JP2001155771A - Electrolyte for the secondary battery and secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolyte for a secondary battery, made of polymer as materials for an electrochemical device that exhibits high ion conductivity and safety, and a secondary battery using the electrolyte that may improve the charge and discharge cycle properties. SOLUTION: An electrolyte for a secondary battery consists of an ionic compound and an organic polymer compound, characterized in that the organic polymer compound contains ester of boric acid. A secondary battery using the above electrolyte is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrolyte for a secondary battery which is a polymer electrolyte and a secondary battery using the electrolyte for a secondary battery, and more particularly to an electrochemical device such as a battery having a high ionic conductivity. The present invention relates to an electrolyte for a secondary battery, which is a polymer electrolyte useful as a material for the secondary battery, and a secondary battery using the electrolyte.

[0002]

2. Description of the Related Art In recent years, there has been a strong demand for higher performance and smaller size of electronic products, and battery materials as energy sources have been required to be smaller, lighter, have higher capacity and higher energy density. Various research and developments are underway.

In recent years, lithium ion secondary batteries have been used as an energy source for such electronic products. In general, a lithium ion secondary battery has a structure in which a metal oxide is used as a positive electrode, a carbon material or the like is used as a negative electrode, and a separator and an electrolyte are sandwiched between the electrodes. This is a secondary battery with a high energy density, but because of the use of electrolyte, there is a problem in safety due to the problem of liquid leakage, and furthermore, it is necessary to use a metal can as an exterior to prevent liquid leakage , Weight reduction is difficult. In order to overcome the drawbacks of using an electrolytic solution, various types of so-called polymer electrolytes using a polymer compound as an electrolyte have been studied. The polymer electrolyte has the characteristic that it has flexibility, can follow mechanical shock, and can follow the change in the volume of the electrode caused by the ion-electron exchange reaction between the electrode and the electrolyte.

[0004]

As such a polymer electrolyte, US Pat. No. 4,303,748 proposes a solid electrolyte obtained by dissolving an alkali metal salt or an alkali metal salt in a polyalkylene oxide. However, there remains a problem that the contact resistance with the electrode material is high. If the ionic conductivity is insufficient as described above, a sufficient current density during charging and discharging cannot be obtained, and the application cannot be applied to applications requiring a large current, and the applications are limited. On the other hand, a system called a so-called gel electrolyte in which an organic polymer compound is impregnated with a non-aqueous organic solvent is disclosed in JP-B-61-23945, JP-B-61-23947, and US Pat.
39 and US Pat. No. 5,429,891. In such a gel electrolyte, the electrolyte is in the form of being included in a polymer compound serving as a matrix, and is responsible for ionic conductivity. However, there is a problem that the retention of the electrolyte is lost or deteriorated due to the temperature change. Furthermore, in order to obtain a high ionic conductivity, it is necessary to impregnate a larger amount of the electrolyte into the polymer compound. Is concerned. The present invention has a high ionic conductivity, and is a polymer electrolyte useful as a material for an electrochemical device such as a secondary battery, which is excellent in safety, and a secondary battery electrolyte and excellent cycle characteristics using the electrolyte. Another object of the present invention is to provide a secondary battery.

[0005]

The present invention relates to (a) an electrolyte for a secondary battery comprising an ionic compound and an organic polymer compound, wherein the organic polymer compound comprises a compound represented by the formula (1): An electrolyte for a secondary battery, comprising a borate compound obtained by esterification with an acid or boric anhydride, wherein Z ¹ -[(A ¹ O) ₁ -H] _a (1) (Z ¹ is a residue of a compound having ¹ to 6 hydroxyl groups, A ¹ O is ^one or a mixture of two or more oxyalkylene groups having 2 to 4 carbon atoms, 1 = 0 to 600, a = 1 to 6, and la = 0 to 600.)

(A) The electrolyte for a secondary battery according to (A), wherein the organic polymer compound comprises a borate ester compound and a polymer of the compound represented by the formula (2), wherein Z ² -[(A ^{2 _{O) m -R 1] b (}} 2) (Z 2 is a residue or hydroxyl compounds having 1-4 hydroxyl groups, a ² O is one or oxyalkylene group having 2 to 4 carbon atoms A mixture of more than one species, m = 0-15
0, b = 1 to 4 and mb = 0 to 300,
R ¹ is a hydrogen atom or a group represented by the formula (3). )

[0007]

Embedded image

(R ² and R ³ are a hydrogen atom or a methyl group.)

(C) The electrolyte for a secondary battery according to (A), wherein the organic polymer compound comprises a borate compound and a compound represented by the formula (4): Z ³ -[(A ³ O) _n —H] _c (4) (Z ³ is a residue of a compound having 1 to 6 hydroxyl groups, A ³ O is one or a mixture of two or more oxyalkylene groups having 2 to 4 carbon atoms, and n = 100-150,000, c =
1 to 6 and nc = 100 to 150,000. )

(D) The electrolyte for a secondary battery according to (A), (A) or (C), wherein the ionic compound is an alkali metal salt,

(E) A secondary battery characterized by using the electrolyte for a secondary battery described in (A), (A), (C) or (D).

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In the compound represented by the formula (1) serving as a substrate of a borate compound used in the present invention,
Z ¹ is a residue of a compound having ¹ to 6 hydroxyl groups. 1
Compounds having up to 6 hydroxyl groups include methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, n-butyl alcohol, 2-butyl alcohol, t-butyl alcohol, n-hexyl alcohol, n-octyl alcohol, and isooctyl. Alcohol, decyl alcohol, dodecyl alcohol, tridecyl alcohol, tetradecyl alcohol, hexadecyl alcohol, octadecyl alcohol, octadecenyl alcohol, icosyl alcohol, monool such as tetricosyl alcohol, ethylene glycol, propylene glycol, butanediol Diols such as pentanediol, hexanediol and octanediol, triols such as glycerin and trimethylolpropane, pentaerythritol Including tetraols diglycerol and the like, preferably a compound having 1 to 24 carbon atoms, more preferably a compound having 1-4 hydroxyl groups of 1 to 5 carbon atoms.

The oxyalkylene group having 2 to 4 carbon atoms represented by A ¹ O includes an oxyethylene group, an oxypropylene group, an oxybutylene group and an oxytetramethylene group, and is preferably an oxyethylene group or an oxypropylene group. It is. One or a mixture of two or more of these may be used, and when two or more of them are used, the polymerization form may be either block-like or random. 1 is the average number of moles of the added oxyalkylene group having 2 to 4 carbon atoms,
0, preferably 0 to 100. If it exceeds 600, the amount of the borate ester bond introduced becomes small, and it becomes difficult to obtain high ionic conductivity. a is 1 to 6, preferably 1 to 4. la is 0 to 600, preferably 0 to 100. If it exceeds 600, the amount of the borate ester bond introduced becomes small, and it becomes difficult to obtain high ionic conductivity.

The compound represented by the formula (1) serving as a substrate of the borate ester used in the present invention can be obtained by conventionally known ring-opening polymerization. For example, 1-6
Compounds having two hydroxyl groups include conventionally known alkali metal salts such as sodium hydroxide, potassium hydroxide, lithium hydroxide and sodium methylate, boron trifluoride etherate, tin tetrachloride, aluminum trichloride and the like. It can be synthesized by polymerizing alkylene oxides having 2 to 4 carbon atoms such as ethylene oxide, propylene oxide, butylene oxide and tetrahydrofuran at a predetermined molar ratio using a ring-opening polymerization catalyst such as a Lewis acid.

The borate compound used in the present invention is obtained by adding a boric acid such as orthoboric acid, metaboric acid or pyroboric acid or a boric anhydride to the compound represented by the formula (1) and inactivating at 50 to 200 ° C. It is obtained by performing a dehydration reaction by vacuum under gas ventilation. For example, a reaction temperature of 60 to 1
At 20 ° C. under a vacuum of 10 to 50 mmHg, an appropriate amount of nitrogen gas is passed and a dehydration reaction is performed for 2 to 12 hours with stirring to produce a borate compound.

The polyalkylene oxide boric acid triester is formed at a ratio of 1/3 mole of boron atom to 1 mole of hydroxyl group of the compound represented by the formula (1). Although the ratio of boric acid esterification can be arbitrarily adjusted by the molar ratio of hydroxyl group to boron atom, the molar ratio of hydroxyl group to boron atom of the compound represented by the formula (1) is preferably 6/1 to 3 /. 1 range. Further, when the compound represented by the formula (1) contains two or more hydroxyl groups, formation of a network polymer may occur with the progress of boric acid esterification, so that the fluidity of the reaction system is maintained. It is desirable to appropriately use a solvent that is not involved in the esterification reaction.
The content of the borate compound in the organic polymer compound is preferably 10 to 95 parts by weight, more preferably 20 to 80 parts by weight.

The borate ester compound used in the present invention is used in a mixed system in which a polymer of the compound represented by the formula (2) is used as a matrix for the purpose of imparting flexibility which is a characteristic of a polymer electrolyte. Is preferred.

In the compound of the formula (2) used in the present invention, Z ² is a residue of a compound having 1 to 4 hydroxyl groups or a hydroxyl group. Compounds having 1 to 4 hydroxyl groups include methyl alcohol, ethyl alcohol,
Propyl alcohol, isopropyl alcohol, n-butyl alcohol, 2-butyl alcohol, t-butyl alcohol, n-hexyl alcohol, n-octyl alcohol, isooctyl alcohol, decyl alcohol,
Monools such as dodecyl alcohol, tridecyl alcohol, tetradecyl alcohol, hexadecyl alcohol, octadecyl alcohol, octadecenyl alcohol, icosyl alcohol, tetricosyl alcohol,
Diols such as ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol and octanediol, triols such as glycerin and trimethylolpropane, tetraols such as pentaerythritol and diglycerin, acrylic acid, methacrylic acid and crotonic acid Examples thereof include a polymerizable group-containing compound. Z ² is preferably a hydroxyl group, methyl alcohol, ethylene glycol, propylene glycol, glycerin, trimethylolpropane, pentaerythritol, diglycerin, a residue of acrylic acid and methacrylic acid, more preferably a hydroxyl group, or methyl alcohol, ethylene Glycol, propylene glycol,
It is a residue of acrylic acid and methacrylic acid.

Examples of the oxyalkylene group having 2 to 4 carbon atoms represented by A ² O include an oxyethylene group, an oxypropylene group, an oxybutylene group, an oxytetramethylene group and the like, preferably an oxyethylene group or an oxypropylene group. It is. One or a mixture of two or more of these may be used, and when two or more of them are used, the polymerization form may be either block-like or random. m is the average number of moles of the oxyalkylene group having 2 to 4 carbon atoms, and 0 to 15
0, preferably 5 to obtain ionic conductivity.
100. If it exceeds 150, the amount of the polymerizable group introduced is small, and it becomes difficult to obtain mechanical strength as a matrix. b is 1 to 4, preferably 1 to 3. mb
Is 0 to 300, preferably 0 to 150. Three
If it exceeds 00, the amount of the polymerizable group represented by the formula (3) is small, and it is difficult to obtain a mechanical strength as a matrix.

R ¹ is a hydrogen atom or a group represented by the formula (3). When there are two or more R ^{1 s} , they may be the same or different. In the group represented by the formula (3), R ² and R ³ are a hydrogen atom or a methyl group. R
^An acryloyl group in which ² and R ³ are hydrogen atoms or R ²
Is preferably a hydrogen atom and R ³ is a methyl group. The polymer of the compound represented by the formula (2) is a polymer polymerized by the polymerizable group represented by the formula (3). Formula (2) has at least one polymerizable group. Specifically, when Z ² is not a residue of a polymerizable group-containing compound such as acrylic acid, methacrylic acid, crotonic acid, at least one of R ¹ has a polymerizable group represented by the formula (3).

The compound represented by the formula (2) used in the present invention is obtained by esterification of an alkylene oxide derivative with an organic acid having a polymerizable group, or ring-opening polymerization of the alkylene oxide to an organic acid having a polymerizable group. Can be obtained at For example, it can be obtained by reacting an alkylene oxide derivative with an organic acid having a polymerizable group at a predetermined molar ratio using a conventionally known esterification catalyst, or an organic acid having a polymerizable group. In addition, it can be obtained by polymerizing an alkylene oxide such as ethylene oxide, propylene oxide, butylene oxide and tetrahydrofuran at a predetermined molar ratio using a conventionally known ring-opening polymerization catalyst. The compound represented by the formula (2) can be used alone or in combination of two or more. The mixing ratio of the borate compound to the compound represented by the formula (2) is preferably 10/90 to 95 / weight ratio for the purpose of imparting flexibility as a polymer electrolyte and obtaining high ionic conductivity. 5, more preferably 20/8
0 to 80/20.

The compound represented by the formula (2) used in the present invention is used in a form in which a polymerizable group contained therein is polymerized. Polymerization is performed by energy such as heating, ultraviolet light, visible light, and electron beam, but a known polymerization initiator may be used as appropriate. The number average molecular weight after the polymerization is preferably from 50,000 to 10,000,000, and if it is less than 50,000, it is difficult to obtain the flexibility characteristic of a polymer electrolyte, and it is difficult to obtain 10,000,000. 0
If it exceeds 00, it may be an obstacle to ion conduction.

The borate compound used in the present invention is preferably used in a mixed system in which the compound represented by the formula (4) is used as a matrix for the purpose of imparting flexibility which is a characteristic of the polymer electrolyte. .

In the compound of the formula (4) used in the present invention, Z ³ is a residue of a compound having 1 to 6 hydroxyl groups. As the compound having 1 to 6 hydroxyl groups,
Methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, n-butyl alcohol, 2-butyl alcohol, t-butyl alcohol, n
Hexyl alcohol, n-octyl alcohol, isooctyl alcohol, decyl alcohol, dodecyl alcohol, tridecyl alcohol, tetradecyl alcohol, hexadecyl alcohol, octadecyl alcohol, octadecenyl alcohol, icosyl alcohol,
Monools such as tetricosyl alcohol, diols such as ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol and octanediol, triols such as glycerin and trimethylolpropane, and tetraols such as pentaerythritol and diglycerin. And preferably has 1 to 1 carbon atoms.
24 compounds, and more preferably a compound having 1 to 4 carbon atoms.

A ³ O is an oxyalkylene group having 2 to 4 carbon atoms, such as an oxyethylene group, an oxypropylene group, an oxybutylene group and an oxytetramethylene group, and preferably an oxyethylene group or an oxypropylene group. is there. One or a mixture of two or more of these may be used, and when two or more of them are used, the polymerization form may be either block-like or random. n is the average number of moles of the oxyalkylene group having 2 to 4 carbon atoms, and 100 to 150,
000, preferably 200 to 120,000. If it is less than 100, fluidity is exhibited when an ionic compound is blended, and it is difficult to obtain an effect as a matrix. If it exceeds 150,000, it may be difficult to use a borate compound or a solvent used for forming an electrolyte film. The solubility is insufficient, which is not preferable. c is 1 to 6, preferably 1 to 4. nc is 100 to 150,000, preferably 200 to 120,000. 10
If it is smaller than 0, the fluidity is developed when the ionic compound is blended, and it is difficult to obtain the effect as a matrix.
If it exceeds 50,000, the solubility in a solvent used for producing a borate compound or an electrolyte film is insufficient, which is not preferable. Borate compound and formula (4)
The mixing ratio with the compound represented by is preferably from 10/90 to 95/5 by weight, more preferably from 20/95, for the purpose of imparting flexibility as a polymer electrolyte and obtaining high ionic conductivity. 80 to 80/20.

The compound represented by the formula (4) used in the present invention can be obtained by conventionally known ring-opening polymerization. For example, it can be synthesized by polymerizing an alkylene oxide such as ethylene oxide, propylene oxide, butylene oxide, or tetrahydrofuran at a predetermined molar ratio using a conventionally known ring-opening polymerization catalyst on an active hydrogen-containing compound.

The ionic compound used in the present invention can be mixed with the organic polymer compound used in the present invention at an arbitrary ratio. One mole of the alkali metal contained in the ionic compound used in the present invention is mixed so that the total number of oxyalkylene units contained in the organic polymer compound used in the present invention is 2 to 30 mol. Preferably, mixing is performed so that the total number of oxyalkylene units is 2 to 15 moles per mole of alkali metal, from the viewpoint of contribution to ionic conductivity due to a decrease in glass transition temperature of the organic polymer compound. preferable. Examples of the ionic compound include LiClO ₄ , LiAs
F ₆ , LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , Li
(CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N, Li
(CF ₃ SO ₂ ) ₃ C, LiI, LiSCN, NaBr,
Examples thereof include alkali metal salts such as NaI, NaSCN, KI, and KSCN, preferably LiClO ₄ , LiAs
F ₆ , LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , Li
(CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N, Li
(CF ₃ SO ₂ ) ₃ C, LiI, LiSCN and other lithium salts.

Further, an ion-conductive or ferroelectric salt, glass powder or the like can be added to the polymer electrolyte of the present invention. Examples of such salt or glass powder include SnO ₂ , BaTiO ₃ , Al ₂ O ₃ , and Li ₂
Such as _{O · 3B 2 O 3, LaTiO} 3 , and the like.

The polymer electrolyte of the present invention can be prepared by various methods. Although the preparation method is not particularly limited, for example, the borate compound used in the present invention is dissolved in many low-boiling organic solvents, so that the borate compound, the ionic compound and the polymerizable organic compound can be dissolved in a low-boiling solvent. A polymer electrolyte thin film having mechanical strength can be obtained by thermally dissolving the polymerizable organic compound while removing the low-boiling solvent by casting the solution. If necessary, ultraviolet light, visible light,
By irradiating an electromagnetic wave such as an electron beam, a thin film can be obtained by polymerization of a polymerizable organic compound. Further, for example, the borate compound, the ionic compound and the high molecular compound of the present invention are dissolved in a low-boiling solvent to prepare a solution, and the solution is cast to remove the low-boiling solvent. Can be obtained. As long as the effect of the present invention is not impaired, there is no problem even if other organic polymer compounds are mixed and used. Other organic polymer compounds include, for example, polyacrylonitrile, acrylonitrile-methacrylic acid copolymer, acrylonitrile-methyl methacrylate copolymer, methacrylic acid-styrene copolymer, acrylonitrile-styrene copolymer, acrylonitrile-styrene-methacrylic An acid copolymer, an acrylonitrile-styrene-methyl methacrylate copolymer and the like can be mentioned.

For example, an organic solvent which can serve as a plasticizer is added to the above-mentioned solution to prepare a solution, and the solution is cast to remove a low-boiling solvent and to thermally polymerize a polymerizable organic compound, thereby obtaining a polymer gel electrolyte thin film. Can be obtained. Further, a solution is prepared by dissolving the borate ester compound and the polymerizable organic compound of the present invention in a low-boiling solvent,
A polymer gel electrolyte thin film is obtained by impregnating the polymer solid thin film obtained by thermally polymerizing the polymerizable organic compound while removing the low boiling point solvent by casting it with an organic solvent in which an ionic compound is dissolved. You can also. If necessary, a thin film obtained by polymerizing a polymerizable organic compound can be obtained by irradiating electromagnetic waves such as ultraviolet rays, visible light, and electron beams.

By combining the polymer electrolyte of the present invention with conventionally known cathode and anode materials,
A secondary battery having excellent ion conductivity, charge / discharge cycle characteristics, and safety can be obtained.

[0032]

The present invention will be described below in detail with reference to examples. In the following text, LiTFSI indicates lithium bis (trifluoromethanesulfonate) imide.
Further, in each of Examples and Comparative Examples except Comparative Example 3, 8 moles of oxyalkylene units contained in the boric acid ester compound, the compound represented by the formula (2) or the formula (4) were added to the ionic compound. Contains 1 alkali metal
The molar ratio was adjusted.

Production Example 1 550 g (1.0 mol) of methoxypolyethylene glycol having a molecular weight of 550 as a starting material was added to 11.6 of boric anhydride.
g (0.167 mol) and added under a nitrogen gas atmosphere.
The temperature was raised to ° C. After the temperature reached 110 ° C., the pressure inside the system was gradually reduced, and a state of a pressure of 20 mmHg or less was maintained for 3 hours.
Water generated with the progress of the reaction was removed. Thereafter, filtration was performed to obtain a borate compound (1).

Production Example 2 600 g (1.0 mol) of polyethylene glycol having a molecular weight of 600 as a starting material and toluene 60 as a reaction solvent
After adding 0 ml, 23.2 g of boric anhydride (0.33
3 mol), and the temperature was raised to 110 ° C. in a nitrogen gas atmosphere. The reaction system was equipped with a reflux tube and a water separation tube,
The reflux of the volatilized toluene and the generated water can be separated by the difference in specific gravity from the toluene. After the temperature reached 110 ° C., the pressure inside the system was gradually reduced, and the pressure was kept at 20 mmHg or less for 3 hours to remove water generated as the reaction progressed. The toluene solution of the obtained borate compound was filtered, and the solution was put in a stainless steel boat.
Toluene was distilled off by maintaining the temperature for 12 hours or less under the condition of Hg or less to obtain a borate compound (2).

Preparation Example 3 To 750 g (1.0 mol) of tris polyethylene glycol glycerol ether having a molecular weight of 750 as a starting material, 600 ml of toluene was added as a reaction solvent, and 34.8 g (0.5 mol) of boric anhydride was added. The temperature was raised to 110 ° C. in a nitrogen gas atmosphere. A reflux tube and a water separation tube were attached to the reaction system so that the reflux of the volatilized toluene and the generated water could be separated by the difference in specific gravity from the toluene. After the temperature reached 110 ° C., the pressure inside the system was gradually reduced, and the pressure was kept at 20 mmHg or less for 3 hours to remove water generated as the reaction progressed. The toluene solution of the obtained borate compound was filtered, the solution was put in a stainless steel boat, and the stainless steel boat was kept in a vacuum dryer at 120 ° C. and 10 mmHg or less for 12 hours to distill off toluene. Thus, a borate compound (3) was obtained.

Production Example 4 1000 g of tetrakis polyethylene glycol pentaerythritol ether having a molecular weight of 1000 as a starting material
After adding 600 ml of toluene as a reaction solvent to (1.0 mol), 46.4 g (0.67 mol) of boric anhydride was added, and the temperature was raised to 110 ° C. under a nitrogen gas atmosphere. A reflux tube and a water separation tube were attached to the reaction system so that the reflux of the volatilized toluene and the generated water could be separated by the difference in specific gravity from the toluene. After the temperature reached 110 ° C., the pressure in the system was gradually reduced.
The solution was kept for a time, and water generated as the reaction proceeded was removed. The toluene solution of the obtained borate compound was filtered, the solution was put in a stainless steel boat, and the stainless steel boat was kept in a vacuum dryer at 120 ° C. and 10 mmHg or less for 12 hours to distill off toluene. Thus, a borate compound (4) was obtained.

Production Example 5 1.74 g (0.025 mol) of boric anhydride was added to 600 g (0.15 mol) of methoxypolyethylene glycol having a molecular weight of 4000 as a starting material, and the temperature was raised to 110 ° C. in a nitrogen gas atmosphere. After the temperature reached 110 ° C., the pressure inside the system was gradually reduced, and the pressure was kept at 20 mmHg or less for 3 hours to remove water generated as the reaction progressed. Thereafter, filtration was performed to obtain a borate compound (5).

Production Example 6 As starting materials, 600 g (0.15 mol) of methoxypolyethylene-propylene glycol (ethylene oxide / propylene oxide = 50/50 weight ratio) having a molecular weight of 4,000 were added to 1.74 g (0.025 mol) of boric anhydride. Was added, and the temperature was raised to 110 ° C. in a nitrogen gas atmosphere. 110 ° C
After that, the pressure inside the system was gradually reduced to 20 mmHg.
The following conditions were maintained for 3 hours to remove water generated with the progress of the reaction. Thereafter, filtration was performed to obtain a borate compound (6).

Example 1 The borate ester compound (1) obtained in Production Example 1 was 3.0
For 0 g, Blemmer PE-35 manufactured by NOF Corporation
0 (polyethylene glycol (350) monomethacrylate) was mixed with 2.00 g, and LiTFSI was used as a supporting salt.
3.98 g was added and uniformly dissolved, then poured into a Teflon boat, thermally polymerized at 110 ° C. on a hot plate under an argon atmosphere, and dried under vacuum to form a 0.50 mm thick secondary battery. An electrolyte was obtained.

Example 2 The borate compound (1) obtained in Production Example 1 (3.0)
0 g, Blemmer PDE-6 manufactured by NOF Corporation
00 (polyethylene glycol (600) dimethacrylate) as a supporting salt.
Was added and melted uniformly, then poured into a Teflon boat, thermally polymerized at 110 ° C. on a hot plate under an argon atmosphere, and dried by vacuum to form a 0.50 mm thick secondary battery. An electrolyte was obtained.

Example 3 The borate compound (1) obtained in Production Example 1 (2.0)
0 g, Blenmer PME-4 manufactured by NOF Corporation
00 (methoxypolyethylene glycol (400) methacrylate) was mixed with 3.00 g, and LiT was used as a supporting salt.
After adding 3.98 g of FSI and dissolving uniformly, pour into a Teflon boat, thermally polymerize at 110 ° C on a hot plate under an argon atmosphere, and dry by vacuum to obtain a 0.50 mm thick secondary. An electrolyte for a battery was obtained.

Example 4 Borate compound (1) 3.5 obtained in Production Example 1
0 g, Blemmer PDE-6 manufactured by NOF Corporation
0.75 g of 00 (polyethylene glycol (600) dimethacrylate), Blemmer PM manufactured by NOF Corporation
E-4000 (methoxypolyethylene glycol (40
After mixing 0.75 g of (00) methacrylate), adding 3.21 g of LiTFSI as a supporting salt and uniformly dissolving the mixture, pouring the mixture into a Teflon boat, and performing thermal polymerization at 110 ° C. on a hot plate under an argon atmosphere; By drying in a vacuum, an electrolyte for a secondary battery having a thickness of 0.50 mm was obtained.

Example 5 Boric ester compound (1) obtained in Production Example 1 (3.0)
0 g, Blemmer PDE-6 manufactured by NOF Corporation
1.00 g of polyethylene glycol (600) dimethacrylate, manufactured by NOF Corporation
E-4000 (methoxypolyethylene glycol (40
1.00 g of (00) methacrylate), 3.77 g of LiTFSI was added as a supporting salt, and after uniformly dissolving, it was poured into a Teflon boat and thermally polymerized at 110 ° C. on a hot plate under an argon atmosphere. By drying in a vacuum, an electrolyte for a secondary battery having a thickness of 0.50 mm was obtained.

Example 6 Boric ester compound (1) obtained in Production Example 1 (3.0)
For 0 g, Blemmer PE-35 manufactured by NOF Corporation
1.00 g of polyethylene glycol (350) monomethacrylate), and 1.35 g of lithium perchlorate as a supporting salt was added and uniformly dissolved. The mixture was poured into a Teflon boat and placed on a hot plate under an argon atmosphere. At 110 ° C. and dried under vacuum to obtain a 0.50 mm thick electrolyte for a secondary battery.

Example 7 Boric ester compound (1) obtained in Production Example 1 (3.0)
0 g, Blemmer PDE-6 manufactured by NOF Corporation
2.00 g of poly (ethylene glycol (600) dimethacrylate), 1.33 g of lithium perchlorate as a supporting salt was added, and the mixture was uniformly dissolved. The mixture was poured into a Teflon boat and placed on a hot plate under an argon atmosphere. At 110 ° C. and dried under vacuum to obtain a 0.50 mm thick electrolyte for a secondary battery.

Example 8 The borate compound (1) obtained in Production Example 1 (3.0)
0 g, Blenmer PME-4 manufactured by NOF Corporation
After mixing 2.00 g of 00 (methoxypolyethylene glycol (400) methacrylate) and adding 1.36 g of lithium perchlorate as a supporting salt and uniformly dissolving,
The mixture was poured into a Teflon boat, thermally polymerized at 110 ° C. on a hot plate under an argon atmosphere, and dried under vacuum to obtain a 0.50 mm thick electrolyte for a secondary battery.

Example 9 The borate compound (1) obtained in Production Example 1 (3.0)
0 g, Blemmer PDE-6 manufactured by NOF Corporation
1.00 g of polyethylene glycol (600) monomethacrylate, Blemmer P manufactured by NOF Corporation
ME-4000 (methoxypolyethylene glycol (4
000) methacrylate), and 1.40 g of lithium perchlorate as a supporting salt was added and uniformly dissolved. The mixture was poured into a Teflon boat, and heated at 110 ° C. on a hot plate under an argon atmosphere. By polymerizing and drying by vacuum, an electrolyte for a secondary battery having a thickness of 0.50 mm was obtained.

Example 10 The borate compound (1) obtained in Production Example 1 (2.0)
To 0 g, 2.00 g of polyethylene oxide (500,000) manufactured by Wako Pure Chemical Industries, Ltd. was mixed and added to 10.0 g of acetonitrile to form a solution, and 1.21 g of lithium perchlorate was added as a supporting salt, After dissolving uniformly,
The mixture was poured into a Teflon boat, heated at 110 ° C. on a hot plate under an argon atmosphere, and the solvent was evaporated by vacuum to obtain a 0.50 mm thick electrolyte for a secondary battery.

Example 11 Borate ester compound (1) obtained in Production Example 1 (1.5)
To 0 g, 3.00 g of polyethylene oxide (500,000) manufactured by Wako Pure Chemical Industries, Ltd. was mixed, and added to 15.0 g of acetonitrile to form a solution, and 1.36 g of lithium perchlorate as a supporting salt was added. After dissolving uniformly,
The mixture was poured into a Teflon boat, heated at 110 ° C. on a hot plate under an argon atmosphere, and the solvent was evaporated by vacuum to obtain a 0.50 mm thick electrolyte for a secondary battery.

Example 12 The borate compound (2) obtained in Production Example 2 (2.0)
To 0 g, 2.00 g of polyethylene oxide (500,000) manufactured by Wako Pure Chemical Industries, Ltd. was mixed and added to 10.0 g of acetonitrile to form a solution, and 1.21 g of lithium perchlorate was added as a supporting salt, After dissolving uniformly,
The mixture was poured into a Teflon boat, heated at 110 ° C. on a hot plate under an argon atmosphere, and the solvent was evaporated by vacuum to obtain a 0.50 mm thick electrolyte for a secondary battery.

Example 13 The borate ester compound (3) obtained in Production Example 3 (2.0)
To 0 g, 2.00 g of polyethylene oxide (500,000) manufactured by Wako Pure Chemical Industries, Ltd. was mixed, added to 10.0 g of acetonitrile to form a solution, and 1.13 g of lithium perchlorate as a supporting salt was added. After dissolving uniformly,
The mixture was poured into a Teflon boat, heated at 110 ° C. on a hot plate under an argon atmosphere, and the solvent was evaporated by vacuum to obtain a 0.50 mm thick electrolyte for a secondary battery.

Example 14 The boric acid ester compound (4) obtained in Production Example 4 (2.0)
To 0 g, 2.00 g of polyethylene oxide (500,000) manufactured by Wako Pure Chemical Industries, Ltd. was mixed and added to 10.0 g of acetonitrile to form a solution, and 0.61 g of lithium perchlorate was added as a supporting salt, After dissolving uniformly,
The mixture was poured into a Teflon boat, heated at 110 ° C. on a hot plate under an argon atmosphere, and the solvent was evaporated by vacuum to obtain a 0.50 mm thick electrolyte for a secondary battery.

Example 15 The borate ester compound (5) obtained in Production Example 5 (2.0)
To 0 g, 2.00 g of polyethylene oxide (500,000) manufactured by Wako Pure Chemical Industries, Ltd. was mixed and added to 10.0 g of acetonitrile to form a solution, and 1.21 g of lithium perchlorate was added as a supporting salt, After dissolving uniformly,
The mixture was poured into a Teflon boat, heated at 110 ° C. on a hot plate under an argon atmosphere, and the solvent was evaporated by vacuum to obtain a 0.50 mm thick electrolyte for a secondary battery.

Example 16 The borate compound (6) obtained in Production Example 6 (2.0)
To 0 g, 2.00 g of polyethylene oxide (500,000) manufactured by Wako Pure Chemical Industries, Ltd. was mixed and added to 10.0 g of acetonitrile to form a solution, and 1.21 g of lithium perchlorate was added as a supporting salt, After dissolving uniformly,
The mixture was poured into a Teflon boat, heated at 110 ° C. on a hot plate under an argon atmosphere, and the solvent was evaporated by vacuum to obtain a 0.50 mm thick electrolyte for a secondary battery.

Comparative Example 1 Blenmer PDE-400 (polyethylene glycol (400) dimethacrylate) manufactured by NOF Corporation 4.00
g, 2.19 g of LiTFSI was added as a supporting salt,
After uniformly dissolving, the mixture was poured into a Teflon boat, thermally polymerized at 110 ° C. on a hot plate under an argon atmosphere, and dried under vacuum to obtain a 0.50 mm-thick secondary battery electrolyte.

Comparative Example 2 Polyethylene glycol # 4000 manufactured by NOF Corporation
(Molecular weight 4000) to 4.00 g of LiT as a supporting salt
After adding 3.26 g of FSI and dissolving uniformly, pour into a Teflon boat, heat at 110 ° C. on a hot plate under an argon atmosphere, and volatilize the solvent by vacuum to obtain a 0.50 mm thick secondary. An electrolyte for a battery was obtained.

Comparative Example 3 Poly (acrylonitrile / methacrylic acid = 93/7 parts by weight) (molecular weight 200000, random copolymer)
00 g in dimethylformamide 10.0 g,
3.73 g of lithium perchlorate was added as a supporting salt, and after uniformly dissolving, poured into a Teflon boat and heated at 110 ° C. on a hot plate under an argon atmosphere,
The solvent for the secondary battery having a thickness of 0.50 mm was obtained by volatilizing the solvent by vacuum.

Comparative Example 4 Blemmer PME-400 (methoxypolyethylene glycol (400) methacrylate) manufactured by NOF Corporation
4.00 g of lithium perchlorate as a supporting salt in 0.9 g
After adding 8 g and dissolving uniformly, the mixture was poured into a Teflon boat and placed on a hot plate under an argon atmosphere.
Thermal polymerization is carried out at 0 ° C., and dried by vacuum to obtain a thickness of 0.1 mm.
A 50 mm electrolyte for a secondary battery was obtained.

Comparative Example 5 Blenmer PDE-400 (polyethylene glycol (400) dimethacrylate) manufactured by NOF Corporation 4.00
To 0.8 g, add 0.81 g of lithium perchlorate as a supporting salt, uniformly dissolve, pour into a Teflon boat, thermally polymerize at 110 ° C on a hot plate under an argon atmosphere, and dry under vacuum. 0.50m thick
m of secondary battery electrolyte was obtained.

The polymer electrolytes obtained in Examples and Comparative Examples were evaluated for film formability and ionic conductivity by the following methods. (1) Film formability ○: A film can be obtained without any problem ×: Poor curing or film formation impossible (2) Ionic conductivity A polymer electrolyte is sandwiched between stainless steel electrodes, and the temperature is changed under an argon atmosphere to change each temperature. An AC complex impedance measurement at a temperature was performed, and the diameter of the semicircle of the bulk resistance component in the obtained plot on a complex plane (Cole-Cole plot) was determined as ionic conductivity.

Table 1 shows the composition of the borate compound obtained in the Production Example, and Table 2 shows the composition of the borate compound and the organic polymer compound and the type of the ionic compound in Examples and Comparative Examples. Table 3 shows the evaluation results of the ionic conductivity at 25 ° C., 50 ° C., and 80 ° C.

[0062]

[Table 1]

* [/] Indicates random addition.

[0064]

[Table 2]

* MAA represents methacrylic acid or a methacrylic acid residue, and EO represents an oxyethylene group. * 1: 200,000 molecular weight, random copolymer

[0066]

[Table 3]

In the comparative example, a film satisfying both the film formability and the ion conductivity was not obtained, whereas the polymer electrolyte of the present invention provided good film formability and high ion conductivity. It was confirmed that the degree could be obtained.

Example 17 A secondary battery using the secondary battery electrolyte of the present invention was prepared.
The charge / discharge test was evaluated by the following method. 75 parts by weight of LiMn ₂ O ₄ powder as a positive electrode active material, 5 parts by weight of polyvinylidene fluoride powder as a binder polymer, and 20 parts by weight of carbon powder as a conductive material are well kneaded, and a thickness of 0 is formed on an aluminum foil by hot pressing. A positive electrode material having a diameter of 10 mm and a diameter of 10 mm was obtained. A lithium metal foil having a thickness of about 0.08 mm and a diameter of 10 mm was used as the negative electrode material as an alkali metal ion storage material. The electrolyte for a secondary battery of Example 4 was 10 mm in diameter.
, And sandwiched between the above-described positive electrode material and negative electrode material, and further sandwiched between stainless steel electrodes to obtain a secondary battery.

Comparative Example 6 LIPASTE EDEC (manufactured by Toyama Pharmaceutical Co., Ltd., mixed solution of ethylene carbonate / diethyl carbonate (1/1 volume ratio), indicator salt: lithium perchlorate, indicator salt concentration: 1 mol / l) was electrolyzed. Liquid. Filling the above electrolyte solution into a closed cell sandwiching a 0.50 mm thick porous polytetrafluoroethylene separator,
A secondary battery was obtained by sandwiching between the above-described positive electrode material and negative electrode material, and further between stainless steel electrodes.

After charging each secondary battery at 50 ° C. at a current density of 155 mA / m ^{2 to} 4.35 V, charging and discharging at a current density of 155 mA / m ^{2 to} 3.50 V were repeated 30 cycles. First cycle of each battery, 1
The discharge capacity per 1 kg of the positive electrode at the 5th cycle and the 30th cycle was determined. Table 4 shows the evaluation results of the charge / discharge test.

[0071]

[Table 4]

In the secondary battery using the polymer electrolyte of the present invention, although the initial discharge capacity was slightly inferior due to the interfacial resistance component with the electrode material, Comparative Example 6 was a liquid, and the capacity decreased with the cycle. , But excellent cycle characteristics were confirmed.

[0073]

The electrolyte for a secondary battery, which is a polymer electrolyte of the present invention, has high ionic conductivity and is excellent in safety, and therefore is useful as a material for electrochemical devices such as batteries. When the electrolyte is used, a secondary battery device having high ionic conductivity over a wide temperature range and excellent in cycle characteristics and safety can be obtained.

Claims (5)

[Claims] 1. An electrolyte for a secondary battery comprising an ionic compound and an organic polymer compound, wherein the organic polymer compound is obtained by esterifying a compound represented by the formula (1) with boric acid or boric anhydride. An electrolyte for a secondary battery, comprising a boric acid ester compound. Z ¹ -[(A ¹ O) ₁ -H] _a (1) (Z ¹ is a residue of a compound having ¹ to 6 hydroxyl groups, A ¹ O is one kind of an oxyalkylene group having 2 to 4 carbon atoms) Or a mixture of two or more, wherein l = 0 to 600, a = 1 to 6, and la = 0 to 600.) 2. The electrolyte for a secondary battery according to claim 1, wherein the organic polymer compound comprises a borate compound and a polymer of the compound represented by the formula (2). Z ² -[(A ² O) _m -R ¹ ] _b (2) (Z ² is a residue or a hydroxyl group of a compound having 1 to 4 hydroxyl groups, and A ² O is an oxy group having 2 to 4 carbon atoms. A mixture of one or more alkylene groups, m = 0 to 15;
0, b = 1 to 4 and mb = 0 to 300,
R ¹ is a hydrogen atom or a group represented by the formula (3). ) (R ² and R ³ are a hydrogen atom or a methyl group.) 3. The organic polymer compound comprising a borate compound and a compound represented by the formula (4).
The electrolyte for a secondary battery as described in the above. Z ³ -[(A ³ O) _n -H] _c (4) (Z ³ is a residue of a compound having 1 to 6 hydroxyl groups, A ³ O is one kind of an oxyalkylene group having 2 to 4 carbon atoms) Or a mixture of two or more, n = 100 to 150,000, c =
1 to 6 and nc = 100 to 150,000. ) 4. The electrolyte for a secondary battery according to claim 1, wherein the ionic compound is an alkali metal salt. 5. A secondary battery using the electrolyte for a secondary battery according to claim 1, 2, 3, or 4.