KR101130052B1 - Sheet-typed Separator Containing Mixed Coating Layer and Electrochemical Cell Employed with the Same - Google Patents

Abstract

The present invention is a sheet-type separator having a porous structure capable of moving ions while maintaining the insulation state of the electrodes facing each other on both sides, at least one side of the separator is a mixed coating layer containing an inorganic component, a binder component and a lithium salt Is formed, to provide a separator, characterized in that to improve the conductivity of lithium ions while increasing the thermal safety and mechanical strength.

Since the separator according to the present invention contains an inorganic component, the thermal and mechanical strength are increased, and the lithium salt may be dissolved in the electrolyte, and thus the ion conductivity may be significantly improved. Accordingly, when the separator is applied to a battery or the like, an electrochemical cell having excellent stability and output characteristics due to external force can be manufactured without increasing resistance.

Description

Sheet-type separator comprising mixed coating layer and electrochemical cell using same {Sheet-typed Separator Containing Mixed Coating Layer and Electrochemical Cell Employed with the Same}

The present invention relates to a sheet-type separator comprising a mixed coating layer and an electrochemical cell using the same, and more particularly, a sheet-type separator having a porous structure capable of moving ions while maintaining the insulation state of the electrodes facing each other on both sides As at least one surface of the separator, a mixed coating layer including an inorganic component, a binder component, and a lithium salt is formed, thereby improving a thermal stability and mechanical strength while improving the conductivity of lithium ions, and including the same. It provides an electrochemical cell consisting of.

As technology development and demand for mobile devices are increasing, the demand for batteries as energy sources is rapidly increasing, and accordingly, a lot of researches on batteries capable of meeting various demands have been conducted.

BACKGROUND ART [0002] In recent years, rechargeable secondary batteries have been widely used as energy sources for wireless mobile devices. In addition, secondary batteries are attracting attention as energy sources such as electric vehicles and hybrid electric vehicles, which are proposed as a way to solve air pollution of conventional gasoline and diesel vehicles using fossil fuel. Therefore, the application field using the secondary battery is becoming very diversified due to the advantages of the secondary battery, and it is expected that the secondary battery will be applied to many fields and products in the future.

As the application fields and products of secondary batteries are diversified as described above, the types of batteries are also diversified to provide outputs and capacities suitable for them. In addition, batteries applied to the art and products are strongly required for small size and light weight. Small mobile devices such as cell phones, PDAs, digital cameras, and notebook computers have one or two or three small and light battery cells per device, corresponding to the miniaturization tendency of the products.

On the other hand, medium and large devices such as electric bicycles, electric motorcycles, electric vehicles, hybrid electric vehicles, etc., due to the necessity of high output capacity, medium and large battery modules (or medium and large battery packs) electrically connecting a plurality of battery cells are used. Since the size and weight of the battery module are directly related to the accommodation space and output of the medium and large devices, manufacturers are trying to manufacture a battery module that is as small and lightweight as possible. In addition, devices that receive a lot of shocks and vibrations from the outside, such as electric bicycles and electric vehicles, should have a stable electrical connection state and physical coupling state between the elements constituting the battery module. Safety aspects are also important because they must be implemented.

In terms of the shape of the battery, there is a high demand for square secondary batteries and pouch type secondary batteries that can be applied to products such as mobile phones with a thin thickness, and in terms of materials, lithium ion batteries with high energy density, discharge voltage and output stability, and lithium There is a high demand for lithium secondary batteries such as ion polymer batteries.

A 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, a polyolefin-based porous separator between a cathode and an anode, and a nonaqueous electrolyte containing lithium salt such as LiPF ₆ . Done. During charging, lithium ions of the positive electrode active material are released and inserted into the carbon layer of the negative electrode, and during discharge, lithium ions of the negative electrode carbon layer are released and inserted into the positive electrode active material, wherein the non-aqueous electrolyte solution is lithium ions between the negative electrode and the positive electrode. It acts as a medium for moving the. In such a lithium secondary battery, charging and discharging proceed while repeating a process in which lithium ions of a positive electrode are intercalated and deintercalated into a negative electrode.

The electrode assembly composed of the anode / separator / cathode may be simply a stacked structure, but a plurality of electrodes (anode and cathode) may be laminated in a state where a separator is interposed therebetween and then bonded to each other by heating / pressurization. It may be. In this case, bonding of the electrode and the separator is achieved by heating / pressurizing the adhesive layer formed on the separator and the electrode in a state facing each other.

In general, a binder material may be coated on the separator in order to improve adhesion with an electrode. In addition, by adding a separate inorganic component to increase the mechanical strength of the separator, it is possible to ensure the safety of the battery by external force or the like. In this regard, the present applicant has proposed a technology including an active layer coated with a mixture of inorganic particles and a binder polymer on a separator substrate in Korean Patent Application Publication No. 2006-0072065. The separator is connected and fixed between the inorganic particles due to the binder polymer on the separator substrate, and forms a heat resistant pore structure due to the interstitial volume between the inorganic particles, thereby simultaneously improving the electrochemical safety and performance of the battery. It works.

However, when a separator coated with a binder material or a composite of an inorganic material and a binder is used in an electrochemical cell such as a battery, a problem of increasing resistance of the battery occurs. When the internal resistance increases, the output characteristics of the battery deteriorate, and as the charge and discharge cycle proceeds, the capacity decreases rapidly and the cycle life is shortened.

Therefore, in the electrochemical cell, the adhesion to the electrode is improved by coating a binder and / or inorganic particles on the separator, thereby improving the mechanical strength of the separator, but not increasing the internal resistance, thereby providing a separator having excellent output characteristics. There is a high need for it.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems of the prior art and the technical problems required from the past.

After extensive research and various experiments, the inventors of the present application form a mixed coating layer including an inorganic component, a binder component, and a lithium salt on at least one surface of a separator to improve the conductivity of lithium ions while increasing mechanical strength. It was confirmed that it is possible to improve the thermal safety and output characteristics of the electrochemical cell comprising the same, and came to complete the present invention.

Accordingly, the present invention is a sheet-type separator having a porous structure capable of moving ions while maintaining the insulating state of the electrodes facing each other on both sides, at least one surface of the separator containing an inorganic component, a binder component and a lithium salt The mixed coating layer is formed to provide a separator, characterized in that to improve the conductivity of lithium ions while increasing safety and mechanical strength.

In the separator according to the present invention, as the lithium salt contained in the mixed coating layer is eluted into the electrolyte, fine pores are formed at the place where the lithium salt is present, thereby improving ionic conductivity. In addition, since the inorganic component and the binder component are included, it is possible to prevent the deformation and shrinkage of the separator in an external force or a high temperature environment, thereby maintaining excellent thermal conductivity while maintaining thermal and mechanical strength.

Therefore, when the separator according to the present invention is applied to an electrochemical cell such as a lithium secondary battery, the binder is included for improving adhesion to the electrode and an inorganic component for improving the mechanical strength of the separator is included in the coating layer. The increase in internal resistance is not caused by the elution of the lithium salt, which ultimately ensures the stability of the electrochemical cell, while also significantly improving the output characteristics.

Lithium salt eluted from the separator flows into the electrolyte and contributes to the charge and discharge of the electrochemical cell, and thus does not cause any side reactions. Rather, when lithium salts are eluted slowly over a long period of time, or the remaining lithium salts are eluted slowly after a large number of lithium salts are initially eluted, they may serve to replenish electrolytes consumed during continuous charge and discharge processes. .

Such lithium salts may be substantially the same contained in the electrolyte of the lithium secondary battery, 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, and lithium tetraphenyl borate It may be one or two or more selected from the group consisting of.

The inorganic component does not cause an oxidation and / or reduction reaction, that is, an electrochemical reaction with the positive or negative electrode current collector in the operating voltage range of the battery (for example, 0 to 5 V on Li / Li ⁺ basis) and does not impair conduction. Not particularly limited, for example, BaTiO 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 ), SrTiO ₃ , SnO ₂ , CeO ₂ , MgO, NiO, CaO, ZnO, ZrO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , and TiO ₂ It may be one or two or more selected from the group consisting of.

The binder is not particularly limited as long as it is a component that is not easily dissolved by an electrolyte while exhibiting a bonding force with an electrode laminated on the separator and an inorganic component and lithium salts in the mixed coating layer. For example, polyvinylidene fluoride (PVdF), polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-co-trichloroethylene, Polyvinylidene fluoride-chlorotrifluoroethylene (PVdF-CTFE), polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate , Ethylene vinyl co-vinyl acetate, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, Cyanoethylpullulan, cyanoethylpolyvinyla lcohol, cyanoethyl cellulose, cyanoethylsucrose, pullulan, carboxyl methyl cellulose, acrylonitrile-styrene-butadiene copolymer ), And polyimide may be one or a mixture of two or more, preferably PVdF or PVdF-CTFE.

As the sheet-type separator, an insulating thin film which prevents internal short circuit between the anode and the cathode and has high ion permeability and mechanical strength is used. The pore diameter of the separator is generally from 0.01 to 10 ㎛ ㎛, thickness is generally 5 ~ 300 ㎛.

The material of the separator is not particularly limited, and a known separator may be used as it is. For example, a sheet or a nonwoven fabric made of a polyolefin-based film such as polypropylene having excellent chemical resistance and hydrophobicity, glass fiber or polyolefin, or the like may be used. Used. Typical examples on the market include Celgard series (Celgard ^TM 2400, 2300 (manufactured by Hoechest Celanese Corp.), polypropylene membrane (manufactured by Ube Industries Ltd. or Pall RAI), and polyethylene series (Tonen or Entek)). Can be used, but is not limited to these.

If the concentration of the lithium salt in the coating layer is too low, it is difficult to exert the effect of the addition, while if the concentration is too high, the content of the binder or inorganic components is relatively reduced to exhibit a certain mechanical strength, or the adhesion between the electrode and the separator is There is a problem because lithium metal may precipitate at the interface between the electrode and the separator. In consideration of this point, the concentration of the lithium salt is preferably 0.1 to 10% by weight based on the total weight of the coating layer. More preferred content is 0.5 to 5% by weight.

The concentration of the inorganic component is preferably 60 to 90% by weight based on the weight of the coating layer. If the concentration of the inorganic component is too low, the desired mechanical strength and thermal stability cannot be maintained, and conversely, the concentration of the inorganic component If too high, the porosity of the separator cannot be secured due to the excess inorganic component, and thus the ion resistance may be lowered, thereby increasing the internal resistance.

On the other hand, the inorganic component may be in the form of particles, the particle size of the particles is preferably 0.001 to 10 ㎛ bar, if the particle size of the inorganic component particles is too small, the dispersibility of the particles may be rather hindered the movement of ions On the contrary, if the particle size is too large, the thickness of the separator may be increased, and thus the battery capacity may be relatively decreased, thereby causing a problem.

As defined above, the separator according to the present invention may improve conductivity of lithium ions by eluting lithium salts while increasing thermal safety and mechanical strength through formation of a mixed coating layer including an inorganic component, a binder component, and a lithium salt. have.

It is preferable that the thickness of the mixed coating layer is 2 to 5 μm. If the thickness of the mixed coating layer is too thin, it is difficult to exert an effect of improving the desired mechanical strength and ionic conductivity. On the contrary, if the thickness of the mixed coating layer is too thick, the mixed coating layer may act as a resistance layer. So there is a problem.

The method of coating the mixed coating layer on the surface of the separator is not particularly limited. For example, it may be formed by various methods such as flow coating, spin coating, dip coating, bar coating, and the like, and preferably a separation membrane. The sheet may be dipped in a mixed solution in which a binder, an inorganic component and a lithium salt are dispersed to form a coating layer.

The present invention also relates to a slurry for coating on at least one surface of a sheet-type separator having a porous structure capable of moving ions while maintaining the insulation state of electrodes facing each other on both sides, including an inorganic component, a binder component, and a lithium salt. It provides a slurry for membrane coating, characterized in that.

When the separator is coated using the slurry for coating the separator according to the present invention, not only the thermal and mechanical strength of the separator may be maintained, but also as described above, fine pores corresponding to the size of the lithium salt may be formed by elution of the lithium salt. As can be seen, it is possible to improve the ion transport capacity of the membrane.

The present invention also provides an electrochemical cell consisting of an electrode assembly wherein the porous separator is interposed between an anode and a cathode, the electrochemical cell provides electricity through an electrochemical reaction, for example For example, it may be an electrochemical secondary battery or an electrochemical capacitor.

In particular, the present invention may be preferably applied to a lithium secondary battery prepared by injecting a lithium electrolyte in a state in which the electrode assembly is mounted inside the battery case. In addition, the secondary battery may be used in the manufacture of a high output large capacity battery pack, preferably in combination with a plurality of unit cells.

Since high power large capacity battery packs are frequently subjected to external forces such as vibration and external shocks, excellent mechanical strength is required for external forces, and the amount of electrode active material loaded on the current collector is high and high rate in the structure of the battery cells constituting the battery pack. Since charge and discharge characteristics are required, the cycle characteristics and the output characteristics may act as important factors in order to exhibit predetermined operating characteristics. In this respect, the electrochemical cell of the present invention can be preferably used as a unit cell in a battery pack of high output large capacity.

Other components of the lithium secondary battery as a preferred example of the electrochemical cell according to the present invention will be described below.

The positive electrode for a lithium secondary battery is prepared by, for example, applying a mixture of a positive electrode active material, a conductive material, and a binder in the form of a slurry on a positive electrode current collector, followed by drying and compressing the filler. Other components such as modulators, crosslinking promoters, coupling agents, adhesion promoters and the like may optionally be further included or in combination of two or more.

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 , LiMnO _2, and the like; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ , Cu ₂ V ₂ O ₇ and the like; Ni-site type lithium nickel oxide represented by the formula LiNi _{1- x} M _x O ₂ , wherein M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, and x = 0.01 to 0.3; Formula LiMn _{2 - x} M _x O ₂ (wherein M = Co, Ni, Fe, Cr, Zn or Ta and x = 0.01 to 0.1) or Li ₂ Mn ₃ MO ₈ (wherein M = Fe, Co, Lithium manganese composite oxide represented by Ni, Cu or Zn); LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with alkaline earth metal ions; 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. For example, the surface of stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel Surface treated with carbon, nickel, titanium, silver, or the like can be used. The current collector may form fine irregularities on its surface to increase the adhesion of the positive electrode active material, and may be in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric.

The conductive material is typically added in an amount of 1 to 50% by weight based on the total weight of the mixture including the positive electrode active material. Such a conductive material is not particularly limited as long as it has conductivity without causing chemical change in the battery, and examples thereof include graphite such as natural graphite and artificial graphite; Carbon blacks 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 powder, aluminum powder and nickel powder; Conductive whiskeys 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 that assists in bonding the active material and the conductive material to the current collector, and is generally added in an amount of 1 to 50 wt% based on the total weight of the mixture including the positive electrode active material. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene , Polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butylene rubber, fluorine rubber, various copolymers 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 viscosity modifier is a component that adjusts the viscosity of the electrode mixture so that the mixing process of the electrode mixture and the coating process on the current collector thereof can be easily added, it may be added in 0 to 30% by weight based on the total weight of the electrode mixture. Examples of such viscosity modifiers include carboxymethyl cellulose, polyvinylidene fluoride, polyvinyl alcohol, and the like, but are not limited thereto. In some cases, a solvent such as N-methyl pyrrolidon (NMP) may be used in an amount of 0 to 30% by weight based on the total weight of the electrode mixture to adjust the viscosity. It is dried to prepare a negative electrode.

The crosslinking accelerator may be added in an amount of 0 to 50% by weight based on the weight of the binder as a material for promoting crosslinking of the binder. As such a crosslinking accelerator, amines such as diethylene triamine, triethylene tetramine, diethylamino propylamine, xylene diamine, and isophorone diamine , Acid anhydrides such as dodecyl succinic anhydride, phthalic anhydride and the like can be used. In addition, polyamide resin, polyselphite resin, phenol resin, or the like may be used.

The coupling agent is a material for increasing the adhesion between the active material and the binder, characterized in that it has two or more functional groups, it can be added in 0 to 30% by weight based on the weight of the binder. One functional group reacts with a hydroxyl group or a carboxyl group on the surface of a silicon, tin, or graphite-based active material to form a chemical bond, and the other functional group is a material that forms a chemical bond through reaction with a nanocomposite according to the present invention. It is not specifically limited, For example, triethoxy silylpropyltetrasulfide, mercaptopropyl triethoxysilane, aminopropyl triethoxysilane, chloropropyl trie Chloropropyl triethoxysilane, vinyl triethoxysilane, methacryloxypropyl triethoxysilane, glycidoxypropyl triethoxysilane, isocyanatepropyl triethoxysilane, cyanatopropyl triethoxysilane (cyan Silane-based coupling agents such as atopropyl triethoxysilane) may be used.

The adhesion promoter may be added in an amount of 10% by weight or less relative to the binder, and is not particularly limited as long as it is a material for improving adhesion of the electrode active material to the current collector. For example, oxalic acid, adipic acid ( adipic acid), formic acid, formic acid derivatives, itaconic acid derivatives, and the like.

The negative electrode is manufactured by applying and drying a negative electrode material on the negative electrode current collector, and if necessary, the components as described above may be further included.

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 current collector, fine concavities and convexities may be formed on the surface to enhance the bonding strength of the negative electrode active material, and may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric.

The negative electrode material may be, for example, carbon such as hardly 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 ≦ 1; 1 ≦ y ≦ 3; 1 ≦ z ≦ 8); Lithium metal; Lithium alloys; Silicon-based alloys; Tin-based alloys; 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 metal oxides such as Bi ₂ O ₅ ; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials and the like can be used.

The non-aqueous electrolyte for lithium secondary batteries consists of a nonaqueous electrolyte and a lithium salt. As the non-aqueous electrolyte, a non-aqueous electrolyte, a solid electrolyte, an inorganic solid electrolyte and the like are used. As described above, the lithium salt may be the same as the lithium salt included in the coating layer of the separator.

Examples of the nonaqueous electrolytic solution include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, But are not limited to, lactone, 1,2-dimethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, Nitrile, nitromethane, methyl formate, methyl acetate, phosphoric acid triester, trimethoxymethane, dioxolane derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives , Tetrahydrofuran derivatives, ether, methyl pyrophosphate, ethyl propionate and the like can be used.

Examples of the organic solid electrolytes include polyethylene derivatives, polyethylene oxide side derivatives, polypropylene oxide derivatives, phosphate ester polymers, agitation lysine, polyester sulfides, polyvinyl alcohols, and polyvinylidene fluorides. , Polymers containing ionic dissociating 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, sulfates and the like of Li, such as Li ₄ SiO ₄ -LiI-LiOH, Li ₃ PO ₄ -Li ₂ S-SiS ₂ , and the like, may be used.

In addition, for the purpose of improving charge / discharge characteristics, flame retardancy, etc., for example, pyridine, triethyl phosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyme, hexaphosphate triamide, etc. Nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N, N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrroles, 2-methoxy ethanol, aluminum trichloride, etc. It may be. In some cases, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride may be further added to impart nonflammability, or a carbon dioxide gas may be further added to improve high-temperature storage characteristics.

As described above, the separator according to the present invention contains a lithium salt while increasing the thermal and mechanical strength of the separator by an inorganic component to effectively prevent deformation of the separator, and thus, lithium salt is contained by elution of the lithium salt. Ion conductivity of the separator may be improved by the minute pores formed in the site. Therefore, when the separator according to the present invention is applied to an electrochemical cell such as a secondary battery, an electrochemical cell having excellent stability and output characteristics due to external force can be manufactured without increasing internal resistance.

Those skilled in the art to which the present invention pertains will be able to make various applications and modifications within the scope of the present invention based on the above contents.

Claims (14)

A sheet-type separator having a porous structure capable of moving ions while maintaining the insulation state of electrodes facing each other on both sides includes an electrode assembly interposed between an anode and a cathode, and a non-aqueous electrolyte. A mixed coating layer including an inorganic component, a binder component, and a lithium salt is formed on at least one surface of the separator, thereby improving thermal conductivity and mechanical strength while improving conductivity of lithium ions. The non-aqueous electrolyte lithium secondary battery comprising a non-aqueous electrolyte and a lithium salt. According to claim 1, The lithium salt of the coating layer is 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 lithium carboxylate, and one or more selected from the group consisting of lithium phenyl borate Lithium secondary battery. The inorganic component of claim 1, wherein the inorganic component is BaTiO 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 ) SrTiO ₃ , SnO ₂ , CeO ₂ , MgO, NiO, CaO, ZnO, ZrO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , and TiO ₂ Lithium secondary battery, characterized in that one or two or more selected from the group consisting of. The method of claim 1, wherein the binder component is polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-trichloroethylene, polyvinylidene fluoride-chlorotrifluoroethylene, poly Methyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, ethylene vinyl acetate copolymer, polyethylene oxide, cellulose acetate, cellulose acetate butylate, cellulose acetate propionate, cyanoethyl pullulan, cya Lithium, characterized in that one or two or more selected from the group consisting of noethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, carboxymethyl cellulose, acryronitrile styrenebutadiene copolymer, and polyimide Secondary battery. The lithium secondary battery according to claim 1, wherein the separator is a polyolefin-based film or a sheet or nonwoven fabric made of glass fiber or polyolefin. According to claim 1, wherein the lithium salt of the coating layer is a lithium secondary battery, characterized in that contained in a concentration of 0.1 to 10% by weight based on the weight of the coating layer. The lithium secondary battery of claim 1, wherein the inorganic component is included in a concentration of 60 to 90 wt% based on the weight of the coating layer. The lithium secondary battery of claim 1, wherein the mixed coating layer has a thickness of 2 μm to 5 μm. The lithium secondary battery of claim 1, wherein the mixed coating layer is coated by a dip coating method. delete delete delete delete The lithium secondary battery of claim 1, wherein the lithium secondary battery is used as a unit cell in a battery pack having a high output capacity.