KR20140096522A - Manufacturing method of organic-inorganic hybrid porous seperation membrane and organic-inorganic hybrid porous seperation membrane using the same method - Google Patents

Abstract

The present invention relates to a method of manufacturing an organic-inorganic porous separation membrane for a secondary battery and an organic-inorganic porous separation membrane manufactured by the same method. The present invention provides an organic-inorganic hybrid porous separation membrane which includes a porous polyolefin material having pores by performing a microwave thermal process on a polyolefin material including inorganic particles (A). A porous separation membrane according to the present invention improves a process because a stretching process is not included, has a strong bonding force with regard to a material compared to an existing separation membrane, and provides excellent ion conductivity and an excellent battery capacity storage rate.

Description

Technical Field [0001] The present invention relates to a method for producing an organic / inorganic hybrid porous membrane for an organic / inorganic hybrid battery, and a porous organic / inorganic hybrid membrane prepared from the porous organic / inorganic hybrid membrane,

The present invention relates to a method for producing an organic / inorganic porous membrane for a secondary cell and an organic / inorganic porous membrane prepared therefrom.

BACKGROUND ART [0002] With the recent trend toward miniaturization and weight reduction of electronic devices, batteries used as power sources for portable electronic devices are also required to be smaller and lighter. Lithium secondary batteries have been put to practical use as batteries that are small in size and can be charged and discharged with a high capacity.

 The lithium ion battery is used not only as a power source for small electronic devices but also as an electric automobile and an electric bicycle. Accordingly, high-temperature storage characteristics and life characteristics are demanded which are even better than those required for conventional small batteries. In particular, lithium ion batteries for hybrid electric vehicles are required to have improved stability and long-term storage performance.

The lithium _secondary battery is manufactured by using a metal oxide such as LiCoO ₂ as a cathode active material and a carbon material as an anode active material and a polyolefin porous separator between the anode and the cathode and a nonaqueous electrolyte solution containing a lithium salt such as LiPF ₆ do. During charging, lithium ions of the positive electrode active material are released and inserted into the carbon layer of the negative electrode. In discharging, lithium ions of the negative electrode carbon layer are released and inserted into the positive electrode active material. In this case, As shown in FIG.

Here, the porous separator prevents physical contact between the cathode and the anode, and at the same time passes lithium ions through the pores. The separator itself does not participate in the electrochemical reaction during charging and discharging, but has porosity, It may have a great influence on the cycle performance and safety of the battery.

The polyolefin membrane used as a porous separator of the lithium secondary battery currently produced exhibits extreme thermal shrinkage behavior at a temperature of 100 ° C or more due to the characteristics of the manufacturing process including the material properties and elongation, causing a short circuit between the cathode and the anode at a high temperature It may cause a battery accident, and from the viewpoint of mechanical characteristics, the physical rupture characteristic of the separator is weak, so that there is a disadvantage in that internal short circuit of the battery is easily caused by foreign matter in the battery.

Various attempts have been made to improve the thermal stability of the membranes. U.S. Patent No. 6,949,315 (Patent Document 1) discloses a film in which an ultrahigh molecular weight polyethylene is kneaded with an inorganic substance such as titanium oxide in an amount of 5-15% by weight to improve the thermal stability of the separator. However, this method has the effect of improving the thermal stability according to the addition of the inorganic substance, but the problems such as the lowering of the kneading property due to the addition of the inorganic substance and the lowering of the kneading property are liable to occur, Compatibility is insufficient, resulting in deterioration of film properties such as impact strength. This disadvantage is inevitable for separators using inorganic materials.

WO 2006/038532 (Patent Document 2) discloses a multi-layered wet separation membrane containing inorganic particles, and this separation membrane also requires a complicated kneading process due to inorganic kneading. Also, if an inorganic material is added to the surface layer, the inorganic material may be removed from the processes such as stretching / extraction / winding / slitting, resulting in contamination by the inorganic powder and scratching of other surface layers.

As a method for solving such a problem, there is a method of coating a polyolefin film having undergone a stretching process with a polymeric binder containing an inorganic material (ceramic particles), but there is an inefficiency in which winding and winding processes are repeated in the process, Defects or the like may occur, which may adversely affect the safety of the battery.

Therefore, researches on a technique for producing a porous polyolefin substrate without a stretching process and studies for preventing adhesion between the porous polyolefin substrate and the coating layer and desorption of the ceramic particles contained in the coating layer have been urgently required.

U.S. Patent No. 6,949,315 WO 2006/038532

The present invention provides a separator for a secondary battery. Specifically, the separator for a secondary battery has a simple structure because it has no stretching process and has excellent mechanical and thermal characteristics. Thus, even under excessive conditions such as high temperature and overcharge, safety deterioration due to short- The present invention provides an organic / inorganic porous separator having excellent cell characteristics, and more specifically, to provide an organic porous separator having improved electrical stability of a secondary battery by remarkably reducing the adhesive force between the porous film substrate and the coating layer and the desorption of ceramic particles. .

In order to achieve the above object, the present invention provides an organic porous separator comprising a porous substrate having pores formed therein by microwave heat treatment on a polyolefin substrate containing inorganic particles (A).

The present invention also provides a method for preparing a porous polyolefin substrate, comprising: a) microwave heat treatment of a polyolefin substrate comprising inorganic particles (A) to produce a porous poly olefin substrate; and b) And a slurry containing a solvent to form an active layer. The present invention also provides a method for producing an organic / inorganic porous separator.

The present invention also provides a secondary battery comprising the organic or inorganic porous separator, or the organic or inorganic porous separator produced by the production method.

The porous organic / inorganic separator for a secondary battery according to the present invention is effective because it does not have a stretching process of a polyolefin base material, and has excellent mechanical and thermal characteristics. Therefore, even under excessive conditions such as high temperature and overcharging, safety deterioration due to short- Excellent in characteristics. More specifically, it is possible to provide an organic / inorganic porous separator that is easier to provide an organic / inorganic porous separator and that significantly reduces the adhesion between the porous film substrate and the coating layer and the desorption of ceramic particles, thereby improving the electrical stability of the secondary battery.

Also, the porous separator according to the present invention has stronger adhesion to a substrate than conventional separators, and can provide excellent ion conductivity and cell capacity retention.

The present invention provides an organic or inorganic porous separator comprising a porous polyolefin substrate having pores formed by microwave heat treatment on a polyolefin substrate containing inorganic particles (A).

The present invention also provides an organic porous separator comprising an active layer coated with an organic binder polymer mixture formed on the surface of the porous polyolefin substrate.

According to an embodiment of the present invention, the organic binder polymer mixture may be prepared by mixing the active site of the inorganic particles (B) with a C ₆ to C ₃₆ fatty acid or oxidized wax Organic binder polymer mixture.

The inorganic particles (A) may be one or more metal oxides selected from SiO ₂ , Al ₂ O ₃ , TiO ₂ , SnO ₂ , CeO ₂ , ZrO ₂ , BaTiO ₃ and Y ₂ O ₃ , It is not.

The inorganic particles B may be one or more metal oxides selected from SiO ₂ , Al ₂ O ₃ , TiO ₂ , SnO ₂ , CeO ₂ , ZrO ₂ , BaTiO ₃ and Y ₂ O ₃ , It is not.

The active site is not limited as long as it is capable of being modified by the C ₆ to C ₃₆ fatty acid or oxidized wax. Specifically, _{-COO, -NH 2, -CONH 2,} -PO 3 H 2, -SH, -SO 3 H, -SO 2 H, -NO 2 , and _{-O (CH 2 CH 2 O)} n H ( wherein , n can be at least one or two selected from the group consisting of a hydrophobic group and a hydrophilic group an aryl (aryl), a C ₃ ~ C ₃₀ alkyl group and C ₃ ~ C _30, consisting of an integer from 0 to 5).

The C ₆ to C ₃₆ fatty acid or oxidized wax may contain two or more fatty acid groups as terminal groups as a binder.

The present invention may further comprise 1 to 20 parts by weight of inorganic particles (C) per 100 parts by weight of the organic binder polymer mixture.

The inorganic particles (C)₂, Al₂O₃, TiO₂, SnO₂, CeO₂, ZrO₂, BaTiO₃, SrTiO₃, Y₂O₃, MgO, NiO, CaO, ZnO, and SiC.

The secondary battery including the organic / inorganic porous separator according to the present invention is included in the scope of the present invention.

Further, according to the present invention,

a) microwave heat treatment of the polyolefin substrate comprising the inorganic particles (A) to produce a porous poly olefin substrate,

b) forming an active layer by applying a slurry comprising an organic binder polymer mixture and a solvent on at least one surface of the porous polyolefin substrate of step a)

The present invention also provides a method for producing an organic / inorganic porous separator.

At this time, the microwave heat treatment in step a) may be performed by irradiating microwave wavelengths of 0.1 to 10 GHz at a reaction temperature of 50 to 300 ° C.

 It is preferable that the thickness of the active layer of b) is 0.1 to 100 탆 after drying.

The organic or inorganic porous separator produced by the production method of the present invention and the secondary battery comprising the same are also within the scope of the present invention.

Hereinafter, the present invention will be described in detail.

Disclosure of the Invention It is therefore an object of the present invention to provide a porous polyolefin base material and a method of manufacturing the same. Completed.

First, the polyolefin substrate containing the inorganic particles (A) according to one embodiment of the present invention will be described in detail.

The polyolefin substrate containing the inorganic particles (A) according to the present invention may be a substrate in which the inorganic particles (A) are dispersed in the polyolefin resin.

The polyolefin resin used in the present invention is a polyolefin resin used for ordinary extrusion, injection, inflation, blow molding and the like, and includes ethylene, propylene, 1-butene, 4-methyl- Homopolymers and copolymers such as octene, and multi-terminal polymers. Further, these homopolymers and copolymers, polyolefins selected from the group of multistage polymers may be used singly or in combination. Representative examples of the polymer include low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene, ultra high molecular weight polyethylene, isotactic polypropylene, atactic polypropylene, polybutene and ethylene propylene rubber.

The viscosity average molecular weight of the polyolefin resin used in the present invention is preferably from 50,000 to less than 10 million. When the viscosity average molecular weight is 50,000 or more, the melt tension during melt molding becomes large, the moldability tends to be improved, sufficient entanglement is easily imparted, and high strength is liable to occur. If the viscosity average molecular weight is less than 10 million, uniform melt kneading tends to be easily obtained, and sheet formability, particularly, thickness stability tends to be excellent.

Since the polyolefin substrate containing the inorganic particles (A) does not include a separate drawing step, it is preferable to form a film as thin as possible and a preferable range is 10 to 300 탆, but it is not limited thereto.

The inorganic particles A may be one or more metal oxides selected from SiO ₂ , Al ₂ O ₃ , TiO ₂ , SnO ₂ , CeO ₂ , ZrO ₂ , BaTiO ₃ and Y ₂ O ₃ , It is not. When the inorganic particles (A) according to the present invention are irradiated with microwaves, heat is generated at the interface between the polyolefin and the inorganic particles due to the dielectric constant different from that of the polyolefin resin. At this time, the polyolefin at the interface melts to form pores . The size of the inorganic particles (A) is preferably 0.001 to 1 占 퐉 in order to maintain a proper porosity, but is not limited thereto. According to one embodiment of the present invention, TiO ₂ (titania) having a particle diameter of 20 nm is used, but the present invention is not limited thereto.

Also, the organic porous separator according to an embodiment of the present invention may include an active layer coated with an organic binder polymer mixture formed on the surface of the porous polyolefin substrate.

The organic binder polymer mixture may be a conventional one containing ceramic particles and a binder polymer. Specifically, the inorganic binder (B) may be an inorganic binder having an active site modified with a C ₆ to C ₃₆ fatty acid or an oxidized wax A polymer mixture may also be used.

Specifically, according to one embodiment of the present invention, an organic binder polymer mixture comprising a C ₆ to C ₃₆ fatty acid or 1 to 200 parts by weight of an oxidized wax may be provided per 100 parts by weight of the inorganic particles (B).

The inorganic particles B may be one or more metal oxides selected from SiO ₂ , Al ₂ O ₃ , TiO ₂ , SnO ₂ , CeO ₂ , ZrO ₂ , BaTiO ₃ and Y ₂ O ₃ , It is not.

The active layer includes an organic binder polymer mixture in which the active sites of the inorganic particles are modified with a C ₆ to C ₃₆ fatty acid or oxidized wax.

The inorganic particles (B) as the active layer component of the organic / inorganic porous separator according to the present invention serve as a kind of spacer capable of forming fine pores and maintaining the physical form by allowing void spaces between inorganic particles. Generally, even if the temperature is higher than 200 ° C, the physical properties are not changed, so that it plays a role of enhancing the heat resistance.

Other electrochemically time stability, dielectric constant Considering the characteristics of the five or more high dielectric constant wherein the inorganic particles (B) is _{SiO 2, Al 2 O 3,} TiO 2, SnO 2, CeO 2, ZrO 2, BaTiO 3 , and Y ₂ O ₃ , and it is not necessarily limited thereto.

The size of the inorganic particles (B) is not limited, but it is preferably 0.0001 to 10 탆 for the formation of a film having a uniform thickness and proper porosity. Within the above range, maintenance of the physical properties of the organic / inorganic porous separator and control of the size of the desired pore can reduce the possibility of internal short circuit during charging and discharging.

The inorganic particles (B) are characterized by having active sites, and the active sites are not limited as long as they can be modified by the C ₆ to C ₃₆ fatty acids or oxidized waxes. Specifically, _{-COO, -NH 2, -CONH 2,} -PO 3 H 2, -SH, -SO 3 H, -SO 2 H, -NO 2 , and _{-O (CH 2 CH 2 O)} n H ( wherein , n can be at least one or two selected from the group consisting of a hydrophobic group and a hydrophilic group an aryl (aryl), a C ₃ ~ C ₃₀ alkyl group and C ₃ ~ C _30, consisting of an integer from 0 to 5). According to one embodiment of the present invention, it may have an -OH group.

The method of forming the active sites of the inorganic particles can be performed by a conventional method such as an acid plasma treatment.

The C ₆ to C ₃₆ fatty acid or oxidized wax is preferably a binder containing two or more fatty acid groups as terminal groups. When C ₆ to C ₃₆ fatty acids or oxidized waxes have two or more fatty acid groups, they form a crosslinked structure with the active sites on the surface of the inorganic substance to strengthen the bonding force between the inorganic particles. When used as a separator for secondary batteries, It is possible to remarkably eliminate the phenomenon of desorption. Further, it is excellent in adhesion to a base material, so that it is more firmly fixed to a non-polar polyolefin base material, and durability can be further increased.

The organic or inorganic porous separator according to the present invention can be prepared by controlling the content of the inorganic particles (B), which is the constituent of the active layer of the separator base material, and the composition of the fatty acid or oxidized wax of C ₆ to C ₃₆ serving as a binder polymer, And the pore size and porosity can be adjusted together.

Specifically, the organic binder polymer mixture preferably contains 1 to 200 parts by weight of a C ₆ to C ₃₆ fatty acid or oxidized wax used as a binder polymer with respect to 100 parts by weight of the inorganic particles (B). When the amount of the organic binder polymer is less than 1 part by weight, the mechanical properties of the final organic-inorganic hybrid porous membrane may be deteriorated due to the weak adhesive force between the inorganic particles. When the amount of the organic binder polymer exceeds 200 parts by weight, The pore size and porosity may be reduced, resulting in degradation of final cell performance.

Fatty acid monoglyceride, fatty acid monopolyhydroxy alcoholide, and polymerized fatty acid monopolyhydroxy alcoholide may be selected to modify the active site of the inorganic particles with the above-mentioned C ₆ -C ₃₆ fatty acid-containing compound, But is not limited thereto.

The oxidized wax preferably has a molecular weight (Mw) in the range of 200 to 40,000 g / mol, and may be an oxidized wax obtained by oxidizing a polyolefin having a molecular weight (Mw) of 200 to 40,000 g / mol. It is not.

The C ₆ to C ₃₆ fatty acid or oxidized wax according to the present invention is preferably a binder containing two or more fatty acid groups as terminal groups. Containing two or more fatty acid groups forms a crosslinked structure with the active sites on the surface of the inorganic particles and plays a role of strengthening the bonding force between the inorganic particles.

The method for preparing the organic binder polymer mixture can be carried out by adding the C ₆ to C ₃₆ fatty acid or oxidized wax to the inorganic particles containing the active site in a solvent such as acetone or alcohol. This reaction can be carried out in a solvent containing 1 to 20 wt% of the C ₆ to C ₃₆ fatty acid or oxidized wax at a temperature of about 60 ° C to 1 to 24 hours.

The organic or inorganic porous separator according to the present invention may further contain inorganic particles (C) in an amount of 1 to 20 parts by weight based on 100 parts by weight of the organic binder polymer mixture to further improve the lithium ion transferring ability and the piezoelectricity.

The inorganic particles (C) is _{SiO 2, Al 2 O 3,} TiO 2, SnO 2, CeO 2, ZrO 2, BaTiO 3, SrTiO 3, Y 2 O 3, MgO, NiO, CaO, which is selected from ZnO and SiC One or two or more. Other Fig BaTiO to compensate piezoelectricity _{(piexoelectricity) 3, Pb (Zr} , Ti) O 3 (PZT), Pb 1-x La x Zr 1-y Ti y O 3 (PLZT), PB (Mg 3 Nb 2 / _{3) O 3 -PbTiO 3 (PMN} -PT) hafnia (HfO 2) , or mixtures thereof, and the number of days, lithium phosphate (Li ₃ PO _4), lithium titanium phosphate _{(Li x Ti y (PO 4} ) 3, 0 <x <2, 0 <y <3 ), lithium aluminum titanium phosphate _{(Li x Al y Ti z (} PO 4) 3, 0 <x <2, 0 <y <1, 0 <z <3), 14Li 2 O- _{9Al 2 O 3 -38TiO 2 -39P 2} O 5 (LiAlTiP) x O y series glass (0 <x <4, 0 <y <13), lithium lanthanum titanate (Li _x La _y TiO _3, such as 0 < x <2, 0 <y < 3), Li 3 .25Ge0.25P0.75S 4 as lithium germanium thiophosphate Mani Titanium _{(Li x Ge y P z S} w, 0 <x <4, 0 <y < 1, such as, (Li _x N _y , 0 <x <4, 0 <y <2) such as 0 <z <1, 0 <w <5, Li ₃ N and the like, Li ₃ PO ₄ -Li ₂ S- ₂ SiS ₂ based _{glass (Li x Si y S z} , 0 <x <3, 0 <y <2, 0 <z <4), LiI-Li 2 SP 2 S 5 P 2 S 5 , including, such as Thermal glass may further include a _{(Li x P y S z,} 0 <x <3, 0 <y <3, 0 <z <7) or a mixture thereof. And halogen compounds, such as _{AlX 3, MgX 2, SnX 2} ( where, X is a halogen atom) in order to form a solid electrolyte interface even at the electrode surface during the charge and discharge reaction of the secondary battery to improve the cycle characteristics and high rate characteristics of the battery As shown in FIG.

Further, according to the present invention,

a) microwave heat treatment of the polyolefin substrate comprising the inorganic particles (A) to produce a porous poly olefin substrate,

b) forming an active layer by applying a slurry comprising an organic binder polymer mixture and a solvent on at least one surface of the porous polyolefin substrate of step a)

The present invention also provides a method for producing an organic / inorganic porous separator.

Hereinafter, each step of the method for producing an organic / inorganic porous separator will be described in detail.

First, step a) is a step of microwave-heat-treating the polyolefin substrate containing the inorganic particles (A) to prepare a porous poly olefin substrate, which can be produced by a conventional dry method and a wet method.

First, the drying method includes a step of melt-mixing the inorganic particles (A) constituting the polyolefin substrate with the polyolefin. You can use an Extruder or a Banbury mixer. And then extruding the film using an extruder of a polyolefin having evenly dispersed inorganic particles. When the film thus extruded is heat-treated by microwaves, heat is generated due to the permittivity constant between the inorganic particles and the organic material, and the film around the inorganic particles is melted to form voids. The wet method first comprises heating the polyolefin to a temperature of from 100 to 150 DEG C using a solvent such as xylene or chlorobenzene to disperse the polyolefin and dispersing the inorganic particles. The polyolefin in which the inorganic particles are dispersed is cast on a flat substrate and heated to volatilize the solvent. The film produced by the solvent volatilization method is subjected to microwave heat treatment to produce a void.

In this case, the microwave heat treatment can be performed by irradiating microwave wavelengths of 0.1 to 10 GHz at a reaction temperature of 50 to 300 ° C, but is not limited thereto. The reaction time is preferably about 30 seconds to 60 minutes.

INDUSTRIAL APPLICABILITY The porous organic / inorganic hybrid membrane according to the present invention is simpler in process than the organic / inorganic hybrid membrane of the prior art and can provide uniform and desired size and shape porous membrane due to the porous structure by microwave heat treatment instead of the stretching process. In addition, it is possible to solve the problems of the conventional stretching process, such as defective foreign matters due to winding and drawing on the stretching process, and defects due to fine errors in stretching conditions, etc., and to form an effective microporous film. In addition, since the composite membrane of polyolefin and inorganic material is formed and microwave heat treatment is performed, the mechanical strength of the separator can be improved because the structure becomes harder than the porous membrane of the polyolefin itself .

Next, in step b), a slurry containing an organic binder polymer mixture and a solvent is applied to at least one surface of the porous polyolefin substrate of step a) to form an active layer.

In this case, the organic binder polymer mixture may be in the form of an inorganic particle (B) dispersed in a binder polymer, and more preferably, an organic / inorganic hybrid material modified with a C ₆ to C ₃₆ fatty acid or an oxidized wax Binder polymer mixture.

Non-limiting examples of the binder polymer include polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-trichlorethylene, polymethyl methacrylate, polyacrylonitrile, polyvinyl pyrrolidone, polyvinyl acetate , Ethylene vinyl acetate copolymer, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylflurane, cyanoethyl sucrose, pullulan, carboxymethylcellulose, acrylonitrile styrene butadiene copolymer , Polyimide, or a mixture thereof.

The inorganic particles (B) may be one or more metal oxides selected from SiO ₂ , Al ₂ O ₃ , TiO ₂ , SnO ₂ , CeO ₂ , ZrO ₂ , BaTiO ₃ and Y ₂ O ₃ , It is not

The organic binder polymer mixture prepared by modifying the active site of the inorganic particles (B) with a C ₆ to C ₃₆ fatty acid or an oxidized wax is as described above.

A solvent is contained in the organic binder polymer mixture to prepare a slurry. The slurry can be prepared by adding a solvent to the organic binder polymer mixture and using a mixer, a dispersing machine, etc. at a temperature ranging from room temperature to 60 ° C. The slurry according to the present invention can be produced in the form of a slurry in which inorganic particles are uniformly dispersed without requiring a separate dispersant and a dispersing step. Since the organic binder is chemically bonded to the inorganic particles, It seems to be possible to maintain the form.

The solvent used in the slurry dissolves C ₆ to C ₃₆ fatty acids or oxidized waxes. The active sites of porous polyolefin-based and inorganic particles must have non-solvent properties. Examples of such solvents include acetone, tetrahydrofuran, Acetonitrile, dimethylformamide, dimethyl sulfoxide, diethylacetamide, N-methylpyrrolidone, and water. These solvents may be used in combination of two or more thereof.

Also, the solvent may include 10 to 1000 parts by weight based on 100 parts by weight of the organic binder polymer mixture, and a suitable slurry viscosity and an appropriate coating layer may be formed within the above range.

Conventional organic and inorganic porous separators have the advantage of excellent stability when applied to lithium ion batteries. However, when a lithium ion battery is stored at a high temperature for a long time, the moisture that was present during the production of the lithium ion battery increases the resistance The performance is deteriorated due to the reasons such as the above. In particular, since the inorganic material forming the separation membrane is hydrophilic, the water is strongly adsorbed chemically, resulting in degradation of long-term storage performance. However, since the inorganic porous particles according to the present invention are modified with C ₆ to C ₃₆ fatty acids or oxidized waxes to suppress side reactions between water and electrolytes and are strongly adhered to the polyolefin substrate, the electrical and thermal stability and Not only has an effect of improving electrolyte wettability but also excellent durability and high-temperature storage performance.

The slurry may further comprise an additive. As the additive, an additive having a functional group reactive with the OH group may be used.

Further, the additive may have a functional group selected from at least one of phosphonate or phosphate (P = O), posiphonic acid (POH), silane (SiOR) and carboxylic acid (COOH).

Preferably, the additive is selected from the group consisting of dimethyl dimethoxy silane, dimethyl diethoxy silane, methyl trimethoxy silane, vinyl trimethoxy silane, phenyl Silanes such as phenyl trimethoxy silane and tetraethoxy silane, phosphonic acids such as phenyl phosphonic acid and methyl phosphonic acid, Phosphonates such as triphenyl phosphate and diemthyl methyl phosphonate, carboxylic acid esters such as octanoic acid, gallic acid and aminobenzoic acid, carboxylic acid).

When the additive is added in an amount of less than 0.1 wt%, the improvement of the long-term storage performance hardly occurs, and when the additive is added in an amount exceeding 3 wt%, there is no difference in performance from 0.1 wt% to 3 wt%. Therefore, the additive is preferably added in the range of 0.1 to 3 wt%.

At this time, when the organic / inorganic porous separator of the present invention is used as a separation membrane of an electrochemical device, preferably a lithium secondary battery, lithium ions can be delivered not only through the separation membrane substrate but also through the porous active layer, In the case where an internal short circuit occurs, the above-described safety improvement effect can be exhibited.

The present invention also provides a secondary battery comprising an anode, a cathode, an organic / inorganic hybrid porous separator of the present invention interposed between the anode and the cathode, and an electrolyte. Lithium secondary batteries, lithium-ion secondary batteries, lithium polymer secondary batteries, or lithium-ion polymer secondary batteries, and the like.

The electrochemical device can be manufactured according to a conventional method known in the art. For example, the electrochemical device is manufactured by interposing the electrode and the separator interposed therebetween, and then injecting an electrolyte into the assembly.

There is no particular limitation on the electrode to be used together with the organic / inorganic porous separator. However, the cathode active material may be a conventional cathode active material that can be used for a cathode of a conventional electrochemical device. Examples thereof include lithium manganese oxide, A lithium intercalation material such as a composite oxide formed by a lithiated cobalt oxide, a lithium nickel oxide, or a combination thereof, and the like. The negative electrode active material may be a conventional negative electrode active material that can be used for a negative electrode of a conventional electrochemical device. Examples of the negative electrode active material include lithium metal, lithium alloy and carbon, petroleum coke, Activated carbon, graphite or other lithium-absorbing materials such as carbon and the like. The positive electrode current collector may be a positive current collector, that is, a foil and a negative electrode current collector made of aluminum, nickel, or a combination thereof, that is, copper, gold, nickel or a copper alloy or a combination thereof And both electrodes are formed in such a manner that they are bonded to a foil produced by the above method.

An electrolytic solution used in the present invention is A ⁺ B ^- A salt of the structure, such as, A ⁺ is Li ^+, Na ^+, and comprising an alkali metal cation or an ion composed of a combination thereof, such as K ^+, B ^- is PF ₆ ^{- _{, BF 4 -, Cl -,}} Br -, I -, ClO 4 -, AsF 6 -, CH 3 CO 2 -, CF 3 SO 3 -, N (CF 3 SO 2) 2 -, C (CF 2 SO 2 ) ₃ ^- , or an ionic ion-containing salt such as propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate DMC), dipropyl carbonate (DPC), dimethylsulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N- N-methyl-2-pyrrolidone (NMP), ethylmethyl car- bonate it is preferably dissolved and dissociated in an organic solvent composed of gamma-butanoate (EMC), gamma-butyrolactone (GBL), or a mixture thereof.

The electrolyte injection may be performed at an appropriate stage of the battery manufacturing process, depending on the manufacturing process and required properties of the final product. That is, it can be applied before assembling the cell or at the final stage of assembling the cell.

The process of applying the organic or inorganic porous separator according to the present invention to a battery can be a lamination and folding process of a separation membrane and an electrode in addition to a general winding process.

When the organic or inorganic porous separator of the present invention is applied to the lamination process, it can be easily assembled due to excellent adhesive properties of fatty acids or oxidized waxes of C ₆ to C _{36 in} the active layer. At this time, the adhesive force characteristics can be controlled by the content of the main inorganic particles and the fatty acid or oxidized wax of C ₆ -C ₃₆ or the physical properties of the polymer.

Hereinafter, preferred embodiments will be described in order to facilitate understanding of the present invention. However, the following examples are illustrative of the present invention, and the scope of the present invention is not limited to the following examples.

[Example 1]

1. Preparation of Membrane

30% by weight of high density polyethylene "SH800" (trade name, manufactured by Asahi Kasei Chemicals Co., Ltd.) having an average molecular weight (Mv) of 270,000 and ultra high molecular weight polyethylene "UH850" (trade name, manufactured by Asahi Kasei Chemicals Co., Ltd.) 10% by weight of titania nanoparticles (TiO _2, PC-101, anatase type crystal of Japan Titan Industry Co., average particle diameter: 20 nm, specific surface area: 340 m 2 / g), and liquid paraffin wax 19% by weight of "P-350P" (trade name, manufactured by Matsumura Chemical Industries, Ltd.) as an antioxidant, pentaerythrityl tetrakis- [3- (3,5- Hydroxyphenyl) propionate] was added to a Banbury mixer and mixed. The resulting mixture was extruded with an extruder to obtain a polyolefin base material containing sheet-like inorganic particles (A) having a thickness of 100 mu m.

The polyolefin substrate was irradiated with a microwave wavelength of 8 GHz at a temperature of 80 캜 for 10 minutes in a nitrogen atmosphere to prepare a microporous porous polyolefin substrate .

2. Ion conductivity measurement

The porous polyolefin substrate prepared as described above was used as a separator, and each electrolyte was immersed in the electrolyte solution, and then taken out again to measure ionic conductivity.

At this time, a lithium hexafluorophosphate salt was dissolved in a mixed solvent of ethylene carbonate / dimethyl carbonate (volume ratio 1: 1) at a concentration of 1M, and the electrolyte was used.

[Example 2]

1. Preparation of Membrane

SiO ₂ powder was subjected to acid plasma treatment to form an -OH active site, and a C ₁₆ fatty acid monoglyceride prepared in a concentration of 20% (w / w) in acetone was added to 100 parts by weight of the SiO ₂ powder in which the active site was formed Were added and the mixture was reformed at room temperature for 24 hours while stirring to prepare an organic binder polymer mixture.

100 parts by weight of the organic binder polymer mixture was mixed with 300 parts by weight of a mixed solvent of acetone and tetrahydrofuran in a volume ratio of 1: 1 to prepare a slurry. The slurry thus prepared was coated on the polyolefin microporous membrane substrate of Example 1 having a thickness of 100 占 퐉 by dip coating method and dried in an oven at 70 占 폚 for 30 seconds to prepare a composite membrane. The thickness of the coated active layer after drying was adjusted to be 50 탆.

2. Ion conductivity measurement

The separation membranes prepared by the method of Example 2 were each immersed in an electrolytic solution and taken out again to measure the ion conductivity.

At this time, a lithium hexafluorophosphate salt was dissolved in a mixed solvent of ethylene carbonate / dimethyl carbonate (volume ratio 1: 1) at a concentration of 1M, and the electrolyte was used.

[Example 3]

The ionic conductivity was measured in the same manner as in Example 2, except that the oxidation wax having a molecular weight (Mw) of 1200 (g / mole) was used instead of the fatty acid monoglyceride of C ₁₆ in the separation membrane production step.

[Comparative Example 1]

1. Preparation of Membrane

100 parts by weight of polyvinylsulfonate having a molecular weight of 1,000 (g / mole) per 100 parts by weight of SiO ₂ powder, 300 parts by weight of a solvent mixed at a volume ratio of 1: 1 of acetone and tetrahydrofuran was added and stirred to prepare a slurry . The slurry thus prepared was coated on an unoriented polyethylene substrate having a thickness of 500 탆 by a dip coating method and dried in an oven at 70 캜 for 30 seconds to prepare a composite membrane. The thickness of the coated active layer after drying was adjusted to be 50 탆.

The thus prepared composite membrane was subjected to longitudinal stretching at a longitudinal stretching temperature of 100 占 폚 and a longitudinal stretching magnification of 5 times, followed by transverse stretching at a transverse stretching temperature of 110 占 폚 and a transverse stretching magnification of 5, Organic porous separator.

2. Ion conductivity measurement

The ionic conductivity of the separator prepared in Comparative Example 1 was measured by the method of Example 1.

The ion conductivity values of Examples 1 to 3 and Comparative Example 1 are shown in Table 1 below.

[Table 1]

Using the separators of Examples 1 to 3 and Comparative Example 1, a lithium secondary battery was fabricated as follows.

Manufacture of anode

88 wt% of LiCoO ₂ as a positive electrode active material, 6.5 wt% of carbon black as a conductive agent, and 5.5 wt% of PVdF as a binder were added to N-methyl-2-pyrrolidone (NMP) as a solvent to prepare a positive electrode mixture slurry. The positive electrode mixture slurry was applied to an aluminum thin film having a thickness of 20 탆 and dried to prepare a positive electrode, followed by roll pressing.

Cathode manufacturing

A negative electrode mixture slurry was prepared by adding 92 wt% of carbon powder, 6 wt% of PVdF as a binder and 2 wt% of carbon black as a negative active material to N-methyl-2-pyrrolidone (NMP) as a solvent. The positive electrode mixture slurry was applied to a copper thin film having a thickness of 20 탆 and dried to prepare a negative electrode, followed by roll pressing.

Manufacture of lithium secondary battery

Each of the positive electrode, the negative electrode, and the separators of Examples 1 and 2 and Comparative Example 1 was assembled using a stacking method, and 1 M of lithium hexafluorophosphate dissolved in ethylene carbonate: ethyl methyl carbonate = 1 : 2 (volume ratio) was injected to prepare a lithium secondary battery.

Each of the secondary batteries using the separators of Examples 1 and 2 and Comparative Example 1 thus manufactured was subjected to charge and discharge tests at a current density of 0.5 C in the range of 2.8 to 4.2 V. [ Specifically, the retention rate (%) obtained by measuring the capacity rate relative to the initial capacity obtained by 300 cycles of charging / discharging was measured, and the results are shown in Table 2 below.

[Table 2]

 It can be seen that the organic / inorganic porous separator according to the present invention has excellent ionic conductivity and charge / discharge retention ratio. It can be seen that the polyolefin substrate prepared by the stretching process has better ion conductivity and retention than the polymer- .

Claims (14)

An inorganic or organic porous separator comprising a porous polyolefin substrate having pores formed by microwave heat treatment on a polyolefin substrate containing inorganic particles (A). The method according to claim 1,
And an active layer coated with an organic binder polymer mixture formed on the surface of the porous polyolefin substrate. 3. The method of claim 2,
Wherein the organic binder polymer mixture is a mixture of an organic binder polymer modified with a C ₆ to C ₃₆ fatty acid or an oxidized wax at the active site of the inorganic particles (B). The method according to claim 1,
The inorganic particles (A) is _{SiO 2, Al 2 O 3,} TiO 2, SnO 2, CeO 2, ZrO 2, BaTiO 3 And Y &lt; ₂ &gt; O &lt; ₃ &gt;. The method of claim 3,
The inorganic particles (B) is _{SiO 2, Al 2 O 3,} TiO 2, SnO 2, CeO 2, ZrO 2, BaTiO 3 , and Y one or more than one metal oxide, inorganic porous separator is selected from ₂ O _3. The method of claim 3,
The active site neunneun _{-COO, -NH 2, -CONH 2,} -PO 3 H 2, -SH, -SO 3 H, -SO 2 H, -NO 2 And a hydrophobic group composed of a hydrophilic group composed of -O (CH ₂ CH ₂ O) _n H (where n is an integer of 0 to 5), a C ₃ to C ₃₀ alkyl group, and a C ₃ to C ₃₀ aryl group Porous separator having one or more porous separators. The method of claim 3,
Further comprising 1 to 20 parts by weight of inorganic particles (C) per 100 parts by weight of the organic binder polymer mixture. 8. The method of claim 7,
The inorganic particles (C) is _{SiO 2, Al 2 O 3,} TiO 2, SnO 2, CeO 2, ZrO 2, BaTiO 3, SrTiO 3, Y 2 O 3, MgO, NiO, CaO, which is selected from ZnO and SiC One or two or more organic porous membranes. A secondary battery comprising any one of the organic or inorganic porous membranes selected from claims 1 to 8. a) microwave heat treatment of the polyolefin substrate comprising the inorganic particles (A) to produce a porous poly olefin substrate,
b) forming an active layer by applying a slurry comprising an organic binder polymer mixture and a solvent on at least one surface of the porous polyolefin substrate of step a)
Wherein the porous separator is a porous membrane. 11. The method of claim 10,
Wherein the microwave heat treatment in the step a) is performed at a reaction temperature of 50 to 300 ° C in a microwave wavelength of 0.1 to 10 GHz. 11. The method of claim 10,
Wherein the active layer of b) has a thickness of 0.1 to 100 m after drying. An organic or inorganic porous separator produced by the method of any one of claims 10 to 12. 13. A secondary battery comprising the porous organic / inorganic composite membrane of claim 13.