KR20170051291A - Electrode Assembly Having Bonding Layer For Improving Hardness and Lithium Secondary Battery Comprising the Same - Google Patents

Abstract

The present invention comprises at least two electrodes, in which at least one surface of both surfaces is coated with an electrode active material, and a separation film interposed between the electrodes, wherein one surface or both surfaces of the separation film is/are coated with an adhesive layer containing an acrylic resin. Provided is an electrode assembly for a lithium secondary battery, in which the adhesive layer of the separation film is pressed on an electrode interface at the glass transition temperature (T_g) of the acrylic resin to form an electrode separation complex, in which the electrode and the separation film are coupled to each other.

Description

[0001] The present invention relates to an electrode assembly including an adhesive layer for improving hardness and a lithium secondary battery including the electrode assembly. [0002]

The present invention relates to an electrode assembly including an adhesive layer for improving hardness and a lithium secondary battery including the electrode assembly.

Due to the rapid increase in the use of fossil fuels, the demand for the use of alternative energy or clean energy is increasing. As a part of this, the most active field of research is electric power generation and storage.

At present, a typical example of an electrochemical device utilizing such electrochemical energy is a secondary battery, and the use area thereof is gradually increasing.

2. Description of the Related Art [0002] Recently, as technology development and demand for portable devices such as portable computers, portable phones, and cameras have increased, the demand for secondary batteries as energy sources has increased sharply. Among such secondary batteries, they exhibit high energy density and operating potential, Many studies have been made on a lithium secondary battery having a long self discharge rate, and it has been commercialized and widely used.

On the other hand, the stress caused by the expansion and contraction of the electrode during charging and discharging is accumulated in the electrode assembly, and when the stress accumulation exceeds the certain limit, deformation of the electrode assembly occurs, In order to prevent a gap from being generated between the electrode and the separator, a predetermined or higher adhesive force is required between the electrode and the separator, and a hardness of at least a predetermined level is required to prevent deformation of the electrode assembly.

In addition, a separation membrane of a polypropylene or polyethylene material may be used as a separation membrane of a lithium secondary battery in order to reduce the production cost. However, such a polymer separator has a disadvantage in that the separator may be broken due to an external impact in the manufacturing process of combining the separator and the electrode due to the disadvantage that the mechanical strength is weak.

Therefore, there is a high need for a technique capable of fundamentally solving such problems.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and the technical problems required from the past.

The inventors of the present application have conducted intensive research and various experiments and have found that the adhesive layer coated on one side or both sides of the separator is coated with an adhesive layer having a glass transition temperature T _g ) And the electrode and the separator are bonded to each other, the binding strength between the electrode and the separator is improved, the mechanical strength of the separator is improved, and the expansion and contraction of the electrode during charging and discharging It is possible to provide an electrode assembly for a lithium secondary battery that can effectively prevent deformation of an induced electrode assembly and thus can provide a battery with excellent stability and durability. The present invention has been accomplished based on this finding.

According to an aspect of the present invention, there is provided an electrode assembly for a lithium secondary battery,

Wherein the electrode active material is coated on at least one side of the both surfaces, and a separator interposed between the electrodes,

An adhesive layer including an acrylic resin is coated on one surface or both surfaces of the separator,

The adhesive layer of the separation membrane is characterized in that to form a membrane electrode conjugate, which is pressed against the electrode interface at the glass transition temperature (T _g) than the temperature of the acrylic resin and the electrode membrane is a binder with each other.

Here, when to press the bar is a part of the adhesive layer melt, melt adhesive as heating an adhesive layer coated on the membrane to the glass transition temperature (T _g) on the electrode interface, to exert the adhesive force between the electrode interface between the electrode and the membrane It may be such that the binding to each other, the curing of the molten adhesive at a temperature below the glass transition temperature (T _g) since it is possible to form a rigid high electrode membrane composite can have a higher strength than the hardness with a previous melt adhesive .

Thus, the lithium secondary battery, the electrode assembly according to the present invention, there is coated an adhesive layer containing an acrylic resin in the membrane one or both sides, is the adhesive layer is pressed against the electrode interface at a temperature between the glass transition temperature (T _g) or more acrylic resins By forming the electrode separation membrane composite in which the electrode and the separation membrane are bonded to each other, the binding force between the electrode and the separation membrane is improved and the mechanical strength of the separation membrane is improved, thereby effectively preventing deformation of the electrode assembly caused by expansion and contraction of the electrode during charging and discharging. The effect of improving the stability and durability of the battery is obtained.

In one specific example, the electrode assembly includes a stacked electrode assembly in which a positive electrode and a negative electrode are stacked in a height direction with respect to a plane with a separator interposed therebetween, or a stacked electrode assembly including a positive electrode, a negative electrode, A stack-folding type electrode assembly having a structure in which the unit cells are placed in a state of being placed, or a lamination-stacked electrode assembly in which unit cells are laminated and bonded in a height direction with respect to a plane.

In one specific example, the thickness of the adhesive layer may be determined according to how much the adhesive force between the electrode and the separator and the hardness of the electrode separator composite are set, and more specifically, may be 0.5 to 50 micrometers, Or from 0.5 micrometer to 1.0 micrometer, and more specifically from 1.0 micrometer to 20 micrometer. If the thickness of the adhesive layer is less than 0.5 micrometer, the adhesive strength and hardness required by the invention can not be exhibited. On the other hand, if the thickness is more than 50 micrometers, the ion conductivity may be deteriorated and the performance of the battery may deteriorate.

The adhesive layer may have a coating area of 50% to 100% of the total area of one surface of the separator. When the adhesive layer is less than 100%, the adhesive layer may be a pattern in which a plurality of strip shapes are repeatedly formed on a plane And can be coated with a pattern in which a plurality of island shapes are formed at equal intervals on a plane. The pattern coating of the adhesive layer has an area in which the adhesive layer exists between the separation membrane and the electrode and an area in which the adhesive layer is not present. In the non-existing area, the ion conductivity is not lowered, The adhesion between the electrode and the separator can be improved and the rigidity can be increased at the same time.

In one specific example, the pressing force by which the adhesive layer is pressed against the electrode interface may be from 580 kgf / m ² to 780 kgf / m ² , and more specifically from 640 kgf / m ² to 720 kgf / m < ² >, and more particularly 680 kgf / m < ² >. At this time, if the pressing force is less than 580 kgf / m ² , the adhesive layer may not exhibit the adhesion force and hardness between the electrode and the separator required by the present invention, and if it exceeds 780 kgf / m ² , Lt; / RTI >

In one specific example, the acrylic resin may have a glass transition temperature of 60 ° C. to 100 ° C., and a temperature higher than the glass transition temperature (T _g ) of the acrylic resin is 10 ° C. higher than T _g to T _g .

In one specific example, the acrylic resin contains at least one or more of a monomer, an oligomer, and a polymer having a low molecular weight, and a mixture of the monomer, oligomer, or low molecular weight polymer is polymerized to form an adhesive layer, (Meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate and the like, and the monomer or oligomer may be an acrylate or acrylic acid derivative. (Meth) acrylate, isobutyl acrylate, heptyl acrylate, isooctyl acrylate, 2-ethylhexyl (meth) acrylate, isodecyl acrylate, and lauryl Or more, and the polymer may be a polyester acrylate, an epoxy acrylate, It can be a urethane acrylate.

In one specific example, the adhesive layer may comprise an inorganic filler, and the content of the inorganic filler may be from 0.1% by weight to 30% by weight based on the total weight of the acrylic resin, and when the content exceeds 30% by weight , The adhesive strength of the adhesive layer may be lowered. On the other hand, when the content of the inorganic filler is 0.1% by weight or less, it is difficult to exhibit the effect of improving the hardness upon addition of the inorganic filler.

The inorganic filler may be selected from the group consisting of Al ₂ O ₃ , ZnO, ZnS, SiO ₂ , ZrO ₂ , SnO ₂ , CeO ₂ , MgO, CaO, Y ₂ O ₃ , TiO ₂ , Sb ₂ O ₃ , BaTiO ₃ , SrTiO ₃ , SiC, and Si ₃ N ₄ .

The average particle size (D50) of the filler may be 10 to 80% based on the thickness of the adhesive layer, and when the average particle size is less than 10%, the filler is formed with too small particles, If it exceeds 80%, it is possible to prevent the binding at the time of hot pressing of the adhesive layer on the electrode interface.

The present invention also provides a method of manufacturing the electrode assembly for a lithium secondary battery.

Specifically, a method of manufacturing an electrode assembly for a lithium secondary battery according to the present invention includes:

(a) forming an adhesive layer including an acrylic resin on one surface of the separator;

(b) arranging the electrodes so that the adhesive layer of the separator faces each other;

(c) pressing the adhesive layer of the separation membrane at a temperature higher than the glass transition temperature of the acrylic resin through a heat press process; And

(d) curing the bound electrode membrane composite at a temperature below the glass transition temperature;

. ≪ / RTI >

However, the present invention is not necessarily limited to the sequential steps (a) and (b), and the step (b) may be performed before the step (a) And can be included in the scope of the invention.

In one specific example, the acrylic resin may have a glass transition temperature of from 60 degrees centigrade to 100 degrees centigrade, and the pressing force at which the adhesive layer of the separator is pressed against the electrode interface in the step (c) is 580 kgf / m ² To 780 kgf / m < ² >.

In one specific example, the coating thickness of process (a) of the adhesive layer may be set to 190% to 210% of the thickness of the adhesive layer after the pressing process of process (c).

Further, in the above production method,

(e) forming an adhesive layer including an acrylic resin on a surface of the separator in which the adhesive layer of the step (d) is not coated;

(f) disposing an electrode having an opposite polarity to the electrode so as to face the adhesive layer of the separation membrane formed in the step (e);

(g) pressing the adhesive layer of the separation membrane at a temperature not lower than the glass transition temperature of the acrylic resin to an electrode interface having an opposite polarity through a heat press process; And

(h) curing the electrode separator composite bound in the step (g) at a temperature lower than the glass transition temperature;

As shown in FIG.

The present invention can also provide a battery cell including the electrode assembly for the lithium secondary battery.

Since the structure and manufacturing method of such a battery cell are well known in the art, detailed description thereof will be omitted herein.

The present invention also provides a battery pack including the battery cell.

Since the structure and manufacturing method of such a battery pack are well known in the art, a detailed description thereof will be omitted herein.

The present invention also provides a device including the battery pack as a power source. Specifically, the device may be, for example, a cellular phone, a portable computer, a wearable electronic device, a tablet PC, a smart pad, a netbook, a LEV (Light Electronic Vehicle), an electric vehicle, a hybrid electric vehicle, a plug- And a power storage device.

The structure and manufacturing method of such a device are well known in the art, so a detailed description thereof will be omitted herein.

As described above, the lithium secondary battery, the electrode assembly according to the invention, the separation membrane surface, or there is a bonding layer which on both sides comprises an acrylic resin is coated, the adhesive layer to the electrode at a temperature between the glass transition temperature (T _g) or more of an acrylic resin surface The electrode and the separator are bonded to each other to form an electrode separator composite. Thus, the adhesion between the electrode and the separator is improved, and the mechanical strength of the separator is improved. Thus, the deformation of the electrode assembly caused by the expansion and contraction of the electrode during charge- The present invention provides an electrode assembly for a lithium rechargeable battery, which is excellent in stability and durability of a battery.

1 is a schematic side view showing an electrode assembly for a lithium secondary battery according to an embodiment of the present invention;
2 is a schematic side view illustrating an electrode separation membrane composite of an electrode assembly for a lithium secondary battery according to an embodiment of the present invention;
FIG. 3 is a schematic side view showing a structure before thermocompression bonding of the electrode separation membrane composite according to one embodiment of the present invention; FIG.
4 is a schematic side view illustrating a structure in which an electrode separation membrane composite is formed on both sides of a separation membrane of an electrode assembly for a lithium secondary battery according to an embodiment of the present invention;
5 is a schematic side view illustrating an electrode separator composite of an electrode assembly for a lithium secondary battery according to another embodiment of the present invention;
6 is a flowchart illustrating a method of manufacturing an electrode assembly for a lithium secondary battery according to an embodiment of the present invention;
7 is a flowchart illustrating a method of manufacturing an electrode assembly for a lithium secondary battery according to another embodiment of the present invention;
8 is a graph showing the results of Experimental Example 1 of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited by the scope of the present invention.

FIG. 1 is a side view showing an electrode assembly for a lithium secondary battery according to an embodiment of the present invention. FIG. 2 is a cross-sectional view illustrating an electrode separator composite of an electrode assembly for a lithium secondary battery according to an embodiment of the present invention. The side view shown is schematically shown.

1, an electrode assembly 100 for a lithium secondary battery according to the present invention includes a positive electrode assembly 110 and a negative electrode assembly 124 coated on both sides of a current collector 112 with a current collector 122 A stacked electrode assembly 100 in which cathodes 120 coated on both sides are laminated in a height direction with respect to a plane with a separator 130 interposed therebetween.

Referring to FIG. 2, the electrode separator composite 200 of the electrode assembly 100 for a lithium secondary battery according to the present invention includes a positive electrode 110, a separator 130, and a lithium secondary battery electrode And an adhesive layer 140 including an acrylic resin coated on one side of the separation membrane 130 of the assembly 100. The adhesive layer 140 is pressed onto the interface of the anode 110 at a temperature not lower than the glass transition temperature T _g of the acrylic resin to form the electrode separation membrane composite 200 in which the anode 110 and the separation membrane 130 are bonded to each other have.

At this time, the thickness T ₁ of the adhesive layer 140 is 0.5 to 50 micrometers, and the total area of one surface of the separation layer 130 is 100%.

FIG. 3 schematically shows a side view showing a structure before thermocompression of an electrode membrane composite according to an embodiment of the present invention.

2 and 3, the coating thickness T ₃ of the adhesive layer 140 before the electrode separation membrane composite 200 is formed by thermocompression bonding is determined by the thickness T ₁ of the adhesive layer 140 after the pressing process, To 190% to 210%.

FIG. 4 is a schematic side view showing a structure in which an electrode separator composite 210 is formed on both sides of a separation membrane 130 of an electrode assembly for a lithium secondary battery according to an embodiment of the present invention.

4, an adhesive layer 141 including an acrylic resin is coated on one surface of the separation membrane 130 of the electrode separation membrane composite 210 in which the adhesive layer 140 is not formed, and the adhesive layer 141 ) has a glass transition temperature of the acrylic resin (T _g) is pressed on the electrode interface at temperatures above the cathode 120 and the separator 130 are electrode membrane composite (210 in the binder) is formed with one another.

FIG. 5 schematically shows a side view of an electrode separator composite 300 of an electrode assembly for a lithium secondary battery according to another embodiment of the present invention.

5, an electrode separator composite 300 of an electrode assembly (not shown) for a lithium secondary battery according to another embodiment of the present invention includes an inorganic filler 350 in an adhesive layer 340, Al ₂ O ₃ is used as the filler 230, and the content of the inorganic filler 350 is 0.1 wt% to 30 wt% with respect to the total weight of the acrylic resin.

The average particle diameter D50 of the inorganic filler 350 is 30% to 50% based on the thickness T ₁ of the adhesive layer 140.

6 is a flowchart illustrating a method of manufacturing an electrode assembly for a lithium secondary battery according to an embodiment of the present invention.

Referring to FIG. 6, a method 500 for manufacturing an electrode assembly for a lithium secondary battery according to the present invention includes:

(A) forming 510 an adhesive layer 140 including an acrylic resin on one surface of the separator 130;

(B) arranging the electrodes and the adhesive layer 140 of the separator 130 so as to face each other;

(C) a step (530) of pressing the adhesive layer 140 of the separation membrane 130 at a temperature higher than the glass transition temperature of the acrylic resin through the heat press process to the electrode interface; And

(D) curing (540) the cured electrode separator composite 200 at a temperature below the glass transition temperature;

.

Here, when to press the adhesive layer 140, a glass transition temperature (T _g) bar, which is a part of the adhesive layer 140 is melted, as heated to a melt adhesive layer 140 is coated on the membrane 130 to the electrode interface, The adhesive layer 140 is cured at a temperature lower than the glass transition temperature T _g and is cured to form the adhesive layer 140 before melting, And the rigidity of the electrode separator composite 200 is increased.

The glass transition temperature of the acrylic resin is from 60 degrees centigrade to 100 degrees centigrade. In step (c), the pressing force by which the adhesive layer 140 of the separation membrane 130 is pressed against the electrode interface is set to 580 kg · f / m ² to 780 kg · f / m ² .

The coating thickness of the adhesive layer 140 in step (a) 510 is set to 190% to 210% of the thickness of the adhesive layer 140 after the pressing process in step (c)

6 is a flowchart illustrating a method of manufacturing an electrode assembly for a lithium secondary battery according to another embodiment of the present invention.

Referring to Fig. 6, in the manufacturing method of Fig. 5,

(d) a step (e) of forming (610) an adhesive layer 140 including an acrylic resin on a surface of the separation membrane 130 of the process 540 where the adhesive layer 140 is not coated;

(F) step 620 of arranging the electrode having the opposite polarity to the electrode to face the adhesive layer 140 of the separation membrane 130 formed in the process (e);

(G) pressing (630) the adhesive layer (140) of the separation membrane (130) through a heat press process to an electrode interface having an opposite polarity at a temperature equal to or higher than the glass transition temperature of the acrylic resin; And

 (h) curing (640) the electrode separator composite 200 bound in step (g) at a temperature less than the glass transition temperature;

.

In the following Examples, Comparative Examples and Experimental Examples, the contents of the present invention will be described in more detail, but the present invention is not limited thereto.

≪ Example 1 >

(Preparation of electrode)

The slurry was prepared by mixing LiCoO ₂ (96 g), acetylene black (2 g) and PVDF binder (2 g) as active materials with NMP (N-methyl-2-pyrrolidone) Coated with a thickness of micrometer, dried and compressed to prepare a positive electrode.

(Preparation of electrode membrane composite)

The inorganic particle Al ₂ O ₃ is coated on one side of a polyethylene separator having a thickness of 7 μm and then an acrylic resin is applied to the adhesive layer to a thickness of 0.5 μm to prepare a coated separator. The one side of the prepared anode and the adhesive layer of the coated separator are arranged so as to face each other, and then they are pressed with a roller heated to 80 DEG C, which is a glass transition temperature, to bind the electrode and the separator.

Example 2 (Preparation of electrode separator composite)

Except that the acrylic resin was applied so that the thickness of the adhesive layer became 1.0 占 퐉.

≪ Comparative Example 1 > (Preparation of electrode separator composite)

Was prepared in accordance with the production method of Example 1, except that the acrylic resin was not applied.

≪ Comparative Example 2 > (Preparation of electrode separator composite)

Except that the acrylic resin was applied so that the thickness of the adhesive layer became 2.0 占 퐉.

≪ Experimental Example 1 > (Strength Measurement Test of Electrode Separator Composite)

The strength of the electrode membrane composite of Examples and Comparative Examples was measured using a Texture Analyzer (3pint bending) analyzer. The results are shown in FIG. 8 and Table 1 below.

Strength (Strength relative to Comparative Example 1,%) Comparative Example 1 100% Example 1 112% Example 2 138% Comparative Example 2 193%

As shown in Table 1, Examples 1 and 2 of the present invention showed higher strength than Comparative Example 1 in which no adhesive layer was formed, and the electrode assembly according to one embodiment of the present invention improved the mechanical strength of the separator, It can be expected that deformation of the electrode assembly caused by the expansion and contraction of the electrode during discharge can be effectively prevented. On the other hand, in Comparative Example 2, the strength is much higher than that in Examples 1 and 2, but the thickness of the adhesive layer is too thick, which is not suitable because the adhesive layer acts as a resistance against the charging and discharging performance of the battery.

As previously described, a lithium secondary battery, the electrode assembly according to the present invention, there is coated an adhesive layer containing an acrylic resin in the membrane one or both sides, wherein the adhesive layer is the electrode interface at a temperature between the glass transition temperature (T _g) or more acrylic resins By forming the electrode separation membrane composite in which the electrode and the separation membrane are pressed together, the binding force between the electrode and the separation membrane is improved and the mechanical strength of the separation membrane is improved. Thus, the deformation of the electrode assembly caused by the expansion and contraction of the electrode during charge / The present invention provides an electrode assembly for a lithium secondary battery which is excellent in stability and durability of a battery.

Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims (23)

Wherein the electrode active material is coated on at least one side of the both surfaces, and a separator interposed between the electrodes,
An adhesive layer including an acrylic resin is coated on one surface or both surfaces of the separator,
The adhesive layer of the membrane electrode assembly for a lithium secondary battery, characterized in that to form a membrane electrode conjugate, which is pressed against the electrode interface at the glass transition temperature (T _g) than the temperature of the acrylic resin and the electrode membrane is a binder with each other. The electrode assembly according to claim 1, wherein the electrode assembly includes a stacked electrode assembly in which an anode and a cathode are laminated in a height direction with respect to a plane with a separator interposed therebetween, or a stacked electrode assembly including an anode, a cathode, Stacked electrode assembly in which the unit cells are stacked in a height direction with respect to a plane, and stacked-stacked electrode assemblies having a structure in which the unit cells are wound in a state in which unit cells Assembly. The electrode assembly for a lithium secondary battery according to claim 1, wherein the thickness of the adhesive layer is 0.5 micrometers to 50 micrometers. The electrode assembly for a lithium secondary battery according to claim 3, wherein the thickness of the adhesive layer is 0.5 micrometer to 1.0 micrometer. The electrode assembly for a lithium secondary battery according to claim 1, wherein the coating area of the adhesive layer is 50% to 100% of the total area of one surface of the separator. The method according to claim 1, wherein the adhesive layer is coated with a pattern in which a plurality of strip shapes are repeatedly formed on a plane on a separation membrane, or a pattern in which a plurality of island shapes are formed at regular intervals on a plane Wherein the electrode assembly is a lithium secondary battery. The electrode assembly for a lithium secondary battery according to claim 1, wherein the pressing force by which the adhesive layer is pressed against the electrode interface is 580 kgf / m ² to 780 kgf / m ² . The electrode assembly for a lithium secondary battery according to claim 1, wherein the acrylic resin has a glass transition temperature of 60 ° C to 100 ° C. The electrode assembly for a lithium secondary battery according to claim 1, wherein the temperature of the glass transition temperature (T _g ) of the acrylic resin is 10 ° C higher than T _g to T _g . The acrylic resin according to claim 1, wherein the acrylic resin comprises at least one or more of a monomer, an oligomer and a low molecular weight polymer, and a mixture of the monomer, oligomer or low molecular weight polymer is polymerized to form an adhesive layer Wherein the electrode assembly is a lithium secondary battery. The electrode assembly for a lithium secondary battery according to claim 10, wherein the monomer or oligomer is an acrylate or acrylic acid derivative, and the polymer is a polyester acrylate, an epoxy acrylate, or a urethane acrylate. . The electrode assembly for a lithium secondary battery according to claim 1, wherein the adhesive layer comprises an inorganic filler. The electrode assembly for a lithium secondary battery according to claim 12, wherein the content of the inorganic filler is 0.1 wt% to 30 wt% with respect to the total weight of the acrylic resin. The method of claim 12, wherein the inorganic filler is selected from the group consisting of Al ₂ O ₃ , ZnO, ZnS, SiO ₂ , ZrO ₂ , SnO ₂ , CeO ₂ , MgO, CaO, Y ₂ O ₃ , TiO ₂ , Sb ₂ O ₃ , BaTiO ₃ a lithium secondary battery electrode assembly, characterized in that at least one selected from the group consisting of SrTiO _3, SiC and Si ₃ N _4. 13. The electrode assembly for a lithium secondary battery according to claim 12, wherein the average particle diameter (D50) of the filler is 10 to 80% based on the thickness of the adhesive layer. 16. A method of manufacturing an electrode assembly for a lithium secondary battery according to any one of claims 1 to 15,
(a) forming an adhesive layer including an acrylic resin on one surface of the separator;
(b) arranging the electrodes so that the adhesive layer of the separator faces each other;
(c) pressing the adhesive layer of the separation membrane at a temperature higher than the glass transition temperature of the acrylic resin through a heat press process; And
(d) curing the bound electrode membrane composite at a temperature below the glass transition temperature;
≪ / RTI > The method according to claim 16, wherein the acrylic resin has a glass transition temperature of 60 ° C to 100 ° C. The manufacturing method according to claim 16, wherein the pressing force by which the adhesive layer of the separator is pressed against the electrode interface in the step (c) is 580 kgf / m ² to 780 kgf / m ² . The method according to claim 16, wherein the coating thickness of the adhesive layer in step (a) is set to 190% to 210% of the thickness of the adhesive layer after the pressing step in step (c). 17. The method of claim 16,
(e) forming an adhesive layer including an acrylic resin on a surface of the separator in which the adhesive layer of the step (d) is not coated;
(f) disposing an electrode having an opposite polarity to the electrode so as to face the adhesive layer of the separation membrane formed in the step (e);
(g) pressing the adhesive layer of the separation membrane at a temperature not lower than the glass transition temperature of the acrylic resin to an electrode interface having an opposite polarity through a heat press process; And
(h) curing the electrode separator composite bound in the step (g) at a temperature lower than the glass transition temperature;
Further comprising the steps of: A battery cell comprising the electrode assembly for a lithium secondary battery according to any one of claims 1 to 15. A battery pack comprising the battery cell according to claim 21. A mobile device comprising the battery pack according to claim 22 as a power source.

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