an elongated oval shape as viewed in a plane perpendicular to the axis, having a flat portion defined by two opposing flat outer surfaces, and a curved portion connecting the two opposing flat outer surfaces to each other from one side and the opposite side, respectively. The adhesive is located on the flat portion.

5. The secondary battery according to claim 4, wherein the adhesive is spaced apart from the curved portion.

6. The secondary battery of claim 1, wherein the adhesive is located on the outer portion of the electrode assembly away from the center of the electrode assembly.

7. The secondary battery of claim 6, wherein the adhesive is spaced apart from the edge of the electrode assembly.

8. The secondary battery of claim 4, wherein the adhesive is applied along the winding direction of the electrode assembly.

9. The secondary battery of claim 1, wherein the adhesive is applied in the form of dots.

10. The secondary battery according to claim 1, wherein the adhesive is divided into multiple segments.

11. The secondary battery of claim 8, wherein the adhesive is located in multiple rows.

12. The secondary battery according to claim 1, wherein the binder comprises a fluorescent material.

13. The secondary battery of claim 4, wherein the adhesive is applied across the winding direction of the electrode assembly.

14. The secondary battery of claim 1, wherein the adhesive is applied linearly.

15. The secondary battery of claim 1, wherein the adhesive integrally covers the region of the electrode assembly perpendicular to the axis.

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