KR101856870B1 - Polymer composite with improved adhesion and method for producing thereof - Google Patents

Abstract

The present invention relates to a polymer composite, and a manufacturing method thereof. According to the manufacturing method of one embodiment of the present invention, the polymer composite can be formed by forming inorganic thin membrane on at least one surface of a polymer base material and processing radiation treatment on the inorganic thin membrane. Therefore, adhesion between the polymer base material and the inorganic thin membrane can be increased.

Description

TECHNICAL FIELD [0001] The present invention relates to a polymer composite having improved adhesion and a method of manufacturing the polymer composite.

TECHNICAL FIELD The present invention relates to a polymer composite having increased adhesion between a polymer substrate and an inorganic thin film layer by irradiating an inorganic thin film layer formed on at least one side of the polymer substrate with radiation, and a method for producing the same.

Recently, interest in energy storage technology is increasing. As the application fields of cell phones, camcorders, notebook PCs and even electric vehicles are expanding, efforts for research and development of electrochemical devices are becoming more and more specified. The electrochemical device is one of the most attracting fields in this respect. Of these, the development of a rechargeable secondary battery has become a focus of attention. Recently, in developing such a battery, Research and development on the design of electrodes and batteries are underway.

The lithium secondary battery is composed of a positive electrode, a negative electrode, a separator, and an electrolyte. Such a lithium secondary battery may cause a malfunction according to an operating environment. If a thermal runaway occurs due to overheating during a malfunction, There is a possibility that an internal explosion may be generated due to the discharge of electric energy due to the potential difference of the electrode which is sharply narrowed and the vaporization of the electrolytic solution thereby.

As a separator material for a lithium secondary battery, a polyolefin-based polymer base material having mechanical properties and chemical stability suitable for small-sized mobile devices and a polymer composite in which an inorganic inorganic thin film layer is formed on one side or both sides of a polymer base material is mainly used.

However, the polymer composite has a low heat stability due to heat shrinkage at a high temperature, and there is a risk of an internal short circuit due to weak mechanical strength for application to medium and large electrochemical devices. That is, thermal runaway due to overheating can occur and the polymer substrate and the inorganic thin film layer can be separated.

When the polymer complex is separated, the potential difference is rapidly narrowed due to an internal short circuit, resulting in a fear of internal explosion due to electric energy discharge and vaporization of the electrolyte.

Further, there is a problem that it is difficult to obtain a tight coating between the polymer substrate and the inorganic thin film layer, and it is difficult to obtain a hard coating result.

Korean Patent Registration No. 10-1506221, "Solid Electrolyte-Method for Producing Lithium Ion Conducting Polymer Composite Film"

The present invention provides a polymer composite in which an inorganic thin film layer is deposited on at least one surface of a polymer substrate, and then the adhesion between the polymer substrate and the inorganic thin film layer is increased by irradiating the inorganic thin film layer with radiation.

The method of producing a polymer composite according to an embodiment of the present invention includes the steps of depositing an inorganic thin film layer on at least one surface of a polymer substrate and irradiating the inorganic thin film layer with radiation to increase the adhesive force through chemical bonding between the polymer substrate and the inorganic thin film layer .

The radiation may be e-beam, gamma-rays, or x-ray.

The radiation dose may be between 1 kGy and 100 kGy.

The inorganic thin film layer may be SiO ₂ or Al ₂ O ₃ .

The inorganic thin film layer may be formed of a material selected from the group consisting of WO ₃ , MnO ₂ , Fe ₂ O ₃ , Fe ₃ O ₄ , BaTiO ₃ , Pb (Zr, Ti) O ₃ (PZT), HfO ₂ , SrTiO ₃ , CeO ₂ , MgO, NiO, ZrO ₂ , Y ₂ O ₃ , and TiO ₂ .

In the step of depositing the inorganic thin film layer, the inorganic thin film layer may be formed by a chemical vapor deposition (CVD) method, an atomic layer deposition (ALD) method, a chemical solution deposition method (CBD) thermal evaporation deposition, or the like.

The inorganic thin film layer may have a thickness of 1 nm to 1 占 퐉.

The polymeric substrate may be selected from the group consisting of polyethylene, polypropylene, polystyrene, polypropylene terephthalate, polyethylene terephthalate, polybutylene terephthalate, polyacrylamide Polyacrylamide, polyester, polyacetal, polyamide, polycarbonate, polyimide, polyether ether ketone, polyether sulfone, At least one selected from the group consisting of polyphenylene oxide, polyphenylene sulfide, polyethylene naphthalene, and polyolefin can be used.

Wherein the polymer substrate is porous.

The thickness of the polymer base material may be 1 [mu] m to 50 [mu] m.

A polymer composite for an electrochemical device is prepared by the method for producing a polymer composite according to an embodiment of the present invention.

According to an embodiment of the present invention, an inorganic thin film layer is deposited on at least one side of a polymer substrate, and the inorganic thin film layer is irradiated with radiation to improve adhesion force through chemical bonding (covalent bonding) between the polymer substrate and the inorganic thin film layer .

The polymer composite according to the embodiment of the present invention can improve the binding property between the inorganic thin film layer and the polymer substrate by forming an inorganic thin film layer which is not inorganic particles on the polymer substrate.

The polymer composite according to the embodiment of the present invention can improve the thermal stability.

The polymer composite according to an embodiment of the present invention can improve the high-rate charge / discharge characteristics of an electrochemical device when used in an electrochemical device such as a lithium secondary cell, and improve the stability of an electrochemical device at a high temperature .

1 is a cross-sectional view illustrating a polymer composite in which an inorganic thin film layer is formed on one side according to an embodiment of the present invention.
2 is a cross-sectional view illustrating a polymer composite in which an inorganic thin film layer is formed on both sides according to an embodiment of the present invention.
3 is a view showing a structure of a polymer composite according to an embodiment of the present invention.
4A to 4D are images showing a scanning electron microscope (SEM) of the surface of a polymer composite according to an embodiment of the present invention.
5 is an image showing a scanning electron microscope (SEM) of the surface of the polymer composite according to Comparative Example 1. Fig.
6 is an image showing the heat shrinkage rate behavior of the polymer composite according to the embodiment of the present invention.
7 is a graph showing transmittance of a polymer composite according to an embodiment of the present invention.
8 is a graph showing charge / discharge characteristics of a lithium secondary battery including a polymer composite (separator) according to an embodiment of the present invention.

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

The terminology used herein is for the purpose of illustrating embodiments and is not intended to be limiting of the present invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. &Quot; comprises "and / or" comprising "when used in this specification do not exclude the presence or addition of one or more other elements, steps, or elements.

As used herein, the terms "embodiment," "example," "side," "example," and the like should be construed as advantageous or advantageous over any other aspect or design It does not.

Also, the term 'or' implies an inclusive or 'inclusive' rather than an exclusive or 'exclusive'. That is, unless expressly stated otherwise or clear from the context, the expression 'x uses a or b' means any of the natural inclusive permutations.

Also, the phrase "a" or "an ", as used in the specification and claims, unless the context clearly dictates otherwise, or to the singular form, .

The terms used in the following description are chosen to be generic and universal in the art to which they are related, but other terms may exist depending on the development and / or change in technology, customs, preferences of the technician, and the like. Accordingly, the terminology used in the following description should not be construed as limiting the technical thought, but should be understood in the exemplary language used to describe the embodiments.

Also, in certain cases, there may be a term chosen arbitrarily by the applicant, in which case the detailed description of the meaning will be given in the corresponding description section. Therefore, the term used in the following description should be understood based on the meaning of the term, not the name of a simple term, and the contents throughout the specification.

On the other hand, the terms first, second, etc. may be used to describe various elements, but the elements are not limited by terms. Terms are used only for the purpose of distinguishing one component from another.

Further, when a portion of a film, a layer, a configuration request, or the like is referred to as being "on" or "on" another portion, not only the case where the portion is directly on another portion but also another film, layer, And the like.

Hereinafter, the present invention will be described in detail with reference to the drawings.

1 is a cross-sectional view of a polymer composite formed on one side of an inorganic thin film layer according to an embodiment of the present invention.

1, in the polymer composite of the present invention, an inorganic thin film layer 120 is formed on one side of a polymer substrate 110.

The polymer substrate 110 may be formed of a material selected from the group consisting of polyethylene, polypropylene, polystyrene, polypropylene terephthalate, polyethylene terephthalate, polybutylene terephthalate, poly Polyacrylamide, polyester, polyacetal, polyamide, polycarbonate, polyimide, polyether ether ketone, polyether sulfone, sulfone, sulfone, polyphenylene oxide, polyphenylene sulfide, polyethylene naphthalene, and polyolefin. The term " polyphenylene sulfide "

The polymeric substrate 110 may be in the form of a commercially available porous substrate or non-woven.

A commercially available substrate may be used as the polymer substrate 110, and commercially available polyethylene or commercially available polypropylene may be used. Since the polymer substrate 110 made of polyethylene, commercial polypropylene or a combination thereof has a small pore size, it is preferable that the inorganic thin film layer 120 is formed on both sides and inside of the polymer substrate 110, Can be further improved.

Further, the polymer substrate 110 may be a substrate of a polymer produced by a stretching process or a nonwoven fabric-like substrate formed of a porous net structure by crossing of nanofibers.

For example, the polymeric substrate 110 may have a continuous porous structure with a uniform pore size distribution.

Use of such a porous polymer substrate 110 can exhibit excellent high rate charge / discharge characteristics and high ion transfer characteristics of an electrochemical device.

In addition, the nonwoven fabric used as the polymer substrate 110 has a very large pore size and can serve as a skeleton in which the inorganic thin film layer 120 is formed.

If the inorganic thin film layer 120 is formed on at least one surface of the nonwoven fabric, the inorganic thin film layer 120 having voids of several tens to several hundreds of nanometers may be formed on the surface of the nonwoven fabric, May also be formed in the interior of the polymer substrate 110.

The thickness T1 of the polymer substrate 110 is 1 to 50 占 퐉 and it is difficult to maintain the mechanical properties when the thickness T1 of the polymer substrate 110 is 1 占 퐉 or less. There is a problem that resistance increases in a chemical device.

The inorganic thin film layer 120 according to an embodiment of the present invention may be formed of a material selected from the group consisting of WO ₃ , MnO ₂ , Fe ₂ O ₃ , Fe ₃ O ₄ , BaTiO ₃ , Pb (Zr, Ti) O ₃ (PZT), HfO ₂ , SrTiO ₃ , CeO ₂ It can be MgO, NiO, CaO, ZnO, ZrO _2, Y ₂ O _3, and at least one selected from the group consisting of TiO ₂ or more.

Preferably, the inorganic thin film layer 120 may be SiO ₂ or Al ₂ O ₃ , thereby being electrochemically stable and allowing easy vapor deposition on the polymer substrate 110.

The thickness T2 of the inorganic thin film layer 120 is preferably 1 nm to 1 占 퐉 and when the thickness T2 of the inorganic thin film layer 120 is 1 nm or less, thermal characteristics at a high temperature can not be maintained, The thickness of the inorganic thin film layer 120 may be increased to increase the resistance of the electrochemical device as a whole, thereby deteriorating the performance of the electrochemical device. This may increase the deposition process time and decrease the mass productivity.

When the inorganic thin film layer 120 is formed on the polymer substrate 110, the inorganic thin film layer 120 is diffused and permeates into the interior of the polymer substrate 110. Accordingly, the inorganic thin film layer 120 is formed on the outer surface of the polymer substrate 110, but may also be formed on the inside thereof.

The inorganic thin film layer 120 may be formed on both sides of the polymer substrate 110. The inorganic thin film layer 120 may be formed on both sides of the polymer substrate 110. [ In the case where the inorganic thin film layer 120 is formed only on one side of the polymer substrate 110, the thermal stability of the polymer complex may not be sufficient although the process is simple. However, when the inorganic thin film layer 120 is formed on both surfaces of the polymer substrate 110, the process is somewhat complicated, but the thermal stability of the polymer composite material can be greatly improved.

Hereinafter, the polymer composite in which the inorganic thin film layer 120 is formed on both sides of the polymer substrate 110 will be described.

2 is a cross-sectional view illustrating a polymer composite in which an inorganic thin film layer is formed on both sides according to an embodiment of the present invention.

Referring to FIG. 2, in the polymer composite of the present invention, an inorganic thin film layer 120 is formed on the inside or both sides of the polymer substrate 110.

The components of the polymer composite forming the inorganic thin film layer 120 on both sides of the polymer substrate 110 may include the same technical components as those of the polymer composite according to the embodiment of the present invention described above with reference to FIG. 1, Duplicate description will be omitted for the constituent elements.

When the inorganic thin film layer 120 is formed on both sides of the polymer substrate 110, the contact area between the polymer substrate 110 and the inorganic thin film layer 120 is greatly improved. As a result, the dimensional stability and heat resistance of the polymer composite at high temperatures are greatly improved.

3 is a flow chart illustrating a method for producing a polymer composite including an inorganic thin film layer according to an embodiment of the present invention.

Referring to FIG. 3, a method for producing a polymer composite according to an embodiment of the present invention will be described.

First, Step S210 is a step of depositing an inorganic thin film layer on at least one side of the polymer substrate.

It is preferable that the thickness T1 of the polymer base material is in the range of 1 탆 to 50 탆 and it is difficult to maintain the mechanical properties when the thickness T1 of the polymer base material is 1 탆 or less, And acts as a resistance layer that causes performance degradation.

The polymer substrate may further include, but is not limited to, introducing a hydrophilic functional group to the surface of the polymer substrate and the inner surface of the pores using an oxygen plasma before forming the inorganic thin film layer.

The hydrophilic functional group may comprise -OH or -COOH. The hydrophilic functional group can maximize the effect of irradiation by improving the affinity with the precursor used in the inorganic thin film layer deposition.

The thickness of the inorganic thin film layer is preferably 1 nm to 1 占 퐉.

When the thickness of the inorganic thin film layer is less than 1 탆, thermal characteristics at high temperature can not be maintained. When the thickness of the inorganic thin film layer exceeds 1 탆, the thickness of the inorganic thin film layer increases, There is a fear that the polymer substrate may become brittle due to an increase in the content of the inorganic substance.

The inorganic thin film layer may be formed by at least one of chemical vapor deposition (CVD), atomic layer deposition (ALD), chemical bath deposition (CBD), and thermal evaporation deposition .

Preferably, the inorganic thin film layer can be formed using a chemical vapor deposition method or an atomic layer deposition method.

Chemical vapor deposition or, or atomic layer deposition according to embodiments of the present invention as a precursor for forming the metal thin film layer _{SiCl 4 (silicon tetrachloride), TEMASi} (tetrakis-ethyl-methyl-amino-Silcon), TiCl 4 (titanium chloride ), TTIP (titanium-tetrakis-isopropoxide), TEMAT (tetrakis-ethyl-methyl-amino-titanium), TDMAT (tetrakis- amino-titanium, tetrakis-diethylamino-titanium, tri-methyl-aluminum, MPTMA, ethyl-pyridine-triethyl-aluminum, EPPDMAH (ethyl-pyridine-dimethyl-aluminum hydride), IPA (C ₃ H ₇ -O) ₃ Al), TEMAH (tetrakis-ethyl-methyl- amino- hafnium), TEMAZ TDMAH (tetrakis-dimethylamino-hafnium), TDMAZ (tetrakis-dimethyl-amino-zirconium), TDEAH (tetrakis-diethylamino- hafnium), TDEAZ (tetrakis- diethylamino- zirconium), hafnium tetra-tert -butoxide), ZTB (zirconium tetra-tert-b _{utoxide), HfCl 4 (hafnium chloride} ), Ba (C 5 H 7 O 2) 2, Sr (C 5 H 7 O 2) 2, Ba (C 11 H 19 O 2) _{2, Sr (C 11 H 19} O 2) 2, Ba (C 5 HF 6 O 2) 2, Sr (C 10 H 10 F 7 O 2) 2, Ba (C 10 H 10 F 7 O 2) 2, _{Sr (C 10 H 10 F 7} O 2) 2, Ba (C 11 H 19 O 2) -CH 3 (OCH 2 CH 2) 4 OCH 3, Sr (C 11 H 19 O 2) 2 -CH 3 (OCH _{2 HC 2) 4 OCH 3)} , Ti (OC 2 H 5) 4, Ti (OC 3 H 7) 4, Ti (OC 4 H 9) 4, Ti (C 11 H 19 O 2) 2 (OC 3 H _{7) 2, Ti (C 11} H 19 O 2) 2 (O (CH 2) 2 OCH 3) 2, Pb (C 5 H 7 O 2) 2, Pb (C 5 HF 6 O 2) 2, Pb ( _{C 5 H 4 F 3 O 2} ) 2, Pb (C 11 H 19 O 2) 2, Pb (C 11 H 19 O 2) 2, Pb (C2H 5) 4, La (C 5 H 7 O 2) 3 _{, La (C 5 HF 6 O} 2) 3, La (C 5 H 4 F 3 O 2) 3, La (C 11 H 19 O 2) 3, Zr (OC 4 H 9) 4, Zr (C 5 HF _{6 O 2) 2, Zr (} C 5 H 4 F 3 O 2) 4, Zr (C 11 H 19 O 2) 4, Zr (C 11 H 19 O 2) 2 (OCH 3 H 7) 2, TMSTEMAT ( _{MeSiN = Ta (NEtMe) 3)} , TBITEMAT (Me 3 CN = Ta (NEtME) 3), TBTDET (Me 3 CN = Ta (Net 2) 3), PEMAT (Ta [N (CH 3) (C 2 H 5 ) ₅ ], PDEAT (Ta [N (C ₂ H ₅ ) ₂ ] ₅ ), PDMAT (Ta [N (CH ₃ ) ₂ ] ₅ , TaF ₅ , Can include But, it is not limited.

The chemical vapor deposition method according to an embodiment of the present invention may be performed at room temperature and atmospheric pressure, but the present invention is not limited thereto.

The chemical vapor deposition method for forming the inorganic thin film layer may be performed in an oxidizing atmosphere, but may not be limited thereto. For example, a chemical vapor deposition method for forming an inorganic oxide thin film may be performed by depositing a polymer substrate in a CVD reactor and then supplying an appropriate inorganic precursor and an oxygen-containing gas together to react to form a nanometer-level thickness on the outer surface and pore surface of the polymer substrate To form an inorganic oxide thin film on the substrate.

The oxygen-containing gas may include, but is not limited to, water vapor, oxygen, air, ozone, or combinations thereof.

The chemical vapor deposition method for forming the inorganic thin film layer can utilize the inorganic precursor and the reaction conditions conventionally used for the formation of the inorganic oxide thin film layer. In addition, as a method for simultaneously improving the thermal properties while inheriting excellent mechanical properties of the existing polymer composite, Can be used without particular limitation as long as it is a condition capable of producing the polymer complex in which the polymer is formed.

Atomic layer deposition is generally performed by chemically adsorbing a precursor (molecule) onto the surface of a substrate using a chemical bond with the substrate surface, and then substituting, burning, and protonating the adsorbed precursor through a surface chemical reaction with the next precursor. (Cyclic repetition). Thus, it is possible to deposit a layer-by-layer, and the oxide can be deposited as thin as possible.

The atomic layer deposition method according to an embodiment of the present invention can form a metal oxide thin film through a low temperature atomic layer deposition method, but is not limited thereto.

The low-temperature atomic layer deposition may be performed at a temperature ranging from about 25 캜 to less than about 100 캜, but is not limited thereto.

Since the inorganic thin film layer is deposited at a relatively low temperature, it is possible to prevent pore collapse and particle generation of the porous polymer substrate, which may occur in the case of performing a high temperature process.

By forming the inorganic thin film layer to a thickness of nanometer level on the surface of the polymer substrate and the surface of the pores using the low-temperature atomic layer deposition method, the thermal characteristics can be improved while maintaining the excellent mechanical properties and high ion mobility of the conventional polymer composite, It is possible to produce a polymer composite of a thin thickness capable of high-density charging while reducing the electrical resistance acting thereon.

In addition, the electrochemical device having such an electrochemical device can increase the volume of a limited electrode active material in the device, thereby increasing the capacity.

In the atomic layer deposition method, when the temperature is higher than 100 ° C, the polymer complex itself is damaged during the process and the polymer complex shrinks, whereas at low temperatures, the polymer composite does not shrink. In general, unlike the conventional process using atomic layer deposition at a temperature of 100 ° C or higher, a low temperature atomic layer deposition process at a low temperature, that is, below 75 ° C or 70 ° C is used to cause a chemical decomposition reaction of an inorganic precursor, Layer) can be densely formed on the substrate, and the polymer composite formed by such low-temperature atomic layer deposition does not show a change in thickness.

The polymer composite according to the embodiment of the present invention can improve the binding property between the inorganic thin film layer and the polymer substrate by forming an inorganic thin film layer which is not inorganic particles on the polymer substrate.

Thereafter, in step S220, the step of irradiating the inorganic thin film layer with radiation is performed to increase the adhesive force between the polymer substrate and the inorganic thin film layer.

The radiation may be e-beam, gamma-rays or x-ray, and preferably an e-beam may be used.

The radiation dose may be from 1 kGy to 100 kGy, preferably from 10 kGy to 50 kGy.

If the irradiation dose is less than 1 kGy, there is a problem that the binding by radiation does not proceed, and when the irradiation dose is more than 100 kGy, the polymer complex is destroyed.

The inorganic thin film layer undergoes a bonding reaction in which a Si-OC, Si-O-Si or Si-CH ₃ chemical bond is formed at the interface between the polymer substrate and the inorganic thin film layer by irradiation of radiation. Due to the chemical covalent bond, the bonding force between the polymer substrate and the inorganic thin film layer can be increased.

That is, the irradiation with the radiation can improve the binding property between the polymer substrate and the inorganic thin film layer, reduce the peeling phenomenon and the heat shrinkage rate, and can produce a polymer composite excellent in heat resistance.

In addition, as the radiation dose is increased, the heat shrinkage ratio of the polymer composite decreases, thereby improving the thermal stability of the polymer composite. Excess radiation, however, can damage the thermal stability of the composite by destroying the polymer chains of the polymer film.

Hereinafter, an electrochemical device using a polymer composite according to an embodiment of the present invention as a separator will be described.

The polymer composite according to an embodiment of the present invention can be used as a separator for an electrochemical device, and an electrochemical device includes an electrode, specifically, a separator disposed between an anode and a cathode.

The electrochemical device may be manufactured by a conventional method known in the art, and may be manufactured by assembling the positive electrode and the negative electrode with the separator of the present invention interposed therebetween, and then injecting an electrolyte solution.

The electrode is not particularly limited, and can be produced by applying an electrode active material slurry to a current collector according to a conventional method known in the art.

As the cathode active material, lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium iron oxide, or a lithium composite oxide in combination thereof may be used, but the present invention is not limited thereto.

The negative electrode active material may be lithium metal or a lithium alloy, carbon, petroleum coke, activated carbon, graphite, other carbon materials, or a lithium adsorbing material in combination thereof. Do not.

The anode current collector may be a foil made of aluminum, nickel or a combination thereof, and a cathode current collector may be a foil made of copper, gold, nickel, or a copper alloy or a combination thereof But is not limited thereto.

Wherein A + is an alkali metal cation such as Li +, Na +, K +, or an ion consisting of a combination thereof, and B- is an ion selected from the group consisting of 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) 3 - and such an anion or A salt containing an ion comprising a combination of these is selected from the group consisting of propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, The reaction is carried out in the presence of a base such as dimethlyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, n-methyl-2-pyrrolidone ), Ethylmethyl carbonate, gamma-butyrolactone, or a mixture thereof But it can be used to the dissolved or dissociated in an organic solvent consisting of, but not limited thereto.

The polymer composite according to an embodiment of the present invention may be used as the separator, and the polymer composite is the same as that of FIG. 1, so that the description of the overlapping components will be omitted.

If the polymer composite according to the embodiment of the present invention is used as a separator, the high-rate charge-discharge characteristics of the electrochemical device can be improved.

The electrolyte solution can be injected at an appropriate stage in the process depending on the manufacturing process and required properties of the electrochemical device, and specifically, before the assembly of the battery or at the final stage of assembly.

In addition to the winding process, the electrochemical device may also be fabricated by lamination and stacking processes of a separator and electrodes, and a folding process.

The electrochemical device is not particularly limited, but may be used for all kinds of capacitors such as a primary cell, a secondary cell, a fuel cell, a solar cell, or a super capacitor device.

In particular, the secondary battery may include a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, and a lithium ion polymer secondary battery.

Production Example of Polymer Complex

[Comparative Example 1]

A polyethylene polymer was melt-extruded to prepare a flow-molded separator. The polymer substrate was stretched through crystallization heat treatment to prepare a polymer base material having a thickness of about 16 탆 and a thickness of about 1 탆. The polymer substrate (porosity of 47.9%) was treated for 3 minutes under 20W oxygen plasma. (SiCl ₄ ) as a silicon precursor in a reaction chamber at 80 ° C. for 4 minutes to cooperate with moisture in the air to coat both surfaces of the porous substrate with an inorganic oxide SiO ₂ film. At this time, the inorganic thin film layer can be coated not only on the surface of the base material but also on the polymer surface forming the internal pores. The thickness of the inorganic thin film layer was formed to be 1 탆 or less, whereby a polymer composite having a total thickness of 16 탆 to 17 탆 was produced.

[Example 1]

A polyethylene polymer was melt-extruded to prepare a flow-molded separator. The polymer substrate was stretched through crystallization heat treatment to prepare a polymer base material having a thickness of about 16 탆 and a thickness of about 1 탆. The polymer substrate (porosity of 47.9%) was treated for 3 minutes under 20W oxygen plasma. The silicon tetrachloride (SiCl ₄₎ a silicon precursor in increased wear in the chamber (chamber) of 80 ℃ was coated with the SiO ₂ film of the inorganic oxide by the vapor deposition process on both sides of the polymer substrate. At this time, the inorganic thin film layer can be coated not only on the surface of the base material but also on the polymer surface forming the internal pores. The thickness of the inorganic thin film layer was formed to be 1 탆 or less, whereby a polymer composite having a total thickness of 16 탆 to 17 탆 was produced. The electron beam (e-beam) was irradiated at 5 kGy. At this time, the beam energy was 1.14 MeV, the beam current was 6.7 mA, and the irradiation speed was 10 m / min. Thereby producing a polymer composite having a total thickness of 16 탆 to 17 탆.

[Example 2]

A polymer composite was prepared in the same manner as in [Example 1], except that the polymer composite prepared in [Example 1] was irradiated with 10 kGy electron beam (e-beam).

[Example 3]

A polymer composite was prepared in the same manner as in [Example 1], except that the polymer composite prepared in [Example 1] was irradiated with 20 kGy electron beam (e-beam).

[Example 4]

A polymer composite was prepared in the same manner as in [Example 1], except that the polymer composite prepared in [Example 1] was irradiated with an electron beam (e-beam) at 30 kGy irradiation.

Manufacture of lithium secondary battery

A slurry was prepared by adding 90% by weight of LiCoO ₂ , 6% by weight of carbon black and 4% by weight of polyvinylidene fluoride (PVdF) to N-methyl-2-pyrrolidone (NMP). The slurry was coated on an aluminum thin film having a thickness of 20 탆, dried, and then rolled to produce a positive electrode.

94% by weight of graphitized mesocarbon microbeads (MCMB) and 6% by weight of polyvinylidene fluoride (PVdF) were added to N-methyl-2-pyrrolidone (NMP) to prepare a slurry. The slurry was applied to a copper foil having a thickness of 10 탆, dried, and then rolled to produce a negative electrode.

(EC), ethylmethyl carbonate (EMC), and diethylene carbonate (DEC) were mixed in a ratio of 1: 1: 1 by weight, and the positive electrode, the negative electrode and the prepared polymer composite (separator) 1, LiPF ₆ was dissolved in a mixed solvent to prepare a lithium secondary battery.

Hereinafter, the characteristics of the polymer composite according to the embodiment of the present invention will be described.

evaluation

Evaluation 1: Adhesion analysis of polymer complex

Table 1 is a table showing the adhesive strength of the inorganic thin film layer (SiO ₂ ) of the polymer composite according to the embodiment of the present invention.

Referring to Table 1, it can be seen that the adhesion value of the polymer composite (Examples 1 to 4) according to the embodiment of the present invention formed by irradiating the electron beam with respect to the polymer composite of Comparative Example 1 is increased.

In addition, in the polymer composite according to the embodiment of the present invention, the binding strength between the molecules of the polymer chain of the polymer film and the inorganic thin film layer (SiO ₂ ) is improved as the dose of electron beam is increased.

Comparative Example 1 Example 1 Example 2 Example 3 Example 4 Adhesion (tensile strength) 10 N / mm 12 N / mm 15 N / mm 20 N / mm 24 N / mm

Evaluation 2: Scanning electron microscope (SEM) analysis of polymer complex

4A to 4D are images showing a scanning electron microscope (SEM) of the surface of a polymer composite according to an embodiment of the present invention.

5 is an image showing a scanning electron microscope (SEM) of the surface of the polymer composite according to Comparative Example 1. Fig.

Referring to FIGS. 4A to 4D and FIG. 5, it can be seen that the surface of the polymer composite according to Examples 1 to 4 of the present invention is uniformly coated with the inorganic thin film layer (SiO ₂ ) It can be seen that the surface properties of the polymer composite do not change significantly.

Evaluation 3: Thermal Shrinkage Analysis of Polymer Complex

6 is an image showing the heat shrinkage rate behavior of the polymer composite according to the embodiment of the present invention.

Referring to FIG. 6, the polymer composite of Examples 1 to 4 and Comparative Example 1 was examined for the heat shrinkage rate behavior when it was stored at 140 ° C for 0.5 hours. Further, when the polymer composite was stored at 150 ° C for 0.5 hours, The behavior was confirmed.

It can be seen that Examples 1 to 4 and Comparative Example 1 show a large difference in the heat shrinkage rate behavior. The polymer composite of Comparative Example 1 exhibited insufficient heat shrinkage to an undetectable form, whereas the polymer composite of Examples 1 to 4 exhibited relatively poor heat shrinkage behavior. Particularly, in the case of Example 4, it can be confirmed that there is almost no heat shrinkage behavior. This means that the bonding strength between the inorganic thin film layer (SiO ₂ ) and the polymer substrate is enhanced by the electron beam, and the thermal characteristic is greatly improved.

Evaluation 4: Evaluation of transmittance and adhesion of polymer composite

FIG. 7 is a graph showing Fourier transform infrared spectroscopy (FT-IR) absorption behavior of a polymer composite according to an embodiment of the present invention.

Referring to FIG. 7, it can be confirmed that the polymer composite according to Examples 1 to 4 of the present invention has Si-OC, Si-O-Si or Si-CH ₃ bonds increased as compared with Comparative Example 1 . That is, it can be confirmed that the adhesion between the polymer substrate and the inorganic thin film layer is increased.

In addition, as the irradiation dose is increased, the binding property between the inorganic thin film and the polymer film is improved, and the thermal characteristics of the polymer composite are improved.

Evaluation 5: High-rate charge / discharge characteristics of lithium secondary battery

8 is a graph showing charge / discharge characteristics of a lithium secondary battery including a polymer composite (separator) according to an embodiment of the present invention.

After the lithium secondary battery was charged from 0.2C to 4.3V, it was discharged at 3.0V at 0.2C, 0.5C, 1C, 1.5C, 2C and 3C, respectively, and the charge was cut off at 20% of the initial constant current.

Referring to FIG. 8, it can be seen that the separators of Examples 1 to 4 according to the embodiment of the present invention had a higher rate of charge / discharge characteristics than the separator of Comparative Example 1.

Particularly, it can be confirmed that the most excellent charge-discharge characteristics are shown in Examples 3 and 4. This is because the electron beam irradiation causes the SiO ₂ inorganic thin film to be more uniformly placed on the surface of the porous polymer film, thereby facilitating the contact with the liquid electrolyte, thereby greatly improving the performance of the secondary battery.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. This is possible.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the equivalents of the claims, as well as the claims.

110: polymer substrate 120: inorganic thin film layer
T1: thickness of the polymer substrate T2: thickness of the inorganic thin film layer

Claims (11)

Oxygen plasma treatment of the porous polymeric substrate;
Depositing an inorganic thin film layer on at least one side of the oxygen plasma treated porous polymer substrate; And
Irradiating the inorganic thin film layer with radiation to increase the adhesive force between the polymer substrate and the inorganic thin film layer;
Lt; / RTI >
Wherein the radiation has an irradiation dose of 1 kGy to 100 kGy.
The method according to claim 1,
Wherein the radiation is electron beam (e-beam), gamma-rays, or x-ray.
delete The method according to claim 1,
The inorganic thin film layer may be formed of SiO ₂ or Al ₂ O ₃ .
The method according to claim 1,
The inorganic thin film layer may be formed of a material selected from the group consisting of WO ₃ , MnO ₂ , Fe ₂ O ₃ , Fe ₃ O ₄ , BaTiO ₃ , Pb (Zr, Ti) O ₃ (PZT), HfO ₂ , SrTiO ₃ , CeO ₂ , MgO, , ZrO ₂ , Y ₂ O ₃ , and TiO ₂ .
The method according to claim 1,
In the step of depositing the inorganic thin film layer,
The inorganic thin film layer may be formed by at least one of chemical vapor deposition (CVD), atomic layer deposition (ALD), chemical solution deposition (CBD), and thermal evaporation deposition Wherein the polymer matrix is formed by using the polymer matrix.
The method according to claim 1,
Wherein the inorganic thin film layer has a thickness of 1 nm to 1 占 퐉.
The method according to claim 1,
The porous polymer base material may be at least one selected from the group consisting of polyethylene, polypropylene, polystyrene, polypropylene terephthalate, polyethylene terephthalate, polybutylene terephthalate, Polyacrylamide, polyester, polyacetal, polyamide, polycarbonate, polyimide, polyether ether ketone, polyether sulfone, And at least one selected from the group consisting of polyphenylene oxide, polyphenylene sulfide, polyethylene naphthalene, and polyolefine.
delete The method according to claim 1,
Wherein the porous polymer substrate has a thickness of 1 占 퐉 to 50 占 퐉.
A polymer composite for an electrochemical device produced by the method according to any one of claims 1, 2, 4 to 8, and 10.

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