KR101752329B1 - Secondary Battery with Advanced Safety - Google Patents

Abstract

The present invention relates to a laminate sheet including a resin layer and a metal layer, wherein the battery case has a positive electrode / separator / negative electrode assembly embedded therein, the electrode tab of the electrode assembly is coupled to the electrode lead and protrudes outside the battery case, Wherein the foamed adhesive is mounted in a structure that surrounds a joint portion ("tab-lead joint portion") of the electrode tab and the electrode lead and the opposite surface of the electrode assembly.

Description

[0001] The present invention relates to a secondary battery with an improved safety,

The present invention relates to a secondary battery with improved safety.

As technology development and demand for mobile devices are increasing, the demand for secondary batteries as energy sources is rapidly increasing. Among such secondary batteries, lithium secondary batteries having high energy density and voltage, long cycle life and low self- It has been commercialized and widely used.

Such a lithium secondary battery may be classified as a lithium ion battery, a lithium ion polymer battery, or a lithium polymer battery depending on the configuration of an electrode and an electrolytic solution. The lithium secondary battery is less liable to leak electrolyte, Is increasing. Lithium ion polymer battery (LiPB) is a structure in which an electrolyte solution is impregnated in an electrode assembly in which an electrode (an anode and a cathode) and a separator are thermally fused, and is often used as a form in which a stacked electrode assembly is sealed in a pouch case of an aluminum laminate sheet have. Therefore, a lithium ion polymer battery is often referred to as a pouch type battery.

Figures 1 and 2 schematically illustrate a typical structure of a representative LiPB that includes a stacked electrode assembly.

Referring to these figures, the LiPB 100 has an electrode assembly 300 including an anode, a cathode, and a separator disposed therebetween in a pouch-shaped battery case 200, (301, 302) are welded to the two electrode leads (400, 410) and sealed so as to be exposed to the outside of the battery case (200).

The battery case 200 is made of a soft packaging material such as an aluminum laminate sheet and includes a case body 210 including a concave shaped housing part 230 on which the electrode assembly 300 can be placed, And a lid 220 to which one side is connected.

The electrode assembly 300 used in the LiPB 100 may have a jelly-roll structure other than the stacked structure shown in FIG. The stacked electrode assembly 300 includes a plurality of positive electrode tabs 301 and a plurality of negative electrode tabs 302 welded to the electrode leads 400 and 410 and the electrode leads 400 and 410 are welded to the battery case 200 An insulation film 500 is attached to the upper and lower surfaces to ensure electrical insulation and sealing properties.

Such a lithium secondary battery such as LiPB may cause a short circuit due to exposure to high temperature, overcharge, external short circuit, nail penetration, local crush, drop, etc., There is a risk of ignition / explosion as the battery is heated. When the temperature of the battery rises, the reaction between the electrolyte and the electrode is accelerated. As a result, a reaction heat is generated and the temperature of the battery further rises, which again accelerates the reaction between the electrolyte and the electrode. Therefore, the temperature of the battery rapidly increases, which again accelerates the reaction between the electrolyte and the electrode. Such a vicious circle causes a thermal runaway phenomenon in which the temperature of the battery rises sharply, and when the temperature rises to a certain level or higher, the battery may ignite. Further, as a result of the reaction between the electrolyte and the electrode, gas is generated and the internal pressure of the battery is increased, and the lithium secondary battery explodes at a certain pressure or higher. The risk of such ignition and explosion is the most fatal disadvantage of lithium secondary batteries.

In particular, LiPB is easily deformed due to dropping, external impact, etc. due to the battery case being made of a soft packaging material having a weak strength. 1B, a space 230a for connecting the electrode tabs to the electrode leads 400 and 410 by welding is present on the upper end of the electrode assembly 300 of the battery case 200, (Mainly an anode) of the electrode leads 400 and 410 move to the top of the electrode assembly 300 while the electrode assembly 300 moves to the top space 230a when an impact is applied from the top direction of the electrode assembly 300. [ An internal short circuit may be caused by contacting the outermost electrode (mainly the negative electrode collector) or the top of the electrode assembly. Since the drop of the battery is a phenomenon that occurs frequently during use of the battery, there is a high need for a technique for securing the safety of the battery in a more efficient manner.

In order to solve the above problem, in order to prevent an internal short-circuit due to movement of the electrode assembly, a method of attaching the adhesive tape to a part of the electrode assembly or inserting a foreign substance into the upper space of the electrode assembly is used. However, the above-described method has a problem of reducing the performance of the battery because it induces a chemical reaction between the adhesive tape and the electrolyte.

Therefore, a secondary battery having a specific structure capable of solving the above problems is very much needed.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned 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 not only the contact area between the electrode lead and the battery case but also the area where the electrode tab and the electrode lead are coupled and the entire area except the electrode tab part, It has been confirmed that an internal short circuit can be effectively prevented by fundamentally wrapping it with an adhesive, thereby completing the present invention.

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 positive electrode / separator / negative electrode assembly embedded in a battery case of a laminate sheet including a resin layer and a metal layer, And the electrically insulating foamed adhesive covers the opposing surfaces of the electrode tabs and the electrode tabs and the electrode tabs.

Therefore, the secondary battery according to the present invention is structured such that the electrically insulating foamable adhesive wraps around the joint portion ("tab-lead joint portion") of the electrode tab and the electrode lead and the entire opposing face of the electrode assembly, Even if the same external impact is applied to the secondary battery, the internal short circuit can be prevented while maintaining the maximum performance of the battery.

As described above, in an ordinary pouch-type secondary battery, when the electrode assembly is mounted on the battery case of the laminate sheet, the electrode tab is V-formed to increase the space efficiency and connected to the electrode lead. In this process, a short circuit may occur between the electrode and the electrode constituting the outermost part of the electrode assembly due to impact, falling, etc. The electrode constituting the outermost part of the electrode assembly may be a positive electrode or a negative electrode, And a negative electrode for the balance of the battery design between the cathodes, especially for safety reasons.

In addition, the conventional pouch-type secondary battery has a larger separation membrane size than the negative electrode, thereby primarily preventing the risk of short-circuiting. However, in order to prevent a short circuit even when the positive electrode lead penetrates the separator, the secondary battery of the present invention is applied to the electrode tab and the electrode lead of the electrode assembly and the entire opposing surface of the electrode assembly with an electrically insulating foaming adhesive Or spraying it to cure it, it has the advantage of being capable of fundamentally preventing a short circuit due to an external impact such as falling while maintaining the performance of the battery to the maximum.

In one preferred embodiment, the electrode assembly is a stacked electrode assembly in which a plurality of positive electrodes and negative electrodes are stacked with a separator interposed therebetween. The tab-lead coupling portion includes a plurality of electrode tabs (a positive electrode tab or a negative electrode tab) (Positive electrode lead or negative electrode lead) to be bonded to each other.

In another preferred embodiment, the electrode assembly is a stack / folding type electrode assembly in which unit cells of a bi-cell or pull-cell structure are wound by a separation film. The tab- Negative electrode tab) may be welded to one electrode lead (positive lead or negative lead).

The bi-cell has a basic structure of an anode / separator / cathode / separator / anode or a cathode / separator / anode / separator / cathode, where the electrodes on both sides of the outermost periphery have the same electrode. The pull cell has unit cells having opposite electrodes on the outermost sides, and have a basic structure of a cathode / separator / cathode.

In the present invention, the foamable adhesive is preferably applied independently to the tab-lead bonding portion of the positive electrode and the tab-lead bonding portion of the negative electrode, but may be applied simultaneously if necessary.

The foamable adhesive is preferably formed by spraying or coating, but is not limited thereto.

In a specific example, the foamable adhesive is made of a material which is cured at 10 to 150 ° C. Examples of the adhesive include an epoxy resin adhesive, a phenol resin adhesive, a polyester resin adhesive, a polyimide resin adhesive, a urethane adhesive, A resin adhesive, an acrylic resin adhesive, or the like can be used, and these can be used singly or in combination of two or more.

Therefore, the entire opposing surface of the electrode assembly as well as the electrode tab and the electrode lead are coated or injected by the foamable adhesive and cured, thereby preventing the electrode assembly from flowing in the battery case.

The thickness of the foamable adhesive prior to curing is preferably from 50 micrometers to 3000 micrometers, but may be variously selected depending on the conditions of use. For example, the joining portion of the electrode tab and the electrode lead and the entire space of the opposing surface of the electrode assembly may be filled with the foamable adhesive.

In one preferred example, the foamable adhesive may be formed on the entire opposite surface of the electrode assembly except for the electrode tab portion. Therefore, it is possible to cut off the short circuit inside the battery.

In a specific example, the foamable adhesive may be cured after 5 to 60 seconds after being applied or sprayed so as to wrap the tab-lead bonding portion and the opposite surface of the electrode assembly.

Generally, in a pouch type battery, an insulating film is attached to a contact portion between an electrode lead and a battery case. In this case, it is preferable that the foamable adhesive of the present invention is applied or sprayed continuously to the lower side of the insulating film.

Meanwhile, in the present invention, the electrode tab may have a structure in which the separator is prevented from being damaged by a foaming adhesive and extended from the top of the collector. In one preferred example, the extended length may be 2 to 8 mm.

The electrode assembly of the present invention is an electrode assembly having a high risk of short-circuiting as described above. For example, the electrode assembly includes a stacked structure in which a plurality of electrode plates are laminated with a separator formed thereon, A stacked / folded structure of a structure in which a substrate is wound with a separation film, but the present invention is not limited thereto.

The secondary battery according to the present invention is not particularly limited as long as the electrode assembly is mounted on the battery case of the laminate sheet, but it may preferably be a lithium secondary battery.

Such a lithium secondary battery is composed of a positive electrode, a negative electrode, an electrolyte and the like as is well known in the art and will be described in detail below.

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

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 cathode current collector generally has a thickness of 3 to 500 mu m. 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 conductive agent is usually added in an amount of 1 to 50% by weight based on the total weight of the mixture including the cathode active material. Such a conductive agent is not particularly limited as long as it has electrical conductivity without causing a chemical change in the battery, and examples thereof include graphite such as natural graphite and 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 that assists in bonding of the active material and the conductive agent to the binder and in binding to the current collector, and is usually added in an amount of 1 to 50% 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 a negative electrode material on the negative electrode collector and drying the same, and if necessary, the above-described components may further be included.

The negative electrode collector is generally made to have a thickness of 3 to 500 mu m. 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.

The negative electrode material may be, for example, carbon such as non-graphitized carbon or 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 &lt; 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 non-aqueous electrolyte containing a lithium salt is composed of a solvent for a nonaqueous electrolyte and a lithium salt. Examples of the solvent include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, But are not limited to, lactone, 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 derivatives, Tetrahydrofuran derivatives, ether, methyl pyrophosphate, ethyl propionate and the like 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.

In some cases, organic solid electrolytes, inorganic solid electrolytes, etc. may 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.

For the purpose of improving charge / discharge characteristics, flame retardancy, etc., non-aqueous electrolytes may be used in the form of, for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, N, N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, aluminum trichloride and the like are added It is possible. 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), FPC (fluoro-propylene carbonate), and the like.

The present invention also provides a battery pack including the secondary battery, wherein the battery pack is used as an electric power source, and the electric vehicle, the hybrid electric vehicle, or the plug-in hybrid electric vehicle having a limited installation space and exposed to frequent vibration, Provide a car.

It goes without saying that battery packs used as power sources for automobiles can be manufactured in combination according to a desired output and capacity.

Electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, etc. using battery packs as power sources are well known in the art, and a detailed description thereof will be omitted.

As described above, in the secondary battery according to the present invention, the internal short-circuit caused by the contact between the cathode lead, which is frequently generated during dropping, and the cathode located at the outermost portion of the electrode assembly, (Tap-lead connecting portion) of the lead and the entire opposing face of the electrode assembly are wrapped with an electrically insulating foamable adhesive, there is an effect that fundamentally can be prevented.

The secondary battery according to the present invention has the effect of preventing the electrode assembly from flowing in the battery case by applying the foamed adhesive to the entire opposing surfaces of the tab-lead connecting portion and the electrode assembly and then curing.

Further, the secondary battery according to the present invention can increase the upper space of the battery case by forming the entire opposing surfaces of the tab-lead connection portion including the V-Forming portion to which the foamable adhesive is applied and the electrode assembly with a desired width, It is effective.

1 and 2 are a perspective view showing a process of assembling a battery case and an electrode assembly in a conventional lithium ion polymer battery using a pouch-shaped battery case and a plan view in an assembled state;
3 is a plan view schematically showing an upper end portion of an electrode assembly in a secondary battery according to an embodiment of the present invention.
4 is a vertical cross-sectional schematic diagram of an electrode assembly according to one embodiment of the present invention.

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

FIG. 3 schematically shows an upper end portion of an electrode assembly in a secondary battery according to an embodiment of the present invention.

3, an electrode assembly 300 having a separator 330 interposed between a positive electrode current collector 310 and a negative electrode current collector 320 on which electrode active materials are coated on both surfaces, 310 and 320 protrude from the upper end of the cathode tab 301 and the cathode tab 302, respectively.

Since the electrode assembly 300 is composed of a plurality of cathodes and anodes, a plurality of the cathode tabs 301 and the anode tabs 302 are welded to the cathode lead 400 and the cathode lead 410, respectively. Thus, the tab-lead coupling portions 401 and 411 are formed at the lower ends of the electrode leads 400 and 410 and at the upper ends of the electrode tabs 301 and 302, respectively.

The tab-and-lid coupling portions 410 and 411 may be formed at the upper end or the outermost electrode of the electrode assembly 300 when the battery is dropped and the electrode assembly 300 moves, To cause an internal short circuit.

Therefore, a foamable adhesive 600 is attached so as to cover the entire upper end facing surface 340 of the tab-and-lid coupling portions 401 and 411 and the electrode assembly 300.

The foamable adhesive 600 is continuously attached to the lower end of the insulating film 500 attached to the electrode leads 400 and 410 and is electrically connected to the cathode lead 400 and the anode lead 500, (410).

It is difficult to stably attach a member such as an insulating film to the tab-and-lid coupling portions 401 and 411. However, the foamed adhesive 600 and the electrode assembly 300 are formed by wrapping the entire outer surface of the upper facing surface 340 of the electrode assembly 300 The electrode assembly 300 can be stably wrapped over the entire upper opposing surface 340 as well as the tab-and-lid joints 401 and 411 by being coated or sprayed.

The electrode leads 400 and 410 may be welded to the electrode tabs 301 and 302 in a state where the insulating film 500 is previously attached to the corresponding portions of the electrode leads 400 and 410 or after welding to the electrode tabs 301 and 302 The insulating film 500 may be adhered to the insulating film 500.

The electrode tabs 301 and 302 extend a little longer from the electrode current collectors 310 and 320 so that the tab-and-lid coupling portions 401 and 411 are separated from the upper ends of the electrode current collectors 310 and 320 by such extension lengths . Therefore, the foamable adhesive 510 surrounding the tab-and-lead coupling portions 401 and 411 and the upper opposing face 340 of the electrode assembly 300 may damage the separator 330 of the electrode assembly 300 It provides high safety without.

4 is a vertical cross-sectional schematic diagram of an electrode assembly according to one embodiment of the present invention.

4, a plurality of cathode tabs 301 protruding from the upper end of an anode 310 are ultrasonically welded to one cathode lead 400, and a heat sealing (not shown) of a pouch type battery case An insulating film 500 is attached on the cathode lead 400 corresponding to the sealing portion. The insulating film 500 enhances the sealing property while securing the insulating property to the cathode lead 400 when the battery case (not shown) is sealed by mutual heat sealing. The relationship between the negative electrode taps 302 and the negative electrode leads 410 is also the same as described above.

The electrode assembly 300 has a separator 330 interposed between the positive and negative electrode current collectors 310 and 320 and the outermost electrode is composed of the negative electrode 320.

In the electrode assembly 300, the separator 330 is larger than the cathode 320 in terms of safety and the cathode 320 is formed larger than the anode 310 in terms of battery design balance. Therefore, the risk of short-circuiting can be primarily prevented by the separation membrane 330 which is larger than the cathode 320. However, only the configuration of the electrode assembly 300 can not prevent a short circuit when the separator 330 is thermally deformed at a high temperature, or when the cathode lead penetrates the separator 330.

In contrast, in the present invention, the entire surface of the electrode assembly 300 where the electrode tabs and the electrode leads are coupled and the upper opposing surface 340 of the electrode assembly 300 are coated or sprayed using an electrically insulating foam adhesive 600, The cathode tab 320 and the positive electrode tab 301 are prevented from short-circuiting due to an impact or the like, thereby providing a secondary battery with improved safety.

Accordingly, as described above, it is possible to fundamentally prevent an internal short circuit due to an external impact or the like due to a structure that is more effectively applied or sprayed on the connection portions of the tab-leads and the opposite surfaces of the electrode assembly.

Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims (15)

Separator / negative electrode assembly is embedded in a battery case of a laminate sheet including a resin layer and a metal layer. The electrode tab of the electrode assembly is coupled to the electrode lead and protrudes to the outside of the battery case, and an electrically insulating foamable adhesive (The "tab-lead coupling portion") of the electrode tab and the electrode lead and the opposing surface of the electrode assembly,
The tab-and-lid coupling portion is formed by welding a plurality of electrode tabs (positive electrode tab or negative electrode tab) to one electrode lead (positive lead or negative lead)
Wherein the foamable adhesive is mounted on the tab-lead coupling portion of the positive electrode and the tab-lead coupling portion of the negative electrode, respectively,
Wherein the foamable adhesive is formed on the entire opposite surface of the electrode assembly except for the electrode tab,
Wherein the joint portion of the electrode tab and the electrode lead and the entire space of the opposing surface of the electrode assembly are filled with the foamable adhesive. The secondary battery according to claim 1, wherein the electrode assembly is a stacked electrode assembly in which a plurality of positive electrodes and a plurality of negative electrodes are stacked with a separator interposed therebetween. The secondary battery according to claim 1, wherein the electrode assembly is a stack / folding type electrode assembly in which unit cells of a bi-cell or pull-cell structure are wound by a separation film. delete The secondary battery according to claim 1, wherein the foamable adhesive is formed by spraying or coating. The secondary battery according to claim 1, wherein the foamable adhesive is made of a material which is cured at 10 to 150 ° C. The secondary battery according to claim 1, wherein the foamable adhesive is an epoxy resin adhesive, a phenol resin adhesive, a polyester resin adhesive, a polyimide resin adhesive, a urethane resin adhesive, or an acrylic resin adhesive. The secondary battery according to claim 1, wherein the thickness of the foamable adhesive is 50 micrometers to 3000 micrometers. delete The secondary battery according to claim 1, wherein the foamable adhesive is cured after 5 seconds to 60 seconds after being applied or sprayed so as to cover the tab-lead coupling portion and the opposite surface of the electrode assembly. The secondary battery according to claim 1, wherein an insulating film is attached to a contact portion between the electrode lead and the battery case. The secondary battery according to claim 1, wherein the electrode tab is elongated from an upper end of the collector to prevent the separation membrane from being damaged by a foaming adhesive. 13. The secondary battery according to claim 12, wherein an extension length of the electrode tab is 2 to 8 mm. A battery pack comprising the secondary battery according to claim 1. 15. The battery pack according to claim 14, wherein the battery pack is used as a power source for an electric vehicle, a hybrid electric vehicle, an electric bicycle, and an electric motorcycle.

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