JP4968908B2 - ELECTROLYTE COMPOSITION, PROCESS FOR PRODUCING THE SAME AND ELECTROCHEMICAL DEVICE USING ELECTROLYTE COMPOSITION - Google Patents

Description

  The present invention exhibits high ionic conductivity in the substrate direction (that is, the direction perpendicular to the substrate plane) by being oriented horizontally with respect to the substrate plane, and lithium and lithium ion secondary batteries, electric double layer capacitors, photoelectricity The present invention relates to an electrolyte composition having characteristics suitable for various devices such as a chemical battery, an ion sensor, and a photochromic element, a method for producing the same, and an electrochemical element using the electrolyte composition.

  In recent years, due to an increase in demand for energy conversion devices such as lithium and lithium ion secondary batteries, electric double layer capacitors, photoelectrochemical cells, ion sensors, photochromic elements, fuel cells, etc. There is a demand for higher performance.

  The electrolyte is used in the form of an inorganic solid electrolyte using an inorganic material, a polymer solid electrolyte using an organic polymer, and a liquid electrolyte using water or a non-aqueous solvent.

  Among these, polymer solid electrolytes are attracting attention as electrolytes for next-generation lithium secondary batteries. The polymer solid electrolyte has no fear of liquid leakage, is non-volatile, and has a high degree of freedom in shape.

  However, the polymer solid electrolyte has lower ionic conductivity than the liquid electrolyte. For this reason, the improvement of the solid polymer electrolyte is often made for the purpose of improving the ionic conductivity, but the current improvement is insufficient for use as an electrolyte for these devices.

  In order to improve the conductivity by taking advantage of these polymer solid electrolytes, a gel electrolyte obtained by solidifying a liquid electrolyte with a gelling agent or the like has been studied. However, since the gel electrolyte contains a liquid component that volatilizes easily, the gel electrolyte has not yet been improved significantly.

On the other hand, in recent years, various ionic conductors using a liquid crystal material having an intermediate property between a solid and a liquid and utilizing the orientation as a field for ionic conduction have been proposed (see, for example, Patent Document 1).
WO2003 / 062286

  Considering the conditions for practical use, it is desirable that the ionic conductor disposed between the electrodes exhibits high ionic conductivity in the direction between the electrodes at room temperature. However, conventional liquid crystal compounds are not suitable for obtaining such characteristics. For example, the liquid crystal compound disclosed in Patent Document 1 exhibits a smectic liquid crystal phase in which molecules are vertically aligned with respect to the electrode plane. In this state, an effective ion conduction path is formed parallel to the electrode plane. For this reason, the ion conductivity in the direction between the electrodes, that is, in the direction perpendicular to the electrode plane is not sufficiently increased.

  The present invention has been made in view of the above problems, and an object of the present invention is to exhibit high ion conductivity in the substrate direction (that is, the direction perpendicular to the substrate plane) by being horizontally oriented with respect to the substrate plane. It is an object to provide an electrolyte composition, a method for producing the same, and an electrochemical device using the same.

The electrolyte composition of the present invention is an electrolyte composition obtained by polymerizing a mixed composition containing a liquid crystal monomer represented by the following general formula (I) and an electrolyte salt, and is oriented in a horizontal direction with respect to a substrate plane. It is characterized by.
R-α-Xm-β-A-γ-Yn-ω (I)
(R represents an acryl group, a methacryl group, an epoxy group, a vinyl group, or an allyl group represented by Chemical Formula 1. X represents —CH ₂ —, m represents an integer of 1 to 20, and A represents a mesogenic group. Y represents —CH ₂ CH ₂ O— or —CHCH ₃ CH ₂ O—, n represents an integer of 1 to 20, α, β, and γ are oxygen atoms or no oxygen atoms, and ω is a hydrogen atom Or a methyl group)

A of the liquid crystal monomer represented by the general formula (I) is preferably the following structural formulas (I ₁ ) to (I ₁₃ ).

(In the figure, l represents a fluorine atom represented by an integer of 0 to 4.)

(In the figure, l represents the number of fluorine atoms represented by an integer of 0 to 4.)

  It is preferable that a cross-linking agent is further mixed into the mixed composition.

Further, the method for producing an electrolyte composition of the present invention comprises arranging a cell with a pair of alignment film-attached substrates in a state where the alignment axes of the alignment films coincide with each other and the alignment film surfaces face each other with a certain interval. A step of producing, a step of heating the cell above the isotropic phase transition temperature of a mixed composition comprising a liquid crystal monomer represented by the following general formula (I), an electrolyte salt, and a polymerization initiator;
R-α-Xm-β-A-γ-Yn-ω (I)
(R represents an acryl group, a methacryl group, an epoxy group, a vinyl group, or an allyl group represented by Chemical Formula 1. X represents —CH ₂ —, m represents an integer of 1 to 20, and A represents a mesogenic group. Y represents —CH ₂ CH ₂ O— or —CHCH ₃ CH ₂ O—, n represents an integer of 1 to 20, α, β, and γ are oxygen atoms or no oxygen atoms, and ω is a hydrogen atom Or a methyl group)
After injecting the mixed composition into the cell, the step of cooling the cell to a temperature at which a specific liquid crystal phase is developed to obtain a horizontal alignment state with respect to the substrate plane, and heating or light while maintaining the horizontal alignment state And a step of performing a polymerization reaction of a liquid crystal monomer by irradiation to produce an electrolyte composition containing a liquid crystal polymer and an electrolyte salt.

The method for producing an electrolyte composition of the present invention is an isotropy of a mixed composition comprising a liquid crystal monomer represented by the following general formula (I), an electrolyte salt, and a polymerization initiator on one alignment film-attached substrate. Heating to a temperature above the phase transition temperature;
R-α-Xm-β-A-γ-Yn-ω (I)
(R represents an acryl group, a methacryl group, an epoxy group, a vinyl group, or an allyl group represented by Chemical Formula 1. X represents —CH ₂ —, m represents an integer of 1 to 20, and A represents a mesogenic group. Y represents —CH ₂ CH ₂ O— or —CHCH ₃ CH ₂ O—, n represents an integer of 1 to 20, α, β, and γ are oxygen atoms or no oxygen atoms, and ω is a hydrogen atom Or a methyl group)

After the mixed composition is applied on the substrate, the substrate is cooled to a temperature at which a specific liquid crystal phase is developed to be in a horizontal alignment state with respect to the substrate plane, and heated while maintaining the horizontal alignment state. Alternatively, an electrolyte composition containing a liquid crystal polymer and an electrolyte salt is produced by providing a step of polymerizing a liquid crystal monomer by light irradiation.

  It is preferable that a cross-linking agent is further mixed into the mixed composition.

  A lithium ion secondary battery or an electric double layer capacitor can be obtained using the electrolyte composition.

  According to the present invention, when the electrolyte composition is horizontally oriented with respect to the substrate plane, high ion conductivity is exhibited in the substrate direction (that is, the direction perpendicular to the substrate plane). For this reason, it becomes possible to provide an electrolyte composition having a large ion conductivity in the direction perpendicular to the electrode plane that is practically useful (that is, the direction between the electrodes).

(Electrolyte composition)
The electrolyte composition of the present invention is obtained by thermally or photopolymerizing a mixed composition containing a liquid crystal monomer and an electrolyte salt in a horizontal direction with respect to a substrate plane and maintaining this horizontal alignment state. Produced. In addition, it is preferable that a cross-linking agent and a polymerization initiator are also added to the mixed composition. Hereinafter, each element will be described in detail.

(Liquid crystal monomer)
The liquid crystal monomer of the present invention has a structure represented by the following general formula (I).
R-α-Xm-β-A-γ-Yn-ω (I)
(R represents an acryl group, a methacryl group, an epoxy group, a vinyl group, or an allyl group represented by Chemical Formula 1. X represents —CH ₂ —, m represents an integer of 1 to 20, and A represents a mesogenic group. Y represents —CH ₂ CH ₂ O— or —CHCH ₃ CH ₂ O—, n represents an integer of 1 to 20, α, β, and γ are oxygen atoms or no oxygen atoms, and ω is a hydrogen atom Or a methyl group)

In the liquid crystal monomer represented by the general formula (I), examples of the structure of the mesogenic group A include the following.

(In the figure, l represents the number of fluorine atoms represented by an integer from 0 to 4.)

(In the figure, l represents the number of fluorine atoms represented by an integer from 0 to 4.)

(Electrolyte salt)
As the electrolyte salt, alkali metal salts, are particularly suitable lithium salt, _{specifically, LiPF 6, LiBF 4, LiN} (C 2 F 5 SO 2) 2, LiAsF 6, LiSbF 6, LiAlF 4, LiGaF 4 LiInF ₄ , LiClO ₄ , LiN (CF ₃ SO ₂ ) ₂ , LiCF ₃ SO ₃ , LiSiF ₆ , LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ), or the like can be used.

The electrolyte salt may be appropriately selected according to the device. As an electrolyte salt other than the lithium salt, LiI, NaI, KI, CsI, metal iodide such as CaI _2, iodine salt of a quaternary imidazolium compound, an iodine tetraalkylammonium compounds Motoshio, LiBr, NaBr, KBr, CsBr, A metal bromide such as CaBr ₂ can be exemplified.

  Another preferred example of the electrolyte salt is protonic acid. The proton acid may be an inorganic acid or an organic acid. Inorganic acids include nitric acid, sulfuric acid, sulfurous acid, bisulfite, phosphoric acid, phosphorous acid, hypophosphoric acid, metaphosphoric acid, hypophosphorous acid, amidophosphoric acid, carbonic acid, bicarbonate, hydrochloric acid, hydrobromic acid, hydroiodic acid, orthoboron. Examples thereof include acid, metaboric acid, aluminate, amidosulfuric acid, hydrazinosulfuric acid and sulfamic acid. Organic acids include isovaleric acid, isobutyric acid, octanoic acid, cyclohexanecarboxylic acid, lactic acid, acetic acid, butyric acid, crotonic acid, azelaic acid, citric acid, succinic acid, oxalic acid, tartaric acid, fumaric acid, malonic acid, malic acid , Lauric acid, myristic acid, palmitic acid, stearic acid, anisic acid, benzoic acid, p-aminobenzoic acid, naphthoic acid, terephthalic acid, pyromellitic acid, asparagine, aspartic acid, 4-aminobutyric acid, alanine, arginine, isoleucine Glycine, glutamic acid, cysteine, serine, valine, histidine, methionine, leucine, benzoic acid, benzoic acid-2-phosphate, adenosine-2'-phosphate, phenol-3-phosphate, galactose-1-phosphate, Benzenephosphonic acid, 2-aminoethylphosphonic acid, 2-bromo-p-tolylphos Acid, 2-methoxyphenylphosphonic acid, t-butylphosphinic acid, o-cresol, m-cresol, p-cresol, 4-amino-m-cresol, 2,4-dinitrophenol -Ol, o-bromophenol, p-phenolsulfonic acid, p-acetylphenol, ascorbic acid, reductin, 3-hydroxyphenylboric acid, 3-aminophenylboric acid, β-phenylethylboronic acid, hydrazine Examples thereof include -N, N-diacetic acid and hydrazine-N, N'-diacetic acid. Protonic acid is not limited to the above, and sulfonylimide acid and derivatives thereof are also preferable.

(Cross-linking agent)
In the present invention, in order to give sufficient mechanical strength when a mixed composition comprising a liquid crystal monomer and an electrolyte salt is polymerized to form an electrolyte film, It is preferable to use a polyfunctional (meth) acrylate having two or more (meth) acryloyl groups. Such polyfunctional (meth) acrylate can be used in the range of usually 0.1 to 20 mol%, preferably 0.5 to 10 mol%, based on 100 mol% of the liquid crystal monomer. In addition, it is better to use a larger amount in the case of bifunctionality and a smaller amount in the case of a polyfunctionality of 3 or more functionalities. If it is less than 0.1 mol%, the degree of cross-linking will be low, and the mechanical strength of the electrolyte film will be weak. On the other hand, if it exceeds 20 mol%, phase separation is likely to occur with the liquid crystal compound. Alternatively, the liquid crystal phase is not likely to be expressed.

  Such polyfunctional (meth) acrylates include ethylene glycol di (meth) acrylate, propanediol di (meth) acrylate, butanediol di (meth) acrylate, nonanediol di (meth) acrylate, and hexanediol di (meth). Di (meth) acrylates derived from alkanediols such as acrylate Tetraethylene glycol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) ethylene glycol such as (poly) propylene glycol di (meth) acrylate And (poly) propylene glycol-derived di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, trimethylolpropane tri (meth) acrylate Di-, tri- or tetra (meth) acrylates derived from polyhydric alcohols such as pentaerythritol tri (meth) acrylate and dipentaerythritol hexa (meth) acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, urethane (meta ) Acrylate, etc.

(Polymerization reaction)
The polymerization reaction is performed by a photopolymerization method such as ultraviolet rays or a thermal polymerization method. From the viewpoint of processability to an electrolyte film, it is preferable to use a photopolymerization method. This photopolymerization method is preferably performed in an oxygen-free atmosphere substituted with an inert gas such as nitrogen gas, or in a state where it is shielded from air by coating with an ultraviolet transparent substrate.

In the photopolymerization method, ultraviolet rays are electromagnetic radiation having a wavelength range of about 180 to 460 nm, but may be electromagnetic radiation having a longer wavelength or shorter wavelength. Irradiation devices such as a mercury arc, a carbon arc, a low pressure mercury lamp, a medium / high pressure mercury lamp, a metal halide lamp are used as the ultraviolet ray source. The intensity of the ultraviolet rays can be appropriately set by adjusting the distance to the irradiated object and the voltage. In consideration of irradiation time (productivity), it is usually desirable to use light of 0.1 to 100 mW / cm ² .

(Photopolymerization initiator)
As photopolymerization initiators, 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone, α-hydroxy-α, α'-dimethylacetophenone, methoxyacetophenone, 2,2-dimethoxy-2-phenyl Acetophenone compounds such as acetophenone, 2,2-diethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) -phenyl] -2-morpholinobroban-1, benzoin ethyl ether, benzoin Benzoin ether compounds such as isopropyl ether and anisoin methyl ether, α-ketol compounds such as 2-methyl-2-hydroxypropiophenone, ketal compounds such as benzyldimethyl ketal, 2-naphthalenesulfonyl chloride Aromatic sulfonyl chloride compounds such as 1-phenone-1,1-propanedione-2- (o-ethoxycarbonyl) oxime, benzophenone, benzoylbenzoic acid, 3,3′-dimethyl And benzophenone-based compounds such as -4-methoxybenzophenone.

(Low molecular weight component)
In the present invention, a low molecular weight component such as a plasticizer can be added to the mixed composition comprising the liquid crystal monomer and the electrolyte salt within a range not disturbing the alignment of the liquid crystal. Examples of the low molecular weight component include (poly) ethylene oxide, (poly) propylene oxide, (poly) ethyleneimine, (poly) siloxane, and the like having a polystyrene-equivalent weight average molecular weight of 10,000 or less.

(Electrolyte)
Moreover, in this invention, electrolyte solution can be added to the mixed composition which consists of a liquid crystal monomer and electrolyte salt as needed. Here, the electrolytic solution is a solution obtained by dissolving an electrolyte salt in a solvent. As the electrolyte salt, the above-described electrolyte salt can be used. Among these, electrolyte salts containing alkali metal ions are particularly preferably used.

  Any solvent can be used as the solvent for the electrolytic solution as long as it dissolves the above-described electrolyte salt. Examples of non-aqueous solvents include ethylene carbonate, propylene carbonate, butylene carbonate, and γ-butyrolactone. Cyclic esters such as tetrahydrofuran, ethers such as dimethoxyethane, and chain esters such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. These solvents are used alone or as a mixture of two or more kinds.

(Method for producing electrolyte composition)
In order to prepare the above-described electrolyte composition, first, the above liquid crystal monomer, electrolyte salt, cross-linking agent and polymerization initiator are dissolved in a solvent to obtain a uniform state, and then the solvent is removed by vacuum drying or the like. Thus, a liquid crystal monomer-electrolyte salt mixed composition is prepared.

  The solvent used for dissolving the liquid crystal monomer, electrolyte salt, cross-linking agent and polymerization initiator is not particularly limited as long as each component can be dissolved, but tetrahydrofuran, dichloromethane, trichloromethane, etc. are preferably used. It is done.

  Next, the liquid crystal monomer-electrolyte salt mixture composition is aligned in the horizontal direction with respect to the substrate plane.

(Horizontal orientation method)
There are roughly two methods for horizontally aligning the liquid crystal monomer-electrolyte salt mixture composition. As a first method, first, a cell in which a pair of alignment film-attached substrates are aligned with the alignment axes of the alignment films and the alignment film surfaces are opposed to each other with a certain interval is produced.

  In FIG. 1, sectional drawing of the cell used for the manufacturing method of the electrolyte composition of this invention is shown. In this cell, an upper substrate 1 with an alignment film 2 and a lower substrate 5 with an alignment film 3 are opposed to each other with a spacer 4 interposed therebetween.

  Next, this cell is heated above the isotropic phase transition temperature of the liquid crystal monomer-electrolyte salt mixture composition, and then the mixture composition is injected into the cell. Thereafter, the cell is cooled to a temperature at which a desired liquid crystal phase is developed. Further, the liquid crystal monomer and the cross-linking agent are polymerized by the above-described polymerization method while maintaining the alignment state of the liquid crystal phase. Thus, an electrolyte composition comprising a liquid crystal polymer partially crosslinked with a cross-linking agent and an electrolyte salt can be produced.

  Further, as a second method, one substrate with an alignment film is heated to a temperature higher than the isotropic phase transition temperature of the liquid crystal monomer-electrolyte salt mixture composition, and this composition is applied onto one substrate with an alignment film. To do. Thereafter, the substrate is cooled to a temperature at which a specific liquid crystal phase is developed. Further, the liquid crystal monomer and the cross-linking agent are polymerized by the above-described polymerization method while maintaining the horizontal alignment state. Thus, an electrolyte composition comprising a liquid crystal polymer partially crosslinked with a cross-linking agent and an electrolyte salt can be produced.

(Alignment film)
The alignment film used for the substrate with the alignment film is not particularly limited as long as it has the ability to align liquid crystal. For example, a film obtained by rubbing a polymer such as polyvinyl alcohol or polyimide and their modified products. A film in which SiO is obliquely vapor-deposited can be used. From the viewpoint of the water resistance of the alignment film and the ease of handling, a rubbing film made of a polyimide or a modified product thereof is preferably used.

  In the case of using a substrate with an alignment film subjected to rubbing treatment, as shown in FIG. 2, the rubbing direction 6 of the alignment film 2 and the rubbing of the alignment film 3 are performed as shown in FIG. It is preferable to face the direction 7 so as to be in the opposite direction (anti-parallel).

  The upper substrate 1 and the lower substrate 5 on which the alignment film is provided are not particularly limited as long as the surface is smooth, but a metallic film polyether such as a glass plate quartz plate, a calcium fluoride plate, an aluminum film, or a stainless film. A plastic film such as a sulfone film, a polyimide film, or a polyester film is preferably used.

(Liquid crystal phase)
As the liquid crystal phase, it is preferable to use a smectic liquid crystal. The smectic liquid crystal is a liquid crystal phase having a one-dimensional positional order and a layer structure in addition to the alignment order. In the present invention, as shown in FIG. 3, an ion conduction path 9 is formed in a direction perpendicular to the substrate plane by horizontally aligning the electrolyte composition 8 made of smectic liquid crystal with respect to the substrate plane. Improve conductivity. Specifically, the smectic liquid crystal is preferably the smectic phase described in the Liquid Crystal Handbook Editorial Committee, “Liquid Crystal Handbook”, Maruzen Co., Ltd., October 30, 2000, p.12-16, and in particular, the smectic A phase or A smectic C phase or a smectic B phase (hexatic B phase, crystal B phase) is preferred.

(Thickness of electrolyte composition)
The thickness of the electrolyte composition produced by the above method is preferably 5 to 60 μm, and particularly preferably 15 to 30 μm. When the thickness of the electrolyte composition is less than 5 μm, there is a high possibility of causing a short circuit between the positive electrode and the negative electrode, and when the thickness of the electrolyte composition is more than 60 μm, the molecular orientation forming the ion conduction path tends to be disturbed. is there.

(Lithium ion secondary battery)
The electrolyte composition of the present invention can be used as an electrolyte of a lithium ion secondary battery. Although the structure of the lithium ion secondary battery using the electrolyte composition of the present invention is not particularly limited, it is usually composed of a negative electrode 10, a positive electrode 20, and an electrolyte 30, as shown in FIG. And is applied to cylindrical batteries and the like.

  The electrode combined with the electrolyte composition may be appropriately selected from those known as electrodes for lithium ion secondary batteries, and a mixture of an electrode active material and an electrolyte composition can also be used.

  The negative electrode 10 includes a negative electrode active material 11 and a current collector 12, and examples of the negative electrode active material 11 include carbon, lithium metal, a lithium alloy, and an oxide material.

  The carbon used as the active material may be appropriately selected from, for example, natural or artificial graphite, resin-fired carbon material, carbon fiber, and the like. These are used in powder form. Among these, graphite is preferable, and the average particle diameter is preferably 1 to 30 μm, particularly preferably 5 to 25 μm. When the average particle size is less than 1 μm, the charge / discharge cycle life is shortened and the capacity variation (individual difference) tends to increase. When the average particle diameter is larger than 30 μm, the variation in capacity becomes remarkably large and the average capacity becomes small. The reason why the variation in capacity occurs when the average particle size is large is thought to be because the contact between graphite and the current collector or the contact between graphites varies.

  The positive electrode 20 includes a positive electrode active material 21 and a current collector 22, and examples of the positive electrode active material 21 include oxides or carbon that can intercalate and deintercalate lithium ions. By using such an electrode, a lithium ion secondary battery with good characteristics can be obtained.

The oxide capable of intercalating and deintercalating lithium ions is preferably a composite oxide containing lithium, 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.

  If necessary, a conductive aid is added to the negative electrode 10 and the positive electrode 20. Preferred examples of the conductive aid include metals such as graphite, carbon black, carbon fiber, nickel, aluminum, copper, and silver, and graphite and carbon black are particularly preferable.

  In manufacturing the electrode, first, an active material and, if necessary, a conductive additive are dispersed in a binder solution to prepare a coating solution.

  Then, this electrode coating solution is applied to the current collectors 12 and 22. The means for applying is not particularly limited, and may be appropriately determined according to the material and shape of the current collectors 12 and 22. In general, 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. Then, if necessary, a rolling process is performed using a flat plate press, a calendar roll, or the like.

  The current collectors 12 and 22 may be appropriately selected from ordinary current collectors according to the shape of the device used by the battery, the method of arranging the current collector in the case, and the like. In general, the current collector 12 is made of copper, nickel or the like, and the current collector 22 is made of aluminum or the like. The current collectors 12 and 22 are usually made of metal foil, metal mesh, or the like. The metal mesh has a smaller contact resistance with the electrode than the metal foil, but a sufficiently small contact resistance can be obtained even with the metal foil.

  And the solvent is evaporated and the negative electrode 10 and the positive electrode 20 are produced. The coating thickness is preferably about 50 to 1,000 μm.

  The negative electrode 10 and the positive electrode 20 obtained in this way are laminated in the order of the positive electrode 20, the electrolyte 30, and the negative electrode 30, and are pressed to form a lithium ion secondary battery.

(Electric double layer capacitor)
The electrolyte composition of the present invention can also be used for electric double layer capacitors.
FIG. 5 shows a schematic diagram of an electric double layer capacitor. The electric double layer capacitor generally has a structure in which a pair of polarizable electrodes 41 and an electrolyte 42 are disposed between them in a case. Further, the collector electrode 43 is on the opposite side of the polarizable electrode 41, and these are enclosed in a hermetically sealed case.

  An electrolyte may be present between the polarizable electrodes 41 alone, but a combination of an electrolyte and a nonwoven fabric or porous membrane separator may be used. Examples of the material for the separator include polyethylene, polypropylene, polyamide, polyester, polytetrafluoroethylene, and the like. The thickness between the polarizable electrodes is usually set to about 10 μm to 500 μm.

  Activated carbon is preferably used as the material of the polarizable electrode 41. As the raw material of such activated carbon, plant materials such as coconut husk and bamboo, synthetic resin materials such as phenol resin and polyvinyl alcohol, synthetic mesophase pitch, coal, natural Examples thereof include pitch materials such as pitch and isotropic pitch. Activated carbon produced by gas activation, chemical activation of potassium hydroxide, zinc chloride, or the like can be used as the polarizable material. The shape of the activated carbon is arbitrary, such as granular, cloth-like, crushed fiber, and fibrous.

  When activated carbon is in the form of a cloth, it can be used as it is. In the case of granular or crushed fibers, a binder typified by polytetrafluoroethylene or polydifluoroethylene, a conductive material such as carbon black, and What is necessary is just to apply | coat the mixture with an organic solvent on a current collection member, and to dry.

  The thickness of the polarizable electrode 41 is usually about 20 μm to 1 mm.

  Examples of the current collecting member that becomes the current collecting electrode 43 include aluminum and nickel. In order to reduce the resistance of the current collecting member, aluminum in which the metal foil as the current collecting member and the polarizable electrode 41 are bonded with a synthetic resin containing a conductive material such as carbon black is sprayed on the polarizable electrode 41. May be.

  Hereinafter, the present invention will be described more specifically with reference to examples.

According to the synthesis method described in Example 3 of Patent Document 1, the following liquid crystal monomer M1 was obtained.
<Liquid crystal monomer M1>

  Next, a liquid crystal alignment coating agent RN-1199 manufactured by Nissan Chemical Industries, Ltd. was applied to a glass plate by spin coating, dried on a hot plate at 80 ° C. for 5 minutes, and then heated at 250 ° C. with a hot air circulating dryer. Time firing was performed. Further, the obtained glass substrate with an alignment film is rubbed with a rayon cloth, and as shown in FIG. 2, the rubbing direction 5 of the alignment film 2 of the glass substrate (upper substrate) 1 and the alignment of the glass substrate (lower substrate) 5 The glass substrates 1 and 5 with the alignment films 2 and 3 were produced so as to face each other so that the rubbing direction 6 of the film 3 was opposite (anti-parallel). In addition, as the spacer 4, a polystyrene standard particle having a diameter of 25 μm or a polyphenylene sulfide film with an adhesive having a thickness of 25 μm was used.

Next, in tetrahydrofuran solvent, the liquid crystal monomer M1 100mol%, LiCF ₃ SO ₃ to 20.5mol%, 5mol% 1,6-hexanediol diacrylate as a crosslinking agent as an electrolyte salt, photopolymerization After dissolving 1 mol% of 2,2-dimethoxy-2-phenylacetophenone as an initiator so as to be uniform, it is desolvated overnight at room temperature in a vacuum dryer, whereby a liquid crystal monomer-electrolyte mixture composition Was made.

Next, the cell was heated to 95 ° C. on a hot plate. The liquid crystal monomer-electrolyte salt mixed composition was poured into the heated cell to make a transparent solution. Thereafter, the hot plate temperature was naturally allowed to cool to 60 ° C. at which the smectic A phase was developed, so that the temperature of the cell into which the liquid crystal monomer-electrolyte salt mixed composition was injected was set to 60 ° C. While maintaining the state of the cell, using a spot UV device, an ultraviolet ray was irradiated at 35 mW / cm ² for 5 minutes to prepare an electrolyte composition composed of a liquid crystal polymer partially crosslinked with a cross-linking agent and an electrolyte salt. . When the obtained liquid crystal polymer-electrolyte salt mixed composition was observed at room temperature under a crossed Nicol with a polarizing microscope, the brightness of the observed image was changed by rotating the stage by 45 °. From this, it was confirmed that the liquid crystal of the obtained liquid crystal polymer-electrolyte salt mixed composition was horizontally aligned.

Next, the liquid crystal polymer-electrolyte salt mixed composition was peeled from the glass substrate to obtain a film-like electrolyte composition. The ionic conductivity of the obtained electrolyte composition was 3 × 10 ⁻⁶ S / cm.
The ionic conductivity was measured by the method described below. The obtained film-like electrolyte composition was cut into a predetermined area and sandwiched between a pair of nickel electrodes. Using an impedance measuring device (Yokogawa Hewlett-Packard 4284A), an AC voltage of 0.3 V was applied at room temperature for measurement. The real component impedance at the intersection of the arc on the high frequency side and the straight line on the low frequency side was determined by the complex impedance method, and the conductivity σ (S / cm) was calculated based on the following equation.
σv = d / (R × A)
d: electrolyte thickness (cm), R: real component impedance (Ω), A: electrolyte area (cm 2)

Liquid crystal polymer-electrolyte salt mixed composition as in Example 1 except that 1,6-hexanediol diacrylate was not added when preparing the liquid crystal monomer-electrolyte mixed composition described in Example 1. A product was made. When the obtained liquid crystal polymer-electrolyte salt mixed composition was observed at room temperature under a crossed Nicol with a polarizing microscope, the brightness of the observed image was changed by rotating the stage by 45 °. From this, it was confirmed that the liquid crystal of the obtained liquid crystal polymer-electrolyte salt mixed composition was horizontally aligned. Moreover, the ionic conductivity of the film-like electrolyte composition obtained by peeling the liquid crystal polymer-electrolyte salt mixture composition from the glass substrate was 8 × 10 ⁻⁶ S / cm.

When preparing the liquid crystal monomer-electrolyte mixed composition described in Example 1, a liquid crystal polymer-electrolyte salt mixed composition was prepared in the same manner as in Example 1 except that tetraethylene glycol diacrylate was added. When the obtained liquid crystal polymer-electrolyte salt mixed composition was observed at room temperature under a crossed Nicol with a polarizing microscope, the brightness of the observed image was changed by rotating the stage by 45 °. From this, it was confirmed that the liquid crystal of the obtained liquid crystal polymer-electrolyte salt mixed composition was horizontally aligned. Moreover, the ionic conductivity of the film-like electrolyte composition obtained by peeling the liquid crystal polymer-electrolyte salt mixed composition from the glass substrate was 1.0 × 10 ⁻⁵ S / cm.

A liquid crystal polymer-electrolyte salt mixture composition was prepared in the same manner as in Example 1 except that 1,6-hexanediol dimethacrylate was added when the liquid crystal monomer-electrolyte mixture composition described in Example 1 was prepared. Produced. When the obtained liquid crystal polymer-electrolyte salt mixed composition was observed at room temperature under a crossed Nicol with a polarizing microscope, the brightness of the observed image was changed by rotating the stage by 45 °. From this, it was confirmed that the liquid crystal of the obtained liquid crystal polymer-electrolyte salt mixed composition was horizontally aligned. Moreover, the ionic conductivity of the film-like electrolyte composition obtained by peeling the liquid crystal polymer-electrolyte salt mixed composition from the glass plate was 1.5 × 10 ⁻⁵ S / cm.

A liquid crystal polymer-electrolyte salt mixture composition was prepared in the same manner as in Example 1 except that 1,9-nonanediol dimethacrylate was added when preparing the liquid crystal monomer-electrolyte mixture composition described in Example 1. Produced. When the obtained liquid crystal polymer-electrolyte salt mixed composition was observed at room temperature under a crossed Nicol with a polarizing microscope, the brightness of the observed image was changed by rotating the stage by 45 °. From this, it was confirmed that the liquid crystal of the obtained liquid crystal polymer-electrolyte salt mixed composition was horizontally aligned. Moreover, the ionic conductivity of the film-like electrolyte composition obtained by peeling the liquid crystal polymer-electrolyte salt mixed composition from the glass substrate was 1.2 × 10 ⁻⁵ S / cm.

Comparative Example 1

  A liquid crystal polymer-electrolyte salt mixture was prepared in the same manner as in Example 1 except that no alignment film was formed on the glass substrate. When the obtained liquid crystal polymer-electrolyte salt mixture composition was observed at room temperature under crossed Nicols with a polarizing microscope, the brightness of the observed image did not change even when the stage was rotated 45 °. From this, it was confirmed that the liquid crystal of the obtained liquid crystal polymer-electrolyte salt mixture composition was not horizontally aligned.

Furthermore, the ionic conductivity of the film-like electrolyte composition obtained by peeling this liquid crystal polymer-electrolyte salt mixed composition from the glass substrate is 4 × 10 ⁻⁷ S / cm, and the ionic conductivity is that of Example. It was remarkably small compared with.

  It should be noted that the electrolyte composition of the present invention is not limited to the above-described examples, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

Industrial applicability

  According to the present invention, it is possible to provide an electrolyte composition having a high ion conductivity in a direction perpendicular to a practically useful electrode plane, lithium and a lithium ion secondary battery, an electric double layer capacitor, a photoelectrochemical battery, an ion It can be suitably used for various devices such as sensors and photochromic elements.

It is sectional drawing which shows an example of the cell used for the manufacturing method of the electrolyte composition of this invention. It is a perspective view which shows an example of the cell used for the manufacturing method of the electrolyte composition of this invention. In this invention, it is the schematic diagram which formed the ion conduction path in the orthogonal | vertical direction with respect to the board | substrate plane direction. It is typical sectional drawing which shows an example of the lithium ion secondary battery of this invention. It is typical sectional drawing which shows an example of the electrical double layer capacitor of this invention.

Explanation of symbols

1 Upper substrate (glass substrate)
2 Alignment film 3 Alignment film 4 Spacer 5 Lower substrate (glass substrate)
6 Rubbing direction of alignment film 2 7 Rubbing direction of alignment film 3 10 Negative electrode 11 Negative electrode active material 12 Current collector 20 Positive electrode 21 Positive electrode active material 22 Current collector 30 Electrolyte 41 Polarized electrode 42 Electrolyte 43 Current collecting electrode

Claims (10)

A film-like electrolyte composition formed by polymerizing a mixed composition containing a liquid crystal monomer represented by the following general formula (I) and an electrolyte salt, with respect to the film surface of the electrolyte composition An electrolyte composition, wherein the liquid crystal polymer is aligned in a horizontal direction.
R-α-Xm-β-A-γ-Yn-ω (I)
(R represents an acryl group, a methacryl group, an epoxy group, a vinyl group, or an allyl group represented by Chemical Formula 1. X represents —CH ₂ —, m represents an integer of 1 to 20, and A represents a mesogenic group. Y represents —CH ₂ CH ₂ O— or —CHCH ₃ CH ₂ O—, n represents an integer of 1 to 20, α, β, and γ are oxygen atoms or no oxygen atoms, and ω is a hydrogen atom Or a methyl group)
2. The electrolyte composition according to claim 1, wherein A of the liquid crystal monomer represented by the general formula (I) is represented by the following structural formulas (I ₁ ) to (I ₁₃ ).


(In the figure, l represents the number of fluorine atoms represented by an integer from 0 to 4.)



(In the figure, l represents the number of fluorine atoms represented by an integer of 0 to 4.)   The electrolyte composition according to claim 1, wherein a cross-linking agent is further mixed with the mixed composition. Arranging a pair of alignment film-attached substrates in a state in which the alignment axes of the alignment films coincide with each other and the alignment film surfaces face each other with a certain interval;
Heating the cell above the isotropic phase transition temperature of a mixed composition comprising a liquid crystal monomer represented by the following general formula (I), an electrolyte salt, and a polymerization initiator;
R-α-Xm-β-A-γ-Yn-ω (I)
(R represents an acryl group, a methacryl group, an epoxy group, a vinyl group, or an allyl group represented by Chemical Formula 1. X represents —CH ₂ —, m represents an integer of 1 to 20, and A represents a mesogenic group. Y represents —CH ₂ CH ₂ O— or —CHCH ₃ CH ₂ O—, n represents an integer of 1 to 20, α, β, and γ are oxygen atoms or no oxygen atoms, and ω is a hydrogen atom Or a methyl group)
After injecting the mixed composition into the cell, the step of cooling the cell to a temperature at which a specific liquid crystal phase is developed to be in a horizontal alignment state with respect to the substrate plane;
A step of performing a polymerization reaction of a liquid crystal monomer by heating or light irradiation while maintaining the horizontal alignment state ;
A step of peeling the film-like electrolyte composition formed by polymerization from the substrate with the alignment film , thereby producing an electrolyte composition containing a liquid crystal polymer and an electrolyte salt. A method for producing an electrolyte composition. Heating one alignment film-attached substrate to an isotropic phase transition temperature or higher of a mixed composition containing a liquid crystal monomer represented by the following general formula (I), an electrolyte salt, and a polymerization initiator;
R-α-Xm-β-A-γ-Yn-ω (I)
(R represents an acryl group, a methacryl group, an epoxy group, a vinyl group, or an allyl group represented by Chemical Formula 1. X represents —CH ₂ —, m represents an integer of 1 to 20, and A represents a mesogenic group. Y represents —CH ₂ CH ₂ O— or —CHCH ₃ CH ₂ O—, n represents an integer of 1 to 20, α, β, and γ are oxygen atoms or no oxygen atoms, and ω is a hydrogen atom Or a methyl group)
After applying the mixed composition on the substrate, cooling the substrate to a temperature at which a specific liquid crystal phase is developed to be in a horizontal alignment state with respect to the substrate plane;
A step of performing a polymerization reaction of a liquid crystal monomer by heating or light irradiation while maintaining the horizontal alignment state ;
A step of peeling the film-like electrolyte composition formed by polymerization from the substrate with the alignment film , thereby producing an electrolyte composition containing a liquid crystal polymer and an electrolyte salt. A method for producing an electrolyte composition.   6. The method for producing an electrolyte composition according to claim 4, further comprising a cross-linking agent mixed with the mixed composition.   The lithium ion secondary battery using the electrolyte composition of any one of Claims 1-3.   The electric double layer capacitor using the electrolyte composition of any one of Claims 1-3. An electrolyte composition according to any one of claims 1 to 3, and two electrodes arranged so as to be in contact with both surfaces of the film of the electrolyte composition and sandwiching the electrolyte composition therebetween, The lithium ion secondary battery according to claim 7 . An electrolyte composition according to any one of claims 1 to 3, and two electrodes arranged so as to be in contact with both surfaces of the film of the electrolyte composition and sandwiching the electrolyte composition therebetween, The electric double layer capacitor according to claim 8 .