JPH0826162B2 - Polyelectrolyte - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polymer electrolyte, and more particularly to a polymer electrolyte which can be used in a wide temperature range and is chemically stable.

[Conventional technology]

In order to apply polymer electrolytes to prevent plastic static electricity and to apply to batteries and electrochemical devices, it exhibits good ionic conductivity over a wide temperature range from low to high temperatures, and has good storage stability. In addition, it is necessary that the material be easily manufactured. However, no polymer electrolyte has been developed so far that totally satisfies such required performances.

For example, conventionally, organic solvents such as 1,2-dimethoxyethane and propylene carbonate have been widely used, but these are generally used at a high temperature range of 60 to 80 ° C due to the relationship between boiling point and vapor pressure. Destruction, etc.). Recently, as a method for improving the disadvantages of these organic solvents, researches on polymer electrolytes have been actively conducted centering on polyethylene oxide (hereinafter abbreviated as PEO).

PEO various periodic table I a or Group II a group belonging to the metal salt, for _{example, LiCF 3 SO 3, LiI,} LiClO 4, NaI, NaCF 3 SO 3,
It forms a complex with KCF ₃ SO ₃ etc. and shows relatively good ionic conductivity in a certain temperature range (eg, P. Vashista et al. Fast Ion Transport in Soli
d), p.131 (1979)), and also has good storage stability. However, the ionic conductivity of PEO has a large temperature dependence, and shows good ionic conductivity at 60 ° C or higher, but the ionic conductivity deteriorates significantly at 20 ° C or lower, and it can be used in a wide temperature range. It was difficult to incorporate it into a product with a certain nature. As a method of improving ionic conductivity using low molecular weight PEO,
The method of introducing a low molecular weight PEO into the side chain of a vinyl-based polymer is called Day Banister (DJBanister).
, Polymer, 25, 1600 (1984
Year). However, although this polymer material formed a complex with a Li salt, its ionic conductivity at 20 ° C or lower was insufficient. Furthermore, a material in which low molecular weight PEO is introduced into the side chain of polysiloxane is the material of the Journal of Power Source by Watanabe et al.
e) Volume 20, page 327 (1987) and JP-A-63-136409, but these materials also have insufficient ionic conductivity at 20 ° C or lower. In addition, low molecular weight PEO
Polymer materials that alternately combine silicon and silicon compounds can be found in Nagaoka et al.'S Journal of Polymer Science; Polymer Letter Edition.
ence, Polymer Letter Edition), Vol. 22, p. 752 (1982)
Also, JP-A-60-216462 has been reported, and a silicone-based material is also disclosed in Polymer Polymerization (PGHall) et al.
nication) 27, 98 (1986). These polymer materials give high ionic conductivity over a wide temperature range from low temperature below 20 ℃ to high temperature above 60 ℃. However, these polymer materials cannot be protected from deterioration due to decomposition of the polymer material when used for a long period of time in electronic devices, and are notable for practical application. It was a disadvantageous material.

[Problems to be Solved by the Invention]

A first object of the present invention is to provide a novel chemically stable polymer electrolyte which has a high ionic conductivity even in a low temperature range below room temperature and does not deteriorate even when it is held or used for a long period of time. is there.

[Means for solving the problem]

As a result of intensive studies to solve the above problems, the present inventors have found that the above-mentioned object is at least a copolymer of a polysiloxane represented by the general formula (I) and a polyalkylene glycol. A polymer compound containing at least one side chain of the polysiloxane containing a polyalkylene glycol group and a salt of a metal ion belonging to Group Ia or IIa of the periodic table. Achieved by a characteristic polyelectrolyte.

(In the formula, R represents a hydrogen atom, an alkyl group, or an aryl group, and j represents an integer of 1 to 16.) In the polymer compound of the present invention, the polysiloxane and the polyalkylene glycol group in the main chain It is preferable that at least one side chain containing is linked by a silicon-carbon bond from the viewpoint of stability with time at high temperature.

R in the general formula (I) is preferably a hydrogen atom, a methyl group or an ethyl group. j is preferably an integer of 2 to 20.

Since the polymer material of the present invention has an alkylene glycol group in both the main chain and the side chain, it has a high dielectric constant and is excellent in the ability to dissolve and dissociate the supporting electrolyte. Further, since the main chain has siloxane, it has a low glass transition temperature (Tg), which is considered to facilitate the movement of ions. Also, since it is a high molecular compound, it has no boiling point,
It is also considered to have high stability at high temperatures.

Furthermore, since a bulky substituent having a polyalkylene glycol group is introduced into at least one side chain, it is remarkably time-lapsed as compared with a conventionally known polymer material composed of a copolymer of dimethylsiloxane and polyalkylene glycol. It is surprising that the stability at high temperature is significantly improved, and it is possible to prevent deterioration at high temperatures, which is not possible with conventional polymer electrolytes, to secure high ionic conductivity at low temperatures, and to secure chemical stability. With the present invention, a fundamental solution has been achieved.

The polymer compound of the present invention has at least the following general formula (II)
It is preferable to have a repeating unit represented by

(In the formula, L ₁ and L ₂ represent a divalent linking group, and L ₃ and L ₄ represent a (h + 1) -valent and a (h ′ + 1) -valent linking group. R ₁ , R ₂ , and R _{3 respectively.} , R ₄ , R ₅ and R represent hydrogen, an alkyl group or an aryl group, m and j represent an integer of 1 to 16 and m ′ represents an integer of 0 to 16. X ₁ , X ₂ and X ₃ And X ₄ is -O-, -S- or Represents R ₇ represents hydrogen, an alkyl group or an aryl group. a, b, c, a ', b', p, p ', l, l', n
And n ′ each independently represent 0 or 1, and h and h ′ each independently represent 1 or 2. ) The general formula (II) will be described in detail.

In the general formula (II), L ₁ and L ₂ represent a divalent linking group, which may be the same or different and have 1 to 1 carbon atoms.
The alkylene group, aralkylene group and oxaalkylene group of 10 are preferable. These groups may be substituted, and examples of the substituent include a halogen atom, a cyano group, a sulfo group,
Hydroxy group, carboxyl group, alkyl group, aryl group, aralkyl group, acyloxy group, acylamino group,
Amino group, sulfonamide group, alkoxy group, aryloxy group, alkylthio group, arylthio group, carbamoyl group, sulfamoyl group, alkoxycarbonyl group, aryloxycarbonyl group, alkylsulfonyl group, arylsulfonyl group, alkoxysulfonyl group, aryloxysulfonyl group , A carbamoylamino group, a sulfamoylamino group, a carbamoyloxy group, an alkoxycarbonylamino group, and an aryloxycarbonylamino group.

Typical examples of the preferred divalent linking group represented by L ₁ and L ₂ include methylene, ethylene, propylene and phenylene.

L ₃ and L ₄ are (h + 1) valence and (h '+ 1), respectively.
It represents a valent linking group and may be the same or different. When h = 1 or h ′ = 1, the linking group for L ₃ and L ₄ is preferably an alkylene group having 1 to 10 carbon atoms, an aralkylene group or oxaalkylene. When h = 2 or h ′ = 2, L ₃
Preferred linking groups for L ₄ and L ₄ are represented by the general formula (III).

(Where A is _{-CO -, - SO 2 -,} - CONH- or -CO-L ₇ -OL _{8 u}
Represents

B is Represents L ₅ , L ₆ , L ₇ and L ₈ may be the same or different and each represents a divalent linking group, preferably an alkylene group or an aralkylene group, and more preferably 1 to 1 carbon atoms.
6 is an alkylene group. p, q, r, s, t, and u each independently represent 0 or 1. ) Specific examples of L ₃ and L ₄ include -CH ₂ CH _2- , And so on.

These groups preferably have 1 to 12 carbon atoms, and these groups may be substituted. Examples of substituents
Examples of the substituent include the alkylene group of L ₁ .

X ₁ , X ₂ , X ₃ and X ₄ are —O—, —S— or Represents

R ₁ and R ₂ represent a hydrogen atom, an alkyl group or an aryl group, preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and particularly preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. . R ₃ , R ₄ , R ₅ , R ₆ and R are hydrogen atoms,
It represents an alkyl group or an aryl group, preferably a hydrogen atom, a methyl group or an ethyl group. a, b, c, a ',
b ', p, p', l, l ', n and n' each independently represent 0 or 1. Preferably, a, b, a'and b'are 0. 1 is preferable for p and p '. m and j are integers of 1 to 16, and 2 to 10 are particularly preferable. m'is an integer of 0 to 16, preferably 0 to 10. h and h '
Are each independently 1 or 2 and preferably h = h '.

The polymer compound of the present invention may have a plurality of repeating units of the general formula (II).

Examples of the remaining repeating units in the polymer compound of the present invention include dialkyl polysiloxane (eg, dimethyl polysiloxane) and polyalkylene oxide, which can improve film-forming properties.

The repeating unit represented by the general formula (II) is 50 in the polymer.
It is preferably contained in an amount of at least mol%. More preferably,
It is 80 mol% or more, and particularly preferably 100 mol%.

Typical examples of the polymer compound of the present invention are shown below. In addition, a representative example is represented by repeating units, but the polymer compound of the present invention is a polymer compound polymerized by these repeating units. Of course, the polymer compound of the present invention is not limited to these.

The weight average molecular weight Mw (in terms of polystyrene) of the polymer compound of the present invention is preferably 1000 to 80,000.

The metal ions belonging to Group Ia or Group IIa of the periodic table used in the present invention are preferably lithium, sodium, and potassium ions, and typical metal ion salts include LiCF ₃ SO ₃ , LiPF ₆ , and LiClO ₄ , LiI, LiBF ₄ , LiCF ₃ C
_{O 2, LiSCN, NaI, NaCF} 3 SO 3, NaClO 4, NaBF 4, NaAsF 6, K
_{CF 3 SO 3, KSCN, KPF} 6, KClO 4, etc. KAsF ₆ and the like.
More preferably, it is the above Li salt. These may be used alone or in admixture of two or more, or may be used in admixture with other electrolytes such as NBu ₄ BF ₄ .

The ratio of the polymer compound of the present invention to the metal ion salt is preferably such that the polyethylene oxide unit is contained in a ratio of 2 to 30 times that of the metal ion salt. More preferably, 6 to
20 times. If the ratio is too high, Tg rises and the ion conductivity decreases, and if the ratio is too low, the effective ion concentration decreases and the ion conductivity also decreases.

The polymer electrolyte of the present invention may be crosslinked by adding a crosslinking agent, or a polymer compound, other amphipathic compound or the like may be further added.

As a crosslinking group that may be added, as a crosslinking group, an epoxy group, an isocyanate group, an acid chloride group, an acid anhydride group,
Those having an active ester group can be used. Examples of the compound of the crosslinking agent are shown below, but the invention is not limited thereto.

(1) Examples of crosslinking agent compounds As the polymer compound that may be added, the following representative examples are used, but the polymer compounds are not limited thereto, and those compatible with the polymer compound of the present invention can be preferably used.

Compound Example (C-6) CH ₂ —CH ₂ —O _n As the amphipathic compound that can be added, any known amphipathic compound can be added. The representative examples are shown below, but are not limited to these.

Compound Example (C-9) C ₁₆ H ₃₃ OCH ₂ CH ₂ O ₁₅ CH ₃ Compound Example (C-10) C ₁₂ H ₂₅ OCH ₂ CH ₂ O ₃₀ C ₁₂ H ₂₅ Representative examples of the solvent that dissolves the polymer compound of the present invention and a salt of a metal ion include nitriles such as acetonitrile and benzonitrile; carbonates such as propylene carbonate and ethylene carbonate; tetrahydrofuran, 3
-Methyl-tetrahydrofuran, 2-methyl-tetrahydrofuran, tetrahydropyran, 1,3-dioxane, 1,4-dioxolane, 1,2-dimethoxyethane and other ethers: γ-butyrolactone, δ-butyrolactone and other lactones: Examples include dimethyl sulfoxide, tetramethylene sulfone, and dimethylformamide.
It is not necessarily limited to these. These solvents may be used alone or in combination of two or more.

The polymer electrolyte of the present invention can also be used as an antistatic material for plastic materials, batteries, and materials for various electrochemical devices such as electrochromic display devices and capacitors.

Typical synthetic examples of the polymer compound containing the repeating unit represented by the general formula (I) of the present invention are shown below.

Synthesis Example 1 Compound a repeating unit containing 100% represented by P-1 Synthesis of (P-1 _{polymer) (1) CH 2 = CH} -CH 2 -O-CH 2 CH 2 -O-CH 2 CH 2 - O-
Synthesis of CH ₃ (D-1) Diethylene glycol monomethyl ether 12g (0.1mo
l) was dissolved in 50 ml of t-amino alcohol, and 12 g (0.107 mol) of potassium t-butoxide was added thereto. With stirring at room temperature, 15 g (0.12 mol) of allyl bromide was added dropwise over 30 minutes. Then, the mixture was reacted at 70-80 ° C for 2 hours. After the reaction, the precipitated inorganic salt was passed, the solvent was distilled off from the liquid, and the residue was distilled under reduced pressure (75 to 83 ° C./2 mmHg) to obtain the desired product.

Yield 11.5 g (72% yield) The chemical structure was confirmed by NMR, IR, elemental analysis and GC.

Compound D-1 10 g (0.062 mol), dichlorodihydrosilane 3.5 g (0.035
mol) into a 100 ml autoclave and add chloroplatinic acid to it.
100 mg (0.1 mmol) was added and reacted at 50 ° C. for 2 hours. After the reaction, the contents were taken out, and unreacted dichlorodihydrosilane was distilled off to obtain the intended product.

Yield 12.6 g (96% yield) The chemical structure was confirmed by NMR, IR, elemental analysis and GC.

(3) Synthesis of a compound (P-1 polymer) containing 100% of the repeating unit represented by P-1 Tetraethylene glycol 7.6 g (0.038 mol) and pyridine 6.3 g (0.08 mol) are dissolved in toluene 50 ml and nitrogen is added. In a gas flow, a toluene solution of 10 g (0.038 mol) of compound D-2 was added dropwise at room temperature, and then reacted at 50-60 ° C for 4 hours. After the reaction, the precipitated hydrochloride of pyridine was removed, and the solvent was distilled off under vacuum to obtain the desired product. (Colorless and slightly viscous oil) Yield 14.1 g (Yield 97%) Nw = 4,800 The chemical structure was confirmed by NMR, IR and elemental analysis.

Compounds containing a repeating unit represented by the Synthesis Example 2 P-4 100% synthetic (P-4 _{polymer) (1) CH 2 = CH} -CH 2 -OCH 2 CH 2 O 2 CH 2 CH 2 -O-CH
Synthesis of ₃ (D-3) 16 g of triethylene glycol monomethyl ether (0.1
mol) was dissolved in 50 ml of t-amyl alcohol, and 12 g (0.11 mol) of potassium t-butoxide was added thereto. With stirring at room temperature, 15 g (0.12 mol) of allyl bromide was added dropwise over 30 minutes,
Then, the mixture was reacted at 70-80 ° C for 2 hours. After the reaction, the precipitated inorganic salt was removed by filtration, the solvent was distilled off from the solution, and the residue was distilled under reduced pressure (90 to 92 ° C / 1 mmHg) to obtain the desired product.

Yield 11.5 g (56% yield) The chemical structure was confirmed by NMR, IR, elemental analysis and GC.

Compound D-3 11g (0.054mol), dichloromethylhydrosilane 9.2g
(0.081mol) in a sealed tube, chloroplatinic acid 100mg
(0.1 mmol) was added, and the mixture was reacted at 50 ° C for 2 hours. After the reaction, remove the contents and distill under reduced pressure (150-161 ℃ / 1mm
Hg) The desired product was obtained.

Yield 12.8g (Yield 74%) The chemical structure was confirmed by NMR, IR, elemental analysis and GC.

(3) Synthesis of compound (P-4 polymer) containing 100% of repeating unit represented by P-4 Tetraethylene glycol 7.6 g (0.038 mol) and pyridine 6.3 g (0.08 mol) are dissolved in toluene 50 ml, A toluene solution of compound D-4 12.1 g (0.038 mol) was added dropwise at room temperature in a nitrogen gas flow. Then, it reacted at 50-60 degreeC for 4 hours. After the reaction, the precipitated hydrochloride of pyridine was removed, and the solvent was distilled off under vacuum to obtain the desired product. (Colorless and slightly viscous oil) Yield 14.9 g (yield 89%) Nw = 5,800 The chemical structure was confirmed by NMR, IR and elemental analysis.

〔Example〕

 Hereinafter, a detailed description will be given using examples.

Example 1 P-1 polymer and LiCF ₃ SO ₃ were dissolved in acetone at room temperature so that the composition ratio shown in Table 1 was obtained. At this time, P-1
The polymer concentration was 30 wt%. Then, the solvent was treated under vacuum (10 ^-2 to 10 ^-3 torr) at room temperature for 24 hours and at 60 ° C for 24 hours to completely remove the solvent to obtain a transparent homogeneous viscous solution.
() P-4 polymer, LiCF instead of P-1 polymer
_An identical solution was obtained except that LiClO ₄ was used instead of ₃ SO ₃ . () Instead of the P-1 polymer for comparison, JP-A-60-
A solution identical to that described in No. 216462 except that the following compound (E-1) was substituted was obtained. (Iroha) 20 volumes of Journal of Power Sources instead of P-1 polymer
The following compounds (E-
A solution identical to that obtained in place of 2) was obtained.
(Nihohe) Further, instead of P-1 polymer, JP-A-63-1364
A solution identical to that of No. 09 except that the following compound (E-3) was substituted was obtained. (Tochiri) The viscous liquid thus obtained is placed in a glass cell of 1 cm, the Pt electrode is set at a distance of 0.5 cm and immersed, and the impedance is measured at 0.1 Hz to 100,000 Hz (measurement temperature 2
Then, the ionic conductivity was determined from the Cole-Cole plot.

The stability of the polymer was evaluated by the following method. 25 ℃
Each compound was dissolved in an acetonitrile-water buffer solution having a pH of 4.2 (concentration 5 wt%), and the decomposition into monomers was traced by gel permeation chromatography (GPC).

 The results of these measurements are shown in Table 1 and FIG.

As can be seen from Table 1, Iroha of Examples of the present invention and Comparative Examples have good ionic conductivity near room temperature.
It can be seen from FIG. 1 that Comparative Example (E-1) is remarkably poor in decomposition into monomers. (E-2) and (E-3) have low decomposability into monomers and are good, but have poor ionic conductivity. It will be apparent that these are simultaneously improved in the present invention.

〔The invention's effect〕

According to the present invention, a polymer electrolyte having excellent ion conductivity at room temperature or lower and good stability can be obtained.

[Brief description of drawings]

FIG. 1 shows decomposition of P-1 polymer, P-4 polymer, E-1, E-2 and E-3 compounds in Example 1 into monomers.

Claims (3)

[Claims] At least one side chain of the polysiloxane contains a repeating unit whose main chain is a copolymer of a polysiloxane represented by the general formula (I) and a polyalkylene glycol. 1. A polymer electrolyte comprising a polymer compound containing an alkylene glycol group and a salt of a metal ion belonging to Group Ia or IIa of the periodic table. (In the formula, R represents a hydrogen atom, an alkyl group, or an aryl group, and j represents an integer of 1 to 16.) 2. At least one containing a polysiloxane and a polyalkylene glycol group in the main chain of the polymer compound.
The polymer electrolyte according to claim (1), which is a polymer compound whose side chains are linked by silicon-carbon bonds. 3. The polymer electrolyte according to claim 1, wherein the polymer compound is a polymer compound containing at least a repeating unit represented by the following general formula (II). (In the formula, L ₁ and L ₂ represent a divalent linking group, and L ₃ and L ₄ represent a (h + 1) -valent and a (h ′ + 1) -valent linking group. R ₁ , R ₂ , and R _{3 respectively.} , R ₄ , R ₅ and R represent hydrogen, an alkyl group or an aryl group, m and j represent an integer of 1 to 16, and m ′ represents an integer of 0 to 16. X ₁ , X ₂ , X ₃ ,
X ₄ is -O-, -S- or R ₆ represents hydrogen, an alkyl group or an aryl group. a, b, c, a ', b', p, p ', l, l', n
And n ′ each independently represent 0 or 1, and h and h ′ each represent 1 or 2.