KR102056734B1 - Adhesive of pouch type lithium secondary battery and the secondary battery prepared by using the same - Google Patents

Abstract

The present invention relates to an adhesive of a pouch-type lithium secondary battery and a secondary battery manufactured using the same. More particularly, the present invention relates to an adhesive composition disposed between an electrode assembly and a pouch in a pouch-type lithium ion secondary battery such that the electrode assembly is not separated from the pouch even when an external impact is applied, and a secondary battery manufactured using the same.

Description

Adhesive of Pouch-type Lithium Secondary Battery and Secondary Battery Manufactured Using the Same {ADHESIVE OF POUCH TYPE LITHIUM SECONDARY BATTERY AND THE SECONDARY BATTERY PREPARED BY USING THE SAME}

The present invention relates to an adhesive of a pouch-type lithium secondary battery and a secondary battery manufactured using the same. More particularly, the present invention relates to an adhesive composition disposed between an electrode assembly and a pouch in a pouch-type lithium ion secondary battery such that the electrode assembly is not separated from the pouch even when an external impact is applied, and a secondary battery manufactured using the same.

Since secondary batteries have electrical characteristics such as high energy density and excellent charge / discharge performance, demand for energy sources is increasing, and their application ranges are also diversified.

According to the shape of the battery case, the secondary battery may be classified into a cylindrical battery and a rectangular battery in which an electrode assembly is embedded in a cylindrical or rectangular metal can, and a pouch-type battery embedded in a pouch-type case.

In general, a lithium ion secondary battery wraps the outer surface of the electrode assembly with a tape to fix the electrode assembly (also referred to as a 'jelly roll') so that the electrode assembly is accommodated in a cylindrical or pouch type battery case. That is, the tape is attached to a state in which the positive electrode plate, the separator, and the negative electrode plate surround the outer surface of the electrode assembly stacked in this order. Generally, such a tape is called a finishing tape.

On the other hand, the pouch type lithium ion secondary battery (polymer battery) has an electrode assembly housed in a pouch-shaped battery case, and the electrode assembly flows in the pouch due to a drop or an external impact, thereby causing the electrode to be bent, causing a short, fire, explosion Will occur. Thus, in the related art, a finishing tape having a special function is used between the electrode assembly and the pouch so that the electrode assembly does not flow in the pouch even when the battery is impacted.

The pouch type secondary battery uses a finishing tape coated with an acrylic pressure sensitive adhesive (PSA) on a polypropylene (OPP) or polyethylene terephthalate (PET) film substrate as a finishing tape, and a PP coated surface of the pouch. And the PP or PET layer of the tape is pressed to face each other.

However, in the case of using the finishing tape as described above, the thickness is usually increased to 60 μm or more and is still detached from the adhesive surface in the drop test, causing the pouch and the electrode assembly to fall apart, causing various problems on the electrode. In addition, there is a problem that the energy density per volume is lowered as the thickness is increased.

An object of the present invention is to provide a secondary battery pouch adhesive composition that can increase the energy density by reducing the volume of the electrode assembly in the pouch in the pouch-type lithium ion secondary battery as well as preventing the phenomenon.

In addition, an object of the present invention is to provide a composition for a secondary battery pouch adhesive, which is normally in a state of no adhesive force and which makes it easy to store the electrode assembly separately prior to the step of being accommodated in the pouch.

Furthermore, an object of the present invention is to provide a composition for a secondary battery pouch adhesive having a significant stability compared to the existing adhesive tape in the impact resistance test and a lithium secondary battery manufactured using the same.

In order to achieve the above object, an aspect of the present invention

Adhesive composition for bonding the electrode assembly and the pouch of the secondary battery,

The adhesive composition relates to a pouch adhesive composition for a secondary battery including a polyolefin resin and an alkoxy silane compound modified with an ethylenically unsaturated carboxylic acid group or an ethylenically unsaturated carboxylate group.

In the adhesive composition for a secondary battery pouch according to an embodiment of the present invention, the alkoxy silane compound may be represented by the following formula (1).

[Formula 1]

(R ₁ ) _n Si (OR ₂ ) _4-n

(In Formula 1, R ₁ is a hydrocarbon group having at least one functional group selected from an epoxy group, an acryl group and an amino group, R ₂ is a straight or branched chain alkyl of 1 to 8 carbon atoms, n is 1 to 3 of Is an integer.)

In the adhesive composition for a secondary battery pouch according to an embodiment of the present invention, the alkoxy silane compound is 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4 -Epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, 3-glycidoxypropyl methyldiethoxysilane, 3-glycidoxypropyltriethoxysilane and It may be any one or more selected from 3-methacryloxypropyltrimethoxysilane.

In the adhesive composition for a secondary battery pouch according to the embodiment of the present invention, the alkoxy silane compound may be included in an amount of 0.1 to 20 parts by weight based on 100 parts by weight of the modified polyolefin resin.

In the adhesive composition for a secondary battery pouch according to the embodiment of the present invention, the polyolefin resin may include 0.1 to 10 mol% of an ethylenically unsaturated carboxylic acid group or an ethylenically unsaturated carboxylate group.

In the adhesive composition for a secondary battery pouch according to an embodiment of the present invention, the polyolefin resin is selected from the group consisting of polyethylene homopolymer, polypropylene homopolymer and copolymer of ethylene or propylene and C ₃ -C ₁₀ alphaolefin. It may be one or more.

In the adhesive composition for a secondary battery pouch according to the embodiment of the present invention, the modified polyolefin resin may have a weight average molecular weight of 15,000 to 300,000 g / mol.

Another aspect of the invention is laminated in the order of electrode assembly, adhesive layer and pouch, wherein the adhesive composition applies an adhesive composition comprising a polyolefin resin and an alkoxy silane compound modified with an ethylenically unsaturated carboxylic acid group or an ethylenically unsaturated carboxylate group. It relates to a lithium secondary battery which is then formed by thermal compression.

In the lithium secondary battery according to an embodiment of the present invention, the thermocompression may be performed under the conditions of 40 to 120 ℃, 1 to 10 atm.

In the lithium secondary battery according to an embodiment of the present invention, the adhesive layer may be a thickness of 1 to 20 ㎛.

In the lithium secondary battery according to an embodiment of the present invention, the adhesive layer may be an adhesive force of the battery assembly and the pouch when pressed at less than 100 ° C of 300 gf / in or more.

Another aspect of the invention

Coating on the electrode surface of the electrode assembly an adhesive composition for a secondary battery pouch comprising a polyolefin resin and an alkoxy silane compound modified with an ethylenically unsaturated carboxylic acid group or an ethylenically unsaturated carboxylate group,

Receiving the coated electrode assembly in a pouch;

Injecting an electrolyte into the pouch containing the electrode assembly;

Bonding the pouch and the electrode surface by thermal compression

It relates to a pouch-type lithium secondary battery manufacturing method comprising a.

In the method of manufacturing a lithium secondary battery according to an embodiment of the present invention, the coating of the adhesive composition may include bar coating, die coating, wire coating, comma coating, micro gravure coating, spray coating, dip coating, spin coating, It may be carried out by any one method selected from inkjet coating, roll coating and knife coating.

In the method of manufacturing a pouch-type lithium secondary battery according to an embodiment of the present invention, the thermal compression may be carried out under the conditions of 40 to 120 ℃, 1 to 10 atm.

The adhesive composition for a secondary battery pouch according to the present invention is coated with an adhesive layer, not an adhesive film form, between an electrode assembly and a pouch in a pouch-type lithium ion secondary battery, and has a low thickness and can further improve adhesive strength than a film. Even if an external shock such as a drop is applied to the electrode assembly, the electrode assembly is not separated from the pouch. In addition, it can significantly reduce the thickness than the adhesive film has the advantage of further increasing the energy density.

In addition, the adhesive composition for a secondary battery pouch according to the present invention is a process is carried out at a low temperature of the thermocompression bonding temperature of 80 ℃ or less, to ensure the process safety without the volume expansion of the electrolyte, and part of the electrolyte is vaporized Due to the bubble has an advantage that can prevent the rise of the internal pressure of the battery and thereby decrease the life of the battery.

In particular, the adhesive composition for the secondary battery pouch according to the present invention is coated on the surface of the electrode assembly and dried, the adhesive or adhesive properties on the surface completely disappear, coating the adhesive composition and drying the existing adhesive tape before the pouch into the pouch after drying In the case of attaching the tape to the pouch and the attached part, it is easy to stack and store it, because it can be stacked and stored. Has an advantage.

In addition, the pouch-type lithium secondary battery according to the present invention does not flow in the electrode assembly in the pouch during repeated drop of the battery, unlike the conventional battery, even if the battery is shocked, there is a possibility of short circuit, fire, explosion, etc. It has the advantage that it can be drastically reduced.

Hereinafter, an adhesive composition for a secondary battery pouch of the present invention and a secondary battery manufactured using the same will be described in detail. The invention can be better understood by the following examples. The following examples are for illustrative purposes of the invention and are not intended to limit the scope of protection defined by the appended claims. In this case, unless otherwise defined, the technical and scientific terms used have the meanings that are commonly understood by those of ordinary skill in the art.

The inventors of the present invention, while deepening the research on the technology that can stably fix the structure of the electrode assembly and the pouch by an external impact such as vibration, drop or continuous shaking in the pouch type secondary battery, ethylene-based carboxyl By forming an adhesive layer between the electrode assembly and the pouch using an adhesive composition comprising a polyolefin resin modified with an acid or a carboxylate and an alkoxy silane compound, the energy density per volume can be increased to a thickness thinner than that of a conventional adhesive tape. In the drop test, the present invention was found to have excellent impact resistance and at the same time improve workability.

Specifically, one aspect of the present invention is an adhesive composition for adhering the electrode assembly and the pouch of the secondary battery, wherein the adhesive composition comprises a polyolefin resin and an alkoxy silane compound modified with an ethylenically unsaturated carboxylic acid group or an ethylenically unsaturated carboxylate group. It is to provide a pouch adhesive composition for a secondary battery comprising.

The polyolefin resin is characterized by being modified with an ethylenically unsaturated carboxylic acid group or an ethylenically unsaturated carboxylic acid group. That is, the polyolefin resin is a modified polyolefin resin in which a monomer of ethylenically unsaturated carboxylic acid or ethylenically unsaturated carboxylate is grafted, and may improve adhesion to an electrode assembly and a pouch.

The monomer grafted to the modified polyolefin resin is specifically at least one selected from the group consisting of methacrylic acid, acrylic acid, maleic acid, fumaric acid and itaconic acid, an ethylenically unsaturated carboxylic acid and the ethylenically unsaturated carboxylic acid and a metal. Ethylenically unsaturated carboxylates including ionic salts, but are not necessarily limited thereto.

In this case, the polyolefin resin may be 0.1 to 10 mol%, specifically 0.5 to 6 mol%, more specifically 1 to 5 mol% of the ethylenically unsaturated carboxylic acid group or the ethylenically unsaturated carboxylic acid group based on the total number of moles. have. When the above range is satisfied, excellent adhesion can be realized even at a low thickness, and in particular, the adhesion performance between the electrode assembly and the pouch is excellent, and thus the impact resistance is improved.

The polyolefin resin may be any one or more selected from the group consisting of polyethylene homopolymer, polypropylene homopolymer and copolymer of ethylene or propylene and C ₃ -C ₁₀ alphaolefin, but is not limited thereto. Also, the polyolefin resin may be a chlorinated polyolefin, and specifically, may be chlorinated polypropylene. When using the chlorinated polyolefin resin may have excellent adhesion properties due to the high electronegativity of chlorine in the polypropylene-coated aluminum pouch inner material of the adherend.

The modified polyolefin resin may have a weight average molecular weight of 15,000 to 300,000 g / mol, preferably 20,000 to 200,000 g / mol. In addition, the modified polyolefin resin may have a melt index (190 ° C., 2.16 kg) of 0.2 to 20 g / 10 minutes, preferably 0.2 to 10 g / 10 minutes. In the case of satisfying the above range, the coating layer has excellent coating properties and excellent adhesion to the thickness and impact strength, but is not limited thereto.

According to one embodiment of the present invention, the adhesive composition is characterized in that it comprises an alkoxy silane compound at the same time as the modified polyolefin resin.

The alkoxy silane compound in combination with the modified polyolefin resin further strengthens the adhesive force with the electrode assembly and the pouch, in particular, excellent adhesion performance and impact strength against external shocks or repeated shocks and vibrations due to dropping in the battery. Has an effect that can be implemented.

The alkoxy silane compound may be represented by the following formula (1).

[Formula 1]

(R ₁ ) _n Si (OR ₂ ) _4-n

(In Formula 1, R ₁ is a hydrocarbon group having at least one functional group selected from an epoxy group, an acryl group and an amino group, R ₂ is a straight or branched chain alkyl of 1 to 8 carbon atoms, n is 1 to 3 of Is an integer.)

Specifically, the alkoxy silane compound is 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- ( 3,4-epoxycyclohexyl) ethyltriethoxysilane, 3-glycidoxypropyl methyldiethoxysilane, 3-glycidoxypropyltriethoxysilane and 3-methacryloxypropyltrimethoxysilane It may be one or more, but is not necessarily limited thereto. Preferably 3-methacryloxypropyl trimethoxysilane can be used.

The alkoxy silane compound may be included in an amount of 0.1 to 20 parts by weight, specifically, 0.5 to 15 parts by weight, based on 100 parts by weight of the modified polyolefin resin. It has a remarkable improvement effect, and since adhesiveness is not imparted to the dried adhesive layer, it has characteristics of easy storage and workability.

According to an embodiment of the present invention, in addition to the modified polyolefin resin, styrene-butadiene-styrene block copolymer (SBS), styrene-ethylene-butylene-styrene block copolymer (SEBS), acrylic resin, polyvinylidene fluoride Polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-co-trichloroethylene, polymethylmethacrylate, polyurethane, Polyacrylonitrile, polyvinylalcohol, polyvinylpyrrolidone, polyvinylacetate, ethylene vinyl acetate copolymer, polyimide , Polyethylene oxide, cellulose acetate, cellulose acetate butylate etate butyrate, cellulose acetate propionate, cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, It may further include any one or more components selected from the group consisting of pullulan (pullulan) and carboxyl methylcellulose (carboxyl methylcellulose). Preferably, the styrene-butadiene-styrene block copolymer and the styrene-ethylene-butylene-styrene block copolymer may be any one or more styrene-based elastomer resins, but is not limited thereto. It can give excellent elasticity and recovery of deformation and has the property of further improving not only the adhesive force but also the resistance due to impact resistance. At this time, the component can be adjusted in the content range within the range to achieve the desired physical properties in the present invention, preferably can be used in a 0.4 to 1.0 weight ratio, 0.6 to 0.8 weight ratio range compared to the modified polyolefin resin. When the above range is satisfied, the elasticity can be secured together with the adhesive performance and the synergistic effect of improving the impact resistance can be realized.

The modified polyolefin resin may be a content of 60 to 100% by weight, preferably 70 to 90% by weight of the solid content in the adhesive composition. In the case of satisfying the above range, despite the low thickness, excellent adhesion performance is achieved, as well as solvent resistance, in particular, electrolyte resistance, which is resistant to electrolytes, and has durability enhancing effects, but this is a non-limiting example and is limited to the above numerical range. Do not receive.

The modified polyolefin resin may preferably include 2 to 20 parts by weight, preferably 4 to 15 parts by weight, based on 100 parts by weight of the solvent contained in the adhesive composition. When the above range is satisfied, the coating property is excellent, and the adhesiveness, impact resistance, and solvent resistance have an effect of securing, but this is only one non-limiting example and is not limited to the numerical range.

The adhesive composition may include a solvent. The solvent may be used without limitation as long as it can impart the coating property of the adhesive composition, and specifically, may include any one or more selected from the group consisting of hydrocarbon-based, ester-based and ether-based solvents. More specifically, ethanol, isopropyl alcohol, toluene, cyclohexane, methylcyclohexane, ethylcyclohexane, trichloroethylene, 1,2-dichloroethylene, dichloromethane and n-propyl bromide, 1,1-dichloro-1- It may include any one or more selected from fluoroethane and propylene dichloride, but is not limited thereto.

The adhesive composition may further include additives commonly used in the art as needed in addition to the above-described configuration.

The adhesive composition for the secondary battery pouch of the present invention can further improve the energy density to volume due to the low thickness, and has an excellent adhesive performance to prevent the electrode assembly from flowing in the pouch in the pouch type secondary battery. Of course, excellent solvent resistance to the internal electrolyte, that is, electrolyte resistance can be achieved. Furthermore, it is dried in the absence of adhesive force during storage to facilitate storage of the electrode assembly, and also has excellent performance of re-expression of adhesive force due to thermocompression, and has no property deterioration in adhesion strength for long-term use and no structural deformation of the adhesive layer.

Another aspect of the invention is laminated in order of electrode assembly, adhesive layer and pouch,

The adhesive layer is a lithium secondary battery formed by applying an adhesive composition comprising a polyolefin resin and an alkoxy silane compound modified with an ethylenically unsaturated carboxylic acid group or an ethylenically unsaturated carboxylic acid group between the electrode assembly and the pouch and then thermocompression-bonded To provide.

The adhesive layer may have a thickness of 1 to 20 μm, specifically 5 to 15 μm. This can significantly reduce the thickness compared to the conventional adhesive tape. When the adhesive layer is used in the case of a conventional adhesive tape, the thickness thereof may be significantly lower than that of approximately 60 to 150 μm, and further, despite the low thickness, excellent adhesive performance may be realized, and in particular, the electrode assembly may be subjected to an impact test. The pouch has a synergistic effect on the adhesion and impact resistance that the pouch does not detach.

In one embodiment, the adhesive layer may be formed by applying an adhesive composition including a polyolefin resin modified with ethylenically unsaturated carboxylic acid or carboxylate to the surface of the electrode assembly or the surface of the pouch to form an adhesive composition layer between the electrode assembly and the pouch. It can be formed by forming and thermocompressing it.

At this time, the thermocompression process is carried out in a temperature range of 40 to 120 ℃, specifically 50 to 80 ℃, the pressure may be carried out under the conditions of 1 to 10 atm, specifically 2 to 8 atm, but is not necessarily limited thereto. no.

According to an aspect of the present invention, the adhesive layer is characterized in that the adhesion force of the battery assembly and the pouch at least 300 gf / in when pressed at less than 120 ℃, specifically, less than 80 ℃. When using a conventional adhesive tape, it compresses at a temperature above 100 ° C., generally at a temperature above 130 ° C. to impart adhesive force. The process at such a high temperature causes evaporation of a part of the electrolyte and bubbles inside the battery. As a result, the internal pressure may pressurize the jelly roll, thereby preventing the battery performance or reducing the battery life.

In addition, another aspect of the present invention comprises the steps of coating the above-described adhesive composition for a secondary battery pouch on the electrode surface of the electrode assembly,

Receiving the coated electrode assembly in a pouch;

Injecting an electrolyte into the pouch containing the electrode assembly;

Bonding the electrode surface of the pouch to the electrode assembly by thermal compression;

It provides a method of manufacturing a pouch-type lithium secondary battery comprising a.

The coating of the adhesive composition may be performed by coating the adhesive composition on the electrode surface of the electrode assembly, and the method of coating is not limited thereto, but may be bar coating, die coating, wire coating, comma coating, micro gravure coating, or spray coating. Any one method selected from among dip coating, spin coating, inkjet coating, roll coating and knife coating can be used.

According to an embodiment of the present invention, the electrode assembly coated with the adhesive composition is sufficiently dried to form an adhesive layer on the surface. At this time, the adhesive layer does not have an adhesive force, and before storing the electrode assembly in the pouch, the adhesive layer may be stored by stacking the electrode assembly formed on the surface separately, and the process efficiency may be prevented from being deteriorated due to sticking during operation. Excellent workability and workability. The adhesive layer is characterized in that the adhesive force is re-expressed by thermocompression in a later step.

After the electrode assembly coated with the adhesive composition is accommodated in a pouch, an electrolyte solution is introduced into the pouch in which the electrode assembly is accommodated. At this time, the adhesive composition has a solvent resistance to the electrolyte solution and has the property of no structural deformation of the adhesive layer.

After the electrolyte is introduced into the pouch containing the electrode assembly, the step of bonding the pouch and the electrode surface of the electrode assembly by thermocompression bonding.

At this time, the thermocompression process is carried out in a temperature range of 40 to 120 ℃, specifically 50 to 80 ℃, the pressure may be carried out under the conditions of 1 to 10 atm, specifically 2 to 8 atm, but is not necessarily limited thereto. no.

Hereinafter, an example of an adhesive of a pouch-type lithium secondary battery according to the present invention and a secondary battery manufactured using the same will be described. However, the present invention is not limited to the following examples.

(evaluation)

(1) adhesion

According to the same method as the adhesive layer formed according to the Examples and Comparative Examples to prepare a specimen (10cm × 10cm × 30mm) in accordance with KS M3734 and then to the specimen using a universal testing machine (TO-102 of TEST ONE) 10mm / Tensile shear strength was measured for the adhesive layer of the specimen while pulling at a speed of min and the results are shown in Table 1 below.

(2) Drop impact strength (drop test)

After manufacturing the secondary battery pouch-type jelly roll, each specimen was fixed to an aluminum pouch using adhesive and adhesive tape, put into a plastic case, and then assembled and sealed, at the height of 1m in the direction of 6 sides of the plastic case and 8 sides of each corner. Free fall was carried out, and this was defined as one time and the final number of falls satisfying the drop test is shown in Table 1 below.

(3) electrolyte resistance

In Examples and Comparative Examples, after forming an adhesive layer on the surface of the electrode assembly and then drying, 1M lithium salt (LiPF ₆ ) was added to the solvent (ethyl carbonate (EC) and ethyl methyl carbonate (EMC) in volume ratio (EC / EMC). ), Which is completely immersed in the electrolyte dissolved in 3/7 (v / v)) and left at 80 ° C. for 480 hours, and then checks if there is any structural deformation of the adhesive layer. When it peels, it described with x.

(4) adhesive

In Examples and Comparative Examples, the adhesive composition is sprayed onto the aluminum surface of the electrode assembly to form an adhesive layer, which is dried and then adhered to a 100 μm thick PE film on the adhesive layer to determine whether it is adhesive. In the case of adhesiveness, it is indicated by x.

(Example 1)

10 parts by weight of polypropylene having a weight average molecular weight of 63,000 g / mol and 1 part by weight of 3-methacryloxypropyltrimethoxysilane were dissolved in cyclohexane based on 100 parts by weight of cyclohexane, and then electrode. Fully sprayed on the aluminum surface of the assembly. Thereafter, after drying at 60 ° C. for 3 minutes, an electrode assembly coated with a thickness of 7 μm was prepared.

The electrode assembly on which the adhesive layer was formed was placed in an aluminum pouch coated with a PP film, and an electrolyte solution was added thereto. Next, adhesion was performed by pressing at 80 ° C. for 5 seconds at 5 atm.

(Example 2)

In Example 1, the same procedure as in Example 1 was carried out except that a polypropylene having a weight average molecular weight of 70,000 g / mol modified with 0.5 mol% of acrylic acid and 2.3 mol% of maleic acid was used.

(Example 3)

In Example 1, 8 parts by weight of polypropylene having a weight average molecular weight of 63,000 g / mol modified with 2.3 mole% of maleic acid, and 2 parts by weight of SEBS having a weight average molecular weight of 100,000 g / mol were further included. And the same method as in Example 1.

(Example 4)

In place of the modified polypropylene used in Example 1, was carried out in the same manner as in Example 1 except that maleic anhydride modified chlorinated polypropylene (Japan Paper, Superclone 822S) was used. It was.

(Example 5)

The same procedure as in Example 1 was carried out except that, in place of the modified polypropylene used in Example 1, a polypropylene having a weight average molecular weight of 75,000 g / mol modified with 11 mol% of maleic acid was used.

(Example 6)

Subsequent to the modification of the polypropylene used in Example 1, it was carried out in the same manner as in Example 1 except for using a polypropylene having a weight average molecular weight of 57,000g / mol modified with 0.05 mol% maleic acid.

(Comparative Example 1)

In Example 1, instead of forming an adhesive layer by spraying on the aluminum surface of the electrode assembly, it was carried out in the same manner as in Example 1 except that a commercially available product using an OPS double-sided adhesive tape having a thickness of 60㎛.

(Comparative Example 2)

Instead of using modified polypropylene, it was carried out in the same manner as in Example 1 except that bisphenol A epoxy resin (Kukdo Chemical, YD-020) was used.

TABLE 1

As can be seen in Table 1, the embodiments according to the present invention not only have a high adhesion between the electrode assembly and the pouch despite the very low thickness of the adhesive layer, the drop of the electrode assembly even in the drop test up to 25 times It was confirmed that the impact resistance could be improved significantly because no detachment occurred. In addition, it was confirmed that the solvent resistance is excellent, the adhesiveness is not expressed after drying, it is possible to laminate a large number of manufactured electrode assemblies to ensure easy storage and operation. On the other hand, Comparative Example 1 has a low adhesive strength to the thickness, the drop test was also only 6 times, it can be seen that the impact strength is significantly lower than the embodiment of the present invention. In addition, poor solvent resistance could not ensure electrode durability and safety due to the electrolyte. Comparative Example 2 also showed low adhesive strength and impact strength, poor solvent resistance, and could not secure storage and workability due to adhesive properties after drying.

As described above in the present invention has been described by a limited embodiment, which is provided only to help a more general understanding of the present invention, the present invention is not limited to the above embodiments, it is to be understood that the general knowledge in the field Those having a variety of modifications and variations are possible from these descriptions.

Therefore, the spirit of the present invention should not be limited to the described embodiments, and all the things that are equivalent to or equivalent to the claims as well as the following claims will belong to the scope of the present invention. .

Claims (9)

A pouch type lithium secondary battery in which an electrode assembly is inserted into a pouch,
An adhesive layer disposed between the pouch and the electrode assembly,
The adhesive layer is a pouch-type lithium secondary battery that is formed using an adhesive composition of a polyolefin resin modified with an ethylenically unsaturated carboxylic acid group or an ethylenically unsaturated carboxylic acid group and an alkoxy silane compound represented by the following formula (1).
[Formula 1]
(R ₁ ) _n Si (OR ₂ ) _4-n
(In Formula 1, R ₁ is a (meth) acryl group, R ₂ is a straight or branched chain alkyl of 1 to 8 carbon atoms, n is an integer of 1 to 3. delete The method of claim 1,
The alkoxy silane compound is a pouch-type lithium secondary battery containing 0.1 to 20 parts by weight based on 100 parts by weight of the modified polyolefin resin. The method of claim 1,
The polyolefin resin is a pouch type lithium secondary battery containing 0.1 to 10 mol% of an ethylenically unsaturated carboxylic acid group or an ethylenically unsaturated carboxylate group. The method of claim 1,
The polyolefin resin is any one or more selected from the group consisting of polyethylene homopolymer, polypropylene homopolymer and copolymer of ethylene or propylene and C ₃ -C ₁₀ alphaolefin. The method of claim 1,
The modified polyolefin resin has a weight average molecular weight of 15,000 to 300,000 g / mol pouch type lithium secondary battery. Forming an adhesive layer of any one of claims 1, 3 to 6 between the electrode assembly and the pouch,
Storing the electrode assembly in which the adhesive layer is formed in a pouch;
Injecting an electrolyte into the pouch containing the electrode assembly;
Thermally compressing the pouch and the electrode assembly
Method of manufacturing a pouch-type lithium secondary battery comprising a. The method of claim 7, wherein
The step of forming the adhesive layer is a pouch manufactured by any one method selected from bar coating, die coating, wire coating, comma coating, micro gravure coating, spray coating, dip coating, spin coating, inkjet coating, roll coating and knife coating. Method of manufacturing a type lithium secondary battery. The method of claim 7, wherein
The thermal compression is a manufacturing method of a pouch type lithium secondary battery that is carried out under the conditions of 40 to 120 ℃ and 1 to 10 atm.