JPS60230359A - Alkaline battery - Google Patents

Abstract

PURPOSE:To increase leakage resistance of alkaline battery by forming an anode active mix with zinc powder, alkaline electrolyte, and gelling agent of copolymer of acrylic acid and vinyl alcohol. CONSTITUTION:An anode active mix 7 is prepared by kneading 72pts.wt. zinc power having a particle size of 48-150 mesh, and an amalgamation ratio of 7%, 24pts.wt. 40% potassium hydroxide, and 4pts.wt. gelling agent of copolymer of acrylic acid and vinyl alcohol, and filled in an anode case 8. The anode case 8 is combined with a separator 6, a positive catalyst layer 5, a water repellent film 4, and a positive case 1 having air access holes 2, and they are sealed to form a button type zinc air battery. Copolymer of acrylic acid and vinyl alcohol has a property stable to alkaline electrolyte same as sodium acrylate, and also has no stringiness. Therefore, leakage resistance of the battery is substantially increased.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Sedentary Use) The present invention relates to alkaline batteries such as zinc-air batteries, alkaline manganese batteries, and silver batteries, and particularly to improvements in cathode mixtures used in alkaline batteries.

(Prior art) Conventionally, the cathode mixture for alkaline batteries is made by kneading powdered zinc (amalgamated), alkaline electrolysis of calcium hydroxide aqueous solution or sodium hydroxide aqueous solution, and gelling agent of carboxymethyl cellulose or polyacrylic acid soda. was used.

However, when carboxymethyl cellulose is used as a kelizing agent, the carboxymethyl cellulose is decomposed by the alkaline electrolyte during storage of the battery, the viscosity of the zinc cathode decreases, and the zinc powder and the alkaline electrolyte separate from each other. do. Due to this mutual separation, leakage of the electrolyte tended to occur easily.

Therefore, cathode mixtures that use gels that are stable against alkaline electrolytes as gelling agents have the disadvantage of being stringy, making it difficult to fill into the cathode case, and having poor workability. Ta.

(Object of the Invention) In view of the above-mentioned problems, the object of the present invention is to obtain an alkaline battery using a gelling agent that has excellent leakage resistance and allows easy filling of the zinc cathode into the cathode case.

(Structure of the Invention) The present invention is characterized in that a copolymer of acrylic acid and vinyl alcohol is used as the gelling agent in a cathode mixture prepared by kneading powdered zinc, an alkaline electrolyte, and a gelling agent. The main focus is on alkaline batteries.

A copolymer of acrylic acid and vinyl alcohol is obtained by removing the stable properties of sodium polyacrylate in alkaline electrolytes and the stringiness of sodium polyacrylate, and this copolymer can be used as a gelling agent. By using this, the above-mentioned problems can be solved.

(Example) Next, embodiments of the present invention will be described with reference to the drawings.

The example was carried out using a button-type R44 type zinc-air battery. An air inflow hole 2 is provided on the bottom of the positive electrode case 1, which has a flat bottom surface, and an air diffusion paper 6 is placed on the bottom of the positive electrode case 1. The air diffusion paper 5 may be made of alkali-resistant material, and although alkaline cellulose is used in this embodiment, it may be made of water-repellent material treated with fluororesin powder or the like. A water-repellent film 4 is disposed on the top of the air diffusion paper 3, and the outer diameter of the water-repellent film 4 is smaller than the outer diameter of the air diffusion paper filter. A porous fluororesin membrane was used as the water-repellent membrane 4.

On this water-repellent film 4, a positive electrode catalyst layer 5 mainly composed of activated carbon added with a silver catalyst, acetylene black, etc. and containing a flexible nickel current collector is further formed on the positive electrode catalyst layer 5, which is made of porous alkali cellulose. A separator 6 made of the following is arranged.

The cathode mixture 7 contains 72 parts by weight of zinc powder with a particle size of 48 to 150 mesh and an amalgamation rate of 7%, 24 parts by weight of a 40% potassium hydroxide aqueous solution, and a copolymer of acrylic acid and vinyl alcohol (gelled). Zinc powder is homogeneously dispersed in the gel electrolyte by kneading 4 parts by weight of Zinc powder.

This cathode mixture 7 is filled into a cathode case 8, and the above-described cathode case 1 and cathode case 8 are connected through a gasket 9 made of an alkali-resistant synthetic resin such as polypropylene, polyethylene, or nylon, and the opening of the cathode case 1 is folded. Seal by bending.

The amount of the copolymer of acrylic acid and vinyl alcohol used according to the present invention is preferably 05 to 10% by weight, more preferably 2 to 6% by weight, based on the cathode mixture.

If it is less than 0.05% by weight, a good gel state cannot be obtained;
If it exceeds 0% by weight, the gelation strength will be too strong, making it difficult to fill the cathode case and increasing the electrical resistance.

Comparative Example 1 A button-type zinc-air battery was obtained in the same manner as in Example except that carboxymethyl cellulose was used as the gelling agent.

Comparative Example 2 Except for using sodium polyacrylate as a gelling agent,
A button-type zinc-air battery was obtained in the same manner as in the example, but
The cathode mixture had stringiness and could not be filled into the cathode case smoothly.

(Effects) After storing the button-type zinc-air batteries obtained in Examples and Comparative Example 1.2 at 6or and saturated humidity for one month, liquid leakage occurred from the part where the opening of the positive electrode case was bent. The results of the investigation are shown in Table 1. The number of batteries was 50 in each case.

Table-1 It turns out that it is something.

[Brief explanation of drawings]

The figure is a longitudinal sectional view showing the present invention as a button-type zinc-air battery. 1...Cathode case 7...Cathode mixture 8...Cathode case Patent applicant Pentel Co., Ltd. Procedural Amendment May 7, 1985 Commissioner of the Patent Office Manabu Shiga Patent Application No. 85495 of 1984 2. Name of the invention Alkaline battery 3. Relationship with the case of the person making the amendment Patent applicant f] Tsuouku Ninenbashi Komi Sho Tau 103 Address 7-2 Kokinumachi, Nihonbashi, Chuo-ku, Tokyo (551)
The name has been corrected to Bentel Co., Ltd. "Potassium hydroxide."

Claims (1)

[Claims] 1. An alkaline battery, characterized in that, in a cathode mixture prepared by kneading powdered zinc, an alkaline electrolyte, and a gelling agent, a copolymer of acrylic acid and vinyl alcohol is used as the gelling agent.