KR100601555B1 - Jelly-roll type electrode assembly and Li Secondary battery with the same - Google Patents

Abstract

The present invention relates to a wound electrode assembly having improved thermal stability and a secondary battery having the same. The present invention provides a positive electrode active material layer coated with a positive electrode active material on a positive electrode current collector, and a positive electrode having positive electrode uncoated portions at both ends of the positive electrode current collector. An electrode plate; A negative electrode active material layer coated with a negative electrode active material on a negative electrode current collector, and a negative electrode electrode plate including negative end portions of both ends of the negative electrode current collector; A separator interposed between the positive electrode plate and the negative electrode plate to insulate them; It is characterized by providing a wound electrode assembly comprising a separator fixing tape attached to at least one of the uncoated portion of both ends of the positive electrode plate or the negative electrode plate.

Secondary Battery, Electrode Assembly, Separator, Fixing Tape

Description

Winding electrode assembly and lithium secondary battery using same {Jelly-roll type electrode assembly and Li Secondary battery with the same}

1 is an exploded perspective view for explaining a lithium secondary battery according to an embodiment of the present invention.

2A to 2E are views illustrating a state before winding of an electrode assembly of a lithium secondary battery according to an embodiment of the present invention, and FIG. 2F is a view of winding of an electrode assembly of a lithium secondary battery according to an embodiment of the present invention. Figure showing the state.

3 is a cross-sectional view illustrating a separator fixing tape used in a lithium secondary battery according to an embodiment of the present invention.

(Explanation of symbols for main parts of drawing)

100; Secondary battery 110; Secondary Battery Case

200; Electrode assembly 210; Anode electrode plate

211; Positive electrode current collector 212; Positive electrode active material layer

213; Anode flat portion 215; Anode tab

220; Cathode electrode plate 221; Negative electrode current collector

222; Negative electrode active material layer 223; Negative electrode

225; Negative electrode tab 230; Separator

240; Insulating tapes 250, 255; Separator fixing tape

251; Base substrate 252; Adhesive layer

300; Cap assembly 310; Cap plate

311; Terminal through 312; Electrolyte injection hole

315; Bowl 320; Terminal electrode

330; Gasket 340; Insulation Plate

350; Terminal plate 360; Insulated case

362; Electrolyte injection through hole

The present invention relates to a wound electrode assembly and a secondary battery having the same, and more particularly, to a wound electrode assembly having improved thermal stability and a secondary battery having the same.

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 a battery pack that can be operated 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 rechargeable 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 increasing in terms of high energy density per unit weight. to be.

Such lithium secondary batteries mainly use lithium-based oxides as positive electrode active materials and carbon materials as negative electrode active materials. In general, a battery is classified into a liquid electrolyte battery and a polymer electrolyte battery according to the type of electrolyte, and 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. Moreover, although a lithium secondary battery is manufactured in various shapes, typical shapes include cylindrical shape, square shape, and pouch type.

Typically, the lithium secondary battery is positioned between the positive electrode plate coated with a positive electrode active material, the negative electrode plate coated with a negative electrode active material, and between the positive electrode plate and the negative electrode plate to prevent a short and prevent lithium ion (Li-ion). And an electrode assembly in which a separator capable of moving only is wound, a lithium secondary battery case accommodating the electrode assembly, and an electrolyte solution injected into the lithium secondary battery case to enable movement of lithium ions.

The lithium secondary battery is coated with the positive electrode active material and the positive electrode tab is connected to the positive electrode tab, the negative electrode active material is coated, the negative electrode plate is connected to the negative electrode tab and the separator is laminated, and then wound to prepare an electrode assembly.

Then, the electrode assembly is accommodated in the lithium secondary battery case to prevent the electrode assembly from being separated, an electrolyte is injected into the lithium secondary battery case, and then sealed to complete the lithium secondary battery.

However, in the lithium secondary battery as described above, when overcharging occurs during charging, the temperature inside the electrode assembly is increased, and this increase in temperature may cause deformation of the electrode assembly. In particular, when the temperature inside the electrode assembly rises, the separator is thermally contracted, and the thermal contraction of the separator may cause a short between the positive electrode plate and the negative electrode plate of the electrode assembly. That is, there is a problem in that the thermal stability of the electrode assembly and the lithium secondary battery is degraded during the overcharge.

An object of the present invention is to solve the above problems of the prior art, the present invention is to provide a wound electrode assembly and a secondary battery having the improved thermal stability using a separate fixing tape.

The present invention for achieving the above object is a positive electrode active material layer coated with a positive electrode active material on the positive electrode current collector, a positive electrode electrode plate having a positive electrode non-coating portion of both ends of the positive electrode current collector; A negative electrode active material layer coated with a negative electrode active material on a negative electrode current collector, and a negative electrode electrode plate including negative end portions of both ends of the negative electrode current collector; A separator interposed between the positive electrode plate and the negative electrode plate to insulate them; It is characterized by providing a wound electrode assembly comprising a separator fixing tape attached to at least one of the uncoated portion of both ends of the positive electrode plate or the negative electrode plate.

The present invention also provides a wound electrode assembly having a separator fixing tape attached to at least one of the uncoated portions of both ends of the positive electrode plate or the negative electrode plate; A case surrounding the electrode assembly; It is characterized in that it provides a lithium secondary battery comprising a cap assembly is coupled to the case and sealed and the terminal portion is electrically connected to the electrode assembly.

It is preferable that the separator fixing tape is attached to two uncoated portions at both ends of one of the positive electrode plate and the negative electrode plate.

The separator fixing tape may be formed of any one of the plain portions at both ends of the electrode plate of the positive electrode plate and the negative electrode plate, and at least one of the plain portions at both ends of the other electrode plate. It is preferable that it is attached to the plain part on the opposite side to the plain part to which the separator fixing tape of a board was attached.

It is preferable that the separator fixing tape is attached to both the plain portions at both ends of the positive electrode plate and the negative electrode plate.

The separator fixing tape includes a base film; It is preferable that it consists of an adhesive bond layer apply | coated on the upper and lower surfaces of the said base substrate.

It is preferable that the base substrate is made of a material having a deformation temperature of 150 ° C. or more, and more preferably, the base substrate is made of any one of polypropylene, polyimide, and polypropylene sulfide.

It is preferable that the adhesive layer does not react with the electrolyte solution, and is made of a material having adhesion. More preferably, the adhesive layer is acryl.

It may further include a separator fixing tape attached to surround the bottom of the outermost surface of the electrode assembly. A lithium secondary battery, characterized in that.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

1 is an exploded perspective view for explaining a lithium secondary battery according to an embodiment of the present invention.

Referring to FIG. 1, a lithium secondary battery 100 according to an exemplary embodiment of the present invention may include a secondary battery case 110, a jelly-roll electrode assembly 200 accommodated in the secondary battery case 110, and a lithium secondary battery 100. The cap assembly 300 is coupled to the upper portion of the secondary battery case 110.

The secondary battery case 110 is made of a metal material having a substantially rectangular shape, and may itself serve as a terminal.

The electrode assembly 200 includes a positive electrode plate 210 having a positive electrode tab 215, a negative electrode plate 220 having a negative electrode tab 225, and a positive electrode plate 210 and a negative electrode plate 220. The separator 230 interposed therebetween is configured to be wound. At the boundary portion where the positive electrode tab 215 and the negative electrode tab 225 are drawn out from the electrode assembly 200, an insulating tape 240 may be used to prevent a short circuit between the positive electrode plate 210 and the negative electrode plate 220. Each is insulated.

The cap assembly 300 is provided with a flat cap plate 310 having a size and shape corresponding to the opening of the secondary battery case 110. A terminal through hole 311 is formed at the center of the cap plate 310, and an electrolyte injection hole 312 for injecting an electrolyte is formed at one side of the cap plate 310, and the electrolyte injection hole 312 is formed. ) Is combined with the bowl 315 and sealed.

An electrode terminal 320, for example, a negative electrode terminal, may be inserted into the terminal through hole 311. The outer surface of the electrode terminal 320 is provided with a tube-shaped gasket 330 for electrical insulation with the cap plate 310. An insulation plate 340 is disposed on the bottom surface of the cap plate 310. The terminal plate 350 is installed on the bottom surface of the insulating plate 340.

The electrode terminal 320 is inserted through the terminal through hole 311 while the gasket 330 surrounds the outer circumferential surface. The bottom portion of the electrode terminal 320 is electrically connected to the terminal plate 350 in a state of interposing the insulating plate 340.

A positive electrode tab 215 drawn from the positive electrode plate 210 is welded to a lower surface of the cap plate 310, and a negative electrode tab drawn from the negative electrode plate 220 is attached to a lower end of the electrode terminal 320. 225 is welded.

On the other hand, the upper surface of the electrode assembly 200 electrically insulates the electrode assembly 200 and the cap assembly 300, and at the same time an insulating case 360 that can cover the upper end of the electrode assembly 200 Is installed. The insulating case 360 is provided with an electrolyte injection hole 362 at a position corresponding to the electrolyte injection hole 312 of the cap plate 310, so that the electrolyte can be injected. The insulating case 360 is an insulating polymer resin, preferably made of polypropylene, but the material is not limited in the embodiment of the present invention.

2A to 2E illustrate a state before winding of an electrode assembly of a lithium secondary battery according to an exemplary embodiment of the present invention.

Figure 2f illustrates a state after the winding of the electrode assembly of the lithium secondary battery according to an embodiment of the present invention.

2A to 2F, the electrode assembly 200 of the lithium secondary battery 100 according to the exemplary embodiment of the present invention includes a cathode electrode plate 210, an anode electrode plate 220, and a separator 230, respectively. It consists of a strip (strip), and arranged in the order of the positive electrode plate 210, the separator 230, the negative electrode plate 220, the separator 230, wound in a jelly-roll type (jelly-roll type) The separator 230 is fixed by the separator fixing tape 250 attached to the positive electrode plate 210 and the negative electrode plate 220.

Alternatively, although not shown in the drawing, each of the positive electrode plate 210 and the negative electrode plate 220 is formed of a single strip, and the electrode of any one of the positive electrode plate 210 and the negative electrode plate 220. The plate is wound in a jelly-roll shape in a state in which the separator 230 is wrapped, and the separator 230 is a separator fixing tape 240 attached to the positive electrode plate 210 and the negative electrode plate 220. It is fixed by.

The cathode electrode plate 210 includes a cathode current collector 211 made of a thin metal plate having excellent conductivity, for example, aluminum (Al) foil, and a cathode active material layer 212 coated on both surfaces thereof. have. As a cathode active material, a chalcogenide compound is used. For example, complex metal oxides such as LiCoO 2, LiMn 2 O 4, LiNiO 2, LiNi 1-x Cox O 2 (0 <x <1), and LiMnO 2 are used. It is not intended to limit. Both ends of the positive electrode plate 210 may be a region of the positive electrode current collector 211 where the positive electrode active material layer 212 is not formed, that is, the positive electrode non-coating portion 213, and either one of the positive electrode non-coating portions 213. The positive electrode tab 215 is electrically connected to each other.

The negative electrode plate 220 includes a negative electrode current collector 221 made of a conductive metal plate, for example, copper (Cu) or nickel (Ni) foil, and a negative electrode active material layer 222 coated on both surfaces thereof. have. As the negative electrode active material, a carbon (C) -based material, Si, Sn, tin oxide, tin alloy composites, transition metal oxide, lithium metal nitride, or lithium metal oxide is used, but the material is limited in the present embodiment. It is not. Both ends of the negative electrode plate 220 may be an area of the negative electrode current collector 221 in which the negative electrode active material layer 222 is not formed, that is, the negative electrode non-coating portion 223, and any one of the negative electrode non-coating portions 223, For example, the negative electrode tab 225 is electrically connected to the negative electrode uncoated portion 223 opposite to the positive electrode tab 215 of the positive electrode plate 210.

The positive electrode plate 210 and the negative electrode plate 220, the positive electrode tab 215, and the negative electrode tab 225 may be disposed with different polarities, and the positive electrode tab 215 and the negative electrode tab 225 may be disposed. The boundary portion drawn out from the electrode assembly 200 is insulated with an insulating tape 240 to prevent a short circuit between the positive electrode plate 210 and the negative electrode plate 220.

The separator 230 prevents a short between the positive electrode plate 210 and the negative electrode plate 220 and enables only a charge of the lithium secondary battery 100, for example, movement of lithium ions. And, it is made of any one selected from the group consisting of polyethylene, polypropylene and a copolymer (co-polymer) of polyethylene and polyflopropylene, but the material is not limited in this embodiment. The separator 230 may be formed to be wider than the cathode electrode plate 210 and the cathode electrode plate 220 to prevent a short circuit between the anode electrode plate 210 and the cathode electrode plate 220.

In addition, the positive electrode active material layer 212 and the negative electrode active material layer 222 may be started after the positive electrode plate 210 and the negative electrode plate 220 are wound once. That is, the winding starts at the interface between the plain portions 213 and 223 and the cathode and anode active material layers 212 and 222.

As shown in FIGS. 2A to 2E, before the electrode assembly 200 is wound, the positive and negative electrode non-coating portions 213 and 223 of the positive electrode plate 210 or the negative electrode plate 220 may be provided. Separator fixing tape 250 to prevent deformation due to thermal contraction of the separator 230 by increasing the internal temperature of the lithium secondary battery 100 when overcharging occurs during charging of the lithium secondary battery 100. Is attached.

For example, as shown in FIG. 2A, the separator fixing tape 250 may be attached to only two negative electrode uncoated portions 223 at both ends of the negative electrode plate 220.

Alternatively, as shown in FIG. 2B, the separator fixing tape 250 may be attached only to two positive electrode uncoated portions 213 at both ends of the positive electrode plate 210.

Alternatively, as shown in FIGS. 2C and 2D, the separator fixing tape 250 may include any one of the positive electrode non-coating portions 213 at both ends of the positive electrode plate 210 and the both ends of the negative electrode plate 220. The negative electrode portion 223 may be attached only to the negative electrode portion 223 opposite to the portion 213 on which the separator fixing tape 250 is attached, among the portion 213 of the cathode electrode plate 210.

Alternatively, as shown in FIG. 2E, the separator fixing tape 250 may be attached to both the positive and negative electrode non-coating portions 213 and 223 at both ends of the positive and negative electrode plates 210 and 220.

In addition, as shown in FIG. 2F, a separator fixing tape 255 is further attached to the lower end of the outermost surface of the electrode assembly 200 after being wound, thereby preventing the separator 230 from being deformed by thermal contraction. The deformation by thermal contraction of 230 is prevented.

3 is a cross-sectional view illustrating a separator fixing tape used in a lithium secondary battery according to an embodiment of the present invention.

Referring to FIG. 3, the separator fixing tape 250 attached to the electrode assembly 200 may have a substrate substrate having a deformation temperature higher than an internal temperature of the lithium secondary battery 100 during overcharging of the lithium secondary battery 100. 251, a base film, and an adhesive layer 252 applied on the upper and lower surfaces of the base substrate 251.

Since the internal temperature of the base substrate 251 is increased to about 150 ° C. during the overcharging of the lithium secondary battery 100, the base substrate 251 is preferably made of a material having a deformation temperature of about 150 ° C. or more, more preferably polypropylene. Any one of (Polyphenylene), polyimide (Polyimide) and polypropylene sulfide (Polyphenylene Sulfide, PPS) is used, but the type of the material is not limited in this embodiment.

The adhesive layer 252 does not react with the electrolyte solution of the lithium secondary battery 100, it is preferable to use a material having an adhesive force, more preferably it is preferable to use acrylic (acryl), this embodiment It is not intended to limit the type of material.

As described above, the separator fixing tape is attached to the positive electrode non-coating portion and the negative electrode non-coating portion, and the separator is fixed to prevent thermal shrinkage of the separator even when the internal temperature of the lithium secondary battery increases due to the overcharging of the lithium secondary battery. Thus, the short between the positive electrode plate and the negative electrode plate can be prevented. Therefore, the thermal stability of a lithium secondary battery can be improved.

As described above, according to the present invention, the present invention can provide a wound electrode assembly having a improved thermal stability and a secondary battery having the same by using a separator fixing tape.

While the foregoing has been described with reference to preferred embodiments of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. It will be appreciated.

Claims (13)

A positive electrode active material layer including a positive electrode active material layer coated with a positive electrode active material on a positive electrode current collector, and a positive electrode non-coating portion at both ends of the positive electrode current collector; A negative electrode active material layer coated with a negative electrode active material on a negative electrode current collector, and a negative electrode electrode plate including negative end portions of both ends of the negative electrode current collector; A separator interposed between the positive electrode plate and the negative electrode plate to insulate them; And a separator fixing tape having one surface attached to at least one non-coated portion of both ends of the cathode electrode plate or the cathode electrode plate, the other surface of which is attached to the separator to fix the separator. The method of claim 1, The separator fixing tape is attached to two uncoated portions of both ends of the electrode plate of the positive electrode plate and the negative electrode plate, characterized in that the wound electrode assembly. The method of claim 1, The separator fixing tape may be formed of any one of the plain portions at both ends of the electrode plate of the positive electrode plate and the negative electrode plate, and at least one of the plain portions at both ends of the other electrode plate. A wound electrode assembly, characterized in that it is attached to a plain portion opposite to the plain portion to which the separator fixing tape of the plate is attached. The method of claim 1, And the separator fixing tape is attached to both of the plain portions at both ends of the positive electrode plate and the negative electrode plate. The method of claim 1, The separator fixing tape A base film; A wound electrode assembly comprising an adhesive layer applied on upper and lower surfaces of the base substrate. The method of claim 5, The base substrate is a wound electrode assembly, characterized in that the deformation temperature is made of a material of 150 ℃ or more. A wound electrode assembly having one surface attached to at least one of the uncoated portions of both ends of the positive electrode plate or the negative electrode plate, the other surface being attached to the separator, and having a separator fixing tape for fixing the separator; A case surrounding the electrode assembly; And a cap assembly coupled with the case to seal the cap and having a terminal portion electrically connected to the electrode assembly. The method of claim 7, wherein The separator fixing tape A base film; A lithium secondary battery comprising an adhesive layer applied on upper and lower surfaces of the base substrate. The method of claim 8, The base substrate is a lithium secondary battery, characterized in that the deformation temperature is made of a material of 150 ℃ or more. The method of claim 8, The base substrate is a lithium secondary battery, characterized in that made of any one of polypropylene, polyimide and polypropylene sulfide. The method of claim 8, The adhesive layer does not react with the electrolyte, and the lithium secondary battery, characterized in that made of a material having an adhesive force. The method of claim 8, The adhesive layer is a lithium secondary battery, characterized in that acrylic. The method of claim 7, wherein And a separator fixing tape attached to surround the bottom of the outermost surface of the electrode assembly.

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