JP3312619B2 - Thin secondary battery and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin secondary battery which has a high output and can operate stably at a low temperature, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In today's market where portable information terminals such as notebook personal computers and mobile phones are rapidly expanding, batteries used in portable information terminals have high output and are excellent in safety. It is especially required. In order to meet this demand, development of secondary batteries using an alkali metal ion such as lithium ion as a charge carrier and utilizing an electrochemical reaction accompanying the transfer of charge has been actively performed. Non-aqueous electrolyte solutions that contribute to high output can be used for secondary batteries using such alkali metal ions,
In order to ensure safety, it is necessary to suppress outflow and evaporation of the electrolyte solution.

[0003] In order to suppress the outflow and evaporation of the electrolyte solution, studies have been made to use a polymer gel electrolyte having a low solvent content instead of a non-aqueous electrolyte solution. For example, JP-B-61-23947 discloses a polymer such as polyvinylidene fluoride and a group I or
A polymer gel electrolyte comprising a Group II metal salt and an organic solvent having excellent solubility in both is disclosed. U.S. Pat. No. 5,296,318 discloses a polymer gel electrolyte in which a copolymer film of hexafluoropropylene and vinylidene fluoride is impregnated with a solution comprising an organic solvent containing a lithium salt.

Further, a polymer gel electrolyte using a crosslinked polymer of a polymer having a polyether segment has been studied. For example, JP-A-5-109310 discloses a polymer gel electrolyte having a crosslinkable polyether segment. And a mixture in which the alkali metal salt and a solution capable of dissolving the alkali metal salt are mixed, and the molded body is irradiated with light, radiation, or the like to form a cross-link. Are disclosed. In addition, polymer gel electrolytes combining two or more polymers have been studied. For example, JP-A-58-75779
In the publication, polyvinylidene fluoride, polymethyl methacrylate, at least one polymer selected from other specific polymers, a lithium salt, a specific organic solvent,
A battery composed of a metal lithium anode and a cathode made of a specific inorganic compound is disclosed.

[0005]

However, the above-mentioned JP-B-61-23947 and U.S. Pat.
8, JP-A-5-109310 and JP-A-58-310310.
The thin secondary battery using a polymer gel electrolyte having a small solvent content disclosed in Japanese Patent No. 75779 has the following problem.

A polymer gel electrolyte containing a small amount of a solvent has little deformation such as swelling or bending, and can suppress the outflow and evaporation of the electrolyte, which leads to a decrease in output. On the other hand, the ionic conductivity is insufficient as it is. However, there is a problem that a thin secondary battery that operates stably at high output and low temperature cannot be obtained. Also, with the progress of portable information terminals in the future, it is expected that expectations for small and high-output thin secondary batteries will be further increased.

The present invention has been made in view of the above-mentioned problems in the prior art, and has as its object to provide a thin secondary battery which has a high output and can operate stably at a low temperature, and a method of manufacturing the same. Make it an issue.

[0008]

Means for Solving the Problems The first invention of the present application for solving the above problems is to impregnate a power generating element comprising a positive electrode, a negative electrode and a separator with a monomer or oligomer capable of forming a polymer gel, and In the method for manufacturing a thin secondary battery to be packaged, a step of gelling a monomer or an oligomer impregnated in a power generation element by a chemical reaction, and a step of charging or discharging while applying pressure to the power generation element impregnated with the monomer or the oligomer, Gelling of the monomer by charging or discharging
Or before or after the step of gelling the oligomer
Step of gelling monomer or oligomer by reaction
This is a method for producing a thin secondary battery.

Therefore, according to the method of manufacturing the thin secondary battery of the first invention of the present application, since the monomer or oligomer is gelled by charging or discharging, the ionic conduction of the gel electrolyte gelled by the electric current based on charging or discharging. Anisotropy occurs in degrees. Thereby, the ionic conductivity of the gel electrolyte in a specific direction, that is, the direction connecting the positive electrode and the negative electrode, is increased. As a result, since a gel electrolyte having high ionic conductivity is formed even in minute gaps between the electrode active materials, there is an advantage that a high output and stable operation can be performed at a low temperature. In addition, monomer or ori
The step of gelling the sesame is carried out by charging or discharging.
Before or after the step of gelling the oligomer or oligomer
You can also .

The second invention of the present application is the method of manufacturing a thin secondary battery according to the first invention of the present application, wherein the chemical reaction is started by heating.

Therefore, according to the method for manufacturing a thin secondary battery of the second invention of the present application, there are advantages of the first invention of the present application, and a chemical reaction is started by heating, so that the thin secondary battery can be easily prepared. Can be manufactured.

Further, the third invention of the present application provides the method wherein the monomer or the oligomer comprises (a) an unsaturated carboxylic acid compound,
(b) at least one compound of a polyene compound and a polythiol compound, (c) an organosiloxane compound, and (d) a vinyl compound having an amide group, at least one compound of the compound group consisting of: A method for manufacturing a thin secondary battery according to the first invention or the second invention of the present application, characterized by including the following.

Therefore, according to the method for manufacturing a thin secondary battery of the third invention of the present application, the gel electrolyte having higher ionic conductivity as well as the advantages of the first invention of the present application or the second invention of the present application is obtained. Since it is formed even in the minute gaps of the electrode active material, there is an advantage that the output can be further increased and the operation can be performed more stably at a low temperature.

Further, the fourth invention of the present application is any one of the first invention to the third invention of the present invention, characterized in that the pressure is applied to the power generating element via an elastic body. A method for manufacturing a thin secondary battery according to any one of the first to third aspects.

Therefore, according to the method for manufacturing a thin secondary battery of the fourth invention of the present application, there is an advantage of any one of the first to third inventions of the present application, and the elastic body is made of Since pressure is applied to the power generating element through the intermediary, there is an advantage that a thin secondary battery can be easily manufactured.

According to a fifth invention of the present application, the positive electrode and the negative electrode are wound flat through the separator, and the invention is characterized in that the positive electrode and the negative electrode are wound flat. It is a manufacturing method of the thin secondary battery as described in any one of the above.

Therefore, according to the thin secondary battery of the fifth invention of the present application and the method of manufacturing the same, the advantages of any one of the first invention to the fourth invention of the present application are obtained, and furthermore, the height is further improved. It has the advantage of being output.

Further, the sixth invention of the present application is directed to a thin secondary battery comprising a power generating element comprising a positive electrode, a negative electrode and a separator and a polymer gel electrolyte in which a monomer or oligomer is gelled. Is a thin secondary battery which is performed by charging or discharging while applying pressure to a chemical reaction and a power generation element.

[0019] The seventh invention of the present application is also characterized in that the monomer or the oligomer is (a) an unsaturated carboxylic acid compound,
(b) at least one compound of a polyene compound and a polythiol compound, (c) an organosiloxane compound, and (d) a vinyl compound having an amide group, at least one compound of the compound group consisting of: A thin secondary battery according to a sixth invention of the present application, characterized in that:

Therefore, according to the thin secondary battery of the sixth invention or the seventh invention of the present application, since the monomer or oligomer is gelled by charging or discharging, it is gelated by the current based on charging or discharging. Anisotropy occurs in the ionic conductivity of the gel electrolyte. Thereby, the ionic conductivity of the gel electrolyte in a specific direction, that is, the direction connecting the positive electrode and the negative electrode, is increased. As a result, since a gel electrolyte having high ionic conductivity is formed even in minute gaps between the electrode active materials, there is an advantage that a high output and stable operation can be performed at a low temperature.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment) A thin secondary battery according to an embodiment of the present invention and a method for manufacturing the same will be described below with reference to FIG. FIG. 1 is a sectional view showing a configuration of a thin secondary battery according to an embodiment of the present invention.

Referring to FIG. 1, a thin secondary battery according to an embodiment of the present invention comprises a positive electrode (a positive electrode current collector 4, a positive electrode active material layer 2) and a negative electrode (a negative electrode current collector 5, a negative electrode active material layer). 3) A power generating element comprising a separator (not shown) and a polymer gel electrolyte 1 in which a monomer or oligomer is gelled are covered with sealing materials 6a and 6b.

[Positive Electrode] The positive electrode 4 according to the embodiment of the present invention
Absorbs positive ions or emits negative ions when charged
Is not particularly limited as long as (i) LiMnO₂, L
iMn₂O ₄, LiCoO₂, LiNiO₂Metal acids such as
(Ii) high conductivity of polyacetylene, polyaniline, etc.
A molecule, (iii) a general formula (R-Sm) n (R is an aliphatic group,
Or aromatic, S is sulfur, and m and n are m ≧
1, n ≧ 1).
(Dithioglycol, 2,5-dimercapto-1,
3,4-thiadiazole, S-triazine-2,4,6
-Trithiol, etc.)
Known ones can be used.

Also, the positive electrode 4 can be formed by mixing the positive electrode active material 2 with an appropriate binder or a functional material. These binders include halogen-containing polymers such as polyvinylidene fluoride, and the functional materials include conductive polymers such as acetylene black, polypyrrole, and polyaniline, which secure electron conductivity, and ion conductivity. And a composite thereof.

[Negative Electrode] The negative electrode 5 is not particularly limited as long as it can absorb and release cations. Crystalline carbon such as graphitized carbon obtained by heat-treating natural graphite, coal or petroleum pitch at a high temperature is used. Conventionally known negative electrode active materials 3 for secondary batteries, such as amorphous carbon obtained by heat-treating coal, petroleum pitch coke, and acetylene pitch coke, and lithium alloys such as lithium metal and AlLi can be used.

[Power Generation Element] The form of the power generation element of the embodiment of the present invention is not particularly limited.
A stack of more than one set, a roll of a long one, and a flat roll are used. Here, from the viewpoint of high output, it is preferable to use a flat winding.

[Monomer or Oligomer] The monomer or oligomer according to the embodiment of the present invention can be gelled by a chemical reaction. For example, it is a monomer that gels by a chemical reaction such as polycondensation reaction, radical polymerization, radiation polymerization, photopolymerization, or plasma polymerization. Further, it is an oligomer that gels by a chemical reaction such as crosslinking between the oligomer and a functional group, radiation crosslinking, or photocrosslinking. Thus, hydrogen bonding,
It is distinguished from those that form a gel by a reaction that does not involve a chemical reaction such as ionic bonding or molecular chain entanglement.

In the present invention, the chemical reaction used for gelation is not particularly limited as long as it forms a chemical bond. Here, from the viewpoint of easy implementation of the invention, it is particularly preferable that the chemical reaction is started by heating such as polycondensation reaction, radical polymerization, crosslinking of oligomer and functional group. In addition, monomers or oligomers that can be gelled by a chemical reaction are:
(a) an unsaturated carboxylic acid compound, (b) a compound comprising at least one of a polyene compound and a polythiol compound, (c) an organosiloxane compound, and (d) a vinyl compound having an amide group. Those containing at least one compound from the group are preferred.

(A) The unsaturated carboxylic acid compound is various acrylate compounds or methacrylate compounds,
For example, methyl (meth) acrylate, butyl (meth)
Alkyl (meth) acrylates such as acrylate and trifluoroethyl (meth) acrylate; alicyclic (meth) acrylates such as tetrahydrofurfuryl (meth) acrylate; hydroxyalkyl (meth) such as hydroxyethyl acrylate and hydroxypropyl acrylate
Acrylate, hydroxypolyoxyethylene (meth)
Acrylates, hydroxypolyoxyalkylene (meth) acrylates such as hydroxypolyoxypropylene (meth) acrylate, methoxyethyl acrylate,
Examples include alkoxy (meth) acrylates such as ethoxyethyl acrylate and phenoxyethyl acrylate, and polyfunctional (meth) acrylates such as trimethylolpropane tri (meth) acrylate, pentaerythritol penta (meth) acrylate, and dipentaerythritol hexa (meth) acrylate. Can be

(B) The polyene compound is, for example, a polyallyl ether compound obtained by adding an epoxy compound such as ethylene oxide, propylene oxide, or allyl glycidyl ether to allyl alcohol, or a polyallyl compound obtained from a polyallyl ether compound and various carboxylic acids. And polyallyl ester compounds. Examples of the (b) polythiol compound include aliphatic, alicyclic and aromatic polythiol compounds such as methane (di) thiol and ethane (di) thiol, 2-mercaptoacetic acid,
Mercaptocarboxylic acid esters such as an esterification reaction product of mercaptopropionic acid and a polyhydric alcohol are exemplified.

(C) As the organosiloxane compound,
For example, hexamethyldisiloxane, hexaphenyldisiloxane, polymethacryloxypropylsiloxane, polymethyl (methacryloxy) siloxane, etc., and a siloxane structure in the skeleton and having an alkyl group, an aryl group, an alkoxy group, a perfluoroalkyl group, etc. Various compounds.

(D) Examples of the vinyl compound having an amide group include (di) butyl (meth) acrylamide,
(Di) dodecyl (meth) acrylamide, (di) stearyl (meth) acrylamide, (di) butylphenyl (meth) acrylamide, (di) octylphenyl (meth) acrylamide and the like.

[Initiator, Crosslinking Agent] In the present invention, a monomer or oligomer which can be gelled by a chemical reaction is impregnated into a power generating element. At this time, an initiator which causes a chemical reaction to each monomer or oligomer may be used if necessary. And a crosslinking agent. These initiators and crosslinking agents are not particularly limited, but are generally azobisisobutyronitrile, benzoyl peroxide, lauroyl peroxide, ethyl methyl ketone peroxide and the like, carbonyl compounds, dimethylaniline, cobalt naphthenate,
Benzoin compounds such as sulfinic acid, mercaptan, benzoin methyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; sulfur compounds such as diacetyl, acetophenone, benzophenone, diphenyl sulfide and dithiocarbamate; and polycondensed ring hydrocarbons such as α-chloromethylnaphthalene Halides of
Metal salts such as iron chloride and silver chloride, p-methoxybenzenediazonium and hexafluorophosphate, onium salts such as triphenylsulfonium,
They can be used alone or as a mixture of two or more.

[Gel which does not itself cause a chemical reaction] A gel which does not itself cause a chemical reaction can be partially added to a power generating element impregnated with a monomer or oligomer which can be gelled by a chemical reaction. Examples of such a gel include fluorinated polyolefins such as polyvinylidene fluoride and polyhexafluoropropylene, polyethers such as polyethylene oxide and polypropylene oxide, and polyacrylonitrile.

[Solvent] In the present invention, the method of introducing a monomer or oligomer capable of forming a polymer gel into the power generating element is not particularly limited, but generally, it is carried out by dissolving in a suitable solvent. Examples of such a solvent include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, N, N′-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, m-cresol and the like. A highly polar basic solvent that can be used as an electrolyte for a secondary battery is advantageous. In the present invention, these basic solvents can be used alone or in combination. In the present invention, the concentration of the monomer or oligomer capable of forming a polymer gel is not particularly limited, and is generally 1 wt. % Or more, 90 wt.
%.

[Electrolyte salt] In the present invention, a monomer or oligo
Solution as a secondary battery electrolyte salt
Known materials can be dissolved and used. these
Examples of the electrolyte salt include, for example, Al, Li, K, and Na.
Potassium metal cation and ClO₄ ⁻, BF ₄ ⁻, P
F₆ ⁻, CF₃SO₃ ⁻, (CF₃SO₂)₂N⁻,
(C₂F₅SO₂)₂N⁻, (CF₃SO₂)₃C⁻,
(C₂F₅SO₂)₃C⁻Of compounds containing halogen such as
Salts composed of anions are exemplified. In the present invention, these
Electrolyte salts may be used alone or in combination.
Can be.

[Additives] In the present invention, if necessary,
Additives such as a heat stabilizer and a viscosity modifier can be added to the solution in which the monomer or oligomer is dissolved.

[Gelling Step] In the present invention, after a power generation element is impregnated with a monomer or oligomer capable of forming a polymer gel by a chemical reaction, pressure is applied to the power generation element. The method is not particularly limited. In addition, the power generating element can be sandwiched between two flat plates or subjected to hydrostatic pressure. Here, from the viewpoint of easiness of implementation, a method of applying pressure by sandwiching the power generating element with an elastic body between two flat plates is particularly preferable. In the production method of the present invention, a chemical reaction of a monomer or an oligomer capable of forming a polymer gel is performed by charging or discharging while applying pressure, but the method of charging or discharging is not particularly limited in terms of voltage, current density, and the like. Instead, it can be carried out under the conditions normally used as a method for charging and discharging a battery. Further, the method of initiating the chemical reaction and the control of the progress thereof are not particularly limited, and heating or irradiation with energy rays such as ultraviolet rays or electron beams is performed. .

In the present invention, the chemical reaction of the monomer or oligomer can be started at the same time as charging or discharging, or can be started prior to charging or discharging, or after starting charging or discharging. A chemical reaction can also be initiated.

[Current Collector, Separator, etc.] In the method of manufacturing a thin secondary battery according to the embodiment of the present invention, stainless steel, copper,
A current collector (a positive electrode current collector 4, a negative electrode current collector 5) made of a thin film such as nickel or aluminum or a mesh material can also be used. As the separator, a conventionally known porous thermoplastic resin film such as polyethylene or polypropylene is used. Further, for other manufacturing power generation elements such as a method of laminating electrodes, a method of taking out leads, and a method of exteriorizing a power generation element, a conventionally known method for manufacturing a thin secondary battery can be used.

[Thin Secondary Battery] The form of the thin secondary battery manufactured by the method of the embodiment of the present invention is not particularly limited, but it is generally manufactured in a rectangular shape, a coin shape, a sheet shape or the like. . In addition, the method of packaging the power generating element is not particularly limited, and a conventionally known packaging method using a metal case, a resin mold, a laminate film, or the like can be used.

[0042]

Hereinafter, the details of the thin secondary battery of the present invention and the method of manufacturing the same will be specifically described with reference to Examples.
The present invention is not limited to these examples. (Example 1) [Solution containing monomer or oligomer: (a) unsaturated carboxylic acid compound] A glass container (not shown) under a stream of dry nitrogen.
9.85 g of methoxyethyl acrylate and 0.1 of 1,6-hexanediol diacrylate as a crosslinkable monomer.
5 g and a mixed solution comprising 0.1 g of 2,2-azobisdimethylvaleronitrile as a polymerization initiator were injected, and 1
A mixed solution of ethylene carbonate and diethyl carbonate at a mass ratio of 3: 7 in which M LiPF ₆ was dissolved was added, and the whole was uniformly stirred to prepare a solution containing a monomer or oligomer capable of forming a polymer gel.

[Power Generating Element] Next, lithium cobaltate having an average particle size of 5 μm, acetylene black, polyvinylidene fluoride, and N-methyl-2-pyrrolidone were added in an amount of 10: 1: 1: 3.
It was mixed and dispersed at a weight ratio of 0. This was uniformly applied on one side of an aluminum foil by a wire bar method, and vacuum-dried at 100 ° C. for 2 hours to remove the solvent. The obtained thin layer was cut into an appropriate size to prepare a positive electrode layer 2 having a capacity of about 25 mAh. Next, polyvinylidene fluoride and N-methyl-2-
A slurry in which pyrrolidone, petroleum petroleum coke, and acetylene black are mixed at a weight ratio of 1: 30: 20: 1 is cast, uniformly formed by a wire bar method, and then cast.
Vacuum drying was performed at 0 ° C. for 2 hours to produce a negative electrode layer 3. The obtained positive electrode layer 4 and negative electrode layer 4 were made of polyethylene having a thickness of 25.
After laminating and folding a separator film (not shown) having a pore size of 50 μm and a porosity of 50%, extraction electrodes 4 and 5 were attached to the positive electrode and the negative electrode, respectively, to obtain a power generating element.

[Exterior Package] Next, this power generation element was mounted on an aluminum laminate film (not shown) molded according to its shape, and the periphery was heat-sealed except one side. Thereafter, a solution containing a monomer or an oligomer capable of forming the above-mentioned polymer gel was dropped from the unfused side, and the last remaining side was heat-sealed to obtain a thin secondary battery.

[Pressurizing Step, Charging Step] This thin secondary battery is sandwiched between a 5 mm thick stainless steel plate (not shown) having a 2 mm urethane resin layer on the surface, and a pressure of 1 kg / cm ² is applied to the thin secondary battery. Battery (power generation element) added. Raise the temperature of the power generating element (monomer or oligomer) to 80 ° C and simultaneously
Charge the power generating element to 4.3V with a current of A, then 4.
It was kept at a constant voltage of 3 V for 4 hours. After that, when the stainless steel plate was taken out from the thin secondary battery (power generation element), a thin secondary battery that was not easily deformed even by an external force (under atmospheric pressure) was obtained. This is presumably because the monomer or oligomer gelled due to charging.

[Evaluation] A charge / discharge test of the thin secondary battery obtained in this example was performed at room temperature. The charge / discharge efficiency was 99% or more at a discharge rate of 2.5 mA, and the charge / discharge efficiency was 25% at a discharge rate of 25 mA. The discharge efficiency was 95%. A charge / discharge test was performed at -10 ° C.
% Good charge / discharge efficiency was obtained. Further, when the impedance test of the thin secondary battery obtained in this example was performed, the internal impedance of the thin secondary battery determined from the Cole-Cole plot was 100 mΩ. In addition, 5mA
When the charge / discharge test was repeated 100 times at a constant current of 4.2 V and 3.0 V and the capacity of the thin secondary battery hardly changed, good characteristics were observed. In addition, in the thin secondary battery obtained in this example, a phenomenon considered to be caused by a partial short circuit such as incomplete boosting during charging or self-discharge was not observed.

Comparative Example 1 The positive electrode layer, the negative electrode layer
And a separator was used to produce a power generating element in the same manner as in Example 1. The power generating element was mounted on a laminate film cast by the method of Example 1, and a monomer or oligomer capable of forming a polymer gel was added. Sealing was performed by the method 1 to obtain a thin secondary battery.

[No Charging Step] This thin secondary battery was sandwiched between the stainless steel plates of Example 1 (pressurizing step), and the power generating element (monomer or oligomer) was held at 80 ° C. for 8 hours without applying a voltage. As a result, a battery that was not easily deformed by external force was obtained. This is probably because the monomer or oligomer gelled by heating, not by charging. However, when the charge / discharge test of the obtained thin secondary battery was performed at room temperature, the charge / discharge efficiency was 85% at a discharge rate of 2.5 mA, and decreased to 50% at a discharge rate of 25 mA. When a charge / discharge test was performed at −10 ° C., the charge / discharge efficiency was almost 0% at a discharge rate of 2.5 mA. Further, when an impedance test of this thin secondary battery was performed, the internal impedance determined from the Cole-Cole plot was 400 mΩ, which was extremely high. However, when the charge / discharge test was repeated at a constant current of 25 mA and a voltage between 4.2 V and 3.0 V, the capacity of this thin secondary battery was rapidly reduced, and 70% of the initial capacity was obtained in 10 cycles. It became. From the above,
It was found that the thin secondary battery of Comparative Example 1 had inferior battery characteristics as compared with the thin secondary battery of Example 1.

(Comparative Example 2) [Ethylene carbonate / diethyl carbonate mixed solution] A power generating element was prepared in the same manner as in Example 1 using the positive electrode layer, the negative electrode layer, and the separator of Example 1, and Attached to the laminated film molded by the method,
A mixed solution of ethylene carbonate and diethyl carbonate in a mass ratio of 3: 7 in which 1M LiPF ₆ was dissolved was added, and sealing was performed in the same manner as in Example 1 to obtain a thin secondary battery.

This thin secondary battery was sandwiched between the stainless steel plates of Example 1 and charged under the conditions of Example 1 while applying pressure. Thereafter, when the stainless steel plate was taken out, a thin secondary battery which was easily deformed by an external force was obtained. A charge / discharge test of the obtained thin secondary battery was performed at room temperature.
At a discharge rate of 5 mA, the charge / discharge efficiency is 99%,
At a discharge rate of mA, the charge / discharge efficiency was 95%. Further, when an impedance test was performed on this thin secondary battery, the internal impedance determined from the Cole-Cole plot was 70 mΩ. Furthermore, when the charge / discharge test was repeated at a constant current of 25 mA and a voltage between 4.2 V and 3.0 V, the capacity of this thin secondary battery rapidly decreased,
After 10 cycles, the capacity was 80% of the initial capacity. In addition, as the charge / discharge was repeated, the thin secondary battery was bent and deformed significantly. From the above, it was found that the thin secondary battery of Comparative Example 2 had inferior battery characteristics as compared with the thin secondary battery of Example 1.

(Embodiment 2) In this embodiment, only the solution containing the monomer or oligomer, the pressurizing step, the charging step, and the evaluation will be described, and the description (the power generation element and the exterior step) which is the same as that of Embodiment 1 will be omitted. .

[Solution Containing Monomer or Oligomer: (a) Unsaturated Carboxylic Acid Compound] Under a dry nitrogen stream, 20 g of a polymer of 2-hydroxyethyl methacrylate and hexamethylene diisocyanate as a crosslinking component were placed in a glass container (not shown). 1 g of MEK oxime block (manufactured by Sumitomo Bayer Urethane Co., Ltd., trade name: BL3175) was injected, and a mixed solution of ethylene carbonate and diethyl carbonate having a mass ratio of 3: 7 in which 1 M of LiPF ₆ was dissolved was added to make the whole uniform. Stirring was performed to prepare a solution containing a monomer or oligomer capable of forming a polymer gel.

That is, as the monomer or oligomer capable of forming a polymer gel, methoxyethyl acrylate of Example 1, 1,6-hexanediol diacrylate,
Instead of the mixed solution comprising 2-azobisdimethyl valeronitrile, in this embodiment, 2-hydroxyethyl methacrylate polymer and hexamethylene diisocyanate M
A mixed solution comprising the EK oxime block was prepared.

[Pressurizing Step, Charging Step] In the same manner as in Example 1, a thin secondary battery heat-sealed with the mixed solution of the present example was replaced with a 5 mm thick stainless steel having a 2 mm urethane resin layer on the surface. The sheet was sandwiched between plates (not shown), and a pressure of 1 kg / cm ² was applied to a thin secondary battery (power generation element). The temperature of the power generating element (monomer or oligomer) is raised to 60 ° C. instead of 80 ° C., and at the same time, the power generating element is charged to 4.3 V with a current of 0.5 mA, and then maintained at a constant voltage of 4.3 V for 4 hours. did. After that, when the stainless steel plate was taken out from the thin secondary battery (power generation element), a thin secondary battery that was not easily deformed even by an external force (under atmospheric pressure) was obtained. This is presumably because the monomer or oligomer gelled due to charging.

[Evaluation] A charge / discharge test of the thin secondary battery obtained in this example was conducted at room temperature. The charge / discharge efficiency was 99% or more at a discharge rate of 2.5 mA, and the charge / discharge efficiency was 25% at a discharge rate of 25 mA. The discharge efficiency was 90%. In addition, a charge / discharge test was performed at -10 ° C.
% Good charge / discharge efficiency was obtained. Further, when the impedance test of the thin secondary battery obtained in this example was performed, the internal impedance of the thin secondary battery determined from the Cole-Cole plot was 120 mΩ. In addition, 5mA
When the charge / discharge test was repeated 100 times at a constant current of 4.2 V and 3.0 V and the capacity of the thin secondary battery hardly changed, good characteristics were observed. In addition, in the thin secondary battery obtained in this example, a phenomenon considered to be caused by a partial short circuit such as incomplete boosting during charging or self-discharge was not observed.

(Embodiment 3) In this embodiment, only the solution containing the monomer or oligomer, the pressurizing step, the charging step, and the evaluation will be described, and the description (the power generation element and the exterior step) which is the same as that of the first embodiment will be omitted. .

[Solution Containing Monomer or Oligomer: (c) Organosiloxane Compound] Cyclohexene oxide 14.7 was placed in a glass container (not shown) under a stream of dry nitrogen.
g, methyl diethylene glycol glycidyl ether 7
A mixture of 92.9 g and 1.9 g of potassium hydroxide was injected, and a mass ratio of 3: 7 in which 1M LiPF ₆ was dissolved was further added.
Of ethylene carbonate and diethyl carbonate was added and the whole was uniformly stirred to prepare a solution containing a monomer or oligomer capable of forming a polymer gel.

That is, as the monomer or oligomer capable of forming a polymer gel, methoxyethyl acrylate of Example 1, 1,6-hexanediol diacrylate,
In this example, a mixed solution composed of cyclohexene oxide and methyldiethylene glycol glycidyl ether was prepared in place of the mixed solution composed of 2-azobisdimethylvaleronitrile.

In the same manner as in Example 1, a thin secondary battery in which the mixed solution of this example was heat-sealed was sandwiched between a 5 mm-thick stainless steel plate (not shown) having a 2 mm urethane resin layer on the surface. And a pressure of 1 kg / cm ² was applied to a thin secondary battery (power generation element). The temperature of the power generating element (monomer or oligomer) is raised to 60 ° C. instead of 80 ° C., and simultaneously 0.5 mA
The power generation element is charged to 4.3 V with a current of
It was kept at a constant voltage of V for 4 hours. After that, when the stainless steel plate was taken out from the thin secondary battery (power generation element), a thin secondary battery that was not easily deformed even by an external force (under atmospheric pressure) was obtained. This is presumably because the monomer or oligomer gelled due to charging.

[Evaluation] A charge / discharge test of the thin secondary battery obtained in this example was conducted at room temperature. The charge / discharge efficiency was 99% or more at a discharge rate of 2.5 mA, and the charge / discharge efficiency was 25% at a discharge rate of 25 mA. The discharge efficiency was 90%. In addition, a charge / discharge test was performed at -10 ° C.
% Good charge / discharge efficiency was obtained. Further, when the impedance test of the thin secondary battery obtained in this example was performed, the internal impedance of the thin secondary battery determined from the Cole-Cole plot was 150 mΩ. In addition, 5mA
When the charge / discharge test was repeated 100 times at a constant current of 4.2 V and 3.0 V and the capacity of the thin secondary battery hardly changed, good characteristics were observed. In addition, in the thin secondary battery obtained in this example, a phenomenon considered to be caused by a partial short circuit such as incomplete boosting during charging or self-discharge was not observed.

(Embodiment 4) In this embodiment, only the solution containing the monomer or oligomer, the pressurizing step, the charging step, and the evaluation will be described, and the description (the power generation element and the exterior step) which is the same as that of the first embodiment will be omitted. .

[Solution containing monomer or oligomer: (c) organosiloxane compound] 98 g of dimethylvinylsiloxane-terminated polydimethylsiloxane and 0.01 g of hexachloroplatinic acid were placed in a glass container (not shown) under a stream of dry nitrogen.
g, and trimethylsiloxy-terminated polydiorganosiloxane (0.9 g) were added, and the whole was stirred uniformly to prepare a solution containing a monomer or oligomer capable of forming a polymer gel.

That is, as the monomer or oligomer capable of forming a polymer gel, methoxyethyl acrylate of Example 1, 1,6-hexanediol diacrylate,
In this example, a mixed solution composed of dimethylvinylsiloxane-terminated polydimethylsiloxane and trimethylsiloxy-terminated polydiorganosiloxane was prepared in place of the mixed solution composed of 2-azobisdimethylvaleronitrile.

In the same manner as in Example 1, a thin secondary battery in which the mixed solution of this example was heat-sealed was sandwiched between a 5 mm-thick stainless steel plate (not shown) having a 2 mm urethane resin layer on the surface. And a pressure of 1 kg / cm ² was applied to a thin secondary battery (power generation element). The temperature of the power generating element (monomer or oligomer) is raised to 85 ° C. instead of 80 ° C., and simultaneously 0.5 mA
The power generation element is charged to 4.3 V with a current of
It was kept at a constant voltage of V for 4 hours. After that, when the stainless steel plate was taken out from the thin secondary battery (power generation element), a thin secondary battery that was not easily deformed even by an external force (under atmospheric pressure) was obtained. This is presumably because the monomer or oligomer gelled due to charging.

[Evaluation] A charge / discharge test of the thin secondary battery obtained in this example at room temperature showed that the charge / discharge efficiency was 99% or more at a discharge rate of 2.5 mA and a charge / discharge efficiency of 25 mA. The discharge efficiency was 80%. In addition, a charge-discharge test was performed at -10 ° C.
Good charge / discharge efficiency of 5% was obtained. Further, when the impedance test of the thin secondary battery obtained in this example was performed, the internal impedance of the thin secondary battery determined from the Cole-Cole plot was 200 mΩ. In addition, 5m
When the charge / discharge test was repeated 100 times at a constant current of A and between a voltage of 4.2 V and 3.0 V, good characteristics were observed with little change in the capacity of the thin secondary battery. In addition, in the thin secondary battery obtained in this example, a phenomenon considered to be caused by a partial short circuit such as incomplete boosting during charging or self-discharge was not observed.

[0066]

As described above, according to the thin secondary battery and the method of manufacturing the same of the present invention, a power generating element comprising a positive electrode, a negative electrode, and a separator is impregnated with a monomer or an oligomer capable of forming a polymer gel to generate power. In a thin secondary battery having an element and a method for manufacturing the same, a first step of gelling a monomer or oligomer impregnated in the power generation element by a chemical reaction, and charging while applying pressure to the power generation element impregnated with the monomer or oligomer Or a second step of gelling a monomer or oligomer by electric discharge, and a method for manufacturing the same.

[0006] Therefore, since the monomer or oligomer is gelled by charging or discharging, an anisotropy occurs in the ionic conductivity of the gelled gel electrolyte due to the current based on charging or discharging. Thereby, the ionic conductivity of the gel electrolyte in a specific direction, that is, the direction connecting the positive electrode and the negative electrode, is increased. As a result, a gel electrolyte having high ionic conductivity is formed even in minute gaps of the electrode active material,
There is an effect that the output is high and the device can operate stably at a low temperature.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a thin secondary battery according to an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 electrolyte 2 positive electrode active material layer 3 negative electrode active material layer 4 positive electrode current collector 5 negative electrode current collector 6a, 6b encapsulating material

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kentaro Nakahara 5-7-1 Shiba, Minato-ku, Tokyo Within NEC Corporation (56) References JP-A-5-3036 (JP, A) JP-A-11 JP-A-86911 (JP, A) JP-A-11-233147 (JP, A) JP-A-10-321257 (JP, A) JP-A-7-153489 (JP, A) JP-A 2001-35535 (JP, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) H01M 10/40 H01M 6/12 H01M 6/22

Claims (7)

(57) [Claims] In a method for manufacturing a thin secondary battery in which a power generation element comprising a positive electrode, a negative electrode, and a separator is impregnated with a monomer or oligomer capable of forming a polymer gel, and the power generation element is packaged, the power generation element is impregnated. includes a step of gelling by chemical reaction of monomer or oligomer, and a step of gelling the monomer or oligomer by the charging or discharging while applying pressure to the power generating element impregnated with a monomer or oligomer, a monomer addition by the charging or discharging
Before or after the step of gelling the oligomer
The step of gelling the monomer or oligomer by the reaction
A method for producing a thin secondary battery, which is performed . 2. The method according to claim 1, wherein the chemical reaction is started by heating. 3. The method according to claim 2, wherein the monomer or the oligomer is
(a) an unsaturated carboxylic acid compound, (b) a compound comprising at least one of a polyene compound and a polythiol compound, (c) an organosiloxane compound, and (d) a vinyl compound having an amide group. The method for producing a thin secondary battery according to claim 1, wherein the method includes at least one compound from the group. 4. The method of manufacturing a thin secondary battery according to claim 1, wherein the pressure is applied to the power generating element via an elastic body. 5. The thin secondary battery according to claim 1, wherein the positive electrode and the negative electrode are wound flat through the separator. Method. 6. A thin secondary battery comprising a power generating element comprising a positive electrode, a negative electrode and a separator and a polymer gel electrolyte in which a monomer or oligomer is gelled,
The thin secondary battery, wherein the gelation is performed by charging or discharging while applying pressure to a chemical reaction and a power generation element. 7. The method according to claim 7, wherein the monomer or the oligomer is
(a) an unsaturated carboxylic acid compound, (b) a compound comprising at least one of a polyene compound and a polythiol compound, (c) an organosiloxane compound, and (d) a vinyl compound having an amide group. The thin secondary battery according to claim 6, comprising at least one compound from the group.