KR20150128063A - Electrode Assembly Having Alternatively-arranged Noncoating Parts and Coating Parts and Flexible Battery Cell Comprising the Same - Google Patents

Abstract

The present invention relates to an electrode assembly, which comprises at least one positive plate and at least one negative plate which are stacked by which a separator is interposed in between, wherein at least one among the positive plates and the negative plates has a structure alternatively arranged with: a plurality of coating parts coated with electrode active materials on one or both sides of a current collector; and a plurality of uncoating parts uncoated with the electrode active materials. Therefore, provided is an electrode assembly which can be bent or curved without deintercalation of the electrode active materials in accordance with a conformation of the device which is to be mounted.

Description

[0001] The present invention relates to a flexible electrode assembly including a non-coated portion and a coating portion arranged in an alternating arrangement, and a battery cell including the flexible electrode assembly.

The present invention relates to a flexible electrode assembly including an alternating arrangement of a non-conductive portion and a coating portion, and a battery cell including the flexible electrode assembly.

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 to provide an appropriate 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 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 ).

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.

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

On the other hand, 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 a battery cell or a battery pack having a rectangular parallelepiped shape can not be built in a space inside the device. In recent years, Flexible characteristics of a battery that can be easily mounted in a device are required.

However, in the case of a device designed to have a curved portion or a flexible or bendable device, the electrode assembly of the stored battery cell is bent at a certain angle or more to cause cracks in the active material coating layer, The adhesive strength between the adhesive layer and the adhesive layer is weakened.

Therefore, there is a high need for a technique for changing the shape of the electrode assembly and the outer sheath in accordance with the built-in device shape without removing the active material.

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 the electrode has a structure in which a plurality of coating portions coated with the electrode active material and a plurality of uncoated portions uncoated with the electrode active material are alternately arranged, It has been confirmed that cracks are formed in the active material coating layer or the coating layer is not removed from the current collector even when the material is bent over a certain angle and that the shape of the battery can be flexibly deformed corresponding to devices of various designs. It came.

According to an aspect of the present invention, there is provided an electrode assembly comprising:

An electrode assembly capable of bending or flexing corresponding to the shape of a device to be mounted,

Wherein the electrode assembly includes at least one positive electrode plate and at least one negative electrode plate laminated in a state in which a separator is interposed,

Wherein at least one of the positive electrode plate and the negative electrode plate has a structure in which a plurality of coating portions coated with an electrode active material on one surface or both surfaces of a current collector and a plurality of uncoated portions coated with an electrode active material are alternately arranged.

The inventors of the present application have found that when the active material layer and the non-active portions are formed on at least one surface of the current collector in regular or irregularly alternating arrangement, a certain bendable region is formed corresponding to the stress of the electrode assembly caused by deformation of the battery cell , It was confirmed that cracks and tearing of the electrode active material were prevented by dispersing the stress.

As described above, the alternating arrangement structure of the coating portions and the non-coated portions may be formed on one side or both sides of the current collector, and is not necessarily limited to both sides. However, when the battery is bent or bent, In one specific example, it may be formed on both sides. In this case, the structure may be such that the alternate arrangement structure of one side of the both sides and the alternate arrangement structure of the other side of the both sides coincide with each other. If the electrode assembly does not match, the electrode assembly may be folded or bent at one side, but may correspond to the coated portion at the other side, so that the electrode active material may be separated from the electrode corresponding to the coated portion at the time of bending or bending Having said, it is not desirable.

Similarly, the alternating arrangement structure of the coating portions and the non-coated portions may be formed in the positive electrode plate and the negative electrode plate, respectively. In this case, if the alternating arrangement structure of the positive electrode plate and the negative electrode plate is not coincident with each other, The electrode active material may be desorbed. The alternating arrangement structure of the positive electrode plate and the alternate arrangement structure of the negative electrode plate may be mutually coincident.

In addition, in the case where a certain stress is applied to the electrode plate, the most bent or curved portion is the center of the electrode and requires a wider range of uncoated portions. Thus, in one specific example, May be a structure in which the width of the uncoated portion decreases toward the edge from the center of the electrode plate, and in particular, it may be a structure that decreases constantly in the range of 50% to 95% based on the largest uncoated portion width.

In one specific example, the area of the uncoated portions may range from 10% to 50% of the total area of the positive or negative electrode plate. If the area of the uncoated portions is less than 10%, it is difficult to bend or bend the electrode assembly to a desired degree without detaching the electrode active material. If the area is more than 50%, the battery capacity exerted from one electrode decreases, There is a problem that the size of the electrode assembly becomes very large in order to obtain the electrode assembly, and the external stress can concentrate only on the thin current collector, and the electrode active material can be easily removed or cut.

In the case where the current collector has a plurality of coating portions coated with the electrode active material and a plurality of uncoated portions uncoated with the electrode active material are alternately arranged, the non-coated portions, which are not coated with the electrode active material, , It may be bent or warped in response to external stress, but it is structurally weak and can be easily cut when external pressure is applied at a certain angle. Therefore, the present invention also provides a configuration for solving this.

In one example, the above effect can be achieved by making the thickness of the current collector located in the non-coated portion where the electrode active material is not coated relatively thicker than the thickness of the current collector located in the coated portion coated with the electrode active material.

In this case, the thickness of the current collector located at the non-coated portion may be 5% to 200% greater than the thickness of the current collector located at the non-coated portion, more specifically 20% to 180% It may be a thicker structure. When the thickness of the current collector located at the non-coated portion is thicker than 5% of the thickness of the current collector located at the coated portion, it is difficult to achieve the effect of firmly fixing the non-coated portion, When the thickness of the current collector located at the non-coated portion is greater than 200% of the thickness of the current collector located at the coated portion, the current collector located at the non-coated portion is excessively thick, so that it is difficult to bend or bend to a desired extent.

In another example, the above problem can be solved by forming one or more protruding strips on the current collector located in the non-coated portion where the active material is not coated. Here, the protruding strip generally means a protrusion protruding from a uniform surface, which means that the protrusion forms a line.

At this time, the protruding strips may have one or more lines, and in the case of two or more protruding strips, the protruding strips may be parallel or perpendicular to each other, or may have a constant angle. In addition, the protruding strip may be linear or curved, and more particularly, may be formed in a direction perpendicular to the coating portion, or may have a lattice pattern, but the present invention is not limited thereto . Here, the direction perpendicular to the coating portion means a direction parallel to the direction in which the coating portion coated with the electrode active material on the current collector and the non-coated portions are alternately arranged.

The height of the protruding strip may be 5% to 100% of the thickness of the active material coating layer. Here, the thickness of the active material coating layer refers to the length measured vertically from the surface of the current collector, and the height of the protruding strip refers to the length of the protruding strip measured vertically from the surface of the current collector corresponding to the non- .

If the height of the protruding strip is less than 5% of the thickness of the active material coating layer, it is difficult for the current collector corresponding to the non-coated portion to be hard to be solidified and the intended effect is difficult to achieve. If the height exceeds 100% of the thickness of the active material coating layer, It is difficult to bend or bend the electrode, and the protruding strip protrudes from the active material coating layer, thereby damaging the separator or the pouch containing the electrode assembly, which is not preferable.

 On the other hand, in another example, the above problem can be solved by coating an insulating material on one surface or both surfaces or attaching an insulating tape. At this time, the insulating tape or insulating material may be, for example, flexible plastic or thermoplastic resin, but is not limited thereto.

As described above, when the thickness of the current collector located in the non-coated portion is made thicker, the protruding strip having a predetermined shape is formed, or when the insulating film or the insulating tape is attached to the non-coated portion, the flexibility It is possible to provide an electrode assembly in which safety is improved by supplementing a structurally weak ignorance region while securing a higher flexibility than when the electrode active material is entirely applied to the current collector.

The present invention also provides a battery cell in which the electrode assembly is embedded in a battery case. The battery cell may be a rechargeable lithium secondary battery which is formed by impregnating and sealing an electrode assembly in a battery case with an electrolyte.

The battery case may be a battery case of a laminate sheet including a resin layer and a metal layer and having flexibility characteristics of a battery that can be easily mounted in devices of various designs, It can be bent or bent.

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. Therefore, as a method for improving the adhesion with the metal layer, more specifically, an adhesive layer is additionally provided 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 electrode assembly embedded in the cell case, which is embedded in the electrolyte solution in a state of being impregnated with the electrolytic solution, is not particularly limited as long as it is a plate-like structure in which a plurality of electrode tabs are connected to form an anode and a cathode. However, It is preferable that a stacked electrode assembly in which a plurality of positive electrodes and negative electrodes cut in a predetermined size unit are sequentially stacked with a separator interposed therebetween, A stack / folding type electrode assembly in which a Bi-cell or a full cell stacked with a separator interposed therebetween is wound up as a separation film.

At this time, the bi-cell has a stacked structure in which the cells of the same kind are located on both sides, for example, a cell having a stack structure such as a cell comprising 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 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 present invention also provides a device including the battery pack as a power source, wherein the device is used in a mobile phone, a portable computer, a smart phone, a tablet PC, a smart pad, a netbook, a LEV (Light Electronic Vehicle) A hybrid electric vehicle, a plug-in hybrid electric vehicle, and a power storage device.

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 electrode assembly according to the present invention is based on a specific structure in which the coating part coated with the active material and the uncoated non-coated parts are alternately arranged on the current collector as described above, It is possible to more precisely cope with various designs of devices or flexible devices in which the battery cells can be bent and accordingly the battery cells are mounted.

1 is an exploded perspective view of a typical conventional pouch type secondary battery;
Figure 2 is a side view of a typical representative electrode;
3 is a top view and a side view of an electrode according to one embodiment of the present invention;
4 is a plan view of an electrode according to another embodiment of the present invention, in which the width of the uncoated portion is reduced toward the edge from the center of the electrode plate;
FIG. 5 is a side view of an electrode according to another embodiment of the present invention, in which the thickness of the current collector located at the non-coated portion is thicker than the thickness of the current collector located at the coated portion;
FIG. 6A is a plan view and a cross-sectional view of an electrode in which a protruding strip is formed on a current collector corresponding to a non-printed portion according to another embodiment of the present invention; FIG.
6B is a plan view of an electrode in which a grid pattern protruding strip is formed on a current collector corresponding to a non-coated portion 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.

In order to compare the structure of the electrode according to the present invention, FIG. 2 shows a side view of a conventional representative electrode 100.

Referring to FIG. 2, the electrode 100 has a structure in which the electrode active material 120 is applied to the current collector 110.

On the other hand, in order to prevent the active material from cracking or tearing due to deformation of the electrode assembly, the electrode according to the present invention includes a coating portion coated with an active material layer on both sides of the current collector and a non- Lt; / RTI >

3 is a schematic diagram of an electrode 200 according to an embodiment of the present invention.

3, the electrode 200 includes a plurality of coating portions 212 coated with an electrode active material 220 on a current collector 210, a plurality of uncoated portions 211 not coated with the electrode active material 220, Are alternately arranged at regular intervals. At this time, the area of the non-coated portions 211 may be in the range of 10% to 50% of the total area of the electrode 200.

The electrode active material 220 is coated on both sides of the current collector 210. In this case, the electrode active material 220 has a structure in which the alternating array structure on one side and the alternate array structure on the other side are coincident with each other. Although only the electrodes having the alternate arrangement structure are formed on both sides of the electrode are shown in the drawing, it is needless to say that the alternate arrangement structure may be formed on only one side of the electrode.

4 shows an electrode 300 having a structure in which the width of the uncoated portion decreases from the center of the electrode plate toward the edge in consideration of the point where the most bent or curved portion is the center of the electrode when a constant stress is applied to the electrode plate .

4, unlike the electrode 200 of FIG. 3, in which the width of the non-coated portion, which is the gap between the adjacent coated portions, is uniform, The widths 311a and 311b are reduced toward the edges from the center of the electrode plate. The widths of the electrode plates 311a and 311b are uniformly reduced from 50% to 95% based on the largest uncooled width 311a, And a sub-width 311b.

Meanwhile, the electrodes 200 and 300 of FIGS. 3 and 4 can be easily bent or bent without detaching the electrode active material according to the deformation of the electrode assembly, while the non-conductive parts 211 and 311 are formed of a thin metal plate The structure may be coated with an insulating material (not shown) or an insulating tape (not shown) to improve the strength of the non-printed portions 211 and 311.

In addition, as another method for improving the strength of the unprinted portions, FIGS. 5 to 6B show electrodes 400, 500, and 600 of a structure that can solve the above problems.

5A and 5B illustrate an electrode 400 having a structure in which the thickness of the current collector located at the non-coated portion is thicker than the thickness of the current collector located at the coated portion. FIGS. 6A and 6B illustrate an electrode 400 And electrodes 500 and 600 on which protruding strips are formed.

5, the electrode 400 is different from the electrode 200 of FIG. 3 in that the thickness 410a of the current collector 410 located in the non-coated portion, which is not coated with the electrode active material 420, And is thicker than the thickness 410b of the current collector 410 located in the coated portion. At this time, the thickness 410a of the collector located at the non-coated portion may be 5% to 200% greater than the thickness of the collector 410 located at the non-coated portion than the thickness 410b of the collector located at the coated portion. 20% to 180% thicker structure.

6A and 6B, in comparison with the electrode 200 of FIG. 3, a plurality of protruding strips (not shown) are formed on the current collectors 510 and 610 located in the uncoated portions 511 and 611, 530, and 630 are formed.

6B, the protruding strip 530 has four protruding strips 530 formed parallel to each other. Referring to FIG. 6B, the protruding strip 630 has six protrusions Shaped strips 630 are formed in a grid pattern at a constant angle. However, the shapes of the protruding strips 530 and 630 shown in the drawings are merely examples, and the protruding strips may be linear or curved, but are not limited thereto.

As described above with reference to the drawings, at least one of the positive electrode plate and the negative electrode plate of the electrode assembly according to the present invention includes a plurality of coating portions coated with an electrode active material on one surface or both surfaces of the current collector, and a plurality of uncoated portions The electrode assembly and the battery including the electrode assembly can be bent or bent without detaching the electrode active material. In order to improve the strength of the non-molded portion, the thickness of the non-molded portion can be adjusted, It is possible to increase the lifetime of the battery cell ultimately embedded in the flexible device.

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)

An electrode assembly capable of bending or flexing corresponding to the shape of a device to be mounted,
Wherein the electrode assembly includes at least one positive electrode plate and at least one negative electrode plate stacked with a separator interposed therebetween,
Wherein at least one of the positive electrode plate and the negative electrode plate has a structure in which a plurality of coating portions coated with an electrode active material on one surface or both surfaces of the current collector and a plurality of uncoated portions coated with an electrode active material are alternately arranged. . 2. The electrode assembly according to claim 1, wherein the alternating arrangement structure of the coating portions and the non-coated portions is formed on both sides of the current collector, and the alternating arrangement structure of the one surface and the alternating arrangement structure of the other surface are mutually coincident with each other. . The electrode assembly according to claim 1, wherein the alternating arrangement structure of the coating portions and the non-coated portions is formed on the positive electrode plate and the negative electrode plate, respectively, and the alternating arrangement structure of the positive electrode plates and the alternating arrangement structure of the negative electrode plates are mutually coincident. The electrode assembly according to claim 1, wherein the width of the uncoated portion, which is a gap between the adjacent coating portions, is reduced toward the edge from the center of the electrode plate. The electrode assembly of claim 4, wherein the electrode assembly is uniformly reduced in the range of 50% to 95% based on the largest uncoated width. The electrode assembly according to claim 1, wherein an insulating material is coated on one or both sides of the non-coated portion. The electrode assembly according to claim 1, wherein an insulating tape is attached to one surface or both surfaces of the non-coated portion. The electrode assembly according to claim 1, wherein a thickness of the current collector located at the non-coated portion is relatively thicker than a thickness of the current collector located at the coated portion. The electrode assembly according to claim 8, wherein the thickness of the current collector is 5 to 200% greater than the thickness of the current collector located in the coating portion. The electrode assembly according to claim 1, wherein at least one protruding strip is formed on the current collector located at the non-coated portion. 11. The electrode assembly of claim 10, wherein the protruding strips are formed in a direction perpendicular to the coating. 11. The electrode assembly of claim 10, wherein at least two protruding strips are formed and have a lattice pattern. The electrode assembly according to claim 1, wherein the area of the non-coated portions is in a range of 10% to 50% of the total area of the positive electrode plate or the negative electrode plate. The electrode assembly of claim 1, wherein the electrode assembly is a stacked or stacked / folded structure. 15. A battery cell comprising an electrode assembly according to any one of claims 1 to 14 embedded in a battery case and impregnated with an electrolyte and sealed. 16. The battery cell according to claim 15, wherein the battery case is a battery case of a laminate sheet including a resin layer and a metal layer. The battery cell according to claim 15, wherein the battery cell is a lithium secondary battery. A battery pack comprising at least two battery cells according to claim 15. 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.

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