KR101558250B1 - Fixation Device for Checking Defect of Electrode Assembly and Method of Checking the Same - Google Patents

Abstract

An apparatus for fixing an electrode assembly for selecting the presence or absence of an electrode assembly including an electrode terminal, the apparatus comprising: a base plate on which an electrode assembly is mounted; A first jig for pressing the center of the electrode assembly in a flat state in a state where the electrode assembly is mounted on the base plate and a second jig for pressing the opposite side portions of the central portion in a planar state with the electrode assembly mounted on the base plate And a pair of second jigs for pressurizing the second jig.

Description

Technical Field [0001] The present invention relates to a fixing device for selecting an electrode assembly and a method for selecting a defective electrode assembly,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a fixing device for detecting the presence / absence of an electrode assembly, and a method for selecting a defective electrode assembly using the same. More particularly, A base plate on which the electrode assembly is mounted; a first jig for pressing the central portion of the electrode assembly in a flat state with the electrode assembly mounted on the base plate; And a pair of second jigs for pressurizing both side portions of the central portion in plan view, respectively.

2. Description of the Related Art As technology development and demand for mobile devices have increased, the demand for secondary batteries as energy sources has been rapidly increasing, and a lot of research has been conducted on secondary batteries that can meet various demands.

Typically, from the viewpoint of the shape of the secondary 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 cellular phones with a small thickness, and a high energy density, a discharge voltage, There is a high demand for lithium secondary batteries such as lithium ion batteries and lithium ion polymer batteries.

In addition, the secondary battery is classified according to the structure of the anode assembly, the cathode assembly, and the electrode assembly having the separator structure sandwiched between the anode assembly and the cathode assembly. Typically, (Stacked) electrode assembly in which a plurality of positive electrodes and negative electrodes cut in a unit of a predetermined size are sequentially stacked with a separator interposed therebetween, a jelly-roll (wound type) electrode assembly having a structure A stack / folding type electrode assembly in which unit cells such as a bi-cell or a full cell stacked with a separator interposed between positive and negative electrodes of a unit are wound.

Figures 1 and 2 schematically illustrate an exemplary structure and fabrication of such a stack / foldable electrode assembly.

Referring to these drawings, a plurality of pull cells 10, 11, 12, 13, 14, ... each having a positive electrode / separator / negative electrode laminated sequentially as unit cells are superimposed, Respectively. The separating film 20 has a unit length that can wrap around the pull cell and is bent inward for each unit length and starts from the center pull cell 10 and continues from the outermost pull cell 14 to each of the pull cells, Respectively. The distal end of the separation film 20 is thermally fused or bonded with an adhesive tape 25 or the like.

This stack / folding type electrode assembly is formed by arranging the pull cells 10, 11, 12, 13, 14 ... on the long length of the separation film 20 and separating the separation films 20 at one end 21 ) And then winding them sequentially.

The first pull cell 10 and the second pull cell 11 are located at a distance separated by a width corresponding to at least one pull cell, The lower surface electrode of the first pull cell 10 is brought into contact with the upper surface electrode of the second pull cell 11 after the outer surface of the first pull cell 10 is completely coated with the separation film 20.

Meanwhile, the stack / folding type electrode assembly may suffer from damage to the separator due to various reasons such as negligence in operation or errors in the process of mounting the separator on the separator film and the winding process, There is a problem that a part of the surface of the electrode is exposed from the separation membrane due to the occurrence of defects such as partially folding or folding in one direction of the separation membrane of the winding start portion, There is a problem that the performance of the battery deteriorates.

In order to solve such a problem, some prior arts use a flat jig to pressurize the plane of the completed stack / folding type electrode assembly and apply a current to induce a short circuit of the exposed electrode from the separation membrane, And the like. However, when the flat plate jig for pressing the flat surface of the electrode assembly is used as described above, it is difficult to cause short-circuiting of the exposed electrode due to a relatively low pressing force due to a wide pressing area. Particularly, It is difficult to effectively select defective electrode exposure due to the membrane folding phenomenon.

Therefore, there is a high need for a technology that can fundamentally solve these problems.

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.

It is an object of the present invention to provide a fixing device for selecting a presence or absence of defects included in a defective measuring device for selecting whether or not a defective electrode assembly is additionally included so that both sides on the plane of the electrode assembly are effectively pressurized, The present invention also provides a fixing device for selecting a faulty or non-defective screening device capable of performing more accurate screening at the time of screening.

It is still another object of the present invention to provide a method of selecting whether an electrode assembly is defective by properly measuring the internal short-circuit of the electrode assembly and accurately selecting whether there is a defect, thereby improving product yield and ensuring high yield .

In order to accomplish the above object, there is provided an apparatus for fixing an electrode assembly for identifying a defect in an electrode assembly including an electrode terminal,

A base plate on which the electrode assembly is mounted;

A first jig for pressurizing a central portion of the electrode assembly in a flat state with the electrode assembly mounted on the base plate; And

A pair of second jigs for respectively pressing both side portions of the center portion in a planar state with the electrode assembly mounted on the base plate;

As shown in FIG.

Therefore, the defective presence / absence fixing device according to the present invention further includes a pressing portion having a narrow contact surface, thereby effectively pressing both sides of the electrode assembly plane, thereby detecting defective through internal short circuit measurement that may occur in the folding process of the electrode assembly More accurate selection is possible.

In one preferred embodiment, the pressing force per unit area by the second jig may be greater than the pressing force per unit area by the first jig at the pressing portion of the electrode assembly. Specifically, the pressing force per unit area by the second jig is May be 101% to 200% of the pressing force per unit area by one jig.

Since the folding phenomenon of the separator that may occur at the time of winding of the stack / folding type electrode assembly generally corresponds to both sides of the completed electrode assembly, the unit of the second jig pressing the both sides on the plane of the electrode assembly, It is preferable that the pressing force per area is larger than that of the first jig.

Therefore, it is possible to effectively pressurize the electrode assembly by the pressing of the first jig and the second sheet, and it is possible to induce a short-circuit of the electrode exposed from the separation membrane inside the electrode assembly, thereby selecting a defect.

In one specific example, the first jig and second jig may have a plate-like shape at the end of which the electrode assembly is pressed, and preferably the second jig and the second jig, And their ends may be circular or semi-circular in vertical section.

In addition, the second sheet may have a structure that presses the outermost sides of both sides of the electrode assembly, so that a cross-section for pressing both sides on the plane of the electrode assembly may pressurize the narrow contact surfaces of the both sides to maximize the local pressing force. With this structure, the electrode assembly can be effectively pressed, and the defective presence / absence discriminating force can be improved.

The first jig has a structure that presses the central portion of the electrode assembly in a plane. Specifically, the first jig has a length smaller than the length of the surface on which the electrode terminals of the electrode assembly are located, The branch may be a structure.

Therefore, not only short-circuit induction due to the folding phenomenon of the separator, which may occur at the time of winding the electrode assembly by the second jig, but also short-circuiting of the electrode exposed by the damage of the separator surface can be caused.

The electrode assembly is not particularly limited as long as it has a structure in which a plurality of electrode tabs are connected to form an anode, a cathode, and a separator. Specifically, a plurality of electrodes or unit cells with an anode, a cathode, And a stack / folding structure of a structure in which a continuous separator sheet is wound and wound on each of the overlapping portions. Details of the stacked / folded structure of the electrode assembly are disclosed in Korean Patent Application Laid-Open Nos. 2001-0082058, 2001-0082059 and 2001-0082060, the contents of which are incorporated herein by reference. As a reference.

In one specific example, the unit cell has a structure in which one or more positive electrodes and one or more negative electrodes are stacked with a separator interposed therebetween, and the type of electrodes disposed on both sides, It may be another pool cell.

The electrode plates or the unit cells may have a structure in which the electrode terminals are stacked so as to be arranged on the upper or lower side or the electrode terminals are arranged in the upper side and the first electrode terminal is arranged, And two electrode terminals are stacked so as to be arranged.

Meanwhile, the present invention provides a defective presence / absence discriminator including the defect detection / non-presence fixing device and a failure measuring device for selecting the defect of the electrode assembly with the electrode assembly positioned in the fixing device.

In addition, in the present invention, there is provided a method of selecting the defective or non-defective electrode assembly using the defective / non-defective separator according to the present invention. In one preferred embodiment, the electrode assembly is positioned on the defective / non- process; Applying a current to an electrode terminal of the electrode assembly; And determining whether the electrode assembly is short-circuited.

For reference, a typical lithium secondary battery is composed of a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte containing a lithium salt.

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 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.

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 separator is generally 0.01 to 10 mu m and the thickness is generally 5 to 300 mu m. 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 non-aqueous electrolyte solution containing a lithium salt is composed of a polar organic electrolyte and a lithium salt. As the electrolytic solution, a non-aqueous liquid electrolytic solution, an organic solid electrolyte, an inorganic solid electrolyte and the like are used.

Examples of the nonaqueous liquid electrolytic solution 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, sulfates and the like 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 non-aqueous liquid electrolyte may contain, 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. are added It is possible. In some cases, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride may be further added to impart nonflammability, or a carbon dioxide gas may be further added to improve high-temperature storage characteristics.

The present invention also provides a battery cell including an electrode assembly in which defects are selected by the above method, and the battery pack includes at least two battery cells as a unit cell. Also, the present invention provides a device including the battery pack as a power source, wherein the device is a mobile phone, a portable computer, a smart phone, a tablet PC, a smart pad, a netbook, a LEV (light electronic vehicle), an electric vehicle, , A plug-in hybrid electric vehicle, and a power storage device.

The structure of these devices and their fabrication methods are well known in the art, and a detailed description thereof will be omitted herein.

As described above, according to the present invention, there is provided a fixing apparatus for selecting a presence / absence of defects, which includes pressing portions for pressing the central portion of the electrode assembly, pressing portions having relatively narrow contact surfaces for detecting the defects of the electrode assembly, There is an effect that it is possible to more precisely sort the electrode assemblies when the two sides of the electrode assembly plane are effectively pressed to check whether there is a defect in the electrode assembly due to a short circuit.

1 is a schematic diagram of an exemplary structure of a stack / folding type electrode assembly;
FIG. 2 is a schematic diagram illustrating an exemplary arrangement of unit cells in a manufacturing process of the stack / folding type electrode assembly of FIG. 1; FIG.
Figs. 3 to 4 are photographs showing the winding start timing of the electrode assembly of Fig. 1 in which a separation membrane failure occurs; Fig.
FIG. 5 is a schematic view of a fixing apparatus for selecting a faulty one according to an embodiment of the present invention.

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. 5 is a schematic view of a fixing apparatus for selecting a faulty one according to an embodiment of the present invention.

5, a fixing apparatus 100 for detecting a presence / absence of a defect according to the present invention includes a base plate 130 on which an electrode assembly 140 is mounted, a base plate 130 on which the electrode assembly 140 is mounted, A first jig 110 for pressing the center of the electrode assembly on a plane on the base plate 130 and a first jig 110 for pressing the both sides of the center portion in a planar state with the electrode assembly 140 mounted on the base plate 130 And a pair of second jigs 121 and 122, respectively.

The defective presence / absence discriminating device 100 is disposed on the base plate 130 and is disposed on the positive electrode terminal 141 and the negative electrode terminal 142 of the electrode assembly 130 in a state of being pressed after the electrode assembly 130 is positioned. Current is applied to measure whether the electrode assembly 140 is short-circuited.

Since the ends of the first and second jigs 121 and 122, which press the electrode assembly, have a semi-elliptical shape in a vertical section, the first jig 110 is formed in a flat shape, So that both sides of the central region can be pressed with a relatively large pressure.

Although the jigs 110, 121, and 122 shown in FIG. 5 are described as being composed of the members for pressing the rectangular electrode assembly in which electrodes of the same size or capacity are wound, the jigs 110, 121, 122 may have various sizes and shapes depending on the size and shape of the electrode assembly.

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

≪ Example 1 >

Manufacture of electrode assembly

A positive electrode mixture slurry was prepared by adding N-methyl-2-pyrrolidone (NMP) as a solvent to 95 wt% of LiCoO ₂ , 2.5 wt% of Super-P (conductive agent) and 2.5 wt% of PVdF (binder) A negative electrode mixture slurry was prepared by adding 95 wt% of artificial graphite, 2.5 wt% of Super-P (conductive agent) and 2.5 wt% of PVdF (binder) as a negative active material to NMP as a solvent, Coated, dried and pressed to prepare a positive electrode and a negative electrode.

Using the cell guard ^TM as a separator, and was equipped with the positive electrode and the negative electrode, and 7 by the cell as the cell guard ^TM of the same material as the separation membrane as the back, the separation film is configured for bi-cell is laminated to the membrane in order, and the bi-cell Folded defective electrode assembly in which one side of the separation membrane of the winding start portion of the separation membrane is folded is set to 20, and the partially folded defective electrode assembly in which one side of the separation membrane at the winding start portion of the separation membrane is partially folded is set to 60, To produce 80 folding defective electrode assemblies.

Manufacture of faulty separator

There is provided an apparatus for fixing an electrode assembly for identifying the presence or absence of an electrode assembly including an electrode terminal, the apparatus comprising: a base plate on which an electrode assembly is mounted; A fixing device including a pair of second jigs for pressurizing both side portions of the central portion in a plane in a state in which the first jig and the electrode assembly for pressing are mounted on the base plate, And a failure measuring device for selecting the failure of the electrode assembly with the electrode assembly positioned in the fixation device.

≪ Comparative Example 1 &

The defective separator was manufactured in the same manner as in Example 1, except that the fixing device was manufactured without the second jig.

<Experimental Example 1>

A total of 80 short-circuit defective electrode assemblies manufactured using the defective and non-defective separators manufactured in Example 1 and Comparative Example 1 were measured, and the results are shown in Table 1 below.

Bad Type Overall screening rate (%) Date Folding Screening Rate (%) (Number of Screening / Number of Setting) Partial Folding Screening Rate (%) (Number of Screening / Number of Setting) Example 1 100% (20/20ea) 93.3% (56 / 60ea) 95.0% Comparative Example 1 25% (5/20e) 3.3% (2 / 60ea) 8.8%

As shown in Table 1, when the defective / non-defective separator of Example 1 was used, the screening rate was 100% at defective folding in the day, 93.3% in case of partial folding deficiency, and the overall screening rate was 95.0% In contrast, in the case of using the defective separator of Comparative Example 1, a screening ratio of 25% was shown in the case of defective folding, and 3.3% in case of partial folding failure, and the overall screening rate was found to be 8.8%.

That is, it can be seen from Table 1 that the defective / non-defective separator of Example 1 shows significantly higher selectivity than the defective / non-defective separator of Comparative Example 1, indicating that the defective It is possible to confirm that the both side portions on the plane of the electrode assembly are effectively pressurized by the addition of the pressing portion having a relatively narrow contact surface relative to the presence / absence sorting fixing device, .

It will be understood by those skilled 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)

An apparatus for fixing an electrode assembly for selecting the presence or absence of defects in an electrode assembly including an electrode terminal,
A base plate on which the electrode assembly is mounted;
A first jig for pressurizing a central portion of the electrode assembly in a flat state with the electrode assembly mounted on the base plate; And
A pair of second jigs for respectively pressing both side portions of the center portion in a planar state with the electrode assembly mounted on the base plate;
And a fixing unit for fixing the defect. The fixing device according to claim 1, wherein the pressing force per unit area by the second jig is larger than the pressing force per unit area by the first jig at the pressing position of the electrode assembly. 3. The apparatus according to claim 2, wherein the pressing force per unit area by the second jig is 101% to 200% of the pressing force per unit area by the first jig. The apparatus according to claim 1, wherein the presence or absence of failure is determined by the presence or absence of shorting of the electrode assembly due to the pressing of the first jig and the second paper. The fixing device for a faulty and faulty sorting apparatus according to claim 1, wherein the first jig and the second jig are plate-shaped at their end portions for pressing the electrode assembly. The fixing device for defective and non-defective products according to claim 1, wherein the second member has a circular or semicircular shape in a vertical cross section at an end portion for pressing the electrode assembly. The fixing device according to claim 1, wherein the first jig has a length smaller than a length of a surface on which the electrode terminal of the electrode assembly is located and a length equal to a surface perpendicular to the surface on which the electrode terminal is located. The fixing device according to claim 1, wherein the second pads press the outermost sides of both sides of the electrode assembly. The electrode assembly according to claim 1, wherein the electrode assembly has a structure in which a plurality of electrodes or unit cells with an anode, a cathode, and a separator interposed therebetween are stacked and a continuous separator sheet is wound on each of the overlapped portions The fixing device for defective and non-defective products. [12] The unit cell according to claim 9, wherein the unit cell has a structure in which at least one positive electrode and at least one negative electrode are stacked with a separator interposed therebetween, Wherein the B-type unit cell is a B-type unit cell of different type. 10. The apparatus according to claim 9, wherein the unit cells are laminated so that electrode terminals are arranged at the same position. 12. The apparatus according to any one of claims 1 to 11, further comprising a failure detector for selecting whether there is a defect in the electrode assembly with the electrode assembly positioned in the fixation apparatus. Selector. A method for selecting the defective or non-defective electrode assembly using the defective and non-defective separator according to claim 12,
Positioning the electrode assembly on the fixing device for defective presence / absence and pressing the electrode assembly;
Applying a current to an electrode terminal of the electrode assembly; And
Measuring a short circuit of the electrode assembly;
&Lt; / RTI &gt; The battery cell according to claim 13, further comprising an electrode assembly which is selected for the presence or absence of defects. The battery pack according to claim 14, comprising at least two battery cells as unit cells. A device comprising the battery pack according to claim 15 as a power source. 17. The method of claim 16, wherein the device is selected from the group consisting of a mobile phone, a portable computer, a smart phone, a tablet PC, a smart pad, a netbook, a LEV (Light Electronic Vehicle), an electric vehicle, a hybrid electric vehicle, &Lt; / RTI &gt; device.

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