JP3503293B2 - Thin battery - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a thin battery having a resin film as an exterior material. More specifically, it relates to a thin battery having a liquid crystal polyester resin composition film as an exterior material.

[0002]

2. Description of the Related Art In recent years, electronic devices have become smaller and thinner and lighter. For example, in the field of OA devices, word processors, electronic organizers, electronic still cameras and the like have become thinner and lighter. On the other hand, the batteries used as the power source for such electronic devices are required to be small and thin and have a light weight in the market, and various thin batteries have been developed and improved.

However, in putting these thin batteries into practical use, there are still unsolved problems. For example, although high energy density of an electrode material can be achieved by a lithium secondary battery, development of an appropriate thin battery exterior material is urgently needed in order to reduce weight and thickness.

When a metal such as iron, SUS or aluminum is used as the exterior material, the flexibility of the thin battery is impaired, the weight of the thin battery increases, and there is a risk of short circuit and electric shock. Yes, it is not preferable. In addition, JP-A-61-82
Although Japanese Patent No. 662 describes a thin battery using polyethylene terephthalate (PET) vapor-deposited with silicon oxide as an exterior material, it has insufficient gas barrier properties and bending resistance as the exterior material.

Japanese Patent Laid-Open No. 5-325923 discloses an example in which a film obtained by laminating polyethylene (PE) on PET is used as an exterior material for a thin battery. However, such an exterior material does not have sufficient gas barrier properties and chemical resistance, and in some cases, the electrolytic solution of the battery may leak to the outside, or the electrode or electrolytic solution of the battery may deteriorate.

Japanese Unexamined Patent Publication (Kokai) No. 6-124692 discloses a case in which the exterior material is formed of a plastic protective layer and an inorganic coating layer. However, the exterior material does not have sufficient heat resistance, flexibility and gas barrier properties. There wasn't.

[0007] In addition, as a problem of the conventional thin battery,
Since the adhesive strength between the sealing material of the battery and the exterior material is insufficient, an adhesive layer is required and work efficiency is poor. In addition, there are various problems such as a defect in the sealing portion, deterioration of the exterior material due to the solvent contained in the polymer electrolyte, and liquid leakage.

On the other hand, the liquid crystal polyester is generally called a melt-type liquid crystal (thermotropic liquid crystal) polymer, and is a polyester characterized in that molecules are aligned in a molten state by strong intermolecular interaction. Due to its strong intermolecular interaction and molecular orientation, it is known as a material having high strength, high elastic modulus, high heat resistance, gas barrier property, and chemical resistance.

However, unlike aromatic polyesters such as polyethylene terephthalate and polybutylene terephthalate, liquid crystal polyesters do not entangle even in a melted state because the molecules are rigid, and the molecular chains are remarkably oriented in the flow direction. It also exhibits a behavior in which the melt viscosity sharply decreases due to shearing, and a behavior in which the melt viscosity sharply decreases due to temperature rise and the melt tension during melting is extremely low. Therefore, it is very difficult to maintain the shape in the molten state, and further, since the molecules are oriented, it is difficult to balance the performance in the vertical and horizontal directions, and in an extreme case, the film is torn in the molecular orientation direction.
There is a problem that it is difficult to perform blow molding. for that reason,
A film made of liquid crystal polyester, which takes advantage of the function of liquid crystal polyester, has not been put to practical use sufficiently.

[0010]

In view of the above situation, the object of the present invention, that is, the object of the present invention, is to provide excellent gas barrier properties, chemical resistance, heat resistance, adhesiveness, etc. and good film forming processability. Another object of the present invention is to provide a thin battery having a flexible resin film as an exterior material.

[0011]

[Means for Solving the Problems] The inventors of the present invention have made extensive studies in order to solve such problems, and arrived at the present invention. That is, the present invention relates to (A) liquid crystal polyesters 56 to 9
A liquid crystal polyester resin composition film comprising a liquid crystal polyester resin composition containing 9% by weight and (B) 44 to 1% by weight of an epoxy group-containing ethylene copolymer consisting of the following (a) to (c) as an exterior material. The present invention relates to a thin battery. (A) 50 to 99.9% by weight of ethylene units (b) 0.1 to 30% by weight of unsaturated carboxylic acid glycidyl ester units or unsaturated glycidyl ether units (c) 0 to ethylenically unsaturated ester compound units Four
9.9% by weight

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in detail.
The liquid crystal polyester of the component (A) of the liquid crystal polyester resin composition forming the exterior material of the thin battery in the present invention is
It is a polyester called thermotropic liquid crystal polymer. Specifically, (1) a combination of an aromatic dicarboxylic acid, an aromatic diol and an aromatic hydroxycarboxylic acid, (2) a combination of different aromatic hydroxycarboxylic acids, (3) an aromatic Examples include a combination of a dicarboxylic acid and a nuclear-substituted aromatic diol, (4) a polyester obtained by reacting a polyester such as polyethylene terephthalate with an aromatic hydroxycarboxylic acid, and the like. Anisotropy at a temperature of 400 ° C. or lower. It forms a melt. Incidentally, instead of these aromatic dicarboxylic acids, aromatic diols and aromatic hydroxycarboxylic acids, ester-forming derivatives thereof may be used. Examples of the repeating structural unit of the liquid crystal polyester include the following, but are not limited thereto. Repeating structural unit derived from aromatic dicarboxylic acid:

[Chemical 5]

[0013]

[Chemical 6] Repeating structural units derived from aromatic diols:

[0014]

[Chemical 7]

[0015]

[Chemical 8] Repeating structural unit derived from aromatic hydroxycarboxylic acid:

[0016]

[Chemical 9]

From the viewpoint of the balance of heat resistance, mechanical properties and processability, a particularly preferred liquid crystal polyester is

[Chemical 10] The following combinations (I) to (V) of the repeating structural units are specifically included.

[0018]

[Chemical 11]

[0019]

[Chemical 12]

[0020]

[Chemical 13]

[0021]

[Chemical 14]

[0022]

[Chemical 15]

Regarding the production method of the liquid crystal polyesters (I) to (V), for example, Japanese Patent Publication No. 47-47870,
JP-B-63-3888, JP-B-63-3891, JP-B-56-18016, JP-A-2-51
No. 523, etc. Among these, the combination of (I), (II) and (IV) is preferable, and the combination of (I) and (II) is more preferable.

When high heat resistance is required in the liquid crystal polyester resin composition of the present invention, the liquid crystal polyester of the component (A) contains 30 to 80 mol% of the following repeating units (a ') and repeating units ( A liquid crystal polyester in which b ') is 0 to 10 mol%, the repeating unit (c') is 10 to 25 mol%, and the repeating unit (d ') is 10 to 35 mol% is preferably used.

[0025]

[Chemical 16] (In the formula, Ar is a divalent aromatic group.)

The epoxy group-containing ethylene copolymer which is the component (B) of the liquid crystal polyester resin composition in the present invention means (a) an ethylene unit of 50 to 99.9% by weight,
(B) 0.1 to 30% by weight of unsaturated carboxylic acid glycidyl ester units or unsaturated glycidyl ether units,
The epoxy group-containing ethylene copolymer is preferably 0.5 to 20% by weight and (c) the ethylenically unsaturated ester compound unit is 0 to 49.9% by weight, preferably 0.5 to 40% by weight.

The compounds that give the unsaturated carboxylic acid glycidyl ester unit and unsaturated glycidyl ether unit (b) in the epoxy group-containing ethylene copolymer (B) are represented by the following general formulas 17 and 18, respectively.

[Chemical 17] (R is a C2-C13 hydrocarbon group having an ethylenically unsaturated bond.)

[Chemical 18] (R is a hydrocarbon group having 2 to 18 carbon atoms which has an ethylenically unsaturated bond, X is -CH ₂ -O- or

[Chemical 19] Is. )

Specific examples include glycidyl acrylate, glycidyl methacrylate, itaconic acid glycidyl ester, allyl glycidyl ether, 2-methylallyl glycidyl ether, and styrene-p-glycidyl ether.

Further, the epoxy group-containing ethylene copolymer in the present invention includes a terpolymer or more terpolymer of unsaturated carboxylic acid glycidyl ester or unsaturated glycidyl ether and ethylene and (c) ethylenic unsaturated ester compound. Can also be used.

Examples of the ethylenically unsaturated ester compound (c) include carboxylic acids such as vinyl acetate, vinyl propionate, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate and butyl methacrylate. Vinyl ester, α, β-
Unsaturated carboxylic acid alkyl ester etc. are mentioned. Particularly, vinyl acetate, methyl acrylate, and ethyl acrylate are preferable.

Specific examples of the epoxy group-containing ethylene copolymer (B) used in the present invention include, for example, a copolymer comprising ethylene units and glycidyl methacrylate units,
Copolymers consisting of ethylene units and glycidyl methacrylate units and methyl acrylate units, copolymers consisting of ethylene units and glycidyl methacrylate units and ethyl acrylate units, copolymers consisting of ethylene units and glycidyl methacrylate units and vinyl acetate units, and the like. To be

The melt index (hereinafter sometimes referred to as MFR; JIS K6760, 190 ° C., 2.16 kg load) of the epoxy group-containing ethylene copolymer is preferably 0.5 to 100 g / 10 minutes, and further, It is preferably 2 to 50 g / 10 minutes. The melt index may be out of this range, but if the melt index exceeds 100 g / 10 min, it is not preferable in terms of mechanical properties when the composition is formed, and if it is less than 0.5 g / 10 min, the component (A) is Is inferior in compatibility with the liquid crystal polyester and is not preferable.

Epoxy group-containing ethylene used in the present invention
The copolymer (B) has a flexural rigidity of 10 to 1300 kg /
cm²The range is preferably 20 to 1100 kg /
cm ²Are more preferable. Bending rigidity is in this range
If the composition is outside, the moldability and mechanical properties of the composition are insufficient.
May occur, which is not preferable.

The epoxy group-containing ethylene copolymer is usually an unsaturated epoxy compound and ethylene in the presence of a radical generator at 500 to 4000 at 100 to 300 ° C. in the presence or absence of a suitable solvent or chain transfer agent. It is produced by a method of copolymerizing below. It can also be produced by a method of mixing an unsaturated epoxy compound and a radical generator with polyethylene and performing melt graft copolymerization in an extruder.

The ratio of the component (A) to the component (B) in the liquid crystal polyester resin composition used in the present invention is such that the component (A) is 56 to 99% by weight, preferably 70 to 98% by weight, and the component (B). Is 44 to 1% by weight, preferably 30 to 2
% By weight. When the amount of the component (A) is less than 56% by weight, the heat resistance of the composition is lowered, which is not preferable. On the other hand, if the content of the component (A) exceeds 99% by weight, the effect of improving the anisotropy of the composition may not be sufficient, which is also unfavorable in terms of cost.

The method for producing the liquid crystal polyester resin composition in the present invention is not particularly limited, and known methods can be used. For example, a method of mixing each component in a solution state and evaporating the solvent or precipitating in the solvent can be mentioned. From an industrial point of view, a method of kneading each component in a molten state is preferable. For melt kneading, generally used kneading devices such as a single-screw or twin-screw extruder and various kneaders can be used. A biaxial high kneader is particularly preferable. In the melt-kneading, the cylinder temperature of the kneading device is preferably in the range of 200 to 360 ° C, more preferably 230 to 340 ° C. It is also possible to directly obtain the composition film by mixing and melting and kneading the respective components in the process of forming the liquid crystal polyester resin composition film without going through the kneading process beforehand.

Upon kneading, the respective components may be mixed in advance by a device such as a tumbler or a Henschel mixer, or if necessary, the mixing may be omitted and the respective amounts may be separately supplied to the kneading device. Methods can also be used.

In the liquid crystal polyester resin composition used in the present invention, an inorganic filler is optionally used.
Such inorganic fillers include calcium carbonate, talc, clay, silica, magnesium carbonate, barium sulfate, titanium oxide, alumina, gypsum, glass flakes, glass fibers, carbon fibers, alumina fibers, silica-alumina fibers, aluminum borate. Examples thereof include whiskers and potassium titanate fibers.

The liquid crystal polyester resin composition used in the present invention may further contain an organic filler, an antioxidant, a heat stabilizer, a light stabilizer, a flame retardant, a lubricant, an antistatic agent, if necessary.
Various additives such as inorganic or organic colorants, rust preventives, cross-linking agents, foaming agents, fluorescent agents, surface smoothing agents, surface gloss improvers, release improvers such as fluororesins, etc. may be added during or after the manufacturing process. It can be added in the processing step.

The thin battery of the present invention is characterized by using a film made of the above liquid crystal polyester resin composition as an exterior material. It is also possible to use a laminated material of the film and a layer made of another material.

A film made of such a liquid crystal polyester resin composition is not particularly limited in film forming method, but the liquid crystal polyester resin composition obtained by the above method is melt-kneaded by an extruder and extruded through a T-die. A uniaxially oriented film or a biaxially oriented film obtained by winding the molten resin while stretching in the winding machine direction (longitudinal direction) is preferably used.

The setting conditions of the extruder at the time of forming the uniaxially oriented film can be appropriately set according to the composition of the composition.
The cylinder set temperature is preferably 200 to 360 ° C, more preferably 230 to 340 ° C. If it is out of this range, thermal decomposition of the composition may occur or film formation may become difficult, which is not preferable.

The slit spacing of the T-die is generally 0.
It is 2 to 0.8 mm, and the draft ratio of the uniaxially oriented film is preferably in the range of 1.1 to 40.0.
The draft ratio here means a value obtained by dividing the cross-sectional area of the T-die slit by the cross-sectional area of the film in the longitudinal direction. If the draft ratio is less than 1.1, the film strength is insufficient,
If the draft ratio exceeds 40.0, the surface smoothness of the film may become insufficient, which is not preferable. The draft ratio can be set by controlling the setting conditions of the extruder, the winding speed, and the like.

The biaxially stretched film has the same extruder setting conditions as those for forming the uniaxially oriented film, that is, the cylinder set temperature is preferably 200 to 360 ° C., more preferably 230 to 340 ° C., and T-die. The composition is melt-extruded with the slit spacing of preferably in the range of 0.2 to 0.8, and the melt sheet extruded from the T-die is simultaneously stretched in the longitudinal direction and in the direction perpendicular to the longitudinal direction (transverse direction). Or a sequential drawing method in which the melt sheet extruded from the T-die is first stretched in the longitudinal direction, and then this stretched sheet is stretched in the transverse direction by a tenter in the same process at a high temperature of 100 to 300 ° C. To be

An inflation film, which can be said to be a kind of biaxially stretched film obtained by forming a melt sheet extruded from a cylindrical die by an inflation method, is also preferably used as a film made of the liquid crystal polyester resin composition of the present invention. To be

When obtaining a biaxially oriented film, the stretching ratio is preferably 1.1 to 20 times in the longitudinal direction and 1.1 to 20 times in the transverse direction. If the stretching ratio is out of the above range, the strength of the composition film may be insufficient, or it may be difficult to obtain a film having a uniform thickness, which is not preferable.

The film made of the liquid crystal polyester resin composition of the present invention and the thin battery sealing material have good adhesiveness, and usually an adhesive is not necessary and they are bonded by pressure bonding. Preferably, they are bonded by thermocompression.

The thickness of the liquid crystal polyester resin composition film as the exterior material in the present invention is not particularly limited and can be selected from the film to the sheet according to the purpose, but the thickness of 1 to 1000 μm is preferable. Used.

The thin batteries in the present invention typically include non-aqueous lithium primary batteries and secondary batteries.
It is composed of members such as a negative electrode and an electrolyte. Hereinafter, a lithium secondary battery will be described in more detail as an example, but these are merely examples and do not limit the application of the present material in any way.

The negative electrode in a thin battery uses a material capable of being doped or dedoped with lithium metal or lithium ions as an active material, and if necessary, a suitable binder such as polyethylene, polypropylene or fluororesin, and further necessary. In that case, a material having a constitution in which it is mixed with a conductive material and molded by a method such as compression and closely adhered to a current collector can be mentioned.

Materials which can be used for the negative electrode of such a thin battery and which can be doped with lithium ions and dedoped are as follows:
Other than the lithium aluminum alloy, natural graphite, artificial graphite, coke, carbon black, pyrolytic carbon, carbon fiber, and a carbon material obtained by firing a polymer compound can be exemplified. Moreover, the composite material which has these carbon materials as a main component can be illustrated.

The positive electrode in a thin battery is a mixture of a conductive material and a suitable binder such as polyethylene, polypropylene, or fluororesin, which is made of a material capable of doping or dedoping lithium ions as an active material, and compressed. Examples of the structure that are formed by the method described above and are in close contact with the current collector.

As the active material capable of being doped with lithium ions and used for the positive electrode of such a thin battery, a layered lithium composite oxide having a so-called α-NaFeO ₂ type structure as a base, and a spinel type structure as a base Examples thereof include transition metal oxides, lithium composite oxides, and transition metal chalcogenides.

Further, as the positive electrode active material, a layered lithium composite oxide of a transition metal such as vanadium, manganese, iron, cobalt or nickel, or lithium cobalt.
Examples are layered lithium composite oxides mainly composed of nickel composite oxides.

As the lithium salt, any of the conventionally known ones can be used. LiClO ₄ , LiPF ₆ , LiA
sF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF
₃ SO ₂ ) _{2 and the} like can be exemplified. Among them, LiPF ₆ , LiBF _{4 and the} like, which have high electric conductivity and low toxicity, are preferable.

In a thin battery, the electrolytic solution contains at least one of the above lithium salts, and the lithium salt is used in an amount of 0.
It is dissolved in a concentration range of 1M (mol / liter) to 2M. Above all, a concentration range of 0.5M to 1.5M is preferable. As the electrolytic solution, a suitable one can be selected from known solid electrolytes or organic electrolytic solutions, and propylene carbonate-based or ethylene carbonate-based ones are preferably used.

As the sealing material for the thin type battery, polymer materials such as polyolefin and engineering plastics can be used.

A separator can be used in a thin battery. Examples of the separator include a porous film of an olefin resin such as a fluororesin or polyethylene or polypropylene, an olefin resin such as a fluororesin, polyethylene or polypropylene, or a nonwoven fabric such as nylon.

[0059]

Surprisingly, the film of the liquid crystal polyester resin composition according to the present invention has a gas barrier property and a chemical resistance which are different from those of the liquid crystal polyester, although the film contains the epoxy group-containing ethylene copolymer as a constituent component. It is not inferior in comparison. By using the film as an exterior material for a thin battery, it has an effect of preventing water vapor, oxygen, etc. from entering the inside of the thin battery, and also has a function of preventing leakage of the electrolytic solution inside the thin battery. Further, since the thin battery exterior material in the present invention is such a resin film, the battery is lightweight, there is no danger of short circuit or electric shock, and the liquid crystal polyester resin composition film in the present invention can be heat-sealed. Therefore, it can be easily heat-sealed with the frame-shaped seal sealing material in a thin battery as an exterior material without an adhesive.

Further, since the liquid crystal polyester resin composition film of the present invention can be thinned and is highly flexible, a thin battery of any shape can be manufactured.

[0061]

EXAMPLES The present invention will be described below with reference to examples, but these are merely examples and the present invention is not limited to these. (1) Component (A) in liquid crystal polyester resin composition
Liquid crystalline polyester (i) p-acetoxybenzoic acid 10.8 kg (60 mol), terephthalic acid 2.49 kg (15 mol), isophthalic acid 0.83 kg (5 mol) and 4,4′-diacetoxydiphenyl 5.45 kg. (20.2 mol) was charged into a polymerization tank having a comb-shaped stirring blade, and the temperature was raised with stirring under a nitrogen gas atmosphere to carry out polymerization at 330 ° C. for 1 hour. During this period, acetic acid gas produced as a by-product was liquefied by a cooling tube, collected and removed, and polymerization was performed under strong stirring. Then, the system was gradually cooled, and the polymer obtained at 200 ° C. was taken out of the system.
The obtained polymer was pulverized with a hammer mill manufactured by Hosokawa Micron Co., Ltd. to obtain particles of 2.5 mm or less. This is further heated in a rotary kiln under a nitrogen gas atmosphere at 280 ° C.
Was treated for 3 hours to obtain a particulate wholly aromatic polyester having a repeating temperature of 324 ° C. and comprising the following repeating structural unit. Here, the flow temperature means a resin heated at a temperature rising rate of 4 ° C./min using a high-performance flow tester CFT-500 manufactured by Shimadzu Corporation under a load of 100 kgf / c.
The temperature at which the melt viscosity is 48,000 poise when extruded from a nozzle having an inner diameter of 1 mm and a length of 10 mm under m ² . Hereinafter, the liquid crystal polyester is abbreviated as A-1. This polymer exhibited optical anisotropy at 340 ° C. or higher under pressure. The repeating structural unit of the liquid crystal polyester A-1 is as follows.

[0062]

[Chemical 20]

(Ii) p-hydroxybenzoic acid 16.6k
g (12.1 mol), 6-hydroxy-2-naphthoic acid 8.4 kg (4.5 mol) and acetic anhydride 18.6 kg
(18.2 mol) was charged into a polymerization tank with a comb-shaped stirring blade,
The temperature is raised with stirring under a nitrogen gas atmosphere, and the temperature is set to 1 at 320 ° C.
320 ° C. under reduced pressure of 2.0 torr
It was polymerized for 1 hour. During this period, acetic acid produced as a by-product was continuously distilled out of the system. Then, the system was gradually cooled, and the polymer obtained at 180 ° C. was taken out of the system. The obtained polymer was pulverized in the same manner as in the above (i), and then treated in a rotary kiln under a nitrogen gas atmosphere at 240 ° C. for 5 hours to obtain the following repeating units in the form of particles having a flow temperature of 270 ° C. A wholly aromatic polyester was obtained. Hereinafter, the liquid crystal polyester is abbreviated as A-2. This polymer exhibited optical anisotropy at 280 ° C. or higher under pressure. The ratio of the repeating structural units of the liquid crystal polyester A-2 is as follows.

[0064]

[Chemical 21]

(2) Component (B) Epoxy Group-Containing Ethylene Copolymer Component Abbreviation of the epoxy group-containing ethylene copolymer obtained by the high pressure radical polymerization method, copolymer composition (weight ratio), melt flow index ( MFR) and flexural rigidity are as follows. Here, MFR is based on JIS K6760 1
Value at 90 ° C and 2.16 kg load (unit: g / 10
min), and the flexural rigidity is a value based on ASTM D747.

Abbreviation: bb-1 (Sumitomo Chemical Co., Ltd., trade name Bond First 7M) Weight ratio: E / GMA / MA = 64/6/30 MFR = 9, Bending rigidity = 40 kg / cm ² Abbreviation: bb-2: (Sumitomo Chemical Co., Ltd. trade name: Bondfast 20B) Weight ratio: E / GMA / VA = 83/12/5 MFR = 20, flexural rigidity = 130 kg / cm ² (where E is (Ethylene, GMA are glycidyl acrylate, MA is methyl acrylate, and VA is vinyl acetate.)

(3) Method for measuring gas barrier property Regarding the obtained liquid crystal polyester resin composition film,
The gas barrier property was measured in the following manner. Oxygen gas permeability: JIS K7126 A method (differential pressure method)
According to the above, measurement was performed using oxygen gas at a temperature of 20 ° C. The unit is cc / m ² · 24 hr · 1 atm. Water vapor transmission rate: Measured according to JIS Z0208 (cup method) under the conditions of a temperature of 40 ° C. and a relative humidity of 90%. The unit is g / m ² · 24 hr · 1 atm.

Reference Example Each component having the composition shown in Table 1 was mixed with a stabilizer in a Henschel mixer, and melt-kneaded at a cylinder set temperature of 297 to 342 ° C. using a TEX-30 twin-screw extruder manufactured by Nippon Steel Co., Ltd. Performed to obtain a composition. The pellets of this composition were melt-kneaded at a cylinder setting temperature of 290 to 342 ° C. and a rotation speed of 40 rpm using a 30 mmφ single-screw extruder equipped with a cylindrical die to obtain a diameter of 100 mm, a lip interval of 1.5 mm, and a die setting temperature of 280 to 280. Molten resin is extruded upward from a cylindrical die at 340 ° C., dry air is pressed into the hollow portion of the tubular film to expand the tubular film, and then the tubular film is cooled and passed through a nip roll to take up speed of 10 to 20 m / I took it in min. Table 1 shows the physical property values of the obtained liquid crystal polyester resin film.

[0069]

[Table 1]

Example 1 The positive electrode of the thin lithium battery used in the test was obtained by the method described below. To 87% by weight of lithium cobalt oxide powder, 1% by weight of acetylene black (product name: Denka Black 50% pressed product manufactured by Denki Kagaku Kogyo Co., Ltd.) having a number average primary particle size of 40 nm, and a weight average particle size of 7.2 μm Scale-shaped artificial graphite (Lonza Co., Ltd., trade name: KS15) 9% by weight
3% by weight of polyvinylidene fluoride with N-methylpyrrolidone as a solvent was added as a binder to the mixture of the above and sufficiently kneaded to obtain a paste. The paste was dried, compression-molded, adhered to an expanded metal made of aluminum as a current collector, and then cut into a square having a thickness of 300 μm and a side of 3.2 cm × 3.2 cm to obtain a positive electrode. As a separator, a polypropylene porous film (manufactured by Daicel Chemical Industries, Ltd., trade name: Celguard # 2)
400) was used. The thickness is 25 μm.

The negative electrode carbon powder was obtained by the method described below. Three
Heat treated at 000 ° C, the specific surface area by nitrogen adsorption method is 9
95 parts by weight of natural graphite powder having a m ² / g, a number average particle size of 10 μm and a true specific gravity of 2.26, the specific surface area by the nitrogen adsorption method graphitized at 2800 ° C. is 30, and the true specific gravity is 2. A silane coupling agent (manufactured by Nippon Unicar Co., Ltd., using a mixed carbon material with 5% by weight of 04 pseudo-graphitic carbon black powder (manufactured by Tokai Carbon Co., Ltd., trade name: TB3800)
1 part by weight of a product in which the product name: A186) was purely dispersed was added, thoroughly mixed and vacuum dried at 150 ° C. to obtain a carbon powder treated with a silane coupling agent.

To 90% by weight of the silane coupling agent-treated material, 10% by weight of polyvinylidene fluoride using N-methylpyrrolidone as a solvent as a binder was added and sufficiently kneaded to obtain a paste. The paste was dried, compression-molded, and brought into close contact with a copper expanded metal which was a current collector, and had a thickness of 300 μm and a side of 3.2 cm × 3.
It was cut into a 2 cm square to obtain a negative electrode.

As a non-aqueous electrolyte solvent, a mixture of dimethyl carbonate, ethyl methyl carbonate and ethylene carbonate in a volume ratio of 35:35:30 was used, and LiPF ₆ was used as an electrolyte in the solvent so that LiPF ₆ was 1 mol / liter. A non-aqueous electrolyte solution dissolved in was used. All the members of the positive electrode, the negative electrode, the separator, and the battery were dried under reduced pressure at 50 ° C. for 24 hours or more except for the electrolytic solution. Then, the positive electrode and the negative electrode were laminated with a separator impregnated with an electrolytic solution sandwiched therebetween, and thermocompression-bonded to a polyethylene terephthalate sealing material using the liquid crystal polyester resin composition film G-1 for exterior packaging. A cross-sectional view of the thin battery thus manufactured is shown in FIG. The lithium secondary battery, which is this thin battery, has an initial capacity of 22.5 mA.
After charging at h, a deterioration test was carried out by leaving it for 20 days at a temperature of 25 ° C. and a humidity of 90%, and the discharge capacity of the battery was measured at room temperature. The capacity retention rate was 99.8%.

Example 2 G as a liquid crystal polyester resin composition film for the exterior material
A thin battery was prepared in the same manner as in Example 1 except that No. -4 was used, charged under the same conditions as in Example 1, and subjected to a deterioration test. As a result, the capacity retention was 98.9%.

Comparative Example 1 A thin battery was prepared in the same manner as in Example 1 except that a polyethylene terephthalate film having a thickness of 70 μm was used as the exterior material, charged under the same conditions as in Example 1, and subjected to a deterioration test. As a result, the capacity retention rate was 39.7%.

[0076]

EFFECT OF THE INVENTION The thin battery outer packaging material comprising the liquid crystal polyester resin composition film of the present invention is excellent in gas barrier property, chemical resistance and heat resistance, and has good adhesiveness with a sealing material. It is possible to obtain a thin battery that has a long life and is inexpensive. The thin battery of the present invention is, for example, a calculator, a personal computer, a pager, a mobile phone, a radio,
It can be used as a power source for communication devices, toys, etc.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a thin battery manufactured in an example which is an example of an embodiment of the present invention.

[Explanation of symbols]

1 ... Exterior material 2 ... Positive electrode current collector 3 ... Positive electrode active material 4 ... Electrolyte / separator 5: Negative electrode active material 6 ... Negative electrode current collector 7 ... Sealing material

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-1-193351 (JP, A) JP-A-1-121357 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08L 67/00-67/04 H01M 2/02

Claims (7)

(57) [Claims] 1. A liquid crystal polyester resin composition containing (A) 56 to 99% by weight of a liquid crystal polyester, and (B) 44 to 1% by weight of an epoxy group-containing ethylene copolymer consisting of the following (a) to (c). A thin battery, comprising a liquid crystal polyester resin composition film of (A) 50 to 99.9% by weight of ethylene units (b) 0.1 to 30% by weight of unsaturated carboxylic acid glycidyl ester units or unsaturated glycidyl ether units (c) 0 to ethylenically unsaturated ester compound units Four
9.9% by weight 2. The thin battery according to claim 1, wherein the liquid crystal polyester (A) is obtained by reacting an aromatic dicarboxylic acid, an aromatic diol and an aromatic hydroxycarboxylic acid. 3. The thin battery according to claim 1, wherein the liquid crystal polyester (A) is obtained by reacting a combination of different aromatic hydroxycarboxylic acids. 4. The thin battery according to claim 1, wherein the liquid crystal polyester (A) contains the following repeating unit. [Chemical 1] 5. The thin battery according to claim 1, wherein the liquid crystal polyester (A) is composed of the following repeating units. [Chemical 2] 6. The thin battery according to claim 1, wherein the liquid crystal polyester (A) is composed of the following repeating units. [Chemical 3] 7. The thin battery according to claim 1, wherein the liquid crystal polyester (A) is composed of the following repeating units. [Chemical 4]