KR101717197B1 - Flexible Battery Employed with a Plurality of Unit Cells - Google Patents

Abstract

The present invention relates to a battery capable of bending or flexing in correspondence with the shape of a device to be mounted,
Wherein at least two unit cells are mounted in the cell case in a planar arrangement,
Wherein a connection boundary portion capable of bending or bending can be formed between the unit cells while electrically connecting unit cells to each other.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a flexible battery having a plurality of unit cells,

The present invention relates to a flexible battery composed of a plurality of unit cells.

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, miniaturization is 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.

FIG. 1 schematically shows a general structure of a typical conventional pouch-type secondary battery as an exploded perspective view.

1, a pouch type secondary battery 10 includes a stacked unit cell 20 having a plurality of electrode taps 21 and 22 protruding therefrom, two stacked unit cells 20 each having two electrode taps 21 and 22 connected to electrode taps 21 and 22, And a battery case 40 having a structure in which the stacked unit cells 20 are received and sealed such that 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 into which the stacked unit cells 20 can be placed and a stacked unit cell 20 And an upper case 43 for sealing the upper case 43. The upper case 43 and the lower case 42 are thermally welded together with the stacked unit cell 20 built therein so that the upper end sealing portion 44 and the side sealing portions 45 and 46 and the lower end sealing portion 47 ).

1 shows a pouch-shaped battery cell having a structure in which electrode terminals having a structure in which electrode tabs and electrode leads are connected together at one end, a pouch type battery cell having a structure in which electrode terminals are formed at one end and at the other end, respectively The battery cell and the like can also be manufactured by the same method.

Although FIG. 1 shows a pouch-shaped battery cell using stacked unit cells, it is needless to say that the unit cell of the present invention can also be manufactured by the above-described method even when a wound-type or jelly-roll type unit cell is used.

As shown in Fig. 1, 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 for changing the shape of the outer casing while minimizing the influence on the unit cells built in the pouch type secondary battery.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and the technical problems required from the past.

Specifically, the object of the present invention can be flexibly bent or bent in correspondence with various designs of devices or flexible devices to which the battery is mounted, without cracking or detachment due to weakening of the adhesive force of the active material coating layer, And to provide a battery capable of precisely responding to the shape of a device.

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

A battery capable of being bent or bent according to the shape of a mounted device,

Wherein at least two unit cells are mounted in the cell case in a planar arrangement,

And an interfacial boundary portion capable of bending or bending can be formed between the unit cells while electrically connecting unit cells to each other.

The inventors of the present application have found that when two or more unit cells are arranged in a plane and the unit cells are electrically connected to each other and the unit cells are electrically connected to each other, Which flexibly bends or flexes in response to various design devices or flexible devices to which the battery is mounted, unlike a battery composed of a single unit cell, a crack occurs in the active material coating layer when the battery is bent, It is possible to precisely cope with the shape of the device.

The arrangement of the unit cell and the connection boundary is not particularly limited. Considering the case where a cell including a unit cell is embedded in a device, a connection boundary exists in a portion where a large amount of bending or bending occurs, It is preferable that the unit cells are located in the portion.

At this time, the arrangement of the unit cells may be determined according to necessity by dividing the direction in which the battery is bent or bent in a largely longitudinal direction and a width direction, and is not limited, but may be bent in two or more directions, When the cells are arranged in both the longitudinal direction and the width direction, it is possible to flexibly cope with the deformation direction of the device regardless of the direction in which the unit cells are arranged in one direction so that the cells can be bent or bent in one direction , And may have a shape that is reduced in both the longitudinal direction and the width direction, so that it is possible to more precisely cope with the shape of the device.

Accordingly, the battery may include two or more unit cells arranged in the longitudinal direction and two or more unit cells arranged in the width direction so that the battery may be bent or bent in the longitudinal direction and the width direction.

In addition, when unit cells adjacent to each other are arranged at positions where one connection boundary portion is bent or bent due to an arrangement structure and lengths of mutually adjacent unit cells and connection boundary portions do not coincide with each other, Cracks may be generated in the active material layer. The arrangement and lengths of the adjacent unit cells and the connecting boundary portions may coincide with each other so that the battery can easily bend or bend without leaving the active material.

Here, the longitudinal direction means the electrode terminal formation direction in the battery, and the width direction means the direction perpendicular thereto.

Furthermore, since the battery mounted on the device is often bent or bent at the central portion, the width of the connection boundary portion located at the center of the battery is large, The width of the connection boundary portion located is preferably small in terms of capacity of the battery.

Therefore, the width of the connection boundary, which is the interval between adjacent unit cells, may be reduced toward the edge from the center of the cell, and may be reduced to a certain extent in the range of 50% to 95% .

The connection boundary portion may be a bus bar connecting the electrode terminals of the unit cells or the electrode terminals.

The bus bar may be made of a metal material, for example, a metal such as Zn, Cu, Ni, Al, or the like, May be formed in a plate-like structure for minimizing an increase in the volume of the module

When the connection boundary portion establishes an electrical connection between the unit cells, the electrical connection may be a serial connection or a parallel connection. In case of parallel connection, a separate electrical connection may be required depending on the arrangement direction of the unit cells. In particular, when the electrode terminals are directly connected to each other, the unit cells in the center of the cell are connected to the electrode terminals There may be a separate electrical connection to be connected.

In one specific example, an insulating material may be coated on the one or both sides of the connection boundary to prevent short-circuiting and to improve safety, or an insulating tape may be attached.

The unit cell may include a positive electrode and a negative electrode coated with an active material on a current collector, and a separator interposed between the positive electrode and the negative electrode.

The type of the unit cell is not limited. Specifically, the unit cell includes a stacked cell structure in which a plurality of positive electrodes and negative electrodes cut in a predetermined size unit are sequentially stacked with a separator interposed therebetween, or a stacked cell structure in which an anode, A folded cell structure having a structure in which a winding core is wound around a winding core in a state where a positive electrode and a negative electrode are stacked with a separator interposed therebetween, and a bi- And a stack / folding cell structure of one structure or a stack / folding cell structure of one structure or two or more. In this case, the anode, the separator, the cathode of the stack unit cell, or the anode, separator, cathode, or stack / folding unit cell of the stacked unit cell may be laminated.

Here, the bi-cell has a stacked structure in which cells of the same kind are located on both sides, and a cell having a stack structure of, for example, a cell including a cathode-separator-cathode- separator- anode or cathode- separator- anode- to be. The pull cells have a stacked structure in which different types of electrodes are located on both sides of the cell, and are, for example, cells made of a cathode-separator-cathode.

The size of the unit cells is not limited and can be variously determined, and may be determined in consideration of the number of bending or bending depending on the type of the device on which the battery is mounted. Specifically, the smaller the size of the unit cells, the narrower the intervals at which the connection boundary is formed, and thus the more flexible unit cells can be formed, and the number of times the unit cells are bent or bent is required. And the number of times of bending or bending is required to be small, the size of the unit cells can be increased to more precisely cope with the device.

However, at this time, the sum of the area of the unit cells may be 50% to 95%, and more specifically, 70% to 90% based on the total area of the inside of the cell case. If the sum of the area of the unit cells is less than 50% based on the total area of the inside of the cell case, there is a problem that the size of the battery becomes very large in order to obtain a desired capacity by reducing the capacity of the battery And if the sum of the area of the unit cells exceeds 95% based on the total area of the inside of the cell case, the area of the connecting boundary may be reduced to prevent the battery from bending or bending easily, Stress is applied to the cell so that the electrode mixture layer in the unit cell around the connection boundary portion can easily be removed, which is not preferable.

On the other hand, since the unit cells are fixed by the cell case, movement in the cell case can be prevented.

Specifically, it is possible to minimize the space other than the mounting space of the unit cells in the cell case, or a separate plastic fixing member formed at the upper or lower end of the cell case for fixing the unit cells, A protruding strip formed in the cell case corresponding to the interface, and the like.

The cell case may include an upper case in contact with the upper surface of the unit cells and a lower case in contact with the lower surface of the unit case. At least one of the upper case and the lower case may have a recessed portion, have. Such an indentation is a portion for forming a clearance surface in the cell case, and enlarges the surface area of a portion where the cell case is bent or bent, thereby dispersing the stress applied to the cell case when the cell is bent or bent, The depth of the depressed portion may be 3 to 40% of the average thickness of the unit cells.

More specifically, the cell case may be a pouch type case made of a laminate sheet including a resin layer and a metal layer with a flexible characteristic of a battery that can be easily mounted in devices of various designs.

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.

As described above, the battery can be bent or bent according to the shape of the device on which the battery is mounted due to the flexible connection boundary portion and the variable cell case. The shape of the battery is not limited, and may vary depending on the type of device . Specifically, the device may be mounted on the device in a form that is not bent or bent, may be flexibly responded to the shape modification of the device, may be mounted in a bent or bent shape when mounted on the device, May be mounted in a bent shape more than once.

The present invention also provides a battery pack including at least two battery cells, and the device includes the battery pack as a power source.

The device may be one selected from a cell 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-in hybrid electric vehicle, . The structure of these devices and their fabrication methods are well known in the art, and a detailed description thereof will be omitted herein.

As described above, since the battery according to the present invention is constituted by a plurality of unit cells and can be bent or bent, it is possible to prevent cracks of the active material coating layer, It is possible to flex or bend flexibly corresponding to various designs of devices or flexible devices to which the battery is mounted without the problem of loss of function.

1 is an exploded perspective view of a typical conventional pouch type secondary battery;
2 is a plan view and a side view of a cell interior according to one embodiment of the present invention;
3 is a plan view of a cell interior showing a structure in which unit cells according to another embodiment of the present invention are arranged in the longitudinal direction and the width direction;
FIG. 4 is a plan view of a cell interior showing a structure in which the width of a connection boundary portion decreases from the center to the edge of the battery according to another embodiment of the present invention; FIG.
5 is a side view of the inside of a battery in which a recess is formed in a cell case according to another embodiment of the present invention;
FIG. 6 is a schematic view showing a shape in which the battery of FIG. 2 is bent with reference to a connection boundary portion. FIG.

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.

2 to 4 are plan views of the batteries 100, 200, and 300 according to the embodiment of the present invention.

Referring to FIG. 2, the cell 100 is mounted in the cell case 130 in a state where the unit cells 120 are arranged in a plane in the longitudinal direction, and between the unit cells 120, The unit cells 120 are electrically connected to each other and have a plurality of connection boundaries 110 that are bent or bent at a predetermined width. At this time, in order to easily bend or bend the battery and to obtain a desired battery capacity, the sum of the areas of the unit cells 120 is 50% to 95% of the total area of the inside of the cell case 130 And in particular can be from 70% to 90%.

3, the battery 200 can be folded or bent in the width direction (b) as well as in the length direction (a) of the battery 200, And at least two unit cells 220 arranged in the longitudinal direction a and a plurality of unit cells 220 arranged in the width direction b in the unit cell 220, 220 are electrically connected to each other and are formed in a longitudinal direction connecting boundary portions 210a and a width direction connecting boundary portions 210b capable of bending or bending. At this time, the structure and length of the adjacent unit cells 220 and the connection boundary portions 210a and 210b are mutually coincident.

Referring to FIG. 4, unlike FIG. 2 in which the width of the connection boundary portion, which is the interval between adjacent adjacent unit cells, is constant, the cell 300 is connected to the unit cell 320, The widths 311a and 311b of the boundary portions are reduced toward the edge of the battery 300. The widths of the boundaries 311a and 311b are uniformly reduced in the range of 50% to 95% And connection border portions 310 having a connection border width 311b of a small size are formed. .

Meanwhile, the cell cases 130, 230, and 330 shown in FIGS. 2 to 4 may have a weak structure due to stress when the cells 100, 200, and 300 are bent or bent. FIG. FIG.

5, a plurality of unit cells 420 are mounted in a cell case 430 in a state that they are arranged in a plane, and a unit cell 420 is disposed between the unit cells 420, (420) are connected to each other to form a connection boundary (410) which can be bent or bent. At least one of the upper case and the lower case has a portion corresponding to the connection boundary portions 410. The upper case and the lower case have the same shape, And the recessed portions 431 are formed in the recessed portion 431. As shown in FIG. At this time, the depth 431a of the indentation may be 3 to 40% of the average thickness 431b of the unit cell 420. These indentations 431 further form a clearance surface in the cell case 430 corresponding to the connection boundary 410 where the battery 400 is bent or curved to enlarge the surface area, It is possible to secure the safety by dispersing the stress applied to the cell case 430 when bent or bent.

In order for these cells to exhibit a bent or curved shape with respect to the connection boundary portions, FIG. 6 shows, as an example, a shape in which the battery 100 of FIG. 2 is bent along the connection boundary portions 110, (140). ≪ / RTI >

2 and 6, the battery 100 including the unit cells 120 having the connection boundary portions 110 can be formed at a portion (A, B, C, D) where the connection boundary portion exists Four bends 141, 142, 143 and 144 are formed, resulting in the bent battery 140. The number of times of bending and the number of bending operations are not limited to those shown in Fig. 6, and can be freely selected depending on the shape and purpose of the device to which the battery is mounted.

Although not shown in the drawing, when mounting a plurality of unit cells in the cell case, the unit cells may be fixed by the cell case to prevent a short circuit due to movement of the unit cells, A space other than the mounting space of the unit cells may be minimized inside the cell case or a separate plastic fixing member formed at the upper or lower end of the cell case for fixing the unit cells, And a protruding strip formed in the cell case corresponding to the protruding strip.

As described with reference to the drawings, a battery according to the present invention is mounted in a cell case in a state where two or more unit cells are arranged in a plane, and between the unit cells, It is possible to design various bending or flexing shapes without causing problems such as cracking of the active material coating layer or loss of function of the battery due to detachment due to weakening of the adhesive force Therefore, it can flexibly and precisely cope with various forms according to various design devices or flexible devices to which the batteries are mounted.

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 (20)

A battery capable of being bent or bent according to the shape of a mounted device,
At least two unit cells are mounted in the interior of the cell case in a planar arrangement;
Between the unit cells, an interconnection boundary is formed which can be bent or bent while electrically connecting the unit cells.
The cell case includes an upper case in contact with the upper surface of the unit cells, and a lower case in contact with the lower surface. The upper case and the lower case are formed with depressed portions depressed corresponding to the connection boundary.
The width of the connection boundary portion, which is the interval between unit cells adjacent to each other, decreases toward the edge from the center of the cell,
And is uniformly reduced in the range of 50% to 95% based on the largest connection border width. The battery according to claim 1, wherein the battery includes two or more unit cells arranged in the longitudinal direction and two or more unit cells arranged in the width direction so that the battery can be bent or bent in the longitudinal direction and the width direction Battery. The battery according to claim 2, wherein the arrangement and lengths of the adjacent unit cells and the connecting boundary portions are mutually coincident with each other. delete delete The battery according to claim 1, wherein the connection boundary portion is a bus bar connecting the electrode terminals of the unit cells or the electrode terminals. The battery according to claim 1, wherein an insulating material is coated on one or both sides of the connection boundary portion. The battery according to claim 1, wherein an insulation tape is attached to one or both surfaces of the connection boundary portion. The battery according to claim 1, wherein the unit cell comprises a positive electrode and a negative electrode coated with an active material on a current collector, and a separator interposed between the positive electrode and the negative electrode. The battery according to claim 9, wherein the unit cell comprises one or more selected from the group consisting of a stacked cell structure, a folding cell structure, and a stack / folding cell structure. The battery according to claim 1, wherein the sum of the area of the unit cells in a plane is 50% to 95% based on the total area of the inside of the cell case. 12. The battery according to claim 11, wherein the sum of the area of the unit cells in a plane is 70% to 90% based on the total area of the inside of the cell case. The battery according to claim 1, wherein the unit cells are fixed by a cell case. delete The battery according to claim 1, wherein the depth of the indent is 3 to 40% of the average thickness of the unit cell. The battery according to claim 1, wherein the cell case is a pouch-shaped case of a laminate sheet including a resin layer and a metal layer. The battery according to claim 1, wherein the battery is a lithium secondary battery. A battery pack comprising at least two batteries according to claim 1. A device according to claim 18, comprising the battery pack as a power source. 20. The method of claim 19, wherein the device is selected from the group consisting of a mobile phone, a portable computer, a smart phone, a tablet PC, a smart pad, a netbook, a LEV (Light Electronic Vehicle), an electric vehicle, a hybrid electric vehicle, ≪ / RTI > device.

Images