JPS6041832B2 - Battery manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for increasing the density of an electrolyte used in a battery using a glue material.

Conventional batteries use corn starch, starch, cross-linked starch, etherified starch, cellulose ethers, carboxymethyl cellulose (CM
C), a natural or synthetic adhesive such as polyvinyl alcohol (PVA) or polyvinyl acetal was applied to a kraft paper or nonwoven fabric separator.

However, conventional adhesives hold only a small amount of electrolyte, and as the battery discharges and the zinc chloride concentration increases, the adhesive tries to separate the electrolyte, causing the separator to dry and lowering the battery's internal resistance. This caused the discharge performance and storage performance to deteriorate. In addition, the conventional adhesive reduces manganese dioxide, which is an active material of the battery, during long-term storage or high-temperature storage, resulting in a voltage drop and discharge performance deterioration.

The present invention aims to improve the above-mentioned conventional drawbacks, by adding 0.2 to 8% by weight of acetalized polyvinyl alcohol to an electrolytic solution containing zinc chloride as the main electrolyte and heating it to increase the concentration. By using, the discharge performance of the battery,
The purpose is to improve storage performance.

A thin battery manufactured according to an embodiment of the present invention will be explained with reference to FIG.

In the figure, 1 is a cathode current collector and 2 is an anode current collector.

These bipolar current collectors 1 and 2 are made of corrosion-resistant metal foil 3 made of aluminum, nickel, steel, stainless steel, etc., and the inner surface is coated or sprayed with a binder such as epoxy resin added to carbonaceous material. A carbon film 4 is attached by attaching or the like. Reference numeral 5 denotes a thin layer cathode body made of a cathode active material such as zinc foil or zinc powder, which is in close contact with the carbon film 4 of the cathode current collector 1 .

For example, 6 is an anode body made mainly of manganese dioxide powder I as an active material, acetylene black as a conductive material, and polyacrylic acid as a binder. The film is adhered in a thin layer by, for example, screen printing or roller coating. This cathode body 5 and anode body 6
A separator 7 made of a nonwoven fabric of polyethylene fibers and polyester fibers is clamped between the An electrolytic solution 8 is held. In this example, 3% by weight of acetalized polyvinyl alcohol fibers were mixed in a 25% zinc chloride solution, and the mixture was heated at 90°C to dissolve and thicken the acetalized polyvinyl alcohol at high temperature. I am using it. This takes advantage of the property that acetalized polyvinyl alcohol dissolves in hot zinc chloride solution and thickens, but does not dissolve in aluminum chloride solution. Since the electrolytic solution 8 thickened by the polyvinyl alcohol is firmly held between the cathode body 5 and the anode body 6, there is no way for the electrolytic solution 8 to separate, and therefore no more than necessary Since the electrolyte 8 is not transferred to the anode body 6 and the separator 7 is not dried, there is little variation in discharge performance that increases the internal resistance of the battery. Next, an anode body was made by adding 1 part of the glue material to 1 part of manganese dioxide using each of the conventional glue materials and the polyvinyl alcohol for acetal used as the glue material in the present invention.
It was immersed in a 25% zinc chloride solution at a temperature of 60° C. for an hour, and the potential deterioration was measured and summarized in Table 1.

11 As a result of Table 1, since the present invention acetalizes polyvinyl alcohol (PVP), there is almost no reduction deterioration of manganese dioxide, and compared to batteries using PVA, it is possible to maintain a stable battery voltage during long-term storage. .

The present invention uses acetalized polyvinyl alcohol as a glue material to thicken the zinc chloride electrolyte 8, and is not used as a separator 7 material.

Therefore, in the present invention, a non-woven fabric made of polyethylene or polyester fiber is used for the separator 7, and the electrolyte 8 thickened with acetalized polyvinyl alcohol having a degree of acetalization of 17% or more as a glue material is held therein. A high-performance battery is obtained by utilizing the solubility of the adhesive in hot zinc chloride electrolyte 8 and the stability with respect to manganese dioxide. Furthermore, when the zinc chloride concentration of the electrolytic solution 8 is in the range of 15 to 35%, the solubility of the glue material is large and the thickening effect is excellent, and
The amount of the glue added is preferably in the range of 0.2 to 8% with respect to the electrolytic solution 8. If it is less than 0.2%, the viscosity will be weak, and if it exceeds 8%, the resistance of the electrolytic solution 8 will be increased. Next, 40W$L×
In a thin battery with a size of 7" and a thickness of 0.7", 2
The product of the present invention [A], which was thickened by adding 3% acetalized polyvinyl alcohol to 5% zinc chloride electrolyte 8, and the conventional product [B], which was thickened with polyvinyl alcohol.
The samples were stored at 45°C for 3 months, and a comparison of the discharge curves of 5 pieces each at 20°C and 1KΩ is shown in Figure 2.

As a result, it can be seen that the product of the present invention has excellent discharge operating voltage and duration after storage. As described above, the present invention prevents reductive deterioration of the anode active material by mixing 0.2 to 8% by weight of acetalized polyvinyl alcohol to a zinc chloride electrolyte and heating the mixture to increase the viscosity. , the storage performance of the battery can be greatly improved.

[Brief explanation of the drawing]

FIG. 1 shows a thin battery as an example manufactured according to the present invention, and FIG. 2 is a comparison diagram of discharge curves between the product [A] of the present invention and the conventional product [B]. 6... Anode body, 7... Separator, 8
・・・・・・Electrolyte.

Claims (1)

[Claims] 1. In a method for manufacturing a battery consisting of an anode active material mainly consisting of manganese dioxide, an electrolyte solution consisting of zinc chloride, and a cathode active material mainly consisting of zinc,
A method for manufacturing a battery, characterized by mixing ~8% by weight of acetalized polyvinyl alcohol and heating to dissolve and thicken the mixture.