KR20070096649A - Electrode assembly for lithium rechargeable battery and lithium rechargeable battery using the same - Google Patents

Abstract

An electrode assembly for a lithium secondary battery and a lithium secondary battery containing the electrode assembly are provided to prevent the welding part of an electrode tap from being separated by the rotation or flow of an electrode assembly. An electrode assembly(210) comprises a positive electrode plate(212) and a negative electrode plate(214) facing each other; a separator(213) interposed between the positive electrode plate and the negative electrode plate; and a sealing tape(220) adhered to the outer circumference of the jelly-roll type electrode assembly, wherein the sealing tape is provided with a base and an adhesive layer coated on the inner circumference of the base, and the adhesive layer is made of a material absorbing an electrolyte solution so as to be swollen and has a thickness thicker than the base.

Description

Electrode assembly for lithium secondary battery and lithium secondary battery using same {Electrode assembly for lithium rechargeable battery and Lithium rechargeable battery using the same}

1 is an exploded perspective view of a typical cylindrical lithium secondary battery

Figure 2a is a perspective view of an electrode assembly for a lithium secondary battery according to an embodiment of the present invention

FIG. 2B is a cross-sectional view taken along the line A-A of FIG. 2A

Figure 3 is a graph showing the experimental results according to an embodiment of the present invention

<Description of Symbols for Main Parts of Drawings>

210-Electrode Assembly 212-Bipolar Plate

213-Separator 214-Cathode Plate

216-Positive Tab 218-Negative Tab

220-sealing tape 221-base material

222-adhesive layer

The present invention relates to an electrode assembly for a lithium secondary battery and a lithium secondary battery using the same, and more particularly, to a sealing tape attached to an outer circumferential surface of an electrode assembly to prevent loosening of a wound electrode assembly, an electrolyte solution. By coating an adhesive layer made of a material that absorbs the electrolyte and is swelled to the substrate, and when the electrolyte is impregnated, the adhesive layer swells to bring the electrode assembly into close contact with the can, thereby rotating or flowing the electrode assembly. The present invention relates to an electrode assembly for a lithium secondary battery capable of preventing disconnection of a welding part and a lithium secondary battery using the same.

In general, as the light weight and high functionality of portable wireless devices such as a video camera, a portable telephone, a portable computer, and the like progress, a lot of researches have been conducted on secondary batteries used as driving power. Such secondary batteries include, for example, nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, and lithium secondary batteries. Among them, lithium secondary batteries are rechargeable, compact, and large-capacity, and are widely used in advanced electronic devices because of their high operating voltage and high energy density per unit weight.

1 is an exploded perspective view of a general cylindrical lithium secondary battery. Hereinafter, for convenience, a cylindrical lithium secondary battery will be described as an example.

1, the cylindrical lithium secondary battery 100 is assembled to an electrode assembly 110, a cylindrical can 130 containing the electrode assembly 110 and an electrolyte, and an upper portion of the cylindrical can 130. It is formed to include a cap assembly 150 for sealing the cylindrical can 130 and for flowing the current generated in the electrode assembly 110 to an external device.

The electrode assembly 110 includes a positive electrode plate 112 coated with a positive electrode active material layer on a surface of a positive electrode current collector, a negative electrode plate 114 coated with a negative electrode active material layer on a surface of a negative electrode current collector, and the positive electrode plate 112 and a negative electrode plate 114. The separator 113 is disposed between the cathode plate 112 and the cathode plate 114 to electrically insulate the jelly plate into a jelly-roll shape. Although not shown in detail in the drawing, the positive electrode plate 112 includes a positive electrode current collector made of a thin metal plate having excellent conductivity, for example, aluminum (Al) foil, and a positive electrode active material layer coated on both surfaces thereof. have. At both ends of the positive electrode plate 112, a positive electrode current collector region in which a positive electrode active material layer is not formed, that is, a positive electrode non-coating portion is formed. One end of the positive electrode non-coating portion is generally formed of aluminum (Al), and the positive electrode tab 116 protruding a predetermined length to the upper portion of the electrode assembly 110 is bonded. In addition, the negative electrode plate 114 includes a negative electrode current collector made of a conductive metal thin plate, for example, copper (Cu) or nickel (Ni) foil, and a negative electrode active material layer coated on both surfaces thereof. Both ends of the negative electrode plate 114 are provided with a negative electrode current collector region, that is, a negative electrode non-coating portion, in which a negative electrode active material layer is not formed. One end of the negative electrode non-coating portion is generally formed of nickel (Ni) material, and the negative electrode tab 118 protruding a predetermined length to the lower portion of the electrode assembly 110 is bonded. In addition, the upper and lower portions of the electrode assembly 110 may further include an insulating plate (not shown) to prevent contact with the cap assembly 150 or the cylindrical can 130, respectively. A sealing tape 120 is wound around the outer circumferential surface of the electrode assembly 110 to support, protect, and insulate the shape of the electrode assembly 110. The sealing tape 120 is typically made of a polyolefin-based material such as polyethylene (PE), polypropylene (PP), or polyimide (PI).

The cylindrical can 130 has a cylindrical side plate 132 having a predetermined diameter and a lower plate sealing the lower portion of the cylindrical side plate 132 so that a predetermined space in which the cylindrical electrode assembly 110 can be accommodated is formed. 134 is formed, and an upper portion of the cylindrical side plate 132 is opened to insert the electrode assembly 110. As the negative electrode tab 118 of the electrode assembly 110 is bonded to the center of the bottom plate 134 of the cylindrical can 130, the cylindrical can 130 itself serves as a negative electrode. In addition, the cylindrical can 130 is generally formed of nickel (Ni), iron (Fe) or an alloy thereof. In addition, the cylindrical can 130 is formed with a clipping portion 138 (before the bending) is bent from the top to the inside to press the upper portion of the cap assembly 150 coupled to the upper opening. In addition, the cylindrical can 130 is recessed inward to press the lower portion of the cap assembly 150 at a position spaced apart from the creeping portion 138 by a distance corresponding to the thickness of the cap assembly 150. A beading portion 136 is further formed.

The cap assembly 150 includes a safety vent 152, a current blocking means 154, a secondary protection element 156, and a cap up 158. The safety vent 152 has a plate-like protrusion formed at the center at the bottom thereof, and is positioned below the cap assembly 150, and the protrusion is deformed upward by the pressure generated inside the secondary battery. The positive electrode tab 116 of the positive electrode plate 112 and the negative electrode plate 114 of the electrode assembly 110, for example, the positive electrode plate 112, is welded to a predetermined surface of the lower surface of the safety vent 152. The safety vane 152 and the positive electrode plate 116 of the electrode assembly 110 are electrically connected. Here, the remaining electrode plate, for example, the cathode, of the positive electrode plate 112 and the negative electrode plate 114 is electrically connected to the can 130 by a tab or direct contact method (not shown). The safety vent 152 is deformed or ruptured when the pressure inside the can 130 rises, which serves to damage the current interruption means 154. In addition, an upper portion of the safety van 152 is further provided with a current blocking means 154 that is damaged when the safety van 152 is deformed when the current is blocked, the upper portion of the current blocking means 154 The secondary protection element 156 is located to block the current. In addition, an upper portion of the secondary protection device 156 is further provided with a conductive cap up 158 that provides a positive voltage or a negative voltage to the outside.

When the cylindrical lithium secondary battery is subjected to an external shock such as a drop, the electrode assembly is likely to flow or rotate inside the can. When the electrode assembly flows in the can or rotates to a certain degree, the electrode tab attached to the electrode assembly moves or rotates accordingly. In this case, there is a problem that the welding portion between the positive electrode tab and the safety vant and the welding portion between the negative electrode tab and the can may be broken, thereby causing the internal circuit of the battery to be disconnected. In the case of the square lithium secondary battery, the electrode assembly is less likely to rotate than the cylindrical shape, but the internal circuit of the battery may be disconnected because the electrode assembly flows inside the can and the welding part of the electrode tab is broken.

The present invention has been made to solve the above problems, and in particular, in a sealing tape attached to the outer circumferential surface of the electrode assembly to prevent loosening of the wound electrode assembly, the swell by absorbing the electrolyte and absorbing the electrolyte solution. By coating an adhesive layer of a swelling material on a substrate, when the electrolyte solution is impregnated, the adhesive layer swells to bring the electrode assembly into close contact with the can, thereby causing the welding part of the electrode tab to disconnect due to rotation or flow of the electrode assembly. An object of the present invention is to provide an electrode assembly for a lithium secondary battery that can be prevented and a lithium secondary battery using the same.

In order to solve the above problems, the electrode assembly for a lithium secondary battery of the present invention comprises a separator interposed between the positive electrode plate and the negative electrode plate, the positive electrode plate and the negative electrode plate facing each other, the positive electrode plate and the negative electrode plate and the separator in a jelly roll shape In an electrode assembly for a lithium secondary battery comprising a sealing tape attached to the wound outer peripheral surface, the sealing tape comprises a base material and an adhesive layer coated on the inner peripheral surface of the base material, the adhesive layer absorbs the electrolyte solution and swelling ( Swelling) is made of a material, characterized in that formed thicker than the thickness of the substrate.

In addition, the sealing tape may be attached to surround the outer circumferential surface, including a finish portion at which the outermost end of the separator is located among the outer circumferential surfaces of the electrode assembly. In addition, the sealing tape may be attached to the upper end and the lower end of the outer peripheral surface so that the separator is exposed as it is.

In addition, the substrate may be made of any one of polyethylene (PE), polypropylene (PP), and polyimide (PI). In addition, the adhesive layer is preferably made of polyacrylate (poly acrylate). In addition, the adhesive layer may be made of any one of poly methyl methacrylate (PMMA), poly ethyl methacrylate (PEMA), and poly butyl methacrylate (PBMA).

In addition, the adhesive layer is preferably formed at least twice as thick as the base material.

In addition, the lithium secondary battery of the present invention is an electrode assembly having a positive electrode plate and a negative electrode plate facing each other, a separator interposed between the positive electrode plate and the negative electrode plate, the positive electrode plate and the negative electrode plate, and a sealing tape attached to the outer peripheral surface wound in a jelly roll shape In the lithium secondary battery comprising a can assembly for accommodating the electrode assembly, the cap assembly for sealing the top opening of the can, wherein the sealing tape has a substrate and an adhesive layer coated on the inner peripheral surface of the substrate, the adhesive The layer is made of a material that absorbs the electrolyte and is swelled, and is formed to be thicker than the thickness of the substrate.

In addition, the sealing tape may be formed in any one of the shapes described above. In addition, the entire sealing tape or the coating layer may be formed of any one of the materials described above.

In addition, the adhesive layer is preferably formed at least twice as thick as the base material.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following drawings, only the case of a cylindrical lithium secondary battery electrode assembly is shown, but in the case of an electrode assembly for a rectangular lithium secondary battery, the present invention can be applied as well.

2A is a perspective view of an electrode assembly for a lithium secondary battery according to an exemplary embodiment of the present invention, and FIG. 2B is a sectional view taken along the line A-A of FIG. 2A. In the following description, the horizontal standard of the sealing tape 220 before attaching to the outer circumferential surface of the electrode assembly 210 is referred to as length, and the vertical standard is referred to as width for convenience.

2A and 2B, an electrode assembly 210 for a lithium secondary battery according to an exemplary embodiment of the present invention includes a positive electrode plate 212, a negative electrode plate 214, and a separator 213. In addition, the electrode assembly 210 includes a positive electrode tab 216, a negative electrode tab 218, and a sealing tape 220.

The positive electrode plate 212 includes a positive electrode current collector, a positive electrode active material layer, and a positive electrode non-coating portion. The positive electrode current collector is formed of a conductive metal material to collect electrons from the positive electrode active material layer and move them to an external circuit. The cathode active material layer is prepared by mixing a cathode active material, a conductive material and a binder, and is formed by coating a predetermined thickness on the cathode current collector. The positive electrode non-coating portion is a portion in which a positive electrode active material layer is not formed in the positive electrode current collector. The positive electrode tab 216 is welded to one side of the positive electrode non-coating portion.

The negative electrode plate 214 includes a negative electrode current collector, a negative electrode active material layer, and a negative electrode non-coating portion. The negative electrode current collector is formed of a conductive metal material to collect electrons from the negative electrode active material layer and move them to an external circuit. The negative electrode active material layer is prepared by mixing a negative electrode active material, a conductive material and a binder, and is formed by coating a predetermined thickness on the negative electrode current collector. The negative electrode non-coating portion is a portion in which a negative electrode active material layer is not formed in the negative electrode current collector, and the negative electrode tab 218 is welded to one side of the negative electrode non-coating portion.

The positive electrode tab 216 and the negative electrode tab 218 are respectively welded to the positive and negative electrode portions to serve to electrically connect the electrode assembly 210 and other parts of the battery. The positive electrode tab 216 and the negative electrode tab 218 are welded by resistance welding, and a lamination tape may be attached to the welding portion to prevent short and heat generation. Here, the welding method of the positive electrode tab 216 and the negative electrode tab 218 is not limited.

The sealing tape 220 includes a substrate 221 and an adhesive layer 222. In this case, the sealing tape 220 is attached to the outer circumferential surface of the positive electrode plate 212, the negative electrode plate 214, and the separator 213 wound in a jelly roll shape. More specifically, the sealing tape 220 is attached to surround the outer circumferential surface including a finish portion 213a at which the outermost end of the separator 213 is located among the outer circumferential surfaces of the electrode assembly 210. Since the sealing tape 220 should be prevented from loosening the electrode assembly 210, it must be attached to the finish portion 213a. In addition, the sealing tape 220 is positioned between the outer circumferential surface of the electrode assembly 210 and the inner surface of the can. The sealing tape 220 may be attached to a portion of the outer circumferential surface of the electrode assembly 210 except for the upper end and the lower end as shown in FIG. 2A. The upper end portion is a portion that acts as a space through which the electrolyte solution can penetrate between the can and the electrode assembly 210, and the lower end portion is a portion where the electrolyte injected into the bottom of the can comes into contact with the electrode assembly 210. Therefore, it is preferable that the sealing tape 220 is not attached to the upper end and the lower end in view of the impregnation of the electrolyte. When the sealing tape 220 is attached to a portion other than the upper end and the lower end of the outer circumferential surface of the electrode assembly 210, the separator 213 surrounding the outer circumferential surface is exposed as it is. In addition, although not shown in the drawing, the sealing tape 220 may be attached to surround the entire outer circumferential surface of the electrode assembly 210.

The substrate 221 supports the adhesive layer 22 at the outer side of the adhesive layer 222. At this time, the substrate 221 is made of a polyolefin-based material such as polyethylene (PE), polypropylene (PP), polyimide (PI). The polyethylene and the like have a large surface energy difference from the non-aqueous electrolyte, so that the electrolyte molecules are not easily bonded to a surface made of polyethylene or the like. Therefore, the polyethylene or the like is difficult to swell since the electrolyte is buried in an approximately spherical shape due to surface tension and is not intimate with the electrolyte. In addition, the substrate 221 is formed to a thickness of approximately 10 to 20㎛. However, the thickness of the substrate 221 is not limited thereto, but may vary depending on the size of the battery.

One surface of the adhesive layer 222 is coated on the inner surface of the substrate 221, and the other surface is attached to the outer circumferential surface of the electrode assembly 210. The adhesive layer 222 may be coated on the entire inner surface of the substrate 221, and may be coated on a portion of the inner surface of the substrate 221. When the adhesive layer 222 is formed on a part of the inner surface of the substrate 221, the adhesive layer 222 must be formed at a portion facing the finish portion 213a of the electrode assembly 210. In addition, when the adhesive layer 222 is formed on a portion of the inner surface of the substrate 221, the adhesive layer 222 may be formed in a stripe shape, and the shape of the adhesive layer 222 is not limited thereto.

The adhesive layer 222 is made of a polymer material that absorbs electrolyte and is swelled. Some of the high molecular materials have a property of absorbing a solvent and swelling. Swelling is a property of polymer materials, in which solvent molecules penetrate between chains of polymer materials, thereby increasing their volume. The polymer material has a crystal part and an amorphous part, and the solvent mainly penetrates into the amorphous part having a large space to penetrate. Swelling may also occur in the crystalline portion after a long time, but the swelling is less likely to occur than the amorphous portion due to the narrow spacing between the polymer chains. As the polymer material, an adhesive component such as poly acrylate may be used. Polyacrylates include poly methyl methacrylate (PMMA), poly ethyl methacrylate (PEMA), poly butyl methacrylate (PBMA), and the like. The polyacrylate, particularly PMMA, is dissolved when it comes in contact with the electrolyte, and in order to allow the polyacrylate to be swelled without being dissolved, the polyacrylate is cross-linked. When the adhesive layer 222 is made of an adhesive component, only the thickness of the coating layer may be adjusted to prepare a tape in which adhesive components of various thicknesses exist, so that the swelling is easily performed according to the gap between the electrode assembly 210 and the can. You can adjust the degree. The adhesive layer 222 may be formed to a thickness of 15 to 200㎛. However, the thickness of the adhesive layer 222 is not limited thereto, but may be formed in various thicknesses according to the specification of the battery.

The sealing tape 220 is formed with a pressure-sensitive adhesive layer 222 coated with a material that is easy to swell on the surface of the substrate 221, and is formed to a larger thickness than the thickness of the substrate 221, thereby absorbing electrolyte molecules Swelling prevents the electrode assembly 210 from flowing or rotating inside the can.

The degree of swelling of the substrate 221 and the adhesive layer 222 of the sealing tape 220 was measured by experiment. The results of this experiment are shown in [Table 1]. In addition, the data of [Table 1] is shown in the graph of FIG. In Figure 3, the battery specification number (Battery Spec. #) On the horizontal axis represents Experiment Nos. 1 to 8 in Table 1, and the diameter Φ on the vertical axis represents the outer diameter of the electrode assembly and the inner diameter of the can. In addition, J / R O.D. in the rectangular box represents the outer diameter of the electrode assembly in the form of jelly roll, and Can I.D. represents the inner diameter of the can.

TABLE 1

Experiment number Outer diameter of electrode assembly (mm) Inner diameter of can (mm) One 17.05 17.45 2 17.1 17.45 3 17.125 17.45 4 17.125 17.45 5 17.25 17.55 6 17.275 17.55 7 17.35 17.65 8 16.85 17.45

As shown in [Table 1], the difference between the outer diameter of the electrode assembly and the inner diameter of the can is so large that even if the negative electrode plate is expanded by repetition of charging and discharging, the clearance between the outer peripheral surface of the electrode assembly and the inner peripheral surface of the can is larger than the expansion amount. .

In the battery Nos. 1 to 8, polypropylene substrates were formed to a thickness of 10 μm, and a polyacrylate-based adhesive layer was formed to a thickness of 15 μm. In this case, after the electrolyte assembly was sufficiently moistened in the electrode assembly, the lithium secondary battery with repeated charge and discharge was disassembled and the thickness of the adhesive layer was measured. As a result, the result was expanded to approximately 1.5 to 2 times. In addition, when the external shock was applied to the lithium secondary battery thus formed and the possibility of disconnection due to rotation or flow of the electrode assembly was measured, the possibility of disconnection was significantly low in the battery specifications of 1 to 7, which showed excellent safety.

However, in the battery standard of the experiment No. 8, since the outer diameter of the electrode assembly is made smaller and the amount of expansion of the negative electrode plate is relatively small, the electrode assembly is shaken in the can, and in some cases, the disconnection occurs when the electrode assembly is severe.

Meanwhile, in the battery standard of Experiment No. 8, a polypropylene base material was formed to a thickness of 20 μm, and a polyacrylate-based adhesive layer was formed to a thickness of 100 μm. In this case, after the electrolyte assembly was sufficiently moistened in the electrode assembly, the lithium secondary battery with repeated charge and discharge was disassembled and the thickness of the adhesive layer was measured. As a result, the result was expanded about 2 times. In addition, when the external shock was applied to the lithium secondary battery thus formed, and the possibility of disconnection due to the rotation or flow of the electrode assembly was measured, the electrode assembly was fixed with little shaking and the possibility of disconnection was also significantly low.

Therefore, when the gap between the electrode assembly and the can is large in a high power battery, the flow of the electrode assembly may be prevented by adjusting the thickness of the adhesive layer of the sealing tape without having to readjust the size of the can. At this time, the thickness of the pressure-sensitive adhesive layer is preferably larger than the thickness of the base material, preferably at least two times thicker. However, the thickness ratio of the adhesive layer and the substrate is not limited thereto.

Electrode assembly for a lithium secondary battery according to an embodiment of the present invention can be applied to the lithium secondary battery shown in FIG. In addition, the electrode assembly for a lithium secondary battery according to an embodiment of the present invention may be applied to a rectangular lithium secondary battery although not shown in the drawing. Therefore, the configuration of the lithium secondary battery to which the lithium secondary battery electrode assembly is applied is not limited thereto, and the lithium secondary battery electrode assembly may be applied to the lithium secondary battery having various configurations.

Next, the operation of the lithium secondary battery to which the electrode assembly according to the embodiment of the present invention is applied will be described. In the following description, a case where the electrode assembly for a lithium secondary battery according to the embodiment of FIG. 2A is applied will be described.

Referring to FIG. 2A, the electrode assembly 210 has a sealing tape 220 attached to an outer circumferential surface of a jelly roll in which a positive electrode plate 212, a separator 213, and a negative electrode plate 214 are stacked and wound. The sealing tape 220 is formed by coating an adhesive layer 222 of a polyacrylic material that is absorbed by an electrolyte solution on an inner circumferential surface of the substrate 221 of a polyolefinic material. The polymer material, such as polyacryl, is composed of a crystalline portion formed to have regularity by repeating the structure of a monomer (monomer) and an amorphous portion formed by randomly arranged molecules without regularity. When the electrolyte is injected into the can and the electrolyte molecules wet the adhesive layer 222, the electrolyte molecules first penetrate into the amorphous portion to open the polymer chain, and after a long time, the electrolyte molecules penetrate the crystal portion in a predetermined amount. The volume of 222 is increased. When the volume of the adhesive layer 222 increases, the outer circumferential surface of the electrode assembly 210 and the inside of the can are in close contact with each other to prevent the electrode assembly 210 from flowing or rotating inside the can even when an external shock such as a drop of the battery is applied. . In addition, the sealing tape 220 also serves to support and protect the electrode assembly 210, which is an inherent purpose of the sealing tape, from being released.

As described above, the present invention is not limited to the specific preferred embodiments described above, and any person having ordinary skill in the art to which the present invention pertains without departing from the gist of the present invention claimed in the claims. Various modifications are possible, of course, and such changes are within the scope of the claims.

According to the electrode assembly for a lithium secondary battery according to the present invention, when the gap between the electrode assembly and the can is large, such as a high power battery, by adjusting the thickness of the adhesive layer without manufacturing the can in a separate standard, the electrode assembly Is in close contact with the can to prevent the phenomenon that the welding portion of the electrode tab is disconnected by the rotation or flow of the electrode assembly.

Claims (11)

In an electrode assembly for a lithium secondary battery comprising a positive electrode plate and a negative electrode plate facing each other, a separator interposed between the positive electrode plate and the negative electrode plate, the positive electrode plate, the negative electrode plate and the separator is attached to the outer peripheral surface wound in a jelly roll shape, The sealing tape has a substrate and an adhesive layer coated on the inner peripheral surface of the substrate, The adhesive layer is made of a material that absorbs the electrolyte solution and swelled (swelling), the electrode assembly for a lithium secondary battery, characterized in that formed thicker than the thickness of the substrate. The method of claim 1, The sealing tape is an electrode assembly for a lithium secondary battery, characterized in that attached to surround the outer circumferential surface including a finish portion is located at the outermost end of the separator of the outer circumferential surface of the electrode assembly. The method according to claim 1 or 2, The sealing tape is a lithium secondary battery electrode assembly, characterized in that the upper end and the lower end of the outer peripheral surface is attached so that the separator is exposed as it is. The method of claim 1, The substrate is a lithium secondary battery electrode assembly, characterized in that made of any one of polyethylene (PE), polypropylene (PP), polyimide (PI). The method of claim 1, The adhesive layer is a lithium secondary battery electrode assembly, characterized in that made of polyacrylate (poly acrylate). The method of claim 5, The adhesive layer is a lithium secondary battery electrode assembly, characterized in that made of any one of PMMA (poly methyl methacrylate), PEMA (poly ethyl methacrylate), PBMA (poly butyl methacrylate). The method of claim 1, The adhesive layer is a lithium secondary battery electrode assembly, characterized in that formed at least twice as thick as the base material. An electrode assembly having a positive electrode plate and a negative electrode plate facing each other, a separator interposed between the positive electrode plate and the negative electrode plate, a positive electrode plate and a negative electrode plate, and a sealing tape attached to an outer circumferential surface of which the separator is wound in a jelly roll shape, a can housing the electrode assembly; In the lithium secondary battery comprising a cap assembly for sealing the top opening of the can, The sealing tape has a substrate and an adhesive layer coated on the inner peripheral surface of the substrate, The adhesive layer is made of a material that absorbs the electrolyte and is swelled (swelling), the lithium secondary battery characterized in that it is formed thicker than the thickness of the substrate. The method of claim 8, The sealing tape is a lithium secondary battery, characterized in that the shape according to claim 2 or 3. The method of claim 8, The sealing tape is a lithium secondary battery, characterized in that made of a material according to any one of claims 4 to 6. The method of claim 8, The adhesive layer is a lithium secondary battery, characterized in that formed at least twice as thick as the base material.

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