WO2014088332A1

WO2014088332A1 - Taped electrode assembly, and electrochemical device comprising same

Info

Publication number: WO2014088332A1
Application number: PCT/KR2013/011189
Authority: WO
Inventors: 권태현; 이관수; 류덕현
Original assignee: 주식회사 엘지화학
Priority date: 2012-12-07
Filing date: 2013-12-05
Publication date: 2014-06-12

Abstract

The present invention relates to an electrode assembly in which a separation membrane is prevented from being pressed and/or disconnected when free edge electrodes are wound into a jelly roll. The present invention also relates to an electrochemical device comprising the electrode assembly.

Description

Tape-treated electrode assembly and electrochemical device comprising the same

The present invention relates to a tape-treated electrode assembly and an electrochemical device including the same, and more particularly, to press and / or disconnection of a separator generated in a separator when winding in a jelly roll form using a free edge electrode. It relates to an electrode assembly and an electrochemical device including the electrode assembly to prevent the phenomenon.

This application claims the priority based on Korean Patent Application No. 10-2012-0142021, filed December 7, 2012 and Korean Patent Application No. 10-2012-0142030, filed December 7, 2012, All content disclosed in the specification and drawings of an application is incorporated in this application.

In addition, the present application claims priority based on Korean Patent Application No. 10-2013-0150012 filed December 4, 2013, all the contents disclosed in the specification and drawings of the application is incorporated in this application.

Recently, interest in energy storage technology among electrochemical devices is increasing. As the field of application extends to the energy of mobile phones, camcorders and laptops, and even electric vehicles, efforts for research and development of batteries are increasingly being realized. The electrochemical device is the most attracting field in this respect, and among them, the development of a secondary battery capable of charging and discharging has become a focus of attention.

Looking at an embodiment of the electrode used in the conventional secondary battery with reference to Figure 1, the electrode active material layer (2, 2 ') is coated on both sides of the current collector 3 of the elongated sheet form, the current collector At the end of (3), there is an embodiment of the electrode 1 to which the electrode active material layers 2 and 2 'are coated so that the active material non-coating portion a without the electrode active material layers 2 and 2' is formed.

After the electrode is stacked on the separator to form the electrode assembly, the electrode end, more precisely, the end of the electrode winding portion may be pressed to the separator when the electrode is wound in the form of a jelly roll. In the electrode having a), the phenomenon in which the disconnection of the separator may be prevented by reducing or reducing the membrane stress by reducing or reducing the phenomenon in which the end portion of the electrode winding is terminated by the portion of the active material non-coating portion (a) is pressed or reduced. There is an advantage.

However, when the electrode 1 having the active material non-coating portion (a) is used, the active material slurry is scattered on the active material non-coating portion of the current collector when the electrode active material, particularly the positive electrode active material, is coated to form an active material island. In addition, the island has been pointed out as a cause of the internal short circuit of the battery when the current collector sheet is drawn by repeated shrinkage and expansion of the jelly roll in a high capacity model life test.

Accordingly, as shown in FIG. 2, a free egde electrode 1 manufactured by applying the electrode

active material layers

2 and 2 ′ to both surfaces of the current collector 3 and cutting the active material uncoated portion does not exist is proposed. .

As used herein, the term 'free edge electrode' is understood to mean an electrode in which an active material layer and a current collector both form ends at the same position.

However, the free egde electrode shown in FIG. 2 does not have a problem in that islands are formed due to scattering of active materials, whereas the electrode active material layer and the current collector form ends at the same position, thereby forming a high density step. ) Is laminated on the separator 5 and the stress that the separator 5 receives from the end of the electrode at the end of the winding when the coil is wound in the jelly roll form is the stress that is received when the coil is wound in the jelly roll form using the electrode having the active material non-coated portion. It was much larger than that, resulting in more pressing and / or disconnection problems in the separator.

In one embodiment of the present invention to provide an electrode assembly including a free edge electrode and wound in the form of jelly roll, the crushing and / or disconnection phenomenon of the separator is alleviated or prevented.

In addition, another embodiment of the present invention is to provide an electrochemical device including the electrode assembly.

In addition, another embodiment of the present invention is to provide a method for manufacturing the electrode assembly in a more simplified method.

According to one embodiment of the present invention, in an electrode assembly including an electrode in which an electrode active material layer and a current collector form a step at the same position, an electrode assembly having an insulating tape interposed between an electrode end and a separator is provided. .

The insulating tape may have a width substantially the same as the electrode width.

The electrode end may be an end positioned at the winding end when the electrode assembly is wound in a jelly-roll form.

The electrode can be an anode, a cathode or both an anode and a cathode.

In the electrode assembly, the insulating tape may be laminated by being bonded to the separator, and the electrodes may be stacked so that the electrode end is placed on the insulating tape.

An insulating tape or an elastic material may be further attached to the electrode end that is in the electrode winding end portion of the electrode end and does not face the separator.

The elastic material may be styrene-butadiene rubber.

Two insulating tapes are used in the electrode assembly, one of the insulating tapes is attached to the lower surface of the electrode, another insulating tape is attached to the upper surface of the electrode, and the insulating tape is perpendicular to the lower surface of the electrode and the upper surface of the electrode, respectively. It may be attached in close contact with the electrode thickness direction end.

One insulating tape may be used in the electrode assembly, and the insulating tape may be continuously attached to an electrode thickness direction end portion and an upper surface perpendicular to the lower surface of the electrode.

According to another embodiment of the present invention, there is provided a method of manufacturing an electrode assembly comprising the step of laminating an insulating tape on the separator, and laminating the electrode so that the end of the electrode winding end portion on the insulating tape.

The method may further include applying an insulating tape or an elastic material slurry to an electrode end which is in the electrode winding termination end of the electrode end and does not face the separator.

According to another aspect of the invention, the step of attaching an insulating tape to each of the upper and lower surfaces of the electrode end; Attaching the insulating tape to an electrode thickness direction end portion perpendicular to each of the upper and lower surfaces of the electrode end; And it provides a method for producing an electrode assembly comprising the step of laminating the electrode on the separator.

According to another aspect of the invention, there is provided an electrochemical device comprising the above-described electrode assembly in the form of a jelly roll.

The electrochemical device may be a lithium secondary battery.

According to one embodiment of the present invention, an insulating tape is interposed between the electrode end of the portion where the electrode winding is terminated and the separator, thereby reducing or preventing the separator from being pressed and / or disconnected.

In addition, according to another embodiment of the present invention, there is a process advantage that the insulating tape can be applied to the electrode by a more simplified process.

1 is a cross-sectional view schematically showing one embodiment in which an electrode on which an active material non-coating portion is formed is laminated on a separator.

2 is a schematic cross-sectional view of an embodiment in which free edge electrodes are stacked on a separator.

3 is a cross-sectional view illustrating an embodiment of the present invention in which an insulating tape is stacked on a separator, and free edge electrodes are stacked on the separator and the insulating tape.

4 is a top view of FIG. 3 from above.

5 is an insulating tape is stacked on the separator, free edge electrodes are stacked on the separator and the insulating tape, the elastic material is applied to the end of the free edge electrode at the end of the winding and do not face the separator in the free edge electrode A cross-sectional view showing one embodiment of the present invention.

6A is a cross-sectional view schematically illustrating an example in which an insulating tape is attached to each of an upper end surface and an lower end surface of a portion where the winding of the free edge electrode is terminated.

FIG. 6B is a schematic cross-sectional view of an insulating tape attached to an upper surface of an electrode and a lower surface of the electrode of FIG. 6A, and attached to an end portion of an electrode thickness direction perpendicular to each of the upper and lower surfaces of the electrode.

FIG. 6C is a cross-sectional view schematically illustrating an insulating tape-treated free edge electrode of FIG. 6B stacked on a separator. FIG.

FIG. 7 is a top view of FIG. 6C seen from above.

8 is a cross-sectional view schematically illustrating an example in which an insulating tape center part is bent and attached to an electrode.

Hereinafter, the present invention will be described in detail. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the configuration described in the drawings described herein is only one of the most preferred embodiment of the present invention and does not represent all of the technical idea of the present invention, various equivalents and modifications that can replace them at the time of the present application It should be understood that there may be examples.

In one embodiment of the present invention there is provided an electrode assembly with an insulating tape interposed between the free edge electrode and the separator. Particularly, the electrode end is preferably an end portion of the winding end portion in which the separator is most stressed due to the free edge electrode when the electrode assembly is wound in a jellyroll form.

In order to describe the present invention in more detail, an embodiment of the present invention will be described with reference to FIG. 3.

Referring to FIG. 3, an insulating tape 4 is stacked on the separator 5, and an electrode 1 is stacked on the insulating tape 4 and the separator 5. In particular, the ends of the electrodes must be laminated on the insulating tape 4.

The electrode 1 may include the current collector 3 and the active material layers 2 and 2 'formed on at least one surface of the current collector 3, and the current collector 3 and the active material layer ( 2 and 2 'correspond to the free edge electrode 1 forming an end portion at the same position.

As can be seen from FIG. 4, the width W4 of the insulating tape is preferably equal to or slightly larger than the electrode width W1 in order to achieve the object of the present invention of preventing the separator from being pressed and / or disconnected. "Identical" in the present invention includes the error range of the level acceptable in the art.

The material of the insulating tape is not particularly limited as long as it has insulating properties and is not reactive to the electrolyte solution. Non-limiting examples of insulating tape materials satisfying these characteristics include polyethylene, polypropylene, polyester, nylon, vinyl chloride, Teflon®, polyimide, kapton®, polyphenylene sulfide, and the like. Can be. The insulating tape may also be elastic. When the elastic insulating tape is used, the lifting phenomenon between the electrode and the separator can be reduced because the insulating tape is interposed between the electrode and the separator.

The insulating tape is not particularly limited as long as it meets the object of the present invention in terms of thickness. That is, while the insulating tape can mitigate / prevent the membrane crushing and / or disconnection phenomenon, it should not unnecessarily increase the battery volume. In particular, the electrode assembly of the present invention is wound in the form of a jelly roll is stored in a battery can, and a liquid electrolyte is injected therein to be manufactured as an electrochemical device, so that the close contact between the separator and the electrode for the electrolyte transfer between the separator and the electrode It doesn't cost. In one embodiment of the present invention, the thickness of the insulating tape may be 10 to 20 μm.

Referring to FIG. 3, the length of the insulating tape 4a between which the insulating tape 4 is interposed between the electrode 1 and the separator 5 and the length of the insulating tape exposed on the separator 5 are 4b. As long as it meets the objective of this invention, it will not specifically limit. For example, in one embodiment of the present invention, the length 4a of the insulating tape interposed between the electrode and the separator may be 5 to 20 mm, and the length 4b of the insulating tape exposed on the separator 5 is It may be 5 to 10 mm.

The insulating tape 4 may have an adhesive layer formed on one surface thereof. At this time, the insulating tape 4 is laminated on the separator 5 so that the adhesive layer is attached to the separator 5. The adhesive material applicable to the insulating tape is not particularly limited as long as it can dissolve in the electrolyte and impart a predetermined adhesive force between the electrode and the separator. Alternatively, the insulating tape may be adhered to the separator by thermal fusion.

An electrode can mean an anode, a cathode, or both an anode and a cathode. Therefore, the above embodiment may include both an embodiment in which the insulating tape is interposed between the anode and the separator, an embodiment interposed between the negative electrode and the separator, and an embodiment interposed between the positive electrode and the separator and also between the negative electrode and the separator.

The active material constituting the electrode is not particularly limited in the present invention.

The separator usable in the present invention can be used without particular limitation in the separator commonly used in the art, for example, a porous polymer separator, a composite separator formed on at least one surface of the porous polymer substrate, engineering plastic separator, etc. Can be. In this case, the term "porous polymer substrate" means a substrate formed of a material commonly used as a separator material in the art, such as a polyolefin-based compound, and is understood to include both a film substrate and a nonwoven substrate. In addition, the term “porous coating layer” includes a mixture of inorganic particles and a binder polymer, and the inorganic particles are filled in contact with each other to be bound to each other by the binder polymer, thereby interstitial between the inorganic particles. Interstitial volumes are formed, and interstitial volumes between the inorganic particles become empty spaces to form pores.

In addition, referring to FIG. 5, in another embodiment of the present invention, in addition to the insulating tape 4 interposed between the electrode 1 and the separator 5, the free edge electrode end that is not facing the separator and is at the end of the winding. Additional insulating tape or elastic material 6 may be further applied.

The insulating tape 6 may be an insulating tape of the same material as or different from the insulating tape 4 interposed between the electrode 1 and the separator 5. As the elastic material 6, an elastic and non-conductive material such as styrene-butadiene rubber may be used.

The time point at which the insulating tape or elastic material 6 is applied to the electrode is not particularly limited, and for example, at any time before the electrode 1 is laminated on the separator 5 or the electrode 1 is separated from the separator 5. Can be applied at any time after lamination to

When the insulating tape 6 is applied to the electrode, the adhesive surface of the insulating tape may be attached to the upper surface of the electrode and the portion perpendicular to the upper surface of the electrode.

If an elastic material, such as a styrene-butadiene rubber slurry, is applied to the electrode, a subsequent process of applying the slurry to the electrode and then drying may be further needed.

Another embodiment of the present invention is shown in FIGS. 6A-6C.

Referring to FIG. 6A, two insulating tapes 4 ′ and 4 ″ are prepared, and adhesive surfaces of the insulating tapes 4 ′ and 4 ″ are attached to the upper and lower surfaces of the electrode 1. The two insulating tapes 4 ′ and 4 ″ may have the same length.

Next, referring to FIG. 6B, each of the insulating tapes 4 ′ and 4 ″ is closely attached to an electrode thickness direction end surface perpendicular to the upper electrode surface and an electrode thickness direction end surface perpendicular to the lower surface of the electrode. If there is an excess of insulating tape after the attachment, the tail as shown in FIG. 6B is formed. The tail may help alleviate the compression / break of the separator.

Subsequently, as shown in FIG. 6C, electrodes 1 with insulating tapes 4 ′ and 4 ″ are stacked on the separator 5.

Since the process of manufacturing the above embodiment consists of attaching two insulating tapes 4 'and 4 " to the upper and lower surfaces of the electrode end, and to adhere closely to the electrode thickness direction end, the process is simple. It has the advantage of being simple. This process is a very advantageous process advantage, given the complex facility and process needed to bend the insulating tape center in the embodiment of FIG. 8 described below. In addition, according to the process according to Figs. 6A to 6C, there is also an advantage that the insulating tape can be attached to the electrode more closely.

The material, thickness, width, and adhesive material of the insulating tape used in FIGS. 6A to 6C are the same as those of the embodiments of FIGS. 3 to 5, and therefore, reference is made to those described with reference to FIGS. 3 to 5. do.

The length of the insulating tape attached to the upper and lower surfaces of the electrode is also not particularly limited as long as it does not meet the object of the present invention. In one embodiment of the present invention, the length of the insulating tape attached to the upper or lower surface of the electrode may be 5 to 20 μm, and the length of the tail may be 5 to 10 μm.

Another embodiment of the invention is shown in FIG. 8.

Referring to FIG. 8, the center portion of one sheet of insulating tape 4 is prepared to bend, and the electrode free edge is manufactured through the process of attaching to the insulating tape 4.

The electrode treated with the insulating tape prepared in FIG. 8 also has the effect of alleviating or preventing the separation and / or disconnection of the separator when winding in the form of a jelly roll. However, in the present embodiment, as described above, a facility for bending the central portion of the insulating tape 4 is required, and the end portion in the thickness direction in which the insulating tape 4 having a curvature is perpendicular to the upper and upper surfaces of the electrode is provided. Care should be taken to ensure tight attachment to the and bottom surfaces.

The electrode assembly prepared as described above may be manufactured and used as an electrochemical device by injecting an electrolyte after being wound in a jelly roll form and stored in a battery can, and the electrochemical device usable in the present invention will be described below.

The positive electrode active material and the negative electrode active material usable in the present invention, and also the positive electrode current collector and the negative electrode current collector may be used without particular limitation as long as they can be commonly used in the art.

As the cathode active material, a lithium-containing transition metal oxide or a lithium chalcogenide compound may be used, and representative examples thereof may be LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , or LiNi _1-xy Co _x M Metal oxides such as _y O ₂ (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1, and M may be Al, Sr, Mg, La, etc.) may be used, but are not limited thereto. no.

As the negative electrode active material, a carbon material such as crystalline carbon, amorphous carbon, carbon composite, carbon fiber, lithium metal, lithium alloy, or the like may be used, but is not limited thereto.

As the positive electrode current collector, those obtained by surface treatment of carbon, nickel, titanium, silver on the surface of stainless steel, nickel, aluminum, titanium or alloys thereof, aluminum or stainless steel, and the like can be used.

As a negative electrode current collector, the thing which surface-treated carbon, nickel, titanium, silver on the surface of stainless steel, nickel, copper, titanium or their alloy, copper, or stainless steel can be used.

Electrolyte that may be used in one embodiment of the present invention is A ⁺ B ^- A salt of the structure, such as, A ⁺ comprises a Li ^+, Na ^+, an alkali metal cation or an ion composed of a combination thereof, such as K ⁺ B ^- it is _{^{_{^{PF 6 -, BF 4 -,}}}} Cl -, Br -, I -, ClO 4 -, AsF 6 -, CH 3 CO 2 -, CF 3 SO 3 -, N (CF 3 SO 2) 2 -, C Salts containing ions consisting of anions such as (CF ₂ SO ₂ ) ₃ ^- or a combination thereof are propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl Carbonate (DPC), dimethylsulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethylmethylcarbonate (EMC), gamma-butyrolactone or Some dissolved or dissociated in an organic solvent composed of a mixture thereof, but are not limited thereto.

The electrolyte injection may be performed at an appropriate stage of the battery manufacturing process, depending on the manufacturing process and the required physical properties of the final product. That is, it may be applied before the battery assembly or at the end of battery assembly.

Claims

An electrode assembly comprising an electrode in which an electrode active material layer and a current collector form ends at the same position,

An electrode assembly having an insulating tape interposed between an electrode end and a separator.
The method of claim 1,

And the insulating tape has a width equal to an electrode width.
The method of claim 1,

The electrode end is an electrode assembly, characterized in that the end is located at the end of the winding when the electrode assembly in the form of a jelly-roll (jelly-roll).
The method of claim 1,

And the electrode is an anode, a cathode or both an anode and a cathode.
The method of claim 1,

The insulating tape is bonded to the separator and laminated;

The electrode assembly, characterized in that the electrode is laminated so that the electrode end on the insulating tape.
The method of claim 5,

An electrode assembly, characterized in that an insulating tape or elastic material is further attached to an electrode end which is in the end portion of the electrode winding and which does not face the separator.
The method of claim 6,

Electrode assembly, characterized in that the elastic material is styrene-butadiene rubber.
The method of claim 1,

Two insulation tapes are used,

One of the insulating tapes is attached to the lower surface of the electrode,

Another insulating tape is attached to the top of the electrode,

And the insulating tape is closely attached to an electrode thickness direction end portion perpendicular to the lower surface of the electrode and the upper surface of the electrode.
The method of claim 1,

One insulation tape is used,

And the insulating tape is continuously attached to an electrode thickness direction end portion and an upper surface perpendicular to the lower surface of the electrode.
Laminating an insulating tape on the separator, and

Stacking electrodes so that the ends of electrode winding terminations are placed on the insulating tape;

The manufacturing method of the electrode assembly of Claim 4.
The method of claim 10,

The electrode assembly manufacturing method of the electrode assembly further comprising the step of applying an insulating tape or elastic slurry to the electrode end that is in the end portion of the electrode winding is not facing the separator.
Attaching insulating tape to each of the top and bottom surfaces of the electrode end;

Attaching the insulating tape to a thicknesswise end perpendicular to each of the top and bottom surfaces of the electrode end; And

Stacking the electrodes on a separator;

The manufacturing method of the electrode assembly of Claim 8.
An electrochemical device comprising the electrode assembly of any one of claims 1 to 9 in the form of a jelly roll.
The method of claim 13,

Electrochemical device, characterized in that the electrochemical device is a lithium secondary battery.