KR100778982B1 - Pouch case and pouch type secondary battery employing the same - Google Patents

Abstract

The present invention relates to a lithium secondary battery using lithium ions, and more particularly, to a pouch case having an improved structure to perform a hard case function and a pouch type secondary battery employing the same.

According to the present invention, by improving the structure of the pouch case, to protect the battery from external shock to improve the reliability of the pouch-type secondary battery, and to protect the battery without a separate hard case, the battery can be made thinner It is possible to meet various demands of the user, it is possible to remove the space occupied by the flange width, to provide a pouch case and a pouch type secondary battery having the same can provide a high capacity secondary battery.

Secondary Battery, Pouch Type,

Description

Pouch case and pouch secondary battery employing same {Pouch case and pouch type secondary battery employing the same}

1 is a perspective view showing a state before storing an electrode assembly in a conventional pouch case and sealing the pouch case;

Figure 2 is a perspective view showing a pouch case according to an embodiment of the present invention,

Figure 3a is a plan view showing a state in which the sealing portion is formed by heat-sealing the flange according to an embodiment of the present invention;

3B is a plan view of a pouch case showing a flange having some unsealed portions in accordance with one embodiment of the present invention;

3c is a plan view of a pouch case showing a state in which a wide sealing portion is formed by fusion of a flange according to an embodiment of the present invention;

4 is a cross-sectional view showing a pouch having the same height of the upper case and the lower case according to an embodiment of the present invention;

Figure 5 is a perspective view showing that the reinforcing member is attached to the inner surface of the pouch case according to an embodiment of the present invention,

Figure 6a is a rear view showing a state in which the heat-sealed after the electrode assembly is inserted into the pouch case according to an embodiment of the present invention;

Figure 6b is a rear view showing that both side flanges are fused to each other on one side of the pouch case according to an embodiment of the present invention,

FIG. 6C is a rear view showing that both side flanges are laminated and fused on one surface of a powder case according to one embodiment of the present invention; FIG.

Figure 6d is a rear view showing a form in which a long flange wraps the entire pouch body in accordance with an embodiment of the present invention;

Figure 6e is a partial perspective view showing that the long flange is in close contact with one side of the pouch case after wrapping the entire pouch body in accordance with an embodiment of the present invention.

* Explanation of symbols for the main parts of the drawings

10, 110, 210: 1st accommodating part 20, 120, 220: 2nd accommodating part

21, 121, 221a, 221b: groove 23, 123: front flange

17, 117a, 117b, 217a, 217b: side flange

30, 130, 230: electrode assembly 31: anode

33: separator 35: negative electrode

37: positive electrode tab 38: negative electrode tab

39: tape 100, 200: pouch case

111: inner layer film 112: interlayer film

113: outer layer film 114: sealing portion

The present invention relates to a lithium secondary battery using lithium ions, and more particularly, to a pouch case having a structure improved to perform a hard case function without a separate component and a pouch type secondary battery employing the same.

Secondary batteries are more economical than single-use batteries because they can be repeatedly used over and over again. In recent years, secondary batteries have a high capacity in a small volume and are widely used as power sources for portable electronic devices such as cellular phones, camcorders, and notebook computers. .

As such secondary batteries, nickel-cadmium batteries, nickel-metal hydride (Ni-MH) batteries, lithium secondary batteries, and the like have been developed and used. The battery is essentially provided with a positive electrode, a negative electrode and an electrolyte. In order to increase the area of the electrode in order to increase the output of the battery, first, the electrode in contact with the electrolyte is formed wide, and the short circuit between the two electrodes is prevented through the separator.

These secondary batteries are usually formed in cans. The cans are usually formed of metal. One side of the can of cylindrical or cuboid type is usually formed in an open state. Through this open portion, the electrode assembly and electrolyte are placed inside the can, and the can is closed with a cap assembly having a size and shape corresponding to the open side to form a sealed bare cell.

On the other hand, a lithium secondary battery uses a nonaqueous electrolyte due to the reactivity of lithium with moisture. The electrolyte may be in the form of a solid polymer containing lithium salts, and may be in a liquid form in which the lithium salt is dissociated in an organic solvent, or in a form in which a liquid electrolyte is impregnated into the separator. In particular, when using a solid polymer electrolyte or an electrolyte impregnated in the separator at the same time as the separator is less risk of leakage can be used as a case of the electrode assembly and the case of the electrolyte.

Pouches are advantageous as secondary batteries in that they are lighter, less bulky, and more flexible in the shape of the battery or in the device installation method than cans made primarily of metal.

In the pouch type secondary battery, the electrode assembly is inserted into the pouch and sealed, and an electric path connecting the electrode inside the pouch to the outside is secured by using a tab connected to the electrode. A bare cell formed by pouch sealing is connected to an accessory or structure such as a protecting circuit module (PCM) or a positive temperature coefficient (PTC) using a tab to form a core pack.

When the core pack is built into the hard case and combined, a completed hard pack battery is formed. The hard case may be formed using a polypropylene resin or the like without a separate circuit or conductor part inside, but there may be a separate accessory circuit or another conductor part inside the hard case depending on the characteristics of the device in which the battery is used.

Looking at the method of manufacturing a pouch battery having the above configuration, referring to Figure 1, a pouch covering the second receiving portion 20 and the groove 21 of the pouch in which the groove 21 to accommodate the electrode assembly is formed. The first receiving portion 10 of is formed. The groove 21 is formed through a press working or the like, and the groove may not be formed depending on the shape of the pouch. In the press working for forming the groove, a gas discharge groove (not shown) for degassing may be further formed in addition to the groove in which the electrode assembly 30 is accommodated.

The conventional electrode assembly 30 is formed of a jelly roll by winding a multilayer film stacked in the order of the anode 31, the separator 32, and the cathode 35 in a spiral shape. When winding up the jelly roll, a separator is added to the electrode surface exposed to the outside of the roll to prevent a short circuit between the positive electrode and the negative electrode. When the jelly roll is placed in the lower groove 21 of the pouch, the pouch is sealed by heating and pressing the edge 23 protruding outward from the groove portion in the form of a flange while keeping the front flange 23 in close contact. The pouch film usually consists of a plurality of functional films. In the pouch film composed of three layers, the intermediate layer metal film 13 is usually made of aluminum. The heat-adhesive layer 11 constituting the inner layer of the pouch film is usually made of a heat-adhesive material such as a cast polypropylene (CPP) layer, and protects the metal foil from the electrolyte and short-circuits between the anode, cathode, and electrode leads. prevent.

However, since the pouch case having the above structure is formed very thin, there is a limit to the case 50 protecting the electrode assembly 30 stored therein. In particular, in such a pouch case, the metal thin plate 13 added to maintain the strength as the case is only susceptible to external impact because its thickness is only a few tens of micrometers.

In addition, the hard case is used for the purpose of protecting the appearance of the pouch-type bare cell. In the case of injection molding the hard case, the thickness of the injection molded product is about 0.6 mm thick, resulting in a problem that the final battery product becomes large. When the battery is large, there is a problem that it is difficult to meet the various demands of the consumer because it is a factor that restricts the design of the electric device mounting the battery.

Accordingly, the present invention is to eliminate the above-mentioned conventional problems, an object of the present invention is to improve the structure of the pouch case, to protect the battery from external shock to improve the reliability of the pouch type secondary battery, The battery can be protected without a hard case, so the battery can be manufactured in a thin thickness, which can meet various demands of the users, and eliminate the space taken up by the flange width, thereby providing a high capacity secondary battery. And to provide a pouch type secondary battery having the same.

The present invention for achieving the above object,

A pouch case comprising a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate together to provide a sealed space for accommodating the formed electrode assembly.

A first receiving portion;

A second accommodating part disposed to face the upper first accommodating part and fused with the first accommodating part to form the enclosed space together with the first accommodating part;

A flange formed by fusing the first accommodating part and the second accommodating part,

It provides a pouch case, characterized in that any one of the two side flange of the flange is not drawn out of the electrode tab.

At least one of the first receiver and the second receiver includes a groove in which the electrode assembly is to be accommodated. The height of the first accommodating part and the second accommodating part may be the same.

At least one of the side flanges may have a length sufficient to wrap the electrode assembly more than once.

Both side flanges are formed such that, after being fused to each other at the first receiving portion, the second receiving portion or the side, the relatively long side flange covers the relatively short side flange. Preferably, both side flanges are fused together at the surface of the second receptacle.

The long side flange has a structure that wraps the entire pouch at least once.

The long side flange may wrap the entire electrode assembly and then adhere to the surface of the electrode assembly by fusion or tape.

The two side flanges may be fused to each other at the surface of the second receiving portion, and the long side flange may be bent in a direction of the short side flange to wrap the whole pouch body at least once or more, and then may be finished in a position where both side flanges are fused together. .

The pouch case is composed of a plurality of functional films. The functional film is composed of at least three layers, the outer layer film usually has a high mechanical strength, such as nylon, the inner protective film, the pouch interlayer is a metal film is usually formed of aluminum, the pouch film inner layer film is sequentially thermally bonded It is preferable that the heat-adhesive film having a property and serving as a sealing material is made of a polyolefin resin layer. Commonly used as the polyolefin resin layer is CPP (Casted Polypropylene).

The flange of the pouch can be sealed by thermal fusion. At this time, one side of the pouch flange may include a sealing portion that is widely fused. The pouch flange may be heat welded except for the portion that is bent when the flange on either side surrounds the pouch body.

A reinforcing member may be included on at least one surface of the pouch case.

The reinforcing member may be formed of a metal thin plate, or may be provided with a metal thin plate covered with an adhesive resin material, a fiber reinforced resin material, or an insulating tape.

For the second purpose of the present invention, the present invention

An electrode assembly having two electrodes and a separator,

Pouch case with the electrode assembly,

The pouch includes a bare cell coupled with a safety device including a protection circuit, and the pouch case provides a secondary battery, the structure of which is improved according to the present invention.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

Figure 2 is a perspective view showing a pouch case according to an embodiment of the present invention, Figure 3a is a plan view showing a state in which the sealing portion is formed by heat-sealing the flange according to an embodiment of the present invention, Figure 3b is an embodiment of the present invention 3 is a plan view of a pouch case showing a flange having a portion not partially sealed according to an example, FIG. 3c is a plan view of a pouch case showing a state in which a wide sealing part is formed by fusion of a flange widely according to an embodiment of the present invention, FIG. Cross-sectional view showing a pouch having the same height of the upper case and the lower case according to an embodiment of the present invention, Figure 5 is a perspective view showing that the reinforcing member is attached to the inner surface of the pouch case according to an embodiment of the present invention.

In order to compare the conventional pouch case, referring to FIG. 1, a method of manufacturing a conventional pouch secondary battery, the lower case 20 and the groove 21 of the pouch in which the groove 21 is formed to accommodate the electrode assembly are formed. The upper case 10 of the pouch to be covered is formed. When the conventional electrode assembly 30 is placed in the groove 21 of the second accommodating portion of the pouch, the pressurized side flange 17 protrudes outwardly from the groove portion in the form of a flange while the front flange 23 is in close contact with each other. To seal the pouch.

At this time, according to the conventional invention, a part of the molten polyolefin layer is squeezed out of the pouch by the external pressure for fusion in the process of facing the heat-adhesive polyolefin inner layer of the pouch to heat the pouch for sealing the pouch, In addition to damaging the appearance, the thickness of the fused polyolefin layer was reduced to reduce the sealing strength, and in some cases, the barrier layer, which is the next layer of the polyolefin layer, was exposed to cause an electrical short with the electrode or the outside.

According to the present invention, however, as shown in FIG. 3A, the front and side surfaces of the first accommodating part are folded over the second accommodating part to form a sealing part by thermal fusion. At this time, the flanges (117a, 117b) is formed on both sides long, even if the external pressure due to fusion is not part of the polyolefin layer does not stick out, the appearance is beautiful, and also there is no thickness limitation of the polyolefin layer hard adhesive portion Will form.

When the flanges of both sides are formed long, at least one or more flanges can cover the entire pouch body, thereby protecting the battery from external shock, thereby improving reliability of the pouch-type secondary battery, and without requiring a separate hard case. As the protection is possible, the thickness of the battery can be manufactured to be thin, which can meet various demands of the users and can eliminate the space occupied by the flange width, thereby providing a high capacity secondary battery.

According to another embodiment of the present invention, as shown in Figure 3b, the heat sealing of the pouch can be made except for the portion that is bent to facilitate wrapping the entire pouch with a flange of one side of the flange.

According to still another embodiment of the present invention, as shown in FIG. 3C, when the elongated flange is heat-sealed widely, a portion hardened by cooling may better protect the electrode assembly from external impact.

According to another embodiment of the present invention, as shown in FIG. 4, the height of the groove 121 of the first accommodating part of the pouch case and the groove 122 of the second accommodating part may be the same. As a result, the depths of the grooves 221a and 221b are lowered to the limit corresponding to the drawing processing depth, so that the capacity of the battery can be avoided. Also in this embodiment, the flanges 217a and 217b on both sides are formed long.

According to another embodiment of the present invention, as shown in FIG. 5, reinforcing members 175 and 176 may be included on at least one surface of the pouch case.

The reinforcing member may be formed of a metal thin plate, or may be provided with a metal thin plate covered with an adhesive resin material, a fiber reinforced resin material, or an insulating tape. Except in the case of self-adhesive like an insulating tape, it may be in close contact with the inner surface of the pouch case by thermocompression through the adhesive resin.

6A to 6D, FIG. 6A is a rear view illustrating a state in which a electrode assembly is inserted into a pouch case and then heat-sealed according to an embodiment of the present invention, and FIG. 6B is an embodiment of the present invention. Figure 6c is a rear view showing that both side flanges are fused to each other on one surface of the pouch case, Figure 6d is a rear view showing that both side flanges are laminated and fused on one surface of the pouch case, Figure 6d is Back view showing the form in which the long flange wraps the whole pouch body according to an embodiment of the present invention, Figure 6e shows that the long flange is in close contact with one surface of the pouch case after wrapping the entire pouch body according to an embodiment of the present invention Partial perspective view.

Here, both side flanges 117a and 117b in which the electrode tabs are not drawn out of the flange portion fused in the pouch may be collected in the first accommodating part 110 or the second accommodating part 120 of the pouch case. According to one embodiment of the pouch is collected on one side of the first receiving portion 110 and fused together, the double relatively long flange 117b covers the relatively short flange 117a, the electrode assembly is accommodated and sealed pouch (200) Wraps the whole. After wrapping the whole, the flange may be in close contact with any one surface of the first accommodating part 110, the second accommodating part 120, or the side surfaces 115a and 115b of the pouch case. This adhesion may be made by a method commonly used in the art, such as thermocompression or insulating tape. The result of the side flange wrapping the entire pouch is shown in Figure 6d.

As shown in FIG. 6D, the two side flanges are fused to each other at the surface of the second accommodating portion, and the long side flange is bent in the direction of the short side flange to wrap the whole pouch body at least once or more, and then the both side flanges are fused together. Closes in.

The pouch manufactured as described above may be directly used as a battery such as a PDA after combining a cap with upper and lower protective circuit boards.

As a result, the portion occupied by the flange can be reduced, and the capacity of the battery can be increased by the width thereof.

The flange may be brought into close contact with one side of the pouch and then additionally taped over it. The taping operation is made of a soft film or sheet to close the variable and easily deformable portion to make the entire pouch 200 in a stable and compact volume form.

The member used for taping uses a thin material to minimize the increase in the volume of the battery by taping, and is preferably limited to the necessary portion.

The taping operation makes the pouch case even harder and more robust to protect the electrode assembly from external shocks.

The electrode assembly may be a stacked electrode assembly in which a plurality of bi-cell stacks in which a positive electrode plate and a negative electrode plate are laminated through a separator are stacked.

According to the present invention, by improving the structure of the pouch case, to protect the battery from external shock to improve the reliability of the pouch-type secondary battery, and to protect the battery without a separate hard case, the battery can be made thinner It is possible to meet various demands of the user, it is possible to remove the space occupied by the flange width, to provide a pouch case and a pouch type secondary battery having the same can provide a high capacity secondary battery.

Claims (18)

A pouch case comprising a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate together to provide a sealed space for accommodating the formed electrode assembly. A first receiving portion; A second accommodating part disposed to face the first accommodating part, and fused with the first accommodating part to form the enclosed space together with the first accommodating part; A flange formed by fusing the first accommodating part and the second accommodating part, Pouch case, characterized in that any one of the two side flange of the flange is not drawn out the electrode tab. The method of claim 1, At least one of the first accommodating portion and the second accommodating portion includes a pouch case for receiving an electrode assembly. The method of claim 1, The height of the groove of the first accommodating portion and the groove of the second accommodating portion is the same. The method of claim 1, Pouch case, characterized in that at least one of the side flange has a length enough to wrap the electrode assembly more than once. The method of claim 1, A pouch case characterized in that the relatively long side flange is formed so as to cover the relatively short side flange after the two side flanges are fused to each other in the first receiving portion, the second receiving portion or the side. The method of claim 1, And the side flanges are mutually fused at the surface of the second receiving portion. The method of claim 1, The both side flanges are fused to each other at the surface of the second receiving portion, the long side flanges are bent in the direction of the short side flanges to wrap the entire body of the pouch at least one or more times, and then both side flanges are finished in the mutually fused position. Pouch case. The method of claim 1, Pouch case characterized in that the long side flange is made of a structure surrounding the entire pouch at least once. The method of claim 1, And the long side flange wraps the entire electrode assembly and is fused or taped to one surface of the electrode assembly. The method of claim 1, The pouch case comprises at least three layers of functional films. The method of claim 1, The pouch case is a pouch case, characterized in that the outer layer is made of a nylon layer, the pouch intermediate layer is an aluminum layer, the inner layer is made of a functional film comprising a polyolefin resin layer. The method of claim 11, Pouch case, characterized in that the polyolefin resin layer is CPP. The method of claim 1, Pouch case characterized in that the flange of the pouch is sealed by heat fusion. The method of claim 1, A pouch case, characterized in that it comprises a sealing portion in which one side of the pouch flange is fused widely. The method of claim 1, A pouch case, wherein the pouch flange is heat-sealed except for a portion that is bent when the flange of either side surrounds the pouch body. The method of claim 1, The pouch case is a pouch case, characterized in that it comprises a reinforcing member on at least one surface. The method of claim 16, And the reinforcing member is at least one of a metal thin plate, a metal thin plate covered with an adhesive resin material, a fiber reinforced resin material, and an insulating tape. An electrode assembly having two electrodes and a separator, Pouch case with the electrode assembly, A secondary battery comprising a bare cell in which a safety device including a protection circuit is coupled to the pouch, wherein the pouch case is the pouch case according to any one of claims 1 to 17.

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