JP3105137B2 - Composite solid electrolyte - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite solid electrolyte useful as a primary battery, a secondary battery, an electrochromic display device and the like.

[0002]

2. Description of the Related Art Recently, organic conductors having electron conductivity comparable to that of metals have been found, and some of them have already begun to be considered for their practical use. However, although the development of ionic conductors is progressing mainly with inorganic crystals, glass, ceramics, etc., organic materials have not yet been put to practical use. Compared to inorganic ion conductors, polymer-based materials have 1) lower specific gravity, 2) easy molding, 3) flexible and thin films can be easily obtained, and 4) relatively high ion conductivity at room temperature. It has features such as having properties. On the other hand, the characteristics required as general solid electrolytes including polymer electrolytes are 1) high mechanical strength that can withstand thinning, 2) high ionic conductivity, 3) moldability, 4) control of stability, etc. In particular, 1) and 2) are emphasized. At present, the organic materials that are mainly studied are roughly classified into two types, namely, a so-called gel electrolyte system in which a polyethylene oxide system, a crosslinked polymer and an organic electrolyte are combined.

[0003]

However, in order to make the amorphous form of a polyethylene oxide based on a crystalline polymer, an oligomer having a molecular weight of about several hundred (polymerization degree of 10 or less) must be used. In this case, a film cannot be formed because the liquid is completely fluid. To eliminate this drawback, polyethylene oxide can be partially cross-linked,
Attempts have been made to copolymerize or blend with other polymers, but there are problems such as poor ionic conductivity, insufficient strength, and macro phase separation. On the other hand, on the other hand, in order to contain an organic electrolyte in a polymer, for example, a method of dissolving the organic electrolyte in the polymer to form a semi-solid form (Japanese Patent Laid-Open No. 54-10454), a non-aqueous electrolyte (PCT / JP91 / 00362, international publication number WO
91/14294) have been proposed. However, the former method involves the problem that the electrolyte oozes out of the polymer and the solid strength is extremely weak, and the latter method has a solid strength (elastic modulus) of 10 ² to 10 ⁵ dyne. Although it is slightly improved to / cm ² , it is used for separators used in lithium batteries, etc. (porous film required to prevent contact between cathode and anode in non-aqueous electrolyte batteries and to hold electrolyte) Required 10 ⁷ -10 ⁸ dyn
Since the strength was far from e / cm ² , the crosslinked polymer itself could not serve as a separator. When the degree of cross-linking of the polymer is increased, the ionic conductivity is extremely lowered.

[0004] On the other hand, the applicant has previously filed Japanese Patent No. 182047 (a).
Has proposed a block-graft copolymer substantially the same as that used in the present invention and a method for producing the same. In Japanese Patent No. 182048 (b), in order to increase the ionic conductivity of this block-graft copolymer, 0.05 to 80 mol% of Li, N based on the alkylene oxide unit is used.
a block in which an inorganic salt containing at least one element selected from a, K, Cs, Ag, Cu and Mg is mixed;
A graft copolymer composition was proposed. Japanese Patent Publication No. 5-74195 (c) discloses a lithium battery containing a similar composite of a block-graft copolymer and a lithium ion salt as an electrolyte, and Japanese Patent Application Laid-Open No. 3-188151 (d) discloses a lithium battery.
A block-graft copolymer composition obtained by adding a polyalkylene oxide to the same inorganic ion salt composite of a block-graft copolymer was proposed. The above b,
In the inventions (c) and (d), the obtained block-graft copolymer is dissolved by adding an organic solvent for dissolving the same together with an inorganic salt and the like, and after molding, the organic solvent is dried and removed, and used as a solid electrolyte. Was. However, none of the solid electrolytes satisfies both the high mechanical strength and the high ionic conductivity that can withstand thinning, which are the essential characteristics of the solid electrolyte. Accordingly, an object of the present invention is to provide a composite solid electrolyte having high mechanical strength, high ionic conductivity, moldability, stability, and the like, as well as a polymer solid electrolyte.

[0005]

The composite solid electrolyte according to the present invention comprises a block chain A of at least one polymer having a degree of polymerization of 10 or more and comprising a repeating unit represented by the following general formula: The block chain A and the block chain B are composed of at least one type of polymer having a degree of polymerization of 300 or more and composed of a repeating unit represented by the formula: The block-graft copolymer having a degree of polymerization of 310 or more, which is 1, contains an inorganic salt and a cyclic carbonate-based organic solvent.

Embedded image (Where R ¹ is a hydrogen atom, a methyl group or an ethyl group,
R ² is a hydrogen atom or a methyl group; R ³ is an alkyl group, an aryl group, an acyl group, a silyl group or a cyanoalkyl group, n is an integer of 1 to 100, and the number average of the graft chain represented by the following formula 5 Molecular weight is 45 ~ 4,400)

Embedded image

Embedded image (Where R ⁴ is a hydrogen atom, a methyl group or an ethyl group,
M has the formula _{-CH = CH 2, -C (CH} 3) = CH 2, -C
A group represented by OOCH ₃ or —COOC ₂ H ₅ , a phenyl group or a substituted phenyl group)

In the composite solid electrolyte, the cyclic carbonate based organic solvent is ethylene carbonate, propylene carbonate, γ-butyrolactone and 2-methyl-γ.
At least one cyclic ester selected from -butyrolactone, which contains at least an equivalent of the block-graft copolymer, wherein the inorganic salt is Li, Na, K,
At least one selected from Cs, Ag, Cu and Mg
Inorganic salts containing various kinds of elements are preferably contained in the block-graft copolymer in an amount of 0.05 to 80 mol% based on the alkylene oxide unit of the general formula:

The block-graft copolymer used here and the method for producing the same are almost the same as those disclosed in the aforementioned Japanese Patent No. 1842047. In the block-graft copolymer, at least one block chain A or B of the same or different type of repeating units represented by the general formulas 4 and 6 is used, for example, A ¹ B ¹
, B ¹ A ¹ , B ¹ A ¹ B ¹ , B ¹ A ¹ B ² , B ¹ A ¹ B
² A ¹ B ¹ arbitrarily arranged. The degree of polymerization of the block chain A of the polymer is 10 or more, and
Has a polymerization degree of 300 or more, and the block-graft copolymer obtained therefrom has a polymerization degree of 310 or more. Since the block chain A of the polymer functions as a polyelectrolyte, if the degree of polymerization is less than 10, it does not show the microphase separation structure characteristic of this polymer, and the block chain B retains mechanical strength. The degree of polymerization is 3
If it is less than 00, the mechanical strength of the polymer decreases. It is necessary that the component ratio of both block chains A and B is 1:30 to 30: 1. If the ratio is 1:30 or less, the graft component is too small to maintain the function as a solid polymer electrolyte,
When the ratio is 30: 1 or more, it is difficult to maintain the mechanical strength of the block chain as a stem molecule.

To obtain this block-graft copolymer, for example, a compound represented by the following general formula: ## STR7 ## wherein R ¹ is as defined above
And a block chain C of at least one kind of polymer composed of at least one polymer composed of a repeating unit represented by the following general formula: A block copolymer T serving as a backbone molecular chain is synthesized, and then a hydroxyl group of a side chain of the block copolymer has a general formula RMe (where R is t-butyl ether, diphenylethylene, benzyl, naphthalene or A cumyl group, Me is a sodium, potassium or cesium atom) to form a carbanion by reaction with an organic alkali metal represented by the following general formula: wherein R ² is the same as defined above. By adding an alkylene oxide to grow the graft chain.

Embedded image

Embedded image

At this time, a block copolymer T as a trunk molecular chain composed of block chains C and B used as a starting material is first exemplified by 4-hydroxystyrene, 4- (1-methylethenyl) phenol and the like. The monomer compound containing the residue represented by the general formula:
The phenolic hydroxyl group is protected with a trialkyl group or a trialkylsilyl group, and a vinyl compound such as styrene or α-methylstyrene; a diene compound such as butadiene and isoprene; methyl acrylate, ethyl acrylate, methyl methacrylate, A block polymer having a repeating unit represented by the above general formula: embedded image and synthesized from a monomer compound exemplified by an acrylate ester such as ethyl methacrylate, a methacrylate ester; It can be obtained by polymerizing by a legal method and then hydrolyzing with an acid or the like.

Examples of the initiator used for the polymerization include organometallic compounds such as n-butyllithium, sec-butyllithium, tert-butyllithium, and 2-methylbutyllithium. In particular, n-butyllithium is preferable. This amount is selected according to the desired molecular weight, since it determines the molecular weight of the polymer obtained together with the amount of the charged compound. Since the degree of polymerization of the block chain C constituting the obtained block copolymer T is 10 or more, the concentration is usually ^adjusted to 10 ⁻² to 10 ⁻⁴ mol / liter in the reaction solution. The polymerization is generally carried out in an organic solvent, and examples of the organic solvent usable for this purpose include solvents for anionic polymerization such as benzene, toluene, n-hexane and tetrahydrofuran. The concentration of the monomer compound used for the polymerization in the reaction solution is appropriately 1 to 10% by weight, and the polymerization reaction is performed under a high vacuum at a pressure of 10 ⁻⁵ Torr or less, or purified to remove harmful substances such as moisture. It is preferable to carry out the stirring at room temperature in an atmosphere of an inert gas such as argon or nitrogen. The elimination reaction of the protecting group can be easily carried out by adding an acid such as hydrochloric acid or hydroiodic acid dropwise with heating in a solvent such as dioxane, acetone, methyl ethyl ketone or acetonitrile.

The carbanionation of the hydroxyl group of the block copolymer T thus obtained is carried out at a concentration of 1
To 30% by weight, preferably 1 to 10% by weight, in a solvent for anionic polymerization such as tetrahydrofuran, to which an organic alkali metal is dissolved in a suitable solvent such as tetrahydrofuran and added. It is performed by stirring for a time. As the organic alkali metal used in this reaction, for example, potassium t-butoxy, potassium naphthalene, potassium diphenylethylene, potassium benzyl,
Examples thereof include cumyl potassium, sodium naphthalene, and cumyl cesium, and among them, potassium t-butoxide is particularly preferable. Confirmation of this reaction was performed by reacting the product with trimethylsilyl chloride, precipitating in methanol, purifying, drying and isolating a sample obtained.
It can be carried out by measuring the disappearance of hydroxyl groups and the amount of increase of trimethylsilyl groups by ¹ H-NMR, and the reaction of organic alkali metals to hydroxyl groups can be quantitatively grasped. Further, it can be confirmed from the GPC elution curve that the block chain has not undergone crosslinking or decomposition reaction.

Carbanionized block copolymer T
Is added with an alkylene oxide represented by the above general formula: for example, ethylene oxide, propylene oxide or the like in the form of a vapor or a liquid.
Stirring at ~ 80 [deg.] C for 1-48 hours can result in a block-graft copolymer. The polymerization solution containing the alkylene oxide precipitates when poured into water, and can be isolated by filtering and drying. Characterization is performed by measuring the number average molecular weight with a membrane osmometer and measuring the infrared absorption spectrum, ¹
The structure and composition are determined by H-NMR, and the length and number of the graft chains can be determined from the results. Further, it is possible to determine whether or not the target substance has been isolated and to estimate the molecular weight distribution based on the GPC elution curve. The polymerization of the block copolymer T serving as the trunk molecular chain and the reaction for growing the branch molecular chain thereof are usually carried out in an organic solvent. Examples of the organic solvent usable for the polymerization include tetrahydrofuran, dioxane, tetrahydrofuran, and the like. Solvents for anionic or ring-opening polymerization, such as pyran and benzene, are preferred. Examples of the compound used for terminating the polymerization include acids such as acetic acid; halides such as methyl bromide and benzyl chloride; silyl compounds such as trimethylsilyl chloride and t-butyldimethylsilyl chloride;

The control of the length of the graft chain is determined by the number of moles of the block chain C contained in the block-graft copolymer, the amount of the organic alkali metal at the time of carbanionation, and the amount of the alkylene oxide. . That is, the amount of the organic alkali metal must not exceed the number of moles of the block chain C, and the length of the graft chain is represented by the following equation (1).

(Equation 1) For example, to produce a block-graft copolymer having a graft chain length of 2,000 in number average molecular weight, a block-graft copolymer containing 7 × 10 ^-3 moles of the block chain C can be obtained by:
After adding 5 × 10 ⁻³ mol of an organic alkali metal to form a carbanion, 22 g of an alkylene oxide may be added. Further, in order to produce a block-graft copolymer having a number average molecular weight of 45, all of the above components may be equimolar. Further, when the number average molecular weight is from 45 to 4,400, it can be achieved by arbitrarily selecting an intermediate mole number.

The composite solid electrolyte of the present invention can be obtained by adding an inorganic salt and a cyclic carbonate-based organic solvent to the block-graft copolymer thus obtained. This inorganic salt is Li, Na, K, C
containing at least one element of s, Ag, Cu and Mg, specifically, LiClO ₄ , LiI, Li
SCN, LiBF ₄ , LiAsF ₆ , LiCF ₃ SO
₃ , LiPF ₆ , NaI, NaSCN, NaBr, Na
PF ₆ , KI, KSCN, KPF ₆ , KAsF ₆ , Cs
SCN, CsPF ₆ , AgNO ₃ , CuC ₁₂ Mg (Cl
O ₄ ) ₂ , RbCu ₄ I _1.75 Cl _{3.25 and the} like, which are used alone or in combination of two or more.

The cyclic carbonate-based organic solvent has very high compatibility with the graft chain of the block-graft copolymer, but does not dissolve the block chain B (portion retaining mechanical strength) at all. It forms a non-aqueous electrolyte having a high dielectric constant and a boiling point, and excellent in solubility in inorganic salts, ion dissociation, etc., and in the composite solid electrolyte of the present invention, a strong osmotic pressure acting on the graft chain. Thus, the liquid state is stably maintained. Examples of such a cyclic carbonate-based organic solvent include at least one cyclic carbonate selected from ethylene carbonate, propylene carbonate, γ-butyrolactone, and 2-methyl-γ-butyrolactone. Further, for the purpose of reducing the viscosity, 1,2-dimethoxyethane, methoxyethoxyethane, dioxolan,
At least one solvent having a low boiling point selected from 4-methyldioxolan, 2-methyldioxolan, diethyl carbonate, acetonitrile, tetrahydrofuran, and 2-methyltetrahydrofuran may be added. The mixing ratio of the low boiling point solvent to the cyclic carbonate in the latter mixture is preferably 0.1 to 50% by weight, particularly preferably 0.5 to 10% by weight. The concentration of the inorganic salt relative to the cyclic carbonate-based organic solvent is preferably from 0.1 to 5 mol / l, particularly preferably from 0.5 to 3 mol / l. The content of the non-aqueous electrolyte obtained by dissolving the inorganic salt in the cyclic carbonate-based organic solvent with respect to the block-graft copolymer is 100% by weight or more, particularly 300 to 7%.
00% by weight is preferred.

The method of blending the inorganic salt and the cyclic carbonate-based organic solvent into the block-graft copolymer is not particularly limited. For example, an inorganic salt and a cyclic carbonate-based organic solvent are added to the block-graft copolymer. A method of adding and mechanically kneading at room temperature or under heating, dissolving a block-graft copolymer and an inorganic salt in a common good solvent, forming a film, and forming the obtained film into a cyclic carbonate-based organic solvent. It can be arbitrarily selected, for example, a method of immersion in water. In particular, the latter method is convenient for preparing a membrane-shaped composite fixed electrolyte because the saturated amount of the cyclic carbonate-based organic solvent that can hold the block-graft copolymer is primarily determined by the composition ratio of the graft chain. It can be said that the method is highly reproducible.

[0017]

EXAMPLES Hereinafter, specific embodiments of the present invention will be described in more detail with reference to Examples and Comparative Examples. In addition, the block copolymer in an example connects each component by "-b-", for example, polystyrene, poly-p-hydroxystyrene, and a three-component ternary block copolymer of polystyrene ",
"Poly (styrene-bp-hydroxystyrene-b-
Styrene) ".

Example 1-1 [Poly (styrene-bp-
Hydroxystyrene-b-styrene) ... Synthesis of Block Copolymer T to be Trunk Molecular Chain] Under high vacuum of 10 ^-5 Torr, 1.1 × 10 ^-4 mol of n-butyllithium as an initiator is added to 540 ml of tetrahydrofuran as an initiator. I charged. The mixed solution was kept at -78 ° C, 5.6 g of styrene diluted with 80 ml of tetrahydrofuran was added, and polymerization was carried out with stirring for 30 minutes. The reaction solution turned red. Next, p-tert diluted with 90 ml of tetrahydrofuran
4.1 g of butoxystyrene was added and polymerized under stirring for 15 minutes. This solution also turned red. 5.6 g of styrene diluted with 80 ml of tetrahydrofuran was added thereto, and further
The polymerization was carried out under stirring for 10 minutes. This solution also turned red. After completion of the polymerization, the reaction mixture was poured into methanol, and the obtained polymer was precipitated, separated, and dried.
15.3 g of a white polymer was obtained. ^From the results of ¹ H-NMR,
This is styrene 73%, p-tert-butoxystyrene 27%
It was found to be a block copolymer consisting of G
The PC solution curve showed a sharp single peak, confirming that the polymer was a single polymer. The number average molecular weight of this polymer was 14 × 10 ⁴ , and the degree of polymerization of each monomer was 488 for styrene at both ends and 211 for p-tert-butoxystyrene, respectively.
The total was 1,187. Next, the block copolymer was dissolved in a mixed solvent of acetone and benzene, and the solution was heated to 30 ° C. using hydrochloric acid.
It was hydrolyzed in 3 hours to synthesize poly (styrene-bp-hydroxystyrene-b-styrene) containing 40 parts of styrene / 20 parts of p-hydroxystyrene / 40 parts of styrene. The ratio and molecular weight of styrene / p-hydroxystyrene / styrene in the poly (styrene-bp-hydroxystyrene-b-styrene) can be arbitrarily selected from the charged amount and the concentration of the initiator.

Example 1-2 [Poly (styrene-bp-
(Hydroxystyrene-b-styrene) Carbanionation of Block Copolymer T to be Trunk Molecular Chain with Organic Alkali Metal] 10 g of the poly (styrene-bp-hydroxystyrene-b-styrene) obtained in the preceding example was obtained. Dissolved in 200 ml of tetrahydrofuran under high vacuum. 0.07 at 25 ° C
Molar potassium t-butoxide was added. After stirring this solution for 1 hour, 0.5 mol of trimethylsilyl chloride was further added to cause a reaction, and the reaction solution was poured into methanol, and the obtained polymer was precipitated and separated. When this polymer was analyzed by ¹ H-NMR, it was confirmed that potassium reacted with the hydroxyl group, the peak of the hydroxyl group disappeared, and the peak of the trimethylsilyl group increased. From the elution curve of GPC, it was confirmed that the molecular weight distribution was the same as before the carbanionization, and neither a crosslinking reaction nor a decomposition reaction occurred. This example shows that the carbanionation of the hydroxy group of the block copolymer proceeds completely quantitatively, and that no side reaction such as decomposition or crosslinking of the main chain is involved.

Example 1-3 [Synthesis of block-graft copolymer from poly (styrene-bp-hydroxystyrene-b-styrene) with ethylene oxide;
Production of the composite solid electrolyte of the present invention in which LiClO ₄ and polypropylene carbonate were added thereto] 7.3 g of the poly (styrene-bp-hydroxystyrene-b-styrene) obtained in Example 1-1 was added to 10 ^-6 Torr
Was dissolved in 200 ml of tetrahydrofuran under high vacuum.
To this solution was added 9.49 mmol of potassium t-butoxide at 25 ° C, and after stirring for 1 hour, 11.9 g of ethylene oxide was added. This was kept at 65 ° C. and stirred for 24 hours. Thereafter, the polymerization was stopped by adding methyl iodide, and then the reaction mixture was poured into water to precipitate a polymer, separated and dried. The amount of the obtained polymer was 19.2 g.

[0021] Figure 1 this GPC elution curve, ¹ H-NM
The results of analysis by R are shown in FIG. Since the GPC elution curve was sharp and had a single peak, it was confirmed that this was a single polymer. The number average molecular weight of this polymer is
It was 33 × 10 ⁴ . From the ¹ H-NMR and the number average molecular weight, the length of the graft chain was 1,300 (degree of polymerization [30]).
The composition of polyethylene oxide was found to be 62%. The IR spectrum is shown in FIG. The absorption position of the graft chain in IR and ¹ H-NMR is IR
(Cm ⁻¹ ): C—O—C... 1115 cm ⁻¹ , ¹ H-NMR (δ,
ppm): OCH ₂ CH ₂ … 3.6 ppm. This block-
FIG. 4 shows the result of enlarging a film formed by dissolving the graft copolymer in 1,4-dioxane with an electron microscope. Osmic acid, which selectively stains only the polyethylene oxide that is the graft chain, is used as the dye, so the polyethylene oxide phase (graft chain) in which the black phase is dyed, and the polystyrene phase (stem in which the white phase is not dyed) Molecular chain). That is, it is understood that this film forms a clear microphase separation structure.

2 g of the block-graft copolymer thus obtained was dissolved in 50 ml of 1,4-dioxane. 5 ml of 0.4 g of LiClO ₄ dissolved in this solution
Was added and mixed uniformly, and then cast on a Teflon plate. The sample was allowed to stand at room temperature for 24 hours under an argon gas stream to remove excess solvent, and then further cooled to 60 ° C.
For 24 hours, and the obtained film was immersed in a propylene carbonate solution (non-aqueous electrolyte) in which 1 mol / liter of LiClO ₄ was dissolved for 1 hour. Next, the membrane was taken out from the non-aqueous electrolyte, the non-aqueous electrolyte adhering to both surfaces was wiped off with filter paper, and then dried at room temperature for 24 hours.
Although the obtained membrane (composite solid electrolyte) contains a non-aqueous electrolyte of 300% by weight based on the weight of the block-graft copolymer, it is a tough and dynamic viscoelasticity tester RSA-II ( RHEO
The elastic modulus by METRIC INC (trade name) is 10 ⁷ dyne / cm ²
The above is shown. Further, even when the composite solid electrolyte was compressed under a load of 10 kg / cm ² , the non-aqueous electrolyte contained therein did not flow out. This film was cut out into a disk shape with a diameter of 10 mm, electrodes were formed on both sides with lithium electrode plates sandwiched, and the frequency was 5 Hz to 5 MHz.
AC impedance measuring device: Multi-frequency
Ionic conductivity was calculated by the complex impedance method using LCRX meter model 4192A (trade name, manufactured by Yokogawa Hewlett-Packard Company). As a result, 1.8 × 10 ^-3 at 25 ° C.
A value of S / cm was obtained.

Example 2 2 g of the block-graft copolymer (number average molecular weight = 33 × 10 ⁴ , composition of polyethylene oxide: 62%) obtained in Example 1-3 was dissolved in 50 ml of 1,4-dioxane. After that, it was cast on a Teflon plate. The sample was allowed to stand at room temperature for 24 hours under a stream of argon gas to volatilize excess solvent, and then dried in vacuum at 90 ° C. for 24 hours to obtain a film from which the solvent was completely removed. Next, this film was immersed for 1 hour in a propylene carbonate solution (non-aqueous electrolyte) in which 1 mol / liter of LiClO ₄ was dissolved, so that the thickness was 1
A film-shaped composite solid electrolyte of 00 μm was formed. The obtained membrane was 420% by weight based on the weight of the block-graft copolymer.
Despite containing a non-aqueous electrolyte, the elastic modulus calculated from the measurement results with a tensile tester: Shimadzu Autograph DDS10T-S (manufactured by Shimadzu Corporation, trade name) is 3.9 × 10 ⁸ dyn
e / cm ² and elongation percentage were 70%. Even when the film was compressed under a load of 10 kg / cm ² , the non-aqueous electrolyte contained therein did not exude. This film is cut out into a disk shape with a diameter of 10 mm, conductive silver paste is applied to both sides to form electrodes,
AC impedance measuring device with a frequency of 5 Hz to 5 MHz: Ion conductivity was measured by the complex impedance method using a multi-frequency LCRX meter model 4192A (trade name, manufactured by Yokogawa Hewlett-Packard Company).
A value of 1.5 × 10 ⁻³ S / cm was obtained at ° C.

Examples 3 to 8 [Production of Composite Solid Electrolyte Using Different Types of Nonaqueous Electrolytes] Composites were prepared in the same manner as in Examples 1-3 except that the nonaqueous electrolyte was replaced with those shown in Table 1. When a solid electrolyte was manufactured and the same test was performed, the results as shown in Table 1 were obtained. From this, it was found that the composite solid electrolyte of the present invention hardly reduced the membrane strength while containing a large amount of non-aqueous electrolyte, and at the same time exhibited high ionic conductivity.

[0025]

[Table 1]

Examples 9 to 11 In Examples 1 to 3, block-graft copolymers having the graft chain composition shown in Table 2 were synthesized by changing the amount of ethylene oxide to be added. A composite solid electrolyte was produced in the same manner as above, except that it was changed to the one shown, and the same test was carried out. The results as shown in Table 3 were obtained.

[Table 2]

[0027]

[Table 3]

Comparative Example 1 Block-graft copolymer 2 obtained in Examples 1 to 3
g was dissolved in 50 ml of 1,4-dioxane. To this solution was added 5 ml of 1,4-dioxane in which 0.4 g of LiClO ₄ was dissolved, and the mixture was uniformly mixed and then cast on a Teflon plate. The sample was allowed to stand at room temperature for 24 hours under an argon gas stream to remove excess solvent, and then dried under reduced pressure at 60 ° C. for 24 hours to form a film. The resulting film has an elastic modulus of 7.2 × 10 ⁸ dy
The elongation was 90% at ne / cm ² , but the ionic conductivity was measured in the same manner as in Example 1. As a result, it was 0.9 × 10 ⁻⁵ S / cm.

Comparative Example 2 A film was formed in the same manner as in Comparative Example 1 except that 0.5 g of polyethylene glycol dimethyl ether having a molecular weight of 350 was added to the solution in which the block-graft copolymer was dissolved. The elastic modulus was measured to be 0.
24 × 10 ⁷ dyne / cm ² , elongation 15%, ionic conductivity 2.0
× 10 ^-3 S / cm.

Comparative Example 3 The films obtained in Examples 1 to 3 were replaced with 1 mol / L of Li
When immersed in a tetrahydrofuran solution in which ClO ₄ was dissolved, the film was instantaneously dissolved.
Measurement of ionic conductivity was not possible. Similar results were obtained when the solvent was changed to methoxyethoxyethane and diethyl carbonate.

[0031]

According to the composite solid electrolyte of the present invention, the constituent block-graft copolymer has 1) a clear microphase-separated structure, 2) a long stem molecule forms a pseudo-crosslinked structure, 3) Form a continuous phase even if the graft component is relatively low molecular. 4) Hold a large amount of non-aqueous electrolyte because the graft component has a function as a compatibilizer. It has various characteristics that it can be done. Therefore, the function can be shared between the stem molecular chain and the graft molecular chain of the block-graft copolymer. In particular, by selecting a polymer having a high glass transition point (T _g ) and high mechanical strength for the block chain and an amorphous polyalkylene oxide for the graft chain, it is possible to maintain the liquid retention of the electrolytic solution and to increase the metal ions. Mobility,
Alternatively, a functional polymer material having much higher performance than conventional polymers having polyalkylene oxide or gel electrolyte-based polymer can be obtained because it can have a complex forming property with an inorganic salt. Therefore, when the composite solid electrolyte of the present invention is applied to, for example, a battery, the obtained membrane eliminates the need for a separator, which was conventionally essential, so that it is very effective for miniaturization and thinning of the battery, and its high Due to the liquid retention property, volatilization and leaching of the non-aqueous electrolyte can be almost completely prevented, so that the safety is extremely high.

[Brief description of the drawings]

FIG. 1 is a graph showing a GPC elution curve of the block-graft copolymer obtained in Example 1-3.

FIG. 2 is a graph showing a ¹ H-NMR spectrum of the block-graft copolymer obtained in Example 1-3.

FIG. 3 is a graph showing an IR spectrum of the block-graft copolymer obtained in Example 1-3.

FIG. 4 is an explanatory diagram showing a film formed from the block-graft copolymer obtained in Example 1-3, enlarged by an electron microscope.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI // C08F 8/00 C08F 8/00 297/02 297/02 C08G 65/08 C08G 65/08 (C08K 13/02 3:00 5: 156) (72) Inventor Kenichi Ito 28, Nishifukushima, Nishifukushima, Nakakushiro-gun, Niigata Pref. Shin-Etsu Chemical Co., Ltd. 1 Shin-Etsu Chemical Co., Ltd. Corporate Research Center (56) References JP-A-2-229826 (JP, A) JP-A-5-120912 (JP, A) JP-A-4-36347 (JP, A) ( 58) Field surveyed (Int.Cl. ⁷ , DB name) H01M 6/18 C08K 13/02 C08L 53/00 C08L 71/00 H01B 1/06 C08F 8/00 C08F 297/02 C08G 65/08 C08K 13 / 02

Claims (5)

(57) [Claims] 1. A block chain A of at least one polymer having a degree of polymerization of at least 10 comprising a repeating unit represented by the following general formula: and a repeating unit represented by the following general formula: A block chain A and a block chain B composed of at least one block chain B of a polymer having a degree of polymerization of 300 or more.
A composite solid electrolyte comprising a block-graft copolymer having a degree of polymerization of 310 or more and a component ratio of 1:30 to 30: 1, containing an inorganic salt and a cyclic carbonate-based organic solvent. Embedded image (Where R ¹ is a hydrogen atom, a methyl group or an ethyl group,
R ² is a hydrogen atom or a methyl group, R ³ is an alkyl group, an aryl group, an acyl group, a silyl group or a cyanoalkyl group, n is an integer of 1 to 100, and a graft chain represented by the following formula 2 ] Has a number average molecular weight of 45 to 4,400). (Where R ⁴ is a hydrogen atom, a methyl group or an ethyl group,
M has the formula _{-CH = CH 2, -C (CH} 3) = CH 2, -C
A group represented by OOCH ₃ or —COOC ₂ H ₅ , a phenyl group or a substituted phenyl group) 2. The composite solid according to claim 1, wherein the cyclic carbonate-based organic solvent is at least one cyclic carbonate selected from ethylene carbonate, propylene carbonate, γ-butyrolactone and 2-methyl-γ-butyrolactone. Electrolytes. 3. The cyclic carbonate organic solvent according to claim 2,
The cyclic carbonate described above, and at least one low boiling point selected from 1,2-dimethoxyethane, methoxyethoxyethane, dioxolan, 4-methyldioxolan, 2-methyldioxolan, diethyl carbonate, acetonitrile, tetrahydrofuran and 2-methyltetrahydrofuran The composite solid electrolyte according to claim 2, which is a mixture with a solvent. 4. The organic solvent according to claim 1, wherein the cyclic carbonate organic solvent contains at least an equivalent of the block-graft copolymer.
The composite solid electrolyte according to claim 3. 5. The method according to claim 1, wherein the inorganic salt is Li, Na, K, Cs, Ag,
An inorganic salt containing at least one element selected from Cu and Mg, which is contained in the block-graft copolymer in an amount of 0.05 to 80 mol% based on the alkylene oxide unit of the general formula (1). The composite solid electrolyte according to claim 4.