JPS58137962A - Sealed dry cell - Google Patents

Abstract

PURPOSE:To suppress gas generation in a sealed dry cell, and suppress the capacity change and the dimensional change of the dry cell which are caused with the passing of time by using as a negative electrode, a mixture prepared by combining an amalgamated zinc powder with both a water-soluble macromolecular powder and ZnO. CONSTITUTION:A negative active material 2-a is prepared by mixing an amalgamated zinc powder with small amounts of at least one compound chosen from among sodium polyacrylate, carboxymethylcellulose and etherified starch, and adding ZnO to the mixture before thus obtained mixture is homogeneously mixed. Then, an amount corresponding to 60mAH theoretical capacity of the negative active material 2-a is packed into a sealed dry cell. A positive active material 4 is prepared by mixing 90 parts by weight of gamma-MnO2 powder with 10 parts by weight of acetylene black, combining 90 parts by weight of the mixture with 10 parts by weight of electrolyte prepared by saturating an aqueous solution containing 25% of ZnCl2 and 5% of NH4Cl with ZnO, and stirring and granulating thus obtained mixture before it is molded. After thus prepared positive pellet 4 and a positive seat 7 are pressed upon a positive can 5 so as to unify them with the positive can 5, a separator 3 is placed over the positive pellet 4, and the above mentioned negative active material 2-a is packed on the separator 3. Next, a negative can 1 to which a gasket 6 is attached is fitted inside the positive can 5 by pressure, and the opening end of the positive can 5 is inwardly caulked so as to seal the dry cell, thereby completing the assembly of a sealed dry cell.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in negative electrodes for sealed dry batteries. In recent years, dry batteries made by adding a small amount of ammonium chloride to zinc chloride have become easier to use than other primary batteries in terms of cost, leakage resistance, and high power, and have yielded more Il costs. On the other hand, with the development of small electronic horizontal winding, batteries are becoming smaller and thinner, and various button-shaped or coin-shaped batteries are exhibiting excellent characteristics.

An object of the present invention is to seal a conventional cylindrical zinc chloride dry cell to form a button-type dry cell, and to improve the discharge characteristics by replacing the zinc plate with frozen zinc powder.

Conventional zinc chloride dry batteries use 2% plates molded into cylinders or punched into disks and used as the negative electrode active material. In this ζ, H of the zn board.

In order to prevent gas generation, it is common practice to add an aqueous HgCJl solution to the electrolytic solution to amalgamate the surface of the ZN plate. However, when changing from a cylinder type to a button type, it is difficult to make H
It has become clear that the generation of l gas cannot be sufficiently prevented, and that the battery can gradually bulges after the battery is assembled.

The present invention is intended to eliminate this drawback, and will be explained below using examples.

FIG. 1 shows the structure of the battery of the present invention, and FIG. 2 shows a comparison of the conventional lateral movement. Next, the assembly order of the battery shown in FIG. 1 will be explained. 1 and 5 are negative electrode cans made of titanium material of JI day x type standard,
It is a positive electrode can that completely prevents corrosion of the electrolyte whose main component is zinc chloride, and also serves as a current collector terminal.

2-a is the negative electrode active material, commercially available ice water zinc powder (30-
100 mesh, Hl-amalgam product) K% Add a small amount of at least one of sodium polyallylate, carboxymethyl cellulose, and etherified starch, and further
After adding 3% of the total hit, mix uniformly and process.
Volume: Filled with an amount equivalent to 1160yxAH. Positive electrode active material 4
For this, commercially available 1-MgO powder and acetylene black were mixed in a ratio of (a) to 10 (weight S), and δ94 Z
@(:is + 5% Nk14CJ aqueous solution with Z%O
After adding 10fi to the total weight of the positive electrode and stirring and granulating the electrolytic solution saturated with This pellet was pressed together with the positive electrode pedestal 7 onto the positive electrode can 5 and integrated with the positive electrode can.This is called a positive electrode unit.Since the electrolyte in the positive electrode unit is in a state where it is easy to evaporate, the separator 3 was immediately removed. Place the anode can, fill it with the anode active material mentioned above, and push the anode can with the gasket 6 integrated into it from above, and push the open end of the cathode can 5 inward.
Seal by caulking, diameter 1], 66wm, thickness 3. I made a battery for Om.

In addition, in order to make a comparison with a conventional battery, as shown in Figure 2, a 0.05 m zinc plate was punched out into a disc shape, the surface in contact with the separator was amalgamated with a 316H9sCJ1m aqueous solution, and the surface in contact with the negative electrode can was amalgamated with a 316H9sCJ1m aqueous solution. A small amount of conductive adhesive (trade name: Dotite, Genji Kasei) containing carbon as the main component was applied and fixed. In addition, after adhesion, LCR Me-7Il-
When the contact resistance between the zinc plate and the negative electrode can was measured, it was 1.0.
It was confirmed that the contact resistance was at a completely acceptable level. When a zinc plate is used, it has a larger bulk density and a larger energy density than zinc hydrate powder, so the negative electrode can secure a theoretical capacity of 7011AH. The electrolyte composition is 0.5'Ik Hffs in addition to the above-mentioned total amount.
Cj! An aqueous solution containing 0.03% by weight was used.

Other assembly methods were carried out in exactly the same manner as for the battery of the present invention. The button-type dry battery thus obtained was stored in a dry atmosphere at 60° C. for 1000 hours, and then dimensional changes and electrical characteristics were compared and investigated. The average value of 110 samples at each point was plotted in Figures 3 and 4. In the figure, M indicates a battery of the present invention, and B indicates a conventional battery.

Figure 3 shows the storage time and amount of change in total thickness when the initial battery total thickness (2.95 m) is set to zero.The battery of the present invention has no swell, while the conventional battery has no swell. , 500
After ~1000 hours, the swelling increased dramatically. If the time is less than 500 hours, the can strength is greater than the increase in internal pressure, so bulging is suppressed, but if it exceeds 750 hours, the internal pressure overcomes and the bulge tends to gradually increase. The causes of the increase in internal pressure are estimated to be (1) gas generation from the zinc plate, and gas generation due to the reaction between impurities in the conductive adhesive and the zinc plate. In order to investigate the presence or absence of gas generation due to the reaction with zinc hydride powder, a comparison was made using a gas meter (I/Ik large scale, 3cc) as shown in Figure 5. The weight of zinc yen and zinc chloride powder is
The amount of electrolyte is the same as that in one battery, and the amount of electrolyte is approximately 20 times the amount in one battery. The amount of electrolyte is injected into the gas meter, degassed under reduced pressure, and after death, it is placed in a water bath at 60 ° C. Then, the increment on the scale at fixed time intervals was read. Figure 6 shows changes in the amount of gas generated. In the figure, M is zinc hydrate powder and B is a zinc disk. As is clear from FIG. 6, the surface of the zinc disk is amalgamated and the IIQzCJl solution is added to the electrolyte. However, gas is generated during high temperature storage. On the other hand, when zinc chloride powder is used, there is no generation of ore or gas, and the suppressing effect is remarkable.

Furthermore, as shown in FIG. 7, the amount of gas generated was compared between the case of using the 1-Yonghwa zinc powder alone and the case of adding a water-soluble polymer powder such as carboxymethyl cellulose to the zinc hydrate powder.

In this figure, M is when nothing is added to the zinc hydrate powder, B is when only water-soluble polymer powder is added,
C is Z%O and polyvinyl alcohol is added, D
IIiZKO and water-soluble polymer powder (ZsO and carboxymethylcellulose, Z%0 and sodium polyacrylate, t
2@0 and etherified starch) are added. It was found that when 1carboxymethyl cellulose, sodium polyacrylate or etherified starch was added with Zrei O, the suppressive effect was significant.

The reason why this suppressing effect occurs is not clear, but the PR change of the electrolyte occurs at high temperatures, and the addition of ZnO causes 11
It is presumed that ions can be sufficiently supplied, and furthermore, the water-soluble polymer contributes to suppressing dissolution by 2%.

As described above in detail, water-soluble polymer powder and Z%O
By using t-added zinc chloride powder for the negative electrode, it is possible to produce a battery that suppresses gas generation and suppresses changes in capacity and dimensions over time, so its industrial value is extremely large.

[Brief explanation of the drawing]

Figures 1 and 2 are longitudinal cross-sectional views of the battery of the present invention and a conventional battery, Figures 3 and 4 are comparison diagrams of battery swelling amount and battery capacity, Figure 5 is a conceptual diagram of a gas meter, Figure 6 FIG. 7 is a diagram showing a comparison of gas generation suppressing effects when using the same gas meter. l...Negative electrode 2a...Negative electrode mainly made of zinc oxide powder 2h...Negative electrode 3 mainly made of zinc disk...Separator 4...Positive electrode 5...Positive electrode can 6...E gasket 7...Positive electrode pedestal and above Applicant Daini Seikokin Co., Ltd. Agent Patent Attorney Mogami

Claims (1)

[Claims] Ex) A battery using manganese dioxide as a positive electrode active material and zinc chloride as an electrolyte, and a battery using zinc chloride powder as a negative electrode active material, in which 2% water-soluble polymer powder and 2% water-soluble polymer powder are used in the negative electrode. 0
Sealed dry cell with added powder. 121 Etherified starch as water-soluble polymer powder,
The sealed dry battery according to claim 1, which is made of either carboxymethyl cellulose or sodium polyacrylate.