KR101686597B1 - Separator for electrochemical cell and method for preparing the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an amorphous high performance plastics or amorphous engineering plastics polymer compounds (hereinafter collectively referred to as 'amorphous polymer compounds' The porous separator has a high air permeability and an excellent adhesive strength while maintaining excellent mechanical strength. Therefore, the porous separator is very suitable for use as a separator for electrochemical devices, and has a simple manufacturing method.

Description

Separator for electrochemical device and method for manufacturing the same

The present invention relates to a separator for an electrochemical device and a method of manufacturing the separator. More specifically, the present invention relates to a separator for an electrochemical device, and more particularly to an amorphous high performance plastics or an amorphous engineering plastics high molecular compound (hereinafter collectively referred to as an ' (Hereinafter, referred to as " porous substrate ") and having an adhesive layer formed on the porous substrate, and having excellent mechanical strength, air permeability and adhesive strength, and a method for producing the same.

As the demand for batteries as an energy source increases, interest in electrochemical devices capable of charging and discharging is increasing, and in particular, demand and interest in lithium secondary batteries are increasing.

The lithium secondary battery includes an electrode assembly composed of an anode, a separator, and a cathode. The separator provides a passage through which lithium ions can actively move as a polymer membrane and prevents direct contact between the anode and the cathode. Since the mechanical strength of the separator is also related to the safety of the battery from an external force, many kinds of materials such as high-performance plastics and engineering plastics have been studied as separator materials.

In particular, amorphous polymer compounds such as polyamide-imide resins and polyetherimide resins are attracting attention as heat-resistant resins having excellent heat resistance, electrical characteristics, adhesion, moisture resistance and workability in the field of electronic materials. However, although these resins have excellent properties as described above, there is a problem that the flexibility and flexibility of the cured film are insufficient because of poor rigidity of the resin structure and adhesion to the base material and low plasticity.

In order to solve these problems, Japanese Patent Application Laid-Open Nos. 6-89150 and 7-5729 disclose a method for producing a resin composition which is obtained by adding plasticity to a resin using carbonic acid-terminated acrylonitrile butadiene, Amide acrylonitrile butadiene copolymer to impart plasticity to the polymer skeleton to improve the adhesiveness and flexibility of the film. However, the use of the amide acrylonitrile-butadiene copolymer as a separation membrane is insufficient in terms of air permeability and adhesion, and there is still a need for improvement do.

1. Japanese Patent Application Laid-Open No. 6-89150 2. Japanese Patent Application Laid-Open No. 7-5729

The present invention provides a porous separator for an electrochemical device of high heat-resistant engineering plastic material having excellent strength and adequate air permeability and also excellent in adhesion and a method for producing the same.

According to one aspect of the present invention, there is provided a porous substrate comprising an amorphous polymer compound; And an adhesive layer formed on the porous substrate.

The amorphous polymer compound may be a polyetherimide having a repeating unit represented by the following Formula 1:

[Chemical Formula 1]

Wherein T is -O- or a formula -OZO- group wherein the divalent bond of the -O- or -OZO- group is 3,3 ', 3,4', 4,3 'or 4,4 'position, and Z includes divalent radicals of the formula:

,

,

의 2가 라디칼을 포함하나, 이에 한정되지 않고, X is

Lt; / RTI > include, but are not limited to,

y is an integer from 1 to 5,

q is 0 or 1,

의 2가 라디칼을 포함하나, 이에 한정되지 않고, Q는

을 포함하나, 이에 한정되지 않고, y는 1 내지 5의 정수이다. R is an aromatic hydrocarbon radical having 6 to 20 carbon atoms; An alkylene radical having 2 to 20 carbon atoms, a cycloalkylene radical having 3 to 20 carbon atoms; And equation

Include, but are not limited to, < RTI ID = 0.0 >

But is not limited thereto, and y is an integer of 1 to 5.

The amorphous polymer compound may be a polyamide-imide having a repeating unit represented by the following Formula 2:

(2)

의 2가 라디칼을 포함하나, 이에 한정되지 않고, Wherein R is an aromatic hydrocarbon radical having from 6 to 20 carbon atoms; An alkylene radical having 2 to 20 carbon atoms, a cycloalkylene radical having 3 to 20 carbon atoms; And equation

Lt; / RTI > include, but are not limited to,

을 포함하나, 이에 한정되지 않고, Q is

But are not limited to,

y is an integer from 1 to 5,

and n is an integer of 50 to 1000.

The porous substrate may have a thickness of 1 to 100 占 퐉 or 5 to 50 占 퐉.

The porous substrate may have pores having a long diameter in the range of 0.01 to 10 [mu] m.

The porous substrate may have an air permeability ranging from 100 sec / 100cc to 5000 sec / 100cc.

The adhesive layer may be formed of a copolymer of polyvinylidene fluoride (PVDF), polyhexafluoropropylene-polyvinylidene fluoride (P (VdF / HFP)), poly (vinyl acetate), polyvinyl alcohol, polyethylene oxide , Polyvinyl pyrrolidone, alkylated polyethylene oxide, polyvinyl ether, poly (methyl methacrylate), poly (ethyl acrylate), polytetrafluoroethylene, polyvinyl chloride, polyacrylonitrile, polyvinylpyridine And a styrene-butadiene rubber.

The thickness of the adhesive layer may be 0.5 to 10 mu m.

According to an aspect of the present invention, there is provided an electrochemical device comprising an anode, a cathode, a separator, and an electrolyte, wherein the separator is the separator for the electrochemical device.

The electrochemical device may be a lithium secondary battery.

According to an aspect of the present invention, there is provided a process for preparing a polymer solution, comprising the steps of: (S1) dissolving an amorphous polymer compound, an adhesive layer-forming compound and a pore-forming agent in a solvent to obtain a polymer solution; (S2) applying a polymer solution on the support such that the adhesive layer-forming compound in the polymer solution is phase-separated toward the surface; (S3) drying the polymer solution applied on the support to obtain a film; And (S4) separating the film from the support and then dipping the film in water to elute and remove the pore-forming agent to form pores.

The polymer solution may contain 1 to 20 parts by weight of an amorphous polymer compound, 1 to 20 parts by weight of an adhesive layer-forming compound, 1 to 20 parts by weight of a pore-forming agent, and a residual solvent, based on 100 parts by weight of the solution. For example, 10 parts by weight of the amorphous polymer compound, 2 parts by weight of the adhesive layer-forming compound, 1 part by weight of the pore-forming agent, and a residual amount of the solvent.

The pore-forming agent may be polyvinylpyrrolidone, polyvinyl alcohol, polyacrylic acid, or a mixture of two or more selected from them.

The step (S2) may be carried out at a temperature of 20 to 120 DEG C and a relative humidity of 20 to 80%.

The porous separator obtained according to the present invention is highly suitable for use as a separator for electrochemical devices because it has high air permeability and adhesion while maintaining excellent strength.

Further, since the amorphous polymer compound, the adhesive layer-forming compound and the pore-forming agent are mixed together in a solvent and then processed, they are advantageously easily produced.

1 is a photograph of the separation membrane adhesive layer prepared according to Example 1, magnified 500 times.
FIG. 2 is a photograph of the pore formed in the separation membrane produced according to Example 2, magnified 5000 times.
FIG. 3 is a photograph of the surface of the separation membrane prepared according to Example 3, in which the surface (air side) not exposed to the support is enlarged 5,000 times.
Fig. 4 is a photograph of the separation membrane produced according to Example 3, in which the surface (glass surface) of the both surfaces of the separation membrane was brought into contact with the support by 5,000 times magnification.
5 is a graph obtained in an adhesion test of a separator prepared according to Example 3. Fig.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may appropriately define the concept of the term in order to best describe its invention It should be construed as meaning and concept consistent with the technical idea of the present invention.

In addition, the embodiments described in the present specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, various equivalents It should be understood that water and variations may be present.

The separation membrane according to the present invention is a porous separation membrane based on an amorphous polymer compound and is characterized in that an adhesive layer is formed on a substrate.

Examples of the amorphous polymer compound include, but are not limited to, polyetherimide and polyamide-imide.

The polyether imide is preferably a compound having a repeating unit represented by the following formula (1): < EMI ID =

[Chemical Formula 1]

Wherein T is a group of -O- or a formula -OZO- wherein the divalent bond of the -O- or -OZO- group is 3,3 ', 3,4', 4,3 ' Or 4,4 'position, and Z includes divalent radicals of the formula:

,

의 2가 라디칼을 포함하나, 이에 한정되지 않고, y는 1 내지 5의 정수이고, q는 0 또는 1이며, X is

But is not limited thereto, y is an integer of 1 to 5, q is 0 or 1,

의 2가 라디칼을 포함하나, 이에 한정되지 않고, Q는

을 포함하나, 이에 한정되지 않고, y는 1 내지 5의 정수이다. R is an aromatic hydrocarbon radical having 6 to 20 carbon atoms; An alkylene radical having 2 to 20 carbon atoms, a cycloalkylene radical having 3 to 20 carbon atoms; And equation

Include, but are not limited to, < RTI ID = 0.0 >

But is not limited thereto, and y is an integer of 1 to 5.

As the polyetherimide, a commercially available product such as Ultem (registered trademark, General Electric Plastics) can be used.

The polyamide-imide is preferably a compound having a repeating unit represented by the following formula (2)

(2)

의 2가 라디칼을 포함하나, 이에 한정되지 않고, Wherein R is an aromatic hydrocarbon radical having from 6 to 20 carbon atoms; An alkylene radical having 2 to 20 carbon atoms, a cycloalkylene radical having 3 to 20 carbon atoms; And equation

Lt; / RTI > include, but are not limited to,

을 포함하나, 이에 한정되지 않고, y는 1 내지 5의 정수이고, Q is

But is not limited thereto, y is an integer of 1 to 5,

and n is an integer of 50 to 1000.

Alternatively, a commercially available product having repeating units for polyamide-imide may be used (here, n is a positive integer):

According to the present invention, the porous substrate made of the amorphous polymer compound has a thickness of 1 to 100 占 퐉 or 5 to 50 占 퐉.

The porous substrate may have a long diameter (longest diameter) in the range of 0.01 to 10 占 퐉 or 0.1 to 5 占 퐉.

Also, the porous substrate may have an air permeability ranging from 100 to 10000 sec / 100 cc, 100 to 5000 sec / 100 cc or 500 to 5000 sec / 100 cc.

Also, the porous substrate may have a porosity ranging from 10 to 50% or from 20 to 30%.

According to the present invention, an adhesive layer is formed on one surface or both surfaces of a porous substrate made of an amorphous polymer compound. The compound forming the adhesive layer is not particularly limited as long as it is a compound that does not inhibit subsequent phase separation. Specific examples thereof include polyvinylidene fluoride (PVDF), polyhexafluoropropylene-polyvinylidene fluoride (Vinyl acetate), polyvinyl alcohol, polyethylene oxide, polyvinyl pyrrolidone, alkylated polyethylene oxide, polyvinyl ether, poly (methyl methacrylate), poly (ethyl Acrylate), polytetrafluoroethylene, polyvinyl chloride, polyacrylonitrile, polyvinylpyridine or styrene-butadiene rubber. The thickness of the adhesive layer formed by the adhesive layer-forming compound is preferably 0.5 to 10 mu m. If the thickness of the adhesive layer is too thin, it is difficult to provide a predetermined bonding force. On the contrary, if the thickness is too large, the movement of lithium ions may be disturbed and the internal resistance of the battery and the rate characteristic may be deteriorated.

The separation membrane for an electrochemical device according to the present invention as described above can be produced by the following method.

That is, the separation membrane for an electrochemical device according to the present invention comprises the steps of (S1) dissolving an amorphous polymer compound, an adhesive layer-forming compound and a pore-forming agent in a solvent to obtain a polymer solution, (S2) Applying the polymer solution on the support so as to be phase separated toward the surface; (S3) drying the polymer solution on a support to obtain a film; And (S4) separating the film from the support and then dipping the film in water to elute and remove the pore-forming agent to form pores.

The step (S1) of the method for producing a separation membrane for an electrochemical device according to the present invention is a step of obtaining a polymer solution.

According to the present invention, the amorphous polymer compound is used in an amount of 1 to 20 parts by weight or 5 to 15 parts by weight based on 100 parts by weight of the solution. If the content of the amorphous polymer compound is less than 1 part by weight, the viscosity of the polymer solution tends to be insufficient, and the strength and physical properties of the porous film tend to decrease. When the amount of the amorphous polymer compound is more than 20 parts by weight, the viscosity becomes too strong.

The adhesive layer-forming compound is used in an amount of 1 to 20 parts by weight or in an amount of 2 to 10 parts by weight based on 100 parts by weight of the solution. When the content of the adhesive layer-forming compound is less than 1 part by weight, the adhesive strength of the adhesive layer becomes excessively weak. When the content of the adhesive layer-forming compound is more than 20 parts by weight, smooth movement of lithium ions is inhibited.

As the pore-forming agent, polyvinylpyrrolidone, polyvinyl alcohol, polyacrylic acid, or a mixture of two or more selected from them may be used, but the present invention is not limited thereto. The content of the pore-forming agent is 1 to 20 parts by weight or 2 to 10 parts by weight based on 100 parts by weight of the solution. If the content of the pore-forming agent is less than the lower limit value, it is difficult to produce a porous film because the network structure is weak. If the content of the pore-forming agent is larger than the upper limit value, porosity of the porous film is not sufficiently formed, making it difficult to use as a separator for electrochemical devices.

The solvent preferred for use in the present invention is not particularly limited as long as it enables precipitation or gelation of the adhesive layer-forming compound, but N-methyl-2-pyrrolidone (NMP), dimethyl phthalate, acetone acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, cyclohexane, water or a mixture thereof can be used, and N-methylpiperazine Rollidon is particularly preferred.

Various additives such as an antioxidant, an ultraviolet absorber, an anti-blocking agent, a pigment, a dye and an inorganic filler may be added to the polymer solution according to the present invention within a range not impairing the effect of the present invention.

The step (S2) of the present invention is a step of applying the polymer solution onto the support so that the adhesive layer-forming compound in the polymer solution is phase-separated toward the surface.

According to the present invention, the support on which the polymer solution containing the amorphous polymer compound is cast is generally made of a material such as glass, stainless steel, aluminum, copper alloy, PET sheet or the like.

According to the present invention, a conventional coating method known in the art can be used for applying the polymer solution to the support. For example, a solution casting method, a dip coating method, a die coating method, Various methods such as a roll coating method, a comma coating method, a doctor blade method, or a mixing method thereof can be used. For example, the polymer solution may be poured into a supporter and stored in an oven at 100 to 110 ° C so that the polymer solution is spread widely, and then formed into a film having a desired thickness using a doctor blade. A more preferable method of applying the polymer solution to the support is the solution casting method.

In order to phase-separate the adhesive layer-forming compound in the polymer solution toward the surface, the polymer solution is applied on the support at a constant temperature, humidity or nonsolvent condition. The characteristics of the separator are determined according to certain conditions used for phase separation, and the preferred phase separation conditions in the present invention are relative humidity of 40% or more at 60 to 80 ° C. Phase separation by moisture, which is a non-solvent for phase separation, is adopted, but other solvents acting as a non-solvent such as acetone, methanol, ethanol and the like can be adopted for the polymer. The phase separation of the present invention can induce phase separation when only a suitable humidity is used to utilize moisture. By the phase separation, the adhesive layer-forming compound aggregates on the surface side while forming a polymer or a bulk to form an adhesive layer.

The step (S3) of the method for producing a separation membrane for an electrochemical device according to the present invention is a step of drying the polymer solution on a support to obtain a film. As a drying method, a method commonly used in the art can be used.

In the step (S4) of the method for producing a separation membrane for an electrochemical device according to the present invention, the film is peeled from a support and then immersed in water to elute and remove the pore-forming agent to form pores. Pore formers can be removed from water because they are well soluble in water. At this time, if the temperature of the water is increased or a co-solvent such as propanol or ethanol is used, the pore forming agent can be more effectively removed. As a result, the separation membrane for an electrochemical device according to the present invention is obtained in the form of a porous film.

If necessary, the obtained separation membrane may be immersed in water to perform a post-treatment for removing the residual solvent contained in the separation membrane.

The manufacturing method of the present invention may add other processes or modify some processes within the scope of not damaging the effects of the invention, and these should be construed as being included in the scope of the present invention.

According to the present invention, an electrode assembly used in an electrochemical device can be manufactured by laminating the thus-produced film between a cathode and an anode to use as a separator. The electrochemical device includes all devices that perform an electrochemical reaction, and specific examples include capacitors such as all kinds of primary cells, secondary cells, fuel cells, solar cells, or super-capacitor devices. Particularly, a lithium secondary battery including a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery among the above secondary batteries is preferable.

The positive electrode and the negative electrode to be used together with the separator of the present invention are not particularly limited, and the electrode active material may be bound to an electrode current collector according to a conventional method known in the art.

The positive electrode is prepared, for example, by coating a positive electrode current collector with a mixture of a positive electrode active material, a conductive agent and a binder (positive electrode mixture), and drying the positive electrode current collector. If necessary, a filler may be further added to the mixture .

The cathode active material may be a layered compound such as lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals; Lithium manganese oxides such as Li _{1 + x} Mn _{2 -x} O ₄ (where x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ and LiMnO ₂ ; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ and Cu ₂ V ₂ O ₇ ; Formula _{LiNi 1 - x M x O 2} ( where, the M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, x = 0.01 ~ 0.3 Im) Ni site type lithium nickel oxide which is represented by; Formula _{LiMn 2 - x M x O 2} ( where, M = Co, Ni, Fe , Cr, and Zn, or Ta, x = 0.01 ~ 0.1 Im) or Li ₂ Mn ₃ MO ₈ (where, M = Fe, Co, Ni, Cu, or Zn); LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with an alkaline earth metal ion; Disulfide compounds; Fe ₂ (MoO ₄ ) ₃ , and the like. However, the present invention is not limited to these.

The cathode current collector generally has a thickness of 3 to 500 mu m. Such a positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical change in the battery. Examples of the positive electrode current collector include stainless steel, aluminum, nickel, titanium, sintered carbon or a surface of aluminum or stainless steel Treated with carbon, nickel, titanium, silver or the like may be used. The current collector may have fine irregularities on the surface thereof to increase the adhesive force of the cathode active material, and various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric are possible.

The conductive agent is usually added in an amount of 1 to 50% by weight based on the total weight of the positive electrode material mixture containing the positive electrode active material. Such a conductive agent is not particularly limited as long as it has electrical conductivity without causing a chemical change in the battery, and examples thereof include graphite such as natural graphite and artificial graphite; Carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fiber and metal fiber; Metal powders such as carbon fluoride, aluminum, and nickel powder; Conductive whiskers such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used.

The binder is a component which assists in binding of the active material and the conductive agent and bonding to the current collector, and is usually added in an amount of 1 to 50% by weight based on the total weight of the mixture containing the cathode active material. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene -Propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butadiene rubber and the like.

The filler is optionally used as a component for suppressing the expansion of the anode, and is not particularly limited as long as it is a fibrous material without causing a chemical change in the battery. Examples of the filler include olefin polymers such as polyethylene and polypropylene; Fibrous materials such as glass fibers and carbon fibers are used.

The negative electrode is manufactured by applying and drying the negative electrode active material on the negative electrode collector, and if necessary, may include some or all of the positive electrode material mixture components as described above.

The negative electrode collector is generally made to have a thickness of 3 to 500 mu m. Such an anode current collector is not particularly limited as long as it has conductivity without causing chemical change in the battery, and may be formed of a material such as copper, stainless steel, aluminum, nickel, titanium, fired carbon, surface of copper or stainless steel A surface treated with carbon, nickel, titanium, silver or the like, an aluminum-cadmium alloy, or the like can be used. In addition, like the positive electrode collector, fine unevenness can be formed on the surface to enhance the bonding force of the negative electrode active material, and it can be used in various forms such as films, sheets, foils, nets, porous bodies, foams and nonwoven fabrics.

The negative electrode active material may include, for example, carbon such as non-graphitized carbon or graphite carbon; _{Li x Fe 2 O 3 (0≤x≤1} ), Li x WO 2 (0≤x≤1), Sn x Me 1 - x Me 'y O z (Me: Mn, Fe, Pb, Ge; Me' : Metal complex oxides such as Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, Halogen, 0 < x &lt; Lithium metal; Lithium alloy; Silicon-based alloys; Tin alloy; _{SnO, SnO 2, PbO, PbO} 2, Pb 2 O 3, Pb 3 O 4, Sb 2 O 3, Sb 2 O 4, Sb 2 O 5, GeO, GeO 2, Bi 2 O 3, Bi 2 O 4 , and Bi ₂ O ₅ and the like; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials, and the like, but the present invention is not limited thereto.

The non-aqueous electrolyte containing a lithium salt is composed of a nonaqueous electrolyte and lithium. As the non-aqueous electrolyte, a non-aqueous electrolyte, a solid electrolyte, an inorganic solid electrolyte and the like are used.

Examples of the nonaqueous electrolytic solution include N-methylpyrrolidone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyrolactone, 1,2-dimethoxyethane, Methylene chloride, methyl ricinoleate, ricin franc, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, Methyl pyrophosphate, methyl propionate, ethyl propionate, and the like can be obtained by reacting a compound represented by the general formula (1) with a compound selected from the group consisting of trimethoxymethane, dioxolane derivatives, sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, Magnetic organic solvents may be used.

Examples of the organic solid electrolyte include organic polymers such as polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphate ester polymers, agitation lysine, polyester sulfide, polyvinyl alcohol, polyvinylidene fluoride, Polymers containing ionic dissociation groups, and the like can be used.

Examples of the inorganic solid electrolyte include Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N-LiI-LiOH, LiSiO ₄ , LiSiO ₄ -LiI-LiOH, Li ₂ SiS ₃ , Li ₄ SiO ₄ , Nitrides, halides and sulfates of Li such as Li ₄ SiO ₄ -LiI-LiOH and Li ₃ PO ₄ -Li ₂ S-SiS ₂ can be used.

The lithium salt may be dissolved in the non-aqueous electrolyte. For example, LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF _{6, LiSbF 6, LiAlCl 4,} CH 3 SO 3 Li, CF 3 SO 3 Li, (CF 3 SO 2) 2 NLi, chloroborane lithium, lower aliphatic carboxylic acid lithium, lithium tetraphenyl borate and imide have.

For the purpose of improving charge / discharge characteristics, flame retardancy, etc., non-aqueous electrolytes may be used in the form of, for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, N, N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, aluminum trichloride and the like are added It is possible. In some cases, a halogen-containing solvent such as carbon tetrachloride, ethylene trifluoride and the like may be further added to impart nonflammability, and a carbon dioxide gas may be further added to improve high temperature storage characteristics.

As a process for applying the separation membrane according to an embodiment of the present invention, a lamination, stacking and folding process of a separation membrane and an electrode can be performed in addition to a general winding process.

The foregoing description is merely illustrative of the technical idea of the present invention and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas falling within the scope of the same shall be construed as falling within the scope of the present invention.

Example  1: Confirmation of adhesive layer formation

Under a nitrogen atmosphere, polyamide-imide (Torlon ^R 4000T, Solvay Specialty Polymers): polyvinylidene fluoride (KF110, Japan Kureha): N-methyl-pyrrolidone was mixed at a ratio of 5: 1: 94 on a weight basis at 25 DEG C to prepare a polymer solution &Lt; / RTI &gt; The resulting polymer solution was solution-cast on a glass support at a relative humidity of 40% at 80 DEG C, and its surface was magnified 500 times (see Fig. 1).

Example  2: Confirmation of pore formation

Under nitrogen, a polyamide-imide (Torlon ^R, Solvay Advanced Polymer's): polyvinyl alcohol (molecular weight (M _w): 2000, ACROSS): N- methyl-pyrrolidone by weight of 19: 1: 80 at a temperature of 100 캜 to obtain a polymer solution. The resulting polymer solution was solution cast onto a glass support at 80 캜 and 30% relative humidity, and then dried in an oven at 100 캜 for 60 minutes. Subsequently, it was immersed in water to elute polyvinyl alcohol. And its surface was magnified 5000 times (see Fig. 2).

Example  3: Preparation of membrane

Under nitrogen, a polyamide-imide (Torlon ^R 4000T, Solvay Specialty Polymers's): polyvinylidene fluoride (KF110, Kureha Japan), polyvinyl alcohol (molecular weight (M _w): 2000, ACROSS): N- methyl -Pyrrolidone were mixed at a weight ratio of 10: 2: 1: 87 at 100 占 폚 to obtain a polymer solution. The obtained polymer solution was solution-cast on a glass support in a support at a temperature of 80 캜 and a relative humidity of 50% to dry the solvent, and at the same time, polyvinylidene fluoride was phase-separated toward the surface. Thereafter, it was immersed in water to elute polyvinyl alcohol. The surface of the membrane was divided into an air surface not reaching the support and a glass surface touching the support. (See Figs. 3 and 4).

Comparative Example  1: Preparation of membrane

A separation membrane was prepared in the same manner as in Example 3, except that polyvinylidene fluoride as an adhesive layer-forming compound was not used.

Experimental Example : Adhesion test

Two sheets of the EP separating membranes having the adhesive force prepared in Example 3 were superimposed and rolled at a temperature of 100 DEG C, and then the adhesive force between the two EP separating membranes was measured. For the measurement, two membranes having a width of 25 mm and a length of 100 mm were adhered by the above method, and then the ends of the two membranes were fixed to the UTM equipment and pulling force was calculated. A function of the force is shown in FIG. As a result, it was confirmed that the separator had an adhesive force of about 25 gf / 25 mm.

On the contrary, after covering the two membranes prepared in Comparative Example 1 and measuring the adhesive force after roll pressing at a temperature of 100 캜, it was found that there was no adhesive force due to no adhesive force-forming compound used .

Claims (15)

delete delete delete delete delete delete delete delete delete delete delete A method for producing a separator for an electrochemical device,
(S1) dissolving an amorphous polymer compound, an adhesive layer-forming compound and a pore-forming agent in a solvent to obtain a polymer solution;
(S2) applying a polymer solution on the support such that the adhesive layer-forming compound in the polymer solution is phase-separated toward the surface;
(S3) drying the polymer solution applied on the support to obtain a film; And
(S4) The film is peeled off from the support and then dipped in water to elute and remove the pore-forming agent to form pores
Wherein the separator is formed of a metal. 13. The method of claim 12,
Wherein the polymer solution comprises 1 to 20 parts by weight of an amorphous polymer compound, 1 to 20 parts by weight of an adhesive layer-forming compound, 1 to 20 parts by weight of a pore-forming agent, and a residual solvent, based on 100 parts by weight of the solution (Method for manufacturing separator for element).
13. The method of claim 12,
Wherein the pore-forming agent is polyvinylpyrrolidone, polyvinyl alcohol, polyacrylic acid, or a mixture of two or more selected from the foregoing.
13. The method of claim 12,
Wherein the step (S2) is performed at a temperature of 20 to 120 DEG C and a relative humidity of 20 to 80%.

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