KR20170087136A - Method of Manufacturing Separator for Electrochemical Devices - Google Patents

Abstract

The present invention relates to a method for producing a separator for an electrochemical device,
(i) forming a coating layer by applying a coating agent to one or both surfaces of a porous membrane substrate;
(ii) cutting both side end portions of the coating layer so that the thickness of the coating layer at both side end portions is relatively smaller than the thickness of the coating layer at the center portion in the width direction of the separator base material; And
(iii) a step of moving the separator base material having both side end portions of the coating layer cut into a dryer and drying to form a coated portion;
The present invention also provides a method for producing a separation membrane.

Description

TECHNICAL FIELD [0001] The present invention relates to a separator for electrochemical devices,

The present invention relates to a process for producing a separator for electrochemical devices.

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.

Typically, in terms of the shape of a battery, there is a high demand for a prismatic secondary battery and a pouch-type secondary battery which can be applied to products such as mobile phones with a small thickness, and has advantages such as high energy density, discharge voltage, There is a high demand for lithium secondary batteries such as lithium ion batteries and lithium ion polymer batteries.

Also, the secondary battery is classified according to how the electrode assembly having the anode / separator / cathode structure is formed. Typically, the long battery-shaped anodes and cathodes are jelly- A stacked (stacked) electrode assembly in which a plurality of positive electrodes and negative electrodes cut in units of a predetermined size are sequentially stacked with a separator interposed therebetween, a stacked (stacked) electrode assembly in which a predetermined unit of positive and negative electrodes are stacked, A stack / folding type electrode assembly having a structure in which a bi-cell or a full cell stacked in a single state is wound around a separator sheet.

The lithium secondary battery uses a metal oxide such as LiCoO ₂ as a positive electrode active material and a carbon material as a negative electrode active material and a nonaqueous electrolytic solution containing a lithium salt such as LiPF ₆ is inserted between the negative electrode and the positive electrode through a polyolefin- . During charging, lithium ions of the positive electrode active material are released and inserted into the carbon layer of the negative electrode. In discharging, lithium ions of the negative electrode carbon layer are discharged and inserted into the positive electrode active material. In this case, As a medium for transporting the liquid. In such a lithium secondary battery, charging and discharging proceed while repeating the process of intercalating and deintercalating lithium ions in the anode.

Basically, an electrode assembly composed of a positive electrode / separator / negative electrode may have a laminated structure, but a structure in which a plurality of electrodes (positive electrode and negative electrode) are laminated in a state in which a separator is interposed and then bonded to each other by heating / ≪ / RTI > In this case, the bonding of the electrode and the separator is achieved by heating / pressing the electrode and the adhesive layer formed on the separator in a face-to-face relationship.

In recent years, in order to solve the thermal and mechanical safety problems in the production of such a separator, an organic / inorganic composite separator in which a slurry containing inorganic particles and a binder polymer is coated on a separator substrate has been proposed.

The coating of the coating layer on the surface of the separator is generally performed by using a roller using a roller in addition to dip coating in which a separator sheet is immersed in a mixed solution in which a binder and an inorganic component are dispersed to form a coating layer roll coating method or the like.

However, when the separator substrate coated by the coating method is dried, relatively fast drying is performed at both side ends in the width direction of the separator substrate, so that the thickness of the coating layer at both ends is relatively increased , Which is referred to as a high edge phenomenon). The high edge phenomenon will be described in more detail below with reference to Fig. 1 which shows a cross-section of the coated membrane base in the width direction.

Referring to FIG. 1, when the separation layer 100 coated on both sides of the separation membrane substrate 110 is dried, relatively fast drying occurs at the both ends A of the separation membrane substrate 110 , The solvent at the central portion of the separator base 110 moves to both side ends A. At this time, the slurry in the central portion is also moved to the both side ends A by the movement of the solvent, and the thickness of the both side ends A is relatively increased compared to the central portion after drying. Such a phenomenon is a serious problem in manufacturing an electrode assembly including the separator, such as lowering the quality of the product and causing a risk of short circuit

Therefore, there is a high need for a method for producing a separation membrane that can solve such a problem.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and the technical problems required from the past.

Specifically, it is an object of the present invention to provide a method of manufacturing a membrane-electrode assembly, which comprises the steps of cutting both side end portions of a coating layer so that the thickness of a coating layer at both side end portions is relatively smaller than a thickness of a coating layer at a center portion, In which the thickness of the coated portion is the same at the end portion and the central portion, thereby achieving a desired effect.

According to an aspect of the present invention, there is provided a method of manufacturing a separation membrane for an electrochemical device,

 (i) forming a coating layer by applying a coating agent to one or both surfaces of a porous membrane substrate;

(ii) cutting both side end portions of the coating layer so that the thickness of the coating layer at both side end portions is relatively smaller than the thickness of the coating layer at the center portion in the width direction of the separator base material; And

(iii) a step of moving the separator base material having both side end portions of the coating layer cut into the dryer and drying to form a coated portion;

As shown in FIG.

As described above, according to the manufacturing method of the present invention, even if the thickness of both end portions of the coating layer is increased due to the high edge phenomenon in the drying process by cutting both side end portions of the coating layer before moving the coated separator substrate into the dryer, The thickness of the coating portion in the separation membrane after drying may be the same at the both end portions and the center portion.

The method of forming the coating layer in the step (i) is not particularly limited, but specific examples thereof include a dip coating method, a forward roll coating method, a reverse roll coating method, a microgravure a microgravure coating method, and a direct metering coating method, or may be formed by a combination of two or more methods.

The coating layer of the process (i) may be formed, for example, such that the thickness of the coating layer at both side end portions in the width direction of the separator base material is the same as the thickness of the coating layer at the center portion, It may be formed to have a somewhat thin thickness.

The separation membrane substrate formed with the coating layer in the process (i) moves to the process (ii) for cutting the coating layer, and the size of both end portions cut in the process (ii) depends on the composition of the coating material affecting the high edge phenomenon, Temperature, and drying time. In detail, it may be formed in a range of 2% to 20% on the basis of the width of the separator base material in a plan view. If the size of the cut end portions is less than 2%, it is impossible to cancel out the height increase of both end portions due to the high edge phenomenon, and if it is 20% or more, The height of the center portion can be less than the height of the center portion.

In one specific example, the both side end portions cut in the process (ii) may have a tapered structure in which the thickness of the coating layer decreases from the center to the end of the membrane base material on the vertical cross section. The shape in which the thickness of the coating layer is reduced is not limited to the tapered structure but may be variously determined in consideration of the drying temperature, the drying time, and the composition of the coating agent. Specific examples thereof include a straight line, an outwardly convex curve, Convex curves, and combinations of these shapes.

In particular, the minimum coating layer thickness at the cut end portions of the separator film at the both end portions may be in a range of 10% to 60% of the thickness of the coating layer at the center portion of the separator base. If the minimum coating layer thickness at the end of the membrane substrate is less than 10% of the thickness of the coating layer at the central portion of the separator substrate, it is not possible to offset the height increase at both ends due to the high edge phenomenon, The height of both ends of the separator after drying may be less than the height of the central portion, which is not preferable.

In addition, in the step (ii), both side end portions may be cut so that the average thickness of the coating layer is 30% to 80% of the thickness of the coating layer in the central portion. When the average thickness of the coating layer at both side end portions is less than 30% with respect to the thickness of the coating layer at the center portion outside the above range, the height increase of the both side ends due to the high edge phenomenon can not be canceled, The height of both ends of the separator after drying may be less than the height of the central portion, which is not preferable. More preferably, the average thickness of the coating layer at both end portions is 40% to 70% of the thickness of the coating layer at the central portion.

In the step (ii), the method of cutting the coating layer is not particularly limited, but as one concrete example, a meyer bar can be used for cutting the coating layer. At this time, the cutting residue transferred directly to the Meyer by the cutting of the coating layer may be removed by a doctor blade as one specific example. That is, the doctor blade comes into contact with the surface of the rotating Meyer bar, thereby removing the cutting residue from the bar.

As another example, the cutting remainder may be removed by a cleaning roller rotating in the opposite direction in close contact with the Meyer bar. At this time, the cleaning roller is immersed in a cleaning bath containing a solvent so that the cutting residue can be continuously removed from the cleaning roller. If the cutting residue can be prevented from adhering to the cleaning roller, the kind of the solvent is not particularly limited, and for example, NMP used in the electrode slurry may be used.

The coating removed by the method described above can be accommodated in a cleaning bath.

The porous separator base material is not limited as long as it has a structure having pores. Specifically, the porous separator base material may be made of a polyolefin-based polymer, and examples thereof include high density polyethylene, linear low density polyethylene, low density polyethylene, ultra high molecular weight polyethylene, And derivatives thereof. Typical commercially available examples of the substrate include a wet polyethylene type (Asahi-Kasei E-Materials, Toray, SK Innovation, Entek), a dry polypropylene type (Shenzhen Senior), a dry polypropylene / polyethylene multilayered structure (Polypore, Ube) May be used, but is not limited thereto.

The thickness of such a polyolefin-based membrane base material is not particularly limited, but is preferably in the range of 1 to 100 mu m, more preferably in the range of 5 to 50 mu m. If it is less than 1 탆, it is difficult to maintain the mechanical properties, and when it exceeds 100 탆, it can act as a resistive layer.

The pore size and porosity in the polyolefin-based membrane substrate are not particularly limited, but the pore size is preferably in the range of 10 to 95% and the pore size (diameter) is preferably in the range of 0.1 to 50 μm. When the pore size and the porosity are less than 0.1 μm and less than 10%, respectively, they act as resistance layers. If the pore size and porosity are more than 50 μm and 95%, it becomes difficult to maintain the mechanical properties. In addition, the polyolefin-based membrane substrate may be in the form of fibers or membranes.

The coating agent applied to the separator substrate comprises inorganic particles and a binder polymer.

The inorganic particles serve as a kind of spacer which can form voids between inorganic particles to form micropores and maintain a physical shape. In general, even when the temperature is 200 ° C or higher, physical properties Since it has unchanged characteristics, it provides excellent heat resistance to the separator.

The inorganic particles usable in the present invention can be oxidized in an operating voltage range of the applied electrochemical device (for example, 0 to 5 V based on Li / Li +), And / or a reduction reaction does not occur. Particularly, when inorganic particles having an ion-transporting ability are used, the ion conductivity in the electrochemical device can be increased and the performance can be improved. Therefore, it is preferable that the ionic conductivity is as high as possible. In addition, when the inorganic particles have a high density, it is difficult to disperse the particles at the time of coating, and there is a problem of an increase in weight in the production of an electrochemical device. In the case of an inorganic substance having a high dielectric constant, dissociation of an electrolyte salt, for example, a lithium salt, in the liquid electrolyte also contributes to increase ionic conductivity of the electrolyte.

For the reasons stated above, the inorganic particles may be selected from the group consisting of high-permittivity inorganic particles having a dielectric constant of 5 or more, preferably 10 or more, inorganic particles having piezoelectricity, inorganic particles having lithium ion transferring ability, .

Examples of the inorganic particles having a dielectric constant of 5 or more include SrTiO ₃ , SnO ₂ , CeO ₂ , MgO, NiO, CaO, ZnO, ZrO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , TiO ₂ , SiC, However, the present invention is not limited thereto.

The piezoelectricity inorganic particle means a non-conductive material at normal pressure or a material having electrical conductivity due to a change in internal structure when a certain pressure is applied, and exhibits a high permittivity with a dielectric constant of 100 or more, The charge is generated in the case of applying tensile or compressive force, so that one side is charged positively and the other side is negatively charged, thereby generating a potential difference between both sides.

In the case of using inorganic particles having the above characteristics, when an internal short-circuit of both electrodes occurs due to an external impact such as local crush or nail, the anode and the cathode are in direct contact with each other due to the inorganic particles coated on the separator In addition, due to the piezoelectricity of the inorganic particles, a potential difference is generated in the particle. As a result, the electron transfer between the two electrodes, that is, the flow of a minute current, is performed, thereby reducing the voltage of the electrochemical device and improving safety .

Examples of the inorganic particles having piezoelectricity include 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 ), or mixtures thereof.

The inorganic particles having the lithium ion transferring ability refer to inorganic particles that contain a lithium element but do not store lithium but have a function of transferring lithium ions. The inorganic particles having lithium ion transferring ability exist in the particle structure Since lithium ions can be transferred and transferred due to a kind of defect, the lithium ion conductivity in the electrochemical device can be improved and the performance of the electrochemical device can be improved.

Examples of the inorganic particles having lithium ion transferring ability include lithium phosphate (Li ₃ PO ₄ ), lithium titanium phosphate (Li _x Ti _y (PO ₄ ) ₃ , 0 <x <2, 0 <y < (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 (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 (Li _x Ge _y P _z S _w , 0 <x <4, 0 <y <1, 0 <z <1, 0 <w <5) such as _0.25 P _0.75S4 , Li ₃ N lithium nitride such as _{(Li x N y, 0 <} x <4, 0 <y <2), Li 3 PO 4 -Li 2 S-SiS 2 SiS 2 family, such as glass (Li _x Si _y S _z, 0 <x <3, 0 <y <2, 0 <z <4), LiI-Li 2 SP 2 S 5 P 2 S 5 based _{glass (Li x P y S z} , 0 <x <3, such as 0 < y < 3, 0 < z < 7), or a mixture thereof.

When the above-mentioned high-permittivity inorganic particles, piezoelectric particles, and inorganic particles having lithium ion-transporting ability are mixed, their synergistic effect can be doubled.

The size of the inorganic particles is not limited, but is preferably in the range of 0.001 to 10 mu m for the formation of a film of uniform thickness and a suitable porosity. When the thickness is less than 0.001 탆, the dispersibility of the separator is deteriorated and it is difficult to control the physical properties of the separator. When the thickness exceeds 10 탆, the thickness of the separator formed with the same solid content is increased to decrease the mechanical properties. The probability of an internal short circuit occurring during charging and discharging of the chemical device increases.

The content of the inorganic particles is not particularly limited, but is preferably 50 to 99% by weight, more preferably 60 to 95% by weight based on 100% by weight based on the total weight of the coating layer. When the amount is less than 50% by weight, the content of the polymer is excessively increased, and the pore size and the porosity due to the reduction of the void space formed between the inorganic particles may be decreased, resulting in a deterioration of the performance of the final electrochemical device. On the other hand, if it exceeds 99% by weight, the mechanical properties of the final separator are deteriorated due to the weak adhesive force between the inorganic materials because the polymer content is too small.

As another constituent of the coating layers, the binder polymer may be a material having a glass transition temperature (Tg) as low as possible, and preferably in the range of -200 to 200 ° C.

In addition, the binder polymer may have a characteristic of being capable of exhibiting a high degree of swelling of the electrolyte when being gelled upon impregnation with a liquid electrolyte. In fact, when the binder polymer is a polymer having an excellent electrolyte impregnation rate, the electrolyte injected after the electrochemical device is impregnated with the polymer, and the polymer having the absorbed electrolyte has electrolytic ion conduction capability. In addition, wetting of an electrolytic solution for an electrochemical device is improved as compared with the conventional hydrophobic polyolefin-based separator, and a polar electrolyte for an electrochemical device, which has been conventionally difficult to use, can be applied. Therefore, if possible, a polymer having a solubility index of 15 to 45 MPa &lt; 1/2 &gt; is preferable, and 15 to 25 MPa &lt; 1/2 &gt; and 30 to 45 MPa & When the solubility index is less than 15 MPa &lt; 1/2 &gt; and more than 45 MPa &lt; 1/2 &gt;, it is difficult to be swelled by a conventional liquid electrolyte for an electrochemical device.

Specifically, the binder polymer may be selected from the group consisting of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-trichlorethylene, polyvinylidene fluoride-chlorotrifluoroethylene, polymethyl methacrylate Polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, ethylene vinyl acetate copolymer, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, cyanoethylpolylane, And may be one or more selected from the group consisting of vinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, carboxymethyl cellulose, acrylonitrile styrene butadiene copolymer, and polyimide.

The present invention also provides an electrochemical device comprising an anode and a cathode, a separator interposed between the anode and the cathode, and an electrolyte. Here, the thickness of the membrane coating portion is the same at the end portion and the center portion. The electrochemical device may be a capacitor or a lithium secondary battery. The capacitor and the lithium secondary battery are well known in the art, and a detailed description thereof will be omitted herein.

As described above, in the method for manufacturing a separation membrane for an electrochemical device according to the present invention, both side end portions of the coating layer are cut so that the thickness of the coating layer at both side end portions is relatively smaller than the thickness of the coating layer at the center portion in the width direction of the separation membrane base material The thickness of the coating portion in the separation membrane after drying is the same at the end portion and the center portion even if the height of both end portions due to the high edge phenomenon occurs during the drying process, The quality can be improved, and the risk of short circuit and the like can be remarkably reduced.

1 is a schematic view of a separation membrane showing a high edge phenomenon occurring in the drying process of the prior art;
2 is a schematic view illustrating a process of manufacturing a separation membrane according to an embodiment of the present invention;
Fig. 3 is a schematic view showing a separator substrate in which both side end portions of the coating layer are cut in the process (ii) of Fig. 2;
FIG. 4 is an enlarged schematic view showing a vertical section of a meyer bar used for cutting a coating layer in the process (ii) of FIG. 2; FIG.
FIG. 5 is a schematic view showing that the cutting residue transferred directly to Meyer in FIG. 4 is removed using a cleaning roller instead of a doctor blade.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited by the scope of the present invention.

2 is a schematic view illustrating a process of manufacturing a separation membrane according to an embodiment of the present invention.

Referring to FIG. 2, the separator manufacturing method includes the steps of (i) applying a coating agent to both surfaces of the porous separator substrate 210 to form a coating layer, (ii) (Iii) cutting the separator base material 210 having both sides of the coating layer cut into the dryer 600 and drying the same at the both ends of the coating layer so that the thickness thereof is relatively smaller than the thickness of the coating layer at the center portion; And forming a coating portion.

In step (i), the coating layer is formed by a dip coating method. As shown in Fig. 1, the thickness of the coating layer at both side end portions in the width direction of the separation membrane base material is formed to be equal to the thickness of the coating layer at the central portion.

FIG. 3 is a schematic view showing a separation membrane substrate in which both end portions of the coating layer are cut in the process (ii) of FIG. 2;

Referring to FIG. 3, the size L of both end portions cut in the process (ii) is 2% to 20% on the basis of the width W of the separator base 210 on a plane. In addition, the cut end portions have a structure in which the thickness of the coating layer 220 decreases from the center to the end of the separator base 210 on the vertical cross section.

The thickness h of the minimum coating layer 220 at the cut end portions of the separator base 210 is in a range of 10% to 60% of the thickness H of the coating layer 220 at the center portion of the separator base 210, The average thickness of the coating layer 220 at the end portion is cut to be 40% to 70% with respect to the thickness H of the coating layer 220 at the center portion.

FIG. 4 is an enlarged schematic view showing a vertical section of the Meyer bar 400 used for cutting the coating layer in the process (ii) of FIG.

Referring to FIG. 4, the coating layer formed in the process (i) of FIG. 2 is cut by the Meyer bar 400 in the process (ii) of FIG. At this time, the cutting residue transferred to the Meyer bar 400 by cutting of the coating layer is removed by a doctor blade 410. The coating material thus removed is accommodated in a cleaning bath 420.

FIG. 5 is a schematic view showing a process of removing the cutting residue transferred to Meyer in FIG. 4 by using a cleaning roller instead of the doctor blade 410.

Referring to FIG. 5, the cutting remainder transferred to the mower bar 400 by the cutting of the coating layer in FIG. 4 is removed by the cleaning roller 430 rotating in the opposite direction in close contact with the Meyer bar 400 Removed. The cleaning roller 430 is immersed in a cleaning bath 440 containing a solvent in a portion facing the Meyer bar 400 and the removed coating agent is accommodated in the cleaning bath 440.

In the above-described process (ii), when the separation membrane base material having both side end portions of the coating layer cut into the dryer is dried to form the coating portion, the thickness of the coating portion is uniformly formed at the end portion and the center portion.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention.

Claims (20)

A method of producing a separator for an electrochemical device,
(i) forming a coating layer by applying a coating agent to one or both surfaces of a porous membrane substrate;
(ii) cutting both side end portions of the coating layer so that the thickness of the coating layer at both side end portions is relatively smaller than the thickness of the coating layer at the center portion in the width direction of the separator base material; And
(iii) a step of moving the separator base material having both side end portions of the coating layer cut into a dryer and drying to form a coated portion;
&Lt; / RTI &gt; The method according to claim 1, wherein the coating layer in the step (i) is selected from the group consisting of a dip coating method, a forward roll coating method, a reverse roll coating method, a microgravure coating method, A direct metering coating method, or a combination of two or more methods. The method for producing a separation membrane according to claim 1, wherein the coating layer of the process (i) has a thickness of a coating layer at both side end portions in a width direction of the separation membrane base material equal to a thickness of a coating layer at a central portion. [2] The method of claim 1, wherein the size of the cut end portions in the step (ii) ranges from 2% to 20% based on the width of the separator base material in a plan view. The method according to claim 1, wherein the both end portions cut in the step (ii) have a tapered structure in which the thickness of the coating layer decreases from the center to the end of the membrane base material on the vertical cross section. 6. The method of claim 5, wherein the minimum coating layer thickness at the cut end portions of the separator substrate ranges from 10% to 60% of the thickness of the coating layer at the center portion of the separator substrate. The method according to claim 1, wherein in the step (ii), both end portions are cut so that the average thickness of the coating layer is 30% to 80% of the thickness of the coating layer in the central portion. The method according to claim 1, wherein in the step (ii), both end portions are cut so that the average thickness of the coating layer is 40% to 70% of the thickness of the coating layer in the central portion. The method of claim 1, wherein in step (ii), a Meyer bar is used for cutting the coating layer. 10. The method of claim 9, wherein the cutting residue transferred directly to the mica by cutting of the coating layer is removed by a doctor blade. The manufacturing method of a separation membrane according to claim 9, wherein the cutting residue transferred directly to the mica by the cutting of the coating layer is removed by a cleaning roller rotating in the opposite direction in close contact with the mire bar Way. The separation membrane manufacturing method according to claim 11, wherein the cleaning roller is immersed in a cleaning bath in which a portion facing the Meyer bar is filled with a solvent. The method of claim 1, wherein the porous separator substrate comprises a polyolefin-based polymer resin. The method of claim 1, wherein the coating agent comprises inorganic particles and a binder polymer. 15. The method of claim 14, wherein the binder polymer is selected from the group consisting of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-trichlorethylene, polyvinylidene fluoride-chlorotrifluoroethylene, Polyvinyl pyrrolidone, polyvinyl acetate, ethylene vinyl acetate copolymer, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, polyvinyl pyrrolidone, Is one or two or more selected from the group consisting of cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, carboxymethyl cellulose, acrylonitrile styrene butadiene copolymer, and polyimide (2). 15. The method according to claim 14, wherein the inorganic particles are at least one selected from the group consisting of high-permittivity inorganic particles having a dielectric constant of 5 or more, inorganic particles having piezoelectricity, inorganic particles having lithium ion transporting ability, By weight based on the total weight of the separator. A separator for an electrochemical device, which is produced by the method according to any one of claims 1 to 16. The separator for an electrochemical device according to claim 17, wherein the thickness of the coating portion in the separator is the same at the end portion and the central portion. An electrochemical device comprising an anode and a cathode, a separator according to claim 18 interposed between the anode and the cathode, and an electrolyte. The electrochemical device according to claim 19, wherein the electrochemical device is a lithium secondary battery.

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