JPS63244552A - Thin type battery - Google Patents

Abstract

PURPOSE:To improve long-term preservation stability by using an adhesive polyolefine composition, which is an admixture of specified ingredients in a specified ratio, as a sealing material. CONSTITUTION:As a sealing material an adhesive polyolefine composition is used, in which at least three kinds of ingredients out of (a)-(e) shall be included and their blending percentages are as follows: (a): 10 to 95 weight %, (b): 0 to 85 weight %, (c): 5 to 60 weight % of a polymer weight, and a total of (a)-(c): 50 to 90 weight %, (d): 5 to 50 weight %, (e): 0 to 45 weight %, a total of (d) and (e): 10 to 50 weight % of the total of the composition. In above expressions, (a) is denatured polyolefine which is obtained from a compound of polyolefine and organic silane of unsaturated bond with ethylene or from an unsaturated compound of a polar group, (b) is undenatured polyolefine, (c) is a polymer whose tensile elastic modulus is lower than that of a polyolefine polymer, (d) is powdered calcium carbonate, and (e) is an inorganic substance excluding calcium carbonate.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention seals the peripheral edge of an exterior plate that also serves as a current collector for both positive and negative electrodes with a sealing material that has excellent adhesive properties, bending properties, and heat shock resistance. The present invention relates to a thin battery with excellent long-term storage stability.

[Technical background of the invention and its problems] Recently, as electronic devices have become smaller and thinner,
There is also a strong demand for smaller size and S film in the batteries used as power sources for these devices. In particular, so-called sheet batteries and paper batteries, which are suitable for card-type electronic devices such as memory cards and IC cards, have been put into practical use. In order to make these batteries thinner, the method of sealing the batteries has become a major technical issue.

For these thin batteries, a structure has been proposed in which the periphery of a flat exterior plate with both positive and negative electrodes, which also serves as a current collector, is sealed with a thermoadhesive resin.

This thermoadhesive resin is required to have the following properties. In other words, as the thickness of the positive and negative electrodes becomes smaller,
There is a need for a sealing material that maintains sufficient insulation between the two electrodes, has good adhesion, does not leak electrolyte, and has excellent long-term storage stability. Furthermore, from the viewpoint of high energy density, lithium was used as the negative electrode active material, and a non-aqueous electrolyte in which an inorganic salt was dissolved in an organic solvent was used as the electrolyte. 2. Description of the Related Art Thin film batteries based on so-called non-aqueous electrolyte lithium batteries are being actively developed. In this case, the sealing material must also have characteristics such that it is difficult to absorb moisture that easily reacts with lithium from the outside, is chemically stable to organic electrolytes, and does not cause 11 moisture.

Various polyolefin resins, fluorine resins, and modified products thereof have been proposed as heat-adhesive resins that satisfy these characteristics.
No. 232, No. 60-14753, No. 60-14805
No. 0, No. 6゜-160559, No. 60-185359
No. 60-185360, No. 80-220553.

No. 61-68860, No. 61-185867.

No. 61-74256, No. 61-176054.

No. 61-185867 and the like are disclosed.

These methods utilize the fact that polyolefin resin is nonpolar and therefore has excellent chemical and electrical properties. However, polyolefin resins have poor adhesive properties, and therefore, the above-mentioned conventional technology proposes the use of modified products such as copolymers of ethylene and vinyl acetate, ionomer resins, or polyolefin resins grafted with unsaturated carboxylic acids. are doing.

However, these modified products do not necessarily have sufficient adhesion to satisfy the above-mentioned required properties as a sealing material, and batteries using these as a sealing material have problems with long-term reliability. There is a need for a sealing material that has even better adhesion, bending properties, and heat shock resistance.

Therefore, various improvement methods have been proposed in order to impart adhesive properties to polyolefin resins. As one of them,
The polyolefin resin is γ-methacryloyloxypropyltrimethoxysilane.

A method has been proposed for improving the adhesive properties of polyolefin resins by modifying them with a type of modifier selected from glycidyl methacrylate and an organic peroxide. However, the improvement in adhesion of modified polyolefins obtained by this method is still not satisfactory.

In addition, thin batteries require good bending properties, and the sealing material must maintain adhesion to the exterior plate after a bending test and must not cause cracks or the like.

Modified polyolefins obtained by the conventional methods described above are insufficient in these properties.

Therefore, the object of the present invention is to improve the shortcomings of conventional thin film batteries. Adhesion and bending properties.

The object of the present invention is to provide a thin film battery with excellent long-term stability using a sealing material with excellent heat shock resistance.

[Means for solving the problem] The present invention includes a separator containing an electrolyte or a solid electrolyte diaphragm between a positive electrode and a negative electrode inside an exterior plate consisting of a pair of opposing thin metal plates that also serves as a current collector. A thin battery in which the periphery of the exterior plate is sealed with a sealing material, and the sealing material contains at least three of the following components (a) to (e). The blending ratio is 10 to 95% by weight of (a) and 0 to 85% by weight of (b) in the weight of the polymer.
, (c) is 5 to 60% by weight, and (a
), (b) and (c) in a total of 50 to 90% by weight, (d
) is 5 to 50% by weight, (e) is 0 to 45% by weight, (d)
A thin battery characterized by using an adhesive polyolefin composition in which the sum of (e) and (e) is 10 to 50% by weight.

(a) A modified polyolefin obtained by grafting a polyolefin with an organosilane compound having an ethylenically unsaturated bond or an unsaturated compound having a polar group (b) An unmodified polyolefin (c) An elastomer (d) Calcium carbonate ( e) The above objective is achieved by providing an inorganic substance other than calcium carbonate.

Each component of the encapsulant composition used in the thin battery of the present invention will be explained in detail.

The modified polyolefin (a) used in the present invention is obtained by grafting a polyolefin with an organic silane compound having an ethylenically unsaturated bond or an unsaturated compound having a polar group, preferably in the presence of an organic peroxide. .

The polyolefins mentioned above include crystalline homopolymers of propylene, propylene and other α-olefins (e.g. yc-
ti, ethylene, butene, pentene.

hexene, heptene, etc.), propylene polymers such as two or more block or random copolymers with diene, ethylene homopolymers, ethylene and α-olefins (propylene, butene, pentene, hexene, heptene, etc.) , ethylene polymers such as two or more block or random copolymers with dienes.

The organic silane compound having an ethylenically unsaturated bond is vinyltriethoxysilane.

Methacryloyloxytrimethoxysilane.

Examples include γ-methacryloyloxypropyltrimethoxysilane, methacryloyloxycyclohexyltrimethoxysilane, γ-methacryloyloxypropyltriacetyloxysilane, methacryloyloxytriethoxysilane, γ-methacryloyloxypropyltriethoxysilane, and the like.

Moreover, as an unsaturated compound which has a polar group, allyl glycidyl ether, 2-methyl-allyl glycidyl ether, and sodium acrylate.

Sodium methacrylate, calcium acrylate, calcium methacrylate, magnesium acrylate, magnesium methacrylate, zinc acrylate, zinc methacrylate, aluminum acrylate, aluminum methacrylate, iron acrylate (■), methacrylate Metal salt compounds of (meth)acrylic acid such as iron(III) acid,
triallyl cyanurate, tri(2-methylallyl)cyanurate), 1,3.5-)lyacryloylhexahydro-5-triazine, 1,3.5-)remethacryloylhexahydro-S-)lyazine, 4- Acryloyloxyphenol, 4-(acryloyloxymethyl)phenol, 4-acryloyloxybenzyl alcohol, 4-methacryloyloxyphenol, 4
-methacryloyloxybenzyl alcohol, 4-(
Examples include methacryloyloxymethyl)benzyl alcohol.

Among these, organic silane compounds are preferable, and the aforementioned modifiers (organosilane compounds or unsaturated compounds having a polar group) may be used alone or in combination of two or more. .

Furthermore, the organic peroxide mentioned above is preferably one having a half-life temperature of about 160 to 260"0, such as nate, di-tert-butyl ciba-oxyphthalate, tert-butyl peroxyacetate, 2
．． 5-dimethyl-2,5-di(tert-butylperoxy)
Hexane.

2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3, tert-butyl peroxylaurate, tert-butyl peroxymaleic acid, tert-butyl peroxybenzoate, methyl ethyl ketone peroxy oxide, dicumyl peroxide, cyclohexanone peroxide, tert-butylcumyl peroxide, 2,
Examples include 5-dimethylhexane-2,5-cybidrobar oxide. These organic peroxides may be used alone or in combination of two or more.

The blending ratio of the polyolefin resin, modifier, and organic peroxide varies depending on the desired MFR (melt flow rate index) of the modified polyolefin, but generally, based on 100 parts by weight of the polyolefin resin, The modifier is 0.01 to 5 parts by weight, especially o, i to 3 parts by weight, and the organic peroxide is 0.01 to 5 parts by weight, especially 0.1
A range of 2 parts by weight is preferred.

In addition, the blending ratio of the modifier and organic peroxide is as follows: modifier 1
00 parts by weight, the organic peroxide is preferably in the range of 5 to 80 parts by weight.

The modified polyolefin used in the present invention is prepared by mixing a polyolefin resin, a modifier, and an organic peroxide in a method known per se, preferably under conditions that do not decompose the organic peroxide, in a known suitable mixing direction. The polyolefin resin, the modifier and the organic peroxide are mixed together and the resulting mixture is heated to a temperature at which the polyolefin resin melts but does not decompose, preferably from about taO to 260°C, especially from about 220°C to
It is obtained by heating to a temperature of 250°C and causing a graft reaction. The simplest heat treatment operation is to melt and heat the mixture in an extruder at the above temperature for about 2 to 5 minutes. Further, the graft reaction may be performed in an organic solvent.

In addition, the unmodified polyolefin resin used in this invention (
Examples of b) include the aforementioned polyolefin resins. In particular, the same type as that used to obtain the modified polyolefin is preferably used. In particular, the above-mentioned crystalline propylene polymer is preferably used as the unmodified polyolefin resin. Unmodified polyolefin resins include
Calcium anthrax, inorganic substances, and modified polyolefins, which may be blended with conventionally known additives (antioxidants, ultraviolet absorbers, etc.), may be used in the form of master batches of unmodified polyolefin resins.

As the elastomer (c) used in the present invention, a polymer having a lower tensile modulus (ASTMD-882-73) at room temperature than modified or unmodified polyolefin polymers is used.

Specifically, various polyethylenes, ethylene/propylene, ethylene/propylene/diene, ethylene/acrylic acid, ethylene/phthene, ethylene/ethyl acrylate, ionomers, ethylene vinyl acetate, styrene/butadiene copolymers, and liquid rubbers. , and these include unsaturated acids and esters.

It is also possible to use derivatives such as metal salts, imides and amides, and those that have been addition-modified with unsaturated silane compounds and those that have been partially crosslinked. Among these, for crystalline polypropylene, ethylene/propylene/(diene)
Rubber or a modified version thereof is preferred.

Further, when using this unmodified elastomer, polyamide, polyester ether amide, polyester amide, polyether amide, etc. which are compatible with this elastomer can be used in combination.

Calcium carbonate (heavy, light) (d) used in the present invention has an average particle size of 0.05 to ioL, particularly 0.5 to 5IL,
Specific surface area is 0.1 to 100 m'/g.

Particularly preferred is a powder of 1 to 30 m'' and 7 g.

Preferably, calcium carbonate is not surface-treated.

Inorganic substances (e) other than calcium carbonate used in the present invention
Examples include metals such as tar, mica, carbon black, metal powder, carbon fiber, and silicon oxide, silicon carbonates, hydroxides, and oxides, and processed and transformed fibrous materials of these materials. Although these inorganic substances, including , are not effective in improving adhesion, they are effective in damping vibration.

In the adhesive polyolefin composition of the present invention, the blending ratio of each component is (a): 10 to 95% by weight of the modified polyolefin, (b): O to 85% by weight of the unmodified polyolefin, preferably 10% by weight of the unmodified polyolefin. ~85% by weight, (c)
: Elastomer 5-60% by weight, based on the total composition weight (a)
The total of (b) and (c) is 50 to 90% by weight, (d)
: Calcium carbonate 5-50% by weight, (e): Inorganic substances excluding calcium carbonate 0-45% by weight, Obtained by mixing (d) and (e) so that the total is 10-50% by weight. Can be done. If the ratio of each component is outside the above range, the adhesiveness, FrI# thermal properties, or vibration damping properties of the resulting composition will decrease.

The adhesive polyolefin composition of the present invention may include various additives, such as weathering (thermal) stabilizers, molding aids, etc., when mixing each component.The simplest mixing operation is to and are melt-mixed in an extruder at a temperature of about 180 to 260°C, particularly 220 to 250°C, for about 1 to 10 minutes. Examples of the extruder include a single-screw or twin-screw extruder and a continuous mixer such as FCM. The effect of the present invention is further improved by performing a deaeration operation (venting) during melt-mixing. This is because there is moisture attached to the surface of the powdered inorganic substance.

By mixing each of the components (a) to (e) in the above-mentioned specific proportions, the composition of the present invention has greater adhesive strength to a metal sheet than conventionally known polyolefin resin adhesives. If the blending ratio of each component in the composition is outside the above range, the adhesion will be poor. It is not possible to obtain a composition having good properties, bending properties, and heat shock resistance.

There are no particular limitations on the method for obtaining a thin battery using the above composition as a sealing material. A thin battery with excellent sealing performance can be obtained by sandwiching the laminate between the peripheral edges of a pair of laminated thin metal exterior plates and bonding them under heat. Further, the sheet or film can also be used as a three-layer sheet or a three-layer film in which the composition of the present invention is used as an adhesive layer and an intermediate layer made of an unmodified resin is provided in the middle.

[Example of the present invention] Next, examples and comparative examples will be shown.

In the following description, parts indicate parts by weight, and melt flow rate (MFR) was measured according to ASTM D 1238. In addition, long-term storage stability is determined by leaving it for 60 days after manufacture.
Afterwards, a constant current discharge test of 200 gA was conducted.

The bending property test is based on the IC card bending strength measurement method (
DP7816/1), that is, the movable part was repeatedly moved left and right so that the amount of deflection shown in FIG. 1 was 0 to 3 mm.

The adhesive compositions of Examples and Comparative Examples are collectively shown in Table 1.

[Example 1] (Method for creating a sealing material sheet) Ethylene-propylene block copolymer (MFRll,
0g/10min, ethylene content 3% by weight, melting temperature approx. 16
0°C, tensile modulus 14.200 Kg/m”) (7) Irganox l as an antioxidant was added to 100 parts of powder.
010 (Musashino Geigy) 0.1 part, Antiox S (NOF) 0.2 part, calcium stearate 0.05 part, γ-methacryloyloxypropyltrimethoxysilane as a modifier 0.5 part, and organic peroxide. Tertiary butyl peroxybenzoate as a substance 0.25
After mixing for 10 minutes with a Henschel mixer,
0mmφ - 2 minutes at 240℃ (residence time) using axial extrusion
Melt and heat to react, and MFR of about 2mmφ x 3mm
Pellets of modified polypropylene weighing 22 g/10 min were obtained. This pellet and calcium carbonate (Whiten SSB Red, average particle size 1.25IL, specific surface area 1.85rn"7g
, Shiraishi calcium) and ethylene-propylene block copolymer (MFRl, Og/l 0 min, ethylene content 8% by weight, melting temperature 160°C, tensile modulus 14.200
Kg/m”) (7) Pellets (contains a known antioxidant, calcium stearate) and ethylene-propylene copolymer rubber [Japan Synthetic Rubber ■, EP-02P,
tensile modulus of elasticity 80 K g/c rn') in the proportions shown in Table 1, mixed in a blender, and then 50 mm
The mixture was melt-kneaded for 2 minutes at 250° C. using a φ vent-type shaft extruder to obtain pellets of the adhesive polyolefin composition having a size of approximately 2 mm φ x 3 mm. An adhesive polyolefin sheet was prepared from this.

From this sheet, a circular sealing material sheet having an outer diameter of 40 mm x 40 mm and a width of 4 mm was created using a punching blade.

(Creation method of positive electrode mixture) Manganese dioxide 332.9 mg, acetylene black 6
2, 4mgc7) mixture, methoxypolyethylene glycol monoacrylate (AM-90G manufactured by Shin Nakamura Chemical Co., Ltd.)
) 3.1.4 mg, 10.7 mg of polyethylene glycol dimethacrylate (9G manufactured by Shin Nakamura Chemical), and lithium perchlorate dissolved in dimethoxy polyethylene glycol (LX-521 manufactured by Asahi Denka) (m degree 0.75 m mat
/l) 62.8 mg of the solution and 0.067 mg of benzoyl peroxide were further mixed to prepare a positive electrode mixture.

(Creation method of positive electrode) As a positive electrode current collector and exterior plate, the dimensions are 40X40X0.0
Place the above positive electrode mixture on a 5mm stainless steel foil in a 28x28
It was applied uniformly to a size of mm.

This was pressure-molded and heated at 100°C for 3 hours to form a positive electrode plate (
A positive electrode laminate A was prepared, which consisted of a 300° C.m thickness) and an exterior plate.

(Method for creating negative electrode and electrolyte diaphragm) As a negative electrode current collector and exterior plate, the dimensions are 40 x 40 x 0.0.
5mm stainless steel foil, dimensions 26 x 26 x O,
'07mm lithium foil was crimped.

18.4 mg of AM-90G as an electrolyte composition
, 6.0 mg of 9G, lithium perchlorate LX-521
A mixed solution of 25.6 mg of a solution (concentration 0, 75 mol/41) dissolved in 2.2-dimethoxyacetophenone as a photosensitizer was prepared. 8 mL of this electrolyte solution was applied to the lithium metal disk, and irradiated for 3 minutes at an illuminance of 5 mW/cm using a 250 W ultra-high pressure mercury lamp to form a cured film with a thickness of 50 ILm, which served as a current collector and exterior. A laminate B of a plate, a negative electrode, and an electrolyte diaphragm was created.

(Battery assembly) The above laminates A and B were stacked, the annular sealing sheet was sandwiched between the outer periphery of the outer plate, and heat and pressure bonded (180°C, 3
K g/cm'' for 3 minutes) to assemble a thin battery.

The results of the battery discharge test are shown in FIG. 2 below.

In addition, regarding battery ■, bending test 5.000
No abnormality was observed in the sealed portion or electrical properties even after the test.

[Example 2] Instead of EPH in Example 1, polyethylene [manufactured by Ube Industries, Ltd., F222, tensile modulus 1200 Kg/crrf]
) (PE) was used, but a thin battery (2) was assembled in the same manner as in Example 1.

Note that the bending test results for battery (■) were the same as in Example 1.

[Example 3] A thin battery (2) was assembled in the same manner as in Example 2, except that unmodified polypropylene was not used and talc was used as the inorganic substance.

Note that the bending test results for battery (■) were the same as in Example 1.

[Example 4] Example 2 except that ethylene/propylene/diene copolymer [manufactured by Japan Synthetic Rubber ■, EP57F, tensile modulus of elasticity 80 Kg/crn'] (Epoi) was used instead of EPH in Example 1. A thin battery ■ was assembled in the same manner.

Note that the bending test results for battery (■) were the same as in Example 1.

Comparative Example 1 A thin battery O was assembled in the same manner as in Example 1, except that unmodified polypropylene was used instead of modified polypropylene.

In addition, when a bending test was performed on battery (2), peeling was observed at the sealing part after 1.200 cycles.

(Margin below)

[Brief explanation of the drawing]

The t51 diagram shows the method of testing bending characteristics in the present invention. FIG. 2 is a characteristic diagram showing the results of a battery discharge test of a thin battery according to the present invention, and ■ is a characteristic diagram showing the results of a battery discharge test of a thin battery according to the present invention.
(■) of the thin battery according to Example 2, (■) of the thin battery according to Example 2
20% of the thin battery according to Example 3, 2) the thin battery according to Example 4, and 20% of the thin battery according to Comparative Example 1.
0ILA constant current discharge test results.

Claims (1)

[Claims] A separator containing an electrolyte or a solid electrolyte diaphragm is formed between the positive electrode and the negative electrode inside an exterior plate made of a pair of opposing thin metal plates that also serves as a current collector, and the periphery of the exterior plate is A thin battery sealed with a sealing material, the sealing material containing at least three of the following components (a) to (e), the blending ratio of each component being based on the weight of the polymer. (a) is 10-95% by weight, (b) is 0-85% by weight
, (c) is 5 to 60% by weight, and (a
), (b) and (c) in a total of 50 to 90% by weight, (d
) is 5 to 50% by weight, (e) is 0 to 45% by weight, (d)
A thin battery characterized by using an adhesive polyolefin composition in which the total amount of (e) is 10 to 50% by weight. (a) A modified polyolefin obtained by grafting a polyolefin with an organosilane compound having an ethylenically unsaturated bond or an unsaturated compound having a polar group (b) An unmodified polyolefin (c) An elastomer (d) Calcium carbonate ( e) Inorganic substances except calcium carbonate