CN116941079A

CN116941079A - Wound electrode assembly and secondary battery including the same

Info

Publication number: CN116941079A
Application number: CN202280014849.7A
Authority: CN
Inventors: 朴仁福
Original assignee: LG Energy Solution Ltd
Current assignee: LG Energy Solution Ltd
Priority date: 2021-11-24
Filing date: 2022-11-24
Publication date: 2023-10-24

Abstract

According to an embodiment of the present disclosure, there is provided a winding type electrode assembly in which a positive electrode sheet, a negative electrode sheet, and a separator interposed between the positive electrode sheet and the negative electrode sheet are wound together, wherein an outermost side of the winding type electrode assembly is wound with a non-coated portion on the negative electrode sheet where an active material layer is not formed, wherein in the non-coated portion of the negative electrode sheet, a swelling tape is attached toward an inner surface of a central portion of the winding type electrode assembly, and wherein one or more protrusions or wrinkles are formed on the swelling tape.

Description

Wound electrode assembly and secondary battery including the same

Technical Field

Cross Reference to Related Applications

The present application claims the benefits of korean patent application No.10-2021-0163387 filed on the korean intellectual property office at 24 months of 2021 and korean patent application No.10-2022-0158763 filed on the korean intellectual property office at 23 months of 2022, the entire contents of both korean patent applications being incorporated herein by reference.

The present disclosure relates to a wound electrode assembly and a secondary battery including the same.

Background

As technology advances and demand for mobile devices increases, demand for secondary batteries as energy sources increases rapidly. In particular, secondary batteries have attracted considerable attention as energy sources for power-driven devices such as electric bicycles, electric vehicles, and hybrid electric vehicles, and as energy sources for mobile devices such as mobile phones, digital cameras, laptop computers, and wearable devices.

Based on the shape of the battery case, the secondary battery is classified into a cylindrical battery in which an electrode assembly is mounted in a cylindrical metal can, a prismatic battery in which an electrode assembly is mounted in a prismatic metal can, and a pouch-type battery in which an electrode assembly is mounted in a pouch-type case made of an aluminum laminate sheet. Among these batteries, the cylindrical battery has advantages in that it has a relatively large capacity and is structurally stable.

The electrode assembly mounted in the battery case is a power generation device that can be charged and discharged, and has a laminate structure of a positive electrode-separator-negative electrode. The electrode assembly is classified into a winding type, a stacking type, and a stacking/folding type. The winding type is a shape in which a positive electrode and a negative electrode each made of a long sheet coated with an active material are wound together with a separator interposed therebetween, the stacking type is a shape in which a plurality of positive electrodes and a plurality of negative electrodes each having a predetermined size are sequentially stacked in a state in which the separator is interposed therebetween, and the stacking/folding type is a combination of the winding type and the stacking type. Among these types, the rolled electrode assembly has advantages of easy manufacture and high energy density per unit weight.

Therefore, in recent years, with an increase in demand for a battery realizing high capacity and high output, in the case of a cylindrical battery, optimization is being performed by changing the thickness of a current collector or separator and the size or shape of a can, a top cover, or the like, so as to place a large number of electrodes in a limited space.

As one of the methods thereof, a method of using copper as an external tab as a negative electrode current collector has been proposed. That is, the tab and separator located on the outside are removed, and the copper current collector physically abuts on the cylinder, so that the current flows out.

By this method, the input amount of the partitioning member and the input amount of the tab can be reduced, and the outer diameter can be slightly reduced, so that the effects of securing a space and reducing costs can be achieved, and the secured space can be utilized to increase the capacity or to increase the output. In addition, since the copper current collector is directly abutted on the can, a heat transfer area is increased, and thus the heat generation level can be improved.

However, when copper is actually exposed on the housing portion, depending on the number of windings, one or two points with a larger outer diameter will abut on the can, which will be less effective than previously expected.

To improve this, the contact level is increased by using a swelling tape having a property of swelling when reacting with an electrolyte, but when attaching during manufacturing, a gas trap is generated, which causes a problem of an increase in outer diameter and thus a decrease in productivity.

Therefore, there is a need to develop a winding type electrode assembly and a secondary battery technology that can solve these problems.

Disclosure of Invention

Technical problem

An object of the present disclosure is to provide a winding-type electrode assembly that can uniformly control a gas trap generated by attachment of a swelling tape, thereby improving a contact level of an outermost negative electrode non-coating portion with a battery case while solving the problem of an increase in outer diameter due to the gas trap, and a secondary battery including the same.

The objects of the present disclosure are not limited to the above objects, and other objects not mentioned herein should be clearly understood by those skilled in the art from the following detailed description and the accompanying drawings.

Technical solution

According to one embodiment of the present disclosure, there is provided a wound electrode assembly in which a positive electrode sheet, a negative electrode sheet, and a separator interposed between the positive electrode sheet and the negative electrode sheet are wound together,

wherein the outermost side of the wound electrode assembly is wound with a non-coating portion on the negative electrode sheet, on which an active material layer is not formed,

wherein, in the non-coating portion of the negative electrode sheet, a swelling tape is attached toward the inner surface of the central portion of the rolled electrode assembly, and

wherein one or more protrusions or corrugations are formed on the swelling belt.

The swelling tape may be attached to a portion of an inner surface of the non-coated portion of the negative electrode sheet, and may be attached to a portion of the coated portion of the negative electrode sheet in a direction of the coated portion of the negative electrode sheet at a boundary surface between the non-coated portion and the coated portion of the negative electrode sheet.

Alternatively, the swelling tape may be formed only on a part of the inner surface of the non-coated portion of the negative electrode sheet.

Further, the swelling tape may be formed to cover 10% to 90% of the total area of the non-coated portion of the negative electrode sheet.

Further, the non-coated portion of the outermost negative electrode sheet on which the swelling tape is formed may face the coated portion of the negative electrode sheet located on the inner side.

Meanwhile, the non-coated portion of the negative electrode sheet contacting the swelling belt may be formed with protrusions or wrinkles corresponding to the swelling belt.

The protrusions or wrinkles formed on the non-coated portion of the negative electrode sheet may be formed by the transmission of the protrusions or wrinkles of the swelling tape.

Air may be trapped in the bulges or folds of the swelling belt.

Here, air may be trapped between the swelling tape and the non-coated portion of the negative electrode sheet.

The protrusions may have a regular pattern. Specifically, the roughness Ra of the projections may be 0.1mm to 20mm, and the size of the projections may be 10 μm to 5mm. When the projections are formed of two or more projections, the distance between the two or more projections may be 50 μm to 5mm.

Meanwhile, the wrinkles may be formed to have irregularities.

According to another embodiment of the present disclosure, there is provided a method for manufacturing a rolled electrode assembly, the method including:

electrode assembly manufacturing steps: winding a positive electrode sheet, a negative electrode sheet, and a separator interposed between the positive electrode sheet and the negative electrode sheet, and winding a non-coating portion of the negative electrode sheet, on which an active material layer is not formed, on the outermost side to manufacture a wound electrode assembly; and

a tape attaching step: on the inner surface of the wound electrode assembly facing the center portion of the negative electrode sheet, a swelling tape formed with protrusions is attached to the non-coated portion of the negative electrode sheet, or the swelling tape is attached to form a wrinkle.

At this time, attaching the swelling tape to form the wrinkles may include: when the swelling tape is attached, a portion of the swelling tape is attached in an unattached form, or vibration is applied to the attached portion to generate micro bubbles or micro wrinkles, or a center portion of a suction cup for attaching the swelling tape is brought into a detached state to form a vacuum space, thereby causing bubbles to be generated during attachment.

Alternatively, according to still another embodiment of the present disclosure, there is provided a method for manufacturing a rolled electrode assembly, the method including:

a tape attaching step: attaching the swelling tape formed with the protrusions to the non-coated portion of one end of the negative electrode sheet, or attaching the swelling tape to form a fold; and

electrode assembly manufacturing steps: the positive electrode sheet, the negative electrode sheet, and the separator interposed between the positive electrode sheet and the negative electrode sheet are wound such that the portion to which the swelling tape is attached is positioned on the inner surface toward the central portion of the wound-type electrode assembly at the outermost side of the wound-type electrode assembly, and the non-coated portion of the negative electrode sheet is wound on the outermost side to manufacture the wound-type electrode assembly.

At this time, attaching the swelling tape to form the wrinkles includes: when the swelling tape is attached, a portion of the swelling tape is attached in an unattached form, or vibration is applied to the attached portion to generate micro bubbles or micro wrinkles, or a center portion of a suction cup for attaching the swelling tape is brought into a detached state to form a vacuum space, thereby causing bubbles to be generated during attachment.

On the other hand, according to another embodiment of the present disclosure, there is provided a secondary battery including the winding-type electrode assembly.

Drawings

Fig. 1 is a perspective view of a rolled electrode assembly according to one embodiment of the present disclosure;

fig. 2 is a top view of a negative electrode sheet of a wound electrode assembly according to one embodiment of the present disclosure;

fig. 3 is a cross-sectional view of a wound electrode assembly according to one embodiment of the present disclosure prior to winding;

fig. 4 is a cross-sectional view of a wound electrode assembly according to another embodiment of the present disclosure before winding; and

fig. 5 is a cross-sectional view taken along A-A' of fig. 1.

Detailed Description

Hereinafter, various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the various embodiments. The present disclosure may be modified in various different ways and is not limited to the embodiments set forth herein.

Portions irrelevant to the description will be omitted to clearly describe the present disclosure, and like reference numerals denote like elements throughout the description.

Further, in the drawings, for convenience of description, the size and thickness of each element are arbitrarily illustrated, and the present disclosure is not necessarily limited to those illustrated in the drawings. In the drawings, the thickness of layers, regions, etc. are exaggerated for clarity. In the drawings, the thickness and area of portions are exaggerated for convenience of description.

Furthermore, throughout the description, when a portion is referred to as "comprising" or "including" a certain component, this means that the portion may also include other components without excluding other components, unless otherwise specified.

Further, throughout the description, when referred to as a "plane", it means that the target portion is viewed from the upper side, and when referred to as a "cross section", it means that the target portion is viewed from the side of the vertically cut cross section.

Fig. 1 is a perspective view of a rolled electrode assembly according to one embodiment of the present disclosure.

Referring to fig. 1, a wound electrode assembly 100 according to an embodiment of the present disclosure may have a shape in which a positive electrode sheet, a negative electrode sheet, and a separator interposed between the positive electrode sheet and the negative electrode sheet are wound together.

At this time, a positive electrode tab 113 may be formed on the positive electrode sheet, and the positive electrode tab 113 may then be electrically connected to a cap assembly of a cylindrical battery or the like to form a positive electrode terminal.

Meanwhile, the outermost side of the wound electrode assembly 100 is wound with a non-coating portion 121 on the negative electrode sheet, on which the active material layer is not formed, and the non-coating portion 121 is then in contact with the inner wall surface of the can of the secondary battery. Therefore, the non-coating portion 121 of the negative electrode tab serves as a terminal and may be electrically and directly connected to a can, which is a cylindrical secondary battery case, and thus a separate negative electrode tab may not be required.

In addition, since the wound electrode assembly 100 may not be formed with a separator on the outermost side thereof, an effect of reducing the outer diameter may be achieved, thereby securing the inner space of the battery, increasing the capacity, increasing the energy density, and improving the battery performance and effect.

However, as described above, when the non-coating portion 121 of the negative electrode sheet is actually exposed to the case portion, there is a problem in that one or two points having a larger outer diameter may abut on the can according to the number of windings, which may reduce the effect as compared with the previous expectation. Accordingly, in the present disclosure, in order to improve the problem, a swelling tape having a property of swelling when reacting with an electrolyte is applied.

At this time, the swelling tape has a structure attached to the inner surface of the center portion facing the rolled electrode assembly 100, instead of the outer case of the non-coating portion 121 of the negative electrode sheet of the rolled electrode assembly 100, so that the non-coating portion 121 of the outermost negative electrode sheet may then be contacted with the cylindrical secondary battery case as a whole without affecting the capacity.

Thus, such a swelling belt is not shown in fig. 1.

Meanwhile, in order to specifically describe the swelling tape according to the present disclosure, fig. 2 illustrates a top view of the negative electrode sheet 120 in the wound electrode assembly 100 of fig. 1 before winding, fig. 3 illustrates a cross-sectional view of the wound electrode assembly 100 of fig. 1 before winding, fig. 4 illustrates a cross-sectional view of the wound electrode assembly 100 before winding according to another embodiment, and fig. 5 illustrates a cross-sectional view taken along A-A' of the wound electrode assembly 100 of fig. 1.

First, referring to fig. 2 and 3, the positive electrode sheet 110 includes a coated portion on which a positive electrode active material layer is formed and a non-coated portion on which the positive electrode active material layer is not formed, and has a structure in which the non-coated portion is disposed between the coated portions and the positive electrode tab 113 is attached to the non-coated portion.

In addition, a separator 130 is interposed between the positive electrode sheet 110 and the negative electrode sheet 120.

The positive electrode sheet 120 includes a coated portion 122 in which an active material layer 123 is formed on a negative electrode current collector 124, and a non-coated portion 121 on which the active material layer 123 is not formed, wherein the non-coated portion 121 is located at one side and wound around the outermost side, thereby functioning as a negative electrode terminal.

Meanwhile, the swelling tape 125 is attached to the winding inner surface of the non-coating portion 121.

Here, the swelling tape 125 may be formed to cover an area a' of 10% to 90% of the total area a of the inner surface of the non-coating portion 121 of the negative electrode sheet 120.

Further, the swelling tape 125 may be formed only on a part of the inner surface of the non-coating portion 121 so as not to overlap the coating portion 123 of the negative electrode sheet 120.

Alternatively, referring to fig. 4, the swelling tape 125' may be attached to a portion of the inner surface of the non-coated portion 121' of the negative electrode sheet 120', and may be attached to a portion of the coated portion 122' of the negative electrode sheet 120 in the direction of the coated portion 122' of the negative electrode sheet 120 at the boundary surface between the non-coated portion 121' and the coated portion 122' of the negative electrode sheet. At this time, the swelling tape may be formed within a range of a length l that does not overlap with the active material layer of the opposite positive electrode sheet 110.

In either case, however, the non-coated portion 121 of the outermost negative electrode sheet 120 on which the swelling tape 125 is formed faces the active material layer 123 of the negative electrode sheet 120 located on the inner side, i.e., the coated portion 122.

Therefore, since the swelling tape 125 is formed on a portion in which the active material layer 123 does not face the positive electrode, that is, on a portion that does not contribute to the capacity, no problem of the capacity occurs. Meanwhile, since the swelling tape 125 is formed at the inner side of the current collector 124 of the negative electrode sheet 120 at the outermost side of the rolled electrode assembly 100, the current collector 124 may be in contact with the can of the cylindrical battery case as a whole, and thus, the effects expected in the present disclosure may be achieved without reducing the improvement effects of the conductivity and the heat generation level.

Meanwhile, the swelling tape 125 has a property of expanding its volume when it absorbs an electrolyte, and may be a single-sided tape or a double-sided tape.

At this time, the single-sided tape or the double-sided tape may be made of at least one selected from the group consisting of Polyurethane (PU), polyethylene (PE), polycarbonate (PC), polypropylene (PP), and Polyimide (PI).

Alternatively, the swelling tape 125 may have a structure in which an adhesive layer is formed on one side or both sides of the fabric substrate.

Here, the fabric substrate may be a polyolefin-based substrate, such as a Polyethylene (PE) -based substrate or a polypropylene (PP) -based substrate, and the adhesive layer may contain one or more materials selected from the group consisting of Polyacrylate (PA), rubber, and styrene.

Meanwhile, such a swelling belt 125 may be formed with one or more protrusions or wrinkles 126.

The protrusions or pleats 126 are formed such that the swelling tape 125 can trap air at an appropriate position, and thus, air is trapped in the protrusions or pleats 126 of the swelling tape 125. Specifically, it is formed between the swelling belt 125 and the current collector 124.

Therefore, when the swelling tape 125 is attached by trapping air in the protrusions or folds 126 thereof, protrusions or folds corresponding to the swelling tape 125 may also be formed on the non-coated portion 121 of the negative electrode sheet 120.

That is, referring again to fig. 1, it can be confirmed that the protrusion or fold 126 is transferred to the non-coated portion 121 of the negative electrode sheet.

Accordingly, an air pocket that may occur when the swelling tape 125 is attached to the non-coated portion 121 can be artificially controlled, thereby preventing an abnormal increase in the outer diameter caused thereby. In addition, by creating protrusions or wrinkles on the surface of the non-coating portion 121 of the negative electrode sheet, the non-coating portion 121 may then widen the contact area with the inner surface of the battery case, thereby improving conductivity and improving resistance.

Meanwhile, the protrusion or the corrugation 126 may be artificially formed.

Specifically, the protrusions may be formed by a roll roller or the like having a regular pattern so as to have a regular pattern.

At this time, the average roughness Ra of the center line of the protrusion may be 0.1mm to 20mm, specifically 1mm to 3mm.

The roughness Ra of the bump refers to the height of the bump, and is the height from the flat portion to the highest point of the convex portion.

This allows for height adjustment when producing protrusions on the swelling belt.

If the roughness is too small to be outside the above range, proper air trapping or transfer of an irregular shape to the non-coated portion of the negative electrode sheet may not be sufficiently performed, and if the roughness is too large, the overall volume may increase, which is not preferable.

Further, the dimension W of the protrusions may be 10 μm to 5mm, specifically 100 μm to 2mm.

When the shape of the protrusion is circular, the dimension refers to the diameter, and when the shape is polygonal, the dimension refers to the distance of the longest straight line.

If the size of the protrusions is too small to be outside the above range, the force of pushing outward is insufficient, and thus the surface adhesion effect expected in the present disclosure cannot be sufficiently observed. If the size is too large, the overall volume may increase, which is not preferable.

Further, the protrusions may be formed of two or more protrusions, wherein the distance D between the two or more protrusions may be 50 μm to 5mm, specifically 100 μm to 2mm.

If the distance is too small to be outside the above range, air inside the projections may be bonded together, and the shape may be changed, and thus the resistance distribution may be changed. If the distance is too large, the expected resistance reduction effect may be reduced, which is not preferable.

On the other hand, the swelling tape 125 may be formed with wrinkles having irregularities instead of protrusions having a regular pattern.

Here, the irregularities are not patterns formed in a certain size, height, and distance, but are formed intentionally but without regularity when the swelling tape 125 is attached or manufactured.

However, these wrinkles may also be controlled by artificially providing a space in which air can be trapped, and wrinkles may also be generated in the non-coated portion of the negative electrode sheet by the trapped air. Thus, in this way, the contact area between the non-coating portion of the outermost negative electrode tab and the battery case can be increased.

Next, a method of forming such projections and wrinkles will be described in more detail.

Alternatively, there is provided a method for manufacturing a rolled electrode assembly, the method comprising:

electrode assembly manufacturing steps: the positive electrode sheet, the negative electrode sheet, and the separator interposed between the positive electrode sheet and the negative electrode sheet are wound such that the portion to which the swelling tape is attached is positioned on the inner surface of the wound electrode assembly from the outermost side toward the central portion of the wound electrode assembly, and the non-coated portion of the negative electrode sheet is wound on the outermost side to manufacture the wound electrode assembly.

That is, in other words, the electrode assembly is first manufactured, and then the swelling tape may be attached to the non-coated portion of the negative electrode sheet during winding, or alternatively, the swelling tape is first attached to the non-coated portion of the negative electrode sheet before manufacturing the electrode assembly, and then the negative electrode sheet and other components may be wound to manufacture the electrode assembly.

However, in either case, when the protrusions are formed on the swelling tape, the method is not limited, but for example, the protrusions are formed during the manufacture of the swelling tape using a roller having the protrusions, and the swelling tape, on which the protrusions have been formed, may be attached to the non-coated portion of the negative electrode sheet to manufacture the electrode assembly.

On the other hand, in the case where wrinkles are formed in the swelling tape, they are formed by various methods. Specifically, attaching the swelling tape to form the pleat includes: when the swelling tape is attached, a portion of the swelling tape is attached in an unattached form, or vibration is applied to the attached portion to generate microbubbles or micro-wrinkles, or a center portion of a suction cup for attaching the swelling tape is brought into a detached state to form a vacuum space, thereby causing bubbles to be generated during attachment.

More specifically, when the swelling tape is attached, if a portion of the swelling tape is attached in an unattached form using a roller and then attached to the non-coated portion of the negative electrode sheet, wrinkles are generated in the unattached portion.

Alternatively, when vibration is applied to the attachment portion, the swelling tape is attached in a state in which air is inserted while the attachment portion vibrates, to generate microbubbles and generate micro wrinkles.

Alternatively, when the swelling tape is attached to the non-coated portion of the negative electrode sheet, attachment is performed using a suction cup. At this time, the center portion of the suction cup is brought into a detached state to form a vacuum space, thereby inducing air to form bubbles in the center portion at the time of attachment, so that wrinkles can be formed due to the bubbles.

The protrusions or wrinkles may be formed on the swelling tape by various methods, and the present disclosure is not limited to the above-described methods, which may be formed by simple methods as described above.

On the other hand, according to the present disclosure, the air trap may be controlled by a method such that the contact area between the non-coated portion of the anode and the battery case may be increased by trapped air formed in the swelling tape.

The compositions, structures, etc. of the positive electrode sheet, the negative electrode sheet, and the separator constituting other wound electrode assemblies are known in the art, and thus, detailed descriptions thereof are omitted herein.

Meanwhile, the present disclosure provides a secondary battery including the winding-type electrode assembly.

At this time, the secondary battery may be a cylindrical secondary battery or a prismatic secondary battery in which a wound electrode assembly is mounted in a can.

Such secondary batteries are also known in the art, and thus, a detailed description thereof is omitted herein.

Although the preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, the scope of the present disclosure is not limited thereto, and various modifications and improvements that may be made by those skilled in the art using the basic idea of the present disclosure as defined in the appended claims are also within the scope of the present disclosure.

Description of the reference numerals

100: wound electrode assembly

110: positive plate

120: negative plate

130: partition piece

113: negative electrode tab

121: uncoated portion of negative electrode sheet

122: coating portion of negative electrode sheet

125: swelling belt

126: projections or folds

INDUSTRIAL APPLICABILITY

According to an embodiment, the wound electrode assembly of the present disclosure includes a swelling tape on an inner surface of a battery non-coating portion of an outermost negative electrode sheet, and protrusions or corrugations are intentionally formed on the swelling tape to uniformly control a gas trap, whereby a contact area between the outermost non-coating portion and a subsequent battery case can be increased by using the protrusions or corrugations, thereby achieving the effects of securing conductivity and improving resistance.

Claims

1. A wound electrode assembly in which a positive electrode sheet, a negative electrode sheet, and a separator interposed between the positive electrode sheet and the negative electrode sheet are wound together,

wherein an outermost side of the wound electrode assembly is wound with a non-coating portion on the negative electrode sheet, on which an active material layer is not formed;

wherein, in the non-coating portion of the negative electrode sheet, a swelling tape is attached toward an inner surface of a central portion of the wound electrode assembly, and

2. The rolled electrode assembly of claim 1, wherein:

the swelling tape is attached to a portion of the inner surface of the non-coated portion of the negative electrode sheet, and is attached to a portion of the coated portion of the negative electrode sheet in the direction of the coated portion of the negative electrode sheet at a boundary surface between the non-coated portion and the coated portion of the negative electrode sheet.

3. The rolled electrode assembly of claim 1, wherein:

the swelling band is formed only on a portion of the inner surface of the non-coating portion of the negative electrode sheet.

4. The rolled electrode assembly of claim 1, wherein:

the swelling tape is formed to cover 10% to 90% of the total area of the non-coated portion of the negative electrode sheet.

5. The rolled electrode assembly according to any one of claims 1 to 4, wherein:

the non-coated portion of the outermost negative electrode sheet on which the swelling tape is formed faces the coated portion of the negative electrode sheet located on the inner side.

6. The rolled electrode assembly of claim 1, wherein:

the non-coated portion of the negative electrode sheet contacting the swelling belt is formed with protrusions or wrinkles corresponding to the swelling belt.

7. The rolled electrode assembly of claim 6 wherein:

the protrusions or wrinkles formed on the non-coated portion of the negative electrode sheet are transferred by the protrusions or wrinkles of the swelling tape.

8. The rolled electrode assembly of claim 1, wherein:

air is trapped in the bulges or corrugations of the swelling zone.

9. The rolled electrode assembly of claim 1, wherein:

the protrusions have a regular pattern.

10. The rolled electrode assembly of claim 9, wherein:

the roughness (Ra) of the protrusions is 0.1mm to 20mm.

11. The rolled electrode assembly of claim 9, wherein:

the size of the protrusions is 10 μm to 5mm.

12. The rolled electrode assembly of claim 9, wherein:

the protrusions are formed of two or more protrusions, and a distance between the two or more protrusions is 50 μm to 5mm.

13. The rolled electrode assembly of claim 1, wherein:

the wrinkles are formed to have irregularities.

14. A method for manufacturing a wound electrode assembly according to claim 1, the method comprising:

electrode assembly manufacturing steps: winding a positive electrode sheet, a negative electrode sheet, and a separator interposed between the positive electrode sheet and the negative electrode sheet, and winding a non-coated portion of the negative electrode sheet, on which an active material layer is not formed, on an outermost side to manufacture a wound electrode assembly; and

a tape attaching step: on an inner surface of the wound electrode assembly facing the central portion of the negative electrode sheet, a swelling tape formed with protrusions is attached to the non-coated portion of the negative electrode sheet, or the swelling tape is attached to form wrinkles.

15. The method for manufacturing a rolled electrode assembly according to claim 14, wherein:

attaching the swelling tape to form a pleat includes: a portion of the swelling tape is attached in an unattached form while the swelling tape is attached, or vibration is applied to the attached portion to generate microbubbles or micro-wrinkles, or a center portion of a suction cup for attaching the swelling tape is brought into a detached state to form a vacuum space, thereby causing bubbles to be generated during attachment.

16. A method for manufacturing a wound electrode assembly according to claim 1, the method comprising:

a tape attaching step: attaching a swelling tape formed with protrusions to the non-coated portion of one end portion of the negative electrode sheet, or attaching the swelling tape to form wrinkles; and

electrode assembly manufacturing steps: the positive electrode sheet, the negative electrode sheet, and the separator interposed between the positive electrode sheet and the negative electrode sheet are wound such that the portion to which the swelling tape is attached is positioned on an inner surface toward a central portion of the wound electrode assembly at an outermost side of the wound electrode assembly, and a non-coated portion of the negative electrode sheet is wound on the outermost side to manufacture the wound electrode assembly.

17. The method for manufacturing a rolled electrode assembly according to claim 16, wherein:

18. A secondary battery comprising the wound electrode assembly according to claim 1.