KR101650034B1 - Battery Cell Having Round-typed Outer Surface - Google Patents

Abstract

The present invention relates to an electrode assembly having a structure in which electrode units having at least two different areas are stacked with a separator interposed therebetween, the electrode assembly having an outer circumferential surface of the electrode units in a round shape on a vertical section with respect to the paper surface; An electrolyte solution impregnated into the electrode assembly; And a battery case in which the electrode assembly is embedded.

Description

(Battery Cell Having Round-typed Outer Surface)

The present invention relates to a battery cell having a curved outer surface, and more particularly, to an electrode assembly having a structure in which electrode units having at least two different areas are stacked with a separator interposed therebetween, An electrode assembly having a round shape in cross section; An electrolyte solution impregnated into the electrode assembly; And a battery case in which the electrode assembly is embedded.

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 separation membrane interposed therebetween. The electrode assembly 30 has a stacked or stacked / folded 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. 1, a plurality of positive electrode taps 40 and a plurality of negative electrode tabs 50 may be coupled to the electrode leads 60 and 70. In the stacked electrode assembly 30, The upper end 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 manufacture electrodes of different sizes from the battery cells of different sizes, it is required that the battery cells have very precise dimensional stability when the electrodes are stacked. In particular, It may not match. 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 is 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.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided an electrode assembly in which electrode units having at least two different areas are stacked with a separator interposed therebetween, round electrode assembly; An electrolyte solution impregnated into the electrode assembly; And a battery case in which the electrode assembly is embedded.

Therefore, the battery cell according to the present invention is applicable to a shape of a bent or curved device, since the outer surface of the electrode unit constituting the electrode assembly is formed in a round shape on a vertical section with respect to the paper surface, It is possible to manufacture battery cells having various capacities and sizes based on the same specific structure, thereby maximizing utilization of the space inside the device.

In this regard, the battery cell can set various lamination structures of the electrode units according to shape, area, thickness, etc. of the electrode units in consideration of the shape of the device and the battery capacity required for the device.

First, as a specific example of the area of the electrode unit, the horizontal cross-sectional area of the electrode units may be stacked in the order of sequentially decreasing with respect to the stacking direction in the electrode assembly, and conversely, have. In this case, the degree of increase or decrease in the horizontal cross-sectional area of the electrode units may be set in the range of 90 to 110% relative to the adjacent electrode unit.

If the horizontal cross-sectional area of the electrode units deviates from the above range, excessive electrode density deviation may occur between the electrode units, which may degrade the performance of the battery cells.

The thickness of the electrode units may coincide with the diameter of the round shape formed on the outer circumferential surface of the electrode unit, and the diameter of the round shape may be 90 to 110% of the round diameter of the adjacent electrode unit Can be sequentially increased or decreased in the range.

On the other hand, the shapes of the electrode units are not particularly limited as long as they are in a shape in which uniformity of the electrode units is felt, except for a general rectangular shape.

Here, a shape other than a rectangle may be defined as an irregular shape. Such irregular electrode units may be, for example, a shape including a curve or a curvature, a character shape, or a shape of a highly complicated geometric structure, But may be circular, elliptical, semicircular, or polygonal on the horizontal plane of the electrode units, but is not limited thereto.

In one specific example, the electrode units may include a first electrode disposed at the lowermost end of the electrode assembly, a second electrode stacked on the upper surface of the first electrode, and a third electrode mounted on the upper surface of the second electrode. have.

That is, the electrode assembly is a stacked body of electrode units which are the first electrode, the second electrode and the third electrode, and may be laminated in various forms by modifying the lamination structure of the first electrode, the second electrode and the third electrode . Specific examples thereof will be described in detail below.

First, as a first specific example of the lamination structure, the first electrode, the second electrode, and the third electrode are formed such that the central axes, which are imaginary lines passing vertically through the center of the horizontal plane of each of the first to third electrodes, As shown in FIG.

The electrode units made of such a laminated structure have a shape in which the central axis of the electrode unit and the vertical penetration axis of the electrode assembly coincide with each other, and the right and left sides of the vertical direction of the electrode assembly are symmetrical to each other.

As a second example of the laminated structure, the first electrode, the second electrode, and the third electrode may be laminated in such a shape that their central axes are inclined with respect to the vertical axis with respect to the paper, And can be stacked in an inclined shape at an angle of view.

Further, as a third example of the laminated structure, the first electrode, the second electrode and the third electrode may be laminated in an arrangement in which one side of them is aligned. The laminated structure may have a step formed on the opposed surface of the one side surface, and the stepped shape may be a form of decreasing or increasing in size in the lamination direction.

The first electrode, the second electrode, and the third electrode may have openings of the same shape, and the openings may be circular or elliptical with respect to a horizontal cross section with respect to the ground.

The apertured electrodes may be formed by applying the above-described lamination structures to an electrode assembly having apertures drilled therein.

In this regard, the openings may be in communication with each other in a laminated structure of the first electrode, the second electrode and the third electrode, wherein the openings are formed in the first electrode, the second electrode, . ≪ / RTI >

Specifically, the openings may be perforated on the first electrode, the second electrode, and the third electrode at positions where their central axes coincide with the central axis of the third electrode.

That is, the opening is perforated on the first electrode, the second electrode, and the third electrode with respect to the central axis of the third electrode. Even if the above-described three stacked structures are applied to the electrode units, The openings can be laminated to the electrode assembly in a mutually communicating state regardless of the stacking position of the two electrodes.

On the other hand, protrusions may be formed on the openings in order to prevent the positions of the openings from being inconsistent or being stacked apart from each other in the process of stacking the electrodes so that the openings communicate with each other.

In one specific example, the opening of the second electrode may be formed with an upward protrusion and a downward protrusion extending from an end of the opening, so that the upward protrusion is an opening of the third electrode, The opening can be fixed.

At this time, the upward projecting portion formed in the opening of the second electrode coincides with the opening inner diameter of the third electrode so that the opening of the projecting portion and the electrode can be fixed firmly, and the downward projecting portion coincides with the opening inner diameter of the first electrode ≪ / RTI >

The downward protruding portion and the upward protruding portion of the above-described structure mount and fix the first electrode and the third electrode, which are stacked on the lower and upper ends of the second electrode, respectively. The first electrode, the second electrode, It is possible to prevent the electrodes from being laminated so as to be finely spaced apart or to be stacked in a state where the positions of the openings are not coincident with each other.

That is, by including the upward protruding portion and the downward protruding portion, it is possible to stack the electrodes with high dimensional stability without a separate fixing member or manual operation in the process of stacking the electrodes.

The first electrode, the second electrode, and the third electrode are laminated in such a manner that, for example, the first electrode and the second electrode are stacked in the state where the downward projecting portion is inserted into the opening of the first electrode, The second electrode and the third electrode may be structured such that the upward projecting portion is inserted into the opening of the third electrode and the stacked upper end of the second electrode is mounted at the lower end of the stack of the third electrode Lt; / RTI >

Meanwhile, in one specific example, the first electrode, the second electrode, and the second electrode may have electrode tabs at one end thereof 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 electrode tab may be mounted at one end of the openings of the first electrode, the second electrode and the third electrode.

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 units, the electrode taps may be set to protrude to the outer surface of the electrode units, and when the overall shape and size of the device is similar to the battery cell, The tabs may be configured to protrude from the opening of the electrode units 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.

Meanwhile, the battery cell according to the present invention may be a lithium secondary battery. In general, the lithium secondary battery comprises 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 module including at least two battery cells as unit cells, and a battery pack including one or more battery modules. These battery packs can be used in devices such as mobile phones, portable computers, smart phones, tablet PCs, smart pads, netbooks, light electronic vehicles (LEVs), electric vehicles, hybrid electric vehicles, plug- Can be used.

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, the battery cell according to the present invention can be applied to the shape of a bent or curved device by forming the outer peripheral surface of the electrode unit constituting the electrode assembly in a round shape on the vertical cross section with respect to the paper surface , It is possible to manufacture a battery cell having various capacities and sizes based on the specific structure as described above, thereby maximizing the utilization of the space inside the device.

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 units constituting the electrode assembly of FIG. 2;
4 is an enlarged schematic view of a vertical section of the electrode units of FIG. 3;
5 is a cross-sectional view of an electrode assembly in which one side of the electrode units is stacked in an aligned arrangement;
6 is a cross-sectional view of the electrode assembly in which the central axes of the electrode units are stacked in a shape inclined with respect to the vertical axis with respect to the paper surface.

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 is circular in a horizontal section with respect to the ground and has a circular opening 104 passing through the center of the electrode assembly 101 on a horizontal cross section with respect to the ground, An insulating tape 103 is attached.

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 102a has two electrode leads (not shown) electrically connected to the positive and negative electrodes tabs 113 and 114 exposed to the outside, 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 electrodes having a circular opening 104 formed in a plane are laminated together with a separation membrane. Hereinafter, the structure of the electrode assembly will be described in detail with reference to FIGS. 3 and 4 will be.

In this regard, FIG. 3 schematically shows electrodes constituting the electrode assembly of FIG. 2, and FIG. 4 schematically shows a vertical section of the electrode groups of FIG. 3.

Referring to these figures, the electrode assembly 101 includes a first electrode 110c, a second electrode 110b, and a third electrode 110a, and two separators 111 And the horizontal cross-sectional area of the electrodes 110a, 110b and 110c is sequentially decreased in the stacking direction of the electrode assembly 101. In addition, More specifically, the first electrode 110c, the second electrode 110b, and the third electrode 110c of FIG. 4 are stacked in such a manner that their center axes C ₁ are aligned with each other.

The outer diameter of the first electrode 110c, the second electrode 110b and the third electrode 110a are rounded and the round diameter R ₁ of the first electrode 110c is larger than the diameter of the second electrode 110b ) round diameter (R ₂₎ larger round diameter of the second electrode (110b) (R ₂₎ is a round diameter (R ₃₎ which is larger than the configuration bar, the electrode assembly (101 of the third electrode (110a)) of (R ₁ , R ₂ , R ₃ ) of the electrodes 110a, 110b and 110c are sequentially decreased in the stacking direction.

The electrode assembly 101 is formed with openings 130, 130 ', and 140 on the first electrode, the second electrode, and the third electrode at positions corresponding to the central axis C _{1 of} the third electrode, The openings 130, 130 ', and 140 are in communication with each other.

The opening 140 of the second electrode has an upward protruding portion 140a protruding upward from its end and a downward protruding portion 140b protruding downwardly. Is inserted into the opening 130 'of the electrode 110a and the downward protrusion 140b is inserted into the opening 130 of the first electrode 110c.

The upward protrusion 140a of the opening 140 of the second electrode 110b is formed to have the same outer diameter as the inner diameter of the opening 130 'of the third electrode 110a, The protrusion 140b has an outer diameter equal to the inner diameter of the opening 130 of the first electrode 110c.

Accordingly, the openings 130 and 130 'of the first electrode 110c and the third electrode 110a are mounted and fixed to the downward and upward protrusions 140b and 140a formed in the openings of the second electrode 110b, The electrodes 110a, 110b and 110c can be laminated with ease and high dimensional stability without a separate member.

5 is a cross-sectional view schematically showing an electrode assembly showing another stacked structure of the electrode groups.

5, one side of the first electrode 201c, the second electrode 201b, and the third electrode 210a forms an imaginary axis C ₂ , and it is laminated in the state, the vertical through the electrode assembly 201 and the third electrode (210a) a first electrode (210c), the second electrode (210b to corresponding to the center axis (C ₃₎ a position in agreement with the center of And the openings of the third electrode 210a are communicated with each other. On the other hand, a step 250 is formed on the opposing surface with respect to the side surface of the electrode assembly 201 on which the hypothetical axis C ₂ is formed.

6 schematically shows an electrode assembly in which the central axes of the electrode units are stacked in a shape inclined with respect to the vertical axis with respect to the paper surface.

6, the electrode assembly 301, the vertical axis a first electrode on the basis of the (C _4), (310c) passing through the center (a) of the third electrode (310a) vertically, a second electrode (310b) and the center of the third electrode (310a), and an opening is perforated in a state that is mutually communicated with the vertical shaft (C ₄₎ an imaginary line (L) a second electrode (310b) of the tilted by the slope (d) from the first electrode 310c, the second electrode 310b and the third electrode 310a are stacked so as to coincide with the center c of the first electrode 310b and the first electrode 310b.

As a result, as shown in FIGS. 2 to 6, the battery cells according to the present invention are formed by rounding the outer circumferential surfaces of the electrode units and stacking the electrodes of different sizes in various manners, It is possible to easily mount a cell in which a conventional battery cell is difficult to be mounted and also to mount a cell having a larger capacity in a limited space according to the internal structure of the device, Can be maximized.

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 (22)

An electrode assembly having a structure in which at least two electrode units having different areas are stacked with a separator interposed therebetween, the electrode assembly having an electrode assembly in which an outer circumferential surface of the electrode units is round in a vertical section with respect to the sheet surface;
An electrolyte solution impregnated into the electrode assembly; And
A battery case in which the electrode assembly is embedded;
Lt; / RTI >
The electrode units include a first electrode disposed at the lowermost end of the electrode assembly, a second electrode stacked on the upper surface of the first electrode, and a third electrode mounted on the upper surface of the second electrode,
The first electrode, the second electrode, and the third electrode have apertures of the same shape,
The openings are perforated on the first electrode, the second electrode and the third electrode at positions where their central axes coincide with the central axis of the third electrode,
Wherein an opening of the second electrode is formed with an upward protruding portion and a downward protruding portion extending from an end of the opening,
Wherein an upward protrusion of the second electrode coincides with an opening inner diameter of the third electrode, and a downward protrusion of the second electrode coincides with an opening inner diameter of the first electrode. The battery cell according to claim 1, wherein the horizontal cross-sectional area of the electrode units is a structure that decreases or increases sequentially with reference to the stacking direction in the electrode assembly. The battery cell according to claim 1, wherein the round shape of the electrode units is a structure in which the diameter sequentially increases or decreases based on a stacking direction in the electrode assembly. The battery cell according to claim 1, wherein the electrode units are circular or elliptical on a horizontal plane. delete The battery cell according to claim 1, wherein the first electrode, the second electrode, and the third electrode are stacked in an arrangement in which their central axes coincide. The battery cell according to claim 1, wherein the first electrode, the second electrode, and the third electrode are laminated in an arrangement in which one side of the first electrode, the second electrode, and the third electrode coincide with each other. The battery cell according to claim 1, wherein the first electrode, the second electrode, and the third electrode are laminated in such a shape that their central axes are inclined with respect to a vertical axis with respect to the ground. delete delete 10. The battery cell according to claim 9, wherein an opening of the second electrode is formed with an upward protruding portion and a downward protruding portion extending from an end of the opening. delete delete delete The battery cell according to claim 1, wherein the openings are circular or elliptical with respect to a horizontal cross section with respect to the ground. The battery cell according to claim 1, wherein an electrode tab is mounted at one end of the openings. The battery cell according to claim 1, wherein the first electrode, the second electrode, and the third electrode have electrode tabs at one end thereof. 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. A battery module comprising at least two battery cells according to any one of claims 1 to 4, 6 to 8, and 14 to 17 as unit cells. A battery pack comprising the battery module according to claim 18. 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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