KR101627360B1 - Secondary Battery Comprising Member for Disconnect - Google Patents

Abstract

The present invention relates to a positive electrode current collector comprising at least one positive electrode having a positive electrode tab formed on at least one end of a positive electrode current collector coated on one side or both sides of the positive electrode active material, One or more negative electrodes having a negative electrode portion formed on at least one end of the negative electrode current collector coated on one surface or both surfaces of the negative electrode active material to form a negative electrode tab on the uncoated portion; And at least one separator interposed between the positive electrode and the negative electrode to mutually isolate the positive electrode and the negative electrode, the electrode assembly being sealed inside the battery case together with the electrolyte solution,
The positive electrode tab and the negative electrode tab are respectively welded to the positive electrode collector and the negative electrode collector,
Wherein the positive electrode tab and / or the negative electrode tab includes a unit member.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a secondary battery,

The present invention relates to a secondary battery including a member for power generation.

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.

Among these secondary batteries, there is a demand for a prismatic battery and a pouch type battery which can be applied to products such as cellular phones with a thin thickness in terms of shape, and a lithium ion battery having high energy density, discharge voltage, There is a high demand for secondary batteries such as polymer batteries.

Generally, a secondary battery includes an electrode assembly composed of a cathode, a cathode, and a separator interposed between the anode and the cathode, which is laminated or wrapped in a battery case of an aluminum can or a laminate sheet in a state of being wound and then injected or impregnated with an electrolyte have.

One of the major research tasks in such secondary batteries is to improve safety. For example, a secondary battery can have a high temperature and / or high temperature inside the battery that can be caused by an abnormal operating condition of the battery, such as an internal short circuit, an overcharged condition exceeding an allowable current and voltage, exposure to a high temperature, The explosion of the battery may be caused by high pressure.

On the other hand, when the scale of the lithium ion battery is medium or large, the shape of the polymer battery cell is advantageous in terms of energy density. In the case of a polymer battery cell, current is applied by connecting a positive current collector and a negative current collector with one tap.

In particular, in the case of a large-capacity, large-capacity battery cell such as an automobile, if there is a large resistance in the battery or when the battery is heated from the outside, When the reaction of the combustible electrolyte accelerates due to the rise of the temperature, the explosion of the electrolyte accelerates and the explosive force is considerably large. Therefore, in order to use the battery as an actual product, solving the safety problem is urgent.

Therefore, a need exists for a technique capable of solving such a problem.

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. As described later, the positive electrode tab and the negative electrode tab are respectively welded to the positive electrode collector and the negative electrode collector, and the positive electrode tab and / It has been confirmed that a desired effect can be attained by including this unit element, and the present invention has been accomplished.

Accordingly, the secondary battery according to the present invention is a secondary battery comprising: at least one anode in which a cathode tab is formed on at least one end of a cathode current collector coated with a cathode active material on one or both surfaces thereof, One or more negative electrodes having a negative electrode portion formed on at least one end of the negative electrode current collector coated on one surface or both surfaces of the negative electrode active material to form a negative electrode tab on the uncoated portion; And at least one separator interposed between the positive electrode and the negative electrode to mutually isolate the positive electrode and the negative electrode, the electrode assembly being sealed inside the battery case together with the electrolyte solution,

The positive electrode tab and the negative electrode tab are respectively welded to the positive electrode collector and the negative electrode collector,

And the positive electrode tab and / or the negative electrode tab includes a unit member.

The positive electrode tab and the negative electrode tab are in the form of a pair of metal members joined together, and the unit member may be included in the joint surface of the pair of metal members.

The secondary battery according to the present invention may further comprise at least one anode having a cathode tab formed on at least one end of the cathode current collector coated on one side or both sides of the cathode active material, One or more negative electrodes having a negative electrode portion formed on at least one end of the negative electrode current collector coated on one surface or both surfaces of the negative electrode active material to form a negative electrode tab on the uncoated portion; And at least one separator interposed between the positive electrode and the negative electrode to mutually isolate the positive electrode and the negative electrode, the electrode assembly being sealed inside the battery case together with the electrolyte solution,

The positive electrode tab and the negative electrode tab are respectively welded to the positive electrode collector and the negative electrode collector,

And a cut-off member in the form of a bead is included between the positive electrode tab and the positive electrode collector of the welded portion and / or between the negative electrode tab and the negative electrode collector.

The unit element may be at least one member selected from the group consisting of micropearls in the form of beads.

The micropulle contains hydrocarbons, and a coating layer of a thermoplastic resin is formed on the surface, and the overall shape is a bead shape. In this micropulle, when the temperature rises, the internal hydrocarbon is expanded in volume, and the surface area of the thermoplastic resin coating layer having a good elongation rate is also increased.

The diameter of the unit member may be not less than 5 micrometers and not more than 50 micrometers.

The unit member may bulge at a temperature of 100 degrees Celsius or more to cause a short circuit between the current collector and the tab. In particular, the unit member may bulge at a temperature of 130 degrees Celsius or more to cause a short circuit between the current collector and the tab.

The volume expansion of the unit member may be two or more times, and more specifically, the volume expansion of the unit member may be three times or more.

The thickness of the positive electrode tab and the negative electrode tab may be 0.2 mm or more and 0.5 mm or less.

The positive electrode collector and the negative electrode collector of the positive electrode tab and the negative electrode tab may be welded by any one selected from the group consisting of laser welding, resistance welding, ultrasonic welding, arc welding and gas welding.

The positive electrode collector and the positive electrode tab, and the negative electrode collector and the negative electrode tab may be made of the same metal.

The cathode active material may include a lithium transition metal oxide expressed by the following general formula (1) or (2).

Li _x M _y Mn _{2 - y} O _{4 - z z} (1)

In this formula,

M is at least one element selected from the group consisting of Al, Mg, Ni, Co, Fe, Cr, V, Ti, Cu, B, Ca, Zn, Zr, Nb, Mo, Sr, Sb, W, ;

A is one or more anions of -1 or -2;

0.9? X? 1.2, 0 <y <2, 0? Z <0.2.

(1-x) LiM'O _2-y A _y -xLi ₂ MnO _{3 -y '} A _y' (2)

In this formula,

M 'is Mn _a M _b ;

M is one or more selected from the group consisting of Ni, Ti, Co, Al, Cu, Fe, Mg, B, Cr, Zr, Zn and two period transition metals;

A is at least one selected from the group consisting of anions of PO ₄ , BO ₃ , CO ₃ , F and NO ₃ ;

0 <x <1, 0 <y? 0.02, 0 <y? 0.02, 0.5? A? 1.0, 0 b? 0.5, a + b =

In one specific example, the negative electrode active material may include a carbon-based material, and / or Si.

In one specific example, the secondary battery may be a lithium ion battery, a lithium ion polymer battery, or a lithium polymer battery.

The present invention provides a battery module including the secondary battery as a unit cell, a battery pack including the battery module, and a device including the battery pack as a power source.

At this time, the device may be an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or a system for power storage.

Generally, the positive electrode is prepared by applying an electrode mixture, which is a mixture of a positive electrode active material, a conductive material and a binder, on a positive electrode collector, followed by drying. If necessary, 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 ) or lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals, in addition to the lithium transition metal oxide represented by Formula 1 or 2. 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); A lithium manganese composite oxide having a spinel structure represented by LiNi _x Mn _2-x O ₄ ; 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, but is not limited thereto.

The cathode current collector generally has a thickness of not less than 3 micrometers and not more than 500 micrometers. Such a positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. Examples of the positive electrode current collector include stainless steel, aluminum, nickel, titanium, sintered carbon, aluminum or stainless steel A surface 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 material 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 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.

On the other hand, the graphite-based material having elasticity may be used as a conductive material, and may be used together with the materials.

The binder is a component that 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 50 wt% 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 lithium secondary batteries generally include an anode, a cathode, a separator interposed between the anode and the cathode, and a non-aqueous electrolyte containing a lithium salt. Other components of the lithium secondary battery will be described below.

The negative electrode is prepared by applying, drying and pressing an anode active material on an anode current collector, and may optionally further include a conductive material, a binder, a filler, and the like as described above.

The negative electrode active material may include, 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 &lt; 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; Titanium oxide; Lithium titanium oxide and the like can be used, and in particular, a carbon-based material and / or Si can be included.

The negative electrode current collector is generally made to have a thickness of not less than 3 micrometers and not more than 500 micrometers. Such an anode current collector is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, and examples of the anode current collector include copper, stainless steel, aluminum, nickel, titanium, sintered carbon, a 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 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 separator is generally not less than 0.01 micrometer to 10 micrometers, and the thickness is generally not less than 5 micrometers and not more than 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 lithium salt-containing nonaqueous electrolyte is composed of a nonaqueous electrolyte and lithium. Nonaqueous organic solvents, organic solid electrolytes, inorganic solid electrolytes, and the like are used as the nonaqueous electrolyte, 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, A polymer containing an ionic dissociation group and the like may 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 2) 2 NLi, chloroborane lithium, lower aliphatic carboxylic acid lithium, lithium tetraphenyl borate and imide.

The lithium salt-containing non-aqueous electrolyte may further contain, for the purpose of improving charge / discharge characteristics, flame retardancy, etc., for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, N, N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, aluminum trichloride, etc. May be added. 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 provides a battery module including the secondary battery as a unit cell, a battery pack including the battery module, and a device including the battery pack as a power source.

At this time, specific examples of the device include a power tool that is powered by an electric motor and moves; An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and the like; An electric motorcycle including an electric bike (E-bike) and an electric scooter (E-scooter); An electric golf cart; And a power storage system, but the present invention is not limited thereto.

As described above, in the secondary battery according to the present invention, the positive electrode tab and the negative electrode tab are welded to the positive electrode collector and the negative electrode collector, respectively, and the positive electrode tab and / When the internal temperature of the secondary battery is increased to a predetermined temperature or more (for example, 100 ° C to 130 ° C), the unit member expands in volume to induce physical disconnection of the positive electrode tab and / or the negative electrode tab. Can be secured.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing a change in volume of a micropearl included in a secondary battery according to an embodiment of the present invention; FIG.
2 is a graph showing the temperature-dependent volume changes of various types of micropearls of the present invention;
3 is a schematic perspective view of an electrode assembly A in which a micropile is inserted into a positive electrode tab and a negative electrode tab according to an embodiment of the present invention;
4 is a schematic cross-sectional view illustrating a phenomenon in which an electrode assembly A according to an embodiment of the present invention undergoes a disconnection according to a volume change according to a temperature of a micropearl;
5 is a schematic perspective view of an electrode assembly B in which a micropearl is inserted into a positive electrode tab and a negative electrode tab according to another embodiment of the present invention;
FIG. 6 is a schematic cross-sectional view illustrating a phenomenon in which an electrode assembly B according to an embodiment of the present invention undergoes a disconnection according to a volume change according to the temperature of a micropearl.

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 is a graph showing a volume change according to a temperature of a micropearl included in a secondary battery according to an embodiment of the present invention. FIG. 2 is a graph showing a volume change Fig.

Referring to FIG. 1, it can be seen that the micropulse according to the present invention has a characteristic of causing a volume expansion only at a certain temperature (for example, 100 ° C. to 130 ° C.).

Referring to FIG. 2, various volume expansion ratios are shown depending on the types of micro pearls, and in the case of micro pearls B and micro pearls D, a volume expansion of up to 9 times occurs. Therefore, the secondary battery according to the present invention can be applied to the positive electrode tab or the negative electrode tab by selecting an appropriate micropearl in consideration of the internal structure of the secondary battery.

FIG. 3 is a schematic perspective view of an electrode assembly A 100 in which a micropulle is inserted into a positive electrode tab and a negative electrode tab according to an embodiment of the present invention.

3, an uncoated portion 126 is formed on at least one end of a positive electrode current collector coated on one or both surfaces of a positive electrode active material 122, and a positive electrode tab 124 is formed on the uncoated portion 126 In which an uncoated portion 136 is formed on at least one end of an anode current collector coated on one or both surfaces of a cathode 120 and a cathode active material 132 and a cathode tab 134 is formed on the non- Or more of the cathode 130 is formed.

The positive electrode tab 124 and the negative electrode tab 134 are respectively welded to the positive electrode collector and the negative electrode collector and the positive electrode tab 124 and the negative electrode tab 134 include a micropearl 140 have.

Here, the positive electrode tab 124 and the negative electrode tab 134 are formed by joining together a pair of metal members, and the microperes 140 are included inside the joining faces of the pair of metal members.

FIG. 4 is a schematic cross-sectional view illustrating a phenomenon in which the electrode assembly A 100 according to an embodiment of the present invention undergoes a disconnection according to a change in volume according to the temperature of a micropearl.

4, a micro pearl 140 is inserted inside the joint surface 162 of the pair of metal members 160 of FIG. 4. As the internal temperature of the battery rises, a volume expansion occurs, The joining surface 162 is separated, and thus a disconnection can be achieved.

5 shows a schematic perspective view of an electrode assembly B 200 in which a micropearl 140 is inserted into a positive electrode tab 224 or a negative electrode tab 234 according to another embodiment of the present invention. Sectional views illustrating a phenomenon in which the electrode assembly B 200 according to an embodiment of the present invention has a disconnection according to a volume change according to the temperature of the micro pearl 140.

5 and 6, a micropearl 140, which is a unit member, is included between the positive electrode tab 224 of the welded portion and the positive electrode collector 272, and between the negative electrode tab 234 and the negative electrode collector 282 have.

6, the micropile 140 is inserted into the bonding surface 262 of the metal member 260 of the positive electrode tab 224 and the positive electrode collector 272. As the internal temperature of the battery rises, So that the joint surface 262 of the metal member 260 is separated, so that a disconnection can be achieved.

Therefore, when the secondary battery is manufactured using the electrode assembly of FIGS. 3 and 5, the volume expansion of the micropearl occurs as the internal temperature of the battery rises, thereby inducing physical disconnection of the positive electrode tab or the negative electrode tab The current can be prevented from flowing further.

It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (17)

At least one anode having a cathode tab formed on at least one end of a cathode current collector coated on one or both surfaces of the cathode active material, One or more negative electrodes having a negative electrode portion formed on at least one end of the negative electrode current collector coated on one surface or both surfaces of the negative electrode active material to form a negative electrode tab on the uncoated portion; And at least one separator interposed between the positive electrode and the negative electrode to mutually isolate the positive electrode and the negative electrode, the electrode assembly being sealed inside the battery case together with the electrolyte solution,
The positive electrode tab and the negative electrode tab are respectively welded to the positive electrode collector and the negative electrode collector,
Wherein the positive electrode tab, or negative electrode tab, or positive electrode tab and negative electrode tab include a unit member,
Wherein the positive electrode tab and the negative electrode tab are formed by joining a pair of metal members, wherein the cutaway member is included in a joint surface of the pair of metal members,
The unit member bulges at a temperature of 100 degrees Celsius or more to cause a short circuit between the current collector and the tab,
Wherein the cutoff member is at least one member selected from the group consisting of micropearls in the form of beads, and the diameter of the cutoff member is 5 micrometers or more to 50 micrometers or less. delete At least one anode having a cathode tab formed on at least one end of a cathode current collector coated on one or both surfaces of the cathode active material, One or more negative electrodes having a negative electrode portion formed on at least one end of the negative electrode current collector coated on one surface or both surfaces of the negative electrode active material to form a negative electrode tab on the uncoated portion; And at least one separator interposed between the positive electrode and the negative electrode to mutually isolate the positive electrode and the negative electrode, the electrode assembly being sealed inside the battery case together with the electrolyte solution,
The positive electrode tab and the negative electrode tab are respectively welded to the positive electrode collector and the negative electrode collector,
Wherein a cutoff member is included between the positive electrode tab and the positive electrode collector of the welded portion or between the negative electrode tab and the negative electrode collector or between the positive electrode tab and the positive electrode collector and between the negative electrode tab and the negative electrode collector,
The unit member bulges at a temperature of 100 degrees Celsius or more to cause a short circuit between the current collector and the tab,
Wherein the cutoff member is at least one member selected from the group consisting of bead-shaped micropearls, and the cutoff member has a diameter of 5 micrometers or more to 50 micrometers or less. delete delete delete The secondary battery according to claim 1, wherein a volume expansion of the unit member is twice or more. The secondary battery according to claim 1 or 3, wherein the thickness of the positive electrode tab and the negative electrode tab is 0.2 mm or more to 0.5 mm or less. The method as claimed in claim 1 or 3, wherein the positive electrode collector and the negative electrode collector of the positive electrode tab and the negative electrode tab are welded to one another selected from the group consisting of laser welding, resistance welding, ultrasonic welding, arc welding and gas welding And a secondary battery. The secondary battery according to claim 1 or 3, wherein the positive electrode collector and the positive electrode tab, and the negative electrode collector and the negative electrode tab are made of the same metal. The secondary battery according to claim 1 or 3, wherein the cathode active material comprises a lithium transition metal oxide represented by the following formula (1) or (2)
Li _x M _y Mn _{2 - y} O _{4 - z z} (1)
In this formula,
M is at least one element selected from the group consisting of Al, Mg, Ni, Co, Fe, Cr, V, Ti, Cu, B, Ca, Zn, Zr, Nb, Mo, Sr, Sb, W, ;
A is one or more anions of -1 or -2;
0.9? X? 1.2, 0 <y <2, 0? Z <0.2.


(1-x) LiM'O _2-y A _y -xLi ₂ MnO _{3 -y '} A _y' (2)
In this formula,
M 'is Mn _a M _b ;
M is one or more selected from the group consisting of Ni, Ti, Co, Al, Cu, Fe, Mg, B, Cr, Zr, Zn and two period transition metals;
A is at least one selected from the group consisting of anions of PO ₄ , BO ₃ , CO ₃ , F and NO ₃ ;
0 <x <1, 0 <y? 0.02, 0 <y? 0.02, 0.5? A? 1.0, 0 b? 0.5, a + b = The secondary battery according to claim 1 or 3, wherein the negative electrode active material comprises a carbon-based material and / or Si. The secondary battery according to claim 1 or 3, wherein the secondary battery is a lithium ion battery, a lithium ion polymer battery, or a lithium polymer battery. A battery module comprising a secondary battery according to any one of claims 1 to 3 as a unit cell. A battery pack comprising the battery module according to claim 14. The device according to claim 15, comprising the battery pack as a power source. 17. The device of claim 16, wherein the device is an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or a system for power storage.

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