KR20060059698A - Lithum secondary battery having jelly-roll type electrode assembly - Google Patents

Abstract

The lithium secondary battery having the wound electrode assembly according to the present invention includes a first electrode plate coated with an electrode active material layer, a second electrode plate coated with an electrode active material layer having a different polarity from the first electrode plate, and a first electrode. Since the separator interposed between the plate and the second electrode plate to insulate the first electrode plate and the second electrode plate and the separator are laminated to maintain the wound state, and the fixing tape formed of a material that can transmit the electrolyte solution, The electrode assembly has an advantage in that the transmittance of the electrolyte or the ions is improved, thereby improving the performance of the secondary battery.

Secondary Battery, Electrode Assembly, Separator, Fixing Tape

Description

Lithium secondary battery having a wound electrode assembly {Lithum Secondary battery having Jelly-roll type electrode assembly}

1 is a perspective view showing an electrode assembly according to the present invention,

Figure 2 shows the separation of the electrode assembly according to the invention,

3 is a view showing an embodiment of a fixing tape according to the present invention,

Figure 4 shows another embodiment of a fixing tape according to the present invention,

5 is an exploded perspective view illustrating an embodiment of a lithium secondary battery to which an electrode assembly according to the present invention is applied.

<Brief Description of Major Codes in Drawings>

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

250; Fixing tape 251; Substrate

253; 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 lithium secondary battery having a wound electrode assembly, and more particularly to a lithium secondary battery having a wound electrode assembly having a fixing tape for closing the electrode assembly.

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 view of economical aspects, the battery pack employs a secondary 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 expanding 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.

In general, a lithium secondary battery used as a power source for a small electronic device is positioned between a positive electrode plate coated with a positive electrode active material, a 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 circuit. And a separator in which a separator capable of only movement of lithium ions (Li-ion) is wound, a lithium secondary battery case accommodating the electrode assembly, and an inside of the lithium secondary battery case are injected to enable movement of lithium ions. It consists of an electrolyte solution and the like.

The lithium secondary battery is coated with the positive electrode active material, the positive electrode electrode plate 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.

At this time, the electrode assembly is wound in the form of a jelly roll, and after attaching a fixing tape to surround the outer surface of the electrode jelly roll, it is formed by pressing the electrode jelly roll attached with the fixing tape.

However, since the conventional jelly roll type electrode assembly is wound and then attached to the fixing tape and then compressed, the electrode assembly accommodated in the case is kept in a hard state. Therefore, the electrolyte impregnation level during the electrolyte injection is lowered, the life characteristics of the electrode jelly roll may be worsened.

An object of the present invention is to solve the above problems of the prior art, the present invention is to provide a lithium secondary battery having a wound electrode assembly for raising the electrolyte impregnation level of the fixing tape for closing the electrode assembly. There is this.

The present invention for achieving the above object is a first electrode plate coated with an electrode active material layer, a second electrode plate coated with an electrode active material layer having a different polarity than the first electrode plate, and the first electrode plate And a separator interposed between the second electrode plate to insulate the second electrode plate and the electrode assembly to which the first electrode plate, the second electrode plate, and the separator are stacked, and the electrolyte is permeable. Provided is a lithium secondary battery having a wound electrode assembly comprising a tape.

The fixing tape is composed of a base film and an adhesive layer applied to the base substrate.

The base substrate may include a bottom cover part covering a bottom surface of the electrode assembly and a side cover part covering both side surfaces adjacent to a long side of the bottom surface.

It is preferable that the base substrate is formed of a material through which an electrolyte solution or ions can pass.

The base substrate may be formed of the same material as the separator.

The base substrate may be formed of a porous material, the porosity of the base substrate is preferably 1% or more.

The material of the base substrate may be made of any one of porous PE, porous PP, porous polyurethane, porous silica, PPS, PPA, PT.

The base substrate may be made of a material having a deformation temperature of 150 ° C. or more.

The base substrate may be formed in a mesh form.

It is preferable that the thickness of the said base substrate is 20 micrometers or less.

The adhesive layer does not react with the electrolyte solution, and may be acryl, and the adhesive layer may be applied only to the side cover part.

The thickness of the adhesive layer may be less than 35um.

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

1 is a perspective view showing an electrode assembly according to the present invention, Figure 2 is a view showing the separation of the electrode assembly according to the invention, Figure 3 is a view showing an embodiment of a fixing tape according to the present invention to be. Referring to these drawings, the lithium secondary battery is made of a jelly-roll-type electrode assembly 200 is received in the case 110, the electrolyte is injected and finished with a cap assembly 300.

The secondary battery case 110 is made of a metal material, and may itself serve as a terminal. Here, the case 110 may be formed in a cylindrical or square shape.

The electrode assembly 200 includes a first electrode plate 210 having a first electrode tab 215, a second electrode plate 220 having a second electrode tab 225, and the first electrode plate 210. ) And the separator 230 interposed between the second electrode plate 220 and the second electrode plate 220.

That is, in the electrode assembly 200, the first electrode plate 210, the second electrode plate 220, and the separator 230 each consist of one strip, and thus, the first electrode plate 210 and the separator 230. ), The second electrode plate 220 and the separator 230 are disposed in this order, and are wound in a jelly-roll type, and the separator 230 includes the first electrode plate 210 and the second electrode. The fixing tape 250 attached to the plate 220 is fixed.

Although not shown in the drawing, the electrode assembly 200 is formed of a strip of the first electrode plate 210 and the second electrode plate 220, respectively, the first electrode plate 210 and the second electrode plate 220. The electrode plate is wound in a jelly-roll shape in a state in which the separator 230 is wrapped around the separator plate 230, and the separator 230 is attached to the first electrode plate 210 and the second electrode plate 220. It may be fixed by the fixing tape 240.

The first electrode plate 210 may be an anode, and includes a first electrode current collector 211 made of a thin metal plate having excellent conductivity, for example, aluminum (Al) foil, and first coated on both surfaces thereof. The active material layer 212 is included. Chalcogenide compounds are used as the active material, and 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 in the present embodiment. It is not limited. Both ends of the first electrode plate 210 are regions of the first electrode current collector 211 where the first active material layer 212 is not formed, that is, the first electrode uncoated portion 213 and the first electrode uncoated portion ( The first electrode tab 215 is electrically connected to any one of the 213.

The second electrode plate 220 may be a cathode, a second electrode current collector 221 made of a conductive metal thin plate, for example, copper (Cu) or nickel (Ni) foil, and a second coated on both surfaces thereof. The active material layer 222 is included. The second active material may be a carbon (C) -based material, Si, Sn, tin oxide, composite tin alloys, transition metal oxides, lithium metal nitrides, or lithium metal oxides. It is not limited. Both ends of the second electrode plate 220 are regions of the second electrode current collector 221 where the second active material layer 222 is not formed, that is, the second electrode uncoated portion 223, and the second electrode uncoated portion 223. ), For example, the second electrode tab 225 is electrically connected to the second electrode uncoated portion 223 on the opposite side where the first electrode tab 215 of the first electrode plate 210 is formed. have.

The separator 230 prevents a short between the first electrode plate 210 and the second electrode plate 220 and allows only a charge of the lithium secondary battery 100 to move, for example, lithium ions. To do so, but 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 first electrode plate 210 and the second electrode plate 220 to prevent a short circuit between the first electrode plate 210 and the second electrode plate 220. .

In addition, the first active material layer 212 and the second active material layer 222 may be started after the first electrode plate 210 and the second electrode plate 220 are wound once. That is, the winding is started at the interface between the uncoated portions 213 and 223 and the first and second electrode active material layers 212 and 222.

Here, the wound electrode assembly 200 is attached with a fixing tape 250 to prevent the separator 230 or the first and second electrode plates 210 and 220 from being unwound in the wound state.

The fixing tape 250 may be attached to the lower end of the outermost surface of the electrode assembly 200 after being wound. That is, the bottom surface of the electrode assembly 200 and the long side portion adjacent to the long side portion of the electrode assembly 200 are attached to cover.

As a result, the fixing tape 250 may include a base substrate 251 having a deformation temperature higher than the internal temperature of the lithium secondary battery 100 when the secondary battery 100 is overcharged, and an image and a top of the base substrate 251. It consists of an adhesive layer 252 applied on the lower surface.

The base substrate 251 includes a bottom cover part 251a that covers the bottom of the wound electrode assembly 200, and a side cover part 251b that covers both side surfaces adjacent to the long side of the bottom of the electrode assembly 200.

Since the substrate temperature of the substrate 251 increases to about 150 ° C. when the lithium secondary battery 100 is overcharged, the deformation temperature is about 150 ° C. or more, and the thickness thereof is 20 μm or less. 200) thickness should be minimized.

On the other hand, since the substrate substrate 251 is formed of a material capable of transmitting electrolyte or ions, the substrate substrate 251 may be formed of the same material as the separator 230 that transmits electrolyte or ions. In addition, the substrate substrate 251 is preferably made of a porous material having a porosity of 1% or more so that the electrolyte solution or ions can permeate, more preferably porous PE, porous PP, porous polyurethane, porous silica, PPS, PPA, PT Any one of the materials may be used, but this embodiment does not limit the kind of the material.

In addition, as illustrated in FIG. 4, the substrate substrate 251 may be formed in a mesh type having a sieve shape having a predetermined interval and intersecting in a lattice shape. Therefore, the permeation of the electrolyte solution or the ions through the hole of the sieve is easy.

The adhesive layer 253 does not react with the electrolyte solution of the lithium secondary battery 100, and it is preferable to use a material having adhesion. More preferably, an acrylic is used, but in this embodiment It does not limit the kind of material. In addition, even if the adhesive layer 253 is applied only to the side cover portion 251b of the base substrate 251, the electrode assembly 200 may be fixed.

As described above, the wound electrode assembly 200 is closed by the cap assembly 300 as shown in FIG. 5 when it is accommodated in the rectangular case 110.

The cap assembly 300 is provided with a flat cap plate 310 having a size and a 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.

Therefore, the secondary battery assembled as described above is accommodated in the case 110, the electrode assembly 200 fixed with the fixing tape 250 formed of a material capable of transmitting electrolyte or ions is accommodated even if the temperature inside the secondary battery rises. The assembly is prevented from loosening.

As described above, according to the present invention, as the fixing tape of the wound electrode assembly is formed of a material such as a separator or a mesh type or porous material, the electrode assembly has an advantage of improving the permeability of the electrolyte or ions, thereby improving the performance of the secondary battery. There is this.

In addition, the wound electrode assembly attaches a fixing tape to fix the separator, thereby preventing thermal contraction of the separator even when the internal temperature of the lithium secondary battery increases due to overcharging of the lithium secondary battery, thereby preventing the cathode electrode plate and the cathode electrode. Short between plates can be prevented. Therefore, the thermal stability of a lithium secondary battery can be improved.

Although the above has been described with reference to the 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. I can understand that you can.

Claims (15)

A first electrode plate coated with an electrode active material layer; A second electrode plate coated with an electrode active material layer having a different polarity than the first electrode plate; A separator interposed between the first electrode plate and the second electrode plate to insulate them; And And a fixing tape formed of a material that maintains the wound state of the electrode assembly in which the first electrode plate, the second electrode plate, and the separator are stacked, and is capable of transmitting an electrolyte solution. The method of claim 1, The fixing tape is a base film; And Lithium secondary battery having a wound electrode assembly, characterized in that consisting of an adhesive layer applied to the base substrate. The method of claim 2, The base substrate includes a bottom cover part covering a bottom surface of the electrode assembly, and a side cover part covering both side surfaces adjacent to a long side of the bottom surface, the lithium secondary battery having a wound electrode assembly. The method of claim 3, wherein The base substrate is a lithium secondary battery having a wound electrode assembly, characterized in that formed of the same material as the separator. The method of claim 4, wherein The base substrate is a lithium secondary battery having a wound electrode assembly, characterized in that formed of a porous material. The method of claim 5, The porosity of the substrate substrate is a lithium secondary battery having a wound electrode assembly, characterized in that 1% or more. The method of claim 6, The material of the substrate is a lithium secondary battery having a wound electrode assembly, characterized in that made of any one of porous PE, porous PP, porous polyurethane, porous silica, PPS, PPA, PT. The method of claim 7, wherein The base substrate is a lithium secondary battery having a wound electrode assembly, characterized in that the deformation temperature is made of a material of 150 ℃ or more. The method of claim 4, wherein The base substrate is a lithium secondary battery having a wound electrode assembly, characterized in that formed in a mesh (mesh) form. The method of claim 4, wherein The thickness of the substrate substrate is a lithium secondary battery having a wound electrode assembly, characterized in that 20μm or less. The method of claim 2, The adhesive layer does not react with the electrolyte, the lithium secondary battery having a wound electrode assembly, characterized in that made of a material having an adhesive force. The method of claim 11, The adhesive layer is a lithium secondary battery having a wound electrode assembly, characterized in that the acrylic. The method of claim 3, wherein The adhesive layer is a lithium secondary battery having a wound electrode assembly, characterized in that applied only to the side cover. The method according to any one of claims 11 to 13, The thickness of the adhesive layer is a lithium secondary battery having a wound electrode assembly, characterized in that less than 35um. The method of claim 1, The first electrode plate is a lithium secondary battery having a wound electrode assembly, characterized in that the positive electrode plate.

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