KR100428974B1 - Secondary battery applying safety device - Google Patents

Abstract

Disclosed is a secondary battery employing a safety device. The present invention includes a battery unit stacked in plural sheets in order of a positive electrode plate, a separator, and a negative electrode plate; and a case formed of a multilayered layer to provide a space part in which the battery unit is accommodated. A pouch comprising an inner layer made of resin, an outer layer made of a polymer resin formed as the outermost layer with respect to the battery part, and an intermediate layer made of a metal sheet having at least one opening formed therebetween. Since opening holes are formed in at least one layer in the aluminum layer having a double-layer structure forming the intermediate layer of the case, breakage occurs first in this portion during swelling of the battery, thereby improving safety.

Description

Secondary battery employing safety devices {Secondary battery applying safety device}

The present invention relates to a secondary battery, and more particularly, to a secondary battery employing a safety device that improves the stability of the battery by breaking at a predetermined portion when the case is expanded due to overcharging of the battery.

Secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-hydrogen batteries, and lithium secondary batteries. Among them, the lithium secondary battery has an operating voltage of 3.6V and is three times better than the nickel-cadmium battery or nickel-metal hydride battery, which is widely used as a power source for electronic devices, and has an excellent energy density per unit weight. have.

Lithium secondary batteries can be classified into liquid electrolyte batteries and polymer electrolyte batteries according to the type of electrolyte. Generally, a battery using a liquid electrolyte is called a lithium ion battery, and a battery using a polymer electrolyte is called a lithium polymer battery.

The lithium secondary battery may be manufactured in various forms, and typical shapes include cylindrical and square shapes mainly used in lithium ion batteries. Li-polymer batteries, which are in the spotlight in recent years, are made of flexible materials, and their shapes are relatively free. In addition, excellent safety and light weight can be said to be advantageous for slimmer and lighter portable electronic devices.

1 illustrates an example of such a lithium polymer battery 10.

Referring to the drawings, the battery 10 includes a battery part 11 in which a plurality of separators interposed between a positive electrode plate and a negative electrode plate and interposed therebetween, and electrodes drawn out from respective electrode plates of the battery part 11, respectively. And a tab 12 and an electrode terminal 13 electrically connected to the electrode tab 12. The battery unit 11 is mounted in a case 14 provided with a space for accommodating the battery unit 11, and the case 14 is joined to open part of the upper and lower cases.

The battery 10 having the structure as described above is firmly formed by mounting the battery unit 11 in the case 14, injecting a predetermined amount of electrolyte, and then applying heat and pressure to the contact surface of the case 14. Sealed to complete.

By the way, the conventional battery 10 has the following problems.

When the internal pressure of the battery 10 increases due to an overcharge lamp, a so-called swelling phenomenon occurs in which the pouch-shaped case 14 expands. When the swelling phenomenon occurs, the battery unit 11 is deformed. Accordingly, while the case 14 in which the battery unit 11 is contracted is pressed, the battery 10 may locally generate a short circuit.

In addition, when overcharged or exposed at high temperatures, a gas having a high ignition potential is generated inside the case 14 due to the reaction between the electrolyte and the active material layer of the electrode plate or the decomposition of the electrolyte and the active material layer itself. ) May cause fire or explosion.

Therefore, the battery 10 will need a safety device that can prevent the bursting or explosion in advance by quickly blocking the swelling phenomenon when the internal pressure is above a certain level.

The present invention is to solve the above problems, to provide a secondary battery employing a safety device that induces breakage at a predetermined portion of the case during the swelling of the battery to quickly discharge the gas in the battery to the outside to improve safety. The purpose is.

1 is a schematic view showing a conventional secondary battery,

Figure 2 is an exploded perspective view showing a part of the secondary battery in accordance with an embodiment of the present invention partially expanded;

3 is a plan view schematically illustrating the features of the secondary battery of FIG. 2;

4 is a perspective view according to a first embodiment partially showing features of the secondary battery of FIG. 2;

5A is a perspective view according to a second embodiment showing features of the secondary battery of FIG. 2;

FIG. 5B is a perspective view according to a third embodiment illustrating features of the secondary battery of FIG. 2; FIG.

5C is a perspective view according to a fourth embodiment illustrating features of the secondary battery of FIG. 2.

<Brief description of symbols for the main parts of the drawings>

20 ... battery 21 ... battery

22 Case 23 Positive plate

24 ... cathode plate 25 ... separator

210 ... first aluminum layer 220 ... second aluminum layer

230.Corrosion resistant floor 240.Heater floor

250.Exterior layer

In order to achieve the above object, the secondary battery employing a safety device according to an aspect of the present invention,

A battery unit stacked in plural in order of a positive electrode plate, a separator, and a negative electrode plate;

In the secondary battery employing a safety device provided with; a multi-layer case for providing a space portion to accommodate the battery unit,

The case is formed between an interior layer made of a polymer resin formed as an innermost layer with respect to the battery unit, an exterior layer made of a polymer resin formed as an outermost layer with respect to the battery unit, and formed between the interior and exterior layers. And an intermediate layer made of a metal sheet having at least one opening hole formed therein.

In addition, the intermediate layer is a plurality of metal thin plates are mutually thermally compressed, at least one of the metal thin plate is characterized in that the opening hole is formed so that the thickness is thinner than other parts in order to cause the breakage preferentially when the internal pressure of the battery rises It is done.

Further, the metal thin plate is characterized in that the aluminum.

In addition, the interior layer is characterized in that a bilayer in which a polyamide-based resin and a resin such as ethylene-vinyl alcohol copolymer are sequentially laminated.

Further, the lower surface of the inner layer further includes a heater chamber layer made of any one selected from ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-ethyl acrylate copolymer, and ethylene-methacrylate copolymer. Characterized in that formed.

In addition, the outer layer is made of any one material selected from polyamide, high density polyethylene, polyethylene terephthalate, and polypropylene.

Hereinafter, a secondary battery employing a safety device according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

2 illustrates a lithium polymer battery 20 according to an embodiment of the present invention, and FIG. 3 is a plan view of FIG. 2.

Referring to the drawings, the battery 20 includes a battery unit 21 and a case 22 in which the battery unit 21 is accommodated.

The battery unit 21 includes a positive electrode current collector, a positive electrode plate 23 made of a positive electrode active material layer coated on at least one surface of the positive electrode current collector, a negative electrode current collector, and a negative electrode active material layer formed on at least one surface of the negative electrode current collector. And a separator 25 interposed between the negative electrode plate 24 and the positive electrode and negative electrode plates 23 and 24 to electrically insulate them from each other. The battery unit 21 is laminated in plural in order of the positive electrode plate 23, the separator 25, and the negative electrode plate 24.

The positive electrode tabs 26 and the negative electrode tabs 27 are drawn out from one edges of the positive and negative electrode plates 23 and 24, respectively, and are connected to each other so as to be able to conduct electricity to each of the electrode plates 23 and 24. The positive and negative electrode tabs 26 and 27 are welded to the positive and negative electrode terminals 28 and 29 which are electrically connected to external terminals at their ends.

The case 22 accommodating the battery unit 21 includes an upper case 22a and a lower case 22b, and the upper and lower cases 22a and 22b are integrally bonded to at least one edge surface thereof. And the remaining sides are openable. In addition, at least one of the upper and lower cases 22a and 22b is provided with a space part 200 in which the battery part 21 can be accommodated. Surfaces formed along the edges of the space part 200 serve as a sealing part to provide a thermo-compressed surface for sealing the upper and lower cases 22a and 22b after the battery part 21 is mounted. Done.

According to a feature of the present invention, the case 22 has a multi-layered structure, and an opening hole 260 is formed in any one of the multilayers.

That is, the case 22 is a metal layer of a double layer, for example, the first aluminum layer 210, the second aluminum layer 220, and the corrosion-resistant layer 230 formed sequentially inside the first aluminum layer 210. ), A heater seal layer 240, and an exterior layer 250 formed outside the second aluminum layer 220.

In more detail, as shown in FIG.

Layers with different physical properties are bonded to the case 22 so that the battery unit 21 is protected from the outside and breakage is rapidly generated at any one part during swelling.

As the intermediate layer of the case 22, a first aluminum layer 210 and a second aluminum layer 220 attached to an upper surface of the first aluminum layer 210 are disposed. The first and second aluminum layers 210 and 220 have an appropriate thickness to maintain the appearance of the case 22, and serve as a waterproof layer that prevents penetration of moisture from the outside, and prevents leakage of the electrolyte solution. To this end, the first and second aluminum layers 210 and 220 may have a thickness of about 50 to 300 micrometers, and may maintain moldability when manufacturing a thin plate of substantially 70 to 200 micrometers, and reduce manufacturing costs. It can be said to be advantageous.

In this case, an opening hole 260 is formed in the first and second aluminum layers 210 and 220 so that the battery 20 may be preferentially broken at the other part during swelling. The opening 26 may be formed in the first and second aluminum layers 210 and 220 through a separate manufacturing process.

That is, the first aluminum layer 210 is a thin plate on which opening holes 260 having a predetermined shape are formed. The opening 260 is preferably formed in a portion where the battery 20 deforms the most when the battery 20 swells. On the other hand, the second aluminum layer 220 is a thin plate that does not have an opening. When the first aluminum layer 210 having the opening hole 260 and the second aluminum layer 220 having no opening hole are attached to each other through a process such as thermocompression bonding, the opening hole 260 is formed. The part is sealed by the second aluminum layer 220, it is possible to serve as a notch portion.

The portion in which the opening hole 260 is formed is relatively thinner than other portions of the first and second aluminum layers 210 and 220. Accordingly, it can be said that the stress is concentrated in this region when the case 22 is expanded. In this case, the opening hole 260 may be formed in various shapes as well as a simple circular or square.

A multi-layered built-in layer is formed in the inner direction of the case 22, which is the lower surface of the intermediate layer made of the first and second aluminum layers 210 and 220.

That is, the corrosion resistant layer 230 is formed on the lower surface of the first aluminum layer 210. The corrosion resistant layer 230 is formed so as to prevent the electrolyte in the case 22 from being buried in the first and second aluminum layers 210 and 220 when swelling. The corrosion resistant layer 230 preferably has a structure of a double layer in which a polyamide-based resin and a resin such as ethylene-vinyl alcohol copolymer are sequentially stacked.

The heater chamber layer 240 is formed at the innermost layer, which is the lower surface of the corrosion resistant layer 230. The heater chamber layer 240 is preferable to select a material that can withstand a high internal temperature during operation of the battery 20 can prevent the deterioration of the battery. As the heater chamber layer 240, any one material selected from an ethylene-acrylic acid copolymer, an ethylene-methacrylic acid copolymer, an ethylene-ethyl acrylate copolymer, and an ethylene-methacrylate copolymer may be used.

At this time, the sum of the thicknesses of the corrosion-resistant layer 230 and the heater chamber layer 240, which is a built-in layer, is about 20 to 70 micrometers. I will say.

The outer layer 250 is formed in an outer direction of the case 22, which is the upper surface of the intermediate layer. The exterior layer 250 should prevent cracks from occurring on the outer surface of the battery 20 and should facilitate the overall molding. As the exterior layer 250, it is advantageous to use any material selected from polyamide, high density polyethylene, polyethylene terephthalate, and polypropylene. In addition, the thickness of the exterior layer 250 is relatively thin compared to the thickness of the intermediate layer and the interior layer, and is approximately 15 micrometers or more. This may be said to be the minimum thickness that can enhance the formability of the case 22.

5A to 5C illustrate an intermediate layer in which opening holes are formed according to another embodiment of the present invention.

Here, the same reference numerals as in the above-described drawings indicate the same members having the same function.

Referring to the drawings, the intermediate layer is a thin aluminum sheet. That is, the first aluminum layer 210 and the second aluminum layer 220 directly attached to one surface of the first aluminum layer 210 are formed. The corrosion resistant layer and the heater chamber layer are sequentially stacked on the inside of the intermediate layer, and the exterior layer is stacked on the outside to form a case.

Opening holes 561 to 563 are formed in the first and second aluminum 210 and 220 at the central point where the case is most swelled. The openings 561 to 563 may be formed in the first aluminum 210 in various shapes such as a predetermined shape, for example, a “Y” shape, an “I” shape, or an “X” shape.

After the opening holes 561 to 563 are formed in the first aluminum 210, and then the second aluminum 220 is thermocompressed on one surface of the first aluminum 210, the opening holes 561 to 563 are formed. The formed portion serves as a notch portion formed relatively thinner than other portions.

The battery 20 having the structure as described above is completed by mounting the battery unit 21 in the pouch-shaped case 22 and sealing the sealing surfaces of the upper and lower cases 22a and 22b by thermal compression. . When the swelling is generated due to overcharging, the completed battery 20 may be said to be capable of operating as a safety device by preferentially breaking the part in which the opening hole 260 formed in the intermediate layer constituting the case 22 is broken. .

As described above, the secondary battery employing the safety device of the present invention forms an opening hole in at least one layer in an aluminum layer having a double layer structure forming the intermediate layer of the case in the form of a pouch. The break occurs first at, which improves safety. As a result, the battery can prevent explosion and fire.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (9)

A battery unit disposed in the order of a positive electrode plate, a separator, and a negative electrode plate; It includes; a case having a multi-layer structure providing a space portion for accommodating the battery portion, The case is formed between a built-in layer made of a polymer resin formed as an innermost layer with respect to the battery unit, an outer layer made of a polymer resin formed as an outermost layer with respect to the battery unit, and a plurality of built-in and outer layers. An intermediate layer having at least one opening hole formed so as to have a thickness thinner than other parts so that the two metal thin plates are mutually thermo-compressed, and at least one metal thin plate may be preferentially broken when the internal pressure of the battery increases. Secondary battery employing a safety device comprising a. delete The method of claim 1, The metal sheet is a secondary battery employing a safety device, characterized in that the aluminum. The method of claim 1, The thickness of the intermediate layer is a secondary battery employing a safety device, characterized in that 50 to 300 micrometers. The method of claim 1, The built-in layer is a secondary battery employing a safety device, characterized in that the double layer of a polyamide-based resin and a resin such as ethylene-vinyl alcohol copolymer sequentially laminated. The method of claim 5, The lower surface of the interior layer is further formed with a heater chamber layer made of any one selected from ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-ethyl acrylate copolymer, or ethylene-methacrylate copolymer. Secondary battery employing a safety device characterized in that. The method of claim 6, The sum of the thickness of the built-in layer and the heater chamber layer is a secondary battery employing a safety device, characterized in that 20 to 70 micrometers. The method of claim 1, A secondary battery employing a safety device, characterized in that the outer layer is made of any one material selected from polyamide, high density polyethylene, polyethylene terephthalate, and polypropylene. The method of claim 8, The thickness of the outer layer is a secondary battery employing a safety device, characterized in that more than 15 micrometers.