KR101125592B1 - High Capacity Battery Cell of High Life Characteristics and Safety - Google Patents

Abstract

The present invention is prepared by winding a small electrode assembly ('bicell') having a stack-type structure composed of the same electrode on both sides or a small electrode assembly ('full cell') having a stack-type structure composed of electrodes having both sides with a long separator sheet. A secondary battery including a stack-foldable structure cell ('unit cell'), wherein two or more of the unit cells are housed in one battery case, and one or more unit cells are disposed at both ends. Electrode terminals protrude, and the unit cells are mounted in one accommodating part while forming a stacked arrangement structure with the electrode terminals connected to each other, and a sheet ('heat-dissipating sheet') having excellent thermal conductivity is interposed between the unit cells. It provides a secondary battery consisting of a structure.

Therefore, the high capacity secondary battery according to the present invention can improve the structural stability by increasing the electrical and physical coupling force between the unit cells, can greatly increase the capacity by a simple assembly process, interposed between the thermally conductive member between the unit cells By doing so, there is an effect of shortening the lifespan due to deterioration of battery components and safety problems due to high heat generation.

Description

High Capacity Battery Cell of High Life Characteristics and Safety

1 is a perspective view showing a stack-type parallel connection structure of unit cells forming a secondary battery according to an embodiment of the present invention;

FIG. 2 is a perspective view showing a stacked arrangement of parallel connection units of unit cells in which a pair of positive and negative terminals protrude from both sides as a modification of FIG. 1;

3 is a partial cross-sectional view of the unit cells forming the secondary battery of FIG. 1;

4 is a perspective view illustrating a series connection structure of unit cells forming a secondary battery according to still another embodiment of the present invention;

5 is an exploded perspective view of a rechargeable battery including the unit cells of FIG. 4.

The present invention relates to a high capacity battery cell including two or more unit cells, and more particularly, a small electrode assembly having a stacked structure in which both sides are made of the same electrode, or a small structure in which the stacked structure is made of different electrodes in both sides. A secondary battery including a cell having a stack-folding structure ('unit cell') manufactured by winding an electrode assembly with a long separator sheet, wherein two or more of the unit cells are housed in one battery case. One or more electrode terminals protrude from both ends of the unit cells, and the unit cells are mounted in one receiving unit while forming a stacked arrangement structure with the electrode terminals connected thereto. Secondary battery made of a structure interposed with excellent sheet, and a battery cell including such secondary batteries Relate to.

With the development of technology and increasing demand for mobile devices, the demand for secondary batteries is also rapidly increasing. Among them, lithium secondary batteries with high energy density, high operating voltage, and excellent storage and life characteristics are used for various mobile devices as well as various electronic products. It is widely used as an energy source.

Secondary batteries are classified into roughly cylindrical cells, square cells, and pouch cells according to external and internal structural features. Among them, rectangular batteries and pouch cells having a small width to length are particularly noticeable. I am getting it.

The electrode assembly of the anode / separation membrane / cathode structure constituting the secondary battery is largely divided into a jelly-roll type (wound type) and a stack type (lamination type) according to its structure. The jelly-roll type electrode assembly is coated with an electrode active material or the like on a metal foil used as a current collector, dried and pressed, cut into bands of a desired width and length, and the membrane is separated using a separator to form a spiral. It is manufactured by winding. The jelly-roll type electrode assembly is suitable for cylindrical batteries, but has disadvantages such as peeling of electrode active materials and low space utilization when applied to square or pouch type batteries. On the other hand, the stacked electrode assembly has a structure in which a plurality of anode and cathode unit cells are sequentially stacked, and has an advantage of easily obtaining a rectangular shape, but when the manufacturing process is complicated and an impact is applied, the electrode is pushed and a short circuit occurs. There is a disadvantage that is caused.

In order to solve this problem, the electrode assembly of the advanced structure of the jelly-roll type and the stacked form, a full cell or anode (cathode) / separator / cathode of a certain unit size of the anode / separator / cathode structure A stack-foldable electrode assembly was developed in which a bicell of (anode) / membrane / anode (cathode) structure was folded using a continuous separation film of a long length, which was disclosed by the applicant of Korean patent application. No. 2001-82058, 2001-82059, 2001-82060, and the like.

In general, in order to increase capacity in a stack-foldable electrode assembly, the number of full cells or bicells constituting is increased. However, as the number of full cells or bicells increases, the space for the folding process increases and a large amount of work time is required, and when a failure occurs in some cells, the entire electrode assembly may be defective.

On the other hand, as the number of windings and / or stackings increases to increase the capacity of the battery, the heat dissipation problem is seriously raised. Since the lithium secondary battery generates heat during charging and discharging, when such heat is not effectively removed and accumulated, the lithium secondary battery may cause deterioration of the battery and greatly deteriorate safety. In particular, a battery that requires high-speed charging and discharging characteristics, such as a power source of an electric vehicle, a hybrid electric vehicle, or the like, has a strong heat generation in the process of providing a high power instantaneously.

This heat dissipation problem inevitably occurs in a structure in which the electrode plates are packed with high density for high capacity of the battery, and in particular, the heat generation problem at the central portion that is the longest distance from the outer surface of the electrode assembly is serious.

Therefore, there is a high need for a technology that can improve the lifespan and safety of the secondary battery by increasing the capacity of the battery in an easy manner and by constructing a structure that is easy to discharge a lot of heat generated during high-speed charging and discharging to the outside. to be.

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

Specifically, the first object of the present invention is to provide a technology capable of manufacturing a large capacity secondary battery by a simple assembly process. Such a secondary battery may be preferably used as a unit cell of a medium-large battery module, such as an electric vehicle, a hybrid electric vehicle, and the like.

A second object of the present invention is to provide a technology for improving the lifespan and safety of a secondary battery by solving the heat accumulation problem caused by the large capacity of the battery.

A secondary battery according to the present invention for achieving the above object is a small electrode assembly ('bicell') of the stack-like structure consisting of the same electrode on both sides or a small electrode assembly ('full cell) of the stack-type structure consisting of different electrodes on both sides A secondary battery including a stack-foldable structure ('unit cell') manufactured by winding ') into a long separator sheet, wherein two or more of the unit cells are embedded in one battery case, and One or more electrode terminals protrude from both ends of the unit cells, and the unit cells are mounted in one receiving unit while forming a stacked arrangement structure with the electrode terminals connected thereto. It has a structure in which an excellent sheet ('heat radiation sheet') is interposed.

Accordingly, the secondary battery according to the present invention has increased battery capacity by including two or more unit cells in one battery case, and electrical and mechanical by electrode terminals protruding from the both ends thereof. By connecting to it has the advantage that the structural stability of the external environment, such as shock or vibration is improved. In addition, since two or more unit cells are stably coupled as one unit, there is an advantage in that handling is easy in the assembling process of the secondary battery.

In addition, since the secondary battery has a heat dissipation sheet having excellent thermal conductivity between two or more unit cells, the heat dissipation sheet absorbs heat in the center of many unit cells generated during high-speed charging and discharging, so that the heat dissipation sheet absorbs heat toward the outer peripheral surface of the unit cells. By inducing the divergence, it is possible to shorten the life of the battery due to deterioration of the elements constituting the battery or to prevent the battery from firing due to high heat generation.

First, looking at some prior art with respect to the first feature of the present invention, although the electrode assembly is not made of a stack-folding structure, Korean Patent Application Publication Nos. 2004-0054201 and 2004-0092533 In order to increase the capacity of the pouch-type battery case or a rectangular battery case, a technique for connecting two or more stacked electrode assembly or wound electrode assembly in a parallel manner is mounted. However, the above techniques have a disadvantage in that structural stability is very low because two or more electrode assemblies are coupled only at the electrode terminals for electrical connection, and such electrode terminals protrude only at one end of the electrode assembly. Such a problem may act as one of the main causes of deterioration of safety when exposed to an external environment such as shock or vibration that may occur frequently in a secondary battery requiring high capacity.

Looking at some prior art in relation to the second aspect of the present invention, Japanese Patent Application Publication Nos. 1993-159808, 1997-115552, 2003-297303, 2005-056655, etc. Disclosed is a technique of preventing an internal short circuit from affecting an electrode which has entered, or interposing a heat dissipation member between electrodes in order to dissipate heat, or inserting a heat dissipation member between separators. These techniques are commonly characterized by interposing said heat dissipation related member between electrode plates in a jelly-roll type, stacked electrode assembly. However, the preparation of the electrode assembly with the addition of the heat dissipation member in the jelly-roll type or the stacked electrode assembly makes the assembly process very complicated, resulting in a problem that the battery capacity reduction due to the member is inevitable.

On the other hand, the secondary battery of the present invention solves the above problems simultaneously by its characteristic structure.

In the present invention, the unit cells are composed of a predetermined number of full cells or bicells as described above.

The full cell is a cell in which an anode and a cathode are positioned at both sides, respectively, and means a unit cell having a structure of an anode, a separator, and a cathode. For example, the full cell may include an anode / separator / cathode cell and an anode / separator / cathode / cathode / anode / separator / cathode cell having the most basic structure. In order to configure the unit cell using such a full cell, a plurality of full cells should be stacked such that the positive electrode and the negative electrode face each other with the separation film interposed therebetween.

In addition, the bi-cell is a structure in which the same electrode is located on both sides, that is, a cell of a cathode-anode or a cathode-cathode structure, for example, the bicell is an anode / separator / cathode / separator / anode cell and A cathode / separator / anode / separator / anode cell, etc. are mentioned. In order to configure the unit cell using such a bicell, a bicell (anode bicell) and a cathode / separator / anode / separator / cathode structure having an anode / separator / cathode / separator / anode structure with a separator film interposed therebetween. The plurality of bicells should be stacked so that the bicells (cathode bicells) face each other.

In the present invention, a bicell can be preferably used as the unit cell constituting the unit cell. In consideration of a battery assembly process, operating performance, and the like, a preferable number of the bicells is 3 to 30 pieces.

The unit cells, to which the electrode terminals are connected, have a stacked arrangement structure as described above. Here, the “stacked arrangement structure” means a structure in which the unit cells are arranged to be adjacent in the thickness direction thereof.

The heat dissipation sheet interposed between the unit cells is not particularly limited as long as the heat dissipation sheet is a member having high thermal conductivity, and may be formed of, for example, a carbon sheet. Since the carbon sheet has conductivity, the carbon sheet should be interposed between the unit cells in a state where electrical insulation from the unit cells is ensured. For example, the carbon sheet and the unit cells may be formed by applying a separator to an outer surface of the unit cell in contact with the carbon sheet. It may be a structure to electrically insulate.

In one preferred embodiment, the heat dissipation sheet is configured to be the same or smaller than the size of the electrode plate constituting the unit cell, it can prevent the short circuit with the electrode terminal of the unit cell, the thickness of the heat dissipation efficiency and the In consideration of the capacity, it is preferably formed in a range of 0.1 to 1 mm.

In the secondary battery according to the present invention, a structure in which a plurality of unit cells are connected in a parallel manner and a structure connected in a series manner are both possible.

In one preferred example, the unit cells are each formed with one electrode terminal at both ends thereof, and the unit cells are stacked in the thickness direction thereof so that the electrode terminals of the same pole face the same direction, and the unit cell It may be a structure for coupling the electrode terminals of the same pole in parallel at both ends of the.

In a specific example, when two unit cells (first unit cell and second unit cell) are connected to form an electrode assembly, the unit cells have one anode terminal formed at one end thereof and a cathode at the other end thereof. As a structure in which terminals are formed, for example, the first unit cell is arranged such that its positive terminal faces the lower end of the unit cell (based on the direction of the completed battery cell), and the second unit cell is arranged in the first unit cell. In a state of being stacked on the bottom of the unit cell, its positive terminal is also arranged to face the bottom. Accordingly, the first unit cell is stacked on the second unit cell, and the positive terminal of the first unit cell, the positive terminal of the second unit cell, and the negative terminal of the first unit cell and the first unit cell are formed at both ends. The cathode terminals of the two unit cells are coupled to each other to form a stacked arrangement structure in which two unit cells are connected in parallel.

In some cases, each of the unit cells may have two electrode terminals formed at both ends thereof, and electrode terminals formed at one end of the unit cells may have the same pole or different pole structures. That is, the unit cell has a pair of positive and negative terminals formed at one end thereof, so that a total of four electrode terminals protrude in two pairs. In such a structure, unit cells may be stacked in the thickness direction such that electrode terminals of the same pole are adjacent to each other, and electrode terminals of the same pole may be coupled in parallel to each other at both ends of the unit cells.

In the above-described battery cells, a plurality of unit cells are connected in parallel, but in some cases, they may be connected in series. Since the battery cells in which the unit cells are connected in series are charged and discharged at a relatively high voltage, battery cell components such as electrode active materials and electrolytes must be configured to be safe under such high voltage conditions.

As an example of a series connection, unit cells each have one electrode terminal formed at both ends thereof, and these unit cells are arranged in the length direction thereof so that electrode terminals of the same pole face the same direction, and two adjacent cells are arranged. After the electrode terminals of different poles are coupled in series at opposite ends of the unit cells, the electrode terminal connecting portions may be bent to form a stacked arrangement structure.

As a specific example, when connecting two unit cells (third unit cell, fourth unit cell), the unit cells have a structure in which positive and negative terminals are formed at both ends thereof, for example, The three unit cell is arranged such that its positive terminal faces the top direction of the unit cell, and the fourth unit cell is also arranged so that its positive terminal faces adjacent to the negative terminal located at the bottom of the third unit cell while facing the top direction. Accordingly, the lower end of the third unit cell and the upper end of the fourth unit cell face each other, thereby mutually coupling the negative terminal of the third unit cell and the positive terminal of the fourth unit cell formed at each end to each other. Can be connected in series. In addition, the electrode terminal connecting portion may be bent to have a stacked arrangement structure.

In this structure, the electrode terminals which are not coupled to each other among the electrode terminals of the unit cell may be spaced apart from the left side of the unit cell so as to be spaced apart at predetermined intervals, for example, from one side of the battery case. It may be a structure that is biased to the right.

In some cases, one of the unit cells may be heat-sealed in a state in which a separator sheet thereof is elongated and all the unit cells are wrapped with an excess of the separator sheet. Due to this structure, it is possible to improve the structural stability by further increasing the coupling force between the unit cells.

Secondary battery according to the present invention can be preferably used in the manufacture of large-capacity medium-large battery module or battery pack, the range of the large capacity is not particularly limited.

Accordingly, the present invention provides a medium-large battery pack including a medium-large battery module including a plurality of secondary batteries as a unit cell, and at least one such medium-large battery module and a control unit for controlling the operation of the battery module. .

Since the structure and manufacturing method of such a medium-large battery module and a battery pack are known in the art, description thereof will be omitted.

The medium-large battery pack of the present invention requires a high power and a large amount of electricity, such as an electric vehicle, a hybrid electric vehicle, an electric motorcycle, an electric bicycle, and is particularly preferable as a power source of a device to which a lot of external forces such as vibration and shock are applied.

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 schematically illustrating a stack-type parallel connection structure of unit cells forming a secondary battery according to an embodiment of the present invention.

Referring to FIG. 1, unit cells (first unit cell and second unit cell: 100 and 200) have a structure in which a plurality of bicells having a stacked structure in which both sides are formed of the same electrode are folded by a separate separator sheet. consist of. The structure of these bi-cells can be more easily confirmed in FIG.

Referring to FIG. 3, the first unit cell 100 includes bicells 150 and 152 having an anode / separator / cathode / separator / anode structure and a bicell 151 having a cathode / separator / anode / separator / cathode structure. The long separator sheet 160 is alternately folded. Here, the long separator sheet 160 extends long enough to fold the bicells 150, 151, and 152 constituting the first unit cell 100, and the surplus portion of the separator sheet 160 may be formed. The heat dissipation sheet 160 having a smaller size than the pole plates constituting the unit cells 100 and 200 is inserted between the first unit cell 100 and the second unit cell 200. have.

Referring back to FIG. 1, the first unit cell 100 and the second unit cell 200 are composed of a plurality of bicells, each having one negative electrode terminal 110 and 210 and a positive electrode terminal 120 at both ends thereof. , 220 is formed to protrude, and the cathode terminals 110 and 210 are arranged to face the upper end of the unit cell, respectively. Accordingly, the first unit cell 100 is stacked on top of the second unit cell 200, and the cathode terminals 110 and 210 and the anode terminals 120 and 220 are respectively welded at both ends. In combination, the two unit cells 100 and 200 may be stacked in a stacked arrangement structure.

The heat dissipation sheet 160 having excellent thermal conductivity between the first unit cell 100 and the second unit cell 200 absorbs heat existing in the centers of the unit cells 100 and 200 to absorb the unit cells 100,. It performs a function to generate heat in the direction of the outer circumferential surface (200). Therefore, it is possible to suppress thermal accumulation due to the stacking of the unit cells 100 and 200, thereby suppressing deterioration of the battery and improving safety.

2 schematically shows a perspective view of the modification of FIG. 1.

Although FIG. 2 is a stacked arrangement parallel connection structure, there is a difference from the structure of FIG. 1 in that unit cells having a pair of positive and negative terminals protruding from each side are used. Referring to FIG. 2, the third unit cell 500 and the fourth unit cell 600 each have a pair of electrode terminals protruding from both ends thereof, and the third unit cell 500 and the fourth unit cell ( The heat dissipation sheet 160 is inserted between 600. The electrode terminals 510 and 520 formed together on the upper end of the third unit cell 500 may be the same electrode or different electrodes. When the upper electrode terminals 510 and 520 of the third unit cell 500 are the same cathode, the upper electrode terminals 610 and 620 of the fourth unit cell 600 are also the same cathode, and their coupling relationship is Same as in FIG. 1. As a result, cathodes are formed at the upper end of the battery cell by the upper electrode terminals 510, 520, 610, and 620 of the third unit cell 500 and the fourth unit cell 600, and the lower end of the battery cell is formed at the lower end of the battery cell. An anode is formed by the lower electrode terminals 511, 521, 611, and 621 of the third unit cell 500 and the fourth unit cell 600.

As another example, the electrode terminals 510 and 520 formed together on the upper end of the third unit cell 500 may be different electrodes as cathodes and anodes, respectively. In this case, the upper electrode terminals 610 and 620 of the fourth unit cell 600 may also be configured to correspond to the cathode and the anode, and may be connected to each of the same electrodes to form a parallel connection structure. Lower electrode terminals 511, 521, 611, and 621 of the third unit cell 500 and the fourth unit cell 600 also have the same electrode structure and connection method as described above. As a result, a battery cell is formed in which the third unit cell 500 and the fourth unit cell 600 form a parallel connection structure in a stacked arrangement, and have positive and negative terminals respectively formed on top and bottom thereof. As devices of various structures emerge, it is expected that battery cells of the above modified structure may also be used, depending on their unique form.

4 is a perspective view schematically showing a series connection structure of unit cells forming a secondary battery according to another embodiment of the present invention.

Referring to FIG. 4, the fifth unit cell 700 is arranged such that its negative terminal 710 faces upward, and the sixth unit cell 800 also arranges its negative terminal 810 facing upward. At the same time, by being located at the bottom of the fifth unit cell 700, it is adjacent to the positive terminal 720 of the fifth unit cell 700. Therefore, the anode terminal 720 of the fifth unit cell 700 and the cathode terminal 810 of the sixth unit cell 800 are joined by welding to connect the two unit cells 700 and 800 in series. .

After the two unit cells 700 and 800 form a stacked arrangement structure by bending the connection portions of the electrode terminals 720 and 810, as shown in FIG. 5, the two unit cells 700 and 800 are built in the accommodating part 910 of the battery case 900. The battery 1000 can be manufactured. This structure can be more easily confirmed in FIG.

Referring to FIG. 5, the secondary battery 1000 has respective electrode terminals 720 protruding from one end thereof in a state in which a heat shield sheet 160 is interposed between two unit cells 700 and 800. The 810 is coupled to each other, mounted on the housing 910 of the battery case 900, and then sealed by a cover.

With the two unit cells 700 and 800 mounted inside the battery case 900, the uncoupled electrode terminals 710 and 820 of the unit cells 700 and 800 may be spaced apart from each other to protrude. The unit cells 700 and 800 are formed to have a structure biased toward one side. For convenience of understanding, in FIG. 5, the negative electrode terminal 710 of the fifth unit cell 700 and the positive electrode terminal 820 of the sixth unit cell 800 are expressed as having a height deviation, but the actual manufacture of the battery In the process they may be mounted to be located together at the front end of the battery case (900). An electrode lead (not shown) may be used in the mounting process in such a parallel position.

The method of configuring the secondary battery according to the present invention using the two unit cells 100, 200; 500, 600 of the parallel connection structure according to FIGS. 1 and 2 is substantially the same as that of FIG. There is a difference in that the negative terminal and the positive terminal as input / output terminals protrude to the top and bottom of the battery case 900, respectively.

Although described above with reference to the drawings according to an embodiment of the present invention, those of ordinary skill in the art will be able to perform various applications and modifications within the scope of the present invention based on the above contents.

As described above, the high capacity secondary battery according to the present invention can improve the structural stability by increasing the electrical and physical coupling force between the unit cells, can greatly increase the battery capacity by a simple assembly process, between the unit cells By interposing the thermally conductive member, there is an effect of shortening the lifespan due to deterioration of battery components and safety problems due to high heat generation.

Claims (16)

A stack manufactured by winding a small electrode assembly ('bicell') having a stacked structure on both sides of the same electrode or a small electrode assembly ('full cell') having a stack structure consisting of electrodes on both sides with a long separator sheet- A secondary battery including a folding type cell ('unit cell'), wherein two or more of the unit cells are housed in one battery case, and the unit cells have one or more electrode terminals at both ends thereof. The unit cells are protruded and mounted in one housing while forming a stacked structure in which electrode terminals are connected, and a sheet ('heat-dissipating sheet') having excellent thermal conductivity is interposed between the unit cells. Secondary battery consisting of. The secondary battery of claim 1, wherein the unit cell includes 3 to 30 bicells. delete The secondary battery of claim 1, wherein the heat dissipation sheet is smaller than or equal to the size of the electrode plate constituting the unit cell. The secondary battery of claim 1, wherein the heat dissipation sheet has a thickness of 0.1 to 1 mm. The secondary battery of claim 1, wherein the heat dissipation sheet is a carbon sheet. The secondary battery of claim 1, wherein the plurality of unit cells have a structure connected in a parallel manner or a structure connected in a series manner. The method of claim 7, wherein the unit cells are formed with one electrode terminal at both ends, each of the unit cells in the thickness direction so that the electrode terminals of the same pole facing the same direction, the same at both ends of the unit cells Secondary battery characterized in that the electrode terminals of the poles are connected in a parallel manner. 8. The unit cells of claim 7, wherein two electrode terminals are formed at both ends, and electrode terminals at each end are formed of the same pole, and the unit cells are stacked in the thickness direction such that electrode terminals of the same pole are adjacent to each other. And connecting electrode terminals of the same pole at both ends of the unit cells and connected in parallel. 8. The unit cells of claim 7, wherein two electrode terminals are formed at both ends of the unit cells, and electrode terminals at each end are formed of different poles, and the unit cells are disposed in the thickness direction such that the electrode terminals of the same pole are adjacent to each other. A secondary battery, comprising: stacking and connecting electrode terminals of the same pole at both ends of unit cells and connected in parallel. 8. The unit cells according to claim 7, wherein each of the unit cells has one electrode terminal formed at both ends thereof, and the unit cells are stacked such that electrode terminals of the same pole face in opposite directions to each other, and at each of the end portions facing each other. Secondary battery, characterized in that to connect the electrode terminals of the other pole connected in series. The method of claim 11, wherein the electrode terminals of the electrode terminals of the unit cells that are not coupled to each other are biased toward the left and right of each of the unit cells, so that when the battery terminal is mounted in the battery case, it can be spaced apart from one side of the battery case Secondary battery characterized in that. The secondary battery according to claim 1, wherein one of the unit cells (a) of the unit cells is heat-sealed in a state in which a separator sheet thereof is elongated and all the unit cells are wrapped with an excess of the separator sheet. . The secondary battery of claim 1, wherein the battery is a large capacity battery. A medium to large battery module including a plurality of secondary batteries according to any one of claims 1, 2 and 4 to 14 as a unit cell. A medium to large battery pack comprising one or more medium and large battery modules according to claim 15 and a control unit for controlling the operation of the battery module.

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