KR100858807B1 - Pouched-type case and lithium secondary battery applying the same - Google Patents

Abstract

A pouch type case and a lithium secondary battery employing the same are disclosed. The present invention is a positive electrode plate, a separator, the battery unit is the negative electrode plate is wound; And, a positive electrode lead electrically connected to the positive electrode plate, and drawn from the positive electrode plate; and a negative electrode lead electrically connected to the negative electrode plate, drawn from the negative electrode plate; A case in which the battery part has a space part accommodated and a trimming part is formed at an edge of the sealed surface that is heat-sealed along the edge of the space part, wherein the edge of the sealed surface of the case maintains a gentle angle, and thus, an angled edge Negative scratches can be prevented beforehand.

Description

Pouch type case and lithium secondary battery employing same {Pouched-type case and lithium secondary battery applying the same}

1 is a plan view showing a conventional lithium secondary battery,

Figure 2 is an exploded perspective view showing a lithium secondary battery according to an embodiment of the present invention,

3 is an exploded perspective view illustrating the battery unit of FIG. 2;

4 is a perspective view of the combination of FIG.

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

20 Lithium secondary battery 21 Battery compartment

22.Anode plate 23 ... Anode plate

24 ... separator 25 ... positive lead

26.Negative lead 27.Protective tape

210 ... case 220 ... top case

230.Lower case 231..Space

232 ... airtight

The present invention relates to a lithium secondary battery, and more particularly, to a pouch type case having an improved structure of a corner portion of a case accommodating a battery unit, and a lithium secondary battery employing the same.

Typically, the rechargeable battery capable of charging and discharging is being actively researched by the development of portable electronic devices such as cellular phones, notebook computers, camcorders, and the like. Examples of such 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 3.6 V, which is three times better than a nickel-cadmium battery or a nickel-metal hydride battery, which is widely used as a power source for portable electronic devices, and has an excellent energy density characteristic per unit weight. It is rapidly expanding.

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. Lithium polymer batteries, which are in the spotlight in recent years, are manufactured in a flexible pouch type, and their shapes are relatively free. In addition, excellent safety and light weight will be advantageous for slimming and lightening portable electronic devices.

Referring to FIG. 1, the lithium secondary battery 10 includes a battery unit 11 and a case 12 which provides a space unit 15 in which the battery unit 11 is accommodated. 11, as is well known, consists of a positive electrode plate, a negative electrode plate, and a separator interposed therebetween.

The battery unit 11 is wound in a jelly-roll type in the state of being arranged in the order of a positive electrode plate, a separator, and a negative electrode plate, or a plurality of sheets are laminated in a stack type. In addition, the battery unit 11 is exposed to the outside of the case 12 in which the positive electrode lead 13 and the negative electrode lead 14 electrically connected to the respective electrode plates are sealed.

The case 12 is a pouch that can be bent freely by attaching a thin film of metal film and an insulating film on both sides thereof, unlike a cylindrical or rectangular shape formed of a metal film of a thick film in order to realize a thin and short sized electronic device. It is a pouched-type. The case 12 is provided with a space portion 15 to accommodate the battery unit 11, and is provided with a sealing surface 12a that is heat-sealed along the edge of the space portion 15.

The case 12 is aligned with the raw material of the thin plate, pressed using a mold to form a space portion 15 of a predetermined depth, and trimming (trimming) along the edge of the sealing surface (12a) desired It will be manufactured in the shape to be. At this time, the case 12 maintains an approximately rectangular shape. This is for optimizing upon accommodating the battery part 11 manufactured in a square shape.

In the lithium secondary battery 10 having the structure as described above, the polarizers having different polarities are disposed between the separators, and then the battery unit 11 is completed through a winding process or a laminating process. Is accommodated in the space 15. Next, the sealing surface 12a formed along the edge of the space portion 15 is heat-sealed and sealed.

However, the conventional lithium secondary battery 10 has the following problems.

First, the edge portion of the case 12, the sealing surface 12a is maintained at a right angle. Accordingly, scratches may occur when the lithium secondary battery 10 is assembled by the angled edges.

Secondly, after the assembly of the lithium secondary battery 10 is completed, a phenomenon occurs that a angular corner portion is caught when a protective element such as PTC is attached to the case 12 for safety.

Third, the sealing surface 12a of the case 12 is a portion that is folded to reduce the thickness of the battery, and the thickness at the angled edges is increased. This acts as a disturbing factor when minimizing the folded part while the battery becomes higher in capacity.

The present invention has been made to solve the above problems, it is an object of the present invention to provide a pouch-type case that prevents defects of the case in advance by forming a curvature at the corner of the case, and a lithium secondary battery employing the same. .

Pouch-type case according to an aspect of the present invention to achieve the above object,

The present invention relates to a case for providing a space in which a positive electrode plate, a negative electrode plate, and a battery unit made of a separator interposed therebetween are accommodated.                     

Upper case;

A lower case in which at least one surface is integrally bonded to the upper case; And

And a trimming part formed at an edge of a closed surface formed along an edge of the space part formed at any one of the upper and lower cases.

The trimming part may be a rounded curvature.

In addition, the trimming portion is characterized in that it is formed in a wavy form from two adjacent sides.

Further, the trimming part is formed by cutting a predetermined length from two corners of the corner to an adjacent side.

Lithium secondary battery employing a pouch type case according to another aspect of the present invention,

A battery unit in which a positive electrode plate, a separator, and a negative electrode plate are wound;

An anode lead electrically connected to the cathode plate and drawn from the anode plate;

A negative electrode lead electrically connected to the negative electrode plate and drawn from the negative electrode plate; And

And a case having a space portion in which the battery unit is accommodated, and a trimming portion formed at an edge of a sealing surface that is heat-sealed along the edge of the space portion.

2 illustrates a lithium secondary battery 20 according to an embodiment of the present invention, and FIG. 3 illustrates the battery unit 31 of FIG. 2.

2 and 3, the lithium secondary battery 20 includes a battery unit 21 and a case 210 accommodating the battery unit 21.

The battery unit 21 includes a positive electrode plate 22, a negative electrode plate 23, and a separator 24 interposed between the positive and negative electrode plates 22 and 23.

The positive electrode plate 22 includes a positive electrode current collector 22a made of a strip metal foil, and a positive electrode active material layer 22b coated on at least one surface of the positive electrode current collector 22a. The cathode current collector 22a is preferably an aluminum foil, which is a metal foil having excellent conductivity, and the cathode active material layer 22b is a composition in which a lithium oxide is mixed with a binder, a plasticizer, a conductive material, and the like. The positive electrode plate 22 has a positive electrode lead 25 attached to a positive electrode uncoated area 22c, and a protective tape 26 having a predetermined width is wrapped on an outer surface of an end side of the positive electrode lead 25. have.

The negative electrode plate 23 includes a negative electrode current collector 23 a made of a strip metal foil and a negative electrode active material layer 23 b coated on at least one surface of the negative electrode current collector 23 a. The negative electrode current collector 23a is preferably a copper foil having excellent conductivity, and the negative electrode active material layer 23b is a composition in which a negative electrode active material such as a carbon material is mixed with a binder, a plasticizer, a conductive material, and the like. A negative electrode lead 27 is attached to a negative electrode uncoated area 23c on the negative electrode plate 23, and a protective tape 28 is wrapped on the negative electrode lead 27 like the positive electrode lead 25. have.

The positive and negative electrode leads 25 and 27 are electrically connected to the surfaces of the positive and negative electrode uncoated parts 22c and 23c, and for this purpose, laser welding is performed on the positive and negative electrode uncoated parts 22c and 23c. It is attached so that electricity can be supplied by welding such as ultrasonic welding or conductive adhesive.

The case 21 includes an upper case 220 and a lower case 230 coupled with the upper case 220. The outer shape of the combined upper and lower cases 22 corresponds to the outer shape of the battery part 21 in order to minimize the volume and maintains a substantially rectangular shape.

At least one side of the upper and lower cases 220 and 230 are integrally in contact with each other, and the other sides are open to each other. The lower case 230 has a space 231 for accommodating the battery unit 21 therein, and a sealing surface 232 is formed along an edge of the space 231. The sealing surface 232 is a portion in which the battery part 21 is accommodated in the space part 231 and then sealed by heat fusion.

The battery unit 21 having the structure as described above may be wound in one direction in a state in which the positive electrode plate 22, the separator 24, and the negative electrode plate 23 are wound in one direction, so-called jelly-roll type. The jelly-roll type battery part 21 is a lithium secondary battery without a separate electrolyte, because a semiconductor-type polymer electrolyte is formed on a flexible polymer material, such as polyethylene (PE) separator 24. It would be possible to operate as a battery.

The battery unit 21 wound in the jelly-roll type is mounted in the lower case 230 in which the space 231 is provided. At this time, ends of the positive and negative electrode leads 23 and 27 electrically connected to the respective pole plates 22 and 23 of the battery unit 21 are drawn out of the case 210 to be sealed. After the battery unit 21 is seated, the battery unit 21 is sealed by applying a predetermined heat and pressure to the sealing surface 232 formed along the edge of the space 231. Accordingly, the lithium secondary battery 20 as shown in FIG. 4 is completed.

At this time, the sealing surface 232 is a portion extending integrally from the case 210 along the edge of the space portion 231, and maintains a predetermined width. In addition, the sealing surface 232 formed on the long side portion of the case 210 is a portion that is folded at least once to reduce the thickness of the battery.

In addition, trimming parts 233 are formed at corners of the sealing surface 232 to prevent scratches by the corners of the battery during the assembly process. The trimming unit 233 may be a rounding unit having a curvature treatment at a portion where adjacent two sides meet, or may be formed in a wave shape, or may be formed by cutting a predetermined length from a vertex to both sides. In the present exemplary embodiment, the trimming unit 233 is a rounding unit having a predetermined curvature treatment at the corner portion.

The case 210 having the trimming part 233 is punched to form the space part 231 using a metal film and a raw material of a pouch-type case coated with an insulating film on both sides thereof, and at least one side of the case 210 is formed. The upper and lower cases 220 and 230 joined together are molded. At this time, the trimming part 233 is formed during the trimming process of shaping the edges to remove the sharp edges at the corners of the sealing surfaces 232 of the upper and lower cases 220 and 230.

As described above, the pouch-type case of the present invention and the lithium secondary battery employing the same may be trimmed to smooth the angled corners of the case, and the following effects may be obtained.

First, as the edge portion of the sealing surface of the case maintains a gentle angle, it is possible to prevent the scratching phenomenon by the angled corner portion in advance.

Second, when assembling the lithium secondary battery, it is possible to eliminate the interference with the protective element attached for stability.

Third, when folding the sealing surface of the case, the obstacle to the folded portion is removed.

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 (8)

The present invention relates to a case for providing a space in which a positive electrode plate, a negative electrode plate, and a battery unit made of a separator interposed therebetween are accommodated. Upper case; A lower case in which at least one surface is integrally bonded to the upper case; And Pouch-shaped case comprising a; trimming portion formed in the corner portion of the sealing surface formed along the edge of the space formed in any one of the upper or lower case. The method of claim 1, The trimming part is a pouch-shaped case, characterized in that the curvature rounded portion. The method of claim 1, The trimming part is a pouch type case, characterized in that it is formed in a wavy form from two adjacent sides. The method of claim 1, The trimming part is a pouch-shaped case, characterized in that formed by cutting a predetermined length from the vertex of the corner to two adjacent sides. A battery unit in which a positive electrode plate, a separator, and a negative electrode plate are wound; An anode lead electrically connected to the cathode plate and drawn from the anode plate; A negative electrode lead electrically connected to the negative electrode plate and drawn from the negative electrode plate; And And a case having a space portion in which the battery portion is accommodated, and a trimming portion formed at an edge of a sealed surface that is heat-sealed along the edge of the space portion. The method of claim 5, And the trimming part is a curvature-rounded rounding part. The method of claim 5, The trimming part is a lithium secondary battery, characterized in that formed in a wavy form from adjacent two sides. The method of claim 5, The trimming part is a lithium secondary battery, characterized in that formed by cutting a predetermined length from two corners adjacent to the corner.

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