JPS5826148B2 - alkaline dench - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an alkaline battery using silver peroxide (Age) as the main positive electrode active material.

This type of battery has a positive electrode active material of silver peroxide (Age) of 1
It has the advantage of having a theoretical capacitance approximately 1.8 times higher than silver oxide (Ag20), but on the other hand, it has the disadvantage that silver peroxide (Ago) is an extremely thermodynamically unstable substance. ing.

That is, it is known that silver peroxide (Age) rapidly decomposes in an alkaline aqueous solution and at high temperatures according to the decomposition reaction: 2AgO→Ag2O+1/20□.

In addition, the rate of decomposition increases as the alkali concentration increases.
Or, it has been confirmed that it increases as the temperature rises.

Therefore, when a highly concentrated alkaline electrolyte of 30 to 40%, such as that used in conventional monovalent silver oxide batteries, is used in a battery using silver peroxide as the anode active material, AgO is
This decomposes into 20 g and 20 g, resulting in significant gas generation, which has the drawbacks of severe capacity reduction, battery bulge, and liquid leakage.

Furthermore, when used as a battery with the addition of highly conductive graphite or the like to the anode active material, as has been done in the past, it has the advantage of low internal resistance, but on the other hand, it has a large number of active sites for battery reactions. There is a drawback that the high potential section at the beginning of discharge is long, and AgO becomes unstable during long-term storage.

In order to eliminate the above-mentioned drawbacks, the present invention adds an anode mixture to AgO as an anode active material and a solid lubricant with almost no conductivity such as molybdenum disulfide, talc, pyrophyllite, or graphite fluoride. By using a pressed anode molded body, it can withstand long-term storage, has a short high potential period,
The purpose is to provide a battery with a large discharge capacity per unit volume.

Next, embodiments of the present invention will be described.

Example 1 An anode mixture of 4% fluorinated graphite and 96% Ag was pressurized at 8 ton/ffl to form an anode molded body, and combined with a cathode mixture mainly composed of zinc fluoride, the anode mixture was prepared according to JIS-GS-12. I made a type of battery.

Example 2 Molybdenum disulfide was heated to 0.5, 1, and 2°3.5, respectively.
, 10, and 20% AgO was pressurized at 8 ton/ffl, and a JIS-GS-12 type battery was produced in the same manner as in Example 1.

In a battery using AgO as the anode active material, at the beginning of discharge, 2e-+2AgO+H20-)Ag20+2(OH)-
A high potential appears due to the reaction.

When Ag2O is generated, 2e +Ag2O+)(2Q→2Ag+2(OH)
-2Ag+AgO-)Ag20 reaction continues, so the potential returns to normal.

Initially, a high potential appears while AgO is in contact with the electrolyte and the anode lead, and AgO is insulated from at least one of the electrolyte and the anode lead and comes into contact with Ag or Ag2O. When this happens, the potential returns to normal.

In the current graphite-added products, due to the high conductivity of graphite, the graphite becomes the anode lead, and almost all of the AgO is in contact with the graphite, which serves as the anode lead.

Therefore, when the electrolyte is impregnated, a high potential appears and all A
Connect until the gO particle surface becomes Ag2O or Ag.

In addition, those without graphite have poor formability, and AgO
This has the disadvantage that the discharge capacity is small due to the low filling rate.

On the other hand, instead of graphite, solid materials with almost no conductivity such as MOS2, (CF)n, pyrophyllite, and talc can be used.
*AgO anode body shape with added body lubricant Even if the electrolyte comes into contact with AgO, the parts that are not in contact with the anode lead will not react.

Only a very small amount of AgO that is in contact with the lead and in contact with the electrolyte reacts, and after that, the Ag produced by the reaction of AgO becomes the electrode, so 2Ag+Ag0-+Ag
, 20 reactions occur and do not show high voltage.

Next, Table 1 shows the discharge capacity of the batteries of each example in 75 to 8 constant resistance discharge.

Note that in Table 1, the area within 0 indicates a high potential, and each data is an average value of five batteries.

Further, Sample/169 is a conventional sample, and Sample/410 is a sample in which no additive is added to AgO for comparison.

As can be seen by comparing Sample 169 of the conventional example and Samples 41 to 8 of the examples of the present invention, when a solid lubricant with almost no conductivity is added, the inside of the anode mixture molded body is in contact with the anode lead. Therefore, a battery with less deterioration during storage and a large weight capacity after storage for 6 months can be obtained.

In the case of MoB2, the effect is remarkable when the amount added is 2 to 5% by weight.

On the other hand, in Samples A and 10, which do not contain any additives, the volume ratio of AgO in the anode molded body is small, so the discharge capacity when used as a battery is small, and the large porosity makes it easy for the electrolyte to penetrate, so it will not last long. The discharge capacity after storage is also small.

The discharge characteristics are shown in FIGS. 1 and 2.

FIG. 1 shows a conventional battery (sample/169), and FIG. 2 shows a battery according to the present invention (sample 44).

As described above, according to the present invention, since a solid lubricant with almost no conductivity is mixed into Ago as the anode active material, it has excellent long-term storage stability, has a short high potential section, and
An alkaline battery with a large capacity per unit volume can be obtained.

[Brief explanation of the drawing]

FIG. 1 shows a conventional battery using AgO as the anode active material, and FIG. 2 shows a battery using AgO as the anode active material according to the present invention. 1: Conventional battery (immediately after manufacture), 2: Conventional battery (after storage for 6 months), 3: Battery of the present invention (immediately after manufacture), 4: Battery of the invention (after storage for 6 months).

Claims (1)

[Claims] 1. In a battery using silver peroxide (Age) as an anode active material, an anode mixture prepared by adding 0.5 to 20% by weight of a solid lubricant with almost no conductivity to the anode active material was pressurized and molded. An alkaline battery characterized by using a molded anode.