KR20150034965A - Secondary Battery Employed with Seal Tape for Preventing Power Failure of Electrode Assembly - Google Patents

Abstract

In the present invention, provided is a secondary battery, including a jelly-roll type electrode assembly around which a positive electrode and a negative electrode having an active material coating part on at least one surface of current collectors and an inserted separation membrane are wound; a battery case for storing the electrode assembly; an electrolyte which is built in the battery case like the electrode assembly; and a seal tape which enables the wound end part of the electrode assembly to be attached and fixed on the outside surface of the electrode assembly and has a self-cutting part which is cut by expansion stress when the electrode assembly is expanded according to the charging and discharging.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a secondary battery including a seal tape for preventing a short circuit of an electrode assembly,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a secondary battery including a seal tape for preventing a disconnection of an electrode assembly, and more particularly to a secondary battery including a positive electrode and a negative electrode including an active material coating portion on at least one surface of a current collector, A jelly-roll type electrode assembly; A battery case in which the electrode assembly is housed; An electrolyte contained in the battery case together with the electrode assembly; And a seal tape having a winding end portion of the electrode assembly fixedly attached to an outer surface of the electrode assembly and having a self-breaking portion that is broken by an expansion stress upon expansion of the electrode assembly due to charging and discharging, .

As technology development and demand for mobile devices are increasing, the demand for batteries as energy sources is rapidly increasing, and accordingly, a lot of researches on batteries capable of meeting various demands have been conducted.

Typically, in view of the shape of the battery, there is a high demand for a prismatic secondary battery and a pouch-type secondary battery that can be applied to products such as mobile phones with a small thickness. In terms of materials, lithium ion batteries having high energy density, discharge voltage, There is a high demand for a lithium secondary battery such as a lithium ion polymer battery.

Also, the secondary battery is classified according to how the electrode assembly having the anode / separator / cathode structure is formed. Typically, the long battery-shaped anodes and cathodes are jelly- A stacked (stacked) electrode assembly in which a plurality of positive electrodes and negative electrodes cut in units of a predetermined size are sequentially stacked with a separator interposed therebetween, a stacked (stacked) electrode assembly in which a predetermined unit of positive and negative electrodes are stacked, A stack / folding type electrode assembly having a structure in which a bi-cell or a full cell stacked in a single state is wound is exemplified.

Among these, the jelly-roll type electrode assembly has advantages in that it is easy to manufacture and has a high energy density per weight, and thus it has been receiving the spotlight as an electrode assembly of a secondary battery used in mobile devices.

In general, a jelly-roll type electrode assembly is formed by winding a long sheet-like positive electrode and a negative electrode in a densely packed state so as to have a cylindrical or elliptical structure in cross section, and then to easily insert the wound jelly- And attaching a seal tape to the outermost electrode end portion, which is the end of winding, and fixing the seal tape.

However, in the jelly-roll type electrode assembly, the volume of the negative electrode is increased while lithium is deposited on the negative electrode in the charging and discharging process, thereby expanding the entire volume of the jelly-roll type electrode assembly.

Particularly, in the outer portion of the jelly-roll type electrode assembly, the change of the circumference due to the volume increase accumulated from the inside of the electrode assembly is the most severe, while the seal tape attached to the electrode end suppresses the expansion of the electrode assembly, Thereby significantly increasing the stress in the substrate. Accordingly, when the stress is applied to the outer electrode over the limit value, there is a problem that the performance and safety of the battery are seriously threatened because the electrode assembly is short-circuited.

Accordingly, there is a high need for a technique for preventing the short circuit of the electrode assembly due to the expansion stress of the electrode assembly during charging and discharging as well as fixing the shape of the jelly-roll type electrode assembly.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described problems of the prior art and the technical problems required from the past.

The inventors of the present application have conducted intensive research and various experiments and have found that when the winding end of the electrode assembly is fixed with the seal tape having the self-breaking portion formed therein, when the electrode assembly expands due to charging and discharging, The present invention has been accomplished on the basis of the fact that it is possible to prevent short-circuiting of electrodes by effectively eliminating the stress formed on the outer periphery of the electrode assembly.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a rechargeable battery including: a jelly-roll type electrode assembly having a positive electrode and a negative electrode wound with a separator interposed therebetween; A battery case in which the electrode assembly is housed; An electrolyte contained in the battery case together with the electrode assembly; And a seal tape having a winding end portion of the electrode assembly fixedly attached to an outer surface of the electrode assembly and having a self-breaking portion that is broken by an expansion stress when the electrode assembly expands due to charging and discharging.

That is, in the secondary battery according to the present invention, the seal tape on which the self-breaking portion is formed is fixedly attached to the outer surface of the electrode assembly. Therefore, when the electrode assembly is housed in the battery case, When the electrode assembly is expanded due to charge and discharge of the secondary battery, the seal tape is automatically broken, so that expansion of the electrode assembly is not suppressed. As a result, Stress can be relieved.

At this time, it is preferable that the seal tape is made of an electrically insulating polymer resin so as to ensure the electrically insulated state of the outer surface of the electrode assembly. Such a polymer resin may be, for example, at least one selected from the group consisting of polypropylene, polyvinyl chloride, and polyester, but is not limited thereto.

The positive electrode and negative electrode of the electrode assembly according to the present invention may be provided with a positive electrode tab and a negative electrode tab, respectively, on the non-active portion of the current collector, May be attached.

At this time, it is preferable that the seal tape is attached to the remaining surface except the upper surface and / or the lower surface of the electrode assembly protruding the tabs so as not to interfere with the electrical connection between the positive electrode tab and the negative electrode tab.

Specifically, the seal tape may have a structure in which the seal tape is attached while covering the entire side surface excluding the upper surface of the electrode assembly protruded from the electrode tab and the lower surface opposed thereto.

This structure is preferable in terms of securing the insulation of the entire side surface of the electrode assembly and securing the electrode assembly stably.

In addition, the seal tape may be attached to the electrode assembly while covering a part of the side surface of the electrode assembly. More specifically, the seal tape may be formed on the upper surface of the electrode assembly protruded from the electrode tab, , And may be attached while enclosing an area of 5 to 60% based on the total area of the side surface.

Meanwhile, in one specific example, the self-breaking portion formed on the seal tape may be formed to be broken in an expansion range in which the radius of the electrode assembly increases by 3% to 30%.

That is, when the radius of the electrode assembly expands in the range of 3% to 30% or less, the seal tape expands corresponding to the radius of the electrode assembly, and the radius of the electrode assembly expands in the range of 3% to 30% , The seal tape is broken and the expansion of the electrode assembly is not suppressed, thereby preventing an increase in stress.

For this purpose, the self-breaking portion may have a structure in which the thickness of a desired breaking portion is set to be extremely thin to induce tearing of the seal tape, or a structure in which a seal tape is broken when a certain external force is applied, And more specifically, it may be one or more tearing lines formed continuously or discontinuously on the seal tape for more reliable breaking, and more particularly, may be a structure in which the tearing lines are formed in the non- Or more.

In this regard, the detailed structure of the perforations can be of various shapes, such as, but not limited to, diagonal, curved, or straight, as long as the electrode assembly is broken at an expansion range in which the radius of the electrode assembly increases by 3% to 30% And may be formed parallel to the winding end of the electrode assembly so as to be opposed to the expansion direction of the electrode assembly, that is, the winding direction of the electrode assembly.

In this case, the total length of the perforated line should be set within a range in which the seal tape fixes the electrode assembly and can self-break in a desired expansion range of the electrode assembly. More specifically, % ≪ / RTI > to 70%.

If the length of the perforated line is less than 10% based on the length of the seal tape, it is difficult to expect a desired fracture effect due to local breakage in the desired expansion range, and it is more than 70% It is not preferable since it can not be easily fixed in the form of a jelly-roll.

The position where the perforated line is formed is also not limited as long as it is broken at an expansion range in which the radius is increased by 3% to 30%. However, the present invention is not limited thereto. Specifically, when the electrode assembly is inflated, In one specific example, the perforation line may be formed within a range of 10% of the circumferential length of the electrode assembly with respect to the winding end of the electrode assembly.

In another specific example, the perforation line may be formed at a position corresponding to the winding end of the electrode assembly.

That is, when the seal tape is broken by forming the perforated line at the winding end portion or the adjacent portion of the electrode assembly, the stress at the winding end portion where the generation of the stress is most severe can be solved and the unwinding of the winding end portion is not restricted, It is possible to effectively reduce the stress on the outer periphery of the electrode assembly due to the space in which the assembly expands. As a result, it is possible to prevent disconnection of the electrode.

Meanwhile, in one specific example, the battery case of the secondary battery according to the present invention is not limited as long as it is a material capable of housing the electrode assembly, but may be a cylindrical or rectangular metal can in detail.

Hereinafter, other components of the secondary battery will be described.

The positive electrode is prepared, for example, by coating a mixture of a positive electrode active material, a conductive material and a binder on a positive electrode current collector, and then drying the mixture. Optionally, a filler may be further added to the mixture.

The cathode current collector is generally made to have a thickness of 3 to 500 micrometers. Such a positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical change in the battery, and may be formed of a material such as stainless steel, aluminum, nickel, titanium, sintered carbon, or a surface of aluminum or stainless steel Treated with carbon, nickel, titanium, silver or the like may be used. The current collector may have fine irregularities on the surface thereof to increase the adhesive force of the cathode active material, and various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric are possible.

The cathode active material may be a layered compound such as lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals; Lithium manganese oxides such as Li _{1 + x} Mn _{2 -x} O ₄ (where x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO ₂ and the like; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ and Cu ₂ V ₂ O ₇ ; A Ni-site type lithium nickel oxide expressed by the formula LiNi _1-x M _x O ₂ (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga and x = 0.01 to 0.3); Formula _{LiMn 2-x M x O 2} ( where, M = Co, Ni, Fe , Cr, and Zn, or Ta, x = 0.01 ~ 0.1 Im) or Li ₂ Mn ₃ MO ₈ (where, M = Fe, Co, Ni, Cu, or Zn); LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with an alkaline earth metal ion; Disulfide compounds; Fe ₂ (MoO ₄ ) ₃ , and the like. However, the present invention is not limited to these.

The conductive material is usually added in an amount of 1 to 30% by weight based on the total weight of the mixture including the cathode active material. Such a conductive material is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, for example, graphite such as natural graphite or artificial graphite; Carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fiber and metal fiber; Metal powders such as carbon fluoride, aluminum, and nickel powder; Conductive whiskey such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used.

The binder is a component which assists in bonding of the active material and the conductive material and bonding to the current collector, and is usually added in an amount of 1 to 30% by weight based on the total weight of the mixture containing the cathode active material. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene , Polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butylene rubber, fluorine rubber, various copolymers and the like.

The filler is optionally used as a component for suppressing the expansion of the anode, and is not particularly limited as long as it is a fibrous material without causing a chemical change in the battery. Examples of the filler include olefin polymers such as polyethylene and polypropylene; Fibrous materials such as glass fibers and carbon fibers are used.

The negative electrode is manufactured by applying and drying a negative electrode active material on a negative electrode collector, and if necessary, the above-described components may be selectively included.

The negative electrode collector is generally made to have a thickness of 3 to 500 micrometers. Such an anode current collector is not particularly limited as long as it has conductivity without causing chemical change in the battery, and may be formed of a material such as copper, stainless steel, aluminum, nickel, titanium, fired carbon, surface of copper or stainless steel A surface treated with carbon, nickel, titanium, silver or the like, an aluminum-cadmium alloy, or the like can be used. In addition, like the positive electrode collector, fine unevenness can be formed on the surface to enhance the bonding force of the negative electrode active material, and it can be used in various forms such as films, sheets, foils, nets, porous bodies, foams and nonwoven fabrics.

Examples of the negative electrode active material include carbon such as non-graphitized carbon and graphite carbon; _{Li x Fe 2 O 3 (0≤x≤1} ), Li x WO 2 (0≤x≤1), Sn x Me 1-x Me 'y O z (Me: Mn, Fe, Pb, Ge; Me' : Metal complex oxides such as Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, Halogen, 0 < x < Lithium metal; Lithium alloy; Silicon-based alloys; Tin alloy; _{SnO, SnO 2, PbO, PbO} 2, Pb 2 O 3, Pb 3 O 4, Sb 2 O 3, Sb 2 O 4, Sb 2 O 5, GeO, GeO 2, Bi 2 O 3, Bi 2 O 4, and Bi ₂ O ₅ ; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials and the like can be used.

The separation membrane is interposed between the anode and the cathode, and an insulating thin film having high ion permeability and mechanical strength is used. The pore diameter of the membrane is generally 0.01 to 10 micrometers, and the thickness is generally 5 to 300 micrometers. Such separation membranes include, for example, olefinic polymers such as polypropylene, which are chemically resistant and hydrophobic; A sheet or nonwoven fabric made of glass fiber, polyethylene or the like is used. When a solid electrolyte such as a polymer is used as an electrolyte, the solid electrolyte may also serve as a separation membrane.

The electrolytic solution may be a non-aqueous electrolytic solution containing a lithium salt, and is composed of a non-aqueous electrolytic solution and a lithium salt. As the non-aqueous electrolyte, non-aqueous organic solvents, organic solid electrolytes, inorganic solid electrolytes, and the like are used, but the present invention is not limited thereto.

Examples of the non-aqueous organic solvent include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma -Butyrolactone, 1,2-dimethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane , Acetonitrile, nitromethane, methyl formate, methyl acetate, triester phosphate, trimethoxymethane, dioxolane derivatives, sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate Nonionic organic solvents such as tetrahydrofuran derivatives, ethers, methyl pyrophosphate, ethyl propionate and the like can be used.

Examples of the organic solid electrolyte include a polymer electrolyte such as a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, an agitation lysine, a polyester sulfide, a polyvinyl alcohol, a polyvinylidene fluoride, Polymers containing ionic dissociation groups, and the like can be used.

Examples of the inorganic solid electrolyte include Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N-LiI-LiOH, LiSiO ₄ , LiSiO ₄ -LiI-LiOH, Li ₂ SiS ₃ , Li ₄ SiO ₄ , Nitrides, halides and sulfates of Li such as Li ₄ SiO ₄ -LiI-LiOH and Li ₃ PO ₄ -Li ₂ S-SiS ₂ can be used.

The lithium salt is a material that is readily soluble in the non-aqueous electrolyte, for example, LiCl, LiBr, LiI, LiClO 4, LiBF 4, LiB 10 Cl 10, LiPF 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF _{6, LiSbF 6, LiAlCl 4,} CH 3 SO 3 Li, CF 3 SO 3 Li, (CF 3 SO 2) 2 NLi, chloroborane lithium, lower aliphatic carboxylic acid lithium, lithium tetraphenyl borate and imide have.

For the purpose of improving the charge-discharge characteristics and the flame retardancy, the nonaqueous electrolytic solution is preferably a solution prepared by dissolving or dispersing in a solvent such as pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, hexaphosphoric triamide, N, N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, aluminum trichloride and the like may be added have. In some cases, halogen-containing solvents such as carbon tetrachloride and ethylene trifluoride may be further added to impart nonflammability. In order to improve the high-temperature storage characteristics, carbon dioxide gas may be further added. FEC (Fluoro-Ethylene Carbonate, PRS (Propene sultone), and the like.

In one specific _{example, LiPF 6, LiClO 4, LiBF} 4, LiN (SO 2 CF 3) 2 , such as a lithium salt, a highly dielectric solvent of DEC, DMC or EMC Fig solvent cyclic carbonate and a low viscosity of the EC or PC of And then adding it to a mixed solvent of linear carbonate to prepare a lithium salt-containing non-aqueous electrolyte.

The present invention also provides a battery pack including two or more of the secondary batteries as unit cells and a device using the battery pack as a power source.

Specific examples of the device according to the present invention may be, but not limited to, a mobile phone, a tablet PC, a notebook computer, a power tool, an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or a power storage device.

The structure and manufacturing method of such a device are well known in the art, so a detailed description thereof will be omitted herein.

As described above, in the secondary battery according to the present invention, the seal tape having the self-breaking portion is fixedly attached to the outer surface of the electrode assembly. Therefore, when the electrode assembly is housed in the battery case, It is possible to prevent the expansion of the electrode assembly due to the self-break of the seal tape in the situation where the electrode assembly expands due to charge and discharge of the secondary battery. Therefore, the stress generated at the winding end portion and the outer frame portion of the electrode assembly As a result, the cause of short-circuiting of the electrode can be prevented, and the safety of the secondary battery can be improved.

1 is a schematic view of a prismatic secondary battery having an electrode assembly according to an embodiment of the present invention;
Figure 2 is a perspective view of the electrode assembly of Figure 1;
3 is a perspective view of an electrode assembly according to another embodiment of the present invention;
4 is a schematic view of a cylindrical secondary battery having an electrode assembly according to an embodiment of the present invention;
Figure 5 is a perspective view of the electrode assembly of Figure 4;
6 is a schematic view showing a process of breaking the seal tape according to the expansion of the electrode assembly of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited by the scope of the present invention.

FIG. 1 schematically shows a prismatic secondary battery having an electrode assembly according to an embodiment of the present invention. Referring to FIG.

 Referring to FIG. 1, the secondary battery 200 includes a positive electrode tab 102 and a negative electrode tab 101 protruding from the upper surface of the electrode assembly, A rectangular metal case 110 in which the jelly-roll type electrode assembly 100 is attached and a top cap 120 in which a protruding negative electrode terminal 122 is formed at an open upper end of the case 110 Lt; / RTI >

The negative electrode of the electrode assembly 100 is electrically connected to the lower end of the negative electrode terminal 122 on the upper cap 120 through the negative electrode tab 101. The negative electrode terminal 122 is electrically connected to the upper cap 120 by the insulating member 121, (120). On the other hand, another electrode (for example, an anode) of the electrode assembly 100 is electrically connected to the upper cap 120 whose anode tab 102 is made of a conductive material such as aluminum, stainless steel, Thus, the top cap 120 itself forms a bipolar terminal.

The secondary battery 200 includes a rectangular case 110 and an electrode assembly 100 to ensure the electrical insulation between the electrode assembly 100 and the upper cap 120 except for the positive electrode tab 102 and the negative electrode tab 101. [ The insulator 130 is inserted between the top cap 120 and the case 110 and then welded together by welding along the contact surface between the top cap 120 and the case 110. Then, After the electrolyte is injected, it is welded, sealed, and assembled by applying a welding part with epoxy or the like.

FIG. 2 is a perspective view of the electrode assembly of FIG. 1 for explaining a jelly-roll type electrode assembly according to the present invention.

2, the electrode assembly 100 includes a sealing tape 103 on the upper surface of the positive electrode tab 102 and the negative electrode tab 101 protruding from the lower surface of the electrode assembly, And is attached to the seal tape 103 in such a manner as to wrap around the winding end portion 105 which is the winding end portion of the electrode assembly 100. The seal tape 103 is provided with a perforated line 104, Respectively.

The sealing tape 103 prevents the winding end 105 of the electrode assembly 100 from being unwound in the process of housing the electrode assembly 100 in the case 110 to prevent the electrode assembly 100 from being jelly- It can be fixed with a roll. This is not only facilitated in housing the electrode assembly 100 in the case 110 but also facilitating the deactivation of the electrode resulting in the remaining space between the electrode sheets .

The perforated line 104 formed on the seal tape 103 is formed in a direction parallel to the winding end portion 105. When the electrode assembly is inflated oppositely to the winding direction of the electrode assembly 100, It can be broken.

The perforated line 104 may be formed on the seal tape 103 before attachment to the electrode assembly 100 or may be formed after attaching the seal tape 103 to the electrode assembly 100, It can vary depending on volume.

3 is a perspective view of an electrode assembly according to another embodiment of the present invention.

3, the electrode assembly 100 includes an electrode assembly 100 having an upper surface on which the positive electrode tab 102 and the negative electrode tab 101 are protruded, And the seal tape 203 is formed with a plurality of perforated lines 204 in a direction parallel to the winding end at a position substantially coincident with the rewind end 105. [ With this structure, even when the seal tape 204 is broken, the electrical insulation of most of the side surfaces of the electrode assembly can be ensured, and therefore, the seal tape 204 exhibits an excellent effect in terms of safety.

FIG. 4 is a schematic view of a cylindrical secondary battery incorporating an electrode assembly according to another embodiment of the present invention, and FIG. 5 is a perspective view of the electrode assembly of FIG.

Referring to these drawings, a cylindrical battery 400 includes a cylindrical battery case 420, an electrode assembly 300 accommodated in the battery case 420, and a cap assembly 430 coupled to an upper portion of the battery case 420 ).

The electrode assembly 300 is in the form of a jelly-roll wound with a separator interposed between the positive electrode and the negative electrode. The positive electrode lead 422 is attached to the positive electrode and connected to the cap assembly 430, A seal tape 303 is attached to the electrode assembly 300 (not shown) on the side surfaces of the electrode assembly 300 on which the positive electrode lead 422 and the negative electrode lead are attached, And a winding end portion 305 which is a winding end portion. The seal tape 303 is formed with a plurality of discontinuous perforated lines 304 at positions coincident with the rewind end 305.

FIG. 6 schematically illustrates a process of breaking the seal tape due to expansion of the electrode assembly when the electrode assembly of FIG. 5 performs charge / discharge in order to explain the breakage shape of the seal tape having the perforated line according to the present invention.

6, a seal tape 303 is attached to the electrode assembly 300 that is not charged and discharged, and a plurality of perforated lines 304 are formed on the seal tape 303. The electrode assembly 300a after the charge or discharge is first or several times started to expand and the perforated line 304a does not maintain the shape of the initial perforated line 304 according to the expansion of the electrode assembly 300a and a part thereof is broken. Further, when charging / discharging further proceeds, the electrode assembly 300b expands rapidly and completely breaks the perforated line 304b.

That is, when the electrode assembly 300a expands due to repeated charging and discharging, the seal tape 303 expands together with the electrode assembly, and when the expanding force of the electrode assembly 300 becomes more than the tensile force of the seal tape 303 The perforated line 304 having a relatively low tensile strength is broken.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.

Claims (16)

A jelly-roll type electrode assembly in which a positive electrode and a negative electrode including an active material coated portion are wound on at least one surface of a current collector with a separator interposed therebetween;
A battery case in which the electrode assembly is housed;
An electrolyte contained in the battery case together with the electrode assembly; And
A seal tape having a winding end portion of the electrode assembly fixedly attached to an outer surface of the electrode assembly and having a self-breaking portion broken due to an expansion stress when the electrode assembly expands due to charging and discharging;
And a secondary battery. The secondary battery according to claim 1, wherein the positive electrode and the negative electrode of the electrode assembly each have a positive electrode tab and a negative electrode tab attached to an uncoated portion of the current collector having no active material coating portion. The secondary battery according to claim 1, wherein the seal tape is made of an electrically insulating polymer resin. The secondary battery according to claim 1, wherein the seal tape is attached while covering the entire side surface except the upper surface of the electrode assembly protruded from the electrode tab and the lower surface opposed thereto. The seal tape according to claim 1, wherein the seal tape is attached while covering an area of 5 to 60% based on the total area of the side surface, excluding the upper surface of the electrode assembly protruding from the electrode tab and the lower surface opposed thereto And a secondary battery. The secondary battery according to claim 1, wherein the self-breaking portion is broken in an expansion range in which the radius of the electrode assembly increases by 3% to 30%. The secondary battery according to claim 1, wherein the self-breaking portion is at least one perforated line formed continuously or discontinuously on the seal tape. The secondary battery according to claim 7, wherein the perforated line is formed parallel to the winding end of the electrode assembly. The rechargeable battery of claim 7, wherein the self-breaking portion comprises two or more perforated lines formed discontinuously. The secondary battery according to claim 7, wherein the perforated line is formed within a range of 10% of the outer circumferential length of the electrode assembly with respect to the winding end of the electrode assembly. The secondary battery according to claim 7, wherein the perforated line is formed at a position corresponding to the winding end of the electrode assembly. The secondary battery according to claim 7, wherein the total length of the perforated line is 10 to 70% of the length of the seal tape. The secondary battery according to claim 1, wherein the battery case is a cylindrical or rectangular metal can. The battery pack according to claim 1, wherein the secondary battery comprises two or more unit cells. A device comprising a battery pack according to claim 14. 16. The device of claim 15, wherein the device is a mobile phone, a tablet PC, a notebook computer, a power tool, an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or a power storage device.

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