KR101292835B1 - Cyclotriphophazene based cross linker and polymer electrolyte composition containing the same - Google Patents

Abstract

The present invention relates to a cyclotriphosphazene crosslinking agent for a polymer electrolyte and a solid polymer electrolyte composition containing the same, wherein the solid polymer electrolyte composition containing the cyclotriphosphazene crosslinking agent according to the present invention is ethylene of a crosslinker side chain even at a low temperature. By lowering the crystallization of the oxide unit, not only the ion conductivity is greatly improved, but also the electrochemical and thermal stability is excellent, so it is useful as a polymer electrolyte of a small lithium-polymer secondary battery, a power storage device for power leveling, and a large-capacity lithium-polymer secondary battery. Can be used.

Description

Cyclotriphosphazene crosslinking agent and polymer electrolyte composition containing same {Cyclotriphophazene based cross linker and polymer electrolyte composition containing the same}

The present invention relates to a cyclotriphosphazene crosslinking agent for a polymer electrolyte and a polymer electrolyte composition containing the same.

Since electrochemical devices using liquid electrolytes have problems of stability such as leakage and explosion potential, electrochemical devices using polymer electrolytes have been developed to solve such problems. Electrochemical devices using polymer electrolytes include, for example, lithium-polymer batteries, which are not only excellent in safety but also have high charging and discharging efficiency, which are economical, and various designs are possible. There was an advantage in that the battery can be miniaturized.

In particular, the case of using the polyalkylene oxide (PAO) -based solid polymer which is most widely used as the polymer electrolyte and the gel polymer electrolyte containing the organic liquid electrolyte in the polymer was of interest as the polymer electrolyte of the lithium secondary battery. In general, efforts have been made to improve the conductivity of a polymer electrolyte by adding a low molecular weight polyalkylene oxide or an organic solvent as a plasticizer in order to improve the conductivity of the polymer electrolyte. However, when the content of the plasticizer is increased, the physical properties of the polymer electrolyte are greatly reduced, and stable gel can not be formed.

In order to overcome this problem, U.S. Patent No. 4,830,939 includes a polyalkylene glycol compound having a chemically crosslinkable functional group and is cured by UV or electron beam radiation from a mixture of an ion conductive liquid and an electrolyte salt to form a crosslinked polymer. A method of preparing an electrolyte is disclosed.

U.S. Patent No. 5,830,600 discloses a method of using a phosphate flame retardant additive in a non-aqueous electrolyte solvent to improve the thermal safety of a lithium secondary battery.

(Fenton, JM Parker, PV Wright, Polymer, 14 (1973) 589.) has been reported since the reported ion conductivity of polyethylene oxide (PEO) solid polymer electrolytes (SPE) Recent research trends on solid polymer electrolytes have involved the use of PEO-based solid polymer electrolytes as a matrix for lithium salts. The PEO-based solid polymer electrolyte is considered as a candidate for a solid electrolyte for a secondary lithium battery with a high energy concentration. However, it is not yet used as a commercial product. One of the issues with solid polymer electrolytes is the improvement of ionic conductivity at room temperature. However, the high crystallinity of PEO-based polymers has a problem of inhibiting the movement of ions by inducing a rigid structure at room temperature.

Other treatments have been studied to reduce the crystallinity and improve the ionic conductivity of solid polymer electrolytes (K. Xu, Chem. Rev., 2004, 104, 4303). One efficient way to reduce the crystallinity of PEO is to prepare solid polymer electrolytes in the form of oligo (ethyleneoxide) side chains and grafted comb or net using other polymer backbones such as polyphosphazenes, polyacrylates and polysiloxanes. will be.

For example, rigid phosphazene ring centers and multi-branched oligo (ethylene oxide) groups enhance ionic conductivity as an effective plasticizer (HR Allcock, R. Ravikiran, SJM O'Connor, Macromolecules 30 (1997) 3184). As is known from previous studies, the ionic conductivity is significantly improved by using a star-shaped multi-branched oligo (ethylene oxide) as a plasticizer in a solid polymer electrolyte crosslinked in semi-inter penetrating networks (YIP) type (Y Kang, J. Lee, J.-I. Lee, C. Lee, J. Power Sources 165 (2007) 92; J.-I. Lee, Y. Kang, D. Kim, C. Lee, J. Power Sources 195 (2010) 6138).

Accordingly, while the present inventors are studying a method of improving the ionic conductivity by reducing the crystallinity of a solid polymer electrolyte composition containing a polyalkylene oxide compound, a solid polymer comprising a novel cyclotriphosphazene crosslinking agent and a plasticizer The present invention has been found to be excellent in ionic conductivity due to low crystallinity even at low temperatures.

An object of the present invention is to provide a novel cyclotriphosphazene crosslinking agent.

Another object of the present invention to provide a solid polymer electrolyte composition comprising the crosslinking agent.

In order to achieve the above object, the present invention provides a cyclotriphosphazene crosslinking agent represented by the following formula (1):

[Formula 1]

(In the formula 1,

이고,R ¹ is

ego,

n is an integer of 0 to 20).

In addition, the present invention provides a compound (4) by alkoxylation of the R ³ substituent on the starting material hexachlorocyclotriphosphazene as shown in Scheme 1 (step 1);

Preparing compound 5 by treating compound 4 obtained in step 1 with pyridinium p-toluenesulfonate (step 2); And

Compound 5 obtained in step 2 is reacted with triethylamine and methacryloyl chloride to provide compound 1 (step 3) to provide a method for preparing the cyclotriphosphazene crosslinking agent:

[Reaction Scheme 1]

(In the above Reaction Scheme 1,

이고,R ³ is

ego,

y is an integer from 0 to 20,

이고,R ⁴ is

ego,

z is an integer from 0 to 20,

R ¹ is as defined in Formula 1).

Furthermore, the present invention is 0.1 to 95% by weight of the cyclotriphosphazene crosslinking agent represented by the formula (1);

0.1 to 96.8% by weight of at least one plasticizer selected from a plasticizer and a non-aqueous polar solvent represented by Formula 2 below;

3-40% by weight of lithium salt; And

It provides a solid polymer electrolyte composition comprising 0.1 to 5% by weight of a curable initiator:

[Formula 2]

(In the formula (2)

이고,R ² is

ego,

m is an integer of 0-9).

The present invention also provides a solid polymer electrolyte thin film coated with the solid polymer electrolyte composition.

Furthermore, the present invention provides a lithium-polymer secondary battery comprising the solid polymer electrolyte composition.

The solid polymer electrolyte composition containing the cyclotriphosphazene crosslinking agent according to the present invention not only greatly improves the ionic conductivity by lowering the crystallization of the ethylene oxide unit of the crosslinking agent side chain even at low temperature, but also has excellent electrochemical and thermal stability. It can be usefully used as a polymer electrolyte of a small lithium-polymer secondary battery, a power storage device for power leveling, and a large capacity lithium-polymer secondary battery.

1 is a graph showing the ionic conductivity of an electrolyte according to the temperature according to the length of the ethylene oxide unit of the plasticizer.
2 is a graph showing the change in ion conductivity of an electrolyte according to the lithium salt content.

Hereinafter, the present invention will be described in detail.

The present invention provides a cyclotriphosphazene crosslinking agent represented by the following formula (1).

In Formula 1,

이고,R ¹ is

ego,

n is an integer of 0-20.

The cyclotriphosphazene crosslinking agent represented by the formula (1) according to the present invention crosslinking agents in various fields, such as to improve the thermal stability of the ignition or explosion due to the use of an organic solvent or when chemical and electrochemical stability is required Can be applied as In particular, the phosphazene-based compound may be useful as a flame retardant, which may help stability of a lithium battery when applied to a gel electrolyte using a volatile organic solvent.

In addition, the present invention provides a method for preparing a cyclotriphosphazene crosslinking agent of the formula (1).

As shown in Scheme 1, a crosslinking agent of Chemical Formula 1, alkoxylating an R ³ substituent to hexachlorocyclotriphosphazene, which is a starting material, is used to prepare Compound 4 (Step 1);

Preparing compound 5 by treating compound 4 obtained in step 1 with pyridinium p-toluenesulfonate (step 2); And

Compound 5 obtained in step 2 may be prepared by a method comprising the step (step 3) of preparing compound 1 by reacting with triethylamine and methacryloyl chloride.

[Reaction Scheme 1]

In the above Reaction Scheme 1,

이고,R ³ is

ego,

y is an integer from 0 to 20,

이고,R ⁴ is

ego,

z is an integer from 0 to 20,

R ¹ is the same as defined in Chemical Formula 1.

Furthermore, the present invention provides a solid polymer electrolyte composition containing the compound of Formula 1 as a crosslinking agent.

Solid polymer electrolyte composition according to the present invention is 0.1 to 95% by weight of a cyclotriphosphazene crosslinking agent represented by the formula (1); 0.1 to 96.8% by weight of at least one plasticizer selected from a plasticizer and a non-aqueous polar solvent represented by Formula 2 below; 3-40% by weight of lithium salt; And 0.1 to 5% by weight of a curing initiator.

In Formula 2,

이고,R ² is

ego,

m is an integer of 0-9.

In the solid polymer electrolyte composition according to the present invention, the cyclotriphosphazene crosslinking agent represented by Chemical Formula 1 improves compatibility with a plasticizer introduced to improve ion conductivity of the electrolyte because a polyalkylene oxide group is introduced. Since the acrylic group is further introduced, the polymer electrolyte plays a role of forming a three-dimensional network.

At this time, the crosslinking agent is contained in the range of 0.1 to 95% by weight, preferably 1 to 80% by weight, more preferably 3 to 60% by weight in the total polymer electrolyte composition. When the content is less than 0.1% by weight, the amount is too small to obtain an effect as a crosslinking agent, and there is a problem that the mechanical properties are lowered. When the content is more than 95% by weight, the ion conductivity is reduced.

In the solid polymer electrolyte composition according to the present invention, the plasticizer represented by Chemical Formula 2 may be used alone or in admixture with a non-aqueous polar solvent, and may help to improve ion conductivity by improving lithium salt dissociation and lithium ion conductivity. To serve.

In this case, the plasticizer represented by Chemical Formula 2 may be one in which the polyethylene oxide chain extends in the form of a branch from the mother core as in the following examples:

,

,

.

,

,

.

As the non-aqueous polar solvent, at least one selected from alkylene carbonate, alkyl tetrahydrofuran, dioxirane, lactone and acetonitrile may be used. Specific examples thereof include ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxirane, 4,4-dimethyl- ? -butyrolactone, acetonitrile, and the like can be used.

Furthermore, the plasticizer may be contained in the total polymer electrolyte composition in the range of 0.1 to 96.8% by weight, preferably 0.1 to 90% by weight. In general, the amount of plasticizer included in the polymer electrolyte is directly proportional to the ion conductivity of the polymer electrolyte, but when the content is less than 0.1 wt%, the effect of improving the ion conductivity is insignificant. When the content exceeds 96.8 wt%, the mechanical properties There is a problem that can not be reduced to make a thin film is difficult to apply to battery manufacturing. Therefore, when the above range is maintained, it is possible to produce a thin film having a thickness of 100 mu m or less.

In the solid polymer electrolyte composition according to the present invention, the lithium salt is not particularly limited to those commonly used in the art for preparing a polymer electrolyte. LiClO ₄ , LiCF ₃ SO ₃ , LiBF ₄ , LiPF ₆ , LiAsF ₆ , Li (CF ₃ SO ₂ ) ₂ N and the like can be specifically used as the lithium salt generally used conventionally.

In this case, the lithium salt is contained in the range of 3 to 40% by weight, preferably 5 to 25% by weight in the total polymer electrolyte composition, the amount may be adjusted by an appropriate mixing ratio as necessary. If the content is less than 3% by weight, the concentration of lithium ions is too low to be suitable as an electrolyte. If the content is more than 40% by weight, there is a problem of solubility of lithium salts and a decrease in ion conductivity.

In the solid polymer electrolyte composition according to the present invention, the curable initiator may be any initiator such as photocurable and thermosetting which are generally used in the art.

The photo-curable initiator may be selected from the group consisting of ethyl benzoin ether, isopropyl benzoin ether,? -Methyl benzoin ethyl ether, benzoin phenyl ether,? -Acyl oxime ester,?,? -Diethoxy acetophenone, Phenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one [Darocur 1173 from Ciba Geigy], 1-hydroxycyclohexyl phenyl ketone [Ciba Irgacure 184, Daurocure 1116, Igacure 907 from Geigy), anthraquinone, 2-ethyl anthraquinone, 2-chloro anthraquinone, thioxanthone, isopropyl thioxanthone, chlorothioxanthone, benzo Phenone, p-chlorobenzophenone, benzyl benzoate, benzoyl benzoate, and microclerketone.

The thermosetting initiator may be at least one selected from the group consisting of benzoyl peroxide, di-tert-butyl peroxide, di-tert-amyl peroxide, a-cumyl peroxyneodecanoate, a-cumyl peroxyneopeptanoate, (2-ethylhexyl) peroxy-dicarbonate, t-amyl peroxypivalate, t-butyl peroxypivalate, 2,5-dimethyl-2,5 bis Ethyl-hexanoyl peroxy) hexane, dibenzoyl peroxide, t-amyl peroxy-2-ethylhexanoate, t-butyl peroxy-2-ethylhexanoate, 1,1- Amyl peroxy) cyclohexane, 1,1-di- (t-butylperoxy) 3,3,5-trimethylcyclohexane, 1,1-di- (t- butylperoxy) cyclohexane, Butyl peroxybenzoate, t-butyl peroxybenzoate, ethyl 3,3-di- (t-amylperoxy) butyrate, ethyl 3,3-di- (t-butylperoxy) butyrate, dicumylperoxide and the like Azo-bis (4-cyanovaleric acid), 4,4'-azobis (4-cyanovaleric acid) ) Can be used.

In this case, the curable initiator is contained in the total polymer electrolyte composition in the range of 0.1 to 5% by weight, and when the content is less than 0.1% by weight, there is a problem in that the effect of the initiator cannot be obtained. There is a problem that the unreacted curing initiator after curing reduces the performance of the battery.

On the other hand, the curing initiator may be appropriately adjusted according to the mixing ratio of the other components used simultaneously in the solid polymer electrolyte composition.

The solid polymer electrolyte composition according to the present invention may be used as a polymer electrolyte of an electrolyte thin film and a lithium-polymer secondary battery, but is not limited thereto.

An exemplary process for preparing an electrolyte thin film using the solid polymer electrolyte composition will be described in more detail below, but the present invention is not limited thereto.

First, the plasticizer and the lithium salt according to the present invention are placed in a container at an appropriate ratio, and stirred with a stirrer to prepare a solution, followed by addition of the cyclotriphosphazene crosslinking agent according to the present invention and mixed with each other. When a curing initiator is added to this mixed solution and stirred, a mixed solution for preparing a solid polymer electrolyte is prepared. The solution prepared above is coated on a support such as a glass plate, a polyethylene-based vinyl or a commercial Mylar film or a battery electrode to an appropriate thickness and irradiated with an electron beam, ultraviolet ray, gamma ray or the like or under a heating condition.

As another manufacturing method for obtaining a film having a constant thickness, a composition mixture is applied on the support, a spacer for thickness control is fixed on both ends of the support, another support is covered thereon, Or a heat source to produce a solid polymer electrolyte thin film.

In addition, an example process for preparing a polymer electrolyte of a lithium-polymer secondary battery, which is another application example of the solid polymer electrolyte composition according to the present invention, will be described in more detail as follows, but the present invention is not limited thereto.

Lithium-polymer secondary battery is composed of a positive electrode, an electrolyte and a negative electrode, a lithium metal oxide such as LiCoO ₂ , LiNiO ₂ is used as a positive electrode, carbon-based or lithium such as graphite or coke such as MCMB, MPCF It manufactures using a metal etc. as a material. The electrolytic solution containing the crosslinking agent, the plasticizer, the lithium salt and the curing initiator of the present invention is prepared, and then the electrolyte solution is poured into the substrate to form a film having a certain thickness. This film is dried for a predetermined time to obtain a polymer electrolyte membrane.

The method of manufacturing a lithium-polymer secondary battery may be prepared by any method commonly used in the field to which the present invention pertains, in addition to the method described above.

The solid polymer electrolyte composition containing the cyclotriphosphazene crosslinking agent according to the present invention not only greatly improves the ionic conductivity by lowering the crystallization of the ethylene oxide unit of the crosslinking agent side chain even at low temperature, but also has excellent electrochemical and thermal stability. It can be usefully used as a polymer electrolyte of a small lithium-polymer secondary battery, a power storage device for power leveling, and a large capacity lithium-polymer secondary battery.

Hereinafter, the present invention will be described in detail with reference to examples. However, the following examples are merely to illustrate the invention, but the content of the present invention is not limited by the following examples.

< Manufacturing example  1> Hexa (Ethylene glycol) Monomethyl ether ( hexa (ethylene glycol ) monomethyl  ether)

Scheme 3

Step 1: 2- (2- Methoxyethoxy Ethyl toluene-p-sulfonate (2- (2-methoxy ethoxy) ethyl toluene -p- sulfonate Manufacture of 7

Diethylene glycol monomethyl ether (10.0 g, 0.0832 mol) in 27.5 ml of THF was dissolved in a 250 ml three-neck flask. Put in. After cooling the solution to 0 ° C. and stirring, a solution of 6.75 g of NaOH (0.169 mole) dissolved in 27.5 ml of water was slowly added dropwise and 20.35 g of tosyl chloride (0.169 mole) in 27.7 ml of anhydrous THF was added to the mixture. ) Was slowly added dropwise for 15 minutes. After the dropping was completed, the mixed solution was slowly heated to room temperature and stirred for 1 hour in a nitrogen atmosphere. 375 ml of diethyl ether was added to the solution to separate the organic layer, and then washed three times with an aqueous 1 M NaOH solution and twice with distilled water using a separatory funnel. The separated organic layer was dried over MgSO ₄ and dried under reduced pressure in vacuo to give compound 7 as a colorless oil (21.82 g, 95.6%).

¹ H NMR (CDCl ₃ ), δ (ppm): 7.82 (d, 2H), 7.33 (d, 2H), 4.16 (t, 2H), 3.70 (t, 2H), 3.56 (t, 2H), 3.49 ( t, 2H), 3.34 (s, 3H), 2.44 (s, 3H)

¹³ C NMR (CDCl ₃ ), δ (ppm): 144.74, 132.88, 129.75, 127.91, 71.73, 70.60, 69.16, 68.62, 58.97, 21.56

Step 2: 2- (2- {2- [2- ( Tetrahydropyran -2- Sake ) Ethoxy ] Ethoxy } Ethoxy ) Ethanol (2- (2- {2- [2- ( tetrahydropyran -2- yloxy ) ethoxy ] ethoxy } ethoxy ) ethanol Manufacture of 8

A solution of 3,4-dihydro-2H-pyran (12.0 g, 0.143 mol) in 100 ml of dried dichloromethane was cooled to 0 ° C. and then stirred with tetraethylene glycol (41.57 g, 0.214 mol) and p- A solution of toluenesulfonic acid monohydrate (0.5488 g, 0.00286 mol) in dried dichloromethane was slowly added dropwise. After the dropwise addition, the mixed solution was raised to room temperature and stirred for 12 hours. The mixed solution was dried under reduced pressure in vacuo and purified by column chromatography using ethyl acetate / hexane as a developing solvent, to obtain compound 8 as a colorless liquid (28.0 g, 70.4%).

¹ H NMR (CDCl ₃ ), δ (ppm): 4.64 (t, 1H), 3.88-3.47 (m, 18H), 2.77 (b, 1H), 1.82-1.53 (m, 6H)

¹³ C NMR (CDCl ₃ ), δ (ppm): 98.80, 72.45, 70.53, 70.49, 70.47, 70.42, 70.26, 66.52, 62.07, 61.58, 30.42, 25.31, 19.33

Step 3: 2- ( Tetrahydropyran -2- Sake ) Hexa (Ethylene glycol) Monomethyl ether Le (2- ( tetrahydropyran -2- yloxy ) hexa ( ethylene glycol ) monomethyl ether Manufacture of 9

In a 250 ml flask, Compound 7 (7.885 g, 0.0287 mol) synthesized in Step 1 and Compound 8 (8.35 g, 0.03 mol) synthesized in Step 2 were dissolved in 100 ml of THF, followed by NaOH (11.5 g, 0.287 mol). ) Was added. Next, the mixed solution was reacted by refluxing with stirring at 100 ° C. for 24 hours. 50 ml of water was added to the mixed solution, followed by extraction with methylene chloride (3 × 250 ml). The separated organic layer was dried over MgSO ₄ and dried under reduced pressure in vacuo to obtain compound 9 as a colorless oil (7.93 g, 72.6%).

¹ H NMR (CDCl ₃ ), δ (ppm): 4.64 (t, 1H), 3.88-3.47 (m, 26H), 3.38 (s, 3H), 1.82-1.53 (m, 6H)

¹³ C NMR (CDCl 3), δ (ppm): 98.80, 71.84, 70.53, 66.52, 62.07, 58.91, 30.42, 25.31, 19.33

Step 4: Hexa (Ethylene glycol) Monomethyl ether ( hexa (ethylene glycol monomethyl ether Manufacture of 10

To a solution of compound 9 (7.93 g, 0.208 mol) synthesized in step 3 in 100 ml of anhydrous ethanol, a solution of pyridinium p-toluenesulfonate (5.24 g, 0.0208 mol) in anhydrous ethanol was slowly added dropwise. The solution was reacted by refluxing under nitrogen atmosphere for 3 hours and then dried under reduced pressure. Next, ethyl acetate / methanol was purified by column chromatography using a developing solvent, to obtain compound 10 as a colorless liquid (5.6 g, 88.7%).

¹ H NMR (CDCl ₃ ), δ (ppm): 3.73-3.57 (m, 24H), 3.38 (s, 3H), 2.62 (b, 1H)

¹³ C NMR (CDCl ₃ ), δ (ppm): 72.32, 71.75, 70.34, 70.31, 61.49, 58.89

< Manufacturing example  2> Octa (ethylene glycol) monomethyl  ether( octa ( ethylene glycol monomethyl ether Manufacturing

[Reaction Scheme 4]

Step 1: Tetra (ethylene glycol) monomethyl ether  Tosylate (tetra ( ethylene  glycol) monomethyl ether tosylate Manufacture of 12

Compound 12 was prepared (15.96 g, 91.8%) using tetra (ethylene glycol) monomethyl ether (10.0 g, 0.048 mol) in a similar manner to Step 1 of Preparation Example 1.

¹ H NMR (CDCl ₃ ), δ (ppm): 7.79 (d, 2H), 7.33 (d, 2H), 4.16 (t, 2H), 3.70-3.56 (m, 14H), 3.38 (s, 3H), 2.45 (s, 3 H)

¹³ C NMR (CDCl ₃ ), δ (ppm): 144.86, 132.99, 129.88, 128.01, 71.96, 70.76, 70.56, 69.32, 68.69, 59.08, 21.69

Step 2: 2- ( Tetrahydropyran -2- Sake ) Octa (Ethylene glycol) Monomethyl ether Le (2- ( tetrahydropyran -2- yloxy ) octa ( ethylene glycol ) monomethyl ether Manufacture of 13

In a similar manner to Step 3 of Preparation Example 1, using Compound 12 (8.0 g, 0.023 mol) prepared in Step 1 and Compound 8 (6.0 g, 0.02 mol) prepared in Step 2 of Preparation Example 1 13 was prepared (7.26 g, 71.9%).

¹ H NMR (CDCl ₃ ), δ (ppm): 4.64 (t, 1H), 3.88-3.51 (m, 32H), 3.38 (s, 3H), 1.82-1.53 (m, 6H)

¹³ C NMR (CDCl ₃ ), δ (ppm): 98.88, 71.90, 70.55, 70.50, 66.61, 62.15, 58.99, 30.54, 25.41, 19.45

Step 3: Octa (ethylene glycol) monomethyl  ether( octa ( ethylene glycol monomethyl ether Manufacture of 14

In a similar manner to Step 4 of Preparation Example 1, Compound 14 was prepared using compound 13 (7.0 g, 0.015 mol) obtained in step 2 (5.5 g, 95.7%).

¹ H NMR (CDCl ₃ ), δ (ppm): 3.73-3.55 (m, 32H), 3.38 (s, 3H), 2.36 (b, 1H)

¹³ CNMR (CDCl ₃ ), δ (ppm): 72.45, 71.90, 70.46, 70.17, 61.55, 59.01

Preparation Example 3 Preparation of Plasticizer Compound (2a) (m = 1, 3, 5, 7)

Scheme 2 below was used to prepare the cyclotriphosphazene derivative (2a) as a plasticizer.

[Reaction Scheme 2]

As a starting material, hexachlorocyclotriphosphazene (purified by recrystallization method dissolved in hexane and sublimed at 40 ° C. and 0.05 Torr) was used.

로서,In Scheme 2, R ² O ^- Na ⁺ is

as,

0.05 mol of di (ethylene glycol) when m = 1;

when m = 3, 0.05 mol of tetra (ethylene glycol);

0.05 m of hexa (ethylene glycol) when m = 5;

At m = 7, add 0.05 mol of octa (ethylene glycol) to a 500 ml cedar flask containing NaH (1.656 g, 0.0414 mol) and distill with THF (70 ml) until the NaH is completely depleted. It was refluxed and cooled to room temperature to prepare R ² O ^- Na ⁺ .

Next, the starting material hexachlorocyclotriphosphazene (2.0 g, 0.06 mol) was dissolved in THF (70 ml), and each of R ² O ^- Na ⁺ obtained above was added thereto, followed by stirring at room temperature for 2 hours. It was. Thereafter, each of the crude products were separated by filtration, the solvent was removed under reduced pressure, dissolved in dichloromethane again and washed with a small amount of water. The organic layer was then dried over anhydrous magnesium sulfate and the solvent was evaporated to separate each crude product. Finally, each of the above products was purified by passing through a silica gel column using ethyl acetate-methanol (10: 1) as eluent to prepare plasticizer compound 2a.

m = 1

¹ H NMR (CDCl ₃ ), δ (ppm): 4.07 (br, 2H), 3.69 (t, 2H), 3.64 (m, 2H), 3.5 (m, 2H), 3.33 (s, 3H)

¹³ C NMR (CDCl ₃ ), δ (ppm): 71.91, 70.53, 70.11, 64.98, 59.01

³¹ P NMR (CDCl ₃ ), δ (ppm): 18.245 (s)

m = 3

¹ H NMR (CDCl ₃ ), δ (ppm): 4.04 (br, 2H), 3.65 (t, 12H), 3.56 (m, 2H), 3.38 (s, 3H)

¹³ C NMR (CDCl ₃ ), δ (ppm): 71.91, 70.59, 70.08, 64.97, 59.03

³¹ P NMR (CDCl ₃ ), δ (ppm): 18.197 (s)

m = 5

¹ H NMR (CDCl ₃ ), δ (ppm): 3.73-3.55 (m, 24H), 3.38 (s, 3H)

¹³ C NMR (CDCl ₃ ), δ (ppm): 72.47, 71.90, 70.49, 70.47, 61.66, 59.04

³¹ P NMR (CDCl ₃ ), δ (ppm): 21.965 (s)

m = 7

¹ H NMR (CDCl ₃ ), δ (ppm): 3.73-3.55 (m, 24H), 3.38 (s, 3H)

¹³ C NMR (CDCl ₃ ), δ (ppm): 72.47, 71.90, 70.49, 70.47, 61.66, 59.04

³¹ P NMR (CDCl ₃ ), δ (ppm): 21.965 (s)

< Example  1> As a crosslinking agent Cyclotriphosphazene ( Cyclotriphosphazene ) Preparation of Derivatives (1 a, n = 1)

Scheme 1 below was used to prepare a cyclotriphosphazene derivative (1a, n = 1) as a crosslinking agent.

[Reaction Scheme 1]

Preparation step: R ³ O ^- Na ⁺ Manufacturing

이다. 이를 제조하기 위해서, 먼저 하기의 2-[2-(테트라히드로피란-2-일옥시)에톡시]에탄올을 제조하였다.In Scheme 1, R ³ O ^- Na ⁺ is an embodiment of the present invention

to be. In order to prepare this, the following 2- [2- (tetrahydropyran-2-yloxy) ethoxy] ethanol was prepared.

Specifically, a solution of 3,4-dihydro-2H-pyran (8.41 g, 0.1 mol) in 100 ml of dried dichloromethane was cooled to 0 ° C. and then stirred with di (ethylene glycol) (15.92 g, 0.15 mol) and p-toluenesulfonic acid monohydrate (2.51 g, 0.01 mol) dissolved in dried dichloromethane were slowly added dropwise. After dropping, the mixed solution was heated to room temperature, stirred for 12 hours, dried under reduced pressure in vacuo, and purified by column chromatography using ethyl acetate / hexane as a developing solvent, 2- [2- (tetrahydropyran-2). -Yloxy) ethoxy] ethanol was obtained as a colorless liquid (10.0 g, 55%).

¹ H NMR (CDCl ₃ ), δ (ppm): 4.64 (t, 1H), 3.88-3.62 (m, 10H), 2.74 (b, 1H), 1.85-1.53 (m, 6H)

¹³ CNMR (CDCl ₃ ), δ (ppm): 98.80, 72.33, 70.36, 66.68, 62.16, 61.53, 30.36, 25.19, 19.31

Next, 2- [2- (tetrahydropyran-2-yloxy) ethoxy] ethanol (5.91 g, 0.031 mol) prepared above was added to the mineral oil in which NaH (1.036 g, 0.0259 mol) was dispersed. Except that was carried out in the same manner as in Preparation Example 3, to prepare a R ³ O ^- Na ⁺ .

Step 1: Hexakeys ( Tetrahydropyran -2- Sake Ethoxyethoxy cyclotriphosphazene (hexakis ( tetrahydropyran -2- yloxy ethoxyethoxy cyclotriphosphazene Manufacture of (4)

Compound 4 was obtained by the same method as Preparation Example 3, except that R ³ O ^- Na ⁺ and hexachlorocyclotriphosphazene (1.0 g, 0.00288 mol) obtained in the preparation step were used (2.12 g, 58.1 %).

¹ H NMR (CDCl ₃ ), δ (ppm): 4.62 (t, 1H), 4.07 (t, 2H), 3.86-3.67 (m, 8H), 1.85-1.53 (m, 6H)

¹³ C NMR (CDCl ₃ ), δ (ppm): 98.80, 70.36, 69.57, 66.68, 64.57, 61.53, 30.36, 25.19, 19.31

³¹ PNMR (CDCl ₃ ), δ (ppm): 18.324 (s)

Step 2: Hexakis ( Ethoxyethanol ) Cyclotriphosphazene ( hexakis (ethoxy ethanol) cyclotriphosphazene) (5)

To a solution of compound 4 (7.93 g, 0.208 mol) obtained in step 1 in 100 ml of anhydrous ethanol, a solution of pyridinium p-toluenesulfonate (5.24 g, 0.0208 mol) in anhydrous ethanol was slowly added dropwise. The mixed solution was reacted under reflux for 3 hours in a nitrogen atmosphere, and then dried under reduced pressure. Next, the result was purified by silica column chromatography using ethyl acetate / methanol as the developing solvent, to obtain compound 5 as a colorless liquid (5.6 g, 88.7%).

¹ H NMR (CDCl ₃ ), δ (ppm): 1 HNMR: 4.13 (t, 2H), 3.71 (t, 4H), 3.60 (d, 2H), 2.89 (b, 1H)

¹³ C NMR (CDCl ₃ ), δ (ppm): 72.32, 71.75, 70.34, 61.49

³¹ P NMR (CDCl ₃ ), δ (ppm): 18.251 (s)

Step 3: As a plasticizer Cyclotriphosphazene  Preparation of Derivatives (1a, n = 1)

In a 250 ml flask, a solution of compound 5 (0.9 g, 0.00118 mol) obtained in step 2 was dissolved in 100 ml of THF and triethylamine (3 ml), followed by methacryloyl chloride (2.22 g, 0.0212 mol). ) Was slowly added dropwise. The mixture was stirred at 30 ° C. under a nitrogen atmosphere for 48 hours, after which the precipitate was separated and the organic layer was dried under reduced pressure in vacuo. The reaction mixture obtained above was purified by silica column chromatography using dichloromethane / methanol as the developing solvent, to obtain compound 1a (n = 1) as a colorless liquid (0.97 g, 70.3%).

¹ H NMR (CDCl ₃ ), δ (ppm): 6.12 (s, 1H), 5.57 (s, 1H), 4.27 (t, 2H), 4.07 (t, 2H), 3.73 (t, 4H), 1.94 ( s, 3 H)

¹³ C NMR (CDCl ₃ ), δ (ppm): 167.10, 135.92, 125.65, 69.84, 68.95, 64.88, 63.66, 18.14

³¹ P NMR (CDCl ₃ ), δ (ppm): 18.26 (s)

< Example  2> Preparation of Solid Polymer Electrolyte Composition

Crosslinking agent: compound 1a prepared in Example 1 (n = 1);

Plasticizer: compound 2a prepared in Preparation Example 3 (m = 1,3,5,7);

Curable initiators: t-amyl peroxybenzoate (APO); And

Lithium salt: LiCF ₃ SO ₃ was mixed to the content shown in Table 1, Table 2 and Table 3 of Experimental Example 1 was stirred for 1 hour at room temperature until a uniform mixture to prepare a solid polymer electrolyte composition.

< Experimental Example  1> Ion Conductivity Evaluation

In the solid polymer electrolyte composition prepared in Example 2, the ion conductivity of the electrolyte according to the length of the ethylene oxide unit of the plasticizer, the ion conductivity of the electrolyte according to the lithium salt content and the ion conductivity of the electrolyte according to the plasticizer content were measured.

Specifically, the polymer electrolyte composition is injected into a band-shaped conductive glass substrate or a lithium-copper foil, thermally cured, polymerized, sufficiently dried, and then measured AC impedance between the band-type or sandwich-type electrodes under an argon atmosphere. , The measured values were analyzed by the frequency response analyzer to obtain the complex impedance analysis method. The band-type electrode was used by attaching a masking tape having a width of about 1 mm to the center of the conductive glass (ITO) at intervals of about 2 cm, placing it in an etching solution, and then etching and washing.

The ion conductivity measurement results of the electrolyte according to the length of the ethylene oxide unit of the plasticizer are shown in Table 1 and FIG. 1,

The ion conductivity measurement results of the electrolyte according to the lithium salt content are shown in Table 2 and FIG. 2.

The ion conductivity measurement results of the electrolyte according to the plasticizer content are shown in Table 3 below.

Crosslinking agent (g)
Plasticizer (g) Lithium salt
LiCF ₃ SO ₃ (g) Curable initiator
APO (g) Ion conductivity
(S / cm,? 10 ^-4 ) Example 1 0.3 Preparation Example 3
(m = 1) 0.7 0.135 0.023 0.234 Example 1 0.3 Preparation Example 3
(m = 3) 0.7 0.135 0.023 0.583 Example 1
0.3 Preparation Example 3
(m = 5) 0.7 0.135 0.023 1.05 Example 1 0.3 Preparation Example 3
(m = 7) 0.7 0.135 0.023 1.84

Crosslinking agent (g)
Plasticizer (g) Lithium salt
LiCF ₃ SO ₃ (g) Curable initiator
APO (g) Ion conductivity
(S / cm,? 10 ^-4 ) Example 1 0.3 Preparation Example 3
(m = 5) 0.7 0.254 0.023 0.886 Example 1 0.3 Preparation Example 3
(m = 5) 0.7 0.170 0.023 1.05 Example 1
0.3 Preparation Example 3
(m = 5) 0.7 0.127 0.023 3.15 Example 1 0.3 Preparation Example 3
(m = 5) 0.7 0.102 0.023 2.11

Crosslinking agent (g)
Plasticizer (g) Lithium salt
LiCF ₃ SO ₃ (g) Curable initiator
APO (g) Ion conductivity
(S / cm,? 10 ^-4 ) Example 1 0.4 Preparation Example 3
(m = 5) 0.6 0.161 0.023 0.725 Example 1 0.3 Preparation Example 3
(m = 5) 0.7 0.161 0.023 1.05 Example 1
0.2 Preparation Example 3
(m = 5) 0.8 0.161 0.023 2.55

1 is a graph showing the ionic conductivity of an electrolyte according to the temperature according to the length of the ethylene oxide unit of the plasticizer.

2 is a graph showing the change in ion conductivity of an electrolyte according to the lithium salt content. At this time, in [EO] / [Li ⁺ ] shown on the X-axis of FIG. 2, [EO] is the number of ethylene oxide units present in the electrolyte, and [Li ⁺ ] is lithium-ion water. That is, as the value of [EO] / [Li ⁺ ] increases, the content of lithium salt decreases.

As shown in Table 1 and Figure 1, the longer the ethylene oxide unit length of the plasticizer was confirmed that the ion conductivity increases. When the compound of the manufacture example 3 (m = 7) with the longest ethylene oxide unit length of a plasticizer was used, it was confirmed that ionic conductivity is the highest as 1.84 S / cm and (sigma) x10 <^-4> .

In addition, as shown in Table 2 and Figure 2, it was confirmed that the ionic conductivity is changed according to the change in the content of the lithium salt, it can be seen that the highest ionic conductivity when using the lithium salt 0.127 g.

Further, as shown in Table 3, it was confirmed that the ion conductivity increases as the content of the plasticizer increases.

Therefore, the polymer electrolyte composition according to the present invention can not only improve the ion conductivity by adjusting the length, the lithium salt content and the plasticizer content of the ethylene oxide unit of the plasticizer, but also have excellent ion conductivity even at low temperature, and thus, lithium-polymer secondary It can be usefully used as a polymer electrolyte of a battery.

Claims (10)

Cyclotriphosphazene crosslinking agent for a solid polymer electrolyte thin film represented by Formula 1 below:
[Formula 1]

(In Formula 1,
R ¹ is

ego,
n is an integer of 0-2).
As shown in Scheme 1 below, a compound 4 is prepared by alkoxylation of an R ³ substituent to hexachlorocyclotriphosphazene, which is a starting material (step 1);
Preparing compound 5 by treating compound 4 obtained in step 1 with pyridinium p-toluenesulfonate (step 2); And
A method for preparing a cyclotriphosphazene crosslinking agent for a solid polymer electrolyte thin film according to claim 1, comprising the step of preparing compound 1 by reacting compound 5 obtained in step 2 with triethylamine and methacryloyl chloride (step 3). :
[Reaction Scheme 1]

(In the above Reaction Scheme 1,
R ³ is

ego,
y is an integer from 0-2,
R ⁴ is

ego,
z is an integer from 0-2,
R ¹ is as defined in formula (I) of claim 1).
0.1 to 95% by weight of a cyclotriphosphazene crosslinking agent represented by Formula 1;
0.1 to 96.8% by weight of a plasticizer represented by Chemical Formula 2;
3-40% by weight of lithium salt; And
A solid polymer electrolyte composition comprising 0.1 to 5 wt% of a curing initiator:
[Formula 1]

(In Formula 1, R ¹ is as defined in Formula 1 of claim 1);
(2)

(In the formula (2)
R ² is

ego,
m is an integer of 3-9).
The method of claim 3, wherein the plasticizer may further comprise a non-aqueous polar solvent, wherein the non-aqueous polar solvent is ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, tetrahydrofuran, 2-methyltetra Solid polymer electrolyte composition, characterized in that at least one selected from the group consisting of hydrofuran, 1,3-dioxirane, 4,4-dimethyl-1,3-dioxirane, γ-butyrolactone and acetonitrile .
The solid according to claim 3, wherein the lithium salt is at least one selected from the group consisting of LiClO ₄ , LiCF ₃ SO ₃ , LiBF ₄ , LiPF ₆ , LiAsF _6, and Li (CF ₃ SO ₂ ) ₂ N. Polymer electrolyte composition.
The method of claim 3,
14.4-20.4% by weight of a cyclotriphosphazene crosslinking agent represented by Chemical Formula 1;
66.5-72.5 wt% of a plasticizer represented by Chemical Formula 2;
Lithium salt 9.7-13.0 wt%; And
Solid polymer electrolyte composition comprising; 1.0-3.0% by weight of a curing initiator.
The method of claim 3, wherein the curing initiator is ethylbenzoin ether, isopropylbenzoin ether, α-methylbenzoin ethyl ether, benzoin phenyl ether, α-acyl oxime ester, α, α-diethoxy acetophenone, 1 , 1-dichloroacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, anthraquinone, 2-ethyl anthraquinone, 2-chloroanthraquinone, thi At least one photocurable initiator selected from the group consisting of oxanthone, isopropyl thioxanthone, chlorothioxanthone, benzophenone, p-chlorobenzophenone, benzyl benzoate, benzoyl benzoate and mickle ketone Solid polymer electrolyte composition.
The method of claim 3, wherein the curing initiator is benzoyl peroxide, di-tert-butyl peroxide, di-tert-amyl peroxide, a- cumyl peroxy neodecanoate, a- cumyl peroxy neopeptanoate, t-amyl peroxyneodecanoate, di- (2-ethylhexyl) peroxy-dicarbonate, t-amyl peroxypivalate, t-butyl peroxypivalate, 2,5-dimethyl-2,5 Bis (2-ethyl-hexanoylperoxy) hexane, dibenzoyl peroxide, t-amyl peroxy-2-ethylhexanoate, t-butyl peroxy-2-ethylhexanoate, 1,1-di- (t-amylperoxy) cyclohexane, 1,1-di- (t-butylperoxy) 3,3,5-trimethyl cyclohexane, 1,1-di- (t-butylperoxy) cyclohexane, t -Butyl peroxyacetate, t-butyl peroxybenzoate, t-amyl peroxybenzoate, t-butyl peroxybenzoate, ethyl 3,3-di- (t-amylperoxy) butyrate, ethyl 3,3 -Di- (t-butylperoxy) butyrate, dicumyl peroxide, 1,1 Selected from the group consisting of '-azobis (cyclohexanecarbonitrile), 2,2'-azobis (2-methylpropionamidine) dihydrochloride and 4,4'-azobis (4-cyanovaleric acid) Solid polymer electrolyte composition, characterized in that at least one thermosetting initiator.
A solid polymer electrolyte thin film coated with the solid polymer electrolyte composition of any one of claims 3 to 8.
A lithium-polymer secondary battery comprising the solid polymer electrolyte composition of any one of claims 3 to 8.

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