KR101360366B1 - Electrode Assembly and Secondary battery having the Same - Google Patents

Abstract

The present invention relates to an electrode assembly and a secondary battery having the same, wherein the electrode assembly includes a positive electrode having a positive electrode active material layer; A negative electrode having a negative electrode active material layer; And a separator separating the positive electrode and the negative electrode, wherein the separator comprises a polyethylene resin including a metallocene polyethylene, an organicated montmorillonite, and a compatibilizer in which an ethylenically unsaturated carboxylic anhydride is grafted onto a polyethylene main chain. It is done.

Therefore, the separator according to the present invention has an effect of providing a secondary battery having high safety by preventing melting and shrinkage of the separator during heat generation inside the secondary battery due to its high flexural strength and tensile strength.

Separator, Polyethylene, Flexural Strength, Tensile Strength

Description

Electrode assembly and secondary battery having same {Electrode Assembly and Secondary battery having the Same}

The present invention relates to an electrode assembly and a secondary battery having the same, and more particularly, to a polyethylene resin including a metallocene polyethylene, an organicated montmorillonite, and a compatibilizer in which an ethylenically unsaturated carboxylic anhydride is grafted onto a polyethylene main chain. The present invention relates to a secondary battery having a separator having high tensile strength and flexural strength.

As miniaturization and light weight of portable electronic devices have recently advanced, the necessity for miniaturization and high capacity of batteries used as driving power sources thereof is increasing. In particular, the lithium secondary battery has an operating voltage of 3.6 V or more, which is three times higher than that of a nickel-cadmium battery or a nickel-hydrogen battery, which is widely used as a power source for portable electronic devices, and rapidly expands in terms of high energy density per unit weight. There is a trend.

Lithium secondary batteries generate electrical energy by oxidation and reduction reactions when lithium ions are intercalated / deintercalated at the positive and negative electrodes. A lithium secondary battery is prepared by using a material capable of reversibly intercalating / deintercalating lithium ions as an active material of a positive electrode and a negative electrode, and filling an organic electrolyte or a polymer electrolyte between the positive electrode and the negative electrode.

The lithium secondary battery includes an electrode assembly in which a negative electrode plate and a positive electrode plate are wound in a predetermined form, for example, in a jelly-roll form with a separator interposed therebetween, a can containing the electrode assembly and the electrolyte, And a cap assembly assembled on the upper part.

The positive electrode plate of the electrode assembly is electrically connected to the cap assembly through the positive electrode lead, and the negative electrode plate of the electrode assembly is electrically connected to the can through the negative electrode lead.

The basic function of the separator of the lithium secondary battery is to prevent short circuit by separating the positive electrode and the negative electrode, and further, it is important to maintain high ionic conductivity by sucking the electrolyte necessary for the battery reaction. In particular, in the case of a lithium secondary battery, an additional function is required to prevent the movement of substances that inhibit battery reaction or to ensure safety when an abnormality occurs.

In general, as a material of the separator, a polyolefin-based microporous polymer membrane such as polypropylene or polyethylene or a multilayer thereof is used. Since such a separator has a porous membrane layer in the form of a sheet or a film, an internal short circuit In addition, the sheet-like separator also shrinks or melts due to pore blockage of the porous membrane due to overheating. Therefore, when the sheet-like separator collapses due to the internal heat generation of the battery, the separator is reduced and the missing portion is directly in contact with the positive electrode and the negative electrode, resulting in ignition, rupture, and explosion.

Therefore, it is important to prevent short circuit between electrode plates due to breakage of the separator due to melting and shrinking of the conventional film-like separator due to internal heat generation of the secondary battery, and to prevent ignition, rupture and explosion of the secondary battery. It is emerging.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an electrode assembly including a separator having good flexural strength and tensile strength and a secondary battery having the same.

Another object of the present invention is to provide a secondary battery having improved battery stability through a separator having good flexural strength and tensile strength.

In order to achieve the above object, the present invention is a positive electrode having a positive electrode active material layer; A negative electrode having a negative electrode active material layer; And a separator separating the positive electrode and the negative electrode, wherein the separator comprises a polyethylene resin including a metallocene polyethylene, an organicated montmorillonite, and a compatibilizer in which an ethylenically unsaturated carboxylic anhydride is grafted onto a polyethylene main chain. An electrode assembly and a secondary battery having the same are provided.

In addition, the present invention is the organic montmorillonite is contained in 0.1 to 10 parts by weight with respect to 100 parts by weight of the metallocene-based polyethylene, the compatibilizer in which the ethylenically unsaturated carboxylic anhydride is grafted to the polyethylene backbone is the metallocene-based It provides an electrode assembly and a secondary battery having the same, characterized in that contained in 0.5 to 30 parts by weight based on 100 parts by weight of polyethylene.

The present invention also provides an electrode assembly and a secondary battery having the same, wherein the polyethylene resin further comprises a Ziegler-Natta based polyethylene having a molecular weight of 3000 or less.

In addition, the present invention provides an electrode assembly and a secondary battery having the same, wherein the Ziegler-Natta-based polyethylene having a molecular weight of 3000 or less is contained in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the metallocene-based polyethylene.

In addition, the present invention, the polyethylene resin further comprises at least one additive selected from the group consisting of an acid-resistant, antioxidant, UV stabilizer and processing aid, the additive is based on 100 parts by weight of the metallocene polyethylene It provides an electrode assembly and a secondary battery having the same, characterized in that more than 0 and included in 1 parts by weight or less.

Therefore, the separator according to the present invention has a high flexural strength and tensile strength, thereby preventing the separator from melting and shrinking when the secondary battery generates heat.

In addition, the separator according to the present invention has an effect of providing a secondary battery having high safety by improving overcharge characteristics and thermal exposure characteristics.

Details of the above object and technical configuration of the present invention and the effects thereof will be more clearly understood by the following detailed description of the present invention.

An electrode assembly including the separator of the present invention and a secondary battery having the same will now be described.

First, the separator of the present invention consists of a polyethylene resin comprising a metallocene polyethylene, an organicated montmorillonite, and a compatibilizer in which an ethylenically unsaturated carboxylic anhydride is grafted onto the polyethylene backbone.

The metallocene-based polyethylene according to the present invention represents a copolymer of an ethylene homopolymer and one or more monomers, and monomers that may be used in the present invention are, for example, butene-1, hexene-1, 4- Linear or branched alpha olefins containing 4 to 8 carbon atoms such as methylpentene-1 and octene-1.

Further preferred examples of ethylene copolymers advantageously used in the present invention are copolymers of ethylene and butene or hexene, or optionally copolymers obtained by continuous polymerization of a mixture of ethylene and butene or hexene.

In addition, the ethylene copolymer is preferably a copolymer having two kinds of molecular weight distribution, particularly a copolymer having two distributions obtained by continuous polymerization of ethylene and a mixture of ethylene and butene.

In this case, the polyethylene according to the present invention has a melt index (MI ₅ ) of 0.1g / 10min to 5g / 10min when measured at 190 ° C and 5kg load according to ASTM D 1238, and measured according to ASTM D 1505. High density polyethylenes having a density at 캜 of at least 940 kg / m 3, in particular at least 950 kg / m 3, are suitable.

The organicized montmorillonite according to the present invention corresponds to montmorillonite ion-exchanged with tertiary or quaternary ammonium salts, and for example, a nanoclay's closite (Cloisite trademark) may be used.

The organicized montmorillonite should essentially exhibit a layered structure, the interlaminar distance of the organic montmorillonite is preferably 15 Å or more as measured by XRD. When the distance between the layers is less than 15 μs, polyethylene is difficult to be easily inserted, which makes it difficult to uniformly disperse montmorillonite.

At this time, the organicated montmorillonite is preferably included in 0.1 to 10 parts by weight, more preferably 0.3 to 5 parts by weight based on 100 parts by weight of the metallocene-based polyethylene.

If the content is less than 0.1 parts by weight can not exhibit a sufficient effect according to the present invention, if it exceeds 10 parts by weight it is difficult to obtain easy dispersibility and processability.

The compatibilizer according to the present invention is a grafted ethylenically unsaturated carboxylic anhydride to the polyethylene backbone can be prepared by a conventional grafting method. For example, linear low density polyethylene, low density polyethylene, or high density polyethylene with ethylenically unsaturated carboxylic anhydride, together with the reaction initiator, may be extruded through a single or twin screw extruder above the melting temperature of polyethylene, or conventional melt mixing such as batch mixers, etc. It can be prepared by grafting by the reaction extrusion method using the method.

As another example it may be prepared by mixing the ethylenic unsaturated carboxylic anhydride with the reaction initiator to the ethylene monomer in the reactor.

In this case, the compatibilizer in which the ethylenically unsaturated carboxylic anhydride is grafted to the polyethylene main chain is preferably included in an amount of 0.5 to 30 parts by weight based on 100 parts by weight of the metallocene polyethylene.

In addition, the polyethylene resin according to the present invention may further include a low molecular weight polymer.

The low molecular weight polymer is a Ziegler-Natta based polyethylene low molecular weight polymer having a molecular weight of 3000 or less, and represents a copolymer of an ethylene homopolymer and one or more monomers. Examples of the monomer that may be used include butene-1 and hexene. Linear or branched alpha olefins containing 4 to 8 carbon atoms such as -1, 4-methylpentene-1, octene-1 and the like can be used.

In this case, the low molecular weight polymer is preferably included in 0.01 to 5 parts by weight based on 100 parts by weight of the metallocene-based polyethylene.

In addition, the polyethylene resin according to the present invention may contain additives that can be used in the ethylene polymer, and the additives include stabilizers and processing aids such as acid resistant, antioxidant or ultraviolet stabilizers. At this time, the content of these additives is generally 1 part by weight or less, preferably 0.5 parts by weight or less, based on 100 parts by weight of polyethylene.

The method for preparing a composition according to the present invention is a metal bisene-based high-density polyethylene, organic montmorillonite, a compatibilizer, a Ziegler-Natta-based polyethylene having a molecular weight of 3000 or less, an antioxidant, and an antioxidant using a Henschel mixer. After uniformly dispersing, it may be prepared by melt extrusion into a main feed portion of an extruder at a temperature of 150 to 220 ℃.

Next, an electrode assembly including the separator of the present invention and a secondary battery having the separator include a positive electrode and a negative electrode.

The positive electrode includes a positive electrode active material capable of reversibly intercalating and deintercalating lithium ions. Typical examples of the positive electrode active material include LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , or LiNi _{1 -} transition metal oxides such as _{x- y} Co _x M _y O ₂ (0 ≤ x ≤ 1, 0 ≤ y ≤ 1, 0 ≤ x + y ≤ 1, and M is a metal such as Al, Sr, Mg, La) However, the present invention does not limit the kind of the cathode active material.

The negative electrode includes a negative electrode active material capable of intercalating and deintercalating lithium ions. As the negative electrode active material, a carbon-based negative active material of a crystalline or amorphous carbon or a carbon composite may be used. The invention does not limit the kind of the negative electrode active material.

Next, the secondary battery including the electrode assembly including the separator of the present invention includes an electrolytic solution.

The electrolyte according to the present invention includes a non-aqueous organic solvent, and the non-aqueous organic solvent may include a carbonate, an ester, an ether, or a ketone. The carbonate is dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methylethyl carbonate (MEC) ethylene carbonate (EC) , Propylene carbonate (PC), butylene carbonate (BC) and the like can be used, the ester is butyrolactone (BL), decanolide (decanolide), valerolactone (valerolactone), mevalonolactone (mevalonolactone ), Caprolactone (caprolactone), n-methyl acetate, n-ethyl acetate, n-propyl acetate and the like can be used, the ether may be dibutyl ether and the like, the ketone is polymethyl vinyl ketone However, the present invention is not limited to the type of non-aqueous organic solvent.

When the non-aqueous organic solvent is a carbonate-based organic solvent, it is preferable to use a mixture of a cyclic carbonate and a chain carbonate. In this case, the cyclic carbonate and the chain carbonate are preferably used in a volume ratio of 1: 1 to 1: 9, more preferably 1: 1.5 to 1: 4. The performance of the electrolyte is preferable when mixed in the above volume ratio.

The electrolytic solution of the present invention may further contain an aromatic hydrocarbon-based organic solvent in the carbonate-based solvent. As the aromatic hydrocarbon-based organic solvent, an aromatic hydrocarbon-based compound may be used.

Specific examples of the aromatic hydrocarbon-based organic solvent include benzene, fluorobenzene, chlorobenzene, nitrobenzene, toluene, fluorotoluene, trifluorotoluene, xylene and the like. In the electrolyte containing an aromatic hydrocarbon-based organic solvent, the volume ratio of the carbonate solvent / aromatic hydrocarbon solvent is preferably 1: 1 to 30: 1. The performance of the electrolyte is preferable when mixed in the above volume ratio.

In addition, the electrolyte according to the present invention includes a lithium salt, and the lithium salt acts as a source of lithium ions in the battery to enable operation of a basic lithium battery. Examples thereof include LiPF ₆ , LiBF ₄ , LiSbF ₆ , _{LiAsF 6, LiClO 4, LiCF 3} SO 3, LiN (CF 3 SO 2) 2, LiN (C 2 F 5 SO 2) 2, LiAlO 4, LiAlCl 4, LiN (C x F 2x +1 SO 2) (CyF _{2 x 1} SO ₂ ) (where x and y are natural numbers), and LiSO ₃ CF ₃ .

At this time, the concentration of the lithium salt can be used in the range of 0.6 to 2.0M, preferably in the range of 0.7 to 1.6M. If the concentration of the lithium salt is less than 0.6M, the conductivity of the electrolytic solution is lowered to deteriorate the performance of the electrolyte. If the concentration exceeds 2.0M, the viscosity of the electrolytic solution increases and the lithium ion mobility decreases.

The separator of the present invention as described above is interposed between the negative electrode and the positive electrode to form an electrode group by laminating or laminating it, and then inserted into a can or similar container, and then an electrolyte is injected to prepare a secondary battery .

Hereinafter, preferred embodiments and comparative examples of the present invention will be described. However, the following embodiments are merely preferred embodiments of the present invention, and the present invention is not limited to the following embodiments.

Example 1

LiCoO2 as a positive electrode active material, polyvinylidene fluoride (PVDF) as a binder and carbon as a conductive agent were mixed in a weight ratio of 92: 4: 4, and then dispersed in N-methyl-2-pyrrolidone to prepare a positive electrode slurry. . The slurry was coated on an aluminum foil having a thickness of 20 μm, dried, and rolled to prepare a positive electrode. Synthetic graphite as a negative electrode active material, styrene-butadiene rubber as a binder, and carboxymethyl cellulose as a thickener were mixed in a weight ratio of 96: 2: 2, and then dispersed in water to prepare a negative electrode active material slurry. This slurry was coated on a copper foil having a thickness of 15 mu m, followed by drying and rolling to prepare a negative electrode.

In addition, 100 parts by weight of metallocene-based high-density polyethylene powder, 1 part by weight of organic montmorillonite Cloisite 20A, 5 parts by weight of maleic anhydride grafting polyethylene as a compatibilizer, 0.05 parts by weight of Ziegler-Natta based polyethylene with a low molecular weight polymer, phenol 0.05 parts by weight of pentaerythritol tetrakis (3- (3,5-ditetbutyl-4-hydroxyphenyl) propionate) as a (Phenol) -based antioxidant, and a tri (Phosphite) as a antioxidant 0.1 part by weight of 2,4-ditetbutylphenyl) phosphite and 0.1 part by weight of calcium stearate were mixed and granulated at a temperature of 210 ° C. using a twin screw extruder (manufactured by JSW, screw diameter 50 mm). The obtained granules had a MI ₅ of 0.50 g / 10 min and a density of 959 kg / m 3. The composition was prepared in a compression sheet and a single-screw type (Battenfield) extruder at a processing temperature of 200 ° C.

The separator was wound between the prepared cathode and the anode and wound and compressed to insert the separator into a rectangular can.

At this time, the metallocene-based polyethylene was used a metallocene-based high-density polyethylene powder containing two molecular weight distribution having a density of 0.50 g / 10 MI ₅ and 950kg / ㎥, the organic montmorillonite is organicized to a quaternary ammonium salt Montmorillonite Clonaite 20A having an interlayer distance of 24 mm 3 was used, and a compatibilizing agent was maleic anhydride grafted polyethylene. At this time, the maleic anhydride grafted polyethylene was prepared by mixing the reaction initiator in the maleic anhydride and high-density polyethylene (density is 950kg / ㎥ and MI ₅ 0.6 high density polyethylene) by melt mixing in a twin screw extruder, MI _{5 of} 0.4 It represents a density of 951kg / ㎥. In addition, the Ziegler-Natta type | system | group polyethylene was used for the molecular weight 2500.

[Example 2]

Except for 10 parts by weight of Cloisite 20A, 30 parts by weight of maleic anhydride grafted polyethylene and 1 part by weight of Ziegler-Natta based polyethylene having a molecular weight of 3000 or less, it was carried out in the same manner as in Example 1.

[Example 3]

Except for 5 parts by weight of Cloisite 20A, 15 parts by weight of maleic anhydride grafted polyethylene and 0.5 parts by weight of Ziegler-Natta based polyethylene having a molecular weight of 3000 or less was carried out in the same manner as in Example 1.

Comparative Example 1

The same procedure as in Example 1 was carried out except that no compatibilizer was used.

[Comparative Example 2]

The same procedure as in Example 2 was conducted except that no compatibilizer was used.

[Comparative Example 3]

The same procedure as in Example 3 was conducted except that no organicated montmorillonite and a compatibilizer were used.

Standard densities and melt indexes, which are the basic physical properties of the separators of Examples 1 to 3 and Comparative Examples 1 to 3, were measured. The standard density (D) was measured at 23 ° C. according to ASTM D 1505 (kg / m 3), and the melt index (MI ₅ ) was measured under a load of 5 kg at 190 ° C. according to ASTM D 1238 (g / 10 min. ).

In addition, the tensile strength and flexural strength of the separators of Examples 1 to 3 and Comparative Examples 1 to 3 were measured. The tensile strength (TS) was measured by the yield point tensile strength by ASTM D 747 with 4mm compression specimen (kg / ㎠), the flexural strength (FM) was measured by ASTM D 747 with 4mm compression specimen (kg / ㎠ ).

In addition, as the characteristics of the secondary batteries of Examples 1 to 3 and Comparative Examples 1 to 3, temperature and thermal exposure characteristics during overcharging were measured. The overcharge temperature (° C.) measured the maximum cell temperature when 1A was charged for 2.5 hours until the fully charged cell reached 5V, and the thermal exposure characteristics of the lithium ion secondary battery in the standard charging state. After entering the chamber, the temperature was increased at a temperature increase rate of 5 ° C. per minute from room temperature to 130 ° C., and the change of the battery was observed while maintaining at 130 ° C. for 1 hour.

At this time, in order to pass the thermal exposure characteristics test to maintain the L1 level below 10 minutes at 130 ℃, specific criteria are as follows.

First, L0 represents a case in which there is no change in appearance, and includes a case in which there is no leakage and only flashes, or a case that is deformed by an impact during the test while maintaining the airtightness of the battery.

L1 is reduced by 0.1% or more of the initial battery weight due to the loss of a part of an internal component such as electrolyte, or when a part that can be destroyed due to battery design, such as a vent, is destroyed, or when the naked eye is checked, If there is a trace of eruption. To check for leakage, the weight after the test must be measured and compared with the initial weight, but in the case of safety test items, this can be omitted. This includes a case in which the instrument of the battery is destroyed by the impact during the test without any smoke, gas (gas) ejection, or ignition, and leakage of the internal electrolyte.

L2 refers to a state in which smoke does not accompany thermal runaway and the surface temperature of the battery does not exceed 200 ° C., which refers to the case of steam generation from inside the battery.

L3 exhibits a condition in which the battery surface temperature exceeds 200 ° C due to thermal runaway, even if smoke accompanied by thermal runaway occurs, the battery surface temperature exceeds 200 ° C, the gas is released violently, or no signs of smoke are observed. Say.

L4 refers to a state in which the contents of the battery are self-ignited and sparks are burned and burned.

L5 refers to a state in which the internal structure is released by the pressure from the inside of the battery, and the battery case is destroyed except for a portion where the battery case may be destroyed in the battery design, thereby debris is released.

The measurement results are shown in Tables 1 and 2 below.

[Table 1]

division Example 1 Example 2 Example 3

Separator
Furtherance Metallocene Polyethylene 100 100 100 Organized Montmorillonite One 10 5 Compatibilizer 5 30 15 Low molecular weight polymer 0.05 One 0.5 Phenolic antioxidant 0.05 0.05 0.05 Phosphite-based antioxidant 0.1 0.1 0.1 Calcium stearate 0.1 0.1 0.1 Separator
Basic property Melt Index 0.52 0.58 0.55 Standard density 0.958 0.964 0.962
characteristic The tensile strength 263 265 273 Flexural strength 16750 16150 16800 Temperature at overcharge 50 40 45 Thermal exposure characteristics L0 (130 degreeC) L0 (130 degreeC) L0 (130 degreeC)

[Table 2]

division Comparative Example 1 Comparative Example 2 Comparative Example 3

Separator
Furtherance Metallocene Polyethylene 100 100 100 Organized Montmorillonite One 10 0 Compatibilizer 0 0 0 Low molecular weight polymer 0.05 One 0.5 Phenolic antioxidant 0.05 0.05 0.05 Phosphite-based antioxidant 0.1 0.1 0.1 Calcium stearate 0.1 0.1 0.1 Separator
Basic property Melt Index 0.56 0.65 0.65 Standard density 0.958 0.961 0.956
characteristic The tensile strength 120 123 155 Flexural strength 9820 9010 16600 Temperature at overcharge 300 300 250 Thermal exposure characteristics L3 (over 200 ℃) L3 (over 200 ℃) L3 (over 200 ℃)

From the results shown in Tables 1 and 2 above, it can be seen that the tensile strength and flexural strength are higher than those of Comparative Examples 1 to 3 of Examples 1 to 3, and the battery stability is significantly improved due to the low temperature during overcharging.

In addition, in the thermal exposure characteristics of the battery, the thermal exposure characteristics are excellent in the case of Examples 1 to 3 corresponding to L0, but in the case of Comparative Examples 1 to 3 correspond to L3, in particular, the battery surface temperature is 200 ℃ It can be seen that the heat exposure characteristics are not good.

Therefore, the separator made of the metallocene polyethylene, the organicized montmorillonite, and the polyethylene resin including the compatibilizer in which the ethylenically unsaturated carboxylic anhydride is grafted to the polyethylene main chain has high tensile strength and flexural strength. Significantly low temperature during overcharging can improve battery stability, and is also excellent in thermal exposure characteristics.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, Various changes and modifications will be possible.

Claims (11)

A positive electrode having a positive electrode active material layer; A negative electrode having a negative electrode active material layer; Separation of the positive electrode and the negative electrode, a metallocene-based polyethylene, organic montmorillonite and ethylenically unsaturated carboxylic anhydride comprises a separator comprising a polyethylene resin comprising a compatibilizer grafted on the polyethylene backbone, The organicized montmorillonite is included in 0.1 to 10 parts by weight based on 100 parts by weight of the metallocene-based polyethylene, The compatibilizer in which the ethylenically unsaturated carboxylic anhydride is grafted to the polyethylene main chain is 0.5 to 30 parts by weight based on 100 parts by weight of the metallocene polyethylene. delete The method of claim 1, The polyethylene resin is an electrode assembly, characterized in that further comprises a Ziegler-Natta-based polyethylene having a molecular weight of 3000 or less. The method of claim 3, wherein The Ziegler-Natta-based polyethylene having a molecular weight of 3000 or less is 0.01 to 5 parts by weight based on 100 parts by weight of the metallocene-based polyethylene. The method of claim 1, The polyethylene resin further includes at least one additive selected from the group consisting of an acid resistant agent, an antioxidant, a UV stabilizer, and a processing aid, wherein the additive exceeds 0 with respect to 100 parts by weight of the metallocene polyethylene 1 Electrode assembly, characterized in that included in less than. In a secondary battery comprising a positive electrode, a negative electrode, a separator for separating the two electrodes and an electrolyte solution, The separator consists of a polyethylene resin comprising a metallocene-based polyethylene, an organicated montmorillonite and a compatibilizer in which ethylenically unsaturated carboxylic anhydrides are grafted onto the polyethylene backbone, The organicized montmorillonite is included in 0.1 to 10 parts by weight based on 100 parts by weight of the metallocene-based polyethylene, The compatibilizer in which the ethylenically unsaturated carboxylic anhydride is grafted to the polyethylene main chain is 0.5 to 30 parts by weight based on 100 parts by weight of the metallocene-based polyethylene. delete The method of claim 6, The polyethylene resin further comprises a Ziegler-Natta-based polyethylene having a molecular weight of 3000 or less. 9. The method of claim 8, The secondary battery of the Ziegler-Natta-based polyethylene having a molecular weight of 3000 or less is contained in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the metallocene-based polyethylene. The method of claim 6, The polyethylene resin further includes at least one additive selected from the group consisting of an acid resistant agent, an antioxidant, a UV stabilizer, and a processing aid, wherein the additive exceeds 0 with respect to 100 parts by weight of the metallocene polyethylene 1 Secondary battery, characterized in that included in less than. The method of claim 6, The electrolyte solution is a secondary battery comprising a non-aqueous organic solvent and a lithium salt.