JP2001291424A - High polymer solid electrolyte and secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high polymer solid electrolyte having high ionic conductivity and retaining superior electrochemical stability, liquid holding property and high temperature stability, and a secondary battery using the same. SOLUTION: The high polymer solid electrolyte has a high molecular compound containing nitrogen atom, incorporated with a metal salt of a Ia group in a periodic table. Such a high molecular compound is preferably a copolymer consisting of (metha)acrylate containing nitrogen atom such as 2-(dimethylamino) ethyl(metha)acrylate and (metha)acrylate not containing nitrogen atom such as polyether(metha)acrylate and polycarbonate (metha)acrylate. The secondary battery contains the high polymer electrolyte.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a solid polymer electrolyte used for a primary battery, a secondary battery, a capacitor, and the like, and a secondary battery using the same. More specifically, the present invention relates to an acrylate or methacrylate polymer solid electrolyte excellent in high-temperature stability and a secondary battery using the same.

[0002]

2. Description of the Related Art Conventionally, liquid electrolytes have been used for electrochemical devices such as primary batteries, secondary batteries, and capacitors. However, when a liquid electrolyte is used, there is a concern about leakage from a product container, and therefore, there has been a demand for an improvement for improving long-term reliability in using an electrochemical element.

As one improvement method, a method using a solid electrolyte instead of a liquid electrolyte has been studied.
If a solid electrolyte is used, there is no risk of liquid leakage, so that a highly reliable element can be provided, and there is also an advantage that the element itself can be reduced in size and weight.

In recent years, among solid electrolytes, polymer solid electrolytes have attracted attention and have been studied. The polymer solid electrolyte is
Because of its flexibility, it is estimated that it is possible to flexibly cope with a volume change occurring in the ion-electron exchange reaction process between the electrode and the electrolyte. Therefore, expectations for practical use are increasing.

As an example of such a solid polymer electrolyte, a composite of polyethylene oxide having a polyether structure and an alkali metal salt such as a lithium salt is known. JP-A-5-25353 discloses a cross-linked resin and an inorganic salt mainly composed of a polyoxyalkylene diester compound, a polymethoxyoxyalkylene ester compound, and a copolymer of an oxy compound having a double bond. A polymer solid electrolyte as a constituent component is described. Further, JP-A-6-223842 describes a polymer solid electrolyte comprising an organic polymer substance having a carbonate group as a functional group and a metal salt.

On the other hand, Japanese Patent Application Laid-Open No. 1-241764 discloses that a polycarbonate methacrylate resin obtained by polymerizing a methacrylic acid ester of a polycarbonate polyol has excellent properties as a polymer electrolyte material.

In general, since a solid electrolyte has a lower ionic conductivity than a liquid electrolyte, it is difficult to manufacture a battery having excellent charge / discharge characteristics. Therefore, it is necessary to coexist a carbonate compound or the like as a plasticizer in the solid electrolyte. Is being done. In addition, as the amounts of the plasticizer and the alkali metal salt retained in the solid electrolyte are increased, more excellent charge / discharge characteristics are exhibited. However, the solid electrolyte having an ether structure or a carbonate structure described above does not have sufficient amounts of a plasticizer and an alkali metal salt that can be held. In addition, when the solid polymer electrolyte containing these plasticizers is stored at a high temperature of 80 ° C. or higher, it sometimes becomes liquefied, particularly when LiPF ₆ is used as a metal salt. Therefore, in order to realize primary and secondary batteries that have excellent charge / discharge characteristics using a solid electrolyte and operate stably in a high-temperature environment, they have high ionic conductivity and excellent electrochemical stability. In addition, the appearance of a low-cost polymer solid electrolyte which has a large holding amount of a plasticizer and an alkali metal salt, has excellent stability at high temperatures, and is inexpensive is desired.

[0008]

SUMMARY OF THE INVENTION Accordingly, the present invention has a high ionic conductivity and, at the same time, has excellent electrochemical stability, an improved retention of plasticizers and alkali metal salts, and a high temperature. An object is to provide a solid polymer electrolyte having excellent stability. Another object of the present invention is to provide a secondary battery using such a solid polymer electrolyte.

[0009]

That is, the present invention relates to a polymer solid electrolyte comprising a nitrogen atom-containing polymer compound and a metal salt of Group Ia of the Periodic Table. The nitrogen-containing polymer compound is preferably a polymer of a monomer containing an acrylate and / or methacrylate containing a nitrogen atom. Further, the acrylate and / or methacrylate containing a nitrogen atom and a polymer containing a nitrogen atom are preferably used. It is desirable to use a copolymer with acrylate and / or methacrylate which is not used.

The acrylate or methacrylate containing a nitrogen atom is preferably a compound represented by the general formula (1).

Embedded image In the formula (1), A represents a hydrogen atom or a methyl group, and B represents a nitrogen atom-containing group represented by the general formula (2) or (3).

D—N (R ¹ ) (R ² ) (2) In the formula (2), D represents a divalent organic group, and R ¹ and R ² are a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, it may be the same or different and or both combined with each other divalent hydrocarbon group or a -CH ₂ CH ₂ -O —CH ₂ CH ₂ —.

[0012]

Embedded image In the formula (3), G represents a hydrogen atom or a group having 1 to 4 carbon atoms.
Represents an alkyl group.

The acrylates or methacrylates containing no nitrogen atom include polyether polyols, polyester polyols, polycarbonate polyols,
It is preferably an ester compound obtained by reacting part or all of the hydroxyl groups of at least one polyol compound selected from the group consisting of polyester carbonate polyols with acrylic acid or methacrylic acid.

Further, as a metal salt of Group Ia of the Periodic Table as an electrolyte, LiClO ₄ , LiBF ₄ , LiPF ₆ , L
iAsF ₆ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ ,
At least one compound selected from the group consisting of LiC (CF ₃ SO ₂ ) ₃ is preferable, and LiPF ₆ is particularly preferable.

Further, the present invention provides a secondary battery containing the above-mentioned solid polymer electrolyte having high ionic conductivity, high electrochemical stability, high liquid retention and high storage stability at high temperatures. And has excellent charge / discharge characteristics and long-term reliability.

[0016]

DETAILED DESCRIPTION OF THE INVENTION Next, the respective components of the solid polymer electrolyte according to the present invention and a secondary battery using the same will be described. In this specification, acrylate and methacrylate are collectively referred to as (meth) acrylate.

Polymer Compound The polymer containing a nitrogen atom that can be used in the present invention may be any polymer having a chemical structure containing a nitrogen atom in the main chain or side chain of the polymer molecule. Particularly, a polymer having a poly (meth) acrylate as a basic structure and having a nitrogen atom in a main chain or a side chain thereof is preferable.

Preferred examples of the (meth) acrylate containing a nitrogen atom include (meth) acrylate compounds represented by the following general formula (1).

Embedded image

Here, A represents a hydrogen atom or a methyl group. B is a nitrogen atom-containing group represented by the following general formula (2). ^{D-N (R 1) (} R 2) ········· (2)

In the formula (2), D represents a divalent organic group, and R ¹ and R ² represent a hydrogen atom or a carbon atom having 1 to ² carbon atoms.
10 a hydrocarbon group, it may be the same or different and or both combined with each other divalent hydrocarbon group or a _{-CH 2 CH 2 -O-CH 2} CH 2 - in There may be.

D in the above general formula (2) is preferably a divalent organic group containing a part or all of carbon atoms, hydrogen atoms and oxygen atoms, and more preferably has 1 to 1 carbon atoms. 10 chain or cyclic hydrocarbon groups, general formula-(CHR ³ CHR ⁴ O) _n -CHR ³ CHR
⁴ -, and the general formula ^{- (CHR 5 CR 6 R 7} CHR 8 O) m -CHR 5 C
R ⁶ R ⁷ CHR ⁸ — (where R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , and R ⁸ are a hydrogen atom, a methyl group, or an ethyl group, and n and m
Is an integer of 1 to 10), and is preferably any divalent organic group selected from the group consisting of Specifically, an ethyleneoxyethyl group, 1-methylethyleneoxy- (1-
Methyl) ethyl group, 2-methylethyleneoxy- (1-
Methyl) ethyl group, 2-methylethyleneoxy- (2-
Examples thereof include a methyl) ethyl group and a trimethyleneoxypropyl group.

B may be a nitrogen atom-containing group represented by the following general formula (3).

Embedded image In the formula (3), G represents a hydrogen atom or a carbon atom
To 4 alkyl groups, for example, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group,
And a 1-methylpropyl group.

Examples of the nitrogen-containing (meth) acrylate represented by the general formula (1) include 2- (dimethylamino) ethyl (meth) acrylate and 2- (diethylamino) ethyl (meth) acrylate , 2- (di-n-propylamino) ethyl (meth) acrylate, 2
-(Di-propylamino) ethyl (meth) acrylate, 3- (dimethylamino) propyl (meth) acrylate, 1-piperidineethyl (meth) acrylate, 2
-N-morpholinoethyl (meth) acrylate, 2-
(Dimethylamino) ethoxyethyl (meth) acrylate, 2,2,6,6-tetramethylpiperidin-4-yl (meth) acrylate, 1-methyl-2,2,6,6
-Tetramethylpiperidin-4-yl (meth) acrylate and the like.

In the present invention, the high molecular compound containing a nitrogen atom may be a homopolymer of a nitrogen atom-containing (meth) acrylate, or a nitrogen atom-containing (meth) acrylate and a nitrogen atom-containing (meth) acrylate. A copolymer with a (meth) acrylate which is not used may be used, and the latter is particularly desirable.

Examples of (meth) acrylates containing no nitrogen atom include polyethers in which some or all of the hydroxyl groups of polyether polyol, polycarbonate polyol, polyester polyol, or polyester carbonate polyol have been converted to (meth) acrylate esters. Examples include (meth) acrylate, polycarbonate (meth) acrylate, polyester (meth) acrylate, and polyestercarbonate (meth) acrylate. Here, the polyol means an alcohol having 2 or more hydroxyl groups, and the polyether polyol, the polycarbonate polyol, or the polyester polyol has a weight average molecular weight of 200 to 10
Desirable is 0000, preferably 250 to 20,000, more preferably 300 to 10,000. In addition, weight average molecular weight is 500-100,000, or 1,000.
A polyol of 0 to 20,000 can sufficiently achieve the object of the present invention.

The above-mentioned polyether polyol can be obtained by polymerizing an alkylene oxide or adding an alkylene oxide to a polyhydric alcohol. Examples of the alkylene oxide include ethylene oxide, propylene oxide, oxetane, tetrahydrofuran and the like, and these may be used alone or in combination of two or more. As the polyhydric alcohol, the same glycols and polyols as described above can be used. Specific examples of polyether polyols, polyethylene glycol,
Examples thereof include polypropylene glycol and polybutylene glycol.

The above-mentioned polycarbonate polyol compound can be synthesized by polycondensation with a dihydric or higher polyhydric alcohol and a carbonic acid diester or phosgene. Polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, 1,4
-Butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,3-bis (2
-Hydroxyethoxy) benzene, 1,4-bis (2-
(Hydroxyethoxy) benzene, neopentyl glycol, 2-methyl-1,8-octanediol, 1,9-
Nonanediol, 1,4-cyclohexanediol,
Diols such as 1,4-cyclohexanedimethanol,
Also, trimethylolpropane, trimethylolethane,
Pentaerythritol, ditrimethylolpropane, dipentaerythritol, glycerin, polyols such as sorbitol, and a hydroxyl group obtained by adding 1 to 5 equivalents of ethylene oxide, propylene oxide, or other alkylene oxide to the hydroxyl group of these polyols. Alcohols and the like. These polyhydric alcohols may be used alone or in combination of two or more.

As the carbonic acid diester, dimethyl carbonate,
Diethyl carbonate, diisopropyl carbonate, ethylene carbonate, propylene carbonate and the like,
These may be used alone or in combination of two or more.

The above polyester polyol can be synthesized by polycondensation of a hydroxycarboxylic acid or a lactone, or by polycondensation of a polyhydric alcohol and a polycarboxylic acid. Here, hydroxycarboxylic acid or lactone includes hydroxyacetic acid, lactic acid, β
-Propiolactone, β-butyrolactone, γ-butyrolactone, γ-valerolactone, γ-caprolactone,
γ-heptalactone, γ-octalactone, γ-nonalactone, γ-decanolactone, δ-valerolactone, β
-Methyl-δ-valerolactone, δ-hexalactone,
δ-octalactone, δ-decanolactone, δ-nonalactone, ε-caprolactone and the like. In addition, in order to make a terminal functional group into a hydroxyl group, a polyhydroxy compound having 2 to 6 valences is usually added as a polymerization initiator, and polycondensation is performed.

When a polyester polyol is synthesized by polycondensation of a polyhydric alcohol and a polycarboxylic acid, the polyhydric alcohol may be ethylene glycol, 1,2-
Propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,8
-Octanediol, 1,10-decanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, 1,3-bis (2-hydroxyethoxy) benzene, 1,4-bis (2- Hydroxyethoxy) benzene, 1,4-cyclohexanediol, 1,
Glycols such as 4-cyclohexanedimethanol and the like, and polyols such as trimethylolpropane, trimethylolethane, pentaerythritol, ditrimethylolpropane, dipentaerythritol, glycerin, sorbitol and the like can be mentioned.

Examples of the polycarboxylic acid include malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, maleic acid, cyclohexane-1,2-dicarboxylic acid, cyclohexane-1,3-dicarboxylic acid, cyclohexane-1,
Examples thereof include 4-dicarboxylic acid, cis-tetrahydrophthalic acid, phthalic acid, isophthalic acid, and terephthalic acid. Further, a corresponding acid anhydride or dialkyl dicarboxylate may be used in place of the dicarboxylic acid.

The above-mentioned polyester carbonate polyol can be synthesized from the above-mentioned polyester polyol and diester carbonate or phosgene. When using a carbonic acid diester, dimethyl carbonate, diethyl carbonate, diisopropyl carbonate, diphenyl carbonate, ethylene carbonate, propylene carbonate and the like can be exemplified, and these can be used alone or in combination of two or more. Is also good.

When a (meth) acrylate of a high molecular weight polyol is used, the distance between cross-linking points of the polymer to be synthesized becomes longer, so that the ionic conductivity is improved. It is more preferable because it is excellent.

Method for Producing Polymer Compound One of these nitrogen-containing (meth) acrylates
When producing a polymer compound from a species or two or more species,
Alternatively, when a copolymer is produced from one or two or more (meth) acrylates containing a nitrogen atom and (meth) acrylates not containing a nitrogen atom, the polymer has a weight average molecular weight of 10,000 or more. Preferably, there is. In particular, when a gel electrolyte is used, it is important to use a high molecular weight crosslinked polymer having low solubility in a solvent in the electrolytic solution. Its production is normal poly (meth)
It can be performed under almost the same method and conditions as acrylate.

In the polymerization method, a (meth) -containing nitrogen atom is used.
The acrylate is produced by irradiating ultraviolet rays or radiation or heating in the presence of a (meth) acrylate containing no nitrogen atom, if necessary, and another monomer copolymerizable if necessary.

The other copolymerizable monomers include vinyl monomers and vinylidene monomers.
More specifically, vinyl esters, vinyl ethers,
(Meth) acrylates, allyl ethers and allyl esters are preferred. Specific examples include ethyl (meth) acrylate, ethoxyethyl (meth) acrylate, ethoxyethoxyethyl (meth) acrylate, polyethylene glycol (meth) acrylate, allyl alcohol,
Examples include vinyl acetate, styrene, α-methylstyrene, vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, acrylonitrile, vinyl cyanoacetate, allylamine, isopropylacrylamide vinylene carbonate, and maleic anhydride.

In the case of polymerization by an ultraviolet irradiation method, a photosensitizer can be used, and examples of such a photosensitizer include benzophenone, acetophenone, 2,2-dimethoxy-2-phenylacetophenone and the like. .
In the case of polymerization by a heating method, a thermal polymerization initiator can be used, and depending on the polymerization mode, peroxides such as benzoyl peroxide and peroxydicarbonate,
Azo compounds such as 2′-azobisisobutyronitrile,
Nucleophiles such as alkali metals and electrophiles such as Lewis acids can be used alone or in combination.

When a (meth) acrylate containing a nitrogen atom and a (meth) acrylate containing no nitrogen atom are copolymerized, the copolymerization ratio of both monomers is ((meth) acrylate containing a nitrogen atom) / ( When represented by (meth) acrylate containing no nitrogen atom (weight ratio), it is preferably 0.001 to 10, more preferably 0.01 to 1.

When a solvent is used, examples thereof include alcohols such as methanol, ethanol, propanol, butanol and ethylene glycol; halogenated hydrocarbons such as dichloromethane, chloroform and dichloroethane; and aromatic hydrocarbons such as benzene, toluene and xylene. Hydrogens, saturated hydrocarbons such as hexane, heptane, decane and cyclohexane, ethers such as diethyl ether and tetrahydrofuran (THF), ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, dipropyl carbonate and the like Esters such as carbonates, ethyl acetate, propyl acetate, butyl acetate, γ-butyrolactone, δ-valerolactone, and ε-caprolactone It can be. The amount of the solvent used is 0.5 to 20, preferably 1 to 20, based on the total weight of the monomers.
10 times by weight is desirable.

After polymerization, the resulting polymer is in the form of a powder,
It is obtained in the form of a film, gel, etc., and can be used as a solid electrolyte. When the reaction proceeds in the presence of a solvent, a gel is usually formed, but the gel can be used as it is as a material for the polymer electrolyte,
Further, if necessary, the polymer can be used as a film-like or powder-like polymer from which the solvent has been removed by drying.

Polymer Solid Electrolyte The polymer solid electrolyte according to the present invention comprises one or more of the above-mentioned nitrogen-containing (meth) acrylates and, if necessary, a nitrogen-free (meth) acrylate. Irradiating ultraviolet rays or radiation in the presence of one or more of the above, or other copolymerizable monomers,
Alternatively, a metal salt of Group Ia of the Periodic Table is blended in a polymer produced by heating.

The metal salts of Group Ia of the periodic table include compounds such as lithium, sodium, and potassium, and particularly, LiClO ₄ , LiBF ₄ , LiPF ₆ , LiAsF ₆ , L
iCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃
One or more lithium salts selected from the group consisting of SO ₂ ) ₃ are preferred. Further preferred metal salt is LiPF _6. The metal salt concentration in the solid electrolyte is 0.1 to 10 (mo
1 / l).

The production of the solid electrolyte is carried out in advance from one or more (meth) acrylates containing nitrogen atoms and, if necessary, one or more (meth) acrylate compounds containing no nitrogen atoms. Performed by a method of uniformly mixing the produced polymer with a metal salt of Group Ia of the Periodic Table, or a method of uniformly mixing the monomer and the metal salt of Group Ia of the Periodic Table during polymerization and then proceeding with polymerization. be able to. Particularly, the latter method is preferable because a solid electrolyte in which a metal salt is uniformly dispersed in a polymer can be easily obtained.

For example, one or more of (meth) acrylates containing a nitrogen atom, one or more of (meth) acrylate compounds containing no nitrogen atom, and a metal of Group Ia of the periodic table Add salt, and if necessary, solvent, apply the homogeneous mixture on a flat substrate,
Thereafter, polymerization and gelation can be advanced by light irradiation, radiation irradiation, or heating. Thus, a solid electrolyte thin film having a thickness of 0.1 to 1000 μm can be obtained. In addition, when heating, it is desirable to carry out in a temperature range in which the electrolyte salt does not decompose, for example, 30 to 100 ° C, preferably 40 to 90 ° C.

The solid polymer electrolyte according to the present invention may contain a non-aqueous solvent such as a carbonate ester in addition to the above-mentioned polymer compound and a metal salt of Group Ia of the periodic table. . The amount of the non-aqueous solvent is 0 to 5000 parts by weight, preferably 100 to 200 parts by weight, per 100 parts by weight of the polymer compound.
0 parts by weight is desirable. In order to include a non-aqueous solvent in the polymer compound, polymerization may be performed in the presence of a non-aqueous solvent when producing a polymer solid electrolyte, or a method of impregnating the non-aqueous solvent after polymerization. Etc. may be taken.

As the non-aqueous solvent, carbonate esters or lactones can be suitably used. Examples of carbonates include ethylene carbonate, propylene carbonate,
Linear or cyclic carbonates such as dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate and dipropyl carbonate, and examples of lactones include γ-butyrolactone, δ-valerolactone, and ε-caprolactone.

The solid polymer electrolyte according to the present invention is excellent in liquid retention in a state containing a non-aqueous solvent, high in ionic conductivity, and excellent in storage stability at high temperatures. Such a polymer solid electrolyte can be used for, for example, primary batteries, secondary batteries, capacitors, electrochemical devices such as electrochromic display devices, and medical actuators. In particular, this polymer solid electrolyte is suitable for use as a substitute for an organic electrolyte for a lithium ion secondary battery. Further, it can be used as a binder used for dispersing and fixing the powdery electrode material on the current collector.

The secondary battery according to the secondary batteries present invention, a negative electrode including a negative active material,
It is composed of a positive electrode containing a positive electrode active material and the above-mentioned polymer solid electrolyte disposed therebetween.

As the negative electrode active material, lithium metal, a lithium-containing alloy, a material capable of doping and undoping lithium ions, or the like can be used. Such a material capable of doping and undoping lithium ions can be appropriately selected from carbon materials, tin oxide, silicon, titanium oxide, transition metal nitrides, and the like. Among these, a carbon material capable of doping and undoping lithium ions is preferable, and it may be graphite or amorphous carbon. Specific examples include activated carbon, carbon fiber, carbon black, mesocarbon microbeads, and natural graphite.

As the positive electrode active material, MoS ₂ , TiS ₂ ,
Transition metal oxides or sulfides such as MnO ₂ and V ₂ O ₅ , LiCoO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , L
composite oxides composed of lithium and a transition metal such as iNiO ₂ and LiNi _X Co _(1-X) O ₂ , polyaniline, polythiophene, polypyrrole, polyacetylene, polyacene,
Examples include conductive polymer compounds such as dimercaptothiadiazole / polyaniline complex, and disulfide compounds. Among these, a composite oxide composed of lithium and a transition metal is particularly preferable.

When such a solid polymer electrolyte is used in a secondary battery, a battery can be manufactured by forming the solid polymer electrolyte into a film in advance and sandwiching the solid polymer between a positive electrode and a negative electrode. Instead of a film, a polymer solid electrolyte formed in a gel in advance can be arranged. Further, in a battery manufacturing process including a step of forming a three-layer structure of a positive electrode, a separator, and a negative electrode and then impregnating the same with an electrolytic solution, a polymer compound, a metal of Group Ia of the periodic table is used instead of the electrolytic solution. It is also possible to adopt a method of adding and impregnating a solution comprising a salt and a non-aqueous solvent, followed by gelation. In any case, by using the above-described solid polymer electrolyte according to the present invention, it is possible to manufacture a secondary battery while minimizing the modification of the conventional battery manufacturing process. The shape of the battery may be any shape such as a film type, a coin type, a cylindrical type, or a square type.

[0052]

Next, the present invention will be described through examples.
The present invention is not limited by these examples.

(Synthesis Example 1) 509.4 g (4.8 mol) of diethylene glycol and 509.4 g of 1,4-butanediol were placed in a two-liter three-necked flask equipped with a stirrer, a thermometer, a rectification tower and the like. 5.65 mol), 2.02 g (11 mmol) of a 28% solution of sodium methoxide in methanol and 1035.7 g (11.5 g) of dimethyl carbonate.
Mol), the bath temperature was maintained at 95 ° C for 2 hours, and then the temperature was raised to 155 ° C over 5 hours. At this time, methanol generated by the transesterification was distilled off as an azeotropic composition of dimethyl carbonate (780 g).

Next, the rectification column was removed and the bath temperature was set to 155 ° C.
And gradually reduce the pressure to 0.7 kPa (5 m
The pressure was reduced to mHg), and diethylene glycol and unreacted 1,4-butanediol formed during the polymerization reaction were distilled off over 8 hours in this state (207 g). The mixture was cooled to 80 ° C., and 256 g of toluene was added and stirred. The toluene solution of the intermediate polycarbonate was converted into a turbid colorless viscous oily product, and the yield was 1206.
g (polycarbonate content 79% by weight).

(Synthesis Example 2) 89 g of a polycarbonate toluene solution (70 g in terms of polycarbonate, about 81 mmol of OH groups) and 51 g of toluene were placed in a 300 ml three-necked flask equipped with a stirrer, a thermometer, a distillation tower and a blowing tube. , 4-methoxyphenol 0.14 g (200
0 ppm), 0.7 g (7 mmol) of concentrated sulfuric acid and 7.3 g (101 mmol) of acrylic acid. The temperature of the bath was gradually increased to 130 ° C. with stirring. The azeotrope of water and toluene generated with the progress of the esterification reaction is refluxed, and the generated water is separated. When water generation is completed (about 1.65 ml) in about 5 hours, the bath temperature is raised to 80%. After the temperature was lowered to ° C., 1.24 g (12 mmol) of acetic anhydride was added and stirred for 3 hours. By this operation, unreacted terminal hydroxyl groups were acetylated.

Next, the bath temperature was lowered to 40 ° C., and Kyowaad 200, a solid base product of Kyowa Chemical Industry Co., Ltd., was used.
0g was added and stirred for 1 hour to neutralize sulfuric acid, acrylic acid and acetic acid. Then, it cooled to room temperature and left still overnight. On the other hand, a filter paper was set on a Kiriyama funnel, about 10 g of celite was spread thereon, and the celite was washed with 30 ml of methanol and 30 ml of toluene sequentially. Next, the reaction mixture was subjected to suction filtration, and the insolubles were washed with 30 ml of toluene. The filtrate was concentrated at 35 ° C. under reduced pressure while blowing a small amount of dry air into the filtrate. 35 g of diethyl carbonate was added to the obtained pale yellow viscous oil, and stirring was continued at 35 ° C. until the solution became homogeneous. By concentrating and drying at 30 ° C. or less while blowing a small amount of dry air under reduced pressure, polycarbonate acrylate was obtained as a pale yellow viscous oil. The yield was 76.5 g, and Mw was 4,300 (polystyrene conversion value).

(Synthesis Example 3) Adipic acid 26 was placed in a glass reaction vessel equipped with a stirrer, thermometer and Liebig condenser.
3 g, 212 g of diethylene glycol and 3.6 mg of titanium tetrabutoxide.
The temperature was gradually raised to 0 ° C., and the reaction was continued for 24 hours while removing generated water outside the reaction system. As a result, the desired polyester diol was obtained as a colorless oily substance in a yield of 310.
g.

(Synthesis Example 4) The polyester diol obtained in Synthesis Example 3 (OH value: 49 mgKOH / g) was placed in a glass reaction vessel equipped with a stirrer, a thermometer, and a Dean Stark.
46.8 g, acrylic acid 2.97 g, p-toluenesulfonic acid monohydrate 0.94 g, 4-methoxyphenol 0.047 g and toluene 47 ml were charged. The generated water was removed from the reaction system while heating and refluxing for 5 hours. After the temperature was lowered to 80 ° C., 1.05 g of acetic anhydride was added, and stirring was further continued at this temperature for 1 hour. Then, after lowering to 60 ° C., 0.20 g of methanol was added,
Stirring was continued at this temperature for 1 hour. After that, the temperature is raised to 40 ° C.
Then, 7.0 g of magnesium oxide was added, and stirring was continued at this temperature for 1 hour. After cooling to room temperature, the insolubles were filtered, and the filtrate was concentrated under reduced pressure to obtain 49.1 g of the target polyester acrylate as a colorless oil having Mw of 3700.

Example 1 2-dimethylaminoethyl acrylate was used as an acrylate containing a nitrogen atom.
Diacrylate of polycarbonate diol synthesized in Synthesis Example 2 was used as an acrylate containing no nitrogen atom. As an electrolyte, LiPF ₆ was added to an equal mixture (volume ratio) of ethylene carbonate and diethyl carbonate.
(Mol / l). Each was mixed in the weight ratio shown in Table 1, and AIBN was added to this solution at 1000 pp.
m.

Thereafter, 2.4 g of the solution was placed in a sample bottle and heated at 80 ° C. for 1 hour. After cooling the polymer electrolyte thus obtained to room temperature, the weight (excluded electrolyte: g) of the liquid separated on the upper portion of the gel was measured (liquid retention test), and the liquid retention was determined from the following formula. The results were calculated and the results are shown in Table 1. Liquid retention (%) = {1- (amount of excluded electrolyte / 2.4)} × 1
The polymer electrolyte was stored under nitrogen at 80 ° C. for 4 days (storage test). During this period, the number of days until the start of liquefaction of the gel was measured, and the results are shown in Table 1.

(Example 2) In Example 1, a product (LA-82) manufactured by Asahi Denka Co., Ltd. represented by the following formula (4) was used as the acrylate containing a nitrogen atom. Each monomer composition was changed to three types as described in Table 1 (Example 2
1-2) Others were performed in the same manner as in Example 1 to obtain a polymer electrolyte. A liquid retention test and a storage test at 80 ° C. were performed on the polymer electrolyte, and the results are shown in Table 1.
Are also shown.

[0062]

Embedded image

Example 3 In Example 1, the above-mentioned product (LA-82) manufactured by Asahi Denka Co., Ltd. was used as the acrylate containing a nitrogen atom. The described polyester diol diacrylate was used. The composition of each monomer was changed to three types as described in Table 1 (Example 3
1-3-3), and the other steps were performed in the same manner as in Example 1 to obtain a polymer electrolyte. A liquid retention test and a storage test at 80 ° C. were performed on the polymer electrolyte, and the results are shown in Table 1.

(Comparative Example 1) In Example 1, without using a (meth) acrylate containing a nitrogen atom, a mixture of diacrylate of polycarbonate diol and an equal mixture of ethylene carbonate and diethyl carbonate (volume ratio) as an electrolyte was used. A solution in which LiPF ₆ was dissolved at a concentration of 1 (mol / l) was used. Each was mixed at the weight ratio shown in Table 1, and then a liquid retention test and a storage test at 80 ° C. were carried out in the same manner as in Example 1. The results are also shown in Table 1.

(Comparative Example 2) In Example 3, without using a acrylate containing a nitrogen atom, an equal mixture (volume ratio) of diacrylate of polyester diol and ethylene carbonate and diethyl carbonate as an electrolyte was used.
And a solution in which LiPF ₆ was dissolved at a concentration of 1 (mol / l). Each was mixed at the weight ratio shown in Table 1, and then a liquid retention test and a storage test at 80 ° C. were carried out in the same manner as in Example 1. The results are also shown in Table 1.

[0066]

[Table 1]

Example 4 A polymer electrolyte was prepared using the monomers described in Example 3, and a button-type battery containing the polymer electrolyte was prepared. The battery characteristics were evaluated.

<Preparation of Gel Type Polymer Electrolyte> First, polyester diol synthesized in Synthesis Example 4 as an acrylate containing no nitrogen atom, using a product (LA-82) manufactured by Asahi Denka Co., Ltd. as an acrylate containing a nitrogen atom. (Mw = 3700), and mixed at a ratio of 5:95 (weight ratio) to prepare a monomer solution.

Next, ethylene carbonate (EC) and diethyl carbonate (DEC) were converted into EC: DEC = 5.
The mixture was mixed at a ratio of 8:42 (weight ratio) to obtain a non-aqueous solvent, LiPF ₆ as an electrolyte was dissolved in the non-aqueous solvent, and the non-aqueous electrolyte was adjusted so that the electrolyte concentration became 1.0 (mol / l). A liquid was prepared.

The above monomer solution and nonaqueous electrolyte were
After mixing at a ratio of 8 (weight ratio), the polymerization initiator A
IBN was added to a concentration of 1000 ppm with respect to the monomer solution to prepare a monomer electrolyte solution. continue,
100 μl of the above-mentioned monomer electrolyte solution was impregnated into a 200 μm-thick nonwoven fabric punched into a disk having a diameter of 19 mm, and heated at 60 ° C. for 2 hours to obtain a gel-type polymer electrolyte.

<Preparation of Negative Electrode> Mesocarbon microbeads manufactured by Osaka Gas Co., Ltd. (trade names: MCMB6-28, d
002 = 0.337 nm, density 2.17 g / cm ³ ) 90 parts by weight of carbon powder and 10 parts by weight of polyvinylidene fluoride (PVDF) as a binder were mixed, and N-
The paste was dispersed in methylpyrrolidone to prepare a paste-like negative electrode mixture slurry. Next, this negative electrode mixture slurry was applied to a negative electrode current collector made of a 20-μm-thick strip-shaped copper foil, and dried to obtain a strip-shaped carbon negative electrode. The thickness of the negative electrode mixture after drying is 2
It was 5 μm. Furthermore, this strip electrode is 15 mm in diameter.
, And compression molded to form a negative electrode.

<Preparation of Positive Electrode> L manufactured by Honjo Chemical Co., Ltd.
iCoO ₂ (product name: HLC-21, average particle size 8 μm)
91 parts by weight of fine particles, 6 parts by weight of graphite as a conductive material, and polyvinylidene fluoride (PVD) as a binder
F) was mixed with 3 parts by weight to prepare a positive electrode mixture, and dispersed in N-methylpyrrolidone to obtain a positive electrode mixture slurry. This slurry was applied to a 20-μm-thick aluminum foil positive electrode current collector, dried, and compression-molded to obtain a belt-shaped positive electrode. The thickness of the positive electrode mixture after drying was 40 μm.
Thereafter, the strip-shaped electrode was punched into a disk having a diameter of 15 mm to obtain a positive electrode.

<Preparation of Battery> The disk-shaped gel polymer electrolyte, disk-shaped negative electrode and disk-shaped positive electrode thus obtained were prepared as an electrolyte, a negative electrode and a positive electrode. Each of the negative electrode, the gel-type polymer electrolyte, and the positive electrode was laminated in the order of a stainless steel 2032-size battery can. Thereafter, a stainless steel plate (thickness: 2.4 mm, diameter: 15.4) was placed in the battery can.
mm), and the battery can (lid) was caulked via a polypropylene gasket. As a result, a button-type gel-type polymer electrolyte secondary battery having a diameter of 20 mm and a height of 3.2 mm which can maintain the airtightness in the battery was obtained.

<Measurement of Discharge Capacity> The discharge capacity of the thus obtained gel polymer electrolyte secondary battery was measured at room temperature. In this example, the negative electrode was Li
^The current direction in which ⁺ is doped is defined as charging, and the current direction in which undoping is performed is defined as discharging. The charging was performed by a 4.2 V, 1 mA constant current, constant voltage charging method, and was terminated when the charging current became 50 μA or less. Discharge was performed at a constant current of 1 mA up to 2.75 V. As a result of repeating the above-mentioned charge and discharge for 10 cycles, the charge and discharge efficiency at the 10th cycle was 97%,
The discharge capacity was 120 (mAh /
g).

[0075]

The polymer solid electrolyte according to the present invention has high ionic conductivity, is also excellent in electrochemical stability, and has improved plasticizer and alkali metal salt retention performance. The film-like material is flexible, and the gel-like material has excellent liquid retention and high-temperature stability.

Therefore, the polymer solid electrolyte can be suitably used for primary batteries, secondary batteries, capacitors, electrochemical devices such as electrochromic display devices, medical actuators, and the like.

In particular, a secondary battery containing this polymer solid electrolyte has excellent battery performance such as charge / discharge characteristics and good liquid retention, so that there is almost no fear of liquid leakage from the battery.
It has excellent storage stability at high temperatures and has improved battery reliability.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme court ゛ (Reference) C08K 3/32 C08K 3/32 3/38 3/38 5/41 5/41 5/42 5/42 C08L 33/14 C08L 33/14 55/00 55/00 101/02 101/02 H01G 9/025 H01M 10/40 B 9/035 H01G 9/00 301G 9/028 9/02 311 H01M 10/40 331G (72 Inventor: Shinobu Aoki 580-32, Takuji, Nagaura, Sodegaura-shi, Chiba Mitsui Chemicals, Inc. (72) Inventor: Masahiro Torii 72) Inventor Nobu Enobu 580-32, Takuji Nagaura, Sodegaura City, Chiba Prefecture F-term (reference) 4F070 AA32 AA47 AA50 AA52 AE08 HA02 HA04 HB03 4J002 BG071 BQ001 DD036 DE186 DH006 DK006 EV256 GQ00 4J027 AB AB17 AB18 AB28 AC02 AC03 AC04 AC07 BA07 BA13 BA19 BA24 5G301 CA08 CA16 CA30 CD01 5H029 AJ02 AK03 AL01 AL02 AL06 AL11 AL12 AM16 EJ14 HJ02

Claims (13)

[Claims] 1. A solid polymer electrolyte comprising a nitrogen atom-containing polymer compound and a metal salt of Group Ia of the Periodic Table. 2. The polymer solid electrolyte according to claim 1, wherein said polymer compound containing a nitrogen atom is a polymer of a monomer containing an acrylate and / or methacrylate containing a nitrogen atom. . 3. The nitrogen-containing polymer compound is a copolymer of a nitrogen-containing acrylate and / or methacrylate and a nitrogen-free acrylate and / or methacrylate. The polymer solid electrolyte according to claim 1. 4. The polymer solid electrolyte according to claim 2, wherein the nitrogen-containing acrylate or methacrylate is a compound represented by the general formula (1). Embedded image (In the formula (1), A represents a hydrogen atom or a methyl group, and B represents a nitrogen atom-containing group represented by the general formula (2) or (3).) DN (R ¹ ) (R ² ) (2) (In the formula (2), D represents a divalent organic group, and R ¹
And R ² are a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, which may be the same or different, or both bonded to each other to form a divalent hydrocarbon group or —CH 2 ₂ CH ₂ —O—CH ₂ CH ₂ —) (In the formula (3), G represents a hydrogen atom or a group having 1 to 1 carbon atoms.
4 represents an alkyl group) 5. In the above formula (2), D is a hydrocarbon group having 1 to 10 carbon atoms, and the formula is-(CHR ³ CHR ⁴ O) _n -CHR ³ CHR.
⁴ -, and the general formula ^{- (CHR 5 CR 6 R 7} CHR 8 O) m -CHR 5 C
R ⁶ R ⁷ CHR ⁸ — (where R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , and R ⁸ are a hydrogen atom, a methyl group, or an ethyl group, and n and m
Is an integer of 1 to 10), and is any divalent organic group selected from the group consisting of:
3. The polymer solid electrolyte according to item 1. 6. The acrylate or methacrylate containing a nitrogen atom is 2- (dimethylamino) ethyl (meth) acrylate, 2- (diethylamino) ethyl (meth) acrylate, 2- (di-n-propylamino)
Ethyl (meth) acrylate, 2- (dii-propylamino) ethyl (meth) acrylate, 3- (dimethylamino) propyl (meth) acrylate, 1-piperidineethyl (meth) acrylate, 2-N-morpholinoethyl ( (Meth) acrylate, 2,2,6,6-tetramethylpiperidin-4-yl (meth) acrylate, and 1-methyl-2,2,6,6-tetramethylpiperidin-4-yl (meth) acrylate 3. A compound selected from the group consisting of:
The solid polymer electrolyte according to any one of (1) to (5), wherein
(Meth) acrylate refers to acrylate or methacrylate). 7. The acrylate or methacrylate containing no nitrogen atom is a polyether polyol, a polyester polyol, a polycarbonate polyol,
And an ester compound obtained by reacting a part or all of the hydroxyl groups of at least one polyol compound selected from the group consisting of polyester carbonate polyol and acrylic acid or methacrylic acid. 7. The solid polymer electrolyte according to any one of 6. 8. The solid polymer electrolyte according to claim 7, wherein the polyol compound has a weight average molecular weight of 200 to 100,000. 9. The metal salt of Group Ia of the periodic table is LiC
10 ₄ , LiBF ₄ , LiPF ₆ , LiAsF ₆ , LiCF
₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ S
O ₂₎ polymer solid electrolyte according to claim 1, characterized in that at least one compound selected from the group consisting of _3. 10. The metal salt of Group Ia of the periodic table, wherein the metal salt is Li
The polymer solid electrolyte according to claim 1, characterized in that a PF _6. 11. The polymer solid electrolyte according to claim 1, wherein said polymer compound is a gel-like material holding a non-aqueous solvent. 12. A secondary battery comprising the polymer solid electrolyte according to claim 1. 13. A polymer solid electrolyte according to claim 1, wherein the negative electrode active material is metallic lithium, a lithium-containing alloy, a carbon material capable of doping and undoping lithium ions, and a lithium ion doping. Negative electrode and positive electrode active material containing at least one selected from the group consisting of tin oxide capable of undoping, silicon capable of doping and undoping lithium ions, and titanium oxide capable of doping and undoping lithium ions A secondary battery comprising a positive electrode containing a composite oxide of lithium and a transition metal.