JP3458049B2 - Ion conductive polymer solid electrolyte and electrochemical device containing the solid electrolyte - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a 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, so not only leakage of the electrolytic solution and drying of the inside of the battery due to volatilization of the solvent occur, but also in the battery container, a diaphragm is formed due to the bias of the electrolytic solution. It becomes partially dry, which causes an increase in internal impedance or an internal short circuit. Further, no solid electrolyte for display of an electrochromic device has been obtained which sufficiently satisfies the operating speed. It has been proposed to use a polymer solid electrolyte as a method for solving these drawbacks. A specific example thereof is 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 processability, but its ionic conductivity is 1 / at room temperature. 105 S /
cm, which is about 3 digits lower than ordinary non-aqueous electrolytes.

Further, in order to improve the ionic conductivity of the polymer solid electrolyte, a method of dissolving an organic electrolytic solution in a polymer to form a semi-solid state (Japanese Patent Laid-Open No. 54-104541) and an electrolyte are added. A method in which a liquid monomer is polymerized to form a crosslinked polymer containing an electrolyte (JP-A-63-945).
No. 01) is proposed. However, the solid electrolyte obtained by the former method includes 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. Including the problem.

Gels have recently attracted attention as a solid electrolyte having excellent ionic conductivity and uniformity and having sufficient solid strength for use as a solid electrolyte for electrochemical devices. The reason is that the ionic conductivity is high, the uniformity is excellent, a solid strength sufficient for use as a solid electrolyte for an electrochemical device can be obtained, and the processability is high, which improves the reliability of the electrochemical device. This is because it is useful, and in particular, batteries having excellent repeatability can be obtained.
Further, 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 ionic conductivity is high, but the solid strength is high. Is not sufficient, and the ion conductivity is drastically reduced at low temperature, and there is no one satisfying these various requirements.

[0005]

DISCLOSURE OF THE INVENTION In order to solve the above problems found in conventional solid electrolytes having a polymer as a matrix, the present invention is excellent in ionic conductivity and uniformity and is solid for electrochemical devices. Provided are a solid electrolyte having a polymer having sufficient solid strength for use as an electrolyte and having good ionic conductivity particularly at low temperature, and an electrochemical device 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 polymer solid electrolyte having a polymer as a matrix (hereinafter, also referred to as polymer solid electrolyte), at least the polymer solid electrolyte has the following formula (I).

Embedded image LiXFn (I) (wherein X is B, P, As, Sb, n is 4 when X is B, and 6 when P, As, Sb). An ion conductive polymer containing a Lewis acid double salt (A) and a cyclic carbonic acid ester and an acyclic carbonic acid ester (B), and the volume ratio of the cyclic carbonic acid ester / acyclic carbonic acid ester is less than 1. By providing a solid electrolyte, the above-mentioned problems of the prior art are solved.

That is, in the present invention, a mixed solvent having at least a cyclic carbonic acid ester and an acyclic carbonic acid ester (B) in the polymer solid electrolyte in a volume ratio of less than 1 and a Lewis acid compound represented by the above formula (I) are used. By containing a salt, without degrading the elastic modulus of the solid polymer electrolyte,
Electrochemistry that can improve ionic conductivity, especially at low temperature, has very high reliability and ionic conductivity, and has sufficient solid strength for use as a solid electrolyte. It was found that a polymer solid electrolyte for devices can be obtained, and the present invention could be reached.

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 C ₂ F ₅ ; Yes, n is 1-3
Is an integer. ] By further containing a sulfonate represented by the above, the above effect can be further improved.

In the solid electrolyte of the present invention, a polymerizable compound is dissolved in the nonaqueous electrolytic solution to cause a polymerization reaction, or a polymer obtained by polymerizing the polymerizable compound is added to the nonaqueous electrolytic solution. It can also be formed by impregnating with a liquid. In this case, the polymerizable compound is heat-polymerizable,
Those exhibiting polymerizability with active rays such as light, ultraviolet rays, electron rays, γ rays, and X rays are used. The solid polymer electrolyte is preferably formed by the polymerization reaction in an inert gas atmosphere. By carrying out in an inert gas atmosphere, a polymer solid electrolyte excellent in ionic conductivity, strength and the like can be obtained as compared with the case of manufacturing in the air.

The method for producing the solid polymer electrolyte of the present invention, its characteristics and its constitution will be described in detail below. [1. Polymer Solid Electrolyte] (1) Non-Aqueous Electrolyte Solution (i) Solvent As a solvent constituting the non-aqueous electrolyte solution, by using a mixed solvent containing a cyclic carbonic acid ester and a non-cyclic carbonic acid ester as described above, ions A solid electrolyte having improved conductivity and elastic modulus can be obtained. Examples of the acyclic carbonic acid ester include dimethyl carbonic acid ester, diethyl carbonic acid ester, ethylmethyl carbonic acid ester, dipropyl carbonic acid ester, diisopropyl carbonic acid ester, dibutyl carbonic acid ester, and the like, but are not limited thereto, and The cyclic carbonic acid ester may be used alone or in combination of two or more kinds. Examples of the cyclic carbonic acid ester include, but are not limited to, ethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate, and the cyclic carbonic acid ester may be used alone or in combination of two or more kinds. Is also good.

The mixed solvent containing the cyclic carbonic acid ester and the non-cyclic carbonic acid ester contains, in addition to the carbonic acid ester, another solvent known as a solvent constituting the non-aqueous electrolytic solution. Is also good. Examples of the solvent contained in the non-aqueous electrolytic solution in addition to the carbonic acid ester include γ-butyrolactone, sulfolane, dioxolane, tetrahydrofuran, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,2-dimethoxyethane, 1,2-ethoxy. In addition to methoxyethane, glymes such as methyl glyme, methyl triglyme, methyl tetraglyme, ethyl glyme, ethyl diglyme, butyl diglyme and the like can be mentioned. The solvent is not limited to these, and these solvents may be used alone or in combination 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 above 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 ), etc., but not limited thereto. Further, in addition to the electrolyte salt, an electrolyte salt used in a normal non-aqueous electrolyte, such as LiClO ₄ , L
iCF ₃ CO ₃ , NaClO ₃ , NaBF ₄ , NaSCN,
Examples thereof include KBF ₄ , Mg (ClO ₄ ) ₂ and Mg (BF ₄ ) ₂ .

By using the sulfonate represented by the above formula (II), the tackiness of the obtained polymer solid electrolyte is improved and the interfacial state between the positive and negative electrodes is further improved. Has corrosiveness, 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 those prepared by dissolving at least one Lewis acid double salt composite electrolyte salt of the above formula (I), and further dissolving the sulfonate salt of the above formula (II) in a non-aqueous solvent. In particular, the concentration of the Lewis acid double salt composite electrolyte salt in the non-aqueous electrolytic solution is usually 1.0 to 7.0 mol / min in the non-aqueous solvent.
L, preferably 1.0 to 5.0 mol / l. If it is less than 1.0 mol / liter, a solid electrolyte having sufficient solid strength cannot be obtained. Further, 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.
~ 900% by weight, particularly preferably 500-800% by weight
Is. If it is less than 200% by weight, sufficiently high ionic conductivity cannot be obtained, and if it exceeds 900% by weight, solidification of the non-aqueous electrolyte becomes difficult.

(2) Polymer Matrix As the gel electrolyte in the present invention, a thermoplastic gel composition comprising a polymer such as polyvinylidene fluoride, polyacrylonitrile and polyethylene oxide, a solvent and an electrolyte salt,
Examples include a polysiloxane having an ethylene oxide chain as a side chain or a crosslinked polymer having an ethylene oxide chain as a side chain or a main chain, for example, a gel composition comprising a polymer matrix formed by crosslinking urethane, acryl, epoxy, etc., a solvent, and an electrolyte salt. However, the crosslinked polymer gel composition is particularly effective. The cross-linked polymer matrix will be described in detail. The polymerizable compound used in the present invention has a hetero atom other than carbon such as oxygen atom, nitrogen atom, and sulfur atom in its 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 carried out in an inert gas atmosphere. Further, the type of the polymerizable compound used in the present invention is not particularly limited, and includes those which cause a polymerization reaction such as thermal polymerization and actinic ray polymerization to obtain a polymer. Further, as described above, heteroatoms other than carbon present in the obtained polymer solid electrolyte are estimated to have a function of improving the ion conductivity of the solid electrolyte and also improving the strength of the solid electrolyte. It 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, and particularly preferably monofunctional and polyfunctional (meth) acrylate monomers and / or prepolymers (hereinafter referred to as (meth) acrylate compounds). Also say. ], But is not limited thereto. In addition, the (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 (the carbon number of the alkoxy group is preferably 1 to 4) (meth) acrylate (methoxyethyl acrylate, ethoxyethyl acrylate, phenoxyethyl acrylate and the like).
Specific examples of other (meth) acrylates include, for example, methylethylene 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, methoxytetraethylene glycol mecrylate 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, and the heterocyclic group includes oxygen, nitrogen,
A heterocyclic residue containing a hetero atom such as sulfur. The kind of the heterocyclic group contained in this (meth) acrylate is not particularly limited, but for example, a furfuryl group,
Furfuryl (meta) having tetrahydrofurfuryl group
Acrylate and tetrahydrofurfuryl (meth) acrylate are preferred. Other (meth) acrylates having a heterocyclic group include furfuryl ethylene glycol (meth) acrylate, tetrahydrofurfuryl ethylene glycol (meth) acrylate, furfuryl propylene glycol (meth) acrylate, tetrahydrofurfuryl propylene glycol (meth) acrylate. And alkylene glycol acrylates having a furfuryl group or a tetrahydrofurfuryl group.

Examples of polyfunctional (meth) acrylate compounds include monomers or prepolymers 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 thereof 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. The molecular weight of the (meth) acrylate compound is 500.
In the above case, the non-aqueous solvent easily exudes from the obtained solid electrolyte. The (meth) acrylate compound may be used alone, or two or more kinds may be mixed and used. The (meth) acrylate compound is used in an amount of 50% by weight or less, preferably 5 to 40% by weight, and more preferably 10 to 30% by weight, based on the total weight of the non-aqueous electrolyte solution.

The polymerizable compound used in the present invention may be a combination of a monofunctional monomer and a polyfunctional monomer. A combination of a monofunctional monomer and a polyfunctional monomer capable of forming a crosslinked polymer matrix is particularly preferable. Further, when a trifunctional monomer is used as the polyfunctional monomer, a crosslinked polymer matrix having a higher ionic conductivity and having sufficient strength and viscoelasticity as a solid electrolyte for an electrochemical device can be obtained. That is, when the polymer matrix is a cross-linked polymer matrix, the above-mentioned ionic conductivity polymer solid electrolyte having better retention of the electrolytic solution can be obtained, and the reliability and the ionic conductivity are very high, and the solid electrolyte is solid. A polymer solid electrolyte for an electrochemical device having a solid strength sufficient for use as an electrolyte can be obtained, and a secondary battery having a favorable positive electrode / negative electrode interface state can be obtained as an electrochemical device.

(3) Polymerization initiator As the polymerization initiator, carbonyl compounds (benzoins (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, methylbenzoyl formate, etc.), sulfur compounds (diphenyl sulfide, dithiocarbamate, etc.), halogenated polycondensed hydrocarbons ( α-chloromethylnaphthalene, etc.), pigments (acrylic flavin, fluorescein, etc.), metal salts (iron chloride, silver chloride, etc.), onium salts (p-methoxybenzenediazonium) , Hexafluorophosphate, diphenyliodonium,
And a photopolymerization initiator such as triphenylsulfonium). These can be used alone or as a mixture of two or more kinds. Preferred photopolymerization initiators are carbonyl compounds, sulfur compounds and onium salts.

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

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

(4) Properties 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 characteristics and tackiness, and further has excellent liquid retention while containing a large amount of electrolytic solution, and excellent shape retention. The ionic conductivity of the solid electrolyte of the present invention at 25 ° C. according to the AC impedance method is greatly influenced by the conductivity of the non-aqueous electrolyte solution which is a constituent element of the electrolyte, and although it does not exceed it, it may be solidified. Almost no decrease in conductivity, usually 1/10 ⁴ ~
It has 1/10 ² S / cm. Dynamic viscoelasticity tester for solid electrolyte of the present invention [MR-300 Solid Meter Co., Ltd.
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. It does not dissolve even at 100 ° C. Elongation is 20% or more and has a recovery force for stretching deformation without breaking up to about 400% at the maximum. Also,
It does not break even when bent 180 degrees.

The solid electrolyte of the present invention is a creep meter [Yamaden Co., Ltd. RE-3305, plunger cross section 2c].
When the time variation of the strain amount was measured using m ² , load of 30 g], the strain amount does not change with time and has a low creep characteristic. Using a creep meter, load 25g /
Even if the solid electrolyte is compressed in cm ² , the electrolytic solution contained therein does not flow out. Furthermore, this viscoelastic body exhibits high tackiness, and even if the viscoelastic bodies are bonded to each other and then peeled, the material is destroyed and is not peeled from the bonded surface.

Next, the case where the polymer electrolyte of the present invention is used as a battery electrolyte will be described in detail. Generally, a battery is composed of 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 the electrolyte in this battery, an advantageous battery which has never been obtained 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 it makes the electric field between the electrodes uniform and improves the strength. In order to improve the reliability of the obtained battery, it is preferable to be integrated with the diaphragm, and such consideration is necessary especially in the secondary battery. In particular, when the polymerizable compound of the present invention is used, it is easy to integrate the membrane and the solid electrolyte, and the solid electrolyte is directly formed in the battery container having the membrane, or the composition for forming the solid electrolyte is formed in the membrane. The product can be integrated by impregnating the product and conducting 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 structure which does not require integration with a diaphragm. An ion conductive solid electrolyte can be obtained. In addition, the solid electrolyte formed by this formulation is a viscoelastic body by itself, and when forming an electrochemical element such as a battery, it has an ionic conductivity of 1 /
The elastic modulus is 10 ² dyne while being kept above 10 ⁴ S / cm.
/ Cm ² or more. Especially, the ionic conductivity is 1 /
When it is 10 ³ S / cm or more, the elastic modulus is 10 ² to 10 ⁵ dy.
Since it is ne / cm ² , it can also work effectively as an electrochemical element. The polymer solid electrolyte of the present invention can be used as a polymer solid 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 complex oxide; LiMn
O ₂ , LiMn ₂ O ₄ , LiCoO ₂ , LiNiO _2, etc.), a one-dimensional graphitized product which is a thermal polymer of an organic substance, carbon fluoride, graphite or 1/10 ² S.
/ Cm or more conductive polymers, specifically, polyaniline, polypyrrole, polyazulene, polyphenylene, polyacetylene, polyphthalocyanine, poly-3-methylthiophene, polypyridine, polydiphenylbenzidine and the like and these Examples thereof include derivatives, 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 compared to inorganic materials. Further, since the conductive polymer is a plastic in terms of molding and processability, it is possible to take advantage of the characteristics that have not been available in the past. Although the conductive polymer has the above-mentioned advantages, the secondary battery using the conductive polymer as the positive electrode has a low volume energy density due to the low density of the active material, and also has an electrode in the electrolytic solution. The electrolyte is sufficient for the reaction, and the concentration of the electrolyte changes greatly with the charge / discharge reaction.Therefore, the change in liquid resistance is large, and an excessive amount of electrolyte is required for a smooth charge / discharge reaction. There is a problem that becomes. This is a disadvantage in improving the energy density.

On the other hand, it is conceivable to use an inorganic chalcogenide compound or an inorganic oxide for the positive electrode as an active material having a high volume energy density. However, in these, the diffusion rate of cations in the electrode due to the electrode reaction accompanying charging and discharging. There are problems that it is slow, rapid charge / discharge is difficult, reversibility is poor against over-discharge, and cycle life is shortened. Further, 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 that case, the mechanical strength of the electrode is not sufficient. In addition, when the lithium ions are excessively accumulated in the over discharge, the crystal structure is destroyed and the secondary battery cannot function as a secondary battery.

In order to solve the above-mentioned problems, it is possible to use an organic and inorganic composite active material.
In this case, the polymer active materials used are all required to have high electrical conductivity by electrochemical doping, and the electrode materials are required to have electrical conductivity of 1/10 ² S / cm or more. These polymer materials have a high electric conductivity and a current collecting ability, have a binding ability as a polymer, and further function as an active material. In addition, since the conductive polymer is insulated at a base potential, even when this composite positive electrode is in an overdischarged state, the conductive polymer is insulated, so that the inorganic active material contained therein contains more lithium ions than necessary. Is prevented from being accumulated and the crystal structure of the inorganic active material is prevented from being destroyed. As a result, it is possible to construct an electrode that is substantially resistant to overdischarge.

As the conductive polymer used for such a composite electrode, redox active materials such as polyacetylene, polypyrrole, polythiophene, polyaniline and polydiphenylbenzidine can be mentioned, and particularly remarkable effect is obtained in nitrogen-containing compounds. Can be seen. These conductive polymer materials are required to have high ionic conductivity in terms of diffusivity of ions as well as conductivity. Further, the inorganic active material used for the composite positive electrode is preferably one having excellent potential flatness, and specifically, an oxide of a transition metal such as V, Co, Mn, or Ni or a composite oxide of the above transition metal and an alkali metal is used. It can be illustrated.

(2) Positive Electrode Current Collector Examples of the positive electrode current collector used in the present invention include metal sheets such as stainless steel, gold, platinum, nickel, aluminum, molybdenum and titanium, metal foils, metal nets, punching metals. Examples include meshes and nonwoven fabrics made of expanded metal, metal-plated fibers, metal-deposited wires, metal-containing synthetic fibers, and the like. Among them, considering the electrical conductivity, chemical, electrochemical stability, economic efficiency, workability, etc., aluminum,
It is preferable to use stainless steel. Aluminum is more preferable because of its lightness 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 roughening, the contact area of the active material layer is increased, and the adhesion is also improved, which has the effect of lowering the impedance of the battery. Further, in the production of an electrode using a coating solution, it is possible to greatly improve the adhesion between the active material and the current collector by subjecting it to a surface roughening treatment.

The roughening treatment includes polishing with emery paper, blasting treatment, and chemical or electrochemical etching, whereby the current collector can be roughened. Particularly, in the case of stainless steel, etched aluminum is preferable, and in the case of aluminum, etched aluminum is preferable. Since aluminum is a soft metal, the blasting treatment cannot be effectively roughened, and the aluminum itself is deformed. On the other hand, the etching treatment can effectively roughen the surface on a microscopic order without significantly reducing the deformation of aluminum or its strength, and it is possible to roughen aluminum. 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 polymer, and fired body of natural polymer. In the present invention, synthetic polymer such as phenol and polyimide and natural polymer are reduced in an atmosphere of 400 to 800 ° C. Insulating or semiconducting carbon body obtained by firing at, coal, pitch,
Conductive carbon bodies, cokes, pitches, synthetic polymers and natural polymers obtained by firing synthetic polymers or natural polymers in a reducing atmosphere at 800 to 1300 ° C.
Those obtained by firing in a reducing atmosphere at a temperature of 000 ° C. or higher, and graphite-based carbon bodies such as natural graphite are used. Among them, a carbon body obtained by firing mesophase pitch and coke in a reducing atmosphere at 2500 ° C. or higher and natural graphite have excellent potential flatness and favorable electrode characteristics, and a composite of these is also a good electrode as a negative electrode. Have characteristics. The carbon body is formed into a sheet by using a wet papermaking method from the carbon body and a binder, or by a coating method from a coating material in which a suitable binder is mixed with a carbon material. The electrode can be manufactured by supporting the electrode on the current collector by a method such as coating, adhesion, or pressure bonding, if necessary.

[4. Separator] A separator may be used in the battery of the present invention. As the separator, it is preferable to use one that has a low resistance to the movement of ions of the electrolyte solution and is excellent in retaining the solution. Examples of such separators are glass fiber, filters, polyester, Teflon, polyflon, polypropylene,
Examples thereof include non-woven fabric filters made of polymer fibers such as polyethylene, non-woven fabric filters made by mixing glass fibers and these polymer fibers.

The battery of the present invention can be manufactured by using a solid electrolyte composed of the viscoelastic body composed of a high molecular weight polymer and a non-aqueous electrolytic solution instead of the solid electrolyte in the 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 body having high flexibility, on the electrode, on the diaphragm or It is preferably formed by directly carrying out a polymerization reaction in the electrode. That is, battery elements such as electrodes and diaphragms are impregnated with the solid electrolyte-forming composition,
It is preferable that the solid electrolyte and the battery element are integrated by forming a viscoelastic body by a polymerization means such as heating or irradiation with actinic rays. The battery element and the solid electrolyte may be integrated for each battery element, but the combination of the positive electrode and the diaphragm, the combination of the negative electrode and the diaphragm, or the combination of the positive electrode, the diaphragm and the negative electrode may be combined with the solid electrolyte. It may be integrated. In this way, if the battery element and the solid electrolyte are integrated, the electrode reaction on the positive electrode and the negative electrode and the movement of ions can proceed smoothly, and the internal resistance of the battery can be greatly reduced.

[0038]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.
In the following, parts and% indicate parts by weight and% by weight, respectively. In addition, the non-aqueous solvent and the electrolyte salt were sufficiently purified to a water content of 20 ppm or less, and the battery grade deoxidized and denitrified was used.
All operations were performed under an inert gas atmosphere. Further, the ion conductivity is measured by using a SUS cylindrical container (inner diameter 20 mm) whose inner peripheral surface excluding the bottom surface is covered with an insulating tape as a counter electrode.
Was filled with a solid electrolyte and the surface of the solid electrolyte was pressure-bonded with a cylinder made of SUS having a diameter of 18 mm as a working electrode. Measurement is 0 ℃ and 25 ℃
(Cell for measuring ionic conductivity).

Example 1 Ionic Conductive Polymer Solid Electrolyte (I) 2.0 mol / l L dissolved in non-aqueous solvent: ethylene carbonate / diethyl carbonate (2/8: volume ratio)
80.0 parts of electrolyte solution of iPF ₆ solution, 20.0 parts of ethyldiethylene glycol methacrylate as a monomer, 0.05 of benzoin isopropyl ether as a photoinitiator
6 parts were added, mixed and dissolved to prepare a photopolymerizable solution. This solution was placed in a cell for measuring ionic conductivity and irradiated with a high pressure mercury lamp equipped with a cold mirror condensing device to solidify the electrolytic solution. When this ionic conductivity was measured, it was 6.6 × 10 ^-3.
S / cm (25 ° C.), elastic modulus is 1.9 × 10 ³ d
It was yne / cm ² . Further, when the ionic conductivity was measured at 0 ° C., it was 3.0 × 10 ⁻³ S / cm.

Comparative Example 1 An electrolytic solution was solidified in the same manner as in Example 1 except that the nonaqueous solvent: ethylene carbonate / diethyl carbonate (7/3: volume ratio) was used. This ionic 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
It was found to be ⁻³ S / cm ² , and the elastic modulus was excellent, but the ionic conductivity was inferior, and the ionic conductivity was remarkably inferior at low temperatures.

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

Example 2 Ionic Conductive Polymer Solid Electrolyte (II) 1.8 mol / l L dissolved in non-aqueous solvent: ethylene carbonate / dimethyl carbonate (4/6: volume ratio)
iN (CF ₃ SO ₂ ) ₂ solution and 0.2 mol / l Li
80.0 parts of a mixed electrolyte of BF ₄ solution was added with ethoxydiethylene glycol methacrylate 20.0 as a monomer.
Parts, 0.056 parts of bis (4-t-butylcyclohexyl) peroxydicarbonate as a thermal polymerization initiator were added and mixed and dissolved to prepare a thermopolymerizable solution, which was subjected to thermal polymerization at 50 ° C. for 2 hours to prepare an electrolytic solution. Solidified. When the 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 , which was particularly excellent in tackiness. Moreover, the ionic conductivity at 0 ° C. is 2.4 ×
It was 10 ⁻³ S / cm.

Comparative Example 3 An electrolytic solution was solidified in the same manner as in Example 2 except that LiClO ₄ was used instead of the non-aqueous solvent: ethylene carbonate / dimethyl carbonate (8/2: volume ratio) and the sulfonate electrolyte. . This ionic conductivity is 0.9 × 10 ^-3 S /
cm (25 ° C.), 0.4 × 10 ⁻³ S / cm (0 ° C.), and elastic modulus of 6.6 × 10 ³ dyne / cm ² , which is excellent in elastic modulus but brittle and poor in adhesiveness. It was also found that the ionic conductivity was significantly inferior at both 25 ° C and 0 ° C.

Example 3 Ionic Conductive Polymer Solid Electrolyte (III) 2.0 mol / l Li dissolved in non-aqueous solvent: ethylene carbonate / dimethyl carbonate (3/7: volume ratio)
Ethoxy diethylene glycol acrylate 15.8 as a monofunctional monomer in 84.0 parts of electrolyte solution of PF ₆ solution.
Parts, 0.2 parts of trimethylolpropane triacrylate as a polyfunctional monomer, and 0.056 parts of benzoin isopropyl ether as a photoinitiator were added and mixed to prepare a photopolymerizable solution. This solution was placed in a cell for measuring ionic conductivity and irradiated with a high pressure mercury lamp equipped with a cold mirror condensing device to solidify the electrolytic solution. When this ionic conductivity was measured, it was 6.4 × 10 ⁻³ S / cm (25 ° C.), and the elastic modulus was 3.6 × 10 ³ dyne / cm ² . Furthermore, when the ionic conductivity was measured at 0 ° C., it was 2.8 × 10 ^-3.
It was S / cm.

Comparative Example 4 The electrolytic solution was solidified in the same manner as in Example 3 except that the nonaqueous solvent: ethylene carbonate / dimethyl carbonate (6/4: volume ratio) was used. When the ionic conductivity was measured, it was 2.2 × 10 ⁻³ S / cm (25 ° C.), and the elastic modulus was 4.8 × 10 ³ dyne / cm ² . Further 0
Ionic conductivity measured at ℃ 0.8 × 10 ^-3 S
/ Cm, which was excellent in elastic modulus but inferior in ionic conductivity.

Example 4 Ionic 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 ) 86 parts of an electrolytic solution of ₂ solution and 0.2 mol / l LiPF ₆ , 14.0 parts of ethoxydiethylene glycol acrylate as a monofunctional monomer, 0.2 part of trimethylolpropane triacrylate as a polyfunctional monomer, and benzone isopropyl as a photoinitiator. 0.056 parts of ether was mixed and dissolved to prepare a photopolymerizable solution. Hereinafter, the electrolytic solution was solidified in the same manner as in Example 1. This ionic conductivity is 3.6 × 10
^-3 S / cm (25 ° C), elastic modulus 4.0 × 10 ³ dyn
It was e / cm ² and was excellent in tackiness.
Furthermore, the ionic conductivity at 0 ° C. was 2.0 × 10 ⁻³ S / cm.

Comparative Example 5 14.0 parts of ethoxydiethylene glycol acrylate whose monomer is a monofunctional monomer, 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. This 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 Production of Electrochemical Element (I) (Positive Electrode) 3 parts by weight of polyvinylidene fluoride was dissolved in 38 parts by weight of N-methylpyrrolidone to prepare LiCoO 2 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 in the air using a wire bar and dried at 125 ° C. for 30 minutes to prepare an electrode having a film thickness of 60 μm. This is the positive electrode,
The counter electrode was a Li plate, the photopolymerizable solution prepared in Example 3 was permeated, and the high-pressure mercury lamp was irradiated to solidify the electrolytic solution.
A charge / discharge test was conducted. HJ-2 made by Hokuto Denko for charge / discharge test
Using a 01B charge / discharge measuring device, charge with a current of 0.4 mA until the battery voltage reaches 3.7 V, and after a pause for one hour,
With a current of 0.4 mA, the battery voltage is discharged to 2.5 V,
This charging / discharging was repeated thereafter. At this time, the discharge capacity densities at the initial and 50th cycles were 318 mAh / cc and 309 m.
It was Ah / cc. The initial discharge capacity density at 0 ° C was 223 mAh / cc.

Example 6 Preparation of Electrochemical Device (II) (Negative Electrode) 2 parts by weight of polyvinylidene fluoride was dissolved in 58 parts by weight of N-methylpyrrolidone, and 40 parts by weight of coke calcined at 2500 ° C. was added, A roll mill method was used to mix and disperse under an inert atmosphere to prepare a negative electrode coating material. This was applied to 20 μm copper foil in the air using a wire bar, and 10
It was dried at 0 ° C. for 15 minutes to prepare an electrode having a film thickness of 60 μm. Using this as a negative electrode and a counter electrode as a Li plate, the photopolymerizable solution prepared in Example 1 was permeated and irradiated with a high pressure mercury lamp to solidify the electrolytic solution, and a charge / discharge test was conducted. The HJ-201B charge / discharge measuring device manufactured by Hokuto Denko was used for the charge / discharge test, which was a constant current until the voltage became 0 V at a current of 1.5 mA, followed by constant voltage charging for 3 hours, and after 1 hour of rest, 1.5 mA. With current, the battery voltage was discharged to 0.8 V, and this charging / discharging was repeated. 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.
Was / 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 127 mAh / cc. Further, a negative electrode was produced 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 measured and found to be 106 mAh / cc. As described above, the deterioration of the initial discharge capacity was remarkable especially at low temperatures.

Example 7 Production 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 was added to N.
-Crystalline V ₂ O ₅ when dissolved in 50 parts by weight of methylpyrrolidone
50 parts by weight and 6 parts by weight of graphite were added and mixed and dispersed using an homogenizer in an inert atmosphere to prepare a positive electrode coating material. 20μ in the air using a wire bar
It was applied onto a mAl foil and dried at 100 ° C. for 15 minutes to prepare an electrode having a film thickness of 60 μm. (Negative electrode) The negative electrode produced in Example 6 was used. The positive and negative electrodes were impregnated with the photopolymerizable solution prepared in Example 3 and irradiated with a high pressure mercury lamp to solidify the electrolytic solution. These were laminated, the three sides were heat-sealed, and the remaining one side was sealed under reduced pressure while uniformly applying pressure to the power generation element part, to manufacture a battery. In the charge / discharge test, Hokuto Denko HJ-201B charge / discharge measuring device was used to evaluate the battery characteristics in the same manner as in Example 6. At this time, the discharge capacity at the initial and 50th cycles is 1
It was 0.9 mAh and 10.4 mAh. Further, the discharge capacity at 0 ° C. was 7.7 mAh. It was possible to manufacture a battery with little deterioration at low temperatures.

[0052]

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

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-10-294015 (JP, A) JP-A-10-223044 (JP, A) Special Table 2000-504148 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01B 1/06 H01M 10/40 H01M 6/18

Claims (5)

(57) [Claims] 1. A polymer solid electrolyte having a polymer as a matrix, wherein the polymer solid electrolyte has at least the following formula (I): LiXFn (I) (wherein X is B, P, As, Sb). And n is 4 when X is B and is 6 when P, As and Sb) (A1) The following formula (II): LiX (SO ₂ R ₃₎ n (II) wherein, X is n, C, B, O or CR ₄ group _{(R 4} is an alkyl group), _{R 3} is _C 2 _{F 5,} n is 1 to 3
Is an integer. ] The sulfonate (A2) represented by and at least a cyclic carbonate and an acyclic carbonate (B) are contained, and the volume ratio of the cyclic carbonate / acyclic carbonate is less than 1. Ion conductive polymer solid electrolyte. 2. The ion conductive polymer solid electrolyte according to claim 1, wherein the polymer matrix is a crosslinked polymer matrix. 3. An electrochemical element comprising the ion conductive polymer solid electrolyte according to claim 1 or 2 as a constituent element. 4. The electrochemical device according to claim 3, wherein the ion conductive polymer solid electrolyte is formed by being integrated with at least one component of the electrochemical device. 5. The electrochemical device according to claim 3, wherein the electrochemical device is a non-aqueous secondary battery.