KR20120111287A - Apparatus for preparing for separator and preparing method using it - Google Patents

Abstract

PURPOSE: An apparatus and method for preparing a separator is provided to prevent thermal deformation of a separator, to collect solvent and to accept various solvents by using a non-heating type drying method. CONSTITUTION: An apparatus(100) for preparing a separator comprises a porous substrate supply unit(120) supplying a planar porous substrate(110), a coating unit arranged on a first side of the porous substrate and coating the first plane of the porous substrate with slurry comprising a mixture of a binder polymer and solvent, and solvent removal units(140,150) arranged on a second side of the porous substrate and removing the solvent from the porous substrate coated with the slurry by using pressure difference between the first side and the second side.

Description

Apparatus for preparing for separator and preparing method using it}

The present invention relates to a manufacturing apparatus for a separator having a porous coating layer and a method for manufacturing the same, and to a manufacturing apparatus for removing a solvent of the porous coating layer and a method thereof.

Recently, as the interest in energy storage technology is increasing, the field of application is expanding to mobile phones, camcorders, notebook PCs, and even electric vehicles, and efforts for research and development of electrochemical devices related thereto are becoming more and more specific. The electrochemical device is the most attracting field in this respect, and the development of a secondary battery capable of charging and discharging has been the focus of attention, and in recent years in the development of such a battery, research to improve the capacity density and specific energy Development is in progress.

Among the secondary batteries currently applied, lithium secondary batteries developed in the early 1990s have higher operating voltage and significantly higher energy density than conventional batteries such as Ni-MH, Ni-Cd, and sulfuric acid-lead batteries that use an aqueous electrolyte solution. It is attracting attention as an advantage. However, such a lithium ion battery has safety problems such as ignition and explosion due to the use of an organic electrolyte, and has a disadvantage in that the manufacturing process is difficult. Recently, the lithium ion polymer battery has been considered as one of the next generation batteries by improving the weakness of the lithium ion battery, but the capacity of the battery is still relatively lower than that of the lithium ion battery, and the discharge capacity is improved due to insufficient discharge capacity at low temperatures. This is urgently needed.

The safety characteristics of the electrochemical devices as described above are different from each other. The most important consideration with regard to the safety of these electrochemical devices is that the electrochemical devices should not cause injury to the user in case of malfunction. For this purpose, the safety standard strictly regulates the ignition and smoke in the electrochemical devices. In the safety characteristics of the electrochemical device, there is a high possibility that an explosion occurs when the electrochemical device is overheated to cause thermal runaway or the separator penetrates. In particular, polyolefin-based porous substrates commonly used as separators for electrochemical devices exhibit extreme heat shrinkage behavior at temperatures of 100 degrees or more due to material characteristics and manufacturing process characteristics including stretching, and thus, a short circuit between the anode and the cathode. Will cause. In order to solve the safety problem of the electrochemical device, Korean Patent Publication No. 10-2007-231 discloses a porous organic material formed by coating a mixture of inorganic particles and a binder polymer on at least one surface of a porous substrate having a plurality of pores A separator having an inorganic coating layer has been proposed.

In general, in the manufacturing process of such a separator, a slurry containing a mixture of inorganic particles and a binder polymer is coated on a surface of the porous substrate and thermally dried to form an organic-inorganic coating layer. Since the deformation of the substrate may occur, and the heat-drying temperature may not exceed the temperature at which the deformation of the porous substrate does not occur, the solvent that can be used is limited, so that the selection of the solvent for improving the physical properties of the separator is limited. have.

The present invention has been conceived to solve the above problems, and to provide a method and apparatus for manufacturing a separator that does not require a heat-drying process as a technical problem.

In order to solve the above problems, the apparatus for manufacturing a separator according to an exemplary embodiment of the present invention, porous substrate supply means for supplying a porous substrate of the plane; Coating means disposed on a first side of the porous substrate to be supplied, and coating the first side of the porous substrate with a slurry including a mixture of inorganic particles, a binder polymer, and a solvent; It is disposed on the second side of the porous substrate, and the solvent removing means for absorbing and removing the solvent from the slurry-coated porous substrate using the pressure difference between the first surface and the second surface.

The separator manufacturing apparatus may further include a solvent removing fluid supply means disposed on a first surface of the porous substrate facing the solvent removing means and supplying a solvent removing fluid to pass through the porous substrate coated with a slurry. Can be. In addition, the solvent removing fluid may be air, nitrogen, argon, helium or carbon dioxide, but is not limited thereto.

The coating means may use a coating apparatus having a slot die, but is not limited thereto.

The solvent removing means comprises a porous endless belt traveling in contact with the second surface of the porous substrate; A driving unit for driving the porous endless belt; And a suction part positioned inside the porous endless belt and generating a pressure difference between the first surface and the second surface to absorb and remove the solvent.

In addition, the solvent removing means, the solvent removing means is a hollow cylindrical porous roll driven in contact with the second surface of the porous substrate; A guide roll disposed to face the porous roll and being in contact with the first surface; And a suction part disposed in the porous roll to absorb and remove the solvent by generating a pressure difference between the first surface and the second surface.

Examples of the porous substrate of the present invention include a polyethylene film including a fine pore, a polypropylene film, or a multilayer film prepared by a combination of these films, and polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, or poly Polymer films of vinylidene fluoride hexafluoropropylene copolymers and the like can be used.

In addition, as the inorganic particles of the present invention, inorganic particles having a dielectric constant of 5 or more, inorganic particles selected from the group consisting of inorganic particles having lithium ion transfer ability, and mixtures thereof may be used. Inorganic particles having a dielectric constant of 5 or more include 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 -xPbTiO 3 (PMN-PT, 0 <x <1), hafnia (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, TiO ₂ , and the like can be used. In addition, the inorganic particles having the lithium ion transfer ability include lithium phosphate (Li ₃ PO ₄ ), lithium titanium phosphate (Li _x Ti _y (PO ₄ ) ₃ , 0 <x <2, 0 <y <3), and 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 series glass (0 <x <4, 0 <y <13), lithium lanthanum titanate (Li _x La _y TiO ₃ , 0 <x <2, 0 <y <3), lithium germanium thiophosphate (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), SiS ₂ (Li _x Si _y S _z , 0 <x <3, 0 <y <2, 0 <z <4) Series glass and P ₂ S ₅ (Li _x P _y S _z , 0 <x <3, 0 <y <3, 0 <z <7) series glass etc. can be used.

It is preferable to use a weight ratio of the inorganic particles and the binder polymer is 50:50 to 99: 1.

Examples of the binder polymer of the present invention include polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-co-trichloroethylene, and polymethyl methacrylate. (polymethylmethacrylate), polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, ethylene vinyl acetate copolymer (polyethylene-co-vinyl acetate), Polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan , Cyanoethyl polyvinyl alcohol (c yanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan and carboxyl methyl cellulose can be used.

The solvent is not particularly limited in its kind but may be acetone, methyl ethyl ketone (MEK), toluene, ethyl acetate, butyl acetate, methanol, ethanol, isopropyl alcohol, water, hexane, cyclohexane Dimethyl formamide (DMF), dimethyl acetamide (DMAc), N-methyl-2-pyrrolidone (NMP) and mixtures of these solvents can be used. have.

The method of manufacturing a separator of the present invention comprises the steps of: coating the first surface of the porous substrate of the planar surface supplied with a slurry comprising a mixture of inorganic particles, a binder polymer and a solvent; And generating a pressure difference between the first side and the second side of the porous substrate, thereby absorbing and removing the solvent through the second side of the slurry coated porous substrate.

In addition, in the method of manufacturing the separator, in the step of removing the solvent, the solvent removal fluid may be supplied to pass through the porous substrate on the first side.

As the solvent removing fluid, air air, nitrogen, argon, helium or carbon dioxide may be used.

The separator manufactured by the manufacturing method of the present invention may be used in an electrochemical device including a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and is particularly suitable for a lithium secondary battery.

The present invention, which is an apparatus and a method for manufacturing a separator having a porous coating layer that is dried by coating a slurry including a mixture of inorganic particles, a binder polymer, and a solvent, has a low possibility of thermal deformation of the separator during the manufacturing process. In addition, since there is no fear that the separator is thermally deformed, a solvent having a low volatility or a solvent having a high boiling point can be used. And, the removed solvent is environmentally friendly because it can be recovered and recycled.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments of the invention and, together with the description of the invention, It should not be construed as limited.
1 is a view schematically showing the configuration of a separator manufacturing apparatus having a belt-type solvent removing apparatus according to an embodiment.
2 is a view schematically illustrating a configuration of a separator manufacturing apparatus having a belt-type solvent removing device and a solvent removing fluid supply device according to an embodiment.
3 is a view schematically showing the configuration of a separator manufacturing apparatus having a roll-type solvent removing device according to an embodiment.

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

1 is a view schematically showing a configuration of a separator manufacturing apparatus having a belt-type solvent removing apparatus according to an embodiment, Figure 2 is a belt-type solvent removing apparatus and a solvent removing fluid supply apparatus according to an embodiment It is a figure which shows schematically the structure of one separator manufacturing apparatus. 3 is a diagram schematically illustrating a configuration of a separator manufacturing apparatus having a roll-type solvent removing device according to an embodiment.

Referring first to Figure 1, the manufacturing apparatus 100 of the present invention comprises a porous substrate supply means 120 for supplying a planar porous substrate 110; Coating means (130) disposed on the first surface of the supplied porous substrate and coating the first surface of the porous substrate with a slurry including a mixture of inorganic particles, a binder polymer, and a solvent; Is disposed on the second side of the porous substrate, and the solvent removing means 140, 150 for removing the solvent from the slurry-coated porous substrate by using the pressure difference between the first surface and the second surface. .

In general, the porous substrate is wound and provided on a roll for ease of transportation, ease of processing, and the like, and is supplied to the apparatus for manufacturing a separator using the porous substrate wound on the roll. In this case, the porous substrate may be supplied to travel while maintaining a constant speed by using the guide roll 120 to maintain a constant tension.

 The coating means 130 may be disposed on the first surface (upper surface) of the porous substrate 110. For the single-side coating, the slot die 130 may be used as shown in FIG. The slurry used for the coating may include a mixture of inorganic particles, a binder polymer and a solvent. This slurry is thinly applied to the first surface of the porous substrate 110 through the slot die 130.

Since the slurry contains a solvent, it must go through a process for removing such a solvent. Conventionally, it was dried using hot air in an oven. When using an olefin film such as a typical polyethylene film used as a porous substrate, only a relatively low temperature hot air could be used due to fear of deformation by heat. Accordingly, the solvents that can be used are limited to solvents having high volatility or low boiling point that are easy to dry. However, in the present invention, since the non-heating drying method is used, a solvent having a high volatility can also be used. In the present invention, the solvent is removed from the coated slurry by using the difference in pressure between the first and second surfaces (lower side) of the porous substrate coated with the slurry. The devices 140 and 150 are operated to lower the pressure on the second side of the porous substrate, and the pressure difference causes the solvent contained in the slurry coated on the first side to pass through the porous substrate 110 to Suction is removed by the solvent removal apparatuses 140 and 150 arranged. In addition, the solvent is removed by passing through the porous substrate 110, it is possible to prevent the detachment of the inorganic particles that may occur during the drying process. Alternatively, the solvent may be removed by heating the slurry to a constant temperature to increase the efficiency of solvent drying.

Referring to FIG. 2, the separator manufacturing apparatus 200 of the present invention is disposed on the first surface of the porous substrate 210 opposite to the solvent removing means 240 and 250 so that the slurry passes through the coated porous substrate. Solvent removal fluid supply means 260 for supplying a solvent removal fluid may be further provided. These solvent removal fluids maintain a high density and pass through the slurry coated on the surface of the porous substrate 210, and also maintain the pressure difference between the first and second surfaces to facilitate the removal of the solvent. As the solvent removal fluid, air, nitrogen, argon, helium and carbon dioxide may be used. In addition, in order to increase the efficiency of solvent removal, the solvent removal fluid may be heated and used at a constant temperature.

A suction belt may be used as the solvent removing means, which will be described in more detail with reference to FIG. 1. The solvent removing means 140 and 150 may be in contact with a second surface of the porous substrate 110. Porous endless belt 140; A driving unit for driving the porous endless belt; And a suction unit 150 positioned inside the porous endless belt and generating a pressure difference between the first surface and the second surface to absorb and remove the solvent. The porous endless belt 140 is partially in contact with the second surface of the porous substrate and is constantly circulated by the driving of the drive unit. The porous endless belt prevents damage such as stretching or tearing of the porous substrate 110 due to excessive pressure difference. The suction unit 250 is located inside the porous endless belt 140, and generates a pressure difference between the first surface and the second surface of the porous substrate 110 by a driving principle similar to a vacuum cleaner. Absorb the solvent and remove it.

Another solvent removal means may be a suction roll. A more detailed look with reference to FIG. 3 shows that the solvent removal means 300 is the solvent removal means of the porous substrate 310. A hollow cylindrical porous roll 360 in contact with two surfaces and driven; A guide roll 380 disposed to face the porous roll and being in contact with the first surface; And a suction part 370 positioned in the porous roll to absorb and remove the solvent by generating a pressure difference between the first surface and the second surface. The porous roll 360 has a hollow cylindrical structure and is in contact with the second surface of the porous substrate 310 and driven at the same speed as the traveling speed of the porous substrate. In addition, the guide roll 380 is disposed to face the first surface such that the porous substrate 310 closely contacts the porous roll 360. The suction part 370 having an operating principle similar to a vacuum cleaner is disposed inside the porous roll 360 to generate a pressure difference between the first side and the second side of the porous substrate 310 to absorb the solvent. Remove

Porous substrates that can be used in the present invention are not particularly limited in kind, but are multi-layer films made by polyethylene films, polypropylene films, or combinations of these films, and polyvinylidene fluoride, polyethylene Oxide, polyacrylonitrile, or the polymer film of polyvinylidene fluoride hexafluoropropylene copolymer etc. can be used.

The slurry of the present invention may be used a mixture containing inorganic particles, a binder polymer and a solvent. Such a slurry may be used to form a coating layer on a planar substrate, which is a porous substrate, to prepare a separator having improved heat resistance having an organic-inorganic porous coating layer.

In such a separator, the inorganic particles to be used are not particularly limited as long as they are electrochemically stable. That is, the inorganic particles that can be used in the present invention are not particularly limited as long as the oxidation and / or reduction reactions do not occur in the operating voltage range (for example, 0 to 5 V on the basis of Li / Li ⁺ ) of the applied electrochemical device. In particular, in the case of using the inorganic particles having the ion transport ability, it is possible to improve the performance by increasing the ion conductivity in the electrochemical device.

In addition, when inorganic particles having a high dielectric constant are used as the inorganic particles, the ionic conductivity of the electrolyte may be improved by contributing to an increase in the dissociation degree of the electrolyte salt such as lithium salt in the liquid electrolyte.

For the above reasons, the inorganic particles preferably include high dielectric constant inorganic particles having a dielectric constant of 5 or more, preferably 10 or more, inorganic particles having a lithium ion transfer ability, or a mixture thereof.

Non-limiting examples of inorganic particles having a dielectric constant greater than or equal to BaTiO ₃ , Pb (Zr _x Ti _{1 -x} ) O ₃ (PZT, where 0 <x <1), Pb _{1 - x} La _x Zr _{1 - y} Ti _y O ₃ (PLZT, where, 0 <x <1, 0 <y <1 Im), (1-x) Pb (Mg 1/3 Nb 2/3) O 3 -xPbTiO 3 (PMN-PT, where 0 < x <1), hafnia (HfO ₂ ), SrTiO ₃ , SnO ₂ , CeO ₂ , MgO, NiO, CaO, ZnO, ZrO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , SiC, TiO ₂ Etc. can be used individually or in mixture of 2 or more types, respectively.

In particular, BaTiO ₃ , Pb (Zr _x Ti _{1- x} ) O ₃ (PZT, where 0 <x <1), Pb _{1 - x} La _x Zr _{1 -y} Ti _y O ₃ (PLZT, where 0 < x <1, 0 <y < 1 Im), (1-x) Pb (Mg 1/3 Nb 2/3) O 3 -xPbTiO 3 (PMN-PT, where 0 <x <1), hafnia (HfO Inorganic particles such as ₂ ) not only exhibit high dielectric constant characteristics of dielectric constant above 100, but also have piezoelectricity in which electric charges are generated when a tension or tension is applied under a constant pressure, thereby causing a potential difference between both surfaces. The internal short circuit of the positive electrode can be prevented from occurring, and the safety of the electrochemical device can be improved. In addition, synergistic effects of the high dielectric constant inorganic particles and the inorganic particles having lithium ion transfer ability may be doubled.

The inorganic particles having a lithium ion transfer capacity refers to inorganic particles containing lithium elements but having a function of transferring lithium ions without storing lithium, and the inorganic particles having lithium ion transfer ability are present in the particle structure. Since the lithium ions can be transferred and moved due to a kind of defect, the lithium ion conductivity in the battery is improved, thereby improving battery performance. Non-limiting examples of the inorganic particles having a lithium ion transfer capacity is 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 Such as (LiAlTiP) _x O _y series glass (0 <x <4, 0 <y <13), lithium lanthanum titanate (Li _x La _y TiO ₃ , 0 <x <2, 0 <y <3), Li _{3 .25} Ge _{0 .25} P _{0 .75} S ₄ Lithium germanium thiophosphate such as Li _x Ge _y P _z S _w , 0 <x <4, 0 <y <1, 0 <z <1, 0 <w <5), Li ₃ N, etc. Ride (Li _x N _y , 0 <x <4, 0 <y <2), Li ₃ PO ₄ -Li ₂ S-SiS ₂ SiS ₂ series glass such as Li _x Si _y S _z , 0 <x <3, 0 <y <2, 0 <z <4), LiI-Li ₂ SP ₂ S ₅ There is P ₂ S ₅ based _{glass (Li x P y S z} , 0 <x <3, 0 <y <3, 0 <z <7) or a mixture thereof as such.

In addition, the binder polymer is preferably 1 to 50% by weight relative to the inorganic particles. When the amount of the binder polymer is less than 1% by weight, the inorganic particles may not be sufficiently bound to each other, and when the amount of the binder polymer exceeds 50% by weight, the porosity of the porous coating layer may be lowered and the wettability of the electrolyte may be reduced.

As the binder polymer of the present invention, the binder polymer is polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-co-trichloroethylene, polymethyl Methacrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, ethylene vinyl acetate copolymer (polyethylene-co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylflurane (cyanoethylpullulan), cyano Polyvinyl alcohol (cyanoethylpolyvinylalcohol), cyanoethyl cellulose (cyanoethylcellulose), cyanoethyl sucrose (cyanoethylsucrose), pullulan and the like (pullulan) and carboxymethyl cellulose (carboxyl methyl cellulose), but is not limited thereto.

Examples of the solvent usable in the present invention include, but are not particularly limited to, acetone, methyl ethyl ketone (MEK), toluene, ethyl acetate, butyl acetate, methanol, ethanol, isopropyl alcohol, water, Hexane, cyclohexane, dimethyl formamide (DMF), dimethyl acetamide (DMAc), N-methyl-2-pyrrolidone (NMP) and mixtures of these solvents Etc. can be used.

An embodiment of a method of manufacturing a separator using the separator manufacturing apparatus is as follows.

First, the first surface of the planar porous substrate to be supplied is coated with a slurry including a mixture of inorganic particles, a binder polymer and a solvent.

In general, the slurry for forming the porous coating layer mixes inorganic particles with a solution in which a binder polymer and a solvent are mixed, and prepares a slurry in which inorganic particles are uniformly dispersed through a stirring process such as a ball mill. The coating method of such a slurry may use a coating method that can be generally used, and is not particularly limited in kind, but may be coated on the first surface of the porous substrate using a slot coating method using a slot die.

Thereafter, a pressure difference is generated between the first side and the second side of the porous substrate to absorb and remove the solvent through the second side of the slurry-coated porous substrate.

The solvent removal means disposed on the second side generates a pressure difference between the first side and the second side of the porous substrate coated with the slurry to absorb and remove the solvent contained in the slurry. The solvent removal step may be performed several times to increase the removal rate of the solvent. Thus, the solvent of the slurry may be removed to prepare a separator having improved heat resistance having a porous coating layer on one surface thereof. Alternatively, the slurry may optionally be heated to a constant temperature to further increase the removal efficiency of the solvent.

Alternatively, in the step of selectively removing the solvent, a solvent removal fluid may be supplied to pass through the porous substrate in the first surface to increase the solvent removal efficiency. As the solvent removal fluid, air, nitrogen, argon, helium and carbon dioxide may be used. In addition, the solvent removal fluid may be heated to a constant temperature to further improve the efficiency of solvent removal.

The separator of the present invention prepared as described above may be used as a separator of an electrochemical device. That is, the separator of the present invention can be usefully used as the separator interposed between the positive electrode and the negative electrode. Electrochemical devices include all devices that undergo an electrochemical reaction, and specific examples include capacitors such as all kinds of primary, secondary cells, fuel cells, solar cells, or supercapacitor elements. Particularly, a lithium secondary battery including a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery is preferable.

The electrochemical device may be manufactured according to conventional methods known in the art, and for example, may be manufactured by injecting an electrolyte after assembling the separator described above between an anode and a cathode. .

The electrode to be used together with the separator of the present invention is not particularly limited, and the electrode active material may be bound to an electrode current collector according to a conventional method known in the art. Non-limiting examples of the positive electrode active material of the electrode active material may be a conventional positive electrode active material that can be used for the positive electrode of the conventional electrochemical device, in particular lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium iron oxide or combinations thereof It is preferable to use one lithium composite oxide. Non-limiting examples of the negative electrode active material may be a conventional negative electrode active material that can be used for the negative electrode of the conventional electrochemical device, in particular lithium metal or lithium alloys, carbon, petroleum coke, activated carbon, Lithium adsorbents such as graphite or other carbons are preferred. Non-limiting examples of the positive electrode current collector is a foil made by aluminum, nickel or a combination thereof, and non-limiting examples of the negative electrode current collector by copper, gold, nickel or copper alloy or a combination thereof Foils produced.

Electrolyte that may be used in the present invention is A ⁺ B ^- A salt of the structure, such as, A ⁺ is Li ^+, Na ^+, K ⁺ comprises an alkaline metal cation or an ion composed of a combination thereof, such as, and 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 ) Salts containing ions consisting of anions such as ₃ ^- or combinations thereof include propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC) , Dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethylmethylcarbonate (EMC), gamma butyrolactone or mixtures thereof Some are dissolved or dissociated in an organic solvent, but are not limited thereto.

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

The separator of the present invention may be interposed between the positive electrode and the negative electrode of the secondary battery, and may be interposed between adjacent cells or electrodes when a plurality of cells or electrodes are assembled to form an electrode assembly. The electrode assembly may have various structures such as a simple stack type, a jelly roll, a stack type, and the like.

According to one embodiment, the electrode assembly may be prepared by interposing the separator of the present invention between the positive electrode and the negative electrode to which the active material is applied, and winding the positive electrode / separation membrane / cathode continuously. Alternatively, the electrode assembly may be manufactured to have a zig-zag overlapping structure by bending the anode / separator / cathode at regular intervals. Meanwhile, the electrode assembly to be wound or bent may include a plurality of electrodes and a separator that are alternately stacked to increase capacity.

According to another embodiment, the electrode assembly may be prepared by stacking the anode / separator / cathode or the cathode / separator / anode in a repeating unit. Here, the separator uses the separator of the present invention.

According to one embodiment, a plurality of unit cells having a structure of a full cell or a bicell may be prepared by gathering a folding film. Here, the folding film may use a general insulating film or the separator of the present invention. The full cell structure includes at least one cell structure having a separator interposed between electrodes having different polarities, but a cell structure having different polarities of electrodes located at the outermost sides. Examples of the full cell structure include an anode / separator / cathode or an anode / separator / cathode / separator / anode / separator / cathode. The bicell structure refers to a cell structure including at least one cell structure having a separator interposed between electrodes having different polarities, but having the same polarity as the electrode located at the outermost side. Examples of the bicell structure include an anode / separator / cathode / separator / anode or a cathode / separator / anode / separator / cathode.

There are many ways to assemble unit cells using a folding film. For example, an electrode assembly may be manufactured by arranging a plurality of unit cells on one surface of the folding film extending in a longitudinal direction at predetermined intervals and winding the folding film in one direction together with the arranged unit cells. The electrode assembly thus manufactured has a structure in which unit cells are inserted between the wound folding films. As another example, an electrode assembly may be manufactured by arranging a plurality of unit cells on both sides of the folding film extending in a longitudinal direction at predetermined intervals and winding the folding film in one direction together with the arranged unit cells. The electrode assembly thus manufactured has a structure in which unit cells are inserted between the wound folding films. The arrangement interval of the unit cells and the polarity of the electrode positioned at the outermost portion of each unit cell are selected such that the polarities of the electrodes of the upper cell and the electrodes of the lower cell in contact with the folding film are reversed. For example, an electrode disposed at an outermost interval of each unit cell and an arrangement interval of the unit cells so as to form an electrode assembly structure such as an anode / separator / cathode / folding film / anode / separator / cathode / folding film / anode. The polarity of can be selected.

In another example, a plurality of unit cells are arranged on one surface of the folding film extending in a longitudinal direction at predetermined intervals, and the folding film is bent in a zigzag shape with the arranged unit cells, and the folded film is interposed therebetween. The electrode assembly may be manufactured in a structure in which the unit cells are arranged. The electrode assembly manufactured as described above has a structure in which unit cells are inserted between folded and stacked folding films. As another example, after arranging a plurality of unit cells on both sides of the folding film extending in a longitudinal direction at predetermined intervals, the folding film is bent in a zigzag shape with the arranged unit cells, and unit cells are formed between the folded folding films. The electrode assembly may be manufactured with the disposed structure. The electrode assembly manufactured as described above has a structure in which unit cells are inserted between folded and stacked folding films. The arrangement interval of the unit cells and the polarity of the electrode positioned at the outermost portion of each unit cell are selected such that the polarities of the electrodes of the upper cell and the electrodes of the lower cell in contact with the folding film are reversed. For example, an electrode disposed at an outermost interval of each unit cell and an arrangement interval of the unit cells so as to form an electrode assembly structure such as an anode / separator / cathode / folding film / anode / separator / cathode / folding film / anode. The polarity of can be selected.

In addition, a method of collecting electrodes using a folding film may be various. For example, an electrode assembly may be manufactured by alternately arranging a cathode, an anode, a cathode, an anode, etc. on one surface of the folding film, and winding an electrode disposed together with the folding film in one direction. The electrode assembly thus manufactured has a structure in which electrodes are inserted between the wound folding films. As another example, the electrode assembly may be manufactured by arranging a plurality of electrodes on both sides of the folding film extending in the longitudinal direction at predetermined intervals and winding the folding film in one direction together with the arranged electrodes. The electrode assembly thus manufactured has a structure in which electrodes are inserted between the wound folding films. The spacing of the electrodes and the polarity of the electrodes are selected such that the polarities of the upper and lower electrodes in contact with the folding film are reversed. For example, the arrangement interval of the electrodes and the polarity of each electrode may be selected to form the structure of the electrode assembly such as the anode / folding film / cathode / folding film / anode.

In another example, an electrode, an anode, a cathode, an anode, etc. are alternately arranged on one side of the folding film, the electrodes arranged together with the folding film in one direction are bent, and the electrodes are disposed between the folded folding films. The electrode assembly can be manufactured with the structure. The electrode assembly thus manufactured has a structure in which the electrodes are inserted between the folded and stacked folding films. As another example, after arranging a plurality of electrodes on both sides of the folding film extending in the longitudinal direction at predetermined intervals, the folding film is bent together with the arranged electrodes, so that the unit cells are arranged between the bent folding films. The assembly can be manufactured. The electrode assembly thus manufactured has a structure in which the electrodes are inserted between the folded and stacked folding films. The spacing of the electrodes and the polarity of the electrodes are selected such that the polarities of the upper and lower electrodes in contact with the folding film are reversed. For example, the arrangement interval of the electrodes and the polarity of each electrode may be selected to form the structure of the electrode assembly such as the anode / folding film / cathode / folding film / anode.

On the other hand, the length of the folding film used to manufacture the electrode assembly may be selected to wrap the last unit cell or electrode in the manner described above, and then wrap the electrode assembly at least once. However, the electrode assemblies may be modified in various other forms, and the scope of the present invention is not limited thereto.

Hereinafter, the present invention will be described in detail with reference to Examples. However, the embodiments according to the present invention can be modified into various other forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

Example

Example  1.With porous coating layer using acetone solvent Separator  Produce

500 nm diameter in a binder polymer solution in which polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP) and cyanoethylpullulan were mixed at a weight ratio of 10: 2 and dissolved to have a concentration of 5% by weight. After adding the alumina (Al ₂ O ₃ ) particles having a weight ratio of binder polymer / inorganic particles = 10/90, the slurry was prepared by dispersing by a ball mill method. The prepared slurry was applied on a polyolefin separation membrane (SK energy, 512 GK) having a thickness of 12 μm by a slot coating method, and a solvent was removed under normal temperature conditions using a suction belt to complete drying. The average thickness of the porous coating layer of the separator thus formed was 3.1 μm, and the aeration time was good as 227 sec / 100 cc.

Example  2. NMP  With a porous coating layer using a solvent Separator  Produce

Coating and drying were carried out in the same manner as in Example 1 except that the solvent was replaced with acetone and NMP in preparing the slurry. The thickness of the porous coating layer of the separator thus formed was 3.0 ㎛, the aeration time was good as 230sec / 100cc.

Comparative example  1. Use acetone solvent Heat-dry  With porous coating layer Separator  Produce

500 nm diameter in a binder polymer solution in which polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP) and cyanoethylpullulan were mixed at a weight ratio of 10: 2 and dissolved to have a concentration of 5% by weight. After adding the alumina (Al ₂ O ₃ ) particles having a weight ratio of binder polymer / inorganic particles = 10/90, the slurry was prepared by dispersing by a ball mill method. The prepared slurry was applied on a 12 μm thick polyolefin membrane (SK energy, 512 GK) by a slot coating method.

Drying was completed by passing the slurry-coated polyolefin membrane through an oven maintained at 80 ° C. The average thickness of the porous coating layer in the center of the separator thus formed was 3.3 μm, and the aeration time was good as 235 sec / 100 cc, but curl was generated at both ends of the separator, resulting in poor production yield.

Comparative example  2. NMP  Using solvent Heat-dry  With porous coating layer Separator  Produce

A slurry was prepared in the same manner as in Comparative Example 1 except that the solvent was replaced with NMP in acetone. The prepared slurry was applied on a 12 μm thick polyolefin membrane (SK energy, 512 GK) by a slot coating method.

The slurry-coated polyolefin membrane was passed through an oven maintained at 80 ° C. However, curls occurred at both ends of the polyolefin membrane, and the drying of the solvent was not completed, so that a porous coating layer could not be formed.

100,200,300: separator manufacturing apparatus 110,210,310: porous substrate
120,220,320: Porous substrate supply means 130,230,330: Slot die
140,240: porous endless belt 150,250,370: solvent suction
260: solvent removing fluid supply means 360: porous roll
380 guide roll

Claims (18)

Porous substrate supply means for supplying a planar porous substrate;
Coating means disposed on a first side of the porous substrate to be supplied, and coating the first side of the porous substrate with a slurry including a mixture of inorganic particles, a binder polymer, and a solvent;
And a solvent removing means disposed on the second surface of the porous substrate and removing the solvent from the slurry-coated porous substrate by using the pressure difference between the first surface and the second surface. The method of claim 1,
The separator manufacturing apparatus may further include a solvent removing fluid supply means disposed on a first surface of the porous substrate facing the solvent removing means and supplying a solvent removing fluid to pass through the porous substrate coated with a slurry. Separator manufacturing apparatus characterized by the above-mentioned. The method of claim 2,
The solvent removing fluid is an apparatus for producing a separator, characterized in that one or a mixture of two or more fluids selected from air, nitrogen, argon, helium and carbon dioxide. The method of claim 1,
The coating means is a separator manufacturing apparatus characterized in that it comprises a slot die. The method of claim 1,
The solvent removing means comprises a porous endless belt traveling in contact with the second surface of the porous substrate; A driving unit for driving the porous endless belt; And a suction part positioned inside the porous endless belt and absorbing and removing the solvent by generating a pressure difference between the first surface and the second surface. The method of claim 1,
Wherein the solvent removal means comprises a hollow cylindrical porous roll driven in contact with the second surface of the porous substrate; A guide roll disposed to face the porous roll and being in contact with the first surface; And a suction part positioned inside the porous roll to absorb and remove the solvent by generating a pressure difference between the first surface and the second surface. The method of claim 1,
The porous substrate may be a polyethylene film, a polypropylene film, or a multilayer film prepared by a combination of these films, and polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, or polyvinylidene fluoride including micropores. A device for producing a separator, wherein the separator is a polymer film of a hexafluoropropylene copolymer. The method of claim 1,
The inorganic particles are inorganic particles having a dielectric constant of 5 or more, inorganic particles having a lithium ion transfer capacity, and an inorganic particle selected from the group consisting of a mixture thereof. 9. The method of claim 8,
The inorganic particles having a dielectric constant of 5 or more include 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 hafnia, 0 <x <1, 0 <y <1), (1-x) Pb (Mg 1/3 Nb 2/3) O 3 -xPbTiO 3 (PMN-PT, 0 <x <1), ( 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 An apparatus for producing a separator, characterized in that the particles or a mixture of two or more thereof. 9. The method of claim 8,
The inorganic particles having a lithium ion transfer ability include lithium phosphate (Li ₃ PO ₄ ), lithium titanium phosphate (Li _x Ti _y (PO ₄ ) ₃ , 0 <x <2, 0 <y <3), and 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 series glass (0 <x <4, 0 <y <13), lithium lanthanum titanate (Li _x La _y TiO ₃ , 0 <x <2, 0 <y <3), lithium germanium thiophosphate (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), SiS ₂ (Li _x Si _y S _z , 0 <x <3, 0 <y <2, 0 <z <4) Series glass and P ₂ S ₅ (Li _x P _y S _z , 0 <x <3, 0 <y <3, 0 <z <7) any one inorganic particle selected from the group consisting of series glass or a mixture of two or more thereof. The method of claim 1,
The weight ratio of the inorganic particles and the binder polymer is 50:50 to 99: 1, the manufacturing apparatus of the separator. The method of claim 1,
The binder polymer may be polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-co-trichloroethylene, polymethylmethacrylate, Polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, ethylene vinyl acetate copolymer, polyethylene oxide oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, cyanoethyl Polyvinyl alcohol (cyanoethylpolyviny) lalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, and carboxyl methyl cellulose, any one binder polymer selected from the group consisting of two or more thereof An apparatus for producing a separator, characterized in that the mixture. The method of claim 1,
The solvent is acetone, methyl ethyl ketone (MEK), toluene, ethyl acetate, butyl acetate, methanol, ethanol, isopropyl alcohol, water, hexane, cyclohexane, dimethyl formamide (dimethyl formamide, DMF), Apparatus for producing a separator, characterized in that one solvent or a mixture of two or more selected from dimethyl acetamide (DMAc) and N-methyl-2-pyrrolidone (NMP) . Coating the first surface of the planar porous substrate to be supplied with a slurry comprising a mixture of inorganic particles, a binder polymer and a solvent; And
Generating a pressure difference between the first side and the second side of the porous substrate, thereby absorbing and removing the solvent through the second side of the porous substrate coated with the slurry. 15. The method of claim 14,
In the method of manufacturing the separator, in the step of removing the solvent, a method of manufacturing a separator, characterized in that to supply a solvent removal fluid to pass through the porous substrate on the first side. 16. The method of claim 15,
The solvent removing fluid is a method for producing a separator, characterized in that the fluid or a mixture of two or more selected from air, nitrogen, argon, helium and carbon dioxide. In the electrochemical device comprising a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode,
The separator is an electrochemical device, characterized in that the separator manufactured by any one of claims 14 to 16. 18. The method of claim 17,
The electrochemical device is an electrochemical device, characterized in that the lithium secondary battery.

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