KR20170070452A - Battery Cell Having Zigzag-Type Electrode Assembly - Google Patents

Abstract

The present invention provides a battery cell in which an electrode assembly having a structure bent in a zigzag shape is embedded in a battery case, the electrode assembly comprising a positive electrode sheet and a negative electrode sheet, and a first separator interposed between the positive electrode sheet and the negative electrode sheet (N is an integer equal to or greater than 2) and the n-th cathode flat portion faces the (n + 1) th anode flat portion, and the n-th cathode flat portion (H _n ) of the n-th anode flat portion and the (n + 1) -th cathode flat portion are bent in a zigzag form along the longitudinal direction (L) of the sheet so as to face the And the size of the n-th cathode plane portion H _{n '} and the size of the ( _{n + 1} ) th cathode plane portion H _{n + 1'} are different from each other, The tab protrudes toward the top of the battery case And it provides a battery cell that is built so that it is perpendicular to the bottom surface of the anode and cathode flat plane portion added the battery case.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a battery cell Having Zigzag-Type Electrode Assembly including a zigzag-

The present invention relates to a battery cell including a jig jig-shaped electrode assembly.

2. Description of the Related Art [0002] In recent years, with the development of technology and demand for electric devices, the demand for secondary batteries is also rapidly increasing. With the emergence of devices of various designs including slim type or curved surface structures, .

In this regard, since the conventional secondary battery has a simple hexahedral structure, a mismatch occurs in the shape of a curved or circular device, so that a quadrangular or quadrangular quadrangular- When a battery is used, there is a problem that a loss occurs in terms of capacity in terms of a lost volume.

On the other hand, the lithium secondary battery includes a cylindrical battery and a prismatic battery in which an electrode assembly is embedded in a cylindrical or rectangular metal can according to the shape of the battery case, and a pouch type battery in which an electrode assembly is embedded in a pouch- .

The electrode assembly includes a positive electrode / separator / negative electrode laminate structure and a charge / dischargeable power generation device. The electrode assembly is divided into a jelly-roll type in which a separator is interposed between a positive electrode and a negative electrode coated with an active material, Folded stacked unit cells in which stacked unit cells such as stacked cells, bi-cells, and pull cells stacked in this order with an anode and a cathode interposed therebetween are stacked in a stacked / folded and stacked unit cells Stacked type in which the separator is interposed therebetween.

Generally, in the case of a cylindrical battery, a jelly-roll type electrode assembly is used in consideration of the overall shape and capacity, and the jelly-roll type electrode assembly is high in volume because of its easy manufacturing method and volume. It is possible to reduce the dead space.

However, in the case of manufacturing a cylindrical battery having a small diameter, the resistance applied to the wound jelly-roll type electrode assembly increases, and it is not easy to weld the electrode tab to the bottom surface of the battery case, have.

Therefore, when reflecting the trend of development of various types of devices, it is possible to exhibit a high capacity by reducing the dead space without using a jelly-roll type electrode assembly in a cylindrical battery, and a need for a secondary battery having a simple manufacturing method is high to be.

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 using a battery cell in which an electrode assembly having a structure bent in a zigzag form in a cylindrical battery is used as described later, It is possible to provide a high capacity battery for a multifunctional miniaturized product because it is possible to prevent the problem of increase in resistance due to winding of the electrode assembly, .

In addition, since the electrode assembly is embedded in a cylindrical can made of a metal material, durability is improved, and occurrence of fire and ignition due to an impact applied from the outside can be minimized. Therefore, it is possible to provide a secondary battery having improved safety as well as increased capacity of the secondary battery.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a battery cell in which an electrode assembly having a structure bent in a zigzag shape is embedded in a battery case, the electrode assembly including a positive electrode sheet and a negative electrode sheet, The positive electrode sheet and the negative electrode sheet are constituted by the first separator interposed between the negative electrode sheets, and the negative electrode plate portion and the negative electrode sheet portion face each other at the same end, (n + 1) -th cathode flat portion is bent in a zigzag shape along the longitudinal direction (L) of the sheet,

Wherein n anode plane portion size (H _n) and the n + 1 positive flat portion, the size of (H _{n + 1)} different from one another, wherein the n cathode planar portion size (H _{n ')} and the n + 1 negative plane (H _{n + 1 '} ) are different from each other, and the electrode tab is protruded toward the upper part of the battery case, and the anode flat part and the cathode flat part are built so as to be perpendicular to the lower end surface of the battery case .

As described above, the battery cell according to the present invention has a structure in which the electrode assembly is folded in a zigzag shape, and the jell-roll type electrode assembly is conventionally used in the cylindrical battery case, It is possible to solve the problem of separation of the composite layer or increase in internal resistance. In this case, the cylindrical battery case having a small diameter may increase the problem of increased internal resistance. In such a case, it may be more preferable to use a zigzag-shaped electrode assembly according to the present invention.

Further, since the reduction in the volume occupied by the electrode assembly in the battery case is minimized even if the jelly-roll type electrode assembly is not used, the problem of capacity reduction of the battery cell can be solved. As described above, the present invention provides a high-capacity battery cell that can be applied to devices of various sizes and shapes in accordance with the rapid growth of portable electronic devices (portable devices) or wearable devices having various functions .

In the battery cell according to the present invention, the outer shape of the electrode assembly having a structure in which planar portions of different sizes are folded in a zigzag shape has a structure corresponding to the inner surface of the cylindrical battery cell, and the battery case made of metal can has durability Which is more suitable for protecting the electrode assembly, the battery case may be a cylindrical metal can.

In one specific example, the electrode assembly is housed in the battery case in a folded state in a zigzag fashion, and contact with the inner surface of the battery case may occur. Therefore, it is preferable that a separation membrane for preventing contact with the battery case is disposed at the outermost part of the electrode assembly. The electrode assembly further includes a second separation membrane located on the outer surface of the anode sheet and a third separation membrane located on the outer surface of the anode sheet Lt; / RTI >

The electrode mixture is coated on at least one surface of the positive electrode sheet and the negative electrode sheet and the electrode mixture is coated on one surface of the electrode sheet facing the first electrode sheet or when the electrode mixture is coated on the other surface of the electrode sheet facing the first separating sheet Or both electrode sides of the electrode sheet can be coated with an electrode mixture to increase the capacity of the electrode.

Meanwhile, in order to realize the zigzag shape of the electrode assembly, the positive electrode sheet and the negative electrode sheet are each formed with a bent portion. When the electrode sheet is bent, considering that the electrode mixture applied around the bent portion is highly likely to be removed , And the unfolded portion to which the electrode mixture is not applied is preferably formed on the bent portion.

In one specific example, the electrode assembly is built such that an anode tab attached to one end of the electrode sheet protrudes toward the top of the electrode case, and the anode tab and the cathode tab are perpendicular to the bottom surface of the battery case It is preferable that the size of the bar, the size of the anode flat portions and the size of the cathode flat portions are set to be smaller than the height of the battery case, and the overall shape of the electrode assembly is a cylindrical structure. .

On the other hand, when the electrode assembly is embedded in the battery case, it is necessary to consider the direction of the electrode assembly when the number of the anode flat portion and the cathode flat portion is an even number. In order to prevent such inconvenience, It is preferable that the number of flat portions is an odd number. Therefore, the total number of the anode plane portion and the cathode plane portion may be 2n-1 (n is a natural number of 3 or more).

Specifically, the positive electrode plate and the negative electrode sheet have the same number of planar portions located on both sides of the anodic plane portion and the negative electrode planar portion located at the center portion. In the bent state, the overall shape of the electrode assembly is cylindrical The anode sheet and the cathode sheet may have a structure in which the size of the n-th anode flat part and the n-th negative flat part located at the center with respect to the longitudinal direction is the largest and the size is decreased toward both ends .

At this time, the sizes of the anode flat portions and the cathode flat portions may be formed symmetrically with respect to the n-th anode flat portion or the n-th negative flat portion.

In one specific example, the bent portion where the positive electrode sheet and the negative electrode sheet are bent may be formed with a bending guide line for facilitating bending. The shape of the bending guide line is not particularly limited as long as the bending guide line can easily and concisely bend. For example, the bending guide line may be formed of a recessed groove or a plurality of slits.

In the electrode sheet included in the battery cell according to the present invention, an electrode tab protruding toward the upper part of the battery case is attached to the electrode case when the electrode tab is housed in the battery case. And can be attached by welding to an uncoated region where the electrode mixture is not applied.

Specifically, the electrode tabs may be formed in two or more numbers, and may be formed on the same outer periphery of the electrode sheet, or may be formed on different outer periphery.

For example, when there are two electrode tabs, the electrode tab may be formed on one end of the electrode sheet protruding toward the top of the battery case. Alternatively, when the number of the electrode tabs is three or more, the electrode tab may include one end of the electrode sheet protruding toward the top of the battery case, and may be formed on the left and / or right outer peripheries connected to the one end.

In one specific example, when the separator is not formed on the outer surface of the positive electrode sheet of the electrode assembly and the outer surface of the negative electrode sheet, contact between the electrode assembly and the battery case and electrical short-circuit may occur, The electrode assembly may have a structure in which the separating film surrounds the outer circumferential surface of the electrode assembly so as to be perpendicular to the longitudinal direction of the electrode sheet or a separation film is interposed between the inner surface of the battery case and the outer surface of the electrode assembly. have.

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

Specifically, the battery pack may be used as a power source for devices requiring high-temperature safety, long cycle characteristics, and high rate characteristics. Examples of such devices include a mobile electronic device, a power A power tool; An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and the like; An electric motorcycle including an electric bike (E-bike) and an electric scooter (E-scooter); An electric golf cart; And a power storage system, but the present invention is not limited thereto.

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 cell according to the present invention has a structure in which a zigzag-shaped electrode assembly is housed in a cylindrical battery case. Since the overall shape of the electrode assembly corresponds to the inside of the battery case, It is possible to provide a secondary battery with a high capacity. In addition, when a battery case made of metal can is used, the battery cell can be improved in durability, so that explosion or ignition due to an impact applied from the outside can be prevented, thereby providing a secondary battery improved in safety.

1 is a perspective view showing an electrode assembly housed in a battery case;
2 is a schematic plan view of an electrode current collector according to one embodiment;
3 is an exploded perspective view showing the structure of an electrode assembly according to one embodiment;
4 is a partial enlarged view of a bending guide line according to one embodiment;
5 is a perspective view of an end of an electrode sheet to which an electrode tab is attached; And
6 is a perspective view showing a separation film disposed between the battery case and the electrode assembly.

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.

FIG. 1 is a perspective view of a battery case incorporating an electrode assembly of the present invention, and FIG. 2 is a schematic plan view of an electrode assembly according to an embodiment of the present invention.

Referring to FIGS. 1 and 2, the electrode assembly 120 is folded in a zigzag shape and is embedded in the battery case 110 in a bent state in the direction of the arrow. The battery assembly 110 may be a cylindrical battery case in order to reduce a space between the electrode assembly and the battery case, since the overall shape of the electrode assembly 120 in a bent state is a cylindrical shape. In order to stably store the electrode assembly 120 in the battery case 110, the width W of the largest central plane portion 125 among the flat portions of the electrode assembly is equal to the height W 'of the battery case And the height 121 of the center plane portion 125 is formed to be smaller than the diameter of the top surface 115 of the battery case.

Specifically, the electrode current collector 200 includes seven planar portions 210, 220, 230, 240, and 250 from the first planar portion 210 to the seventh planar portion 270 arranged in the longitudinal direction L of the electrode sheet , 260 and 270, and the widths W1 of the flat portions are all formed to be the same. However, since the height of the flat portion is different from that of the fourth flat portion 240, the height H _{4 of} the fourth flat portion 240 positioned at the center is the largest, The heights H ₃ and H ₅ of the first and second flat portions 230 and 250 are formed at the same height within a range smaller than the height H ₄ of the fourth flat portion. Therefore, the height of the planar portions positioned on both sides of the fourth planar portion is symmetrical.

However, the number of the planar portions constituting the electrode current collector 200 is not limited to seven, and may be set in consideration of the size of the battery case and the capacity of the battery. In addition, The number of the planar portions may be 2n-1 (n is a natural number of 3 or more).

3 is an exploded perspective view schematically illustrating an electrode assembly according to an embodiment of the present invention.

3, the electrode assembly 300 includes a cathode sheet 310, a first separator 331, and a second separator 332 having a structure in which separators are disposed adjacent to the anode sheet 310 and the cathode sheet 320, The second separator 332 may be disposed on the outer surface of the anode sheet 310 and the third separator 333 may be further disposed on the outer surface of the anode sheet 320. [ . ≪ / RTI >

The positive electrode mixture 311 and the negative electrode mixture 321 are applied to at least one surface of the positive electrode sheet 310 and the negative electrode sheet 320. The bending portions 312 and 322 between the respective planar portions are provided with electrodes Uncoated portions 313 and 323 to which the electrode material mixture is not applied are formed to prevent the mixture from being desorbed.

The separators 331, 332, and 333 may be formed as outer peripheries formed by dotted lines, but they are preferably formed of solid outer peripheries having a shape corresponding to the shape of the electrode current collector for easy storage in the battery case .

Fig. 4 schematically shows the bent portion between the flat portions of the electrode sheet.

4, a folded portion 421 is formed between the n-th plane portion 411 and the (n + 1) -th flat portion 412 of the electrode sheet 400, For example, the bending guide line 422 may be formed of a recessed groove or a plurality of slits. The bending guide line 422 may be formed on the bending guide line 421 to facilitate bending.

Fig. 5 schematically shows a perspective view of an electrode sheet to which electrode tabs are attached.

5, electrode tabs 511 and 512 are attached to one end 510 of the electrode sheet 500 facing upward when stored in the battery case, and the opposite end 570 of the electrode sheet 500 is connected to the electrode tabs 511 and 512, The electrode tabs are not attached. Although two electrode tabs 511 and 512 are illustrated, the electrode tabs 511 and 512 may be formed of one or more than two electrode tabs 511 and 512 and may be formed on the same outer periphery 521 of the electrode sheet, (521, 522, 523), respectively.

6 schematically shows a state in which an electrode assembly according to an embodiment is embedded in a battery case.

Referring to FIG. 6, the electrode assembly 610 is an electrode assembly that does not include the second separator or the third separator, and the electrode collector coated with the electrode mixture on the outer surface of the electrode assembly is exposed. The electrode assembly 610 having such a structure is likely to explode or ignite due to a short circuit due to contact with the battery case 630. The outer circumferential surface of the electrode assembly 610 is perpendicular to the longitudinal direction L of the electrode sheet The separation film 620 surrounds the separation film 620. [

Alternatively, the separation film 620 may be formed on the inner surface of the battery case 630 so that the separation film 620 is interposed between the outer surface of the electrode assembly 610 and the battery case 630.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (18)

A battery cell in which an electrode assembly having a structure bent in a zigzag shape is embedded in a battery case,
Wherein the electrode assembly comprises a positive electrode sheet and a negative electrode sheet, and a first separator interposed between the positive electrode sheet and the negative electrode sheet,
The positive electrode sheet and the negative electrode sheet are arranged such that the nth anodic plane portion confronts the (n + 1) th anodic flat portion (n is a natural number of 2 or more) while the electrode tab is formed at the same end portion, Is bent in a zigzag shape along the longitudinal direction (L) of the sheet so as to face the negative electrode plane portion (n is a natural number of 2 or more)
Wherein n anode plane portion size (H _n) and the n + 1 positive flat portion, the size of (H _{n + 1)} different from one another, wherein the n cathode planar portion size (H _{n ')} and the n + 1 negative plane (H _{n + 1 '} ) are different from each other,
Wherein the electrode tab is protruded toward an upper portion of the battery case, and the anode flat portion and the cathode flat portion are built in such a manner as to be perpendicular to a lower end surface of the battery case. The battery cell according to claim 1, wherein the battery case is a cylindrical metal can. The battery cell of claim 1, wherein the electrode assembly further comprises a second separator located on an outer surface of the anode sheet, and a third separator located on an outer surface of the anode sheet. The battery cell according to claim 1, wherein at least one surface of each of the positive electrode sheet and the negative electrode sheet is coated with an electrode mixture. The battery cell according to claim 1, wherein the bipolar portions of each of the positive electrode sheet and the negative electrode sheet for implementing the zigzag shape are formed with uncoated portions that are not coated with the electrode mixture. The battery cell according to claim 1, wherein the sizes of the anode flat portions and the cathode flat portions are constant in a range smaller than the height of the battery case. The battery cell according to claim 1, wherein the total number of the anode flat portion and the cathode flat portion is 2n-1 (n is a natural number of 3 or more). The battery according to claim 1, wherein the positive electrode sheet and the negative electrode sheet have a largest n-th anodic plane portion and a n-th negative flat portion located at the center with respect to the longitudinal direction, Cell. The battery cell according to claim 8, wherein the sizes of the anode flat portions and the cathode flat portions are symmetrical with respect to the n-th anode flat portion or the n-th flat portion. The battery cell according to claim 1, wherein a bent guide line is formed on the bent portion of the positive electrode sheet and the negative electrode sheet to facilitate bending. The battery cell according to claim 10, wherein the bending guide line comprises a recessed groove or a plurality of slits. The battery cell according to claim 1, wherein one or more electrode tabs are formed per electrode. The battery cell according to claim 12, wherein the electrode tabs are formed in a number of two or more and are formed on the same outer periphery of one side of the electrode sheet or on different outer peripheries. The battery cell according to claim 1, wherein the separating film surrounds the outer circumferential surface of the electrode assembly so as to be perpendicular to the longitudinal direction of the electrode sheet. The battery cell according to claim 1, wherein a separation film is interposed between an inner surface of the battery case and an outer surface of the electrode assembly. A battery pack comprising the battery cell according to any one of claims 1 to 15 as a unit cell. A device as claimed in claim 16 comprising a battery pack as a power source. 18. The apparatus of claim 17, wherein the device comprises: a mobile electronic device; a power tool powered by a battery-based motor; An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and the like; An electric motorcycle including an electric bike (E-bike) and an electric scooter (E-scooter); An electric golf cart; Wherein the system is a system for power storage.

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