JPH0665041B2 - Sheet-shaped battery and manufacturing method thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a sheet-like battery and a method for producing the same, and particularly to a sheet-like battery in which a short circuit of electrodes during production is prevented and the sheet-like battery is continuously produced. Regarding the method.

[Prior Art] In recent years, with the remarkable development of electronic devices, downsizing, weight reduction, and thinning of devices have been attempted. Among them, sheet batteries (thin batteries, button batteries) play an important role as power sources for cameras, thin radios, card calculators, IC cards and the like.

Conventionally, in this type of sheet battery, a positive electrode, a positive electrode mixture, a separator, in a case made of a pair of aluminum foils,
A negative electrode mixture, a negative electrode, etc. are stored. This case is sealed to prevent liquid leakage, but as a means for that, a method of laminating polyethylene on the entire surface of a metal foil such as a pair of aluminum foil or stainless steel foil, which is a case, and sealing the peripheral portions by heat welding, Alternatively, a method is known in which at least one peripheral edge of the pair of metal foils is laminated with polyethylene, and similarly the peripheral edges are sealed by heat welding.

However, in the former case, for example, an aluminum foil having polyethylene laminated on the entire surface is used as a case, and a lead connecting a positive electrode and a negative electrode is exposed to the outside. In the case of this sheet-shaped battery, the leads that will be the electrodes are sandwiched between the aluminum foils, and the polyethylene on the inner peripheral edge is heat-welded to seal it. However, when the polyethylene is welded, the aluminum foil and the leads are easily short-circuited. There is.

Further, as an example of the latter, there is one in which the case metal also serves as a lead. That is, only the peripheral portion of the metal foil plate such as aluminum foil or stainless steel foil, which is a case, having a width of about 5 mm is laminated with polyethylene, and expanded metal is spot-welded to the inner peripheral portion which is not laminated, and the electrode is directly fixed thereto. To do. In this case as well, the case metals, which also serve as leads, have a drawback that they are likely to come into contact with each other during welding of polyethylene.

[Problems to be Solved by the Invention] The present invention has been made in order to solve the drawbacks of the above-described conventional example, and a first object of the present invention is to eliminate a short circuit of electrodes which occurs at the time of sealing and to achieve complete sealing. The present invention provides a sheet-shaped battery that can be used.

A second object of the present invention is to provide a method of continuously filling a positive electrode mixture, a separator, and a negative electrode mixture without short-circuiting electrodes to continuously produce a sheet-shaped battery.

[Means and Actions for Solving Problems] In order to achieve the above object, the sheet-shaped battery of the present invention comprises:
Both sides of the thermoplastic resin have a lower melting point than the thermoplastic resin,
In addition, an ethylene copolymer modified with an unsaturated carboxylic acid or a derivative thereof or a laminated sheet in which a composition containing the ethylene copolymer is laminated is provided, and an electrolytic solution provided between a pair of sheet electrodes and the pair of electrodes is provided. It is characterized in that it is interposed in the peripheral portion of the sheet-like battery provided with a holding separator.

The preferred method for producing the sheet-shaped battery of the present invention is as follows.

That is, the method for producing a sheet-shaped battery of the present invention comprises, on both surfaces of a thermoplastic resin, an ethylene copolymer having a melting point lower than that of the thermoplastic resin and modified with an unsaturated carboxylic acid or a derivative thereof, or the ethylene copolymer. Laminating a composition containing a coalescence, to obtain a laminated sheet provided with a cutout portion leaving the peripheral portion of the obtained laminated body, while continuously feeding this,
At the same time, the metal foil was continuously fed out to the bottom surface, the cutout portion was filled with the positive electrode mixture, the separator, and the negative electrode mixture, and the upper surface was laminated with the metal foil, and then the laminated sheet was heat-welded and sealed. It is characterized by

Hereinafter, the present invention will be described in more detail.

The thermoplastic resin used in the present invention includes low-medium-high density polyethylene, polypropylene, polybutene-1, homopolymers such as poly-4-methylpentene-1, and other α containing ethylene or propylene as a main component. -Olefin copolymers such as olefin copolymers, polyamide polymers such as nylon 6, nylon 6,6, nylon 1, 2, etc., polycarbonate polymers, polyester polymers and the like.

Further, in the present invention, an ethylene copolymer having a melting point lower than that of the thermoplastic resin and modified with an unsaturated carboxylic acid or a derivative thereof, or a composition containing the ethylene copolymer is laminated on both surfaces of the thermoplastic resin. The laminated sheet is heat-sealed and used as a sealing material.The ethylene copolymer used here is an ethylene-α-olefin copolymer or ethylene-vinyl acetate copolymer having a density of 0.86 to 0.94 g / cm ³ , and ethylene. -Ethylene copolymers such as ethyl acrylate copolymers or mixtures thereof are used. The ethylene-α-olefin copolymer here is an α-olefin copolymer having 3 to 12 carbon atoms with ethylene. Specific α-olefins include propylene, butene-1, 4-methylpentene-1, hexene-
1, octene-1, decene-1, dodecene-1 and the like. Of these, propylene and butene-1 are particularly preferable. The α-olefin content in the ethylene-α-olefin copolymer is preferably 5 to 40 mol%.

Examples of the unsaturated carboxylic acid used here include monobasic acids and dibasic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid and citraconic acid. Examples of unsaturated carboxylic acid derivatives include metal salts, amides, imides, esters, and anhydrides of the above unsaturated carboxylic acids. Of these, maleic anhydride is most preferable.

The unsaturated carboxylic acid or its derivative (hereinafter, referred to as unsaturated carboxylic acids) is added in an amount of 0.01 to 5.0% by weight of the unsaturated carboxylic acid with respect to the ethylene copolymer or the composition containing the ethylene copolymer. , Preferably 0.1-3.0
% By weight is added and the reaction is generated by heating in the presence of an organic peroxide.

The reaction is carried out by melting and mixing in an extruder or a kneader such as a Banbury mixer in the absence of a solvent to cause a reaction, or an aromatic hydrocarbon such as benzene, xylene and toluene, and an aliphatic hydrocarbon such as hexene, heptane and octane. There is a method of heating and mixing in a solvent such as, and is not particularly limited, but it can be carried out in the extruder because of its simple operation, excellent economical efficiency, continuity with subsequent steps, etc. preferable.

When the amount of the unsaturated carboxylic acids exceeds 5.0% by weight, decomposition and crosslinking reactions may occur in addition to the addition reaction,
If it is less than 0.01% by weight, sufficient adhesiveness cannot be obtained.

Examples of the organic peroxide include benzoyl peroxide, lauryl peroxide, azobisisobutyronitrile, dicumyl peroxide, t-butyl hydroperoxide, α, α′-bis (t-butylperoxydiisopropyl). Benzene, di-t-butylperoxide, 2,5-di (t-butylperoxy) hexine and the like are preferably used, and are used per 100 parts by weight of the ethylene copolymer or a composition containing the ethylene copolymer. , 0.005 ~
It is used in an amount of 2.0 parts by weight, preferably 0.01 to 0.1 parts by weight. When the amount of the organic peroxide added is less than 0.005 parts by weight, the modifying effect is not substantially exerted, and it is difficult to obtain a further effect even if added in excess of 2.0 parts by weight, This may cause decomposition or crosslinking reaction.

Hereinafter, the sheet battery and the method for manufacturing the same according to the present invention will be specifically described with reference to the drawings.

FIG. 1 is a schematic partial sectional view showing an embodiment of the sheet-shaped battery of the present invention.

In FIG. 1, 1 is a center layer, 2 is a surface layer, 3 is a laminated sheet, 4 and 4'are metal foils (aluminum foil or stainless steel foil), 5 are separators, 6 is expanded metal,
Reference numeral 7 represents a positive electrode mixture (lithium), and 8 represents a negative electrode mixture (polyacetylene).

In the sheet-shaped battery of the present invention, the laminated sheet 3 including the central layer 1 and the surface layers 2 laminated on both surfaces of the central layer 1 is used as a sealing material interposed in the peripheral portion of the battery. The center layer 1 is made of a thermoplastic resin, and the surface layer 2 is the center layer 1.
Which has a lower melting point than the thermoplastic resin and is modified with an unsaturated carboxylic acid such as maleic anhydride, or an ethylene copolymer or a composition containing the ethylene copolymer.

This laminated sheet 3 has a shape as shown in FIG. 3 in which a peripheral portion is left and a cutout portion is provided from a laminated body 9 as shown in FIG. 2 obtained by laminating the center layer 1 and the surface layer 2. Of the sheet-shaped battery without causing a short circuit of the electrodes,
It is desirable from the viewpoint of smooth and continuous production.

In order to seal a sheet-like battery using the sealing material composed of this laminated sheet 3, the laminated sheet 3 is interposed in the sealing portion of the conventional sheet-like battery, and the sealed portion is lower than the melting point of the center layer 1 and the surface layer. Heat under pressure at a temperature above the melting point of 2. When heated at a temperature within this range, the laminated sheet 3
It is possible to melt only the surface layer 2 and to further fill the gap in the sealed portion by the pressing force. On the other hand, since the melting point of the center layer 1 is higher than the heating temperature, the center layer 1 does not melt, the case that also serves as the electrode is prevented from short-circuiting, and complete sealing is possible.

The thickness of the surface layer 2 of the laminated sheet is preferably in the range of about 5 to 200 μm, and the thickness of the central layer 1 is preferably in the range of about 30 to 800 μm.

In the case of using the laminated sheet 3 as shown in FIG. 3, while continuously feeding the laminated sheet 3, the metal foil 4 also serving as a lead is continuously fed to the bottom surface thereof.
The cutout portion is filled with the positive electrode mixture 7, the separator 5, and the negative electrode mixture 8, and the metal foil 4 ′ also serving as the other lead is attached to the upper surface, and then laminated on the upper and lower metal foils 4 and 4 ′. The sheet-shaped battery can be continuously manufactured by heat-sealing and sealing the sheet 3.

FIG. 4 is a schematic partial cross-sectional view showing another embodiment of the sheet battery of the present invention. The sheet-like battery shown in FIG. 1 uses a metal foil laminated with polyethylene on the entire surface as a case in the above-mentioned conventional example, and the sheet-like battery shown in FIGS. The laminated sheet 3 shown in FIG. In FIG. 4, the same parts as those of the sheet-shaped battery shown in FIG. 1 are designated by the same reference numerals. An insulating material 9 made of polyethylene is laminated on the entire inner surfaces of the metal foils 4 and 4 '. Leads 10 and 11 are connected to the expanded metal 6 serving as a positive electrode and a negative electrode. Two-layer laminated sheet 3 interposed between the leads 10 and 11 and the metal foils 4 and 4 '
Is the same as the case of the sheet-shaped battery in FIG.
The metal foils 4 and 4'are prevented from being short-circuited and a perfect seal is possible.

Example 1 Ethylene-butene-1 copolymer (density 0.934 g / cm ³ , melt index 10 g / 10 minutes, trade name: Nisseki Linirex A
Using J5610, manufactured by Nippon Petrochemical Co., Ltd., maleic anhydride 0.25% by weight and organic peroxide (trade name: Perhexin 2,5B, manufactured by NOF Corporation) 0.02% by weight
A 50 mmφ (screw diameter) extruder was used to melt and knead the mixture at a temperature of 230 ° C. to obtain a modified ethylene-butene-1 copolymer. (Hereinafter referred to as MLLDPE) Next, using a multi-layer die, high density polyethylene (density 0.
958 g / cm ³ , melt index 0.3 g / 10 minutes, trade name: Nisseki Staflen E704, manufactured by Nippon Petrochemical Co., Ltd. (hereinafter referred to as HDPE) as an intermediate layer, and the above MLLDPE is used.
Was supplied to a multi-layer die, joined at a die temperature of 220 ° C. in front of the die lip, and laminated to produce a three-layer laminated sheet.

The thickness of the obtained laminated sheet is MLLDPE 25 μm / H
The DPE was 50 μm / MLLDPE was 25 μm.

30mm length x 30mm width and 5mm width of outer edge
It is cut out so that it remains over the entire length, and it is inserted between a high-chromium stainless steel plate of 30 mm in length x 30 mm in width 30 μm and a nickel steel plate of 30 μm, and propylene-carbonate etc. is sealed inside, temperature 200 ℃, pressure 5 kg / cm ³ The sheet-shaped battery was manufactured by heat-bonding for 30 seconds.

The obtained sheet-shaped battery was placed in a constant temperature humidifying tank at 80 ° C. and RH of 95%, and after 10 days, the amount of water permeated into the battery was measured as the water concentration. The results are shown in Table 1.

Examples 2 to 4 The same MLLDPE and HDPE as in Example 1 were used to prepare laminated sheets having different thicknesses as shown in Table 1, and the moisture infiltration amount was measured in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 1 Instead of the laminated sheet of the present invention, an ionomer resin (trade name: Himilan, manufactured by Mitsui DuPont Polychemical Co., Ltd.) was used in a thickness of 200 μm and evaluated in the same manner as in Example 3. The results are shown in Table 1.

As is clear from Table 1, the sheet-shaped batteries of Examples 1 to 4 have better sealing performance than the sheet-shaped battery of Comparative Example 1.

[Effects of the Invention] As described above, the sheet-shaped battery of the present invention can eliminate the short circuit of the electrode that occurs at the time of sealing and can completely seal it. Further, the production method of the present invention can smoothly fill a positive electrode mixture, a separator, and a negative electrode mixture without short-circuiting the electrodes to continuously produce a sheet battery.

[Brief description of drawings]

FIG. 1 is a schematic partial cross-sectional view showing an embodiment of the sheet-shaped battery of the present invention, FIG. 2 is a laminated body used in manufacturing the sheet-shaped battery of the present invention, and FIG. 3 is a sheet-shaped battery of the present invention. FIG. 4 is a schematic sectional view showing another embodiment of the sheet-shaped battery of the present invention, and a laminated sheet used for manufacturing the battery. 1: Central layer, 2: Surface layer, 3: Laminated sheet, 4, 4 ′: Metal foil, 5: Separator, 7: Positive electrode mixture, 8: Negative electrode mixture, 9: Insulating material, 10, 11: Lead.

Claims (5)

[Claims] 1. An ethylene copolymer having a melting point lower than that of the thermoplastic resin and modified with an unsaturated carboxylic acid or a derivative thereof or a composition containing the ethylene copolymer is laminated on both sides of the thermoplastic resin. A sheet-shaped battery, wherein a laminated sheet is interposed in a peripheral portion of a sheet-shaped battery provided with a pair of sheet-shaped electrodes and a separator for holding an electrolytic solution provided between the pair of electrodes. 2. The sheet-shaped battery according to claim 1, wherein the thermoplastic resin is high-density polyethylene. 3. The ethylene copolymer has a density of 0.86 to 0.94 g /
cm ³ ethylene-α-olefin copolymer, ethylene-
The sheet-like battery according to claim 1 or 2, which is selected from a vinyl acetate copolymer, an ethylene-ethyl acrylate copolymer, or a mixture thereof. 4. The sheet battery according to claim 1, 2, or 3, wherein the unsaturated carboxylic acid derivative is maleic anhydride. 5. An ethylene copolymer having a melting point lower than that of the thermoplastic resin and modified with an unsaturated carboxylic acid or a derivative thereof or a composition containing the ethylene copolymer is laminated on both sides of the thermoplastic resin. , To obtain a laminated sheet provided with a cutout portion leaving the peripheral portion of the obtained laminate, while continuously feeding it out, at the same time continuously feeding out a metal foil to the bottom surface thereof, a positive electrode mixture in the cutout portion, A method for producing a sheet battery, comprising filling a separator and a negative electrode mixture, further laminating a metal foil on the upper surface thereof, and then heat-sealing and sealing the laminated sheet.