KR20120072647A - Pouch for secondary battery and secondary battery using the same - Google Patents

Abstract

PURPOSE: An external material for a secondary battery and a pouch type secondary battery are provided to rapidly induce operation of a current interrupt device and to prevent safety accidents due to battery explosion. CONSTITUTION: An external material for a secondary battery comprises an upper exterior material(110), a lower part exterior material which combines with the upper exterior material in order for one or more battery cells to be accepted, and a notching part which is formed in the upper exterior material and/or the lower exterior material. The notching part is formed in the longitudinal direction of the exterior material or on outer surface of the exterior material. A pouch type secondary battery comprises a battery cell and the exterior material in which the battery cell is accepted.

Description

Exterior material and pouch type secondary battery for secondary battery {Pouch for secondary battery and Secondary battery using the same}

The present invention relates to a secondary battery packaging material and a pouch type secondary battery, which enables to operate a CID (current interrupt device) according to the expansion of the cell faster when a high temperature occurs due to the abnormal behavior of the battery cell.

In general, a battery is capable of supplying electrical energy including a cathode or a positive electrode and an anode or a negative electrode separated from each other by a separator and an electrolyte that enables ion transfer between the two electrodes. will be.

These batteries are classified into primary batteries (general cells) that are discarded after use and secondary batteries that can be reused through charging.

Recently, compact and lightweight electric / electronic devices such as cellular phones, notebook computers, camcorders, etc. have been actively developed and produced. These portable electric / electronic devices have built-in battery packs so that they can be operated even in a place where no separate power source is provided. The built-in battery pack includes at least one battery therein for outputting a predetermined level of voltage for driving the portable electric / electronic device for a period of time.

In consideration of economic aspects, the battery pack has recently adopted a secondary battery capable of charging and discharging. Representative secondary batteries include lithium secondary batteries such as nickel-cadmium (Ni-Cd) batteries, nickel-hydrogen (Ni-MH) batteries, lithium (Li) batteries, and lithium ion (Li-ion) batteries.

In particular, the lithium secondary battery has an operating voltage of 3.6 V, which is three times higher than that of a nickel-cadmium battery or a nickel-hydrogen battery, which is widely used as a power source for portable electronic equipment, and is rapidly expanding in terms of high energy density per unit weight. to be.

The lithium secondary battery has a structure including an electrode assembly having a positive electrode plate coated with a positive electrode active material, a negative electrode plate coated with a negative electrode active material, and a separator disposed between the positive electrode plate and the negative electrode plate. At this time, lithium oxide is mainly used as the positive electrode active material, and carbon material is used as the negative electrode active material. Generally, a battery using a liquid electrolyte is referred to as a lithium ion battery, and a battery using a polymer electrolyte is referred to as a lithium polymer battery, which is classified as a liquid electrolyte cell and a polymer electrolyte cell, depending on the type of the electrolyte. Moreover, although a lithium secondary battery is manufactured in various shapes, typical shapes include cylindrical shape, square shape, and pouch type.

Typically, the pouch type secondary battery of the secondary battery has a pouch case composed of a metal foil layer and a multi-layered film of a synthetic resin layer covering the same, when using this can significantly reduce the weight of the battery than a cylindrical or square secondary battery using a metal can Therefore, the weight reduction of the secondary battery has been developed toward the pouch type secondary battery.

However, the pouch type secondary battery generates a swelling phenomenon in which the pouch sheath is expanded due to gas generation during repeated charging, thereby causing deformation of the electrode assembly. When the deformation of the electrode assembly is severe, there is a problem in that a short occurs between the negative electrode plate and the positive electrode plate of the electrode assembly.

Accordingly, the secondary battery is provided with safety devices such as a PTC element, a thermal fuse, and a protective circuit module (PCM) and other battery accessories.

The safety devices are connected to the positive and negative terminals of the unit cell by a conductor structure called a lead, and when the voltage of the battery rises rapidly due to the high temperature rise or excessive charge and discharge of the battery, the current is blocked and the battery breaks. To prevent danger.

However, these safety devices remain in danger of malfunction when a circuit problem occurs. Moreover, the existing exterior materials remain firmly fixed even when a swelling phenomenon occurs in the state of accommodating the electrode assembly due to the fastening force of the fastening part. As a result, it may interfere with the operation of the CID (Current Breaker).

The present invention is to solve this problem, an object of the present invention is to make the operation of the current interruption device to be made more quickly by easily breaking the packaging material surrounding it when the battery cell abnormal behavior.

In order to solve the above problems, in the present invention, the upper exterior material; A lower outer cover material coupled to the upper outer cover material so that at least one battery cell is accommodated therein; There is provided a secondary battery packaging material including a notching portion formed on at least one of the upper and lower packaging materials.

In addition, in the present invention; An upper exterior member and a lower exterior member coupled to accommodate the battery cell; A pouch type secondary battery including a notching portion formed on at least one of the upper and lower exterior materials is also provided.

The notching portion is formed in the longitudinal direction of the packaging material.

The upper exterior member and the lower exterior member are respectively provided with an upper fastening portion and a lower fastening portion which are fastened to each other, one of the upper fastening portion and the lower fastening portion protrudes a fastening protrusion, and the other fastening hole is formed.

As described above, according to the present invention, when the cell performs normal operation, the exterior material surrounding the battery cell remains tightly sealed, but when the battery cell is abnormally behaving, it is formed on the upper and lower exterior materials of the exterior material. The notching part is easily broken, thereby quickly inducing the operation of the current interrupt device, thereby preventing a safety accident due to the explosion of the battery.

1 is a perspective view showing a secondary battery according to the present invention.
Figure 2 is an exploded perspective view showing a secondary battery according to the present invention.

Hereinafter, a preferred embodiment of the secondary battery packaging material and pouch type secondary battery according to the present invention will be described in detail.

A secondary battery is a battery using an electrochemical reaction generated between an electrolyte and an electrode when a positive electrode and a negative electrode are inserted into an electrolyte material and the positive electrode and the negative electrode are connected to each other. Unlike conventional primary batteries, energy consumed in electrical and electronic products Since the battery can be recharged and recharged by a charger and can be repeatedly used, it is showing rapid growth with wireless electrical and electronic products.

In recent years, there is a high demand for square cells and pouch cells that can be applied to products such as mobile phones with a thin thickness in terms of shape of the battery. The demand for secondary batteries is high.

One of the major research tasks in such secondary batteries is to improve safety. In general, lithium secondary batteries are caused by high temperature and high pressure inside the battery, which may be caused by abnormal operating conditions of the battery, such as internal short, allowable current, state of charge exceeding voltage, exposure to high temperature, dropping, etc. May cause the battery to explode.

Accordingly, the present invention provides an exterior material that can ensure the safety of the secondary battery described above. 1 and 2 illustrate a state in which the battery cell 200 is accommodated in the exterior material 100 according to the present invention, respectively.

According to this, the exterior member 100 of the present invention is divided into a lower exterior member 120 that can accommodate a battery cell, and an upper exterior member 110 having a cover shape coupled to an upper side of the lower exterior member 120.

At this time, each of the outer packaging material is made of a rectangular, both ends of the upper outer packaging material 110 and the lower outer packaging material 120 in the width direction so that the upper outer packaging material 110 and the lower outer packaging material 120 can be sealed in contact with the secondary battery assembly process. Each of the upper fastening portion 111 and the lower fastening portion 121 is bent in a direction corresponding to each other.

That is, the upper coupling portion 111 of the upper outer case 110 is bent downward and the lower coupling portion 121 of the lower outer case 120 is bent upward to wrap the battery cell 200 and the upper coupling portion 111 The lower coupling portion 121 is combined to overlap each other, thereby having a pouch shape as a whole.

On the other hand, when the battery cell performs a normal operation, the exterior material needs to be firmly fastened. Therefore, a fastening protrusion protrudes from the fastening portion located inside the upper and lower fastening portions, and a fastening hole is formed in the fastening portion located outside. In the drawing of the present embodiment, since the lower fastening portion 121 is located inside the upper fastening portion, the fastening protrusion 122 is formed at the lower fastening portion 121 and the fastening hole 112 is connected to the upper fastening portion 111. Is formed. Therefore, the upper fastening part 111 and the lower fastening part 121 may maintain a firm coupling state by the coupling of the fastening hole 112 and the fastening protrusion 122.

However, in case of high temperature caused by abnormal behavior of the cell, the fastening force of the exterior material should be sharply weakened so that the CID operation can be performed quickly. To this end, in the present invention, notching portions 113 and 123 are formed in at least one of the upper and lower exterior materials 110 and 120.

At this time, the notching portions 113 and 123 are preferably formed in a longitudinal direction in a rectangular packaging material. That is, the notching portion is formed in a direction parallel to each of the fastening portions, because the breakage of the packaging material due to the bending load is easy.

If the notching portion is formed in the width direction of the sheathing material, its length is relatively short, and since the fastening portions are bent at each end of the width direction, the secondary moment of inertia of the cross section increases. Because of this, the width direction of the packaging material can withstand the bending load better, so that the breaking of the packaging material is not easy.

In addition, the notching portion is preferably formed on the outer surface of each exterior material. When the swelling phenomenon occurs due to the abnormal behavior of the battery cell, the exterior member is subjected to a bending load. At this time, a tensile stress is applied to the outer surface of the exterior member and a compressive stress is applied to the inner surface. In this case, in order for the breakage of the exterior material to proceed effectively, the tensile stress acts on the notching portion so that the crack of the notching portion can be developed. However, when the compressive stress acts on the notching portion, the crack is difficult to progress.

As described above, the secondary battery according to the present invention maintains a state in which the upper exterior member 110 and the lower exterior member 120 are firmly coupled to each other during normal operation. However, during abnormal cell behavior, the temperature rises rapidly and gas is released to cause swelling. When the swelling phenomenon is maximized as described above, at least one or more notching portions 113 and 123 of the upper exterior member 110 and the lower exterior member 120 are broken, thereby inducing a CID operation quickly, thereby causing a safety accident due to explosion of the battery. Can be prevented in advance.

The present invention also provides a pouch-type secondary battery comprising the exterior material as described above.

1 and 2, the pouch type secondary battery of the present invention includes a battery cell 200 having a positive electrode, a negative electrode, and a separator, and an exterior material 100 surrounding the battery cell.

The positive electrode is a part of the positive electrode active material coated on the positive electrode current collector, the positive electrode current collector is usually formed to a thickness of 3 to 500 ㎛. Such a positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical change in the battery. For example, the positive electrode current collector may be formed on the surface of stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel. The surface-treated with carbon, nickel, titanium, silver, etc. can be used. The positive electrode current collector may increase the adhesion of the positive electrode active material by forming minute unevenness on its surface, and may be in various forms such as film, sheet, foil, net, porous body, foam, and nonwoven fabric.

The negative electrode is manufactured by coating and drying a negative electrode active material on the negative electrode current collector, and the negative electrode current collector is usually made of a thickness of 3 to 500 ㎛. Such a negative electrode current collector is not particularly limited so long as it has conductivity without causing chemical change in the battery. For example, the negative electrode current collector may be formed on the surface of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper, or stainless steel. Surface-treated with carbon, nickel, titanium, silver and the like, aluminum-cadmium alloy and the like can be used. The negative electrode current collector may also form fine irregularities on its surface to increase the adhesion of the negative electrode active material.

The exterior member 100 is divided into a lower exterior member 120 capable of accommodating a battery cell, and an upper exterior member 110 having a cover shape coupled to an upper side of the lower exterior member, and the upper exterior member 110 and the lower exterior member 120. The upper fastening portion 111 and the lower fastening portion 121 are bent at the side surfaces thereof, and the configuration thereof is substantially the same as described above, and thus detailed description thereof will be omitted.

Meanwhile, an electrode lead (anode lead and cathode lead) 210 electrically connected to the battery cell 200 protrudes a predetermined amount to the outside of the exterior material 100.

That is, the two electrode leads 210 are electrically connected to electrode tabs (not shown) extending from each electrode plate (not shown) of the battery cell by welding or the like, and a part of the electrode leads 210 of the exterior member 100 are separated from each other. It was exposed to the outside.

The positive lead and the negative lead may be located side by side in the same direction in the packaging material, or may be located in opposite directions as shown in the drawing.

According to the secondary battery configured as described above, when the battery cell performs a normal operation, it maintains a tightly coupled state between the upper and lower outer material, but at least one of the upper and lower outer material notching during the abnormal behavior of the battery cell. The part breaks easily. Accordingly, it is possible to induce the operation of the current interrupt device quickly to prevent the accident caused by the explosion of the battery in advance.

100; Exterior material
110; Upper exterior material
111; Upper part
112; Fastener
113; Notching department
120; Bottom exterior material
121; Lower part
122; Fastening protrusion
123; Notching department
200; Electrode Assembly
210; Electrode Lead

Claims (9)

Upper exterior material;
A lower outer cover material coupled to the upper outer cover material so that at least one battery cell is accommodated therein;
Secondary battery packaging material comprising a notching portion formed in at least one of the upper and lower exterior materials.
The method of claim 1,
The notching part is a secondary battery packaging material, characterized in that formed in the longitudinal direction of the packaging material.
The method of claim 1,
The notching part is a secondary battery packaging material, characterized in that formed on the outer surface of the packaging material.
The method of claim 1,
The upper exterior material and the lower exterior material is a secondary battery packaging material, characterized in that the upper fastening portion and the lower fastening portion which are respectively fastened to each other.
The method of claim 4, wherein
Any one of the upper fastening portion and the lower fastening portion protrudes a fastening protrusion, the other is a secondary battery packaging material, characterized in that the fastening hole is formed.
Battery cell;
An upper exterior member and a lower exterior member coupled to accommodate the battery cell;
A pouch type secondary battery comprising a notching portion formed on at least one of the upper and lower exterior materials.
The method of claim 6,
The notching part of the pouch type secondary battery, characterized in that formed in the longitudinal direction of the packaging material.
The method of claim 6,
A pouch type secondary battery, wherein the upper exterior member and the lower exterior member are provided with an upper fastening part and a lower fastening part which are fastened to each other.
The method of claim 8,
Pouch-type secondary battery, characterized in that any one of the upper fastening portion and the lower fastening portion protrudes a fastening protrusion, the other is a fastening hole is formed.

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