JPH10302838A - Ion conductive polymer solid electrolyte and electrochemical element containing this solid electrolyte - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid electrolyte with high ionic conductivity, high uniformity, high ionic conductivity especially at low temperature, using a polymer having solid strength sufficient to use as the solid electrolyte of an electrochemical element as a matrix, and provide an electrochemical element, especially a nonaqueous secondary battery using this solid electrolyte. SOLUTION: In a polymer solid electrolyte using a polymer as a matrix, a polymer solid electrolyte contains at least a double salt of Lewis acid represented by formula, LiXFn (wherein X is B, P, As, or Sb, when X is B, n is 4, and when X is P, As, or Sb, n is 6), a cyclic carbonate and an acyclic carbonate, and the volume ratio of the cyclic carbonate and the acyclic carbonate is less than 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a novel solid electrolyte and an electrochemical device using the solid electrolyte, particularly a non-aqueous secondary battery.

[0002]

2. Description of the Related Art In an electrochemical device containing an electrolyte, solidification (solidification) of the electrolyte is strongly desired. Conventionally, a battery as an electrochemical element uses an electrolytic solution, which causes not only leakage of the electrolytic solution and drying in the battery due to volatilization of the solvent, but also, in the battery container, a diaphragm is formed due to the direction of the electrolytic solution. It becomes partially dry, which causes an increase in internal impedance or an internal short circuit. Also, no solid electrolyte for display of an electrochromic device has sufficiently obtained an operation speed. As a method for solving these drawbacks, it has been proposed to use a solid polymer electrolyte. Specific examples thereof include a solid solution of a matrix polymer containing an oxyethylene chain or an oxypropylene chain and an inorganic salt, which is a completely solid and has excellent workability, but has an ionic conductivity of 1 / at room temperature. 105S /
cm, which is about three orders of magnitude lower than ordinary non-aqueous electrolytes.

Further, in order to improve the ionic conductivity of a solid polymer electrolyte, a method of dissolving an organic electrolyte solution in a polymer to obtain a semi-solid solution (Japanese Patent Application Laid-Open No. 54-104541) or adding an electrolyte. A polymerizable reaction of the liquid monomer to form a crosslinked polymer containing an electrolyte (Japanese Patent Laid-Open No. 63-945).
No. 01 publication) has been proposed. However, the solid electrolyte obtained by the former method involves a problem that its strength is not sufficient, and the solid electrolyte obtained by the latter method is still unsatisfactory in terms of ionic conductivity although sufficient solid strength is obtained. Includes the problem.

As a solid electrolyte having excellent ionic conductivity and uniformity and having sufficient solid strength for use as a solid electrolyte for an electrochemical device, gel has recently been receiving attention. The reason is that the ion conductivity is high, the uniformity is excellent, the solid strength sufficient for use as a solid electrolyte for electrochemical devices can be obtained, and the processability is rich, so the reliability of electrochemical devices can be improved. This is useful, and in particular, a battery or the like having excellent repetition characteristics can be obtained.
In recent years, a solid electrolyte having a composition containing an electrolytic solution has been developed, but the solid strength is sufficient as an electrochemical element, but the ionic conductivity is not yet sufficient, or the solid strength is high even though the ionic conductivity is high. However, at present, none satisfying these various requirements has been obtained, for example, the ionic conductivity is not sufficient and the ionic conductivity is extremely lowered at low temperatures.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems encountered in the conventional solid electrolyte having a polymer as a matrix. Provided is a solid electrolyte which has a solid strength sufficient for use as an electrolyte and has a matrix of a polymer having particularly good ionic conductivity at a low temperature, and an electrochemical element using the solid electrolyte, particularly a non-aqueous secondary battery. The purpose is to:

[0006]

A feature of the present invention is that in a solid polymer electrolyte having a polymer as a matrix (hereinafter also referred to as a solid polymer electrolyte), the solid polymer electrolyte has at least the following formula (I)

Embedded image wherein X is B, P, As, Sb, and when X is B, n is 4; and when X is B, P, As, Sb, it is 6. An ion conductive polymer comprising a Lewis acid double salt (A) and a cyclic carbonate and an acyclic carbonate (B), wherein the volume ratio of the cyclic carbonate / acyclic carbonate is less than 1. The problem of the prior art is solved by providing a solid electrolyte.

That is, in the present invention, a mixed solvent in which at least a volume ratio of a cyclic carbonate and an acyclic carbonate (B) is less than 1 to a solid polymer electrolyte and a Lewis acid complex represented by the formula (I) By including the salt, without deteriorating the elastic modulus of the polymer solid electrolyte,
Electrochemistry that can improve ionic conductivity, especially at low temperatures, has very high reliability and ionic conductivity, and has sufficient solid strength for use as a solid electrolyte The inventors have found that a polymer solid electrolyte for a device can be obtained, and have reached the present invention.

The solid polymer electrolyte of the present invention has the following formula (II):

Embedded image LiX (SO ₂ R ₃ ) n (II) wherein X is an N, C, B, O or CR ₄ group (R ₄ is an alkyl group), and R ₃ is CF ₃ or C ₂ it is F _5, n is an integer of 1-3. ], The above effect can be further improved.

The solid electrolyte of the present invention may be prepared by dissolving a polymerizable compound in the non-aqueous electrolytic solution to cause a polymerization reaction, or by polymerizing the polymerizable compound to form a polymer on the non-aqueous electrolytic solution. It can also be formed by impregnating with a liquid. In this case, the polymerizable compound is heat-polymerizable,
An active ray such as light, ultraviolet ray, electron beam, γ-ray, X-ray or the like, which is polymerizable, is used. The formation of the polymer solid electrolyte by the polymerization reaction is preferably performed in an inert gas atmosphere. By performing the reaction in an inert gas atmosphere, a polymer solid electrolyte which is superior in terms of ionic conductivity, strength, and the like can be obtained as compared with the case of manufacturing in the atmosphere.

Hereinafter, the method for producing the solid polymer electrolyte of the present invention, its features, and its configuration will be described in detail. [1. Polymer Solid Electrolyte] (1) Non-aqueous Electrolyte (i) Solvent As the solvent constituting the non-aqueous electrolyte, the mixed solvent containing a cyclic carbonate and a non-cyclic carbonate as described above is used to form an ion. A solid electrolyte with improved conductivity and elastic modulus can be obtained. Non-cyclic carbonates include, but are not limited to, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, dipropyl carbonate, diisopropyl carbonate, dibutyl carbonate, and the like. The cyclic carbonate may be used alone or in combination of two or more. Examples of the cyclic carbonate include ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, and the like, but are not limited thereto.The cyclic carbonate may be used alone or in combination of two or more. Is also good.

The mixed solvent containing a cyclic carbonate and a non-cyclic carbonate contains, in addition to the carbonate, another solvent known as a solvent constituting a non-aqueous electrolyte. Is also good. Examples of the solvent contained in the non-aqueous electrolyte in addition to the carbonate include, for example, γ-butyrolactone, sulfolane, dioxolan, tetrahydrofuran, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,2-dimethoxyethane, 1,2-ethoxy. In addition to methoxyethane, glymes such as methyl glyme, methyl triglyme, methyl tetraglyme, ethyl glyme, ethyl diglyme, and butyl diglyme are exemplified. The solvent is not limited to these, and these solvents may be used alone or as a mixture of two or more.

[0012] As the (ii) a Lewis acid double salt represented by the electrolyte salt Equation (I), for example _{LiBF 4, LiAsF 6, LiPF 6} , but such LiSbF ₆ and the like, but is not limited thereto. Examples of the sulfonic acid electrolyte salt represented by the formula (II) include LiCF ₃ SO ₃ and LiN (CF ₃ S
O ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , LiC (CH ₃ ) (C
F ₃ SO ₂ ) ₂ , LiCH (CF ₃ SO ₂ ) ₂ , LiCH
₂ (CF ₃ SO ₂ ), LiC ₂ F ₅ SO ₃ , LiN (C ₂ F ₅ S
O ₂ ) ₂ , LiB (CF ₃ SO ₂ ) ₂ , LiO (CF ₃ S
O ₂ ) and the like, but are not limited thereto. Further, in addition to the electrolyte salt, an electrolyte salt used in a normal non-aqueous electrolyte, for example, LiClO ₄ , L
iCF ₃ CO ₃ , NaClO ₃ , NaBF ₄ , NaSCN,
KBF ₄ , Mg (ClO ₄ ) ₂ , Mg (BF ₄ ) _{2 and the} like.

By using the sulfonate represented by the formula (II), the adhesiveness of the obtained polymer solid electrolyte is improved, and the interface state between the positive and negative electrodes is further improved. Is corrosive, and this corrosiveness is particularly remarkable when aluminum is used as the positive electrode current collector. The Lewis acid double salt represented by the above formula (I) can suppress the corrosiveness of the sulfonate.

Examples of the non-aqueous electrolyte include at least one Lewis acid double salt composite electrolyte salt of the above formula (I) and a solution in which a sulfonic acid salt of the above formula (II) is dissolved in a non-aqueous solvent. In particular, the concentration of the Lewis acid double salt composite electrolyte salt in the non-aqueous electrolyte is usually 1.0 to 7.0 mol /
Liter, preferably at a rate of 1.0 to 5.0 mol / liter. If it is less than 1.0 mol / liter, a solid electrolyte having sufficient solid strength cannot be obtained. On the other hand, if it exceeds 7.0 mol / liter, it becomes difficult to dissolve the electrolyte salt.
The non-aqueous electrolyte is usually 200% by weight or more, preferably 400% by weight, based on the high molecular weight polymer forming the matrix.
To 900% by weight, particularly preferably 500 to 800% by weight
It is. If it is less than 200% by weight, a sufficiently high ionic conductivity cannot be obtained, and if it exceeds 900% by weight, it is difficult to solidify the non-aqueous electrolyte.

(2) Polymer matrix As the gel electrolyte in the present invention, a thermoplastic gel composition comprising a polymer such as polyvinylidene fluoride, polyacrylonitrile, polyethylene oxide, a solvent and an electrolyte salt;
A gel composition comprising a polysiloxane having an ethylene oxide chain in a side chain or a crosslinked polymer having an ethylene oxide chain in a side chain or a main chain, for example, a polymer matrix formed by cross-linking urethane, acrylic, epoxy or the like, a solvent, and an electrolyte salt. However, a crosslinked polymer gel composition is particularly effective. The crosslinked polymer matrix will be described in detail. The polymerizable compound used in the present invention contains a hetero atom other than carbon such as an oxygen atom, a nitrogen atom, and a sulfur atom in the molecule. Polymer gel electrolyte, for example, a polymerizable compound containing a hetero atom is dissolved in a non-aqueous electrolyte,
It is obtained by a polymerization reaction, and the reaction is preferably performed in an inert gas atmosphere. The type of the polymerizable compound used in the present invention is not particularly limited, and includes a type in which a polymerization reaction such as thermal polymerization and actinic ray polymerization is caused to obtain a polymer. In addition, as described above, the heteroatoms other than carbon present in the obtained polymer solid electrolyte are estimated to have a function of improving the ionic conductivity of the solid electrolyte and improving the strength of the solid electrolyte. You. Hereinafter, the polymerizable compound used in the present invention will be specifically described. As the polymerizable compound, various monomers such as ethylene oxide,
Examples thereof include acrylonitrile, epoxy, vinylidene fluoride, ethylene, styrene, urethane, siloxane, and phosphazene. Particularly preferred are monofunctional and polyfunctional (meth) acrylate monomers and / or prepolymers (hereinafter, (meth) acrylate compounds). Also say. ], But is not limited thereto. In addition, (meth) acrylate in this specification is
Means acrylate or methacrylate.

As the monofunctional acrylate, alkyl (meth) acrylate [methyl (meth) acrylate,
Butyl (meth) acrylate, trifluoroethyl (meth) acrylate, etc.], alicyclic (meth) acrylate,
Hydroxyalkyl (meth) acrylate (hydroxyethyl acrylate, hydroxypropyl acrylate, etc.), hydroxypolyoxyalkylene (oxyalkylene group preferably has 1 to 4 carbon atoms) (meth) acrylate [hydroxypolyoxyethylene (meth) acrylate, hydroxy Polyoxypropylene (meth) acrylate and the like) and alkoxyalkyl (alkoxy group preferably has 1 to 4 carbon atoms) (meth) acrylate (methoxyethyl acrylate, ethoxyethyl acrylate, phenoxyethyl acrylate and the like).
Specific examples of other (meth) acrylates include, for example, methyl ethylene glycol (meth) acrylate,
Alkyl such as ethylethylene glycol (meth) acrylate, propylethylene glycol (meth) acrylate, ethoxydiethylene glycol acrylate, methoxyethylene glycol acrylate, methoxydiethylene glycol methacrylate, methoxytriethylene glycol acrylate, methoxytriethylene glycol methacrylate, and methoxytetraethylene glycol methacrylate Examples thereof include alkyl propylene glycol (meth) acrylates such as ethylene glycol (meth) acrylate, ethyl propylene glycol acrylate, butyl propylene glycol acrylate, and methoxy propylene glycol acrylate.

The (meth) acrylate may contain a heterocyclic group, which includes oxygen, nitrogen,
It is a heterocyclic residue containing a hetero atom such as sulfur. The type of the heterocyclic group contained in the (meth) acrylate is not particularly limited, but for example, a furfuryl group,
Furfuryl (meth) having a tetrahydrofurfuryl group
Acrylate and tetrahydrofurfuryl (meth) acrylate are preferred. Other (meth) acrylates having a heterocyclic group include furfurylethylene glycol (meth) acrylate, tetrahydrofurfurylethylene glycol (meth) acrylate, furfurylpropylene glycol (meth) acrylate, and tetrahydrofurfurylpropylene glycol (meth) acrylate And alkylene glycol acrylates having a furfuryl group or a tetrahydrofurfuryl group.

Examples of the polyfunctional (meth) acrylate compound include a monomer or a prepolymer having two or more (meth) acryloyl groups. Examples of the functional (meth) acrylate compound include ethylene glycol dimethacrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, and triethylene glycol di (meth) acrylate. Examples include methylolpropane tri (meth) acrylate, pentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, EO-modified trimethylolpropane triacrylate, and PO-modified trimethylolpropane triacrylate.

The molecular weight of the (meth) acrylate compound is usually less than 500, preferably 300 or less. In addition, the molecular weight of the (meth) acrylate compound is 500
Above, the non-aqueous solvent easily oozes from the obtained solid electrolyte. The (meth) acrylate compounds may be used alone, or two or more of them may be used in combination. The use ratio of the (meth) acrylate compound is 50% by weight or less, preferably 5 to 40% by weight, more preferably 10 to 30% by weight based on the total weight of the nonaqueous electrolyte.

The polymerizable compound used in the present invention may be a combination of a monofunctional monomer and a polyfunctional monomer. In particular, a combination of a monofunctional monomer and a polyfunctional monomer that can form a crosslinked polymer matrix is preferable. Further, when a trifunctional monomer is used as the polyfunctional monomer, a crosslinked polymer matrix having higher ionic conductivity and sufficient strength and viscoelasticity as a solid electrolyte for an electrochemical device can be obtained. That is, since the polymer matrix is a cross-linked polymer matrix, the above-mentioned ionic conductivity polymer solid electrolyte having better retention of the electrolyte solution is obtained, and the reliability and ionic conductivity are extremely high, and A solid polymer electrolyte for an electrochemical device having a solid strength sufficient for use as an electrolyte can be obtained, and a secondary battery having a good interface between a positive electrode and a negative electrode can be obtained as an electrochemical device.

(3) Polymerization initiator As the polymerization initiator, carbonyl compounds (benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, α-phenylbenzoin, etc.), anthraquinones ( Anthraquinone, methylanthraquinone, chloranthraquinone, etc.), other compounds (benzyl, diacetyl, acetophenone, benzophenone, methylbenzoylformate, etc.), sulfur compounds (diphenylsulfide, dithiocarbamate, etc.), polycondensed ring hydrocarbon halides ( α-chloromethylnaphthalene, etc.), pigments (acrylflavin, fluorescein, etc.), metal salts (iron chloride, silver chloride, etc.), onium salts (p-methoxybenzenediazonium) , Hexafluorophosphate, diphenyl eye odometer bromide,
And a photopolymerization initiator such as triphenylsulfonium. These can be used alone or as a mixture of two or more. Preferred photopolymerization initiators are carbonyl compounds, sulfur compounds and onium salts.

Examples of the thermal polymerization initiator include azobisisobutyronitrile, azobisisovaleronitrile, benzoyl peroxide, lauroyl peroxide, ethyl methyl ketone peroxide, bis- (4-t-butylcyclohexyl) peroxydicarbonate. And peroxydicarbonates such as diisopropylperoxydicarbonate. Further, a polymerization initiator such as dimethylaniline, cobalt naphthenate, sulfinic acid, and mercaptan can also be used in combination. Further, a sensitizer and a storage stabilizer can be used together if necessary. Further, the above-mentioned thermal polymerization initiator, photopolymerization initiator and the like can be used in combination.

Preferred sensitizers are urea, nitrile compounds (N, N-disubstituted-p-aminobenzonitrile, etc.) and phosphorus compounds (tri-n-butylphosphine, etc.). Quaternary ammonium chloride, benzothiazole and hydroquinone are preferred. The amount of the polymerization initiator used is usually 0.1
10 to 10% by weight, preferably 0.5 to 7% by weight. The use amount of the sensitizer and the storage stabilizer is usually 0.1 to 5 parts by weight based on 100 parts by weight of the polymerizable compound.

(4) Characteristics of Polymer Solid Electrolyte The viscoelastic solid electrolyte of the present invention has high ionic conductivity,
Low glass transition temperature (Tg), high temperature stability, easy processability,
It has low creep properties and tackiness, and is excellent in liquid retention while containing a large amount of electrolyte, and excellent in shape retention. The ionic conductivity of the solid electrolyte of the present invention at 25 ° C. by the AC impedance method is greatly affected by the conductivity of the non-aqueous electrolyte which is a component of the electrolyte, and does not exceed the conductivity. There is almost no decrease in the conductivity, and usually 1/10 ⁴ to
It has 1/10 ² S / cm. Dynamic viscoelasticity tester for solid electrolyte of the present invention [MR-300 Solid Liquid Meter Co., Ltd.
The elastic modulus by rheology is usually 10 ⁶ dyne / cm ² or less, preferably 10 ² to 10 ⁵ dyne / cm ² , more preferably 10 ³ to 10 ⁵ dyne / cm ² , and Tg is -30 ° C. or less. At 100.degree. C. The elongation is not less than 20% and does not break to a maximum of about 400% and has a resilience to stretching deformation. Also,
It does not break even when bent 180 degrees.

The solid electrolyte of the present invention is a creep meter [RE-3305, manufactured by Yamaden Co., Ltd .;
m ² , a load of 30 g] was used to measure the change over time in the amount of strain, and the amount of strain did not change with time, and had low creep characteristics. Load 25g / using creep meter
Even if the solid electrolyte is compressed in cm ² , the electrolyte contained therein does not flow out. Further, the viscoelastic body exhibits high tackiness, and when the viscoelastic bodies are bonded to each other, even if the viscoelastic bodies are to be separated, the material is broken, and the viscoelastic bodies are not separated from the bonding surface.

Next, the case where the polymer electrolyte of the present invention is used as a battery electrolyte will be described in detail. In general, a battery includes a positive electrode made of a positive electrode active material, a negative electrode made of a negative electrode active material, a diaphragm, and an electrolyte. By using the solid electrolyte of the present invention as an electrolyte in this battery, an unprecedented advantageous battery can be obtained.

That is, when the solid electrolyte of the present invention is applied to a battery, the solid electrolyte of the present invention itself can also function as a diaphragm, but the electric field between the electrodes is made uniform, and the strength is improved. In order to improve the reliability of the obtained battery, it is preferable that the battery is integrated with a diaphragm. In particular, such consideration is necessary for a secondary battery. In particular, when the polymerizable compound of the present invention is used, integration of the membrane with the solid electrolyte is easy, and the solid electrolyte is formed directly in the battery container having the membrane, or the solid electrolyte forming composition is formed in the membrane. It can be integrated by impregnating the substance and performing a polymerization reaction.

Further, by polymerizing a polymerizable compound for forming a solid electrolyte containing an inorganic or organic filler such as a glass fiber or a carbon fiber polymer stretched product, it is possible to obtain a stronger solid polymer that does not need to be integrated with a diaphragm. An ion conductive solid electrolyte can be obtained. Further, the solid electrolyte formed by this formulation is a viscoelastic body by itself, and when forming an electrochemical element such as a battery, the ionic conductivity is reduced by 1 /.
The elastic modulus is kept at 10 ² dyne while keeping it at 10 ⁴ S / cm or more.
/ Cm ² or more. In particular, the ionic conductivity is 1 /
In the case of 10 ³ S / cm or more, the elastic modulus is 10 ² to 10 ⁵ dy.
ne / cm ² , and can effectively work as an electrochemical element. The solid polymer electrolyte of the present invention can be used as a solid polymer electrolyte layer in electrochemical devices such as batteries, capacitors, sensors, electrochromic devices, and semiconductor devices.

[2. Positive electrode] (1) Positive electrode active material The positive electrode active material used in the battery of the present invention is Ti.
Transition metal oxides such as S ₂ , MoS ₂ , Co ₂ S ₅ V ₂ O ₅ , MnO ₂ , and CoO ₂ , transition metal chalcogen compounds, and complexes thereof with Li (Li composite oxide; LiMn
O _2, LiMn ₂ O _4, etc. LiCoO _2, LiNiO _2), one-dimensional graphite compound which is the thermal polymerization of organic fluoride carbon, graphite or 1/10 ² S
/ Cm or more conductive polymers having an electrical conductivity of not less than, specifically, polymers such as polyaniline, polypyrrole, polyazulene, polyphenylene, polyacetylene, polyphthalocyanine, poly-3-methylthiophene, polypyridine, polydiphenylbenzidine, and the like. Derivatives may be used, but it is preferable to use a conductive polymer that exhibits high cycle characteristics even at a discharge depth of 100% and is relatively resistant to overdischarge as compared with inorganic materials. In addition, since the conductive polymer is a plastic in terms of moldability and processability, it can make use of an unprecedented feature. Although a conductive polymer has the above advantages, a secondary battery using a conductive polymer as a positive electrode has a low volume energy density due to a low density of an active material, and an electrode in an electrolytic solution. A sufficient amount of electrolyte is required for the reaction, and the concentration of the electrolyte changes greatly with the charge / discharge reaction, causing a large change in the liquid resistance and other factors. There is a problem that becomes. This is disadvantageous in improving the energy density.

On the other hand, as the active material having a high volume energy density, it is conceivable to use an inorganic chalcogenide compound or an inorganic oxide for the positive electrode. It is slow, difficult to rapidly charge and discharge, poor in reversibility to overdischarge, and has a problem that the cycle life is shortened. In addition, since it is difficult to mold the inorganic active material as it is, pressure molding is often performed using a tetrafluoroethylene resin powder or the like as a binder, but in such a case, the mechanical strength of the electrode is sufficient. In addition, when lithium ions are excessively accumulated in overdischarge, the crystal structure is destroyed, and the function as a secondary battery is not achieved.

In order to solve the above problems, it is conceivable to use an organic and inorganic composite active material.
In this case, the polymer active material used is required to exhibit high electrical conductivity due to electrochemical doping, and the electrode material is required to have electrical conductivity of 1/10 ² S / cm or more. These polymer materials have a high electrical conductivity and a current collecting ability, have a binding ability as a polymer, and also function as an active material. In addition, since the conductive polymer is insulated at a low potential, even when the composite positive electrode is in an overdischarged state, the conductive polymer is insulated, so that the lithium ions contained in the inorganic active material contained therein are more than necessary. And prevents the crystal structure of the inorganic active material from being destroyed. As a result, an electrode that is substantially resistant to overdischarge can be configured.

Examples of the conductive polymer used for such a composite electrode include redox active materials such as polyacetylene, polypyrrole, polythiophene, polyaniline, and polydiphenylbenzidine. Particularly, a remarkable effect is exerted on nitrogen-containing compounds. Can be seen. These conductive polymer materials are required to have high ionic conductivity not only in conductivity but also in ion diffusivity. Further, the inorganic active material used for the composite positive electrode preferably has excellent potential flatness. Specifically, V, Co, Mn, Ni, or a transition metal oxide or a composite oxide of the transition metal and an alkali metal is preferably used. Examples can be given.

(2) Positive Electrode Current Collector The positive electrode current collector used in the present invention is, for example, a metal sheet such as stainless steel, gold, platinum, nickel, aluminum, molybdenum or titanium, a metal foil, a metal net, or a punching metal. , Expanded metal, or a mesh or nonwoven fabric made of metal-plated fiber, metal-deposited wire, metal-containing synthetic fiber, or the like. Among them, aluminum, considering electrical conductivity, chemical, electrochemical stability, economy, workability, etc.
It is preferable to use stainless steel. Aluminum is more preferred because of its light weight and electrochemical stability. Furthermore, the surfaces of the positive electrode current collector layer and the negative electrode current collector layer used in the present invention are preferably roughened. By performing the surface roughening, the contact area of the active material layer is increased, the adhesion is improved, and the impedance as a battery is reduced. In the preparation of an electrode using a coating solution, a roughening treatment can greatly improve the adhesion between the active material and the current collector.

As the surface roughening treatment, there are polishing with an emery paper, blasting, and chemical or electrochemical etching, whereby the current collector can be roughened. In particular, in the case of stainless steel, blast processing is preferable, and in the case of aluminum, etched aluminum is preferable. Since aluminum is a soft metal, an effective surface roughening cannot be performed by blasting, and aluminum itself is deformed. On the other hand, the etching treatment can effectively roughen the surface in the order of micron without deforming the aluminum and greatly reducing its strength, and it is possible to roughen the aluminum, This is the most preferable method for surface roughening.

[3. Negative electrode] A carbonaceous material is used as the negative electrode material used in the battery of the present invention. Examples of the carbonaceous negative electrode active material include graphite, pitch coke, synthetic polymers, and fired bodies of natural polymers. In the present invention, synthetic polymers such as phenol and polyimide, and natural polymers are reduced in a reducing atmosphere at 400 to 800 ° C. Insulating or semiconductive carbon body, coal, pitch, obtained by firing in
Conductive carbon, coke, pitch, synthetic polymer, and natural polymer obtained by firing a synthetic polymer or a natural polymer in a reducing atmosphere at 800 to 1300 ° C.
Those obtained by firing at a temperature of 000 ° C. or more in a reducing atmosphere, and graphite-based carbon bodies such as natural graphite are used. Among them, carbon bodies and natural graphite obtained by firing mesoface pitch and coke in a reducing atmosphere at 2500 ° C. or more have excellent potential flatness and favorable electrode characteristics, and these composites are also used as negative electrodes. Has characteristics. The carbon body is formed into a sheet by a wet papermaking method from the carbon body and the binder, or by a coating method from a coating material in which an appropriate binder is mixed with a carbon material. The electrode can be manufactured by supporting the electrode on a current collector as required by a method such as application, adhesion, or pressure bonding.

[4. Separator] In the battery of the present invention, a separator may be used. As the separator, it is preferable to use a separator that has low resistance to ion movement of the electrolyte solution and is excellent in solution retention. Examples of such separators include glass fiber, filter, polyester, Teflon, polyflon, polypropylene,
Non-woven fabric filters made of polymer fibers such as polyethylene, and non-woven fabric filters made of a mixture of glass fibers and those polymer fibers can be given.

The battery of the present invention can be manufactured by using a solid electrolyte comprising the viscoelastic body comprising a high molecular weight polymer and a non-aqueous electrolyte instead of the solid electrolyte in a conventional battery. Since the solid electrolyte of the present invention can be formed by polymerizing a polymerizable compound dissolved in a non-aqueous electrolyte and converting the reaction solution into a viscoelastic material having high flexibility, it can be formed on an electrode, on a diaphragm or It is preferable to form by performing a polymerization reaction directly in the electrode. That is, the battery element such as an electrode or a diaphragm is impregnated with the composition for forming a solid electrolyte,
It is preferable to form the viscoelastic body by polymerization means such as heating or irradiation with actinic rays, and to integrate the solid electrolyte and the battery element. The integration of each battery element and the solid electrolyte may be integrated for each battery element, but a combination of a positive electrode and a diaphragm, a combination of a negative electrode and a diaphragm, or a combination of a positive electrode, a diaphragm, and a negative electrode may be combined with a solid electrolyte. They may be integrated. When the battery element and the solid electrolyte are integrated as described above, the electrode reaction and the movement of ions at the positive electrode and the negative electrode can smoothly proceed, and the internal resistance of the battery can be greatly reduced.

[0038]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto.
In the following, parts and% indicate parts by weight and% by weight, respectively. The non-aqueous solvent and the electrolyte salt were sufficiently purified to have a water content of 20 ppm or less, and a battery grade of deoxygenation and denitrification was used.
All operations were performed under an inert gas atmosphere. The ionic conductivity was measured by using a SUS cylindrical container (inner diameter 20 mm) whose inner surface except the bottom surface was covered with insulating tape as a counter electrode.
The container was filled with a solid electrolyte, and a column made of SUS having a diameter of 18 mm as a working electrode was pressure-bonded to the surface of the solid electrolyte. Measurements at 0 ° C and 25 ° C
(Cell for measuring ionic conductivity).

Example 1 Ion-Conducting Polymer Solid Electrolyte (I) Non-aqueous solvent: 2.0 mol / l L dissolved in ethylene carbonate / diethyl carbonate (2/8: volume ratio)
In 80.0 parts of an electrolyte solution of an iPF ₆ solution, 20.0 parts of ethyl diethylene glycol methacrylate as a monomer and 0.05 of benzoin isopropyl ether as a photoinitiator
6 parts were added, mixed and dissolved to prepare a photopolymerizable solution. This solution was put into a cell for measuring ion conductivity, and irradiated with a high-pressure mercury lamp equipped with a cold mirror concentrator to solidify the electrolyte. When this ionic conductivity was measured, it was 6.6 × 10 ^−3.
S / cm (25 ° C.) and an elastic modulus of 1.9 × 10 ³ d
yne / cm ² . Further, the ionic conductivity was measured at 0 ° C. and found to be 3.0 × 10 ⁻³ S / cm.

Comparative Example 1 The electrolyte was solidified in the same manner as in Example 1 except that the non-aqueous solvent was changed to ethylene carbonate / diethyl carbonate (7/3: volume ratio). This ion conductivity is 2.1 × 10 ^−3.
S / cm (25 ° C.), elastic modulus is 3.4 × 10 ³ dyne
/ Cm ² and the ionic conductivity at 0 ° C. is 0.8 × 10
^-3 S / cm ² , and it was found that the ionic conductivity was inferior, but the ionic conductivity was particularly poor at low temperatures, although the elastic modulus was excellent.

Comparative Example 2 An electrolyte was solidified in the same manner as in Example 1 except that the electrolyte salt was LiClO ₄ . The ionic conductivity is 1.1 × 10
^-3 S / cm (25 ° C.), elastic modulus is 0.8 × 10 ³ dyn
e / cm ² and the ionic conductivity at 0 ° C. is 0.5 × 1
0 ^-3 S / cm ² , and found to be inferior in elastic modulus and ionic conductivity, and particularly in ionic conductivity at low temperatures.

Example 2 Ion-conductive polymer solid electrolyte (II) 1.8 mol / l L dissolved in a non-aqueous solvent: ethylene carbonate / dimethyl carbonate (4/6: volume ratio)
iN (CF ₃ SO ₂ ) ₂ solution and 0.2 mol / l Li
Ethoxydiethylene glycol methacrylate 20.0 as a monomer was added to 80.0 parts of a mixed electrolyte of a BF ₄ solution.
And 0.056 parts of bis (4-t-butylcyclohexyl) peroxydicarbonate as a thermal polymerization initiator were added, mixed and dissolved to prepare a thermopolymerizable solution. Was solidified. When this ionic conductivity was measured, it was 5.0 × 10 ⁻³ S / cm (25 ° C.) and the elastic modulus was 5.2 × 10 ³ dyne / cm ² , and the adhesiveness was particularly excellent. The ionic conductivity at 0 ° C. is 2.4 ×
It was 10 ^-3 S / cm.

Comparative Example 3 A nonaqueous solvent: ethylene carbonate / dimethyl carbonate (8/2: volume ratio), and the electrolyte was solidified in the same manner as in Example 2 except that LiClO ₄ was used instead of the sulfonate electrolyte. . This ionic conductivity is 0.9 × 10 ⁻³ S /
cm (25 ° C.), 0.4 × 10 ⁻³ S / cm (0 ° C.), the elastic modulus is 6.6 × 10 ³ dyne / cm ² , and although the elastic modulus is excellent, it is brittle and has poor adhesion. It was also found that the ionic conductivity was remarkably inferior at both 25 ° C. and 0 ° C.

Example 3 Ion conductive polymer solid electrolyte (III) Non-aqueous solvent: 2.0 mol / l Li dissolved in ethylene carbonate / dimethyl carbonate (3/7: volume ratio)
PF ₆ ethoxy glycol acrylate 15.8 electrolyte 84.0 parts of the solution as a monofunctional monomer
Parts, 0.2 parts of trimethylolpropane triacrylate as a polyfunctional monomer and 0.056 parts of benzoin isopropyl ether as a photoinitiator were added, mixed and dissolved to prepare a photopolymerizable solution. This solution was put into a cell for measuring ion conductivity, and irradiated with a high-pressure mercury lamp equipped with a cold mirror concentrator to solidify the electrolyte. The measured ionic conductivity was 6.4 × 10 ⁻³ S / cm (25 ° C.), and the elastic modulus was 3.6 × 10 ³ dyne / cm ² . Further, when the ionic conductivity was measured at 0 ° C., it was 2.8 × 10 ^−3.
S / cm.

Comparative Example 4 The electrolyte was solidified in the same manner as in Example 3 except that the non-aqueous solvent was changed to ethylene carbonate / dimethyl carbonate (6/4: volume ratio). The measured ionic conductivity was 2.2 × 10 ⁻³ S / cm (25 ° C.), and the elastic modulus was 4.8 × 10 ³ dyne / cm ² . Further 0
0.8 × 10 ⁻³ S
/ Cm and excellent in elastic modulus, but poor in ionic conductivity.

Example 4 Ion-conductive polymer solid electrolyte (IV) 1.8 mol / l LiN (CF ₃ SO) dissolved in non-aqueous solvent: propylene carbonate / ethylene carbonate / diethyl carbonate (1/3/6: volume ratio) ₂ ) 14.0 parts of ethoxydiethylene glycol acrylate as a monofunctional monomer, 0.2 parts of trimethylolpropane triacrylate as a polyfunctional monomer, and benzoneisopropyl as a photoinitiator in 86 parts of an electrolyte solution of ₂ solution and 0.2 mol / l LiPF ₆ 0.056 parts of ether was mixed and dissolved to prepare a photopolymerizable solution. Thereafter, the electrolyte was solidified in the same manner as in Example 1. This ion conductivity is 3.6 × 10
^-3 S / cm (25 ° C.), elastic modulus is 4.0 × 10 ³ dyn
e / cm ² and excellent tackiness.
Further, the ionic conductivity at 0 ° C. was 2.0 × 10 ⁻³ S / cm.

Comparative Example 5 Only ethoxydiethylene glycol acrylate, which is a monofunctional monomer, was 14.0 parts, 2.0 mol / mol.
The electrolytic solution was solidified in the same manner as in Example 4 except that 86 parts of the electrolytic solution of 1LiCF ₃ SO ₃ was used. The ionic conductivity is 3.8 × 10 ⁻³ S / cm (25 ° C.), and the elastic modulus is 5.
It was 3 × 10 ² dyne / cm ² . The ionic conductivity at 0 ° C. was 2.3 × 10 ⁻³ S / cm. Although the ionic conductivity was excellent, the elastic modulus was lowered.

Example 5 Preparation of Electrochemical Device (I) (Positive electrode) 3 parts by weight of polyvinylidene fluoride were dissolved in 38 parts by weight of N-methylpyrrolidone, and LiCoO was used as an active material.
Adding graphite 9 parts by weight dispersed in an inert atmosphere with a homogenizer as ₂ 50 parts by weight, the conductive agent, to prepare a positive electrode coating material. This was applied on a 20 μm Al foil using a wire bar in the air, and dried at 125 ° C. for 30 minutes to produce an electrode having a thickness of 60 μm. This is the positive electrode,
The counter electrode was a Li plate, in which the photopolymerizable solution prepared in Example 3 was permeated, irradiated with a high-pressure mercury lamp, and the electrolyte was solidified.
A charge / discharge test was performed. HJ-2 Hokuto Denko charge / discharge test
Using a 01B charge / discharge measurement device, the battery was charged at a current of 0.4 mA until the battery voltage reached 3.7 V. After a pause for one hour,
At a current of 0.4 mA, the battery voltage is discharged to 2.5 V,
Hereinafter, this charge / discharge was repeated. At this time, the discharge capacity density at the initial and 50th cycles was 318 mAh / cc, 309 m
Ah / cc. The initial discharge capacity density at 0 ° C. was 223 mAh / cc.

Example 6 Preparation of Electrochemical Element (II) (Negative electrode) 2 parts by weight of polyvinylidene fluoride were dissolved in 58 parts by weight of N-methylpyrrolidone, and 40 parts by weight of a coke calcined product at 2500 ° C. were added. The mixture was mixed and dispersed under an inert atmosphere by a roll mill method to prepare a coating material for a negative electrode. This was applied to a 20 μm copper foil using a wire bar in the air, and 10
It was dried at 0 ° C. for 15 minutes to produce an electrode having a thickness of 60 μm. This was used as a negative electrode, and the counter electrode was used as a Li plate. The photopolymerizable solution prepared in Example 1 was infiltrated, irradiated with a high-pressure mercury lamp, the electrolyte was solidified, and a charge / discharge test was performed. The charge / discharge test was performed using a Hokuto Denko HJ-201B charge / discharge measurement device at a constant current of 1.5 mA at a constant current until the voltage became 0 V, and thereafter, a constant voltage charge for 3 hours. The battery was discharged by the current to 0.8 V, and the charging and discharging were repeated thereafter. At this time, the discharge capacity densities at the initial and 50th cycles were 265 mAh / cc and 260 mAh / cc. The initial discharge capacity density at 0 ° C. is 186 mAh.
/ Cc.

Comparative Example 6 A positive electrode was prepared in the same manner as in Example 5 except that the photopolymerizable solution prepared in Comparative Example 4 was used, and the initial discharge capacity at 0 ° C. was measured to be 127 mAh / cc. Further, a negative electrode was prepared in the same manner as in Example 6 except that the photopolymerizable solution prepared in Comparative Example 4 was used, and the initial discharge capacity at 0 ° C. was 106 mAh / cc. As described above, the deterioration of the initial discharge capacity at a low temperature was particularly remarkable.

Example 7 Preparation of Electrochemical Element (III) (Positive electrode) 10 parts by weight of polyaniline synthesized by chemical polymerization using sulfuric acid and ammonium persulfate as an oxidizing agent
Crystalline V ₂ O ₅ dissolved in 50 parts by weight of methylpyrrolidone
50 parts by weight of graphite and 6 parts by weight of graphite were added and mixed and dispersed using a homogenizer under an inert atmosphere to prepare a coating for a positive electrode. This was put in the air for 20μ using a wire bar.
It was applied on a mAl foil and dried at 100 ° C. for 15 minutes to produce an electrode having a thickness of 60 μm. (Negative electrode) The negative electrode produced in Example 6 was used. The photopolymerizable solution prepared in Example 3 was permeated into the positive electrode and the negative electrode, and irradiated with a high-pressure mercury lamp to solidify the electrolytic solution. These were laminated and three sides were heat-sealed while uniformly applying pressure to the power generation element portion, and the other side was sealed under reduced pressure to produce a battery. In the charge / discharge test, the battery characteristics were evaluated in the same manner as in Example 6 using a Hokuto Denko HJ-201B charge / discharge measurement device. At this time, the discharge capacity at the initial and 50th cycle is 1
0.9 mAh and 10.4 mAh. The discharge capacity at 0 ° C. was 7.7 mAh. A battery with less deterioration at low temperatures could be manufactured.

[0052]

【The invention's effect】

1. Claims 1 and 2 Both the elastic modulus and the ionic conductivity are improved. Further, an ion-conductive polymer solid electrolyte in which a decrease in ionic conductivity at a low temperature was suppressed was obtained. 2. [Claim 3] In addition to the above effects, an ion-conductive polymer solid electrolyte having good adhesiveness and good retention of the electrolytic solution was obtained. 3. Claims 4, 5, and 6 An all-solid-state electrochemical device can be manufactured without liquid leakage, and an electrochemical device and a secondary battery with less deterioration in cycle characteristics and excellent low-temperature characteristics can be obtained.

Claims (6)

[Claims] 1. A solid polymer electrolyte comprising a polymer as a matrix, wherein the solid polymer electrolyte has at least the following formula (I): LiXFn (I) (where X is B, P, As, Sb And when X is B, n is 4 and when P, As, Sb is 6, the Lewis acid double salt (A) and at least the cyclic carbonate and the acyclic carbonate (B) are An ion-conductive polymer solid electrolyte, wherein the volume ratio of the cyclic carbonate / acyclic carbonate is less than 1. 2. A compound represented by the following formula (II): LiX (SO ₂ R ₃ ) n (II) wherein X is an N, C, B, O or CR ₄ group (R ₄ is an alkyl group). R ₃ is CF ₃ or C ₂ F ₅ , and n is an integer of 1 to 3. The ion-conductive polymer solid electrolyte according to claim 1, further comprising a sulfonate represented by the following formula: 3. The ion-conductive polymer solid electrolyte according to claim 1, wherein the polymer matrix is a crosslinked polymer matrix. 4. An electrochemical device comprising the ion-conductive polymer solid electrolyte according to claim 1, 2 or 3. 5. The electrochemical device according to claim 4, wherein the ion-conductive polymer solid electrolyte is formed integrally with at least one component of the electrochemical device. 6. The electrochemical device according to claim 4, wherein the electrochemical device is a non-aqueous secondary battery.