TWI636605B - Slurry with improved dispersibility and its use - Google Patents

Abstract

The present invention relates to an invention for controlling the viscosity of a slurry for manufacturing an electrochemical device by adjusting the particle diameter of an inorganic substance which is a component of the slurry so that the rate of sinking of the inorganic particles can be Significantly slower and dispersibility can be greatly improved, and thus the content of the inorganic particles can be relatively increased and the inorganic particles can be uniformly distributed in the coating on the substrate, thereby preventing a decrease in battery performance.

Description

Dispersed improved slurry and use thereof

The present invention relates to a slurry having improved dispersibility and its use, and more particularly to controlling the particle size of an inorganic substance in a slurry comprising inorganic particles, an organic binder polymer and a solvent as a component to a predetermined A slurry having a range of improved dispersion of inorganic particles, and a separator or electrode mixture for electrochemical devices produced using the slurry.

With the growing demand for batteries for power supplies, there is an increasing interest in rechargeable electrochemical devices, and in particular, the demand for and interest in lithium secondary batteries is further increasing.

The lithium secondary battery includes an electrode assembly composed of a cathode, a separator, and an anode. The separator can be produced by coating a porous polymer substrate with a slurry comprising inorganic particles and an organic binder polymer, followed by drying, and the cathode and the anode are bonded by inorganic particles including the use as an active material and organic bonding. A slurry of the electrode mixture of the polymer of the polymer is applied to the electrode current collector for manufacture. The slurry comprises inorganic particles for the purpose of intercalcating/deintercalating lithium ions or improving ion conductivity of the electrolyte solution. Sex, but these inorganic particles tend to sink over time. Therefore, when the inorganic particles are unevenly dispersed in the slurry or sink due to low dispersion stability, condensation occurs after the slurry is applied to the porous polymer substrate or the electrode current collector (hereinafter referred to as "substrate") or Deposition. Therefore, the adhesion strength between the inorganic particles in the slurry and the substrate is lowered, and when the charging and discharging of the battery are performed, separation between the inorganic particles or between the inorganic particles and the substrate occurs. The inorganic particles do not fulfill their functions.

In order to solve this problem, research has been conducted to improve the dispersibility of inorganic particles, for example, a technique in which a surfactant is used as a dispersing agent when the active material and carbon black are dispersed in a solvent. However, since the surfactant on the surface of the particles has low adsorptivity, a large amount of surfactant is required to achieve good dispersion stability. As a result, the amount of inorganic particles which may be included in the slurry is relatively reduced, and thus the inorganic particles are not easily able to achieve their inherent functions. Further, if the adsorbent of the surfactant is insufficient on the particles, the inorganic particles are easily cohesive. Further, in general, the surfactant has a very low dispersion effect in an organic solvent as compared with dispersion in a water-soluble solution.

This case is designed to solve the problem that in the slurry including inorganic particles as a component, the inorganic particles are prematurely sunk due to insufficient dispersibility of the inorganic particles, and the inherent function cannot be realized. That is, the present invention relates to providing a slurry having improved dispersibility of inorganic particles, and a separator and electrode mixture for use in an electrochemical device having excellent battery performance, which is produced using the slurry.

According to an exemplary embodiment of the present invention, there is provided a slurry comprising inorganic particles, an organic binder polymer and a solvent, wherein the inorganic particles have a diameter in the range of 0.01 μm to 15 μm, and the slurry has a lower limit according to the inorganic particles. The diameter is obtained from the value shown below and the upper limit is 10,000 cP:

Where η represents the viscosity of the slurry, and d represents the average diameter of the inorganic particles.

The slurry is characterized by comprising 10 to 50 parts by weight of inorganic particles and 1 to 10 parts by weight of an organic binder polymer based on 100 parts by weight of the solvent.

The inorganic particles may be selected from the group consisting of inorganic particles having a dielectric constant greater than or equal to 5, inorganic particles having lithium ion transporting ability, and mixtures thereof.

The inorganic particles having a dielectric constant greater than or equal to 5 may be selected from any of the group consisting of BaTiO ₃ , Pb(Zr _x , Ti _1-x )O ₃ (PZT, 0<x< 1), Pb _1-x La _x Zr _1-y Ti _y O ₃ (PLZT, 0<x<1, 0<y<1), (1-x)Pb(Mg _1/3 Nb _2/3 )O _3-x PbTiO ₃ (PMN-PT, 0<x<1), yttrium oxide (HfO ₂ ), SrTiO ₃ , SnO ₂ , CeO ₂ , MgO, NiO, CaO, ZnO, ZrO ₂ , SiO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , SiC and TiO ₂ , or a mixture thereof.

The inorganic particles having lithium ion transport capability may be selected from any of the group consisting of 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), (LiAlTiP) _x O _y is a substrate glass (0<x<4, 0<y<13), lithium titanate strontium (Li _x La _y TiO ₃ , 0<x<2, 0<y<3), lithium sulphate锗(Li _x Ge _y P _z S _w , 0<x<4, 0<y<1, 0<z<1, 0<w<5), lithium nitride (Li _x N _y , 0<x<4 , 0<y<2), glass with SiS ₂ (Li _x Si _y S _z , 0<x<3, 0<y<2, 0<z<4) as the base material and P ₂ S ₅ (Li _x P _y S _z , 0 < x < 3, 0 < y < 3, 0 < z < 7) is a substrate glass, or a mixture thereof.

The inorganic particles may be selected from any of the group consisting of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium copper oxide, vanadium oxide and disulfide, or the like. mixture.

The inorganic particles may be selected from any of the following groups: non-graphitizable carbon, graphite-based carbon, metal composite oxide, lithium metal, lithium alloy, ruthenium-based A quality alloy, a tin-based alloy, a conductive polymer, and a compound based on Li-Co-Ni, or a mixture thereof.

The organic binder polymer may be selected from any one of the group consisting of polyvinylidene fluoride (PVdF) as a base polymer compound, polyvinylidene fluoride-co-trichloroethylene, Polyvinylidene fluoride-co-hexafluoropropylene, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, polyethylene-co-vinyl acetate, polyethylene oxide, Cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl polytriglucose, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, polytriglucose, carboxymethyl cellulose , acrylonitrile-styrene-butadiene copolymer and polyimine, or a mixture thereof.

The solvent may be selected from the group consisting of acetone, tetrahydrofuran, dichloromethane, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane and water, or a mixture of them.

According to an exemplary embodiment of the present invention, a composite separator for an electrochemical device fabricated using the slurry described above is provided.

According to an exemplary embodiment of the present invention, a cathode mix for an electrochemical device fabricated using the slurry described above is provided.

According to an exemplary embodiment of the present invention, an anode mix for an electrochemical device fabricated using the slurry described above is provided.

According to an exemplary embodiment of the present invention, there is provided an electrochemical device comprising a cathode, an anode, and a separator interposed between the cathode and the anode, wherein at least one of the cathode, the anode, and the separator is as described above Slurry production.

The viscosity of the slurry is adjusted to a predetermined range by using inorganic particles having a predetermined diameter range according to the present invention in the slurry, and therefore, the dispersibility of the inorganic particles is remarkably improved and the sinking rate thereof is also remarkably lowered. Further, in the separator and the electrode mixture produced by using the slurry, a relatively large amount of inorganic particles can be used, and between inorganic particles or inorganic particles can be suppressed. The separation phenomenon between the substrates, thereby effectively preventing the battery performance from deteriorating.

Figures 1a and 1b show the slurry obtained immediately after the preparation of Concrete Example 1-1 (Figure 1a) and the slurry obtained after one day (Figure 1b).

Figures 2a and 2b show the slurry obtained immediately after the preparation of Comparative Example 1-1 (Figure 2a) and the slurry obtained after one day (Figure 2b).

It should be understood that the terms used in the specification and appendices of the patent application should not be construed as being limited to the general and dictionary meanings, but based on the principle that allows the inventor to properly define the terms for the best explanation, according to the technology corresponding to the present invention. The meaning and concept of the form are explained.

Furthermore, the descriptions set forth herein are for illustrative purposes only and are not intended to limit the scope of the present invention, and it is understood that other equivalents and modifications may be made without departing from the spirit and scope of the invention.

A slurry according to an exemplary embodiment of the present invention may be used to manufacture a separator or an electrode mixture for an electrochemical device, and the slurry including the inorganic particles, the organic binder polymer, and the solvent is characterized by the diameter of the inorganic particles In the range of 0.01 μm to 15 μm, and the slurry has a lower limit based on the diameter of the inorganic particles from the equation shown below and the upper limit is 10,000 cP:

Where η represents the viscosity of the slurry, and d represents the average diameter of the inorganic particles.

Equation 1 is based on Equation 3, which is represented by a simple form of the Stoke-Einstein equation of Equation 2, which is a function of particle size and fluid viscosity, as shown by the law of amplification:

Where v _s represents the sinking rate of spherical inorganic particles (unit: μm / s), ρ _p represents the particle density (unit: kg / m ³ ), ρ _f represents the fluid density (unit: kg / m ³ ), η represents the fluid Viscosity (unit: Ns/m ² ), g represents the gravitational acceleration (unit: μm/s ² ), and r represents the radius (unit: μm) of the spherical inorganic particles.

Where η represents fluid viscosity (unit: cP), d represents diameter of spherical inorganic particles (unit: μm), and η ₀ and The initial fluid viscosity (unit: cP) and the diameter of the initial spherical inorganic particles (unit: μm) are respectively indicated.

The slurry according to the specific example of the present case is characterized by the use of a diameter Inorganic particles in the range of 0.01 μm to 15 μm. For example, as used in the specific examples 1-1 and 2-1 of the present invention, inorganic particles having a diameter in the range of 200 to 500 nm may be used, and inorganic particles having a diameter of more than 10 μm and less than or equal to 15 μm may be used. In this example, the viscosity of the slurry is from the upper limit of 10,000 cP to the lower limit set by Equation 1 according to the diameter of the inorganic particles.

Further, the slurry may include 10 to 50 parts by weight of inorganic particles and 1 to 10 parts by weight of the organic binder polymer based on 100 parts by weight of the solvent.

The use of less than 10 parts by weight of the inorganic particles is not sufficient to change the viscosity by the inorganic particles, and the use of more than 50 parts by weight of the inorganic particles makes it difficult to manufacture the electrode mixture or the separator.

The organic binder polymer particles included in the slurry contribute to the viscosity change of the slurry, and it is not sufficient to use less than 1 part by weight of the organic binder polymer based on 100 parts by weight of the slurry solvent. The organic binder polymer particles change the viscosity, and the use of more than 10 parts by weight of the organic binder polymer reduces battery performance.

According to an exemplary embodiment of the present invention, a slurry according to an exemplary embodiment of the present invention may be applied to a composite separator including a porous polymer substrate and a porous coating layer formed on at least one surface of the porous polymer substrate, and includes inorganic particles. And a mixture of organic binder polymers.

The composite separator is manufactured by a method comprising the steps of: preparing a planar polymer substrate having pores, and coating a porous polymer substrate by slurry comprising inorganic particles, an organic binder polymer, and a solvent; of A porous coating layer is formed on at least one surface.

The term "porous coating" as used herein includes a mixture of inorganic particles and a binder polymer, and means that the inorganic particles are bonded to each other by the binder polymer while the inorganic particles are deposited in contact with each other. The structure, wherein the interstitial volume between the inorganic particles, and the interstitial volume between such inorganic particles, is defined as a blank space and forms pores.

The inorganic particles which can be used in the slurry for producing the composite separator (also referred to as "slurry of the separator") can be selected from the group consisting of inorganic particles having a dielectric constant greater than or equal to 5, Inorganic particles of lithium ion transport capacity, and mixtures thereof.

As a specific example, inorganic particles having a dielectric constant greater than or equal to 5 may be selected from any of the following groups: BaTiO ₃ , Pb(Zr _x , Ti _1-x )O ₃ (PZT, 0) <x<1), Pb _1-x La _x Zr _1-y Ti _y O ₃ (PLZT, 0<x<1, 0<y<1), (1-x)Pb (Mg _1/3 Nb _{2/ 3} ) O _3-x PbTiO ₃ (PMN-PT, 0<x<1), yttrium oxide (HfO ₂ ), SrTiO ₃ , SnO ₂ , CeO ₂ , MgO, NiO, CaO, ZnO, ZrO ₂ , SiO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , SiC and TiO ₂ , or a mixture thereof.

Furthermore, as a specific example, the inorganic particles having lithium ion transport capability may be selected from any of the following groups: lithium phosphate (Li ₃ PO ₄ ), lithium lithium 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 ), glass with (LiAlTiP) _x O _y as the substrate (0<x<4, 0<y<13), lithium tantalate strontium (Li _x La _y TiO ₃ , 0<x<2, 0<y< 3), lithium sulphate bismuth (Li _x Ge _y P _z S _w , 0<x<4, 0<y<1, 0<z<1, 0<w<5), lithium nitride (Li _x N _y , 0<x<4, 0<y<2), glass with SiS ₂ (Li _x Si _y S _z , 0<x<3, 0<y<2, 0<z<4) as the base material and P ₂ S ₅ (Li _x P _y S _z , 0 < x < 3, 0 < y < 3, 0 < z < 7) is a substrate glass, or a mixture thereof.

The inorganic particles preferably have a diameter in the range of 0.01 μm to 15 μm for the purpose of forming a uniform thickness and ensuring proper porosity and adjusting the viscosity of the slurry. When the diameter is less than 0.01 μm, the surface area is increased, which hinders the adjustment of the physical properties of the organic/inorganic composite porous separator, and when the diameter exceeds 15 μm, the thickness of the organic/inorganic composite porous separator manufactured by the same solid content increases. Moreover, the mechanical properties are deteriorated, and an excessively large aperture improves the possibility of an internal short circuit during charging and discharging of the battery.

When such inorganic particles are used, even if the inorganic particles are included in the slurry of the separator at a relatively high concentration, the inorganic particles may be present in the slurry of the separator in a physical and chemically stable manner.

The organic binder polymer which can be used in the slurry of the separator may be any one selected from the group consisting of polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-copolymer-three Vinyl chloride, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, polyethylene-co-vinyl acetate, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, Cellulose acetate propionate, cyanoethyl polytriglucose, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, polytriglucose, carboxymethyl cellulose, acrylonitrile-styrene-butadiene Copolymers and polyimines, or mixtures thereof.

If the porous polymer substrate usable for the composite separator is one of the substrates used in the art, it is not limited to a special type, for example, from, for example, polyethylene A porous polymer film formed of a polyolefin of olefin or polypropylene and performing a shutdown function at a temperature of 80 to 130 °C. It is apparent that the porous polymer film can be produced using other polymers (e.g., polyester, etc.) different from polyolefins. Further, as the porous polymer substrate, a porous polymer nonwoven substrate made of polyolefin or polyethylene terephthalate which is commonly used in the art can also be used.

The solvents which can be used to make the composite separator can each independently be selected from any one of the following: acetone, tetrahydrofuran, dichloromethane, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP). ), cyclohexane and water, or a mixture thereof.

In other exemplary embodiments of the present invention, the slurry may correspond to a slurry for electrode mix (hereinafter referred to as "slurry of electrode mixture"). The slurry of the electrode mixture includes inorganic particles such as an anode active material or a cathode active material, and an organic binder polymer, and the slurry of the prepared electrode mixture is applied to an anode current collector or a cathode current collector.

The inorganic particles (i.e., cathode active materials) used in the slurry of the cathode mixture according to the exemplary embodiment of the present invention may include, but are not limited to, layered compounds such as lithium cobalt oxide (LiCoO ₂ ) and lithium nickel oxide ( LiNiO ₂ ) or a compound substituted with at least one transition metal; lithium manganese oxide chemically represented by the following formula: Li _1+x Mn _2-x O ₄ (here, x=0 to 0.33) or LiMnO ₃ , LiMn ₂ O ₃ and LiMnO ₂ ; lithium copper oxide (Li ₂ CuO ₂ ); vanadium oxide such as LiV ₃ O ₈ , LiFe ₃ O ₄ , v ₂ O ₅ and Cu ₂ V ₂ O ₇ ; Ni-type represented by the following chemical formula Lithium nickel oxide: LiNi _1-x M _x O ₂ (here, M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, x = 0.01 to 0.3); lithium manganese composite represented by the following formula Oxide: LiMn _2-x M _x O ₂ (here, M = Co, Ni, Fe, Cr, Zn or Ta < x = 0.01 - 0.1) or Li ₂ Mn ₃ MO ₈ (here, M = Fe, Co, Ni, Cu or Zn); LiMn ₂ O ₄ , wherein a part of Li in the chemical formula is substituted by an alkaline earth metal ion; a disulfide; Fe ₂ (MoO ₄ ) ₃ or the like.

Further, the inorganic particles (i.e., the anode active material) used in the slurry of the anode mixture may use, for example, carbon such as non-graphitizable carbon and graphite-based carbon; metal composite oxide such as Li _x Fe ₂ O ₃ (0 x 1), Li _x WO ₂ (0 x 1), and Sn _x Me _1-x Me' _y O _z (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, elements of Groups 1, 2 and 3 of the periodic table; halogen ;0<x 1;1 y 3;1 z 8); lithium metal; lithium alloy; alloy based on ruthenium; alloy based on tin; metal oxides such as 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 ; conductive polymers such as polyacetylene; Li-Co-Ni As the material of the substrate, etc., the case is not limited to this. The graphite may have an amorphous shape, a planar shape, a small plate shape or a granular shape or the like. Further, a ruthenium-graphite or tin-graphite composite active material produced by mixing graphite and bismuth or tin and pulverizing and sintering the mixture may be used.

In the slurry of the electrode mixture according to the exemplary embodiment of the present invention, the general organic binder polymer of the present technology may be used as long as it satisfies the provision of inorganic particles having a predetermined diameter range and a predetermined viscosity range. The purpose of the slurry may be, but the preferred organic binder polymer may be any one selected from the group consisting of: polyvinylidene fluoride-co-polymerization- Hexafluoropropylene, polyvinylidene fluoride-co-trichloroethylene, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, polyethylene-co-vinyl acetate, polyepoxy Ethane, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl polytriglucose, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, polytriglucose, carboxymethyl Cellulose, acrylonitrile-styrene-butadiene copolymer and polyimine, or a mixture thereof.

In addition to the inorganic particles, the slurry of the electrode mixture according to the present invention may additionally or alternatively include other components such as a conductive material, a viscosity modifier, a filler, a coupling agent, an adhesion promoter, and the like.

As the solvent, a solvent which maintains the slurry in a liquid state at room temperature and normal pressure is preferred, and the solvent may include, for example but not limited to, water; alcohols such as methanol, ethanol, propanol, isopropanol, and butyl. Alcohol, isobutanol, secondary butanol, tertiary butanol, pentanol, isoamyl alcohol and hexanol; ketones such as acetone, methyl ethyl ketone, methyl propyl ketone, ethyl propyl ketone, Cyclopentanone, cyclohexanone and cycloheptanone; ethers such as methyl ethyl ether, diethyl ether, dipropyl ether, diisopropyl ether, dibutyl ether, diisobutyl ether, di-n-pentyl ether, diiso Pentyl ether, methyl propyl ether, methyl isopropyl ether, methyl butyl ether, ethyl propyl ether, ethyl isobutyl ether, ethyl n-pentyl ether, ethyl isoamyl ether and tetrahydrofuran Lactones such as γ-butyrolactone and δ-butyrolactone; indoleamines such as β-indoleamine; cycloaliphatic compounds such as cyclopentane, cyclohexane and cycloheptane; aromatic Hydrocarbons such as benzene, toluene, o-xylene, m-xylene, p-xylene, ethylbenzene, propylbenzene, cumene, butylbenzene, isobutylbenzene and n-pentylbenzene; aliphatic hydrocarbons such as heptane, Octane, decane and Alkoxy; acyl chain and cyclic amines, Such as dimethylformamide and N-methylpyrrolidone; esters such as methyl lactate, ethyl lactate, propyl lactate, butyl lactate and methyl benzoate; liquids used to make solvents for the following electrolyte solutions Materials and the like, and in this example, a mixture of about two to five kinds of solvents can be used. For the electrode manufacturing procedure, it is preferred to use a solvent having a boiling point higher than or equal to 80 ° C, preferably higher than or equal to 85 ° C.

The electrically conductive material is a component that further improves the electrical conductivity of the inorganic particles, and may include a content known to those of ordinary skill in the art. If the conductive material has electrical conductivity and does not cause chemical changes in the corresponding battery, the conductive material is not limited to a specific type, and for example, graphite, carbon black, conductive fibers, conductive metal oxide, or the like can be used.

The filler is a supplementary component for suppressing expansion of the electrode, and for example, an olefin-based polymer such as polyethylene and polypropylene; a fibrous material such as glass fiber and carbon fiber, or the like can be used.

The coupling agent is a supplemental component that increases the adhesion strength between the inorganic particles and the organic binder polymer.

The adhesion promoter is an adhesion strength of the inorganic particles in the slurry added to improve the electrode mixture to the current collector, and for example, oxalic acid, adipic acid, or the like can be used.

The slurry of the electrode mixture according to the present invention is applied to an electrode current collector such as an electrode foil, and the current collector can be classified into an anode current collector and a cathode current collector according to the kind of the electrode.

The anode current collector typically has a thickness in the range of 3 to 500 μm. If the anode current collector is electrically conductive, it will not cause a corresponding battery. In the chemical change, the anode current collector is not limited to a special kind, and copper, stainless steel, aluminum, nickel, titanium, sintered carbon, copper or stainless steel treated with carbon, nickel, titanium or silver on the surface may be used, for example. Aluminum-cadmium alloys, etc.

The cathode current collector typically has a thickness in the range of 3 to 500 μm. If the cathode current collector has high conductivity without causing chemical changes in the corresponding battery, the cathode current collector is not limited to a special kind, and may be, for example, stainless steel, aluminum, nickel, titanium, sintered carbon, or surface-treated. Aluminum, stainless steel, etc. treated with carbon, nickel, titanium or silver.

The current collectors may have a fine surface texture which reinforces the bonding strength of the inorganic particles as the active material, and may be used in various shapes such as a film, a sheet, a foil, a mesh, a porous product, a foam, a nonwoven fabric, and the like.

The case also provides separators and electrodes fabricated as described above. The separator and the electrode are formed by inserting the separator between the cathode and the anode, and the lithium secondary battery can be manufactured by injecting a lithium salt-containing nonaqueous electrolyte solution into the electrode assembly.

The lithium salt-containing nonaqueous electrolyte solution includes a nonaqueous electrolyte and a lithium salt. As the non-aqueous electrolyte, a non-aqueous organic solvent, a solid electrolyte, an inorganic solid electrolyte, or the like can be used.

Lithium is a material which is well dissolved in a non-aqueous electrolyte, and 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 can be used.} LiAlCl ₄ , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, (CF ₃ SO ₂ ) ₂ NLi, lithium chloroborate, low carbon aliphatic lithium, lithium tetraphenylborate, ruthenium imine, and the like.

The organic solvent is not limited to a specific kind, and a general organic solvent in the present technology can be used as long as the purpose of the present invention is satisfied.

Further, an additive may be additionally included in the non-aqueous electrolyte, which has characteristics of improving charging and discharging, flame retardancy, and the like.

While the foregoing description is provided by way of example only, the embodiments of the present invention Therefore, it should be clearly understood that the specific examples of the examples disclosed herein are illustrative and are not intended to limit the spirit and scope of the present invention, and the present invention is not limited thereto. It should be understood that the spirit and scope of the case are defined by the scope of the patent application in the Appendix, and the equivalents of the scope of such patent application should be included.

Specific Example 1-1: Manufacture of a slurry of a separator

The slurry was obtained by using 80 g of alumina inorganic particles having a diameter of 500 nm (Nippon Light Metal, LS-235) and 20 g of poly(vinylidene fluoride-hexafluoropropylene) (hereinafter referred to as PVdF-HFP) (Arkema) , LBG2) was obtained by dispersing in 400 g of acetone. The prepared slurry had a viscosity of 38 cP and satisfies Equation 3. The experiment was carried out in triplicate, and the slurry obtained immediately after the experiment is shown in Figure 1a, and the slurry obtained after one day is shown in Figure 1b.

Concrete example 1-2: manufacture of separator

A 16 μm thick polyolefin film (Celgard, C210) was used as the porous polymer substrate, and the slurry obtained immediately after the preparation of Specific Example 1-1 was used. The porous copolymer substrate was coated and then dried to remove the solvent to finally obtain a composite separator. The thickness of the manufactured separator was uniformly measured within 0.5 μm with respect to 26 μm.

Concrete Example 2-1: Manufacture of slurry of separator

The slurry was obtained by using 80 g of soft boehmite inorganic particles (Nabaltec, Actilox 200SM) having a diameter of 200 nm and 20 g of poly(vinylidene fluoride-co-hexafluoropropylene) (hereinafter referred to as PVdF-HFP) (Arkema). , Kynar 2751) was obtained by dispersing in 400 g of acetone. The prepared slurry had a viscosity of 9 cP and satisfies Equation 3.

Concrete example 2-2: manufacture of separator

A 16 μm thick polyolefin film (Celgard, C210) was used as the porous polymer substrate, and the porous copolymer substrate was coated with the slurry obtained immediately after the preparation of Specific Example 2-1, and then dried to remove the solvent to finally obtain a composite separation. Pieces. The thickness of the manufactured separator was uniformly measured within 0.5 μm with respect to 26 μm.

Comparative Example 1-1: Manufacture of slurry of separator

The slurry was obtained in the same manner as in Concrete Example 1-1 but using PVdF-HFP (Arkema, Kynar 2751) having a molecular weight of 287,000. The prepared slurry had a viscosity of 7 cP and did not satisfy Equation 3. The experiment was carried out in triplicate, and the slurry obtained immediately after the experiment is shown in Figure 2a, and the slurry obtained after one day is shown in Figure 2b.

Comparative Example 1-2: Fabrication of separator

A 16 μm thick polyolefin film (Celgard, C210) was used as a porous polymer substrate, and the porous copolymer substrate was coated with a slurry obtained immediately after preparation of Comparative Example 1-1, followed by drying to remove the solvent to finally obtain a composite separation. Pieces. With respect to 26 μm, the thickness of the manufactured separator was unevenly measured in the range of 24 μm to 35 μm, and thus reliable data could not be obtained.

Claims (7)

A slurry for a porous coating of a composite separator, which is composed of inorganic particles, an organic binder polymer and a solvent, wherein the diameter of the inorganic particles is in the range of 0.01 μm to 15 μm, and the solvent is selected From any of the following: acetone, tetrahydrofuran, dichloromethane, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP) and cyclohexane, or a mixture thereof, according to 100 The content of the inorganic particles is 10 to 50 parts by weight, and the content of the organic binder polymer is 1 to 10 parts by weight, and the lower limit of the viscosity of the slurry is based on the inorganic particles. The value obtained from the equation shown below, and the upper limit of viscosity is 10,000 cP: Where η represents the viscosity of the slurry (in centipoise (cP)), and d represents the average diameter (in μm) of the inorganic particles. The slurry of claim 1, wherein the inorganic particles are selected from the group consisting of inorganic particles having a dielectric constant greater than or equal to 5, inorganic particles having lithium ion transporting ability, and a mixture of such. A slurry according to claim 2, wherein the inorganic particles having a dielectric constant greater than or equal to 5 are selected from any one of the group consisting of BaTiO ₃ , Pb (Zr _x , Ti _{1 ) -x} )O ₃ (PZT, 0<x<1), Pb _1-x La _x Zr _1-y Ti _y O ₃ (PLZT, 0<x<1, 0<y<1), (1-x) Pb(Mg _1/3 Nb _2/3 )O _3-x PbTiO ₃ (PMN-PT, 0<x<1), yttrium oxide (HfO ₂ ), SrTiO ₃ , SnO ₂ , CeO ₂ , MgO, NiO, CaO , ZnO, ZrO ₂ , SiO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , SiC and TiO ₂ , or a mixture thereof. A slurry according to claim 2, wherein the inorganic particles having lithium ion transporting ability are selected from any one of the group consisting of lithium phosphate (Li ₃ PO ₄ ), lithium titanium phosphate (Li) _x Ti _y (PO ₄ ) ₃ , 0 < x < 2, 0 < y < 3), lithium aluminum phosphate (Li _x Al _y Ti _z (PO ₄ ) ₃ , 0 < x < 2, 0 < y < 1 , 0<z<3), glass with (LiAlTiP) _x O _y as the substrate (0<x<4, 0<y<13), lithium tantalate strontium (Li _x La _y TiO ₃ , 0<x<2,0<y<3), lithium sulphate bismuth (Li _x Ge _y P _z S _w , 0<x<4, 0<y<1, 0<z<1, 0<w<5), nitridation Lithium (Li _x N _y , 0<x<4, 0<y<2), with SiS ₂ (Li _x Si _y S _z , 0<x<3, 0<y<2, 0<z<4) a glass of a substrate and a glass having a basis of P ₂ S ₅ (Li _x P _y S _z , 0<x<3, 0<y<3, 0<z<7), or a mixture thereof. The slurry of claim 1, wherein the organic binder polymer is selected from any one of the group consisting of polyvinylidene fluoride (PVdF) as a base material, Polyvinylidene fluoride-co-trichloroethylene, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, polyethylene-co-vinyl acetate, polyethylene oxide, acetic acid Cellulose, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl polytriglucose, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, polytriglucose (pullulan), carboxymethyl Cellulose, An acrylonitrile-styrene-butadiene copolymer, and a polyimine, or a mixture thereof. A composite separator for an electrochemical device, which is produced using a slurry as claimed in any one of claims 1 to 5. An electrochemical device comprising a cathode, an anode, and a separator interposed between the cathode and the anode, wherein the separator is produced using the slurry of any one of claims 1 to 5.