JP2002270236A - Polymer gel electrolyte and cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high performance polymer gel electrolyte with high ion conductivity, containing electrolyte liquid with high density, which enables to manufacture a high performance nonaqueous electrolyte cell. SOLUTION: A liquid composed by dissolving vinylidene fluoride polymer (a), multifunctional monomer, and polymerization initiator of the multifunctional monomer in electrolyte liquid (I), is injected between a positive electrode and a negative electrode housed in a container housing above electrodes, and afterwards, the liquid is gelled by heating the container. The nonaqueous electrolyte cell is efficiently manufactured on the spot by forming the polymer gel electrolyte which is formed by solidifying the electrolyte liquid (I) by a matrix resin (II) having a good network structure of mutually penetrated vinylidene fluoride polymer (a) and a bridged polymer of the multifunctional monomer (b), thus, the nonaqueous electrolyte cell is efficiently manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polymer gel electrolyte suitable for forming a non-aqueous battery, particularly a lithium ion battery, a non-aqueous battery using the polymer gel electrolyte, a method for producing the non-aqueous battery, and The present invention relates to a precursor composition for forming the polymer gel electrolyte.

[0002]

2. Description of the Related Art In recent years, the development of electronic technology has been remarkable, and various devices have been reduced in size and weight. Along with the miniaturization and weight reduction of this electronic device, the demand for the miniaturization and weight reduction of a battery serving as a power source for the electronic device has also become very large. Non-aqueous secondary batteries using lithium are used as power sources for small electronic devices mainly used in homes such as mobile phones, personal computers, and video camcorders as batteries capable of obtaining greater energy with a small volume and weight. Have been. In order to further improve the performance of this lithium nonaqueous secondary battery, it has been proposed to use a polymer electrolyte as an ion transfer medium between a positive electrode and a negative electrode.

That is, since the polymer electrolyte is used as the ion transfer medium, there is no liquid leakage as compared with the conventional one using the electrolyte as the ion transfer medium, so that the reliability and safety are improved, and the thickness is further reduced. The advantage that the degree of freedom in shape is increased is obtained, and further simplification and weight reduction of the package are expected.

A polymer electrolyte containing no electrolyte is difficult to satisfy the characteristics required for battery application, such as low ionic conductivity and a low discharge capacity of the battery. Therefore, the polymer electrolyte contains an electrolyte (electrolyte solution). Attention has been focused on polymer gel electrolytes having high ionic conductivity. It is known that the ionic conductivity generally increases as the amount of the electrolyte in the polymer gel electrolyte increases. On the other hand, this polymer gel electrolyte has a strong membrane strength from the viewpoint of battery miniaturization, high energy density, etc., and from the viewpoint of battery operating temperature range, safety, etc. Therefore, it is desired to maintain the insulation between them, that is, to improve the heat resistance.

[0005] However, the above-mentioned demands for improving the electrochemical characteristics by increasing the concentration of the electrolytic solution and improving the film strength including heat resistance are generally contradictory, and a polymer compatible with these requirements is required. Obtaining a gel electrolyte is not easy.

In order to provide a polymer gel electrolyte having improved properties as described above, an electrolytic solution is applied to a composite matrix resin containing a vinylidene fluoride polymer having excellent electrochemical properties and a crosslinked polymer as main components. Some attempts have been made to form a polymer gel electrolyte by impregnation and holding as follows.

(A) A solution of a vinylidene fluoride polymer dissolved in a mixture of an organic solvent such as THF (tetrahydrofuran) and a volatile organic solvent having the ability to dissolve the vinylidene fluoride polymer. After dissolving a polyfunctional monomer having a functional group and a carboxyl group-containing monomer, casting the resulting solution, and evaporating THF, the monomers in the film-like material obtained are cross-linked and polymerized to form a polymer gel electrolyte. Method for obtaining (Japanese Patent Application Laid-Open No. 11-185524). It is intended that the polymer of the carboxyl group-containing monomer maintain the electrolyte at a high concentration.

(B) The vinylidene fluoride polymer swollen with the electrolytic solution is obtained by dissolving the polyfunctional monomer in a dispersion of the vinylidene fluoride polymer in the electrolytic solution and crosslinking-polymerizing the polyfunctional monomer. A method for obtaining a polymer gel electrolyte held by the formed crosslinked polymer (JP-A-11-0866)
No. 30).

[0009] However, the content of the electrolyte solution in the polymer gel electrolyte realized by these methods is about 60 to 80% by weight, and it is still difficult to say that it is sufficient from the viewpoint of improving the ionic conductivity. According to the study of the present inventors, as will be described later in more detail in connection with the present invention, the above method employs a system in which a vinylidene fluoride polymer swells but does not dissolve in an electrolytic solution alone. Therefore, it is understood that the improvement of the content of the electrolytic solution is insufficient. In fact, vinylidene fluoride polymer has been used as an excellent positive electrode or negative electrode binder in conventional non-aqueous batteries that use an electrolyte as an ion-conducting medium, mainly because of its electrochemical stability, Swells but does not dissolve due to the excellent electrolyte resistance properties, but the present inventors have found that such electrolyte resistance properties of vinylidene fluoride polymers are not necessarily advantageous for the formation of polymer gel electrolytes. I found that.

[0010]

That is, a main object of the present invention is to provide a polymer gel electrolyte which can hold an electrolyte at a high concentration and has a high ionic conductivity.

Another object of the present invention is to provide a non-aqueous battery containing the polymer gel electrolyte, an efficient method for producing the same, and a precursor composition for forming the polymer gel electrolyte.

[0012]

According to the study of the present inventors, in order to achieve the above object, a combination in which an electrolyte solution (electrolyte solution) and a vinylidene fluoride polymer have compatibility is adopted. Has been found to be highly desirable.

The polymer gel electrolyte of the present invention is based on the above-mentioned findings, and the electrolyte solution (I) obtained by dissolving an ionic compound in an organic solvent can be dissolved at least (a) alone in the electrolyte solution. A matrix resin (I) comprising a type and amount of a vinylidene fluoride polymer and (b) a crosslinked polymer of a polyfunctional monomer having two or more functional groups.
I), characterized by being fixed by: In the polymer gel electrolyte of the present invention, preferably 80 to
A high electrolyte solution content of 99% by weight is obtained. Preferably, the polymer gel electrolyte is obtained by cross-linking and polymerizing a polyfunctional monomer in an electrolyte solution (I) in which a vinylidene fluoride polymer (a) is dissolved. In order to improve the mutual solubility between the vinylidene fluoride polymer (a) and the electrolyte solution (I), heating is more preferably performed.

As can be understood from the above-mentioned production method, the matrix resin forming the polymer gel electrolyte of the present invention comprises:
A so-called interpenetrating polymer network structure in which the polymer networks of both the vinylidene fluoride polymer (a) and the crosslinked polymer of the formed polyfunctional monomer (b) are entangled with each other at the molecular level.
networks; hereinafter, may be referred to as an “IPN structure”. However, in the IPN structure, it is normal that no chemical bond occurs between the constituent two polymer chains. However, in the present invention, the chemical bond between the vinylidene fluoride polymer (a) and the crosslinked polymer (b) is used. May be present). It can be understood that the favorable IPN structure between the vinylidene fluoride polymer (a) and the crosslinked polymer (b) expresses the high-concentration retention characteristics of the electrolytic solution. In contrast, Japanese Patent Laid-Open No.
According to the method disclosed in Japanese Patent Application Laid-Open No. 1-086630, the vinylidene fluoride polymer is swollen in the electrolytic solution, but the cross-linking polymerization of the polyfunctional monomer is performed in a state where the polymer is not dissolved. It is understood that since no is formed, the electrolyte retention characteristics are insufficient, and the non-uniform gel lacks the uniform conductivity of ions. On the other hand, according to the method disclosed in JP-A-11-185524, it is understood that a tentative IPN structure is formed between the vinylidene fluoride polymer, the crosslinked polymer, and the polymer of the carboxyl group-containing monomer. However, it is understood that during the evaporation of the volatile organic solvent used in a large amount, the formation of an IPN structure that exhibits good electrolyte retention characteristics may be hindered. Further, in the present invention, since the vinylidene fluoride polymer (a) and the electrolyte solution (I) employ a combination having a high affinity to the extent that mutual solubility is exhibited, this is also the electrolyte solution retention characteristic of the IPN structure. It is understood that has improved.

A non-aqueous battery according to the present invention is characterized in that the polymer gel electrolyte of the present invention is disposed between a positive electrode and a negative electrode.

Further, the method for producing a non-aqueous battery according to the present invention comprises:
This corresponds to an efficient method for producing the above non-aqueous battery, and comprises dissolving a vinylidene fluoride polymer (a), a polyfunctional monomer, and a polymerization initiator of the polyfunctional monomer in an electrolyte solution (I). A step of injecting the resulting solution between the positive electrode and the negative electrode of the package housing the positive electrode and the negative electrode, and then heating the package to gel the solution.

Further, the composition for injecting and forming a polymer gel electrolyte of the present invention corresponds to a precursor composition for forming a polymer gel electrolyte which enables the above-mentioned method for producing a nonaqueous battery to be efficiently carried out. And a vinylidene fluoride polymer (a)
And a solution obtained by dissolving a polyfunctional monomer and a polymerization initiator of the polyfunctional monomer in an electrolyte solution (I).

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (I) Electrolyte solution The first component quantitatively constituting the polymer gel electrolyte of the present invention is an electrolyte solution (electrolyte solution), which dissolves an ionic compound in an organic solvent. It is obtained by doing.

[0019] (i) an ionic compound used in the ionic compound present invention, in a non-aqueous battery including a lithium ion battery, which is used as an electrolyte, the general formula M ⁺ X ^- (M ⁺ Periodic The ion of a metal belonging to Group I or Group II in the table, X ⁻ is preferably an anion) is preferable. Especially M ⁺ is Li ^+, LiP Specific examples of preferably those selected from Na ⁺ or K ^+, more preferred ionic compounds
F ₆ , LiAsF ₆ , LiClO ₄ , LiBF ₄ , LiC
1, LiBr, LiCH ₃ SO ₃ , LiCF ₃ SO ₃ , Li
_{N (CF 3 SO 2) 2} , LiC (CF 3 SO 2) 3, can be mentioned.

(Ii) Organic Solvent In the present invention, in addition to the above-mentioned ionic compound, an organic solvent having a high solubility for a vinylidene fluoride polymer described later is used as the organic solvent constituting the electrolyte solution together with the ionic compound. by it is preferred, it is further meant to ensure the electrochemical stability required for use in non-aqueous battery, HOMO (highest occupied molecular orbital energy) by ab initio method level is -11eV less Excellent oxidation resistance and LUMO (lowest vacancy molecular orbital energy level) of +4.0 eV or more, especially +
An organic solvent having an excellent reduction resistance represented by being 4.5 eV or more is preferable.

The HOMO level and the LUMO level of the solvent can be calculated by molecular orbital calculation (ab initio method) using a commercially available program. (Note that the values described in this specification are those of Carnegie Office Park Bu.
ilding 6, Pittsburgh, PA151
06 U.S. S. A. Gaussi (United States)
an, Inc. Commercial general-purpose program "G
aussian 94 "and the basis set 3-21G
^(*) Is based on the value calculated by the present inventors. )
HOMO level is -12 eV or less and LUMO level is +
Specific examples of the organic solvent of 4.0 eV or more include acetonitrile (HOMO-12.62 eV, LUMO +
5.97 eV), ethylene-carbonate (HOMO-
12.46 eV, LUMO + 5.87 eV), dimethyl carbonate (HOMO-12.21 eV, LUMO +
6.10 eV), diethyl carbonate (HOMO-1
2.08 eV, LUMO + 6.22 eV), ethyl methyl carbonate (HOMO-12.14 eV, LUMO
+6.16 eV), propylene carbonate (HOMO
-12.34 eV, LUMO + 5.88 eV), propionitrile (HOMO-12.42 eV, LUMO +
5.76 eV), butylene carbonate (HOMO-1)
2.31 eV, LUMO + 5.87 eV), γ-butyrolactone (HOMO-11.50 eV, LUMO + 5.
06 eV) and the like, but are not limited to the above.

For reference, a solvent conventionally used as a solvent for a vinylidene fluoride polymer for forming an electrode binder solution is, for example, N-methylpyrrolidone (H
OMO-10.18 eV, LUMO + 5.81 eV),
N, N-dimethylformamide (-9.85 eV, +
5.80 eV), acetone (-10.93 eV, +4.
53 eV), N, N-dimethylacetamide (-9.6
6 eV, +5.67 eV), toluene (−8.88 e)
V, +2.87 eV), dimethyl phthalate (-9.70)
eV, +1.74 eV), 1,4-dioxane (-1
0.36 eV, +7.39 eV), tetrahydrofuran (-10.79 eV, +6.93 eV), etc., all of which do not mainly satisfy the requirement that the HOMO level is −11 eV or less. This is not preferred for the purpose of the present invention.

In order to form the polymer gel electrolyte of the present invention, for example, acetone, THF which has been conventionally used as a good solvent or a latent solvent for a vinylidene fluoride polymer is used.
It is desirable not to employ a step of dissolving the vinylidene fluoride polymer using a volatile organic solvent having a boiling point of 100 ° C. or lower, and evaporating and removing the organic solvent. This not only simplifies the manufacturing process but also keeps the electrolyte content in the polymer gel electrolyte high, and furthermore, dimethyl carbonate (boiling point 90-91 ° C), diethyl carbonate (boiling point 127 ° C), ethyl It has good electrochemical properties such as methyl carbonate (boiling point, 108 ° C.) and is suitable for preparing a low-viscosity electrolytic solution. And good composition control becomes possible. That is, it is preferable that substantially the entire amount of the organic solvent used to form the electrolyte solution (I) constituting the polymer gel electrolyte of the present invention is incorporated into the polymer gel electrolyte.

It is also preferable to adjust the dissolving ability of the vinylidene fluoride polymer by mixing two or more kinds of organic solvents.
The ionic compound is contained in an amount of 0.1 to 1 liter.
It is preferable to form the electrolyte solution (I) by dissolving at a ratio of 10 to 10 mol, particularly 0.5 to 5 mol.

(II) Matrix resin The polymer gel electrolyte of the present invention comprises the above-mentioned electrolyte solution (I)
Is held and fixed with the matrix resin (II). The matrix resin (II) comprises at least a vinylidene fluoride polymer (a) and a crosslinked polymer of a polyfunctional monomer (b).

(A) Vinylidene Fluoride Polymer As the vinylidene fluoride polymer (a) used in the present invention, a homopolymer of vinylidene fluoride or a vinylidene fluoride of 50% by weight or more and a copolymer copolymerizable therewith can be used. A copolymer having a monomer content of 1% by weight or more is used. From the viewpoint of solubility in the electrolyte solution, a copolymer having a vinylidene fluoride content of 60 to 95% by weight is particularly preferably used. (However, a vinylidene fluoride homopolymer is also used by adjusting the inherent viscosity and using heating in combination, as described later.) Examples of monomers copolymerizable with the vinylidene fluoride monomer include ethylene, propylene, and the like. Hydrocarbon monomers, vinyl fluoride, ethylene trifluoride, ethylene trifluoride chloride, ethylene tetrafluoride, fluorinated monomers such as hexafluoropropylene, fluoroalkyl vinyl ether, etc., monomethyl maleate, citraconic acid Examples include carboxyl group-containing monomers such as monomethyl, and epoxy group-containing vinyl monomers such as allyl glycidyl ether and glycidyl crotonate, but are not necessarily limited thereto. Among them, vinylidene fluoride copolymers containing propylene hexafluoride and ethylene trifluoride chloride are preferably used.

The vinylidene fluoride polymer is at least 100 ° C. or less, preferably 80 ° C. or less, based on the electrolyte solution.
It is necessary to be soluble by heating at a temperature of not more than 0 ° C., and from this viewpoint, the inherent viscosity is not more than 2.5 dl / g, and further, 2.
It is preferably 2 dl / g, especially 2.0 dl / g or less. From the viewpoint of the mechanical strength and heat resistance of the obtained polymer gel electrolyte, 0.2 dl / g or more, particularly 0.4 dl / g or more.
/ G or more. Here, the inherent viscosity is used as a measure of the molecular weight of the polymer, and refers to the logarithmic viscosity at 30 ° C. of a solution obtained by dissolving 4 g of a resin in 1 liter of N, N-dimethylformamide.

The vinylidene fluoride polymer (a) is soluble in the above-mentioned electrolyte solution at least under heating, and the electrolyte solution is combined with a cross-linked polymer (b) of a polyfunctional monomer to be described later. It is necessary to constitute a matrix resin (II) for forming a heat-resistant polymer gel electrolyte, which is stably maintained at a high concentration, is electrochemically stable, and is at least autonomous, and has a high heat resistance. 1 to 10 parts by weight, especially 1 to 100 parts by weight of (I)
It is preferably used in a proportion of 7 parts by weight.

(B) Crosslinked Polymer of Polyfunctional Monomer Along with the vinylidene fluoride polymer (a), the crosslinked polymer (a) constituting the matrix resin is obtained by crosslinking polymerization of a polyfunctional monomer. The polyfunctional monomer has two or more polymerizable functional groups, and as the polymerizable functional group, a vinyl group, particularly an acryloyl group (including a vinyl group) is preferable. Specific examples of the polyfunctional monomer include dimethylol tricyclodecane diacrylate, divinylbenzene, ethylene glycol dimethacrylate,
Triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, 1,3-dimethacrylate
Butyl glycol, propylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6
-Hexanediol dimethacrylate, neopentyl glycol dimethacrylate, allyl methacrylate, allyl acrylate, bisphenol dimethacrylate, bisphenol diacrylate, cycloaliphatic diacrylate, diacrylated isocyanurate, trimethylolpropane trimethacrylate, triacryl Formal,
Triacryl isocyanurate, triallyl cyanurate, aliphatic triacrylate, pentaerythritol tetramethacrylate, pentaerythritol tetraacrylate, aliphatic tetraacrylate, and the like are preferably used, but are not limited thereto. .

The polyfunctional monomer is dissolved in a solution of the vinylidene fluoride polymer (a) in the electrolyte solution (I), and is heated, irradiated with visible or ultraviolet light, irradiated with an electron beam or γ-ray. Cross-linking polymerization is carried out by the method described above. If necessary, a polymerization initiator can be added. As the thermal polymerization initiator, various organic peroxides can be used, such as dialkyl peroxides such as di-t-butyl peroxide, diacyl peroxides such as benzoyl peroxide, and 2,5-dimethyl-dioxide. Peroxyketals such as (t-butylperoxy) hexane, di-i-propylperoxydicarbonates, and the like are suitably used, and azobisisobutyronitrile and the like can also be suitably used.

As the photopolymerization initiator, dimethoxyphenylacetophenone, 2-hydroxycyclohexylphenylketone, 2-hydroxy-2-methyl-1-phenylpropanone-1,1- (4-isopropylphenyl)
2-Hydroxy-2-methylpropanone-1 and the like are preferably used.

One of the preferable methods for forming the polymer gel electrolyte of the present invention is a composition before cross-linking polymerization to which the above-mentioned polymerization initiator is added, that is, a vinylidene fluoride polymer (a), a polyfunctional monomer, A solution obtained by dissolving the polymerization initiator of the polyfunctional monomer and the electrolyte solution (I) is injected between the positive electrode and the negative electrode of an exterior body containing the positive electrode and the negative electrode constituting the nonaqueous battery, and thereafter, Heat the outer body,
By gelling the solution, a polymer gel electrolyte is formed in situ. Thereby, the main part of the non-aqueous battery is formed at once. That is, the process of forming the battery after forming the polymer gel electrolyte layer and laminating it with the positive electrode layer and the negative electrode layer is remarkably simplified.

The thermal polymerization initiator added to the precursor composition for this purpose is preferably one that enables cross-linking polymerization at a temperature of about 30 to 80 ° C. It is preferable to use 0.01 to 30 parts by weight with respect to parts by weight.

The total amount of the crosslinked polymer (b) thus formed and the vinylidene fluoride polymer (a) (that is, the amount of the matrix resin (II)) is the same as that of the polymer gel electrolyte of the present invention. It is preferable that the amount occupies 1 to 20% by weight, more preferably 2 to 15% by weight, particularly preferably 2 to 10% by weight. If the proportion is less than 1% by weight, the necessary independence and heat resistance of the polymer gel electrolyte may not be obtained. If the proportion exceeds 20% by weight, the effect of improving the ionic conductivity is poor and the homogeneity is poor. There is a possibility that the solution state of the precursor composition may be impaired even under heating, and the homogeneity of the obtained IPN structure may be impaired.

The vinylidene fluoride polymer (a) and the crosslinked polymer (b) in the matrix resin (II)
The proportion of the vinylidene fluoride polymer (a) to the total amount of is 10 to 90% by weight, further 10 to 80% by weight,
In particular, it is preferably in the range of 20 to 75% by weight.
If this proportion is less than 10% by weight, the electrochemical properties of the resulting polymer gel electrolyte, particularly the ionic conductivity, may be reduced, and a gel with high elasticity may not be obtained. On the other hand, if it exceeds 90% by weight, the strength (self-supporting) and heat resistance of the polymer gel electrolyte tend to be insufficient.

The basic structure of the non-aqueous battery of the present invention can be obtained by disposing the polymer gel electrolyte layer obtained as described above between the positive electrode and the negative electrode. The thickness of the polymer gel electrolyte layer is preferably from 2 to 1000 μm, particularly preferably from about 5 to 200 μm.

In the case where the configuration as a lithium ion battery is taken as an example of a non-aqueous battery, as a positive electrode active material, for example, a general formula LiMY ₂ (M is Co, Ni, F
e, at least one of transition metals such as Mn, Cr, V: Y
Is a complex metal chalcogen compound represented by a chalcogen element such as O and S, particularly LiNi _x Co _{1 -x} O ₂ (0 ≦ x ≦
A composite metal oxide having a spinel structure such as 1) or a composite metal oxide such as LiMn ₂ O ₄ is preferably used.

The above-mentioned basic structure of the laminated battery is further laminated as necessary by winding or folding, so as to increase the electrode area per volume, and further accommodate the electrode in a relatively simple container. For example, a non-aqueous battery having an overall structure such as a prismatic shape, a cylindrical shape, a coin shape, a paper shape, or the like is formed. However, as described above, it is most preferable that the polymer gel electrolyte is formed by crosslinking polymerization after being injected into the non-aqueous battery outer package.

The polymer gel electrolyte of the present invention can be used for electrochemical devices such as electric double layer capacitors, electrochromic displays, and sensors, in addition to the above-mentioned lithium ion secondary battery, by utilizing its excellent characteristics.

[0040]

The present invention will be described more specifically with reference to the following examples and comparative examples. First, a preparation example of a vinylidene fluoride polymer will be described.

(Preparation Example of Polymer-1) Content 10 L
8013 parts by weight of ion-exchanged water in an autoclave
(G), 1.565 parts by weight of methylcellulose, Freon 2
25cb 25.04 parts by weight of ethyl acetate 93.9 wt
Part, diisopropyl peroxydicarbonate (IP
P) 25.04 parts by weight, vinylidene fluoride (VdF) 2
442 parts by weight, propylene hexafluoride (HFP) 689
The suspension polymerization was carried out at 28 ° C. for 13 hours and 45 minutes.
Was. After the polymerization is completed, the polymer slurry is dehydrated, washed with water, and then dried.
It dried at 20 degreeC for 20 hours, and obtained the polymer powder A. The conversion is 6
At 3%, the resulting inherent viscosity (η_{in h}) Is 0.8
It was 17 dl / g.¹⁹As a result of F-NMR analysis, polymerization
Vinylidene fluoride monomer and propylene hexafluoride
The polymerization ratio of the monomer was 87:13.

(Polymer Preparation Example-2) In an autoclave having a content of 2 liters, 1075 parts by weight of ion-exchanged water, 0.21 parts by weight of methylcellulose, 225 cb of CFCs
4.2 parts by weight, ethyl acetate 12.6 parts by weight, diisopropyl peroxydicarbonate (IPP) 4.2 parts by weight, vinylidene fluoride (VdF) 344.4 parts by weight, 6
42 parts by weight of propylene fluoride (HFP) and 8 parts by weight of trifluorinated ethylene chloride (CTFE) were charged, and the mixture was heated at 29 ° C to 26 parts by weight.
Suspension polymerization was performed for 30 minutes. After completion of the polymerization, the polymer slurry was dehydrated, washed with water, and dried at 80 ° C. for 20 hours to obtain a polymer powder B. The conversion was 90%, and the obtained η _inh was 0.836 dl / g. As a result of ¹⁹ F-NMR analysis, the polymerization ratio of the vinylidene fluoride monomer, propylene hexafluoride and ethylene trifluoride in the polymer was 8%.
3: 8: 9.

(Polymer Preparation Example-3 to 5) Polymer Preparation Example-
Polymerization was carried out in the same manner as in Example 2 except that the polymerization conditions such as the monomer composition and ratio were changed. Table 1 summarizes the polymerization conditions and the properties of the obtained polymer.

[0044]

[Table 1]

(Analytical Method of ¹⁹ F-NMR Analysis) The vinylidene fluoride polymer was determined from the diffraction peak of the analytical spectrum of ¹⁹ F-NMR analysis.

Specifically, about 5 mg of a vinylidene fluoride-based polymer sample was placed in dimethylformamide (DMF) 0.4
ml deuterium dimethylformamide is an NMR measurement solvent (DMF-d ₇₎ was dissolved in a mixed solvent of 0.1 ml,
¹⁹ F-NMR was measured at room temperature.

(Measurement Method of Inherent Viscosity)
80 mg of N, N-dimethylformamide
In a 30 ° C thermostat using an Ubbeloth viscometer
Inherent viscosity η is given by_{in h}Was found: η_inh= (1 / C) · ln (η / η_oHere, η is the viscosity of the polymer solution, η_oIs N, N-
The viscosity of dimethylformamide alone, C is 0.4 (g / d
l).

<Example 1> 1 part by weight of the polymer powder A obtained in Preparation Example 1 was weighed in a 50 ml closed container, and an electrolytic solution (ethylene carbonate (EC) / propylene carbonate (PC) / diethylene Carbonate (DEC)
= 100 parts by weight (10 g) in a mixed solution (1/1 (volume ratio) of LiPF ₆ dissolved at 1 molar concentration) at 60 ° C.
, And allowed to cool to room temperature.

To the solution, 3 parts by weight of tetramethylolmethanetetraacrylate (A-TMMT) was added, and the mixture was stirred at room temperature for several minutes. Then, 0.5 parts by weight of isopropyl peroxydicarbonate (IPP) was added, and the mixture was heated at 60 ° C. for 1 hour. Polymerized for hours.

The elasticity of the obtained polymer was confirmed by lightly pressing with a spatula or the like under visual observation at room temperature. Further, the same polymer was used at 80 ° C. for 1 hour and 10 hours.
Heat treatment was performed at 0 ° C. for 1 hour, and the heat resistance was evaluated based on the presence or absence of collapse of the polymer (gel).

As a result, according to the above-mentioned example, an elastic gel was obtained, and heat resistance without gel collapse was shown by any heat treatment.

Examples 2 to 10 Except that the amount of vinylidene fluoride polymer powder A and the amount of polyfunctional monomer (tetramethylolmethanetetraacrylate (A-TMMT)) were changed as shown in Table 2 below, A polymer (gel) was obtained and evaluated in the same manner as in Example 1. As a result, in each case, the same result as in Example 1 was obtained.

Comparative Example 1 Polymerization was attempted in the same manner as in Example 1 except that vinylidene fluoride polymer powder A was not used and A-TMMT was used in an amount of 2 parts by weight.

As a result, no gelled polymer was obtained.

<Comparative Example 2> A polymer was obtained and evaluated in the same manner as in Example 1 except that vinylidene fluoride polymer powder A was not used and A-TMMT was used in an amount of 6 parts by weight.

As a result, an elastic gel polymer could not be obtained, and a solidified product having no elasticity was obtained.

<Embodiment 11> The same electrolytic solution (E
LiPF _{6 to} C / PC / DEC = 1/1/2 (volume ratio)
Was dissolved at a molar concentration of 100 parts by weight, and 2 parts by weight of the polymer powder and methacrylate monomer (trade name “4
G "(manufactured by Shin-Nakamura Chemical Co., Ltd .; abbreviated as" MM4G ") except that 9 parts by weight were used to obtain and evaluate a polymer (gel) in the same manner as in Example 1. As a result, the same result as in Example 1 was obtained.

<Example 12> Methacrylate monomer
Instead of (MM4G), methacrylate monomer; give (trade name "9PG", manufactured by Shin-Nakamura Chemical Co., Ltd. "MM9PG" for short) in the same manner as in Example 1 except for using polymerization product (gel) was evaluated . As a result, the same result as in Example 1 was obtained.

<Examples 13 to 21> A-TMMT using 1 to 3 parts by weight of vinylidene fluoride polymer powders A, B and C
Was fixed to 3 parts by weight, and a polymer (gel) was obtained and evaluated in the same manner as in Example 1 except that the composition changed as shown in Table 2.
As a result, in each case, the same result as in Example 1 was obtained.

Example 22 In a 50 ml closed container,
6.7 parts by weight of the polymer powder F was weighed, heated and dissolved at 60 ° C. using 100 parts by weight (4.5 g) of the same electrolytic solution as in Example 1, and then cooled to room temperature.

Next, the same polyfunctional monomer (A
After adding 2.2 parts by weight of (TMMT) and stirring at room temperature for several minutes, 1.1 parts by weight of IPP was added and polymerization was carried out at 50 ° C. for 1 hour.

The obtained polymer was an elastic gel, and showed no heat collapse at 60 ° C. for 1 hour, although no gel collapse was observed by heat treatment at 50 ° C. for 1 hour. After, fluidity was observed.

[0063]

[Table 2]

Including the above examples, the electrolytic solution (E
LiPF _{6 to} C / PC / DEC = 1/1/2 (volume ratio)
Is dissolved at a molar concentration of 100 parts by weight), and a polymer is prepared by adding a variable amount of the polymer powder A and a polyfunctional monomer (tetramethylolpropanetetraacrylate (A-TMMT)) to the polymer. It is summarized as in Table 3.

[0065]

[Table 3]

<Example 23> 2 parts by weight of the polymer powder D was mixed with the same electrolytic solution (EC / PC / DEC = 1 /
Dissolve LiPF ₆ at a molar concentration of 1/2 (volume ratio) 1
After heating and dissolving in 00 parts by weight at 60 ° C., the mixture was naturally cooled to room temperature. Next, 3 parts by weight of 2-methacryloyloxy isocyanate (MEI) having an unsaturated double bond and 1 part by weight of dibutyltin dilaurate as a catalyst were added and reacted at 70 ° C. for 1 hour. From the IR measurement results, it was confirmed that the carboxylic acid of the polymer D and the isocyanate (-N = C = O) had reacted.

A-TMMT (3 parts by weight) was added thereto, and the mixture was stirred at room temperature for several minutes.
Polymerization was performed at 0 ° C. for 1 hour. The obtained polymer was an elastic gel and was subjected to a heat resistance test (80 ° C. × 1) as in Example 1.
h, 100 ° C. × 1 h), it was found that the gel did not disintegrate and was excellent in heat resistance.

<Example 24> Polymer powder D of Example 23
Was replaced by a polymer powder E, and an electrolytic solution (EC / PC
/ DEC = 1/1/2 (volume ratio) 1M LiPF ₆ ) 10
Instead of 0 parts by weight, an electrolytic solution (γ-butyrolactone is added to Li
Except that the PF ₆ with 1 dissolved at a molar concentration) 100 parts by weight in the same manner as in Example 23, to obtain a polymer.

As a result, the obtained polymer was an elastic gel, and was subjected to a heat resistance test (80 ° C. × 1) in the same manner as in Example 1.
h, 100 ° C. × 1 h), it was found that the gel did not disintegrate and was excellent in heat resistance.

[0070] In <Comparative Example 3> in a sealed container of 50ml,
When 12.5 parts by weight of the polymer powder A and 100 parts by weight (8 g) of an electrolytic solution (1 mol of LiBF ₄ dissolved in γ-butyrolactone) were stirred at room temperature for 15 minutes, the polymer powder A swelled. Did not dissolve.

Next, polyoxyethylene (n = 23)
After adding 12.5 parts by weight of dimethacrylate (molecular weight 1136) and stirring for several minutes, 1.25 parts by weight of IPP was added and polymerization was carried out at 60 ° C. for 1 hour.

It was observed that the polymer was separated into a thin upper gel which was almost colorless and transparent, and a lower turbid lower gel containing the polymer powder A, and the gel itself had elasticity.

Examples 4, 11, 12,
23 and Reference Example 1 (only the electrolyte of the above example) and Example 24 and Reference Example 2 (only the electrolyte of the above Example 24), and further using the gel raw material or the electrolyte of Comparative Example 3, the following The ionic conductivity was measured as described above.

<Measurement of Ionic Conductivity> That is, only the liquid precursor before the cross-linking polymerization in each example or the electrolytic solution alone was placed in a cell made of SUS and polymerized in an oven at 60 ° C. for 1 hour. The impedance of this cell was measured by Cole-Cole plot. As a measuring device, a Solartron impedance analyzer / potentiometer was used. The frequency range was 1 kHz to
Was 100kHz.

The results are shown in Table 4 below.

[0076]

[Table 4]

[0077] In an embodiment of the present invention is much higher than the 1 ms / cm before and after the ion conductivity that is realized in a conventional polymer gel electrolyte, electrolyte solution alone (Reference Examples 1 and 2) both compared It is noted that ionic conductivity as high as possible is obtained.

[Evaluation of Battery Performance] (Preparation of Negative Electrode) Vinylidene fluoride polymer KF # 91
0.8 g of carbon material MCMB2
5-28 (manufactured by Osaka Gas Chemicals) and 9.2 g of N-methyl-2-pyrrolidone. The obtained slurry was applied on a copper foil having a thickness of 10 μm, dried at 130 ° C., and after removing N-methyl-2-pyrrolidone by evaporation, punched into a disk having a diameter of 15 mm and having a thickness of about 120 μm.
m dried electrodes were obtained.

(Preparation of Positive Electrode) 0.3 g of vinylidene fluoride polymer KF # 1300 (manufactured by Kureha Chemical Industry Co., Ltd.)
The mixture was mixed with 9.4 g of oO ₂ , 0.3 g of Denka Black HS-100 (manufactured by Denki Kagaku Kogyo) and 4.7 g of N-methyl-2-pyrrolidone. The obtained slurry is 10 μm thick.
Was dried at 130 ° C. to remove N-methyl-2-pyrrolidone by evaporation, and then punched into a disk having a diameter of 14 mm to obtain a dry electrode having a thickness of about 110 μm.

(Preparation Example of Gel Precursor Solution) <Example 25> In a 50 ml airtight container, 2 parts by weight of the polymer powder A obtained in Preparation Example-1 was weighed, and an electrolytic solution (ethylene carbonate (EC) / Ethyl methyl carbonate (EMC) = 1/1 (weight ratio) LiPF ₆
Was dissolved in 100 mol parts (10 g) by heating and then allowed to cool naturally to room temperature.

[0081] 3 parts by weight of tetramethylolmethanetetraacrylate (A-TMMT) was added thereto, and the mixture was stirred at room temperature for several minutes, and then 0.5 parts by weight of isopropyl peroxydicarbonate (IPP) was added thereto to obtain a gel precursor solution. Was prepared.

(Preparation and Evaluation of Battery) <Example 26> An electrode structure was formed by sandwiching a polypropylene separator (thickness: 20 μm) between the positive electrode and the negative electrode prepared above, and was placed in a stainless steel can. The battery was charged to form a coin-shaped battery can. After injecting the gel precursor solution prepared in Example 25 there, the stainless steel can was caulked, and then a crosslinking reaction was allowed to proceed at 60 ° C. for 1 hour to produce a gel electrolyte battery. After charging to 4.0 V at 0.4 mA at 25 ° C., charging was continued at a constant voltage for 25 hours, and then 3.0 V at a constant current of 0.4 mA.
After performing one charge-discharge cycle, the battery was charged to 4.0 V at 4.0 mA from the second time,
To continue charging time constant voltage, it was repeated cycle 31 times for charging and discharging discharged to 3.0V at a subsequent 3.0mA constant current. The value obtained by dividing the 31st discharge capacity by the 2nd discharge capacity was multiplied by 100 to obtain a capacity retention (%). The results are shown in Table 5 below.

<Comparative Example 4> In Example 26, an electrolyte (ethylene carbonate (EC) / ethyl methyl carbonate (EMC)) was used instead of the solution prepared in Example 25.
= 1/1 (weight ratio) LiPF ₆ dissolved at a 1 molar concentration in a mixed solution) was injected into a coin-type battery can body,
A battery was prepared and charged and discharged in the same manner as in Example 26, except that heating was not performed for a period of time, and the 31st capacity retention was measured in the same manner. The results are shown in Table 5 below.

[0084]

[Table 5]

From the above table, it was found that the battery performance using the polymer gel electrolyte according to the present invention showed a high capacity retention as in the case of using the battery consisting of only the electrolyte solution of Comparative Example 4.

[0086]

As described above, according to the present invention, in a system using an organic solvent in which an electrolyte solution and a vinylidene fluoride polymer are compatible and substantially all of which is contained in a polymer gel electrolyte, By cross-linking and polymerizing polyfunctional monomers,
The high concentration of the electrolyte solution in the uniform IPN structure composed of the vinylidene fluoride polymer and the crosslinked polymer provides a polymer gel electrolyte having extremely high ionic conductivity. Further, by using the precursor composition before the cross-linking polymerization, a high-performance non-aqueous battery and its efficient production become possible.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C08K 5/00 C08K 5/00 C08L 27/16 C08L 27/16 33/04 33/04 H01B 1/06 H01B 1/06 A (72) Inventor Tomoaki Kawakami 16-1--4-5 Maehara, Nishikicho, Iwaki-shi, Fukushima F-term (reference) 4J002 BD14W BG04X BG05X BG07X DD036 DD056 DD086 DE196 DH006 DK006 EV256 EV266 EZ006 GQ02 4J011 PA07 PA10 PA14 PA45 PA66 PC02 PC08 4J026 AA26 BA07 BA28 BA29 DB02 DB09 DB12 DB15 DB36 FA04 FA09 GA06 5G301 CA30 CD01 5H029 AJ01 AK03 AL06 AM03 AM04 AM05 AM07 BJ03 BJ16 CJ11 EJ12 HJ01 HJ10 HJ14

Claims (11)

[Claims] 1. An electrolyte solution (I) in which an ionic compound is dissolved in an organic solvent, at least (a) a vinylidene fluoride polymer of a kind and in an amount capable of being dissolved in the electrolyte solution alone; A polymer gel electrolyte characterized by being fixed with a matrix resin (II) comprising a crosslinked polymer of a polyfunctional monomer having a functional group. 2. The content of the electrolyte solution is 80 to 99% by weight.
The polymer gel electrolyte according to claim 1, which is: 3. Constituting a matrix resin (II),
The ratio of the vinylidene fluoride polymer (a) to the total weight of the vinylidene fluoride polymer (a) and the crosslinked polymer (b) of the polyfunctional monomer is 10 to 90% by weight according to claim 1 or 2. Polymer gel electrolyte. 4. The vinylidene fluoride polymer (a) has an inherent viscosity of 0.2 to 2.5 dl / g.
4. The polymer gel electrolyte according to any one of 3. 5. The polymer gel electrolyte according to claim 1, wherein the vinylidene fluoride polymer (a) is a vinylidene fluoride polymer having a functional group. 6. The polymer gel electrolyte according to claim 1, which is non-flowable at least at 50 ° C. 7. The organic solvent constituting the electrolyte solution (I) is a HOMO by ab initio molecular orbital calculation.
The polymer gel electrolyte according to any one of claims 1 to 6, which is an organic solvent having a level of -11 eV or less and a LUMO level of +4.0 eV or more. 8. The polymer gel electrolyte according to claim 1, which is obtained by crosslinking and polymerizing a polyfunctional monomer in an electrolyte solution (I) in which a vinylidene fluoride polymer (a) is dissolved. . 9. A non-aqueous battery comprising the polymer gel electrolyte according to claim 1 disposed between a positive electrode and a negative electrode. 10. A housing for housing a positive electrode and a negative electrode, comprising a solution obtained by dissolving a vinylidene fluoride polymer (a), a polyfunctional monomer, and a polymerization initiator of the polyfunctional monomer in an electrolyte solution (I). Body, injected between the positive and negative electrodes,
The method for producing a non-aqueous battery according to claim 9, further comprising a step of heating the outer package to gel the solution. 11. A vinylidene fluoride polymer (a), a polyfunctional monomer, and a polymerization initiator of the polyfunctional monomer,
A polymer gel electrolyte injection-forming composition comprising a solution dissolved in an electrolyte solution (I).