KR20190025462A - A separator for electrochemical device and a method for manufacturing the the same - Google Patents

Abstract

The present invention relates to a separator, which is excellent in electrolyte wettability and electrode binding properties and does not need to have a separate electrode adhesive layer for increasing binding power with an electrode, and a manufacturing method for the same. According to the present invention, the separator has an effect of increasing the binding power with the electrode by a plasma treatment part by performing a plasma treatment only for a predetermined part of a surface. Also, the separator prevents excessive binding between the electrode and the separator through a plasma non-treatment part and can allow the non-treatment part to be provided to a passage, in which an electrolyte flows inside electrode assembly, so as to improve the electrolyte wettability. Moreover, the separator of the present invention does not need to have the separate adhesive layer for increasing the binding power with the electrode. Therefore, interfacial resistance between the electrode and the separator is low and a thin-type electrochemical device can be manufactured.

Description

[0001] The present invention relates to a separator for electrochemical devices and a method for manufacturing the separator.

The present invention relates to a separator for an electrochemical device and a method for producing the separator. More specifically, the present invention relates to a separator which is excellent in electrolyte wettability and electrode binding property and does not need to have a separate electrode adhesive layer to increase binding strength with an electrode, and a method of manufacturing the same.

The secondary battery is based on anode / cathode / separator / electrolytic solution, and it is widely used for small electronic equipment such as mobile phones and notebooks. In recent years, hybrid electric vehicles (HEV), plug-in EVs, electric bikes (e-bikes) and energy storage systems (Energy Storage System, ESS) is rapidly expanding.

The securing of safety in the manufacture and use of such a secondary battery is an important problem. Particularly, a separator commonly used in an electrochemical device has a problem of stability such as an internal short circuit by exhibiting extreme thermal shrinkage behavior in a high temperature condition due to its material properties and manufacturing process characteristics. In recent years, an organic-inorganic composite porous separator has been proposed in which a mixture of inorganic particles and a binder resin is coated on a porous polymer substrate for a secondary battery separator to form a porous inorganic coating layer to secure the safety of the secondary battery (Korean Patent Application No. 10-2004- 0070096). However, when the electrode assembly is formed by laminating the electrode and the separator, the interlayer adhesion is insufficient and there is a great risk that the electrode and the separator are separated from each other. In this case, the inorganic particles desorbed during the separation process may act as local defects in the device exist.

In order to solve this problem, JP-A-10-2006-0116043 discloses a method in which a porous adhesive layer is obtained by adding ethanol to a solution prepared by dissolving PVDF in a good solvent such as acetone, .

The porous adhesive layer obtained by this method has the advantages of excellent wettability and low resistance in battery operation. However, in order to apply such a technique, an excessive amount of binder is required, which is not suitable for high output design. In addition, due to the swelling after the liquid injection in the manufacturing process of the battery, the coupling strength with the separator, that is, the mechanical strength is lowered, the low cycling characteristic is exhibited, and interlayer mixing with the porous inorganic coating layer occurs, There is a problem that the air permeability of the separation membrane is lowered by closing the pores.

It is an object of the present invention to provide a separator for an electrochemical device having excellent electrode adhesiveness and wettability. It is another object of the present invention to provide a separator which is not provided with a separate adhesive layer and is capable of producing a thin-film battery. Finally, it is an object of the present invention to provide a method for producing a separation membrane having the above-mentioned characteristics. Other objects and advantages of the present invention will become apparent from the following description. On the contrary, it is to be understood that the objects and advantages of the present invention can be realized by the means or method described in the claims, and the combination thereof.

The present invention relates to a separator for an electrochemical device and a method of manufacturing the same. The first aspect of the present invention is a separation membrane for an electrochemical device, wherein the separation membrane is formed by applying at least one treatment selected from the group consisting of corona discharge, atmospheric pressure plasma, ozone treatment and ultraviolet irradiation to the surface of the outermost layer on both sides or one side, And the surface treatment portion is a checkerboard pattern formed by intersecting the stripe patterns and / or the respective stripes. The surface treatment portion has a surface area of less than 50% of 100% of the total surface area of the separator.

The second aspect of the present invention also relates to an apparatus for manufacturing the separation membrane, wherein the apparatus is a separation membrane surface treatment apparatus including a plasma light source and a first mask, wherein the first mask has an opening passing through the light source, And a blocking part for blocking off.

According to a third aspect of the present invention, in the second aspect of the present invention, the separation membrane surface treatment apparatus further comprises a second mask, wherein the second mask does not have an opening and blocks plasma passing through the first mask, Is prevented from reaching the separation membrane surface.

In a fourth aspect of the present invention, in the third aspect, each of the first mask and the second mask is hingedly connected at one end thereof, the first mask is fixed, and the second mask is fixed at a predetermined time interval So that the opening of the first mask is opened and shielded.

The present invention also relates to a method for surface treatment of a separation membrane using the apparatus described above, wherein the fifth aspect of the present invention is a method for plasma treating a predetermined portion of a surface of a separation membrane to form a plasma pattern, Wherein the surface treatment apparatus is fixed at a predetermined position and the separation membrane is continuously passed through the surface treatment apparatus, and at this time, the surface treatment apparatus of the surface treatment apparatus according to any one of the second to fourth aspects, The plasma light source is kept on.

A sixth aspect of the present invention is a plasma processing apparatus for plasma processing a predetermined portion of a separation membrane surface by plasma processing to form a plasma pattern, wherein the plasma processing is performed using a surface treatment apparatus according to the fourth aspect, Wherein the plasma light source is kept powered while the separation membrane of the surface treatment apparatus passes through the apparatus and the predetermined period of time is maintained by the operation of the second mask Plasma processing is performed in a cycle, and a plasma processing unit having a predetermined pattern is formed in the separation membrane.

The separation membrane according to the present invention has an effect that the plasma treatment is performed only on a predetermined portion of the surface, whereby the adhesion strength to the electrode is improved by the plasma treatment portion. Also, the non-plasma-treated portion prevents excessive binding of the electrode and the separator, and the untreated portion can be provided as a passage through which the electrolyte flows into the electrode assembly, thereby improving the wettability of the electrolyte. Further, the separator of the present invention does not need to have a separate adhesive layer for enhancing adhesion with an electrode. Therefore, there is an advantage that a thin-type electrochemical device can be manufactured with a low interface resistance between the electrode and the separator. Therefore, when the separator according to the present invention is applied to an electrochemical device such as a secondary battery, the output and lifetime characteristics are excellent. In addition, the separation membrane manufacturing method according to the present invention can process the patterned plasma in a continuous process, so that the process efficiency is very high.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and, together with the description of the invention given below, serve to further the understanding of the technical idea of the invention, And should not be construed as limiting. On the other hand, the shape, size, scale or ratio of the elements in the drawings incorporated herein can be exaggerated to emphasize a clearer description.
Figures 1 and 2 show schematically the surface of a membrane according to one embodiment of the present invention.
Figures 3 to 5 illustrate schematically and illustrate a method of making a separator according to the present invention.
6A and 6B illustrate a method of manufacturing a separation membrane using a surface treatment apparatus provided with first and second masks.

The terms used in the specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may properly define the concept of a term to describe its invention in its best possible way And should be construed in accordance with the principles and meanings and concepts consistent with the technical idea of the present invention. Therefore, the constitution shown in the embodiments described herein is the most preferable embodiment of the present invention and does not represent all the technical ideas of the present invention, so that various equivalents It should be understood that water and variations may be present.

Throughout this specification, when a part is referred to as being " connected " with another part, it includes not only " directly connected " but also " electrically connected " .

Throughout this specification, when an element is referred to as being "comprising", it means that it can include other elements as well, without departing from the other elements unless specifically stated otherwise.

The terms "about", "substantially", and the like used throughout this specification are used as terms of reference to and in the figures when referring to manufacturing and material tolerances inherent in the meanings mentioned, Or absolute numbers are used to prevent unauthorized exploitation by unauthorized intruders of the mentioned disclosure.

Throughout this specification, when a member is " positioned " on another member, this includes not only when a member is in contact with another member, but also when there is another member between the two members.

Throughout the present specification, the term " combination thereof " contained in the surface of the Macro-style means one or more combinations or combinations selected from the group consisting of the constituents described in the Macro-style expression, Quot; and " the "

Throughout the present specification, the description of "A and / or B" means "A or B or both".

Hereinafter, embodiments of the present invention are described in detail. However, the present invention may not be limited to the specific embodiments described below.

The present invention relates to a separation membrane for an electrochemical device having a part of the surface thereof surface-treated in order to improve an adhesion force with an electrode and to improve electrolyte wettability of the separation membrane. In one specific embodiment of the present invention, the surface treatment is formed by physical, chemical and / or electrochemical treatment for introducing a hydrophilic functional group into the organic polymer material and / or the inorganic material. In addition, the surface treatment unit is formed to have a predetermined pattern on a part of the surface of the separator, and has excellent electrolyte wettability.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic representation of a membrane according to one embodiment of the present invention. Hereinafter, a separation membrane according to the present invention will be described in detail with reference to the drawings.

The separation membrane according to one aspect of the present invention includes a porous separation membrane substrate 140 including a polymer material and a surface treatment section 120 having a predetermined pattern is formed on the surface of the outermost layer on both sides or one side of the separation membrane . In the present invention, the separation membrane serves as a porous ion-conducting barrier for passing ions while blocking electrical contact between the cathode and the anode.

According to the second aspect of the present invention, the separation membrane may further include a porous coating layer 130 on both side surfaces or one side surface of the porous separation membrane substrate 140. At this time, the surface treatment unit 120 may be formed on the surface of the porous coating layer. The porous coating layer includes a mixture of a polymer resin and inorganic particles.

Hereinafter, the separator according to the present invention is described in terms of its components.

1. Porous membrane substrate

In the present invention, the porous separator substrate can provide a path for lithium ion migration while electrically insulating the negative electrode and the positive electrode to prevent short-circuiting. The porous separator base material can be used without any particular limitation as long as it can be used as a separator material for electrochemical devices. Do. Such a porous separator substrate may be formed of a material such as a polyolefin, a polyethylene terephthalate, a polybutylene terephthalate, a polyacetal, a polyamide, a polycarbonate, a polyimide, a polyether ether ketone, a polyether sulfone, a polyphenylene oxide, And a polymer resin such as rhenium sulfide, rhenium sulfide, polyethylene naphthalene, or the like. However, it is not limited thereto. The porous separator substrate may be a laminate obtained by laminating a polymer film in the form of a sheet obtained by melting a polymer resin or a nonwoven fabric in which filaments obtained by melt spinning a polymer resin are stacked or one or more laminated.

In the present invention, the porous separator substrate may have a thickness of 3 탆 to 50 탆, or 3 탆 to 30 탆. Although the range of the porous membrane base material is not particularly limited to the above-mentioned range, if the thickness is too thin than the above-mentioned lower limit, the mechanical properties are deteriorated, and the membrane may be easily damaged during use of the battery. On the other hand, the pore size and porosity present in the porous separator substrate are also not particularly limited, but may be 0.1 탆 to 10 탆 and 25% to 85%, respectively.

2. Porous coating layer

The porous coating layer is formed as a layer on one surface or both surfaces of the porous separator substrate, and includes a mixture of a plurality of inorganic particles and a binder resin. The surface of the porous separator substrate is covered with the inorganic particles, so that the heat resistance and the mechanical properties of the separator are further improved. The porous coating layer has a microporous structure by an interstitial volume between inorganic particles, and the inorganic particles also serve as a kind of spacer capable of maintaining the physical form of the porous coating layer. In this specification, the interstitial volume means a space in which adjacent inorganic particles are substantially interfaced with each other. In addition, since the inorganic particles generally have a property that their physical properties do not change even at a high temperature of 200 ° C or more, the separator according to the present invention has excellent heat resistance by the porous coating layer. In the present invention, the porous coating layer has a thickness of 1 탆 to 50 탆, or 2 탆 to 30 탆, or 2 탆 to 20 탆.

In the porous coating layer, the content ratio of the inorganic particles to the binder resin is determined in consideration of the thickness, pore size, and porosity of the porous coating layer of the present invention, wherein the inorganic particles are contained in an amount of 50 to 99.9% 70 to 99.5 wt%, and the polymer resin is 0.1 to 50 wt% or 0.5 to 30 wt%. If the content of the inorganic particles is less than 50% by weight, the content of the polymer becomes excessively large, resulting in a reduction in the pore size and porosity due to the reduction of the void space formed between the inorganic particles. On the other hand, if it exceeds 99.9% by weight, the mechanical properties of the final porous coating layer are deteriorated due to the weak adhesion between the inorganic materials because the polymer content is too small.

According to a specific embodiment of the present invention, the inorganic particle size of the porous coating layer is not limited, but may be in the range of 0.001 to 10 탆 as much as possible for the formation of a uniform thickness coating layer and proper porosity. When the inorganic particle size satisfies this range, the dispersibility is maintained, the physical properties of the separation membrane can be easily controlled, the increase in thickness of the porous coating layer can be avoided, and mechanical properties can be improved, Due to the pore size, there is less chance of an internal short circuit occurring during battery charge / discharge.

The inorganic particles are not particularly limited as long as they are electrochemically stable. That is, the inorganic particles are not particularly limited as long as the oxidation and / or reduction reaction does not occur in the operating voltage range of the applied electrochemical device (for example, 0 to 5 V based on Li / Li +). Particularly, when inorganic particles having ion transfer ability are used, the ion conductivity in the electrochemical device can be increased to improve the performance. When inorganic particles having a high dielectric constant are used as the inorganic particles, dissociation of an electrolyte salt, for example, a lithium salt, in the liquid electrolyte is also increased, and ion conductivity of the electrolyte can be improved. In a specific exemplary embodiment of the present invention, the inorganic particles is _{BaTiO 3, Pb (Zr, Ti} ) O 3 (PZT), Pb 1 - x La x Zr 1 - y Ti y O 3 (PLZT, where 0 < x <1, 0 <y < 1 _{Im), Pb (Mg 1/3 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 , SiC, TiO ₂ , AlOOH, Mg (OH) ₂ and BaSO ₄ can be used singly or in combination of two or more. have.

The binder resin contained in the porous coating layer can be selected in consideration of improvement in mechanical properties such as flexibility and elasticity of the separation membrane. The binder resin stably fixes the adhesion between the inorganic particles, thereby contributing to prevention of deterioration of the mechanical properties of the porous coating layer finally produced. In one specific embodiment of the present invention, the binder resin may include a PVDF polymer resin and / or a (meth) acrylic polymer resin containing vinylidene fluoride (VDF) as a monomer. The binder resin may further comprise at least one binder selected from the group consisting of polyvinylpyrrolidone, polyvinylacetate, polyethylene-covinylacetate, and polyvinylpyrrolidone, in addition to the PVDF polymer resin and / or the (meth) But are not limited to, polyethylene oxide, polyarylate, cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose cyanoethylcellulose, cyanoethylsucrose, Pullulan, and carboxyl methyl cellulose. &Lt; Desc / Clms Page number 7 &gt;

On the other hand, the pore size and porosity of the porous coating layer mainly depend on the size of the inorganic particles. For example, when inorganic particles having a particle size of 1 탆 or less are used, pores to be formed also become 1 탆 or less. Such a pore structure is filled with an electrolyte solution to be injected at a later stage, and the filled electrolyte serves as an ion transfer function. Therefore, the pore size and porosity are important factors for controlling the ionic conductivity of the porous inorganic coating layer. The porosity and porosity of the porous inorganic coating layer of the present invention are preferably 0.001 to 10 μm, and preferably 5 to 95%.

In one specific embodiment of the present invention, the porous coating layer is formed by mixing the above-mentioned inorganic particles with a binder resin in a dispersion medium to prepare a slurry for the porous coating layer, applying the slurry onto the porous membrane substrate, and drying the slurry. In the present invention, the dispersion medium is not particularly limited as long as it can uniformly disperse the inorganic particles and the binder resin. Preferably, the dispersion medium is a solvent having a low boiling point and a high volatility. Examples of the solvent include acetone, toluene, cyclohexanone, cyclopentane, tetrahydrofuran, cyclohexane, xylene or N-methylpyrrolidone, Mixtures of two or more can be used. There is no limitation on the method of forming the porous coating layer by coating the slurry on the porous separator substrate. The porous coating layer may be formed by a dip coating method, a die coating method, a roll coating method, a comma coating method, , A doctor blade coat method, a reverse roll coat method, and a direct roll coat method.

3. Surface treatment section

The separation membrane according to the present invention has a surface treatment portion on a predetermined portion of the surface of the outermost layer on both sides or one side. According to a specific embodiment of the present invention, when the separation membrane according to the present invention includes a porous coating layer, the surface treatment portion may be formed on the surface of the porous separation membrane substrate and / or the surface of the porous coating layer.

The surface treatment section may be formed by combining any one or a combination of two or more of the corona discharge treatment method, ozone treatment method, atmospheric pressure plasma treatment method and ultraviolet ray irradiation method on the surface of the separation membrane, Or by atmospheric pressure plasma treatment. The polymeric resin used for the porous separation membrane substrate or the porous coating layer is generally disadvantageous in that it lacks polarity due to its chemical structure and high crystallinity and thus lacks binding characteristics. Accordingly, in the present invention, the surface of the separation membrane including the polymer resin is changed in physicochemical properties using the above-described method, thereby improving the binding force between the electrode and the separation membrane.

In the corona discharge treatment, an AC power of 50/60 Hz is converted into a direct current, and a high frequency and a high voltage are generated in the high frequency generator, so that air is ionized due to insulation breakdown and corona discharge occurs between the electrodes. When the separation membrane is passed between the two electrodes where the corona discharge is generated, a large amount of electrons flowing at this time react with the polymer on the surface.

In the plasma treatment, a plasma discharge is generated by applying a DC voltage to a conductor spaced by a certain distance to generate an electric field E, thereby forming a collision between the electrons generated from the conductor and the conductor. And the polymer on the surface of the separation membrane is reformed by passing the separation membrane between the two electrodes.

The effect of the surface treatment after the corona discharge treatment can be explained as follows. After corona discharge treatment ESCA (Electron Spectroscopy for Chemical Analysis) According to the check result, if the spectrum of the membrane containing the PVDF-HFP as a binder resin by electron collision polar functional group, such as the HOCF or the HOCF ₂ by its impact energy So that the adhesive force is improved. In addition, electrical ionization may also occur as a large amount of electrons impinge on the film surface. In addition, fine irregularities having a size of about 5 / 1,000,000 mm are formed, which lowers the contact angle of the liquid and lowers the surface tension, thereby improving the wettability to the electrolyte. The corona discharge treatment may be performed without restriction in a usual method, whereby the discharge amount is, for example, but may use a range, or a range of 50 to 120Wmin / m ² of 30 to 300 Wmin / m ^2, this limited It is not.

The surface treatment may be performed using an ozone treatment method or an ultraviolet ray irradiation method, which is a method of oxidizing the surface of the polymer resin by contacting the ozone generated in the ozone generator. If the surface treatment portion is formed on the surface of the separation membrane by the above-described method, the surface is modified to have a polar functional group and improve the adhesion to the electrode. Particularly, when the electrode mixture contains an aqueous binder using an aqueous dispersion medium, the surface adhesion to the electrode layer formed by the aqueous system is improved and the binding force is improved.

In the present invention, it is preferable that the surface treatment portion is formed in an area of less than 90%, less than 80%, less than 70%, less than 60%, or less than 50% of the surface area of the separation membrane. When the surface treatment portion is excessively over the above-mentioned range, the electrode and the separator are excessively brought into close contact with each other and the electrolyte solution is not smoothly moved, resulting in deterioration of electrolyte wettability and poor output characteristics and interfacial resistance characteristics.

In the present invention, the surface treatment unit may be formed to have a predetermined pattern on a part of the surface of the separation membrane. According to a specific embodiment of the present invention, the surface treatment section may be formed in a belt shape having a predetermined width at a rim portion (an outer peripheral portion, an edge portion) of the separation membrane surface.

In addition, according to a specific embodiment of the present invention, the predetermined pattern may be regularly repeated so that the surface treatment unit exhibits uniform electrolyte wettability and interface resistance characteristics over the entire surface of the separation membrane. For example, the surface treatment section may be formed in a pattern in which a plurality of stripes are spaced apart at predetermined intervals. In the case of a stripe pattern, the width of the stripe may be, for example, 0.5 to 50 mm.

FIG. 2 is an exemplary illustration of another pattern of the surface treatment section 120 according to one embodiment of the present invention. However, the pattern of the surface treatment unit is not limited to any specific shape, and may be implemented in various embodiments within the scope of the present invention.

Next, a method for producing a separation membrane having the above-described characteristics, particularly, a method for treating the surface of the separation membrane will be described in more detail.

The separation membrane according to the present invention is characterized in that it is produced by a continuous process in which plasma is continuously discharged from a plasma light source.

According to one specific embodiment of the present invention, the separation membrane manufacturing method is a method for manufacturing a separation membrane, for example, by fixing a position of a plasma light source, continuously discharging plasma (on state) (See Fig. 3). Or by fixing the separation membrane to be subjected to the plasma surface treatment and moving the plasma light source from one end to the other end of the separation membrane (see FIG. 4).

Typically, the separator is produced in a film shape having a large aspect ratio and is rolled up and stored. Therefore, the film-type separator may be rolled in a take-up roll, surface-treated through a light source, and then put into a battery manufacturing process or rewound and stored in a roll form. FIG. 5 illustrates a method of fabricating a separation membrane having a plasma light source fixed according to an embodiment of the present invention. When a film type separation membrane is prepared and wound and stored, the separation membrane is sequentially moved from the extraction roller to the winding roller, (See Fig. 5).

In one embodiment of the present invention, it is preferable that the light source has a length longer than the width of the separation membrane, and is plasma-processed in a uniform pattern over the entire width of the separation membrane.

In a specific embodiment of the present invention, the plasma light source may include a mask having at least one opening. The opening in the mask is a through hole through which the plasma light source can pass. In this specification, a portion of the mask other than the opening where the through hole is formed is referred to as a shielding portion. The mask is disposed between the plasma light source and the separation membrane, and the plasma emitted from the plasma light source is passed / shielded according to the pattern of the opening formed in the mask, so that the separation membrane has a processing unit with a predetermined pattern according to the opening pattern of the mask. A part of the plasma emitted from the plasma light source passes through the opening to reach the surface of the separation membrane and some plasma can not be blocked by the shielding portion other than the opening portion to reach the separation membrane. FIG. 6 schematically illustrates a process of performing a plasma process using a mask having at least one opening. FIG. The mask 210 has a plurality of openings 211, and a predetermined region of the separator through which the plasma passes through the openings is plasma-processed. The remaining portion, that is, the shielding portion 212, The portion where the light source is blocked by the mask is not plasma-treated.

According to another embodiment of the present invention, the light source may further include a first mask having an opening portion and a second mask having no opening portion. The second mask shields the plasma so that the plasma light source passing through the opening of the first mask is not projected onto the separation membrane.

6A is a schematic diagram illustrating a plasma apparatus having a second mask and a method of treating a surface of the separation membrane using the same. Referring to FIG. 2, a first mask 310 and a second mask 320 are sequentially disposed between the light source and the separation membrane, and the second mask is periodically inserted and removed at predetermined time intervals. The second mask may be configured such that no openings are formed, or that the plasma that has passed through the first mask does not reach the separation membrane.

6B is a schematic view of a mask to which a first mask and a second mask are connected. The first and second masks are connected by a hinge fastener 330. The second mask 320 is horizontally disposed on the lower surface of the first mask 310 and horizontally maintained for a predetermined period of time to block the light source and then the second mask is hingedly rotated, Lt; / RTI &gt; Thereby allowing the plasma emitted from the plasma light source to reach the separator for a certain period of time.

In a specific embodiment of the present invention, the second mask may be connected through a predetermined fastener so as to be pivotally rotated at an angle of 90 to 180 degrees with respect to the first mask. For example, one end of the first mask and one end of the second mask may be connected using a fastener, for example, a hinge. Then, the first mask is fixed, and the plasma can be passed or blocked in such a manner that the opening is opened and closed in such a manner that the second mask is rotated and opened by the hinge.

As described above, by using the second mask to periodically block the light source at predetermined time intervals, the power source is continuously applied to the light source, so that the patterned surface treatment can be performed without turning on / off the power source. The separation membrane manufacturing process according to the present invention can perform the plasma treatment while maintaining the uniform strength over the entire surface of the separation membrane, compared to turning on / off the light source. Therefore, the separation membrane according to the present process can exhibit a uniform adhesion improving effect over the entire separation membrane.

The thus-prepared separator of the present invention can be used as a separator of an electrochemical device, and the present invention provides an electrochemical device including the separator. The electrochemical device includes all devices that perform an electrochemical reaction, and specific examples thereof include all kinds of primary, secondary, fuel cell, solar cell, and capacitor. 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.

In one specific embodiment according to the present invention, the lithium secondary battery can be manufactured according to a conventional method known in the art. According to one embodiment of the present invention, an electrode assembly is prepared by interposing the above-described separation membrane between an anode and a cathode, charging the electrode assembly into a battery case, and then injecting an electrolyte to manufacture a secondary battery

can do.

In one embodiment of the present invention, the electrode of the secondary battery may be manufactured by adhering an electrode active material to an electrode current collector according to a conventional method known in the art. Examples of the cathode active material include, but are not limited to, lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium iron oxide, A lithium intercalation material such as a composite oxide formed by a combination thereof, and the like are preferable. As a non-limiting example of the negative electrode active material, a conventional negative electrode active material that can be used for a negative electrode of an electrochemical device can be used. In particular, lithium metal or a lithium alloy, carbon, petroleum coke, activated carbon, Lithium-adsorbing materials such as graphite or other carbon-based materials and the like are preferable. Non-limiting examples of the positive current collector include aluminum, nickel, or a combination thereof. Examples of the negative current collector include copper, gold, nickel, or a copper alloy or a combination thereof Foil to be manufactured, and the like.

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 -, NCF 3 SO 2) 2 -, (CF 2 SO 2) 3 ^- , anion such as anion, or a combination thereof, is preferably selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (NMP), ethylmethyl carbonate (EMC), gamma-butyrolactone (gamma -butyrolactone), or a mixture of these solvents. , And the like, but the present invention is not limited thereto.

The electrolyte injection may be performed at an appropriate stage of the battery manufacturing process, depending on the manufacturing process and required properties of the final product. That is, it can be applied before assembling the cell or at the final stage of assembling the cell. As a process for applying the electrode assembly of the present invention to a battery, a lamination, stacking and folding process of a separator and an electrode can be performed in addition to a general winding process.

The present invention also provides a battery module including the electrochemical device as a unit cell, a battery pack including the battery module, and a device including the battery pack as a power source.

At this time, specific examples of the device include a power tool that is powered by an electric motor and moves; An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and the like; An electric motorcycle including an electric bike (E-bike) and an electric scooter (E-scooter); An electric golf cart; And a power storage system, but the present invention is not limited thereto.

Hereinafter, the present invention will be described in further detail with reference to the following examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

Example

Production Example 1: Preparation of Separation Membrane

Polyvinylidene fluoride-hexafluoropropylene (containing 20 mol% of hexafluoropropylene) having a solubility of 20% by weight based on acetone at 35 DEG C, polyvinylidene fluoride having a solubility of 5% by weight based on acetone at 35 DEG C Fluoro-chlorotrifluoroethylene (containing 8 mol% of chlorotrifluoroethylene) and cyanoethylflurane were added to acetone at a weight ratio of 8: 2: 2, respectively, and dissolved at 50 DEG C for at least 12 hours to obtain a binder polymer Solution. Al2O3 and BaTiO3 powder mixed at a weight ratio of 9: 1 were added to the prepared binder polymer solution so that the binder polymer / inorganic particles = 20/80 weight ratio, and the inorganic powder was crushed and dispersed for 12 hours or more using a ball mill To prepare a slurry. The slurry thus prepared was coated on a polyethylene porous substrate having a width of 10 cm by dip coating and dried to obtain a separation membrane. At this time, the coating thickness of the porous coating layer was adjusted to about 5 탆 each on both sides.

Production Example 2: Preparation of negative electrode

3 wt.% And 1 wt.%, Respectively, of carbon powder as a negative electrode active material, styrene butadiene rubber (SBR) as a binder, carboxymethyl cellulose (CMC) as a dispersant and carbon black as a conductive material, Was added to the solvent N-methyl-2-pyrrolidone (NMP) to prepare a negative electrode mixture slurry. The negative electrode mixture slurry was applied to a copper (Cu) thin film as an anode current collector having a thickness of 8 占 퐉 and dried to produce a negative electrode, followed by roll pressing. The loading amount of the negative electrode active material was 380 mg / 25 cm ² .

Production Example 3: Preparation of positive electrode

95% by weight of a lithium manganese composite oxide as a positive electrode active material, 2% by weight of carbon black as a conductive material, and 3% by weight of PVDF as a binder were added to N-methyl-2-pyrrolidone (NMP) . The anode mixture slurry was applied to an aluminum (Al) thin film of a cathode current collector having a thickness of 12 탆 and dried to produce a cathode, followed by roll pressing. The loading amount of the positive electrode active material was 680 mg / 25 cm ² .

Example 1

The surface of the separation membrane obtained by the method according to Production Example 1 was subjected to corona treatment at a discharge amount of 80 Wmin / m ² to form a surface treatment portion of a stripe pattern. The width of the stripe was 20 mm and the spacing between them was 20 mm. The area ratio of the surface-treated portion was set to 50%. The separator obtained in this manner and the negative electrode and the positive electrode according to 2 to 3 above were laminated in the order of separator / cathode / separator / anode, laminated to prepare a mono cell, the mono cell was charged into the case, (Ethylene carbonate: propylene propionate 6: 4 (volume ratio), LiPF ₆ 1M) to prepare a secondary battery. At this time, the capacity of the battery was 78 A and the ratio of the anode / cathode capacity (NP ratio) was 108%.

Example 2

The surface of the separation membrane obtained by the method according to Production Example 1 was subjected to corona treatment at a discharge amount of 80 Wmin / m ² to form a surface treatment portion. The width of the stripe was 20 mm and the spacing between them was 20 mm. The area ratio of the surface-treated portion was set to 66%. The separator obtained in this manner and the negative electrode and the positive electrode according to 2 to 3 above were laminated in the order of separator / cathode / separator / anode, laminated to prepare a mono cell, the mono cell was charged into the case, (Ethylene carbonate: propylene propionate 6: 4 (volume ratio), LiPF ₆ 1M) to prepare a secondary battery. At this time, the capacity of the battery was 78 A and the ratio of the anode / cathode capacity (NP ratio) was 108%.

Comparative Example 1

A separation membrane was prepared in the same manner as in Example 1, except that corona discharge treatment was performed on the entire surface of the separation membrane obtained by the method according to Production Example 1. [ The separator obtained in this manner and the negative electrode and the positive electrode according to 2 to 3 described above were laminated in the order of separator / cathode / separator / anode and laminated to prepare a mono-cell, .

Comparative experiment results

1) Wetting test

The electrolytic solution was put into the container to a height of 1 cm. The monocells obtained in Example 1, Example 2 and Comparative Example 1 were immersed therein and left for 1 hour. The height of the monocell was 10 cm. Then, the heights of the electrolyte impregnated in the mono-cells were measured and summarized as shown in Table 1 below. As can be seen from the table below, it was confirmed that the impregnation property of the monocell of Example 2 was the most excellent.

Example 1 Example 2 Comparative Example 1 Wetting Height
(After 1 hour) 2.2cm 3.8cm 2.0cm

2) Adhesion test result

The separation membrane obtained in each of the Examples and Comparative Examples and the cathode in Production Example 2 were laminated by hot pressing at 90 DEG C under a pressure of about 15 MPa for 1 second to prepare an adhesive force test sample. At this time, the dimensions of the prepared sample were 60x15 mm. Adhesion was measured using a peel tester (180 degree) instrument. As a result, it was confirmed that the adhesive strength of Comparative Example 1 was excessively high as compared with the Examples.

Example 1 Example 2 Comparative Example 1 Adhesion 83gf / 15mm 82gf / 15mm 90gf / 15mm

3) Resistance characteristic test result

The resistance characteristics of each battery were evaluated using the batteries manufactured in Examples 1 and 2 and Comparative Example 1. [ When a current of 200 A was flown for 30 seconds at a capacity of 50% (SOC) of each battery, the resistance value at a point of 10 seconds was confirmed. At that time, the capacity of the battery was 78 Ah.

Example 1 Example 2 Comparative Example 1 Resistance (mohm) 1.60 1.38 1.72

4) Capacity retention rate test results

The batteries of Examples 1 and 2 and Comparative Example 1 were charged in a CC-CV mode at a rate of 1 / 3C to 4.25V under a temperature condition of 45 DEG C, discharged at a constant current up to 3V at 1 / 3C, The capacity retention rate was confirmed. The capacity retention rate was calculated by the following formula 1.

<Formula 1>

Capacity retention rate (%) = [300th cycle discharge capacity / second cycle discharge capacity] X 100

Example 1 Example 2 Comparative Example 1 Capacity retention rate (%)
(after 300 cycles) 80.3 83.1 78.1

Claims (6)

As a separation membrane for an electrochemical device,
A surface treatment section having a predetermined pattern is formed on the surface of the outermost layer on both sides or one side of the separation membrane by at least one process selected from the group consisting of corona discharge, atmospheric pressure plasma, ozone treatment, and ultraviolet irradiation, Wherein the surface treatment portion is a checkerboard pattern formed by crossing a stripe pattern and / or each stripe, wherein the surface treatment portion is less than 50% of the total surface area of the separator.
A separation membrane surface treatment apparatus comprising a plasma light source and a first mask, wherein the first mask is provided with an opening passing through the light source and a blocking section for blocking.
3. The method of claim 2,
Wherein the separation membrane surface treatment apparatus further comprises a second mask wherein the second mask is not provided with an opening and blocks plasma passing through the first mask to prevent plasma from reaching the surface of the separation membrane, Device.
The method of claim 3,
Wherein the first mask and the second mask are hingedly connected at their respective one ends and the first mask is fixed and the second mask is operated to open and shield the openings of the first mask at predetermined time intervals , Surface treatment apparatus.
A predetermined portion of the separation membrane surface is subjected to plasma treatment to form a plasma pattern,
Wherein the plasma treatment is performed using the surface treatment apparatus according to any one of claims 2 to 4,
Wherein the surface treatment apparatus is fixed at a predetermined position and the separation membrane continuously passes through the surface treatment apparatus, wherein the plasma light source of the surface treatment apparatus is maintained in an on state.
A predetermined portion of the separation membrane surface is subjected to plasma treatment to form a plasma pattern,
Wherein the plasma treatment is performed using the surface treatment apparatus according to claim 4,
The surface treatment apparatus is fixed at a predetermined position and the separation membrane is continuously passed through the surface treatment apparatus. While the separation membrane of the surface treatment apparatus passes through the apparatus, the plasma light source is maintained in the power- Wherein a plasma processing section having a predetermined pattern is formed in the separation membrane at a predetermined time interval by the operation of the plasma processing section.

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