JPH04331220A - Production of solid state polyelectrolyte - Google Patents

Abstract

PURPOSE:To obtain a conductive polymer having excelling adhesion to an electrode and high ionic conductivity by adding a radical polymerization retarder and an alkali to either polyethylene glycol (meth)acrylate in which a radical polymerization initiation accelerator is dissolved or a polyalkylene glycol and mixing both solutions. CONSTITUTION:A solid state polyelectrolyte is obtained by mixing solution A in which a radical polymerization initiation accelerator is dissolved and solution B in which a radical polymerization initiator is dissolved (either solution A or solution B contains a radical polymerization retarder and an alkali metal salt and/or an NH4 salt). Solution A contains a polyethylene glycol acrylate of formula I (wherein R<1> is H or 1-5 C alkyl, R<2> is 1-5 C alkyl, and (m) is in the range of 2<=m<=30), and solution B contains a polyether of formula II (wherein R<3> and R<5> are each 1-5 C alkyl, R<4> is H or 1-3 C alkyl, and (n) is in the range of 2<=n<=30) and/or a polyether of formula III (wherein X is CO, SO2 or SO, and R<6> is a 1-6 C hydrocarbon group or the like).

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 has good formability and can be easily formed into a thin film over a large area, and 2) it has flexibility.
Progress is being made in the development of organic polymer solid electrolytes that have features such as excellent adhesion with electrodes.

[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. However, the method for producing the solid electrolyte involves dissolving the solid electrolyte in a solvent, casting it onto the molding surface, and then drying and removing the solvent, which is the so-called casting method. The operation is complicated, and the conductivity of the obtained film is less than 10-6 S/cm at room temperature, and the adhesion with the electrode is not satisfactory, and improvement thereof has been desired.

[0004] As another example, Japanese Patent Application Laid-Open No. 62-48
A method of crosslinking by the reaction of trifunctional polyethylene glycol and a diisocyanate derivative according to No. 716, and a method of crosslinking by a polymerization reaction of polyethylene glycol diacrylate described in JP-A No. 62-285954 are disclosed, but in both cases a solvent is used. Because of this, dry removal of the solvent is essential, and
Further improvements were needed in terms of balance with ionic conductivity, adhesion with electrodes, and other factors.

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

The present inventors have proposed a method for producing a solid polymer electrolyte of the two-component mixing and curing type that overcomes the above-mentioned drawbacks (Japanese Patent Application No. 2-62685). Since the speed is high, there is a drawback that the time for the film forming operation is restricted, and further improvements have been desired.

[0007]

[Means for Solving the Problems] As a result of research conducted by the inventors to resolve these obstacles, the initial curing speed after mixing AB and AB liquids was controlled without using any solvent to be removed. It was discovered that a polymer solid electrolyte can be produced by the following method, and the ionic conductivity of the obtained polymer solid electrolyte is 10-6 S/c at 0°C.
The present invention was completed based on the discovery that the adhesiveness exceeds m and that the adhesion to the electrode is good.

[0008] The present invention provides at least the following liquid A or B.
A production method characterized in that a solid polymer electrolyte is obtained by mixing liquids A and B, one of which contains a radical polymerization retarder, an alkali metal salt and/or an ammonium salt. be.

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

00
10]

[Formula 4] (In the formula, 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 is an integer of 2≦m≦30.) Solution B is a compound represented by general formula (2)

[0011]

[Formula 5] (wherein R3 and R5 are an alkyl group 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)

0012

[Chemical formula 6], R6 is a hydrocarbon group having 1 to 6 carbon atoms, R7
and R8 is a simple bond or a single prime number 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 connected to each other to form a ring, and p, q and
r is 0 or 1, and p+q+r>0 except when R4 is a cyano group. ) is a solution in which a radical polymerization initiator is dissolved.

The present invention will be explained in detail below.

[0014] The present invention provides a radical polymerization retarder, an alkali metal salt and/or an ammonium salt at least
or both liquids A and B contained in one liquid, that is, a solution of a radical polymerization initiation accelerator dissolved in a compound of general formula (1) which is liquid A, and a solution of the general formula (1) which is liquid B. This is a method for producing a polymer solid electrolyte by mixing the compound of 2) and/or the compound of general formula (3) with a solution in which a radical polymerization initiator is dissolved.

First, liquid A will be explained.

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

[0017] In the formula, R1 is a hydrogen atom or the number of carbon atoms
1 to 5, preferably 1 to 3 alkyl groups, such as a hydrogen atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a pentyl group, and preferably a hydrogen atom, a methyl group, and an ethyl group. etc.

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.

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

The radical polymerization initiation accelerator used in the present invention is not particularly limited as long as it is soluble in the compound of general formula (1) and has the effect of reducing the radical polymerization initiator described below. Examples include various anilines, amines, reducing transition metal compounds, and sulfur-containing compounds.

Specifically, for example, aniline, N,N-
Dimethylaniline, N,N-diethylaniline, N,N
- Anilines such as dibutylaniline, amines such as triethylamine, diethylamine, piperidine, 1,2-diaminoethane, FeCl2・nH2O, Fe
S, Fe(2) salts such as FeSO4, CoCl2
, CoBr2 , CoSO4 , CoS etc.
(2) Salts, Mo(5) salts such as MoCl5, thiols such as methanethiol, ethanethiol, benzenethiol, phenylmethanethiol, 1,4-butanedithiol, p-mercaptobenzoic acid, potassium ethanethiolate, sodium ethane Thiol salts such as thiolate, diethyl sulfide, ethylthiobenzene, 1,
2-bis(methylthio)ethane, 4,4'-thiodibenzoic acid, 3-(methylthio)propanol, bis[(ethylthio)methyl]sulfide, thiacyclooctane, 1
, 2-dithiane, 2,3-dihydro-1,4-dithiaphthalene, various sulfites, sulfinic acids, etc., preferably aniline, N,
N-dimethylaniline, N,N-diethylaniline, triethylamine, FeSO4, FeCl2・nH2O
, ethanethiol, benzenethiol, sodium ethanethiolate, diethyl sulfide and the like.

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 0.0
5 to 5 wt. It is preferably within the range of %.
In addition, it is also preferable to add a polyether compound having acryloyl groups at both ends to liquid A, and the amount added is usually 50 parts by weight or less per 100 parts by weight of the compound of general formula (1). and preferably 1 to 50 parts by weight, more preferably 2 to 30 parts by weight.
It is desirable that the content be within the range of parts by weight.

Further, as these polyether compounds, for example, compounds of general formula (4)

[0025]

[Formula 7] (wherein, R1 and R2 are an alkyl group having 1 to 5 carbon atoms, preferably 1 to 3 carbon atoms, or a hydrogen atom, and R
1 and R2 may be the same or different,
p is 4-30, preferably 5-20. )
etc. are preferable, and compounds having an acrylic group or a methacrylic group at both ends are particularly exemplified as suitable substances.

Next, liquid B will be explained.

The compound represented by the general formula (2) used in the present invention is:

[0028]

[Image Omitted] As is clear from its structural formula, it is a polyether oligomer in which both ends are alkyl etherified, and it exhibits a liquid state at room temperature.

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.

Number of these oxyalkylene units n
is 2≦n≦30, preferably 2≦n≦20, and more preferably 3≦n≦15. Also, in the formula
R3 and R5 have 1 to 5 carbon atoms, preferably 1 to 3 carbon atoms
Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and an isopropyl group. Specific examples of these compounds include dimethoxypolyethylene glycol, diethoxypolyethylene glycol, dipropoxypolyethylene glycol, dimethoxypolypropylene glycol, diethoxypolypropylene glycol, dimethoxypolyethylene-propylene glycol, dimethoxypolyethylene-butylene glycol, and others.

Compound represented by general formula (3)

0
032]

[Image Omitted] [Image Omitted] is a so-called organic non-aqueous solvent that is liquid at room temperature. R6 in the formula is a hydrocarbon group having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, such as a methyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a tert-butyl group, an isobutyl group, and a benzyl group. Examples include alkyl groups such as groups, aryl groups such as phenyl groups, and the like. 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 or 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 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 is each 0 or 1, and p+q+r>0, except when R4 is a cyano group. This shows that.

Specific examples of the compound represented by the general formula (3) include ethylene carbonate, propylene carbonate, γ-butyrolactone, dimethoxyethane, acetonitrile, dimethyl sulfoxide, dioxolane, and sulfolane.

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

The radical polymerization initiator used in the present invention is soluble in the compound represented by the general formula (2) and/or the compound represented by the general formula (3), and easily generates radicals. Examples of preferred organic peroxides include dialkyl peroxides, diacyl peroxides, peroxy esters, hydroperoxides, ketone peroxides, etc., but are not particularly limited. Specifically, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, dicumyl peroxide, methyl ethyl peroxide, cyclohexanone peroxide, cumene hydroperoxide, t-butyl peroxyacetate, Examples include t-butyl peroxyisobutyrate, t-butyl peroxypivalate, acetyl peroxide, diisopropyl peroxy carbonate, paramethane hydroperoxide, diisopropylbenzene hydroperoxide, propionyl peroxide, etc. Preferred examples include benzoyl peroxide, t-butyl peroxyisobutyrate, acetyl peroxide, and 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 (
It is desirable that the weight ratio of the compound 3) is within the range of 99:1 to 1:99, preferably within the range of 90:10 to 10:90.

In the present invention, the above-mentioned liquid A and/or liquid B contain a radical polymerization retarder and further contain an alkali metal salt and/or an ammonium salt.

The radical polymerization retarder is not particularly limited as long as it has the effect of inhibiting or suppressing the radical polymerization reaction, and preferable examples include 1, 1,
-diphenyl-2-picrylhydrazyl (DPPH),
1,3,5-triphenylfeldazyl (VDZ), 2
,6-di-t-butyl-α-(3,5-di-t-butyl-4
-Oxo-2,5-cyclohexadiene-1-ylidene-P-tolyloxy (Galvinoxyl), 2,2
, 6,6-tetramethyl-4-piperidone-1-oxyl, N-(3-N-oxyanilino-1,3-dimethylbutylidene)-aniline oxide, tri-P-nitrophenylmethyl, or Stable organic radicals such as organic nitrogen radicals, high-valent metal salts such as ferric chloride, ferric bromide, and cupric chloride, quinones such as dichloroquinone and hydroquinone, and organic sulfurs such as dithiobenzoyl disulfide. can be mentioned, but DP
Stable radicals such as PH 2 are particularly preferred.

[0040] In addition, stability in stable radicals means:
In the present invention, it usually means stable in the range of 0 to 50°C, preferably 5 to 40°C.

The amount of the radical polymerization retarder added is usually such that the molar ratio of radical polymerization retarder/radical polymerization initiator is 2.
or less, preferably from 0.001 to 1.5, particularly preferably from 0.01 to 1.0. Of course, two or more types of radical polymerization retarders can also be used.

The alkali metal salt and ammonium salt are not particularly limited as long as they are soluble in the compound of general formula (1), the compound of general formula (2), or the compound of general formula (3). Examples of alkali metal salts include alkali metal perchlorates such as lithium perchlorate, sodium perchlorate, and potassium perchlorate; alkali metal salts of tetrafluoroboric acid such as lithium tetrafluoroborate, sodium tetrafluoroborate, and potassium tetrafluoroborate; Examples include alkali metal salts of hexafluorophosphoric acid such as lithium phosphate and potassium hexafluorophosphate, alkali metal salts of trifluoroacetic acid such as lithium trifluoroacetate, and alkali metal salts of trifluoromethanesulfonic acid such as lithium trifluoromethanesulfonate.

Examples of ammonium salts include quaternary ammonium salts of perchloric acid such as tetraethylammonium perchlorate, tetraisopropylammonium perchlorate, and tetra-n-butylammonium perchlorate, tetraethylammonium tetrafluoroborate, and tetra-n-butyl tetrafluoroborate. Ammonium, quaternary ammonium salts of tetrafluoroboric acid or hexafluorophosphoric acid such as tetraethylammonium hexafluorophosphate, tetran-butylammonium hexafluorophosphate, quaternary ammonium salts of trifluoromethanesulfonic acid such as tetran-butylammonium trifluoromethanesulfonate, etc. Illustrated.

The content of the above alkali metal salt or ammonium salt is preferably in the range of 1 to 30 parts by weight, and 3 to 20 parts by weight, based on 100 parts by weight of the total amount of liquids A and B.
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. Generally, but not limited to, as long as the purpose of
The weight ratio of liquid A to liquid B is within the range of 1:10 to 10:1, and more preferably within the range of 1:5 to 5:1.

[0046] If there is too much liquid A, the ionic conductivity of the polymer solid electrolyte produced at low temperatures tends to decrease, and if liquid B is too large, the strength of the film of the polymer solid electrolyte produced deteriorates and weakens. easy.

[0047] The temperature when mixing liquids A and B is usually in the range of 0 to 50°C, preferably in the range of 5 to 40°C. Of course, the handling operations for these two liquids must be performed using N2,
It is necessary to carry out the process under an inert gas atmosphere such as Ar.

In the method of the present invention, curing starts after a short induction period after liquids A and B are mixed, and no other special treatment is required, but the temperature at the time of curing is The temperature is usually within the range of 0 to 50°C, preferably 5 to 40°C, and the curing time is determined as appropriate depending on various conditions such as the amount of each component and the temperature, but depending on the productivity. From this point of view, usually 5 minutes to 5 hours, preferably
It is desirable that the time be within the range of 10 minutes to 3 hours.

[0049] In the present invention, an organic non-aqueous solvent such as propylene carbonate, ethylene carbonate, dimethoxyethane, dimethyl sulfoxide, etc. may be present in the liquid A as long as it does not impair the purpose of the present invention. The coexisting amount is usually 80wt. of the total amount. % or less, preferably 1 to 80 wt. %, more preferably 5 to 60 wt. It is preferably within the range of %.

According to the method of the present invention, by simply mixing liquids A and B, the mixture can be cured at a low temperature, so it is a simple process and extremely advantageous as a method for producing a solid polymer electrolyte. It is something.

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, since there is substantially no solvent to be removed, the solvent ejection step is not necessary. Naturally, this is not necessary, and if desired, the film can be formed directly on the electrode, resulting in good adhesion to the electrode. In producing the solid polymer electrolyte of the present invention, liquids A and B may be mixed together in the coexistence 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.

[0052]

[Examples] The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these. (Example 1) Methoxypolyethylene glycol monomethacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd. M 90 G
, Oxyethylene unit number: 9) 10ml,
10 mg of N,N-dimethylaniline was added to make this solution A.

[0053] 10 ml of propylene carbonate,
0.75 g of lithium perchlorate and 0.05 g of benzoyl peroxide were added, and further 3 mg of 1,1-diphenyl-2-picrylhydrazyl (DPPH) was added to form a B solution.

[0054] These two solutions A and B were mixed at 25°C in a ratio of 2:1.
When mixed at a weight ratio of . The ionic conductivity of this membrane was measured using the AC impedance method and was found to be 3.3 x 10-3 s/cm at room temperature.
Met. Since there was an induction period, it was possible to fabricate the solid polymer electrolyte extremely easily. (Comparative Example 1) In Example 1, the same operation as in Example 2 was performed except that DPPH was not added. Immediately after mixing the two liquids A and B, the viscosity started to increase and curing was delayed. It was completed in 25 minutes. The ionic conductivity was 2.8 x 10-3 s/cm at room temperature. (Example 2) In Example 1, polyethylene glycol dimethyl ether (Eunox DM manufactured by Lion Corporation) was used instead of 10 ml of propylene carbonate.
200, Number of oxyethylene units: Approx. 4) 10g
The same operation as in Example 1 was performed except that .

When the two solutions A and B were mixed at a weight ratio of 1:1, an induction period of 30 minutes was observed, after which the viscosity began to increase, and after 90 minutes, curing was completed and a gel-like film was obtained. . When the ionic conductivity of this membrane was measured using the AC impedance method, it was found to be 1.5 x 10-3 at room temperature.
s/cm. (Example 3) In Example 1, lithium perchlorate 0
．． Except that 0.92g of tetraethylammonium perchlorate was added to Solution B instead of 75g.
The same operation as in Example 1 was performed.

When the two solutions A and B were mixed at a weight ratio of 1:1, an induction period of 35 minutes was observed, after which the viscosity began to increase, and after 100 minutes, curing was completed and a gel-like film was obtained. Ta. The ionic conductivity of this membrane was measured using the AC impedance method and was found to be 1.2 x 10-3 at room temperature.
s/cm. (Example 4) 20 mg of triethylamine and 5 mg of 1,3,5-triphenylfeldazyl (VDZ) were added to 10.0 g of methoxypolyethylene glycol monomethacrylate similar to Example 1, and this was used as Solution A.

To a mixture of 5.0 g of polyethylene glycol dimethyl ether and 50 g of propylene carbonate, 0.80 g of lithium perchlorate was added, and further 0.06 g of cumene hydroperoxide was added.
was added, and this was designated as Solution B.

[0058] These two solutions A and B were mixed in a ratio of 1:1 at 25°C.
When they were mixed at a weight ratio of , the viscosity did not increase for the first 25 minutes, indicating an induction period, but then the viscosity began to increase, and after 105 minutes, curing was completed and a gel-like film was obtained. When the ionic conductivity of this membrane was measured using the AC impedance method, it was found to be 2.1 x 10-3 at room temperature.
s/cm. Since there was an induction period, the solid polymer electrolyte could be prepared very easily. (Example 5) Solution A and solution B of Example 1 were mixed at 1:1.
Mix according to weight ratio and immediately add polypropylene non-woven fabric (
(manufactured by Nippon Vilene, 40 microns thick). Since there was a sufficient induction period until curing, a translucent solid polymer electrolyte film could be obtained very easily. The ionic conductivity of this film was measured using the AC impedance method and was found to be 1.6 x 10-3 at room temperature.
s/cm.

[0059]

Effects of the Invention The method for producing the solid polymer electrolyte of the present invention requires only the operation of mixing two liquids at room temperature, and is therefore extremely simple and extremely advantageous as a production process. In addition, the obtained solid polymer electrolyte has a high ionic conductivity of 10-6 S/cm or more at 0°C and has good adhesion with electrodes, making it suitable for use in lithium batteries, plastic batteries, and large-capacity capacitors. It can be applied to a wide range of applications as a solid-state ionics device, such as for all-solid-state devices such as electrochromic displays.

Claims (1)

[Claims] 1. At least one of liquid A or liquid B contains a radical polymerization retarder, an alkali metal salt and/or an ammonium salt, and is obtained by mixing both liquids A and B. A method for producing a solid polymer electrolyte. However, liquid A is a solution in which a radical polymerization initiation accelerator is dissolved in the compound represented by the general formula (1), and is [Formula 1] (wherein, R1 is hydrogen, or an alkyl group having 1 to 5 carbon atoms, is an alkyl group having 1 to 5 carbon atoms, and m is an integer of 2≦m≦30.) Liquid B is a compound represented by the general formula (2) [Formula 2] (wherein, R3, R5 is an alkyl group 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 represented by general formula (3). represents a compound [Chemical formula 3], R6 is a hydrocarbon group having 1 to 6 carbon atoms, R7
and R8 is a simple bond or carbon number 1-3
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 connected to each other to form a ring, and p, q and
r is 0 or 1, and p+q+r>0, except when R4 is a cyano group. ) is a solution in which a radical polymerization initiator is dissolved.