JP3587982B2 - Polymer solid electrolyte and lithium secondary battery and electric double layer capacitor using the same - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a polymer solid electrolyte and a lithium secondary battery and an electric double layer capacitor using the same.
[0002]
[Prior art]
At present, various types of batteries are widely used from the field of electronics to automotive applications or large batteries intended for power storage.
[0003]
Normally, a liquid is used as the electrolyte of such a battery. However, if the electrolyte can be made solid, it is possible to prevent liquid leakage and to form a sheet. For this reason, batteries using solid electrolytes have attracted attention as next-generation batteries. In particular, if a lithium ion secondary battery or the like, which has been rapidly used in notebook personal computers, mobile phones, and the like, can be made into a sheet or miniaturized, it is expected that the range of application will be further expanded.
[0004]
When such a solid electrolyte is used, a ceramic material, a polymer material, or a composite material thereof has been proposed. Above all, gel electrolytes plasticized by using a polymer electrolyte and an electrolyte solution have both high liquid-based electrical conductivity and high polymer-based plasticity, and are thus expected to be promising in the development of electrolytes.
[0005]
An example in which a gel polymer solid electrolyte is used in a battery has already been disclosed, and a practical system is also proposed in US Pat. Nos. 5,296,318 and 5,418,091. Have been.
[0006]
Some of such gel-like polymer solid electrolytes (hereinafter, referred to as “gel electrolytes”) have a conductivity close to that of a liquid and exhibit a value of 10 ⁻³ S · cm ⁻¹ level.
[0007]
For example, US Pat. No. 5,296,318 discloses a copolymer of vinylidene fluoride (VDF) and 8 to 25% by weight of propylene hexafluoride (HFP) [P (VDF-HFP)]. A gel electrolyte containing 20 to 70% by weight of a solution in which a lithium salt is dissolved is disclosed. The conductivity of this gel electrolyte reaches 10 ⁻³ S · cm ⁻¹ .
[0008]
However, since such a gel electrolyte contains the same electrolytic solution as in the solution system, it has inherent problems such as leakage and volatilization, and lacks reliability. In addition, since it contains a similar flammable component, though not as much as a solution system, there is a problem in safety.
[0009]
Further, as an electrolyte, a polymer compound composite obtained by solidifying a room temperature molten salt with a polymer compound has been proposed.
[0010]
For example, it has been proposed to fix a complex of N-butylpyridinium halide and aluminum halide known as a room temperature molten salt with a polymer compound (Watanabe et al., JCS Chem. Commun.). , 929, 1993). However, aluminum halide has a problem of corrosion and is not suitable for use in a lithium secondary battery. There is also a problem with stability.
[0011]
JP-A-8-245828 discloses a polymer compound composite obtained by solidifying a room temperature molten salt comprising a mixture of an aliphatic quaternary ammonium salt of an organic carboxylic acid and a lithium salt with a polymer compound. . However, such materials also have safety issues because they contain flammable components. Furthermore, the ionic conductivity is 10 ⁻⁴ S · cm ⁻¹ or less, which is too low for practical use.
[0012]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION An object of the present invention is to provide a polymer solid electrolyte having higher reliability, higher safety, and higher conductivity without changing the process of a conventional gel electrolyte, and a lithium secondary battery and an electric double layer capacitor using the same. Is to do.
[0013]
[Means for Solving the Problems]
Based on the background described above, the present inventors have studied the type of room temperature molten salt and the means for practical use, and as a result, fixed molten salt by using a molten salt fluorine-based microporous membrane using imidazolium salt. It has been found that a converted electrolyte material can be produced.
[0014]
That is, the above object is achieved by the present invention described below.
(1) A polymer solid electrolyte containing an imidazolium salt and a lithium salt represented by the following general formula (I) in a matrix of a fluoropolymer compound,
A polymer solid electrolyte in which the fluorine-based polymer compound is formed into a microporous film using a plasticizer.
[0015]
Embedded image
[0016]
(In the general formula (I), R ₁ , R ₂ and R ₃ each represent an alkyl group or a hydrogen atom,
A ^- is (RSO _{2) 2} N ^- represents,
R represents a perfluoroalkyl group having 1 to 3 carbon atoms,
When a plurality of Rs are present, they may be the same or different. )
(2) The lithium salt is LiC (RSO ₂ ) ₃ , LiN (RSO ₂ ) ₂ , LiRSO ₃ ,
(R represents a perfluoroalkyl group having 1 to 3 carbon atoms,
When a plurality of Rs are present, they may be the same or different. )
The polymer solid electrolyte according to the above (1), which is at least one of LiBF ₄ , LiPF ₆ , LiAsF ₆ and LiClO ₄ .
(3) The polymer solid electrolyte according to the above (1) or (2), wherein the fluorine-based polymer compound is a homopolymer or a copolymer of vinylidene fluoride.
(4) The polymer solid electrolyte according to any one of the above (1) to (3), wherein a mixing ratio of the imidazolium salt to the lithium salt is 10: 1 to 1: 2 in molar ratio.
(5) A lithium secondary battery having the polymer solid electrolyte according to any one of (1) to (4).
(6) An electric double layer capacitor having the polymer solid electrolyte according to any of (1) to (4).
[0017]
[Action]
The solid polymer electrolyte of the present invention contains a room temperature molten salt composed of an imidazolium salt and a lithium salt in a matrix of a fluorine-based polymer compound.
[0018]
Since this polymer solid electrolyte does not contain a conventional electrolytic solution, that is, an organic solvent, there is no problem such as liquid leakage or volatilization, and high reliability and durability are provided. Further, there is no problem of corrosion as in the case of aluminum halide which is conventionally known as a component of a room temperature molten salt.
[0019]
Moreover, in addition to containing no flammable components, the molten salt using this imidazolium salt is more stable than other compounds. Therefore, the electrolyte is nonflammable and has high safety.
[0020]
Further, the electric conductivity of the polymer solid electrolyte of the present invention is 10 ⁻⁴ to 10 ⁻² S · cm ⁻¹ , which is equivalent to that of a conventional gel electrolyte, and a substance close to that of a liquid can be obtained.
[0021]
The present inventors have already proposed using a mixture of a polymer of an imidazolium derivative and a lithium salt (lithium bis (trifluoromethanesulfonimide)) as an electrolyte (Oct. 1997, Polymer Symposium). ). However, at present, this electrolyte has an ionic conductivity of about 10 ⁻⁴ S · cm ⁻¹ or less. For practical use in the future, a thin film or further improvement in conductivity is left as an issue. ing.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
The solid polymer electrolyte of the present invention contains an imidazolium salt and a lithium salt represented by the following general formula (I) in a matrix of a fluorine-based polymer compound.
[0023]
Embedded image
[0024]
In the general formula (I), R ₁ , R ₂ and R ₃ each represent an alkyl group or a hydrogen atom, and A ⁻ represents (RSO ₂ ) ₂ N ⁻ . R represents a C1-C3 perfluoroalkyl group, and when two or more R exist, they may be mutually the same or different.
[0025]
The imidazolium molten salt can very well impregnate the fluoropolymer compound. Therefore, a highly reliable and safer battery that does not contain a conventional electrolytic solution can be manufactured without changing the conventional gel electrolyte process. The molten salt using the imidazolium salt is more stable than other compounds. Therefore, it is nonflammable as an electrolyte and has high safety.
[0026]
First, the imidazolium salt used in the present invention will be described.
[0027]
In the general formula (I), R ₁ , R ₂ and R ₃ each represent an alkyl group or a hydrogen atom. The alkyl group preferably has 1 to 5 carbon atoms in total, particularly preferably 1 to 3 carbon atoms, and more preferably a methyl group or an ethyl group. The alkyl group may be linear or branched.
[0028]
It is preferable that at least one of R _{1 to} R ₃ is an alkyl group. In particular, it is preferable that R ₁ and R ₃ are alkyl groups, and R ₂ is a hydrogen atom. R _{1 to} R ₃ may be the same or different.
[0029]
A ^- is (RSO _{2) 2} N ^- it is. R represents a perfluoroalkyl group having 1 to 3 carbon atoms. R is preferably a perfluoromethyl group. When a plurality of Rs are present, they may be the same or different.
[0030]
As A ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ is particularly preferable.
[0031]
Hereinafter, specific examples of the imidazolium salt represented by the general formula (I) are shown, but the present invention is not limited thereto. In addition, Chemical Formula 4 is represented using the notation of the general formula (I) of Chemical Formula 3.
[0033]
Embedded image
[0036]
A so-called asymmetric imidazolium salt in which R ₁ and R ₃ are different is preferable because a molten salt can be easily synthesized.
[0037]
Imidazolium salts are described in S. Wilkes et al. , J. et al. Chem. Soc. Chem. Commun. , 965, 1992; R. Koch et al. , J. et al. Electrochem. Soc. 142 , L116, 1995; R. Koch et al. , J. et al. Electrochem. Soc. , 143 , 798, 1996 and the like.
[0038]
The solid polymer electrolyte of the present invention contains a lithium salt in a matrix of a fluoropolymer compound together with the imidazolium salt.
[0039]
As the lithium salt, LiC (RSO ₂ ) ₃ , LiN (RSO ₂ ) ₂ , LiRSO ₃ , LiBF ₄ , LiPF ₆ , LiAsF ₆ and LiClO ₄ are preferably used. R represents a perfluoroalkyl group having 1 to 3 carbon atoms. R is preferably a perfluoromethyl group. When a plurality of Rs are present, they may be the same or different.
[0040]
As the lithium salt, LiN (CF ₃ SO ₂ ) ₂ is particularly preferable.
[0041]
One lithium salt may be used alone, or two or more lithium salts may be used in combination. When two or more kinds are used in combination, the mixing ratio is arbitrary.
[0042]
The mixing ratio of the imidazolium salt and the lithium salt is preferably from 10: 1 to 1: 2, particularly preferably from 4: 1 to 1: 1 in molar ratio. If the amount of the imidazolium salt is larger than this, the melting point will be high and it will not be practical. If the amount of the lithium salt is smaller than this, the lithium ion conductivity is lowered, and it is not practical.
[0043]
The solid polymer electrolyte of the present invention is obtained by impregnating a fluoropolymer compound with an imidazolium salt and a lithium salt.
[0044]
The fluorine-based polymer compound is, for example, polyvinylidene fluoride (PVDF), a vinylidene fluoride-hexafluoropropylene copolymer, a vinylidene fluoride-ethylene chloride trifluoride (CTFE) copolymer [P (VDF-CTFE)] , Vinylidene fluoride-hexafluoropropylene fluororubber, vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene fluororubber [P (VDF-TFE-HFP)], vinylidene fluoride-tetrafluoroethylene-perfluoroalkylvinyl ether fluororubber, etc. Is preferred. These vinylidene fluoride (VDF) polymers preferably have a vinylidene fluoride content of 50% by weight or more, especially 70% by weight or more. Among these, polyvinylidene fluoride, a copolymer of vinylidene fluoride (VDF) and hexafluoropropylene (HFP), a copolymer of vinylidene fluoride and ethylene trifluoride chloride [P (VDF-CTFE)] Is particularly preferred. By using a copolymer, the crystallinity is lowered, so that it is easy to impregnate the room-temperature molten salt, and it is easy to hold this.
[0045]
The VDF-CTFE copolymer is commercially available, for example, from Central Glass Co., Ltd. under the trade name "Sefralsoft (G150, G180)", and from Japan Solvay Co., Ltd. under the trade name "Solef 31508". Also, VDF-HFP copolymers are available from Elf Atochem under the trade names “KynarFlex 2750 (VDF: HFP = 85: 15 wt%)”, “KynarFlex 2801 (VDF: HFP = 90: 10 wt%)” and the like. Are sold under the trade names “Solef 11008”, “Solef 11010”, “Solef 21508”, “Solef 21510” and the like.
[0046]
Next, a specific method for producing a gel electrolyte will be described. The production is usually performed in an inert gas atmosphere such as Ar.
[0047]
First, a polymer compound is dissolved in a solvent. The solvent at this time may be appropriately selected from various solvents in which the polymer can be dissolved, and for example, acetone, tetrahydrofuran, methyl acetate and the like are preferably used. The concentration of the polymer in the solvent is preferably 5 to 40% by weight. The dissolution method is preferably to stir while heating to room temperature or 100 ° C. or lower.
[0048]
Then, a room temperature molten salt is added to the polymer solution. The content of the room-temperature molten salt composed of the imidazolium salt and the lithium salt is preferably polymer: room-temperature molten salt = 50: 50 to 20:80 in weight ratio.
[0049]
A mixed solution of a polymer solution and a room temperature molten salt (referred to as a “gel electrolyte solution”) is applied on a substrate. The substrate may be any smooth substrate. For example, polyester film, glass, polytetrafluoroethylene film and the like can be mentioned. Means for applying the gel electrolyte solution to the substrate is not particularly limited, and may be appropriately determined according to the material and shape of the substrate. Generally, a metal mask printing method, an electrostatic coating method, a dip coating method, a spray coating method, a roll coating method, a doctor blade method, a gravure coating method, a screen printing method, and the like are used. Thereafter, if necessary, a rolling treatment is performed by a flat plate press, a calender roll, or the like.
[0050]
Then, the solvent in which the polymer was dissolved is evaporated to obtain a gel electrolyte film. The temperature at which the solvent is evaporated may be room temperature, but may be heated.
[0051]
Note that the room temperature molten salt may be mixed at the time of preparing the gel electrolyte solution as described above, but a film not containing the room temperature molten salt may be prepared in advance and then impregnated with the room temperature molten salt.
[0052]
In order to increase the film strength and swelling property, a filler such as silica or alumina may be added to the gel electrolyte. There is no particular limitation on the material, particle size, shape, and filling amount of the filler to be added. However, since the ionic conductivity of the solid electrolyte decreases with the filling amount, the filling amount is preferably 30 wt% or less.
[0053]
The polymer compound turns into a microporous film. In the present invention, a method described in US Pat. No. 5,418,091 in which a plasticizer is added to a polymer solution, applied to a substrate, and then the solvent is volatilized to form a microporous film. Used.
[0054]
The pore diameter of the microporous polymer membrane is preferably 0.005 to 5 μm, particularly preferably 0.01 to 0.5 μm. Further, a film having a porosity in the range of 20 to 90%, particularly 35 to 70% is practically preferable.
[0055]
The thickness of the polymer solid electrolyte of the present invention is usually 5 to 200 μm.
[0056]
The thus obtained polymer solid electrolyte of the present invention has an electric conductivity of 10 ⁻⁴ to 10 ⁻² S · cm ⁻¹ , which is equivalent to that of a conventional gel electrolyte and close to that of a liquid.
[0057]
The structure of the lithium secondary battery using the gel electrolyte of the present invention is not particularly limited, but is applied to a stacked battery, a cylindrical battery, and the like.
[0058]
Further, for the electrode to be combined with the gel electrolyte, a composition of an electrode active material and a gel electrolyte, and if necessary, a conductive aid is used.
[0059]
The negative electrode uses a negative electrode active material such as a carbon material, a lithium metal, a lithium alloy or an oxide material, and the positive electrode uses an oxide or a carbon material capable of intercalating / deintercalating lithium ions. It is preferable to use a positive electrode active material. By using such an electrode, a lithium secondary battery having excellent characteristics can be obtained.
[0060]
The carbon material used as the electrode active material may be appropriately selected from, for example, mesocarbon microbeads (MCMB), natural or artificial graphite, resin fired carbon material, carbon black, carbon fiber, and the like. These are used as powders. Above all, graphite is preferable, and the average particle diameter is preferably 1 to 30 μm, particularly preferably 5 to 25 μm.
[0061]
As the oxide capable of intercalating / deintercalating lithium ions, a composite oxide containing lithium is preferable, and examples thereof include LiCoO ₂ , LiMn ₂ O ₄ , LiNiO ₂ , and LiV ₂ O ₄ . The average particle size of these oxide powders is preferably about 1 to 40 μm.
[0062]
A conductive assistant is added to the electrode as needed. Examples of the conductive additive include graphite, carbon black, carbon fiber, and metals such as nickel, aluminum, copper, and silver. Graphite and carbon black are particularly preferred.
[0063]
The electrode composition is preferably in the range of 30 to 90: 3 to 10:10 to 70 in terms of weight, in the positive electrode, active material: conductive auxiliary agent: gel electrolyte, and in the negative electrode, the active material: conductive auxiliary agent: weight ratio. : Gel electrolyte = 30 to 90: 0 to 10:10 to 70 is preferable.
[0064]
In the present invention, the negative electrode active material and / or the positive electrode active material, preferably both the active materials, are preferably mixed in the above-mentioned gel electrolyte and adhered to the surface of the current collector.
[0065]
In manufacturing an electrode, first, an active material and, if necessary, a conductive auxiliary are dispersed in a gel electrolyte solution to prepare a coating solution.
[0066]
Then, this electrode coating solution is applied to the current collector. The means for applying is not particularly limited, and may be appropriately determined according to the material and shape of the current collector. Generally, a metal mask printing method, an electrostatic coating method, a dip coating method, a spray coating method, a roll coating method, a doctor blade method, a gravure coating method, a screen printing method, and the like are used. Thereafter, if necessary, a rolling treatment is performed by a flat plate press, a calender roll, or the like.
[0067]
The current collector may be appropriately selected from ordinary current collectors according to the shape of the device used by the battery, the method of disposing the current collector in the case, and the like. Generally, aluminum or the like is used for the positive electrode, and copper, nickel, or the like is used for the negative electrode. Note that a metal foil, a metal mesh, or the like is generally used as the current collector. Although the metal mesh has a smaller contact resistance with the electrode than the metal foil, in the case of the gel electrolyte of the present invention, the metal foil has a sufficiently small contact resistance.
[0068]
Then, the solvent is evaporated to produce an electrode. The coating thickness is preferably about 50 to 400 μm.
[0069]
Thus, by including the same gel electrolyte as the gel electrolyte in the electrode, the adhesion to the gel electrolyte is improved, and the internal resistance is reduced. When lithium metal or lithium alloy is used as the negative electrode active material, the composition of the negative electrode active material and the gel electrolyte may not be used.
[0070]
Further, the polymer solid electrolyte and the electrode of the present invention are also effective for electric double layer capacitors.
[0071]
The current collector used for the polarizable electrode may be a conductive rubber such as a conductive butyl rubber, or may be formed by spraying a metal such as aluminum or nickel, and a metal mesh may be formed on one surface of the electrode layer. It may be attached.
[0072]
The electric double layer capacitor is obtained by combining the above-described polarizable electrode and a gel electrolyte.
[0073]
As the insulating gasket, an insulator such as polypropylene or butyl rubber may be used.
[0074]
Although the structure of the electric double layer capacitor in which the gel electrolyte of the present invention is used is not particularly limited, usually, a pair of polarizable electrodes are arranged via the gel electrolyte, and the polarizable electrode and the peripheral portion of the gel electrolyte are provided. An insulating gasket is disposed. Such an electric double layer capacitor may be any type called a coin type, a paper type, a laminated type, or the like.
[0075]
【Example】
Hereinafter, specific examples of the present invention will be shown, and the present invention will be described in more detail.
[0076]
<Example 1>
All operations were performed in an argon glove box.
[0077]
The following gel electrolytes were used.
[0078]
Polymer matrix PVDF Kynar 2801 (manufactured by Elf Atochem)
(Copolymer of polyvinylidene fluoride and propylene hexafluoride)
Room temperature molten salt (abbreviated as IL)
Mixture of the following 1,3-dimethylimidazolium bis (trifluoromethylsulfonyl) imide (DMIIm) and LiN (CF ₃ SO ₂ ) ₂ DMIIm: LiN (CF ₃ SO ₂ ) ₂ = 2: 1 (molar ratio)
Solvent Acetone (abbreviated as Ac)
[0079]
Embedded image
[0080]
PVDF was used by adding DBP (dibutyl phthalate) to a plasticizer.
[0081]
The above components were weighed so that the weight ratio was PVDF: IL: Ac = 3: 7: 20, mixed and dissolved at room temperature to prepare a gel electrolyte solution.
[0082]
This gel electrolyte solution was applied to a polyethylene terephthalate (PET) film to a width of 50 mm with an applicator having a gap of 0.8 mm. Then, acetone was evaporated in the range of room temperature to 50 ° C. to obtain a gel electrolyte sheet formed into a microporous film.
[0083]
The conductivity of the gel electrolyte at 25 ° C. was measured. The conductivity was measured using an alternating current impedance measurement method. The measurement was performed by cutting out the electrolyte to a diameter of 15 mm and sandwiching it between circular SUS304 electrodes having a diameter of 20 mm. Table 1 shows the results.
[0084]
[Table 1]
[0085]
LiCoO ₂ was used as a positive electrode active material, and acetylene black was used as a conductive additive. These are weighed to the above gel electrolyte solution in a weight ratio of gel electrolyte solution: LiCoO ₂ : acetylene black = 2: 7.5: 1.2, and the cathode active material is added to the gel electrolyte solution at room temperature. The conductive assistant was dispersed and mixed to obtain a positive electrode slurry. The obtained slurry was formed into a coating film by a doctor blade method and dried to obtain a positive electrode. The thickness of this electrode was 0.15 mm.
[0086]
Graphite was used as a negative electrode active material. This was weighed to the gel electrolyte solution in a weight ratio of gel electrolyte solution: graphite = 2: 1, and the negative electrode active material was dispersed and mixed in the gel electrolyte solution at room temperature to obtain a slurry for a negative electrode. . The obtained slurry was formed into a coating film by a doctor blade method and dried to obtain a negative electrode. The thickness of this electrode was 0.15 mm.
[0087]
The gel electrolyte, the positive electrode and the negative electrode thus obtained were cut into predetermined sizes, the respective sheets were laminated, and the periphery was sealed with a polyolefin-based hot melt adhesive or the like to produce a lithium secondary battery.
[0088]
The charge / discharge characteristics of this battery were measured. In the measurement, charging and discharging were performed at a constant current and a constant voltage. As a result of the measurement, the capacity of this battery was 102 mAh.
[0089]
<Example 2>
A mixture of the following 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide (EMIIm) and LiN (CF ₃ SO ₂ ) ₂ (EMIIm: LiN (CF ₃ SO ₂ ) ₂ ) = 2: 1 (molar ratio)), except that a gel electrolyte and a lithium secondary battery using the gel electrolyte were produced in the same manner as in Example 1.
[0090]
Embedded image
[0091]
The conductivity of the obtained gel electrolyte was measured in the same manner as in Example 1. Table 1 shows the results.
[0092]
The charge / discharge characteristics of the obtained battery were measured in the same manner as in Example 1. The capacity of this battery was 97 mAh.
[0093]
<Example 3>
A gel electrolyte and a lithium secondary battery using the gel electrolyte were produced in the same manner as in Example 1, except that a thermoplastic fluororesin was used for the polymer matrix. Specific examples of the thermoplastic fluororesin include trade name Cefralsoft (manufactured by Central Glass Co., Ltd .; a main chain consisting of a copolymer of vinylidene fluoride and chlorofluoroethylene, and a side chain consisting of polyvinylidene fluoride). ) Was used.
[0094]
The conductivity of the obtained gel electrolyte was measured in the same manner as in Example 1. Table 1 shows the results.
[0095]
<Example 4>
A gel electrolyte and a lithium secondary battery using the gel electrolyte were produced in the same manner as in Example 2 except that a thermoplastic fluororesin was used for the polymer matrix. Specific examples of the thermoplastic fluororesin include trade name Cefralsoft (manufactured by Central Glass Co., Ltd .; a main chain consisting of a copolymer of vinylidene fluoride and chlorofluoroethylene, and a side chain consisting of polyvinylidene fluoride). ) Was used.
[0096]
The conductivity of the obtained gel electrolyte was measured in the same manner as in Example 1. Table 1 shows the results.
[0097]
<Reference Example 5>
Under the same conditions as in Example 1, an electrolyte was prepared from PVDF and acetone that had not been formed into a microporous film, and a positive electrode and a negative electrode were stacked. A lithium secondary battery using this gel electrolyte was produced.
[0098]
The conductivity of the obtained gel electrolyte was measured in the same manner as in Example 1. Table 1 shows the results.
[0099]
<Reference Example 6>
Under the same conditions as in Example 2, an electrolyte was prepared from PVDF and acetone that had not been formed into a microporous film, and a positive electrode and a negative electrode were stacked. A lithium secondary battery using this gel electrolyte was produced.
[0100]
The conductivity of the obtained gel electrolyte was measured in the same manner as in Example 1. Table 1 shows the results.
[0101]
The conductivity of the gel electrolyte of the present invention is based on the conductivity (6.56 mS · cm ⁻¹ ) of a normal electrolyte, for example, 1 M LiPF ₆ / EC (ethylene carbonate) + PC (propylene carbonate) (volume ratio 1: 1). Was slightly inferior, but equivalent to the conventional gel electrolyte. In addition, even when batteries were manufactured as in Examples 5 and 6, high conductivity was maintained and the electrolyte functioned.
[0102]
Also, the battery using the gel electrolyte of the present invention was able to obtain the same charge / discharge characteristics as the battery using the conventional gel electrolyte.
[0103]
【The invention's effect】
INDUSTRIAL APPLICABILITY As described above, according to the present invention, without changing the process of the conventional gel electrolyte, a more reliable, safer, high-conductivity polymer solid electrolyte and a lithium secondary battery using the same are used. A double layer capacitor can be provided.

Claims (6)

A polymer solid electrolyte containing an imidazolium salt and a lithium salt represented by the following general formula (I) in a matrix of a fluoropolymer compound,
A polymer solid electrolyte, wherein the fluorine-based polymer compound is formed into a microporous film using a plasticizer.
(In the general formula (I), R ₁ , R ₂ and R ₃ each represent an alkyl group or a hydrogen atom,
A ^- is (RSO _{2) 2} N ^- represents,
R represents a perfluoroalkyl group having 1 to 3 carbon atoms,
When a plurality of Rs are present, they may be the same or different. ) The lithium salt is LiC (RSO ₂ ) ₃ , LiN (RSO ₂ ) ₂ , LiRSO ₃ ,
(R represents a perfluoroalkyl group having 1 to 3 carbon atoms,
When a plurality of Rs are present, they may be the same or different. )
2. The polymer solid electrolyte according to claim 1, which is at least one of LiBF ₄ , LiPF ₆ , LiAsF ₆ and LiClO ₄ . 3. The polymer solid electrolyte according to claim 1, wherein the fluorine-based polymer compound is a homopolymer or a copolymer of vinylidene fluoride. The solid polymer electrolyte according to any one of claims 1 to 3, wherein a mixing ratio of the imidazolium salt and the lithium salt is 10: 1 to 1: 2 in molar ratio. A lithium secondary battery comprising the polymer solid electrolyte according to claim 1. An electric double layer capacitor comprising the polymer solid electrolyte according to claim 1.