KR20110010516A - Perfluorinated phosphate crosslinker for gel polymer electrolyte, gel polymer electrolyte prepared from the same and electrochemical device comprising the electolyte - Google Patents

Abstract

PURPOSE: A perfluorinated phosphate acrylate cross-linking agent for gel polymer electrolyte of a specific structure is provided to ensure electrochemical stability and thermal stability. CONSTITUTION: A perfluorinated phosphate acrylate cross-linking agent for gel polymer electrolyte is denoted by chemical formula 1. A composition for gel polymer electrolyte contains electrolyte solvent, lithium salt, and gel polymer electrolyte monomer and further contains perfluorinated phosphate acrylate cross-linking agent. The electrolyte solvent is circular carbonate, linear carbonate, lactone, ether, ester, sulfoxide, acetonitrile, lactame, ketone or halogen derivative thereof. The gel polymer electrolyte is formed by polymerizing the composition for gel polymer electrolyte. An electrochemical device contains anode, cathode and gel polymer electrolyte.

Description

PERFLUORINATED PHOSPHATE CROSSLINKER FOR GEL POLYMER ELECTROLYTE, GEL POLYMER ELECTROLYTE PREPARED FROM THE SAME AND ELECTROCHEMICAL DEVICE COMPRISING THE ELECTOLYTE

The present invention relates to a perfluorinated phosphate-based acrylate crosslinking agent for a gel polymer electrolyte and a gel polymer electrolyte prepared therefrom and an electrochemical device comprising the same. More specifically, the present invention relates to a perfluorinated phosphate acrylate crosslinking agent for a gel polymer electrolyte having excellent thermal stability and flame retardancy, and a gel polymer electrolyte prepared therefrom and an electrochemical device having improved performance.

Recently, interest in energy storage technology is increasing. As the field of application extends to the energy of mobile phones, camcorders and notebook PCs, and even electric vehicles, efforts for research and development of batteries are becoming more concrete. The electrochemical device is the field that is attracting the most attention in this respect, in particular, with the recent trend of miniaturization and light weight of electronic devices, the development of secondary batteries as a battery capable of charging and discharging small size and high capacity has been the focus of attention.

Conventionally, as electrolytes for electrochemical devices such as batteries and electric double layer capacitors using an electrochemical reaction, an electrolyte in a liquid state, particularly an ion conductive organic liquid electrolyte in which salts are dissolved in a non-aqueous organic solvent, has been mainly used.

However, the use of the electrolyte in the liquid state is not only highly likely to deteriorate the electrode material and volatilize the organic solvent, but also has problems in safety such as combustion due to an increase in the ambient temperature and the temperature of the battery itself. In particular, a lithium secondary battery has a problem in that gas is generated inside the battery due to decomposition of a carbonate organic solvent and / or side reaction between the organic solvent and the electrode during charging and discharging, thereby expanding the battery thickness, and the reaction is accelerated at high temperature storage. Thus, the amount of gas generated is further increased.

This continuously generated gas causes an increase in the internal pressure of the battery, which causes the center of the specific surface of the battery to deform such as swelling of the square battery in a specific direction, as well as a local difference in adhesion at the electrode surface of the battery. This causes the problem that the electrode reaction does not occur equally in the entire electrode surface. Therefore, the performance and safety degradation of the battery is necessarily caused.

Therefore, a polymer electrolyte is used to overcome the safety problem of the liquid electrolyte. In general, battery safety is known to improve in the order of liquid electrolyte <gel gel polymer electrolyte <solid polymer electrolyte, while battery performance is known to decrease. Due to such inferior battery performance, it is known that batteries employing a solid polymer electrolyte have not been commercialized yet.

On the other hand, the gel polymer electrolyte is excellent in the electrochemical safety as described above can not only keep the thickness of the battery constant, but also excellent contact between the electrode and the electrolyte due to the inherent adhesion of the gel phase can produce a thin film battery have.

In order to improve the conductivity of the gel polymer electrolyte, efforts have been made to improve the conductivity of the polymer electrolyte by adding a low molecular weight polyalkylene oxide or an organic solvent as a plasticizer. However, when the amount of the plasticizer is increased, the physical properties of the polymer electrolyte are greatly reduced or a stable gel cannot be formed.

In order to overcome this problem, a method for producing a crosslinked polymer electrolyte by curing with UV or electron beam radiation from a composition containing a polyalkylene glycol compound having a chemically crosslinkable functional group and a mixture of an ionic conductive liquid and an electrolyte salt [US 4,830,939, J. Electrochemm. Soc., 145, 1521 (1998).

In addition, a method of using a flame retardant additive in a non-aqueous electrolyte solvent in order to improve the thermal safety of a lithium secondary battery is known. As a flame retardant additive, a method of improving the thermal safety of a lithium secondary battery by using a phosphate compound is known (US Patent No. 5,830,600, US Patent No. 6,511,772, US Patent No. 6,746,794).

Accordingly, an object of the present invention is to provide a gel polymer electrolyte crosslinking agent capable of producing a gel polymer electrolyte having excellent ion conductivity and excellent electrochemical safety and thermal stability, and a composition for gel polymer electrolyte comprising the same, and polymerizing the same. It is to provide an electrochemical device comprising the gel polymer electrolyte and the gel polymer electrolyte formed.

In addition, another object of the present invention is to include a crosslinking agent for a gel polymer electrolyte and a composition for gel polymer electrolyte comprising the same, and a gel polymer electrolyte formed by polymerizing the same, which can improve the flame retardancy of the gel polymer electrolyte. It is to provide an electrochemical device.

In order to solve the above problems, the present invention provides a perfluorinated phosphate-based acrylate crosslinking agent for a gel polymer electrolyte represented by the following formula (1):

In Formula 1, n is an integer of 1 or 2.

The crosslinking agent of the present invention is the carbon in the carbon chain is bonded to the fluorine, the C-F bond is greater than the C-H bond is determined that the durability of the polymer is believed to contribute to improved safety. In addition, fluorine is thought to contribute greatly to improving the flame retardancy of polymers.

In addition, the crosslinking agent of the present invention may form a gel polymer electrolyte composition together with a conventionally used electrolyte solvent, lithium salt and gel polymer electrolyte monomer. The content of the crosslinking agent of the present invention may be appropriately adjusted as necessary, and may be, for example, 0.1 to 30 parts by weight based on 100 parts by weight of the composition for gel polymer electrolyte, but is not limited thereto.

In addition, the gel polymer electrolyte of the present invention is formed by polymerizing the composition for gel polymer electrolyte.

In addition, the electrochemical device of the present invention includes a positive electrode, a negative electrode and the gel polymer electrolyte.

Gel polymer electrolytes made from the perfluorinated phosphate-based acrylate crosslinkers of the present invention may have excellent ionic conductivity.

In addition, the gel polymer electrolyte prepared from the perfluorinated phosphate-based acrylate crosslinking agent of the present invention has improved electrochemical stability and flame retardancy due to fluorine in the crosslinking agent.

Hereinafter, the present invention will be described in detail. The terms or words used in this specification and claims are not to be construed as being limited to the common or dictionary meanings, and the inventors may appropriately define the concept of terms in order to best explain their invention in the best way possible. It should be interpreted as meaning and concept corresponding to the technical idea of the present invention based on the principle that the present invention.

The perfluorinated phosphate-based acrylate crosslinking agent for the gel polymer electrolyte of the present invention is represented by the following Chemical Formula 1:

[Formula 1]

In Formula 1, n is an integer of 1 or 2.

Schematic representation of the reaction scheme for preparing the crosslinking agent of the present invention can be represented by the following scheme 1:

In Scheme 1, n is an integer of 1 or 2.

As shown in Scheme 1, hydroxy fluorinated tri (tetra) ethylene glycol monoacrylate represented by the formula (2) is a phosphorus oxytree represented by the formula (3) The crosslinking agent of the present invention represented by Chemical Formula 1 may be obtained by reacting with chloride (phosphorous oxychloride). At this time, the reaction conditions for obtaining the hydroxy fluorinated tri (tetra) ethylene glycol monoacrylate of the formula (2) can be used without limitation the conditions commonly performed in the art, for example about 4 ℃ at about 4 ℃ May be performed for ˜5 hours. In addition, reaction conditions for obtaining the crosslinking agent of Chemical Formula 1 may also be performed under a nitrogen atmosphere, for example, at about 50 ° C. for about 12 hours, but is not limited thereto.

Phosphate-based compounds are commonly known to be useful as flame retardants. The crosslinking agent of the present invention not only contains a phosphate moiety but also has fluorine bonded to all carbon atoms, thereby further improving flame retardancy. In addition, C-F bonds have a very high bonding force, so the stability of the structure itself is very high. Therefore, the crosslinking agent of the present invention is useful for preparing an electrolyte having improved electrochemical stability and thermal stability and particularly flame retardancy of the electrolyte, and thus can be suitably used for electrolytes of lithium secondary batteries that may be subject to ignition or explosion.

Therefore, the present invention provides a gel polymer electrolyte composition comprising an electrolyte solvent, a lithium salt, and a gel polymer electrolyte monomer, wherein the gel polymer electrolyte composition further comprises a perfluorinated phosphate-based acrylate crosslinking agent represented by Formula 1 above. to provide. The content of the perfluorinated phosphate acrylate crosslinking agent may be 0.1 to 30 parts by weight based on 100 parts by weight of the composition for gel polymer electrolyte, but is not limited thereto. If the content is less than 0.1 part by weight, the effect as a crosslinking agent is insufficient and the mechanical properties of the electrolyte are lowered. If the content is more than 30 parts by weight, the ionic conductivity of the electrolyte may be reduced.

In the gel polymer electrolyte composition of the present invention, the electrolyte solvent may be used without limitation, the electrolyte solvent commonly used in the art, for example, cyclic carbonate, linear carbonate, lactone, ether, ester, sulfoxide, aceto Nitriles, lactams, ketones and halogen derivatives thereof may be used alone or in combination of two or more thereof.

Examples of the cyclic carbonate include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), fluoroethylene carbonate (FEC), and the like. Examples of the linear carbonate include diethyl carbonate (DEC) and dimethyl carbonate. (DMC), dipropyl carbonate (DPC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC), and the like. Examples of the lactone include gamma butyrolactone (GBL), and examples of the ether include dibutyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, 1,2-diethoxyethane and the like. Examples of such esters include methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, butyl propionate, methyl pivalate and the like. The sulfoxide includes dimethyl sulfoxide, the lactam includes N-methyl-2-pyrrolidone (NMP), and the ketone includes polymethylvinyl ketone. In addition, these halogen derivatives can also be used, and are not limited only to the electrolyte solution illustrated above. In addition, these electrolyte solution solvents can be used individually or in mixture of 2 or more types, respectively.

The content of the electrolyte solvent may be 0.1 to 98 parts by weight based on 100 parts by weight of the composition for gel polymer electrolyte, but is not limited thereto. If the content is less than 0.1 parts by weight, the ionic conductivity of the electrolyte may be lowered. If the content is more than 98 parts by weight, the mechanical properties of the electrolyte may be reduced, making it difficult to manufacture a thin film.

In the gel polymer electrolyte composition of the present invention, lithium salts can also be used without limitation lithium salts commonly used in the art, for example, LiClO ₄ , LiCF ₃ SO ₃ , LiBFS ₄ , LiPF ₆ , LiAsF ₆ and Li (CF ₃ SO ₂ ) ₂ N and the like can be used.

The content of the lithium salt may be 3 to 40 parts by weight based on 100 parts by weight of the gel polymer electrolyte composition, but is not limited thereto. If the content is less than 3 parts by weight, the concentration of lithium ions is too low to function as an electrolyte. If the content is more than 40 parts by weight, solubility problems of lithium salts and ionic conductivity of the electrolyte may be reduced.

The polymer electrolyte monomer used in the present invention is not particularly limited as long as it is a compound in which a polymerization reaction can occur, and preferably a polymerizable functional group selected from the group consisting of vinyl group, epoxy group, allyl group, and (meth) acryl group. It may be a compound having. In addition, when there are two or more polymerizable functional groups in the polymer electrolyte monomer, the polymerizable functional groups may be the same or different from each other.

Non-limiting examples of the polymer electrolyte monomer include tetraethylene glycol diacrylate, polyethylene glycol diacrylate (molecular weight 50-20,000), 1,4-butanediol diacrylate (1 , 4-butanediol diacrylate, 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, trimethylolpropane ethoxylate triacrylate , Trimethylolpropane propoxylate triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol tetraacrylate, pentaerythritol ethoxylate tetraacrylate pentaerythritol ethoxylate tetraacrylate), diphene Erythritol pentaacrylate, dipentaerythritol hexaacrylate, polyethylene glycol diglycidyl ether, 1,5-hexadiene diepoxide (1 , 5-hexadiene diepoxide, glycerol propoxylate triglycidyl ether, vinylcyclohexene dioxide, 1,2,7,8-diepoxyoctane (1,2,7,8 diepoxyoctane, 4-vinylcyclohexene dioxide, butyl glycidyl ether, diglycidyl 1,2-cyclohexanedicarboxylate, Ethylene glycol diglycidyl ether, glycerol triglycidyl ether, glycidyl methacrylate, and the like, but are not limited thereto. Does, these monomers can be used individually or in combination of two or more.

The polymer electrolyte monomer may be included in an amount of 0.5 to 10 parts by weight based on 100 parts by weight of the composition for gel polymer electrolyte. If it is less than 0.5 parts by weight, the gel polymer is difficult to form, and if it is more than 10 parts by weight, the gel polymer is not only formed, but the content of the electrolyte solvent in the electrolyte is low, thereby reducing the ion conductivity of the battery and causing the performance of the battery. can do.

The composition for gel polymer electrolyte of the present invention may include conventional polymerization initiators known in the art. The polymerization initiator according to the present invention decomposes by heat to form radicals, and reacts with monomers by free radical polymerization to form a gel polymer electrolyte.

Non-limiting examples of the polymerization initiator are benzoyl peroxide, acetyl peroxide, dilauryl peroxide, di-tert-butyl peroxide, organic peroxides and hydroperoxides such as t-butyl peroxy-2-ethyl-hexanoate, cumyl hydroperoxide and hydrogen peroxide; 2,2'-azobis (2-cyanobutane) (2,2'-azobis (2-cyanobutane)), 2,2'-azobis (methylbutyronitrile) (2,2'-azobis (methylbutyronitrile) ), Azo compounds such as AIBN (2,2'-azobis (iso-butyronitrile)) and AMVN (2,2'-azobisdimethyl-valeronitrile).

The polymerization initiator may be included in an amount of 0.01 to 20 parts by weight based on 100 parts by weight of the composition for gel polymer electrolyte.

The composition for gel polymer electrolyte according to the present invention may optionally contain, in addition to the components described above, other additives known in the art within the scope of the present invention.

The gel polymer electrolyte of the present invention is formed by polymerizing the above-described composition for gel polymer electrolyte of the present invention according to conventional methods known in the art. More specifically, the composition for gel polymer electrolyte of the present invention is sufficiently mixed with a suitable thickness on a support such as a glass plate, polyethylene-based vinyl or commercial Mylar film or a battery electrode, and then irradiated with an electron beam or an ultraviolet gamma ray. Alternatively, the gel polymer electrolyte may be obtained by inducing a curing reaction under heating conditions, but the present invention is not limited thereto.

In addition, the electrochemical device of the present invention may be prepared including a positive electrode, a negative electrode, a separator and a gel polymer electrolyte formed by polymerizing the composition for gel polymer electrolyte according to the present invention.

The electrochemical device includes all devices that undergo an electrochemical reaction, and specific examples thereof include all kinds of primary, secondary batteries, fuel cells, or capacitors, and particularly, lithium secondary batteries are preferable.

In addition, the electrode of the electrochemical device can be prepared by conventional methods known in the art. For example, a slurry may be prepared by mixing and stirring a solvent, a binder, a conductive material, and a dispersant in an electrode active material, and then applying (coating) to a current collector of a metal material, compressing, and drying the electrode to prepare an electrode. have.

The electrode active material may be a positive electrode active material or a negative electrode active material.

The positive electrode active material may be _a lithium transition metal composite oxide such as LiM _x O _y (M = Co, Ni, Mn, Co _a Ni _b Mn _c ) (for example, lithium manganese composite oxide such as LiMn ₂ O ₄ , LiNiO _2, etc.). Lithium cobalt oxides such as lithium nickel oxide, LiCoO ₂ , and manganese, nickel, and cobalt in which some of these oxides are substituted with other transition metals, or lithium-containing vanadium oxide, or a chalcogenide compound (for example, manganese dioxide) , Titanium disulfide, molybdenum disulfide, etc.) may be used, but is not limited thereto.

The negative electrode active material may be a conventional negative electrode active material that can be used for the negative electrode of the conventional electrochemical device, non-limiting examples thereof lithium metal, lithium alloy, carbon, petroleum coke that can occlude and release lithium ions ), Activated carbon, graphite, carbon fiber, and the like. In addition, lithium oxide may be occluded and released, and metal oxides such as TiO ₂ , SnO _2, and the like having a potential of less than ₂ V may be used, but are not limited thereto. In particular, carbon materials such as graphite, carbon fiber and activated carbon are preferable.

The current collector of the metal material is a metal having high conductivity and which the slurry of the electrode active material can easily adhere to, and may be used as long as it is not reactive in the voltage range of the battery. Non-limiting examples of the positive electrode current collector is a foil produced by aluminum, nickel or a combination thereof, and non-limiting examples of the negative electrode current collector is produced by copper, gold, nickel or copper alloy or a combination thereof Foil and the like.

The separator is not particularly limited, but it is preferable to use a porous separator, and non-limiting examples include a polypropylene-based, polyethylene-based, or polyolefin-based porous separator. In addition, as a method of applying the separator to a battery, in addition to the general winding method, the separator and the electrode may be laminated, folded, and the like.

The electrochemical device of the present invention is not limited in appearance, but may be cylindrical, square, pouch or coin type using a can.

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

Preparation Example 1 Synthesis of Hydroxy Fluorinated Triethylene Glycol Monoacrylate

Triethylamine dissolved in THF (50 g) was dissolved in THF (150 ml) after dissolving fluorinated triethylene glycol (50 g, 0.170 mol), the starting material described in Scheme 1, in a three-necked flask. (35.544 ml, 0.255 mol) is slowly added dropwise and stirred for 30 minutes. Then, acryloyl chloride (17.953 ml, 0.221 mol) dissolved in THF (50 g) was slowly added dropwise and the reaction proceeded for 4-5 hours.

The precipitate obtained as a result of the reaction was filtered and extracted with dichloromethane. The organic layer was dried over MgSO ₄ , then separated by column chromatography (dichloromethane / hexane = 1/1, dichloromethane), and 28 g of hydroxy fluorinated triethylene glycol monoacrylate represented by Chemical Formula 2 in Scheme 1 (yield) 47%). ¹ H-NMR analysis of the prepared hydroxy fluorinated triethylene glycol monoacrylate is as follows:

¹ H-NMR (300 MHz, CDCl ₃ ): δ 6.55-6.50 (d, J = 17.7 Hz, 1H), 6.23-6.14 (q, 1H), 6.01-5.97 (d, J = 10.5 Hz, 1H), 4.60-4.55 (t, 2H), 3.95-3.89 (q, 2H), 2.94 (s, 1H).

Preparation Example 2 Synthesis of Hydroxy Fluorinated Tetraethylene Glycol Monoacrylate

The reaction was carried out in the same manner as in Preparation Example 1, except that fluorinated tetraethylene glycol (50 g) was used instead of fluorinated triethylene glycol, and 25.509 ml of triethylamine and 12.882 ml of acryloyl chloride were used. 25 g (yield 47%) of hydroxy fluorinated tetraethylene glycol monoacrylate represented by Chemical Formula 2 in Scheme 1 was obtained. ¹ H-NMR analysis of the prepared hydroxy fluorinated tetraethylene glycol monoacrylate is as follows:

¹ H-NMR (300 MHz, CDCl ₃ ): δ 6.65-6.50 (d, J = 18 Hz, 1H), 6.22-6.13 (q, 1H), 6.01-5.98 (d, J = 10.5 Hz, 1H), 4.60-4.54 (t, 2H), 3.99-3.91 (q, 2H), 2.73-2.68 (t, 1H).

Example 1 Synthesis of Perfluorinated Phosphate Acrylate Crosslinker (n = 1)

The hydroxy fluorinated triethylene glycol monoacrylate (20 g, 0.057 mol) prepared in Preparation Example 1 was dissolved in dichloromethane (50 ml) in a three-necked flask, and then triethylamine (10.453 ml, 0.075 mol) was stirred. ) Was slowly added dropwise and stirred for 1 hour. Phosphorus oxychloride (1.739 ml, 0.019 mol) purified with sodium was slowly added dropwise thereto, refluxed at 50 ° C. for 12 hours under a nitrogen atmosphere, and then cooled.

The precipitate obtained as a result of the reaction was filtered and then extracted with ethyl acetate. The organic layer was dried with MgSO _4, and then separated by column chromatography (dichloromethane / hexane = 1/1, dichloromethane) to obtain 13 g of a perfluorinated phosphate acrylate crosslinking agent (n = 1) represented by Chemical Formula 1 (yield 62). %) Was obtained. Results of ¹ H-NMR analysis of the prepared crosslinker are as follows:

¹ H-NMR (300 MHz, CDCl ₃ ): δ 6.54-6.48 (d, J = 18.39 Hz, 3H), 6.22-6.13 (q, 3H), 5.98-5.94 (d, J = 10.47 Hz, 3H), 4.59-4.51 (t, 6H), 4.46-4.37 (q, 6H).

Example 2 Synthesis of Perfluorinated Phosphate-Based Acrylate Crosslinker (n = 2)

Instead of hydroxy fluorinated triethylene glycol monoacrylate, 20 g of hydroxy fluorinated tetraethylene glycol monoarcate obtained in Preparation Example 2 was used, and 7.792 g of triethylamine and 1.309 g of phosphorus oxychloride were used. The reaction was carried out in the same manner as in Example 1 except that 12 g of a perfluorinated phosphate acrylate crosslinking agent (n = 2) represented by Formula 1 was obtained (58% yield). Results of ¹ H-NMR analysis of the prepared crosslinker are as follows:

¹ H-NMR (300 MHz, CDCl ₃ ): δ 6.65-6.48 (d, J = 17.4 Hz, 3H), 6.21-6.12 (q, 3H), 5.98-5.95 (d, J = 10.5 Hz, 3H), 4.59-4.52 (t, 6H), 4.46-4.37 (q, 6H).

Experimental Example 1. Evaluation of ion conductivity

Electrolytic thin film manufacturing

To prepare a composition for a gel polymer electrolyte with the composition shown in Table 1, and then injected into a cell formed between the conductive glass (ITO) substrate and the transparent glass substrate via a spacer, and heated for 20 to 30 minutes at 80 ℃ under argon stream To prepare a gel polymer electrolyte thin film.

However, a solvent in which ethylene carbonate (EC), propylene carbonate (PC) and diethyl carbonate (DEC) are mixed at 2: 2: 4, or ethylene carbonate (EC) and propylene carbonate (PC) is 1: 1 as an electrolyte solution solvent. using the mixed solvent and the LiPF ₆ here such that LiPF ₆ was added to a concentration of 1M.

In addition, trimethylolpropane triacrylate (A3) was used as the polymer electrolyte monomer, and benzoyl peroxide was used as the polymerization initiator.

<Ion Conductivity Measurement>

Ionic conductivity is injected into a gel-type polymer electrolyte composition prepared in the composition shown in Table 1 to a band-shaped conductive glass substrate or lithium-copper foil, and then thermally cured to polymerize, dried sufficiently, and then band-shaped or AC impedance of the sandwich electrode was measured, and the measured value was analyzed by a frequency response analyzer to obtain a method of analyzing the complex impedance, and the results are shown in Table 1 below.

The band-shaped electrode was attached to the conductive glass (ITO) at a width of about 1mm and attached to the conductive glass (ITO) at an interval of 2 cm, and then etched, washed, and dried to prepare a cell.

Crosslinking agent (g) Monomer (A3) (g) Electrolyte Solvent (g)
(1M LiPF ₆ ) Initiator (g) Ion Conductivity (S / cm)
δ x 10 ^-2 Example 1 0.08 0.02 EC / PC 1.9 0.02 0.622 EC / PC / DEC 1.035 EC / PC 3.23 0.818 EC / PC / DEC 1.177 Example 2 0.08 0.02 EC / PC 1.9 0.02 0.761 EC / PC / DEC 0.895 EC / PC 3.23 1.024 EC / PC / DEC 1.16

Experimental Example 2 Evaluation of Electrochemical Safety

A crosslinking agent prepared according to Example 1 on a 1 cm x 1 cm nickel electrode, A3 as a monomer, ethylene carbonate (EC), propylene carbonate (PC) and diethyl carbonate (DEC) as an electrolyte were mixed in a 2: 2: 4 mixture. A gel polymer electrolyte thin film was prepared by the same method as described in Experimental Example 1, using a solution prepared by using 1 M LiPF ₆ in the prepared solvent (95 wt%, 97 wt%, 98 wt% of the electrolyte), and lithium The electrode was covered and then vacuum packed to prepare a cell for measuring electrochemical stability.

Electrochemical stability was measured at a rate of 10 mV / sec to -0.5 ~ 5 V using a linear scanning potential method, the results are shown in FIG.

As shown in FIG. 1, a reversible oxidation / reduction of lithium was observed between −0.5 and 5 V, and there was almost no current at which electrolyte decomposed below 4.5V. From this, it can be seen that the gel polymer electrolyte according to the present invention has sufficient electrochemical stability as an electrolyte of a lithium secondary battery because the gel polymer electrolyte is electrochemically stable up to 4.5V at a lithium reference electrode even when the content of the electrolyte solvent is high.

Experimental Example 3. Evaluation of Battery Characteristics

A cross-linking agent prepared according to Example 2 on the positive electrode (LiCoO ₂ ) of 2cm X 2cm, A3 as a monomer, and a solvent mixed with EC: PC: DEC = 2: 2: 4 as an electrolyte (97% of electrolyte) Weight%) to prepare a gel polymer electrolyte thin film in the same manner as in Experimental Example 1 using a solution made of 1M LiPF ₆ , sandwiched between the negative electrode (carbon), and vacuum-packed to prepare a test cell.

After charging the manufactured lithium secondary battery at 0.5C until the voltage reached 4.2V, the battery was charged and discharged 17 times at 0.5C until the voltage reached 2.8V, and the capacity retention ratio was measured. The results are shown in Table 2 below.

The capacity retention rate after the 17th charge / discharge is the ratio of the discharge capacity at the 17th cycle to the discharge capacity at the 1st cycle.

Cycles 1 time 10th Episode 17 Capacity (mAh) 10.30 9.946 9.76 Capacity retention 100% 96% 95%

According to Table 2, the capacity retention rate of the secondary battery using the electrolyte membrane prepared by the crosslinking agent according to the present invention is excellent, it can be confirmed that the gel polymer electrolyte according to the present invention is suitable for use in the battery.

Experimental Example 4. Evaluation of Battery Characteristics

Example 4

A crosslinking agent prepared according to Example 2, A3 was used as a monomer, and 1M LiPF ₆ was used as a solvent (97% by weight of electrolyte) mixed with EC: PC: DEC = 2: 2: 4 as an electrolyte. To prepare a gel polymer electrolyte thin film in the same manner as in Experimental Example 1, to produce a coin-type negative electrode half cell (anode coin half cell).

The prepared battery was discharged at 0.2C, cut-off after 50 minutes, and charged and discharged at 0.2C for 2 cycles. Thereafter, the discharged battery was opened in a glove box in an argon atmosphere, the negative electrode was extracted, inserted into a DSC sample pan, and sealed.

Differential Scanning Calorimetry (Q 100, TA) measured the temperature increase rate was 5 ℃ / min, the temperature range was 30 ~ 170 ℃. The measurement result is shown in FIG.

Comparative Example 1

A battery was prepared in the same manner as in Example 4 except that the electrolyte was prepared without using a crosslinking agent and a monomer, and DSC measurement was performed. The results are shown in FIG. 2.

Comparative Example 2

Except for using a crosslinking agent (n = 1) represented by the following formula (A) as a crosslinking agent, a battery was prepared in the same manner as in Example 4 and DSC measurements were performed, and the results are shown in FIG. 2.

[Formula A]

In formula (A), R ₁ and R ₂ are each a hydrogen atom or a methyl group.

The following drawings, which are attached to this specification, illustrate preferred embodiments of the present invention, and together with the contents of the present invention serve to further understand the technical spirit of the present invention, the present invention is limited to the matters described in such drawings. It should not be construed as limited.

1 is a graph showing the results of electrochemical stability measured in Experimental Example 2 of the present invention.

2 is a graph showing the results of DSC measurement performed in Experimental Example 4 of the present invention.

Claims (9)

A perfluorinated phosphate acrylate crosslinking agent for a gel polymer electrolyte represented by Formula 1 below: [Formula 1]

In Formula 1, n is an integer of 1 or 2. In a composition for gel polymer electrolyte comprising an electrolyte solvent, a lithium salt and a gel polymer electrolyte monomer, A composition for a gel polymer electrolyte further comprising a perfluorinated phosphate acrylate crosslinking agent represented by Formula 1 below: [Formula 1]

In Formula 1, n is an integer of 1 or 2. The method of claim 2, The electrolyte solvent is any one selected from the group consisting of cyclic carbonate, linear carbonate, lactone, ether, ester, sulfoxide, acetonitrile, lactam, ketone and halogen derivatives thereof, or a mixture of two or more thereof. Gel polymer electrolyte composition. The method of claim 2, The lithium salt is a composition for gel polymer electrolyte, characterized in that any one selected from the group consisting of LiClO ₄ , LiCF ₃ SO ₃ , LiBFS ₄ , LiPF ₆ , LiAsF ₆ and Li (CF ₃ SO ₂ ) ₂ N. The method of claim 2, The gel polymer electrolyte monomers are tetraethylene glycol diacrylate, polyethylene glycol diacrylate (molecular weight 50-20,000), 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, trimethylolpropane triacryl Latex, trimethylol propane ethoxylate triacrylate, trimethylol propane propoxylate triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol tetraacrylate, pentaerythritol ethoxylate tetraacrylate, dipentaerytate Lithol pentaacrylate, dipentaerythritol hexaacrylate, polyethylene glycol diglycidyl ether, 1,5-hexadiene diepoxide, glycerol propoxylate triglycidyl ether, vinylcyclohexene dioxide, 1,2,7 , 8-diepoxyoctane, 4-vinylcyclohexene dioxide, butyl gly Any one or a mixture of two or more selected from the group consisting of dill ether, diglycidyl 1,2-cyclohexanedicarboxylate, ethylene glycol diglycidyl ether, glycerol triglycidyl ether, glycidyl methacrylate A composition for gel polymer electrolytes, characterized in that. The method of claim 2, The content of the perfluorinated phosphate-based acrylate crosslinking agent is a composition for a gel polymer electrolyte, characterized in that 0.1 to 30 parts by weight based on 100 parts by weight of the composition for gel polymer electrolyte. The gel polymer electrolyte formed by polymerizing the composition for gel polymer electrolytes in any one of Claims 2-6. An electrochemical device comprising an anode, a cathode and the gel polymer electrolyte of claim 7. The method of claim 8, The electrochemical device is an electrochemical device, characterized in that the lithium secondary battery.

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