JP2003272708A - Polymer electrolyte and secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polymer electrolyte with high ionic conductivity and high stability in quality, and to provide a secondary battery with a high performance and high stability. <P>SOLUTION: This polymer electrolyte 3 contains polyimide, oligomer, an electrolyte salt, and a nonaqueous solvent, and preferably, the oligomer has at least a repeating unit represented by genera formula -(C<SB>x</SB>H<SB>2x</SB>-O)<SB>m</SB>-, a repeating unit represented by -[CH(R<SP>1</SP>)-CH<SB>2</SB>-O]<SB>n</SB>, (in each repeating unit, x is an integer of 1-6; m and n are m≥0, n≥0, m+n≥5; R<SP>1</SP>is a 1-6C alkyl or benzyl), and comprises at least a positive electrode 1, a negative electrode 2, and the polymer electrolyte 3. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polymer electrolyte and a secondary battery. More specifically, it can be used in electrochemical devices such as batteries and capacitors, is easy to manufacture,
The present invention also relates to a polymer electrolyte having stable quality and a secondary battery using the polymer electrolyte as a constituent element.

[0002]

2. Description of the Related Art Organic electrolyte secondary batteries, typified by lithium ion secondary batteries, have high capacity, high voltage, and high energy. Therefore, great expectations are placed on their development.

In this organic electrolyte secondary battery, lithium or a lithium alloy has been used as a negative electrode active material. When these negative electrode active materials are used, a high capacity can be expected, but dendrite growth of lithium during charging is expected. Due to this, an internal short circuit is likely to occur, which causes a problem that battery performance is deteriorated and safety is poor.

Therefore, it has been proposed to use a carbon material, such as activated carbon or graphite, which can be doped or dedoped with lithium ions as a negative electrode active material, instead of lithium or a lithium alloy, and which has already been put into practical use.

[0005]

In the above-mentioned organic electrolytic solution secondary battery, since the organic solvent is used as the constituent solvent of the electrolytic solution, it is required that the risk of ignition / ignition is small. That is, recently, secondary batteries are often exposed to high temperatures due to changes in the operating environment, but with organic solvents, the vapor pressure of the electrolyte in the batteries is high when the batteries are exposed to high temperatures. There is a risk that the electrolyte that has reached the flash point will come into contact with the outside air due to the operation of the cleavage vent, causing ignition / ignition, and that the internal temperature of the battery will rise due to an internal short circuit, which will cause ignition / ignition. Risk of ignition.

Therefore, in order to improve the safety of the above-mentioned lithium ion secondary battery or lithium metal secondary battery, it has been proposed to use a gel polymer electrolyte having low fluidity or no fluidity. A so-called polymer battery using a polymer electrolyte has been commercialized.
Polymer electrolytes have a lower ionic conductivity than electrolytic solutions, so attempts have been made to improve the ionic conductivity by making a gel electrolyte by impregnating a polymer with an electrolytic solution, but still satisfactory. Polymer batteries that can be produced have not been commercialized. This is because it was not possible to manufacture a polymer electrolyte having a uniform success in commercialization of a polymer battery, high conductivity, and high discharge characteristics.

That is, conventionally, in the production of a polymer electrolyte, polyethylene oxide, polyvinylidene fluoride, a gelling component for gelling an electrolytic solution,
Polymers such as polyacrylonitrile and polymethylmethacrylate have been used, and monomers that are polymerized by heating with a radical initiator and monomers that are polymerized by UV irradiation have been used.

However, polyethylene oxide,
When a polymer such as polyvinylidene fluoride, polyacrylonitrile, or polymethylmethacrylate is used, it must be heated for gelation of the electrolytic solution, which causes decomposition of electrolyte salts such as LiPF ₆ and LiCF ₃ SO ₃ . In addition, there is a problem that workability is poor because of high viscosity.

Further, when a monomer is polymerized using a radical initiator, heating is usually required, and it takes time to complete the reaction, and in addition, oxygen deactivates radicals. There is a problem that it is not possible to react, when polymerizing the monomer by ultraviolet irradiation, it is possible to polymerize at room temperature, but it is difficult to produce a polymer having stable performance in dry air because radicals are generated, and However, since the monomer is mainly polyfunctional, there is a problem that the polymer produced is brittle.

In order to solve the above-mentioned problems of the prior art, the present invention has a high ionic conductivity and excellent quality stability, and can be gelled by being dissolved in room temperature and dry air only to be manufactured. An object of the present invention is to provide a secondary battery with high performance and high safety by easily producing a polymer electrolyte and using the polymer electrolyte.

[0011]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a polymer electrolyte having excellent ion conductivity can be obtained by using a polymer component composed of a polyamide and an oligomer having a specific structure. Heading
The present invention has been completed.

That is, the present invention is as follows: A polymer electrolyte comprising a polyamide having a repeating unit represented by the general formula (1), an oligomer, an electrolyte salt and a non-aqueous solvent,

[Chemical 6] (However, L and M in the formula are L> 0, M ≧ 0, 2 ≦ L
+ M ≦ 1000, and an integer that satisfies 0.05 ≦ L / (L + M) ≦ 1. X is a tetravalent group represented by the formula (2), Y is a divalent group represented by the formula (3), and Z is a formula (4).
The groups selected from the divalent groups represented by are shown below. )

[Chemical 7]

[Chemical 8]

[Chemical 9] (However, in the formulas (2) and (4), X ₁ represents a group selected from the divalent groups represented by the formula (5). Further, the formula (2), the formula (3), The hydrogen atom on the benzene ring in the groups represented by formula (4) and formula (5) is a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, a fluorine atom, and It may be substituted with at least one group selected from trifluoromethyl groups.)

[Chemical 10] 2. The oligomer has at least the general formula — (C _x H _2x
-O) _m- and a repeating unit represented by-[CH (R ¹ )
A repeating unit represented by —CH ₂ —O] _n — (in each repeating unit, x is an integer of 1 to 6, and m and n are
m ≧ 0, n ≧ 0, m + n ≧ 5, and R ¹ has a carbon number of 1 to
2. The polymer electrolyte according to claim 1, which has an alkyl group of 6 or a benzyl group). There is provided a secondary battery comprising at least a positive electrode, a negative electrode, and the polymer electrolyte according to the first or second aspect.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the polyamide which is an essential component comprises at least one bisaminophenol compound having any one of tetravalent groups represented by the formula (2), At least one dicarboxylic acid having a biphenylene skeleton having any one of the divalent groups represented by (3) is used, or as a dicarboxylic acid, represented by the dicarboxylic acid and the formula (4). In combination with a dicarboxylic acid having any of the two groups described above, the conventional acid chloride method, activated ester method, condensation reaction in the presence of a dehydration condensation agent such as polyphosphoric acid or dicyclohexylcarbodiimide, etc. It can be obtained by the method. Further, by combining the polyamide having this biphenylene skeleton with another polyamide which has been conventionally used and which does not undergo a crosslinking reaction, and by forming an interpenetrating network structure, it is possible to obtain a resin having a high heat resistance as well. It is possible. In this case, the polyamide having no biphenylene skeleton includes at least one bisaminophenol compound having any one of the tetravalent groups represented by the formula (2),
It can be obtained by a similar method using at least one dicarboxylic acid having any of the divalent groups represented by the formula (4).

The bisaminophenol compound having a tetravalent group represented by the formula (2) used in the present invention is 2,
4-diaminoresorcinol, 4,6-diaminoresorcinol, 2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane, 2,2-bis (4
-Amino-3-hydroxyphenyl) hexafluoropropane, 2,2-bis (3-amino-4-hydroxyphenyl) propane, 2,2-bis (4-amino-3-hydroxyphenyl) propane, 3,3 ' -Diamino-4,
4'-dihydroxydiphenyl sulfone, 4,4'-diamino-3,3'-dihydroxydiphenyl sulfone, 3,
3'-diamino-4,4'-dihydroxybiphenyl, 4,
4'-diamino-3,3'-dihydroxybiphenyl, 9,
9-bis (4-((4-amino-3-hydroxy) phenoxy) phenyl) fluorene, 9,9-bis (4-
((3-Amino-4-hydroxy) phenoxy) phenyl) fluorene, 9,9-bis ((4-amino-3-hydroxy) phenyl)) fluorene, 9,9-bis ((3-amino-4-hydroxy) ) Phenyl)) Fluorene, 3,3'-diamino-4,4'-dihydroxydiphenyl ether, 4,4'-diamino-3,3'-dihydroxyphenyl ether, 2,2-bis (3-amino-4-)
Hydroxy-2-trifluoromethylphenyl) propane, 2,2-bis (4-amino-3-hydroxy-2-)
Trifluoromethylphenyl) propane, 2,2-bis (3-amino-4-hydroxy-5-trifluoromethylphenyl) propane, 2,2-bis (4-amino-3)
-Hydroxy-5-trifluoromethylphenyl) propane, 2,2-bis (3-amino-4-hydroxy-6)
-Trifluoromethylphenyl) propane, 2,2-bis (4-amino-3-hydroxy-6-trifluoromethylphenyl) propane, 2,2-bis (3-amino-
4-hydroxy-2-trifluoromethylphenyl) hexafluoropropane, 2,2-bis (4-amino-3)
-Hydroxy-2-trifluoromethylphenyl) hexafluoropropane, 2,2-bis (3-amino-4-)
Hydroxy-5-trifluoromethylphenyl) hexafluoropropane, 2,2-bis (4-amino-3-hydroxy-5-trifluoromethylphenyl) hexafluoropropane, 2,2-bis (3-amino-4- Hydroxy-6-trifluoromethylphenyl) hexafluoropropane, 2,2-bis (4-amino-3-hydroxy-6-trifluoromethylphenyl) hexafluoropropane, 3,3'-diamino-4,4'- Dihydroxy-2,2'-bis (trifluoromethyl) biphenyl,
4,4'-diamino-3,3'-dihydroxy-2,2'-bis (trifluoromethyl) biphenyl, 3,3'-diamino-4,4'-dihydroxy-5,5'-bis (trifluoro Methyl) biphenyl, 4,4'-diamino-3,3'-dihydroxy-5,5'-bis (trifluoromethyl) biphenyl, 3,3'-diamino-4,4'-dihydroxy-
6,6'-bis (trifluoromethyl) biphenyl, 4,
4'-diamino-3,3'-dihydroxy-6,6'-bis (trifluoromethyl) biphenyl and the like can be mentioned. These may be used alone or in combination of two or more.

Examples of the dicarboxylic acid having a biphenylene skeleton having a divalent group represented by the formula (3) used in the present invention include 1,2-biphenylenedicarboxylic acid and 1,3-
Biphenylenedicarboxylic acid, 1,4-biphenylenedicarboxylic acid, 1,5-biphenylenedicarboxylic acid, 1,6-
Biphenylenedicarboxylic acid, 1,7-biphenylenedicarboxylic acid, 1,8-biphenylenedicarboxylic acid, 2,3-
Examples thereof include biphenylenedicarboxylic acid, 2,6-biphenylenedicarboxylic acid, and 2,7-biphenylenedicarboxylic acid. From the performance of the obtained polyamide, 2,6-biphenylenedicarboxylic acid and 2,7-biphenylenedicarboxylic acid are particularly preferable. . These may be used alone or in combination of two or more.

Examples of the dicarboxylic acid having a divalent group represented by the formula (4) used in the present invention include isophthalic acid, terephthalic acid, 4,4'-biphenyldicarboxylic acid,
3,4'-biphenyldicarboxylic acid, 3,3'-biphenyldicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 2,3
-Naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-sulfonylbisbenzoic acid, 3,4'-sulfonylbisbenzoic acid, 3,3'-sulfonylbisbenzoic acid, 4,4'-oxybisbenzoic acid Acid, 3,4'-oxybisbenzoic acid, 3,3'-oxybisbenzoic acid, 2,2-bis (4-carboxyphenyl) propane, 2,2-bis (3-carboxyphenyl) propane, 2,2- Bis (4-carboxyphenyl) hexafluoropropane,
2,2-bis (3-carboxyphenyl) hexafluoropropane, 2,2'-dimethyl-4,4'-biphenyldicarboxylic acid, 3,3'-dimethyl-4,4'-biphenyldicarboxylic acid, 2,2 '-Dimethyl-3,3'-biphenyldicarboxylic acid, 2,2'-bis (trifluoromethyl)-
4,4'-biphenyldicarboxylic acid, 3,3'-bis (trifluoromethyl) -4,4'-biphenyldicarboxylic acid,
2,2'-bis (trifluoromethyl) -3,3'-biphenyldicarboxylic acid, 9,9-bis (4- (4-carboxyphenoxy) phenyl) fluorene, 9,9-bis (4- (3- Carboxyphenoxy) phenyl) fluorene, 4,4'-bis (4-carboxyphenoxy) biphenyl, 4,4'-bis (3-carboxyphenoxy) biphenyl, 3,4'-bis (4-carboxyphenoxy) biphenyl, 3 , 4'-bis (3-carboxyphenoxy) biphenyl, 3,3'-bis (4-carboxyphenoxy) biphenyl, 3,3'-bis (3-carboxyphenoxy) biphenyl, 4,4'-bis (4
-Carboxyphenoxy) -p-terphenyl, 4,
4'-bis (4-carboxyphenoxy) -m-terphenyl, 3,4'-bis (4-carboxyphenoxy)
-P-terphenyl, 3,3'-bis (4-carboxyphenoxy) -p-terphenyl, 3,4'-bis (4
-Carboxyphenoxy) -m-terphenyl, 3,
3'-bis (4-carboxyphenoxy) -m-terphenyl, 4,4'-bis (3-carboxyphenoxy)
-P-terphenyl, 4,4'-bis (3-carboxyphenoxy) -m-terphenyl, 3,4'-bis (3
-Carboxyphenoxy) -p-terphenyl, 3,
3'-bis (3-carboxyphenoxy) -p-terphenyl, 3,4'-bis (3-carboxyphenoxy)
-M-terphenyl, 3,3'-bis (3-carboxyphenoxy) -m-terphenyl, 3-fluoroisophthalic acid, 2-fluoroisophthalic acid, 2-fluoroterephthalic acid, 2,4,5,6- Tetrafluoroisophthalic acid, 2,3,5,6-tetrafluoroterephthalic acid, 5-
Examples thereof include trifluoromethylisophthalic acid, which may be used alone or in combination of two or more kinds.

In the polyamide of the present invention, L and M in formula (1) are the number of repeating units having a biphenylene skeleton and the number of repeating units having no biphenylene skeleton.
, L and M are L> 0, M ≧ 0, 2 ≦ L + M ≦
It is an integer that satisfies 1000 and 0.05 ≦ L / (L + M) ≦ 1. The sum of L and M is preferably 5 or more and 100 or less. Here, if the sum of L and M is less than 2, the polymer electrolyte becomes brittle and the mechanical strength becomes insufficient. On the other hand, when it exceeds 1000, the molecular weight becomes too large and it becomes difficult to dissolve in a solvent, or even if it dissolves, it becomes a viscous varnish, which is not suitable for practical use. L and M are 0.05 ≦ L / (L + M)
It is essential that it be an integer satisfying ≦ 1, and further,
It is preferable that 0.5 ≦ L / (L + M) ≦ 1 is satisfied.
When 0.05> L / (L + M), it means that the number of repeating units having a biphenylene skeleton is small, and since there are few crosslinking reaction sites, heat resistance is not improved, which is not preferable.

In the present invention, as a method for producing the polyamide which is an essential component, a conventional acid chloride method, an activated ester method, a condensation reaction in the presence of a dehydration condensation agent such as polyphosphoric acid or dicyclohexylcarbodiimide, etc. are used. You can For example, in the acid chloride method, the acid chloride used is obtained by first dicarboxylic acid and an excess amount of thionyl chloride in the presence of a catalyst such as N, N-dimethylformamide.
It can be obtained by reacting at room temperature to 130 ° C., distilling off excess thionyl chloride by heating and reducing pressure, and recrystallizing the residue with a solvent such as hexane. When the dicarboxylic acid chloride produced in this manner and the other dicarboxylic acid are used in combination, the acid chloride obtained in the same manner is used together with a bisaminophenol compound, usually N-
A polyamide can be obtained by dissolving it in a polar solvent such as methyl-2-pyrrolidone or N, N-dimethylacetamide and reacting it at room temperature to -30 ° C in the presence of an acid acceptor such as pyridine.

In the present invention, the oligomer which is an essential component is specifically exemplified by polyoxymethylene, polyoxyethylene, polyoxymethylene-oxyethylene copolymer, polyoxymethylene-oxypropylene copolymer and polyoxymethylene-oxypropylene copolymer. Preferable examples include polyoxyalkylenes such as oxyethylene-oxypropylene copolymers. Of these, the general formula _{- (C x H 2x -O)} m - repeating a unit represented by - [CH (R ¹⁾ -CH ₂ -O] _n
A repeating unit represented by − (in each repeating unit, x is an integer of 1 to 6, and m and n are m ≧ 0 and n ≧
0, m + n ≧ 5, and R ¹ represents an alkyl group having 1 to 6 carbon atoms or a benzyl group) is more preferable. Further, the more preferable oligomer can adjust the holding power of the electrolytic solution by adjusting the ratio of the ethylene oxide segment and the propylene oxide segment. Preferably, the propylene oxide segment is 30 to 100% by weight in the oligomer. If it is less than 30% by weight, the holding power may be lowered and gelation may not occur. Further, the retention rate of the electrolytic solution can be adjusted by the blending ratio with the polyamide.

In the present invention, the oligomer can be used as a copolymer by reacting with a carboxy group, an amino group, a hydroxyl group at the terminal of a polyamide resin, or a hydroxyl group in the main chain structure. In this case, a functional group such as a hydroxyl group, an amino group, a nitro group, a carboxy group, a cyano group or a methacrylic group introduced at one end or both ends of the oligomer can be used. Also, as a specific example,
For example, Jeffamine (trade name) in which both ends of polypropylene glycol, which is the preferred oligomer, is replaced with amine, and diethylene glycol bispropylamine [H ₂ N (CH ₂ )] in which an ether group is introduced into a linear aliphatic diamine _p -O- (CH ₂ CH
_{2 O) q - (CH 2} ) p -NH 2 ] and the like.
These organic compounds may be used alone or in combination of two or more.

The polymer component used in the present invention comprises a composition obtained by mixing a polyamide and an oligomer or a copolymer obtained by reacting these. The weight ratio of the polyamide to the oligomer in the polymer component is preferably 20:80 to 60:40 so as to be blended or copolymerized. When the proportion of polyamide is out of the above range, there is a possibility that neither gelation occurs.

The content of the polymer component in the polymer electrolyte of the present invention is preferably 5% by weight or more in order to enhance the holding power of the electrolytic solution, and 70% by weight or less in order to enhance the ionic conductivity. It is preferable.

As the non-aqueous solvent used as the solvent component of the electrolytic solution used in the present invention, an ester is preferable, and an ester having a particularly low molecular weight and a high dielectric constant (dielectric constant of 30 or more) is used.
Is preferred. Examples of such an ester having a low molecular weight and a high dielectric constant include ethylene carbonate, propylene carbonate, butylene carbonate, gamma-butyrolactone, and ethylene glycol sulfite. Among them, those having a cyclic structure are preferable, and particularly ethylene carbonate. Cyclic carbonates such as In addition to the above esters, for example, chain carbonates such as dimethyl carbonate, diethyl carbonate and methyl ethyl carbonate, chain phosphate triesters such as trimethyl phosphate, 1,2-dimethoxyethane, 1,3-dioxolane, Tetrahydrofuran,
Ethers such as 2-methyl-tetrahydrofuran and diethyl ether can also be used. Furthermore, amine-based or imide-based organic solvents, sulfur-based organic solvents such as sulfolane, and the like can also be used.

As the electrolyte salt used in the present invention, for example,
For example, LiClO_Four, LiPF₆, LiBF_Four, LiAs
F₆, LiSbF₆, LiCF₃SO₃, LiC_FourF₉
SO₃, LiCF₃CO₂, Li₂C₂F_Four(SO₃)
₂, LiN (RfSO₂) (Rf'SO₂), LiN
(RfOSO₂) (Rf'OSO₂), LiC (RfS
O₂ ), LiC_wF_{2w + 1}SO₃(W ≧ 2), LiN (R
fOSO₂)₂[Where Rf and Rf ′ are fluoro groups
Group, etc., each of which is independent.
Alternatively, two or more kinds can be mixed and used. And this
As an electrolyte salt of
Because it is easy to separate, it does not easily dissolve in a non-aqueous solvent.
Elemental organic lithium salt, especially fluorine-containing organic lithium having 2 or more carbon atoms
The thium salt is preferred. Concentration of electrolyte salt in electrolyte
Is not particularly limited, but is 0.3 mol / l
The above is preferable, and 0.7 mol / l or more is more preferable.
And preferably 1.7 mol / l or less, 1.5 m
It is more preferably ol / l or less.

In the present invention, in addition to the above components,
When a compound having a C = C unsaturated bond is added as an additive to the electrolytic solution, it is possible to suppress deterioration of cycle characteristics when the negative electrode mixture layer is densified. As such a compound having a C═C unsaturated bond, for example, H
(CF ₂ ) ₄ CH ₂ OOCCH = CH ₂ , F (CF ₂ ) ₈
Examples thereof include fluorinated compounds having an ester bond such as CH ₂ CH ₂ OOCCH═CH ₂ .

The polymer electrolyte of the present invention comprises a polymer component composed of a composition or copolymer obtained from the above polyamide and oligomer, and an electrolyte salt such as LiCF ₃ SO.
₃ (to be 1.0 mol / l) is added to a solution composed of a non-aqueous solvent, and the mixture is stirred until it is uniformly dissolved to obtain an electrolytic solution. A polybutylene terephthalate non-woven fabric having an average thickness of 80 μm is dipped in the electrolytic solution, pulled up and left for 5 hours to prepare a polymer electrolyte using the polybutylene terephthalate non-woven fabric as a support. All the above operations are performed in a dry atmosphere with a dew point temperature of -60 ° C or lower.

The polymer electrolyte of the present invention can be used alone or in combination with other constituents such as impregnating a separator in a secondary battery having at least a positive electrode and a negative electrode. For example, the polymer electrolyte of the present invention is placed between a positive electrode and a negative electrode, applied to the surface of a positive electrode or a negative electrode, impregnated in a positive electrode or a negative electrode, and made into a component of a battery. . When the polymer electrolyte of the present invention is used instead of the conventionally used electrolytic solution, such as disposing the polymer electrolyte of the present invention between the positive electrode and the negative electrode as described above, a battery having high safety and reliability should be configured. You can Further, even when using the electrolytic solution, when the polymer electrolyte of the present invention is applied to the surface of the positive electrode or the negative electrode, or when the polymer electrolyte of the present invention is impregnated in the positive electrode or the negative electrode, decomposition of the electrolytic solution on the electrode Since the reaction can be suppressed, a battery having excellent storage characteristics can be constructed.

Next, an example in which a secondary battery is constructed using the polymer electrolyte of the present invention is shown below. For the positive electrode, as an active material, for example, lithium cobalt oxide such as LiCoO ₂ , lithium manganese oxide such as LiMn ₂ O _4, or lithium-containing composite oxide such as lithium nickel oxide such as LiNiO ₂ is used. It is also possible to use, based on these lithium-containing composite oxides, those partially substituted with other elements. Examples of the lithium-containing composite oxide partially substituted with such other element include LiNi _0.7 Co _0.2 Al _0.1 O ₂ .
Further, metal oxides such as manganese dioxide, vanadium pentoxide, and chromium oxide, and metal sulfides such as titanium disulfide and molybdenum disulfide can also be used as the active material of the positive electrode. Further, a sulfur element such as polysulfur or an organic sulfur compound having a disulfide bond can be used as the active material of the positive electrode.

For the positive electrode, for example, a conductive aid such as scaly graphite, acetylene black or carbon black or a binder such as polyvinylidene fluoride or polytetrafluoroethylene is added to the above positive electrode active material, if necessary, and mixed. To prepare a positive electrode mixture, disperse it in a solvent to form a paste (the binder may be dissolved in the solvent in advance and then mixed with the positive electrode active material, etc.), and the positive electrode mixture-containing paste is used for a metal foil or the like. It is produced by applying a positive electrode current collector made of, and drying it to form a positive electrode mixture layer on at least a part of the positive electrode current collector. However, the method for producing the positive electrode is not limited to the above-exemplified method, and other methods may be used.

As the positive electrode current collector for the production of the positive electrode, for example, a metal material such as aluminum, nickel or stainless steel is used.
In order to increase the capacity, it is preferable to use a thin metal foil having a thickness of 15 μm or less. In a normal lithium ion secondary battery, a high-purity (99.9% by weight or more) aluminum foil is used as a positive electrode current collector, but when the thin aluminum foil is used as described above, it is not It is preferable to add the above-mentioned metal so that the metal has such strength that it can be used even if it is thin. Particularly preferable metals to be added to such aluminum are iron and silicon. The amount of iron added is preferably 0.5% by weight or more, and preferably 2% by weight or less. The amount of silicon added is preferably 0.1% by weight or more and 1% by weight or less.

Examples of the active material used for the negative electrode include lithium, lithium alloys and the like, and carbon materials such as graphite, cokes, mesocarbon microbeads, carbon fibers and activated carbon. Further, an alloy or oxide of Si, Sn, In, or the like, or a lithium-containing composite nitride can also be used as the negative electrode active material. Among them, lithium, lithium alloys, lithium-containing composite nitrides and the like are preferable for designing high capacity batteries.

The negative electrode is prepared, for example, by adding the same conductive auxiliary agent and binder as in the case of the positive electrode to the above negative electrode active material and mixing them to prepare a negative electrode mixture, which is then dispersed in a solvent. To form a paste (the binder may be dissolved in a solvent in advance and then mixed with the negative electrode active material),
The negative electrode mixture-containing paste is applied to a negative electrode current collector made of copper foil or the like, and dried to form a negative electrode current collector layer on at least a part of the negative electrode current collector, which is manufactured. However, the method for producing the negative electrode is not limited to the above-exemplified method, and other methods may be used. As the negative electrode current collector, for example, a metal foil such as copper, aluminum, nickel, and stainless steel, or a mesh of those metals is used.

[0033]

EXAMPLES Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to only those examples. In the following examples and the like,% indicating concentration, composition, yield and the like is% by weight unless otherwise specified.

(Synthesis Example 1) 2,2-bis (3-amino-)
4-hydroxyphenyl) hexafluoropropane 3
6.6 g (0.1 mol) and one-end aminated polypropylene glycol (Jeffa manufactured by Huntsman, USA)
40 g of mineXTJ-502 [(trade name), AHEW (active hydrogen equivalent) = 525] was dissolved in 100 g of dried dimethylacetamide, and 19.8 g of pyridine (0.2
5 mol), then γ-butyrolactone 35 g
In addition, 11.5 g of isophthalic acid chloride (0.049 mo)
l) and 2,6-biphenylenedicarboxylic acid chloride 1
A solution in which 5.1 g (0.049 mol) was dissolved was added dropwise under dry nitrogen at -15 ° C over 30 minutes. After the dropping is completed,
It returned to room temperature and stirred at room temperature for 5 hours. Then, the reaction solution was added dropwise to 3 liters of ion-exchanged water, and the precipitate was collected and dried to obtain 52 g of polyamide. When the number average molecular weight (Mn) of the obtained polyamide was calculated in terms of polystyrene using GPC manufactured by Tosoh Corporation, it was 2
It was 2000.

(Synthesis Example 2) In Synthesis Example 1, one-terminal aminated polypropylene glycol (Jeffamine) was used.
XTJ-502) in place of aminated polypropylene glycol at both ends (Jef manufactured by Huntsman, USA).
familyD-400 ((trade name, AHEW = 10
0)) 40 g, the amount of isophthalic acid chloride was 22.8 g (0.097 mol), and the amount of 2,6-biphenylenedicarboxylic acid chloride was 0.3 g (0.000).
46 g of polyamide was obtained in the same manner as in Synthesis Example 1 except that the amount was changed to 1 mol). The number average molecular weight (Mn) of the obtained polyamide was 25,000 when calculated in terms of polystyrene using GPC manufactured by Tosoh Corporation.

Example 1 Polymer Obtained in Synthesis Example 1 (to 10% by Weight)
And LiCF ₃ SO ₃ (to be 1.0 mol / l)
Was added to a solution [a mixed solvent of methyl ethyl carbonate (MEC) and ethylene carbonate (EC) in a weight ratio of 1: 1], and the mixture was stirred until it was uniformly dissolved to prepare an electrolytic solution.

A polybutylene terephthalate non-woven fabric having an average thickness of 80 μm was dipped in the above electrolytic solution, and after being pulled up, 5
After standing for a time, a polymer electrolyte having a polybutylene terephthalate nonwoven fabric as a support was prepared. All the above operations were performed in a dry atmosphere with a dew point temperature of -60 ° C or lower. Regarding the obtained polymer electrolyte, the polymer content was 8%, and the concentration of LiCF ₃ SO _{3 in} the electrolyte salt was 1.0 m.
It was adjusted to be ol / l, and the ionic conductivity at room temperature was measured and found to be 2.0 × 10 ⁻³ S · cm ⁻¹ . A secondary battery was prepared by combining this polymer electrolyte with the positive electrode, the negative electrode, and the like shown below.

A flake graphite as a conductive additive was added to LiCoO ₂ at a weight ratio of 100: 6 and mixed, and the resulting mixture and a solution in which polyvinylidene fluoride was dissolved in N-methyl-2-pyrrolidone in advance. And were mixed to prepare a positive electrode mixture-containing paste. The positive electrode mixture-containing paste was passed through a stainless steel net to remove agglomerates, and then the thickness was 15 μm, iron was 1% and silicon was 0.1%.
The weight of the positive electrode mixture after drying is 24.6 m per unit area on both sides of the positive electrode current collector made of aluminum foil containing 15%.
It is evenly coated so as to be g / cm ² and dried to form a positive electrode mixture layer, which is then compression-molded by a roller press, then cut, and a lead body is welded to produce a strip-shaped positive electrode. did.

Next, the interplanar distance (d ₀₀₂ ) of the (002) plane is 0.337 nm, the crystallite size (Lc) in the c-axis direction is 95.0 nm, the average grain size is 15 μm, and the purity is 99. ≧ 9% mesocarbon microbeads
A negative electrode mixture-containing paste was prepared by mixing polyvinylidene fluoride with a solution prepared by dissolving N-methyl-2-pyrrolidone in advance. The negative electrode mixture-containing paste was passed through a stainless steel net to remove aggregates, and then the negative electrode current collector made of strip-shaped copper foil having a thickness of 10 μm had a coating amount after drying of 12.0 mg / cm ² to evenly coat and dry to form a negative electrode mixture layer,
Compression molding with a roller press machine, then cutting,
The lead body was welded to produce a strip-shaped negative electrode.

The surfaces of the strip-shaped positive electrode and the strip-shaped negative electrode were treated with an electrolyte solution (a mixed solvent of methylethyl carbonate and ethylene carbonate in a weight ratio of 2: 1) with LiCF ₃ SO 4.
₃ was slightly moistened with 1.0 mol / l of a solution), and the above polymer electrolyte was interposed between the two to make a spiral winding, to produce a laminated electrode body having a spiral winding structure.
This laminated electrode body is filled in a cylindrical battery case, the positive electrode and negative electrode lead bodies are welded, then sealed, precharged and aged, and a tube having a structure as shown in the schematic view of FIG. The secondary battery of the shape was produced.

The battery shown in FIG. 1 will be briefly described below. 1 is the positive electrode, 2 is the negative electrode, and 3 is a polymer prepared by using the polybutylene terephthalate nonwoven fabric as a support as described above. It is an electrolyte. However, in FIG. 1, in order to avoid complication, the metal foil used as a current collector in the production of the positive electrode 1 and the negative electrode 2 and the polybutylene terephthalate nonwoven fabric used as a support in the production of the polymer electrolyte are not shown.
The positive electrode 1 and the negative electrode 2 are spirally wound via the polymer electrolyte 3 and housed in a battery case 4 made of stainless steel as a laminated electrode body having a spiral spiral structure.

The battery case 4 also serves as a negative electrode terminal, the insulator 5 is arranged on the bottom thereof, and the insulator 6 is also arranged on the laminated electrode body. Then, a sealing body 8 is arranged in the opening of the battery case 4 via an annular insulating packing 7, and the inside of the battery is sealed by tightening the opening end of the battery case 4 inward. However, the sealing body 8 incorporates an irreversible vent mechanism for preventing the gas generated inside the battery from rupturing under high pressure by discharging the gas to the outside of the battery when it rises to a certain constant pressure. Has been.

Example 2 The polymer obtained in Synthesis Example 2 (to be 12% by weight) and LiCF ₃ SO ₃ (to be 1.0 mol / l) were dissolved in a solution [methyl ethyl carbonate (MEC)]. It was added to a mixed solvent having a weight ratio of 1: 1 with ethylene carbonate (EC), and stirred until it was uniformly dissolved to prepare an electrolytic solution.

A polybutylene terephthalate non-woven fabric having an average thickness of 80 μm was dipped in the above electrolytic solution, and after pulling up, 5
After standing for a time, a polymer electrolyte having a polybutylene terephthalate nonwoven fabric as a support was prepared. Then, in the same manner as in Example 1, a polyelectrolyte was prepared using a polybutylene terephthalate nonwoven fabric as a support. The obtained polymer electrolyte was adjusted so that the polymer content was 10% and the concentration of LiCF ₃ SO ₃ in the electrolyte salt was 1.0 mol / l, and the ionic conductivity was measured. 1
It was 0 ⁻³ S · cm ⁻¹ .

Comparative Example 1 A film-shaped polymer electrolyte having a conventional structure was produced by the method described below. 220 g of tri- (ethylene glycol) dimethacrylate and 2-ethoxy acrylate 8.
5 g and ethylene glycol ethyl carbonate methacrylate 5.6 g were used, and the composition was 1.22 mol / l Li.
A solution represented by PF ₆ / PC: EC (1: 1 weight ratio) [LiPF _{6 in} a mixed solvent of propylene carbonate (PC) and ethylene carbonate (EC) in a weight ratio of 1: 1.
Was dissolved in 1.22 mol / l] 1.4 kg, and further 20 g of benzoyl peroxide was dissolved. Polybutylene terephthalate non-woven fabric was impregnated with this solution, placed in a polyethylene plate frame having a thickness of 80 μm, heated to 80 ° C., heated and pressed at 45 kg / cm ² for 10 minutes, kept cold, and then the plate frame. It was taken out further and cut into a suitable size to obtain a polymer electrolyte. All the above operations were performed in a dry atmosphere with a dew point temperature of -60 ° C or lower. The ionic conductivity of the obtained polymer electrolyte was 1.0 × 10 ⁻³ S · cm ⁻¹ . A tubular secondary battery was produced in the same manner as in Example 1 except that the conventional polymer electrolyte produced as described above was used.

The discharge capacities of the batteries of Examples 1 and 2 and Comparative Example 1 were measured, and the results are shown in Table 1. The method for measuring the discharge capacity is as follows. Discharge capacity: The batteries of Examples 1 and 2 and Comparative Example 1 were charged and discharged at a current value of 300 mA in a voltage range of 2.75 to 4.1 V, and the first discharge capacity was measured.

[0047]

[Table 1]

As described above, the examples are
A polymer electrolyte having a high ionic conductivity was obtained, and the secondary battery using the polymer electrolyte had a large discharge capacity.

[0049]

According to the present invention, it is possible to provide a polymer electrolyte having high ionic conductivity, excellent quality stability, and high capacity, and by using the polymer electrolyte,
A high-performance and highly safe secondary battery can be provided.

[Brief description of drawings]

FIG. 1 shows a schematic view of a secondary battery manufactured in an example.

[Explanation of symbols]

1 positive electrode 2 Negative electrode 3 Polymer electrolyte 4 battery case 5,6 insulator 7 Insulation packing 8 Sealing body

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Claims (3)

[Claims] 1. A polymer electrolyte comprising a polymer component comprising a polyamide having a repeating unit represented by the general formula (1) and an oligomer, an electrolyte salt and a non-aqueous solvent. [Chemical 1] (However, L and M in the formula are L> 0, M ≧ 0, 2 ≦ L
+ M ≦ 1000, and an integer that satisfies 0.05 ≦ L / (L + M) ≦ 1. X is a tetravalent group represented by the formula (2), Y is a divalent group represented by the formula (3), and Z is a formula (4).
The groups selected from the divalent groups represented by are shown below. ) [Chemical 2] [Chemical 3] [Chemical 4] (However, in the formulas (2) and (4), X ₁ represents a group selected from the divalent groups represented by the formula (5). Further, the formula (2), the formula (3), The hydrogen atom on the benzene ring in the groups represented by formula (4) and formula (5) is a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, a fluorine atom, and It may be substituted with at least one group selected from trifluoromethyl groups.) 2. The oligomer has at least the general formula:
The repeating unit represented by (C _x H _2x -O) _m- and-[C
Repeating unit represented by H (R ¹ ) —CH ₂ —O] _n — (in each repeating unit, x is an integer of 1 to 6, and m
And n are m ≧ 0, n ≧ 0, m + n ≧ 5, and R ¹ represents an alkyl group having 1 to 6 carbon atoms or a benzyl group). 3. A secondary battery comprising at least a positive electrode, a negative electrode and the polymer electrolyte according to claim 1.