KR20150035079A - Battery Cell Having Separation Film of Suppressed Thermal Shrinkage - Google Patents

Abstract

Provided is a battery cell having suppressed thermal shrinkage of separation films, wherein an electrode assembly including a cathode, anode, unit cells with a stacked structure composing of separation membranes interposed between the cathode and the anode, and a separation film for continuously winding the unit cells is mounted onto a storage unit of a battery case; a cathode tab and anode tab protrude from at least one surface of the outer peripheral surfaces of the cathode and anode in the unit cells; the separation membranes protrude longer than the cathode and anode in the unit cells to form the separation membrane extended parts, and the separation films protrude longer than the separation membranes of the unit cells to form the separation film extended parts; and the separation film extended parts are connected to each other by heat fusion in at least one part of the outer surface of the electrode assembly having protruded cathode tab and anode tab of the unit cells and an opposite surface of the outer surface.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a battery cell having suppressed thermal contraction of a separator,

The present invention provides an electrode assembly including a positive electrode, a negative electrode, a unit cell having a laminated structure composed of a separator interposed between the positive and negative electrodes, and a separation film for continuously winding the unit cells, Have; A positive electrode tab and a negative electrode tab protruding from at least one surface of the outer surface of the positive electrode and the negative electrode of the unit cells; The separator may protrude longer than the positive electrode and the negative electrode to form a separation membrane elongation part, wherein the separation membrane protrudes to a length longer than the separation membrane of the unit cells to form a separation membrane extension part; Wherein the separation film extension portion is mutually coupled to the outer surface of the electrode assembly protruding from the positive electrode tab and the negative electrode tab of the unit cells and at least a part of the opposing surface of the outer electrode by heat fusion.

In recent years, the demand for environmentally friendly alternative energy sources has become an indispensable factor for the future, as the increase in the price of energy sources due to depletion of fossil fuels and the interest in environmental pollution are amplified. Various researches on power generation technologies such as nuclear power, solar power, wind power, and tidal power have been continuing, and electric power storage devices for more efficient use of such generated energy have also been attracting much attention.

Particularly, as technology development and demand for mobile devices are increasing, the demand for batteries as energy sources is rapidly increasing, and accordingly, a lot of researches on batteries that can meet various demands have been conducted.

Typically, in terms of the shape of a battery, there is a high demand for a prismatic secondary battery and a pouch-type secondary battery which can be applied to products such as mobile phones with a small thickness, and has advantages such as high energy density, discharge voltage, There is a high demand for lithium secondary batteries such as lithium ion batteries and lithium ion polymer batteries.

The secondary battery includes a cylindrical battery and a prismatic battery in which the electrode assembly is housed in a cylindrical or rectangular metal can according to the shape of the battery case, and a pouch type battery in which the electrode assembly is housed in a pouch-shaped case of an aluminum laminate sheet .

In particular, in recent years, a pouch-shaped battery having a structure in which a stacked or stacked / folded electrode assembly is embedded in a pouch-shaped battery case of an aluminum laminate sheet has attracted much attention due to low manufacturing cost, small weight, And its usage is gradually increasing.

Also, the secondary battery is classified according to the structure of the electrode assembly having the structure in which the anode, the cathode, and the separator interposed between the anode and the cathode are laminated. Typically, the long battery- A stacked (stacked) electrode assembly in which a plurality of positive electrodes and negative electrodes cut in a predetermined size unit are sequentially stacked with a separator interposed therebetween, the jelly-roll type (wound type) electrode assembly having a structure in which a separator is interposed; In recent years, in order to solve the problems of the jelly-roll type electrode assembly and the stack type electrode assembly, an electrode assembly having an advanced structure, which is a combination of the jelly-roll type and the stack type, Bi-cells or full cells, which are stacked with a separator interposed between an anode and a cathode, are sequentially wound on a separator film Stacked / folded electrode assemblies have been developed.

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

One of the problems of safety is that the internal short circuit due to shrinkage or breakage of the separator which occurs when the battery is exposed to high temperature is very serious.

In general, a porous polymer film such as polyethylene or polypropylene is used as a separator. Such a separator is advantageous in that it is inexpensive and has excellent chemical resistance and is suitable for operation of a battery, but is liable to shrink in a high temperature environment.

FIG. 1 schematically illustrates a typical structure of a conventional stack / folding type electrode assembly.

1, the electrode assembly 100 includes first unit cells 102 and 104 having a structure in which a cathode is disposed between positive electrodes and a separator is disposed between the positive and negative electrodes, and an anode is disposed between the cathodes , And a combination of second unit cells (101, 103, 105) having a structure in which a separation membrane is interposed between the anode and the cathode.

The separation film 106 interposed between the first unit cells 102 and 104 and the second unit cells 101 and 103 and 105 of the electrode assembly 100 is a first The electrode assembly includes the first unit cells 102 and 104 and the second unit cells 102 and 104 on the separation film 106. The first unit cells 102 and 104 and the second unit cells 101 and 103 and 105, Two unit cells 101, 103, and 105 are arranged and the separation film 106 is wound.

Generally, in the case of such a stack / folding type electrode assembly, a separation film interposed between the anode and the cathode of the unit cell and the separation film interposed between the unit cells is shrunk between the interfaces of the electrodes at both ends thereof in a high- It is easy to cause a short circuit.

When the separation membrane and the separation membrane are designed to be larger than the anode and the cathode in order to prevent the above problems, the separator film protruded from the outer circumferential surface of the anode and the cathode, and the extended portion of the separation film, It is possible to reduce the insertion property of the electrode assembly with respect to the electrode assembly.

Therefore, there is a high need for a technique capable of fundamentally solving such problems.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems of the prior art and the technical problems required from the past, and it is an object of the present invention to provide a separator for separating an electrode assembly from an electrode assembly, It is an object of the present invention to provide a battery cell in which the heat shrinkability of the separation membrane and / or the separation film is suppressed.

It is a further object of the present invention to provide a separator in which the extension of the separation film is mutually bonded to the outer surface of the electrode assembly protruding from the electrode tabs of the unit cells and the outer surface of the outer surface by thermal fusion only, And to provide a battery cell having a structure capable of improving the insertion property of the electrode assembly with respect to the battery case and preventing impregnability of the electrolyte solution from deteriorating.

According to an aspect of the present invention, there is provided a battery cell comprising:

An electrode assembly including a positive electrode, a negative electrode, a unit cell having a laminated structure composed of a separator interposed between the positive electrode and the negative electrode, and a separator film for continuously winding the unit cells are mounted on a receiving portion of the battery case;

A positive electrode tab and a negative electrode tab protruding from at least one surface of the outer surface of the positive electrode and the negative electrode of the unit cells;

The separator may protrude longer than the positive electrode and the negative electrode to form a separation membrane elongation part, wherein the separation membrane protrudes to a length longer than the separation membrane of the unit cells to form a separation membrane extension part;

Wherein the separation film extension portion is composed of a structure in which the positive electrode tab and the negative electrode tab of the unit cells are mutually coupled by thermal fusion at an outer surface of the electrode assembly protruding and at least a part of the opposing surface of the outer surface.

As described above, the battery cell according to the present invention is configured such that the separation film extension portion of the electrode assembly is mutually coupled at the outer surface of the electrode assembly protruding the electrode tab and at least a part of the opposite surface of the outer surface, It is possible to suppress the heat shrinkage of the thermoplastic resin.

Further, the separation film extension portion is mutually bonded to the outer surface of the electrode assembly protruding from the electrode tabs of the unit cells and the outer surface of the outer surface by heat fusion, And the effect of preventing impregnability of the electrolytic solution from deteriorating is exhibited.

In one specific example, the electrode assembly may have a structure in which the unit cells are sequentially wound with the unit cells positioned on a long length of the separation film.

In other words, the electrode assembly of the battery cell according to the present invention includes unit cells of a laminated structure composed of an anode, a cathode, and a separator interposed between the anode and the cathode, Wherein the width of the separation film is the size of the outer circumferential surface of the separation film in the direction parallel to the electrode tab projecting direction of the unit cells positioned on the separation film, Is the size of the outer circumferential surface of the separation film in the direction perpendicular to the width.

Therefore, the electrode assembly of the battery cell according to the present invention is an advanced electrode assembly in which the jelly-roll type electrode assembly and the stacked electrode assembly are mixed, and the problems of the conventional jelly- Can be solved.

In this case, the unit cells of the electrode assembly may have a structure in which the outermost electrodes have the same polarity, or a structure in which the outermost electrodes have different polarities from each other.

Specifically, the unit cell has a structure in which an anode, a separator, a cathode, a separator, and a cathode are stacked in this order. Thus, a cathode having the same polarity may be positioned on both sides of the unit cell, or a cathode, a separator, A structure in which a cathode having the same polarity is located on both sides of the unit cell may be used.

On the other hand, the unit cell may have a structure in which an anode, a separator, and a cathode are stacked in this order, and the anode and the cathode having different polarities may be positioned on both sides of the unit cell.

However, the structure of the unit cell is not limited to this, and may be a structure in which a plurality of positive electrodes, a separator, and a negative electrode are laminated, and the outermost electrodes have the same polarity or different lamination structures, It is not.

In another specific example, the unit cells may have a structure in which the positive electrode tab and the negative electrode tab protrude from the same surface on the outer surface of the unit cells, but the present invention is not limited thereto, Or may be a structure that protrudes on one surface and the other surface facing each other on the outer surface of the cells.

In other words, the unit cells may have a structure in which the positive electrode tab and the negative electrode tab protrude in the same direction or protrude in directions opposite to each other, The positive electrode tab and the negative electrode tab may be coupled to each other at least in part except for the protruded portions of the outer surface of the assembly and the opposite surfaces of the outer surface.

In the unit cells constituting the battery cell according to the present invention, the separation membrane is protruded by a length longer than the length of the anode and the cathode to form a separation membrane extension portion. The separation membrane for winding up the unit cells protrudes longer than the separation membrane of the unit cells The length of the separation membrane elongation part may be 1 to 20% of the length of the anode or the cathode, and the length of the separation membrane extension part may be 2 to 30% .

Therefore, only the separation film extension portions protruding longer than the separation membrane are mutually bonded, so that the heat shrinkability of the separation film can be suppressed under a high temperature condition and the high temperature safety can be improved.

The term of the length indicates the size of the outer circumferential surface of the anode, the cathode, the separator, and the separator film which are parallel to the protruding direction of the positive electrode tab and the negative electrode tab in the unit cells.

In addition, the extended portions of the separation films of the electrode assembly constituting the battery cell according to the present invention are mutually coupled by heat fusion. The heat fusion may be performed for 1 to 10 seconds at a temperature in the range of 50 to 120 degrees Celsius, May be performed for 2 to 4 seconds in the range of 50 to 60 degrees.

If the thermal bonding temperature is less than 50 deg. C or the thermal bonding time is less than 1 second, the desired bonding force of the separation membrane and the separation film can not be exerted. If the thermal bonding temperature exceeds 120 deg. If it exceeds 10 seconds, it may lead to excessive shrinkage and damage of the separation membrane and the separation film having weak characteristics at high temperature.

In one specific example, the separation film extension portion may be a structure in which the outer surface of the electrode assembly protruding from the positive electrode tab and the negative electrode tab of the unit cells and the outer surface of the outer surface are mutually coupled by thermal fusion.

More specifically, on the outer surface of the electrode assembly protruding from the positive electrode tab and the negative electrode tab of the unit cells and on the opposing surface of the outer surface, the outer surface of the electrode assembly excluding the projecting portions of the positive electrode tab and the negative electrode tab, When the separating film extension portion is bonded by heat fusion, impregnation of the electrolyte solution into the electrode assembly in the manufacturing process of the battery cell can be reduced.

Therefore, in the battery cell according to the present invention, the separation film extension portion is mutually coupled to the outer surface of the electrode assembly protruding from the positive electrode tab and the negative electrode tab of the unit cells and the outer surface of the outer surface by heat fusion, It is possible to provide a space that can be impregnated, thereby preventing impregnability of the electrolyte solution with respect to the electrode assembly from lowering in the manufacturing process of the battery cell.

In this case, the heat-sealed outer circumferential surface may be 10 to 50% larger in area from the outer peripheral end to the outer peripheral end based on the minor axis width size of the outer surface or the opposite surface of the electrode assembly protruding from the positive electrode tab and the negative electrode tab of the unit cells .

The outer circumferential surface may be 10 to 50% larger in area from the outer circumferential end to the outer circumferential end of the outer surface or the opposite surface of the electrode assembly protruding from the positive and negative electrode tabs of the unit cells.

If the size of the thermally fused outer peripheral surface is out of the above range and is less than 10% in the minor axis and the major axis direction from the outer peripheral end, the effect of suppressing the heat shrinkage of the desired separation film and / or separation film can not be exhibited, , The impregnation property of the electrolytic solution can be lowered.

In another specific example, at least a part of the separation film extension portion may have a structure in which the electrode tabs and the anode tabs of the unit cells protrude from the outer surface of the electrode assembly and the outer surface of the separator extends to the separator extension portion.

Therefore, the extending portion of the separating film and the extending portion of the separating film are combined together, and the separating film and the separating film are partly integrated, so that the heat shrinkability of the separating film and the separating film can be more stably suppressed.

In this case, the separation membrane elongation part and the separation film extension part may be bonded by heat fusion or bonded by an adhesive, but the present invention is not limited thereto.

In general, the separator is made of an insulating thin film having high ion permeability and mechanical strength. 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 separator and the separator of the battery cell according to the present invention can be made of the same material and have high ion permeability and mechanical strength and can be bonded by heat fusion at a desired temperature or can be easily bonded by an adhesive , And is not particularly limited.

Meanwhile, the battery case of the battery cell according to the present invention may be formed of a laminate sheet including a resin layer and a metal layer.

The thermal fusion of the separation film extension may be performed before inserting the electrode assembly into the battery case so as to improve the insertion property of the electrode assembly into the battery case.

The battery cell according to the present invention is not particularly limited as long as it has the above-described structure. Specific examples thereof include a lithium ion battery having advantages such as high energy density, discharge voltage, and output stability, a lithium ion polymer battery And the like.

The configuration, structure, and manufacturing method of the battery cell including the lithium secondary battery are well known in the art, and a detailed description thereof will be omitted in this specification.

The present invention provides a device comprising the battery cell, the device comprising a cell phone, a tablet computer, a notebook computer, a power tool, an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, Lt; / RTI >

Such devices or devices are well known in the art, so a detailed description thereof will be omitted herein.

As described above, the battery cell according to the present invention is configured such that the separation membrane and / or the separation film extension part of the electrode assembly are mutually coupled at the outer surface of the electrode assembly protruding the electrode tab and at least a part of the opposite surface of the outer surface , The heat shrinkability of the separator and / or the separator film is suppressed under a high temperature condition, the internal short circuit can be prevented and the safety can be improved, and the separation film extension portion can be formed on the outer surface of the electrode assembly protruding from the electrode tabs of the unit cells, The insertion of the electrode assembly into the battery case is improved in the manufacturing process of the battery cell and the impregnability of the electrolyte solution can be prevented from deteriorating.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view schematically showing a general structure of a conventional stack / folding type electrode assembly; FIG.
2 is a schematic view showing a structure of unit cells constituting an electrode assembly of a battery cell according to an embodiment of the present invention;
3 is a schematic view illustrating a method of forming an electrode assembly of a battery cell according to an embodiment of the present invention;
4 is a schematic view schematically showing a structure of a separation film of an electrode assembly constituting a battery cell according to an embodiment of the present invention before heat fusion is performed;
5 is a partial schematic view schematically showing a laminated structure viewed from the 'c direction' of the electrode assembly of FIG. 4;
FIG. 6 is a schematic view illustrating a structure of a separation film of an electrode assembly constituting a battery cell according to an embodiment of the present invention after heat fusion is performed; FIG.
7 is a schematic view schematically showing a laminated structure of the electrode assembly of FIG. 6 viewed in the direction " a ";
8 is a schematic view schematically showing a laminated structure viewed from the 'd direction' of the electrode assembly of FIG. 6;
9 is a schematic view schematically showing a laminated structure viewed from the 'c direction' of the electrode assembly of FIG. 6;
10 is a partial schematic view schematically showing a lamination structure of an electrode assembly constituting a battery cell according to another embodiment of the present invention.

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

FIG. 2 is a schematic view showing a structure of unit cells constituting an electrode assembly of a battery cell according to an embodiment of the present invention.

2, the electrode assembly of the battery cell according to the present invention includes a plurality of unit cells 210, 220, 230, and 240, and each unit cell 210, 220, 230, The outermost electrodes may have a laminate structure having the same polarity, or the outermost electrodes may have a laminate structure in which the polarities of the outermost electrodes are different from each other.

That is, the unit cells may have the structure 210 in which the cathode 202 is disposed between the anode 201 and the separator 203 is interposed between the anode 201 and the cathode 202, The outermost electrodes may have a laminated structure having the same polarity as each other like the structure 220 located between the cathodes 202 and the separator 203 interposed between the cathodes 202 and the anodes, The outermost electrodes may have a laminated structure in which the polarities of the outermost electrodes are different from each other, such as the structures 230 and 240 in which a separation membrane is interposed between the cathode and the cathode.

In the unit cells, the separation membrane 203 interposed between the anode 201 and the cathode 202 protrudes longer than the anode 201 and the cathode 202 to form the extended portion 206, The extending portion 206 of the separation membrane 203 may be 1 to 20% of the length 205 of the anode 201 or the cathode 202. [

3 is a schematic view illustrating a method of constructing an electrode assembly for a battery cell according to an embodiment of the present invention.

3, the electrode assembly 300 includes a unit cell 300 having a structure in which a cathode 301 is disposed between the anode 302 and a separation membrane 309 is disposed between the anode 302 and the cathode 301, The unit cells 320 having the structure in which the separators 309 are interposed between the cathodes 301 and the anodes 302 and the anodes 302 and the anodes 302 and 330 are disposed between the cathodes 301, The positive electrode tab 304 protruded from the anode 302 and the negative electrode tab 303 protruding from the negative electrode 301 are arranged so as to face the same direction at the same position .

The electrode assembly 300 is manufactured by sequentially winding unit cells 310, 320, and 330 located on the separation film 340. The unit cells 310, 320, and 330 protrude from the unit cells 310, 308 of the extending portions 305, 306, 307, 308 of the separating film 309 adjacent to the separating film 309 are adjacent to the separating film 340 while the both extending portions 306, The extending portion 305 and the extending portion 307 opposite to the extending portion 305 are not adjacent to the separating film 340.

FIG. 4 is a schematic view schematically showing a structure of a separation film of an electrode assembly constituting a battery cell according to an embodiment of the present invention before thermal fusion bonding is performed.

Referring to FIG. 4, the electrode assembly 400 has a structure in which a plurality of unit cells 410, 420, 430, 440, and 450 are sequentially wound on a separation film 490.

Each of the unit cells 410, 420, 430, 440 and 450 has a positive electrode tab 470 and a negative electrode tab 460 protruded from one side of the outer peripheral surfaces of the positive electrode and the negative electrode, The negative electrode tab 460 protrudes from the outer surface of the unit cells 410, 420, 430, 440 and 450 on the same surface.

In this case, the outer surfaces of the unit cells 410, 420, 430, 440 and 450, on which the positive electrode tab 470 and the negative electrode tab 460 are not protruded, But the one surface on which the positive electrode tab 470 and the negative electrode tab 460 protrude and the opposite surface thereof are not adjacent to the separation film 490. [

FIG. 5 is a partial schematic view schematically showing a laminated structure viewed from the 'c' direction of the electrode assembly of FIG. 4.

5, each of the unit cells 410 and 420 of the electrode assembly 400 has a laminate structure in which the outermost electrodes have the same polarity, and one anode 412 is interposed between the two cathodes 411 and 413, And a second unit cell 420 in which one cathode 422 is interposed between the first unit cell 410 and the two anodes 421 and 423 interposed therebetween.

An electrode tab 460 protrudes from one surface of the outer surface of each of the unit cells 410 and 420. The anodes 412 and 421 and 423 of the unit cells 410 and 420 and the electrodes 411 and 413, 422, and the unit cells 410, 420 are stacked with a separation film interposed therebetween.

In this case, the separation membrane 480 and the separation film 490 are separated from each other by a separation membrane extension part L 1 protruding from the anode 412, 421, 423 and the cathode 411, 413, The separation film 490 is protruded by a length longer than the separation membrane 480 of the unit cells 410 and 420 to form the separation film extension part L2.

Specifically, the length of the separation membrane extension L1 may be 1 to 20% of the length of the anode 412, 421, 423 or the cathode 411, 413, 422, The length of the separator 480 may be 2 to 30%.

That is, the separation film 490 protrudes to a length longer than the separation membrane 480 of the unit cells 410 and 420 to form a separation film extension part.

FIG. 6 is a schematic view showing a structure of a separation film of an electrode assembly constituting a battery cell according to an embodiment of the present invention, after performing heat fusion.

Referring to FIG. 6, the electrode assembly 600 is formed with a thermal fusion region 601 in which a separation film and / or a separation film extension region are mutually coupled by thermal fusion, The positive electrode tab 670 and the negative electrode tab 660 of the cells 610, 620, 630, 640 and 650 protrude from the outer surface of the electrode assembly 600, Is formed in a part except for the part where the contact is made.

In this case, the separation membrane and / or the separation film extension portion may be formed on the outer surface of the electrode assembly 600 in which the positive electrode tab 670 and the negative electrode tab 660 of the unit cells 610, 620, 630, 640, And only the outer circumferential surfaces of the opposite surfaces of the outer surface are mutually coupled by heat fusion. The detailed structure is shown in Figs. 7 to 10.

FIG. 7 is a schematic view showing a stacked structure of the electrode assembly of FIG. 6 viewed in the "a direction" and schematically showing one surface of the positive electrode tab and the negative electrode tab protruding.

Referring to FIG. 7 together with FIG. 6, the electrode assembly 600 includes first unit cells 620 and 640 having a structure in which a cathode is disposed between the anodes and a separation membrane 680 is disposed between the anodes and the cathode, 630 and 650 having a structure in which an anode is disposed between the cathodes and a separation membrane 680 is interposed between the anode and the cathodes.

A separation film 690 interposed between the first unit cells 620 and 640 of the electrode assembly 600 and the second unit cells 610 and 630 and 650 is formed on the first and second unit cells 610 and 630 and 650, The first unit cells 620 and 640 and the second unit cells 610 and 630 are formed on the separation film 690 so as to surround the respective side surfaces of the unit cells 620 and 640 and the second unit cells 610, (610, 630, 650) are arranged and the separation film (690) is wound.

The positive electrode tab 670 and the negative electrode tab 660 of the unit cells 610, 620, 630, 640 and 650 are respectively formed on the same surface 700 of the unit cells 610, 620, 630, And a heat fusion region 601 in which the separator film and / or the separation film extension portions are mutually coupled by heat fusion is formed in a region other than the region where the positive electrode tab 670 and the negative electrode tab 660 protrude, Is formed only on the outer circumferential surface of the electrode assembly one surface (700).

FIG. 8 is a schematic view showing a layered structure of the electrode assembly of FIG. 6 viewed in the 'd' direction, and schematically showing the other surface opposite to one surface of the positive electrode tab and the negative electrode tab protruding therefrom.

Referring to FIG. 8 together with FIGS. 6 through 7, like the electrode assembly 700 in which the positive and negative tabs of the unit cells 610, 620, 630, 640 and 650 protrude, A heat-welded portion 602 is formed on the other surface 800 opposite to the heat-welded portion 800 where the extension portions of the separation film and / or the separation film are mutually coupled by heat fusion.

In this case, the heat-welded portion 602 is formed only on the outer circumferential surface of the other surface of the electrode assembly 800, like the electrode assembly 700. The outer surface 602 of the heat- And a size (S2, S3) of 10 to 50% in a minor axis direction from the outer peripheral end on the basis of the minor axis width size S1 of the other surface 800 facing the one surface 700. The electrode assembly one surface 700, (W2, W3) in the major axis direction from the outer peripheral end based on the major axis width size W1 of the other surface 800 facing the main surface 700 of the substrate.

If the size of the thermally welded outer peripheral surface 602 is less than 10% in the minor axis and the major axis direction from the outer peripheral end beyond the above range, the effect of suppressing the heat shrinkage of the desired separation film and / or separation film can not be exhibited, , The impregnating property of the electrolytic solution may be lowered.

Therefore, the battery cell according to the present invention exhibits the effect of suppressing heat shrinkage of the separator and / or the separator film in a high temperature environment, improves the insertion property of the electrode assembly in the battery case in the manufacturing process of the battery cell, It is possible to prevent degradation of the impregnation property of the catalyst.

FIG. 9 is a schematic view schematically showing a laminated structure viewed from the "c direction" of the electrode assembly of FIG. 6.

The electrode assembly 600 is extended by a length longer than the separation membrane 680 of the unit cells 610 and 620 so that the extension parts of the separation film 690 are mutually coupled 691 and 692 by heat fusion.

Therefore, the heat shrinkability of the separation film 690 is suppressed under a high temperature condition, thereby preventing internal short-circuiting of the battery cell and improving safety.

FIG. 10 is a partial schematic view schematically showing a lamination structure of an electrode assembly constituting a battery cell according to another embodiment of the present invention.

The electrode assembly 1000 is formed by protruding a length of the separation film 1090 longer than the separation membrane 1080 of the unit cells 1010 and 1020 so that the extension parts of the separation film 1090 are mutually coupled 1091 and 1092 by heat fusion.

Therefore, the heat shrinkability of the separation membrane 1080 and the separation film 1090 can be suppressed under a high-temperature condition, thereby preventing internal short-circuiting of the battery cell and improving safety.

The structure of the battery cell according to the present invention is not limited thereto and a unit cell having a laminated structure in which the polarities of the outermost electrodes are different from each other may be formed on the electrode assembly of the battery cell, .

Also, the electrode assembly of the battery cell according to the present invention may be manufactured by folding unit cells with a structure in which the separation film is wrapped in a Z-shape from the lowermost unit cell to the uppermost unit cell.

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

Claims (21)

An electrode assembly including a positive electrode, a negative electrode, a unit cell having a laminated structure composed of a separator interposed between the positive electrode and the negative electrode, and a separation film for continuously winding the unit cells are mounted on a receiving portion of the battery case;
A positive electrode tab and a negative electrode tab protruding from at least one surface of the outer surface of the positive electrode and the negative electrode of the unit cells;
The separator may protrude longer than the positive electrode and the negative electrode to form a separation membrane elongation part, wherein the separation membrane protrudes to a length longer than the separation membrane of the unit cells to form a separation membrane extension part;
Wherein the separation film extension portion is mutually coupled by thermal fusion at at least a portion of the outer surface of the electrode assembly protruding from the positive electrode tab and the negative electrode tab of the unit cells and the opposite surface of the outer surface. The battery cell according to claim 1, wherein the electrode assembly has a structure in which the unit cells are sequentially wound while being positioned on a long length of a separation film. The battery cell according to claim 2, wherein the unit cells have a laminate structure in which outermost electrodes have the same polarity. The battery cell according to claim 2, wherein the unit cells have a laminated structure in which outermost electrodes have different polarities from each other. The battery cell according to claim 1, wherein the unit cells are formed such that a positive electrode tab and a negative electrode tab protrude from the same outer surface of the unit cells. The battery cell according to claim 1, wherein the unit cells are protruded on one surface and the other surface of the unit cells facing each other on the outer surface of the unit cells. The battery cell according to claim 1, wherein the length of the separation membrane elongation part is 1 to 20% of the length of the anode or the cathode. The battery cell according to claim 1, wherein the length of the separation film extension portion is 2 to 30% of the length of the separation membrane. The battery cell according to claim 1, wherein the thermal fusion is performed for 1 to 10 seconds at a temperature in the range of 50 to 120 degrees Celsius. The battery cell according to claim 1, wherein the separation film extension portion is mutually coupled to the outer surface of the electrode assembly protruding from the positive electrode tab and the negative electrode tab of the unit cells and only the outer circumferential surface of the outer surface, . [Claim 10] The method of claim 10, wherein the thermally adhered outer circumferential surface has a 10 to 50% size portion in the minor axis direction from the outer peripheral end portion on the basis of the minor axis width size of the outer surface or the opposing surface of the electrode assembly protruding from the positive electrode tab and the negative electrode tab of the unit cells Wherein the battery cell is a battery cell. [Claim 11] The method of claim 10, wherein the thermally adhered outer circumferential surface is a 10 to 50% size portion in the major axis direction from the outer peripheral end on the outer or opposing surface of the electrode assembly protruding from the positive electrode tab and the negative electrode tab of the unit cells And the battery cell. The battery cell according to claim 1, wherein at least a part of the separation film extension part is coupled to an electrode assembly outer side where the positive and negative electrode tabs of the unit cells are protruded, . 14. The battery cell according to claim 13, wherein the separator extension part and the separator film extension part are coupled by thermal fusion. 14. The battery cell according to claim 13, wherein the separator extension part and the separator film extension part are bonded by an adhesive. The battery cell according to claim 1, wherein the separation membrane or the separation film is made of the same material. The battery cell according to claim 1, wherein the battery case comprises a laminate sheet including a resin layer and a metal layer. The battery cell according to claim 1, wherein the thermal fusion of the separation film extension is performed before inserting the electrode assembly into the battery case. The battery cell according to claim 1, wherein the battery cell is a lithium secondary battery. A device comprising at least one battery cell according to claim 1. 21. The device of claim 20, wherein the device is any one selected from the group consisting of a cell phone, a tablet computer, a notebook computer, a power tool, an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, Device.

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