JPS6326507B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an improvement in the manufacturing method of metal current collectors for thin batteries, and its purpose is to improve the discharge performance and storage performance of batteries by applying a conductive and heat-fusible adhesive with excellent adhesion. do. The metal current collector of conventional thin batteries is a metal plate made of iron, aluminum, zinc, stainless steel, copper, etc., resin such as vinyl chloride, melamine, epoxy, phenol, etc., and carbon such as graphite, acetylene black, etc. as a conductive material. A conductive adhesive prepared by dissolving and mixing powder with a solvent was applied and dried to be used in thin batteries. However, conductive adhesives whose main component is vinyl chloride resin have poor adhesion to metal plates and peel off during long-term storage, forming an electrically insulating layer that increases the battery's internal resistance and reduces discharge performance. Otherwise, the electrolyte penetrated between the metal plate and the adhesive film, causing an internal short circuit in the battery. In addition, to improve this drawback, conventionally melamine,
Conductive adhesives have been developed whose main ingredients are thermosetting resins such as epoxy and phenolic resins.
Although it has good adhesion to metal plates, it requires heat curing at high temperatures for a long time, has poor workability and poor conductivity, and is also unsuitable for thermocompression bonding of carbon films and the like. The present invention improves the conventional drawbacks by directly applying a conductive and heat-adhesive adhesive mainly composed of saturated copolymerized polyester resin to one side of the metal foil, thereby improving its adhesion to the metal foil. This improves the discharge performance and storage performance of the battery. A thin battery according to an embodiment of the present invention will be explained based on the drawings. As shown in Figure 2 A, 1 is a metal foil made of a corrosion-resistant metal such as nickel, iron, aluminum, stainless steel, etc., whose outer surface also serves as a cathode terminal 10, and a conductive/thermal adhesive 2 is directly applied to the inner surface. After drying, a carbon film 3 was bonded to the adhesive 2 by heat-pressing.
A cathode metal current collector 4 consisting of layers is formed. Next, as shown in FIG. 1, numeral 5 denotes a cathode made of a thin zinc plate, which is formed slightly smaller than the carbon film 3 and collects current in close contact with the carbon film 3. Reference numeral 6 denotes a separator made of kraft paper, synthetic paper, etc., which is in close contact with the cathode 5, and is sealed with a sealant 7 such as an epoxy resin type impregnated or painted on the periphery of the separator 6.
The battery is sealed tightly. Reference numeral 8 denotes a cathode metal current collector, which has a metal foil whose outer surface also serves as an anode terminal 11, has a conductive/heat-fusible adhesive 2 applied directly to the inner surface, and is further coated with a carbon film. This carbon film is coated with an anode mixture 9 consisting mainly of manganese dioxide powder, which is an anode active material, and acetylene black, which is a conductive material, and polyvinyl alcohol or polyacrylic acid, which is a binder. Power is being collected.
A separator 6 is sandwiched between the anode mixture 9 and the cathode 5, and the cathode and anode metal current collectors 4 and 8 are stacked so that the terminals are on the outside.
Except for this, it is covered with an exterior body 12 laminated with synthetic resin or metal. Note that the separator 6 and the anode mixture 9 contain an electrolytic solution consisting of, for example, an aqueous zinc chloride solution or a mixed aqueous solution of zinc chloride and ammonium chloride. The cathode and anode metal current collectors 4 and 8 used in the thin battery of the present invention, as shown in FIG. A conductive/thermal adhesive 2 made by dissolving and mixing a saturated copolymerized polyester resin synthesized from alcohol and carbon powder such as graphite or acetylene black in a solvent is applied directly to the inner surface of the metal foil 1 and dried. Furthermore, a carbon film 3 is bonded to the surface of the adhesive 2 by heat-pressing. Since the cathode and anode metal current collectors 4 and 8 of the battery of the present invention are bonded together using the adhesive 2 whose main component is a saturated copolymerized polyester resin, they have good heat resistance, impact resistance,
Polyester has excellent bending resistance, has good adhesion between the metal foil and the adhesive 2, and is used as a component of the exterior body 12 and carbon film 3 that cover the battery.
It has excellent adhesion to resins such as polyvinyl chloride and polycarbonate, and also functions as a heat-fusible adhesive. In addition, since the adhesive 2 contains carbon powder and has conductivity, as shown in FIG. The same effect can be obtained with the metal current collector 4' or with a similar two-layered anode current collector. Next, the thin battery of the present invention will be compared with a conventional battery of the same type. First, for the current collector used in the product of the present invention, 15 parts by weight of linear saturated polyester resin, 11 parts by weight of scaly graphite, 4 parts of acetylene black, and 70 parts of methyl ethyl ketone are mixed and dissolved as a conductive and heat-fusible adhesive. A heat-adhesive adhesive 2 is formed and 10 μm is applied to the inner surface of a 50 μm thick iron metal foil 1.
A carbon film 3 with a thickness of 50 μm and mainly composed of vinyl chloride was coated with a thickness of 15 μm and dried at 60°C for 10 minutes to form a non-adhesive film at 10 kg/cm ² at 150°C.
Heat and press the cathode anode metal current collector 4,
form 8. Using these cathode and anode metal current collectors 4 and 8, the above-mentioned thin battery with a size of 40 mm x 70 mm is manufactured.
Inventive product [A] was manufactured by making 160 prototypes. Furthermore, in the product [B] of the present invention, a film is formed from an adhesive 2 similarly using a linear saturated polyester resin, and a cathode metal current collector 4' having a two-layer structure without using a carbon film 3 and a cathode metal current collector 4' having a two-layer structure are formed. Using an anode metal current collector,
160 thin batteries of the same type according to the present invention [B] were manufactured. Next, as a conventional product, an adhesive prepared by weighing and dissolving 15 parts of soluble vinyl chloride resin, 7.5 parts of carbon powder, and 70 parts of solvent was applied to the inner surface of the metal foil, and a cathode and anode metal current collector with the carbon film crimped was applied. We made 160 prototypes of the same type of conventional thin battery [C] that we used,
Furthermore, as a conventional product [D], 160 prototypes were manufactured using thermally crosslinkable melamine resin in the same manner as [C]. These thin batteries of the present invention [A] and [B] with a size of 40 mm x 70 mm and the conventional products [C] and [D]
The open circuit voltage and 500Ω closed circuit voltage of 30 pieces were measured one week after manufacture, and the results were shown in Table 1 after continuous discharge of 500Ω. In addition, 130 pieces were stored at a high temperature of 45℃, and after 3 months, the same open circuit and closed circuit voltages and 500Ω continuous discharge,
We investigated the number of defective batteries with internal short circuits out of 100, and
The results are summarized in Table 2.

【table】

[Table] The results in Table 1 show that the products [A] and [B] of the present invention have a high closed-circuit voltage, and therefore have a low polarization resistance, that is, an internal resistance, and excellent adhesion to the metal current collector.
Furthermore, discharge performance has also been improved. As shown in Table 2, even after storage, the closed circuit voltage is high and the adhesion is maintained, and the discharge performance is also excellent. The thickness of the adhesive 2 is preferably between 5 μm and 300 μm. If it is less than 5 μm, pinholes will be formed and corrosion will occur, the adhesive strength will be weak, and battery short circuits will easily occur. If it exceeds 300 μm, the electrical resistance will decrease. cannot be ignored, and the materials are also wasted and have little practical value.
In addition, the amount of carbon powder added to the adhesive is preferably 0.7 to 1.2 parts by weight per 1 part by weight of the polyester resin.
If it is less than 0.7 parts by weight, the conductivity is poor, and if it exceeds 1.2 parts by weight, the conductivity is sufficient but the adhesion is extremely deteriorated. Furthermore, the metal current collector used in the thin battery of the present invention can also be applied to stacked batteries such as 006P. As described above, the cathode anode is formed by directly coating one side of the saturated copolymerized polyester resin of the present invention synthesized from terephthalic acid and saturated polyhydric alcohol with a conductive and heat-fusible adhesive containing carbon powder. Thin batteries manufactured using metal current collectors have low internal resistance and excellent discharge performance and storage performance.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a thin battery manufactured according to an embodiment of the present invention, A in Figure 2 is an enlarged sectional view of the main part of the cathode metal current collector used in the thin battery, and B is a two-layer implementation. FIG. 3 is an enlarged sectional view of a main part of a cathode metal current collector in an example. 1...Metal foil, 2...Adhesive, 3...Carbon film,
4, 4'... Cathode metal current collector, 8... Anode metal current collector, 10... Cathode terminal, 11... Anode terminal.

Claims (1)

[Claims] 1. A conductive/heat-fusible adhesive 2 made by adding carbon powder to a saturated copolymerized polyester resin synthesized from terephthalic acid and a saturated polyhydric alcohol is applied to one side of a metal foil 1. , and a cathode metal current collector 4 with a cathode terminal 10 on the opposite side, and an anode metal current collector 8 with an adhesive 2 applied on one side of another similar metal foil and an anode terminal 11 on the opposite side. A method for manufacturing a thin battery characterized by assembling it using. 2 The cathode metal current collector 4 or the anode metal current collector 8
2. The method of manufacturing a thin battery according to claim 1, wherein a conductive/heat-fusible adhesive 2 and a carbon film 3 are bonded to the surface of the thin battery.