WO2012002746A2

WO2012002746A2 - Separator film for a lithium secondary battery, method for preparing same, and lithium secondary battery comprising same

Info

Publication number: WO2012002746A2
Application number: PCT/KR2011/004799
Authority: WO
Inventors: 문승현; 우중제; 서석준; 윤성현; 남상훈
Original assignee: 광주과학기술원
Priority date: 2010-07-02
Filing date: 2011-06-30
Publication date: 2012-01-05
Also published as: WO2012002746A3; KR20120003203A; KR101235172B1

Abstract

The present invention relates to a separator film for a lithium secondary battery, to a method for preparing same, and to a lithium secondary battery comprising same, and more particularly, to a separator film for a lithium secondary battery, comprising the compound expressed in chemical formula 1. The separator film and the lithium secondary battery comprising same according to the present invention have superior stability, cycle properties, etc.

Description

【Specification】

[Name of invention]

Separation membrane for lithium secondary battery, manufacturing method thereof, and lithium secondary battery comprising same

<1> The present invention relates to a separator for a lithium secondary battery, a method for manufacturing the same, and a lithium secondary battery including the same, more specifically, a lithium secondary battery separator having excellent stability, cycle characteristics, and the like, and a method for manufacturing the same. It relates to a lithium secondary battery comprising the same.

Background Art

<2> A secondary battery is a chemical battery that can repeat layer discharge and discharge using reversible interconversion of chemical energy and electrical energy.

<3> With the recent increase in the use of mobile communication and portable electronic devices and the rapid development of portable electronic devices, the demand for secondary batteries is gradually increasing and the functions required for them are also diversified to maintain their power supply. It is required to reduce the weight, size and capacity of rechargeable batteries.

<4> One of the most recent high-performance, next-generation high-tech batteries that are being used most recently in accordance with such a demand is a lithium secondary battery. Among them, lithium ion battery is excellent enough to occupy more than 60% share of the global secondary battery market, the development of their electrochemical performance is continuing, and many companies and research institutes The focus is on improving performance.

Early lithium secondary batteries were manufactured using lithium metal or a lithium alloy as a negative electrode. However, a secondary battery using lithium metal or a lithium alloy has a problem in that a cycle characteristic is remarkably low because dendrite is formed on a negative electrode as layer discharge is repeated.

To solve the problems associated with the formation of dendrites, a lithium ion battery is proposed. Currently, lithium ion batteries commercially available worldwide are composed of a cathode active material cathode active material, an organic electrolyte and a separator.

The separator serves to prevent internal short circuit caused by the contact between the cathode and the anode of the lithium ion battery and to permeate the ions. Currently, the separator is generally used as polyethylene (PE) or polypropylene ( polypropylene, PP) separator. However, lithium ion batteries using PE or PP separators still have limitations on cell instability, difficulty in battery manufacturing, cell shape constraints, and high capacity. It has a problem such as. Efforts have been made to solve these problems, but no clear results have been made so far.

Research on the preparation of separators that play an important role in the performance and safety of lithium secondary batteries has been made in US Pat. No. 6,413,676. Separation membranes prepared using the polyvinylidene fluoride disclosed by the above literature have high ionic conductivity because of their good affinity with liquid electrolytes, but high mechanical properties due to poor mechanical properties. There was a limit to commercialization as a separator for lithium secondary batteries requiring mechanical properties.

On the other hand, currently commercialized polyethylene membranes have disadvantages such as incompatibility with liquid electrolytes, price increases due to the introduction of a biaxial stretching process, and short supply due to the monopoly of some companies. to be.

[Detailed Description of the Invention]

[Technical problem]

In order to solve the problems of the prior art, the present invention is to provide a lithium secondary battery separator having excellent stability, cycle characteristics and the like, a manufacturing method thereof, and a lithium secondary battery comprising the same.

Technical Solution

In the present invention,

It provides a separator for a lithium secondary battery comprising a compound represented by the formula (1).

[Formula 1]

-Ar1—— 0- ^■ Ar2——

! 1 In Chemical Formula 1,

Arl and Ar2 are each independently an arylene group having 6 to 30 carbon atoms substituted with one or more selected from the group consisting of a halogen group, an alkyl group having 1 to 20 carbon atoms and a haloalkyl group having 1 to 20 carbon atoms,

r is a number from 0 to 1,

n is an integer of 1 to 5,000.

In addition, the present invention 1) preparing a composition comprising a compound represented by Chemical Formula 1 and an organic solvent, and

2) forming a separator using the composition

It provides a method for manufacturing a separator for a lithium secondary battery comprising a <22>.

<23> In addition, the present invention

1) a porous polyolefin membrane, and

2) a coating film provided on both sides of the porous polyolefin-based film, and containing the compound represented by Formula 1

It provides a separator for a lithium secondary battery comprising a <26>.

In addition, the present invention

1) preparing a porous polyolefin-based membrane, and

2) forming a film by coating a composition including a compound represented by Chemical Formula 1 and an organic solvent on both surfaces of the porous polyolefin film;

It provides a method for manufacturing a separator for a lithium secondary battery comprising a <30>.

The present invention also provides a lithium secondary battery comprising the separator for a lithium secondary battery.

Advantageous Effects

Since the separator for a lithium secondary battery according to the present invention includes the compound represented by Chemical Formula 1, the polarity may be increased, so that the lithium secondary battery separator is excellent in wettability to the electrolyte and excellent in thermal stability. In addition, the lithium secondary battery including the separator not only has excellent performance but also excellent cycle characteristics.

【Brief Description of Drawings】

1 is a view schematically showing a lithium secondary battery according to one embodiment of the present invention.

FIG. 2 is a view schematically showing a form of an electrolyte of a conventional lithium secondary battery.

3 is a diagram showing an electrophotographic photo of a separator for a lithium secondary battery according to one embodiment of the present invention.

4 is a view schematically showing the electronic structure of the PP0 and BPP0 unit molecules according to one embodiment of the present invention.

5 is a potential according to the capacity of a lithium secondary battery according to one embodiment of the present invention.

It is a figure which shows (potential).

6 illustrates cycle characteristics of a lithium secondary battery according to one embodiment of the present invention. It is also.

FIG. 7 is a diagram illustrating electron photographs of Celgard 2325 (PP / PE / PP), which is a conventional separator for lithium secondary batteries.

FIG. 8 is a diagram illustrating temperature resistance of Celgard 2325 (PP / PE / PP), which is a conventional separator for lithium secondary batteries.

9 is a view showing the thermal shrinkage of the separator for a lithium secondary battery according to an embodiment of the present invention.

10 is a view showing the thermal stability of the separator for a lithium secondary battery according to an embodiment of the present invention.

[Form for implementation of invention]

Hereinafter, the present invention will be described in more detail.

In the lithium secondary battery, the separator must satisfy various requirements as follows. High ion permeability and low electrical resistance at operating temperature, support for large amount of electrolyte solution and wettability for electrolyte, electrical insulator for positive and negative electrodes, chemical stability for electrolyte solution, electrochemical stability, battery assembly and use Layered physical, mechanical strength, affinity with electrodes, high workability, thin film thickness to enable high density charging for high capacity, Shutdown characteristics (or meltdown characteristics), where shutdown characteristics are short circuits in charged cells The potential difference between the positive and negative poles is sharply narrowed, which causes exothermic reactions and the decomposition of the electrolyte, which can lead to the generation and explosion of gases such as methane, hydrogen, and carbon dioxide. By delaying the battery reaction and heat reaction to ensure stability Say.

In addition, in order to ensure high permeability and conductivity for lithium ions, the separator preferably includes a porous material having a predetermined pore size.

The pores are connected to each other and filled with an electrolyte solution, thereby providing conductivity to charged ion particles. At this time, even if the pore structure is a complicated intertwined path, high battery performance is observed when it has high ion mobility. Therefore, in order to secure high diffusivity within the pore structure, a high porosity that can fill a large amount of electrolyte, and a continuous pore structure that is easy to transfer charges to surface ion particles (eg, lithium ions). And physical factors such as uniform pore size distribution that exhibit a constant lithium ion diffusion coefficient should be optimized.

Therefore, the study of the separator for lithium secondary batteries has shown that pores in the range of A to The key is to produce microporous polymer thin film with size.

The shape of the electrolyte of the conventional lithium secondary battery is schematically shown in FIG. 2. 2 shows an electrolyte of a lithium solid polymer battery, (b) shows an electrolyte of a lithium hybrid polymer battery, and (c) shows an electrolyte of a liquid lithium ion battery.

Meanwhile, a representative example of a separator of a conventional lithium secondary battery is shown in Table 1 below.

<50> [Table 1]

<51>

As shown in Table 1, polypropylene, polyethylene, and polyvinylidene fluoride used as a separator for a conventional lithium secondary battery showed low thermal stability and required various additives.

Thus, one embodiment of the separator for a lithium secondary battery according to the present invention includes a compound represented by the following formula (1).

<54> [Formula 1]

In Chemical Formula 1,

Arl and Ar2 are each independently an arylene group having 6 to 30 carbon atoms substituted with one or more selected from the group consisting of a halogen group, an alkyl group having 1 to 20 carbon atoms and a haloalkyl group having 1 to 20 carbon atoms, R is a number from 0 to I,

N is an integer from I to 5,000.

In Formula I, at least one of the functional groups substituted with Arl or Ar2 is more preferably a halogenated group or a halohaloalkylalkyl group having 2,200 carbon atoms.

<6i> In the separation membrane for lithium lithium secondary battery according to the present invention, the compound represented by Chemical Formula I is represented by the following chemical formula 22 Could be ...

<62> [Γ Chemical Formula 22] 1

In Chemical Formula 2,

At least one of R1 to R8 is a halogen group or a haloalkyl group,

And the rest are each independently selected from the group consisting of hydrogen, a halogen group, an alkyl group having 1 to 20 carbon atoms, and a haloalkyl group having 1 to 20 carbon atoms,

R is a number from 0 to 1,

N is an integer of 1 to 5,000.

In addition, in the separator for a lithium secondary battery according to the present invention, the compound represented by Chemical Formula 1 may be represented by the following Chemical Formula 3.

<70> 3]

In Chemical Formula 3, r is a number from 0 to 1, n is an integer of 1 to 5,000. In Formula 3, r is more preferably a number of 0.85 to 0.99. In the present invention, specific examples of the halogen group include fluorine (F) and chlorine.

(C1), bromine (Br), and more preferably bromine (Br), but only It doesn't happen.

In the present invention, specific examples of the alkyl group include methyl, ethyl, propyl, isobutyl, sec-butyl, tert-butyl, pentyl, iso-amyl, nucleosil, heptyl, and jade. And a methyl group, a stearyl group, a trichloromethyl group, a trifluoromethyl group, etc .; a methyl group, an ethyl group, a propyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an iso-amyl group, a nucleus It is more preferable that it is a real group heptyl group, etc., It is not limited only to this. In the present invention, specific examples of the haloalkyl group include fluorine (F) and chlorine.

Methyl group, ethyl group, propyl group, isobutyl group etc. which were substituted by (C1) or bromine (Br) are mentioned, It is not limited to this.

In the present invention, specific examples of the arylene group may include a phenylene group, a biphenylene group, a naphthalene group, an anthracene group, a phenanthrene group, and the like, and are preferably phenylene groups, but are limited thereto. It is not.

Conventional separators for lithium secondary batteries have low wettability with respect to the liquid electrolyte due to hydrophobic and nonpolar characteristics. However, since the compound represented by Chemical Formula 1 according to the present invention may have a non-symmetric polymer structure as shown in FIG. 4, the polarity of the polymer may be improved, and thus, may exhibit high wettability characteristics with respect to the electrolyte. have.

The separator for a lithium secondary battery according to the present invention may further include a layering agent to enhance porosity, mechanical strength, and the like, and examples thereof include Ti0 ₂ , BaTiOs, Li ₂ 0,

LiF, LiOH, LisN, BaO, N 0, MgO, Li ₂ C0 _3L LiA10 ₂ , Si0 ₂ , A1 ₂ 0 ₃₎ PTFE, a mixture thereof, and the like, but are not limited thereto. The content of the filler is preferably 20% by weight or less based on the total weight of the separation membrane.

In addition, one embodiment of a method for producing a separator for a lithium secondary battery according to the present invention is 1) preparing a composition comprising a compound represented by the formula (1) and an organic solvent, and 2) using the composition To form a separator.

In the method of manufacturing a separator for a lithium secondary battery according to the present invention, the organic solvent of step 1) may be one known in the art, and more specifically, propylene carbonate, butylene carbonate, 1, 4- Butyrolactone, diethyl carbonate, dimethyl carbonate, 1,2-dimethicethane, 1,3-dimethyl-2-imidazole lidinone, dimethyl sulfoxide, ethylene carbonate, ethylmethyl carbonate, Ν, Ν-dimethylform Amides, Ν, Ν-dimethylacetamide, Ν-methyl-2-pyridone, polyethylenesulfuran, tetraethylene glycol dimethyl ether, acetone, alcohols, mixtures thereof, and the like, but are not limited thereto. Is not.

In the method of manufacturing a separator for a lithium secondary battery according to the present invention, the separator of step 2) may be a method known in the art, and more specifically, a phase transfer method, a casting method, an extrusion molding method, Charge-induced radiation may be used, but is not limited thereto.

Formation of the porous polymer membrane is accomplished by the phase transition method. More specifically, the polymer solution dissolved in the organic solvent forming the polymer separator may be cast in the form of a film and then exposed to a non-solvent to prepare a solidified porous membrane. The pore structure of the porous separator can be arbitrarily adjusted by changing the composition of the polymer solution and the contact conditions with the non-solvent.

Formation of the porous polymer membrane is usually accomplished by the charge induction radiation method. More specifically, a polymer solution dissolved in a molten polymer or an organic solvent forming a polymer separator is introduced into a barrel of a charge induction spinning device, a high voltage is applied to a nozzle, and then a metal plate or a mylar film is formed at a predetermined rate. The porous polymer membrane can be prepared by discharging the same. The thickness of the porous separator can be arbitrarily adjusted by changing the discharge speed and the discharge time, and the appropriate thickness is in the range of 1 to 100 / ΛΠ as described above. When using this method, it is possible to directly prepare a separator in which the polymer forming the separator is not a fiber but three-dimensionally stacked fibers having a diameter of 1 to 3000 nm. If necessary, a highly porous separator may be directly formed on the electrode. Therefore, despite the fibrous manufacturing method, the final product can be manufactured directly in the form of a film instead of the fiber, so that no additional device is required, and the manufacturing process is simplified to improve economic efficiency.

In the present invention, in order to further improve the mechanical strength and the like of the separator for lithium secondary batteries, a conventional porous polyolefin resin may be further included. More specifically, the separator for a lithium secondary battery according to the present invention may be provided on both sides of a conventional porous polyolefin-based membrane.

That is, one specific example of the separator for a lithium secondary battery according to the present invention is 1) a porous polyol-resin-based membrane, and 2) a coating membrane provided on both sides of the porous polyolefin-based membrane and containing the compound represented by Chemical Formula 1 Contains

The porous polyolefin-based membrane may be one known in the art, and more specifically, a polyethylene membrane, a polypropylene membrane, or the like may be used, and more preferably, it is a polyethylene membrane, but is not limited thereto.

That is, the separation membrane of the three-layer structure including a polyethylene membrane which is one embodiment of the present invention, If the temperature rises while the battery is running, the polyethylene film in the middle melts and interferes with ion transfer, thereby allowing the battery to have a shutdown function at a high temperature. At this time, as the temperature difference between the intermediate melting polymer and the coated polymer increases, the battery has a high stability. Therefore, in the present invention, since the thermal stability of the coating film including the compound represented by Chemical Formula 1 is very excellent up to 200 ^° C., it is possible to effectively prevent contact between both electrodes during melting of the polyethylene film at a rapid temperature rise.

2) The thickness of the coating film is preferably 1 ~ 30 / m, but is not limited thereto.

In addition, one embodiment of the method for manufacturing a separator for a lithium secondary battery according to the present invention includes the steps of 1) preparing a porous polyolefin-based membrane, and 2) a compound represented by Chemical Formula 1 on both sides of the porous polyolefin-based membrane; Coating a composition comprising an organic solvent to form a film.

<9i> The method for forming the polyolefin-based film of step 1), the organic solvent, and the film of step 2) is the same as described above. In particular, after coating the composition comprising the compound represented by the formula (1) and the organic solvent, the first phase transition by injecting nitrogen gas of 90% or more relative humidity, and the second phase transition by dipping in distilled water, to form a film can do.

In addition, the present invention provides a lithium secondary battery including the separator for a lithium secondary battery.

The lithium secondary battery may include a cathode, an electrolyte, a cathode, and the like known in the art, in addition to the separator for a lithium secondary battery according to the present invention.

Materials that can be used as the positive electrode material of the lithium secondary battery include the following conditions, for example, performing reversible electrochemical reaction with lithium ions, chemical stability with respect to electrolyte, low volume change during layer transfer and discharge, and fast layer. It is desirable to satisfy the discharge rate, a sufficiently high reduction potential with respect to lithium, and the like.

Satisfies these conditions are mainly transition metal oxides LixCo0 ₂ , LixNi0 ₂ ,

LixMn ₂ 0 _4, LiNixCox0 and the _second place, the synthesis is easy and the potential change is gentle, and generally used is excellent in conductivity LiCo0 ₂ as a positive electrode material for a lithium secondary battery.

The basic requirement of the material used as the negative electrode of the lithium secondary battery, for example, should have a potential close to the standard electrode potential of lithium metal, energy density per volume, weight per weight Should be high, excellent cycle stability (high coolant efficiency) should be ensured, be able to withstand high rate charge and discharge capability, and stability should be guaranteed.

Lithium alloy or carbonaceous material is the best material that can satisfy all of these requirements, and carbonaceous material can be recognized as a suitable material because of its small volume change, reversibility, and price advantages. Specific examples of the carbonaceous material include graphite, coke fiber, pitch, meso carbon, and the like.

The electrolyte is a non-aqueous electrolyte containing a lithium salt and an organic solvent. Lithium salts include LiC10 ₄ , LiCF ₃ S0 ₃₎ LiAsF ₆ , LiBF ₄ , LiN (CF ₃ S0 ₂ ) ₂ , LiPF ₆ , LiSCN,

LiC (CF ₃ S0 ₂ ) ₃ , LiBOB and the like are used, and organic solvents include ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and gamma butyrolactone (YBL). , Ethylmethyl carbonate (EMC), dimethoxyethane (DME), diethoxyethane (DEE), 2-methyl tetrahydrofuran (2-MeTHF), dimethyl sulfoxide (DMS), etc. can be used, respectively, or in combination. .

Hereinafter, preferred examples will be presented to aid in understanding the present invention. However, the following examples are merely provided to more easily understand the present invention, and the contents of the present invention are not limited thereto.

<100> <Example>

<ιοι> <Example 1>

1) Preparation of Separator

2 g of BPPO (brominated poly (phenylene oxide)) was dissolved in 8 ml of N-methyl-2-pyrrolidone and 2 ml of butane was further stirred to obtain a polymer solution. After the obtained polymer solution was cast on a glass plate, nitrogen gas was injected with a relative humidity of 90% or more, and the first phase transition was performed for 10 minutes. After that, the secondary phase transition was carried out by storing in distilled water for 12 hours to prepare a porous polymer membrane film.

An electrophotograph of the prepared lithium secondary battery separator is shown in FIG. 3.

2) Fabrication of Lithium Secondary Battery

The separatorol prepared in 1) was placed between Li metal and LiFeP0 ₄ to form a CR2032 coin cell type battery. The electrolyte solution was injected with an EC-DEC solution in which 1M LiPF ₆ was dissolved. All of the cell assembly was performed in a glove box with Ar gas layered. <107><Comparative Example 1>

<io8> An electrophotograph of Celgard 2325 (PP / PE / PP), which is a conventional separator for a conventional lithium secondary battery, is shown in FIG. 7. In addition, the resistance to the temperature of the Celgard 2325 (PP / PE / PP) is shown in Figure 8 below.

<109> <Experimental Example>

<πο> The affinity and ionic conductivity of the electrolyte of the separator for lithium secondary battery according to Example 1 and Celgard 2325 (PP / PE / PP), which is a conventional separator for lithium secondary batteries, were measured and shown in Table 2 below.

<ιιι> [Table 2]

<112>

The potential according to the capacity of the lithium secondary battery of Example 1 and the potential according to the capacity of the lithium secondary battery including the conventional polypropylene separator are shown in FIG. 5. From the results of FIG. 5, it can be seen that the lithium secondary battery according to the present invention exhibits high energy efficiency and output.

In addition, the cycle characteristics of the lithium secondary battery of Example 1 and the cycle characteristics of the lithium secondary battery including a conventional polypropylene separator is shown in Figure 6 below. From the results of furnace 6, it can be seen that the lithium secondary battery according to the present invention has a high relative capacity ratio and a high cool cylinder efficiency.

Thermal shrinkage of the separator for a lithium secondary battery according to Example 1 and Celgard 2325 (PP / PE / PP), which is a separator for a conventional lithium secondary battery, is shown in FIG. 9, and after heating to 200 ^° C. The stability is shown in FIG. 10.

From the experimental results, it can be seen that the lithium secondary battery separator according to the present invention includes the compound represented by Chemical Formula 1, thereby increasing polarity, thereby providing excellent wettability to the electrolyte and excellent thermal stability. Can be. In addition, the lithium secondary battery including the separator according to the present invention not only has excellent performance but also has excellent cycle characteristics.

Claims

Claims Claim 11 Separation membrane for a lithium secondary battery containing a compound represented by the following formula (1):

[ One]

In Chemical Formula 1,

r is a number from 0 to 1,

n is an integer of 1 to 5,000.

[Claim 2]

The method of claim 1,

Compound represented by the formula (1) is a lithium secondary battery separator, characterized in that represented by the formula (2):

[Formula 2]

In Chemical Formula 2,

At least one of R1 to R8 is a halogen group or a haloalkyl group,

The rest are each independently selected from the group consisting of hydrogen, a halogen group, an alkyl group having 1 to 20 carbon atoms, and a haloalkyl group having 1 to 20 carbon atoms,

r is a number from 0 to 1,

n is an integer of 1-5,000.

[Claim 3] The method of claim 1,

Compound represented by the formula (1) is a lithium secondary battery separator, characterized in that represented by the formula (3):

[3]

In Formula 3, r is a number of 0 to 1, n is an integer of 1 to 5,000.

[Claim 4]

The method of claim 1,

The lithium secondary battery separator is a lithium secondary battery separator, characterized in that it further comprises a layering agent.

[Claim 5]

The method of claim 4,

The layering agent is Ti0 ₂ , BaTi0 ₃₎ Li ₂ 0, LiF, LiOH, L1 ₃ N, BaO, Na ₂ 0, MgO,

Li ₂ CO ₃₎ LiA 10 ₂ , Si0 ₂ , A1 ₂ 0 ₃ , PTFE and a separator for a lithium secondary battery comprising at least one selected from the group consisting of a mixture thereof.

[Claim 6]

1) preparing a composition comprising a compound represented by the following formula (1) and an organic solvent, and

2) forming a separator using the composition

Method for manufacturing a separator for a lithium secondary battery comprising:

[ One]

In Chemical Formula 1,

Arl and Ar2 are each independently a halogen group, an alkyl group having 1 to 20 carbon atoms and carbon An arylene group having 6 to 30 carbon atoms substituted with one or more selected from the group consisting of a small number of 1 to 20 haloalkyl groups,

r is a number from 0 to 1,

n is an integer from 1 to 5,000.

[Claim 7]

The method of claim 6,

The organic solvent of step 1) is propylene carbonate, butylene carbonate, 1,4-butyrolactone, diethyl carbonate, dimethyl carbonate, 1,2-dimethoxyethane, 1,3-dimethyl-2-imidazole lididi Paddy, dimethyl sulfoxide, ethylene carbonate, ethylmethyl carbonate, Ν, Ν-dimethylformamide, Ν, Ν-dimethylacetamide, Ν-methyl-2-pyridone, polyethylene sulfolane, tetraethylene glycol dimethyl A method for producing a separator for a lithium secondary battery, characterized in that it comprises one or more selected from the group consisting of ether, acetone, alcohol and mixtures thereof.

[Claim 8]

The method of claim 6,

Forming the separator of step 2) is a method of manufacturing a separator for a lithium secondary battery, characterized in that using a method selected from the group consisting of a phase transfer method, casting method, extrusion molding method and charge induction spinning method.

[Claim 9]

1) porous polyolefin-based membrane, and

2) a coating film provided on both sides of the porous polyolefin-based film, and containing a compound represented by the following formula (1)

Separation membrane for a lithium secondary battery comprising:

[Formula 1]

In Chemical Formula 1,

Arl and Ar2 are each independently an arylene group having 6 to 30 carbon atoms substituted with one or more selected from the group consisting of a halogen group, an alkyl group having 1 to 20 carbon atoms and a haloalkyl group having 1 to 20 carbon atoms, r is a number from 0 to 1,

n is an integer of 1 to 5,000.

[Claim 10]

The method according to claim 9,

1) The porous polyolefin-based membrane is a separator for a lithium secondary battery, characterized in that it comprises a polystyrene membrane or a polypropylene membrane.

[Claim 11]

The method of claim 19,

2) The thickness of the coating membrane is a lithium secondary battery separator, characterized in that 1/30 / m.

[Claim 12]

1) preparing a porous polyolefin film, and

2) forming a membrane by coating a composition comprising a compound represented by the following formula (1) and an organic solvent on both sides of the porous polyolefin-based membrane

[Formula 1]

-Ar1 一 0- -Ar2 ᅳ 0-

(1 -Γ) in the formula 1,

r is a number from 0 to 1,

n is an integer of 1 to 5,000.

[Claim 13]

A lithium secondary battery comprising the separator for a lithium secondary battery of any one of claims 1 to 5 and 9 to 11.