JPH04211412A - Production of polymer solid electrolyte - Google Patents

Abstract

PURPOSE:To produce an ion-conductive polymer useful for lithium electric battery, plastic electric battery, large-volume condenser, electrochromic display and other wholly solidifying use. CONSTITUTION:The ion-conductive polymer in present invention is produced by mixing the first liquid obtained by dissolving a radical polymerization initiation accelerator in a polyether-based macromonomer with the second liquid obtained by dissolving a radical polymerization initiator in a both ends- alkyletherified polyether oligomer and/or organic solvent. An alkali metal salt and/or ammonium salt are added to at least either one of both liquids.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION This invention relates to ionically conductive polymers, namely solid polymer electrolytes.

0002

[Prior art and problems to be solved by the invention] In recent years, compared to inorganic solid electrolytes, it has been found that 1) it is moldable and can be easily formed into a thin film over a large area, and 2) it is flexible and has good adhesion to electrodes. Progress is being made in the development of organic polymer solid electrolytes, which have features such as superior properties.

[0003] As a solid polymer electrolyte, M. B. A
A mixture of polyethylene oxide and an alkali metal salt was proposed by Rmand et al. (”Fast Ion
Transport in Solids” Pag
e131, 1979 North Holland
Publishing Co. See publication. )

[0004] However, the method for manufacturing the solid electrolyte is to form a film by a so-called casting method, in which the solid electrolyte is dissolved in a solvent and then cast onto a molding surface, and then the solvent is dried and removed. Therefore, the processing operation is complicated,
The resulting film has a conductivity of 10-6 S/ at room temperature.
cm or less, and the adhesion with the electrode was also not satisfactory, and improvement was desired.

[0005] Other examples include Japanese Patent Application Laid-Open No. 1986-62-
A method of crosslinking by the reaction of trifunctional polyethylene glycol with a diisocyanate derivative in Japanese Patent Laid-Open No. 62-285954 has been proposed, and a method of crosslinking by a polymerization reaction of polyethylene glycol diacrylate in JP-A No. 62-285954 has been proposed. Therefore, a step of drying and removing the solvent is essential, and further improvements are needed in terms of balance with ionic conductivity, adhesion with electrodes, and other factors.

On the other hand, the ionic conductivity of solid polymer electrolytes generally decreases significantly in the low temperature range below room temperature, and there has been a strong demand for improvement in this respect as well.

[0007]

[Means for Solving the Problems] In order to overcome these obstacles, the inventors have focused on research and experiments and have discovered that a solid polymer electrolyte can be produced without using any solvent. In addition to this, the ionic conductivity of the polymer solid electrolyte obtained was 10-6 S/ at 0°C.
It was also discovered that the adhesiveness of these materials can exceed cm 2 and that they can have good adhesion to electrodes, and fortunately, this invention has been completed.

[0008] The present invention is a method for producing a solid polymer electrolyte, which includes mixing the following solutions A and B containing an alkali metal salt and/or an ammonium salt in at least one of the solutions. .

Solution A: A solution in which a radical polymerization initiation accelerator is dissolved in the compound represented by the general formula (1).

[Formula 5] (wherein, R1 is hydrogen or an alkyl group having 1 to 5 carbon atoms, R2 is an alkyl group having 1 to 5 carbon atoms, and m represents an integer of 2≦m≦30.)
Solution B: Compound represented by general formula (2)

embedded image (wherein R3 and R5 are alkyl groups having 1 to 5 carbon atoms, R4 is hydrogen or an alkyl group having 1 to 3 carbon atoms, and n is an integer of 2≦n≦30) and/ or a compound represented by general formula (3)

[C7]

[0010] (wherein,

[Chemical formula 8], R6 is a hydrocarbon group having 1 to 6 carbon atoms,
R7 and R8 are simple bonds or single prime numbers 1 to
3 is a divalent hydrocarbon group, R9 represents a hydrocarbon group having 1 to 6 carbon atoms or a cyano group; R6 and R9
may be linked to each other to form a ring, p , q and r are each 0 or 1, and p + q + r > 0, except when R4 is a cyano group. ) in which a radical polymerization initiator is dissolved.

[0011] The present invention will be explained in detail below.

[0012] The production method of the present invention is characterized in that both liquids A and B contain an alkali metal salt and/or ammonium salt in at least one of the liquids, that is, A has the general formula (
1) A solution in which a radical polymerization initiation accelerator is dissolved in a compound represented by formula (2), and B is a solution in which a radical polymerization initiation accelerator is dissolved in a compound represented by general formula (2) and/or a compound represented by general formula (3). This is a solution in which an initiator is dissolved, and in this method, a solid polymer electrolyte is produced by mixing these two solutions.

First, liquid A will be explained.

The general formula used in this invention is (1
As is clear from its structural formula, the compound represented by ) is a polyether macromonomer having an oxyethylene unit in its side chain, and exhibits a liquid phase at room temperature.

In the formula, R1 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, preferably 1 to 3 carbon atoms, such as a hydrogen atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a pentyl group, etc. Preferred are a hydrogen atom, a methyl group, an ethyl group, and the like.

R2 is an alkyl group having 1 to 5 carbon atoms, preferably 1 to 3 carbon atoms, and includes a hydrogen atom, a methyl group,
Examples include ethyl group, propyl group, isopropyl group, butyl group, pentyl group, etc., and preferably methyl group, ethyl group, propyl group, etc.

Further, the number of oxyethylene units in the compound represented by general formula (1), that is, the value of m is
2≦m≦30, preferably 2≦m≦20
, more preferably 3≦m≦15.

Specifically, the compound represented by the general formula (1) includes methoxypolyethylene glycol methacrylate, ethoxypolyethylene glycol methacrylate, methoxypolyethylene glycol acrylate, and ethoxypolyethylene glycol having the number of oxyethylene units within the above range. Examples include acrylate.

The radical polymerization initiation accelerator used in this invention is soluble in the compound of general formula (1), and is not particularly limited as long as it has the effect of reducing the radical polymerization initiator described below. Examples include various anilines, amines, reducing transition metal compounds, sulfur-containing compounds, and the like. Specifically, anilines such as aniline, N,N-dimethylaniline, N,N-diethylaniline, and N,N-dibutylaniline;
triethylamine, diethylamine, piperidine, 1,
Amines such as 2-diaminoethane, FeCl2・n
Fe(2) such as H2O, FeS, FeSO4
Salt, CoCl2, CoBr2, CoSO4, Co
S etc. Co(2) salt, MoCl5 etc. Mo(
5) Salts, thiols such as methanethiol, ethanethiol, benzenethiol, phenylmethanethiol, 1,4-butanedithiol, p-mercaptobenzoic acid, thiol salts such as potassium ethanethiolate, sodium ethanethiolate, diethyl sulfide, ethylthiobenzene , 1,2-bis(methylthio)ethane, 4,4'-
Sulfides such as thiodibenzoic acid, 3-(methylthio)propanol, bis[(ethylthio)methyl] sulfide, thiacyclooctane, 1,2-dithiane, 2,3-dihydro-1,4-dithiaphthalene, or various Examples include sulfites and sulfinic acids, preferably aniline, N,N-dimethylaniline, N,N-diethylaniline, triethylamine, FeSO4,
Examples include FeCl2.nH2O, ethanethiol, benzenethiol, sodium ethanethiolate, and diethyl sulfide.

Liquid A has these radical polymerization initiation accelerators dissolved in the compound represented by the general formula (1), and the concentration of the radical polymerization initiation accelerator in Liquid A is 0. 01-10 wt. Within the range of 0.05
~5 wt. It is preferably within the range of %.

Furthermore, it is preferable to add a polyether compound having acryloyl groups at both ends to liquid A, and the amount of addition is 100% of the compound of general formula (1).
It is usually 50 parts by weight or less, preferably 1 to 50 parts by weight, and more preferably 2 to 30 parts by weight. Moreover, as these polyether compounds, for example,
Compound of general formula (4)

embedded image (wherein, R1 and R2 are an alkyl group having 1 to 5 carbon atoms, preferably 1 to 3 carbon atoms, or a hydrogen atom, R1 and R2 may be the same or different, and p is 4 to 30, preferably 5 to 20), and particularly suitable substances include compounds having an acrylic group or a methacrylic group at both ends.

Next, liquid B will be explained.

As is clear from its structural formula, the compound represented by the general formula (2) used in the method of this invention is a polyether oligomer in which both ends are alkyl etherified, and at room temperature It is in a liquid phase state.

R4 in the formula is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and examples of the oxyalkylene unit include oxyethylene unit, oxypropylene unit, oxybutylene unit, etc. More than one type of oxyalkylene unit may coexist.

The number of these oxyalkylene units, ie, n is 2≦n≦30, preferably 2≦n
≦20, more preferably 3≦n≦15. In addition, R3 and R5 in the formula have 1 to 5 carbon atoms.
, preferably 1 to 3 alkyl groups, such as methyl group, ethyl group, propyl group, isopropyl group, etc. Specifically, these compounds include:
Dimethoxypolyethylene glycol, diethoxypolyethylene glycol, dipropoxypolyethylene glycol, dimethoxypolypropylene glycol, diethoxypolypropylene glycol, dimethoxypolyethylene
Examples include propylene glycol, dimethoxypolyethylene-butylene glycol, and others.

Compound represented by general formula (3)

embedded image is a so-called organic nonaqueous solvent that is in a liquid phase at room temperature. In the formula, R6 is a hydrocarbon group having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, and is a methyl group,
Examples include alkyl groups such as propyl group, isopropyl group, butyl group, sec-butyl group, tert-butyl group, isobutyl group, and bentyl group, and aryl groups such as phenyl group. R7 and R8 are a simple bond or a divalent hydrocarbon group having 1 to 3 carbon atoms, and include alkylene groups such as methylene group, ethylene group, trimethylene group, and propylene group, and arylene groups such as phenylene group. can. R9 is a cyano group,
Alternatively, it has 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms, and this hydrocarbon group is the same as R6. In addition, R6 and R9 may be connected to each other to form a ring, and in this case, R6 and R9 may each constitute a part of a divalent hydrocarbon group in addition to the hydrocarbon groups exemplified above. It is. Such divalent hydrocarbon groups include those having 2 to 6 carbon atoms, such as ethylene group,
Examples include alkylene groups such as trimethylene group, propylene group, and tetramethylene group. p, q and r are each 0 or 1, and p + q + r > 0, except when R4 is a cyano group. Also,

[Chemical formula 11]

[0027] Specifically, the compound represented by the general formula (3) includes ethylene carbonate, propylene carbonate, γ-butyrolactone,
Examples include dimethoxyethane, acetonitrile, dimethyl sulfoxide, dioxolane, and sulfolane.

General formula (3) used in this invention
The compound represented by can be used regardless of its dielectric constant value, but those having a dielectric constant of 30 or more are particularly preferred.

The radical polymerization initiator used in the method of this invention is soluble in the compound represented by general formula (2) and/or the compound represented by general formula (3), and does not easily generate radicals. If there is, organic peroxides are exemplified as suitable substances, although they are not particularly limited. Examples of organic peroxides include dialkyl peroxides, diacyl peroxides, peroxy esters,
Hydroperoxide, ketone peroxide, etc. Specifically, benzoyl peroxide, 2
, 4-dichlorobenzoyl peroxide, lauroyl peroxide, dicumyl peroxide, methyl ethyl peroxide, cyclohexanone peroxide, cumene hydroperoxide, t-butyl peroxy acetate,
Examples include t-butyl peroxyisobutyrate, t-butyl peroxypivalate, acetyl peroxide, diisopropyl peroxy carbonate, paramethane hydroperoxide, diisopropylbenzene hydroperoxide, propionyl peroxide, etc. Preferably benzoyl peroxide, t-butylperoxyisobutyrate, acetyl peroxide,
Examples include methyl ethyl peroxide.

Liquid B has these radical polymerization initiators dissolved in the compound of general formula (2) and/or the compound of general formula (3), and the radical polymerization initiator in liquid B is The concentration of the agent is 0.01 to 10 wt. % within the range of 0.05 to 5 wt. % range is more preferable.

Furthermore, the compound of general formula (2) and the compound of general formula (3)
) When using the compound of general formula (
The weight ratio of the compound 3) is 99:1 to 1:
99, preferably 90:10
It is desirable that the ratio is within the range of ~10:90.

[0032] In the present invention, an alkali metal salt and/or an ammonium salt is further contained in the above-mentioned liquid A and/or liquid B. As alkali metal salts and ammonium salts, general formula (1) is used.
The alkali metal salt is not particularly limited as long as it is soluble in the compound, general formula (2) compound, or general formula (3) compound, and examples of the alkali metal salt include lithium perchlorate, sodium perchlorate, and perchloric acid. Alkali metal salts of perchlorate such as potassium, alkali metal salts of tetrafluoroboric acid such as lithium tetrafluoroborate, sodium tetrafluoroborate, and potassium tetrafluoroborate, alkali metal salts of hexafluorophosphate such as lithium hexafluorophosphate and potassium hexafluorophosphate, and alkali metal trifluoroacetates such as lithium trifluoroacetate. Examples include alkali metal salts of trifluoromethanesulfonate such as lithium trifluoromethanesulfonate. Examples of ammonium salts include tetraisopropylammonium perchlorate and tetra-n- perchlorate.
Perchloric acid quaternary ammonium salts such as butylammonium,
Tetra n-butylammonium tetrafluoroborate,
Hexafluorophosphate tetra n- Butylammonium, etc. Tetrafluoroboric acid or hexafluorophosphate quaternary ammonium salt, trifluoromethanesulfonic acid tetra n-
Examples include trifluoromethanesulfonic acid quaternary ammonium salts such as butylammonium.

The content of the alkali metal salt or ammonium salt is 1 part by weight per 100 parts by weight of the total amount of liquids A and B.
It is preferably within the range of 30 to 30 parts by weight, and 3 to 20 parts by weight.
It is more preferably within the range of parts by weight.

In the method for producing a solid polymer electrolyte of the present invention, liquids A and B are mixed and then cured, and at this time, the mixing ratio of liquids A and B is set according to the present invention. There is no particular limitation as long as the purpose of
Usually, the weight ratio of liquid A to liquid B is 1:10 to 10.
: Within the range of 1 : 5 to 5 : 1
More preferably, it is within the range of . If there is too much A liquid, the ionic conductivity of the produced polymer solid electrolyte at low temperature tends to decrease, and if B liquid is too much, the strength of the produced polymer solid electrolyte film tends to deteriorate. The temperature when mixing liquid A and liquid B is usually in the range of 0 to 50°C, preferably in the range of 5 to 40°C. Of course, handling operations for these two liquids must be carried out under an inert gas atmosphere such as N2Ar. In the method of this invention, curing starts at the same time as liquid A and liquid B are simply mixed, and no other special treatment is required, but the curing temperature is usually 0 to 50°C, preferably is within the range of 5 to 40°C, and
The curing time is also appropriately determined depending on various conditions such as the amount of each component to be charged and the temperature, but from the viewpoint of productivity, it is usually 5 minutes to 5 hours, preferably 10 minutes to 3 hours.
Preferably within the time range. In addition, in this invention, an organic non-aqueous solvent such as propylene carbonate, ethylene carbonate, dimethoxyethane, dimethyl sulfoxide, etc. may be allowed to coexist in liquid A as long as it does not impair the purpose of this invention. The amount is typically 80 wt. of the total amount. % or less, preferably 1 to 80 wt. %, more preferably 5 to 6
0 wt. It is preferably within the range of %. According to the method of the present invention, the mixture can be cured at low temperatures simply by mixing the A and B solutions, which is extremely advantageous as a process for producing solid polymer electrolytes. That is, in the conventional casting method using a solvent, a step of drying and removing the solvent was essential, but in the method of the present invention, there is virtually no solvent to be removed, so the solvent ejection step is naturally unnecessary. Furthermore, if desired, the film can be formed directly on the electrode, and the adhesion to the electrode is also good. In producing the solid polymer electrolyte of the present invention, liquids A and B may be mixed in the presence of a porous synthetic resin film such as porous polypropylene or polypropylene nonwoven fabric, which are commonly used in battery separators. This is preferably carried out.

[0035]

[Examples] The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples in any way.

Example 1

[0037] Methoxypolyethylene glycol monomethacrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd. M90G) [number of oxyethylene units: 9] 10.0 g, N, N-
0.1 g of dimethylaniline was added and this was used as Solution A. Add 0.83 g of lithium perchlorate to 10.0 g of polyethylene glycol dimethyl ether (Eunox DM 200 manufactured by Lion) [approximately 4 oxyethylene units], add 0.06 g of benzoyl peroxide, and add this to liquid B. And so. These AB
The two liquids were mixed at a 1:1 weight ratio at room temperature of 25° C. and immediately cast on a polypropylene plate at room temperature. After 15 minutes, a gel-like film with no bleeding was obtained. The ionic conductivity of this membrane was measured by the AC impedance method. At 3.0 °C, the measured value is 2.3×
It was 10-5 S/cm.

Example 2

[0039] 0.1 g of triethylamine was added to 10.0 g of methoxypolyethylene glycol monomethacrylate similar to Example 1 to prepare a solution A. Polyethylene glycol dimethyl ether similar to Example 1 5
．． 0.0 g of propylene carbonate was mixed with 0.83 g of lithium perchlorate, and further 0.06 g of cumene hydroperoxide was added thereto to prepare a B solution. These two liquids were mixed at room temperature in a weight ratio of 1:1 and immediately cast on a polypropylene plate at room temperature, and a gel-like film was obtained after 60 minutes. When its ionic conductivity was measured by the same method as in Example 1, it was found to be 5.1 x 10-5 S/cm at 0°C.

Example 3

0.1 g of ethanethiol was added to a mixture of 5.0 g of methoxypolyethylene glycol monomethacrylate and methoxypolyethylene glycol dimethacrylate (manufactured by Shin Nakamura Chemical Industries, Ltd. 9G) [oxyethylene unit number: 9] as in Example 1. This was designated as Solution A. To 10.0 g of the same polyethylene glycol dimethyl ether as in Example 1, 0.83 g of lithium perchlorate was added, and further benzoyl peroxide was added.
0.06g was added and this was made into B liquid. These two liquids were mixed at a weight ratio of 1:1 and immediately cast onto a polypropylene plate. After 30 minutes, a membrane even tougher than that of Example 1 was obtained. The ionic conductivity of this membrane was measured in the same manner as in Example 1 and found to be 1.0 × 10-5 S/cm at 0°C.
Met.

Comparative example

[0043] In a mixture of 10.0 g of methoxypolyethylene glycol monomethacrylate similar to Example 1 and 10 g of polyethylene glycol dimethyl ether similar to Example 1, 0.83 g of lithium perchlorate was dissolved, and further 0.83 g of lithium perchlorate was dissolved. Added .06g. Although this liquid was cast on the surface of a polypropylene plate, it was impossible to form a film at room temperature.

Example 4

The A and B solutions obtained in Example 2 were mixed at a weight ratio of 1:1, and then impregnated into a polypropylene nonwoven fabric having a thickness of 50 microns at room temperature. After sufficient impregnation, the remaining liquid on the surface of the nonwoven fabric was wiped off, and then left for 45 minutes. Thereafter, the ionic conductivity of the obtained membrane material was measured by the same method as in Example 1, and it was found to be 3.2 x 10-5 S/ at 0°C.
It was cm.

Example 5

0.1 g of N,N-dimethylaniline was added to 10 g of methoxypolyethylene glycol monomethacrylate (M90G, manufactured by Shin-Nakamura Chemical Industries, Ltd., 9 oxyethylene units) to prepare a solution A. 0.85 g of lithium perchlorate was added to 10.0 g of propylene carbonate, and 0.07 g of benzoyl peroxide was further added to prepare a B solution. This A, B
Both solutions were mixed at a weight ratio of 1:1 at room temperature of 25° C., and immediately cast on the surface of a polypropylene plate at room temperature. After 15 minutes, a gel-like film with no bleed was obtained. When ionic conductivity was measured using the AC impedance method, it was found to be 4 x 10-4 at 0°C.
It was S/cm.

Example 6

[0049] Methoxypolyethylene glycol monomethacrylate (M90G manufactured by Shin-Nakamura Chemical Industries) [Number of oxyethylene units: 9] 10.0 g, N, N
- Add 0.1g of dimethylaniline and mix it with A
It was made into a liquid. Add 0.75 g of lithium perchlorate to 10.0 g of sulfolane and add 0.0 g of benzoyl peroxide.
6g was added and this was used as Solution B. Both A and B liquids
The mixtures were mixed in a weight ratio of 1:1 at room temperature of 25° C., and immediately cast on a polypropylene plate at room temperature.
After 15 minutes, a gel-like film with no bleed was obtained. When its ionic conductivity was measured by the AC impedance method, it was 7.8 x 10-5 S/cm at 0°C.
Met.

Example 7

[0051] Methoxypolyethylene glycol monomethacrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd. M90G) [Number of oxyethylene units: 9] 10.0 g, N, N
- Add 0.1g of dimethylaniline and mix it with A
It was made into a liquid. 0.77 g of lithium perchlorate was added to 10.0 g of a mixture of propylene carbonate and ethylene carbonate in a weight ratio of 4:1, and further 0.05 g of benzoyl peroxide was added to obtain a B solution. This A, B
Both solutions were mixed at a weight ratio of 1:1 at room temperature of 25° C., and immediately cast on the surface of a polypropylene plate at room temperature. After 15 minutes, a gel-like film with no bleed was obtained. When the ionic conductivity was measured by the AC impedance method, it was 7 x 10-4 S/cm at 0°C.
Met.

[0052]

Effects of the Invention The method for producing a solid polymer electrolyte according to the present invention is extremely advantageous as a production process because it only requires mixing two liquids at room temperature. Due to its high conductivity of 10-6 S/cm or more at 0°C and good adhesion with electrodes, it is suitable for all-solid-state applications such as lithium batteries, plastic batteries, large-capacity capacitors, and electrochromic displays. This product can be applied to a wide range of applications as a solid-state ionics device.

Claims (1)

[Claims] 1. A polymeric solid comprising a mixture of the following liquids A and B, at least one of which contains an alkali metal salt and/or an ammonium salt. Method of manufacturing electrolyte. Solution A: A solution in which a radical polymerization initiation accelerator is dissolved in the compound represented by the general formula (1) [Formula 1] (wherein, R 1 is hydrogen or an alkyl group having 1 to 5 carbon atoms, and R 2 is carbon It is an alkyl group of numbers 1 to 5, and m represents an integer of 2≦m≦30.)
Liquid B: a compound represented by the general formula (2) [Formula 2] (wherein, R 3 and R 5 are an alkyl group having 1 to 5 carbon atoms, and R 4 is hydrogen or an alkyl group having 1 to 3 carbon atoms. (where n represents an integer of 2≦n≦30), and/or a compound represented by the general formula (3) [Chemical formula 3] (wherein, R6 represents a carbon number of 1 to 6) hydrocarbon group,
R7 and R8 are a simple bond or have a carbon number of 1 to
3 is a divalent hydrocarbon group, R9 represents a hydrocarbon group having 1 to 6 carbon atoms or a cyano group, R6 and R
9 may be interconnected to form a ring, p , q
and r are each 0 or 1, and p + q + r>0, except when R4 is a cyano group. )
A solution in which a radical polymerization initiator is dissolved.