KR101728006B1 - Battery Case Comprising Variable Elongation Part - Google Patents

Abstract

The present invention relates to an electrode assembly that incorporates an electrode assembly capable of bending or bending in accordance with the shape of a device to which a battery cell is to be mounted and at least one of the surfaces facing the outer surface of the electrode assembly has one or more variable The battery case includes a variable elongation part.

Description

[0001] The present invention relates to a battery case including a variable elongating part,

The present invention relates to a battery case including a variable extending portion.

As information technology (IT) technology has developed remarkably, various portable information and communication devices have been spreading, so that the 21st century is being developed into a "ubiquitous society" capable of providing high quality information services regardless of time and place.

As a development base for such a ubiquitous society, a lithium secondary battery occupies an important position. Specifically, the rechargeable lithium secondary battery is widely used as an energy source for wireless mobile devices, and is proposed as a solution for air pollution of existing gasoline vehicles and diesel vehicles using fossil fuels And also as an energy source for electric vehicles, hybrid electric vehicles, and the like.

As described above, as the devices to which the lithium secondary battery is applied are diversified, the lithium secondary battery has been diversified so as to provide a suitable output and capacity for the applied device. In addition, compactness and lightness are strongly demanded.

The lithium secondary battery may be classified into a cylindrical battery cell, a prismatic battery cell, and a pouch-shaped battery cell depending on its shape. Among them, a pouch-type battery cell which can be stacked with a high degree of integration, has a high energy density per unit weight, and is inexpensive and easy to deform is attracting much attention.

FIGS. 1 and 2 schematically show a general structure of a typical pouch-type secondary battery of the related art as an exploded perspective view.

1, a pouch type secondary battery 10 includes a stacked electrode assembly 20 having a plurality of electrode tabs 21 and 22 protruding therefrom, two stacked electrode assemblies 20 and 22 connected to the electrode tabs 21 and 22, And a battery case 40 having a structure in which the stacked electrode assembly 20 is received and sealed such that a part of the electrode leads 30 and 31 and a part of the electrode leads 30 and 31 are exposed to the outside.

The battery case 40 includes a lower case 42 including a concave shaped storage portion 41 on which the stacked electrode assembly 20 can be placed and a stacked electrode assembly 20 And an upper case 43 for sealing the upper case 43. The upper case 43 and the lower case 42 are thermally fused together with the stacked electrode assembly 20 so that the upper end sealing portion 44 and the side sealing portions 45 and 46 and the lower end sealing portion 47 ).

Although the upper case 43 and the lower case 42 are shown as separate members in Fig. 1, a hinged structure in which one end portion is continuous and continuous as in Fig. 2 is also possible.

1 and 2 show a pouch-shaped battery cell having a structure in which electrode terminals having a structure in which an electrode tab and an electrode lead are connected together at one end, a structure in which electrode terminals are formed at one end and at the other end, respectively The pouch-shaped battery cell of the present invention can also be manufactured in the same manner as described above.

1 and 2 illustrate a pouch-type battery cell using a stacked electrode assembly. However, it is needless to say that the present invention can also be applied to the case where a wound-up type or jelly-roll type electrode assembly is used.

As shown in Figs. 1 and 2, the pouch-shaped battery cell is generally manufactured in a substantially rectangular parallelepiped shape.

However, the design of the device may not only be formed in a rectangular parallelepiped shape, but may also be a shape that can be bent. For example, in the case of a smart phone, curved side processing can be performed to improve gripping feeling. In the case of a flexible display, it can be bent or bent, and can be manufactured in various forms.

In the case of a device designed to have such a curved portion or a device capable of being bent, there is a problem in that it is difficult to embed a rectangular parallelepiped-shaped battery cell or a battery pack in a space inside the device. Recently, Flexible characteristics of a battery that can be easily mounted in a device are required.

Therefore, there is a high need for a technique capable of preventing the occurrence of unintended wrinkles of the outer casing and ensuring safety even when the shape of the battery is deformed.

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.

The inventors of the present application have conducted intensive research and various experiments and have found that when a battery case including a variable elongating portion that is elongated when the electrode assembly is bent or bent is used to manufacture a battery cell, It is possible to prevent unintentional occurrence of wrinkles in the battery case and to secure safety, thereby completing the present invention.

According to an aspect of the present invention, there is provided a battery case,

Wherein at least one of the surfaces facing the outer surface of the electrode assembly has at least one variable elongating portion extending when the electrode assembly is bent or bent, variable elongation part.

Generally, when a battery cell is subjected to deformation such as bending or bending, unexpected wrinkles or folds may occur on a part of the surface of the battery case which contacts the electrode assembly, As the battery is repeatedly worn, the battery case may be damaged, resulting in leakage of the electrolyte, and loss of the insulation function of the battery case.

However, in the battery cell according to the present invention, the battery case includes a variable extension portion that can be stretched corresponding to the outer surface length of the electrode assembly. When the battery cell is deformed, unintended wrinkles or folds It is possible to secure safety.

The battery case may include an upper case facing the upper surface of the electrode assembly and a lower case facing the lower surface of the electrode assembly. The variable extending portion includes upper and lower cases facing the outer surface of the electrode assembly, It is preferable that the electrode assembly is formed at a position close to the bent or bent surface so as to facilitate stretching or non-stretching in correspondence with the bending or bending of the battery cell. Further, in order to allow bending or bending in both directions, the variable extension portion may be formed on each of a case surface corresponding to the upper surface of the electrode assembly in the upper case and a case surface corresponding to a lower surface of the lower case middle electrode assembly, respectively .

The length of the case surface facing the outer surface of the electrode assembly corresponds to the outer surface length of the electrode assembly in the unstretched state and the length of the surface of the case facing the outer surface of the electrode assembly in the extended state corresponds to the outer surface of the electrode assembly It may be a structure longer than the length

At this time, the length of the case surface facing the outer surface of the electrode assembly in the stretched state may be 102% to 140% of the outer surface length of the electrode assembly.

If the length of the case surface due to stretching is smaller than the above range, the intended effect of the present invention can not be achieved. If the length is larger than the above range, undesirable wrinkles or folding may occur due to excessive stretching of the battery case Therefore, it is not preferable.

More specifically, the variable extension portion is not limited as long as it has a structure capable of being stretched in accordance with bending or bending of the battery cell as described above, but may be a foldable structure in which the battery case is bent.

The folding type structure is a structure in which the battery case is bent at least once so that the valleys and the floor are formed in a direction perpendicular to the electrode assembly. In the folding direction, more specifically, a virtual plane The electrode assembly may be formed so as to protrude in a direction opposite to the direction in which the electrode assembly is built, or may protrude in a direction in which the electrode assembly is embedded with reference to a virtual plane of the case surface on which the variable extension portion is not formed, And may be formed so as to protrude in the direction opposite to the direction in which it is formed.

The bending direction of the folding type structure may be appropriately selected in accordance with the purpose of use of the battery cell. Specifically, the bending direction of the folding type structure may be selected such that the electrode assembly is protruded in the direction opposite to the direction in which the electrode assembly is housed The formed structure is difficult in the labeling process of the battery cell, but it does not affect the size of the accommodating space in which the electrode assembly is housed, minimizing the dead space, and thus the movement of the electrode assembly is small, desirable. On the other hand, in the configuration in which the electrode assembly is protruded in the direction in which the electrode assembly is embedded with respect to the virtual plane of the case surface on which the variable extension portion is not formed, the size of the accommodation space in which the electrode assembly is built- But it is preferable in the case where there is no difficulty in the labeling process and the external shape is substantially different from the conventional battery cell in appearance and the external shape is important. On the other hand, in the configuration in which the variable extension portion protrudes in the opposite direction to the direction in which the electrode assembly is built, the protrusion height in both directions is smaller than the protrusion height in the protrusion in the one direction, . Here, the protruding height of the variable elongating portion refers to the shortest distance in the direction perpendicular to the electrode assembly with respect to the virtual plane of the case surface on which the variable elongating portion is not formed, And can be appropriately selected depending on the degree of bending.

The variable stretching portion of such a folding type structure can be separately formed at the time of forming the cell case or after the forming process. Here, the forming step includes a deep drawing step of forming a space for accommodating the electrode assembly in the upper case and the lower case, and a step of forming the upper case corresponding to the size of the lower case in the case of forming the accommodation space only in the lower case .

Specifically, in order to form the variable extension portion in the forming process, the upper jig or the lower jig for case forming may be configured to include a desired folding-type structure. In order to form the variable extension portion after the deep drawing process, Or by separately taking a picture in a battery case where the foaming process is completed using a brass forming jig. At this time, a jig including a shape of a folding-type structure may be selected according to the bending direction of the folding type structure. For example, a jig having a variable extension portion is formed on a lower case including a receiving space of the electrode assembly In order to form the variable extension portion so as to protrude in the direction opposite to the direction in which the electrode assembly is housed with respect to the virtual plane, the upper drawing jig may be configured to include the shape of the folding-type structure and a variable extension portion is formed In order to form the electrode assembly in such a manner that the electrode assembly protrudes in the direction in which the electrode assembly is embedded with respect to the virtual plane of the case surface where the electrode assembly is not present, it is preferable that the variable jig includes the shape of the folding- In order to form each protruding in the opposite direction In a direction against the upper jig and the lower jig it can be made by configured to include the shape of the foldable structure.

When the battery cell is bent or bent, the deformed portion of the electrode assembly causes the elongated portion of the battery case to partially loosen the valleys and the floor of the variable elongating portion and to face the outer surface of the electrode assembly The length of the battery case is longer than the length of the outer surface of the electrode assembly, and the compressed portion deepens the valleys and floor of the variable elongating portion, thereby minimizing the occurrence of unintentional wrinkles other than the variable elongating portion on the battery case.

In addition, since the variable extending portion of the battery case can be extended in accordance with the volume change of the electrode assembly, it is possible to secure a space of the cell case due to contraction and expansion of the electrode assembly, It is possible to remarkably reduce the stress.

The formation direction of the folding type structure is determined depending on the bending or bending direction of the battery cell and is not limited. For example, the direction in which the electrode terminal is to be formed may be a lengthwise or widthwise direction of the battery case .

The number of variable extending portions formed in the battery case may be variously applied according to the type of the device to which the battery cell is mounted, that is, the degree of bending or flexing, and more particularly, The variable extension portions may be spaced apart from one another, and the spaced apart intervals of the variable extension portions may vary from 1 to 5 times the width of the variable extension portion depending on the degree of bending or bending of the battery cells. Can be selected. Here, the gap means a distance at which the variable extension portions do not overlap with each other in a state where the electrode assembly is not bent or bent.

In the case where the variable extension portions are formed so as to be spaced apart from each other as described above, since the variable extension portions can be formed concentrically only on the portion where bending or bending frequently occurs, the occurrence of wrinkles can be effectively prevented, As the use is reduced, the manufacturing cost can be reduced.

The interval may be constant or irregular. Considering that bending or bending of the battery cell is mainly performed at the center portion, the gap is narrow at the center portion so that a large number of variable stretching portions exist at the center portion of the battery case, It may be a losing structure.

Also, the position of the variable extension portion is not limited, but may be formed to include the center portion of the battery case in consideration of bending or bending of the battery cell mainly in the center portion.

Meanwhile, the battery case for exhibiting the above-mentioned effects including such a variable stretching portion is preferably a case having high flexibility and high elongation, and more specifically, it may be a pouch type case made of a laminate sheet including a metal layer and a resin layer .

At this time, the laminate sheet may be an aluminum laminate sheet, more specifically, a resin outer layer having excellent durability is added to one surface (outer surface) of the metal layer, and a thermally fusible resin sealant layer is added to the other surface Structure.

Since the resin outer layer has excellent resistance from the external environment, it is necessary to have a tensile strength and weather resistance of a predetermined level or higher. In this respect, polyethylene terephthalate (PET) and stretched nylon film can be preferably used as the polymer resin of the resin outer layer.

The metal layer may be made of aluminum so as to exhibit a function of improving the strength of the battery case, in addition to a function of preventing foreign matter such as gas and moisture from leaking or leaking.

As the polymer resin of the resin sealant layer, a polyolefin resin having a low heat absorbing property (heat adhesion property) and low hygroscopicity in order to suppress penetration of an electrolyte solution and not being swollen or eroded by an electrolytic solution is preferably used And more particularly, lead-free polypropylene (CPP) may be used.

In general, a polyolefin resin such as polypropylene has a low adhesive force with a metal, and therefore, as a method for improving the adhesion to the metal layer, more specifically, it includes an adhesive layer between the metal layer and the resin sealant layer, The characteristics can be improved. Examples of the material of the adhesive layer include a urethane-based material, an acryl-based material, a composition containing a thermoplastic elastomer, and the like, but are not limited thereto.

The present invention also relates to the battery case, And an electrode assembly capable of bending or flexing according to a shape of a device on which the battery cell is mounted.

The electrode assembly is embedded in a battery case in a state of being impregnated with an electrolytic solution and is not particularly limited. The electrode assembly may be a jelly-roll type electrode assembly having a structure in which long sheets of positive and negative electrodes are wound with a separator interposed therebetween, A stacked electrode assembly in which a plurality of positive electrodes and negative electrodes cut in units of a predetermined size are sequentially stacked with a separator interposed therebetween or a stacked electrode assembly in which a predetermined number of positive electrodes and negative electrodes are stacked with a separator interposed therebetween, ) Stacked or folded type electrode assembly in which full cells are wound in a separating film, or a laminate / stacked electrode assembly in which a bi-cell or pull-cell is stacked with a separator interposed therebetween.

In this case, the bi-cell may have a structure in which a first electrode, a separation membrane, a second electrode, a separation membrane, and a first electrode are sequentially stacked, and the pull cell may have a structure in which a first electrode, a separation membrane, and a second electrode are sequentially stacked.

Here, the first electrode and the second electrode are electrodes having opposite polarities. For example, the first electrode may be an anode or a cathode. In this case, the second electrode may be a cathode or an anode.

The present invention also provides a battery pack including the battery cell as a unit cell and the battery pack as a power source.

The device may be, for example, a cellular 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, a plug- And the like.

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 case according to the present invention includes a variable stretching portion that can be stretched corresponding to the outer surface length of the electrode assembly that is bent or bent. When the battery cell is manufactured by applying the same, Unexpected wrinkles or folds can be prevented from being generated on the battery case even when the battery case is deformed. Therefore, safety of the battery can be secured by effectively preventing the dielectric breakdown or electrolyte leakage due to the exposure of the metal layer There is an effect that can be done.

Further, even when the electrode assembly is deformed due to shrinkage and expansion, the variable stretching portion of the battery case can be stretched corresponding to the volume of the electrode assembly, so that it is possible to secure a space of the battery case due to contraction and expansion of the electrode assembly, The stress generated between the electrode assembly and the battery case can be remarkably reduced.

1 and 2 are exploded perspective views of a conventional pouch type secondary battery of the related art;
3 is a top view and a vertical cross-sectional view of a battery cell according to one embodiment of the present invention;
4 is an enlarged schematic view of part A of Fig. 3;
5 is a schematic view showing a form in which the variable stretching portion of FIG. 4 is stretched;
FIG. 6 is a schematic view showing a bent form of a battery cell according to an embodiment of the present invention; FIG.
7 is a vertical cross-sectional view of a battery cell for illustrating another structure of the variable extension portion according to the present invention;
8 is a vertical sectional view of a battery cell for illustrating another structure of the variable extension portion according to the present invention;
9 is a plan view of a battery cell for illustrating another positional structure of the variable elongation unit according to the present invention;
10 is a plan view of a battery cell according to another embodiment of the present invention.

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

3 is a plan view of a battery cell 100 according to an embodiment of the present invention and a vertical cross-sectional view cut along a plane P, and FIG. 4 is a cross-sectional view of the battery cell 100 in which the variable extending portion 150 is enlarged A schematic diagram is shown.

Referring to these drawings, a battery cell 100 is a battery cell in which an electrode assembly 110 having a structure in which an anode 112 and a cathode 114 are laminated with a separator 113 interposed therebetween is provided in an electrolyte (not shown) And the electrode tab 140 and the electrode lead 142 are formed on one side of the battery cell 100. [

The battery case 120 includes an upper case 121 facing the uppermost outermost electrode 115 of the electrode assembly 110 and a lower case 122 facing the lower outermost electrode 116 of the electrode assembly 110 The upper case 121 and the lower case 122 each have a distance d such that three variable extending portions 150 are not overlapped with each other about twice the width w of one variable extending portion 150, And is formed in the width direction with reference to the position where the electrode lead 142 is formed.

More specifically, the variable extension 150 is a folding type structure in which the battery case 120 is bent four times while forming a trough 153 and a floor 151 in a direction perpendicular to the electrode assembly 110, The folding type structure has a structure in which the electrode assembly 110 protrudes in a direction opposite to the direction in which the electrode assembly 110 is built with respect to the upper case surface 123 on which the variable extending portion 150 is not formed.

5 shows a form in which the variable extension 150 is extended when the battery cell is bent or bent.

Referring to FIG. 5, the variable extension 150 includes a trough 153 and a trough 151 in a direction perpendicular to the electrode assembly 110 when the battery case 120 is in an unstretched state The length of the surface of the battery case 120 facing the outer surface of the electrode assembly 110 corresponds to the outer surface length of the electrode assembly 110. However, The bending is released at an angle of? And? 'With respect to the hypothetical surface 160 parallel to the upper case surface 123 on which the variable extending portion 150 is not formed. Therefore, the variable stretching portion is stretched approximately by the projecting height of the variable extending portion 150, so that the length of the battery case 120 is increased.

FIG. 6 is a schematic view showing a bent shape of the battery cell 100 according to the present invention in order to more specifically explain the deformation of the variable extending portion 150 when the battery cell is bent or bent.

Referring to FIG. 6, the bent battery cell 100 'is folded in such a manner that both ends of the electrode assembly 110' bulge upward from the center thereof, and the battery case 120 ' 'Of the electrode assembly 110'. At this time, the variable extending portions 150 'on both sides of the upper case 121' are folded by a certain portion in accordance with the bending of the battery cell 100 'to deepen the crests and the floor, thereby reducing the length of the upper case 121' The flexible extension portions 150 'on both sides of the lower case 122' are formed in such a manner that the bent portions of one side are loosened according to the bending of the battery cell 100 ' ) Is increased by 102% to 140% in size.

That is, the flexible extending portion 150 'corresponds to the folded battery cell 100', and the extended portion of the battery case 120 'is formed by partially loosening the valley and the floor of the variable extending portion 150' The length of the battery case 120 'facing the outer surface of the electrode assembly 110' becomes longer than the outer surface length of the electrode assembly 110 ', and the compressed portion deepens the valley and the floor of the variable extension portion 150' , Unexpected wrinkles, folds, or cracks can be minimized in addition to the variable extending portion 150 'on the battery case 120'.

Although not shown, not only when the battery cell is bent or bent, but also when the electrode assembly is expanded inside the battery case, the variable stretching portion is stretched according to the volume of the electrode assembly as described above, , It is possible to secure the space of the cell case according to the expansion, and the stress of the electrode assembly due to the expansion can be relaxed. As a result, since the electrodes of the electrode assembly can be prevented from being short-circuited by the stress, the safety of the battery cell can be greatly improved.

7 and 8 are vertical cross-sectional views of a battery cell for illustrating another structure of the variable extending portion according to the present invention.

7, the battery cell 200 includes a positive electrode 212 and a negative electrode 214 which are laminated in a state in which a separator 213 is interposed therebetween. The electrode assembly 210 is impregnated with an electrolyte (not shown) And the electrode tab 240 and the electrode lead 242 are formed on one side of the battery cell 200. [

The battery case 220 includes an upper case 221 facing the uppermost outermost electrode 215 of the electrode assembly 210 and a lower case 222 facing the lower outermost electrode 216 of the electrode assembly 210 The upper case 221 and the lower case 222 are spaced apart from each other by a distance that does not overlap each other by three variable extending portions 250.

The variable extending portion 250 is a folding type structure in which the battery case 220 is disposed in the vertical direction with respect to the electrode assembly 210, The variable elongation unit 250 may be bent four times. However, since the variable elongation unit 250 is formed in a structure in which the electrode assembly 210 protrudes from the case surface on which the variable elongation unit 250 is not formed, (150).

8, the electrode assembly 310 having the structure in which the anode 312 and the cathode 314 are stacked in a state in which the separator 313 is interposed is formed in the battery cell 300 shown in FIG. 8 as an electrolyte (not shown) And an electrode tab 340 and an electrode lead 342 are formed on one side of the battery cell 300. The electrode tab 340 and the electrode lead 342 are formed on one side of the battery cell 300. [

The battery case 320 includes an upper case 321 facing the uppermost outermost electrode 315 of the electrode assembly 310 and a lower case 322 facing the lowermost outermost electrode 316 of the electrode assembly 310 The upper case 321 and the lower case 322 are spaced apart from each other by a distance that does not overlap each other by three variable extension portions 350.

The variable extending portion 350 is a folding type structure in which the battery case 320 is disposed in a vertical direction with respect to the electrode assembly 310, And the electrode assembly 310 is formed in a structure in which the electrode assembly 310 protrudes in a direction opposite to the direction in which the electrode assembly 310 is built with respect to the case surface on which the variable extension portion 350 is not formed 3 and the variable extension portions 150, 250 of FIG.

FIG. 9 is a plan view of a battery cell for illustrating another positional structure of the variable extending portion according to the present invention, and FIG. 10 is a sectional view of a battery cell for illustrating another forming direction of the variable extending portion according to the present invention. A top view is shown.

9, the battery cell 400 has a structure in which the electrode assembly 410 is embedded in the battery case 420 in a state of being impregnated with an electrolyte (not shown). On the battery case 420, The battery case 420 is formed in such a structure that the distance from the center of the battery case 420 toward the edge becomes wider at a distance at which the units 450 are not overlapped with each other.

10, the battery cell 500 has a structure in which the electrode assembly 510 is embedded in the battery case 520 in a state of being impregnated with an electrolyte (not shown), and on the battery case 520, The portions 550 are formed in the longitudinal direction of the battery case 520 on the basis of the position where the electrode leads 542 are formed at a distance that the portions 550 are not overlapped with each other by three folded structures.

As described above, the bending direction, the positional structure, and the forming directions of the variable elongating portions can be appropriately selected corresponding to the device in which the battery cell is mounted, and the battery cell including such variable elongating portions can be also deformed Unintentional creasing or folding can be prevented. Therefore, it is possible to effectively prevent the dielectric breakdown or electrolyte leakage due to the exposure of the metal layer due to the damage of the battery case.

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 (18)

The battery case includes an upper case facing the upper surface of the electrode assembly, and a lower case facing the lower surface of the electrode assembly, the battery case including an electrode assembly that can bend or flex according to the shape of the device on which the battery cell is mounted. However,
At least two variable elongation parts formed on the case surface corresponding to the upper surface of the electrode assembly in the upper case and the case surface corresponding to the lower surface of the electrode assembly in the lower case when the electrode assembly is bent or bent, ≪ / RTI &
Wherein the variable extending portions are spaced apart from each other and the mutually spaced intervals are 1 to 5 times as wide as the width of one variable extending portion and widen toward the edge from the center of the battery case. [2] The battery case according to claim 1, wherein the variable extension portion has a foldable structure in which the battery case is folded. The battery case according to claim 2, wherein the foldable structure is a structure in which the battery case is bent at least once so that the valleys and the floor are formed in a direction perpendicular to the electrode assembly. The battery case according to claim 2, wherein the foldable structure is formed in a lengthwise or widthwise direction of the battery case with respect to a site where the electrode terminal is to be located. The battery case according to claim 2, wherein the foldable structure is formed so as to protrude in a direction opposite to a direction in which the electrode assembly is housed based on an imaginary plane of the case surface on which the variable stretching portion is not formed. The battery case according to claim 2, wherein the foldable structure is formed so as to protrude in a direction in which the electrode assembly is housed based on a virtual plane of the case surface on which the variable stretching portion is not formed. The battery case according to claim 2, wherein the foldable structure is formed so as to protrude in a direction opposite to a direction in which the electrode assembly is housed with respect to an imaginary plane of the case surface on which the variable extension portion is not formed. The electrode assembly according to claim 1, wherein the variable extending portion has a length of a case surface facing the outer surface of the electrode assembly in an unstretched state corresponds to an outer surface length of the electrode assembly, Is longer than the outer surface length of the electrode assembly. The battery case according to claim 8, wherein the length of the case surface facing the outer surface of the electrode assembly in the elongated state is about 102% to 140% of the length of the outer surface of the electrode assembly. delete delete delete delete The battery case according to claim 1, wherein the battery case is a pouch-shaped case made of a laminate sheet including a metal layer and a resin layer. The battery case according to any one of claims 1 to 9 and 14; And
An electrode assembly capable of bending or bending depending on the shape of a device on which the battery cell is mounted;
Lt; / RTI >
The battery case includes an upper case facing the upper surface of the electrode assembly and a lower case facing the lower surface of the electrode assembly,
At least two variable elongation parts formed on the case surface corresponding to the upper surface of the electrode assembly in the upper case and the case surface corresponding to the lower surface of the electrode assembly in the lower case when the electrode assembly is bent or bent, ≪ / RTI &
Wherein the variable extending portions are spaced apart from each other, and the mutually spaced intervals are 1 to 5 times the width of one variable extending portion, widening toward the edge from the center of the battery case. A battery pack comprising the battery cell according to claim 15 as a unit cell. A device as claimed in claim 16 comprising a battery pack as a power source. 18. The device of claim 17, wherein the device is selected from the group consisting of a mobile phone, a portable computer, a smart phone, a smart pad, a tablet PC, a netbook, a LEV (Light Electronic Vehicle), an electric vehicle, a hybrid electric vehicle, a plug- ≪ / RTI >

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