WO2016021987A1

WO2016021987A1 - Separator for lithium secondary battery, and lithium secondary battery containing same

Info

Publication number: WO2016021987A1
Application number: PCT/KR2015/008305
Authority: WO
Inventors: 서동완; 고창홍; 진목연; 배임혁
Original assignee: 삼성에스디아이 주식회사
Priority date: 2014-08-08
Filing date: 2015-08-07
Publication date: 2016-02-11

Abstract

Provided are: a separator for a lithium secondary battery, comprising a substrate and a heat resistant porous layer, which is located on at least one surface of the substrate and comprises a polymer having a structural unit represented by chemical formula 1; and a lithium secondary battery containing the same.

Description

【Specification】

[Name of invention]

Separator for lithium secondary battery and lithium secondary battery comprising same

Technical Field

The present invention relates to a separator for a lithium secondary battery and a lithium secondary battery including the same.

Background Art

Recently, the need for electrons having high energy density as a power source for portable electronic devices has increased, and research of lithium secondary batteries has been actively conducted. In addition, as interest in environmental problems grows, research on electric vehicles is being conducted, and researches using lithium secondary batteries as a power source of electric vehicles are also actively conducted.

Such a lithium secondary battery includes a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode. The separator includes micropores, which not only move lithium ions through the pores, but also electrically insulate between the anode and the cathode.

These separators are required to be made thinner and lighter in weight, and at the same time heat form for the production of high capacity batteries, due to the recent trend of light weight and miniaturization of batteries and the need for high output large capacity batteries for use in electric vehicles. Excellent stability is required.

For this purpose, a separator formed by coating a binder resin and ceramic particles on a porous substrate is used. However, when overheated, it is difficult to secure stability due to shrinkage of the separator.

[Content of invention]

[Problem to solve]

One embodiment is to provide a separator for a lithium secondary battery excellent in flame retardancy, heat resistance, oxidation resistance and breathability.

Another embodiment is to provide a lithium secondary battery having excellent stability and performance including the separator ᅳ

[Measures of problem] One embodiment provides a separator for a rechargeable lithium battery including a substrate and a heat resistant porous layer including a polymer disposed on at least one surface of the substrate and having a structural unit represented by the following Chemical Formula 1.

[Formula 1]

In Chemical Formula 1,

X is a single bond, -CO-, -S0 _2- , -COO-, -CONR'- (R 'is a substituted or unsubstituted C1 to C20 alkyl group, or a substituted or unsubstituted C6 to C30 aryl group),- POR "-(R '' is a hydrogen atom, a substituted or unsubstituted C1 to C20 alkyl group, or a substituted or unsubstituted C6 to C30 aryl group), a substituted or unsubstituted C1 to C20 alkylene group, a substituted or unsubstituted C2 to C20 alkenylene group, substituted or unsubstituted C2 to C20 alkynylene group, substituted or unsubstituted C3 to C20 cycloalkylene group, substituted or unsubstituted C3 to C20 cycloalkenylene group, substituted or unsubstituted C4 To C20 cycloalkynylene group, substituted or unsubstituted C6 to C30 arylene group, substituted or unsubstituted fluorenylene group, substituted or unsubstituted C1 to C20 alkylidene group, substituted or unsubstituted C3 to C20 cycloalkyl Leeden group, substituted or unsubstituted phthalidylidene group, substituted or An unsubstituted fluorenylidene group, or at least one of -CO-, -S0 _2- , -COO-, and -CONR'- is a linking group derived from a spiro compound included in the chain,

Z is a single bond or an oxygen atom,

R ¹ is a hydrogen atom, substituted or unsubstituted C1 to C20 alkyl group, substituted or unsubstituted C2 to C20 alkenyl group, substituted or unsubstituted C2 to C20 alkynyl group, substituted or unsubstituted C3 to C20 cycloalkyl group, substituted Or an unsubstituted C3 to C20 cycloalkenyl group, a substituted or unsubstituted C4 to C20 cycloalkynyl group, or a substituted or unsubstituted C6 to C30 aryl group,

n is an integer of 3 to 1000.

Another embodiment provides a lithium secondary battery including the separator. Specific details of other embodiments are included in the following detailed description. 【Effects of the Invention】

By providing a separator having excellent flame retardancy, heat resistance, oxidation resistance, and breathability, a lithium secondary battery having excellent stability and performance can be implemented.

[Brief Description of Drawings]

1 is an exploded perspective view of a rechargeable lithium battery according to one embodiment.

[Specific contents to carry out invention]

Hereinafter, embodiments of the present invention will be described in detail. However, this is presented as an example, by which the present invention is not limited and the present invention is defined only by the scope of the claims to be described later.

Unless otherwise defined herein, 'substituted' means that a hydrogen atom of a compound compound is a halogen atom (F, Br, CI, I), a hydroxyl group, an alkoxy group, a nitro group, a cyano group, an amino group, an azido group, an amino group Dino group, hydrazino group, hydrazono group, carbonyl group, carbamyl group, thi group, ester group, carboxyl group or salt thereof, sulfonic acid group or salt thereof, phosphoric acid group or salt thereof C1 to C20 alkyl group, C2 to C20 alkenyl group, C2 C20 to C20 alkynyl group, C6 to C30 aryl group, C7 to C30 arylalkyl group, C1 to C20 alkoxy group, C1 to C20 heteroalkyl group, C3 to C20 heteroarylalkyl group, C3 to C20 cycloalkyl group, C3 to C20 cycloalkenyl group, C4 to C20 cycloalkynyl group, C2 to C20

Substituted with a substituent selected from a heterocycloalkyl group and combinations thereof. In addition, unless otherwise defined herein, "hetero" means all those containing 1 to 3 heteroatoms selected from N, 0, S and P.

Hereinafter, a separator for a rechargeable lithium battery according to one embodiment is described.

The separator of the present embodiment separates the negative electrode from the positive electrode and provides a passage for moving lithium ions, and may include a substrate and a heat-resistant porous layer positioned on at least one surface of the substrate.

The substrate may be porous, including voids. Lithium ions may move through the pores. The substrate may be made of polyethylene, polypropylene, or the like.

Polyolefin, polyester, polytetrafluoroethylene (PTFE), glass fibers or combinations thereof can be used. Among them, for example, the polyolefin may be used. The substrate may also be in the form of a nonwoven fabric or a woven fabric. The substrate may have a single film or a multilayer film structure. For example, the substrate may be a polyethylene monolayer, Polypropylene monolayer, polyethylene / polypropylene double membrane,

Polypropylene / polyethylene / polypropylene triple film, polyethylene / polypropylene / polyethylene triple film, etc. are mentioned. The thickness of the substrate may be 1 kPa to 40 ^' , for example, 1; kPa to 30 ^, 1 ^ 111 to 20 kPa, 5 to 15, and 5 / m to 10. When the thickness of the substrate is within the above range, it is possible to prevent a short circuit between the positive electrode and the negative electrode without increasing the internal resistance of the battery.

The heat resistant porous layer is formed on one side or both sides of the substrate, and may include a polymer.

The polymer may include a structural unit represented by Formula 1 below.

[Formula 1]

In Formula 1, X is a single bond, -CO-, -SO _r , -COO-, -CONR '-(R' is a substituted or unsubstituted C1 to C20 alkyl group, or a substituted or unsubstituted C6 to C30 aryl ),-POR "-(R" is a hydrogen atom, a substituted or unsubstituted C 1 to C20 alkyl group, or a substituted or unsubstituted C6 to C30 aryl group), a substituted or unsubstituted C1 to C20 alkylene group, substituted Or an unsubstituted C2 to C20 alkenylene group, a substituted or unsubstituted C2 to C20 alkynylene group, a substituted or unsubstituted C3 to C20 cycloalkylene group, a substituted or unsubstituted C3 to C20 cycloalkenylene group, a substituted or Unsubstituted C4 to C20 cycloalkynylene group, substituted or unsubstituted C6 to C30 arylene group, substituted or unsubstituted fluorenylene group, substituted or unsubstituted C1 to C20 alkylidene group, substituted or unsubstituted C3 To C20 cycloalkylidene group, substituted or unsubstituted phthalidyl May group, at least one of a substituted or unsubstituted fluorenylidene group, or a -CO-, -SO _r, -COO- and -CONR'- the connection date derived from spiro (spiro) compound contained in the chain. Among them, for example, a single bond, a substituted or unsubstituted C1 to C20 alkylene group, a substituted or unsubstituted C 1 to C20 alkylidene group, a substituted or unsubstituted C3 to C20 cycloalkylidene group, a substituted or unsubstituted A substituted phthalidylidene group, a substituted or unsubstituted fluorenylidene group, -CO-, -S0 _2- , -COO-, -CONR '-(R' is substituted or unsubstituted C1 To C20 alkyl group, or a substituted or unsubstituted C6 to C30 aryl group), and for example, -CO-, -S0 ₂ -or one of the linking groups represented by the following Chemical Formulas 2-1 to 2-3: have.

Equation 2-1]

[Formula 2 ᅳ 2]

[Formula 2-3]

In Chemical Formula 1, Z may be a single bond or an oxygen atom.

In Formula 1, R ¹ represents a hydrogen atom, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C2 to C20 alkynyl group, a substituted or unsubstituted C3 to C20 It may be a cycloalkyl group, a substituted or unsubstituted C3 to C20 cycloalkenyl group, a substituted or unsubstituted C4 to C20 cycloalkynyl group or a substituted or unsubstituted C6 to C30 aryl group. Among them, for example, the substituted or unsubstituted C6 to C30 aryl group may be used in terms of securing excellent heat resistance and oxidation resistance.

In addition, n may be an integer of 3 to 1000, for example, an integer of 5 to 500, an integer of 10 to 450, an integer of 15 to 430, an integer of 50 to 400, an integer of 100 to 400.

The polymer may be a phosphonate backbone or

It may include a structural unit in which the phosphate skeleton and the bisphenol skeleton are connected to each other. According to one embodiment, when forming a heat-resistant porous layer of the polymer of the structure can ensure a separator excellent in flame retardancy, heat resistance and breathability, it is possible to implement a stable lithium secondary battery during battery ignition and battery overheating. Also As the adhesion to the substrate is increased, the life characteristics of the battery according to the repeated layer discharge may also be improved.

The weight average molecular weight (Mw) of the polymer may be 1,000 g / mol to 350,000 g / mol, for example, 5,000 g / mol to 150,000 g / mol. When the weight average molecular weight of the polymer is within the above range, it is possible to secure a separator having more excellent flame retardancy, heat resistance and breathability. The weight average molecular weight is gel permeation

The polystyrene conversion value measured by chromatography (GPC) is shown.

The glass transition degree (Tg) of the polymer may be 100 ^° C to 250 t, for example, 150 ^° C to 220 ^° C. When the glass transition temperature of the polymer is within the above range, it is possible to secure a separator having more excellent flame retardancy, heat resistance and breathability. The polymer may be used alone as a binder of the heat resistant porous layer. The heat-resistant porous layer may have a thickness of 0.01 μΆ to 20 ΙΜ, for example, 1 Ά to 10, 1 to 5. When the thickness of the heat-resistant porous layer is within the above range, it is excellent in flame retardancy, heat resistance and air permeability, thereby suppressing battery internal short circuit and securing a stable separator and suppressing increase in battery internal resistance.

Hereinafter, a separator for a rechargeable lithium battery according to another embodiment is described. The separator for a rechargeable lithium battery according to the present embodiment may include a substrate and a heat resistant porous layer positioned on at least one surface of the substrate, and the heat resistant porous layer may include a crab binder and a second binder different from the first binder. . In this case, the first binder may be the polymer described above. The separator of the present embodiment is different from the separator for a lithium secondary battery according to the above-described embodiment in that it includes a second binder, and since the other components are substantially the same, the second binder will be described here as a core.

The second binder is a compound different from the polymer, specifically

Polyvinylidene fluoride (PVdF), polymethyl methacrylate, polyacrylonitrile, polyvinylpyridone, polyvinylacetate, polyethylene-vinylacetate co-polymer, polyethylene oxide, cellulose acetate, cellulose acetate butyrate ， Cellulose acetate propionate, cyanoethylpullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, Pullulan, carboxymethylcellulose, acrylonitrile-styrene-butadiene copolymers, copolymers thereof or combinations thereof may be used. Among them, for example, polyvinylidene fluoride (PVdF), a copolymer thereof or a combination thereof can be used. Specifically, the polyvinylidene fluoride copolymer may use a copolymer including a vinylidene repeat unit and a nucleus fluoropropylene repeat unit. For example, polyvinylidene fluoride-nucleus fluoropropylene (PVdF-HFP) binary copolymers or other repeating units other than vinylidene repeating units and nuxafluoroflopylene repeating units (e.g., acrylic acid, acid anhydride, etc.) Ternary copolymers containing may be used.

When the polyvinylidene fluoride (PVdF), polyvinylidene fluoride copolymer or a combination thereof is used together with the polymer, it is possible to form a uniform heat-resistant porous layer with higher adhesion to the substrate, thereby More stable

Separator can be secured. In addition, since the electrolyte impregnation property is excellent, the high rate layer discharge characteristic of the battery can be improved.

The polyvinylidene fluoride (PVdF) has a weight average molecular weight of 800,000 g / mol or more _: specifically 1,000,000 g / mol or more, more specifically 1,000,000 to 1,600,000 g / mol, even more specifically 1,000,000 to 1,200,000 g / mol may be used, but is not limited thereto. When the weight average molecular weight of the polyvinylidene fluoride (PVdF) is within the above range, not only the adhesion between the substrate and the heat-resistant porous layer can be further enhanced, but also the adhesion with the electrode can be improved. In addition, the shrinkage of the substrate due to heat can be suppressed, and the short-circuit between the positive electrode and the negative electrode can be prevented, and the solvent can be easily dissolved in a small amount of solvent during formation of the heat-resistant porous layer to facilitate drying of the heat-resistant porous layer. . The polyvinylidene fluoride copolymer may have a weight average molecular weight of 800,000 g / mol or less, specifically, 500,000 g / mol to 800,000 g / mol, but is not limited thereto. Of the polyvinylidene fluoride copolymer

When the weight average molecular weight is within the above range, it is possible to implement a lithium secondary battery having improved electrolyte impregnation property and improved high rate charge / discharge characteristics.

The polyvinylidene fluoride copolymer, but it may include a repeating unit derived from propylene in hex-fluoro-0.1% by weight to 40 parts by weight ^_0/0 with respect to the total of all repeating units, and the like.

The heat-resistant porous layer is formed of both the first binder and the second binder of the polymer If it does, the first binder of the polymer is 20 parts by weight ^_0/0 to 99 weight ^_0/0 with respect to the total amount of the second binder and the first binder of the polymer, specifically, 50 parts by weight ^_0/0 to 99% by weight It may be included as. When the polymer is included in the content range, as well as flame retardancy and heat resistance, the processability at the time of forming the separator and the stability to the electrolyte are excellent, and as the adhesion to the substrate is enhanced, a more stable separator can be secured.

Hereinafter, a separator for a rechargeable lithium battery according to another embodiment is described.

The separator for a rechargeable lithium battery according to the present embodiment may include a substrate and a heat resistant porous layer positioned on at least one surface of the substrate, and the heat resistant porous layer may include a binder and a filler. In this case, the binder may be a mixture of two or more kinds of binders including the aforementioned polymer or the aforementioned polymer. The separator of the present embodiment is different from the separator for a lithium secondary battery according to the above-described embodiments and other embodiments in that it includes a filler, and the other components are substantially the same, and thus, the filler will be described herein.

When the filler is added to the heat resistant porous layer, the shrinkage of the substrate by heat is further increased.

By preventing, short circuit between the positive electrode and the negative electrode can be suppressed, and the performance of the battery can be improved by minimizing the resistance of lithium ions. The filler may include inorganic particles, organic particles, or a combination thereof. The inorganic particles may include A1 ₂ 0 ₃ , Si0 ₂ , B ₂ 0 ₃ , Ga ₂ 0 ₃ , Ti0 ₂ , Sn0 _2, or a combination thereof. It may include, but is not limited thereto.

The organic particles may be particles including an acrylic compound, an imide compound, an amide compound, or a combination thereof, but are not limited thereto. In addition, the organic particles may have a core-shell structure, but are not limited thereto.

The filler may have an average particle diameter of l nm to 2000 nm, for example, lOO nm to lOOOO nm, lOO nm to 500 nm. Moreover, you may mix and use 2 or more types of fillers from which a particle diameter differs. When the average particle diameter of the filler is in the above range, it can be uniformly coated on the substrate when forming a heat-resistant porous insect, can suppress the short circuit between the positive electrode and the negative electrode, and also minimize the resistance of lithium ions to secure the performance of the lithium secondary battery can do. The amount of the filler can comprise from 30 weight% to 90 weight ⁰ /. With respect to the total of the heat resistant porous layer, for example, it may be included as 60 wt% to 90 wt. ⁰ /. When the filler is included in the content range, a short circuit between the positive electrode and the negative electrode

It can suppress and improve battery performance.

Hereinafter, a method of manufacturing a separator for a lithium secondary battery according to another embodiment is described.

The heat-resistant porous insect may be formed by applying a coating composition comprising the polymer and a solvent on at least one side of the substrate and then drying. In this case, the coating composition may further include at least one of the second binder and the filler different from the polymer.

The solvent includes alcohols such as methanol, ethanol and isopropyl alcohol; Ketones such as acetone may be used, but are not limited thereto.

The coating composition may be obtained by mixing 1 to 30% by weight of the polymer and the balance of the solvent, and stirring at 10 ^° C to 40 ^° C for 30 minutes to 5 hours.

The stirring may be performed using a ball mill, a beads mill, a screw mixer, or the like.

A method of applying the coating composition to the substrate may include a dip coating method, a die coating method, a roll coating method, a comma coating method, and the like, but is not limited thereto.

The drying may be performed by a method of drying by hot air, hot air or low humidity, vacuum drying, or irradiation of far infrared rays, electron beams, etc., but is not limited thereto. The drying process may be carried out at a temperature of 60 ^° C to 120 ^° C. When performed in the silver range, it is possible to form a heat resistant porous layer having a smooth surface without requiring a long drying time. ·

Formation of the heat-resistant porous layer on the substrate may be performed by a method such as lamination, coextrusion, etc., in addition to the coating method using the coating composition.

Hereinafter, a lithium secondary battery including the above-described separator will be described with reference to FIG. 1.

1 is an exploded perspective view of a rechargeable lithium battery according to one embodiment. Lithium secondary battery according to an embodiment is described as an example of the square, but the present invention is limited thereto The present invention may be applied to various types of batteries such as lithium polymer batteries and cylindrical batteries.

Referring to FIG. 1, a lithium secondary battery 100 according to an embodiment includes an electrode assembly 40 wound between a positive electrode 10 and a negative electrode 20 via a separator 30, and the electrode

A case 50 in which the assembly 40 is embedded. The positive electrode 10, the negative electrode 20 and the separator 30 are impregnated with an electrolyte (not shown).

The separator 30 is as described above.

The positive electrode 10 may include a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector. The positive electrode active material layer is a positive electrode active material, a binder and

It may optionally include a conductive material.

As the cathode current collector, aluminum (A1), nickel (Ni), or the like may be used, but the present invention is not limited thereto.

As the cathode active material, a compound capable of reversible intercalation and deintercalation of lithium may be used. Specifically, at least one of cobalt, manganese, nickel, aluminum, iron or a combination of metal and lithium composite oxides or phosphorus oxides may be used. More specifically, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, or a combination thereof may be used.

The binder not only adheres the positive electrode active material particles to each other well but also serves to adhere the positive electrode active material to the positive electrode current collector.

Polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose,

Diacetyl cellulose, polyvinylchloride, carboxylated polyvinylchloride, polyvinylfluoride, ethylene oxide containing polymer, polyvinylpyridone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene , Polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon and the like, but are not limited thereto. These may be used alone or in combination of two or more thereof.

The conductive material imparts conductivity to the electrode, and examples thereof include natural graphite, artificial graphite, carbon black, carbon fiber, metal powder, and metal fiber, but are not limited thereto. These can be used individually or in mixture of 2 or more types. The metal ts i

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The electrolyte solution contains an organic solvent and a lithium salt.

The organic solvent serves as a medium through which ions involved in the electrochemical reaction of the battery can move. Specific examples thereof may be selected from carbonate solvents, ester solvents, ether solvents, ketone solvents, alcohol solvents and aprotic solvents.

Examples of the carbonate solvent include dimethyl carbonate (DMC) and diethyl

Carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), ethylmethyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC ), And the like. Specifically, when a mixture of the chain carbonate compound and the cyclic carbonate compound is used, the dielectric constant may be increased and the solvent may be prepared with a low viscosity. At this time

The carbonate compound and the chain carbonate compound are in a volume ratio of 1: 1 to 1: 9.

It can be used in combination.

Examples of the ester solvents include methyl acetate, ethyl acetate, η-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, γ-butyrolactone, decanolide, valerolactone and memeth Melononolactone, caprolactone, and the like. Examples of the ether solvent,

Dibutyl ether, tetraglyme, diglyme, dimethoxyethane, 2-methyltetrahydrofuran, tetrahydrofuran and the like ^. have. Examples of the ketone solvent include cyclonucleanone and the like, and examples of the alcohol solvent include ethyl alcohol and isopropyl alcohol. The organic solvents may be used alone or in combination of two or more thereof, and the mixing ratio in the case of mixing two or more kinds may be appropriately adjusted according to the desired battery performance.

The lithium salt is a substance that dissolves in an organic solvent and acts as a source of lithium ions in the battery to enable operation of a basic lithium secondary battery and to promote the migration of lithium silver between the positive electrode and the negative electrode.

Examples of the lithium salt, LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiN (S0 ₃ C ₂ F ₅ ) ₂ , LiN (CF ₃ S0 ₂ ) ₂ , L1C4F9SO3, L1CIO ₄ , LiA10 ₂ , LiAlCl ₄ , LiN (C _x F _{2x +} , SO ₂ ) (C _y F _{2y +} , SO ₂ ) (x and y are natural numbers), LiCl, Lil, LiB (C ₂ 0 ₄ ) ₂ or a combination thereof. The concentration of the lithium salt can be used within the range of 0.1M to 2.0M ᅳ When the concentration of the lithium salt is within the above range, since the electrolyte has an appropriate conductivity and viscosity can exhibit excellent electrolyte performance, lithium ions can move effectively. . The lithium secondary battery including the above-described separator can be operated at a high voltage of 4.35V or more, thereby realizing a high capacity lithium secondary battery without deterioration of life characteristics. Hereinafter, specific embodiments of the present invention will be presented. However, the embodiments described below are only used to specifically illustrate or describe the present invention, and the present invention should not be limited thereto. In addition, the contents not described herein are those that can be inferred technically by those skilled in the art will not be described. Polymer synthesis

Synthesis Example 1

33.0 g (140 mmol) of bisphenol A and 35.8 g (350 mmol) of triethylamine

After addition to 210 mL methylene chloride, it was cooled to 0 ^° C. Then 28.1 g

A solution of phenylphosphonic dichloride in 15 mL of methylene chloride was slowly added for 1 hour and then reacted at room temperature for 4 hours. The reaction solution was washed several times with distilled water and dilute HC1 solution. 80 ^° C Washed Polymer

After drying for 48 hours in a vacuum oven, a polymer including a structural unit represented by the following Chemical Formula 3-1 was synthesized. The weight average molecular weight (Mw) of the synthesized polymer was 145,000 g / mol.

-One]

Synthesis Example 2

In Synthesis Example 1, 35.0 g (140 mmol) of bisphenol β was substituted for 33.0 g (140 mmol) of bisphenol A. Synthesis was carried out in the same manner as in Synthesis Example 1, except that the polymer containing the structural unit represented by the following Formula 3-2 was synthesized. Of the synthesized polymer

The weight average molecular weight (Mw) was 101,000 g / mol.

-2]

Synthesis Example 3

Synthesis Example 1 was synthesized in the same manner as in Synthesis Example 1, except that 30.0 g (140 mmol) of 4,4-dihydroxy benzophenone was used instead of 33.0 g (140 mmol) of Bisphenol A. A polymer comprising structural units was synthesized. The weight average molecular weight (Mw) of the synthesized polymer was 110,000 g / mol.

-3]

Synthesis Example 4

Synthesis was carried out in the same manner as in Synthesis Example 1 except for using biphenol 26.3 g (140 mmol) instead of 33.0 g (140 mmol) of bisphenol A in Synthesis Example 1, to obtain a polymer including a structural unit represented by the following Chemical Formula 3-4: Synthesized. Of the synthesized polymer

The weight average molecular weight (Mw) was 130,000 g / mol.

-4]

Synthesis Example 5

Synthesis Example 1 was synthesized in the same manner as in Synthesis Example 1, except that 37.5 g (140 mmol) of bisphenol Z was used instead of 33.0 g (140 mmol) of Bisphenol A. A polymer containing the structural unit represented was synthesized. Of the synthesized polymer

The weight average molecular weight (Mw) was 125,000 g / mol.

-5]

Synthesis Example 6

Synthesis was carried out in the same manner as in Synthesis Example 1, except that 44.5 g (140 mmol) of phenolphthalein was used instead of 33.0 g (140 mmol) of bisphenol A in Synthesis Example 1 to synthesize a polymer including a structural unit represented by Formula 3-6. It was. The weight average molecular weight (Mw) of the synthesized polymer was 150,000 g / mol.

3-6]

Synthesis Example 7

9,9 '-bis (Φ · instead of 33.0 g (l ^{4 0} mmol) of bisphenol A in Synthesis Example 1

Except that 49.0 g (140 mmol) of hydroxyphenyl) fluorene was used, it synthesize | combined by the same method as the synthesis example 1, and synthesize | combined the polymer containing the structural unit represented by following formula (3-7). The weight average molecular weight (Mw) of the synthesized polymer was 135,000 g / mol. [Formula 3-7]

Synthesis Example 8

38.0 g (140 mmol) bisphenol Z and 35.8 g (350 mmol) triethylamine

After addition to 210 mL methylene chloride, it was cooled to 0 ^° C. Then, a solution of 29.53 g of phenyl phosphorodichloridate dissolved in 15 mL of methylene chloride was slowly added for 1 hour, and then reacted at room temperature for 4 hours.

The reaction solution was washed several times with diluted HC1 solution and distilled water. The washed polymer was dried in a vacuum oven at 80 ^° C. for 48 hours to synthesize a polymer including a structural unit represented by the following Chemical Formula 3-8. Of the synthesized polymer

The weight average molecular weight (Mw) was 123,000 g / mol.

-8]

Synthesis Example 9

Synthesis Example 8 Synthesis was performed in the same manner as in Synthesis Example 8, except that 44.5 g (140 mmol) of phenolphthalein was used instead of 38.0 g (140 mmol) of bisphenol Z to synthesize a polymer including a structural unit represented by Chemical Formula 3-9. It was. Of the synthesized polymer

The weight average molecular weight (Mw) was 147,000 g / mol. Formula 3-9]

Synthesis Example 10

Synthesis Example 8 Synthesis was performed in the same manner as in Synthesis Example 8, except that 33.0 g (140 mmol) of Bisphenol A was used instead of 38.0 g (140 mmol) of Bisphenol Z, thereby obtaining a polymer including a structural unit represented by the following Formula 3-10: Synthesized. The weight average molecular weight (Mw) of the synthesized polymer was 142,000 g / mol.

-10]

Synthesis Example 11

4,4'-sulfonyldiphenol instead of 38.0 g (140 mmol) of bisphenol Z in Synthesis Example 8

Synthesis was carried out in the same manner as in Synthesis Example 8 except that 35.0 g (140 mmol) was used to synthesize a polymer including a structural unit represented by Chemical Formula 3-1 1 below. The weight average molecular weight (Mw) of the synthesized polymer was 102,000 g / mol.

-11]

Synthesis Example 12

4,4'-dihydric benzophenone instead of 38.0 g (140 mmol) of bisphenol Z in Synthesis Example 8 Except for using 30.0g (140mmol) was synthesized in the same manner as in Synthesis Example 8, to synthesize a polymer containing a structural unit represented by the following formula (3-12). The weight average molecular weight (Mw) of the synthesized polymer was 105,000 g / mol.

-12]

Synthesis Example 13

A polymer comprising a structural unit represented by the following Chemical Formula 3-13 was synthesized in the same manner as in Synthesis Example 8 except for using 26.3 g (140 mmol) of biphenol instead of 38.0 g (140 mmol) of bisphenol Z in Synthesis Example 8. Synthesized. The weight average molecular weight (Mw) of the synthesized polymer was 126,000 g / mol.

-13]

Synthesis Example 14

Synthesis Example 8 was synthesized in the same manner as in Synthesis Example 8, except that 49.0 g (140 mmol) of 9,9′-bis (4-hydroxyphenyl) fluorene was used instead of 38.0 g (140 mmol) of bisphenol Z. A polymer comprising the structural unit represented by 3-14 was synthesized. The weight average molecular weight (Mw) of the synthesized polymer was 132,000 g / mol. [Formula 3-14]

Separator manufacturer

Example 1

A polymer solution was prepared by dissolving the polymer prepared in Synthesis Example 1 at 10 weight ⁰ /. In tetrahydrofuran (THF). A1 ₂ 0 ₃ (LS235A, Nippon Light Metal Co., Ltd.) was added to acetone. An inorganic dispersion was prepared by adding 25 weight ⁰ / ^° and milling and dispersing at 25 ^° C. for 3 hours using a bead mill. The polymer solution and the inorganic dispersion prepared above were mixed with a mixed solvent of Ν, Ν-dimethylacetamide (DMAc) and THF so as to have a weight ratio of 2.5: 5: 2.5, respectively, and stirred at 25 ^° C. with a power mixer for 1 hour. The coating composition was prepared.

The prepared coating composition was coated on both sides of a polyethylene single layer substrate film having a thickness of 9 by a dip coating method, respectively, and then dried at 1 H C for 1 minute to prepare a separator.

Example 2

A separator was prepared in the same manner as in Example 1, except that the coating composition was prepared using the plymer prepared in Synthesis Example 2 instead of Synthesis Example 1. Example 3

A separator was prepared in the same manner as in Example 1, except that the coating composition was manufactured using the polymer prepared in Synthesis Example 3 instead of Synthesis Example 1. Example 4

A separator was prepared in the same manner as in Example 1, except that the coating composition was prepared using the polymer prepared in Synthesis Example 4 instead of Synthesis Example 1. Example 5 A separator was prepared in the same manner as in Example 1, except that the coating composition was prepared using the polymer prepared in Synthesis Example 5 instead of Synthesis Example 1. Example 6

A separator was prepared in the same manner as in Example 1, except that the coating composition was prepared using the polymer prepared in Synthesis Example 6 instead of Synthesis Example 1. Example 7

A separator was prepared in the same manner as in Example 1, except that the coating composition was prepared using the polymer prepared in Synthesis Example 7 instead of Synthesis Example 1. Example 8

A separator was prepared in the same manner as in Example 1, except that the coating composition was prepared using the polymer prepared in Synthesis Example 8 instead of Synthesis Example 1. Example 9

A separator was prepared in the same manner as in Example 1, except that the coating composition was prepared using the polymer prepared in Synthesis Example 9 instead of Synthesis Example 1. Example 10

A separator was prepared in the same manner as in Example 1, except that the coating composition was prepared using the polymer prepared in Synthesis Example 10 instead of Synthesis Example 1. Example 11

A separator was prepared in the same manner as in Example 1, except that the coating composition was manufactured using the polymer prepared in Synthesis Example 1 1 instead of Synthesis Example 1. Example 12

A separator was prepared in the same manner as in Example 1, except that the coating composition was prepared using the plymer prepared in Synthesis Example 12 instead of Synthesis Example 1. Example 13

A separator was prepared in the same manner as in Example 1, except that the coating composition was prepared using the polymer prepared in Synthesis Example 13 instead of Synthesis Example 1. Example 14

A separator was prepared in the same manner as in Example 1, except that the coating composition was manufactured using the polymer prepared in Synthesis Example 14 instead of Synthesis Example 1. Comparative Example 1 A separator was prepared in the same manner as in Example 1, except that poly (butyl acrylate -CO- methylmethacrylate -co-vinylacetate) was used instead of the polymer prepared in Synthesis Example 1. Lithium Secondary Battery

LiCo0 ₂ , polyvinylidene fluoride and carbon black were added to an N-methylpyrrolidone (NMP) solvent in a weight ratio of 96: 2: 2 to prepare a slurry. The slurry was applied to an aluminum (A1) thin film, dried, and rolled to prepare a positive electrode.

Absolutely, polyvinylidene fluoride and carbon black were added to an N-methylpyrrolidone (NMP) solvent in a weight ratio of 98: 1: 1 to prepare a slurry. The slurry was applied to copper foil, dried and rolled to prepare a negative electrode.

The electrolyte solution was prepared by adding 1.15 M of LiPF ₆ to a mixed solvent in which ethylene carbonate (EC), ethylmethyl carbonate (EMC) and diethyl carbonate (DEC) were mixed at a volume ratio of 3: 5: 2.

A lithium secondary battery was manufactured using the positive electrode, the negative electrode, and the electrolyte solution prepared above, and the separators prepared in Examples 1 to 14 and Comparative Example 1. evaluation

Evaluation 1: Physical Properties of the Binder

Weight average molecular weight (Mw) and glass relative to the polymer used in the preparation of the separators of Examples 1 to 14 and the poly (butylacrylate _ _C0 -methyl methacrylate ᅳ _co _ vinyl acetate) used in the preparation of the separator of Comparative Example 1 Transition temperature (Tg) and flame retardancy were respectively measured by the following method, and the results are shown in Table 1 below.

(1) Weight average molecular weight (Mw): It was shown by the polystyrene conversion value measured by the gel permeation chromatography (GPC).

(2) Glass transition temperature (Tg): Measured by differential scanning calorimetry (DSC).

(3) Flame retardancy (1/8 "): Measured according to UL94 VB flame retardant regulations.

Evaluation 2: Flame Retardant of Separator

For the separators prepared in Examples 1 to 14 and Comparative Example 1, a specimen was prepared in the following manner to evaluate the flame retardancy according to the UL94 VB flame retardant regulations. The 10 cm X 50 cm separators prepared in Examples 1 to 14 and Comparative Example 1 were folded to 10 cm X 2 cm, and then the upper and lower portions were fixed to prepare specimens. Flame retardant ratings were determined based on specimen burn time in accordance with UL94 VB.

The results are shown in Table 1 below.

Table 1

Through Table 1, it can be seen that the polymer used as the binder in Examples 1 to 14 is excellent in both flame retardancy and heat resistance compared to the binder used in Comparative Example 1, accordingly, using the polymer alone as a binder heat-resistant porous layer It can be seen that the separator formed with both excellent flame retardancy and heat resistance.

Evaluation 3: breathability and heat resistance of the separator For the separators prepared in Examples 1 to 14 and Comparative Example 1, the air permeability and heat resistance were measured by the following methods, respectively, and the results are shown in Table 2 below. The air permeability of the air permeation time was measured by OO01 air by using EG01-55-lMR (Asahi Seiko / tt), and the heat resistance measured the shrinkage rate after each separator was placed in a 200 ^° C. oven for 30 minutes.

Table 2

Through the Table 2, the separator of the embodiment to form a heat-resistant porous layer by using the polymer alone as a bar more Examples 1 to 14 it can be seen that excellent air permeability and is excellent in heat resistance compared to Comparative Example 1, ^i. Accordingly, the separator according to one embodiment may contribute to the stability and performance of the secondary battery. Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto and is defined in the following claims. Various modifications and improvements of those skilled in the art using the basic concepts of the present invention are also within the scope of the present invention.

[Explanation of code]

100: lithium secondary battery

10: anode

20: cathode

30: separator

40: electrode assembly

50: case

Claims

[Claim 1] A separator for a lithium secondary battery comprising a base material and a heat-resistant porous layer comprising a polymer located on at least one side of the base material and having a structural unit represented by the following general formula (1).

[Formula 1]

In Chemical Formula 1,

X is a single bond, -CO-, -S0 _2- , -COO-, -CONR'- (R 'is a substituted or unsubstituted C1 to C20 alkyl group, or a substituted or unsubstituted C6 to C30 aryl group),- POR "-(R" is a hydrogen atom, a substituted or unsubstituted C1 to C20 alkyl group, or a substituted or unsubstituted C6 to C30 aryl group), a substituted or unsubstituted C1 to C20 alkylene group, a substituted or unsubstituted C2 To C20 alkenylene group, substituted or unsubstituted C2 to C20 alkynylene group, substituted or unsubstituted C3 to C20 cycloalkylene group, substituted or unsubstituted C3 to C20 cycloalkenylene group, substituted or unsubstituted C4 to C20 cycloalkynylene group, substituted or unsubstituted C6 to C30 arylene group, substituted or unsubstituted fluorenylene group, substituted or unsubstituted C1 to C20 alkylidene group, substituted or unsubstituted C3 to C20 cycloalkylie Den groups, substituted or unsubstituted phthalidylidene groups, substituted or unsubstituted And, spiro linkage group derived from a (spiro) compound contained in the -COO- and -CONR'- increase at least one chain, - a fluorenylidene group, or -CO-, -S0 ₂

Z is a single bond or an oxygen atom,

R ¹ is a hydrogen atom, substituted or unsubstituted C1 to C20 alkyl group, substituted or unsubstituted C2 to C20 alkenyl group, substituted or unsubstituted C2 to C20 alkynyl group, substituted or unsubstituted C3 to C20 cycloalkyl group, substituted Or an unsubstituted C3 to C20 cycloalkenyl group, a substituted or unsubstituted C4 to C20 cycloalkynyl group, or a substituted or unsubstituted C6 to C30 aryl group, n is an integer of 3 to 1000.

[Claim 2]

The method of claim 1,

X in Chemical Formula 1 is a single bond, a substituted or unsubstituted C1 to C20 alkylene group, -CO-, -S0 _2- , -COO-, -CONR '-(R' is substituted or unsubstituted C1 to C20 An alkyl group or a substituted or unsubstituted C6 to C30 aryl group, or a separator for a lithium secondary battery, which is one of the linking groups represented by the following Chemical Formulas 2-1 to 2-3.

-One]

[Claim 3]

The method of claim 1,

A weight average molecular weight (Mw) of the polymer is a separator for a lithium secondary battery is 1,000 g / mol to 350,000 g / mol.

[Claim 4]

The method of claim 1,

The glass transition temperature (Tg) of the polymer is 110 ^° C to 250 V separator for lithium secondary battery.

[Claim 5]

The method of claim 1,

The heat-resistant porous layer is made of polyvinylidene fluoride (PVdF),

Polymethyl methacrylate, polyacrylonitrile, polyvinylpyridone, Polyvinylacetate, polyethylene-vinylacetate copolymer, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol,

A separator for a lithium secondary battery, further comprising a binder of cyanoethyl salose, cyanoethyl sucrose, pullulan, carboxymethyl cellulose, acrylonitrile-styrene-butadiene copolymer, copolymers thereof, or a combination thereof.

[Claim 6]

The method of claim 5,

The polymer is a lithium secondary battery separator comprising from 20% to 99% by weight relative to the total amount of the polymer and the binder.

[Claim 7]

According to claim 1,

The heat-resistant porous layer is a separator for a lithium secondary battery further comprises a filler containing inorganic particles, organic particles or a combination thereof.

[Claim 8]

The method of claim 7, wherein

The inorganic particles include A1 ₂ 0 ₃ , Si0 ₂ , B ₂ 0 ₃ , Ga ₂ 0 ₃ , Ti0 ₂ , Sn0 ₂ or a combination thereof,

The organic particles may include an acrylic compound, an imide compound, an amide compound, or a combination thereof.

Separators for lithium secondary batteries.

[Claim 9]

The separator according to any one of claims 1 to _8.

. Lithium secondary battery comprising a.

[Claim 10]

According to claim 19,

The lithium secondary battery is a lithium secondary battery operated at a voltage of 4.35V or more.