JP2002198094A - Polymer electrolyte, lithium secondary cell and production process of lithium secondary cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymer electrolyte which has excellent heat resistance, is not melted even at a high temperature and may surely exist in a cell, a lithium secondary cell equipped with the polymer electrolyte and a production process of the lithium secondary cell. SOLUTION: The lithium secondary cell adopts a polymer electrolyte comprising at least an acid polymer having a plurality of acidic groups, a basic compound having a valence of at least 2, which reacts with the acidic groups, thereby crosslinking the acid polymer, and an organic electrolyte with a lithium salt dissolved in an aprotic solvent, wherein the acid polymer is crosslinked by the basic compound, and the acid polymer is gelled by the organic electrolyte.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer electrolyte and a lithium secondary battery provided with the polymer electrolyte, and a method for manufacturing the lithium secondary battery.

[0002]

2. Description of the Related Art In order to meet the needs of portable electronic devices that are becoming smaller and lighter and have higher performance, there is a demand for further reduction in the thickness of lithium secondary batteries and improvement in the degree of freedom in shape. Therefore, recently, by replacing the electrolyte of a lithium secondary battery from a conventional organic electrolyte with a polymer electrolyte,
Lithium secondary batteries with a reduced thickness and improved shape flexibility have been provided.

[0003] The above-mentioned polymer electrolytes are roughly classified into two types, physical gels and chemical gels, depending on the manufacturing method. The physical gel is formed by dissolving the polymer by adding an organic electrolyte solution to the polymer and heating to form a paste.The paste is applied to a sheet-shaped positive electrode, and the negative electrode is applied to the paste after application. By laminating the unit cells and storing and closing the unit cells in a battery container, the paste is cooled in the battery container to form a physical gel as a gel polymer electrolyte. As the above-mentioned high-molecular polymer, a material which is easily swelled and gelled by an organic electrolyte at room temperature and is dissolved by an organic electrolyte at about 80 to 100 ° C. is selected.

On the other hand, for the chemical gel, for example, a sheet-like positive electrode, a nonwoven fabric, and a negative electrode are laminated to form an electrode group, and then the electrode group is housed in a battery container, and an organic electrolyte and a polymerization initiator are injected. Further, for example, a monomer having a vinyl group is injected. As a result, the polymerization initiator reacts with the monomer, and the monomer is polymerized in the battery container, whereby a chemical gel as a gel polymer electrolyte is formed. As the above-mentioned monomer, a monomer that can swell with an organic electrolyte at room temperature to produce a polymer that easily gels is selected.

The above-mentioned physical gel and chemical gel have a thickness of 2-3 m.
Since it has an ion conductivity of about S / cm, it can be applied as an electrolyte of a lithium secondary battery.

[0006]

However, in a lithium secondary battery using the above-mentioned physical gel, when the battery temperature rises due to, for example, an external factor, the polymer constituting the physical gel is converted into an organic electrolyte. There is a problem that the anode and the anode are short-circuited due to dissolution and liquefaction, thereby causing an internal short circuit.

On the other hand, in a lithium secondary battery using the above-described chemical gel, an unreacted polymerization initiator remains in the battery and adversely affects the charge / discharge reaction of the battery, or the reaction between the polymerization initiator and the monomer may occur. There has been a problem that gas is generated in the battery with the reaction, and further, a case where the polymerization reaction of the monomer is insufficient occurs so that a polymer electrolyte is not formed.

The present invention has been made in view of the above circumstances, and comprises a polymer electrolyte which is excellent in heat resistance, does not dissolve even at high temperatures, and can be surely present in a battery, and a polymer electrolyte comprising the polymer electrolyte. It is an object of the present invention to provide a lithium secondary battery and a method for manufacturing the lithium secondary battery.

[0009]

In order to achieve the above object, the present invention employs the following constitution. The polymer electrolyte of the present invention comprises an acidic polymer having a plurality of acidic groups, at least a divalent or more basic compound which crosslinks the acidic polymer by reacting with the acidic group, and a lithium salt dissolved in an aprotic solvent. The acidic polymer is cross-linked by the basic compound to form a cross-linked body, and the organic electrolyte is retained by the cross-linked body, and at least the acidic polymer Are gelled by the organic electrolytic solution.

According to such a polymer electrolyte, the acidic polymer is crosslinked by the basic compound and the acidic polymer is gelled by the organic electrolytic solution. The liquid can be held, and a polymer electrolyte having excellent heat resistance can be formed. Further, since the acidic polymer has a structure crosslinked by the basic compound, the crosslinked structure is not broken at a high temperature. Further, since the cross-linking is a compound of an acid-base, the reaction rate is extremely high, the cross-linking structure is formed uniformly, and there is no possibility that the cross-linking becomes insufficient.

[0011] The polymer electrolyte of the present invention comprises a basic polymer having a plurality of basic groups and at least two basic groups which react with the basicity to crosslink the basic main chain polymer.
At least an acidic compound having a valency or higher, and an organic electrolytic solution obtained by dissolving a lithium salt in an aprotic solvent, wherein the basic polymer is crosslinked by the acidic compound to form a crosslinked body, An organic electrolytic solution is held by the crosslinked body, and at least the basic polymer is gelled by the organic electrolytic solution.

According to such a polymer electrolyte, since the basic polymer is crosslinked by the acidic compound and the basic polymer is gelled by the organic electrolyte, the basic polymer and the acidic compound are not dissociated and the organic polymer is not dissociated. An electrolyte can be retained, and a polymer electrolyte having excellent heat resistance can be formed. Further, since the basic polymer has a structure crosslinked by the acidic compound, the crosslinked structure does not break at high temperatures. Further, since the cross-linking is a compound of an acid-base, the reaction rate is extremely high, the cross-linking structure is formed evenly, and there is no possibility that the cross-linking becomes insufficient.

Further, the polymer electrolyte of the present invention comprises a basic polymer having a plurality of basic groups, an acidic polymer having a plurality of acidic groups, and an organic electrolyte obtained by dissolving a lithium salt in an aprotic solvent. At least have
A polymer complex is formed by the combination of the basic group of the basic polymer and the acidic group of the acidic polymer, and the organic electrolytic solution is retained by the polymer composite, and the basic polymer or the acidic polymer is retained. One or both of the polymers are gelled by the organic electrolyte.

According to the polymer electrolyte, the acidic polymer and the basic polymer form a polymer composite, and one or both of the basic polymer and the acidic polymer are gelled by the organic electrolyte.
The organic electrolyte can be held without dissociation of the basic polymer and the acidic polymer, and a polymer electrolyte having excellent heat resistance can be formed. Further, since the polymer composite is composed of a basic polymer and an acidic polymer, the crosslinked structure is not broken at a high temperature. Further, since the cross-linking is a compound of an acid-base, the reaction rate is extremely high, the cross-linking structure is formed evenly, and there is no possibility that the cross-linking becomes insufficient.

In the above-mentioned polymer electrolyte, it is preferable that the acidic group of the acidic polymer is one of a carboxyl group and a sulfonic acid group.

According to such a polymer electrolyte, the acidic polymer has either a carboxyl group or a sulfonic acid group, and since these groups have a relatively high acidity, they are combined with a basic compound to form a strong compound. It becomes possible to form a crosslinked structure.

In the above-mentioned polymer electrolyte, it is preferable that the basic group of the basic polymer is either a pyridyl group or a dimethylamino group.

According to such a polymer electrolyte, the basic polymer has either a pyridyl group or a dimethylamino group, and since these groups have a relatively high basicity, they are combined with an acidic compound to be strong. It becomes possible to form a suitable crosslinked structure.

The polymer electrolyte of the present invention is the polymer electrolyte described above, wherein the acidic polymer or the basic polymer has an easily gelling functional group which is gelled by the organic electrolyte. It is characterized by the following.

According to the polymer electrolyte, the above-mentioned easily gellable group dissolves in the organic electrolyte and gels, so that the entire acidic or basic polymer can be gelled by the organic electrolyte, It becomes possible to express the high ionic conductivity by holding the liquid.

In the above-mentioned polymer electrolyte, it is preferable that the easily gelling functional group is one of a cyano group and a methoxycarbonyl group.

According to such a polymer electrolyte, one of a cyano group and a methoxycarbonyl group is provided as a gelling functional group, and these groups exhibit high solubility in an organic electrolytic solution. The basic polymer can be easily gelled.

In the polymer electrolyte of the present invention, the acidic polymer is preferably one represented by the following [Chemical Formula 3].

[0024]

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However, the substituent R ₁ is either H or CH ₃ , the substituent X ₁ is the above-mentioned gelling functional group and is either COOCH ₃ or CN, and the substituent Y ₁ Is the above-mentioned acidic group, which is either COOH or SO ₃ H, n ₁ is in the range of 100 to 10,000, and n ₂ is in the range of 10 to 1,000.

Further, in the polymer electrolyte of the present invention, it is preferable that the basic polymer is represented by the following chemical formula (4).

[0027]

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However, the substituent R_TwoIs H or CH_ThreeNozomi
But the substituent X_TwoIs the easily gelling functional group.
Tte COOCH_ThreeOr CN
Substitution Y_TwoIs the aforementioned basic group and is C_FiveH_FourN or Cm₁H2
m₁N (CH_Three)_Two(However, 0 ≦ m₁Any one of ≦ 10)
And n_ThreeIs in the range of 100 to 10000, and n _Four
Is in the range of 10-1000.

In the polymer electrolyte of the present invention, the acidic compound is preferably one represented by any of the following (1) to (6). _{HOOC-Cm 2 H2m 2 -COOH (} 1) HOOC- (CH 2 O) m 3 -COOH (2) HOOC- (C 2 H 4 O) m 3 -COOH (3) HO 3 S-Cm 4 H2m 4 - SO ₃ H (4) HO ₃ S— (CH ₂ O) m ₅ —SO ₃ H (5) HO ₃ S— (C ₂ H ₄ O) m ₅ —SO ₃ H (6) where m ₂ and m ₃ , M ₄ and m ₅ are respectively 0 ≦ m ₂ ≦ 50
1 ≦ m ₃ ≦ 50, 0 ≦ m ₄ ≦ 50, and 1 ≦ m ₅ ≦ 50.

Further, in the polymer electrolyte of the present invention,
The basic compound is trimethylolpropane-tri-β-azir
idinylpropionate, tetramethylomethane-tri-β-aziri
dinylpropionate, trimethylopropane-tris (2-methyl-1
-aziridinepropionate), N, N-hexamethylene-1,6-bis (1
-aziridinecarboxamide), N, N, N ', N'-tetramethylethyl
enediamine, N, N, N ', N'-tetramethyldiaminomethane,
N, N, N ', N'-tetramethyl-1,3-propanediamine, N, N, N',
N'-tetramethyl-1,4-buthanediamine, N, N, N ', N'-tetra
methyl-1,6-hexanediamine, N, N, N ', N'-tetramethyl-1,
3-butanediamine, N, N, N ', N'-tetramethyl-1,4-phenyle
Preferably, it is any one of ndiamines.

[0031] A lithium secondary battery according to the present invention is characterized by comprising the polymer electrolyte described in any of the above, and a positive electrode and a negative electrode capable of inserting and extracting lithium.

According to such a lithium secondary battery, since the above-mentioned polymer electrolyte is provided, there is no danger that the polymer electrolyte will be liquefied at a high temperature or the problem of insufficient formation of the polymer electrolyte will not occur, resulting in excellent safety. In addition, it becomes possible to configure a lithium secondary battery having excellent cycle characteristics.

Next, a method for manufacturing a lithium secondary battery according to the present invention is directed to a method for manufacturing a lithium secondary battery including a polymer electrolyte, a sheet-shaped positive electrode and a negative electrode capable of inserting and extracting lithium. An acidic polymer having a plurality of acidic groups, at least a divalent or higher valent basic compound that crosslinks the acidic polymer by reacting with the acidic group, and a lithium salt dissolved in an aprotic solvent. A paste preparation step of mixing an organic electrolyte solution to obtain an electrolyte paste, and applying the electrolyte paste to one or both of the positive electrode and the negative electrode, and applying the positive electrode or the negative electrode on the applied electrolyte paste. A unit cell manufacturing step of stacking one of the other units to form a unit cell.

According to the method for manufacturing a lithium secondary battery, the electrolyte paste is applied to one or both of the positive electrode and the negative electrode, and the other of the positive electrode and the negative electrode is laminated on the applied electrolyte paste. By doing
A polymer electrolyte can be easily formed by crosslinking an acidic polymer with a basic compound, and the productivity of a lithium secondary battery can be increased. Further, since a polymerization initiator is unnecessary, a reaction product of the polymerization initiator does not remain in the polymer electrolyte and does not adversely affect the charge / discharge reaction.

The method for producing a lithium secondary battery according to the present invention is directed to a method for producing a lithium secondary battery comprising a polymer electrolyte, a sheet-like positive electrode and a negative electrode capable of inserting and extracting lithium. And a basic polymer having a plurality of basic groups, at least a divalent or higher acidic compound which crosslinks the basic polymer by reacting with the basic group, and a lithium salt dissolved in an aprotic solvent. A paste preparing step of mixing an organic electrolyte solution to obtain an electrolyte paste, and applying the electrolyte paste to one or both surfaces of the positive electrode or the negative electrode, and applying the electrolyte paste on the electrolyte paste after application. A unit cell manufacturing step of stacking one of the positive electrode and the negative electrode to form a unit cell.

According to the method for manufacturing a lithium secondary battery, the electrolyte paste is applied to one or both of the positive electrode and the negative electrode, and one of the positive electrode and the negative electrode is laminated on the applied electrolyte paste. By doing
A polymer electrolyte can be easily formed by crosslinking a basic polymer with an acidic compound, and the productivity of a lithium secondary battery can be increased. Further, since a polymerization initiator is unnecessary, a reaction product of the polymerization initiator does not remain in the polymer electrolyte and does not adversely affect the charge / discharge reaction.

The method for manufacturing a lithium secondary battery according to the present invention is a method for manufacturing a lithium secondary battery comprising a polymer electrolyte, a sheet-like positive electrode and a negative electrode capable of inserting and extracting lithium. There is a paste preparation for obtaining an electrolyte paste by mixing a basic polymer having a plurality of basic groups, an acidic polymer having a plurality of acidic groups, and an organic electrolyte obtained by dissolving a lithium salt in an aprotic solvent. A process for applying the electrolyte paste to one or both of the positive electrode and the negative electrode, and laminating the other of the positive electrode and the negative electrode on the applied electrolyte paste to form a unit cell And a process.

According to the method for manufacturing a lithium secondary battery, the electrolyte paste is applied to one or both of the positive electrode and the negative electrode, and one of the positive electrode and the negative electrode is laminated on the applied electrolyte paste. By doing
A polymer electrolyte can be easily formed by combining an acidic polymer and a basic polymer, and the productivity of a lithium secondary battery can be increased. Further, since a polymerization initiator is unnecessary, a reaction product of the polymerization initiator does not remain in the polymer electrolyte and does not adversely affect the charge / discharge reaction.

The method for producing a lithium secondary battery according to the present invention comprises:
The method for manufacturing a lithium secondary battery according to the above, further comprising a heating step of heating the unit cell in a range of 40 to 85 ° C. for 10 to 600 minutes after the unit cell manufacturing step. It is characterized by.

According to the method for manufacturing a lithium secondary battery, since the unit cell obtained after the unit cell manufacturing process is subjected to a heat treatment, the polymer can be completely cross-linked by a basic or acidic compound, and the shape can be reduced. A stable polymer electrolyte can be obtained.

The method for producing a lithium secondary battery according to the present invention comprises:
A method for manufacturing a lithium secondary battery, comprising: a polymer electrolyte; a sheet-shaped positive electrode and a negative electrode capable of inserting and extracting lithium; and a battery container containing the polymer electrolyte, the positive electrode, and the negative electrode. An electrode group manufacturing step of interposing at least an acidic polymer having a plurality of acidic groups between the positive electrode and the negative electrode to form an electrode group, further storing the electrode group in the battery container, and crosslinking the acidic polymer A gelling solution is prepared by mixing at least a divalent or higher valent basic compound and an organic electrolyte obtained by dissolving a lithium salt in an aprotic solvent, and the gelling solution is used as an electrode group in the battery container. And a gelling step to be added to the mixture.

According to such a method for manufacturing a lithium secondary battery, an acidic polymer is inserted into a battery container in advance, and a basic compound is added together with an organic electrolytic solution to crosslink the acidic polymer. A polymer electrolyte can be formed, and the manufacturing process of a lithium secondary battery can be simplified to increase productivity. Also,
Since the polymerization initiator is unnecessary, the reaction product of the polymerization initiator does not remain in the polymer electrolyte to adversely affect the charge / discharge reaction, and no gas is generated due to the reaction of the polymerization initiator.

The method for producing a lithium secondary battery according to the present invention comprises:
A method for manufacturing a lithium secondary battery, comprising: a polymer electrolyte; a sheet-shaped positive electrode and a negative electrode capable of inserting and extracting lithium; and a battery container containing the polymer electrolyte, the positive electrode, and the negative electrode. An electrode group manufacturing step of interposing at least a basic polymer having a plurality of basic groups between the positive electrode and the negative electrode to form an electrode group, and further storing the electrode group in the battery container; A gelling solution is prepared by mixing at least a divalent or higher valent acidic compound for crosslinking a polymer and an organic electrolyte solution in which a lithium salt is dissolved in an aprotic solvent, and the gelling solution is mixed in the battery container. And a gelling step for adding to the electrode group.

According to the method of manufacturing a lithium secondary battery, a basic polymer is inserted into a battery container in advance,
Since the basic compound is cross-linked by adding an acidic compound together with the organic electrolyte later, a polymer electrolyte can be formed in the battery container, and the manufacturing process can be simplified for the lithium secondary battery to increase the productivity. Becomes possible. Further, since the polymerization initiator is unnecessary, the reaction product of the polymerization initiator does not remain in the polymer electrolyte and does not adversely affect the charge / discharge reaction, and no gas is generated due to the reaction of the polymerization initiator. .

The method for manufacturing a lithium secondary battery according to the present invention includes the steps of: accommodating a polymer electrolyte, a sheet-like positive electrode and a negative electrode capable of inserting and extracting lithium, and accommodating the polymer electrolyte, the positive electrode, and the negative electrode. A method for manufacturing a lithium secondary battery comprising a battery container, wherein between the positive electrode and the negative electrode, at least an acidic polymer having a plurality of acidic groups is interposed to form an electrode group, and further the electrode group is An electrode group manufacturing process to be housed in a battery container, a basic polymer having a plurality of basic groups, and an organic electrolyte solution in which a lithium salt is dissolved in an aprotic solvent to prepare a gelling solution, A gelling step of adding the gelling solution to the electrode group in the battery container.

Further, in the method for producing a lithium secondary battery of the present invention, a polymer electrolyte, a sheet-like positive electrode and a negative electrode capable of inserting and extracting lithium, and the polymer electrolyte, the positive electrode, and the negative electrode are housed. A method for manufacturing a lithium secondary battery comprising a battery container, wherein the electrode group is formed by interposing at least a basic polymer having a plurality of basic groups between the positive electrode and the negative electrode, and further comprising the electrode group An electrode group manufacturing process of housing the battery container, an acidic polymer having a plurality of acidic groups, and an organic electrolyte solution in which a lithium salt is dissolved in an aprotic solvent to prepare a gelling solution, A gelling step of adding the gelling solution to the electrode group in the battery container.

According to such a method for manufacturing a lithium secondary battery, one of an acidic polymer and a basic polymer is inserted into a battery container in advance, and the other of the acidic polymer and the basic polymer is later converted into an organic electrolyte. Since it is added together with the liquid to form a polymer composite, a polymer electrolyte can be formed in the battery container, and the production process can be simplified for a lithium secondary battery to increase productivity. Further, since the polymerization initiator is unnecessary, the reaction product of the polymerization initiator does not remain in the polymer electrolyte and does not adversely affect the charge / discharge reaction, and no gas is generated due to the reaction of the polymerization initiator. .

The method for manufacturing a lithium secondary battery according to the present invention comprises:
The method for producing a lithium secondary battery according to the above, further comprising a heating step of heating at 40 to 85 ° C. for 10 to 600 minutes after the gelation step.

According to the method for manufacturing a lithium secondary battery, since the battery is heat-treated after the gelling step, the polymer can be completely crosslinked by a basic or acidic compound, and a polymer electrolyte having a stable shape can be obtained. Obtainable.

[0050]

Embodiments of the present invention will be described below in detail. One of the polymer electrolytes of the present invention includes an acidic polymer having a plurality of acidic groups, at least a divalent or more basic compound that crosslinks the acidic polymer by reacting with the acidic group, and lithium as an aprotic solvent. At least an organic electrolytic solution in which a salt is dissolved, and the acidic polymer is crosslinked by the basic compound to form a crosslinked body, and the organic electrolytic solution is held by the crosslinked body, and at least the acidic The polymer is gelled by the organic electrolyte solution. Examples of the acidic group include a carboxyl group and a sulfonic acid group.

Another one of the polymer electrolytes of the present invention comprises a basic polymer having a plurality of basic groups and at least a divalent or higher valent compound which crosslinks the basic main chain polymer by reacting with the basic. An acidic compound and at least an organic electrolytic solution in which a lithium salt is dissolved in an aprotic solvent, and the basic electrolytic polymer is crosslinked by the acidic compound to form a crosslinked body, and the organic electrolytic solution is It is held in a crosslinked body and at least the basic polymer is gelled by the organic electrolyte. Examples of the basic group include a pyridyl group and a dimethylamino group.

Further, another one of the polymer electrolytes of the present invention comprises a basic polymer having a plurality of basic groups, an acidic polymer having a plurality of acidic groups, and a lithium salt dissolved in an aprotic solvent. And at least an organic electrolyte solution, and a polymer complex is formed by the combination of the basic group of the basic polymer and the acidic group of the acidic polymer, and the organic electrolyte solution is held by the polymer complex. In addition, one or both of the basic polymer and the acidic polymer are gelled by the organic electrolyte.

The polymer electrolyte of the present invention comprises an acidic polymer and a basic compound, or a basic polymer and an acidic compound,
Alternatively, the acidic polymer and the basic polymer are paired to form a crosslinked structure. For example, in the case of a combination of an acidic polymer and a basic compound, a monovalent base of the basic compound is bonded to the acidic group of the acidic polymer, and the remaining base of the basic compound is further converted to an acidic group of another acidic polymer. To join. In this way, a crosslinked body is formed by crosslinking the main chains of a plurality of acidic polymers with a basic compound. In the case of a combination of a basic polymer and an acidic compound, a monovalent acidic group of the acidic compound is bonded to the basic group of the basic polymer, and the remaining acidic group of the acidic compound is further converted to another basic polymer. To the basic group of In this manner, a crosslinked body is formed by crosslinking the main chains of the plurality of basic polymers with the acidic compound. In the case of a combination of a basic polymer and an acidic polymer, a polymer complex is formed by bonding the acidic group of the acidic polymer to the basic group of the basic polymer.

The organic electrolytic solution is held by the above-mentioned crosslinked product or polymer composite, and the acidic polymer or the basic polymer is gelled by the organic electrolytic solution. The acidic polymer or the basic polymer has a gelling functional group which is gelled by the organic electrolyte. Examples of the easily gelling functional group include a cyano group and a methoxycarbonyl group. These groups have high solubility in organic electrolytes, and thus easily gel an acidic polymer or a basic polymer. This makes it possible to hold the organic electrolyte in the crosslinked product or polymer composite, and to exhibit high ionic conductivity.

As a specific example of the above acidic polymer, an acidic polymer represented by the following [Chemical Formula 5] can be exemplified. In Chemical Formula 5, the substituent R ₁ is _one of H and CH ₃ , the substituent X ₁ is _one of COOCH _{3 and} CN, which is the easily gelling functional group, and the substituent Y ₁ is the above-mentioned acidic group of either COOH or SO ₃ H, n ₁ is in the range of 100 to 10,000, and n ₂ is 10 to 100
00 range. In particular, in the chemical formula 5, the substituent R ₁ is CH ₃
And the substituent X ₁ (functional group for easily gelling) is COOCH ₃ , the substituent Y ₁ (acidic group) is COOH, and n ₁ is 100
In the range of 10,000, methyl methacrylate and the n ₂ in the range of 10 to 1000 - acrylic acid copolymer is preferably used (hereinafter MMA-AAco). The acidic polymers exemplified above include COOH groups or SO
_It has a plurality of ₃ H groups. If the range of n ₁ and n ₂ indicating the degree of polymerization of the acidic polymer is less than the above range, the fluidity of the polymer electrolyte becomes high and the polymer electrolyte is not solidified. Is not preferable because it becomes too large to be gelled by the organic electrolyte.

[0056]

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The basic compound which crosslinks the acidic polymer includes trimethylolpropane-tri-β-azirid
inylpropionate, tetramethylomethane-tri-β-aziridi
nylpropionate, trimethylopropane-tris (2-methyl-1-a
ziridinepropionate), N, N-hexamethylene-1,6-bis (1-a
ziridinecarboxamide), N, N, N ', N'-tetramethylethylen
ediamine, N, N, N ', N'-tetramethyldiaminomethane, N,
N, N ', N'-tetramethyl-1,3-propanediamine, N, N, N', N'-
tetramethyl-1,4-buthanediamine, N, N, N ', N'-tetramet
hyl-1,6-hexanediamine, N, N, N ', N'-tetramethyl-1,3-b
utanediamine, N, N, N ', N'-tetramethyl-1,4-phenylendi
amines, among which trimethylolprop
ane-tri-β-aziridinylpropionate (hereinafter referred to as TAZM) is preferred. The basic compounds exemplified above each have two or more aziridine rings (ethyleneamine groups) or amino groups exhibiting basicity in the molecule, and are divalent or higher valent bases.

Next, the formation of a crosslinked product by an acidic polymer and a basic compound will be described using MMA-AAco and TAZM as examples. The cross-linking reaction by MMA-AAco and TAZM occurs by one or both of a neutralization reaction with a normal acid-base and a cleavage reaction of an aziridine ring (ethyleneamine group). Examples of the neutralization reaction are shown in the following [Chemical formula 6], and examples of the cleavage reaction are shown in the following [Chemical formula 7].

[0059]

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[0060]

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As shown in the above [Formula 6] and [Formula 7],
TAZM has three aziridine rings having a ring structure containing N (nitrogen atom) in one molecule.
Two aziridine rings function as basic groups. On the other hand, M
MA-AAco has a CH ₃ group and COO in the main chain of polymethylene.
A large number of CH ₃ groups and COOH groups are bonded, and this COOH group functions as an acidic group. Thus, TA
ZM and MMA-AAco have a plurality of basic groups and acidic groups, respectively. When the acidic groups and basic groups react, a crosslinked product having a three-dimensional structure as shown in FIG. 1 is obtained. .

The organic electrolyte is COA of MMA-AAco.
By dissolving the H ₃ groups to gel the MMA-AAco itself, it is retained in the crosslinked product shown in FIG. As such an organic electrolyte, a solution in which a lithium salt is dissolved in an aprotic solvent is preferable. Examples of the aprotic solvent include propylene carbonate, ethylene carbonate, butylene carbonate, benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, dioxolan, 4-methyldioxolan, N, N-dimethylformamide, dimethylacetamide, dimethyl Sulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, ethyl butyl carbonate, dipropyl carbonate, diisopropyl carbonate, dibutyl carbonate , Diethylene glycol, dimethyl Aprotic solvents such as ether, or a mixed solvent obtained by mixing two or more of these solvents. In particular, propylene carbonate, ethylene carbonate, butylene carbonate and dimethyl carbonate, methyl ethyl It is preferable to include at least one of carbonate and diethyl carbonate.

As the lithium salt, LiPF ₆ ,
_{LiBF 4, LiSbF 6, LiAsF 6} , LiClO 4,
LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, LiC ₄ F ₉
SO ₃ , LiSbF ₆ , LiAlO ₄ , LiAlCl ₄ , Li
One or more lithium salts of N (C _x F _{2x + 1} SO ₂ ) (C _y F _{2 y10 1} SO ₂ ) (where x and y are natural numbers), LiCl, LiI, etc. are mixed. In particular, those containing any one of LiPF ₆ and LiBF ₄ are preferable. In addition, a conventionally known nonaqueous electrolyte for a lithium secondary battery can also be used.

The composition ratio of the acidic polymer in the above polymer electrolyte is preferably in the range of 1 to 10% by weight. Also,
The composition ratio of the basic compound is preferably in the range of 1 to 20% by weight. Further, the composition ratio of the organic electrolyte is preferably in the range of 70 to 98% by weight. If the composition ratio of the acidic polymer is less than the above range, the fluidity of the polymer electrolyte becomes high, which is not preferable. On the other hand, if the composition ratio of the basic compound is less than the above range, the fluidity of the polymer electrolyte increases, which is not preferable. If the composition ratio exceeds the above range, the ionic conductivity decreases, which is not preferable. Further, if the composition ratio of the organic electrolyte is less than the above range, the ionic conductivity is lowered, which is not preferable.

Next, the formation of a crosslinked product by a basic polymer and an acidic compound will be described. Examples of the basic polymer according to the present invention include those represented by the following [Chemical Formula 8].
In the chemical formula 8, the substituent R ₂ is one of H and CH ₃ , the substituent X ₂ is one of COOCH _{3 and} CN, which is the easily gelling functional group, and the substituent Y ₂ is C ₅
H ₄ N or SCm ₁ H2m ₁ N (CH ₃ ) ₂ (where 0 ≦ m ₁
≦ 10), wherein n ₃ is 10
In the range of 0 to 10000, n ₄ is in the range of 10 to 1,000. Above exemplified basic polymer, C ₅ H ₄ N group or _{Cm 1 H2m 1 N (CH 3} ) shows a basic has a plurality of ₂ groups. If the range of n ₃ and n ₄ indicating the degree of polymerization of the basic polymer is less than the above range, the flowability of the polymer electrolyte becomes high, which is not preferable. And it is not preferable because it is not gelled by the organic electrolytic solution.

[0066]

Embedded image

Examples of the acidic compound that crosslinks the basic polymer include those represented by any of the following (1) to (6). _{HOOC-Cm 2 H2m 2 -COOH (} 1) HOOC- (CH 2 O) m 3 -COOH (2) HOOC- (C 2 H 4 O) m 3 -COOH (3) HO 3 S-Cm 4 H2m 4 - SO ₃ H (4) HO ₃ S— (CH ₂ O) m ₅ —SO ₃ H (5) HO ₃ S— (C ₂ H ₄ O) m ₅ —SO ₃ H (6) where m ₂ and m ₃ , M ₄ and m ₅ are respectively 0 ≦ m ₂ ≦ 50
1 ≦ m ₃ ≦ 50, 0 ≦ m ₄ ≦ 50, and 1 ≦ m ₅ ≦ 50. The acidic compound exemplified above is a divalent acid having two acidic COOH groups (carboxyl groups) or two SO ₃ H groups (sulfonic acid groups). Incidentally, m ₂ , m ₃ ,
When the range of m ₄ and m ₅ is less than the above range, it is not preferable because a crosslinked body is difficult to be formed, and when the range exceeds the above range, the crosslinked body becomes rigid and is not easily gelled by an organic electrolyte solution. .

The crosslinking reaction with the basic polymer and the acidic compound is based on a neutralization reaction with an acid base. That is, a basic group of either C ₅ H ₄ N or Cm ₁ H 2m ₁ N (CH ₃ ) ₂ and an acidic group of either a COOH group (carboxyl group) or an SO ₃ H group (sulfonic acid group) A crosslinked product is formed by the reaction with the group. Further, the basic polymer and the acidic compound have a plurality of basic groups and acidic groups, respectively, and a two-dimensional or three-dimensional crosslinked product is obtained by reacting these acidic groups and basic groups. .

The organic electrolyte is a basic polymer COOC.
By dissolving the H ₃ group or the CN group and gelling the basic polymer itself, it is retained in the crosslinked product.

The composition ratio of the basic polymer in the polymer electrolyte is preferably in the range of 1 to 15% by weight. Further, the composition ratio of the acidic compound is preferably in the range of 1 to 10% by weight. Further, the composition ratio of the organic electrolyte is preferably in the range of 70 to 98% by weight. If the composition ratio of the basic polymer is less than the above range, the fluidity of the polymer electrolyte is increased, which is not preferable. On the other hand, if the composition ratio of the acidic compound is less than the above range, the fluidity of the polymer electrolyte is undesirably increased, and if the composition ratio exceeds the above range, the ionic conductivity is undesirably reduced. Further, when the composition ratio of the organic electrolyte is less than the above range, the ionic conductivity is lowered, which is not preferable. When the composition ratio exceeds the above range, the fluidity of the polymer electrolyte is increased, which is not preferable.

Next, the formation of a crosslinked product by a basic polymer and an acidic polymer will be described. Examples of the basic polymer include those represented by the above [Chemical Formula 8], and examples of the acidic polymer include those represented by the above [Chemical Formula 5].

The crosslinking reaction with the basic polymer and the acidic polymer is based on a neutralization reaction with an acid base. That is, a basic group of either C ₅ H ₄ N or Cm ₁ H 2m ₁ N (CH ₃ ) ₂ and an acidic group of either a COOH group (carboxyl group) or an SO ₃ H group (sulfonic acid group) Reaction with the group forms a polymer conjugate. Further, the basic polymer and the acidic polymer have a plurality of basic groups and acidic groups, respectively, and the acid group and the basic group react to form a polymer composite having a two-dimensional or three-dimensional structure. Can be

The organic electrolyte is prepared by dissolving the COOCH ₃ group or CN group of the easily gelling functional group contained in the basic polymer or the acidic polymer to gel one or both of the basic polymer and the acidic polymer. By the above, it is retained in the polymer composite.

The composition ratio of the basic polymer in the polymer electrolyte is preferably in the range of 1 to 15% by weight. Further, the composition ratio of the acidic polymer is preferably in the range of 1 to 10% by weight. Further, the composition ratio of the organic electrolyte is preferably in the range of 70 to 98% by weight. When the composition ratio of the basic polymer is less than the above range, the fluidity of the polymer electrolyte is increased, which is not preferable. When the composition ratio exceeds the above range, the ionic conductivity is lowered, which is not preferable. Further, when the composition ratio of the acidic polymer is less than the above range, the fluidity of the polymer electrolyte becomes high, which is not preferable.
It is not preferable because ionic conductivity is lowered. Further, when the composition ratio of the organic electrolyte is less than the above range, the ionic conductivity is decreased, which is not preferable.
It is not preferable because the fluidity of the polymer electrolyte increases.

Further, the polymer electrolyte of the present invention can constitute a lithium secondary battery together with a positive electrode and a negative electrode capable of inserting and extracting lithium. LiMn
₂ O ₄ , LiCoO ₂ , LiNiO ₂ , LiFeO ₂ , V ₂ O
₅ , those containing a positive electrode active material capable of inserting and extracting lithium, such as organic disulfide compounds such as TiS and MoS, and organic polysulfide compounds. As the negative electrode, those capable of reversibly occluding and releasing lithium ions are preferable, and examples thereof include those containing artificial graphite, natural graphite, graphitized carbon fiber, amorphous carbon, and the like. Metallic lithium can also be used as the negative electrode. As specific examples of the positive electrode and the negative electrode, the above-described positive electrode active material or negative electrode active material, a binder and, if necessary, a conductive auxiliary material are mixed, and these are applied to a current collector made of a metal foil or a metal net. To form a sheet. In addition to the above, those which are conventionally known as a positive electrode or a negative electrode of a lithium secondary battery can also be used.

A lithium secondary battery is formed by integrating the above-described polymer electrolyte between the positive electrode and the negative electrode. The polymer electrolyte functions not only as a lithium ion electrolyte but also as a separator for separating the positive electrode and the negative electrode. Further, a conventional separator may be used after being impregnated with a polymer electrolyte.

Next, an example of a method for manufacturing the above-described lithium secondary battery will be described with reference to the drawings. The method for manufacturing a lithium secondary battery of the present invention includes a paste preparation step, a unit cell manufacturing step, and a heat treatment step. First, in a paste preparation step, as shown by reference numeral 1 in FIG. 2, an acidic polymer, a basic compound, and an organic electrolyte are mixed to prepare an electrolyte paste P. The composition of the electrolyte paste is the same as the composition ratio of the polymer electrolyte described above.

Next, in the unit cell forming step, the obtained electrolyte paste P is applied to the positive electrode 10 and the negative electrode is immediately laminated on the applied electrolyte paste (reference numeral 3). Thus, the unit cell 12 is obtained.

Further, as shown by reference numeral 4 in the figure, the obtained unit cell 12 is housed in a metal battery
By performing a heat treatment in a state where the battery container 13 is sealed by the above, the acidic polymer is cross-linked by the basic compound in the electrolyte paste P, and the acidic polymer is gelled by the organic electrolytic solution to obtain a polymer electrolyte E. A lithium secondary battery 15 is obtained. Heat treatment condition is 4
It is preferable that the temperature is in the range of 0 to 85 ° C. for 5 to 600 minutes. If the heat treatment temperature is lower than the above range, the crosslinking reaction may not sufficiently proceed, which is not preferable. If the heat treatment temperature is higher than the above range, the lithium salt in the organic electrolyte may be decomposed, which is not preferable. Similarly, if the heat treatment time is shorter than the above range, the crosslinking reaction may not sufficiently proceed, which is not preferable. If the heat treatment time is longer than the above range, the lithium salt in the organic electrolyte may be decomposed, which is not preferable.

According to the above-described method for manufacturing a lithium secondary battery, the electrolyte paste P is applied to the positive electrode 10, the negative electrode 11 is laminated on the applied electrolyte paste P, and the heat treatment is performed. The polymer electrolyte E can be easily formed by crosslinking the polymer, and the productivity of the lithium secondary battery 15 can be increased. Further, since a polymerization initiator is unnecessary, a reaction product of the polymerization initiator does not remain in the polymer electrolyte and does not adversely affect the charge / discharge reaction.

In the above production method, a basic polymer and an acidic compound may be used instead of the acidic polymer and the basic compound. Alternatively, the positive electrode 10 may be laminated after applying the electrolyte paste P to the negative electrode 11. Furthermore,
The heat treatment may not be performed depending on the combination of the acidic polymer, the basic polymer, the acidic compound, and the basic compound.

Next, another example of the lithium secondary battery of the present invention will be described with reference to the drawings. This method for manufacturing a lithium secondary battery includes an electrode group forming step, a gelling step, and a heat treatment step. First, as shown by reference numeral 6 in FIG. 3, in the electrode group forming step, an acidic polymer 22 is arranged between the positive electrode 20 and the negative electrode 21 to form an electrode group 23, and this electrode group is housed in a battery container 24. The acidic polymer 22 may be impregnated in advance into a nonwoven fabric or the like made of a polyolefin resin and sandwiched between the positive electrode 20 and the negative electrode 21.

Next, in the gelling step, as shown by reference numeral 7 in FIG. 3, a basic compound and an organic electrolytic solution are mixed to prepare a gelling solution G. Then, as shown by reference numeral 8, the gelling solution G is added to the electrode group 23 in the battery container 24. Further, as shown by reference numeral 9 in the figure, the battery container 23 is
By performing heat treatment in this state, the basic polymer 22 is cross-linked by the acidic compound in the gelling solution, and the basic polymer 22 is gelled by the organic electrolytic solution to obtain a polymer electrolyte E. A lithium secondary battery 26 is obtained. The heat treatment is preferably performed at a temperature in the range of 40 to 85 ° C. for 5 to 600 minutes, as in the above-described manufacturing method.

According to the above-described method for manufacturing a lithium secondary battery, the acidic polymer 22 is inserted into the battery container 24 in advance, and a basic compound is added together with the organic electrolyte to crosslink the acidic polymer 22. The polymer electrolyte E can be formed in the battery container 24, and the manufacturing process of the lithium secondary battery can be simplified to increase the productivity. Further, since the polymerization initiator is unnecessary, the reaction product of the polymerization initiator does not remain in the polymer electrolyte and does not adversely affect the charge / discharge reaction, and no gas is generated due to the reaction of the polymerization initiator. .

In the above production method, a basic polymer and an acidic compound may be used instead of the acidic polymer and the basic compound. Further, instead of the combination of the acidic polymer and the basic compound, a combination of the acidic polymer and the basic polymer may be used. Further, acidic polymers,
Depending on the combination of the basic polymer, the acidic compound and the basic compound, the heat treatment may not be performed.

[0086]

EXAMPLES (Experimental Example 1) Various polymer electrolytes were prepared, and the appearance and ionic conductivity of the polymer electrolyte were measured. Weight average molecular weight Mw is 34000, number average molecular weight Mn
Was dissolved in an organic electrolyte solution of MMA-AAco (acidic polymer), and TAZM (basic compound) was further added to prepare an electrolyte paste. This electrolyte paste was heat-treated at 80 ° C. for 10 minutes as needed. Thus, the polymer electrolytes of Experimental Examples 1 to 10 shown in Table 1 were prepared by crosslinking MMA-AAco with TAZM and gelling MMA-AAco with the organic electrolyte. Organic electrolyte is EC + DMC
1M LiBF ₄ dissolved in (1 + 1) mixed solvent (organic electrolyte 1), 1M LiBF ₄ dissolved in DMC (organic electrolyte 2) and EC + DMC (1 + 1) )
Was used (organic electrolyte solution 3). EC and DM
C was mixed at a volume ratio of 1: 1. EC is an abbreviation for ethylene carbonate, and DMC is an abbreviation for dimethyl carbonate.

The obtained polymer electrolyte was made
A 1-mm-thick disk was cut out, and the cut-out polymer electrolyte was sandwiched between two metallic lithium foils having a diameter of 16 mm and a thickness of 0.5 mm to form a single cell. For this single cell, the ionic conductivity of lithium in the polymer electrolyte was measured by the AC impedance method. Table 1 shows the results. Table 1 also shows the observation results of the appearance of the prepared polymer electrolyte. The above operations were all performed in air at a dew point of −40 ° C. or less. Also, during the preparation of all polymer electrolytes,
No gas generation was observed.

[0088]

[Table 1]

As shown in Table 1, Examples 1 and 2
The sample No. 1 was in a semi-solid gel state only by mixing and allowing MMA-AAco, the organic electrolyte and TAZM to stand.
When these ionic conductivities were measured, they were 3 to 3.5 m.
It showed an ion conductivity of S / cm, and it was confirmed that it had sufficient ion conductivity as an electrolyte of a lithium secondary battery. Next, about Example 3, similarly to Example 1 and Example 2, MMA-AAco, organic electrolyte solution, and TAZ
M was mixed and allowed to stand, resulting in a semi-solid gel state. The ionic conductivity also showed 3.2 mS / cm, confirming that the lithium secondary battery had sufficient ionic conductivity as an electrolyte.

Next, in Examples 4 and 5, MMA
-Even when heat treatment was performed by mixing AAco, the organic electrolyte solution and TAZM, the gel did not gel and the appearance remained liquid. This is because, in Example 4, the amount of TAZM was MMA-AAco.
It is considered that the crosslinking was not sufficiently performed because the amount was too small, and gelation did not proceed. Example 5
It is considered that the amount of TAZM was too small with respect to the amount of MMA-AAco, so that crosslinking was not sufficiently performed, and that the amount of organic electrolyte was excessive, so that MMA-AAco remained dissolved. Can be The ionic conductivity was not measured because the appearance was liquid.

Next, in Example 6, MMA-AAc
o, the gelation did not progress only by mixing the organic electrolyte and TAZM, and the heat treatment finally resulted in a semi-solid gel state. This is different from the experimental example 3 in that TA
It is considered that the heat treatment was required to advance the crosslinking reaction because the ZM amount was slightly small. However, the ion conductivity showed a relatively high value of 3.3 mS / cm, and it was confirmed that the lithium secondary battery had sufficient ion conductivity as an electrolyte. next,
About Example 7, similarly to Example 1 and Example 2,
A mixture of MMA-AAco, an organic electrolyte and TAZM was left alone to form a semi-solid gel. Although the ionic conductivity was slightly lower at 2.4 mS / cm, it was confirmed that the lithium secondary battery had sufficient ionic conductivity as an electrolyte.

Example 8 differs from Example 3 only in that the type of the organic electrolyte is changed, and uses the organic electrolyte 2 to which EC is not added. For Example 8, MMA-AAco, organic electrolyte and TA
The solid state was obtained only by mixing ZM, and did not reach a good gel state. In some cases, only the organic electrolyte was separated without solidification. Therefore, in order to obtain a good gel state, the composition of the organic electrolyte is also an important factor,
It is considered necessary to include at least EC. The ionic conductivity was not measured because the appearance was solid.

In Examples 9 and 10, only the type of the organic electrolyte was changed with respect to the mixing ratio of Examples 1 and 2, and the organic electrolyte 3 in which LiBF ₄ was not dissolved was used. is there. For Examples 9 and 10, the MM
Even when A-AAco, the organic electrolyte solution and TAZM were mixed and heat-treated, the gel did not gel and the appearance remained liquid. Therefore, it is considered that LiBF ₄ , that is, a lithium salt must be contained in order to obtain a good gel state. The ionic conductivity was not measured because the appearance was liquid.

From the above, it was found that all the polymer electrolytes in which a good gel state was obtained show a good ionic conductivity of 3 mS / cm or more. Also,
In order to obtain a good gel state, it is necessary to optimize the mixing ratio of the acidic polymer, the basic compound and the organic electrolyte,
It was also found that EC and LiBF ₄ were necessary for the composition of the organic electrolyte. PC instead of EC
(Propylene) carbonate) and using LiPF ₆ instead of LiBF ₄ , the same results as above were obtained.

(Experimental Example 2) Next, a polymer electrolyte was prepared from a basic polymer, an acidic polymer and an organic electrolyte, and the appearance and ionic conductivity of the polymer electrolyte were measured. First, 9 g of methyl methacrylate and 1 g of 4-vinylpyridine and 5 mg of a polymerization initiator AIBN are put into 50 ml of methyl ethyl ketone in a reaction vessel and dissolved therein. did. Next, the reaction was carried out by heating at 60 ° C. for 4 hours in a nitrogen atmosphere, dry methanol was added dropwise to remove unreacted substances and the polymerization initiator, and vacuum drying was performed at 100 ° C. to obtain methyl methacrylate. A 4-vinylpyridine copolymer (basic polymer) was prepared. The weight average molecular weight Mw of this copolymer was 34,000.

10 parts by weight of the above basic polymer was added to 90 parts
Solution A was dissolved in parts by weight of an organic electrolyte solution. Further, the weight average molecular weight Mw is 34,000, and the number average molecular weight Mn is 150.
10 parts by weight of MMA-AAco (acidic polymer)
Solution B was dissolved in 0 parts by weight of an organic electrolyte solution. A above
The solution and the solution B were mixed and heat-treated at 80 ° C. for 10 minutes to obtain a polymer electrolyte of Example 11.

A polymer electrolyte of Example 12 was obtained in the same manner as in Example 11 except that 9.5 g of methyl methacrylate and 0.5 g of 4-vinylpyridine were used. As the organic electrolyte, a solution obtained by dissolving 1M LiBF ₄ in a mixed solvent of EC + DMC (1 + 1) was used.

For the obtained polymer electrolyte, the ionic conductivity of lithium was measured in the same manner as in Experimental Example 1. In addition, regarding the appearance, both polymer electrolytes were in a semi-solid gel state. Table 2 shows the results.

[0099]

As is clear from Table 2, it is understood that the polymer electrolytes of Examples 11 and 12 show good ionic conductivity.

(Experimental Example 3) Physical gels and chemical gels, which are conventional polymer electrolytes, were prepared, and a comparative test was conducted between these polymer electrolytes and the polymer electrolyte of the present invention. First, 90 parts by weight of an organic electrolyte solution was added to 10 parts by weight of polyvinylidene fluoride and heated to 100 ° C. to dissolve polyvinylidene fluoride. By cooling this, a polymer electrolyte (physical gel) of Comparative Example 1 was obtained.
The ionic conductivity of this polymer electrolyte is 3.0 mS / cm
Met.

Also, 95 parts by weight of an organic electrolyte solution is added to 5 parts by weight of PEGDMA (polyethylene glycol dimethyl acrylate), and a small amount of a polymerization initiator AIBN is further added, followed by reaction at 60 ° C. for 24 hours in a nitrogen atmosphere. As a result, a polymer electrolyte (chemical gel) of Comparative Example 2 was obtained. The ionic conductivity of this polymer electrolyte is 2.5 mS /
cm.

(Comparative Test) A storage test was performed by storing the polymer electrolytes of Examples 1 and 2 and the polymer electrolytes of Comparative Examples 1 and 2 at 60 ° C. for 24 hours. As a result, the polymer electrolytes of Examples 1 and 2 and Comparative Example 2 showed no particular change after storage. On the other hand, the polymer electrolyte of Comparative Example 1, which was a physical gel, was dissolved and changed to a liquid state by high-temperature storage.

Next, as for the polymer electrolyte of Comparative Example 2, ten samples were prepared. Among them, three samples did not completely progress to gelation. These three are considered to be due to oxygen being mixed during the polymerization reaction. Therefore, for a chemical gel, it is necessary to strictly control the atmosphere during production. Regarding the remaining seven samples in which gelation had progressed, nitrogen gas was generated by the decomposition of AIBN during the polymerization reaction.

As described above, the polymer electrolyte of the present invention has higher stability at high temperatures than conventional physical gels, has a low yield unlike chemical gels, and generates gas during crosslinking. It is clear that no problem occurs.
Therefore, it was found that the polymer electrolyte of the present invention can be suitably used for an electrolyte of a lithium secondary battery.

[0106]

As described above in detail, according to the polymer electrolyte of the present invention, the organic electrolyte is held in the crosslinked product or the polymer composite, and the polymer is gelled by the organic electrolyte. In addition, the polymer and the compound or the polymers can hold the organic electrolyte without being dissociated, and a polymer electrolyte having excellent heat resistance can be formed. In addition, since the polymer has a structure in which the compound is crosslinked, or the polymers are crosslinked, the crosslinked structure is not broken at a high temperature. Further, since the cross-linking is a compound of an acid-base, the reaction rate is extremely high, the cross-linking structure is formed evenly, and there is no possibility that the cross-linking becomes insufficient.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a crosslinked structure of a polymer electrolyte according to an embodiment of the present invention.

FIG. 2 is a process chart illustrating a method for producing a polymer electrolyte according to an embodiment of the present invention.

FIG. 3 is a process diagram illustrating a method for producing a polymer electrolyte according to an embodiment of the present invention.

Continued on the front page F-term (reference) 4J002 BB20Y BG01W BG04W BG04X BG06W BG06X BG07X BG10W BG10X BG11W BG11X BQ00W CH05Y ED036 EF066 EN036 EU016 EV236 GQ02 5H029 AJ00 AM07 AL02 A0312 CJ06 CJ08 CJ11 CJ13 CJ22 DJ04 DJ09 EJ12 HJ00 HJ02 HJ11 HJ14

Claims (21)

[Claims] 1. An acidic polymer having a plurality of acidic groups, at least a divalent or higher valent basic compound which crosslinks the acidic polymer by reacting with the acidic group, and a lithium salt dissolved in an aprotic solvent. And the organic polymer is held by the crosslinked body while the acidic polymer is crosslinked by the basic compound to form a crosslinked body, and at least the acidic polymer is A polymer electrolyte, which is gelled by an organic electrolyte. 2. A basic polymer having a plurality of basic groups and at least a divalent or higher valent acidic compound which cross-links the base main chain polymer by reacting with the basic.
An organic electrolyte solution in which a lithium salt is dissolved in an aprotic solvent, wherein the basic polymer is crosslinked by the acidic compound to form a crosslinked body, and the organic electrolyte solution is the crosslinked body. , And at least the basic polymer is gelled by the organic electrolytic solution. 3. It comprises at least a basic polymer having a plurality of basic groups, an acidic polymer having a plurality of acidic groups, and an organic electrolyte obtained by dissolving a lithium salt in an aprotic solvent, A polymer complex is formed by the combination of the basic group of the basic polymer and the acidic group of the acidic polymer, and the organic electrolytic solution is retained by the polymer composite, and the basic polymer or the acidic polymer is retained. A polymer electrolyte, wherein one or both of the polymers are gelled by the organic electrolyte. 4. The polymer electrolyte according to claim 1, wherein the acidic group contained in the acidic polymer is one of a carboxyl group and a sulfonic acid group. 5. The polymer electrolyte according to claim 2, wherein the basic group of the basic polymer is one of a pyridyl group and a dimethylamino group. 6. The method according to claim 1, wherein the acidic polymer or the basic polymer has a gelling functional group which is gelled by the organic electrolyte. A polymer electrolyte as described in the above. 7. The polymer electrolyte according to claim 6, wherein the easily gelling functional group is one of a cyano group and a methoxycarbonyl group. 8. The method according to claim 1, wherein the acidic polymer is represented by the following chemical formula 1.
8. The polymer electrolyte according to any one of 4, 6, and 7. Embedded image However, the substituent R ₁ is _one of H and CH ₃ , and the substituent X ₁ is the above-mentioned gelling functional group and has COOC
H ₃ or CN, the substituent Y ₁ is the above-mentioned acidic group and is either COOH or SO ₃ H, n ₁ is in the range of 100 to 10,000, and n ₂ is 10 to 10. It is in the range of 1000. 9. The basic polymer is represented by the following [Chemical Formula 2]
4. The method according to claim 2, wherein:
The polymer electrolyte according to any one of 5, 6, and 7. Embedded imageProvided that the substituent R_TwoIs H or CH_ThreeOne of
Substituent X_TwoIs the above-mentioned easily gelling functional group and COOC
H_ThreeOr CN, and the substituent Y_TwoIs
A basic group,_FiveH_FourN or Cm₁H2m₁N (CH_Three)
_Two(However, 0 ≦ m₁≦ 10), and n_Three
Is in the range of 100 to 10000, and n _FourIs 10 to 10
00 range. 10. The method according to claim 1, wherein the acidic compound is selected from the group consisting of:
The polymer electrolyte according to claim 1, wherein the polymer electrolyte is represented by any one of the above (6). _{HOOC-Cm 2 H2m 2 -COOH (} 1) HOOC- (CH 2 O) m 3 -COOH (2) HOOC- (C 2 H 4 O) m 3 -COOH (3) HO 3 S-Cm 4 H2m 4 - SO ₃ H (4) HO ₃ S— (CH ₂ O) m ₅ —SO ₃ H (5) HO ₃ S— (C ₂ H ₄ O) m ₅ —SO ₃ H (6) where m ₂ and m ₃ , M ₄ and m ₅ are respectively 0 ≦ m ₂ ≦ 50
1 ≦ m ₃ ≦ 50, 0 ≦ m ₄ ≦ 50, and 1 ≦ m ₅ ≦ 50. 11. The method according to claim 11, wherein the basic compound is trimethylolpr
opane-tri-β-aziridinylpropionate, tetramethylomet
hane-tri-β-aziridinylpropionate, trimethylopropan
e-tris (2-methyl-1-aziridinepropionate), N, N-hexame
thylene-1,6-bis (1-aziridinecarboxamide), N, N, N ', N'
-tetramethylethylenediamine, N, N, N ', N'-tetramethyl
diaminomethane, N, N, N ', N'-tetramethyl-1,3-propaned
iamine, N, N, N ', N'-tetramethyl-1,4-buthanediamine,
N, N, N ', N'-tetramethyl-1,6-hexanediamine, N, N, N', N '
-tetramethyl-1,3-butanediamine, N, N, N ', N'-tetramet
The polymer electrolyte according to claim 2, wherein the polymer electrolyte is any one of hyl-1,4-phenylendiamine. 12. A lithium secondary battery comprising: the polymer electrolyte according to claim 1; and a positive electrode and a negative electrode capable of inserting and extracting lithium. . 13. A method for producing a lithium secondary battery, comprising: a polymer electrolyte; a sheet-like positive electrode and a negative electrode capable of inserting and extracting lithium; and an acidic polymer having a plurality of acidic groups. A paste for mixing an at least divalent basic compound which crosslinks the acidic polymer by reacting with the acidic group, and an organic electrolyte obtained by dissolving a lithium salt in an aprotic solvent to obtain an electrolyte paste A preparing step, a unit cell in which the electrolyte paste is applied to one or both of the positive electrode and the negative electrode, and the other of the positive electrode and the negative electrode is stacked on the applied electrolyte paste to form a unit cell And a method of manufacturing a lithium secondary battery. 14. A method for producing a lithium secondary battery comprising a polymer electrolyte, a sheet-like positive electrode and a negative electrode capable of inserting and extracting lithium, wherein the method comprises the steps of: A polymer, at least a divalent or higher valent acidic compound that crosslinks the basic polymer by reacting with the basic group, and an organic electrolyte obtained by dissolving a lithium salt in an aprotic solvent to form an electrolyte paste A paste preparation step of obtaining the above, applying the electrolyte paste to one or both of the positive electrode and the negative electrode, and laminating either the other of the positive electrode or the negative electrode on the applied electrolyte paste and a unit cell. A method for manufacturing a lithium secondary battery, comprising: 15. A method for producing a lithium secondary battery comprising a polymer electrolyte, a sheet-like positive electrode and a negative electrode capable of inserting and extracting lithium, wherein the method comprises the steps of: A paste preparation step of mixing a polymer, an acidic polymer having a plurality of acidic groups, and an organic electrolyte obtained by dissolving a lithium salt in an aprotic solvent to obtain an electrolyte paste; and A unit cell manufacturing step of coating the electrolyte paste after application to one or both of the negative electrodes, and laminating the other of the positive electrode or the negative electrode on the electrolyte paste to form a unit cell. Of manufacturing a rechargeable lithium battery. 16. The method according to claim 13, further comprising a heating step of heating the unit cell at a temperature of 40 to 85 ° C. for 10 to 600 minutes after the unit cell manufacturing step. 16. The method for producing a lithium secondary battery according to item 15. 17. A lithium secondary battery comprising: a polymer electrolyte; a sheet-like positive electrode and a negative electrode capable of inserting and extracting lithium; and a battery container containing the polymer electrolyte, the positive electrode, and the negative electrode. A method for manufacturing a battery, comprising: an electrode group including at least an acidic polymer having a plurality of acidic groups between the positive electrode and the negative electrode; and an electrode group manufacturing step of further housing the electrode group in the battery container. A gelling solution is prepared by mixing at least a divalent or more basic compound that crosslinks the acidic polymer and an organic electrolyte obtained by dissolving a lithium salt in an aprotic solvent. A method for producing a lithium secondary battery, comprising: a gelation step of adding the electrode group to an electrode group in a container. 18. A lithium secondary battery comprising: a polymer electrolyte; a sheet-like positive electrode and a negative electrode capable of inserting and extracting lithium; and a battery container containing the polymer electrolyte, the positive electrode, and the negative electrode. A method for manufacturing a battery, comprising: an electrode group including at least a basic polymer having a plurality of basic groups interposed between the positive electrode and the negative electrode to form an electrode group, and further including the electrode group in the battery container. And at least a divalent or more acidic compound that crosslinks the basic polymer, and an organic electrolyte obtained by dissolving a lithium salt in an aprotic solvent to prepare a gelling solution, and the gelling solution is And a gelling step of adding the electrode group to the electrode group in the battery container. 19. A lithium secondary battery comprising: a polymer electrolyte; a sheet-like positive electrode and a negative electrode capable of inserting and extracting lithium; and a battery container containing the polymer electrolyte, the positive electrode, and the negative electrode. A method of manufacturing a battery, comprising: an electrode group including at least an acidic polymer having a plurality of acidic groups between the positive electrode and the negative electrode; and an electrode group manufacturing step of further housing the electrode group in the battery container. A gelling solution is prepared by mixing a basic polymer having a plurality of basic groups and an organic electrolytic solution in which a lithium salt is dissolved in an aprotic solvent, and the gelling solution is used as an electrode in the battery container. A method for producing a lithium secondary battery, comprising: a gelling step of adding to a group. 20. A lithium secondary battery comprising: a polymer electrolyte; a sheet-like positive electrode and a negative electrode capable of inserting and extracting lithium; and a battery container containing the polymer electrolyte, the positive electrode, and the negative electrode. A method of manufacturing a battery, wherein an electrode group is formed by sandwiching at least a basic polymer having a plurality of basic groups between the positive electrode and the negative electrode, and further including an electrode group in the battery container. And an acidic polymer having a plurality of acidic groups, and an organic electrolyte obtained by dissolving a lithium salt in an aprotic solvent to prepare a gelling solution, and using the gelling solution as an electrode in the battery container. A method for producing a lithium secondary battery, comprising: a gelling step of adding to a group. 21. After the gelling step, 40-85 ° C.
21. The method for producing a lithium secondary battery according to claim 17, further comprising a heating step of heating under a condition of 10 to 600 minutes in the range described above.