KR102108113B1 - Electrode Assembly Comprising Separator Having Folded Edge - Google Patents

Abstract

The present invention is a positive electrode is coated with a positive electrode active material on the current collector; A negative electrode coated with a negative electrode active material on the current collector; And a separator interposed between the positive electrode and the negative electrode, wherein the separator has a length in which the outer peripheries extend outwardly beyond the outer peripheries of the positive and negative electrodes corresponding thereto, and the outer periphery of the separator. Among the surroundings, at least one outer periphery provides an electrode assembly characterized by being bent at least once in the inner direction.

Description

Electrode Assembly Comprising Separator Having Folded Edge

The present invention relates to an electrode assembly including a separator having an outer periphery bent.

In recent years, the increase in the price of energy sources due to the exhaustion of fossil fuels, interest in environmental pollution is amplified, and the demand for eco-friendly alternative energy sources has become an indispensable factor for future life. Accordingly, research on various power generation technologies such as nuclear power, solar power, wind power, tidal power, and the like, and power storage devices for more efficient use of the produced energy are also attracting great interest.

In particular, as technology development and demand for mobile devices increase, the demand for batteries as an energy source is rapidly increasing, and accordingly, many studies have been conducted on batteries that can meet various needs.

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

In addition, the secondary battery is classified according to the structure of the electrode assembly having a structure in which a separator interposed between the positive electrode, the negative electrode, and the positive electrode and the negative electrode is stacked. Representatively, long sheet-like positive and negative electrodes A jelly-roll type (winding type) electrode assembly with a structure wound in a state in which a separator is interposed, and a stacked (stacked) electrode assembly in which a plurality of positive and negative electrodes cut in units of a predetermined size are sequentially stacked with a separator interposed therebetween. For example, recently, in order to solve the problems of the jelly-roll type electrode assembly and the stack type electrode assembly, the electrode assembly having an advanced structure, which is a mixed form of the jelly-roll type and the stack type, has a predetermined unit. A stacked / folded electrode having a structure in which the unit cells stacked with the anode and the cathode interposed with a separator positioned on a separation film are sequentially wound. Developed body lip.

1 is a schematic diagram schematically showing an end structure of a conventional electrode assembly.

Referring to FIG. 1, the electrode assembly 100 includes an anode 110, a cathode 120, and a separator 130 interposed between the anode 110 and the cathode 120.

The separator 130 has a length in which the outer periphery 131 extends outwardly beyond the outer peripheries 111 and 121 of the positive electrode 110 and the negative electrode 120.

In general, as the separator 130 of the electrode assembly 100, an insulating thin film having high ion permeability and mechanical strength is used, for example, olefin-based polymers such as chemical resistance and hydrophobic polypropylene; Sheets or non-woven fabrics made of glass fiber or polyethylene are used.

Accordingly, when the secondary battery is operated in a high temperature condition, or when the temperature of the electrode assembly 100 itself rises abnormally due to continuous charging and discharging, shrinkage due to heat occurs. If it becomes severe, the positive electrode 110 and the negative electrode 120 come into direct contact 140, and accordingly, there is a problem of deteriorating the safety of the secondary battery because the risk of internal short-circuiting and topic generation of the secondary battery increases.

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

The present invention aims to solve the problems of the prior art as described above and the technical problems requested from the past.

The inventors of the present application after repeated in-depth studies and various experiments, as described later, at least one outer periphery among the extended outer peripheries of the separation membrane constituting the electrode assembly is configured to bend at least once in the inner direction By doing so, the outer periphery of the bent separator has a thicker thickness than other parts of the separator interposed between the positive electrode and the negative electrode, and accordingly, the outer periphery of the separator is spaced between the positive electrode and the negative electrode due to high temperature or heat. It is possible to physically prevent the shrinkage phenomenon, and accordingly, it is confirmed that it is possible to prevent the danger of internal short circuit or fire that may be caused by direct contact between the anode and the cathode, and to improve the safety of the electrode assembly. The invention has been completed.

Electrode assembly according to the present invention for achieving this object,

A positive electrode coated with a positive electrode active material on the current collector;

A negative electrode coated with a negative electrode active material on the current collector; And

A separator interposed between the anode and the cathode;

It contains,

The separator has a length in which the outer periphery extends outwardly beyond the outer periphery of the positive and negative electrodes corresponding thereto,

Among the extended outer peripheries of the separator, at least one outer periphery may be a structure that is bent at least once in the inner direction.

Therefore, the outer periphery of the bent separator has a thicker thickness than other parts of the separator interposed between the anode and the cathode, and accordingly, the outer periphery of the separator is spaced between the anode and the cathode due to high temperature or heat. It is possible to physically prevent the shrinkage phenomenon, and accordingly, it is possible to prevent an internal short circuit or a fire hazard that may be caused by direct contact between the positive electrode and the negative electrode, and improve the safety of the electrode assembly.

In one specific example, the positive electrode and the negative electrode have the same shape in a planar shape, and the negative electrode may have a structure having a relatively larger size than the positive electrode.

In general, a lithium secondary battery has a structure in which a non-aqueous electrolyte containing lithium salt is impregnated in an electrode assembly in which a porous polymer membrane is interposed between a positive electrode and a negative electrode, each of which is coated with a coating layer on a current collector. The positive electrode coating layer mainly consists of lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, and lithium composite oxide, and the negative electrode coating layer is mainly composed of carbon-based material.

However, in a lithium secondary battery using a carbon-based material as the negative electrode coating layer, irreversible capacity is generated in some lithium ions inserted into the layered structure of the carbon-based material during initial charge and discharge, resulting in a decrease in discharge capacity. In addition, since the carbon material has an oxidation / reduction potential as low as 0.1 V relative to the potential of Li / Li +, decomposition of the non-aqueous electrolyte occurs at the cathode surface, and reacts with lithium to cover the surface of the carbon material (passivating layer or solid electrolyte) interface; an SEI film) is formed. The thickness of the SEI membrane and the state of the interface vary depending on the electrolyte system used, and thus affects charge and discharge characteristics. Moreover, in a secondary battery used in a field in which high power characteristics are required, such as a power tool, even with such a thin SEI film, the resistance may be increased, resulting in a rate determining step (RDS). In addition, the lithium compound is formed on the negative electrode surface, and thus the reversible capacity of lithium gradually decreases according to repetition of charging and discharging, thereby reducing the discharge capacity and causing cycle degradation.

Therefore, in the electrode assembly according to the present invention, the positive electrode and the negative electrode have the same shape in a planar shape, thereby maximizing the area where the positive electrode and the negative electrode face each other with the separator interposed therebetween, thereby maximizing electrical performance and simultaneously dissipating the negative electrode. It is made of a relatively larger size than the anode, thereby eliminating or minimizing the problem that the discharge capacity is lowered and the SEI film is generated.

In addition, the separator may have a structure having the same shape in a plane with the anode and the cathode.

As described above, the positive electrode and the negative electrode have the same shape in a plane, and accordingly, the separator also has the same shape in a plane with the positive electrode and the negative electrode, thereby completely separating the positive electrode and the negative electrode. Direct contact can be prevented.

However, the shape of the separator is not limited thereto, and the outer periphery extends outwardly compared to the outer periphery of the positive electrode and the negative electrode corresponding thereto, so as to completely separate the positive electrode and the negative electrode between the positive electrode and the negative electrode, Of course, if at least one outer periphery is a structure that can be bent one or more times in the inner direction, it may be of course made of a different shape in a plane with the anode and the cathode.

However, the separator is made of the same shape in a plane with the positive electrode and the negative electrode, thereby minimizing the use of unnecessary separators, thereby minimizing the cost required for manufacturing the electrode assembly.

On the other hand, among the extended outer periphery of the separator, the length of the remaining outer periphery except for the outer periphery bent in the inner direction is 1% to 30% of the width or length of the positive and negative electrodes corresponding to the extended direction. It may be a structure consisting of.

If, among the extended outer peripheries of the separator, the length of the outer periphery except for the outer periphery bent in the inner direction is too small outside the above range, even if the remaining outer peripheries of the separator are finely shrunk, it is desired. On the contrary, if it is too large outside the above range, the overall size of the electrode assembly including the separation membrane becomes too large, or an unnecessary portion of the separation membrane occurs, resulting in the manufacturing cost of the electrode assembly. There is a problem that this increases.

In one specific example, among the extended outer peripheries of the separation membrane, an extended length of the outer periphery bent in the inner direction may be a structure having a size of 200% to 800% with respect to the extended length of the remaining outer periphery.

In this case, among the extended outer peripheries of the separator, an extended length after the outer periphery bent in the inner direction is bent may have the same structure as the remaining outer peripheries.

As described above, the outer periphery of the separator that is bent in the inner direction may have a structure that is bent at least once.

Accordingly, the outer periphery of the separator bent in the inner direction extends beyond the outer peripheries of the positive and negative electrodes corresponding to the final direction and extends in the outer direction, and the length of the outer periphery after being bent in the inner direction is the rest. By achieving the same structure as the surrounding extension length, it is possible to more easily prevent shrinkage of the separator due to heat while maintaining the same size as the conventional electrode assembly.

If, among the extended outer peripheries of the separation membrane, the length of the outer periphery bent in the inner direction is less than 200% of the length of the outer periphery, the length of the outer periphery bent in the inner direction May be too short, and may not exert the desired effect. Conversely, when the extension length of the outer periphery bent in the inner direction exceeds 800% of the remaining lengths of the outer periphery, in the inner direction The problem is that the thickness of the outer periphery of the bent separator becomes excessively thick, and interference with the separator located at different sites occurs, or accordingly, the structural stability of the electrode assembly may be reduced, such as a decrease in the adhesion between the anode and the cathode to the separator. There is this.

In addition, among the extended outer peripheries of the separator, the thickness after the outer periphery bent in the inner direction is bent may have a structure having a size of 20% to 100% with respect to the thickness of an adjacent anode or cathode.

If the thickness after the outer periphery bent in the inner direction is less than 20% of the thickness of the adjacent positive electrode or negative electrode, the thickness after the bent is too thin, and may not exert the desired effect. When the thickness of the adjacent anode or cathode exceeds 100%, as described above, structural stability of the electrode assembly may be deteriorated, such as a decrease in adhesion between the anode and the cathode to the separator.

Meanwhile, among the extended outer peripheries of the separator, the outer periphery bent in the inner direction may be a structure that is thermally fused after being bent.

More specifically, when the extended outer peripheries of the separator are bent in the inner direction, due to the physical properties of the separator, when the film is returned to its original state or contracted by heat of the separator, it is stably bent into the inside of the separator. The contraction of the outer periphery cannot be prevented. Accordingly, among the extended outer peripheries of the separator, the outer periphery bent in the inner direction is thermally fused after being bent, thereby stably maintaining the bent state, and the separator It is possible to prevent direct contact between the anode and the cathode due to thermal contraction.

At this time, the heat fusion may be performed in a temperature range of 40 to 150 degrees Celsius.

If the heat fusion is performed in a temperature range of less than 40 degrees Celsius, the heat fusion temperature may be too low to exert the desired heat fusion effect, and the heat fusion temperature exceeds 150 degrees. When performed in the range, the extended outer periphery of the separator may be contracted, damaged or deformed by the heat fusion.

In one specific example, among the extended outer peripheries of the separator, at least two or more outer peripheries bent in the inner direction, and the lengths of the outer peripheries bent in the inner direction may have the same or different structures.

More specifically, the general electrode assembly includes at least two or more outer peripheries, and accordingly, the electrode assembly according to the present invention also includes at least an outer periphery bent in an inner direction among the extended outer peripheries of the separator. By including two or more places, it is possible to effectively prevent shrinkage of the separator due to heat.

In this case, the lengths of the outer peripheries bent in the inner direction may be the same or different from each other, and more specifically, the electrode assembly may have various shapes such as circular, triangular, square, or polygonal shapes in a plane. Since the length of each outer periphery may also vary, the outer periphery having a relatively high probability of contraction due to heat may have a longer extension length.

In addition, the positive electrode, the negative electrode, and the separator may be formed in a rectangular shape on a plane, and among the extended outer peripheries of the separator, only the outer peripheries of both sides having a relatively short length may be bent inward.

In general, when the positive electrode, the negative electrode, and the separator are formed in a rectangular shape on a plane, the extended outer peripheries of the separator have a first outer periphery and a third outer periphery having a relatively short length, and a relatively long length. It may have a second outer periphery and a fourth outer periphery.

In this case, the distance between the first outer periphery and the third outer periphery has a longer length than the lengths of the second outer periphery and the fourth outer periphery, and accordingly, shrinkage may occur at the same rate between each outer periphery. In this case, the contraction length due to heat generated between the first outer periphery and the third outer periphery may be relatively greater between the second outer periphery and the fourth outer periphery.

Therefore, in the electrode assembly according to the present invention, when the positive electrode, the negative electrode, and the separator are formed in a rectangular shape in a plane, only the outer peripheral sides of both sides having at least a relatively short length among the extended outer peripheries of the separator are inward. By bending, it is possible to minimize the shrinkage of the membrane.

Here, in order to maximize the effect of the present invention, regardless of the length of the extended outer periphery of the separation membrane, all of course may be bent in the inner direction.

On the other hand, the present invention provides a battery cell including the electrode assembly, wherein the electrode assembly includes electrode terminals extending in one direction or opposite directions to each other, and at least two or more electrodes so that the electrode terminals are exposed It may be a structure in which the assemblies are wound up by a long sheet-shaped separation film and embedded in a battery case together with an electrolyte.

In this case, the separation film may have a structure in which the outer periphery of the separation film of the area where the electrode terminals are exposed and / or the area opposite to it is relatively extended compared to the outer periphery of the positive electrode and the negative electrode.

More specifically, the separation film may be a structure in which the electrode terminals of the electrode assembly are exposed to the outside and are wound in a form surrounding a side portion of the electrode assembly so as to be interposed between each electrode assembly.

Therefore, when the separation film is contracted by heat, contraction may occur at an area where the electrode terminals of the electrode assembly are exposed and / or an area opposite thereto, and to prevent a problem, the separation film is exposed by the electrode terminals The outer periphery of the separation film of the separated region and / or the opposing portion may have a structure that is relatively extended compared to the outer periphery of the positive electrode and the negative electrode.

At this time, the separation film may have a structure in which the extended outer periphery of the exposed portion of the electrode terminals and / or the portion facing the electrode is bent one or more times in the inner direction.

In other words, since the separation film is interposed between the outermost anode and the cathode of the electrode assemblies adjacent to each other, like the separation film interposed between the anode and the cathode of the electrode assembly, the separation film may also cause problems due to heat shrinkage. As an area, the extended outer periphery of the area where the electrode terminals are exposed and / or the area opposite thereto is bent one or more times in the inner direction, and by thermal contraction of the separation film, the outermost anode of the electrode assemblies adjacent to each other It is possible to prevent the phenomenon that the cathode directly contacts.

In addition, like the separator interposed between the positive electrode and the negative electrode of the electrode assembly, the thickness of the bent extended outer periphery of the separation film is 20% to 100% of the thickness of the positive electrode or the negative electrode of the adjacent electrode assembly. It can be size.

If the thickness of the bent outer periphery is less than 20% of the thickness of the positive electrode or the negative electrode of an adjacent electrode assembly, the bent outer periphery is too thin, and may not exhibit the desired effect. When the thickness of the positive electrode or the negative electrode of the adjacent electrode assembly exceeds 100%, there is a problem that structural stability may be deteriorated, such as a decrease in adhesion between the positive electrode and the negative electrode of the electrode assemblies facing the separation film.

In addition, the bent extended outer periphery of the separation film may be a heat-sealed structure, and accordingly, due to the physical properties of the separated film, the bent extended outer periphery returns to its original state And by stably maintaining the bent state of the outer periphery, it is possible to effectively prevent the phenomenon of direct contact between the anode and the cathode of the electrode assemblies adjacent to each other by thermal contraction of the separation film.

On the other hand, the present invention provides a method for manufacturing the battery cell, the method for manufacturing the battery cell,

a) preparing two or more electrode assemblies in which the outer periphery of the separator is relatively longer than the outer periphery of the positive electrode and the negative electrode;

b) thermally welding the outer periphery of the region where the electrode terminals are extended and / or the region opposite to the outer periphery of the separation membrane of the electrode assemblies in an inner direction;

c) the electrode terminals of the electrode assemblies are arranged on a long sheet-shaped separation film so that they are aligned in the same direction or in directions opposite to each other;

d) bending the outer periphery of a portion corresponding to the electrode terminals of the electrode assemblies and / or a portion facing the electrode among the outer peripheries of the separation film;

e) winding the electrode assemblies with a separation film;

f) sealing the electrode assemblies wound up by the separation film together with an electrolyte in a battery case;

It may include.

That is, among the outer circumferences of the separation film constituting the battery cell, the outer circumference of the portion corresponding to the electrode terminals of the electrode assemblies and / or the portion opposite to the electrode terminals is wound around the electrode assemblies for easier manufacturing. Prior to this, it is bent and heat-sealed.

The present invention also provides a device including a battery pack including a battery cell and a private battery pack as a power source, wherein the device is a mobile phone, a tablet computer, a notebook computer, a power tool, a wearable electronic device, an electric vehicle, a hybrid It may be any one selected from the group consisting of electric vehicles, plug-in hybrid electric vehicles, and power storage devices.

Since the battery pack and the device are known in the art, detailed descriptions thereof will be omitted herein.

As described above, the electrode assembly according to the present invention is configured such that at least one outer periphery is bent at least one time in the inner direction among the extended outer peripheries of the separator constituting the electrode assembly, and thus the outer side of the bent separator. The periphery has a thicker thickness than other parts of the separator interposed between the positive electrode and the negative electrode, thereby physically preventing the phenomenon that the outer periphery of the separator is contracted into the space between the positive electrode and the negative electrode by high temperature or heat. Accordingly, it is possible to prevent an internal short circuit or a fire hazard that may be caused by direct contact between the anode and the cathode, and improve the safety of the electrode assembly.

1 is a schematic view schematically showing an end structure of a conventional electrode assembly;
2 is a schematic diagram schematically showing the structure of an electrode assembly according to an embodiment of the present invention;
3 is a schematic view schematically showing a pre-winding structure of an electrode assembly assembly constituting a battery cell according to another embodiment of the present invention;
4 is a vertical cross-sectional view schematically showing an outer peripheral structure of the electrode assembly assembly of FIG. 3.

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

2 is a schematic diagram schematically showing the structure of an electrode assembly according to an embodiment of the present invention.

Referring to FIG. 2, the electrode assembly 200 includes an anode 210, a cathode 220, and a separator 230 interposed between the anode 210 and the cathode 220.

The positive electrode 210, the negative electrode 220, and the separator 230 are formed in a rectangular shape in a planar shape, and the negative electrode 220 has a relatively large size compared to the positive electrode 210.

The positive electrode 210 and the negative electrode 220 respectively include a positive electrode terminal 215 and a negative electrode terminal 225 formed in the same outer peripheral direction.

The separator 230 has a larger size than the positive electrode 210 and the negative electrode 220, and accordingly, the outer peripheries 231, 232, 233, and 234 of the separator 230 have a positive electrode 210 corresponding thereto. It extends beyond the outer periphery of the negative electrode 220 and outward.

Among the outer peripheries 231, 232, 233, and 234 of the separator 230, the second outer periphery 232 adjacent to the first outer periphery 231 in the direction in which the positive terminal 215 and the negative terminal 225 protrude. ) And the extension lengths 232a and 234a of the fourth outer periphery 234 are the same as each other, and the extension length 231a of the first outer periphery 231 is based on the outer periphery of the anode 210. The outer periphery 232 and the fourth outer periphery 234 have a size of 200% with respect to the extended lengths 232a and 234a.

The extended length 233a of the third outer periphery 233 facing the first outer periphery 231 is based on the outer periphery of the anode 210, and the second outer periphery 232 and the fourth outer periphery 234 ) Of 300% of the extended lengths 232a and 234a.

According to the above structure, the first outer periphery 231 and the third outer periphery 233 of the separator 230 are bent once and twice in the inner direction, respectively, and after the first outer periphery 231 and 3 The extended lengths 231b and 233b of the outer periphery 233 are the same as the extended lengths 232a and 234a of the second outer periphery 232 and the fourth outer periphery 234, respectively.

Here, the first outer periphery 231 is bent at a smaller number of times than the third outer periphery 233 facing it, so as to avoid interference with the positive terminal 215 when bending.

The first outer periphery 231 and the third outer periphery 233 are heat-sealed in an inwardly bent state, and accordingly, the separation membrane 230 except for the first outer periphery 231 and the third outer periphery 233 It has a thicker thickness (231c, 233c) than the rest of the.

Here, both of the first outer periphery 231 and the third outer periphery 233 have a thickness 231c, 233c that is thinner than that of the anode 210 in a state in which they are bent inwardly, and are separated from the separators of adjacent electrode assemblies. Interference can be avoided.

Therefore, when the separator 230 contracts due to high temperature or heat, the first outer periphery 231 and the third outer periphery 233 may be physically prevented from contracting due to their relatively thick thickness.

3 is a schematic diagram schematically showing a pre-winding structure of an electrode assembly assembly constituting a battery cell according to another embodiment of the present invention.

Referring to FIG. 3, electrode assemblies 301, 302, and 303 having the same structure as the electrode assembly 200 of FIG. 2 are arranged alternately on the long sheet-shaped separation film 340.

The electrode assemblies 301, 302, and 303 each include a positive terminal 315 and a negative terminal 325 formed in the same direction, and on a separation film 340, the positive terminal 315 and the negative terminal 325 ) Are all aligned in the same direction.

In the separation film 340, the extended outer periphery 341 of the portion where the positive electrode terminal 315 and the negative electrode terminal 325 are exposed and the extended outer periphery 342 of the opposite portion thereof are inward once and twice, respectively. It has been folded (351, 352).

The separation film 340 has an extended outer periphery 341 of an area where the positive electrode terminal 315 and the negative electrode terminal 325 of the electrode assemblies 301, 302, and 303 are exposed, and an extended outer periphery of the opposite portion thereof. After the 342 is bent 351, 352, the electrode assemblies 301, 302, 303 are sequentially wound 353 from the first electrode assembly 301 to the second electrode assembly 302.

According to the above structure, the separation film 340 is interposed between each adjacent electrode assembly 301, 302, 303.

4 is a vertical cross-sectional view partially showing the structure of the electrode assembly assembly of FIG. 3.

4, the separation film 340 is interposed between the electrode assemblies (303, 305, 307, 309).

Each electrode assembly (303, 305, 307, 309) of the outer periphery of the separation membrane 330, the positive electrode terminal 315 and the negative electrode terminal 325 is formed in the extended outer periphery 331 and opposite thereto The outer periphery 332 is bent inward.

The separation film 340 located between each electrode assembly 303, 305, 307, 309 also exposes the positive electrode terminal 315 and the negative electrode terminal 325 of the electrode assemblies 303, 305, 307, and 309. The extended outer periphery 341 of the portion and the outer periphery 342 opposite thereto are bent in the inner direction, and thus have relatively thick thicknesses 341c and 342c compared to other portions of the separation film 340.

Therefore, when the separation film 340 interposed between the separation membrane 330 of the electrode assemblies 303, 305, 307, and 309 and the electrode assemblies 303, 305, 307, and 309 is shrunk by high temperature or heat, Since the physical shrinkage is prevented, it is possible to prevent the occurrence of an internal short circuit or fire due to direct contact between the anode 310 and the cathode 320.

Those skilled in the art to which the present invention pertains will be able to make various applications and modifications within the scope of the present invention based on the above.

Claims (20)

A positive electrode coated with a positive electrode active material on the current collector;
A negative electrode coated with a negative electrode active material on the current collector; And
A separator interposed between the anode and the cathode;
It contains,
The separator has a length in which the outer periphery extends outwardly beyond the outer periphery of the positive and negative electrodes corresponding thereto,
Among the extended outer peripheries of the separator, at least one outer periphery is bent at least once so that it is bent in the inner direction, which is the central direction of the separator, and completely overlapped,
The thickness of the bent outer periphery among the extended outer peripheries of the separator becomes thicker than the thickness of the outer periphery that is not bent,
Among the extended outer peripheries of the separator, the outer periphery bent in the inner direction is thermally fused after being bent, so that an electrode assembly is formed. The electrode assembly of claim 1, wherein the positive electrode and the negative electrode have the same shape in a planar shape, and the negative electrode has a relatively larger size than the positive electrode. The electrode assembly according to claim 1, wherein the separation membrane is formed in the same shape as the anode and the cathode in a planar shape. According to claim 1, Among the extended outer periphery of the separation membrane, the length of the remaining outer periphery except for the outer periphery bent in the inner direction is 1% to about the width or length of the positive and negative electrodes corresponding to the extended direction. Electrode assembly characterized in that it is made of a size of 30%. The electrode assembly of claim 1, wherein an extended length of the outer periphery bent in an inner direction among the extended outer peripheries of the separation membrane is 200 to 800% of the length of the remaining outer periphery. . The electrode assembly according to claim 5, wherein an extended length after the outer periphery bent in the inner direction among the extended outer peripheries of the separator is the same as the rest of the outer periphery. According to claim 1, Among the extended outer periphery of the separator, the thickness after the outer periphery bent in the inner direction is bent, characterized in that made of a size of 20% to 100% with respect to the thickness of the adjacent anode or cathode Electrode assembly. delete The electrode assembly of claim 1, wherein the heat fusion is performed in a temperature range of 40 degrees to 150 degrees Celsius. The electrode of claim 1, wherein, among the extended outer peripheries of the separation membrane, at least two or more outer peripheries bent in the inner direction, and the lengths of the outer peripheries bent in the inner direction are the same or different from each other. Assembly. The method of claim 1, wherein the positive electrode, the negative electrode and the separator are formed in a rectangular shape in a plane, and among the extended outer peripheries of the separator, only the outer peripheries on both sides having a relatively short length are bent inward. Electrode assembly to be made. A battery cell comprising the electrode assembly according to claim 1,
The electrode assembly includes electrode terminals extending in one direction or in opposite directions opposite to each other, and at least two or more electrode assemblies are wound by a long sheet-shaped separation film so that the electrode terminals are exposed, together with an electrolyte. Built in the battery case,
In the separation film, the outer periphery of the separation film of the area where the electrode terminals are exposed and / or the area opposite to the separation film extends relative to that of the positive and negative electrodes.
The separation film is bent one or more times so that the extended outer periphery of the exposed portion of the electrode terminals and / or the opposite portion thereof is bent in the inner direction, which is the central direction of the positive electrode and the negative electrode, and completely overlapped,
The thickness of the bent outer periphery among the extended outer peripheries of the separator becomes thicker than the thickness of the outer periphery that is not bent,
A battery cell, characterized in that among the extended outer peripheries of the separator, the outer periphery bent in the inner direction is thermally fused after being bent. delete delete The battery cell according to claim 12, wherein the thickness of the extended outer periphery of the separation film is 20% to 100% of the thickness of the positive electrode or the negative electrode of the adjacent electrode assembly. delete A method for manufacturing a battery cell according to claim 12,
a) preparing two or more electrode assemblies in which the outer periphery of the separator is relatively longer than the outer periphery of the positive electrode and the negative electrode;
b) bending the outer periphery of an extended portion of the electrode terminals and / or an opposite portion of the outer periphery of the separation membrane of the electrode assemblies in an inner direction to heat-seal them;
c) the electrode terminals of the electrode assemblies are arranged on a long sheet-shaped separation film so that they are aligned in the same direction or in directions opposite to each other;
d) bending the outer periphery of a portion corresponding to the electrode terminals of the electrode assemblies and / or a portion facing the electrode among the outer peripheries of the separation film;
e) winding the electrode assemblies with a separation film;
f) sealing the electrode assemblies wound up by the separation film together with an electrolyte in a battery case;
Battery cell manufacturing method comprising a. A battery pack comprising the battery cell according to claim 12. A device comprising the battery pack according to claim 18 as a power source. The device of claim 19, wherein the device is any one selected from the group consisting of a mobile phone, a tablet computer, a laptop computer, a power tool, a wearable electronic device, an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, and a power storage device. Device characterized in that.

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