KR101243550B1 - Secondary battery improved safety characteristic using fixing element - Google Patents

Abstract

In the secondary battery according to the present invention, the electrode assembly is fixed to the battery case by using a fixing member, thereby preventing the flow of the electrode assembly in the case during external shock such as battery drop, thereby ensuring the stability of the battery.

Description

Secondary battery with improved stability using fixing member {SECONDARY BATTERY IMPROVED SAFETY CHARACTERISTIC USING FIXING ELEMENT}

1 is an exploded perspective view of a pouch type secondary battery according to an embodiment of the present invention;

2A is a plan view of a secondary battery in a state excluding the upper case of FIG. 1;

2B is a cross-sectional view of the secondary battery shown in FIG. 1;

3 to 5 are plan views of secondary batteries in a state except the upper case according to each embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

10: upper case 20: lower case

21: storage space 23: front flange

25: side flange portion 30: electrode assembly

40: battery part 70, 70 ', 70 ", 170: fixing member

The present invention relates to a secondary battery, and more particularly, by fixing an electrode assembly to a battery case using a fixing member, thereby preventing the flow of the electrode assembly in the case during external shock such as a battery drop, thereby ensuring the stability of the battery. It is about.

In general, a secondary battery refers to a battery that can be charged and discharged, unlike a primary battery that cannot be charged, and is widely used in the field of advanced electronic devices such as a cellular phone, a notebook computer, a camcorder, and the like. In particular, lithium secondary batteries have an operating voltage of 3.6V, which is three times higher than nickel-cadmium batteries or nickel-hydrogen batteries, which are widely used as electronic equipment power sources, and are rapidly increasing in terms of high energy density per unit weight.

Lithium secondary batteries use nonaqueous electrolytes because of their reactivity with lithium. This electrolyte may be a solid polymer containing lithium salts, or may be a liquid phase in which lithium salts dissociate in an organic solvent. When the lithium secondary battery is classified according to the type of electrolyte, it may be classified into a lithium metal battery using a liquid electrolyte, a lithium ion battery, and a lithium ion polymer battery using a polymer solid electrolyte. Lithium-ion polymer battery is a lithium-ion polymer battery that uses a fully solid lithium ion polymer battery containing no organic electrolyte at all according to the type of polymer solid electrolyte and a gel polymer electrolyte containing organic electrolyte. Can be divided.

In the case of a completely solid lithium ion polymer battery, there is no problem of leakage of the organic electrolyte. In the case of a gel-type lithium ion polymer battery containing an organic electrolyte, leakage of the organic electrolyte may occur, but the leakage of the electrolyte may be prevented in a simpler form as compared with a lithium ion battery using a liquid electrolyte. For example, a lithium ion polymer battery may use a multilayer film pouch in place of a metal can of a lithium ion battery.

In the case of using a multilayer film pouch, the weight of the battery can be significantly reduced compared to using a metal can. The polymer film forming the inner layer of the pouch film protects the metal foil of the intermediate layer from the electrolyte and prevents short circuit between the first electrode, the second electrode, and the electrode tabs.

The pouch type secondary battery includes an electrode assembly that generates a predetermined current, and a pouch case that surrounds and seals the electrode assembly. The electrode assembly includes a battery part, an electrode tab, and a protective member. The battery part forms a jellyroll shape by stacking and winding a first electrode, a second electrode, and a separator interposed between these two electrodes. The first and second electrode tabs are coupled to the first and second electrodes, respectively, and are drawn out in the same direction. A protective member is positioned between the first and second electrode tabs and the front flange portion, respectively, to insulate the electrode tab and the front flange portion, and to improve adhesion between the electrode tab and the front flange portion. The battery unit is accommodated in the pouch case, and the flange portion extended to the outside of the storage space is heat-sealed and sealed. At this time, a portion of the first and second electrode tabs is sealed to be exposed to the outside of the front flange portion.

However, in the pouch type secondary battery having the above structure, the electrode assembly may flow in the case during external shock such as battery drop. As a result, the coupling force between the battery unit and the electrode tab may be weakened, thereby increasing the internal resistance IR of the battery, or the electrode tab may flow to loosen the sealing of the front flange of the pouch case.

In addition, there is a problem in that the battery portion inside the case is concentrated to the lower case when the battery falls, the impact of the battery is increased.

The present invention is to solve this problem, by fixing the electrode assembly to the battery case using a fixing member, to prevent the flow of the electrode assembly in the case during the external shock, such as battery dropping to ensure the stability of the battery have.

A secondary battery according to an aspect of the present invention for achieving this object,

An electrode assembly including two different electrodes and a battery unit in which separators interposed between the two electrodes are stacked and wound, and electrode tabs respectively drawn from the two electrodes; A case having an accommodating space for accommodating the electrode assembly and having a sealing part sealed at an outer side of the accommodating space; And a fixing member attached to the battery part and sandwiched between the sealing parts when sealing the sealing part.

In this case, the fixing member may fix the winding end of the battery unit.

In addition, at least a portion of the fixing member sandwiched between the sealing portions is preferably made of a heat resistant material.

On the other hand, the secondary battery according to another aspect of the present invention for achieving the above object,

An electrode assembly including two different electrodes and a battery unit in which separators interposed between the two electrodes are stacked and wound, and electrode tabs respectively drawn from the two electrodes; A case having an accommodating space for accommodating the electrode assembly and having a sealing part sealed at an outer side of the accommodating space; And one side is attached to the surface of the battery unit, the other side is characterized in that it comprises a fixing member attached to the inner surface of the case.

In this case, the fixing member may fix the winding end of the battery unit.

Hereinafter, with reference to the accompanying drawings will be described in detail an embodiment of a secondary battery according to the present invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

1 is an exploded perspective view of a pouch type secondary battery according to an exemplary embodiment of the present invention.

Referring to the drawings, the pouch type secondary battery includes an electrode assembly 30 including a battery unit 40, electrode tabs 52 and 56, and protective members 62 and 66, and a housing of the electrode assembly 30. It comprises a pouch case, a fixing member 70 for fixing the battery unit 40 and the pouch case.

The battery unit 40 generally forms the first electrode 42 and the second electrode 46 in a wide plate shape in order to increase the capacitance, and then separates the separator 44 from the first electrode 42 and the first electrode 42. It is laminated between two electrodes 46 and wound in a spiral shape to form a so-called 'Jelly Roll'. The second electrode 46 and the first electrode 42 may be formed by coating carbon as the second electrode active material and lithium cobalt acid as the first electrode active material, respectively, on a current collector made of copper and aluminum foil. The separator 44 is made of polyethylene, polypropylene, or a copolymer of polyethylene and polypropylene. Separator 44 is formed to be wider than the first electrode 42 and the second electrode 44, it is advantageous to prevent the short circuit between the electrode plates.

In order to electrically connect the first electrode 42 and the second electrode 46 of the battery unit 40 to the outside of the pouch case, one side of the first electrode 42 and the second electrode 46 may be respectively provided with a first electrode and a second electrode. Two electrode tabs 52 and 56 are formed. The electrode tabs 52 and 56 are ultrasonically welded and fixed to a non-coated portion, which is a portion of each electrode plate, to which an active material is not applied, and is generally formed of aluminum, copper, or nickel. These electrode tabs 52 and 56 are formed to protrude from the jelly roll in the direction perpendicular to the direction in which the jelly roll is wound, and are drawn out through the pouch through the front flange portion 23, which is a side of the pouch case sealed.

The insulating first and second protective members 62 and 66 are positioned between the front flange 23 of the pouch case and the first and second electrode tabs 52 and 56, respectively. That is, the protective members 62 and 66 surround the first and second electrode tabs 52 and 56, respectively. As the protective members 62 and 66, a polypropylene resin having a melting point of about 180 ° C. may be used so as to have excellent insulation and not to withstand and remove heat applied in the pouch sealing operation. Even if the polymer film on the inner side of the pouch is damaged, the protective members 62 and 66 can prevent the electrode tabs 52 and 56 from directly contacting the aluminum foil of the pouch. In addition, the protective members 62 and 66 surrounding the electrode tabs 52 and 56 serve to cushion the pressure difference between where the electrode tab is and where it is not, thereby improving the sealing state.

The pouch case has a lower case 20 in which an accommodating space 21 is provided through press processing and the like so that the electrode assembly 30 can be seated, and an upper portion formed integrally connected from one end of the lower case 20. The case 10 is provided. The pouch case has a form in which the polymer film 13 is laminated inside and outside the metal foil 11 such as an aluminum thin plate. Modified polypropylene, such as polymer resin, such as CPP (Casted Polypropylene), is applied to the thin aluminum sheet to form a heat-adhesive layer, and a resin material such as nylon or polyethylene terephthalate (PET) is formed on the outer surface thereof. At the edge of the lower case 20, front and side flange portions 23 and 25 extending in the front and both sides in the storage space 21 are formed to be bonded to the upper case 10 to seal the pouch case. have. However, the content of the present invention is not necessarily limited thereto.

The upper case which houses the electrode assembly 30 in the pouch case and contacts the flange portions 23. 25 of the three surfaces of the lower case 20 while the electrode tabs 52 and 56 are exposed to the outside of the pouch case ( 10) is heated and pressurized to form three-sided sealing portions. However, the content of the present invention is not limited to the pouch shape described above, and may be applied to a method of accommodating the electrode assembly in a pouch case having an open surface and sealing the one surface.

At least a part of the fixing member 70 has an adhesive layer formed thereon, which is attached to the upper surface of the battery unit 40, and the fixing member 70 has a portion outside the area of the battery unit 40 when viewed from above. Attached to (40), the deviation is sandwiched between the sealing portions during sealing of the sealing portions.

Here, at least part of the fixing member 70, which is sandwiched between the sealing parts, is heat-sealed together at the time of sealing the sealing part.

Therefore, by fixing the battery unit 40 to the electrode assembly 30 to the battery case using the fixing member 70, it is possible to secure the stability of the battery by preventing the flow of the electrode assembly in the case during the external shock such as battery drop Will be.

2A and 2B illustrate a first embodiment of the present invention, in which a part of the fixing member 70 is fitted between the front flange portion 23 and the upper case (not shown) of the lower case 20. have. In addition, as shown, it may be sandwiched between the protective member 62, 66 and the front flange portion 23, the upper case.

3 is a view showing a second embodiment of the present invention, wherein a part of the fixing member 70 'is fitted between the side flange portion 25 of the lower case 20 and the upper case (not shown).

4 is a view showing a third embodiment of the present invention, wherein a part of the fixing member 70 "is disposed between the front flange portion 23 and the upper case (not shown) of the lower case 20, and the lower case 20. As shown in FIG. It is fitted between the side flange portion 25 and the upper case.

Furthermore, in the first to third embodiments described above, the fixing members 70, 70 ', 70 "serve as a finishing tape for fixing the winding end (marked with a vertical dotted line in each drawing) of the battery unit 40. In other words, in order to prevent loosening of the wound battery unit 40, a finishing tape attached to the winding end of the battery unit 40 is formed larger than the battery unit 40 so as to remove a portion away from the battery unit region. By sealing between the sealing parts during sealing, the effect according to the invention can be achieved.

In addition, in the above-described first to third embodiments, one surface of the fixing members 70, 70 ', 70 "is attached to the surface of the battery unit 40, and the other surface is attached to the inner surface of the case (for example, the upper case). In this case, the coupling force between the case and the battery unit 40 is increased, thereby greatly reducing the flow of the battery unit in the case during external impact.

Meanwhile, FIG. 5 is a view showing a fourth embodiment of the present invention. Referring to the drawings, an electrode assembly having a battery part and an electrode tab is accommodated in a pouch case. One surface of the fixing member 170 is a battery part. It is attached to the surface of 40, and the other surface is attached to the inner surface of a case. As the fixing member 170, a double-sided adhesive tape may be used.

Even in this case, the bonding force between the case and the battery unit 40 is increased to greatly reduce the flow of the battery unit in the case at the time of external shock, thereby improving the stability of the battery.

In addition, the fixing member 170 may also play a role of fixing the winding end of the battery unit 40, the content described in the above embodiments may be equally applied.

In the secondary battery according to the present invention, the electrode assembly is fixed to the battery case by using a fixing member, thereby preventing the flow of the electrode assembly in the case during external shock such as battery drop, thereby ensuring the stability of the battery.

Although the present invention has been described with reference to the illustrated embodiments, it is merely exemplary, and the present invention may encompass various modifications and equivalent other embodiments that can be made by those skilled in the art. Will understand.

Claims (10)

An electrode assembly including two different electrodes and a battery unit in which separators interposed between the two electrodes are stacked and wound, and electrode tabs respectively drawn from the two electrodes; A case having an accommodating space for accommodating the electrode assembly and having a sealing part sealed at an outer side of the accommodating space; And A fixing member attached to the battery part and sandwiched between the sealing parts when sealing the sealing part, The case includes a lower case having a storage space for accommodating the electrode assembly and having a front flange portion and a side flange portion extending to the front and both sides of the storage space, and integrally connected to a rear end of the lower case. An upper case joined to the front and side flange parts to form the sealing part, A portion of the fixing member is located between the front flange portion of the lower case and the upper case, and another portion of the fixing member is located between the side flange portion of the lower case and the upper case. Secondary battery. The method of claim 1, The fixing member is a secondary battery, characterized in that for fixing the winding end of the battery unit. delete delete delete The method of claim 1, A part of the fixing member is a secondary battery, characterized in that located between the front flange portion and the upper case of the lower case, and between the side flange portion and the upper case of the lower case. The method according to any one of claims 1, 2 and 6, Part of the fixing member sandwiched between at least the sealing portion is a secondary battery, characterized in that made of a heat-resistant material. The method according to any one of claims 1, 2 and 6, One side of the fixing member is attached to the surface of the battery unit, the other side is a secondary battery, characterized in that attached to the inner surface of the case. An electrode assembly including two different electrodes and a battery unit in which separators interposed between the two electrodes are stacked and wound, and electrode tabs respectively drawn from the two electrodes; A case having an accommodating space for accommodating the electrode assembly and having a sealing part sealed at an outer side of the accommodating space; And One side is attached to the surface of the battery unit, the other side includes a fixing member attached to the inner surface of the case, The case includes a lower case having a storage space for accommodating the electrode assembly and having a front flange portion and a side flange portion extending to the front and both sides of the storage space, and integrally connected to a rear end of the lower case. An upper case joined to the front and side flange parts to form the sealing part, A portion of the fixing member is located between the front flange portion of the lower case and the upper case, and another portion of the fixing member is located between the side flange portion of the lower case and the upper case. Secondary battery. The method of claim 9, The fixing member is a secondary battery, characterized in that for fixing the winding end of the battery unit.

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