KR101498471B1 - Secondary Battery Empolyed with Battery Case Having Groove - Google Patents

Abstract

The present invention provides a battery case in which an electrode assembly having a positive electrode, a negative electrode, and a separator interposed between an anode and a cathode is embedded in a battery case of a laminate sheet, a cathode terminal and an anode terminal protruding from one end of the battery case, A linear groove ruptured when the electrode assembly moves toward the electrode terminal and / or when a high voltage is generated in the battery when the external impact is applied to the outer surface of the battery case is formed parallel to the cathode terminal and the cathode terminal And a secondary battery.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a secondary battery including a battery case having a groove formed therein,

The present invention relates to a secondary battery including a battery case having a groove formed therein, and more particularly, to a secondary battery including a positive electrode, a negative electrode, and an electrode assembly having a separator interposed between the positive and negative electrodes, The positive electrode terminal and the negative electrode terminal protrude from one end of the battery case, and when an external impact is applied to the outer surface of the battery case, when the electrode assembly moves toward the electrode terminal and / And a linear groove to be ruptured is formed parallel to the positive electrode terminal and the negative electrode terminal.

As technology development and demand for mobile devices have increased, there has been a rapid increase in the demand for secondary batteries as energy sources. Among such secondary batteries, much research has been conducted on lithium secondary batteries with high energy density and discharge voltage, .

BACKGROUND ART [0002] Generally, a secondary battery is a pouch-type battery in which an electrode assembly is embedded in a pouch-shaped case of an aluminum laminate sheet, .

The electrode assembly is embedded in a battery case. The electrode assembly includes a positive electrode / separator / negative electrode laminate structure. The positive electrode / separator / negative electrode has a jelly-roll type structure in which a separator is interposed between a positive electrode and a negative electrode coated with an active material. A plurality of positive electrodes and a plurality of negative electrodes of a predetermined size are stacked in a stacked state in a state in which a separator is interposed therebetween.

Such a secondary battery may be exposed to various environments depending on usage conditions and conditions, and it is required to prevent the risk of explosion especially for the safety of the user. Generally, the high temperature and high pressure inside the battery, which can be caused by an abnormal operating condition of the battery such as an internal short, an allowable current, a charging state exceeding a voltage, exposure to a high temperature, .

Therefore, in order to fundamentally solve such a problem, the present invention proposes a structure in which a battery case portion corresponding to an upper boundary surface of the electrode assembly is deformed into a predetermined shape.

In this connection, some techniques for forming a groove on one side of the battery case are known. For example, Japanese Patent Registration No. 3730981 discloses a structure in which a plurality of convex portions are provided on at least one surface of a battery case surrounding an electrode assembly for the purpose of improving heat dissipation, and the interior of the convex portions is filled with a filler. The above technique can improve the heat radiating property by increasing the film surface area of the battery case by a plurality of convex portions and filling the filler into the convex portion to stably maintain the shape. However, when the external force acts in the electrode tab direction It has been confirmed that it does not prevent internal short circuit due to upward movement of the electrode assembly.

Japanese Patent Application Laid-Open No. 2001-057179 discloses a battery case in which the bottom of the groove or the convex portion is formed on at least one surface of the battery case for suppressing expansion of the battery case to prevent deformation of the battery case, Discloses a structure of a secondary battery which forms a pattern. That is, as described in the specification, the above-described technique shows a structure in which mutually intersecting linear patterns exert a structural girder effect to increase the overall strength of the battery case, thereby preventing deformation due to expansion of the battery case . However, the above-described technique has a problem in that a predetermined effect can be obtained only when the line pattern has an intersecting structure such as an X-shape, and the battery case can be practically applied only to a metal can, Lt; / RTI > In addition, although the linear pattern must be formed to a considerable depth in order to exhibit a structural girder effect, such a process is highly likely to significantly impair the mechanical strength of the battery case, especially at the intersection of the linear pattern.

Accordingly, there is no difficulty in the actual manufacturing process, the short circuit due to the movement of the electrode assembly is prevented, and the internal gas of the battery cell is effectively discharged to prevent ignition or explosion of the battery cell beforehand, There is a high need for a technique capable of ensuring the quality of the product.

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.

More specifically, it is an object of the present invention to provide a battery case in which a linear groove formed in parallel to a cathode terminal and an anode terminal is formed on an outer surface of a battery case when an external impact is applied, And the electrode assembly and the electrode assembly are brought into contact with each other by the physical impact of the electrode tab or the electrode tab, and the risk of ignition or explosion of the battery is prevented through discharge of the high- Thereby providing a battery.

According to an aspect of the present invention, there is provided a rechargeable battery including an electrode assembly having a positive electrode, a negative electrode, and a separator interposed between an anode and a cathode, the electrode assembly being embedded in a battery case of the laminate sheet, A cathode terminal and a cathode terminal are protruded on the outer surface of the battery case, and the outer surface of the battery case is provided with a linear groove, which ruptures when the electrode assembly moves toward the electrode terminal and / Is formed parallel to the positive electrode terminal and the negative electrode terminal.

An internal short circuit caused by dropping of the battery, external impact or the like can act as a main cause of the explosion or ignition of the battery because the anode and the cathode come into contact with each other when the electrode assembly moves when the drop or impact is applied, Because of the high resistance heat caused by the energizing current of the battery. If the internal temperature of the battery rises above a critical value due to the resistance heat, the oxide structure of the cathode active material is collapsed to cause thermal runaway, thereby causing ignition or explosion of the battery.

On the other hand, in the secondary battery according to the present invention, when the electrode assembly moves toward the electrode terminal when an external shock is applied, the line-shaped groove on the outer surface of the battery case is ruptured, And the gas generated by decomposition of the electrolytic solution in the battery is discharged to the outside of the battery case through the broken line-shaped groove, thereby preventing the explosion due to the high pressure in the battery case, thereby improving the stability Structure.

The battery case may be a pouch-shaped case of a laminate sheet, and may have a structure in which an outer circumferential surface is thermally fused in a state in which the electrode assembly is embedded.

The laminate sheet may have a structure in which an outer covering layer, a barrier layer, and an inner sealant layer are sequentially laminated from the outer surface of the battery case to the inner surface thereof.

The outer coating layer is required to have excellent resistance from the external environment in order to protect the battery from the outside, and therefore, it is required to have excellent tensile strength and weatherability relative to the thickness. For example, a polyester resin such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT) and polyethylene naphthalate (PEN), a polyolefin resin such as polyethylene (PE) and polypropylene (PP) Polystyrene resins such as polystyrene, polyvinyl chloride resins, polyvinylidene chloride resins, and the like. These materials can be used singly or in combination of two or more kinds, and polyethylene terephthalate (PET), polyethylene naphthalate (PEN) and the like can be preferably used.

The barrier layer may be made of aluminum or an aluminum alloy so as to exhibit a function of improving the strength of the battery case in addition to the function of preventing the inflow or outflow of foreign matter such as gas or moisture. Examples of the aluminum alloy include Alloy No. 8079, 1N30, 8021, 3003, 3004, 3005, 3104, 3105, etc. These may be used alone or in combination of two or more. Among them, 8079, 1N30, 8021 and 3004 can be particularly preferably used as the metal foil of the barrier layer.

The inner sealant layer may be a polyolefin resin having a low heat absorbing property (thermal adhesiveness), low hygroscopicity to prevent penetration of an electrolyte solution, and not being swollen or eroded by an electrolytic solution. (CPP) may be used.

In one example, the outer coating layer comprises nylon or polyethylene terephthalate, the barrier layer comprises aluminum or an aluminum alloy, and the inner sealant layer comprises a non-oriented polypropylene. .

In the laminated sheet according to the present invention, the thickness of the outer coating layer is 5 to 40 占 퐉, the thickness of the barrier layer is 20 to 150 占 퐉, the thickness of each of the resin sealant layers is preferably 3 to 30 占 퐉, The total thickness of the sealant layer is preferably from 10 to 50 mu m. If the thicknesses are too thin, the barrier property between the outside and the inside of the battery case is lowered and the strength is lowered, which is undesirable. Conversely, if the thicknesses are too thick, not only the workability is deteriorated but also the thickness and weight of the battery case increase .

In one preferred example, the laminate sheet according to the present invention may be a high strength laminate sheet having an acicular penetration of at least about 7.0 kgf. A preferred example of such a high strength laminate sheet is one in which the barrier layer is made of an aluminum alloy and the outer coating layer is made of polyethylene naphthalate (PEN) or polyethylene terephthalate (PET) is applied to the outer surface of polyethylene / naphthalate ) Layer is provided.

It is preferable that the groove is formed to have a predetermined size and thickness that ruptures upon application of an external impact to cause ignition or explosion.

Specifically, the groove may be formed in a size of 20 to 80% based on the width of both sides of the battery case. If the groove is smaller than the above range, the grooves may not be broken even when an external impact is applied. On the contrary, when the ratio is larger than the above range, groove breakage may occur even when a small impact is not applied, which does not cause ignition and explosion.

Further, the groove may be formed at a depth of 20 to 70% based on the thickness of the battery case. If the depth of the groove is less than 20% based on the thickness of the battery case, the groove may not be ruptured even when an external impact is expected to ignite or explode. If the depth is 70% or more, In addition, the battery case may be broken during processing of the battery case for forming the groove, which is not preferable. For example, the width of the groove is preferably 0.1 to 0.2 mm.

The laminate sheet of the present invention includes an outer coating layer, a barrier layer, and an inner sealant layer, and at least one of the layers at a position corresponding to the groove may be formed to have a relatively thin thickness than a position other than the groove. That is, one or both of the outer coating layer, the barrier layer, and the inner sealant layer can be selected to reduce the thickness.

Preferably, in the laminate sheet, the thickness of the barrier layer corresponding to the groove is smaller than the thickness of the barrier layer corresponding to a position other than the groove. The thickness of the barrier layer corresponding to the groove may be, for example, 20 to 90% of the thickness of the barrier layer corresponding to the position other than the groove. If it is thinner than the above range, it is difficult to expect a blocking function and strength improvement for the material. On the contrary, if it is thicker than the above range, rupture is not easy and improvement of the safety of the battery is difficult to expect.

The groove may have a straight line structure parallel to the positive and negative terminals, for example. Such a groove can be formed much more easily than in the conventional art as described above, in which a plurality of convex grooves are formed on the outer surface of the battery case, or a convex portion is deformed into a linear pattern.

In another example, the groove may have an arc structure parallel to the cathode terminal and the cathode terminal. Specifically, the groove may be a gentle indentation structure of a semicircular structure in the inner side direction of the cell casing on a vertical section. Such an indented semicircular structure can suppress the rupture of the battery case during processing of the battery case for forming the groove, and is excellent in shape retention even in terms of structure.

The electrode assembly is not particularly limited as long as it has a structure in which a plurality of electrode tabs are interconnected to form an anode and a cathode. Preferably, the electrode assembly has a stacked structure and a stacked / folded structure. Details of the stacked / folded structure of the electrode assembly are disclosed in Korean Patent Application Laid-Open Nos. 2001-0082058, 2001-0082059 and 2001-0082060, the contents of which are incorporated herein by reference. As a reference.

The secondary battery according to the present invention can be preferably a lithium secondary battery, and is particularly applicable to a so-called lithium ion polymer battery in which a lithium-containing electrolyte is impregnated with an electrode assembly in the form of a gel.

The present invention also provides a device including the secondary battery as a unit cell. The secondary battery according to the present invention can be preferably used for a high output large capacity battery which requires a long service life and excellent durability, or a device including such a battery as a plurality of unit cells. The device can be used as a power source for electric vehicles, hybrid electric vehicles, electric motorcycles, electric bicycles, for example.

The structure and manufacturing method of such a device are well known in the art, and a detailed description thereof will be omitted herein.

As described above, the secondary battery according to the present invention has a structure in which linear grooves formed in parallel to the positive and negative terminals are ruptured on the outer surface of the battery case when an external impact is applied To prevent an internal short circuit due to the contact of the electrode lead or the electrode tab and the electrode assembly due to dropping of the battery or external physical impact and prevent the risk of ignition or explosion of the battery through discharge of the high pressure gas, .

1 is an exploded schematic view of one exemplary pouch type secondary battery;
2 is a plan perspective view of a secondary battery according to one embodiment of the present invention;
3 is a schematic cross-sectional view showing the side surface of Fig. 2;
4 is a schematic cross-sectional view of the structure in which the grooves of Fig. 3 are ruptured;
FIGS. 5 and 6 are enlarged views showing a region where grooves are formed in the battery case of FIG. 2. 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.

1 is an exploded schematic view of a pouch type secondary battery.

Referring to FIG. 1, a pouch-shaped battery cell 100 includes a pouch-shaped battery case 110, an electrode assembly 120 including an anode, a cathode, 160, and 130 are exposed to the outside. The electrode terminals 142 and 140 are electrically connected to the electrodes 160 and 130, respectively.

The battery case 110 includes a case body 114 including a concave shaped housing portion 116 on which the electrode assembly 120 can be placed and a cover 112 integrally connected to the body 114 have.

The electrode assembly 120 having a stacked or stacked / folded structure has a plurality of anode tabs 160 and a plurality of anode tabs 130 welded together and coupled together to the electrode terminals 142 and 140.

It is also possible to prevent short-circuiting between the heat fusing device and the electrode terminals 142 and 140 when the filler 118 of the case body 114 and the cover 112 are thermally fused by the heat fusing device, The insulating film 180 is attached to the upper and lower surfaces of the electrode terminals 142 and 140 in order to ensure the sealing property between the battery case 140 and the battery case 110.

The case body 114 and the cover 112 are composed of an outer coating layer 150, a barrier layer 152 and an inner sealant layer 154. The inner sealant layer 154 covers the outer surface of the case body 114, (Not shown) which is applied to the outer surface of the heat sink 112 by heat and pressure.

A sealing portion is formed by thermally fusing the abutment portion 118 of the case body 114 and the contact portion of the cover 112 in a state where the electrode assembly 120 impregnated with the electrolyte is seated in the accommodating portion 114.

FIG. 2 is a plan perspective view of a secondary battery according to an embodiment of the present invention.

2, the electrode assembly 220 is housed in the case body 210. The positive electrode terminal 222 and the negative electrode terminal 232 protrude from one end of the case body 210, 210 are formed on the outer surface of the electrode assembly 220 when the electrode assembly 220 moves in the direction of the anode terminal 222 and the anode terminal 232 or when a high pressure is generated in the battery, 230 are formed.

Fig. 3 is a schematic view showing one side section of Fig. 2, and Fig. 4 is a schematic view showing a structure in which grooves are ruptured in Fig.

Referring to FIGS. 3 and 4 together with FIG. 1, the groove 230 formed on the outer surface of the case body 210 is formed in a straight line parallel to the cathode terminal 222 and the cathode terminal 232, And has a thickness smaller than that of the case body 210.

When the electrode assembly 220 moves in the direction of the electrode terminals 222 and 232 in the case body 210 due to an external impact applied to the battery, the side surface of the case body 210 is pressed, And the low groove 230 is ruptured as shown in FIG.

Also, even if a gas is generated due to the decomposition of the electrolytic solution in a high-temperature state due to short-circuit and ignition, the gas can be discharged to the outside of the grooves 230 previously ruptured upon application of an external impact.

Figs. 5 and 6 are enlarged views showing a region where grooves are formed in the battery case of Fig. 2; Fig.

Referring to FIGS. 5 and 6 together with FIG. 2, the laminate sheet includes outer cover layers 250A and 250B, barrier layers 260A and 260B, and inner sealant layers 270A and 270B in an inner surface direction from the outer surface of the case body 210 ) Are stacked in this order.

5, the barrier layer 260A has a structure in which the groove 230A is positioned and the thickness of the portion is smaller than the thickness of the portion where the groove 230A is not located. In FIG. 6, the outer coating layer 250B and the barrier layer The groove 260A is formed such that the thickness of the groove 230A is smaller than the thickness of the portion where the groove 230A is not located.

Therefore, the grooves 230, 230A, and 230B having such a structure are ruptured when an external force is applied to the battery and the electrode assembly 220 is moved or a high pressure is generated therein, and the ruptured grooves 230, 230A, So that the safety of the battery is secured by preventing the risk of explosion of the battery.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.

Claims (16)

A laminate sheet pouch having a structure in which an electrode assembly having a structure in which a separator is interposed between an anode and a cathode and an outer cover layer, a barrier layer and an inner sealant layer are sequentially laminated from the outer surface to the inner surface of the battery case And the outer peripheral surface of the battery case is thermally fused.
The positive electrode terminal and the negative electrode terminal protrude from one end of the battery case. The outer surface of the battery case is connected to the electrode assembly when the electrode assembly moves toward the electrode terminal or when a high voltage is generated in the battery, Grooves are formed in parallel with the positive electrode terminal and the negative electrode terminal,
Wherein the laminate sheet is formed such that the thickness of the barrier layer at a position corresponding to the groove is relatively thinner than a position other than the groove. delete delete The method of claim 1, wherein the outer coating layer comprises nylon or polyethylene terephthalate, the barrier layer comprises aluminum or an aluminum alloy, the inner sealant layer comprises a non-oriented polypropylene And a secondary battery. The method according to claim 1, wherein the barrier layer is made of an aluminum alloy, and the outer coating layer is made of polyethylene naphthalate (PEN) or a layered structure of polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) Lt; / RTI > The secondary battery according to claim 1, wherein the thickness of the outer coating layer is 5 to 40 占 퐉, the thickness of the barrier layer is 20 to 150 占 퐉, and the thickness of the inner sealant layer is 10 to 50 占 퐉. The secondary battery according to claim 1, wherein the grooves are formed in a size of 20 to 80% based on widths of both sides of the battery case. The secondary battery according to claim 1, wherein the groove is formed at a depth of 20 to 70% based on the thickness of the battery case. The secondary battery according to claim 1, wherein a width of the groove is 0.1 to 2 mm. delete delete The secondary battery according to claim 1, wherein the groove has a straight line structure parallel to the cathode terminal and the cathode terminal. The secondary battery according to claim 1, wherein the groove has a circular arc structure parallel to the cathode terminal and the cathode terminal. The secondary battery according to claim 1, wherein the electrode assembly has a stacked or stacked-folded structure. The secondary battery according to claim 1, wherein the secondary battery is a lithium secondary battery. A device comprising a secondary battery according to claim 1.

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