KR101614332B1 - Battery Cell of Irregular Structure - Google Patents

Abstract

The present invention relates to a positive electrode, a negative electrode, and a first electrode group having a structure in which a separation membrane is interposed between the positive electrode and the negative electrode; And a second electrode group mounted in a state where a separation membrane is interposed between the upper and / or lower ends of the first electrode group, wherein the electrode assembly is housed in a battery case, Wherein the first opening is perforated and a second opening is drilled in the center of the second group of electrodes, the first opening and the second opening are in communication with each other, and the end of the second opening is provided with an upwardly or downwardly extending protrusion And a first opening is attached to the protruding portion.

Description

[0001] The present invention relates to a battery cell of irregular structure,

The present invention relates to an unstructured battery cell, and more particularly, to a non-volatile battery cell including a positive electrode, a negative electrode, and a first electrode group having a structure in which a separator is interposed between the positive electrode and the negative electrode; And a second electrode group mounted in a state where a separation membrane is interposed between the upper and / or lower ends of the first electrode group, wherein the electrode assembly is housed in a battery case, Wherein the first opening is perforated and a second opening is drilled in the center of the second group of electrodes, the first opening and the second opening are in communication with each other, and the end of the second opening is provided with an upwardly or downwardly extending protrusion And a first opening is mounted to the protruding portion.

The lithium secondary battery is classified into a cylindrical battery, a prismatic battery, a pouch-type battery, and the like depending on the outer shape thereof, and may be classified into a lithium ion battery, a lithium ion polymer battery, and a lithium polymer battery depending on the type of electrolyte.

Due to recent trends toward miniaturization of mobile devices, there is a growing demand for thin rectangular prismatic batteries and pouch-shaped cells, and particularly for pouch-shaped cells which are easy to deform in shape, low in manufacturing cost, Interest is high.

Generally, a pouch-type battery refers to a battery in which an electrode assembly and an electrolyte are sealed inside a pouch-shaped case of a laminate sheet composed of a resin layer and a metal layer. The electrode assembly housed in the battery case has a jelly-roll type (wound type), a stacked type (stacked type), or a composite type (stacked / folded type) structure.

FIG. 1 schematically shows a structure of a pouch-shaped battery cell including a conventional stacked electrode assembly.

1, the battery cell 10 includes a rectangular electrode assembly 30, electrode tabs 40 and 50 extending from the electrode assembly 30, electrodes 40 and 50 welded to the electrode tabs 40 and 50, Leads 60 and 70, and a battery case 20 for accommodating the electrode assembly 30. [

The electrode assembly 30 is a power generation element in which an anode and a cathode are sequentially stacked with a separator interposed therebetween, and has a stacked structure. The electrode tabs 40 and 50 extend from each electrode plate 30 of the electrode assembly 30 and the electrode leads 60 and 70 are connected to a plurality of electrode tabs 40 and 50 extending from each electrode plate, Respectively, and a part of the battery case 20 is exposed to the outside. An insulating film 80 is attached to the upper and lower surfaces of the electrode leads 60 and 70 in order to increase the degree of sealing with the battery case 20 and at the same time to ensure an electrically insulated state.

The battery case 20 is made of an aluminum laminate sheet, provides a space for accommodating the electrode assembly 30, and has a pouch shape as a whole. In the case of the stacked electrode assembly 30 as shown in FIG. 1, the battery case 20 is formed so that a plurality of the anode tabs 40 and the plurality of anode tabs 50 can be coupled to the electrode leads 60, The inner top is spaced from the electrode assembly 30.

However, the battery cell of the above structure is an optimized form of a general rectangular device, and it is difficult to efficiently utilize the internal space of the device when it is applied to various types of devices, for example, circular, elliptical or complicated geometry type devices There are disadvantages.

In addition, since the above-described battery cells include an electrode assembly having the same size or capacity, in order to obtain a novel structure considering the design of a device to which the battery cell is applied, it is necessary to reduce the capacity of the battery cell, There is a problem that the design of the device needs to be changed.

Therefore, in recent years, a new type of battery cell is required due to a slim shape or a trend change of various designs.

Accordingly, in some prior arts, a battery cell is formed by stacking electrodes having different sizes, or a battery cell is formed by stacking electrodes having openings, thereby changing the design of the battery cell to correspond to various types of devices.

However, in order to fabricate a battery cell having a desired size, the battery cell requires very precise dimensional stability when the electrodes are stacked. In particular, in the case of stacking electrodes with openings, There is a problem such as inconsistency. Therefore, there is a disadvantage that the battery cell of the above structure requires a fixing member or manual work for dimensional stability. In addition, since the electrical connection method of the battery cell is complicated, it is also difficult to manufacture a battery cell satisfying a desired condition.

Therefore, there is a high need for a battery cell that can solve the above problems, be applicable to various types of devices, and is easy to manufacture.

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.

Specifically, it is an object of the present invention to provide a battery cell that is applicable to shapes and spaces of various devices, and is easily manufactured while ensuring dimensional stability.

According to an aspect of the present invention, there is provided a battery cell comprising: a first electrode group having a cathode, a cathode, and a separator interposed between the anode and the cathode; And a second electrode group mounted in a state where a separation membrane is interposed between the upper end and / or the lower end of the stack of the first electrode group, wherein the electrode assembly is built in a battery case,

Wherein a first opening is drilled in the center of the first electrode group, a second opening is drilled in the center of the second electrode group, the first opening and the second opening are in communication with each other, Wherein a protrusion extending upward or downward is formed, and a first opening is mounted on the protrusion.

That is, since the battery cell according to the present invention is formed with an opening in a predetermined shape, a part of the device, which is bent or indented, can be received inside the opening, But also the other members of the device, for example, an electric circuit or a washer, can be accommodated through the opening of the battery cell, so that the utilization of the internal space of the device is very high.

Also, since the battery cells are stacked in such a manner that the first openings are mounted on the upwardly or downwardly extending protrusions formed in the second openings, it is easy to stack the electrode groups without a separate fixing member or manual operation As a result, the present invention can provide a battery cell with high dimensional safety.

The volume of the battery cell can be designed in consideration of the desired battery capacity and the size of the device. Generally, the volume of the battery cell can be determined according to the number of stacked electrode groups constituting the electrode assembly. In this case, the electrode assembly may include one or more first electrode groups and one or two second electrode groups. More specifically, the electrode assembly may include one or more first electrode groups and two second electrode groups Can be.

The second electrode group may be a single electrode of a positive electrode or a negative electrode, or may be in the form of an electrode group having a structure in which a separation membrane is interposed between an anode and a cathode, such as a first electrode group.

The first electrode group and the second electrode group may be stacked, for example, a plurality of first electrode groups may be stacked on top of one second electrode group, and two first electrode groups may be stacked on top of one first electrode group. Second electrode groups may be stacked. In addition, the first electrode group may be stacked on top of the second electrode group stack in a state where the two second electrode groups are stacked on each other. As a result, And may include an electrode assembly composed of various laminated structures.

At this time, the first electrode group and the second electrode group are formed such that the upper end of the second electrode group is mounted on the lower end of the stack of the first electrode group with the upward protrusion of the second opening inserted in the first opening Lt; / RTI > The second electrode group may be mounted on the upper end of the stack of the first electrode group with the lower end of the stack of the first electrode group being inserted into the first opening while the downward protrusion of the second opening is inserted into the first opening.

As described above, in the electrode assembly according to the present invention, the first electrode group and the second electrode group are laminated in a state where the first opening is fixed by the projecting portion, and the electrode groups are stacked so as to be spaced apart from each other, The battery cell according to the present invention has high dimensional stability and is easy to manufacture.

Meanwhile, in one specific example, the second electrode group may have a size of 90% to 110% of the first electrode group on a horizontal cross section with respect to the paper, but the size is not limited to the size, The second electrode group and the second electrode group may have the same shape on a horizontal cross section with respect to the ground. In this case, the shape of the first electrode group and the second electrode group is not particularly limited as long as it is a shape excluding a general rectangular shape.

Here, the size may be, for example, the volume or area of the electrode groups, and the shape except for the rectangular shape may be defined as atypical.

In one specific example, the atypical first electrode group and the second electrode group may be, for example, a shape including a curve or a curve, a character shape, or a graphic shape of a highly complicated geometric structure, But may be circular, elliptical, semicircular or polygonal, but is not limited thereto.

Likewise, the first opening and the second opening may be of the same shape on a horizontal section with respect to the ground, and the first opening and the second opening may be circular, elliptical, semicircular or polygonal on a horizontal cross- But are not limited to these.

In one specific example, it is preferable that the average inner diameter of the first opening is larger than the average inner diameter of the second opening including the projecting portion. Specifically, the average inner diameter of the first opening is preferably 101% 120%, and the average inner diameter of the first opening may be configured to coincide with the outer diameter of the protrusion so as to be firmly fixed to the protrusion.

In this specification, the term " average inner diameter " means that the electrode group having a structure in which a separation membrane is provided between the positive electrode and the negative electrode can be formed with openings having different inner diameters depending on the volume difference between the positive electrode and the negative electrode, The sum is calculated as an average.

In one specific example, the protrusions may protrude from 1% to 10% of the thickness of the first electrode group so as to fix the first opening of the first electrode group.

Also, in a general battery cell, the irreversible capacity can be increased due to the electrochemical reaction between the negative electrode and the positive electrode, so that the negative electrode can be set larger than the positive electrode, It is preferable that the negative electrode is formed on the negative electrode of the group.

In one specific example, the electrode tab may be mounted on one end of the first electrode group and the second electrode group so that the electrode tab protrudes from the outer surface of the electrode assembly.

On the other hand, the electrode tab may protrude into the opening of the electrode assembly. In this case, the first electrode group and the second electrode group may have an electrode tab attached to one end of the opening.

This position of the electrode tab can be set according to the internal structure of the device and the internal space utilization. For example, when some members of the device are accommodated on the inside of the opening of the electrode assembly, the electrode tabs can be set to protrude to the outer surface of the electrode assembly, and when the overall shape and size of the device is similar to the battery cell, The tabs may be set to protrude from the opening of the electrode assembly so that the outer surface of the battery cell corresponds to the inner space of the device.

In one specific example, the battery case is preferably easy to deform in correspondence with the shape of the electrode assembly having the opening, and more specifically, it may be a laminate sheet or a metal can including a resin layer and a metal layer. However, no.

The present invention also provides a method of manufacturing the battery cell. Specifically, the method comprises:

A step of punching the first electrode group into a predetermined shape and perforating the first opening;

Punching a second electrode group into a predetermined shape and punching a second opening formed with a protrusion by a punch having an outer diameter smaller than an average inner diameter of the first opening in a state where the second electrode group is positioned on the die; And

Placing the second electrode groups on the upper and lower ends of the first electrode group and then inserting the protrusions on the first aperture;

. ≪ / RTI >

The battery cell according to the present invention may be a lithium secondary battery. Generally, the lithium secondary battery includes 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 and sulfates of Li such as Li ₄ SiO ₄ -LiI-LiOH and Li ₃ PO ₄ -Li ₂ S-SiS ₂ can be used.

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

For the purpose of improving the charge-discharge characteristics and the flame retardancy, the 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 and the like 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 pack including at least two battery cells as unit cells. That is, the present invention provides a battery pack having a structure in which two or more battery cells are connected in series and / or in parallel as a unit cell, and the battery pack is used for a mobile phone, a portable computer, a smart phone, a tablet PC, a smart pad, (Light Electronic Vehicle), an electric vehicle, a hybrid 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, since the battery cell according to the present invention is formed with an opening in a predetermined shape, a part of the device that is bent or indented can be accommodated inside the opening, The present invention can be applied not only to various device types but also to accommodate other members of the device such as an electric circuit or a washer through the opening of the battery cell, so that the utilization of the internal space of the device is very high.

Also, the battery cell has a structure in which the electrode assemblies are stacked in such a manner that the first openings are mounted on the upwardly or downwardly extending protrusions formed in the second openings, and it is easy to stack the electrode groups without a separate fixing member or manual operation As a result, the present invention can provide a battery cell having high dimensional stability.

1 is a schematic view of a conventional battery cell;
2 is a schematic view of an electrode assembly having an opening according to the present invention and a battery cell including the same;
3 is a perspective view of the electrode assemblies constituting the electrode assembly of FIG. 2;
FIG. 4 is an enlarged schematic vertical section of the electrode groups of FIG. 3; FIG.
5 is a vertical cross-sectional view of the electrode assembly in which the electrode groups of FIG. 4 are stacked.

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. In particular, the shape of the components specified in the embodiment, for example, the shape of the circle is arbitrarily set, and as described above, the battery cell of the present invention can be applied to various forms other than a general rectangular shape. Of course. Therefore, in the following description, the definition of the atypical battery cell is set to be composed of the circular components, and the structure of the battery cell will be described in detail with reference to it.

First, the battery cell according to the present invention can be described with reference to a schematic view as shown in FIG.

2, the battery cell 100 includes an electrode assembly 101 in which an opening 104 is perforated, a positive electrode tab 113 and a negative electrode tab 114 protruding to one side of the electrode assembly 101, And a pouch-shaped battery case 102 having a shape corresponding to the outer shape of the electrode assembly 101.

The electrode assembly 101 has a circular shape on the horizontal cross section with respect to the ground as a whole and also has a circular opening 104 penetrating the center of the electrode assembly 101 on the horizontal cross section with respect to the ground, An insulating tape 103 is attached to the inner wall of the opening of the housing 101.

The pouch-shaped battery case 102 includes a housing 102a for housing the electrode assembly 101 and a sealing cover portion 102b for sealing the electrode assembly 101 by being thermally fused to the upper end of the housing portion 102a have.

The electrode assembly 101 has two electrode leads (not shown) electrically connected to the positive and negative electrode tabs 113 and 114 and is connected to the receiving portion 102a of the pouch- And then sealed with the sealing cover portion 102b.

The electrode assembly 101 has a structure in which a plurality of electrode groups in which a circular opening 104 is formed in a plane are stacked together with a separation membrane. Hereinafter, the structure of the electrode assembly will be described in detail with reference to FIGS. 3 to 5 something to do.

In this regard, FIG. 3 schematically shows electrode groups constituting the electrode assembly of FIG. 2, FIG. 4 schematically shows a vertical sectional view of the electrode groups of FIG. 3, and FIG. And electrode groups are stacked.

Referring to these drawings, the electrode assembly 101 includes a first electrode group 112, two second electrode groups 110a and 110b, and two separators 111 interposed between the electrode groups, .

The first electrode group 112 and the second electrode groups 110a and 110b have a structure in which a separator is formed between the anode and the cathode and between the anode and the cathode. More specifically, the separator 201 And a negative electrode group 202 made of a negative electrode is formed on the separator 201. The negative electrode group 200 is formed of a positive electrode, The total diameter R _n of the negative electrode group 202 formed in one electrode group is longer than the total diameter R _p of the positive electrode group 200, Is larger than the total volume of the anode group (200).

The first electrode group 112 has a first opening 130 formed at the center thereof with respect to a vertical cross section and a horizontal cross section with respect to the ground. The second electrode groups 110a and 110b have vertical cross sections and horizontal And the second openings 120a and 120b are perforated at the center portion thereof with respect to the cross section.

The separators are formed to be longer than the total diameter of the negative electrode group 202 of the first electrode group 112 and the negative electrode group 202 of the second electrode group 110a and 110b, And has an inner diameter smaller than the opening 130 and the second openings 120a and 120b.

The second openings 120a and 120b are formed with protrusions 210 protruding upward from the opening ends of the negative electrode group 202. The protrusions 210 are formed in the first openings 130 such that the average inner diameter R ₁₎ and consists of the same outer diameter (Z _1), the second apertures (average diameter (R ₂₎ of the 120a, 120b) is made smaller than the average inside diameter (R ₁₎ of the first opening 130.

The average inner diameters of the first opening 130 and the second openings 120a and 120b are the same as those of the first electrode group 112 and the cathode group 202 and the anode group 200 of the second electrode group 110a and 110b, Is the average value of the sum of the inner diameters of the openings of the openings. The opening diameters of the positive electrode groups 202 of the first electrode group 112 and the second electrode group 110a and 110b are all the same as the outside diameter of the protrusion 210. [

Accordingly, the first opening 130 or the second openings 120a and 120b include the anode group 200 that can be mounted on the protrusion, and the second electrode groups 110a and 110b including the protrusions The electrode assembly 101 can be completed by various lamination methods. In addition, since the openings of the electrode groups are fixed by the projecting portions 210, the electrode groups can be stacked easily and without any additional members with high dimensional stability.

4 and 5, the protrusions 210 of the second openings 120a and 120b are inserted into the first opening 130 together with the openings of the separator, 5, the second electrode group 110a, the separation layer 111, the second electrode group 110b, and the second electrode group 110b are inserted into the openings of the anode group 200 of the electrode group located at the upper end of the stack. A separator and a first electrode group 112 are stacked in this order to form an electrode assembly 101.

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 (21)

A first electrode group having a structure in which a separator is interposed between the anode and the cathode; And a second electrode group mounted in a state where a separation membrane is interposed between the upper end and / or the lower end of the stack of the first electrode group, wherein the electrode assembly is built in a battery case,
Wherein a first opening is drilled in the center of the first electrode group, a second opening is drilled in the center of the second electrode group, the first opening and the second opening are in communication with each other, A protruding portion extending upward or downward is formed, a first opening is mounted on the protruding portion,
Wherein a laminated upper end of the second electrode group is mounted on the lower end of the stack of the first electrode group in a state in which the upward protruding portion of the second opening is inserted into the first opening or a downward protruding portion of the second opening is inserted And the second electrode group is mounted on the upper end of the stack of the first electrode group. The battery cell according to claim 1, wherein the electrode assembly includes one or more first electrode groups and one or two second electrode groups. The battery cell according to claim 1, wherein the second electrode group has a horizontal cross section with respect to the ground, and is 90% to 110% of the size of the first electrode group. The battery cell according to claim 1, wherein an average inner diameter of the first opening is in a range of 101% to 120% of an average inner diameter of the second opening. The battery cell according to claim 1, wherein the first electrode group and the second electrode group have the same shape in horizontal cross section with respect to the ground. The battery cell according to claim 5, wherein the first electrode group and the second electrode group are circular, elliptical, semicircular, or polygonal in horizontal cross section with respect to the ground. The battery cell according to claim 1, wherein the first opening and the second opening have the same shape on a horizontal cross section with respect to the ground. The battery cell according to claim 7, wherein the first opening and the second opening are circular, elliptical, semicircular or polygonal on a horizontal cross section with respect to the ground. delete delete The battery cell according to claim 1, wherein an average inner diameter of the first opening coincides with an average outer diameter of the protrusion. The battery cell according to claim 1, wherein the second electrode group is an electrode group having a structure in which a separator is interposed between an anode, a cathode, or an anode and a cathode. The battery cell according to claim 1, wherein the protruding portion protrudes at a height of 1% to 10% of a thickness of the first electrode group. The battery cell according to claim 1, wherein the projecting portion is formed by a cathode of the second electrode group. The battery cell according to claim 1, wherein the battery case comprises a laminate sheet or a metal can including a resin layer and a metal layer. The battery cell according to claim 1, wherein the first electrode group and the second electrode group are each provided with an electrode tab at one end thereof. The battery cell according to claim 1, wherein the first electrode group and the second electrode group are each provided with an electrode tab at one end of the opening. A method of manufacturing a battery cell according to claim 1,
A step of punching the first electrode group into a predetermined shape and perforating the first opening;
Punching the second electrode group into a predetermined shape and punching a second opening formed with a protrusion with a punch having an outer diameter smaller than the inner diameter of the second opening in a state in which the second electrode group is positioned on the die; And
Placing the second electrode groups on the upper and lower ends of the first electrode group and then inserting the protrusions on the first aperture;
≪ / RTI > A battery pack comprising at least two battery cells according to any one of claims 1 to 8 and 11 to 17 as unit cells. A device comprising the battery pack according to claim 19 as a power source. 21. The method of claim 20, 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, ≪ / RTI > device.

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