JPS6326508B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to improvements in cathode and anode current collectors for thin batteries. The current collector of conventional thin batteries is made by pasting a conductive carbon-containing film on a steel foil obtained by rolling a copper plate. However, the thickness of the conventional rolled steel foil is limited to 50 μm, and it has not been possible to roll the foil thinner than that. Furthermore, the rolling process caused an increase in hardness and caused directional properties in the mechanical properties. When this rolled steel foil is used as a current collector for a thin battery, it does not fit well in the sealing part, and when the heat-fusible resin used for the seal during high-temperature storage softens, the rolled steel foil warps and bends over the battery seal. Failures often occurred. Furthermore, even if the rolled steel foil is sufficiently degreased, the surface is mirror-finished, so the carbon film may partially peel off during battery storage, leading to variations in battery performance and leakage. It had the disadvantage of In addition, conventionally, as in JP-A-51-136535, a porous thin foil is electrodeposited on an electrode plate with a roughened surface, peeled off from the electrode plate, and used as an electrode substrate of a battery or its core. However, since the surface of the electrode body is actually rough, the porous thin foil is tightly adhered to it, making it difficult to peel off and causing the porous thin foil to tear or break during peeling. The dot was hot. There was also a method of melting the electrode plate, but it required a long time to melt and had the disadvantage of being extremely inefficient. Furthermore, when iron is used as the metal, it rusts during storage, making it impossible to use it as a cathode/anode current collector that also serves as an external terminal board. The present invention uses inexpensive iron by plating the surface of an ultra-thin iron sheet obtained by plating to prevent rust, and then attaching a conductive carbon film to use as a cathode and anode current collector. The purpose is to improve the storage performance of batteries by improving sealing defects and peeling of the conductive carbon film. A thin battery according to an embodiment of the present invention will be explained in detail based on the drawings. An electrode plate with a flat surface is immersed in an electrolytic plating solution containing iron ions, and metallic iron is electrolytically deposited on the surface of the electrode plate. Electrodeposited iron sheet 1 is approximately 30μm to 50μm
When it reaches a thickness of m, it is washed, then plated with nickel to a thickness of about 2 to 3 m, washed and dried, and peeled off from the electrode plate. Further, a conductive carbon film 2 is closely attached to the nickel plated surface of the iron sheet 1. These are designated as a cathode current collector 3 and an anode current collector 4. Furthermore, the cathode body 5 made of a thin zinc plate is crimped onto the two surfaces of the conductive carbon film of the cathode current collector 3, and the anode current collector 2 is
90% manganese dioxide by weight on two conductive carbon films.
A dispersion of 10% by weight of carbon black is applied and dried. Next, the periphery of the separator 7 is impregnated with a heat-fusible resin 8 made of polyamide resin, and the ammonium chloride electrolyte is retained throughout the separator 7 except for the periphery. The cathode body 5 and the anode body 6 are stacked facing each other with the separator 7 interposed therebetween, and the peripheral portion of the battery is thermocompressed and sealed with a heat-fusible resin 8 to produce a thin battery. The iron sheet 1 used for the cathode and anode current collectors 3 and 4 of the battery of the present invention is an ultrathin plate obtained by electrolytic plating method in which iron ion solution is electrolytically deposited, and nickel-plated iron is peeled off from a plated electrode plate with a flat surface. and has a thickness of about 30 μm to 50 μm, and has the advantages listed in Table 1 for thin batteries compared to conventional rolled steel foil.

[Table] As shown in Table 1, the iron sheet 1 according to the present invention is highly flexible and has a nickel plated surface to prevent rust, and a conductive carbon film 2 is pasted to form the cathode and anode current collectors 3 and 4. Since the iron sheet 1 has good flexibility when the battery is heat-press sealed with the heat-fusible resin 8, it fits better at the sealing part compared to rolled steel foil, and the heat-fusible resin 8 does not melt during high-temperature storage. Even if the plastic resin 8 softens, a sufficiently tight seal can be maintained. In addition, since the iron sheet 1 of the present invention is plated into an electrode body with a flat surface, the surface roughness differs between the electrode surface and the plated surface, and the surface in contact with the electrode plate is flat, but the plated surface has a large surface roughness, and has a significantly strong interference effect with the conductive carbon film 2, making it possible to adhere more firmly to the conductive carbon film 2 than with the mirror surface of conventional rolled steel foil. . Furthermore, the iron sheet 1 of the present invention can be plated with tin, zinc, or copper in addition to nickel for anti-rust surface treatment, or chromate treatment to form a corrosion-resistant film of chromic acid on the surface. Since no rust occurs, it is effective in preventing peeling of the conductive carbon film 2. Next, using the iron sheet 1 of the present invention, the size is 40 mm.
Inventive product of thin battery with ×70 mm and thickness of 0.7 mm [A]
and a conventional product of the same shape using conventional rolled steel foil [B]
were stored at a temperature of 60°C for one month, and the rate of leakage for each 100 pieces was calculated. are summarized in Table 2.

[Table] As shown in Table 2, the product of the present invention has a more flexible battery compared to conventional products, so there is less leakage due to poor sealing, and separation of the conductive carbon film 2 and separator due to leakage. Since there is no drying as described in No. 7, the discharge performance after storage is excellent. As described above, a thin battery in which a conductive carbon film is formed on one side of an iron sheet obtained by the electrolytic plating method and used as a cathode/anode current collector has a high leakage performance after storage,
The discharge performance is greatly improved.

[Brief explanation of the drawing]

The figure is a sectional view of a thin battery according to an embodiment of the present invention. 1... Iron sheet, 2... Conductive carbon film, 3...
Cathode current collector, 4... Anode current collector.

Claims (1)

[Claims] 1. An iron sheet 1 is formed by electrolytically plating an iron ion-containing solution on an electrode plate with a flat surface, and the surface is plated with nickel, tin, zinc or copper,
After washing and drying, the iron sheet 1 is peeled off from the electrode plate, and a conductive carbon film 2 is closely attached to the plated surface of the iron sheet 1 to form a cathode current collector 3 and an anode current collector 4. A cathode body 5 made of zinc is crimped onto two surfaces of the carbon film, an anode body 6 made of manganese dioxide is closely attached to the two surfaces of the conductive carbon film of the anode current collector 4, and the cathode body 5 and the anode body are bonded through a separator 7. A method for producing a thin battery, characterized by stacking the battery cells 6 and 6 facing each other, and sealing the periphery with a heat-fusible resin 8.